Enhancing Polymer Blend Compatibility with Linear and Complex Star Copolymer Architectures: A Monte Carlo Simulation Study with the Bond Fluctuation Model.

A Monte Carlo study of the compatibilization of A/B polymer blends has been performed using the bond fluctuation model. The considered compatibilizers are copolymer molecules composed of A and B blocks. Different types of copolymer structures have been included, namely, linear diblock and 4-block alternating copolymers, star block copolymers, miktoarm stars, and zipper stars. Zipper stars are composed of two arms of diblock copolymers arranged in alternate order (AB and BA) from the central unit, along with two homogeneous arms of A and B units. The compatibilization performance has been characterized by analyzing the equilibration of repulsion energy, the simulated scattering intensity obtained with opposite refractive indices for A and B, the profiles along a coordinate axis, the radial distribution functions, and the compatibilizer aggregation numbers. According to the results, linear alternate block copolymers, star block copolymers, and zipper stars exhibit significantly better compatibilization, with zipper stars showing slightly but consistently better performance.

Simulation of Nondilute Dendrimer Systems with the Bond Fluctuation Model.

Using the bond fluctuation model, we performed Monte Carlo simulations for solutions of generation 4 and 5 dendrimers with only an intermediate unit between the branching points at different concentrations, ranging from moderately dilute solutions to concentrated systems close to the melt behavior. This model may represent different real types of dendrimer families. We obtained the mean sizes, asphericities, displacement of units, scattering functions, radial distribution functions and structure factors. We compared the results obtained for the last two properties with much faster Monte Carlo simulations of point-like dendrimers using global potentials obtained through the study of binary interactions. The latter procedure provided good reproductions of these properties but failed in the reproduction of the scattering functions in the range of higher concentrations. In this range, the scattering function cannot be described as the product of the structure function and the form factor, because the intensity decreases when the density of the dendrimer units becomes more homogenous.

Study of Segregation in Non-Dilute Solutions of Linear Diblock Copolymers and Symmetric Miktoarm (or Janus Star) Polymers Using Monte Carlo Simulations with the Bond Fluctuation Model.

The bond fluctuation model was employed to characterize the approach to the mesophase separation transition of pure linear AB copolymers and symmetric miktoarms, also called Janus, star polymers, Af/2Bf/2 , where f = 6 or 12 is the total number of arms, in a common good solvent. We consider a concentration sufficiently high to mimic the melting behavior and also a lower concentration. The segregation between A and B units is represented by a repulsive interaction parameter, . Different total numbers of units are also considered. Results for different properties, such as the molecular size, the asphericity and orientational correlation of blocks, or arms, of different compositions are obtained as a function of the segregation parameter. We also calculate scattering structure factors. The initial effect of segregation on the scattering with opposite contrast factors between the A and B blocks can be explained with a common description based on the random phase approximation for both the linear copolymers and the f = 6 miktoarms, once the numerical form factors of the different molecules in their particular systems are considered. However, the results for f = 12 clearly deviate from this description probably due to some degree of ordering in the position of highly armed molecules.

Tratamiento y manejo fibrinolítico en síndrome de Nicolau: Caso clínico / Fibrinolytic treatment and management in Nicolau syndrome: Clinical case

RESUMEN Introducción: El síndrome de Nicolau (SN), conocido como embolia cutis medicamentosa o dermatitis livedoide es un acontecimiento adverso debido a la administración de inyecciones intramusculares, intraarteriales, subcutánea e incluso intraarticulares asociado a diversos fármacos1. Se desconoce toda la patogenia de este síndrome, pero se ha asociado a lesión vascular, trombosis arterial, espasmo reflejo de las arterias, oclusión vascular por microembolia e inflamación. Caso clínico: Paciente masculino de 32 años de edad, luego de inyección intramuscular de penicilina benzatínica presenta dolor intenso en área de inyección que se acompaña de lesiones eritematosas a nivel de abdomen, escroto y miembro inferior derecho además de presentar dolor, pareste-sia, palidez moteado eritematoso (livedo) y disminución de pulsos en dicha extremidad por lo que se diagnostica isquemia aguda (IA) que requirió tratamien-to fibrinolitico, entre otros fármacos. Conclusión: El síndrome de Nicolau es una condición iatrogénica que puede ser producida por inyección de múltiples medicamentos, puede presentar diferentes síntomas y signos como lesión neurológica, necrosis en área de irrigación de vasos afectados e incluso isquemia aguda. En este caso el manejo con rt-PA fue efectivo en tratar la isquemia. El conocimiento de este síndrome y sus complicaciones facilitaría su manejo2.Palabras claves: Síndrome Nicolau, bencilpenicilina, anticoagulante, rt-PA

