10 resultados para Field supervision and work conditions

em Digital Commons at Florida International University


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The present research evidences a field setting studying attitudinal and behavioral results of five Black group contacts. The research was designed, in part, to determine the demographic, cultural, social, and psychological factors associated with intrablack perceptions of conflict and work attitudes in an African American organization. Two organizational groups, African Americans and Caribbean/West Indians totaling 112 participants were studied. The objective of the research was to gain information about attitudinal levels perceived by each of the two groups. Each group rated the other group on items dealing with conflict and work attitudes. One-way analysis of variances (ANOVAs) were employed to test the overall differences on scale means among the groups. The findings in this study buttress some of the major themes in the impressionistic literature on cultural/multicultural diversity in organizations and Caribbean/West Indian literature. The data are reported and examined, and theoretical implications are discussed. ^

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The aim of this research was to demonstrate a high current and stable field emission (FE) source based on carbon nanotubes (CNTs) and electron multiplier microchannel plate (MCP) and design efficient field emitters. In recent years various CNT based FE devices have been demonstrated including field emission displays, x-ray source and many more. However to use CNTs as source in high powered microwave (HPM) devices higher and stable current in the range of few milli-amperes to amperes is required. To achieve such high current we developed a novel technique of introducing a MCP between CNT cathode and anode. MCP is an array of electron multipliers; it operates by avalanche multiplication of secondary electrons, which are generated when electrons strike channel walls of MCP. FE current from CNTs is enhanced due to avalanche multiplication of secondary electrons and in addition MCP also protects CNTs from irreversible damage during vacuum arcing. Conventional MCP is not suitable for this purpose due to the lower secondary emission properties of their materials. To achieve higher and stable currents we have designed and fabricated a unique ceramic MCP consisting of high SEY materials. The MCP was fabricated utilizing optimum design parameters, which include channel dimensions and material properties obtained from charged particle optics (CPO) simulation. Child Langmuir law, which gives the optimum current density from an electron source, was taken into account during the system design and experiments. Each MCP channel consisted of MgO coated CNTs which was chosen from various material systems due to its very high SEY. With MCP inserted between CNT cathode and anode stable and higher emission current was achieved. It was ∼25 times higher than without MCP. A brighter emission image was also evidenced due to enhanced emission current. The obtained results are a significant technological advance and this research holds promise for electron source in new generation lightweight, efficient and compact microwave devices for telecommunications in satellites or space applications. As part of this work novel emitters consisting of multistage geometry with improved FE properties were was also developed.

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The high-pressure and temperature investigations on transition metals, metal doped-oxide system, nanocrystalline materials are presented in this dissertation. The metal-doped oxide systems are technologically important because of their applications, e.g. LSC, opto electronic applications, luminescence from lasers, etc., and from the earth sciences point of view, e.g. the study of trace elements in the MgO-SiO2 system, which accounts for 50% of the Earth's chondritic model. We have carried out thorough investigations on Cr2O3 and on chromium bearing oxides at high PT-conditions using in situ X-ray diffractometry and florescence spectroscopy techniques. Having obtained exciting results, an attempt to focus on the mechanism of the coordination of transition metals in oxides has been made. Additionally, the florescence from the metals in host oxides was found to be helpful to obtain information on structural variations like changes in the coordination of the doped element, formation of new phases, the diffusion processes. The possible reactions taking place at extreme conditions in the MgO-SiO2 system has been observed using florescence as markers. A new heating assemblage has been designed and fabricated for a precise determination of temperature at high pressures. An equation combining pressure shifts of ruby wavelength and temperature has been proposed. We observed that the compressibility of nanocrystalline material (MgO and Ni) is independent of crystallite size. A reduction in the transition pressure of nanocrystalline ceria at high-pressure has been observed as compare to the corresponding bulk material. ^

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Inverters play key roles in connecting sustainable energy (SE) sources to the local loads and the ac grid. Although there has been a rapid expansion in the use of renewable sources in recent years, fundamental research, on the design of inverters that are specialized for use in these systems, is still needed. Recent advances in power electronics have led to proposing new topologies and switching patterns for single-stage power conversion, which are appropriate for SE sources and energy storage devices. The current source inverter (CSI) topology, along with a newly proposed switching pattern, is capable of converting the low dc voltage to the line ac in only one stage. Simple implementation and high reliability, together with the potential advantages of higher efficiency and lower cost, turns the so-called, single-stage boost inverter (SSBI), into a viable competitor to the existing SE-based power conversion technologies.^ The dynamic model is one of the most essential requirements for performance analysis and control design of any engineering system. Thus, in order to have satisfactory operation, it is necessary to derive a dynamic model for the SSBI system. However, because of the switching behavior and nonlinear elements involved, analysis of the SSBI is a complicated task.^ This research applies the state-space averaging technique to the SSBI to develop the state-space-averaged model of the SSBI under stand-alone and grid-connected modes of operation. Then, a small-signal model is derived by means of the perturbation and linearization method. An experimental hardware set-up, including a laboratory-scaled prototype SSBI, is built and the validity of the obtained models is verified through simulation and experiments. Finally, an eigenvalue sensitivity analysis is performed to investigate the stability and dynamic behavior of the SSBI system over a typical range of operation. ^

