Segmented subwavelength silicon gratings manufactured by high productivity microelectronic technologies for linear to radial/azimuthal polarization conversion

International audienceA polarization rotation is realized by subwavelength binary gratings, where the round trip phases of thesmallest grating modes are fixed to the smallest possible integer numbers of 2π allowing a phase difference of πbetween TE and TM polarizations and almost 100% transmission. The principle is applied to a polarization transformationin the 1030 to 1064-nm wavelength range, using a segmented polarization rotating element convertinga linearly polarized incidence to a radial or azimuthal polarization distribution. The elevated costs of such kindsof polarization transformers based on assembled birefringent crystals are avoided by using mass-fabricationcompatible silicon-on-insulator technology on a wafer scale. It shows the general potential of microelectronictechnology, concerning the batch manufacturing of wavelength-scale diffractive, grating-based elements forprocessing free space waves

Smallest aspect-ratio form-birefringence half-wave plate

International audienceSubwavelength 0th order gratings permit to create a phase-shift between the polarized 0th order grating modes propagating down the slits and grooves of a binary corrugation, and to transform the polarization of an incident beam. The phase-shift per unit height of the grating is an increasing function of the refractive index difference between ridges and grooves. If the ridges are made by photolithography in a resist or by polymer embossing, the low refractive index leads to a very large corrugation aspect ratio (approx. 4 for a half-wave phase-shift) that is difficult to fabricate and/or provides insufficient mechanical stability. If the ridges are made in a high index non-organic material (e.g. a semiconductor) the needed depth is reduced (although still notably larger than 1 for a half-wave phase-shift). However, in this case due to a more significant Fabry-Perot effect between the upper and lower boundaries of the 0th order grating, high transmission is guaranteed only if its resonance condition is ensured for both polarizations simultaneously. Using an inventive design by phase management of the involved grating modes we have found that all three conditions (pi phase-shift between TE and TM and both Fabry-Perot resonances) can indeed be satisfied in a binary grating of reasonable aspect ratio when the substrate has a refractive index notably smaller than the ridges

Boosting Autobiographical Memory and the Sense of Identity of Alzheimer Patients Through Repeated Reminiscence Workshops?

peer reviewedDespite severe amnesia, some studies showed that Alzheimer Disease (AD) patients with moderate to severe dementia keep a consistent, but impoverished representation of themselves, showing preservation of the sense of identity even at severe stages of the illness. Some studies suggest that listening to music can facilitate the reminiscence of autobiographical memories and that stimulating autobiographical memory would be relevant to support the self of these patients. Consequently, we hypothesized that repeated participation to reminiscence workshops, using excerpts of familiar songs as prompts would participate to the enrichment of autobiographical memories, self-representation and sense of identity. We included a group of 20 AD patients with severe dementia residing in nursing homes. Their performances were compared to a control group of 20 matched (age, education, mood) healthy residents living in the same institutions. The experiment was conducted in three phases over a 2-week period. On phase 1, an individual assessment of sense of identity was proposed to each participant. On phase 2, participants joined musical reminiscence workshops (six sessions over 2 weeks for AD patients and 3 sessions over a week for controls). During the third phase (12 days after the first assessment), individual evaluation of autobiographical memory and a second assessment of sense of identity were proposed. Our results showed that, despite their massive amnesia syndrome, autobiographical memories of AD reached at the end of the 2 weeks the number and quality of those of matched controls. Moreover, we confirmed a continuity of self-representation in AD patients with a stable profile of the answers between the first and second individual assessments of sense of identity. However, the increase in number and episodic quality of autobiographical memories was not accompanied by an enrichment of the sense of identity. In a complementary study, new patients participated in the same paradigm, but using movie extracts as prompts, and showed very similar effects. We discuss all of these results with regard to the literature showing the significant impact of repetition on the reactivation of memory traces even in very amnestic AD patients at severe stages of the disease

Widespread horse-based mobility arose around 2200 BCE in Eurasia.

