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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.
221

Stress driven changes in the kinetics of bilayer embedded proteins: a membrane spandex and a voltage-gated sodium channel

Boucher, Pierre-Alexandre January 2011 (has links)
Bilayer embedded proteins are affected by stress. This general affirmation is, in this thesis, embodied by two types of proteins: membrane spandex and voltage-gated sodium channels. In this work, we essentially explore, using methods from physics, the theoretical consequences of ideas drawn from experimental biology. Membrane spandex was postulated to exist and we study the theoretical implications and possible benefits for a cell to have such proteins embedded in its bilayer. There are no specific membrane spandex proteins, rather any protein with a transition involving a large enough area change between two non-conducting states could act as spandex. Bacterial cells have osmovalve channels which open at near-lytic tensions to protect themselves against rupture. Spandex expanding at tensions just below the osmovalves’ opening tension could relieve tension enough as to avoid costly accidental osmovalve opening due to transient bilayer tension excursions. Another possible role for spandex is a tension-damper: spandex could be used to maintain bilayer tension at a fixed level. This would be useful as many bilayer embedded channels are known to be modulated by tension. The Stress/shear experienced in traumatic brain injury cause an immediate (< 2 min) and irreversible TTX-sensitive rise in axonal calcium. In situ, this underlies an untreatable condition, diffuse axonal injury. TTX sensitivity indicates that leaky voltage-gated sodium (Nav) channels mediate the calcium increase. Wang et al. showed that the mammalian adult CNS Nav isoform, Nav1.6, expressed in Xenopus oocytes becomes “leaky” when subjected to bleb-inducing pipette aspiration. This “leaky” condition is caused by a hyperpolarized-shift (left-shift or towards lower potentials, typically 20 mV) of the kinetically coupled processes of activation and inactivation thus effectively degrading a well-confined window conductance into a TTX-sensitive Na leak. We propose experimental protocols to determine whether this left-shift is the result of an all-or-none or graded process and whether persistent Na currents are also left-shifted by trauma. We also use modeling to assess whether left-shifted Nav channel kinetics could lead to Na+ (and hence Ca2+ ) loading of axons and to study saltatory propagation after traumatizing a single node of Ranvier.
222

The Serving and the Served: Relationship between suppliers and food hubs in Swedish Alternative Food Networks

Korcekova, Kristina January 2017 (has links)
The Swedish alternative food networks landscape is underdeveloped compared to that of the US or the countries of Western Europe, however its development has sped up in recent years. The relationship between the farmer and the food hub is the first one to be built when an Alternative Food Network is being set up and therefore represents a valid starting point in the hitherto scarcely studied field of alternative food distribution in Sweden. The paper used a relationship-marketing framework with the addition of elements from Civic Food Networks conceptualization of Alternative Food Networks in order to explain the creation and maintenance, as a well as the quality and depth of supplier-distributor relationships in two cases of Swedish food hubs. Given the immaturity of the Swedish market, this paper tried to explore the possible variations existing in the landscape. In the case of student-led food cooperative Ultimat and its two studied suppliers, values and larger local food systems goals played the primary role in creating and maintaining the relationship, in spite of the poor economic performance of such a relationship in the eyes of the suppliers. The linkages forged between the two entities are strong due to shared values and common goals. In the case of Bygdens Saluhall, the values play a certain role, but the economic element remains crucial for the farmers. At the same time, the connection is closer and ownership of the project by the farmers more significant. Additionally, points of interest arose for future research, notably the diverging stance of Ultimat’s suppliers vs. Bygdens Saluhall’s suppliers in the question of pro-business food hubs and organization of alternative food networks in general.
223

Avaliação de variáveis associadas à redução do número de linfonodos em espécime cirúrgico de câncer de reto após quimiorradioterapia neoadjuvante / Evaluation of variables associated to the reduction in the number of lymph nodes in rectal cancer specimen after neoadjuvant chemoradiotherapy

