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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

Développement d'un indice de séparabilité adapté aux données de génomique en analyse de survie

Rouam, Sigrid Laure 30 March 2011 (has links) (PDF)
Dans le domaine de l'oncogénomique, l'un des axes actuels de recherche est l'identification de nouveaux marqueurs génétiques permettant entre autres de construire des règles prédictives visant à classer les patients selon le risque d'apparition d'un événement d'intérêt (décès ou récidive tumorale). En présence de telles données de haute dimension, une première étape de sélection parmi l'ensemble des variables candidates est généralement employée afin d'identifier les marqueurs ayant un intérêt explicatif jugé suffisant. Une question récurrente pour les biologistes est le choix de la règle de sélection. Dans le cadre de l'analyse de survie, les approches classiques consistent à ranger les marqueurs génétiques à partir du risque relatif ou de quantités issues de test statistiques (p-value, q-value). Cependant, ces méthodes ne sont pas adaptées à la combinaison de résultats provenant d'études hétérogènes dont les tailles d'échantillons sont très différentes.Utiliser un indice tenant compte à la fois de l'importance de l'effet pronostique et ne dépendant que faiblement de la taille de l'échantillon permet de répondre à cette problématique. Dansce travail, nous proposons un nouvel indice de capacité de prédiction afin de sélectionner des marqueurs génomiques ayant un impact pronostique sur le délai de survenue d'un évènement.Cet indice étend la notion de pseudo-R2 dans le cadre de l'analyse de survie. Il présente également une interprétation originale et intuitive en terme de " séparabilité ". L'indice est tout d'abord construit dans le cadre du modèle de Cox, puis il est étendu à d'autres modèles plus complexes à risques non-proportionnels. Des simulations montrent que l'indice est peu affectée par la taille de l'échantillon et la censure. Il présente de plus une meilleure séparabilité que les indices classiques de la littérature. L'intérêt de l'indice est illustré sur deux exemples. Le premier consiste à identifier des marqueurs génomiques communs à différents types de cancers. Le deuxième, dans le cadre d'une étude sur le cancer broncho-pulmonaire, montre l'intérêt de l'indice pour sélectionner des facteurs génomiques entraînant un croisement des fonctions de risques instantanés pouvant être expliqué par un effet " modulateur " entre les marqueurs. En conclusion, l'indice proposé est un outil prometteur pouvant aider les chercheurs à identifier des listes de gènes méritant des études plus approfondies.
22

The gendered nature of intra-household decision making in and across Europe

Schneebaum, Alyssa, Mader, Katharina 10 1900 (has links) (PDF)
After surveying the literature on the economics of household decision-making, we employ data from the 2010 European Union Survey on Income and Living Conditions (EU-SILC) to study the relationship between personal characteristics such as gender and decision-making power and responsibility. We find that across Europe, women more often make decisions about everyday spending and purchases for children, while it is mainly men who make the financial decisions in a household. Greater intrahousehold inequality in income and education is correlated with a lower probability of couples making decisions together, as is having a housewife in the home. Interesting patterns of household decision-making across countries emerge; in the Southern European countries, for example, educational differences do not seem to be strongly related to decision-making power and responsibility, and women in Eastern European countries are more likely to make financial decisions when the household reports facing difficult economic conditions. (authors' abstract) / Series: Department of Economics Working Paper Series
23

CTCF Contributes to the Regulation of the Ribosomal DNA in Drosophila melanogaster

