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Showing papers by "University of Maryland, College Park published in 2003"


Journal ArticleDOI
TL;DR: The Unified Theory of Acceptance and Use of Technology (UTAUT) as mentioned in this paper is a unified model that integrates elements across the eight models, and empirically validate the unified model.
Abstract: Information technology (IT) acceptance research has yielded many competing models, each with different sets of acceptance determinants. In this paper, we (1) review user acceptance literature and discuss eight prominent models, (2) empirically compare the eight models and their extensions, (3) formulate a unified model that integrates elements across the eight models, and (4) empirically validate the unified model. The eight models reviewed are the theory of reasoned action, the technology acceptance model, the motivational model, the theory of planned behavior, a model combining the technology acceptance model and the theory of planned behavior, the model of PC utilization, the innovation diffusion theory, and the social cognitive theory. Using data from four organizations over a six-month period with three points of measurement, the eight models explained between 17 percent and 53 percent of the variance in user intentions to use information technology. Next, a unified model, called the Unified Theory of Acceptance and Use of Technology (UTAUT), was formulated, with four core determinants of intention and usage, and up to four moderators of key relationships. UTAUT was then tested using the original data and found to outperform the eight individual models (adjusted R2 of 69 percent). UTAUT was then confirmed with data from two new organizations with similar results (adjusted R2 of 70 percent). UTAUT thus provides a useful tool for managers needing to assess the likelihood of success for new technology introductions and helps them understand the drivers of acceptance in order to proactively design interventions (including training, marketing, etc.) targeted at populations of users that may be less inclined to adopt and use new systems. The paper also makes several recommendations for future research including developing a deeper understanding of the dynamic influences studied here, refining measurement of the core constructs used in UTAUT, and understanding the organizational outcomes associated with new technology use.

27,798 citations


Journal ArticleDOI
TL;DR: In this paper, the authors provide an up-to-date critical survey of still-and video-based face recognition research, and provide some insights into the studies of machine recognition of faces.
Abstract: As one of the most successful applications of image analysis and understanding, face recognition has recently received significant attention, especially during the past several years. At least two reasons account for this trend: the first is the wide range of commercial and law enforcement applications, and the second is the availability of feasible technologies after 30 years of research. Even though current machine recognition systems have reached a certain level of maturity, their success is limited by the conditions imposed by many real applications. For example, recognition of face images acquired in an outdoor environment with changes in illumination and/or pose remains a largely unsolved problem. In other words, current systems are still far away from the capability of the human perception system.This paper provides an up-to-date critical survey of still- and video-based face recognition research. There are two underlying motivations for us to write this survey paper: the first is to provide an up-to-date review of the existing literature, and the second is to offer some insights into the studies of machine recognition of faces. To provide a comprehensive survey, we not only categorize existing recognition techniques but also present detailed descriptions of representative methods within each category. In addition, relevant topics such as psychophysical studies, system evaluation, and issues of illumination and pose variation are covered.

6,384 citations


Journal ArticleDOI
14 Mar 2003-Science
TL;DR: Enhanced polarization and related properties in heteroepitaxially constrained thin films of the ferroelectromagnet, BiFeO3, and combined functional responses in thin film form present an opportunity to create and implement thin film devices that actively couple the magnetic and ferroelectric order parameters.
Abstract: Enhancement of polarization and related properties in heteroepitaxially constrained thin films of the ferroelectromagnet, BiFeO3, is reported. Structure analysis indicates that the crystal structure of film is monoclinic in contrast to bulk, which is rhombohedral. The films display a room-temperature spontaneous polarization (50 to 60 microcoulombs per square centimeter) almost an order of magnitude higher than that of the bulk (6.1 microcoulombs per square centimeter). The observed enhancement is corroborated by first-principles calculations and found to originate from a high sensitivity of the polarization to small changes in lattice parameters. The films also exhibit enhanced thickness-dependent magnetism compared with the bulk. These enhanced and combined functional responses in thin film form present an opportunity to create and implement thin film devices that actively couple the magnetic and ferroelectric order parameters.

