2,831 research outputs found
Homogeneous Polynomial Lyapunov Functions for Robust Local Synchronisation with Time-varying Uncertainties
This study studies robust local synchronisation in multi-agent systems with time-varying parametric uncertainties constrained in a polytope. In contrast to the existing methods with non-convex conditions via using quadratic Lyapunov function, a new criteria is proposed based on using homogeneous polynomial Lyapunov functions where the original system is suitably approximated by an uncertain polytopic system. Furthermore, the corresponding tractable conditions of linear matrix inequalities have been provided by exploiting the squares matrix representation. Then, the polytopic synchronisation margin problem is, for the first time, proposed and investigated via handling generalised eigenvalue problems. Lastly, numerical examples illustrate the usefulness of the proposed method.postprin
White Paper: Measuring the Neutrino Mass Hierarchy
This white paper is a condensation of a report by a committee appointed
jointly by the Nuclear Science and Physics Divisions at Lawrence Berkeley
National Laboratory (LBNL). The goal of this study was to identify the most
promising technique(s) for resolving the neutrino mass hierarchy. For the most
part, we have relied on calculations and simulations presented by the
proponents of the various experiments. We have included evaluations of the
opportunities and challenges for these experiments based on what is available
already in the literature.Comment: White paper prepared for Snowmass-201
Selection of fusion levels using the fulcrum bending radiograph for the management of adolescent idiopathic scoliosis patients with alternate level pedicle screw strategy: clinical decision-making and outcomes
Objective Selecting fusion levels based on the Luk et al criteria for operative management of thoracic adolescent idiopathic scoliosis (AIS) with hook and hybrid systems yields acceptable curve correction and balance parameters; however, it is unknown whether utilizing a purely pedicle screw strategy is effective. Utilizing the fulcrum bending radiographic (FBR) to assess curve flexibility to select fusion levels, the following study assessed the efficacy of pedicle screw fixation with alternate level screw strategy (ALSS) for thoracic AIS. Methods A retrospective study with prospective radiographic data collection/analyses (preoperative, postoperative 1-week and minimum 2-year follow-up) of 28 operative thoracic AIS patients undergoing ALSS was performed. Standing coronal/sagittal and FBR Cobb angles, FBR flexibility, fulcrum bending correction index (FBCI), trunkal shift, radiographic shoulder height (RSH), and list were assessed on x-rays. Fusion level selection was based on the Luk et al criteria and compared to conventional techniques. Results In the primary curve, the mean preoperative and postoperative 1 week and last follow-up standing coronal Cobb angles were 59.9, 17.2 and 20.0 degrees, respectively. Eighteen patients (64.3%) had distal levels saved (mean: 1.6 levels) in comparison to conventional techniques. Mean immediate and last follow-up FBCIs were 122.6% and 115.0%, respectively. Sagittal alignment did not statistically differ between any assessment intervals (p>0.05). A decrease in trunkal shift was noted from preoperative to last follow-up (p = 0.003). No statistically significant difference from preoperative to last follow-up was noted in RSH and list (p>0.05). No "add-on" of other vertebra or decompensation was noted and all patients achieved fusion. Conclusions This is the first report to note that using the FBR for decision-making in selecting fusion levels in thoracic AIS patients undergoing management with pedicle screw constructs (e.g. ALSS) is a cost-effective strategy that can achieve clinically-relevant deformity correction that is maintained and without compromising fusion levels.published_or_final_versio
Do contiguous multilevel pedicle screws offer added curve correction over alternate level screw strategy in AIS patients when curve flexibility is taken into account?
