oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 2 )

2019 ( 89 )

2018 ( 97 )

2017 ( 112 )

Custom range...

Search Results: 1 - 10 of 53051 matches for " David Lunardini "
All listed articles are free for downloading (OA Articles)
Page 1 /53051
Display every page Item
Operative Treatment of Cervical Myelopathy: Cervical Laminoplasty
Brett A. Braly,David Lunardini,Chris Cornett,William F. Donaldson
Advances in Orthopedics , 2012, DOI: 10.1155/2012/508534
Abstract: Cervical spondylotic myelopathy (CSM) is a degenerative process which may result in clinical signs and symptoms which require surgical intervention. Many treatment options have been proposed with various degrees of technical difficulty and technique sensitive benefits. We review laminoplasty as a motion-sparing posterior decompressive method. Current literature supports the use of laminoplasty for indicated decompression. We also decribe our surgical technique for an open-door, or “hinged”, laminoplasty.
Operative Treatment of Cervical Myelopathy: Cervical Laminoplasty
Brett A. Braly,David Lunardini,Chris Cornett,William F. Donaldson
Advances in Orthopedics , 2012, DOI: 10.1155/2012/508534
Abstract: Cervical spondylotic myelopathy (CSM) is a degenerative process which may result in clinical signs and symptoms which require surgical intervention. Many treatment options have been proposed with various degrees of technical difficulty and technique sensitive benefits. We review laminoplasty as a motion-sparing posterior decompressive method. Current literature supports the use of laminoplasty for indicated decompression. We also decribe our surgical technique for an open-door, or “hinged”, laminoplasty. 1. Introduction Cervical spondylotic myelopathy (CSM) is the natural result of degenerative compression on the cervical spinal cord. The result may be a progressive and stepwise deterioration of neurological function in patients. The chronic debilitating nature of this process justifies surgical decompression. Posterior decompression has been described as a treatment for CSM since the 1940s. Laminectomy was the initial surgical option used. The decompression was performed by rongeurs. However, the insertion of the rongeur in an already limited space available for the cord led often to a decrease in neurological function postoperatively [1–3]. Even with modern approaches to laminectomy using high speed burs, development of postoperative instability has led surgeons to explore more efficacious ways of decompression. In 1977, Hirabayashi and Satomi published their results on multisegment decompression by means of an open-door laminoplasty [4]. This technique allows for adequate posterior decompression of the spinal cord while retaining the posterior elements. This avoids the postoperative instability seen with laminectomy as well as the stiffness and risks of posterior cervical fusion. Additionally, motion is spared due to the absence of a fusion. There have since been multiple techniques for performing a cervical laminoplasty described with supporting literature [4–8]. These techniques include the expansive “open door,” a midline “French Door,” En Bloc resection, spinous process splitting, and Z-Plasty [4, 9]. Outcome studies have supported laminoplasty as a valid treatment for CSM however, no definitive literature shows its superiority to laminectomy in conjunction with a posterior cervical fusion. All surgical strategies appear to be equal in yielding neurologic outcomes, though differences are found in complication reports. Patient selection is crucial prior to proceeding with cervical laminoplasty. Special attention must be paid to sagittal alignment for optimal outcomes. Laminoplasty is ideal for multilevel stenosis (AP canal diameter < 13?mm) due to
Diffuse neutrino flux from failed supernovae
Cecilia Lunardini
Physics , 2009, DOI: 10.1103/PhysRevLett.102.231101
Abstract: I study the diffuse flux of electron antineutrinos from stellar collapses with direct black hole formation (failed supernovae). This flux is more energetic than that from successful supernovae, and therefore it might contribute substantially to the total diffuse flux above realistic detection thresholds. The total flux might be considerably higher than previously thought, and approach the sensitivity of SuperKamiokande. For more conservative values of the parameters, the flux from failed supernovae dominates for antineutrino energies above 30-45 MeV, with potential to give an observable spectral distortion at Megaton detectors.
