6,213 research outputs found

    Simulation study of signal formation in position sensitive planar p-on-n silicon detectors after short range charge injection

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    Segmented silicon detectors (micropixel and microstrip) are the main type of detectors used in the inner trackers of Large Hadron Collider (LHC) experiments at CERN. Due to the high luminosity and eventual high fluence of energetic particles, detectors with fast response to fit the short shaping time of 20-25 ns and sufficient radiation hardness are required. Charge collection measurements carried out at the Ioffe Institute have shown a reversal of the pulse polarity in the detector response to short-range charge injection. Since the measured negative signal is about 30-60% of the peak positive signal, the effect strongly reduces the CCE even in non-irradiated detectors. For further investigation of the phenomenon the measurements have been reproduced by TCAD simulations. As for the measurements, the simulation study was applied for the p-on-n strip detectors similar in geometry to those developed for the ATLAS experiment and for the Ioffe Institute designed p-on-n strip detectors with each strip having a window in the metallization covering the p(+) implant, allowing the generation of electron-hole pairs under the strip implant. Red laser scans across the strips and the interstrip gap with varying laser diameters and Si-SiO2 interface charge densities (Q(f)) were carried out. The results verify the experimentally observed negative response along the scan in the interstrip gap. When the laser spot is positioned on the strip p(+) implant the negative response vanishes and the collected charge at the active strip increases respectively. The simulation results offer a further insight and understanding of the influence of the oxide charge density in the signal formation. The main result of the study is that a threshold value of Q(f), that enables negligible losses of collected charges, is defined. The observed effects and details of the detector response for different charge injection positions are discussed in the context of Ramo's theorem.Peer reviewe

    A comparison of the DNA binding and bending capacities and the oligomeric states of the immunity repressors of heteroimmune coliphages P2 and WPhi

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    Bacteriophages P2 and WΦ are heteroimmune members of the P2-like family of temperate Escherichia coli phages. Temperate phages can grow lytically or form lysogeny after infection. A transcriptional switch that contains two con-vergent promoters, Pe and Pc, and two repressors regulate what life mode to enter. The immunity repressor C is the first gene of the lysogenic operon, and it blocks the early Pe promoter. In this work, some characteristics of the C proteins of P2 and WΦ are compared. An in vivo genetic analysis shows that WΦ C, like P2 C, has a strong dimerization activity in the absence of its DNA target. Both C proteins recognize two directly repeated sequences, termed half-sites and a strong bending is induced in the respective DNA target upon binding. P2 C is unable to bind to one half-site as opposed to WΦ, but both half-sites are required for repression of WΦ Pe. A reduction from three to two helical turns between the centers of the half-sites in WΦ has no significant effect on the capacity to repress Pe. However, the protein–DNA complexes formed differ, as determined by electrophoretic mobility shift experiments. A difference in spontaneous phage production is observed in isogenic lysogens

    Genetics, recombination and clinical features of human rhinovirus species C (HRV-C) infections; interactions of HRV-C with other respiratory viruses

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    To estimate the frequency, molecular epidemiological and clinical associations of infection with the newly described species C variants of human rhinoviruses (HRV), 3243 diagnostic respiratory samples referred for diagnostic testing in Edinburgh were screened using a VP4-encoding region-based selective polymerase chain reaction (PCR) for HRV-C along with parallel PCR testing for 13 other respiratory viruses. HRV-C was the third most frequently detected behind respiratory syncytial virus (RSV) and adenovirus, with 141 infection episodes detected among 1885 subjects over 13 months (7.5%). Infections predominantly targeted the very young (median age 6–12 months; 80% of infections in those <2 years), occurred throughout the year but with peak incidence in early winter months. HRV-C was detected significantly more frequently among subjects with lower (LRT) and upper respiratory tract (URT) disease than controls without respiratory symptoms; HRV-C mono-infections were the second most frequently detected virus (behind RSV) in both disease presentations (6.9% and 7.8% of all cases respectively). HRV variants were classified by VP4/VP2 sequencing into 39 genotypically defined types, increasing the current total worldwide to 60. Through sequence comparisons of the 5′untranslated region (5′UTR), the majority grouped with species A (n = 96; 68%, described as HRV-Ca), the remainder forming a phylogenetically distinct 5′UTR group (HRV-Cc). Multiple and bidirectional recombination events between HRV-Ca and HRV-Cc variants and with HRV species A represents the most parsimonious explanation for their interspersed phylogeny relationships in the VP4/VP2-encoding region. No difference in age distribution, seasonality or disease associations was identified between HRV-Ca and HRV-Cc variants. HRV-C-infected subjects showed markedly reduced detection frequencies of RSV and other respiratory viruses, providing evidence for a major interfering effect of HRV-C on susceptibility to other respiratory virus infections. HRV-C's disease associations, its prevalence and evidence for interfering effects on other respiratory viruses mandates incorporation of rhinoviruses into future diagnostic virology screening

