منابع مشابه
Why lymph nodes grow
At the initiation of an immune response, lymph nodes can double in size in a day and can be ten times their original size in five to seven days. Webster and colleagues report on page 1903 that dendritic cells, quite distinct from their function in antigen presentation, stimulate endothelial cell proliferation and vascular growth in the growing lymph node. Peripheral challenge (such as immunizat...
متن کاملWhy Do Some People Drink Too Much?
17 A lcohol is available to any adult, and illegally to many minors, in the United States. Although most people abstain or drink safely, a sizable minority of the population abuses alcohol. Understanding why alcohol leads to trouble for many, but not most, people exposed to it is the goal of re s e a rc h on the cause (i.e., etiology) of alcohol abuse and alcoholism. It is already clear that so...
متن کاملWhy do people get fat: is adipose tissue guilty?
The prevalence of obesity within the UK is increasing. Comparable surveys conducted in 1980 and 1986/7 (Knight, 1983; Gregory el al. 1990) showed that, even in the more health-conscious 1980s, the proportion of men and women with body mass indices (BMI) greater than 30 rose from 6 to 8% (men) and from 8 to 12% (women). Interest in the question ‘Why do people get fat?’ is, therefore, as great as...
متن کاملWhy are some people left-handed? An evolutionary perspective.
Since prehistoric times, left-handed individuals have been ubiquitous in human populations, exhibiting geographical frequency variations. Evolutionary explanations have been proposed for the persistence of the handedness polymorphism. Left-handedness could be favoured by negative frequency-dependent selection. Data have suggested that left-handedness, as the rare hand preference, could represen...
متن کاملWhy do some people look older than they should?
BACKGROUND As a component of studies on biological age, the age of subjects from their appearance (perceived age) was estimated. OBJECTIVE To determine the factors associated with looking older. METHODS Cross sectional study of London civil servants (318 men, 129 women) in the Department of the Environment study. Perceived age was recorded by an observer and the difference between this age ...
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ژورنال
عنوان ژورنال: Scientific American
سال: 1886
ISSN: 0036-8733
DOI: 10.1038/scientificamerican10161886-8995supp