Showing papers by "Arizona State University published in 2006"

Exceptional chemical and thermal stability of zeolitic imidazolate frameworks

Abstract: Twelve zeolitic imidazolate frameworks (ZIFs; termed ZIF-1 to -12) have been synthesized as crystals by copolymerization of either Zn(II) (ZIF-1 to -4, -6 to -8, and -10 to -11) or Co(II) (ZIF-9 and -12) with imidazolate-type links. The ZIF crystal structures are based on the nets of seven distinct aluminosilicate zeolites: tetrahedral Si(Al) and the bridging O are replaced with transition metal ion and imidazolate link, respectively. In addition, one example of mixed-coordination imidazolate of Zn(II) and In(III) (ZIF-5) based on the garnet net is reported. Study of the gas adsorption and thermal and chemical stability of two prototypical members, ZIF-8 and -11, demonstrated their permanent porosity (Langmuir surface area = 1,810 m 2 /g), high thermal stability (up to 550°C), and remarkable chemical resistance to boiling alkaline water and organic solvents.

The Reification of Absorptive Capacity: A Critical Review and Rejuvenation of the Construct

Abstract: We conduct a detailed analysis of 289 absorptive capacity papers from 14 journals to assess how the construct has been utilized, examine the key papers in the field, and identify the substantive contributions to the broader literature using a thematic analysis. We argue that research in this area is fundamentally driven by five critical assumptions that we conclude have led to its reification and that this reification has led to stifling of research in this area. To address this, we propose a model of absorptive capacity processes, antecedents, and outcomes.

GeoDa: An Introduction to Spatial Data Analysis

Abstract: The development of specialized software for spatial data analysis has seen rapid growth since the lack of such tools was lamented in the late 1980s by Haining (1989) and cited as a major impediment to the adoption and use of spatial statistics by GIS researchers. Initially, attention tended to focus on conceptual issues, such as how to integrate spatial statistical methods and a GIS environment (loosely vs. tightly coupled, embedded vs. modular, etc.), and which techniques would be most fruitfully included in such a framework. Familiar reviews of these issues are represented in, among others, Anselin and Getis (1992), Goodchild et al. (1992), Fischer and Nijkamp (1993), Fotheringham and Rogerson (1993, 1994), Fischer et al. (1996), and Fischer and Getis (1997). Today, the situation is quite different, and a fairly substantial collection of spatial data analysis software is readily available, ranging from niche programs, customized scripts and extensions for commercial statistical and GIS packages, to a burgeoning open source effort using software environments such as R, Java and Python. This is exemplified by the growing contents of the software tools clearing house maintained by the U.S.- based Center for Spatially Integrated Social Science [CSISS] (see http://www.csiss.org/clearinghouse/).

A new version of detached-eddy simulation, resistant to ambiguous grid densities

Abstract: Detached-eddy simulation (DES) is well understood in thin boundary layers, with the turbulence model in its Reynolds-averaged Navier–Stokes (RANS) mode and flattened grid cells, and in regions of massive separation, with the turbulence model in its large-eddy simulation (LES) mode and grid cells close to isotropic. However its initial formulation, denoted DES97 from here on, can exhibit an incorrect behavior in thick boundary layers and shallow separation regions. This behavior begins when the grid spacing parallel to the wall Δ∥ becomes less than the boundary-layer thickness δ, either through grid refinement or boundary-layer thickening. The grid spacing is then fine enough for the DES length scale to follow the LES branch (and therefore lower the eddy viscosity below the RANS level), but resolved Reynolds stresses deriving from velocity fluctuations (“LES content”) have not replaced the modeled Reynolds stresses. LES content may be lacking because the resolution is not fine enough to fully support it, and/or because of delays in its generation by instabilities. The depleted stresses reduce the skin friction, which can lead to premature separation.

