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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.
1

The effect of porosity distribution on the predicted mechanical response of die cast AM60B magnesium

Hardin, David Barrett 07 August 2010 (has links)
In this paper, it is clearly shown that the distribution of the initial porosity is a critical factor in the prediction of damage evolution and initiation of failure in a cast AM60B magnesium notch Bridgeman tensile specimen. Using X-ray computed tomography, the actual initial porosity distribution was obtained, and this distribution was input into a finite element code as an initial condition. The predicted damage evolution from this simulation was compared to the damage evolution of the experimental specimen as well as other simulated porosity distributions. This study shows that the simulation of the actual porosity distribution predicted well the damage evolution observed in the experiment. It is also shown that the initial distribution of porosity plays a vital role in the predicted elongation to failure of a notched specimen. The actual distribution was shown to fail at a significantly lower strain than random or uniformly distributed damage.
2

Factors affecting energy absorption of a plate during shock wave impact using a damage material model

Crosby, Zachary Kyle 07 August 2010 (has links)
This thesis examines the influences of five factors on the strain energy at failure of metallic alloy plates during a shock wave impact. The five factors are material type, initial damage, boundary conditions, plate thickness, and plate temperature. The finite element simulation matrix was developed using a statistical design of experiments (DOE) technique. The Eulerian hydrocode CTH was used to develop the pressure histories that were input into the finite element code Abaqus/Explicit, which implemented the Mississippi State University internal state variable (ISV) plasticity-damage model (DMG). The DMG model is based on the Bammann-Chiesa-Johnson (BCJ) ISV plasticity formulation with the addition of porosity and the void nucleation, growth, and coalescence rate equations that admit heterogeneous microstructures. Material type and thickness were the primary influences on the strain energy at failure, and the materials studied, magnesium and aluminum, showed two different failure mechanisms, tearing at the boundaries and spalling, respectively.
3

Critérios diagnósticos de síndrome metabólica como fator de risco para Diabetes melito gestacional e hiperglicemia gestacional leve estudo de validação diagnóstica e prevalência na gestação /

Vernini, Joice Monaliza. January 2018 (has links)
Orientador: Iracema de Mattos Paranhos Calderon / Resumo: INTRODUÇÃO – Síndrome Metabólica (SM) está associada a gestações complicadas por Hiperglicemia Gestacional Leve (HGL) e Diabetes Melito Gestacional (DMG). OBJETIVO – Avaliar marcadores diagnósticos de SM, definidos por diferentes protocolos, na predição de HGL ou DMG. MÉTODO – Estudo de corte transversal, incluindo 506 mulheres, de gestação única e sem hiperglicemia, avaliadas na idade gestacional (IG) < ou ≥ 24 semanas, e submetidas a TOTG-75g e perfil glicêmico (PG) entre 24 e 28 semanas. Foram obtidos dados clínicos, antropométricos e laboratoriais – glicose de jejum (GJ), hemoglobina glicada (HbA1c), insulina basal e perfil lipídico. Os marcadores diagnósticos de SM, referenciados em três protocolos, foram relacionados a HGL ou DMG, por análises de regressão logística (OR e IC95%) e desempenho preditivo (Sensibilidade e Especificidade), p< 0,05. RESULTADOS – Dos protocolos de SM avaliados, TG ≥ 150 mg/dL, PA ≥ 130 / 85 mmHg, GJ ≥ 100 mg/dL e CC > 88 cm foram FR independentes para HGL ou DMG. Pela análise de desempenho, novos limites foram identificados – na IG < 24 sem, IMC pré ≥ 25 kg/m2 (72,7/50,6%) e CC ≥ 88 cm (78,1/43,9%); na IG ≥ 24 sem, TG ≥ 125 mg/dL (97,7/17,8%) e IMC ≥ 25 Kg/m2 (81,4/45,0%) apresentaram o melhor balanço Sens/Esp. CONCLUSÃO – Este estudo definiu marcadores diagnósticos de SM como preditores de risco independentes, mas novos limites testados tiveram melhor desempenho na predição de HGL ou DMG. Estes resultados deverão auxiliar na instituição de me... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: BACKGROUND – Metabolic Syndrome (MS) has been associated with Mild Gestational Hyperglycemia (MGH) and Gestational Diabetes Mellitus (GDM). OBJECTIVE - To assess the role of MS diagnostic markers proposed in three different sets of guidelines in the prediction of hyperglycemia (MGH or GDM) in pregnancy. METHODS – This cross-sectional cohort study undertaken between March/2014-December/2016, included women with a singleton pregnancy and no hyperglycemia at gestational age (GA) <or ≥ 24 weeks, who underwent a 75g-Oral Glucose Tolerance Test (75g-OGTT) and Glucose Profile ( GP) testing at 24-28 weeks. Clinical, anthropometric and laboratory data (fasting glucose-FG, glycated hemoglobin-HbA1c, basal insulin and lipid profile) were obtained. The relationship between MS markers and risk of MGH or GDM was evaluated by logistic regression analysis (OR, 95% CI). MS markers predictive performance (Sensitivity and Specificity) was also assessed (p <0.05). RESULTS - TG ≥ 150 mg/dL, BP ≥ 130/85 mmHg, FG ≥ 100 mg/dL and WC> 88 cm were identified as independent risk factors for MGH and GDM. Performance analysis identified new limits. Pregestational BMI≥25 kg/m2 (72.7/50.6%) and WC≥88 cm (78.1/43.9%) at GA<24 weeks; and TG≥125 mg/dL (97.7/17.8%) and BMI≥25 kg/m2 (81.4/45.0%) at GA≥24 weeks showed optimal Sensitivity/Specificity balance. CONCLUSION – MS diagnositic markers can independently predict risk, but new different thresholds showed better performance in predicting MGH and GDM. These r... (Complete abstract click electronic access below) / Doutor
4