ABSTRACT Introduction: Nicolau syndrome (NS), known as cutaneous embolism or livedoid dermatitis, is an adverse event due to the administration of intramuscular, intraarterial, subcutaneous and intraarticular injections associated with various drugs1. The entire pathogenesis of this syndrome is unknown, but it has been associated with vascular injury, arterial thrombosis, reflex spasm of the arteries, vascular occlusion due to microemboli, and inflammation. Clinical case: 32-year-old male. After an intramuscular injection of benzathine penicillin, the patient presented severe pain in the injection area accompanied by erythem-atous lesions at the level of the abdomen, scrotum, and right lower limb. In addition to that, the patient presented pain, paresthesia, and mottled paleness erythema (livedo). Moreover, the patient had a decreased pulse in the right limb, acute ischemia was diagnosed and required fibrinolitic treatment, among other drugs. Conclusion: Nicolau Syndrome, is an iatrogenic condition that is produced by injection of multiple drugs. It can produce different symptoms and signs from neurological injury, necrosis in the irrigation area of affected vessels and acute ischemia. rt-PA management in this case was effective in treating ischemia. It is essential to know about this syndrome and its complications. This would facilitate its management2.Keywords: Nicolau syndrome, benzylpenicillin, anticoagulant, rt-PA.

Cinco complicaciones comunes en heridas quirúrgicas: prevención y manejo.

Five common complications with surgical wounds: prevention and management On 3 September 2020, at the Semana HEI virtual conference, vascular surgeon Juan Francisco Benalcázar Freire, from Hospital de Especialidades de las Fuerzas Armadas in Quito, Ecuador, presented a webinar describing the most common issues when facing surgical wounds. In this report, Dr Benalcázar summarises the key take-away messages from his talk and encourages health professionals not to focus on surgical site infection (SSI) alone, but also on other five common complications in surgical wounds.

SINOPSIS: El 3 de septiembre de 2020, durante la conferencia virtual Semana HEI (heridas, estomas e incontinencias), el cirujano vascular Juan Francisco Benalcázar Freire, del Hospital de Especialidades de las Fuerzas Armadas en Quito, Ecuador, presentó un webinar que describió las complicaciones más frecuentes en heridas quirúrgicas. En este reporte, el Dr Benalcázar resume los puntos más relevantes de su ponencia y alienta a los profesionales de la salud a enfocarse no sólo en la profilaxis de la infección del sitio quirúrgico, sino también en los cinco problemas más comunes de la herida quirúrgica. CONFLICTO DE INTERÉS: JFBF ha trabajado como presentador en conferencias organizadas o auspiciadas por Essity.

Multispecies Fisheries in the Lower Amazon River and Its Relationship with the Regional and Global Climate Variability.

This paper aims to describe the spatial-temporal variability in catch of the main fishery resources of the Amazon River and floodplain lakes of the Lower Amazon, as well as relating the Catch per Unit of Effort with anomalies of some of the Amazon River, atmosphere and Atlantic Ocean system variables, determining the influence of the environment on the Amazonian fishery resources. Finfish landings data from the towns and villages of the Lower Amazon for the fisheries of three sites (Óbidos, Santarém and Monte Alegre), were obtained for the period between January 1993 and December 2004. Analysis of variance, detrended correspondence analysis, redundancy analysis and multiple regression techniques were used for the statistical analysis of the distinct time series. Fisheries production in the Lower Amazon presents differences between the Amazon River and the floodplain lakes. Production in the Amazon River is approximately half of the one of the floodplain lakes. This variability occurs both along the Lower Amazon River region (longitudinal gradient) and laterally (latitudinal gradient) for every fishing ground studied here. The distinct environmental variables alone or in association act differently on the fishery stocks and the success of catches in each fishery group studied here. Important variables are the flooding events; the soil the sea surface temperatures; the humidity; the wind and the occurence of El Niño-Southern Oscillation events. Fishery productivity presents a large difference in quantity and distribution patterns between the river and floodplain lakes. This variability occurs in the region of the Lower Amazon as well as laterally for each fishery group studied, being dependent on the ecological characteristics and life strategies of each fish group considered here.

