263 research outputs found

    Persistence of Diophantine flows for quadratic nearly-integrable Hamiltonians under slowly decaying aperiodic time dependence

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    The aim of this paper is to prove a Kolmogorov-type result for a nearly-integrable Hamiltonian, quadratic in the actions, with an aperiodic time dependence. The existence of a torus with a prefixed Diophantine frequency is shown in the forced system, provided that the perturbation is real-analytic and (exponentially) decaying with time. The advantage consists of the possibility to choose an arbitrarily small decaying coefficient, consistently with the perturbation size.Comment: Several corrections in the proof with respect to the previous version. Main statement unchange

    Normal Form and Nekhoroshev stability for nearly-integrable Hamiltonian systems with unconditionally slow aperiodic time dependence

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    The aim of this paper is to extend the results of Giorgilli and Zehnder for aperiodic time dependent systems to a case of general nearly-integrable convex analytic Hamiltonians. The existence of a normal form and then a stability result are shown in the case of a slow aperiodic time dependence that, under some smallness conditions, is independent on the size of the perturbation.Comment: Corrected typo in the title and statement of Lemma 3.

    A film-forming graphene/diketopyrrolopyrrole covalent hybrid with far-red optical features: Evidence of photo-stability

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    A dianiline derivative of a symmetric donor-acceptor-donor diketopyrrolopyrrole-based dye is employed for the two-sided covalent functionalization of liquid exfoliated few layers graphene flakes, through a direct arylation reaction. The resulting nanohybrid features the properties of a polymeric species, being solution-processed into homogeneous thin films, featuring a pronounced red-shift of the main absorption band with respect to the model dye unit and energy levels comparable to those of common diketopyrrolopyrrole-based polymers. A good electrical conductivity and the absence of radical signals generated after intense white light illumination, as probed through electron paramagnetic resonance, suggest a possible future application of this composite ma- terial in the field of photoprotective, antistatic layers with tunable colors

    The interaction of bacteria with engineered nanostructured polymeric materials : a review

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    Bacterial infections are a leading cause of morbidity and mortality worldwide. In spite of great advances in biomaterials research and development, a significant proportion of medical devices undergo bacterial colonization and become the target of an implant-related infection. We present a review of the two major classes of antibacterial nanostructured materials: polymeric nanocomposites and surface-engineered materials. The paper describes antibacterial effects due to the induced material properties, along with the principles of bacterial adhesion and the biofilm formation process. Methods for antimicrobial modifications of polymers using a nanocomposite approach as well as surface modification procedures are surveyed and discussed, followed by a concise examination of techniques used in estimating bacteria/material interactions. Finally, we present an outline of future sceneries and perspectives on antibacterial applications of nanostructured materials to resist or counteract implant infections

    Why do we need (another) special issue on gender and VET?

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    The Journal of Vocational Education and Training last had a special issue on gender and vocational education and training (VET) in 2006. In the intervening 8 years, the journal has published 264 research papers, of which just 10 - that is, less than 4% - addressed the issue of gender in any substantive way. This is something of a disappointment, as editors always hope that a special issue will provoke increased discussion and debate in the journal about its theme as well as providing a focused resource. Is the problem that, compared to the effects of global labour migration flows, constantly rising youth unemployment figures or emerging skills gaps in an aging society, gender issues have lost their relevance as just one category of social inequalities among many others? This can hardly be the case, since it is obviously a most thorough-going and persistent one. Despite over 30 years of gender studies, and numerous policy initiatives to address gender inequalities, gender segregation persists in VET as well as in the labour market. Women still earn less, hold the majority of part-time contracts, tend to be stereotyped into caring and personal service work, and are largely under-represented in leadership positions. Is the problem then that there is nothing new to be said about gender and VET? We do not agree that that is the case either: gender injustice remains a central issue in VET and the labour market; and as the social, political and economic landscape changes rapidly in today's world, it is inevitable that gender inequalities are produced and reproduced in new and different ways. So we felt the need to call once again for a collection of papers dedicated specifically to this topic, and one that would reflect this evolution

    Affective economies, pandas, and the atmospheric politics of lively capital

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    This paper is concerned with the affective economies of lively capital. Its central argument is that nonhuman life itself has become a locus of accumulation, marked by an atmospheric politics of capital: the intensification of relations between life and productivity by incorporating entire lifeworlds into regimes of generating value. Focusing on the Giant panda – a spectacular icon raising millions of dollars globally – the paper first examines junctures at which their charismatic affects emerge and are manipulated to produce value. Turning to panda lifeworlds in zoos, it then shows how such value production is contingent upon affective labours nonhumans perform in captivity. Nonhuman labour, as a component of atmospheric politics, enables understanding how lively capital is produced and reproduced, a theme interrogated through a critical analysis of the commercial global circulation of pandas. The paper develops the concept of atmospheric politics – an intervention in an animal’s milieu and its affective intensities – as a means for analyzing the dynamics of lively capital. Atmospheric politics retrieves a critical political economy obscured by the concept of nonhuman charisma, and restages biopower as an apparatus and political technology of capital.Parts of the research conducted for this paper was enabled by a British Academy Postdoctoral Fellowship (Award No. pf140038)

    Neutrophil Paralysis in Plasmodium vivax Malaria

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    Plasmodium vivax is responsible for approximately 60–80% of the malaria cases in the world, and contributes to significant social and economic instability in the developing countries of Latin America and Asia. The pathogenesis of P. vivax malaria is a consequence of host derived inflammatory mediators. Hence, a better understanding of the mechanisms involved in induction of systemic inflammation during P. vivax malaria is critical for the clinical management and prevention of severe disease. The innate immune receptors recognize Plasmodium sp. and initiate a broad spectrum of host defense mechanisms that mediate resistance to infection. However, the innate immune response is the classic “two-edged sword”, and clinical malaria is associated with high levels of circulating pro-inflammatory cytokines. Our findings show that both monocytes and neutrophils are highly activated during malaria. Monocytes produced high levels of IL-1β, IL-6 and TNF-α during acute malaria. On the other hand, neutrophils were a poor source of cytokines, but displayed an enhanced phagocytic activity and superoxide production. Unexpectedly, we noticed an impaired chemotaxis of neutrophils towards an IL-8 (CXCL8) gradient. We proposed that neutrophil paralysis is in part responsible for the enhanced susceptibility to bacterial infection observed in malaria patients

    Mobile Phones and Social Signal Processing for Analysis and Understanding of Dyadic Conversations

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    Social Signal Processing is the domain aimed at bridging the social intelligence gap between humans and machines via modeling, analysis and synthesis of nonverbal behavior in social interactions. One of the main challenges of the domain is to sense unobtrusively the behavior of social interaction participants, one of the key conditions to preserve the spontaneity and naturalness of the interactions under exam. In this respect, mobile devices offer a major opportunity because they are equipped with a wide array of sensors that, while capturing the behavior of their users with an unprecedented depth, are still invisible. This is particularly important because mobile devices are part of the everyday life of a large number of individuals and, hence, they can be used to investigate and sense natural and spontaneous scenarios
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