1,230 research outputs found
Empirical multi-wavelength prediction method for very high energy gamma-ray emitting BL Lacs
Aim: We have collected the most complete multi-wavelength () dataset of very high energy (VHE) -ray emitting (TeV) BL
Lacs, which are the most numerous extragalactic VHE sources. Using significant
correlations between different bands, we aim to identify the best TeV BL Lac
candidates that can be discovered by the current and next generation of imaging
air Cherenkov telescopes.
Methods: We formed five datasets from lower energy data, i.e. radio,
mid-infrared, optical, X-rays, and GeV -ray, and five VHE -ray
datasets to perform a correlation study between different bands and to
construct the prediction method. The low energy datasets were averaged for
individual sources, while the VHE -ray data were divided into subsets
according to the flux state of the source. We then looked for significant
correlations and determined their best-fit parameters. Using the best-fit
parameters we predicted the level of VHE -ray flux for a sample of 182
BL Lacs, which have not been detected at TeV energies. We identified the most
promising TeV BL Lac candidates based on the predicted VHE -ray flux
for each source.
Results: We found 14 significant correlations between radio, mid-infrared,
optical, -ray, and VHE -ray bands. The correlation between
optical and VHE -ray luminosity is established for the first time. We
attribute this to the more complete sample and more accurate handling of host
galaxy flux in our work. We found nine BL Lac candidates whose predicted VHE
-ray flux is high enough for detection in less than 25 hours with
current imaging air Cherenkov telescopes.Comment: 10 pages, 2 figures, 4 Table
Numerical simulation of the dynamic response in pulse-loaded fibre-metal-laminated plates
This article presents a three-dimensional constitutive model to replicate the dynamic response of blastloaded fibre–metal laminates made of 2024-0 aluminium alloy and woven composite (glass fibre–reinforced polypropylene). Simulation of the dynamic response is challenging when extreme localised loads are of concern and requires reliable material constitutive models as well as accurate modelling techniques. It is well known that back layers in a fibre–metal laminate provide structural support for front layers; thus, proper modelling of constituent failure and degradation is essential to understanding structural damage and failure. The improved developed model to analyse damage initiation, progression and failure of the composite is implemented in finite element code ABAQUS, and a good correlation is observed with experimental results for displacements of the back and front faces as presented by other researchers. The model was also able to predict accurately the tearing impulses. Finally, the concepts of the ‘efficiency of the charge’ and ‘effectiveness of the target’ are proposed in the context of localised blast loading on a structure. Dimensionless parameters are introduced to quantify these parameters
Constructive approximation in de Branges-Rovnyak spaces
In most classical holomorphic function spaces on the unit disk, a function
can be approximated in the norm of the space by its dilates
f\_r(z):=f(rz)~(r \textless{} 1). We show that this is \emph{not} the case
for the de Branges--Rovnyak spaces \cH(b). More precisely, we give an example
of a non-extreme point of the unit ball of and a function
f\in\cH(b) such that \lim\_{r\to1^-}\|f\_r\|\_{\cH(b)}=\infty. It is known
that, if is a non-extreme point of the unit ball of , then
polynomials are dense in \cH(b). We give the first constructive proof of this
fact
Introducing a simple and economical method to purify Giardia lamblia cysts
Direct microscopic examination of stool to diagnosis giardiasis (wet mount) has low diagnostic value, but immunologic methods (like IFA and especially ELISA) that are based on the determination of parasite antigens in fecal samples (antigen detection) have relatively high sensitivity and specialty. To prepare anti-Giardia lamblia antibodies needed to design diagnostic kits as well as parasite culture and other molecular studies, we require purification of the parasite cysts. In this study, we designed a rapid, simple and inexpensive method to purify parasite cysts from fecal samples of the patients suffering from giardiasis. Initially, fecal samples that the presence of G. lamblia in them was affirmed by direct microscopic observation of cysts were subjected to various purification methods like one- and twophase sucrose gradient isolation, percoll-sucrose gradient isolation, and a modified two-phase method run by 0.85 and 1.5 M sucrose. The first procedure contained some contents of bacteria and small particles of feces. In the second and third procedure, bacteria were almost removed and the cysts were intact but the suspension contained some extras and cellulose particles. The recovery rate for modified two-phase method was 1.5 × 104 cysts for each two grams of fecal sample. In this study, by using and comparing with the results of some other studies, we introduce and run a modified method that in fact is a mélange of them with some changes. So this method could be recommended as a fast, advantageous and simple method in purification of G. lamblia cysts.Key words: Giardia lamblia, cyst, purification
SAG2 locus genotyping of Toxoplasma gondii in meat products of East Azerbaijan Province, North West of Iran During 2010-2011
Toxoplasmosis is an infection caused by Toxoplasma gondii, an intracellular obligate parasite. Its transmission is usually attributed to ingestion of undercooked or raw meat. The aim of this study was the detection and genotyping of T. gondii in meat products using the molecular method in East Azerbaijan. DNA was extracted from 164 meat products sample obtained from 15 commercial establishments. Nested polymerase chain reaction with specific primers for Toxoplasma gondii SAG2 locus was used for detection of the parasite in samples. Genotyping was carried out by digestion of PCR products with restriction enzymes Cfo1 and Sau3AI. T. gondii DNA was detected in 16.6, 19.1, 15 and 56.6%, in salami, sausages, and hamburger and kebab samples, respectively. Genotyping by restriction fragment length polymorphism (RFLP) analysis of SAG2 locus revealed that all of the samples belonged to genotype I. The detection of the parasite in uncooked meat and commercial meat products, and the high ratio of seropositive slaughtered animals, emphasis that the risk still exists for food -born toxoplasmosis.Key words: Toxoplasma gondii, SAG2, genotyping, meat products
Seismic landslide hazard mapping for Greater Vancouver, British Columbia
The lower Mainland of southwest British Columbia (BC) hosts about 3.5 million people and significant infrastructures of national importance. Southwestern BC has the highest seismic risk in Canada with significant potential to cause earthquake-induced hazards including tsunamis, liquefaction and landslides. A Cascadia mega-thrust (MW 9) earthquake is predicted to generate $75 billion Canadian dollars in losses. This damage can be resulted from ground shaking or its secondary phenomena like landslides; ground shaking during earthquakes may trigger landslides that can damage or destroy buildings, bury roads and highways and kill and injure people. In Canada, during the past century and a half, landslides have caused more fatality than all other natural hazards combined.
