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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.
11

Modelamiento hidrogeologico para estimar el caudal optimo de la parte baja del acuifero del valle del rio Lurín

Díaz Jara, Paul Jhonatan January 2015 (has links)
La parte baja del Acuífero del Valle del Río Lurín, el cual comprende los distritos de Lurín, Pachacamac y Cieneguilla, desde hace años viene sufriendo un déficit en sus reservas de aguas subterráneas, este problema se ha ido agravando durante el tiempo por el incremento no contralado de nuevos pozos, y la extracción no contralada de sus reservas de aguas subterráneas, la siguiente tesis trata de representar el comportamiento del Acuífero con la elaboración del modelo Matemático Visual ModFlow, con la finalidad de recomendar el caudal apropiado para evitar el descenso de la napa freática
12

Distribución del agua en el Perú desde una perspectiva de cuenca

Sabogal, Ana 10 April 2018 (has links)
El artículo plantea la importancia de integrar el concepto de cuenca a la distribución de los recursos. Se propone integrar un trabajo detallado por cuenca que involucre el cálculo del caudal de agua, la variación de la napa freática, el caudal ecológico, los volúmenes de erosión y la distribución actual del agua, para de allí plantear la distribución del agua en la cuenca. El aprovechamiento y distribución de los recursos naturales se encuentran estrechamente vinculados a la distribución del agua. Una inadecuada distribución del agua orientada solo a satisfacer el aprovechamiento de los recursos, sin tener en cuenta los ciclos ecológicos para su reposición, puede destrozar los ecosistemas existentes.El conjunto de cuencas, como unidades geográficas, deben contribuir a una gestión de recursos que permita una adecuada distribución del agua y potencie cada región, integrándola a un sistema de distribución de oportunidades, riqueza y producción en el contexto del país.
13

Characteristics of excitatory synapses and mutant huntingtin distribution in the Q175 mouse model of Huntington’s disease

Chen, Dickson Tik Sang 10 November 2021 (has links)
Huntington’s disease is an inherited neurodegenerative disease characterized by the degeneration of the cerebral cortex, thalamus, and striatum. The loss of neurons in the cerebral cortex and the thalamus may affect the synaptic circuitry in the striatum as these regions send glutamatergic projections (corticospinal & thalamostriatal) to neurons in the striatum. Prior studies have suggested the detrimental impact that the mutant Huntingtin protein (mHTT) may have on corticostriatal afferents, but less is known thalamic inputs to the dorsal striatum. In this study, we report a 50% reduction in thalamostriatal axospinous synapse density and significant reductions in dendritic spine volume at the ultrastructural level using electron microscopy. Additionally, dystrophic alterations to mitochondria size and morphology were also found. At the microcircuit level, we report a reduction in the spatial abundance of thalamostriatal axon terminals at the rostral, middle, and caudal levels of the dorsolateral striatum while an inverse distribution was observed for mHTT, suggesting a novel topographic distribution of thalamostriatal projections and mHTT along the rostral-caudal axis of the dorsolateral striatum. These findings are novel in the Q175 HD mouse model and supports the theory of an excitatory: inhibitory imbalance contributing to structural synaptic changes in the dorsal striatum. Further studies of the corticostriatal projections will determine the global extent of this imbalance.
14

Medición de caudales máximos en los ríos Chancay y Piura y, su influencia en el dimensionamiento de estructuras hidráulicas