Horses revolutionized human history with fast mobility1. However, the timeline between their domestication and their widespread integration as a means of transport remains contentious2-4. Here we assemble a collection of 475 ancient horse genomes to assess the period when these animals were first reshaped by human agency in Eurasia. We find that reproductive control of the modern domestic lineage emerged around 2200 BCE, through close-kin mating and shortened generation times. Reproductive control emerged following a severe domestication bottleneck starting no earlier than approximately 2700 BCE, and coincided with a sudden expansion across Eurasia that ultimately resulted in the replacement of nearly every local horse lineage. This expansion marked the rise of widespread horse-based mobility in human history, which refutes the commonly held narrative of large horse herds accompanying the massive migration of steppe peoples across Europe around 3000 BCE and earlier3,5. Finally, we detect significantly shortened generation times at Botai around 3500 BCE, a settlement from central Asia associated with corrals and a subsistence economy centred on horses6,7. This supports local horse husbandry before the rise of modern domestic bloodlines

Apport de l'IRM de perfusion et de la spectroscopie par résonance magnétique dans les tumeurs musculo-squelettiques (revue de la littérature)

LILLE2-BU Santé-Recherche (593502101) / SudocSudocFranceF

Linear to radial/azimuthal polarization converter in transmission using form birefringence in a segmented silicon grating manufactured by high productivity microelectronic technologies

International audienceA polarization rotation is realized by subwavelength binary gratings, where the TE and TM round trip phases of the smallest grating modes are fixed to the smallest possible integer numbers of 2pi that allow a straight-through phase difference of pi This results in a subwavelength grating allowing to realize a half-wave element of almost 100% transmission. The principle is applied to a polarization transformation in the 1030-1064 nm wavelength range, using a segmented polarization rotating element converting a linearly polarized incidence to a radial or azimuthal polarization distribution. The elevated costs of such kind of polarization transformers based on assembled birefringent crystals are avoided by using mass-fabrication compatible silicon on insulator technology on a wafer scale. It shows the general potential of microelectronic technology, concerning the batch manufacturing of wavelength-scale diffractive, grating based elements for processing free space waves

Aspects radiologiques des tumeurs naso-sinusiennes de l'enfant

Objectifs : Décrire et illustrer l aspect en imagerie des principales tumeurs naso-sinusiennes de l enfant. Proposer un protocole d imagerie en fonction du diagnostic suspecté. Définir les points-clés de la lecture de l examen d imagerie et les critères orientant vers une pathologie bénigne ou maligne. Déterminer quelles tumeurs présentent un aspect typique en imagerie. Matériels et méthode: 26 patients (âge moyen : 4ans 7mois) du CHRU de Lille présentant un syndrome tumoral naso-sinusien ont été inclus sur une période de 11 ans. Il s agissait de 8 lésions malignes et de 18 lésions bénignes. L imagerie initiale (scanner ou IRM) a été relue selon une grille de lecture comportant les critères suivants: taille, forme, contours lésionnels, homogénéité et type de signal en IRM, type de rehaussement, topographie et extension extra-sinusienne, modifications osseuses. Résultats : l IRM était l examen de choix dans le bilan tumoral initial, à part pour le diagnostic de kyste lacrymo-nasal où le scanner seul était suffisant. Un scanner sans injection complémentaire était utile afin de rechercher une ostéolyse. Les critères les plus pertinents en faveur de la malignité étaient: l atteinte de plusieurs cavités sinusiennes, une extension extra-sinusienne, une forme tumorale non définie et une ostéolyse. A l inverse, une petite taille (< 3cm), une forme ovoïde ou ronde, une localisation sinusienne unique, l absence d extension extra-sinusienne ou d ostéolyse étaient en faveur de la bénignité. Les aspects les plus typiques en imagerie étaient le kyste lacrymo-nasal, le kyste osseux anévrysmal, le fibrome naso-pharyngien et le méningocèle. Les deux tumeurs les plus atypiques étaient l histiocytose et la pseudo-tumeur inflammatoire. Conclusion : Le bilan d imagerie initial d une tumeur naso-sinusienne chez l enfant est fondamental car il joue un rôle essentiel dans la décision et la prise en charge thérapeutique. Il est donc important pour le radiologue d en connaître les spécificités, afin de choisir un protocole d imagerie optimal, de réaliser un compte-rendu détaillé et pertinent, et de pouvoir donner une orientation diagnostique à l issue du bilan.LILLE2-BU Santé-Recherche (593502101) / SudocSudocFranceF

