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Bastarrachea-Magnani MA, Villaseñor D, Chávez-Carlos J, Lerma-Hernández S, Santos LF, Hirsch JG. Quantum multifractality as a probe of phase space in the Dicke model. Phys Rev E 2024; 109:034202. [PMID: 38632765 DOI: 10.1103/physreve.109.034202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 01/31/2024] [Indexed: 04/19/2024]
Abstract
We study the multifractal behavior of coherent states projected in the energy eigenbasis of the spin-boson Dicke Hamiltonian, a paradigmatic model describing the collective interaction between a single bosonic mode and a set of two-level systems. By examining the linear approximation and parabolic correction to the mass exponents, we find ergodic and multifractal coherent states and show that they reflect details of the structure of the classical phase space, including chaos, regularity, and features of localization. The analysis of multifractality stands as a sensitive tool to detect changes and structures in phase space, complementary to classical tools to investigate it. We also address the difficulties involved in the multifractal analyses of systems with unbounded Hilbert spaces.
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Affiliation(s)
- M A Bastarrachea-Magnani
- Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, Av. Ferrocarril San Rafael Atlixco 186, C.P. 09310 Mexico City, Mexico
| | - D Villaseñor
- Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas, Universidad Nacional Autónoma de México, C.P. 04510, Mexico City, Mexico
| | - J Chávez-Carlos
- Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA
| | - S Lerma-Hernández
- Facultad de Física, Universidad Veracruzana, Campus Arco Sur, Paseo 112, C.P. 91097 Xalapa, Mexico
| | - L F Santos
- Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA
| | - J G Hirsch
- Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apdo. Postal 70-543, C.P. 04510 Mexico City, Mexico
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Costa NS, Oliveira LMA, Rio-Tinto A, Pinto IBF, Oliveira AEAS, Santana JDD, Santos LF, Costa RSN, Marinho PS, Fracalanzza SEL, Teixeira LM, Pinto TCA. Anovaginal Colonization by Group B Streptococcus and Streptococcus anginosus among Pregnant Women in Brazil and Its Association with Clinical Features. Antibiotics (Basel) 2024; 13:85. [PMID: 38247643 PMCID: PMC10812730 DOI: 10.3390/antibiotics13010085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 01/08/2024] [Accepted: 01/11/2024] [Indexed: 01/23/2024] Open
Abstract
Streptococcus agalactiae (Group B Streptococcus; GBS) is a leading cause of neonatal invasive disease worldwide. GBS can colonize the human gastrointestinal and genitourinary tracts, and the anovaginal colonization of pregnant women is the main source for neonatal infection. Streptococcus anginosus, in turn, can colonize the human upper respiratory, gastrointestinal, and genitourinary tracts but has rarely been observed causing disease. However, in the last years, S. anginosus has been increasingly associated with human infections, mainly in the bloodstream and gastrointestinal and genitourinary tracts. Although anovaginal screening for GBS is common during pregnancy, data regarding the anovaginal colonization of pregnant women by S. anginosus are still scarce. Here, we show that during the assessment of anovaginal GBS colonization rates among pregnant women living in Rio de Janeiro, Brazil, S. anginosus was also commonly detected, and S. anginosus isolates presented a similar colony morphology and color pattern to GBS in chromogenic media. GBS was detected in 48 (12%) while S. anginosus was detected in 17 (4.3%) of the 399 anovaginal samples analyzed. The use of antibiotics during pregnancy and history of urinary tract infections and sexually transmitted infections were associated with the presence of S. anginosus. In turn, previous preterm birth was associated with the presence of GBS (p < 0.05). The correlation of GBS and S. anginosus with relevant clinical features of pregnant women in Rio de Janeiro, Brazil, highlights the need for the further investigation of these important bacteria in relation to this special population.
