bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relativistic and Newtonian Shock Breakouts
Authors: Nakar Ehud 
Published: September 2012

AbstractObservations of the first light from a stellar explosion can open a window to a wealth of information on the progenitor system and the explosion itself. Here I briefly discuss the theoretical expectation of that emission, comparing Newtonian and relativistic breakouts. The former takes place in regular core-collapse supernovae (SNe) while the latter is expected in SNe that are associated with gamma-ray bursts (GRBs), extremely energetic SNe (e.g., SN2007bi) and white dwarf explosions (e.g., type Ia and .Ia SNe, accretion induced collapse). I present the characteristic observable signatures of both types of breakouts, when spherical. Finally, I discuss Newtonian shock breakouts through wind, which produce a very luminous signal, with an X-ray component that is weak around the breakout, and becomes brighter afterwards.
Population III Gamma-Ray Burst
Authors: Ioka Kunihito , Suwa Yudai , Nagakura Hiroki , de Souza Rafael S. , Yoshida Naoki 
Published: September 2012

AbstractGamma-ray bursts (GRBs) are unique probes of the first generation (Pop III) stars. We show that a relativistic gamma-ray burst (GRB) jet can potentially pierce the envelope of a very massive Pop III star even if the Pop III star has a supergiant hydrogen envelope without mass loss, thanks to the long-lived powerful accretion of the envelope itself. While the Pop III GRB is estimated to be energetic (Eγ,iso ~ 1055 erg), the supergiant envelope hides the initial bright phase in the cocoon component, leading to a GRB with a long duration ~1000 (1 + z) s and an ordinary isotropic luminosity ~ 1052 erg s−1 (~ 10−9 erg cm−2 s−1 at redshift z ~ 20), although these quantities are found to be sensitive to the core and envelope mass. We also show that Pop III.2 GRBs (which are primordial but affected by radiation from other stars) occur >100 times more frequently than Pop III.1 GRBs, and thus should be suitable targets for future X-ray and radio missions. The radio transient surveys are already constraining the Pop III GRB rate and promising in the future.
On the Origin of the 6.4 keV line from the GRXE
Authors: Eze Romanus , Saitou Kei , Ebisawa Ken 
Published: September 2012

AbstractThe Galactic Ridge X-ray Emission (GRXE) spectrum has strong iron emission lines at 6.4, 6.7, and 7.0 keV, each corresponding to the neutral (or low-ionized), He-like, and H-like iron ions. The 6.4 keV fluorescence line is due to irradiation of neutral (or low ionized) material (iron) by hard X-ray sources, indicating uniform presence of the cold matter in the Galactic plane. In order to resolve origin of the cold fluorescent matter, we examined the contribution of the 6.4 keV line emission from white dwarf surfaces in the hard X-ray emitting symbiotic stars (hSSs) and magnetic cataclysmic variables (mCVs) to the GRXE. In our spectral analysis of 4 hSSs and 19 mCVs observed with Suzaku, we were able to resolve the three iron emission lines. We found that the equivalent-widths (EWs) of the 6.4 keV lines of hSSs are systematically higher than those of mCVs, such that the average EWs of hSSs and mCVs are 180−10+50 eV and 93−3+20 eV, respectively. The EW of hSSs compares favorably with the typical EWs of the 6.4 keV line in the GRXE of 90–300 eV depending on Galactic positions. Average 6.4 keV line luminosities of the hSSs and mCVs are 9.2 × 1039 and 1.6 × 1039 photons s−1, respectively, indicating that hSSs are intrinsically more efficient 6.4 keV line emitters than mCVs. We estimated required space densities of hSSs and mCVs to account for all the GRXE 6.4 keV line emission flux to be 2 × 10−7 pc−3 and 1 × 10−6 pc−3, respectively. We also estimated the actual 6.4 keV line contribution from the hSSs, which is as much as 30% of the observed GRXE flux, and that from the mCV is about 50%. We therefore conclude that the GRXE 6.4 keV line flux is primarily explained by hSSs and mCVs.
Turbulent Magnetic Field Amplification behind Strong Shock Waves in GRB and SNR
Authors: Inoue Tsuyoshi 
Published: September 2012

