Doctor of Philosophy / Department of Special Education, Counseling and Student Affairs / Kenneth F. Hughey / African American and Latino students continue to experience lower retention and higher attrition rates then their White counterparts. The aim of this qualitative interview study was to understand how African American and Latino students at a predominantly White institution (PWI) achieved graduation in Agriculture-STEM (A-STEM) disciplines. Based on the global need for more A-STEM and STEM professionals and the under-representation of African American and Latino students in the fields, there appeared to be a gap in the research on this population and success attributes with respect to completing undergraduate degrees. There was a tendency in the literature toward examining African American and Latino students utilizing the deficit model. This study explores the lived experiences of two African American and one Latino alumni of A-STEM programs. Understanding the life stories, via counter narratives, of these students may help universities develop stronger support for student success in college for not only African American and Latino students, but for all students in A-STEM disciplines. Critical Race Theory was the framework used for the analysis and the interpretation of the data in this study. The data consisted of interview transcripts, timeline, documents, photographs, and e-mail conversations. Communicating the findings in qualitative interview studies is the result of constructing the experiences and meanings of events through the eyes of the participants in a manner that portrays a representation of their experiences. Each participant’s counter narratives were created to highlight salient patterns reflected in their experiences. The writing around the participants’ experiences, and the interrogation of data allowed for the identification of patterns that were consistent with each participant’s stories and their individual unique details. The findings revealed: (a) ethnic minority students want faculty and administrators who looked like them because having someone to understand their experiences as people of color in PWI is needed; (b) the need for organizations that support ethnic minority student academic and social success, which in turn helps to create a sense of belongingness and a more inclusive campus climate; (c) more overall faculty support in and out of the classroom; and (d) opportunities for involvement in faculty-led research projects.

Orientador: Elnatan Chagas Ferreira / Texto em inglês / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-20T11:54:01Z (GMT). No. of bitstreams: 1 Dias_PedroCarvalhaes_M.pdf: 7362254 bytes, checksum: dd839cf652cbbda17a2a5d9b6cecbdc3 (MD5) Previous issue date: 2012 / Resumo: A constante preocupação em aumentar a produtividade das plantações de uma forma sustentável e otimizando o uso dos insumos agrícolas (água, fertilizantes, pesticidas e produtos para correção do PH) levou ao desenvolvimento da agricultura de precisão, que permite determinar a quantidade correta de insumos para cada região do solo (tipicamente um hectare), evitando o desperdício. Sensores de umidade de solo de baixo custo e fácil aplicação no campo são fundamentais para permitir um controle preciso da atividade de irrigação, sendo que os sensores que melhor atendem estes requisitos são os chamados sensores de dissipação de calor ou sensores de transferência de calor. Estes sensores, entretanto, apresentam um problema de baixa sensibilidade na faixa de umidade mais importante para as plantas (umidade de solo 'teta'v variando entre 5% e 35%), pois, para cobrir esta variação de 30% em 'teta'v com resolução de 1%, é necessário medir variações de temperatura de aproximadamente 0,026 ºC nos sensores de pulso de calor a duas pontas e 0,05 ºC para os sensores de pulso de calor de ponta simples. Neste trabalho foi desenvolvido um novo sensor de umidade de solo do tipo pulso de calor de ponta simples, baseado em um único elemento: um transistor bipolar de junção npn, que é usado tanto como aquecedor e como sensor de temperatura de alta precisão. Resultados experimentais, obtidos em medidas realizadas através de uma técnica de interrogação especialmente desenvolvida para este novo sensor mostram que neste trabalho foi possível obter uma sensibilidade cerca de uma ordem de grandeza maior do que nos sensores de pulso de calor com uma ponta e cerca de 20 vezes maior do que nos sensores de pulso de calor de duas pontas. Outra vantagem da técnica desenvolvida é que o aumento da sensibilidade não é obtido às custas do aumento da corrente drenada da bateria para aquecer o sensor. No sensor desenvolvido é utilizada uma corrente de apenas 6 mA para gerar o aquecimento (com energia dissipada de 1,5 J), enquanto que que os sensores de pulso de calor com ponta simples requerem cerca de 50 mA (com 2,4 J de energia dissipada) para operar. Os sensores de pulso de calor de ponta dupla também são fabricados com resistores que requerem cerca de 50 mA para o aquecimento (0.8 J de energia dissipada) para operar corretamente / Abstract: The concern regarding sustainable development and crop inputs optimization (such as water, fertilizers, pesticides and soil PH correction products) has led to the development of the precision agriculture concept, that allows to determine the exact amount of each input required on each ground section (typically one hectare), avoiding waste of inputs. Low-cost and easily handled soil moisture sensors are very important for allowing a precise irrigation control. The class of sensors which fulfill those requirements are the heat transfer sensors, where there are basically two types of devices: dual (or multi) probe heat pulse sensors and single probe heat pulse sensors. However, these sensors have a low sensitivity in the most important range of soil humidity 'teta'v for plants (usually from 5% ? 