Empirical Saturation Research Articles

What do people do before going to the dentist? Qualitative study of cultural practices of pain relief in primary care.

Objective: To describe and classify the main cultural practices used to relieve orodental pain in people who seek emergency dental care in vulnerable urban and rural areas of central Chile. Methodology: A sample of 88 adults residing in urban and rural sectors, who received treatment at primary care emergency dental services in three districts of the central area of Chile was studied using a qualitative descriptive approach of sociocultural epidemiological orientation based on Grounded Theory. Interviews were conducted in the waiting room of the emergency service or at the patient’s home. Empirical saturation and triangulation of temporal data were protected. Results: Practices of biomedical origin (self-medication and care received at dental emergency services) and socio-cultural practices were documented. They include the use of chemical products (iodine, phosphorus, battery acid, hydrogen peroxide, gasoline, and alcoholic drinks, among others), herbal infusions (Buddleja globosa, Aloe vera), mechanical-physical techniques (use of cold or heat, massage); subjects also perform the mechanical manipulation of the area with sharp objects, occasionally extracting the tooth itself. Practices occur more frequently at home when the person feels the pain in the affected area, and end on the dental chair with the tooth extraction. Conclusions: The coexistence of biomedical practices and alternative cultural strategies was observed. These practices complement each other and make people postpone seeking professional dental care, which may worsen their health condition.

Probabilistic inference of ecohydrological parameters using observations from point to satellite scales

Abstract. Vegetation controls on soil moisture dynamics are challenging to measure and translate into scale- and site-specific ecohydrological parameters for simple soil water balance models. We hypothesize that empirical probability density functions (pdfs) of relative soil moisture or soil saturation encode sufficient information to determine these ecohydrological parameters. Further, these parameters can be estimated through inverse modeling of the analytical equation for soil saturation pdfs, derived from the commonly used stochastic soil water balance framework. We developed a generalizable Bayesian inference framework to estimate ecohydrological parameters consistent with empirical soil saturation pdfs derived from observations at point, footprint, and satellite scales. We applied the inference method to four sites with different land cover and climate assuming (i) an annual rainfall pattern and (ii) a wet season rainfall pattern with a dry season of negligible rainfall. The Nash–Sutcliffe efficiencies of the analytical model's fit to soil observations ranged from 0.89 to 0.99. The coefficient of variation of posterior parameter distributions ranged from < 1 to 15 %. The parameter identifiability was not significantly improved in the more complex seasonal model; however, small differences in parameter values indicate that the annual model may have absorbed dry season dynamics. Parameter estimates were most constrained for scales and locations at which soil water dynamics are more sensitive to the fitted ecohydrological parameters of interest. In these cases, model inversion converged more slowly but ultimately provided better goodness of fit and lower uncertainty. Results were robust using as few as 100 daily observations randomly sampled from the full records, demonstrating the advantage of analyzing soil saturation pdfs instead of time series to estimate ecohydrological parameters from sparse records. Our work combines modeling and empirical approaches in ecohydrology and provides a simple framework to obtain scale- and site-specific analytical descriptions of soil moisture dynamics consistent with soil moisture observations.

Gütekriterien qualitativer Sozialforschung. Ein Diskussionsanstoß

ZusammenfassungDer Beitrag expliziert Gütekriterien der qualitativen Sozialforschung. Er geht von der Prämisse aus, dass Qualitätsmerkmale in diesem Segment empirischer Sozialforschung nur unter konsequentem Rekurs auf die spezifischen Funktionsbedingungen interpretativer und rekonstruktiver Verfahren zu bestimmen sind. Fünf Kriterien werden vorgeschlagen:Gegenstandsangemessenist eine Weise der Herstellung des Forschungsgegenstandes, die das empirische Feld ernst nimmt und Methoden, Fragestellungen und Datentypen einer fortlaufenden Justierungsanforderung unterwirft.Empirische Sättigungreflektiert die Güte der Verankerung von Interpretationen im Datenmaterial.Theoretische Durchdringungmarkiert die Qualität der Theoriebezüge, in die das Forschen eingespannt ist, und arbeitet an deren Irritationspotential.Textuelle Performanzbezeichnet die Leistung, die Texte als Güte konstituierende Kommunikation gegenüber Rezipientinnen der Forschung zu erbringen haben.Originalitätschließlichist das Kriterium, an dem die Einlösung des Neuigkeitsanspruchs wissenschaftlichen Wissens zu prüfen ist.

