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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Effects of manure application upon water quality of surface runoff from rainfall simulation tests

Chen, I-Chun (Jean) 11 October 2005
Manure contains nutrients for crop growth; however, overapplication, with time, can result in excess nutrients in soil, which can subsequently be lost in surface runoff. <p>The general purpose of this research is to study the effect of liquid hog manure, applied as an agricultural fertilizer, on water chemistry of surface runoff from rainfall simulation tests. Specifically the research focuses on runoff water chemistry comparisons between lands receiving hog manure at different rates, via different injection methods, and upon different slope positions. <p>To examine these objectives, soil nutrient supply rates (P, NH4-N, and NO3-N) of the 0 5 cm depth of soil adjacent to rainfall simulation positions, and runoff water chemistry (TP, OP, NH4-N, NO3-N, DOC, Cl- and coliforms) during rainfall simulation tests were collected before and after manure addition. <p> Generally, manure application did increase soil NH4-N and NO3-N supply rates, and runoff NH4-N concentration. Soil P supply rate and runoff TP concentration were not affected by the manure addition; however, runoff OP concentration at one site (Perdue) increased significantly due to manure addition. The manure treatments applied in this study did not cause any significant increases in fecal or total coliform in runoff from rainfall simulation tests conducted 7 8 months after manure application. None of the water quality parameters exceeded the Guidelines for Canadian Drinking Water Quality. <p> Manure injection method (regular versus low soil surface disturbance) had consistent effects on runoff chemistry, but application rate did not. The regular disturbance method had significantly higher concentrations of water quality parameters than the low disturbance method. <p> The position of the test on the slope did not result in any consistent trends in runoff chemistry, whether before or after manure addition. Foot slope positions had higher soil NH4-N supply rates than upper slope positions, both before and after manure addition. Soil NH4-N, NO3-N, and P supply rates between landscape positions were not likely influenced by manure addition. <p> Regression tests between soil nutrient supply rates and runoff chemistry indicate that soil NH4-N supply rates are a good index to predict runoff NH4-N concentration, but soil P did not predict runoff P.
22

Effects of manure application upon water quality of surface runoff from rainfall simulation tests

Chen, I-Chun (Jean) 11 October 2005 (has links)
Manure contains nutrients for crop growth; however, overapplication, with time, can result in excess nutrients in soil, which can subsequently be lost in surface runoff. <p>The general purpose of this research is to study the effect of liquid hog manure, applied as an agricultural fertilizer, on water chemistry of surface runoff from rainfall simulation tests. Specifically the research focuses on runoff water chemistry comparisons between lands receiving hog manure at different rates, via different injection methods, and upon different slope positions. <p>To examine these objectives, soil nutrient supply rates (P, NH4-N, and NO3-N) of the 0 5 cm depth of soil adjacent to rainfall simulation positions, and runoff water chemistry (TP, OP, NH4-N, NO3-N, DOC, Cl- and coliforms) during rainfall simulation tests were collected before and after manure addition. <p> Generally, manure application did increase soil NH4-N and NO3-N supply rates, and runoff NH4-N concentration. Soil P supply rate and runoff TP concentration were not affected by the manure addition; however, runoff OP concentration at one site (Perdue) increased significantly due to manure addition. The manure treatments applied in this study did not cause any significant increases in fecal or total coliform in runoff from rainfall simulation tests conducted 7 8 months after manure application. None of the water quality parameters exceeded the Guidelines for Canadian Drinking Water Quality. <p> Manure injection method (regular versus low soil surface disturbance) had consistent effects on runoff chemistry, but application rate did not. The regular disturbance method had significantly higher concentrations of water quality parameters than the low disturbance method. <p> The position of the test on the slope did not result in any consistent trends in runoff chemistry, whether before or after manure addition. Foot slope positions had higher soil NH4-N supply rates than upper slope positions, both before and after manure addition. Soil NH4-N, NO3-N, and P supply rates between landscape positions were not likely influenced by manure addition. <p> Regression tests between soil nutrient supply rates and runoff chemistry indicate that soil NH4-N supply rates are a good index to predict runoff NH4-N concentration, but soil P did not predict runoff P.
23

Study of the Expression of Genes involved in Defense pathways and Epigenetic Mechanisms in tomato infected with Stolbur Phytoplasma / Etude de l'expression de gènes impliqués dans les voies de défense et les mécanismes épigénétiques chez la tomate infectée par le phytoplasme du stolbur

