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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.
321

Theta-duality in abelian varieties and the bicanonical map of irregular varieties

Lahoz Vilalta, Marti 18 May 2010 (has links)
The first goal of this Thesis is to contribute to the study of principally polarized abelian varieties (ppav), especially to the Schottky and the Torelli problems. Ppav admit a duality theory analogous to that of projective spaces, where the role played by hyperplanes in projective spaces is played by divisors representing the principal polarization. Thus, given a subvariety Y of a ppav, we can define its thetadual T(Y) as the set of divisors representing the principal polarization that contain this subvariety. This set admits a natural schematic structure (as defined by Pareschi and Popa). Jacobian and Prym varieties are classical examples of ppav constructed from curves. Besides, they are interesting because some properties of the curves involved in their construction are reflected in their geometry or in the geometry of some special subvarieties. For example, in the case of Jacobians we have the BrillNoether loci Wd ( W1 corresponds to the AbelJacobi curve) and in the case of Pryms we have the AbelPrym curve C. In chapter III, we study the schematic structure of the thetadual of the BrillNoether loci Wd and the AbelPrym curve. In the first case, we obtain with different methods, the result of Pareschi and Popa T(Wd)= Wgd1. In the case of the AbelPrym curve C, we get that T(C)=V², where V² is the second PrymBrillNoether locus with the schematic structure defined by Welters. Pareschi and Popa have proved a result for ppavs analogous to the Castelnuovo Lemma for projective spaces. That is, if (A,Θ) is a ppav of dimension g, then g+2 distinct points in general position with respect to Θ, but in special position with respect to 2Θ, have to be contained in a curve of minimal degree in A, i.e. an AbelJacobi curve. In particular, they obtain a Schottky result because A has to be a Jacobian variety and a Torelli result, because the curve is the intersection of all the divisors in |2Θ| that contain the g+2 points. In chapter IV, as Eisenbud and Harris have done in the projective Castelnuovo Lemma, we extend this result to possibly nonreduced finite schemes. The second goal of this thesis is the study of varieties of general type. Almost by definition, pluricanonical maps are the essential tool to study them. One of the main problems in this area is to find geometric or numerical conditions to guarantee that the mth pluricanonical map (for low m) induces a birational equivalence with its image. The classification of surfaces whose bicanonical map is nonbirational has attracted considerable interest among algebraic geometers. In chapter V, we give a sufficient numerical condition for the birationality of the bicanonical map of irregular varieties of arbitrary dimension. We also prove that, if X is a primitive variety, then it only admits very special fibrations to other irregular varieties. For primitive varieties we get that the following are equivalent: X is birational to a divisor Θ in an indecomposable ppav, the irregularity q(X) > dim X and the bicanonical map is nonbirational. When X is a primitive variety of general type and q(X) = dim X we prove, under certain conditions over the Stein factorization of the Albanese map, that the only possibility for the bicanonical map being nonbirational is that X is a double cover branched along a divisor in |2Θ|. These results extend to arbitrary dimension, wellknown theorems in the case of surfaces and curves. / El primer objectiu d'aquesta tesi és contribuir a l'estudi de les varietats abelianes principalment polaritzades (vapp), especialment als problemes de Schottky i Torelli. Les vapp admeten una teoria de dualitat anàloga a la dualitat dels espais projectius, on el paper que juguen els hiperplans de l'espai projectiu és substituït pels divisors que representen la polarització principal. Així doncs, donada una subvarietat Y d'una vapp, podem definir el seu thetadual T(Y) com el conjunt dels divisors que representen la polarització principal i contenen aquesta subvarietat. Aquest conjunt admet una estructura esquemàtica natural (tal i com la defineixen Pareschi i Popa). Les varietats Jacobianes i de Prym són exemples clàssics de vapp construïdes a partir de corbes. A més, són interessants perquè certes propietats de les corbes involucrades es veuen reflectides en elles o en algunes subvarietats especials. Per exemple, en el cas de les Jacobianes tenim els llocs de BrillNoether Wd ( W1 correspon a la corba d'AbelJacobi) i en el cas de les Pryms tenim la corba d'AbelPrym C. Al capítol III de la tesi s'estudia l'estructura esquemàtica del thetadual dels llocs de BrillNoether Wd i de la corba d'AbelPrym. En el primer cas, es reobté amb uns altres mètodes, el resultat de Pareschi i Popa T(Wd)= Wgd1. En el cas de la corba d'AbelPrym C, s'obté que T(C)=V², onV² és el segon lloc de PrymBrillNoether amb l'estructura esquemàtica definida per Welters. Pareschi i Popa han demostrat un resultat anàleg per les vapp al Lemma de Castelnuovo pels espais projectius. És a dir, si (A,Θ) és una vapp de dimensió g, aleshores g+2 punts en posició general respecte Θ, però en posició especial respecte 2Θ, han d'estar continguts en una corba de grau minimal a A, i.e. una corba d'AbelJacobi. En particular, s'obté un resultat de Schottky ja que A ha de ser una Jacobiana i un resultat de Torelli, ja que la corba és la intersecció de tots els divisors de |2Θ| que contenen els g+2 punts. Al capítol IV, tal i com Eisenbud i Harris van fer en el cas projectiu, s'estén aquest resultat a esquemes finits possiblement no reduïts. El segon objectiu d'aquesta tesi és contribuir a l'estudi de les varietats de tipus general. Pràcticament per definició, les aplicacions pluricanòniques són essencials pel seu estudi. Un dels problemes principals de l'àrea és donar condicions geomètriques o numèriques per assegurar que la mèsima aplicació pluricanònica (per m baix) indueix una equivalència biracional amb la imatge. La classificació de les superfícies que tenen l'aplicació bicanònica no biracional ha atret l'atenció de molts geòmetres algebraics. Al capítol V, es dóna un criteri numèric suficient per assegurar la biracionalitat de l'aplicació bicanònica de les varietats irregulars de dimensió arbitrària. També es demostra que si X és una varietat primitiva, aleshores només admet fibracions molt especials a altres varietats irregulars. Per aquestes varietats s'obté que és equivalent que X sigui biracional a un divisor Θ en una vapp indescomponible, a què la irregularitat q(X) > dim X i l'aplicació bicanònica sigui no biracional. Quan X és una varietat primitiva de tipus general i q(X) = dim X es demostra sota certes condicions de la descomposició de Stein del morfisme d'Albanese, que l'única possibilitat per tal que l'aplicació bicanònica sigui no biracional és que X sigui un recobriment doble sobre una vapp ramificat al llarg d'un divisor a |2Θ|. Aquest resultats estenen a dimensió arbitrària, teoremes ben coneguts en el cas de superfícies i corbes.
322

