Explore the vast range of titles available.

Direct numerical simulations are used to investigate the individual dynamics of large spherical particles suspended in a developed homogeneous turbulent flow. A definition of the direction of the particle motion relative to the surrounding flow is introduced and used to construct the mean fluid velocity profile around the particle. This leads to an estimate of the particle slipping velocity and its associated Reynolds number. The flow modifications due to the particle are then studied. The particle is responsible for a shadowing effect that occurs in the wake up to distances of the order of its diameter: the particle calms turbulent fluctuations and reduces the energy dissipation rate compared to its average value in the bulk. Dimensional arguments are presented to draw an analogy between particle effects on turbulence and wall flows. Evidence is obtained for the presence of a logarithmic sublayer at distances between the thickness of the viscous boundary layer and the particle diameter ${D}_{p} $ . Finally, asymptotic arguments are used to relate the viscous sublayer quantities to the particle size and the properties of the outer turbulence. It is shown in particular that the skin-friction Reynolds number behaves as $R{e}_{\\tau } \\propto {({D}_{p} / \\eta )}^{4/ 3} $ .

Dengue is the leading mosquito-borne viral cause of human illness and death. More than four billion people globally are at risk of dengue virus (DENV) infection, and most infections are asymptomatic or present with a non-specific febrile illness. We characterise the first complete DENV-2 genome from Sierra Leone, recovered from a febrile adult who tested RT-PCR–positive. The sequence was identified as DENV-2 genotype II, lineage F.1.1. Phylogenetically, the Sierra Leone genome formed a well-supported sister lineage with a 2024 USA DENV-2 genome; both were nested within but clearly diverged from Indian DENV-2 sequences (2021–2022) and were distinct from the Réunion DENV-2 clade. The degree of genetic divergence was incompatible with a recent or direct import of a South Asian lineage and was more consistent with diversification in an under-sampled Indian Ocean/South Asia network or outside this region in Africa. With a single Sierra Leone genome, the source and extent of local transmission remain unresolved. These findings underscore the benefits of integrating differential diagnostics and genomics into routine care for febrile illness and sustaining regional arboviral surveillance.

Background Chikungunya virus (CHIKV) is a mosquito-borne Alphavirus that has caused several epidemics around the world in recent years. CHIKV is endemic in eastern Senegal, particularly in Kédougou, where epidemiological and virological surveillance is implemented in combination with the 4S network. In August 2023, an outbreak was reported in Kédougou, which rapidly spread to Tambacounda. Epidemiological and virological investigations were carried out in both regions by teams from the Institut Pasteur de Dakar, the WHO, the Africa CDC and the Senegalese Ministry of Health. Methods The team first visited residential areas of confirmed cases, then a definition of suspected cases including socio-demographic aspects and clinical signs was used in an active door-to-door search for other cases. The blood samples were tested for CHIKV infection by real-time RT-PCR and anti-CHIKV IgM ELISA. Continuous variables were described using mean ± SD or median (IQR), and categorical variables as percentages with 95% confidence intervals, with group comparisons via Pearson’s χ 2 or Fisher’s exact test. Kruskal–Wallis tests assessed differences in age across case categories. A multivariate logistic regression (variables with p  < 0.25 in bivariate analysis, manual topdown stepwise selection) was fitted, and model fit evaluated using the Hosmer–Lemeshow test with interaction terms retained at p  < 0.05. Results Out of 1070 blood samples tested, 315 confirmed cases were identified, resulting in an infection rate of 29.4%. There were no deaths. Under 15 and 15–30 age groups, male gender, headache, myalgia, joint pain, asthenia, and retro-orbital pain were among the factors associated with these cases. Conclusions The present study provides clinical and epidemiological characteristics of CHIKV-positive cases, emphasizing the large geographical extension of the epidemic. It outlines the largest chikungunya outbreak documented in Senegal to date, hypothesizes sylvatic transmission, and describes the changing epidemiologic profile of CHIKV. It also stresses that a One-Health strategy is of primary importance in effectively controlling zoonoses.

Abstract Excavations at several archaeological sites in and around Gao have resulted in the recovery of thousands of glass beads presumed to have been acquired from glass bead-producing centers through trade. The bead assemblages cover the period from the eighth to the fourteenth century CE. Here we report on the results of compositional analysis by LA-ICP-MS of 100 beads, permitting comparison with the growing corpus of chemical analyses for glass from African and Near Eastern sites. In this analysis, several compositional groupings are recognized. These include two types of plant-ash soda-lime-silica glass (v-Na-Ca), a mineral soda-lime-silica glass (m-Na-Ca), a high-lime high-alumina (HLHA) glass, a mineral soda-high alumina (m-Na-Al), glass, a plant ash soda-high alumina (v-Na-Al) glass and a high lead composition glass. The reconstruction and dating of depositional contexts suggests a shift in glass sources at the end of the tenth century CE. The issue of source identification is discussed and occurrences at other African sites are mapped, providing new data towards an understanding of trade and exchange networks.

