37,663 research outputs found
Localized and extended states in a disordered trap
We study Anderson localization in a disordered potential combined with an
inhomogeneous trap. We show that the spectrum displays both localized and
extended states, which coexist at intermediate energies. In the region of
coexistence, we find that the extended states result from confinement by the
trap and are weakly affected by the disorder. Conversely, the localized states
correspond to eigenstates of the disordered potential, which are only affected
by the trap via an inhomogeneous energy shift. These results are relevant to
disordered quantum gases and we propose a realistic scheme to observe the
coexistence of localized and extended states in these systems.Comment: Published versio
Strategic Project Organizing
Strategic Project Organizing takes a unique approach to project management that places emphasis on the strategic and organizational aspects of projects and their leadership. Structured around the Three Domains model, it covers all the fundamental project management concepts, whilst guiding the reader through the organizational challenges of enabling positive change.
Through the lens of strategic leadership, this text equips students to know how to respond proactively to threats, as well as seize opportunities, in order to advantageously change the socio-economic environment in an organization's favour. The text also helps students to understand the tools and techniques adopted during the process of organizational transformation.
All chapters offer review and discussion-based questions to encourage critical thinking; as well as case vignettes and a longer, end-of-chapter case study to help students apply theory to practice. Real life projects featured in the case studies include the Eden Project, the Thames Tideway Tunnel and the Berlin Brandenburg Airport
Preliminary notes on the population structure of Heterobasidion abietinum from Abies pinsapo in Spain
Cosmological evolution of warm dark matter fluctuations II: Solution from small to large scales and keV sterile neutrinos
We solve the cosmological evolution of warm dark matter (WDM) density
fluctuations with the Volterra integral equations of paper I. In the absence of
neutrinos, the anisotropic stress vanishes and the Volterra equations reduce to
a single integral equation. We solve numerically this equation both for DM
fermions decoupling at equilibrium and DM sterile neutrinos decoupling out of
equilibrium. We give the exact analytic solution for the density fluctuations
and gravitational potential at zero wavenumber. We compute the density contrast
as a function of the scale factor a for a wide range of wavenumbers k. At fixed
a, the density contrast grows with k for k
k_c, (k_c ~ 1.6/Mpc). The density contrast depends on k and a mainly through
the product k a exhibiting a self-similar behavior. Our numerical density
contrast for small k gently approaches our analytic solution for k = 0. For
fixed k < 1/(60 kpc), the density contrast generically grows with a while for k
> 1/(60 kpc) it exhibits oscillations since the RD era which become stronger as
k grows. We compute the transfer function of the density contrast for thermal
fermions and for sterile neutrinos in: a) the Dodelson-Widrow (DW) model and b)
in a model with sterile neutrinos produced by a scalar particle decay. The
transfer function grows with k for small k and then decreases after reaching a
maximum at k = k_c reflecting the time evolution of the density contrast. The
integral kernels in the Volterra equations are nonlocal in time and their
falloff determine the memory of the past evolution since decoupling. This
falloff is faster when DM decouples at equilibrium than when it decouples out
of equilibrium. Although neutrinos and photons can be neglected in the MD era,
they contribute in the MD era through their memory from the RD era.Comment: 27 pages, 6 figures. To appear in Phys Rev
An investigation into the perspectives of providers and learners on MOOC accessibility
An effective open eLearning environment should consider the target learner’s abilities, learning goals, where learning takes place, and which specific device(s) the learner uses. MOOC platforms struggle to take these factors into account and typically are not accessible, inhibiting access to environments that are intended to be open to all. A series of research initiatives are described that are intended to benefit MOOC providers in achieving greater accessibility and disabled learners to improve their lifelong learning and re-skilling. In this paper, we first outline the rationale, the research questions, and the methodology. The research approach includes interviews, online surveys and a MOOC accessibility audit; we also include factors such the risk management of the research programme and ethical considerations when conducting research with vulnerable learners. Preliminary results are presented from interviews with providers and experts and from analysis of surveys of learners. Finally, we outline the future research opportunities. This paper is framed within the context of the Doctoral Consortium organised at the TEEM'17 conference
How can Multi-Professional Education Support Better Stewardship?
