2,789 research outputs found
Between fetishism and survival : is the scientific article an academic commodity?
No full textThis article discusses the possible meanings of the intense prevailing concern in academic circles over the notion of research productivity, as reflected in an excess number of articles published in various scientific journals. The numerical accounting of articles published by researchers in scientific journals with renowned academic status serves to legitimize academics in their fields of work, in various ways. In this sense, we suggest that scientific articles take on aspects of merchandise-as-fetish, according to Marx's theory of use-value and exchange-value and Benjamin's exposure value. Meanwhile, the biological notions of selection and evolution are used as metaphorical elements in "bibliographic Darwinism". There are references as to the possibility many of the prevailing bibliometric concerns serve as instruments for econometric analysis, especially to orient and enhance cost-effectiveness analysis in research investments of various orders and types, from the point of view of their economic return
Optimisation of the Microwave-Assisted Ethanol Extraction of Saponins from Gac (Momordica cochinchinensis Spreng.) Seeds
No full textBACKGROUND: Gac (Momordica cochinchinensis Spreng.) seeds contain saponins that are reportedly medicinal. It was hypothesised that the extraction of saponins from powdered Gac seed kernels could be optimised using microwave-assisted extraction (MAE) with ethanol as the extraction solvent. The aim was to determine an appropriate ethanol concentration, ratio of solvent to seed powder and microwave power and time for extraction. Whether or not defatting the Gac seed powder had an impact on the extraction of saponins, was also determined. RESULTS: A four-fold higher total saponin content (TSC) was obtained in extracts from full-fat Gac seed kernel powder than from defatted powder (100 vs. 26 mg aescin equivalents (AE) per gram of Gac seeds). The optimal parameters for the extraction of saponins were a ratio of 30 mL of 100% absolute ethanol per g of full-fat Gac seed kernel powder with the microwave set at 360 W for three irradiation cycles of 10 s power ON and 15 s power OFF per cycle. CONCLUSIONS: Gac seed saponins could be efficiently extracted using MAE. Full-fat powder of the seed kernels is recommended to be used for a better yield of saponins. The optimised MAE conditions are recommended for the extraction of enriched saponins from Gac seeds for potential application in the nutraceutical and pharmaceutical industries
Journée d'étude - "Genre et excellence dans le monde académique"
No full textJeudi 5 mars 2015, De 9h à 13h, ULB - Salle Dupréel - Bâtiment S - 44, avenue Jeanne 1050 Bruxelles Journée d'étude organisée dans le cadre du cycle de conférences "Femmes et universités" Présentation : Le monde académique en Europe sous-utilise une part importante de son potentiel intellectuel et de sa capacité de recherche, à savoir celle des femmes. Des recherches récentes montrent que de nombreux mécanismes prévalant dans les pratiques de recrutement et de nomination des chercheurs sont d..
Journée d'étude - "Genre et excellence dans le monde académique"
No full textJeudi 5 mars 2015, De 9h à 13h, ULB - Salle Dupréel - Bâtiment S - 44, avenue Jeanne 1050 Bruxelles Journée d'étude organisée dans le cadre du cycle de conférences "Femmes et universités" Présentation : Le monde académique en Europe sous-utilise une part importante de son potentiel intellectuel et de sa capacité de recherche, à savoir celle des femmes. Des recherches récentes montrent que de nombreux mécanismes prévalant dans les pratiques de recrutement et de nomination des chercheurs sont d..
Optimisation of the microwave-assisted ethanol extraction of saponins from Gac (Momordica cochinchinensis Spreng.) seeds
No full textGac (Momordica cochinchinensis Spreng.) seeds contain saponins that are reportedly medicinal. It was hypothesised that the extraction of saponins from powdered Gac seed kernels could be optimised using microwave-assisted extraction (MAE) with ethanol as the extraction solvent. The aim was to determine an appropriate ethanol concentration, ratio of solvent to seed powder and microwave power and time for extraction. Whether or not defatting the Gac seed powder had an impact on the extraction of saponins, was also determined.A four-fold higher total saponin content (TSC) was obtained in extracts from full-fat Gac seed kernel powder than from defatted powder (100 vs. 26 mg aescin equivalents (AE) per gram of Gac seeds). The optimal parameters for the extraction of saponins were a ratio of 30 mL of 100% absolute ethanol per g of full-fat Gac seed kernel powder with the microwave set at 360 W for three irradiation cycles of 10 s power ON and 15 s power OFF per cycle. Gac seed saponins could be efficiently extracted using MAE. Full-fat powder of the seed kernels is recommended to be used for a better yield of saponins. The optimised MAE conditions are recommended for the extraction of enriched saponins from Gac seeds for potential application in the nutraceutical and pharmaceutical industries
Geminate latency in Djibouti Somali: A pilot study
No full textInternational audienceOur aim in this article is first to contribute to the documentation of the diatopic variation in the realization of Somali geminates, and second to determine whether Djibouti Somali exhibits geminate latency, on a par with Standard Somali (Barillot 2002, Barillot & Ségéral 2005). To this effect, we present the results of two production experiments that were conducted with one Djibouti Somali speaker. Section 1 examines the realization of the contrast /b, d, ɡ/ vs /bb, dd, ɡɡ/ in nouns in Djibouti Somali (Experiment 1-Nouns) in comparison with the previous experiment we conducted on Standard Somali (Bendjaballah & Le Gac 2021). Based on the results of this experiment, Section 2 addresses the question of geminate latency in Djibouti Somali. ‘Latent’ geminates are segments that are phonologically long but whose phonetic duration is short. We examine the acoustic realization of voiced singletons (/b, d, ɡ/), voiced geminates (/bb, dd, ɡɡ/) and voiceless geminates (/tt, kk/) in Djibouti Somali (Experiment 2-Verbs). Section 3 concludes the article, and argues in favour of an extension of geminate latency both in Standard Somali and in Djibouti Somali: geminate latency does not only concern the voiceless stops but also the voiced stops
