1,432 research outputs found

    Factorization and resummation: A new paradigm to improve gravitational wave amplitudes. II: the higher multipolar modes

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    The factorization and resummation approach of Nagar and Shah~[Phys.~Rev.~D~94 (2016), 104017], designed to improve the strong-field behavior of the post-Newtonian (PN) residual waveform amplitudes fmf_{\ell m}'s entering the effective-one-body, circularized, gravitational waveform for spinning coalescing binaries, is here improved and generalized to all multipoles up to =6\ell=6. For a test-particle orbiting a Kerr black hole, each multipolar amplitude is truncated at relative 6~post Newtonian (PN) order, both for the orbital (nonspinning) and spin factors. By taking a certain Pad\'e approximant (typically the P24P^4_2 one) of the orbital factor in conjuction with the inverse Taylor (iResum) representation of the spin factor, it is possible to push the analytical/numerical agreement of the energy fluxe at the level of 5%5\% at the last-stable-orbit for a quasi-maximally spinning black hole with dimensionless spin parameter +0.99+0.99. When the procedure is generalized to comparable-mass binaries, each orbital factor is kept at relative 3+33^{+3}PN order, i.e. the 3PN comparable-mass terms are hybridized with higher PN test-particle terms up to 6PN relative order. The same Pad\'e resummation is used for continuity. By contrast, the spin factor is only kept at the highest comparable-mass PN-order currently available. We illustrate that the consistency between different truncations in the spin content of the waveform amplitudes is stronger in the resummed case than when using the standard Taylor-expanded form of Pan et al.~[Phys.~Rev.~D~83 (2011) 064003]. We finally introduce a method to consistently hybridize comparable-mass and test-particle information {\it also} in the presence of spin (including the spin of the particle), discussing it explicitly for the =m=2\ell=m=2 spin-orbit and spin-square terms.Comment: 22 pages, 5 figures, submitted to Phys. Rev.

    Quasi-5.5PN TaylorF2 approximant for compact binaries: point-mass phasing and impact on the tidal polarizability inference

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    We derive a point-mass (nonspinning) frequency-domain TaylorF2 phasing approximant at quasi-5.5 post-Newtonian (PN) accuracy for the gravitational wave from coalescing compact binaries. The new approximant is obtained by Taylor-expanding the effective-one-body (EOB) resummed energy and and angular momentum flux along circular orbits with all the known test-particle information up to 5.5PN. The -- yet uncalculated -- terms at 4PN order and beyond entering both the energy flux and the energy are taken into account as free parameters and then set to zero. We compare the quasi-5.5PN and 3.5PN approximants against full EOB waveforms using gauge-invariant phasing diagnostics Qω=ω^2/ω^˙Q_\omega=\hat\omega^2/\dot{\hat\omega}, where ω^\hat\omega is the dimensionless gravitational-wave frequency. The quasi-5.5PN phasing is found to be systematically closer to the EOB one than the 3.5PN one. Notably, the quasi-5.5PN (3.5PN) approximant accumulates a EOB-PN dephasing of ΔΨEOBPN103\Delta\Psi^{\rm EOBPN}\sim10^{-3}rad (0.130.13rad) up to frequency ω^0.06\hat\omega \simeq 0.06, 6 orbits to merger, (ω^0.086\hat\omega \simeq 0.086, 2 orbits to merger) for a fiducial binary neutron star system. We explore the performance of the quasi-5.5PN approximant on the measurement of the tidal polarizability parameter Λ~\tilde\Lambda using injections of EOB waveforms hybridized with numerical relativity merger waveforms. We prove that the quasi-5.5PN point-mass approximant augmented with 6PN-accurate tidal terms allows one to reduce (and in many cases even eliminate) the biases in the measurement of Λ~\tilde\Lambda that are instead found when the standard 3.5PN point-mass baseline is used. Methodologically, we demonstrate that the combined use of QωQ_\omega analysis and of the Bayesian parameter estimation offers a new tool to investigate the impact of systematics on gravitational-wave inference.Comment: 13 pages, 7 figures, submitted to Phys. Rev.