Guerrero, Paola 2011 December 1900 (has links)
The 35S rDNA gene clusters on the X and Y chromosomes of Drosophila melanogaster are repeats of approximately 150 to 225 copies. Each are transcribed as a single unit by RNA Polymerase I and modified into the 18S, 5.8S, 2S and 28S ribosomal rRNAs. Reduction in the array copy number results in a bobbed phenotype, characterized by truncated bristles and herniations of abdominal cuticle, due to a decrease in protein production. In some copies within the arrays, R1 and R2 retrotransposable elements are inserted in a conserved region of the 28S gene which represses the transcription of a functional rRNA. Inserted arrays are transcribed at very low levels, but it is not clear how they are identified for repression. Similarly, a subset of uninserted arrays are silenced, and the epigenetic mechanism controlling how this decision is made it is also unknown. The CCCTC binding factor (CTCF) is a boundary element binding protein and a transcriptional regulator found in the nucleolus of differentiated mammalian cells, whose localization requires poly (ADP-ribosyl)ation. We investigated whether CTCF might be involved in the regulation of rDNA expression in Drosophila. Our data show that CTCF is found at the nucleolus of both polytene and diploid nuclei, and we have identified binding sites in the 28S gene, R1 and R2 elements by a bioinformatic approach. ChIP data indicate that CTCF binds only to the site in the R1 retrotransposon. Reduction of CTCF or members of the poly(ADP-ribosyl)ation pathway by RNAi in S2 cells causes an increase in the amount of 35S rDNA gene, R1, and R2 transcripts. In flies, CTCF and PARG mutant alleles show disrupted nucleoli and increased rRNA transcripts. Mutant alleles of CTCF suppress variegation of a P-element inserted in a 35S rDNA array, but not of elements inserted elsewhere in the genome. Consistent with a role for CTCF in rRNA regulation, we found that during oogenesis CTCF is recruited to the nucleolus of nurse cells at early stages when the demand of ribosomes is low and it leaves this compartment in later stages when the cell increases rRNA production. We conclude from these studies that CTCF acts as a regulation of rDNA transcription by RNA polymerase I.
24

Η ερμηνευτική ικανότητα του συντελεστή R-square στον υπολογισμό της αξίας της επιχείρησης

Θεοδωράκη, Χαρίκλεια 01 February 2013 (has links)
Αρκετές μελέτες έχουν στρέψει τη προσοχή τους στη σχέση που συνδέει το R2 με την αξία της επιχείρησης αλλά και στο βαθμό που τα διαφορετικά R2 μπορούν να την επηρεάσουν. Στην παρούσα έρευνα έγινε προσπάθεια να ελεγχθεί η συγκεκριμένη σχέση στις ελληνικές επιχειρήσεις. Για το σκοπό αυτό χρησιμοποιήθηκαν 135 επιχειρήσεις εισηγμένες στο ΧΑ, από το 2004 έως το 2010. Τα αποτελέσματα της εργασίας έδειξαν ότι το R2 συνδέεται με μια αρνητική σχέση με την αξία της επιχείρησης. Τα ευρήματα της έρευνας συμφωνούν με το μοντέλο των Dow and Gorton (1997). Επίσης, βρέθηκε ότι μακροχρόνια οι εταιρείες με υψηλό R2 τείνουν να έχουν υψηλότερες αποδόσεις. / Several studies have focused on the relationship between the R2 and the firm value. They also pay attention on the consequences of the different values of R2 between sectors. In this paper we examine this relationship for the Greek companies listed in the stock exchange. For this purpose, we use a sample consisted of 135 listed companies for the period 2004-2010. The results of this study reveal that R2 is inversely associated with the firm value. This is consistent with the model of Dow and Gorton (1997). Also we found that companies with high R2 have significantly higher returns from the companies with low R2, over a two year period time.
25

EN JÄMFÖRELSE AV BERÄKNINGSNODER AVSEENDE ENERGIEFFEKTIVITET OCH FÖRMÅGAN ATT BERÄKNA FLYTTALSOPERATIONER I ETT MICROSOFT HPC-KLUSTER