IntroductionThe advent of laparoscopy has significantly reduced the morbidity associated with the majority of abdominal surgeries. In Senegal, the first studies evaluating this technique were published in the 1980s. The objective of this systematic review is to assess the evolution of laparoscopy research in Senegal.MethodsA search of PubMed and Google Scholar was carried out without limit of publication date. The keywords used were “senegal” AND “laparoscop*”. Duplicates were removed, and remaining articles were assessed for selection criteria. We included all articles about laparoscopy published in Senegal. The parameters studied in each included article were the place and year of study, average age, sex ratio, assessed indications and results.Results41 Studies published between 1984 and 2021 met selection criteria. The average age of patients was 33 years (range 4.7–63). The sex ratio was 0.33. The main indications for laparoscopy according to the studies were: benign gastrointestinal disorders in 11 studies (26.8%), abdominal emergencies in 9 studies (22%), gallbladder surgery in 5 studies (12.2%), benign gynecological pathology in 6 studies (14.6%), malignant gynecological pathology in 2 studies (4.9%), diagnostic laparoscopy in 2 studies (4.9%), groin hernia repair in 2 studies (4.9%) and testicular pathology in 1 study (2.4%). Overall mortality was estimated at 0.9% (95% CI 0.6–1.3) and overall morbidity for all complications was estimated at 5% (95% CI 3.4–6.9).ConclusionsThis systematic review showed a predominance of the laparoscopy publications from the capital in Dakar with favorable outcomes. This technique should be popularized in the different regions of the country and its indications expanded.

The novel coronavirus disease 2019 (COVID-19) pandemic has spread from China to the rest of the world. Africa seems less impacted with lower number of cases and deaths than other continents. Senegal recorded its first case on March 2, 2020. We present here data collected from March 2 to October 31, 2020 in Senegal. Socio-demographic, epidemiological, clinical and virological information were collected on suspected cases. To determine factors associated with diagnosed infection, symptomatic disease and death, multivariable binary logistic regression and log binomial models were used. Epidemiological parameters such as the reproduction number and growth rate were estimated. 67,608 suspected cases were tested by the IPD laboratories (13,031 positive and 54,577 negative). All age categories were associated with SARS-CoV-2 infection, but also patients having diabetes or hypertension or other cardiovascular diseases. With diagnosed infection, patients over 65 years and those with hypertension and cardiovascular disease and diabetes were highly associated with death. Patients with co-morbidities were associated with symptomatic disease, but only the under 15 years were not associated with. Among infected, 27.67% were asymptomatic (40.9% when contacts were systematically tested; 12.11% when only symptomatic or high-risk contacts were tested). Less than 15 years-old were mostly asymptomatic (63.2%). Dakar accounted for 81.4% of confirmed cases. The estimated mean serial interval was 5.57 (± 5.14) days. The average reproduction number was estimated at 1.161 (95%CI: 1.159-1.162), the growth rate was 0.031 (95%CI: 0.028-0.034) per day. Our findings indicated that factors associated with symptomatic COVID-19 and death are advanced age (over 65 years-old) and comorbidities such as diabetes and hypertension and cardiovascular disease.

BackgroundCumulative sum (CUSUM) analysis is a valuable tool for quantifying the learning curve of surgical teams by detecting significant changes in operative length. However, there is limited research evaluating the learning curve of laparoscopic techniques in low-resource settings. The objective of this study is to evaluate the learning curve for laparoscopic appendectomy within a single surgical team in Senegal.MethodsThis was a single-center prospective study conducted from May 1, 2018, to August 31, 2023 of patients who underwent laparoscopic appendectomy at a tertiary care institution in West Africa. The AAST classification was used to describe the severity of appendicitis. Parameters studied included age, sex, operative length, conversion rate, and postoperative outcomes. To quantify the learning curve, CUSUM analysis of operative length was performed.ResultsA total of 81 patients were included. The mean age was 26.7 years (range 11–70 years) with a sex ratio of 1.9. Pre-operative severity according to AAST was Grade I in 75.4% (n = 61), Grade III in 7.4% (n = 6), Grade IV in 6.1% (n = 5), and Grade V in 11.1% (n = 9). Conversion occurred in 5 cases (6.1%). The average operative length was 76.8 min (range 30–180 min) and the average length of hospitalization was 2.7 days (range 1–13 days). Morbidity was observed in 3.7% (n = 3) and there were no deaths. The CUSUM analysis showed that a steady operative length was achieved after 28 procedures, with decreasing operative lengths thereafter.ConclusionSurgeons in our setting overcame the learning curve for laparoscopic appendectomy after performing 28 procedures. Moreover, laparoscopic appendectomy is safe and feasible throughout the learning curve. CUSUM analysis should be applied to other laparoscopic procedures and individualized by surgical teams to improve surgical performance and patient outcomes in low-resource settings.

