433 research outputs found
Linking coastal and seafloor morphological features along the eastern side of the Maltese archipelago
The integration of detailed geomorphological information from the present
subaerial exposures of the Maltese archipelago, with morphobathymetric data obtained
from the adjacent continental margin may serve in understanding processes active in
shaping the archipelago since the Last Glacial Maximum. In perspective, this appears also
to be of fundamental importance to better define the kinematics of active gravitational
processes occurring along the coastlines. Preliminary results reveal the existence of
submerged morphologies comparable to subaerial analogous. A case in point is circular
depressions at shallow depth interpreted as inundated former karst features like sinkholes
on-land. This is probably the case also of fractured plateaus surrounded by detached blocks
identified offshore, which are comparable to terrestrial landforms formed by lateral
spreading. Other relevant features identified on the continental margin and easily
correlatable with morphologies on land include meandering river valleys.peer-reviewe
Creation and manipulation of entanglement in spin chains far from equilibrium
We investigate creation, manipulation, and steering of entanglement in spin
chains from the viewpoint of quantum communication between distant parties. We
demonstrate how global parametric driving of the spin-spin coupling and/or
local time-dependent Zeeman fields produce a large amount of entanglement
between the first and the last spin of the chain. This occurs whenever the
driving frequency meets a resonance condition, identified as "entanglement
resonance". Our approach marks a promising step towards an efficient quantum
state transfer or teleportation in solid state system. Following the reasoning
of Zueco et al. [1], we propose generation and routing of multipartite
entangled states by use of symmetric tree-like structures of spin chains.
Furthermore, we study the effect of decoherence on the resulting spin
entanglement between the corresponding terminal spins.Comment: 10 pages, 8 figure
The Physical Basis for Long-lived Electronic Coherence in Photosynthetic Light Harvesting Systems
The physical basis for observed long-lived electronic coherence in
photosynthetic light-harvesting systems is identified using an analytically
soluble model. Three physical features are found to be responsible for their
long coherence lifetimes: i) the small energy gap between excitonic states, ii)
the small ratio of the energy gap to the coupling between excitonic states, and
iii) the fact that the molecular characteristics place the system in an
effective low temperature regime, even at ambient conditions. Using this
approach, we obtain decoherence times for a dimer model with FMO parameters of
160 fs at 77 K and 80 fs at 277 K. As such, significant
oscillations are found to persist for 600 fs and 300 fs, respectively, in
accord with the experiment and with previous computations. Similar good
agreement is found for PC645 at room temperature, with oscillations persisting
for 400 fs. The analytic expressions obtained provide direct insight into the
parameter dependence of the decoherence time scales.Comment: 5 figures; J. Phys. Chem. Lett. (2011
Propagation properties and limitations on the attainable entanglement in a driven harmonic chain
The limitations on the production and profitability of entanglement in a
harmonic chain under strong driving are considered. We report on the limits of
attainable entanglement for a given set of squeezings of the eigenmodes,
showing that the higher the entanglement the more oscillatory and thus less
easy to profit from. We also comment on propagation properties of entanglement,
discussing the role of fast rotating terms and illustrating several issues with
the example of a sudden switch of the coupling.Comment: 9 pages, 5 figure
Activation of Type 1 Cannabinoid Receptor (CB1R) promotes neurogenesis in murine subventricular zone cell cultures
The endocannabinoid system has been implicated in the modulation of adult neurogenesis. Here, we describe the effect of type 1 cannabinoid receptor (CB1R) activation on self-renewal, proliferation and neuronal differentiation in mouse neonatal subventricular zone (SVZ) stem/progenitor cell cultures. Expression of CB1R was detected in SVZ-derived immature cells (Nestin-positive), neurons and astrocytes. Stimulation of the CB1R by (R)-(+)-Methanandamide (R-m-AEA) increased self-renewal of SVZ cells, as assessed by counting the number of secondary neurospheres and the number of Sox2+/+ cell pairs, an effect blocked by Notch pathway inhibition. Moreover, R-m-AEA treatment for 48 h, increased proliferation as assessed by BrdU incorporation assay, an effect mediated by activation of MAPK-ERK and AKT pathways. Surprisingly, stimulation of CB1R by R-m-AEA also promoted neuronal differentiation (without affecting glial differentiation), at 7 days, as shown by counting the number of NeuN-positive neurons in the cultures. Moreover, by monitoring intracellular calcium concentrations ([Ca2+](i)) in single cells following KCl and histamine stimuli, a method that allows the functional evaluation of neuronal differentiation, we observed an increase in neuronal-like cells. This proneurogenic effect was blocked when SVZ cells were co-incubated with R-m-AEA and the CB1R antagonist AM 251, for 7 days, thus indicating that this effect involves CB1R activation. In accordance with an effect on neuronal differentiation and maturation, R-m-AEA also increased neurite growth, as evaluated by quantifying and measuring the number of MAP2-positive processes. Taken together, these results demonstrate that CB1R activation induces proliferation, self-renewal and neuronal differentiation from mouse neonatal SVZ cell cultures.Fundacao para a Ciencia e a Tecnologia - Portugal [POCTI/SAU-NEU/68465/2006, PTDC/SAU-NEU/104415/2008, PTDC/SAU-NEU/101783/2008, POCTI/SAU-NEU/110838/2009]; Fundacao Calouste Gulbenkian [96542]; Fundacao para a Ciencia e Tecnologiainfo:eu-repo/semantics/publishedVersio
Optimal nonequilibrium entanglement of nanomechanical oscillators
We investigate nonequilibrium entanglement generation in a chain of harmonic
