Local field effect as a function of pulse duration

In this note we give semiclassical consideration of the role of pulse duration in observation of local field effects in the regime of optical switching. We show that the main parameter governing local field influence is the ratio of peak Rabi frequency corresponding to medium inversion and Lorentz frequency of the medium. To obtain significant local field effect, this parameter should be near unity that is valid only for long enough pulses. We also discuss the role of relaxation and pulse shape in this processes.Comment: 4 pages, 3 figure

Nonlinear Transport Near a Quantum Phase Transition in Two Dimensions

The problem of non-linear transport near a quantum phase transition is solved within the Landau theory for the dissipative insulator-superconductor phase transition in two dimensions. Using the non-equilibrium Schwinger round-trip Green function formalism, we obtain the scaling function for the non-linear conductivity in the quantum disordered regime. We find that the conductivity scales as $E^2$ at low field but crosses over at large fields to a universal constant on the order of $e^2/h$. The crossover between these two regimes obtains when the length scale for the quantum fluctuations becomes comparable to that of the electric field within logarithmic accuracy.Comment: 4.15 pages, no figure

Fermi-Edge Singularities in the Mesoscopic X-Ray Edge Problem

We study the x-ray edge problem for a chaotic quantum dot or nanoparticle displaying mesoscopic fluctuations. In the bulk, x-ray physics is known to produce deviations from the naively expected photoabsorption cross section in the form of a peaked or rounded edge. For a coherent system with chaotic dynamics, we find substantial changes and in particular that a photoabsorption cross section showing a rounded edge in the bulk will change to a slightly peaked edge on average as the system size is reduced to a mesoscopic (coherent) scale.Comment: 4 pages, 3 figures, final version as published in PR

A prototype system for detecting the radio-frequency pulse associated with cosmic ray air showers

The development of a system to detect the radio-frequency (RF) pulse associated with extensive air showers of cosmic rays is described. This work was performed at the CASA/MIA array in Utah, with the intention of designing equipment that can be used in conjunction with the Auger Giant Array. A small subset of data (less than 40 out of a total of 600 hours of running time), taken under low-noise conditions, permitted upper limits to be placed on the rate for pulses accompanying showers of energies around $10^{17}$ eV.Comment: 53 pages, LaTeX, 19 figures, published in Nuclear Instruments and Methods. Revised version; some references update

Properties of iterative Monte Carlo single histogram reweighting

We present iterative Monte Carlo algorithm for which the temperature variable is attracted by a critical point. The algorithm combines techniques of single histogram reweighting and linear filtering. The 2d Ising model of ferromagnet is studied numerically as an illustration. In that case, the iterations uncovered stationary regime with invariant probability distribution function of temperature which is peaked nearly the pseudocritical temperature of specific heat. The sequence of generated temperatures is analyzed in terms of stochastic autoregressive model. The error of histogram reweighting can be better understood within the suggested model. The presented model yields a simple relation, connecting variance of pseudocritical temperature and parameter of linear filtering.Comment: 3 figure

When doctors lead organizational innovation: Lessons from a clinical directorate in Portugal

The need of improving health services has brought professional leaders into management positions as hybrid managers (HMs). There is much discussion about the relative autonomy of HMs and if they effectively improve health services. We focus on health care service controlled by HMs to provide evidence on if and how HMs contribute to organizational innovation.info:eu-repo/semantics/publishedVersio

Hybrid management, organizational configuration, and medical professionalism: evidence from the establishment of a clinical directorate in Portugal

Background: The need of improving the governance of healthcare services has brought health professionals into management positions. However, both the processes and outcomes of this policy change highlight differences among the European countries. This article provides in-depth evidence that neither quantitative data nor cross-country comparisons have been able to provide regarding the influence of hybrids in the functioning of hospital organizations and impact on clinicians' autonomy and exposure to hybridization. Methods: The study was designed to witness the process of institutional change from the inside and while that process was underway. It reports a case study carried out in a public hospital in Portugal when the establishment of a clinical directorate was being negotiated. Data collection comprises semi-structured interviews with general managers and surgeons complemented with observations. Results: The clinical directorate under study illustrates a divisionalized professional bureaucracy model that combines features of professional bureaucracies and divisionalized forms. The hybrid manager is key to understand the extent to which practising clinicians are more accountable and to whom given that managerial tools of control have not been strengthened, and trust-based relations allow them to keep professional autonomy untouched. In sum, clinicians are allowed to profit from their activity and to perform autonomously from the hospital's board of directors. The advantageous conditions enjoyed by the clinical directorate intensify internal re-stratification in medicine, thus suggesting forms of divisionalized medical professionalism grounded in organizational dynamics. Conclusion: It is discussed the extent to which policy change to the governance of health organizations regarding the relationship between medicine and management is subject to specific constraints at the workplace level, thus conditioning the expected outcomes of policy setting. The study also highlights the role of hybrid managers in determining the extent to which practising professionals are more accountable to managerial criteria. The overall conclusion is that although medical and managerial values link to each other, clinicians reconfigure managerial criteria according to specific interests. Ultimately, medical autonomy and authority may be reinforced in organizational settings subject to NPM-driven reforms.info:eu-repo/semantics/publishedVersio

Fluctuations of g-factors in metal nanoparticles: Effects of electron-electron interaction and spin-orbit scattering

We investigate the combined effect of spin-orbit scattering and electron-electron interactions on the probability distribution of $g$-factors of metal nanoparticles. Using random matrix theory, we find that even a relatively small interaction strength %(ratio of exchange constant $J$ and mean level %spacing \spacing $\simeq 0.3$) significantly increases $g$-factor fluctuations for not-too-strong spin-orbit scattering (ratio of spin-orbit rate and single-electron level spacing 1/\tau_{\rm so} \spacing \lesssim 1), and leads to the possibility to observe $g$-factors larger than two.Comment: RevTex, 2 figures inserte