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Affiliation(s)
- Natalia Silva Costa
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (N.S.C.); (L.M.A.O.); (A.R.-T.); (I.B.F.P.); (A.E.A.S.O.); (J.d.D.S.); (L.F.S.); (R.S.N.C.); (S.E.L.F.); (L.M.T.)
| | - Laura Maria Andrade Oliveira
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (N.S.C.); (L.M.A.O.); (A.R.-T.); (I.B.F.P.); (A.E.A.S.O.); (J.d.D.S.); (L.F.S.); (R.S.N.C.); (S.E.L.F.); (L.M.T.)
| | - Andre Rio-Tinto
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (N.S.C.); (L.M.A.O.); (A.R.-T.); (I.B.F.P.); (A.E.A.S.O.); (J.d.D.S.); (L.F.S.); (R.S.N.C.); (S.E.L.F.); (L.M.T.)
| | - Isabella Bittencourt Ferreira Pinto
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (N.S.C.); (L.M.A.O.); (A.R.-T.); (I.B.F.P.); (A.E.A.S.O.); (J.d.D.S.); (L.F.S.); (R.S.N.C.); (S.E.L.F.); (L.M.T.)
| | - Ana Elisa Almeida Santos Oliveira
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (N.S.C.); (L.M.A.O.); (A.R.-T.); (I.B.F.P.); (A.E.A.S.O.); (J.d.D.S.); (L.F.S.); (R.S.N.C.); (S.E.L.F.); (L.M.T.)
| | - Julia de Deus Santana
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (N.S.C.); (L.M.A.O.); (A.R.-T.); (I.B.F.P.); (A.E.A.S.O.); (J.d.D.S.); (L.F.S.); (R.S.N.C.); (S.E.L.F.); (L.M.T.)
| | - Laiane Ferreira Santos
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (N.S.C.); (L.M.A.O.); (A.R.-T.); (I.B.F.P.); (A.E.A.S.O.); (J.d.D.S.); (L.F.S.); (R.S.N.C.); (S.E.L.F.); (L.M.T.)
| | - Rayssa Santos Nogueira Costa
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (N.S.C.); (L.M.A.O.); (A.R.-T.); (I.B.F.P.); (A.E.A.S.O.); (J.d.D.S.); (L.F.S.); (R.S.N.C.); (S.E.L.F.); (L.M.T.)
| | - Penelope Saldanha Marinho
- Faculdade de Medicina, Maternidade Escola, Universidade Federal do Rio de Janeiro, Rio de Janeiro 22240-000, Brazil;
| | - Sergio Eduardo Longo Fracalanzza
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (N.S.C.); (L.M.A.O.); (A.R.-T.); (I.B.F.P.); (A.E.A.S.O.); (J.d.D.S.); (L.F.S.); (R.S.N.C.); (S.E.L.F.); (L.M.T.)
| | - Lucia Martins Teixeira
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (N.S.C.); (L.M.A.O.); (A.R.-T.); (I.B.F.P.); (A.E.A.S.O.); (J.d.D.S.); (L.F.S.); (R.S.N.C.); (S.E.L.F.); (L.M.T.)
| | - Tatiana Castro Abreu Pinto
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (N.S.C.); (L.M.A.O.); (A.R.-T.); (I.B.F.P.); (A.E.A.S.O.); (J.d.D.S.); (L.F.S.); (R.S.N.C.); (S.E.L.F.); (L.M.T.)
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Lerma-Hernández S, Villaseñor D, Bastarrachea-Magnani MA, Torres-Herrera EJ, Santos LF, Hirsch JG. Dynamical signatures of quantum chaos and relaxation time scales in a spin-boson system. Phys Rev E 2019; 100:012218. [PMID: 31499773 DOI: 10.1103/physreve.100.012218] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Indexed: 06/10/2023]
Abstract
Quantum systems whose classical counterparts are chaotic typically have highly correlated eigenvalues and level statistics that coincide with those from ensembles of full random matrices. A dynamical manifestation of these correlations comes in the form of the so-called correlation hole, which is a dip below the saturation point of the survival probability's time evolution. In this work, we study the correlation hole in the spin-boson (Dicke) model, which presents a chaotic regime and can be realized in experiments with ultracold atoms and ion traps. We derive an analytical expression that describes the entire evolution of the survival probability and allows us to determine the time scales of its relaxation to equilibrium. This expression shows remarkable agreement with our numerical results. While the initial decay and the time to reach the minimum of the correlation hole depend on the initial state, the dynamics beyond the hole up to equilibration is universal. We find that the relaxation time of the survival probability for the Dicke model increases linearly with system size.
