9,341 research outputs found
Scattering from Solutions of Star Polymers
We calculate the scattering intensity of dilute and semi-dilute solutions of
star polymers. The star conformation is described by a model introduced by
Daoud and Cotton. In this model, a single star is regarded as a spherical
region of a semi-dilute polymer solution with a local, position dependent
screening length. For high enough concentrations, the outer sections of the
arms overlap and build a semi-dilute solution (a sea of blobs) where the inner
parts of the actual stars are embedded. The scattering function is evaluated
following a method introduced by Auvray and de Gennes. In the dilute regime
there are three regions in the scattering function: the Guinier region (low
wave vectors, q R << 1) from where the radius of the star can be extracted; the
intermediate region (1 << q R << f^(2/5)) that carries the signature of the
form factor of a star with f arms: I(q) ~ q^(-10/3); and a high wavevector zone
(q R >> f^(2/5)) where the local swollen structure of the polymers gives rise
to the usual q^(-5/3) decay. In the semi-dilute regime the different stars
interact strongly, and the scattered intensity acquires two new features: a
liquid peak that develops at a reciprocal position corresponding to the
star-star distances; and a new large wavevector contribution of the form
q^(-5/3) originating from the sea of blobs.Comment: REVTeX, 12 pages, 4 eps figure
A experiência da Embrapa Meio Ambiente com a certificação ISO 9001 como um modelo de gestão da qualidade numa instituição de pesquisa e desenvolvimento.
A história da certificação ISO 9001 da Embrapa Meio Ambiente.
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Enriched elderly virtual profiles by means of a multidimensional integrated assessment platform
The pressure over Healthcare systems is increasing in most developed countries. The generalized aging of the population is one of the main causes. This situation is even worse in underdeveloped, sparsely populated regions like Extremadura in Spain or Alentejo in Portugal. The authors propose to use the Situational-Context, a technique to seamlessly adapt Internet of Things systems to the needs and preferences of their users, for virtually modeling the elderly. These models could be used to enhance the elderly experience when using those kind of systems without raising the need for technical skills or the costs of implementing such systems by the regional healthcare systems. In this paper, the integration of a multidimensional integrated assessment platform with such virtual profiles is presented. The assessment platform provides and additional source of information for the virtual profiles that is used to better adapt existing systems to the elders needs
Star formation in low density HI gas around the Elliptical Galaxy NGC2865
Interacting galaxies surrounded by HI tidal debris are ideal sites for the
study of young clusters and tidal galaxy formation. The process that triggers
star formation in the low-density environments outside galaxies is still an
open question. New clusters and galaxies of tidal origin are expected to have
high metallicities for their luminosities. Spectroscopy of such objects is,
however, at the limit of what can be done with existing 8-10m class telescopes,
which has prevented statistical studies of these objects. NGC2865 is an
UV-bright merging elliptical galaxy with shells and extended HI tails. The
regions observed in this work were previously detected using multi-slit imaging
spectroscopy. We obtain new multislit spectroscopy of six young star-forming
regions around NGC2865, to determine their redshifts and metallicities. The six
emission-line regions are located 16-40 kpc from NGC2865 and they have similar
redshifts. They have ages of ~10Myears and an average metallicity of
12+log(O/H) ~ 8.6, suggesting a tidal origin for the regions. It is noted that
they coincide with an extended HI tail, which has projected density of N
< 10 cm, and displays a low surface brightness counterpart. These
regions may represent the youngest of the three populations of star clusters
already identified in NGC2865. The high, nearly-solar, oxygen abundances found
for the six regions in the vicinity of NGC2865 suggest that they were formed by
pre-enriched material from the parent galaxy, from gas removed during the last
major merger. Given the mass and the location of the HII regions, we can
speculate that these young star-forming regions are potential precursors of
globular clusters that will be part of the halo of NGC2865 in the future. Our
result supports the use of the multi-slit imaging spectroscopy as a useful tool
for finding nearly-formed stellar systems around galaxies.Comment: 7 pages, 2 figures accepted in A&
Influencia de doses e volumes de aplicação na eficácia do glifosato no controle de plantas daninhas em seringal em formação.
Os objetivos deste trabalho foram avaliar a viabilidade da aplicação de glifosato em pos-emergencia no controle de ervas em seringueira em formação e determinar o efeito de doses de herbicidas e volume de calda aplicados com aparelho rotativo que produz goticulas de diametro controlado (CDA), em ultra baixo e baixo volume, comparado com aparelho tradicional, em medio volume de calda.bitstream/item/67392/1/CPAF-RO-DOCUMENTOS-30-INFLUENCIA-DE-DOSES-E-VOLUMES-DE-APLICACAO-NA-EFICACIA-DO-GLIFOSATO-NO-CONT.pd
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More than a feeling: A unified view of stress measurement for population science.
Stress can influence health throughout the lifespan, yet there is little agreement about what types and aspects of stress matter most for human health and disease. This is in part because "stress" is not a monolithic concept but rather, an emergent process that involves interactions between individual and environmental factors, historical and current events, allostatic states, and psychological and physiological reactivity. Many of these processes alone have been labeled as "stress." Stress science would be further advanced if researchers adopted a common conceptual model that incorporates epidemiological, affective, and psychophysiological perspectives, with more precise language for describing stress measures. We articulate an integrative working model, highlighting how stressor exposures across the life course influence habitual responding and stress reactivity, and how health behaviors interact with stress. We offer a Stress Typology articulating timescales for stress measurement - acute, event-based, daily, and chronic - and more precise language for dimensions of stress measurement
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