bluuebunny/crossref_metadata_2025 huggingface dataset:
UNDERSTANDING THE DETERMINANTS OF EMPLOYER USE OF SELECTION METHODS
Authors: WILK STEFFANIE L. , CAPPELLI PETER
Published: December 2006

This study uses national probability data from over 3,000 employers to examine why employers differ in their use of employee selection methods. Although the research on employee selection is voluminous, there have been only a handful of studies that look at the employers' selection decisions. In contrast to those other studies, we focus on characteristics of work as predictors of firms' decisions regarding selection practices. Beyond the relationship to the overall extent of selection methods used, we argue that specific work characteristics will affect the use of specific types of selection methods. We find, for example, that the greater the skill requirements of a position, the more likely that the establishment will use those types of selection methods that tap into the ability and skills of the applicants, namely, academic achievement and test performance. Discussion and suggestions for future research are offered.
A META‐ANALYSIS OF THE CRITERION‐RELATED VALIDITY OF ASSESSMENT CENTER DIMENSIONS
Authors: ARTHUR WINFRED , DAY ERIC ANTHONY , MCNELLY THERESA L. , EDENS PAMELA S.
Published: December 2006

We used meta‐analytic procedures to investigate the criterion‐related validity of assessment center dimension ratings. By focusing on dimension‐level information, we were able to assess the extent to which specific constructs account for the criterion‐related validity of assessment centers. From a total of 34 articles that reported dimension‐level validities, we collapsed 168 assessment center dimension labels into an overriding set of 6 dimensions: (a) consideration/awareness of others, (b) communication, (c) drive, (d) influencing others, (e) organizing and planning, and (f) problem solving. Based on this set of 6 dimensions, we extracted 258 independent data points. Results showed a range of estimated true criterion‐related validities from .25 to .39. A regression‐based composite consisting of 4 out of the 6 dimensions accounted for the criterion‐related validity of assessment center ratings and explained more variance in performance (20%) than Gaugler, Rosenthal, Thornton, and Bentson (1987) were able to explain using the overall assessment center rating (14%).
THE CORE SELF‐EVALUATIONS SCALE: DEVELOPMENT OF A MEASURE
Authors: JUDGE TIMOTHY A. , EREZ AMIR , BONO JOYCE E. , THORESEN CARL J.
Published: December 2006

Despite an emerging body of research on a personality trait termed core self‐evaluations, the trait continues to be measured indirectly. The present study reported the results of a series of studies that developed and tested the validity of the Core Self‐Evaluations Scale (CSES), a direct and relatively brief measure of the trait. Results indicated that the 12‐item CSES was reliable, displayed a unitary factor structure, correlated significantly with job satisfaction, job performance, and life satisfaction, and had validity equal to that of an optimal weighting of the 4 specific core traits (self‐esteem, generalized self‐efficacy, neuroti‐cism, and locus of control), and incremental validity over the 5‐factor model. Overall, results suggest that the CSES is a valid measure that should prove useful in applied psychology research.
INTEGRATING ERRORS INTO THE TRAINING PROCESS: THE FUNCTION OF ERROR MANAGEMENT INSTRUCTIONS AND THE ROLE OF GOAL ORIENTATION
Authors: HEIMBECK DOERTE , FRESE MICHAEL , SONNENTAG SABINE , KEITH NINA
Published: December 2006

Error management training explicitly allows participants to make errors. We examined the effects of error management instructions (“rules of thumb” designed to reduce the negative emotional effects of errors), goal orientation (learning goal, prove goal, and avoidance goal orientations) and attribute x treatment interactions on performance. A randomized experiment with 87 participants consisting of 3 training procedures for learning to work with a computer program was conducted: (a) error training with error management instructions, (b) error training without error management instructions; and (c) a group that was prevented from making errors. Results showed that short‐and medium‐term performance (near and far transfer) was superior for participants of the error training that included error management instructions, compared with the two other training conditions. Thus, error management instructions were crucial for the high performance effects of error training. Prove and avoidance goal orientation interacted with training conditions.
LEARNING WITHIN A LEARNER CONTROL TRAINING ENVIRONMENT: THE INTERACTIVE EFFECTS OF GOAL ORIENTATION AND METACOGNITIVE INSTRUCTION ON LEARNING OUTCOMES
Authors: SCHMIDT AARON M. , FORD J. KEVIN
Published: December 2006

This study proposes that effective engagement in metacognitive activities is critical to success in high learner‐control training environments. A model was developed that focuses on the interactive effects of goal orientation and a metacognitive training intervention on metacognitive activity and learning outcomes. Seventy‐nine participants completed a Web‐based training course on how to create Web pages. Consistent with expectations, learners reporting greater levels of metacognitive activity during training gained more declarative knowledge, performed better on a skill‐based measure, and had higher levels of self‐efficacy. Metacognitive activity was also found to partially mediate the relationship between goal orientation and learning outcomes. Finally, the expected goal orientation by intervention interaction was found. The metacognitive intervention was beneficial in enhancing metacognitive activity for trainees with low performance‐avoidance orientations, but resulted in lower metacognitive activity among highly avoidant learners. Implications of these findings for research on self‐regulation and training practice are discussed.
THE EFFECTS OF PHYSICAL ATTRACTIVENESS ON JOB‐RELATED OUTCOMES: A META‐ANALYSIS OF EXPERIMENTAL STUDIES
Authors: HOSODA MEGUMI , STONE‐ROMERO EUGENE F. , COATS GWEN
Published: December 2006