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Affiliation(s)
- S Lerma-Hernández
- Facultad de Física, Universidad Veracruzana, Circuito Aguirre Beltrán s/n, Xalapa, Veracruz 91000, Mexico
| | - D Villaseñor
- Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apdo. Postal 70-543, C.P. 04510 Cd. Mx., Mexico
| | | | - E J Torres-Herrera
- Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apdo. Postal J-48, Puebla, Puebla 72570, Mexico
| | - L F Santos
- Department of Physics, Yeshiva University, New York, New York 10016, USA
| | - J G Hirsch
- Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apdo. Postal 70-543, C.P. 04510 Cd. Mx., Mexico
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Goncalves Pereira JG, Pires MI, Abreu L, Antunes H, Goncalves ML, Santos JM, Marmelo B, Moreira D, Silverio R, Santos LF, Costa Cabral J. P4206Percutaneous coronary intervention risk models: evaluating accuracy at predicting in-hospital mortality. Eur Heart J 2018. [DOI: 10.1093/eurheartj/ehy563.p4206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
| | - M I Pires
- Hospital Sao Teotonio, Cardiology, Viseu, Portugal
| | - L Abreu
- Hospital Sao Teotonio, Cardiology, Viseu, Portugal
| | - H Antunes
- Hospital Sao Teotonio, Cardiology, Viseu, Portugal
| | | | - J M Santos
- Hospital Sao Teotonio, Cardiology, Viseu, Portugal
| | - B Marmelo
- Hospital Sao Teotonio, Cardiology, Viseu, Portugal
| | - D Moreira
- Hospital Sao Teotonio, Cardiology, Viseu, Portugal
| | - R Silverio
- Hospital Sao Teotonio, Internal Medicine, Viseu, Portugal
| | - L F Santos
- Hospital Sao Teotonio, Cardiology, Viseu, Portugal
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Popa AC, Stan GE, Husanu MA, Mercioniu I, Santos LF, Fernandes HR, Ferreira JMF. Bioglass implant-coating interactions in synthetic physiological fluids with varying degrees of biomimicry. Int J Nanomedicine 2017; 12:683-707. [PMID: 28176941 PMCID: PMC5268334 DOI: 10.2147/ijn.s123236] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Synthetic physiological fluids are currently used as a first in vitro bioactivity assessment for bone grafts. Our understanding about the interactions taking place at the fluid-implant interface has evolved remarkably during the last decade, and does not comply with the traditional International Organization for Standardization/final draft International Standard 23317 protocol in purely inorganic simulated body fluid. The advances in our knowledge point to the need of a true paradigm shift toward testing physiological fluids with enhanced biomimicry and a better understanding of the materials' structure-dissolution behavior. This will contribute to "upgrade" our vision of entire cascades of events taking place at the implant surfaces upon immersion in the testing media or after implantation. Starting from an osteoinductive bioglass composition with the ability to alleviate the oxidative stress, thin bioglass films with different degrees of polymerization were deposited onto titanium substrates. Their biomineralization activity in simulated body fluid and in a series of new inorganic-organic media with increasing biomimicry that more closely simulated the human intercellular environment was compared. A comprehensive range of advanced characterization tools (scanning electron microscopy; grazing-incidence X-ray diffraction; Fourier-transform infrared, micro-Raman, energy-dispersive, X-ray photoelectron, and surface-enhanced laser desorption/ionization time-of-flight mass spectroscopies; and cytocompatibility assays using mesenchymal stem cells) were used. The information gathered is very useful to biologists, biophysicists, clinicians, and material scientists with special interest in teaching and research. By combining all the analyses, we propose herein a step forward toward establishing an improved unified protocol for testing the bioactivity of implant materials.
