770 research outputs found

    On a class of polynomial Lagrangians

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    In the framework of finite order variational sequences a new class of Lagrangians arises, namely, \emph{special} Lagrangians. These Lagrangians are the horizontalization of forms on a jet space of lower order. We describe their properties together with properties of related objects, such as Poincar\'e--Cartan and Euler--Lagrange forms, momenta and momenta of generating forms, a new geometric object arising in variational sequences. Finally, we provide a simple but important example of special Lagrangian, namely the Hilbert--Einstein Lagrangian.Comment: LaTeX2e, amsmath, diagrams, hyperref; 15 page

    The Prolongation Problem for the Heavenly Equation

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    We provide an exact regular solution of an operator system arising as the prolongation structure associated with the heavenly equation. This solution is expressed in terms of operator Bessel coefficients.Comment: 9 pages, Proc. SIGRAV Conference (Bari 1998

    On the Lyapunov function for the rotating BĂ©nard problem

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    In this paper we study the nonlinear Lyapunov stability of the conduction-diffusion solution in a layer of a rotating Newtonian fluid, heated and salted from below. If we reformulate the nonlinear stability problem, projecting the initial perturbation evolution equations on some suitable orthogonal subspaces, we preserve the contribution of the Coriolis term, and jointly all the nonlinear terms vanish. We prove that, if the principle of exchange of stabilities holds, the linear and nonlinear stability bounds are equal. We find that the nonlinear stability bound is nothing else but the critical Rayleigh number obtained solving the linear instability proble

    Integrable nonlinear field equations and loop algebra structures

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    We apply the (direct and inverse) prolongation method to a couple of nonlinear Schr{\"o}dinger equations. These are taken as a laboratory field model for analyzing the existence of a connection between the integrability property and loop algebras. Exploiting a realization of the Kac-Moody type of the incomplete prolongation algebra associated with the system under consideration, we develop a procedure with allows us to generate a new class of integrable nonlinear field equations containing the original ones as a special case.Comment: 13 pages, latex, no figures

    Inactive Residents Living in Nursing Homes and Associated Predictors: Findings From a Regional-Based, Italian Retrospective Study.

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    Objectives: It has been amply reported that nursing home (NH) residents are largely inactive, a condition that may further increase functional decline, behavioral disorders, and risk of death. To date, studies have mainly focused on individual characteristics that may decrease residents' involvement in activities. Therefore, the aim of this study is to describe the prevalence of inactive NH residents in an Italian context, identifying predictors of inactivity at the individual and NH levels. Design: Retrospective regional-based study performed in 2014. Setting: All NHs (n = 105) located in the Friuli Venezia Giulia Region, northeastern region of Italy. Participants: A total of 8875 residents with at least 1 nursing assessment and living in an NH for at least 1 year. Measurements: The dependent variable was inactivity in the last week, defined as the resident not being involved in any socially or individually based, or meaningful recreational (eg, gardening) activities. The independent variables were set at individual and NH levels. Aiming at identifying predictors of inactivity, a hierarchical generalized linear (mixed-effects) model incorporating both fixed-effect parameters and random effects, was performed. Results: A total of 4042 (45.6%) residents were inactive during the week before the evaluation. At the resident level, those with severe cognitive impairment [odds (OR) 4.462, 95% confidence interval (CI) 3.880-5.132], unsociable behavior (OR 2.961, 95% CI 2.522-3.473), night restlessness (OR 1.605, 95% CI 1.395-1.853), lack of cooperation in daily care (OR 1.408, 95% CI 1.199-1.643), pressure sores (OR 1.314, 95% CI 1.065-1.622), depressive disorders (OR 1.242, 95% CI 1.089-1.416), and clinical instability (OR 1.110, 95% CI 1.037-1.188) reported an increased risk of being inactive. At the NH level, for each additional hour of care offered by professional educators, there was 1% less likelihood of inactive residents (OR .964, 95% .933-.996). Conclusions: Approximately one-half of the residents in this study living in Italian NHs are inactive. Inactivity is significantly associated with the presence of severe cognitive impairment, behavioral disorders (eg, unsociability, night restlessness, and lack of cooperation in daily care), pressure sores, depressive symptoms, and clinical instability. Moreover, receiving care from professional educators whose aim in their training program and professional mission is to improve individual and social engagement, decreased the likelihood of resident inactivity. \ua9 2016 AMDA - The Society for Post-Acute and Long-Term Care Medicine

