Supersymmetric Dark Matter : aspects of sfermion coannihilations

There is very strong evidence that ordinary matter in the Universe is outweighed by almost ten times as much so-called dark matter. Dark matter does neither emit nor absorb light and we do not know what it is. One of the theoretically favoured candidates is a so-called neutralino from the supersymmetric extension of the Standard Model of particle physics. A theoretical calculation of the expected cosmic neutralino density must include the so-called coannihilations. Coannihilations are particle processes in the early Universe with any two supersymmetric particles in the initial state and any two Standard Model particles in the final state. In this thesis we discuss the importance of these processes for the calculation of the relic density. We will go through some details in the calculation of coannihilations with one or two so-called sfermions in the initial state. This includes a discussion of Feynman diagrams with clashing arrows, a calculation of colour factors and a discussion of ghosts in non-Abelian field theory. Supersymmetric models contain a large number of free parameters on which the masses and couplings depend. The requirement, that the predicted density of cosmic neutralinos must agree with the density observed for the unknown dark matter, will constrain the parameters. Other constraints come from experiments which are not related to cosmology. For instance, the supersymmetric loop contribution to the rare b -> sγ decay should agree with the measured branching fraction. The principles of the calculation of the rare decay are discussed in this thesis. Also on-going and planned searches for cosmic neutralinos can constrain the parameters. In one of the accompanying papers in the thesis we compare the detection prospects for several current and future searches for neutralino dark matter.

Shedding light on the role of the prokaryotic assemblage in the biogeochemical cycles of the dark ocean

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The evolution of health status and chronic conditions in Catalonia, 1994-2006: the paradox of health revisited using the Blinder - Oaxaca decomposition

[EN] Background: The paradox of health refers to the improvement in objective measures of health and the increase in the reported prevalence of chronic conditions. The objective of this paper is to test the paradox of health in Catalonia from 1994 to 2006. Methods: Longitudinal cross-sectional study using the Catalonia Health Interview Survey of 1994 and 2006. The approach used was the three-fold Blinder - Oaxaca decomposition, separating the part of the differential in mean visual analogue scale value (VAS) due to group differences in the predictors (prevalence effect), due to differences in the coefficients (severity effect), and an interaction term. Variables included were the VAS value, education level, labour status, marital status, all common chronic conditions over the two cross-sections, and a variable for non-common chronic conditions and other conditions. Sample weights have been applied. Results: Results show that there is an increase in mean VAS for men aged 15-44, and a decrease in mean VAS for women aged 65-74 and 75 and more. The increase in mean VAS for men aged 15-44 could be explained by a decrease in the severity effect, which offsets the increase in the prevalence effect. The decrease in mean VAS for women aged 65-74 and 75 and more could be explained by an increase in the prevalence effect, which does not offset the decrease in the severity effect. Conclusions: The results of the present analysis corroborate the paradox of health hypothesis for the population of Catalonia, and highlight the need to be careful when measuring population health over time, as well as their usefulness to detect population's perceptions.

Respiration in the dark ocean

[EN]The dark ocean, the waters below 200 m depth, comprises about 95% of the volume of the ocean, but its contribution to the metabolism of the ocean is poorly quantified. Here we show that the respiration rate of microplankton declines exponentially at a rate of 0.53 km−1 in the dark ocean, and is enhanced at the interface between the mesopelagic and the abyssal layers (1,000–2,000 m). The respiratory CO2 production in the dark ocean, estimated at 20 to 33.3 Gt C yr−1, renders it a major component of the carbon flux in the biosphere.

Significance of non‐sinking particulate organic carbon and dark CO2 fixation to heterotrophic carbon demand in the mesopelagic northeast Atlantic

[EN] It is generally assumed that sinking particulate organic carbon (POC) constitutes the main source of organic carbon supply to the deep ocean's food webs. However, a major discrepancy between the rates of sinking POC supply (collected with sediment traps) and the prokaryotic organic carbon demand (the total amount of carbon required to sustain the heterotrophic metabolism of the prokaryotes; i.e., production plus respiration, PCD) of deep-water communities has been consistently reported for the dark realm of the global ocean. While the amount of sinking POC flux declines exponentially with depth, the concentration of suspended, buoyant non-sinking POC (nsPOC; obtained with oceanographic bottles) exhibits only small variations with depth in the (sub)tropical Northeast Atlantic. Based on available data for the North Atlantic we show here that the sinking POC flux would contribute only 4–12% of the PCD in the mesopelagic realm (depending on the primary production rate in surface waters). The amount of nsPOC potentially available to heterotrophic prokaryotes in the mesopelagic realm can be partly replenished by dark dissolved inorganic carbon fixation contributing between 12% to 72% to the PCD daily. Taken together, there is evidence that the mesopelagic microheterotrophic biota is more dependent on the nsPOC pool than on the sinking POC supply. Hence, the enigmatic major mismatch between the organic carbon demand of the deep-water heterotrophic microbiota and the POC supply rates might be substantially smaller by including the potentially available nsPOC and its autochthonous production in oceanic carbon cycling models.