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Affiliation(s)
- AC Popa
- National Institute of Materials Physics, Măgurele
- Army Centre for Medical Research, Bucharest, Romania
| | - GE Stan
- National Institute of Materials Physics, Măgurele
| | - MA Husanu
- National Institute of Materials Physics, Măgurele
| | - I Mercioniu
- National Institute of Materials Physics, Măgurele
| | - LF Santos
- Centro de Química Estrutural, Instituto Superior Técnico (CQE-IST), University of Lisbon, Lisbon
| | - HR Fernandes
- Department of Materials and Ceramics Engineering, Centre for Research in Ceramics and Composite Materials (CICECO), University of Aveiro, Aveiro, Portugal
| | - JMF Ferreira
- Department of Materials and Ceramics Engineering, Centre for Research in Ceramics and Composite Materials (CICECO), University of Aveiro, Aveiro, Portugal
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Ferreira RV, Serpa D, Machado AI, Rodríguez-Blanco ML, Santos LF, Taboada-Castro MT, Cerqueira MA, Keizer JJ. Short-term nitrogen losses by overland flow in a recently burnt forest area in north-central Portugal: A study at micro-plot scale. Sci Total Environ 2016; 572:1281-1288. [PMID: 26765507 DOI: 10.1016/j.scitotenv.2015.12.042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 12/08/2015] [Accepted: 12/09/2015] [Indexed: 06/05/2023]
Abstract
Over the past decades, wildfires have affected extensive areas of the Mediterranean region with negative impacts on the environment. Most of the studies on fire-affected areas have focused on sediment losses by overland flow, whereas few have addressed post-fire nutrient export. The present study aimed to address this research gap by assessing nitrogen (nitrate and total nitrogen) losses by overland flow in a recently burnt area in north-central Portugal. To this end, three burnt slopes were selected for their contrasting forest types (eucalypt vs. pine) and parent materials (granite vs. schist). The selected study sites were a eucalypt site on granite (BEG), a eucalypt site on schist (BES) and a maritime pine site on schist (BPS). Overland flow samples were collected during the first six months after the wildfire on a 1- to 2-weekly basis, after which this study had to be cancelled due to bench terracing of some of the sites. A peak in total nitrogen concentrations was observed in burnt areas immediately after the first post-fire rainfall event as a response to the erosion of the N-enriched ash layer. After this initial peak, smaller peaks were observed throughout the study period, mainly as a response to overland flow and/or erosion events. Nitrogen export differed strikingly between the two types of forests on schist, being higher at the eucalypt than at the pine site, due to the lack of a protective soil layer. Parent material did not play an important role on nitrogen export by overland flow since no significant differences were found between the eucalypt sites on granite and schist. The present study provides some insight into the differences in post-fire soil fertility losses between forest types and parent materials in the Mediterranean region, which is crucial information for defining post-fire land management measures to reduce soil degradation.
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Affiliation(s)
- R V Ferreira
- CESAM & Department of Environment and Planning, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
| | - D Serpa
- CESAM & Department of Environment and Planning, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.
