91 research outputs found
Nonergodic behavior of the clean Bose-Hubbard chain
We study ergodicity breaking in the clean Bose-Hubbard chain for small
hopping strength. We see the existence of a non-ergodic regime by means of
indicators as the half-chain entanglement entropy of the eigenstates, the
average level spacing ratio, {the properties of the eigenstate-expectation
distribution of the correlation and the scaling of the Inverse Participation
Ratio averages.} We find that this ergodicity breaking {is different from
many-body localization} because the average half-chain entanglement entropy of
the eigenstates obeys volume law. This ergodicity breaking appears unrelated to
the spectrum being organized in quasidegenerate multiplets at small hopping and
finite system sizes, so in principle it can survive also for larger system
sizes. We find that some imbalance oscillations in time which could mark the
existence of a glassy behaviour in space are well described by the dynamics of
a single symmetry-breaking doublet and {quantitatively} captured by a
perturbative effective XXZ model. We show that the amplitude of these
oscillations vanishes in the large-size limit. {Our findings are numerically
obtained for systems with . Extrapolations of our scalings to larger
system sizes should be taken with care, as discussed in the paper.Comment: 18 pages, 13 figures, extensively revised version published in
Physical Review B, Eq. (21) in the correct for
3D KINEMATICAL ANALYSIS OF BRAZILIAN FEMALE POLE VAULTERS
Pole Vault is one of the most technical events in track and field. Schade et al. (2005) evaluated kinematical and dynamic variables during the 2005 World Championship in Helsinki providing data of world class vaulters for comparison. Recently, Brazilian pole vaulters have obtained world class results but, despite this, no biomechanical analysis has been conducted with such athletes. Therefore, the aim of this work is the 3D kinematical analysis of the best female athletes during the “XXVII Brazilian Trophy” in 2008
Entanglement entropy in a periodically driven Ising chain
In this work we study the entanglement entropy of a uniform quantum Ising chain in transverse field undergoing a periodic driving of period \u3c4. By means of Floquet theory we show that, for any subchain, the entanglement entropy tends asymptotically to a value \u3c4-periodic in time. We provide a semi-analytical formula for the leading term of this asymptotic regime: It is constant in time and obeys a volume law. The entropy in the asymptotic regime is always smaller than the thermal one: because of integrability the system locally relaxes to a generalized Gibbs ensemble (GGE) density matrix. The leading term of the asymptotic entanglement entropy is completely determined by this GGE density matrix. Remarkably, the asymptotic entropy shows marked features in correspondence to some non-equilibrium quantum phase transitions undergone by a Floquet state analog of the ground state
Boundary time crystals
This work was supported in part by \Progetti Interni - Scuola Normale Superiore" (A.R.), EU- 691 QUIC (R.F. and A.R.), CRF Singapore Ministry of Education (CPR-QSYNC 692) (R.F.), EPSRC program TOPNES (EP/I031014/1) (J.K.).In this work we introduce boundary time crystals. Here continuous time-translation symmetry breaking occurs only in a macroscopic fraction of a many-body quantum system. After introducing their definition and properties, we analyze in detail a solvable model where an accurate scaling analysis can be performed. The existence of the boundary time crystals is intimately connected to the emergence of a time-periodic steady state in the thermodynamic limit of a many-body open quantum system. We also discuss connections to quantum synchronization.PostprintPeer reviewe
The anti-ageing molecule sirt1 mediates beneficial effects of cardiac rehabilitation
Background An exercise-based Cardiac Rehabilitation Programme (CRP) is established as adjuvant therapy in heart failure (HF), nevertheless it is underutilized, especially in the elderly. While the functional and hemodynamic effects of CRP are well known, its underlying molecular mechanisms have not been fully clarified. The present study aims to evaluate the effects of a well-structured 4-week CRP in patients with stable HF from a molecular point of view. Results A prospective longitudinal observational study was conducted on patients consecutively admitted to cardiac rehabilitation. In fifty elderly HF patients with preserved ejection fraction (HFpEF), levels of sirtuin 1 (Sirt1) in peripheral blood mononuclear cells (PBMCs) and of its targets, the antioxidants catalase (Cat) and superoxide dismutase (SOD) in serum were measured before (Patients, P) and at the end of the CRP (Rehabilitated Patients, RP), showing a rise of their activities after rehabilitation. Endothelial cells (ECs) were conditioned with serum from P and RP, and oxidative stress was induced using hydrogen peroxide. An increase of Sirt1 and Cat activity was detected in RP-conditioned ECs in both the absence and presence of oxidative stress, together with a decrease of senescence, an effect not observed during Sirt1 and Cat inhibition. Conclusions In addition to the improvement in functional and hemodynamic parameters, a supervised exercise-based CRP increases Sirt1 activity and stimulates a systemic antioxidant defence in elderly HFpEF patients. Moreover, CRP produces antioxidant and anti-senescent effects in human endothelial cells mediated, at least in part, by Sirt1 and its target Cat
Knowledge and health care resource allocation: CME/CPD course guidelines-based efficacy.
BACKGROUND: Most health care systems consider continuing medical education a potential tool to improve quality of care and reduce disease management costs. Its efficacy in general practitioners needs to be further explored.
OBJECTIVE: This study assesses the effectiveness of a one-year continuing medical education/continuing professional development course for general practitioners, regarding the improvement in knowledge of ARIA and GINA guidelines and compliance with them in asthma management.
METHODS: Sixty general practitioners, covering 68,146 inhabitants, were randomly allocated to continuing medical education/continuing professional development (five residential events +four short distance-learning refresher courses over one year) or no training. Participants completed a questionnaire after each continuing medical education event; key questions were repeated at least twice. The Local Health Unit prescription database was used to verify prescription habits (diagnostic investigations and pharmacological therapy) and hospitalizations over one year before and after training.
RESULTS: Fourteen general practitioners (46.7%) reached the cut-off of 50% attendance of the training courses. Knowledge improved significantly after training (p < 0.001, correct answers to key questions +13%). Training resulted in pharmaceutical cost containment (trained general practitioners +0.5% vs. controls +18.8%) and greater attention to diagnosis and monitoring (increase in spirometry +63.4%, p < 0.01).
CONCLUSION: This study revealed an encouraging impact of educational events on improvement in general practitioner knowledge of guidelines and daily practice behavioral changes. Long-term studies of large populations are required to assess the effectiveness of education on the behavior of physicians in asthma management, and to establish the best format for educational events
Estudo das condições sanitárias das águas de piscinas públicas e particulares, na cidade de Araraquara, SP, Brasil
Crescimento e produção de capĂtulos florais de calĂŞndula em resposta Ă inoculação micorrĂzica e fĂłsforo
FUNGOS MICORRIZICOS ARBUSCULARES NO DESENVOLVIMENTO DE MUDAS DE OLIVEIRA (OLEA EUROPAEA L.) CULTIVADAS NO SUL DE MINAS GERAIS
Fungos conidiais em Euterpe oleracea Mart. (açaizeiro) na Ilha do Combu, Pará-Brasil
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