Improved Bounds on Restricted Isometry Constants for Gaussian Matrices

The Restricted Isometry Constants (RIC) of a matrix $A$ measures how close to an isometry is the action of $A$ on vectors with few nonzero entries, measured in the $\ell^2$ norm. Specifically, the upper and lower RIC of a matrix $A$ of size $n\times N$ is the maximum and the minimum deviation from unity (one) of the largest and smallest, respectively, square of singular values of all ${N\choose k}$ matrices formed by taking $k$ columns from $A$. 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 $(k,n,N)$. 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

Factors that influenced utilization of antenatal and immunization services in two local government areas in The Gambia during COVID-19: An interview-based qualitative study.

INTRODUCTION: Evidence is being consolidated that shows that the utilization of antenatal and immunization services has declined in low-income countries (LICs) during the COVID-19 pandemic. Very little is known about the effects of the pandemic on antenatal and immunization service utilization in The Gambia. We set out to explore the COVID-19-related factors affecting the utilization of antenatal and immunization services in two Local Government Areas (LGAs) in The Gambia. METHODS: A qualitative methodology was used to explore patients' and providers' experiences of antenatal and immunization services during the pandemic in two LGAs in The Gambia. Thirty-one study participants were recruited from four health facilities, applying a theory-driven sampling framework, including health workers as well as female patients. Qualitative evidence was collected through theory-driven semi-structured interviews, and was recorded, translated into English, transcribed, and analysed thematically, applying a social-ecological framework. RESULTS: In our interviews, we identified themes at five different levels: individual, interpersonal, community, institutional and policy factors. Individual factors revolved around patients' fear of being infected in the facilities, and of being quarantined, and their anxiety about passing on infections to family members. Interpersonal factors involved the reluctance of partners and family members, as well as perceived negligence and disrespect by health workers. Community factors included misinformation within the community and mistrust of vaccines. Institutional factors included the shortage of health workers, closures of health facilities, and the lack of personal protective equipment (PPEs) and essential medicines. Finally, policy factors revolved around the consequences of COVID-19 prevention measures, particularly the shortage of transport options and mandatory wearing of face masks. CONCLUSIONS: Our findings suggest that patients' fears of contagion, perceptions of poor treatment in the health system, and a general anxiety around the imposing of prevention measures, undermined the uptake of services. In future emergencies, the government in The Gambia, and governments in other LICs, will need to consider the unintended consequences of epidemic control measures on the uptake of antenatal and immunization services

Invasive bacterial infections in Gambians with sickle cell anaemia in an era of widespread Pneumococcal and Haemophilus influenzae type B vaccination

Background: There is relatively little data on the aetiology of bacterial infections in patients with sickle cell anaemia (SCA) in West Africa, and no data from countries that have implemented conjugate vaccines against both Streptococcus pneumoniae and Haemophilus influenzae type b (Hib). Methods: We conducted a retrospective analysis of SCA patients admitted to the Medical Research Council Unit, The Gambia during a five-year period when there was high coverage of Hib and Pneumococcal conjugate vaccination. We evaluated 161 admissions of 126 patients between April 2010 and April 2015. Results: Pathogenic bacteria were identified in blood cultures from 11 of the 131 admissions that had cultures taken (8.4%, 95% CI 4.5-14.1%). The most frequent isolate was Salmonella Typhimurium (6/11; 54.5%), followed by Staphylococcus aureus (2/11; 18.2%) and other enteric Gram-negative pathogens (2/11; 18.2%) and there was one case of H. influenzae non-type b bacteraemia (1/11; 9.1%). There were no episodes of bacteraemia caused by S. pneumoniae or Hib. Conclusions: The low prevalence of S. pneumoniae and Hib, and the predominance of non-typhoidal Salmonella as a cause of bacteraemia suggest the need to reconsider optimal antimicrobial prophylaxis and the empirical treatment regimens for patients with SCA

Variations in agronomic and grain quality traits of rice grown under irrigated lowland conditions in West Africa

Rice breeding in West Africa has been largely skewed toward yield enhancement and stress tolerance. This has led to the variable grain quality of locally produced rice in the region. This study sought to assess variations in the agronomic and grain quality traits of some rice varieties grown in this region, with a view to identifying sources of high grain yield and quality that could serve as potential donors in their breeding programs. Forty‐five varieties were grown under irrigated conditions in Benin and Senegal with two trials in each country. There were wide variations in agronomic and grain quality traits among the varieties across the trials. Cluster analysis using paddy yield, head rice yield, and chalkiness revealed that 68% of the total variation could be explained by five varietal groupings. One group comprising seven varieties (Afrihikari, BG90‐2, IR64, Sahel 108, WAT311‐WAS‐B‐B‐23‐7‐1, WAT339‐TGR‐5‐2, and WITA 10) had high head rice yield and low chalkiness. Of the varieties in this group, Sahel 108 had the highest paddy yield in three of the four trials. IR64 and Afrihikari had intermediate and low amylose content, respectively, with the rest being high‐amylose varieties. Another group of varieties consisting of B6144F‐MR‐6‐0‐0, C74, IR31851‐96‐2‐3‐2‐1, ITA222, Jaya, Sahel 305, WITA 1, and WITA 2 had high paddy yield but poor head rice yield and chalkiness. The use of materials from these two groups of varieties could accelerate breeding for high yielding rice varieties with better grain quality for local production in West Africa

Referencing for nursing, health, and social care undergraduates; what do students understand and what do academics know?

