Frost dates and the length of the growing season

Written by Science Knowledge on 10:31 PM

You should know two very important weather dates for your area if you want to grow vegetables successfully:

✓ The average date of the last frost in spring
✓ The average date of the first frost in fall

These frost dates tell you several important things:

✓ When to plant: Cool-season vegetables are generally planted 4 to 6 weeks before the last spring frost. Fall planting of cool-season vegetables is less dependent on frost dates, but it’s usually done 8 to 12 weeks before the first fall frost. Warm-season vegetables are planted after the last spring frost or in late summer in warm areas for a fall harvest.

✓ When to protect warm-season vegetables: Frosts kill warm-season vegetables. So the closer you plant to the last frost of spring, the more important it is to protect plants. And as the fall frost gets closer, so does the end of your summer vegetable season — unless, of course, you protect your plants

✓ The length of your growing season: Your growing season is the number of days between the average date of the last frost in spring and the average date of the first frost in fall. The length of the growing season can range from less than 100 days in northern or cold winter climates to 365 days in frost-free southern climes. Many warm-season vegetables need long, warm growing seasons to properly mature, so they’re difficult, if not impossible, to grow where growing seasons are short.

How are you to know whether your growing season is long enough? If you check mail-order seed catalogs or even individual seed packets, each variety will have the number of days to harvest or days to maturity (usually posted in parentheses next to the variety name). This number tells you how many days it takes for that vegetable to grow from seed (or transplant) to harvest. If your growing season is only 100 days long and you want to grow a melon or other warm-season vegetable that takes 120 frost-free days to mature, you have a problem. The plant will probably be killed by frost before the fruit is mature. In areas with short growing seasons, it’s usually best to go with early ripening varieties (which have the shortest number of days to harvest).

However, you also can find many effective ways to extend your growing season, such as starting seeds indoors or planting under floating row covers (blanketlike materials that drape over plants, creating warm, greenhouselike conditions underneath).

There you have it; now you know why frost dates are so important. But how do you find out dates for your area? Easy. Ask a local nursery worker or contact your local Cooperative Extension office (look in the phone book under county government).

Frost dates are important, but you also have to take them with a grain of salt. After all, these dates are averages, meaning that half the time the frost will actually come earlier than the average date and half the time it will occur later. You also should know that frost dates are usually given for large areas, such as your city or county. If you live in a cold spot in the bottom of a valley, frosts may come days earlier in fall and days later in spring. Similarly, if you live in a warm spot or you garden in a microclimate, your frost may come later in fall and stop earlier in spring. You’re sure to find out all about your area as you become a more seasoned vegetable gardener and unearth the nuances of your own yard. One thing you’ll discover for sure is that you can’t predict the weather.

Listening to your evening weather forecast is one of the best ways to find out whether frosts are expected in your area. But you also can do a little predicting yourself by going outside late in the evening and checking conditions. If the fall or early spring sky is clear and full of stars, and the wind is still, conditions are right for a frost. If you need to protect plants, do so at that time.

Source of Information : vegetable gardening for dummies

Understanding Veggie Varieties

Written by Science Knowledge on 10:26 PM

Before you go drooling over the luscious veggies in catalogs, in garden centers, and online, it’s good to know a little about the varieties you can choose from. If you select your veggie varieties before you design your garden, you can ensure that you have the proper amount of space and the best growing conditions.

A variety is a selection of a particular type of vegetable that has certain predictable, desirable traits. These traits may include the following:

✓ Adaptation: Some varieties are particularly well adapted to certain areas and climates. For example, some tomato varieties produce good-tasting fruit in the cool, foggy coastal climates of the Pacific Northwest. And certain bean varieties are better adapted to the hot, dry deserts of the American southwest.

✓ Appearance: You can choose from a rainbow of fruit and leaf colors, such as purple peppers, yellow chard, and orange tomatoes. Leaf textures and shapes range from frilly to smooth to puckered. The flowers of some vegetables, such as okra and eggplant, are attractive in their own right. You get the idea. The more beautiful the vegetables, the more beautiful the vegetable garden — and the more stunning the food.

✓ Cooking and storage characteristics: Certain varieties of beans and peas, for example, freeze better than others. Some winter squash varieties may be stored for months, but others need to be eaten immediately.

✓ Days to maturity (or days to harvest): Days to maturity refers to the number of days it takes (under normal conditions) for a vegetable planted from seed (or from transplants) to mature and produce a crop. This number is especially important for vegetable gardeners who live in short-summer climates. Average days to maturity are listed for each type of vegetable in the appendix.

✓ Extended harvest season: A certain variety of corn, for example, may ripen early or late in the season. By planting varieties that ripen at different times, you can start harvesting as early as 60 days after seeding and continue for 5 or 6 weeks. Seed catalogs and packages often describe varieties as early season, midseason, or late season in relationship to other varieties of the same vegetable.

✓ Pest resistance: Many vegetable varieties are resistant to specific diseases or pests — a very important trait in many areas. Some tomato varieties, in particular, have outstanding disease resistance. You also can read about specific pestresistant varieties of individual vegetables.

✓ Plant size: The trend in vegetable breeding is to go small. Tomato, cucumber, and even winter squash varieties are available in dwarf sizes. These varieties are perfect for container growing or small-space gardens.

✓ Taste: Pick a flavor and you can find a vegetable that stars in it. You can grow fruity tomatoes, super-sweet varieties of corn, bitter melons, and spicy peppers. You’ll discover flavors for every taste bud.

To realize the scope of your vegetable variety possibilities, see the individual vegetable descriptions in Part II. It’s also important to note that you can categorize a variety as a hybrid, an open-pollinated, or an heirloom variety. Here’s what these terms mean:

✓ Hybrid: Hybrid seeds (also known as F-1 hybrids) are the result of a cross of selected groups of plants of the same kind, called inbred lines. (A cross is when pollen from one flower fertilizes a flower from another similar plant, resulting in seed.) Hybrid seeds generally are more expensive than open-pollinated seeds, and they can’t be saved and planted the next year because the offspring won’t have the same characteristics as the parents. If you did plant them next year, you’d get a mix of characteristics — some desirable and some not. The plants are uniform, but they often lack a diversity of shapes, colors, sizes, and flavors. However, hybrid plants are more vigorous, productive, and widely adapted than other varieties.

✓ Open-pollinated: Open-pollinated varieties basically are inbred lines allowed to pollinate each other in open fields. They produce offspring that are similar to their parents. Before the arrival of hybrids, all vegetable varieties were open-pollinated. Some gardeners like these varieties for their flavor, their diversity, and the fact that they can save the seeds each year to replant. The resulting offspring are pretty predictable, but they don’t provide the consistency of hybrids.

✓ Heirloom: Any open-pollinated variety that’s at least 50 years old is generally considered an heirloom. Heirlooms are enjoying quite a revival because of the variety of colors, tastes, and forms that are available. They’re worth trying, but keep in mind that some varieties may not have the disease resistance and wide adaptability that hybrids generally have.

One category generally available only to commercial farmers is that of the genetically modified variety. This kind of plant has a gene from a completely unrelated species inserted into it so that it exhibits a certain trait. For example, geneticists have inserted a gene of the biological pesticide Bt into potatoes so that when the Colorado potato beetle (their biggest enemy) eats a potato’s leaves, it also eats the pesticide and dies. Many questions exist about the longterm health risks and environmental safety of manipulating the gene pool so dramatically and quickly. For this reason, genetically modified organisms (GMOs) aren’t allowed in organic gardening.

Source of Information : vegetable gardening for dummies

Deciding Where to Put Your Vegetable Garden

Written by Science Knowledge on 10:17 PM

Choosing a site is the important first step in planning a vegetable garden. This may sound like a tough choice to make, but don’t worry; a lot of the decision is based on good old common sense. When you’re considering a site for your garden, remember these considerations:

✓ Keep it close to home. Plant your garden where you’ll walk by it daily so that you remember to care for it. Also, a vegetable garden is a place people like to gather, so keep it close to a pathway.

Vegetable gardens used to be relegated to some forlorn location out back. Unfortunately, if it’s out of sight, it’s out of mind. I like to plant vegetables front and center — even in the front yard. That way you get to see the fruits of your labor and remember what chores need to be done. Plus, it’s a great way to engage the neighbors as they stroll by and admire your plants. You may even be inspired to share a tomato with them.

✓ Make it easy to access. If you need to bring in soil, compost, mulch, or wood by truck or car, make sure your garden can be easily reached by a vehicle. Otherwise you’ll end up working way too hard to cart these essentials from one end of the yard to the other.

✓ Have a water source close by. Try to locate your garden as close as you can to an outdoor faucet. Hauling hundreds of feet of hose around the yard to water the garden will only cause more work and frustration. And, hey, isn’t gardening supposed to be fun?

✓ Keep it flat. You can garden on a slight slope, and, in fact, a south-facing one is ideal since it warms up faster in spring. However, too severe a slope could lead to erosion problems. To avoid having to build terraces like Machu Picchu, plant your garden on flat ground.

A bit of science also is involved in choosing the right site. Microclimates are small areas of your yard whose temperatures and related growing conditions are slightly different from the overall climate of your yard, neighborhood, or town. These differences usually are caused by large objects, such as your house, a wall, or a tree. For example, the south side of your house may be hotter than the rest of your yard, because the sun reflects off the walls and the house blocks prevailing cold winds. Or an area under a large tree may be cooler than the rest of the yard because of the shade provided by the tree’s canopy.

How big is too big for a veggie garden? If you’re a first-time gardener, a size of 100 square feet is plenty of space to take care of; I like to tell beginning gardeners to start small and build on their success. However, if you want to produce food for storing and sharing, a 20-foot-x-30-foot plot (600 square feet total) is a great size. You can produce an abundance of different vegetables and still keep the plot looking good.

Speaking of upkeep, keep the following in mind when deciding how large to make your garden: If the soil is in good condition, a novice gardener can keep up with a 600-square-foot garden by devoting about a half-hour each day the first month of the season; in late spring through summer, a good half-hour of work every 2 to 3 days should keep the garden productive and looking good. Keep in mind that the smaller the garden, the less time it’ll take to keep it looking great. Plus, after it’s established, the garden will take less time to get up and running in the spring.