Two-Year Randomized Controlled Trial and Follow-up of Dialectical Behavior Therapy vs Therapy by Experts for Suicidal Behaviors and Borderline Personality Disorder

Abstract: Context Dialectical behavior therapy (DBT) is a treatment for suicidal behavior and borderline personality disorder with well-documented efficacy. Objective To evaluate the hypothesis that unique aspects of DBT are more efficacious compared with treatment offered by non–behavioral psychotherapy experts. Design One-year randomized controlled trial, plus 1 year of posttreatment follow-up. Setting University outpatient clinic and community practice. Participants One hundred one clinically referred women with recent suicidal and self-injurious behaviors meeting DSM-IV criteria, matched to condition on age, suicide attempt history, negative prognostic indication, and number of lifetime intentional self-injuries and psychiatric hospitalizations. Intervention One year of DBT or 1 year of community treatment by experts (developed to maximize internal validity by controlling for therapist sex, availability, expertise, allegiance, training and experience, consultation availability, and institutional prestige). Main Outcome Measures Trimester assessments of suicidal behaviors, emergency services use, and general psychological functioning. Measures were selected based on previous outcome studies of DBT. Outcome variables were evaluated by blinded assessors. Results Dialectical behavior therapy was associated with better outcomes in the intent-to-treat analysis than community treatment by experts in most target areas during the 2-year treatment and follow-up period. Subjects receiving DBT were half as likely to make a suicide attempt (hazard ratio, 2.66; P = .005), required less hospitalization for suicide ideation (F 1,92 =7.3; P = .004), and had lower medical risk (F 1,50 =3.2; P = .04) across all suicide attempts and self-injurious acts combined. Subjects receiving DBT were less likely to drop out of treatment (hazard ratio, 3.2; P 1,92 =6.0; P = .007) and psychiatric emergency department visits (F 1,92 =2.9; P = .04). Conclusions Our findings replicate those of previous studies of DBT and suggest that the effectiveness of DBT cannot reasonably be attributed to general factors associated with expert psychotherapy. Dialectical behavior therapy appears to be uniquely effective in reducing suicide attempts.

Insights into social insects from the genome of the honeybee Apis mellifera

Abstract: Here we report the genome sequence of the honeybee Apis mellifera, a key model for social behaviour and essential to global ecology through pollination. Compared with other sequenced insect genomes, the A. mellifera genome has high A+T and CpG contents, lacks major transposon families, evolves more slowly, and is more similar to vertebrates for circadian rhythm, RNA interference and DNA methylation genes, among others. Furthermore, A. mellifera has fewer genes for innate immunity, detoxification enzymes, cuticle-forming proteins and gustatory receptors, more genes for odorant receptors, and novel genes for nectar and pollen utilization, consistent with its ecology and social organization. Compared to Drosophila, genes in early developmental pathways differ in Apis, whereas similarities exist for functions that differ markedly, such as sex determination, brain function and behaviour. Population genetics suggests a novel African origin for the species A. mellifera and insights into whether Africanized bees spread throughout the New World via hybridization or displacement.

Heart Rate Variability as an Index of Regulated Emotional Responding

Abstract: The study of individual differences in emotional responding can provide considerable insight into interpersonal dynamics and the etiology of psychopathology. Heart rate variability (HRV) analysis is emerging as an objective measure of regulated emotional responding (generating emotional responses of appropriate timing and magnitude). This review provides a theoretical and empirical rationale for the use of HRV as an index of individual differences in regulated emotional responding. Two major theoretical frameworks that articulate the role of HRV in emotional responding are presented, and relevant empirical literature is reviewed. The case is made that HRV is an accessible research tool that can increase the understanding of emotion in social and psychopathological processes.

