1,258 research outputs found
Change in root apical protein and peroxidase activity in response to aluminum in tolerant and sensitive maize inbred lines.
The effects of a short-term (80 min) exposure to 222 _uM aluminum (AI) on the protein content and expression and on peroxidase activity and isoenzymes in the primary root of maize were evaluated. Two inbred lines differing in their leveI of tolerance to AI were used: Cateto 237 (tolerant) and L36 (sensitive). The apical 20 mm of the primary root was divided into 2-mm-Iong segments that were analyzed for total protein content and peroxidase activity. These results demonstrate that the total protein content along the root apex was not affected by AI in the tolerant inbred line, but decreased in the sensitive line. In the apical 2 mm of the root of the sensitive line, the expression of low molecular weight proteins (43 kDa or smaller) was decreased. Expression of low molecular proteins increased in the tolerant inbred line, even though total protein content did not increase. This suggests that some of these proteins could play a role in metal tolerance, perhaps as binding peptides. While the peroxidase activity of the tolerant inbred line did not change with exposure to AI, peroxidase activity in the apical 6 mm of the root of the sensitive line decreased. The tolerant inbred line constitutively expressed more anionic peroxidase isoforms. These results demonstrate that maintenance of protein expression may be an important component of the plant's resistance to AI stress, and that resistance to AI stress is associated with the higher expression of anionic peroxidase isoforms
Contributions of theoretical essay for organizational studies.
O ensaio te?rico consiste em uma dimens?o pouco explorada no campo da pesquisa organizacional atual. Tal situa??o se deve a predomin?ncia da orienta??o funcionalista de pesquisa, que coloca como ponto central a produ??o de um saber embasado em rela??es de causa e efeito. Neste trabalho visa-se tornar claro outras possibilidades, novos caminhos, para se produzir o saber organizacional, discorrendo sobre o ensaio te?rico. Nada mais correto que ensaiar sobre o ensaio, apesar da tautologia. A relev?ncia desta proposta consiste em demonstrar que um ensaio te?rico original pode representar uma revitaliza??o da ci?ncia.The theoretical essay consists of a dimension few explored in the current organizational research field. This situation occurs due to the predominance of functionality orientation of research, which places as the central point the production of knowledge based on cause and effect relationships. This paper seeks to clarify other possibilities, new ways to produce organizational knowledge, discussing the theoretical essay. Nothing more correct than to assay about the essay, despite the tautology. The relevance of this proposal is to demonstrate that an original theoretical essay can represent a revitalization
Supersonic turbulence, filamentary accretion,and the rapid assembly of massive stars and disks
We present a detailed computational study of the assembly of protostellar
disks and massive stars in molecular clouds with supersonic turbulence. We
follow the evolution of large scale filamentary structures in a cluster-forming
clump down to protostellar length scales by means of very highly resolved, 3D
adaptive mesh refined (AMR) simulations, and show how accretion disks and
massive stars form in such environments. We find that an initially elongated
cloud core which has a slight spin from oblique shocks collapses first to a
filament and later develops a turbulent disk close to the center of the
filament. The continued large scale flow that shocks with the filament
maintains the high density and pressure within it. Material within the cooling
filament undergoes gravitational collapse and an outside-in assembly of a
massive protostar. Our simulations show that very high mass accretion rates of
up to 10^-2 Msol/yr and high, supersonic, infall velocities result from such
filamentary accretion. Accretion at these rates is higher by an order of
magnitude than those found in semi-analytic studies, and can quench the
radiation field of a growing massive young star.Our simulations include a
comprehensive set of the important chemical and radiative processes such as
cooling by molecular line emission, gas-dust interaction, and radiative
diffusion in the optical thick regime, as well as H2 formation and
dissociation. Therefore, we are able to probe, for the first time, the relevant
physical phenomena on all scales from those characterizing the clump down to
protostellar core.Comment: 35 pages, 17 figures, mnras style, accepted by MNRAS, a high
resolution version can be found at
http://www.ita.uni-heidelberg.de/~banerjee/TurbulentSF.pdf or
http://www.physics.mcmaster.ca/~banerjee/TurbulentSF.pd
Importance of the Initial Conditions for Star Formation - I. Cloud Evolution and Morphology
We present a detailed parameter study of collapsing turbulent cloud cores,
varying the initial density profile and the initial turbulent velocity field.
