La société sénégalaise et les enfants de la rue : approche socio-anthropologique des dynamiques d'exclusion et de survie : étude de cas à Dakar

Résumé : La société sénégalaise traverse une crise profonde qui touche tous les secteurs de la vie. Cette crise à la fois structurelle et conjoncturelle crée à son tour une sorte de société de la crise qui touche les populations les plus vulnérables. Le phénomène des enfants de la rue est l'expression parfaite de cette société de la crise. Le rythme dans lequel il se développe est la traduction de la dynamique d'exclusion qui sévit en milieu urbain sénégalais en général et dans la région de Dakar en particulier. Dans cette région, l'urbanisation s'est accompagnée de la montée des inégalités qui placent la société dans une sorte de dualisation entre centre et périphérie. A la ville de Dakar qui s'est constituée selon les normes de la planification urbaine, s'oppose les principales banlieues de Pikine, Guédiawaye et Rufisque qui offrent le visage de marges sociales urbaines. D'une certaine manière, la montée des inégalités remet en cause les politiques sociales, de la bonne gouvernance et de la redistribution des richesses. Ces banlieues constituent les principaux milieux d'accueil de la masse de migrants ruraux qui fuient la misère des villages. D'une part, l'hétérogénéité sociale de ces banlieues ne favorise pas l'émergence d'une conscience collective fondée sur l'appartenance à un fonds historique commun. Par contre, elle renforce l'anonymat et l'indifférence propres à la ville. D'autre part, les difficultés économiques et la précarité des conditions de vie conjuguées à l'explosion démographique et ses conséquences affaiblissent les systèmes de solidarité entraînant ainsi la montée de l'individualisme et la philosophie du chacun pour soi. Ce qui met en cause l'éducation des enfants qui devient difficile pour les parents d'assumer. En outre, la place importante accordée à l'imaginaire social dans la société sénégalaise explique le recours aux forces surnaturelles par l'intercession des marabouts, sorciers, devins, etc. D'autre part, la place accordée aux offrandes et aux sacrifices de même que le "besoin de donner" alimente et pérennise la pratique de la mendicité en général et celle des enfants en particulier. En outre, l'instrumentalisation de la mendicité par certains marabouts qui se traduit par une sorte de "business talibé" ou de "marché de l'aumône", rapproche les enfants de l'univers de là rue qui devient pour eux une sorte d'échappatoire face aux conditions de vie que leur imposent ces marabouts. Ainsi, pour eux, la rue remplit une fonction de socialisation. En effet, dans cet univers social, les enfants se forgent une personnalité, développent des compétences et des activités qui leur permettent de survivre, créent des repères et des codes collectifs qui leur permettent de mener une existence que la société assimile strictement à la déviance. Mots clé : crise, école, éducation, enfants de la rue, exclusion, inégalités, migration, pauvreté, socialisation, stratégies de survie, uibanisation.

Geographical and temporal body size variation in a reptile: roles of sex, ecology, phylogeny and ecology structured in phylogeny.

Geographical body size variation has long interested evolutionary biologists, and a range of mechanisms have been proposed to explain the observed patterns. It is considered to be more puzzling in ectotherms than in endotherms, and integrative approaches are necessary for testing non-exclusive alternative mechanisms. Using lacertid lizards as a model, we adopted an integrative approach, testing different hypotheses for both sexes while incorporating temporal, spatial, and phylogenetic autocorrelation at the individual level. We used data on the Spanish Sand Racer species group from a field survey to disentangle different sources of body size variation through environmental and individual genetic data, while accounting for temporal and spatial autocorrelation. A variation partitioning method was applied to separate independent and shared components of ecology and phylogeny, and estimated their significance. Then, we fed-back our models by controlling for relevant independent components. The pattern was consistent with the geographical Bergmann's cline and the experimental temperature-size rule: adults were larger at lower temperatures (and/or higher elevations). This result was confirmed with additional multi-year independent data-set derived from the literature. Variation partitioning showed no sex differences in phylogenetic inertia but showed sex differences in the independent component of ecology; primarily due to growth differences. Interestingly, only after controlling for independent components did primary productivity also emerge as an important predictor explaining size variation in both sexes. This study highlights the importance of integrating individual-based genetic information, relevant ecological parameters, and temporal and spatial autocorrelation in sex-specific models to detect potentially important hidden effects. Our individual-based approach devoted to extract and control for independent components was useful to reveal hidden effects linked with alternative non-exclusive hypothesis, such as those of primary productivity. Also, including measurement date allowed disentangling and controlling for short-term temporal autocorrelation reflecting sex-specific growth plasticity.

