Material design of elastic structures using Voronoi cells

New tools for the design of metamaterials with periodic microarchitectures are presented. Initially, a two‐scale material design approach is adopted. At the structure scale, the material effective properties and their spatial distribution are obtained through a Free Material Optimization technique. At the microstructure scale, the material microarchitecture is designed by appealing to a Topology Optimization Problem (TOP). The TOP is based on the topological derivative and the level set function. The new proposed tools are used to facilitate the search of the optimal microarchitecture configuration. They consist of the following: (i) a procedure to choose an adequate shape of the unit cell domain where the TOP is formulated and shapes of Voronoi cells associated with Bravais lattices are adopted and (ii) a procedure to choose an initial material distribution within the Voronoi cell being utilized as the initial configuration for the iterative TOP

Material design of elastic structures using Voronoi cells

This is the peer reviewed version of the following article: [Podestá JM, Méndez CG, Toro S, Huespe AE, Oliver J. Material design of elastic structures using Voronoi cells. Int J Numer Methods Eng. 2018;115:269–292. https://doi.org/10.1002/nme.5804], which has been published in final form at https://doi.org/10.1002/nme.5804. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-ArchivingNew tools for the design of metamaterials with periodic microarchitectures are presented. Initially, a two-scale material design approach is adopted. At the structure scale, the material effective properties and their spatial distribution are obtained through a Free Material Optimization technique. At the microstructure scale, the material microarchitecture is designed by appealing to a Topology Optimization Problem (TOP). The TOP is based on the topological derivative and the level set function. The new proposed tools are used to facilitate the search of the optimal microarchitecture configuration. They consist of the following: (i) a procedure to choose an adequate shape of the unit cell domain where the TOP is formulated and shapes of Voronoi cells associated with Bravais lattices are adopted and (ii) a procedure to choose an initial material distribution within the Voronoi cell being utilized as the initial configuration for the iterative TOP.Peer ReviewedPostprint (author's final draft

Dissemination of blaIMP-8 among Enterobacteriaceae isolates from a Buenos Aires Hospital

Entre agosto de 2008 y diciembre de 2011 se detectaron en el Hospital Interzonal General de Agudos «Evita» de Lanús 6 aislamientos de enterobacterias productoras de metalo- β-lactamasas, distribuidos en tres especies: Enterobacter cloacae (4), Klebsiella oxytoca (1) y Citrobacter freundii (1). Los seis aislamientos presentaron un perfi l de multirresistencia y se confi rmó la presencia del gen blaIMP-8. Cinco aislamientos además expresaron la β-lactamasa de espectro extendido PER-2. El gen blaIMP-8 fue hallado como primer casete de un integrón de clase 1. Sin embargo, la secuencia 3´ conservada no pudo detectarse en tres aislamientos. En todos los casos, el gen blaIMP-8 fue transferido por conjugación a Escherichia coli resistente a azida. Mediante PFGE se observó que los cuatro aislamientos de E. cloacae no estuvieron genéticamente relacionados. Estos son los primeros hallazgos de metalo-β-lactamasas en la institución, que sugieren una posible diseminación horizontal del gen blaIMP-8 intra e interespecies.From August 2008 to December 2011, six metallo-β-lactamase-producing isolates, four Enterobacter cloacae, one Klebsiella oxytoca and one Citrobacter freundii, were detected at Hospital Interzonal General de Agudos “Evita” in Lanús. All six isolates showed multiresistant profi les and the presence of the blaIMP-8 gene. Five isolates also expressed PER-2 extended spectrum β-lactamase. The blaIMP-8 gene was found as the fi rst cassette in a class 1 integron. However, the 3´ conserved sequence could not be detected in three isolates. In all cases, blaIMP-8 was transferred by conjugation to azide-resistant Escherichia coli J53. PFGE analysis revealed that the four E. cloacae isolates were not genetically related. These are the fi rst metallo-β-lactamases detected in this institution and our results suggest a possible intra- and inter-species horizontal dissemination of blaIMP-8.Fil: Togneri, Ana M.. Hospital Interzonal General de Agudos Evita. Laboratorio de Bacteriología; ArgentinaFil: Gómez, Sonia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Area de Antimicrobianos; ArgentinaFil: Podestá, Laura B.. Hospital Interzonal General de Agudos Evita. Laboratorio de Bacteriología; ArgentinaFil: Pérez, Marcela P.. Hospital Interzonal General de Agudos Evita. Laboratorio de Bacteriología; ArgentinaFil: Faccone, Diego Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Area de Antimicrobianos; ArgentinaFil: Ríos, Lidia E.. Hospital Interzonal General de Agudos Evita. Laboratorio de Bacteriología; ArgentinaFil: Gañete, Marcelo A.. Hospital Interzonal General de Agudos Evita. Laboratorio de Bacteriología; ArgentinaFil: Anchordoqui, María S. . Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Area de Antimicrobianos; ArgentinaFil: Pasterán, Fernando G.. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Area de Antimicrobianos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Corso, Alejandra C.. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Area de Antimicrobianos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Valoración nutricional del paciente con obesidad mórbida