Effects of the nucleon radius on neutron stars in a quark mean field model

We study the effects of free space nucleon radius on nuclear matter and neutron stars within the framework of quark mean field model. The nucleon radius is treated self-consistently with this model, where quark confinement is adjusted to fit different values of nucleon radius. Corrections due to center-of-mass motion, quark-pion coupling, and one gluon exchange are included to obtain the nucleon mass in vacuum. The meson coupling constants that describe the behavior of many-body nucleonic system are newly-constructed by reproducing the empirical saturation properties of nuclear matter, including the recent determinations of symmetry energy parameters. Our results show that the nucleon radius in free space have negligible effects on nuclear matter equation of state and neutron star mass-radius relations, which is different from the conclusion drawn in previous studies. We further explore that the sensitivity of star radius on the nucleon radius found in earlier publications is actually from the symmetry energy and its slope.

Archie's Saturation Exponent for Natural Gas Hydrate in Coarse‐Grained Reservoirs

AbstractAccurately quantifying the amount of naturally occurring gas hydrate in marine and permafrost environments is important for assessing its resource potential and understanding the role of gas hydrate in the global carbon cycle. Electrical resistivity well logs are often used to calculate gas hydrate saturations, Sh, using Archie's equation. Archie's equation, in turn, relies on an empirical saturation parameter, n. Though n = 1.9 has been measured for ice‐bearing sands and is widely used within the hydrate community, it is highly questionable if this n value is appropriate for hydrate‐bearing sands. In this work, we calibrate n for hydrate‐bearing sands from the Canadian permafrost gas hydrate research well, Mallik 5L‐38, by establishing an independent downhole Sh profile based on compressional‐wave velocity log data. Using the independently determined Sh profile and colocated electrical resistivity and bulk density logs, Archie's saturation equation is solved for n, and uncertainty is tracked throughout the iterative process. In addition to the Mallik 5L‐38 well, we also apply this method to two marine, coarse‐grained reservoirs from the northern Gulf of Mexico Gas Hydrate Joint Industry Project: Walker Ridge 313‐H and Green Canyon 955‐H. All locations yield similar results, each suggesting n ≈ 2.5 ± 0.5. Thus, for the coarse‐grained hydrate bearing (Sh > 0.4) of greatest interest as potential energy resources, we suggest that n = 2.5 ± 0.5 should be applied in Archie's equation for either marine or permafrost gas hydrate settings if independent estimates of n are not available.

Equation of state of dense nuclear matter and neutron star structure from nuclear chiral interactions

Aims. We report a new microscopic equation of state (EOS) of dense symmetric nuclear matter, pure neutron matter, and asymmetric and β-stable nuclear matter at zero temperature using recent realistic two-body and three-body nuclear interactions derived in the framework of chiral perturbation theory (ChPT) and including the Δ(1232) isobar intermediate state. This EOS is provided in tabular form and in parametrized form ready for use in numerical general relativity simulations of binary neutron star merging. Here we use our new EOS for β-stable nuclear matter to compute various structural properties of non-rotating neutron stars. Methods. The EOS is derived using the Brueckner–Bethe–Goldstone quantum many-body theory in the Brueckner–Hartree–Fock approximation. Neutron star properties are next computed solving numerically the Tolman–Oppenheimer–Volkov structure equations. Results. Our EOS models are able to reproduce the empirical saturation point of symmetric nuclear matter, the symmetry energy Esym, and its slope parameter L at the empirical saturation density n0. In addition, our EOS models are compatible with experimental data from collisions between heavy nuclei at energies ranging from a few tens of MeV up to several hundreds of MeV per nucleon. These experiments provide a selective test for constraining the nuclear EOS up to ~4n0. Our EOS models are consistent with present measured neutron star masses and particularly with the mass M = 2.01 ± 0.04 M⊙ of the neutron stars in PSR J0348+0432.

