Showing papers by "Ohio State University published in 2002"

On the Practice of Dichotomization of Quantitative Variables

Abstract: The authors examine the practice of dichotomization of quantitative measures, wherein relationships among variables are examined after 1 or more variables have been converted to dichotomous variables by splitting the sample at some point on the scale(s) of measurement. A common form of dichotomization is the median split, where the independent variable is split at the median to form high and low groups, which are then compared with respect to their means on the dependent variable. The consequences of dichotomization for measurement and statistical analyses are illustrated and discussed. The use of dichotomization in practice is described, and justifications that are offered for such usage are examined. The authors present the case that dichotomization is rarely defensible and often will yield misleading results. We consider here some simple statistical procedures for studying relationships of one or more independent variables to one dependent variable, where all variables are quantitative in nature and are measured on meaningful numerical scales. Such measures are often referred to as individual-differences measures, meaning that observed values of such measures are interpretable as reflecting individual differences on the attribute of interest. It is of course straightforward to analyze such data using correlational methods. In the case of a single independent variable, one can use simple linear regression and/or obtain a simple correlation coefficient. In the case of multiple independent variables, one can use multiple regression, possibly including interaction terms. Such methods are routinely used in practice. However, another approach to analysis of such data is also rather widely used. Considering the case of one independent variable, many investigators begin by converting that variable into a dichotomous variable by splitting the scale at some point and designating individuals above and below that point as defining

Biomimicry of bacterial foraging for distributed optimization and control

Abstract: We explain the biology and physics underlying the chemotactic (foraging) behavior of E. coli bacteria. We explain a variety of bacterial swarming and social foraging behaviors and discuss the control system on the E. coli that dictates how foraging should proceed. Next, a computer program that emulates the distributed optimization process represented by the activity of social bacterial foraging is presented. To illustrate its operation, we apply it to a simple multiple-extremum function minimization problem and briefly discuss its relationship to some existing optimization algorithms. The article closes with a brief discussion on the potential uses of biomimicry of social foraging to develop adaptive controllers and cooperative control strategies for autonomous vehicles. For this, we provide some basic ideas and invite the reader to explore the concepts further.

Sloan digital sky survey: Early data release

Abstract: The Sloan Digital Sky Survey (SDSS) is an imaging and spectroscopic survey that will eventually cover approximately one-quarter of the celestial sphere and collect spectra of ≈106 galaxies, 100,000 quasars, 30,000 stars, and 30,000 serendipity targets. In 2001 June, the SDSS released to the general astronomical community its early data release, roughly 462 deg2 of imaging data including almost 14 million detected objects and 54,008 follow-up spectra. The imaging data were collected in drift-scan mode in five bandpasses (u, g, r, i, and z); our 95% completeness limits for stars are 22.0, 22.2, 22.2, 21.3, and 20.5, respectively. The photometric calibration is reproducible to 5%, 3%, 3%, 3%, and 5%, respectively. The spectra are flux- and wavelength-calibrated, with 4096 pixels from 3800 to 9200 A at R ≈ 1800. We present the means by which these data are distributed to the astronomical community, descriptions of the hardware used to obtain the data, the software used for processing the data, the measured quantities for each observed object, and an overview of the properties of this data set.

A Domain-Specific Risk-Attitude Scale: Measuring Risk Perceptions and Risk Behaviors

Abstract: We present a psychometric scale that assesses risk taking in five content domains: financial decisions (separately for investing versus gambling), health/safety, recreational, ethical, and social decisions. Respondents rate the likelihood that they would engage in domain-specific risky activities (Part I). An optional Part II assesses respondents’ perceptions of the magnitude of the risks and expected benefits of the activities judged in Part I. The scale’s construct validity and consistency is evaluated for a sample of American undergraduate students. As expected, respondents’ degree of risk taking was highly domain-specific, i.e. not consistently risk-averse or consistently risk-seeking across all content domains. Women appeared to be more risk-averse in all domains except social risk. A regression of risk taking (likelihood of engaging in the risky activity) on expected benefits and perceived risks suggests that gender and content domain differences in apparent risk taking are associated with differences in the perception of the activities’ benefits and risk, rather than with differences in attitude towards perceived risk.

