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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

Ação dos hormônios Stanniocalcina-1 e Stanniocalcina-2 sobre o metabolismo de aminoácidos em ratos / Actions of the hormones Stanniocalcin-1 and Stanniocalcin-2 on the amino acid metabolism in rats

Rossetti, Camila Lüdke January 2013 (has links)
As Stanniocalcinas (STC1 e STC2) são hormônios glicoproteicos originalmente encontrados em peixes teleósteos. Em mamíferos, esses hormônios são expressos em uma variedade de tecidos e estão envolvidos em processos como o transporte de cálcio e fosfato pelos rins e intestino, a carcinogênese, a reprodução e o crescimento. Recentemente, foram encontrados efeitos da STC1 e da STC2 no metabolismo intermediário. Sítios de ligação para a STC1 já foram identificados na membrana mitocondrial e resultados preliminares do nosso laboratório demonstraram que a STC1 possui um efeito inibitório sobre a gliconeogênese renal e tanto a STC1 quanto a STC2 diminuem a incorporação de 14C-glicose em 14CO2 no fígado e no músculo gastrocnêmio, respectivamente, de ratos. No entanto, o papel desses hormônios no metabolismo de aminoácidos permanece desconhecido. No presente trabalho, as ações da STC1 e da STC2 foram avaliadas no fígado e no músculo gastrocnêmio excisados de ratos machos (Rattus norvegicus, n=48 animais) de 300±50g, alimentados ad libitum. Os resultados obtidos mostram que a STC1, no fígado, diminuiu a captação do ácido 2-(metilamino)isobutírico, aumentou a atividade da bomba Na+/K+-ATPase, diminuiu a atividade da enzima malato desidrogenase mitocondrial e estimulou a síntese de glicogênio a partir da alanina. A STC2, no fígado, diminuiu a atividade da enzima malato desidrogenase mitocondrial, estimulou a síntese de proteínas a partir de leucina, e estimulou a síntese de glicogênio a partir de alanina. Já, no músculo, a STC2 estimulou a oxidação de leucina e a incorporação desse aminoácido em proteínas. Esses resultados confirmam a existência de ações das STC1 e STC2 no metabolismo de aminoácidos e sugerem, com exceção da ação da STC2 sobre a enzima malato desidrogenase, um papel anabólico para a STC2 em ambos os tecidos. A mesma afirmação não pode ser feita para a STC1, que apresentou efeitos antagônicos no tecido hepático. Por fim, o trabalho mostrou que as ações da STC1 e da STC2 sobre as vias metabólicas dos aminoácidos ocorrem com a utilização de doses muito baixas desses hormônios. / Stanniocalcins (STC) are glycoprotein hormones that were first discovered in teleostean fishes. In mammals, these hormones are expressed in a variety of tissues. Besides its role on the calcium and phosphate transport by the kidneys and intestine, they are involved in processes such as carcinogenesis, reproduction and growth. Recently it has been shown that STC1 and STC2 affect the control of intermediary metabolism. Binding sites for STC1 have been already identified in the mitochondrial membrane. Preliminary results of our laboratory showed that STC1 has an inhibitory effect on renal gluconeogenesis in rats and both STC1 and STC2 decrease the 14C-glicose incorporation into 14CO2 in the liver and the gastrocnemius muscle, respectively. Despite these evidences that STC1 and STC2 have a role in the control of glucose and lipids metabolism, the function of these hormones in amino acids metabolism remains unknown. In the present study, the STC1 and STC2 actions were evaluated in livers and gastrocnemius muscles excised from male rats (Rattus norvegicus, n=48 animals). The rats weighted 300±50g and were fed ad libitum. The results show that STC1 decreased 2-(metilamine)isobutyric acid uptake, increased Na+/K+-ATPase activity, decreased mitochondrial malate dehydrogenase activity and stimulated glycogen synthesis from alanine. All actions of STC1 were shown in the hepatic tissue and this hormone did not affect any parameter in muscular tissue. In the liver, STC2, decreased the mitochondrial malate dehydrogenase activity, stimulated protein synthesis from leucine and stimulated glycogen synthesis from alanine. In muscle, STC2 stimulated leucine incorporation into CO2 and proteins. These results confirm the regulatory role of STC1 and STC2 on amino acid metabolism in muscle and liver of rats. They suggest, with exception to the STC2 action into the hepatic malate dehydrogenase, an anabolic role for STC2 in both tissues. However this cannot be stated for STC1, which show antagonistic effects in the hepatic tissue. Lastly, another important finding of this study is that STC1 and STC2 actions on amino acid metabolism occur with low hormone concentrations.
22

