313 research outputs found
Gravitational-Wave Stochastic Background Detection with Resonant-Mass Detectors
In this paper we discuss how the standard optimal Wiener filter theory can be
applied, within a linear approximation, to the detection of an isotropic
stochastic gravitational-wave background with two or more detectors. We apply
then the method to the AURIGA-NAUTILUS pair of ultra low temperature bar
detectors, near to operate in coincidence in Italy, obtaining an estimate for
the sensitivity to the background spectral density of $\simeq 10^{-49}\
Hz^{-1}\simeq 8\times10^{-5}\times\rho_c\rho_c\simeq1.9 \times 10^{-26}\
kg/m^3\simeq 6
\times10^{-5}\times\rho_c\simeq 2\times10^{-5}\times
\rho_c\simeq 2 \times10^{-6}\rho_c$.Comment: 32 pages, postscript file, also available at
http://axln01.lnl.infn.it/reports/stoch.htm
Acentric Polymeric Chains in Radical Cation Salts of Tetrathiafulvalene Derivatives with the p-Carboxybenzenesulfonate Anion
The noncentrosymmetric p-carboxybenzenesulfonate anion afforded, in electro-oxidation experiments with bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF), the low-gap semiconductor (room-temperature conductivity: 18 S cmâ1) mixed-valency salt BEDT-TTF2[O3S-C6H4-CO2H], which is noncentrosymmetric due to head-to-tail arrangement of the anions, whereas EDT-TTF-CONHMe (EDT-TTF = ethylenedithiotetrathiafulvalene) afforded the fully oxidized centrosymmetric salt [EDT-TTF-CONHMe+][HO2C-C6H4-SO3â] in which the driving force for the crystal packing is the existence of strong hydrogen-bonding interactions between the anions and the amido groups of the cations
Rapid Detection of the H275Y Oseltamivir Resistance Mutation in Influenza A/H1N1 2009 by Single Base Pair RT-PCR and High-Resolution Melting
Introduction: We aimed to design a real-time reverse-transcriptase-PCR (rRT-PCR), high-resolution melting (HRM) assay to detect the H275Y mutation that confers oseltamivir resistance in influenza A/H1N1 2009 viruses.Findings: A novel strategy of amplifying a single base pair, the relevant SNP at position 823 of the neuraminidase gene, was chosen to maintain specificity of the assay. Wildtype and mutant virus were differentiated when using known reference samples of cell-cultured virus. However, when dilutions of these reference samples were assayed, amplification of nonspecific primer-dimer was evident and affected the overall melting temperature (Tm) of the amplified products. Due to primer-dimer appearance at .30 cycles we found that if the cycle threshold (CT) for a dilution was .30, the HRM assay did not consistently discriminate mutant from wildtype. Where the CT was ,30 we noted an inverse relationship between CT and Tm and fitted quadratic curves allowed the discrimination of wildtype, mutant and 30:70 mutant:wildtype virus mixtures. We compared the CT values for a TaqMan H1N1 09 detection assay with those for the HRM assay using 59 clinical samples and demonstrated that samples with a TaqMan detection assay CT.32.98 would have an H275Y assay CT.30. Analysis of the TaqMan CT values for 609 consecutive clinical samples predicted that 207 (34%) of the samples would result in an HRM assay CT.30 and therefore not be amenable to the HRM assay.Conclusions: The use of single base pair PCR and HRM can be useful for specifically interrogating SNPs. When applied to H1N1 09, the constraints this placed on primer design resulted in amplification of primer-dimer products. The impact primer-dimer had on HRM curves was adjusted for by plotting Tm against CT. Although less sensitive than TaqMan assays, the HRM assay can rapidly, and at low cost, screen samples with moderate viral concentrations
Approaches to identify the value of seminatural habitats for conservation biological control
Invertebrates perform many vital functions in agricultural production, but many taxa are in decline, including pest natural enemies. Action is needed to increase their abundance if more sustainable agricultural systems are to be achieved. Conservation biological control (CBC) is a key component of integrated pest management yet has failed to be widely adopted in mainstream agriculture. Approaches to improving conservation biological control have been largely ad hoc. Two approaches are described to improve this process, one based upon pest natural enemy ecology and resource provision while the other focusses on the ecosystem service delivery using the QuESSA (Quantification of Ecological Services for Sustainable Agriculture) project as an example. In this project, a predictive scoring system was developed to show the potential of five seminatural habitat categories to provide biological control, from which predictive maps were generated for Europe. Actual biological control was measured in a series of case studies using sentinel systems (insect or seed prey), trade-offs between ecosystem services were explored, and heatmaps of biological control were generated. The overall conclusion from the QuESSA project was that results were context specific, indicating that more targeted approaches to CBC are needed. This may include designing new habitats or modifying existing habitats to support the types of natural enemies required for specific crops or pests
CtGEM typing: Discrimination of Chlamydia trachomatis ocular and urogenital strains and major evolutionary lineages by high resolution melting analysis of two amplified DNA fragments
