A non-relativistic limit of NS-NS gravity Bergshoeff, E. A.; Lahnsteiner, J.; Romano, L. ...
The journal of high energy physics,
06/2021, Letnik:
2021, Številka:
6
Journal Article
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A
bstract
We discuss a particular non-relativistic limit of NS-NS gravity that can be taken at the level of the action and equations of motion, without imposing any geometric constraints by hand. ...This relies on the fact that terms that diverge in the limit and that come from the Vielbein in the Einstein-Hilbert term and from the kinetic term of the Kalb-Ramond two-form field cancel against each other. This cancelling of divergences is the target space analogue of a similar cancellation that takes place at the level of the string sigma model between the Vielbein in the kinetic term and the Kalb-Ramond field in the Wess-Zumino term. The limit of the equations of motion leads to one equation more than the limit of the action, due to the emergence of a local target space scale invariance in the limit. Some of the equations of motion can be solved by scale invariant geometric constraints. These constraints define a so-called Dilatation invariant String Newton-Cartan geometry.
The European Lead Extraction ConTRolled Registry (ELECTRa), is a prospective registry of consecutive transvenous lead extraction (TLE) procedures conducted by the European Heart Rhythm Association ...(EHRA) in order to identify the safety and efficacy of the current practice of TLE.
European centres performing TLE, invited by the organizing committee on behalf of EHRA, prospectively recruited all consecutive patients undergoing TLE at their institution. The primary endpoint was TLE safety defined by pre-discharge major procedure-related complications including death. Secondary endpoints included clinical and radiological success and overall complication rates. Outcomes were compared between Low Volume (LoV) vs. High Volume (HiV) centers (LoV < 30 and HiV ≥ 30 procedures/year). A total of 3555 consecutive patients (pts) of whom 3510 underwent TLE at 73 centres in 19 European countries were enrolled between November 2012 and May 2014. The primary endpoint of in-hospital procedure-related major complication rate was 1.7% 95% CI 1.3-2.1% (58/3510 pts) including a mortality of 0.5% 95% CI 0.3-0.8% (17/3510 pts). Approximately two-thirds (37/58) of these complications occurred during the procedure and one-third (21/58) in the post-operative period. The most common procedure related complications were those requiring pericardiocentesis or chest tube and/or surgical repair (1.4% 95% CI 1.0-1.8%). Complete clinical and radiological success rates were 96.7% 95% CI 96.1-97.3% and 95.7% 95% CI 95.2-96.2%, respectively. The all cause in-hospital major complications and deaths were significantly lower in HiV centres vs. LoV centres (2.4% 95% CI 1.9-3.0% vs. 4.1% 95% CI 2.7-6.0%, P = 0.0146; and 1.2% 95% CI 0.8-1.6% vs. 2.5% 95% CI 1.5-4.1% P = 0.0088), although those related to the procedure did not reach statistical significance. Radiological and clinical successes were more frequent in HiV vs. LoV centres.
The ELECTRa study is the largest prospective registry on TLE and confirmed the safety and efficacy of the current practice of TLE. Lead extraction was associated with a higher success rate with lower all cause complication and mortality rates in high volume compared with low volume centres.
A
bstract
We construct a non-relativistic limit of ten-dimensional
N
= 1 supergravity from the point of view of the symmetries, the action, and the equations of motion. This limit can only be ...realized in a supersymmetric way provided we impose by hand a set of geometric constraints, invariant under all the symmetries of the non-relativistic theory, that define a so-called ‘self-dual’ Dilatation-invariant String Newton-Cartan geometry. The non-relativistic action exhibits three emerging symmetries: one local scale symmetry and two local conformal supersymmetries. Due to these emerging symmetries the Poisson equation for the Newton potential and two partner fermionic equations do not follow from a variation of the non-relativistic action but, instead, are obtained by a supersymmetry variation of the other equations of motion that do follow from a variation of the non-relativistic action. We shortly discuss the inclusion of the Yang-Mills sector that would lead to a non-relativistic heterotic supergravity action.
A
bstract
We construct the basic Neveu-Schwarz (NS) brane solutions of non-relativistic string theory using longitudinal T-duality as a solution generating technique. Extending the NS background ...fields to a supergravity multiplet, we verify that all solutions we find are half-supersymmetric. The two perturbative solutions we find both have an interpretation as the background geometry outside a string-like object. Correspondingly, we refer to these non-Lorentzian backgrounds as winding string and unwound string solution. Whereas the winding string is part of the on-shell spectrum of non-relativistic string theory, the unwound string only makes sense off-shell where it mediates the instantaneous gravitational force. Seen from the nine-dimensional point of view, we find that the winding string solution is sourced by a non-relativistic massive particle and that the unwound string solution is sourced by a massless Galilean particle of zero colour and spin. We explain how these two string solutions fit into a discrete lightcone quantization of string theory. We shortly discuss the basic NS five-brane and Kaluza-Klein monopole solutions and show that they are both half-supersymmetric.