5,387 citations


Journal ArticleDOI
TL;DR: The Global Precipitation Climatology Project (GPCP) version 2 Monthly Precise Analysis as discussed by the authors is a merged analysis that incorporates precipitation estimates from low-orbit satellite microwave data, geosynchronous-orbit-satellite infrared data, and rain gauge observations.
Abstract: The Global Precipitation Climatology Project (GPCP) Version 2 Monthly Precipitation Analysis is described. This globally complete, monthly analysis of surface precipitation at 2.5 degrees x 2.5 degrees latitude-longitude resolution is available from January 1979 to the present. It is a merged analysis that incorporates precipitation estimates from low-orbit-satellite microwave data, geosynchronous-orbit-satellite infrared data, and rain gauge observations. The merging approach utilizes the higher accuracy of the low-orbit microwave observations to calibrate, or adjust, the more frequent geosynchronous infrared observations. The data set is extended back into the premicrowave era (before 1987) by using infrared-only observations calibrated to the microwave-based analysis of the later years. The combined satellite-based product is adjusted by the raingauge analysis. This monthly analysis is the foundation for the GPCP suite of products including those at finer temporal resolution, satellite estimate, and error estimates for each field. The 23-year GPCP climatology is characterized, along with time and space variations of precipitation.

4,951 citations


Journal ArticleDOI
TL;DR: The core ideology of conservatism stresses resistance to change and justification of inequality and is motivated by needs that vary situationally and dispositionally to manage uncertainty and threat.
Abstract: Analyzing political conservatism as motivated social cognition integrates theories of personality (authoritarianism, dogmatism-intolerance of ambiguity), epistemic and existential needs (for closure, regulatory focus, terror management), and ideological rationalization (social dominance, system justification). A meta-analysis (88 samples, 12 countries, 22,818 cases) confirms that several psychological variables predict political conservatism: death anxiety (weighted mean r = .50); system instability (.47); dogmatism-intolerance of ambiguity (.34); openness to experience (-.32); uncertainty tolerance (-.27); needs for order, structure, and closure (.26); integrative complexity (-.20); fear of threat and loss (.18); and self-esteem (-.09). The core ideology of conservatism stresses resistance to change and justification of inequality and is motivated by needs that vary situationally and dispositionally to manage uncertainty and threat.

3,745 citations



Journal ArticleDOI
TL;DR: Converging evidence from diverse methodological and analytic strategies verifies that perceived self-efficacy and personal goals enhance motivation and performance attainments.
Abstract: The authors address the verification of the functional properties of self-efficacy beliefs and document how self-efficacy beliefs operate in concert with goal systems within a sociocognitive theory of self-regulation in contrast to the focus of control theory on discrepancy reduction. Social cognitive theory posits proactive discrepancy production by adoption of goal challenges working in concert with reactive discrepancy reduction in realizing them. Converging evidence from diverse methodological and analytic strategies verifies that perceived self-efficacy and personal goals enhance motivation and performance attainments. The large body of evidence, as evaluated by 9 meta-analyses for the effect sizes of self-efficacy beliefs and by the vast body of research on goal setting, contradicts findings (J. B. Vancouver, C. M. Thompson, & A. A. Williams, 2001; J. B. Vancouver, C. M. Thompson, E. C. Tischner, & D. J. Putka, 2002) that belief in one’s capabilities and personal goals is self-debilitating. Social cognitive theory is rooted in an agentic perspective in which people function as anticipative, purposive, and selfevaluating proactive regulators of their motivation and actions (Bandura, 2001). A theory embodying feed-forward selfregulation differs from control theories rooted solely in a negative feedback control system aimed at error correction. Among the mechanisms of human agency, none is more central or pervasive than beliefs of personal efficacy. Whatever other factors serve as guides and motivators, they are rooted in the core belief that one has the power to produce desired effects; otherwise one has little incentive to act or to persevere in the face of difficulties. Selfefficacy beliefs regulate human functioning through cognitive, motivational, affective, and decisional processes (Bandura, 1997). They affect whether individuals think in self-enhancing or selfdebilitating ways, how well they motivate themselves and persevere in the face of difficulties, the quality of their emotional well-being and their vulnerability to stress and depression, and the choices they make at important decisional points.

