Intracellular sequestration of sodium by a novel Na+/H+ exchanger in yeast is enhanced by mutations in the plasma membrane H+-ATPase. Insights into mechanisms of sodium tolerance

Sodium tolerance in yeast is disrupted by mutations in calcineurin, a Ca2+/calmodulin-dependent protein phosphatase, which is required for modulation of Na+ uptake and efflux mechanisms. Five Na+-tolerant mutants were isolated by selecting for suppressors of calcineurin mutations, and mapped to the PMA1 gene, encoding the plasma membrane H+-ATPase. One mutant, pma1-alpha4, which has the single amino acid change Glu367 --> Lys at a highly conserved site within the catalytic domain of the ATPase, was analyzed in detail to determine the mechanism of Na+ tolerance. After exposure to Na+ in the culture medium, 22Na influx in the pma1 mutant was reduced 2-fold relative to control, consistent with a similar decrease in ATPase activity. Efflux of 22Na from intact cells was relatively unchanged in the pma1 mutant. However, selective permeabilization of the plasma membrane revealed that mutant cells retained up to 80% of intracellular Na+ within a slowly exchanging pool. We show that NHX1, a novel gene homologous to the mammalian NHE family of Na+/H+ exchangers, is required for Na+ sequestration in yeast and contributes to the Na+-tolerant phenotype of pma1-alpha4.     

Predictors of user perceptions of web recommender systems: How the basis for generating experience and search product recommendations affects user responses

One critical question suggested by Web 2.0 is as follows: When is it better to leverage the knowledge of other users vs. rely on the product characteristic-based metrics for online product recommenders? Three recent and notable changes of recommender systems have been as follows: (1) a shift from characteristic-based recommendation algorithms to social-based recommendation algorithms; (2) an increase in the number of dimensions on which algorithms are based; and (3) availability of products that cannot be examined for quality before purchase. The combination of these elements is affecting users’ perceptions and attitudes regarding recommender systems and the products recommended by them, but the psychological effects of these trends remain unexplored. The current study empirically examines the effects of these elements, using a 2 (recommendation approach: content-based vs. collaborative-based, within)×2 (dimensions used to generate recommendations: 6 vs. 30, between)×2 (product type: experience products (fragrances) vs. search products (rugs), between) Web-based study (N=80). Participants were told that they would use two recommender systems distinguished by recommendation approach (in fact, the recommendations were identical). There were no substantive main effects, but all three variables exhibited two-way interactions, indicating that design strategies must be grounded in a multi-dimensional understanding of these variables. The implications of this research for the psychology and design of recommender systems are presented.     

Extending the Similarity‐Attraction Effect: The Effects of When‐Similarity in Computer‐Mediated Communication

The feeling of connectedness experienced in computer‐mediated relationships can be explained by the similarity‐attraction effect (SAE). Though SAE is well established in psychology, the effects of some types of similarity have not yet been explored. In 2 studies, we demonstrate similarity‐attraction based on the timing of activities—“when‐similarity.” We describe a novel experimental paradigm for manifesting when‐similarity while controlling for the activities being performed (what‐similarity). Study 1 (N = 24) shows when‐similarity attraction in the evaluation of connectedness with others. Study 2 (N = 42) identifies an interaction between who‐similarity—similarity in personal backgrounds—and when‐similarity. Both studies show that real‐time computer‐mediated interaction can lead to greater feelings of connectedness between people when there is an opportunity to discover when‐similarity.     

Schedule of Events

In this study, the effect of the user choice on social responses to computer-synthesized speech is investigated. Three previous findings about social responses to computer-synthesized speech (i.e., social identification, proximate source orientation, and similarity attraction) were tested using the choice paradigm. Social identification and proximate source orientation effects were found even when users had chosen a computer voice at their discretion. In addition, the primacy effect in the user choice prevailed: Participants were more likely to select whatever voice that they heard first between two options. The similarity attraction effect, however, was negated by the cognitive dissonance effect after user choices. The robustness of social responses, its implications for human–computer interaction, and the importance of the user choice in voice-interface designs are discussed.     

节省便携系统功率的设计思考

蜂窝电话是迅速发展的一个市场领域，预测明年可增长到２．５亿部；到２００３年可达５亿部。面对如此巨大的市场，制造商们尽全力使产品完备无缺，用某些关键指标使产品优于竞争对手。节省便携系统中每个部分的功率至关重要。例如，若ＣＰＵ功耗为４Ｗ，则降低２５％可节省１Ｗ，这对于由一对ＡＡ电池供电的手持装置意义尤其重大。设计人员千方百计节省可能节省的每一ｍＷ，如果使键盘控制器耗电从１０ｍＡ降到８ｍＡ，则可节省６．６ｍＷ（使用３．３Ｖ电源）。在蜂窝电话和计算机中能节省功率的产品是大不相同的，尽管它们的目的都是延长…     

电子图书设计初探

高技术让我们生活得更舒适.所有这些新技术发明是对有用的老式技术的改进.以PDA为例,我个人认为,它的确超越了过时的记事簿.     

分立逻辑器件何去何从

分立逻辑功能合并的趋势随处可见，很久以前就出现了芯片组，而且这一技术还在发展。一般说来，设计师想极力摆脱分立逻辑，但历史经验告诉我们，人们将不可能完全摒弃逻辑器件。市场调研表明：前年，逻辑产品的全部有效市场额度（TAM）为24亿美元。如果按工艺技术划分的话，CMOS逻辑占18.7亿美元，其次是BiCMOS，为3.05亿美元，而TTL（包括最早的双极工艺）为3.09亿美元。有朝一日会实现集成化确实，只要有可能，分立逻辑功能已被并入在其它器件中，如母板上的芯片组中。但对某些功能，还是需要分立逻辑。一个重要原因是，随着速度和…     

The development of drawing in children with congenital focal brain injury: evidence for limited functional recovery

Children with pre- or perinatal injury to right hemisphere (RH) brain regions show impairment of spatial integrative functions similar to that observed among adults with comparable injury. Unlike adults, children show considerable improvement with development on a range of spatial construction tasks which require spatial integration. Such gains could reflect true recovery of spatial integrative abilities. Alternatively, the improvement could be more limited in scope, reflecting the development of compensatory strategies which are task specific and allow the children to circumvent, rather than overcome, their primary spatial disorders. The studies presented here examined this distinction within the context of drawing tasks in which the child was first asked to draw a house and then an impossible house. The impossible house task was designed to examine the extent to which children rely on graphic formulas in generating organized drawings. The results showed that while all of the children with RH injury make considerable progress in free drawing into the school age period, they are very reliant on the use of graphic formulas. When given a task which requires them to alter their drawings, they did not change the spatial configuration of the depicted object. Rather they found alternate ways to render the object 'impossible'.     

Conduction aphasia in a 3-year-old with a left posterior cortical/subcortical abscess

A 3-year-old, right-handed girl developed a conduction-type aphasia following a second generalized seizure in the setting of a developing abscess involving left subcortical and cortical angular gyrus and arcuate fasciculus, and the posterior corpus callosum. The language disorder was fluent, characterized by age appropriate mean length of utterance and syntax, but with markedly reduced spontaneity of output, rapid rate of speech and mild dysarthria. Comprehension was relatively, but not completely spared. Naming, repetition, and reading (letters) were initially markedly impaired. Improvements in naming and repetition were associated with both literal and semantic paraphasias. Writing skills in the form of drawing were spared, but a mild apraxia to verbal command and imitation was initially present. Despite her young age, this child's fluent conduction aphasia and lesion localization were adult-like. Multimodal memory difficulties appeared to underlie what is best described as conduction aphasia.