    Chemical, biochemical and microbiological properties of soils from abandoned and extensively cultivated olive orchards

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    The abandonment of olive orchards is a phenomenon of great importance triggered mainly by economic and social causes. The aim of this study was to investigate some chemical, biochemical and microbiological properties in a soil of a Southern olive grove abandoned since 25 years. In order to define the effect of the long-term land abandonment on soil properties, an adjacent olive grove managed according to extensive practices was taken as reference (essentially minimum tillage and no fertilization). Soil organic matter, total nitrogen and pH were significantly higher in the abandoned olive grove due to the absence of tillage and the natural inputs of organic matter at high C/N ratio which, inter alia, increased the number of cellulolytic bacteria and stimulated the activity of β-glucosidase, an indicator of a more advanced stage of soil evolution. The soil of the abandoned olive orchard showed a lower number of total bacteria and fungi and a lower microbial diversity, measured by means of the Biolog® method, as a result of a sort of specialization trend towards low quality organic substrates. From this point of view, the extensive cultivation management seemed to not induce a disturbance to microbiological communities

    Cryotomography of budding influenza a virus reveals filaments with diverse morphologies that mostly do not bear a genome at their distal end

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    Influenza viruses exhibit striking variations in particle morphology between strains. Clinical isolates of influenza A virus have been shown to produce long filamentous particles while laboratory-adapted strains are predominantly spherical. However, the role of the filamentous phenotype in the influenza virus infectious cycle remains undetermined. We used cryo-electron tomography to conduct the first three-dimensional study of filamentous virus ultrastructure in particles budding from infected cells. Filaments were often longer than 10 microns and sometimes had bulbous heads at their leading ends, some of which contained tubules we attribute to M1 while none had recognisable ribonucleoprotein (RNP) and hence genome segments. Long filaments that did not have bulbs were infrequently seen to bear an ordered complement of RNPs at their distal ends. Imaging of purified virus also revealed diverse filament morphologies; short rods (bacilliform virions) and longer filaments. Bacilliform virions contained an ordered complement of RNPs while longer filamentous particles were narrower and mostly appeared to lack this feature, but often contained fibrillar material along their entire length. The important ultrastructural differences between these diverse classes of particles raise the possibility of distinct morphogenetic pathways and functions during the infectious process

    UniPR1331: small Eph/ephrin antagonist beneficial in intestinal inflammation by interfering with type-B signaling

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    Eph receptors, comprising A and B classes, interact with cell-bound ephrins generating bidirectional signaling. Although mainly related to carcinogenesis and organogenesis, the role of Eph/ephrin system in inflammation is growingly acknowledged. Recently, we showed that EphA/ephrin-A proteins can modulate the acute inflammatory responses induced by mesenteric ischemia/reperfusion, while beneficial effects were granted by EphB4, acting as EphB/ephrin-B antagonist, in a murine model of Crohn’s disease (CD). Accordingly, we now aim to evaluate the effects of UniPR1331, a pan-Eph/ephrin antagonist, in TNBS-induced colitis and to ascertain whether UniPR1331 effects can be attributed to A- or B-type signaling interference. The potential anti-inflammatory action of UniPR1331 was compared to those of the recombinant proteins EphA2, a purported EphA/ephrin-A antagonist, and of ephrin-A1-Fc and EphA2-Fc, supposedly activating forward and reverse EphA/ephrin-A signaling, in murine TNBS-induced colitis and in stimulated cultured mononuclear splenocytes. UniPR1331 antagonized the inflammatory responses both in vivo, mimicking EphB4 protection, and in vitro; EphA/ephrin-A proteins were inactive or only weakly effective. Our findings represent a further proof-of-concept that blockade of EphB/ephrin-B signaling is a promising pharmacological strategy for CD management and highlight UniPR1331 as a novel drug candidate, seemingly working through the modulation of immune responses
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