Relaxation Properties of Small-World Networks

Recently, Watts and Strogatz introduced the so-called small-world networks in order to describe systems which combine simultaneously properties of regular and of random lattices. In this work we study diffusion processes defined on such structures by considering explicitly the probability for a random walker to be present at the origin. The results are intermediate between the corresponding ones for fractals and for Cayley trees.Comment: 16 pages, 6 figure

Luminescent Bimetallic IrIII /AuI Peptide Bioconjugates as Potential Theranostic Agents

Diverse iridium peptide bioconjugates and the corresponding iridium/gold bimetallic complexes have been synthesized starting from a cyclometallated carboxylic acid substituted IrIII complex [Ir(ppy)2 (Phen-5-COO)] by solid phase peptide synthesis (SPPS). The selected peptide sequences were an enkephalin derivative Tyr-Gly-Gly-Phe-Leu together with the propargyl-substituted species Tyr-Gly-Pgl-Phe-Leu to allow gold coordination (Pgl: propyrgyl-glycine, HC=C-Gly), and a specific short peptide, Ala-Cys-Ala-Phen, containing a cysteine residue. Introduction of the gold center has been achieved via a click reaction with the alkynyl group leading to an organometallic Au-C(triazole) species, or by direct coordination to the sulfur atom of the cysteine. The photophysical properties of these species revealed predominantly an emission originating from the Ir complex, using mixed metal-to-ligand and ligand-to-ligand charge transfer excited states of triplet multiplicity. The formation of the peptide bioconjugates caused a systematic redshift of the emission profiles. Lysosomal accumulation was observed for all the complexes, in contrast to the expected mitochondrial accumulation triggered by the gold complexes. Only the cysteine-containing Ir/Au bioconjugate displayed cytotoxic activity. The absence of activity may be related to the lack of endosomal/lysosomal escape for the cationic peptide conjugates. Interestingly, the different coordination sphere of the gold atom may play a crucial role, as the Au-S(cysteine) bond may be more readily cleaved in a biological environment than the Au-C(triazole) bond, and thus the Au fragment could be released from or trapped in the lysosomes, respectively. This work represents a starting point in the development of bimetallic peptide bioconjugates as theranostics and in the knowledge of factors that contribute to anti-proliferative activity

Block copolymer based novel magnetic mixed matrix membranes-magnetic modulation of water permeation by irreversible structural changes

This contribution focuses on understanding the effect of magnetic field intensity on the performance of novel hydrophilic and hydrophobic mixed matrix membranes (MMMs). The hydrophilic MMMs were made up of polymeric nanoparticles (PNPs) that were synthesized through polymerization-induced self-assembly (PISA) and iron oxide nanoparticles prepared in presence of poly (methacrylic acid)-b-poly quaternized (2-dimethylamino)ethyl methacrylate. The hydrophobic MMMs were prepared by the addition of iron oxide nanoparticles with different surface properties to a linear poly (methacrylic acid)-b-poly (methylmethacrylate) diblock copolymer dissolved in tetrahydrofuran (THF). Three different types of hydrophilic membranes were prepared with polymeric nanoparticles of different morphologies (spherical, vermicular and vesicular). In case of the hydrophobic membranes, six different membranes containing different iron oxide core coated with different stabilizers such as poly (methacrylic acid), quaternized poly(2-dimethylamino)ethyl methacrylate and meso-2, 3-dimercaptosuccinic acid were prepared. An external magnetic field with intensity values up to 1.15 T was used for the permeation studies and the results were compared with those obtained in the absence of magnetic field. The collected data indicate an increase in the water flux of up to 16% and 29% under the magnetic field for hydrophobic and hydrophilic membranes, respectively. The STEM analyses suggest that the magnetic nanoparticles move within the membrane structure during the application of the magnetic field. This displacement/rearrangement causes constant changes in the membrane structure (structure of the active layer) and consequently on the membrane permeability. These results suggest that the application of the magnetic field could be used as a pretreatment step to obtain high flux membranes

