3,193 research outputs found
Adaptive mutation using statistics mechanism for genetic algorithms
Copyright @ 2004 Springer-Verla
Stellar Disk Truncations: Where do we stand ?
In the light of several recent developments we revisit the phenomenon of
galactic stellar disk truncations. Even 25 years since the first paper on outer
breaks in the radial light profiles of spiral galaxies, their origin is still
unclear. The two most promising explanations are that these 'outer edges'
either trace the maximum angular momentum during the galaxy formation epoch, or
are associated with global star formation thresholds. Depending on their true
physical nature, these outer edges may represent an improved size
characteristic (e.g., as compared to D_25) and might contain fossil evidence
imprinted by the galaxy formation and evolutionary history. We will address
several observational aspects of disk truncations: their existence, not only in
normal HSB galaxies, but also in LSB and even dwarf galaxies; their detailed
shape, not sharp cut-offs as thought before, but in fact demarcating the start
of a region with a steeper exponential distribution of starlight; their
possible association with bars; as well as problems related to the
line-of-sight integration for edge-on galaxies (the main targets for truncation
searches so far). Taken together, these observations currently favour the
star-formation threshold model, but more work is necessary to implement the
truncations as adequate parameters characterising galactic disks.Comment: LaTeX, 10 pages, 6 figures, presented at the "Penetrating Bars
through Masks of Cosmic Dust" conference in South Africa, proceedings
published by Kluwer, and edited by Block, D.L., Freeman, K.C., Puerari, I., &
Groess, R; v3 to match published versio
Development of a multi-layered psychosocial care system for children in areas of political violence
Few psychosocial and mental health care systems have been reported for children affected by political violence in low- and middle income settings and there is a paucity of research-supported recommendations. This paper describes a field tested multi-layered psychosocial care system for children (focus age between 8-14 years), aiming to translate common principles and guidelines into a comprehensive support package. This community-based approach includes different overlapping levels of interventions to address varying needs for support. These levels provide assessment and management of problems that range from the social-pedagogic domain to the psychosocial, the psychological and the psychiatric domains. Specific intervention methodologies and their rationale are described within the context of a four-country program (Burundi, Sri Lanka, Indonesia and Sudan). The paper aims to contribute to bridge the divide in the literature between guidelines, consensus & research and clinical practice in the field of psychosocial and mental health care in low- and middle-income countries
AdS/BCFT Correspondence for Higher Curvature Gravity: An Example
We consider the effects of higher curvature terms on a holographic dual
description of boundary conformal field theory. Specifically, we consider
three-dimensional gravity with a specific combination of Ricci tensor square
and curvature scalar square, so called, new massive gravity. We show that a
boundary entropy and an entanglement entropy are given by similar expression
with those of the Einstein gravity case when we introduce an {\it effective}
Newton's constant and an {\it effective} cosmological constant. We also show
that the holographic g-theorem still holds in this extension, and we give some
comments about the central charge dependence of boundary entropy in the
holographic construction. In the same way, we consider new type black holes and
comment on the boundary profile. Moreover, we reproduce these results through
auxiliary field formalism in this specific higher curvature gravity.Comment: 27pages, minor corrections, accepted in JHE
The Dutch health insurance reform: switching between insurers, a comparison between the general population and the chronically ill and disabled
Background: On 1 January 2006 a number of far-reaching changes in the Dutch health insurance
system came into effect. In the new system of managed competition consumer mobility plays an
important role. Consumers are free to change their insurer and insurance plan every year. The idea
is that consumers who are not satisfied with the premium or quality of care provided will opt for
a different insurer. This would force insurers to strive for good prices and quality of care.
Internationally, the Dutch changes are under the attention of both policy makers and researchers.
Questions answered in this article relate to switching behaviour, reasons for switching, and
differences between population categories.
Methods: Postal questionnaires were sent to 1516 members of the Dutch Health Care Consumer
Panel and to 3757 members of the National Panel of the Chronically ill and Disabled (NPCD) in
April 2006. The questionnaire was returned by 1198 members of the Consumer Panel (response
79%) and by 3211 members of the NPCD (response 86%). Among other things, questions were
asked about choices for a health insurer and insurance plan and the reasons for this choice.
Results: Young and healthy people switch insurer more often than elderly or people in bad health.
The chronically ill and disabled do not switch less often than the general population when both
populations are comparable on age, sex and education.
For the general population, premium is more important than content, while the chronically ill and
disabled value content of the insurance package as well. However, quality of care is not important
for either group as a reason for switching.
Conclusion: There is increased mobility in the new system for both the general population and
the chronically ill and disabled. This however is not based on quality of care. If reasons for switching
are unrelated to the quality of care, it is hard to believe that switching influences the quality of care.
As yet there are no signs of barriers to switch insurer for the chronically ill and disabled. This
however could change in the future and it is therefore important to monitor changes.
