63 research outputs found
Neurals Networks for Projecting Named Entities from English to Ewondo
Named entity recognition is an important task in natural language processing.
It is very well studied for rich language, but still under explored for
low-resource languages. The main reason is that the existing techniques
required a lot of annotated data to reach good performance. Recently, a new
distributional representation of words has been proposed to project named
entities from a rich language to a low-resource one. This representation has
been coupled to a neural network in order to project named entities from
English to Ewondo, a Bantu language spoken in Cameroon. Although the proposed
method reached appreciable results, the size of the used neural network was too
large compared to the size of the dataset. Furthermore the impact of the model
parameters has not been studied. In this paper, we show experimentally that the
same results can be obtained using a smaller neural network. We also emphasize
the parameters that are highly correlated to the network performance. This work
is a step forward to build a reliable and robust network architecture for named
entity projection in low resource languages
Tritiated thymidine internalization in zebrafish embryo and larvae: how do microdosimetry and experimental processes complete each other?
Natural aquatic populations are at risk of an exposure to radionuclides emitting different types of radiation. Exposure of an organism to radionuclides leads to different effects that depend on different factors such as the radiation type, its cellular repartition, the activity, and the exposure duration leading to an absorbed dose. The subcellular characterization of the radionuclide distribution and its associated absorbed dose are then crucial to characterize the underlying mechanisms associated to each induced effect. Toxicity of beta radiations on aquatic organisms is not well known. Several studies showed that in the case of tritiated water, its internalization in zebrafish in its early development stages (4 days post fecundation) increases linearly with the tritium activity in the water. Several deleterious effects arising from an exposure to tritium include modified gene expression, increase in DNA damage and gamma-H2AX foci, leading to phenotypes as well changes in the swimming behavior,as and muscle alterations. This study focuses on tritiated thymidine, a form of organic tritium. , as aA study on the mussel has showed already shown that tritiated glycine induced a stronger toxicity than tritiated water. Our study’s results could also lead to a better understanding of the effects observed after an exposure to tritiated water . A focus was also made on micro- and nano-dosimetry simulations, as multiple studies showed that it leads to a better understanding the effects of the radiation repartition of the radiation, and the damages that could arise from it. In order to study tritiated thymidine the toxicity of tritiated thymidine on zebrafish in its early development stages, its internalization and cellular repartition needed to be studiedcharacterized. Zebrafish embryos (3.5 hpf) were exposed to tritiated thymidine at different activity concentrations (2.4x103 to 5.95x105 Bq/mL) and the tritium internalization was measured in zebrafish embryos, larvae and their DNA after 1 and 4 days of exposure. Microdosimetry obtained by Monte Carlo simulations was also used in order to characterize represent the cellular repartition of the energy deposits. Experimental results showed that tritium was mainly internalized in its organic form, and that the internalization increased exponentially with the external activity before reaching a saturating point at around 1200 and 600 µGy/h when embryos and larvae were incubated at around 3x105 Bq/mL for embryos and larvae, respectively (log-logistic increase). Results also showeshow d that in presence of at 3.2x103 and 3.7x104 Bq/mL, tritium levels in DNA were of at 0.2 and 1.2 Bq/µg of DNA (???) respectively. Those levels were not statistically different after 24 and 96 hours of exposure. Microdosimetry simulations showed that the mean imparted energy deposited by the tritium decay increased linearly with the cell radius. The simulation results also showed that smaller cells were more at risk of being the target of small energy deposits. Those energy deposits also being closer to each other, it means the cells are could be at a higher biological risk. Deleterious effects as development defects, swimming behavior perturbations, DNA damage inductions, or gene expression modifications after exposure to 30 and 150 µGy/h are under investigation, and DNA damage will be linked to nano-dosimetry simulations giving theoretical information about the DNA damage that could arise from our this type of exposures
