We can listen to a car radio and drive while keeping an eye on changing traffic conditions -- separate complex tasks completed without much trouble. But if two people are talking to us at the same time, our perceptual frequencies get jammed.
Researchers have found for the first time that tarantulas can produce silk from their feet as well as their spinnerets, a discovery with profound implications for why spiders began to spin silk in the first place.
Ancient rocks from the bottom of the Pacific Ocean suggest dramatic climate changes during the dinosaur-dominated Mesozoic Era, a time once thought to have been monotonously hot and humid.
Emanuel Hanski, a microbiologist at Hebrew University in Jerusalem, and colleagues have found that the success of group A Streptococcus is due in part to a protein that blocks the immune system's distress calls. The findings, published in the October 4, 2006, issue of the EMBO Journal, could lead to new strategies for treating necrotizing fasciitis and halting its rapid destruction of tissue. The paper was published in advance online.
The bacterium, group A Streptococcus, wreaks destruction on muscle and skin tissue in the form of necrotizing fasciitis, which kills roughly 30 percent of its victims and leaves the rest disfigured. Antibiotics and surgical interventions, the known treatments, often fail. Necrotizing fasciitis is a serious but rare infection of the skin and the tissues beneath it.
Laws that require minors to notify or get the consent of one or both parents before having an abortion reduce risky sexual behavior among teens, according to a Florida State University law professor in Tallahassee, Fla.
Jonathan Klick, the Jeffrey A. Stoops Professor of Law, and Thomas Stratmann, professor of economics at George Mason University, came to that conclusion after they looked at the rates of gonorrhea among teenage girls as a measure of risky sex in connection to the parental notification or consent laws that were in effect at the time.
The researchers found that teen gonorrhea rates dropped by an average of 20 percent for Hispanic girls and 12 percent for white girls in states where parental notification laws were in effect. The results were not statistically significant for black girls. The study will be published in an upcoming edition of The Journal of Law Economics and Organization.
"Incentives matter," Klick said. "They matter even in activities as primal as sex, and they matter even among teenagers, who are conventionally thought to be short-sighted. If the expected costs of risky sex are raised, teens will substitute less risky activities such as protected sex or abstinence."
In this case, the incentive for teens is to avoid having to tell their parents about a pregnancy by substituting less risky sex activities. In doing so, the researchers say, the rates of gonorrhea among girls under the age of 20 went down.
"This suggests that Hispanic and white teenage girls are forward looking in their sex decisions, and they systematically view informing their parents and obtaining parental consent as additional costs in obtaining an abortion, inducing them to engage in less risky sex when parental involvement laws are adopted," Klick said. "Unfortunately, the data do not allow us to differentiate between the possibility that teens engage in less sex or they simply have the same amount of sex but are more fastidious in their condom use."
The researchers ruled out the possibility that teens simply substitute risky sexual behaviors for which pregnancy is not a concern, such as oral or anal intercourse, because these activities still could transmit gonorrhea. The use of birth control pills also would not protect against the sexually transmitted disease.
The researchers used data from the Centers for Disease Control to determine the rates of gonorrhea for women by age and race for the years 1981 through 1998. Gonorrhea rates for teenage girls were compared to those of women 20 and older whose behavior would not be affected by the notification and consent laws. Using the rate of gonorrhea among older women as a control, the researchers were able to ensure that the decline in incidence among the teens was not simply reflective of an overall decline of the disease in the state.
Forty-four states, including Florida, have adopted laws requiring minors to obtain consent or notify one or both parents prior to an abortion, but the laws have been blocked by the courts or otherwise not yet enforced in nine of those states, according to the Center for Reproductive Rights.