Showing papers by "Simón Bolívar University published in 2016"

Co-benefits of addressing climate change can motivate action around the world

Abstract: Personal and political action on climate change is traditionally thought to be motivated by people accepting its reality and importance. However, convincing the public that climate change is real faces powerful ideological obstacles1, 2, 3, 4, and climate change is slipping in public importance in many countries5, 6. Here we investigate a different approach, identifying whether potential co-benefits of addressing climate change7 could motivate pro-environmental behaviour around the world for both those convinced and unconvinced that climate change is real. We describe an integrated framework for assessing beliefs about co-benefits8, distinguishing social conditions (for example, economic development, reduced pollution or disease) and community character (for example, benevolence, competence). Data from all inhabited continents (24 countries; 6,196 participants) showed that two co-benefit types, Development (economic and scientific advancement) and Benevolence (a more moral and caring community), motivated public, private and financial actions to address climate change to a similar degree as believing climate change is important. Critically, relationships were similar for both convinced and unconvinced participants, showing that co-benefits can motivate action across ideological divides. These relationships were also independent of perceived climate change importance, and could not be explained by political ideology, age, or gender. Communicating co-benefits could motivate action on climate change where traditional approaches have stalled.

Co-benefits of addressing climate change can motivate action around the world

Abstract: Personal and political action on climate change is traditionally thought to be motivated by people accepting its reality and importance. However, convincing the public that climate change is real faces powerful ideological obstacles1, 2, 3, 4, and climate change is slipping in public importance in many countries5, 6. Here we investigate a different approach, identifying whether potential co-benefits of addressing climate change7 could motivate pro-environmental behaviour around the world for both those convinced and unconvinced that climate change is real. We describe an integrated framework for assessing beliefs about co-benefits8, distinguishing social conditions (for example, economic development, reduced pollution or disease) and community character (for example, benevolence, competence). Data from all inhabited continents (24 countries; 6,196 participants) showed that two co-benefit types, Development (economic and scientific advancement) and Benevolence (a more moral and caring community), motivated public, private and financial actions to address climate change to a similar degree as believing climate change is important. Critically, relationships were similar for both convinced and unconvinced participants, showing that co-benefits can motivate action across ideological divides. These relationships were also independent of perceived climate change importance, and could not be explained by political ideology, age, or gender. Communicating co-benefits could motivate action on climate change where traditional approaches have stalled.

ARIA 2016: Care pathways implementing emerging technologies for predictive medicine in rhinitis and asthma across the life cycle

Abstract: The Allergic Rhinitis and its Impact on Asthma (ARIA) initiative commenced during a World Health Organization workshop in 1999. The initial goals were (1) to propose a new allergic rhinitis classification, (2) to promote the concept of multi-morbidity in asthma and rhinitis and (3) to develop guidelines with all stakeholders that could be used globally for all countries and populations. ARIA-disseminated and implemented in over 70 countries globally-is now focusing on the implementation of emerging technologies for individualized and predictive medicine. MASK [MACVIA (Contre les Maladies Chroniques pour un Vieillissement Actif)-ARIA Sentinel NetworK] uses mobile technology to develop care pathways for the management of rhinitis and asthma by a multi-disciplinary group and by patients themselves. An app (Android and iOS) is available in 20 countries and 15 languages. It uses a visual analogue scale to assess symptom control and work productivity as well as a clinical decision support system. It is associated with an inter-operable tablet for physicians and other health care professionals. The scaling up strategy uses the recommendations of the European Innovation Partnership on Active and Healthy Ageing. The aim of the novel ARIA approach is to provide an active and healthy life to rhinitis sufferers, whatever their age, sex or socio-economic status, in order to reduce health and social inequalities incurred by the disease.

Community owned solutions for fire management in tropical ecosystems: case studies from Indigenous communities of South America.

Abstract: Fire plays an increasingly significant role in tropical forest and savanna ecosystems, contributing to greenhouse gas emissions and impacting on biodiversity. Emerging research shows the potential role of Indigenous land-use practices for controlling deforestation and reducing CO2 emissions. Analysis of satellite imagery suggests that Indigenous lands have the lowest incidence of wildfires, significantly contributing to maintaining carbon stocks and enhancing biodiversity. Yet acknowledgement of Indigenous peoples' role in fire management and control is limited, and in many cases dismissed, especially in policy-making circles. In this paper, we review existing data on Indigenous fire management and impact, focusing on examples from tropical forest and savanna ecosystems in Venezuela, Brazil and Guyana. We highlight how the complexities of community owned solutions for fire management are being lost as well as undermined by continued efforts on fire suppression and firefighting, and emerging approaches to incorporate Indigenous fire management into market- and incentive-based mechanisms for climate change mitigation. Our aim is to build a case for supporting Indigenous fire practices within all scales of decision-making by strengthening Indigenous knowledge systems to ensure more effective and sustainable fire management.This article is part of the themed issue 'The interaction of fire and mankind'.

