Transition metal impurities on the bond-centered site in germanium.

We report on the lattice location of ion implanted Fe, Cu, and Ag impurities in germanium from a combined approach of emission channeling experiments and ab initio total energy calculations. Following common expectation, a fraction of these transition metals (TMs) was found on the substitutional Ge position. Less expected is the observation of a second fraction on the sixfold coordinated bond-centered site. Ab initio calculated heats of formation suggest this is the result of the trapping of a vacancy by a substitutional TM impurity, spontaneously forming an impurity-vacancy complex in the split-vacancy configuration. We also present an approach to displace the TM impurities from the electrically active substitutional site to the bond-centered site.

Phase-field modelling for metals and colloids and nucleation therein-an overview.

Phase-field modelling, as it is understood today, is still a young discipline in condensed matter physics, which established itself for that class of systems in condensed matter physics, which can be characterized by domains of different phases separated by a distinct interface. Driven out of equilibrium, their dynamics results in the evolution of those interfaces, during which those might develop into well-defined structures with characteristic length scales at the nano-, micro- or mesoscale. Since the material properties of such systems are, to a large extent, determined by those small-scale structures, acquiring a precise understanding of the mechanisms that drive the interfacial dynamics is a great challenge for scientists in this field. Phase-field modelling is an approach that allows us to tackle this challenge simulation-based. This overview summarizes briefly the essentials of the conceptual background of the phase-field method, as well as recent issues the phase-field community is focusing on, as far as they are related to nucleation. To that end a brief introduction to the basic understanding underlying the diffuse interface description, which is the conceptual backbone of phase-field modelling, is given at the beginning, followed by a detailed picture of its achievements so far in applications to nucleation phenomena in metals and colloids. Within the most relevant fields of condensed matter physics, approached by phase-field modelling until now, applications to metallic systems are a traditional domain of phase-field modelling and nucleation phenomena therein have been addressed by several groups. This paper provides an overview of these. Advances in the field of colloidal systems, on the other hand, are only more recent and are addressed here in the context of contributions to soft matter physics in general.

Morphology-dependent crossover effects in heterogeneous nucleation of peritectic materials studied via the phase-field method for Al-Ni.

The application of phase-field modeling to nucleation as a phenomenon at the nanoscale is justified, if one takes into account the great success of continuum approaches in nanofluidics as proven by the many comparisons to experiments. Employed in this manner it provides an approach allowing us to account for effects of the physical diffuseness of a nucleus' interface and thereby go beyond classical nucleation theory (Gránásy and James 2000 J. Chem. Phys. 113 9810; Emmerich and Siquieri 2006 J. Phys.: Condens. Matter 18 11121). Here we extend the focus of previous work in this field and address the question of how far the phase-field method can also be applied to gain further insight into nucleation statistics, in particular the nucleation prefactor appearing in the nucleation rate. In this context we describe in detail a morphology-dependent crossover effect noticeable for the nucleation rate at small driving forces.

Effect of noise-induced nucleation on grain size distribution studied via the phase-field crystal method.

We contribute to the more detailed understanding of the phase-field crystal model recently developed by Elder et al (2002 Phys. Rev. Lett. 88 245701), by focusing on its noise term and examining its impact on the nucleation rate in a homogeneously solidifying system as well as on successively developing grain size distributions. In this context we show that principally the grain size decreases with increasing noise amplitude, resulting in both a smaller average grain size and a decreased maximum grain size. Despite this general tendency, which we interpret based on Panfilis and Filiponi (2000 J. Appl. Phys. 88 562), we can identify two different regimes in which nucleation and successive initial growth are governed by quite different mechanisms.

An anisotropic phase-field crystal model for heterogeneous nucleation of ellipsoidal colloids.

We derive a generalized model for isotropic as well as anisotropic crystal lattice systems of arbitrary Poisson ratio within the framework of the continuum phase-field crystal (PFC) approach (Elder and Grant 2004 Phys. Rev. E 70 051606). To this end we extend the simplest PFC model defined by a free energy functional, which is based upon the Swift-Hohenberg model of pattern formation (Swift and Hohenberg 1993 Phys. Rev. A 15 851) to a conservative, anisotropic Langevin equation. By studying heterogeneous nucleation of ellipsoidal colloids at a wall, we demonstrate the capacity of our approach to contribute to the more precise understanding of condensed matter systems built up from non-spherical units at the atomic scale. In particular we address the question of how (a) the orientation of the ellipsoids as well as (b) the interaction potential with the wall determine the resulting contact angle.