We systematically investigate the influence of different initial conditions on
the star formation process, mainly focusing on the fragmentation, the number of
formed stars, and the resulting mass distributions. Our study compares four
different density profiles (uniform, Bonnor-Ebert type, ,
and ), combined with six different supersonic turbulent
velocity fields (compressive, mixed, and solenoidal, initialised with two
different random seeds each) in three-dimensional simulations using the
adaptive-mesh refinement, hydrodynamics code FLASH. The simulations show that
density profiles with flat cores produce hundreds of low-mass stars, either
distributed throughout the entire cloud or found in subclusters, depending on
the initial turbulence. Concentrated density profiles always lead to the
formation of one high-mass star in the centre of the cloud and, if at all,
low-mass stars surrounding the central one. In uniform and Bonnor-Ebert type
density distributions, compressive initial turbulence leads to local collapse
about 25% earlier than solenoidal turbulence. However, central collapse in the
steep power-law profiles is too fast for the turbulence to have any significant
influence. We conclude that (I) the initial density profile and turbulence
mainly determine the cloud evolution and the formation of clusters, (II) the
initial mass function (IMF) is not universal for all setups, and (III) that
massive stars are much less likely to form in flat density distributions. The
IMFs obtained in the uniform and Bonnor-Ebert type density profiles are more
consistent with the observed IMF, but shifted to lower masses.Comment: 20 pages, MNRAS in pres
Nonlinear Evolution of Gravitational Fragmentation Regulated by Magnetic Fields and Ambipolar Diffusion
We present results from an extensive set of simulations of gravitational
fragmentation in the presence of magnetic fields and ambipolar diffusion. The
average fragmentation spacing in the nonlinear phase of evolution is in
excellent agreement with the prediction of linear perturbation theory. The time
scale for nonlinear growth and runaway of the first core is times
the calculated growth time \taugm of the eigenmode with minimum growth time,
when starting from a uniform background state with small-amplitude white-noise
perturbations. Subcritical and transcritical models typically evolve on a
significantly longer time scale than the supercritical models. Infall motions
in the nonlinear fully-developed contracting cores are subsonic on the core
scale in subcritical and transcritical clouds, but are somewhat supersonic in
supercritical clouds. Core mass distributions are sharply peaked with a steep
decline to large masses, consistent with the existence of a preferred mass
scale for each unique set of dimensionless free parameters. However, a sum
total of results for various initial mass-to-flux ratios yields a broad
distribution reminiscent of observed core mass distributions. Based on our
results, we conclude that fragmentation spacings, magnitude of infall motions,
core shapes, and, especially, the curvature of magnetic field morphology, may
serve as indirect observational means of determining a cloud's ambient
mass-to-flux ratio.Comment: v2, 13 figures, New Astronomy, animations can be obtained at
http://www.astro.uwo.ca/~basu/pb.ht
Reading Ronaldo: contingent whiteness in the football media
Ever since his introduction to the first-Â-team at Manchester United FC, Cristiano Ronaldo Dos Santos Aveiro has been recognised as one of the footballing worldâs most stand-Â-out football players. In turn, Ronaldo has drawn the attention of scholars working across a number of disciplines. While sports economists and sociologists of sport, amongst others, have contributed to a growing literature about Ronaldo and the social implications of his on and off-Â-field behaviour, few critical analyses have considered the racialised aspects of Ronaldoâs representations, or how audiences make sense of his racialised or ethnic identity. Using images of Ronaldo, which we presented to and discussed with self-Â-identified physically active white British men, we explore what it is representations and audience interpretations of Ronaldo reveal about the complexities of white male identity formation. We do this to understand better how white male identities can be read and interpreted through and in the context of football. Facilitated by our conception of contingent whiteness, we argue that white British menâs interpretations of Ronaldoâs whiteness are inextricably linked to discourses of âraceâ, masculinities and football
Risk and clinical-outcome indicators of delirium in an emergency department intermediate care unit (EDIMCU) : an observational prospective study
We are thankful to the staff at the EDIMCU of Hospital de Braga.Background
Identification of delirium in emergency departments (ED) is often underestimated; within EDs, studies on delirium assessment and relation with patient outcome in Intermediate Care Units (IMCU) appear missing in European hospital settings. Here we aimed to determine delirium prevalence in an EDIMCU (Hospital de Braga, Braga, Portugal) and assessed routine biochemical parameters that might be delirium indicators.
