97 research outputs found
Traversing the Schrödinger Bridge Strait: Robert Fortet’s Marvelous Proof Redux
No full textIn the early 1930s, Erwin Schrödinger, motivated by his quest for a more classical
formulation of quantum mechanics, posed a large deviation problem for a cloud of
independent Brownian particles. He showed that the solution to the problem could
be obtained through a system of two linear equations with nonlinear coupling at the
boundary (Schrödinger system). Existence and uniqueness for such a system, which
represents a sort of bottleneck for the problem, was first established by Fortet in
1938/1940 under rather general assumptions by proving convergence of an ingenious
but complex approximation method. It is the first proof of what are nowadays called
Sinkhorn-type algorithms in the much more challenging continuous case. Schrödinger
bridges are also an early example of the maximum entropy approach and have been
more recently recognized as a regularization of the important optimal mass transport
problem. Unfortunately, Fortet’s contribution is by and large ignored in contemporary
literature. This is likely due to the complexity of his approach coupled with an idiosyncratic
exposition style and due to missing details and steps in the proofs. Nevertheless,
Fortet’s approach maintains its importance to this day as it provides the only existing
algorithmic proof, in the continuous setting, under rather mild assumptions. It can be
adapted, in principle, to other relevant optimal transport problems. It is the purpose
of this paper to remedy this situation by rewriting the bulk of his paper with all the
missing passages and in a transparent fashion so as to make it fully available to the
scientific community.We consider the problem in Rd rather than in R and use asmuch
as possible his notation to facilitate comparison
3D models related to the publication: The world’s largest worm lizard: a new giant trogonophid (Squamata: Amphisbaenia) with extreme dental adaptations from the Eocene of Chambi, Tunisia
No full textInternational audienceThis contribution contains the 3D models described and figured in the following publication: Georgalis, G.L., K.T. Smith, L. Marivaux, A. Herrel, E.M. Essid, H. Khayati Ammar, W. Marzougui, R. Temani and R. Tabuce. 2024. The world’s largest worm lizard: a new giant trogonophid (Squamata: Amphisbaenia) with extreme dental adaptations from the Eocene of Chambi, Tunisia. Zoological Journal of the Linnean Society. https://doi.org/10.1093/zoolinnean/zlae13
A multi-modal dance corpus for research into real-time interaction between humans in online virtual environments
No full textWe present a new, freely available, multimodal corpus for research into, amongst other areas, real-time realistic interaction between humans in online virtual environments. The specific corpus scenario focuses on an online dance class application scenario where students, with avatars driven by whatever 3D capture technology are locally available to them, can learn choerographies with teacher guidance in an online virtual ballet studio. As the data corpus is focused on this scenario, it consists of student/teacher dance choreographies concurrently captured at two different sites using a variety of media modalities, including synchronised audio rigs, multiple cameras, wearable inertial measurement devices and depth sensors. In the corpus, each of the several dancers perform a number of fixed choreographies, which are both graded according to a number of specific evaluation criteria. In addition, ground-truth dance choreography annotations are provided. Furthermore, for unsynchronised sensor modalities, the corpus also includes distinctive events for data stream synchronisation. Although the data corpus is tailored specifically for an online dance class application scenario, the data is free to download and used for any research and development purposes
Audiovisual Analysis of Music Performances: Overview of an Emerging Field
No full textIn the physical sciences and engineering domains, music has traditionally been considered an acoustic phenomenon. From a perceptual viewpoint, music is naturally associated with hearing, i.e., the audio modality. Moreover, for a long time, the majority of music recordings were distributed through audio-only media, such as vinyl records, cassettes, compact discs, and mp3 files. As a consequence, existing automated music analysis approaches predominantly focus on audio signals that represent information from the acoustic rendering of music.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Multimedia Computin
