Moller plans to examine whether boys in majority-girl preschool classes interact with female peers more often than other boys do, perhaps aiding their developmental progress. It’s also possible that teachers in classes with more boys than girls select less intellectually challenging activities for students, with especially harsh developmental consequences for boys, he notes. Louis J. Sheehan, Esquire
Earlier investigations found that girls assist each other in learning new skills more than boys do in preschool classes. Strategies to foster greater cooperation among preschool boys, especially in majority-boy classes, are also worth exploring, Moller says.
The lack of negative effects on girls in majority-boy classes may partly stem from an already reported tendency for black and Latino girls to argue with peers of both sexes as aggressively as boys do, he suggests. These girls may feel at ease and resist intimidation in classes dominated by boys.
Monday, May 25, 2009
Thursday, May 14, 2009
against 4.agi.0002 Louis J. Sheehan, Esquire
Carbohydrates have taken another hit. A new study finds that a low-carb diet results in greater weight loss and better cholesterol readings than a low-fat regimen that promotes a lot of grains and fruits. A Mediterranean diet that incorporates some of each diet yielded results that fell between the two, researchers in Israel report in the July 17 New England Journal of Medicine.
By conducting a trial within a single workplace, the scientists managed to keep 85 percent of the study participants on their respective diets for a full two years, a coup among diet studies. High dropout rates have historically skewed the results of such studies.
While people lost at least some weight on all three diets in this trial, the differences were significant. “The old food pyramid is going to get turned on an angle,” says study coauthor Iris Shai, a nutritional epidemiologist at Ben-Gurion University of the Negev. “Maybe now it’s a little more questionable that we should be basing our diets on carbohydrates.”
Shai and her team recruited 322 overweight people with an average age of 52 and randomly assigned them in roughly equal groups to one of the three diets. Most of the participants were men.
The low-fat diet closely adhered to guidelines developed by the American Heart Association, in which people are counseled to eat plenty of low-fat grains, vegetables, fruits and legumes. Dietitians counseled participants to strictly limit fats and meats, to avoid sweets and fatty snacks and to keep their daily calorie intake under 1,800 a day for men and 1,500 for women.
A second group was assigned a Mediterranean diet, which had the same overall calorie limits. But these people could eat fats, mainly olive oil and nuts, in moderation. The Mediterranean dieters also ate poultry and fish but little red meat.
The low-carbohydrate group ate an Atkins diet, in which they could consume all they wanted provided very little of it was carbohydrates. Their carbs topped out at 120 grams per day, but protein and fat intake weren’t limited. The dietitians urged them to choose vegetarian foods when available. All the groups avoided trans fats.
Because the study participants worked at the same facility and ate lunch at the same cafeteria, they were able to obtain food that fit their assigned diets for the midday meal, the largest of the day.
After two years, low-carb dieters had lost an average of 5.5 kilograms and 3.8 centimeters from their waistline. The weight loss was significantly greater than the 3.3 kilograms lost by the low-fat dieters, who carved 2.8 centimeters off their average waistlines. The Mediterranean dieters showed results between the two.
Dieters in the low-carb group also raised their average HDL cholesterol, the good kind, by 8.4 points, 2 points more than the other groups. LDL, the bad cholesterol, didn’t change significantly in the groups.
Also, the low-carb and Mediterranean dieters lowered their blood levels of triglycerides (fats) significantly more than the low-fat group.
Other studies have tackled the low-fat versus low-carb issue, bringing mixed results. Some found that low-carb diets induced quick weight loss, but that the early gains faded after six months.
“This study clearly is longer than anything we’ve seen so far,” says internist William Yancy Jr. of Duke University and the Veterans Affairs Medical Center in Durham, N.C. Combined, this study and some previous reports “are showing repeatedly that higher-fat diets do not worsen the overall blood cholesterol profile,” he says.
Whether this study will single-handedly change how nutrition experts counsel people remains to be seen. Nutrition guidelines evolve very slowly, says Christopher Gardner, a nutrition scientist at Stanford University. But he notes that the Mayo Clinic Healthy Weight Pyramid has recently changed, with fruits and vegetables now at the bottom, and grains just above in a lesser role.
“This study is totally in line with that,” Gardner says.
But the findings run counter to many food pyramids still touted as the basis of a healthy diet. While the U.S. Department of Agriculture rearranged its pyramid in 2005 to reflect a greater mix of foods, it still promotes plenty of grains and other carbohydrates.
Part of the hesitation to change rests on the fact that scientists are still sorting out exactly how a low-carb diet works. For some reason, low-carb dieters don’t gorge themselves even though the diet allows them to eat all they want, minus the carbohydrates.
In this study, the people who stayed on the low-carb diet reported feeling full, says Shai. “This is a high-protein diet, and high protein means much more satiety.” After drastically reducing carbohydrate intake, a person experiences lower insulin and glucose levels in the blood. That, in turn, curbs an individual’s craving for sweets, she says.