2,530 citations


Journal ArticleDOI
29 May 2003-Nature
TL;DR: The difference between trends in observed surface temperatures in the continental United States and the corresponding trends in a reconstruction of surface temperatures determined from a reanalysis of global weather over the past 50 years is used to estimate the impact of land-use changes on surface warming.
Abstract: The most important anthropogenic influences on climate are the emission of greenhouse gases1 and changes in land use, such as urbanization and agriculture2. But it has been difficult to separate these two influences because both tend to increase the daily mean surface temperature3,4. The impact of urbanization has been estimated by comparing observations in cities with those in surrounding rural areas, but the results differ significantly depending on whether population data5 or satellite measurements of night light6,7,8 are used to classify urban and rural areas7,8. Here we use the difference between trends in observed surface temperatures in the continental United States and the corresponding trends in a reconstruction of surface temperatures determined from a reanalysis of global weather over the past 50 years, which is insensitive to surface observations, to estimate the impact of land-use changes on surface warming. Our results suggest that half of the observed decrease in diurnal temperature range is due to urban and other land-use changes. Moreover, our estimate of 0.27 °C mean surface warming per century due to land-use changes is at least twice as high as previous estimates based on urbanization alone7,8.

2,018 citations


Journal ArticleDOI
TL;DR: There appears to be at least three different populations of activated macrophages with three distinct biological functions, the most recent addition is the type 2-activated macrophage, which is anti-inflammatory and preferentially induces Th2-type humoral-immune responses to antigen.
Abstract: It used to be easy. In the old days ( 8 years ago), activated macrophages were simply defined as cells that secreted inflammatory mediators and killed intracellular pathogens. Things are becoming progressively more complicated in the world of leukocyte biology. Activated macrophages may be a more heterogenous group of cells than originally appreciated, with different physiologies and performing distinct immunological functions. The first hint of this heterogeneity came with the characterization of the “alternatively activated macrophage” [1]. The exposure of macrophages to interleukin (IL)-4 or glucocorticoids induced a population of cells that up-regulated certain phagocytic receptors but failed to produce nitrogen radicals [2] and as a result, were relatively poor at killing intracellular pathogens. Recent studies have shown that these alternatively activated cells produce several components involved in the synthesis of the extracellular matrix (ECM) [3], suggesting their primary role may be involved in tissue repair rather than microbial killing. It turns out that the name alternatively activated macrophage may be unfortunate for a few reasons. First, although these cells express some markers of activation, they have not been exposed to the classical, activating stimuli, interferon(IFN) and lipopolysaccharide (LPS). Second, and more importantly, the name implies that this is the only other way to activate a macrophage. Recent studies suggest that this may not be the case. Exposure of macrophages to classical activating signals in the presence of immunoglobulin G (IgG) immune complexes induced the production of a cell type that was fundamentally different from the classically activated macrophage. These cells generated large amounts of IL-10 and as a result, were potent inhibitors of acute inflammatory responses to bacterial endotoxin [4]. These activated macrophages have been called type 2-activated macrophages [5] because of their ability to induce T helper cell type 2 (Th2) responses that were predominated by IL-4 [6], leading to IgG class-switching by B cells. Thus, at this time, there appears to be at least three different populations of activated macrophages with three distinct biological functions. The first and most well described is the classically activated macrophage whose role is as an effector cell in Th1 cellular immune responses. The second type of cell, the alternatively activated macrophage, appears to be involved in immunosuppression and tissue repair. The most recent addition to this list is the type 2-activated macrophage, which is anti-inflammatory and preferentially induces Th2-type humoral-immune responses to antigen. Together, these three populations of cells may form their own regulatory network to prevent a well-intentioned immune response from progressing to immunopathology. THE CLASSICALLY ACTIVATED MACROPHAGE

