389 research outputs found

    Extended H? emission line sources from UWISH2

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    We present the extended source catalogue for the UKIRT Wide Field Infrared Survey for H2 (UWISH2). The survey is unbiased along the inner Galactic Plane from l ? 357° to l ? 65° and |b| ? 1.5° and covers 209 deg2. A further 42.0 and 35.5 deg2 of high dust column density regions have been targeted in Cygnus and Auriga. We have identified 33 200 individual extended H2 features. They have been classified to be associated with about 700 groups of jets and outflows, 284 individual (candidate) planetary nebulae, 30 supernova remnants and about 1300 photodissociation regions. We find a clear decline of star formation activity (traced by H2 emission from jets and photodissociation regions) with increasing distance from the Galactic Centre. About 60 per cent of the detected candidate planetary nebulae have no known counterpart and 25 per cent of all supernova remnants have detectable H2 emission associated with them

    Dark gas in the solar neighnorhood from extinction data

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    When modeling infrared or gamma-ray data as a linear combination of observed gas tracers, excess emission has been detected compared to expectations from known neutral and atomic gas as traced by HI and CO measurements, respectively. This excess might correspond to an additional gas component. This so-called "dark gas" (DG) has been observed in our Galaxy, as well as the Magellanic Clouds. For the first time, we investigate the correlation between visible extinction (Av) data and gas tracers on large scales in the solar neighborhood. Our work focuses on both the solar neighborhood (|b|>10\degr), and the inner and outer Galaxy, as well as on four individual regions: Taurus, Orion, Cepheus-Polaris and Aquila-Ophiuchus. Thanks to the recent production of an all-sky Av map, we first perform the correlation between Av and both HI and CO emission over the most diffuse regions, to derive the optimal (Av/NH)^(ref) ratio. We then iterate the analysis over the entire regions to estimate the CO-to-H2 conversion factor as well as the DG mass fraction. The average extinction to gas column-density ratio in the solar neighborhood is found to be (Av/NH)^(ref)=6.53 10^(-22) mag. cm^2, with significant differences between the inner and outer Galaxy. We derive an average XCO value of 1.67 10^(20) H2 cm^(-2)/(K km s^(-1)). In the solar neighborhood, the gas mass in the dark component is found to be 19% relative to that in the atomic component and 164% relative to the one traced by CO. These results are compatible with the recent analysis using Planck data within the uncertainties of our measurements. We estimate the ratio of dark gas to total molecular gas to be 0.62 in the solar neighborhood. The HI-to-H2 and H2-to-CO transitions appear for Av \simeq0.2 mag and Av1.5\simeq1.5 mag, respectively, in agreement with theoretical models of dark-H2 gas.Comment: 9 pages, 4 figures, 1 table. Accepted for publication in A&A (in press

    Targeting Conservation Investments in Heterogeneous Landscapes: A distance function approach and application to watershed management

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    To achieve a given level of an environmental amenity at least cost, decision-makers must integrate information about spatially variable biophysical and economic conditions. Although the biophysical attributes that contribute to supplying an environmental amenity are often known, the way in which these attributes interact to produce the amenity is often unknown. Given the difficulty in converting multiple attributes into a unidimensional physical measure of an environmental amenity (e.g., habitat quality), analyses in the academic literature tend to use a single biophysical attribute as a proxy for the environmental amenity (e.g., species richness). A narrow focus on a single attribute, however, fails to consider the full range of biophysical attributes that are critical to the supply of an environmental amenity. Drawing on the production efficiency literature, we introduce an alternative conservation targeting approach that relies on distance functions to cost-efficiently allocate conservation funds across a spatially heterogeneous landscape. An approach based on distance functions has the advantage of not requiring a parametric specification of the amenity function (or cost function), but rather only requiring that the decision-maker identify important biophysical and economic attributes. We apply the distance-function approach empirically to an increasingly common, but little studied, conservation initiative: conservation contracting for water quality objectives. The contract portfolios derived from the distance-function application have many desirable properties, including intuitive appeal, robust performance across plausible parametric amenity measures, and the generation of ranking measures that can be easily used by field practitioners in complex decision-making environments that cannot be completely modeled. Working Paper # 2002-01

    Mass reservoirs surrounding massive infrared dark clouds: A view by near-infrared dust extinction

