1,263 research outputs found
Naturally-occurring stable isotopes as direct measures of larval feeding efficiency, nutrient incorporation and turnover
environmental conditions on stable isotope incorporation will be of broad relevance not only in terms of larval nutrition but can also more broadly inform the design and interpretation of ecological studies
Time-dependent effects in melting and phase change for laser-shocked iron
Using the Linac Coherent Light Source facility at the Stanford Linac Coherent Light Source National Accelerator Laboratory, we have observed X-ray scattering from iron compressed with laser-driven shocks to earth-core-like pressures above 400 GPa. The data show cases where melting is incomplete and we observe hexagonal-close-packed crystal structure at shock compressed densities up to 14.0 g cm-3 but no evidence of a double-hexagonal-close-packed crystal. The observation of a crystalline structure at these densities, where shock heating is expected to be in excess of the equilibrium melt temperature, may indicate superheating of the solid. These results are important for equation of state modeling at high strain rates relevant for impact scenarios and laser-driven shock-wave experiments
Recent advances in the application of stable isotopes as nutritional tools in aquaculture
From an ecological point of view, aquaculture systems consist of simple food webs having a limited number of nutritional sources. These characteristics facilitate the application of stable isotope ratios of carbon and nitrogen (δ13C and δ15N) to assess the flow of dietary components. Due to rapid and measurable bioaccumulation of the heavier stable isotopes, such isotopic shifts can be tracked at different times and at each trophic step to provide an indicator of what dietary components are being incorporated into animal tissue and how fast. The present manuscript presents results from recent, controlled nutritional experiments designed to quantify the relative contribution of dietary carbon and nitrogen supplied by different dietary items. Stable isotopes ratios were measured in a range of food sources and experimental animals. In a first experiment, juvenile shrimp Litopenaeus vannamei were reared on co-feeding regimes having different proportions of live biomass of the green macroalgae Ulva clathrata and inert feed in order to identify nutritional contributions to tissue growth using dual stable isotope analysis. In another trial, nitrogen stable isotopes were measured to explore the relative dietary nitrogen contributions from fish meal and pea meal (Pisum sativum) to the growth of white shrimp postlarvae fed low protein diets having different proportions of both ingredients. In a third, multidisciplinary experiment, Senegalese sole (Solea senegalensis) larvae were used as a model to evaluate the effect of different larval feeding regimes on (1) trypsinogen gene expression (ssetryp1), (2) trypsin and chymotrypsin activities and (3) changes in stable isotope composition to estimate the assimilation of dietary carbon from the larval diets
The State of the (CHI)Art
We are all researchers, practitioners, and educators - but many of us are also artists, makers, curators. Our arts practice is part of what makes up our sense of self, but also influences our interests and directions in digital and technological enquiry. There exist spaces where the traditional lives alongside the computational, or where the two are blended, no less valid in purpose or value. We seek to investigate this liminal environment, and explore the current state of art in HCI, computer science and other related fields, shifting boundaries as to what "art"is in these spaces. By bringing together like-minded and creative individuals, this workshop aims to both inspire and legitimise our diverse practices, present viewpoints, create meaningful outputs, host discussions, and work toward the future of this plurality
Quantum Fields and Extended Objects in Space-Times with Constant Curvature Spatial Section
The heat-kernel expansion and -regularization techniques for quantum
field theory and extended objects on curved space-times are reviewed. In
particular, ultrastatic space-times with spatial section consisting in manifold
with constant curvature are discussed in detail. Several mathematical results,
relevant to physical applications are presented, including exact solutions of
the heat-kernel equation, a simple exposition of hyperbolic geometry and an
elementary derivation of the Selberg trace formula. With regards to the
physical applications, the vacuum energy for scalar fields, the one-loop
renormalization of a self-interacting scalar field theory on a hyperbolic
space-time, with a discussion on the topological symmetry breaking, the finite
temperature effects and the Bose-Einstein condensation, are considered. Some
attempts to generalize the results to extended objects are also presented,
including some remarks on path integral quantization, asymptotic properties of
extended objects and a novel representation for the one-loop (super)string free
energy.Comment: Latex file, 122 page
How protective is cervical cancer screening against cervical cancer mortality in developing countries? The Colombian case
<p>Abstract</p> <p>Background</p> <p>Cervical cancer is one of the top causes of cancer morbidity and mortality in Colombia despite the existence of a national preventive program. Screening coverage with cervical cytology does not explain the lack of success of the program in reducing incidence and mortality rates by cervical cancer. To address this problem an ecological analysis, at department level, was carried out in Colombia to assess the relationship between cervical screening characteristics and cervical cancer mortality rates.</p> <p>Methods</p> <p>Mortality rates by cervical cancer were estimated at the department level for the period 2000-2005. Levels of mortality rates were compared to cervical screening coverage and other characteristics of the program. A Poisson regression was used to estimate the effect of different dimensions of program performance on mortality by cervical cancer.</p> <p>Results</p> <p>Screening coverage ranged from 28.7% to 65.6% by department but increases on this variable were not related to decreases in mortality rates. A significant reduction in mortality was found in departments where a higher proportion of women looked for medical advice when abnormal findings were reported in Pap smears. Geographic areas where a higher proportion of women lack health insurance had higher rates of mortality by cervical cancer.</p> <p>Conclusions</p> <p>These results suggest that coverage is not adequate to prevent mortality due to cervical cancer if women with abnormal results are not provided with adequate follow up and treatment. The role of different dimensions of health care such as insurance coverage, quality of care, and barriers for accessing health care needs to be evaluated and addressed in future studies.</p
Measurement of the cross-section and charge asymmetry of bosons produced in proton-proton collisions at TeV with the ATLAS detector
This paper presents measurements of the and cross-sections and the associated charge asymmetry as a
function of the absolute pseudorapidity of the decay muon. The data were
collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with
the ATLAS experiment at the LHC and correspond to a total integrated luminosity
of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements
varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the
1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured
with an uncertainty between 0.002 and 0.003. The results are compared with
predictions based on next-to-next-to-leading-order calculations with various
parton distribution functions and have the sensitivity to discriminate between
them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables,
submitted to EPJC. All figures including auxiliary figures are available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13
Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector
A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13 TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV
Bolivia and the paradoxes of democratic consolidation
In Bolivia from the 1990s on, two presidents were ousted by popular protests, and protests were rampant. The protests expressed a growing discontent not only with successive administrations and their policies but with politics itself. The polity failed to built trust in democracy, ignored or repressed protests, and thus contributed to a process of democratic "deconsolidation." The main factors were corruption and the reluctance of the traditional political parties to discuss the neoliberal economic model. As a result, the current administration of Evo Morales faces two challenges: to change economic policies and to repair the support for democracy
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