AbstractUsing three-dimensional (special relativistic) magnetohydrodynamics simulations, the amplification of magnetic field behind strong shock wave is studied. In supernova remnants and gamma-ray bursts, strong shock waves propagate through an inhomogeneous density field. When the shock wave hit a density bump or density dent, the Richtmyer-Meshkov instability is induced that cause a deformation of the shock front. The deformed shock leaves vorticity behind the shock wave that amplifies the magnetic field due to the stretching of field lines.
Neutrino-driven supernova explosions powered by nuclear reactions
Authors: Nakamura K. , Takiwaki T. , Kotake K. , Nishimura N. 
Published: September 2012

AbstractWe have investigated the revival of a shock wave by nuclear burning reactions at the central region of core-collapse supernovae. For this purpose, we performed hydrodynamic simulations of core collapse and bounce for 15 M⊙ progenitor model, using ZEUS-MP code in axi-symmetric coordinates. Our numerical code is equipped with a simple nuclear reaction network including 13 α nuclei form 4He to 56Ni, and accounting for energy feedback from nuclear reactions as well as neutrino heating and cooling. We found that the energy released by nuclear reactions is significantly helpful in accelerating shock waves and is able to produce energetic explosion even if the input neutrino luminosity is low.
Study of very early phase GRB afterglows with MITSuME
Authors: Saito Yoshihiko , Yatsu Yoichi , Nakajima Hideya , Kawai Nobuyuki , Asano Katsuaki , Aoki Yu , Hayashi Mayumi , Song Seongdeng , Kawakami Kosuke , Tokoyoda Kazuki , Enomoto Takahiro , Usui Ryuichi , Kuroda Daisuke , Yanagisawa Kenshi , Shimizu Hiroyasu , Toda Hiroyuki , Nagayama Shogo , Hanayama Hidekazu , Yoshida Michitoshi , Ohta Koji 
Published: September 2012

AbstractWe review the results of very early phase optical follow-up observations of recent gamma-ray bursts (GRBs) with the multi-color optical telescopes “MITSuME”. The MITSuME telescopes were designed to perform “real time” and “automatic” follow-up observations prompted by the GCN alerts via the Internet. The rapidly slewing equatorial mounts allow MITSuME to start photometric observations within 100 seconds after the trigger for several GRBs. In particular, we detected a brightening just after the trigger for two GRBs. These phenomena could be interpreted as the “on-set” of afterglow. In this paper we summarize these optical observations with a brief interpretation.
Evolution of stars just below the critical mass for iron core formation
Authors: Takahashi Koh , Umeda Hideyuki , Yoshida Takashi 
Published: September 2012

AbstractWe calculate the evolution of stars with their initial mass of 9-11M⊙ under very fine initial mass grid of 0.01M⊙. We determine the lower critical mass for Ne ignition in an ONe core that has not undergone the thermal pulse episode. The values are 9.83M⊙ for the initial mass and 1.365M⊙ for the CO core mass. A star with an initial mass slightly larger than the critical, undergoes an off-center Ne+O ignition. Since the energy production rate of Ne+O burning and lasting electron capture reactions is sufficiently large to ignite Si, an Fe core forms as a result of shell Si burning. For a star just below the critical mass, an ONe core continues to contract. In such a high density core, electron capture by nuclei produced through C burning affects the core evolution. After 20Ne starts to capture electrons, the core may ignite O and undergo O detonation. The fate may be an Electron Capture Supernova.
3D hydrodynamic core-collapse SN simulations for an 11.2 M⊙ star with spectral neutrino transport
Authors: Takiwaki Tomoya , Kotake Kei , Suwa Yudai 
Published: September 2012

AbstractWe have performed three-dimensional (3D) hydrodynamical simulations of core-collapse supernovae (SNe) with multigroup neutrino transport to study non-axisymmetric effects in the context of neutrino heating explosion mechanism. By comparing one- (1D) and two dimensional (2D) results with those of 3D, we study how the increasing spatial multi-dimensionality affects the postbounce SN dynamics. The calculations were performed with an energy-dependent treatment of the neutrino transport that is solved by the isotropic diffusion source approximation scheme. In agreement with previous studies, our 1D model does not produce explosions for the 11.2 M⊙ star, while the neutrino-driven revival of the stalled bounce shock is obtained both in the 2D and 3D models. Our results show that convective matter motions below the gain radius become much more violent in 3D than 2D, making the neutrino luminosity larger for 3D. Enhanced by the large neutrino luminosity, the shock of the 3D model expands faster than that of the 2D. Our results show that the evolution of the shock is sensitive to the employed numerical resolutions. To draw a robust conclusion, 3D simulations with much higher numerical resolution and more advanced treatment of neutrino transport and gravity is needed.
GRB 100816A and the nature of intermediate duration gamma-ray bursts
Authors: Tunnicliffe Rachel L. , Levan Andrew 
Published: September 2012