1,903 citations


Journal ArticleDOI
TL;DR: In this paper, the authors developed a switching cost typology that identifies three types of switching costs: (1) procedural switching costs, primarily involving the loss of time and effort; (2) financial switching costs involving loss of financially quantifiable resources; and (3) relational switching cost, involving psychological or emotional discomfort due to the loss or identity and the breaking of bonds, and concluded that consumers' perceptions of product complexity and provider heterogeneity, their breadth of product use, and their alternative provider and switching experience drive the switching costs they perceive.
Abstract: The management of customer switching costs has been hampered by the lack of a comprehensive typology for conceptualizing, categorizing, and measuring consumers' perceptions of these costs. This research develops a switching cost typology that identifies three types of switching costs: (1) procedural switching costs, primarily involving the loss of time and effort; (2) financial switching costs, involving the loss of financially quantifiable resources; and (3) relational switching costs, involving psychological or emotional discomfort due to the loss of identity and the breaking of bonds. The research then examines the antecedents and consequences of switching costs. The results suggest that consumers' perceptions of product complexity and provider heterogeneity, their breadth of product use, and their alternative provider and switching experience drive the switching costs they perceive. Furthermore, all three switching cost types significantly influence consumers' intentions to stay with their current service provider, explaining more variance than does satisfaction.

1,715 citations


Journal ArticleDOI
TL;DR: In this article, the authors explain the importance of examining entrepreneurship through a disequilibrium framework that focuses on the characteristics and existence of entrepreneurial opportunities, and describe several typologies of opportunities and their implications for understanding entrepreneurship.

Journal ArticleDOI
TL;DR: In this paper, the authors propose a conceptual framework and develop hypotheses about the effects of the online medium on customer satisfaction and loyalty and on the relationships between satisfaction and loyalties.

Journal ArticleDOI
TL;DR: An improved replacement detection algorithm is presented that offers increased sensitivity to smaller, cooler fires as well as a significantly lower false alarm rate.

Journal ArticleDOI
TL;DR: This ecologic study reveals that urban form could be significantly associated with some forms of physical activity and some health outcomes.
Abstract: Purpose. To determine the relationship between urban sprawl, health, and health-related behaviors. Design. Cross-sectional analysis using hierarchical modeling to relate characteristics of individuals and places to levels of physical activity, obesity, body mass index (BMI), hypertension, diabetes, and coronary heart disease. Setting. U.S. counties (448) and metropolitan areas (83). Subjects. Adults (n 5 206,992) from pooled 1998, 1999, and 2000 Behavioral Risk Factor Surveillance System (BRFSS). Measures. Sprawl indices, derived with principal components analysis from census and other data, served as independent variables. Self-reported behavior and health status from BRFSS served as dependent variables. Results. After controlling for demographic and behavioral covariates, the county sprawl index had small but significant associations with minutes walked (p 5 .004), obesity (p , .001), BMI (p 5 .005), and hypertension (p 5 .018). Residents of sprawling counties were likely to walk less during leisure time, weigh more, and have greater prevalence of hypertension than residents of compact counties. At the metropolitan level, sprawl was similarly associated with minutes walked (p 5 .04) but not with the other variables. Conclusion. This ecologic study reveals that urban form could be significantly associated with some forms of physical activity and some health outcomes. More research is needed to refine measures of urban form, improve measures of physical activity, and control for other individual and environmental influences on physical activity, obesity, and related health outcomes. (Am J Health Promot 2003;18[1]:47‐57.)

Journal ArticleDOI
TL;DR: The algorithm of the Program to Assemble Spliced Alignments (PASA) tool is described, as well as the results of automated updates to Arabidopsis gene annotations.
Abstract: The spliced alignment of expressed sequence data to genomic sequence has proven a key tool in the comprehensive annotation of genes in eukaryotic genomes. A novel algorithm was developed to assemble clusters of overlapping transcript alignments (ESTs and full-length cDNAs) into maximal alignment assemblies, thereby comprehensively incorporating all available transcript data and capturing subtle splicing variations. Complete and partial gene structures identified by this method were used to improve The Institute for Genomic Research Arabidopsis genome annotation (TIGR release v.4.0). The alignment assemblies permitted the automated modeling of several novel genes and >1000 alternative splicing variations as well as updates (including UTR annotations) to nearly half of the ~27 000 annotated protein coding genes. The algorithm of the Program to Assemble Spliced Alignments (PASA) tool is described, as well as the results of automated updates to Arabidopsis gene annotations.

