Showing papers by "Rutgers University published in 2001"

Final Results from the Hubble Space Telescope Key Project to Measure the Hubble Constant

Abstract: We present here the final results of the Hubble Space Telescope (HST) Key Project to measure the Hubble constant. We summarize our method, the results, and the uncertainties, tabulate our revised distances, and give the implications of these results for cosmology. Our results are based on a Cepheid calibration of several secondary distance methods applied over the range of about 60-400 Mpc. The analysis presented here benefits from a number of recent improvements and refinements, including (1) a larger LMC Cepheid sample to define the fiducial period-luminosity (PL) relations, (2) a more recent HST Wide Field and Planetary Camera 2 (WFPC2) photometric calibration, (3) a correction for Cepheid metallicity, and (4) a correction for incompleteness bias in the observed Cepheid PL samples. We adopt a distance modulus to the LMC (relative to which the more distant galaxies are measured) of μ0 = 18.50 ± 0.10 mag, or 50 kpc. New, revised distances are given for the 18 spiral galaxies for which Cepheids have been discovered as part of the Key Project, as well as for 13 additional galaxies with published Cepheid data. The new calibration results in a Cepheid distance to NGC 4258 in better agreement with the maser distance to this galaxy. Based on these revised Cepheid distances, we find values (in km s-1 Mpc-1) of H0 = 71 ± 2 ± 6 (systematic) (Type Ia supernovae), H0 = 71 ± 3 ± 7 (Tully-Fisher relation), H0 = 70 ± 5 ± 6 (surface brightness fluctuations), H0 = 72 ± 9 ± 7 (Type II supernovae), and H0 = 82 ± 6 ± 9 (fundamental plane). We combine these results for the different methods with three different weighting schemes, and find good agreement and consistency with H0 = 72 ± 8 km s-1 Mpc-1. Finally, we compare these results with other, global methods for measuring H0.

Noncommutative field theory

Abstract: This article reviews the generalization of field theory to space-time with noncommuting coordinates, starting with the basics and covering most of the active directions of research. Such theories are now known to emerge from limits of M theory and string theory and to describe quantum Hall states. In the last few years they have been studied intensively, and many qualitatively new phenomena have been discovered, on both the classical and the quantum level.

Neurogenesis in the adult is involved in the formation of trace memories

Abstract: The vertebrate brain continues to produce new neurons throughout life. In the rat hippocampus, several thousand are produced each day, many of which die within weeks. Associative learning can enhance their survival; however, until now it was unknown whether new neurons are involved in memory formation. Here we show that a substantial reduction in the number of newly generated neurons in the adult rat impairs hippocampal-dependent trace conditioning, a task in which an animal must associate stimuli that are separated in time. A similar reduction did not affect learning when the same stimuli are not separated in time, a task that is hippocampal-independent. The reduction in neurogenesis did not induce death of mature hippocampal neurons or permanently alter neurophysiological properties of the CA1 region, such as long-term potentiation. Moreover, recovery of cell production was associated with the ability to acquire trace memories. These results indicate that newly generated neurons in the adult are not only affected by the formation of a hippocampal-dependent memory, but also participate in it.

Ad hoc positioning system (APS)

Abstract: Many ad hoc network protocols and applications assume the knowledge of geographic location of nodes. The absolute location of each networked node is an assumed fact by most sensor networks which can then present the sensed information on a geographical map. Finding location without the aid of GPS in each node of an ad hoc network is important in cases where GPS is either not accessible, or not practical to use due to power, form factor or line of sight conditions. Location would also enable routing in sufficiently isotropic large networks, without the use of large routing tables. We are proposing APS - a distributed, hop by hop positioning algorithm, that works as an extension of both distance vector routing and GPS positioning in order to provide approximate location for all nodes in a network where only a limited fraction of nodes have self location capability.

Species contributions to PM2.5 mass concentrations: Revisiting common assumptions for estimating organic mass

Abstract: (2001). Species Contributions to PM2.5 Mass Concentrations: Revisiting Common Assumptions for Estimating Organic Mass. Aerosol Science and Technology: Vol. 35, No. 1, pp. 602-610.

Unified huntington’s disease rating scale: Reliability and consistency

Abstract: The Unified Huntington's disease Rating Scale (UHDRS) was developed as a clinical rating scale to assess four domains of clinical performance and capacity in HD: motor function, cognitive function, behavioral abnormalities, and functional capacity. We assessed the internal consistency and the intercorrelations for the four domains and examined changes in ratings over time. We also performed an interrater reliability study of the motor assessment. We found there was a high degree of internal consistency within each of the domains of the UHDRS and that there were significant intercorrelations between the domains of the UHDRS, with the exception of the total behavioral score. There was an excellent degree of interrater reliability for the motor scores. Our limited longitudinal database indicates that the UHDRS may be useful for tracking changes in the clinical features of HD over time. The UHDRS assesses relevant clinical features of HD and appears to be appropriate for repeated administration during clinical studies.

