Showing papers by "University of Victoria published in 2010"
TL;DR: In this article, a biennial review summarizes much of particle physics using data from previous editions, plus 2158 new measurements from 551 papers, they list, evaluate and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons.
Abstract: This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2158 new measurements from 551 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. Among the 108 reviews are many that are new or heavily revised including those on neutrino mass, mixing, and oscillations, QCD, top quark, CKM quark-mixing matrix, V-ud & V-us, V-cb & V-ub, fragmentation functions, particle detectors for accelerator and non-accelerator physics, magnetic monopoles, cosmological parameters, and big bang cosmology.
2,788 citations
TL;DR: Place attachment has been researched quite broadly, and so has been defined in a variety of ways as discussed by the authors, and various definitions of the concept are reviewed and synthesized into a three-dimensional, person-process-place organizing framework.
1,658 citations
Stockholm University1, University of California, Berkeley2, Lawrence Berkeley National Laboratory3, Pierre-and-Marie-Curie University4, Colorado College5, University of Colorado Boulder6, University of Utah7, Space Telescope Science Institute8, University of Tokyo9, University of Victoria10, Carnegie Institution for Science11, INAF12, University of Oxford13, University of California, Santa Barbara14, Las Cumbres Observatory Global Telescope Network15, Drexel University16, University of Bonn17, Japan Society for the Promotion of Science18, University of Barcelona19, Texas A&M University20, University of Pittsburgh21
TL;DR: Kowalski et al. as mentioned in this paper reported on work to increase the number of well-measured Type Ia supernovae (SNe Ia) at high redshifts.
Abstract: We report on work to increase the number of well-measured Type Ia supernovae (SNe Ia) at high redshifts. Light curves, including high signal-to-noise HST data, and spectra of six SNe Ia that were discovered during 2001 are presented. Additionally, for the two SNe with z > 1, we present groundbased J-band photometry from Gemini and the VLT. These are among the most distant SNe Ia for which ground based near-IR observations have been obtained. We add these six SNe Ia together with other data sets that have recently become available in the literature to the Union compilation (Kowalski et al. 2008). We have made a number of refinements to the Union analysis chain, the most important ones being the refitting of all light curves with the SALT2 fitter and an improved handling of systematic errors. We call this new compilation, consisting of 557 supernovae, the Union2
1,424 citations
TL;DR: In this paper, the authors provided an up-to-date assessment of global mercury emissions from anthropogenic and natural sources, including re-emission processes and primary emissions from natural reservoirs.
Abstract: . This paper provides an up-to-date assessment of global mercury emissions from anthropogenic and natural sources. On an annual basis, natural sources account for 5207 Mg of mercury released to the global atmosphere, including the contribution from re-emission processes, which are emissions of previously deposited mercury originating from anthropogenic and natural sources, and primary emissions from natural reservoirs. Anthropogenic sources, which include a large number of industrial point sources, are estimated to account for 2320 Mg of mercury emitted annually. The major contributions are from fossil-fuel fired power plants (810 Mg yr−1), artisanal small scale gold mining (400 Mg yr−1), non-ferrous metals manufacturing (310 Mg yr−1), cement production (236 Mg yr−1), waste disposal (187 Mg yr−1) and caustic soda production (163 Mg yr−1). Therefore, our current estimate of global mercury emissions suggests that the overall contribution from natural sources (primary emissions + re-emissions) and anthropogenic sources is nearly 7527 Mg per year, the uncertainty associated with these estimates are related to the typology of emission sources and source regions.
1,240 citations
15 Jul 2010
1,050 citations
TL;DR: The SHINE toolbox for MATLAB features functions for specifying the (rotational average of the) Fourier amplitude spectra, for normalizing and scaling mean luminance and contrast, and for exact histogram specification optimized for perceptual visual quality.
Abstract: Visual perception can be influenced by top-down processes related to the observer’s goals and expectations, as well as by bottom-up processes related to low-level stimulus attributes, such as luminance, contrast, and spatial frequency. When using different physical stimuli across psychological conditions, one faces the problem of disentangling the contributions of low- and high-level factors. Here, we make available the SHINE (spectrum, histogram, and intensity normalization and equalization) toolbox for MATLAB, which we have found useful for controlling a number of image properties separately or simultaneously. The toolbox features functions for specifying the (rotational average of the) Fourier amplitude spectra, for normalizing and scaling mean luminance and contrast, and for exact histogram specification optimized for perceptual visual quality. SHINE can thus be employed for parametrically modifying a number of image properties or for equating them across stimuli to minimize potential low-level confounds in studies on higher level processes.
