Exclusive Electro-Disintegration of 3He at high Q2: II. Decay Function Formalism

Based on the theoretical framework of generalized eikonal approximation we study the two-nucleon emission reactions in high $Q^2$ electro-disintegration of $^3He$. Main aim is to investigate those features of the reaction which can be unambiguously identified with the short range properties of the ground state nuclear wave function. To evaluate the differential cross section we work in the formalism of the decay function which characterizes the property of the ground state wave function as well as the decay properties of final two nucleon spectator system. Our main motivation here is to explore the accessibility of two-- and three--nucleon short range correlations in $^3$He as well as to isolate unambiguously single and double rescattering processes in the reaction dynamics. Our analysis allowed us also to identify new approaches for investigating the role of the practically unknown three-nucleon forces in the ground state wave function of $^3He$.Comment: 37 pages, 28 figure

APEX: A Prime EXperiment at Jefferson Lab

APEX is an experiment at Thomas Jefferson National Accelerator Facility (JLab) in Virginia, USA, that searches for a new gauge boson ($A^\prime$) with sub-GeV mass and coupling to ordinary matter of $g^\prime \sim (10^{-6} - 10^{-2}) e$. Electrons impinge upon a fixed target of high-Z material. An $A^\prime$ is produced via a process analogous to photon bremsstrahlung, decaying to an $e^+ e^-$ pair. A test run was held in July of 2010, covering $m_{A^\prime}$ = 175 to 250 MeV and couplings g^\prime/e \; \textgreater \; 10^{-3}. A full run is approved and will cover $m_{A^\prime} \sim$ 65 to 525 MeV and g^\prime/e \; \textgreater \; 2.3 \times10^{-4}.Comment: Contributed to the 8th Patras Workshop on Axions, WIMPs and WISPs, Chicago, July 18-22, 2012. 4 pages, 4 figure

Risk factors of postoperative complications after radical cystectomy with continent or conduit urinary diversion in Armenia

To estimate the surgical volume and the incidence of in-hospital complications of RC in Armenia from 2005 to 2012, and to investigate potential risk factors of complications. The study utilized a retrospective chart review in a cohort of patients who had RC followed by either continent or conduit urinary diversion in all hospitals of Armenia from 2005 to 2012. A detailed chart review was conducted abstracting information on baseline demographic and clinical characteristics, surgical procedural details, postoperative management and in-hospital complications. Multivariable logistic regression analysis was applied to estimate the independent risk factors for developing ‘any postoperative complication’. The total study sample included 273 patients (mean age = 58.5 years, 93.4 % men). Overall, 28.9 % (n = 79) of patients had at least one in-hospital complication. The hospital mortality rate was 4.8 % (n = 13). The most frequent types of complications were wound-related (10.3 %), gastrointestinal (9.2 %) and infectious (7.0 %). The ischemic heart disease (OR = 3.3, 95 % CI 1.5–7.4), perioperative transfusion (OR = 2.0, 1.1–3.6), glucose level [OR = 0.71 (0.63–0.95)], and hospital type (OR = 2.3, 95 % CI 1.1–4.7) were independent predictors of postoperative complications. The rate of RC complications in Armenia was similar to those observed in other countries. Future prospective studies should evaluate the effect of RC complications on long-term outcomes and costs in Armenia. Policy recommendations should address the issues regarding surgeon training and hospital volume to decrease the risk of RC complications

Automatic multi-camera extrinsic parameter calibration based on pedestrian torsors

Extrinsic camera calibration is essential for any computer vision task in a camera network. Typically, researchers place a calibration object in the scene to calibrate all the cameras in a camera network. However, when installing cameras in the field, this approach can be costly and impractical, especially when recalibration is needed. This paper proposes a novel, accurate and fully automatic extrinsic calibration framework for camera networks with partially overlapping views. The proposed method considers the pedestrians in the observed scene as the calibration objects and analyzes the pedestrian tracks to obtain extrinsic parameters. Compared to the state of the art, the new method is fully automatic and robust in various environments. Our method detect human poses in the camera images and then models walking persons as vertical sticks. We apply a brute-force method to determines the correspondence between persons in multiple camera images. This information along with 3D estimated locations of the top and the bottom of the pedestrians are then used to compute the extrinsic calibration matrices. We also propose a novel method to calibrate the camera network by only using the top and centerline of the person when the bottom of the person is not available in heavily occluded scenes. We verified the robustness of the method in different camera setups and for both single and multiple walking people. The results show that the triangulation error of a few centimeters can be obtained. Typically, it requires less than one minute of observing the walking people to reach this accuracy in controlled environments. It also just takes a few minutes to collect enough data for the calibration in uncontrolled environments. Our proposed method can perform well in various situations such as multi-person, occlusions, or even at real intersections on the street

