Re−Ni2B2C superconducting borocarbides: “In situ” growth of thin films, transport and point contact spectroscopy

High quality c-axis oriented films of the intriguing intermetallic superconducting compound YNi₂B₂C have been obtained “in situ” by magnetron sputtering on MgO substrates held at about 800°C. The films showed maximum T_c=15.3 K, †T_c≈0.1 K, room temperature resistivity ρ≈50μΩ·cm, critical current J_c≈10⁵ A/cm² and B_c2≈6 T. Superconducting films were also obtained on Al₂O₃ and LaAlO₃ single-crystal substrates. From the ρ(T) dependence a value of the Debye temperature Θ _D =330±20 K can be deduced. At low temperatures the resistivity follows a quadratic power law possibly indicative of a high value of the electron-phonon interaction parameter λ. In order to clarify the role of λ in these compounds, point contact spectroscopy measurements have been performed on YNi₂B₂C and HoNi₂B₂C bulk samples prepared by inductive melting using a Low Temperature Scanning Tunneling Microscope (LTSTM). In the point contact regime clear evidence of a superconducting gap have been found in both compounds, corresponding to a moderate strong coupling behaviour (2†/KT_c≈3.8).     

Service system integration, access to services, and housing outcomes in a program for homeless persons with severe mental illness

OBJECTIVES: This study evaluated the hypothesis that greater integration and coordination between agencies within service systems is associated with greater accessibility of services and improved client housing outcomes. METHODS: As part of the Access to Community Care and Effective Services and Supports program, data were obtained on baseline client characteristics, service use, and 3-month and 12-month outcomes from 1832 clients seen at 18 sites during the first year of program operation. Data on interorganizational relationships were obtained from structured interviews with key informants from relevant organizations in each community (n = 32-82 at each site). RESULTS: Complete follow-up data were obtained from 1340 clients (73%). After control for baseline characteristics, service system integration was associated with superior housing outcomes at 12 months, and this relationship was mediated through greater access to housing agencies. CONCLUSIONS: Service system integration is related to improved access to housing services and better housing outcomes among homeless people with mental illness.     

Ovarian vein syndrome

SETTING: A voluntary community health worker programme, in the Western Cape, South Africa, utilizing volunteers to administer directly observed therapy to tuberculosis (TB) patients. OBJECTIVE: This study describes the perceptions of health team members regarding the voluntary community health worker project. DESIGN: A qualitative, participatory research study utilizing focus groups. RESULTS: TB was perceived by the health team to be a stigmatized disease causing some patients to be reluctant to be associated with the TB control programme. Despite the project's dedicated approach to case-holding, volunteers expressed the need to develop skills in providing more comprehensive care. The volunteers appear to administer a more personalized service to TB patients and can bridge the gap between TB patients and the health agency. CONCLUSION: Sustained evaluation and support seem to be a vital tool in integrating a volunteer project into a health team approach. Its effectiveness appears to depend to a large degree on the people involved.     

Upper abdominal surgery: does a lung function test exist to predict early severe postoperative respiratory complications?

We evaluated the capacity to predict severe respiratory complications (SRCs) following upper abdominal surgery (UAS) by using the results of a respiratory questionnaire and preoperative pulmonary function tests. Lung volumes, flows and transfer factor of the lung for carbon monoxide (TL,CO,sb) were assessed in 361 consecutive adult patients (248 males and 113 females). SRCs were diagnosed 24 h after UAS by clinical examination and chest radiography. Univariate and stepwise multiple logistic regression analyses were performed to estimate the odds ratio (OR) and 95% confidence interval (95% CI) of each single input variable, and to determine which indices best predicted outcome. These patients had a 1% mortality rate and 14% incidence of SRCs, with a male:female ratio of 0.86. The best predictors for SRCs by multiple analysis were: preoperative current hypersecretion of mucus (OR=133; p<0.0001); an increase in residual volume (RV) (OR=3.11; p=0.01); and, to a lesser extent, low percentage of predicted values both of forced expiratory volume in one second (FEV1 % pred) and TL,CO,sb. The algorithm thus obtained (logit theta) was extremely sensitive (84%), specific (99%), and accurate (95%) for preoperative prediction of SRCs. We have found that preoperative current hypersecretion of mucus and pulmonary hyperinflation, and to a lesser extent percentage predicted values both of forced expiratory volume in one second and transfer factor of the lung for carbon monoxide, have a significant predictive capacity for severe respiratory complications following upper abdominal surgery.     

The pharmaco-erection test

Intracavernous administration of vasoactive drugs induces an erection in absence of erotic stimuli; we can use this property in the study of impotent patients, inducing the appearance on an erection to examine it in all its phases (FIC Test). In case of the appearance of a good erection, the test should rule out the presence of a penile arterial disease or of a corpora-veno-occlusive deficiency. When the administration of the drug does not cause complete tumescence, it is very probable that the erectile dysfunction is caused by arterial vascular alterations or by organic disorders of veno-occlusion mechanism, but we cannot exclude for a certainty a psychogenic dysfunction. In fact an excessive noradrenergic autonomic control, as during stress condition, may limit FIC Test response. Therefore we hope that more efficacious molecules will be available in a near future. Nevertheless, we consider the opportunity of enclosing tests in the diagnostic algorithm of impotent patients to reveal an excessive adrenergic tone, such as, for example, psychological tests, study of cavernous potential, or intracavernous catecholamine dosage.     

Flow of a third grade fluid through a porous flat channel

The steady, laminar flow of a third grade fluid through a porous flat channel is considered, when the rate of injection of the fluid at one boundary is equal to the rate of suction at the other boundary. The flow is governed by a non-linear boundary value problem (BVP) in which the order of the differential equation is three, but only two boundary conditions are available. Two numerical schemes are developed to obtain the appropriate solution of the BVP. In the first scheme the dilemma is resolved by assuming that the solution is analytical in the neighborhood of K=0, where K is the non-dimensional viscoelastic fluid parameter. This scheme is practical to use only up to certain values of T, the third grade fluid parameter. The second scheme allows arbitrary values of T, but is restricted to small values of K and R, the cross-flow Reynolds number.A perturbation solution valid for small values of T is also derived. Finally two approximate solutions, based on Collatz’ iterative scheme, but with different starting trial solutions are obtained. A comparison is made of the results computed by using various methods and appropriate conclusions are drawn.     

如何选择电流互感变压器

长期以来，电流互感变压器作为仪器设备中的一种标准器件一直用来测量精密电流。即使在恶劣的环境和高温条件下，这种器件也非常精确，使用方便可靠。