Systèmes dynamiques discrets avec frottement et Identification en biomécanique

Bastien, Jérôme 18 September 2013 (has links) (PDF)
Ce mémoire est consacré à l'étude de systèmes dynamiques discrets avec frottements et à des problèmes d'identification en biomécanique. La première partie concerne des résultats théoriques d'unicité, de convergence et d'analyse numérique de solutions d'équations différentielles non linéaires pour étudier des modèles dynamiques discrets contenant des non-linéarités. Ces non-linéarités sont introduites pour prendre en compte des modèles de frictions via des inclusions différentielles maximales monotones, essentiellement en dimension finie. De nombreux exemples ainsi que des applications sont fournis avec des simulations numériques. La seconde partie est consacrée à la résolution de certains problèmes d'identification en biomécanique : identification d'espaces de travail, de paramètres cinématiques lors de la modélisation de certains mouvements et de paramètres anthropométriques dans le cadre de la dynamique inverse.
323

Performance analysis of wireless relay systems

Vien, Hoai Nam 15 June 2010 (has links)
There has been phenomenal interest in applying space-time coding techniques in wireless communications in the last two decades. In general, the benefit of applying space-time codes in multiple-input, multiple-output (MIMO) wireless channels is an increase in transmission reliability or system throughput (capacity). However, such a benefit cannot be obtained in some wireless systems where size or other constraints preclude the use of multiple antennas. As such, wireless relay communications has recently been proposed as a means to provide spatial diversity in the face of this limitation. In this approach, some users or relay nodes assist the transmission of other users information. This dissertation contributes to the advancement of wireless relay communications by investigating the performance of various relaying signal processing methods under different practical fading environments. In particular, it examines two main relaying methods, namely decode-and-forward (DF) and amplify-and-forward (AF).<p> For DF, the focus is on the diversity analysis of relaying systems under various practical protocols when detection error at relays is taken into account. In order to effectively mitigate the phenomenon of error propagation, the smart relaying technique proposed by Wang et al. in [R1] is adopted. First, diversity analysis of a single-relay system under the scenario that only the relay is allowed to transmit in the second time slot (called Protocol II) is carried out. For Nakagami and Hoyt generalized fading channels, analytical and numerical results are provided to demonstrate that the system always obtains the maximal diversity when binary phase shift keying (BPSK) modulation is used. Second, a novel and low-complexity relaying system is proposed when smart relaying and equal gain combing (EGC) techniques are combined. In the proposed system, the destination requires only the phases of the channel state information in order to detect the transmitted signals. For the single-relay system with M-ary PSK modulation, it is shown that the system can achieve the maximal diversity under Nakagami and Hoyt fading channels. For the K-relay system, simulation results suggest that the maximal diversity can also be achieved. Finally, the diversity analysis for a smart relaying system under the scenario when both the source and relay are permitted to transmit in the second time slot (referred to as Protocol I) is presented. It is shown that Protocol I can achieve the same diversity order as Protocol II for the case of 1 relay. In addition, the diversity is very robust to the quality of the feedback channel as well as the accuracy of the quantization of the power scaling implemented at the relay.<p> For AF, the dissertation considers a fixed-gain multiple-relay system with maximal ratio combining (MRC) detection at the destination under Nakagami fading channels. Different from the smart relaying for DF, all the channel state information is assumed to be available at the destination in order to perform MRC for any number of antennas. Upperbound and lowerbound on the system performance are then derived. Based on the bounds, it is shown that the system can achieve the maximal diversity. Furthermore, the tightness of the upperbound is demonstrated via simulation results. With only the statistics of all the channels available at the destination, a novel power allocation (PA) is then proposed. The proposed PA shows significant performance gain over the conventional equal PA.
324

Finite dimensional stochastic differential inclusions

Bauwe, Anne, Grecksch, Wilfried 16 May 2008 (has links) (PDF)
This paper offers an existence result for finite dimensional stochastic differential inclusions with maximal monotone drift and diffusion terms. Kravets studied only set-valued drifts in [5], whereas Motyl [4] additionally observed set-valued diffusions in an infinite dimensional context. In the proof we make use of the Yosida approximation of maximal monotone operators to achieve stochastic differential equations which are solvable by a theorem of Krylov and Rozovskij [7]. The selection property is verified with certain properties of the considered set-valued maps. Concerning Lipschitz continuous set-valued diffusion terms, uniqueness holds. At last two examples for application are given.
325

Performance Analysis of Diversity Techniques for Wireless Communication System

ISLAM, MD. JAHERUL January 2012 (has links)
Different diversity techniques such as Maximal-Ratio Combining (MRC), Equal-Gain Combining (EGC) and Selection Combining (SC) are described and analyzed. Two branches (N=2) diversity systems that are used for pre-detection combining have been investigated and computed. The statistics of carrier to noise ratio (CNR) and carrier to interference ratio (CIR) without diversity assuming Rayleigh fading model have been examined and then measured for diversity systems. The probability of error (p_e) vs CNR and (p_e) versus CIR have also been obtained. The fading dynamic range of the instantaneous CNR and CIR is reduced remarkably when diversity systems are used [1]. For a certain average probability of error, a higher valued average CNR and CIR is in need for non-diversity systems [1]. But a smaller valued of CNR and CIR are compared to diversity systems. The overall conclusion is that maximal-ratio combining (MRC) achieves the best performance improvement compared to other combining methods. Diversity techniques are very useful to improve the performance of high speed wireless channel to transmit data and information. The problems which considered in this thesis are not new but I have tried to organize, prove and analyze in new ways.
326

