Magnetism and magnetic isomers in free chromium clusters.

We have used the Stern-Gerlach deflection technique to study magnetism in chromium clusters of 20-133 atoms at temperatures between 60 and 100 K. We observe that these clusters have large magnetic moments and respond superparamagnetically to applied magnetic fields. Using superparamagnetic theory, we have determined the moment per atom for each cluster size and find that it often far exceeds the moment per atom present anywhere in the bulk antiferromagnetic lattice. Remarkably, our cluster beam contains two magnetically distinguishable forms of each cluster size with > or =34 atoms. We attribute this observation to structural isomers.

Duplicate publication and 'paper inflation' in the Fractals literature.

The similarity of documents in a large database of published Fractals articles was examined for redundancy. Three different text matching techniques were used on published Abstracts to identify redundancy candidates, and predictions were verified by reading full text versions of the redundancy candidate articles. A small fraction of the total articles in the database was judged to be redundant. This was viewed as a lower limit, because it excluded cases where the concepts remained the same, but the text was altered substantially. Far more pervasive than redundant publications were publications that did not violate the letter of redundancy but rather violated the spirit of redundancy. There appeared to be widespread publication maximization strategies. Studies that resulted in one comprehensive paper decades ago now result in multiple papers that focus on one major problem, but are differentiated by parameter ranges, or other stratifying variables. This 'paper inflation' is due in large part to the increasing use of metrics (publications, patents, citations, etc) to evaluate research performance, and the researchers' motivation to maximize the metrics.

Severe intimate partner violence and alcohol use among female trauma patients.

BACKGROUND: The lifetime prevalence of intimate partner violence (IPV) among women in the United States is reported to be between 18 and 50%. One-third of female homicide victims are killed by an intimate partner and alcohol is often involved. Despite these figures, 77% of women have never been screened for IPV. Substance abuse in male partners is known to place women at risk. We examined the role of female alcohol use on rates of severe IPV. Our hypotheses were: (1) the prevalence of IPV among women seen in trauma centers is greater than that found in national surveys; (2) alcohol problems among abused women and their partners are greater than those among non-abused women; (3) females and their partners alcohol problems are each independently associated with IPV; and (4) female trauma center patients support domestic violence screening. METHODS: An in-person survey was administered to 95 consecutive adult female trauma patients admitted to a Level I Trauma Center. The survey included questions about past-year and lifetime severe IPV, female and male partner alcohol use, and willingness to participate in IPV screening and referral. The multivariate associations of female and partner alcohol use with past-year severe IPV were assessed with logistic regression. RESULTS: Nearly one-half (46.3%) of women reported a lifetime history of severe IPV, with 26% experiencing severe IPV in the past year. Past-year IPV was identified in 59.1% of women screening positive for drinking problems, but in only 12.7% of those screening negative for drinking problems (p = 0.001). Similarly, past-year IPV prevalence was 55.2% when the partner was a problem drinker versus 8.3% when he was not (p = 0.001). Multivariate analysis showed that female problem drinking (odds ratio [OR] = 5.8) and partner problem drinking (OR=8.9) were independent predictors of past-year severe IPV. The majority of women (90.5%) felt that it was appropriate for health care professionals to screen for IPV; 90% of women with a history of IPV thought screening was important and 71% wished a previous healthcare provider had asked them about it. CONCLUSIONS: Female trauma patients demonstrate a higher prevalence of severe IPV than the general population. IPV rates appear to be related to both female and partner alcohol misuse. Female trauma patients endorsed IPV screening and thus should be screened for alcohol use and IPV in a way that minimizes future violence risk. Further research is needed to elucidate whether intervention for alcohol misuse has an impact on rates of IPV in this population.

Photodesorption of alkali anions from alkali-halide cluster anions.

Using photoelectron spectroscopy, we have observed alkali anion photodesorption from alkali-halide cluster anions that contain two weakly bound electrons. In the alkali iodides, we have found this type of desorption in almost every (MI)(n)M- cluster we have studied (M=Na, K, Cs; n<9), although it depends on the probe laser frequency and cluster temperature. Using pump-probe techniques, we have shown that the process occurs on a picosecond time scale by way of an electronic excitation of the cluster's spin-paired electrons.

Time-resolved dynamics of thermal isomerization in cesium-halide cluster anions.

We have performed time-resolved studies of the dynamics of thermal isomerization occurring in certain cesium-halide cluster anions. Using a pump-probe technique, we have observed the repopulation of a photodepleted isomer within an ensemble as a function of time by monitoring the photoelectron spectrum. The rates of isomerization increase and the isomer lifetimes decrease as functions of temperature. The clusters undergo a gradual phase transition from solid-like to liquid-like states with liquid-like behavior obtained at approximately 500 K, much lower than the bulk melting temperatures of approximately 900 K.

Generation of continuous-wave radiation near 243 nm by sum-frequency mixing in an external ring cavity.

We have generated up to 1 mW of single-mode cw ultraviolet radiation between 243 and 247 nm by mixing the outputs of an ultraviolet argon-ion laser at 363.8 nm and a red LD700 dye laser in ammonium dihydrogen phosphate. The dye-laser intensity within the crystal is enhanced by using an actively locked passive ring cavity. Wavelengths near 243.1 nm are of particular interest for the high-resolution two-photon spectroscopy of atomic hydrogen.

Generation of continuous-wave ultraviolet radiation by sum-frequency mixing in an external ring cavity.

We have generated several milliwatts of single-frequency cw UV radiation near 265 nm by mixing the outputs of a rhodamine 6G ring dye laser and a 488-nm argon-ion laser in a crystal of ammonium dihydrogen phosphate. The dye-laser intensity inside the crystal was enhanced by a frequency-locked passive ring cavity, yielding at least a tenfold improvement in UV power over earlier mixing schemes. An envisioned extension to wavelengths near 243 nm is of particular interest for high-resolution two-photon spectroscopy of atomic hydrogen.