Kronlund, Marcus January 2012 (has links)
Beräkningskluster används exempelvis till vädersimuleringar eller produktsimulering. Microsoft HPC-kluster tillhandahåller två olika typer av beräkningsnoder var av den ena är Computenod, som körs med operativsystemet Windows Server 2008 R2, och den andra är Workstationnod, som körs med operativsystemet Windows 7. Arbetets syfte är att jämföra operativsystemen Windows 7 och Windows Server 2008 R2 för att se om de presterar likartat som en beräkningsnod. Detta avgörs med avseende på energieffektivitet samt hur de presterar i Linpack. Linpack är ett prestandaverktyg som mäter ett beräkningsklusters beräkningsförmåga i flyttalsoperationer per sekund. Studien utförs genom en experimentell metod. Några studier om att operativsystemen Windows 7 och Windows Server 2008 R2 presterar likartat finns inte. Därför motiveras det till att verifiera hypotesen att de ska prestera likartat inom beräkningskluster. Eftersom båda operativsystemen är byggda på Windows NT 6.1, bör de prestera likartat (Microsoft msdn, 2012). Studier av Narayan och Shi (2009, 2010) visar att operativsystem presterar olika med TCP och UDP protokollen. De visar även att operativsystemen presterar olika på applikationslagret. En annan studie av Abouelhoda och Mohamed (2009) visar att valet av operativsystem påverkar resultaten för deras testverktyg, WinBioinfTools. Testverktyget utvärderades på Linux-kluster och Microsoft HPC-kluster. Sottile och Minnich (2004) visar i sin studie att beräkningsförmågan påverkas av operativsystemen. Bidraget för denna studie är att administratörer ska kunna använda resultaten som underlag när de ska motivera valet av vilken typ av beräkningsnod som ska väljas till ledningen i organisationer eller företag. Resultatet visar att operativsystemen presterar ungefär lika efter att vissa processer har stängts av i Windows 7. De processer som stängts av körs inte på operativsystemet Windows Server 2008 R2 utan endast på Windows 7. En slutsats som dras är att processerna som körs påverkar resultaten. Processerna bör därför stängas av om de inte är nödvändiga för företaget eller organisationen. Stängs onödiga processer av, ökar energieffektiviteten och prestandan för beräkningsklustret vilket medför att bidraget till den globala uppvärmningen minskar eftersom energin går åt till att beräkna uppgifterna och inte onödiga processer.
26

Utveckling av webbaserad Outlookklient kopplad mot Exchangeserver

Holten, Pär January 2012 (has links)
Ett nystartat företag ville skapa en hemsida som såg ut och fungerade som Outlook.  Denna sida skulle senare kunna kopplas till Exchange eller något liknande e-postserverprogram. Under arbetets gång så installerades en labbserver med Exchange. När servern var färdig så skulle det gå att koppla upp företaget Teleriks webmaillösning för att sedan kolla om den klarar av Exchange. Målet var att en sida liknande Outlook, till utseende samt funktion, skulle skapas. Denna sida skulle sedan kopplas ihop med en fungerande Exchange server. En fungerande Exchange server samt hemsida kopplades ihop men det uppstod problem då betrott certifikat saknades/fungerade inte.
27

Untersuchungen von Phospho-AMPK α, VEGF-A und VEGF-R2 im Myokard sowie Analysen von morphologischen Veränderungen im Modell der chronischen Herzinsuffizienz induziert durch sequentielle, repetitive koronare Mikroembolisation an der Spezies Schaf / Analyses of Phospho-AMPK α, VEGF-A , VEGF-R2 in myocardium and investigations in morphological changes in a model of chronic heart failure induced by multiple sequential coronary microembolization in sheep

Heidrich, Florian 04 October 2011 (has links)
No description available.
28

Analytisk Studie av Avancerade Gradientförstärkningsalgoritmer för Maskininlärning : En jämförelse mellan XGBoost, CatBoost, LightGBM, SnapBoost, KTBoost, AdaBoost och GBDT för klassificering- och regressionsproblem