Gardner says low-carb dieters also find eating less interesting. “There’s just a smaller choice of options,” he says. “Foods simply get boring and you don’t want as many of them, once you take away the carbs.”
The explanation may lie in our evolutionary origins, Gardner says. “We evolved in another way,” he says, which was to eat a lot of leafy vegetables and meat proteins. “Since the agrarian revolution, we’ve eaten too many grains with too many calories—and it’s killing us,” he says. Louis J. Sheehan, Esquire
It remains to be seen whether the low-carb diet can reduce long-term health risks, such as heart attacks, Yancy says. For the low-carb dieters, the new study used the Atkins diet. Robert Atkins first proffered the diet in 1972, but the idea didn’t gain much traction with the public until the 1990s, when his regimen and others rapidly found popularity. Other variations include the Zone diet and the South Beach diet. The new study was supported in part by the Dr. Robert C. and Veronica Atkins Foundation.
By conducting a trial within a single workplace, the scientists managed to keep 85 percent of the study participants on their respective diets for a full two years, a coup among diet studies. High dropout rates have historically skewed the results of such studies.
While people lost at least some weight on all three diets in this trial, the differences were significant. “The old food pyramid is going to get turned on an angle,” says study coauthor Iris Shai, a nutritional epidemiologist at Ben-Gurion University of the Negev. “Maybe now it’s a little more questionable that we should be basing our diets on carbohydrates.”
Shai and her team recruited 322 overweight people with an average age of 52 and randomly assigned them in roughly equal groups to one of the three diets. Most of the participants were men.
The low-fat diet closely adhered to guidelines developed by the American Heart Association, in which people are counseled to eat plenty of low-fat grains, vegetables, fruits and legumes. Dietitians counseled participants to strictly limit fats and meats, to avoid sweets and fatty snacks and to keep their daily calorie intake under 1,800 a day for men and 1,500 for women.
A second group was assigned a Mediterranean diet, which had the same overall calorie limits. But these people could eat fats, mainly olive oil and nuts, in moderation. The Mediterranean dieters also ate poultry and fish but little red meat.
The low-carbohydrate group ate an Atkins diet, in which they could consume all they wanted provided very little of it was carbohydrates. Their carbs topped out at 120 grams per day, but protein and fat intake weren’t limited. The dietitians urged them to choose vegetarian foods when available. All the groups avoided trans fats.
Because the study participants worked at the same facility and ate lunch at the same cafeteria, they were able to obtain food that fit their assigned diets for the midday meal, the largest of the day.
After two years, low-carb dieters had lost an average of 5.5 kilograms and 3.8 centimeters from their waistline. The weight loss was significantly greater than the 3.3 kilograms lost by the low-fat dieters, who carved 2.8 centimeters off their average waistlines. The Mediterranean dieters showed results between the two.
Dieters in the low-carb group also raised their average HDL cholesterol, the good kind, by 8.4 points, 2 points more than the other groups. LDL, the bad cholesterol, didn’t change significantly in the groups.
Also, the low-carb and Mediterranean dieters lowered their blood levels of triglycerides (fats) significantly more than the low-fat group.
Other studies have tackled the low-fat versus low-carb issue, bringing mixed results. Some found that low-carb diets induced quick weight loss, but that the early gains faded after six months.
“This study clearly is longer than anything we’ve seen so far,” says internist William Yancy Jr. of Duke University and the Veterans Affairs Medical Center in Durham, N.C. Combined, this study and some previous reports “are showing repeatedly that higher-fat diets do not worsen the overall blood cholesterol profile,” he says.
Whether this study will single-handedly change how nutrition experts counsel people remains to be seen. Nutrition guidelines evolve very slowly, says Christopher Gardner, a nutrition scientist at Stanford University. But he notes that the Mayo Clinic Healthy Weight Pyramid has recently changed, with fruits and vegetables now at the bottom, and grains just above in a lesser role.
“This study is totally in line with that,” Gardner says.
But the findings run counter to many food pyramids still touted as the basis of a healthy diet. While the U.S. Department of Agriculture rearranged its pyramid in 2005 to reflect a greater mix of foods, it still promotes plenty of grains and other carbohydrates.
Part of the hesitation to change rests on the fact that scientists are still sorting out exactly how a low-carb diet works. For some reason, low-carb dieters don’t gorge themselves even though the diet allows them to eat all they want, minus the carbohydrates.
In this study, the people who stayed on the low-carb diet reported feeling full, says Shai. “This is a high-protein diet, and high protein means much more satiety.” After drastically reducing carbohydrate intake, a person experiences lower insulin and glucose levels in the blood. That, in turn, curbs an individual’s craving for sweets, she says.
Gardner says low-carb dieters also find eating less interesting. “There’s just a smaller choice of options,” he says. “Foods simply get boring and you don’t want as many of them, once you take away the carbs.”