'teta'v ? 35%). To cover this 30% soil humidity range with 1% resolution it is necessary to measure temperature with a resolution of 0,026 ºC in the dual/multi probe heat pulse sensors and 0,05 ºC in the single probe heat pulse sensor. In this work it was developed a new type of single probe heat pulse sensor, comprised of a single element: an npn junction bipolar transistor, that plays the role of both the heating element and a high accuracy temperature sensor. Experimental results, obtained through an interrogation technique especially developed for this sensor, show sensitivity about one order of magnitude greater than the typical sensitivity of the single probe heat pulse sensors and 20 times greater than dual probe heat pulse sensors. Another great advantage of the developed interrogation technique is that the increase in sensibility is not obtained through a higher current being drained from the batteries that power the sensor. The developed sensor operates at a much lower current level than the other sensors, draining only 6 mA from the battery (with an energy of 150 mW). The single probe heat pulse sensor requires 50 mA and 1.5 J of energy to operate, whilst the dual probe heat pulse sensors are manufactured with resistors which also drain 50 mA from the battery with 0.8 J of dissipated energy / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica

Thesis (MBA)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: This study evaluates the use of information technology as a method to reduce production risk for irrigated potatoes. Risk in agriculture is discussed under climatic, market or price and production related risk. Production related risk covers the disciplines of planting, irrigation, fertilisation, disease and pest control as well as harvesting. It is in the above mentioned disciplines that information technology could possible be applied to reduce production risk in irrigated potatoes. The nature of this study can therefor be described as the investigation of the economic justification of information technology as a method to reduce production risk in irrigated potatoes. A brief introduction to put potato production in world and South African context into perspective, is provided. In South African context the importance and position of potato production relative to other crops is discussed. To better understand the economic conditions, under which potatoes are produced in South Africa, a financial breakdown of production cost for irrigated potatoes over regions is given. It is important to understand the economics of potato production before a proper assessment of thepossible benefits of information technology can be made. Various principles and instruments involved with information technology, as it applies to potato production under irrigation are also discussed. Irrigation scheduling as a discipline in which information technology can be applied, is also discussed. It is important to understand that irrigation scheduling can be based on two underlying principles, i.e. atmospheric modelling and soil moisture measurement. Various examples of measurement instruments are discussed. Climatic based disease modelling and petiole sampling as a method to determine nutritional status in the potato plant, was also discussed. A brief discussion of computerised agriculture management software was included to conclude the discussion on the principles and instruments available for information technology in irrigated potato production. The use of fertiliser scheduling, irrigation scheduling and climatic modelling to reduce fungal diseases in potatoes, as information technology methods, are explained in greater detail. It is shown that recommended levels for various nutrients do exist and that petiole analysis as a method to determine these levels at various growth stages, can be applied successfully. It is further argued that with various methods of irrigation scheduling, proper decision making about the amount and timing of irrigation needed, can be possible. The Plant-Plus system as a method to better control Late Blight on potatoes, is discussed. The results obtained through a commercial trial proves the validity of climatic modelling as a method of information technology to reduce production risk on potatoes, specifically the risk associated with Late Blight. The existence of and results obtained through the equipment and methods previuosly mentioned, raises the question of the economic viability of information technology at farm level. To investigate the perception of growers with regard to the applicability of information technology to reduce production risk and their readiness to adopt such . -- technology, a questionnaire was sent to 40 commercial potato growers throughout South Africa. Growers were tested on their perception with regard to the use of information technology on aspects such as financial management, irrigation scheduling, fertilisation, climatic measurement for fungal modelling as well as a profile analysis of the