AlGaAs/GaAs JFETs by organo-metallic and molecular beam epitaxy

Normally-off and normally-on AlGaAs/GaAs heterojunction gate GaAs FETs (HJFETs) for high-speed logic applications have been fabricated with molecular beam epitaxy (MBE) and organometallic vapour phase epitaxy (OM-VPE). The best normally-off devices used MBE n-GaAs active layers and OM-VPE gate layers of p+-AlGaAs and p+-GaAs. Saturation currents followed a square law and current scaling constants were the highest on record for HJFETs, greater than 50 ?A/?m-V2.     

Traumatic popliteal arteriovenous fistula. Diagnostic methods and surgical management

The popliteal vessels rank second only to the external iliac system as the most frequent site of acquired arteriovenous communication. Direct trauma to the popliteal space is by far the most common cause, and surgical intervention is usually required to manage the defect. We present a recent illustrative case following meniscectomy. To our knowledge, the occurrence of an arteriovenous fistula complicating knee surgery has not been reported previously. This case outlines the potential value of B-mode ultrasound in diagnosis and the use of intraoperative angiography in assessing the adequacy of primary vascular reconstruction. Earlier experience of this vascular abnormality--six additional cases since 1941--is reviewed.     

Construction Craft Workers’ Perceptions of the Factors Affecting Their Productivity

In efforts to quantify craft workers’ perspective of construction productivity, a nationwide survey involving 1,996 craft workers was employed. The survey quantified the relative impact of 83 productivity factors, which had been identified through a series of focus group sessions involving craft workers conducted on construction jobsites located throughout the United States. The findings show that craft workers do have a good understanding of the factors affecting their daily productivity, and most of the adversarial factors affecting productivity can be addressed by site management teams. Factors involving tools and consumables, materials, engineering drawing management and construction equipment were identified as having the greatest impact on productivity from the craft workers’ perspective. A statistical comparative analysis was employed to distinguish the significant factors encountered by craft workers on projects with relatively low perceived productivity. The research further examined the differences in the perceived relative magnitude of productivity factors’ influence on construction productivity based on respondents’ union status and trade. These findings will be beneficial for engaging craft workers in productivity improvement and improving the efficiency of construction jobsites.     

Epidermal growth factor and angiotensin II regulation of extracellular signal-regulated protein kinase in rat liver epithelial WB cells

Activation of extracellular signal-regulated protein kinase (ERK) is considered essential for mitogenesis. In the present study, rat liver epithelial WB cells were used to investigate the relative roles of Ca2+, protein kinase C (PKC), and protein tyrosine phosphorylation in mitogenesis and activation of the ERK pathway stimulated by epidermal growth factor (EGF) and angiotensin II (Ang II). The sensitivity of the ERK pathway to Ca2+ was studied by using 1,2-bis (O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) to chelate intracellular Ca2+ and a low extracellular Ca2+ concentration to prevent Ca2+ influx. Agonist-induced PKC activation was diminished by inhibition of PKC by GF-109203X (bisindolylmaleimide) or by down-regulation of PKC by long-term treatment of the cells with phorbol myristate acetate (PMA). Our results show that although activation of PKC was critical for mitogenesis induced by Ang II or EGF, the initial activation of ERK by both agonists in these cells was essentially independent of PKC activation and was insensitive to Ca2+ mobilization. This is in contrast to the findings in some cell types that exhibit a marked dependency on mobilization of Ca2+ and/or PKC activation. On the other hand, an obligatory tyrosine phosphorylation step for activation of ERK was indicated by the use of protein tyrosine kinase inhibitors, which profoundly inhibited the activation of ERK by EGF, Ang II, and PMA. Additional experiments indicated that tyrosine phosphorylation by a cytosolic tyrosine kinase may represent a general mechanism for G-protein coupled receptor mediated ERK activation.     

Multi-way versus one-way constraints in user interfaces: Experience with the deltablue algorithm

The efficient satisfaction of constraints is essential to the performance of constraint-based user interfaces. In the past, most constraint-based user interfaces have used one-way rather than multi-way constraints because of a widespread belief that one-way constraints were more efficient. In this paper we argue that many user interface construction problems are handled more naturally and elegantly by multi-way constraints than by one-way constraints. We present pseudocode for an incremental multi-way constraint satisfaction algorithm, DeltaBlue, and describe experience in using the algorithm in two user interface toolkits. Finally, we provide performance figures demonstrating that multi-way constraint solvers can be entirely competitive in performance with one-way constraint solvers.     

Visual search along the colour dimension.

Conducted 2 experiments in which 3 adults with normal or corrected-to-normal vision searched for a chromatic target among colored background items. Findings suggest that visual behavior as based on the operations of the preattentive visual system was either unaffected by factors (e.g., extent of target background similarity, background variance) that determined the level of complexity of a display or task or inhibited by their occurrence. In attention-based visual behavior, these factors exerted influence in a graded manner by modulating ease and speed with which the display was searched. Results support the heuristic value of the notion of A. Treisman (1985, 1986) of the availability of a feature map as a basis for determining the nature of a color search. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influenza A outbreak on a cruise ship

Data are presented from an investigation of the use of monophasic contraceptive pills chosen by different age groups. Analyses are made of the data obtained from the Bulgarian Association for Family Planning (BAFP) card index for the last two years. Information is given on the number of observed cycles, type of applied contraceptive pill, aims of their application (contraception, treatment of acne, menstrual disturbances etc.), age of patients, as well as any possible adverse effects--change in blood pressure, bodyweight changes, intermenstrual bleeding, hairiness, breast problems, paraclinical changes, etc. The observed cycles show a very small percentage of adverse effects with hormonal contraception, mainly during the first 2 or 3 cycles, with predominance of intermenstrual bleeding. No bodyweight changes or increased hairiness were observed.     

Electron dynamics in short-channel InP field-effect transistors

The transient response of electrons to a high field in InP has been calculated by a Monte Carlo method. The results are compared with previously published results for GaAs, and used to indicate the performance that may be obtained in InP and GaAs microwave f.e.t.s.     

Low-temperature air oxidation of caking coals. 2. Effect on swelling and softening properties

Three highly swelling bituminous coals (< 75 um > 63 um size) were pre-oxidized to various levels of weight gain and then their plastic properties monitored during carbonization. Additions of relatively small amounts of oxygen (<1–2% by wt) cause marked changes in swelling and softening properties. In general, oxidation causes: substantial reductions in volume changes, increases in softening and dilation temperatures, and a slight reduction in resolidification temperatures. For coals which exhibit high fluidities, slight oxidation results in an increase in expansion prior to destruction of swelling properties. For a given level of weight gain, reduction in plastic behaviour of a coal becomes more severe as the temperature of pre-oxidation is increased. Weathering studies indicate that exposure of an hvA bituminous coal to moist air at ambient temperature has more effect on subsequent swelling and softening properties than exposure to dry air. Fine coal particles stored for extended periods of time in atmospheres with even slight oxygen concentrations show definite signs of weathering. The plastic properties of an oxidized coal may be partially resotred by grinding to expose new surface.