Papers by souleymane diallo
Bulletin of the American …, 2009
We report new measurements of the Bose-Einstein condensate fraction in solid helium. The goal is ... more We report new measurements of the Bose-Einstein condensate fraction in solid helium. The goal is to reveal whether there is BEC associated with the superfluid fractions that have been observed in solid helium [1,2]. The condensate fraction, n$_0$, is obtained from neutron scattering ...
IEEE Photonics Journal
Kerr optical frequency combs have found various applications in science and technology, and minim... more Kerr optical frequency combs have found various applications in science and technology, and minimizing their pump power has become an important area of research. These combs are generated using a wide variety of platforms, with a size ranging from micrometers to millimeters, and quality factors ranging from millions to billions. It is therefore not trivial to assess the pump power requirements for comb generation when they have such a large diversity in terms of resonator properties and pump configurations. We propose a suitably normalized threshold pump power as a metric to optimize Kerr comb generation independently of the platform. This method allows one to evaluate the minimum threshold power solely based on the properties of the bare resonator, and independently of dispersion, detuning or coupling considerations. In order to confirm the validity of this approach, we experimentally demonstrate Kerr comb generation in a millimeter-size magnesium fluoride whispering-gallery mode resonator with a threshold pump power of only 1.2 mW, which is one of the lowest pump powers reported to date for a mm-size resonator.
Biomolecules, 2021
Olfaction is orchestrated at different stages and involves various proteins at each step. For exa... more Olfaction is orchestrated at different stages and involves various proteins at each step. For example, odorant-binding proteins (OBPs) are soluble proteins found in sensillum lymph that might encounter odorants before reaching the odorant receptors. In tsetse flies, the function of OBPs in olfaction is less understood. Here, we investigated the role of OBPs in Glossina fuscipes fuscipes olfaction, the main vector of sleeping sickness, using multidisciplinary approaches. Our tissue expression study demonstrated that GffLush was conserved in legs and antenna in both sexes, whereas GffObp44 and GffObp69 were expressed in the legs but absent in the antenna. GffObp99 was absent in the female antenna but expressed in the male antenna. Short odorant exposure induced a fast alteration in the transcription of OBP genes. Furthermore, we successfully silenced a specific OBP expressed in the antenna via dsRNAi feeding to decipher its function. We found that silencing OBPs that interact with 1-o...
The quantum properties of optical frequency combs have been the focus of several research works i... more The quantum properties of optical frequency combs have been the focus of several research works in recent years. Investigating the quantum correlations between the spectral components of the combs is of fundamental interest because it allows for a better understanding of light-matter interactions, but also of technological interest as it wold permits the implementation of quantum communication networks. In this communication, we present some of our latest advances in this field.
Frontiers in Cellular Neuroscience, 2020
Insects that transmit many of the world's deadliest animal diseases, for instance trypanosomosis,... more Insects that transmit many of the world's deadliest animal diseases, for instance trypanosomosis, find their suitable hosts and avoid non-preferred hosts mostly through olfactory cues. The waterbuck repellent blend (WRB) comprising geranylacetone, guaiacol, pentanoic acid, and δ-octalactone derived from waterbuck skin odor is a repellent to some savannah-adapted tsetse flies and reduces trap catches of riverine species. However, the cellular and molecular mechanisms associated with detection and coding of the repellent odors remain to be elucidated. Here, we demonstrated that WRB inhibited blood feeding in both Glossina pallidipes Austen, 1903 and Glossina fuscipes fuscipes Newstead, 1910. Using the DREAM (Deorphanization of Receptors based on Expression Alterations in odorant receptor mRNA levels) technique, combined with ortholog comparison and molecular docking, we predicted the putative odorant receptors (ORs) for the WRB in G. f. fuscipes, a non-model insect. We show that exposure of G. f. fuscipes in vivo to WRB odorant resulted in up-and downregulation of mRNA transcript of several ORs. The WRB component with strong feeding inhibition altered mRNA transcript differently as compared to an attractant odor, showing these two odors of opposing valence already segregate at the cellular and molecular levels. Furthermore, molecular dynamics simulations demonstrated that the predicted ligand-OR binding pockets consisted mostly of hydrophobic residues with a few hydrogen bonds but a stable interaction. Finally, our electrophysiological response showed the olfactory sensory neurons of G. f. fuscipes tuned to the tsetse repellent components in different sensitivity and selectivity.