844 citations
TL;DR: 3D radiation dose distribution in polymer gel dosimeters may be imaged using magnetic resonance imaging (MRI), optical-computerized tomography (optical-CT), x-ray CT or ultrasound, and clinical dosimetry applications of polymer gel Dosimetry are presented.
Abstract: Polymer gel dosimeters are fabricated from radiation sensitive chemicals which, upon irradiation, polymerize as a function of the absorbed radiation dose. These gel dosimeters, with the capacity to uniquely record the radiation dose distribution in three-dimensions (3D), have specific advantages when compared to one-dimensional dosimeters, such as ion chambers, and two-dimensional dosimeters, such as film. These advantages are particularly significant in dosimetry situations where steep dose gradients exist such as in intensity-modulated radiation therapy (IMRT) and stereotactic radiosurgery. Polymer gel dosimeters also have specific advantages for brachytherapy dosimetry. Potential dosimetry applications include those for low-energy x-rays, high-linear energy transfer (LET) and proton therapy, radionuclide and boron capture neutron therapy dosimetries. These 3D dosimeters are radiologically soft-tissue equivalent with properties that may be modified depending on the application. The 3D radiation dose distribution in polymer gel dosimeters may be imaged using magnetic resonance imaging (MRI), optical-computerized tomography (optical-CT), x-ray CT or ultrasound. The fundamental science underpinning polymer gel dosimetry is reviewed along with the various evaluation techniques. Clinical dosimetry applications of polymer gel dosimetry are also presented.
784 citations
TL;DR: Using this setup, luminescence efficiency data is successfully acquired for lanthanide-doped upconverting nanoparticles and quantum yields in the range of 0.005% to 0.3% were measured for several NaYF(4).
Abstract: In this communication we describe a technique for measuring the absolute quantum yields (QYs) of upconverting nanomaterials based on the use of a commercially available fluorimeter and an integrating sphere. Using this setup, we have successfully acquired luminescence efficiency data (pump laser, absorbed pump, and visible emitted intensities) for lanthanide-doped upconverting nanoparticles. QYs in the range of 0.005% to 0.3% were measured for several NaYF4: 2% Er3+, 20% Yb3+ nanoparticles with particle sizes ranging from 10 to 100 nm while a QY of 3% was measured for a bulk sample.
781 citations
TL;DR: In this paper, the structure of CDM halos using a suite of N-body simulations of un-precedented numerical resolution is studied. But the results of the analysis are limited to a single dark matter halo using 4.4 billion particles, of which 1.1 billion end up within the virial radius.
Abstract: We study the structure ofCDM halos using a suite of N-body simulations of un- precedented numerical resolution. The Aquarius Project follows the formation of 6 different galaxy-sized halos simulated several times at varying numerical resolution, allowing numerical convergence to be assessed directly. The highest resolution sim- ulation represents a single dark matter halo using 4.4 billion particles, of which 1.1 billion end up within the virial radius. Our analysis confirms that the mass pro- file ofCDM halos deviates slightly but systematically from the form proposed by Navarro, Frenk & White. The spherically-averaged density profile becomes progres- sively shallower inwards and, at the innermost resolved radius, the logarithmic slope isdln�/dlnr < � 1, convincingly ruling out recent claims of a steep � / r 1.2 central cusp. The radial dependence of is well approximated by a power-law, / r � (the Einasto profile). The shape parameter, �, varies slightly but significantly from halo to halo, implying that the mass profiles ofCDM halos are not strictly universal: different halos cannot, in general, be rescaled to look exactly alike. Departures from similarity are also seen in velocity dispersion profiles and correlate with those in density profiles so as to preserve a power-law form for the spherically averaged pseudo-phase- space density, �/� 3 / r 1.875 . The index here is identical to that of Bertschinger's similarity solution for self-similar infall onto a point mass from an otherwise uniform Einstein-de Sitter Universe. The origin of this striking behaviour is unclear, but its robustness suggests that it reflects a fundamental structural property ofCDM halos. Our conclusions are reliable down to radii below 0.4% of the virial radius, providing well-defined predictions for halo structure when baryonic effects are neglected, and thus an instructive theoretical template against which the modifications induced by the baryonic components of real galaxies can be judged.
760 citations
TL;DR: The simulation results show that modified grey models have higher performances not only on model fitting but also on forecasting, and the modified GM(1,1) using Fourier series in time is the best in model fitting and forecasting.
