11,363 research outputs found

    On the fidelity of the core mass functions derived from dust column density data

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    Aims: We examine the recoverability and completeness limits of the dense core mass functions (CMFs) derived for a molecular cloud using extinction data and a core identification scheme based on two-dimensional thresholding. Methods: We performed simulations where a population of artificial cores was embedded into the variable background extinction field of the Pipe nebula. We extracted the cores from the simulated extinction maps, constructed the CMFs, and compared them to the input CMFs. The simulations were repeated using a variety of extraction parameters and several core populations with differing input mass functions and differing degrees of crowding. Results: The fidelity of the observed CMF depends on the parameters selected for the core extraction algorithm for our background. More importantly, it depends on how crowded the core population is. We find that the observed CMF recovers the true CMF reliably when the mean separation of cores is larger than their mean diameter (f>1). If this condition holds, the derived CMF is accurate and complete above M > 0.8-1.5 Msun, depending on the parameters used for the core extraction. In the simulations, the best fidelity was achieved with the detection threshold of 1 or 2 times the rms-noise of the extinction data, and with the contour level spacings of 3 times the rms-noise. Choosing larger threshold and wider level spacings increases the limiting mass. The simulations show that when f>1.5, the masses of individual cores are recovered with a typical uncertainty of 25-30 %. When f=1 the uncertainty is ~60 %. In very crowded cases where f<1 the core identification algorithm is unable to recover the masses of the cores adequately. For the cores of the Pipe nebula f~2.0 and therefore the use of the method in that region is justified.Comment: 9 pages, 6 figures, accepted for publication in A&

    The cuticle

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    The nematode cuticle is an extremely flexible and resilient exoskeleton that permits locomotion via attachment to muscle, confers environmental protection and allows growth by molting. It is synthesised five times, once in the embryo and subsequently at the end of each larval stage prior to molting. It is a highly structured extra-cellular matrix (ECM), composed predominantly of cross-linked collagens, additional insoluble proteins termed cuticlins, associated glycoproteins and lipids. The cuticle collagens are encoded by a large gene family that are subject to strict patterns of temporal regulation. Cuticle collagen biosynthesis involves numerous co- and post-translational modification, processing, secretion and cross-linking steps that in turn are catalysed by specific enzymes and chaperones. Mutations in individual collagen genes and their biosynthetic pathway components can result in a range of defects from abnormal morphology (dumpy and blister) to embryonic and larval death, confirming an essential role for this structure and highlighting its potential as an ECM experimental model system

    Responding to Gender-based Violence in Scotland: The Scope of the Gender Equality Duty to Drive Cultural and Practical Change

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    This piece of research has its roots in well-established policy debates in Scotland. Following the passage of the Criminal Justice (Scotland) Act 2003, which introduced a new statutory aggravation for crimes motivated by religious prejudice, the then Scottish Executive convened a working group to explore and make recommendations on whether there was a case for similar provision for other social groups. The report and recommendations of the Hate Crime Working Group, published in 2004, recognised that the debate to introduce gender aggravation was one of the most contested issues which it had looked at, but it did not believe that at that stage it could recommend introducing such a provision. These debates re-emerged with Patrick Harvie’s member’s bill which was to become the Offences (Aggravation by Prejudice) (Scotland) Act 2009. The Equality and Human Rights Commission, along with many organisations in the women’s sector in Scotland, stated in its evidence on the bill that it did not believe that a statutory gender aggravation would be an effective additional criminal justice response to identifying and tackling crime motivated by gender prejudice. This of course begs the question about what is required to better address these types of crime. This piece of research, undertaken for the EHRC by the Scottish Centre for Crime and Justice Research, aims to be a useful contribution to this debate. It explores some of the arguments for and against a gender aggravation in Scots criminal law before considering the evidence thus far of the impact the Gender Equality Duty (GED) has had on Scotland’s criminal justice system, and makes a number of useful recommendations for the future. The EHRC subscribes to a gendered model of violence against women, which sees it as both a cause and consequence of wider gender inequality. We hope this report can help inform ongoing policy debate on criminal justice agencies’ response to violence against women, particularly in light of the new single equality duty which Scottish Ministers will in due course place on Scottish public authorities under powers conferred on them by the Equality Act 2010. We believe that the appropriate regulatory framework for public bodies working in this area is one of the prerequisites for further improving on Scotland’s record of identifying and tackling gender-based crime