Tritiated thymidine internalization in zebrafish early life stages: joint use of experimental procedures and microdosimetry
Tritium is found in the environment under three forms: free in the water, gaseous, and bound to organic matter. Once internalized in living organisms, it can be found in two forms: tissue free water tritium (TFWT) and organically bound tritium (OBT). This study aims to better understand OBT internalization in living organisms and to show the complementarity between experimental procedures and microdosimetry simulations that have often been used to obtain more information on imparted energy to cell nuclei. To do so, tritiated thymidine, an organic form of tritium, was chosen and zebrafish embryos [3.5 h post fertilization (hpf)] were exposed to a range of activity concentrations (2.21 × 103 to 5.95 × 105 Bq/mL). First, individual zebrafish embryos were sampled after different exposure times (1 to 96 h) to qualify the internalization kinetics. Then, the barrier role of the chorion was assessed after 2 days of exposure. Lastly, individual zebrafish embryos were sampled after 1 and 4 days of exposure to measure the internalization in the whole fish and its DNA, but also to highlight a possible link between the internal dose rate and the external activity concentration. Microdosimetry simulations were also made to quantify the imparted energy that could occur in the zebrafish cells after exposure to tritium. Results showed that when bound to thymidine, tritium rapidly incorporates in zebrafish early life stages, with the internalization being almost complete after 24 h. Results also showed that while the chorion acted as a barrier to prevent thymidine from entering the embryos, significant levels could still be measured in the whole organisms as well as in DNA. This study also highlighted that when the external activity concentration increased, the internal dose rate increased as well, following a sigmoidal trend. Microdosimetry simulations highlighted that the size and shape of the cell matters, and that the smallest cells seem to be at the greater risk, with only low-energy electrons inducing energy depositions. A linear fit was also found between the mean energy deposited and the logarithm of the radius of the cell, thus showing that the quantity of deposited energy is proportional to the radius of the cell. While this study highlighted important internalization pattern, it will also be used as the starting point of a study focusing on the toxic effects of tritiated thymidine on zebrafish in its early life stages
Caracterisation phenotypique des populations locales de poulets (Gallus gallus domesticus) au Togo
L’étude a été conduite du 19 Août au 27 septembre 2013 dans cinq zones agro-écologiques du Togo. L’objectif était de caractériser les popula-tions locales de poules (Gallus gallus domesticus) en se basant sur les différents phénotypes. Pour ce faire, un échantillon de 750 poules adultes dont 600 poules et 150 coqs issus de 30 cantons a été constitué. Chaque poule a été décrite par observation directe puis le poids et les mensura-tions corporelles ont été enregistrés. Une grande variabilité phénotypique dans la coloration et le type du plumage des poules a été observée. Les couleurs de plumage les plus rencontrées sont : le perdrix doré (16,7%), le caillouté (11,3%) chez la poule, le mille – fleur (28%), le rouge à queue noir (22%) et le blanc chez le coq. Trois types de plumage ont été observés: le lisse (96,3%), le soyeux (2,8%) et le frisé (0,9%) ont été décrits. L’emplument normal est très représenté (82%), mais d’autres empluments tels que le huppé (41%), le cou nu (0,83%), les tarses emplumés (0,33%) et les « barbe avec favoris » (0,22%) sont rencontrés. Les tarses des poules sont de coloration blanche (34%), jaunes (30%), gris (26,83 %) et noires (9,17%). La coloration des yeux des poules est surtout orangée (92,279%). Les crêtes de type simple sont dominantes (95,87%) tandis que le phénotype « polydactyle » est rencontré à une fréquence de 2,8%. Un dimorphisme sexuel pour le poids vif a été observé car les poids moyens sont de 1088,62g ± 244,26 et 1540,81g ±399,74 respectivement chez les poules et les coqs. D’une manière générale, les poules de la Savane Sèche présentent un format et un poids plus élevés que ceux des autres zones. Le format et le poids des poules diminuent suivant un gradient allant du nord au sud du pays.Mots clés : Caractérisation phénotypique, Poules locale, Zones agro-écologiques, Togo