Journal ArticleDOI
TL;DR: Biomedicalization describes the increasingly complex, multisited, multidirectional processes of medicalization, both extended and reconstituted through the new social forms of highly technoscientific biomedicine.
Abstract: The first social transformation of American medicine institutionally established medicine by the end of World War II. In the next decades, medicalization-the expansion of medical jurisdiction, authority, and practices into new realms-became widespread. Since about 1985, dramatic changes in both the organization and practices of contemporary biomedicine, implemented largely through the integration of technoscientific innovations, have been coalescing into what the authors call biomedicalization, a second transformation of American medicine. Biomedicalization describes the increasingly complex, multisited, multidirectional processes of medicalization, both extended and reconstituted through the new social forms of highly technoscientific biomedicine. The historical shift from medicalization to biomedicalization is one from control over biomedical phenomena to transformations of them. Five key interactive processes both engender biomedicalization and are produced through it: (1) the political economic reconstitution of the vast sector of biomedicine; (2) the focus on health itself and the elaboration of risk and surveillance biomedicines; (3) the increasingly technological and scientific nature of biomedicine; (4) transformations in how biomedical knowledges are produced, distributed, and consumed, and in medical information management; and (5) transformations of bodies to include new properties and the production of new individual and collective technoscientific identities.

Journal ArticleDOI
TL;DR: Based on the excellent radiometric and spectral performance demonstrated by AIRS during prelaunch testing, it is expected the assimilation of AIRS data into the numerical weather forecast to result in significant forecast range and reliability improvements.
Abstract: The Atmospheric Infrared Sounder (AIRS), the Advanced Microwave Sounding Unit (AMSU), and the Humidity Sounder for Brazil (HSB) form an integrated cross-track scanning temperature and humidity sounding system on the Aqua satellite of the Earth Observing System (EOS). AIRS is an infrared spectrometer/radiometer that covers the 3.7-15.4-/spl mu/m spectral range with 2378 spectral channels. AMSU is a 15-channel microwave radiometer operating between 23 and 89 GHz. HSB is a four-channel microwave radiometer that makes measurements between 150 and 190 GHz. In addition to supporting the National Aeronautics and Space Administration's interest in process study and climate research, AIRS is the first hyperspectral infrared radiometer designed to support the operational requirements for medium-range weather forecasting of the National Ocean and Atmospheric Administration's National Centers for Environmental Prediction (NCEP) and other numerical weather forecasting centers. AIRS, together with the AMSU and HSB microwave radiometers, will achieve global retrieval accuracy of better than 1 K in the lower troposphere under clear and partly cloudy conditions. This paper presents an overview of the science objectives, AIRS/AMSU/HSB data products, retrieval algorithms, and the ground-data processing concepts. The EOS Aqua was launched on May 4, 2002 from Vandenberg AFB, CA, into a 705-km-high, sun-synchronous orbit. Based on the excellent radiometric and spectral performance demonstrated by AIRS during prelaunch testing, which has by now been verified during on-orbit testing, we expect the assimilation of AIRS data into the numerical weather forecast to result in significant forecast range and reliability improvements.