Un puits à roue élévatrice de Kition-Bamboula : les restes fauniques

La fouille du puits 883, menée par la mission française de Kition à Bamboula (2017-2018), a livré de nombreux restes fauniques au sein d’un comblement daté du ive siècle apr. J.‑C. Cet article présente les résultats d’une étude collaborative réalisée par des archéozoologues qui ont mis en évidence une grande diversité animale (bétail, carnivores, coquillages, oiseaux, rongeurs, reptiles, poissons). Ce matériel faunique offre l’opportunité d’aborder le paysage animalier d’un secteur de la ville antique dans sa multiplicité, avec des animaux liés directement aux pratiques économiques et domestiques (élevage, consommation carnée, utilisation d’animaux auxiliaires) dont les déchets s’avèrent de différentes natures (alimentaires, équarrissage, cadavres animaux). D’autres espèces, plus discrètes, ont su profiter des déchets et denrées produites par les habitants de ce quartier, témoignant ainsi de la porosité entre contextes urbanisés et environnements naturels.Η ανασκαφή του πηγαδιού 883, που πραγµατοποιήθηκε από την γαλλική αρχαιολογική αποστολή του Κιτίου στη θέση Παµποῦλα (2017-2018), έφερε στο φως πληθώρα αρχαιοζωολογικών καταλοίπων από επίχωση που χρονολογείται στον 4ο αιώνα µ.Χ. Το παρόν άρθρο παρουσιάζει τα αποτελέσµατα της µελέτης που πραγµατοποίησε οµάδα αρχαιοζωολόγων και η οποία κατέδειξε την παρουσία µεγάλης ποικιλίας ζώων (βοοειδή, σαρκοφάγα, µαλάκια, πτηνά, τρωκτικά, ερπετά, ψάρια).Το αρχαιοζωολογικό υλικό προσφέρει την δυνατότητα ανασύστασης της ποικιλίας του φάσµατος του ζωικού κόσµου σε έναν τοµέα της αρχαίας πόλης, και της σύνδεσης των ζώων µε τις οικονοµικές και οικιακές δραστηριότητες (κτηνοτροφία, κατανάλωση κρέατος, χρήση βοηθητικών ζώων), όπως αποκαλύπτουν οι ποικίλοι τύποι καταλοίπων (διατροφικά, δευτερογενείς χρήσεις του σκελετού, απόρριψη κουφαριών). Η µελέτη υπέδειξε και την παρουσία ζώων λιγότερο ευδιάκριτων αρχαιολογικά, τα οποία εκµεταλλεύονταν τα διατροφικά κατάλοιπα και λοιπές απορρίψεις των κατοίκων αυτού του οικιστικού τοµέα, στοιχείο που υπογραµίζει την διαπερατότητα ανάµεσα στα αστικά τοπία και στο φυσικό περιβάλλον.The excavation of the well 883, carried out by the French Archaeological Mission of Kition at Bamboula (2017-2018), yielded numerous faunal remains from a fill dating from the 4th century AD. This article presents the results of a collaborative zooarchaeological study that revealed a broad range of animal remains (cattle, carnivores, shells, birds, rodents, reptiles and fish). The faunal material found provides the opportunity to reconstruct the multiplicity of the animal landscape within a sector of the ancient town, with animals directly related to the economic and domestic activities (breeding, meat consumption, use of auxiliary animals) as suggested by the variable nature of the remains (food waste, rendering of animal carcasses, disposal of dead animals). The indirect presence of more discrete species, which took advantage of the food and other waste produced by the inhabitants of this town district, proves the permeability between urban contexts and natural environments

Dopage sportif à la méthandiénone : intérêt des antennes médicales de prévention du dopage

International audienc