Population Genetic Approaches to Speciation of Wild Tomatoes with Special Reference to Solanum habrochaites and S. arcanum

This thesis entails the results of three research projects. These have focused on the influence of diversity, demography and structure in the divergence (i.e. the speciation process) of four wild tomato species. In the first project, using coalescent simulations, we studied the impact of three different sampling schemes on patterns of neutral diversity in structured populations. Specifically, we evaluated two summary statistics based on the site frequency spectrum (Tajima’s D and Fu and Li’s D) as a function of migration rate, demographic history of the entire metapopulation and the sampling scheme. Using simulations, we demonstrate strong effects of the sampling scheme on Tajima’s D and Fu and Li’s D statistics, particularly under specieswide expansions. Under such scenarios, the effects of spatial sampling may persist up to very high levels of gene flow (Nm > 25). This suggests that validating the assumption of panmixia is crucial if robust demographic inferences are to be made from local or pooled samples. For the second project, we investigated how selection acts in four species of wild tomatoes (S. habrochaites, S. arcanum, S. peruvianum, and S. chilense) using sequence data from eight housekeeping genes. Our analysis quantified the number of adaptive and deleterious mutations, and the distribution of fitness effects of new mutations (its mean and variance) taking into account the demography of the species. We found no evidence for adaptive mutations but very strong purifying selection in coding regions of the four species. More interestingly, the four species exhibit different strength of purifying selection in non-coding regions (introns). Taking into account the results from the first project, we also highlighted the utility of analyzing pooled samples and local samples from a metapopulation in order to measure selection and the distribution of fitness effects. Finally, the third project deals with the estimation of nucleotide diversity and population structure in S. habrochaites and S. arcanum. We also compared these results to those of S. peruvianum and S. chilense. We found that S. arcanum and S. habrochaites present lower diversity levels than S. peruvianum and S. chilense. Our neutrality tests have not revealed any particular pattern, leading us to conclude that the loci sequenced for the present study have not evolved under strong positive selection, although they show a distinctive pattern of purifying selection (second project). We also tested the demography of all four species and found a strong expansion after a bottleneck in the recent past for S. peruvianum and a similar statistically significant pattern for S. arcanum, even though the signal seemed weaker in this case. Additionally, we found moderate levels of population sub-structure in these species, similar to previous results found in S. peruvianum and S. chilense. Still, regardless of the levels of population structure, we found at least two (Rupe and San Juan from S. arcanum) populations collected in the field that could actually be considered as a single deme. We also expanded these population structure analyses to gain insight into the phylogenetic relations between the four species in order to contribute to the taxonomical treatment of the Solanum section Lycopersicon from a population genetics perspective. Thus, we found a clear differentiation between S. arcanum and S. peruvianum based on all polymorphic sites

El problema de la validez en H. Kelsen

La problemática que gira en torno a la validez ha tenido en velo a muchos autores de la filosofía contemporánea en el ámbito jurídico. Sin embargo, no es hasta la aparición de la Teoría Pura del Derecho de H. Kelsen que se produce un punto de inflexión en esta esfera. La intención principal de este Trabajo es exponer el planteamiento del filósofo sobre esta cuestión, intentando solucionar los problemas tangentes a la misma con el fin de sentar las bases de una ciencia jurídica autónoma limitada estrictamente al Derecho Positivo. Si bien la problemática no consigue esclarecerse de manera contundente, no podemos negar la originalidad e innovación que Kelsen introduce en el ámbito del pensamiento jurídico hasta el punto de convertirse en un referente Imprescindible, incluso en la actualidad.The problem of validity has veiled many authors of contemporary philosophy in the legal ambit. However, it was not until the publication of H. Kelsen's Pure Theory of Law that an inflection point was reached in this sphere. The main intention of this paper is to set out the philosopher's approach to this issue in an attempt to solve the tangential problems in order to establish the bases of an autonomous legal science strictly limited to Positive Law. Although the problem is not resolved in a conclusive way, we cannot deny the originality and innovation that Kelsen introduces in the field of legal philosophy to the point of becoming a reference nowadays.Departamento de Derecho Penal e Historia y Teoría del DerechoGrado en Derech

Failure Analysis of Steam Generator Tubes

Steam generator fabricated of alloy 600 tubes has been replaced in the last decades by newer versions built with alloy 690 or alloy 800 tubes. At first, it was thought that both alloys were resistant to SCC mechanisms but after several years of operation, some NPPs developed denting processes and IGSCC, especially in alloy 800. Corrosion products accumulated in the crevice area between tube-sheet and secondary tube surface of SG increase the stresses and produce a chemical more aggressive to the environment. These two points are the main factor to occur “denting” and increase the possibility of ODSCC can be developed. This chapter describes the failure analysis of an alloy 800 SG tube with only nine years of operation. Microstructural characterization of sludge was carried out after the cleaning by mechanical tube sheet water lancing. SEM/EDX, surface analysis by Auger, and XPS spectroscopy were used to identify chemical species over the OD surface and the fracture surface of some open cracks. "Denting" mechanism is related to flow accelerated corrosion and oxidant particles introduced into secondary side of SG. Therefore, it is convenient to prevent the impurities intake into SG and perform a chemical cleaning process to avoid the hard sludge formation

Photovoltaic energy prediction using machine learning techniques.

