12,495 research outputs found

    LArGe: Background suppression using liquid argon (LAr) scintillation for 0νββ\nu\beta\beta decay search with enriched germanium (Ge) detectors

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    Measurements with a bare p-type high purity germanium diode (HPGe) submerged in a 19 kg liquid argon (LAr) scintillation detector at MPIK Heidelberg are reported. The liquid argon--germanium system (LArGe) is operated as a 4π\pi anti-Compton spectrometer to suppress backgrounds in the HPGe. This R&D is carried out in the framework of the GERDA experiment which searches for 0νββ\nu\beta\beta decays with HPGe detectors enriched in 76^{76}Ge. The goal of this work is to develop a novel method to discriminate backgrounds in 0νββ\nu\beta\beta search which would ultimately allow to investigate the effective neutrino mass free of background events down to the inverse mass hierarchy scale. Other applications in low-background counting are expected.Comment: 3 pages, 6 figures, conference proceedings of the 10th Topical Seminar on Innovative Particle and Radiation Detectors (IPRD06) 1 - 5 October 2006 Siena, Ital

    Technical quality assessment of an optoelectronic system for movement analysis

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    The Optoelectronic Systems (OS) are largely used in gait analysis to evaluate the motor performances of healthy subjects and patients. The accuracy of marker trajectories reconstruction depends on several aspects: the number of cameras, the dimension and position of the calibration volume, and the chosen calibration procedure. In this paper we propose a methodology to evaluate the eects of the mentioned sources of error on the reconstruction of marker trajectories. The novel contribution of the present work consists in the dimension of the tested calibration volumes, which is comparable with the ones normally used in gait analysis; in addition, to simulate trajectories during clinical gait analysis, we provide non-default paths for markers as inputs. Several calibration procedures are implemented and the same trial is processed with each calibration le, also considering dierent cameras congurations. The RMSEs between the measured trajectories and the optimal ones are calculated for each comparison. To investigate the signicant dierences between the computed indices, an ANOVA analysis is implemented. The RMSE is sensible to the variations of the considered calibration volume and the camera congurations and it is always inferior to 43 mm

    Sessile volatile drop evaporation under microgravity

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    The evaporation of sessile drops of various volatile and non-volatile liquids, and their internal flow patterns with or without instabilities have been the subject of many investigations. The current experiment is a preparatory one for a space experiment planned to be installed in the European Drawer Rack 2 (EDR-2) of the International Space Station (ISS), to investigate drop evaporation in weightlessness. In this work, we concentrate on preliminary experimental results for the evaporation of hydrofluoroether (HFE-7100) sessile drops in a sounding rocket that has been performed in the frame of the MASER-14 Sounding Rocket Campaign, providing the science team with the opportunity to test the module and perform the experiment in microgravity for six consecutive minutes. The focus is on the evaporation rate, experimentally observed thermo-capillary instabilities, and the de-pinning process. The experimental results provide evidence for the relationship between thermo-capillary instabilities and the measured critical height of the sessile drop interface. There is also evidence of the effects of microgravity and Earth conditions on the sessile drop evaporation rate, and the shape of the sessile drop interface and its influence on the de-pinning process

    Electron correlations in Mnx_xGa1x_{1-x}As as seen by resonant electron spectroscopy and dynamical mean field theory

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    After two decades from the discovery of ferromagnetism in Mn-doped GaAs, its origin is still debated, and many doubts are related to the electronic structure. Here we report an experimental and theoretical study of the valence electron spectrum of Mn-doped GaAs. The experimental data are obtained through the differences between off- and on-resonance photo-emission data. The theoretical spectrum is calculated by means of a combination of density-functional theory in the local density approximation and dynamical mean-field theory (LDA+DMFT), using exact diagonalisation as impurity solver. Theory is found to accurately reproduce measured data, and illustrates the importance of correlation effects. Our results demonstrate that the Mn states extend over a broad range of energy, including the top of the valence band, and that no impurity band splits off from the valence band edge, while the induced holes seem located primarily around the Mn impurity.Comment: 5 pages, 4 figure

    Concurrent repeatability and reproducibility analyses of four marker placement protocols for the foot-ankle complex

