LHCb is a high-precision experiment dedicated to measuring the decays of B hadrons. Particle identification at LHCb relies upon two Ring Imaging Cherenkov (RICH) detectors, and this thesis describes work carried out relating to these detectors. It includes an analysis performed to investigate ion feedback in the Hybrid Photon Detectors (HPDs) used as photosensors for the RICH system, and studies of the performance of a RICH prototype in test beam conditions. A time alignment system for the RICH detectors has been designed and implemented, and this work is presented here. Excellent particle identification performance is required for efficient reconstruction of the b → s penguin decay B0s → ØØ a channel in which visible New Physics effects are possible. An analysis of this decay has been performed, encompassing event selection at trigger and offline levels, resolution, tagging and acceptance studies, and toy monte carlo experiments on sensitivity and systematic errors in measuring the total weak phase. The results are discussed within.

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The supply of drinking water in Gokwe District (NW Zimbabwe) is almost entirely based on groundwater drawn from boreholes and open dug wells. In certain areas of the district, the occurrence of dental fluorosis has been linked to excessive fluoride in the water supplies. A high prevalence of dental fluorosis (about 62%) was previously recorded among school children in the district. The aim of this study was to determine relationships between the spatial distribution of fluoride content in drinking water supplies in Gokwe, and lateral and vertical geological variation. A total of 224 water samples were collected from 196 water sources in the study area (a further 18 water sources just outside the study area were also sampled). All the samples were analysed for fluoride in the field using the fluoride ion selective electrode method (FISE). One hundred and fifty nine duplicate samples were analysed for fluoride and common anions and cations using High Performance Ion Chromatography (HPIC) in the laboratory. Two main groups of computer programmes were employed: (1) Geographic Information System (ArcView® GIS) was used to store, analyse and display multiple layers of surface geologic and geographic information, and (2) a three-dimensional visualisation programme (Rockworks) was used to interpret and illustrate site stratigraphy based on borehole information. Results indicated that the fluoride content of drinking water in the study area ranges from 0 to 9.65 mg/L. Forty-seven water sources (24%) yielded water containing fluoride in excess of the World Health Organisation's (WHO) health limit of 1.5 mg/L F. Of the 47 high fluoride water sources, 43 were boreholes (pumped or artesian). The shallower water sources (dug wells, streams and dams) largely yielded low-fluoride water. / The groundwater fluoride contamination is stratigraphically controlled and originates from carbonaceous material (carbonaceous shales, carbonaceous mudstones and coaly material) within the Lower Madumabisa and Middle Wankie Members of the Lower Karoo Group. It has been shown that in general the greater the proportion of carbonaceous material intersected by a borehole, the greater the fluoride concentration of the water. Probable mineral sources of fluoride within the carbonaceous material include fluorapatite, kaolinite and trona. Chemical parameters that appear to influence the concentration of dissolved F in the water supplies include total dissolved solids (TDS), NaCl and pH. In relatively low fluoride waters, F concentrations generally increase with TDS and NaCl concentrations, whereas the highest F concentrations are found in moderately alkaline (pH 7.8-9) waters. Based on ranges of fluoride concentration in drinking water, fluorosis-risk zones were identified and have been illustrated on a fluorosis-risk map. The zones are: No Risk Zone (0-1.5 mg/L F), Moderate Risk Zone (1.5-3.0 mg/L F), High Risk Zone (3.0-6.0 mg/L F) and the Very High Risk Zone (6.0-10.0 mg/L F). The map suggests that groundwater available to people occupying 3650 km z (60.8%) of the study area potentially contains excessive fluoride (F>1.5 mg/L), presaging the occurrence of dental fluorosis, skeletal fluorosis and crippling skeletal fluorosis in the area. Different strategies may be employed to ameliorate the fluoride problem in Gokwe. / These include sinking new boreholes to optimal depths and in appropriate locations, promoting the use of surface water and shallow groundwater, resettlement and defluoridation. However in order to fully understand the problem and to prescribe these or other solutions more comprehensively, multi-disciplinary studies may be required. Such studies may consider isotopic dating of water to investigate any relationships between fluoride concentration and residence time of water, geochemical analyses of rocks and soils, detailed fluorosis epidemiology studies and test-scale defluoridation investigations.

La désintégration des mésons charmés est étudiée dans le cadre de l'expérience WA82 à partir des données enregistrées au Super Proton Synchrotron (SPS) du CERN. Un total d'environ 4000 candidats a été extrait des 50 millions d'interactions enregistrées de 1987 à 1989. Une part importante de mon travail a consisté à assurer le fonctionnement du détecteur RICH destiné à l'identification des particules secondaires et à analyser les données recueillies. Cette information a pu être utilisée avec succès pour mettre en évidence un signal exploitable pour divers modes de désintégration rares de particules charmées ainsi que pour réduire le bruit de fond dans les modes plus abondants. Les résultats d'une analyse personnelle sont présentés, débouchant sur la mesure de rapports de branchement non-leptoniques des mésons D°, D+- et Ds+-, relativement aux modes les plus fréquents.