Abstract: Being able to forecast time series accurately has been quite a popular subject for researchers both in the past and at present. However, the lack of ability of conventional analysis methods to forecast time series that are not smooth leads the scientists and researchers to resort to various forecasting models that have different mathematical backgrounds, such as artificial neural networks, fuzzy predictors, evolutionary and genetic algorithms. In this paper, the accuracies of different grey models such as GM(1,1), Grey Verhulst model, modified grey models using Fourier Series is investigated. Highly noisy data, the United States dollar to Euro parity between the dates 01.01.2005 and 30.12.2007, are used to compare the performances of the different models. The simulation results show that modified grey models have higher performances not only on model fitting but also on forecasting. Among these grey models, the modified GM(1,1) using Fourier series in time is the best in model fitting and forecasting.
720 citations
TL;DR: Modules for Experiments in Stellar Astrophysics (MESA) as mentioned in this paper is a suite of open source libraries for a wide range of applications in computational stellar astrophysics, including advanced evolutionary phases.
Abstract: Stellar physics and evolution calculations enable a broad range of research in astrophysics. Modules for Experiments in Stellar Astrophysics (MESA) is a suite of open source libraries for a wide range of applications in computational stellar astrophysics. A newly designed 1-D stellar evolution module, MESA star, combines many of the numerical and physics modules for simulations of a wide range of stellar evolution scenarios ranging from very-low mass to massive stars, including advanced evolutionary phases. MESA star solves the fully coupled structure and composition equations simultaneously. It uses adaptive mesh refinement and sophisticated timestep controls, and supports shared memory parallelism based on OpenMP. Independently usable modules provide equation of state, opacity, nuclear reaction rates, and atmosphere boundary conditions. Each module is constructed as a separate Fortran 95 library with its own public interface. Examples include comparisons to other codes and show evolutionary tracks of very low mass stars, brown dwarfs, and gas giant planets; the complete evolution of a 1 Msun star from the pre-main sequence to a cooling white dwarf; the Solar sound speed profile; the evolution of intermediate mass stars through the thermal pulses on the He-shell burning AGB phase; the interior structure of slowly pulsating B Stars and Beta Cepheids; evolutionary tracks of massive stars from the pre-main sequence to the onset of core collapse; stars undergoing Roche lobe overflow; and accretion onto a neutron star. Instructions for downloading and installing MESA can be found on the project web site (this http URL).
TL;DR: In this article, the authors used the ATLAS detector to detect dijet asymmetry in the collisions of lead ions at the Large Hadron Collider and found that the transverse energies of dijets in opposite hemispheres become systematically more unbalanced with increasing event centrality, leading to a large number of events which contain highly asymmetric di jets.
Abstract: By using the ATLAS detector, observations have been made of a centrality-dependent dijet asymmetry in the collisions of lead ions at the Large Hadron Collider. In a sample of lead-lead events with a per-nucleon center of mass energy of 2.76 TeV, selected with a minimum bias trigger, jets are reconstructed in fine-grained, longitudinally segmented electromagnetic and hadronic calorimeters. The transverse energies of dijets in opposite hemispheres are observed to become systematically more unbalanced with increasing event centrality leading to a large number of events which contain highly asymmetric dijets. This is the first observation of an enhancement of events with such large dijet asymmetries, not observed in proton-proton collisions, which may point to an interpretation in terms of strong jet energy loss in a hot, dense medium.
TL;DR: In this article, a suite of high-resolution N-body simulations of individual dark matter haloes is presented, which is based on the Aquarius project, and the authors find that accreted stellar haloes are assembled between 1 < z < 7 from less than five significant progenitors.
Abstract: We present six simulations of galactic stellar haloes formed by the tidal disruption of accreted dwarf galaxies in a fully cosmological setting. Our model is based on the Aquarius project, a suite of high-resolution N-body simulations of individual dark matter haloes. We tag subsets of particles in these simulations with stellar populations predicted by the galform semi-analytic model. Our method self-consistently tracks the dynamical evolution and disruption of satellites from high redshift. The luminosity function (LF) and structural properties of surviving satellites, which agree well with observations, suggest that this technique is appropriate. We find that accreted stellar haloes are assembled between 1 < z < 7 from less than five significant progenitors. These progenitors are old, metal-rich satellites with stellar masses similar to the brightest Milky Way dwarf spheroidals (10^(7)–10^(8) M_⊙). In contrast to previous stellar halo simulations, we find that several of these major contributors survive as self-bound systems to the present day. Both the number of these significant progenitors and their infall times are inherently stochastic. This results in great diversity among our stellar haloes, which amplifies small differences between the formation histories of their dark halo hosts. The masses (~10^(8)–10^(9) M_⊙) and density/surface-brightness profiles of the stellar haloes (from 10 to 100 kpc) are consistent with expectations from the Milky Way and M31. Each halo has a complex structure, consisting of well-mixed components, tidal streams, shells and other subcomponents. This structure is not adequately described by smooth models. The central regions (<10 kpc) of our haloes are highly prolate (c/a ~ 0.3), although we find one example of a massive accreted thick disc. Metallicity gradients in our haloes are typically significant only where the halo is built from a small number of satellites. We contrast the ages and metallicities of halo stars with surviving satellites, finding broad agreement with recent observations.
