Usability in computer documentation design: conceptual andmethodological considerations

The multidimensional nature of usability (including tradeoffs between dimensions) is described, stressing the linkage of the concept to the effective use of documentation by a particular group of readers in performing a certain set of software-related tasks under realistic environmental constraints. Major issues in the evaluation and design of usability are examined. It is argued that the sampling of realistic tasks and target readers is often very difficult, particularly in a laboratory setting, and that additional emphasis must be placed on using multiple observation periods, standardized measures and materials, and multimethod assessments of usability     

Probing charge transfer at surfaces using graphene transistors

Graphene field effect transistors (FETs) are extremely sensitive to gas exposure. Charge transfer doping of graphene FETs by atmospheric gas is ubiquitous but not yet understood. We have used graphene FETs to probe minute changes in electrochemical potential during high-purity gas exposure experiments. Our study shows quantitatively that electrochemistry involving adsorbed water, graphene, and the substrate is responsible for doping. We not only identify the water/oxygen redox couple as the underlying mechanism but also capture the kinetics of this reaction. The graphene FET is highlighted here as an extremely sensitive potentiometer for probing electrochemical reactions at interfaces, arising from the unique density of states of graphene. This work establishes a fundamental basis on which new electrochemical nanoprobes and gas sensors can be developed with graphene.     

汽车保护系统中的分布式架构

如今的汽车制造商正积极努力减轻整车的重量，从而有助于降低二氧化碳（CO2）的排放量．提高燃料的利用效率。设计工程师们正在努力开发新的技术和设计技巧．在不牺牲系统可靠性的前提下．降低汽车中线束的重量。正在涌现的线材技术是一项可以使重量大幅降低的技术，这种技术可以以更小的线径实现更大的电流承载量。如今．汽车研发工程师们正在重新采用众所周知的成熟技术．     

运用PolySwitch PPTC器件的分散式架构进行汽车线束保护的优势

简介 为了降低二氧化碳排放水平、提高燃料能效汽车制造企业如今正在朝着车辆减重这一方向积极努力.因此设计师们也在不断寻求能帮助他们有效减轻线束重量的新技术和设计手段.为了保持市场竞争力,汽车制造商还必须降低保修成本并改善用户满意度.所以,汽车设计师们正面临着寻找一条新出路的挑战一既要减轻车重,又不能牺牲系统可靠性.     

Characterization of AT4 receptor from bovine aortic endothelium with photosensitive analogues of angiotensin IV

Newly developed photosensitive analogues of AngIV were used to characterize the AT4 receptor of bovine aortic endothelial cells. The photoactivatable AngIV analogues [N3-Phe6]AngIV and [Bpa6]AngIV displayed high affinities for AT4 receptor, with IC50's of 3.7 +/- 0.3 and 19.1 +/- 3.5 nM, respectively. The radioiodinated ligands showed a good efficiency of photoaffinity labeling demonstrated by high proportions (60-75%) of acid-resistant binding. Covalently labeled receptor was solubilized under reducing or nonreducing conditions and subjected to SDS-PAGE. Under nonreducing conditions, autoradiographies revealed a major band of Mr 186 +/- 2 kDa and a minor band of Mr 241 +/- 6 kDa. The labeling of these bands was completely abolished in the presence of 10 microM AngIV. Under reducing conditions, only the low Mr 186 kDa band was revealed. After endoglycosidase digestion with an enzyme that cleaves N-linked saccharides, the Mr of the denatured AT4 receptor was decreased by 31% to a value of 129 +/- 10 kDa. Kinetic studies revealed a stepwise process of AT4 receptor deglycosylation by endoglycosidase F, suggesting at least two different sites of N-linked saccharides. Mild trypsin treatment of photolabeled endothelial cell membranes released a large fragment of Mr 177 +/- 3 kDa which accounts for about 95% of the whole receptor molecular mass. These results demonstrate that [N3-Phe6]AngIV and [Bpa6]AngIV are very efficient tools for selective photoaffinity labeling of AT4 receptor. We have shown that AT4 receptor is a 186 kDa integral membrane glycoprotein with a very large extracellular domain. These properties are consistent with those of a growth factor or cytokine receptor.     

Chemical vapor deposition synthesis of graphene on copper with methanol, ethanol, and propanol precursors

Large area, high quality graphene was synthesized from different liquid alcohols by chemical vapor deposition on copper foils in a tube furnace. The quality of the synthesized graphene was systematically investigated with various growth conditions. Alcohol vapor exposure times of 5 min and an average growth temperature of 850 °C yield continuous graphene monolayer films, as inferred from Raman spectroscopy. X-ray photoelectron spectroscopy shows that the oxygen moieties found in the source molecules have no measureable doping or oxidation effect in the synthesized graphene. Raman spectroscopy indicates that graphene films transferred to insulating substrates are of high quality. The field effect mobility of large area graphene transistors was measured at room temperature to be in the range 1800–2100 cm²/V s at carrier densities between 10¹¹/cm² and 10¹²/cm².     