Comparative testing of a miniature diffusion size classifier to assess airborne ultrafine particles under field conditions

Miniature diffusion size classifiers (miniDiSC) are novel handheld devices to measure ultrafine particles (UFP). UFP have been linked to the development of cardiovascular and pulmonary diseases; thus, detection and quantification of these particles are important for evaluating their potential health hazards. As part of the UFP exposure assessments of highwaymaintenance workers in western Switzerland, we compared a miniDiSC with a portable condensation particle counter (P-TRAK). In addition, we performed stationary measurements with a miniDiSC and a scanning mobility particle sizer (SMPS) at a site immediately adjacent to a highway. Measurements with miniDiSC and P-TRAK correlated well (correlation of r = 0.84) but average particle numbers of the miniDiSC were 30%âeuro"60% higher. This difference was significantly increased for mean particle diameters below 40 nm. The correlation between theminiDiSC and the SMPSduring stationary measurements was very high (r = 0.98) although particle numbers from the miniDiSC were 30% lower. Differences between the three devices were attributed to the different cutoff diameters for detection. Correction for this size dependent effect led to very similar results across all counters.We did not observe any significant influence of other particle characteristics. Our results suggest that the miniDiSC provides accurate particle number concentrations and geometric mean diameters at traffic-influenced sites, making it a useful tool for personal exposure assessment in such settings.

Sudden weather deterioration but not brood size affects baseline corticosterone levels in nestling Alpine swifts.

While evidence is accumulating that stress-induced glucocorticoid responses help organisms to quickly adjust their physiology and behaviour to life-threatening environmental perturbations, the function and the ecological factors inducing variation in baseline glucocorticoid levels remain poorly understood. In this study we investigated the effects of brood size by experimentally manipulating the number of nestlings per brood and the effect of weather condition on baseline corticosterone levels of nestling Alpine swifts (Apus melba). We also examined the potential negative consequences of an elevation of baseline corticosterone on nestling immunity by correlating corticosterone levels with ectoparasite intensity and the antibody production towards a vaccine. Although nestlings reared in enlarged broods were in poorer condition than nestlings reared in reduced broods, they showed similar baseline corticosterone levels. In contrast, nestling baseline corticosterone levels were higher immediately after cold and rainy episodes with strong winds. Neither nestling infestation rate by ectoparastic flies nor nestling antibody production against a vaccine was correlated with baseline corticosterone levels. Thus, our results suggest that altricial Alpine swift nestlings can quickly modulate baseline corticosterone levels in response to unpredictable variations in meteorological perturbation but not to brood size which may be associated with the degree of sibling competition. Apparently, short-term elevations of baseline corticosterone have no negative effects on nestling immunocompetence.

Quantitative monitoring of tamoxifen in human plasma extended to 40 metabolites using liquid-chromatography high-resolution mass spectrometry: new investigation capabilities for clinical pharmacology.