La incidencia de la obesidad sigue creciendo, a nivel mundial, a una velocidad alarmante.Argentina se encuentra en el 13º lugar entre los países más gordos del mundo, en el 2º lugar de América,  con el  60% de prevalencia de sobrepeso, prácticamente igual a la de la mayor parte del mundo.Los cambios en el estilo de vida de las sociedades postindustriales nos han convertido en sociedades obesogénicas. A  su vez, la globalización marcada desde las últimas décadas del siglo XX, hace que se produzca una nivelación del estilo de vida. A este proceso se lo denomina “transición nutricional” y se caracteriza por marcado sedentarismo, elevado consumo de alimentos ricos en grasas, sobre todo saturadas, sal, azúcar y disminución de las fibras y micronutrientes, conduciendo al consumo de dietas desequilibradas, con incremento de la ingesta de macronutrientes, pero marginalmente deficientes en minerales y vitaminas

Valoración nutricional del paciente con obesidad mórbida

El obeso mórbido no es un paciente bien nutrido. Aunque tiene depósitos excesivos de energía en forma de grasa, puede tener carencias nutritivas clínicas o subclínicas por seguir dietas desequilibradas o demasiado restrictivas durante períodos prolongados de tiempo. Este es un estudio descriptivo transversal no experimental, de carácter multicéntrico. Se estudió a 158 pacientes con diagnóstico clínico de Obesidad Mórbida de la provincia de Mendoza, Buenos Aires y Salta. Se realizó una valoración nutricional mediante una encuesta de hábitos alimentarios, determinaciones antropométricas y bioquímicas de vitaminas. El 83% de los pacientes presentó algún tipo de deficiencia. El 40% tenían déficit de vitamina B1, el 1,9% de B12 y el 3,2% de ácido fólico. La deficiencia más marcada fue la de vitamina D, que fue del 82,2 %. Se relacionó este último déficit con diferentes variables. Se observó una leve relación inversa entre las variables IMC y vitamina D, lo que señala que a medida que el IMC aumenta, las concentraciones de vitamina D disminuyen. Además, se puede afirmar que existe una leve relación inversa entre las variables “diámetro sagital” y “diámetro de cintura” con las concentraciones séricas de vitamina D. A medida que el diámetro sagital y de la cintura aumenta, las concentraciones de vitamina D disminuyen. Con respecto a los minerales, se hallaron concentraciones bajas de calcio iónico en el 25,4% de los pacientes, de magnesio en el 6,1%, de fósforo en el 2,8% y de zinc solo en el 0,7%. La absorción, distribución, metabolismo y/o excreción de nutrientes podrían estar alterados en la obesidad, tanto como su biodisponibilidad. Es necesario medir micronutrientes en toda evaluación clínico-nutricional del paciente con obesidad mórbida. Se necesitan estudios locales para determinar prevalencia, mecanismos, consecuencias y cómo prevenir las deficiencias en la población obes

Meeting reports: Research on Coupled Human and Natural Systems (CHANS): Approach, Challenges, and Strategies

