Sharing Englishes & Social Media

This year-long grant-funded project examined the intersection of culture and class with use of the English Language, and explored the concept of multiple Englishes rather than one, monolithic, correct version of the language

Kondo resonances of transition-metal-atom impurities in a metal host: Dependence on d-orbital occupancy.

Kondo resonances for transition-metal-atom impurities in a metal host have been analyzed by means of an ionic model as a function of the impurity d-orbital occupancy. The ionic Hamiltonian has been obtained by making use of the atomic Hund first rule. This Hamiltonian has been solved using a Green-function equation of motion method up to second order in the transition metal–host interaction. We find Kondo temperatures that decrease with the atomic total spin, the largest one appearing for charge fluctuations d0d1 and d10d9, in good agreement with the experimental evidence.Fil: Goldberg, Edith Catalina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Flores, F.. Universidad Autónoma de Madrid; Españ

Rhapso : automatic stitching of mass segments from fourier transform ion cyclotron resonance mass spectra

Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) provides the resolution and mass accuracy needed to analyze complex mixtures such as crude oil. When mixtures contain many different components, a competitive effect within the ICR cell takes place that hampers the detection of a potentially large fraction of the components. Recently, a new data collection technique, which consists of acquiring several spectra of small mass ranges and assembling a complete spectrum afterward, enabled the observation of a record number of peaks with greater accuracy compared to broadband methods. There is a need for statistical methods to combine and preprocess segmented acquisition data. A particular challenge of quadrupole isolation is that near the window edges there is a drop in intensity, hampering the stitching of consecutive windows. We developed an algorithm called Rhapso to stitch peak lists corresponding to multiple different m/z regions from crude oil samples. Rhapso corrects potential edge effects to enable the use of smaller windows and reduce the required overlap between windows, corrects mass shifts between windows, and generates a single peak list for the full spectrum. Relative to a stitching performed manually, Rhapso increased the data processing speed and avoided potential human errors, simplifying the subsequent chemical analysis of the sample. Relative to a broadband spectrum, the stitched output showed an over 2-fold increase in assigned peaks and reduced mass error by a factor of 2. Rhapso is expected to enable routine use of this spectral stitching method for ultracomplex samples, giving a more detailed characterization of existing samples and enabling the characterization of samples that were previously too complex to analyze

Bayesian survival modelling of university outcomes

Dropouts and delayed graduations are critical issues in higher education systems world wide. A key task in this context is to identify risk factors associated with these events, providing potential targets for mitigating policies. For this, we employ a discrete time competing risks survival model, dealing simultaneously with university outcomes and its associated temporal component. We define survival times as the duration of the student's enrolment at university and possible outcomes as graduation or two types of dropout (voluntary and involuntary), exploring the information recorded at admission time (e.g. educational level of the parents) as potential predictors. Although similar strategies have been previously implemented, we extend the previous methods by handling covariate selection within a Bayesian variable selection framework, where model uncertainty is formally addressed through Bayesian model averaging. Our methodology is general; however, here we focus on undergraduate students enrolled in three selected degree programmes of the Pontificia Universidad Católica de Chile during the period 2000–2011. Our analysis reveals interesting insights, highlighting the main covariates that influence students’ risk of dropout and delayed graduation

Incorporating unobserved heterogeneity in Weibull survival models : a Bayesian approach

Outlying observations and other forms of unobserved heterogeneity can distort inference for survival datasets. The family of Rate Mixtures of Weibull distributions includes subject-level frailty terms as a solution to this issue. With a parametric mixing distribution assigned to the frailties, this family generates flexible hazard functions. Covariates are introduced via an Accelerated Failure Time specification for which the interpretation of the regression coefficients does not depend on the choice of mixing distribution. A weakly informative prior is proposed by combining the structure of the Jeffreys prior with a proper prior on some model parameters. This improper prior is shown to lead to a proper posterior distribution under easily satisfied conditions. By eliciting the proper component of the prior through the coefficient of variation of the survival times, prior information is matched for different mixing distributions. Posterior inference on subject-level frailty terms is exploited as a tool for outlier detection. Finally, the proposed methodology is illustrated using two real datasets, one concerning bone marrow transplants and another on cerebral palsy

Modern concepts in non-surgical esthetics; a review

New non-surgical esthetics is the most dynamic field in contemporary medicine. At the same time, it is greatly influenced by our contemporary society. This paper reviews modern methods used in non-surgical esthetics, especially in Romania. From injectology and non-surgical face lifting to non-surgical body contouring, we analyzed all procedures performed by Romanian physicians, and we show the advantages and disadvantages of the advanced esthetic procedures. Injectology typically implies hyaluronic acid, botox and mesotherapy (for wrinkles and rejuvenation). Laser and radiofrequency treatment are used for wrinkles as well, with fewer unwanted adverse reactions and results exceeding those of injectables. Non-surgical lifting has gained more ground because it requires little recovery time and the results are very positive. Elective treatment for facial discoloration is the laser approach. For non-surgical body contouring, cryolipolisis, vacuum, radio frequency, and infrared systems have all revolutionized this part of esthetics, but each has limitations, and only after establishing the correct course of action, might we think of achieving favorable results and thus raising to the expectations of patients

Fluorescent Probes for Monitoring the UV Curing of Acrylic Adhesives, 1. FTIR and Fluorescence in Real Time

The use of the fluorescence technique for monitoring the UV-curing of two polyurethane-based adhesives containing acrylic monomers is described in this paper. The increase of the fluorescence intensity as well as the maximum wavelength shift on emission was measured in real time during the photopolymerisation process. The established relationship between fluorescence and conversion allowed monitoring of the course of the process beyond vitrification. In that sense, all the fluorescent probes studied were sensitive to the formulation curing and in some cases, the range of conversions in which they were useful was limited by their size and probably, by the free volume fraction in the polymeric matrix. Moreover, polymerisation rates were obtained from fluorescent kinetic profiles and used to carry out a comparative study of the different photosensitive formulations. The real time FTIR (RTIR) results show the highest photoinitiation efficiency of the photoinitiator 2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone (Irgacure 369) compared to that of 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651). The limitation of RTIR method for monitoring slow post-reactions was overcome by the use of the fluorescence-based method. Thus, a fluorescence intensity increase and a blue-shift of the emission band were measured after the limiting conversion was attained. Dynamic mechanical analysis showed that the glass transition temperature of the polymer increases during prolonged exposure to irradiation confirming the increase of the system rigidity.The authors would like to thank the Union European Commission for funding through the BRITE-Euram Project (BE97-4472). Gratitude is also extended to Comisión Interministerial de Ciencia y Tecnología (CICYT) for financial support (MAT97-0727) and to Comunidad Autónoma de Madrid, CAM (07N/0002/1998), as well as to the Spanish Ministerio de Educación y Cultura. We thank Dr. K. Dietliker, from Ciba Speciality Chemicals, for providing the photoinitiators and also the Loctite Corporation for the adhesives