Source of Information : vegetable gardening for dummies

A Few Good Reasons to Grow Your Own Food

Written by Science Knowledge on 9:43 PM

It’s almost predictable: When economic times are hard, people head to the garden. It happened in the 1920s with Liberty Gardens, in the 1940s with Victory Gardens, and in the 1970s with increases in oil and food prices. Similarly, with current concerns about food safety, global warming, carbon footprints, and pollution, along with a desire to build a link to the Earth and our own neighborhoods, food gardening has become a simple and tasty solution.

Food gardens aren’t just in backyards anymore. People grow food in containers on decks and patios, in community gardens, at schools, at senior centers, and even in front yards for everyone to see. Food gardens are beautiful and productive, so why not let everyone enjoy the benefits? I describe the advantages to growing your own food in the following sections.


Improve your health
We all know we’re supposed to eat more fruits and vegetables every day. It isn’t just good advice from mom. Many vegetables are loaded with vitamins A and C, fiber, water, and minerals such as potassium. A growing body of research shows that eating fresh fruits and vegetables not only gives your body the nutrients and vitamins it needs to function properly, but it also reveals that many fruits and vegetables are loaded with phytochemicals and antioxidants — specific compounds that help prevent and fight illness.

While specific vegetables and fruits are high in certain nutrients, the best way to make sure you get a good range of these compounds in your diet is to “eat a rainbow.” By eating a variety of different-colored vegetables and fruits, you get all the nutrients you need to be healthy.

While eating fruits and vegetables is generally a great idea, the quality and safety of produce in grocery stores has been increasingly compromised. Whether it’s Salmonella on jalapeño peppers or E. coli in spinach, warnings seem to be happening every year. Also, some people are concerned about pesticide residues on their produce. A list called the “Dirty Dozen” points out the vegetables and fruits most likely to contain pesticide residues. Here’s the list: apples, bell peppers, celery, cherries, imported grapes, nectarines, peaches, pears, potatoes, red raspberries, spinach, and strawberries. What better way to ensure a safe food supply free of biological and pesticide contamination than to grow your own? You’ll know exactly what’s been used to grow those beautiful crops.


Save some cash
You can save big money by growing your own vegetables and fruits. In fact, depending on the type and amount you grow, you can save hundreds of dollars. By spending a few dollars on seeds, plants, and supplies in spring, you’ll produce vegetables that yield pounds of produce in summer. Instead of having to go to the grocery store to buy all that produce, you’ve got it ready for the picking for free in your yard. It’s your own personal produce department! You’ll save hundreds of dollars on your grocery bill each year by growing a garden.

Here’s just one example of how a vegetable garden can save you some cash. The 20-foot-by-30-foot production garden highlights many favorite vegetables. I also include some plans for succession cropping and interplanting. When I indicate succession crops, I’m assuming two crops in one growing season. I’m also assuming 8-foot-long raised beds with rows with space to walk between the beds down the center.

To show you how the garden saves you money, the following list provides vegetable yields and the price per pound of each crop. However, keep in mind that these are general averages. I’ve erred on the conservative side with many yields. Yields, after all, can vary depending on the location, variety, and growth of your crops. The prices are based on national average prices from the USDA Agricultural Marketing Service for those vegetables grown organically in summer. Again, these numbers may vary depending on
the year and location in the country. However, even with all these variables, you can see that you grow more than 300 pounds of produce worth more than $600 just by working your own garden!

If you grew the garden depicted your initial investment of $70 to get started will yield 350 pounds of vegetables. If you purchased the same 350 pounds of vegetables in a grocery store, you’d have to pay more than $600. So, as you can see, you’re saving money and getting great food to eat.


Help the environment
Your tomatoes, lettuces, and melons from the grocery store cost more than just the price to produce them. It’s estimated that the average produce travels up to 1,500 miles to get from farm to grocery store, and that’s just vegetables and fruits produced in the United States. Increasingly, produce is being imported from foreign countries, such as China and Chile. The fossil fuels used to transport these vegetables increases air pollution and global warming. So, one of the big-picture reasons for growing your own produce is to fight these effects on our planet.

Plus, by growing your own vegetables, fruits, and herbs, you also reduce the amount of pollution that’s created on the farm. Regardless of it being a conventional or organic farm, many large operations tend to use lots of fertilizers, pesticides, and herbicides to grow their crops. Unfortunately, some of these additives end up as sources of pollution (and their creation requires fossil fuels). By growing your own produce using a minimal amount of these inputs, you can reduce the amount of chemical and fertilizer pollution that ends up in waterways around the country. For more information on gardening sustainably, check out Sustainable Landscaping For Dummies by Owen Dell (Wiley).


Increase your quality of life
A less tangible (but still important) reason to grow your own vegetables is related to quality of life. Vegetable gardening is a great way to unwind after a hard day. You can achieve a simple pleasure and satisfaction in roaming through your garden, snacking on a bean here and a cherry tomato there, pulling a few weeds, watering, and enjoying the fruits of your labors. It’s an immediate, simple satisfaction in a world that so often is complicated and complex.

Also, if you garden with others in a community garden, you’ll create new friendships and bonds with your neighbors. According to the NGA food gardening survey that I describe earlier in this chapter, more than a million community gardens exist across the country. Often community gardens become a focal point for neighborhood beautification, education, and development projects. When the gardens are sown, people start taking increased interest and pride in their neighborhood and how it looks. Often crime, graffiti, and vandalism are reduced just by creating a garden where people can gather together. And you thought all you were doing is growing a few vegetables!

For more information about starting a community garden or to find one in your area, contact the American Community Gardening Association at communitygarden.org.

Source of Information : vegetable gardening for dummies

Food Gardening: It’s Popping Up Everywhere

Written by Science Knowledge on 9:25 PM

While food gardening is a great activity to do in your yard, it’s also part of a growing trend of people wanting to eat better, grow some of their own food, and have more control on the quality of their food supply. What better way to ensure that you eat healthy food than growing it yourself?

In early 2009, the National Gardening Association (NGA) completed a survey that characterized food gardening in the United States. Here’s what it found:

✓ Approximately 23 percent, or 27 million households, had a vegetable garden in 2008. That’s 2 million more than in 2007. The number of food gardeners increases to 31 percent, or 36 million households, if you include those people growing fruits, berries, and herbs.

✓ The average person spends about $70 on their food garden every year. (I wish I could keep my spending that low!) The total nationwide is $2.5 billion spent on food gardening. I explain what you gain from that $70 in comparison to what you’d spend at the grocery store.

✓ The average vegetable garden is 600 square feet, but 83 percent of the vegetable gardens are less than 500 square feet. Nearly half of all gardeners grow some vegetables in containers as well.

✓ The typical vegetable gardener is college educated, married, female, age 45 or older, and has no kids at home. And almost 60 percent of vegetable gardeners have been gardening for less than five years.

✓ The typical reasons for vegetable gardening in order of importance are: to produce fresh food, to save money, to produce better-quality food, and to grow food you know is safe.

There you have it. Lots of food gardeners are out in their crops, and the numbers are growing faster than corn in July. You may grow only a small food garden, but when all the gardens are added together, the impact is enormous. Need more proof? Let me show you!

The gross national garden product (GNGP) is the combined amount of money that can be produced from America’s food gardens. Here’s how the NGA figured it out (time for some math fun!):

✓ About 36 million households grow vegetables, berries, fruits, and herbs. The average garden size is 600 square feet. The NGA estimates that you can produce about 1/2 pound of vegetables per square foot of garden per year. That’s about 300 pounds of vegetables in the average garden. The average price, in season, of vegetables is about $2 per pound, so the average vegetable garden produces $600 worth of produce. So, Americans invest an average of $70 to yield $600 worth of produce every year. Wow! That’s a good return in my book!

✓ When you figure the numbers nationally, 36 million households spend $2.5 billion to yield a GNGP of more than $21 billion worth of vegetables each year. That’s a stimulus plan I can live with!

Source of Information : vegetable gardening for dummies

A Cornucopia of Vegetables to Grow

Written by Science Knowledge on 9:17 PM

You can grow many different types of vegetables in your yard — and not just in the backyard. These days veggies are pretty enough to be front and center. The following sections describe some of the most popular to get you started. Hopefully you have plenty of room!


Tomatoes
Tomatoes are the most popular vegetable grown — and for good reason. The difference between a vine-ripened fruit and one picked green, gassed, and shipped hundreds of miles to your grocery store is incomparable. You can choose from container varieties that produce fruit the size of a pea and giant plants that grow to the height of a garage and produce fruits the size of a softball! You can even grow varieties of tomatoes with fruits every color of the rainbow except blue (however, I wouldn’t be surprised to see that color someday either).

Tomatoes love the heat and sun and require fertile soil and support. Unless you’re growing the dwarf varieties, stakes, cages, trellises, teepees, and arbors are essential for keeping plants growing upright and strong. You only need a few plants to keep your family in tomatoes most of the summer.


Peppers and eggplants
Peppers and eggplants are related to tomatoes, but they’re a little more homogeneous in their plant size. However, what they lack in plant variety, they make up in fruit uniqueness. Pepper fruits come shaped as bells or as long and thin tubular shapes. Some are as sweet as candy and others are hot enough to burn your mouth.

Pepper fruits mostly start out green and end up red, but where they go, colorwise, in between is amazing. You can experiment with chocolate-, yellow-, ivory-, purple-, lavender-, and orange-colored fruits that can be eaten raw or used in a multitude of cooked dishes. Eggplants also have burst onto the scene with varieties that produce unique-colored fruits, including white, purple, striped, and even orange.

If you can grow a tomato, you can grow peppers and eggplants. They need similar growing conditions. Plus, I love them as ornamental edibles. Not only do they look good in flower beds and containers, but you can eat them too!