Liquid-chromatography (LC) high-resolution (HR) mass spectrometry (MS) analysis can record HR full scans, a technique of detection that shows comparable selectivity and sensitivity to ion transitions (SRM) performed with triple-quadrupole (TQ)-MS but that allows de facto determination of "all" ions including drug metabolites. This could be of potential utility in in vivo drug metabolism and pharmacovigilance studies in order to have a more comprehensive insight in drug biotransformation profile differences in patients. This simultaneous quantitative and qualitative (Quan/Qual) approach has been tested with 20 patients chronically treated with tamoxifen (TAM). The absolute quantification of TAM and three metabolites in plasma was realized using HR- and TQ-MS and compared. The same LC-HR-MS analysis allowed the identification and relative quantification of 37 additional TAM metabolites. A number of new metabolites were detected in patients' plasma including metabolites identified as didemethyl-trihydroxy-TAM-glucoside and didemethyl-tetrahydroxy-TAM-glucoside conjugates corresponding to TAM with six and seven biotransformation steps, respectively. Multivariate analysis allowed relevant patterns of metabolites and ratios to be associated with TAM administration and CYP2D6 genotype. Two hydroxylated metabolites, α-OH-TAM and 4'-OH-TAM, were newly identified as putative CYP2D6 substrates. The relative quantification was precise (<20 %), and the semiquantitative estimation suggests that metabolite levels are non-negligible. Metabolites could play an important role in drug toxicity, but their impact on drug-related side effects has been partially neglected due to the tremendous effort needed with previous MS technologies. Using present HR-MS, this situation should evolve with the straightforward determination of drug metabolites, enlarging the possibilities in studying inter- and intra-patients drug metabolism variability and related effects.

Length of activity season drives geographic variation in body size of a widely distributed lizard

Understanding the factors that drive geographic variation in life history is an important challenge in evolutionary ecology. Here, we analyze what predicts geographic variation in life-history traits of the common lizard, Zootoca vivipara, which has the globally largest distribution range of all terrestrial reptile species. Variation in body size was predicted by differences in the length of activity season, while we found no effects of environmental temperature per se. Females experiencing relatively short activity season mature at a larger size and remain larger on average than females in populations with relatively long activity seasons. Interpopulation variation in fecundity was largely explained by mean body size of females and reproductive mode, with viviparous populations having larger clutch size than oviparous populations. Finally, body size-fecundity relationship differs between viviparous and oviparous populations, with relatively lower reproductive investment for a given body size in oviparous populations. While the phylogenetic signal was weak overall, the patterns of variation showed spatial effects, perhaps reflecting genetic divergence or geographic variation in additional biotic and abiotic factors. Our findings emphasize that time constraints imposed by the environment rather than ambient temperature play a major role in shaping life histories in the common lizard. This might be attributed to the fact that lizards can attain their preferred body temperature via behavioral thermoregulation across different thermal environments. Length of activity season, defining the maximum time available for lizards to maintain optimal performance, is thus the main environmental factor constraining growth rate and annual rates of mortality. Our results suggest that this factor may partly explain variation in the extent to which different taxa follow ecogeographic rules.

Sample size and statistical power in the hierarchical analysis of variance: applications in morphometry of the nervous system.

Analysis of variance is commonly used in morphometry in order to ascertain differences in parameters between several populations. Failure to detect significant differences between populations (type II error) may be due to suboptimal sampling and lead to erroneous conclusions; the concept of statistical power allows one to avoid such failures by means of an adequate sampling. Several examples are given in the morphometry of the nervous system, showing the use of the power of a hierarchical analysis of variance test for the choice of appropriate sample and subsample sizes. In the first case chosen, neuronal densities in the human visual cortex, we find the number of observations to be of little effect. For dendritic spine densities in the visual cortex of mice and humans, the effect is somewhat larger. A substantial effect is shown in our last example, dendritic segmental lengths in monkey lateral geniculate nucleus. It is in the nature of the hierarchical model that sample size is always more important than subsample size. The relative weight to be attributed to subsample size thus depends on the relative magnitude of the between observations variance compared to the between individuals variance.

