2,517 research outputs found
Probabilistic reconstruction of genealogies for polyploid plant species
A probabilistic reconstruction of genealogies in a polyploid population (from 2x to 4x) is investigated, by considering genetic data analyzed as the probability of allele presence in a given genotype. Based on the likelihood of all possible crossbreeding patterns, our model enables to infer and to quantify the whole potential genealogies in the population. We explain in particular how to deal with the uncertain allelic multiplicity that may occur with polyploids. Then we build an ad hoc penalized likelihood to compare genealogies and to decide whether a particular individual brings a sufficient information to be included in the taken genealogy. This decision criterion enables us in a next part to suggest a greedy algorithm in order to explore missing links and to rebuild some connections in the genealogies, retrospectively. As a by-product, we also give a way to infer the individuals that may have been favored by breeders over the years. In the last part we highlight the results given by our model and our algorithm, firstly on a simulated population and then on a real population of rose bushes. Most of the methodology relies on the maximum likelihood principle and on the graph theory
Charitable Immunity from Tort Liability in Ohio: Present Status and Future Prospects
International audienc
Sharing data through confidential clouds: an architectural perspective
© 2015 IEEE.Cloud and mobile are two major computing paradigms that are rapidly converging. However, these models still lack a way to manage the dissemination and control of personal and business-related data. To this end, we propose a framework to control the sharing, dissemination and usage of data based on mutually agreed Data Sharing Agreements (DSAs). These agreements are enforced uniformly, and end-to-end, both on Cloud and mobile platforms, and may reflect legal, contractual or user-defined preferences. We introduce an abstraction layer that makes available the enforcement functionality across different types of nodes whilst hiding the distribution of components and platform specifics. We also discuss a set of different types of nodes that may run such a layer
The emergence of quantum capacitance in epitaxial graphene
We found an intrinsic redistribution of charge arises between epitaxial
graphene, which has intrinsically n-type doping, and an undoped substrate. In
particular, we studied in detail epitaxial graphene layers thermally elaborated
on C-terminated - (- ()). We have investigated
the charge distribution in graphene-substrate systems using Raman spectroscopy.
The influence of the substrate plasmons on the longitudinal optical phonons of
the substrates has been detected. The associated charge redistribution
reveals the formation of a capacitance between the graphene and the substrate.
Thus, we give for the first time direct evidence that the excess negative
charge in epitaxial monolayer graphene could be self-compensated by the
substrate without initial doping. This induced a previously unseen
redistribution of the charge-carrier density at the substrate-graphene
interface. There a quantum capacitor appears, without resorting to any
intentional external doping, as is fundamentally required for epitaxial
graphene. Although we have determined the electric field existing inside the
capacitor and revealed the presence of a minigap () for
epitaxial graphene on - face terminated carbon, it remains small in
comparison to that obtained for graphene on face terminated . The
fundamental electronic properties found here in graphene on substrates
may be important for developing the next generation of quantum technologies and
electronic/plasmonic devices.Comment: 26 pages, 8 figures, available online as uncorrected proof, Journal
of Materials Chemistry C (2016
Theoretical and experimental study of the orientational ordering in the field-induced intermediaite phase from the SmC*FI2 phase in chiral smectic liquid crystals
Under an electric field, chiral smectic liquid crystals transit usually to
the unwound SmC* phase where the helical structure is completely unrolled.
Sometimes the sample transits initially towards an intermediate polar state
before the total destruction of the helix. Based on the extension of the H-T
model, a theoretical study of these field-induced phase transitions was carried
out. Two hypotheses of the dynamics that give rise to the appearance of the
intermediate phase have been discussed. The results of a numerical analysis
confirm the known experimental results; the intermediate phase has a
three-layer periodicity structure
La métaplasie malpighienne dans le carcinome papillaire de la thyroïde
Introduction : la métaplasie malpighienne est rare au niveau de la thyroïde. Elle peut être associée à un processus pathologique tumoral ou inflammatoire.Matériels et méthodes : les auteurs se proposent de rapporter une observation de métaplasie malpighienne de la thyroïde associée à un carcinome papillaire diagnostiqué au service d’Anatomie et de Cytologie pathologiques du CHU Farhat Hached de Sousse et d’en discuter la pathogénie de cette métaplasie, ses circonstances de survenue et ses difficultés diagnostiques.Résultats : il s’agissait d’une fille âgée de 9 ans ayant consulté pour un nodule de la thyroïde. Une cytoponction de ce nodule était pratiquée et avait montré la présence de cellules tumorales d’un carcinome papillaire. Une thyroïdectomie totale avec curage triangulaire fonctionnel a été réalisée. L’examen anatomo-pathologique de la pièce a confirmé la présence d’un carcinome papillaire de la thyroïde avec présence au voisinage de la tumeur de plages de cellules malpighiennes d’allure non tumorale.Conclusion : bien que rare, la métaplasie malpighienne peut se voir dans la thyroïde. Elle doit être distinguée d’un carcinome épidermoïde de la thyroïde par la recherche systématique, devant tout foyer de métaplasie malpighienne, des signes de malignité.Mots clés : métaplasie malpighienne, carcinome papillaire, glande thyroïde
Faster Algorithms for All-Pairs Bounded Min-Cuts
The All-Pairs Min-Cut problem (aka All-Pairs Max-Flow) asks to compute a minimum s-t cut (or just its value) for all pairs of vertices s,t. We study this problem in directed graphs with unit edge/vertex capacities (corresponding to edge/vertex connectivity). Our focus is on the k-bounded case, where the algorithm has to find all pairs with min-cut value less than k, and report only those. The most basic case k=1 is the Transitive Closure (TC) problem, which can be solved in graphs with n vertices and m edges in time O(mn) combinatorially, and in time O(n^{omega}) where omega<2.38 is the matrix-multiplication exponent. These time bounds are conjectured to be optimal.