Carrots, onions, and potatoes
Get to the root of the matter by growing carrots, onions, and potatoes. (I know, I couldn’t resist the play on words!) Carrots, onions, and potatoes love cool soil and cool weather conditions. Start them in spring for an early summer crop or in summer to mature in fall. Here are a few fun facts on each group:

✓ Carrots: Carrot varieties are either short and squat or long and thin. You can even get colors other than orange, including red, purple, yellow, and white. Because their seeds are so small and take a while to germinate, carrots can be difficult to get started. But once they’re growing you’ll soon be munching on roots.

✓ Onions: Onions are adapted to the north and south depending on the variety. Some are sweet and can be eaten out of hand, but others are pungent and best for cooking and storing in winter. You can grow onions from seed, sets (bulbs), or plants.

✓ Potatoes: Potatoes are an easy cool-season crop to grow because you plant part of the potato to get new plants. If you cover the tubers with soil, hill them up, and keep them watered, you’ll be rolling in spuds come summer.


Peas and beans
Peas and beans are like brothers. They’re in the same family and share similar traits, but in some ways they’re very different!

✓ Peas are cool-season-loving crops that produce either plump or flat pods depending on the variety. With some pea varieties you eat pods and all. With others you eat just the peas inside.

✓ Beans love the heat. They’re one of the easiest vegetables to grow. They come in bush and twining or pole bean forms. Both are great vegetables in the garden because they require little fertilizer and care once they’re up and running.


Cucumbers, melons, pumpkins, and squash
I affectionately call cucumbers, melons, pumpkins, and squash the “viners.” They love to ramble about the garden, taking up space and producing loads of fruit. But even if you’re a small-space gardener, you can still grow these space hogs. Newer varieties of cucumbers, squash, and melons can fit in a small raised bed or even a container.

One common trait of these vegetables is that they need heat, water, fertility, and bees. Bees? Yes, bees. Most of these squash family crops need to be cross-pollinated to produce fruit, so bees are critical to success. If you’re growing other vegetables, flowers, and herbs, you’re sure to have some bees flying about to do the dirty work. Some members of this veggie family can be prolific, so don’t plant lots of zucchinis, cucumbers, and pumpkins. Then again, if you really want to share the harvest you can plant a bunch to give away!


Broccoli, Brussels sprouts, cabbage, and cauliflower
Broccoli, Brussels sprouts, cabbage, and cauliflower are similar in how they grow and what they need to grow. However, their differences come in the parts you eat. Here’s the lowdown:

✓ After you pick the heads of cabbage and cauliflower, the plant is finished and stops producing.

✓ After you pick broccoli heads, you’ll keep getting more broccoli side shoots to eat all season long.

✓ Brussels sprouts are like your crazy Uncle Louis. He looks a little strange, and you don’t know where he came from. Brussels sprouts produce cabbagelike balls all along a straight stem. Keep picking the sprouts starting from the bottom to the top of the stalk and working up until it stops producing because of the cold.

This group of veggies is productive and serves as a great addition to a coolweather spring or fall garden.


Lettuce, spinach, Swiss chard, and specialty greens
If you’re looking for quick rewards: lettuce, spinach, chard, and wild greens, such as dandelions. Because you don’t have to wait for greens to form fruits (you’re just eating the leaves), you can pick them as soon as your stomach rumbles and the leaves are big enough to munch. They mostly love cool weather, so start early in spring and then keep planting and harvesting.

Greens are one of the best container vegetables to grow because they’re easy and adaptable. You can mix and match lettuce varieties to produce different colors and textures that look beautiful and taste divine.


An assortment of other great veggies
In the previous sections, I just touch the tip of the iceberg when it comes to what to grow for vegetable varieties. There are so many more vegetables to grow; all you have to do is wander down the produce aisles at the local grocery store and think, do I like to eat that? Watch out or you may get hooked and start growing so many vegetables you’ll have to open a restaurant. Vegetable gardening really can become that much fun.


Non-vegetable edibles
Don’t limit yourself to growing just vegetables in the vegetable garden. That would be silly! Berries, such as blueberries, strawberries, and raspberries, and herbs, such as basil, parsley, and chives, are great additions to your yard. They produce fruit, spice up a meal, and look beautiful. Need some inspiration? Here are some suggestions:

✓ Consider having a strawberry patch in your garden.

✓ Landscape your yard with blueberry bushes or a hedge of raspberries.

✓ Mix herb plants around vegetable plants or give them their own space in the garden. Herbs also grow well in containers mixed with flowers. I love growing rosemary in a deck planter each year for the attractive foliage and the enticing aroma.

Source of Information : vegetable gardening for dummies

The Basics of Planning a Veggie Garden

Written by Science Knowledge on 9:06 PM

When’s the best time to start vegetable gardening? Right now! Here are the basics on how to decide where to grow yours:

✓ Find a spot close to the house that you walk by daily so you don’t forget about your project.

✓ Find a spot that gets at least 6 hours of direct sun a day.

✓ Find a spot that has great soil.

Keep your new garden small. You can be just as productive in a small raised bed garden, container, or small kitchen garden as you would be if you tilled your whole backyard. Start small, be successful, and then get bigger (if you want).

What should you put in your new garden? Well, you have many vegetable options when it comes to deciding what you can grow, so it’s going to be tough deciding which ones to plant. The most important rule I can tell you is to grow what you like to eat. Yes, folks, this is all about taste. So no matter what people say about how easy beans are to grow, don’t grow them if you hate to eat them. (Of course, after tasting fresh green beans from the garden, you may change your tune.) Grow a mix of varieties of favorite vegetables that you and your family will love. Also, try a few different ones to stretch your imagination.

Source of Information : vegetable gardening for dummies

Why Have Your Own Vegetable Garden?

Written by Science Knowledge on 9:01 PM

Over the years people had drifted away from vegetable gardening in the spirit of progress and affluence. However, more recently people are once again realizing that growing their own food, although not as critical to survival as it once was, is an important part of a healthy body, mind, spirit, lifestyle, and community. More people are again turning to vegetable gardening as a means of food and as a hobby. Even the president and first lady have installed a vegetable garden at the White House. Vegetable gardening is officially back!

Who can resist the flavor, smell, and texture of food literally picked minutes before you eat it? It you’ve ever sunk your teeth into a sun-warmed, ripe tomato and felt the juices and flavors explode in your mouth, you’ll know what I mean.

But vegetable gardening isn’t just about taste. It’s about safe food that’s produced close to home. It’s about knowing what has been sprayed on that food. It’s about feeding your friends and family nutritious food that’s high in vitamins and antioxidants (cancer-fighting compounds). It’s about connecting with your neighbors and community as you experiment with ethnic dishes using exotic ingredients grown in your not-so-exotic backyard. It’s about reducing pollution and global warming by not buying produce that’s shipped hundreds of miles to your local grocery store. Finally it’s about reclaiming your ability to grow some of your own food, even if it’s a container of basil, to have a little more control in your life.

Source of Information : vegetable gardening for dummies

Cancer Prevention

Written by Science Knowledge on 12:22 AM

Now that you understand how cancer works, it’s time to ask how you can stop it. Unfortunately, there’s no single measure to prevent cancer. In fact, your body is already using all the cancer-prevention programs we know about.

Some cancers are closely associated with particular lifestyle risks. For example, sun exposure is linked to skin cancer and cigarettes are tied to lung cancer. Minimize these risks, and you’re likely to avoid the cancers they cause. But many more cancers aren’t so clear-cut. They arise spontaneously and unexpectedly, after a lifetime of bodily wear and tear.

Your best bet is to detect the problem early. If you can catch a cancer before it metastasizes, your odds of conquering it are dramatically better. Unfortunately, many cancers have subtle symptoms that aren’t initially troubling. Some symptoms—like weight loss, fevers, swollen lymph nodes, or a feeling of constant tiredness—may indicate cancer, but are usually caused by something less serious, like an infection. And a few cancers (for example, pancreatic cancer) are virtually undetectable in their early stages.

To give yourself the best odds, you need to be eternally vigilant for problem signs. Some examples include unexplained lumps, persistent coughing, and blood in your stool. However, it’s best to investigate any unexpected change in the way your body works. It’s also essential to keep surveying the territory with breast self-exams, testicular self exams, a yearly physical, and regular colonoscopies after age 50 (or earlier if your family history warrants it).

Source of Information : Oreilly - Your Body Missing Manual

The Body’s Cancer Defenses

Written by Science Knowledge on 12:20 AM

Out of all the diseases that affect human beings, cancer is particularly hard to grasp. After all, bacteria and viruses had millions of years to evolve into deadly attackers. Cancer cells are just the product of a random cell gone haywire. So how can they possibly account for the second most likely cause of death in the industrialized world?

The answer is bad luck and big numbers. Although cancer-causing mutations are exceedingly rare (on an individual-cell basis), your body has trillions of cells, and it manufacturers millions more every minute. Even a seemingly miniscule rate of cancerous mutation—say, one in a million cell divisions—would guarantee you a terminal case of cancer.

The real question isn’t why we get cancer, but why we don’t get it more often. In fact, the body has countless built-in safety measures to defend against cancerous cells. It has specialized genes that detect suspicious behavior and shut down cell growth or trigger cell destruction. Your immune system even has a class of specialized warriors called natural killer cells that hunt down cancerous cells and release toxic granules that destroy them.

However, none of these mechanisms is completely foolproof, and given enough time (and enough cell mutations), a cancerous cell can start to thrive. Cancer is a particular problem in old age because the body’s cells have had more time to accumulate the right mutations, the natural cancer fighting processes of the body have weakened, and a lifetime of exposure to carcinogens (chemicals in the environment that can damage DNA and spur mutations) has taken its toll. The following chart shows the rate of colon cancer as a function of age, and it tells a clear story—cancer risks skyrocket as time wears on.

It’s all a bit ironic. In one context, sheer mind-boggling odds can turn one mutation in a trillion into the survival advantage that drives the evolution of a species. But in another, a chance combination of deadly mutations can trigger a cancer and destroy an individual.

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Cancer

Written by Science Knowledge on 12:17 AM

So far, you’ve spent most of your time exploring battles that are relatively clear-cut. They pit your body against outside forces, like invading bacteria and viruses. But now it’s time to consider a subtler enemy—rogue cells in your own body.