Guanxi and organizational dynamics: Organizational networking in Chinese firms

Abstract: This paper focuses on the utilization of guanxi, which is an important cultural and social element in China, and the impact of guanxi on firm performance. Although guanxi is embedded in every aspect of Chinese social life, companies demonstrate different needs and capacity for guanxi cultivation. Chinese firms develop guanxi as a strategic mechanism to overcome competitive and resource disadvantages by cooperating and exchanging favors with competitive forces and government authorities. We develop an integrative framework theorizing guanxi utilization according to institutional, strategic, and organizational factors, and we explore the impact of guanxi on firm performance, primarily sales growth and net profit growth. Our findings, based on a survey of 128 firms in central China, provide strong support that institutional, strategic, and organizational factors are critical determinants of guanxi with competitive forces. However, only institutional and strategic factors are significant for guanxi utilization with government authorities. In general, guanxi leads to higher firm performance, but is limited to increased sales growth, and has little impact on profit growth. Guanxi benefits market expansion and competitive positioning of firms, but does not enhance internal operations. Copyright © 2001 John Wiley & Sons, Ltd.

Travel and the built environment: a synthesis

Abstract: The potential to moderate travel demand through changes in the built environment is the subject of more than 50 recent empirical studies. The majority of recent studies are summarized. Elasticities of travel demand with respect to density, diversity, design, and regional accessibility are then derived from selected studies. These elasticity values may be useful in travel forecasting and sketch planning and have already been incorporated into one sketch planning tool, the Environmental Protection Agency's Smart Growth Index model. In weighing the evidence, what can be said, with a degree of certainty, about the effects of built environments on key transportation "outcome" variables: trip frequency, trip length, mode choice, and composite measures of travel demand, vehicle miles traveled (VMT) and vehicle hours traveled (VHT)? Trip frequencies have attracted considerable academic interest of late. They appear to be primarily a function of socioeconomic characteristics of travelers and secondarily a function...

Prescriptive Gender Stereotypes and Backlash Toward Agentic Women

Abstract: In an experiment, job description and applicants' attributes were examined as moderators of the backlash effect, the negative evaluation of agentic women for violating prescriptions of feminine niceness (Rudman, 1998). Rutgers University students made hiring decisions for a masculine or “feminized” managerial job. Applicants were presented as either agentic or androgynous. Replicating Rudman and Glick (1999), a feminized job description promoted hiring discrimination against an agentic female because she was perceived as insufficiently nice. Unique to the present research, this perception was related to participants' possession of an implicit (but not explicit) agency-communality stereotype. By contrast, androgynous female applicants were not discriminated against. The findings suggest that the prescription for female niceness is an implicit belief that penalizes women unless they temper their agency with niceness.

Language and agency

Abstract: ▪ Abstract This review describes and critiques some of the many ways agency has been conceptualized in the academy over the past few decades, focusing in particular on practice theorists such as Giddens, Bourdieu, de Certeau, Sahlins, and Ortner. For scholars interested in agency, it demonstrates the importance of looking closely at language and argues that the issues surrounding linguistic form and agency are relevant to anthropologists with widely divergent research agendas. Linguistic anthropologists have made significant contributions to the understanding of agency as it emerges in discourse, and the final sections of this essay describe some of the most promising research in the study of language and gender, literacy practices, and the dialogic construction of meaning and agency.

Maximally localized Wannier functions for entangled energy bands

Abstract: We present a method for obtaining well-localized Wannier-like functions (WF's) for energy bands that are attached to or mixed with other bands. The present scheme removes the limitation of the usual maximally localized WF's method [N. Marzari and D. Vanderbilt, Phys. Rev. B 56, 12 847 (1997)] that the bands of interest should form an isolated group, separated by gaps from higher and lower bands everywhere in the Brillouin zone. An energy window encompassing N bands of interest is specified by the user, and the algorithm then proceeds to disentangle these from the remaining bands inside the window by filtering out an optimally connected N-dimensional subspace. This is achieved by minimizing a functional that measures the subspace dispersion across the Brillouin zone. The maximally localized WF's for the optimal subspace are then obtained via the algorithm of Marzari and Vanderbilt. The method, which functions as a postprocessing step using the output of conventional electronic-structure codes, is applied to the s and d bands of copper, and to the valence and low-lying conduction bands of silicon. For the low-lying nearly-free-electron bands of copper we find WF's which are centered at the tetrahedral-interstitial sites, suggesting an alternative tight-binding parametrization.