Callañaupa Tocto, Omar Alejandro 02 October 2019 (has links)
El presente trabajo busca mostrar la diferencia entre el caudal máximo diario anual y el caudal anual máximo instantáneo. Esto, porque el primero es el dato que se obtiene en la mayoría de estaciones de medición de caudal en todo el país y el segundo es el que se obtiene mediante estructuras hidráulicas que permiten medir el caudal en todo momento evitando el efecto de la socavación que genera el agua al escurrir por terrenos naturales proclives a esta. Se demostrará porque estos datos se deben considerar en la determinación de los caudales de diseño extremos de las estructuras hidráulicas. Se analizará y comparará ambos resultados y se explicará el por qué es importante trabajar con el caudal instantáneo en vez del máximo medio diario anual. Se justificará por qué a pesar de que el caudal anual máximo instantáneo es mucho más difícil de obtener, a largo plazo resulta más provechoso de utilizar. Se expondrá por qué el registro de caudal máximo diario anual el que tienen a disposición los ingenieros en la gran mayoría de ríos del litoral de nuestro país. Se demostrará que la diferencia entre ambos genera un error que representa un verdadero riesgo para el diseñador de infraestructura hídrica que basa sus cálculos en un registro que podría resultar peligroso pues puede estar subestimado. / This work seeks to show the difference between the annual maximum daily flow and the instantaneous maximum annual flow. This is because the first is the data obtained in most of the flow measurement stations throughout the country and the second is obtained by measurements of hydraulic structures that allow the flow to be measured at all times avoiding the effect of the undermining that generates water by draining through natural lands. It will be demonstrated why these data should be considered in determining the extreme design flow rates of hydraulic structures. Both results will be analyzed and compared and it will be explained why it is important to work with the instantaneous flow rate instead of the maximum annual average daily. It will be justified why although the maximum instantaneous annual flow is much more difficult to obtain, in the long term it is more profitable to use. It will be explained why the annual maximum daily flow record available to engineers in the vast majority of rivers along the coast of our country. It will be shown that the difference between the two generates an error that represents a real risk for the water infrastructure designer who bases his calculations on a record that could be dangerous and it may be underestimated. / Tesis
15

Generation of thalamic neurons from mouse embryonic stem cells / マウス胚性幹細胞からの視床神経の分化誘導

Shiraishi, Atsushi 23 January 2018 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20790号 / 医博第4290号 / 新制||医||1025(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 高橋 淳, 教授 井上 治久, 教授 林 康紀 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM
16

No limiar da auto-mutilação: fatores ecológicos e morfológicos envolvidos na autotomia caudal em Tropidurus itambere (Rodrigues, 1987) (Sauria:Tropiduridae)

Amorim, Joana de Dornellas Cysneiros Gomes de 27 February 2013 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-04-04T15:04:20Z No. of bitstreams: 1 joanadedornellascysneirosgomesdeamorim.pdf: 1811388 bytes, checksum: 09763f5f5602a497decd667655eb0c68 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-04-24T03:56:58Z (GMT) No. of bitstreams: 1 joanadedornellascysneirosgomesdeamorim.pdf: 1811388 bytes, checksum: 09763f5f5602a497decd667655eb0c68 (MD5) / Made available in DSpace on 2016-04-24T03:56:58Z (GMT). No. of bitstreams: 1 joanadedornellascysneirosgomesdeamorim.pdf: 1811388 bytes, checksum: 09763f5f5602a497decd667655eb0c68 (MD5) Previous issue date: 2013-02-27 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A autotomia caudal é uma resposta anti-predação voluntária amplamente empregada por lagartos. Suas consequências estão bem descritas na literatura, mas os fatores envolvidos na sua ocorrência carecem de aprofundamento. Pretendeu-se então averiguar se há diferença tanto na propensão à autotomia quanto no padrão de crescimento corporal e caudal de indivíduos com tamanho corporal diferente durante as estações quente/chuvosa (verão tropical) e fria/seca (inverno tropical). Para tanto foram mantidos em terrários externos três grupos experimentais (n = 19) de massas corpóreas diferentes (P1, P2 e P3), cujas caudas foram autotomizadas por constrição mecânica, medindo-se a pressão exercida e o tempo até a soltura da cauda. Dados morfométricos foram aferidos semanalmente e avaliados usando o test T bicaudal para amostras não pareadas, comparando-se as variáveis em função do peso corporal. As porções caudais liberadas foram conservadas em álcool e dissecadas, assim como quatro lagartos que morreram ao longo dos experimentos. A anatomia caudal foi analisada e comparada com descrições existentes. Elaborou-se um modelo tridimensional passível de ser usado como ferramenta didática e analítica. Foram encontradas em média 32 vértebras caudais em T. itambere. A maioria dos parâmetros avaliados não apresentou significância estatística, devido ao pequeno número amostral, mas tendências e possibilidades são apresentadas e discutidas em vista da literatura atual. Foi significativa a relação inversa entre temperatura cloacal e tempo até a autotomia. / Autotomy is an anti-predator behavior widely employed by lizards. The energetic consequences of this process are vastly describe in literature, yet the details involved in it’s occurrence lack thoroughness. This study intent to evaluate if there are differences related to body weight in propensity to realize autotomy, in body and caudal growth, both during the hot/wet season (tropical summer) and the cold/dry season (tropical winter). To accomplish that three groups of lizards (n = 19) with different body mass (P1, P2 and P3) were kept in out-doors cages during cold (July to September 2012) and hot seasons (November 2012 to January 2013). Autotomy was induced by constriction of the tail, while measuring the pression applie to it’s surface as well as the time until it’s release. Morphometric data was assessed weekly and processed using two-tailed t-test for unpaired samples, comparing variables according to body weight. The released portion of the tail was preserved in alcohol and dissected, as were the four lizards that happened to die during the experimental process. Caudal anatomy was analyzed and compare with preexisting descriptions. A three-dimensional model with didactic and analytic potential was elaborated. We found an average of 32 caudal vertebraes in T. itambere. Most of the analyzed parameters did not present statistical significance, due to the small sample size. However we present and discuss every tendency and possibility in face of the current literature. We did found a significant inverse relation between cloacal temperature and the time subjects took to undergo autotomy.
17

