Neutron matter at low density and the unitary limit

Neutron matter at low density is studied within the hole-line expansion. Calculations are performed in the range of Fermi momentum $k_F$ between 0.4 and 0.8 fm$^{-1}$. It is found that the Equation of State is determined by the $^1S_0$ channel only, the three-body forces contribution is quite small, the effect of the single particle potential is negligible and the three hole-line contribution is below 5% of the total energy and indeed vanishing small at the lowest densities. Despite the unitary limit is actually never reached, the total energy stays very close to one half of the free gas value throughout the considered density range. A rank one separable representation of the bare NN interaction, which reproduces the physical scattering length and effective range, gives results almost indistinguishable from the full Brueckner G-matrix calculations with a realistic force. The extension of the calculations below $k_F = 0.4$ fm$^{-1}$ does not indicate any pathological behavior of the neutron Equation of State.Comment: 17 pages, 7 figures. To be published in Phys. Rev.

Non-locality in the nucleon-nucleon interaction and nuclear matter saturation

We study the possible relationship between the saturation properties of nuclear matter and the inclusion of non-locality in the nucleon-nucleon interaction. To this purpose we compute the saturation curve of nuclear matter within the Bethe-Brueckner-Goldstone theory using a recently proposed realistic non-local potential, and compare it with the corresponding curves obtained with a purely local realistic interaction (Argonne v$_{18}$) and the most recent version of the one-boson exchange potential (CD Bonn). We find that the inclusion of non-locality in the two-nucleon bare interaction strongly affects saturation, but it is unable to provide a consistent description of few-body nuclear systems and nuclear matter.Comment: 9 pages, 8 figures; v2: introduction extended, references added, discussion of fig.8 reformulated; to be published in Phys. Rev.

Spin-orbit correlation energy in neutron matter

We study the relevance of the energy correlation produced by the two-body spin-orbit coupling present in realistic nucleon-nucleon potentials. To this purpose, the neutron matter Equation of State (EoS) is calculated with the realistic two-body Argonne $v_8'$ potential. The shift occuring in the EoS when spin-orbit terms are removed is taken as an estimate of the spin-orbit correlation energy. Results obtained within the Bethe-Brueckner-Goldstone expansion, extended up to three hole-line diagrams, are compared with other many-body calculations recently presented in the literature. In particular, excellent agreement is found with the Green's function Monte-Carlo method. This agreement indicates the present theoretical accuracy in the calculation of the neutron matter EoS.Comment: 5 pages, 2 figures, 2 tables; to appear in Phys. Rev.

Telemedicine in chronic disease management: a Public Health perspective

Introduction In 2014, the School of Hygiene of the University of Padua carried out an evaluation of home telemonitoring (HTM) programs for the management of chronic diseases. Our aims were to verify their efficacy, and to identify a model of care that could be integrated into the current health system. Our analysis addressed both organizational and clinical matters. Methods Our evaluation involved 19 reviews and 53 randomized controlled trials (RCT). Main selection criteria were: papers published over the last 15 years, HTM performed through a sensor system, data sent remotely to physicians, health out-comes and monitored parameters clearly stated. Included diseases were: heart failure, hypertension, COPD, asthma and diabetes. Results Several critical issues were highlighted. Due to the general tendency in the scientific literature to report HTM efficacy, there is a lack of conclusive evidence whether telemedicine actually improves both clinical (e.g. decreased disease/all-cause mortality, drop in disease/all-cause hospitalization rates, improvement in biological parameters and quality of life) and organizational (decreased length of hospital stay, decreased emergency room/other service use, decreased costs) outcomes or not. Discussion From a Public Health perspective, discrepancies and weaknesses may affect published results, since the best method for organizing and delivering telemedicine programs has not yet been identified. There is still no consensus on the following topics: setting: which context expresses the potential of technology best? No studies were found comparing, e.g., rural with urban communities. Within urban scenarios, samples do not discriminate users by their capability to access the healthcare network (e.g. residents in peripheral areas with limited transportation resources, rather than users with reduced mobility); target: it is unclear which demographic or socioeconomic characteristics users should possess to gain most benefit from HTM; duration and frequency: there are significant differences in RCT (and HTM program) duration. It has not been established whether HTM is more effective when permanently implemented, or only in the early stages of disease (i.e. until stabilization). There is no agreement on the optimal HTM implementation frequency, nor whether the patients should also receive traditional interventions (e.g. nurse home visits);scope: it has not been determined whether measurements should be disclosed to patients as educational means to improve disease management. However, past literature does include some indications that the effectiveness of HTM programs may be attributable to care intensification (or to a perceived intensification by the patient, as per the \u201cHawthorne effect\u201d described in sociology) or to the empowerment process. Conclusions HTM management of chronic diseases is a promising and remarkable strategy, still flawed by the lack of evidence. Reported efficacy, although modest, probably has a multifactorial origin. Our hypothesis is that it may not result from the technology itself, but from the impact of such process on multiple components of care, emphasizing patients' involvement and autonomy, and improving monitoring intensity. Further studies are needed to clarify the role played by the different HTM components (target, setting, etc.). The application of HTM as a tool for prevention, empowerment and reduction of healthcare access remains little explored