Journal ArticleDOI
23 Apr 2003-JAMA
TL;DR: Both behavioral interventions significantly reduced weight, improved fitness, and lowered sodium intake and the established plus DASH intervention also increased fruit, vegetable, and dairy intake.
Abstract: CONTEXT Weight loss, sodium reduction, increased physical activity, and limited alcohol intake are established recommendations that reduce blood pressure (BP). The Dietary Approaches to Stop Hypertension (DASH) diet also lowers BP. To date, no trial has evaluated the effects of simultaneously implementing these lifestyle recommendations. OBJECTIVE To determine the effect on BP of 2 multicomponent, behavioral interventions. DESIGN, SETTING, AND PARTICIPANTS Randomized trial with enrollment at 4 clinical centers (January 2000-June 2001) among 810 adults (mean [SD] age, 50 [8.9] years; 62% women; 34% African American) with above-optimal BP, including stage 1 hypertension (120-159 mm Hg systolic and 80-95 mm Hg diastolic), and who were not taking antihypertensive medications. INTERVENTION Participants were randomized to one of 3 intervention groups: (1) "established," a behavioral intervention that implemented established recommendations (n = 268); (2) "established plus DASH,"which also implemented the DASH diet (n = 269); and (3) an "advice only" comparison group (n = 273). MAIN OUTCOME MEASURES Blood pressure measurement and hypertension status at 6 months. RESULTS Both behavioral interventions significantly reduced weight, improved fitness, and lowered sodium intake. The established plus DASH intervention also increased fruit, vegetable, and dairy intake. Across the groups, gradients in BP and hypertensive status were evident. After subtracting change in advice only, the mean net reduction in systolic BP was 3.7 mm Hg (P<.001) in the established group and 4.3 mm Hg (P<.001) in the established plus DASH group; the systolic BP difference between the established and established plus DASH groups was 0.6 mm Hg (P =.43). Compared with the baseline hypertension prevalence of 38%, the prevalence at 6 months was 26% in the advice only group, 17% in the established group (P =.01 compared with the advice only group), and 12% in the established plus DASH group (P<.001 compared with the advice only group; P =.12 compared with the established group). The prevalence of optimal BP (<120 mm Hg systolic and <80 mm Hg diastolic) was 19% in the advice only group, 30% in the established group (P =.005 compared with the advice only group), and 35% in the established plus DASH group (P<.001 compared with the advice only group; P =.24 compared with the established group). CONCLUSION Individuals with above-optimal BP, including stage 1 hypertension, can make multiple lifestyle changes that lower BP and reduce their cardiovascular disease risk.

Proceedings ArticleDOI
05 Apr 2003
TL;DR: A new method for use in the process of co-designing technologies with users called technology probes, which are simple, flexible, adaptable technologies with three interdisciplinary goals: the social science goal of understanding the needs and desires of users in a real-world setting, the engineering goal of field-testing the technology, and the design goal of inspiring users and researchers to think about new technologies.
Abstract: We describe a new method for use in the process of co-designing technologies with users called technology probes. Technology probes are simple, flexible, adaptable technologies with three interdisciplinary goals: the social science goal of understanding the needs and desires of users in a real-world setting, the engineering goal of field-testing the technology, and the design goal of inspiring users and researchers to think about new technologies. We present the results of designing and deploying two technology probes, the messageProbe and the videoProbe, with diverse families in France, Sweden, and the U.S. We conclude with our plans for creating new technologies for and with families based on our experiences.

Journal ArticleDOI
TL;DR: An elegant and remarkably simple algorithm ("the threshold algorithm", or TA) is analyzed that is optimal in a much stronger sense than FA, and is essentially optimal, not just for some monotone aggregation functions, but for all of them, and not just in a high-probability worst-case sense, but over every database.

Journal ArticleDOI
TL;DR: Although many view iterative and incremental development as a modern practice, its application dates as far back as the mid-1950s, with prominent software-engineering thought leaders from each succeeding decade supporting IID practices.
Abstract: Although many view iterative and incremental development as a modern practice, its application dates as far back as the mid-1950s. Prominent software-engineering thought leaders from each succeeding decade supported IID practices, and many large projects used them successfully. These practices may have differed in their details, but all had a common theme-to avoid a single-pass sequential, document-driven, gated-step approach.

Journal ArticleDOI
TL;DR: In this article, the authors compare four different explanations for cross-institutional variation in new firm formation rates from university technology licensing offices (TLO) over the 1994-1998 period, including the availability of venture capital in the university area, the commercial orientation of university research and development, intellectual eminence, and university policies.

Journal ArticleDOI
TL;DR: The authors examined individual behavior in two well-functioning marketplaces to investigate whether market experience eliminates the endowment effect and found that individual behavior converges to the neoclassical prediction as market experience increases.
Abstract: This study examines individual behavior in two well-functioning marketplaces to investigate whether market experience eliminates the endowment effect. Field evidence from both markets suggests that individual behavior converges to the neoclassical prediction as market experience increases. In an experimental test of whether these observations are due to treatment (market experience) or selection (e.g., static preferences), I end that market experience plays a signiecant role in eliminating the endowment effect. I also end that these results are robust to institutional change and extend beyond the two marketplaces studied. Overall, this study provides strong evidence that market experience eliminates an important market anomaly.