Scientific Reports, 2020
In recent years Bamako has been faced with an emerging threat from multidrug resistant TB (MDR-TB... more In recent years Bamako has been faced with an emerging threat from multidrug resistant TB (MDR-TB). Whole genome sequence analysis was performed on a subset of 76 isolates from a total of 208 isolates recovered from tuberculosis patients in Bamako, Mali between 2006 and 2012. Among the 76 patients, 61(80.3%) new cases and 15(19.7%) retreatment cases, 12 (16%) were infected by MDR-TB. The dominant lineage was the Euro-American lineage, Lineage 4. Within Lineage 4, the Cameroon genotype was the most prevalent genotype (n = 20, 26%), followed by the Ghana genotype (n = 16, 21%). A sub-clade of the Cameroon genotype, which emerged ~22 years ago was likely to be involved in community transmission. A sub-clade of the Ghana genotype that arose approximately 30 years ago was an important cause of MDR-TB in Bamako. The Ghana genotype isolates appeared more likely to be MDR than other genotypes after controlling for treatment history. We identified a clade of four related Beijing isolates tha...
BMC research notes, Jan 6, 2017
Drug resistant tuberculosis presents a major public health challenge. We present here the first t... more Drug resistant tuberculosis presents a major public health challenge. We present here the first two patients diagnosed with extensively drug resistant tuberculosis in Bamako, Mali. Genotypic findings suggest possible nosocomial transmission from the first patient to the second one, resulting in superinfection of the second patient. After being diagnosed with extensively drug resistant tuberculosis in August 2016, the patients only started receiving appropriate treatment 10Â months later. The identification of these patients highlights the need for improved diagnostic and treatment algorithms for better surveillance and management of drug resistance in Mali. In the interest of these as well as future patients suffering from resistant tuberculosis, all steps recommended for programmatic management of drug resistant tuberculosis must be urgently prioritized in order to strengthen the multidrug resistant tuberculosis program.
International journal of mycobacteriology
To identify strains of Mycobacterium tuberculosis complex (MTBc) circulating in Bamako region dur... more To identify strains of Mycobacterium tuberculosis complex (MTBc) circulating in Bamako region during the past 10 years. From 2006 to 2016, we conducted a cross-sectional study to identify with spoligotyping, clinical isolates from tuberculosis (TB)-infected patients at different stages of their treatments in Bamako, Mali. Among the 904 suspected TB patients included in the study and thereafter tested in our BSL-3 laboratory, 492 (54.4%) had MTBc and therefore underwent spoligotyping. Overall, three subspecies, i.e., MTB T1 (31.9%) and MTB LAM10 (15.3%) from lineage 4 and M. africanum 2 (16.8%) from lineage 6 were the leading causes of TB in Bamako region during the past 10 years. Other spoligotypes such as MTB T3, MTB Haarlem 2, MTB EAI3, and MTB family 33 were also commonly seen from 2010 to 2016. This study showed a high genetic diversity of strains isolated in Bamako region and highlights that M. tuberculosis T1 strain was the most prevalent. Furthermore, the data indicate an inc...
The American journal of tropical medicine and hygiene, 2017
Pneumonia is the leading cause of death in children. The objectives were to evaluate the microbio... more Pneumonia is the leading cause of death in children. The objectives were to evaluate the microbiological agents linked with hypoxemia in hospitalized children with pneumonia from developing countries, to identify predictors of hypoxemia, and to characterize factors associated with in-hospital mortality. A multicenter, observational study was conducted in five hospitals, from India (Lucknow, Vadu), Madagascar (Antananarivo), Mali (Bamako), and Paraguay (San Lorenzo). Children aged 2-60 months with radiologically confirmed pneumonia were enrolled prospectively. Respiratory and whole blood specimens were collected, identifying viruses and bacteria by real-time multiplex polymerase chain reaction (PCR). Microbiological agents linked with hypoxemia at admission (oxygen saturation < 90%) were analyzed by multivariate logistic regression, and factors associated with 14-day in-hospital mortality were assessed by bivariate Cox regression. Overall, 405 pneumonia cases (3,338 hospitalizatio...
Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, Aug 12, 2017
Pneumonia, the leading infectious cause of child mortality globally, mainly afflicts developing c... more Pneumonia, the leading infectious cause of child mortality globally, mainly afflicts developing countries. This prospective observational study aimed to assess the microorganisms associated with pneumonia in children aged <5 years in developing and emerging countries. A multicenter, case-control study by the GABRIEL (Global Approach to Biological Research, Infectious diseases and Epidemics in Low-income countries) network was conducted between 2010 and 2014 in Cambodia, China, Haiti, India (2 sites), Madagascar, Mali, Mongolia, and Paraguay. Cases were hospitalized children with radiologically confirmed pneumonia; controls were children from the same setting without any features suggestive of pneumonia. Nasopharyngeal swabs were collected from all subjects; 19 viruses and 5 bacteria were identified by reverse-transcription polymerase chain reaction. Associations between microorganisms and pneumonia were quantified by calculating the adjusted population attributable fraction (aPAF...
PLOS ONE, 2017
The worldwide dissemination of extended-spectrum beta-lactamase producing Enterobacteriaceae, (ES... more The worldwide dissemination of extended-spectrum beta-lactamase producing Enterobacteriaceae, (ESBL-E) and their subset producing carbapenemases (CPE), is alarming. Limited data on the prevalence of such strains in infections from patients from Sub-Saharan Africa are currently available. We determined, here, the prevalence of ESBL-E/CPE in bacteriemic patients in two teaching hospitals from Bamako (Mali), which are at the top of the health care pyramid in the country. During one year, all Enterobacteriaceae isolated from bloodstream infections (E-BSI), were collected from patients hospitalized at the Point G University Teaching Hospital and the pediatric units of Gabriel Touré University Teaching Hospital. Antibiotic susceptibility testing, enzyme characterization and strain relatedness were determined. A total of 77 patients had an E-BSI and as many as 48 (62.3%) were infected with an ESBL-E. ESBL-E BSI were associated with a previous hospitalization (OR 3.97 95% IC [1.32; 13.21]) and were more frequent in hospital-acquired episodes (OR 3.66 95% IC [1.07; 13.38]). Among the 82 isolated Enterobacteriaceae, 58.5% were ESBL-E (20/31 Escherichia coli, 20/26 Klebsiella pneumoniae and 8/15 Enterobacter cloacae). The remaining (5 Salmonella Enteritidis, 3 Morganella morganii 1 Proteus mirabilis and 1 Leclercia adecarboxylata) were ESBL negative. CTX-M-1 group enzymes were highly prevalent (89.6%) among ESBLs; the remaining ones being SHV. One E. coli produced an OXA-181 carbapenemase, which is the first CPE described in Mali. The analysis of ESBL-E relatedness suggested a high rate of cross transmission between patients. In conclusion, even if CPE are still rare for the moment, the high rate of ESBL-BSI and frequent cross transmission probably impose a high medical and economic burden to Malian hospitals.
International Journal of Mycobacteriology, 2016
Journal of AIDS & Clinical Research, 2016
Background: The announcement of HIV-positive status is a critical moment of psycho-social destabi... more Background: The announcement of HIV-positive status is a critical moment of psycho-social destabilization that can induce changes in the behavior of an individual such a beginning or increased tobacco consumption. Objective: The objective was to study the relationship between the HIV positive status announcement and smoking behavior among people living with human immunodeficiency virus (HIV) in Bamako after the discovering their status. Methods: We did a descriptive cross-sectional study over six months from January to June 2012. Data were collected by interviewing HIV infected patients in three health care centers, departments of pulmonary diseases, department of infectious and tropical diseases and the largest HIV clinic in Mali (CESAC of Bamako). All participants have signed an informed consent before the interview. Data were analyzed using Epi-Info version 7.1.5.2 software. Results: A total of 301 HIV-infected people were included, 24% patients were current smokers 6.3% former smokers and 69.7% non-smokers. Smokers were male in majority with 93.2%. After their HIV infection status announcement, 64.9% have increased their tobacco consumption while 10.8% have decreased their consumption. Majority of patients have a good knowledge of the health risks of smoking. Of those who continue to smoke, 83.8% reported that they tried and fail to stop smoking at least one time. The main reason of their cessation was the effect on their health. And the main reason for the failure was the constant thinking of the disease. Conclusion: The announcement of the HIV positivity status must be accompanied by psychosocial support helping to overcome the emotion and stress and a smoking cessation program must be added to HIV screening program.