Automatic extrinsic calibration of camera networks based on pedestrians

Extrinsic camera calibration is essential for any computer vision tasks in a camera network. Usually, researchers place calibration objects in the scene to calibrate the cameras. However, when installing cameras in the field, this approach can be costly and impractical, especially when recalibration is needed. This paper proposes a novel accurate and fully automatic extrinsic calibration framework for camera networks with partially overlapping views. It is based on the analysis of pedestrian tracks without other calibration objects. Compared to the state of the art, the new method is fully automatic and robust. Our method detects human poses in the camera images and then models walking persons as vertical sticks. We propose a brute-force method to determine the pedestrian correspondences in multiple camera images. This information along with 3D estimated locations of the head and feet of the pedestrians are then used to compute the camera extrinsic matrices. We verified the robustness of the method in different camera setups and for both single pedestrian and multiple walking people. The results show that the proposed method can obtain the triangulation error of a few centimeters. Typically, it requires 40 seconds of collecting data from walking people to reach this accuracy in controlled environments and a few minutes for uncontrolled environments. As well as compute relative extrinsic parameters connecting the coordinate systems of cameras in a pairwise fashion automatically. Our proposed method could perform well in various situations such as multi-person, occlusions, or even at real intersections on the street

On the Mechanisms of Transcranial Magnetic Stimulation (TMS): How Brain State and Baseline Performance Level Determine Behavioral Effects of TMS

The behavioral effects of Transcranial Magnetic Stimulation (TMS) can change qualitatively when stimulation is preceded by initial state manipulations such as priming or adaptation. In addition, baseline performance level of the participant has been shown to play a role in modulating the impact of TMS. Here we examined the link between these two factors. This was done using data from a previous study using a TMS-priming paradigm, in which, at group level, TMS selectively facilitated targets incongruent with the prime while having no statistically significant effects on other prime-target congruencies. Correlation and linear mixed-effects analyses indicated that, for all prime-target congruencies, a significant linear relationship between baseline performance and the magnitude of the induced TMS effect was present: low levels of baseline performance were associated with TMS-induced facilitations and high baseline performance with impairments. Thus as performance level increased, TMS effects turned from facilitation to impairment. The key finding was that priming shifted the transition from facilitatory to disruptive effects for targets incongruent with the prime, such that TMS-induced facilitations were obtained until a higher level of performance than for other prime-target congruencies. Given that brain state manipulations such as priming operate via modulations of neural excitability, this result is consistent with the view that neural excitability, coupled with non-linear neural effects, underlie behavioral effects of TMS

Adaptable history biases in human perceptual decisions

When making choices under conditions of perceptual uncertainty, past experience can play a vital role. However, it can also lead to biases that worsen decisions. Consistent with previous observations, we found that human choices are influenced by the success or failure of past choices even in a standard two-alternative detection task, where choice history is irrelevant. The typical bias was one that made the subject switch choices after a failure. These choice history biases led to poorer performance and were similar for observers in different countries. They were well captured by a simple logistic regression model that had been previously applied to describe psychophysical performance in mice. Such irrational biases seem at odds with the principles of reinforcement learning, which would predict exquisite adaptability to choice history. We therefore asked whether subjects could adapt their irrational biases following changes in trial order statistics. Adaptability was strong in the direction that confirmed a subject's default biases, but weaker in the opposite direction, so that existing biases could not be eradicated. We conclude that humans can adapt choice history biases, but cannot easily overcome existing biases even if irrational in the current context: adaptation is more sensitive to confirmatory than contradictory statistics

A study of the prevalence of antibodies to Epstein-Barr virus in a large cohort of patients with early multiple sclerosis

