3,143 research outputs found
Hyperbolic Balance Laws with a Non Local Source
This paper is devoted to hyperbolic systems of balance laws with non local
source terms. The existence, uniqueness and Lipschitz dependence proved here
comprise previous results in the literature and can be applied to physical
models, such as Euler system for a radiating gas and Rosenau regularization of
the Chapman-Enskog expansion.Comment: 26 page
Traps of multi-level governance. Lessons from the implementation of the Water Framework Directive in Italy
During recent decades, different patterns of multi-level governance (MLG) have spread across Europe as a consequence of Europeanisation of public policies, which have increasingly adopted decentralized and participatory procedures conceived as a tool of more effective and accountable policy-making. It appears, however, that the implementation of operational designs based on MLG may be rather problematic and it does not necessarily bring to the expected performance improvements. Referring to the case of the EU Water Framework Directive (2000/60/EC), which conceives the creation of new multi-level institutional settings as a key tool for enacting a new holistic approach to water management and protection, this article explores the difficulties that the implementation of such settings has brought in Italy, despite some favorable pre-conditions existing in the country. Evidence is provided that along with institutional and agency variables, the implementation effectiveness of MLG arrangements promoted by the EU can be challenged by their inherent characteristics
Tensions of Integration in Professional Formation: Investigating Development of Engineering Students\u27 Social and Technical Perceptions
Tensions of Integration in Professional Formation: Investigating Development of Engineering Students\u27 Social and Technical PerceptionsTwenty-first century engineers face incredible challenges and opportunities, many of which aresocially complex, transcending the traditional “technical” boundaries of engineering. Thetechnology produced by engineers must not only function as predicted by mathematical andtheoretical models but must also operate beneficially and seamlessly in complex social contexts.In this sense, engineers must embody an integrated social and technical – or sociotechnical –identity rather than a dualistic social/technical one.A growing body of scholarship has discussed how dominant cultures of engineering shapestudents’ and professionals’ understandings of social and technical dimensions of their work.Further, engineering education research has advanced understanding of how engineering identityis formed by external, structural forces. Yet, from a psychological perspective, we know littleabout how engineering students come to perceive and embody their identities as engineers,especially in relation to social and technical dimensions of these identities. Thus, we organizedthis study around the following research questions.RQ0: How do students psychologically experience identity trajectories of becoming engineers?RQ1: How do students perceive the social and technical features of engineering identity?RQ2: How do students internally experience their identities as engineers, particularly with regard to social and technical dimensions of these identities?RQ3: How do social and technical perceptions of their engineering identity develop and change in the course of the engineering curriculum or in the transition to the workplace?To respond to these research questions, we have conducted two longitudinal studies usinginterpretative phenomenological analysis (IPA). One study focused on graduating seniors as theytransitioned into the workplace, and the second study focused on first-year students transitioningto engineering degree coursework. These investigations produced robust and nuancedunderstanding of students’ engineering identity trajectories throughout and beyond thecurriculum. These findings are being leveraged in order to provide our initial understanding in athematic analysis on sophomore engineering students.Thus far, the findings of the investigation highlight the complexity of becoming both engineers,specifically by demonstrating a somewhat contradictory relationship between what participantsperceived to be engineering and how they actually embodied an engineering-self. They furtherdemonstrate the manifold ways that participants realized and prioritized identities outside ofengineering and how these multiple selves interacted in ways that affected their engineeringidentities. Additionally, findings for both male and female groups suggest that somepsychological patterns might be related to gender. In sum, the findings depict a complex pictureof engineering-students-turned-engineers as whole persons. By focusing on how engineeringidentity development is embodied, the findings generate multiple theoretical insights that bearrelevance for engineering education research and provocative implications that bear significancefor engineering educators, students, and employers
A variational approach to the macroscopic electrodynamics of anisotropic hard superconductors
We consider the Bean's critical state model for anisotropic superconductors.
A variational problem solved by the quasi--static evolution of the internal
magnetic field is obtained as the -limit of functionals arising from
the Maxwell's equations combined with a power law for the dissipation.
Moreover, the quasi--static approximation of the internal electric field is
recovered, using a first order necessary condition. If the sample is a long
cylinder subjected to an axial uniform external field, the macroscopic
electrodynamics is explicitly determined.Comment: 24 pages, 15 figure
Polyakov Lines in Yang-Mills Matrix Models
We study the Polyakov line in Yang-Mills matrix models, which include the
IKKT model of IIB string theory. For the gauge group SU(2) we give the exact
formulae in the form of integral representations which are convenient for
finding the asymptotic behaviour. For the SU(N) bosonic models we prove upper
bounds which decay as a power law at large momentum p. We argue that these
capture the full asymptotic behaviour. We also indicate how to extend the
results to some correlation functions of Polyakov lines.Comment: 19 pages, v2 typos corrected, v3 ref adde
Interleukin-1 plays a major role in vascular inflammation and atherosclerosis in male apolipoprotein E-knockout mice
Objective: To examine the role of the balance between interleukin (IL)-1 and IL-1 receptor antagonist (IL-1Ra) in atherosclerosis and vascular inflammation. Methods: Transgenic (Tg) mice overexpressing either secreted IL-1Ra or intracellular IL-1Ra1 as well as IL-1Ra-deficient mice (IL-1Ra −/−) were crossed with apolipoprotein E-deficient mice (ApoE −/−). Results: In males fed a cholesterol-rich diet for 10 weeks, average atherosclerotic lesion area within aortic roots was significantly decreased in ApoE −/− secreted IL-1Ra Tg (−47%) and ApoE −/− intracellular IL-1Ra1 Tg (−40%) mice as compared to ApoE −/− non-Tg controls. The extent of sudanophilic lesions was reduced within the thoraco-abdominal aorta in ApoE −/− secreted IL-1Ra (−53%) and ApoE −/− intracellular IL-1Ra1 (−67%) Tg mice. In parallel experiments, we observed early mortality and illness among double deficient mice, whereas ApoE −/− IL-1Ra +/+ and ApoE +/+ IL-1Ra −/− mice were apparently healthy. After 7 weeks of diet, ApoE −/− IL-1Ra −/− mice exhibited massive aortic inflammation with destruction of the vascular architecture, but no signs of atherosclerosis. ApoE −/− IL-1Ra +/+ had atherosclerosis and a moderate inflammatory reaction, whereas ApoE +/+ IL-1Ra −/− mice were free of vascular lesions. Macrophages were present in large amounts within inflammatory lesions in the adventitia of ApoE −/− IL-1Ra −/− mice. Conclusion: Our results demonstrate that the IL-1/IL-1Ra ratio plays a critical role in the pathogenic mechanisms leading to vascular inflammation and atherosclerosis in ApoE −/− mic
Yang-Mills Integrals
Two results are presented for reduced Yang-Mills integrals with different
symmetry groups and dimensions: the first is a compact integral representation
in terms of the relevant variables of the integral, the second is a method to
analytically evaluate the integrals in cases of low order. This is exhibited by
evaluating a Yang-Mills integral over real symmetric matrices of order 3.Comment: LaTeX, 10 pages, references added and minimal change
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