Stories of modern science... from UPI

, April 11 (UPI) -- MILITARY DEVELOPS INDESTRUCTIBLE SANDWICH

A new sandwich being developed by the U.S. military is tough enough to be dropped out of an airplane and is designed to last for up to three years, according to a New Scientist report. The new "pocket" sandwich will stay fresh for three years at the temperature of a warm summer day, and for six months at around 100 degrees Fahrenheit. The sandwich could supplement the military's standard fare, called "Meal Ready-to-Eat" (MRE). The sandwiches are more easily eaten on the go than the MREs, which are stored in and must be prepared from a series of pouches. The researchers at the U.S. Army Soldier Systems Center in Natick, Mass., added substances called humectants to pepperoni and chicken to prevent water from leaking out of them and making the bread soggy. The pepperoni and barbecue-chicken sandwiches were rated as "acceptable" by soldiers, and pocket pizzas, cream-filled bagels, breakfast burritos, and peanut-butter sandwiches are next on the menu.

INBREEDING DETRIMENT DEMONSTRATED GENETICALLY

It has long been believed that inbreeding is unhealthy for offspring, and geneticists have now proved it, at least in mustard weed. In work described in this week's edition of the journal Nature, researchers compared the amino acid substitutions in the mustard weed to similar substitutions in fruit flies, and found that the substitutions were more often detrimental in the weed. "We attribute this difference to the Arabidopsis mating system of partial self-fertilization," said Michael D. Purugganan, associate professor in the department of genetics at North Carolina State. "(That) corroborates a prediction in genetics theory that species with a high frequency of inbreeding will be less efficient in eliminating deleterious mutations ... This is also one reason why it is important to increase population sizes of endangered species -- small populations may lead to build-up of bad mutations, and make it more difficult to save these species."

MUTATIONS IN MEN DRIVE EVOLUTION

A new study shows that men carry 5.25 times the number of genetic mutations as women, meaning that evolution is male-driven, according to a report in this week's edition of the journal Nature. The mutations appear to be caused mainly by random errors that occur during cell divisions rather than by environmental factors. "Mutation is the ultimate source of variation," said Wen-Hsiung Li, a professor in the department of ecology and evolution at the University of Chicago. Male germ cells accumulate mutations as they go through cell divisions throughout a man's lifetime, whereas a woman's egg cells only go through 24 cell divisions, most before she is born. So is a man's biological clock ticking? Should he worry about accumulated mutations ruining his sperm? "The mutation rate is very low, so the increase in mutations in an individual male is not appreciable," Li said, "even if you were to double or triple the rate."

ASTRONOMERS FIND STAR MADE OF QUARKS

Astronomers using the Chandra X-ray observatory have discovered a novel type of star that appears to be made entirely of quarks, according to a New Scientist report. The odd finding came as they were observing the remnants of supernovae. The star is very small, measuring just 11 kilometers across. "This is an astonishing discovery with fundamental significance," said Norman Glendenning, a neutron star theorist at Lawrence Berkeley National Laboratory. Jeremy Drake and colleagues at the Harvard-Smithsonian Center for Astrophysics used the Hubble Space Telescope to measure the star's size, and Chandra's X-ray observations showed it is 100 times hotter than our sun. Others think that the observation may be merely a "hot spot" on the surface of a larger neutron star. "Very few people will be convinced that this is an iron-clad case," said Mike Turner, an astrophysicist at the University of Chicago.

(EDITOR: For more information on sandwich, call 44-207 331 2751; about inbreeding, call 919-515-1761; about men, call 773-702-6241)