Zeeman splitting measurements of magnetic fields in iodine plasma.

Iodine is an attractive propellant for next generation ion thrusters. Laser induced fluorescence (LIF) is widely used with other propellant species as a non-perturbative technique for measuring flow for thruster prediction models. We apply LIF methods recently demonstrated for singly-ionized iodine to a magnetized plasma environment similar to those found in ion thrusters and in magnetically confined laboratory plasmas. We demonstrate the feasibility of remotely determining the local magnetic field from the Zeeman effect-split spectrum of I+.

Demonstration of confocal laser induced fluorescence at long focal lengths.

We add a collection path obscuration to a confocal telescope and confirm theoretical predictions of significant improvement in the longitudinal spatial localization. The improvements of spatial localization permitted an extension of the confocal telescope's focal length from 150 mm to 500 mm. At this longer focal length, millimeter-scale spatial localization is confirmed by comparing radial profiles of metastable state density obtained via confocal and conventional optical arrangements in a helicon source. The long focal length arrangement enables the measurement of argon neutral velocity distribution functions in the conventionally inaccessible region under a helicon source antenna.

Confocal laser induced fluorescence with comparable spatial localization to the conventional method.

We present measurements of ion velocity distributions obtained by laser induced fluorescence (LIF) using a single viewport in an argon plasma. A patent pending design, which we refer to as the confocal fluorescence telescope, combines large objective lenses with a large central obscuration and a spatial filter to achieve high spatial localization along the laser injection direction. Models of the injection and collection optics of the two assemblies are used to provide a theoretical estimate of the spatial localization of the confocal arrangement, which is taken to be the full width at half maximum of the spatial optical response. The new design achieves approximately 1.4 mm localization at a focal length of 148.7 mm, improving on previously published designs by an order of magnitude and approaching the localization achieved by the conventional method. The confocal method, however, does so without requiring a pair of separated, perpendicular optical paths. The confocal technique therefore eases the two window access requirement of the conventional method, extending the application of LIF to experiments where conventional LIF measurements have been impossible or difficult, or where multiple viewports are scarce.

Interferometric identification of a pre-brown dwarf.

It is not known whether brown dwarfs [stellar-like objects with masses less than the hydrogen-burning limit, 0.075 solar mass (M)[symbol:see text]] are formed in the same way as solar-type stars or by some other process. Here we report the clear-cut identification of a self-gravitating condensation of gas and dust with a mass in the brown-dwarf regime, made through millimeter interferometric observations. The level of thermal millimeter continuum emission detected from this object indicates a mass ~0.02 to 0.03 M[symbol:see text], whereas the small radius, <460 astronomical units, and narrow spectral lines imply a dynamical mass of 0.015 to 0.02 M[symbol:see text]. The identification of such a pre-brown dwarf core supports models according to which brown dwarfs are formed in the same manner as hydrogen-burning stars.

Cognitive functioning pre- to post-kidney transplantation--a prospective study.

BACKGROUND: Kidney transplantation (TX) may ameliorate the neuropsychological (NP) impairments in end-stage renal disease (ESRD). Previous studies have suffered from small sample sizes, lack of standardization of dialysis adequacy, and insufficiently sensitive NP tests. METHODS: Twenty-eight medically stable patients aged 44.04 (12.01) years with ESRD were investigated before and at 6 months after successful kidney TX using an NP test battery, which assessed attention-concentration, psychomotor ability and memory. Formal kinetic modelling of dialysis delivery ensured adequate renal replacement therapy. Transplant function was good on stable doses of immunosuppressive medication, without evidence of rejection at the time of testing. RESULTS: Within-subject comparisons showed statistically significant improvement in memory performance after kidney TX. Other NP measures (attention-concentration and psychomotor abilities) showed non-significant improvements. Normative comparisons showed NP impairments on dialysis, which were not apparent after TX. CONCLUSION: These data demonstrate improvements in cognition following kidney TX and emphasize the reversibility of the memory problems evidenced in dialysis.

Neuropsychological performance after kidney transplantation: a comparison between transplant types and in relation to dialysis and normative data.

