2,709 research outputs found

    NewOX - extending the online exXam system to provide automated formative evaluation of student text-based assignments

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    A cheat-resistant and foolproof distributed electronic application for summativeassessment of student learning outcomes has been developed and field tested "OnlineeXam" (OX). Good usability experience and feedback features for the students as wellas the lecturers were design goals of the implementation. The field tests showed therobustness of the system in a heterogenic PC pool environment, the ease of use and agood student learning outcome assessment ability (summative assessment) but a lackof a formative impact on the student learning efforts. The incorporation and adoption(for European needs) of a short essay assessment algorithm with a rich user interfaceis proposed

    Subthreshold laser therapy with a standardized macular treatment pattern in chronic central serous chorioretinopathy

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    PURPOSE There is an ongoing controversial debate about the effectiveness of laser treatments in chronic central serous chorioretinopathy (cCSC). We performed a prospective non-randomized interventional study to learn about the effects of a subthreshold laser treatment (Topcon Endpoint Management™, Topcon Healthcare Inc., Tokyo, Japan) in patients with cCSC. METHODS Patients with cCSC and a minimum symptom duration of 4~months were included and treated with a standardized laser pattern covering the macular area. Retreatment was performed every 3~months if persistent subretinal fluid was observed. The primary endpoint was resolution of subretinal fluid at 6~months. Further outcome parameters included best corrected visual acuity, microperimetry, central macular and subfoveal choroidal thickness. RESULTS A total of 42 eyes of 39 patients were included. Mean patient age was 48 ± 10.6~years (range 25-67). Mean symptomatic time before inclusion into the study was 134 ± 133.4~weeks (16-518). Before inclusion, 78.6% of the patients had failed to resolve subretinal fluid under mineralocorticoid receptor antagonists and 14.3% had a recurrence after half-dose photodynamic therapy. Complete resolution of subretinal fluid was observed in 42.9% at 6~months and in 53.8% at 12~months after baseline. Central retinal thickness decreased from 398 ± 135~µm to 291 ± 68~µm (p < 0.001), subfoveal choroidal thickness changed slightly (430 ± 116~µm to 419 ± 113~µm, p = 0.026), microperimetry-derived macular function improved by 19.1 ± 4.7~dB to 21.3 ± 4.8~dB (p = 0.008) and mean BCVA improved by 4.9 ± 8.6 ETDRS letters (p < 0.001). CONCLUSION The results show that the investigated laser treatment is effective in reducing subretinal fluid and leads to an improvement of functional parameters

    Ranibizumab non-response in pachychoroid neovasculopathy: Effects of switching to aflibercept

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    Non-response to intravitreal ranibizumab represents a frequent problem in pachychoroid neovasculopathy (PNV). To investigate the effectivity of switching to aflibercept, the database of the Ludwig Maximilians University, Munich, was screened for patients fulfilling the following inclusion criteria: (i) diagnosis of PNV;(ii) inadequate response to >= 3 ranibizumab injections, in spite of monthly dosing, defined as persistence of subretinal-fluid four weeks after the last ranibizumab injection;(iii) resulting switch to aflibercept administered as three monthly injections. Primary outcome measure was percentage of eyes with a dry macula four weeks after the third aflibercept injection. Secondary outcome measures included changes in maximum subretinal fluid (SRF), central subfield thickness (CST) and subfoveal choroidal thickness (SFCT). In total, 14 eyes of 14 patients were included. Mean age was 64.1 +/- 7.5 (range: 51-78) years. Switching to aflibercept was performed after mean 8.4 +/- 4.1 (3-15) ranibizumab injections. While no eye (0%) achieved a dry macula status during ranibizumab treatment, switching to aflibercept achieved a dry macula status in eight eyes (57.1%) after three injections. While both ranibizumab and aflibercept showed an effect on CST (p=0.027, p=0.003), only aflibercept showed a significant effect on SRF (p=0.0009) and SFCT (p=0.044). In cases of PNV not responding to intravitreal ranibizumab, switching treatment to aflibercept induces a favorable short-term response resolving persistent fluid and achieving a dry macula. Further studies with longer follow-up are warranted