The James Webb Space Telescope

Abstract: The James Webb Space Telescope (JWST) is a large (6.6 m), cold (<50 K), infrared (IR)-optimized space observatory that will be launched early in the next decade into orbit around the second Earth–Sun Lagrange point. The observatory will have four instruments: a near-IR camera, a near-IR multiobject spectrograph, and a tunable filter imager will cover the wavelength range, 0.6 < ; < 5.0 μ m, while the mid-IR instrument will do both imaging and spectroscopy from 5.0 < ; < 29 μ m. The JWST science goals are divided into four themes. The key objective of The End of the Dark Ages: First Light and Reionization theme is to identify the first luminous sources to form and to determine the ionization history of the early universe. The key objective of The Assembly of Galaxies theme is to determine how galaxies and the dark matter, gas, stars, metals, morphological structures, and active nuclei within them evolved from the epoch of reionization to the present day. The key objective of The Birth of Stars and Protoplanetary Systems theme is to unravel the birth and early evolution of stars, from infall on to dust-enshrouded protostars to the genesis of planetary systems. The key objective of the Planetary Systems and the Origins of Life theme is to determine the physical and chemical properties of planetary systems including our own, and investigate the potential for the origins of life in those systems. Within these themes and objectives, we have derived representative astronomical observations. To enable these observations, JWST consists of a telescope, an instrument package, a spacecraft, and a sunshield. The telescope consists of 18 beryllium segments, some of which are deployed. The segments will be brought into optical alignment on-orbit through a process of periodic wavefront sensing and control. The instrument package contains the four science instruments and a fine guidance sensor. The spacecraft provides pointing, orbit maintenance, and communications. The sunshield provides passive thermal control. The JWST operations plan is based on that used for previous space observatories, and the majority of JWST observing time will be allocated to the international astronomical community through annual peer-reviewed proposal opportunities.

Electron transport in molecular junctions.

Abstract: Building an electronic device using individual molecules is one of the ultimate goals in nanotechnology. To achieve this it will be necessary to measure, control and understand electron transport through molecules attached to electrodes. Substantial progress has been made over the past decade and we present here an overview of some of the recent advances. Topics covered include molecular wires, two-terminal switches and diodes, three-terminal transistor-like devices and hybrid devices that use various different signals (light, magnetic fields, and chemical and mechanical signals) to control electron transport in molecules. We also discuss further issues, including molecule-electrode contacts, local heating- and current-induced instabilities, stochastic fluctuations and the development of characterization tools.

TimeTree: a public knowledge-base of divergence times among organisms

Abstract: Summary: Biologists and other scientists routinely need to know times of divergence between species and to construct phylogenies calibrated to time (timetrees). Published studies reporting time estimates from molecular data have been increasing rapidly, but the data have been largely inaccessible to the greater community of scientists because of their complexity. TimeTree brings these data together in a consistent format and uses a hierarchical structure, corresponding to the tree of life, to maximize their utility. Results are presented and summarized, allowing users to quickly determine the range and robustness of time estimates and the degree of consensus from the published literature. Availability: TimeTree is available at http://www.timetree.net Contact: [email protected]

Procedural modeling of buildings

Abstract: CGA shape, a novel shape grammar for the procedural modeling of CG architecture, produces building shells with high visual quality and geometric detail. It produces extensive architectural models for computer games and movies, at low cost. Context sensitive shape rules allow the user to specify interactions between the entities of the hierarchical shape descriptions. Selected examples demonstrate solutions to previously unsolved modeling problems, especially to consistent mass modeling with volumetric shapes of arbitrary orientation. CGA shape is shown to efficiently generate massive urban models with unprecedented level of detail, with the virtual rebuilding of the archaeological site of Pompeii as a case in point.

From patterns to emerging processes in mechanistic urban ecology.

Abstract: Rapid urbanization has become an area of crucial concern in conservation owing to the radical changes in habitat structure and loss of species engendered by urban and suburban development. Here, we draw on recent mechanistic ecological studies to argue that, in addition to altered habitat structure, three major processes contribute to the patterns of reduced species diversity and elevated abundance of many species in urban environments. These activities, in turn, lead to changes in animal behavior, morphology and genetics, as well as in selection pressures on animals and plants. Thus, the key to understanding urban patterns is to balance studying processes at the individual level with an integrated examination of environmental forces at the ecosystem scale.