Pierre-and-Marie-Curie University1, University of Oxford2, University of Colorado Boulder3, University of Toronto4, University of Paris5, Centre national de la recherche scientifique6, Aix-Marseille University7, INAF8, Las Cumbres Observatory Global Telescope Network9, University of California, Santa Barbara10, Defence Research and Development Canada11, University of Victoria12, California Institute of Technology13, Centra14, Lawrence Berkeley National Laboratory15
TL;DR: In this paper, photometric properties and distance measurements of 252 high redshift Type Ia supernovae (0.15 < z < 1.1) were presented and their multi-colour light curves measured using the MegaPrime/MegaCam instrument at the Canada-France-Hawaii Telescope (CFHT).
Abstract: Aims. We present photometric properties and distance measurements of 252 high redshift Type Ia supernovae (0.15 < z < 1.1)
discovered during the first three years of the Supernova Legacy Survey (SNLS). These events were detected and their multi-colour
light curves measured using the MegaPrime/MegaCam instrument at the Canada-France-Hawaii Telescope (CFHT), by repeatedly
imaging four one-square degree fields in four bands. Follow-up spectroscopy was performed at the VLT, Gemini and Keck telescopes
to confirm the nature of the supernovae and to measure their redshifts.
Methods. Systematic uncertainties arising from light curve modeling are studied, making use of two techniques to derive the peak
magnitude, shape and colour of the supernovae, and taking advantage of a precise calibration of the SNLS fields.
Results. A flat ΛCDM cosmological fit to 231 SNLS high redshift type Ia supernovae alone gives Ω_M = 0.211 ± 0.034(stat) ±
0.069(sys). The dominant systematic uncertainty comes from uncertainties in the photometric calibration. Systematic uncertainties
from light curve fitters come next with a total contribution of ± 0.026 on Ω_M. No clear evidence is found for a possible evolution of
the slope (β) of the colour-luminosity relation with redshift.
TL;DR: In this paper, a community sample of residents from two proximate towns with different environmental reputations reported the strength of their civic and natural place attachment, their performance of various pro-environmental behaviors, and a number of sociodemographic characteristics.
TL;DR: Two interesting subclasses of normalized analytic and univalent functions in the open unit disk whose inverse has univalently analytic continuation to U is introduced and investigated.
TL;DR: In this article, the authors performed searches for lepton-flavor-violating decays of a tau lepton to a lighter mass lepton and a photon with the entire data set of (963 +/- 7) x 10(6) tau decays collected by the BABAR detector near the Y(4S), Y(3S) and Y(2S) resonances.
Abstract: Searches for lepton-flavor-violating decays of a tau lepton to a lighter mass lepton and a photon have been performed with the entire data set of (963 +/- 7) x 10(6) tau decays collected by the BABAR detector near the Y(4S), Y(3S) and Y(2S) resonances. The searches yield no evidence of signals and we set upper limits on the branching fractions of B(tau(+/-) -> e(+/-)gamma) mu(+/-)gamma) < 4.4 X 10(-8) at 90% confidence level.
TL;DR: It is demonstrated that a maternally transmitted bacterium, Spiroplasma, protects Drosophila neotestacea against the sterilizing effects of a parasitic nematode, both in the laboratory and the field, demonstrating the profound and potentially rapid effects of defensive symbionts.
Abstract: Fruit flies, like most animals, are vulnerable to infection by a range of organisms, which, in co-infections, can interact with sometimes surprising effects. Jaenike et al. (p. [212][1]) discovered that a species of Spiroplasma bacterium that is sometimes found in flies, and that is transmitted from mother to offspring, protects its host from the effects of a nematode worm parasite, Howardula aoronymphium . The worm sterilizes the female flies and shortens their lives, but when flies were experimentally infected with Spiroplasma , their fertility was rescued. Similarly, in wild populations of fruit flies infected with worms, those also infected with Spiroplasma had more eggs in their ovaries. The bacterium inhibits the growth of the adult female worms, but such is the advantage of this bacterial infection in offsetting the burden of nematodes on reproductive fitness, Spiroplasma appears to be spreading rapidly through populations of fruit flies in North America.