Journal ArticleDOI
TL;DR: The Conformity to Masculine Norms Inventory (CMNI) as discussed by the authors is a self-reported measure of men's mental health and self-confidence, which measures the desire to be more muscular.
Abstract: This article describes the construction of the Conformity to Masculine Norms Inventory (CMNI), and 5 studies that examined its psychometric properties. Factor analysis indicated 11 distinct factors: Winning, Emotional Control, Risk-Taking, Violence, Dominance, Playboy, Self-Reliance, Primacy of Work, Power Over Women, Disdain for Homosexuals, and Pursuit of Status. Results from Studies 2-5 indicated that the CMNI had strong internal consistency estimates and good differential validity comparing men with women and groups of men on health-related questions; all of the CMNI subscales were significantly and positively related to other masculinity-related measures, with several subscales being related significantly and positively to psychological distress, social dominance, aggression, and the desire to be more muscular, and significantly and negatively to attitudes toward psychological help seeking and social desirability; and CMNI scores had high test-retest estimates for a 2-3 week period.

Journal ArticleDOI
24 Jul 2003-Nature
TL;DR: This work reports on the construction and successful operation of a fully synthetic nanoscale electromechanical actuator incorporating a rotatable metal plate, with a multi-walled carbon nanotube serving as the key motion-enabling element.
Abstract: Nanostructures are of great interest not only for their basic scientific richness, but also because they have the potential to revolutionize critical technologies. The miniaturization of electronic devices over the past century has profoundly affected human communication, computation, manufacturing and transportation systems. True molecular-scale electronic devices are now emerging that set the stage for future integrated nanoelectronics. Recently, there have been dramatic parallel advances in the miniaturization of mechanical and electromechanical devices. Commercial microelectromechanical systems now reach the submillimetre to micrometre size scale, and there is intense interest in the creation of next-generation synthetic nanometre-scale electromechanical systems. We report on the construction and successful operation of a fully synthetic nanoscale electromechanical actuator incorporating a rotatable metal plate, with a multi-walled carbon nanotube serving as the key motion-enabling element.

Journal ArticleDOI
TL;DR: The 'asymmetric sampling in time' hypothesis developed here provides a framework for understanding a range of psychophysical and neuropsychological data on speech perception in the context of a revised cortical functional anatomic model.

Journal ArticleDOI
TL;DR: In this paper, the authors provided an analytic approximation for Pmin as a function of metallicity, far-ultraviolet radiation field, and the ionization rate of atomic hydrogen.
Abstract: Much of the interstellar medium in disk galaxies is in the form of neutral atomic hydrogen, H i. This gas can be in thermal equilibrium at relatively low temperatures, Td300 K (the cold neutral medium (CNM)), or at temperatures somewhat less than 10 4 K (the warm neutral medium (WNM)). These two phases can coexist over a narrow range of pressures, PminPPmax. We determine Pmin and Pmax in the plane of the Galaxy as a function of Galactocentric radius R using recent determinations of the gas heating rate and the gas-phase abundances of interstellar gas. We provide an analytic approximation for Pmin as a function of metallicity, far-ultraviolet radiation field, and the ionization rate of atomic hydrogen. Our analytic results show that the existence of Pmin, or the possibility of a two-phase equilibrium, generally requires that H + exceed C + in abundance at Pmin. The abundance of H + is set by EUV/soft X-ray photoionization and by recombination with negatively charged polycyclic aromatic hydrocarbons. In order to assess whether thermal or pressure equilibrium is a realistic assumption, we define a parameter � � tcool=tshock, where tcool is the gas cooling time and tshock is the characteristic shock time or '' time between shocks in a turbulent medium.'' For � < 1 gas has time to reach thermal balance between supernova-induced shocks. We find that this condition is satisfied in the Galactic disk, and thus the two-phase description of the interstellar H i is approximately valid even in the presence of interstellar turbulence. Observationally, the mean density nHi hi is often better determined than the local density, and we cast our results in terms of nHi hi as well. Over most of the disk of the Galaxy, the Hi must be in two phases: the weight of the Hi in the gravitational potential of the Galaxy is large enough to generate thermal pressures exceeding Pmin, so that turbulent pressure fluctuations can produce cold gas that is thermally stable; and the mean density of the H i is too low for the gas to be all CNM. Our models predict the presence of CNM gas to R ' 16 18 kpc, somewhat farther than previous estimates. An estimate for the typical thermal pressure in the Galactic plane for 3 kpcdRd18 kpc is Pth=k ' 1:4 � 10 4 expð� R=5:5 kpcÞ Kc m � 3 . At the solar circle, this gives Pth=k ' 3000 K cm � 3 . We show that this pressure is consistent with the C i*/C itot ratio observed by Jenkins & Tripp and the CNM temperature found by Heiles & Troland. We also examine the potential impact of turbulent heating on our results and provide parameterized expressions for the heating rate as a function of Galactic radius. Although the uncertainties are large, our models predict that including turbulent heating does not significantly change our results and that thermal pressures remain above Pmin to R ' 18 kpc. Subject headings: ISM: clouds — ISM: general — ISM: structure

