The effects of change in lead stimulus modality on the modulation of acoustic blink startle

In two experiments we investigated the effect of generalized orienting induced by changing the modality of the lead stimulus on the modulation of blink reflexes elicited by acoustic stimuli. In Experiment 1 (n = 32), participants were presented with acoustic or visual change stimuli after habituation training with tactile lead stimuli. In Experiment 2 (n = 64), modality of the lead stimulus (acoustic vs. visual) was crossed with experimental condition (change vs. no change). Lead stimulus change resulted in increased electrodermal orienting in both experiments. Blink latency shortening and blink magnitude facilitation increased from habituation to change trials regardless of whether the change stimulus was presented in the same or in a different modality as the reflex-eliciting stimulus. These results are not consistent with modality-specific accounts of attentional startle modulation.

Effects of an oral vasopressin receptor antagonist (OPC-31260) in a dog with syndrome of inappropriate secretion of antidiuretic hormone

Objective The syndrome of inappropriate secretion of antidiuretic hormone is a rare disorder in dogs characterised by hypo-osmolality and persistent arginine vasopressin production in the absence of hypovolaemia and/or hypotension. The study describes the efficacy and safety of the nonpeptide selective arginine vasopressin V-2 receptor antagonist OPC-31260 in a dog with the naturally occurring syndrome. Design The detailed case history of a dog with spontaneous syndrome of inappropriate secretion of antidiuretic hormone that received long-term therapy with oral OPC-31260 is presented. Effects of the first dose of OPC-31260 and of a dose administered after a continuous dosing period of 12 days are reported. Procedure Packed cell volume, plasma sodium, total protein, arginine vasopressin, renin activity, atrial natriuretic peptide, urine specific gravity, urine output, heart rate and body weight were monitored for 2 h before, and for 4 h after, the first dose of OPC-31260. The same parameters plus plasma osmolality and urine osmolality were monitored when an identical dose was administered after 12 days of therapy. Results Oral administration of OPC-31260 at 3 mg/kg body weight resulted in marked aquaresis with increased urine output and decline in urine specific gravity within 1 h. Corresponding increases in concentrations of plasma sodium, plasma osmolality and plasma renin activity were recorded over a 4 h period. Arginine vasopressin concentration remained inappropriately elevated throughout the study. Results were similar when the trial procedure was repeated after a stabilisation period of 12 days. Long-term therapy with OPC-31260 at a dose of 3 mg/kg body weight orally every 12 h resulted in good control of clinical signs with no deleterious effects detected during a 3-year follow-up period. Despite sustained clinical benefits observed in this case, plasma sodium did not normalise with continued administration of the drug. Conclusions Treatment of a dog with naturally occurring syndrome of inappropriate secretion of antidiuretic hormone with OPC-31260 at 3 mg/kg body weight orally every 12 h resulted in marked aquaresis and significant palliation of clinical signs with no discernible side-effects detected over a 3-year period. Thus, OPC-31260 appears to offer a feasible medical alternative to water restriction for treatment of dogs with syndrome of inappropriate secretion of antidiuretic hormone. Higher doses of OPC-31260 may be required to achieve and maintain normal plasma sodium in dogs with this syndrome.

Quantum spin ladder systems associated with su(2 vertical bar 2)

Two integrable quantum spin ladder systems will be introduced associated with the fundamental su(2 \2) solution of the Yang-Baxter equation. The first model is a generalized quantum Ising system with Ising rung interactions. In the second model the addition of extra interactions allows us to impose Heisenberg rung interactions without violating integrability. The existence of a Bethe ansatz solution for both models allows us to investigate the elementary excitations for antiferromagnetic rung couplings. We find that the first model does not show a gap whilst in the second case there is a gap for all positive values of the rung coupling.