We report the findings of a meta‐analytic review of experimental studies concerned with the biasing effect of physical attractiveness on a variety of job‐related outcomes. In support of implicit personality theory, attractive individuals were found to fare better than unattractive individuals in terms of a number of such outcomes. The weighted mean effect size, d, was .37 for all studies. In addition, tests for moderating effects showed that (a) the attractiveness bias did not differ between studies that provided low versus high amounts of job‐relevant information about the targets, (b) the same bias was greater for within‐subjects research designs than for between‐subjects designs, (c) professionals were as susceptible to the bias as were college students, (d) attractiveness was as important for men as for women, and (e) the biasing effect of attractiveness has decreased in recent years. Implications of these findings are considered.
LINKING O*NET JOB ANALYSIS INFORMATION TO JOB REQUIREMENT PREDICTORS: AN O*NET APPLICATION
Authors: JEANNERET P. RICHARD , STRONG MARK H.
Published: December 2006

This is an exploratory study that examined the possible application of the job component validity (JCV) model to identify potential employee selection instruments and to determine job requirement levels from O*NET job analysis data, following a research paradigm established with the Position Analysis Questionnaire (PAQ). Job requirements were measured by mean aptitude test scores on the General Aptitude Test Battery (GATB), and the ratings on the O*NET Generalized Work Activities (GWAs) were selected as representative O*NET job analysis data. Multiple correlation coefficients ranging from .35 to .89 were found when predicting mean GATB test scores from GWAs. Similar to JCV research some 30 years ago, predictions were strongest for cognitive aptitudes and weakest for manual dexterity. The data were examined under both rational and cross‐validated empirical models. The results have positive implications for the development of a database that would support JCV estimates derived from O*NET job analysis data and allow practitioners to use O*NET data to help identify useful employee selection instruments.
EMPLOYEES THAT THINK AND ACT LIKE OWNERS: EFFECTS OF OWNERSHIP BELIEFS AND BEHAVIORS ON ORGANIZATIONAL EFFECTIVENESS
Authors: WAGNER STEPHEN H. , PARKER CHRISTOPHER P. , CHRISTIANSEN NEIL D.
Published: December 2006

A model of the psychological experience of employee ownership in work groups was developed to investigate antecedents (participation in a 401 (k) program and a climate of self‐determination) and consequences (employee attitudes and financial performance) of psychological ownership. Based on data from a large retail organization, results showed that working in a climate supporting self‐determination and 401(k) participation were positively related to the level of ownership beliefs in the 204 work groups studied. Ownership beliefs were positively related to ownership behaviors and employees' attitudes toward the organization, whereas ownership behaviors were positively related to financial performance. Implications of psychological ownership for organizational behavior and performance are discussed.
REPORTED INCIDENCE RATES OF WORK‐RELATED SEXUAL HARASSMENT IN THE UNITED STATES: USING META‐ANALYSIS TO EXPLAIN REPORTED RATE DISPARITIES
Authors: ILIES REMUS , HAUSERMAN NANCY , SCHWOCHAU SUSAN , STIBAL JOHN
Published: December 2006

This study presents a meta‐analytic review of the incidence of sexual harassment in the U.S. The impact of 3 main moderator variables (type of survey used, sampling technique, and the type of work environment in which the study was conducted) on the reported incidence rate was estimated by cumulating incidence rates reported in the literature. Results show that directly querying the respondents about whether or not they experienced sexual harassment (vs. using questionnaires that listed behaviors believed to constitute sexual harassment), and employing probability‐sampling techniques (vs. convenience sampling), led to substantially lower estimates of sexual harassment incidence. In addition, the results suggest that sexual harassment is more prevalent in organizations characterized by relatively large power differentials between organizational levels. Based on more than 86,000 respondents from 55 probability samples, on average, 58% of women report having experienced potentially harassing behaviors and 24% report having experienced sexual harassment at work.
TIME MATTERS IN TEAM PERFORMANCE: EFFECTS OF MEMBER FAMILIARITY, ENTRAINMENT, AND TASK DISCONTINUITY ON SPEED AND QUALITY
Authors: HARRISON DAVID A. , MOHAMMED SUSAN , MCGRATH JOSEPH E. , FLOREY ANNA T. , VANDERSTOEP SCOTT W.
Published: December 2006

We compared the speed and quality of performance for familiar, initially unfamiliar but continuing, and one‐shot (single session) teams. We also proposed and observed entrainment effects for task time limits. Over the course of weekly sessions with changing tasks, continuing teams reached speed levels of the initially familiar teams, but the one‐shot teams were consistently slower. Continuing teams also tended to have higher‐quality output than the one‐shot teams. There were no differences in how quickly each type of group entrained to time limits on the tasks. Entrainment was not robust to task discontinuity (Task A, then B). However, entrainment on repeated trials of a task persisted even when a different type of task “interrupted” those repeated trials (Task A, then B, then A again). Results compel a richer incorporation of time as a medium for complex task sequences, and time‐based constructs as a feature of team membership in the study of group effectiveness.
ACTION TRAINING FOR CHARISMATIC LEADERSHIP: TWO EVALUATIONS OF STUDIES OF A COMMERCIAL TRAINING MODULE ON INSPIRATIONAL COMMUNICATION OF A VISION
Authors: FRESE MICHAEL , BEIMEL SUSANNE , SCHOENBORN SANDRA
Published: December 2006

