548 research outputs found
On the Luminosities and Temperatures of Extended X-ray Emission from Planetary Nebulae
We examine mechanisms that may explain the luminosities and relatively low
temperatures of extended X-ray emission in planetary nebulae. By building a
simple flow structure for the wind from the central star during the proto, and
early, planetary nebulae phase, we estimate the temperature of the X-ray
emitting gas and its total X-ray luminosity. We conclude that in order to
account for the X-ray temperature and luminosity, both the evolution of the
wind from the central star and the adiabatic cooling of the post-shocked wind's
material must be considered. The X-ray emitting gas results mainly from shocked
wind segments that were expelled during the early planetary nebulae phase, when
the wind speed was moderate. Alternatively, the X-ray emitting gas may result
from a collimated fast wind blown by a companion to the central star. Heat
conduction and mixing between hot and cool regions are likely to occur in some
cases and may determine the detailed X-ray morphology of a nebula, but are not
required to explain the basic properties of the X-ray emitting gas.Comment: ApJ, submitted; 16 page
Contact binaries with additional components. III. The adaptive optics detections
We present results of the CFHT adaptive optics search for companions of a
homogeneous group of contact binary stars, as a contribution to our attempts to
prove a hypothesis that these binaries require a third star to become so close
as observed. In addition to companions directly discovered at separations of
>=1", we introduced a new method of AO image analysis utilizing distortions of
the AO diffraction ring pattern at separations of 0.07"-1". Very close
companions, with separations in the latter range were discovered in systems HV
Aqr, OO Aql, CK Boo, XY Leo, BE Scl, and RZ Tau. More distant companions were
detected in V402 Aur, AO Cam, V2082 Cyg. Our results provide a contribution to
the mounting evidence that the presence of close companions is a very common
phenomenon for very close binaries with orbital periods <1 day.Comment: Full Figs.4 and 5 are in
http://www.astro.utoronto.ca/~rucinski/Triples3
Chronic pain and severe disuse syndrome:long-term outcome of an inpatient multidisciplinary cognitive behavioural programme
Objective: Patients with chronic pain and severe disuse syndrome have pain with physiological, psychological and social adaptations. The duration and severity of complaints, combined with previously failed treatments, makes them unsuitable for treatment in primary care. Design: A prospective waiting list controlled study. Patients: A total of 32 patients with chronic pain for at least one year and severe disuse syndrome were included in an inpatient multidisciplinary cognitive behavioural treatment. Methods: Patients were assessed before the waiting list period, before the clinical phase, after the clinical phase and after follow-ups of 6 months and one year. The visual analogue scale for pain and fatigue were assessed. Muscle strength of the arms and legs, arm endurance and a 6-minute walking test were used to assess physical outcome. The Symptom Check-list-90, RAND-36, pain cognition list and the Tampa scale for kinesiophobia were used to assess psychological outcome. Results: Long-term significant (p <0.001) improvements were found for pain, fatigue, walking distance, muscle strength, anxiety, depression, somatization, negative self-efficacy, and catastrophizing in the intervention period. Conclusion: An inpatient multidisciplinary cognitive behavioural programme is beneficial for patients with chronic pain and a severe disuse syndrome
Marker assisted approach for incorporating durable rust resistance in popular Indian wheat cultivars
Item does not contain fulltextParkinson disease (PD) is common in long term care (LTC) facilities. The number of institutionalized patients with PD will rise sharply in the coming decades because of 2 concurrent phenomena: aging of the population leads to an increased PD prevalence and improved quality of care has led to a prolonged survival in advanced disease stages. Only a few studies have investigated the prevalence and clinical characteristics of patients with PD in LTC facilities. Even fewer studies have addressed the treatment strategies used to support these institutionalized patients, who are mostly in advanced stages of the disease. The available evidence suggests that current management of patients with PD in LTC facilities is less than optimal. In the Netherlands, and we suspect in many other countries, there are no formal guidelines for treating patients with PD who have been admitted to a LTC facility. In this review, we describe the epidemiology, clinical characteristics, and clinical management of patients with PD in LTC settings. We also address potentially modifiable elements of care and provide several recommendations to improve the management of PD in these facilities. We conclude by suggesting a possible guide for future research in this area
Programmable access-controlled and generic erasable PUF design and its applications
Physical unclonable functions (PUFs) have not only been suggested as a new key storage mechanism, butâin the form of so-called strong PUFsâalso as cryptographic primitives in advanced schemes, including key exchange, oblivious transfer, or secure multi-party computation. This notably extends their application spectrum, and has led to a sequence of publications at leading venues such as IEEE S&P, CRYPTO, and EUROCRYPT in the past. However, one important unresolved problem is that adversaries can break the security of all these advanced protocols if they gain physical access to the employed strong PUFs after protocol completion. It has been formally proven that this issue cannot be overcome by techniques on the protocol side alone, but requires resolution on the hardware levelâthe only fully effective known countermeasure being so-called erasable PUFs. Building on this work, this paper is the first to describe a generic method of how any given silicon strong PUF with digital CRP-interface can be turned into an erasable PUF. We describe how the strong PUF can be surrounded with a trusted control logic that allows the blocking (or âerasureâ) of single CRP. We implement our approach, which we call âGeniePUF,â on FPGA, reporting detailed performance data and practicality figures. Furthermore, we develop the first comprehensive definitional framework for erasable PUFs. Our work so re-establishes the effective usability of strong PUFs in advanced cryptographic applications, and in the realistic case, adversaries get access to the strong PUF after protocol completion. As an extension to earlier versions of this work, we also introduce a generalization of erasable PUFs in this paper, which we call programmable access-controlled PUFs (PAC PUFs). We detail their definition, and discuss various exemplary applications of theirs
The dynamical evolution of the circumstellar gas around low-and intermediate-mass stars I: the AGB
We have investigated the dynamical interaction of low- and-intermediate mass
stars (from 1 to 5 Msun) with their interstellar medium (ISM). In this first
paper, we examine the structures generated by the stellar winds during the
Asymptotic Giant Branch (AGB) phase, using a numerical code and the wind
history predicted by stellar evolution. The influence of the external ISM is
also taken into account. We find that the wind variations associated with the
thermal pulses lead to the formation of transient shells with an average
lifetime of 20,000 yr, and consequently do not remain recorded in the density
or velocity structure of the gas. The formation of shells that survive at the
end of the AGB occurs via two main processes: shocks between the shells formed
by two consecutive enhancements of the mass-loss or via continuous accumulation
of the material ejected by the star in the interaction region with the ISM. Our
models show that the mass of the circumstellar envelope increases appreciably
due to the ISM material swept up by the wind (up to 70 % for the 1 Msun stellar
model). We also point out the importance of the ISM on the deceleration and
compression of the external shells. According to our simulations, large regions
(up to 2.5 pc) of neutral gas surrounding the molecular envelopes of AGB stars
are expected. These large regions of gas are formed from the mass-loss
experienced by the star during the AGB evolution.Comment: 43 pages, 15 figures. Accepted for publication in the Astrophysical
Journa
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