• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 35
  • 8
  • 5
  • 4
  • 3
  • 3
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 72
  • 10
  • 7
  • 6
  • 6
  • 6
  • 6
  • 6
  • 6
  • 5
  • 5
  • 5
  • 5
  • 5
  • 4
  • 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.
51

Characterisation of critical interactions between translation factors eIF2 and eIF2B

Murphy, Patrick January 2013 (has links)
Eukaryotic translation initiation is a complex and highly regulated process involving the ribosome, mRNA and proteins called eukaryotic initiation factors (eIFs). The overall aim of translation initiation is to position the ribosome at the initiation codon of the mRNA. eIF2, in its GTP-bound conformation, binds the initiator tRNA (Met-tRNAiMet) and delivers it to the 40S ribosomal subunit. When the anticodon of the tRNA is bound to the initiation codon, the GTP on eIF2 is hydrolysed to GDP. The guanine nucleotide exchange factor (GEF) eIF2B regenerates eIF2-GTP. eIF2 and eIF2B are multisubunit/multidomain protein complexes. Because information regarding the interface between each complex is limited, particularly the interface on the eIF2γ subunit, which binds the guanine-nucleotides and Met-tRNAiMet, interactions between the minimal GEF domain of eIF2Bε, εGEF, and eIF2 were mapped using mutagenesis and an in vitro cysteine cross-linking approach, with the cross-linker Mts-Atf-Biotin. Site-directed mutagenesis (SDM) was used to mutate five N-terminal and five C-terminal surface-exposed εGEF residues to cysteines. The mutant alleles were analysed in Saccharomyces cerevisiae and it was found that the gcd6-R574C allele was lethal and the gcd6-T572C was Gcd-. Further gcd6-R574 mutant alleles were also found to be lethal in yeast but expressed in vivo.εGEF-R574C has dramatically reduced GEF activity in vitro and binding assays showed that this mutant has significantly reduced affinity for eIF2. The εGEF-T572C and εGEF-S576C mutants also have severe and minor eIF2-binding defects respectively, while the C-terminal εGEF-Cys mutants have slightly reduced affinity for eIF2. The N-terminal εGEF-Cys mutants cross-link specifically to eIF2γ, while the C-terminal εGEF-Cys mutants interact predominantly with eIF2β. From the data obtained in this study, we propose a new model for eIF2B-mediated guanine-nucleotide exchange that reduces the importance of eIF2β and suggests εGEF resembles other GEFs in binding primarily to its G protein partner eIF2γ.
52

Tahové a únavové zkoušky tenkých vláken a fólií / Tensile and Fatigue Testing of Thin Fibres and Foils

Štěrbáček, Jaroslav January 2008 (has links)
A testing system MTS Tytron 250 with an original construction was bought at the Institute of Physics of Materials, AVCR v.v.i. The main aim of this diploma thesis was to obtain experiences with the controlling of the system and with its advantages and limitations. The tensile tests were performed on Al fibres with diameters of 125 micrometer, 180 micrometer a 500 micrometer, nylon fibres of 250 micrometer and 500 micrometer and tensile and cyclic tests on Al foil of 77 micrometer in thickness. It was found that the machine is suitable for testing of either subtle specimens with low loading forces or specimens with low stiffness as e.g. polymers or very long metallic or ceramic fibres. On the other side, the Tytrom system is not able to perform tests on specimens with a high stiffness and high loading forces. Material parameters were determined with a high reproducibility. Advantages and limitations of several types of subtle specimen's fixation into the grips were studied too.
53

Diverzita a abundance ptáků podél výškového gradientu Kamerunských hor / Diversity and abundances of birds along altitudinal gradients of Cameroon Mountains

Dubský, Marek January 2020 (has links)
The aim of this thesis is to describe the changes of bird species diversity along elevation gradient on six mounts in Cameroon and nearby Bioko island. The results of the analyses confirm most of the defined hypotheses, especially they show that species diversity declines with altitude and rises with area. Cluster analysis shows the similarity of individual mountains in particular altitude zones. Despite the original hypothesis, mount Cameroon is found to be most similar to mount Kupé, although high mountain assemblages of mount Cameroon and Bioko island are very alike as well. The absolutely highest diversity was detected on mount Cameroon and mount Kupé, but above 2100 m above sea level mounts Oku and Manenguba are the most diverse. The results of this thesis contribute to a clearer notion about factors influencing species diversity; however, more thorough data (particularly from mount Nlonako) and data extension for e.g. bird abundance would enrich the study and it would enable us to perform more detailed diversity analysis, especially an analysis of competition relationship among species. Key words Species diversity, Cameroon, bird assemblages, elevational gradient
54