Etude comparee de l’efficacite de trois methodes de prévention des maladies des pintadeaux au nord du Togo
L’élevage de la pintade se heurte à de nombreuses contraintes touchant principalement la santé des pintadeaux. Des mortalités des pintadeaux et des pintades sont fréquemment enregistrées dans les élevages. Afin de proposer une ou des méthodes de lutte efficaces, cette étude conduite au nord Togo a eu comme objectif d’apprécier le taux de mortalité des pintadeaux suivant trois méthodes de prévention des maladies des pintadeaux. L’étude a été conduite en station au Centre de Recherche Agronomique de la Savane Sèche (CRASS) à Dapaong. Le lot bénéficiant d’un traitement prophylactique à base des produits vétérinaires a enregistré le plus faible taux de mortalité de (19,23%) contre 30,76 % pour le lot 2 et 38,46 % pour le lot 3, suivis en se basant sur le savoir-faire local. Aucune différence significative (p = 0,3099) n’a été observée entre ces lots. Les pintadeaux du lot témoin ne bénéficiant d’aucun traitement sont tous morts avant la fin de l’expérimentation. Au vu de ces résultats, il est important de signaler que certaines connaissances locales sont prometteuses en matière de lutte contre les maladies despintadeaux et méritent une amélioration avant leur recommandation.Mots clés : Pintadeaux, maladies, Togo. Comparative survey of the efficiency of three different prophylactic programs tested on guinea poults breeding in northern TogoGuinea-fowl breeding encounters many constraints concerning mainly health of the guinea poults. Deaths of guinea-fowl and guinea poults are frequently reported from the farms. In order to present efficient fighting methods, the aim of this survey held in northern Togo was to evaluate death rates of guinea poults according to three different prophylactic programs. The survey took place at Centre de Recherche Agronomique dela Savane Sèche (CRASS) in Dapaong. The group which benefited from a prophylactic treatment of veterinarian products had a lower death rate (19.23%) compared to the other ones (30.76% and 38.46%) who were treated in the traditional local ways. No significant difference has been observed between these groups (p = 0.3099). The guinea poults of the control group, who were not undergoing any treatment all died before theend of the experiment. According to those results, it is important to report that some local/traditional uses may lately be used against guinea poults diseases, but will need to go through increase before they are prescribed.Keywords: Guinea-fowl, diseases, Togo
Internalisation du tritium sous forme organique chez les embryons et larves de poisson zèbre.
Les populations naturelles d'organismes aquatiques sont exposées à des radionucléides émetteurs de différents types de radionucléides (α, β, γ) [1]. Ces expositions peuvent mener à l'apparition d'effets délétères qui dépendent de plusieurs facteurs tels que le type de rayonnement, la dose absorbée, le temps d'exposition et la répartition subcellulaire du radionucléide dans l'organisme. La caractérisation à l'échelle subcellulaire de la distribution d'un radionucléide et la dose associée est donc cruciale pour déterminer les mécanismes associés aux effets induits [2]. Une étude a mis en avant qu'après une exposition au tritium libre, l'internalisation chez les embryons et larves de poisson zèbre augmente linéairement avec l'activité présente dans le milieu [1]. Deux autres études ont mis en avant que l'exposition du poisson zèbre au tritium libre pendant son développement entraîne une modification de l'expression de certains gènes et une augmentation du taux de dommages à l'ADN menant à des altérations musculaires et à une modification du comportement natatoire des larves [3]. Cette étude se concentre sur le tritium sous forme organique, plus spécifiquement la thymidine tritiée. Afin d'étudier la toxicité de la thymidine tritiée sur le poisson zèbre à ses stades précoces de développement, l'internalisation du tritium