    Vanishing pachy-choroid in pachychoroid neovasculopathy under long-term anti-vascular endothelial growth factor therapy

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    BACKGROUND To investigate the diagnostic value of choroidal thickness in the definition of pachychoroid neovasculopathy (PNV), especially in eyes treated with anti-vascular endothelial growth factor (VEGF) therapy. METHODS Twenty-two consecutive eyes of 11 patients with uni- or bilateral PNV were analyzed. Anti-VEGF treatment was correlated with changes in choroidal thickness on enhanced depth imaging optical coherence tomography. RESULTS There were 14 eyes with PNV and 8 non-neovascular partner eyes. Mean age was 64.2 ± 4.0 (range: 60-72), total follow-up was 1.8 ± 0.4 (1-2) years. In PNV eyes, choroidal thickness at baseline was 400 ± 58 (269-485) μm. After two years and 13 anti-VEGF injections on average, a mean reduction of - 39 ± 10 (- 26 to - 56) % to final 241 ± 52 (162-327) μm was observed (p~ 0.13 for all comparisons). A significant correlation of choroidal thinning and anti-VEGF injection rate was observed at year one (r = - 0.79; R2~= 0.63; p~= 0.00073) and two (r = - 0.69; R2~= 0.48; p~= 0.019). While 85.7% of PNV eyes exceeded a pachychoroid threshold of ≥350 μm at baseline, this figure dropped to 21.4% at year one and 0% at year two. CONCLUSION In PNV, choroidal thickness significantly decreases with anti-VEGF therapy, resembling a \textquotedblvanishing pachy-choroid\textquotedbl, and thus does not represent a valid long-term diagnostic criterium, especially when differentiating PNV from nAMD

    Longitudinal validity of spirometers--a challenge in longitudinal studies.

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    Pulmonary function testing (PFT) in longitudinal studies involves the repeated use of spirometers over long time periods. We assess the comparability of PFT results taken under biologic field conditions using thirteen certified devices of various technology and age. Comparability of measurements across devices and over time is relevant both in clinical and epidemiological research. Forced Vital Capacity (FVC), Forced Expiratory Volume in the first second (FEV1) and Forced Expiratory Flow 50% (FEF50) were compared before and after the data collection of the Swiss Study on Air Pollution and Lung Diseases in Adults (SAPALDIA) and the European Community Respiratory Health Survey (ECRHS) cohort studies. Three test series were conducted with 46, 50 and 56 volunteers using various combinations of spirometers to compare the eight flow-sensing spirometers (Sensormedics 2200) used in the SAPALDIA cross-sectional and follow-up, two new flow-sensing instruments (Sensormedics Vmax) and three volume displacement spirometers (two Biomedin/Baires and one Sensormedics 2400). The initial comparison (1999/2000) of eight Sensormedics 2200 and the follow-up comparison (2003) of the same devices revealed a maximal variation of up to 2.6% for FVC, 2.4% for FEV1 and 2.8% for FEF50 across devices with no indication of systematic differences between spirometers. Results were also reproducible between Biomedin, Sensormedics 2200 and 2400. The new generation of Sensormedics (Vmax) gave systematically lower results. The study demonstrates the need to conduct spirometer comparison tests with humans. For follow-up studies we strongly recommend the use of the same spirometers

    Cross-sectional associations between air pollution and chronic bronchitis: an ESCAPE meta-analysis across five cohorts