[1]: /lookup/volpage/329/212?iss=5988
University of Essex1, University of Cambridge2, International Center for Tropical Agriculture3, United States Department of Agriculture4, University of Wisconsin-Madison5, CABI6, Department for International Development7, University of East Anglia8, University of Otago9, Agricultural & Applied Economics Association10, Agriculture and Horticulture Development Board11, University of Bern12, Bangor University13, University of Matanzas14, University of Oxford15, Chiang Mai University16, University of Sussex17, Secretariat of the Pacific Community18, Millennium Institute19, CGIAR20, Fara21, Ohio State University22, City University London23, International Union for Conservation of Nature and Natural Resources24, Department for Business, Innovation and Skills25, International Water Management Institute26, Wageningen University and Research Centre27, Indian Institute of Science28, University of the Philippines Los Baños29, University College Cork30, Fujian Normal University31, South China Agricultural University32, World Agroforestry Centre33, University of Aberdeen34, University of Colorado Boulder35, University of Victoria36, University of California, Davis37, International Institute for Environment and Development38, United Nations39, Royal Society for the Protection of Birds40
TL;DR: The UK Government's Foresight Global Food and Farming Futures project as mentioned in this paper aims to improve dialogue and understanding between agricultural research and policy by identifying the 100 most important questions for global agriculture.
Abstract: Despite a significant growth in food production over the past half-century, one of the most important challenges facing society today is how to feed an expected population of some nine billion by the middle of the 20th century. To meet the expected demand for food without significant increases in prices, it has been estimated that we need to produce 70-100 per cent more food, in light of the growing impacts of climate change, concerns over energy security, regional dietary shifts and the Millennium Development target of halving world poverty and hunger by 2015. The goal for the agricultural sector is no longer simply to maximize productivity, but to optimize across a far more complex landscape of production, rural development, environmental, social justice and food consumption outcomes. However, there remain significant challenges to developing national and international policies that support the wide emergence of more sustainable forms of land use and efficient agricultural production. The lack of information flow between scientists, practitioners and policy makers is known to exacerbate the difficulties, despite increased emphasis upon evidence-based policy. In this paper, we seek to improve dialogue and understanding between agricultural research and policy by identifying the 100 most important questions for global agriculture. These have been compiled using a horizon-scanning approach with leading experts and representatives of major agricultural organizations worldwide. The aim is to use sound scientific evidence to inform decision making and guide policy makers in the future direction of agricultural research priorities and policy support. If addressed, we anticipate that these questions will have a significant impact on global agricultural practices worldwide, while improving the synergy between agricultural policy, practice and research. This research forms part of the UK Government's Foresight Global Food and Farming Futures project.
TL;DR: In this article, the median color difference between the horizontal branch and the red giant branch was measured from HST Advanced Camera for Surveys (ACS) photometry of 60 GCs within approx20 kpc of the Galactic center.
Abstract: The horizontal branch (HB) morphology of globular clusters (GCs) is most strongly influenced by metallicity. The second parameter phenomenon, first described in the 1960s, acknowledges that metallicity alone is not enough to describe the HB morphology of all GCs. In particular, astronomers noticed that the outer Galactic halo contains GCs with redder HBs at a given metallicity than are found inside the solar circle. Thus, at least a second parameter was required to characterize HB morphology. While the term 'second parameter' has since come to be used in a broader context, its identity with respect to the original problem has not been conclusively determined. Here we analyze the median color difference between the HB and the red giant branch, hereafter denoted as DELTA(V - I), measured from Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) photometry of 60 GCs within approx20 kpc of the Galactic center. Analysis of this homogeneous data set reveals that, after the influence of metallicity has been removed from the data, the correlation between DELTA(V - I) and age is stronger than that of any other parameter considered. Expanding the sample to include HST ACS and Wide Field Planetary Camera 2 photometry of the sixmore » most distant Galactic GCs lends additional support to the correlation between DELTA(V - I) and age. This result is robust with respect to the adopted metallicity scale and the method of age determination, but must bear the caveat that high-quality, detailed abundance information is not available for a significant fraction of the sample. Furthermore, when a subset of GCs with similar metallicities and ages is considered, a correlation between DELTA(V - I) and central luminosity density is exposed. With respect to the existence of GCs with anomalously red HBs at a given metallicity, we conclude that age is the second parameter and central density is most likely the third. Important problems related to HB morphology in GCs, notably multi-modal distributions and faint blue tails, remain to be explained.« less
University of Oxford1, University of Colorado Boulder2, University of California, Santa Barbara3, Las Cumbres Observatory Global Telescope Network4, California Institute of Technology5, Pierre-and-Marie-Curie University6, University of Paris7, University of Toronto8, Aix-Marseille University9, INAF10, DSM11, Defence Research and Development Canada12, University of Victoria13, Centre national de la recherche scientifique14, Lawrence Berkeley National Laboratory15, University of California, Berkeley16
TL;DR: In this paper, the authors used the Supernova Legacy Survey (SNLS) and other data to show that there is an additional dependence on the global characteristics of their host galaxies: events of the same light-curve shape and colour are, on average, 0.08mag (~4.0sigma) brighter in massive host galaxies (presumably metal-rich) and galaxies with low specific star-formation rates (sSFR).