The disease is cancer, and it starts with a subtle genetic shift that transforms one of the trillions of ordinary cells in your body into a saboteur. Unlike the cells in the rest of your body, a cancerous cell isn’t bound by the normal rules of human life. It grows without respect for the boundaries between different types of tissue, invades other sites in the body, and refuses to die a natural death. In the end, what begins as a series of simple cellular errors can become an unstoppable process that ravages your body.


How Cancer Starts
Although we often imagine cancer as a single thing, it’s actually a family of diseases that’s characterized by misbehaving cells. The problem begins with a chance mutation in a key regulatory gene—essentially, a cell turns off one of the safeguards that restricts it or over-activates one of the mechanism that drives normal cell growth. However, a single mutation isn’t enough—if it were, you’d be riddled with cancer while you were still in diapers. Instead, cancer needs to develop through a succession of highly improbable mutations, which gradually give the cell and its offspring the ability to defeat several different control mechanisms.

The picture on the next page shows one way this process can unfold:
1. The cell begins its life as normal.

2. Random mutations give the cell the ability to ignore the normal recycling processes of your body, so instead of dying, the cell lives forever. This transformation happens quietly and without event.

3. Next, the cell multiplies, creating similar ill-tempered progeny and crowding healthy cells out of the way. This unchecked growth often creates an abnormal mass of tissue called a tumor, which can cause problems if it presses on one of your vital organs.

4. The real trouble with cancer occurs when the cancerous cells metastasize, or spread to other areas of your body. Once cancer cells have become mobile, they travel far and wide, voyaging through your blood and lymph, and starting new cancer settlements throughout your body. At this point, the odds of successful treatment dwindle quickly.

Because different cancers acquire different mutations, they vary in their virulence. The nastiest forms multiply quickly and travel aggressively, and they can rapidly colonize your body. Other forms are highly treatable and have better survival rates than a heart attack or stroke.

When diagnosing a new cancer in a patient, doctors classify how far it’s advanced by stage. The exact definition of the various stages (and the prognosis of a cancer patient) depends on the type of cancer and its location. But in general, stage I cancers have not yet spread and are usually treatable. Stage II cancers have had some time to develop but have not yet traveled the body, while stage III cancers have made it to nearby lymph nodes. Stage IV cancers are the worst— they’ve spread to organs throughout the body and are usually untreatable.

Ordinarily, cells have a built-in self-destruct sequence. When a cell detects that it’s diseased or damaged (or when other cells detect something suspicious and convince the cell that it’s not quite right), the cell initiates this self-destruct sequence and destroys itself in a calm and orderly fashion. This tidy suicide process is called apoptosis, and it’s as fundamental to the functioning of your body as cell division. However, successful cancer cells don’t obey the shutdown command— they stay alive, multiply, and can develop more dangerous mutations.

Source of Information : Oreilly - Your Body Missing Manual

What Is the Deadliest Virus?

Written by Science Knowledge on 12:01 AM

When it comes to deadly viruses, Ebola kills in the quickest and most horrific way possible— causing massive bleeding and turning internal organs into a soup of lifeless mush. It’s estimated that 90 percent of Ebola-infected people die from these symptoms. However, HIV (the virus that causes AIDS) is still more effective eventually, virtually everyone who contracts HIV will have their immune systems knocked offline, as the virus infects the very T cells that are supposed to defend the body. Without treatment, a person suffering from AIDS is unlikely to last even a few years, as hundreds of ordinarily harmless microbes ravage the body.

However, neither of these viruses can boast the highest body count through history. That dubious distinction probably belongs to influenza, the virus that causes the flu. Each year, influenza kills hundreds of thousands of people across the globe, most often the very old or the very young. But every few generations, a strain appears that is far deadlier, like the 1918 Spanish flu, which killed tens of millions of people in a single, worldwide outbreak.

Source of Information : Oreilly - Your Body Missing Manual

Profile of a Cold

Written by Science Knowledge on 11:59 PM

One type of virus that your body knows intimately is the one that causes upper respiratory tract infections, which are otherwise known as the common cold. Colds appear to expose a chink in the defenses of your immune system. After all, the average person suffers three or four colds a year, and no matter how many you endure, you’re never rewarded with lasting immunity. The reason for this endless suffering is variety. Scientists recognize more than 200 viruses that cause colds, and it’s likely that there are many more on the loose, unknown and uncataloged.

This diversity raises an obvious question: How can so many different viruses cause essentially the same symptoms when they infect you? The answer is that the symptoms of a cold aren’t caused by the virus itself, but by the inflammatory response that your body greets it with. This often starts with pain and swelling in the throat, followed by a runny nose as your body attempts to wash out virus particles. If the inflammation makes its way deeper into your throat, the next inflammatory symptom is coughing.

The odds are that you’ll spend some time this year battling at least one cold. Here are a few tips to keep in mind:

• Colds aren’t an indication of poor health. We all know someone who makes it through the year without the faintest sniffle—and someone else who spends an entire month bleary-eyed and runny-nosed. The odd truth is that both people may be catching the same cold viruses, but simply experiencing them differently. Before you envy the person who slips by with nary a symptom, remember that a laid-back immune response can allow a cold virus to spread farther and even cause damage before it’s destroyed.

• Vitamin C doesn’t help. It’s an enduring myth, but countless studies show that there’s basically no benefit to the citrus vitamin. The exception is marathon runners and people who perform strenuous exercise in the cold, where vitamin C appears to reduce the risk of catching the cold virus (but still does nothing to cure an existing cold).

• Blowing your nose can be risky. Most scientists agree that blowing your nose doesn’t provide any benefit for your body (other than comfort). However, there’s a darker side to nose blowing. As you learned when you explored nasal mucus, overly vigorous nose
blowing can drive viruses and inflammatory substances into your sinuses, possibly causing additional pain or infection.

• Colds travel through snot. You most commonly pick up the cold virus through airborne droplets of mucus (generated by someone else’s sneeze), or by touching a contaminated surface. Kids are prime transmitters, but even adults are adept at transmitting nearly invisible traces of mucus from their noses to their hands and then to everything else in the surrounding environment. However, the cold virus still needs to jump through a weak point in your body armor, such as your eyes, nose, or mouth. So after you touch any of these vulnerable places, make sure you wash your hands.

• Colds might prime your immune system. There’s no cure for the common cold on the horizon. Even if there were, you might not want to take it. Some researchers believe that a cold-free life might leave people at increased risk for allergies and asthma.

Source of Information : Oreilly - Your Body Missing Manual

You Are a Virus

Written by Science Knowledge on 11:48 PM

Not long ago, you learned that many of the basic processes of human life require a partnership between your body and the bacteria that calls it home. Now you’re ready to learn another disturbing truth: you have an even more intimate relationship with viruses.

The key players are retroviruses, a broad class of viruses that carries strands of RNA instead of DNA. The interesting and highly technical part is that your body sometimes converts RNA back into DNA. As a result, a virus that holds a piece of RNA is able to fuse itself into your genes, altering your genetic code.

Before you panic, remember that your body has trillions of cells, and virus-infected cells generally don’t last long before white blood cells destroy them. However, there’s always the possibility that a virus will find its way into a germ-line cell—in humans, these are the cells that produce male sperm and female egg. If a virus lands in one of these cells, it has a good shot at being incorporated into the genes of the next generation. And that’s not science fiction, as recent studies suggest that nearly 10 percent of human DNA consists of pasted-in viruses from the past.

Now, it’s important to understand that a virus integrated this way probably isn’t going to infect newly minted babies. That’s because the virus incorporates its DNA in a random place. Usually, it’s in the vast wasteland called junk DNA—segments of your genetic code that don’t appear to do anything at all. However, occasionally a virus lands somewhere important, and the result is usually trouble. Some researchers believe hemophilia and muscular dystrophy are two genetic diseases that cropped up when random, viral DNA blundered into the wrong spot.

Finally, here’s the really interesting part: As you probably know, evolution works when apparently random changes in a creature’s DNA give it a valuable survival advantage. And while viral DNA is more likely to cause a problem than to confer a benefit (and is most likely to do nothing at all), every once in a while a bit gets into a place where it just might do real good. In fact, many scientists believe that viruses have helped shape evolution on our planet by reshuffling genes, pasting in their own contributions, and carrying genes from one species to another. So while life started as mere bacteria, viruses just might have supplied some of the variety that drove evolution forward and led, eventually, to the creation of you.

Source of Information : Oreilly - Your Body Missing Manual

The Life Cycle of a Virus

Written by Science Knowledge on 11:45 PM

To do anything, a virus needs your help. First, it needs to get into your body, and it does that in much the same way as bacteria does—by being inhaled into your lungs, swallowed into your digestive tract, or absorbed through a cut in your skin.

Once inside your body, the virus drifts aimlessly until it comes into contact with the right cell—one that has a coat of proteins that complements those of the virus. When the virus bumps up against this cell, its proteins lock on. (Keep in mind this isn’t a conscious decision for the virus—it’s simply a reaction caused by the fact that it fits the target cell like a fuzzy sweater and a strip of Velcro.)

What happens next is more unsettling. The virus launches the multiple steps of its attack procedure. First, the virus needs to get inside the cell. In some cases, the cell may engulf the virus in the same way that it swallows tiny nutrients, pulling it in. Or the virus may inject its genetic material through the cell wall. Either way, the damage is done. The foreign genetic material finds its way deep into the cell’s working parts, where it quickly takes over.

In the classic case, the virus inserts a short snippet of DNA into the target cell (as shown in step 1 of the figure on page 221). Like all strands of DNA , this DNA contains instructions for building specialized proteins. The target cell cheerily follows these instructions, unaware that it’s helping the enemy.

Once built, these proteins begin to carry out their pre-programmed functions manufacturing thousands of new viruses. (This is what happens in step 2 and step 3.) In this way, the virus hijacks the inner workings of the cell, like a pirate commandeering an ocean liner. But all the while, the virus hasn’t actively done a single thing. It’s just a set of malicious instructions that your body executes, simply because the virus was in the right place at the right time.

