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See detailCaractérisation de disques de poussière exozodiacale par interférométrie stellaire en infrarouge proche et moyen
Marion, Lindsay ULg

Doctoral thesis (2017)

Nous savons aujourd’hui que notre système solaire n’est pas un cas isolé dans la galaxie et qu’il pourrait potentiellement en exister des milliers d’autres. La recherche de ces systèmes est devenue un ... [more ▼]

Nous savons aujourd’hui que notre système solaire n’est pas un cas isolé dans la galaxie et qu’il pourrait potentiellement en exister des milliers d’autres. La recherche de ces systèmes est devenue un centre d’intérêt majeur de la recherche en astrophysique au XXIème. La présence de poussière chaude et tiède est étroitement liée à la présence de planètes dans un système stellaire. En effet, elle provient généralement de la formation du système planétaire, du dégazage de comètes, et de collisions d’astéroides, comme c’est le cas dans notre système solaire. Il est donc devenu primordial de détecter et caractériser la poussière tiède/chaude autour d’étoiles en séquence principale. L’intérêt de l’étude des disques de débris tièdes/chauds est double : d’une part, les détecter et les caractériser nous permet d’obtenir plus d’informations sur la formation d’un éventuel système planétaire et sur la dynamique du système (mécanisme de piégeage de la poussière, ré-approvisionnement du disque de poussière chaudes à partir d’un disque de poussière plus froide, plus éloigné, présence de planètes qui nettoient le disque interne, etc) ; d’autre part, les disques de débris tièdes/chauds peuvent complètement masquer une planète lors de tentatives de détection en imagerie directe. Il convient donc de les détecter pour discriminer ces étoiles pour les missions futures de détection d’exoplanètes par imagerie directe. Le présent travail vise à poursuivre l’étude des disques tièdes/chauds commencée au début des années 2000. Dans un premier temps, nous recherchons la présence de compagnon au sein de l’échantillon d’étoiles dédiées au programme de détection d’exozodis afin de fournir un échantillon non biaisé pour la recherche de disques de débris tièdes/chauds. Grâce aux détections de compagnons, nous révisons également la statistique d’étoiles binaires de type spectral A. Ensuite, dans un nouvel échantillon défini spécifiquement à cet effet, nous étudions la corrélation possible entre présence de poussière tiède et chaude. Nous arrivons à la conclusion qu’il existe une corrélation entre présence de poussière tiède et chaude et que la poussière tiède pourrait donc servir de réservoir à la poussière chaude. Toutefois, pour confirmer ce résultat, d’autres études devront être menées. Ensuite, nous résumons les avancées réalisées au LBTI et mettons en exergue les progrès réalisés sur la méthode statistique de traitement de données pour des observations de nulling. Enfin, nous étudions le système de beta Pic au travers d’observations dans l’infrarouge moyen réalisées avec MIDI. Cette étude nous permet de conclure qu’il n’y a pas de poussière tiède dans les zones internes (~ 1.5 UA) du disque de Pic et que la poussière chaude qui cause un excès en infrarouge proche est probablement alimentée par le dégazage de comètes envoyées dans le système stellaire interne par la planète se trouvant aux environs de 9 UA. [less ▲]

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See detailPhysical properties of L-type asteroids: a link to the primordial Solar System?
Devogele, Maxime ULg

Doctoral thesis (2017)

A few years ago, asteroid polarimetry allowed to discover a class of asteroids exhibiting peculiar phase polarization curves, collectively called "Barbarians" from the prototype of this class, the ... [more ▼]

A few years ago, asteroid polarimetry allowed to discover a class of asteroids exhibiting peculiar phase polarization curves, collectively called "Barbarians" from the prototype of this class, the asteroid (234) Barbara. All such objects belong to the L visible plus near infrared based taxonomic class. The anomalous polarization has been tentatively interpreted in terms of high-albedo, spinel-rich Calcium-Aluminum inclusions (CAI) that could be abundant on the surfaces of some of these asteroids, according to their spectral reflectance properties and to analogies with CO3/CV3 meteorites. Such CAIs are among the oldest mineral assemblages ever found in the Solar System. Barbarians' surfaces could therefore be rich in this very ancient material and bring information on the early phases of planetary formation. During this thesis, a systematic campaign for photometric, polarimetric and spectroscopic characterization has been conducted. These observation campaigns allowed improving our general knowledge about these peculiar asteroids and highlighting the link between polarization and polarimetric properties. Our observation also allowed discarding the hypotheses involving peculiar shape for these asteroids. However, as it was suggested, a link between the presence of CAI and the polarimetric response was found. Our observations show that the relative abundance of CAI is correlated with the polarimetric inversion angle. This is the first time that a direct link between polarimetric and spectroscopic properties is found. [less ▲]

