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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.
311

Indicadores de qualidade física e química de solo em sistemas de pecuária extensiva no Cerrado Brasileiro /

Tavanti, Renan Francisco Rimoldi January 2020 (has links)
Orientador: Rafael Montanari / Resumo: A qualidade do solo não é algo que se pode medir diretamente, no entanto, pode ser avaliada pelos atributos que caracterizam seu estado físico, químico e biológico. A escolha de atributos mais relevantes e a interpretação das medidas obtidas não é algo simples, devido aos efeitos da mudança de uso da terra e as interações entre eles e as condições climáticas e serviços ecossistêmicos de cada região. O objetivo desse estudo foi fornecer uma visão geral de alguns indicadores de qualidade física e química do solo no contexto de restauração de pastagens do Cerrado Brasileiro. A tese é disposta em capítulos, compondo além das considerações gerais apresentadas no Capítulo 1, os Capítulos 2 e 3, que são estudos científicos de avaliação da qualidade física e química do solo. Os experimentos foram desenvolvidos no município de Selvíria – MS em duas áreas destinadas à pecuária extensiva de corte, subsidiadas pela planta forrageira Urochloa brizantha cv. Marandu. Malhas experimentais de 2,7 e 1,4 hectares, com 70 e 65 pontos, respectivamente, foram instaladas nas áreas e amostras de solo de estrutura deformada e indeformada foram tomadas para avaliação dos atributos físicos e químicos. Também se avaliou os estoques de carbono orgânico total, suas frações granulométricas e a emissão de CO2 nas áreas, visando enxergar os efeitos da reforma sob o aporte de carbono e as emissões de gases de efeito estufa. Em uma das áreas avaliou-se a curva de retenção de água do solo e índice S em todos os... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Soil quality is not something that can be directly measured; however, it can be assessed by the attributes that characterize its physical, chemical and biological state. The choice of more relevant attributes and the interpretation of the measures obtained is not a simple matter, due to the effects of land use change and the interactions between them, the climatic conditions and ecosystem services of each region. The aim of this study was to provide an overview of some indicators of physical and chemical quality of the soil in the context of pasture restoration in the Brazilian Cerrado. The thesis is laid out in chapters, composing in addition to the general considerations presented in Chapter 1, Chapters 2 and 3, which are scientific studies to assess the physical and chemical quality of the soil. The experiments were carried out in the municipality of Selvíria – MS in two areas for extensive beef cattle, subsidized by the forage plant Urochloa brizantha cv. Marandu. Experimental meshes of 2.7 and 1.4 hectares, with 70 and 65 points, respectively, were installed in the areas and soil samples of deformed and undeformed structure were taken to assess the physical and chemical attributes. The total organic carbon stocks, their particle size fractions and the CO2 emission in the areas were also evaluated, aiming to see the effects of the reform under the carbon input and the greenhouse gas emissions. In one of the areas, the soil water retention curve and S index were evaluated ... (Complete abstract click electronic access below) / Doutor
312

Autoregressive Tensor Decomposition for NYC Taxi Data Analysis

Zongwei Li (9192548) 31 July 2020 (has links)
Cities have adopted evolving urban digitization strategies, and most of those increasingly focus on data, especially in the field of public transportation. Transportation data have intuitively spatial and temporal characteristics, for they are often described with when and where the trips occur. Since a trip is often described with many attributes, the transportation data can be presented with a tensor, a container which can house data in $N$-dimensions. Unlike a traditional data frame, which only has column variables, tensor is intuitively more straightforward to explore spatio-temporal data-sets, which makes those attributes more easily interpreted. However, it requires unique techniques to extract useful and relatively correct information in attributes highly correlated with each other. This work presents a mixed model consisting of tensor decomposition combined with seasonal vector autoregression in time to find latent patterns within historical taxi data classified by types of taxis, pick-up and drop-off times of services in NYC, so that it can help predict the place and time where taxis are demanded. We validated the proposed approach using the experiment evaluation with real NYC tax data. The proposed method shows the best prediction among alternative models without geographical inference, and captures the daily patterns of taxi demands for business and entertainment needs.
313

Transfer learning applied to a deep learning system for cardiac abnormality classification in electrocardiograms / Överföringsinlärning tillämpad på ett system för djupinlärning för klassificering av hjärtfel i elektrokardiogram.

