986 research outputs found
Initiating e-learning by stealth, participation and consultation in a late majority institution
The extent to which opportunities afforded by e-learning are embraced by an institution can depend in large measure on whether it is perceived as enabling and transformative or as a major and disruptive distraction. Most case studies focus on the former. This paper describes how e-learning was introduced into the latter environment. The sensitivity of competing pressures in a research intensive university substantially influenced the manner in which e-learning was promoted. This paper tells that story, from initial stealth to eventual university acknowledgement of the relevance of e-learning specifically to its own context
Constructing Hybrid Baryons with Flux Tubes
Hybrid baryon states are described in quark potential models as having
explicit excitation of the gluon degrees of freedom. Such states are described
in a model motivated by the strong coupling limit of Hamiltonian lattice gauge
theory, where three flux tubes meeting at a junction play the role of the glue.
The adiabatic approximation for the quark motion is used, and the flux tubes
and junction are modeled by beads which are attracted to each other and the
quarks by a linear potential, and vibrate in various string modes. Quantum
numbers and estimates of the energies of the lightest hybrid baryons are
provided.Comment: 4 pages, RevTeX. Submitted to Physical Review Letter
The central role of DNA damage in immunosenescence
Ageing is the biggest risk factor for the development of multiple chronic diseases as well as increased infection susceptibility and severity of diseases such as influenza and COVID-19. This increased disease risk is linked to changes in immune function during ageing termed immunosenescence. Age-related loss of immune function, particularly in adaptive responses against pathogens and immunosurveillance against cancer, is accompanied by a paradoxical gain of function of some aspects of immunity such as elevated inflammation and increased incidence of autoimmunity. Of the many factors that contribute to immunosenescence, DNA damage is emerging as a key candidate. In this review, we discuss the evidence supporting the hypothesis that DNA damage may be a central driver of immunosenescence through senescence of both immune cells and cells of non-haematopoietic lineages. We explore why DNA damage accumulates during ageing in a major cell type, T cells, and how this may drive age-related immune dysfunction. We further propose that existing immunosenescence interventions may act, at least in part, by mitigating DNA damage and restoring DNA repair processes (which we term “genoprotection”). As such, we propose additional treatments on the basis of their evidence for genoprotection, and further suggest that this approach may provide a viable therapeutic strategy for improving immunity in older people
The Influence of Coalition Formation on Idea Selection in Dispersed Teams: A Game Theoretic Approach
Sie, R. L. L., Bitter-Rijpkema, M., & Sloep, P. B. (2009). The Influence of Coalition Formation on Idea Selection in Dispersed Teams: A Game Theoretic Approach. In U. Cress, V. Dimitrova & M. Specht (Eds.), Learning in the Synergy of Multiple Disciplines. Proceedings of the Fourth European Conference on Technology-Enhanced Learning (EC-TEL 2009) (pp. 732-737). September, 29 - October, 2, 2009, Nice, France. Lecture Notes in Computer Science Vol. 5794. Berlin: Springer-Verlag.In an open innovation environment, organizational learning takes place by means of dispersed teams which expand their knowledge through collaborative idea generation. Research is often focused on finding ways to extend the set of ideas, while the main problem in our opinion is not the number of ideas that is generated, but a non-optimal set of ideas accepted during idea selection. When selecting ideas, coalitions form and their composition may influence the resulting set of accepted ideas. We expect that computing coalitional strength during idea selection will help in forming the right teams to have a grand coalition, or having a better allocation of accepted ideas, or neutralising factors that adversely influence the decision making process. Based on a literature survey, this paper proposes the application of the Shapley value and the nucleolus to compute coalitional strength in order to enhance the group decision making process during collaborative idea selection. This document does not represent the opinion of the European Union, and the European Union is not responsible for any use that might be made of its content.The idSpace project is partially supported/co-funded by the European Union under the Information and Communication Technologies (ICT) theme of the 7th Framework Programme for R&
Decay Properties of the Connectivity for Mixed Long Range Percolation Models on
In this short note we consider mixed short-long range independent bond
percolation models on . Let be the probability that the edge
will be open. Allowing a -dependent length scale and using a
multi-scale analysis due to Aizenman and Newman, we show that the long distance
behavior of the connectivity is governed by the probability