et la répartition subcellulaire de ses dépôts d'énergie ont été étudiés. Des embryons de poisson zèbre ont été exposés à de la thymidine tritiée à différentes activités (de 2,4 à 595 kBq/mL) et l'internalisation du tritium a été mesurée dans les embryons et larves de poisson zèbre (1 et 4 jours post fertilisation). Des simulations de microdosimétrie ont également été réalisées en utilisant les calculs Monte Carlo sur Geant4-DNA afin de représenter la répartition cellulaire des dépôts d'énergie. Les résultats expérimentaux ont montré que le tritium était majoritairement internalisé sous forme organique, et que son internalisation augmentait exponentiellement avec l'activité externe jusqu'à atteindre un point de saturation à environ 250 kBq/mL chez les œufs et les larves, respectivement. Les simulations de microdosimétrie ont montré que l'énergie moyenne déposée par le tritium augmentait linéairement avec le rayon de la cellule. Les simulations ont également mis en avant que les cellules aux plus faibles rayons étaient plus à risque d'être la cible des électrons de faible énergie. Ces électrons réalisant des dépôts d'énergie plus proches les uns des autres, un plus grand risque biologique est également estimé dans le cas des cellules de plus faible rayon. Le développement, le comportement natatoire, l'intégrité de l'ADN et l'expression génique de certains gènes d'intérêt sont en cours d'étude chez les individus exposés à de la thymidine tritiée à des débits de dose de 8 et 40 kBq/mL pendant 1 à 4 jours
Effets sub-léthaux du tritium sous forme organique chez les embryons et larves de poisson zèbre.
Translational activation by the noncoding RNA DsrA involves alternative RNase III processing in the rpoS 5′-leader
The intricate regulation of the Escherichia coli rpoS gene, which encodes the stationary phase sigma-factor σS, includes translational activation by the noncoding RNA DsrA. We observed that the stability of rpoS mRNA, and concomitantly the concentration of σS, were significantly higher in an RNase III-deficient mutant. As no decay intermediates corresponding to the in vitro mapped RNase III cleavage site in the rpoS leader could be detected in vivo, the initial RNase III cleavage appears to be decisive for the observed rapid inactivation of rpoS mRNA. In contrast, we show that base-pairing of DsrA with the rpoS leader creates an alternative RNase III cleavage site within the rpoS/DsrA duplex. This study provides new insights into regulation by small regulatory RNAs in that the molecular function of DsrA not only facilitates ribosome loading on rpoS mRNA, but additionally involves an alternative processing of the target
Antiproliferative and palliative activity of flavonoids in colorectal cancer
Flavonoids are plant bioactive compounds of great interest in nutrition and pharmacology, due to their remarkable properties as antioxidant, anti-inflammatory, antibacterial, antifungal and antitumor drugs. More than 5000 different flavonoids exist in nature, with a huge structural diversity and a plethora of interesting pharmacological properties. In this work, five flavonoids were tested for their potential use as antitumor drugs against three CRC cell lines (HCT116, HT-29 and T84). These cell lines represent three different stages of this tumor, one of which is metastatic. Xanthohumol showed the best antitumor activity on the three cancer cell lines, even better than that of the clinical drug 5-fluorouracil (5-FU), although no synergistic effect was observed in the combination therapy with this drug. On the other hand, apigenin and luteolin displayed slightly lower antitumor activities on these cancer cell lines but showed a synergistic effect in combination with 5-FU in the case of HTC116, which is of potential clinical interest. Furthermore, a literature review highlighted that these flavonoids show very interesting palliative effects on clinical symptoms such as diarrhea, mucositis, neuropathic pain and others often associated with the chemotherapy treatment of CRC. Flavonoids could provide a double effect for the combination treatment, potentiating the antitumor effect of 5-FU, and simultaneously, preventing important side effects of 5-FU chemotherapy
Optimization of pre-inoculum, fermentation process parameters and precursor supplementation conditions to enhance apigenin production by a recombinant streptomyces albus strain
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