Internal medicine specialists' attitudes towards working part-time: a comparison between 1996 and 2004
BACKGROUND: Although medical specialists traditionally hold negative views towards working part-time, the practice of medicine has evolved. Given the trend towards more part-time work and that there is no evidence that it compromises the quality of care, attitudes towards part-time work may have changed as well in recent years. The aim of this paper was to examine the possible changes in attitudes towards part-time work among specialists in internal medicine between 1996 and 2004. Moreover, we wanted to determine whether these attitudes were associated with individual characteristics (age, gender, investments in work) and whether attitudes of specialists within a partnership showed more resemblance than specialists' attitudes from different partnerships. METHODS: Two samples were used in this study: data of a survey conducted in 1996 and in 2004. After selecting internal medicine specialists working in general hospitals in The Netherlands, the sample consisted of 219 specialists in 1996 and 363 specialists in 2004. They were sent a questionnaire, including topics on the attitudes towards part-time work. RESULTS: Internal medicine specialists' attitudes towards working part-time became slightly more positive between 1996 and 2004. Full-time working specialists in 2004 still expressed concerns regarding the investments of part-timers in overhead tasks, the flexibility of task division, efficiency, communication and continuity of care. In 1996 gender was the only predictor of the attitude, in 2004 being a full- or a part-timer, age and the time invested in work were associated with this attitude. Furthermore, specialists' attitudes were not found to cluster much within partnerships. CONCLUSION: In spite of the increasing number of specialists working or preferring to work part-time, part-time practice among internal medicine specialists seems not to be fully accepted. The results indicate that the attitudes are no longer gender based, but are associated with age and work aspects such as the number of hours worked. Though there is little evidence to support them, negative ideas about the consequences of part-time work for the quality of care still exist. Policy should be aimed at removing the organisational difficulties related to part-time work and create a system in which part-time practice is fully integrated and accepted
30 inch Roll-Based Production of High-Quality Graphene Films for Flexible Transparent Electrodes
We report that 30-inch scale multiple roll-to-roll transfer and wet chemical
doping considerably enhance the electrical properties of the graphene films
grown on roll-type Cu substrates by chemical vapor deposition. The resulting
graphene films shows a sheet resistance as low as ~30 Ohm/sq at ~90 %
transparency which is superior to commercial transparent electrodes such as
indium tin oxides (ITO). The monolayer of graphene shows sheet resistances as
low as ~125 Ohm/sq with 97.4% optical transmittance and half-integer quantum
Hall effect, indicating the high-quality of these graphene films. As a
practical application, we also fabricated a touch screen panel device based on
the graphene transparent electrodes, showing extraordinary mechanical and
electrical performances
Translational Cancer Research: Balancing Prevention and Treatment to Combat Cancer Globally
Cancer research is drawing on the human genome project to develop new molecular-targeted treatments. This is an exciting but insufficient response to the growing, global burden of cancer, particularly as the projected increase in new cases in the coming decades is increasingly falling on developing countries. The world is not able to treat its way out of the cancer problem. However, the mechanistic insights from basic science can be harnessed to better understand cancer causes and prevention, thus underpinning a complementary public health approach to cancer control. This manuscript focuses on how new knowledge about the molecular and cellular basis of cancer, and the associated high-throughput laboratory technologies for studying those pathways, can be applied to population-based epidemiological studies, particularly in the context of large prospective cohorts with associated biobanks to provide an evidence base for cancer prevention. This integrated approach should allow a more rapid and informed translation of the research into educational and policy interventions aimed at risk reduction across a population
Cerebral activations related to ballistic, stepwise interrupted and gradually modulated movements in parkinson patients
Patients with Parkinson's disease (PD) experience impaired initiation and inhibition of movements such as difficulty to start/stop walking. At single-joint level this is accompanied by reduced inhibition of antagonist muscle activity. While normal basal ganglia (BG) contributions to motor control include selecting appropriate muscles by inhibiting others, it is unclear how PD-related changes in BG function cause impaired movement initiation and inhibition at single-joint level. To further elucidate these changes we studied 4 right-hand movement tasks with fMRI, by dissociating activations related to abrupt movement initiation, inhibition and gradual movement modulation. Initiation and inhibition were inferred from ballistic and stepwise interrupted movement, respectively, while smooth wrist circumduction enabled the assessment of gradually modulated movement. Task-related activations were compared between PD patients (N = 12) and healthy subjects (N = 18). In healthy subjects, movement initiation was characterized by antero-ventral striatum, substantia nigra (SN) and premotor activations while inhibition was dominated by subthalamic nucleus (STN) and pallidal activations, in line with the known role of these areas in simple movement. Gradual movement mainly involved antero-dorsal putamen and pallidum. Compared to healthy subjects, patients showed reduced striatal/SN and increased pallidal activation for initiation, whereas for inhibition STN activation was reduced and striatal-thalamo-cortical activation increased. For gradual movement patients showed reduced pallidal and increased thalamo-cortical activation. We conclude that PD-related changes during movement initiation fit the (rather static) model of alterations in direct and indirect BG pathways. Reduced STN activation and regional cortical increased activation in PD during inhibition and gradual movement modulation are better explained by a dynamic model that also takes into account enhanced responsiveness to external stimuli in this disease and the effects of hyper-fluctuating cortical inputs to the striatum and STN in particular
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