Quantifying the Ergonomic Impact on Healthcare Workers Using a Needle-free Injector Device

Olivero Lara, Humberto Jose 01 January 2013 (has links)
Background: Jet injectors are advantageous over needle injectors by eliminating sharps hazards. The Government Accountability Office estimates 29% preventable sharp injuries with an estimated direct cost of more than $500 million out of the CDC's reported incidence of 385,000 needle stick injuries per year among US hospital healthcare workers. Yet the forces required to set and trigger devices using spring mechanisms for medication delivery have not been explored. This laboratory experiment measured forces exerted by healthcare workers (HCWs) using a particular jet injector approved by FDA in 2011. Objectives: In order to quantify the ergonomic impact on HCWs using a needle-free injector, the first objective was to evaluate the dynamic forces required to activate the trigger injector button and the reset station for the injector, with their respective means, for each of the parameters studied. The second objective was to compare these forces to those required to use four previously analyzed retractable intramuscular syringes with needles. Finally, the third objective was to assess potential psychophysics ergonomic impact on HCWs with use of these devices to formulate future design changes and recommendations for manufacturers and HCWs, respectively. Methods: This laboratory experiment was conducted through a multi-disciplinary team approach. It included a total of 136 trials (10 validation trials, 116 experimental trials and 10 padded trials for soft tissue simulation), which were conducted using the PharmaJetTM Injector. A force gauge and a load cell were integrated into the triggering setup and reset station, correspondingly, enabling force measurements to be obtained directly from the human-machine interfaces. These force data allowed for observations of force profiles in time by the healthcare worker as researcher while preparing for and administering injections. Data collection used three software applications for force conversions and data manipulation. Data were analyzed using descriptive statistics and analytical results by using ANOVA for the trigger injector & reset station with multiple comparison tests for parametric and non-parametric distributions, respectively. Results: The descriptive results indicated an average force for triggering the injector in the 116 trials was 15.92 lbs. (70.8 N) with a range of 9.77-26.46 lbs. (43.46-117.69 N). The measured forces for the reset station ranged from 5.35-82.78 lbs. (5.35-368.22 N) with an average of 25.32 lbs. (112.62 N) (SD 12.36). Spurious findings presented with tensile forces to fill the syringes resulting in hand strain in the first metacarpal joint after repetitive pinprick motion. The analytical results showed an ANOVA for trigger injector with a parametric-normal distribution with an F (2,133) Ratio 10.0472, p- value (F) 0.0001<0.05, showing statistical significance and with a Tukey's comparison test showing a significant difference in between the means of the padded trials vs. the validation & experimental trial groups. The ANOVA for the reset station showed a Kruskal Wallis H-statistic of 0.2568, p-value (H) 0.8795>0.05 presenting NO statistical significance with a Dunn's comparison test confirming NO difference in between the medians or mean ranks of all three groups. Conclusions: Triggering the injector and resetting the station required considerable effort in comparison to activating 4 retractable intramuscular syringes with needles from our previous studies, the range of mean forces were 3.63-17 lbs (16.19-77.53 N) for those syringes with the trigger injector maximum voluntary force of 71 N being above the recommend 56.6 N.The jet injector required more force per effort than 2 (4.4x) syringes & similar to other 2 syringes (0.9x) previously tested when considering the compression forces related with the trigger injector. Additional vector forces (displacement & gripping of reset station) could increase the cumulative effort affecting different musculoskeletal components when the whole components of the procedure are taken into account. Suggestions for the manufacturer regarding design changes to facilitate HCWs' use of this device are warranted, since some of the summation forces during the 12 mini-steps could be avoided to achieve a higher efficiency. This information may be useful for health care facilities when choosing devices to protect their workers from ergonomic injuries.
327

