A new high-precision optical technique to measure magnetostrictionof a thin magnetic film deposited on a substrate

The drive in data storage technology towards utilizing magnetic films with lower magnetostriction (to reduce the magnetoelastic energy term) and reduced thickness has resulted in the requirement for more sensitive, reliable, and easy-to-use tools to monitor magnetostriction. A measurement tool based on an in-plane rotating and saturating magnetic field and laser-beam-deflection technique, which is able to meet these requirements, is described. The tool developed offers high accuracy, large dynamic range, long-term stability, simple sample insertion, and a fast, easy measurement procedure. With this tool, the measurement of small magnetostriction coefficients of thin soft-magnetic films can become a simple, fast, and reliable procedure, thus helping the development of magnetic thin-film production processes and routine composition control     

Thermo-Optic Switching Effect Based on Fluid-Filled Photonic Crystal Fiber

We report a thermo-optic switching effect with a high extinction ratio of 30 dB by means of filling a fluid into air holes of a solid-core photonic crystal fiber (PCF). Such an effect can perform a turn on–off operation of the transmitted light via a small temperature adjustment of $pm$10 $^{circ}hbox{C}$. The switching function attributes to the absorption of the filled fluid in combination with the interaction between the core mode and the excited “fluid rod” modes, resulting from the thermo-optic effect of the filled fluid.      

Predictors of smoking cessation among elderly smokers treated for nicotine dependence

OBJECTIVE: To examine outcomes and predictors of smoking cessation among elderly patients treated for nicotine dependence. DESIGN: Retrospective analysis of patients aged 65-82 who received a nicotine dependence consultation at the Mayo Medical Center between 1 April 1988 and 30 May 1992. Patients were contacted by telephone by a trained interviewer six months after the consultation and were sent a follow-up survey in August 1993. SETTING: Mayo Medical Center, Rochester, Minnesota, United States. SUBJECTS: A total of 613 patients (310 men, 303 women) with a mean age of 69.0 (SD 3.5) years were seen during the study period. MAIN OUTCOME MEASURES: Point prevalence self-reported smoking status. Patients were considered abstinent if they self- reported not smoking (not even a puff) during the seven days before contact. RESULTS: At six-month follow up, 24.8% of the 613 patients reported abstinence from smoking. On multivariate analysis, smoking abstinence was more likely if patients were hospitalised at the time of the consultation, married to a non-smoking spouse, very motivated to stop smoking, and reported their longest time of previous abstinence to be less than a day or more than a month. The response rate to the mailed follow-up survey was 69.9% (429 of 613). The mean duration of follow up was 40.0 +/- 13.2 months following the consultation. Of the 429 patients, 103 (24.0%) reported abstinence from smoking and 326 (76.0%) were smoking at six-month follow up. Patients who reported abstinence at six months had a higher cessation rate at the last follow up (76.0%) compared with patients who were smoking at six-month follow up (33.0%, P < 0.001). For patients who were not smoking at six months, no factors were found to significantly predict abstinence at last follow up. For patients who were smoking at six months, factors associated with smoking cessation at last follow up were: more than a year as the longest time off cigarettes before the consultation; counsellor rating of less severe nicotine dependence; and older age at first regular smoking. CONCLUSIONS: Several predictors of smoking cessation were identified in this study which may be useful for tailoring smoking interventions for the elderly.


     

Can anti-HLA antibody analyses postcardiac transplantation predict acute allograft rejection and survival?

The immunosuppressive agent FK 506 is widely used in liver transplant patients. Neurotoxicity is a major complication of its use. We report progressive and irreversible neurologic complications occurring in a 39-year-old woman who underwent liver transplantation and was treated with FK 506. Neuropathologic examination revealed multiple vasculitic lesions. The possibility of an FK 506-mediated toxic effect on the cerebral vessels is suggested.     

A neuronal ryanodine receptor mediates light-induced phase delays of the circadian clock

Circadian clocks are complex biochemical systems that cycle with a period of approximately 24 hours. They integrate temporal information regarding phasing of the solar cycle, and adjust their phase so as to synchronize an organism's internal state to the local environmental day and night. Nocturnal light is the dominant regulator of this entrainment. In mammals, information about nocturnal light is transmitted by glutamate released from retinal projections to the circadian clock in the suprachiasmatic nucleus of the hypothalamus. Clock resetting requires the activation of ionotropic glutamate receptors, which mediate Ca2+ influx. The response induced by such activation depends on the clock's temporal state: during early night it delays the clock phase, whereas in late night the clock phase is advanced. To investigate this differential response, we sought signalling elements that contribute solely to phase delay. We analysed intracellular calcium-channel ryanodine receptors, which mediate coupled Ca2+ signalling. Depletion of intracellular Ca2+ stores during early night blocked the effects of glutamate. Activators of ryanodine receptors induced phase resetting only in early night; inhibitors selectively blocked delays induced by light and glutamate. These findings implicate the release of intracellular Ca2+ through ryanodine receptors in the light-induced phase delay of the circadian clock restricted to the early night.     

Analysis of diffusional broadening of vesicular packets of catecholamines released from biological cells during exocytosis.

Secretion of catecholamines is observed as a series of current spikes when measured at the surface of a bovine adrenal medullary cell in culture with a carbon-fiber microelectrode operated in the amperometric mode. Prior work has shown that these spikes are due to detection of concentrated packets of catecholamines which are released from individual vesicles after their fusion with the cell membrane, a process known as exocytosis. The shape of the individual current spikes, detected with a 5-microns spacing between the hemispherical cell and the electrode, has been compared to the shape generated by a theoretical model. The model consists of an instantaneous point source of material on a surface which subsequently diffuses to a disk that consumes the emitted material. The pertinent diffusion conditions have been evaluated with finite difference and random walk digital simulations. The two methods give identical results when the point source is located on a plane. The more realistic simulation geometry, emission from a hemispherical surface, was evaluated with the random walk method. The simulations allow a set of criteria to be established to evaluate diffusion-controlled broadening of spike shape. The broad range of spike widths observed experimentally and their individual shapes measured with 5-microns cell-electrode spacing are consistent with diffusion from point sources randomly distributed across a hemispherical surface. The data can be described with the diffusion coefficient for catecholamines in free solution. The model enables evaluation of signal-to-noise losses and correction for diffusional losses which are dependent on electrode radius.(ABSTRACT TRUNCATED AT 250 WORDS)     

The predictive value of electrodiagnostic studies in carpal tunnel syndrome

In recent years, electrodiagnostic studies have become an expected component in the work up and evaluation of carpal tunnel syndrome. We conducted a retrospective review of 460 carpal tunnel decompressions to determine whether the accuracy of diagnosis and the prediction of therapeutic outcome could be related to the positivity and severity of findings on preoperative electrical studies. The 349 patients (460 hands) were divided into two groups: group 1 consisted of hands with the clinical diagnosis of carpal tunnel syndrome but with normal electrodiagnostic studies (n = 62); in group 2 the hands had a clinical diagnosis of carpal tunnel syndrome with confirmatory electrodiagnostic studies (n = 398). The number and distribution of signs and symptoms of carpal tunnel syndrome were not statistically different between these two groups. There was not a statistically significant difference in the success rate of surgery or the incidence of complications. The similarities between these two groups suggests that the distinction between them (the positivity of electrodiagnostic studies) is an artificial one and that the clinical diagnosis of carpal tunnel syndrome is sufficient to predict the presence of the disease, as well as outcome of surgery. On the basis of these data, strict adherence to electrodiagnostic studies to confirm the diagnosis will exclude 13 percent of the patients with legitimate carpal tunnel syndrome from receiving appropriate therapy.