Abstract: (Abridged) Precision cosmology with Type Ia supernovae (SNe Ia) makes use of the fact that SN Ia luminosities depend on their light-curve shapes and colours. Using Supernova Legacy Survey (SNLS) and other data, we show that there is an additional dependence on the global characteristics of their host galaxies: events of the same light-curve shape and colour are, on average, 0.08mag (~4.0sigma) brighter in massive host galaxies (presumably metal-rich) and galaxies with low specific star-formation rates (sSFR). SNe Ia in galaxies with a low sSFR also have a smaller slope ("beta") between their luminosities and colours with ~2.7sigma significance, and a smaller scatter on SN Ia Hubble diagrams (at 95% confidence), though the significance of these effects is dependent on the reddest SNe. SN Ia colours are similar between low-mass and high-mass hosts, leading us to interpret their luminosity differences as an intrinsic property of the SNe and not of some external factor such as dust. If the host stellar mass is interpreted as a metallicity indicator, the luminosity trends are in qualitative agreement with theoretical predictions. We show that the average stellar mass, and therefore the average metallicity, of our SN Ia host galaxies decreases with redshift. The SN Ia luminosity differences consequently introduce a systematic error in cosmological analyses, comparable to the current statistical uncertainties on parameters such as w. We show that the use of two SN Ia absolute magnitudes, one for events in high-mass (metal-rich) galaxies, and one for events in low-mass (metal-poor) galaxies, adequately corrects for the differences. Cosmological fits incorporating these terms give a significant reduction in chi^2 (3.8-4.5sigma). We conclude that future SN Ia cosmological analyses should use a correction of this (or similar) form to control demographic shifts in the galaxy population.
TL;DR: The PEG-phosphate coated upconverting NPs were used to image a line of ovarian cancer cells (CaOV3) to demonstrate their promise in biological application and overcome the upconversion intensity problem in aqueous environments.
Abstract: We present a technique for the replacement of oleate with a PEG−phosphate ligand [PEG = poly(ethylene glycol)] as an efficient method for the generation of water-dispersible NaYF4 nanoparticles (NPs). The PEG−phosphate ligands are shown to exchange with the original oleate ligands on the surface of the NPs, resulting in water-dispersible NPs. The upconversion intensity of the NPs in aqueous environments was found to be severely quenched when compared to the original NPs in organic solvents. This is attributed to an increase in the multiphonon relaxations of the lanthanide excited state in aqueous environments due to high energy vibrational modes of water molecules. This problem could be overcome partially by the synthesis of core/shell NPs which demonstrated improved photophysical properties in water over the original core NPs. The PEG−phosphate coated upconverting NPs were then used to image a line of ovarian cancer cells (CaOV3) to demonstrate their promise in biological application.
TL;DR: In this article, a dual-bridge series resonant dc/dc converter with high frequency isolation is analyzed with two simple modified ac equivalent circuit analysis methods for both voltage source load and resistive load.
Abstract: Bidirectional dual-bridge dc/dc converter with high frequency isolation is gaining more attentions in renewable energy system due to small size and high-power density. In this paper, a dual-bridge series resonant dc/dc converter is analyzed with two simple modified ac equivalent circuit analysis methods for both voltage source load and resistive load. In both methods, only fundamental components of voltages and currents are considered. All the switches may work in either zero-voltage-switching or zero-current-switching for a wide variation of voltage gain, which is important in renewable energy generation. It is also shown in the second method that the load side circuit could be represented with an equivalent impedance. The polarity of cosine value of this equivalent impedance angle reveals the power flow direction. The analysis is verified with computer simulation results. Experimental data based on a 200 W prototype circuit is included for validation purpose.
TL;DR: In this article, the authors conceptualized and operationalized alliance management capability and developed a second-order construct to capture the degree to which organizations possess relevant management routines that enable them to effectively manage their portfolio of strategic alliances.
Harvard University1, University of Exeter2, University of Cambridge3, University of Massachusetts Amherst4, University of Toledo5, University of Texas at Austin6, California Institute of Technology7, Herzberg Institute of Astrophysics8, University of Victoria9, University of Hawaii at Manoa10, European Space Agency11, Dublin Institute for Advanced Studies12, University of New South Wales13
TL;DR: In this article, a global study of low mass, young stellar object (YSO) surface densities in nearby star forming regions based on a comprehensive collection of Spitzer Space Telescope surveys is presented.