Temperature dependence of single-particle properties in nuclear matter

The single-nucleon potential in hot nuclear matter is investigated in the framework of the Brueckner theory by adopting the realistic Argonne V18 or Nijmegen 93 two-body nucleon-nucleon interaction supplemented by a microscopic three-body force. The rearrangement contribution to the single-particle potential induced by the ground state correlations is calculated in terms of the hole-line expansion of the mass operator and provides a significant repulsive contribution in the low-momentum region around and below the Fermi surface. Increasing temperature leads to a reduction of the effect, while increasing density makes it become stronger. The three-body force suppresses somewhat the ground state correlations due to its strong short-range repulsion, increasing with density. Inclusion of the three-body force contribution results in a quite different temperature dependence of the single-particle potential at high enough densities as compared to that adopting the pure two-body force. The effects of three-body force and ground state correlations on the nucleon effective mass are also discussed.Comment: 14 pages, 5 figure

Relativistic Approach to Superfluidity in Nuclear Matter

Pairing correlations in symmetric nuclear matter are studied within a relativistic mean-field approximation based on a field theory of nucleons coupled to neutral ($\sigma$ and $\omega$) and to charged ($\varrho$) mesons. The Hartree-Fock and the pairing fields are calculated in a self-consistent way. The energy gap is the result of a strong cancellation between the scalar and vector components of the pairing field. We find that the pair amplitude vanishes beyond a certain value of momentum of the paired nucleons. This fact determines an effective cutoff in the gap equation. The value of this cutoff gives an energy gap in agreement with the estimates of non relativistic calculations.Comment: 21 pages, REVTEX, 8 ps-figures, to appear in Phys.Rev.C. e-mail: [email protected]

Is depression a real risk factor for acute myocardial infarction mortality? A retrospective cohort study

Background: Depression has been associated with a higher risk of cardiovascular events and a higher mortality in patients with one or more comorbidities. This study investigated whether continuative use of antidepressants (ADs), considered as a proxy of a state of depression, prior to acute myocardial infarction (AMI) is associated with a higher mortality afterwards. The outcome to assess was mortality by AD use. Methods: A retrospective cohort study was conducted in the Veneto Region on hospital discharge records with a primary diagnosis of AMI in 2002-2015. Subsequent deaths were ascertained from mortality records. Drug purchases were used to identify AD users. A descriptive analysis was conducted on patients' demographics and clinical data. Survival after discharge was assessed with a Kaplan-Meier survival analysis and Cox's multiple regression model. Results: Among 3985 hospital discharge records considered, 349 (8.8%) patients were classified as AD users'. The mean AMI-related hospitalization rate was 164.8/100,000 population/year, and declined significantly from 204.9 in 2002 to 130.0 in 2015, but only for AD users (-40.4%). The mean overall follow-up was 4.64.1years. Overall, 523 patients (13.1%) died within 30days of their AMI. The remainder survived a mean 5.3 +/- 4.0years. After adjusting for potential confounders, use of antidepressants was independently associated with mortality (adj OR=1.75, 95% CI: 1.40-2.19). Conclusions: Our findings show that AD users hospitalized for AMI have a worse prognosis in terms of mortality. The use of routinely-available records can prove an efficient way to monitor trends in the state of health of specific subpopulations, enabling the early identification of AMI survivors with a history of antidepressant use

Spectral function at high missing energies and momenta

The nuclear spectral function at high missing energies and momenta has been determined from a self-consistent calculation of the Green's function in nuclear matter using realistic nucleon-nucleon interactions. The results are compared with recent experimental data derived from ($e,e'p$) reactions on $^{12}C$. A rather good agreement is obtained if the Green's functions are calculated in a non-perturbative way.Comment: 10 pages, 3 figure

Chaotic Scattering in Heavy--Ion Reactions

We discuss the relevance of chaotic scattering in heavy--ion reactions at energies around the Coulomb barrier. A model in two and three dimensions which takes into account rotational degrees of freedom is discussed both classically and quantum-mechanically. The typical chaotic features found in this description of heavy-ion collisions are connected with the anomalous behaviour of several experimental data.Comment: 35 pages in RevTex (version 3.0) plus 27 PostScript figures obtainable by anonymous ftp from VAXFCT.CT.INFN.IT in directory kaos. Fig. 1 upon request to the authors. To be published in the October Focus issue on chaotic scattering of CHAO

Neutrino Electromagnetic Form Factors Effect on the Neutrino Cross Section in Dense Matter

The sensitivity of the differential cross section of the interaction between neutrino-electron with dense matter to the possibly nonzero neutrino electromagnetic properties has been investigated. Here, the relativistic mean field model inspired by effective field theory has been used to describe non strange dense matter, both with and without the neutrino trapping. We have found that the cross section becomes more sensitive to the constituent distribution of the matter, once electromagnetic properties of the neutrino are taken into account. The effects of electromagnetic properties of neutrino on the cross section become more significant for the neutrino magnetic moment mu_nu > 10^{-10} mu_B and for the neutrino charge radius R > 10^{-5} MeV^{-1}.Comment: 24 pages, 10 figures, submitted to Physical Review