Showing papers by "Pennsylvania State University published in 2006"
TL;DR: A review of the different materials and methods used to construct MFCs, techniques used to analyze system performance, and recommendations on what information to include in MFC studies and the most useful ways to present results are provided.
Abstract: Microbial fuel cell (MFC) research is a rapidly evolving field that lacks established terminology and methods for the analysis of system performance. This makes it difficult for researchers to compare devices on an equivalent basis. The construction and analysis of MFCs requires knowledge of different scientific and engineering fields, ranging from microbiology and electrochemistry to materials and environmental engineering. Describing MFC systems therefore involves an understanding of these different scientific and engineering principles. In this paper, we provide a review of the different materials and methods used to construct MFCs, techniques used to analyze system performance, and recommendations on what information to include in MFC studies and the most useful ways to present results.
5,024 citations
University of Tennessee1, Oak Ridge National Laboratory2, West Virginia University3, Umeå University4, University of British Columbia5, United States Department of Energy6, Ghent University7, Swedish University of Agricultural Sciences8, Institut national de la recherche agronomique9, Virginia Tech10, Michigan Technological University11, University of Toronto12, Pennsylvania State University13, University of Provence14, University of Georgia15, University of Florida16, University of California, Berkeley17, Lawrence Berkeley National Laboratory18, University of Arizona19, Purdue University20, Stanford University21, United States Department of Agriculture22, University of Helsinki23, University of Turku24, Massachusetts Institute of Technology25, University of Tennessee Health Science Center26, University of Tübingen27
TL;DR: The draft genome of the black cottonwood tree, Populus trichocarpa, has been reported in this paper, with more than 45,000 putative protein-coding genes identified.
Abstract: We report the draft genome of the black cottonwood tree, Populus trichocarpa. Integration of shotgun sequence assembly with genetic mapping enabled chromosome-scale reconstruction of the genome. More than 45,000 putative protein-coding genes were identified. Analysis of the assembled genome revealed a whole-genome duplication event; about 8000 pairs of duplicated genes from that event survived in the Populus genome. A second, older duplication event is indistinguishably coincident with the divergence of the Populus and Arabidopsis lineages. Nucleotide substitution, tandem gene duplication, and gross chromosomal rearrangement appear to proceed substantially more slowly in Populus than in Arabidopsis. Populus has more protein-coding genes than Arabidopsis, ranging on average from 1.4 to 1.6 putative Populus homologs for each Arabidopsis gene. However, the relative frequency of protein domains in the two genomes is similar. Overrepresented exceptions in Populus include genes associated with lignocellulosic wall biosynthesis, meristem development, disease resistance, and metabolite transport.
4,025 citations
TL;DR: The International Personality Item Pool (IPIP) as mentioned in this paper has been used as a prototype for public-domain personality measures, focusing on the International personality item pool, which has been widely used for personality measurement.
2,822 citations
TL;DR: Adhering to these diet and lifestyle recommendations, Americans can substantially reduce their risk of developing cardiovascular disease, which remains the leading cause of morbidity and mortality in the United States.
Abstract: Improving diet and lifestyle is a critical component of the American Heart Association's strategy for cardiovascular disease risk reduction in the general population. This document presents recommendations designed to meet this objective. Specific goals are to consume an overall healthy diet; aim for a healthy body weight; aim for recommended levels of low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides; aim for normal blood pressure; aim for a normal blood glucose level; be physically active; and avoid use of and exposure to tobacco products. The recommendations are to balance caloric intake and physical activity to achieve and maintain a healthy body weight; consume a diet rich in vegetables and fruits; choose whole-grain, high-fiber foods; consume fish, especially oily fish, at least twice a week; limit intake of saturated fat to 7% of energy, trans fat to 1% of energy, and cholesterol to 300 mg/day by choosing lean meats and vegetable alternatives, fat-free (skim) or low-fat (1% fat) dairy products and minimize intake of partially hydrogenated fats; minimize intake of beverages and foods with added sugars; choose and prepare foods with little or no salt; if you consume alcohol, do so in moderation; and when you eat food prepared outside of the home, follow these Diet and Lifestyle Recommendations. By adhering to these diet and lifestyle recommendations, Americans can substantially reduce their risk of developing cardiovascular disease, which remains the leading cause of morbidity and mortality in the United States. (Circulation. 2006;114:82-96.)