The effects of carbohydrate-protein supplementation on endurance exercise performance, recovery, and training adaptation

Stegall, Lisa Ferguson 07 February 2011 (has links)
Recent research suggests that adding protein (PRO) to a carbohydrate (CHO) supplement can have substantial benefits for endurance exercise performance and recovery beyond that of CHO alone. CHO+PRO supplements are often commercially available formulations consisting of carbohydrates (dextrose, maltodextrin) and whey protein. The effects of a supplement containing moderate protein and a low-CHO mixture on endurance performance has not been investigated. Also, the effects of CHO+PRO supplementation in the form of a natural food, flavored milk, on measures of recovery from acute endurance exercise, as well as on chronic aerobic exercise training adaptations, have not been characterized. Therefore, in this series of four studies, the effects of CHO+PRO supplementation on the following areas of endurance exercise performance, recovery, and adaptation are investigated: acute endurance exercise performance, inflammatory and muscle damage markers, muscle glycogen resynthesis, activation of signaling proteins involved in the initiation of protein synthesis and degradation, subsequent endurance exercise performance, and chronic aerobic training adaptations (maximal oxygen consumption, oxidative enzyme activity, body composition, immune cell levels, and inflammatory markers). Study 1 demonstrated that a supplement containing a low-CHO mixture plus moderate protein significantly improved aerobic endurance when cycling at or below the ventilatory threshold, despite containing 50% less CHO and 30% fewer calories relative to a higher CHO beverage. Study 2 demonstrated that CHO+PRO supplementation in the form of chocolate milk (CM) is an effective post-exercise supplement that can improve subsequent performance and provide a greater intracellular signaling stimulus for protein synthesis compared to CHO and placebo. Study 3 found that post-exercise CM supplementation during 4.5 wks of aerobic exercise training improves the magnitude of cardiovascular adaptations more effectively than isocaloric CHO or placebo, while the fourth study demonstrated that post-exercise CM supplementation during 4.5 wks of aerobic training improves body composition more effectively than isocaloric CHO or placebo. The fourth study also demonstrated that 4.5 wks of training does not appear to perturb resting immune cell concentrations or markers of inflammation and muscle damage. Taken together, the results of this research series suggest that CHO+PRO supplementation extends endurance performance, improves recovery, and increases training adaptations more effectively than CHO or placebo. / text
328

Αποδοτική διαχείριση κειμενικής πληροφορίας, δεικτοδότηση, αποθήκευση, επεξεργασία και εφαρμογές