Once they’ve taken over a cell, most viruses replicate like Viagra-fuelled rabbits. Eventually, they leak out of the cell through tiny pores or blow it apart like an overfilled water balloon (as you can see in step 4).

There’s a virus for virtually every type of cell. Viruses infect animals, plants, and even bacteria. (In fact, it’s likely that the bacteria that causes cholera would be completely harmless were it not for the presence of a toxinproducing virus embedded inside.) However, the viruses that affect one species are often unable to affect another, or they may have dramatically different effects. HIV is a well-known example—not only is it unable to infect other animals, but the related SIV strains that affect monkeys and chimpanzees rarely cause the compromised immune system and debilitating symptoms of AIDS.

Viruses don’t necessarily correspond to illnesses. In fact, many viruses have no symptoms. They don’t destroy their host cells, reproduce very quickly, or create poisonous compounds. Virtually all people have at least a few harmless viral passengers hiding in their bodies.

Source of Information : Oreilly - Your Body Missing Manual

Viruses

Written by Science Knowledge on 11:40 PM

In some respects, the battle between bacteria and your body is refreshingly straightforward. Huge armies of microscopic, foreign creatures flood your body. They wreak havoc—briefly—before your better-armed defensive forces destroy them.

Viruses are a different matter. First, they’re much tinier— about a hundredth the size of
an average bacterium. In fact, viruses are so vanishingly small that even the most powerful optical microscope can’t spot one (although a cutting-edge electron microscope can). Stack viruses and bacteria together, and it’s like comparing a toddler to a brontosaurus.

To get a better feel for the difference in scale, check out www.cellsalive.com/howbig.htm. There you’ll see a simple animation that places you on the head of a pin and increases the magnification until you can spot a dust mite, a particle of pollen, and a red blood cell. Zoom in still more and you’ll be able to make out the much smaller cell of a bacterium, and then, finally, a virus.

There’s another clear difference between bacteria and viruses, but you need to step into their microscopic world to see it. Up close, a bacterium looks like a tiny alien being. It may be small (and ugly), but it’s full of life— feeding, reproducing, and generating energy with some of the same processes your own cells use. Many bacteria are even able to move by propelling themselves with long, whip-like tails, or by gliding along paths of self-produced slime.

By comparison, a virus looks more like a piece of organic debris. Its structure is simple—in fact, a virus consists of little more than a submicroscopic scrap of genetic material (either DNA or its relative, RNA) wrapped in a thin coat of protective protein. On its own, a virus is silent, inert, and completely lifeless. It’s unable to power a single one of the chemical reactions required for life.

If it weren’t for the presence of other life-forms, this is where the story would end. But as you’ll see, viruses have the uncanny ability to turn up at the right place at the right time—namely, in the midst of a normal cell’s manufacturing process.

The lifelessness of viruses makes them dangerous in another way. Because they don’t live on their own, they’re in little danger of dying naturally. In other words, they won’t run out of fuel or burn out from the hard work of cellular life. In fact, some viruses (like anthrax) can linger for years in the outside world. Others can sleep inside their hosts, waiting for the right trigger before they become active.

Source of Information : Oreilly - Your Body Missing Manual

Can You Taste Spoiled Foods?

Written by Science Knowledge on 11:37 PM

E. coli and other food-borne bacteria (like salmonella and campylobacter) are tasteless. Contaminated food gives no obvious sign of the single-celled organisms that lurk there, waiting to colonize your body. This raises an excellent question: If dangerous bacteria don’t leave obvious signs, what’s making that week-old package of ground beef smell so bad?

The answer is spoilage bacteria, a family of bacteria that thrives on just about any food. As these bacteria replicate, they coat your food with slime. The waste products they leave behind cause the objectionable changes in smell and taste. However, for all their obvious repulsiveness, eating them probably won’t make you sick. That’s because spoilage bacteria is ideally suited to the world of decaying grocery produce, not the high acid environment of your stomach.

So does this mean that you can add rotten food to your dinner table without harm? Well, not quite. As spoilage bacteria break down food, other organisms hitch a ride. Molds quickly join the party (for example, the fuzzy green fur on forgotten salami). Some are dangerous and create poisonous substances that permeate food, and they remain even after cooking.

Furthermore, if conditions are ideal for spoilage bacteria, it’s a safe bet that they’re good for pathogenic bacteria, too. In other words, if your food is spoiled, it’s also more likely to hold a teeming population of pathogenic bacteria, and therefore to pose a greater health risk.

Source of Information : Oreilly - Your Body Missing Manual

Antibiotics

Written by Science Knowledge on 11:35 PM

The standard way to combat a bacterial infection is with antibiotics, a class of chemicals that kills bacteria. Although we group them into a single category, different antibiotics work in different ways. Some destroy the bacteria’s cell walls, causing them to burst and die. Others disrupt the processes bacterial colonies use to reproduce. Either way, the basic principle is the same—antibiotic drugs interfere with the machinery of bacterial life without affecting the way human cells operate.

Just as antibiotics have no effect on human cells, they also leave viruses, parasites, and fungal infections untouched. You’ll need different types of drugs to battle these attackers—antibiotics will have no effect. And in the case of viruses, you’ll usually be forced to wait and suffer until your immune system ramps up its defenses. (That’s why a trip to the doctor’s office won’t help you cure the average cold or flu.)

Some antibiotics work against certain families of bacteria and are called narrow-spectrum antibiotics. Others destroy wide swaths of bacterial life and are called broad-spectrum antibiotics. But neither sort can distinguish between the bacteria that harm your body and those you’d like to keep. When antibiotics wipe out the beneficial bacteria in your colon and on your skin, they often lead to side effects like diarrhea and fungal infections of the mouth, digestive tract, and vagina.

A more serious problem is antibiotic resistance—the ability of bacteria to evolve immunity to commonly prescribed antibiotics. Antibiotic resistance usually occurs when a colony of bacteria meets up with antibiotic drugs. Although these antibiotics destroy virtually all the bacteria—and they do it quickly—they may leave behind a few rare mutants that have some level of natural immunity. If the antibiotic attack keeps up, these mutants will eventually die along with their weaker relatives. But if the onslaught ends, these mutants will have a chance to establish a new, more resistant colony. Repeat the process a few times, and you’ll gradually breed stronger and more resistant bacteria. And throw in a few different types of antibiotics, and you just might produce a superbug that’s impervious to all forms of standard treatment. Even worse, bacteria have a naughty habit of swapping DNA, which means the antibiotic resistance that develops in one species can leap to another, more virulent strain.

Now that you understand antibiotic resistance, you know why your pharmacist always tells you to finish the full course of your antibiotic prescription. If you have an infection, most antibiotics will destroy the large majority of bacteria in just a couple of days. But if you stop at that point, you may spare a few, resilient stragglers. And like the son who avenges the father in a cult karate movie, those bacterial stragglers just might come back to wreak some serious havoc in your body or someone else’s.

Another way to help prevent antibiotic resistance is to avoid using products that contain unnecessary antibacterial chemicals. The best example is antibacterial soap, a mostly useless product that’s debunked.

Source of Information : Oreilly - Your Body Missing Manual

Is Raw Cookie Dough a Killer?

Written by Science Knowledge on 11:00 PM

For many, baking cookies is a labor of love that’s sweetened by the occasional stealthy scoop of raw cookie dough. But there’s a sinister side to this guilty pleasure: Public health officials warn that raw eggs can contain stomach-churning salmonella bacteria, which can cause fever, diarrhea, and even death. So should cookie bakers keep their fingers to themselves?

First, it’s important to realize that no one really knows how many eggs are contaminated with salmonella. In the past, experts thought that salmonella lived on eggshells, but couldn’t make its way into an egg without traveling through a hairline crack. Today we know that salmonella can pass from the ovaries of infected hens straight into their developing eggs.

In the Northeastern states of the U.S., solid estimates suggest that 1 in 10,000 eggs are contaminated with salmonella. That means you could eat an entire batch of two-egg cookie dough and face only a 0.02 percent chance of a night on the toilet. Of course, these figures are only estimates—some studies put the number of infected eggs at 1 in 20,000, while at least one ratchets it up to 1 in 700.

Even then, tainted dough may not be as dangerous as it seems. Studies show that salmonella needs the power of numbers to wreak its damage, and healthy volunteers don’t get a serious infection unless they ingest about 1 million salmonella organisms. (This is notably different from dangerous strains of E. coli, which can breach your body’s defenses in very small numbers—as few as 200 bacteria.) And if you do get infected with salmonella, the odds are overwhelming that you’ll be back on your feet in a week with nothing worse than some painful memories.

The bottom line? Eating raw cookie dough is particularly risky for young children, pregnant women, the elderly, and people with impaired immune systems—all of whom are more likely to suffer dangerous complications. (And to be consistently paranoid about egg safety, none of these individuals should eat a runny-yoked egg, which may still harbor bacteria.) But an average, healthy adult with a normally functioning immune system has a relatively small risk of serious health trouble. On the other hand, exercise caution when dealing with foods that traditionally use raw eggs—such as Caesar salad dressing, eggnog, and homemade ice cream. These foods aren’t eaten immediately, which gives bacteria time to multiply and reach more dangerous levels. To keep these foods safe, make them with pasteurized egg products.

Source of Information : Oreilly - Your Body Missing Manual

Nano-Size Germ Killers

Written by Science Knowledge on 10:53 PM

Tiny knives could be important weapons against superbugs

Drug-resistant tuberculosis is roaring through Europe, according to the World Health Organization. Treatment options are few—antibiotics do not work on these highly evolved strains—and about 50 percent of people who contract the disease will die from it. The grim situation mirrors the fight against other drug-resistant diseases such as MRSA, a staph infection that claims 19,000 lives in the U.S. every year. Hope comes in the form of a nanotech knife. Scientists working at IBM Research– Almaden have designed a nanoparticle capable of utterly destroying bacterial cells by piercing their membranes.

