http://www.sharpbrains.com/blog/2006/11/06/brain-coach-answers-how-can-i-improve-my-short-term-memory-is-there-an-daily-exercise-i-can-do-to-improve-it/
Is there a daily exercise I can do to improve it?
A: The most important component of memory is attention. By choosing to attend to something and focus on it, you create a personal interaction with it, which gives it personal meaning, making it easier to remember.Elaboration and repetition are the most common ways of creating that personal interaction. Elaboration involves creating a rich context for the experience by adding together visual, auditory, and other information about the fact. By weaving a web of information around that fact, you create multiple access points to that piece of information. On the other hand, repetition drills in the same pathway over and over until it is a well-worn path that you can easily find.
One common technique used by students, is actually, not that helpful. Mnemonic techniques of using the first letter of each word in a series won't help you remember the actual words. It will help you remember the order of words you already know. The phrase My Very Energetic Mother Just Screamed Utter Nonsense can help you remember the order the planets in our solar system, but it won't help you recall the individual planet names: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
These techniques do help you improve your memory on a behavioral level, but not on a fundamental brain structure level. The main reason it gets harder for you to learn and remember new things as you age is that your brain's processing speed slows down as you get older. It becomes harder to do more than one thing at the same time, so it’s easier to get confused. Your brain may also become less flexible, so it’s harder to change learning strategies in mid-stream. All these things mean it becomes harder to focus. So far, there’s nothing you can do to change your brain’s processing speed, but there are techniques you can use to increase your learning performance, even if your processing speed has slowed.
FocusAlertness, focus, concentration, motivation, and heightened awareness are largely a matter of attitude. Focus takes effort. In fact, most memory complaints have nothing to do with the actual ability of the brain to remember things. They come from a failure to focus properly on the task at hand.
If you want to learn or remember something, concentrate on just that one thing. Tune out everything else. The harder the task, the more important it is to tune out distractions. (If someone tells you they can do their homework better with the TV or radio on, don't believe it. Any speech or speech-like sounds automatically use up part of your brain’s attention capacity, whether you are aware of it or not.) In other words, it can be hard to do more than one thing at once, and it naturally gets harder as you get older. The solution is to make more of an effort not to let yourself get distracted until you’ve finished what you have to do.
Strategy:When you learn something new, take breaks so that the facts won’t interfere with one another as you study them. If you’ve ever been to a movie double feature, you know that you’ll have a hard time remembering the plot and details of the first movie immediately after seeing the second. Interference also works the other way. Sometimes when your friend gets a new telephone number, the old one will still be so familiar to you that it’s hard to remember the new one.
EngageYour brain remembers things by their meaning. If you spend a little effort extra up front to create meaning, you’ll need less effort later to recall it. When you read or hear a word you don't already know — for example, "phocine" — your brain has to work harder. First, you have to remember how to spell it long enough to look it up in a dictionary. There, you’ll see it means “seal-like” and it’s pronounced “fo-sine.” Now picture a seal in your mind and repeat the word aloud. Even say “Fo! Fo! Fo!” aloud like a seal barking. The sound of the word, its spelling, the image of a seal, and the barking all work together to form memory links. The more links the better to help you trigger the word later on, when you want to use it to describe, say, a sunbather in a black one-piece.
Strategy:Say you’re on vacation in Maui, staying at a beachfront hotel in room #386. How do you remember that? Method number one: Pause for a minute to take a mental snapshot of your room door viewed from an outside vantage point. Then, when you return to that same vantage point, you’ll know which door is yours. Method number two: Stop and think for a minute. You’re on the third floor, which is the top floor of the hotel, so the number 3 is easy. Now for the 8 and the 6. The expression “to eighty-six” comes to mind — as in to get rid of, do away with, or throw out. As in what your boss will do to you if you decide to spend an extra week in Maui. Done.
