During meiosis, homologous chromosomes pair and undergo reciprocal genetic exchange, producing crossovers. This generates genetic diversity and is required for balanced homolog segregation. Despite the critical functions of crossovers, their frequency and distribution varies extensively within and between species. This crossover variation can be caused by trans-modifiers within populations, which encode diffusible molecules that influence crossover formation elsewhere in the genome. This project utilised natural accessions of Arabidopsis thaliana to identify trans-modifying loci underlying crossover variation within the species. I performed Quantitative Trait Loci (QTL) mapping using a fluorescence-based crossover reporter system to measure recombination frequency in a genomic interval on chromosome 3, termed 420. Mapping in a Col-420 × Bur-0 F2 population revealed four major recombination QTLs (rQTLs) that influence crossover frequency. A novel recessive rQTL on chromosome 1 that reduced crossovers within the interval was fine-mapped to a premature stop codon in TATA Binding Protein (TBP)-associated factor 4b (TAF4b) in Bur-0 (taf4b-1). TAF4b is a subunit of the TFIID complex, a multi-protein general transcription factor complex comprising TBP and numerous TAFs that forms a component of the pre-initiation complex that recruits RNA polymerase II to promoters. Transformation-based complementation experiments and the isolation of several independent taf4b alleles provided genetic proof that TAF4b is essential for wild-type levels of crossover within 420. Analysis of the prevalence of the taf4b-1 mutation in the global Arabidopsis accession collection demonstrated its specificity to three accessions in the British Isles. A combination of cytology, genetic analysis using additional fluorescent reporter lines, and sequencing in F2 recombinant populations demonstrated a genome-wide reduction in crossover frequency in taf4b-1. In addition, RNA sequencing identified numerous transcriptional changes in taf4b-1. Both up- and down-regulated gene sets displayed significant enrichment for genes that are predominantly expressed in meiocytes, and several gene ontology terms pertaining to protein modification and meiotic processes. These results further demonstrate the existence of genetic modifiers of crossover frequency in natural populations of A. thaliana, and the characterisation of a novel trans-modifier of recombination, TAF4b. This signifies a novel function for TAF4b in Arabidopsis, and further enhances our understanding of the molecular factors controlling the frequency and distribution of meiotic crossovers in plants.