Wessman, Filip January 2021 (has links)
Maskininlärning (ML) är idag ett mycket aktuellt, populärt och aktivt forskat område. Därav finns det idag en stor uppsjö av olika avancerade och moderna ML-algoritmer. Svårigheten är att bland dessa identifiera den mest optimala att applicera på ens tillämpningsområde. Algoritmer som bygger på Gradientförstärkning (eng. Gradient Boosting (GB)) har visat sig ha ett väldigt brett spektrum av appliceringsområden, flexibilitet, hög förutsägelseprestanda samt låga tränings- och förutsägelsetider. Huvudsyftet med denna studie är på klassificerings- och regressiondataset utvärdera och belysa prestandaskillnaderna av 5 moderna samt 2 äldre GB-algoritmer. Målet är att avgöra vilken av dessa moderna algoritmer som presterar i genomsnitt bäst utifrån på flera utvärderingsmått. Initialt utfördes en teoretisk förstudie inom det aktuella forskningsområdet. Algoritmerna XGBoost, LightGBM, CatBoost, AdaBoost, SnapBoost, KTBoost, GBDT implementerades på plattformen Google Colab. Där utvärderades dess respektive, tränings- och förutsägelsestid samt prestandamåtten, uppdelat i ROCAUC och Log Loss för klassificering samt R2 och RMSE för regression. Resultaten visade att det generellt var små skillnader mellan dom olika testade algoritmerna. Med undantag för AdaBoost som i allmänhet, med större marginal, hade den sämsta prestandan. Därmed gick det inte i denna jämförelse utse en klar vinnare. Däremot presterade SnapBoost väldigt bra på flera utvärderingsmått. Modellresultaten är generellt sätt väldigt begränsade och bundna till det applicerade datasetet vilket gör att det överlag är väldigt svårt att generalisera det till andra datauppsättningar. Detta speglar sig från resultaten med svårigheten att identifiera ett ML-ramverk som utmärker sig och presterar bra i alla scenarier. / Machine learning (ML) is today a very relevent, popular and actively researched area. As a result, today there exits a large numer of different advanced and modern ML algorithms. The difficulty is to identify among these the most optimal to apply to one’s area of application. Algorithms based on Gradient Boosting (GB) have been shown to have a very wide range of application areas, flexibility, high prediction performance and low training and prediction times. The main purpose of this study is on classification and regression datasets evaluate and illustrate the performance differences of 5 modern and 2 older GB algorithms. The goal is to determine which of these modern algorithms, on average, performs best on the basis of several evaluation metrics. Initially, a theoretical feasibility study was carried out in the current research area. The algorithms XGBoost, LightGBM, CatBoost, AdaBoost, SnapBoost, KTBoost, GBDT were implemented on the Google Colab platform. There, respective training and prediction time as well as the performance metrics were evaluated, divided into ROC-AUC and Log Loss for classification and R2 and RMSE for regression. The results showed that there were generally small differences between the different algorithms tested. With the exception of AdaBoost which in general, by a larger margin, had the worst performance. Thus, it was not possible in this comparison to nominate a clear winner. However, SnapBoost performed very well in several evaluation metrics. The model results are generally very limited and bound to the applied dataset, which makes it generally very difficult to generalize it to other data sets. This is reflected in the results with the difficulty of identifying an ML framework that excels and performs well in all scenarios.
29

Unterschiedliche Wirkungen der TNF-alpha-Rezeptoren auf De- und Regeneration peripherer NervenEine Studie an TNF-alpha-Rezeptor-Knockoutmäusen in zwei verschiedenen Tiermodellen für Nervenläsionen / Different effects of TNF-alpha-receptors on de- and regeneration of the peripheral nerveA study in TNF-alpha-receptor-knockout-mice in two different models of nerve injury

