579 research outputs found
Atrial Fibrillation in Eight New World Camelids.
BackgroundThere is limited information on the incidence of clinical signs, concurrent illness and treatment options for atrial fibrillation (AF) in New World Camelids (NWC).ObjectiveDescribe clinical signs and outcome of AF in NWC.AnimalsEight New World Camelids admitted with AF.MethodsA retrospective observational study of camelids diagnosed with AF based on characteristic findings on electrocardiogram (ECG).ResultsAll animals had an irregularly irregular heart rhythm detected on physical examination and 4 cases had obtunded mentation on admission. Three camelids were diagnosed with AF secondary to oleander intoxication, 3 animals had underlying cardiovascular disease, 1 was diagnosed with lone AF and 1 had AF diagnosed on examination for a urethral obstruction. Five of eight animals survived to discharge and nonsurvivors consisted of animals which died or were euthanized as a result of cardiovascular disease (2/8) or extra-cardiac disease unrelated to the AF (1/8).Conclusions and clinical importanceAtrial fibrillation occurs in NWC in association with cardiovascular disease, extra-cardiac disease or as lone AF. Amiodarone and transthoracic cardioversion were attempted in one llama with lone AF, but were unsuccessful. Atrial fibrillation was recorded in 0.1% of admissions
Surface electrons at plasma walls
In this chapter we introduce a microscopic modelling of the surplus electrons
on the plasma wall which complements the classical description of the plasma
sheath. First we introduce a model for the electron surface layer to study the
quasistationary electron distribution and the potential at an unbiased plasma
wall. Then we calculate sticking coefficients and desorption times for electron
trapping in the image states. Finally we study how surplus electrons affect
light scattering and how charge signatures offer the possibility of a novel
charge measurement for dust grains.Comment: To appear in Complex Plasmas: Scientific Challenges and Technological
Opportunities, Editors: M. Bonitz, K. Becker, J. Lopez and H. Thomse
Continuous heating of a giant X-ray flare on Algol
Giant flares can release large amounts of energy within a few days: X-ray
emission alone can be up to ten percent of the star's bolometric luminosity.
These flares exceed the luminosities of the largest solar flares by many orders
of magnitude, which suggests that the underlying physical mechanisms supplying
the energy are different from those on the Sun. Magnetic coupling between the
components in a binary system or between a young star and an accretion disk has
been proposed as a prerequisite for giant flares. Here we report X-ray
observations of a giant flare on Algol B, a giant star in an eclipsing binary
system. We observed a total X-ray eclipse of the flare, which demonstrates that
the plasma was confined to Algol B, and reached a maximum height of 0.6 stellar
radii above its surface. The flare occurred around the south pole of Algol B,
and energy must have been released continously throughout its life. We conclude
that a specific extrastellar environment is not required for the presence of a
flare, and that the processes at work are therefore similar to those on the
Sun.Comment: Nature, Sept. 2 199
Numerical properties of staggered quarks with a taste-dependent mass term
The numerical properties of staggered Dirac operators with a taste-dependent
mass term proposed by Adams [1,2] and by Hoelbling [3] are compared with those
of ordinary staggered and Wilson Dirac operators. In the free limit and on
(quenched) interacting configurations, we consider their topological
properties, their spectrum, and the resulting pion mass. Although we also
consider the spectral structure, topological properties, locality, and
computational cost of an overlap operator with a staggered kernel, we call
attention to the possibility of using the Adams and Hoelbling operators without
the overlap construction. In particular, the Hoelbling operator could be used
to simulate two degenerate flavors without additive mass renormalization, and
thus without fine-tuning in the chiral limit.Comment: 14 pages, 9 figures. V2: published version; important note added
regarding Hoelbling fermions, otherwise minor change
The BDNF Val66Met polymorphism moderates the relationship between cognitive reserve and executive function
The concept of cognitive reserve (CR) has been proposed to account for observed discrepancies between pathology and its clinical manifestation due to underlying differences in brain structure and function. In 433 healthy older adults participating in the Tasmanian Healthy Brain Project, we investigated whether common polymorphic variations in apolipoprotein E (APOE) or brain-derived neurotrophic factor (BDNF) influenced the association between CR contributors and cognitive function in older adults. We show that BDNF Val66Met moderates the association between CR and executive function. CR accounted for 8.5% of the variance in executive function in BDNF Val homozygotes, but CR was a nonsignificant predictor in BDNF Met carriers. APOE polymorphisms were not linked to the influence of CR on cognitive function. This result implicates BDNF in having an important role in capacity for building or accessing CR
Following 411 Cochrane Protocols to Completion: A Retrospective Cohort Study
Cochrane reviews are regarded as being scientifically rigorous and are increasingly used by a variety of stakeholders. However, factors predicting the publication of Cochrane reviews have never been reported. This is important because if a higher proportion of Cochrane protocols with certain characteristics (e.g., funding) are being published, this may lead to inaccurate decisions. We examined the frequency of published and unpublished Cochrane reviews and protocol factors that predict the publication of Cochrane reviews.Retrospective cohort study of Cochrane protocols published in 2000 (Issues 2 to 4) and 2001 (Issue 1). The publication status of these reviews was followed up to Issue 1, 2008 in The Cochrane Library. Survival analysis of the time from protocol publication to the first review publication and protocol factors predicting the time to publication was conducted. There were 411 new Cochrane protocols in the cohort. After excluding 39; 71/372 (19.1%) were unpublished and 301/372 (80.9%) were published as full Cochrane reviews at the time of study analysis (January 2008). The median time to publication was 2.4 years (range: 0.15 to 8.96). Multivariate analyses revealed that shorter time to publication was associated with the review subsequently being updated (hazard ratio, HR: 1.80 [95% confidence interval, CI: 1.39 to 2.33 years]) and longer time to publication was associated with the review having two published protocols, indicating changes to the review plan (HR: 0.33 [95% CI: 0.12 to 0.90 years]).Only about 80% Cochrane protocols were published as full reviews after over 8 years of follow-up. The median time to publication was 2.4 years and some reviews took much longer. Strategies to decrease time to publication should be considered, such as streamlining the review process, increased support for authors when protocol amendments occur, and better infrastructure for updating Cochrane reviews
