521 research outputs found
A Search for Hierarchical Triples using Kepler Eclipse Timing
We present the first results of a Kepler survey of 41 eclipsing binaries that
we undertook to search for third star companions. Such tertiaries will
periodically alter the eclipse timings through light travel time and dynamical
effects. We discuss the prevalence of starspots and pulsation among these
binaries and how these phenomena influence the eclipse times. There is no
evidence of short period companions (P < 700 d) among this sample, but we do
find evidence for long term timing variations in 14 targets (34%). We argue
that this finding is consistent with the presence of tertiary companions among
a significant fraction of the targets, especially if many have orbits measured
in decades. This result supports the idea that the formation of close binaries
involves the deposition of angular momentum into the orbital motion of a third
star.Comment: AJ, in press, 104 pages, 2 figure sets plus 1 regular figur
A hierarchical search for gravitational waves from supermassive black hole binary mergers
We present a method to search for gravitational waves from coalescing
supermassive binary black holes in LISA data. The search utilizes the
-statistic to maximize over, and determine the values of, the
extrinsic parameters of the binary system. The intrinsic parameters are
searched over hierarchically using stochastically generated multi-dimensional
template banks to recover the masses and sky locations of the binary. We
present the results of this method applied to the mock LISA data Challenge 1B
data set.Comment: 11 pages, 2 figures, for GWDAW-12 proceedings edition of CQ
The Pioneer Anomaly
Radio-metric Doppler tracking data received from the Pioneer 10 and 11
spacecraft from heliocentric distances of 20-70 AU has consistently indicated
the presence of a small, anomalous, blue-shifted frequency drift uniformly
changing with a rate of ~6 x 10^{-9} Hz/s. Ultimately, the drift was
interpreted as a constant sunward deceleration of each particular spacecraft at
the level of a_P = (8.74 +/- 1.33) x 10^{-10} m/s^2. This apparent violation of
the Newton's gravitational inverse-square law has become known as the Pioneer
anomaly; the nature of this anomaly remains unexplained. In this review, we
summarize the current knowledge of the physical properties of the anomaly and
the conditions that led to its detection and characterization. We review
various mechanisms proposed to explain the anomaly and discuss the current
state of efforts to determine its nature. A comprehensive new investigation of
the anomalous behavior of the two Pioneers has begun recently. The new efforts
rely on the much-extended set of radio-metric Doppler data for both spacecraft
in conjunction with the newly available complete record of their telemetry
files and a large archive of original project documentation. As the new study
is yet to report its findings, this review provides the necessary background
for the new results to appear in the near future. In particular, we provide a
significant amount of information on the design, operations and behavior of the
two Pioneers during their entire missions, including descriptions of various
data formats and techniques used for their navigation and radio-science data
analysis. As most of this information was recovered relatively recently, it was
not used in the previous studies of the Pioneer anomaly, but it is critical for
the new investigation.Comment: 165 pages, 40 figures, 16 tables; accepted for publication in Living
Reviews in Relativit
Planet Occurrence within 0.25 AU of Solar-type Stars from Kepler
We report the distribution of planets as a function of planet radius (R_p),
orbital period (P), and stellar effective temperature (Teff) for P < 50 day
orbits around GK stars. These results are based on the 1,235 planets (formally
"planet candidates") from the Kepler mission that include a nearly complete set
of detected planets as small as 2 Earth radii (Re). For each of the 156,000
target stars we assess the detectability of planets as a function of R_p and P.
We also correct for the geometric probability of transit, R*/a. We consider
first stars within the "solar subset" having Teff = 4100-6100 K, logg =
4.0-4.9, and Kepler magnitude Kp < 15 mag. We include only those stars having
noise low enough to permit detection of planets down to 2 Re. We count planets
in small domains of R_p and P and divide by the included target stars to
calculate planet occurrence in each domain. Occurrence of planets varies by
more than three orders of magnitude and increases substantially down to the
smallest radius (2 Re) and out to the longest orbital period (50 days, ~0.25
AU) in our study. For P < 50 days, the radius distribution is given by a power
law, df/dlogR= k R^\alpha. This rapid increase in planet occurrence with
decreasing planet size agrees with core-accretion, but disagrees with
population synthesis models. We fit occurrence as a function of P to a power
law model with an exponential cutoff below a critical period P_0. For smaller
planets, P_0 has larger values, suggesting that the "parking distance" for
migrating planets moves outward with decreasing planet size. We also measured
planet occurrence over Teff = 3600-7100 K, spanning M0 to F2 dwarfs. The
occurrence of 2-4 Re planets in the Kepler field increases with decreasing
Teff, making these small planets seven times more abundant around cool stars
than the hottest stars in our sample. [abridged]Comment: Submitted to ApJ, 22 pages, 10 figure
Gender-based violence against women in contemporary France: domestic violence and forced marriage policy since the Istanbul Convention
ABSTRACT:
In 2014, France ratified the Council of Europe’s Convention on Preventing and Combating Violence against Women and Domestic Violence (the Istanbul Convention) and passed the Law for Equality between Women and Men to bring French law into line with it. The Law for Equality between Women and Men situates the fight against violence against women within a broader context of the need to address inequalities between women and men. This is not new at the international level, but it is new to France. When the structural, transformative understandings of violence against women found in international texts are translated into national laws, policy documents and implementation on the ground, they might challenge widespread ideas about gender relations, or they might be diluted in order to achieve consensus. To what extent has French violence against women policy moved into line with UN and Council of Europe initiatives which present violence against women as both a cause and a consequence of gendered power relations? Have internationally accepted concepts of gender and gender-based violence been incorporated into French policy debates and, if so, how? What implications, if any, does all this have for the continued struggle in France and elsewhere to eliminate violence a gainst women?