Support for Augmented Reality Simulation Systems: The Effects of Scaffolding on Learning Outcomes and Behavior Patterns

Abstract: An AR-based simulation system that integrates background knowledge and experimental support (AR-SaBEr) was designed as a learning tool for teaching basic principles of electricity to ninth-grade students. The aim of this study was to investigate how supporting the learner focus on meaningful activities affects behavior and learning performance. The sample was 82 students, who were randomly assigned to two groups. The control group used AR-SaBEr with no support for recommending activities. The experimental group had personalized extra support designed to help learners focus on the subject matters that they did not master. The study found that learners from the experimental group showed better learning achievements than those who participated in the control group. Furthermore, learners’ behavioral patterns were dependent upon the support received. Learners from the control group were more willing to browse information about activities than to read about the subject before experimenting. Learners from the experimental group browsed information about prior to carrying them out and read about the subject matter prior to experimentation. The observed behavioral patterns and learning achievements suggest that in augmented reality based simulation environments, it is worth providing mechanisms to focus the attention of students on the most relevant topics for them.

Extending the geometric deformation: New black hole solutions

Abstract: By using the extension of the Minimal Geometric Deformation approach, recently developed to investigate the exterior spacetime of a self-gravitating system in the Braneworld, we identified a master solution for the deformation undergone by the radial metric component when time deformations are produced by bulk gravitons. A specific form for the temporal deformation is used to generate a new exterior solution with a tidal charge Q. The main feature of this solution is the presence of higher-order terms in the tidal charge, thus generalizing the well known tidally charged solution. The horizon of the black hole lies inside the Schwarzschild radius, h < rs = 2ℳ, indicating that extra-dimensional effects weaken the gravitational field.

Cytotoxicity and genotoxicity induced by coal and coal fly ash particles samples in V79 cells

Abstract: Exposure to coal and coal ashes can cause harmful effects in in vitro and in vivo systems, mainly by the induction of oxidative damage. The aim of this work was to assess cytotoxic and genotoxic effects using the V79 cell line treated with coal and coal fly ash particles derived from a coal power plant located in Santa Catarina, Brazil. Two coal samples (COAL11 and COAL16) and two coal fly ash samples (CFA11 and CFA16) were included in this study. COAL16 was co-firing with a mixture of fuel oil and diesel oil. The comet assay data showed that exposure of V79 cells to coal and coal fly ash particles induced primary DNA lesions. Application of lesion-specific endonucleases (FPG and ENDO III) demonstrated increased DNA effects indicating the presence of high amounts of oxidative DNA lesions. The cytokinesis-block micronucleus cytome assay analysis showed that exposure of V79 cells to high concentrations of coal and coal fly ash particles induced cytotoxic effects (apoptosis and necrosis) and chromosomal instability (nucleoplasmic bridges, nuclear buds, and micronucleus (MN) formation). These results may be associated with compounds contained in the surface of the particles as hazardous elements, ultrafine/nanoparticles, and polycyclic aromatic hydrocarbons (PAHs) which were detected in the samples. Graphical abstract ᅟ.

Scaling up strategies of the chronic respiratory disease programme of the European Innovation Partnership on Active and Healthy Ageing (Action Plan B3: Area 5)

Abstract: Action Plan B3 of the European Innovation Partnership on Active and Healthy Ageing (EIP on AHA) focuses on the integrated care of chronic diseases. Area 5 (Care Pathways) was initiated using chronic respiratory diseases as a model. The chronic respiratory disease action plan includes (1) AIRWAYS integrated care pathways (ICPs), (2) the joint initiative between the Reference site MACVIA-LR (Contre les MAladies Chroniques pour un VIeillissement Actif) and ARIA (Allergic Rhinitis and its Impact on Asthma), (3) Commitments for Action to the European Innovation Partnership on Active and Healthy Ageing and the AIRWAYS ICPs network. It is deployed in collaboration with the World Health Organization Global Alliance against Chronic Respiratory Diseases (GARD). The European Innovation Partnership on Active and Healthy Ageing has proposed a 5-step framework for developing an individual scaling up strategy: (1) what to scale up: (1-a) databases of good practices, (1-b) assessment of viability of the scaling up of good practices, (1-c) classification of good practices for local replication and (2) how to scale up: (2-a) facilitating partnerships for scaling up, (2-b) implementation of key success factors and lessons learnt, including emerging technologies for individualised and predictive medicine. This strategy has already been applied to the chronic respiratory disease action plan of the European Innovation Partnership on Active and Healthy Ageing.