An action training program that teaches inspirational communication of a vision as part of a training of charismatic leadership for managers is presented (1½ days) and evaluated in 2 studies (N= 25 and N= 22). We used the research design “nonequivalent dependent variable design” (Cook & Campbell, 1979, p, 118) or “internal referencing strategy” (Haccoun & Hamtieux, 1994), which compared the trained behaviors (charismatic inspirational communication) with behaviors that were not trained (public speech) to control for testing and Hawthorne effects. The training had specific positive effects on those behaviors that were trained but not on those variables that were not trained. Good to excellent effect sizes appeared as a result of the training. We suggest that this research design is useful for evaluation of training effects within the constraints of commercial settings and, moreover, we argue that this design is in many ways superior to a nonequivalent nontraining control group design because it controls for testing effects and for effects that otherwise would need a pseudo‐training control group.
INVESTMENT IN WORK AND FAMILY ROLES: A TEST OF IDENTITY AND UTILITARIAN MOTIVES
Authors: ROTHBARD NANCY P. , EDWARDS JEFFREY R.
Published: December 2006

This study compared identity and utilitarian motives as predictors of time investment in work and family roles, using structural equation modeling with a sample of 623 working men and women. We tested within‐role and cross‐role relationships as well as the reciprocal effects of time invested in one role on time invested in the other role. As predicted, identification with a role was positively related to time invested in that role. However, findings for role utility were more complex. Time investment was positively related to both the pleasure and displeasure associated with a role. These findings suggest that people not only seek pleasure from roles but also invest time coping with role displeasure. The cross‐role findings supported resource drain and accommodation but not compensation as explanations of work‐family linking mechanisms. Gender analyses suggested that, for men, increased work time investment reduced time devoted to family, but increased family time investment did not affect time devoted to work. However, for women, increased time investment in either work or family reduced time devoted to the other role. These findings suggest that men may have greater reserves of time from roles other than work and family that make it unnecessary for them to draw from work time to meet increased family demands.
WEB‐BASED AND PAPER‐AND‐PENCIL TESTING OF APPLICANTS IN A PROCTORED SETTING: ARE PERSONALITY, BIODATA, AND SITUATIONAL JUDGMENT TESTS COMPARABLE?
Authors: PLOYHART ROBERT E. , WEEKLEY JEFF A. , HOLTZ BRIAN C. , KEMP CARY
Published: December 2006

This quasi‐experimental study compares the equivalence of proctored Web‐based tests to paper‐and‐pencil tests in a selection setting. The predictor battery was composed of measures of Conscientiousness, Agreeableness, Emotional Stability, a biodata form, and a situational judgment test. Three samples were administered the same test items, but differed with respect to context and test format: 425 incumbents completed a paper‐and‐pencil version, 2,544 applicants completed a paper‐and‐pencil version, and 2,356 applicants completed an identical Web‐based version (although these individuals were not randomly assigned to test format, the job and organization were the same for all samples). The results found effects for both context and test format. Relative to the applicants completing the paper‐and‐pencil measures, the Web‐based measures showed (a) better distributional properties, (b) lower means, (c) more variance, (d) higher internal consistency reliabilities, and (e) stronger intercorrelations. Although the applicant context resulted in higher mean responses than the incumbent context, this difference was about twice as large for the paper‐and‐pencil test than for the Web‐based test. All such differences were greater for personality measures than for biodata and situational judgment tests. Overall, these results suggest that proctored Web‐based testing has some positive benefits relative to paper‐and‐pencil measures, and we identify several implications of these findings for research and practice.
“We want no teachers who say there are two sides to every question”: Conservative Women and Education in the 1930s
Authors: Erickson Christine K.
Published: December 2006

Refuse to allow your children to be taught by radical teachers. In some places that may mean teaching them at home. Well, then, teach them at home! No matter if it is the fashionable thing in your town to send girls to one of the colleges dominated by socialists—refuse to send your daughter—better for her to be without an A.B. than to be a disloyal citizen.
The Medicalization of Education: A Historiographic Synthesis
Authors: Petrina Stephen
Published: December 2006

We believed we had overwhelming evidence that to know a child better is to love it more.
Moving Up the Ranks: Chiefly Status, Prestige, and Schooling in Colonial Fiji
Authors: White Carmen M.
Published: December 2006

In a 1987 volume titledClass and Culture in the South Pacific, Samoan historian Malama Meleisea describes orthodox Marxism, modernization theory, and unilineal evolutionary thought as united in their “Eurocentric frame of reference,” their “notion of unilineal progress,… assumption that pre-capitalist social institutions are obsolete and that class formation is historically inevitable.” While Meleisea's pointed polemic against metanarratives that privilege a universality of Western laws of historical development and progress is partly informed by the undelivered promises of modernization theory, his critique is more than the mere stirrings of an incipient postmodernist discourse. It also derives from a practical engagement with socio-political developments in the South Pacific region that puts in relief the ways in which grand paradigms can mold and distort contemporary Pacific Island institutions into Western images. Here, he speaks to the tendency to explain the endurance of chieftaincies in modern Pacific states as homologous with, a local variant, or the actual equivalent of, a new type of “class relations.” In a more recent edited volume that focuses on chiefs in the contemporary Pacific, White and Lindstrom similarly note a popular regard for chiefs as “antique survivals from pre-state political formations” that ultimately fails to address contemporary chiefly authority on its own terms. As White and Lindstrom note further, based on the projections of development proposed in Weber-inspired modernization theory, chiefs should have become obsolete in the modern nation-state: “The forces of modernity were meant to usher him (or sometimes her) from the global stage, replacing tribal or feudal styles of leadership wkh thg universalistic, rational forms of the natioh-state and its attendant bureaucracies.”
Preload maintenance and the left ventricular response to prolonged exercise in men
Authors: Dawson E. A. , Shave R. , Whyte G. , Ball D. , Selmer C. , Jans Ø. , Secher N. H. , George K. P.
Published: December 2006