    Development of a simulation-based decision support tool for renewable energy integration and demand-supply matching

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    This paper describes a simulation-based decision support tool, MERIT, which has been developed to assist in the assessment of renewable energy systems by focusing on the degree of match achievable between energy demand and supply. Models are described for the prediction of the performance of PV, wind and battery technologies. These models are based on manufacturers' specifications, location-related parameters and hourly weather data. The means of appraising the quality of match is outlined and examples are given of the application of the tool at the individual building and community levels

    Development and demonstration of a renewable energy based demand/supply decision support tool for the building design profession

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    Future cities are likely to be characterised by a greater level of renewable energy systems deployment. Maximum impact will be achieved when such systems are used to offset local energy demands in contrast to current philosophy dictating the grid connection of large schemes. This paper reports on the development of a software tool, MERIT, for demand/ supply matching. The purpose of MERIT is to assist with the deployment of renewable energy systems at all scales. This paper describes the procedures used to match heterogeneous supply technologies to a set of demand profiles corresponding to the different possible fuel types

    On-line energy services for smart homes

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    The EC funded 'Smart Homes' project commenced in 2001 as a 3 year programme. The primary objective is to establish Internet-based energy services and test these within field trials in Sweden, Greece, the Czech Republic and the UK. The tasks include the prototyping and testing of energy services for citizens and professionals, and the establishment of cable and wireless approaches to Internet connection. The implementations are based on residential gateway, or 'e-box', technology. Users, for example utilities, citizens, local authority energy managers and health care providers, can access the information through standard Web browsers and, depending on the particular energy service, may transmit information or control requests back to the originating homes. This paper sets out the overall structure of the SmartHomes system and reports on progress to date

    Continuum Variability of Deeply Embedded Protostars as a Probe of Envelope Structure

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    Stars may be assembled in large growth spurts, however the evidence for this hypothesis is circumstantial. Directly studying the accretion at the earliest phases of stellar growth is challenging because young stars are deeply embedded in optically thick envelopes, which have spectral energy distributions that peak in the far-IR, where observations are difficult. In this paper, we consider the feasibility of detecting accretion outbursts from these younger stars by investigating the timescales for how the protostellar envelope responds to changes in the emission properties of the central source. The envelope heats up in response to an outburst, brightening at all wavelengths and with the emission peak moving to shorter wavelengths. The timescale for this change depends on the time for dust grains to heat and re-emit photons and the time required for the energy to escape the inner, optically-thick portion of the envelope. We find that the dust response time is much shorter than the photon propagation time and thus the timescale over which the emission varies is set by time delays imposed by geometry. These times are hours to days near the peak of the spectral energy distribution and weeks to months in the sub-mm. The ideal location to quickly detect continuum variability is therefore in the mid- to far-IR, near the peak of the spectral energy distribution, where the change in emission amplitude is largest. Searching for variability in sub-mm continuum emission is also feasible, though with a longer time separation and a weaker relationship between the amount of detected emission amplitude and change in central source luminosity. Such observations would constrain accretion histories of protostars and would help to trace the disk/envelope instabilities that lead to stellar growth.Comment: 25 pages, 6 figures, accepted for publication in the Astrophysical Journa

    Third Interger Resonance Slow Extraction Using RFKO at High Space Charge

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    A proposal to search for direct {\mu}-->e conversion at Fermilab requires slow, resonant extraction of an intense proton beam. Large space charge forces will present challenges, partly due to the substantial betatron tune spread. The main challenges will be maintaining a uniform spill profile and moderate losses at the septum. We propose to use "radio frequency knockout" (RFKO) for fine tuning the extraction. Strategies for the use of the RFKO method will be discussed here in the context of the Mu2e experiment. The feasibility of this method has been demonstrated in simulations.Comment: 3 pp. 2nd International Particle Accelerator Conference: IPAC 2011. 4-9 Sep 2011. San Sebastian, Spai
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