Tidal fluctuations in a leaky confined aquifer: Dynamic effects of an overlying phreatic aquifer

Tidal fluctuations in a leaky confined coastal aquifer are damped significantly due to leakage into an overlying phreatic aquifer. Jiao and Tang [1999] presented an analytical solution to a simple model describing this phenomenon. Their solution assumes that the tidal fluctuations in the overlying phreatic aquifer are negligible (i.e,, a static phreatic aquifer), Here we examine dynamic effects of the overlying aquifer based on a new approximate analytical solution. The numerical results indicate that the dynamic effects can be significant for a relatively large leakage and a high transmissivity of the phreatic aquifer.

Immunosuppressive effects of melanoma-derived heavy-chain ferritin are dependent on stimulation of IL-10 production

Cultured melanoma cells release soluble factors that influence immune responses. Screening of a cDNA library with anti-sera from a melanoma patient identified an immunoreactive plaque, which encoded heavy-chain ferritin (H-ferritin), Previous studies have drawn attention to the immunosuppressive effects of this molecule and prompted further studies on its biochemical and functional properties in human melanoma, These studies demonstrated, firstly, that H-ferritin appeared to be secreted by melanoma cells, as shown by immunoprecipitation of a 21.5 kDa band from supernatants. It was also detected in extracts of melanoma cells by Western blotting as 43 and 64 kDa dimers and trimers of the 21.5 kDa fraction. Secondly, flow-cytometric analysis of H- and light-chain ferritin (L-ferritin) expression on melanoma showed a wide variation in L-ferritin expression and consequently of the ratio of H- to L-ferritin expression. Suppression of mitogenic responses of lymphocytes to anti-CD3 showed a correlation with the ratio of H- to L-ferritin in the supernatants and was specific for H-ferritin, as shown by inhibition studies with a monoclonal antibody (MAb) against H-ferritin, Similar results were obtained with H- and L-ferritin from other sources. Suppression of mitogenic responses of lymphocytes to anti-CD3 by H-ferritin was inhibited using a MAb against IL-IO, which suggested that the immunosuppressive effect of H-ferritin was mediated by IL-IO, Assays of cytokine production from anti-CD3-stimulated lymphocytes showed that H-ferritin markedly increased production of IL-10 and IFN-gamma and had only slight effects on IL-2 and IL-4 production, Our results suggest that melanoma cells may be a major source of H-ferritin and that production of the latter may account for some of the immunosuppressive effects of melanoma, (C) 2001 Wiley-Liss. Inc.

Race and sex effects on the association between muscle strength, soft tissue, and bone mineral density in healthy elders: The Health, Aging, and Body Composition Study

Two factors generally reported to influence bone density are body composition and muscle strength. However, it is unclear if these relationships are consistent across race and sex, especially in older persons. If differences do exist by race and/or sex, then strategies to maintain bone mass or minimize bone loss in older adults may need to be modified accordingly. Therefore, we examined the independent effects of bone mineral-free lean mass (LM), fat mass (FM), and muscle strength on regional and whole body bone mineral density (BMD) in a cohort of 2619 well-functioning older adults participating in the Health, Aging, and Body Composition (Health ABC) Study with complete measures. Participants included 738 white women, 599 black women, 827 white men, and 455 black men aged 70-79 years. BMD (g/cm(2)) of the femoral neck, whole body, upper and lower limb, and whole body and upper limb bone mineral-free LM and FM was assessed by dual-energy X-ray absorptiometry (DXA). Handgrip strength and knee extensor torque were determined by dynamometry. In analyses stratified by race and sex and adjusted for a number of confounders, LM was a significant (p < 0.001) determinant of BMD, except in white women for the lower limb and whole body. In women, FM also was an independent contributor to BMD at the femoral neck, and both PM and muscle strength contributed to limb BMD. The following were the respective Beta-weights (regression coefficients for standardized data, Std beta) and percent difference in BMD per unit (7.5 kg) LM: femoral neck, 0.202-0.386 and 4.7-6.9 %; lower limb,.0.209-0.357 and 2.9-3.5%; whole body, 0.239-0.484 and 3.0-4.7 %; and upper limb (unit = 0.5 kg), 0.231-0.407 and 3.1-3.4%. Adjusting for bone size (bone mineral apparent density [BMAD]) or body size BMD/height) diminished the importance of LM, and the contributory effect of FM became more pronounced. These results indicate that LM and FM were associated with bone mineral depending on the bone site and bone index used. Where differences did occur, they were primarily by sex not race. To preserve BMD, maintaining or increasing LM in the elderly would appear to be an appropriate strategy, regardless of race or sex.