Campoy Rodriguez, Adrian January 2022 (has links)
Cardiovascular diseases are a leading cause of death globally. Early diagnosis and treatment is of prime importance to prevent or mitigate health complications. Electrocardiogram (ECG) is a standard test modality used for early diagnosis of arrhythmias. The standard ECG uses 12 leads (i.e., 12 different views of the electrical activity of the heart). However, it is not always possible to perform a standard 12-lead ECG, for instance, in certain emergency situations. Such devices used in emergency situations are able to measure only a subset of leads. Although it is a simpler way of recording ECG, it comes at the cost of losing some information. The project presented in this thesis applies three different models based on canonical correlation analysis (CCA) to perform transfer learning from 12-lead ECGs to improve performance when only a subset of leads is available. The models used were linear canonical correlation analysis, deep canonical correlation analysis (DCCA) and deep canonically correlated bidirectional long short-term memory networks (DCC-BiLSTMs). These models are compared to each other using different configurations to study their performance on ECG data. Linear canonical correlation analysis performed better than its more complex variants, DCCA and DCC-BiLSTMs. With this method, it was possible to improve performance on ECG classification when using two, three, four and six leads in a computationally efficient way. / Hjärt- och kärlsjukdomar är den främsta dödsorsaken i världen. Tidig diagnos och behandling är av största vikt för att förhindra ytterligare och allvarliga hälsoproblem. Elektrokardiogram (EKG) är den standardmetod som används för tidig diagnos av arytmier. Standardförfarandet inom EKG använder sig av 12 avledningar (dvs. 12 olika vyer av hjärtats elektriska aktivitet). Det är dock inte alltid möjligt att utföra ett standard-EKG med 12 ledningar, vilket t.ex. förekommer i vissa nödsituationer. I dessa fall kan utrustning som gör det möjligt att ta fram ett 12-ledars EKG inte vara tillgänglig av flera olika skäl, och därför används andra apparater som kan mäta endast en delmängd av ledningarna för tidig diagnostik. Även om det är ett enklare sätt att utföra ett EKG, innebär det att man förlorar en del information. I det projekt som presenteras i detta dokument används tre olika modeller baserade på kanonisk korrelationsanalys (CCA) för att utföra överföringsinlärning från 12-ledars EKG för att förbättra prestanda när endast en delmängd av avledningar används. De modeller som användes var linjär kanonisk korrelationsanalys, djup kanonisk korrelationsanalys (DCCA) och djupa kanoniskt korrelerade bidirektionella långtidsminnesnätverk (DCCBiLSTMs). Dessa modeller jämförs med varandra med hjälp av olika konfigurationer för att studera deras prestanda på EKG-data. Linjär kanonisk korrelationsanalys presterade bättre än dess mer komplexa varianter, DCCA och DCC-BiLSTMs. Med denna metod var det möjligt att förbättra prestandan för klassificering av EKG när man använder två, tre, fyra och sex ledningar på ett beräkningseffektivt sätt.
314

Kvantová vakua, zakřivený prostoročas a singularity / Quantum vacua, curved spacetime and singularities

Kůs, Pavel January 2021 (has links)
In this work we investigate the Weyl anomaly from a new perspective. Our goal is to identify a set-up for which the classical Weyl symmetry is not broken, at the quantum level by the usual arguments related to the Euler invariants, but rather by the impact of other geometrical obstructions. Therefore, we work, mostly, in three spatiotemporal dimensions, where general arguments guarantee the absence of trace anomalies. In par- ticular, our interest here is on whether various types of singularities, emerging in the description of the differential geometry of surfaces, could induce some form of quantum inequivalence, even though the classical symmetry is at work. To this end, we work with a very special three-dimensional metric, whose nontriviality is fully in its spatial two-dimensional part. The last ingredient we use, to clean-up the way from other com- plications, is to work with physical systems where no Weyl gauge field is necessary, to have the classical invariance. The system we focus on is then the massless Dirac field the- ory (that, as well known, enjoys local Weyl symmetry) in three-dimensional conformally flat spacetimes. With these premises, the research programme consists of three steps. The first step is to find the coordinate transformations that link the conformal factor identifying the...
315

Spatiotemporal Variation of Karst Ecosystem Service Values and Its Correlation With Environmental Factors in Northwest Guangxi, China

