RNA recognition motifs (RRMs) are a ubiquitous class of proteins which bind RNA in a sequence-specific fashion, often with high affinity. The mechanisms through which this single protein domain recognizes diverse RNA sequences is not fully understood. High-resolution three-dimensional structures are particularly important in understanding the structural features required for RNA recognition and binding. This work presents the structure of an expanded RRM domain from the Drosophila melanogaster Bruno protein. The Bruno protein is involved in establishing proper body patterning during development. This is accomplished through the translational repression of several mRNAs, in particular, the oskar mRNA. Previous work has identified an expanded RRM domain within the Bruno protein. This RRM requires an additional forty amino acids prior to the start of the canonical RRM domain for high affinity RNA binding. The protein was found to contain a canonical RRM domain comprised of four anti-parallel [beta] strands and two [alpha] helices. The RRM is preceded by a ten amino acid loop that interacts with [alpha]₁ and [beta]₂, while the remaining amino acids are flexible in solution. Interestingly, the deletion of these residues does not alter the fold or stability of the RRM domain. Thus, these additional residues must be involved in RNA binding, as they are not required for structure. From these studies, the Bruno RRM represents a new example of protein features required for recognition and high affinity binding of RNA. / text

In this thesis, we investigate several radio resourcemanagement (RRM) techniques and concepts in an indoorenvironment with a dense infrastructure. Future wireless indoorcommunication networks will very likely be implemented atplaces where the user concentration is very high. At these hotspots, the radio resources must be used efficiently. The goalis to identify efficient RRM techniques and concepts that aresuitable for implementation in an indoor environment. Handling the high level of co-channel interference is shownto be of paramount importance. Several investigations in thethesis point this out to be the key problem in an indoorenvironment with a dense infrastructure. We show that a locallycentralized radio resource management concept, the bunchconcept, can give a very high performance compared to othercommonly used RRM concepts. Comparisons are made withdistributed systems and systems using channel selection schemeslike CSMA/CA. The comparisons are primarily made by capacityand throughput analysis which are made by system levelsimulations. Results show that the centralized concept can give85 percent higher capacity and 70 percent higher throughputthan any of the compared systems. We investigate several RRM techniques to deal with thechannel interference problem and show that beamforming cangreatly reduce the interference and improve the systemperformance. Beamforming, especially sector antennas, alsoreduce the transmitter powers and the necessary dynamic range.A comparison is made between the use of TD/CDMA and pure TDMAwhich clearly shows the performance benefits of usingorthogonal channels that separates the users and reduces theco-channel interference. Different channel selection strategiesare studied and evaluated along with various methods to improvethe capability of system co-existence. We also investigate several practical measures to facilitatesystem implementation. Centralized RRM is suitable forguaranteeing QoS but is often considered too complex. With thestudied centralized concept the computational complexity can bereduced by splitting the coverage area into smaller pieces andcover them with one centralized system each. This reduces thecomplexity at the prize of lost capacity due to theuncontrolled interference that the different systems produce.Our investigations show that sector antennas can be used toregain this capacity loss while maintaining high reduction incomplexity. Without capacity loss, the computational complexitycan be reduced by a factor of 40 with sectoring. Theimplementation aspects also include installation sensitivity ofthe indoor architecture and the effect of measurement errors inthe link gains. The robustness against installation errors ishigh but the bunch concept is quite sensitive to largemeasurement errors in the studied indoor environment. Thiseffect can be reduced by additional SIR-margins of the radiolinks. The studied bunch concept is shown to be promising for usein future wireless indoor communication systems. It provideshigh performance and is feasible to implement. Keywords:Radio resource management, indoorcommunication, the bunch concept, centralized RRM, dynamicchannel allocation, channel selection, co-channel interference,power control, feasibility check, capacity, throughput, qualityof service, beamforming, downtilting, sector antennas,co-existence, computational complexity, sensitivity analysis,measurement errors, infrastructure, system implementation,WLAN, HiperLAN/2, IEEE 802.11.

