2,827 research outputs found
Dichotomous Hamiltonians with Unbounded Entries and Solutions of Riccati Equations
An operator Riccati equation from systems theory is considered in the case
that all entries of the associated Hamiltonian are unbounded. Using a certain
dichotomy property of the Hamiltonian and its symmetry with respect to two
different indefinite inner products, we prove the existence of nonnegative and
nonpositive solutions of the Riccati equation. Moreover, conditions for the
boundedness and uniqueness of these solutions are established.Comment: 31 pages, 3 figures; proof of uniqueness of solutions added; to
appear in Journal of Evolution Equation
Calculation of the spectrum of 12Li by using the multistep shell model method in the complex energy plane
The unbound nucleus Li is evaluated by using the multistep shell model
in the complex energy plane assuming that the spectrum is determined by the
motion of three neutrons outside the Li core. It is found that the ground
state of this system consists of an antibound state and that only this
and a and a excited states are physically meaningful
resonances.Comment: 9 pages, 5 tables, 7 figures, printer-friendly versio
The good character at work: an initial study on the contribution of character strengths in identifying healthy and unhealthy work-related behavior and experience patterns
Purpose: Positive psychological functioning has been related to various positive work-related outcome variables, such as job satisfaction or work engagement. The aim of the present study was to examine the relations between morally positively valued traits (i.e., strengths of character) and work-related behaviors. Method: A sample of 887 adult women completed the Values in Action Inventory of Strengths (VIA-IS) and the Work-related Behavior and Experience Patterns Questionnaire (AVEM) in an online survey. Results: Those assigned to healthy work-related behavior and experience patterns differed in their strengths profiles from those that demonstrated unhealthy patterns (i.e., burnout type) in a predictable way. Especially the strengths of zest, persistence, hope, and curiosity seemed to play a key role in healthy and ambitious work behavior. Conclusions: The study underlines the relevance of character strengths in work settings and suggests that interventions based on character strengths could substantiate interventions already existing at the workplace in order to enhance positive work outcomes further (e.g., work satisfaction, engagement
Pairing in Nuclei
Simple generic aspects of nuclear pairing in homogeneous medium as well as in
finite nuclei are discussed. It is argued that low-energy nuclear structure is
not sensitive enough to resolve fine details of nuclear nucleon-nucleon (NN)
interaction in general and pairing NN interaction in particular what allows for
regularization of the ultraviolet (high-momentum) divergences and a consistent
formulation of effective superfluid local theory. Some aspects of
(dis)entanglement of pairing with various other effects as well as forefront
ideas concerning isoscalar pairing are also briefly discussed.Comment: Invited talk presented at the International Conference on Finite
Fermionic Systems, Nilsson Model 50 Years,Lund, Sweden, June 14-18, 2005, 7
LaTeX pages, 4 encapsulated postscript figure
Can Action Research Strengthen District Health Management and Improve Health Workforce Performance? A Research Protocol.