2,769 citations
TL;DR: In this article, a literature review focuses on the emerging construct of ethical leadership and compares this construct with related concepts that share a common concern for a moral dimension of leadership (e.g., spiritual, authentic, and transformational leadership).
Abstract: Our literature review focuses on the emerging construct of ethical leadership and compares this construct with related concepts that share a common concern for a moral dimension of leadership (e.g., spiritual, authentic, and transformational leadership). Drawing broadly from the intersection of the ethics and leadership literatures, we offer propositions about the antecedents and outcomes of ethical leadership. We also identify issues and questions to be addressed in the future and discuss their implications for research and practice. Our review indicates that ethical leadership remains largely unexplored, offering researchers opportunities for new discoveries and leaders opportunities to improve their effectiveness.
2,542 citations
TL;DR: The Sloan Digital Sky Survey (SDS) as discussed by the authors is a two-corrector Ritchey-Chretien design with a 2.5 m, f/2.25 m, a 1.08 m secondary, and one of a pair of interchangeable highly aspheric correctors near the focal plane, one for imaging and the other for spectroscopy.
Abstract: We describe the design, construction, and performance of the Sloan Digital Sky Survey telescope located at Apache Point Observatory. The telescope is a modified two-corrector Ritchey-Chretien design with a 2.5 m, f/2.25 primary, a 1.08 m secondary, a Gascoigne astigmatism corrector, and one of a pair of interchangeable highly aspheric correctors near the focal plane, one for imaging and the other for spectroscopy. The final focal ratio is f/5. The telescope is instrumented by a wide-area, multiband CCD camera and a pair of fiber-fed double spectrographs. Novel features of the telescope include the following: (1) A 3° diameter (0.65 m) focal plane that has excellent image quality and small geometric distortions over a wide wavelength range (3000-10,600 A) in the imaging mode, and good image quality combined with very small lateral and longitudinal color errors in the spectroscopic mode. The unusual requirement of very low distortion is set by the demands of time-delay-and-integrate (TDI) imaging. (2) Very high precision motion to support open-loop TDI observations. (3) A unique wind baffle/enclosure construction to maximize image quality and minimize construction costs. The telescope had first light in 1998 May and began regular survey operations in 2000.
2,264 citations
TL;DR: It is shown that archaeal ammonia oxidizers are more abundant in soils than their well-known bacterial counterparts, and crenarchaeota may be the most abundant ammonia-oxidizing organisms in soil ecosystems on Earth.
Abstract: Ammonia oxidation is the first step in nitrification, a key process in the global nitrogen cycle that results in the formation of nitrate through microbial activity. The increase in nitrate availability in soils is important for plant nutrition, but it also has considerable impact on groundwater pollution owing to leaching. Here we show that archaeal ammonia oxidizers are more abundant in soils than their well-known bacterial counterparts. We investigated the abundance of the gene encoding a subunit of the key enzyme ammonia monooxygenase (amoA) in 12 pristine and agricultural soils of three climatic zones. amoA gene copies of Crenarchaeota (Archaea) were up to 3,000-fold more abundant than bacterial amoA genes. High amounts of crenarchaeota-specific lipids, including crenarchaeol, correlated with the abundance of archaeal amoA gene copies. Furthermore, reverse transcription quantitative PCR studies and complementary DNA analysis using novel cloning-independent pyrosequencing technology demonstrated the activity of the archaea in situ and supported the numerical dominance of archaeal over bacterial ammonia oxidizers. Our results indicate that crenarchaeota may be the most abundant ammonia-oxidizing organisms in soil ecosystems on Earth.