Ocorrência de hipertensão arterial em mulheres com passado de distúrbios hiperglicêmicos na gestação

Gonçalves, Luciana Colnago [UNESP] January 2003 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:27:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2003Bitstream added on 2014-06-13T18:48:03Z : No. of bitstreams: 1 goncalves_lc_me_botfm.pdf: 549878 bytes, checksum: e39f24a75a657abf0621e0b892311a25 (MD5) / Está estabelecida a associação entre diabetes mellitus (DM) tipo 2 e hipertensão arterial sistêmica (HAS). É conhecida a maior ocorrência de distúrbios hipertensivos no diabetes mellitus gestacional (DMG). No Serviço de Obstetrícia da Faculdade de Medicina de Botucatu, as gestantes são avaliadas quanto ao metabolismo da glicose por meio do teste oral de tolerância à glicose (TOTG) e o perfil glicêmico (PG), sendo classificadas em 4 grupos: IA – com ambos os testes normais, têm tolerância à glicose normal; IB – com apenas o PG alterado, têm hiperglicemia diária; IIA – com apenas o TOTG alterado, têm DMG; IIB – com ambos os testes alterados, têm DMG e hiperglicemia diária. Anteriormente, observamos maior risco de desenvolvimento de DM tipo 2 nos três grupos com distúrbios hiperglicêmicos em relação ao grupo IA. O objetivo deste estudo foi avaliar a freqüência de ocorrência de HAS nos quatro grupos gestacionais após três a 12 anos do parto. De 3113 gestantes acompanhadas pelo Serviço de Obstetrícia, foram selecionadas 551 por meio de processo aleatório e proporcional ao número de gestantes de cada grupo. Destas, puderam participar do estudo 535, assim distribuídas nos grupos: IA - 250 (100,0%); IB - 120 (100,0%); IIA - 77 (87,5%) e IIB - 88 (94,6%). As participantes eram avaliadas clinicamente e quanto à tolerância à glicose, com medição da glicemia de jejum e realização do TOTG quando a glicemia estava alterada (110 a 125 mg/dL). O estudo da associação entre a freqüência de ocorrência das variáveis e os grupos gestacionais foi feito pelo teste de Goodman. Para as variáveis quantitativas, utilizou-se a análise de variância não paramétrica na comparação entre os quatro grupos. Na análise da associação entre a pressão arterial atual e as variáveis... / High blood pressure is associated with type 2 diabetes mellitus (T2DM). There is an increased prevalence of hypertensive disorders in gestational diabetes mellitus (GDM). Glucose intolerance is evaluated at the Obstetrics Unit of Botucatu School of Medicine using the oral glucose tolerance test (OGTT) and glucose profile (GP). Pregnant women are classified into 4 groups: IA, both tests are normal - they have normal glucose tolerance; IB, only the GP is abnormal - they have habitual gestational hyperglycemia; IIA, only the OGTT is abnormal - they have GDM; and IIB, both tests are abnormal - they have GDM and habitual gestational hyperglycemia. Previously, we have observed higher risk of developing T2DM in the 3 above groups with hyperglycemic disorders in relation to the IA group. The aim of this study was to compare hypertension frequency in women among the 4 groups of glucose tolerance, 3 to 12 years after index-pregnancy. From 3,113 pregnant women followed at our Obstetrics Unit, we selected 551 by a process that was randomized and proportional to the number of pregnant women in each group. Of these, 535 could participate in this study and were distributed into the following groups: 250 (100.0%) – IA, 120 (100.0%) – IB, 77 (87.5%) – IIA, and 88 (94.6%) – IIB. The women were evaluated clinically and in relation to glucose tolerance. This was done by measuring fasting plasma glucose and performing the OGTT when plasma glucose was between 110 and 125 mg/dL. Analysis of association between frequency of the variables and the 4 groups was by Goodman’s test. Comparison between the groups in relation to quantitative variables was performed by the non-parametric analysis of variance. The c2 test analyzed the association between normal or high... (Complete abstract click electronic address below)
5

