1,784 research outputs found
GRB Afterglows from Anisotropic Jets
Some progenitor models of gamma-ray bursts (GRBs) (e.g., collapsars) may
produce anisotropic jets in which the energy per unit solid angle is a
power-law function of the angle (). We calculate light
curves and spectra for GRB afterglows when such jets expand either in the
interstellar medium or in the wind medium. In particular, we take into account
two kinds of wind: one () possibly from a typical red
supergiant star and another () possibly from a Wolf-Rayet
star. We find that in each type of medium, one break appears in the late-time
afterglow light curve for small but becomes weaker and smoother as
increases. When , the break seems to disappear but the afterglow decays
rapidly. Thus, one expects that the emission from expanding, highly anisotropic
jets provides a plausible explanation for some rapidly fading afteglows whose
light curves have no break. We also present good fits to the optical afterglow
light curve of GRB 991208. Finally, we argue that this burst might arise from a
highly anisotropic jet expanding in the wind () from a red
supergiant to interpret the observed radio-to-optical-band afterglow data
(spectrum and light curve).Comment: 12 pages + 10 figures, accepted by Ap
Dynamical Equilibration Across a Quenched Phase Transition in a Trapped Quantum Gas
The formation of an equilibrium quantum state from an uncorrelated thermal
one through the dynamical crossing of a phase transition is a central question
of non-equilibrium many-body physics. During such crossing, the system breaks
its symmetry by establishing numerous uncorrelated regions separated by
spontaneously-generated defects, whose emergence obeys a universal scaling law
with the quench duration. Much less is known about the ensuing re-equilibrating
or "coarse-graining" stage, which is governed by the evolution and interactions
of such defects under system-specific and external constraints. In this work we
perform a detailed numerical characterization of the entire non-equilibrium
process, addressing subtle issues in condensate growth dynamics and
demonstrating the quench-induced decoupling of number and coherence growth
during the re-equilibration process. Our unique visualizations not only
reproduce experimental measurements in the relevant regimes, but also provide
valuable information in currently experimentally-inaccessible regimes.Comment: Supplementary Movie Previes: SM-Movie-1: https://youtu.be/3q7-CvuBylg
SM-Movie-2: https://youtu.be/-Gymaiv9rC0 SM-Movie-3:
https://youtu.be/w-O2SPiw3nE SM-Movie-4: https://youtu.be/P4xGyr4dwK
Modeling GRB 050904: Autopsy of a Massive Stellar Explosion at z=6.29
GRB 050904 at redshift z=6.29, discovered and observed by Swift and with
spectroscopic redshift from the Subaru telescope, is the first gamma-ray burst
to be identified from beyond the epoch of reionization. Since the progenitors
of long gamma-ray bursts have been identified as massive stars, this event
offers a unique opportunity to investigate star formation environments at this
epoch. Apart from its record redshift, the burst is remarkable in two respects:
first, it exhibits fast-evolving X-ray and optical flares that peak
simultaneously at t~470 s in the observer frame, and may thus originate in the
same emission region; and second, its afterglow exhibits an accelerated decay
in the near-infrared (NIR) from t~10^4 s to t~3 10^4 s after the burst,
coincident with repeated and energetic X-ray flaring activity. We make a
complete analysis of available X-ray, NIR, and radio observations, utilizing
afterglow models that incorporate a range of physical effects not previously
considered for this or any other GRB afterglow, and quantifying our model
uncertainties in detail via Markov Chain Monte Carlo analysis. In the process,
we explore the possibility that the early optical and X-ray flare is due to
synchrotron and inverse Compton emission from the reverse shock regions of the
outflow. We suggest that the period of accelerated decay in the NIR may be due
to suppression of synchrotron radiation by inverse Compton interaction of X-ray
flare photons with electrons in the forward shock; a subsequent interval of
slow decay would then be due to a progressive decline in this suppression. The
range of acceptable models demonstrates that the kinetic energy and circumburst
density of GRB 050904 are well above the typical values found for low-redshift
GRBs.Comment: 45 pages, 7 figures, and ApJ accepted. Revised version, minor
modifications and 1 extra figur
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Reliable Cost Prediction and Control for Intelligent Manufacture: A Key Performance Indicator Perspective
Data Availability Statement: Not applicable. Acknowledgments: We would like to thank Primal Electro for providing the industrial data.Intelligent manufacturing is facing significant challenges in adapting to the ever-changing equipment, instrumentation, process and economics. Such a trend together with the pressure to reliably control and contain production costs means that frequent adjusting decisions are required to adapt to incessant volatility imposed on manufacturing systems. Under this circumstance, cost-effective and quality-guaranteed manufacturing strategies would be the most logical route to reducing production costs. In this paper, a novel dynamical cost prediction and control (CPC) model is proposed to support collective decision-making in intelligent manufacturing, where the model output is the real-time prediction of possible manufacturing costs, while the inputs are generic manufacturing key performance indicators covering inventory, product quality, production efficiency, resource