    Orofacial muscles activity in children with swallowing dysfunction and removable functional appliances

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    Swallowing dysfunction is a frequent disorder among children and refers to an altered tongue posture and abnormal tongue movement during swallowing. Removable functional appliance is one of the treatments applied by dentistry to correct this disorder. The aim of this study was to evaluate any differences on orofacial muscles activity in children with swallowing dysfunction with and without removable functional appliances. 68 children were eligible for the study and divided into the orthodontic group (OG) and the no-orthodontic group (NO-OG). Both groups performed a dental occlusion-class evaluation, a swallowing function test and a myoscan analysis in order to measure perioral forces (i.e. tongue extension force, lip pressure, masseter contraction force). Our results showed a significant difference (P=0.02) between OG and NO-OG for the tongue extension force, whereas no significant differences (P>0.05) were found for the other parameters. Our findings suggest that children with swallowing dysfunction and removable functional appliance show orofacial muscles activity within the range of reference values (except for the lip pressure). However, we hypothesize that orthodontic treatment can achieve more effective results with integration of myofunctional therapy

    Posterior corneal surface stability after femtosecond laser-assisted keratomileusis

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    The purpose of this study was to evaluate posterior corneal surface variation after femtosecond laser-assisted keratomileusis in patients with myopia and myopic astigmatism. Patients were evaluated by corneal tomography preoperatively and at 1, 6, and 12 months. We analyzed changes in the posterior corneal curvature, posterior corneal elevation, and anterior chamber depth. Moreover, we explored correlation between corneal ablation depth, residual corneal thickness, percentage of ablated corneal tissue, and preoperative corneal thickness. During follow-up, the posterior corneal surface did not have a significant forward corneal shift: no significant linear relationships emerged between the anterior displacement of the posterior corneal surface and corneal ablation depth, residual corneal thickness, or percentage of ablated corneal tissue

    Do You Remember Mitochondria?

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    A giant retroperitoneal hemangiosarcoma in a young boy: CT findings

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    Retroperitoneal hemangiosarcoma (RH) is an uncommon neoplasm that derives from the vascular endothelium; due to its biological behavior, it should be distinguished from other retroperitoneal tumors. We report a case of a 40-year-old man with diagnosis of retroperitoneal mass, that was suspected to be malignant. The specimen was histopathologically proved to be a hemangiosarcoma. The patient was suffering from left upper quadrants prolonged abdominal pain, and had made a contrast-enhanced abdominal Computed Tomography (CT) that had shown the voluminous abdominal mass

    Recycling of Pre-Washed Municipal Solid Waste Incinerator Fly Ash in the Manufacturing of Low Temperature Setting Geopolymer Materials

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    In this work, three samples of municipal solid waste incinerators fly ash (MSWI-FA) have been stabilized in systems containing coal fly ash to create geopolymers through a polycondensation reaction. Monolithic products have been obtained with both MSWI fly ash as received and after the partial removal of chloride and sulfate by water washing. The polycondensation products have been characterized qualitatively by means of Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy and quantitatively, through the determination of the volume of reacted water and silicate. Furthermore, the heavy metals and chloride releases together with the physico-mechanical properties have been evaluated on the hardened products. In conclusion, considering the technological and environmental performances of the obtained geopolymers, they could be suitable for many non-structural applications, such as backfilling of abandoned quarries, decorative materials or brick fireplaces, hearths, patios, etc

    Prvi podaci o staništu, prehrani i dužinsko-masenom odnosu vrste Gobius incognitus Kovačić & Šanda, 2016 (Pisces: Gobiidae)

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    In this work, we present first data on biological and ecological aspects of Gobius incognitus from specimens from the Ionian Sea (central Mediterranean Sea). In particular, we provided first data on habitat preference, diet and length-weight relationship of G. incognitus on material with confirmed species identity. The species preferred “mixed bottom” (sand and rocks), where it reached relatively high abundances. The diet analysis showed that G. incognitus is a generalist and opportunistic feeder. However, small benthic crustaceans were the most important prey group. The mean total length of specimens was 6.72 ± 1.85 cm and the growth was positive allometric.U ovom radu iznose se prvi podatci o biološkim i ekološkim značajkama vrste Gobius incognitus na temelju uzoraka iz Jonskog mora (središnji dio Sredozemnog mora). Posebno se ističu podatci o staništu, prehrani i dužnsko - masenom odnosu. Vrsta Gobius incognituspreferirala je „miješano dno“ (pijesak i stijene), gdje je dostigla relativno veliku brojnost. Analiza prehrane pokazala je da G. incognitus slijedi oportunistički način prehrane. Međutim, mali bentoski rakovi bili su najvažniji plijen. Srednja ukupna dužina iznosila je 6,72 ± 1,85 cm, a rast je bio alometrijski pozitivan
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