Temperature Effects on the Equation of State and Symmetry Energy: A Critique

The investigation of strongly interacting systems ranges from matter inside atomic nuclei to matter under extreme conditions in astrophysics. These systems require the introduction of nuclear forces and a systematic many-body approach to solve the strong interaction particles. Understanding the behavior of infinite nuclear matter provides a path to predict the properties of neutron stars and gives insights to astrophysical phenomena. Three-nucleon forces have to be considered when studying nuclear systems, because their impact is necessary to reproduce properties of nuclei and to correctly obtain the neutron drip line. Moreover, they are needed to predict the empirical saturation properties of infinite nuclear matter. The self-consistent Green’s Function approach paves the way for an improved Ab initio analysis of nuclear matter, thereby providing the basis for the equation of state of neutron stars and supernova explosions.

Application of an empirical saturation rule to TGLF to unify low-k and high-k turbulence dominated regimes

We propose a phenomenological turbulence saturation model and apply it to the TGLF turbulence transport model (Staebler et al 2007 Phys. Plasmas 14 055909), which captures the physics of interaction between low-k and high-k turbulence consistent with the multi-scale gyro-kinetic simulation result reported by Howard (2016 Nucl. Fusion. 23 056109). The new model, TGLF-Vx is tested with three discharges from DIII-D and EAST tokamak, which cover both low-k and high-k turbulence dominated regimes. It is found that the profile match can be substantially improved over previous models when evolving Te, Ti and ne simultaneously. Good agreement for all three discharges is obtained with one fixed parameter in the model when taking experimental uncertainties into consideration. Lastly, TGLF-Vx is applied to explore the sensitivity of the predicted CFETR steady-state performance to different transport models. Our result shows that a scenario using only RF auxiliary heating could be significantly affected.

Effect of tensor correlations on the depletion of nuclear Fermi sea within the extended BHF approach**Supported by National Natural Science Foundation of China (11435014, 11175219), the 973 Program of China (2013CB834405) and the Knowledge Innovation Project (KJCX2-EW-N01) of the Chinese Academy of Sciences

We have investigated the effect of tensor correlations on the depletion of the nuclear Fermi sea in symmetric nuclear matter within the framework of the extended Brueckner-Hartree-Fock approach by adopting the AV 18 two-body interaction and a microscopic three-body force. The contributions from various partial wave channels including the isospin-singlet T=0 channel, the isospin-triplet T=1 channel and the T=0 tensor 3SD1 channel have been calculated. The T=0 neutron-proton correlations play a dominant role in causing the depletion of nuclear Fermi sea. The T=0 correlation-induced depletion turns out to stem almost completely from the 3SD1 tensor channel. The isospin-singlet T=0 3SD1 tensor correlations are shown to be responsible for most of the depletion, which amounts to more than 70 percent of the total depletion in the density region considered. The three-body force turns out to lead to an enhancement of the depletion at high densities well above the empirical saturation density and its effect increases as a function of density.

Convergence of the hole-line expansion with modern nucleon-nucleon potentials

The accurate computation of nuclear matter properties, such as its binding energy, is still a challenge to nuclear theory, largely because the quark substructure of nucleons creates a strong repulsion at short distances that renders a straightforward perturbative calculation impossible. In this work, the authors study the Brueckner-Bethe-Goldstone expansion of dense Fermi systems in terms of hole-line contributions, of the associated Goldstone diagrams, to the binding energy of nuclear matter. They use various modern nucleon-nucleon potentials of high precision. In all cases the three-hole-line contributions are sufficiently small suggesting that the expansion converges. Yet, the empirical saturation properties of nuclear matter are not reproduced for any potential. This means that very strong nuclear three-body forces are required in order to achieve satisfactory saturation properties of nuclear matter, and that such forces are essential for all considered potentials.

FORMAÇÃO E INTERVENÇÃO PROFISSIONAL EM SAÚDE PÚBLICA: PERCEPÇÕES DE PROFISSIONAIS DE EDUCAÇÃO FÍSICA

Neste artigo buscamos analisar as percepções de profissionais de Educação Física sobre os processos de formação e seus reflexos na atuação em serviços da Saúde Pública em Goiânia/GO. Realizamos entrevistas com nove trabalhadores de quatro instituições da Secretaria Municipal de Saúde desta cidade. O material coletado foi analisado a partir da técnica de Análise de Conteúdo, com apoio do software Webqda. O rigor empregado na sistematização dos dados se deu pelo uso da técnica de saturação teórica e empírica. Os resultados apontaram que os profissionais veem a formação inicial: tradicional e tecnicista; mais centrada no campo da iniciação esportiva, atividade física, exercícios físicos, escola/didática e da academia de ginástica; e pouco focada nas necessidades dos serviços públicos de saúde, gerando fragilidade nesta dimensão da intervenção profissional.