Ahmad, Jam Nazeer 20 December 2011 (has links)
Les phytoplasmes sont des bactéries phytopathogènes, sans paroi, qui appartenant à la classe des Mollicutes. Ils ne peuvent pas etre cultivés in vitro et sont limités à des tubes du phloème. Ils provoquent des centaines de maladies chez de nombreuses espèces végétales dans le monde entier, ce qui conduit à des pertes de récolte importantes. Les phytoplasmes sont transmis naturellement par des insectes suceurs de sève dans laquelle ils se multiplient. Ils induisent des symptômes graves, notamment le jaunissement, la croissance limitée, déclin, ainsi que des anomalies des fleurs et des fruits. L'infection par le phytoplasme du stolbur, en particulier, affect fortement la morphologie florale. Dans la tomate, deux isolats différents du phytoplasme du stolbur, nommé C et PO, induisent des symptômes différents. La tomate infectée par le phytoplasme du stolbur PO montrent des malformations florale telles que les sépales hypertrophiés, les pétales et les étamines avortées ce qui conduit à la stérilité. En revanche, la tomate infecté par le phytoplasme du stolbur C ont de petites feuilles de tomate en retrait, mais les fleurs presque normale, et produisent des fruits. Nous avons précédemment montré que SlDEF, un gène impliqué dans la formation des pétales est réprimé dans des plantes de tomate infectée par le stolbur phytoplasme PO. Toutefois, l'expression de son facteur de transcription, codée par le gène FA, est resté stable ou voir légèrement augmentée. Nous avons donc émis l'hypothèse que la répression de SlDEF pourrait être dû à une méthylation de l'ADN. Pour tester cette hypothèse, nous avons étudié l'expression des gènes de méthylases et de déméthylases. Ils étaient en général réprimés dans les tomates infectées par le phytoplasme du stolbur PO, ce qui était en accord avec l'hypothèse De plus, nous avons étudié les voies de défense activée chez les tomates infectées par le phytoplasme du stolbur. Pour se défendre, les plantes utilisées des molécules de signalisation comme l'acide salicylique (SA), l'acide jasmonique (JA) et d'éthylène (ET). Nous avons étudié l'expression de 21 gènes de défense dépendants SA / JA / ET, des gènes de biosynthèse et les facteurs de transcription chez les tomates infectées par les phytoplasmes du stolbur C et PO. Nous avons également étudié l'effet de la pré-activation des voies de SA et JA sur la production des symptômes. Nos résultats montrent clairement que les voies de défense ont été activées différemment dans les tomates infectés par le phytoplasme du stolbur C et PO. En effet, les voies de défense dépendantes de SA, ET et JA ont été activées chez les tomates infectées par le phytoplasme du stolbur C alors que seulement les voies dépendantes SA et ET ont été activés dans les tomates infectées par stolbur PO . En outre, la pré-activation de la voie de défense dépendante SA par l'application de BTH modifie légèrement l'évolution des symptômes de maladies causées par le phytoplasme du stolbur PO / Phytoplasma are cell wall-less, phytopathogenic bacteria belonging to the class Mollicutes. They have not been cultured in vitro and are restricted to the phloem sieve tubes. They cause hundreds of diseases in many plant species worldwide, resulting in important crop losses. Phytoplasmas are naturally transmitted by sap-sucking insects in which they multiply. They induce severe symptoms including yellowing, restricted growth, decline, as well as major flowers and fruits abnormalities.The stolbur phytoplasma infection, in particular, has been reported to strongly affect floral morphology. In tomato, two different isolates of stolbur phytoplasma, named C and PO, induce different symptoms. The stolbur PO phytoplasma-infected plants show abnormal flower development such as hypertrophied sepals, and aborted petals and stamens leading to sterility. In contrast, stolbur C phytoplasma-infected tomato have small indented leaves but nearly normal flowers, and produce fruits. We have previously shown that SlDEF, one gene involved in petal formation, was repressed in stolbur PO phytoplasma-infected tomato. However, the expression of its transcription factor, encoded by the gene FA, was unchanged or slightly up-regulated. So we hypothesized that SlDEF repression could be due to DNA methylation. To test this hypothesis, we studied the expression of DNA methylases and demethylases genes. They were in general down-regulated in stolbur PO infected tomato, which was in agreement with the hypothesis. However, the regulation of SlDEF expression could not be firmly correlated to the DNA methylation status of its promoter region. In addition, we studied the plant defense pathways activated in stolbur phytoplasma-infected tomato. To defend themselves, plants used signalling molecules like Salicylic acid (SA), Jasmonic acid (JA) and Ethylene (ET). We studied the expression of 21 SA/JA/ET regulated defense and biosynthesis genes including transcription factors in stolbur C and PO phytoplasma-infected tomato as compared to healthy ones. We also studied the effect of pre-activation of SA and JA mediated defense pathways on symptom production. Our results clearly showed that defense pathways were activated differently in stolbur C and PO phytoplasma-infected tomato. Indeed, SA ET and JA dependant pathways were activated in stolbur C-infected tomato while only SA and ET dependant pathways were activated in stolbur PO-infected plants. In addition, pre-activation of SA-dependent defense pathway by application of BTH slightly modify the evolution of disease symptoms caused by stolbur PO phytoplasma whereas no effect was observed after treatment with an analogue of JA.
24