Links:
Cognitive Neuroscience and ADD/ADHD Today
Computerized Working Memory Training
Strategies for Regulating Emotional Memory
10 Memory Tricks for Elementary Students
Memorization Strategies in Cognitive Rehabilitation
Saturday, November 17, 2007
Tuesday, September 4, 2007
From YottaInfo.com
Poor Dental Hygiene May Account for Poor Health
Bright white teeth and fresh breath does not necessarily mean you have a healthy mouth! General health is directly related to gum health. Gum disease has been linked to several medical conditions such as stroke, diabetes, heart attack and worsening lung disease. Healthy gums can reduce a person's biological age by up to 6.4 years. Why? Because studies show that the presence of periodontal diseases, most common in people with tooth loss, actually affects longevity. The best of these studies, done at Emory University in conjunction with the Centers for Disease Control, indicates that people with gingivitis and periodontal disease have a mortality rate that is 23% to 46% higher than those who don't. Keeping your gums clean and healthy may help reduce the risk of many illnesses, including heart disease.
Gum Disease
Gum disease or periodontal disease, a chronic inflammation and infection of the gums and surrounding tissue, is the major cause of about 70 percent of adult tooth loss, affecting three out of four persons at some point in their life. Red swollen and bleeding gums characterize gum disease in the initial stages and progresses to infections, chronic inflammation and bone loss in later stages. Eventually bacteria are allowed to flow freely through your gums and into your blood stream that activates and stresses the immune system.
Heart Attack
Research shows that people with gum disease are 25% more likely to have a heart attack. Bacteria originating from the gums to the veins and arteries cause plaque build up and arterial inflammation that can provoke jeopardous clotting. A 12-year study conducted by Harvard University researchers and 41,000 healthy men free of cardiovascular disease showed that those with periodontal disease had more clot related strokes.
Diabetes
Periodontal disease severely affects the control of blood sugars. The spread of bacteria through out the body through the blood stream stresses and confuses the body when trying to adjust sugars to the invasion. Antibiotic treatment has help diabetics control blood sugars while treating the infections caused by gum disease.
Lung Infections
Breathing in oral bacteria caused by gum disease can cause lung infections. Bacteria that grow in the oral cavities can be breathed into the lungs to cause respiratory disease such as pneumonia.
About the Author
Yvonne Takhtalian, C.N.H.P, H.I. spent the past 10 years developing and improving Vita-Myr Natural Products helping thousands like you heal gum disease and gingivitis. She just released a new line of 100% Natural Vita-Myr Soaps to compliment her Vita-Myr Mouthwash & Toothpaste. Find out more about effective natural relief of gum disease at http://www.vitamyr.com/ or email questions/comments to Yvonne at mailto:vitamyr@mindspring.com Copyright © 2004 Vita-Myr® International Inc All rights reserved. Natural Products For Healthy Living ®
Tuesday, August 28, 2007
El verdadero idiota
Se cuenta que en una ciudad del interior un grupo de personas se divertía con un idiota de la aldea, un pobre infeliz, de poca inteligencia, que vivía de pequeñas changas y limosnas. Diariamente ellos llamaban al idiota al bar donde se reunían y le ofrecían escoger entre dos monedas: una grande de 400reales y otra pequeña de 2000 reales. Él siempre escogía la grande y menos valiosa, lo que era motivo de risas para todos.
Cierto día, alguien que observaba al grupo le llamó aparte y le preguntó si todavía no había percibido que la moneda grande valía menos. Lo sé, respondió, no soy tan bobo. Ella vale cinco veces menos, pero el día que escoja la otra, el jueguito acaba y no voy a ganar más mi moneda.
Esta historia podría concluir aquí, como un simple chiste, pero se pueden sacar varias conclusiones:
La primera: Quien parece idiota, no siempre lo es.
La segunda: ¿Cuáles eran los verdaderos idiotas de la historia?
La tercera: Una ambición desmedida puede acabar cortando tu fuente de ingresos.
Pero la conclusión más interesante es: Podemos estar bien, aún cuando los otros no tengan una buena opinión sobre nosotros mismos.
Por lo tanto, lo que importa no es lo que piensan de nosotros, pero sí lo que realmente somos.
El mayor placer de un hombre inteligente es aparentar ser idiota delante de un idiota que aparenta ser inteligente.
