Multiple time-scale diffusion models of starfish and coral state changes over the whole great barrier reef

A model is developed to investigate starfish and coral dynamics at the macro-scale of the whole Great Barrier Reef. This stochastic near-equilibrium theory is consistent with all available data for the mean rates of change of reef-state relative to abundances of the starfishAcanthaster planci and the scleractinian corals upon which it preys. This result is in striking contrast to the stably cyclic behaviour which dominates the meso-scale of individual reefs as reported previously by the authors. For the first time, a number of important numerical estimates have been made and are reported here. Generally, the starfish dynamics is dominated by randomness, being indistinguishable from Brownian motion in the state-space. On the other hand, the coral process is embedded in a drift field which is always directed towards the low coral state. In fact, the high coral state is inaccessible on the Great Barrier Reef.     

Planned versus actual duration of drug abuse treatment. Reconciling observational and experimental evidence

The purpose of the study was to evaluate the associations of planned versus actual duration of drug abuse treatment with psychosocial outcomes and drug use at follow-up. A randomized trial was conducted in a modified therapeutic community in which 444 clients were assigned to programs with planned durations of either 3 or 6 months. Outcomes were psychosocial measures assessing changes in mood and in stage of behavior change between admission and exit and return to drug use and patterns of use 2 to 6 months after exit. Planned duration was not associated with any of the outcomes. A longer actual length of stay was, however, associated with greater improvements in the mood variables; lower rates of drug use at follow-up; and, among those using drugs at follow-up, a longer time from exit to first drug use. Intention-to-treat analyses supported these results. Randomized controlled trials are needed to distinguish the effects of planned duration and actual length of stay.     

Spatial retardation of carrier heating in scaled 0.1-μmn-MOSFET's using Monte Carlo simulations

A comprehensive Monte Carlo simulator is employed to investigate nonlocal carrier transport in 0.1 μm n-MOSFET's under low-voltage stress. Specifically, the role of electron-electron (e-e) interactions on hot electron injection is explored for two emerging device designs biased at a drain voltage V_d considerably less than the Si/SiO₂ injection barrier height φ_b. Simulation of both devices reveal that 1) although qV_d<φ_b, carriers can obtain energies greater than φ_b, and 2) the peak for electron injection is displaced approximately 20 nm beyond the peak in the parallel channel electric field. These phenomena constitute a spatial retardation of carrier heating that is strongly influenced by e-e interactions near the drain edge. (Virtually no injection is observed in our simulations when e-e scattering is not considered.) Simulations also show that an aggressive design based on larger dopant atoms, steeper doping gradients, and a self-aligned junction counter-doping process produces a higher peak in the channel electric field, a hotter carrier energy distribution, and a greater total electron injection rate into the oxide when compared to a more conventionally-doped design. The impact of spatially retarded carrier heating on hot-electron-induced device degradation is further examined by coupling an interface state distribution obtained from Monte Carlo simulations with a drift-diffusion simulator. Because of retarded carrier heating, the interface states are mainly generated further over the drain region where interface charge produces minimal degradation. Thus, surprisingly, both 0.1 μm n-MOSFET designs exhibit comparable drain current degradation rates     

Micron-size particle filtration with dual wire artificial electretfibers

The authors present the construction, operation, and test results of a new type of electrostatic filter of very low pressure drop at usual flow-through velocities while providing excellent filtration for micron-size particles. The filter is constructed in the form of a thick mesh of dual wire fibers, electrically energized at approximately 200 V DC, and reversing the polarity at a very low frequency in the order of 5 mHz. While, in general, mechanical filters trap the particles on the air incoming surface, with subsequent rapid “blinding,” the new filter collects the particles inside the mesh volume thus offering a considerably longer life     