IntroductionLaparoscopy has a clear patient benefit related to postoperative morbidity but may not be as commonly performed in low-and middle-income countries. The decision to convert to laparotomy can be complex and involve factors related to the surgeon, patient, and procedure. The objective of this work is to analyze the factors associated with conversion in laparoscopic surgery in a low-resource setting.MethodsThis is a single-center prospective study of patients who underwent laparoscopic surgery between May 1, 2018 and October 31, 2021. The parameters studied were age, sex, body mass index (BMI), intraoperative complication (e.g., accidental enterotomy, hemorrhage), equipment malfunction (e.g., technical failure of the equipment, break in CO2 supply line), operating time, and conversion rate.ResultsA total of 123 laparoscopic surgeries were performed. The average age of patients was 31.2 years (range 11–75). The procedures performed included appendix procedures (48%), followed by gynecological (18.7%), gallbladder (14.6%), digestive (10.56%), and abdominal procedures (4%). The average length of hospitalization was 3 days (range 1–16). Conversion to laparotomy was reported in 8.9% (n = 11) cases. Equipment malfunction was encountered in 9.8% (n = 12) cases. Surgical complications were noted in 11 cases (8.9%). Risk factors for conversion were shown to be BMI > 25 kg/m2 (OR 4.6; p = 0.034), intraoperative complications (OR 12.6; p = 0.028), and equipment malfunction (OR 9.4; p = 0.002).ConclusionA better understanding of the underlying factors associated with high conversion rates, such as overweight/obesity, intraoperative complications, and equipment failure, is the first step toward surgical planning to reduce postoperative morbidity in low-resource settings.

During the COVID-19 pandemic in Senegal, contact tracing was done to identify transmission clusters, their analysis allowed to understand their dynamics and evolution. In this study, we used information from the surveillance data and phone interviews to construct, represent and analyze COVID-19 transmission clusters from March 2, 2020, to May 31, 2021. In total, 114,040 samples were tested and 2153 transmission clusters identified. A maximum of 7 generations of secondary infections were noted. Clusters had an average of 29.58 members and 7.63 infected among them; their average duration was 27.95 days. Most of the clusters (77.3%) are concentrated in Dakar, capital city of Senegal. The 29 cases identified as super-spreaders, i.e., the indexes that had the most positive contacts, showed few symptoms or were asymptomatic. Deepest transmission clusters are those with the highest percentage of asymptomatic members. The correlation between proportion of asymptomatic and degree of transmission clusters showed that asymptomatic strongly contributed to the continuity of transmission within clusters. During this pandemic, all the efforts towards epidemiological investigations, active case-contact detection, allowed to identify in a short delay growing clusters and help response teams to mitigate the spread of the disease.

Introduction Video feedback, particularly with a head-mounted camera, has previously been described as a useful debriefing tool in well-funded health systems but has never been performed in a low-resource environment. The purpose of this randomized, intervention-controlled study is to evaluate the feasibility of using video feedback with a head-mounted camera during intestinal anastomosis simulation training in a low-resource setting. Methodology This study recruited 14 first-year surgery residents in Senegal, who were randomized into control and camera groups. Both groups received reading materials and video lectures before performing a manual end-to-end intestinal anastomosis using a synthetic model. The control group received oral feedback, while the camera group’s first attempt was recorded, reviewed, and discussed before the second attempt. The primary outcomes were OSATS scores and completion time. Results There were no significant demographic differences between the groups. Both groups showed significant improvement in OSATS scores from the first to the second attempt (control group: p  = 0.002; camera group: p  = 0.0021). The camera group demonstrated a significant reduction in completion time on the second attempt ( p  = 0.0038), unlike the control group ( p  = 0.17). Both groups reported increased confidence in performing the task (control group: p  = 0.003; camera group: p  = 0.0029) and had positive perceptions of the workshop’s effectiveness. Conclusion This pilot study suggests that video feedback with a head-mounted camera is feasible and effective for debriefing during intestinal anastomosis simulation training in a low-resource setting, offering a low-cost, effective way to enhance technical skills. Further research with larger sample sizes is recommended to validate these findings and explore long-term impacts on surgical proficiency.