A search for periodicities from a ULX in the LINER galaxy NGC 4736

We report our findings on a new quasi-periodic oscillation (QPO) and a long period from the ultraluminous X-ray source (ULX) X-2 in nearby galaxy NGC 4736 based on the Chandra and XMM-Newton archival data. To examine the timing properties, power density spectra of the source have been obtained using Fast Fourier Transform. Also the spectral parameters of the source have been calculated by obtaining and fitting the energy spectra. Power density spectrum of this source reveals a QPO peak at $0.73_{-0.14}^{+0.16}$ mHz with an fractional rms variability of 16% using the Chandra data (in the year 2000-lower state of the source). The XMM-Newton data analysis indicates a peak at $0.53_{-0.35}^{+0.09}$ mHz with a fractional rms variation of 5% (in the year 2006-higher state of the source). These recovered QPOs overlap within errors and may be the same oscillation. In addition, we detect a long periodicity or a QPO in the Chandra data of about $(5.2\pm2.0)\times10^{-5}$ Hz ($\sim$ 5.4 hrs) over 3 $\sigma$ confidence level. If this is a QPO, it is the lowest QPO detected from a ULX. The mass of the compact object in ULX X-2 is estimated using the Eddington luminosity and a disk blackbody model in the range (10$-$80) M_{\sun}.Comment: 6 pages, 4 Figures; Accepted for publication in Astrophysics and Space Scienc

Finite Element Analysis of Strain Effects on Electronic and Transport Properties in Quantum Dots and Wires

Lattice mismatch in layered semiconductor structures with submicron length scales leads to extremely high nonuniform strains. This paper presents a finite element technique for incorporating the effects of the nonuniform strain into an analysis of the electronic properties of SiGe quantum structures. Strain fields are calculated using a standard structural mechanics finite element package and the effects are included as a nonuniform potential directly in the time independent Schrodinger equation; a k-p Hamiltonian is used to model the effects of multiple valence subband coupling. A variational statement of the equation is formulated and solved using the finite element method. This technique is applied to resonant tunneling diode quantum dots and wires; the resulting densities of states confined to the quantum well layers of the devices are compared to experimental current-voltage I(V) curves.Comment: 17 pages (LaTex), 18 figures (JPEG), submitted to Journal of Applied Physic

Preservice teachers' perceptions about their problem solving skills in the scenario based blended learning environment

The purpose of this study is to determine how to react everyday lives problems in general. In the study, a pretest-posttest quasi-experimental design was used. The study group consisted of 37 students who were registered for Teacher Experience Course of Computer & Instructional Technologies Education in their 8th semester. In order to collect data The Problem Solving Inventory, a 6 point likert scale with 35 items was used. The scale was completed by the participants both at the beginning and at the end of the 8th semester. In the study as an online learning environment, MODDLE which is a learning management system was used. At the beginning of the semester students who would go to the public primary institutions once a week were randomly assigned to one of the five schools. In the study, participants were given scenarios once a week, totally 8 scenarios and wanted to generate solutions for these problems. Scenarios and solutions were discussed at the face to face courses, semiweekly and gave feedback to them about their solutions by the researchers. At last week, the period of Teaching Practice and generated solutions according to presented problems were assessed, and participants were wanted to respond the scale again. Descriptive statistics and t-test statistical technique were used to analysis of data. The result of the study indicated that there is a significant difference in favour of average points of posttest