The interactive effects of selected emulsifiers, enzymes, and a carbohydrate based fat substitute in a low fat muffin

Mason, Pamela S. 18 September 2008 (has links)
Selected emulsifiers, enzymes, and a fat substitute were incorporated into a standard muffin recipe, and their effects were compared to a full fat counterpart. Physical and sensory data were reported at the 0.01 significance level. Physical tests indicated no significant differences (p>0.01) among crust “L” and “b” values, specific gravity, water activity, and staling rate after 48 hours storage. The control muffin had a significantly (p<0.01) more yellow crumb, was significantly (p<0.01) less firm, and contained less moisture (p<0.01). The versions containing SSL and DATEM were less firm (p<0.01) and retained slightly more moisture (p<0.01) than the other reduced fat muffins. The control muffins and the versions containing SSL and DATEM were significantly (p<0.01) greater in volume than the other reduced fat muffins. Fat and DATEM were found to prolong retrogradation at a significantly (p<0.01) slower rate than in the other versions after 24 hours storage. Sensory results indicated no significant differences (p>0.01) in perceived adhesiveness. The muffins containing only the fat substitute and enzymes were rated with a significantly (p<0.01) darker crust color and (p<0.01) aftertaste than the other versions. The control muffin was significantly (p<0.01) moister, and contained a larger crumb (p<0.01) than the other versions. The control muffin was significantly (p<0.01) less cohesive. The results obtained from the data indicated that there were similarities and differences between the reduced fat versions and the control. / Master of Science
6