Spectroscopic Target Selection in the Sloan Digital Sky Survey: The Main Galaxy Sample

Abstract: We describe the algorithm that selects the main sample of galaxies for spectroscopy in the Sloan Digital Sky Survey (SDSS) from the photometric data obtained by the imaging survey. Galaxy photometric properties are measured using the Petrosian magnitude system, which measures flux in apertures determined by the shape of the surface brightness profile. The metric aperture used is essentially independent of cosmological surface brightness dimming, foreground extinction, sky brightness, and the galaxy central surface brightness. The main galaxy sample consists of galaxies with r-band Petrosian magnitudes r ≤ 17.77 and r-band Petrosian half-light surface brightnesses μ50 ≤ 24.5 mag arcsec-2. These cuts select about 90 galaxy targets per square degree, with a median redshift of 0.104. We carry out a number of tests to show that (1) our star-galaxy separation criterion is effective at eliminating nearly all stellar contamination while removing almost no genuine galaxies, (2) the fraction of galaxies eliminated by our surface brightness cut is very small (~0.1%), (3) the completeness of the sample is high, exceeding 99%, and (4) the reproducibility of target selection based on repeated imaging scans is consistent with the expected random photometric errors. The main cause of incompleteness is blending with saturated stars, which becomes more significant for brighter, larger galaxies. The SDSS spectra are of high enough signal-to-noise ratio (S/N > 4 per pixel) that essentially all targeted galaxies (99.9%) yield a reliable redshift (i.e., with statistical error less than 30 km s-1). About 6% of galaxies that satisfy the selection criteria are not observed because they have a companion closer than the 55'' minimum separation of spectroscopic fibers, but these galaxies can be accounted for in statistical analyses of clustering or galaxy properties. The uniformity and completeness of the galaxy sample make it ideal for studies of large-scale structure and the characteristics of the galaxy population in the local universe.

Spectroscopic Target Selection in the Sloan Digital Sky Survey: The Main Galaxy Sample

Abstract: We describe the algorithm that selects the main sample of galaxies for spectroscopy in the Sloan Digital Sky Survey from the photometric data obtained by the imaging survey. Galaxy photometric properties are measured using the Petrosian magnitude system, which measures flux in apertures determined by the shape of the surface brightness profile. The metric aperture used is essentially independent of cosmological surface brightness dimming, foreground extinction, sky brightness, and the galaxy central surface brightness. The main galaxy sample consists of galaxies with r-band Petrosian magnitude r < 17.77 and r-band Petrosian half-light surface brightness < 24.5 magnitudes per square arcsec. These cuts select about 90 galaxy targets per square degree, with a median redshift of 0.104. We carry out a number of tests to show that (a) our star-galaxy separation criterion is effective at eliminating nearly all stellar contamination while removing almost no genuine galaxies, (b) the fraction of galaxies eliminated by our surface brightness cut is very small (0.1%), (c) the completeness of the sample is high, exceeding 99%, and (d) the reproducibility of target selection based on repeated imaging scans is consistent with the expected random photometric errors. (abridged)

A domain-specific risk-attitude scale: measuring risk perceptions and risk behaviors

Abstract: We present a psychometric scale that assesses risk taking in five content domains: financial decisions (separately for investing versus gambling), health/safety, recreational, ethical, and social decisions. Respondents rate the likelihood that they would engage in domain-specific risky activities (Part I). An optional Part II assesses respondents' perceptions of the magnitude of the risks and expected benefits of the activities judged in Part I. The scale's construct validity and consistency is evaluated for a sample of American undergraduate students. As expected, respondents' degree of risk taking was highly domain-specific, i.e. not consistently risk-averse or consistently risk-seeking across all content domains. Women appeared to be more risk-averse in all domains except social risk. A regression of risk taking (likelihood of engaging in the risky activity) on expected benefits and perceived risks suggests that gender and content domain differences in apparent risk taking are associated with differences in the perception of the activities' benefits and risk, rather than with differences in attitude towards perceived risk. Copyright © 2002 John Wiley & Sons, Ltd.