Analysis of Spleen-Induced Fimbria Production in Recombinant Attenuated Salmonella enterica Serovar Typhimurium Vaccine Strains

Łaniewski, Paweł, Baek, Chang-Ho, Roland, Kenneth L., Curtiss, Roy 22 August 2017 (has links)
Salmonella enterica serovar Typhimurium genome encodes 13 fimbrial operons. Most of the fimbriae encoded by these operons are not produced under laboratory conditions but are likely to be synthesized in vivo. We used an in vivo expression technology (IVET) strategy to identify four fimbrial operons, agf, saf, sti, and stc that are expressed in the spleen. When any three of these operons were deleted, the strain retained wild-type virulence. However, when all four operons were deleted, the resulting strain was completely attenuated, indicating that these four fimbriae play functionally redundant roles critical for virulence. In mice, oral doses of as low as 1 x 10(5) CFU of the strain with four fimbrial operons deleted provided 100% protection against challenge with 1 x 10(9) CFU of wild-type S. Typhimurium. We also examined the possible effect of these fimbriae on the ability of a Salmonella vaccine strain to deliver a guest antigen. We modified one of our established attenuated vaccine strains, chi 9088, to delete three fimbrial operons while the fourth operon was constitutively expressed. Each derivative was modified to express the Streptococcus pneumoniae antigen PspA. Strains that constitutively expressed saf or stc elicited a strong Th1 response with significantly greater levels of anti-PspA serum IgG and greater protective efficacy than strains carrying saf or stc deletions. The isogenic strain in which all four operons were deleted generated the lowest anti-PspA levels and did not protect against challenge with virulent S. pneumoniae. Our results indicate that these fimbriae play important roles, as yet not understood, in Salmonella virulence and immunogenicity. IMPORTANCE Salmonella enterica is the leading cause of bacterial food-borne infection in the United States. S. Typhimurium is capable of producing up to 13 distinct surface structures called fimbriae that presumably mediate its adherence to surfaces. The roles of most of these fimbriae in disease are unknown. Identifying fimbriae produced during infection will provide important insights into how these bacterial structures contribute to disease and potentially induce protective immunity to Salmonella infection. We identified four fimbriae that are produced during infection. Deletion of all four of these fimbriae results in a significant reduction in virulence. We explored ways in which the expression of these fimbriae may be exploited for use in recombinant Salmonella vaccine strains and found that production of Saf and Stc fimbriae are important for generating a strong immune response against a vectored antigen. This work provides new insight into the role of fimbriae in disease and their potential for improving the efficacy of Salmonella-based vaccines.
23

NTA-materialet som stöd för systematiska undersökningar i NO-undervisningen : En studie om elevernas möjligheter att utveckla förmågan att genomföra systematiska undersökningar med NTA-materialet i årskurs F-3 / STC in support of scientific inquiry in science teaching

Tunström, Isabelle January 2021 (has links)
Syftet med denna studie har varit att undersöka på vilka sätt läromaterialet NTA gerförutsättningar för elever i årskurs F-3 att utveckla förmågan att genomföra systematiskaundersökningar samt hur lärare använder materialet. Studien har grundats på tresemistrukturerade intervjuer av lärare samt en innehållsanalys av textmaterial tillhörande treolika NTA-teman. De intervjuer som genomfördes är även de analyserade med hjälp av eninnehållsanalys. Resultatet för intervjuerna visade på att lärarna använder sig av NTAmaterialetför att utveckla elevernas förmåga till att genomföra systematiska undersökningargenom att dels utföra uppdragen i ett tema enligt beskrivningarna dels genom att utförauppdragen med anpassningar till den aktuella gruppen. Intervjuerna visade även på hur lärarnakunde se tydliga kopplingar till läroplanen och de kunskapskrav som eleverna ska uppnå.Dessutom ansåg de att NTA-materialet ger förutsättningar för att blanda det teoretiska arbetetmed praktiskt arbete där lärarna även ansåg att materialet är genomtänkt. NTA-materialet ansesdärmed vara en hjälp för lärarna att få ihop en bra undervisning kopplat till läroplanen. Dockframkom det att materialet kan vara tidskrävande i förberedelserna och att uppdragen iblandliknar varandra för mycket och vissa delar hoppas över för att spara tid. Avslutningsvisframkom det av intervjuerna att NTA-materialet är ett bra redskap för att utveckla elevernasförmåga att genomföra systematiska undersökningar men att det ibland kan bli begränsande förelever som har svårt att tänka utanför boxen eller om uppdragen är för svåra för eleverna för attkomma till steget att genomföra egna undersökningar. Vid analysen av textmaterialet för de treNTA-temana framkom det att materialet hjälper eleverna till en utveckling av förmågan attgenomföra systematiska undersökningar men att det till större del i uppdragen endast är en litendel av en förmågemålet som eleverna får öva på. Det framkom inte från något uppdrag atteleverna fullständigt fick pröva på att genomföra en systematisk undersökning även om detfanns enstaka uppdrag som var i närheten av fullständiga. Av de olika delarna en systematiskundersökning består av var möjligheten att ställa egna frågor samt deltagande i planeringenbegränsad för eleverna. Lite mer vanligt förekommande var möjligheten till att utvärderaarbetet. Möjligheterna till att ställa egna hypoteser samt dokumentation var det som förekom mest. / <p>NO</p>
24