The ruthenium dinuclear complexes with end-caping of pyridinedicarboxylate complexes of terpyridine (2,2':6',2'-terpyridine) and (tBu)3-terpyridine (4,4¡¦,4¡¦¡¦-tri-tert-butyl-2,2¡¦:6¡¦,2¡¦¡¦-terpyridine) bridging with carbon-rich alkynyl group are reported. These novel complexes are characterized by NMR, MALDI-MS, FT-IR, UV, and electrochemistry. In comparison with the system of tpy-Ru-tpy-(¡Ý)n-tpy-Ru-tpy, we found some interesting characteristics in the studies of electronic spectra and electrochemical measurements. Furthermore, one reversible and one irreversible electrochemical redox waves in positive wave were observed (E1/2 at 0.59 and 1.15 V (irrev.) for the complex with ethynyl spacer and E1/2 at 0.62 and 1.10 V (irrev.) for the complex with butynyl spacer), indicating a strong electronic interaction between two Ru metal centers. However, in the tpy-Ru-tpy-(¡Ý)n-tpy-Ru-tpy system, only one electrochemical redox wave at ~1.3 V was found. From the electronic and electrochemical analysis , the electronic interaction between two metal centers decreases as the number of alkynyl group increases.

The purpose of my thesis is to explore lesbianism in Adrienne Rich¡¦s essays and poetry. Rich has earned her reputation as a major American poet and essayist since the 1950s. Most attention has been paid to her extraordinary poems and revolutionary prose. However, the issue of lesbianism has seldom been focused on or fully discussed. Therefore, I would try to present a panoramic view on how lesbianism has been developed in Rich¡¦s works. In the first chapter, I have tried to delineate various definitions of ¡§lesbian¡¨, and formulate my own definition. Besides that, I have also introduced some theoretical perspectives of lesbianism. In the second chapter, the discussion is mainly on Rich¡¦s concepts¡X ¡§institutionalization of heterosexuality¡¨, ¡§lesbian existence¡¨ and ¡§lesbian continuum¡¨¡Xwhich were brought up in the essay ¡§Compulsory Heterosexuality and Lesbian Existence.¡¨ In the third chapter, my aim is to delineate the development of Rich¡¦s lesbian perspective in her poetry. The discussion consists of three parts: the first part covers the revelation of women¡¦s oppression; the second is stressed on the concept of androgyny; the last part will present Rich¡¦s idea that women¡¦s power should be based on close relations among women.

The thesis mainly probes into the effects that the structure below multi quantum layer as regards the efficiency of luminescence of blue light LED in the different number layers and make further comparison. In the article, the students separately make analysis and comparison to the single quantum well , five multi quantum wells , ten multi quantum wells and thirty multi quantum wells. And discovered that different number layers of quantum well will occur different Phase Separation and Strain in the film. So the article mainly focuses on : (1.)Phase Separation in various of quantum well, it occurs different In-rich reaction and (2.)Different Strain levels which occurs different dislocation reaction. The two mechanisms will be discussed in detail with the effects of luminescence reaction of LED. According to the results of experiment, We found that it is easier to form V-shape defects and dislocation with the increasing indium content. Under the high indium content, the density of In-rich will increase obviously and spread to the GaN barrier, then the original structure of quantum well will be destroyed and descend the efficacy of luminescence. In the thicker GaInN quantum well, it will induce larger energy of strain inside the film, So the defect density will increase due to release the strain energy. It was also discovered the intensity of luminescence descend after measuring by PL. When grow different number layers , it was discovered that higher quantum layer will produce the roughness surfaces when using AFM . So the higher quantum layers will make greater influence in the efficacy of luminescence. By experiment, we found that the five to ten quantim wells will have the better photo characteristic.

Cancer immunotherapy aims to use and manipulate the host’s immune system to fight against cancer. The objective of this strategy is to induce specific and persistent immune responses leading to tumor eradication. Heat shock proteins (HSP) purified from cancer tissues have been identified as unique mediators of specific anti-tumor immunity. In our laboratory, we have developed an original vaccine, termed CRCL (Chaperone-Rich Cell Lysate) that consists of multiple HSP complexes enriched from tumor lysates. CRCL immunization leads to an efficient protection against a wide variety of murine cancers by inducing a strong, long-lasting, and specific T and NK-cell dependent immune responses against the tumor from which it has been generated. Tumor-derived CRCL has been shown to be more efficient in triggering DC activation than individual purified HSP or tumor lysates. The immunostimulatory effects of CRCL arise from its superior ability to provide a wide variety of tumor antigens to the immune system and by providing potent adjuvant effects. However, CD4⁺CD25⁺ regulatory T lymphocytes (Treg) critically contribute to the mechanisms of cancer-induced suppression. Data from independent groups including ours suggests they may also restrain the function of antigen presenting cells. The current study was designed to elucidate the molecular signaling events triggered by the tumor-derived CRCL vaccine in antigen presenting cells and evaluate whether CRCL may overcome the inhibitory effects of Treg modulation of DC and macrophage activation. Our results indicate CRCL activates DC and macrophages by inducing proinflammatory cytokine chemokine secretion. CRCL induces iNOS expression and NO production in macrophages. CRCL activation of DC and macrophages results in transcription factor NF-κB activation in vitro and in vivo, and this includes the activation of additional signaling molecules upstream of NF-κB. Following CRCL treatment the phenotypic maturation of DC, the production of DC and macrophage pro-inflammatory cytokines, and the activation of the transcription factor NF-κB are not affected by Treg. Additionally, CRCL induced activation of DC is not diminished by the immunosuppressive cytokine TGF-β 1. Our results indicate tumor-derived CRCL-treated DC and macrophages are refractory to Treg inhibition. These results are important for advancing CRCL-based vaccines in Phase I clinical trials.

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