PubMed Health⌕ Search

Biomedical subjects

M Gabay

Publications and source records attributed to M Gabay.

18 recordsLinked to original sources
PubMed2006

Local switching of two-dimensional superconductivity using the ferroelectric field effect.

Correlated oxides display a variety of extraordinary physical properties including high-temperature superconductivity and colossal magnetoresistance. In these materials, strong electronic correlations often lead to competing ground states that are sensitive to many parameters--in particular the doping level--so that complex phase diagrams are observed. A flexible way to explore the role of doping is to tune the electron or hole concentration with electric fields, as is done in standard semiconductor field effect transistors. Here we demonstrate a model oxide system based on high-quality heterostructures in which the ferroelectric field effect approach can be studied. We use a single-crystal film of the perovskite superconductor Nb-doped SrTiO3 as the superconducting channel and ferroelectric Pb(Zr,Ti)O3 as the gate oxide. Atomic force microscopy is used to locally reverse the ferroelectric polarization, thus inducing large resistivity and carrier modulations, resulting in a clear shift in the superconducting critical temperature. Field-induced switching from the normal state to the (zero resistance) superconducting state was achieved at a well-defined temperature. This unique system could lead to a field of research in which devices are realized by locally defining in the same material superconducting and normal regions with 'perfect' interfaces, the interface being purely electronic. Using this approach, one could potentially design one-dimensional superconducting wires, superconducting rings and junctions, superconducting quantum interference devices (SQUIDs) or arrays of pinning centres.

Journal Article↗
PubMed2002

Bone mineral density in juvenile systemic lupus erythematosus.

We evaluated spine bone mineral density (BMD) in Brazilian children with juvenile systemic lupus erythematosus (JSLE) in order to detect potential predictors of reduction in bone mass. A cross-sectional study of BMD at the lumbar spine level (L2-L4) was conducted on 16 female JSLE patients aged 6-17 years. Thirty-two age-matched healthy girls were used as control. BMD at the lumbar spine was measured by dual-energy X-ray absorptiometry. Weight, height and pubertal Tanner stage were determined in patients and controls. Disease duration, mean daily steroid doses, mean cumulative steroid doses and JSLE activity measured by the systemic lupus erythematosus disease activity index (SLEDAI) were determined for all JSLE patients based on their medical charts. All parameters were used as potential determinant factors for bone loss. Lumbar BMD tended to be lower in the JSLE patients, however, this difference was not statistically significant (P = 0.10). No significant correlation was observed in JSLE girls between BMD and age, height, Tanner stage, disease duration, corticosteroid use or disease activity. We found a weak correlation between BMD and weight (r = 0.672). In the JSLE group we found no significant parameters to correlate with reduced bone mass. Disease activity and mean cumulative steroid doses were not related to BMD values. We did not observe reduced bone mass in female JSLE.

Absorptiometry, Photon↗
PubMed1994

Hospital wage and price controls: lessons from the Economic Stabilization Program.

The Clinton Administration has implied that short-run failures to control health care costs may cause a reexamination of wage and price controls as elements of comprehensive health care reform. The most recent imposition of mandatory wage and price controls was the Economic Stabilization Program (ESP) of the early 1970s. We analyze trends in hospitals' economic behavior and utilization before, during, and after ESP. We also review the relevant literature to estimate ESP's impact, considering other factors that influence hospital behavior. Noting important changes in the hospital industry since the 1970s, we conclude that ESP had limited effect and that similar controls would have little effect today.

Cost Control↗
PubMed1993

Lessons for states in inpatient ratesetting under the Boren Amendment.

Encouraged by a 1990 Supreme Court decision, Medicaid providers have challenged State inpatient ratesetting methodologies under the Boren Amendment. Procedurally, State assurances to the U.S. Department of Health and Human Services (DHHS) that payment rates meet the Amendment's requirements must be supported by findings based on a reasonably principled analysis. Substantively, rates may fall within a zone of reasonableness, but courts have differed in interpreting and applying the Amendment's terms. Although some courts have found special studies and written findings unnecessary, States that undertake economic analyses to support their findings are more likely to withstand judicial scrutiny. Several applicable economic analyses are proposed.

Centers for Medicare and Medicaid Services, U.S.↗
PubMed1987

Health status and medical expenditures: more evidence of a link.

The hypothesis that one must include life-style changes in order to accurately capture the true relationship between medical expenditures and health status is explored, using data from 22 countries over a 20-year period. A simultaneous model is estimated using a variety of indicators for life style as well as health status. Changes in life style, aging of the population and changes in occupational risk are modeled as influences on medical expenditures: medical expenditures and changes in life style are modeled as having direct influences on health status. The results are consistent with the existence of a positive link between medical expenditures and health status.

Female↗
PubMedDate not supplied

Nurse-midwifery. The beneficial alternative.

The number of nurse-midwife-attended births in U.S. hospitals has jumped ten-fold in the last 20 years, rising from just 19,686 in 1975 to 196,977 in 1994. Certified nurse-midwives (CNMs) focus on childbirth as a normal event, emphasizing the educational and psychosocial aspects of care and the judicious use of technological interventions. CNM care appears particularly well suited to help solve two difficult problems in U.S. obstetric care--our country's slow progress in improving the health status of newborns and the excessive use of medical interventions during childbirth. Despite the fact that CNM care has been found to be safe and cost-effective, only a small fraction of those pregnant women who could benefit from CNM care use midwifery services. Lack of consumer awareness is part of the problem, but barriers also exist to accessing CNM services. Sixty-four percent of CNM practices responding to a survey reported practice restrictions, most commonly due to state laws, hospital policies, and inappropriately restrictive physician back-up. One state, Florida, is aggressively promoting the use of CNM care as the standard of practice for healthy pregnant women.

Female↗