Ultrasonic study of the temperature and pressure dependences of the elastic properties of a single-crystal Heusler structure Cu41Mn20Al39 alloy

Pulse-echo-overlap measurements of ultrasonic wave velocity have been used to determine the elastic-stiffness tensor components Cu and the adiabatic bulk modulus, BS, of a ferromagnetic Heusler structure Cu41Mn20Al39 at % alloy single crystal as functions of temperature in the range 14–300 K and hydrostatic pressure up to 0.2 GPa at room temperature. At 295 K the elastic stiffnesses are: C11=133 GPa, C44=92 GPa, C (=(C11–C12)/2)=17 GPa, C12=99 GPa, CL(=C11+C44–C)=205 GPa, and BS (=C11–4C/3)=106 GPa. Cu41Mn20Al39 is a comparatively soft material elastically because its elastic properties are influenced strongly by magnetoelastic effects. The results of measurements of the effects of hydrostatic pressure on the ultrasonic wave velocity have been used to obtain the hydrostatic-pressure derivatives of the elastic – stiffness tensor components. At 295 K (C11/P)P=0, (C44/P)P=0, (C/P)P=0, (C12/P)P=0, (CL/P)P=0, and (BS/P)P=0 are 5.0±0.1, 3.0±0.1, 1.0±0.2, 3.0±0.3, 7.7±0.4 and 3.7±0.4, respectively. Application of hydrostatic pressure does not induce acoustic-mode softening: the pressure derivatives (CIJ/P)P=0 and (BS/P)P=0 and the acoustic-mode Grüneisen parameters are positive. An interesting feature of the non-linear acoustic behaviour of this alloy is that the value obtained for (C/P)P=0, associated with the softer shear mode propagated along the [1 1 0] direction and polarized along the [1 1 0] direction, is small in comparison with those of the other shear and longitudinal modes. The Grüneisen parameter of this mode, and hence its vibrational anharmonicity, is much larger than those of the other long-wavelength acoustic phonon modes. © 1998 Kluwer Academic Publishers     

Effect of fenfluramine on food intake, mood, and performance of humans living in a residential laboratory

Five male and four female normal weight research volunteers, participating in 13-day residential studies, received oral fenfluramine (20, 40 mg) or placebo at 09:30 and 17:00. Food intake, performance, and subjective ratings were measured throughout the day. Carbohydrate intake was manipulated by providing lunch meals high (males: 120 g; females: 80 g) or low (males: 25 g; females: 16 g) in carbohydrate on 8 days; on the remaining days subjects self-selected lunch. Total caloric intake (approximately 2800 Kcal) did not differ among the low- and high-carbohydrate, and self-selected lunch conditions when subjects received placebo, indicating caloric compensation. Total carbohydrate intake was significantly less, however, when subjects consumed the low-carbohydrate lunch compared to the other lunch conditions. Fenfluramine significantly decreased total caloric intake (approximately 500 kcal) by decreasing meal size, not number, only when subjects consumed the low-carbohydrate lunch. Fenfluramine was only an effective anorectic drug when subjects consumed a lunch with fewer calories and a lower carbohydrate:protein ratio than self-selected baseline. Also, fenfluramine improved performance on a range of computer tasks and increased ratings of "Alert," "Friendly," and "Talkative," while decreasing ratings of "Tired" and "Irritable."     

A-IMilano apoprotein. Decreased high density lipoprotein cholesterol levels with significant lipoprotein modifications and without clinical atherosclerosis in an Italian family

Significant hypertriglyceridemia with a very marked decrease of high density lipoproteins (HDL)-cholesterol levels (7-14 mg/dl) was detected in three members (father, son, and daughter) of an Italian family. The three affected individuals did not show any clinical signs of atherosclerosis, nor was the atherosclerotic disease significantly present in the family. Lipoprotein lipase and lecithin:cholesterol acyltransferase activites were normal or slightly reduced. Morphological and compositional studies of HDL in the subjects showed a significant enlargement of the lipoprotein particles (approximately 120 vs. approximately 94 A for control HDL) and a concomitant increase in the triglyceride content. Analytical isoelectric focusing of HDL apoproteins provided evidence for multiple isoproteins in the apoprotein(apo)-A-I range, with nine different bands being detected instead of the usual four bands observed in normal subjects. Two-dimensional immunoelectrophoresis against apo-A antiserum indicated a clear reduction of apo-A in the alpha electrophoretic region, with splitting of the protein "peak." The observation in otherwise clinically healthy subjects of hypertriglyceridemia, reduced HDL-cholesterol, and marked apoprotein abnormalities, without a significant incidence of atherosclerotic disease in the family suggests this is a new disease entity in the field of lipoprotein pathology, very probably related to an altered amino acid composition of the apo-A-I protein (see Weisgraber et al. 1980. J. Clin. Invest. 66: 901-907).     

DISTRIBUTION AND ABUNDANCE OF STREAM FISHES IN RELATION TO BARRIERS: IMPLICATIONS FOR MONITORING STREAM RECOVERY AFTER BARRIER REMOVAL

