Misleading signatures of quantum chaos

The main signature of chaos in a quantum system is provided by spectral statistical analysis of the nearest neighbor spacing distribution and the spectral rigidity given by $\Delta_3(L)$. It is shown that some standard unfolding procedures, like local unfolding and Gaussian broadening, lead to a spurious increase of the spectral rigidity that spoils the $\Delta_3(L)$ relationship with the regular or chaotic motion of the system. This effect can also be misinterpreted as Berry's saturation.Comment: 4 pages, 5 figures, submitted to Physical Review

Particle-drip lines from the Hartree-Fock-Bogoliubov theory with Skyrme interaction

We calculate positions of one- and two-particle, proton and neutron drip lines within the Hartree-Fock-Bogoliubov theory using Skyrme interaction. We also determine an approximate $r$-process path defined as a line where the neutron binding energy is equal to 2~MeV. A weakening of the nuclear shell structure at drip lines is found and interpreted as resulting from a coupling with continuum states.Comment: 10 pages REVTEX 3.0, 3 uuencoded postscript figures included, IFT/14/9

Spectral fluctuation properties of spherical nuclei

The spectral fluctuation properties of spherical nuclei are considered by use of NNSD statistic. With employing a generalized Brody distribution included Poisson, GOE and GUE limits and also MLE technique, the chaoticity parameters are estimated for sequences prepared by all the available empirical data. The ML-based estimated values and also KLD measures propose a non regular dynamic. Also, spherical odd-mass nuclei in the mass region, exhibit a slight deviation to the GUE spectral statistics rather than the GOE.Comment: 10 pages, 2 figure

Quantum Chaos in A=46--50 Atomic Nuclei

The spectral statistics of low--lying states of several $fp$ shell nuclei are studied with realistic shell--model calculations. For Ca isotopes, we find significant deviations from the predictions of the random--matrix theory which suggest that some spherical nuclei are not as chaotic in nature as the conventional view assumes.Comment: 12 pages, LaTex, 2 figures available upon request, to be published in Physics Letters

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Examination of experimental evidence of chaos in the bound states of Pb 208

7 pags., 3 figs., tab., app.We study the spectral fluctuations of the Pb208 nucleus using the complete experimental spectrum of 151 states up to excitation energies of 6.20 MeV recently identified at the Maier-Leibnitz Laboratorium at Garching, Germany. For natural parity states the results are very close to the predictions of random matrix theory (RMT) for the nearest-neighbor spacing distribution. A quantitative estimate of the agreement is given by the Brody parameter ω, which takes the value ω=0 for regular systems and ω≃1 for chaotic systems. We obtain ω=0.85 which is, to our knowledge, the closest value to chaos ever observed in experimental bound states of nuclei. By contrast, the results for unnatural parity states are far from RMT behavior. We interpret these results as a consequence of the strength of the residual interaction in Pb208, which, according to experimental data, is much stronger for natural than for unnatural parity states. In addition, our results show that chaotic and nonchaotic nuclear states coexist in the same energy region of the spectrum.This research was conducted with support of Spanish Ministry of Science and Innovation GrantsNo. FIS2012-35316 and No. FIS2012-34479, MINECO/FEDER Grant No. FIS2015- 63770-P, and CAM research consortium QUITEMAD+ S2013/ICE-2801Peer Reviewe

Localization in 2p1f nuclear shell-model wavefunctions

8 pages, 1 table, 4 figures.--PACS nrs.: 21.60.Cs; 21.10.Pc; 24.60.Lz.--Printed version published Aug 14, 2003.For the study of complexity and chaos in many-particle nuclear wavefunctions in large shell-model basis spaces, the localization length related to the number of principal components is calculated for several Ca, Sc and Ti isotopes, and compared to the predictions of the embedded Gaussian orthogonal ensemble. The large dimensionalities involved, up to many thousands, ensure good statistics, and the agreement is very good in the chaotic region of the spectra. The localization length of shellmodel wavefunctions in Ca isotopes is much smaller than in Sc, showing a strong isospin dependence of nuclear chaos, in good agreement with previous results based on energy level fluctuation properties.This work was supported in part by Spanish Government grants No. DGI-BFM2000-0600 and DGIFTN2000-0963-C02-01.Peer reviewe

Localization in 2p1f nuclear shell-model wavefunctions

AbstractFor the study of complexity and chaos in many-particle nuclear wavefunctions in large shell-model basis spaces, the localization length related to the number of principal components is calculated for several Ca, Sc and Ti isotopes, and compared to the predictions of the embedded Gaussian orthogonal ensemble. The large dimensionalities involved, up to many thousands, ensure good statistics, and the agreement is very good in the chaotic region of the spectra. The localization length of shell-model wavefunctions in Ca isotopes is much smaller than in Sc, showing a strong isospin dependence of nuclear chaos, in good agreement with previous results based on energy level fluctuation properties

Recent results on quantum chaos and its applications to atomic nuclei.

A survey of chaotic dynamics in atomic nuclei is presented, using on the one hand standard statistics of quantum chaos studies, and on the other a new approach based on time series analysis methods. The study of shell-model spectra in the pf shell shows that nuclear chaos is strongly isopin dependent and increases with excitation energy. On the other hand, it is found that chaotic quantum systems exhibit 1/f noise and regular systems exhibit 1/f 2 behaviour. It is shown that the time series approach can be used to calculate quite accurately the fraction of missing levels and the existence of mixed symmetries in experimental level spectra.Peer Reviewe