Refining the Use of Polygenic Risk Scores for Alzheimer's Disease in Diverse and Founder Populations

Osterman, Michael David 26 May 2023 (has links)
No description available.
25

大台北地區計程車駕駛人收聽警察廣播電臺轉台行為分析 / An analysis of taxi drivers' channel-switching patterns while listening to the PRS in Taipei

林秋綿, Lin, Chiu Mien Unknown Date (has links)
本研究以警察廣播電臺台北臺為例,探討身為交通專業電台的警察廣播電台,在面對電視與其他廣播媒體,紛紛加入路況資訊提供的競爭下,是否仍具有其優勢?以因工作需要而必需長時間使用道路的計程車駕駛人為研究對象,探討大台北地區計程車駕駛人收聽警廣節目的主要目的為何?在什麼情況下容易轉台?節目內容與傳播設備等因素,是否也會影響計程車駕駛人的轉台意願? 研究發現,收聽警廣台北臺節目的計程車駕駛人,只有兩種類型,一種為「計劃型」收聽,另一種則採取「再評估模式」。計程車駕駛人因警廣路況報導正確而收聽,但卻也會因為資訊不夠即時而轉台;收聽時間大多集中在上、下班的尖峰時間。最欣賞的節目主持人,則以「路況報得好、報得專業」最獲青睞,甚至有六成以上的計程車駕駛人會因為喜歡某個節目主持人,而固定收聽其節目;另外,聲音悅耳、節目多元豐富與音樂好聽與否,也是吸引計程車駕駛人是否繼續收聽的重要因素。除了路況資訊的獲得外,計程車駕駛人對於生活資訊的需求,遠高於新聞氣象、綜藝音樂及公共事務。至於車上有無其他音響設備,亦將影響計程車駕駛人的轉台行為。 / The purpose of this study is to determine whether the Police Radio Station (PRS), specifically the one in Taipei, is still necessary since television and many other forms of media provide the same service of traffic broadcasting. The research subjects for this study are Taipei taxi drivers who spend long hours on the road each day. Four questions form the basis of this study: 1. What is the main reason that taxi drivers listen to PRS? 2. Under what circumstances do they switch channels? 3. Does the content of the program affect their listening choices? 4. Does the type of broadcasting equipment affect their listening choices? The results indicate that there are two kinds of taxi drivers who listen to the programs of the PRS in Taipei. The first kind follows the "planning strategy" and the other kind follows the "re-evaluation strategy." Drivers listen to the PRS for its accuracy of traffic information; however, they will switch to another channel when there is a lack of substantial information being broadcast. Their listening time usually occurs during the rush hours, when they are getting on or getting off work. Drivers primarily prefer anchors whose information is "not only great but also professional." More than 60 percent of the drivers in this study report that they will continuously listen to one program if it is hosted by the anchor whom they favor. In addition, three other factors affect the drivers' listening habits: (1) the voice of the anchor, (2) the richness of the program content, and (3) the quality of the music being played. Besides traffic information, taxi drivers also need or desire to listen to information about other aspects of daily life, than (1) news and weather, (2) entertainment, and (3) public affairs. Finally, one other factor affects the listening behavior of taxi drivers: whether or not there is more than one form of listening device inside the car.

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