Understanding the complexity of human–nature interactions is central to the quest for both human well-being and global sustainability. To build an understanding of these interactions, scientists, planners, resource managers, policymakers, and communities increasingly are collaborating across wide-ranging disciplines and knowledge domains. Scientists and others are generating new integrated knowledge on top of their requisite specialized knowledge to understand complex systems in order to solve pressing environmental and social problems (e.g., Carpenter et al. 2009). One approach to this sort of integration, bringing together detailed knowledge of various disciplines (e.g., social, economic, biological, and geophysical), has become known as the study of Coupled Human and Natural Systems, or CHANS (Liu et al. 2007a, b). In 2007 a formal standing program in Dynamics of Coupled Natural and Human Systems was created by the U.S. National Science Foundation. Recently, the program supported the launch of an International Network of Research on Coupled Human and Natural Systems (CHANS-Net.org). A major kick-off event of the network was a symposium on Complexity in Human–Nature Interactions across Landscapes, which brought together leading CHANS scientists at the 2009 meeting of the U.S. Regional Association of the International Association for Landscape Ecology in Snowbird, Utah. The symposium highlighted original and innovative research emphasizing reciprocal interactions between human and natural systems at multiple spatial, temporal, and organizational scales. The presentations can be found at ‹http://chans- net.org/Symposium_2009.aspx›. The symposium was accompanied by a workshop on Challenges and Opportunities in CHANS Research. This article provides an overview of the CHANS approach, outlines the primary challenges facing the CHANS research community, and discusses potential strategies to meet these challenges, based upon the presentations and discussions among participants at the Snowbird meeting

“Deficiencia de vitaminas en pacientes con obesidad mórbida”

El obeso mórbido no es un paciente bien nutrido. Aunque tiene depósitos excesivos de energía en forma de grasa, puede tener carencias nutritivas clínicas o subclínicas por seguir dietas desequilibradas o demasiado restrictivas durante períodos prolongados de tiempo

Evaluating Nuclei Concentration in Amyloid Fibrillation Reactions Using Back-Calculation Approach

Background: In spite of our extensive knowledge of the more than 20 proteins associated with different amyloid diseases, we do not know how amyloid toxicity occurs or how to block its action. Recent contradictory reports suggest that the fibrils and/or the oligomer precursors cause toxicity. An estimate of their temporal concentration may broaden understanding of the amyloid aggregation process. Methodology/Principal Findings: Assuming that conversion of folded protein to fibril is initiated by a nucleation event, we back-calculate the distribution of nuclei concentration. The temporal in vitro concentration of nuclei for the model hormone, recombinant human insulin, is estimated to be in the picomolar range. This is a conservative estimate since the back-calculation method is likely to overestimate the nuclei concentration because it does not take into consideration fibril fragmentation, which would lower the amount of nuclei Conclusions: Because of their propensity to form aggregates (non-ordered) and fibrils (ordered), this very low concentration could explain the difficulty in isolating and blocking oligomers or nuclei toxicity and the long onset time for amyloid diseases

Hormone-Dependent Expression of a Steroidogenic Acute Regulatory Protein Natural Antisense Transcript in MA-10 Mouse Tumor Leydig Cells

Cholesterol transport is essential for many physiological processes, including steroidogenesis. In steroidogenic cells hormone-induced cholesterol transport is controlled by a protein complex that includes steroidogenic acute regulatory protein (StAR). Star is expressed as 3.5-, 2.8-, and 1.6-kb transcripts that differ only in their 3′-untranslated regions. Because these transcripts share the same promoter, mRNA stability may be involved in their differential regulation and expression. Recently, the identification of natural antisense transcripts (NATs) has added another level of regulation to eukaryotic gene expression. Here we identified a new NAT that is complementary to the spliced Star mRNA sequence. Using 5′ and 3′ RACE, strand-specific RT-PCR, and ribonuclease protection assays, we demonstrated that Star NAT is expressed in MA-10 Leydig cells and steroidogenic murine tissues. Furthermore, we established that human chorionic gonadotropin stimulates Star NAT expression via cAMP. Our results show that sense-antisense Star RNAs may be coordinately regulated since they are co-expressed in MA-10 cells. Overexpression of Star NAT had a differential effect on the expression of the different Star sense transcripts following cAMP stimulation. Meanwhile, the levels of StAR protein and progesterone production were downregulated in the presence of Star NAT. Our data identify antisense transcription as an additional mechanism involved in the regulation of steroid biosynthesis