Experimental and Theoretical Search for a Phase Transition in Nuclear Fragmentation

Phase transitions of small isolated systems are signaled by the shape of the caloric equation of state e^*(T), the relationship between the excitation energy per nucleon e^* and temperature. In this work we compare the experimentally deduced e^*(T) to the theoretical predictions. The experimentally accessible temperature was extracted from evaporation spectra from incomplete fusion reactions leading to residue nuclei. The experimental e^*(T) dependence exhibits the characteristic S-shape at e^* = 2-3 MeV/A. Such behavior is expected for a finite system at a phase transition. The observed dependence agrees with predictions of the MMMC-model, which simulates the total accessible phase-space of fragmentation

Incomes and Food Security Management in rural areas of Burkina Faso

Food security is traditionally analyzed using one or the other of the four (4) dimensions that are availability, accessibility, quality and stability. The existing empirical analyzes classify households in two situations (food security and food insecurity) through a threshold they set. However, classifying households to two situations is very limited because it does not reflect the actual situation of households. Moreover, in the analysis of the determinants of food insecurity, qualitative models used by empirical investigations generate loss of information. To address these difficulties, the fuzzy set theory and Tobit model are two complementary approaches to identify households facing food insecurity and find its determinants. This methodology will be adopted to measure the impact of incomes management on food insecurity in rural areas in Burkina Faso. Keywords: Food insecurity, fuzzy sets theory, Tobit model, Burkina Faso

Faecal carriage of multi-drug resistant Enterobacteriaceae in hospitalized children at University Teaching Hospital Sylvanus Olympio of Lomé, Togo

Background: High prevalence of infections and associated antibiotherapy may put children at increased risk for development of multidrug-resistance (MDR), mostly to bacterial infections. The objective of this study therefore was to determine the prevalence of gastrointestinal carriage of MDR Enterobacteriaceae among hospitalized children in the Paediatric department of Sylvanus Olympio University Hospital, Lomé, Togo.Methodology: A descriptive cross-sectional study was carried out on randomly selected hospitalized children in the Paediatric wards of the hospital from November 03 to November 10, 2020, after obtaining informed consent from their parents/guardians. Rectal swabs and stool samples were collected from each participant and cultured for isolation of members of the family Enterobacteriaceae on Hektoen enteric agar containing 4 µg/L cefotaxime, which was incubated aerobically at 37oC for 24 hours. The isolates were identified using in-house biochemical tests. Antibiotic susceptibility test (AST) of each isolate to a panel of antibiotics including ertapenem and imipenem was done by the disc diffusion method and interpreted according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) clinical breakpoints version 2020 V.1.1. ESBL production was detected by the double-disc synergy test of amoxicillin and clavulanic acid, and resistance to carbapenem was inferred by resistance to ertapenem and imipenem discs in the AST. Multi-drug resistance (MDR) was defined as resistance to at least three families of antibiotics. Statistical analysis of data was carried out on Excel 2010 and EPI INFO 7.2 and p value < 0.05 was considered to be statistical significance. Results: A total of 70 hospitalized children during the study period were randomly recruited with an average age of 4 years 3 days and a range of 1 day to 18 years. The male gender was predominant (54.3%) with a M: F ratio of 1.2. Samples were culture positive in 85.7% (60/70) and a total of 72 species of Enterobacteriaceae were isolated in 93.3% (56/60) of these cultures. Escherichia coli was the most frequently isolated species(56.9%, 41/72). More than 90% (65/72) of the isolates were resistant to ampicillin, 58.3% (42/72) to third generation cephalosporins, 59.7% (43/72) to fourth generation cephalosporins, 43% (31/72) to aminoglycosides, 55.6% (40/72) were multi-drug resistant, 48.6% (35/72) were ESBL-producing strains, and 6.9% (5/72) were carbapenem resistant. Eighty-three percent (29/35) of ESBL-producing and all the carbapenem resistant isolates (5/5) were recovered from children on antibiotic therapy. The prevalence of ESBL-producing phenotypes among culture-positive children on antibiotic treatment (72.5%, 29/40) was significantly higher than among culture-positive children not on antibiotic treatment (20.0%, 4/20), indicating that antibiotic therapy was significantly associated with carriage of MDR isolates (OR=10.545, 95% CI=2.882-38.590, p=0.0002). Conclusion: The high faecal carriage rate of MDR Enterobacteriaceae, which are all ESBL-producing strains, in this study is worrying. There is urgent need to develop measures to monitor and limit the spread of these MDR organisms in children and the community in Togo