Inhibition of carcinogenesis by dietary polyphenolic compounds

Abstract: Plants consumed by humans contain thousands of phenolic compounds. The effects of dietary polyphenols are of great current interest due to their antioxidative and possible anticarcinogenic activities. A popular belief is that dietary polyphenols are anticarcinogens because they are antioxidants, but direct evidence for this supposition is lacking. This chapter reviews the inhibition of tumorigenesis by phenolic acids and derivatives, tea and catechins, isoflavones and soy preparations, quercetin and other flavonoids, resveratrol, and lignans as well as the mechanisms involved based on studies in vivo and in vitro. Polyphenols may inhibit carcinogenesis by affecting the molecular events in the initiation, promotion, and progression stages. Isoflavones and lignans may influence tumor formation by affecting estrogen-related activities. The bioavailability of the dietary polyphenols is discussed extensively, because the tissue levels of the effective compounds determine the biological activity. Understanding the bioavailability and blood and tissue levels of polyphenols is also important in extrapolating results from studies in cell lines to animal models and humans. Epidemiological studies concerning polyphenol consumption and human cancer risk suggest the protective effects of certain food items and polyphenols, but more studies are needed for clear-cut conclusions. Perspectives on the application of dietary polyphenols for the prevention of human cancer and possible concerns on the consumption of excessive amounts of polyphenols are discussed.

Boundary Organizations in Environmental Policy and Science: An Introduction

Abstract: Scholarship in the social studies of science has argued convincingly that what demarcates science from nonscience is not some set of essential or transcendent characteristics or methods but rather an array of contingent circumstances and strategic behavior known as "boundary work" (Gieryn 1995, 1999). Although initially formulated to explain how scientists maintain the boundaries of their community against threats to its cognitive authority from within (e.g., fraud and pseudo-science), boundary work has found useful, policy-relevant applications-for example, in studying the strategic demarcation between political and scientific tasks in the advisory relationship between scientists and regulatory agencies (Jasanoff 1990). This work finds that the blurring of boundaries between science and politics, rather than the intentional separation often advocated and practiced, can lead to more productive policy making. If it is the case, however, that the robustness of scientific concepts such as causation and representation are important components of liberal-democratic thought and practice (Ezrahi 1990), one can imagine how the flexibility of boundary work might lead to confusion or even dangerous instabilities between science and nonscience. These risks could be conceived, perhaps, as the politicization of science or the reciprocal scientification of politics. Neither risk should here be understood to mean the importation to one enterprise from the other elements that are entirely foreign; that is, science is not devoid of values prior to some politicization, nor politics of rationality, prior to any scientification. Rather, both should be understood to mean the rendering of norms and practices in one enterprise in a way that unreflexively mimics norms and practices in the other. These concerns have been central to the socalled science wars, and to the extent that they are implicated in public discussions of such policy issues as health and safety regulation, climate change, or genetically modified organisms, they are real problems for policy makers and publics alike.'

Epidemic Increase in Childhood Overweight, 1986-1998

Abstract: ContextOverweight is the most common health problem facing US children. Data for adults suggest that overweight prevalence has increased by more than 50% in the last 10 years. Data for children also suggest that the prevalence of overweight continues to increase rapidly.ObjectiveTo investigate recent changes in the prevalence of overweight within a nationally representative sample of children.Design, Setting, and ParticipantsThe National Longitudinal Survey of Youth, a prospective cohort study conducted from 1986 to 1998 among 8270 children aged 4 to 12 years (24 174 growth points were analyzed).Main Outcome MeasuresPrevalence of overweight children, defined as body mass index (BMI) greater than the 95th percentile for age and sex, and prevalence of overweight and at-risk children, defined as BMI greater than the 85th percentile for age and sex. The roles of race/ethnicity, sex, income, and region of residence were also examined.ResultsBetween 1986 and 1998, overweight increased significantly and steadily among African American (P<.001), Hispanic (P<.001), and white (P = .03) children. By 1998, overweight prevalence increased to 21.5% among African Americans, 21.8% among Hispanics, and 12.3% among non-Hispanic whites. In addition, overweight children were heavier in 1998 compared with 1986 (P<.001). After adjusting for confounding variables, overweight increased fastest among minorities and southerners, creating large demographic differences in the prevalence of childhood overweight by 1998. The number of children with BMI greater than the 85th percentile increased significantly from 1986 to 1998 among African American and Hispanic children (P<.001 for both) and nonsignificantly among white children (P = .77).ConclusionsChildhood overweight continues to increase rapidly in the United States, particularly among African Americans and Hispanics. Culturally competent treatment strategies as well as other policy interventions are required to increase physical activity and encourage healthy eating patterns among children.