clinical isolates
No full textAyed A, Essid R, Mankai H, et al. Synergistic antifungal activity and potential mechanism of action of a glycolipid like compound produced by Streptomyces blastmyceticus S108 against Candida clinical isolates. Journal of Applied Microbiology . 2023: lxad246.AIM: The present study aimed to investigate a novel antifungal compound produced by Streptomyces blastmyceticus S108 strain. Its effectiveness against clinical isolates of Candida species and its synergistic effect with conventional antifungal drugs were assessed and its molecular mechanism of action was further studied against C. albicans.; METHODS AND RESULTS: A newly isolated strain from Tunisian soil, Streptomyces blastmyceticus S108, showed significant antifungal activity against Candida species by well diffusion method. The butanolic extract of S108 strain supernatant exhibited the best anti-Candida activity with a minimal inhibitory concentration (MIC) value of 250 mug mL-1, determined by the microdilution method. The bio-guided purification steps of the butanolic extract were performed by chromatographic techniques. Among the fractions obtained, F13 demonstrated the highest level of activity, displaying a MIC of 31.25 mug mL-1. Gas Chromatography-Mass Spectrometry (GC-MS) and Electrospray Ionisation Mass Spectrometry (ESI-MS) analyses of this fraction (F13) revealed the glycolipidic nature of the active molecule with a molecular weight of 685.6 m/z. This antifungal metabolite remained stable to physicochemical changes and did not show hemolytic activity even at 4 MIC corresponding to 125 g mL-1 towards human erythrocytes. Besides, the glycolipid compound was combined with 5-flucytosine and showed a high synergistic effect with a FICI value 0.14 against C. albicans ATCC 10231. This combination resulted in a decrease of MIC values of 5-flucytosine and the glycolipid-like compound by 8 and 64-fold, respectively. The examination of gene expression in treated Candida albicans cells by qPCR revealed that the active compound tested alone or in combination with 5-flucytosine blocks the ergosterol biosynthesis pathway by down regulating the expression of ERG1, ERG3, ERG5, ERG11 and ERG25 genes.; CONCLUSION AND IMPACT OF THE STUDY: The new glycolipid like compound, produced by Streptomyces S108 isolate, could be a promising drug for medical use against pathogenic Candida isolates. © The Author(s) 2023. Published by Oxford University Press on behalf of Applied Microbiology International
Total Factor Environmental Productivity in the Mediterranean Countries: A Malmquist–Luenberger Index Approach
No full textThis paper examines the environmental productivity in the Mediterranean countries over the period 2009-2014.We use the Malmquist-Luenberger productivity index (MLPI) that can handle undesirable outputs within Data Envelopment Analysis (DEA) approach. We decompose the MLPI index into technical efficiency, technological change and scale efficiency change in order to determine the source of productivity changes. Empirical findings indicate that the total factor environmental productivity in the Mediterranean countries have a negative developmental trend. Furthermore, we find that technological progress is the main source of productivity growth. Finally, Mediterranean countries need a considerable effort on R&D to optimize the potential for technical development and enhance the environmental efficiency levels
Transient modeling with a frequency-transform subspace algorithm and "transient+sinusoidal" scheme
No full text[Introduction to] Writing Centers at the Center of Change
No full textWriting Centers at the Center of Change looks at how eleven centers, internationally, adapted to change at their institutions, during a decade when their very success has become a valued commodity in a larger struggle for resources on many campuses.
Bringing together both US and international perspectives, this volume offers solutions for adapting to change in the world of writing centers, ranging from the logistical to the pedagogical, and even to the existential. Each author discusses the origins, appropriate responses, and partners to seek when change comes from within a school or outside it. Chapters document new programs being formed under changing circumstances, and suggest ways to navigate professional or pedagogical changes that may undermine the hard work of more than four decades of writing-center professionals.
