Looking for light Dark Matter with CCDs in the DAMIC experiment

De nombreuses observations astrophysiques et cosmologiques tendent à favoriser le fait que 80% de la matière de l’Univers est constitué d’une matière inconnue et interagissant peu avec la matière ordinaire, la matière sombre. Cependant sa nature reste une des inconnues de la physique moderne. Actuellement la vaste majorité des expériences de détection directe de matière sombre n’ont encore rien détecté. L’expérience Dark Matter In CCDs (DAMIC) à SNOLAB est l’une d’entre elles et utilise des Charged Coupled Devices (CCDs, semi-conducteurs en silicium, comme détecteur. Mon travail au sein de la collaboration DAMIC a été centré sur la production d’un modèle de bruit de fond radioactif à l’aide de l’outil GEANT4. On commencera par introduire l’expérience DAMIC à SNOLAB pour présenter la simulation de l’expérience, de la génération des isotopes radioactifs à la simulation de la réponse du détecteur aux dépôts d’énergies des particules simulées. J’exposerai ensuite les origines et caractéristiques des différents isotopes présents dans l’expérience, informations que l’on a obtenues grâce à des mesures dites de screening, des publications et analyses. Pour terminer je présenterais le modèle de bruit de fond radioactif issu de l’ajustement des simulations au données et la sensibilité de l’expérience DAMIC.A large number of astrophysical and cosmogical observations promote the fact that 80\% of the matter in the Universe is made of an unknown dark matter weakly interacting with the ordinary matter, the dark matter. However little is known about it, and its nature remains one of the unknown of modern physics. Nowadays the vast majority of the direct detection dark matter experiments didn’t detect anything. The Dark Matter In CCDs (DAMIC) experiment at SNOLAB is one of them, and uses Charged Coupled Devices, silicon semi-conductors, as detectors. My work within the DAMIC collaboration was mainly focused on the construction of the radioactive background model with the GEANT4 toolkit. To start we will introduce the DAMIC at SNOLAB experiment and present the simulation of the experiment, from the generation of primary particle to the simulation of the detector behavior to the energy deposit of the particles simulated. Then I will show you the origins and characteristics of the different radioactive isotopes present in the experiment, information that we retrieved from papers, screening measurement and analysis. To finish I will present the radioactive background model coming from the fit of the simulations to the data and the sensibility of the DAMIC experiment

Recherche de matière sombre légère avec des CCDs de l'expérience DAMIC à Snolab

A large number of astrophysical and cosmogical observations promote the fact that 80\% of the matter in the Universe is made of an unknown dark matter weakly interacting with the ordinary matter, the dark matter. However little is known about it, and its nature remains one of the unknown of modern physics. Nowadays the vast majority of the direct detection dark matter experiments didn’t detect anything. The Dark Matter In CCDs (DAMIC) experiment at SNOLAB is one of them, and uses Charged Coupled Devices, silicon semi-conductors, as detectors. My work within the DAMIC collaboration was mainly focused on the construction of the radioactive background model with the GEANT4 toolkit. To start we will introduce the DAMIC at SNOLAB experiment and present the simulation of the experiment, from the generation of primary particle to the simulation of the detector behavior to the energy deposit of the particles simulated. Then I will show you the origins and characteristics of the different radioactive isotopes present in the experiment, information that we retrieved from papers, screening measurement and analysis. To finish I will present the radioactive background model coming from the fit of the simulations to the data and the sensibility of the DAMIC experiment.De nombreuses observations astrophysiques et cosmologiques tendent à favoriser le fait que 80% de la matière de l’Univers est constitué d’une matière inconnue et interagissant peu avec la matière ordinaire, la matière sombre. Cependant sa nature reste une des inconnues de la physique moderne. Actuellement la vaste majorité des expériences de détection directe de matière sombre n’ont encore rien détecté. L’expérience Dark Matter In CCDs (DAMIC) à SNOLAB est l’une d’entre elles et utilise des Charged Coupled Devices (CCDs, semi-conducteurs en silicium, comme détecteur. Mon travail au sein de la collaboration DAMIC a été centré sur la production d’un modèle de bruit de fond radioactif à l’aide de l’outil GEANT4. On commencera par introduire l’expérience DAMIC à SNOLAB pour présenter la simulation de l’expérience, de la génération des isotopes radioactifs à la simulation de la réponse du détecteur aux dépôts d’énergies des particules simulées. J’exposerai ensuite les origines et caractéristiques des différents isotopes présents dans l’expérience, informations que l’on a obtenues grâce à des mesures dites de screening, des publications et analyses. Pour terminer je présenterais le modèle de bruit de fond radioactif issu de l’ajustement des simulations au données et la sensibilité de l’expérience DAMIC