Determinants of individual engagement in knowledge sharing.

Abstract: Knowledge management systems try to elicit and support the flow of ideas and experiences among groups of employees (sometimes referred to as knowledge communities). Whereas numerous information and communication systems have been developed to support such knowledge exchanges, practical applications have found that technology alone cannot ensure that knowledge will indeed be volunteered and exchanged, and whereas researchers and consultants alike have argued that culture and other human variables constitute key success factors, it is not clear what specific variables are at play, nor what management practices can affect those variables. This exploratory research investigates some of the psychological, organizational and system-related variables that may determine individual engagement in intra-organizational knowledge sharing. Results from a survey of 372 employees from a large multinational show that self-efficacy, openness to experience, perceived support from colleagues and supervisors and, to a lesser ...

Accounting Quality and Debt Contracting

Abstract: We study the role of borrower accounting quality in debt contracting. Specifically, we examine how accounting quality affects the borrower's choice of private versus public debt market and how the design of debt contracts vary with accounting quality in the two markets. We find that accounting quality affects the choice of the market, with poorer accounting quality borrowers preferring private debt (bank loans). This is consistent with banks possessing superior information access and processing abilities which reduce adverse selection costs for borrowers. We also find that accounting quality has an economically significant but differential impact on contract design in the two markets consistent with differences in recontracting flexibility across the two markets. For private debt (which has greater recontracting flexibility), both the price (interest) and non-price (maturity and collateral) terms are significantly more stringent for poorer accounting quality borrowers, unlike public debt where only the price terms are more stringent. The impact of accounting quality on interest spreads of public debt is 2.5 times that of the private debt, since the price terms alone reflect the variation in accounting quality. Overall, the results are consistent with greater recontracting flexibility of banks enabling them to write more customized contracts relative to dispersed bondholders.

Comet 81P/Wild 2 under a microscope.

Abstract: The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study. The preliminary examination of these samples shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin. The comet contains an abundance of silicate grains that are much larger than predictions of interstellar grain models, and many of these are high-temperature minerals that appear to have formed in the inner regions of the solar nebula. Their presence in a comet proves that the formation of the solar system included mixing on the grandest scales.

Association of Usual Sleep Duration With Hypertension: The Sleep Heart Health Study

Abstract: Study Objectives: Limited experimental data suggest that sleep restriction acutely elevates blood pressure; however, little is known about the relationship between usual sleep duration and hypertension. This study assesses the relationship between usual sleep duration and hypertension in a community-based cohort. Design: Cross-sectional observational study. Setting: The Sleep Heart Health Study, a community-based prospective study of the cardiovascular consequences of sleep-disordered breathing. Participants: Two thousand eight hundred thirteen men and 3097 women, aged 40 to 100 years. Interventions: None. Measurements and Results: Usual weekday and weekend sleep durations were obtained by questionnaire, and their weighted average were categorized as less than 6, 6 to less than 7, 7 to less than 8, 8 to less than 9, and 9 or more hours per night. Hypertension was defined as a systolic blood pressure of 140 mm Hg or greater, a diastolic blood pressure of 90 mm Hg or greater, or use of medication to treat hypertension. The relationship between sleep duration and hypertension was examined using categorical logistic regression with adjustment for age, sex, race, apnea-hypopnea index, and body mass index. Compared to subjects sleeping 7 to less than 8 hours per night, those sleeping less than 6 and between 6 and 7 hours per night had adjusted odds ratios for hypertension of 1.66 (95% confidence interval 1.35-2.04) and 1.19 (1.02-1.39), respectively, whereas those sleeping between 8 and 9 and 9 or more hours per night had adjusted odds ratios for hypertension of 1.19 (1.04-1.37) and 1.30 (1.04-1.62), respectively (p <.0001 for association of sleep duration with hypertension). These associations persisted when analyses were further adjusted for caffeine and alcohol consumption, current smoking, insomnia symptoms, depression symptoms, sleep efficiency, and prevalent diabetes mellitus or cardiovascular disease. Conclusions: Usual sleep duration above or below the median of 7 to less than 8 hours per night is associated with an increased prevalence of hypertension, particularly at the extreme of less than 6 hours per night.