Field-swept pulsed electron paramagnetic resonance of Cr3+-doped ZBLAN fluoride glass

Field-swept pulsed electron paramagnetic resonance (EPR) spectra of a ZBLAN fluoride glass doped with a low concentration of Cr3+ are obtained using echo-detected EPR and hole-burning free induction decay detection. We review the utility of the pulsed EPR technique in generating field-swept EPR spectra, as well as some of the distorting effects that are peculiar to the pulsed detection method. The application of this technique to Cr3+-doped ZBLAN reveals that much of the broad resonance extending from g(eff) = 5.1 to g(eff) = 1.97, characteristic of X-band continuous wave EPR of Cr3+ in glasses, is absent. We attribute this largely to the variation in nutation frequencies across the spectrum that result from sites possessing large fine structure interactions. The description of the spin dynamics of such sites is complicated and we discuss some possible approaches to the simulation of the pulsed EPR spectra.

BeachWin: modelling groundwater effects on swash sediment transport and beach profile changes

Field and laboratory observations have shown that a relatively low beach groundwater table enhances beach accretion. These observations have led to the beach dewatering technique (artificially lowering the beach water table) for combating beach erosion. Here we present a process-based numerical model that simulates the interacting wave motion on the beach. coastal groundwater flow, swash sediment transport and beach profile changes. Results of model simulations demonstrate that the model replicates accretionary effects of a low beach water table on beach profile changes and has the potential to become a tool for assessing the effectiveness of beach dewatering systems. (C) 2002 Elsevier Science Ltd. All rights reserved.

A director theory for visco-elastic folding instabilities in multilayered rock

A model for finely layered visco-elastic rock proposed by us in previous papers is revisited and generalized to include couple stresses. We begin with an outline of the governing equations for the standard continuum case and apply a computational simulation scheme suitable for problems involving very large deformations. We then consider buckling instabilities in a finite, rectangular domain. Embedded within this domain, parallel to the longer dimension we consider a stiff, layered beam under compression. We analyse folding up to 40% shortening. The standard continuum solution becomes unstable for extreme values of the shear/normal viscosity ratio. The instability is a consequence of the neglect of the bending stiffness/viscosity in the standard continuum model. We suggest considering these effects within the framework of a couple stress theory. Couple stress theories involve second order spatial derivatives of the velocities/displacements in the virtual work principle. To avoid C-1 continuity in the finite element formulation we introduce the spin of the cross sections of the individual layers as an independent variable and enforce equality to the spin of the unit normal vector to the layers (-the director of the layer system-) by means of a penalty method. We illustrate the convergence of the penalty method by means of numerical solutions of simple shears of an infinite layer for increasing values of the penalty parameter. For the shear problem we present solutions assuming that the internal layering is oriented orthogonal to the surfaces of the shear layer initially. For high values of the ratio of the normal-to the shear viscosity the deformation concentrates in thin bands around to the layer surfaces. The effect of couple stresses on the evolution of folds in layered structures is also investigated. (C) 2002 Elsevier Science Ltd. All rights reserved.

Tidal fluctuations in a leaky confined aquifer: localised effects of an overlying phreatic aquifer

Damping of tidal head fluctuations in a leaky confined coastal aquifer is enhanced by leakage into an overlying phreatic aquifer. We show that the phreatic aquifer is, however, resistant to the leakage flow and in particular, a deep phreatic aquifer can reduce the leakage effects significantly. An analytical solution, based on a vertical flow model for the phreatic aquifer, is derived for quantifying the role of this upper free water body in tidal propagation in the lower semi-confined aquifer. (C) 2002 Elsevier Science B.V. All rights reserved.