Dams are ubiquitous in coastal regions and have altered stream habitats and the distribution and abundance of stream fishes in those habitats by disrupting hydrology, temperature regime and habitat connectivity. Dam removal is a common restoration tool, but often the response of the fish assemblage is not monitored rigorously. Sedgeunkedunk Stream, a small tributary to the Penobscot River (Maine, USA), has been the focus of a restoration effort that includes the removal of two low‐head dams. In this study, we quantified fish assemblage metrics along a longitudinal gradient in Sedgeunkedunk Stream and also in a nearby reference stream. By establishing pre‐removal baseline conditions and associated variability and the conditions and variability immediately following removal, we can characterize future changes in the system associated with dam removal. Over 2 years prior to dam removal, species richness and abundance in Sedgeunkedunk Stream were highest downstream of the lowest dam, lowest immediately upstream of that dam and intermediate farther upstream; patterns were similar in the reference stream. Although seasonal and annual variation in metrics within each site was substantial, the overall upstream‐to‐downstream pattern along the stream gradient was remarkably consistent prior to dam removal. Immediately after dam removal, we saw significant decreases in richness and abundance downstream of the former dam site and a corresponding increase in fish abundance upstream of the former dam site. No such changes occurred in reference sites. Our results show that by quantifying baseline conditions in a small stream before restoration, the effects of stream restoration efforts on fish assemblages can be monitored successfully. These data set the stage for the long‐term assessment of Sedgeunkedunk Stream and provide a simple methodology for assessment in other restoration projects. Copyright © 2011 John Wiley & Sons, Ltd.     

A high-field adiabatic fast passage ultracold neutron spin flipper for the UCNA experiment

The UCNA collaboration is making a precision measurement of the β asymmetry (A) in free neutron decay using polarized ultracold neutrons (UCN). A critical component of this experiment is an adiabatic fast passage neutron spin flipper capable of efficient operation in ambient magnetic fields on the order of 1 T. The requirement that it operate in a high field necessitated the construction of a free neutron spin flipper based, for the first time, on a birdcage resonator. The design, construction, and initial testing of this spin flipper prior to its use in the first measurement of A with UCN during the 2007 run cycle of the Los Alamos Neutron Science Center's 800 MeV proton accelerator is detailed. These studies determined the flipping efficiency of the device, averaged over the UCN spectrum present at the location of the spin flipper, to be ε=0.9985(4).     

Electronic window dressing: impression management with Websites

Businesses have embraced the Internet to reap economic advantages through the use of Websites. Most Website design guidelines fail to address issues of branding and identity formation, focusing instead on concerns adapted from previous technologies. However, many firms are not getting their desired results from the Website investments they have made following design guidelines reflecting graphic layout and system usability issues. We suggest that Websites should be considered ‘electronic storefronts’ or public work areas providing frames of symbolic representations that create impressions of their sponsoring firms. Our exploratory study shows that Websites influence potential customers' impressions of firms' legitimacy, innovation and caring, and that these impressions vary significantly across firms and industries. Website visitors encounter symbols that are compared to mental models stored in memory and used to form impressions of the site and to draw inferences about the firm. These inferences have previously been found to influence purchasing behavior. Designers should be cognizant of these aspects of e-Business and executives should recognize the power of Web-based impression management. Identity management must take center stage in creating a Web presence.     

Using a microprocessor-based instrument to predict the incident energy from arc-flash hazards

With better understanding of arc flashes, the electrical safety industry continues to develop new safety procedures for electrical workspaces. To assess the potential arc hazards of a workspace, workers must rely on engineering fault studies to provide vital fault-current data. An instrument, based on a network impedance analyzer, determines the maximum flash-arc incident-energy exposure at a worksite within a few seconds. The digital analyzer measures the power system source impedance, X/R ratio, and the system voltage to predict the bolted fault current and incident energy, while the power distribution system is energized and in normal operation. The instrument computes the incident energy for standard electrical workspaces of an open-air arc and an enclosed box with one open side. Experiments have been conducted to verify the accuracy of the impedance and X/R ratio measurements.     

Possible Phase Transition at Low mK Temperatures in Liquid Helium Mixture Films Adsorbed on Graphite

We report heat capacity and magnetisation measurements of ³He adsorbed on the surface of graphite plated with three atomic layers of ⁴He. For ³He coverages n ₃>4 nm^?2 the heat capacity corresponds to a 2D Fermi fluid. The inferred hydrodynamic mass of the ³He quasiparticles is 1.38±0.05 m₃. The ³He effective mass ratio increases with coverage to 2.4 at n ₃=4 nm^?2, due to Fermi liquid interactions. The heat capacity isotherm exhibits a steplike increase centred on n ₃=4.5 nm^?2, similar to that previously observed on four layers of ⁴He. This is associated with the population of the first excited Andreev surface bound state. However, in the present case, as n ₃ is increased through the step a pronounced anomalous feature develops in the temperature dependence of the heat capacity, around 10 mK. Below 5 mK the heat capacity is approximately linear in temperature. With n ₃=7 nm^?2, we find that this behaviour is very sensitive to small changes in the ⁴He third layer coverage, around the completed third layer. Measurements of the ³He magnetisation,, by continuous wave NMR methods, find a significant increase with decreasing temperature below around 20 mK. Together the data suggest that a phase transition takes place in the film at low mK temperatures.     

On the Determination of a Safe Life for Distributions Classified by Failure Rate

If the distribution of life length is a member of a specified subset of distributions which have increasing failure rates, we find a method of determining functions of the sample data which can be used to provide lower tolerance bounds of given confidence or a service life with specified assurance of no failures among a given number of items to be produced.

The method of finding such functions of the observations is shown to be optimal in a sense and the calculation of a lower bound for the probability of no failure in the future production is carried out when such functions are used. The confidence in the tolerance bound and the assurance of no failure in a production lot of specified size are compared when using bounds obtained from these functions.     

Algorithmic estimation of risk factors in financial markets with stochastic drift

We assume a financial market governed by a diffusion process reverting to a stochastic mean which is itself governed by an unobservable ergodic diffusion, similar to those observed in electricity and other energy markets. We develop a moment method algorithm for the estimation of the parameters of both the observable process and the unobservable stochastic mean. Our approach is contrasted with other methods for parameter estimation of partially observed diffusions, and applications to the modelling of interest rates and commodity prices are discussed.