Low-temperature dynamics of the Curie-Weiss Model: Periodic orbits, multiple histories, and loss of Gibbsianness

We consider the Curie-Weiss model at a given initial temperature in vanishing external field evolving under a Glauber spin-flip dynamics corresponding to a possibly different temperature. We study the limiting conditional probabilities and their continuity properties and discuss their set of points of discontinuity (bad points). We provide a complete analysis of the transition between Gibbsian and non-Gibbsian behavior as a function of time, extending earlier work for the case of independent spin-flip dynamics. For initial temperature bigger than one we prove that the time-evolved measure stays Gibbs forever, for any (possibly low) temperature of the dynamics. In the regime of heating to low-temperatures from even lower temperatures, when the initial temperature is smaller than the temperature of the dynamics, and smaller than 1, we prove that the time-evolved measure is Gibbs initially and becomes non-Gibbs after a sharp transition time. We find this regime is further divided into a region where only symmetric bad configurations exist, and a region where this symmetry is broken. In the regime of further cooling from low-temperatures there is always symmetry-breaking in the set of bad configurations. These bad configurations are created by a new mechanism which is related to the occurrence of periodic orbits for the vector field which describes the dynamics of Euler-Lagrange equations for the path large deviation functional for the order parameter. To our knowledge this is the first example of the rigorous study of non-Gibbsian phenomena related to cooling, albeit in a mean-field setup.Comment: 31 pages, 24 figure

Epidemiología y pronóstico de los pacientes con VIH ingresados en la UCI en la era de tratamiento antirretroviral de gran actividad actual

Observational study[Abstract] Purpose: To describe the epidemiology of critical disease in HIV-infected patients during the current highly active antiretroviral therapy (HAART) era and to identify hospital mortality predictors. Methods: A longitudinal, retrospective observational study was made of HIV-infected adults admitted to the ICU in two Spanish hospitals between 1 January 2000 and 31 December 2014. Demographic and HIV-related variables were analyzed, together with comorbidities, severity scores, reasons for admission and need for organ support. The chi-squared test was used to compare categorical variables, while continuous variables were contrasted with the Student's t-test, Mann-Whitney U-test or Kruskal-Wallis test, assuming an alpha level=0.05. Multivariate logistic regression analysis was used to calculate odds ratios for assessing correlations to mortality during hospital stay. Joinpoint regression analysis was used to study mortality trends over time. Results: A total of 283 episodes were included for analyses. Hospital mortality was 32.9% (95%CI: 21.2-38.5). Only admission from a site other than the Emergency Care Department (OR 3.64, 95%CI: 1.30-10.20; p=0.01), moderate-severe liver disease (OR 5.65, 95%CI: 1.11-28.87; p=0.04) and the APACHE II score (OR 1.14, 95%CI: 1.04-1.26; p<0.01) and SOFA score at 72h (OR 1.19, 95%CI: 1.02-1.40; p=0.03) maintained a statistically significant relationship with hospital mortality. Conclusions: Delayed ICU admission, comorbidities and the severity of critical illness determine the prognosis of HIV-infected patients admitted to the ICU. Based on these data, HIV-infected patients should receive the same level of care as non-HIV-infected patients, regardless of their immunological or nutritional condition.[Resumen] Objetivos. Describir la epidemiología de la patología crítica en el paciente infectado por VIH durante la era de tratamiento antirretroviral de gran actividad actual y encontrar predictores de mortalidad hospitalaria. Métodos. Estudio observacional, retrospectivo y longitudinal que incluye pacientes infectados por VIH adultos ingresados en las UCI de hospitales de Galicia, entre el 1 de enero de 2000 y el 31 de diciembre de 2014. Analizamos variables demográficas y relacionadas con la infección por el VIH, comorbilidades, puntuaciones de gravedad, motivo de ingreso y necesidad de soporte de órganos. Empleamos la prueba de la Chi-cuadrado para comparar las variables categóricas y las pruebas de la T-Student, U de Mann-Whitney o H de Kruskal-Wallis para las variables continuas, asumiendo un error α = 0,05. Utilizamos la regresión logística multivariante para calcular la OR de la asociación con la mortalidad hospitalaria. Aplicamos análisis de regresión de joinpoint para estudiar la tendencia temporal de mortalidad. Resultados. Incluimos 283 episodios. La mortalidad hospitalaria fue del 32,9% (IC 95% = 21,2-38,5%). El ingreso no procedente de Urgencias (OR 3,64; IC 95% = 1,30-10,20; p = 0,01), la enfermedad hepática moderada-grave (OR 5,65; IC 95% = 1,11-28,87; p = 0,04), el APACHE II (OR 1,14; IC 95% = 1,04-1,26; p < 0,01) y el SOFA a las 72 h (OR 1,19; IC 95% = 1,02-1,40; p = 0,03) se relacionan con la mortalidad hospitalaria en el análisis multivariante. Conclusiones. El retraso en el ingreso en UCI, las comorbilidades y la gravedad del episodio determinan el pronóstico del paciente infectado por VIH ingresado en UCI. Los pacientes con VIH deberían recibir el mismo nivel de cuidados que los pacientes no infectados por VIH, independientemente de su estado inmunológico o nutricional

