8,681 research outputs found
Mergers of binary stars: The ultimate heavy-ion experience
The mergers of black hole-neutron star binaries are calcuated using a
pseudo-general relativistic potential that incorporates post-Newtonian corrections. Both normal matter neutron stars and
self-bound strange quark matter stars are considered as black hole partners. As
long as the neutron stars are not too massive relative to the black hole mass,
orbital decay terminates in stable mass transfer rather than an actual merger.
For a normal neutron star, mass transfer results in a widening of the orbit but
the stable transfer ends before the minimum neutron star mass is reached. For a
strange star, mass transfer does not result in an appreciable enlargement of
the orbital separation, and the stable transfer continues until the strange
star essentially disappears. These differences might be observable through
their respective gravitational wave signatures.Comment: Contribution to QM04 proceedings. Submitted to Journal of Physics
Multi-aspect, robust, and memory exclusive guest os fingerprinting
Precise fingerprinting of an operating system (OS) is critical to many security and forensics applications in the cloud, such as virtual machine (VM) introspection, penetration testing, guest OS administration, kernel dump analysis, and memory forensics. The existing OS fingerprinting techniques primarily inspect network packets or CPU states, and they all fall short in precision and usability. As the physical memory of a VM always exists in all these applications, in this article, we present OS-Sommelier+, a multi-aspect, memory exclusive approach for precise and robust guest OS fingerprinting in the cloud. It works as follows: given a physical memory dump of a guest OS, OS-Sommelier+ first uses a code hash based approach from kernel code aspect to determine the guest OS version. If code hash approach fails, OS-Sommelier+ then uses a kernel data signature based approach from kernel data aspect to determine the version. We have implemented a prototype system, and tested it with a number of Linux kernels. Our evaluation results show that the code hash approach is faster but can only fingerprint the known kernels, and data signature approach complements the code signature approach and can fingerprint even unknown kernels
Method for Generating Long-Range Correlations for Large Systems
We propose a new method to generate a sequence of random numbers with
long-range power-law correlations that overcomes known difficulties associated
with large systems. The new method presents an improvement on the commonly-used
methods. We apply the algorithm to generate enhanced diffusion, isotropic and
anisotropic self-affine surfaces, and isotropic and anisotropic correlated
percolation.Comment: 4 pages, REVTEX, figures available upon request from
[email protected]
Unpolarized light in quantum optics
We present a new derivation of the unpolarized quantum states of light, whose
general form was first derived by Prakash and Chandra [Phys. Rev. A 4, 796
(1971)]. Our derivation makes use of some basic group theory, is
straightforward, and offers some new insights.Comment: 3 pages, REVTeX, presented at ICQO'200
Molecular Characterization of Wolbachia and its Phage WO in the Laboratory Populations of Drosophila
Wolbachia are a group of maternally inherited intracellular rickettsial á-proteobacteria, infecting wide range of arthropods and filarial nematodes. They infect around 66% of arthropods and impose various fitness related effects in their host populations to enhance their transmission. In the current study, four out of eight laboratory populations of Drosophila has been found positive for Wolbachia and its phage WO through PCR diagnostics. Four populations of D. ananassae were infected with wRiv strain of Wolbachia and its phage, while other four D. melanogaster populations do not have either of them. Further, phylogenetic characterization of Wolbachia and phage WO from D. ananassae indicates close relationship across other Drosophila species, suggesting possible horizontal transmissio
Exergy analysis of a high-temperature-steam-driven, varied-pressure, humidification–dehumidification system coupled with reverse osmosis
In this study, exergy analysis of a novel desalination system is presented and discussed. The water desalination is carried out using combined humidification–dehumidification and reverse osmosis technologies. Six system performance parameters are examined: overall exergetic efficiency, equivalent electricity consumption, specific exergy destruction, specific exergy lost, and total true specific exergy lost, as well as the exergy destruction ratios of the main components. The total true specific exergy lost is a new parameter presented in this study. It is a function of summation of total the exergy destruction rate and loss per total mass flow rate of the total pure water produced. This parameter is found to be a useful parameter to assess the exergetic performance of the system considered. By contrast, use of overall exergetic efficiency as an assessment tool can result in misleading conclusions for such a desalination system and, hence, is not recommended. Furthermore, this study reveals that the highest exergy destruction occurs in the thermal vapor compressor, which accounts for 50% of the total exergy destruction of the system considered. This study, in addition, demonstrates that the specific exergy destruction of the dehumidifier and TVC are the parameters that most strongly affect the performance of the system.Center for Clean Water and Clean Energy at MIT and KFUP
Rapid Cooling of the Neutron Star in Cassiopeia A Triggered by Neutron Superfluidity in Dense Matter
We propose that the observed cooling of the neutron star in Cassiopeia A is
due to enhanced neutrino emission from the recent onset of the breaking and
formation of neutron Cooper pairs in the 3P2 channel. We find that the critical
temperature for this superfluid transition is ~0.5x10^9 K. The observed
rapidity of the cooling implies that protons were already in a superconducting
state with a larger critical temperature. Our prediction that this cooling will
continue for several decades at the present rate can be tested by continuous
monitoring of this neutron star.Comment: Revised version, to be published in Phys. Rev. Let
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