4,806 research outputs found
DISTRIBUTION OF HEAVY METALS CONCENTRATIONS IN SOILS AROUND THE INTERNATIONAL ATHENS AIRPORT (GREECE). AN ASSESSMENT ON PRELIMINARY DATA
Τα εδάφη, ως αποδέκτες της ατμοσφαιρικής απόθεσης μετάλλων, αποτελούν αξιόπιστους δείκτες ρύπανσης, ιδιαίτερα στις περιπτώσεις που εντοπίζονται πιθανές σημειακές πηγές ρύπανσης σε χερσαία οικοσυστήματα. Σκοπός της παρούσας μελέτης ήταν η εκτίμηση της κατανομής των συγκεντρώσεων του Cu, Zn, Fe, Mn, Ni, Cr και Ba σε εδάφη κοντά στο Διεθνές Αεροδρόμιο Αθηνών «Ελ. Βενιζέλος», στην Αττική. Σε 86 επιφανειακά δείγματα προσδιορίστηκαν οι ολικές συγκεντρώσεις μετάλλων, στο εκχύλισμα που προέκυψε μετά από κατεργασία με «aqua regia». Οι διάμεσες τιμές των συγκεντρώσεων του Cu, Zn, Fe, Mn, Ni, Cr και Ba ήταν 23, 81, 22x103 , 497, 87, 74, 75 και 423 mg kg-1 αντίστοιχα. Αν και οι διάμεσες τιμές δε θεωρούνται τόσο υψηλές, οι τιμές του ενενηκοστού εκατοστημόριου για ορισμένα μέταλλα θεωρούνται υψηλές, υποδεικνύοντας πιθανό εμπλουτισμό του εδάφους με τα μέταλλα αυτά. Επίσης, παρατηρήθηκε μια τάση για αυξημένες συγκεντρώσεις του Zn και Cr κατά μήκος του άξονα Βορράς-Νότος καθώς και του Pb, Cu και Ni στο βόρειο τμήμα της περιοχής που μελετήθηκε. Τα προκαταρκτικά αποτελέσματα που προέκυψαν, υποβλήθηκαν σε ανάλυση κατά συστάδες και σε αξιολόγηση των συντελεστών εμπλουτισμού των μετάλλων, ως μια πρώτη προσέγγιση του διαχωρισμού μεταξύ φυσικής και ανθρωπογενούς συνεισφοράς των μετάλλων στα εδάφη της περιοχής. Τόσο οι συντελεστές εμπλουτισμού όσο και η ανάλυση κατά συστάδες, υποδηλώνουν δευτερογενή συγκέντρωση των Pb, Cu και Zn στα εδάφη της υπό μελέτη περιοχής.Soils are receptors of atmospheric metal depositions and hence reliable indicators of pollution phenomena, especially for cases that potential site specific pollution sources are detected in terrestrial ecosystems. The purpose of this study was to assess the distribution of Cu, Zn, Fe, Mn, Ni, Cr, Pb, and Ba concentrations in soils nearby the International Athens Airport “El. Venizelos”, in Attica, Greece. Total metal concentrations were determined in 86 topsoil aqua regia extracts and the median values for Cu, Zn, Fe, Mn, Ni, Cr, Pb, and Ba concentrations were 23, 81, 22x103 , 497, 87, 74, 75, and 423 mg kg-1 respectively. Though median values are not considered as high, the 90th percentile concentration values for some metals are high, indicating possible soil enrichment by these metals. A tendency for increased concentrations of Zn and Cr along the north-south axis and of Pb, Cu and Ni at the northern part of the studied area was also observed. As a first approach to discriminate between natural and anthropogenic metal contributions in the soils of the area, the obtained preliminary data were subjected to cluster analysis and to the evaluation of metals Enrichment Factors (EFs). Both EF values and cluster analysis results suggested secondary Pb, Cu and Zn site specific accumulation in the soils of the studied area
Multicolour detection of every chromosome as a means of detecting mosaicism and nuclear organisation in human embryonic nuclei
Fluorescence in situ Hybridisation (FISH) revolutionised cytogenetics using fluorescently labelled probes with high affinity with target (nuclear) DNA. By the early 1990s FISH was adopted as a means of PGD sexing for couples at risk of transmitting X-linked disorders and later for detection of unbalanced translocations. Following a rise in popularity of PGD by FISH for sexing and the availability of multicolour probes (5-8 colour), the use of FISH was expanded to the detection of aneuploidy and selective implantation of embryos more likely to be euploid, the rationale being to increase pregnancy rates (referral categories were typically advanced maternal age, repeated IVF failure, repeated miscarriage or severe male factor infertility). Despite initial reports of an increase in implantation rates, reduction in trisomic offspring and spontaneous abortions criticism centred around experimental design (including lack of randomisation), inadequate control groups and lack of report on live births. Eleven randomised control trials (RCTs) (2004-2010) showed that PGS with FISH did not increase delivery rates with some demonstrating adverse outcomes. These RCTs, parallel improvements in culturing and cryopreservation and a shift to blastocyst biopsy essentially outdated FISH as a tool for PGS and it has now been replaced by newer technologies (array CGH, SNP arrays, qRT-PCR and NGS). Cell-by-cell follow up analysis of individual blastomeres in non-transferred embryos is however usually prohibitively expensive by these new approaches and thus FISH remains an invaluable resource for the study of mosaicosm and nuclear organization. We thus developed the approach described herein for the FISH detection of chromosome copy number of all 24 human chromosomes. This approach involves 4 sequential layers of hybridization, each with 6 spectrally distinct fluorochromes and a bespoke capturing system. Here we report previously published studies and hitherto unreported data indicating that 24 chromosome FISH is a useful tool for studying chromosome mosaicism, one of the most hotly debated topics currently in preimplantation genetics. Our results suggest that mosaic