Introduction to Tribology

Abstract: Foreword. Preface. 1 Introduction. 1.1 De.nition and History of Tribology. 1.2 Industrial Signi.cance of Tribology. 1.3 Origins and Signi.cance of Micro/Nanotribology. 1.4 Organization of the Book. References. 2 Solid Surface Characterization. 2.1 The Nature of Surfaces. 2.2 Physico-Chemical Characteristics of Surface Layers. 2.3 Analysis of Surface Roughness. 2.4 Measurement of Surface Roughness. 2.5 Closure. References. Suggested Reading. 3 Contact between Solid Surfaces. 3.1 Introduction. 3.2 Analysis of the Contacts. 3.3 Measurement of the Real Area of Contact. 3.4 Closure. References. Suggested Reading. 4 Adhesion. 4.1 Introduction. 4.2 Solid-Solid Contact. 4.3 Liquid-Mediated Contact. 4.4 Closure. References. Suggested Reading. 5 Friction. 5.1 Introduction. 5.2 Solid-Solid Contact. 5.3 Liquid-Mediated Contact. 5.4 Friction of Materials. 5.5 Closure. References. Suggested Reading. 6 Interface Temperature of Sliding Surfaces. 6.1 Introduction. 6.2 Thermal Analysis. 6.3 Interface Temperature Measurements. 6.4 Closure. References. 7 Wear. 7.1 Introduction. 7.2 Types of Wear Mechanisms. 7.3 Types of Particles Present in Wear Debris. 7.4 Wear of Materials. 7.5 Closure. References. Suggested Reading. 8 Fluid Film Lubrication. 8.1 Introduction. 8.2 Regimes of Fluid Film Lubrication. 8.3 Viscous Flow and Reynolds Equation. 8.4 Hydrostatic Lubrication. 8.5 Hydrodynamic Lubrication. 8.6 Elastohydrodynamic Lubrication. 8.7 Closure. References. Suggested Reading. 9 Boundary Lubrication and Lubricants. 9.1 Introduction. 9.2 Boundary Lubrication. 9.3 Liquid Lubricants. 9.4 Greases. 9.5 Closure. References. Suggested Reading. 10 Micro/Nanotribology. 10.1 Introduction. 10.2 SFA Studies. 10.3 AFM/FFM. 10.4 Atomic-Scale Simulations. 10.5 Closure. References. Suggested Reading. 11 Friction and Wear Screening Test Methods. 11.1 Introduction. 11.2 Design Methodology. 11.3 Typical Test Geometries. 11.4 Closure. References. Suggested Reading. 12Tribological Components and Applications. 12.1 Introduction. 12.2 Common Tribological Components. 12.3 Microcomponents. 12.4 Material Processing. 12.5 Industrial Applications. 12.6 Closure. References. Suggested Reading. Problems. Appendix Units, Conversions, and Useful Relations. A.1 Fundamental Constants. A.2 Conversion of Units. A.3 Useful Relations. Index.

Hierarchical ID-Based Cryptography

Abstract: We present hierarchical identity-based encryption schemes and signature schemes that have total collusion resistance on an arbitrary number of levels and that have chosen ciphertext security in the random oracle model assuming the difficulty of the Bilinear Diffie-Hellman problem.

Risperidone in Children with Autism and Serious Behavioral Problems

Abstract: Background Atypical antipsychotic agents, which block postsynaptic dopamine and serotonin receptors, have advantages over traditional antipsychotic medications in the treatment of adults with schizophrenia and may be beneficial in children with autistic disorder who have serious behavioral disturbances. However, data on the safety and efficacy of atypical antipsychotic agents in children are limited. Methods We conducted a multisite, randomized, double-blind trial of risperidone as compared with placebo for the treatment of autistic disorder accompanied by severe tantrums, aggression, or self-injurious behavior in children 5 to 17 years old. The primary outcome measures were the score on the Irritability subscale of the Aberrant Behavior Checklist and the rating on the Clinical Global Impressions — Improvement (CGI-I) scale at eight weeks. Results A total of 101 children (82 boys and 19 girls; mean [±SD] age, 8.8±2.7 years) were randomly assigned to receive risperidone (49 children) or placebo (52). Treat...