Technologies and Evaluation Metrics for On-Board Over the Air Control

Datta, Aneysha January 2022 (has links)
This project has been carried out at the Electronic Embedded Systems Architecture Department at Volvo Construction Equipment (VCE), Eskilstuna, Sweden. It forms the baseline for a stepwise systematic research initiative to convert wired technologies used for certain in-vehicle control and communication components to wireless technologies. In-vehicle wireless networks are being increasingly improvised and researched to minimize the manufacturing and maintenance cost of the total amount of wiring harnesses within the vehicles. Fault tracking and maintenance becomes convenient within a wireless network. Wireless intra-vehicular communication provides an open architecture that can accommodate new components and applications. One such usability has been studied in this thesis for the Display Control Unit of Volvo paver machines. A newly designed hardware demands new technologies to ensure operator safety, security, comfort, convenience, and information. The research conducted in this thesis takes into account five probable use-cases in terms of control and communication around the new hardware, and studies suitable wireless technologies that could replace the wired technology that will be used. From a detailed literature study and the specifications provided by VCE, WAVE/IEEE802.11p and DMG/IEEE 802.11ad have been selected as optimal candidates. These two have been modelled at the physical layer of the system. After comparing the results of WAVE for 4 different channel models and 8 different coding and modulation schemes, it has been found that 1/2BPSK(3 Mbps) and 1/2 QPSK(6 Mbps) are optimal for the 3 Rician Fading Channels of Rural LOS, Urban LOS, and Highway LOS. For use-cases that involve larger distances and a large exchange of control signals, WAVE is a good choice. DMG has 19 modulation schemes for Single Carrier Modes and some of them are extremely robust at low SNR. Around SNR 20, it shows lesser packet errors than WAVE. The lower error rate is also evident from the BER values. For use-cases that involve smaller distances and a lot of image data, DMG is preferable. The work, however, does not study the safety and security aspects. Thean alysis and modelling are theoretical being based on literature studies and the necessary parameters provided by VCE. The model needs to be evaluated against field studies and practical measurements with a prototype before implementation inside the paver.
7

Late Pleistocene deglaciation histories in the central Mérida Andes (Venezuela) / Histoires de déglaciation pendant le Pléistocène Supérieur dans les Andes centrales de Mérida (Venezuela)