Diffuse supernova neutrinos at underground laboratories
Cecilia Lunardini
Physics , 2010,
Abstract: I review the physics of the Diffuse Supernova Neutrino flux (or Background, DSNB), in the context of future searches at the next generation of neutrino telescopes. The theory of the DSNB is discussed in its fundamental elements, namely the cosmological rate of supernovae, neutrino production inside a core collapse supernova, redshift, and flavor oscillation effects. The current upper limits are also reviewed, and results are shown for the rates and energy distributions of the events expected at future 0.1- 1 Mt mass detectors using water, liquid argon and liquid scintillator. Perspectives are given on the significance of future observations of the DSNB, both at the discovery and precision phases, for the investigation of the physics of supernovae, and of the properties of the neutrino.
The diffuse neutrino flux from supernovae: upper limit on the electron neutrino component from the non-observation of antineutrinos at SuperKamiokande
Cecilia Lunardini
Physics , 2006, DOI: 10.1103/PhysRevD.73.083009
Abstract: I derive an upper bound on the electron neutrino component of the diffuse supernova neutrino flux from the constraint on the antineutrino component at SuperKamiokande. The connection between antineutrino and neutrino channels is due to the similarity of the muon and tau neutrino and antineutrino fluxes produced in a supernova, and to the conversion of these species into electron neutrinos and antineutrinos inside the star. The limit on the electron neutrino flux is 5.5 cm^-2 s^-1 above 19.3 MeV of neutrino energy, and is stronger than the direct limit from Mont Blanc by three orders of magnitude. It represents the minimal sensitivity required at future direct searches, and is intriguingly close to the reach of the Sudbury Neutrino Observatory (SNO) and of the ICARUS experiment. The electron neutrino flux will have a lower bound if the electron antineutrino flux is measured. Indicatively, the first can be smaller than the second at most by a factor of 2-3 depending on the details of the neutrino spectra at production.
Diffuse supernova neutrinos: oscillation effects, stellar cooling and progenitor mass dependence
Cecilia Lunardini,Irene Tamborra
Physics , 2012, DOI: 10.1088/1475-7516/2012/07/012
Abstract: We estimate the diffuse supernova neutrino background (DSNB) using the recent progenitor-dependent, long-term supernova simulations from the Basel group and including neutrino oscillations at several post-bounce times. Assuming multi-angle matter suppression of collective effects during the accretion phase, we find that oscillation effects are dominated by the matter-driven MSW resonances, while neutrino-neutrino collective effects contribute at the 5-10% level. The impact of the neutrino mass hierarchy, of the time-dependent neutrino spectra and of the diverse progenitor star population is 10% or less, small compared to the uncertainty of at least 25% of the normalization of the supernova rate. Therefore, assuming that the sign of the neutrino mass hierarchy will be determined within the next decade, the future detection of the DSNB will deliver approximate information on the MSW-oscillated neutrino spectra. With a reliable model for neutrino emission, its detection will be a powerful instrument to provide complementary information on the star formation rate and for learning about stellar physics.
Two modes of searching for new neutrino interactions at MINOS
Alexander Friedland,Cecilia Lunardini
Physics , 2006, DOI: 10.1103/PhysRevD.74.033012
Abstract: The SuperKamiokande atmospheric neutrino measurements leave substantial room for nonstandard interactions (NSI) of neutrinos with matter in the nu_e- nu_tau sector. Large values of the NSI couplings are accommodated if the vacuum oscillation parameters are changed from their standard values. Short and medium baseline neutrino beams can break this degeneracy by measuring the true vacuum oscillation parameters with the muon neutrino disappearance mode, for which the matter effects are negligible or subdominant. These experiments can also search for the nu_e-nu_tau flavor changing effects directly, by looking for nu_mu->nu_e conversion caused by the intervening matter. We discuss both of these methods for the case of MINOS. We find that, while the present MINOS data on nu_mu disappearance induce only minor changes on the constraints on the NSI parameters, the situation will improve markedly with the planned increase of the statistics by an order of magnitude. In that case, the precision will be enough to distinguish certain presently allowed NSI scenarios from the no-NSI case. NSI per quark of about 10% the size of the standard weak interaction could give a nu_mu - nu_e conversion probability of the order ~ 10^{-2}, measurable by MINOS in the same high statistics scenario. In this nu_mu - nu_e channel, the small effects of NSI could be comparable or larger than the vacuum contribution of the small angle theta_{13}. The expected theta_{13} bound at MINOS should be more properly interpreted as a bound in the theta_{13}-NSI parameter space.