Searching the Web: the public and their queries

Abstract: In studying actual Web searching by the public at large, we analyzed over one million Web queries by users of the Excite search engine. We found that most people use few search terms, few modified queries, view few Web pages, and rarely use advanced search features. A small number of search terms are used with high frequency, and a great many terms are unique; the language of Web queries is distinctive. Queries about recreation and entertainment rank highest. Findings are compared to data from two other large studies of Web queries. This study provides an insight into the public practices and choices in Web searching.

Advantages and Disadvantages of Cognitive Heuristics in Political Decision Making

Abstract: This article challenges the often un- tested assumption that cognitive "heuristics" improve the decision- making abilities of everyday voters. The potential benefits and costs of five common political heuristics are discussed. A new dynamic process- tracing methodology is employed to directly observe the use of these five heuristics by voters in a mock presi- dential election campaign. We find that cognitive heuristics are at times employed by almost all voters and that they are particularly likely to be used when the choice situation facing voters is complex. A hypothesized

Cheating in Academic Institutions: A Decade of Research

Abstract: This article reviews 1 decade of research on cheating in academic institutions. This research demonstrates that cheating is prevalent and that some forms of cheating have increased dramatically in the last 30 years. This research also suggests that although both individual and contextual factors influence cheating, contextual factors, such as students' perceptions of peers' behavior, are the most powerful influence. In addition, an institution's academic integrity programs and policies, such as honor codes, can have a significant influence on students' behavior. Finally, we offer suggestions for managing cheating from students' and faculty members' perspectives.

Growth process conditions of vertically aligned carbon nanotubes using plasma enhanced chemical vapor deposition

Abstract: The growth of vertically aligned carbon nanotubes using a direct current plasma enhanced chemical vapor deposition system is reported. The growth properties are studied as a function of the Ni catalyst layer thickness, bias voltage, deposition temperature, C2H2:NH3 ratio, and pressure. It was found that the diameter, growth rate, and areal density of the nanotubes are controlled by the initial thickness of the catalyst layer. The alignment of the nanotubes depends on the electric field. Our results indicate that the growth occurs by diffusion of carbon through the Ni catalyst particle, which rides on the top of the growing tube.

Interactive memory systems in the human brain.

Abstract: Learning and memory in humans rely upon several memory systems, which appear to have dissociable brain substrates1,2. A fundamental question concerns whether, and how, these memory systems interact. Here we show using functional magnetic resonance imaging (FMRI) that these memory systems may compete with each other during classification learning in humans. The medial temporal lobe and basal ganglia were differently engaged across subjects during classification learning depending upon whether the task emphasized declarative or nondeclarative memory, even when the to-be-learned material and the level of performance did not differ. Consistent with competition between memory systems suggested by animal studies3,4 and neuroimaging5, activity in these regions was negatively correlated across individuals. Further examination of classification learning using event-related FMRI showed rapid modulation of activity in these regions at the beginning of learning, suggesting that subjects relied upon the medial temporal lobe early in learning. However, this dependence rapidly declined with training, as predicted by previous computational models of associative learning6,7,8.

Osteopontin as a means to cope with environmental insults: regulation of inflammation, tissue remodeling, and cell survival

Abstract: OPN is a multifunctional cytokine and adhesion protein that contains an integrin-binding RGD sequence and additional sequences that interact with CD44v6/7 or other adhesive receptors. Its expression is increased in response to early proinflammatory cytokines and to mechanical strain in bone. The function of the secreted protein may be altered by extracellular enzymes, including thrombin and kinases. The study of OPN-null mice has revealed roles for OPN in a broad range of homeostatic (bone remodeling, tissue debridement) and pathologic (cellular immunity, wound healing, cancer metastasis) processes. While these processes seem disparate, they are linked by several common themes, including enhanced expression of OPN in response to stress or tissue injury, and stimulation of cell motility and cell survival pathways via interactions of OPN with adhesive receptors. OPN is chemotactic for various cell types, notably monocytes/macrophages, which are attracted to sites of infection and inflammation. It is essential for cell-mediated immunity and a normal Th1 cytokine response during granuloma formation. OPN serves both to attach bone cells to bone matrix and to generate intracellular signals essential for normal osteoclast motility on bone; it may mediate osteocyte recognition of bone strain. OPN activates intracellular signaling pathways and regulates gene expression as a consequence of its interactions with its various receptors. The best-characterized is the integrin-stimulated FAK-Src-Rho pathway, which alters gelsolin function and podosome formation in osteoclasts. Identification and dissection of the signal transduction pathways and their targets are complicated by the fact that OPN can engage more than one type of receptor on the cell. For this reason, it is important to ascertain which receptors are in play in any given experimental system. There is compelling evidence that soluble OPN can in a variety of situations help cells survive an otherwise lethal insult. Remarkably, this survival signaling is mediated by receptors that are generally considered to be receptors for ECM components. We suggest that OPN delivers an antiapoptotic “ECM-like” signal via multiple ligand-receptor interactions to cells, both adherent and nonadherent.