Extensions of the matrix Gelfand-Dickey hierarchy from generalized Drinfeld-Sokolov reduction

The $p\times p$ matrix version of the $r$-KdV hierarchy has been recently treated as the reduced system arising in a Drinfeld-Sokolov type Hamiltonian symmetry reduction applied to a Poisson submanifold in the dual of the Lie algebra $\widehat{gl}_{pr}\otimes {\Complex}[\lambda, \lambda^{-1}]$. Here a series of extensions of this matrix Gelfand-Dickey system is derived by means of a generalized Drinfeld-Sokolov reduction defined for the Lie algebra $\widehat{gl}_{pr+s}\otimes {\Complex}[\lambda,\lambda^{-1}]$ using the natural embedding $gl_{pr}\subset gl_{pr+s}$ for $s$ any positive integer. The hierarchies obtained admit a description in terms of a $p\times p$ matrix pseudo-differential operator comprising an $r$-KdV type positive part and a non-trivial negative part. This system has been investigated previously in the $p=1$ case as a constrained KP system. In this paper the previous results are considerably extended and a systematic study is presented on the basis of the Drinfeld-Sokolov approach that has the advantage that it leads to local Poisson brackets and makes clear the conformal ($\cal W$-algebra) structures related to the KdV type hierarchies. Discrete reductions and modified versions of the extended $r$-KdV hierarchies are also discussed.Comment: 60 pages, plain TE

Results from the application of new active methodologies for the toxicology subject learning