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See detailImprovement of battery life of iPhones Inertial Measurement Unit by using edge computing Application to cattle behavior
Debauche, Olivier ULg; Mahmoudi, Saïd; Manneback, Pierre et al

Conference (2017, October)

Smartphones, particularly iPhones, can be relevant instruments for researchers widely used around the world in multiple domains of applications such as animal behavior. iPhones are readily available on ... [more ▼]

Smartphones, particularly iPhones, can be relevant instruments for researchers widely used around the world in multiple domains of applications such as animal behavior. iPhones are readily available on the planet, contain many sensors and require no hardware development. They are equipped with high performance inertial measurement units (IMU) and absolute positioning systems analyzing users movements, but they can easily be diverted to analyze likewise the behaviors of domestic animals such as cattle. Using smartphones to study animal behavior requires the improvement of the autonomy to allow the acquisition of many variables at a high frequency over long periods of time on a large number of individuals for their further processing through various models and decision-making tools. Storing, treating data at the iPhone level with an optimal consumption of energy to maximize battery life was achieved by using edge computing on the iPhone. It reduced the size of the raw data by 42% on average by eliminating redundancies. The decrease in sampling frequency, the selection of the most important variables and postponing calculations to the cloud allowed also an increase in battery life by reducing of amount of data to transmit. [less ▲]

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See detailCeci n'est pas de l'abolitionnisme. Le régime juridique de la prostitution : un surréalisme à la belge?
André, Sophie ULg

in Revue de la Faculté de Droit de l'Université de Liège (2017)

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See detailPrevalence and capsular-polysaccharide type distribution of colonizing group B streptococci (GBS) isolated from recto-vaginal samples in pregnant women in Hanoï, Vietnam
MEEX, Cécile ULg; DEVEY, Anaïs ULg; PHAM HONG, Nhung et al

Poster (2017, October)

Background: The study was organized by the Belgian National Reference Center (NRC) for Streptococcus agalactiae or GBS, and carried out in Vietnam. The aim of the study was to determine the prevalence of ... [more ▼]

Background: The study was organized by the Belgian National Reference Center (NRC) for Streptococcus agalactiae or GBS, and carried out in Vietnam. The aim of the study was to determine the prevalence of GBS colonization among pregnant women in Hanoï and to characterize the capsular-polysaccharide (CPS) type of the isolated strains. Methods: For a 2-months period in 2015, 888 recto-vaginal swabs were collected in Bach-Mai-Hospital from pregnant women at 35-37 weeks’ gestation and were cultured for detection of GBS. Strains were stored and transferred to the Belgian NRC for further characterization. CPS-typing was performed by both latex agglutination and PCR (Poyart, 2007; Kong, 2008). Results: Among the 888 swabs, 111 were positive for GBS, that is a prevalence of colonization of 12.5%. A total of 90 strains were available for typing: 91,11% could be serotyped by latex agglutination and all the strains, including the 8 phenotypically non-typable strains, were successfully genotyped. CPS type V was the most prevalent (36.7%) followed by CPS types Ib (25.6%), III (21.1%), VI and VII (8.9% and 4.4%). CPS type II was found twice and serotype Ia was found once. CPS types IV, VIII and IX weren’t present in this population. Conclusion: With predominance of types V, Ib and III, this distribution of CPS-types of GBS colonizing pregnant women in Hanoï, Vietnam, differs from distributions described in Europe and in o Asian countries. This study provides useful information for the development of a universal vaccine that could contribute to improve the prevention of neonatal GBS infections. [less ▲]

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See detailEvolution of rate and genotypes of resistance to macrolide/lincosamide among invasive Group B Streptococcus (GBS): Development of a multiplex PCR tool for simultaneous detection of ErmB, ErmTr, MefA and LsaC resistance genes.
SACHELI, Rosalie ULg; DESCY, Julie ULg; MEEX, Cécile ULg et al