Kidney and Cardiovascular Effects of Canagliflozin According to Age and Sex: A Post Hoc Analysis of the CREDENCE Randomized Clinical Trial

Rationale & Objective: It is unclear whether the effect of canagliflozin on adverse kidney and cardiovascular events in those with diabetic kid-ney disease varies by age and sex. We assessed the effects of canagliflozin among age group categories and between sexes in the Canagli-flozin and Renal Endpoints in Diabetes with Established Nephropathy Clinical Evaluation (CREDENCE) study.Study Design: Secondary analysis of a random-ized controlled trial. Setting & Participants: Participants in the CREDENCE trial. Intervention: Participants were randomly assigned to receive canagliflozin 100 mg/d or placebo.Outcomes: Primary composite outcome of kid-ney failure, doubling of serum creatinine con-centration, or death due to kidney or cardiovascular disease. Prespecified secondary and safety outcomes were also analyzed. Out-comes were evaluated by age at baseline (<60, 60-69, and >_70 years) and sex in the intention-to-treat population using Cox regression models.Results: The mean age of the cohort was 63.0 & PLUSMN; 9.2 years, and 34% were female. Older age and female sex were independently associ-ated with a lower risk of the composite of adverse kidney outcomes. There was no evidence that the effect of canagliflozin on the primary outcome (acomposite of kidney failure, a doubling of serum creatinine concentration, or death from kidney or cardiovascular causes) differed between age groups (HRs, 0.67 [95% CI, 0.52-0.87], 0.63 [0.4 8-0.82], and 0.89 [0.61-1.29] for ages <60, 60-69, and >_70 years, respectively; P = 0.3 for interaction) or sexes (HRs, 0.71 [95% CI, 0.5 4-0.95] and 0.69 [0.56-0.8 4] in women and men, respectively; P = 0.8 for interaction). No differences in safety outcomes by age group or sex were observed.Limitations: This was a post hoc analysis with multiple comparisons.Conclusions: Canagliflozin consistently reduced the relative risk of kidney events in people with diabetic kidney disease in both sexes and across age subgroups. As a result of greater background risk, the absolute reduction in adverse kidney outcomes was greater in younger participants.Funding: This post hoc analysis of the CREDENCE trial was not funded. The CREDENCE study was sponsored by Janssen Research and Development and was conducted collaboratively by the sponsor, an academic-led steering committee, and an academic research organization, George Clinical.Trial Registration: The original CREDENCE trial was registered at ClinicalTrials.gov with study number NCT02065791

Safety of hospital discharge before return of bowel function after elective colorectal surgery

Background Ileus is common after colorectal surgery and is associated with an increased risk of postoperative complications. Identifying features of normal bowel recovery and the appropriateness for hospital discharge is challenging. This study explored the safety of hospital discharge before the return of bowel function. Methods A prospective, multicentre cohort study was undertaken across an international collaborative network. Adult patients undergoing elective colorectal resection between January and April 2018 were included. The main outcome of interest was readmission to hospital within 30 days of surgery. The impact of discharge timing according to the return of bowel function was explored using multivariable regression analysis. Other outcomes were postoperative complications within 30 days of surgery, measured using the Clavien-Dindo classification system. Results A total of 3288 patients were included in the analysis, of whom 301 (9 center dot 2 per cent) were discharged before the return of bowel function. The median duration of hospital stay for patients discharged before and after return of bowel function was 5 (i.q.r. 4-7) and 7 (6-8) days respectively (P < 0 center dot 001). There were no significant differences in rates of readmission between these groups (6 center dot 6 versus 8 center dot 0 per cent; P = 0 center dot 499), and this remained the case after multivariable adjustment for baseline differences (odds ratio 0 center dot 90, 95 per cent c.i. 0 center dot 55 to 1 center dot 46; P = 0 center dot 659). Rates of postoperative complications were also similar in those discharged before versus after return of bowel function (minor: 34 center dot 7 versus 39 center dot 5 per cent; major 3 center dot 3 versus 3 center dot 4 per cent; P = 0 center dot 110). Conclusion Discharge before return of bowel function after elective colorectal surgery appears to be safe in appropriately selected patients