High-Throughput Sequencing Reveals Circulating miRNAs as Potential Biomarkers of Kidney Damage in Patients with Systemic Lupus Erythematosus.

Abstract: Renal involvement is one of the most severe manifestations of systemic lupus erythematosus (SLE). Renal biopsy is the gold standard when it comes to knowing whether a patient has lupus nephritis, and the degree of renal disease present. However, the biopsy has various complications, bleeding being the most common. Therefore, the development of alternative, non-invasive diagnostic tests for kidney disease in patients with SLE is a priority. Micro RNAs (miRNAs) are differentially expressed in various tissues, and changes in their expression have been associated with several pathological processes. The aim of this study was to identify changes in the abundance of miRNAs in plasma samples from patients with lupus nephritis that could potentially allow the diagnosis of renal damage in SLE patients. This is an observational case-control cross-sectional study, in which we characterized the differential abundance profiles of miRNAs among patients with different degrees of lupus compared with SLE patients without renal involvement and healthy control individuals. We found 89 miRNAs with changes in their abundance between lupus nephritis patients and healthy controls, and 17 miRNAs that showed significant variations between SLE patients with or without renal involvement. Validation for qPCR of a group of miRNAs on additional samples from lupus patients with or without nephritis, and from healthy individuals, showed that five miRNAs presented an average detection sensitivity of 97%, a specificity of 70.3%, a positive predictive value of 82.5%, a negative predictive value of 96% and a diagnosis efficiency of 87.9%. These results strongly suggest that miR-221-5p, miR-380-3p, miR-556-5p, miR-758-3p and miR-3074-3p are potential diagnostic biomarkers of lupus nephritis in patients with SLE. The observed differential pattern of miRNA abundance may have functional implications in the pathophysiology of SLE renal damage.

Food Insecurity of Children and Shame of Others Knowing They Are Without Food

Abstract: We studied the association of shame when children experience food insecurity and management strategies. The cross-sectional study assessed food insecurity in 404 children using 2 instruments with 10 and 11 items for food insecurity and management strategies. Food insecurity in children was associated with shame of others knowing that they were out of food (γ = 0.37, P < .01). Nine out of 11 management strategies were associated (P < 0.05) with feeling of shame of being out of food. Older girls were most likely to report shame when they reported lack of food (P < .01). Understanding these relations may increase access to food in socially acceptable ways.

Automatic heart sound recording classification using a nested set of ensemble algorithms

Abstract: Automated phonocardiogram (PCG) analysis may provide better clinical information to physicians for analyzing and diagnosing different heart abnormalities. However, despite recent advances in PCG analysis methods, it is still a challenging task to extract accurate and useful information from contaminated heart sound recordings. The main objective of this paper is to introduce a new approach for classification of normal and abnormal heart sound recordings using a nested ensemble of algorithms that includes Random Forest, LogitBoost and a Cost-Sensitive Classifier. The approach consisted of three stages: preprocessing, classification and evaluation. In the preprocessing stage, PCG signals were first downsampled to 1 kHz using a polyphase antialiasing filter. Next, each heart sound was segmented using Springer's improved version of Schmidt's method to identify four states; S1, S2, systole and diastole. Thereafter, 131 features in time, frequency, wavelet and statistical domains were extracted from the entire signal and from the timings of the states. In the classification stage, the meta-classifier was cross validated on the entire training dataset provided by Physionet Challenge 2016. In the evaluation stage, the sensitivity and specificity of the trained algorithm was tested with unseen signals selected randomly by the Challenge testing environment. Experimental results showed that the proposed approach achieved an overall score of 84.48%, ranking 5th. The use of a nested set of ensemble classifier with a combined set of features extracted from different domains helped reduce overfitting and improved classification performance.

Colony geometry and structural complexity of the endangered species Acropora cervicornis partly explains the structure of their associated fish assemblage.