Poster (2017, October)

Methods: A multiplex-PCR, using a set of specifically designed or already described (Kataja, 1999; Malbruny, 2011) primers was developed and used to detect, in GBS, three genes for erythromyc resistance ... [more ▼]

Methods: A multiplex-PCR, using a set of specifically designed or already described (Kataja, 1999; Malbruny, 2011) primers was developed and used to detect, in GBS, three genes for erythromyc resistance, ermB, ermTR, mefA and one gene for clindamycin-resistance lsaC. AdhP gene amplification was used as control for GBS identification. All(219) GBS isolates from invasive infections in newborns and adults received by the Belgian National Reference Center for GBS in 2015, and control strains were tested for erythromycin/clindamycin susceptibility (disk-diffusion/broth- microdilution) and for detection of resistance genes. Results: PCR products demonstrated the expected respective sizes. The method has been validated successfully according to ISO15189 analytical requirements. Of the 219 isolates, 67(30,67%) w resistant to erythromycin and/or clindamycin: 44/67(65,78%) showed a constitutive-MLS phenotype and 10/67(14,9%) the inducible-MLS phenotype. Among the constitutive-MLS strains, 73% harboured ErmB gene, 13% ErmTR, 7% ErmB+mefA and 7% ermB together with LsaC gene. The inducible-MLS strains harboured mostly ErmTr gene (89%) and the others the ErmB gene. Among the 10/67(14,9%) GBS strains with an M-phenotype (isolated resistance to erythromycin), the MefA gene was exclusively detected. Among the 3(4,48%) strains showing an isolated resistance to clindamycin (L-phenotype), the LsaC gene was detected. Conclusion: The developed multiplex PCR is able to detect simultaneously four genes involved in MLS resistance in GBS. In 2015, 30,6% of the invasive GBS strains isolated in Belgium were resist to macrolides and/or lincosamides. The emergence of the L-phenotype in GBS described since 2010, justifies the relevance to also detect LsaC gene together with ErmB, ErmTr and MefA. [less ▲]

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See detailDu trou de ver au trou de serrure...
Gernay, Delphine; Moukhaiber, Sophie; Maenhout, Marine et al

in Revue des Hôpitaux de Jour Psychiatriques et des Thérapies Institutionnelles (2017), 19

See detailLecture phénoménologique du discours romanesque. Rhétorique du corps dans le roman existentialiste et le Nouveau Roman
Franck, Thomas ULg

Book published by Lambert-Lucas (2017)

Ce livre propose une lecture phénoménologique du discours romanesque, en particulier du roman existentialiste et du Nouveau roman dont les mutations rhétoriques sont profondément influencées par ce ... [more ▼]

Ce livre propose une lecture phénoménologique du discours romanesque, en particulier du roman existentialiste et du Nouveau roman dont les mutations rhétoriques sont profondément influencées par ce courant philosophique. L’impulsion de la phénoménologie, interrogation sur les rapports entre réalité phénoménale, conscience individuelle et corps sensible, permet aux romanciers de résoudre une série d’impasses propres au réalisme du XIXe, ce qui renforce le rôle dominant du genre romanesque dans la littérature et plus généralement dans la culture. Mettant au centre de ses réflexions l’appréhension du monde par des corps situés, orientés au sein d’une chair indivise, indissociable de ce qui la constitue comme signe, la philosophie de Merleau-Ponty propose des catégories et une série d’outils herméneutiques pour l’analyse critique des œuvres existentialistes et néo-romanesques, et en particulier du rôle qu’y joue la corporéité. La fécondité des catégories phénoménologiques merleau-pontiennes, ainsi mises à l’épreuve d’analyses rhétoriques de romans de Sartre, Beauvoir, Camus, Simon, Sarraute et Robbe-Grillet, permet d’envisager un enrichissement méthodologique de l’analyse du discours littéraire. [less ▲]

See detailFirst-principles study of tungsten trioxide:structurale properties and polaron formation
Hamdi, Hanen ULg

Doctoral thesis (2017)

Résumé L’oxyde de tungstène (WO 3 ) est un composé qui a été énormément étudié du fait de la richesse de ses propriétés physiques et de leurs utilisations pour des applications technologiques. En effet ... [more ▼]