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    Context: Infrared Dark Clouds (IRDCs) harbor progenitors of high-mass stars. Little is known of the parental molecular clouds of the IRDCs. Aims: We demonstrate the feasibility of the near-infrared (NIR) dust extinction mapping in tracing the parental molecular clouds of IRDCs at the distances of D = 2.5 - 8 kpc. Methods: We derive NIR extinction maps for 10 prominent IRDC complexes using a color-excess mapping technique and NIR data from the UKIDSS/Galactic Plane Survey. We compare the resulting maps to the 13CO emission line data, to the 8 \mu m dust opacity data, and to the millimeter dust emission data. We derive distances for the clouds by comparing the observed NIR source densities to the Besancon stellar distribution model and compare them to the kinematic distance estimates. Results: The NIR extinction maps provide a view to the IRDC complexes over the dynamical range of Av = 2 - 40 mag, in spatial resolution of 30". The NIR extinction data correlate well with the 13CO data and probe a similar gas component, but also extend to higher column densities. The NIR data reveal a wealth of extended structures surrounding the dense gas traced by the 8 \mu m shadowing features and sub-mm dust emission, showing that the clouds contain typically > 10 times more mass than traced by those tracers. The IRDC complexes of our sample contain relatively high amount of high-column density material, and their cumulative column density distributions resemble active nearby star-forming clouds like Orion rather than less active clouds like California. Conclusions: NIR dust extinction data provide a new powerful tool to probe the mass distribution of the parental molecular clouds of IRDCs up to the distances of D = 8 kpc. This encourages for deeper NIR observations of IRDCs, because the sensitivity and resolution of the data can be directly enhanced with dedicated observations.Comment: 22 pages, 24 figures, accepted to A&A. A version with full resolution figures can be downloaded from http://www.mpia-hd.mpg.de/homes/jtkainul/NexusI/NexusI_v1.pd

    Development of concepts of capital and income in financial reporting in the nineteenth century

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    The study is concerned with the conception of capital and income in the changing economic circumstances of the late nineteenth century. This issue arises as a matter of interest from the confusing accounting for capital assets then followed, and which has become the subject of a small but significant literature. Methodologically the issue, and the literature it has provoked, provide a 'set' in which an accounting calculation is identified, its context considered and consequences evaluated. It introduces the idea that accounting had macroeconomic implications, and meets Hopwood's (1983) injunction that accounting ought to be considered in the context in which it arises. The study illustrates the significance of a flawed accounting founded on an inadequate definition of capital to adversely affect economic life by reference to the legal debate and litigation in English courts about the definition of profit available for distribution as dividends that occurred at the end of the nineteenth century. The study explores nineteenth century understanding of the concept of capital in economic philosophy on the basis that it would be in that body of philosophic literature that such ideas would have to be examined. The study finds that, for most of the nineteenth century, understanding of the nature of capital and income derived from the works of William Petty and Adam Smith. It held that capital and income were separate states of wealth. This conception of capital continued in the work of David Ricardo, Marx and J. S. Mill, and is evident also in the work of Alfred Marshall. The modern, twentieth century, understanding of capital and income as antithetical states of wealth is identified in the study as deriving from the work of the American economist Irving Fisher in 1896. The contribution of this thesis is to • Establish that the crisis in late nineteenth century financial reporting derived from the prevailing conception of capital and its relationship to income, • note that the conception in legislative requirements determining profit were consistent with that definition, and • identify the origin of the modern, twentieth century understanding of capital and income as antithetical states of wealth. The study provides an in-principle view that nineteenth century capital accounting had the capacity to cause misallocation of resources within an economy

    POISSON project - II - A multi-wavelength spectroscopic and photometric survey of young protostars in L 1641

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    Characterising stellar and circumstellar properties of embedded young stellar objects (YSOs) is mandatory for understanding the early stages of the stellar evolution. This task requires the combination of both spectroscopy and photometry, covering the widest possible wavelength range, to disentangle the various protostellar components and activities. As part of the POISSON project, we present a multi-wavelength spectroscopic and photometric investigation of embedded YSOs in L1641, aimed to derive the stellar parameters and evolutionary stages and to infer their accretion properties. Our database includes low-resolution optical-IR spectra from the NTT and Spitzer (0.6-40 um) and photometric data covering a spectral range from 0.4 to 1100 um, which allow us to construct the YSOs spectral energy distributions (SEDs) and to infer the main stellar parameters. The SED analysis allows us to group our 27 YSOs into nine Class I, eleven Flat, and seven Class II objects. However, on the basis of the derived stellar properties, only six Class I YSOs have an age of ~10^5 yr, while the others are older 5x10^5-10^6 yr), and, among the Flat sources, three out of eleven are more evolved objects (5x10^6-10^7 yr), indicating that geometrical effects can significantly modify the SED shapes. Inferred mass accretion rates (Macc) show a wide range of values (3.6x10^-9 to 1.2x10^-5 M_sun yr^-1), which reflects the age spread observed in our sample. Average values of mass accretion rates, extinction, and spectral indices decrease with the YSO class. The youngest YSOs have the highest Macc, whereas the oldest YSOs do not show any detectable jet activity in either images and spectra. We also observe a clear correlation among the YSO Macc, M*, and age, consistent with mass accretion evolution in viscous disc models.Comment: 61 pages, 16 figures; A&A in pres