Cierto día, alguien que observaba al grupo le llamó aparte y le preguntó si todavía no había percibido que la moneda grande valía menos. Lo sé, respondió, no soy tan bobo. Ella vale cinco veces menos, pero el día que escoja la otra, el jueguito acaba y no voy a ganar más mi moneda.
Esta historia podría concluir aquí, como un simple chiste, pero se pueden sacar varias conclusiones:
La primera: Quien parece idiota, no siempre lo es.
La segunda: ¿Cuáles eran los verdaderos idiotas de la historia?
La tercera: Una ambición desmedida puede acabar cortando tu fuente de ingresos.
Pero la conclusión más interesante es: Podemos estar bien, aún cuando los otros no tengan una buena opinión sobre nosotros mismos.
Por lo tanto, lo que importa no es lo que piensan de nosotros, pero sí lo que realmente somos.
El mayor placer de un hombre inteligente es aparentar ser idiota delante de un idiota que aparenta ser inteligente.
Sunday, July 22, 2007
The End of Cheap Food - Interesante artículo.
Este comentario me lo envió una amiga:
I recently had a meeting with a friend who was formerly the president of the New York Mercantile Exchange. In addition to his extensive commodities trading experience, his family has been in the food processing business for many decades. He proposed over lunch that the world was running out of food - that for the first time in decades there was no surplus food in the markets and that his family business was searching the world for surplus commodities (the basis of their business) where in the past they had
always operated off of U.S. excesses. His professional opinion was that prices of food would increase substantially (3 to 5 times) in the coming years, and then he proceeded to explain the underlying relationships that would drive that upward swing, a confluence that similarly came together in the early 70s.
It was only a matter of days after that conversation that I received the following confirming post from the Global Business Network, of which I am a member.
The End of Cheap Food
By Gwynne Dyer
The era of cheap food is over. The price of corn (maize) has doubled in a year, and wheat futures are at their highest in a decade. The food price index in India has risen 11 percent in one year, and in Mexico in January there were riots after the price of corn flour (used in making the staple food of the poor, tortillas) went up fourfold. Even in the developed countries food prices are going up, and they are not going to come down again.
Cheap food lasted for only fifty years. Before the Second World War most families in the developed countries spent a third or more of their income on food (as the poor majority in developing countries still do). But after the war a series of radical changes, from mechanization to the Green Revolution, raised agricultural productivity hugely and caused a long, steep fall in the real price of food. For the global middle class, it was the Good Old Days, with food taking only a tenth of their income.
It will probably be back up to a quarter within a decade, and it may go much higher than that, because we are entering a period when three separate factors are converging to drive food prices up. The first is simply demand.
Not only is the global population continuing to grow (about an extra Turkey or Vietnam every year), but as Asian economies race ahead more and more people in those populous countries are starting to eat significant amounts of meat.
Early this month, in its annual assessment of farming trends, the United Nations predicted that by 2016, less than ten years from now, people in the developing countries will be eating 30 percent more beef, 50 percent more pig meat and 25 percent more poultry. The animals will need a great deal of grain, and meeting that demand will require shifting huge amounts of grain-growing land from human to animal consumption -- so the price of grain and of meat will both go up.
The global poor don't care about the price of meat, because they can't afford it even now -- but if the price of grain goes up, some of them will starve. And maybe they won't have to wait until 2016, because the mania for "bio-fuels" is shifting huge amounts of land out of food production.
One-sixth of all the grain grown in the United States this year will be "industrial corn" destined to be converted into ethanol and burned in cars, and Europe, Brazil and China are all heading in the same direction.
The attraction of bio-fuels for politicians is obvious: they can claim that they are doing something useful to combat emissions and global warming (though the claims are deeply suspect), without actually demanding any sacrifices from business or the voters. The amount of US farmland devoted to bio-fuels grew by 48 percent in the last year alone, and hardly any new land was brought under the plough to replace the lost food production. In other big bio-fuel producers like China and Brazil it's the same straight switch from food to fuel. In fact, the food market and the energy market are becoming closely linked, which is very bad news for the poor.