Antimicrobial stewardship is widely accepted as an efficient strategy to combat the growing threat of antimicrobial resistance. Education is one of the cornerstones of successful antimicrobial stewardship programs. There is also general agreement that antimicrobial stewardship is a team effort that must involve the whole continuum of healthcare workers. Providing adequate education for all different professionals although challenging is deemed crucial to achieve good results. This paper reviews the different strategies available to educate the multiple healthcare workers, discusses how education can improve antimicrobial stewardship programs and outlines some of the challenges faced and research gaps that need to be addressed in order to improve education in this field
Fuzzy Control Strategy for an Anaerobic Wastewater Treatment Process
In this paper, a fuzzy control strategy (FCS) for an anaerobic wastewater treatment process is proposed in order to reject large disturbances on input substrate allowing a high methane production. This strategy is composed of: i) a state observer, which is based on a principal components analysis (PCA) and Takagi-Sugeno (TS) algorithm; it is designed to estimate variables hard to measure: biomass and substrate, ii) proportional-integral (PI) controllers based on a combination of the L/A(logarithm/antilogarithm) and fuzzy approaches; these controllers have variable gains and are designed to regulate bicarbonate in the reactor by two control actions: a base supplying (binc) and dilution rate (D) changes, iii) a TS supervisor which detects the process state, selects and applies the most adequate control action, allowing a smooth switching between open
loop and closed loop. Applicability of the proposed structure in a completely stirred tank reactor (CSTR) is illustrated via simulations. The obtained results show that the process works in open loop in presence of small disturbances. For large disturbances, the supervisor allows the control actions to be applied avoiding washout; after that, the process returns to open loop operation. In general, the FCS improves the performances of the anaerobic process and is feasible for application in real processes, since the control scheme
shows a good compromise between efficiency and complexity
Current profiles and AC losses of a superconducting strip with elliptic cross-section in perpendicular magnetic field
The case of a hard type II superconductor in the form of strip with elliptic
cross-section when placed in transverse magnetic field is studied. We approach
the problem in two steps, both based on the critical-state model. First we
calculate numerically the penetrated current profiles that ensure complete
shielding in the interior, without assuming an a priori form for the profiles.
In the second step we introduce an analytical approximation that asumes that
the current profiles are ellipses. Expressions linking the sample magnetization
to the applied field are derived covering the whole range of applied fields.
The theoretical predictions are tested by the comparison with experimental data
for the imaginary part of AC susceptibility.Comment: 12 pages; 3 figure
Quantum corrections to the inflaton potential and the power spectra from superhorizon modes and trace anomalies
We obtain the effective inflaton potential during slow roll inflation by
including the one loop quantum corrections to the energy momentum tensor from
scalar curvature and tensor perturbations as well as quantum fluctuations from
light scalars and light Dirac fermions generically coupled to the inflaton.
During slow roll inflation there is a clean and unambiguous separation between
superhorizon and subhorizon contributions to the energy momentum tensor. The
superhorizon part is determined by the curvature perturbations and scalar field
fluctuations: both feature infrared enhancements as the inverse of a
combination of slow roll parameters which measure the departure from scale
invariance in each case.Fermions and gravitons do not exhibit infrared
divergences. The subhorizon part is completely specified by the trace anomaly
of the fields with different spins and is solely determined by the space-time
geometry. The one-loop quantum corrections to the amplitude of curvature and
tensor perturbations are obtained to leading order in slow-roll and in the
(H/M_PL)^2 expansion. This study provides a complete assessment of the
backreaction problem up to one loop including bosonic and fermionic degrees of
freedom. The result validates the effective field theory description of
inflation and confirms the robustness of the inflationary paradigm to quantum
fluctuations. Quantum corrections to the power spectra are expressed in terms
of the CMB observables:n_s, r and dn_s/dln k. Trace anomalies (especially the
graviton part) dominate these quantum corrections in a definite direction: they
enhance the scalar curvature fluctuations and reduce the tensor fluctuations.Comment: 18 pages, no figure
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