We present new algorithms and conditional lower bounds that advance the frontier for larger k, as follows:
- A randomized algorithm for vertex capacities that runs in time {O}((nk)^{omega}). This is only a factor k^omega away from the TC bound, and nearly matches it for all k=n^{o(1)}.
- Two deterministic algorithms for edge capacities (which is more general) that work in DAGs and further reports a minimum cut for each pair. The first algorithm is combinatorial (does not involve matrix multiplication) and runs in time {O}(2^{{O}(k^2)}* mn). The second algorithm can be faster on dense DAGs and runs in time {O}((k log n)^{4^{k+o(k)}}* n^{omega}). Previously, Georgiadis et al. [ICALP 2017], could match the TC bound (up to n^{o(1)} factors) only when k=2, and now our two algorithms match it for all k=o(sqrt{log n}) and k=o(log log n).
- The first super-cubic lower bound of n^{omega-1-o(1)} k^2 time under the 4-Clique conjecture, which holds even in the simplest case of DAGs with unit vertex capacities. It improves on the previous (SETH-based) lower bounds even in the unbounded setting k=n. For combinatorial algorithms, our reduction implies an n^{2-o(1)} k^2 conditional lower bound. Thus, we identify new settings where the complexity of the problem is (conditionally) higher than that of TC.
Our three sets of results are obtained via different techniques. The first one adapts the network coding method of Cheung, Lau, and Leung [SICOMP 2013] to vertex-capacitated digraphs. The second set exploits new insights on the structure of latest cuts together with suitable algebraic tools. The lower bounds arise from a novel reduction of a different structure than the SETH-based constructions
La baisse de la densité osseuse au cours des maladies inflammatoires chroniques de l’intestin : prévalence et facteurs de risqué
Introduction: La baisse de la densité minérale osseuse représente la principale manifestation osseuse décrite au cours des maladies inflammatoires chroniques de l'intestin. En Tunisie, très peu d'études ont rapportés sa prévalence et ses facteurs de risque. Le but de ce travail était de déterminer la prévalence de la perte osseuse au cours des maladies inflammatoires chroniques de l'intestin, et rechercher ses facteurs de risque. Méthodes: Patients et méthodes: étude ouverte transversale, réalisée de 2007 jusqu'à 2012. Résultats: 146 cas étaient colligés, dont 105 avaient une maladie de Crohn (71,9%) et 41 avaient une rectocolite hémorragique (28,1%). Il s'agissait de 62 hommes et 84 femmes. L'âge moyen était de 33,18 ans. La perte osseuse était trouvée chez 85 patients (58,2%). Il s'agissait d'une ostéopénie dans 57 cas et d'ostéoporose dans 28 cas. Les facteurs de risque de perte osseuse étaient une activité physique limitée (p=0,013), un indice de masse corporel '20 kg/m2 (p=0,015), une maladie active (p=0,035), l'étendue de l'atteinte intestinale (p=0,006) et une dose cumulée de corticothérapie dépassant 4,5g de Prednisone (p=0,003). Conclusion: La déminéralisation osseuse est une complication fréquente mais non constante. Ceci justifie un dépistage précoce chez les patients à risque, qui pourront ainsi bénéficier d'un traitement substitutif.Key words: Maladie de Crohn, recto-colite hémorragique, densité minérale osseuse, ostéopénie, ostéoporos
Mucormycose Otocerebrale: À Propos D\'un Cas
La mucormycose est une affection mycosique rare mais souvent fatale, survenant sur des terrains débilités. Elle est due à la prolifération de champignons cosmopolites de la famille de mucorales. Elle entraîne des lésions délabrantes et extensives des parties molles avec risque de thromboses vasculaires. Observation : nous rapportons l\'observation d\'une petite fille, âgée de 3 ans , issue d\'un mariage consanguin, hypotrophe, hospitalisée pour otite externe évoluant depuis 3 semaines. La patiente a bénéficié d\'une antromastoidectomie et a été mise sous antibiotiques. Devant une aggravation de l\'état local, avec extension de la nécrose et destruction du conduit auditif externe, une infection
mycosique est fortement suspectée, sur un terrain particulier de déficit immunitaire probable. L\'examen parasitologique d\'un prélèvement local a mis en évidence la présence de filaments mycéliens dont la culture a isolé un Rhizopus oryzae, confirmé aussi par l\'étude anatomopathologique. L\'exploration de l\'immunité a mis en évidence un déficit de l\'immunitaire céllulaire.Un traitement par amphotéricine B était mal toléré (choc anaphylactique), l\'évolution spontanée était rapidement défavorable avec une extension locorégionale importante et une thrombophlébite du sinus latéral homolatéral,
aboutissement au décés. Conclusion : la localisation oto cérebrale de la mucormycose est exeptionnelle, on doit y penser devant une otite externe maligne sur un terrain particulier. La prise en charge doit être urgente afin d\'augmenter les chances de survie.Mucormycosis is a relatively rare, potentially life-threatening, fungal infection. It occurs predominately in immunocompromised hosts.