As oil prices rise (and the rapid economic growth in Asia guarantees that they will), they pull up the price of bio-fuels as well, and it gets even more attractive for farmers to switch from food to fuel. Nor will politics save the day. As economist Lester Brown of the Earth Policy Institute told the US Congress last month: "The stage is now set for direct competition for grain between the 800 million people who own
automobiles, and the world's two billion poorest people." Guess who wins.
Soaring Asian demand and bio-fuels mean expensive food now and in the near future, but then it gets worse. Global warming hits crop yields, but only recently has anybody quantified how hard. The answer, published in "Environmental Research Letters" in March by Christopher Field of the Carnegie Institution in Stanford, California and David Lobell of Lawrence Livermore National Laboratory, is quite simple: for every 0.5C (0.9F) hotter, crop yields fall between three and five percent. So two degrees C hotter (3.6F), the lower end of the range of predicted temperature rise in this century, means a twelve to twenty percent fall in global food production.
This is science, of course, so that answer could be wrong -- but it could be wrong by being too conservative. Last year in New Delhi, I interviewed the director of a think tank who had just completed a contract to estimate the impact on Indian food production of a rise of just two degrees C in global
temperature. The answer, at least for India, was 25 percent. That would mean mass starvation, for if India were in that situation, every other major food-producing country would be too, and there would be no imports available at any price.
In the early stages of this process, higher food prices will help millions of farmers who have been scraping along on very poor returns for their effort because political power lies in the cities, but later
it gets uglier. The price of food relative to average income is heading for levels that have not been seen since the early 19th century, and it will not come down again in our lifetimes.
____________________________
Gwynne Dyer, Ph.D., is a London-based independent journalist and GBN Network member whose articles are published in 45 countries.
I recently had a meeting with a friend who was formerly the president of the New York Mercantile Exchange. In addition to his extensive commodities trading experience, his family has been in the food processing business for many decades. He proposed over lunch that the world was running out of food - that for the first time in decades there was no surplus food in the markets and that his family business was searching the world for surplus commodities (the basis of their business) where in the past they had
always operated off of U.S. excesses. His professional opinion was that prices of food would increase substantially (3 to 5 times) in the coming years, and then he proceeded to explain the underlying relationships that would drive that upward swing, a confluence that similarly came together in the early 70s.
It was only a matter of days after that conversation that I received the following confirming post from the Global Business Network, of which I am a member.
The End of Cheap Food
By Gwynne Dyer
The era of cheap food is over. The price of corn (maize) has doubled in a year, and wheat futures are at their highest in a decade. The food price index in India has risen 11 percent in one year, and in Mexico in January there were riots after the price of corn flour (used in making the staple food of the poor, tortillas) went up fourfold. Even in the developed countries food prices are going up, and they are not going to come down again.
Cheap food lasted for only fifty years. Before the Second World War most families in the developed countries spent a third or more of their income on food (as the poor majority in developing countries still do). But after the war a series of radical changes, from mechanization to the Green Revolution, raised agricultural productivity hugely and caused a long, steep fall in the real price of food. For the global middle class, it was the Good Old Days, with food taking only a tenth of their income.
It will probably be back up to a quarter within a decade, and it may go much higher than that, because we are entering a period when three separate factors are converging to drive food prices up. The first is simply demand.
Not only is the global population continuing to grow (about an extra Turkey or Vietnam every year), but as Asian economies race ahead more and more people in those populous countries are starting to eat significant amounts of meat.
Early this month, in its annual assessment of farming trends, the United Nations predicted that by 2016, less than ten years from now, people in the developing countries will be eating 30 percent more beef, 50 percent more pig meat and 25 percent more poultry. The animals will need a great deal of grain, and meeting that demand will require shifting huge amounts of grain-growing land from human to animal consumption -- so the price of grain and of meat will both go up.
The global poor don't care about the price of meat, because they can't afford it even now -- but if the price of grain goes up, some of them will starve. And maybe they won't have to wait until 2016, because the mania for "bio-fuels" is shifting huge amounts of land out of food production.
