Dynamics of equatorial mass-flow adjustment

June 1979.Includes bibliographical references.Sponsored by the Global Atmospheric Research Program, Climate Dyanmics Research Section, National Science Foundation ATM76-09370.Sponsored by the Global Atmospheric Research Program, Climate Dyanmics Research Section, National Science Foundation ATM78-08125

Geostrophic adjustment in an axisymmetric vortex

November 1979.Includes bibliographical references.Supported by Global Atmospheric Research Program, National Science Foundation, and the GATE Project Office, NOAA ATM-7808125

Recruiting strategic human capital from MNCs-Does hiring MNC managers enable exporting in domestic firms?

Exporting is a central growth strategy for most firms and managers with international experience are instrumental for export decisions. We suggest that such managers can be hired from Multinational Corporations (MNCs). We integrate theory from strategic human capital research into models explaining export decisions. We theorize that hiring managers from MNCs increases the odds of domestic firms to start exporting and this effect depends on the similarities between hiring firms and MNCs. We hypothesize that young firms will benefit comparatively less from hiring MNC managers. In contrast, firms with internationally diverse workforces and with high degrees of hierarchical specialization will benefit the most from hiring MNC managers. We test and support these hypotheses for 474,926 domestic firms in Sweden, which we observe between 2007 and 2015

Major role of iron uptake systems in the intrinsic extra-intestinal virulence of the genus Escherichia revealed by a genome-wide association study

The genus Escherichia is composed of several species and cryptic clades, including E. coli, which behaves as a vertebrate gut commensal, but also as an opportunistic pathogen involved in both diarrheic and extra-intestinal diseases. To characterize the genetic determinants of extra-intestinal virulence within the genus, we carried out an unbiased genome-wide association study (GWAS) on 370 commensal, pathogenic and environmental strains representative of the Escherichia genus phylogenetic diversity and including E. albertii (n = 7), E. fergusonii (n = 5), Escherichia clades (n = 32) and E. coli (n = 326), tested in a mouse model of sepsis. We found that the presence of the high-pathogenicity island (HPI), a similar to 35 kbp gene island encoding the yersiniabactin siderophore, is highly associated with death in mice, surpassing other associated genetic factors also related to iron uptake, such as the aerobactin and the sitABCD operons. We confirmed the association in vivo by deleting key genes of the HPI in E. coli strains in two phylogenetic backgrounds. We then searched for correlations between virulence, iron capture systems and in vitro growth in a subset of E. coli strains (N = 186) previously phenotyped across growth conditions, including antibiotics and other chemical and physical stressors. We found that virulence and iron capture systems are positively correlated with growth in the presence of numerous antibiotics, probably due to co-selection of virulence and resistance. We also found negative correlations between virulence, iron uptake systems and growth in the presence of specific antibiotics (i.e. cefsulodin and tobramycin), which hints at potential "collateral sensitivities" associated with intrinsic virulence. This study points to the major role of iron capture systems in the extra-intestinal virulence of the genus Escherichia. Author summary Bacterial isolates belonging to the genus Escherichia can be human commensals but also opportunistic pathogens, with the ability to cause extra-intestinal infection. There is therefore the need to identify the genetic elements that favour extra-intestinal virulence, so that virulent bacterial isolates can be identified through genome analysis and potential treatment strategies be developed. To reduce the influence of host variability on virulence, we have used a mouse model of sepsis to characterize the virulence of 370 strains belonging to the genus Escherichia, for which whole genome sequences were also available. We have used a statistical approach called Genome-Wide Association Study (GWAS) to show how the presence of genes that encode for iron scavenging are significantly associated with the propensity of a bacterial isolate to cause extra-intestinal infections. Taking advantage of previously generated growth data on a subset of the strains and its correlation to virulence we generated hypothesis on the relationship between iron scavenging and growth in the presence of various antimicrobials, which could have implications for developing new treatment strategies

High performance of symmetric micro supercapacitors based on silicon nanowires using N-methyl-N-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide as electrolyte

This work describes the development and performance of a symmetric microsupercapacitor made of nanostructured electrodes based on silicon nanowires (SiNWs) deposited using chemical vapor deposition (CVD) on silicon substrates. The performance of the SiNWs micro-supercapacitor employing an aprotic ionic liquid (N-methyl-N-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide) (PYR13TFSI) as an electrolyte was able to deliver a maximal power density of 182 mW cm-2 and a specific energy of 190 µJ cm-2 operating at a wide cell voltage of 4V with a quasi-ideal capacitive behaviour. The lifetime of the device exhibited a remarkable electrochemical stability retaining 75 % of the initial capacitance after several million galvanostatic charge-discharge cycles at a high current density of 1 mA cm-2. Furthermore, a coulombic efficiency of approximately 99 % was obtained after galvanostatic cycling test without structural degradation on the morphology of SiNWs

Desarrollo del modelo aerodinámico de un cohete supersónico

Este trabajo presenta el diseño aerodinámico del cohete Theros III, que participó en la competencia Spaceport America Cup. Las estructuras aerodinámicas fueron diseñadas en base a información de la literatura y corregidas con datos del simulador OpenRocket en un proceso iterativo que incluyó el diseño y selección del motor del lanzador. La telemetría obtenida en vuelo permitió concluir que las estimaciones del coeficiente de arrastre del lanzador, realizadas con OpenRocket empleando el método de Barrowman, fueron en exceso. La implementación de un modelo de mecánica de fluidos computacional permitió obtener coeficientes de arrastre menores a los previstos por OpenRocket y similares a los estimados por Aerolab, simulador que emplea datos experimentales para sus predicciones.Facultad de Ingenierí

SiNWs-based electrochemical double layer micro-supercapacitors with wide voltage window (4V) and long cycling stability using a protic ionic liquid electrolyte

The present work reports the use and application of a novel protic ionic liquid (triethylammonium bis(tri fluoromethylsulfonyl)imide; NEtH TFSI) as an electrolyte for symmetric planar micro-supercapacitors based on silicon nanowire electrodes. The excellent performance of the device has been successfully demonstrated using cyclic voltammetry, galvanostatic charge-discharge cycles and electrochemical impedance spectroscopy. The electrochemical characterization of this system exhibits a wide operative voltage of 4 V as well as an outstanding long cycling stability after millions of galvanostatic cycles at a high current density of 2 mA cm. In addition, the electrochemical double layer micro-supercapacitor was able to deliver a high power density of 4 mWcm in a very short time pulses (a few ms). Our results could be of interest to develop prospective on-chip micro-supercapacitors using protic ionic liquids as electrolytes with high performance in terms of power and energy densities