Free radicals in γ-irradiated PETN

An EPR investigation of-irradiated PETN (Pentaerythritol Tetranitrate) was conducted. Low temperature irradiation accumulates at least two different radicals. The more stable radical is the NO₂ radical presumably produced by photon cleavage of the NO₂ groups and/or by radical reactions in excited states resulting in detached NO₂. The spectrum of the more reactive radical is obtained by computer substraction. Decay kinetics are proposed for the NO₂ and the unknown highly reactive radical.     

Groundwater temperature and degassing in the Mad River subwatershed of Lake Huron

Groundwater was measured 70 times in two years at 10 sites as it flowed 50 m over an accumulation of travertine (CaCO₃) before reaching the Mad River. At source, the groundwater was relatively cool (6.77 ± 2.89 °C), slightly acidic ( pH 6.86 ± 0.22), and had a moderately high specific conductivity (606 ± 51 μS). Degassing was assessed from increases in pH, and CaCO₃ deposition was assessed from decreasing conductivity. After flowing over the experimental site, degassing had increased pH to 8.04 ± 0.16 (P < 0.001), which was similar to river water (pH 8.07 ± 0.30). Concurrently, CaCO₃ deposition decreased conductivity to 577 ± 43 μS (P < 0.001) but this was still higher (P < 0.001) than river water (494 ± 72). Seasonal changes in air temperature affected the rate of degassing. The pH was correlated with air temperature (r = 0.15, P < 0.001) while conductivity was correlated with pH (r = − 0.27, P < 0.001), but no direct relationship of air temperature with conductivity was detected. Groundwater entering the river after atmospheric exposure had a fairly constant temperature (7.05 ± 1.22 °C) despite seasonal changes in air temperature, thus warming the river in winter (up to day 100 and after day 300) and cooling it in summer (from days 140 to 260). Degassing and CaCO₃ deposition in springs without travertine was similar to that observed in the study stream over travertine. These groundwater inflows provide favorable pH and temperature conditions for brook trout.     

Probabilistic resource allocation in heterogeneous distributed systems with random failures

The problem of finding efficient workload distribution techniques is becoming increasingly important today for heterogeneous distributed systems where the availability of compute nodes may change spontaneously over time. Resource-allocation policies designed for such systems should maximize the performance and, at the same time, be robust against failure and recovery of compute nodes. Such a policy, based on the concepts of the Derman–Lieberman–Ross theorem, is proposed in this work, and is applied to a simulated model of a dedicated system composed of a set of heterogeneous image processing servers. Assuming that each image results in a “reward” if its processing is completed before a certain deadline, the goal for the resource allocation policy is to maximize the expected cumulative reward. An extensive analysis was done to study the performance of the proposed policy and compare it with the performance of some existing policies adapted to this environment. Our experiments conducted for various types of task-machine heterogeneity illustrate the potential of our method for solving resource allocation problems in a broad spectrum of distributed systems that experience high failure rates.     

Trail-following pheromones of the rhinotermitidae: Approaches to their authentication and specificity

A method for determining the authenticity of subterranean termite trail pheromones is suggested and utilized to verify the presence of trail pheromones inReticulitermes virginicus, R. flavipes, andR. tibialis. In addition, a possible trail pheromone has been demonstrated forCoptotermes formosanus. A choice bioassay method shows that the above trail pheromones are species specific.     

Interaction between radiation and drug damage in mammalian cells. II. The effect of actinomycin-D on the repair of the sublethal radiation damage in plateau phase cells

The effect of actinomycin-D (AMD) on radiation damage repair was studied in plateau phase V79 Chinese hamster cells. Sublethal radiation damage repair, as demonstrated by survival fluctuations following two x-ray exposures separted by time, was observed in our plateau phase cells. Plateau phase cells exposed to 0.01-0.04 mug/ml AMD (a nontoxic regimen to 8 hours) between x-ray exposures were less able to repair sublethal damage. If plateau phase cells were plated at low dilutions into fresh medium (conditions for resuming exponential growth) immediately after the first x-ray dose, and exposed to 0.01--0.04 mug/ml AMD until the second dose, inhibition of sublethal damage repair and additional cell killing were observed particularly at 0.04 mug/ml AMD. It is suggested that radiation-drug damage interactions should be studied in plateau phase cells and in cells resuming exponential growth after plateau phase (possibly analogous to "recruitment"), as well as in exponential phase cultures.     

Effects of hypothalamic temperature changes on the sweat rate in Macaca mulatta

The concept of cardiac reconditioning centers for the prevention and rehabilitation of coronary patients has been tremendously successful in Germany over the past 20 years. At least 40 such centers are located throughout the country. Physicians, nurses, and physical therapists work closely together in the various facets of the rehabilitation process. The financial backing for these facilities is primarily through governmental and regional insurance companies, whose officials are apparently convinced that in the long run supporting preventive measures is financially sound. Objective data supporting their convictions come from studies such as that of Brusis, who showed that such as that of 1,500 employees was diminished by nearly 70 percent during a two-year period after cardiac reconditioning, as compared to a similar time period before the rehabilitation experience. Subjective benefits, which are extremely difficult to quantitate in meaningful terms, were nonetheless expressed by nearly all the patients with whom I conversed. Perhaps they have experienced the same feelings that Mark Twain did when he observed that "all frets and worries and chafings sank to sleep in the presence of the benignant serenity of the Alps; the Great Spirit of the Mountains breathed his own peace upon their hurt minds and sore hearts and healed them."     

The emotional aftermath of adoption

Adopted children are emotionally vulnerable. Adoptive parents must cope with more complex problems than biologic parents. The family physician can provide valuable counseling. Preadoption counseling focuses on motivation and ambivalence. After adoption, however, serious, sometimes predictable, issues arise, such as: how and when to tell the child he is adopted; the child's search for knowledge; the problem of subsequent divorce; the birth of a natural sibling, and the involvement of other family members. New concepts include "open adoption" and "single parent adoption."     

Effect of gate poly-silicon depletion on MOSFET input impedance

One of the most challenging problems encountered in developing RF circuits is accurate prediction of MOS behavior at microwave signal and data frequencies. An attempt is made in this work to accurately model the device input impedance for the 1-20-GHz frequency range. The effect of device length and single-leg width on the input impedance is studied with the aid of extensive measured data obtained from devices built in 0.11-/spl mu/m and 0.18-/spl mu/m technologies. The measured data illustrates that the device input impedance has a nonlinear frequency dependency. It is also shown that this variation in input impedance is a result of gate poly-silicon depletion, which can be modeled by an external RC network connected at the gate of the device. Excellent agreement between the simulation results and the measured data validates the model in the device active region.