Why is the nuclear symmetry energy so uncertain at supra-saturation densities?

Within the interacting Fermi gas model for isospin asymmetric nuclear matter, effects of the in-medium three-body interaction and the two-body short-range tensor force due to the $\rho$ meson exchange as well as the short-range nucleon correlation on the high-density behavior of the nuclear symmetry energy are demonstrated respectively in a transparent way. Possible physics origins of the extremely uncertain nuclear symmetry energy at supra-saturation densities are discussed.Comment: Added discussions and revised format. Version to appear in Phys. Rev. C (2010

Solution of the Bohr hamiltonian for soft triaxial nuclei

The Bohr-Mottelson model is solved for a generic soft triaxial nucleus, separating the Bohr hamiltonian exactly and using a number of different model-potentials: a displaced harmonic oscillator in $\gamma$, which is solved with an approximated algebraic technique, and Coulomb/Kratzer, harmonic/Davidson and infinite square well potentials in $\beta$, which are solved exactly. In each case we derive analytic expressions for the eigenenergies which are then used to calculate energy spectra. Here we study the chain of osmium isotopes and we compare our results with experimental information and previous calculations.Comment: 13 pages, 9 figure

Benzo-pyrones for reducing and controlling lymphoedema of the limbs.

Background Lymphoedema is the accumulation of excess fluid in the body caused by obstruction of the lymphatic drainage mechanisms. Treatment with Benzo-pyrones is thought to reduce fluid forming in the subcutaneous tissues and reduce pain and discomfort of the affected area. Objectives To assess the effectiveness of benzo-pyrones compared to placebo in the management of lymphoedema. Search strategy We searched the Cochrane Breast Cancer Group register (September 2003), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 4,2003), MEDLINE, EMBASE, CINAHL, UnCover, PASCAL, SIGLE, reference lists produced by The British Lymphology Society, the National Research Register (NRR) and The International Society of Lymphology congress proceedings. Selection criteria Randomised controlled trials comparing Benzo-pyrones with placebo. Data collection and analysis Trials were selected for eligibility and tested for quality by two blinded reviewers who independently extracted data. Meta-analysis was not performed due to the poor quality of the trials. Main results Fifteen trials were included. Three oxerutin trials tested the same dose over 6 months against placebo and included a total of 127 participants (data were available for 81). There were insufficient data from these to calculate the per cent reduction or increase in baseline excess limb volume. One trial testing Cyclo 3 Fort (approved name) was found (57 participants) but insufficient data was provided to allow a proper analysis of its findings. A single trial of Daflon (approved name) was found (104 participants) but this also provided insufficient information to reach a conclusion about the effectiveness of the drug. Three trials of coumarin combined with troxerutin were found which tested two different doses of the drug against each other with no placebo, however participant numbers and baseline data were not provided. Eight trials of coumarin were identified. Two of these reported the same trial and the other potentially also referred to the same trial but this could not be confirmed. A further two papers also appeared to refer to the same trial but again this was unconfirmed. Five studies added anti-filarial drugs to the interventions tested. Participant data could not be extracted and the reporting of outcome measures in most was unclear. Loprinzi's 1999 trial was reported in more detail but its conclusions were very much at odds with other findings. Authors' conclusions It is not possible to draw conclusions about the effectiveness of Benzopyrones in the management of lymphoedema from the current available trials

A supersymmetric model of gamma ray bursts

We propose a model for gamma ray bursts in which a star subject to a high level of fermion degeneracy undergoes a phase transition to a supersymmetric state. The burst is initiated by the transition of fermion pairs to sfermion pairs which, uninhibited by the Pauli exclusion principle, can drop to the ground state of minimum momentum through photon emission. The jet structure is attributed to the Bose statistics of sfermions whereby subsequent sfermion pairs are preferentially emitted into the same state (sfermion amplification by stimulated emission). Bremsstrahlung gamma rays tend to preserve the directional information of the sfermion momenta and are themselves enhanced by stimulated emission.Comment: published versio