Social Identity Complexity

Abstract: In this article, we introduce the concept of social identity complexity—a new theoretical construct that refers to an individual’s subjective representation of the interrelationships among his or her multiple group identities. Social identity complexity reflects the degree of overlap perceived to exist between groups of which a person is simultaneously a member. When the overlap of multiple ingroups is perceived to be high, the individual maintains a relatively simplified identity structure whereby memberships in different groups converge to form a single ingroup identification. When a person acknowledges, and accepts, that memberships in multiple ingroups are not fully convergent or overlapping, the associated identity structure is both more inclusive and more complex. In this article, we define the concept of social identity complexity and discuss its possible antecedents and consequences. Results from initial studies support the prediction that social identity complexity is affected by stress and is related to personal value priorities and to tolerance of outgroup members. Recently researchers of group processes have expressed increasing interest in the fact that most individuals are simultaneously members of multiple social groups. Although there has been some research on the

Germ-line mutations in nonsyndromic pheochromocytoma.

Abstract: Background The group of susceptibility genes for pheochromocytoma that included the proto-oncogene RET (associated with multiple endocrine neoplasia type 2 [MEN-2]) and the tumor-suppressor gene VHL (associated with von Hippel–Lindau disease) now also encompasses the newly identified genes for succinate dehydrogenase subunit D (SDHD) and succinate dehydrogenase subunit B (SDHB), which predispose carriers to pheochromocytomas and glomus tumors. We used molecular tools to classify a large cohort of patients with pheochromocytoma with respect to the presence or absence of mutations of one of these four genes and to investigate the relevance of genetic analyses to clinical practice. Methods Peripheral blood from unrelated, consenting registry patients with pheochromocytoma was tested for mutations of RET, VHL, SDHD, and SDHB. Clinical data at first presentation and follow-up were evaluated. Results Among 271 patients who presented with nonsyndromic pheochromocytoma and without a family history of the disease,...

Control of Synaptic Strength by Glial TNFα

Abstract: Activity-dependent modulation of synaptic efficacy in the brain contributes to neural circuit development and experience-dependent plasticity. Although glia are affected by activity and ensheathe synapses, their influence on synaptic strength has largely been ignored. Here, we show that a protein produced by glia, tumor necrosis factor alpha (TNFalpha), enhances synaptic efficacy by increasing surface expression of AMPA receptors. Preventing the actions of endogenous TNFalpha has the opposite effects. Thus, the continual presence of TNFalpha is required for preservation of synaptic strength at excitatory synapses. Through its effects on AMPA receptor trafficking, TNFalpha may play roles in synaptic plasticity and modulating responses to neural injury.

Concentrations of Dark Halos from Their Assembly Histories

Abstract: We study the relation between the density profiles of dark matter halos and their mass assembly histories using a statistical sample of halos in a high-resolution N-body simulation of the ΛCDM cosmology. For each halo at z = 0, we identify its merger history tree and determine concentration parameters cvir for all progenitors, thus providing a structural merger tree for each halo. We fit the mass accretion histories by a universal function with one parameter, the formation epoch ac, defined when the log mass accretion rate d log M/d log a falls below a critical value S. We find that late-forming galaxies tend to be less concentrated, such that cvir "observed" at any epoch ao is strongly correlated with ac via cvir = c1ao/ac. Scatter about this relation is mostly due to measurement errors in cvir and ac, implying that the actual spread in cvir for halos of a given mass can be mostly attributed to scatter in ac. We demonstrate that this relation can also be used to predict the mass and redshift dependence of cvir and the scatter about the median cvir(M, z) using accretion histories derived from the extended Press-Schechter (EPS) formalism, after adjusting for a constant offset between the formation times as predicted by EPS and as measured in the simulations; this new ingredient can thus be easily incorporated into semianalytic models of galaxy formation. The correlation found between halo concentration and mass accretion rate suggests a physical interpretation: for high mass infall rates, the central density is related to the background density; when the mass infall rate slows, the central density stays approximately constant, and the halo concentration just grows as Rvir. Because of the direct connection between halo concentration and velocity rotation curves and because of probable connections between halo mass assembly history and star formation history, the tight correlation between these properties provides an essential new ingredient for galaxy formation modeling.

