185 research outputs found
Breeding Bird Surveys at Alexandra Fiord, Ellesmere Island, Nunavut (1980â2008)
Long-term monitoring of bird populations in the Arctic is of considerable interest as this area is experiencing rapid climate warming; however, multi-decadal studies in the Canadian High Arctic are rare. Over five summers between 1980 and 2008, we conducted breeding bird surveys by walking transects and mapping territories in a periglacial lowland on east-central Ellesmere Island, Nunavut. In all survey years, snow bunting (Plectrophenax nivalis), Lapland longspur (Calcarius lapponicus), and Baird's sandpiper (Calidris bairdii) were the most abundant species. Over the study period, the assemblage of breeding bird species appears to have changed little, except for an increase in Lapland longspur. In the summer of 2008, we also compared two techniques for censusing territories. We found that spot-mapping, a simple and cost-effective method, produced similar results to the more labour-intensive active-flushing. Spot-mapping is therefore suitable for conducting bird surveys in northern locations where the vegetation is short, the terrain is flat, and the visibility is extensive. In the coming years, it will be important to continue monitoring Arctic birds to determine how climate change is affecting their breeding populations.La surveillance Ă long terme des populations d'oiseaux de l'Arctique revĂȘt un intĂ©rĂȘt considĂ©rable Ă la lumiĂšre du changement climatique rapide que connaĂźt cette rĂ©gion. Cela dit, il faut remarquer que peu d'Ă©tudes Ă©chelonnĂ©es sur plusieurs dĂ©cennies ont Ă©tĂ© rĂ©alisĂ©es dans l'ExtrĂȘme-Arctique canadien. Au cours de cinq Ă©tĂ©s rĂ©partis entre 1980 et 2008, nous avons effectuĂ© le dĂ©nombrement d'oiseaux nicheurs en traversant des transects et en cartographiant des territoires situĂ©s sur les basses terres pĂ©riglaciaires de l'Ăźle d'Ellesmere, au Nunavut. Au cours de toutes les annĂ©es visĂ©es par le dĂ©nombrement, le bruant des neiges (Plectrophenax nivalis), le bruant lapon (Calcarius lapponicus) et le bĂ©casseau de Baird (Calidris bairdii) se sont avĂ©rĂ©s les espĂšces les plus abondantes. Au cours de la pĂ©riode visĂ©e par l'Ă©tude, l'assemblage d'espĂšces d'oiseaux nicheurs semble avoir peu changĂ©, sauf pour ce qui est d'une augmentation de bruants lapons. Ă l'Ă©tĂ© 2008, nous avons Ă©galement comparĂ© deux techniques de recensement des territoires. Nous avons effectivement constatĂ© que la mĂ©thode des plans quadrillĂ©s, une mĂ©thode simple et abordable, donnait des rĂ©sultats semblables Ă la mĂ©thode de dispersion active qui demande beaucoup plus de travail. Par consĂ©quent, la mĂ©thode des plans quadrillĂ©s convient bien Ă la rĂ©alisation de recensements d'oiseaux dans les emplacements nordiques oĂč la vĂ©gĂ©tation est courte, oĂč le terrain est plat et oĂč la visibilitĂ© est vaste. Au cours des annĂ©es Ă venir, il sera important de continuer Ă surveiller les oiseaux de l'Arctique afin de dĂ©terminer quelles sont les incidences du changement climatique sur les populations d'oiseaux nicheurs
Accurate prediction of gene expression by integration of DNA sequence statistics with detailed modeling of transcription regulation
Gene regulation involves a hierarchy of events that extend from specific
protein-DNA interactions to the combinatorial assembly of nucleoprotein
complexes. The effects of DNA sequence on these processes have typically been
studied based either on its quantitative connection with single-domain binding
free energies or on empirical rules that combine different DNA motifs to
predict gene expression trends on a genomic scale. The middle-point approach
that quantitatively bridges these two extremes, however, remains largely
unexplored. Here, we provide an integrated approach to accurately predict gene
expression from statistical sequence information in combination with detailed
biophysical modeling of transcription regulation by multidomain binding on
multiple DNA sites. For the regulation of the prototypical lac operon, this
approach predicts within 0.3-fold accuracy transcriptional activity over a
10,000-fold range from DNA sequence statistics for different intracellular
conditions.Comment: 15 pages, 5 figure
PTSD, psychological morbidity and marital dissatisfaction in colonial war veterans