Assessment of the performance of six in vitro diagnostic kits for qualitative detection of hepatitis B virus surface antigen (HBsAg) in human serum or plasma in Lomé, Togo

Background: Several in vitro diagnostic (IVD) test kits for hepatitis B surface antigen (HBsAg) are commercially available. The question is whether they are performing well for both screening and diagnosis or not? Thus, this study aimed to evaluate the performance of six commercially available HBsAg detection kits in Togo. Methods: This study was conducted at the National Reference Center for HIV/STI testing in Lomé (CNR-VIH/IST), Togo. Reference sera used for the assessment were collected from blood donors and patients with history of hepatitis B viral (HBV) infection between 2008 and 2014, and includes 200 non-reactive HBsAg and 150 reactive HBsAg sera that were confirmed with a reference method which consisted of the combination of an ELISA, a RDT, and a molecular test. Four ELISA kits (EKOlab ELISA-HBsAg; HEPALISA ULTRA; HEPALISA; Murex AgHBs Version 3) and two RDTs kits (ACON AgHBs and OnSite HBsAg Rapid Test-Cassette) were then evaluated using these serum samples. The EPI-INFO software version 7.2 was used to determine the 95% confidence interval and performed statistical analysis. Results: Reference serum samples were collected from the population with 65.0% under 40 years of age and 61.2% males. The sensitivity of the 4 ELISA tests compared to the reference method was 100%. Apart from the HEPALISA test with a specificity of 100.0%, the specificity of the other three ELISA tests (Murex HBsAg version 3, HEPALISA ULTRA and EKOlab ELISA-HBsAg) were 98.4%, 97.3% and 91.8% respectively. For the RDTs, the sensitivity of ACON HBsAg and OnSite HBsAg Rapid Test-Cassette was 70.0% and 95.6% respectively while the specificity was 100.0% for both. Conclusion: The ELISA tests evaluated were more sensitive than the RDTs, and HEPALISA test was the most efficient. Of the two RDTs, the OnSite HBsAg Rapid Test-Cassette was more sensitive. Our findings highlight the need for onsite verification of in vitro diagnostic kits for qualitative detection of hepatitis B surface antigen before their routine use in Togo. Keywords: HBV, HBsAg, Performance, IVD tes

High faecal carriage of extended-spectrum beta-lactamase producing Enterobacteriaceae (ESBL-PE) among hospitalized patients at Sylvanus Olympio Teaching Hospital, Lomé, Togo in 2019

