944 research outputs found

    Constraints on the environment and energetics of the Broad-Line Ic SN2014ad from deep radio and X-ray observations

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    Broad-line type Ic Supernovae (BL-Ic SNe) are characterized by high ejecta velocity (104\gtrsim 10^4 km s1^{-1}) and are sometimes associated with the relativistic jets typical of long duration (2\gtrsim 2 s) Gamma-Ray Bursts (L-GRBs). The reason why a small fraction of BL-Ic SNe harbor relativistic jets is not known. Here we present deep X-ray and radio observations of the BL-Ic SN2014ad extending from 1313 to 930930 days post explosion. SN2014ad was not detected at either frequency and has no observational evidence of a GRB counterpart. The proximity of SN2014ad (d26d\sim 26 Mpc) enables very deep constraints on the progenitor mass-loss rate M˙\dot{M} and on the total energy of the fast ejecta EE. We consider two synchrotron emission scenarios for a wind-like circumstellar medium (CSM): (i) uncollimated non-relativistic ejecta, and (ii) off-axis relativistic jet. Within the first scenario our observations are consistent with GRB-less BL-Ic SNe characterized by a modest energy budget of their fast ejecta (E1045E \lesssim 10^{45} erg), like SNe 2002ap and 2010ay. For jetted explosions, we cannot rule out a GRB with E1051E \lesssim 10^{51} erg (beam-corrected) with a narrow opening angle (θj5\theta_j \sim 5^{\circ}) observed moderately off-axis (θobs30\theta_{\rm obs} \gtrsim 30^{\circ}) and expanding in a very low CSM density (M˙\dot{M} 106\lesssim 10^{-6} M_{\odot} yr1^{-1}). Our study shows that off-axis low-energy jets expanding in a low-density medium cannot be ruled out even in the most nearby BL-Ic SNe with extensive deep observations, and might be a common feature of BL-Ic SNe.Comment: 9 pages, 5 figures, accepted in Ap

    The NIF LinkOut Broker: A Web Resource to Facilitate Federated Data Integration using NCBI Identifiers

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    This paper describes the NIF LinkOut Broker (NLB) that has been built as part of the Neuroscience Information Framework (NIF) project. The NLB is designed to coordinate the assembly of links to neuroscience information items (e.g., experimental data, knowledge bases, and software tools) that are (1) accessible via the Web, and (2) related to entries in the National Center for Biotechnology Information’s (NCBI’s) Entrez system. The NLB collects these links from each resource and passes them to the NCBI which incorporates them into its Entrez LinkOut service. In this way, an Entrez user looking at a specific Entrez entry can LinkOut directly to related neuroscience information. The information stored in the NLB can also be utilized in other ways. A second approach, which is operational on a pilot basis, is for the NLB Web server to create dynamically its own Web page of LinkOut links for each NCBI identifier in the NLB database. This approach can allow other resources (in addition to the NCBI Entrez) to LinkOut to related neuroscience information. The paper describes the current NLB system and discusses certain design issues that arose during its implementation

    Twisted Quantum Fields on Moyal and Wick-Voros Planes are Inequivalent

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    The Moyal and Wick-Voros planes A^{M,V}_{\theta} are *-isomorphic. On each of these planes the Poincar\'e group acts as a Hopf algebra symmetry if its coproducts are deformed by twist factors. We show that the *-isomorphism T: A^M_{\theta} to A^V_{\theta} does not also map the corresponding twists of the Poincar\'e group algebra. The quantum field theories on these planes with twisted Poincar\'e-Hopf symmetries are thus inequivalent. We explicitly verify this result by showing that a non-trivial dependence on the non-commutative parameter is present for the Wick-Voros plane in a self-energy diagram whereas it is known to be absent on the Moyal plane (in the absence of gauge fields). Our results differ from these of (arXiv:0810.2095 [hep-th]) because of differences in the treatments of quantum field theories.Comment: 12 page

    Inequivalence of QFT's on Noncommutative Spacetimes: Moyal versus Wick-Voros

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    In this paper, we further develop the analysis started in an earlier paper on the inequivalence of certain quantum field theories on noncommutative spacetimes constructed using twisted fields. The issue is of physical importance. Thus it is well known that the commutation relations among spacetime coordinates, which define a noncommutative spacetime, do not constrain the deformation induced on the algebra of functions uniquely. Such deformations are all mathematically equivalent in a very precise sense. Here we show how this freedom at the level of deformations of the algebra of functions can fail on the quantum field theory side. In particular, quantum field theory on the Wick-Voros and Moyal planes are shown to be inequivalent in a few different ways. Thus quantum field theory calculations on these planes will lead to different physics even though the classical theories are equivalent. This result is reminiscent of chiral anomaly in gauge theories and has obvious physical consequences. The construction of quantum field theories on the Wick-Voros plane has new features not encountered for quantum field theories on the Moyal plane. In fact it seems impossible to construct a quantum field theory on the Wick-Voros plane which satisfies all the properties needed of field theories on noncommutative spaces. The Moyal twist seems to have unique features which make it a preferred choice for the construction of a quantum field theory on a noncommutative spacetime.Comment: Revised version accepted for publication in Phys.Rev.D; 18 page

    The Effects of Perspective Taking Implementing Intentions on Employee Evaluations and Hostile Sexism

