Effect of mechanical compression on Cu(In,Ga)Se films : micro-structural and photoluminescence analysis

Cu(In,Ga)Se (CIGS) thin films were deposited by a two-step process on Mo-coated soda-lime glass substrates. The CuInGa (CIG) precursors were prepared in an in-line evaporation system at room temperature, and then selenised at 500 °C. The two-step processed CIGS films were mechanically compressed at 25 MPa to improve their optoelectronic properties, which were verified by photoluminescence (PL). The surface and structural properties were compared before and after compression. The mechanical compression has brought changes in the surface morphology and porosity without changing the structural properties of the material. The PL technique has been used to reveal changes in the electronic properties of the films. PL spectra at different excitation laser powers and temperatures were measured for as-grown as well as compressed samples. The PL spectra of the as-grown films revealed three broad and intense bands shifting at a significant rate towards higher energies (j-shift) with the increase in excitation power suggesting that the material is highly doped and compensated. At increasing temperature, the bands shift towards lower energies, which is a characteristic of the band tails generated by spatial potential fluctuation. The compression increases the intensity of energy bands by an order of magnitude and reduces the j-shift, demonstrating an improvement of the electronic properties

Statistics of a noise-driven Manakov soliton

We investigate the statistics of a vector Manakov soliton in the presence of additive Gaussian white noise. The adiabatic perturbation theory for Manakov soliton yields a stochastic Langevin system which we analyze via the corresponding Fokker-Planck equation for the probability density function (PDF) for the soliton parameters. We obtain marginal PDFs for the soliton frequency and amplitude as well as soliton amplitude and polarization angle. We also derive formulae for the variances of all soliton parameters and analyze their dependence on the initial values of polarization angle and phase.Comment: Submitted to J.Phys.A: Mathematical and Genera

The Plateau de Bure Neutron Monitor: design, operation and Monte-Carlo simulation

This paper describes the Plateau de Bure Neutron Monitor (PdBNM), an instrument providing continuous ground-level measurements of atmospheric secondary neutron flux resulting from the interaction of primary cosmic rays with the Earth's atmosphere. The detector is installed on the Plateau de Bure (Devoluy mountains, south of France, latitude North 44{\deg} 38' 02", longitude East 5{\deg} 54' 26", altitude 2555 m) as a part of the ASTEP Platform (Altitude Single-event effects Test European Platform), a permanent installation dedicated to the study of the impact of terrestrial natural radiation on microelectronics circuit reliability. The present paper reports the neutron monitor design, its operation since August 2008 and its complete numerical simulation using the Monte Carlo codes GEANT4 and MCNPX. We particularly detail the computation of the neutron monitor detection response function for neutrons, muons, protons and pions, the comparison between GEANT4 and MCNPX numerical results and the evaluation of the PdBNM counting rate a function of both the nature and flux of the incident atmospheric particles.Comment: 37 pages, 14 figures, 5 tables; numerical error in GEANT4 particle sourse corrected, section 4.4 was significantly revised. Submitted to IEEE Transactions on Nuclear Scienc

Gaussian Mixture Models and Model Selection for [18F] Fluorodeoxyglucose Positron Emission Tomography Classification in Alzheimer’s Disease

We present a method to discover discriminative brain metabolism patterns in [18F] fluorodeoxyglucose positron emission tomography (PET) scans, facilitating the clinical diagnosis of Alzheimer’s disease. In the work, the term “pattern” stands for a certain brain region that characterizes a target group of patients and can be used for a classification as well as interpretation purposes. Thus, it can be understood as a so-called “region of interest (ROI)”. In the literature, an ROI is often found by a given brain atlas that defines a number of brain regions, which corresponds to an anatomical approach. The present work introduces a semi-data-driven approach that is based on learning the characteristics of the given data, given some prior anatomical knowledge. A Gaussian Mixture Model (GMM) and model selection are combined to return a clustering of voxels that may serve for the definition of ROIs. Experiments on both an in-house dataset and data of the Alzheimer’s Disease Neuroimaging Initiative (ADNI) suggest that the proposed approach arrives at a better diagnosis than a merely anatomical approach or conventional statistical hypothesis testing

College of Arts and Sciences at Governors State University Announces Winter 2008 Dean’s List

The College of Arts and Sciences at Governors State University recently recognized undergraduate students who earned a 3.7 grade point average or higher during the Winter 2008 trimester

Application of virtual navigation in the treatment of macro-re-entrant atrial tachyarrhythmias