The nanoparticles’ shells have a positive charge, which binds them to negatively charged bacterial membranes. “The particle comes in, attaches, and turns itself inside out and drills into the membrane,” says Jim Hedrick, an IBM materials scientist working on the project with collaborators at Singapore’s Institute of Bioengineering and Nanotechnology. Without anintact membrane, the bacterium shrivels away like a punctured balloon. The nanoparticles are harmless to humans—they do not touch red blood cells, for instance—because human cell membranes do not have the same electrical charge that bacterial membranes do. After the nanostructures have done their job, enzymes break them down, and the body flushes them out.

Hedrick hopes to see human trials of the nanoparticles in the next few years. If the approach holds up, doctors could squirt nanoparticle-infused gels and lotions onto hospital patients’ skin, warding off MRSA infections. Or workers could inject the particles into the bloodstream to halt systemic drug-resistant organisms, such as streptococci, which can cause sepsis and death. Even if it succeeds, such a treatment would have to overcome any unease over the idea of nanotech drills in the bloodstream. But the nastiest bacteria on the planet won’t succumb easily.

Source of Information : Scientific American Magazine 

Crops That Don’t Need Replanting

Written by Science Knowledge on 10:50 PM

Year-round crops can stabilize the soil and increase yields. They may even fight climate change

Before agriculture, most of the planet was covered with plants that lived year after year. These perennials were gradually replaced by food crops that have to be replanted every year. Now scientists are contemplating reversing this shift by creating perennial versions of familiar crops such as corn and wheat. If they are successful, yields on farmland in some of the world’s most desperately poor places could soar. The plants might also soak up some of the excess carbon in the earth’s atmosphere.

Agricultural scientists have dreamed of replacing annuals with equivalent perennials for decades, but the genetic technology needed to make it happen has appeared only in the past 10 or 15 years, says agroecologist Jerry Glover. Perennials have numerous advantages over crops that must be replanted every year: their deep roots prevent erosion, which helps soil hold onto critical minerals such as phosphorus, and they require less fertilizer and water than annuals do. Whereas conventionally grown monocrops are a source of atmospheric carbon, land planted with perennials does not require tilling, turning it into a carbon sink. Farmers in Malawi are already getting radically higher yields by planting rows of perennial pigeon peas between rows of their usual staple, corn. The peas are a much needed source of protein for subsistence farmers, but the legumes also increase soil water retention and double soil carbon and nitrogen content without reducing the yield of the primary crop on a given plot of land.

Taking perennials to the next level—adopting them on the scale of conventional crops—will require a significant scientific effort, however. Ed Buckler, a plant geneticist at Cornell University who plans to develop a perennial version of corn, thinks it will take five years to identify the genes responsible for the trait and another decade to breed a viable strain. “Even using the highest-technology approaches available, you’re talking almost certainly 20 years from now for perennial maize,” Glover says. Scientists have been accelerating the development of perennials by using advanced genotyping technology. They can now quickly analyze the genomes of plants with desirable traits to search for associations between genes and those traits. When a first generation of plants produces seeds, researchers sequence young plants directly to find the handful out of thousands that retain those traits (rather than waiting for them to grow to adulthood, which can take years).

Once perennial alternatives to annual crops are available, rolling them out could have a big impact on carbon emissions. The key is their root systems, which would sequester, in each cubic meter of topsoil, an amount of carbon equivalent to 1 percent of the mass of that dirt. Douglas Kell, chief executive of the U.K.’s Biotechnology and Biological Sciences Research Council, has calculated that replacing 2 percent of the world’s annual crops with perennials each year could remove enough carbon to halt the increase in atmospheric carbon dioxide. Converting all of the planet’s farmland to perennials would sequester the equivalent of 118 parts per million of carbon dioxide— enough, in other words, to pull the concentration of atmospheric greenhouse gases back to preindustrial levels.

Source of Information : Scientific American Magazine 

Microbe Miners

Written by Science Knowledge on 10:44 PM

Bacteria extract metals and clean up the mess afterward

Mining hasn’t changed much since the Bronze Age: to extract valuable metal from an ore, apply heat and a chemical agent such as charcoal. But this technique requires a lot of energy, which means that it is too expensive for ores with lower metal concentrations.

Miners are increasingly turning to bacteria that can extract metals from such low-grade ores, cheaply and at ambient temperatures. Using the bacteria, a mining firm can extract up to 85 percent of a metal from ores with a metal concentration of less than 1 percent by simply seeding a waste heap with microbes and irrigating it with diluted acid. Inside the heap Acidithiobacillus or Leptospirillum bacteria oxidize iron and sulfur for energy. As they eat, they generate reactive ferric iron and sulfuric acid, which degrade rocky materials and free the valued metal.

Biological techniques are also being used to clean up acidic runoff from old mines, extracting a few last precious bits of metal in the process. Bacteria such as Desulfovibrio and Desulfotomaculum neutralize acids and create sulfides that bond to copper, nickel and other metals, pulling them out of solution.

Biomining has seen unprecedented growth in recent years as a result of the in-creasing scarcity of high-grade ores. Nearly 20 percent of the world’s copper comes from biomining, and production has doubled since the mid-1990s, estimates mining consultant Corale Brierley. “What mining companies used to throw away is what we call ore today,” Brierley says. The next step is unleashing bacterial janitors on mine waste. David Barrie Johnson, who researches biological solutions to acid mine drainage at Bangor University in Wales, estimates that it will take 20 years before bacterial mine cleanup will pay for itself. “As the world moves on to a less carbon-dependent society, we have to look for ways of doing things that are less energy-demanding and more natural,” Johnson says. “That’s the long-term objective, and things are starting to move nicely in that direction.”

Source of Information : Scientific American Magazine 

Currency without Borders

Written by Science Knowledge on 10:33 PM

The world’s first digital currency cuts out the middleman and keeps users anonymous

Imagine if you were to walk into a deli, order a club sandwich, throw some dollar bills down and have the cashier say to you, “That’s great. All I need now is your name, billing address, telephone number, mother’s maiden name, and bank account number.” Most customers would balk at these demands, and yet this is precisely how everyone pays for goods and services over the Internet.

There is no currency on the Web that is as straightforward and anonymous as the dollar bill. Instead we rely on financial surrogates such as credit-card companies to handle our transactions (which pocket a percentage of the sale, as well as your personal information). That could change with the rise of Bitcoin, an all-digital currency that is as liquid and anonymous as cash. It’s “as if you were taking a dollar bill, squishing it into your computer and sending it out over the Internet,” says Gavin Andresen, one of the leaders of the Bitcoin network.

Bitcoins are bits—strings of code that can be transferred from one user to another over a peer-to-peer network. Whereas most strings of bits can be copied ad infinitum (a property that would render any currency worthless), users can spend a Bitcoin only once. Strong cryptography protects Bitcoins against would-be thieves, and the peer-to-peer network eliminates the need for a central gatekeeper such as Visa or PayPal. The system puts power in the hands of the users, not financial middlemen.

Bitcoin borrows concepts from well-known cryptography programs. The software assigns every Bitcoin user two unique codes: a private key that is hidden on the user’s computer and a public address that everyone can see. The key and the address are mathematically linked, but figuring out someone’s key from his or her address is practically impossible. If I own 50 Bitcoins and want to transfer them to a friend, the software combines my key with my friend’s address. Other people on the network use the relation between my public address and private key to verify that I own the Bitcoins that I want to spend, then transfer those Bitcoins using a code-breaking algorithm. The first computer to complete the calculations is awarded a few Bitcoins now and then, which recruits a diverse collective of users to maintain the system.

The first reported Bitcoin purchase was pizza sold for 10,000 Bitcoins in early 2010. Since then, exchange rates between Bitcoin and the U.S. dollar have bounced all over the scale like notes in a jazz solo. Because of the currency’s volatility, only the rare online merchant will accept payment in Bitcoins. At this point, the Bitcoin community is small but especially enthusiastic— just like the early adopters of the Internet.

Source of Information : Scientific American Magazine 

A Circuit in Every Cell

Written by Science Knowledge on 9:53 PM

Progress for tiny biocomputers

Researchers in nanomedicine have long dreamed of an age when molecular-scale computing devices could be embedded in our bodies to monitor health and treat diseases before they progress. The advantage of such computers, which would be made of biological materials, would lie in their ability to speak the biochemical language of life.

Several research groups have recently reported progress in this field. A team at the California Institute of Technology, writing in the journal Science, made use of DNA nanostructures called seesaw gates to construct logic circuits analogous to those used in microprocessors. Just as siliconbased components use electric current to represent 1’s and 0’s, bio-based circuits use concentrations of DNA molecules in a test tube. When new DNA strands are added to the test tube as “input,” the solution undergoes a cascade of chemical interactions to release different DNA strands as “output.” In theory, the input could be a molecular indicator of a disease, and the output could be an appropriate therapeutic molecule.

A common problem in constructing a computer in a test tube is that it is hard to control which interactions among molecules occur. The brilliance of the seesaw gate is that a particular gate responds only to particular input DNA strands. In a subsequent Nature paper, the Caltech researchers showed off the power of their technique by building a DNAbased circuit that could play a simple memory game. A circuit with memory could, if integrated into living cells, recognize and treat complex diseases based on a series of biological clues.

This circuitry has not been integrated into living tissue, however, in part because its ability to communicate with cells is limited. Zhen Xie of the Massachusetts Institute of Technology and his collaborators have recently made progress on this front. As they reported in Science, they designed an RNAbased circuit that was simpler but could still distinguish modified cancer cells from noncancerous cells and, more important, trigger the cancer cells to self-destruct. Both techniques have been used only in artificial scenarios. Yet the advances in DNA-based circuits offer a new, powerful platform to potentially realize researchers’ long-held biocomputing dreams.

Source of Information : Scientific American Magazine 

Microwaves and the Speed of Light

Written by Science Knowledge on 9:49 PM

New physics tricks for the most underestimated of kitchen appliances

You can find a microwave oven in nearly any American kitchen— indeed, it is the one truly modern cooking tool that is commonly at hand—yet these versatile gadgets are woefully underestimated. Few see any culinary action more sophisticated than reheating leftovers or popping popcorn. That is a shame because a microwave oven, when used properly, can cook certain kinds of food perfectly, every time. You can even use it to calculate a fundamental physical constant of the universe. Try that with a gas burner.