Phase-field simulation of peritectic solidification closely coupled with directional solidification experiments in an Al-36 wt% Ni alloy.

In this work we present experimental and theoretical investigations of the directional solidification of Al-36 wt% Ni alloy. A phase-field approach (Folch and Plapp 2005 Phys. Rev. E 72 011602) is coupled with the CALPHAD (calculation of phase diagrams) method to be able to simulate directional solidification of Al-Ni alloy including the peritectic phase Al(3)Ni. The model approach is calibrated by systematic comparison to microstructures grown under controlled conditions in directional solidification experiments. To illustrate the efficiency of the model it is employed to investigate the effect of temperature gradient on the microstructure evolution of Al-36 wt% Ni during solidification.

Historia de la rinoplastía estética / History of esthetic rhinoplasty

La era de la rinoplastía estética comienza en 1887, cuando J.O. Roe, USA, publica su trabajo en que describe su técnica de reducción nasal usando únicamente incisiones endonasales. J. Joseph publica posteriormente su experiencia en rinoplastía. Este último, debido a sus grandes contribuciones al campo de la cirugía estética nasal y facial es considerado por la mayoría de los autores como el padre de la rinoplastía estética. En el transcurso del siglo pasado se han desarrollado y perfeccionado las técnicas de cirugía nasal destacando las contribuciones de numerosos cirujanos como: Safían, Autricht, Sercer, Padovan, Goodman, Anderson, Guerrerosantos, Killian, Cottle, etc

Dewetting hydrodynamics in 1+1 dimensions.

A model for the phase transition between partial wetting and dewetting of a substrate has been formulated that explicitly incorporates the hydrodynamic flow during the dewetting process in 1+1 dimensions. The model simulates a fluid layer of finite thickness on a substrate in coexistence with a dry part of the substrate and a gas phase above the substrate. Under nonequilibrium "dewetting" conditions, the front between the dry part and the wet part of the surface moves towards the wet part inducing hydrodynamic flow inside the wet layer. In more general terms, the model handles two immiscible fluids with a freely movable interface in an inhomogeneous external force field. Handling the interface by a new variant of the phase-field model, we obtain an efficient code with well-defined interfacial properties. In particular, the (free) energy can be chosen at will. We demonstrate that our model works well in the viscosity range of creeping flow and we give qualitative results for the higher Reynolds numbers. Connections to experimental realizations are discussed.

Rinosinusitis por pseudallescheria boydii: caso clínico / Rhinosinusitis caused by pseudallescheria boydii: a clinical case

Se presenta un caso clínico de rinosinusitis etmoidomaxilar micótica por Pseudallescheria boydii, con presentación de bola fúngica maxilar en una paciente inmunocompetente de 42 años de edad. El diagnóstico de infección por hongo fue efectuado por histopatología, y la identificación del agente, por estudio microbiológico. Fue tratada quirúrgicamente sin recibir tratamiento antifúngico sistémico. Evolucionó satisfactoriamente y con exámenes endoscópicos que mostraron un seno maxilar libre de enfermedad hasta el último control dos meses después del tratamiento quirúrgico. Se comentan aspectos clínicos, diagnósticos y terapéuticos de la pseudallescheriosis rinosinusal

Polimorfismo del gen de aldosa reductasa y velocidad de aparición de retinopatía en diabéticos no insulinodependientes / Aldose reductase gene polymorphism and rate of appearance of retinopathy in non insulin dependent diabetic patients

