Experimental determination of the equation of state of solid hydrogen and deuterium at high pressures

Isochores of solid hydrogen and deuterium have been measured for melting line pressures up to 2000 bar. These are corrected to correspond to para-H₂ and ortho-D₂. The 4.2 K isotherm of H₂ has been determined and compared to the extrapolated low-pressure isochore of Anderson and Swenson (AS). Deviations have led us to reanalyze the AS data. The 4.2 K isotherm and the isochores are used, with the aid of a Mie-Grüneisen analysis, to determine P-V-T data for these solids up to 25 kbar. An analysis is presented which enables a determination of P-V-T-C ₁ for all values of C ₁, the ortho-para concentration. Results, including the Debye temperature, Grüneisen constant, and bulk modulus, are presented both in tabulated and graphical form. We also present what we feel to be the best of the 4.2 K, zero-pressure molar volumes of disordered H₂ and D₂ as a function of C ₁. Our measurements show no indication of the premelting phase transition reported in recent Russian literature and a possible explanation is presented.Supported in part by the Stichting FOM.     

An equivalent circuit characterization of power MOSFET accounting for high field and high frequency effects

An equivalent circuit model for analyzing the AC characteristics of power VDMOS transistors is presented. The model accounts for high field and saturation effects. This is achieved by incorporating dependent voltage and current sources in the device model. Results are given for the AC characteristics of a POLYFET F2001 Power VDMOSFET rated with a drain current of 1.4A, power out of 2.5W at 1GHz. The linear, quasi-saturation and saturation regions of the IV characteristics are accounted for in the analysis. The small signal device parasitics are extracted through s-parameter methods. The s-parameter results were used to extract the frequency dependent parasitics including parasitic capacitances, inductances and transconductances.     

Manufacture of High Performance Carbon Fibers from Precursors of Various Diameters

The effects of fiber diameter on the mechanical properties of PAN-based carbon fibers have been investigated in a series of processing experiments on fibers with different starting filament diameters. The fiber tows, with similar initial mechanical performance, were stretched at high temperatures to produce a large number of fiber types with a wide range of filament diameters. The three starting carbon fibers tows had nominal filament diameters of 5 μm, 6·5 μm, and 10 μm and contained 12000, 6000, and 3000 filaments respectively. These tows were stretched for 5 minutes at 2600^°C with a series of loads of up to 6 kg. For all fiber types and all stretching conditions, substantial increases in Young's moduli were induced, the increases being closely related to the induced extensions. However, it was found that tensile strengths generally decreased if fibers were subjected to high temperatures without significant stretching. On the other hand, the tensile strengths were restored to their original values when greater strains were induced by using higher stresses. Although fibers with a relatively large diameter of 8·3 μm were produced with a modulus of -470GPa and strength of -3·7 GPa, greater improvements in mechanical properties were achieved with smaller diameter fibers. The loads and temperatures involved in these hot stretching experiments were not excessive, and the investigations showed that serious consideration should be given to the feasibility of commercial production of high performance PAN-based carbon fibers by this processing route.     

Personality measures as predictors of smoking initiation and cessation in the UNC Alumni Heart Study.

MMPI data collected from a sample of college men and women during 1964–1967 were used to predict smoking initiation and cessation over a 20-yr follow-up period. People who subsequently began smoking were more rebellious, impulsive, sensation seeking, and hostile; were less likely to present a positive self-image; and were socially extraverted while in college. People who continued to smoke 20 yrs later were more hostile and sensation seeking. The personality variables that predicted smoking initiation and cessation were the same for men and women. Discussion centers on the potential role of hostility as a predictor of smoking cessation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Studies of transport critical currents and intergrain flux pinning in high-T c ceramic superconductors using persistent-mode rings

The measurements of the intergrain (Josephson) critical current and its dissipation were performed in granular superconductors of YBCO, YBCO/Ag (2 wt. %), and YBCO/Ag (4 wt. %). A self-sustaining supercurrent flowing in a superconducting ring and a contactless detection of its magnitude with a Hall probe were used in these studies. The results suggest that a small variation in the intergrain coupling energy is responsible for a weak Josephson flux pinning and a decay of the critical current.     

Atrial-Synchronized Demand Heart Pacing

A universal heart pacing method is proposed, making use of the atrial-synchronized and demand operation modes. The system includes an ECG-sensing network for control of the pacing action. Special logic design provides for processing the P- and QRS-waves in two parallel channels.     

Needed: Executive awareness of information resources

The authors argue that the development of international information markets requires a substantially heightened awareness on the part of executive decision makers of the characteristics of information and the potential of the information industry. They urge that the private and public sectors mount programs that will (1) educate executives in industry, government and academia on the value of scientific and technical information systems and services, (2) formulate strategies that view information and information systems as tradable commodities for national economic and diplomatic goals; and (3) develop marketing techniques for such commodities that take into account the social, economic and political environments of the clients. While these suggestions are aimed at the United States, they are believed to have an almost global relevance.     

A new approach to censored lifetime variables

A new statistical test with applications to censored lifetime data has been found. This test makes no assumptions about the dependence structure underlying the censoring. Here we describe the background to the test and give an algorithm to implement it. A number of numerical examples are given to illustrate how the algorithm may be applied.