Krystalochemie pyroxenů a amfibolů z Českého středohoří / Crystal chemistry of pyroxenes and amphiboles from the České středohoří

Kallistová, Anna January 2010 (has links)
Contents of major, minor and trace elements in clinopyroxenes and clinoamphiboles of basanites, volcanoclastics, essexites, sodalitic syenites, and monzodiorites of the České středohoří Mts. has been determined using an electrone microprobe and LA-ICP-MS techniques. Composition of clinopyroxenes corresponds to either diopside or augite and clinoamphiboles can be classified as kaersutite or pargasite. Some pyroxenes display pronounced sector zoning showing increased contents of Mg and Si in pyramidal sectors whereas prismatic sectors show Fe, Ti and Al enrichment. Chemical composition of both sectors corresponds to diopside. Growth zoning has been found in the samples from basanites and volcanoclastics. Grain cores display the chemistry of augite and towards the rim the chemical composition changes to diopside. Samples have also been analyzed by powder and single crystal X-ray diffraction techniques. Samples of pyroxenes appear to be either pure or they contain negligible admixtures of phlogopite. Samples of amphiboles are also either without any admixtures or they show contamination by low amounts of diopside or augite, or phlogopite may rarely be encountered. Mutual relationship between the size of the unit cell parameters b and and substitutions in M1,2,3 and A sites has been observed. Longer mean T-O...
55

Krystalochemie slíd z Českého středohoří / Crystal chemistry of micas from České středohoří

Goll, Jan January 2010 (has links)
Micas from České středohoří mts. have been studied by X-ray difractometry, ICP-MS and electron microprobe. The measurements of trace elements and REEs revealed very low tendency by normalization of chondrite reservoir and primitive mantle. The micas classifications were determined by Tischendorf (2007) and Rieder (1998) as Fe- or Fe-Ti phlogopites. The abundances of Ti are very high up to 0,46 (a.p.f.u.). X-ray powder diffraction revealed double layered polytype 2M1 with space group C/2c.
56

Krystalochemie slíd z Českého středohoří / Crystal chemistry of micas from České středohoří

Goll, Jan January 2011 (has links)
Six methods have been used to study micas from České středohoří mts.: X-ray difractometry (transmission and reflection), ICP MS, electron microprobe, Mössbauer spectroscopy and termogravimetry. The measurements of trace elements and REE's revealed very low tendency by normalization on chondrite reservoir and primitive mantle. Micas show high contents of TiO2 (9,47 wt.%) and BaO (up to 2,1 wt.%) in separated grains from rock. The micas classifications were determined by Tischendorf (2007) and Rieder (1998) as Fe-phlogopites. X-ray powder diffraction revealed cell dimensions and a common polytype 1M with space group C2/m. By Mössbauer spectroscopy have been studied the rates of Fe2+ /Fe3+ and they were 1,08 - 1,86 (except rock sample, which were 9:1). Termogravimetrical measurement until 1450řC revealed weight jump from 1120řC to 1270řC.
57

Morfologie fosilních tříděných strukturních půd Krkonoš / Structure of non-active sorted patterned ground in the Giant Mts.

Uxa, Tomáš January 2011 (has links)
Sorted patterned ground are a group of periglacial microforms which create more or less symmetrical forms due to frost action and especially repeated freeze-thaw cycles. The origin of sorted patterned ground in the Giant Mts. is presumed in late Pleistocene and they are suggested to be recently inactive (with the exception of sorted circles). Their occurrence is linked to the topmost localities with flat surfaces and intense wind action which causes low snow cover and allow deep soil freezing. The submitted diploma thesis deals with the influence of site characteristics (such as microclimatic extremity, terrain morphology and lithology) on morphology and sorting degree of sorted patterned ground. Field research was carried out along a transect tracing the microclimatic extremity gradient (represented by altitude and so-called relative snow height) in area of Mt. Luční hora in the eastern part of the Giant Mts. which in relatively homogeneous from the viewpoint of lithology and wind exposure. The transect was further extended across the Modré sedlo Saddle to the Mt. Studniční hora where there also occur various types of fossil sorted patterned ground or quasi- active sorted circles in the Modré sedlo Saddle, respectively. However, there is a variability of lithological as well as altitude...
58