Con el fin de adaptar la asignatura de Toxicología (tercer curso) a los nuevos planes de estudio europeos del Grado de Farmacia, se han introducido nuevas metodologías activas basadas principalmente en el trabajo personal y en la participación del alumno en el proceso de enseñanza aprendizaje. La introducción de las nuevas metodologías activas tiene como objetivos un aumento de la capacidad de síntesis, análisis y esquematización por parte del alumnado, un aumento de la participación y del trabajo en grupo y la formación en competencias como el manejo de fuentes bibliográficas y la búsqueda de información. El fin último es mejorar la calidad de la docencia aumentando el interés de los alumnos por los conocimientos adquiridos mediante una forma de enseñanza más participativa, dinámica y práctica que además relacione los contenidos teóricos con la práctica en un futuro profesional aportando al alumno una visión más cercana a la realidad. Para incentivar la participación de forma voluntaria por parte del alumno se ha propuesto la realización de una de dos posibles actividades independientes, pero complementarias: 1) preparación de tres temas inéditos en pregrado y 2) resolución de dos problemas (ABP) para lo que tuvieron que aplicar conocimientos adquiridos en clases teóricas. Éstas se realizaron de forma tutorizada y supervisada por los profesores del Área. Además se contó positivamente la asistencia a clases teóricas y a dos conferencias impartidas por expertos en las áreas de Toxicología Forense y de Toxicología Alimentaria. La valoración de la experiencia ha sido positiva ya que se consiguió un aumento de la asistencia a clase y de la participación por parte de los alumnos, todo ello además se vio reflejado en una mejora de las calificaciones obtenidas.In order to adapt the subject of Toxicology to the new curricula in Europe, new active methodologies have introduced. They are mainly based in personal work and student participation in the process of teaching-learning. The introduction of new active methodologies aims to increase the capacity for synthesis, analysis and schematize in our students, as well as to increase its participation and group work and training in skills such as handling and searching bibliographical sources information. The ultimate goal is to improve the quality of teaching by increasing students' interest for knowledge gained through a more participatory form of education, dynamic and practical. In addition, students would be asked to interrelating theory contents with future professional practice by providing students a closer vision to reality. To encourage voluntary participation by the student, it was proposed to perform one of two independent but complementary activities: a) preparation of three new lessons in undergraduate classes; and 2) resolution of two problems (ABP) for what they had to apply theoretical knowledge acquired. These were carried out tutored and supervised by teachers of the area. In addition, attendance to theory classes and to lectures given by experts in the fields of Forensic Toxicology and Food was positively marked. The assessment of the experience was positive because an increase in class attendance and participation by students was achieved, which was also reflected in an improvement in grades

The Cerenkov effect revisited: from swimming ducks to zero modes in gravitational analogs

We present an interdisciplinary review of the generalized Cerenkov emission of radiation from uniformly moving sources in the different contexts of classical electromagnetism, superfluid hydrodynamics, and classical hydrodynamics. The details of each specific physical systems enter our theory via the dispersion law of the excitations. A geometrical recipe to obtain the emission patterns in both real and wavevector space from the geometrical shape of the dispersion law is discussed and applied to a number of cases of current experimental interest. Some consequences of these emission processes onto the stability of condensed-matter analogs of gravitational systems are finally illustrated.Comment: Lecture Notes at the IX SIGRAV School on "Analogue Gravity" in Como, Italy from May 16th-21th, 201

Investigating the effect of GaCl3 incorporation into the usual CdCl2 treatment on CdTe-based solar cell device structures

The incorporation of GaCl3 into the usual CdCl2 post-deposition treatment solution of CdTe-based solar cells has been investigated. Both CdS and CdTe layers used in this work were prepared by electroplating technique and they are n-type in electrical conduction as observed from photoelectrochemical cell measurement technique. Before applying the chemical treatments to the device structures, the effect of GaCl3 incorporation into the usual CdCl2 treatment was first studied on the structural and optical properties of CdTe thin films. The results of the optical properties show that the bandgap of CdTe thin films treated with a mixture of GaCl3 + CdCl2 is closer to that of bulk CdTe layers than the ones treated only with CdCl2 solution. The structural properties also showed that CdTe thin films treated with GaCl3 + CdCl2 is more crystalline than CdTe thin films treated only with CdCl2 solution. The addition of GaCl3 into the CdCl2 solution have been seen to drastically enhance the solar-to-electric conversion efficiency of CdS/CdTe based solar cells. One of the effects of Ga incorporation into the usual CdCl2 treatment was seen in the series resistance reduction which ultimately leads to enhancement in the observed short-circuit current density, fill factor and overall solar cell efficiency. For the glass/FTO/n-CdS/n-CdTe device structures, the cell efficiencies were observed in the range 1.9–2.1% after being treated with CdCl2 solution only. When treated with CdCl2 + GaCl3, the efficiency increased to 6.1–6.4%. Subsequent study on multi-junction graded bandgap solar cells using the GaCl3 + CdCl2 chemical solution for the surface treatment of glass/FTO/n-ZnS/n-CdS/n-CdTe device structures results in solar cell efficiency >10%