One-sixth of all the grain grown in the United States this year will be "industrial corn" destined to be converted into ethanol and burned in cars, and Europe, Brazil and China are all heading in the same direction.
The attraction of bio-fuels for politicians is obvious: they can claim that they are doing something useful to combat emissions and global warming (though the claims are deeply suspect), without actually demanding any sacrifices from business or the voters. The amount of US farmland devoted to bio-fuels grew by 48 percent in the last year alone, and hardly any new land was brought under the plough to replace the lost food production. In other big bio-fuel producers like China and Brazil it's the same straight switch from food to fuel. In fact, the food market and the energy market are becoming closely linked, which is very bad news for the poor.
As oil prices rise (and the rapid economic growth in Asia guarantees that they will), they pull up the price of bio-fuels as well, and it gets even more attractive for farmers to switch from food to fuel. Nor will politics save the day. As economist Lester Brown of the Earth Policy Institute told the US Congress last month: "The stage is now set for direct competition for grain between the 800 million people who own
automobiles, and the world's two billion poorest people." Guess who wins.
Soaring Asian demand and bio-fuels mean expensive food now and in the near future, but then it gets worse. Global warming hits crop yields, but only recently has anybody quantified how hard. The answer, published in "Environmental Research Letters" in March by Christopher Field of the Carnegie Institution in Stanford, California and David Lobell of Lawrence Livermore National Laboratory, is quite simple: for every 0.5C (0.9F) hotter, crop yields fall between three and five percent. So two degrees C hotter (3.6F), the lower end of the range of predicted temperature rise in this century, means a twelve to twenty percent fall in global food production.
This is science, of course, so that answer could be wrong -- but it could be wrong by being too conservative. Last year in New Delhi, I interviewed the director of a think tank who had just completed a contract to estimate the impact on Indian food production of a rise of just two degrees C in global
temperature. The answer, at least for India, was 25 percent. That would mean mass starvation, for if India were in that situation, every other major food-producing country would be too, and there would be no imports available at any price.
In the early stages of this process, higher food prices will help millions of farmers who have been scraping along on very poor returns for their effort because political power lies in the cities, but later
it gets uglier. The price of food relative to average income is heading for levels that have not been seen since the early 19th century, and it will not come down again in our lifetimes.
____________________________
Gwynne Dyer, Ph.D., is a London-based independent journalist and GBN Network member whose articles are published in 45 countries.
Saturday, June 2, 2007
Pensioners who pump iron defy ageing
LONDON- Gym training can rejuvenate the muscles of pensioners in a way that appears to reverse ageing, a study has shown.
Astonished researchers found that muscle tissue actually seemed to become younger.
Some 25 over-65s, with an average age of 70, took part in the study and trained at a gym.
Not only did they acquire new strength, but the molecular machinery powering their muscles became as active as that seen in people of 20 or 30.
In the first study of its kind, the Canadian scientists measured gene activity in tissue removed from the pensioners' thighs and compared it with samples from a group of 20 to 35-year-olds.
Dr Simon Melov, who co-led the research at McMaster University Medical Centre in Hamilton, Ontario, said: "We were very surprised by the results of the study. We expected to see gene expressions that stayed fairly steady in the older adults.
"The fact that their 'genetic fingerprints' so dramatically reversed course gives credence to the value of exercise, not only as a means of improving health, but of reversing the ageing process itself."
Young and old volunteers had similar diets and levels of daily exercise, and none took medicines or had diseases that might have affected the study results.
The older participants were put through six months of resistance training using standard gym equipment. Twice-weekly sessions were held, each an hour in length, which involved 30 contractions of each muscle group.
Measurements of muscle strength showed that before training, the pensioners were on average 59 per cent weaker than the young adults. Afterwards, they were only 38 per cent weaker - an improvement of almost 50 per cent.
But the most remarkable change was hidden in the mitochondria, the rod-like 'power plants' that sit within every cell and generate energy.
Numerous studies have indicated that mitochondrial dysfunction is involved in the muscle loss and functional impairment seen in older people.