Résumé L’oxyde de tungstène (WO 3 ) est un composé qui a été énormément étudié du fait de la richesse de ses propriétés physiques et de leurs utilisations pour des applications technologiques. En effet, WO 3 est le matériau électrochromique le plus connu grâce à sa capacité de changer de couleur de manière réversible lorsqu’il est soumis à des ondes électromagnétiques ou bien sous l’application d’un champ électrique. Au niveau industriel, les matériaux électrochromiques, dont WO 3 fait partie, sont utilisés principalement dans la fabrication de fentêres à haut rendement énergétique, de verres intelligents, de rétroviseurs anti-reflets, de toits ouvrants, de batteries ou de cristaux photoniques accordables. Il est intéressant de noter que toutes ces propriétés sont liées au dopage et donc directement à la formation de polarons et de bipolarons qui vont influencer les transporteurs de charges. Bien que ce composé ai été largement étudié expérimentalement et théoriquement, il reste encore des questions pertinentes et non résolues concernant les propriétés structurales de WO 3 et la caractérisation des polarons dans WO 3−x . Cette thèse est ainsi dédiée en premier temps, à analyser et comprendre les différentes tran- sitions de phase du WO 3 sur base de calculs ab-initio basés sur la théorie de la fonctionnelle de la densité (DFT) et de reproduire les mesures expérimentales. Plus particulièrement, nous avons montré que WO 3 est un matériau anti-ferroélectrique à l’état fondamental et que c’est possible de le rendre ferroélectrique sous l’application d’un champs électrique. En second temps, nous avons élargi nos précédentes études de WO 3 à l’état pur sans defaut, en explo- rant théoriquement les effets des lacunes d’oxygène sur les propriétés physiques de WO 3 . Nous avons discuté le développement du polaron, qui est due à l’ajout d’un électron extèrieur dans la supercellule de l’état fondamentale de WO 3 , en fonction de la taille de la supercellule en utilisant des calculs de premier principe. Nous avons ainsi confirmé des travaux expérimentaux précédents reliés au polaron dans WO3 . [less ▲]

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See detailEffect of different crop residue management on soil hydraulic properties - a study in a silt loam soil in Belgium
Parvin, Nargish ULg

Doctoral thesis (2017)

In recent decades, agriculture is challenged to develop strategies for sustainability which conserve non-renewable natural resources such as soil. Soil improving conservation systems aim at improving soil ... [more ▼]

In recent decades, agriculture is challenged to develop strategies for sustainability which conserve non-renewable natural resources such as soil. Soil improving conservation systems aim at improving soil functions and at the same time ensuring high productivity. Such soil management systems have to be adapted to climate and soil specific conditions, and may include reduced tillage, balanced crop rotation, retention of crop residues, cover crops, and appropriate timing of field operations. Changes in soil functions have huge impacts on environmental flows like hydrology, crop production, solute transfer, and CO2 emission at macroscale. Soil structure is considered as one of the key factors for soil functioning. The effect of different land management on soil structure and consequently on soil hydrodynamics is not fully understood and still under investigation. The main aim of this thesis was to evaluate the effect of crop residue management on soil structure by measuring soil hydraulic properties in pedon and core scale. The agronomic context was different crop residue management in a reduced tillage system. The experimental field is named as Solresidus located in Gembloux, Belgium. Since 2008, the field has been under conservation system. Different residue management includes reduced tillage with incorporation of crop residues (RT-in) and without incorporation (RT-out). A large part of this thesis was methodological development to obtain accurate results from experimentations. Many studies have been made and documented in literature to develop indirect methods to predict soil hydrology from soil water retention curve (SWRC). There is no measuring device available which can determine the SWRC over the entire soil moisture range. Therefore, one of the methodological developments was to obtain complete SWRC by combining three different methods in core scale: X-ray computed microtomography (X-ray CT), HYPROP evaporation and Richards pressure plate method to obtain the entire SWRC. The combination of these methods found well justified to obtain the accurate and complete SWRC. Saturated hydraulic conductivity (Ks), specific connectivity (SC) of soil pores and bulk density of the soil were also measured in core and pore scale. There were soil moisture sensors (capacitance sensors) in the field to observe the soil moisture dynamics in pedon scale. Another important methodological development was to obtain the calibration results with the moisture sensor according to the soil texture and horizons. Calibration results found quite satisfying to get the accurate moisture content of the field; it was also noticed that it could be over estimation of soil moisture without the calibration. Significantly, average higher moisture content was observed by the moisture sensors in RT-in than RT-out during the canopy formation to harvest of winter wheat in 2014. The SWRCs also showed that plant available water content was higher in RT-in than RT-out. SC of soil pores was also significantly higher at the surface soil of RT-in than RT-out. RT-in found to have significant positive effects on soil structure by reducing bulk density, increasing SC, Ks and retention of soil moisture during the observation period of this study. Crop yield was marginally higher and organic matter content was significantly higher in RT-in than RT-out (results from close collaboration). Therefore, reduced tillage with residues incorporation found to have better soil hydraulics together with better crop yield than reduced tillage without incorporation of crop residues. [less ▲]

