2,453 research outputs found
Searching for galactic sources in the Swift GRB catalog
Since the early 1990s Gamma Ray Bursts have been accepted to be of
extra-galactic origin due to the isotropic distribution observed by BATSE and
the redshifts observed via absorption line spectroscopy. Nevertheless, upon
further examination at least one case turned out to be of galactic origin. This
particular event presented a Fast Rise, Exponential Decay (FRED) structure
which leads us to believe that other FRED sources might also be Galactic. This
study was set out to estimate the most probable degree of contamination by
galactic sources that certain samples of FREDs have. In order to quantify the
degree of anisotropy the average dipolar and quadripolar moments of each sample
of GRBs with respect to the galactic plane were calculated. This was then
compared to the probability distribution of simulated samples comprised of a
combination of isotropically generated sources and galactic sources. We observe
that the dipolar and quadripolar moments of the selected subsamples of FREDs
are found more than two standard deviations outside those of random
isotropically generated samples.The most probable degree of contamination by
galactic sources for the FRED GRBs of the Swift catalog detected until February
2011 that do not have a known redshift is about 21 out of 77 sources which is
roughly equal to 27%. Furthermore we observe, that by removing from this sample
those bursts that may have any type of indirect redshift indicator and multiple
peaks gives the most probable contamination increases up to 34% (17 out of 49
sources). It is probable that a high degree of contamination by galactic
sources occurs among the single peak FREDs observed by Swift.Comment: Published to A&A, 4 pages, 5 figures, this arXiv version includes
appended table with all the bursts considered in this stud
Session-based concurrency in Maude:Executable semantics and type checking
Session types are a well-established approach to communication correctness in message-passing processes. Widely studied from a process calculi perspective, here we pursue an unexplored strand and investigate the use of the Maude system for implementing session-typed process languages and reasoning about session-typed process specifications. We present four technical contributions. First, we develop and implement in Maude an executable specification of the operational semantics of a session-typed π-calculus by Vasconcelos. Second, we also develop an executable specification of its associated algorithmic type checking, and describe how both specifications can be integrated. Third, we show that our executable specification can be coupled with reachability and model checking tools in Maude to detect well-typed but deadlocked processes. Finally, we demonstrate the robustness of our approach by adapting it to a higher-order session π-calculus, in which exchanged values include names but also abstractions (functions from names to processes). All in all, our contributions define a promising new approach to the (semi)automated analysis of communication correctness in message-passing concurrency
Metodología para la medición de la huella hídrica en la producción de tilapia, cachama y trucha: estudios de caso para el Valle del Cauca (Colombia)
(Eng) The pisciculture sector in Colombia, has grown 13% annually between 1988 and 2013, and it is the sixth major water user.
Considering the influence that pisciculture has over the water resources, the water footprint of pisciculture was studied
as a sustainability indicator, a method was developed to estimate the water footprint of the sector, which include not only
the direct and indirect components, but also the green, blue and grey water footprint. The method was applied to the three
most produced species in the country: tilapia (Oreochromis mossambicus), cachama (Piaractus brachypomus) and trout
(Oncorhynchus mykiss), to corresponding case studies in Valle del Cauca, Colombia. It was found that the water footprint
of tilapia culture is 5,486 m3/Ton, cachama culture is 6,193 m3/Ton, and trout culture is 19,854 m3/Ton. The highest total
water footprint for tilapia was that of the concentrated feed, followed by the blue water footprint, associated with the
amount of water that remains stored in the ponds, whereas for the cachama and trout, the highest water footprint was grey,
due to the high concentrations of solids and nutrients present in fish excretions and unconsumed feed.(Spa) El sector piscícola en Colombia creció en promedio 13% anual de 1988 a 2013 y es el sexto mayor usuario de agua en
el país. Considerando la presión que ejerce la producción piscícola sobre las fuentes de agua, se estudió la huella hídrica
(HH) de la piscicultura como un indicador de sostenibilidad. Para ello se desarrolló una metodología que mide la HH en el
sector, que incluye sus componentes directos e indirectos, así como las huellas hídricas verde, azul y gris. La metodología
se aplicó a las tres especies piscícolas más producidas en el país: tilapia (Oreochromis mossambicus), cachama (Piaractus
brachypomus) y trucha (Oncorhynchus mykiss), para sendos casos de estudio en el Valle del Cauca, Colombia. Se encontró
que la HH total del cultivo de tilapia es de 5,486 m3/Ton, la del cultivo de cachama de 6,193 m3/Ton y la del cultivo de
trucha de 19,854 m3/Ton. La huella hídrica total más alta para la tilapia fue la del alimento concentrado, seguida por la
huella hídrica azul, asociada a la cantidad de agua que permanece almacenada en los estanques; en la cachama y trucha
la mayor huella hídrica total fue la gris, relacionada con las altas concentraciones de sólidos y nutrientes, presentes en las
excretas de los peces y en el alimento concentrado no consumido
Variability of early autumn planktonic assemblages in the strait of Gibraltar: a regionalization analysis
The Strait of Gibraltar (SG) is the only connection of the Mediterranean Sea with the global circulation. The SG is an outstanding
marine region to explore physical-biological coupling of pelagic communities due to its hydrodynamic complexity, including strong
tidal forcing and marked spatial gradients and fronts. The authors have unravelled the role of the fortnightly tidal scale (spring and
neap tides) and local processes (upwelling and tidal-topographic mixing) that shape planktonic assemblages in the Strait. To do so,
an oceanographic cruise was taken in early autumn 2008 with a high-resolution grid sampling and spring/neap tidal conditions. The
planktonic features were captured using different automatic and semi-automatic techniques of plankton analyses (flow cytometry,
FlowCAM, LOPC and Ecotaxa) that allowed covering a wide range of sizes of the community from pico- to mesoplankton. The SG
was sectorized into two clusters based on the biogeochemical and main water column properties. Cluster 1 (CL1) covered shallow
productive areas around Cape Trafalgar (CT). CL1 presented higher concentrations of chlorophyll and nutrients, and phytoplankton
was mostly represented by Synechococcus and coastal diatoms while zooplankton had the highest percentage of meroplankton (31%).