Vascular invasion, thrombosis and rapid ischemic necrosis of infected tissue are the most characteristic features of this pathology. Early diagnosis and consequently effective treatment are needed to save life in this fatal condition. Report: We report a case of otocerebral mucormycosis occurring in an hypotrophic 3-years old girl suffering from language retardation and chronic diarrhea. Immune system\'s exploration revealed a profound cell-mediated immunity defect. The diagnosis was suspected because of the rapidly extensive necrosis of the external ear conduct, the existence of lateral sinus
thrombosis and the resistance to an aggressive antibiotic therapy.The diagnosis was confirmed by identifying Rhizopus oryzae by pathological examination of the necrotic tissue.
Treatment by intravenous amphotericin B was certainly lately begun and unfortunately complicated by anaphylactic shock. Because no alternative drug was possible, such as liposomal amphotericin B, the girl rapidly died. Conclusion: Otocerebral mucormycosis is extremely rare.It must be considered when ear lesions are necrotic and rapidly extensive
mainly in patients with predisposing conditions. Successful treatment requires tissue excision and early injection of amphotericin B, preferably in its liposomal presentation. Journal Tunisien d\'ORL et de chirurgie cervico-faciale Vol. 16 2006: pp. 42-4
Liposarcoma of the extremities: MR imaging features and their correlation with pathologic data
SummaryObjectiveTo describe the MRI features of liposarcomas of the extremities and correlate them with data from the histologic subtypes.Material and methodsRetrospective study of 20 cases of liposarcoma of the extremities identified on MRI, surgically removed and confirmed at pathology. On MRI examination, T1- and T2-weighted fat-suppressed and non-fat-suppressed images were acquired then gadolinium-enhanced fat-suppressed T1-weighted images were obtained in at least two orthogonal planes.ResultsSixteen female and four male patients aged 12 to 77 years old at presentation, in 16 cases, with a slowly enlarging painless mass (demonstrating no associated local or general inflammatory components), located in the lower extremity (16 cases) and predominantly located in the thigh (13 cases). Pathologic examination revealed three cases of well-differentiated liposarcoma, 12 cases of myxoid liposarcoma one of which with round cells, three cases of pleomorphic liposarcoma, one case of dedifferentiated liposarcoma and one case of mixed-type liposarcoma. MR images mostly showed well-circumscribed tumors (19 cases) . Well-differentiated liposarcomas typically demonstrated a very specific diagnostic appearance as a predominantly adipose mass containing nonlipomatous components seen as thick septa that may show nodularity. Other subtypes of liposarcoma demonstrated a small amount of adipose tissue thus producing a marbled textural pattern on T1-weighted images particularly in myxoid liposarcomas (9 cases), or even nonlipomatous elements in high-grade liposarcomas (in round cell liposarcoma and in two out of three pleomorphic liposarcomas). The myxoid subtype has also a relatively characteristic appearance as a low signal intensity noted on T1-weighted images and a marked high signal intensity on T2. The dedifferentiated liposarcoma has a very specific radiologic appearance as a nonlipomatous component within a predominantly adipose mass, simulating that of well-differentiated liposarcomas.ConclusionMRI of extremity liposarcomas is a highly reliable and sensitive method to characterize liposarcomas. Besides its value in the diagnosis of liposarcoma and locoregional extension control, it allows proper identification of the specific histologic subtypes of liposarcoma.Level of evidenceLevel IV. Rétrospective diagnostic study
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