Recherche de sécrétagogues naturels du GLP-1 : exploration du potentiel antidiabétique d'espèces du genre Cynanchum (Apocynaceae) / Research for natural GLP-1 secretagogues : exploration of the antidiabetic potential of Cynanchum species (Apocyanceae)

Tsoukalas, Michail 14 September 2015 (has links)
Dans le cadre de la recherche de composés pouvant stimuler la sécrétion de l’hormone hypoglycémiante GLP-1 (glucagon-like-peptide 1) et sur des critères ethno-pharmacologiques et taxonomiques, différentes Asclepiadoidées ont été criblées sur un modèle cellulaire (lignée STC-1). Cette approche nous a permis de sélectionner deux espèces de Cynanchum malgaches. L’isolement bio-guidé de C. marnierianum a conduit à la purification de 2 nouveaux glycosides prégnaniques, les marnieranosides. L’exploration phytochimique de C. menarandrense a permis l’identification de 5 nouvelles structures prégnaniques et de 2 prégnanes déjà signalés dans un genre taxonomiquement proche et hypoglycémiant : Caralluma. Les prégnanes purifiés ont aussi été évalués pour leur effet sécrétagogue GLP-1 et cytotoxique mais seuls les marnieranosides se sont avérés bioactifs. Des analogies structurales entre les molécules identifiées dans le genre Cynanchum et des molécules bioactives isolées au préalable d’espèces antidiabétiques (genres Hoodia et Caralluma) valident notre stratégie pour la découverte des métabolites secondaires avec un potentiel antidiabétique. / In the framework of our search for antidiabetic compounds capable of stimulating the secretion of the hypoglycemic hormone GLP-1 (glucagon-like-peptide 1), based on ethnopharmacological and taxomic criteria, several Asclepiadoidae plants were screened with an in vitro model (STC-1 cell line). This approach led to the selection of two Malagasy Cynanchum species.Bio-guided fractionation of C. marnierianum led to the purification of two new pregnane glycosides named marnieranosides. The phytochemical study of C. menarandrense led to the identification of 5 new pregnane structures along with 2 pregnanes previously reported in the closely related and hypoglycemic Caralluma genus. The isolated pregnanes were evaluated for their GLP-1 secretagogue and cytotoxic activity but only the marnieranosides were proven bioactive. Structural similarities of the Cynanchum pregnanes with the ones previously isolated from antidiabetic plants (Hoodia and Caralluma), validated our approach for the discovery of secondary metabolites with antidiabetic potential.
25

Kollegialt lärande : En studie av lärare som arbetar utifrån en modell för att utveckla sin undervisning

Johansson, Ulrika January 2015 (has links)
Syftet med studien är att undersöka vad lärare samtalar om när de deltar i kollegiala träffar enligt NTA Skolutvecklings modell för att förbättra sin undervisning främst inom de naturvetenskapliga ämnena biologi, fysik och kemi. Syftet är också att undersöka handledarens roll vid träffarna, vad som händer i klassrummet mellan träffarna, identifiera möjligheter och hinder för kollegialt lärande samt få ökad förståelse för lärares forskningsanvändning. Studien utgår från kvalitativa forskningsmetoder och material till studien har samlats in genom deltagande observation, transkribering av filmning, samtal, insamling av data och enkät mm. Jag har noggrant och systematiskt bearbetat insamlat material och fördjupat mig i forskning om ämnet. Min undersökning visar att lärare som deltog på dessa träffar var fokuserade på träffens tema. Fokus i samtalen ligger på lärarens egen undervisning och de egna elevernas möjligheter till lärande. Lärarna diskuterade dilemman i klassrummet och reflekterade över händelser i klassrummet. De diskuterade tekniker att använda i klassrummet t ex för att aktivera alla elever, att hjälpa elever att fokusera på rätt saker, tydlighet, feedback (formativa strategier). De diskuterade även begrepp inom NO, språkets betydelse, vikten av att variera undervisningen beroende på kontext samt läraruppdragets komplexitet. Handledaren hade en viktig roll att leda de ämnesdidaktiska diskussionerna och modellen bidrog till att aktiviteter genomfördes i klassrummet mellan träffarna. Kontinuerlig kompetensutveckling kan bedrivas på många sätt varav kollegialt lärande är ett sätt. Engagemang och variation är viktiga komponenter i all kompetensutveckling. Jag har identifierat olika hinder för kollegialt lärande bl a brist på tid och bristande kontinuitet. Lärarna i studien önskar fler möjligheter till diskussion och reflektion kring sin praktik och aktuell forskning. Min undersökning visar även att skolan är komplex och att fältet mellan forskning och beprövad erfarenhet också är komplext.
26