The explanation may lie in our evolutionary origins, Gardner says. “We evolved in another way,” he says, which was to eat a lot of leafy vegetables and meat proteins. “Since the agrarian revolution, we’ve eaten too many grains with too many calories—and it’s killing us,” he says. Louis J. Sheehan, Esquire
It remains to be seen whether the low-carb diet can reduce long-term health risks, such as heart attacks, Yancy says. For the low-carb dieters, the new study used the Atkins diet. Robert Atkins first proffered the diet in 1972, but the idea didn’t gain much traction with the public until the 1990s, when his regimen and others rapidly found popularity. Other variations include the Zone diet and the South Beach diet. The new study was supported in part by the Dr. Robert C. and Veronica Atkins Foundation.
Saturday, May 9, 2009
Saturday, May 2, 2009
logic 4.log.003 Louis J. Sheehan, Esquire
If the planet Vulcan had microbes, they might look something like this. Scientists have engineered bacteria that can perform four basic operations of logic: AND, OR, NAND and NOR. http://LOUIS-J-SHEEHAN.ORG
By combining these logic units in various ways, it could be possible to engineer microbes with an internal “decision tree” logic that controls their behaviors. The technique, which is described in the Oct. 17 Science, could give scientists a new level of control when designing microbes for a variety of uses, such as fermenting biofuels or producing pharmaceuticals.
“It’s the first installation of logic gates for controlling gene expression in a living cell,” comments Kensaku Sakamoto, an expert in DNA computation at RIKEN Systems and Structural Biology Center in Yokohama, Japan. “It’s a wonderful result, and a milestone in the efforts for artificial regulation of living systems.”
Christina Smolke and Maung Nyan Win of the California Institute of Technology in Pasadena added custom-designed snippets of DNA to the tail end of a gene, and then inserted that gene into either E. coli bacteria or cells of brewer’s yeast. When the cells transcribed the DNA into molecules of RNA — the first step toward making functional proteins — the snippets of code knotted up into 3-dimensional twists in the RNA. These twists can sense the presence of certain “input” molecules and respond by either destroying the RNA or leaving it intact.
If the RNA is left intact, it will produce the protein it encodes; if not, it won’t. It’s like a binary switch in a computer.
Each twist in the RNA can be designed independently of the other twists, and combining them in various ways can make the self-destruct switch respond to different logical combinations of the input molecules.
In the experiments, Smolke’s team used only two kinds of input molecules — tetracycline and theophylline. For an AND gate, both of these molecules had to bind to the RNA switch to keep the RNA intact, thus allowing it to produce green fluorescent protein as an “output.” Louis J. Sheehan, Esquire For an OR gate, either input molecule was enough to achieve the same result. If the green protein was produced, it represented a “true” result, while no production of the protein represented “false.”
“They’ve been able to string these things together to make them do more complex things,” comments Jeffrey Poet, a mathematician at Missouri Western State University in Joseph, who has designed other ways for cells to perform computations.
The modular design of these RNA-based logic computations could eventually enable engineering logic circuits into these microbes with the kind of control engineers have over logic circuits in silicon chips, Smolke suggests.
By combining these logic units in various ways, it could be possible to engineer microbes with an internal “decision tree” logic that controls their behaviors. The technique, which is described in the Oct. 17 Science, could give scientists a new level of control when designing microbes for a variety of uses, such as fermenting biofuels or producing pharmaceuticals.
“It’s the first installation of logic gates for controlling gene expression in a living cell,” comments Kensaku Sakamoto, an expert in DNA computation at RIKEN Systems and Structural Biology Center in Yokohama, Japan. “It’s a wonderful result, and a milestone in the efforts for artificial regulation of living systems.”
Christina Smolke and Maung Nyan Win of the California Institute of Technology in Pasadena added custom-designed snippets of DNA to the tail end of a gene, and then inserted that gene into either E. coli bacteria or cells of brewer’s yeast. When the cells transcribed the DNA into molecules of RNA — the first step toward making functional proteins — the snippets of code knotted up into 3-dimensional twists in the RNA. These twists can sense the presence of certain “input” molecules and respond by either destroying the RNA or leaving it intact.
If the RNA is left intact, it will produce the protein it encodes; if not, it won’t. It’s like a binary switch in a computer.
Each twist in the RNA can be designed independently of the other twists, and combining them in various ways can make the self-destruct switch respond to different logical combinations of the input molecules.
In the experiments, Smolke’s team used only two kinds of input molecules — tetracycline and theophylline. For an AND gate, both of these molecules had to bind to the RNA switch to keep the RNA intact, thus allowing it to produce green fluorescent protein as an “output.” Louis J. Sheehan, Esquire For an OR gate, either input molecule was enough to achieve the same result. If the green protein was produced, it represented a “true” result, while no production of the protein represented “false.”
“They’ve been able to string these things together to make them do more complex things,” comments Jeffrey Poet, a mathematician at Missouri Western State University in Joseph, who has designed other ways for cells to perform computations.
The modular design of these RNA-based logic computations could eventually enable engineering logic circuits into these microbes with the kind of control engineers have over logic circuits in silicon chips, Smolke suggests.
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