Angel Ceballos, Isandra Fortuna 12 February 2016 (has links)
Les Andes de Mérida (Venezuela) est caractérisé par la présence de morphologie glaciaire bien préservée entre 2400-4978 m. Les études de ces morphologies glaciares font la contribution pour mieux comprendre et reconstruire la Dernière Glaciation aux Andes Vénézuéliennes. La reconstruction de la Dernière Glaciation (connue dans la région comme Glaciation Mérida) était limitée par la disponibilité de chronologie glaciaire. Cette thèse fait sa contribution à la reconstruction de la Dernière Glaciation et à la connaissance du paléoclimat depuis le Pléistocène Superieur. La méthodologie a involucré l´analyse géomorphologique et l´étude géochronologique. La morphologie glaciaire a été datée avec la technique de nucléides cosmogéniques produits in-situ (10Be). Cette technique est appropriée pour dater les matériels riches en quartz et la période d´intérêt. Les inférences des conditions paleoclimatiques ont été faites sur la base des analyses de la paléo ELA.Des différentes dynamiques glaciares ont été identifiées aux Andes centrales de Mérida. Dans les vallées de Mucubají et Mucuchache, la dynamique a été caractérisée par plusieurs étapes de avancé-arrêt des glaciaires dans un recul général de la glace. Dans les vallées de Gavidia et Mifafí, la disparition des glaciares a été très rapide avec la vitesse de recul plus haute (entre 4-7 km/ky). Divers caractéristiques morpho métriques comme la pente du fond de la vallée, la topographie de la zone d´accumulation (cirques glaciares avec les murs très incliné), des surfaces de la zone d´accumulation et son orientation ont aussi contrôlé les différents dynamiques glaciares.Les avancées des glaciares ont été identifiées entre 2500-4200 m. Les avancées glaciares pendant le MIS 3 ont été reconnues à Sierra Nevada. Ces avancées ont été liées aux hautes précipitations dans le nord de l´Amérique de Sud produites par l´activité de la Zone de Convergence Intertropical. Ces avancées ont été aussi reliées aux conditions plus chaudes et humides dans l´Hémisphère Nord (aussi ces conditions ont été identifiées aux Andes vénézuéliennes et sont connues comme l´Interstadío El Pedregal). Les avancées glaciares pendant le Dernière Maximum Glaciares ont été enregistrées en Sierra Nevada á Mucubají et Las Tapias entre 3100-3600 m. Principalement, les avancées glaciares MIS 2 sont arrivées pendant l´Oldest Dryas-El Caballo Estadío à 17 ka. Ces avancées glaciares ont été reliées aux températures froides dans l´Hémisphère Nord et les températures plus froides enregistrées dans les carottes de glaciares tropicaux.Mots clésDatation par cosmogéniques produits in-situ, morphologie glaciaire, Pléistocène, Dernière Glaciation, LGM, paléo ELA. / The central Mérida Andes (Venezuela) landscape is characterized by the presence of well-preserved glacial landforms located between 2400 and 4978 m a.s.l. Geomorphological studies of these glacial landforms significantly contribute to the Venezuelan Andes glaciations reconstructions. However, Last Glaciation (locally called Mérida Glaciation) was poorly reconstructed because of limited chronological data. This dissertation attempts to contribute to the Last Glaciation reconstruction and paleoclimate knowledge since the late Pleistocene. Accordance this necessity, the methodology involved geomorphological analysis and geochronological study. Glacial landforms were dated based on the Terrestrial Cosmogenic Nuclide dating (10Be). This method is suitable for date quartz-rich materials and for the period of interest. To deduce paleoclimate conditions an analysis based on paleo ELA was developed.In the central Mérida Andes different Late Pleistocene glacier dynamics were identified. In the Mucubají and the Mucuchache valleys, successive stages of glacier stop-advance were identified during an overall glacier withdrawal. In the Gavidia and Mifafí valleys, glacier withdrawal was rapid with the highest retreat rates (between 4-7 km/ky). Morphometric features as glaciers bottom valley slopes, accumulation zone topography (glaciers cirques with steep walls), areas and orientation controlled different glaciers dynamics.Glacier advances were evidenced between 2500-4200 m. MIS 3 glaciers advances has been recognized in the Sierra Nevada. These were related to the highest runoff in the north of South America produced by the Intertropical Convergence Zone (ITCZ) and the local warm and wet climate conditions (locally named El Pedregal Interstadial). LGM glacier advances were recorded in Sierra Nevada in the Mucubají and Las Tapias between 3100-3600 m. MIS 2 Glaciers advances mainly occurred during the Oldest Dryas- El Caballo Stadial at around 17 ka. These glaciers advances correlate to the cold temperatures in the North Hemisphere and the coldest temperatures recorded in tropical ice cores.KeywordsTerrestrial cosmogenic nuclides dating, TCN, cosmogenic dating, glacial landforms, Andes Mérida, Venezuela. Pleistocene, Last Glaciation, LGM, paleo ELA, tropic paleoclimate.
8

三甲基甘胺酸和二甲基甘胺酸改善甲基安非他命所導致神經行為毒性 / N,N,N-Trimethylglycine and N,N-Dimethylglycine improve methamphetamine-induced neurobehavioral toxicity