| | - A I Machado
- CESAM & Department of Environment and Planning, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
| | | | - L F Santos
- CESAM & Department of Environment and Planning, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
| | - M T Taboada-Castro
- Faculty of Sciences, University of A Coruña, A Zapateira, 15008 A Coruña, Spain
| | - M A Cerqueira
- CESAM & Department of Environment and Planning, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
| | - J J Keizer
- CESAM & Department of Environment and Planning, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
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Vieira Ferreira LF, Ferreira DP, Conceição DS, Santos LF, Pereira MFC, Casimiro TM, Ferreira Machado I. Portuguese tin-glazed earthenware from the 17th century. Part 2: A spectroscopic characterization of pigments, glazes and pastes of the three main production centers. Spectrochim Acta A Mol Biomol Spectrosc 2015; 149:285-294. [PMID: 25965511 DOI: 10.1016/j.saa.2015.04.090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 03/26/2015] [Accepted: 04/20/2015] [Indexed: 06/04/2023]
Abstract
Sherds representative of the three Portuguese faience production centers of the 17th century - Lisbon, Coimbra and Vila Nova were studied with the use of mostly non-invasive spectroscopies, namely: ground state diffuse reflectance absorption (GSDR), micro-Raman, Fourier-transform infrared (FT-IR) and proton induced X-ray (PIXE) or X-ray fluorescence emission (XRF). X-ray diffraction (XRD) experiments were also performed. The obtained results evidence a clear similarity in the pastes of the pottery produced Vila Nova and some of the ceramic pastes from Lisbon, in accordance with documental sources that described the use of Lisbon clays by Vila Nova potters, at least since mid 17th century. Quartz and Gehlenite are the main components of the Lisbon's pastes, but differences between the ceramic pastes were detected pointing out to the use of several clay sources. The spectroscopic trend exhibited Coimbra's pottery is remarkably different, Quartz and Diopside being the major components of these pastes, enabling one to well define a pattern for these ceramic bodies. The blue pigment from the Lisbon samples is a cobalt oxide that exists in the silicate glassy matrix, which enables the formation of detectable cobalt silicate microcrystals in most productions of the second half of the 17th century. No micro-Raman cobalt blue signature could be detected in the Vila Nova and Coimbra blue glazes. This is in accordance with the lower kiln temperatures in these two production centers and with Co(2+) ions dispersed in the silicate matrix. In all cases the white glaze is obtained with the use of tin oxide. Hausmannite was detected as the manganese oxide mineral used to produce the purple glaze (wine color "vinoso") in Lisbon.
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Affiliation(s)
- L F Vieira Ferreira
- CQFM - Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
| | - D P Ferreira
- CQFM - Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - D S Conceição
- CQFM - Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - L F Santos
- Departamento Engenharia Química and ICEMS, Instituto Superior Técnico Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - M F C Pereira
- CEPGIST - Centro de Petrologia e Geoquímica/CERENA - Centro de Estudos em Recursos Naturais e Ambiente, Instituto Superior Técnico Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - T M Casimiro
- Instituto de Arqueologia e Paleociências da Universidade Nova de Lisboa, Departamento de História, Avenida de Berna 26-C, 1069-061 Lisboa, Portugal
| | - I Ferreira Machado
- CQFM - Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; Department of Technology and Design, School of Technology and Management, Polytechnic Institute of Portalegre, P-7300-110 Portalegre, Portugal
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Santos LF, Borgonovi F, Izrailev FM. Chaos and statistical relaxation in quantum systems of interacting particles. Phys Rev Lett 2012; 108:094102. [PMID: 22463641 DOI: 10.1103/physrevlett.108.094102] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Indexed: 05/31/2023]
Abstract
We study the transition to chaos and the emergence of statistical relaxation in isolated dynamical quantum systems of interacting particles. Our approach is based on the concept of delocalization of the eigenstates in the energy shell, controlled by the Gaussian form of the strength function. We show that, although the fluctuations of the energy levels in integrable and nonintegrable systems are different, the global properties of the eigenstates are quite similar, provided the interaction between particles exceeds some critical value. In this case, the statistical relaxation of the systems is comparable, irrespective of whether or not they are integrable. The numerical data for the quench dynamics manifest excellent agreement with analytical predictions of the theory developed for systems of two-body interactions with a completely random character.