Measuring gene "expression", or activity, in the mitochondria allowed the scientists to shine a light on one of the key elements of ageing.
They found that exercise reversed this genetic fingerprint back to levels similar to those seen in the young volunteers.
Four months after the study was completed, most of the pensioners were no longer going to a gym, but carrying on simple lifting exercises or working with elastic bands at home.
"They were still as strong, they still had the same muscle mass," said Dr Mark Tarnopolsky, another member of the McMaster team.
"This shows that it's never too late to start exercising and that you don't have to spend your life pumping iron in a gym to reap benefits."
The findings were reported in the on-line journal PLoS One.
The scientists are designing further studies to find out whether resistance training has any genetic impact on organs and other types of tissue.
They also want to investigate the effect of endurance exercise, such as running or cycling, on mitochondrial function and the ageing process.
Looking at gene expressions could provide the starting point for developing drug therapies that affect ageing.
Dr Melov said: "The vast majority of ageing studies are done in worms, fruit flies and mice; this study was done in humans.
"It's particularly rewarding to be able to scientifically validate something practical that people can do now to improve their health and the quality of their lives, as well as knowing that they are doing something which is actually reversing aspects of the ageing process."
PA cjh
Astonished researchers found that muscle tissue actually seemed to become younger.
Some 25 over-65s, with an average age of 70, took part in the study and trained at a gym.
Not only did they acquire new strength, but the molecular machinery powering their muscles became as active as that seen in people of 20 or 30.
In the first study of its kind, the Canadian scientists measured gene activity in tissue removed from the pensioners' thighs and compared it with samples from a group of 20 to 35-year-olds.
Dr Simon Melov, who co-led the research at McMaster University Medical Centre in Hamilton, Ontario, said: "We were very surprised by the results of the study. We expected to see gene expressions that stayed fairly steady in the older adults.
"The fact that their 'genetic fingerprints' so dramatically reversed course gives credence to the value of exercise, not only as a means of improving health, but of reversing the ageing process itself."
Young and old volunteers had similar diets and levels of daily exercise, and none took medicines or had diseases that might have affected the study results.
The older participants were put through six months of resistance training using standard gym equipment. Twice-weekly sessions were held, each an hour in length, which involved 30 contractions of each muscle group.
Measurements of muscle strength showed that before training, the pensioners were on average 59 per cent weaker than the young adults. Afterwards, they were only 38 per cent weaker - an improvement of almost 50 per cent.
But the most remarkable change was hidden in the mitochondria, the rod-like 'power plants' that sit within every cell and generate energy.
Numerous studies have indicated that mitochondrial dysfunction is involved in the muscle loss and functional impairment seen in older people.
Measuring gene "expression", or activity, in the mitochondria allowed the scientists to shine a light on one of the key elements of ageing.
They found that exercise reversed this genetic fingerprint back to levels similar to those seen in the young volunteers.
Four months after the study was completed, most of the pensioners were no longer going to a gym, but carrying on simple lifting exercises or working with elastic bands at home.
"They were still as strong, they still had the same muscle mass," said Dr Mark Tarnopolsky, another member of the McMaster team.
"This shows that it's never too late to start exercising and that you don't have to spend your life pumping iron in a gym to reap benefits."
The findings were reported in the on-line journal PLoS One.
The scientists are designing further studies to find out whether resistance training has any genetic impact on organs and other types of tissue.
They also want to investigate the effect of endurance exercise, such as running or cycling, on mitochondrial function and the ageing process.
Looking at gene expressions could provide the starting point for developing drug therapies that affect ageing.
Dr Melov said: "The vast majority of ageing studies are done in worms, fruit flies and mice; this study was done in humans.
"It's particularly rewarding to be able to scientifically validate something practical that people can do now to improve their health and the quality of their lives, as well as knowing that they are doing something which is actually reversing aspects of the ageing process."
PA cjh
Tuesday, May 29, 2007
Discovery News - Health Food
Pink Grapefruit Juice Most Nutritious
Jennifer Viegas,
Discovery News
May 29, 2007 — Pink grapefruit juice provides more nutrients per calorie than any other 100 percent fruit juice, according to a new study that analyzed several juices commonly found in major U.S. markets.