The book’s audience includes writing center and learning-commons administrators, university librarians, deans, department chairs affiliated with writing centers. It will also be useful for graduate students in composition, rhetoric, and academic writing.https://scholarship.richmond.edu/bookshelf/1353/thumbnail.jp
Synergistic Antileishmanial Activity of Erythrodiol, Uvaol, and Oleanolic Acid Isolated from Olive Leaves of cv. Chemlali
No full textThis is an accepted version of the following published document: Lafi O, Essid R, Lachaud L, et al (2023) Synergistic antileishmanial activity of erythrodiol, uvaol, and oleanolic acid isolated from olive leaves of cv. Chemlali. 3 Biotech 13:395. https://doi.org/10.1007/s13205-023-03825-3.
This version of the article has been accepted for publication, after peer review (when applicable) and is subject to Springer Nature’s AM terms of use, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at: https://doi.org/10.1007/s13205-023-03825-3.[Abstract] This study aimed to assess the antileishmanial activity of biomolecules obtained from Olea europaea L. leaves and twigs recovered from eight Tunisian cultivars. The extraction was first carried out with 80% methanol, and then the obtained extract was fractionated using three solvents of increasing polarity: cyclohexane (CHX), dichloromethane (DCM) and ethyl acetate (EtOAc). The antileishmanial activity was determined against leishmanial strains responsible for cutaneous, visceral, and mucocutaneous leishmaniasis. The cyclohexane fraction of the leaves of cv. Chemlali from the region of Sidi-Bouzid exhibited the strongest leishmanicidal activity against all the tested leishmanial strains. The inhibition concentrations (IC50) were 16.5, 14.5, and 7.4 μg mL−1 for Leishmania mexicana (cutaneous), Leishmania braziliensis (mucocutaneous), and Leishmania donovani (visceral), respectively. Interestingly, low cytotoxicity was observed on THP-1 cells with selective indexes (SI) ranging from 22.8 to 50.5. HPLC-HRMS and full-house NMR analysis allowed the identification of three triterpenic compounds, oleanolic acid (IC50 = 64.1 μg mL−1), erythrodiol (IC50 = 52.0 µg mL−1), and uvaol (IC50 = 53.8 μg mL−1). Antileishmanial activity of uvaol and oleanolic acid has been previously reported. However, this work constitutes the first report of the antileishmanial activity of erythrodiol which showed combinatorial interaction with uvaol (IC50 = 26.1 μg mL−1) against Leishmania tropica. The mixture of the three compounds, as major ones, exhibited an enhanced activity against Leishmania tropica (IC50 = 16.3 µg mL−1) compared to erythrodiol alone or the combination of uvaol and erythrodiol. This finding is of great importance and needs further investigation.The research leading to this paper was funded by the Tunisian Ministry of Higher Educatio
Compositional profile of food supplements for honeybees
No full textMestrado de dupla diplomação com a Université Libre de TunisHoneybees (Apis mellifera L.) are the main pollinating agents for numerous
plants and fruit trees and, hence, play a key role in agriculture and more generally in
the maintenance of ecological biodiversity.
Like the most of organisms, honeybees need a diverse diet consisting of
minerals, carbohydrates (sugars), fats, and amino acids (proteins) to survive and
reproduce. An adult honey bees carbohydrate requirement is satisfied by the nectar
produced in flowers and also occasionally from extra floral nectarines or honeydew
secreted by plant-feeding insects, while, flower pollen is the main source of amino
acids, protein building blocks, largely used to feed developing larvae and young
bees to provide structural elements of muscles, glands and other tissues.
Bee-population declines are linked to nutritional shortages caused by land-use
intensification, which reduces diversity and abundance of plant species. Together
with the deficiency caused by adverse climatic changes and with the need to reduce
colony mortality and particularly to ensure good nutritional/health status of bees in
specific production moments, artificial supplementation of honeybee colonies
became a major issue in beekeeping, and now is a common and growing practice
within Portuguese beekeepers. This practice, in association with the reduced
regulation in this area is leading to the proliferation of commercial products based
on carbohydrates, protein and other substances of diverse origins and compositions.