This study examined whether left ventricular function was reduced during 3 h of semi‐recumbent ergometer cycling at 70% of maximal oxygen uptake while preload to the heart was maintained via saline infusion. Indices of left ventricular systolic function (end‐systolic blood pressure–volume relationship, SBP/ESV) and diastolic filling (ratio of early to late peak filling velocities into the left ventricle, E:A) were calculated during recovery and compared with baseline resting data. During exercise in seven healthy, trained male subjects, an arterial catheter allowed continuous assessment of arterial pressure, stroke volume (SV), cardiac output (
) and an index of contractility (dP/dtmax). A venous catheter assessed that central venous pressure (CVP) was maintained throughout rest, exercise and 10 min into recovery. Both systolic blood pressure and heart rate (HR) increased with the onset of exercise (from 132 ± 5 to 185 ± 19 mmHg and from 66 ± 9 to 135 ± 23 beats min−1; increases from rest to the end of the first 5 min of exercise in SBP and HR, respectively) but systolic blood pressure did not change from 30 to 180 min of exercise (∼150 mmHg), while heart rate only increased by 8 ± 9 beats min−1 (means ±s.d.; P > 0.05). The attenuated increase in HR compared with other studies suggests that the maintained CVP (∼5 mmHg) helped to prevent cardiovascular drift in this protocol. Stroke volume,
and dP/dtmax were all increased with the onset of exercise (from 85 ± 8 to 120 ± 18 ml, from 5.4 ± 1.3 to 16.5 ± 3.3 l min−1 and from 14.4 ± 4 to 28 ± 8 mmHg s−1; values from rest to the end of the first 5 min of exercise for SV,
and dP/dtmax, respectively) and were maintained during exercise. There was no difference in the SBP/ESV ratio from pre‐ to postexercise. Conversely, E:A was reduced from 2.0 ± 0.4 to 1.6 ± 0.5 postexercise (P < 0.05), returning to normal values at 24 h postexercise. This change in diastolic filling could not be fully explained (r2= 0.39) by an increased heart rate and, with CVP unchanged, it is likely to represent some depression of intrinsic relaxation properties of left ventricular myocytes. Three hours of semi‐supine cycling resulted in no evidence of a depression in left ventricular systolic function, while left ventricular diastolic function declined postexercise.
Fibre type distribution and gene expression levels of both succinate dehydrogenase and peroxisome proliferator‐activated receptor‐γ coactivator‐1α of fibres in the soleus muscle of Zucker diabetic fatty rats
Authors: Adachi Tetsuya , Kikuchi Naoko , Yasuda Koichiro , Anahara Reiko , Gu Ning , Matsunaga Tetsuro , Yamamura Tsubasa , Mori Chisato , Tsujimoto Gozoh , Tsuda Kinsuke , Ishihara Akihiko
Published: December 2006

We have reported that a change in muscle fibre type distribution is present in two strains of diabetic rats (Otsuka Long–Evans Tokushima Fatty and Goto‐Kakizaki rats). In this study, we determined whether the change in soleus muscle fibre type distribution was caused by diabetes, using obese, diabetic (Zucker diabetic fatty, ZDF), obese, non‐diabetic (Zucker fatty, ZF) and non‐diabetic, non‐obese rats (Zucker lean, ZL). Moreover, we investigated whether the gene expression levels of metabolic key molecules, namely the transcriptional factors of metabolic genes, exemplified by peroxisome proliferator‐activated receptor‐γ coactivator‐1α (PGC‐1α), and the oxidative enzymes in mitochondria, exemplified by succinate dehydrogenase (SDH), were changed in type I and II muscle fibres in each type of rat, using the new technique of laser capture microdissection (LCM). Both plasma glucose and glucosylated haemoglobin levels were significantly higher in ZDF than in ZL and ZF rats. A lower percentage of type IIA fibres was observed in the muscles of ZDF rats than in those of ZL and ZF rats. The mRNA expression levels of SDH in type II fibres and of PGC‐1α in type I fibres were significantly lower in ZDF than in ZL and ZF rats as assessed by LCM and real‐time PCR analysis. We have shown, for the first time, that a lower percentage of type IIA fibres was observed in ZDF rats. We have also discovered that the expression levels of the oxidative metabolism‐related genes, PGC‐1α and SDH, decreased in type I and type II fibres, respectively, of ZDF rats.
Glucose sensing by hypothalamic neurones and pancreatic islet cells: AMPle evidence for common mechanisms?
Authors: Mountjoy Philip D. , Rutter Guy A.
Published: December 2006

A fuller understanding of the central mechanisms involved in controlling food intake and metabolism is likely to be crucial for developing treatments to combat the growing problem of obesity in Westernised societies. Within the hypothalamus, specialized neurones respond to both appetite‐regulating hormones and circulating metabolites to regulate feeding behaviour accordingly. Thus, the activity of hypothalamic glucose‐excited and glucose‐inhibited neurones is increased or decreased, respectively, by an increase in local glucose concentration. These ‘glucose‐sensing’ neurones may therefore play a key role in the central regulation of food intake and potentially in the regulation of blood glucose concentrations. Whilst the intracellular signalling mechanisms through which glucose‐sensing neurones detect changes in the concentration of the sugar have been investigated quite extensively, many elements remain poorly understood. Furthermore, the similarities, or otherwise, with other nutrient‐sensing cells, including pancreatic islet cells, are not completely resolved. In this review, we discuss recent advances in this field and explore the potential involvement of AMP‐activated protein kinase and other nutrient‐regulated protein kinases.
The functional nature of synaptic circuitry is altered in area CA3 of the hippocampus in a mouse model of Down's syndrome
Authors: Hanson Jesse E. , Blank Martina , Valenzuela Ricardo A. , Garner Craig C. , Madison Daniel V.
Published: December 2006