Background: Forty years after Colonial War, veterans still show psychological disturbances affecting their marital and sexual satisfaction.Aims: This study analyzed the relationships between Post-Traumatic Stress Disorder (PTSD), number of PTSD symptoms and symptom clusters, psychological morbidity, marital dissatisfaction and sexual dissatisfaction; the variables that contributed to marital dissatisfaction and the mediator role of marital dissatisfaction and sexual dissatisfaction, in a sample of colonial War Veterans.Method: The sample included 138 Portuguese war veterans who answered Index of Marital Satisfaction; Index of Sexual Satisfaction; Beck Depression Inventory; State Trait Anxiety Inventory; Post-Traumatic Stress Disorder Scale.Results: PTSD, number of PTSD symptoms and symptom clusters were associated with psychological morbidity, marital and sexual dissatisfaction. Age, depression symptoms and sexual dissatisfaction contributed to marital dissatisfaction and the model explained 55% of the variance. Marital dissatisfaction mediated the relationship between depression symptoms and sexual dissatisfaction, as well as between number of PTSD symptoms and sexual dissatisfaction.Conclusions: Health professionals need to take into consideration the veteran's marital and sexual relationship in clinical routine consultations. As such, treating the veteran in the couple' context seems warranted.Bayer Portuguesa (B02/06
Deceleration and trapping of heavy diatomic molecules using a ring-decelerator
We present an analysis of the deceleration and trapping of heavy diatomic
molecules in low-field seeking states by a moving electric potential. This
moving potential is created by a 'ring-decelerator', which consists of a series
of ring-shaped electrodes to which oscillating high voltages are applied.
Particle trajectory simulations have been used to analyze the deceleration and
trapping efficiency for a group of molecules that is of special interest for
precision measurements of fundamental discrete symmetries. For the typical case
of the SrF molecule in the (N,M) = (2, 0) state, the ring-decelerator is shown
to outperform traditional and alternate-gradient Stark decelerators by at least
an order of magnitude. If further cooled by a stage of laser cooling, the
decelerated molecules allow for a sensitivity gain in a parity violation
measurement, compared to a cryogenic molecular beam experiment, of almost two
orders of magnitude
Multilevel Deconstruction of the In Vivo Behavior of Looped DNA-Protein Complexes
Protein-DNA complexes with loops play a fundamental role in a wide variety of
cellular processes, ranging from the regulation of DNA transcription to
telomere maintenance. As ubiquitous as they are, their precise in vivo
properties and their integration into the cellular function still remain
largely unexplored. Here, we present a multilevel approach that efficiently
connects in both directions molecular properties with cell physiology and use
it to characterize the molecular properties of the looped DNA-lac repressor
complex while functioning in vivo. The properties we uncover include the
presence of two representative conformations of the complex, the stabilization
of one conformation by DNA architectural proteins, and precise values of the
underlying twisting elastic constants and bending free energies. Incorporation
of all this molecular information into gene-regulation models reveals an
unprecedented versatility of looped DNA-protein complexes at shaping the
properties of gene expression.Comment: Open Access article available at
http://www.plosone.org/article/fetchArticle.action?articleURI=info%3Adoi%2F10.1371%2Fjournal.pone.000035
Quantum optics in the phase space - A tutorial on Gaussian states
In this tutorial, we introduce the basic concepts and mathematical tools
needed for phase-space description of a very common class of states, whose
phase properties are described by Gaussian Wigner functions: the Gaussian
states. In particular, we address their manipulation, evolution and
characterization in view of their application to quantum information.Comment: Tutorial. 23 pages, 1 figure. Updated version accepted for
publication in EPJ - ST devoted to the memory of Federico Casagrand
A multi-species synthesis of physiological mechanisms in drought-induced tree mortality
Widespread tree mortality associated with drought 92 has been observed on all forested continents, and global change is expected to exacerbate vegetation vulnerability. Forest mortality has implications for future biosphere-atmosphere interactions of carbon, water, and energy balance, and is poorly represented in dynamic vegetation models. Reducing uncertainty requires improved mortality projections founded on robust physiological processes. However, the proposed mechanisms of drought-induced mortality, including hydraulic failure and carbon starvation, are unresolved. A growing number of empirical studies have investigated these mechanisms, but data have not been consistently analyzed across species and biomes using a standardized physiological framework. Here we show that xylem hydraulic failure was ubiquitous across multiple tree taxa at drought induced mortality. All species assessed had 60% or higher loss of xylem hydraulic conductivity, consistent with proposed theoretical and modelled survival thresholds. We found diverse responses in non-structural carbohydrate reserves at mortality, indicating that evidence supporting carbon starvation was not universal. Reduced non-structural carbohydrates were more common for gymnosperms than angiosperms, associated with xylem hydraulic vulnerability, and may have a role in reducing hydraulic function. Our finding that hydraulic failure at drought-induced mortality was persistent across species indicates that substantial improvement in vegetation modelling can be achieved using thresholds in hydraulic function