oscillators with time-dependent linear coupling. We use optimal control theory
to determine the coupling modulation that leads to maximum logarithmic
negativity for a pair of opposite oscillators and show that it corresponds to a
synchronization of the eigenmodes of the chain. We further analytically relate
the maximum attainable entanglement to the irreversible work done to produce
it, thus bridging nonequilibrium entanglement production and nonequilibrium
thermodynamics.Comment: 4 pages, 3 figure
Cause of Death and Predictors of All-Cause Mortality in Anticoagulated Patients With Nonvalvular Atrial Fibrillation : Data From ROCKET AF
M. Kaste on työryhmän ROCKET AF Steering Comm jäsen.Background-Atrial fibrillation is associated with higher mortality. Identification of causes of death and contemporary risk factors for all-cause mortality may guide interventions. Methods and Results-In the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF) study, patients with nonvalvular atrial fibrillation were randomized to rivaroxaban or dose-adjusted warfarin. Cox proportional hazards regression with backward elimination identified factors at randomization that were independently associated with all-cause mortality in the 14 171 participants in the intention-to-treat population. The median age was 73 years, and the mean CHADS(2) score was 3.5. Over 1.9 years of median follow-up, 1214 (8.6%) patients died. Kaplan-Meier mortality rates were 4.2% at 1 year and 8.9% at 2 years. The majority of classified deaths (1081) were cardiovascular (72%), whereas only 6% were nonhemorrhagic stroke or systemic embolism. No significant difference in all-cause mortality was observed between the rivaroxaban and warfarin arms (P=0.15). Heart failure (hazard ratio 1.51, 95% CI 1.33-1.70, P= 75 years (hazard ratio 1.69, 95% CI 1.51-1.90, P Conclusions-In a large population of patients anticoagulated for nonvalvular atrial fibrillation, approximate to 7 in 10 deaths were cardiovascular, whereasPeer reviewe
Interplay between n-3 and n-6 long-chain polyunsaturated fatty acids and the endocannabinoid system in brain protection and repair.
The brain is enriched in arachidonic acid (ARA) and docosahexaenoic acid (DHA), long-chain polyunsaturated fatty acids (LCPUFA) of the n-6 and n-3 series, respectively. Both are essential for optimal brain development and function. Dietary enrichment with DHA and other long-chain n-3 PUFA, such as eicosapentaenoic acid (EPA) have shown beneficial effects on learning and memory, neuroinflammatory processes and synaptic plasticity and neurogenesis. ARA, DHA and EPA are precursors to a diverse repertoire of bioactive lipid mediators, including endocannabinoids. The endocannabinoid system comprises cannabinoid receptors, their endogenous ligands, the endocannabinoids, and their biosynthetic and degradation enzymes. Anandamide (AEA) and 2-archidonoylglycerol (2-AG) are the most widely studied endocannabinoids, and are both derived from phospholipid-bound ARA. The endocannabinoid system also has well established roles in neuroinflammation, synaptic plasticity and neurogenesis, suggesting an overlap in the neuroprotective effects observed with these different classes of lipids. Indeed, growing evidence suggests a complex interplay between n-3 and n-6 LCPUFA and the endocannabinoid system. For example, long-term DHA and EPA supplementation reduces AEA and 2-AG levels, with reciprocal increases in levels of the analogous endocannabinoid-like DHA and EPA-derived molecules. This review summarises current evidence of this interplay and discusses the therapeutic potential for brain protection and repair
Educação Física na Educação Infantil na rede pública de ensino da Grande Vitória/ES: análise das propostas curriculares
This study maps and analyzes the curriculum proposals for early childhood education in four municipalities in Greater Vitória/ES. It aims to understand how Physical Education is interpreted and affirmed in these documents. Methodologically, the investigation was guided by documentary analysis. As a result, it identifies that, in addition to sharing conceptions of childhood and early childhood education of nationwide curricular references, the documents of the researched municipal networks elaborate syntheses and unique themes about Physical Education as a curricular component. Although they represent an advance in the debate on the role of Physical Education in early childhood education, when compared to national curriculum documents, there is no consensus on how this should happen in the analyzed proposals.Este estudio mapea y analiza las propuestas curriculares para la educación infantil en cuatro municipios de Gran Vitória/ES. Su objetivo es comprender las formas que la Educación Física se interpreta y afirma en estos documentos. Metodológicamente, la investigación se guió por el análisis documental. Como resultado, identifica que, además de compartir concepciones de educación infantil y primera infancia de referencias curriculares a nivel nacional, los documentos de las redes municipales investigadas elaboran síntesis y temáticas singulares sobre la Educación Física como componente curricular. A pesar de representar un avance en el debate sobre el papel de la Educación Física en la educación infantil, al compararlo con los documentos curriculares nacionales, no existe consenso sobre cómo debería ocurrir en las propuestas analizadas.Este estudo mapeia e analisa as propostas curriculares para a educação infantil em quatro municípios da Grande Vitória/ES. Tem como objetivo compreender os modos pelos quais a Educação Física é interpretada e afirmada nesses documentos. Metodologicamente, a investigação foi guiada pela análise documental. Como resultados, identifica que, além de compartilharem concepções de infância e de educação infantil dos referenciais curriculares de âmbito nacional, os documentos das redes municipais pesquisadas elaboram sínteses e tematizações singulares acerca da Educação Física como componente curricular. Apesar de representarem um avanço no debate sobre o papel da Educação Física na educação infantil, quando comparados com os documentos curriculares nacionais, não há um consenso sobre a forma como isso deve acontecer nas propostas analisadas
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