El progrés i les millores assolides en el camp industrial han empès els investigadors a buscar eines més refinades per tal de modelar aquests processos amb un major grau de precisió. Les propietats termofísiques són necessàries i el seu coneixement ha de ser molt precís, ja que una predicció poc acurada pot afectar el disseny d'una operació unitària, amb una consegüent pèrdua de rendiment i diners. Actualment, els models teòrics han progressat com a eines modernes que poden proveir a l'usuari d'una quantitat ingent d'informació sobre un fluid de manera ràpida, neta i barata. En qualsevol cas, manca encara un llarg camí per trobar una eina poderosa capaç de calcular el comportament termodinàmic de qualsevol compost en qualsevol condició. Aquest treball utilitza una robusta equació d'estat anomenada soft-SAFT. El nom original prové de la Teoria Estadística de Fluids Associants (SAFT), que és una equació basada en principis de mecànica estadística. Posseeix una molt forta base molecular, proposant un model "físic" per a descriure el compost. Soft-SAFT és una variant de la SAFT original que utilitza un terme de referència basat en una interacció de tipus Lennard-Jones entre les molècules. Malgrat que l'equació prèvia ja havia estat provada de manera exitosa en un conjunt molt variat de treballs, encara fallava en una regió molt important del diagrama de fases: la regió crítica. En aquesta regió, les propietats sofreixen fortes fluctuacions i canvien dràsticament degut a les llargues correlacions que es produeixen entre les molècules. La versió original de la soft-SAFT no pot tenir en compte aquestes fluctuacions de llarg abast perquè està basada en una teoria de camp mig. Tanmateix, aquesta fallida de la teoria ha estat superada introduint un tractament específic de "crossover", que considera les fluctuacions inherents. El procediment està basat en la teoria del grup de renormalització de Wilson (1971) i va ser desenvolupada per White (1992). S'escriu com un joc de relacions recursives on les correlacions entre les molècules són considerades al llarg de vàries iteracions. L'objectiu d'aquest treball de tesi s'ha dedicat a la millora d'una equació d'estat amb base molecular anomenada soft-SAFT afegint el tractament específic de "crossover" mencionat abans. La meta general implica el desenvolupament d'una poderosa eina predictiva aplicable a tot tipus de condicions per càlculs termodinàmics. Un tractament específic per calcular les fluctuacions inherents presents a la regió crítica s'ha implementat dins de la equació. La nova equació, anomenada "crossover soft-SAFT" és utilitzada per estudiar tres famílies diferents d'hidrocarburs: els alcans, els alcanols i els perfluoroalcans, així com les seves mescles entre ells i amb altres compostos, com el diòxid de carboni o l'àcid clorhídric. Els paràmetres moleculars s'optimitzen emprant dades de densitat de líquid i pressió de vapor experimental pels primers vuit membres de cada família. Es proposa una correlació per a cada paràmetre respecte el pes molecular, i els paràmetres s'extrapolen per predir el comportament termodinàmic d'altres membres més pesats de la mateixa família, amb un grau de precisió similar a l'obtingut pels membres més lleugers. Les capacitats calorífiques, la compressibilitat isotèrmica o isentròpica i la velocitat del so han estat també calculats per totes aquestes famílies de compostos, obtenint novament un molt bon acord amb les dades experimentals en la majoria de casos. Els resultats obtinguts per a aquestes propietats resulta molt esperançador ja que aquests càlculs s'han realitzat d'una manera purament predictiva. S'han pogut reproduir les diferents singularitats observades experimentalment en la regió veïna al punt crític, mentre que el càlcul dels exponents crítics universals també ha revelat un acord amb les mesures experimentals. Aquest treball pretén ser un pas endavant en la millora de les eines de modelat molecular per aplicacions enginyerils. Malgrat que la natura sigui sempre sorprenent i difícil de reproduir, l'esforç dedicat a aquesta tasca és prou encoratjador per continuar buscant noves fórmules que ens donin la possibilitat d'acostar-nos una mica més al món real. / The progress and the improvements made in the industrial field have pushed the researchers to look for refined tools to model these processes with a higher degree of accuracy. Thermophysical properties are needed and have to be known in a precise way, because an inaccurate prediction may affect the design of a unit property, with a result of a loss in yield and money. Nowadays, the theoretical models have progressed as modern tools that can provide a huge amount of information of a fluid in a rapid, clean and cheap manner. In any case, there is still a long way to find a powerful tool able to calculate the thermodynamic behavior of any compound at any condition. This work uses a robust equation of state called soft-SAFT. The original name comes from the Statistical Associating Fluid Theory (SAFT), which is an equation based on statistical mechanics principles. It has a very strong molecular basis, proposing a "physical" model to describe the compound. Soft-SAFT is a variant of the original SAFT that uses a reference term based on a Lennard-Jones type interaction among the molecules. Although the previous equation had already been successfully tested in many different works, it still failed in a very important region of the phase diagram: the critical region. In that region, the properties suffer strong fluctuations and change drastically due to the long-correlations established among the molecules. The original soft-SAFT version of the equation can not take into account these long-range fluctuations because it is based in a mean-field theory. However, this lack of the theory can be now overcome introducing a specific crossover treatment that considers these inherent fluctuations. The procedure is based in the renormalization group treatment of Wilson (1971) and it was developed by White (1992). It is written as a set of recursive relations where the correlations among the molecules are considered in several iterations. The objective of this thesis work was to improve the molecular-based equation of state named soft-SAFT adding the specific crossover treatment before mentioned. The general aim was to develop a powerful predictive tool applicable under different conditions for thermodynamic calculations. The extended equation, called crossover soft-SAFT is employed to study three different families of hydrocarbons: the n-alkanes, the 1-alkanols and the n-perfluoroalkanes, and their mixtures among them and with other compounds such as carbon dioxide or hydrogen chloride. The molecular parameters are optimized using liquid density and vapor pressure data for the first eight members of each family. A correlation with molecular weight is then proposed, and the parameters are extrapolated to predict the phase behavior of heavier members of the same family, with the same degree of accuracy as that one obtained for the lighter members of the series. Heat capacities, isothermal and isentropic compressibility and the speed of sound have been calculated for these families obtaining very good agreement with experimental data in most of the cases. Results for these properties are very encouraging since calculations were performed in a pure predictive manner. The different singularities experimentally observed in the vicinity of the critical point have been reproduced and the universal critical exponents have also been found in agreement with the experimental measurements. This work intends to be a step forward in the improvement of the molecular modeling tools for engineering applications. Although nature is always surprising and difficult to reproduce, the effort devoted to this task is encouraging enough to continue looking for new formulas that give us the possibility of getting closer to the real world.