Leonardo Alfonso Bustamante Lopez 03 May 2017 (has links)
Introdução: De acordo com a União Internacional Contra o Câncer um mínimo de 12 linfonodos (LN) deve ser obtido no espécime cirúrgico para o estadiamento do câncer colorretal (CCR). Estudos recentes reportaram que o uso da quimioirradioterapia neoadjuvante (QRN) pode resultar na não obtenção do número mínimo de LN na peça em 30-52% dos pacientes. Objetivo: Identificar os fatores relacionados à redução do número de LN ressecados em pacientes submetidos à neoadjuvancia e a excisão total do mesorreto. Pacientes e métodos: De janeiro de 2012 a março de 2013, 160 pacientes com câncer de reto foram submetidos à QRN (5-FU e 5040 Gys) seguida de excisão total de mesorreto com ligadura dos vasos mesentéricos inferiores nas suas raízes. Foram incluídos pacientes com estadiamento T3, T4 e/ou N+ que distavam até 10cm da borda anal e T2N0 que distavam até 7 cm da borda anal. Foram excluídos pacientes cujo tratamento com quimiorradioterapia neoadjuvante foi incompleto, ou que tiveram atrasos significativos para re-estadiamento e/ou realização da cirurgia. Todos foram estadiados através de toque retal, colonoscopia, TC de tórax e de abdome, e RM de pelve e igualmente re-estadiados 8 semanas após o término da neoadjuvância, operados e submetidos a excisão total do mesorreto. Os pacientes foram divididos em 2 grupos: A) menos de 12 LN, e B) 12 ou mais LN. Foram estudadas as possíveis variáveis relacionadas ao número de LN obtidos: sexo, idade, presença de LN acometidos, tamanho do tumor, localização da altura do tumor no reto, comprimento da peça, preservação esfincteriana, via de acesso, estadiamento inicial, grau de resposta tumoral e resposta patológica à quimiorrradioterapia neoadjuvante. Resultados: Noventa e cinco pacientes (60 masculinos) preencheram os critérios de inclusão e conseguiram ser tratados, re-estadiados e operados dentro das datas pré-estabelecidas. A média de LN ressecados foi 23,2 (3-67). Resposta patológica completa foi obtida em 18 pacientes (19%). Um mínimo de 12 LN foram obtidos em 81 pacientes (85%). Dentre os 14 doentes que obtiveram menos de 12 LN, 7 (50%) eram respostas patológicas completas. De todas as variáveis estudadas apenas resposta patológica completa na peça foi fator associado à não obtenção do número mínimo de 12 LN (p=0,002). Conclusões: Em pacientes submetidos à QRN e ETM, a resposta patológica completa foi o único fator associado a não obtenção de um mínimo de 12 de LN na peça / INTRODUCTION: According to the International Union against Cancer a minimum of 12 lymph nodes (LN) must be obtained from the surgical specimen for staging colorrectal cancer. However, recent studies reported that neoadjuvant chemoradiation may result in failure to obtain a minimum number of LN in 30-52 % of patients. OBJECTIVE: To identify factors associated with decreased number of LN resected in patients undergoing neoadjuvant therapy followed by total mesorectal excision (TEM). METHODS: From January/2012 to March/2013, 160 patients with rectal cancer underwent CRT (5 - FU and Gys 5040) followed by TEM and ligation of inferior mesenteric vessels in the roots. Patients with stage T3, T4 and/or N + within 10cm from anal verge were included. Patients with T2N0 located within 7cm from the anal verge were also included. Patients who were not able to complete the chemoradiation treatment or who presented significant delay on restaging and/or surgery were excluded from analyses. All patients were staged by digital rectal examination, colonoscopy, CT of the abdomen and chest, and MRI of the pelvis. Patients were re-staged 8 weeks after completion of neoadjuvant therapy, and submitted to total mesorectal excision right after that. Patients were stratified according to LN retrieval in two groups: A) less than 12 LN, B) 12 or more LN. Possible factors associated with the decreased number of LN were evaluated: gender, age, presence of metastatic LN, tumor size, tumor location, and length of the specimen, sphincter preservation, surgical access, initial staging, tumor regression grade and pathological response to chemoradiation. RESULTS: Ninety-five patients (60 male) met the inclusion criteria and were able to be treated, re-staged and operated within the pre-established intervals. The mean number of resected LN was 23.2 (3-67). Pathological complete response was achieved in 18 patients (19%). A minimum of 12 LN were obtained from 81 patients (85%). Half of the 14 patients with less than 12 LN presented pathologic complete response. Of all the variables studied only pathologic complete response was associated with less than 12 LN yield (p = 0.002). CONCLUSIONS: In patients submitted to chemoradiation followed by TME the complete pathological response was the only factor associated with failure to obtain a minimum of 12 LN in the specimen
224

