Etude de l’étiologie bactérienne des mammites subcliniques des ovins à l’Est de l’Algérie

On s’est longtemps désintéressé des mammites chez la brebis sous prétexte que les mammites cliniques y sont peu fréquentes, les mammites subcliniques causent des pertes économiques et sanitaires importante passent le plus souvent inaperçues du fait de leur caractère discret. Leur prévalence n’est donc pas bien connue. Plusieurs germes sont associés à ce type de mammites et leur présence dans le lait peut avoir un impact négatif sur la santé des consommateurs. Dans le but d’étudier l’étiologie bactérienne des mammites subcliniques des ovins à l’Est algérien, zone réputée par sa densité de l’élevage ovin, 214 prélèvements de lait de brebis d’aspect normal ont été dépistés par le Califorinia mastitis test (CMT), dont les résultats positifs, pour passer aux tests bactériologiques. L’isolement bactérien n’a concerné que 19% des échantillons. Parmi les bactéries isolées, les Staphylocoques à coagulase négative (SCN) ont été les plus répandus des germes pathogènes (59%). Alors que seulement 14% pour les S. aureus. Les autres bactéries isolées ont été les entérobactéries (19%) et les bacillus (8%). On peut conclure que les mammites subcliniques sont causées principalement par les Staphylocoques à coagulase négative (SCN), et que la maitrise de cette pathologie multifactorielle nécessite un dépistage systématique et précoce à l’aide d’un test rapide et fiable comme le CMT.Mots-clés: bactériologie, mammites, ovin, CMT, Algérie. Study of the bacterial etiology of subclinical mastitis in sheep at the East of Algeria For a long time, the mastitis sheep were neglected on the basis that clinical mastitis are rare. Subclinical mastitis causes significant health and economic losses and usually passes without being noticed due to its confidential nature. Its prevalence is not well known. Many germs are associated with this type of mastitis and their presence in milk can have a negative impact on consumer health. In order to study the bacterial etiology of subclinical mastitis in sheep in the East of Algeria, an area reputable for its density in sheep, 214 milk samples ewes of normal appearance, were tested by California mastitis test (CMT), whose result was positive, to pursue other bacterial tests. Bacterial isolation concerned 19% of the samples. Among the pathogenic bacteria detected, coagulase-negative staphylococci (CNS) were the most frequently found (59%). While only 14% for S. aureus were found. Other bacteria isolated were enterobacteriaceae (19%) and bacillus (8%).It is concluded that subclinical mastitis is mainly caused by coagulase-negative staphylococci (CNS), and the mastery of this multifactorial disease requires a systematic and early detection using a fast and reliable test as CMT.Keywords: bacteriology, mastitis, sheep, CMT, Algeria

Universal metamaterial absorbe

We propose a design for an universal absorber, characterized by a resonance frequency that can be tuned from visible to microwave frequencies independently of the choice of the metal and the dielectrics involved. An almost resonant perfect absorption up to 99.8 % is demonstrated at resonance for all polarization states of light and for a very wide angular aperture. These properties originate from a magnetic Fabry-Perot mode that is confined in a dielectric spacer of $\lambda/100$ thickness by a metamaterial layer and a mirror. An extraordinary large funneling through nano-slits explains how light can be trapped in the structure. Simple scaling laws can be used as a recipe to design ultra-thin perfect absorbers whatever the materials and the desired resonance wavelength, making our design truly universal

Almost periodic solution in distribution for stochastic differential equations with Stepanov almost periodic coefficients

This paper deals with the existence and uniqueness of ($\mu$-pseudo) almost periodic mild solution to some evolution equations with Stepanov ($\mu$-pseudo) almost periodic coefficients, in both determinist and stochastic cases. After revisiting some known concepts and properties of Stepanov ($\mu$-pseudo) almost periodicity in complete metric space, we consider a semilinear stochastic evolution equation on a Hilbert separable space with Stepanov ($\mu$-pseudo) almost periodic coefficients. We show existence and uniqueness of the mild solution which is ($\mu$-pseudo) almost periodic in 2-distribution. We also generalize a result by Andres and Pennequin, according to which there is no purely Stepanov almost periodic solutions to differential equations with Stepanov almost periodic coefficients

Goos-Hänchen effect in the gaps of photonic crystals

We show the existence of a Goos-Hänchen effect when a monochromatic beam illuminates a photonic crystal inside a photonic band gap

Interface Dipole : Effects on Threshold Voltage and Mobility for both Amorphous and Poly-crystalline Organic Field Effect Transistors

We report a detailed comparison on the role of a self-assembled monolayer (SAM) of dipolar molecules on the threshold voltage and charge carrier mobility of organic field-effect transistor (OFET) made of both amorphous and polycrystalline organic semiconductors. We show that the same relationship between the threshold voltage and the dipole-induced charges in the SAM holds when both types of devices are fabricated on strictly identical base substrates. Charge carrier mobilities, almost constant for amorphous OFET, are not affected by the dipole in the SAMs, while for polycrystalline OFET (pentacene) the large variation of charge carrier mobilities is related to change in the organic film structure (mostly grain size).Comment: Full paper and supporting informatio

Optically optimal wavelength-scale patterned ITO/ZnO composite coatings for thin film solar cells

International audienceA methodology is proposed for finding structures that are, optically speaking, locally optimal : a physical analysis of much simpler structures is used to constrain the optimization process. The obtained designs are based on a flat amorphous silicon layer (to minimize recombination) with a patterned anti-reflective coating made of ITO or ZnO, or a composite ITO/ZnO coating. These latter structures are realistic and present good performances despite very thin active layers

Navigating through the COVID-19 pandemic. Unfinished learning in primary and secondary education in Tunisia

During the outbreak of the global SARS-CoV-2 (COVID-19) pandemic, Tunisia, like many countries, prepared an emergency plan to shift to distance learning to salvage the academic year and ensure continuous learning. However, a shortage of digital materials coupled with the fact that many households did not have adequate Internet bandwidth made it virtually impossible to secure adequate digital learning. When in-person schooling was restarted in 2020/21, primary, pre-secondary, and secondary school pupils attended school on alternate days to avoid overcrowding. As a result of the pandemic, the curriculum has been lightened, and the fundamentals have been prioritized. Based on a content analysis of the Ministry of Education documents and a survey conducted by the Ministry on remote learning, we shed light on the different measures taken to curb learning loss during the spread of the pandemic as well as the challenges facing Tunisian students and the government. The consequences of these measures are discussed along with future recommendations. (DIPF/Orig.