Background: Extended-spectrum beta-lactamase producing Enterobacteriaceae (ESBL-PE) are a global health concern, associated with increased morbidity and mortality. Even in the absence of infections, colonization by these pathogens is still a great threat because of the risk of cross transfer among hospitalized patients. Faecal carriage of ESBL-PE remained poorly documented in Africa. This study aimed to determine faecal carriage rate of ESBL-PE, factors associated with carriage, and antimicrobial susceptibility of the strains among hospitalized patients at Sylvanus Olympio Teaching Hospitals (CHU SO) in Lomé, Togo. Methodology: This was a cross-sectional study of 105 randomly selected hospitalized patients between September and November 2019. Socio-demographic and clinical data as well as rectal swabs were collected after obtaining the consent of the selected participants. Rectal swabs were cultured on selective bromocresol purple (BCP) lactose agar containing 6µg/l ceftazidime, for isolation of Enterobacteriaceae. Identification of each isolate was performed using Uriselect 4 medium and API 20E. Antibiotic susceptibility of the bacterial isolates was performed by the Bauer-Kirby agar disc diffusion test and interpreted according to CASFM-EUCAST recommendations. Results: The faecal carriage rate of ESBL-PE among selected hospitalized patients was 80.9% (85/105). Escherichia coli was the most frequent bacteria 69.5% (73/105), followed by Klebsiella pneumoniae 22.8% (24/105). The antibiotic profile of ESBL producing Escherichia coli showed resistance to amoxycillin+clavulanic acid (72.6%), ticarcillin+clavulanic acid (82.2%), piperacillin+tazobactam (30.1%), cefoxitin (30.1%) ciprofloxacin (84.9%), levofloxacin (76.7%), nalidixic acid (83.6%), chloramphenicol (26.0%), gentamicin (49.3%), sulfamethoxazole-trimethoprim (86.3%), imipenem (5.5%), and ertapenem (21.9%). All (100%) isolates were sensitive to amikacin and fosfomycin. None of the characteristics or risk factors assessed was significantly associated with faecal carriage of ESBL-PE. Conclusion: Faecal carriage rate of ESBL-PE in these hospitalized patients was very high, but no factor was associated with carriage of ESBL-PE among the study population. Implementation of infection control measures, and surveillance are needed to limit the spread of these resistant pathogens within CHU SO healthcare facilities

Hepatitis B infection in HIV-1-infected patients receiving highly active antiretroviral therapy in Lomé, Togo: Prevalence and molecular consequences

Background. No data are available on HIV/hepatitis B virus (HBV) or hepatitis C virus coinfection in Togo, and patients are not routinely tested for HBV infection.Objectives. To determine the prevalence of HBV and the risk of HBV drug resistance during antiretroviral treatment in HIV-coinfected patients in Togo.Method. This cross-sectional study was carried out in Lomé, Togo, from January 2010 to December 2011 among HIV-infected patients who had been on antiretroviral therapy (ART) for at least 6 months.Results. In total, 1 212 patients (74.9% female) living with HIV/AIDS and treated with ART were included in the study. The seroprevalence of hepatitis B surface antigen (HBsAg) was 9.7% (117/1 212; 95% confidence interval (CI) 8.04 - 11.45). Of these 117 HBsAg-positive patients, 16 (13.7%) were hepatitis B e antigen (HBeAg)-positive, and 115 (98.3%) were on lamivudine. The HBV DNA load was >10 IU/ mL in 33/117 patients overall (38%), and in 87.5% of 16 HBeAg positive patients (p<0.0001). In multivariate analysis, factors associated with HBV DNA load >10 IU/mL were HBeAg positivity (adjusted odds ratio (aOR) 6.4; p=0.001) and a higher level of education (aOR 6.5; p=0.026). The prevalence of HBV resistance to lamivudine was 13.0% (15/115; 95% CI 7.0 - 19.0). The detected resistance mutations were rtL180M (14/15 patients) and rtM204V/I (15/15).Conclusion. The seroprevalence of HBV among ART-treated HIV-infected patients in Togo was 9.7%. The prevalence of HBV lamivudine resistance mutations after 2 years of ART was 13.0%. These results suggest that HBV screening before ART initiation can be based on HBsAg testing

Baited-boats : an innovative way to control riverine tsetse, vectors of sleeping sickness in West Africa

