Showing papers by "Arizona State University published in 1999"

Design and synthesis of an exceptionally stable and highly porous metal-organic framework

Abstract: Open metal–organic frameworks are widely regarded as promising materials for applications1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 in catalysis, separation, gas storage and molecular recognition. Compared to conventionally used microporous inorganic materials such as zeolites, these organic structures have the potential for more flexible rational design, through control of the architecture and functionalization of the pores. So far, the inability of these open frameworks to support permanent porosity and to avoid collapsing in the absence of guest molecules, such as solvents, has hindered further progress in the field14,15. Here we report the synthesis of a metal–organic framework which remains crystalline, as evidenced by X-ray single-crystal analyses, and stable when fully desolvated and when heated up to 300?°C. This synthesis is achieved by borrowing ideas from metal carboxylate cluster chemistry, where an organic dicarboxylate linker is used in a reaction that gives supertetrahedron clusters when capped with monocarboxylates. The rigid and divergent character of the added linker allows the articulation of the clusters into a three-dimensional framework resulting in a structure with higher apparent surface area and pore volume than most porous crystalline zeolites. This simple and potentially universal design strategy is currently being pursued in the synthesis of new phases and composites, and for gas-storage applications.

Statistical Methods for Reliability Data

Abstract: Statistical Methods For Reliability Data Statistical Methods for Reliability Data updates and improves established techniques as it demonstrates how to apply the new graphical, numerical, or simulation-based methods to a broad range of models encountered in reliability data analysis. It includes methods for planning reliability studies and analyzing degradation data, simulation methods used to complement large-sample asymptotic theory, general likelihood-based methods of handling arbitrarily censored data and

How can you do it?: Dirty work and the challenge of constructing a positive identity

Abstract: The identity literature suggests that the stigma of “dirty work” threatens the ability of occupational members to construct an esteem-enhancing social identity. However, research indicates much the opposite, creating a puzzle we attempt to answer. We argue that the stigma of dirty work fosters development of a strong occupational or workgroup culture, which fosters (1) ideological reframing, recalibrating, and refocusing and (2) selective social comparisons and differential weighting of outsiders' views. These defense mechanisms transform the meaning of “dirt” and moderate the impact of social perceptions of dirtiness.

Perspective: highly variable loci and their interpretation in evolution and conservation.

Abstract: Although highly variable loci, such as microsatellite loci, are revolutionizing both evolutionary and conservation biology, data from these loci need to be carefully evaluated. First, because these loci often have very high within-population heterozygosity, the magnitude of differentiation measures may be quite small. For example, maximum GST values for populations with no common alleles at highly variable loci may be small and are at maximum less than the average within-population homozygosity. As a result, measures that are variation independent are recommended for highly variable loci. Second, bottlenecks or a reduction in population size can generate large genetic distances in a short time for these loci. In this case, the genetic distance may be corrected for low variation in a population and tests to detect bottlenecks are advised. Third, statistically significant differences may not reflect biologically meaningful differences both because the patterns of adaptive loci may not be correlated with highly variable loci and statistical power with these markers is so high. As an example of this latter effect, the statistical power to detect a one-generation bottleneck of different sizes for different numbers of highly variable loci is discussed. All of these concerns need to be incorporated in the utilization and interpretation of patterns of highly variable loci for both evolutionary and conservation biology.

Competence in the context of adversity: pathways to resilience and maladaptation from childhood to late adolescence.

Abstract: Competent outcomes in late adolescence were examined in relation to adversity over time, antecedent competence and psychosocial resources, in order to investigate the phenomenon of resilience. An urban community sample of 205 (114 females, 90 males; 27% minority) children were recruited in elementary school and followed over 10 years. Multiple methods and informants were utilized to assess three major domains of competence from childhood through adolescence (academic achievement, conduct, and peer social competence), multiple aspects of adversity, and major psychosocial resources. Both variable-centered and person-centered analyses were conducted to test the hypothesized significance of resources for resilience. Better intellectual functioning and parenting resources were associated with good outcomes across competence domains, even in the context of severe, chronic adversity. IQ and parenting appeared to have a specific protective role with respect to antisocial behavior. Resilient adolescents (high adversity, adequate competence across three domains) had much in common with their low-adversity competent peers, including average or better IQ, parenting, and psychological well-being. Resilient individuals differed markedly from their high adversity, maladaptive peers who had few resources and high negative emotionality. Results suggest that IQ and parenting scores are markers of fundamental adaptational systems that protect child development in the context of severe adversity.