The role of flexibility on propulsive performance of flapping fins

Kancharala, Ashok Kumar 02 September 2015 (has links)
The versatility of the fish to adapt to diverse swimming requirements has attracted the attention of researchers in studying bioinspired propulsion for developing efficient underwater robotics. The tail/caudal fin is a major source of thrust generation and is believed that the fish modulates its fin stiffness to optimize the propulsive performance. Inspired by the stiffness modulation of fish fins, the objective of this research is to predict and evaluate the effect of flexibility on propulsive performance of flapping fins. The stiffness of the fins vary along their length and optimization studies have been performed to predict the stiffness profiles that maximize performance. Experiments performed on the real fish caudal fins to measure the stiffness variation along their length validate the theoretical optimal stiffness profiles and provide an insight about the evolution of fish fins for optimal performance. Along with the fin stiffness, the stiffness of the joint (caudal peduncle) connecting the fish body to the tail plays a major role in the generation of thrust. The numerical and experimental investigation has shown that there exists an optimal combination of fin and joint stiffness for each operating condition, thus providing the motivation for active stiffness control during locomotion to optimize efficiency. Inspired by nature's ability to modulate stiffness and shape for different operating conditions, an investigation has been carried out on active control of flapping foils for thrust tailoring using Macro Fiber Composites (MFCs). It has been observed that the performance can be enhanced by controlling the deformation, and distributed actuation along fin produces maximum performance through proper selection of the phase difference between heaving and voltage. Flapping fins produce forces which are oscillatory in nature causing center of mass (COM) oscillations of the attached bodies posing problems of control and maneuverability. Optimization studies have revealed that flexibility of the fin plays a major role in reducing the COM oscillations along with the other operating parameters. Based on these studies, the design principles and guidelines that control the performance have been proposed which aid in the development of aerial and underwater robotic vehicles. Additionally, these studies provide some insight in to how fish might modulate its stiffness based on the requirements. / Ph. D.
18

Efeito da bupivacaína racêmica e da mistura enantiomérica de bupivacaína associadas ou não com a clonidina, para anestesia caudal em crianças / Effect of racemic bupivacaine and enantiomeric mixture of bupivacaine associated or not with clonidine on caudal anesthesia in children