To get the most out of your microwave, it helps to understand that it cooks with light waves, much like a grill does, except that the light waves are almost five inches (12.2 centimeters) from peak to peak—a good bit longer in wavelength than the infrared rays that coals put out. The microwaves are tuned to a frequency (2.45 gigahertz, usually) to which molecules of water and, to a lesser extent, fat resonate.

The water and oil in the exterior inch or so of food soaks up the microwave energy and turns it into heat; the surrounding air, dishes and walls of the oven do not. The rays do not penetrate far, so trying to cook a whole roast in a microwave is a recipe for disaster. But a thin fish is another story. The cooks in our research kitchen found a fantastic way to make tilapia in the microwave. Sprinkle some sliced scallions and ginger, with a
splash of rice wine, over a whole fish, cover it tightly with plastic wrap and microwave it for six minutes at a power of 600 watts. (Finish it off with a drizzle of hot peanut oil, soy sauce and sesame oil.)

The cooking at 600 W is what throws many chefs. To heat at a given wattage, check the power rating on the back of the oven (800 W is typical) and then multiply that figure by the power setting (which is given either as a percentage or in numbers from one to 10 representing 10 percent steps). A 1,000-W oven, for example, produces 600 W at a power setting of 60 percent (or “6”). To “fry” parsley brushed with oil, cook it at 600 W for about four minutes. To dry strips of marinated beef into jerky, cook at 400 W for five minutes, flipping the strips once a minute.

If you are up for slightly more math, you can perform a kitchen experiment that
Albert Einstein would have loved: prove that light really does zip along at almost 300 million meters per second. Cover a cardboard disk from a frozen pizza with slices of Velveeta and microwave it at low power until several melted spots appear. (You don’t want it rotating, so if your oven has a carousel, prop the cardboard
above it.) Measure the distance (in meters) between the centers of the spots. That distance is half the wavelength of the light, so if you double it and multiply by 2.45 billion (the frequency in cycles per second), the result is the velocity of the rays bouncing about in your oven.

Source of Information : Scientific American Magazine 

How to See the Invisible

Written by Science Knowledge on 11:33 AM

Augumented-reality apps uncover the hidden reality all around you

Everybody’s amazed by touch-screen phones. They’re so thin, so powerful, so beautiful! But this revolution is just getting under way. Can you imagine what these phones will be like in 20 years? Today’s iPhones and Android phones will seem like the Commodore 64. “Why, when I was your age,” we’ll tell our grandchildren, “phones were a third of an inch thick!” Then there are the apps. Right now we’re all delighted to do simple things on our phones, like watch videos and play games. But the ingredients in the modern app phone—camera, GPS, compass, accelerometer, gyroscope, Internet connection—make it the perfect device for the next wave of software. Get ready for augmented reality (AR). That term usually refers to a live-camera view with superimposed informational graphics. The phone becomes a magic looking glass, identifying physical objects in the world around you.

If you’re color-blind like me, then apps like Say Color or Color ID represent a classic example of what augmented reality can do. You hold up the phone to a piece of clothing or a paint swatch—and it tells you by name what color the object is, like dark green or vivid red. You’ve gone to your last party wearing mismatched clothes.

Other apps change what you see. When a reader sent me a link to a YouTube video promoting Word Lens, I wrote back, “Ha-ha, very funny.” It looked so magical, I thought it was fake. But it’s not. You point the iPhone’s camera at a sign or headline in Spanish. The app magically replaces the original text with an English translation, right there in the video image in real time—same angle, color, background material, lighting. Somehow the app erases the original text and replaces it with new lettering. (There’s an English-to-Spanish mode, too.) Some of the most promising AR apps are meant to help you when you’re out and about. Apps like New York Nearest Subway and Metro AR let you look down at the ground and see colorful arrows that show you which subway lines are underneath your feet. Raise the phone perpendicular to the ground, and you’ll see signs for the subway stations—how far away they are and which subway lines they serve. When you’re in a big city, apps like Layar and Wikitude let you peer through the phone at the world around you. They overlay icons for information of your choice: real estate listings, ATM locations, places with Wikipedia entries, public works of art, and so on. Layar boasts thousands of such overlays.

There are AR apps that show you where the hazards are on golf courses (Golfscape GPS Rangefinder), where you parked your car (Augmented Car Finder), who’s using Twitter in the buildings around you (Tweet360), what houses are for sale near you and for how much (ZipRealty Real Estate), how good and how expensive a restaurant is before you even go inside (Yelp), the names of the stars and constellations over your head (Star Walk, Star Chart), the names and details of the mountains in front of you (Panoramascope, Peaks), what crimes have recently been committed in the neighborhoods around you (SpotCrime), and dozens more. Several of these apps are not, ahem, paragons of software stability. And many, like Layar, are pointless outside of big cities because there aren’t enough data points to overlay.

As much fun as they are to use, AR apps mean walking through your environment with your eyes on your phone, held at arm’s length—a posture with unfortunate implications for social interaction, serendipitous discovery and avoiding bus traffic. Furthermore, there’s already been much bemoaning of our society’s decreasing reliance on memory; in the age of Google, nobody needs to learn the presidents, the state capitals or the periodic table. AR apps are only going to make things worse. Next thing you know, AR apps will identify our friends using facial recognition. Can’t you just see it? You’ll be at a party, and someone will come up to you and say, “Hey, how are you—” (consulting the phone) “—David?” But every new technology has its rough edges, and somehow we muddle through. Someday we will boggle our grandchildren’s minds with tales of life before AR—if we can remember their names.

Source of Information : Scientific American Magazine

Yawn of the Tortoise

Written by Science Knowledge on 11:19 AM

Sleepiness and boredom aren’t always contagious

The following post is from a series about the annual Ig Nobel Prizes in science, which
honor “achievements that first make people laugh and then make them think.” They were awarded in September in Cambridge, Mass.

Now we come to the Ig Nobel Physiology Prize. Yawns are notoriously contagious in humans and in other social animals, especially primates. In humans, yawning has been thought to do various things, including cooling the brain, increasing arousal when you’re sleepy and, possibly, helping to synchronize group behavior.

Could yawning be a form of unconscious empathy? This would mean that in order to have a contagious yawn, the animals involved would have to be capable of empathy, of fellow feeling. We know that dogs and primates, and humans, probably are, but that means we can’t really test for whether it’s empathy or not. We need a species that is social but probably can’t feel for its compatriots.

That’s where tortoises come in. To test whether yawning requires empathy and thus get at the real purpose that yawning might serve, Anna Wilkinson of the University of Lincoln in England and her colleagues took a group of redfooted tortoises that lived together and trained one of them to yawn when exposed to a red square. Then they had tortoises watch the trained tortoise in action and checked them for yawns. The researchers also checked for yawns when no other tortoise was present and when the trained tortoise had no red square and so wasn’t yawning.

What they got was a big, fat negative. The test tortoises showed no notice of the other animals’ huge yawns. This may mean that contagious yawning is not just the result of a fixed-action pattern triggered when you see someone else yawn. If that were the case, the tortoises would have yawned right along with their compatriots. Contagious social yawning may require something more, a social sense or a sense of empathy resulting from complex social interactions. Of course, it could also mean that tortoises are just a really bad choice for contagious yawning. But the social explanation seems a little more supported.

Source of Information : Scientific American Magazine

Freedom Fighter

Written by Science Knowledge on 11:16 AM

Which side was Steve Jobs on?

In 1977, 22-year-old Steve Jobs introduced the world to one of the first self-contained personal computers, the Apple II. The machine was a bold departure from previous products built to perform specific tasks: turn it on, and there was only a blinking cursor awaiting further instruction. Some owners were inspired to program the machines themselves, but others could load up software written and shared or sold by others more skilled or inspired.

Later, when Apple’s early lead in the industry gave way to IBM, Jobs and company fought back with the now classic Super Bowl advertisement promising a break from the alleged Orwellian ubiquity of Big Blue. “Unless Apple does it, no one will be able to innovate except IBM,” said Jobs’s handpicked CEO John Sculley.

In 1984 Jobs delivered the Macintosh. The blinking cursor was gone. Unlike prior PCs, the Mac was useful even without adding software. Turn it on, and the first thing it did, literally, was smile.

Under this friendly exterior, the Mac retained the essence of the Apple II and the IBM PCs: outside developers could write software and share it directly with users.

The rise of the Internet brought a new dimension to this openness. Users could run new code within seconds of encountering it online. This was deeply empowering but also profoundly dangerous. The cacophony of available code began to include viruses and spyware that can ruin a PC—or make the experience of using one so miserable that alternatives seem attractive. Jobs’s third big new product introduction came 30 years after his first. It paid homage to both fashion and fear. The iPhone, unveiled in 2007, did for mobile phones what the Mac did for PCs and the iPod did for MP3 players, setting a new standard for ease of use, elegance and cool. But the iPhone dropped the fundamental feature of openness.

Outsiders could not program it. “We define everything that is on the phone,” Jobs said. “You don’t want your phone to be like a PC. The last thing you want is to have loaded three apps on your phone, and then you go to make a call and it doesn’t work anymore.” Being closed to outsiders made the iPhone reliable and predictable. In that first year those who dared hack the phone to add features or to make it compatible with providers other than AT&T risked having it “bricked”—completely and permanently disabled— on the next automatic update from Apple. It was a far cry from the Apple II’s ethos, and it raised objections.

Jobs answered his critics with the App Store in 2008. Outside coders were welcomed
back, and thousands of apps followed. But new software has to go through Apple, which takes a 30 percent cut, along with 30 percent of new content sales such as magazine subscriptions. Apple reserves the right to kill any app or content it doesn’t like. No more surprises.