. The result holds up to the critical point.Comment: 6 page
Nonlinear porous medium flow with fractional potential pressure
We study a porous medium equation, with nonlocal diffusion effects given by
an inverse fractional Laplacian operator. We pose the problem in n-dimensional
space for all t>0 with bounded and compactly supported initial data, and prove
existence of a weak and bounded solution that propagates with finite speed, a
property that is nor shared by other fractional diffusion models.Comment: 32 pages, Late
Analysis of path integrals at low temperature : Box formula, occupation time and ergodic approximation
We study the low temperature behaviour of path integrals for a simple
one-dimensional model. Starting from the Feynman-Kac formula, we derive a new
functional representation of the density matrix at finite temperature, in terms
of the occupation times of Brownian motions constrained to stay within boxes
with finite sizes. From that representation, we infer a kind of ergodic
approximation, which only involves double ordinary integrals. As shown by its
applications to different confining potentials, the ergodic approximation turns
out to be quite efficient, especially in the low-temperature regime where other
usual approximations fail
Modelling the impact of school reopening and contact tracing strategies on Covid-19 dynamics in different epidemiologic settings in Brazil
This study was funded by the Brazilian National Council for Scientific and Technological Development (CNPq) [grant number 402834/2020-8]. MEB received a technological and industrial scholarship from CNPq [grant number 315854/2020-0]. LSF received a master's scholarship from Coordination for the Improvement of Higher Education Personnel (CAPES) [finance code 001]. SP was supported by São Paulo Research Foundation (FAPESP) [grant number 2018/24037-4]. AMB received a technological and industrial scholarship from CNPq [grant number 402834/2020-8]. CF was supported by FAPESP [grant numbers 2019/26310-2 and 2017/26770-8]. MQMR received a postdoctoral scholarship from CAPES [grant number 305269/2020-8]. LMS received a technological and industrial scholarship from CNPq [grant number 315866/2020-9]. RSK has been supported by CNPq [grant number 312378/2019-0]. PIP has been supported by CNPq [grant number 313055/2020-3]. JAFD-F has been supported by CNPq productivity fellowship and the National Institutes for Science and Technology in Ecology, Evolution and Biodiversity Conservation (INCT-EEC), supported by MCTIC/CNPq [grant number 465610/2014-5] and Goiás Research Foundation (FAPEG) [grant number 201810267000023]. RAK has been supported by CNPq [grant number 311832/2017-2] and FAPESP [grant number 2016/01343-7]. CMT has been supported by CNPq productivity fellowship and the National Institute for Health Technology Assessment (IATS) [grant number 465518/2014-1].Peer reviewedPublisher PD
Coulomb effects in granular materials at not very low temperatures
We consider effects of Coulomb interaction in a granular normal metal at not
very low temperatures suppressing weak localization effects. In this limit
calculations with the initial electron Hamiltonian are reduced to integrations
over a phase variable with an effective action, which can be considered as a
bosonization for the granular metal. Conditions of the applicability of the
effective action are considered in detail and importance of winding numbers for
the phase variables is emphasized. Explicit calculations are carried out for
the conductivity and the tunneling density of states in the limits of large
and small tunnelling conductances. It is demonstrated for any
dimension of the array of the grains that at small the conductivity and the
tunnelling density of states decay with temperature exponentially. At large
the conductivity also decays with decreasing the temparature and its
temperature dependence is logarithmic independent of dimensionality and
presence of a magnetic field. The tunnelling density of states for is
anomalous in any dimension but the anomaly is stronger than logarithmic in low
dimensions and is similar to that for disordered systems. The formulae derived
are compared with existing experiments. The logarithmic behavior of the
conductivity at large obtained in our model can explain numerous
experiments on systems with a granular structure including some high
materials.Comment: 30 page
Local well-posedness for membranes in the light cone gauge
In this paper we consider the classical initial value problem for the bosonic
membrane in light cone gauge. A Hamiltonian reduction gives a system with one
constraint, the area preserving constraint. The Hamiltonian evolution equations
corresponding to this system, however, fail to be hyperbolic. Making use of the
area preserving constraint, an equivalent system of evolution equations is
found, which is hyperbolic and has a well-posed initial value problem. We are
thus able to solve the initial value problem for the Hamiltonian evolution
equations by means of this equivalent system. We furthermore obtain a blowup
criterion for the membrane evolution equations, and show, making use of the
constraint, that one may achieve improved regularity estimates.Comment: 29 page
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