Two kinds of companding filters are presented in this dissertation. The first one is a square-root domain filter based on operational transconductance amplifier (OTA). This one is compact and simple. The total are of the circuit excluding pads is 0.013 mm2. The supply voltage is 1.5V and the cutoff frequency can be tuned from 1.1 kHz to 35.2 kHz when the external capacitance C is 1nF. The total harmonic distortions is 0.93% and the power consumption is 152.29 £gW for a 10£gA DC input current. The other one is a tunable log-domain filter. The log domain filters uses parasitic vertical bipolar junction transistor (VBJT) in standard CMOS process for high frequency. The cut-off frequency is from 8.6 MHz to 25.8 MHz and the power dissipation is 585 £gW. All experimental results in a TSMC 0.35 £gm 2P4M CMOS process confirm the feasibility of the methodology.

Texte remanié de: Diss.--Berlin--Humboldt-Universität, 2000. / Bibliogr. p. 225-243. Index.

The number of robotics competitions has steadily increased over the past 30 years. Schools are implementing robotics competitions to increase student content knowledge and interest in science, technology, engineering, and mathematics (STEM). Companies in STEM-related fields are financially supporting robotics competitions to help increase the number of students pursuing careers in STEM among other reasons. These financial supporters and school administrations are asking what the outcomes of students participating in competitive robotics are. Few studies have been conducted to investigate these outcomes. The studies that have been conducted usually compare students in robotics to students not in robotics. There have not been any studies that compare students to themselves before and after participating in robotics competitions. This may be due to the lack of available instruments to measure student outcomes. This study developed an instrument to measure the self-efficacy of students participating in VEX Robotics Competitions (VRC). The VRC is the world’s largest and fastest growing robotics competition available for middle and high school students. Self-efficacy was measured because of its importance to the education community. Students with higher self-efficacy tend to persevere through difficult tasks more frequently than students with low self-efficacy. A person’s self-efficacy has major influence over what interests, activities, classes, college majors, and careers he or she will pursue in life. The self-efficacy survey instrument created through this study was developed through an occupational and task analysis (OTA), and initial content and face validity was established through the OTA process. Exploratory and confirmatory factor analyses were also conducted to assist in instrument validation. The reliability was calculated using Cronbach’s alpha. Face validity was established through the OTA process. Construct validity was established through the factor analyses. The processes of the OTA and factor analyses have created an instrument that results indicate is reliable and valid to use in further research studies.

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This dissertation presents the design and implementation of a 16-channel sinusoidal generator to stimulate microfluidic devices that use electrokinetic forces to manipulate particles. The generator has both, independent frequency and independent amplitude control for each channel. The stimulation system is based upon a CMOS application specific (ASIC) device developed using 0.35¦Ìm technology. Several generator techniques were compared based on frequency range, total harmonic distortion (THD), and on-chip area. The best alternative for the microfluidic applications is based in a triangle-to-sine converter and presents a frequency range of 8kHz to 21MHz, an output voltage range of 0V to 3.1VPP, and a maximum THD of 5.11%. The fabricated device, has a foot- print of 1560¦Ìm¡Á2030¦Ìm. The amplitude of the outputs is extended using an interface card, achieving voltages of 0V to 15VPP. The generator functionality was tested by performing an experimental set-up with particle trapping. The set-up consisted of a micromachined channel with embedded electrodes configured as two electrical ports located at different positions along the channel. By choosing specific amplitude and frequency values from the generator, different particles suspended in a fluid were simultaneously trapped at different ports. The multichannel stimulator presented here can be used in many microfluidic experiments and devices where particle trapping, separation and characterization is desired. / This dissertation presents the design and implementation of a 16-channel sinusoidal generator to stimulate microfluidic devices that use electrokinetic forces to manipulate particles. The generator has both, independent frequency and independent amplitude control for each channel. The stimulation system is based upon a CMOS application specific (ASIC) device developed using 0.35¦Ìm technology. Several generator techniques were compared based on frequency range, total harmonic distortion (THD), and on-chip area. The best alternative for the microfluidic applications is based in a triangle-to-sine converter and presents a frequency range of 8kHz to 21MHz, an output voltage range of 0V to 3.1VPP, and a maximum THD of 5.11%. The fabricated device, has a foot- print of 1560¦Ìm¡Á2030¦Ìm. The amplitude of the outputs is extended using an interface card, achieving voltages of 0V to 15VPP. The generator functionality was tested by performing an experimental set-up with particle trapping. The set-up consisted of a micromachined channel with embedded electrodes configured as two electrical ports located at different positions along the channel. By choosing specific amplitude and frequency values from the generator, different particles suspended in a fluid were simultaneously trapped at different ports. The multichannel stimulator presented here can be used in many microfluidic experiments and devices where particle trapping, separation and characterization is desired.