Valinétti, Emilia Aparecida 31 May 2005 (has links)
Este é um estudo clínico, prospectivo, aleatório, e duplamente encoberto realizado em 40 crianças submetidas a cirurgia infra-umbilical de pequeno porte, sob anestesia epidural sacra realizada com a mistura enantiomérica de bupivacaína (S75R25) comparada com a bupivacaína racêmica (SR50) isoladas ou em associação com a clonidina. O objetivo foi avaliar a duração do bloqueio motor e sensitivo, o consumo de sevoflurano e as variações da pressão arterial sistólica (PAS) e freqüência cardíaca (FC). O bloqueio motor foi avaliado pela escala de Bromage, durante o período de oito horas de observação no pós-operatório. A analgesia foi avaliada pelos escores obtidos com escala objetiva para análise da dor e a duração da analgesia foi considerada como o tempo entre a administração do anestésico local no espaço epidural sacro e a primeira dose de analgésico administrado. Os resultados obtidos foram submetidos à análise estatística onde p< 0,05 foi considerado significante. Os resultados mostraram que houve aumento significativo do bloqueio motor somente na primeira hora quando a bupivacaína SR50 foi associada a clonidina, mas não ocorreu o mesmo com a bupivacaína S75R25. Em relação a analgesia não houve diferença significante entre a bupivacaína SR50 e a bupivacaína S75R25 associadas ou não à clonidina. Não houve diferença significativa no consumo de sevoflurano entre os grupos estudados quando a clonidina foi associada aos anestésicos. Os valores da PAS e FC no pós-operatório, nos grupos onde a clonidina foi associada com ambos anestésicos locais, foram inferiores em todos os momentos de avaliação, porém sem significância estatística / This is a prospective, randomized double-blind clinical trial performed in 40 children using an enantiomeric mixture of bupivacaine (S75R25) compared to racemic bupivacaine SR50 plain or associated with clonidine, to caudal blockade. The aim of this study was to investigate the motor and sensitive block, sevoflurane requirement, blood pressure (PAS) and heart rate (FC) in children scheduled to sub-umbelical surgeries. The motor block was evaluated by Bromage scale for eight hours during the postoperative period. The analgesia was evaluated postoperatively for eight hours by an objective pain scale and the analgesia duration was taken as the time between the local anesthetic administration into epidural space and the first analgesic rescue. The results obtained were submitted to statistical analysis test where p< 0,05 was considered significant. There was a significant increase in the motor block at first hour on postoperative period when bupivacaine SR50 was associated to clonidine, but it did not occurr with the enantiomeric mixture of bupivacaine S75R25. There was no difference between bupivacaine SR50 and bupivacaine S75R25 associated or not to clonidine regarding to analgesia duration. There was no difference in the requirement of sevoflurane between groups in spite of the clonidine admixture to the local anesthetics. There was an absolut decrease in the PAS and FC values on the postoperative evaluation, but it was not statistically significant
19

Efeito da bupivacaína racêmica e da mistura enantiomérica de bupivacaína associadas ou não com a clonidina, para anestesia caudal em crianças / Effect of racemic bupivacaine and enantiomeric mixture of bupivacaine associated or not with clonidine on caudal anesthesia in children

Emilia Aparecida Valinétti 31 May 2005 (has links)
Este é um estudo clínico, prospectivo, aleatório, e duplamente encoberto realizado em 40 crianças submetidas a cirurgia infra-umbilical de pequeno porte, sob anestesia epidural sacra realizada com a mistura enantiomérica de bupivacaína (S75R25) comparada com a bupivacaína racêmica (SR50) isoladas ou em associação com a clonidina. O objetivo foi avaliar a duração do bloqueio motor e sensitivo, o consumo de sevoflurano e as variações da pressão arterial sistólica (PAS) e freqüência cardíaca (FC). O bloqueio motor foi avaliado pela escala de Bromage, durante o período de oito horas de observação no pós-operatório. A analgesia foi avaliada pelos escores obtidos com escala objetiva para análise da dor e a duração da analgesia foi considerada como o tempo entre a administração do anestésico local no espaço epidural sacro e a primeira dose de analgésico administrado. Os resultados obtidos foram submetidos à análise estatística onde p< 0,05 foi considerado significante. Os resultados mostraram que houve aumento significativo do bloqueio motor somente na primeira hora quando a bupivacaína SR50 foi associada a clonidina, mas não ocorreu o mesmo com a bupivacaína S75R25. Em relação a analgesia não houve diferença significante entre a bupivacaína SR50 e a bupivacaína S75R25 associadas ou não à clonidina. Não houve diferença significativa no consumo de sevoflurano entre os grupos estudados quando a clonidina foi associada aos anestésicos. Os valores da PAS e FC no pós-operatório, nos grupos onde a clonidina foi associada com ambos anestésicos locais, foram inferiores em todos os momentos de avaliação, porém sem significância estatística / This is a prospective, randomized double-blind clinical trial performed in 40 children using an enantiomeric mixture of bupivacaine (S75R25) compared to racemic bupivacaine SR50 plain or associated with clonidine, to caudal blockade. The aim of this study was to investigate the motor and sensitive block, sevoflurane requirement, blood pressure (PAS) and heart rate (FC) in children scheduled to sub-umbelical surgeries. The motor block was evaluated by Bromage scale for eight hours during the postoperative period. The analgesia was evaluated postoperatively for eight hours by an objective pain scale and the analgesia duration was taken as the time between the local anesthetic administration into epidural space and the first analgesic rescue. The results obtained were submitted to statistical analysis test where p< 0,05 was considered significant. There was a significant increase in the motor block at first hour on postoperative period when bupivacaine SR50 was associated to clonidine, but it did not occurr with the enantiomeric mixture of bupivacaine S75R25. There was no difference between bupivacaine SR50 and bupivacaine S75R25 associated or not to clonidine regarding to analgesia duration. There was no difference in the requirement of sevoflurane between groups in spite of the clonidine admixture to the local anesthetics. There was an absolut decrease in the PAS and FC values on the postoperative evaluation, but it was not statistically significant
20