Analyzing the commitment-loyalty link in service contexts

Abstract: This study addressed the ill-understood issue of how loyalty develops in service patrons. Although many theorists hold commitment to be an essential part of this process, the link between commitment and loyalty has received little empirical attention. To address this void, the study first portrayed commitment’s root tendency to resist changing preference as a function of three antecedent processes. Second, this portrayal formed the basis for developing a psychometrically sound scale to measure the construct of commitment. Third, the scale was then used in a mediating effects model (M-E-M) to test the commitment-loyalty link. Path analyses found this parsimonious structure to be a significant improvement over rival direct effects models (D-E-Ms). Results found the tendency to resist changing preference to be a key precursor to loyalty, largely explained by a patron’s willingness to identify with a brand. Implications of these findings for loyalty’s development and research are explored.

From Condensed Lanthanide Coordination Solids to Microporous Frameworks Having Accessible Metal Sites

Abstract: The combination of terbium nitrate and 1,4-benzenedicarboxylic acid (H2BDC) in the presence of triethylamine yields the compound Tb2(BDC)3·(H2O)4, which has an extended nonporous structure constructed from copolymerized BDC and Tb(III) units. The multidentate functionality of BDC and the tendency of Tb to have a high coordination number has allowed water to act as a terminal ligand to Tb in the structure. Upon thermally liberating the water ligands, a microporous material, Tb2(BDC)3, is achieved, which has extended 1-D channels and the same framework structure as that of the as-synthesized solid as evidenced by XRPD. Water sorption isotherm data proves that Tb2(BDC)3 has permanent microporosity, and points to the presence of accessible metal sites within the pores, which also allows the sorption of ammonia to give Tb2(BDC)3·(NH3)4. Luminescence lifetime measurements confirm that resorbed water and sorbed ammonia are bound to Tb and that they give distinctly different decay constants.

Seismic Consequences of Warm Versus Cool Subduction Metamorphism: Examples from Southwest and Northeast Japan

Abstract: Warm and cool subduction zones exhibit differences in seismicity, seismic structure, and arc magmatism, which reflect differences in metamorphic reactions occurring in subducting oceanic crust. In southwest Japan, arc volcanism is sparse and intraslab earthquakes extend to 65 kilometers depth; in northeast Japan, arc volcanism is more common and intraslab earthquakes reach 200 kilometers depth. Thermal-petrologic models predict that oceanic crust subducting beneath southwest Japan is 300° to 500°C warmer than beneath northeast Japan, resulting in shallower eclogite transformation and slab dehydration reactions, and possible slab melting.

Tailored Porous Materials

Abstract: Tailoring of porous materials involves not only chemical synthetic techniques for tailoring microscopic properties such as pore size, pore shape, pore connectivity, and pore surface reactivity, but also materials processing techniques for tailoring the meso- and the macroscopic properties of bulk materials in the form of fibers, thin films, and monoliths. These issues are addressed in the context of five specific classes of porous materials: oxide molecular sieves, porous coordination solids, porous carbons, sol−gel-derived oxides, and porous heteropolyanion salts. Reviews of these specific areas are preceded by a presentation of background material and review of current theoretical approaches to adsorption phenomena. A concluding section outlines current research needs and opportunities.

An Empirical Examination of the Form of the Relationship Between Multinationality and Performance

Abstract: This paper reports findings from a study that systematically evaluated the form of the relationship between multinationality and performance. In contrast to most of the prior conceptualizations that rely on linear, monotonic models of the linkage, this study examined a curvilinear model that addresses both the costs and benefits associated with multinationality. It used time-series techniques to capture both the static and dynamic components of the relationship. Results show that increasing levels of multinationality bring significant performance benefits up to a certain optimum level beyond which benefits begin to decelerate, while costs accelerate.