Energy Optimization for Wireless Sensor Networks using Hierarchical Routing Techniques

Abidoye, Ademola Philip January 2015 (has links)
Philosophiae Doctor - PhD / Wireless sensor networks (WSNs) have become a popular research area that is widely gaining the attraction from both the research and the practitioner communities due to their wide area of applications. These applications include real-time sensing for audio delivery, imaging, video streaming, and remote monitoring with positive impact in many fields such as precision agriculture, ubiquitous healthcare, environment protection, smart cities and many other fields. While WSNs are aimed to constantly handle more intricate functions such as intelligent computation, automatic transmissions, and in-network processing, such capabilities are constrained by their limited processing capability and memory footprint as well as the need for the sensor batteries to be cautiously consumed in order to extend their lifetime. This thesis revisits the issue of the energy efficiency in sensor networks by proposing a novel clustering approach for routing the sensor readings in wireless sensor networks. The main contribution of this dissertation is to 1) propose corrective measures to the traditional energy model adopted in current sensor networks simulations that erroneously discount both the role played by each node, the sensor node capability and fabric and 2) apply these measures to a novel hierarchical routing architecture aiming at maximizing sensor networks lifetime. We propose three energy models for sensor network: a) a service-aware model that account for the specific role played by each node in a sensor network b) a sensor-aware model and c) load-balancing energy model that accounts for the sensor node fabric and its energy footprint. These three models are complemented by a load-balancing model structured to balance energy consumption on the network of cluster heads that forms the backbone for any cluster-based hierarchical sensor network. We present two novel approaches for clustering the nodes of a hierarchical sensor network: a) a distance-aware clustering where nodes are clustered based on their distance and the residual energy and b) a service-aware clustering where the nodes of a sensor network are clustered according to their service offered to the network and their residual energy. These approaches are implemented into a family of routing protocols referred to as EOCIT (Energy Optimization using Clustering Techniques) which combines sensor node energy location and service awareness to achieve good network performance. Finally, building upon the Ant Colony Optimization System (ACS), Multipath Routing protocol based on Ant Colony Optimization approach for Wireless Sensor Networks (MRACO) is proposed as a novel multipath routing protocol that finds energy efficient routing paths for sensor readings dissemination from the cluster heads to the sink/base station of a hierarchical sensor network. Our simulation results reveal the relative efficiency of the newly proposed approaches compared to selected related routing protocols in terms of sensor network lifetime maximization.
225

Model proudění chladicího média v synchronním stroji / Modeling of flow on synchronous generator

Chlup, Jaroslav January 2010 (has links)
This project deals with simulation´s possibilities of air flow in electric machines. A finite element method is the final element technique. Aim of this project is conversion universal formula for calculation friction dissipation factor. For its location is necessary to create 27 simulations according to the 2. plan order. Usage programme MATLAB for processing results obtain requisite algorithm for calculation friction dissipation factor.
226

Mechatronic Design and Verification of Autonomic Thermoelectric Energy Source for Aircraft Application / Mechatronic Design and Verification of Autonomic Thermoelectric Energy Source for Aircraft Application

