Ge-substitutional defects and the r3xr3 <--> 3x3 transition in alpha--SnGe(111)

The structure and energetics of Ge substitutional defects on the alpha-Sn/Ge(111) surface are analyzed using Density Functional Theory (DFT) molecular dynamics (MD) simulations. An isolated Ge defect induces a very local distortion of the 3x3 reconstruction, confined to a significant downwards displacement (-0.31 A) at the defect site and a modest upward displacement (0.05 A) of the three Sn nearest neighbours with partially occupied dangling bonds. Dynamical fluctuations between the two degenerate ground states yield the six-fold symmetry observed around a defect in the experiments at room temperature. Defect-defect interactions are controlled by the energetics of the deformation of the 3x3 structure: They are negligible for defects on the honeycomb lattice and quite large for a third defect on the hexagonal lattice, explaining the low temperature defect ordering.Comment: 4 pages, Revtex, 7 Encapsulated Postscript figures, uses epsf.sty. Submitted to Phys. Rev. Let

Calorons and BPS monopoles with non-trivial holonomy in the confinement phase of SU(2) gluodynamics

With the help of the cooling method applied to SU(2) lattice gauge theory at non-zero $T \le T_c$ we present numerical evidence for the existence of superpositions of Kraan-van Baal caloron (or BPS monopole pair) solutions with non-trivial holonomy, which might constitute an important contribution to the semi-classical approximation of the partition function.Comment: 3 pages, 6 figures, contribution to Lattice2002(topology

Dose, exposure time, and resolution in Serial X-ray Crystallography

The resolution of X-ray diffraction microscopy is limited by the maximum dose that can be delivered prior to sample damage. In the proposed Serial Crystallography method, the damage problem is addressed by distributing the total dose over many identical hydrated macromolecules running continuously in a single-file train across a continuous X-ray beam, and resolution is then limited only by the available molecular and X-ray fluxes and molecular alignment. Orientation of the diffracting molecules is achieved by laser alignment. We evaluate the incident X-ray fluence (energy/area) required to obtain a given resolution from (1) an analytical model, giving the count rate at the maximum scattering angle for a model protein, (2) explicit simulation of diffraction patterns for a GroEL-GroES protein complex, and (3) the frequency cut off of the transfer function following iterative solution of the phase problem, and reconstruction of an electron density map in the projection approximation. These calculations include counting shot noise and multiple starts of the phasing algorithm. The results indicate counting time and the number of proteins needed within the beam at any instant for a given resolution and X-ray flux. We confirm an inverse fourth power dependence of exposure time on resolution, with important implications for all coherent X-ray imaging. We find that multiple single-file protein beams will be needed for sub-nanometer resolution on current third generation synchrotrons, but not on fourth generation designs, where reconstruction of secondary protein structure at a resolution of 0.7 nm should be possible with short exposures.Comment: 19 pages, 7 figures, 1 tabl

Linkage disequilibrium fine mapping of quantitative trait loci: A simulation study

Recently, the use of linkage disequilibrium (LD) to locate genes which affect quantitative traits (QTL) has received an increasing interest, but the plausibility of fine mapping using linkage disequilibrium techniques for QTL has not been well studied. The main objectives of this work were to (1) measure the extent and pattern of LD between a putative QTL and nearby markers in finite populations and (2) investigate the usefulness of LD in fine mapping QTL in simulated populations using a dense map of multiallelic or biallelic marker loci. The test of association between a marker and QTL and the power of the test were calculated based on single-marker regression analysis. The results show the presence of substantial linkage disequilibrium with closely linked marker loci after 100 to 200 generations of random mating. Although the power to test the association with a frequent QTL of large effect was satisfactory, the power was low for the QTL with a small effect and/or low frequency. More powerful, multi-locus methods may be required to map low frequent QTL with small genetic effects, as well as combining both linkage and linkage disequilibrium information. The results also showed that multiallelic markers are more useful than biallelic markers to detect linkage disequilibrium and association at an equal distance

The Opinions of European Companies on Corporate Social Responsibility and Its Relation to Innovation

In recent years there has been greater concern among companies to include responsible practicesin their goals. To achieve this aim, companies are beginning to manage economic, socialand environmental factors following socially responsible practices. Adopting a strategy of CorporateSocial Responsibility (CSR) may influence the different policies implemented by thecompany, one of which is that regarding innovation. In this study, we analyze the opinions of95 European companies, 42 of which form part of the Dow Jones Sustainability Index (DJSI)and 53 of which belong to the Dow Jones General Index (DJGI), concerning their CSR policy,the innovation carried out and the relation between the two concepts. Our results show that theDJSI companies, unlike those belonging to the DJGI, consider their CSR strategy to be a keyfactor in generating competitive advantages and profits. Moreover, the companies surveyedhave implemented innovations that are more incremental than radical, and these innovationpractices are found to be influenced by CSR strategies

La asamblea como t?cnica para el desarrollo de la oralidad en los estudiantes del grado tercero de primaria de la institutci?n educativa Leonardo Posada Pedraza.