<p>The new mobile standard Long Term Evolution delivers high data rates, small delay and a more efficiently utilized RF spectrum. A solution to maintain this performance in user dense areas or areas with bad reception is the deployment of so-called femtocells. Femtocells are small base stations that are deployed indoors and share the RF spectrum with the whole mobile network. The idea is that femtocells will increase mobile operators network coverage and capacity while it at the same time increase users data throughput. There are several challenges with femtocells, both technical and economical ones. The most debated issues is how femtocells should schedule users while operating in an environment where other femtocells and base stations are interfering. In this work we developed a simulation tool to simulate the scheduling interaction between femtocells and base stationsin order to show the performance of radio resource schedulers. This rapport also aims to evaluate an approach to a femtocell scheduler to solve this issue in a satisfying way. The report gives a description of the structure of the implemented simulation tool together with some reflections on how future designs of similar or more complex simulation environments could be done.</p>

The new mobile standard Long Term Evolution delivers high data rates, small delay and a more efficiently utilized RF spectrum. A solution to maintain this performance in user dense areas or areas with bad reception is the deployment of so-called femtocells. Femtocells are small base stations that are deployed indoors and share the RF spectrum with the whole mobile network. The idea is that femtocells will increase mobile operators network coverage and capacity while it at the same time increase users data throughput. There are several challenges with femtocells, both technical and economical ones. The most debated issues is how femtocells should schedule users while operating in an environment where other femtocells and base stations are interfering. In this work we developed a simulation tool to simulate the scheduling interaction between femtocells and base stationsin order to show the performance of radio resource schedulers. This rapport also aims to evaluate an approach to a femtocell scheduler to solve this issue in a satisfying way. The report gives a description of the structure of the implemented simulation tool together with some reflections on how future designs of similar or more complex simulation environments could be done.

<p>In this thesis, we investigate several radio resourcemanagement (RRM) techniques and concepts in an indoorenvironment with a dense infrastructure. Future wireless indoorcommunication networks will very likely be implemented atplaces where the user concentration is very high. At these hotspots, the radio resources must be used efficiently. The goalis to identify efficient RRM techniques and concepts that aresuitable for implementation in an indoor environment.</p><p>Handling the high level of co-channel interference is shownto be of paramount importance. Several investigations in thethesis point this out to be the key problem in an indoorenvironment with a dense infrastructure. We show that a locallycentralized radio resource management concept, the bunchconcept, can give a very high performance compared to othercommonly used RRM concepts. Comparisons are made withdistributed systems and systems using channel selection schemeslike CSMA/CA. The comparisons are primarily made by capacityand throughput analysis which are made by system levelsimulations. Results show that the centralized concept can give85 percent higher capacity and 70 percent higher throughputthan any of the compared systems.</p><p>We investigate several RRM techniques to deal with thechannel interference problem and show that beamforming cangreatly reduce the interference and improve the systemperformance. Beamforming, especially sector antennas, alsoreduce the transmitter powers and the necessary dynamic range.A comparison is made between the use of TD/CDMA and pure TDMAwhich clearly shows the performance benefits of usingorthogonal channels that separates the users and reduces theco-channel interference. Different channel selection strategiesare studied and evaluated along with various methods to improvethe capability of system co-existence.</p><p>We also investigate several practical measures to facilitatesystem implementation. Centralized RRM is suitable forguaranteeing QoS but is often considered too complex. With thestudied centralized concept the computational complexity can bereduced by splitting the coverage area into smaller pieces andcover them with one centralized system each. This reduces thecomplexity at the prize of lost capacity due to theuncontrolled interference that the different systems produce.Our investigations show that sector antennas can be used toregain this capacity loss while maintaining high reduction incomplexity. Without capacity loss, the computational complexitycan be reduced by a factor of 40 with sectoring. Theimplementation aspects also include installation sensitivity ofthe indoor architecture and the effect of measurement errors inthe link gains. The robustness against installation errors ishigh but the bunch concept is quite sensitive to largemeasurement errors in the studied indoor environment. Thiseffect can be reduced by additional SIR-margins of the radiolinks.</p><p>The studied bunch concept is shown to be promising for usein future wireless indoor communication systems. It provideshigh performance and is feasible to implement.</p><p><b>Keywords:</b>Radio resource management, indoorcommunication, the bunch concept, centralized RRM, dynamicchannel allocation, channel selection, co-channel interference,power control, feasibility check, capacity, throughput, qualityof service, beamforming, downtilting, sector antennas,co-existence, computational complexity, sensitivity analysis,measurement errors, infrastructure, system implementation,WLAN, HiperLAN/2, IEEE 802.11.</p>