This thesis is focused on poetics of places and space in the novels of Czech author Ota Filip (*1930). The analysis of individual spaces displayed in Filip's work wants to demonstrate the importance of these places for the narrative construction of the autor's novels. This thesis aims to show the importance of displayed space and individual spaces for the overall sense of the fictional world in the Filip's work. The methodological basis of the thesis is the study of the Polisch scientist Janusz Sławiński: Space in Literature: Basic Division and Introductory Commonplace (2002 [1978]). Research of space displayed in the literary work based on the text of a particular novel.

The e-commerce has increased over the last decades, and this have indicated a change in the booking behaviour within tourism. The change within the tourism business is almost completed to go from offline to online services. This has developed a new form of companies; the online travel agencies (OTAs). As this change has been developed, not all customers is aware of the function of the OTAs. The purpose of this study is to investigate the role of the Kano Model when a third party is involved in the sales through a case study of three OTA sites. This study provides a content analysis with gathered customer reviews. The main findings of this study indicate that the five quality elements of the Kano model may be interrupted by a third party. The customer satisfaction of the OTAs can be decreased by factors that they are not able to control.

L’ocratoxina A (OTA) és un metabòlit secundari tòxic produït per algunes especies fúngiques dels gèneres Aspergillus i Penicillium que poden contaminar aliments i pinsos. Aquesta micotoxina és neurotòxica, hepatotòxica, immunogènica, teratogènica i carcinogènica en animals. En humans, l’exposició crònica a OTA s’ha relacionat amb el desenvolupament de tumors en el tracte urinari i amb la nefropatia endèmica dels Balcans. L’Agència Internacional per a la Investigació en Càncer (IARC) ha classificat l’OTA com a “possiblement carcinògena per als humans”. L’OTA pot estar present en diferents aliments d’origen vegetal com per exemple cereals i derivats, cervesa, cafè, vi i sucs de fruita, fruits secs i fruita deshidratada, cacau i derivats, espècies, i en alguns productes d’origen animal. Aquesta ubiqüitat pot causar en les persones una exposició crònica. L’avaluació de l’exposició d’una població a un determinat contaminant alimentari, en aquesta cas particular l’OTA, pot portar-se a terme mitjançant dos procediments. En primer lloc mitjançant la detecció d’aquest compost en els aliments que suposadament poden estar contaminats per OTA, incloent un estudi dels hàbits de consum de la població avaluada referent als aliments esmentats. En segon lloc, mitjançant l’ús de biomarcardors d’exposició, la qual cosa implica la detecció d’OTA o els seus metabòlits en fluids biològics pertanyents a individus de la població en estudi. L’objectiu general d’aquest treball va ser l’avaluació de la exposició a OTA de determinats grups de persones que habiten a la Comunitat Autònoma de Catalunya mitjançant el càlcul de la ingesta diària d’aquesta toxina. Per a fer-ho es van tenir en compte els procediments anteriorment esmentats: es van adquirir aliments possiblement contaminats procedents d’aquesta zona alhora que es van obtenir les seves dades de consum dels habitants. També es van estudiar els biomarcadors d’exposició, essent els fluids recol·lectats plasma sanguini i orina. La incidència observada en els aliments i fluids biològics estudiats va confirmar l’exposició de la població avaluada a l’OTA. Els nivells de contaminació en els aliments analitzats van ser menors que els valors límit definits per la Comissió Europea, i la seva incidència en la majoria dels casos va ser menor al 50%. Pel que respecta als biomarcadors, la incidència va ser de gairebé el 100% en plasma, menor en orina (12.5%) i es va observar que el metabòlit ocratoxina alfa presentava una major