Down's syndrome (DS) is the most common cause of mental retardation, and memory impairments are more severe in DS than in most if not all other causes of mental retardation. The Ts65Dn mouse, a genetic model of DS, exhibits phenotypes of DS, including memory impairments indicative of hippocampal dysfunction. We examined functional synaptic connectivity in area CA3 of the hippocampus of Ts65Dn mice using organotypic slice cultures as a model. We found reductions in multiple measures of synaptic function in both excitatory and inhibitory inputs to pyramidal neurons in CA3 of the Ts65Dn hippocampus. However, associational synaptic connections between pyramidal neurons were more abundant and more likely to be active rather than silent in the Ts65Dn hippocampus. Synaptic potentiation was normal in these associational connections. Decreased overall functional synaptic input onto pyramidal neurons expressed along with the specific hyperconnectivity of associational connections between pyramidal neurons will result in predictable alterations of CA3 network function, which may contribute to the memory impairments seen in DS.
Long‐chain omega‐3 fatty acids regulate bovine whole‐body protein metabolism by promoting muscle insulin signalling to the Akt–mTOR–S6K1 pathway and insulin sensitivity
Authors: Gingras Andrée‐Anne , White Phillip James , Chouinard P. Yvan , Julien Pierre , Davis Teresa A. , Dombrowski Luce , Couture Yvon , Dubreuil Pascal , Myre Alexandre , Bergeron Karen , Marette André , Thivierge M. Carole
Published: December 2006

The ability of the skeletal musculature to use amino acids to build or renew constitutive proteins is gradually lost with age and this is partly due to a decline in skeletal muscle insulin sensitivity. Since long‐chain omega‐3 polyunsaturated fatty acids (LCn–3PUFA) from fish oil are known to improve insulin‐mediated glucose metabolism in insulin‐resistant states, their potential role in regulating insulin‐mediated protein metabolism was investigated in this study. Experimental data are based on a switchback design composed of three 5 week experimental periods using six growing steers to compare the effect of a continuous abomasal infusion of LCn–3PUFA‐rich menhaden oil with an iso‐energetic control oil mixture. Clamp and insulin signalling observations were combined with additional data from a second cohort of six steers. We found that enteral LCn–3PUFA potentiate insulin action by increasing the insulin‐stimulated whole‐body disposal of amino acids from 152 to 308 μmol kg−1 h−1 (P= 0.006). The study further showed that in the fed steady‐state, chronic adaptation to LCn–3PUFA induces greater activation (P < 0.05) of the Akt–mTOR–S6K1 signalling pathway. Simultaneously, whole‐body total flux of phenylalanine was reduced from 87 to 67 μmol kg−1 h−1 (P= 0.04) and oxidative metabolism was decreased (P= 0.05). We conclude that chronic feeding of menhaden oil provides a novel nutritional mean to enhance insulin‐sensitive aspects of protein metabolism.
Neuroendocrine pathway involvement in the loss of the cutaneous pressure‐induced vasodilatation during acute pain in rats
Authors: Fromy Bérengère , Sigaudo‐Roussel Dominique , Baron Céline , Roquelaure Yves , Leftheriotis Georges , Saumet Jean Louis
Published: December 2006

Pain is regarded as a risk factor in pressure ulcer development by contributing to immobility. Pressure‐induced vasodilatation (PIV) is a mechanism whereby cutaneous blood flow increases in response to progressive locally applied pressure, thereby delaying the occurrence of ischaemia and appearing to be a protective response to local pressure. When the interaction between nervous and vascular systems is deregulated, PIV, which relies on both systems, is absent. We thus hypothesized that acute pain could alter PIV. This study investigated the effects on PIV of acute pain triggered by noxious heat (50°C) applied to the tail of anaesthetized rats. To address the mechanisms underlying these effects, chronic sympathectomy was performed using guanethidine, and the plasma concentrations of pituitary adrenocorticotrophin (ACTH) and catecholamines were measured. Our results show that acute pain induces a loss of PIV associated with an increase of ACTH. Direct involvement of hypertensive effects and peripheral sympathetic nervous system are excluded in the loss of PIV, whereas the activation of brain structures that have descending inhibitory control cannot be excluded. A low dose of systemic morphine prevented this loss of PIV and maintained the ability of the cutaneous microcirculation to adapt to the applied pressure. The loss of a protective response to local pressure (PIV) induced by acute pain lends physiological support to the direct involvement of pain in pressure ulcer development. Therefore, an adequate evaluation and treatment of pain is crucial.
Multiple sodium channels and their roles in electrogenesis within dorsal root ganglion neurons
Authors: Rush Anthony M. , Cummins Theodore R. , Waxman Stephen G.
Published: December 2006

