539 research outputs found

    Gaudin Algebras, RSK and Calogero-Moser cells in type A

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    We study the spectrum of a family of algebras, the inhomogeneous Gaudin algebras, acting on the nn-fold tensor representation C[x1,,xr]n\mathbb{C}[x_1, \ldots, x_r]^{\otimes n} of the Lie algebra glr\mathfrak{gl}_r. We use the work of Halacheva-Kamnitzer-Rybnikov-Weekes to demonstrate that the Robinson-Schensted-Knuth correspondence describes the behaviour of the spectrum as we move along special paths in the family. We apply the work of Mukhin-Tarasov-Varchenko, which proves that the rational Calogero-Moser phase space can be realised as a part of this spectrum, to relate this to behaviour at t=0t=0 of rational Cherednik algebras of Sn\mathfrak{S}_n. As a result, we confirm for symmetric groups a conjecture of Bonnaf\'e-Rouquier which proposes an equality between the Calogero-Moser cells they defined and the well-known Kazhdan-Lusztig cells.Comment: 24 page

    Ventral Premotor-Motor Cortex Interactions in the Macaque Monkey during Grasp: Response of Single Neurons to Intracortical Microstimulation

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    Recent stimulation studies in monkeys and humans have shown strong interactions between ventral premotor cortex (area F5) and the hand area of primary motor cortex (M1). These short-latency interactions usually involve facilitation from F5 of M1 outputs to hand muscles, although suppression has also been reported. This study, performed in three awake macaque monkeys, sought evidence that these interactions could be mediated by short-latency excitatory and inhibitory responses of single M1 neurons active during grasping tasks. We recorded responses of these M1 neurons to single low-threshold (<= 40 mu A) intracortical microstimuli delivered to F5 sites at which grasp-related neurons were recorded. In 29 sessions, we tested 232 M1 neurons with stimuli delivered to between one and four sites in F5. Of the 415 responses recorded, 142 (34%) showed significant effects. The most common type of response was pure excitation (53% of responses), with short latency (1.8-3.0 ms) and brief duration (similar to 1 ms); purely inhibitory responses had slightly longer latencies (2-5 ms) and were of small amplitude and longer duration (5-7 ms). They accounted for 13% of responses, whereas mixed excitation then inhibition was seen in 34%. Remarkably, a rather similar set of findings applied to 280 responses of 138 F5 neurons to M1 stimulation; 109 (34%) responses showed significant effects. Thus, with low-intensity stimuli, the dominant interaction between these two cortical areas is one of short-latency, brief excitation, most likely mediated by reciprocal F5-M1 connections. Some neurons were tested with stimuli at both 20 and 40 mu A; inhibition tended to dominate at the higher intensity

    2-я Международная конференция «Высокочистые материалы: получение, применения, свойства»

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    17–20 сентября 2013 года в Харькове проходила 2-я Международная конференция «Высокочистые материалы: получение, применения, свойства», посвященная памяти академика НАН Украины Владимира Михайловича Ажажи. В организации Конференции приняли участие: Национальная академия наук Украины, Отделение ядерной физики и энергетики НАНУ, Национальный научный центр «Харьковский физико-технический институт», Харьковский национальный университет им. В.Н. Каразина. В работе Конференции приняло участие более 50 человек

    Superfluid fraction in an interacting spatially modulated Bose-Einstein condensate

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    At zero temperature, a Galilean-invariant Bose fluid is expected to be fully superfluid. Here we investigate theoretically and experimentally the quenching of the superfluid density of a dilute Bose-Einstein condensate due to the breaking of translational (and thus Galilean) invariance by an external 1D periodic potential. Both Leggett's bound fixed by the knowledge of the total density and the anisotropy of the sound velocity provide a consistent determination of the superfluid fraction. The use of a large-period lattice emphasizes the important role of two-body interactions on superfluidity

    Peri-urban Farn ing Systems and Food Processing in the Congo

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    Abstract AGRICONGO (Institut de recherche et d&apos;appui pour le développement agricole en Zones tropicales) developed a project entitled new farming systems (NSF). This project is intended to implement peri-urban agriculture for city dwellers who want to go into small farm businesses. Because the Congo is importing a large part of its food, the project&apos;s first goal was to identify products for development. A basic project assumption was that the best way to reduce these imports was to modernize traditional foods. There was also a need to develop appropriate technologies in agronomy and food science. Work was done to design both a 1.5 ha NFS farm and an integrated food processing facility. Farming techniques were tested at the research station level and the study included socioeconomic issues and farmer-level implementation of product marketing and commercialization. This report presents preliminary findings from 20 pilot NFS farms that were tested near Brazzaville. Food processing lines and their management are also described. Processed products made available to urban markets through the project were chikwangue (cassava bread) and cassava-based mixed flour for infant food

    Dusty core disease (DuCD): expanding morphological spectrum of RYR1 recessive myopathies

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    Several morphological phenotypes have been associated to RYR1-recessive myopathies. We recharacterized the RYR1-recessive morphological spectrum by a large monocentric study performed on 54 muscle biopsies from a large cohort of 48 genetically confirmed patients, using histoenzymology, immunohistochemistry, and ultrastructural studies. We also analysed the level of RyR1 expression in patients' muscle biopsies. We defined "dusty cores" the irregular areas of myofibrillar disorganisation characterised by a reddish-purple granular material deposition with uneven oxidative stain and devoid of ATPase activity, which represent the characteristic lesion in muscle biopsy in 54% of patients. We named Dusty Core Disease (DuCD) the corresponding entity of congenital myopathy. Dusty cores had peculiar histological and ultrastructural characteristics compared to the other core diseases. DuCD muscle biopsies also showed nuclear centralization and type1 fibre predominance. Dusty cores were not observed in other core myopathies and centronuclear myopathies. The other morphological groups in our cohort of patients were: Central Core (CCD: 21%), Core-Rod (C&amp;R:15%) and Type1 predominance "plus" (T1P+:10%). DuCD group was associated to an earlier disease onset, a more severe clinical phenotype and a lowest level of RyR1 expression in muscle, compared to the other groups. Variants located in the bridge solenoid and the pore domains were more frequent in DuCD patients. In conclusion, DuCD is the most frequent histopathological presentation of RYR1-recessive myopathies. Dusty cores represent the unifying morphological lesion among the DuCD pathology spectrum and are the morphological hallmark for the recessive form of disease

    Nanocomposites with functionalised polysaccharide nanocrystals through aqueous free radical polymerisation promoted by ozonolysis

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    Cellulose nanocrystals (CNC) and starch nanocrystals (SNC) were grafted by ozone-initiated free-radical polymerisation of styrene in a heterogeneous medium. Surface functionalisation was confirmed by infrared spectroscopy, contact angle measurements, and thermogravimetric and elemental analysis. X-ray diffraction and scanning electron microscopy showed that there was no significant change in the morphology or crystallinity of the nanoparticles following ozonolysis. The grafting efficiency, quantified by 13C NMR, was greater for SNC, with a styrene/anhydroglucose ratio of 1.56 compared to 0.25 for CNC. The thermal stability improved by 100 °C. The contact angles were 97° and 78° following the SNC and CNC grafting, respectively, demonstrating the efficiency of the grafting in changing the surface properties even at low levels of surface substitution. The grafting increased the compatibility with the polylactide, and produced nanocomposites with improved water vapour barrier properties. Ozone-mediated grafting is thus a promising approach for surface functionalisation of polysaccharide nanocrystals
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