A Schr¨odinger-Poisson-Boltzmann system applied to the charge carrier transport in strained silicon

In this paper, a kinetic modeling of the electron transport inside a strained-silicon device structure is established. The reduced conduction band energy of a strained layer gives rise to a potential well structure, which may have a varying bottom energy. Electrons are introduced into the well by remote antimony doping, where they form a two-dimensional electron gas. Quantum-mechanical aspects are treated by using a self-consistent Schr¨odinger-Poisson block (subband model). To account for the transport properties of the strained-silicon device structure, an adapted semi-classical formulation of the Boltzmann transport equation is applied. This approach allows us to consistently include the relevant scattering mechanisms. The resulting coupled Schr¨odinger-Poisson-Boltzmann system is used for a phononlimited mobility estimate

Probability density functions for the variable solar wind near the solar cycle minimum

Unconditional and conditional statistics are used for studying the histograms of magnetic field multiscale fluctuations in the solar wind near the solar cycle minimum in 2008. The unconditional statistics involves the magnetic data during the whole year in 2008. The conditional statistics involves the magnetic field time series split into concatenated subsets of data according to a threshold in dynamic pressure. The threshold separates fast-stream leading edge compressional and trailing edge uncompressional fluctuations. The histograms obtained from these data sets are associated with both multiscale (B) and small-scale (δB) magnetic fluctuations, the latter corresponding to time-delayed differences. It is shown here that, by keeping flexibility but avoiding the unnecessary redundancy in modeling, the histograms can be effectively described by a limited set of theoretical probability distribution functions (PDFs), such as the normal, lognormal, kappa, and log-kappa functions. In a statistical sense the model PDFs correspond to additive and multiplicative processes exhibiting correlations. It is demonstrated here that the skewed small-scale histograms inherent in turbulent cascades are better described by the skewed log-kappa than by the symmetric kappa model. Nevertheless, the observed skewness is rather small, resulting in potential difficulties of estimation of the third-order moments. This paper also investigates the dependence of the statistical convergence of PDF model parameters, goodness of fit, and skewness on the data sample size. It is shown that the minimum lengths of data intervals required for the robust estimation of parameters is scale, process, and model dependent. ©2015. American Geophysical Union. All Rights Reserved

Razvoj i fizikokemijsko vrednovanje farmakosoma diklofenaka

Pharmacosomes are amphiphilic lipid vesicular systems that have shown their potential in improving the bioavailability of poorly water soluble as well as poorly lipophilic drugs. Diclofenac is a poorly water soluble drug and also causes gastrointestinal toxicity. To improve the water solublity of diclofenac, its pharmacosomes (phospholipid complex) have been prepared and evaluated for physicochemical analysis. Diclofenac was complexed with phosphatidylcholine (80 %) in equimolar ratio, in the presence of dichloromethane, by the conventional solvent evaporation technique. Pharmacosomes thus prepared were evaluated for drug solubility, drug content, surface morphology (by scanning electron microscopy), phase transition behaviour (by differential scanning calorimetry), crystallinity (by X-ray powder diffraction) and in vitro dissolution. Pharmacosomes of diclofenac were found to be irregular or disc shaped with rough surfaces in SEM. Drug content was found to be 96.2 1.1 %. DSC thermograms and XRPD data confirmed the formation of the phospholipid complex. Water solubility of the prepared complex was found to be 22.1 µg mL1 as compared to 10.5 µg mL1 of diclofenac. This improvement in water solubility in prepared pharmacosomes may result in improved dissolution and lower gastrointestinal toxicity. Pharmacosomes showed 87.8 % while the free diclofenac acid showed a total of only 60.4 % drug release at the end of 10 h of the dissolution study.Farmakosomi su amfifilni lipidni vezikularni sustavi sa sposobnošću poboljšanja bioraspoloživosti lijekova slabo topljivih u vodi i organskim otapalima. U svrhu povećanja topljivosti diklofenaka (ljekovite tvari koja je slabo vodotopljiva, a uzrokuje i gastrointestinalnu toksičnost) pripravljeni su i evaluirani njegovi farmakosomi (fosfolipidni kompleksi). Diklofenak je kompleksiran s fosfatidilkolinom (80 %) u ekvimolarnom omjeru, u prisutnosti diklormetana, konvencionalnom metodom evaporacije. Tako pripravljenim farmakosomima ispitivana je topljivost, sadržaj ljekovite tvari, morfologija površine (pomoću pretražne elektronske mikroskopije), ponašanje pri prijelazu faza (pomoću diferencijalne pretražne kalorimetrije), kristaliničnost (rendgenskom analizom praha) i in vitro oslobađanje. Farmakosomi diklofenaka su nepravilnog oblika ili u obliku diska te imaju neravnu površinu u SEM-u. Sadržaj ljekovite tvari je 96,2 1,1 %. DSC termogrami i XRPD podaci potvrdili su nastajanje fosfolipidnog kompleksa. Topljivost u vodi dobivenih kompleksa bila je 22,1 µg mL1, a topljivost samog diklofenaka 10,5 µg mL1. Postignuto poboljšanje topljivosti može imati za posljedicu povećano oslobađanje i manju gastrointestinalnu toksičnost. Tijekom 10 h iz farmakosoma se oslobodilo 87,8 %, a iz slobodnog diklofenaka samo 60,4 % ljekovite tvari

