Modification of radiation pressure due to cooperative scattering of light

Cooperative spontaneous emission of a single photon from a cloud of N atoms modifies substantially the radiation pressure exerted by a far-detuned laser beam exciting the atoms. On one hand, the force induced by photon absorption depends on the collective decay rate of the excited atomic state. On the other hand, directional spontaneous emission counteracts the recoil induced by the absorption. We derive an analytical expression for the radiation pressure in steady-state. For a smooth extended atomic distribution we show that the radiation pressure depends on the atom number via cooperative scattering and that, for certain atom numbers, it can be suppressed or enhanced.Comment: 8 pages, 2 Figure

Newtonian Collapse of Scalar Field Dark Matter

In this letter, we develop a Newtonian approach to the collapse of galaxy fluctuations of scalar field dark matter under initial conditions inferred from simple assumptions. The full relativistic system, the so called Einstein-Klein-Gordon, is reduced to the Schr\"odinger-Newton one in the weak field limit. The scaling symmetries of the SN equations are exploited to track the non-linear collapse of single scalar matter fluctuations. The results can be applied to both real and complex scalar fields.Comment: 4 pages RevTex4 file, 4 eps figure

Evolution of the Schr\"odinger--Newton system for a self--gravitating scalar field

Using numerical techniques, we study the collapse of a scalar field configuration in the Newtonian limit of the spherically symmetric Einstein--Klein--Gordon (EKG) system, which results in the so called Schr\"odinger--Newton (SN) set of equations. We present the numerical code developed to evolve the SN system and topics related, like equilibrium configurations and boundary conditions. Also, we analyze the evolution of different initial configurations and the physical quantities associated to them. In particular, we readdress the issue of the gravitational cooling mechanism for Newtonian systems and find that all systems settle down onto a 0--node equilibrium configuration.Comment: RevTex file, 19 pages, 26 eps figures. Minor changes, matches version to appear in PR

Supermassive black holes in scalar field galaxy halos

Ultra-light scalar fields provide an interesting alternative to WIMPS as halo dark matter. In this paper we consider the effect of embedding a supermassive black hole within such a halo, and estimate the absorption probability and the accretion rate of dark matter onto the black hole. We show that the accretion rate would be small over the lifetime of a typical halo, and hence that supermassive central black holes can coexist with scalar field halos.Comment: 5 pages RevTex4, no figures. Updated file to match published versio

Multidimensional quantum solitons with nondegenerate parametric interactions: Photonic and Bose-Einstein condensate environments

We consider the quantum theory of three fields interacting via parametric and repulsive quartic couplings. This can be applied to treat photonic chi((2)) and chi((3)) interactions, and interactions in atomic Bose-Einstein condensates or quantum Fermi gases, describing coherent molecule formation together with a-wave scattering. The simplest two-particle quantum solitons or bound-state solutions of the idealized Hamiltonian, without a momentum cutoff, are obtained exactly. They have a pointlike structure in two and three dimensions-even though the corresponding classical theory is nonsingular. We show that the solutions can be regularized with a momentum cutoff. The parametric quantum solitons have much more realistic length scales and binding energies than chi((3)) quantum solitons, and the resulting effects could potentially be experimentally tested in highly nonlinear optical parametric media or interacting matter-wave systems. N-particle quantum solitons and the ground state energy are analyzed using a variational approach. Applications to atomic/molecular Bose-Einstein condensates (BEC's) are given, where we predict the possibility of forming coupled BEC solitons in three space dimensions, and analyze superchemistry dynamics

Effect of a multipayer patient-centered medical home on health care utilization and quality: the rhode island chronic care sustainability initiative pilot program

Item does not contain fulltextIMPORTANCE The patient-centered medical home is advocated to reduce health care costs and improve the quality of care. OBJECTIVE To evaluate the effects of the pilot program of a multipayer patient-centered medical home on health care utilization and quality. DESIGN An interrupted time series design with propensity score-matched comparison practices, including multipayer claims data from 2 years before (October 1, 2006-September 30, 2008) and 2 years after (October 1, 2008-September 30, 2010) the launch of the pilot program. Uptake of the intervention was measured with audit data from the National Committee for Quality Assurance patient-centered medical home recognition process. SETTING Five independent primary care practices and 3 private insurers in the Rhode Island Chronic Care Sustainability Initiative. PARTICIPANTS Patients in 5 pilot and 34 comparison practices. INTERVENTIONS Financial support, care managers, and technical assistance for quality improvement and practice transformation. MAIN OUTCOMES AND MEASURES Hospital admissions, emergency department visits, and 6 process measures of quality of care (3 for diabetes mellitus and 3 for colon, breast, and cervical cancer screening). RESULTS The mean National Committee for Quality Assurance recognition scores of the pilot practices increased from 42 to 90 points of a possible 100 points. The pilot and comparison practices had statistically indistinguishable baseline patient characteristics and practice patterns, except for higher numbers of attributed member months per year in the pilot practices (31 130 per practice vs 14 779, P = .01) and lower rates of cervical cancer screening in the comparison practices. Although estimates of the emergency department visits and inpatient admissions of patients in the pilot practices trended toward lower utilization, the only significant difference was a lower rate of ambulatory care sensitive emergency department visits in the pilot practices. The Chronic Care Sustainability Initiative pilot program was associated with a reduction in ambulatory care-sensitive emergency department visits of approximately 0.8 per 1000 member months or approximately 11.6% compared with the baseline rate of 6.9 for emergency department visits per 1000 member months (P = .002). No significant improvements were found in any of the quality measures. CONCLUSION AND RELEVANCE After 2 years, a pilot program of a patient-centered medical home was associated with substantial improvements in medical home recognition scores and a significant reduction in ambulatory care sensitive emergency department visits. Although not achieving significance, there were downward trends in emergency department visits and inpatient admissions

Defining and measuring integrated patient care: promoting the next frontier in health care delivery.

Item does not contain fulltextIntegration of care is emerging as a central challenge of health care delivery, particularly for patients with multiple, complex chronic conditions. The authors argue that the concept of "integrated patient care" would benefit from further clarification regarding (a) the object of integration and (b) its essential components, particularly when constructing measures.To address these issues, the authors propose a definition of integrated patient care that distinguishes it from integrated delivery organizations, acknowledging that integrated organizational structures and processes may fail to produce integrated patient care. The definition emphasizes patients' central role as active participants in managing their own health by including patient centeredness as a key element of integrated patient care. Measures based on the proposed definition will enable empirical assessment of the potential relationships between the integration of organizations, the integration of patient care, and patient outcomes, providing valuable guidance to health systems reformers.1 februari 201

Development and Psychometric Analysis of the Revised Patient Perceptions of Integrated Care Survey

This article describes the development and psychometric testing of the Patient Perceptions of Integrated Care (PPIC 2.1) survey, which we administered to 12,364 Medicare beneficiaries who received treatment from 150 randomly selected physician organizations, receiving 3,067 responses (26%). Psychometric analyses, performed using two methods to adjust for respondent inherent optimism (as a measure of response tendency), supported a 6-factor, 22-item model with excellent fit. These factors were (1) Staff Knowledge about the Patient's Medical History, (2) Provider Support for the Patient's Self-Directed Care, (3) Test Result Communication, (4) Provider Knowledge of the Patient, (5) Provider Support for Medication Adherence and Home Health Management, and (6) Specialist Knowledge about the Patient's Medical History. Per Spearman-Brown prophesy calculations, reliability would exceed 0.7 for all factors at 33 or more responses per organization. The PPIC 2.1 survey can distinguish six dimensions of integrated patient care with high physician organization-level reliability at reasonable sample sizes