5,360 research outputs found

    Analytical high-order post-Newtonian expansions for spinning extreme mass ratio binaries

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    We present an analytic computation of Detweiler's redshift invariant for a point mass in a circular orbit around a Kerr black hole, giving results up to 8.5 post-Newtonian order while making no assumptions on the magnitude of the spin of the black hole. Our calculation is based on the functional series method of Mano, Suzuki and Takasugi, and employs a rigorous mode-sum regularization prescription based on the Detweiler-Whiting singular-regular decomposition. The approximations used in our approach are minimal; we use the standard self-force expansion to linear order in the mass ratio, and the standard post-Newtonian expansion in the separation of the binary. A key advantage of this approach is that it produces expressions that include contributions at all orders in the spin of the Kerr black hole. While this work applies the method to the specific case of Detweiler's redshift invariant, it can be readily extended to other gauge invariant quantities and to higher post-Newtonian orders.Comment: Minor typos corrected, references adde

    Is There a Significant Difference Between the Results of the Coulomb Dissociation of 8B and the Direct Capture 7Be(p,g)8B Reaction?

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    Recent claims of the Seattle group of evidence of "slope difference between CD [Coulomb Dissociation] and direct [capture] results" are based on wrong and selective data. When the RIKEN2 data are included correctly, and previously published Direct Capture (DC) data are also included, we observe only a 1.9 sigma difference in the extracted so called "scale independent slope (b)", considerably smaller than claimed by the Seattle group. The very parameterization used by the Seattle group to extract the so called b-slope parameter has no physical foundation. Considering the physical slope (S' = dS/dE), we observe a 1.0 sigma agreement between slopes (S') measured in CD and DC, refuting the need for new theoretical investigation. The claim that S17(0) values extracted from CD data are approximately 10% lower than DC results, is based on misunderstanding of the CD method. Considering all of the published CD S17(0) results, with adding back an unconfirmed E2 correction of the MSU data, yields very consistent S17(0) results that agree with recent DC measurements of the Seattle and Weizmann groups. The recent correction of the b-slope parameter (0.25 1/MeV) suggested by Esbensen, Bertsch and Snover was applied to the wrong b-slope parameter calculated by the Seattle group. When considering the correct slope of the RIKEN2 data, this correction in fact leads to a very small b-slope parameter (0.14 1/MeV), less than half the central value observed for DC data, refuting the need to correct the RIKEN2 data. In particular it confirms that the E2 contribution in the RIKEN2 data is negligible. The dispersion of measured S17(0) is mostly due to disagreement among individual DC experiments and not due to either experimental or theoretical aspects of CD.Comment: Reference 12 amended with an important communication from Dr. Bertsc

    Fully automated segmentation and tracking of the intima media thickness in ultrasound video sequences of the common carotid artery

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    Abstract—The robust identification and measurement of the intima media thickness (IMT) has a high clinical relevance because it represents one of the most precise predictors used in the assessment of potential future cardiovascular events. To facilitate the analysis of arterial wall thickening in serial clinical investigations, in this paper we have developed a novel fully automatic algorithm for the segmentation, measurement, and tracking of the intima media complex (IMC) in B-mode ultrasound video sequences. The proposed algorithm entails a two-stage image analysis process that initially addresses the segmentation of the IMC in the first frame of the ultrasound video sequence using a model-based approach; in the second step, a novel customized tracking procedure is applied to robustly detect the IMC in the subsequent frames. For the video tracking procedure, we introduce a spatially coherent algorithm called adaptive normalized correlation that prevents the tracking process from converging to wrong arterial interfaces. This represents the main contribution of this paper and was developed to deal with inconsistencies in the appearance of the IMC over the cardiac cycle. The quantitative evaluation has been carried out on 40 ultrasound video sequences of the common carotid artery (CCA) by comparing the results returned by the developed algorithm with respect to ground truth data that has been manually annotated by clinical experts. The measured IMTmean ± standard deviation recorded by the proposed algorithm is 0.60 mm ± 0.10, with a mean coefficient of variation (CV) of 2.05%, whereas the corresponding result obtained for the manually annotated ground truth data is 0.60 mm ± 0.11 with a mean CV equal to 5.60%. The numerical results reported in this paper indicate that the proposed algorithm is able to correctly segment and track the IMC in ultrasound CCA video sequences, and we were encouraged by the stability of our technique when applied to data captured under different imaging conditions. Future clinical studies will focus on the evaluation of patients that are affected by advanced cardiovascular conditions such as focal thickening and arterial plaques