Programmed cell death, mitochondria and the plant hypersensitive response

Abstract: The plant response to attempted infection by microbial pathogens is often accompanied by rapid cell death in and around the initial infection site, a reaction known as the hypersensitive response. This response is associated with restricted pathogen growth and represents a form of programmed cell death (PCD). Recent pharmacological and molecular studies have provided functional evidence for the conservation of some of the basic regulatory mechanisms underlying the response to pathogens and the activation of PCD in animal and plant systems. In animals, the mitochondrion integrates diverse cellular stress signals and initiates the death execution pathway, and studies indicate a similar involvement for mitochondria in regulating PCD in plants. But many of the cell-death regulators that have been characterized in humans, worms and flies are absent from the Arabidopsis genome, indicating that plants probably use other regulators to control this process.

The influence of the proinflammatory cytokine, osteopontin, on autoimmune demyelinating disease.

Abstract: Multiple sclerosis is a demyelinating disease, characterized by inflammation in the brain and spinal cord, possibly due to autoimmunity. Large-scale sequencing of cDNA libraries, derived from plaques dissected from brains of patients with multiple sclerosis (MS), indicated an abundance of transcripts for osteopontin (OPN). Microarray analysis of spinal cords from rats paralyzed by experimental autoimmune encephalomyelitis (EAE), a model of MS, also revealed increased OPN transcripts. Osteopontin-deficient mice were resistant to progressive EAE and had frequent remissions, and myelin-reactive T cells in OPN-/- mice produced more interleukin 10 and less interferon-gamma than in OPN+/+ mice. Osteopontin thus appears to regulate T helper cell-1 (TH1)-mediated demyelinating disease, and it may offer a potential target in blocking development of progressive MS.

The DNA replication checkpoint response stabilizes stalled replication forks

Abstract: In response to DNA damage and blocks to replication, eukaryotes activate the checkpoint pathways that prevent genomic instability and cancer by coordinating cell cycle progression with DNA repair. In budding yeast, the checkpoint response requires the Mec1-dependent activation of the Rad53 protein kinase. Active Rad53 slows DNA synthesis when DNA is damaged and prevents firing of late origins of replication. Further, rad53 mutants are unable to recover from a replication block. Mec1 and Rad53 also modulate the phosphorylation state of different DNA replication and repair enzymes. Little is known of the mechanisms by which checkpoint pathways interact with the replication apparatus when DNA is damaged or replication blocked. We used the two-dimensional gel technique to examine replication intermediates in response to hydroxyurea-induced replication blocks. Here we show that hydroxyurea-treated rad53 mutants accumulate unusual DNA structures at replication forks. The persistence of these abnormal molecules during recovery from the hydroxyurea block correlates with the inability to dephosphorylate Rad53. Further, Rad53 is required to properly maintain stable replication forks during the block. We propose that Rad53 prevents collapse of the fork when replication pauses.

Promoting the Utilization of Performance Measures in Public Organizations: An Empirical Study of Factors Affecting Adoption and Implementation

Abstract: Despite its appeal for improving government, many state and local governments have not developed performance-measurement systems, and even fewer use these systems to improve decision making. This study examines the factors that affect the utilization of performance measurement, based on the results of a national survey of state and local government officials. The goals of the study were to provide better information on the patterns of usage of performance measurement and to use this information to develop an elaborated model of the factors presumed to affect utilization. Using distinctions from the policy and evaluation literature, hypotheses were tested and confirmed: Policy adoption is driven more heavily by factors from rational and technocratic theory, whereas actual implementation is influenced by factors addressed by political and cultural considerations.

The cap-to-tail guide to mRNA turnover

Abstract: The levels of cellular messenger RNA transcripts can be regulated by controlling the rate at which the mRNA decays. Because decay rates affect the expression of specific genes, they provide a cell with flexibility in effecting rapid change. Moreover, many clinically relevant mRNAs — including several encoding cytokines, growth factors and proto-oncogenes — are regulated by differential RNA stability. But what are the sequence elements and factors that control the half-lives of mRNAs?