AbstractGamma-ray bursts are normally split into two classes, primarily determined by their observed duration, so called long (> 2s) and short (< 2s) GRBs. There have been many claims of a third duration class, with emission lasting for intermediate periods between 2 - 5s, although the reality of this class remains controversial. Here, we investigate this further utilising the 2.9s duration, spectrally hard GRB 100816A. This burst lies well offset from its host galaxy, has no evidence for an associated supernova (albeit to only moderately constraining limits), and has properties which appear to be genuinely intermediate between long- and short- population bursts. We extend this analysis by comparing the physical locations of a population of intermediate duration GRBs with those of short-GRBs and long-GRBs, concluding that the intermediate sample is indistinguishable from the long-GRB population, whose locations are very different from other transients.
Classification of long Gamma Ray Bursts using cosmologically corrected temporal estimators
Authors: Vasquez Nicolas A. , Vasconez Christian 
Published: September 2012

AbstractThe canonical classification of GRBs establishes two types of bursts, long and short. Although an intermediate class of GRBs was suggested, its existence is not yet conclusive. In the present work, we explore the temporal classification of GRBs in the burst frame, because in recent years the statistics of bursts with known redshifts has increased. We studied a sample of Swift GRBs with known redshifts to determine three different time estimators: autocorrelation functions, emission times and duration times. In order to look for a subclass in long GRBs, we studied the distribution of the cosmologically corrected time estimators. The distribution of time estimators of the sample suggests an internal division of long GRBs. The proposed bimodality is also supported in the isotropic luminosity - time estimator planes and we discuss some possible implications of the classification of GRBs in the burst frame.
Structure Formation and Characterization in Supernova Explosions
Authors: Young Patrick A. , Ellinger Carola , Fryer Chris , Rockefeller Gabe 
Published: September 2012

AbstractObservations of supernova remnants show that large- and small scale structures form at various points in the explosion. We present a case study of structure formation in 3D in a 15 M⊙ supernova for different parameters. We investigate the structure formation and morphology of the Rayleigh-Taylor unstable region. We also propose a method of characterizing the sizes of overdense clumps that can be compared directly with observations. The RT instabilities result in clumps that are overdense by 1-2 orders of magnitude with respect to the ambient gas, have size scales on the level of a few% of the remnant diameter, and are not diffused after the first ~30 yrs of the remnant evolution, in the absence of a surrounding medium.
THE UBIQUITY OF CONSERVATIVE TRANSLATIONS
Authors: JEŘÁBEK EMIL 
Published: September 2012

AbstractWe study the notion of conservative translation between logics introduced by (Feitosa & D’Ottaviano2001). We show that classical propositional logic (CPC) is universal in the sense that every finitary consequence relation over a countable set of formulas can be conservatively translated into CPC. The translation is computable if the consequence relation is decidable. More generally, we show that one can take instead of CPC a broad class of logics (extensions of a certain fragment of full Lambek calculus FL) including most nonclassical logics studied in the literature, hence in a sense, (almost) any two reasonable deductive systems can be conservatively translated into each other. We also provide some counterexamples, in particular the paraconsistent logic LP is not universal.
Uncovering the nonadiabatic response of geosynchronous electrons to geomagnetic disturbance
Authors: Gannon J. L. , Elkington S. R. , Onsager T. G. 
Published: September 2012

We describe an energy spectrum method for scaling electron integral flux, which is measured at a constant energy, to phase space density at a constant value of the first adiabatic invariant which removes much of the variation due to reversible adiabatic effects. Applying this method to nearly a solar cycle (1995–2006) of geosynchronous electron integral flux (E > 2.0 MeV) from the GOES satellites, we see that much of the diurnal variation in electron phase space density at constant energy can be removed by the transformation to phase space density at constant μ (4000 MeV/G). This allows us a clearer picture of underlying nonadiabatic electron population changes due to geomagnetic activity. Using scaled phase space density, we calculate the percentage of geomagnetic storms resulting in an increase, decrease, or no change in geosynchronous electrons as 38%, 7%, and 55%, respectively. We also show examples of changes in the electron population that may be different from the unscaled fluxes alone suggest. These examples include sudden electron enhancements during storms which appear during the peak of negative Dst for μ‐scaled phase space density, contrary to the slow increase seen during the recovery phase for unscaled phase space density for the same event.
Hydrogeomorphology of the hyporheic zone: Stream solute and fine particle interactions with a dynamic streambed
Authors: Harvey J. W. , Drummond J. D. , Martin R. L. , McPhillips L. E. , Packman A. I. , Jerolmack D. J. , Stonedahl S. H. , Aubeneau A. F. , Sawyer A. H. , Larsen L. G. , Tobias C. R. 
Published: September 2012

