Black Hole Formation in Fallback Supernova and the Spins of LIGO Sources

Here we investigate within the context of field binary progenitors how the the spin of LIGO sources vary when the helium star-descendent black hole (BH) is formed in a failed supernova (SN) explosion rather than by direct collapse. To this end, we make use of 3d hydrodynamical simulations of fallback supernova in close binary systems with properties designed to emulate LIGO sources. By systematically varying the explosion energy and the binary properties, we are able to explore the effects that the companion has on redistributing the angular momentum of the system. We find that, unlike the mass, the spin of the newly formed BH varies only slightly with the currently theoretically unconstrained energy of the SN and is primarily determined by the initial binary separation. In contrast, variations in the initial binary separation yield sizable changes on the resultant effective spin of the system. This implies that the formation pathways of LIGO sources leading to a particular effective spin might be far less restrictive than the standard direct collapse scenario suggests.Comment: 7 pages, 5 figures, submitted to ApJ Letter

Sleptons without Hadrons

Multilepton searches for electroweakino and slepton pair production at hadron colliders remain some of the best means to test weak-scale supersymmetry. Searches at the CERN Large Hadron Collider, however, are limited by large diboson and top quark pair backgrounds, despite the application of traditional, central jet vetoes. In this context, we report the impact of introducing dynamic jet vetoes in searches for colorless superpartners. As a representative scenario, we consider the Drell-Yan production of a pair of right-handed smuons decaying into a dimuon system accompanied with missing transverse energy. As an exploratory step, we consider several global and local measures of the leptonic and hadronic activity to construct the veto. In most all cases, we find that employing a dynamic jet veto improves the sensitivity, independently of the integrated luminosity. The inclusion of non-perturbative multiple particle interactions and next-to-leading order jet merging does not alter this picture. Directions for further improvements are discussed.Comment: 18 pages; 7 figures; additional discussions added; journal version; results unchange

Did GW170817 harbor a pulsar?

If the progenitor of GW170817 harbored a pulsar, then a Poynting flux dominated bow-shock cavity would have been expected to form around the traveling binary. The characteristic size of this evacuated region depends strongly on the spin-down evolution of the pulsar companion, which in turn depends on the merging timescale of the system. If this evacuated region is able to grow to a sufficiently large scale, then the deceleration of the jet, and thus the onset of the afterglow, would be noticeably delayed. The first detection of afterglow emission, which was uncovered 9.2 days after the $\gamma$-ray burst trigger, can thus be used to constrain the size of a pre-existing pulsar-wind cavity. We use this information, together with a model of the jet to place limits on the presence of a pulsar in GW170817 and discuss the derived constraints in the context of the observed double neutron star binary population. We find that the majority of Galactic systems that are close enough to merge within a Hubble time would have carved a discernibly large pulsar-wind cavity, inconsistent with the onset timescale of the X-ray afterglow of GW170817. Conversely, the recently detected system J1913+1102, which host a low-luminosity pulsar, provides a congruous Milky Way analog of GW170817's progenitor model. This study highlights the potential of the proposed observational test for gaining insight into the origin of double neutron star binaries, in particular if the properties of Galactic systems are representative of the overall merging population.Comment: Accepted for publication in ApJL, 6 pages, 5 figure

La Confédération doit-elle imposer une séparation entre banque commerciale et banque d'investissement en se basant sur les impacts de cette décision et des comparaisons internationales ?