Analysis of Communication Architecture of GCDC 2011 / Analysis of Communication Architecture of GCDC 2011

Khaksari, Mohammadreza January 2011 (has links)
This thesis report presents a method to analyze the communication architecture for the Intelligent Transportation Systems (ITS). The report also includes a case study on ASN.1 notation and analysis of its encoding rules. Included in the report is also: (i) accompanying instruction on how to use ASN.1 compilers to produce the C/C++ message encoder/decoder, and (ii) analysis of Non-IP communications of Communication Access for Land Mobiles (CALM-FAST) protocol stack in ITS. The thesis is a part of the research project entitled “SCOOP”, a joint project between SCANIA CV AB and KTH. The purpose of this thesis is to contribute to the ultimate goal, which is to equip a vehicle with necessary hardware and software technology to provide a platooning behavior in the GCDC 2011 competition. This goal is achieved by the means of wireless communication system for both vehicle to vehicle and vehicle to road side units communications in the platoon. Overall, this thesis introduces the important usage of ASN.1 in implementation of cut-edge telecommunication systems especially in V2V and V2I communication; and clarifies the CALM-FAST protocol stack in mobile nodes. / Kartlägga CALM-FAST protokollet och hur det användes tillsammans med den i tävlingen GCDC 2011 fastslanga kommunikationsprotokollet. GCDC var ett tävling i kooperativ körning arrangerad och initierad av Hollänska TNO och gick ut på att få fordon att agera tillsammans beserat på information sänt via WLAN 802.11p. ASN.1 användes och ingick i analysen.
27

Space-Time Coding with Offset Modulations

Nelson, N. Thomas 26 November 2007 (has links) (PDF)
In this dissertation it is shown that the telemetry versions of Feher-patented QPSK (FQPSK-JR) and shaped offset QPSK (SOQPSK-TG) can be interpreted as both cross-correlated, trellis-coded quadrature modulation (XTCQM) and continuous phase modulation (CPM). Based on these representations, both modulations can be detected with near optimal bit error rate performance using a common detector that is formulated as either an XTCQM detector, a traditional CPM detector, or a pulse amplitude modulation (PAM) detector (due to the PAM decomposition of the CPM representations of these modulations). In addition it is shown that the complexity of the XTCQM detector for SOQPSK-TG can be reduced by a factor of 128 with only a 0.2 dB loss in detection efficiency relative to the optimum detector. Three decoders for STC encoded OQPSK are presented. One decoder has a bit error rate performance that matches the SISO case but with much higher complexity than that of the QPSK decoder. A second decoder matches the simplicity of the decoder for STC encoded non-offset QPSK but with a loss of 3 dB relative to the single-input, single-output (SISO) case. A third decoder matches SISO performance with lower complexity than the first one. These results for STC encoded OQPSK are extended to STC SOQPSK. It is shown that the maximum likelihood decoder is not computationally feasible. Two suboptimal decoders based on the STC OQPSK decoders are presented. These decoders have much higher complexity than their OQPSK counterparts, and they provide inferior bit error rate performance. In addition, a least squares decoder for STC encoded SOQPSK is presented which is less complex and has better performance (within 1 dB of the SISO bound) than the previous two decoders. This decoder also handles the differential delays that can occur on aeronautical telemetry channels.
28

A Sociotechnical Systems Analysis of Building Information Modelling (STSaBIM) Implementation in Construction Organisations