Θεοδωρίδης, Ευάγγελος 03 July 2009 (has links)
Βασική επιδίωξη της παρούσας διατριβής είναι η διερεύνηση των δυνατοτήτων του πεδίου της επιστήμης των υπολογιστών που πραγματεύεται την αποθήκευση και την επεξεργασία πληροφορίας, μέσα στο περιβάλλον που έχουν σχηματίσει οι σύγχρονες εφαρμογές. Τα τελευταία χρόνια, η πληροφορία που είναι διαθέσιμη σε ηλεκτρονική μορφή, έχει γιγαντωθεί με αποτέλεσμα να είναι αναγκαία η ανάπτυξη νέων τεχνικών για την αποτελεσματική αποθήκευση και επεξεργασία αυτής. Δύο πολύ χαρακτηριστικές και σημαντικές εφαρμογές, στις οποίες ανακύπτουν συνεχώς νέα προβλήματα, είναι η διαχείριση Βιολογικών δεδομένων, όπως π.χ. οι ακολουθίες γονιδιωμάτων, καθώς και η διαχείριση πληροφορίας από τον παγκόσμιο ιστό, όπως π.χ. τα έγγραφα HTML, XML ή οι συντομεύσεις (urls). Στόχος είναι ανάπτυξη δομών δεικτοδότησης πάνω στην πληροφορία έτσι ώστε τα σχετικά ερωτήματα με αυτή να απαντώνται αποδοτικά και πολύ πιο γρήγορα από το να ψάχναμε εκτενώς μέσα σε αυτή. Χαρακτηριστικά τέτοια ερωτήματα είναι η εύρεση προτύπων (pattern matching) ή ο εντοπισμός επαναλαμβανόμενων μοτίβων (motif extraction). Πιο συγκεκριμένα, τα ϑέματα στα οποία εστίασε η παρούσα διατριβή είναι τα ακόλουϑα: - Εντοπισμός Περιοδικοτήτων σε συμβολοσειρές. Στην ενότητα αυτή δίνεται μια σειρά από αλγόριθμους για την εξαγωγή περιοδικοτήτων από συμβολοσειρές. Δίνονται αλγόριθμοι για την εξαγωγή μέγιστων επαναλήψεων, της περιόδου του καλύμματος και της ρίζας μιας συμβολοσειράς. Οι αλγόριθμοι αυτοί χρησιμοποιούν ώς βάση το δένδρο επιθεμάτων και οι περισσότεροι από αυτούς είναι γραμμικοί. - Δεικτοδότηση Βεβαρημένων Ακολουθιών. Στην επόμενη ενότητα η μελέτη εστιάζει στην δεικτοδότηση βεβαρημένων ακολουθιών, καθώς και στην απάντηση ερωτημάτων σε αυτές όπως η εύρεση προτύπων, η εύρεση επαναλήψεων, η εύρεση καλυμμάτων, κ.α.. Οι βεβαρημένες ακολουθίες είναι ακολουθίες όπου σε κάθε ϑέση τους έχουμε εμφάνιση όλων των συμβόλων του αλφαβήτου της ακολουθίας, έχοντας λάβει ένα συγκεκριμένο βάρος. Οι βεβαρημένες ακολουθίες αναπαριστούν βιολογικές ακολουθίες είτε νουκλεοτιδίων είτε αμινοξέων και στην ουσία περιγράφουν την πιθανότητα εμφάνισης ενός συμβόλου του αλφαβήτου σε μια συγκεκριμένη ϑέση της ακολουθίας ή κάποιες συγκεκριμένες βιολογικές ιδιότητες που διαθέτουν οι ρυθμιστικές πρωτεΐνες σε κάθε ϑέση της ακολουθίας. Για την διαχείριση αυτών των ιδιόμορφων ακολουθιών προτείνεται ως δομή δεικτοδότησης το βεβαρημένο δένδρο επιθεμάτων (Weighted Suffix Tree), ένα δένδρο με παρόμοια δομικά χαρακτηριστικά με αυτά του γενικευμένου δένδρου επιθεμάτων. Στην παρούσα εργασία δίνεται ο ορισμός του βεβαρημένου δένδρου επιθεμάτων και αλγόριθμοι κατασκευής του σε γραμμικό χρόνο και χώρο. -Εξαγωγή μοτίβων από βεβαρημένες Ακολουθίες. Με την χρήση του βεβαρημένου δένδρου επιθεμάτων υλοποιούνται ένα σύνολο αλγόριθμων εξαγωγής επαναληπτικών δομών από βεβαρημένες ακολουθίες. Πιο συγκεκριμένα, δίνονται αλγόριθμοι για την εύρεση μέγιστων ευγών,επαναλαμβανόμενων μοτίβων και κοινών μοτίβων από περισσότερες της μίας βεβαρημένες ακολουθίες. - Αλγόριθμοι Σύστασης Σελίδων Παγκόσμιου Ιστού με χρήση τεχνικών επεξεργασίας συμβολοσειρών. Αρκετές εφαρμογές παγκόσμιου ιστού (συστήματα σύστασης ή συστήματα κρυφής μνήμης) προσπαθούν να προβλέψουν τις προθέσεις ενός επισκέπτη είτε για να του προτείνουν είτε για να προφορτώσουν μία σελίδα. Για το σκοπό αυτό προσπαθούν να εκμεταλλευτούν οποιαδήποτε εμπειρία που έχει καταγραφεί στο σύστημα από προηγούμενες προσπελάσεις. Προτείνεται νέος τρόπος δεικτοδότησης και αναπαράστασης της