2,538 research outputs found
Narrow-escape-time problem: the imperfect trapping case
We present a master equation approach to the \emph{narrow escape time} (NET)
problem, i.e. the time needed for a particle contained in a confining domain
with a single narrow opening, to exit the domain for the first time. We
introduce a finite transition probability, , at the narrow escape window
allowing the study of the imperfect trapping case. Ranging from 0 to ,
allowed the study of both extremes of the trapping process: that of a
highly deficient capture, and situations where escape is certain ("perfect
trapping" case). We have obtained analytic results for the basic quantity
studied in the NET problem, the \emph{mean escape time} (MET), and we have
studied its dependence in terms of the transition (desorption) probability over
(from) the surface boundary, the confining domain dimensions, and the finite
transition probability at the escape window. Particularly we show that the
existence of a global minimum in the NET depends on the `imperfection' of the
trapping process. In addition to our analytical approach, we have implemented
Monte Carlo simulations, finding excellent agreement between the theoretical
results and simulations.Comment: 9 page
Mixing of ultracold atomic clouds by merging of two magnetic traps
We demonstrate a method to make mixtures of ultracold atoms that does not
make use of a two-species magneto-optical trap. We prepare two clouds of 87Rb
atoms in distinct magnetic quadrupole traps and mix the two clouds by merging
the traps. For correctly chosen parameters the mixing can be done essentially
without loss of atoms and with only minor heating. The basic features of the
process can be accounted for by a classical simulation of particle
trajectories. Such calculations indicate that mixing of different mass species
is also feasible, opening the way for using the method as a starting point for
making quantum gas mixtures.Comment: 12 pages, 13 figures. Fig. 10 corrected. Fig. 13 updated with more
points and better statistics. A couple of paragraphs rephrased and typos
corrected. References update
Nova Geminorum 1912 and the Origin of the Idea of Gravitational Lensing
Einstein's early calculations of gravitational lensing, contained in a
scratch notebook and dated to the spring of 1912, are reexamined. A hitherto
unknown letter by Einstein suggests that he entertained the idea of explaining
the phenomenon of new stars by gravitational lensing in the fall of 1915 much
more seriously than was previously assumed. A reexamination of the relevant
calculations by Einstein shows that, indeed, at least some of them most likely
date from early October 1915. But in support of earlier historical
interpretation of Einstein's notes, it is argued that the appearance of Nova
Geminorum 1912 (DN Gem) in March 1912 may, in fact, provide a relevant context
and motivation for Einstein's lensing calculations on the occasion of his first
meeting with Erwin Freundlich during a visit in Berlin in April 1912. We also
comment on the significance of Einstein's consideration of gravitational
lensing in the fall of 1915 for the reconstruction of Einstein's final steps in
his path towards general relativity.Comment: 31 p
Nurses in expanded roles to strengthen community-based health promotion and chronic care: Policy implications from an international perspective; A commentary
© 2018 The Author(s). Chronic conditions and health inequalities are increasing worldwide. Against this backdrop, several countries, including Israel, have expanded the roles of nurses as one measure to strengthen the primary care workforce. In Israel, community nurses work in expanded roles with increased responsibilities for patients with chronic conditions. They also work increasingly in the field of health promotion and disease prevention. Common barriers to role change in Israel are mirrored by other countries. Barriers include legal and financial restrictions, resistance by professional associations, inflexible labor markets and lack of resources. Policies should be revisited and aligned across education, financing and labor markets, to enable nurses to practice in the expanded roles. Financial incentives can accelerate the uptake of new, expanded roles so that all patients including vulnerable population groups, benefit from equitable and patient-centered service delivery in the communities
Quantitative study of molecular N_2 trapped in disordered GaN:O films
The structure of disordered GaN:O films grown by ion-assisted deposition is
investigated using x-ray absorption near-edge spectroscopy and Raman
spectroscopy. It is found that between 4 and 21 % of the nitrogen in the films
is in the form of molecular N_2 that interacts only weakly with the surrounding
matrix. The anion to cation ratio in the GaN:O host remains close to unity, and
there is a close correlation between the N_2 fraction, the level of oxygen
impurities, and the absence of short-range order in the GaN:O matrix.Comment: 5 pages, 3 figure
CURRENT STATUS OF THE BENCHMARK DATABASE BEMEDA
Open science is an important attribute for developing new approaches. Especially, the data component plays a significant role. The FAIR principle provides a good orientation towards open data. One part of FAIR is findability. Thus, domain specific dataset search platforms were developed: the Earth Observation Database and our Benchmark Metadata Database (BeMeDa). In addition to the search itself, the datasets found by this platforms can be compared with each other with regard to their interoperability. We compare these two platforms and present an update of our platform BeMeDa. This update includes additional location information about the datasets and a new frontend design with improved usability. We rely on user feedback for further improvements and enhancements
Four-year update of the EXIST-2 study
Objectives We examined the long-term effects of everolimus in patients with
renal angiomyolipoma associated with tuberous sclerosis complex or sporadic
lymphangioleiomyomatosis. Methods Following favorable results from the double-
blind core phase of EXIST-2 (NCT00790400), patients were allowed to receive
open-label everolimus (extension phase). Patients initially randomly assigned
to everolimus continued on the same dose; those who were receiving placebo
crossed over to everolimus 10 mg/day. Dose modifications were based on
tolerability. The primary end point was angiomyolipoma response rate, defined
as a ≥50% reduction from baseline in the sum volume of target renal
angiomyolipomas in the absence of new target angiomyolipomas, kidney volume
increase of >20% from nadir, and angiomyolipoma-related bleeding grade ≥2. The
key secondary end point was safety. Results Of the 112 patients who received
≥1 dose of everolimus, 58% (95% CI, 48.3% to 67.3%) achieved angiomyolipoma
response. Almost all patients (97%) experienced reduction in renal lesion
volumes at some point during the study period. Median duration of everolimus
exposure was 46.9 months. Sixteen (14.3%) patients experienced angiomyolipoma
progression at some point in the study. No angiomyolipoma-related bleeding or
nephrectomies were reported. One patient on everolimus underwent embolization
for worsening right flank pain. Subependymal giant cell astrocytoma lesion
response was achieved in 48% of patients and skin lesion response in 68% of
patients. The most common adverse events suspected to be treatment-related
were stomatitis (42%), hypercholesterolemia (30.4%), acne (25.9%), aphthous
stomatitis and nasopharyngitis (each 21.4%). Ten (8.9%) patients withdrew
because of an adverse event. Renal function remained stable, and the frequency
of emergent adverse events generally decreased over time. Conclusions
Everolimus treatment remained safe and effective over approximately 4 years.
The overall risk/benefit assessment supports the use of everolimus as a viable
treatment option for angiomyolipoma associated with tuberous sclerosis complex
or sporadic lymphangioleiomyomatosis. Trial registration ClinicalTrials.gov
NCT0079040
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