Experimental impact of power re-optimization in a mesh network
No full textWe experimentally observe the signal-to-noise ratio (SNR) degradation of previously established services induced by loading new services in a network, and we mitigate this degradation by periodic power re-optimization via two different strategies: (1) a static strategy based on end-of-life parameters and (2) a dynamic strategy based on real-time monitoring to the current state of the network. We use a mesh network testbed of four nodes and five links with commercial equipment only. We observe up to 3.4 dB SNR degradation on the previously established services due to the loading of new services. Then we demonstrate an improvement of up to 3.2 dB in the network margin achieved by applying our proposed power re-optimization strategy
Treatment of inhibitory wastewaters using expanded-bed anaerobic GAC reactors
No full textThe expanded-bed anaerobic GAC reactor, operating with GAC replacement, was demonstrated to effectively treat wastewaters which contain toxic chemicals that resist biodegradation and inhibit the utilization of the biodegradable constituents of the wastewater.The objectives of the study were to investigate the effect of the GAC replacement rate on the process performance, evaluate the impact of the organic loading and hydraulic retention time (HRT) on the treatment efficiency, and to develop a predictive model for the process. A synthetic wastewater consisting of acetate, phenol and o-cresol, as model compounds of pollutants that exhibit different types of behavior in the anaerobic reactor with respect to biodegradability, adsorbability on GAC and inhibition, was used for the purposes of this study. GAC replacement rates of 25, 37.5, 50, 75, 100, and 150 g/d were employed in this study.The anaerobic GAC reactors were operated in a wide range of GAC mean residence times and very high organic removal efficiencies due to adsorption on GAC and biodegradation were observed at the different GAC mean residence times investigated in this study. Adsorption and biodegradation complemented each other as removal mechanism in this reactor with a dominance of biodegradation at high residence times and appreciable contributions from adsorption at low GAC residence times. A technique to measure the shear loss coefficients of the microbial populations present in the system was developed. The shear loss coefficients for the acetate and phenol utilizing organisms were found to differ appreciably. The findings of the study demonstrated the importance of biomass shear loss as a phenomenon that can impact the performance of the anaerobic GAC reactor significantly, particularly at low GAC mean residence times.A steady-state model that includes representations of the various interactions that occur within the anaerobic reactor such as adsorption and biodegradation was developed and tested against experimental data. The model incorporated the effects of inhibition of phenol degradation by o-cresol, biomass loss by shearing, the competition for adsorption between phenol and o-cresol, and the effect of GAC mean residence time on the adsorptive capacity of GAC. Using independently-determined adsorption parameters, the measured shear loss coefficients, and literature values for the kinetic parameters that describe acetate and phenol biodegradation, the developed model was used to predict the reactor's performance. The experimental data were in good agreement with the model predictions.Made available in DSpace on 2011-05-07T12:58:27Z (GMT). No. of bitstreams: 2
license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5)
9010966.pdf: 4885610 bytes, checksum: c6eb9cf0fec37439e0511db1a39767ab (MD5)
Previous issue date: 1989Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding ([email protected]) on 2011-05-07T14:48:29Z
Item is restricted indefinitely.Restriction data tranferred 2014-07-01T11:21:58-05:00
Original Data
Group with Access UIUC Users [automated]
Release Date: none
Reason: ETDs are only available to UIUC Users without author permissionETDs are only available to UIUC Users without author permissionU of I Onl
Etude d'un cache 2D adaptatif et predictif pour le traitement d'image
No full textLa necessite de definir des infrastructures materielles capables de supporter la grande diversite et complexite des algorithmes de traitement d'image, pour des taches telles que la vision, se fait toujours plus forte. Aussi nous proposons une hierachie memoire bidimensionnelle susceptible de compenser, pour une large classe d'applications, la latence de memoires de type SDRAM. En e#et, ces memoires deviennent un goulot d'etranglement lorsqu'y sont stockees des images sur lesquelles sont fait des acces aleatoires. Le cache 2D adaptatif et predictif (cache 2D-AP) propose repose sur une analyse statistique des coordonn ees des pixels utilises au cours du traitement. Cette analyse nous permet de determiner une taille optimale de la zone en cache et de predire les prochains acces a l'image. Comparativement a des caches standards comme ceux des TM32 ou PowerPC405, cette strategie ameliore la latence des acces memoire jusqu'a un facteur 6 et la taille du cache jusqu'a un facteur 40 pour de nombreuses applications. Ce travail illustre la possibilite d'utiliser les techniques du traitement du signal pour le controle des architectures complexes
Regulation of the Gac/Rsm pathway in "Pseudomonas fluorescens" CHA0
No full textSUMMARY :
Two-component systems are key mediators implicated in the response of numerous bacteria to a wide range of signals and stimuli. The two-component system comprised of the sensor kinase GacS and the response regulator GacA is broadly distributed among γ-proteobacteria bacteria and fulfils diverse functions such as regulation of carbon storage and expression of virulence. In Pseudomonas fluorescens, a soil bacterium which protects plants from root-pathogenic fungi and nematodes, the GacS/GacA two-component system has been shown to be essential for the production of secondary metabolites and exoenzymes required for the biocontrol activity of the bacterium. The regulatory cascade initiated by GacS/GacA consists of two translational repressor proteins, RsmA and RsmE, as well as three GacAcontrolled small regulatory RNAs RsmX, RsmY and RsmZ, which titrate RsmA and RsmE to allow the expression of biocontrol factors.
