1,454 research outputs found
THE PHASE-ANGLE METHOD FOR ELECTRICAL-RESISTIVITY APPLIED TO THE HOLLOW CIRCULAR-CYLINDER GEOMETRY
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Master of Computational Biology & Bioinformatics
XIX ENBE Annual Meeting of the Portuguese Association for Evolutionary Biology, 18-19 December 2023, Lisboninfo:eu-repo/semantics/publishedVersio
A Nanostructured Piezoelectric Immunosensor for Detection of Human Cardiac Troponin T
Conselho Nacional de Desenvolvimento CientĂfico e TecnolĂłgico (CNPq)A piezoelectric immunosensor based on gold nanoparticles (AuNPs) co-immobilized on a dithiol-modified surface is proposed for detection of human cardiac troponin T (TnT). Anti-human troponin T (anti-TnT) antibodies were covalently immobilized on the nanostructured electrode surface by thiol-aldehyde linkages. In a homogeneous bulk solution, TnT was captured by anti-TnT immobilized on the QCM electrode. Cyclic voltammetry studies were used to characterize the AuNPs layer on the electrode surface and the anti-TnT immobilization steps. The QCM-flow immunosensor exhibited good reliability, measuring concentrations of TnT from 0.003 to 0.5 ng mL(-1) in human serum with high linearity (r = 0.989; p < 0.01). The immunosensor exhibited a 7% coefficient of variation and 0.0015 ng mL(-1) limit of detection, indicating a high reproducibility and sensitivity. The proposed QCM nanostructured immunosensor is easy to use and has promising potential in the diagnosis of acute myocardial infarction due to its speed and high sensitivity.11111078510797Conselho Nacional de Desenvolvimento CientĂfico e TecnolĂłgico (CNPq)Conselho Nacional de Desenvolvimento CientĂfico e TecnolĂłgico (CNPq)CNPq [483242/2010-1
A Substantial Amount of Hidden Magnetic Energy in the Quiet Sun
Deciphering and understanding the small-scale magnetic activity of the quiet
solar photosphere should help to solve many of the key problems of solar and
stellar physics, such as the magnetic coupling to the outer atmosphere and the
coronal heating. At present, we can see only of the complex
magnetism of the quiet Sun, which highlights the need to develop a reliable way
to investigate the remaining 99%. Here we report three-dimensional radiative
tranfer modelling of scattering polarization in atomic and molecular lines that
indicates the presence of hidden, mixed-polarity fields on subresolution
scales. Combining this modelling with recent observational data we find a
ubiquitous tangled magnetic field with an average strength of G,
which is much stronger in the intergranular regions of solar surface convection
than in the granular regions. So the average magnetic energy density in the
quiet solar photosphere is at least two orders of magnitude greater than that
derived from simplistic one-dimensional investigations, and sufficient to
balance radiative energy losses from the solar chromosphere.Comment: 21 pages and 2 figures (letter published in Nature on July 15, 2004
Universal features of correlated bursty behaviour
Inhomogeneous temporal processes, like those appearing in human
communications, neuron spike trains, and seismic signals, consist of
high-activity bursty intervals alternating with long low-activity periods. In
recent studies such bursty behavior has been characterized by a fat-tailed
inter-event time distribution, while temporal correlations were measured by the
autocorrelation function. However, these characteristic functions are not
capable to fully characterize temporally correlated heterogenous behavior. Here
we show that the distribution of the number of events in a bursty period serves
as a good indicator of the dependencies, leading to the universal observation
of power-law distribution in a broad class of phenomena. We find that the
correlations in these quite different systems can be commonly interpreted by
memory effects and described by a simple phenomenological model, which displays
temporal behavior qualitatively similar to that in real systems
The association between family and community social capital and health risk behaviours in young people: an integrative review
Background:
Health risk behaviours known to result in poorer outcomes in adulthood are generally established in late childhood and adolescence. These âriskyâ behaviours include smoking, alcohol and illicit drug use and sexual risk taking. While the role of social capital in the establishment of health risk behaviours in young people has been explored, to date, no attempt has been made to consolidate the evidence in the form of a review. Thus, this integrative review was undertaken to identify and synthesise research findings on the role and impact of family and community social capital on health risk behaviours in young people and provide a consolidated evidence base to inform multi-sectorial policy and practice.<p></p>
Methods:
Key electronic databases were searched (i.e. ASSIA, CINAHL, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Database of Abstracts of Reviews of Effects, Embase, Medline, PsycINFO, Sociological Abstracts) for relevant studies and this was complemented by hand searching. Inclusion/exclusion criteria were applied and data was extracted from the included studies. Heterogeneity in study design and the outcomes assessed precluded meta-analysis/meta-synthesis; the results are therefore presented in narrative form.<p></p>