Pan African Medical Journal, 2016
La maladie de Basedow est une affection auto immune associant une thyrotoxicose Ă des manifestati... more La maladie de Basedow est une affection auto immune associant une thyrotoxicose Ă des manifestations de frĂ©quence variable comme le goitre, l'ophtalmopathie et le myxoedème prĂ©tibial. Son diagnostic est souvent facile, tandis que sa prise en charge demeure encore difficile. L'instauration d'un traitement mĂ©dical simple expose Ă un risque de rĂ©cidive. Au SĂ©nĂ©gal et en Afrique Sub-saharienne peu d'Ă©tudes ont portĂ© sur la maladie de Basedow. L'objectif de l'Ă©tude Ă©tait de dĂ©crire les aspects Ă©pidĂ©miologique, clinique, thĂ©rapeutique et Ă©volutif de la maladie de Basedow en milieu hospitalier Ă Dakar. Il s'agissait d'une Ă©tude rĂ©trospective menĂ©e du 1er janvier 2010 au 31 dĂ©cembre 2013 dans le service de MĂ©decine Interne du centre hospitalier universitaire Aristide Le Dantec. Durant la pĂ©riode, 108 patients suivis en consultation externe pour maladie de Basedow, ont Ă©tĂ© inclus sur un total de 834 patients suivis en consultation externe. le diagnostic a Ă©tĂ© retenu devant les signes cliniques, biologiques et immunologiques. Cent huit patients, atteints de maladie de Basedow ont Ă©tĂ© inclus sur un total de 834 consultations. Le sex ratio Ă©tait de 7,3 et la moyenne d'Ă¢ge de 34,6 ans. Les principaux motifs de consultation Ă©taient : les palpitations et l'amaigrissement dans respectivement 46,3% et 39,8% des cas. Le syndrome de thyrotoxicose Ă©tait prĂ©sent chez 93,5% des patients, un goitre Ă©tait notĂ© chez 87% des patients et une exophtalmie chez 78,7% des patients. La principale complication Ă©tait Ă type de cardiothyrĂ©ose retrouvĂ©e chez 11,1% des patients. Tous les patients ont eu un traitement par antithyroĂ¯diens de synthèse. L'Ă©volution a Ă©tĂ© favorable dans 19,4% des cas. Une rĂ©cidive Ă Ă©tĂ© notĂ©e dans 57% des cas et dans 23,1% des cas les patients ont Ă©tĂ© perdus de vue. La maladie de Basedow est la cause de la plus frĂ©quente d'hyperthyroĂ¯die. Le tableau est dominĂ© par les manifestations cliniques liĂ©es Ă l'hyper mĂ©tabolisme de l'organisme. Dans cette Ă©tude, il apparait que la thyroĂ¯dectomie n'est pas de première intention si l'on connait le nombre Ă©levĂ© de rĂ©cidive après le traitement mĂ©dical.
IEEE Photonics Technology Letters, 2016
We report the fabrication of an ultra-high-Q monolithic whispering gallery-mode resonator using a... more We report the fabrication of an ultra-high-Q monolithic whispering gallery-mode resonator using a lithium fluoride crystal, with a quality factor above 10 8 at 1550 nm. We show that when pumped above a certain threshold, we can excite single Stokes Brillouin lasing in this resonator. We thereby demonstrate Brillouin lasing in a monofluoride crystal for the very first time, to the best of our knowledge. We provide a detailed theoretical investigation of Brillouin scattering in this resonator, using a time-domain model which tracks the dynamics of the Stokes and pump waves. We also perform a stability analysis which enables us to analytically determine the threshold pump power. We expect such crystalline Brillouin lasers to find potential applications for ultra-pure microwave and multiwavelength generation, as well as for compact sensors.