In the 3GPP LTE, different radio resource management (RRM) techniques have been proposed in order to improve the uplink performance. Frequency hopping is one of the techniques that can be used to improve the uplink performance by providing frequency diversity and interference averaging. The hopping can be between subframes (inter-subframe) or within a subframe (intra-subframe). 3GPP specifies two types of frequency hopping for the LTE uplink, hopping based on explicit hopping information in the scheduling grant and sub-band based hopping according to cell-specific hopping and mirroring patterns. In this master’s thesis, theoretical discussion on the frequency hopping schemes is carried out followed by dynamic simulations in order to evaluate the performance gain of frequency hopping. Based on the theoretical analysis, the second type of hopping is selected for detailed study. As a baseline for comparison, dynamic frequency domain scheduling with random frequency resource allocation has been used. Single cell and multi-cell scenarios have been simulated with VoIP traffic model using user satisfaction as a performance metric. The simulation results show that frequency hopping improves the uplink performance by providing frequency diversity in the single cell scenario and both frequency diversity and interference averaging in the multi-cell scenario. The gains in using the hopping schemes were reflected as VoIP capacity (the number of satisfied users) improvement. In this study, the performance of the selected hopping schemes under different hopping parameters is also evaluated. / ttma07@student.bth.se tariku.temesgen.mehari@ericsson.com

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L'expression génique est régulée à de nombreuses étapes de la vie cellulaire. La synthèse des protéines ou traduction, étape ultime de cette expression, est finement régulée. Elle comporte trois phases: l'initiation, l'élongation et la terminaison. L'initiation commence par l'établissement de la sous-unité ribosomique 40S sur cet ARNm qu'elle balaye ensuite jusqu'au codon initiation. Pour cela, des facteurs canoniques sont impliqués. Parmi eux, le facteur eIF3 interagit directement avec celle-ci. Au cours de mes travaux, j'ai étudié dans une première partie l'interaction putative entre le facteur eIF3 et la petite sous-unité ribosomique 40S. Le ribosome est constitué par deux types d'entités : des protéines ribosomiques et l'ARNr. Le facteur eIF3, contient au moins 13 sous-unités, dont deux possèdent un RRM, et sont potentiellement capables de lier cet ARNr via leur RRM: p44 et p116. eIF3p44 a montré auparavant qu'elle pouvait lier l'ARNr 18S. J'ai effectué un criblage d'une banque de fragments de cet ARNr pour identifier un site de liaison de p44 sur la sous-unité 40S. Les ARNm néo-synthétisés sont transportés et localisés afin de permettre l'expression des protéines au moment opportun et en un lieu précis de la cellule. Dans une deuxième partie, j'ai étudié des interactions impliquées dans le contrôle de l'initiation de la traduction d'un ARNm localisé chez la levure S. cerevisiae pendant son transport : l'ARNm ASH1. Il est régulé par Khd1p, protéine à trois domaines KH, qui lie directement un de ses éléments de localisation. Cette interaction est abolie par la phosphorylation de Khd1p lorsque l'ARNm est correctement localisé.

Made available in DSpace on 2016-05-19T13:08:21Z (GMT). No. of bitstreams: 2 173.pdf: 1047808 bytes, checksum: 48de5cc0086090a92e066047b4e59660 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2014 / Fundação Oswaldo Cruz. Centro de Pesquisas Aggeu Magalhães. Recife, PE, Brasil / Os tripanossomatídeos possuem uma combinação não usual de mecanismos moleculares, e seus processos de regulação de expressão gênica ocorreram a nível pós-transcricional. Acredita-se que essa regulação envolva tanto o controle da estabilidade dos mRNAs, como sua tradução em proteínas, eventos em que atua a proteína de ligação à cauda poli-A (PABP - Poly-A Binding Protein), uma das principais proteínas de ligação a RNAs em eucariotos. Um grande número destas proteínas está presente nos tripanosomatídeos, se caracterizando por possuírem domínios típicos de ligação a RNA, como o domínio RRM (RNA Recognition Motif). Dentre estas se destacam as proteínas de ligação a sequências ricas em uridina (UBPs), que se mostraram capazes de interagir com homólogos de PABP. Outras proteínas hipotéticas contendo domínios de ligação a RNA foram identificadas em ensaios que buscavam parceiros diferenciais para os três homólogos de PABP de Leishmania. Este trabalho se propôs a contribuir na caracterização funcional das proteínas UBPs e das proteínas hipotéticas, através da otimização de sua expressão de forma heteróloga em L. infantum, fusionadas ao epítopo HA. Para isto, os genes codificantes dos três homólogos de UBPs, e de cinco outras proteínas de ligação a RNA que parecem interagir com PABPs, foram amplificados e clonados em vetor de expressão de Leishmania. As construções geradas foram transfectadas em L. infantum e a expressão de seis destas proteínas avaliada. Os resultados obtidos mostram uma variação no reconhecimento das proteínas geradas com anticorpos comerciais anti-HA, que parecem depender da sequência de aminoácidos da sua extremidade C-terminal. Diferenças significativas nos seus níveis de expressão também foram observadas. Entre os três homólogos de UBP, dois destes se mostraram mais abundantes enquanto que os três são representados por mais de uma banda, indicando possíveis modificações pós-traducionais