Methods
The study was prospective and observational. Sedation level was assessed via the Richmond Agitation-Sedation Scale and delirium status by the Confusion Assessment Method for the ICU. Information collected included age and gender, admission type, Charlson Comorbidity Index combined condition score (Charlson score), systemic inflammatory response syndrome criteria (SIRS), biochemical parameters (blood concentration of urea nitrogen, creatinine, hemoglobin, sodium and potassium, arterial blood gases, and other parameters as needed depending on clinical diagnosis) and EDIMCU length of stay (LOS). Statistical analyses were performed as appropriate to determine if baseline features differed between the âDeliriumâ and âNo Deliriumâ groups. Multivariate logistic regression was performed to assess the effect of delirium on the 1-month outcome.
Results
Inclusion and exclusion criteria were met in 283 patients; 238 were evaluated at 1-month for outcome follow-up after EDIMCU discharge (âgoodâ recovery without complications requiring hospitalization or institutionalization; âpoorâ institutionalization in permanent care-units/assisted-living or death). Delirium was diagnosed in 20.1% patients and was significantly associated with longer EDIMCU LOS. At admission, Delirium patients were significantly older and had significantly higher blood urea, creatinine and osmolarity levels and significantly lower hemoglobin levels, when compared with No Delirium patients. Delirium was an independent predictor of increased EDIMCU LOS (odds ratio 3.65, 95% CI 1.97-6.75) and poor outcome at 1-month after discharge (odds ratio 3.51, CI 1.84-6.70), adjusted for age, gender, admission type, presence of SIRS criteria, Charlson score and osmolarity at admission.
Conclusions
In an EDIMCU setting, delirium was associated with longer LOS and poor outcome at1-month post-discharge. Altogether, findings support the need for delirium screening and management in emergency settings.NCS is supported by the post-doctoral fellowship UMINHO/BPD/013/2011 by the European Commission (FP7) âSwitchBoxâ Project (Contract HEALTH-F2-2010-259772)
Asteroseismology and Interferometry
Asteroseismology provides us with a unique opportunity to improve our
understanding of stellar structure and evolution. Recent developments,
including the first systematic studies of solar-like pulsators, have boosted
the impact of this field of research within Astrophysics and have led to a
significant increase in the size of the research community. In the present
paper we start by reviewing the basic observational and theoretical properties
of classical and solar-like pulsators and present results from some of the most
recent and outstanding studies of these stars. We centre our review on those
classes of pulsators for which interferometric studies are expected to provide
a significant input. We discuss current limitations to asteroseismic studies,
including difficulties in mode identification and in the accurate determination
of global parameters of pulsating stars, and, after a brief review of those
aspects of interferometry that are most relevant in this context, anticipate
how interferometric observations may contribute to overcome these limitations.
Moreover, we present results of recent pilot studies of pulsating stars
involving both asteroseismic and interferometric constraints and look into the
future, summarizing ongoing efforts concerning the development of future
instruments and satellite missions which are expected to have an impact in this
field of research.Comment: Version as published in The Astronomy and Astrophysics Review, Volume
14, Issue 3-4, pp. 217-36
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