Sensors measure surface ablation rate of reentry vehicle heat shield

Sensors measure surface erosion rate of ablating material in reentry vehicle heat shield. Each sensor, which is placed at precise depths in the heat shield is activated when the ablator surface erodes to the location of a sensing point. Sensor depth and activation time determine ablator surface erosion rate

10 THz Ultrafast Function Generator - generation of rectangular and triangular pulse trains-

We report the synthesis of arbitrary optical waveforms by manipulating the spectral phases of Raman sidebands with a wide frequency spacing line-by-line. Trains of rectangular and triangular pulses are stably produced at an ultrahigh repetition rate of 10.6229 THz, reminiscent of an ultrafast function generator.Comment: 7 Pages, 5 Figure

PDEs with Compressed Solutions

Sparsity plays a central role in recent developments in signal processing, linear algebra, statistics, optimization, and other fields. In these developments, sparsity is promoted through the addition of an $L^1$ norm (or related quantity) as a constraint or penalty in a variational principle. We apply this approach to partial differential equations that come from a variational quantity, either by minimization (to obtain an elliptic PDE) or by gradient flow (to obtain a parabolic PDE). Also, we show that some PDEs can be rewritten in an $L^1$ form, such as the divisible sandpile problem and signum-Gordon. Addition of an $L^1$ term in the variational principle leads to a modified PDE where a subgradient term appears. It is known that modified PDEs of this form will often have solutions with compact support, which corresponds to the discrete solution being sparse. We show that this is advantageous numerically through the use of efficient algorithms for solving $L^1$ based problems.Comment: 21 pages, 15 figure

The Superintendent’s Point of View Concerning the High School Music Program in the Public Schools of Washington State

In the interest of better music programs and to further the communication between school music educators and their administrators, it will be the purpose of this study to discuss and investigate the high school music program from the superintendent’s point of view. The philosophies and convictions of 200 superintendents in the State of Washington will be utilized in this study

The Effects of Inter-particle Attractions on Colloidal Sedimentation

We use a mesoscopic simulation technique to study the effect of short-ranged inter-particle attraction on the steady-state sedimentation of colloidal suspensions. Attractions increase the average sedimentation velocity $v_s$ compared to the pure hard-sphere case, and for strong enough attractions, a non-monotonic dependence on the packing fraction $\phi$ with a maximum velocity at intermediate $\phi$ is observed. Attractions also strongly enhance hydrodynamic velocity fluctuations, which show a pronounced maximum size as a function of $\phi$. These results are linked to a complex interplay between hydrodynamics and the formation and break-up of transient many-particle clusters.Comment: 4 pages 4 figure

Evaluation of Dimethyl Anthranilate as a Nontoxic Starling Repellent for Feedlot Settings

Few objective estimates are available, but starling (Sturnus uulgaris) and, sometimes, blackbird (e.g., Agelaius phoeniceus) depredations at feedlots are considered serious economic problems (Besser et al. 1967, 1968; Feare 1975, 1980; Stickley 1979; Twedt and Glahn 1982). Losses may result either from feed contamination and disease transmission or, more likely, from feed consumption (Besser et al. 1968; Russell 1975; Twedt and Glahn 1982). These problems are exacerbated by the use of complete diets (Rickaby 1978) which are presented in open troughs to which starlings have access. Feare and Wadsworth (1981) have shown that these birds can take up to 9% of the high protein fraction of the diet, thus depriving cattle of their high energy source and altering the composition of the entire ration. Efforts to control problem birds at feedlots have focused mainly on attempts to trap or kill birds with mechanical devices or chemical agents (Besser et al. 1967; Bogadich 1968; Levingston 1967; Westetal.1967; Feareetal.1981). These approaches, however, fail to create a suboptimal environment for avian feeding activity, and birds rapidly reinfest feedlots when control measures are relaxed (Twedt and Glahn 1982). Additional problems arise when lethal chemicals; such as Starlicide (1% C-chloro-p-toludine hydrochloride on poultry pellets) are used, including: (1) potential primary and secondary hazards to nontarget animals (e.g., Cunningham, 1979), (2) bait aversion by target birds, (3) expense and labor in prebaiting, baiting and monitoring (Glahn 1981) and (5) rather short-term effectivenses when large numbers of birds are in the area (Feare et al. 1981)

Reverse-selective diffusion in nanocomposite membranes

The permeability of certain polymer membranes with impenetrable nanoinclusions increases with the particle volume fraction (Merkel et al., Science, 296, 2002). This intriguing observation contradicts even qualitative expectations based on Maxwell's classical theory of conduction/diffusion in composites with homogeneous phases. This letter presents a simple theoretical interpretation based on classical models of diffusion and polymer physics. An essential feature of the theory is a polymer-segment depletion layer at the inclusion-polymer interface. The accompanying increase in free volume leads to a significant increase in the local penetrant diffusivity, which, in turn, increases the bulk permeability while exhibiting reverse selectivity. This model captures the observed dependence of the bulk permeability on the inclusion size and volume fraction, providing a straightforward connection between membrane microstructure and performance

Studies in physiological undernourishment in sheep

1. An examination of changes in weight and body composition in a flock of free -grazing Scottish Blackface ewes indicated that, during the greater part of pregnancy, these ewes were undernourished and catabolizing considerable amounts of body tissue.2. The nutritional states of ewes from two differently managed Scottish Blackface flocks were characterized during late pregnancy in terms of circulating concentrations of plasma free fatty acids and ketones. Marked undernourishment was evident in both situations.3. Data collected in a variety of situations supported the hypothesis that the severity of undernourishment during late pregnancy is determined principally by foetal weight and the level of food intake. Within a group of pregnant ewes with comparable intakes, the general degree of undernourishment is dependent on the level of intake, and the relative severity of undernourishment in individual animals is determined by differences in foetal weight.4. The use of certain biochemical parameters as indices of undernourishment was examined in ewes with artificially induced hypoglycaemia. It was concluded that nutritional state is best characterized in terms of that parameter which shows the greatest response per unit change in either nutrient intake or nutrient requirement.5. Biochemical parameters were used to control the nutritional states of individual animals in an experiment on the effects of undernourishment during pregnancy on lamb birth- weight. The results of this experiment indicated that the undernourishment occurring in free- grazing hill ewes during late pregnancy was likely to reduce the birth - weight of single lambs by 10%, and that of twins by 25%.6. The additional energy requirements during pregnancy were estimated to be 100g digestible organic matter per kg foetus