Zhang, Mingyang, Zhang, Chunhua, Wang, Kelin, Yue, Yuemin, Qi, Xiangkun, Fan, Feide 01 November 2011 (has links)
In this investigation we analyzed the spatiotemporal variation of ecosystem service values (ESVs) and its correlation with numerous environmental factors (EFs) for the karst region of Northwest Guangxi, China, from 1985 to 2005 using remote sensing, geographic information systems (GIS) and statistical techniques. The results indicate that historically ESVs for this karst region decreased from 1985 (109.652 billion Yuan) to 1990 (88.789 billion Yuan) and then increased at the turn of the twenty-first century. However, the ESVs in both 2000 (103.384 billion Yuan) and 2005 (106.257 billion Yuan) never achieved the level recorded in 1985. The total of nutrient cycling, organic production and gas regulation combined were 72.69, 64.57, 70.18 and 72.10% of ESVs in 1985, 1990, 2000 and 2005, respectively. In contrast, the ESVs of water conservation, soil reservation, recreation and culture were determined to be relatively low contributing only 17.44, 23.82, 19.26 and 24.76% of total ESVs, respectively, during these four years. With regards to the spatial distribution of ESVs, larger values were recorded in the west and smaller ones recorded in the east. The most significant factors that were deemed to influence ESVs are annual rainfall, per capita cropland, slope and vegetation coverage. Annual rainfall and slope exert a negative force, whereas per capita cropland and vegetation coverage exert a positive force on ESVs. The results of the study would suggest that ecosystem conditions of this important karst region have been improved as the result of the implementation of rocky desertification control policies.
316

Das absolutstetige Spektrum eines Matrixoperators und eines diskreten kanonischen Systems / The absolutely continuous spectrum of a matrix operator and a discrete canonical system

Fischer, Andreas 19 April 2004 (has links)
In the first part of this thesis the spectrum of a matrix operator is determined. For this the coefficients of the matrix operator are assumed to satisfy rather general properties which combine smoothness and decay. With this the asymptotics of the eigenfunctions can be determined. This in turn leads to properties of the spectra with the aid of the M-matrix. In the second part it will be shown that if a discrete canonical system has absolutely continuous spectrum of a certain multiplicity, then there is a corresponding number of linearly independent solutions y which are bounded in a weak sense.
317

Analýza slovosledu v korpusu spontánních konverzací matek s dětmi / Word order in spontaneous conversations of mothers with children

Kohoutková, Jolana January 2021 (has links)
The aim of this thesis is to analyse word order in transitive sentences in natural production of two- and four-year old children during Czech language acquisition. The theoretical part focuses on language acquisition in general, in children in a given age period and on the acquisition of transitive sentences in children, discussed in studies carried out abroad. The results of these studies work with a thesis about a canonical word order, which is the first to emerge in child production and reception, while other types of word order might pose a problem for children with regards to interpretation. In order to be able to compare these findings with Czech language, data from an existing corpora of child conversations with their mothers were coded for the purposes of the practical part of this thesis. This data is subsequently analysed in the practical part, with the findings of these analyses implying that in spontaneous language production of Czech children, it is impossible to unambiguously track the preferences for canonical word order, as well as difficulties in adopting word order other than canonical. This thesis also brings basic descriptive information about the word order in transitive sentences both in children over time and in relation to word order that is used by their mothers. Key words...
318

CSP dichotomy for ω-categorical monadically stable structures

Bodor, Bertalan 18 January 2022 (has links)
The constraint satisfaction problem (CSP) over a structure A with a finite relational signature, denoted by CSP(A), is the problem of deciding whether a given finite structure B with the same signature as A has a homomorphism to A. Using concepts and techniques from universal algebra, Bulatov and Zhuk proved independently that if A is finite, then the CSP over A is always in P or NP-complete. Following this result, it is a natural question to ask when and how this dichotomy can be generalized for infinite structures. The infinite-domain CSP dichotomy conjecture (originally formulated by Bodirsky and Pinsker [BPP14]) states that the same complexity dichotomy holds for first-order reducts of finitely bounded homogeneous structures. This conjecture has been solved for many special classes of structures. In this thesis we are developing new techniques involving canonical polymorphisms to attack this conjecture. Using these techniques we prove a new CSP dichotomy result, namely we show that the CSP over every finitely related ω-categorical monadically stable structure is in P or NP-complete.
319

THE ROLE OF CANONICAL TRANSIENT RECEPTOR POTENTIAL CHANNEL SUBTYPE-6 IN PHENOTYPIC MODULATION OF VASCULAR SMOOTH MUSCLE CELLS AND ARTERIAL HEALING AFTER VASCULAR INTERVENTION

Smith, Andrew Hart 26 January 2021 (has links)
No description available.
320

Null Values and Null Vectors of Matrix Pencils and their Applications in Linear System Theory

Dalwadi, Neel 20 December 2017 (has links)
No description available.

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