PLOS Neglected Tropical Diseases, 2016
Background Mycobacterium africanum, made up of lineages 5 and 6 within the Mycobacterium tubercul... more Background Mycobacterium africanum, made up of lineages 5 and 6 within the Mycobacterium tuberculosis complex (MTC), causes up to half of all tuberculosis cases in West Africa, but is rarely found outside of this region. The reasons for this geographical restriction remain unknown. Possible reasons include a geographically restricted animal reservoir, a unique preference for hosts of West African ethnicity, and an inability to compete with other lineages outside of West Africa. These latter two hypotheses could be caused by loss of fitness or altered interactions with the host immune system. Methodology/Principal Findings We sequenced 92 MTC clinical isolates from Mali, including two lineage 5 and 24 lineage 6 strains. Our genome sequencing assembly, alignment, phylogeny and average nucleotide identity analyses enabled us to identify features that typify lineages 5 and 6 and made clear that these lineages do not constitute a distinct species within the MTC. We found that in Mali, lineage 6 and lineage 4 strains have similar levels of diversity and evolve drug resistance through similar mechanisms. In the process, we identified a putative novel streptomycin resistance mutation. In addition, we found evidence of person-to-person transmission of lineage 6 isolates and showed that lineage 6 is not enriched for mutations in virulence-associated genes.
PLOS ONE, 2015
Background There are very limited data on children with pneumonia in Mali. The objective was to a... more Background There are very limited data on children with pneumonia in Mali. The objective was to assess the etiology and factors associated with community-acquired pneumonia in hospitalized children <5 years of age in Mali. Methods A prospective hospital-based case-control study was implemented in the Pediatric department of Gabriel Touré University Hospital at Bamako, Mali, between July 2011-December 2012. Cases were children with radiologically-confirmed pneumonia; Controls were hospitalized children without respiratory features, matched for age and period. Respiratory specimens, were collected to identify 19 viruses and 5 bacteria. Whole blood was collected from cases only. Factors associated with pneumonia were assessed by multivariate logistic regression. Results Overall, 118 cases and 98 controls were analyzed; 44.1% were female, median age was 11 months. Among pneumonia cases, 30.5% were hypoxemic at admission, mortality was 4.2%. Pneumonia cases differed from the controls regarding clinical signs and symptoms but not in terms of past medical history. Multivariate analysis of nasal swab findings disclosed that S. pneumoniae (adjusted odds ratio [aOR] = 3.4, 95% confidence interval [95%
Physical review letters, Jan 6, 2015
The dynamics of water in polyethylene oxide (PEO)/LiCl solution has been studied with quasielasti... more The dynamics of water in polyethylene oxide (PEO)/LiCl solution has been studied with quasielastic neutron scattering experiments and molecular dynamics (MD) simulations. Two different time scales of water diffusion representing interfacial water and bulk water dynamics have been identified. The measured diffusion coefficient of interfacial water remained 5-10 times smaller than that of bulk water, but both were slowed by approximately 50% in the presence of Li^{+}. Detailed analysis of MD trajectories suggests that Li^{+} is favorably found at the surface of the hydration layer, and the probability to find the caged Li^{+} configuration formed by the PEO is lower than for the noncaged Li^{+}-PEO configuration. In both configurations, however, the slowing down of water molecules is driven by reorienting water molecules and creating water-Li^{+} hydration complexes. Performing the MD simulation with different ions (Na^{+} and K^{+}) revealed that smaller ionic radius of the ions is a...
Applied Optics, 2015
We report a joint theoretical and experimental investigation of the parametric seeding of a prima... more We report a joint theoretical and experimental investigation of the parametric seeding of a primary Kerr optical frequency comb. Electro-optic modulation sidebands matching multiple free-spectral ranges of an ultrahigh-Q millimeter-size magnesium fluoride disk resonator are used as seed signals. These seed signals interact through four-wave mixing with the spectral components of a stable primary comb and give rise to complex spectro-temporal patterns. We show that the new frequency combs feature multiscale frequency spacing, with major frequency gaps in the order of a few hundred gigahertz, and minor frequency spacing in the order of a few tens of gigahertz. The experimental results are in agreement with numerical simulations using the Lugiato-Lefever equation. We expect such versatile and coherent optical frequency combs to have potential applications in optical communications systems where frequency management assigns predefined spectral windows at the emitter stage.
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Papers by souleymane diallo