9,938 research outputs found

    The Cohen Macaulay property for noncommutative rings

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    Let R be a noetherian ring which is a finite module over its centre Z(R). This paper studies the consequences for R of the hypothesis that it is a maximal Cohen Macaulay Z(R)-module. Old results are reviewed and a number of new results are proved. The additional hypothesis of homological grade symmetry is proposed as the appropriate extra lever needed to extend the classical commutative homological hierarchy to this setting, and results are given offering evidence in support of this proposal.Comment: Preliminary version; comments welcom

    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

    Two \u3ci\u3eEntomophthora\u3c/i\u3e Species Associated with Disease Epizootics of the Alfalfa Weevil, \u3ci\u3eHypera Postica\u3c/i\u3e (Coleoptera: Curculionidae), in Ontario

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    Recent studies have shown that disease epizootics in Ontario populations of the alfalfa weevil, Hypera postica (Gyllenhal), are caused by a complex of two fungi

    Electro-optic bunch diagnostics on ALICE

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    An electro-optic longitudinal bunch profile monitor has been implemented on ALICE (Accelerators and Lasers in Combined Experiments) at the Daresbury Laboratories and will be used both to characterise the electron bunch and to provide a testbed for electro-optic techniques. The electro-optic station is located immediately after the bunch compressor, within the FEL cavity; its location allows nearby OTR, beam profile monitors and Coherent Synchrontron Radiation (CSR) diagnostics to be used for calibration and benchmarking. We discuss the implementation and the planned studies on electro-optic diagnostics using this diagnostic station

    Upconversion of a relativistic Coulomb field terahertz pulse to the near infrared

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    We demonstrate the spectral upconversion of a unipolar subpicosecond terahertz (THz) pulse, where the THz pulse is the Coulomb field of a single relativistic electron bunch. The upconversion to the optical allows remotely located detection of long wavelength and nonpropagating components of the THz spectrum, as required for ultrafast electron bunch diagnostics. The upconversion of quasimonochromatic THz radiation has also been demonstrated, allowing the observation of distinct sum- and difference-frequency mixing components in the spectrum. Polarization dependence of first and second order sidebands at ωopt±ωTHz, and ωopt±2ωTHz, respectively, confirms the χ(2) frequency mixing mechanism

    SDSSJ14584479+3720215: A Benchmark JHK Blazar Light Curve from the 2MASS Calibration Scans

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    Active galactic nuclei (AGNs) are well-known to exhibit flux variability across a wide range of wavelength regimes, but the precise origin of the variability at different wavelengths remains unclear. To investigate the relatively unexplored near-IR variability of the most luminous AGNs, we conduct a search for variability using well sampled JHKs-band light curves from the 2MASS survey calibration fields. Our sample includes 27 known quasars with an average of 924 epochs of observation over three years, as well as one spectroscopically confirmed blazar (SDSSJ14584479+3720215) with 1972 epochs of data. This is the best-sampled NIR photometric blazar light curve to date, and it exhibits correlated, stochastic variability that we characterize with continuous auto-regressive moving average (CARMA) models. None of the other 26 known quasars had detectable variability in the 2MASS bands above the photometric uncertainty. A blind search of the 2MASS calibration field light curves for AGN candidates based on fitting CARMA(1,0) models (damped-random walk) uncovered only 7 candidates. All 7 were young stellar objects within the {\rho} Ophiuchus star forming region, five with previous X-ray detections. A significant {\gamma}-ray detection (5{\sigma}) for the known blazar using 4.5 years of Fermi photon data is also found. We suggest that strong NIR variability of blazars, such as seen for SDSSJ14584479+3720215, can be used as an efficient method of identifying previously-unidentified {\gamma}-ray blazars, with low contamination from other AGN.Comment: 6 pages, 3 figures, ApJ Accepte

    Methanol Masers as Tracers of Circumstellar Disks

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    We show that in many methanol maser sources the masers are located in lines, with a velocity gradient along them which suggests that the masers are situated in edge-on circumstellar, or protoplanetary, disks. We present VLBI observations of the methanol maser source G309.92+0.48, in the 12.2 GHz transition, which confirm previous observations that the masers in this source lie along a line. We show that such sources are not only linear in space but, in many cases, also have a linear velocity gradient. We then model these and other data in both the 6.7 GHz and the 12.2 GHz transition from a number of star formation regions, and show that the observed spatial and velocity distribution of methanol masers, and the derived Keplerian masses, are consistent with a circumstellar disk rotating around an OB star. We consider this and other hypotheses, and conclude that about half of these methanol masers are probably located in edge-on circumstellar disks around young stars. This is of particular significance for studies of circumstellar disks because of the detailed velocity information available from the masers.Comment: 38 pages, 13 figures accepted by Ap
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