Dorsal root ganglion neurons express an array of sodium channel isoforms allowing precise control of excitability. An increasing body of literature indicates that regulation of firing behaviour in these cells is linked to their patterns of expression of specific sodium channel isoforms, which have been discovered to possess distinct biophysical characteristics. The pattern of expression of sodium channels differs in different subclasses of DRG neurons and is not fixed but, on the contrary, changes in response to a variety of disease insults. Moreover, modulation of channels by their environment has been found to play an important role in the response of these neurons to stimuli. In this review we illustrate how excitability can be finely tuned to provide contrasting firing templates in different subclasses of DRG neurons by selective deployment of various sodium channel isoforms, by plasticity of expression of these proteins, and by interactions of these sodium channel isoforms with each other and with other modulatory molecules.
STIM1 regulates Ca2+ entry via arachidonate‐regulated Ca2+‐selective (ARC) channels without store depletion or translocation to the plasma membrane
Authors: Mignen Olivier , Thompson Jill L. , Shuttleworth Trevor J.
Published: December 2006

Recent studies have indicated a critical role for STIM (stromal interacting molecule) proteins in the regulation of the store‐operated mode of receptor‐activated Ca2+ entry. Current models emphasize the role of STIM located in the endoplasmic reticulum membrane, where a Ca2+‐binding EF‐hand domain within the N‐terminal of the protein lies within the lumen and is thought to represent the sensor for the depletion of intracellular Ca2+ stores. Dissociation of Ca2+ from this domain induces the aggregation of STIM to regions of the ER immediately adjacent to the plasma membrane where it acts to regulate the activity of store‐operated Ca2+ channels. However, the possible effects of STIM on other modes of receptor‐activated Ca2+ entry have not been examined. Here we show that STIM1 also regulates the arachidonic‐acid‐regulated Ca2+‐selective (ARC) channels – receptor‐activated Ca2+ entry channels whose activation is entirely independent of store depletion. Regulation of the ARC channels by STIM1 does not involve dissociation of Ca2+ from the EF‐hand, or any translocation of STIM1. Instead, a critical role of STIM1 resident in the plasma membrane is indicated. Thus, exposure of intact cells to an antibody targeting the extracellular N‐terminal domain of STIM1 inhibits ARC channel activity without significantly affecting the store‐operated channels. A similar specific inhibition of the ARC channels is seen in cells expressing a STIM1 construct in which the N‐linked glycosylation sites essential for the constitutive cell surface expression of STIM1, were mutated. We conclude that, in contrast to store‐operated channels, regulation of ARC channels by STIM1 depends exclusively on the pool of STIM1 constitutively residing in the plasma membrane. These data demonstrate that STIM1 is a more universal regulator of Ca2+ entry pathways than previously thought, and appears to have multiple modes of action.
Dendritic voltage‐gated K+ conductance gradient in pyramidal neurones of neocortical layer 5B from rats
Authors: Schaefer Andreas T. , Helmstaedter Moritz , Schmitt Arno C. , Bar‐Yehuda Dan , Almog Mara , Ben‐Porat Hana , Sakmann Bert , Korngreen Alon
Published: December 2006

Voltage‐gated potassium channels effectively regulate dendritic excitability in neurones. It has been suggested that in the distal apical dendrite of layer 5B (L5B) neocortical pyramidal neurones, K+ conductances participate in active dendritic synaptic integration and control regenerative dendritic potentials. The ionic mechanism for triggering these regenerative potentials has yet to be elucidated. Here we used two‐electrode voltage clamp (TEVC) to quantitatively record K+ conductance densities of a sustained K+ conductance in the soma and apical dendrite of L5B neurones of adult rats. We report that the somatic and proximal dendritic sustained voltage‐gated K+ conductance density is more than 10‐fold larger than previous estimates. The results obtained using TEVC were corroborated using current‐clamp experiments in combination with compartmental modelling. Possible error sources, including inaccurate measurement of the passive membrane parameters and unknown axonal and basal dendritic conductance distributions, were shown not to distort the density estimation considerably. The sustained voltage‐gated K+ conductance density was found to decrease steeply along the apical dendrite. The steep negative K+ conductance density gradient along the apical dendrite may help to define a distal, low‐threshold region for amplification of distal synaptic input in L5B pyramidal neurones.
Water transport by GLUT2 expressed in Xenopus laevis oocytes
Authors: Zeuthen Thomas , Zeuthen Emil , MacAulay Nanna
Published: December 2006

The glucose transporter GLUT2 has been shown to also transport water. In the present paper we investigated the relation between sugar and water transport in human GLUT2 expressed in Xenopus oocytes. Sugar transport was determined from uptakes of non‐metabolizable glucose analogues, primarily 3‐O‐methyl‐d‐glucopyranoside; key experimental results were confirmed using d(+)‐glucose. Water transport was derived from changes in oocyte volume monitored at a high resolution (20 pl, 1 s). Expression of GLUT2 induced a sugar permeability, PS, of about 5 × 10−6 cm s−1 and a passive water permeability, Lp, of 5.5 × 10−5 cm s−1. Accordingly, the passive water permeability of a GLUT2 protein is about 10 times higher than its sugar permeability. Both permeabilities were abolished by phloretin. Isosmotic addition of sugar to the bathing solution (replacing mannitol) induced two parallel components of water influx in GLUT2, one by osmosis and one by cotransport. The osmotic driving force arose from sugar accumulation at the intracellular side of the membrane and was given by an intracellular diffusion coefficient for sugar of 10−6 cm2 s−1, one‐fifth of the free solution value. The diffusion coefficient was determined in oocytes coexpressing GLUT2 and the water channel AQP1 where water transport was predominantly osmotic. By the cotransport mechanism about 35 water molecules were transported for each sugar molecule by a mechanism within the GLUT2. These water molecules could be transported uphill, against an osmotic gradient, energized by the flux of sugar. This capacity for cotransport is 10 times smaller than that of the Na+‐coupled glucose transporters (SGLT1). The physiological role of GLUT2 for intestinal transport under conditions of high luminal sugar concentrations is discussed.
Operation of a DNA Robot Arm Inserted into a 2D DNA Crystalline Substrate
Authors: Ding Baoquan , Seeman Nadrian C.
Published: December 2006