incidència (60.6%) en orina que l’OTA. No es va observar correlació entre els nivells d’OTA en plasma i el consum d’aliments possiblement contaminats però sí que es van observar correlacions significatives entre l’OTA i el seu metabòlit ocratoxina alfa en orina i el consum dels esmentats aliments. Es van observar diferències en els resultats al classificar la població en funció al sexe i l’edat però no es va poder establir una tendència general entre els estudis d’aquest treball. / La ocratoxina A (OTA) es un metabolito secundario tóxico producido por algunas especies fúngicas de los géneros Aspergillus y Penicillium, que pueden contaminar alimentos y piensos. Esta micotoxina es neurotóxica, hepatotóxica, inmunogénica, teratogénica y carcinogénica en animales. En humanos, la exposición crónica a la OTA se ha relacionado con el desarrollo de tumores en el tracto urinario, y con la nefropatía endémica de los Balcanes. La Agencia Internacional para la Investigación en Cáncer (IARC) ha clasificado la OTA como posiblemente carcinógena para los humanos. La OTA puede estar presente en varios alimentos de origen vegetal, como cereales y derivados, cerveza, café, vinos y zumos de uva, frutos secos y fruta deshidratada, cacao y derivados, especias, y en algunos productos de origen animal. Esta ubicuidad puede causar en las personas una exposición crónica. La evaluación de la exposición de una población a un contaminante presente en alimentos, en este caso la OTA, puede llevarse a cabo mediante dos procedimientos principales. En primer lugar, a través de la detección de este compuesto en los alimentos que se supone puedan estar contaminados por OTA, junto con el estudio de los hábitos de consumo de la población evaluada con respecto a los alimentos mencionados. En segundo lugar, mediante el uso de biomarcadores de la exposición, lo cual implica la detección de la OTA o sus metabolitos en fluidos biológicos de individuos de la población estudiada. El objetivo general de este trabajo fue la evaluación de la exposición a OTA por parte de ciertos grupos de personas que habitan en la Comunidad Autónoma de Cataluña, a través del cálculo de la ingesta diaria de la toxina. Para ello se tuvieron en cuenta los procedimientos antes mencionados: se adquirieron en la zona ciertos alimentos posiblemente contaminados, y se obtuvieron datos de consumo de los habitantes. También se estudiaron los biomarcadores de la exposición, y los fluidos recolectados fueron plasma sanguíneo y orina. La incidencia observada en los alimentos y fluidos biológicos estudiados confirmó la exposición de la población evaluada a la OTA. Los niveles de contaminación en los alimentos analizados fueron menores que los valores límite definidos por la Comisión Europea, y la incidencia en la mayoría de los casos fue menor que el 50%. En el caso de los biomarcadores, la incidencia fue de casi el 100% en plasma, menor en orina (12.5%), y se observó que el metabolito ocratoxina alfa presentó una mayor incidencia (60.6%) en orina que la OTA. No se observó correlación entre los niveles de OTA en plasma y el consumo de alimentos posiblemente contaminados, pero se observaron correlaciones significativas entre la OTA y su metabolito ocratoxina alfa en orina y el consumo de alimentos. Se observaron diferencias en los resultados al clasificar la población de acuerdo al sexo y la edad, pero no se pudo establecer una tendencia general entre los estudios de este trabajo. La ingesta diaria de OTA se estimó mediante métodos determinísticos y probabilísticos, utilizando los datos de contaminación y consumo de alimentos. También se estimó teniendo en cuenta los niveles de OTA en plasma, a través de la ecuación de Klaassen. Las ingestas diarias medias y medianas de OTA obtenidas mediante ambas metodologías fueron menores que el valor sugerido por la Autoridad Europea en Seguridad Alimentaria (17 ng/kg peso corporal/día): hasta un 3% de ese valor en el primer caso, y hasta el 10 % en el segundo caso. Sin embargo, se