The impact of these products on hives may enable the beekeeper to remedy colony
imbalances resulting from adverse or beekeeping conditions, but also may pose
risks to the bee’s health and the bee products quality, depending on the used raw
materials and the presence of harmful substances.
The present work, inserted within the project ApisCibus - Artificial food for
honeybees: quality survey, digestibility and performance on the bee hive, will have as
main objective to evaluate the quality of commercial honeybee artificial
supplementation through composition analysis of commercial supplements. The quality parameters evaluated are: minerals quantified through atomic absorption
spectroscopy, fatty acids analyzed by gas chromatography coupled to mass
spectrometry (GC-MS) and amino acids which are analyzed by ultra-performance
liquid chromatography coupled with electro spray ionization mass spectrometry
(UPLC-ESI-MS). Food supplements that are analyzed are largely used by
beekeepers without knowing if they are benefic or not, toxic or not on the health of
bees.
Furthermore the results of the analysis shows that what is represented on the
labels of products could be not exactly the same amounts of the real product inside
the package. It shows also that some products may be considered as benefic or as
toxic depending on the amount of these micronutrients.
To continue this work in order to confirm these hypothesis, in vitro tests could
be done on honeybees using these products analyzed in this thesis.
Through the obtained results we could observe that the high amount of free
amino acids presented in the studied supplements does not necessarily reflect a
good source of nutrients, considering that for the bee it is important to have access
to a diverse set of amino acids. Bee's nutritional requirements require 10 essential
amino acids (Arg, Phe, His, Ile, Leu, Lys, Met, Thr, Trp and Val). The supplement
P12 appears as the richest and most balanced, followed by P05. The C08
supplement, although containing an adequate proportion in most amino acids, has
an excessive amount of Arg, which may cause adverse effects.
Regarding fatty acids, the samples presented several compounds, among
which the most abundant were hexanoic acids, 9-octadecenoic acid (oleic acid) and
9,12-octadecadenoic acid (linoleic acid).
Although the role of fatty acids in bee nutrition is not yet fully understood,
compounds such as linoleic acid, linolenic acid, myristic acid and dodecanoic acid
appear to play an important role in inhibiting some microorganisms that affect bees,
as Paenibacillus larvae larvae (American foulbrood). For this reason the sample P05 appears as the one with the highest nutritional quality, since it presented a higher
number of fatty acids. In the analysis of minerals, it was observed that protein foods
are significantly richer in micronutrients. In this work, the most common elements
were potassium, sodium, calcium and magnesium, while copper and manganese
appeared in some foods in small quantities. Cadmium, often an associated element
with heavy metal contamination appeared in only one of the products, P05, but in
very small quantities, lead was not detected in any of the supplements.
In general, there were discrepancies between the results obtained and the
description available on product labels, making clear the need for further quality
control of these commercial products.As abelhas melíferas (Apis mellifera L.) são os principais agentes
polinizadores de inúmeras plantas e árvores frutíferas e, portanto, desempenham um
papel fundamental na agricultura e, de maneira mais geral, na manutenção da
biodiversidade ecológica. Como a maioria dos organismos, as abelhas precisam de
uma dieta diversificada, composta de minerais, hidratos de carbono, lípidos e
aminoácidos (proteínas) para sobreviver e se reproduzir. A necessidade de hidratos
de carbono de uma abelha adulta é satisfeita pelo néctar produzido pelas flores e
também, ocasionalmente, por meladas segregadas por insetos, enquanto o pólen de
flores é a principal fonte de aminoácidos, principais constituintes das proteínas,
tendo um papel preponderante no desenvolvimento de larvas e abelhas jovens,
fornecendo elementos estruturais de músculos, glândulas e outros tecidos.