The key role of the Barefoot Fisheries Advisors in the co-managed TURF system of Galicia (NW Spain).

Many authors have pointed out the need for simpler assessment and management procedures for avoiding overexploitation in small-scale fisheries. Nevertheless, models for providing scientific advice for sustainable small-scale fisheries management have not yet been published. Here we present one model; the case of the Barefoot Fisheries Advisors (BFAs) in the Galician co-managed Territorial Users Rights for Fishing. Based on informal interviews, gray literature and our personal experience by being involved in this process, we have analyzed the historical development and evolution of roles of this novel and stimulating actor in small-scale fisheries management. The Galician BFA model allows the provision of good quality and organized fisheries data to facilitate and support decision-making processes. The BFAs also build robust social capital by acting as knowledge collectors and translators between fishers, managers, and scientists. The BFAs have become key actors in the small-scale fisheries management of Galicia and a case for learning lessons.

Molecular dynamics simulations of the protonated G4 PAMAM dendrimer in an ionic liquid system.

Molecular dynamics simulations have been carried out for the ionic liquid system constituted by totally protonated PAMAM-EDA cations and Tf2N(-) anions. The conformational characteristics of the PMAM dendrimer (particularly the density profile around the dendrimer center) are compared with those obtained for the same dendrimer in water. We also investigate other features, such as the location of anions relative to the dendrimer molecules, and the interpenetration of the dendrimer cations in the ionic liquid system. It is shown that a substantial amount of anions are present in the outer part of the dendrimer, screening repulsive contacts between different cation molecules and favoring ionic conductivity. Dendrimer cations in the ionic liquid exhibit a significant degree of overlap.

The conservation and management of tunas and their relatives: setting life history research priorities.

Scombrids (tunas, bonitos, Spanish mackerels and mackerels) support important fisheries in tropical, subtropical and temperate waters around the world, being one of the most economically- and socially-important marine species globally. Their sustainable exploitation, management and conservation depend on accurate life history information for the development of quantitative fisheries stock assessments, and in the fishery data-poor situations for the identification of vulnerable species. Here, we assemble life history traits (maximum size, growth, longevity, maturity, fecundity, spawning duration and spawning interval) for the 51 species of scombrids globally. We identify major biological gaps in knowledge and prioritize life history research needs in scombrids based on their biological gaps in knowledge, the importance of their fisheries and their current conservation status according to the International Union for Conservation of Nature Red List. We find that the growth and reproductive biology of tunas and mackerel species have been more extensively studied than for Spanish mackerels and bonitos, although there are notable exceptions in all groups. We also reveal that reproductive biology of species, particular fecundity, is the least studied biological aspect in scombrids. We identify two priority groups, including 32 species of scombrids, and several populations of principal market tunas, for which life history research should be prioritized following the species-specific life history gaps identified in this study in the coming decades. By highlighting the important gaps in biological knowledge and providing a priority setting for life history research in scombrid species this study provides guidance for management and conservation and serves as a guide for biologists and resource managers interested in the biology, ecology, and management of scombrid species.

Assessing the spatial variability, level and source of organic chemical contaminants in bivalve fishing grounds on the Galician coast (NW Spain).

Polychlorinated biphenyls, organochlorine pesticides, organotin compounds and triazines were quantified in sediments and bivalves collected in four areas on the Galician coast. One or several species were analysed at each site depending on their availability, including mussels (Mytilus galloprovincialis), cockles (Cerastoderma edule), clams (Venerupis pullastra and Ruditapes decussatus) and razor shells (Ensis siliqua). The general spatial distribution of contaminants was consistent in spite of the different sources of contamination. High inter-species variability was also observed. M. galloprovincialis and V. pullastra showed the highest levels of contaminants and intra-spatial variability, which highlights them as suitable species to be used as sentinel organisms. The area of O Burgo showed some worrisome results: PCB sediment concentrations were within the range that could cause biological effects. Also the level of heptachlor observed in V. pullastra was above limits accepted on edible seafood. Finally TBT concentration in mussels correlated with concentrations causing imposex in snails.

