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A detailed theoretical and experimental study of the influence of injector doping on the output characteristics and electron heating in midinfrared GaAs/AlGaAs quantum cascade lasers is presented. The employed theoretical model of electron transport was based on a fully nonequilibrium self-consistent Schrödinger-Poisson analysis of the scattering rate and energy balance equations. Three different devices with injector sheet doping densities in the range of (4–6.5)×1011 cm–2 have been grown and experimentally characterized. Optimized arsenic fluxes were used for the growth, resulting in high-quality layers with smooth surfaces and low defect densities. A quasilinear increase of the threshold current with sheet injector doping has been observed both theoretically and experimentally. The experimental and calculated current-voltage characteristics are in a very good agreement. A decrease of the calculated coupling constant of average electron temperature versus the pumping current with doping level was found. [ABSTRACT FROM AUTHOR]

A design for a GaN/AlGaN optically pumped terahertz laser emitting at 34 μm (ΔE~36 meV) is presented. This laser uses a simple three-level scheme where the depopulation of the lower laser level is achieved via resonant longitudinal-optical-phonon emission. The quasibound energies and associated wave functions are calculated with the intrinsic electric field induced by the piezoelectric and the spontaneous polarizations. The structures based on a double quantum well were simulated and the output characteristics extracted using a fully self-consistent rate equation model with all relevant scattering processes included. Both electron-longitudinal-optical phonon and electron-acoustic-phonon interactions were taken into account. The carrier distribution in subbands was assumed to be Fermi-Dirac-like, with electron temperature equal to the lattice temperature, but with different Fermi levels for each subband. A population inversion of 12% for a pumping flux Φ=1027 cm-2 s-1 at room temperature was calculated for the optimized structure. By comparing the calculated modal gain and estimated waveguide and mirror losses the feasibility of laser action up to room temperature is predicted. [ABSTRACT FROM AUTHOR]

A criterion for strain balancing of wurtzite group-Ill nitride-based multilayer heterostructures is presented. Single and double strain-balanced GaN/AlGaN quantum well structures are considered with regard to their potential application in optoelectronic devices working at communication wavelengths. The results for realizable, strain-balanced structures are presented in the form of design diagrams that give both the intersubband transition energies and the dipole matrix elements in terms of the structural parameters. The optimal parameters for structures operating at λ∼1.3 and 1.55 µm were extracted and a basic proposal is given for a three level intersubband laser system emitting at 1.55 µm and depopulating via resonant longitudinal optical (LO) phonons (hω[sub LO]≈90 meV). [ABSTRACT FROM AUTHOR]

Hypogymnia physodes is known as dye source, as human food and as medicine. Since it is used as a food it is important to know are there any more beneficial effects on human organism and which compounds are responsible for these activities. Therefore, in this study the antimicrobial and antioxidant activities of H. physodes methanol extract (ME) and its constituents: depsidones, physodalic acid (I), physodic acid (II), 3-hydroxy physodic acid (III), and depside atranorin (IV) were investigated. To the best of our knowledge this would be the first information of antioxidant and antimicrobial activity of physodalic acid (I). All the tested components and extract showed antibacterial and antioxidant activities. Antifungal activity was not observed for the tested depsidones. The most sensitive, among bacteria was S. aureus and the highest resistance was shown by E. coli and P. aeruginosa. Only ME and atranorin were active toward C.albicans while A. niger was resistant on all tested samples. Among the analysed samples, compound III has the highest antioxidant capacity in all antioxidant experiments. Compound III showed higher antioxidant activity than commercial antioxidant BHT. The hydroxyl group in position 4 of dibenzo[b,e][1,4] dioxepine core can be of importance for its potent antioxidant activity. [ABSTRACT FROM AUTHOR]