The high affinity state of inositol 1,4,5-trisphosphate receptor is a functional state

Inositol 1,4,5-trisphosphate (InsP3) is a second messenger responsible for the rapid and discontinuous release of Ca2+ from intracellular stores. In this study, the effects of the sulfhydryl reagent thimerosal were investigated on Ca2+ mobilization and on InsP3 binding. Thimerosal was shown to release Ca2+, in a dose-dependent manner, with an EC50 of 135.8 +/- 5.2 microM, from bovine adrenal cortex microsomes. Thimerosal-induced Ca2+ release was not prevented by heparin (250 micrograms/ml), ruling out a participation of InsP3 receptor in that effect. The slow rate of thimerosal-induced Ca2+ release rather suggested an inhibition of microsomal Ca2+ ATPase. At submaximal concentration, thimerosal (100 microM) was also shown to potentiate the release of Ca2+ induced by InsP3. Dose-response experiments revealed that thimerosal enhanced the apparent affinity of InsP3 by a factor 2.21 +/- 0.28, without modifying the maximal amount of Ca2+ released by InsP3. Thimerosal also enhanced, in a dose-dependent manner, [3H]InsP3 binding to adrenal cortex microsomes (EC50 = 43.3 +/- 7.6 microM). A similar effect was also observed on [3H]InsP3 binding to solubilized receptors, suggesting a direct modification of the receptor protein by thimerosal. The effects of thimerosal on Ca2+ release and [3H]InsP3 binding were abolished in the presence of the reducing agent dithiothreitol (1 mM), suggesting a modification by thimerosal of specific thiol groups on these microsomal proteins. Scatchard analysis revealed that thimerosal (100 microM) increased InsP3 receptor affinity by 1.87 +/- 0.26-fold. Kinetic analysis indicated that this increased affinity was due to an enhancement of InsP3 association rate constant. The concomitant increases of binding affinity and Ca2+ releasing potency suggest that the high affinity state of InsP3 receptor is a functional state.     

Bovine adrenal glomerulosa cells express such a low level of functional B2 receptors that bradykinin does not significantly increase their aldosterone production

The transverse tubule system of the cardiomyocyte remains undeformed despite the extreme forces it undergoes during the contraction-relaxation cycle, but the morphological basis for its stability remains unclear. Therefore, we have investigated the architecture and subcellular protein scaffold of the cardiac T-tubules and compared it with that of the costameres and of the free sarcolemma. Tissue samples from normal rat and monkey hearts, and left ventricular tissue from normal and cardiomyopathic human hearts obtained at transplantation surgery were investigated using immunocytochemistry and confocal microscopy and by electron microscopy. In addition, we used a re-differentiation model of isolated, cultured adult rat cardiomyocytes. The cell membrane of the cardiac T-tubules was found to contain the cell-matrix focal adhesion molecules (FAMs) vinculin, talin, the alpha5beta1 integrin and the membrane-associated proteins (MAPs) dystrophin and spectrin. FAMs and MAPs were localized in the T-tubular membrane in a similar pattern: in longitudinally oriented myocytes as transverse punctate lines at the Z-level; in transversally cut myocytes a radial tubular network was found to extend throughout the interior of the cell. Immunolabeling for basement membrane components including collagen IV, fibronectin and laminin showed a colocalization with FAMs and MAPs parallel to the transverse T-tubules. The costameres of the sarcolemma showed a protein composition resembling that of the T-tubules but the intervening segments of free sarcolemma showed absence of FAMs and presence of MAPs. For the first time, we demonstrate the existence and protein composition of the T-tubular scaffold in the human heart. Furthermore, we show that cardiomyocytes from human failing hearts have less abundant but more dilated T-tubules than do experimental animals. These results indicate that the cardiac T-tubular system contains a subcellular scaffold closely resembling that of the costameres. It consists of FAMs, MAPs and basal lamina proteins that confer structural integrity to the cardiac T-tubular membrane during contraction/relaxation cycles.     

Defining decision making process performance: Conceptualization and validation of an index

Many studies have demonstrated the impact of information technology (IT) on decision making but few have used decision making process performance (DMPP) as a dependent variable. Our study proposes a rich formative conceptualization of DMPP, a valid and reliable measure for this construct, and studies its influence on the quality of decision making. The results show that DMPP is a formative second-order aggregate construct composed of procedural rationality, exhaustivity of the information analyzed, openness of spirit, and effort. This study illustrates the importance of building proper definitions of constructs and contributes to the development of shared meaning in IS.