Abstract: In the past decade, significant efforts have been made to describe fish-habitat associations. However, most studies have oversimplified actual connections between fish assemblages and their habitats by using univariate correlations. The purpose of this study was to identify the features of habitat forming corals that facilitate and influences assemblages of associated species such as fishes. For this we developed three-dimensional models of colonies of Acropora cervicornis to estimate geometry (length and height), structural complexity (i.e., volume, density of branches, etc.) and biological features of the colonies (i.e., live coral tissue, algae). We then correlated these colony characteristics with the associated fish assemblage using multivariate analyses. We found that geometry and complexity were better predictors of the structure of fish community, compared to other variables such as percentage of live coral tissue or algae. Combined, the geometry of each colony explained 40% of the variability of the fish assemblage structure associated with this coral species; 61% of the abundance and 69% of fish richness, respectively. Our study shows that three-dimensional reconstructions of discrete colonies of Acropora cervicornis provides a useful description of the colonial structural complexity and may explain a great deal of the variance in the structure of the associated coral reef fish community. This demonstration of the strongly trait-dependent ecosystem role of this threatened species has important implications for restoration and conservation efforts.

Food insecurity reported by children but not by mothers is associated with lower quality of diet and shifts in foods consumed.

Abstract: Household food security shows little indication of nutrient inadequacy among children according to reports made by parents. We examined the associations of food insecurity as reported by children and mothers with childrens consumption of energy macronutrients such as vitamin A calcium iron and zinc and selected foods and whether these associations differed by childs gender. This cross-sectional study had non-probabilistic 128 Venezuelan mother-child pairs. We assessed food insecurity and management strategies in children using 10- and nine-item instruments respectively. Mothers report of food insecurity came from a previously validated 12-item instrument. Nutrient intake of children was assessed with a 67-item food frequency questionnaire. Comparisons were made using chi-square test for contingency tables and t-tests for trends (P<0.05). Linear regression models were used for intakes of nutrients and selected foods. We tested for interactions with gender. Prevalence of child- and mother-reported food insecurity was 83.6 and 61.7% respectively (P <0.01). Greater food insecurity or management strategies reported by boys was associated with lower calcium iron and zinc intake (P <0.05) but reported intakes were low in girls who are even food secure. Rice and corn flour consumption was higher with higher food insecurity in children. Papaya and banana were less consumed by food-insecure children. We found shifts in 13 of 67 foods consumed with less quality in those food insecure as reported by children. Mother-reported food insecurity was associated only with rice intake of children. In contrast to mothers reports food insecurity reported by children was associated with childrens lower quality of diet and shifts in foods consumed.

Application of computational fluid dynamics and surrogate-coupled evolutionary computing to enhance centrifugal-pump performance

Abstract: To reduce the total design and optimization time, numerical analysis with surrogate-based approaches is being used in turbomachinery optimization. In this work, multiple surrogates are coupled with an evolutionary genetic algorithm to find the Pareto optimal fronts (PoFs) of two centrifugal pumps with different specifications in order to enhance their performance. The two pumps were used a centrifugal pump commonly used in industry (Case I) and an electrical submersible pump used in the petroleum industry (Case II). The objectives are to enhance head and efficiency of the pumps at specific flow rates. Surrogates such as response surface approximation (RSA), Kriging (KRG), neural networks and weighted-average surrogates (WASs) were used to determine the PoFs. To obtain the objective functions’ values and to understand the flow physics, Reynolds-averaged Navier–Stokes equations were solved. It is found that the WAS performs better for both the objectives than any other individual surrogate. The best...

From Chávez to Maduro: Continuity and Change in Venezuelan Foreign Policy

Abstract: This article addresses the transition from the presidency of Hugo Chavez to that of Nicolas Maduro, in the light of the effects of the dynamics in domestic politics and the changing international order on the formulation of Venezuela's foreign policy. We start from a central question: how does Maduro's government, amid a less favourable global scenario, face the international commitments made by its predecessor under complex and different domestic conditions? Our central hypothesis is that the historical currents of sociopolitical fragmentation, regional tensions and the energy market, pose difficulties to the continuation of an expansive foreign policy, but in turn act as a stimulus for greater centralisation of power internally, and the politicisation of the foreign policy agenda, in line with the objectives and general trends pursued by the governing party.

Modeling dynamic recovery strategy for composite web services execution

Abstract: During the execution of Composite Web Services (CWS), a component Web Service (WS) can fail and can be repaired with strategies such WS retry, substitution, compensation, roll-back, replication, or checkpointing. Each strategy behaves differently on different scenarios, impacting the CWS QoS. We propose a non intrusive dynamic fault tolerant model that analyses several levels of information: environment state, execution state, and QoS criteria, to dynamically decide the best recovery strategy when a failure occurs. We present an experimental study to evaluate the model and determine the impact on QoS parameters of different recovery strategies; and evaluate the intrusiveness of our strategy during the normal execution of CWSs.