2,260 citations
TL;DR: Voltage-decay measurements indicate that the highly ordered TiO(2) nanotube arrays, in comparison to nanoparticulate systems, have superior electron lifetimes and provide excellent pathways for electron percolation.
Abstract: We describe the use of highly ordered transparent TiO2 nanotube arrays in dye-sensitized solar cells (DSCs). Highly ordered nanotube arrays of 46-nm pore diameter, 17-nm wall thickness, and 360-nm ...
2,142 citations
TL;DR: The Lawson Wilkins Paediatric Endocrine Society (LWPES) and the EPE considered it timely to review the management of intersex disorders from a broad perspective, to review data on longer term outcome and to formulate proposals for future studies.
Abstract: The birth of an intersex child prompts a long-term management strategy that involves a myriad of professionals working with the family. There has been progress in diagnosis, surgical techniques, understanding psychosocial issues and in recognizing and accepting the place of patient advocacy. The Lawson Wilkins Paediatric Endocrine Society (LWPES) and the European Society for Paediatric Endocrinology (ESPE) considered it timely to review the management of intersex disorders from a broad perspective, to review data on longer term outcome and to formulate proposals for future studies. The methodology comprised establishing a number of working groups whose membership was drawn from 50 international experts in the field. The groups prepared prior written responses to a defined set of questions resulting from an evidence based review of the literature. At a subsequent gathering of participants, a framework for a consensus document was agreed. This paper constitutes its final form.
2,108 citations
TL;DR: It is demonstrated that a very high energy density with fast discharge speed and low loss can be obtained in defect-modified poly(vinylidene fluoride) polymers by combining nonpolar and polar molecular structural changes of the polymer with the proper dielectric constants.
Abstract: Dielectric polymers with high dipole density have the potential to achieve very high energy density, which is required in many modern electronics and electric systems. We demonstrate that a very high energy density with fast discharge speed and low loss can be obtained in defect-modified poly(vinylidene fluoride) polymers. This is achieved by combining nonpolar and polar molecular structural changes of the polymer with the proper dielectric constants, to avoid the electric displacement saturation at electric fields well below the breakdown field. The results indicate that a very high dielectric constant may not be desirable to reach a very high energy density.
2,008 citations
TL;DR: In this paper, the fabrication, properties, and solar energy applications of highly ordered TiO 2 nanotube arrays made by anodic oxidation of titanium in fluoride-based electrolytes are reviewed.
University of California, Los Angeles1, University of Palermo2, Lille University of Science and Technology3, National and Kapodistrian University of Athens4, University of Alcalá5, Icahn School of Medicine at Mount Sinai6, University of Duisburg-Essen7, Pennsylvania State University8, University of Adelaide9, Pfizer10, University of Pittsburgh11
TL;DR: It is the view of the AES Task Force on the Phenotype of PCOS that there should be acceptance of the original 1990 National Institutes of Health criteria with some modifications, taking into consideration the concerns expressed in the proceedings of the 2003 Rotterdam conference.
Abstract: Objective: The Androgen Excess Society (AES) charged a task force to review all available data and recommend an evidence-based definition for polycystic ovary syndrome (PCOS), whether already in use or not, to guide clinical diagnosis and future research. Participants: Participants included expert investigators in the field. Evidence: Based on a systematic review of the published peer-reviewed medical literature, by querying MEDLINE databases, we tried to identify studies evaluating the epidemiology or phenotypic aspects of PCOS. Consensus Process: The task force drafted the initial report, following a consensus process via electronic communication, which was then reviewed and critiqued by the AES Board of Directors. No section was finalized until all members were satisfied with the contents and minority opinions noted. Statements that were not supported by peer-reviewed evidence were not included. Conclusions: Based on the available data, it is the view of the AES Task Force on the Phenotype of PCOS that...