LONG RANGE LAKE WATER LEVEL ESTIMATION USING ARTIFICIAL INTELLIGENCE METHODS

Ovaj rad obuhvaća predviđanje vodostaja jezera Beysehir, smještenog u središtu Turske, pomoću umjetne inteligencije (AI) poput neuronskih mreža (NN) i neizrazite logike (FL). Studija razmatra detaljno istraživanje utjecaja trajanja dugoročnog predviđanja na predviđanje vodostaja jezera. Analizirana razdoblja predviđanja su bila 1 dan, 30 dana, 60 dana i 90 dana. Parametri jezera poput kratkovalnog zračenja, ukupne brzine dotjecanja u jezero, ukupne brzine otjecanja iz jezera i ranijih vodostaja jezera činili su ulazni sloj AI konfiguracija. Ova studija je jasno pokazala da se uspješnost predviđanja AI metodama smanjuje s povećanjem razdoblja predviđanja. Također se vidi da se najbolji kriteriji za uspješnost predviđanja dobivaju različitim AI metodama za različita razdoblja predviđanja. Vidljivo je da je generalizirana regresijska neuronska mreža (GRNN) pokazala relativno bolje rezultate u usporedbi s druge dvije umjetne neuronske mreže, tj. radijalnom baznom funkcijom (RBF) i metodom proslijeđivanja prema naprijed s povratnim rasprostiranjem pogreške (FFBP), te metodom prilagodljivog sustava neuro-neizrazitog zaključivanja (ANFIS), za duga razdoblja predviđanja, kao što su 60 i 90 dana. Drugu ukupnu najbolju uspješnost postigla je FFBP.This paper covers the estimation of the water levels of Beysehir Lake, located in middle of Turkey, using the artificial intelligence (AI) such as the neural networks (NN) and the fuzzy logic (FL). The study considers the detailed investigation of the effect of the long-term estimate duration on the lake water level estimation. The analysed estimate ranges were 1 day, 30 days, 60 days and 90 days. The lake parameters such as the shortwave radiation, the lake total inflow rate, the lake total outflow rate and the past lake water levels constituted the input layer of the AI configurations. This study clearly showed that the estimate performance of the AI methods decreases with the increasing estimate range. It is also seen that the best estimate performance criteria are obtained by different AI methods for different estimate ranges. It is seen that the Generalized Regression Neural Network (GRNN) showed relatively superior performance compared with the other two artificial neural networks, i.e. the Radial Basis Function (RBF) and the Feed Forward Back Propagation method (FFBP), and the Adaptive Neuro-Fuzzy Inference System (ANFIS) method, for the long estimation ranges such as 60 and 90 days. The second overall best performance was obtained by FFBP

Controlled growth and characterization of epitaxially-laterally-overgrown InGaN/GaN quantum heterostructures

Crystal material quality is fundamentally important for optoelectronic devices including laser diodes and light emitting diodes. To this end epitaxial lateral overgrowth (ELO) has proven to be a powerful technique for reducing dislocation density in GaN and its alloys [1,2]. Implementation and design of ELO process is, however, critical for obtaining high-quality material with high-efficiency quantum structures for light emitters [3]. ©2010 IEEE

White emitting CdS quantum dot nanoluminophores hybridized on near-ultraviolet LEDs for high-quality white light generation and tuning

To generate white light using semiconductor nanocrystal (NC) quantum dots integrated on light emitting diodes (LEDs), multiple hybrid device parameters (emission wavelengths of the NCs and the excitation platform, order of the NCs with different sizes, amount of the different types of NCs, etc) need to be carefully designed and properly implemented. In this study, we introduce and demonstrate white LEDs based on simple device hybridization using only a single type of white emitting CdS quantum dot nanoluminophores on near-ultraviolet LEDs. Here we present their design, synthesis-growth, fabrication and characterization. With these hybrid devices, we achieve high color rendering index (>70), despite using only a single NC type. Furthermore, we conveniently tune their photometric properties including the chromaticity coordinates, correlated color temperature, and color rendering index with the number of hybridized nanoluminophores in a controlled manner. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft

Multi-material specific, targeted self-assembly of nanocrystal emitters using genetically engineered peptides on optoelectronic microchips

[No abstract available

White CdS nanoluminophore based tunable hybrid light emitting diodes

[No abstract available

Functional bowel disorders with diarrhoea: Clinical guidelines of the United European Gastroenterology and European Society for Neurogastroenterology and Motility

Irritable bowel syndrome with diarrhoea (IBS-D) and functional diarrhoea (FDr) are the two major functional bowel disorders characterized by diarrhoea. In spite of their high prevalence, IBS-D and FDr are associated with major uncertainties, especially regarding their optimal diagnostic work-up and management. A Delphi consensus was performed with experts from 10 European countries who conducted a literature summary and voting process on 31 statements. Quality of evidence was evaluated using the grading of recommendations, assessment, development, and evaluation criteria. Consensus (defined as >80% agreement) was reached for all the statements. The panel agreed with the potential overlapping of IBS-D and FDr. In terms of diagnosis, the consensus supports a symptom-based approach also with the exclusion of alarm symptoms, recommending the evaluation of full blood count, C-reactive protein, serology for coeliac disease, and faecal calprotectin, and consideration of diagnosing bile acid diarrhoea. Colonoscopy with random biopsies in both the right and left colon is recommended in patients older than 50 years and in presence of alarm features. Regarding treatment, a strong consensus was achieved for the use of a diet low fermentable oligo-, di-, monosaccharides and polyols, gut-directed psychological therapies, rifaximin, loperamide, and eluxadoline. A weak or conditional recommendation was achieved for antispasmodics, probiotics, tryciclic antidepressants, bile acid sequestrants, 5-hydroxytryptamine-3 antagonists (i.e. alosetron, ondansetron, or ramosetron). A multinational group of European experts summarized the current state of consensus on the definition, diagnosis, and management of IBS-D and FDr