454 research outputs found
From maid to mother: Transforming facilities, staff training, and caregiver dignity in an institutional facility for young children in Nepal
This article provides a case study of a project to improve the health, safety, and development of children birth to 6 years old in a large orphanage in Nepal. Two interventions were conducted: improvement of physical infrastructure and training, mentoring, and support for caregiving staff. As a result of these interventions, positive outcomes in terms of children\u27s health and development have been observed, including reduction of communicable diseases and increased social interactions with caregivers. As part of the new training initiative, the caregivers began to meet regularly to share their ideas and experiences, and came to realize their vital role in the holistic development of the children in their care. One important change was a greater sense of dignity for the caregivers. The caregivers were formerly called Maids(Aaya), but asked to be called Mothers(Aama). The project also faced challenges, including communication barriers related to organizational structure
Casimir force between sharp-shaped conductors
Casimir forces between conductors at the sub-micron scale cannot be ignored
in the design and operation of micro-electromechanical (MEM) devices. However,
these forces depend non-trivially on geometry, and existing formulae and
approximations cannot deal with realistic micro-machinery components with sharp
edges and tips. Here, we employ a novel approach to electromagnetic scattering,
appropriate to perfect conductors with sharp edges and tips, specifically to
wedges and cones. The interaction of these objects with a metal plate (and
among themselves) is then computed systematically by a multiple-scattering
series. For the wedge, we obtain analytical expressions for the interaction
with a plate, as functions of opening angle and tilt, which should provide a
particularly useful tool for the design of MEMs. Our result for the Casimir
interactions between conducting cones and plates applies directly to the force
on the tip of a scanning tunneling probe; the unexpectedly large temperature
dependence of the force in these configurations should attract immediate
experimental interest
Casimir effect with nonlocal boundary interactions
We derive a general expression for the Casimir energy corresponding to two
flat parallel mirrors in d+1 dimensions, described by nonlocal interaction
potentials. For a real scalar field, the interaction with the mirrors is
implemented by a term which is a quadratic form in the field, with a nonlocal
kernel. The resulting expression for the energy is a function of the parameters
that define the nonlocal kernel. We show that the general expression has the
correct limit in the zero width case, and also present the exact solution for a
particular case.Comment: 13 pages, LaTeX; minor misprints correcte
The Casimir effect as scattering problem
We show that Casimir-force calculations for a finite number of
non-overlapping obstacles can be mapped onto quantum-mechanical billiard-type
problems which are characterized by the scattering of a fictitious point
particle off the very same obstacles. With the help of a modified Krein trace
formula the genuine/finite part of the Casimir energy is determined as the
energy-weighted integral over the log-determinant of the multi-scattering
matrix of the analog billiard problem. The formalism is self-regulating and
inherently shows that the Casimir energy is governed by the infrared end of the
multi-scattering phase shifts or spectrum of the fluctuating field. The
calculation is exact and in principle applicable for any separation(s) between
the obstacles. In practice, it is more suited for large- to medium-range
separations. We report especially about the Casimir energy of a fluctuating
massless scalar field between two spheres or a sphere and a plate under
Dirichlet and Neumann boundary conditions. But the formalism can easily be
extended to any number of spheres and/or planes in three or arbitrary
dimensions, with a variety of boundary conditions or non-overlapping
potentials/non-ideal reflectors.Comment: 14 pages, 2 figures, plenary talk at QFEXT07, Leipzig, September
2007, some typos correcte
Towards a Theory of Molecular Forces between Deformed Media
A macroscopic theory for the molecular or Casimir interaction of dielectric
materials with arbitrarily shaped surfaces is developed. The interaction is
generated by the quantum and thermal fluctuations of the electromagnetic field
which depend on the dielectric function of the materials. Using a path integral
approach for the electromagnetic gauge field, we derive an effective Gaussian
action which can be used to compute the force between the objects. No
assumptions about the independence of the shape and material dependent
contributions to the interaction are made. In the limiting case of flat
surfaces our approach yields a simple and compact derivation of the Lifshitz
theory for molecular forces. For ideal metals with arbitrarily deformed
surfaces the effective action can be calculated explicitly. For the general
case of deformed dielectric materials the applicability of perturbation theory
and numerical techniques to the evaluation of the force from the effective
action is discussed.Comment: 15 pages, 1 figur
Importance of continued activation of thrombin reflected by fibrinopeptide A to the efficacy of thrombolysis
Factors responsible for initial success or failure of coronary thrombolysis and persistent recanalization or early reocclusion have not been thoroughly elucidated. Both adequate initial clot lysis and preclusion of rethrombosis are required. Failure may reflect clot lysis followed immediately or somewhat later by rethrombosis. To determine whether differences in the intensity and persistence of the activation of thrombin are determinants of success or failure of recanalization, plasma fibrinopeptide A, a fibrinogen product liberated by thrombin, was serially assayed in 19 patients treated with intravenous streptokinase. In patients exhibiting recanalization (n = 9), plasma fibrinopeptide A decreased after administration of streptokinase but before administration of heparin. In patients without initially apparent recanalization, fibrinopeptide A increased, suggesting ongoing thrombosis, and subsequently decreased promptly after heparin. In patients with initial recanalization followed by overt reocclusion the pattern was different. Despite recanalization, fibrinopeptide A continued to rise markedly. Elevations persisted despite administration of heparin. Thus, inhibition of activation of thrombin is associated with successful recanalization. Conversely, persistent activation of thrombin may be a predisposing factor to both apparent initial failure of recanalization and nvprt early reocclusion
