1,136 research outputs found
Substitution induced pinning in MgB_2 superconductor doped with SiC nano-particles
By doping MgB_2 superconductor with SiC nano-particles, we have successfully
introduced pinning sites directly into the crystal lattice of MgB_2 grains
(intra-grain pinning). It became possible due to the combination of
counter-balanced Si and C co-substitution for B, leading to a large number of
intra-granular dislocations and the dispersed nano-size impurities induced by
the substitution. The magnetic field dependence of the critical current density
was significantly improved in a wide temperature range, whereas the transition
temperature in the sample MgB_2(SiC)_x having x = 0.34, the highest doping
level prepared, dropped only by 2.6 K.Comment: 4 pages, 6 figure
LOW ENERGY SUPERSYMMETRY PHENOMENOLOGY
We summarize the current status and future prospects for low energy (weak
scale) supersymmetry. In particular, we evaluate the capabilities of various
, and colliders to discover evidence for supersymmetric
particles. Furthermore, assuming supersymmetry is discovered, we discuss
capabilities of future facilities to dis-entangle the anticipated spectrum of
super-particles, and, via precision measurements, to test mass and coupling
parameters for comparison with various theoretical expectations. We comment
upon the complementarity of proposed hadron and machines for a
comprehensive study of low energy supersymmetry.Comment: 74 page (Latex) file; a PS or uuencoded manuscript with embedded
figures is available via anonymous ftp at
ftp://hep.fsu.edu/preprints/baer/FSUHEP950401.ps or .uu . Contributed chapter
to DPF study group on Electroweak Symmetry Breaking and Beyond the Standard
Model
Number phase uncertainty relations: verification by homodyning
It is shown that fundamental uncertainty relations between photon number and
canonical phase of a single-mode optical field can be verified by means of
balanced homodyne measurement. All the relevant quantities can be sampled
directly from the measured phase-dependent quadrature distribution.Comment: 1 Ps figure (divided in 3 subfigures) using REVTE
Calculation of wakefields in a 17 GHz beam-driven photonic band-gap accelerator structure
We present the theoretical analysis and computer simulation of the wakefields in a 17 GHz photonic band-gap (PBG) structure for accelerator applications. Using the commercial code CST Particle Studio, the fundamental accelerating mode and dipole modes are excited by passing an 18 MeV electron beam through a seven-cell traveling-wave PBG structure. The characteristics of the longitudinal and transverse wakefields, wake potential spectrum, dipole mode distribution, and their quality factors are calculated and analyzed theoretically. Unlike in conventional disk-loaded waveguide (DLW) structures, three dipole modes (TM[subscript 11]-like, TM[subscript 12]-like, and TM[subscript 13]-like) are excited in the PBG structure with comparable initial amplitudes. These modes are separated by less than 4 GHz in frequency and are damped quickly due to low radiative Q factors. Simulations verify that a PBG structure provides wakefield damping relative to a DLW structure. Simulations were done with both single-bunch excitation to determine the frequency spectrum of the wakefields and multibunch excitation to compare to wakefield measurements taken at MIT using a 17 GHz bunch train. These simulation results will guide the design of next-generation high-gradient accelerator PBG structures.United States. Dept. of Energy. High Energy Physics Division (Contract DEFG02- 91ER40648)China. Fundamental Research Funds for the Central Universities (Contract ZYGX 2010J055
Quantum homodyne tomography with a priori constraints
I present a novel algorithm for reconstructing the Wigner function from
homodyne statistics. The proposed method, based on maximum-likelihood
estimation, is capable of compensating for detection losses in a numerically
stable way.Comment: 4 pages, REVTeX, 2 figure
Bitwise Bell inequality violations for an entangled state involving 2N ions
Following on from previous work [J. A. Larsson, Phys. Rev. A 67, 022108
(2003)], Bell inequalities based on correlations between binary digits are
considered for a particular entangled state involving 2N trapped ions. These
inequalities involve applying displacement operations to half of the ions and
then measuring correlations between pairs of corresponding bits in the binary
representations of the number of centre-of-mass phonons of N particular ions.