Effect of fixatives and tissue processing on the content and integrity of nucleic acids.

Abstract: Clinical and molecular medicines are undergoing a revolution based on the accelerated advances in biotechnology such as DNA microarrays and proteomics. Answers to fundamental questions such as how does the DNA sequence differ between individuals and what makes one individual more prone for a certain disease are eagerly being sought in this postgenomic era. Several government and nonprofit organizations provide the researchers access to human tissues for molecular studies. The tissues procured by the different organizations may differ with respect to fixation and processing parameters that may affect significantly the molecular profile of the tissues. It is imperative that a prospective investigator be aware of the potential contributing factors before designing a project. The purpose of this review is to provide an overview of the methods of human tissue acquisition, fixation, and preservation. In addition, the parameters of procurement and fixation that affect the quality of the tissues at the molecular level are discussed.

Interorganizational Routines and Performance in Strategic Alliances

Abstract: This paper applies evolutionary economics reasoning to the strategic alliance context and examines whether and how routinization processes at the partnering-firm level influence the performance of the cooperative agreement. In doing so, it introduces the concept of interorganizational routines, defined as stable patterns of interaction among two firms developed and refined in the course of repeated collaborations, and suggests that partner-specific, technology-specific, and general experience accumulation at the partnering-firm level influence the extent to which alliances result in knowledge accumulation, create new growth opportunities, and enable partnering firms to achieve their strategic objectives. We also consider how governance design choices at the transaction level shape the effectiveness of interorganizational routizination processes. Based on a sample of 145 biotechnology alliances, we find that only partner-specific experience has a positive impact on alliance performance, and that this effect is stronger in the absence of equity-based governance mechanisms. We interpret these results to support the role of interfirm coordination and cooperation routines in enhancing the effectiveness of collaborative agreements.

Distinct effects of T-bet in TH1 lineage commitment and IFN-γ production in CD4 and CD8 T cells

Abstract: T-bet is a member of the T-box family of transcription factors that appears to regulate lineage commitment in CD4 T helper (TH) lymphocytes in part by activating the hallmark TH1 cytokine, interferon-gamma (IFN-gamma). IFN-gamma is also produced by natural killer (NK) cells and most prominently by CD8 cytotoxic T cells, and is vital for the control of microbial pathogens. Although T-bet is expressed in all these cell types, it is required for control of IFN-gamma production in CD4 and NK cells, but not in CD8 cells. This difference is also apparent in the function of these cell subsets. Thus, the regulation of a single cytokine, IFN-gamma, is controlled by distinct transcriptional mechanisms within the T cell lineage.

Emotions, morbidity, and mortality: new perspectives from psychoneuroimmunology.

Abstract: Negative emotions can intensify a variety of health threats. We provide a broad framework relating negative emotions to a range of diseases whose onset and course may be influenced by the immune system; inflammation has been linked to a spectrum of conditions associated with aging, including cardiovascular disease, osteoporosis, arthritis, type 2 diabetes, certain cancers, Alzheimer's disease, frailty and functional decline, and periodontal disease. Production of proinflammatory cytokines that influence these and other conditions can be directly stimulated by negative emotions and stressful experiences. Additionally, negative emotions also contribute to prolonged infection and delayed wound healing, processes that fuel sustained proinflammatory cytokine production. Accordingly, we argue that distress-related immune dysregulation may be one core mechanism behind a large and diverse set of health risks associated with negative emotions. Resources such as close personal relationships that diminish negative emotions enhance health in part through their positive impact on immune and endocrine regulation.