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Exploring the Role of Natural Gas in U.S. Trucking (Revised Version)
The recent emergence of natural gas as an abundant, inexpensive fuel in the United States could prompt a momentous shift in the level of natural gas utilized in the transportation sector. The cost advantage of natural gas vis-à -vis diesel fuel is particularly appealing for vehicles with a high intensity of travel and thus fuel use. Natural gas is already a popular fuel for municipal and fleet vehicles such as transit buses and taxis. In this paper, we investigate the possibility that natural gas could be utilized to provide fuel cost savings, geographic supply diversity and environmental benefits for the heavy-duty trucking sector and whether it can enable a transition to lower carbon transport fuels. We find that a small, cost-effective intervention in markets could support a transition to a commercially sustainable natural gas heavyduty fueling system in the state of California and that this could also advance some of the state’s air quality goals. Our research shows that an initial advanced natural gas fueling system in California could facilitate the expansion to other U.S. states. Such a network would enable a faster transition to renewable natural gas or biogas and waste-to-energy pathways. Stricter efficiency standards for natural gas Class 8 trucks and regulation of methane leakage along the natural gas supply chain would be necessary for natural gas to contribute substantially to California’s climate goals as a trucking fuel. To date, industry has favored less expensive technologies that do not offer the highest level of environmental performance
Fluctuation induced quantum interactions between compact objects and a plane mirror
The interaction of compact objects with an infinitely extended mirror plane
due to quantum fluctuations of a scalar or electromagnetic field that scatters
off the objects is studied. The mirror plane is assumed to obey either
Dirichlet or Neumann boundary conditions or to be perfectly reflecting. Using
the method of images, we generalize a recently developed approach for compact
objects in unbounded space [1,2] to show that the Casimir interaction between
the objects and the mirror plane can be accurately obtained over a wide range
of separations in terms of charge and current fluctuations of the objects and
their images. Our general result for the interaction depends only on the
scattering matrices of the compact objects. It applies to scalar fields with
arbitrary boundary conditions and to the electromagnetic field coupled to
dielectric objects. For the experimentally important electromagnetic Casimir
interaction between a perfectly conducting sphere and a plane mirror we present
the first results that apply at all separations. We obtain both an asymptotic
large distance expansion and the two lowest order correction terms to the
proximity force approximation. The asymptotic Casimir-Polder potential for an
atom and a mirror is generalized to describe the interaction between a
dielectric sphere and a mirror, involving higher order multipole
polarizabilities that are important at sub-asymptotic distances.Comment: 19 pages, 7 figure
A preliminary examination of sexual and physical victimization 6 months after recent rape
One in four US women will experience a completed or attempted rape in their lifetime, and more than 50% of survivors will experience two or more rapes. Rape and physical violence also co-occur. Multiple experiences of sexual and physical violence are associated with elevated mental and physical health problems. This secondary analysis examined the prevalence and correlates of experiencing sexual or physical violence within 6 months of a sexual assault medical forensic exam (SAMFE). Between May 2009 and December 2013, 233 female rape survivors aged 15 and older were enrolled in a randomized controlled trial during a SAMFE in the emergency department (ED). Demographics, rape characteristics, distress at the ED, and pre-rape history of sexual or physical victimization were assessed. New sexual and physical victimization was assessed 6 months after the SAMFE via telephone interview. Six months after the exam, 21.7% reported a new sexual or physical victimization. Predictors of revictimization during follow-up included sexual or physical victimization prior to the index rape, making less than 10,000 annually were associated with revictimization. Factors assessed at the ED can inform subsequent victimization risk. More research is needed to prevent revictimization among recent rape victims. Policies to provide financial support to recent rape victims and/or targeted prevention for those with pre-rape victimization at the SAMFE could reduce revictimization risk
Pregnenolone and pregnenolone sulfate metabolism by human fetal testes in vitro
Homogenates of testes from human fetuses of 12-16 weeks gestation were incubated in vitro with pregnenolone-4-14C and pregnenolone-7-3H-sulfate. Dehydroepiandrosterone sulfate and pregnenediol sulfate, each bearing the tritium label only, were identified in the conjugated fraction. Progesterone, 17[alpha]-hydroxyprogesterone, 17[alpha]-hydroxypregnenolone, dehydroepiandrosterone, androstenedione and testosterone, each bearing both a tritium and 14C-label, were identified in the organic fraction. In a similar incubation, with pregnenolone-7-3H-sulfate-35S as substrate, the direct conversion to 17[alpha]-hydroxypregnenolone sulfate was demonstrated. The presence of slight sulfatase activity was also noted. The direct metabolism of steroid sulfates and the presence of sulfatase activity in this fetal tissue and the possible significance of these findings in the developing male fetus are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32735/1/0000104.pd
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