745 research outputs found

    Improved Bounds on Restricted Isometry Constants for Gaussian Matrices

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    The Restricted Isometry Constants (RIC) of a matrix AA measures how close to an isometry is the action of AA on vectors with few nonzero entries, measured in the ℓ2\ell^2 norm. Specifically, the upper and lower RIC of a matrix AA of size n×Nn\times N is the maximum and the minimum deviation from unity (one) of the largest and smallest, respectively, square of singular values of all (Nk){N\choose k} matrices formed by taking kk columns from AA. Calculation of the RIC is intractable for most matrices due to its combinatorial nature; however, many random matrices typically have bounded RIC in some range of problem sizes (k,n,N)(k,n,N). We provide the best known bound on the RIC for Gaussian matrices, which is also the smallest known bound on the RIC for any large rectangular matrix. Improvements over prior bounds are achieved by exploiting similarity of singular values for matrices which share a substantial number of columns.Comment: 16 pages, 8 figure

    Maternal-fetal prognosis of obstetric emergencies at the maternity ward of the Mamou regional hospital

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    Background: Pregnant women may be at risk of unpredictable obstetric complications such as: bleeding, dystocia, acute fetal suffering, pre-eclampsia and eclampsia. This maternal-fetal prognosis of obstetric emergencies is influenced by factors that are most often related to complications that alter the course or outcome of a pregnancy and require prompt care. The objectives of this study are to analyze the factors that influence the maternal-fetal prognosis of obstetric emergencies; determine their frequency, describe the clinical profiles of patients and evaluate the maternal-fetal prognosis.Methods: The study was conducted at the Mamou Regional Hospital. It was a 6-month quantitative, descriptive and analytical study, from July 1st to December 31st, 2016, including all parturient women whose term is greater than or equal to 28 weeks of amenorrhoea.Results: The study covered 377 obstetric emergencies out of a total of 1273 deliveries, or 29.61%. Factors influencing the prognosis were: young age, parity, unfavorable socio-economic conditions and difficult baseline conditions. The main obstetric emergencies recorded were acute fetal suffering, disproportion and narrowed pelvis. The dominant mode of delivery was caesarean section with a frequency of 89.65%. Maternal lethality is 3.44% and fetal lethality is 5.14%.Conclusions: Obstetric emergency is a frequent situation where better management would improve the prognosis of the mother and fetus

    Cancer in The Gambia: 1988–97

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    We describe the incidence of cancer in The Gambia over a 10-year period using data collected through the Gambian National Cancer Registry. Major problems involved with cancer registration in a developing country, specifically in Africa are discussed. The data accumulated show a low overall rate of cancer incidence compared to more developed parts of the world. The overall age standardized incidence rates (ASR) were 61.0 and 55.7 per 100 000 for males and females, respectively. In males, liver cancer was most frequent, comprising 58% of cases (ASR 35.7) followed by non-Hodgkin lymphoma, 5.4% (ASR 2.4), lung 4.0%, (ASR 2.8) and prostate 3.3% (ASR 2.5) cancers. The most frequent cancers in females were cervix uteri 34.0% (ASR 18.9), liver 19.4% (ASR 11.2), breast 9.2% (ASR 5.5) and ovary 3.2% (ASR 1.6). The data indicate that cancers of the liver and cervix are the most prevalent cancers, and are likely to be due to infectious agents. It is hoped that immunization of children under 1 year against hepatitis B will drastically reduce the incidence of liver cancer in The Gambia. © 2001 Cancer Research Campaign http://www.bjcancer.co

    Holographic Entanglement Entropy at Finite Temperature

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    Using a holographic proposal for the entanglement entropy we study its behavior in various supergravity backgrounds. We are particularly interested in the possibility of using the entanglement entropy as way to detect transitions induced by the presence horizons. We consider several geometries with horizons: the black hole in AdS3AdS_3, nonextremal Dp-branes, dyonic black holes asymptotically to AdS4AdS_4 and also Schwarzschild black holes in global AdSpAdS_p coordinates. Generically, we find that the entanglement entropy does not exhibit a transition, that is, one of the two possible configurations always dominates.Comment: v3: 31 pp, ten figures, modified to match version accepted by IJMP