The success of nanorobotics requires the precise placement and subsequent operation of specific nanomechanical devices at particular locations. The structural programmability of DNA makes it a particularly attractive system for nanorobotics. We have developed a cassette that enables the placement of a robust, sequence-dependent DNA robot arm within a two-dimensional (2D) crystalline DNA array. The cassette contains the device, an attachment site, and a reporter of state. We used atomic force microscopy to demonstrate that the rotary device is fully functional after insertion. Thus, a nanomechanical device can operate within a fixed frame of reference.
U-Pb Isotopic Age of the StW 573 Hominid from Sterkfontein, South Africa
Authors: Walker Joanne , Cliff Robert A. , Latham Alfred G.
Published: December 2006

Sterkfontein cave, South Africa, has yielded an australopith skeleton, StW 573, whose completeness has excited great interest in paleoanthropology. StW 573, or “Little Foot,” was found 25 meters below the surface in the Silberberg Grotto.
238
U-
206
Pb measurements on speleothems immediately above and below the fossil remains, corrected for initial
234
U disequilibrium, yield ages of 2.17 ± 0.17 million years ago (Ma) and

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Ma, respectively, indicating an age for StW 573 of close to 2.2 Ma. This age is in contrast to an age of ∼3.3 Ma suggested by magnetochronology and ages of ∼4 Ma based on
10
Be and
26
Al, but it is compatible with a faunal age range of 4 to 2 Ma.
Carbon-Negative Biofuels from Low-Input High-Diversity Grassland Biomass
Authors: Tilman David , Hill Jason , Lehman Clarence
Published: December 2006

Biofuels derived from low-input high-diversity (LIHD) mixtures of native grassland perennials can provide more usable energy, greater greenhouse gas reductions, and less agrichemical pollution per hectare than can corn grain ethanol or soybean biodiesel. High-diversity grasslands had increasingly higher bioenergy yields that were 238% greater than monoculture yields after a decade. LIHD biofuels are carbon negative because net ecosystem carbon dioxide sequestration (4.4 megagram hectare
–1
year
–1
of carbon dioxide in soil and roots) exceeds fossil carbon dioxide release during biofuel production (0.32 megagram hectare
–1
year
–1
). Moreover, LIHD biofuels can be produced on agriculturally degraded lands and thus need to neither displace food production nor cause loss of biodiversity via habitat destruction.
Group Competition, Reproductive Leveling, and the Evolution of Human Altruism
Authors: Bowles Samuel
Published: December 2006

Humans behave altruistically in natural settings and experiments. A possible explanation—that groups with more altruists survive when groups compete—has long been judged untenable on empirical grounds for most species. But there have been no empirical tests of this explanation for humans. My empirical estimates show that genetic differences between early human groups are likely to have been great enough so that lethal intergroup competition could account for the evolution of altruism. Crucial to this process were distinctive human practices such as sharing food beyond the immediate family, monogamy, and other forms of reproductive leveling. These culturally transmitted practices presuppose advanced cognitive and linguistic capacities, possibly accounting for the distinctive forms of altruism found in our species.
Synthesis-Mediated Release of a Small RNA Inhibitor of RNA Polymerase
Authors: Wassarman Karen M. , Saecker Ruth M.
Published: December 2006

Noncoding small RNAs regulate gene expression in all organisms, in some cases through direct association with RNA polymerase (RNAP). Here we report that the mechanism of 6
S
RNA inhibition of transcription is through specific, stable interactions with the active site of
Escherichia coli
RNAP that exclude promoter DNA binding. In fact, the DNA-dependent RNAP uses bound 6
S
RNA as a template for RNA synthesis, producing 14-to 20-nucleotide RNA products (pRNA). These results demonstrate that 6
S
RNA is functionally engaged in the active site of RNAP. Synthesis of pRNA destabilizes 6
S
RNA–RNAP complexes leading to release of the pRNA-6
S
RNA hybrid. In vivo, 6
S
RNA–directed RNA synthesis occurs during outgrowth from the stationary phase and likely is responsible for liberating RNAP from 6
S
RNA in response to nutrient availability.
Late-Neoproterozoic Deep-Ocean Oxygenation and the Rise of Animal Life
Authors: Canfield Don E. , Poulton Simon W. , Narbonne Guy M.
Published: December 2006

Because animals require oxygen, an increase in late-Neoproterozoic oxygen concentrations has been suggested as a stimulus for their evolution. The iron content of deep-sea sediments shows that the deep ocean was anoxic and ferruginous before and during the Gaskiers glaciation 580 million years ago and that it became oxic afterward. The first known members of the Ediacara biota arose shortly after the Gaskiers glaciation, suggesting a causal link between their evolution and this oxygenation event. A prolonged stable oxic environment may have permitted the emergence of bilateral motile animals some 25 million years later.
Present-Day Impact Cratering Rate and Contemporary Gully Activity on Mars
Authors: Malin Michael C. , Edgett Kenneth S. , Posiolova Liliya V. , McColley Shawn M. , Dobrea Eldar Z. Noe
Published: December 2006

