680 research outputs found
A Coupled Quantum Otto Cycle
We study the 1-d isotropic Heisenberg model of two spin-1/2 systems as a
quantum heat engine. The engine undergoes a four-step Otto cycle where the two
adiabatic branches involve changing the external magnetic field at a fixed
value of the coupling constant. We find conditions for the engine efficiency to
be higher than the uncoupled model; in particular, we find an upper bound which
is tighter than the Carnot bound. A new domain of parameter values is pointed
out which was not feasible in the interaction-free model. Locally, each spin
seems to effect the flow of heat in a direction opposite to the global
temperature gradient. This seeming contradiction to the second law can be
resolved in terms of local effective temperature of the spins
Neither Fear Nor Favour, Affection Or Ill Will: Modernisation of care proceedings and the use and value of independent social work expertise to senior judges
This is part two of an evaluation of the work of independent social work experts (ISWs) in care proceedings (stage I was published in April 2012). It takes forward findings from stage I exploring further the evidential base for views put to the Family Justice Review about the practice of courts. It examines the views, experiences and practices of a sample of senior judges in commissioning ISW assessments, placing these in the context of the timing, format and value of local authority assessments. Finally, judges? views about the implications of the modernisation programme for use of ISWs are explored - in the light of a need for earlier completion of cases, without loss of quality in assessments, and with regard to issues of fairness, justice and transparency in judicial decision making. In the report each section is followed by a summary of findings reflecting the key issue for policy and practice. The study is based on interviews with 23 senior judges (20 DFJs, 3 Circuit Judges) in 20/43 county courts in England and Wales. Interviews were held between February and April 2013. They include representation from all circuits, and courts with small and high volume case loads (less than 115, 251 - 900 applications in 12 months). They hear applications from just over half of authorities in England (59%) and just over one third (36%) in Wales
Universal efficiency at optimal work with Bayesian statistics
If the work per cycle of a quantum heat engine is averaged over an
appropriate prior distribution for an external parameter , the work becomes
optimal at Curzon-Ahlborn efficiency. More general priors of the form yield optimal work at an efficiency which stays close to
CA value, in particular near equilibrium the efficiency scales as one-half of
the Carnot value. This feature is analogous to the one recently observed in
literature for certain models of finite-time thermodynamics. Further, the use
of Bayes' theorem implies that the work estimated with posterior probabilities
also bears close analogy with the classical formula. These findings suggest
that the notion of prior information can be used to reveal thermodynamic
features in quantum systems, thus pointing to a new connection between
thermodynamic behavior and the concept of information.Comment: revtex4, 5 pages, abstract changed and presentation improved; results
unchanged. New result with Bayes Theorem adde
The contribution of experts in care proceedings : evaluation of independent social work reports on care proceedings
Several concerns surround the use of independent social work (ISW) assessments in care proceedings. Some result from the exclusion of this work from a review of legal aid for expert assessments in this field, a cap on ISW fees, and fears about a resulting reduction in the availability of ISWs. At the same time, submissions to the Family Justice Review (FJR) claimed that ISWs cause delay, simply duplicate existing local authority assessments, add nothing new and undermine confidence in social work assessments. It was also said that ISW reports result from parents utilising human rights claims to gain a second opinion of a local authority assessment ? and to which courts too readily accede. ... But while strong views have been expressed about the use of independent social work assessments, there is little hard evidence. This evaluation, commissioned following submissions to the FJR, begins to address that lack. It is based on 65 cases concerning 121 children and 82 reports for courts in England and Wales. The sample was drawn from the records of three independent agencies providing ISWs
Ignorance based inference of optimality in thermodynamic processes
We derive ignorance based prior distribution to quantify incomplete
information and show its use to estimate the optimal work characteristics of a
heat engine.Comment: Latex, 10 pages, 3 figure
(How) does productivity matter in the foundational economy?
Academics and policy makers have increasingly recognised the importance of mundane economic activities – variously termed foundational or everyday – by academics and policy makers. The foundational or everyday economy is now featuring in local industrial strategy and economic action plans, because the desirable high-tech sectors on the ‘frontier’ cannot diffuse prosperity within and between regions. This paper aims to distinguish between several different approaches to the foundational or everyday economy and argues that a constructive approach needs to break with the preoccupation about improving productivity. This argument is developed in three stages. First, we distinguish between a social approach and a more technical economic approach to delimiting this other mundane economy; the defining feature of the foundational in the social approach is contribution to wellbeing and in the technical economic approach it is low productivity. The second section presents and explores productivity evidence on output per worker hour across a range of foundational activities and by region. Drawing out the implications of observed diversity and heterogeneity, the third section develops an argument about how productivity has limited relevance as measure and target in foundational activitie
A closed loop audit: implementing a protocol for venous thromboembolism prophylaxis in patients discharged non-weight bearing and in below knee cast after lower limb fracture in a london district general hospital
Ruthenium volatilisation from reprocessed spent nuclear fuel - Studying the baseline thermodynamics of Ru(III)
Ruthenium is a fission product possessed of two relatively long lived isotopes, Ru and Ru, both of which form part of the Highly Active (HA) waste raffinate during spent nuclear fuel reprocessing. During reprocessing ruthenium, which may be in the form of the RuNO+ complex, encounters temperatures conducive to volatilization. Due rutheium's high specific radioactivity it is important to understand the mechanism by which volatilisation occurs. Here we use combined CV, RDE and electrochemical microgravimetry experiments in a study of the the RuCl3 system for the first time. We do this in the interest of establishing NO-free Ru(III) baseline behaviour so as to support future studies on NO complexed ruthenium. Using wide aqueous solvent window carbon electrodes we have observed discrete oxidations to a solution phase Ru(III)-Ru(IV)-Ru(III) trimer, to solid RuO2 and volatile RuO4. We have also observed and assigned discrete reductions of solid RuO2 back to Ru(III) and Ru(III) reduction to ruthenium metal
Coupling theory for counterion distributions based in Tsallis statistics
It is well known that the Poisson-Boltzmann (PB) equation yields the exact
counterion density around charged objects in the weak coupling limit. In this
paper we generalize the PB approach to account for coupling of arbitrary
strength by making use of Tsallis q-exponential distributions. Both the weak
coupling and the strong coupling limits are reproduced. For arbitrary coupling
we also provide simple analytical expressions which are compared to recent
Monte Carlo simulations by A. G. Moreira and R. R. Netz [Europhys. Lett. 52
(2000) 705]. Excellent agreement with these is obtained.Comment: 17 pages, 2 figures, 1 table. Final version, accepted for publication
in Physica
Barnett-Pegg formalism of angle operators, revivals, and flux lines
We use the Barnett-Pegg formalism of angle operators to study a rotating
particle with and without a flux line. Requiring a finite dimensional version
of the Wigner function to be well defined we find a natural time quantization
that leads to classical maps from which the arithmetical basis of quantum
revivals is seen. The flux line, that fundamentally alters the quantum
statistics, forces this time quantum to be increased by a factor of a winding
number and determines the homotopy class of the path. The value of the flux is
restricted to the rational numbers, a feature that persists in the infinite
dimensional limit.Comment: 5 pages, 0 figures, Revte
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