Background: Human African Trypanosomiasis (HAT) is an important neglected tropical disease caused by Trypanosoma spp. parasites transmitted by species of tsetse fly (Glossina spp). The most important vectors of HAT are riverine tsetse and these can be controlled by attracting them to stationary baits such as insecticide-impregnated traps or targets deployed along the banks of rivers. However, the geographical nature of some riverine habitats, particularly mangroves but also extensive lake and river networks, makes deployment of baits difficult and limits their efficacy. It is known that tsetse are attracted by the movement of their hosts. Our hypothesis was that mounting a target on canoes typically used in Africa ('pirogues') would produce an effective means of attracting-and-killing riverine tsetse in extensive wetland habitats. Methods: In Folonzo, southern Burkina Faso, studies were made of the numbers of tsetse attracted to a target (75 x 50 cm) of blue cloth and netting mounted on a pirogue moving along a river, versus the same target placed on the riverbank. The targets were covered with a sticky film which caught tsetse as they contacted the target. Results: The pirogue-mounted target caught twice as many G. tachinoides and G. p. gambiensis, and 8 times more G. morsitans submorsitans than the stationary one (P < 0.001). Conclusion: Pirogues are common vehicle for navigating the rivers, lakes and swamps of West Africa. The demonstration that tsetse can be attracted to targets mounted on such boats suggests that pirogues might provide a cost-effective and convenient platform for deploying targets to control tsetse in the mangrove systems of West Africa where HAT persists. Further studies to assess the impact of pirogue-mounted targets on tsetse populations in HAT foci and the protective value of targets for pirogue passengers are recommended

Investigation of the thermal stability of Mg/Co periodic multilayers for EUV applications

We present the results of the characterization of Mg/Co periodic multilayers and their thermal stability for the EUV range. The annealing study is performed up to a temperature of 400\degree C. Images obtained by scanning transmission electron microscopy and electron energy loss spectroscopy clearly show the good quality of the multilayer structure. The measurements of the EUV reflectivity around 25 nm (~49 eV) indicate that the reflectivity decreases when the annealing temperature increases above 300\degreeC. X-ray emission spectroscopy is performed to determine the chemical state of the Mg atoms within the Mg/Co multilayer. Nuclear magnetic resonance used to determine the chemical state of the Co atoms and scanning electron microscopy images of cross sections of the Mg/Co multilayers reveal changes in the morphology of the stack from an annealing temperature of 305\degreee;C. This explains the observed reflectivity loss.Comment: Published in Applied Physics A: Materials Science \& Processing Published at http://www.springerlink.com.chimie.gate.inist.fr/content/6v396j6m56771r61/ 21 page

Neemazal ® as a possible alternative control tool for malaria and African trypanosomiasis?

Background: Research efforts to identify possible alternative control tools for malaria and African trypanosomiasis are needed. One promising approach relies on the use of traditional plant remedies with insecticidal activities. Methods: In this study, we assessed the effect of blood treated with different doses of NeemAzal ® (NA, neem seed extract) on mosquitoes (Anopheles coluzzii) and tsetse flies (Glossina palpalis gambiensis) (i) avidity to feed on the treated blood, (ii) longevity, and (iii) behavioural responses to human and calf odours in dual-choice tests. We also gauged NeemAzal ® toxicity in mice. Results: In An. coluzzii, the ingestion of NA in bloodmeals offered by membrane feeding resulted in (i) primary antifeedancy; (ii) decreased longevity; and (iii) reduced response to host odours. In G. palpalis gambiensis, NA caused (i) a knock-down effect; (ii) decreased or increased longevity depending on the dose; and (iii) reduced response to host stimuli. In both cases, NA did not affect the anthropophilic rate of activated insects. Overall, the most significant effects were observed with NA treated bloodmeals at a dose of 2000 μg/ml for mosquitoes and 50 μg/ml for tsetse flies. Although no mortality in mice was observed after 14 days of follow-up at oral doses of 3.8, 5.6, 8.4 and 12.7 g/kg, behavioural alterations were noticed at doses above 8 g/kg. Conclusion: This study revealed promising activity of NA on A. coluzzii and G. palpalis gambiensis but additional research is needed to assess field efficacy of neem products to be possibly integrated in vector control programmes