observaron casos atípicos cuando se estimó la ingesta de OTA teniendo en cuenta los niveles de OTA en plasma: esos valores estuvieron en el rango de 14 a 43 ng/kg peso corporal/día. Por lo tanto, la exposición a la OTA no producirá efectos adversos para la salud a la población general evaluada, pero se deberían extremar las medidas para minimizar la exposición, ya que se observaron casos extremos de exposición. / Ochratoxin A (OTA) is a toxic secondary metabolite produced by certain species of the fungal genera Aspergillus and Penicillium that may contaminate foods and feeds. This mycotoxin has nephrotoxic, hepatotoxic, neurotoxic, immunogenic, teratogenic, and carcinogenic properties in animals. In humans, chronic exposure to OTA has been related to the development of tumours in the urinary tract, and to the Balkan endemic nephropathy. The International Agency for Research on Cancer classified OTA as possibly carcinogenic to humans. OTA can be found in several foods of vegetal origin, such as cereals and derivatives, beer, coffee, wines and grape juices, nuts and dried fruits, cocoa and derivatives, spices, and in certain animal by-products. Such ubiquity may lead to a chronic exposure by humans. The assessment of the exposure of a population to a food contaminant, in this case, OTA, can be done through two main procedures. In the first case, through the detection of this compound in the foodstuffs that are supposed to be contaminated by OTA and the study of the consumption habits of the assessed population regarding the mentioned foodstuffs. In the second case, through the use of biomarkers of the exposure, which implies the detection of OTA or its metabolites in biological fluids of individuals of the selected population. The general objective of this work was the evaluation of the exposure to OTA of certain groups of people who live in the Spanish region of Catalonia, through the estimation of the daily intake of the toxin. For this, the procedures mentioned above were followed: possibly contaminated food products were purchased in this region, and consumption data by the inhabitants were collected. Biomarkers of exposure were also studied, and the collected fluids were blood plasma and urine. Occurrence in certain foodstuffs and in body fluids confirmed the exposure of the studied population to OTA. Contamination levels in the analysed foodstuffs were below the limits set by the European Commission, and the occurrence in most cases was below the 50%. In the case of biomarkers, occurrence was almost 100% in plasma, lower in urine (12.5%), and it was observed that the metabolite ochratoxin alpha had a higher incidence (60.6%) in urine than OTA. No correlation was observed between OTA levels in plasma and the consumption of possibly contaminated foodstuffs, but significant correlations were observed between OTA and its metabolite ochratoxin alpha in urine and food consumption. Differences in the results could be observed when the population was classified by gender and age, although a general tendency among the studies of this work could not be established. Regional or seasonal variations of the exposure were not statistically significant. The daily intake of OTA was estimated by deterministic and probabilistic methodologies, by modelling food consumption and contamination data. It was also estimated by considering the levels of OTA in plasma, by means of theKlaassen equation. Mean and median results of daily intake obtained through both methodologies were below the suggested by the European Food Safety Authority (17 ng/kg bw/day): up to 3% of that value, in the first case, and up to 10% in the second. However, outliers were observed when the estimation was done from OTA levels in plasma: such values ranged from 14 to 43 ng/kg bw/day. Therefore, exposure to OTA will not produce adverse health effects to the general assessed population, but further efforts should be invested in order to minimize the exposure, as extreme cases of exposure were observed.