The Venezuelan prison: from neoliberalism to the Bolivarian revolution

Abstract: This paper aims to give an account of the main changes in the Venezuelan prison system in the last three decades. This period extends from the years of neoliberal hegemony to the period of the Bolivarian revolution, characterized by a strong commitment to redistributive policies, economic regulation and social inclusion strategies. We point out that while the Bolivarian government has adopted a social welfare model, it has continued to rely upon punitive policies that are most often associated with neoliberal governments. We map out this contradiction and discuss the impacts the current government’s penal policies have had on social relations within the prison system. Using ethnographic data we sketch out the social organization and distribution of power that develops when the state loses control of the prison. We show that prisons in Venezuela do not adhere to a disciplinary model, whereby prisoners must submit to an external administration’s intensive surveillance and control. Instead, what has developed is a form of internal governance administered by prisoners themselves.

Bacterias causantes de enfermedades transmitidas por alimentos: una mirada en colombia

Abstract: Objetivo: Las enfermedades de transmision alimentaria constituyen un grave problema de salud publica a nivel mundial; entre sus causas mas frecuentes se encuentran los patogenos bacterianos, los cuales generan desde sintomas gastrointestinales hasta complicaciones que pueden conducir a la muerte. En esta revision se describen estudios sobre deteccion de patogenos bacterianos en diferentes alimentos en Colombia publicados entre 2010 y 2013, y se presenta informacion acerca de las caracteristicas y prevalencia de los microorganismos encontrados, alimentos implicados y caracterizacion de los aislados. La busqueda en bases de datos arrojo un total de 16 articulos enfocados directamente a la deteccion de cinco patogenos: Salmonella spp., Listeria monocytogenes, Escherichia coli, Aeromonas spp. y Vibrio spp. La mayor parte de los estudios correspondio al genero Salmonella. No se hallaron investigaciones relacionadas con otras bacterias causantes de enfermedades de transmision alimentaria. Los productos analizados fueron principalmente de origen animal, desde alimentos crudos, como pescado y carnes, hasta alimentos listos para el consumo. Esta revision evidencia que a pesar de la importancia a nivel de salud publica de detectar y caracterizar bacterias patogenas trasmitidas por alimentos existen muy pocos estudios publicados relacionados con esta tematica en el periodo revisado. Asimismo, los trabajos se encaminaron primordialmente a la busqueda del microorganismo en el producto final y no a lo largo de la cadena productiva.

Electrochemical oxygen transfer reactions: electrode materials, surface processes, kinetic models, linear free energy correlations, and perspectives

Abstract: This work summarizes progresses achieved in electrochemical oxygen transfer reactions from water to organic pollutant molecules on metal oxide electrodes during the past two decades. Fundamental understanding of the dynamics of the electrochemical oxygen transfer reaction is of crucial importance for the development of key concepts of electrocatalytic processes, leading to the implementation of environmental electrochemistry wastewater treatment schemes with rational design of the suitable electrocatalytic systems. We discuss the current knowledge on the electrochemical oxygen transfer reaction, emphasizing the importance of surface processes in order to generalize mechanistically the experimental results obtained on different electrode materials, describing also the practical kinetic models developed and their implications. From the information gathered in this review, it is apparent that explanations for the kinetics of the reactions in relation to the structure of the organic compounds involved is lacking, hence that new information about structure-reactivity relationships is needed. We show in particular that the open circuit decay of the concentration of radical cations, obtained from spectroelectrochemical data, allows correlating the structure of adsorbed states with reactivity during oxygen transfer reactions, pointing as well to research efforts required to understand the catalytic performance of metal oxide electrodes in decomposing organic compounds strongly adsorbed on their surfaces. Finally, some perspectives for future research in this area are briefly commented.