Thermodynamic determination of fragility in liquids and a fragile-to-strong liquid transition in water

Abstract: If crystallization can be avoided when a liquid is cooled, it will typically form a glass. Near the glass transition temperature the viscosity increases continuously but rapidly with cooling. As the glass forms, the molecular relaxation time increases with an Arrhenius-like (simple activated) form in some liquids, but shows highly non-Arrhenius behaviour in others. The former are said to be ‘strong’ liquids, and the latter ‘fragile’1,2. Here we show that the fragility of a liquid can be determined from purely thermodynamic data (as opposed to measurements of kinetics) near and below the melting point. We find that for most liquids the fragilities estimated this way are consistent with those obtained by previous methods and by a new method (ref. 3 and K.I., C.A.A. and C.T.M., unpublished data) at temperatures near the glass transition. But water is an exception. The thermodynamic method indicates that near its melting point it is the most fragile of all liquids studied, whereas the kinetic approach indicates that near the glass transition it is the least fragile. We propose that this discrepancy can be explained by a fragile-to-strong transition in supercooled water near 228 K, corresponding to a change in the liquid's structure at this point.

Repeated restraint stress facilitates fear conditioning independently of causing hippocampal CA3 dendritic atrophy.

Abstract: This study investigated whether 21 days of restraint stress (6 hr/day) and the subsequent hippocampal dendritic atrophy would affect fear conditioning, a memory task with hippocampal-dependent and hippocampal-independent components. Restraint-stressed rats were injected daily (21 days) with tianeptine (10 mg/kg; to prevent hippocampal atrophy) or vehicle then tested on fear conditioning (Days 23-25, with 2 tone-shock pairings) and open field (Day 25). Restraint stress enhanced freezing to context (hippocampal-dependent behavior) and tone (hippocampal-independent) and decreased open-field exploration, irrespective of whether tianeptine was given. Results confirmed that stress produced CA3 dendritic atrophy and tianeptine prevented it. Moreover, CA3 dendritic atrophy was not permanent but reversed to control levels by 10 days after the cessation of restraint stress. These data argue that different neural substrates underlie spatial recognition memory and fear conditioning.

Research Issues and Ideas in Statistical Process Control

Abstract: An overview is given of current research on control charting methods for process monitoring and improvement. A historical perspective and ideas for future research also are given. Research topics include: variable sample size and sampling interval met..

The stoichiometry of consumer-driven nutrient recycling: theory, observations, and consequences

Abstract: Ecologists are increasingly recognizing the importance of consumers in reg- ulating ecosystem processes such as nutrient cycling. Ecologists have recently made con- siderable progress in understanding nutrient cycling and trophic interactions in pelagic systems by application of a new concept, ecological stoichiometry, to consumer-driven processes. In this paper we synthesize these conceptual advances within pelagic ecology and attempt to illustrate how they may be usefully applied in other ecosystems. Stoichi- ometric theory shows that both grazer and algal elemental composition are critical param- eters influencing rates and ratios of nutrient release. Thus, the stoichiometry of nutrient recycling is a feedback mechanism linking grazer dynamics and algal nutritional status. Incorporation of such effects into a fully dynamic stoichiometric model generates profound changes in the predicted dynamics of algae and grazers, suggesting that adoption of a stoichiometric view may substantively alter our view of the interaction between trophic dynamics and nutrient cycling. The basic predictions of stoichiometric models of nutrient release are generally supported by experimental data showing that N:P release ratios are primarily a function of algal N:P ratio and secondarily a function of grazer N:P ratio, and that rates of P release by grazers are also related to food P:C. Furthermore, evidence for effects of nutrient release stoichiometry on phytoplankton communities and pelagic eco- system function is accumulating, including data showing consistent alterations in algal physiological status and ecosystem-scale changes in N fixation in response to altered grazer community structure and elemental composition. As the general features of the stoichi- ometry of algae-zooplankton interactions reflect fundamental biological processes linked to plant and animal mineral nutrition, the stoichiometric view of consumer-driven nutrient recycling can easily be applied to other ecosystems, including terrestrial and benthic food webs. A suite of potential applications of stoichiometric thinking to benthic and terrestrial habitats is suggested.