Hyporheic flow in streams has typically been studied separately from geomorphic processes. We investigated interactions between bed mobility and dynamic hyporheic storage of solutes and fine particles in a sand‐bed stream before, during, and after a flood. A conservatively transported solute tracer (bromide) and a fine particles tracer (5 μm latex particles), a surrogate for fine particulate organic matter, were co‐injected during base flow. The tracers were differentially stored, with fine particles penetrating more shallowly in hyporheic flow and retained more efficiently due to the high rate of particle filtration in bed sediment compared to solute. Tracer injections lasted 3.5 h after which we released a small flood from an upstream dam one hour later. Due to shallower storage in the bed, fine particles were rapidly entrained during the rising limb of the flood hydrograph. Rather than being flushed by the flood, we observed that solutes were stored longer due to expansion of hyporheic flow paths beneath the temporarily enlarged bedforms. Three important timescales determined the fate of solutes and fine particles: (1) flood duration, (2) relaxation time of flood‐enlarged bedforms back to base flow dimensions, and (3) resulting adjustments and lag times of hyporheic flow. Recurrent transitions between these timescales explain why we observed a peak accumulation of natural particulate organic matter between 2 and 4 cm deep in the bed, i.e., below the scour layer of mobile bedforms but above the maximum depth of particle filtration in hyporheic flow paths. Thus, physical interactions between bed mobility and hyporheic transport influence how organic matter is stored in the bed and how long it is retained, which affects decomposition rate and metabolism of this southeastern Coastal Plain stream. In summary we found that dynamic interactions between hyporheic flow, bed mobility, and flow variation had strong but differential influences on base flow retention and flood mobilization of solutes and fine particulates. These hydrogeomorphic relationships have implications for microbial respiration of organic matter, carbon and nutrient cycling, and fate of contaminants in streams.
Stress imparted by the great 2004 Sumatra earthquake shut down transforms and activated rifts up to 400 km away in the Andaman Sea
Authors: Sevilgen Volkan , Stein Ross S. , Pollitz Fred F. 
Published: September 2012

The origin and prevalence of triggered seismicity and remote aftershocks are under debate. As a result, they have been excluded from probabilistic seismic hazard assessment and aftershock hazard notices. The 2004M = 9.2 Sumatra earthquake altered seismicity in the Andaman backarc rift-transform system. Here we show that over a 300-km-long largely transform section of the backarc,M≥4.5 earthquakes stopped for five years, and over a 750-km-long backarc section, the rate of transform events dropped by two-thirds, while the rate of rift events increased eightfold. We compute the propagating dynamic stress wavefield and find the peak dynamic Coulomb stress is similar on the rifts and transforms. Long-period dynamic stress amplitudes, which are thought to promote dynamic failure, are higher on the transforms than on the rifts, opposite to the observations. In contrast to the dynamic stress, we calculate that the mainshock brought the transform segments approximately 0.2 bar (0.02 MPa) farther from static Coulomb failure and the rift segments approximately 0.2 bar closer to static failure, consistent with the seismic observations. This accord means that changes in seismicity rate are sufficiently predictable to be included in post-mainshock hazard evaluations.
Ankle brachial index as an independent predictor of mortality in anticoagulated atrial fibrillation
Authors: Gallego Pilar , Roldán Vanessa , Marín Francisco , Jover Eva , Manzano‐Fernández Sergio , Valdés Mariano , Vicente Vicente , Lip Gregory Y. H. 
Published: September 2012