Results:
Thirty-four papers satisfied the review inclusion criteria; most were cross-sectional surveys. The majority of the studies were conducted in North America (n=25), with three being conducted in the UK. Sample sizes ranged from 61 to 98,340. The synthesised evidence demonstrates that social capital is an important construct for understanding the establishment of health risk behaviours in young people. The different elements of family and community social capital varied in terms of their saliency within each behavioural domain, with positive parentâchild relations, parental monitoring, religiosity and school quality being particularly important in reducing risk.<p></p>
Conclusions:
This review is the first to systematically synthesise research findings about the association between social capital and health risk behaviours in young people. While providing evidence that may inform the development of interventions framed around social capital, the review also highlights key areas where further research is required to provide a fuller account of the nature and role of social capital in influencing the uptake of health risk behaviours.<p></p>
The carnivorous feeding behavior of early Homo at HWK EE, Bed II, Olduvai Gorge, Tanzania
The regular consumption of large mammal carcasses, as evidenced by butchery marks on fossils recovered from Early Stone Age archaeological sites, roughly coincides with the appearance of Homo habilis. However, the significance of this niche expansion cannot be appreciated without an understanding of hominin feeding behavior and their ecological interactions with mammalian carnivores. The Olduvai Geochronology and Archaeology Project (OGAP) has recovered a large and well-preserved fossil assemblage from the HWK EE site, which was deposited just prior to the first appearance of Acheulean technology at Olduvai Gorge and likely represents one of the last H. habilis sites at Olduvai. This taphonomic analysis of the larger mammal fossil assemblage excavated from HWK EE shows evidence of multiple occupations over a long period of time, suggesting the site offered resources that were attractive to hominins. There was a water source indicated by the presence of fish, crocodiles, and hippos, and there was possible tree cover in an otherwise open habitat. The site preserves several stratigraphic intervals with large fossil and artifact assemblages within two of these intervals. Feeding traces on bone surfaces suggest hominins at the site obtained substantial amounts of flesh and marrow, particularly from smaller size group 1-2 carcasses, and exploited a wide range of taxa, including megafauna. A strong carnivore signal suggests hominins scavenged much of their animal foods during the two main stratigraphic intervals. In the later interval, lower carnivore tooth mark and hammerstone percussion mark frequencies, in addition to high epiphyseal to shaft fragment ratios, suggest hominins and carnivores did not fully exploit bone marrow and grease, which may have been acquired from nutritionally-stressed animals that died during a dry period at Olduvai. The diversity of fauna that preserve evidence of butchery suggests that the HWK EE hominins were opportunistic in their acquisition of carcass foods
Theoretical study of the insulating oxides and nitrides: SiO2, GeO2, Al2O3, Si3N4, and Ge3N4
An extensive theoretical study is performed for wide bandgap crystalline
oxides and nitrides, namely, SiO_{2}, GeO_{2}, Al_{2}O_{3}, Si_{3}N_{4}, and
Ge_{3}N_{4}. Their important polymorphs are considered which are for SiO_{2}:
-quartz, - and -cristobalite and stishovite, for
GeO_{2}: -quartz, and rutile, for Al_{2}O_{3}: -phase, for
Si_{3}N_{4} and Ge_{3}N_{4}: - and -phases. This work
constitutes a comprehensive account of both electronic structure and the
elastic properties of these important insulating oxides and nitrides obtained
with high accuracy based on density functional theory within the local density
approximation. Two different norm-conserving \textit{ab initio}
pseudopotentials have been tested which agree in all respects with the only
exception arising for the elastic properties of rutile GeO_{2}. The agreement
with experimental values, when available, are seen to be highly satisfactory.
The uniformity and the well convergence of this approach enables an unbiased
assessment of important physical parameters within each material and among
different insulating oxide and nitrides. The computed static electric
susceptibilities are observed to display a strong correlation with their mass
densities. There is a marked discrepancy between the considered oxides and
nitrides with the latter having sudden increase of density of states away from
the respective band edges. This is expected to give rise to excessive carrier
scattering which can practically preclude bulk impact ionization process in
Si_{3}N_{4} and Ge_{3}N_{4}.Comment: Published version, 10 pages, 8 figure
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