Seismic hazard mapping for landslides integrates topographic, geotechnical and seismological information to develop the earthquake-induced slope displacements map which is indicator of seismic landslide potential. In this study we use a pseudo-probabilistic Newmark displacement analyses for regional landslide susceptibility mapping and its application will be illustrated with developing earthquake induced landslide hazard map for the quadrangle in Greater Vancouver area. The predicted displacements are assigned to the defined grids to come up with the final seismic landslide hazard map. The seismic landslide hazard map predicts very low hazard level (displacementcm) for the selected region which is in agreement with the observations in our field survey in July 2018 where no signs of deformation were recorded (e.g. cracks, settlements, previous landslides, scarps)
Genome-wide analysis of alternative splicing events in Hordeum vulgare: highlighting retention of intron-based splicing and its possible function through network analysis
In this study, using homology mapping of assembled expressed sequence tags against the genomic data, we identified alternative splicing events in barley. Results demonstrated that intron retention is frequently associated with specific abiotic stresses. Network analysis resulted in discovery of some specific sub-networks between miRNAs and transcription factors in genes with high number of alternative splicing, such as cross talk between SPL2, SPL10 and SPL11 regulated by miR156 and miR157 families. To confirm the alternative splicing events, elongation factor protein (MLOC_3412) was selected followed by experimental verification of the predicted splice variants by Semi quantitative Reverse Transcription PCR (qRT-PCR). Our novel integrative approach opens a new avenue for functional annotation of alternative splicing through regulatory-based network discovery.Bahman Panahi, Seyed Abolghasem Mohammadi, Reyhaneh Ebrahimi Khaksefidi, Jalil Fallah Mehrabadi, Esmaeil Ebrahimi
Designing of enzyme linked immunosorbent assay (ELISA) kit for diagnosis copro-antigens of Giardia lamblia
The sensitivity of microscopic examination of fecal samples to recognize Giardia parasites is low. In the methods based on antigen scanning of parasites such as enzyme linked immunosorbent assay (ELISA), copro-antigens of parasite will be traced and diagnosed even if the live parasite is absent in the fecal samples. To design this method, a pure antibody against parasite as well as an antibody conjugated to a proper enzyme is needed. In this study, an anti-Giardia IgG extracted from serum of contaminated rabbit was purified by ion-exchange chromatography and conjugated to the enzyme horse radish peroxidase (HRP). This antibody was used to design direct and indirect ELISA kits to measure conjugation titer. In both direct and indirect ELISA methods, optical densities (ODs) were 1 by using dilution of 1/4000 of conjugation. According to the results of both tests and the success in produced conjugate, it could be proceeded to prepare ELISA kits to diagnose giardiasis infections in various samples.Key words: Enzyme linked immunosorbent assay (ELISA), antibody, copro-antigen, Giardia lamblia
Impact of Exercise in Community-Dwelling Older Adults
Background: Concern has been expressed that preventive measures in older people might increase frailty by increasing survival without improving health. We investigated the impact of exercise on the probabilities of health improvement, deterioration and death in community-dwelling older people. Methods and Principal Findings: In the Canadian Study of Health and Aging, health status was measured by a frailty index based on the number of health deficits. Exercise was classified as either high or low/no exercise, using a validated, selfadministered questionnaire. Health status and survival were re-assessed at 5 years. Of 6297 eligible participants, 5555 had complete data. Across all grades of frailty, death rates for both men and women aged over 75 who exercised were similar to their peers aged 65 to 75 who did not exercise. In addition, while all those who exercised had a greater chance of improving their health status, the greatest benefits were in those who were more frail (e.g. improvement or stability was observed in 34 % of high exercisers versus 26 % of low/no exercisers for those with 2 deficits compared with 40 % of high exercisers versus 22 % of low/no exercisers for those with 9 deficits at baseline). Conclusions: In community-dwelling older people, exercise attenuated the impact of age on mortality across all grades of frailty. Exercise conferred its greatest benefits to improvements in health status in those who were more frail at baseline
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