The Mars Global Surveyor Mars Orbiter Camera has acquired data that establish the present-day impact cratering rate and document new deposits formed by downslope movement of material in mid-latitude gullies on Mars. Twenty impacts created craters 2 to 150 meters in diameter within an area of 21.5 × 10
6
square kilometers between May 1999 and March 2006. The values predicted by models that scale the lunar cratering rate to Mars are close to the observed rate, implying that surfaces devoid of craters are truly young and that as yet unrecognized processes of denudation must be operating. The new gully deposits, formed since August 1999, are light toned and exhibit attributes expected from emplacement aided by a fluid with the properties of liquid water: relatively long, extended, digitate distal and marginal branches, diversion around obstacles, and low relief. The observations suggest that liquid water flowed on the surface of Mars during the past decade.
Organic Glasses with Exceptional Thermodynamic and Kinetic Stability
Authors: Swallen Stephen F. , Kearns Kenneth L. , Mapes Marie K. , Kim Yong Seol , McMahon Robert J. , Ediger M. D. , Wu Tian , Yu Lian , Satija Sushil
Published: December 2006

Vapor deposition has been used to create glassy materials with extraordinary thermodynamic and kinetic stability and high density. For glasses prepared from indomethacin or 1,3-bis-(1-naphthyl)-5-(2-naphthyl)benzene, stability is optimized when deposition occurs on substrates at a temperature of 50 K below the conventional glass transition temperature. We attribute the substantial improvement in thermodynamic and kinetic properties to enhanced mobility within a few nanometers of the glass surface during deposition. This technique provides an efficient means of producing glassy materials that are low on the energy landscape and could affect technologies such as amorphous pharmaceuticals.
Science Books for Fun and Learning--Some Recommendations from 2006
Authors: Malcomson Heather , Jasny Barbara , Suter Sherman
Published: December 2006

To aid those seeking gifts for younger readers, we present the 17 finalists for the four 2007
Science Books and Films
Prizes for Excellence in Science Books.

Science Books and Films
, 1200 New York Avenue, N.W., Washington DC, 20005, USA. E-mail:
hmalcoms@aaas.org
.
Identification of Translational Regulation Target Genes during Filamentous Growth in
Saccharomyces cerevisiae
: Regulatory Role of Caf20 and Dhh1
Authors: Park Young-Un , Hur Hyangsuk , Ka Minhan , Kim Jinmi
Published: December 2006

The dimorphic transition of yeast to the hyphal form is regulated by the mitogen-activated protein kinase and cyclic AMP-dependent protein kinase A pathways in
Saccharomyces cerevisiae
. Signaling pathway-responsive transcription factors such as Ste12, Tec1, and Flo8 are known to mediate filamentation-specific transcription. We were interested in investigating the translational regulation of specific mRNAs during the yeast-to-hyphal-form transition. Using polyribosome fractionation and RT-PCR analysis, we identified
STE12
,
GPA2
, and
CLN1
as translation regulation target genes during filamentous growth. The transcript levels for these genes did not change, but their mRNAs were preferentially associated with polyribosomes during the hyphal transition. The intracellular levels of Ste12, Gpa2, and Cln1 proteins increased under hyphal-growth conditions. The increase in Ste12 protein level was partially blocked by mutations in the
CAF20
and
DHH1
genes, which encode an eIF4E inhibitor and a decapping activator, respectively. In addition, the
caf20
and
dhh1
mutations resulted in defects in filamentous growth. The filamentation defects caused by
caf20
and
dhh1
mutations were suppressed by
STE12
overexpression. These results suggest that Caf20 and Dhh1 control yeast filamentation by regulating
STE12
translation.
Activity of a Second
Trypanosoma brucei
Hexokinase Is Controlled by an 18-Amino-Acid C-Terminal Tail
Authors: Morris Meredith T. , DeBruin Courtney , Yang Zhaoqing , Chambers Jeremy W. , Smith Kerry S. , Morris James C.
Published: December 2006

Trypanosoma brucei
expresses two hexokinases that are 98% identical, namely, TbHK1 and TbHK2. Homozygous null TbHK2
−/−
procyclic-form parasites exhibit an increased doubling time, a change in cell morphology, and, surprisingly, a twofold increase in cellular hexokinase activity. Recombinant TbHK1 enzymatic activity is similar to that of other hexokinases, with apparent

K
m

values for glucose and ATP of 0.09 ± 0.02 mM and 0.28 ± 0.1 mM, respectively. The
k
cat
value for TbHK1 is 2.9 × 10
4
min
−1
. TbHK1 can use mannose, fructose, 2-deoxyglucose, and glucosamine as substrates. In addition, TbHK1 is inhibited by fatty acids, with lauric, myristic, and palmitic acids being the most potent (with 50% inhibitory concentrations of 75.8, 78.4, and 62.4 μM, respectively). In contrast to TbHK1, recombinant TbHK2 lacks detectable enzymatic activity. Seven of the 10 amino acid differences between TbHK1 and TbHK2 lie within the C-terminal 18 amino acids of the polypeptides. Modeling of the proteins maps the C-terminal tails near the interdomain cleft of the enzyme that participates in the conformational change of the enzyme upon substrate binding. Replacing the last 18 amino acids of TbHK2 with the corresponding residues of TbHK1 yields an active recombinant protein with kinetic properties similar to those of TbHK1. Conversely, replacing the C-terminal tail of TbHK1 with the TbHK2 tail inactivates the enzyme. These findings suggest that the C-terminal tail of TbHK1 is important for hexokinase activity. The altered C-terminal tail of TbHK2, along with the phenotype of the knockout parasites, suggests a distinct function for the protein.