Tools in Spanish Universities to facilitate the transmission from High School to University and their assessment.

Incoming students in the University have education deficiencies, so universities studies require a sound basis of scientific knowledge. In this project are analysed instruments to reinforcing knowledge in those areas related to the studies that students are about to embark on public Spanish universities. There are important differences among universities and, in each university there are great differences among titles. Initial courses (cursos cero) are widespread (in 50% of universities) that selfevaluation instruments (14 % of universities). It is necessary to improve diffusion of those instruments because it is not possible to evaluate them. So are proposed the next actuations: to make regular standard surveys for professors and students; to publish results of surveys; public universities should institutionalize their basic training offer and improve the dissemination of this offer especially through the web. This paper presents a questionnaire to assess student opinion about these tools. To analyze the effectiveness, and make an initial estimate of the evaluation of these tools, we conducted a pilot test of the questionnaire with 68 students at the University of Extremadura. The results of preliminary statistical analysis conducted on the pilot test indicate that the survey results are reliable. A global evaluation of both tools, with a scale of 1 to 5, gave an average score of 3.29 for initial courses and 3.41 for selfevaluation. The 72.9% of the students consider the "self assessment" more effective than the "initial course

Assessment of the Sampling Performance of Multiple-Copy Dynamics versus a Unique Trajectory

The goal of the present study was to ascertain the differential performance of a long molecular dynamics trajectory versus several shorter ones starting from different points in the phase space and covering the same sampling time. For this purpose, we selected the 16-mer peptide Bak(16)BH3 as a model for study and carried out several samplings in explicit solvent. These samplings included an 8 mu s trajectory (sampling Si); two 4 us trajectories (sampling S2); four 2 mu s trajectories (sampling S3); eight 1 mu s trajectories (sampling S4); 16 0.5 mu s trajectories (sampling S5), and 80 0.1 mu s trajectories (sampling S6). Moreover, the 8 mu s trajectory was further extended to 16 pis to have reference values of the diverse properties measured. The diverse samplings were compared qualitatively and quantitatively. Among the former, we carried out a comparison of the conformational profiles of the peptide using cluster analysis. Moreover, we also gained insight into the interchange among these structures along the sampling process. Among the latter, we computed the number of new conformational patterns sampled with time using strings defined from the conformations attained by each of the residues in the peptide. We also compared the locations and depths of the obtained minima on the free energy surface using principal component analysis. Finally, we also compared the helical profiles per residue at the end of the sampling process. The results suggest that a few short molecular dynamics trajectories may provide better sampling than one unique trajectory. Moreover, this procedure can also be advantageous to avoid getting trapped in a local minimum. However, caution should be exercised since short trajectories need to be long enough to overcome local barriers surrounding the starting point and the required sampling time depends on the number of degrees of freedom of the system under study. An effective way to gain insight into the minimum MD trajectory length is to monitor the convergence of different structural features, as shown in the present Wor

Stress compensation by gap monolayers for stacked InAs/GaAs quantum dots solar cells

In this work we report the stacking of 10 and 50 InAs quantum dots layers using 2 monolayers of GaP for stress compensation and a stack period of 18 nm on GaAs (001) substrates. Very good structural and optical quality is found in both samples. Vertical alignment of the dots is observed by transmission electron microscopy suggesting the existence of residual stress around them. Photocurrent measurements show light absorption up to 1.2 μm in the nanostructures together with a reduction in the blue response of the device. As a result of the phosphorus incorporation in the barriers, a very high thermal activation energy (431 meV) has also been obtained for the quantum dot emission

Community-acquired pneumonia: development of a bedside predictive model and scoring system to identify the aetiology

AbstractAlthough initial presentation has been commonly used to select empirical therapy in patients with community-acquired pneumonia (CAP), few studies have provided a quantitative estimation of its value. The objective of this study was to analyse whether a combination of basic clinical and laboratory information performed at bedside can accurately predict the aetiology of pneumonia.A prospective study was developed among patients admitted to the Emergency Department University Hospital Arnau de Vilanova, Lleida, Spain, with CAP. Informed consent was obtained from patients in the study. At entry, basic clinical (age, comorbidity, symptoms and physical findings) and laboratory (white blood cell count) information commonly used by clinicians in the management of respiratory infections, was recorded. According to microbiological results, patients were assigned to the following categories: bacterial (Streptococcus pneumoniae and other pyogenic bacteria), virus-like (Mycoplasma pneumoniae, Chlamydia spp and virus) and unknown pneumonia. A scoring system to identify the aetiology was derived from the odds ratio (OR) assigned to independent variables, adjusted by a logistic regression model. The accuracy of the prediction rule was tested by using receiver operating characteristic curves.One hundred and three consecutive patients were classified as having virus-like (48), bacterial (37) and unknown (18) pneumonia, respectively. Independent predictors related to bacterial pneumonia were an acute onset of symptoms (OR 31; 95% Cl, 6–150), age greater than 65 or comorbidity (OR 6·9; 95% Cl, 2–23), and leukocytosis or leukopenia (OR 2; 95% Cl, 0·6–7). The sensitivity and specificity of the scoring system to identify patients with bacterial pneumonia were 89% and 94%, respectively. The prediction rule developed from these three variables classified the aetiology of pneumonia with a ROC curve area of 0·84.Proper use of basic clinical and laboratory information is useful to identify the aetiology of CAP. The prediction rule may help clinicians to choose initial antibiotic therapy

Spectropolarimetric multi line analysis of stellar magnetic fields

In this paper we study the feasibility of inferring the magnetic field from polarized multi-line spectra using two methods: The pseudo line approach and The PCA-ZDI approach. We use multi-line techniques, meaning that all the lines of a stellar spectrum contribute to obtain a polarization signature. The use of multiple lines dramatically increases the signal to noise ratio of these polarizations signatures. Using one technique, the pseudo-line approach, we construct the pseudo-line as the mean profile of all the individual lines. The other technique, the PCA-ZDI approach proposed recently by Semel et al. (2006) for the detection of polarized signals, combines Principle Components Analysis (PCA) and the Zeeman Do ppler Imaging technique (ZDI). This new method has a main advantage: the polarized signature is extracted using cross correlations between the stellar spectra nd functions containing the polarization properties of each line. These functions are the principal components of a database of synthetic spectra. The synthesis of the spectra of the database are obtained using the radiative transfer equations in LTE. The profiles built with the PCA-ZDI technique are denominated Multi-Zeeman-Signatures. The construction of the pseudo line as well as the Multi-Zeeman-Signatures is a powerful tool in the study of stellar and solar magnetic fields. The information of the physical parameters that governs the line formation is contained in the final polarized profiles. In particular, using inversion codes, we have shown that the magnetic field vector can be properly inferred with both approaches despite the magnetic field regime.Comment: Accepted for publication in Astronomy and Astrophysic

Insights into the room temperature magnetism of ZnO/Co3O4 mixtures

The origin of room temperature (RT) ferromagneticlike behavior in ZnO-based diluted magnetic semiconductors is still an unclear topic. The present work concentrates on the appearance of RT magnetic moments in just mixed ZnO/Co3O4 mixtures without thermal treatment. In this study, it is shown that the magnetism seems to be related to surface reduction of the Co3O4 nanoparticles, in which, an antiferromagnetic Co3O4 nanoparticle (core) is surrounded by a CoO-like shell. This singular superficial magnetism has also been found in other mixtures with semiconductors such as TiO2 and insulators such as Al2O3