Institutional distance and the multinational enterprise

Abstract: We draw from the recently developed construct of institutional distance to propose a framework that explains foreign direct investment by the multinational enterprise. We decompose the institutional distance between the host and home countries into distances on the regulative, normative, and cognitive dimensions of institutions, and match these with firm-level attributes to produce propositions regarding host country selection and foreign market entry strategies.

Social Capital and Democracy: An Interdependent Relationship

Abstract: Current democratic theory and recent international policy initiatives reveal an intense interest in the relationship between social capital and democracy. This interest is the most recent variant of a long theoretical tradition positing that a vigorous associational life is beneficial for the creation and maintenance of democracy. Despite the popularity of this view, little quantitative empirical evidence exists to support the relationship. Here, the relationship between social capital and democracy is tested using data from a large, quantitative, cross-national study. Two additional tests are introduced. First, the plausible reciprocal effect-from democracy to social capital-is included in models. Second, the potentially negative impact of some associations on democracy is considered. Using data from the World Values Survey and the Union of International Associations in a cross-lagged panel design, results show that social capital affects democracy and that democracy affects social capital. Additional tests demonstrate that associations that are connected to the larger community have a positive effect on democracy, while isolated associations have a negative effect. Theory relating social capital to democracy is drawn from the literature on civil society, political culture, and social movements.

Loneliness and health: potential mechanisms.

Abstract: Objective Two studies using cross-sectional designs explored four possible mechanisms by which loneliness may have deleterious effects on health: health behaviors, cardiovascular activation, cortisol levels, and sleep. Methods In Study 1, we assessed autonomic activity, salivary cortisol levels, sleep quality, and health behaviors in 89 undergraduate students selected based on pretests to be among the top or bottom quintile in feelings of loneliness. In Study 2, we assessed blood pressure, heart rate, salivary cortisol levels, sleep quality, and health behaviors in 25 older adults whose loneliness was assessed at the time of testing at their residence. Results Total peripheral resistance was higher in lonely than nonlonely participants, whereas cardiac contractility, heart rate, and cardiac output were higher in nonlonely than lonely participants. Lonely individuals also reported poorer sleep than nonlonely individuals. Study 2 indicated greater age-related increases in blood pressure and poorer sleep quality in lonely than nonlonely older adults. Mean salivary cortisol levels and health behaviors did not differ between groups in either study. Conclusions Results point to two potentially orthogonal predisease mechanisms that warrant special attention: cardiovascular activation and sleep dysfunction. Health behavior and cortisol regulation, however, may require more sensitive measures and large sample sizes to discern their roles in loneliness and health.

The Halo Occupation Distribution: Toward an Empirical Determination of the Relation between Galaxies and Mass

Abstract: We investigate galaxy bias in the framework of the halo occupation distribution (HOD), which defines the bias of a population of galaxies by the conditional probability P(N|M) that a dark matter halo of virial mass M contains N galaxies, together with prescriptions that specify the relative spatial and velocity distributions of galaxies and dark matter within halos. By populating the halos of a cosmological N-body simulation using a variety of HOD models, we examine the sensitivity of different galaxy clustering statistics to properties of the HOD. The galaxy correlation function responds to different aspects of P(N|M) on different scales. Obtaining the observed power-law form of ξg(r) requires rather specific combinations of HOD parameters, implying a strong constraint on the physics of galaxy formation; the success of numerical and semianalytic models in reproducing this form is entirely nontrivial. Other clustering statistics such as the galaxy-mass correlation function, the bispectrum, the void probability function, the pairwise velocity dispersion, and the group multiplicity function are sensitive to different combinations of HOD parameters and thus provide complementary information about galaxy bias. We outline a strategy for determining the HOD empirically from redshift survey data. This method starts from an assumed cosmological model, but we argue that cosmological and HOD parameters will have nondegenerate effects on galaxy clustering, so that a substantially incorrect cosmological model will not reproduce the observations for any choice of HOD. Empirical determinations of the HOD as a function of galaxy type from the Two-Degree Field (2dF) and Sloan Digital Sky Survey (SDSS) redshift surveys will provide a detailed target for theories of galaxy formation, insight into the origin of galaxy properties, and sharper tests of cosmological models.