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    BACKGROUND: This study aimed to assess associations of outdoor air pollution on prevalence of chronic bronchitis symptoms in adults in five cohort studies (Asthma-E3N, ECRHS, NSHD, SALIA, SAPALDIA) participating in the European Study of Cohorts for Air Pollution Effects (ESCAPE) project. METHODS: Annual average particulate matter (PM10, PM2.5, PMabsorbance, PMcoarse), NO2, nitrogen oxides (NOx) and road traffic measures modelled from ESCAPE measurement campaigns 2008-2011 were assigned to home address at most recent assessments (1998-2011). Symptoms examined were chronic bronchitis (cough and phlegm for &ge;3 months of the year for &ge;2 years), chronic cough (with/without phlegm) and chronic phlegm (with/without cough). Cohort-specific cross-sectional multivariable logistic regression analyses were conducted using common confounder sets (age, sex, smoking, interview season, education), followed by meta-analysis. RESULTS: 15 279 and 10 537 participants respectively were included in the main NO2 and PM analyses at assessments in 1998-2011. Overall, there were no statistically significant associations with any air pollutant or traffic exposure. Sensitivity analyses including in asthmatics only, females only or using back-extrapolated NO2 and PM10 for assessments in 1985-2002 (ECRHS, NSHD, SALIA, SAPALDIA) did not alter conclusions. In never-smokers, all associations were positive, but reached statistical significance only for chronic phlegm with PMcoarse OR 1.31 (1.05 to 1.64) per 5 &micro;g/m(3) increase and PM10 with similar effect size. Sensitivity analyses of older cohorts showed increased risk of chronic cough with PM2.5abs (black carbon) exposures. CONCLUSIONS: Results do not show consistent associations between chronic bronchitis symptoms and current traffic-related air pollution in adult European populations

    Charged Particle Production in Proton-, Deuteron-, Oxygen- and Sulphur-Nucleus Collisions at 200 GeV per Nucleon

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    The transverse momentum and rapidity distributions of net protons and negatively charged hadrons have been measured for minimum bias proton-nucleus and deuteron-gold interactions, as well as central oxygen-gold and sulphur-nucleus collisions at 200 GeV per nucleon. The rapidity density of net protons at midrapidity in central nucleus-nucleus collisions increases both with target mass for sulphur projectiles and with the projectile mass for a gold target. The shape of the rapidity distributions of net protons forward of midrapidity for d+Au and central S+Au collisions is similar. The average rapidity loss is larger than 2 units of rapidity for reactions with the gold target. The transverse momentum spectra of net protons for all reactions can be described by a thermal distribution with `temperatures' between 145 +- 11 MeV (p+S interactions) and 244 +- 43 MeV (central S+Au collisions). The multiplicity of negatively charged hadrons increases with the mass of the colliding system. The shape of the transverse momentum spectra of negatively charged hadrons changes from minimum bias p+p and p+S interactions to p+Au and central nucleus-nucleus collisions. The mean transverse momentum is almost constant in the vicinity of midrapidity and shows little variation with the target and projectile masses. The average number of produced negatively charged hadrons per participant baryon increases slightly from p+p, p+A to central S+S,Ag collisions.Comment: 47 pages, submitted to Z. Phys.

    The ALICE TPC, a large 3-dimensional tracking device with fast readout for ultra-high multiplicity events

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    The design, construction, and commissioning of the ALICE Time-Projection Chamber (TPC) is described. It is the main device for pattern recognition, tracking, and identification of charged particles in the ALICE experiment at the CERN LHC. The TPC is cylindrical in shape with a volume close to 90 m^3 and is operated in a 0.5 T solenoidal magnetic field parallel to its axis. In this paper we describe in detail the design considerations for this detector for operation in the extreme multiplicity environment of central Pb--Pb collisions at LHC energy. The implementation of the resulting requirements into hardware (field cage, read-out chambers, electronics), infrastructure (gas and cooling system, laser-calibration system), and software led to many technical innovations which are described along with a presentation of all the major components of the detector, as currently realized. We also report on the performance achieved after completion of the first round of stand-alone calibration runs and demonstrate results close to those specified in the TPC Technical Design Report.Comment: 55 pages, 82 figure

    Software environment for controlling and re-configuration of Xilinx Virtex FPGAs – TWEPP-07

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    The Time Projection Chamber is one of the detectors of the ALICE experiment, that is currently being commissioned at the Large Hadron Collider at CERN. The Detector Control System is used for control and monitoring of the system. For the TPC Front-End Electronics (FEE) the control node is a Readout Control Unit that communicates to higher layers via Ethernet, using the standard framework DIM. The Readout Control Unit is equipped with commercial SRAM based FPGAs that will experience errors due to the radiation environment they are operating in. This article will present the implemented hardware solution for error correction and will focus on the software environment for configuration and controlling of the system – TWEPP-07
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