The pucker-inducing pink drink just edged out orange juice, which also ranked high, but soundly beat white grapefruit, pineapple, prune, grape and apple juices, which rated in that order, with non-citrus juices like apple falling behind high vitamin C content varieties.
Author Gail Rampersaud, a researcher at the Institute of Food and Agricultural Sciences at the University of Florida, told Discovery News that pink grapefruit juice "is an excellent source of vitamin C," providing an entire day’s recommended amount in a single 8-ounce glass.
"It also provides potassium, folate, thiamin and magnesium, as well as certain carotenoids that can be converted into vitamin A in the body," she added. "Pigmented grapefruit juices, such as pink or ruby, also contain lycopene, a carotenoid that gives pigmented grapefruit its rich color."
Carotenoids are color-giving substances found in orange and yellow fruits and vegetables. They are also present in dark green leafy veggies. Prior studies suggest these compounds may help to prevent cancer and other diseases.
For the recent research, Rampersaud focused only on common 100 percent fruit juices. This left out tomato juice, which is primarily marketed as a vegetable juice, and cranberry juice, which most often is sold as cranberry juice "cocktail," with less than 30 percent actual cranberry juice or within a blend of other juices.
Pomegranate, blueberry, cherry and other rich juices also usually come in blends, so they were eliminated for the same reason.
She used six different methods to calculate each juice’s nutrient density, which is defined as either nutrients provided per calorie or the ratio of the amount of a nutrient in foods to the energy provided by these same foods.
One method, for example, involved calculating the average recommended daily value amount for certain known nutrients based on 2,000 kilocalories, or units used to express the energy-producing potential of food. Nutrients included proteins, fats, sugars, numerous vitamins and minerals and other components.
Findings are published in the current issue of the Journal of Food Science.Rampersaud explained that citrus juices ranked high "because they generally have higher amounts of a wider variety of nutrients compared to the other juices included in the analysis, coupled with the fact that the citrus juices are lower in calories."
In recent years, the U.S. Department of Health and Human Services has urged consumers to focus on nutrient dense foods and beverages to avoid excess calorie intake.
Adam Drewnowski, director of the Center for Public Health Nutrition at the University of Washington, has conducted several related studies.
He told Discovery News that Rampersaud did "a very impressive job."
Drewnowski added, however, that current nutrient density methodologies do not allow for inclusion of phytochemicals and antioxidants, which are substances that, like carotenoids, may also end health benefits.
Earlier studies have found that very dark juices like pomegranate and blueberry, even in blends, provide high amounts of these compounds.
A food to wash down with all of that juice might be spinach, which Drwenowski said is "the most nutrient dense food," along with broccoli and red peppers, which also provide substantial nutritional bang per calorie buck.
Wednesday, May 23, 2007
Discovery News - Biology
Female Sharks Reproduce Without Dad
Jennifer Viegas,
Discovery News
May 23, 2007 — Virgin births are possible in female sharks, according to a new study that determined a captive female bonnethead shark reproduced without having been near a male in three years.
Since other captive females — including a white spotted bamboo shark — have anecdotally accomplished the same feat, researchers conclude it is likely all shark species possess the ability.
The recent determination, made possible through DNA analysis, actually applies to the birth of a bonnethead shark (of the hammerhead family) that occurred six years ago at the Henry Doorly Zoo in Nebraska.
"It was a big surprise for us," zoo director Lee Simmons told Discovery News.
Simmons added, "We brought in three female bonnetheads on December 15, 1998, and on December 14, 2001, bang! One of them gave birth to an 8-inch-long offspring."
The pup unfortunately died the same day from internal injuries likely caused by a stingray in the same exhibit that munched the wiry infant and then spit it out. Puzzled by the birth, Simmons and his team put the offspring on ice and handed it over to the Guy Harvey Research Institute at Nova Southeastern University.
At this point Simmons said he considered all possibilities, including a delayed pregnancy, which is possible in some insects that can store sperm and then give birth much later.