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Interest in the health of marine mammals has increased due, in part, to the attention given to human impact on the marine environment. Recent mass strandings of the Atlantic bottlenose dolphin (Tursiops truncatus) and rising mortalities of the endangered Florida manatee (Trichechus manatus latirostris) have raised questions on the extent to which pollution, infectious disease, "stress," and captivity influence the immune system of these animals. This study has provided the first in-depth characterization of immunocytes in the peripheral blood of dolphins (n = 190) and manatees (n = 56). Immunocyte morphology and baseline values were determined in clinically normal animals under free-ranging, stranded and captive living conditions as well as by age and sex. Additionally, immunocyte population dynamics were characterized in sick animals. This was accomplished with traditional cytochemical techniques and new lymphocyte phenotyping methodology which was validated in this study. Traditional cytochemical techniques demonstrated that blood immunocyte morphology and cell numbers are similar to terrestrial mammals with some notable exceptions. The manatee heterophilic granulocyte is a morphologically unique cell and probably functions similarly to the typical mammalian neutrophil. Eosinophils were rarely found in manatees but were uncommonly high in healthy and sick dolphins. Basophils were not identified. Manatees had higher total lymphocyte numbers compared to dolphins and most terrestrial mammals. Lymphocyte subsets identified in healthy animals included T$\rm\sb{h}$, T$\rm\sb{c/s}$, B and NK cells. Dolphin and manatee T and B cell values were higher than those reported in man and most terrestrial mammals. The manatee has extraordinarily high absolute numbers of circulating T$\rm\sb{h}$ cells which suggests an enhanced immunological response capability. With few exceptions, immunocyte types and absolute numbers were not significantly different between free-ranging, stranded and captive categories or between sex and age categories. The evaluation of immunocyte dynamics in various disease states demonstrated a wide variation in cellular responses which provided new insights into innate, humoral and cell-mediated immunity in these species. Additionally, this study demonstrated that lymphocyte phenotyping has diagnostic significance and could be developed into a potential indicator of immunocompetence in both free-ranging and captive dolphin and manatee populations.

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This flyer promotes the event "The Life and Work of Severo Sarduy: A Conversation with Mercedes Sarduy and Catalina Quesada".

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Professor Clement Fatovic, Director of Graduate Studies for Politic Sciences, lectures on the subject of the American Founding. Lecture held at the Green Library, Modesto Maidique Campus, Florida International University, on April 10, 2013.

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Interest in the health of marine mammals has increased due, in part, to the attention given to human impact on the marine environment. Recent mass strandings of the Atlantic bottlenose dolphin (Tursiops truncatus) and rising mortalities of the endangered Florida manatee (Trichechus manatus latirostris) have raised questions on the extent to which pollution, infectious disease, "stress," and captivity influence the immune system of these animals. This study has provided the first in-depth characterization of immunocytes in the peripheral blood of dolphins (n=180) and manatees (n=56). Immunocyte morphology and baseline values were determined in clinically normal animals under free-ranging, stranded and captive living conditions as well as by age and sex. Additionally, immuocyte population dynamics were characterized in sick animals. This was accomplished with traditional cytochemical techniques and new lymphocyte phenotyping methodology which was validated in this study. Traditional cytochemical techniques demonstrated that blood immunocyte morphology and cell numbers are similar to terrestrial mammals with some notable exceptions. The manatee heterophilic granulocyte is a morphologically unique cell and probably functions similarly to the typical mammalian neutrophil. Eosinophils were rarely found in manatees but were uncommonly high in healthy and sick dolphins. Basophils were not identified. Manatees had higher total lymphocyte numbers compared to dolphins and most terrestrial mammals. Lymphocyte subsets identified in healthy animals included Th, Tes, B and NK cells. Dolphin and manatee T and B cell values were higher than those reported in man and most terrestrial mammals. The manatee has extraordinarily high absolute numbers of circulating Th cells which suggests an enhanced immunological response capability. With few exceptions, immunocyte types and absolute numbers were not significantly different between free-ranging, stranded and captive categories or between sex and age categories. The evaluation of immunocyte dynamics in various disease states demonstrated a wide variation in cellular responses which provided new insights into innate, humoral and cell-mediated immunity in these species. Additionally, this study demonstrated that lymphocyte phenotyping has diagnostic significance and could be developed into a potential indicator of immunocompetence in both free-ranging and captive dolphin and manatee populations.

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This study examines the role of race, socioeconomic status, and individualism-collectivism as moderators of the relationship between selected work and family antecedents and work-family conflict and evaluates the contribution of energy-based conflict to the work-family conflict (WFC) research. The study uses data obtained from a survey questionnaire given to 414 participants recruited from an online labor market. Study hypotheses were tested through structural equation modeling. The results indicate that while moderating effects were slight, a proposed model where energy-based conflict is included outperforms traditional time/strain/behavior-based models and that established variables may drop to non-significance when additional variables are included in prediction. In addition, novel individual difference variables such as individualism and collectivism were demonstrated to have effects beyond moderating antecedent-outcome relationships in the model. The findings imply that WFC models would benefit from the inclusion of variables found in the current study.

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Several researchers have investigated the effects of alcohol on memory. Few researchers have studied the effects of alcohol on an eyewitness's recall and recognition of crime events. This study proposed to examine the effects of alcohol and viewing conditions on subjects' ability to recall information regarding a videotaped bank robbery. Thirty male and 22 female subjects participated in a 2 (consumption: alcohol v. no alcohol) x 2 (lighting: good v. poor) factorial experiment with Average Accuracy and Total Amount of Information recalled as the primary dependent measures. There was no significant difference between the Intoxicated and Sober subjects regarding the amount of information recalled or their average accuracy. The main effect for lighting conditions and gender differences were also not significant.