πληροφορίας που εξάγεται από τα διαθέσιμα δεδομένα, όπως οι προσβάσεις των χρηστών από τα logfilesκαι το περιεχόμενο των σελίδων. Για την εξόρυξη γνώσης από τα παραπάνω δεδομένα, αυτά αναπαριστώνται ως συμβολοσειρές και στη συνέχεια επεξεργάζονται και δεικτοδοτούνται από ένα γενικευμένο βεβαρημένο δένδρο επιθεμάτων. Το δένδρο αυτό συμπυκνώνει αποδοτικά τα πιο συχνά αλλά και πιο ουσιαστικά μοτίβα προσπελάσεων και χρησιμοποιείται, αφότου κατασκευαστεί, σαν ένα μοντέλο για την πρόβλεψη των κινήσεων τον επισκεπτών ενός ιστοτόπου. / The basic goal of this thesis is to explore the possibilities of the field of computer science that deals with storing and processing information in the environment that formed by the modern applications. In recent years, the information that is available in electronic form, has met an enormous growth. Thus it is necessary to develop new techniques for efficient storage and processing. Two very specific and important applications in which constantly new problems arise are, the management of biological data, such as genome sequences, and the management information from the Web, such as documents HTML, XML or shortcuts (urls). The objective is the development of data structures for indexing information so that the questions are able to be answered in less time than looking explicitly in information. Such questions are to find patterns (pattern matching) or the identification of repeated motifs (motif extraction). In particular, the issues on which this thesis has focused are: - Locating Periodicities in strings. This section provides a series of algorithms for the extraction of periodicities of strings. We propose algorithms for the extraction of maximum repetitions of the cover, period and the seed of a string. The algorithms used are based on suffix tree and they are optimal. - Weighted Sequences indexing. In the next section, the study focuses on indexing of weighted sequences, and to answer questions like finding models, pairs, covers etc. in them. The weighted sequences are sequences where each position consists of all the symbols of the alphabet in sequence, having each one a specific weight. For the management of these sequences a particular indexing structure is proposed with the name Weighted Suffix Tree, a tree with structural features similar to those of the generalized suffix tree. In this work we propose the definition of the weighted suffix tree and construction algorithms in linear time and memory space. With the utilization of weighted suffix tree on a set of weighted sequences we propose algorithms for extracting repetitive structures from a set of weighted sequences. More specifically, we propose algorithms for finding maximum pairs, repeated motifs and common patterns of more than one weighted sequences -Recommendation Algorithms for web pages using strings processing algorithms. Several web applications (Recommendation systems or cache systems) want to predict the intentions of a visitor in order to propose or to preload a webpage. For this purpose systems try to exploit any experience that is recorded in the system from previous accesses. A new method for indexing and representing of information extracted is proposed upon the recorder data, from the user accesses in log files and content pages. For extracting knowledge from these data, the information is represented as strings and then treated and processed as weighted sequences. All these sequences are indexed by a generalized weighted sequence tree.
329

