Rapid Neutrino Cooling in the Neutron Star MXB 1659-29.

We show that the neutron star in the transient system MXB 1659-29 has a core neutrino luminosity that substantially exceeds that of the modified Urca reactions (i.e., n+n→n+p+e^{-}+ν[over ¯]_{e} and inverse) and is consistent with the direct Urca (n→p+e^{-}+ν[over ¯]_{e} and inverse) reaction occurring in a small fraction of the core. Observations of the thermal relaxation of the neutron star crust following 2.5 yr of accretion allow us to measure the energy deposited into the core during accretion, which is then reradiated as neutrinos, and infer the core temperature. For a nucleonic core, this requires that the nucleons are unpaired and that the proton fraction exceeds a critical value to allow the direct Urca reaction to proceed. The neutron star in MXB 1659-29 is the first with a firmly detected thermal component in its x-ray spectrum that needs a fast neutrino-cooling process. Measurements of the temperature variation of the neutron star core during quiescence would place an upper limit on the core specific heat and serve as a check on the fraction of the neutron star core in which nucleons are unpaired.

Incidence of venous thromboembolic events among nursing home residents.

Chronic care facility stay has been shown to be an independent risk factor for venous thromboembolism. Review of the literature, however, reveals a paucity of data addressing the issue of venous thromboembolism in nursing home residents. The purpose of this study was to determine the incidence of venous thromboembolic events among nursing home residents. A retrospective cohort study was derived from data compiled in the State of Kansas Minimum Data Set (MDS) for nursing home residents from July 1, 1997 to July 1, 1998. A total of 18,661 residents (median age, 85 years, 74% female, 95% white) satisfied the study criteria. The outcome measures of the primary endpoint-development of a venous thromboembolic event (VTE)-were obtained from the MDS quarterly health assessments and the Medicare ICD-9 codes. We determined the incidence of VTE among nursing home residents as 1.30 events per 100 person-years of observation.

Urban-rural patterns of increasing antidepressant use among nursing facility residents.

OBJECTIVE: To characterize changing patterns of antidepressant use in nursing facilities across the urban-rural continuum during the mid-1990s. DESIGN: Retrospective analysis of antidepressant drug codes and demographic/clinical data from the Minimum Data Set (MDS) 1994 to 1997. SETTING: Kansas nursing facilities. PARTICIPANTS: Facility residents aged 65 and older. MEASUREMENTS: We examined (1) admission use and (2) after-admission use for newer and older antidepressants for each year separately, using a 4-stratum system to classify nursing facility location by county, from urban to most rural. Incidence rate ratios were determined for antidepressant use in each stratum using the urban strata as the reference. RESULTS: Remarkable increases in use of newer antidepressants were seen over time in all strata, but use was highest in the urban area. Modest urban-rural gradient effects attenuated over time and were not consistently seen across analyses and years. Tricyclic antidepressant (TCA) use remained largely unchanged over time and at much lower rates than newer agents. However, TCA use was also modestly higher in urban areas. Differences were clearer for use after admission, in contrast with admission use patterns. CONCLUSIONS: Newer antidepressants were rapidly adopted across the urban-rural continuum from 1994 to 1997. Marked increases in both admission and after-admission use of newer antidepressants were seen. Both newer and older antidepressants were used at modestly higher rates in urban areas. Further work is needed to elucidate the patient, prescriber, and facility factors that explain these prescribing patterns.

Urban-rural differences in amitriptyline use among nursing facility residents.

OBJECTIVE: To characterize patterns of amitriptyline use across the urban-rural continuum. DESIGN: Retrospective analysis of antidepressant drug codes and demographic and clinical data from the Minimum Data Set (MDS), 1994 to 1997. SETTING: Kansas nursing facilities. PARTICIPANTS: Facility residents aged 65 and older. MEASURES: A four-strata system was used to classify nursing facility location by county, from urban to frontier. We examined admission use and after-admission use of amitriptyline across strata for each year separately. Unadjusted and adjusted odds ratios were determined for each stratum, using the urban stratum as the point of reference. RESULTS: Admission use of amitriptyline occurred in 2.3 to 4% of all admissions, and although such use was highest in the most rural stratum, no clear urban-rural gradient was found. In contrast, amitriptyline use 30 days or more after admission demonstrated modest urban-rural gradients in unadjusted and adjusted analyses. In 1997, when adjusted for demographic factors, odds ratios for amitriptyline use were 2.10 (1.54-2.87), 1.68 (1.33-2.13), and 1.49 (1.17-1.90) for the Frontier, Rural, and Densely Settled Rural categories as compared with the Urban reference group. CONCLUSIONS: After admission to Kansas nursing facilities, rural practice patterns for amitriptyline use are less favorable than those in urban areas, and an urban-rural gradient is identified. Further work is needed to identify explanatory patient, facility, and prescriber factors.