5,699 research outputs found
Stability of five-dimensional rotating black holes projected on the brane
We study the stability of five-dimensional Myers-Perry black holes with a
single angular momentum under linear perturbations, and we compute the
quasinormal modes (QNM's) of the black hole metric projected on the brane,
using Leaver's continued fraction method. In our numerical search we do not
find unstable modes. The damping time of modes having l=m=2 and l=m=1 tends to
infinity as the black hole spin tends to the extremal value, showing a
behaviour reminiscent of the one observed for ordinary 4-dimensional Kerr black
holes.Comment: 8 pages, 2 figures. Updated to match the version published on PRD.
Corrected a small typo (which does not affect the results) in equation (6) of
the published pape
Aligned spin neutron star-black hole mergers: a gravitational waveform amplitude model
The gravitational radiation emitted during the merger of a black hole with a
neutron star is rather similar to the radiation from the merger of two black
holes when the neutron star is not tidally disrupted. When tidal disruption
occurs, gravitational waveforms can be broadly classified in two groups,
depending on the spatial extent of the disrupted material. Extending previous
work by some of us, here we present a phenomenological model for the
gravitational waveform amplitude in the frequency domain encompassing the three
possible outcomes of the merger: no tidal disruption, "mild" and "strong" tidal
disruption. The model is calibrated to 134 general-relativistic numerical
simulations of binaries where the black hole spin is either aligned or
antialigned with the orbital angular momentum. All simulations were produced
using the SACRA code and piecewise polytropic neutron star equations of state.
The present model can be used to determine when black-hole binary waveforms are
sufficient for gravitational-wave detection, to extract information on the
equation of state from future gravitational-wave observations, to obtain more
accurate estimates of black hole-neutron star merger event rates, and to
determine the conditions under which these systems are plausible candidates as
central engines of gamma-ray bursts, macronovae and kilonovae.Comment: 15 pages, 7 figures, 1 tabl
Quality of Life and Subjective Outcomes Following Maxillomandibular Advancement Surgery for the Treatment of Obstructive Sleep Apnea
Objective: The aim of this study was to assess outcomes related to general quality of life, daytime sleepiness and functional sleep outcomes, functional outcomes of orthognathic surgery, and facial aesthetics in patients undergoing maxillomandibular advancement (MMA) surgery for the treatment of obstructive sleep apnea (OSA).
Materials and Methods: This was a cross-sectional self-report study. A questionnaire was constructed using questions drawn from previously validated questionnaires. The survey was distributed to 25 patients who underwent MMA surgery for the treatment of OSA at LHSC in London, Ontario by a single surgeon between 2002 and 2013.
Results: The survey results showed that MMA patients responded positively with respect to quality of life, snoring, functional sleep outcomes and daytime sleepiness, and facial aesthetics. Nineteen (86.4%) indicated that their sleep apnea symptoms have improved since the surgery. Eighteen (81.8%) reported neutral or positive changes with respect to facial attractiveness. Nineteen (86.4%) indicated that their overall quality of life has become better since having MMA. Most patients indicated that the surgery was worthwhile and would recommend it to others suffering from OSA.
Conclusions: MMA surgery for the treatment of OSA appears to have an overall positive effect on quality of life, sleep outcomes, and aesthetic outcomes. The majority of patients found the surgery worthwhile. Orthodontic treatment in conjunction with MMA appears to enhance the subjective aesthetic outcomes of treatment
A first unbiased global determination of polarized PDFs and their uncertainties
We present a first global determination of spin-dependent parton distribution
functions (PDFs) and their uncertainties using the NNPDF methodology:
NNPDFpol1.1. Longitudinally polarized deep-inelastic scattering data, already
used for the previous NNPDFpol1.0 PDF set, are supplemented with the most
recent polarized hadron collider data for inclusive jet and boson
production from the STAR and PHENIX experiments at RHIC, and with open-charm
production data from the COMPASS experiment, thereby allowing for a separate
determination of the polarized quark and anti-quark PDFs, and an improved
determination of the medium- and large- polarized gluon PDF. We study the
phenomenological implications of the NNPDFpol1.1 set, and we provide
predictions for the longitudinal double-spin asymmetry for semi-inclusive pion
production at RHIC.Comment: 36 pages, 16 figures. Final version to be published in Nucl. Phys. B.
Small textual improvements and minor typos correcte
Fermat, Leibniz, Euler, and the gang: The true history of the concepts of limit and shadow
Fermat, Leibniz, Euler, and Cauchy all used one or another form of
approximate equality, or the idea of discarding "negligible" terms, so as to
obtain a correct analytic answer. Their inferential moves find suitable proxies
in the context of modern theories of infinitesimals, and specifically the
concept of shadow. We give an application to decreasing rearrangements of real
functions.Comment: 35 pages, 2 figures, to appear in Notices of the American
Mathematical Society 61 (2014), no.
Co-digestion of macroalgae for biogas production: an LCA-based environmental evaluation
Algae represent a favourable and potentially sustainable source of biomass for bioenergy-based industrial pathways in the future.
The study, performed on a real pilot plant implemented in Augusta (Italy) within the frame of the BioWALK4Biofuels project,
aims to figure out whether seaweed (macroalgae) cultivated in near-shore open ponds could be considered a beneficial aspect as a
source of biomass for biogas production within the co-digestion with local agricultural biological waste. The LCA results
confirm that the analysed A and B scenarios (namely the algae-based co-digestion scenario and agricultural mix feedstock
scenario) present an environmental performance more favourable than that achieved with conventional non-renewable-based
technologies (specifically natural gas - Scenario C). Results show that the use of seaweed (Scenario A) represent a feasible
solution in order to replace classical biomass used for biofuel production from a land-based feedstock. The improvement of the
environmental performances is quantifiable on 10% respect to Scenario B, and 38 times higher than Scenario
Weak Equivalence Principle Test on a Sounding Rocket
SR-POEM, our principle of equivalence measurement on a sounding rocket, will
compare the free fall rate of two substances yielding an uncertainty of E-16 in
the estimate of \eta. During the past two years, the design concept has matured
and we have been working on the required technology, including a laser gauge
that is self aligning and able to reach 0.1 pm per root hertz for periods up to
40 s. We describe the status and plans for this project.Comment: Presented at the Fifth Meeting on CPT and Lorentz Symmetry,
Bloomington, Indiana, June 28-July 2, 201
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