Mahmood Shivji, director of the institute, and his team collected tissue samples from all of the zoo’s female bonnetheads. DNA analysis, which took several years, identified one female as the mother.
Research on the perished pup found that it had no paternal DNA. Additionally, it possessed half of its mother’s genetic diversity. Combined, the data indicates the mother gave birth through a non-sexual mode of reproduction known as automatic parthenogenesis.
Shivji explained to Discovery News that this process involves the female creating an egg that contains fifty percent of the mother’s genes. It is induced to behave as though it has been fertilized by a tiny, genetically similar cell called a sister polar body.
The resulting offspring therefore is doubly genetically disadvantaged.
"It had no father to provide genetic diversity, and it even lacks its mother’s full genetic makeup," Shivji said.
He speculates that such births can only occur when females do not have access to males, such as in a captive setting, or in the wild when overfishing depletes shark populations.
"We now are concerned, because if conditions prompt asexual reproduction in the wild, the species could be at an evolutionary disadvantage," he said.
While the new research, published in today’s Royal Society Biology Letters, represents a rare, documented case of an asexual birth in a shark, it's already known that certain birds, reptiles and amphibians also possess the ability.
Shivji said it is significant that sharks can now be added to the list, since they are the world’s oldest living vertebrates, a group of backboned animals that also includes humans.
Since humans and mammals lack the ability, he suspects it evolved early on in the vertebrate lineage, but was lost in some groups when they diverged from their common ancestor with sharks about 450 million years ago.
Jennifer Viegas,
Discovery News
May 23, 2007 — Virgin births are possible in female sharks, according to a new study that determined a captive female bonnethead shark reproduced without having been near a male in three years.
Since other captive females — including a white spotted bamboo shark — have anecdotally accomplished the same feat, researchers conclude it is likely all shark species possess the ability.
The recent determination, made possible through DNA analysis, actually applies to the birth of a bonnethead shark (of the hammerhead family) that occurred six years ago at the Henry Doorly Zoo in Nebraska.
"It was a big surprise for us," zoo director Lee Simmons told Discovery News.
Simmons added, "We brought in three female bonnetheads on December 15, 1998, and on December 14, 2001, bang! One of them gave birth to an 8-inch-long offspring."
The pup unfortunately died the same day from internal injuries likely caused by a stingray in the same exhibit that munched the wiry infant and then spit it out. Puzzled by the birth, Simmons and his team put the offspring on ice and handed it over to the Guy Harvey Research Institute at Nova Southeastern University.
At this point Simmons said he considered all possibilities, including a delayed pregnancy, which is possible in some insects that can store sperm and then give birth much later.
Mahmood Shivji, director of the institute, and his team collected tissue samples from all of the zoo’s female bonnetheads. DNA analysis, which took several years, identified one female as the mother.
Research on the perished pup found that it had no paternal DNA. Additionally, it possessed half of its mother’s genetic diversity. Combined, the data indicates the mother gave birth through a non-sexual mode of reproduction known as automatic parthenogenesis.
Shivji explained to Discovery News that this process involves the female creating an egg that contains fifty percent of the mother’s genes. It is induced to behave as though it has been fertilized by a tiny, genetically similar cell called a sister polar body.
The resulting offspring therefore is doubly genetically disadvantaged.
"It had no father to provide genetic diversity, and it even lacks its mother’s full genetic makeup," Shivji said.
He speculates that such births can only occur when females do not have access to males, such as in a captive setting, or in the wild when overfishing depletes shark populations.
"We now are concerned, because if conditions prompt asexual reproduction in the wild, the species could be at an evolutionary disadvantage," he said.
While the new research, published in today’s Royal Society Biology Letters, represents a rare, documented case of an asexual birth in a shark, it's already known that certain birds, reptiles and amphibians also possess the ability.
Shivji said it is significant that sharks can now be added to the list, since they are the world’s oldest living vertebrates, a group of backboned animals that also includes humans.
Since humans and mammals lack the ability, he suspects it evolved early on in the vertebrate lineage, but was lost in some groups when they diverged from their common ancestor with sharks about 450 million years ago.
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