The unitary ability of IQ and indexes in WAIS-IV

Lichtenberger and Kaufman (2009, p. 167) defined unitary ability as ‘an ability […] that is represented by a cohesive set of scaled scores, each reflecting slightly different or unique aspects of the ability’. Flanagan and Kaufman (2009) and Lichtenberger and Kaufman (2012) used a difference of 23 IQ points between the highest score (Max) and the lowest score (Min) obtained by a subject in the four Indexes of the WAIS-IV to define unitarity of the total IQ score. A similar method has been used to assess the unitary ability of the four Indexes, with a threshold of 5 points. Such difference scores (of 23 for IQ and 5 for Indexes) are considered high and infrequent and the authors therefore conclude that the corresponding Full-Scale IQ score or Index score is uninterpretable. In this paper we argue that these thresholds are inappropriate because they are based on the wrong standard deviation. The main aim of this study was to establish variability thresholds for IQ and the WAIS-IV Indexes for the American standardization sample and to compare these thresholds with those for the Italian standardization sample. We also consider an alternative approach to determining whether an IQ score represents a unitary ability, based on the maximum difference score for the 10 core subtests that contribute to Full-Scale IQ scores

Monitoring Space Weather: Using Automated, Accurate Neural Network Based Whistler Segmentation for Whistler Inversion

It is challenging, yet important, to measure the - ever-changing - cold electron density in the plasmasphere. The cold electron density inside and outside of the plasmapause is a key parameter for radiation belt dynamics. One indirect measurement is through finding the velocity dispersion relation exhibited by lightning induced whistlers. The main difficulty of the method comes from low signal-to-noise ratios for most of the ground-based whistler components. To provide accurate electron density and L-shell measurements, whistler components need to be detectable in the noisy background, and their characteristics need to be reliably determined. For this reason precise segmentation is needed on a spectrogram image. Here we present a fully automated way to perform such an image segmentation by leveraging the power of convolutional neural networks, a state-of-the-art method for computer vision tasks. Testing the proposed method against a manually, and semi-manually segmented whistler dataset achieved <10% relative electron density prediction error for 80% of the segmented whistler traces, while for the L-shell, the relative error is <5% for 90% of the cases. By segmenting more than 1 million additional real whistler traces from Rothera station Antarctica, logged over 9 years, seasonal changes in the average electron density were found. The variations match previously published findings, and confirm the capabilities of the image segmentation technique

Photoelectric Emission from Interstellar Dust: Grain Charging and Gas Heating

We model the photoelectric emission from and charging of interstellar dust and obtain photoelectric gas heating efficiencies as a function of grain size and the relevant ambient conditions. Using realistic grain size distributions, we evaluate the net gas heating rate for various interstellar environments, and find less heating for dense regions characterized by R_V=5.5 than for diffuse regions with R_V=3.1. We provide fitting functions which reproduce our numerical results for photoelectric heating and recombination cooling for a wide range of interstellar conditions. In a separate paper we will examine the implications of these results for the thermal structure of the interstellar medium. Finally, we investigate the potential importance of photoelectric heating in H II regions, including the warm ionized medium. We find that photoelectric heating could be comparable to or exceed heating due to photoionization of H for high ratios of the radiation intensity to the gas density. We also find that photoelectric heating by dust can account for the observed variation of temperature with distance from the galactic midplane in the warm ionized medium.Comment: 50 pages, including 18 figures; corrected title and abstract field