RÉSUMÉ:
En 2014, la France a ratifié la Convention du Conseil de l’Europe sur la prévention et la lutte contre la violence à l’égard des femmes et la violence domestique (dite Convention d’Istanbul) et a adopté dans la foulée la loi pour l’égalité réelle entre les femmes et les hommes afin de mettre en conformité la législation française. Cette loi place la lutte contre la violence à l’égard des femmes dans un contexte de lutte contre les inégalités de genre. Si cela est loin d’être une nouveauté à l’échelle internationale, cela l’est en France. Lorsque les conceptions structurelles et transformatrices de la violence à l’égard des femmes présentes dans les textes internationaux sont traduites à l’échelle nationale en lois, documents d’orientation et mesures de mise en œuvre sur le terrain, elles peuvent alors remettre en question des idées largement répandues sur les rapports de genre, ou au contraire être édulcorées afin d’aboutir à un consensus. Dans quelle mesure la politique de la France relative à la violence à l’égard des femmes s’est-elle alignée sur les initiatives de l’ONU et du Conseil de l’Europe qui présentent ce type de violence comme étant à la fois une cause et une conséquence des rapports de force liés au genre? Le genre et la violence fondée sur le genre, qui sont des concepts internationalement reconnus, ont-ils été intégrés dans les débats politiques français, et si oui, de quelle manière? Quelles en sont les implications le cas échéant sur la poursuite, en France et ailleurs, de la lutte pour éliminer la violence à l’égard des femmes
Orientalising deafness: race and disability in imperial Britain
This article explores the conflations and connections that postcolonial and disability scholars have drawn between ‘race’, ‘colonialism’ and ‘disability’ from a historical perspective. By looking at the connections drawn between ‘race’ and ‘disability’ in the context of nineteenth-century imperial Britain, I hope to probe beyond them to examine the origins and implications of their interplay. I do so by focusing on ideas about deafness, an impairment radically reconfigured in the colonial period, and inflected with concerns about degeneration, belonging, heredity and difference. Disability, I argue, not only operated as an additional ‘category of difference’ alongside ‘race’ as a way of categorising and subjugating the various ‘others’ of Empire, but intersected with it. The ‘colonisation’ of disabled people in Britain and the ‘racial other’ by the British were not simply simultaneous processes or even analogous ones, but were part and parcel of the same cultural and discursive system. The colonising context of the nineteenth century, a period when British political, economic and cultural expansion over areas of South Asia, Australasia and Africa increased markedly, structured the way in which all forms of difference were recognised and expressed, including the difference of deafness. So too did the shifts in the raced and gendered thinking that accompanied it, as new forms of knowledge were developed to justify, explain and contest Britain's global position and new languages were developed through which to articulate otherness. Such developments reconfigured the meaning of disability. Disability was, in effect, ‘orientalised’. ‘Race’ I argue was formative in shaping what we have come to understand as ‘disability’ and vice versa; they were related fantasies of difference
Rasiowa–Sikorski deduction systems in computer science applications
AbstractA Rasiowa-Sikorski system is a sequence-type formalization of logics. The system uses invertible decomposition rules which decompose a formula into sequences of simpler formulae whose validity is equivalent to validity of the original formula. There may also be expansion rules which close indecomposable sequences under certain properties of relations appearing in the formulae, like symmetry or transitivity. Proofs are finite decomposition trees with leaves having “fundamental”, valid labels. The author describes a general method of applying the R-S formalism to develop complete deduction systems for various brands of C.S and A.I. logic, including a logic for reasoning about relative similarity, a three-valued software specification logic with McCarthy's connectives and Kleene quantifiers, a logic for nondeterministic specifications, many-sorted FOL with possibly empty carriers of some sorts, and a three-valued logic for reasoning about concurrency
Community mobilisation with women's groups facilitated by Accredited Social Health Activists (ASHAs) to improve maternal and newborn health in underserved areas of Jharkhand and Orissa: study protocol for a cluster-randomised controlled trial
Background: Around a quarter of the world's neonatal and maternal deaths occur in India. Morbidity and mortality are highest in rural areas and among the poorest wealth quintiles. Few interventions to improve maternal and newborn health outcomes with government-mandated community health workers have been rigorously evaluated at scale in this setting.The study aims to assess the impact of a community mobilisation intervention with women's groups facilitated by ASHAs to improve maternal and newborn health outcomes among rural tribal communities of Jharkhand and Orissa.Methods/design: The study is a cluster-randomised controlled trial and will be implemented in five districts, three in Jharkhand and two in Orissa. The unit of randomisation is a rural cluster of approximately 5000 population. We identified villages within rural, tribal areas of five districts, approached them for participation in the study and enrolled them into 30 clusters, with approximately 10 ASHAs per cluster. Within each district, 6 clusters were randomly allocated to receive the community intervention or to the control group, resulting in 15 intervention and 15 control clusters. Randomisation was carried out in the presence of local stakeholders who selected the cluster numbers and allocated them to intervention or control using a pre-generated random number sequence. The intervention is a participatory learning and action cycle where ASHAs support community women's groups through a four-phase process in which they identify and prioritise local maternal and newborn health problems, implement strategies to address these and evaluate the result. The cycle is designed to fit with the ASHAs' mandate to mobilise communities for health and to complement their other tasks, including increasing institutional delivery rates and providing home visits to mothers and newborns. The trial's primary endpoint is neonatal mortality during 24 months of intervention. Additional endpoints include home care practices and health care-seeking in the antenatal, delivery and postnatal period. The impact of the intervention will be measured through a prospective surveillance system implemented by the project team, through which mothers will be interviewed around six weeks after delivery. Cost data and qualitative data are collected for cost-effectiveness and process evaluations
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