    Catheter-Directed Thrombolysis Versus Pharmacomechanical Thrombectomy for Upper Extremity Deep Venous Thrombosis : A Cost-Effectiveness Analysis

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    Background: Upper extremity deep vein thrombosis represents (UEDVT) 2-3% of all deep vein thrombosis. Catheter directed thrombolysis (CDT) was replaced largely by pharmacomechanical thrombolysis (PMT) in our institution. In this study we compared the immediate and 1-year results as well as the total hospital costs between CDT and PMT in the treatment of UEDVT. Methods: From 2006 to 2013, 55 patients with UEDVT were treated with either CDT or PMT at Helsinki University Hospital. Of them, 43 underwent thoracoscopic rib resection later to relieve phlebography-confirmed vein compression. This patient cohort was prospectively followed up with repeated phlebographies. CDT was performed to 24 patients, and 19 had PMT with a Trellis (TM) device. Clinical evaluation and vein patency assessment were performed with either phlebography or ultrasound 1 year after the thrombolysis. Primary outcomes were immediate technical success, 1-year vein patency, and costs of the initial treatment. Results: The immediate overall technical success rate, defined as recanalization of the occluded vein and removal of the fresh thrombus, was 91.7% in the CDT group and 100% in the PMT group (n.s.). The median thrombolytic time was significantly longer in CDT patients than that in PMT patients (21.1 vs. 0.33 hr, P <0.00001). There were no procedure-related complications. The 1-year primary assisted patency rate was similar in both the groups (91.7% and 94.7%). There were no recurrences of clinical DVT. The hospital costs for the acute period were significantly lower in the PMT group than those in the CDT group (medians: 11,476 (sic) and 5,975 (sic) in the CDT and PMT groups, respectively [P <0.00001]). Conclusions: The clinical results of the treatment of UEDVT with CDT or PMT were similar. However, PMT required shorter hospital stay and less intensive surveillance, leading to lower total costs.Peer reviewe

    Revealing sources of CH4 in a boreal upland forest

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    Overview of positioning technologies from fitness-to-purpose point of view

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    Even though Location Based Services (LBSs) are being more and more widely-used and this shows a promising future, there are still many challenges to deal with, such as privacy, reliability, accuracy, cost of service, power consumption and availability. There is still no single low-cost positioning technology which provides position of its users seamlessly indoors and outdoors with an acceptable level of accuracy and low power consumption. For this reason, fitness of positioning service to the purpose of LBS application is an important parameter to be considered when choosing the most suitable positioning technology for an LBS. This should be done for any LBS application, since each application may need different requirements. Some location-based applications, such as location-based advertisements or Location-Based Social Networking (LBSN), do not need very accurate positioning input data, while for some others, e.g. navigation and tracking services, highly-accurate positioning is essential. This paper evaluates different positioning technologies from fitness-to-purpose point of view for two different applications, public transport information and family/friend tracking

    Indoor positioning technology assessment using analytic hierarchy process for pedestrian navigation services

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    Indoor positioning is one of the biggest challenges of many Location Based Services (LBS), especially if the target users are pedestrians, who spend most of their time in roofed areas such as houses, offices, airports, shopping centres and in general indoors. Providing pedestrians with accurate, reliable, cheap, low power consuming and continuously available positional data inside the buildings (i.e. indoors) where GNSS signals are not usually available is difficult. Several positioning technologies can be applied as stand-alone indoor positioning technologies. They include Wireless Local Area Networks (WLAN), Bluetooth Low Energy (BLE), Ultra-Wideband (UWB), Radio Frequency Identification (RFID), Tactile Floor (TF), Ultra Sound (US) and High Sensitivity GNSS (HSGNSS). This paper evaluates the practicality and fitness-to-the-purpose of pedestrian navigation for these stand-alone positioning technologies to identify the best one for the purpose of indoor pedestrian navigation. In this regard, the most important criteria defining a suitable positioning service for pedestrian navigation are identified and prioritised. They include accuracy, availability, cost, power consumption and privacy. Each technology is evaluated according to each criterion using Analytic Hierarchy Process (AHP) and finally the combination of all weighted criteria and technologies are processed to identify the most suitable solution

    Night Awakening in Infancy : Developmental Stability and Longitudinal Associations With Psychomotor Development

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    Fragmented sleep is common in infancy. Although night awakening is known to decrease with age, in some infants night awakening is more persistent and continues into older ages. However, the influence of fragmented sleep on development is poorly known. In the present study, the longitudinal relationship between fragmented sleep and psychomotor development (Bayley Scales of Infant and Toddler Development [Bayley-III]; Bayley, 2009) was investigated in infants with (>= 3 night awakenings, n = 81) and without fragmented sleep (Peer reviewe
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