Salt-water up-coning during extraction of fresh water from a tropical island

Rainwater can collect in a lens-shaped region within the rock of a tropical island, and may be separated from the underlying salt water by a sharp interface. This paper presents a nonlinear theory for determining the shape of this interface. The island is assumed to be saturated with rain, and provision is made for the outflow of rain-water through the sides of the island. The effect of a bore well on the shape of the interface is investigated, and the problem is solved using a spectral method. An integral-equation method is also presented for the case when the island has infinite width.     

Flow due to a sink near a vertical wall, in infinitely deep fluid

Flow caused by a point sink in an otherwise stagnant fluid is studied using numerical methods based on integral-equation techniques and an asymptotic solution for small Froude number. There is a vertical wall present on a plane close to the sink, so that the flow is fully three dimensional. The fluid is of infinite depth, but a free-surface bounds it above. Steady solutions are presented for various Froude numbers and distances of the source from the wall. It is shown that the numerical results and asymptotic formula are in good agreement for small Froude numbers, but the results suggest that the non-linear solution ultimately forms some limiting structure at sufficiently large Froude number.     

Forced oscillations in an exothermic chemical reaction

We study non-linear behaviour in a model chemical reaction scheme (proposed by Sal?nikov), in which a single chemical species undergoes a two-stage, first-order decay process. The second stage is exothermic and has a temperature-dependent rate, and as a result, spontaneous oscillations in the temperature and the concentration of an intermediate chemical are known to be possible. An additional oscillation is imposed on the system by varying the ambient temperature in a sinusoidal manner. Primary resonance occurs when the forcing frequency coincides with the frequency of the natural oscillations in this scheme and an infinite sequence of super-and subharmonic resonances is also present. Chaos is possible for appropriate parameter values and may result either from the Feigenbaum period-doubling cascade, or else as a result of the Ruelle-Takens approach through quasi-periodicity.     

Physical model of drain conductance, gd, degradation ofNMOSFET's due to interface state generation by hot carrierinjection

Degradation of analog device parameters such as drain conductance, g_d, due to hot carrier injection has been modeled for NMOSFET's. In this modeling, mobility reduction caused by interface state generation by hot carrier injection and the gradual channel approximation were employed. It has been found that g_d degradation can be calculated from linear region transconductance, g_m, degradation which is usually monitored for hot carrier degradation of MOSFET's. The values of g_d degradation calculated from g_m degradation fit well to the measured values of g_d degradation The dependence of the g_d degradation lifetime on L_eff has been also studied, this model also provides an explanation of the dependence on L_eff. The model is then useful for lifetime predictions of analog circuits in which g_d degradation is usually more important than g_m degradation     

Treatment of Posttraumatic Stress Disorder in Military and Veteran Populations.

While concerns about the psychological effects of war are not new, only recently has systematic attention been paid to such problems among past and present military personnel. There is increasing recognition that mental health has serious implications for operational performance, retention, and compensation. Although little controlled research exists with this population, preliminary evidence suggests that psychological treatments for posttraumatic stress disorder may be beneficial, albeit less so than for civilian populations. This article reviews evidence for each of several psychological treatment stages: stabilization and engagement, psychoeducation, symptom management, prolonged exposure, cognitive restructuring, and relapse prevention, with particular reference to the clinical issues raised by military personnel. Possible explanations for reduced treatment effects in this population compared with civilians are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Unsteady free surface flow induced by a line sink in a fluid of finite depth

The unsteady withdrawal of fluid from a reservoir of finite depth with a free surface through a line sink is considered. A numerical method is used to investigate the evolution of a free surface in several different geometric and initial configurations, and it is shown that there are some critical flow parameters at which the flow changes its nature. The existence of steady states is also considered. Results both with and without surface tension are included and placed in context with previous work. Inclusion of surface tension reveals that solutions either evolve to a steady state or drawdown. As the sink is moved off the base, the behaviour becomes consistent with flows in a fluid of infinite depth, and consequently flows can be classified as either “shallow” or “deep” depending on their drawdown behaviour.     

Magnetic Relaxation of Solid and Liquid 3He Confined Inside a Silver Sinter

We present T ₁ measurements performed in liquid and solid ³ He confined in sintered silver. In the liquid case, we find a close to linear relationship between T ₁ and the applied magnetic field, similar to other (non metallic) systems, and up to higher frequencies (corresponding to 11 T) than previously reported. In the solid, the relaxation rate is found to increase spectacularly at large polarizations, which may indicate a polarization dependence of the exchange motion. Now atNow at