Peer Reviewed
See detailThe EP’s ‘European Standards’ Resolution in the wake of James Elliott Construction: carving ever more holes in Pandora’s Box?
Van Cleynenbreugel, Pieter ULg; Demoulin, Iris ULg

E-print/Working paper (2017)

This blogpost analyses a recent Parliamentary resolution against the background of the Court of Justice's James Elliott Construction judgment, dealing with the legal nature of harmonised technical ... [more ▼]

This blogpost analyses a recent Parliamentary resolution against the background of the Court of Justice's James Elliott Construction judgment, dealing with the legal nature of harmonised technical standards in EU free movement law. [less ▲]

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See detailContraintes et stratégies d’amélioration de la filière maïs au Rwanda
Musabanganji, Edouard ULg

Doctoral thesis (2017)

For more than a decade, Rwanda has adopted a series of policies and strategies aimed at economic development and the improvement of the living conditions of its predominantly agricultural population. In ... [more ▼]

For more than a decade, Rwanda has adopted a series of policies and strategies aimed at economic development and the improvement of the living conditions of its predominantly agricultural population. In agriculture, implementation of these strategies and related programs has been accompanied by a series of advances in the adoption of farming technologies and increasing agricultural production. However, the country's economy is still characterized by subsistence agriculture, and for the maize sector in particular, the country is continuously depending on imports to meet domestic demand, and maize processing plants always operate below their productive capacity. This research aims to examine the level of competitiveness of this sector in the current production and marketing conditions in order to identify existing constraints and formulate the strategies that can improve the level of economic performance of maize production and maize marketing system. The data used to study the economic performance of maize production come from close monitoring of maize production activities on a sample of 50 producers from five maize producers’ cooperatives selected in the districts of Huye, Rusizi, Gasabo, Burera and Bugesera during two growing seasons. They were supplemented by direct observation, interviews with targeted resource persons, and focus group discussions. The analysis was done using group analysis and appropriate statistical methods. The study of the maize marketing system used the 'Structure-Conduct-Performance' model with data collected from a sample of 150 producers and 17 assemblers selected in the districts of Burera, Bugesera and Huye, and 15 transporters, 5 wholesalers and 15 retailers selected at the national market of Kigali. The results revealed that for many producers, the yield is very low compared to theoretical expected yields, production costs are higher and exceed sales prices, gross margin and family labor income are negative, and the gross added value created by maize producers is not high even though it is positive. The analysis showed that the increase in the selling price positively influences the gross margin, added value and family labor income, and that the rational use of improved seeds, chemical fertilizers and soil conditioners improves the yield. This clearly shows that improving the selling price and rational use of inputs can significantly contribute to making maize production a more profitable and income-generating activity. The study also identified challenges that hamper the production process. These include non-availability of, and low access to inputs, inadequate technical support, limited financial resources and low access to formal agricultural credit, high marshlands rental fee, method of fixing the maize floor price and lack of mechanisms ensuring its use by potential buyers, the lack of storage infrastructure, and the unsustainability of inputs subsidies granted by the government. At the marketing level, the results revealed that several actors are involved in the marketing of maize. The study also revealed that maize imported from Uganda is sold on domestic market at lower prices than locally produced maize, which attests the increase in the cost of maize production in Rwanda compared to Uganda and the low level of competitiveness of the local maize compared to Ugandan maize. The improved status of feeder roads and the high level of access to price information by actors were highlighted among the technological innovations that helped improve the marketing system of foodstuffs in general and maize in particular, which was also evidenced by the level of integration observed between districts maize markets and the national market of Kigali. However, the lack of enough capital and low access to formal credit were noted as major constraints by most of the chain actors. In the light of all these results, it is clear that the production and marketing of maize are not done in good conditions at all levels. This in turn undermines the sector's ability to respond adequately to domestic demand, generate income for actors and integrate itself into both domestic and regional markets. Therefore, strategies aiming at scaling-up the maize production and marketing, and improving working conditions of the sector operators were recommended. These strategies include the implementation of actions to improve access to finance by farmers and other actors; making inputs avail and accessible; reorganizing the marketing system especially in terms of fixing and using the floor price; making available storage facilities where necessary; improving the monitoring, training and sensitization of maize producers on farming techniques and the use of improved technologies; and harmonizing the marshland rental fee at national level. [less ▲]