Maintenance and elimination of long-term axial progenitors in mouse

Wymeersch, Filip Jos January 2012 (has links)
Elongation of the vertebrate rostrocaudal axis depends on localised populations of axial progenitors. Previous work has demonstrated the presence of Neuromesodermal (NM) progenitors that behave as multipotent stem cells, which contribute to the neurectoderm and mesoderm throughout axis elongation. They have been localised to the Node-­‐Streak Border (NSB) in the primitive streak region, and the Chordoneural Hinge (CNH) in its descendant, the tail bud. At primitive streak stages, the Caudal Lateral Ectoderm (CLE) on either side of the primitive streak itself is also fated for neurectoderm and mesoderm. However, fate mapping studies in mouse and chick have suggested that these progenitors are more transitory than those in the NSB and CNH, leading to the idea that two different types of progenitor cell exist in the primitive streak region; long-­‐term (stem cell-­‐like) and transient progenitors. In this thesis, I have examined the potency of the CLE cells by heterotopically grafting them into the NSB. Anterior CLE cells are exquisitely sensitive to their position and differentiate predominantly as neurectoderm, mesoderm, or both, depending on their exact location in the NSB. Most significantly, their descendants are retained in the CNH, indicating that CLE cells show equal potential to NSB progenitors on transplantation to the border environment. The relationship between fate and potency within the streak stage embryo suggest a mechanism by which stem cells are maintained not only by their intrinsic stem cell program, but are also influenced by their location. Furthermore, I have investigated the expression of candidate markers of NM-­‐progenitors, and have found that the combined expression of Sox2 and T genes in the progenitor area coincides with observed NM-­‐potency, and could serve as a marker for this stem cell population. Over time, axial elongation comes to a halt and NM-­‐progenitors are thereafter not longer active. It is still unclear how exactly this process occurs and specifically whether axial elongation ceases because NM progenitors are eliminated. I have investigated the events occurring immediately before the end of axial elongation. Morphological and gene expression analysis shows that apoptosis reaches a peak only after the complete axis has been laid down, and is not dramatically elevated in the progenitors themselves before that. In order to test signalling pathways that lead to progenitor maintenance, I have developed an in vitro tail growth assay that recapitulates in vivo development, as measured by several morphometric criteria. I show that, even though FGF signalling is critical for most cells in the tail bud including NM-­‐progenitors, it is not sufficient for NM-­‐ progenitor maintenance. In contrast, exposing tail buds to elevated Wnt/β-­‐catenin signalling does prolong the lifetime of NM-­‐progenitors in the ageing tail bud, as judged by the presence of Sox2-­‐T double-­‐positive cells. In this regard we have found that the time of cessation coincides with the disappearance of Sox2-­‐T double-­‐positive cells, the disappearance of Wnt3a and concomitant neuralisation of the progenitor region. This data suggest an important governing role for Wnt signalling in both maintenance and fate decision of NM progenitors. Thus the disappearance of Wnt signalling in the tail bud over time could well be the main reason for triggering the halt of caudal elongation.

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