Essential oils of many plants are widely used with a bias to have only positive effects on the body. Considering that terpenes are dominant ingredients of many essential oils, the influences of selected terpenes (geraniol, nerol, linalool, carvacrol) on the activities of the most important enzymes in clinical practice (creatine kinase, lactate dehydrogenase, amylase, alkaline phosphatase, gamma-glutamyltransferase, aspartate aminotransferase and alanine aminotransferase) are examined in this study. The survey was conducted in vitro with solutions of terpenes at concentrations in the range of 1.82-4.63 mmol/l and in commercial control human serum. Activities are measured by the standard clinical biochemical procedures. A decrease in activity of the enzyme to varying degrees was noted and it was ranged from 1/6 to slightly less than half of the enzyme activity, depending on the type of terpenes, the concentration of their solution, as well as the type of enzyme. The best inhibitor, in the described in vitro conditions, proved to be linalool (lavender), carvacrol (basil, oregano), geraniol (geranium) and the last nerol (orange). The results of this study confirm the initial hypothesis that the terpenes are, undoubtedly, those components of the essential oils that lead to significant inhibition of the clinical enzymes. [ABSTRACT FROM AUTHOR]

Period Batch Control (PBC) system has been known for its implementation with the classical group technology (GT) cells, and it has been known for its simplicity. The main production planning decisions concern the choice of the period length and the stage number and contents. Also, in order to better integrate the production planning with the application of GT cells at the shop floor, the concept of virtual manufacturing cells has been applied. Since virtual cells configurations are changing periodically, a model for implementing the PBC system into virtual manufacturing cells environment is developed. The model enables alignment of the PBC principles and rules with virtual cell design goals. Model is tested on the case study of furniture production. With the use of scheduling software, different scheduling rules were simulated for four production weeks. The experimental results from these for production weeks show how the choice of PBC parameters impacts the virtual cells configurations, machine sharing and utilization. [ABSTRACT FROM AUTHOR]

Chemical composition, total phenolic (TPC), total flavonoid (TFC) contents and antioxidant parameters: radical scavenging activity against DPPH and ABTS, total reducing power (TRP) and ferric reducing antioxidant power (FRAP), were determined in ten samples of propolis ethanol extract, originated from different regions of Serbia. The following constituents were detected in all samples: flavonoids (pinobanksin, chrysin, pinocembrin, galangin, pinostrobin and tectochrysin) and phenolic acids (caffeic acid and ferulic acid). All tested samples had better antioxidant properties in comparison with previously published results for propolis samples from different regions of the world. Obtained results indicate that the traditional Serbian procedure of preparing the extract of propolis is effective and the surrounding vegetation is a good source of the starting compounds for bees to produce propolis with good antioxidant properties. [ABSTRACT FROM AUTHOR]

Chemical composition, total phenolic (TPC), total flavonoid (TFC) contents and antioxidant parameters: radical scavenging activity against DPPH and ABTS, total reducing power (TRP) and ferric reducing antioxidant power (FRAP), were determined in ten samples of propolis ethanol extract, originated from different regions of Serbia. The following constituents were detected in all samples: flavonoids (pinobanksin, chrysin, pinocembrin, galangin, pinostrobin and tectochrysin) and phenolic acids (caffeic acid and ferulic acid). All tested samples had better antioxidant properties in comparison with previously published results for propolis samples from different regions of the world. Obtained results indicate that the traditional Serbian procedure of preparing the extract of propolis is effective and the surrounding vegetation is a good source of the starting compounds for bees to produce propolis with good antioxidant properties. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the content of elements in the parsley roots (Petroselinum crispum) of different geographic origin and estimate their possible sources applying chemometric analysis. The concentrations of 13 elements in parsley collected at 12 locations in five districts were examined. Cluster analysis (CA) separated elements into three statistical significant clusters: metalloids, heavy, and essential metals. Principal component analysis (PCA) permitted the reduction of 13 variables to three principal components explaining 82.3% of the total variance. The first component with 48.2% of variance comprises Al, Cu, Fe, Mn, Mo, Zn, and Co. Some of these metals are essential in low concentrations and their presence in plants is of lithogenic origin. Multivariate statistical analysis approach, such as PCA and CA can be used to assess the level of elements in vegetables. These methods can be used to identify sources of elements in plants too. [ABSTRACT FROM AUTHOR]