Global population trajectories of tunas and their relatives.

Tunas and their relatives dominate the world's largest ecosystems and sustain some of the most valuable fisheries. The impacts of fishing on these species have been debated intensively over the past decade, giving rise to divergent views on the scale and extent of the impacts of fisheries on pelagic ecosystems. We use all available age-structured stock assessments to evaluate the adult biomass trajectories and exploitation status of 26 populations of tunas and their relatives (17 tunas, 5 mackerels, and 4 Spanish mackerels) from 1954 to 2006. Overall, populations have declined, on average, by 60% over the past half century, but the decline in the total adult biomass is lower (52%), driven by a few abundant populations. The trajectories of individual populations depend on the interaction between life histories, ecology, and fishing pressure. The steepest declines are exhibited by two distinct groups: the largest, longest lived, highest value temperate tunas and the smaller, short-lived mackerels, both with most of their populations being overexploited. The remaining populations, mostly tropical tunas, have been fished down to approximately maximum sustainable yield levels, preventing further expansion of catches in these fisheries. Fishing mortality has increased steadily to the point where around 12.5% of the tunas and their relatives are caught each year globally. Overcapacity of these fisheries is jeopardizing their long-term sustainability. To guarantee higher catches, stabilize profits, and reduce collateral impacts on marine ecosystems requires the rebuilding of overexploited populations and stricter management measures to reduce overcapacity and regulate threatening trade.

Force field parametrization and molecular dynamics simulation of flexible POSS-linked (NHC; phosphine) Ru catalytic complexes.

In recent years, N-heterocyclic carbene (NHC) or phospine groups have been put forward as candidate catalysts ligands for olefin metathesis reactions to be performed using multistep methods. Some of these proposed ligands contain polyhedral oligomeric silsesquioxane (POSS) structures linked to NHC rings by means of alkyl chains. Some important properties for the prediction of catalytic activity, such as the theoretically defined buried volume, are related to the conformational characteristics of these complex ligands that can be studied through molecular dynamics simulations. However, the chemical structure of resulting catalytic complexes usually contains atoms or groups that are not included in the common forcefields used in simulations. In this work we focus on complexes formed by a catalytic metal center (Ru) with both phospine and POSS-linked NHC groups. The central part of the complexes contain atoms and groups that have bonds, bond angles, and torsional angles whose parameters have not been previously evaluated and included in existing force fields. We have performed basic ab initio quantum mechanical calculations based on the density functional theory to obtain energies for this central section. The force field parameters for bonds, bond angles, and torsional angles are then calculated from an analysis of energies calculated for the equilibrium and different locally deformed structures. Nonbonded interactions are also conveniently evaluated. From subsequent molecular dynamics simulations, we have obtained results that illustrate the conformational characteristics most closely connected with the catalytic activity.

EROD activity and stable isotopes in seabirds to disentangle marine food web contamination after the Prestige oil spill.

In this study, we measured via surgical sampling hepatic EROD activity in yellow-legged gulls from oiled and unoiled colonies, 17 months after the Prestige oil spill. We also analyzed stable isotope composition in feathers of the biopsied gulls, in an attempt to monitor oil incorporation into marine food web. We found that yellow-legged gulls in oiled colonies were being exposed to remnant oil as shown by hepatic EROD activity levels. EROD activity was related to feeding habits of individual gulls with apparent consequences on delayed lethality. Capture-recapture analysis of biopsied gulls suggests that the surgery technique did not affect gull survival, giving support to this technique as a monitoring tool for oil exposure assessment. Our study highlights the combination of different veterinary, toxicological and ecological methodologies as a useful approach for the monitoring of exposure to remnant oil after a large oil spill.

Genetic characterization of Venezuelan equine encephalitis virus from Bolivia, Ecuador and Peru: identification of a new subtype ID lineage.