Tourism: low-cost airlines, climate and economic crisis

Programa de doctorado: Economía

Properties of gas and dark matter in X-ray galaxy clusters with Sunyaev Zel'dovich measurements

I have studied entropy profiles obtained in a sample of 24 X-ray objects at high redshift retrieved from the Chandra archive. I have discussed the scaling properties of the entropy S, the correlation between metallicity Z and S, the profiles of the temperature of the gas, Tgas, and performed a comparison between the dark matter 'temperature' and Tgas in order to constrain the non-gravitational processes which affect the thermal history of the gas. Furthermore I have studied the scaling relations between the X-ray quantities and Sunyaev Zel'dovich measurements. I have observed that X-ray laws are steeper than the relations predicted from the adiabatic model. These deviations from expectations based on self-similarity are usually interpreted in terms of feedback processes leading to non-gravitational gas heating, and suggesting a scenario in which the ICM at higher redshift has lower both X-ray luminosity and pressure in the central regions than the expectations from self-similar model. I have also investigated a Bayesian X-ray and Sunyaev Zel'dovich analysis, which allows to study the external regions of the clusters well beyond the volumes resolved with X-ray observations (1/3-1/2 of the virial radius), to measure the deprojected physical cluster properties, like temperature, density, entropy, gas mass and total mass up to the virial radius.

Dark humour as a culture specific phenomenon: a study in screen translation

The present study aims at analyzing how dark humour as a cinematic genre travels cross-culturally through a specific mode of audiovisual translation, i.e. dubbing. In particular, it takes into consideration the processes involved in dubbing humour from English into Italian as observed in the English- and Italian-language versions of ten British and American dark comedies from the 1940s to the 2000s. In an attempt to identify some of the main mechanisms of the dark humour genre, the humorous content of the films was analyzed in terms of the elements on which specific scenes are based, mainly the non-verbal and verbal components. In the cases in which verbal elements were involved, i.e. the examples of verbally expressed humour, the analysis was concerned with whether they were adapted into Italian and to what effect. Quantification of the different kinds of dark humour revealed that in the sample of dark comedies verbal dark humour had a higher frequency (85.3%) than non-verbal dark humour (14.7%), which partially disconfirmed the first part of the research hypothesis. However, the significance of contextual elements in the conveying of dark humour, both in the form of Nsp VEH (54.31%) and V-V (V+VE) (21.68%), provided support for the hypothesis that, even when expressed verbally, dark humour is more closely linked to context-based rather than purely linguistic humour (4.9%). The second part of the analysis was concerned with an investigation of the strategies adopted for the translation of verbal dark humour elements from the SL (English) into the TL (Italian) through the filter of dubbing. Four translational strategies were identified as far as the rendering of verbal dark humour is concerned: i) complete omission; ii) weakening; iii) close rendering; and iv) increased effect. Complete omission was found to be the most common among these strategies, with 80.9% of dark humour examples being transposed in a way that kept the ST’s function substantially intact. Weakening of darkly humorous lines was applied in 12% of cases, whereas increased effect accounted for 4.6% and complete omission for 2.5%. The fact that for most examples of Nsp VEH (84.9%) and V-AC (V+VE) (91.4%) a close rendering effect was observed and that 12 out of 21 examples of V-AC (PL) (a combined 57%) were either omitted or weakened seemed to confirm, on the one hand, the complexity of the translation process required by cases of V-AC (PL) and V-AC (CS). On the other hand, as suggested in the second part of the research hypothesis, the data might be interpreted as indicating that lesser effort on the translator/adaptor’s part is involved in the adaptation of V-AC (Nsp VEH) and V-V (V+VE). The issue of the possible censorial intervention undergone by examples of verbal dark humour in the sample still remains unclear.