TL;DR: The rates of readmission for heart failure and of in-hospital complications did not differ between the two groups, and the survival of patients with heart failure with preserved ejection fraction was similar to that of Patients with reduced ejections fraction.
Abstract: Thirty-one percent of the patients had an ejection fraction of more than 50 percent. Patients with heart failure with preserved ejection fraction were more likely to be older and female and to have a history of hypertension and atrial fibrillation. The presenting history and clinical examination findings were similar for the two groups. The unadjusted mortality rates for patients with an ejection fraction of more than 50 percent were not significantly different from those for patients with an ejection fraction of less than 40 percent at 30 days (5 percent vs. 7 percent, P = 0.08) and at 1 year (22 percent vs. 26 percent, P = 0.07); the adjusted one-year mortality rates were also not significantly different in the two groups (hazard ratio, 1.13; 95 percent confidence interval, 0.94 to 1.36; P = 0.18). The rates of readmission for heart failure and of in-hospital complications did not differ between the two groups. Conclusions Among patients presenting with new-onset heart failure, a substantial proportion had an ejection fraction of more than 50 percent. The survival of patients with heart failure with preserved ejection fraction was similar to that of patients with reduced ejection fraction.
TL;DR: The authors integrate and synthesize what is known about racial and ethnic socialization on the basis of current empirical research, examining studies concerning its nature and frequency; its child, parent, and ecological predictors; and its consequences for children's development, including ethnic identity, self-esteem, coping with discrimination, academic achievement, and psychosocial well-being.
Abstract: Recently, there has been an emergence of literature on the mechanisms through which parents transmit information, values, and perspectives about ethnicity and race to their children, commonly referred to as racial or ethnic socialization. This literature has sought to document the nature of such socialization, its antecedents in parents' and children's characteristics and experiences, and its consequences for children's well-being and development. In this article, the authors integrate and synthesize what is known about racial and ethnic socialization on the basis of current empirical research, examining studies concerning its nature and frequency; its child, parent, and ecological predictors; and its consequences for children's development, including ethnic identity, self-esteem, coping with discrimination, academic achievement, and psychosocial well-being. The authors also discuss conceptual and methodological limitations of the literature and suggest directions for future research.
Duke University1, Oregon State University2, Clark University3, Natural History Museum4, University of Minnesota5, Field Museum of Natural History6, Kaiserslautern University of Technology7, University of Arizona8, New York Botanical Garden9, University of Iowa10, Technische Universität Darmstadt11, University of Maine12, United States Department of Agriculture13, University of Georgia14, University of Alabama15, University of California, Berkeley16, University of Kansas17, Aberystwyth University18, West Virginia University19, Washington State University20, Harvard University21, University of North Carolina at Chapel Hill22, Centraalbureau voor Schimmelcultures23, University of Tennessee24, Okayama University25, University of Kassel26, Brandon University27, Pennsylvania State University28, Leibniz Association29, University of Hamburg30, Royal Botanic Garden Edinburgh31
TL;DR: It is indicated that there may have been at least four independent losses of the flagellum in the kingdom Fungi, and the enigmatic microsporidia seem to be derived from an endoparasitic chytrid ancestor similar to Rozella allomycis, on the earliest diverging branch of the fungal phylogenetic tree.
Abstract: The ancestors of fungi are believed to be simple aquatic forms with flagellated spores, similar to members of the extant phylum Chytridiomycota (chytrids). Current classifications assume that chytrids form an early-diverging clade within the kingdom Fungi and imply a single loss of the spore flagellum, leading to the diversification of terrestrial fungi. Here we develop phylogenetic hypotheses for Fungi using data from six gene regions and nearly 200 species. Our results indicate that there may have been at least four independent losses of the flagellum in the kingdom Fungi. These losses of swimming spores coincided with the evolution of new mechanisms of spore dispersal, such as aerial dispersal in mycelial groups and polar tube eversion in the microsporidia (unicellular forms that lack mitochondria). The enigmatic microsporidia seem to be derived from an endoparasitic chytrid ancestor similar to Rozella allomycis, on the earliest diverging branch of the fungal phylogenetic tree.