As goes the iPhone, so perhaps goes the world. The nerds of today are coding for cool but tethered gizmos, like the iPhone, and Web 2.0 platforms, like Facebook and Google Apps—attractive all, but controlled by their makers in a way even the famously proprietary Bill Gates never achieved with Windows. Thanks to iCloud and other services, the choice of a phone or tablet today may lock a consumer into a branded silo, making it hard for him or her to do what Apple long importuned potential customers to do: switch. Such walled gardens can eliminate what we now take for granted and what Jobs originally represented: a world in which mainstream technology can be influenced, even revolutionized, out of left field and without intermediation.

Today control increasingly rests with the legislators and judges who discipline platform makers. Enterprising law-enforcement officers with a warrant can flick a distant switch and turn a standard mobile phone into a roving mic or eavesdrop on occupants of cars
equipped with travel assistance systems. These opportunities are arising not only in places under the rule of law but also in authoritarian states. Curtailing abuse will require borrowing and adapting some of the tools of the hidebound, consumer-centric culture that many who love the Internet seek to supplant. A free Net may depend on some wisely developed and implemented locks and a community ethos that secures the keys to those locks among groups with shared norms and a sense of public purpose rather than in the hands of one gatekeeper.

In time, the brand names may change; Android may tighten up its control of outside code, and Apple could ease up a little. Yet the core battle between the freedom of openness and the safety of the walled garden will remain. It will be fought through information appliances that are not just products but also services, updated through a network by the constant dictates of their makers. Jobs, it seems, left his mark on both sides on the tugof war over Internet openness.

Source of Information : Scientific American Magazine

Fluid Dynamics in a Cup

Written by Science Knowledge on 11:09 AM

Scientists puzzle out when and why coffee spills

At a recent math conference, Rouslan Krechetnikov watched his colleagues gingerly carry cups of coffee. Why, he wondered, did the coffee sometimes spill and sometimes not? A research project was born.

Although the problem of why coffee spills might seem trivial, it actually brings together a variety of fundamental scientific issues. These include fluid mechanics, the stability of fluid surfaces, interactions between fluids and structures, and the complex biology of walking, explains Krechetnikov, a fluid dynamicist at the University of California, Santa Barbara.

In experiments, he and a graduate student monitored high-speed video of the complex motions of coffee-filled cups people carried, investigating the effects of walking speed and variability among those individuals. Using a frame-by-frame analysis, the researchers found that after people reached their desired walking speed, motions of the cup consisted of large, regular oscillations caused by walking, as well as smaller, irregular and more frequent motions caused by fluctuations from stride to stride, and environmental factors such as uneven floors and distractions.

Coffee spilling depends in large part on the natural oscillation frequency of the beverage—that is, the rate at which it prefers to oscillate, much as every pendulum swings at a precise frequency given its length and the gravitational pull it experiences. When the frequency of the large, regular motions that a cuppa joe experiences is comparable to this natural oscillation frequency, a state of resonance develops: the oscillations reinforce one another, much as pushing on a playground swing at the right point makes it go higher and higher, and the chances of coffee sloshing its way over the edge rise. The small, irregular movements a cup sees can also amplify liquid motion and thus spilling. These findings were to be detailed at a November meeting of the American Physical Society in Baltimore.

Once the key relations between coffee motion and human behavior are understood, it might be possible to develop strategies to control spilling, “such as using a flexible container to act as a sloshing absorber,” Krechetnikov says. A series of rings arranged up and down the inner wall of a container might also impede the liquid oscillations.

Source of Information : Scientific American Magazine

Vitamins, Minerals and MicroRNA

Written by Science Knowledge on 11:07 AM

The food we eat may control our genes

“You are what you eat.” The old adage has for decades weighed on the minds of consumers who fret over responsible food choices. Yet what if it was literally true? What if material from our food actually made its way into the innermost control centers of our cells, taking charge of fundamental gene expression?

That is in fact what happens, according to a recent study of plant-animal microRNA transfer led by Chen-Yu Zhang of Nanjing University in China. MicroRNAs are short sequences of nucleotides—the building blocks of genetic material. Although microRNAs do not code for proteins, they prevent specific genes from giving rise to the proteins they encode. Blood samples from 21 volunteers were tested for the presence of microRNAs from crop plants, such as rice, wheat, potatoes and cabbage.

The results, published in the journal Cell Research, showed that the subjects’ bloodstream contained approximately 30 different microRNAs from commonly eaten plants. It appears that they can also alter cell function: a specific rice microRNA was shown to bind to and inhibit the activity of receptors controlling the removal of LDL—“bad” cholesterol—from the bloodstream. Like vitamins and minerals, microRNA may represent a previously unrecognized type of functional molecule obtained from food.

The revelation that plant microRNAs play a role in controlling human physiology highlights the fact that our bodies are highly integrated ecosystems. Zhang says the findings may also illuminate our understanding of co-evolution, a process in which genetic changes in one species trigger changes in another. For example, our ability to digest the lactose in milk after infancy arose after we domesticated cattle. Could the plants we cultivated have altered us as well? Zhang’s study is another reminder that nothing in nature exists in isolation.

Source of Information : Scientific American Magazine

Microwaves and the Speed of Light

Written by Science Knowledge on 11:01 AM

New physics tricks for the most underestimated of kitchen appliances

You can find a microwave oven in nearly any American kitchen— indeed, it is the one truly modern cooking tool that is commonly at hand—yet these versatile gadgets are woefully underestimated. Few see any culinary action more sophisticated than reheating leftovers or popping popcorn. That is a shame because a microwave oven, when used properly, can cook certain kinds of food perfectly, every time. You can even use it to calculate a fundamental physical constant of the universe. Try that with a gas burner.

To get the most out of your microwave, it helps to understand that it cooks with light waves, much like a grill does, except that the light waves are almost five inches (12.2 centimeters) from peak to peak—a good bit longer in wavelength than the infrared rays that coals put out. The microwaves are tuned to a frequency (2.45 gigahertz, usually) to which molecules of water and, to a lesser extent, fat resonate.

The water and oil in the exterior inch or so of food soaks up the microwave energy and turns it into heat; the surrounding air, dishes and walls of the oven do not. The rays do not penetrate far, so trying to cook a whole roast in a microwave is a recipe for disaster. But a thin fish is another story. The cooks in our research kitchen found a fantastic way to make tilapia in the microwave. Sprinkle some sliced scallions and ginger, with a splash of rice wine, over a whole fish, cover it tightly with plastic wrap and microwave it for six minutes at a power of 600 watts. (Finish it off with a drizzle of hot peanut oil, soy sauce and sesame oil.)

The cooking at 600 W is what throws many chefs. To heat at a given wattage, check the power rating on the back of the oven (800 W is typical) and then multiply that figure by the power setting (which is given either as a percentage or in numbers from one to 10 representing 10 percent steps). A 1,000-W oven, for example, produces 600 W at a power setting of 60 percent (or “6”). To “fry” parsley brushed with oil, cook it at 600 W for about four minutes. To dry strips of marinated beef into jerky, cook at 400 W for five minutes, flipping the strips once a minute.

If you are up for slightly more math, you can perform a kitchen experiment that Albert Einstein would have loved: prove that light really does zip along at almost 300 million meters per second. Cover a cardboard disk from a frozen pizza with slices of Velveeta and microwave it at low power until several melted spots appear. (You don’t want it rotating, so if your oven has a carousel, prop the cardboard above it.) Measure the distance (in meters) between the centers of the spots. That distance is half the wavelength of the light, so if you double it and multiply by 2.45 billion (the frequency in cycles per second), the result is the velocity of the rays bouncing about in your oven.

Source of Information : Scientific American Magazine

Can’t Touch This Feeling

Written by Science Knowledge on 10:57 AM

Primates can now move and sense the textures of objects using only their thoughts

When real brains operate in the real world, it’s a two-way street. Electrical activity in the brain’s motor cortex speeds down the spinal cord to the part of the body to be moved; tactile sensations from the skin simultaneously zip through the spinal cord and into the brain’s somatosensory cortex. The two actions are virtually inseparable: absent the feel of a floor under your feet, it’s awfully difficult to walk properly, and lacking the tactile sensation of a coffee mug, your brain cannot sense how tightly your fingers should grasp it. Until now, attempts to help paralyzed patients move a prosthetic have addressed only half of our interaction with the world. A new study offers hope of expanding that capacity.
Scientists led by Miguel Nicolelis, professor of neurobiology at Duke University Medical Center, have reported the first-ever demonstration in which a primate brain not only moved a “virtual body” (an avatar hand on a computer screen) but also received electric signals encoding the feel of virtual objects the avatar touched—and did so clearly enough to texturally distinguish the objects. If the technology, detailed in the journal Nature, works in people, it would change the lives of paralyzed patients. (Scientific American is part of Nature Publishing Group.) They would not only be able to walk and move their arms and hands, Nicolelis says, but also to feel the texture of objects they hold or touch and to sense the terrain they tread on.

Other research groups are working on similar advances. At the University of Pittsburgh, neuroscientists led by Andrew Schwartz have begun recruiting patients paralyzed by spinal cord injury into a similar trial that would allow them to “feel” the environment around them thanks to electrodes in the somatosensory cortex that receive information from a robot arm.

Nicolelis hopes to bring his research to fruition by 2014, when he plans to unveil the first “wearable robot” at the opening game of soccer’s World Cup in his home country of Brazil. Think Iron Man, a full-body, exoskeletonlike prosthetic. Its interface will be controlled by neural implants that capture signals from the motor cortex to move legs, hands, fingers and everything else. And it will be studded with sensors that relay tactile information about the outside world to the somatosensory cortex. Buoyed by the advances so far, Nicolelis predicts that the device will be ready in time. “It’s our moon shot,” he says.

Source of Information : Scientific American Magazine


About Me

In its broadest sense, science (from the Latin scientia, meaning "knowledge") refers to any systematic knowledge or practice. In its more usual restricted sense, science refers to a system of acquiring knowledge based on scientific method, as well as to the organized body of knowledge gained through such research.

Fields of science are commonly classified along two major lines: natural sciences, which study natural phenomena (including biological life), and social sciences, which study human behavior and societies. These groupings are empirical sciences, which means the knowledge must be based on observable phenomena and capable of being experimented for its validity by other researchers working under the same conditions.


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