The Thermal Properties of Asymmetric Nuclear Matter within the Extended Brueckner–Hartree–Fock Approach

The single-particle potentials and other properties at absolute zero temperature in isospin asymmetric nuclear matter are investigated in the frame of an extended Brueckner theory. Also thermal quantities are calculated in asymmetric nuclear matter using CD-Bonn potential and the Urbana three-body forces (3BF). Also, the effects of the hole–hole contributions are investigated within the self-consistent Greens function approach. The inclusion of 3BF or the hole–hole contributions improves the predicted saturation property of symmetric nuclear matter within the Brueckner–Hartree–Fock approach and it leads to a significant stiffening of the density dependence of symmetry energy at high densities but the exact saturation point is not reproduced. This is of great importance in astrophysical calculation. A phenomenological term simulating the three-body interaction is introduced to assure the empirical saturation property. The hot properties of asymmetric nuclear matter such as the internal energy and the press...

Nuclear charge and neutron radii and nuclear matter: Trend analysis in Skyrme density-functional-theory approach

Radii of charge and neutron distributions are fundamental nuclear properties. They depend on both nuclear interaction parameters related to the equation of state of infinite nuclear matter and on quantal shell effects, which are strongly impacted by the presence of nuclear surface. In this work, by studying the dependence of charge and neutron radii, and neutron skin, on nuclear matter parameters, we assess different mechanisms that drive nuclear sizes. We apply nuclear density functional theory using a family of Skyrme functionals obtained by means of different optimization protocols targeting specific nuclear properties. By performing the Monte-Carlo sampling of reasonable functionals around the optimal parametrization, we study correlations between nuclear matter paramaters and observables characterizing charge and neutron distributions. We demonstrate the existence of the strong converse relation between the nuclear charge radii and the saturation density of symmetric nuclear matter and also between the neutron skins and the slope of the symmetry energy. For functionals optimized to experimental binding energies only, proton and neutron radii are weakly correlated due to canceling trends from different nuclear matter parameters. We show that by requiring that the nuclear functional reproduces the empirical saturation point of symmetric nuclear matter practically fixes the charge (or proton) radii, and vice versa. The neutron skin uncertainty primarily depends on the slope of the symmetry energy. Consequently, imposing a constraint on both $\rho_0$ and $L$ practically determines the nuclear size, modulo small variations due to shell effects.

A further update on possible crises in nuclear-matter theory

The ancient problem of the saturation of symmetric nuclear matter is reviewed with an update on the status of the crises that were identified at an early stage by John Clark. We discuss how the initial problem with variational calculations providing more binding than the two hole-line contribution for the same interaction was overcome by calculations including three hole-line contributions without however reproducing the empirical nuclear saturation properties. It is argued that this remaining problem is still open because many solutions have been proposed or ad hoc adjustments implemented without generating universal agreement on the proper interpretation of the physics. The problem of nuclear saturation therefore persists leading to the necessity of an analysis of the way the nuclear saturation properties are obtained from experimental data. We clarify the role of short-range correlations and review results for nuclear saturation when such ingredients are completely taken into account using the Green’s function method. The role of long-range correlations is then analyzed with special emphasis on the importance of attractive pion-dominated excitation modes which inevitably lead to higher saturation densities than observed. Because such modes have no counterpart in finite nuclear systems, it is therefore argued that they should not be considered when calculating nuclear matter properties. The remaining open question is then whether long-range correlations in finite nuclei which in turn have no counterpart in infinite matter, represent the remaining missing ingredient in this analysis. We also briefly comment on the role of three-body interactions in the context of the dispersive optical model description of experimental data. It is further noted that interactions based on chiral perturbation theory at present do not generate a sufficient number of high-momentum nucleons leading to radii that are too small and substantial overbinding in finite nuclei.

