A bit farther down in the biomedical ranking, another hot field deals with thrombo-poietin, a protein that regulates production of blood platelets. In clinical trials, this hormone and its derivatives have shown promise in boosting platelet production in cancer patients who have undergone stem-cell transplants, and other patients dealing with bone-marrow failure. Still another hot biomedical field centers on prostate-specific antigen (PSA) expression in non-prostate tissue, such as the female breast. The core papers for this front examine PSA expression as a clinical indicator in the diagnosis and tracking of breast cancer and other malignancies.

   Of the hot fields in the physical sciences, many involve aspects of microfabrication, including quantum structures known as dots and islands that are currently under investigation for use in optoelectronics and other applications. In the field of polymeric self-assembled monolayers, the core authors include George M. Whitesides of Harvard University, who was featured in these pages last summer as a particularly prolific author of high-impact papers in chemistry/materials science (see Science Watch, 8[4]:1-2, July/August 1997). Research on thin films and intermetallic compounds also made the hot list.

   Three of the hot physical-sciences fields concern superconductivity, a topic that virtually ruled the Physics Top Ten lists as recently as two years ago but which has been relatively scarce of late. The top-ranked of the three superconductivity fields listed here concerns loss of the current in superconducting materials. Always a topic of interest, the question of AC losses is being addressed with greater vigor now that prospects for superconductor applications are growing more realistic.

   With 40 core papers, the investigation of borocarbide superconductors constitutes the largest cluster in this study. As superconductivity expert John R. Clem, Iowa State University, Ames, tells Science Watch, researchers initially believed that these materials might have the potential to rival the high transition temperatures seen in cuprate superconductors. "Although this dream was not fulfilled," notes Clem, "it was discovered that borocarbides exhibit a very interesting interplay, or competition, between magnetism and superconductivity, and thus borocarbide superconductivity became a research area with its own merits." The third superconductivity specialty area looks at the fundamental question concerning the symmetry of the pairing state in high-temperature superconductors. Evidence is mounting in favor of d-wave, as opposed to s-wave, symmetry. However, as Clem observes, this particular area will likely take years to explore fully.

   Represented by two specialty areas, the observation and manipulation of single molecules constitutes another theme in the physical-sciences table. One field concerns the detection of single molecules by means of fluorescence microscopy. Researchers in the other field-among them Steven Chu of Stanford University, co-winner of the 1997 Nobel Prize in physics-employ the technique of focused lasers known as "optical tweezers" to zero in on individual polymer chains. By tethering and then stretching strands of DNA and other polymers, researchers can observe the molecular dynamics of unwinding and relaxation.

   Among the five fastest-moving, "superhot" fields, highlights include research on speech recognition systems that may someday do away with the keyboard and mouse. The ongoing hunt for genes implicated in schizophrenia (two have been identified thus far) also registers strongly. Another field to watch is evidence-based medicine. In this new approach to medical practice, physicians-instead of relying on long-held habits or personal preferences in regard to treatment-consult the latest data from clinical trials to identify the best course of action for each patient.