Peer Reviewed
See detailSemantic externalism(s) and cognitive transparency
Leclercq, Bruno ULg; De Brabanter, Philippe

Conference (2017, September 22)

See detail‘Once Upon A Time’ ou le contrôle de la narration
Claisse, Frédéric ULg; Huppe, Justine ULg

E-print/Working paper (2017)

Ce billet de blog analyse les liens entre "ELIPSIA", une série de court-métrages réalisée par Frédéric DARRAS entre 2012 et 2016, et le projet de recherche STORYFIC, consacré aux effets du storytelling ... [more ▼]

Ce billet de blog analyse les liens entre "ELIPSIA", une série de court-métrages réalisée par Frédéric DARRAS entre 2012 et 2016, et le projet de recherche STORYFIC, consacré aux effets du storytelling sur l'écriture de fiction contemporaine, et plus particulièrement aux pouvoirs de la fiction. Après avoir décrit les enjeux posés par la série, l'article développe une série de parallèles avec les préoccupations d'auteurs français contemporains (C. Delaume, C. de Toledo, P. Vasset, A. Damasio), qui nourrissent le même rapport ambivalent à la fiction: à la fois dénoncée pour son emprise sur nos existences et son caractère aliénant, mais aussi valorisée pour ses promesses de réappropriation et d'émancipation. [less ▲]

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See detailTowards a covering aerospray method for quantitative analyses of pharmaceutical tablets using surface-enhanced Raman chemical imaging (SER-CI)
Cailletaud, Johan ULg; De Bleye, Charlotte ULg; Dumont, Elodie ULg et al

Conference (2017, September 22)

In recent years, the use of SERS-CI in pharmaceutical sciences has increased in order to study the distribution of low-dose compounds in solid dosage forms [1]. This technique allows to improve the ... [more ▼]

In recent years, the use of SERS-CI in pharmaceutical sciences has increased in order to study the distribution of low-dose compounds in solid dosage forms [1]. This technique allows to improve the sensitivity of conventional Raman microscopy and to reduce significantly the image acquisition time by exalting the signal information. However, the applications of SERS-CI in the pharmaceutical field remain limited, especially due to the difficulty of obtaining a homogeneous deposit of metallic nanoparticles on the sample surface. Generally, the covering method used on the tablet is a drop casting deposition due to its simplicity and rapidity of implementation. Despite the colloidal solution deposit is not fully controlled. The inhomogeneous covering is the result of the “coffee-ring” effect that concentrates the nanoparticles at the edges of the droplet [2]. This implies remarkable variations of the SERS analyte signal’s intensity at different places. For a more reproducible and homogeneous coating, an aerospray method using a homemade apparatus was developed (Figure 1). The device is composed with a pair of coaxial tubes, the colloidal solution is pulled through the inner tube from a syringe pump and the outer tube is connected to a source of high pressure gas. Nitrogen, used as a nebulizing gas, creates a flow of small droplets of nanoparticles that are nearly dry when they hit the sample surface. The aerospray device is easy to implement and the entire surface of the tablet is covered by the SERS substrate in a homogeneous way. By using this covering method, the potential of SERS-CI is improved and making it a suitable technique for quantitative analyses of low drug concentrations or impurities in pharmaceutical tablets. [less ▲]