Overwintering aggregations of Leiobunum paessleri in caves and mines (Arachnida, Opiliones).

In the forested mountain areas of southwestern Canada, Leiobunull1 paessleri (Roewer) form overwintering aggregations in the twilight regions of moist caves and mines. Each aggregation consists of adults of both sexes and may contain as many as one or two thousand individuals. The opilionids congregate from August to October and disperse from April to May. Colder temperatures seem to increase the density of the aggregations. When dense aggregations are formed (up to 2.6 individuals per em'), the opilionids hang by their pedipalps with their legs extended straight down from their bodies. Explanations of the aggregation phenomenon include: optimal temperatures and humidities, reduced desiccation, heat production, increased mating success, and reduced predation. Overwintering mortality factors potentially include cold, desiccation, starvation, predation and disease

Some influences of area and pest management on apple mite populations in the Okanagan Valley of British Columbia

Biweekly leaf samples were taken from commercial apple orchards in four main growing areas, from north to south of the Okanagan Valley, each about 70 km apart, during the full growing season of 1983. Both phytophagous and predacious mite distribution and abundance were influenced by the area and four management practices. Unsprayed orchards had few mites, whereas regularly sprayed orchards tended to have larger mite populations, the species composition and abundance of which varied with area. The numbers of some species of phytophagous mites appeared to be related to the species and abundance of predacious mites present in a given orchard

Economic Integration

The results of international trade have generated a set of both winners and losers. On one side we have the big companies and big producers that stand out and on the other hand, there is a sector that has been affected such as groups of peasants, rural communities, cooperatives, amongst others that live in the poor southern countries. Therefore, the objective of this research article is the search and the design of mechanisms that will counteract the flaws of the current systems, and that will translate into social policies to give a solution to the more unprotected people. Fair trade is an alternative that is heading towards practices of a more social and solidary economy and through these mechanisms, that are funded in

Label-Free Impedimetric Aptasensor with Antifouling Surface Chemistry: a Prostate Specific Antigen Case Study

We here report the development of an aptamer based biosensor for the investigation of prostate specific antigen (PSA), a biomarker found in blood for prostate cancer (PCa), using electrochemical impedance spectroscopy (EIS). The study concentrates on a clinical application where a specific and sensitive label-free detection could be performed in real blood samples using EIS. Two types of PSA aptasensor were fabricated by immobilizing (i) a self-assembled monolayer comprising of 6-mercaptohexanol (MCH) and thiolated-DNA aptamer and (ii) 11-mercaptoundecanoic acid for covalent immobilization of amine terminated DNA aptamers and sulfo-betaine terminated thiol as an antifouling agent on a polycrystalline gold surface. Upon incubation of PSA with the DNA aptamer-based biosensor a decrease of charge transfer resistance (Rct) was observed due to the partial screening of the DNA aptamer charge by PSA. Thiol terminated sulfo-betaine based sensors can detect PSA levels lower than 1 ng/ml. Validation of the aptasensor is provided by surface plasmon resonance measurements. Sulfo-betaine moiety also prevents any significant non-specific binding of the control protein human serum albumin (HSA) as compared to high non-specific binding with MCH-based sensors. A debate is presented on the effect of the measurement buffer on the values and the direction of Rct changes on the aptasensors and the need to cautiously select suitable measurement conditions in order to obtain reliable results. This is the first report to date where a DNA aptamer-based biosensor was developed using thiol-terminated sulfo-betaine, which is a simple surface chemistry for the development of promising, cost-effective, label-free and sensitive electrochemical detection platforms for a range of analytes

Correlating electrochemical impedance spectroscopy and quartz crystal microbalance with dissipation signals for optimisation of aptamer-based biosensors

DNA aptamers provide new avenues towards the development of a wide range of biosensors with high specificity and controlled surface chemistry for signal optimisation. Electrochemical Impedance Spectroscopy (EIS) is an extremely promising technique towards the development of DNA-based biosensors since it can be used to accurately monitor changes in the charge density of the DNA layer. However, EIS optimisation for DNA aptamers is somewhat complex due to the different characteristics that induce a signal change: namely DNA density, change in charge density close to the electrode upon DNA conformational changes, size and charge of the analyte, screening of DNA charges upon analyte binding. The use of techniques such as Quartz Crystal Microbalance with Dissipation mode (QCM-D) can provide valuable information about conditions for maximum analyte binding as well as the hydration, folding and behaviour of the aptamer distribution on the electrode.We here report on the correlation of EIS and QCM-D signals for optimisation of aptamer-based biosensors using a DNA aptamer against Prostate Specific Antigen (PSA) as a case study. Given the unreliability of current prostate cancer diagnostic tools, it is critical to develop prostate cancer biosensors with high selectivity and sensitivity. Although PSA by itself is not an ideal prostate cancer biomarker, it is believed that any reliable diagnosis will involve a panel of biomarkers comprising PSA. The sensor setup comprises a gold surface modified with a mixed Self Assembled Monolayer (SAM) made of 6-mercapto-hexanol (MCH) and thiolated-DNA aptamer. QCM-D results provided the optimal MCH:aptamer ratios, pH and buffer solutions for the binding of PSA to the aptamers. The efficiencies of the two techniques under similar conditions were compared and correlated in order to develop a reliable, label-free and cost effective biosensor for prostate cancer as well as to serve as support for further EIS aptamer-based sensors

Reconstruction of primary vertices at the ATLAS experiment in Run 1 proton–proton collisions at the LHC

This paper presents the method and performance of primary vertex reconstruction in proton–proton collision data recorded by the ATLAS experiment during Run 1 of the LHC. The studies presented focus on data taken during 2012 at a centre-of-mass energy of √s=8 TeV. The performance has been measured as a function of the number of interactions per bunch crossing over a wide range, from one to seventy. The measurement of the position and size of the luminous region and its use as a constraint to improve the primary vertex resolution are discussed. A longitudinal vertex position resolution of about 30μm is achieved for events with high multiplicity of reconstructed tracks. The transverse position resolution is better than 20μm and is dominated by the precision on the size of the luminous region. An analytical model is proposed to describe the primary vertex reconstruction efficiency as a function of the number of interactions per bunch crossing and of the longitudinal size of the luminous region. Agreement between the data and the predictions of this model is better than 3% up to seventy interactions per bunch crossing

Linear electronics for Si-detectors and its energy calibration for use in heavy ion experiments

Abstract The design and implementation of linear electronics based on small-size, low-power charge preamplifiers and shaping amplifiers, used in connection with Si-detector telescopes employed in heavy ion experiments, are presented. Bench tests and "under beam" performances are discussed. In particular, the energy calibration and the linearity test of the overall system (Si-detector and linear and digital conversion electronics) has been performed with a procedure which avoids the pulse height defect problems connected with the detection of heavy ions. The procedure, basically, consists of using bursts of MeV protons, releasing up to GeV energies inside the detector, with low ionization density