Eur J Clin Invest 2012; 42 (12): 1302–1308AbstractBackground  An abnormal ankle brachial index (ABI, the ratio of the ankle and the brachial systolic blood pressure) (≤ 0·90 or ≥ 1·4) suggests the presence of peripheral arterial disease (PAD) and has proposed as a marker of cardiovascular risk. We hypothesised that the ABI would predict mortality and adverse events in anticoagulated chronic nonvalvular AF patients.Methods  We recruited 287 consecutive anticoagulated outpatients with permanent or paroxysmal nonvalvular AF who were stabilised for 6 months on oral anticoagulation (Oral anticoagulation; INR 2·0–3·0). ABI was performed following a standard technique. Cox models were used to determine the association between ABI, and bleeding, cardiovascular events and mortality.Results  Median ABI was 1·09 (0·93–1·23) and 78 (27%) had an abnormal ABI. Abnormal ABI was associated with diabetes, heart failure and ischaemic heart disease (P = 0·006, 0·019 and 0·009, respectively), and a CHADS2 score ≥ 2 (P = 0·016). Median follow‐up was 861 (718–1016) days, during 21(7%) presented an adverse cardiovascular event, 23 (8%) major bleeding events and 18 (6%) died. ABI was an independent predictor for all‐cause mortality, even after adjusting for CHADS2 score (Cox multivariable regression analysis, HR 2·76(1·08–7·06), P = 0·033). Abnormal ABI was significantly associated with major haemorrhagic events [HR: 2·47(1·01–6·04); P = 0·047], even after adjustment for HAS‐BLED score.Conclusion  Abnormal ABI is common in AF patients, and ABI was an independent predictor for all‐cause mortality, even after adjusting for CHADS2 score. ABI was an independent predictor for major bleeding, even after adjusting for the HAS‐BLED score. ABI could be a useful tool for improving risk stratification of anticoagulated AF patients.
Egg size and composition in an ageing capital breeder – consequences for offspring performance
Authors: PÖYKKÖ HEIKKI , MÄNTTÄRI SATU 
Published: September 2012

1. Egg size is often used as a proxy of egg quality although size and composition may vary, e.g. in insects egg size usually decreases as female ages. Whether this decrease in size reflects reduced concentrations of essential nutrients such as lipids and proteins of eggs laid by ageing females, or does reduced size per se explain often observed lower fitness of later laid eggs is poorly explored.2. Egg properties were compared with fitness parameters of offspring laid on the first and fourth night during the oviposition period of a capital breeding moth, Cleorodes lichenaria (Hufnagel). The study aim was to explore whether decreased egg size is caused by decreased provisioning into later laid eggs measured as egg protein and lipid concentration, and whether it results in lower fitness of later laid offspring.3. The fresh and dry weight of eggs decreased over the oviposition period, but the protein and lipid concentration remained constant. Survival of larvae was lower among the fourth night laid offspring on a low quality host Parmelia sulcata Taylor compared to a high quality host Ramalina fraxinea (L.) Ach. No differences were observed in egg fertility or hatchability, neonate survival without food and pupal mass between the offspring produced on different nights.4. Decreased survival of offspring produced later was rather attributable to absolute provisioning (i.e. lower weight of eggs) than relative provisioning (i.e. decreased concentrations of nutrients in eggs). It is argued that lower survival of later laid smaller eggs on low quality diet is likely attributable to physical and chemical characteristics of host lichens and/or physical properties of tiny neonate larvae.
Advances with vaccination against Neisseria meningitidis
Authors: Borrow Ray 
Published: September 2012

AbstractIn the last decade, meningococcal serogroup C conjugate vaccination programs have been demonstrated to be hugely successful with a truly impressive public health impact. In sub‐Saharan Africa, with the implementation of an affordable serogroup A conjugate vaccine, it is hoped that a similar public health impact will be demonstrated. Challenges still remain in the quest to develop and implement broadly protective vaccines against serogroup B disease. New, broad coverage vaccines against serogroup B are for the first time becoming available although little is known about their antibody persistence, effectiveness or effect on nasopharyngeal carriage. Enhanced surveillance following any potential vaccine introduction against serogroup B needs to be thoroughly implemented. The future now holds a distinct possibility, globally, for substantially decreasing meningococcal disease, regardless of infecting serogroup.
Requirement for cardiac telemetry during intravenous phenytoin infusion: guideline fact or guideline fiction?
Authors: Siebert W. J. , McGavigan A. D. 
Published: September 2012

AbstractGuidelines recommend the use of cardiac telemetry when phenytoin is administered intravenously. Clinical areas where telemetry is available may not always be the most suitable place to monitor and treat these sick patients. We sought to clarify the evidence regarding the need for cardiac telemetry during intravenous infusion of phenytoin.