Le but de ce travail est de déterminer si la Confédération doit imposer une séparation entre banque commerciale et banque d’investissement, à l’UBS et au Crédit Suisse. La question est survenue durant la crise financière de 2007, après que les activités de banque d’investissement aient fait perdre des milliards, à l’instar d’UBS qui a subi des pertes de plus de 50 milliards de francs. Ces pertes sont dues à une prise de risque excessive sur le marché des produits structurés, avec l’achat, par exemple de CDO et la forte exposition des banques aux contreparties de marchés, ce qui a créé une très forte interconnexion entre les institutions financières. Cette forte exposition aux risques a été permise grâce à des couvertures de marché qui garantissaient des produits structurés et à un manque de contrôle de la part des états. De plus, en raison de rémunération variable, certains employés n’ont pas hésité à exposer leur banque à des risques importants afin d’augmenter leur performance, et ainsi, leur salaire. Afin de remédier à ces risques, la meilleure solution pour la Suisse est, selon moi, de séparer les activités de banque commerciale et banque d’investissement. Cette décision permettrait de diminuer le risque que subissent les épargnants des grandes banques suisses mais également celui des citoyens qui ne devraient plus, en cas de perte, venir secourir les banques en injectant des milliards. De plus, les actionnaires seraient propriétaires de sociétés plus stables et moins risquées. Les seuls qui subiraient un impact négatif par une telle décision, seraient les banques elles-mêmes, car cela diminuerait les synergies entre les deux activités. Cependant, elles pourraient continuer à travailler avec des banques d’investissement indépendantes et continuer ainsi à fournir à leur client des prestations qui répondent à leur besoin. Pour effectuer cette séparation, la Confédération peut se baser sur des modèles passés, tels que le Glass-Steagall Act américain ou la loi française 15-45 qui prévoyaient une stricte séparation ou encore le modèle financier chinois qui, grâce à une stricte séparation, est le pays qui a le mieux résisté à la crise financière de 2007. La Suisse peut également s’inspirer de modèles actuels, tels que la réforme Vickers et la loi Volcker qui ont été votées en Angleterre et aux Etats-Unis, après les déboires de leurs banques suite à la crise financière. Ces réformes prévoient de séparer partiellement les activités d’investissement et ainsi de stabiliser sur le long terme le système financier du pays

Early-life adversity accelerates cellular ageing and affects adult inflammation: experimental evidence from the European starling

Early-life adversity is associated with accelerated cellular ageing during development and increased inflammation during adulthood. However, human studies can only establish correlation, not causation, and existing experimental animal approaches alter multiple components of early-life adversity simultaneously. We developed a novel hand-rearing paradigm in European starling nestlings (Sturnus vulgaris), in which we separately manipulated nutritional shortfall and begging effort for a period of 10 days. The experimental treatments accelerated erythrocyte telomere attrition and increased DNA damage measured in the juvenile period. For telomere attrition, amount of food and begging effort exerted additive effects. Only the combination of low food amount and high begging effort increased DNA damage. We then measured two markers of inflammation, high-sensitivity C-reactive protein and interleukin-6, when the birds were adults. The experimental treatments affected both inflammatory markers, though the patterns were complex and different for each marker. The effect of the experimental treatments on adult interleukin-6 was partially mediated by increased juvenile DNA damage. Our results show that both nutritional input and begging effort in the nestling period affect cellular ageing and adult inflammation in the starling. However, the pattern of effects is different for different biomarkers measured at different time points

Closing Remarks: What Was This All About?

Centered on the main question of poetics and poeticity, this volume provides a broad overview of computational methods including motif analysis, network analysis, machine learning, and natural language processing. Without limiting ourselves to poetry, we explore the poetics of various literary productions in verse or in prose, as well as experiments towards the computational generation of poems. The volume is meant to gather a representative set of such approaches, and to offer a space for sharing perspectives, practices, and inspiring insights into the issues, old and new, being addressed by digital literary studies

MRI texture analysis as means for addressing rehydration and milk diffusion in cereals

Cereals microstructure is one of the primary quality attributes of cereals. Cereals rehydration and milk diffusion depends on such microstructure and thus, the crispiness and the texture, which will make it more palatable for the final consumer. Magnetic Resonance Imaging (MRI) is a very powerful tomographic tool since acquisition parameter leads to a wide possibility for identifying textures, structures and liquids mobility. It is suited for noninvasive imaging of water and fats. Rehydration and diffusion cereals processes were measured by MRI at different times and using two different kinds of milk, varying their fat level. Several images were obtained. A combination of textural analysis (based on the analysis of histograms) and segmentation methods (in order to understand the rehydration level of each variety of cereals) were performed. According to the rehydration level, no advisable clustering behaviour was found. Nevertheless, some differences were noticeable between the coating, the type of milk and the variety of cereals