    Older People, Sense of Coherence and Community

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    Population ageing is a global trend and even though years added to life often are lived in good health; it will have an impact on healthcare, housing and facilities, and social security costs. Healthy ageing in place, especially in one’s own home and community, increasingly receives attention from health professionals, researchers, and policymakers. In this chapter, we first discuss the meaning of the concept of healthy ageing, and how Sense of Coherence contributes to this process. Next, we discuss the characteristics of the community in which older people live their lives and how the community can provide resources (GRR and SRR) to strengthen Sense of Coherence and hence perceived well-being and quality of life

    Phocine distemper Virus: Current knowledge and future directions

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    Phocine distemper virus (PDV) was first recognized in 1988 following a massive epidemic in harbor and grey seals in north-western Europe. Since then, the epidemiology of infection in North Atlantic and Arctic pinnipeds has been investigated. In the western North Atlantic endemic infection in harp and grey seals predates the European epidemic, with relatively small, localized mortality events occurring primarily in harbor seals. By contrast, PDV seems not to have become established in European harbor seals following the 1988 epidemic and a second event of similar magnitude and extent occurred in 2002. PDV is a distinct species within the Morbillivirus genus with minor sequence variation between outbreaks over time. There is now mounting evidence of PDV-like viruses in the North Pacific/Western Arctic with serological and molecular evidence of infection in pinnipeds and sea otters. However, despite the absence of associated mortality in the region, there is concern that the virus may infect the large Pacific harbor seal and northern elephant seal populations or the endangered Hawaiian monk seals. Here, we review the current state of knowledge on PDV with particular focus on developments in diagnostics, pathogenesis, immune response, vaccine development, phylogenetics and modeling over the past 20 years

    Audiogram of a Cook Inlet beluga whale (Delphinapterus leucas)

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    Author Posting. © Acoustical Society of America, 2020. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 148(5), (2020): 3141, doi:10.1121/10.0002351.Noise is a stressor to wildlife, yet the precise sound sensitivity of individuals and populations is often unknown or unmeasured. Cook Inlet, Alaska belugas (CIBs) are a critically endangered and declining marine mammal population. Anthropogenic noise is a primary threat to these animals. Auditory evoked potentials were used to measure the hearing of a wild, stranded CIB as part of its rehabilitation assessment. The beluga showed broadband (4–128 kHz) and sensitive hearing (<80 dB) for a wide-range of frequencies (16–80 kHz), reflective of a healthy odontocete auditory system. Data were similar to healthy, adult belugas from the comparative Bristol Bay population (the only other published data set of healthy, wild marine mammal hearing). Repeated October and December 2017 measurements were similar, showing continued auditory health of the animal throughout the rehabilitation period. Hearing data were compared to pile-driving and container-ship noise measurements made in Cook Inlet, two sources of concern, suggesting masking is likely at ecologically relevant distances. These data provide the first empirical hearing data for a CIB allowing for estimations of sound-sensitivity in this population. The beluga's sensitive hearing and likelihood of masking show noise is a clear concern for this population struggling to recover.The work was conducted under Permit No. MMHSRP MMPA/ESA #18786-02 to T.R. and approved via the Institute for Animal Care and Use Protocol from the Woods Hole Oceanographic Institution. This publication was partially funded by the Joint Institute for the Study of the Atmosphere and Ocean (JISAO) under NOAA Cooperative Agreement No. NA15OAR4320063.2021-05-2

    Features of home and neighbourhood and the liveability of older South Africans

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    While older people live in developing countries, little is known about the relative importance of features of their communities in influencing their liveability. We examinecomponents of home and neighbourhood among older South Africans. Linear regression analyses revealed that features of home (basic amenities, household composition, financial status and safety) and neighbourhood (ability to shop for groceries, participate in organizations and feel safe from crime) are significantly associated with life satisfaction. Approaches to liveability that are person-centred and also set within contexts beyond home and neighbourhood are needed to addressboundaries between home and neighbourhood; incorporate personal resources into liveability models and import broader environmental contexts such as health and social policy
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