© 2018 Giffard et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Chlamydia trachomatis infects the urogenital tract (UGT) and eyes. Anatomical tropism is correlated with variation in the major outer membrane protein encoded by ompA. Strains possessing the ocular ompA variants A, B, Ba and C are typically found within the phyloge-netically coherent âclassical ocular lineageâ. However, variants B, Ba and C have also been found within three distinct strains in Australia, all associated with ocular disease in children and outside the classical ocular lineage. CtGEM genotyping is a method for detecting and discriminating ocular strains and also the major phylogenetic lineages. The rationale was facilitation of surveillance to inform responses to C. trachomatis detection in UGT specimens from young children. CtGEM typing is based on high resolution melting analysis (HRMA) of two PCR amplified fragments with high combinatorial resolving power, as defined by computerised comparison of 65 whole genomes. One fragment is from the hypothetical gene defined by Jali-1891 in the C. trachomatis B_Jali20 genome, while the other is from ompA. Twenty combinatorial CtGEM types have been shown to exist, and these encompass unique genotypes for all known ocular strains, and also delineate the TI and T2 major phylogenetic lineages, identify LGV strains and provide additional resolution beyond this. CtGEM typing and Sanger sequencing were compared with 42 C. trachomatis positive clinical specimens, and there were no disjunctions. CtGEM typing is a highly efficient method designed and tested using large scale comparative genomics. It divides C. trachomatis into clinically and biologically meaningful groups, and may have broad application in surveillance
Long-term field-realistic exposure to a next-generation pesticide, flupyradifurone, impairs honey bee behaviour and survival
10openInternationalInternational coauthor/editorThe assessment of pesticide risks to insect pollinators have typically focused on short-term, lethal impacts. The environmental ramifications of many of the worldâs most commonly employed pesticides, such as those exhibiting systemic properties that can result in long-lasting exposure to insects, may thus be severely underestimated. Here, seven laboratories from Europe and North America performed a standardised experiment (a ring-test) to study the long-term lethal and sublethal impacts of the relatively recently approved âbee safeâ butenolide pesticide flupyradifurone (FPF, active ingredient in SivantoÂź) on honey bees. The emerging contaminant, FPF, impaired bee survival and behaviour at field-realistic doses (down to 11âng/bee/day, corresponding to 400â”g/kg) that were up to 101-fold lower than those reported by risk assessments (1110âng/bee/day), despite an absence of time-reinforced toxicity. Our findings raise concerns about the chronic impact of pesticides on pollinators at a global scale and support a novel methodology for a refined risk assessmentopenTosi, Simone; Nieh, James C; Brandt, Annely; Colli, Monica; Fourrier, Julie; Giffard, Herve; HernĂĄndez-LĂłpez, Javier; Malagnini, Valeria; Williams, Geoffrey R; Simon-Delso, NoaTosi, S.; Nieh, J.C.; Brandt, A.; Colli, M.; Fourrier, J.; Giffard, H.; HernĂĄndez-LĂłpez, J.; Malagnini, V.; Williams, G.R.; Simon-Delso, N
Chlamydia trachomatis genotypes in a cross-sectional study of urogenital samples from remote Northern and Central Australia
his is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/Abstract
OBJECTIVES:
The objective was to determine the frequency of trachoma genotypes of Chlamydia trachomatis-positive urogenital tract (UGT) specimens from remote areas of the Australian Northern Territory (NT).
SETTING:
The setting was analysis of remnants of C. trachomatis positive primarily UGT specimens obtained in the course of clinical practice. The specimens were obtained from two pathology service providers.
PARTICIPANTS:
From 3356 C. trachomatis specimens collected during May 2012-April 2013, 439 were selected for genotyping, with a focus on specimens from postpubescent patients, in remote Aboriginal communities where ocular trachoma is potentially present.
PRIMARY AND SECONDARY OUTCOME MEASURES:
The primary outcome measure was the proportion of successfully genotyped UGT specimens that were trachoma genotypes. The secondary outcome measures were the distribution of genotypes, and the frequencies of different classes of specimens able to be genotyped.
RESULTS:
Zero of 217 successfully genotyped UGT specimens yielded trachoma genotypes (95% CI for frequency=0-0.017). For UGT specimens, the genotypes were E (41%), F (22%), D (21%) and K (7%), with J, H and G and mixed genotypes each at 1-4%. Four of the five genotyped eye swabs yielded trachoma genotype Ba, and the other genotype J. Two hundred twenty-two specimens (50.6%) were successfully genotyped. Urine specimens were less likely to be typable than vaginal swabs (p<0.0001).
CONCLUSIONS:
Unlike in some other studies, in the remote NT, trachoma genotypes of C. trachomatis were not found circulating in UGT specimens from 2012 to 2013. Therefore, C. trachomatis genotypes in UGT specimens from young children can be informative as to whether the organism has been acquired through sexual contact. We suggest inclusion of C. trachomatis genotyping in guidelines examining the source of sexually transmitted infections in young children in areas where trachoma genotypes may continue to circulate, and continued surveillance of UGT C. trachomatis genotypes
Detectability of gravitational wave events by spherical resonant-mass antennas
We have calculated signal-to-noise ratios for eight spherical resonant-mass
antennas interacting with gravitational radiation from inspiralling and
coalescing binary neutron stars and from the dynamical and secular bar-mode
instability of a rapidly rotating star. We find that by using technology that
could be available in the next several years, spherical antennas can detect
neutron star inspiral and coalescence at a distance of 15 Mpc and the dynamical
bar-mode instability at a distance of 2 Mpc.Comment: 39 pages, 4 EPS Figures, some additional SNRs for secular
instabilities, some changes to LIGO SNRs, Appendix added on the asymptotic
expansion of energy sensitivity, corrected supernova rates. Results available
at http://www.physics.umd.edu/rgroups/gen_rel_exp/snr.html Submitted to Phys.
Rev.
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