How Habitat Edges Change Species Interactions

Abstract: Traditionally, ecologists interested in habitat edges have focused on edge‐related gradients in patterns of species richness or abiotic variables. Here, however, we take a different perspective, attempting to synthesize recent empirical results concerning the effects of habitat edges on population dynamics with contemporary theoretical developments to outline the ways in which species interactions, and the dynamics of the communities in which they are embedded, can be changed by habitat edges. We find a striking convergence between empirical notions of a patch's core area and analytical results from partial differential equation models. A review of both empirical and theoretical studies suggests four general classes of mechanisms through which habitat edges can have similar impacts on dissimilar types of species interactions. Specifically, we focus on edges' roles as dispersal barriers or filters, edges' influences on mortality, edges' involvement in spatial subsidies (in which dispersers' intra...

The Effect of Parental Transfers and Borrowing Constraints OnEducational Attainment

Abstract: A strong positive association between one's school attainment and that of one's parents has been consistently documented in numerous empirical studies. The underlying cause of this intergenerational correlation has been the subject of contentious debate in the social sciences for many years. Two competing types of explanations are prominent. The first is based on the heritability of traits, that is, that children of more educated parents may inherit the abilities, personalities and preferences that led to the higher educational achievement of their parents. The second type of explanation is based on human capital production, namely that more educated parents, due to their own preferences for more educated children and/or due to their higher wealth, may invest more heavily in their children's human capital.

Ceo Charismatic Leadership: Levels-of-Management and Levels-of-Analysis Effects

Abstract: We present a model of CEO charismatic leadership in organizations and show how such leadership can, through levels of management and analysis, impact organizational performance. We integrate levels issues relevant to the conceptualization of theoretical constructs and their relationships, measurement, and echelons, and develop the concept of close versus distant leadership as a means of understanding the dynamics of CEO leadership. We also include a consideration of possible alternative levels of analysis at which the constructs in our model may be operating.

Prejudice toward immigrants

Abstract: In the present study, 4 variables (realistic threats, symbolic threats, intergroup ankiety. and negative stereotypes) were used to predict prejudice toward immigrants from Cuba, Mesico. and Asia in samples of students from states in the United States that are affected h) immigration from these areas (Florida, New Mexico, and Hawaii. respectively). All 4 variables were significant (or marginally significant) predictors of attitudes toward these immigrant groups. Evidence is presented that the predictor variables are conceptually and empirically distinct. However, these variables do appear to be tied together by an underlying theme: They all concern threats to the in-group or its members. Some of the implications of the results for intergroup relations are discussed.

Parental reactions to children's negative emotions: longitudinal relations to quality of children's social functioning.

Abstract: Relations between self-reported parental reactions to children's negative emotions (PNRs) and children's socially appropriate/problem behavior and negative emotionality were examined longitudinally. Evidence was consistent with the conclusion that relations between children's externalizing (but not internalizing) emotion and parental punitive reactions to children's negative emotions are bidirectional. Reports of PNRs generally were correlated with low quality of social functioning. In structural models, mother-reported problem behavior at ages 10-12 was at least marginally predicted from mother-reported problem behavior, children's regulation, and parental punitive or distress reactions. Moreover, parental distress and punitive reactions at ages 6-8 predicted reports of children's regulation at ages 8-10, and regulation predicted parental punitive reactions at ages 10-12. Father reports of problem behavior at ages 10-12 were predicted by earlier problem behavior and parental distress or punitive reactions; some of the relations between regulation and parental reactions were similar to those in the models for mother-reported problem behavior. Parental perceptions of their reactions were substantially correlated over 6 years. Some nonsupportive reactions declined in the early to mid-school years, but all increased into late childhood/early adolescence.