In contrast, cluster 2 (CL2) covered open ocean waters and presented more oligotrophic features, i.e. nitrogen-depleted waters with
lower chlorophyll concentrations and a picoplankton community dominated by Prochlorococcus and holoplankton predominance in
mesozooplankton. Under early autumn conditions with overall nutrient-depleted and stratified waters, the CT area emerges as an ecosystem
where the constant tidal mixing and nutrients supply is coupled with an active production also being favored by high residence
times and finally shaping a plankton community with unique features in the area.En prensa0,56
Nanostructured supramolecular hydrogels: Towards the topical treatment of Psoriasis and other skin diseases
Supramolecular hydrogels were synthesized using a bis-imidazolium based amphiphile, and incorporating chemically diverse drugs, such as the cytostatics gemcitabine hydrochloride and methotrexate sodium salt, the immunosuppressive drug tacrolimus, as well as the corticoid drugs betamethasone 17-valerate and triamcinolone acetonide, and their potential as drug delivery agents in the dermal treatment of Psoriasis was evaluated. The rheological behavior of gels was studied, showing in all cases suitable viscoelastic properties for topical drug delivery. Scanning electron microscopy (SEM) shows that the drugs included have a great influence on the gel morphology at the microscopic level, as the incorporation of gemcitabine hydrochloride leads to slightly thicker fibers, the incorporation of tacrolimus induces flocculation and spherical precipitates, and the incorporation of methotrexate forms curled fibers. 1H NMR spectroscopy experiments show that these drugs not only remain dissolved at the interstitial space, but up to 72% of either gemcitabine or methotrexate, and up to 38% of tacrolimus, is retained within the gel fibers in gels formed with a 1:1 gelator:drug molar ratio. This unique fiber incorporation not only protects the drug from degradation, but also importantly induces a Two Phase Exponential drug release, where the first phase corresponds to the drug dissolved in the interstitial space, while the second phase corresponds to the drug exiting from the gel fibers, and where the speed in each phase is in accordance with the physicochemical properties of the drugs, opening perspectives for controlled delivery. Skin permeation ex vivo tests show how these gels successfully promote the drug permeation and retention inside the skin for reaching their therapeutic target, while in vivo experiments demonstrate that they decrease the hyperplasia and reduce the macroscopic tissue damage typically observed in psoriatic skin, significantly more than the drugs in solution. All these characteristics, beside the spontaneous and easy preparation (room temperature and soft stirring), make these gels a good alternative to other routes of administration for Psoriasis treatment, increasing the drug concentration at the target tissue, and minimizing side effects
Opioid pain medication prescription for chronic pain in primary care centers: the roles of pain acceptance, pain intensity, depressive symptoms, pain catastrophizing, sex, and age
Background: Psychological factors of patients may influence physicians’ decisions on prescribing opioid analgesics. However, few studies have sought to identify these factors. The present study had a double objective: (1) To identify the individual factors that differentiate patients who had been prescribed opioids for the management of chronic back pain from those who had not been prescribed opioids and (2) to determine which factors make significant and independent contributions to the prediction of opioid prescribing. Methods: A total of 675 patients from four primary care centers were included in the sample. Variables included sex, age, pain intensity, depressive symptoms, pain catastrophizing, and pain acceptance. Results: Although no differences were found between men and women, participants with chronic noncancer pain who were prescribed opioids were older, reported higher levels of pain intensity and depressive symptoms, and reported lower levels of pain-acceptance. An independent association was found between pain intensity and depressive symptoms and opioid prescribing. Conclusions: The findings suggest that patient factors influence physicians’ decisions on prescribing opioids. It may be useful for primary care physicians to be aware of the potential of these factors to bias their treatment decisions.info:eu-repo/semantics/publishedVersio
Finding influential nodes for integration in brain networks using optimal percolation theory
Global integration of information in the brain results from complex
interactions of segregated brain networks. Identifying the most influential
neuronal populations that efficiently bind these networks is a fundamental
problem of systems neuroscience. Here we apply optimal percolation theory and
pharmacogenetic interventions in-vivo to predict and subsequently target nodes
that are essential for global integration of a memory network in rodents. The
theory predicts that integration in the memory network is mediated by a set of
low-degree nodes located in the nucleus accumbens. This result is confirmed
with pharmacogenetic inactivation of the nucleus accumbens, which eliminates
the formation of the memory network, while inactivations of other brain areas
leave the network intact. Thus, optimal percolation theory predicts essential
nodes in brain networks. This could be used to identify targets of
interventions to modulate brain function.Comment: 20 pages, 6 figures, Supplementary Inf
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