Morfostrukturní analýza Hřibovské hornatiny / Morphostructural analysis of the Hřibovská hornatina

Stemberk, Jakub January 2011 (has links)
Morphostructural analysis of the Hřibovská hornatina Mts. This work deals with morphostructure analyses of the Hřibovská hornatina Mts., part of the Rychlebské hory Mts. Northeastern border of the studied area is created by the mountain front slope controlled by the Sudetic Marginal fault, which is one of the most conspicuous tectonic structures in central Europe. This is the main reason why works were focused on the analyses of stream network parameters and spatial distribution of those selected landforms which could potentially indicate recent tectonic activity in the studied area. As a result, supposed courses of faults marked in morphology were suggested. Fault activity assessment was considered on changes in erosion intensity indicated in longitudinal and crosswise profiles of stream valleys. Based on the values of Stream-Length index the areas with recent tectonic activity were delimited. The final output of this work is the morphostructure map of the Hřibovská hornatina Mts. and the adjacent area. Key words: Morphostructural analysis, active tectonics, Sudetic Marginal Fault, Hřibovská hornatina Mts.
59

Reducering av kapitalbindning hos producerande SME:s

Lindström, Marcus, Makushenko, Anton January 2022 (has links)
Introduktion: Små till medelstora företag (SME) innefattar 99.9% av alla aktiva verksamheter i Sverige. SME:s är företag som har begränsade ekonomiska resurser. Begränsade resurser kan leda till att verksamheter producerar produkter till lager i rädslan om att gå miste om leveranser, vilket skapar ett uppbundet kapital i färdigvarulagret. Syftet med studien är att undersöka om make to order (MTO) kan användas av SME:s för att reducera kapitalbindning i färdigvarulagret och undersöka vilka utmaningar det finns med att implementera MTO.  FF1: Hur kan MTO användas som ett verktyg för att reducera kapitalbindningen hos SME:s? FF2: Vilka utmaningar finns det med att implementera MTO för SME:s?  Metod: En fallstudie har genomförts hos ett producerande mikroföretag. Data har samlats in genom observationer, intervjuer och dokument. För grund till den teoretiska referensramen har en litteraturstudie genomförts. Litteraturstudien samlade in data genom vetenskapliga artiklar och böcker som har använts för att analyser den insamlade empirin från fallstudien.   Resultat: Studiens resultat har kommit fram till att MTO kan användas som ett verktyg hos SME:s som har en hög kapitalbindning och inte kan utesluta ett färdigvarulager. För att reducera kapitalbindningen kan därmed en hybrid mellan MTO och MTS (make to stock) användas. Studien har ytterligare kommit fram till att det finns tre huvud utmaningar med att implementera MTO. De tre utmaningarna är ställtider, oförutsägbara händelser och förändringar.
60

Druhová diverzita ptáků podél výškového gradientu Kamerunských hor / Diversity of bird species along elevational gradient on Cameroon mountains

Dubský, Marek January 2021 (has links)
The aim of this thesis is to describe the changes of bird species diversity along elevation gradient on six mounts in Cameroon and nearby Bioko island. The results of the analyses confirm most of the defined hypotheses, especially they show that species diversity declines with altitude and rises with area. The absolutely highest diversity was detected on mount Kupé and mount Cameroon, but above 2100 m above sea level mounts Oku and Manenguba are the most diverse. Other analysis showed that the biggest changes in beta diversity of bird assemblages along altitudinal gradients are on the lowest elevational belts which are on the edges of a degraded habitats and continuous undisturbed forests. Other important changes in bird assemblages happen around altitude 1200 m, where the assemblages of lowland rainforest change to assemblages of mountain forest. Analyses of affinity of bird species to forest habitat showed that the most affined assemblages to the forest are those found on mounts Kupé and Rata. On the other hand bird assemblages on mounts Manenguba and Oku are the one of least affined to the forest biotope. Analysis of habitat generalism and specialism did not show the expected outcome and for clearer results the design of analysis needs to be improved. The results of this thesis contribute to a...

Page generated in 0.0248 seconds