Venezuelan equine encephalitis virus (VEEV) has been responsible for hundreds of thousands of human and equine cases of severe disease in the Americas. A passive surveillance study was conducted in Peru, Bolivia and Ecuador to determine the arboviral etiology of febrile illness. Patients with suspected viral-associated, acute, undifferentiated febrile illness of <7 days duration were enrolled in the study and blood samples were obtained from each patient and assayed by virus isolation. Demographic and clinical information from each patient was also obtained at the time of voluntary enrollment. In 2005-2007, cases of Venezuelan equine encephalitis (VEE) were diagnosed for the first time in residents of Bolivia; the patients did not report traveling, suggesting endemic circulation of VEEV in Bolivia. In 2001 and 2003, VEE cases were also identified in Ecuador. Since 1993, VEEV has been continuously isolated from patients in Loreto, Peru, and more recently (2005), in Madre de Dios, Peru. We performed phylogenetic analyses with VEEV from Bolivia, Ecuador and Peru and compared their relationships to strains from other parts of South America. We found that VEEV subtype ID Panama/Peru genotype is the predominant one circulating in Peru. We also demonstrated that VEEV subtype ID strains circulating in Ecuador belong to the Colombia/Venezuela genotype and VEEV from Madre de Dios, Peru and Cochabamba, Bolivia belong to a new ID genotype. In summary, we identified a new major lineage of enzootic VEEV subtype ID, information that could aid in the understanding of the emergence and evolution of VEEV in South America.

A multiscale scheme for the simulation of conformational and solution properties of different dendrimer molecules.

We propose a multiscale protocol for the simulation of conformation and dynamics of dendrimer molecules in dilute solution. Conformational properties (radius of gyration, mass distribution, and scattering intensities) and overall hydrodynamic properties (translational diffusion and intrinsic viscosity) are predicted by means of a very simple coarse-grained bead-and-spring model, whose parameters are not adjusted against experimental properties, but rather they are obtained from previous, atomic-level simulations which are also quite simple, performed with small fragments and Langevin dynamics simulation. The scheme is described and applied systematically to four different dendrimer molecules with up to seven generations. The predictive capability of this scheme is tested by comparison with experimental data. It is found that the predicted geometric and hydrodynamic radii of the dendrimer molecules are in agreement (typical error is about 4%) with a large set experimental values of the four dendrimers with various numbers of generations. Agreement with some X-ray scattering experimental intensities also confirms the good prediction of the internal structure. This scheme is easily extendable to study more complex molecules (e.g., functionalized dendrimers) and to simulate internal dynamics.

Escala de actitud favorable hacia la violación: primeras evidencias acerca de su fiabilidad y validez en muestras salvadoreñas / Rape supportive attitude scale: first evidence on its reliability and validity in the salvadorian samples

Las actitudes tolerantes hacia la violencia sexual ejercida contra las mujeres constituyen un factor de riesgo importante a considerar en la explicación de este tipo de conductas agresivas. Uno de los instrumentos para evaluar estas actitudes es la Escala de Actitud Favorable hacia la Violación (EAFV) de Lottes, la cual ha mostrado buenos índices de fiabilidad y validez, tanto en muestras de estudiantes universitarios estadounidenses como españoles. El objetivo de este estudio es explorar sus características psicométricas en El Salvador, para lo cual fue aplicada conjuntamente con la Escala de Doble Moral de Caron, Davis, Haltelman y Stickle (1993) y la Escala de Deseabilidad Social de Crowne y Marlowe (1960) a dos muestras de 505 y 1.499 estudiantes universitarios, respectivamente. Los resultados indican que la estructura unidimensional de la escala se mantiene estable en las dos muestras, alcanzando coeficientes de consistencia interna superiores a 0.80, aunque incluye dos ítems que requieren de una revisión en futuros estudios. En cuanto a la validez, la EAFV es capaz de diferenciar a hombres y mujeres en este tipo de actitudes, y muestra una correlación positiva significativa con la doble moral sexual.

The tolerant attitudes towards sexual violence on women are important risk factor which should be considered whileexplaining this type of aggressive behaviour. One of the instruments to evaluate these attitudes is Rape Supportive Attitude Scale (RSAS) by Lottes. The scale has showed good indexes of reliability and validity in both American and Spanish university students. The purpose of the study is to explore the psychometric characteristics in El Salvador as it has been applied together with the Double Standard Scale by Caron, Davis, Haltelman and Stickle (1993) and Crowne and Marlowe (1960) Social Desirability Scale in two samples which consisted of 505 and 1499 students, respectively. The results indicate that the one-dimensional structure of the scale stays stable in the two samples reaching the coefficients of internal consistence higher than .80, although it includes two items which requires to be reviewed in future studies. Concerning the validity, the RSAS differentiates men and women in these types of attitudes and shows significant positive correlation with double sexual standard.

