29,811 research outputs found

    Precise LIGO Lensing Rate Predictions for Binary Black Holes

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    We show how LIGO is expected to detect coalescing binary black holes at z>1z>1, that are lensed by the intervening galaxy population. Gravitational magnification, Ī¼\mu, strengthens gravitational wave signals by Ī¼\sqrt{\mu}, without altering their frequencies, which if unrecognised leads to an underestimate of the event redshift and hence an overestimate of the binary mass. High magnifications can be reached for coalescing binaries because the region of intense gravitational wave emission during coalescence is so small (āˆ¼\sim100km), permitting very close projections between lensing caustics and gravitational-wave events. Our simulations incorporate accurate waveforms convolved with the LIGO power spectral density. Importantly, we include the detection dependence on sky position and orbital orientation, which for the LIGO configuration translates into a wide spread in observed redshifts and chirp masses. Currently we estimate a detectable rate of lensed events \rateEarly{}, that rises to \rateDesign{}, at LIGO's design sensitivity limit, depending on the high redshift rate of black hole coalescence.Comment: 5 pages, 4 figure

    Penicillium marneffei Infection in AIDS

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    Penicillium marneffei is a dimorphic fungus which is endemic in Southeast Asia. It is an opportunistic pathogen which has emerged to become an AIDS-defining illness in the endemic areas. Early diagnosis with prompt initiation of treatment is crucial for its management. Prompt diagnosis can often be established through careful cytological and histological examination of clinical specimens although microbiological culture remains the gold standard for its diagnosis. Standard antifungal treatment for AIDS patients with penicilliosis is well established. Highly active antiretroviral therapy should be started early together with the antifungal treatment. Special attention should be paid to potential drug interaction between antiretroviral and antifungal treatments. Secondary prophylaxis may be discontinued with a low risk of relapse of the infection once the immune dysfunction has improved

    Minimizing Unsatisfaction in Colourful Neighbourhoods

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    Colouring sparse graphs under various restrictions is a theoretical problem of significant practical relevance. Here we consider the problem of maximizing the number of different colours available at the nodes and their neighbourhoods, given a predetermined number of colours. In the analytical framework of a tree approximation, carried out at both zero and finite temperatures, solutions obtained by population dynamics give rise to estimates of the threshold connectivity for the incomplete to complete transition, which are consistent with those of existing algorithms. The nature of the transition as well as the validity of the tree approximation are investigated.Comment: 28 pages, 12 figures, substantially revised with additional explanatio

    Heavy Quarkonia and Quark Drip Lines in Quark-Gluon Plasma

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    Using the potential model and thermodynamical quantities obtained in lattice gauge calculations, we determine the spontaneous dissociation temperatures of color-singlet quarkonia and the `quark drip lines' which separate the region of bound QQĖ‰Q\bar Q states from the unbound region. The dissociation temperatures of J/ĻˆJ/\psi and Ļ‡b\chi_b in quenched QCD are found to be 1.62TcT_c and 1.18Tc1.18T_c respectively, in good agreement with spectral function analyses. The dissociation temperature of J/ĻˆJ/\psi in full QCD with 2 flavors is found to be 1.42TcT_c. For possible bound quarkonium states with light quarks, the characteristics of the quark drip lines severely limit the stable region close to the phase transition temperature. Bound color-singlet quarkonia with light quarks may exist very near the phase transition temperature if their effective quark mass is of the order of 300-400 MeV and higher.Comment: 8 pages, 2 figures, in LaTex, invited talk presented at the International Conference on Strangeness in Quark Matter, UCLA, March 26-31, 200

    Performance Analysis of AF Relaying With Selection Combining in Nakagami-m Fading

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    This paper investigates the performance analysis of a selection combining scheme, which utilizes a variable gain amplify and forward relay over a Nakagami-m fading channel. A selection combiner at a destination node chooses the better link between a relay channel and a direct channel. We derived exact closed-form expressions for moments of signal to noise ratio (SNR), ergodic capacity, and average symbol error probability. Simulation examples confirm that our exact formulas offer a more accurate analysis tool for selection combining than other prevailing approximations without extra complexity. The derived expressions serve as a useful tool for system design due to their validity for any SNR and arbitrary system parameters

    Interferometry signatures for QCD first-order phase transition in heavy ion collisions at GSI-FAIR energies

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    Using the technique of quantum transport of the interfering pair we examine the Hanbury-Brown-Twiss (HBT) interferometry signatures for the particle-emitting sources of pions and kaons produced in the heavy ion collisions at GSI-FAIR energies. The evolution of the sources is described by relativistic hydrodynamics with the system equation of state of the first-order phase transition from quark-gluon plasma (QGP) to hadronic matter. We use quantum probability amplitudes in a path-integral formalism to calculate the two-particle correlation functions, where the effects of particle decay and multiple scattering are taken into consideration. We find that the HBT radii of kaons are smaller than those of pions for the same initial conditions. Both the HBT radii of pions and kaons increase with the system initial energy density. The HBT lifetimes of the pion and kaon sources are sensitive to the initial energy density. They are significantly prolonged when the initial energy density is tuned to the phase boundary between the QGP and mixed phase. This prolongations of the HBT lifetimes of pions and kaons may likely be observed in the heavy ion collisions with an incident energy in the GSI-FAIR energy range.Comment: 16 pages, 4 figure

    Fluid Antenna System for 6G: When Bruce Lee Inspires Wireless Communications

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    Since its inception, multiple-input multiple-output (MIMO) has become a magical technology that continues to break new grounds and deliver the needed upgrades in mobile communications. The emerging 5G systems are also being labelled by many as the massive MIMO generation. This somewhat oversimplified view is perhaps a reflection of the great impact MIMO has had on our generation of mobile communication networks. Although the technologies have evolved in the past decades, the principle remains the sameā€“to exploit the diversity of different copies of signals at independent locations for reducing the degree of fading and randomness of wireless channels. Through signal processing and coding, the diversity has been translated successfully into capacity gain and enhancement in other forms of the quality-of-service. This article identifies ā€œfluidā€ antenna as a trending technology that may succeed MIMO and become a reality to transform wireless communications to a new height. Fluid antenna is a radical approach that advocates software-controlled position-flexible shape-flexible antenna. The concept liberates antennas to unleash massive diversity inherent in the small space of a mobile device and makes possible new opportunities that were previously unthinkable. This article attempts to be imaginative and aims to take readers on a short journey of what fluid antenna might bring in future-generation mobile communications systems and speculate on its impact
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