Cross-cutting Social Networks: Testing Democratic Theory in Practice

Abstract: Recent social and political theory has elevated political conversation among democratic citizens to new heights. Political talk is central to most current conceptions of how democracy functions (Schudson 1997). According to many prominent social theorists, democracy has a future only if “citizens come back out of their bunkers and start talking” (Gray 1995, 1; see also Elshtain 1995; Lasch 1995). The quantity and quality of political conversation have become “a standard for the accomplishment of democracy” (Sanders 1997, 347). Theorists extol the virtues of political talk, foundations spend millions of dollars to encourage it, and civic journalists and others plan special meetings to foster more of it. Yet what do we really know about beneficial outcomes of political talk as it occurs in day to day life? For the most part, arguments for the centrality of political discussion among ordinary Americans have been highly theoretical in nature. In other words, the contributions to democratic ends that political conversations are supposed to make depend critically on whether such talk reaches the standards necessary to be deemed “deliberation,” “discourse,” or, in Habermas’ (1989) terms, an “ideal speech situation.” It is one thing to claim that political conversation has the potential to produce beneficial outcomes if it meets a whole variety of as yet unrealized criteria, and yet another to argue that political conversations, as they actually occur, produce meaningful benefits for citizens (Conover and Searing 1998). Because the list of requirements for deliberation tends to be quite lengthy, 1 it is difficult, if not impossible, to test theories of this kind empirically.

A Social Actor Conception of Organizational Identity and Its Implications for the Study of Organizational Reputation

Abstract: The objective of this article is to clarify the conceptual domains of organizational identity, image, and reputation. To initiate this theory development process, we present a “social actor” conception of organizational identity. Identity-congruent definitions of image and reputation are then specified and an integrated model proposed. With the aid of this model, a structural flawin the organizational reputation literature is identified and suitable remedies proposed. In addition, the authors explore the implications of invoking identity and identification in explanations and justifications of organizational reputation.

Kilimanjaro Ice Core Records: Evidence of Holocene Climate Change in Tropical Africa

Abstract: Six ice cores from Kilimanjaro provide an ∼11.7-thousand-year record of Holocene climate and environmental variability for eastern equatorial Africa, including three periods of abrupt climate change: ∼8.3, ∼5.2, and ∼4 thousand years ago (ka). The latter is coincident with the “First Dark Age,” the period of the greatest historically recorded drought in tropical Africa. Variable deposition of F – and Na + during the African Humid Period suggests rapidly fluctuating lake levels between ∼11.7 and 4 ka. Over the 20th century, the areal extent of Kilimanjaro9s ice fields has decreased ∼80%, and if current climatological conditions persist, the remaining ice fields are likely to disappear between 2015 and 2020.

Semiclassical quantization of rotating superstring in AdS(5) x S**5

Abstract: Motivated by recent proposals in hep-th/0202021 and hep-th/0204051 we develop semiclassical quantization of superstring in $AdS_5 x S^5$. We start with a classical solution describing string rotating in $AdS_5$ and boosted along large circle of $S^5$. The energy of the classical solution $E$ is a function of the spin $S$ and the momentum $J$ (R-charge) which interpolates between the limiting cases S=0 and J=0 considered previously. We derive the corresponding quadratic fluctuation action for bosonic and fermionic fields from the GS string action and compute the string 1-loop (large $\lambda= {R^4\over \a'^2}$) correction to the classical energy spectrum in the $(S,J)$ sector. We find that the 1-loop correction to the ground-state energy does not cancel for non-zero $S$. For large $S$ it scales as $\ln S$, i.e. as the classical term, with no higher powers of $\ln S$ appearing. This supports the conjecture made in hep-th/0204051 that the classical $E-S = a \ln S$ scaling can be interpolated to weak coupling to reproduce the corresponding operator anomalous dimension behaviour in gauge theory.