embryo aneuploidy is not highly significantly correlated to maternal age, probably due, in part, to the large preponderance of post-zygotic (mitotic) errors. Chromosome loss (anaphase lag) appears to be the most common mechanism, followed by chromosome gain (endoreduplication), however 3:1 mitotic non- disjunction of chromosomes appears to be rare. Nuclear organisation (i.e. the spatial and temporal topology of chromosomes or sub-chromosomal compartments) studies indicate that human morula or blastocyst embryos (day 4-5) appear to adopt a "chromocentric" pattern (i.e. almost all centromeric signals reside in the innermost regions of the nuclear volume). By the blastocyst stage however, a more ordered organisation with spatial and temporal cues important for embryo development appears. We have however found no association between aneuploidy and nuclear organization using this approach despite our earlier studies. In conclusion, while FISH is mostly "dead and buried" for mainstream PGS, it still has a place for basic biology studies; the development of a 24 chromosome protocol extends the power of this analysis
RNA Targeting and Gene Editing Strategies for Transthyretin Amyloidosis
Transthyretin (TTR) is a tetrameric protein synthesized primarily by the liver. TTR can misfold into pathogenic ATTR amyloid fibrils that deposit in the nerves and heart, causing a progressive and debilitating polyneuropathy (PN) and life-threatening cardiomyopathy (CM). Therapeutic strategies, which are aimed at reducing ongoing ATTR amyloid fibrillogenesis, include stabilization of the circulating TTR tetramer or reduction of TTR synthesis. Small interfering RNA (siRNA) or antisense oligonucleotide (ASO) drugs are highly effective at disrupting the complementary mRNA and inhibiting TTR synthesis. Since their development, patisiran (siRNA), vutrisiran (siRNA) and inotersen (ASO) have all been licensed for treatment of ATTR-PN, and early data suggest these drugs may have efficacy in treating ATTR-CM. An ongoing phase 3 clinical trial will evaluate the efficacy of eplontersen (ASO) in the treatment of both ATTR-PN and ATTR-CM, and a recent phase 1 trial demonstrated the safety of novel in vivo CRISPR-Cas9 gene-editing therapy in patients with ATTR amyloidosis. Recent results from trials of gene silencer and gene-editing therapies suggest these novel therapeutic agents have the potential to substantially alter the landscape of treatment for ATTR amyloidosis. Their success has already changed the perception of ATTR amyloidosis from a universally progressive and fatal disease to one that is treatable through availability of highly specific and effective disease-modifying therapies. However, important questions remain including long-term safety of these drugs, potential for off-target gene editing, and how best to monitor the cardiac response to treatment.Kindly check and confirm the processed running title.This is correct
Uncertainty and Quality rating in Analytical Vulnerability Assessment
Fragility curves represent a major component of seismic risk and vulnerability assessment of buildings
and infrastructure facilities. A recently conducted extensive literature review under the framework of
developing the “GEM Guide for Selecting of Existing Analytical Fragility Curves and Compilation of
the Database”, shows that there is a wealth of existing analytically derived fragility curves that can be
used for future applications. However, the main challenge in using these curves is how to identify and,
if necessary, combine suitable fragility curves from a pool of curves with different characteristics and,
often unknown, reliability. The present article introduces a rating system that has been developed
following detail review and critique of the various methodologies on the derivation of analytical
fragility curves that have been generated in the past two decades. The main scope is to provide
guidance, either in choosing suitable and robust existing fragility curves or in generating new fragility
curves. The quality rating system rates the quality of a curve according to the effect that various
parameters, simulation procedures and assumptions on the reliability of fragility curve. It also assists
and steers potential analysts towards a better identification and quantification of expected uncertainties
throughout the process
Deep roots: Improving CNN efficiency with hierarchical filter groups
We propose a new method for creating computationally efficient and compact
convolutional neural networks (CNNs) using a novel sparse connection structure
that resembles a tree root. This allows a significant reduction in
computational cost and number of parameters compared to state-of-the-art deep
CNNs, without compromising accuracy, by exploiting the sparsity of inter-layer
filter dependencies. We validate our approach by using it to train more
efficient variants of state-of-the-art CNN architectures, evaluated on the
CIFAR10 and ILSVRC datasets. Our results show similar or higher accuracy than
the baseline architectures with much less computation, as measured by CPU and
GPU timings. For example, for ResNet 50, our model has 40% fewer parameters,
45% fewer floating point operations, and is 31% (12%) faster on a CPU (GPU).