    Angular distributions of γ rays from the 7Li(p,γ) reaction at low energies

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    Angular distributions of the 14–17 MeV γ rays from the 7Li(p,γ) reaction at Ep=450, 402, and 80 keV were measured at 0°≤θlab≤135°, using a BGO detector and a 28-μg/cm2 LiF target. The angular distributions at Ep=450 and 402 keV agree with the previous results by Mainsbridge; at Ep=80 keV the ground-state transition is anisotropic on the order of 20%, confirming recent results by Chasteler et al

    Boron Plus Deuteron Reactions

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    Gamma and alpha emission from the 15-Mev level of C12 is investigated in the reaction B11(d, n)C12*. An upper limit on the ratio of α- to γ-radiation from the state is Γα / Γγ6 Mev and Eγ=3.2 Mev following B12 decay. The cross section for the production of B12 is given as a function of bombarding energy for 0.5<~Ed<~3.25 Mev

    The Irish grey partridge conservation strategy: an update 1995-1998.

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    KAVANAGH, B.P., O\u27GORMAN,C.,AND BUCKLEY, C.: THE IRISH GREY PARTRIDGE (PERDIX PERDIX) CONSERVATION STRATEGY: AN UPDATE 1995-1998.In May 1996 a strategy for the conservation of the last remaining population of the Irish Grey partridge was initiated. The strategy is a multipronged approach based on a) predation reduction, b) habitat improvement and c) monitoring of the birds’ response. A full-time game keeper was employed to reduce red fox (Vulpes vulpes), mink (Mustella vison), stoat (Mustella erminea), rat (Rattus norvegicus), grey crow (Corvus corone cornix)and magpie (Pica pica) numbers in a defined study area of 1,000 hectares of cutaway bog at Boora in County Offaly. The habitatis a mozaic of cutaway bogland, conferous forestry, newly created farmland and wetland. The area contianed 6-8 pairs of breeding grey partridge in spring 1996. Bare peat areas within the study area were selected and a mix of either grasser or grains were planted in 0,2 hectare blocks to provide nesting or chick rearing cover for birds. These plots were neither sprayed or harvested and have been left to develop naturally after planting. Fifteen hectares were planted over two years, 1996-97. In spring 1997 a number of male partridges were trapped and fitted with radio collars. Their home range and habitat preferences were recorded continuously for up to ten months. Radio-tracked birds were recorded leaving the keepered area and moving to winter stubble fields on adjoining farmland. Two successful coveys were produced in 1996 which resulted in a autumn count of 27 partridges in the study area. In spring 1997 the population in the study area was again 6-8 pairs. Two successful coveys were again produced in 1997 giving an autumn population was 23 birds within the study area. Winter survival in 1997/98 was poor. In spring 1998 only 4-6 pairs of partridges were found in the study area. Partridge numbers continue to decline both within and outside the study area. The remaining population is now less than 20 breeding pairs in total

    National counter-terrorism (C-T) policies and challenges to human rights and civil liberties: Case study of United Kingdom

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    In the UK the rise post-2005 in “home-grown” terrorism, relying to a significant extent on strikes on soft targets by “self-starters,” means that the search for effective preventive measures remains a continuing concern. Below a number of the preventive counter-terror measures adopted post-9/11, and incrementally strengthened in response to the current threat, are found to fall into three categories and represent interventions at the stages in the path toward attacks. This chapter focuses on selected examples of these preventive measures. In terms of three key stages, firstly, there is the attempt to prevent radicalization, under the “Prevent” strategy. A second strategy relies on taking certain measures to control the activities of those considered likely – on the balance of probabilities – to engage in terrorist-related activity. A third preventive strategy relies on the special terrorism offences under the Terrorism Acts 2000 and 2006, as amended, intended to allow for intervention at a very early stage in terrorist plots and in preparing or instigating terrorist acts (“precursor” offences)

    Unsung heroes: Constituency election agents in British general elections

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    Despite their central role in the electoral process, constituency agents have been largely overlooked by political scientists and this article seeks to rectify the omission. It sketches the origins and development of the role of agent from the late 19th century and suggests that a serious rethink of the role took place in the 1990s. Survey-based evidence about the social characteristics of agents is presented confirming that they are largely middle-aged, middle-class, well-educated men. They are also becoming more experienced, offer realistic assessments of the impact of constituency campaigning and, arguably, many take a long-term view of how their party's support can be maximised
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