To ran a DMFC without methanol crossover is the aim of this study.It is done by supplying fuel no more than what the anode can consume. The first is to explore the factors that may affect the time constant of vapor feed DMFC. In order to reduce the time constant of current decline, first, we decrease store tank¡¦s space of methanol with different structure of unipolar plate. Second, we reduce the thickness of anode stack and the space above the air bleed valve. Using slide plate instead of air bleed valve can shorten the diffuse distance effectively and reduce the time constant of current rise curve. The second is to explore the impact of supply of methanol on steady-state current of system. Using air bleed valve, because of its high gas tightness, the utilization rate of methanol can exceed 94% without crossover. It was found that in the slide plant experiment, steady-state current value depends mainly on the pore size of slide plate, and resistance value has nothing to do. However, the resistance value is lower, the time required to reach steady-state current is shorter. The third is to explore if the performance decay after long time test of steady-state current. It was found that the performance of MEA will decay while the water content of membrane decreased.

In this experiment, we are going to discuss the possibility of zero methanol crossover to the cathode target within the capacity of DMFC electrode and with proper methanol supply. After various trials, it is found that electrospray can be used to reduce fuel demand. The methanol will be consumed immediately within the electrode capacity. The methanol solution is volatile. As a result, the actual amount of electricity generated will never accord with the input. If we supply the electrode with methanol by direct contact using infusion pump, the volatility will be reduced. The total power generated then accords with the amount of methanol input. Although only low methanol concentration is supported currently, it¡¦s hoped that the crossover problem can be solved completely. In the electrode design, we try to take away the carbon cloth from the anode and leave the catalyst layer. By this way, the methanol is in touch with the catalyst. Such change is good for this experiment. In our study, following difficulties are found: (1) Methanol input (2) The impact of volatility in electrospray (3) When supplying fuels to the surface of electrode, the reaction size is too small. More attentions should be paid in the future cell design.

No description available.

This piece is an exploration of tango music. Having played, arranged, composed, and performed this music since 2011, I consider myself steeped and well-versed in the culture and musical language of tango, and this piece is an attempt to synthesize this rich body of music with my own personal style. This work is firmly grounded in the aesthetic of tango dance music from the “Golden Age” of tango in Argentina (1935-1955) and post-Golden Age music. The intent is to create music that is immediately accessible to a layperson, recognizable as tango to someone conversant in the genre, yet distinctively new and part of the evolution of this music. The instrumentation is a cross between a chamber orchestra and a tango ensemble. Strings, flutes, clarinets, F horns, and percussion are joined by a rhythm section of piano, classical guitar, and two bandoneons (tango concertina). The lone upright bass is considered part of the rhythm section as well, rather than as part of the strings. It comprises five movements and runs approximately 25 minutes.