Three-body force effect on the properties of neutron-rich nuclear matter

We review our research work on the single-particle properties and the equation of state (EOS) of isospin asymmetric nuclear matter within the framework of the Brueckner-Hartree-Fock (BHF) approach extended by including a microscopic three-body force (TBF). The TBF is shown to affect significantly the nuclear matter EOS and the density dependence of nuclear symmetry energy at high densities above the normal nuclear matter density, and it is necessary for reproducing the empirical saturation property of symmetric nuclear matter in a nonrelativistic microscopic framework. The TBF-induced rearrangement effect and the ground state (g.s.) correlation effect on the s.p. properties in neutron-rich nuclear matter are investigated. Both effects turn out to be crucial for predicting reliably the s.p. properties within the Brueckner framework. The TBF effect on nucleon superfluidity in neutron star matter and neutron stars has also been discussed.

Equation of State and Symmetry Energy at High Densities for Zero and Finite Temperatures

The equation of state of isospin asymmetric nuclear matter within the framework of the Brueckner theory is used to calculate the energy per particle for nuclear and neutron matter. Pressure and symmetry energy are also presented. Here we extended our work to include Skyrme-like zero-range density-dependent two-body forces, which could mimic three-body forces. A three-body forces are shown to be necessary for reproducing the empirical saturation properties of symmetric nuclear matter. We also studied the effect of extending the calculation to finite temperatures.

Relativistic effects in three-nucleon forces for nuclear matter and finite nuclei

In order to simulate the relativistic effects of the Dirac-Brueckner-Hartree-Fock approach for finite nuclei, the part of the Urbana three-nucleon (3N) force is considered, which represents the enhancement of the small components of the Dirac spinors for the nucleons in the nuclear medium. This 3N force is included in a Brueckner-Hartree-Fock calculation with rearrangement terms using a realistic model for the NN interaction. The strength of the 3N force is adjusted to reproduce the empirical saturation point of nuclear matter and then used in corresponding studies of the closed shell nuclei $^{16}\mathrm{O}$ and $^{40}\mathrm{Ca}$. Special attention is paid to a consistent treatment of the spectrum of particle states in the NN propagator of the Bethe-Goldstone equation.

Skyrme interaction to second order in nuclear matter

Based on the phenomenological Skyrme interaction various density-dependent nuclear matter quantities are calculated up to second order in many-body perturbation theory. The spin–orbit term as well as two tensor terms contribute at second order to the energy per particle. The simultaneous calculation of the isotropic Fermi-liquid parameters provides a rigorous check through the validity of the Landau relations. It is found that published results for these second order contributions are incorrect in most cases. In particular, interference terms between s-wave and p-wave components of the interaction can contribute only to (isospin or spin) asymmetry energies. Even with nine adjustable parameters, one does not obtain a good description of the empirical nuclear matter saturation curve in the low density region . The reason for this feature is the too strong density-dependence of several second-order contributions. The inclusion of the density-dependent term is therefore indispensable for a realistic description of nuclear matter in the Skyrme framework.

Comparative study of three-nucleon force models in nuclear matter

We calculate the energy per particle of symmetric nuclear matter and pure neutron matter using the microscopic many-body Brueckner-Hartree-Fock (BHF) approach and employing the Argonne V18 (AV18) nucleon-nucleon (NN) potential supplemented with two different three-nucleon force models recently constructed to reproduce the binding energy of $^{3}\mathrm{H},\phantom{\rule{0.16em}{0ex}}^{3}\mathrm{He}$, and $^{4}\mathrm{He}$ nuclei as well as the neutron-deuteron doublet scattering length. We find that none of these new three-nucleon force models is able to reproduce simultaneously the empirical saturation point of symmetric nuclear matter and the properties of three- and four-nucleon systems.

Accurate nuclear radii and binding energies from a chiral interaction

With the goal of developing predictive ab-initio capability for light and medium-mass nuclei, two-nucleon and three-nucleon forces from chiral effective field theory are optimized simultaneously to low-energy nucleon-nucleon scattering data, as well as binding energies and radii of few-nucleon systems and selected isotopes of carbon and oxygen. Coupled-cluster calculations based on this interaction, named NNLO$_{\rm sat}$, yield accurate binding energies and radii of nuclei up to $^{40}$Ca, and are consistent with the empirical saturation point of symmetric nuclear matter. In addition, the low-lying collective $J^\pi=3^-$ states in $^{16}$O and $^{40}$Ca are described accurately, while spectra for selected $p$- and $sd$-shell nuclei are in reasonable agreement with experiment.