Genetic analysis revealed that two additional sensor kinases termed RetS and Lads were involved as negative and positive control elements, respectively, in the Gac/Rsm pathway in P. fluoresens CHAO. Furthermore, it could be proposed that RetS and Lads interact with GacS, thereby modulating the expression of antibiotic compounds and hydrogen cyanide, as well as the rpoS gene encoding the stress and stationary phase sigma factor σ. Temperature was found to be an important environmental cue that influences the Gac/Rsm network. Indeed, the production of antibiotic compounds and hydrogen cyanide was reduced at 35°C, by comparison with the production at 30°C. RetS was identified to be involved in this temperature control.
The small RNA RsmY was confirmed to be positively regulated by GacA and RsmA/RsmE. Two essential regions were identified in the rsmY promoter by mutational analysis, the upstream activating sequence (UAS) and the linker sequence. Although direct experimental evidence is still missing, several observations suggest that GacA may bind to the UAS, whereas the linker region would be recognized by intermediate RsmA/RsmEdependent repressors and/or activators. In conclusion, this work has revealed new elements contributing to the function of the signal transduction mechanisms in the Gac/Rsm pathway.
RESUME :
Les systèmes ä deux composants sont des mécanismes d'une importance notoire que beaucoup de bactéries utilisent pour faire face et répondre aux stimuli environnementaux. Le système à deux composants comprenant le senseur GacS et le régulateur de réponse GacA est très répandu chez les γ-protéobactéries et remplit des fonctions aussi diverses que la régulation du stockage de carbone ou l'expression de la virulence. Chez Pseudomonas fluorescens CHAO, une bactérie du sol qui protège les racines des plantes contre des attaques de champignons et nématodes pathogènes, le système à deux composants GacS/GacA est essentiel à la production de métabolites secondaires et d'exoenzymes requis pour l'activité de biocontrôle de la bactérie. La cascade régulatrice initiée pas GacS/GacA fait intervenir deux protéines répresseur de traduction, RsmA et RsmE, ainsi que trois petits ARNs RsmX, RsmY et RsmZ, dont la production est contrôlée par GacA. Ces petits ARNs ont pour rôle de contrecarrer l'action des protéines répressseur de la traduction, ce qui permet l'expression de facteurs de biocontrôle.
Des analyses génétiques ont révélé la présence de deux senseurs supplémentaires, appelés Rets et Lads, qui interviennent dans la cascade Gac/Rsm de P. fluorescens. L'impact de ces senseurs est, respectivement, négatif et positif. Ces interactions ont apparenunent lieu au niveau de GacS et permettent une modulation de l'expression des antibiotiques et de l'acide cyanhydrique, ainsi que du gène rpoS codant pour le facteur sigma du stress. La température s'est révélée être un facteur environnemental important qui influence la cascade Gac/Rsm. Il s'avère en effet que la production d'antibiotiques ainsi que d'acide cyanhydrique est moins importante à 35°C qu'à 30°C. L'implication du senseur Rets dans ce contrôle par la température a pu être démontrée.
La régulation positive du petit ARN RsmY par GacA et RsmA/RsmE a pu être confirmée; par le biais d'une analyse mutationelle, deux régions essentielles ont pu être mises en évidence dans la région promotrice de rsmY. Malgré le manque de preuves expérimentales directes, certains indices suggèrent que GacA puisse directement se fixer sur une des deux régions (appelée UAS), tandis que la deuxième région (appelée linker) serait plutôt reconnue par des facteurs intermédiaires (activateurs ou répresseurs) dépendant de RsmA/RsmE. En conclusion, ce travail a dévoilé de nouveaux éléments permettant d'éclairer les mécanismes de transduction des signaux dans la cascade Gac/Rsm
- …