Abstract: We present a global study of low mass, young stellar object (YSO) surface densities (�) in nearby (< 500 pc) star forming regions based on a comprehensive collection of Spitzer Space Telescope surveys. We show that the distribution of YSO surface densities in the solar neighbourhood is a smooth distribution, being adequately described by a lognormal function from a few to 10 3 YSOs per pc 2 , with a peak at � 22 stars pc
TL;DR: A comprehensive review of quantitative research (1998—2008) in this area, utilizing a systematic approach targeting studies on family caregivers, home settings, and an identified palliative phase of care suggests the need for knowledge regarding: family caregiving for patients with non-malignant terminal conditions and whether needs and outcomes differ between family caregivers at the end of life and comparison groups.
Abstract: The changing context of palliative care over the last decade highlights the importance of recent research on home-based family caregiving at the end of life. This article reports on a comprehensive review of quantitative research (1998—2008) in this area, utilizing a systematic approach targeting studies on family caregivers, home settings, and an identified palliative phase of care (n = 129). Methodological challenges were identified, including: small, non-random, convenience samples; reliance on descriptive and bivariate analyses; and a dearth of longitudinal research. Robust evidence regarding causal relationships between predictor variables and carer outcomes is lacking. Findings suggest the need for knowledge regarding: family caregiving for patients with non-malignant terminal conditions; whether needs and outcomes differ between family caregivers at the end of life and comparison groups; and caregiver outcomes in bereavement. Clear definitions of ‘family caregiving’, ‘end of life’, and ‘needs’ are ...
TL;DR: This paper reviewed the evidence showing significant human-induced changes in regional temperatures, and for the effects of external forcings on changes in the hydrological cycle, the cryosphere, circulation changes, oceanic changes, and changes in extremes.
Abstract: The Intergovernmental Panel on Climate Change fourth assessment report, published in 2007 came to a more confident assessment of the causes of global temperature change than previous reports and concluded that ‘it is likely that there has been significant anthropogenic warming over the past 50 years averaged over each continent except Antarctica.’ Since then, warming over Antarctica has also been attributed to human influence, and further evidence has accumulated attributing a much wider range of climate changes to human activities. Such changes are broadly consistent with theoretical understanding, and climate model simulations, of how the planet is expected to respond. This paper reviews this evidence from a regional perspective to reflect a growing interest in understanding the regional effects of climate change, which can differ markedly across the globe. We set out the methodological basis for detection and attribution and discuss the spatial scales on which it is possible to make robust attribution statements. We review the evidence showing significant human-induced changes in regional temperatures, and for the effects of external forcings on changes in the hydrological cycle, the cryosphere, circulation changes, oceanic changes, and changes in extremes. We then discuss future challenges for the science of attribution. To better assess the pace of change, and to understand more about the regional changes to which societies need to adapt, we will need to refine our understanding of the effects of external forcing and internal variability
TL;DR: In this article, the authors presented an updated nucleosynthesis calculations for a 25 M? star of Population I (solar metallicity) in convective He-burning core and convective C-burning shell conditions.
Abstract: The slow neutron capture process in massive stars (weak s process) produces most of the s-process isotopes between iron and strontium. Neutrons are provided by the 22Ne(?,n)25Mg reaction, which is activated at the end of the convective He-burning core and in the subsequent convective C-burning shell. The s-process-rich material in the supernova ejecta carries the signature of these two phases. In the past years, new measurements of neutron capture cross sections of isotopes beyond iron significantly changed the predicted weak s-process distribution. The reason is that the variation of the Maxwellian-averaged cross sections (MACS) is propagated to heavier isotopes along the s path. In the light of these results, we present updated nucleosynthesis calculations for a 25 M ? star of Population I (solar metallicity) in convective He-burning core and convective C-burning shell conditions. In comparison with previous simulations based on the Bao et?al. compilation, the new measurement of neutron capture cross sections leads to an increase of s-process yields from nickel up to selenium. The variation of the cross section of one isotope along the s-process path is propagated to heavier isotopes, where the propagation efficiency is higher for low cross sections. New 74Ge, 75As, and 78Se MACS result in a higher production of germanium, arsenic, and selenium, thereby reducing the s-process yields of heavier elements by propagation. Results are reported for the He core and for the C shell. In shell C-burning, the s-process nucleosynthesis is more uncertain than in the He core, due to higher MACS uncertainties at higher temperatures. We also analyze the impact of using the new lower solar abundances for CNO isotopes on the s-process predictions, where CNO is the source of 22Ne, and we show that beyond Zn this is affecting the s-process yields more than nuclear or stellar model uncertainties considered in this paper. In particular, using the new updated initial composition, we obtain a high s-process production (overproduction higher than 16O, ~100) for Cu, Ga, Ge, and As. Using the older abundances by Anders & Grevesse, also Se, Br, Kr, and Rb are efficiently produced. Our results have important implications in explaining the origin of copper in the solar abundance distribution, pointing to a prevailing contribution from the weak s-process in agreement with spectroscopic observations and Galactic chemical evolution calculations. Because of the improvement due to the new MACS for nickel and copper isotopes, the nucleosynthesis of copper is less affected by nuclear uncertainties compared to heavier s-process elements. An experimental determination of the 63Ni MACS is required for a further improvement of the abundance prediction of copper. The available spectroscopic observations of germanium and gallium in stars are also discussed, where most of the cosmic abundances of these elements derives from the s-process in massive stars.