TL;DR: In this paper, the authors proposed to use CO2 for environmentally-benign physical and chemical processing that adds value to the process, using CO2 as an alternate medium or solvent or co-reactant or a combination of them.
TL;DR: The preparation of out-of-equilibrium arrays of trapped one-dimensional Bose gases, each containing from 40 to 250 87Rb atoms, which do not noticeably equilibrate even after thousands of collisions are reported.
Abstract: It is a fundamental assumption of statistical mechanics that a closed system with many degrees of freedom ergodically samples all equal energy points in phase space. To understand the limits of this assumption, it is important to find and study systems that are not ergodic, and thus do not reach thermal equilibrium. A few complex systems have been proposed that are expected not to thermalize because their dynamics are integrable. Some nearly integrable systems of many particles have been studied numerically, and shown not to ergodically sample phase space. However, there has been no experimental demonstration of such a system with many degrees of freedom that does not approach thermal equilibrium. Here we report the preparation of out-of-equilibrium arrays of trapped one-dimensional (1D) Bose gases, each containing from 40 to 250 (87)Rb atoms, which do not noticeably equilibrate even after thousands of collisions. Our results are probably explainable by the well-known fact that a homogeneous 1D Bose gas with point-like collisional interactions is integrable. Until now, however, the time evolution of out-of-equilibrium 1D Bose gases has been a theoretically unsettled issue, as practical factors such as harmonic trapping and imperfectly point-like interactions may compromise integrability. The absence of damping in 1D Bose gases may lead to potential applications in force sensing and atom interferometry.
Massachusetts Institute of Technology1, University of Arizona2, Princeton University3, Ohio State University4, New York University5, Fermilab6, University of Chicago7, University of Tokyo8, University of Colorado Boulder9, University of Portsmouth10, Lawrence Berkeley National Laboratory11, Pennsylvania State University12, International Centre for Theoretical Physics13, Johns Hopkins University14, Drexel University15, Case Western Reserve University16, Los Alamos National Laboratory17, University of Washington18, University of Cape Town19, New Mexico State University20, University of Pittsburgh21, Eötvös Loránd University22, Harvard University23, United States Department of the Navy24, University of Pennsylvania25, California Institute of Technology26, University of Sussex27, Seoul National University28, Rochester Institute of Technology29, Hungarian Academy of Sciences30
TL;DR: In this paper, the authors employed a matrix-based power spectrum estimation method using pseudo-Karhunen-Loeve eigenmodes, producing uncorrelated minimum-variance measurements in 20 k-bands of both the clustering power and its anisotropy due to redshift-space distortions.
Abstract: We measure the large-scale real-space power spectrum P(k) using luminous red galaxies (LRGs) in the Sloan Digital Sky Survey (SDSS) and use this measurement to sharpen constraints on cosmological parameters from the Wilkinson Microwave Anisotropy Probe (WMAP). We employ a matrix-based power spectrum estimation method using Pseudo-Karhunen-Loeve eigenmodes, producing uncorrelated minimum-variance measurements in 20 k-bands of both the clustering power and its anisotropy due to redshift-space distortions, with narrow and well-behaved window functions in the range 0.01h/Mpc 0.1h/Mpc and associated nonlinear complications, yet agree well with more aggressive published analyses where nonlinear modeling is crucial.
TL;DR: The authors studied the evolution of the ionization state of the intergalactic medium (IGM) at the end of the reionization epoch using moderate-resolution spectra of a sample of 19 quasars at 5.74 5.7.