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Affiliation(s)
- L F Santos
- Department of Physics, Yeshiva University, 245 Lexington Avenue, New York, New York 10016, USA.
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Santos LF, Borgonovi F, Izrailev FM. Onset of chaos and relaxation in isolated systems of interacting spins: energy shell approach. Phys Rev E Stat Nonlin Soft Matter Phys 2012; 85:036209. [PMID: 22587163 DOI: 10.1103/physreve.85.036209] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2011] [Indexed: 05/16/2023]
Abstract
We study the onset of chaos and statistical relaxation in two isolated dynamical quantum systems of interacting spins 1/2, one of which is integrable and the other chaotic. Our approach to identifying the emergence of chaos is based on the level of delocalization of the eigenstates with respect to the energy shell, the latter being determined by the interaction strength between particles or quasiparticles. We also discuss how the onset of chaos may be anticipated by a careful analysis of the Hamiltonian matrices, even before diagonalization. We find that despite differences between the two models, their relaxation processes following a quench are very similar and can be described analytically with a theory previously developed for systems with two-body random interactions. Our results imply that global features of statistical relaxation depend on the degree of spread of the eigenstates within the energy shell and may happen to both integrable and nonintegrable systems.
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Affiliation(s)
- L F Santos
- Department of Physics, Yeshiva University, 245 Lexington Avenue, New York, New York 10016, USA.
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Vilela Filho O, Silva DJ, Souza HA, Cavalcante JE, Sousa JT, Ferraz FP, Silva LG, Santos LF. Stereotactic subthalamic nucleus lesioning for the treatment of Parkinson's disease. Stereotact Funct Neurosurg 2002; 77:79-86. [PMID: 12378061 DOI: 10.1159/000064601] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
This study was performed to evaluate the effectiveness and safety of unilateral STN lesioning in 23 patients with PD. L-Dopa intake and dyskinesia, Hoehn & Yahr, Schwab & England, and UPDRS motor scores were recorded pre- and postoperatively. Stereotactic MRI and CT and macrostimulation were used to establish target coordinates. A single RF lesion was performed. All patients underwent postoperative MRI. Contralateral tremor arrest and decrease of rigidity and bradykinesia should be regarded as hallmarks to STN stimulation. All recorded parameters were significantly improved after a mean follow-up of 13.5 months. Patients with STN lateral territory lesioning (alpha <0.05), younger than 61 years and with a duration of the disease between 6 and 9 years (alpha >0.05) did better than the others. The recurrence rate was 10%. Two patients developed dyskinesias which were completely resolved by a Vim/VOp lesion. Other significant complications were rare. The authors conclude that unilateral STN lesioning is a safe and very effective procedure to treat PD.
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Affiliation(s)
- O Vilela Filho
- Stereotactic and Functional Neurosurgery Service and Parkinson's Disease and Movement Disorders Unity, Hospital das Clínicas, Medical School, Universidade Federal de Goiás, Brazil.
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Rosa JS, Johnson EH, Alves FS, Santos LF. A retrospective study of hepatic abscesses in goats: pathological and microbiological findings. Br Vet J 1989; 145:73-6. [PMID: 2920279 DOI: 10.1016/0007-1935(89)90012-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Post-mortem examination of 658 goats showed that 17 (2.5%) exhibited hepatic abscesses. The following bacteria were isolated: Corynebacterium pseudotuberculosis (58.9%), Escherichia coli (11.8%), Corynebacterium sp. (11.8%), Pasteurella haemolytica (5.9%), Proteus sp. (5.9%) and Staphylococcus aureus (5.9%). Hepatic abscesses occurred more frequently in adult animals. Eleven of the 17 goats (64.7%) were older than 12 months of age. Four goats (23.5%) were 12 months of age and only two (11.8%) were less than 1 year of age. All of the goats with hepatic abscesses were in poor nutritional condition and the abscesses were invariably associated with accompanying pathological disorders at other body sites.
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