utilisation and environmental impact. This proposed CPC model distinguishes itself from existing ones for its capability to translate manufacturing data (at both the physical level and operation management level) into financial metrics that contribute to forming a common language between engineering, financial and administrative departments of an enterprise. The case study about the assembly line of optoelectronic devices demonstrates that, although different enterprise departments have different priorities, our CPC model helps them to achieve certain consensus on intended production that finally creates satisfactory profitability for the company at controlled manufacturing costs.Natural Science Foundation of Sichuan Province of China under Grant 23NSFSC1427; National Natural Science Foundation of China under Grants U2330206, U2230206, 62173068l European Union’s Horizon 2020 Research and Innovation Programme under Grant 820677 (IQONIC)
Triethylammonium N′-(benzylsulfanylthiocarbonyl)-2-hydroxybenzohydrazidate
In the title compound, C6H16N+·C15H13N2O2S2
−, the thione S atom is in a cis configuration with respect to the phenyl and benzene rings, while it adopts a trans configuration with respect to the carbonyl group. The dihedral angle between the benzene and phenyl rings is 78.81 (2)°. The molecular conformation is stabilized by intramolecular O—H⋯O and N—H⋯S hydrogen bonds, while intermolecular N—H⋯O, N—H⋯N and weak C—H⋯O interactions help to stabilize the crystal structure
The revival-collapse phenomenon in the quadrature field components of the two-mode multiphoton Jaynes-Cummings model
In this paper we consider a system consisting of a two-level atom in an
excited state interacting with two modes of a radiation field prepared
initially in -photon coherent states. This system is described by two-mode
multiphoton (, i.e., ) Jaynes-Cummings model (JCM). For this system
we investigate the occurrence of the revival-collapse phenomenon (RCP) in the
evolution of the single-mode, two-mode, sum and difference quadrature
squeezing. We show that there is a class of states for which all these types of
squeezing exhibit RCP similar to that involved in the corresponding atomic
inversion. Also we show numerically that the single-mode squeezing of the first
mode for provides RCP similar to that of the atomic inversion
of the case , however, sum and difference squeezing give
partial information on that case. Moreover, we show that single-mode, two-mode
and sum squeezing for the case provide information on the
atomic inversion of the single-mode two-photon JCM. We derive the rescaled
squeezing factors giving accurate information on the atomic inversion for all
cases. The consequences of these results are that the homodyne and heterodyne
detectors can be used to detect the RCP for the two-mode JCM.Comment: 18 pages, 6 figure
Cosmopolitan Risk Community and China's Climate Governance
Ulrich Beck asserts that global risks, such as climate change, generate a form of ‘compulsory cosmopolitanism’, which ‘glues’ various actors into collective action. Through an analysis of emerging ‘cosmopolitan risk communities’ in Chinese climate governance, this paper points out a ‘blind spot’ in the theorisation of cosmopolitan belonging and an associated inadequacy in explaining shifting power-relations. The paper addresses this problem by engaging with the intersectionality of the cosmopolitan space. It is argued that cosmopolitan belonging is a form of performative identity. Its key characteristic lies in a ‘liberating prerogative’, which enables individuals to participate in the solution of common problems creatively. It is this liberating prerogative that coerces the state out of political monopoly and marks the cosmopolitan moment
Proposal for measurment of harmonic oscillator Berry phase in ion traps
We propose a scheme for measuring the Berry phase in the vibrational degree
of freedom of a trapped ion. Starting from the ion in a vibrational coherent
state we show how to reverse the sign of the coherent state amplitude by using
a purely geometric phase. This can then be detected through the internal
degrees of freedom of the ion. Our method can be applied to preparation of
Schr\"odinger cat states.Comment: Replaced with revised versio
First measurements of spin correlations in the np -> d pi^0 reaction
The transverse spin correlations Axx and Ayy in the np-> d pi^0 reaction have
been measured for the first time in quasi-free kinematics at the COSY-ANKE
facility using a polarised deuteron beam incident on a polarised hydrogen cell
target. The results obtained for neutron energies close to 353 MeV and 600 MeV
are in good agreement with the partial wave analysis of data on the
isospin-related pp-> d pi^+ reaction, though the present results cover also the
small-angle region, which was largely absent from these data
Dynamic Behaviors of Mix-game Model and Its Applications
This paper proposes a modification to Minority Game (MG) by adding some
agents who play majority game into MG. So it is referred to as mix-game. The
highlight of this model is that the two groups of agents in mix-game have
different bounded abilities to deal with history information and to count their
own performance. Through simulations, this paper finds out that the local
volatilities change a lot by adding some agents who play majority game into MG,
and the change of local volatilities largely depends on different combinations
of history memories of the two groups. Furthermore this paper analyses the
underlying mechanisms for this finding. It also gives an example of
applications of mix-game.Comment: 22 pages, 11 figure, 1 table,revised versio
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