Revealing local failed supernovae with neutrino telescopes
Lili Yang,Cecilia Lunardini
Physics , 2011, DOI: 10.1103/PhysRevD.84.063002
Abstract: We study the detectability of neutrino bursts from nearby direct black hole-forming collapses (failed supernovae) at Megaton detectors. Due to their high energetics, these bursts could be identified - by the time coincidence of N >= 2 or N >= 3 events within a ~ 1 s time window - from as far as ~ 4-5 Mpc away. This distance encloses several supernova-rich galaxies, so that failed supernova bursts could be detected at a rate of up to one per decade, comparable to the expected rate of the more common, but less energetic, neutron star-forming collapses. Thus, the detection of a failed supernova within the lifetime of a Mt detector is realistic. It might give the first evidence of direct black hole formation, with important implications on the physics of this phenomenon.
Cosmic Strings as Emitters of Extremely High Energy Neutrinos
Cecilia Lunardini,Eray Sabancilar
Physics , 2012, DOI: 10.1103/PhysRevD.86.085008
Abstract: We study massive particle radiation from cosmic string kinks, and its observability in extremely high energy neutrinos. In particular, we consider the emission of moduli --- weakly coupled scalar particles predicted in supersymmetric theories --- from the kinks of cosmic string loops. Since kinks move at the speed of light on strings, moduli are emitted with large Lorentz factors, and eventually decay into many pions and neutrinos via hadronic cascades. The produced neutrino flux has energy $E \gtrsim 10^{11} \rm{GeV}$, and is affected by oscillations and absorption (resonant and non-resonant). It is observable at upcoming neutrino telescopes such as JEM-EUSO, and the radio telescopes LOFAR and SKA, for a range of values of the string tension, and of the mass and coupling constant of the moduli.
A Mathematica script for harmonic oscillator nuclear matrix elements arising in semileptonic electroweak interactions
Wick Haxton,Cecilia Lunardini
Physics , 2007, DOI: 10.1016/j.cpc.2008.02.018
Abstract: Semi-leptonic electroweak interactions in nuclei - such as \beta decay, \mu capture, charged- and neutral-current neutrino reactions, and electron scattering - are described by a set of multipole operators carrying definite parity and angular momentum, obtained by projection from the underlying nuclear charge and three-current operators. If these nuclear operators are approximated by their one-body forms and expanded in the nucleon velocity through order |\vec{p}|/M, where \vec{p} and M are the nucleon momentum and mass, a set of seven multipole operators is obtained. Nuclear structure calculations are often performed in a basis of Slater determinants formed from harmonic oscillator orbitals, a choice that allows translational invariance to be preserved. Harmonic-oscillator single-particle matrix elements of the multipole operators can be evaluated analytically and expressed in terms of finite polynomials in q^2, where q is the magnitude of the three-momentum transfer. While results for such matrix elements are available in tabular form, with certain restriction on quantum numbers, the task of determining the analytic form of a response function can still be quite tedious, requiring the folding of the tabulated matrix elements with the nuclear density matrix, and subsequent algebra to evaluate products of operators. Here we provide a Mathematica script for generating these matrix elements, which will allow users to carry out all such calculations by symbolic manipulation. This will eliminate the errors that may accompany hand calculations and speed the calculation of electroweak nuclear cross sections and rates. We illustrate the use of the new script by calculating the cross sections for charged- and neutral-current neutrino scattering in ^{12}C.
Page 1 /53051
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.