Hintergrund: Die Multiple Sklerose (MS) ist eine entzündliche Erkrankung des zentralen Nervensystems (ZNS), die auf dem Boden einer Interaktion von genetischen und Umweltfaktoren entsteht. Der wichtigste und stärkste derzeit bekannte externe Risikofaktor für die Entwicklung einer MS ist eine Infektion mit dem Epstein-Barr-Virus (EBV). Frühere seroepidemiologische Untersuchungen haben übereinstimmend gezeigt, dass fast alle Patienten mit MS EBV-seropositiv sind. Sollte eine Infektion mit EBV tatsächlich eine Voraussetzung zur Entwicklung einer MS sein, wäre jedoch zu erwarten, dass Patienten mit MS ausnahmslos EBV-seropositiv sind. Somit stellt sich die Frage, ob es wirklich EBV-seronegative Patienten mit einer MS gibt. Zielsetzung: Zielsetzung der vorliegenden Arbeit war die Bestimmung der Seroprävalenz von Antikörpern gegen das EBV in einer großen Kohorte von Patienten mit früher MS. Methodik: In Serumproben von 901 Patienten mit einem klinisch isolierten Syndrom (KIS, der klinischen Erstmanifestation einer MS) oder schubförmiger MS aus der deutschen nationalen MS-Kohorte wurden IgG-Antikörper gegen das Epstein-Barr nukleäre Antigen-1 (EBNA-1) mit einem Chemilumineszenz-Immunoassay (CLIA) gemessen. Antikörper gegen das EBV viral capsid antigen (VCA) wurden bei EBNA-1-Antikörper-seronegativen Patienten ebenfalls mittels CLIA analysiert. EBNA-1- und VCA-Antikörper-seronegative Patienten wurden mit einem EBV-IgG-Immunoblot untersucht. Zur Ermittlung der EBV-Seroprävalenz in einer Kontrollpopulation wurde in einer großen Krankenhauspopulation (n=16.163) aus Berlin/Norddeutschland die EBV-Seroprävalenz in unterschiedlichen Altersgruppen von 80 Jahren ermittelt. Ergebnisse: Von 901 Patienten mit KIS/RRMS hatten 839 IgG-Antikörper gegen EBNA-1. IgG-Antikörper gegen VCA wurden bei 45 von 62 EBNA-1-Antikörper seronegativen Patienten nachgewiesen. Unter Verwendung von EBV-IgG-Immunoblots wurden bei allen übrigen 17 Patienten IgG-Antikörper gegen EBV gefunden. Somit waren alle 901 Patienten (100%) mit KIS/RRMS, die in unsere Studie eingeschlossen wurden, seropositiv für EBV. Die EBV-Seroprävalenz in der Krankenhauspopulation stieg mit zunehmendem Alter in allen 5-Jahres-Alterskohorten an, erreichte aber in keiner der untersuchten Altersgruppen 100%. Schlussfolgerungen: Die Abwesenheit von EBV-seronegativen Personen in dieser gut charakterisierten Kohorte von Patienten mit früher MS weist auf eine zentrale Rolle von EBV bei der MS hin. Eine negative EBV-Serologie bei Patienten mit Verdacht auf eine entzündliche Erkrankung des ZNS spricht gegen eine MS und sollte anderweitige Diagnosen in Betracht ziehen lassen.Background: Multiple Sclerosis (MS) is an inflammatory disease of the central nervous system, which develops through an interaction of genetic and environmental factors. Epstein-Barr virus (EBV) is the most important and strongest currently known risk factor for MS. Previous seroepidemiological studies have consistently shown that almost all patients with MS are EBV-seropositive. However, if EBV infection was indeed a prerequisite for development of MS, one would expect that all patients with MS (100%) would be EBV seropositive. The question therefore arises whether EBV seronegative patients with MS do really exist. Objective: The present study aimed to determine the seroprevalence of antibodies against EBV in a large cohort of patients with early MS. Methods: In serum samples from 901 patients with a clinically isolated syndrome (CIS, the first clinical manifestation of multiple sclerosis) or with early relapsing-remitting MS (RRMS) from the German National MS cohort antibodies to Epstein-Barr nuclear antigen-1 (EBNA-1) were measured by a chemiluminescence immunoassay (CLIA). Antibodies to the EBV viral capsid antigen (VCA) were analyzed in EBNA-1 antibody seronegative patients by CLIA as well. EBV IgG immunoblot was used to analyze EBNA-1 and VCA antibody seronegative patients. To determine the EBV seroprevalence in a control population, we determined the EBV seroprevalence in different age groups ranging from 80 years in a large hospital population (n = 16,163) from Berlin/Northern Germany. Results: Of the 901 patients with CIS/RRMS, 839 had IgG antibodies to EBNA-1. IgG antibodies to VCA were detected in 45 of 62 EBNA-1 antibody seronegative patients. Using EBV IgG immunoblots, IgG antibodies to EBV were found among all the remaining 17 patients. Therefore, all 901 patients (100%) with CIS/RRMS included in our study were seropositive for EBV. EBV seropositivity increased with increasing age in the hospital population, but did not reach 100% in any of the examined age groups. Conclusions: The absence of EBV seronegativity in this well-characterized cohort of patients with early MS indicates a central role of EBV in MS. EBV seronegativity in patients with suspected inflammatory central nervous system diseases should alert clinicians to take into account diagnoses other than MS