635 research outputs found

    Inversiones chinas en el transporte ferroviario: la rehabilitación del FFCC Blegrano Cargas como eje logístico para el desarrollo y crecimiento del comercio interno y externo

    Get PDF
    A lo largo de este trabajo de tesis desarrollaremos la conveniencia de China como socio estratégico para la rehabilitación del Ferrocarril Belgrano Cargas. Teniendo en cuenta el análisis de los factores que influyeron en la desinversión del sistema ferroviario argentino y describiendo los planes del Gobierno en concepto de transporte ferroviario. Luego se elaborará un análisis comparativo, en forma cualitativa y cuantitativa, del transporte por FFCC vs. el transporte automotor de carga. También, identificaremos las ventajas competitivas del FFCC Belgrano Cargas. Por último analizaremos la motivación del Gobierno Chino y sus compañías en invertir en proyectos de esta índole, y fundamentalmente en nuestro país

    Fabrication of high-resolution strain sensors based on wafer-level vacuum packaged MEMS resonators

    Get PDF
    The paper reports on the fabrication and characterization of high-resolution strain sensors for structural materials based on Silicon On Insulator flexural resonators manufactured by polysilicon Low-Pressure Chemical Vapour Deposition vacuum packaging. The sensors present sensitivity of 164 Hz/με and strain resolution limit of 150 pε on steel for a measurement time of 315 ms, in both tensile and compressive strain regimes. The readout of the sensor is implemented with a transimpedance oscillator circuit implemented on Printed Circuit Board, in which a microcontroller-based reciprocal frequency counter is integrated. The performance of the sensors on steel are investigated for measurement bandwidths from 1.5 to 500 Hz and a comparison with conventional metal strain gauges is proposed.The contribution of Mr. Filippo Bonafè, Mr. Fabrizio Tamarri, Mr. Michele Sanmartin and Mr. Giulio Pizzochero in the clean room processing employed for the manufacturing of the MEMS sensors is acknowledged. The contribution of Dr. Michele Bellettato in sample preparation is also acknowledged.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.sna.2016.01.00

    Strain sensing on steel surfaces using vacuum packaged MEMS resonators

    Get PDF
    The paper presents a technology for strain sensing on steel using resonant MEMS packaged in vacuum. For this purpose, a custom sensor fabrication technology and a novel vacuum packaging technique have been developed. The MEMS sensors have been fabricated by surface micromachining of thick (15 μm) Silicon On Insulator substrates with heavily doped handle layers View the MathML source(ρ = 0.005 Ωcm). Using this process, Double-Ended Tuning Fork (DETF) parallel-plate resonators with reduced coupling gaps (less than 1 μm) have been fabricated, using a high-performance Deep Reactive Ion Etching performed on submicrometer features realized by near-UV lithography combined with a maskless line narrowing technique. The devices have been bonded to a thin steel bar by epoxy glue, packaged in vacuum and tested by applying strain to the bar, showing good tolerances to packaging parasitics, measurement reversibility, and strain sensitivity of View the MathML source10Hz/με

    The influence of gender and social attention to gender equality on applicant acceptance into venture development programs: competing perspectives

    Get PDF
    Purpose – The purpose of this paper is to add to the small but growing body of research examining the influence of founder gender on new venture access to venture development programs. Design/methodology/approach – Hypotheses were tested utilizing a sample of 482 nascent technology ventures which applied for admittance into a venture development organization headquartered in the southern region of the United States from March 2004 through February 2016. Findings – Findings suggest that female-founded applicant ventures experience a higher likelihood of acceptance into venture development programs than male-founded applicant ventures. Results further suggest that social attention to gender equality reduces this effect for female-founded applicant ventures. Findings extend the understanding of the gendered nature of high-technology venturing and venture development organizations. Research limitations/implications – The findings of this study may not generalize to new ventures operating in other contexts (e.g., non-U.S., low-tech, and other venture development programs). Additionally, this study's design and data limitations do not allow for the establishment of causality or address founder motivations to apply for acceptance into venture development programs. Originality/value – This study adds to empirical findings regarding the influence of founder gender on new venture acceptance into venture development programs by developing and testing competing hypotheses. This study also extends extant research by examining the moderating effect of social attention to gender equality on the hypothesized relationships between founder gender and acceptance into venture development programs

    High-resolution strain sensing on steel by Silicon-On-Insulator flexural resonators fabricated with chip-level vacuum packaging

    No full text
    This paper reports on the fabrication and characterization of high-resolution strain sensors for steel based on Silicon On Insulator flexural resonators manufactured with chip-level LPCVD vacuum packaging. The sensors present high sensitivity (120 Hz/??), very high resolution (4 n?), low drift, and near-perfect reversibility in bending tests performed in both tensile and compressive strain regimes

    Fabrication and testing of a high resolution extensometer based on resonant MEMS strain sensors

    No full text
    A novel type of linear extensometer with exceptionally high resolution of 4 nm based on MEMS resonant strain sensors bonded on steel and operating in a vacuum package is presented. The tool is implemented by means of a steel thin bar that can be pre-stressed in tension within two fixing anchors. The extension of the bar is detected by using two vacuum-packaged resonant MEMS double-ended tuning fork (DETF) sensors bonded on the bar with epoxy glue, one of which is utilized for temperature compensation. Both sensors are driven by a closed loop self-oscillating transresistance amplifier feedback scheme implemented on a PCB (Printed Circuit Board). On the same board, a microcontroller-based frequency measurement circuit is also implemented, which is able to count the square wave fronts of the MEMS oscillator output with a resolution of 20 nsec. The system provides a frequency noise of 0.2 Hz corresponding to an extension resolution of 4 nm for the extensometer. Nearly perfect temperature compensation of the frequency output is achieved in the temperature range 20-35°C using the reference sensor

    Interaction of Vault Particles with Estrogen Receptor in the MCF-7 Breast Cancer Cell

    Get PDF
    A 104-kD protein was coimmunoprecipitated with the estrogen receptor from the flowtrough of a phosphocellulose chromatography of MCF-7 cell nuclear extract. mAbs to this protein identified several cDNA clones coding for the human 104-kD major vault protein. Vaults are large ribonucleoprotein particles of unknown function present in all eukaryotic cells. They have a complex morphology, including several small molecules of RNA, but a single protein species, the major vault protein, accounts for >70% of their mass. Their shape is reminiscent of the nucleopore central plug, but no proteins of known function have been described to interact with them. Western blot analysis of vaults purified on sucrose gradient showed the presence of estrogen receptor co-migrating with the vault peak. The AER317 antibody to estrogen receptor coimmunoprecipitated the major vault protein and the vault RNA also in the 20,000 g supernatant fraction. Reconstitution experiments of estrogen receptor fragments with the major vault protein mapped the site of the interaction between amino acids 241 and 280 of human estrogen receptor, where the nuclear localization signal sequences are located. Estradiol treatment of cells increased the amount of major vault protein present in the nuclear extract and coimmunoprecipitated with estrogen receptor, whereas the anti-estrogen ICI182,780 had no effect. The hormone-dependent interaction of vaults with estrogen receptor was reproducible in vitro and was prevented by sodium molybdate. Antibodies to progesterone and glucocorticoid receptors were able to coimmunoprecipitate the major vault protein. The association of nuclear receptors with vaults could be related to their intracellular traffic
    corecore