Quantification of glucuronidated and sulfated steroids in human urine by ultra-high pressure liquid chromatography quadrupole time-of-flight mass spectrometry.

The urinary steroid profile is constituted by anabolic androgenic steroids, including testosterone and its relatives, that are extensively metabolized into phase II sulfated or glucuronidated steroids. The use of liquid chromatography coupled to mass spectrometry (LC-MS) is an issue for the direct analysis of conjugated steroids, which can be used as urinary markers of exogenous steroid administration in doping analysis, without hydrolysis of the conjugated moiety. In this study, a sensitive and selective ultra high-pressure liquid chromatography coupled to quadrupole time-of-flight mass spectrometer (UHPLC-QTOF-MS) method was developed to quantify major urinary metabolites simultaneously after testosterone intake. The sample preparation of the urine (1 mL) was performed by solid-phase extraction on Oasis HLB sorbent using a 96-well plate format. The conjugated steroids were analyzed by UHPLC-QTOF-MS(E) with a single-gradient elution of 36 min (including re-equilibration time) in the negative electrospray ionization mode. MS(E) analysis involved parallel alternating acquisitions of both low- and high-collision energy functions. The method was validated and applied to samples collected from a clinical study performed with a group of healthy human volunteers who had taken testosterone, which were compared with samples from a placebo group. Quantitative results were also compared to GC-MS and LC-MS/MS measurements, and the correlations between data were found appropriate. The acquisition of full mass spectra over the entire mass range with QTOF mass analyzers gives promise of the opportunity to extend the steroid profile to a higher number of conjugated steroids.

Le peuple élu et les autres. L'Ancien Testament entre exclusion et ouverture

La conviction d'être le peuple élu s'enracine au coeur de la foi d'Israël. Mais elle justifia aussi par réaction tous les antisémitismes. La Bible, pourtant, ne nous fait pas entendre qu'un seul discours sur l'élection. A trop vite tirer à soi tel passage, on en vient à travestir dangereusement son message. En réalité la critique des dérives intégristes auxquelles peut donner et a donné lieu le thème de l'élection d'Israël est le fait de l'Ancien Testament lui-même. Il est vrai que dans les temps d'oppresion et de déportation la conscience d'être le peuple de Dieu a permis à Israël de fortifier son espérance et d'assurer son identité. Et ce fut là, notamment, le grand dessein auquel se consacrèrent les auteurs successsifs du Deutéronome, à l'époque de la domination assyrienne, puis de l'exil babylonien. Mais il est tout aussi vrai qu'à chaque fois aussi se sont levés des hommes avertis, dans la foulée des propnètes de jadis, pour mettre en garde contre la tentation du nombrilisme voire de l'exclusivisme ravageur. L'histoire d'Abraham réécrite au retour de l'exil, en est l'exemple le plus impressionnant, qui souligne combien Dieu n'a cessé d'élargir à tous les pepes son électon et sa bénédiction.

Determination of plasma levels of citalopram and its demethylated and deaminated metabolites by gas chromatography and gas chromatography-mass spectrometry.

Sensitive and specific methods based on gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) for the determination of levels of citalopram, desmethylcitalopram and didesmethylcitalopram in the plasma of patients treated with citalopram are presented, as well as a GC-MS procedure for the assay of the citalopram propionic acid derivative. After addition of a separate internal standard for each drug, liquid-solvent extraction is used to separate the basic compounds from the acid compounds. The demethylated amines are derivatized with trifluoroacetic anhydride, and the acid metabolite with methyl iodide. GC-MS is performed in the electron impact mode, as mass spectrometry by the (positive-ion) chemical ionization mode (methane and ammonia) appeared to be unsuitable. The limits of quantification were 1 ng/ml for citalopram and desmethylcitalopram and 2 ng/ml for the other metabolites. The correlation coefficients for the calibration curves (range 10-500 ng/ml) were &gt; or = 0.999 for all compounds, whether determined by GC or GC-MS.