The single biggest barrier for countries in sub-Saharan Africa (SSA) to scale up the necessary health services for addressing the three health-related Millennium Development Goals and achieving Universal Health Coverage is the lack of an adequate and well-performing health workforce. This deficit needs to be addressed both by training more new health personnel and by improving the performance of the existing and future health workforce. However, efforts have mostly been focused on training new staff and less on improving the performance of the existing health workforce. The purpose of this paper is to disseminate the protocol for the PERFORM project and reflect on the key challenges encountered during the development of this methodology and how they are being overcome. The overall aim of the PERFORM project is to identify ways of strengthening district management in order to address health workforce inadequacies by improving health workforce performance in SSA. The study will take place in three districts each in Ghana, Tanzania and Uganda using an action research approach. With the support of the country research teams, the district health management teams (DHMTs) will lead on planning, implementation, observation, reflection and redefinition of the activities in the study. Taking into account the national and local human resource (HR) and health systems (HS) policies and practices already in place, 'bundles' of HR/HS strategies that are feasible within the context and affordable within the districts' budget will be developed by the DHMTs to strengthen priority areas of health workforce performance. A comparative analysis of the findings from the three districts in each country will add new knowledge on the effects of these HR/HS bundles on DHMT management and workforce performance and the impact of an action research approach on improving the effectiveness of the DHMTs in implementing these interventions. Different challenges were faced during the development of the methodology. These include the changing context in the study districts, competing with other projects and duties for the time of district managers, complexity of the study design, maintaining the anonymity and confidentiality of study participants as well as how to record the processes during the study. We also discuss how these challenges are being addressed. The dissemination of this research protocol is intended to generate interest in the PERFORM project and also stimulate discussion on the use of action research in complex studies such as this on strengthening district health management to improve health workforce performance
Far-infrared induced current in a ballistic channel -- potential barrier structure
We consider electron transport in a ballistic multi-mode channel structure in
the presence of a transversely polarized far-infrared (FIR) field. The channel
structure consists of a long resonance region connected to an adiabatic
widening with a potential barrier at the end. At frequencies that match the
mode energy separation in the resonance region we find distinct peaks in the
photocurrent, caused by Rabi oscillations in the mode population. For an
experimental situation in which the width of the channel is tunable via gates,
we propose a method for reconstructing the spectrum of propagating modes,
without having to use a tunable FIR source. With this method the change in the
spectrum as the gate voltage is varied can be monitored.Comment: Submitted to Phys. Rev.
Global nuclear structure effects of tensor interaction
A direct fit of the isoscalar spin-orbit (SO) and both isoscalar and
isovector tensor coupling constants to the f5/2-f7/2 SO splittings in 40Ca,
56Ni, and 48Ca nuclei requires a drastic reduction of the isoscalar SO strength
and strong attractive tensor coupling constants. The aim of this work is to
address further consequences of these strong attractive tensor and weak SO
fields on binding energies, nuclear deformability, and high-spin states. In
particular, we show that contribution to the nuclear binding energy due to the
tensor field shows generic magic structure with tensorial magic numbers at
N(Z)=14, 32, 56, or 90 corresponding to the maximum spin-asymmetries in 1d5/2,
1f7/2-2p3/2, 1g9/2-2d5/2 and 1h11/2-2f7/2 single-particle configurations and
that these numbers are smeared out by pairing correlations and deformation
effects. We also examine the consequences of strong attractive tensor fields
and weak SO interaction on nuclear stability at the drip lines, in particular
close to the tensorial doubly magic nuclei and discuss the possibility of an
entirely new tensor-force driven deformation effect.Comment: replaced with published versio
Shape and blocking effects on odd-even mass differences and rotational motion of nuclei
Nuclear shapes and odd-nucleon blockings strongly influence the odd-even
differences of nuclear masses. When such effects are taken into account, the
determination of the pairing strength is modified resulting in larger pair
gaps. The modified pairing strength leads to an improved self-consistent
description of moments of inertia and backbending frequencies, with no
additional parameters.Comment: 7 pages, 3 figures, subm to PR
Coherence features of the spin-aligned neutron-proton pair coupling scheme
The seniority scheme has been shown to be extremely useful for the
classification of nuclear states in semi-magic nuclei. The neutron-proton
() correlation breaks the seniority symmetry in a major way. As a result,
the corresponding wave function is a mixture of many components with different
seniority quantum numbers. In this contribution we show that the
interaction may favor a new kind of coupling in nuclei, i.e., the
so-called isoscalar spin-aligned pair mode. Shell model calculations
reveal that the ground and low-lying yrast states of the nuclei
Pd and Cd may mainly be built upon such spin-aligned pairs
each carrying the maximum angular momentum allowed by the shell
which is dominant in this nuclear region.Comment: 5 pages, 4 figues, Proceedings of the Nordic Conference on Nuclear
Physics 2011. To appear in Physica Scripta
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