Abstract: We study the evolution of the ionization state of the intergalactic medium (IGM) at the end of the reionization epoch using moderate-resolution spectra of a sample of 19 quasars at 5.74 5.7: the GP optical depth evolution changes from τ ~ (1 + z)4.3 to (1 + z)11, and the average length of dark gaps with τ > 3.5 increases from 80 comoving Mpc. The dispersion of IGM properties along different lines of sight also increases rapidly, implying fluctuations by a factor of 4 in the UV background at z > 6, when the mean free path of UV photons is comparable to the correlation length of the star-forming galaxies that are thought to have caused reionization. The mean length of dark gaps shows the most dramatic increase at z ~ 6, as well as the largest line-of-sight variations. We suggest using dark gap statistics as a powerful probe of the ionization state of the IGM at yet higher redshift. The sizes of H II regions around luminous quasars decrease rapidly toward higher redshift, suggesting that the neutral fraction of the IGM has increased by a factor of 10 from z = 5.7 to 6.4, consistent with the value derived from the GP optical depth. The mass-averaged neutral fraction is 1%-4% at z ~ 6.2 based on the GP optical depth and H II region size measurements. The observations suggest that z ~ 6 is the end of the overlapping stage of reionization and are inconsistent with a mostly neutral IGM at z ~ 6, as indicated by the finite length of the dark absorption gaps.
TL;DR: Results of room-temperature Raman scattering studies of ultrathin graphitic films supported on Si (100)/SiO2 substrates are reported, and both the first- and second-order Raman spectra show unique signatures of the number of layers in the film.
Abstract: Results of room-temperature Raman scattering studies of ultrathin graphitic films supported on Si (100)/SiO2 substrates are reported. The results are significantly different from those known for graphite. Spectra were collected using 514.5 nm radiation on films containing from n = 1 to 20 graphene layers, as determined by atomic force microscopy. Both the first- and second-order Raman spectra show unique signatures of the number of layers in the film. The nGL film analogue of the Raman G-band in graphite exhibits a Lorentzian line shape whose center frequency shifts linearly relative to graphite as ∼1/n (for n = 1 ωG ≈ 1587 cm-1). Three weak bands, identified with disorder-induced first-order scattering, are observed at ∼1350, 1450, and 1500 cm-1. The ∼1500 cm-1 band is weak but relatively sharp and exhibits an interesting n-dependence. In general, the intensity of these D-bands decreases dramatically with increasing n. Three second-order bands are also observed (∼2450, ∼2700, and 3248 cm-1). They are ana...
TL;DR: The importance of ethical behavior to an organization has never been more apparent, and in recent years researchers have generated a great deal of knowledge about the management of individual ethical behavior in organizations.
TL;DR: A large electric-field response of quasi–two-dimensional electron gases generated at interfaces in epitaxial heterostructures grown from insulating oxides is reported, indicating that the conductivity of the electron gases can be modulated through a quantum phase transition from an insulating to a metallic state.
Abstract: We report on a large electric-field response of quasi-two-dimensional electron gases generated at interfaces in epitaxial heterostructures grown from insulating oxides. These device structures are characterized by doping layers that are spatially separated from high-mobility quasi-two-dimensional electron gases and therefore present an oxide analog to semiconducting high-electron mobility transistors. By applying a gate voltage, the conductivity of the electron gases can be modulated through a quantum phase transition from an insulating to a metallic state.
TL;DR: Cognitive training resulted in improved cognitive abilities specific to the abilities trained that continued 5 years after the initiation of the intervention, and booster training for the speed of processing group showed a significant effect on the performance-based functional measure of everyday speed ofprocessing.
