29,126 research outputs found
The Changing Face of Medicine: Women Doctors and the Evolution of Health Care in America
[Excerpt] This book is a case study of one profession that plays a key role in the health care sector, which now represents about one seventh of the U.S. economy. It examines the most dramatic demographic change in this sector in the last century. But the issues we raise are likely to be of interest more broadly for what they say about the changing roles of women in contemporary society. Women\u27s entry into medicine is taken as dramatic evidence that the barriers to opportunity for women are rapidly falling in America. Does the experience of female physicians to date bear out this optimistic view? An alternative view is that gender roles remain deeply entrenched in our institutions and culture. Specifically, the gender division of household labor continues to constrain the choices of all women. The trade-offs between work and family may be clearest in the most demanding professions, such as law and medicine, which require a high degree of professional devotion.
Our study builds on the fine histories of women in medicine written by Walsh, Morantz-Sanchez, and More. The analysis presented here focuses on the period since 1970, thus complementing the important studies of Bowman and colleagues and Bickel. Lorber examined the experiences of the generation of women who pioneered the transformation of the profession. With the benefit of additional decades of perspective, we are in a position to examine whether the role of gender in medicine is changing
Radiative transitions involving the (2p2)(3 Pe) metastable autodetaching of H(-)
The absorption coefficient for the free-bound transition H (ls) + e(-)+ h omega yields H(-)(2 sq p,(3)P(e)) is calculated (together with the differential emission rate for the inverse process) using ls - 2s - 2p close coupling continuum wave functions and a Hylleraas bound state wave function. A maximum in the absorption and emission spectra is found to occur at a photon wavelength of 1219.5 A, which is 2 A closer to the Lyman alpha line than predicted by the calculations of Drake, and is in closer agreement with the stellar absorption feature identified by Heap and Stecher. The free-bound absorption process appears to be a significant source of continuous ultraviolet opacity
The early expansion and evolutionary dynamics of POU class genes.
The POU genes represent a diverse class of animal-specific transcription factors that play important roles in neurogenesis, pluripotency, and cell-type specification. Although previous attempts have been made to reconstruct the evolution of the POU class, these studies have been limited by a small number of representative taxa, and a lack of sequences from basally branching organisms. In this study, we performed comparative analyses on available genomes and sequences recovered through "gene fishing" to better resolve the topology of the POU gene tree. We then used ancestral state reconstruction to map the most likely changes in amino acid evolution for the conserved domains. Our work suggests that four of the six POU families evolved before the last common ancestor of living animals-doubling previous estimates-and were followed by extensive clade-specific gene loss. Amino acid changes are distributed unequally across the gene tree, consistent with a neofunctionalization model of protein evolution. We consider our results in the context of early animal evolution, and the role of POU5 genes in maintaining stem cell pluripotency
Engineering Quantum States, Nonlinear Measurements, and Anomalous Diffusion by Imaging
We show that well-separated quantum superposition states, measurements of
strongly nonlinear observables, and quantum dynamics driven by anomalous
diffusion can all be achieved for single atoms or molecules by imaging
spontaneous photons that they emit via resonance florescence. To generate
anomalous diffusion we introduce continuous measurements driven by L\'evy
processes, and prove a number of results regarding their properties. In
particular we present strong evidence that the only stable L\'evy density that
can realize a strictly continuous measurement is the Gaussian.Comment: revtex4-1, 17 pages, 7 eps figure
A Monte Carlo Method for Modeling Thermal Damping: Beyond the Brownian-Motion Master Equation
The "standard" Brownian motion master equation, used to describe thermal
damping, is not completely positive, and does not admit a Monte Carlo method,
important in numerical simulations. To eliminate both these problems one must
add a term that generates additional position diffusion. He we show that one
can obtain a completely positive simple quantum Brownian motion, efficiently
solvable, without any extra diffusion. This is achieved by using a stochastic
Schroedinger equation (SSE), closely analogous to Langevin's equation, that has
no equivalent Markovian master equation. Considering a specific example, we
show that this SSE is sensitive to nonlinearities in situations in which the
master equation is not, and may therefore be a better model of damping for
nonlinear systems.Comment: 6 pages, revtex4. v2: numerical results for a nonlinear syste
Comparison of CDMA and FDMA for the MobileStar(sm) system
Spread-spectrum code division multiple access (CDMA) and single channel per carrier frequency division multiple access (FDMA) systems are compared for spectrum efficiency. CDMA is shown to have greater maximum throughput than FDMA for the MobileStar(sm) system which uses digital voice activated carriers and directive circularly polarized satellite antennas
Nucleation Induced Undulative Instability in Thin Films of nCB Liquid Crystals
A surface instability is reported in thin nematic films of 5CB and 8CB,
occurring near the nematic--isotropic phase transition.
Although this instability leads to patterns reminiscent of spinodal
dewetting, we show that it is actually based on a nucleation mechanism. Its
characteristic wavelength does not depend markedly on film thickness, but
strongly on the heating rate.Comment: 4 pages, 5 figure
Phonon number quantum jumps in an optomechanical system
We describe an optomechanical system in which the mean phonon number of a
single mechanical mode conditionally displaces the amplitude of the optical
field. Using homodyne detection of the output field we establish the conditions
under which phonon number quantum jumps can be inferred from the measurement
record: both the cavity damping rate and the measurement rate of the phonon
number must be much greater than the thermalization rate of the mechanical
mode. We present simulations of the conditional dynamics of the measured system
using the stochastic master equation. In the good-measurement limit, the
conditional evolution of the mean phonon number shows quantum jumps as phonons
enter and exit the mechanical resonator via the bath.Comment: 13 pages, 4 figures. minor revisions since first versio
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