A Comparison of Bifactor and Second-Order Models of Quality of Life.

Abstract: Bifactor and second-order factor models are two alternative approaches for representing general constructs comprised of several highly related domains. Bifactor and second-order models were compared using a quality of life data set (N = 403). The bifactor model identified three, rather than the hypothesized four, domain specific factors beyond the general factor. The bifactor model fit the data significantly better than the second-order model. The bifactor model allowed for easier interpretation of the relationship between the domain specific factors and external variables, over and above the general factor. Contrary to the literature, sufficient power existed to distinguish between bifactor and corresponding second-order models in one actual and one simulated example, given reasonable sample sizes. Advantages of bifactor models over second-order models are discussed.

In the Eye of the Beholder: Cross Cultural Lessons in Leadership from Project GLOBE

Abstract: Executive Overview Global leadership has been identified as a critical success factor for large multinational corporations. While there is much writing on the topic, most seems to be either general advice (i.e., being open minded and respectful of other cultures) or very specific information about a particular country based on a limited case study (do not show the soles of your shoes when seated as a guest in an Arab country). Both kinds of information are certainly useful, but limited from both theoretical and practical viewpoints on how to lead in a foreign country. In this paper, findings from the Global Leadership and Organizational Behavior Effectiveness (GLOBE) research program are used to provide a sound basis for conceptualizing worldwide leadership differences. We use a hypothetical case of an American executive in charge of four similar teams in Brazil, France, Egypt, and China to discuss cultural implications for the American executive. Using the hypothetical case involving five different count...

New Generation of Predictive Technology Model for Sub-45 nm Early Design Exploration

Abstract: A predictive MOSFET model is critical for early circuit design research. To accurately predict the characteristics of nanoscale CMOS, emerging physical effects, such as process variations and correlations among model parameters, must be included. In this paper, a new generation of predictive technology model (PTM) is developed to accomplish this goal. Based on physical models and early-stage silicon data, the PTM of bulk CMOS is successfully generated for 130- to 32-nm technology nodes, with an Leff of as low as 13 nm. The accuracy of PTM predictions is comprehensively verified: The error of I on is below 10% for both n-channel MOS and p-channel MOS. By tuning only ten primary parameters, the PTM can be easily customized to cover a wide range of process uncertainties. Furthermore, the new PTM correctly captures process sensitivities in the nanometer regime, particularly the interactions among Leff, Vth, mobility, and saturation velocity. A website has been established for the release of PTM: http://www.eas.asu.edu/~ptm

Peer exclusion and victimization: Processes that mediate the relation between peer group rejection and children's classroom engagement and achievement?

Abstract: Longitudinal data from a study of kindergarten through 5th graders were used to estimate a structural model in which chronic peer exclusion and chronic peer abuse were hypothesized to mediate the link between children's early peer rejection, later classroom engagement, and achievement. Peer exclusion and abuse were expected to predict changes in 2 forms of school engagement (classroom participation and school avoidance), and changes in both forms of engagement were expected to predict changes in achievement. The model fit the data well and lent support to the premise that distinct forms of peer maltreatment and classroom engagement mediate the link between early peer rejection and changes in children's achievement. Early peer rejection was associated with declining classroom participation and increasing school avoidance, but different forms of chronic peer maltreatment mediated these relations. Whereas chronic peer exclusion principally mediated the link between peer rejection and classroom participation, chronic peer abuse primarily mediated the link between rejection and school avoidance. Children's reduced classroom participation, more than gains in school avoidance, anteceded decrements in children's achievement.