Journal ArticleDOI
TL;DR: The authors identified 9 characteristics that were consistently associated with effective prevention programs that can inform the planning and implementation of problem-specific prevention interventions, provide a rationale for multi-problem prevention programs, and serve as a basis for further research.
Abstract: The high prevalence of drug abuse, delinquency, youth violence, and other youth problems creates a need to identify and disseminate effective prevention strategies. General principles gleaned from effective interventions may help prevention practitioners select, modify, or create more effective programs. Using a review-of-reviews approach across 4 areas (substance abuse, risky sexual behavior, school failure, and juvenile delinquency and violence), the authors identified 9 characteristics that were consistently associated with effective prevention programs: Programs were comprehensive, included varied teaching methods, provided sufficient dosage, were theory driven, provided opportunities for positive relationships, were appropriately timed, were socioculturally relevant, included outcome evaluation, and involved well-trained staff. This synthesis can inform the planning and implementation of problem-specific prevention interventions, provide a rationale for multi-problem prevention programs, and serve as a basis for further research.

Journal ArticleDOI
TL;DR: It is suggested that beliefs about technology use can be influenced by top management commitment to new technology and the individual factors of personal innovativeness and self-efficacy and the context of a contemporary technology targeted at autonomous knowledge workers.
Abstract: Individual beliefs about technology use have been shown to have a profound impact on subsequent behaviors toward information technology (IT). This research note builds upon and extends prior research examining factors that influence key individual beliefs about technology use. It is argued that individuals form beliefs about their use of information technologies within a broad milieu of influences emanating from the individual, institutional, and social contexts in which they interact with IT. We examine the simultaneous effects of these three sets of influences on beliefs about usefulness and ease of use in the context of a contemporary technology targeted at autonomous knowledge workers. Our findings suggest that beliefs about technology use can be influenced by top management commitment to new technology and the individual factors of personal innovativeness and self-efficacy. Surprisingly, social influences from multiple sources exhibited no significant effects. Theoretical and practical implications are offered.

Journal ArticleDOI
TL;DR: The first results of the MODIS vegetation continuous field algorithm's global percent tree cover are presented in this article, where a supervised regression tree algorithm is used to estimate tree cover per 500m MODIS pixel.
Abstract: The first results of the Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation continuous field algorithm's global percent tree cover are presented. Percent tree cover per 500-m MODIS pixel is estimated using a supervised regression tree algorithm. Data derived from the MODIS visible bands contribute the most to discriminating tree cover. The results show that MODIS data yield greater spatial detail in the characterization of tree cover compared to past efforts using AVHRR data. This finer-scale depiction should allow for using successive tree cover maps in change detection studies at the global scale. Initial validation efforts show a reasonable relationship between the MODIS-estimated tree cover and tree cover from validation sites.