Stars are generally spherical, yet their gaseous envelopes often appear nonspherical when ejected near the end of their lives. This quirk is most notable during the planetary nebula phase, when these ...envelopes become ionized. Interactions among stars in a binary system are suspected to cause the asymmetry. In particular, a precessing accretion disk around a companion is believed to launch point-symmetric jets, as seen in the prototype Fleming 1. Our finding of a post-common-envelope binary nucleus in Fleming 1 confirms that this scenario is highly favorable. Similar binary interactions are therefore likely to explain these kinds of outflows in a large variety of systems.
The 1805 earthquake damaged a large area of the Southern Italy, destroying most of the architectural heritage in the “Contado of Molise”, a poor region characterized by numerous medieval towns. In ...the aftermath of the catastrophe, the reconstruction and in fewer cases the restoration of important buildings, mainly the ecclesiastical ones, took place without a well-defined rebuilding plan. If, from a formal point of view, interesting design levels were not reached, the same cannot be stated for the construction solutions adopted, especially regarding vaulted systems. Actually, they were conceived either with wood, concrete with aggregates or full/hollow clay bricks. This variety of constructive raw elements is a direct manifestation of the richness of the vernacular constructive tradition. Moreover, the intrinsic lightness of such materials suggests as well the need at the time of new lightweight structures capable of standing on pre-existing weakened masonries. This approach was probably taken in order to reduce vulnerability and improve structural resilience to earthquakes. In light of these considerations, the paper focuses on the different construction techniques used to rebuild the vaulting systems after the 1805 earthquake in Molise, discussing their potentialities and weaknesses as well as their capacity to improve resilience in the architectural heritage.
ABSTRACT The discrepancy between abundances computed using optical recombination lines and collisionally excited lines is a major unresolved problem in nebular astrophysics. Here, we show that the ...largest abundance discrepancies are reached in planetary nebulae with close binary central stars. We illustrate this using deep spectroscopy of three nebulae with a post common-envelope (CE) binary star. Abell 46 and Ou 5 have O2+/H+ abundance discrepancy factors larger than 50, and as high as 300 in the inner regions of Abell 46. Abell 63 has a smaller discrepancy factor around 10, which is still above the typical values in ionized nebulae. Our spectroscopic analysis supports previous conclusions that, in addition to "standard" hot ( ∼ 104 K) gas, there exists a colder ( ∼ 103 K), ionized component that is highly enriched in heavy elements. These nebulae have low ionized masses, between 10−3 and 10−1 M depending on the adopted electron densities and temperatures. Since the much more massive red giant envelope is expected to be entirely ejected in the CE phase, the currently observed nebulae would be produced much later, during post-CE mass loss episodes when the envelope has already dispersed. These observations add constraints to the abundance discrepancy problem. We revise possible explanations. Some explanations are naturally linked to binarity such as, for instance, high-metallicity nova ejecta, but it is difficult at this stage to depict an evolutionary scenario consistent with all of the observed properties. We also introduce the hypothesis that these nebulae are the result of tidal destruction, accretion, and ejection of Jupiter-like planets.
Studying the genetic basis of gene expression and chromatin organization is key to characterizing the effect of genetic variability on the function and structure of the human genome. Here we unravel ...how genetic variation perturbs gene regulation using a dataset combining activity of regulatory elements, gene expression, and genetic variants across 317 individuals and two cell types. We show that variability in regulatory activity is structured at the intra- and interchromosomal levels within 12,583 cis-regulatory domains and 30 trans-regulatory hubs that highly reflect the local (that is, topologically associating domains) and global (that is, open and closed chromatin compartments) nuclear chromatin organization. These structures delimit cell type-specific regulatory networks that control gene expression and coexpression and mediate the genetic effects of cis- and trans-acting regulatory variants on genes.
ABSTRACT We present the discovery of a 3h5m orbital-period binary star at the heart of the planetary nebula M 3-1 – the shortest period photometrically variable central star known and second only to ...V458 Vul, in general. Combined modelling of light and radial velocity curves reveals both components to be close to Roche lobe filling, strongly indicating that the central star will rapidly evolve to become a cataclysmic variable, perhaps experiencing a similar evolution to V458 Vul resulting in a nova eruption before the planetary nebula has fully dissipated. While the short orbital period and near Roche lobe filling natures of both components make the central binary of M 3-1 an important test case with which to constrain the formation processes of cataclysmic variables, novae, and perhaps even supernovae type Ia.
ABSTRACT
Recent studies have indicated that triple-star systems may play a role in the formation of an appreciable number of planetary nebulae, however, only one triple central star is known to date ...(and that system is likely too wide to have had much influence on the evolution of its component stars). Here, we consider the possibility that Sh 2-71 was formed by a triple system that has since broken apart. We present the discovery of two regions of emission, seemingly aligned with the proposed tertiary orbit (i.e. in line with the axis formed by the two candidate central star systems previously considered in the literature). We also perform a few simple tests of the plausibility of the triple hypothesis based on the observed properties (coordinates, radial velocities, distances, and proper motions) of the stars observed close to the projected centre of the nebula, adding further support through numerical integrations of binary orbits responding to mass loss. Although a number of open questions remain, we conclude that Sh 2-71 is currently one of the best candidates for planetary nebula formation influenced by triple-star interactions.
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