Thermal Interface Materials: Historical Perspective, Status, and Future Directions

Abstract: With the continual increase in cooling demand for microprocessors, there has been an increased focus within the microelectronics industry on developing thermal solutions. Thermal interface materials (TIMs) play a key role in thermally connecting various components of the thermal solution. Review of the progress made in the area of TIMs in the past five years is presented. The focus is on the rheology-based modeling and design of polymeric TIMs due to their widespread use. Review of limited literature on the thermal performance of solders is also provided. Merits and demerits of using nanoparticles and nanotubes for TIM applications are also discussed. I conclude the paper with some directions for the future that I feel are relatively untouched and potentially very beneficial

Conceptualizing and measuring cultures and their consequences: a comparative review of GLOBE's and Hofstede's approaches

Abstract: This paper explains why GLOBE used a set of cultural values and practices to measure national cultures. We show why there is no theoretical or empirical basis for Hofstede's criticism that GLOBE measures of values are too abstract or for his contention that national and organizational cultures are phenomena of different order. We also show why Hofstede has a limited understanding of the relationship between national wealth and culture. Furthermore, we explain why Hofstede's reanalysis of the GLOBE data is inappropriate and produces incomprehensible results. We also show the validity of managerial samples in studying leadership. Finally, we explain why Hofstede's claim that GLOBE instruments reflect researchers psycho-logic reveals ignorance of psychometric methodologies designed to ensure scale reliability and construct validity.

The globalization of socio-ecological systems: An agenda for scientific research

Abstract: We argue that globalization is a central feature of coupled human–environment systems or, as we call them, socio-ecological systems (SESs). In this article, we focus on the effects of globalization on the resilience, vulnerability, and adaptability of these systems. We begin with a brief discussion of key terms, arguing that socio-economic resilience regularly substitutes for biophysical resilience in SESs with consequences that are often unforeseen. A discussion of several mega-trends (e.g. the rise of mega-cities, the demand for hydrocarbons, the revolution in information technologies) underpins our argument. We then proceed to identify key analytical dimensions of globalization, including rising connectedness, increased speed, spatial stretching, and declining diversity. We show how each of these phenomena can cut both ways in terms of impacts on the resilience and vulnerability of SESs. A particularly important insight flowing from this analysis centers on the reversal of the usual conditions in which large-scale things are slow and durable while small-scale things are fast and ephemeral. The fact that SESs are reflexive can lead either to initiatives aimed at avoiding or mitigating the dangers of globalization or to positive feedback processes that intensify the impacts of globalization. In the concluding section, we argue for sustained empirical research regarding these concerns and make suggestions about ways to enhance the incentives for individual researchers to work on these matters.

SME internationalization research: past, present, and future

Abstract: Purpose – The purpose of this paper is to understand the similarities and differences in the internationalization of SMEs and MNEs and the specific factors affecting them.Design/methodology/approach – The relevant literature was reviewed particularly in the context of the major theories of internationalization.Findings – The positive and negative aspects of each theoretical approach to internationalization are present to form the basis of a new model of international entrepreneurship.Research limitations/implications – The newly developed conceptual model has not been empirically tested.Originality/value – A redeveloped theoretical integrative conceptual model of international entrepreneurship is proposed based on four internationalization properties (mode, market, product, and time), internationalization performance, and key antecedents and consequences of the internationalization process.

Managing social norms for persuasive impact

Abstract: In order to mobilise action against a social problem, public service communicators often include normative information in their persuasive appeals. Such messages can be either effective or ineffective because they can normalise either desirable or undesirable conduct. To examine the implications in an environmental context, visitors to Arizona’s Petrified Forest National Park were exposed to messages that admonished against the theft of petrified wood. In addition, the messages conveyed information either about descriptive norms (the levels of others’ behaviour) or injunctive norms (the levels of others’ disapproval) regarding such thievery. Results showed that focusing message recipients on descriptive normative information was most likely to increase theft, whereas focusing them on injunctive normative information was most likely to suppress it. Recommendations are offered for optimising the impact of normative messages in situations characterised by objectionable levels of undesirable conduct.