Abstract: ContextCognitive training has been shown to improve cognitive abilities in older adults but the effects of cognitive training on everyday function have not been demonstrated.ObjectiveTo determine the effects of cognitive training on daily function and durability of training on cognitive abilities.Design, Setting, and ParticipantsFive-year follow-up of a randomized controlled single-blind trial with 4 treatment groups. A volunteer sample of 2832 persons (mean age, 73.6 years; 26% black), living independently in 6 US cities, was recruited from senior housing, community centers, and hospitals and clinics. The study was conducted between April 1998 and December 2004. Five-year follow-up was completed in 67% of the sample.InterventionsTen-session training for memory (verbal episodic memory), reasoning (inductive reasoning), or speed of processing (visual search and identification); 4-session booster training at 11 and 35 months after training in a random sample of those who completed training.Main Outcome MeasuresSelf-reported and performance-based measures of daily function and cognitive abilities.ResultsThe reasoning group reported significantly less difficulty in the instrumental activities of daily living (IADL) than the control group (effect size, 0.29; 99% confidence interval [CI], 0.03-0.55). Neither speed of processing training (effect size, 0.26; 99% CI, −0.002 to 0.51) nor memory training (effect size, 0.20; 99% CI, −0.06 to 0.46) had a significant effect on IADL. The booster training for the speed of processing group, but not for the other 2 groups, showed a significant effect on the performance-based functional measure of everyday speed of processing (effect size, 0.30; 99% CI, 0.08-0.52). No booster effects were seen for any of the groups for everyday problem-solving or self-reported difficulty in IADL. Each intervention maintained effects on its specific targeted cognitive ability through 5 years (memory: effect size, 0.23 [99% CI, 0.11-0.35]; reasoning: effect size, 0.26 [99% CI, 0.17-0.35]; speed of processing: effect size, 0.76 [99% CI, 0.62-0.90]). Booster training produced additional improvement with the reasoning intervention for reasoning performance (effect size, 0.28; 99% CI, 0.12-0.43) and the speed of processing intervention for speed of processing performance (effect size, 0.85; 99% CI, 0.61-1.09).ConclusionsReasoning training resulted in less functional decline in self-reported IADL. Compared with the control group, cognitive training resulted in improved cognitive abilities specific to the abilities trained that continued 5 years after the initiation of the intervention.Trial Registrationclinicaltrials.gov Identifier: NCT00298558
TL;DR: Pictures closely linked to written or spoken text can, when compared to text alone, markedly increase attention to and recall of health education information and improve comprehension when they show relationships among ideas or when they shows spatial relationships.
TL;DR: Examples from human and wildlife disease systems are reviewed to illustrate the challenges inherent in understanding the mechanisms and impacts of seasonal environmental drivers, and to highlight general insights that are relevant to other ecological interactions.
Abstract: Seasonal variations in temperature, rainfall and resource availability are ubiquitous and can exert strong pressures on population dynamics. Infectious diseases provide some of the best-studied examples of the role of seasonality in shaping population fluctuations. In this paper, we review examples from human and wildlife disease systems to illustrate the challenges inherent in understanding the mechanisms and impacts of seasonal environmental drivers. Empirical evidence points to several biologically distinct mechanisms by which seasonality can impact host-pathogen interactions, including seasonal changes in host social behaviour and contact rates, variation in encounters with infective stages in the environment, annual pulses of host births and deaths and changes in host immune defences. Mathematical models and field observations show that the strength and mechanisms of seasonality can alter the spread and persistence of infectious diseases, and that population-level responses can range from simple annual cycles to more complex multiyear fluctuations. From an applied perspective, understanding the timing and causes of seasonality offers important insights into how parasite-host systems operate, how and when parasite control measures should be applied, and how disease risks will respond to anthropogenic climate change and altered patterns of seasonality. Finally, by focusing on well-studied examples of infectious diseases, we hope to highlight general insights that are relevant to other ecological interactions.
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TL;DR: In this article, the interplay between these observations and theoretical models of the prompt gamma-ray burst and its afterglow is reviewed, and a model of the burst's origin and mechanism is proposed.
Abstract: Gamma-ray bursts are the most luminous explosions in the Universe, and their origin and mechanism are the focus of intense research and debate. More than three decades after their discovery, and after pioneering breakthroughs from space and ground experiments, their study is entering a new phase with the recently launched Swift satellite. The interplay between these observations and theoretical models of the prompt gamma-ray burst and its afterglow is reviewed.