Echocardiographic measurements of the heart : with focus on the right ventricle

Loiske, Karin January 2011 (has links)
Echocardiography is a well established technique when evaluating the size and function of the heart. One of the most common ways to measure the size of the right ventricle (RV) is to measure the RV outflow tract 1(RVOT1). Several ways to measure RVOT1 are described in the literature.These ways were compared with echocardiography on 27 healthy subjects.The result showed significant differences in RVOT1, depending on the way it was measured, concluding that the same site, method and body positionshould be used when comparing RVOT1 in the same subject over time.One parameter to evaluate the RV diastolic function (RVDF) is to measure the RV isovolumetric relaxation time (RV-IVRT), a sensitive marker ofRV dysfunction. There are different ways to measure this. In this thesis two ways of measuring RV-IVRT and their time intervals were compared in 20 patients examined with echocardiography. There was a significant difference between the two methods indicating that they are not measuring the same interval.Another way to assess the RVDF is to measure the maximal early diastolicvelocity (MDV) in the long-axis direction. MDV can be measured bydifferent methods, hence 29 patients were examined and MDV was measured according to two methods. There was a good correlation but a poor agreement between the two methods meaning that reference values cannot be used interchangeably.Takotsubo cardiomyopathy is characterized by apical wall motion abnormalities without coronary stenosis. The pathology of this condition remains unclear. To evaluate biventricular changes in systolic long-axisfunction and diastolic parameters in the acute phase and after recovery, 13 patients were included and examined with echocardiography at admission and after recovery. The results showed significant biventricular improvementof systolic long-axis function while most diastolic parameters remainedunchanged.
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Skirtingo amžiaus rankininkių aerobinio pajėgumo ir kvėpavimo funkcijos ypatumai / Aerobic Capacity and Function of Respiratory System in female handball players of different age