Solar energy is becoming one of the most promising power sources in residential, commercial, and industrial applications. Solar photovoltaic (PV) facilities use PV cells that convert solar irradiation into electric power. PV cells can be used in either standalone or grid-connected systems to supply power for home appliances, lighting, and commercial and industrial equipment. Managing uncertainty and fluctuations in energy production is a key challenge in integrating PV systems into power grids and using them as steady, standalone power sources. For this reason, it is very important to forecast solar energy power output. In this paper, we analyze and compare various methods to predict the production of photovoltaic energy for individual installations and network areas around the world, using statistical methods for time series and different machine learning techniques.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

LCG Service Challenge 3 at the Spanish Tier-1 and Tier-2 sites

This note describes the participation of the Spanish centres PIC and CIEMAT in the LCG Service Challenge 3 as Tier-1 and Tier-2 sites respectively. Data transfer, job submission and data throughput from mass storage to the data processing jobs have been successfully exercised at the desired level. Very valuable experience has been gained running the complex computing system under realistic conditions at a signi cant scale

Incubation with a complex orange essential oil leads to evolved mutants with increased resistance and tolerance

Emergence of strains with increased resistance/tolerance to natural antimicrobials was evidenced after cyclic exposure to carvacrol, citral, and (+)-limonene oxide. However, no previous studies have reported the development of resistance and tolerance to complex essential oils (EOs). This study seeks to evaluate the occurrence of Staphylococcus aureus strains resistant and tolerant to a complex orange essential oil (OEO) after prolonged cyclic treatments at low concentrations. Phenotypic characterization of evolved strains revealed an increase of minimum inhibitory and bactericidal concentration for OEO, a better growth fitness in presence of OEO, and an enhanced survival to lethal treatments, compared to wild-type strain. However, no significant differences (p > 0.05) in cross-resistance to antibiotics were observed. Mutations in hepT and accA in evolved strains highlight the important role of oxidative stress in the cell response to OEO, as well as the relevance of the cell membrane in the cell response to these natural antimicrobials. This study demonstrates the emergence of S. aureus strains that are resistant and tolerant to EO (Citrus sinensis). This phenomenon should be taken into account to assure the efficacy of natural antimicrobials in the design of food preservation strategies, in cleaning and disinfection protocols, and in clinical applications against resistant bacteria

Genetic Variants and Phenotypic Characteristics ofSalmonellaTyphimurium-Resistant Mutants after Exposure to Carvacrol

The emergence of antimicrobial resistance has raised questions about the safety of essential oils and their individual constituents as food preservatives and as disinfection agents. Further research is required to understand how and under what conditions stable genotypic resistance might occur in food pathogens. Evolution experiments onSalmonellaTyphimurium cyclically exposed to sublethal and lethal doses of carvacrol permitted the isolation of SeSCar and SeLCar strains, respectively. Both evolved strains showed a significant increase in carvacrol resistance, assessed by minimum inhibitory and bactericidal concentrations, the study of growth kinetics in the presence of carvacrol, and the evaluation of survival under lethal conditions. Moreover, antibiotic susceptibility tests revealed a development of SeLCar resistance to a wide range of antibiotics. Whole genome sequencing allowed the identification of single nucleotide variations in transcriptional regulators of oxidative stress-response:yfhPin SeSCar andsoxRin SeLCar, which could be responsible for the increased resistance by improving the response to carvacrol and preventing its accumulation inside the cell. This study demonstrates the emergence of S. Typhimurium-resistant mutants against carvacrol, which might pose a risk to food safety and should therefore be considered in the design of food preservation strategies, or of cleaning and disinfection treatments

Emerging mutant populations of Listeria monocytogenes EGD-e under selective pressure of Thymbra capitata essential oil question its use in food preservation

Due to their excellent antimicrobial properties, essential oils (EO) have been proposed as potential preservatives for certain kinds of foods, such as dairy products. However, the occurrence of pathogenic populations that are resistant to EOs could pose a health risk. This report seeks to assess the emergence of resistant populations in Listeria monocytogenes EGD-e growth at 37 °C under selective pressure of Thymbra capitata EO (TCO), to characterise their resistance in laboratory media, and to identify their genotypic changes, as well as to evaluate the resistance in skimmed milk. TCO cyclic treatment allowed the isolation of two L. monocytogenes EGD-e resistant strains against the EO: LmSTCO by sublethal doses (75 µL/L TCO) and LmLTCO by lethal doses (300 µL/L TCO) after 20 and 30 cycles, respectively. Both strains displayed an increase of the minimum inhibitory and bactericidal concentration against TCO and a higher survival rate after lethal treatments than the wild-type strain (LmWT). Growth kinetics revealed a better adaptation of LmSTCO in presence of TCO, while LmLTCO grew more slowly compared to LmWT, even in the absence of the antimicrobial. Moreover, a slight increase in cross-resistance to antibiotics was observed: LmSTCO to β-lactams and LmLTCO to a series of broad-spectrum antibiotics. The genomic study revealed one sole nucleotide change in LmSTCO located in plsC gene codifying an enzyme involved in the production of phosphatidic acid, a precursor in cell membrane synthesis. Five genetic variations were found in LmLTCO: among them, the deletion of an ATP-synthesis system involved in slowing bacterial growth. Inhibition and inactivation assays in skimmed milk confirmed the increased resistance of both strains, thereby indicating a safety risk in case these strains emerge in the food chain. These results strongly suggest that the occurrence of such resistances should be taken into account in order to ensure the efficacy of natural antimicrobials in the design of food preservation strategies