Princeton University1, Johns Hopkins University2, California Institute of Technology3, Keele University4, University of California, Los Angeles5, Space Science Institute6, University of Arizona7, Pennsylvania State University8, University of Chicago9, Fermilab10, University of Southampton11, University of Washington12
TL;DR: In this article, the spectral energy distributions (SEDs) of 259 quasars with both Sloan Digital Sky Survey (SDS) and Spitzer photometry were analyzed.
Abstract: We present an analysis of the mid-infrared (MIR) and optical properties of type 1 (broad-line) quasars detected by the Spitzer Space Telescope. The MIR color-redshift relation is characterized to z ~ 3, with predictions to z = 7. We demonstrate how combining MIR and optical colors can yield even more efficient selection of active galactic nuclei (AGNs) than MIR or optical colors alone. Composite spectral energy distributions (SEDs) are constructed for 259 quasars with both Sloan Digital Sky Survey and Spitzer photometry, supplemented by near-IR, GALEX, VLA, and ROSAT data, where available. We discuss how the spectral diversity of quasars influences the determination of bolometric luminosities and accretion rates; assuming the mean SED can lead to errors as large as 50% for individual quasars when inferring a bolometric luminosity from an optical luminosity. Finally, we show that careful consideration of the shape of the mean quasar SED and its redshift dependence leads to a lower estimate of the fraction of reddened/obscured AGNs missed by optical surveys as compared to estimates derived from a single mean MIR to optical flux ratio.
TL;DR: In this article, an improved Hamiltonian constraint operator is introduced in loop quantum cosmology for the isotropic model with a massless scalar field and the big bang is replaced by a quantum bounce.
Abstract: An improved Hamiltonian constraint operator is introduced in loop quantum cosmology. Quantum dynamics of the spatially flat, isotropic model with a massless scalar field is then studied in detail using analytical and numerical methods. The scalar field continues to serve as ''emergent time'', the big bang is again replaced by a quantum bounce, and quantum evolution remains deterministic across the deep Planck regime. However, while with the Hamiltonian constraint used so far in loop quantum cosmology the quantum bounce can occur even at low matter densities, with the new Hamiltonian constraint it occurs only at a Planck-scale density. Thus, the new quantum dynamics retains the attractive features of current evolutions in loop quantum cosmology but, at the same time, cures their main weakness.
TL;DR: The authors proposed that overall job attitude (job satisfaction and organizational commitment) provides increasingly powerful prediction of more integrative behavioral criteria (focal performance, contextual performance, lateness, absence, and turnover combined).
Abstract: Drawing on the compatibility principle in attitude theory, we propose that overall job attitude (job satisfaction and organizational commitment) provides increasingly powerful prediction of more integrative behavioral criteria (focal performance, contextual performance, lateness, absence, and turnover combined). The principle was sustained by a combination of meta-analysis and structural equations showing better fit of unified versus diversified models of meta-analytic correlations between those criteria. Overall job attitude strongly predicted a higher-order behavioral construct, defined as desirable contributions made to one’s work role (r .59). Time-lagged data also supported this unified, attitude-engagement model.
TL;DR: The results indicate that single-walled carbon nanotube-polymer composites can be used as effective lightweight EMI shielding materials and are found to correlate with the dc conductivity.
Abstract: Single-walled carbon nanotube (SWNT)−polymer composites have been fabricated to evaluate the electromagnetic interference (EMI) shielding effectiveness (SE) of SWNTs. Our results indicate that SWNTs can be used as effective lightweight EMI shielding materials. Composites with greater than 20 dB shielding efficiency were obtained easily. EMI SE was tested in the frequency range of 10 MHz to 1.5 GHz, and the highest EMI shielding efficiency (SE) was obtained for 15 wt % SWNT, reaching 49 dB at 10 MHz and exhibiting 15−20 dB in the 500 MHz to 1.5 GHz range. The EMI SE was found to correlate with the dc conductivity, and this frequency range is found to be dominated by reflection. The effects of SWNT wall defects and aspect ratio on the EMI SE were also studied.