Macro-re-entrant atrial tachyarrhythmias occupy the leading positions in the structure of tachyarrhythmias, and one of the most common in this group is atrial flutter. These abnormal rhythms lead to a significant decrease in the quality of patients’ life, and sometimes, indirectly due to complications, can lead to disability and fatal consequences. Medical treatment for this group of arrhythmias has limited effectiveness, and the surgical method of treatment – catheter ablation – comes to the first place. Ablation of atrial flutter is traditionally performed under the guidance of fluoroscopy without the use of a navigation system, but this is associated with increased radiation exposure to patients and staff. Advances in modern arrhythmology make it possible to create anatomical models of heart chambers and activation models of the excitation spreading along anatomical models, reducing the radiation load, but requiring additional equipment and skills. Aim: to compare the procedure duration and radiation load during radiofrequency catheter ablation of the cavo-tricuspid isthmus using 3D navigation with traditional methods. Materials and methods. The work was based on the analysis of treatment results in 84 patients at National M. Amosov Institute of Cardiovascular Surgery affiliated to National Academy of Medical Sciences of Ukraine in the period from 2014 to 2021. Depending on the imaging method, patients were divided into 2 groups. Group I included 31 patients who underwent radiofrequency cavo-tricuspid isthmus (CTI) ablation according to the traditional method under fluoroscopic control without using a navigation system. Group II comprised 27 patients in whom an anatomical model of the right atrium was created. Results. Success criteria were achieved in all groups, bidirectional block line was created at the level of the CTI. In group I, the average time from the first application to the restoration of sinus rhythm was 325 ± 25 s with an average number of applications of 7.4 ± 0.6 (from 5 to 10). The average procedure time was 43.0 ± 3.3 min, with an average X-ray time of 572 ± 44 s and an average dose area product (DAP) was 62.0 ± 5.0 Gy.cm2. In group II, the total duration of the first stage of the intervention was 312 ± 26 s. The average time to stopping tachycardia and restoring sinus rhythm was 230 ± 19 s. The average time from sinus rhythm restoration to confirmation of bidirectional CTI block was 71 ± 6 s with an average number of applications of 3.2 ± 3.0 per the procedure. The average procedure time was 41.5 ± 3.5 min, the average X-ray time was 120 ± 10 s, the average DAP was 15.0 ± 1.3 Gy.cm2. Conclusions. The usage of the anatomical model of the right atrium reduces X-ray exposure by 75.8 %, in comparison to the traditional technique, during radiofrequency catheter ablation of the cavo-tricuspid isthmus with similar procedure time. The anatomical model can be recommended for ablation of the cavo-tricuspid isthmus

Interannual variability of the Black Sea Proper oxygen and nutrients regime: The role of climatic and anthropogenic forcing

The Black Sea is a unique, stratified, enclosed ocean basin of great importance. The water column provides a wealth of information concerning aerobic-anaerobic biogeochemistry, the responses of which can have links to anthropogenic and climatic forcing. Herein, we synthesize dissolved oxygen (DO) and nutrient data (phosphate, dissolved inorganic nitrogen (DIN), and silicate) for the period 1984-2010 received in the northeastern and western areas of the Sea. In the subsequent analysis we discuss the role of anthropogenic and climatic forcing in the context of the Black Sea oxic layer and oxic/anoxic interface characteristics.The DO concentration in the surface layer and in the Cold Intermediate Layer (CIL) decreased in warm periods and increased in cold periods, correlating to North Atlantic Oscillation (NAO) index variation. The biogeochemical regime of the Black Sea oxygenated upper layer has notably changed since 1999. After 1999 DO concentration in the CIL decreased by 20% while the concentrations in the surface layer changed very little. This provides evidence that the CIL waters were not fully replenished during the winters of the last decade.The nutrient concentrations (DIN and phosphate) in the surface layer decreased significantly in the 2000s compared with the 1980s-1990s. This decrease is regarded as improvement of the Black Sea ecosystem state. Oxygen and nutrient dynamics in the middle pycnocline have been decoupled since 1999. Presently physical (climatic) forcing is the dominant affecting factor controlling the Sea oxygen and nitrogen regime. © 2013 Elsevier Ltd

Optical properties of high quality Cu2ZnSnSe4 thin films

Cu2ZnSnSe4 thin films, fabricated on bare or molybdenum coated glass substrates by magnetron sputtering and selenisation, were studied by a range of techniques. Photoluminescence spectra reveal an excitonic peak and two phonon replicas of a donor-acceptor pair (DAP) recombination. Its acceptor and donor ionisation energies are 27 and 7 meV, respectively. This demonstrates that high-quality Cu2ZnSnSe4 thin films can be fabricated. An experimental value for the longitudinal optical phonon energy of 28 meV was estimated. The band gap energy of 1.01 eV at room temperature was determined using optical absorption spectr

The research program of the Liquid Scintillation Detector (LSD) in the Mont Blanc Laboratory

A massive (90 tons) liquid scintillation detector (LSD) has been running since October 1984 in the Mont Blanc Laboratory at a depth of 5,200 hg/sq cm of standard rock. The research program of the experiment covers a variety of topics in particle physics and astrophysics. The performance of the detector, the main fields of research are presented and the preliminary results are discussed