Petruninaitė, Augusta 18 June 2008 (has links)
Tyrimo objektas – didelio meistriškumo rankininkių kvėpavimo sistemos funkcija ir aerobinis pajėgumas. Tyrimo aktualumas. Aerobinis pajėgumas yra labai svarbus rankinyje siekiant aukštų sportinių rezultatų. Kiekvienoje sporto šakoje sportininkai skiriasi savo aerobiniu pajėgumu, todėl mūsų darbas yra aktualus, nes informatyviais tyrimo metodais nustatėme skirtingo amžiaus rankininkių aerobinį pajėgumą ir kvėpavimo sistemos funkcinius rodiklius. Tyrimo problema. Kokią įtaką amžius turi rankininkių aerobiniam pajėgumui bei kvėpavimo sistemos funkcijoms? Tyrimo tikslas: Nustatyti skirtingo amžiaus rankininkių kvėpavimo funkcijos ir aerobinio pajėgumo ypatumus. Uždaviniai: 1. Nustatyti skirtingo amžiaus rankininkių kvėpavimo sistemos pajėgumą ramybėje ir nuosekliai didėjančio fizinio krūvio metu. 2. Nustatyti skirtingo amžiaus rankininkių aerobinį pajėgumą. 3. Palyginti jaunesnio ir vyresnio amžiaus rankininkių aerobinį pajėgumą ir kvėpavimo funkcinius rodiklius. Išvados 1. Jaunesniųjų rankininkių maksimalūs plaučių ventiliacijos rodikliai buvo didesni, tiek testuojant ramybėje (maksimali valinga ventiliacija), tiek ir nuosekliai greitėjančio bėgimo metu (didžiausios pasiektos reikšmės). 2. Absoliučios plaučių talpos reikšmingai nesiskyrė lyginant skirtingo amžiaus rankininkių, tačiau lyginant su atitinkamo amžiaus norminėmis reikšmėmis forsuota iškvėpimo talpa buvo santykinai geresnė vyresnių rankininkių. 3. Jaunesnių rankininkių maksimalus deguonies suvartojimas... [toliau žr. visą tekstą] / The object of research – respiratory system and aerobic capacity of professional female handball players. The relevance of research. The efficiency of aerobic capacity is important in handball play. In every sports athletes differs in aerobic theme capacity, thats why our study is relevant, because we obtained the results about on aerobic capacity of the female handball players in different age group. Question of research – what influence has age for the aerobic capacity and respiratory system function of female handball players. The purpose of research: to determine the respiratory function and aerobic capacity of the professional female handball players of different age. Goals: 1. To determine the capacity of respiratory system of the female handball players. 2. To determine the aerobic capacity of female handball players. 3. To compare the data of senior and junior female hanball players. Conclusions 1. The rates of the maximal lungs ventilation of junior female handball players were greater in both while testing at rest and maximal ventilation continuously accelerating running (maximal achieved value). 2. Absolute lungs capacity did not change significantly between different age female handball players, although comparing the forced exhalation capacity of appropriate age standard value, senior handball players had relatively better data. 3. The maximal oxygen uptake, ventilation threshold and correspondent values of vegetative system (HR, maximal oxygen... [to full text]

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