Global Development and Climate Change: A Game Theory Approach
The increasing concern with climate change is one of the main issues of our time, and thus we aim to theoretically and mathematically analyse its causes. However our approach follows a different stream of thought, presenting the reasoning and decision-making processes between technical and moral solutions. We have resorted to game theory models in order to demonstrate cooperative and non-cooperative scenarios, ranging from the traditional to the evolutionary within game theory. In doing so we are able to glimpse the development of modern society and a paradigm shift regarding human control over nature and to what extent it is harmful to the sustainability of our environment and the survival of future generations. Merging different fields of knowledge, we present a theoretical-philosophical approach, combined with empirical-mathematical solutions taking into account the agent-based behaviour guided blindly by instrumental rationality
Revisiting symmetries of lattice fermions via spin-flavor representation
Employing the spin-flavor representation, we investigate the structures of
the doubler-mixing symmetries and the mechanisms of their spontaneous breakdown
in four types of lattice fermion formulation. We first revisit the
U(4)\timesU(4)A symmetries of the naive fermion with the vanishing bare mass
m, and re-express them in terms of the spin-flavor representation. We apply the
same method to the Wilson fermion, which possesses only the U(1) vector
symmetry for general values of m. For a special value of m, however, there
emerges an additional U(1) symmetry to be broken by pion condensation. We also
explore two types of minimally doubled fermion, and discover a similar kind of
symmetry enhancement and its spontaneous breakdown.Comment: 25 pages, no figure;v2 typos corrected;v3 Sec.2 is shortened. To
appear in JHE
Distinct Steps of Neural Induction Revealed by Asterix, Obelix and TrkC, Genes Induced by Different Signals from the Organizer
The amniote organizer (Hensen's node) can induce a complete nervous system when grafted into a peripheral region of a host embryo. Although BMP inhibition has been implicated in neural induction, non-neural cells cannot respond to BMP antagonists unless previously exposed to a node graft for at least 5 hours before BMP inhibitors. To define signals and responses during the first 5 hours of node signals, a differential screen was conducted. Here we describe three early response genes: two of them, Asterix and Obelix, encode previously undescribed proteins of unknown function but Obelix appears to be a nuclear RNA-binding protein. The third is TrkC, a neurotrophin receptor. All three genes are induced by a node graft within 4–5 hours but they differ in the extent to which they are inducible by FGF: FGF is both necessary and sufficient to induce Asterix, sufficient but not necessary to induce Obelix and neither sufficient nor necessary for induction of TrkC. These genes are also not induced by retinoic acid, Noggin, Chordin, Dkk1, Cerberus, HGF/SF, Somatostatin or ionomycin-mediated Calcium entry. Comparison of the expression and regulation of these genes with other early neural markers reveals three distinct “epochs”, or temporal waves, of gene expression accompanying neural induction by a grafted organizer, which are mirrored by specific stages of normal neural plate development. The results are consistent with neural induction being a cascade of responses elicited by different signals, culminating in the formation of a patterned nervous system
Introduction to the Conceptualisation of Environmental Citizenship for Twenty-First-Century Education
The EU’s growth strategy (Europe 2020) and the European vision for green, circular and low-carbon economy in line with the EU 2050 (EU-roadmap 2050) give par- ticular attention to citizens’ participation and engagement and therefore to Environmental Citizenship. Environmental Citizenship has been an influential con- cept in many different arenas such as economy, policy, philosophy, corporation management and marketing, which could also be better exploited and established in the field of education. Environmental Citizenship is recognized as an important aspect in addressing global environmental problems such as climate change (Stern 2011; Ockwell et al. 2009) whilst providing support to pro-environmental organisa- tions and individuals, contributing also to public pressure for political action (sign- ing petitions, writing to politicians and newspapers). Many varied definitions of Environmental Citizenship can be found within the literature. Some of them are quite similar, and important overlaps can be observed; however, others can be quite different with contradictions in their philosophy and approach. According to Dobson (2010), Environmental Citizenship refers to pro-environmental behaviour, in public and in private, driven by a belief in fairness of the distribution of environmental goods, in participation and in the co-creation of sustainability policy. It is about the active participation of citizens in moving towards sustainability. Education and especially environmental discourses in science education have a lot to contribute in adopting and promoting Environmental Citizenship. However, the conceptualisation of Environmental Citizenship in educational context remains an imperative need. The under-explored (until now) potential for pro-environmental behaviour change through Environmental Citizenship should be further emphasised (Dobson 2010) and can contribute greatly to a more sustainable world.info:eu-repo/semantics/publishedVersio
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