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Oliveira.pdf: 1720273 bytes, checksum: 1f9a6a7fc8c3efbf6a0e588b4881622e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-03-07T14:20:01Z (GMT). No. of bitstreams: 2 Dissertação_Marcos K. L. Oliveira.pdf: 1720273 bytes, checksum: 1f9a6a7fc8c3efbf6a0e588b4881622e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-02-05 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this work we discuss the behavior of a superconducting system described by a multiband model, so it is an extension of the BCS theory which describes well the low temperature superconductors. We consider the interbanding interaction, that is, the interaction between fermions that present different properties under the influence of hybridization, evaluating the crossover between the weak coupling (BCS) and the strong coupling (BEC) for symmetry type s Order parameter in T = 0 and in the presence of a hybridization. However, the objective of this work is to study superconductivity without a two-band model, with interband interactions, with the purpose of obtaining as equations for the superconducting Gaps and, concomitantly, to evaluate a development of the systems between the limit of weak couplings (BCS) and strong couplings (BEC) and estimate an influence that is a hybridization on the system. Using Zubarev's Green function method, we calculate interband superconducting order parameters and chemical potential as a function of the interaction 1/kpa, in order to obtain a complete study of the system. We explore the energies of excitation at the two limits of the coupling, considering their characteristics and we see that there is a discontinuity in the amplitude of the interband gap. Our results suggest that hybridization V acts at the expense of superconductivity, suppressing it, agreeing with other works, although this is not general, since some works show that V contributes to superconductivity up to a certain value and to other values, destroys it. We also notice that in interband interaction we have first and second order transitions and a tricritic point, in which We have the encounter of a first order line with a second order line. / Neste trabalho é tratado o comportamento de um sistema supercondutor descrito por um modelo multibandas, sendo isto uma extensão da teoria BCS a qual descreve bem os supercondutores de baixas temperaturas. Uma vez que a mesma se limita ao caso de uma única banda. Será Considerado a interação interbanda, isto é, a interação que se dá entre férmions que apresentam propriedades diferentes, sob a influência da hibridização, avaliando o crossover entre os limites de acoplamento fraco (BCS) até o acoplamento forte (BEC) para simetria tipo s do parâmetro de ordem em T = O. Portanto, o objetivo deste trabalho é estudar a supercondutividade no modelo de duas bandas, com interações interbandas, com o propósito de obter as equações para as amplitudes do gap supercondutor e, concomitantemente, avaliar a evolução dos sistemas entre o limite de acoplamentos fracos (BCS) e acoplamentos fortes (BEC) e estimar a influência que a hibridização tem sobre o sistema. Fazendo uso do método das funções de Green de Zubarev, calculamos os parâmetros de ordem supercondutor interbandas e o potencial químico como função da interação, a qual será descrita em termos do comprimento de espalhamento e do número de onda de Fermi, afim de obtermos um estudo completo do sistema. Exploramos as energias de excitação nos dois limites do acoplamento, considerando suas características e vimos que existe uma descontinuidade na amplitude do gap inter-banda. Nossos resultados sugerem que a hibridização V, atua em detrimento da supercondutividade, suprimindo-a, concor-dando com outros trabalhos, apesar de não ser isso geral, uma vez que alguns trabalhos mostram que V contribui para a supercondutividade até um determinado valor e para outros valores, a destrói. Percebemos também que na interação interbanda temos transições de primeira e segunda ordem e um ponto tricrítico, no qual temos o encontro de uma linha de primeira ordem com uma de segunda ordem. Este trabalho se baseia na tese do Professor Dr. Francisco Dinola.

In general, Dual-Band technology enables microwave components to work at two different frequencies. This thesis introduces novel dual-band microwave components and their applications. Chapter 2 presents a novel compact dual-band balun (converting unbalanced signals to balanced ones). The ratio between two working frequencies is analyzed. A novel compact microstrip crossover (letting two lines to cross each other with very high isolation) and its dual-band application is the subject of chapter 3. A dual-frequency cloak based on lumped LC-circuits is introduced in chapter 4. In chapter 5, a dual-band RF device to detect dielectric constant changes of liquids in polydimethylsiloxane (PDMS) microfluidic channels has been presented. Such a device is very sensitive, and it has significantly improved the stability. Finally, conclusion of this thesis and future works are given in chapter 6.

No description available.

Semestral thesis is devoted to mapping and verification technologies for the project active loudspeaker crossover using DSP. Three way systém will use open baffle. Design of analog crossover is complex due to the need of compensating for acoustic short circuit and properties of laudspeakers.