Accessing Nearby Copies of Replicated Objects in a Distributed Environment

Abstract: Consider a set of shared objects in a distributed network, where several copies of each object may exist at any given time. To ensure both fast access to the objects as well as efficient utilization of network resources, it is desirable that each access request be satisfied by a copy ``close'' to the requesting node. Unfortunately, it is not clear how to achieve this goal efficiently in a dynamic, distributed environment in which large numbers of objects are continuously being created, replicated, and destroyed. In this paper we design a simple randomized algorithm for accessing shared objects that tends to satisfy each access request with a nearby copy. The algorithm is based on a novel mechanism to maintain and distribute information about object locations, and requires only a small amount of additional memory at each node. We analyze our access scheme for a class of cost functions that captures the hierarchical nature of wide-area networks. We show that under the particular cost model considered (i) the expected cost of an individual access is asymptotically optimal, and (ii) if objects are sufficiently large, the memory used for objects dominates the additional memory used by our algorithm with high probability. We also address dynamic changes in both the network and the set of object copies.

Tourism in Crisis: Managing the Effects of Terrorism

Abstract: While tourists are free to avoid destinations associated with risk, the consequences of disastrous events on tourist destinations are inescapable and can be profound. Terrorism that targets tourism can be viewed as a disaster for a destination and ensuing events can create a serious tourism crisis. This article argues that tourist destinations—especially those vulnerable to politically motivated violence—should incorporate crisis management planning into their overall sustainable development and marketing/management strategies to protect and rebuild their image of safety/attractiveness, to reassure potential visitors of the safety of the area, to reestablish the area’s functionality/attractiveness, and to aid local travel and tourism industry members in their economic recovery. Recommendations include having a crisis management plan in place, establishing a tourism crisis management task force, developing a crisis management guidebook, and partnering with law enforcement officials.

Islamic Ethics and the Implications for Business

Abstract: As global business operations expand, managers need more knowledge of foreign cultures, in particular, information on the ethics of doing business across borders. The purpose of this paper is twofold: (1) to share the Islamic perspective on business ethics, little known in the west, which may stimulate further thinking and debate on the relationships between ethics and business, and (2) to provide some knowledge of Islamic philosophy in order to help managers do business in Muslim cultures. The case of Egypt illustrates some divergence between Islamic philosophy and practice in economic life. The paper concludes with managerial implications and suggestions for further research.

Motivation for Achievement in Mathematics: Findings, Generalizations, and Criticisms of the Research

Abstract: In this review we examine recent research in the area of motivation in mathematics education and discuss findings from research perspectives in this domain. We note consistencies across research perspectives that suggest a set of generalizable conclusions about the contextual factors, cognitive processes, and benefits of interventions that affect students’ and teachers’ motivational attitudes. Criticisms are leveled concerning the lack of theoretical guidance driving the conduct and interpretation of the majority of studies in the field. Few researchers have attempted to extend current theories of motivation in ways that are consistent with the current research on learning and classroom discourse. In particular, researchers interested in studying motivation in the content domain of school mathematics need to examine the relationship that exists between mathematics as a socially constructed field and students’ desire to achieve.

Lifestyle of the Tight and Frugal: Theory and Measurement

Abstract: Who has not known a tightwad? Yet this pervasive consumer trait—being frugal—has been ignored in the scholarly consumer behavior literature This research articulates the nature of this overlooked consumer trait and then develops, evaluates, and empirically applies a multi-item scale of frugality The results from a six-study program of empirical research are reported These studies describe (1) the psychometric properties of a frugality measure, (2) demonstrations of how frugality assists the empirical study of consumer usage and acquisition behaviors, and (3) frugality scale norms from a probability sample of the general adult population

Implementing Marketing Strategies: Developing and Testing a Managerial Theory

Abstract: Implementation pervades strategic performance. It is a critical link between the formulation of marketing strategies and the achievement of superior organizational performance. Research conducted i...