Solidification Behavior of Undercooled Liquid Aluminum Oxide

Solidification of aluminum oxide from undercooled melts was investigated in containerless experiments. Specimens were levitated in a gas jet, stabilized with an acoustic positioning device, and melted with cw CO₂ laser beams. Cooling curves were obtained by optical pyrometry when the laser intensity was reduced. The materials examined were high-purity Verneuil sapphire, 99.5% polycrystalline alumina, and oxide materials recovered from the effluent of an aluminum-fueled rocket motor. The degree of undercooling, the apparent temperature behavior during the thermal arrest on solidification, and the structure of the materials formed were different in argon and oxygen atmospheres. Undercooling of the sapphire and alumina materials was 360 ± 10 K in an oxygen atmosphere and approximately 450 K in argon. Melting and solidification of high-purity sapphire resulted in a dendritic and porous polycrystalline material in oxygen. Dense, larger crystals were obtained in argon. Products formed from 99.5% alumina were discolored and the cores were white, indicating impurity segregation effects. More reproducible behavior was observed for the sapphire and 99.5% alumina than for the tungstencontaminated rocket motor effluent materials.     

Voluntary and professional disaster-workers: similarities and differences in reactions

Forty-three rescuers responding to a bus crash that killed 12 children and 4 adults and injured many more answered questionnaires at 1 and 13 months following the crash. This study compared the responses of the voluntary and professional helpers, using the Impact of Event Scale (IES) and the General Health Questionnaire (GHQ). For all helpers taken together, the decline in IES-intrusion and IES-total scores was significant from 1 to 13 months. The voluntary helpers reported significantly more intrusion and avoidance on the IES at 1 month than professional helpers, and for avoidance the voluntary helpers still evidenced a significantly higher score than professional helpers at 13 months. The GHQ scores at 13 months reflected that the long-term negative impact of the event was low.     

Phase I trial of inhaled natural interleukin 2 for treatment of pulmonary malignancy: toxicity, pharmacokinetics, and biological effects

Safety, local and systemic immunomodulation, and tumor response to treatment with aerosolized natural interleukin 2 (nIL-2) applied five times a day were studied in a Phase I trial in 16 patients with pulmonary malignancies refractory to conventional therapy. The toxicity of inhaled nIL-2 was different from that observed after systemic administration. Reversible airway irritation causing a nonproductive cough represented the dose-limiting toxicity. Mild to moderate reduction of the vital capacity and forced expiratory volume (FEV1) with minor effects on relative FEV1, peak expiratory flow, airway resistance, and PaO2 was experienced by individual patients. In 14 patients suffering from pulmonary metastases due to renal cell cancer, one durable complete response, one partial response, and one mixed response were observed. Inhalation of nIL-2 aerosol resulted in a dose-dependent expansion of pulmonary immunocompetent cells in bronchoalveolar lavage fluid. Posttreatment bronchoalveolar lavage showed an activated lymphocyte phenotype with increased HLA-DR expression. The only systemic biological effect detectable in peripheral blood was a marked increase of soluble interleukin 2 receptor serum levels. We conclude that treatment with aerosolized nIL-2 is an effective means for site-specific immunomodulation and deserves further investigation for the treatment of malignant and inflammatory lung disease.     

Influence of joint detail on the flexural/torsional interaction of thin-walled structures

For a structure formed from two thin-walled open members connected at 90°, torsion applied to one member can result in torsion as well as flexure in the second member, with the magnitude and direction of this torsion as well as flexure in the second member being determined by the type of joint used. Conventional structural analysis would normally assume the presence of only flexure in the second member. The results from a finite element study of structures formed from thin-walled channel sections connected by box, mitre and stiffened mitre joints is presented and an explanation for the behaviour of the different joint types is given. It is shown that for the box joint the warping deformation of the loaded member is the dominant factor in determining the magnitude and direction of the twisting of the second member, whilst this is determined for the stiffened mitre joint primarily by the St Venant rotation deformation of the loaded member. For the unstiffened joint it is shown that the warping and St Venant rotation deformation effects tend to cancel each other out.