Ančík, Zdeněk January 2016 (has links)
Předložená disertační práce řeší komplexní mechatronický návrh autonomního termoelektrického zdroje energie pro letecké aplikace. Na základě dostupných zdrojů a literatury práce popisuje současný stav problematiky. V práci jsou prezentovány simulační modely MEMS termoelektrických článků, které jsou ověřeny experimentálním testováním a hodnotami dostupnými od výrobce. Na základě metodiky model-besed design byly navrženy a vyrobeny tři demonstrátory. Jejich vlastnosti byly testovány v reálných podmínkách na letecké pohonné jednotce.
227

Novel zeotype frameworks with soft cyclodiphosphazane linkers and soft Cu₄X₄ clusters as nodes

Siddiqui, Mujahuddin M., Mobin, Shaikh M., Senkovska, Irena, Kaskel, Stefan, Balakrishna, Maravanji S. 26 November 2019 (has links)
Two novel cyclodiphosphazane cluster frameworks with Cu₄X₄ clusters as tetrahedral nodes and ferrocenyl cyclodiphosphazanes [Fe(η5-C5H₄)₂(PNtBu)₂] as ditopic linkers have been synthesized. These frameworks having sodalite topology display a unique integration of porosity and redox activity and offer new opportunities for the synthesis of zeotype frameworks with soft phosphorus-based ligands.
228

Degenerativní změny kloubních spojení u velkomoravské populace z lokality Mikulčice - Valy / Degenerative joint disease in Great Moravian population from the locality Mikulčice - Valy

Müllerová, Soňa January 2017 (has links)
This diploma thesis had two primary objectives. The first one was to examine if the incidence and development of primary degenerative joint disease (DJD) of the joints of the vertebral column and the limbs in an early medieval population from a cemetery by the sixth church in Mikulčice were affected mainly by the skeletal age of the deceased, or if other factor of physical loads was more significant. A set of 83 skeletal remains was evaluated primarily by Waldron's method (2009), but methods by Stloukal and Vyhnánek (1976); Buikstra and Ubelaker (1994); and Sager (1969) were also used. Schmorl nodes and eburnation were tracked too. Evaluated were vertebral joint (both intervertebral and apophyseal), jaw and limb joints. The results indicate that the incidence of degenerative joint disease in intervertebral joints, temporomandibular joint and appendicular joints is significantly affected by age, with the onset of degeneration being after the 40th year of skeletal age. No correlation of incidence of Schmorl nodes with age was present, and only a few cases of eburnace were noted. The relationship between the presence of DJD and the sex of the skeletons was not approved. I have compared these results with those from similar studies. I have deemed the primary evaluation by Waldron's method to be good...
229

Lokální steroidogeneze v periferních tkáních a její regulace / Local steroidogenesis in peripheral tissues and its regulation

Langová, Veronika January 2018 (has links)
The innate and adaptive immune processes are modulated by hormones including glucocorticoids and by microbiota. The exact mechanisms underlying the microbial and hormonal contributions to this control are not completely clear. Present study is therefore focused to crosstalk between microbiota and de novo biogenesis or local regeneration of glucocorticoids. In particular, the study analysed the effect of commensal microbiota on expression of genes encoding steroidogenic enzymes (Star, Cyp11a1, Hsd3b1, Cyp21a1, Cyp11b1) and regeneration of glucocorticoids (Hsd11b1) in adrenal glands, colon, spleen and mesenteric lymph nodes using conventional and germ-free mice. The expression of all 5 components of steroidogenesis was identified only in the adrenal gland and colon, whereas the lymphoid organs expressed predominantly Star, Cyp11a1 and Hsd3b1 indicating the ability to produce only progesterone but not corticosterone. Microbiota decreased the expression of Star in all studied tissues but the expression of other genes was insensitive to microbiota or did not respond homogenously depending on the tissue and gene. Hsd11b1 expression was upregulated by microbiota in the spleen but not in other tissues. Similarly, the in vitro treatment of immune cells isolated from mesenteric lymph nodes by microbial...
230

Impact of Metabolic Stress, Microbiome, and Lymph Node Colonization on <i>Salmonella</i> Shedding in Dairy Cattle

Munoz Vargas, Lohendy M. 11 August 2017 (has links)
No description available.

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