Sackey, Enoch January 2014 (has links)
The concept of BIM is nascent but evolving rapidly, thus, its deployment has become the latest shibboleth amongst both academics and practitioners in the construction sector in the recent couple of years. Due to construction clients buy-in of the BIM concept, the entire industry is encouraged to pursue a vision of changing work practices in line with the BIM ideas. Also, existing research recognises that the implementation of BIM affects all areas of the construction process from design of the building, through the organisation of projects, to the way in which the construction process is executed and how the finished product is maintained. The problem however is that, existing research in technology utilisation in general, and BIM literature in particular, has offered limited help to practitioners trying to implement BIM, for focusing predominantly, on technology-centric views. Not surprisingly therefore, the current BIM literature emphasises on topics such as capability maturity models and anticipated outcomes of BIM rollouts. Rarely does the extant literature offer practitioners a cohesive approach to BIM implementation. Such technology-centric views inevitably represent a serious barrier to utilising the inscribed capabilities of BIM. This research therefore is predicated on the need to strengthen BIM implementation theory through monitoring and analysing its implementation in practice. Thus, the focus of this thesis is to carry out a sociotechnical systems (STS) analysis of BIM implementation in construction organisations. The concept of STS accommodates the dualism of the inscribed functions of BIM technologies and the contextual issues in the organisations and allows for the analysis of their interactive combination in producing the anticipated effect from BIM appropriation. An interpretive research methodology is adopted to study practitioners through a change process, involving the implementation of BIM in their work contexts. The study is based on constructivist ontological interpretations of participants. The study adopts an abductive research approach which ensures a back-and-forth movement between research sites and the theoretical phenomenon, effectively comparing the empirical findings with the existing theories and to eventually generate a new theoretical understanding and knowledge regarding the phenomenon under investigation. A two-stage process is also formulated for the empirical data collection - comprising: 1) initial exploratory study to help establish the framework for analysing BIM implementation in the construction context; and 2) case studies approach to provide a context for formulating novel understanding and validation of theory regarding BIM implementation in construction organisations. The analysis and interpretation of the empirical work follows the qualitative content analysis technique to observe and reflect on the results. The findings have shown that BIM implementation demands a complete breakaway from the status quo. Contrary to the prevailing understanding of a top-down approach to BIM utilisation, the study revealed that different organisations with plethora of visions, expectations and skills combine with artefacts to form or transform BIM practices. The rollout and appropriation of BIM occurs when organisations shape sociotechnical systems of institutions, processes and technologies to support certain practices over others. The study also showed that BIM implementation endures in a causal chain of influences as different project organisations with their localised BIM ambitions and expectations combine to develop holistic BIM-enabled project visions. Thus, distributed responsibilities on holistic BIM protocols among the different levels of influences are instituted and enforced under binding contractual obligations. The study has illuminated the centrality of both the technical challenges and sociological factors in shaping BIM deployment in construction. It is also one of the few studies that have produced accounts of BIM deployment that is strongly mediated by the institutional contexts of construction organisations. However, it is acknowledged that the focus of the research on qualitative interpretive enquiry does not have the hard and fast view of generalising from specific cases to broader population/contexts. Thus, it is suggested that further quantitative studies, using much larger data sample of BIM-enabled construction organisations could provide an interesting point of comparison to the conclusions derived from the research findings.
29

Diabetes-Induced Expression and Regulation of GLP-1 levels by Bile Acid Receptors (TGR5 & FXR)

Spengler, Joseph R 01 January 2017 (has links)
Diabetes Mellitus has continued to drastically affect the health of the world and many complications can prove fatal. As long as this metabolic disease persist, research discoveries will need to continue to be made so that patient outcomes and healthcare are dramatically enhanced. In recent years, GLP-1 has been the topic of conversation for diabetes research, due to its promising effects in promoting insulin sensitivity. Furthermore, bile acids and their receptors (TGR5 & FXR) have shown promise in their actions in the regulation of GLP-1, and thus glucose homeostasis. Here we have shown the detection and increased expression of TGR5 and GLP-1, and decreased expression of FXR in diabetic mouse intestinal mucosa tissues. We have also shown the detection and increased expression of these receptors in STC-1 cells. More importantly we have linked the connection of increased glucose concentration (hyperglycemia) to increased TGR5 activation to increased GLP-1 release, thus leading to increased insulin sensitivity and altered diabetic outcomes.
30

Space Time Coding For Wireless Communication

Acharya, Om Nath, Upadhyaya, Sabin January 2012 (has links)
As the demand of high data rate is increasing, a lot of research is being conducted in the field of wireless communication. A well-known channel coding technique called Space-Time Coding has been implemented in the wireless Communication systems using multiple antennas to ensure the high speed communication as well as reliability by exploiting limited spectrum and maintaining the power. In this thesis, Space-Time Coding is discussed along with other related topics with special focus on Alamouti Space-Time Block Code. The Alamouti Codes show good performance in terms of bit error rate over Rayleigh fading channel. The performance of Altamonte’s code and MIMO capacity is evaluated by using MATLAB simulation.

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