Accurate referencing is a key tenet of academic work for all disciplines, though not all nursing, health and social care students consistently apply principles during their studies (Froste 2020; Lynch et al 2016). This can hinder a student’s academic achievement, with professional implications should practice fall far below expected standards (HCPC 2016; NMC 2023). Universities produce resources and signpost guides for students on referencing, though despite this practice remains sub optimal. This project is designed to uncover what nursing, health and social care students know about referencing and what academic staff teaching these students, think students know about referencing

Involvement of the general public in the management of water pollution in Johor Bahru Malaysia

Water is undoubtedly the most delicate component of the ecosystem, but it is essential for human and industrial advancement. As the population grows, so does the demand for water supplies and drinkable water. Water covers roughly 71percent of the total earth’s surface and highly vital natural resource for humans. However, only 2.5 percent of the world's water is pure and thus drinkable. It is everyone's fundamental human right to have access to clean water. The purpose of this study is: to identify the current level of public involvement in water pollution management and to assess people's desire to participate towards reducing water pollution. The study's methodology is a quantitative approach for achieving the research objectives. A total of sixty-three (63) responses were reordered from the distribution of the questionnaires. The data collected were analysed using Microsoft Excel (2019) and simple percentage distribution tables and charts. The findings revealed that most of the participants have sewerage connections in their residences and that the water quality of their rivers is acceptable for majority of the participants. The study also indicated that water pollution is a grave concern for environmental and social health. In addition, it was observed that community involvement in water pollution decision-making processes was currently low on average, implying that authorities still have room to improve concerning water pollutant information delivery. Majority of respondents agreed that investing more money in water and waste management, and educating the public, are strategies to enhance water quality. Eventually, the findings revealed that the general public is enthusiastic about taking part in the fight against water pollution and are ready to participate in water pollution management in their community. The study recommends building a solid foundation to allow greater public involvement in decision-making and to enacting strict water pollution control policy

A double blind randomised controlled trial comparing standard dose of iron supplementation for pregnant women with two screen-and-treat approaches using hepcidin as a biomarker for ready and safe to receive iron.

WHO recommends daily iron supplementation (60mg) for all pregnant women where anaemia prevalence exceeds 40%. However, recent evidence suggests that iron supplementation may be harmful as it increases the risks of hypertension and of infection. Iron absorption is regulated by hepcidin, a key iron regulatory hormone with the potential to be a useful marker to determine if oral iron can be absorbed effectively and safely. We aimed to identify a hepcidin threshold to define ’safe and ready’ to receive iron and then test whether a hepcidin-guided screen-and-treat approach to iron supplementation is non-inferior to the WHO-recommended universal daily supplementation. Method: We established our screening threshold by measuring haemoglobin and serum hepcidin, ferritin, iron, soluble transferrin receptor (sTfR), and C-reactive protein (CRP) at 14, 20 and 30 week of gestation among 395 pregnant rural Gambian women using archived maternal blood samples (2010-2013), and analysed hepcidin’s diagnostic test accuracy [area under the receiver operating characteristic curve (AUCROC), sensitivity, specificity, cut offs] for iron deficiency at each time point. We established a threshold of 2.5μg/L. We then conducted a 3-arm randomised-controlled proof-of-concept trial in rural Gambia from June 2014 to March 2016. We recruited 498 pregnant women aged 18-45 years with 14-22 weeks gestation to receive either: (A) UNU/UNICEF/WHO international multiple micronutrient preparation (UNIMMAP) containing iron 60mg/d; (B) UNIMMAP containing iron 60mg/d but based on a weekly hepcidin screening 4.4mg/L and hepcidin <2.5μg/L were lower in the Reference arm. The Screen-and-treat approaches had no added advantage than universal daily iron supplementation in terms of adherence, side effects or safety outcomes. Conclusion: The daily 60mg iron supplementation arm performed better than both screen-and-treat arms for anaemia and other iron markers (hepcidin, ferritin, soluble transferrin receptor, transferrin saturation). We therefore found no support for a screen-and-treat iron supplementation based on hepcidin concentration <2.5μg/L in pregnant Gambian women