Monte Carlo calculations for the intrinsic viscosity of several dendrimer molecules.

We have performed Monte Carlo simulations to reproduce the intrinsic viscosity corresponding to different generation of several types of dendrite molecules: polyamidoamine dendrimers with an ethylendiamine core, polypropylene-imine with a diaminobutane core, and monodendrons and tridendrons of polybenzylether. With this end, we have employed coarse-grained idealizations of the molecules constituted by only two beads in each repeat unit (one in a branching or end unit and one intermediate along the repeat unit) and a simple hard-sphere potential between non-neighboring beads. Our goal is to investigate if this simple model is able to provide a reasonable description of some differences between these systems that have been observed experimentally, in particular, the location of the maximum in the intrinsic viscosity as a function of the generation number. Experimental radii of gyration in a given solvent are reproduced by a fit of the hard-sphere potential diameter. Subsequently, intrinsic viscosities are calculated by the variational approach of Fixman, which yields an accurate lower-bound value with an additional hydrodynamic interaction parameter (the friction radius of the beads). The results show a pronounced variation of the maximum location with the value of the friction radius and the structural details that cannot be mimicked with simpler models. The initial conformations for the Monte Carlo procedure are taken from atomistic configurations thermalized by means of a molecular dynamics.

Sépsis en fracturas expuestas: factores determinantes / Sépsis in exposed fractures: determining factors

Las fracturas expuestas son una entidad patológica muy frecuente en nuestro medio, sobre todo en el área urbana y en menor proporción en el área rural. La infección en las fracturas expuestas, continúa siendo un gran problema de la especialidad traumatológica, lo cual repercute desde el punto de vista económico y social tanto en el núcleo familiar como en las políticas de salud estatales. Por este motivo el objetivo del presente estudio es determinar la eficacia de la atención primaria, la agilidad de la misma, la eficacia del procedimiento quirúrgico realizado y del manejo antibiótico suministrado. Por este motivo realizamos el presente estudio en los Hospitales Eugenio Espejo, Baca Ortíz, Pablo Arturo Suárez, General de las FF.AA del Ecuador de Quito y en el Hospital Universitario del Valle (Cali-Colombia). El número de pacientes iingresados en Quito fue de 64 casos y en Cali 26 casos...

Incidencia y prevalencia de infección de vías urinarias Hospital Provincial de Cotopaxi / Incidence and prevalence of infection of urinary channels Provincial Hospital of Cotopaxi

Estudia la incidencia de infección de vías urinarias, en pacientes atendidos en el Hospital Provincial de Cotopaxi. En un país como el nuestro es de mucha utilidad el conocer la frecuencia con que se presenta la infección del tracto urinario, puesto que a la postre puede constituirse en un problema de salud de la población. Con esto se ha estudiado una población específica recopilada de las historias clínicas de 1987 a 1991. Se analizan variables como: edad, sexo, situación socioeconómica, lugar de procedencia, el diagnóstico hecho con laboratorio o sin él, y las principales manifestaciones clínicas; además de prevalencia por sexo y grupos etáreos. Observaciones que existen mayor prevalencia de infección de vías urinarias en el sexo femenino y la edad comprendida que coincide con la época fértil y vida sexual activa en la mujer...

Estudio sobre egresos hospitalarios de diabetes mellitus en el Hospital Provincial de Cotopaxi / Study on hospitable debits of diabetes mellitus in the Provincial Hospital of Cotopaxi

Presenta un estudio retrospectivo cualicuantitativo de 46 pacientes cuyo diagnóstico de egreso fue diabetes mellitus entre ene. 1987 y mar. 1992, utilizan la información tomada de las fichas médicas que reposan en el Departamento de Estadística del Hospital Provincial de Cotopaxi, observándose que en un 0.85xciento de la población total de pacientes de dicho hospital tienen diabetes mellitus, que la de tipo II es más frecuente que la de tipo I en una relación de 2.83 a 1. El 100xciento de diabetes tipo I son insulinodependientes y que afecta a la población jóven; los pacientes de tipo II se controlan en su mayoría con antidiabéticos orales y dieta...