Background The present analysis aimed to estimate the penetration of cardiac resynchronization therapy (CRT) on the basis of the prevalence and incidence of eligible patients in selected European countries and in Israel. Methods and Results The following countries were considered: Italy, Slovakia, Greece, Israel, Slovenia, Serbia, the Czech Republic, Poland, Romania, Hungary, Ukraine, and the Russian Federation. CRT penetration was defined as the number of patients treated with CRT (CRT patients) divided by the prevalence of patients eligible for CRT. The number of CRT patients was estimated as the sum of CRT implantations in the last 5 years, the European Heart Rhythm Association (EHRA) White Book being used as the source. The prevalence of CRT indications was derived from the literature by applying three epidemiologic models, a synthesis of which indicates that 10% of heart failure (HF) patients are candidates for CRT. HF prevalence was considered to range from 1% to 2% of the general population, resulting in an estimated range of prevalence of CRT indication between 1000 and 2000 patients per million inhabitants. Similarly, the annual incidence of CRT indication, representing the potential target population once CRT has fully penetrated, was estimated as between 100 and 200 individuals per million. The results showed the best CRT penetration in Italy (47-93%), while in some countries it was less than 5% (Romania, Russian Federation, and Ukraine). Conclusion CRT penetration differs markedly among the countries analyzed. The main barriers are the lack of reimbursement for the procedure and insufficient awareness of guidelines by the referring physicians. [ABSTRACT FROM AUTHOR]

The Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) is an eight-band (355, 380, 445, 470, 555, 660, 865, 935 nm) pushbroom camera, measuring polarization in the 470, 660, and 865nm bands, mounted on a gimbal to acquire multiangular observations over a ±67° along-track range. The instrument has been flying aboard the NASA ER-2 high altitude aircraft since October 2010. AirMSPI employs a photoelastic modulator-based polarimetric imaging technique to enable accurate measurements of the degree and angle of linear polarization in addition to spectral intensity. A description of the AirMSPI instrument and ground data processing approach is presented. Example images of clear, hazy, and cloudy scenes over the Pacific Ocean and California land targets obtained during flights between 2010 and 2012 are shown, and quantitative interpretations of the data using vector radiative transfer theory and scene models are provided to highlight the instrument's capabilities for determining aerosol and cloud microphysical properties and cloud 3-D spatial distributions. Sensitivity to parameters such as aerosol particle size distribution, ocean surface wind speed and direction, cloud-top and cloud-base height, and cloud droplet size is discussed. AirMSPI represents a major step toward realization of the type of imaging polarimeter envisioned to fly on NASA's Aerosol-Cloud-Ecosystem (ACE) mission in the next decade. [ABSTRACT FROM AUTHOR]

The article presents a study which examines human papilloma virus (HPV) infection's correlation with colposcopy, cytology, and bioptic tissues' histopathological examination in intraepithelial lesions. The study collects data from year on 1,927 patients with age that ranges from 16-72 years, at the University Clinic of Gynecology and Obstetrics in Belgrade, Serbia. Results show that 272 women out of 1,927 were high-risk types (HR)-HPV positive and 635 showed an abnormal cytological findings.