陳映安 Unknown Date (has links)
甲基安非他命是一種被廣泛濫用的非法神經興奮劑,而且使用之後常伴隨著精神疾病的發生,動物研究也顯示,施打甲基安非他命所引起的神經毒性不僅會造成多巴胺神經元及血清素神經元的損傷,也引起認知功能和社交行為的缺失,同時對於產生迷幻作用的5-HT2A受體作用劑的行為反應增強。N,N,N-trimethylglycine (TMG)和N,N-dimethylglycine (DMG)是甘胺酸的甲基化衍生物,由於這兩種藥物具有治療神經系統疾病的潛力,因此本研究的目的為評估TMG及DMG是否可以預防或改善小鼠在甲基安非他命的暴露下所導致的行為缺失包括新位置辨識測試,新物體辨識測試,社交行為互動測試以及使用5-HT2A受體作用劑DOI 誘導小鼠頭部抽搐(head twitch )的行為。實驗方式為腹腔注射給予雄性ICR小鼠甲基安非他命,一天注射四劑(4 × 5mg/kg),每劑間隔兩小時。實驗一,小鼠在暴露甲基安非他命,先確認行為改變後,給予腹腔注射TMG及DMG (10或30 mg/kg)連續七天,評估TMG及DMG的治療效果。實驗二在施打每劑甲基安非他命30分鐘前給予TMG及DMG (100 mg/kg),七天後進行行為評估,實驗三,評估TMG及DMG個別及混合劑量的治療效果,小鼠給予甲基安非他命之後,先確認行為改變,再給予腹腔注射TMG及DMG (20、5+5或是10+10 mg/kg) 連續七天,七天後進行行為測試。實驗四,檢測TMG及DMG的治療效果是否藉由活化NMDA受體glycine binding site,小鼠給予甲基安非他命七天之後,腹腔注射TMG及DMG (20 mg/kg)並在給予TMG及DMG前30分鐘給予glycine binding site 拮抗劑7-chlorokynurenic acid (7-CK) (1 mg/kg),連續給藥七天,七天後進行行為評估。實驗結果發現連續給予七天TMG及DMG在個別劑量及混合劑量中都能夠恢復甲基安非他命所造成的認知功能缺損,社交退縮和降低由DOI 誘導小鼠頭部抽搐行為表現,以及在紋狀體中酪氨酸羥化酶的蛋白質表達減少情況。而前給予7-CK則阻斷TMG及DMG對甲基安非他命所造成的認知功能缺損,社交退縮的改善作用,但是對TMG及DMG對DOI 誘導小鼠頭部抽搐的行為的改善作用影響較小,顯示TMG及DMG可能都是經由活化NMDA 受體的glycine binding site改善甲基安非他命所造成的認知功能缺損,社交退縮,這些發現表示,TMG及DMG具有治療甲基安非他命成癮者所造成的精神分裂等異常症狀的潛力。 / Methamphetamine (METH) is a widely abused illicit psychostimulant. METH use is commonly associated with psychosis. A neurotoxic regimen of METH, which damages the dopaminergic and serotonergic neurons, causes cognitive dysfunction, social interaction deficits, and supersensitivity to hallucinogen in mice. N,N,N-trimethylglycine (TMG) and N,N-dimethylglycine (DMG) are methyl derivatives of amino acid glycine and naturally occur as intermediate metabolites in choline-to-glycine metabolism. Growing evidence shows that both compounds have potential to treat some neurological disorders. The aim of this study was to examine the protective and therapeutic effects of TMG and DMG on METH-induced behavioral aberrations. The novel location recognition test (NLRT), the novel objective recognition test (NORT), the social interaction and the hallucinogenic 2, 5-dimethoxy-4-iodoamphetamine (DOI)-induced head twitch response were evaluated. Male ICR mice received one day drug treatment with four injections of METH (4 × 5 mg/kg, i.p.) or saline at 2h interval. First, TMG or DMG (10 or 30 mg/kg, i.p.) were separately administered once daily for seven consecutive days after the behavioral impairment was confirmed in METH-treated mice. Seven days after final injection of TMG and DMG, the behavioral tests were monitored. Secondly, the preveting effects of TMG and DMG were examined by TMG and DMG (100 mg/kg, i.p.) pretreatment, 30 min prior to each dose of METH. Third, the lower dose (20 mg/kg) and combined effects of TMG and DMG (5+5 or 10+10 mg/kg i.p.) were evaluated. Fourth, in order to determine if the improving effects of TMG and DMG are mediated by NMDA receptor glycine binding site, the glycine binding site antagonist 7-CK (1 mg/kg, i.p.) was administered 30 min prior to each dose of TMG and DMG (20 mg/kg, i.p.), TMG and DMG dose-dependently improved, but not prevented the METH-induced cognition deficits, social withdrawal and hypersensitivity to hallucinogen with additional effect. Pretreatment of 7-CK, reversed the improving effects of TMG and DMG on behavioral deficits after METH exposure, yet had minor effect on hypersensitivity to hallucinogen. These results demonstrate that TMG and DMG might activate the glycine binding site of NMDA receptor to improve METH-induced cognition deficits and social withdrawal. TMG and DMG may be the novel therapeutic agents for psychiatric disorders related to METH abuse.

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