grower. The results of the survey are tabulated and analysed. Growers were on average positive about the value of information technology and indicated that under certain conditions, they were prepared to implement such technology. Margins in commercial potato production are under severe pressure and are in fact shrinking. Case studies presented in this investigation and results from the pilot survey indicate that the use of information technology is not only important for the reduction of risk in potato production but also imperative for sustainable and profitable potato production. It can therefore be concluded that, based on the results obtained in the pilot questionnaire, a statistical valid sample would probably support the findings in the pilot study. The pilot study indicated that reliable, affordable and practical information technology, as it has been presented in this investigation, does have a place in modern day irrigated potato production. / AFRIKAANSE OPSOMMING: Hierdie studie evalueer die gebruik van informasie tegnologie as 'n metode om produksie risiko in die verbouing van aartappels onder besproeiing, te verminder. Risiko in landbou word onder klimatologiese, mark of prys en produksie verwante risiko bespreek. Produksie verwante risiko kan weer onderverdeel word in risiko wat verband hou met plant of vestiging, besproeiing, bemesting, plaag en pes beheer asook oes. Dit is dan in die bogenoemde dissiplines waar informasie tegnologie moontlik aangewend kan word om produksie verwante risiko te verminder. Die kern van hierdie ondersoek kan gevolglik saamgevat word as 'n ondersoek na die ekonomiese regverdigbaarheid van informasie tegnologie as 'n metode om produksierisiko in die verbouing van aartappels onder besproeiing, te verminder. Daar word kortliks verwys na aartappel verbouing in wêreld en Suid Afrikaanse konteks. In Suid Afrikaanse konteks is die relatiewe belangrikheid van aartappelverbouing in vergelyking met ander gewasse uitgelig. Ten einde 'n beter begrip vir die ekonomiese omstandighede waaronder aartappels in Suid Afrika verbou word, word 'n afbraak van produksiekoste oor streke verskaf Dit is belangrik om die ekonomie van aartappelproduksie te verstaan voordat 'n deeglike evaluering van die moontlike voordele wat informasie tegnologie kan inhou, onderneem kan word. Verskeie beginsels en instrumente in die aanwending van informasie tegnologie, soos van toepassing in die verbouing van aartappels onder besproeiing, word ook toegelig. Hieronder word besproeiingskedulering as 'n metode bespreek. Dit is verder belangrik om te besef dat besproeiingskedulering op hoofsaaklik twee beginsels berus naamlik atmosferiese modellering en fisiese grondvog meting. Verskeie voorbeelde van meetinstrumente word bespreek. Klimatologiese siektemodellering en petioolontledings as 'n metode om die voedingstatus van aartappelplante te bepaal, word ook bespreek. Die gebruik van bemestingskedulering, besproeiingskedulering en klimatologiese modellering vir die beheer van laatroes op aartappels, as metodes van informasie tegnologie, word in groter besonderhede toegelig. Daar is aangetoon dat aanbevole peile vir verskeie nutriënte bestaan. Deur die neem van gereelde petiool ontledings kan hierdie peile suksesvol gedurende die opeenvolgende fenologiese stadia van die aartappelplant, gehandhaaf word. Daar is verder aangevoer dat deur die gebruik van verskeie metodes van besproeiingskedulering, deeglike besluitneming rakende die hoeveelheid en tydsberekening van 'n besproeiing, moontlik is. Die Plant-Plus sisteem as 'n metode om laatroes op aartappels te beheer, is toegelig. Resultate behaal in 'n kommersiële aanplanting het die geldigheid van klimatologiese modellering as 'n metode om produksierisiko - veral die risiko geassosieer met laatroes - te verminder, onderskryf. Die bestaan van resultate en instrumente soos voorgehou in Hoofstukke 3 en 4, onderskryf of bevestig die vermoede dat informasie tegnologie wel aangewend kan word om produksierisiko in aartappelverbouing te verminder. Die vraag is egter of dit ekonomies op plaasvlak aangewend kan word. Ten einde die persepsie met betrekking tot - die toepaslikheid en gereedheid van produsente in dié verband te evalueer, is 'n loodsvraelys na 40 respondente, wat die kommersiële aartappelprodusente regdeur Suid Afrika verteenwoordig, gestuur. Respondente is ge-evalueer met betrekking tot hul persepsie rakende die gebruik van informasie tegnologie in die dissiplines van finansiële bestuur, besproeiingskedulering, nutriëntskedulering en klimatologiese modellering vir die beheer van laatroes. Respondente was oor die algemeen positief met betrekking tot die nut van informasie tegnologie en dat onder seker voorwaardes, hulle dit sal gebruik. Marges in kommersiële aartappelverbouing is onder ernstige druk en is inderdaad besig om te krimp. Gevallestudies wat in hierdie ondersoek voorgehou is, asook resultate verkry uit die vraelys, dui aan dat informasie tegnologie nie alleen belangrik is vir die vermindering van risiko in aartappelverbouing me, maar ook noodsaaklik IS vir volhoubare en winsgewende aartappelproduksie. Dit kan gevolglik gestel word dat resultate verkry uit die loodsvraelys, daarop mag dui dat 'n statisties verifieerbare steekproef moontlik kan uitwys dat betroubare, bekostigbare en praktiese informasie tegnologie, soos voorgehou in hierdie ondersoek, wel 'n bestaansreg in die moderne verbouing van aartappels onder besproeiing het.