Stallforth, Sabine January 2007 (has links) (PDF)
Noch immer ist die Behandlung von Neuropathien mit den gängigen therapeutischen Mitteln für viele Patienten sehr unbefriedigend. Als erfolgsversprechender therapeutischer Ansatz werden zur Zeit Wege erforscht, welche direkt in die molekularen Entstehungsmechanismen pathologischer Veränderungen und regenerationsfördernder Mechanismen eingreifen, um dadurch eine Heilung von Nervenschäden zu ermöglichen. Bisher sind die Erkenntnisse über diese Mechanismen nicht vollständig genug, um daraus eine sichere Behandlungsmöglichkeit abzuleiten. Wegweisende Erkenntnisse deuten sich allerdings durch Studien von unterschiedlichen Vertretern des Zytokinnetzwerkes an - darunter auch TNF-alpha - welche als molekulare Ursache neuropathischer Veränderungen diskutiert werden. In dieser Studie wurde an Knockoutmäusen der Einfluss des jeweiligen TNF-alpha-Rezeptors auf morphologische Veränderungen nach CCI (Chronic constriction injury) und Crush-Verletzung des N. ischiadicus untersucht. Nach 3,7,15 und 36 Tagen (CCI) bzw. 3,7 und 28 Tagen (Crush) wurden in Methylenblau gefärbten Semidünnschnitten intakte und degenerierte Nervenfasern, Makrophagen, Angioproliferation, Ödembildung udn Veränderung des Anteils nicht neuronaler Zellen lichtmikroskopisch beurteilt. Zusätzlich wurden Mac-1+ Makrophagen immunzytochemisch erfasst. Die Ergebnisse zeigten in beiden Modellen und bei beiden Knockouttypen eine starke axonale Schädigung, die von einer großen endoneuroalen Makrophagenansammlung begleitet war. Bei TNF-R1-/- Mäusen war eine stärkere und verlängerte Degeneration mit entsprechend höheren Makrophagenzahlen sichtbar. In den Immunzytochemischen Färbungen wiesen die TNF-R1-/- Mäuse hingegen den geringsten Makropahgenanteil auf.Trotz der starken Schädigung war die anschließende Regeneration im Gegensatz zu WT und TNF-R2-/- Mäusen besser. Die Ödembildung war bei den TNF-R2-/- nach CCI besonders stark ausgeprägt und von einer schlechten Regeneration gefolgt. Während die gefundenen Daten auf eine Beteiligung beider Rezeptoren während degenerativer Prozesse hindeuten, scheint insbesondere TNF-R2 regenerationsfördernde Effekte zu vermitteln. / Current Treatment of neuropathic disorders is still dissatisfactory for many patients. A promising approach is the investigation of agents that directly interfere with molecular development of pathologic changes and regeneration. Up to now, consolidated findings of the underlying mechanisms are not yet sufficent to allow therapeutic intervention. Pathbreaking findings come from studies investigating different agents of the cytokine network - as e.g. TNF-alpha - that are discussed as molecular cause of neuropathic changes. This study investigated the influence of both TNF-alpha-receptors on morphologic changes after CCI (chronic constriction injury) and crush-injury of the sciatic nerve of TNF-R-knockoutmice. After 3,7,15 and 36 days (CCI), and 3,7 and 28 respectively (Crush),intact and degenerating nerve fibers, macrophages, angioproliferation, development of edema and changes in the amount of non-neuronal cells were acquired by light microscopy of toluidin-stained semithin sections. Additionally Mac-1+ macrophages were acquired via immuncytochemically stained sections. The results showed strong axonal damage in both knockout-types accompanied by large amounts of endoneurial macrophages. TNF-R1-/-mice showed a longer degeneration phase including respectively higher amounts of macrophages. In contrast the TNF-R1-/-mice revealed the fewest amount of macrophages in immunocytochemical sections. Despite the strong damage better nerve regeneration was observed compared to WT and TNF-R2-/-mice. Formation of edema was pronounced in TNF-R2-/- after CCI and followed by poorly regeneration. Whereas these findings point to a participation of both receptors in degeneration, TNF-R2 seems to support regeneration.
30

Využití mapových podkladů při řešení reportingu / Use of maps in reporting

Huňa, Tomáš January 2011 (has links)
The main objective of this thesis is to describe working with spatial data and their use in reports. The author focuses mainly on the MS SQL Server 2008 R2 platform. The first part deals with theoretical foundations. Defines the concept of Location Intelligence and describes its history to the present. It also addresses the benefits of Location Intelligence in various sectors and the relationship with Business Intelligence. Further theoretical part goes on to describe both spatial data at a general level and at the level of MS SQL Server 2008 R2. In addition, it described the use of ESRI Shapefile files and work with these files. From the description of spatial data author goes on to use reporting tools in Microsoft - SQL Server Reporting Services and Report Builder. Possible forms of map visualization and a detailed description of the settings are at the end of the theoretical part. The second part is focused on solving practical problems. Tools that are described in the theoretical part, are used to create report examples that the author at the beginning of this section set out to create.

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