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    The current research examined whether gender bias in the workplace could be reduced through perspective taking implementation intentions, which are if–then statements that specify how to accomplish goals (Gollwitzer, 1999). Amazon MTurk participants (N = 180, 53% male) learned they would complete a two-step performance review for a consulting company. Prior to receiving a male or female employee’s record, all participants were given a goal strategy to be fair in their review, with half also receiving an if–then strategy that encouraged perspective taking. Participants rated the employee on three work related dimensions (skillset, performance, and traits), provided an overall promotion recommendation, and completed the Ambivalent Sexism Inventory (Glick & Fiske, 1996). Although we did not find evidence of gender bias on the work measures, we found that the implementation intention strategy resulted in more positive employee evaluations overall and less hostile sexism than a simple goal strategy. We discuss the potential organizational benefits of employing perspective taking implementation intentions

    An ontological approach to describing neurons and their relationships

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    The advancement of neuroscience, perhaps one of the most information rich disciplines of all the life sciences, requires basic frameworks for organizing the vast amounts of data generated by the research community to promote novel insights and integrated understanding. Since Cajal, the neuron remains a fundamental unit of the nervous system, yet even with the explosion of information technology, we still have few comprehensive or systematic strategies for aggregating cell-level knowledge. Progress toward this goal is hampered by the multiplicity of names for cells and by lack of a consensus on the criteria for defining neuron types. However, through umbrella projects like the Neuroscience Information Framework (NIF) and the International Neuroinformatics Coordinating Facility (INCF), we have the opportunity to propose and implement an informatics infrastructure for establishing common tools and approaches to describe neurons through a standard terminology for nerve cells and a database (a Neuron Registry) where these descriptions can be deposited and compared. This article provides an overview of the problem and outlines a solution approach utilizing ontological characterizations. Based on illustrative implementation examples, we also discuss the need for consensus criteria to be adopted by the research community, and considerations on future developments. A scalable repository of neuron types will provide researchers with a resource that materially contributes to the advancement of neuroscience

    Trehalose/sodium hyaluronate eye drops in post-cataract ocular surface disorders

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    Purpose Prospective, randomised, open-label, comparative study to evaluate efficacy of trehalose/sodium hyaluronate eye drops for post-operative discomfort and tear film stability in patients undergoing cataract surgery. Methods Patients with healthy ocular surface, subclinical, or mild dry eye were enrolled. Tear breakup time (TBUT), Schirmer test, dry eye symptoms, corneal fluorescein staining (CFS), and ocular surface disease (OSDI) evaluation were performed pre-operatively and at two and four weeks after surgery. Patients were assigned to receive trehalose/sodium hyaluronate eye drops b.i.d (Group A), or 0.9% unpreserved sodium chloride eye drops b.i.d for 4 weeks (Group B). Results One hundred and thirty-five patients were randomised, 66 patients in Group A (73.2 +/- 4.5 years) and 69 patients in Group B (74.3 +/- 3.8 years), 60.8% females. Fifteen patients (8 Group A) were lost at follow-up. Pre-operatively, no between-group differences were observed, and TBUT increased in Group A between the pre-operative and 2 and 4 week evaluations and was higher in group A than in Group B at 4 weeks. Schirmer test and CFS showed an improvement only in Group A four weeks post-operatively. In Group A an improvement was observed after two and four weeks in foreign body and puncture sensation, whilst a difference in blinking discomfort was observed after four weeks. In Group B we observed an improvement in puncture sensation two and four weeks after surgery. Mean OSDI scores differences between the two groups were significant at four weeks. Conclusions Trehalose/sodium hyaluronate eye drops were effective in reducing signs and symptoms of dry eye and improving tear film stabilit

    Covariant Quantum Fields on Noncommutative Spacetimes

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    A spinless covariant field ϕ\phi on Minkowski spacetime \M^{d+1} obeys the relation U(a,Λ)ϕ(x)U(a,Λ)1=ϕ(Λx+a)U(a,\Lambda)\phi(x)U(a,\Lambda)^{-1}=\phi(\Lambda x+a) where (a,Λ)(a,\Lambda) is an element of the Poincar\'e group \Pg and U:(a,Λ)U(a,Λ)U:(a,\Lambda)\to U(a,\Lambda) is its unitary representation on quantum vector states. It expresses the fact that Poincar\'e transformations are being unitary implemented. It has a classical analogy where field covariance shows that Poincar\'e transformations are canonically implemented. Covariance is self-reproducing: products of covariant fields are covariant. We recall these properties and use them to formulate the notion of covariant quantum fields on noncommutative spacetimes. In this way all our earlier results on dressing, statistics, etc. for Moyal spacetimes are derived transparently. For the Voros algebra, covariance and the *-operation are in conflict so that there are no covariant Voros fields compatible with *, a result we found earlier. The notion of Drinfel'd twist underlying much of the preceding discussion is extended to discrete abelian and nonabelian groups such as the mapping class groups of topological geons. For twists involving nonabelian groups the emergent spacetimes are nonassociative.Comment: 20 page

    Length functions on currents and applications to dynamics and counting

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    The aim of this (mostly expository) article is twofold. We first explore a variety of length functions on the space of currents, and we survey recent work regarding applications of length functions to counting problems. Secondly, we use length functions to provide a proof of a folklore theorem which states that pseudo-Anosov homeomorphisms of closed hyperbolic surfaces act on the space of projective geodesic currents with uniform north-south dynamics.Comment: 35pp, 2 figures, comments welcome! Second version: minor corrections. To appear as a chapter in the forthcoming book "In the tradition of Thurston" edited by V. Alberge, K. Ohshika and A. Papadopoulo
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