94,269 research outputs found
Thermodynamics of baryonic matter with strangeness within non-relativistic energy density functional model
We study the thermodynamical properties of compressed baryonic matter with
strangeness within non-relativistic energy density functional models with a
particular emphasis on possible phase transitions found earlier for a simple
-mixture. The aim of the paper is twofold: I) examining the
phase structure of the complete system, including the full baryonic octet and
II) testing the sensitivity of the results to the model parameters. We find
that, associated to the onset of the different hyperonic families, up to three
separate strangeness-driven phase transitions may occur. Consequently, a large
fraction of the baryonic density domain is covered by phase coexistence with
potential relevance for (proto)-neutron star evolution. It is shown that the
presence of a phase transition is compatible both with the observational
constraint on the maximal neutron star mass, and with the present experimental
information on hypernuclei. In particular we show that two solar mass neutron
stars are compatible with important hyperon content. Still, the parameter space
is too large to give a definitive conclusion of the possible occurrence of a
strangeness driven phase transition, and further constraints from
multiple-hyperon nuclei and/or hyperon diffusion data are needed.Comment: 11 pages, 7 figure
Modification of magicity towards the dripline and its impact on electron-capture rates for stellar core-collapse
The importance of microphysical inputs from laboratory nuclear experiments
and theoretical nuclear structure calculations in the understanding of the core
collapse dynamics, and the subsequent supernova explosion, is largely
recognized in the recent literature. In this work, we analyze the impact of the
masses of very neutron rich nuclei on the matter composition during collapse,
and the corresponding electron capture rate. To this aim, we introduce an
empirical modification of the popular Duflo-Zuker mass model to account for
possible shell quenching far from stability, and study the effect of the
quenching on the average electron capture rate. We show that the preeminence of
the and closed shells in the collapse dynamics is considerably
decreased if the shell gaps are reduced in the region of Ni and beyond.
As a consequence, local modifications of the overall electron capture rate up
to 30\% can be expected, with integrated values strongly dependent on the
stiffness of magicity quenching and progenitor mass and potential important
consequences on the entropy generation, the neutrino emissivity, and the mass
of the core at bounce. Our work underlines the importance of new experimental
measurements in this region of the nuclear chart, the most crucial information
being the nuclear mass and the Gamow-Teller strength. Reliable microscopic
calculations of the associated elementary rate, in a wide range of temperatures
and electron densities, optimized on these new empirical information, will be
additionally needed to get quantitative predictions of the collapse dynamics.Comment: 12 pages, 10 figure
Quantum thermodynamics at critical points during melting and solidification processes
We systematically explore and show the existence of finite-temperature
continuous quantum phase transition (CTQPT) at a critical point, namely, during
solidification or melting such that the first-order thermal phase transition is
a special case within CTQPT. Infact, CTQPT is related to chemical reaction
where quantum fluctuation (due to wavefunction transformation) is caused by
thermal energy and it can occur maximally for temperatures much higher than
zero Kelvin. To extract the quantity related to CTQPT, we use the ionization
energy theory and the energy-level spacing renormalization group method to
derive the energy-level spacing entropy, renormalized Bose-Einstein
distribution and the time-dependent specific heat capacity. This work
unambiguously shows that the quantum phase transition applies for any finite
temperatures.Comment: To be published in Indian Journal of Physics (Kolkata
Levels of abstraction in human supervisory control teams
This paper aims to report a study into the levels of abstraction hierarchy (LOAH) in two energy distribution teams. The original proposition for the LOAH was that it depicted five levels of system representation, working from functional purpose through to physical form to determine causes of a malfunction, or from physical form to functional purpose to determine the purpose of system function. The LOAH has been widely used throughout human supervisory control research to explain individual behaviour. The research seeks to focus on the application the LOAH to human supervisory control teams in semi-automated âintelligentâ systems
Solving QCD evolution equations in rapidity space with Markovian Monte Carlo
This work covers methodology of solving QCD evolution equation of the parton
distribution using Markovian Monte Carlo (MMC) algorithms in a class of models
ranging from DGLAP to CCFM. One of the purposes of the above MMCs is to test
the other more sophisticated Monte Carlo programs, the so-called Constrained
Monte Carlo (CMC) programs, which will be used as a building block in the
parton shower MC. This is why the mapping of the evolution variables (eikonal
variable and evolution time) into four-momenta is also defined and tested. The
evolution time is identified with the rapidity variable of the emitted parton.
The presented MMCs are tested independently, with ~0.1% precision, against the
non-MC program APCheb especially devised for this purpose.Comment: version compatible with with the erratum in Acta Physica Polonic
Collaborative working in highways major maintenance projects
Over the last decade, there has been a growing emphasis on collaborations and partnering in the construction industry. This has been embraced in the UK highways maintenance sector, with partnering promoted by the client, leading to the formation of alliances and partnering frameworks. One of these is the construction management framework (CMF), the preferred method of procurement for major maintenance projects in the Highways Agencyâs areas 9 and 10. This paper compares two road and structure renewals schemes carried out using the CMF. The first scheme was carried out in 2004 as one of the first of its type to be undertaken by the CMF; the second was a similar project carried out in 2006. Documentation of the two projects was reviewed to identify the benefits that were gained through working in collaboration, and if there was an improvement in performance as the framework became more established. The research considered key performance indicators, including cost and time predictability measures, respect for people surveys, innovations and lessons learned discussed at the time of the projects, and instructions for changes to works information. Data collected from both schemes show improvements in measurement and culture fostered by the CMF, and the advantages of the processes used are illustrated
Road user charging and implications for transport policy: Findings from the CURACAO project
This paper reports on the outcomes of a European project, CURACAO, designed to support the implementation of urban road user charging (URUC) as a demand management tool in urban areas. The project did this through engagement with a User Group of cities interested in pursuing URUC to identify the barriers preventing them from doing so.
The project reviewed the complete process of setting up a URUC scheme from the setting of objectives, through to scheme design, predicting impacts, achieving acceptability and the implementation process and presented its findings in a State of the Art Report and a Case Studies Report. The State of the Art Report provides evidence collated from research and practice to address a series of 14 themes identified by the User Group, including objectives; scheme design; technology; business systems; prediction; traffic, environmental, economic and equity impacts; appraisal; acceptability; transferability; implementation; and evaluation. The Case Study Report reviewed 16 proposed or implemented schemes in Europe, focusing on pricing objectives, scheme design, the implementation process and scheme results. On this basis, the CURACAO Consortium developed a list of policy recommendations aimed at cities and regional authorities, national governments, and the European Commission.
The paper summarises the main findings of the State of the Art Report and the case studies. On this basis, it outlines the policy recommendations which were drawn, and identifies future research needs
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