102 p. Recurso Electr?nicoLa investigaci?n cualitativa ?La asamblea como espacio did?ctico en el desarrollo de la oralidad?, est? inscrito en el proyecto Redescubrir la Escuela del programa de Lengua Castellana, tiene como prop?sito conocer las problem?ticas existentes al interior de las aulas de clase para implementar estrategias y t?cnicas de trabajo grupal que faciliten la reflexi?n-acci?n, para superar obst?culos interacci?nales en el entorno escolar y social. En este se describe y presenta el proceso aplicando el m?todo acci?n-participaci?n, mediante la observaci?n y recolecci?n de datos, realizado en la instituci?n educativa Colegio Leonardo Posada Pedraza grado tercero de primaria con 44 estudiantes entre 7 a 10 a?os de edad. Como es sabido los estudiantes al llegar a la escuela cuentan con una amplia experiencia de habla espont?nea e informal, pero estas no se evidencian en los usos formales m?s complejos, por esta raz?n, ellos requieren practicarlos de tal manera que se desenvuelvan pertinentemente en contextos reglados con el fin de mejor las capacidades verbales. El desarrollo adecuado de la oralidad, implica habla y silencio oportuno, establecer a qui?n dirigirse, c?mo hablar a personas con diferentes roles, cu?les son los comportamientos dentro de contextos y rutinas, mejorando as? las habilidades comunicativas. Para ello se mediatiza con la Asamblea, como t?cnica de discusi?n grupal, que pone al estudiante en situaci?n de habla formal. Demostrado que esta secuencia did?ctica puede desarrollase en cualquier nivel y situaci?n escolar, por su car?cter flexible, pues no pretende secuenciar la oralidad, sino establecer una gu?a de apoyo para que el estudiante potencie sus capacidades comunicativas.Qualitative research ?The assembly as educational didactic in the development of orality? he is enrolled in school rediscover project spanish language program, It aims to meet existing problems into classrooms to implement strategies and work techniques group to facilitate reflection and action, interactional overcoming obstacles in the school environment and social. This describes and presents the process applying the method action ? participation, through observation and data collection, at school Leonardo Posada Pedraza third grade forty- four students seven to eleven years old. As we know students to get to school have extensive experience spontaneous and informal talks, but these are not apparent in applications formal complex, for this reason, they require practicing such that unfold pertinently in situations regulated in order better verbal abilities. The proper development of orality, involves speaking and timely silence, establish where to turn, how to talk to people with different roles, which behaviors are within contexts and routines, improving communication skills. For it is mediated by the assembly, as a technique of group discussion, placing the student - formal speech. Demonstrated that this sequence didactic can develop at any level and school situation, its flexible nature, it is not intended sequence orality, but to establish a guide support for the student enhances their communication skills. Keywords: intervention, participatory action research, education, pedagogy, assembly, communicative competence, orality

Constraining the neutrino magnetic moment with anti-neutrinos from the Sun

We discuss the impact of different solar neutrino data on the spin-flavor-precession (SFP) mechanism of neutrino conversion. We find that, although detailed solar rates and spectra allow the SFP solution as a sub-leading effect, the recent KamLAND constraint on the solar antineutrino flux places stronger constraints to this mechanism. Moreover, we show that for the case of random magnetic fields inside the Sun, one obtains a more stringent constraint on the neutrino magnetic moment down to the level of \mu_\nu \lsim few \times 10^{-12}\mu_B, similar to bounds obtained from star cooling.Comment: 4 pages, 3 figures. Final version to appear in Phys. Rev. Let

Effect of antiseptic gels in the microbiologic colonization of the suture threads after oral surgery

Three different bioadhesive gels were evaluated in a double-blind randomized clinical trial in which microbial growth in the suture thread was assessed following post-surgical application of the aforementioned gels. Also assessed in this trial were, the intensity of post-surgical pain as well as the degree of healing of the patients' surgical wounds. A total of 21 patients (with 42 wisdom teeth) participated in this trial. Chlorhexidine gel, chlorhexidine-chitosan gel, and hyaluronic acid gel were evaluated, with a neutral water-based gel serving as the control agent. The aerobic and facultative anaerobic bacterial recovery on blood agar was lower in the placebo group than in the experimental groups. The most significant difference (p = 0.04) was observed in the chlorhexidine-chitosan group. in which the growth of Blood Agar and Mitis Salivarius Agar was significantly higher than in the placebo group. The intensity of post-surgical pain was very similar among all the groups. Significantly better healing rates were observed in the patients treated with chlorhexidine-chitosan gel when compared with those who used the placebo gel (p = 0.03), and in particular when compared with those patients who used hyaluronic acid gel (p = 0.01). Through our microbiological analyses, we were able to conclude that none of the bioadhesive gels tested resulted in beneficial reductions in the bacterial/fungal populations. However, the healing rates of patients who were treated with chlorhexidine-chitosan were better than those of the patients who used either the placebo gel or the hyaluronic acid gel