McGill University1, Courant Institute of Mathematical Sciences2, Earth System Research Laboratory3, Cooperative Institute for Research in Environmental Sciences4, Columbia University5, University of Victoria6, Pusan National University7, German Aerospace Center8, University of Toronto9, Johns Hopkins University10, National Institute for Environmental Studies11, Geophysical Fluid Dynamics Laboratory12, Max Planck Society13, Centre national de la recherche scientifique14, University of Cambridge15, Met Office16, University of Leeds17, Goddard Space Flight Center18, National Center for Atmospheric Research19, National Institute of Water and Atmospheric Research20, Environment Canada21, ETH Zurich22
TL;DR: In this article, the impact of stratospheric ozone on the tropospheric general circulation of the Southern Hemisphere (SH) is examined with a set of chemistry-climate models participating in the Stratospheric Processes and their Role in Climate (SPARC)/Chemistry-Climate Model Validation project phase 2 (CCMVal-2).
Abstract: The impact of stratospheric ozone on the tropospheric general circulation of the Southern Hemisphere (SH) is examined with a set of chemistry-climate models participating in the Stratospheric Processes and their Role in Climate (SPARC)/Chemistry-Climate Model Validation project phase 2 (CCMVal-2). Model integrations of both the past and future climates reveal the crucial role of stratospheric ozone in driving SH circulation change: stronger ozone depletion in late spring generally leads to greater poleward displacement and intensification of the tropospheric midlatitude jet, and greater expansion of the SH Hadley cell in the summer. These circulation changes are systematic as poleward displacement of the jet is typically accompanied by intensification of the jet and expansion of the Hadley cell. Overall results are compared with coupled models participating in the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4), and possible mechanisms are discussed. While the tropospheric circulation response appears quasi-linearly related to stratospheric ozone changes, the quantitative response to a given forcing varies considerably from one model to another. This scatter partly results from differences in model climatology. It is shown that poleward intensification of the westerly jet is generally stronger in models whose climatological jet is biased toward lower latitudes. This result is discussed in the context of quasi-geostrophic zonal mean dynamics.
TL;DR: Findings indicate that the built environment has a significant influence on healthy travel decisions, and spatial context is important, and future research should explicitly consider relevant spatial zones when investigating the relationship between physical activity and urban form.
Abstract: A growing body of evidence links the built environment to physical activity levels, health outcomes, and transportation behaviors. However, little of this research has focused on cycling, a sustainable transportation option with great potential for growth in North America. This study examines associations between decisions to bicycle (versus drive) and the built environment, with explicit consideration of three different spatial zones that may be relevant in travel behavior: trip origins, trip destinations, and along the route between. We analyzed 3,280 utilitarian bicycle and car trips in Metro Vancouver, Canada made by 1,902 adults, including both current and potential cyclists. Objective measures were developed for built environment characteristics related to the physical environment, land use patterns, the road network, and bicycle-specific facilities. Multilevel logistic regression was used to model the likelihood that a trip was made by bicycle, adjusting for trip distance and personal demographics. Separate models were constructed for each spatial zone, and a global model examined the relative influence of the three zones. In total, 31% (1,023 out of 3,280) of trips were made by bicycle. Increased odds of bicycling were associated with less hilliness; higher intersection density; less highways and arterials; presence of bicycle signage, traffic calming, and cyclist-activated traffic lights; more neighborhood commercial, educational, and industrial land uses; greater land use mix; and higher population density. Different factors were important within each spatial zone. Overall, the characteristics of routes were more influential than origin or destination characteristics. These findings indicate that the built environment has a significant influence on healthy travel decisions, and spatial context is important. Future research should explicitly consider relevant spatial zones when investigating the relationship between physical activity and urban form.