A multi-species synthesis of physiological mechanisms in drought-induced tree mortality
Widespread tree mortality associated with drought 92 has been observed on all forested continents, and global change is expected to exacerbate vegetation vulnerability. Forest mortality has implications for future biosphere-atmosphere interactions of carbon, water, and energy balance, and is poorly represented in dynamic vegetation models. Reducing uncertainty requires improved mortality projections founded on robust physiological processes. However, the proposed mechanisms of drought-induced mortality, including hydraulic failure and carbon starvation, are unresolved. A growing number of empirical studies have investigated these mechanisms, but data have not been consistently analyzed across species and biomes using a standardized physiological framework. Here we show that xylem hydraulic failure was ubiquitous across multiple tree taxa at drought induced mortality. All species assessed had 60% or higher loss of xylem hydraulic conductivity, consistent with proposed theoretical and modelled survival thresholds. We found diverse responses in non-structural carbohydrate reserves at mortality, indicating that evidence supporting carbon starvation was not universal. Reduced non-structural carbohydrates were more common for gymnosperms than angiosperms, associated with xylem hydraulic vulnerability, and may have a role in reducing hydraulic function. Our finding that hydraulic failure at drought-induced mortality was persistent across species indicates that substantial improvement in vegetation modelling can be achieved using thresholds in hydraulic function
Palaeoenvironmental control on distribution of crinoids in the Bathonian (Middle Jurassic) of England and France
Bulk sampling of a number of different marine and marginal marine lithofacies in the British Bathonian has allowed us to assess the palaeoenvironmental distribution of crinoids for the first time. Although remains are largely fragmentary, many species have been identified by comparison with articulated specimens from elsewhere, whilst the large and unbiased sample sizes allowed assessment of relative proportions of different taxa. Results indicate that distribution of crinoids well corresponds to particular facies. Ossicles of Chariocrinus and Balanocrinus dominate in deeper-water and lower-energy facies,with the former extending further into shallower-water facies than the latter. Isocrinus dominates in shallower water carbonate facies, accompanied by rarer comatulids, and was also present in the more marine parts of lagoons. Pentacrinites remains are abundant in very high-energy oolite shoal lithofacies. The presence of millericrinids within one, partly allochthonous lithofacies suggests the presence of an otherwise unknown hard substrate from which they have been transported. These results are compared to crinoid assemblages from other Mesozoic localities, and it is evident that the same morphological ad-aptations are present within crinoids from similar lithofacies throughout the Jurassic and Early Cretaceous
COVAD survey 2 long-term outcomes: unmet need and protocol
Vaccine hesitancy is considered a major barrier to achieving herd immunity against COVID-19. While multiple alternative and synergistic approaches including heterologous vaccination, booster doses, and antiviral drugs have been developed, equitable vaccine uptake remains the foremost strategy to manage pandemic. Although none of the currently approved vaccines are live-attenuated, several reports of disease flares, waning protection, and acute-onset syndromes have emerged as short-term adverse events after vaccination. Hence, scientific literature falls short when discussing potential long-term effects in vulnerable cohorts. The COVAD-2 survey follows on from the baseline COVAD-1 survey with the aim to collect patient-reported data on the long-term safety and tolerability of COVID-19 vaccines in immune modulation. The e-survey has been extensively pilot-tested and validated with translations into multiple languages. Anticipated results will help improve vaccination efforts and reduce the imminent risks of COVID-19 infection, especially in understudied vulnerable groups
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