Objective: The objective of the study was to asses the possible influence of hypothalamo–pituitary deficiencies, and growth hormone (GH) deficiency in particular, on cognition in adult patients with traumatic brain injury (TBI). TBI is a recently identified risk factor for cognitive deficits and hypopituitarism. Even the patients with favorable outcome after TBI may present with persistent bodily, psychosocial, and cognitive impairments, resembling patients with untreated partial or complete pituitary insufficiency. Design: We performed retrospective and cross-sectional study of endocrine and cognitive function in TBI in 61 patients (aged 37.7 ± 1.7 years) of both sexes (44 m,17 f), at least 1 year after TBI (3.9 ± 0.6 years). Serum insulin-like growth factor 1 (IGF-I), thyroxin, thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone (in men), prolactin, and cortisol were measured, and GH secretion was assessed by growth hormone releasing hormone (GHRH) + growth hormone releasing peptide-6 (GHRP-6) test. Cognitive function was assessed by using a standard neuropsychological battery. Results: GH deficiency (GHD) and GH insufficiency (GHI) were found in 20 patients (32.8%). After adjustment for confounders [age, body mass index (BMI), education level, time elapsed from TBI], there were no significant differences in results of neuropsychological tests between patients with TBI with GHD, GHI, and normal GH secretion. There were no correlations of neuropsychological variables with stimulated peak GH secretion or IGF-I level. Conclusions: GHD persists long after the TBI, independently of trauma severity and age at traumatic event. GH secretion is more sensitive to TBI than other pituitary hormones. No evidence is found for an association of cognitive function impairment and somatotropic axis impairment in adult patients tested more than 1 year after the TBI. [ABSTRACT FROM AUTHOR]

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The morphological evolution of both pits and SiGe islands on patterned Si(001) substrates is investigated. With increasing Si buffer layer thickness the patterned holes transform into multifaceted pits before evolving into inverted truncated pyramids. SiGe island formation and evolution are studied by systematically varying the Ge coverage and pit spacing and quantitative data on the influence of the pattern periodicity on the SiGe island volume are presented. The presence of pits allows the fabrication of uniform island arrays with any of their equilibrium shapes. [ABSTRACT FROM AUTHOR]

We report on a detailed experimental and theoretical analysis of the role of injector doping density on both the threshold current density (Jth) and the saturation current density (Jsat), determining the dynamic range of the quantum cascade lasers. The experimental results were obtained from two growth series of λ≈9 μm GaAs/Al0.45Ga0.55As quantum-cascade lasers based on single and double phonon resonance depopulation mechanisms. We derive a quasilinear dependence of Jth on the injector doping density of both designs for doping range as wide as (4–10)×1011 cm-2. Despite threshold current increase the faster rise of saturation current with doping results in an enhanced dynamic range for injector doping up to ∼8×1011 cm-2. For higher doping levels, Jsat itself saturates. Furthermore, our investigations yield that single phonon resonance devices exhibit clear current saturation simultaneously with a decrease of the optical power, whereas two phonon resonance devices show only power saturation, which we attribute to increased leakage currents. These deteriorate the laser performance of the latter design at higher operational temperatures. [ABSTRACT FROM AUTHOR]

The design and simulation of an In0.53Ga0.47As/Al0.56As0.44Sb quantum-cascade laser emitting in the near infrared is presented. Designed using a self-consistent rate equation solver coupled with an energy balance rate equation, the proposed laser has a calculated population inversion of ∼20% at 77 K and sufficient gain to achieve room-temperature laser emission at λ∼2.8 μm. Threshold currents in the range 4–8 kA/cm2 are estimated as the temperature increases from 77 K to 300 K. The output characteristics of the proposed laser are compared to an existing λ∼3.1 μm In0.53Ga0.47As/Al0.56As0.44Sb quantum-cascade structure presented in the literature. [ABSTRACT FROM AUTHOR]

The authors report a 58-year-old female who originally presented with acquired pure red cell aplasia (PRCA). At diagnosis, the karyotype was normal, the serum erythropoietin level was highly elevated and no T-cell mediated inhibition of erythropoiesis was demonstrated in coculture studies. Conventional immunossupressive therapy proved ineffective. A year later a diagnosis of hyperfibrotic myelodysplastic syndrome was assessed. The sequential bone marrow examinations in the course of the three years showed a progressive increase in bone marrow fibrosis, erythroid hyperplasia and dysmegakaryocytopoiesis, terminating in the acute myeloid leukemia. This sequence of the events included the appearance of del(5)(q13q33), four years after setting a diagnosis of PRCA. The authors suggest that the absence of both cytogenetic abnormality and the signs of dyshematopoiesis at the diagnosis of PRCA does not exclude ultimately a “clonal” category of the disease. Thus, repeated hematological and cytogenetical reevaluations are recommended. [ABSTRACT FROM AUTHOR]