It is shown that the state violates the inequalities and thus displays
nonclassical correlations. It is also demonstrated that it violates a Bell
inequality when the displacements are replaced by squeezing operations.Comment: 12 pages, 5 figures, accepted for publication in Phys. Rev.
Universal homodyne tomography with a single local oscillator
We propose a general method for measuring an arbitrary observable of a
multimode electromagnetic field using homodyne detection with a single local
oscillator. In this method the local oscillator scans over all possible linear
combinations of the modes. The case of two modes is analyzed in detail and the
feasibility of the measurement is studied on the basis of Monte-Carlo
simulations. We also provide an application of this method in tomographic
testing of the GHZ state.Comment: 12 pages, 5 figures (8 eps files
Implementation of a hospital-wide multidisciplinary blunt chest injury care bundle (ChIP): Fidelity of delivery evaluation
BackgroundIneffective intervention for patients with blunt chest wall injury results in high rates of morbidity and mortality. To address this, a blunt chest injury care bundle protocol (ChIP) was developed, and a multifaceted plan was implemented using the Behaviour Change Wheel.ObjectiveThe purpose of this study was to evaluate the reach, fidelity, and dose of the ChIP intervention to discern if it was activated and delivered to patients as intended at two regional Australian hospitals.MethodsThis is a pretest and post-test implementation evaluation study. The proportion of ChIP activations and adherence to ChIP components received by eligible patients were compared before and after intervention over a 4-year period. Sample medians were compared using the nonparametric median test, with 95% confidence intervals. Differences in proportions for categorical data were compared using the two-sample z-test.Results/findingsOver the 19-month postimplementation period, 97.1% (n = 440) of eligible patients received ChIP (reach). The median activation time was 134 min; there was no difference in time to activation between business hours and after-hours; time to activation was not associated with comorbidities and injury severity score. Compared with the preimplementation group, the postimplementation group were more likely to receive evidence-based treatments (dose), including high-flow nasal cannula use (odds ratio [OR] = 6.8 [95% confidence interval {CI} = 4.8-9.6]), incentive spirometry in the emergency department (OR = 7.5, [95% CI = 3.2-17.6]), regular analgesia (OR = 2.4 [95% CI = 1.5-3.8]), regional analgesia (OR = 2.8 [95% CI = 1.5-5.3]), patient-controlled analgesia (OR = 1.8 [95% CI = 1.3-2.4]), and multiple specialist team reviews, e.g., surgical review (OR = 9.9 [95% CI = 6.1-16.1]).ConclusionsHigh fidelity of delivery was achieved and sustained over 19 months for implementation of a complex intervention in the acute context through a robust implementation plan based on theoretical frameworks. There were significant and sustained improvements in care practices known to result in better patient outcomes. Findings from this evaluation can inform future implementation programs such as ChIP and other multidisciplinary interventions in an emergency or acute care context
Prospects for Supersymmetry at LEP2
Working within the framework of the minimal supergravity model with gauge
coupling unification and radiative electroweak symmetry breaking (SUGRA), we
map out regions of parameter space explorable by experiments at LEP2, for
center of mass energy options of , and 205 GeV. We
compute signals from all accessible SUSY pair production
processes using the ISAJET simulation program, and devise cuts that enhance the
signal relative to Standard Model backgrounds, and which also serve to
differentiate various supersymmetric processes from one another. We delineate
regions of SUGRA parameter space where production of neutralino pairs, chargino
pairs, slepton pairs and the production of the light Higgs scalar of SUSY is
detectable above Standard Model backgrounds and distinguishable from other SUSY
processes. In addition, we find small regions of SUGRA parameter space where
\te\te, \tz_2\tz_2 and \tnu_L\tnu_L production yields spectacular events
with up to four isolated leptons. The combined regions of parameter space
explorable by LEP2 are compared with the reach of Tevatron Main Injector era
experiments. Finally, we comment on how the reach via the neutralino pair
channel is altered when the radiative electroweak symmetry breaking constraint
is relaxed.Comment: 22 page REVTEX file + 9 uuencoded figures; a uuencoded PS file with
PS figures is available via anonymous ftp at
ftp://hep.fsu.edu/preprints/baer/FSUHEP950501.u
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