BACKGROUND: Neuropsychological (NP) performance after kidney transplantation (TX) has received little attention. This study compared NP functioning between dialysis and transplant patients and between living-related donor (LRD) and cadaver (CAD) transplant recipients. The association between immunosuppressive medication and NP outcomes was also examined. METHODS: One hundred and seventeen transplant recipients (25 LRD and 92 CAD patients) and 145 dialysis patients (77 haemodialysis and 68 peritoneal dialysis) were administered an NP test battery to assess learning and verbal recall, attention and concentration, and psychomotor abilities/speed. Biochemical markers of renal function were also assessed. RESULTS: Overall, transplant patients showed normal cognitive functioning in all domains assessed. NP performance was found to be equivalent in both transplant groups and in patients on cyclosporin and those on tacrolimus. ANCOVAs showed that TX patients performed significantly better than dialysis patients on selective NP tests, i.e. the two memory tasks and two out of the four tests of attention. No differences were found in motor tasks. CONCLUSIONS: Our results reveal no evidence of NP deficits in TX patients. The NP advantage of TX relative to dialysis is evident mainly in verbal memory.

Acute neuropsychological changes in hemodialysis and peritoneal dialysis patients.

This study examined the impact of different dialysis treatments on the neuropsychological (NP) functioning of 145 end-stage renal disease patients. Hemodialysis (HD) and peritoneal dialysis (PD) patients were administered an NP test battery and measures of mood on 2 consecutive days (pre- and 24 hr postdialysis). Biochemistry was assessed at each session. Results indicated significant improvements in NP functioning (attention, concentration, verbal and visual memory, and psychomotor speed) in HD patients 24 hr postdialysis. No such fluctuations were found in PD patients. Although biochemical changes were found in the HD patients at the same time points, these were not consistently related to the NP changes.

A combined 14N/27Al nuclear magnetic resonance and powder X-ray diffraction study of impurity phases in beta-sialon ceramics.

Beta-sialons are ceramic phases occurring in the SiO(2)-Si(3)N(4)-AlN-Al(2)O(3) system. A series of samples with differing compositions has been investigated by magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy and powder X-ray diffraction (XRD). Although the constituent nitrogen nuclei occupy positions of low symmetry in the beta-sialon structure, 14N NMR spectra could be recorded for the samples examined. The origin of the 14N signal could be traced to the presence of an aluminium nitride (AlN) impurity phase with the help of 27Al NMR and XRD results. Similarly, the existence of Al(2)O(3) grains could be readily detected for a number of samples. Thus, the combination of 14N and 27Al NMR is shown to be an especially effective tool in identifying and characterizing impurity phases in sialon ceramics, complementing the results obtained from standard XRD analysis.

Quality of life and emotional responses in cadaver and living related renal transplant recipients.

BACKGROUND: The specific impact of transplantation on living related donor (LRD) and cadaver (CAD) kidney transplant recipients and their health-related quality of life (HQoL) has received little attention. This study examined the role of sociodemographic, medical and psychological factors in these two groups. METHODS: A total of 347 transplant recipients (76 LRD and 271 CAD patients) completed the Short Form 36 Health Survey and Transplant Effects Questionnaire. RESULTS: Overall, transplant patients showed satisfactory HQoL particularly with respect to emotional well being. HQoL levels were found to be equivalent in both transplant groups. ANCOVAs showed that LRD recipients expressed more guilt in relation to the donor (P<0.001). Multivariate analysis revealed that worry about the viability and functioning of the transplant alone predicted 15.1% of the variance in the SF-36 mental composite score (MCS) whereas age, income, comorbidities and time on dialysis explained 37.8% of the variance in the SF-36 physical composite score (PCS). Multiple regression analyses performed separately for LRD and CAD patients showed that predictors of MCS and PCS between the two groups were similar. CONCLUSIONS: Our results indicate that different forms of transplantation (LRD vs CAD) may lead to different emotional responses albeit with no apparent quality of life differences. In particular, feelings of guilt appear to be prominent in LRD transplantation.

Isolated star formation: from cloud formation to core collapse.

The formation of stars is one of the most fundamental problems in astrophysics, as it underlies many other questions, on scales from the formation of galaxies to the formation of the solar system. The physical processes involve the turbulent behavior of a partially ionized medium containing a non-uniform magnetic field. Current debate centers around the time taken for turbulence to decay and the relative importance of the roles played by magnetic fields and turbulence. Technological advances such as millimeter-wave cameras have made possible observations of the temperature and density profiles, and statistical calculations of the lifetimes, of objects collapsing under their own self-gravity and those on the verge of collapse. Increased computing power allows more complex models to be made that include magnetic and turbulent effects. No current model can reproduce all of the observations.