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    Multi-segment models of the foot have been proposed in the past years to overcome limitations imposed by oversimplified traditional approaches used to describe foot kinematics, but they have been only partially validated and never compared. This paper presents a unique comparative assessment of the four most widely adopted foot kinematic models and aims to provide a guidance for the clinical interpretation of their results. Sensitivity of the models to differences between treadmill and overground walking was tested in nine young healthy adults using a 1D paired t-test. Repeatability was assessed by investigating the joint kinematics obtained when the same operator placed the markers on thirteen young healthy adults in two occasions. Reproducibility was then assessed using data from three randomly selected participants, asking three operators to repeat the marker placement three times. The analyses were performed on sagittal kinematics using curve similarity and correlation indices (Linear Fit Method) and absolute differences between selected points. Differences between treadmill and overground gait were highlighted by all the investigated models. The two most repeatable and reproducible investigated models had average correlations higher than 0.70, with the lowest values (0.56) obtained for the midfoot. Averaged correlations were always higher than 0.74 for the former and 0.70 for the latter, with the lowest obtained for the midfoot (0.64 and 0.51). For all investigated models, foot kinematics generally showed low repeatability: normative bands must be adopted with caution when used for comparison with patient data

    Numerical study on Schramm-Loewner Evolution in nonminimal conformal field theories

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    The Schramm-Loewner evolution (SLE) is a powerful tool to describe fractal interfaces in 2D critical statistical systems. Yet the application of SLE is well established for statistical systems described by quantum field theories satisfying only conformal invariance, the so called minimal conformal field theories (CFTs). We consider interfaces in Z(N) spin models at their self-dual critical point for N=4 and N=5. These lattice models are described in the continuum limit by non-minimal CFTs where the role of a Z_N symmetry, in addition to the conformal one, should be taken into account. We provide numerical results on the fractal dimension of the interfaces which are SLE candidates for non-minimal CFTs. Our results are in excellent agreement with some recent theoretical predictions.Comment: 4 pages, 2 figures, v2: typos corrected, published versio

    Canine Mesenchymal Stem Cells from visceral and subcutaneuous adipose tissue for cell-based therapy

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    This study compared some characteristics of canine Adipose tissue-Derived Mesenchymal Stem Cells (cAD-MSCs) from subcutaneous and visceral fat. These findings were directed to obtain high quantity and quality cAD-MSCs for clinical cell-based therapy

    Choosing a similarity index to quantify gait data variability

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    Repeatability and reproducibility of joint kinematics can be assessed through Similarity Indices (SI) quantifying their pattern variability. These include: Coefficient of Multiple Correlation (CMC) [1]; Mean Absolute Variability (MAV) [2]; and Linear Fit Method (LFM) [3], which accounts for scaling (a1), offset (a0) and truthfulness of the linear model between the curves (R2). Among gait cycles, the intra-subject variability for a given joint is due to physiological fluctuations of the range of motion (ROM) and time shift. SIs might be differently affected for each joint, due to their different ROMs, and by marker positioning, leading to offsets among gait curves. This paper aims to investigate the effects that each of these sources of curve variability has on the SIs, in order to provide indications on which is the most suitable for the assessment of gait similarity

    Topical Treatment with Cord Blood Serum in Glaucoma Patients: A Preliminary Report

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    Purpose. To report data happened to be observed in two glaucoma patients treated with Cord Blood Serum (CBS) eyedrops. Design. Case report. Retrospective data analysis Methods. CBS topical eyedrops, characterized in advance for growth factors (GFs) content, were administered for two months with the aim to relieve their subjective symptoms, in two patients who had referred ocular surface discomfort, although in absence of any sign of keratopathy. As patients were also affected by advanced glaucoma at risk of vision loss, and under treatment with hypotensive drugs, they had been also monitored over the same period with IOP controls and Visual field tests in our Unit. Results. During subsequent visits, data from Mean Deviation and Pattern Standard Deviation in the Visual fields were retrospectively collected and compared before and after treatment with CBS, and an amelioration was observed. Conclusions. CBS contains a combination of GFs, which potentially exert a neuroprotective action and candidate CBS as an interesting natural source to be delivered in neurodegenerative ocular disorders. The incidentally observed amelioration in these two patients deserves further investigation in this respec
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