Postponing the inevitable. We all do it, from postponing a visit to the dentist to putting off that mammogram appointment. People in all walks of life often feel that what they don't know won't hurt them. But sometimes it does. Results from a new study by MED and SPH Associate Professor Jeffrey Samet indicate that HIV-infected patients seek medical care on average more than eight years after acquiring the infection. This behavior, says Samet, prevents patients from receiving the full benefit of new advances in HIV therapy. It also places more people at risk for infection.

Between 1994 and 1996 the researchers interviewed patients coming for HIV treatment for the first time and examined CD4 blood counts. The blood count is an indicator of how compromised the immune system is, and provides a basis for estimating the time between getting the infection and seeking treatment. The interview questions measured how long individuals had been aware of their risk of HIV infection, and ascertained information on lifestyle characteristics associated with their awareness of their risk of infection.

The researchers found that the majority of patients were at an advanced stage of immunosuppression, signifying that infection took place years before. Patients with heterosexual HIV risk behaviors were most often unaware of their risk of HIV, but even patients who were aware of their risk delayed an average of two and a half years before getting tested.

"The fact that more than one-third of patients were unaware of their HIV risk before testing suggests that some public health HIV messages are not being communicated," says Samet. "Our data suggest the need for aggressive public health campaigns that enhance HIV risk awareness and personalize the problem."

A new state of liquid matter. Using complex computational simulations, Center for Polymer Studies researchers Giancarlo Franzese, CAS research associate, Anna Skibinsky (GRS'02), Sergey Buldyrev, CAS research associate, and H. Eugene Stanley, CAS professor and the center's director, and Gianpietro Malescio at the University of Messina, Italy, have concluded that the "stuff" of reality exists in states beyond the usual three -- solid, liquid, and gas.

The researchers demonstrated the existence of two distinct liquid states -- high-density and low-density -- for a variety of materials, including liquid metals, by identifying precise combinations of temperature and pressure where the materials switch suddenly from one state to another. In both liquid states the molecules remain the same, just the way water, whether liquid, ice, or steam, is always composed of two hydrogen atoms and an oxygen atom. The difference is in how the molecules pack together. In high-density liquids, molecules are closer together and more tightly organized than they are in low-density liquids. If the combinations of pressure and temperature where the transitions occur are plotted, they describe a line ending in a critical point. Here the difference between the two phases disappears: the molecules are organized at a distance that lies between the high-density and low-density states. Along the line of phase transitions, the two liquid states exist simultaneously, just as water and steam exist simultaneously at the boiling point.

The researchers predict that this theoretical discovery will lead to confirming experiments and perhaps to the discovery of several additional states of matter.

The work appears in the February 8 issue of the journal Nature.

This research, presented by Skibinsky, who played a central role, and other outstanding research by graduate students will be featured at Science Day 2001, on Tuesday, March 27, in the George Sherman Union.