Noise in a point-contact dc SQUID

Measurements of five variations of a toroidal point-contact dc superconducting quantum interference device (SQUID) are presented. The energy resolution and other parameters of these SQUIDs are examined and compared with the predictions of the Resistively Shunted Junction model. For these SQUIDs, the measured minimum energy resolution was approximately 2×10^–30 J/Hz. Excess noise in the point contacts was found to limit the energy resolution of the SQUIDs. A comparison between the typical junction parameters and noise obtained for our niobium-niobium point contacts and those of others is given. TheI–V characteristics of the junctions showed the effects of Joule heating. The white voltage noise spectral density was found to have an approximately parabolic dependence on the average voltage for bias currents larger than the critical current. While this parabolic dependence is consistent with heating effects in the junctions, the amplitude of the noise cannot be explained in terms of a heating model. The low-frequency noise of the point contacts has also been investigated.     

Attempted preparation of Ti-6-4 alloy powders from TiCl4, Al,VCl4, and Na

The preparation of prealloyed titanium-6 pct aluminum-4 pct vanadium (Ti-6Al-4V) powder was attempted using TiCl₄, VCl₄, powdered Al, and sodium in a Hurd Shaker apparatus. The reduction reactions was monitored by following the light flash, pressure, and temperature increase. The data from each of these variables were collected with a PDP-11 computer as a function of time. These data show the reaction to be explosive and extremely discontinuous. Powder morphology and chemical composition were studied as a function of reaction conditions. Powder size, shape, and yield were highly dependent on the quantity of reactants and reactant distribution. The chemical composition of the powder was variable with particles having a range of Al and V compositions depending on the reactant conditions.     

Analysis of interinjection-locked oscillators for integrated phased arrays

The behavior of a system of coupled oscillators is shown to have potential applications in the generation of power for integrated phased antenna arrays. Nonlinear differential equations are derived to describe a system of oscillators coupled by an arbitrary frequency-dependent network. State-variable analysis of the linearized equations leads to closed-form solutions for one- and two-dimensional phased array systems. Experimental data for a VHF prototype system is presented, and practical considerations in system design are discussed.     

When reality monitoring fails: The role of imagination in stereotype maintenance.

Research on reality monitoring (the process by which people distinguish memories of real events from memories of imagined events) suggests that the occurrence of imagined events can inflate the perceived frequency of corresponding real events. Two experiments examined how such failures in reality monitoring can contribute to the maintenance of social stereotypes. When subjects imagined members of occupational groups in the initial experiment, they tended to incorporate stereotyped traits into their imaginations, with specific traits determined by the contexts being imagined. This suggests that imagined events do correspond with stereotype-confirming real events. In the second experiment, subjects read sentences that presented traits (stereotyped and nonstereotyped) in association with occupations with uniform frequency. They also imagined members of each occupation in situations relevant to particular stereotypic traits. In subsequent judgments of presentation frequency, subjects overestimated their exposure to stereotypic occupation–trait combinations, which replicated earlier studies. Subjects further overestimated the presentation frequency of imagined stereotypic combinations, which indicated the failure to distinguish self-generated images from actual presentations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impulsive impedances in lossless circuits: Fourier and Laplacemethods

A proposal for adding impulsive components of impedance/admittance to the reactance/susceptance for lossless transmission lines is extended to all lossless resonant circuits. This new Fourier analysis yields a finite rate of energy transfer from a lossless source while the orthodox analysis would give an unbounded steady-state energy transfer. Laplace transforms help to resolve this paradox     

RAPID PREDICTION OF MALT HOT WATER EXTRACT BY NEAR INFRARED REFLECTANCE SPECTROSCOPY STUDIES ON BARLEY

In recent years there has been an increasing awareness of the need for rapid screening tests for malting quality in barley. An infrared reflectance instrument has been calibrated against malt hot water extract (HWE). Results suggest that this type of instrument can be used to estimate HWE on barley and that this might provide a suitable screening method for use in a breeding programme. Greater accuracy is achieved if separate calibrations are made for winter and spring barleys and the correlation coefficients with HWE were 0.70 (n = 168) and 0.82 (n = 134) respectively.     

Classification and rule induction using rough set theory

Rough set theory (RST) offers an interesting and novel approach both to the generation of rules for use in expert systems and to the traditional statistical task of classification. The method is based on a novel classification metric, implemented as upper and lower approximations of a set and more generally in terms of positive, negative and boundary regions. Classification accuracy, which may be set by the decision maker, is measured in terms of conditional probabilities for equivalence classes, and the method involves a search for subsets of attributes (called 'reducts') which do not require a loss of classification quality. To illustrate the technique, RST is employed within a state level comparison of education expenditure in the USA.     

Evaluation of prescription opioids using operant-based pain measures in rats.

Opioids are the most effective compounds available for the relief of pain, yet there are a number of side effects that are of great concern to clinicians. For example, opioids are powerful reinforcers, and the treatment of pain using opioids could lead to the development of addiction. In addition, there is an increasing body of literature demonstrating that the repeated administration of opioids could lead to a phenomenon called opioid-induced hyperalgesia (i.e., increased sensitivity to painful stimulation). Studies examining these potential adverse effects are necessary in the development of novel analgesics. Furthermore, most studies of pain sensitivity and pain relief use reflex-based procedures to identify analgesics; however, it is argued here that operant-based procedures provide measures that are more analogous to the human condition (i.e., the mechanisms of pain are similar to those in humans) and should be useful in the assessment of novel analgesics. A series of studies examining the effects of opioids and the influence of variables such as age are discussed to demonstrate the utility of this approach. (PsycINFO Database Record (c) 2010 APA, all rights reserved)