Background: Recent studies suggest that polymorphisms associated to the aldose reductase gene could be related to early retinopathy in noninsulin dependent diabetics (NIDDM). There is also new interest on the genetic modulation of coagulation factors in relation to this complication. Aim: To look for a possible relationship between the rate of appearance of retinopathy and the genotype of (AC)n polymorphic marker associated to aldose reductase gene. Patients and methods: A random sample of 27 NIDDM, aged 68.1 ñ 10.6 years, with a mean diabetes duration of 20.7 ñ 4.8 years and a mean glycosilated hemoglobin of 10.6 ñ 1.6 percent, was studied. The genotype of the (AC)n, polymorphic marker associated to the 5Õ end of the aldose reductase (ALR2) gene was determined by 32P-PCR plus sequenciation. Mutations of the factor XIII-A gene were studied by single stranded conformational polymorphism, sequenciation and restriction fragment length polymorphism. Results: Four patients lacked the (AC)24 and had a higher rate of appearance of retinopathy than patients with the (AC)24 allele (0.0167 and 0.0907 score points per year respectively, p=0.047). Both groups had similar glycosilated hemoglobin (11.7 ñ 0.2 and 10.5 ñ 1.6 percent respectively). Factor XIII gene mutations were not related to the rate of appearance of retinopathy. Conclusions: Our data suggest that the absence of the (AC)24 allele of the (AC)n polymorphic marker associated to the 5Õ end of the aldose reductase gene, is associated to a five fold reduction of retinopathy appearance rate

The uptake and release of ponasterone A by the Kc cell line of Drosophila melanogaster.

The association of ponasterone A (PNA) and 20-hydroxyecdysone with Kc cells is commensurate with their biological activity on this Kc cell line, the physiological activity ratio for PNA, 20-hydroxyecdysone and ecdysone is 1 : 50 : 2000, resp. Both association and release of [3H]-PNA are temperature-dependent, the activation energy was calculated as 16.7 cal (Arrhenius analysis). This association is compatible with unlabelled PNA and various ecdysteroids. The KD for PNA (Scatchard analysis) was estimated as 3.6 x 10(-9) M, giving the number of binding sites as approx. 1800 per cell.

Immunohistochemical localisation of ecdysteroids in the follicular epithelium of locust oocytes.

Frozen sections of growing terminal follicles of the locust ovary were incubated with an ecdysteroid-specific rabbit antibody and the bound antibody visualised by the use of FITC-labelled goat-anti-rabbit antiserum. A bright fluorescence was seen in the cytoplasm of the follicle cells in terminal follicles with a length between 4.0 and 6.0 mm with a maximum intensity at 5.5 mm, indicating the presence of ecdysteroids in these cells in this particular developmental stage.

A radioimmunoassay for arthropod moulting hormones, introducing a novel method of immunogen coupling.

Inokosteron-26-oic acid was coupled to thyroglobulin in aqueous pyridine by a water-soluble carbodiimide. After exhaustive dialysis and gel filtration on Sephadex G-25 in the presence of sodium dodecylsulfate, a coupling ratio of 164 haptens per molecule of thyroglobulin was determined. In all three animals injected with the conjugate, ecdysone-binding antibodies were detected. After one booster injection the antiserum could be diluted 1 : 5000 (1 : 4000, or 1 : 2000) in order to get a 50% binding of [3H]ecdysone. The dissociation constant was calculated as 5.8 X 10(-10) MOL/L. The antiserum has a greater affinity for ecdysone and 22-isoecdysone than for all other ecdysteroids and steroids tested.

The influence of parents and peers on choices made by adolescents.

Hypothetical situations in which an adolescent was faced with a choice of two possible alternatives, one favored by parents and the other favored by peers, were read by ninth- and twelfth-graders. Subjects were asked to pick the alternative most likely to be chosen by the adolescent in each situation. Responses were analyzed for tendency to choose parent- or peer-approved alternatives. Boys in the ninth grade chose the parent-approved alternative more often than either ninth-grade girls or twelfth-grade boys. Girls' responses tended to remain stable over the same period.

Derivatives of the insect moulting hormone for affinity chromatography, and their biological activities.

Several derivatives of the arthropod moulting hormone have been synthesized which were coupled to AH Sepharose 4B yielding about 2 mumole ligand per g wet gel. As an indication of the suitability of the ligands for biological work the puff inducing capacity of their methyl esters was tested. The methyl ester of inokosterone-C-26-carboxylic acid possesses the highest biological activity; lower activities were obtained with the esters of ecdysterone-C-6-CM-oxime and ecdysterone hemisuccinates. Therefore, inokosterone-C-26-carbocylic acid should be a useful ligand for affinity chromatography of ecdysone recptors from insect tissues.