O declínio das populações de abelhas está ligado à escassez nutricional
causada pela agricultura intensiva, que reduz a diversidade e a abundância de
espécies de plantas.Juntamente com a deficiência causada por alterações climáticas
adversas e com a necessidade de reduzir a mortalidade de colónias, particularmente
para garantir um bom estado nutricional/saúde das abelhas, a suplementação
artificial de colónias de abelhas tornou-se uma questão importante na apicultura,
sendo uma prática comum e crescente entre os apicultores portugueses. Esta prática,
associada à escassa regulamentação existente para este tipo de produtos, está a
aumentar a oferta comercial destes produtos.O impacto destes produtos nas
colmeias pode permitir ao apicultor remediar desequilíbrios existentes nas colónias,
resultantes de condições adversas ou de apicultura, mas também pode representar
riscos à saúde da abelha e à qualidade dos produtos apícolas, dependendo das
matérias-primas usadas e da presença de substâncias nocivas.
O presente trabalho, inserido no projeto ApisCibus - Alimentos artificiais para
abelhas: levantamento de qualidade, digestibilidade e desempenho sobre a colmeia,
teve como objetivo principal avaliar a qualidade de suplementos artificiais de abelhas comerciais através da análise da sua composição química. Os parâmetros de
qualidade avaliados foram: minerais, quantificados por espectroscopia de absorção
atómica, ácidos gordos,
Analisados por cromatografia gasosa acoplada a espectrometria de massas
(GC-MS) e aminoácidos analisados por cromatografia líquida de ultra-pressão
acoplada à espectrometria de massas por ionização por eletrospray (UPLC- ESIMS).
Através dos resultados obtidos pudemos observar que a elevada quantidade de
aminoácidos livres apresentada nos suplementos estudados, não reflete
necessariamente uma boa fonte de nutrientes, considerando que para a abelha é
importante ter acesso a um conjunto de aminoácidos diversificados. As exigências
nutricionais da abelha requerem 10 aminoácidos essenciais (Arg, Phe, His, Ile, Leu,
Lys, Met, Thr, Trp e Val).O suplemento P12 surge como o mais rico e equilibrado,
seguindo-se o P05. O suplemento C08, apesar de conter uma proporção adequada
na maioria dos aminoácidos, apresenta uma quantidade excessiva de Arg, o que
poderá provocar efeitos adversos. Relativamente aos ácidos gordos, as amostras
apresentaram diversos compostos, entre os mais abundantes os ácidos hexanóico,
ácido 9-octadecenóico (ácido oleico) e ácido 9,12-octadecadienóico (ácido
linoleico). Embora o papel dos ácidos gordos na nutrição das abelhas ainda não seja
totalmente compreendido, compostos
como o ácido linoleico, ácido linolénico, ácido mirístico e ácido dodecanóico
parecem ter um papel importante na inibição de alguns microorganismos que
afectam as abelhas, como Paenibacillus larvae larvae (Loque Americana). Por esta
razão a amostra P05 surge como a de maior qualidade nutricional, já que apresentou
um maior número de ácidos gordos. Na análise dos minerais, observou-se que os
alimentos proteicos são significativamente mais ricos em micronutrientes. Neste
trabalho, os elementos mais comuns foram o potássio, sódio, cálcio e magnésio,
enquanto cobre e o manganês surgiram em alguns alimentos em pequenas
quantidades. O cádmio, um elemento associado frequentemente com a
contaminação por metais pesados surgiu apenas num dos alimentos, P05, mas em quantidades muito reduzidas, já o chumbo não foi
detetado em nenhuma dos suplementos.
No geral, verificaram-se discrepâncias entre os resultados obtidos e a
descrição disponível nos rótulos dos produtos, tornando-se evidente a necessidade
de um maior controlo de qualidade destes produtos comerciais.The author thanks to Programa Apícola Nacional (2017-2019) for the funding to the
Apiscibus and to Fundação para a Ciência e Tecnologia (FCT) and FEDER inside the
Program PT2020 for the finantial support to CIMO (UID/AGR/00690/2019)
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