    The gravity duals of SO/USp superconformal quivers

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    We study the gravity duals of SO/USp superconformal quiver gauge theories realized by M5-branes wrapping on a Riemann surface ("G-curve") together with a Z_2-quotient. When the G-curve has no punctures, the gravity solutions are classified by the genus g of the G-curve and the torsion part of the four-form flux G_4. We also find that there is an interesting relation between anomaly contributions from two mysterious theories: T_{SO(2N)} theory with SO(2N)^3 flavor symmetry and \tilde{T}_{SO(2N)} theory with SO(2N) x USp(2N-2)^2 flavor symmetry. The dual gravity solutions for various SO/USp-type tails are also studied.Comment: 27 pages, 13 figures; v2 minor corrections, typos corrected, Figure 13 replaced, references adde

    Prevalence and awareness of diabetes in Guinea: findings from a WHO STEPS

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    Aims: The aim of the present study was to determine the prevalence of diabetes, and to assess its awareness and related risk factors among adult Guineans.Methods: A population-based cross-sectional survey was conducted on 1 100  adults (46.6% women) aged 35–64 years from Lower Guinea, during September to December 2009, using the WHO STEPwise approach of surveillance of chronic  disease risk factors. Data were collected in three steps: demographic and  behavioural risk factors, blood pressure and anthropometric measurements, and fasting blood cholesterol and glucose testing. A multi-stage cluster sample design was applied to generate nationwide representative data.Results: The mean age of all participants was 47.3 years (SD 8.8), similarly in  Conakry, rural Lower Guinea and urban Lower Guinea. The prevalence of diabetes was 5.7% (95% CI 4.0–8.1). Among participants with diabetes, only 44.0% were aware of their status. In multivariable logistic regression analysis, determinants of diabetes prevalence were urban residency, male sex, age group 45–64 years, increased waist circumference, hypertension and hypercholesterolemia. Male sex, rural residency, age group 45–54 years, no formal education, waist circumference, hypertension and hypercholesterolemia were independent predictors of screen-detected diabetes.Conclusion: The present study found a high prevalence and low awareness of  diabetes, suggesting the need for appropriate actions to strengthen primary  healthcare approaches towards non-communicable diseases in Guinea.Keywords: Diabetes, epidemiology, Guine

    Health-related quality of life among Ebola survivors in Sierra Leone: the role of socio-demographic, health-related and psycho-social factors.

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    BACKGROUND: Evidence of how social factors affect the health-related quality of life (HRQoL) of Ebola virus disease (EVD) survivors is limited. Our study explores the association between socio-demographic, health-related and psycho-social (stigma) factors and EVD survivors' health-related quality of life (HRQoL) in Sierra Leone. METHODS: We conducted a nationwide cross-sectional study among 358 EVD survivors between January and August 2018. We used a multistage sampling method to recruit EVD survivors, and the RAND 36-Item Health Survey item was used to assess the HRQoL. Data were analysed using descriptive statistics and multiple linear regression. RESULTS: When comparing by each dimension in relation to their respective summary scores, role limitation physical [0.00 (50.00)] and role limitation emotional [0.00 (33.33)] were the most affected physical health and mental health domains among EVD survivors respectively. EVD survivors who were older (β = - 3.90, 95% CI - 6.47 to - 1.32, p = 0.003), had no formal education (β = - 2.80, 95% CI - 5.16 to - 0.43, p = 0.021), experienced a unit increase in the number of post-Ebola symptoms (β = - 1.08, 95% CI - 1.74 to - 0.43, p < 0.001) and experienced a unit increase in enacted stigma (β = - 2.61, 95% CI - 4.02 to - 1.20, p < 0.001) were more likely to report a decreased level of physical health. EVD survivors who experienced a unit increase in the time spent in the Ebola treatment centre (β = - 0.60, 95% CI - 0.103 to - 0.18, p = 0.006) and those who experienced a unit increase in enacted Stigma were more likely to report decreased levels of mental health (β = - 1.50, 95% CI - 2.67 to - 0.33, p = 0.012). CONCLUSION: Sociodemographic, health-related, and psycho-social factors were significantly associated with decrease levels of HRQoL. Our findings improve our understanding of the factors that might influence the HRQoL and suggest the need for EVD survivors to be provided with a comprehensive healthcare package that caters for their physical and mental health needs
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