For the deeper ResNet 200 our model has 25% fewer floating point operations and
44% fewer parameters, while maintaining state-of-the-art accuracy. For
GoogLeNet, our model has 7% fewer parameters and is 21% (16%) faster on a CPU
(GPU).Microsoft Research PhD Scholarshi
IgG anti-apolipoprotein A-1 antibodies in patients with systemic lupus erythematosus are associated with disease activity and corticosteroid therapy: an observational study.
IgG anti-apolipoprotein A-1 (IgG anti-apoA-1) antibodies are present in patients with systemic lupus erythematosus (SLE) and may link inflammatory disease activity and the increased risk of developing atherosclerosis and cardiovascular disease (CVD) in these patients. We carried out a rigorous analysis of the associations between IgG anti-apoA-1 levels and disease activity, drug therapy, serology, damage, mortality and CVD events in a large British SLE cohort
Evidence for multiple impurity bands in sodium-doped silicon MOSFETs
We report measurements of the temperature-dependent conductivity in a silicon
metal-oxide-semiconductor field-effect transistor that contains sodium
impurities in the oxide layer. We explain the variation of conductivity in
terms of Coulomb interactions that are partially screened by the proximity of
the metal gate. The study of the conductivity exponential prefactor and the
localization length as a function of gate voltage have allowed us to determine
the electronic density of states and has provided arguments for the presence of
two distinct bands and a soft gap at low temperature.Comment: 4 pages; 5 figures; Published in PRB Rapid-Communication
A Spatially Resolved `Inside-out' Outburst of IP Pegasi
We present a comprehensive photometric dataset taken over the entire outburst
of the eclipsing dwarf nova IP Peg in September/October 1997. Analysis of the
lightcurves taken over the long rise to the peak-of-outburst shows conclusively
that the outburst started near the centre of the disc and moved outwards. This
is the first dataset that spatially resolves such an outburst. The dataset is
consistent with the idea that long rise times are indicative of such
`inside-out' outbursts. We show how the thickness and the radius of the disc,
along with the mass transfer rate change over the whole outburst. In addition,
we show evidence of the secondary and the irradiation thereof. We discuss the
possibility of spiral shocks in the disc; however we find no conclusive
evidence of their existence in this dataset.Comment: 8 pages, 8 figures, to be appear in MNRA
Quantum Separability and Entanglement Detection via Entanglement-Witness Search and Global Optimization
We focus on determining the separability of an unknown bipartite quantum
state by invoking a sufficiently large subset of all possible
entanglement witnesses given the expected value of each element of a set of
mutually orthogonal observables. We review the concept of an entanglement
witness from the geometrical point of view and use this geometry to show that
the set of separable states is not a polytope and to characterize the class of
entanglement witnesses (observables) that detect entangled states on opposite
sides of the set of separable states. All this serves to motivate a classical
algorithm which, given the expected values of a subset of an orthogonal basis
of observables of an otherwise unknown quantum state, searches for an
entanglement witness in the span of the subset of observables. The idea of such
an algorithm, which is an efficient reduction of the quantum separability
problem to a global optimization problem, was introduced in PRA 70 060303(R),
where it was shown to be an improvement on the naive approach for the quantum
separability problem (exhaustive search for a decomposition of the given state
into a convex combination of separable states). The last section of the paper
discusses in more generality such algorithms, which, in our case, assume a
subroutine that computes the global maximum of a real function of several
variables. Despite this, we anticipate that such algorithms will perform
sufficiently well on small instances that they will render a feasible test for
separability in some cases of interest (e.g. in 3-by-3 dimensional systems)
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