Concurrent Session 5A: Adolescent Idiopathic Scoliosis & Complications. Paper no. 97postprintThe 17th International Meeting on Advanced Spine Techniques (IMAST 2010), Toronto, Canada, 21-24 July 2010
Interleukin 23 promotes hepatocellular carcinoma metastasis via NF-kappa B induced matrix metalloproteinase 9 expression
published_or_final_versio
Selection of fusion levels using the fulcrum bending radiograph for the management of adolescent idiopathic scoliosis patients with alternate level pedicle screw strategy: clinical decision-making and outcomes
Objective Selecting fusion levels based on the Luk et al criteria for operative management of thoracic adolescent idiopathic scoliosis (AIS) with hook and hybrid systems yields acceptable curve correction and balance parameters; however, it is unknown whether utilizing a purely pedicle screw strategy is effective. Utilizing the fulcrum bending radiographic (FBR) to assess curve flexibility to select fusion levels, the following study assessed the efficacy of pedicle screw fixation with alternate level screw strategy (ALSS) for thoracic AIS. Methods A retrospective study with prospective radiographic data collection/analyses (preoperative, postoperative 1-week and minimum 2-year follow-up) of 28 operative thoracic AIS patients undergoing ALSS was performed. Standing coronal/sagittal and FBR Cobb angles, FBR flexibility, fulcrum bending correction index (FBCI), trunkal shift, radiographic shoulder height (RSH), and list were assessed on x-rays. Fusion level selection was based on the Luk et al criteria and compared to conventional techniques. Results In the primary curve, the mean preoperative and postoperative 1 week and last follow-up standing coronal Cobb angles were 59.9, 17.2 and 20.0 degrees, respectively. Eighteen patients (64.3%) had distal levels saved (mean: 1.6 levels) in comparison to conventional techniques. Mean immediate and last follow-up FBCIs were 122.6% and 115.0%, respectively. Sagittal alignment did not statistically differ between any assessment intervals (p>0.05). A decrease in trunkal shift was noted from preoperative to last follow-up (p = 0.003). No statistically significant difference from preoperative to last follow-up was noted in RSH and list (p>0.05). No "add-on" of other vertebra or decompensation was noted and all patients achieved fusion. Conclusions This is the first report to note that using the FBR for decision-making in selecting fusion levels in thoracic AIS patients undergoing management with pedicle screw constructs (e.g. ALSS) is a cost-effective strategy that can achieve clinically-relevant deformity correction that is maintained and without compromising fusion levels.published_or_final_versio
Oscillator model for dissipative QED in an inhomogeneous dielectric
The Ullersma model for the damped harmonic oscillator is coupled to the
quantised electromagnetic field. All material parameters and interaction
strengths are allowed to depend on position. The ensuing Hamiltonian is
expressed in terms of canonical fields, and diagonalised by performing a
normal-mode expansion. The commutation relations of the diagonalising operators
are in agreement with the canonical commutation relations. For the proof we
replace all sums of normal modes by complex integrals with the help of the
residue theorem. The same technique helps us to explicitly calculate the
quantum evolution of all canonical and electromagnetic fields. We identify the
dielectric constant and the Green function of the wave equation for the
electric field. Both functions are meromorphic in the complex frequency plane.
The solution of the extended Ullersma model is in keeping with well-known
phenomenological rules for setting up quantum electrodynamics in an absorptive
and spatially inhomogeneous dielectric. To establish this fundamental
justification, we subject the reservoir of independent harmonic oscillators to
a continuum limit. The resonant frequencies of the reservoir are smeared out
over the real axis. Consequently, the poles of both the dielectric constant and
the Green function unite to form a branch cut. Performing an analytic
continuation beyond this branch cut, we find that the long-time behaviour of
the quantised electric field is completely determined by the sources of the
reservoir. Through a Riemann-Lebesgue argument we demonstrate that the field
itself tends to zero, whereas its quantum fluctuations stay alive. We argue
that the last feature may have important consequences for application of
entanglement and related processes in quantum devices.Comment: 24 pages, 1 figur
Irradiation of benzene molecules by ion-induced and light-induced intense fields
Benzene, with its sea of delocalized -electrons in the valence orbitals,
is identified as an example of a class of molecules that enable establishment
of the correspondence between intense ion-induced and laser-light-induced
fields in experiments that probe ionization dynamics in temporal regimes
spanning the attosecond and picosecond ranges.Comment: 4 ps figure
Stability and Instability of Extreme Reissner-Nordstr\"om Black Hole Spacetimes for Linear Scalar Perturbations I
We study the problem of stability and instability of extreme
Reissner-Nordstrom spacetimes for linear scalar perturbations. Specifically, we
consider solutions to the linear wave equation on a suitable globally
hyperbolic subset of such a spacetime, arising from regular initial data
prescribed on a Cauchy hypersurface crossing the future event horizon. We
obtain boundedness, decay and non-decay results. Our estimates hold up to and
including the horizon. The fundamental new aspect of this problem is the
degeneracy of the redshift on the event horizon. Several new analytical
features of degenerate horizons are also presented.Comment: 37 pages, 11 figures; published version of results contained in the
first part of arXiv:1006.0283, various new results adde
Search for Direct CP Violation in Non-Leptonic Decays of Charged and Hyperons
A search for direct CP violation in the non-leptonic decays of hyperons has
been performed. In comparing the product of the decay parameters,
, in terms of an asymmetry parameter,
, between hyperons and anti-hyperons in the charged and decay sequence, we found no evidence of
direct CP violations. The parameter was measured to be .Comment: Submitted for publication; RevTex, 13 pages, 4 figure
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