The influence of small amounts of linear polycaprolactone chains on the crystallization of cyclic analogue molecules

Abstract: Cyclic poly(e-caprolactone) model chains (C-PCL) were synthesized by a ring closure click chemistry technique. Identical linear precursors (L-PCL) of equivalent molecular lengths were also prepared. The effect of adding small amounts of linear (L-PCL) to cyclic analogs (C-PCL) was studied by preparing blends (C/L) in solution of the following composition range: 95/5, 90/10 and 80/20. Two sets of blends with PCL samples of different number average molecular weights (3 and 12 kg mol−1) were studied. The blends were analyzed by polarized light optical microscopy (PLOM) and advanced Differential Scanning Calorimetry (DSC) techniques that included non-isothermal and isothermal crystallization studies and thermal fractionation by SSA (Successive Self-nucleation and Annealing). The results show that addition of small amounts of linear chains (i.e., 5 and 10 wt%) to cyclic PCLs produces synergistic decreases in crystallization and melting temperatures, crystallinity degrees and isothermal crystallization rates (for both 3 and 12 kg mol−1 samples). When the amount of linear chains reaches 20 wt%, a significant recovery of a simple mixing law behavior is obtained. Thermal fractionation demonstrated that the addition of linear chains can reduce the annealing capacity of cyclic chains. The behavior of the C/L blends can be explained by the threading of ring molecules by linear chains. This threading effect amounts to an increase in entanglement density that reduces chain diffusion and hence crystallization rate.

Are we overestimating the niche? Removing marginal localities helps ecological niche models detect environmental barriers

Abstract: Correlative ecological niche models (ENMs) estimate species niches using occurrence records and environmental data. These tools are valuable to the field of biogeography, where they are commonly used to infer potential connectivity among populations. However, a recent study showed that when locally relevant environmental data are not available, records from patches of suitable habitat protruding into otherwise unsuitable regions (e.g., gallery forests within dry areas) can lead to overestimations of species niches and their potential distributions. Here, we test whether this issue obfuscates detection of an obvious environmental barrier existing in northern Venezuela – that of the hot and xeric lowlands separating the Peninsula de Paraguana from mainland South America. These conditions most likely promote isolation between mainland and peninsular populations of three rodent lineages occurring in mesic habitat in this region. For each lineage, we calibrated optimally parameterized ENMs using mainland records only, and leveraged existing habitat descriptions to assess whether those assigned low suitability values corresponded to instances where the species was collected within locally mesic conditions amidst otherwise hot dry areas. When this was the case, we built an additional model excluding these records. We projected both models onto the peninsula and assessed whether they differed in their ability to detect the environmental barrier. For the two lineages in which we detected such problematic records, only the models built excluding them detected the barrier, while providing additional insights regarding peninsular populations. Overall, the study reveals how a simple procedure like the one applied here can deal with records problematic for ENMs, leading to better predictions regarding the potential effects of the environment on lineage divergence.

Interplay between poly(ethylene oxide) and poly(L-lactide) blocks during diblock copolymer crystallization

Abstract: The influence of composition and crystallization conditions on the behavior of double crystalline poly (ethylene oxide-b-L-lactide) (PEO-b-PLLA) diblock copolymers is investigated. Poly(L-lactide) contents in the synthesized copolymers vary from 50 to 91%, and the molecular weight of the PLLA block ranges from 2 to 20 kg mol−1, while that of the PEO block is kept constant at 2 kg mol−1. In bulk samples, DSC results show a synergistic interaction between the crystallization processes of the two blocks. The PEO block provides heterogeneities and exerts a plasticizing action which favors the crystallization of the PLLA block with a nucleation efficiency of 30%. In contrast, the subsequent crystallization of the PEO block is subject to two opposing effects: (a) the nucleating action of PLLA crystals and (b) the topological and geometrical constraints imposed by PLLA crystals, especially when the PEO content is 20 wt% or less. In the case of ultra thin films, block copolymers with PEO contents equal or smaller than 20 wt% form distorted PLLA single crystals when crystallized from the melt. However, upon increasing the PEO content in the system to 33 wt% (by blending or copolymerization), the distortions disappear and the angle between the {110} growth faces changes from 140° to 121°, since the PEO block acts as a solvent or plasticizer for the PLLA block during the crystallization process. PEO incorporation can therefore tailor the rate and morphology of PLLA block crystallization. TEM and AFM studies allowed direct observation of the PEO block dendritic crystals on the surface of lozenge-shaped PLLA crystals previously formed during cooling from the melt.

A novel detector assembly for detecting thermal neutrons, fast neutrons and gamma rays

Abstract: A new composite detector has been developed by combining two different commercial scintillators. The device has the capability to detect gamma rays as well as thermal and fast neutrons; the signal discrimination between the three types is performed on-line by means of waveform digitizers and PSD algorithms. This work describes the assembled detector and its discrimination performance to be employed in the applied field.