Symmetry and Surface Symmetry Energies in Finite Nuclei

A study of properties of the symmetry energy of nuclei is presented based on density functional theory. Calculations for finite nuclei are given so that the study includes isospin dependent surface symmetry considerations as well as isospin independent surface effects. Calculations are done at both zero and non-zero temperature. It is shown that the surface symmetry energy term is the most sensitive to the temperature while the bulk energy term is the least sensitive. It is also shown that the temperature dependence terms are insensitive to the force used and even more insensitive to the existence of neutron skin. Results for a symmetry energy with both volume and surface terms are compared with a symmetry energy with only volume terms along the line of $\beta$ stability. Differences of several MeV are shown over a good fraction of the total mass range in $A$. Also given are calculations for the bulk, surface and Coulomb terms.Comment: 11 pages, 2 figures, Added a new tabl

Securing address registration in location/ID split protocol using ID-based cryptography

The Locator/ID Separation Protocol (LISP) is a routing architecture that provides new semantics for IP addressing. In order to simplify routing operations and improve scalability in future Internet, the LISP separates the device identity from its location using two different numbering spaces. The LISP also, introduces a mapping system to match the two spaces. In the initial stage, each LISP-capable router needs to register with a Map Server, this is known as the Registration stage. However, this stage is vulnerable to masquerading and content poisoning attacks. Therefore, a new security method for protecting the LISP Registration stage is presented in this paper. The proposed method uses the ID-Based Cryptography (IBC) which allows the mapping system to authenticate the source of the data. The proposal has been verified using formal methods approach based on the well-developed Casper/FDR tool

Electron scattering in isotonic chains as a probe of the proton shell structure of unstable nuclei

Electron scattering on unstable nuclei is planned in future facilities of the GSI and RIKEN upgrades. Motivated by this fact, we study theoretical predictions for elastic electron scattering in the N=82, N=50, and N=14 isotonic chains from very proton-deficient to very proton-rich isotones. We compute the scattering observables by performing Dirac partial-wave calculations. The charge density of the nucleus is obtained with a covariant nuclear mean-field model that accounts for the low-energy electromagnetic structure of the nucleon. For the discussion of the dependence of scattering observables at low-momentum transfer on the gross properties of the charge density, we fit Helm model distributions to the self-consistent mean-field densities. We find that the changes shown by the electric charge form factor along each isotonic chain are strongly correlated with the underlying proton shell structure of the isotones. We conclude that elastic electron scattering experiments in isotones can provide valuable information about the filling order and occupation of the single-particle levels of protons.Comment: 13 pages; 19 figure

Feshbach Resonances and Limiting Thermodynamics of Strongly Correlated Nucleons

A finite temperature model of strongly correlated nucleons with underlying isospin symmetries is developed. The model can be used to study the role of bound states and Feshbach resonances on the thermal properties of a spin 1/2, isospin 1/2 system of protons and neutrons by varying the proton fraction. An analysis of features associated with a universal thermodynamic limit or unitary limit is given. In the limit of very large scattering length, the effective range to quantum thermal wavelength appears as a limiting scale in an interaction energy and equation of state.Comment: 8 pages, 4 figure

Brueckner-Hartree-Fock study of circular quantum dots

We calculate ground state energies in the Brueckner-Hartree-Fock theory for $N$ electrons (with $N\le 20$) confined to a circular quantum dot and in presence of a static magnetic field. Comparison with the predictions of Hartree-Fock, local-spin-density and exact configuration-interaction theories is made. We find that the correlations taken into account in Brueckner-Hartree-Fock calculations give an important contribution to the ground state energies, specially in strongly confined dots. In this high-density range, corresponding in practice to self-assembled quantum dots, the results of Brueckner-Hartree-Fock calculations are close to the exact values and better than those obtained in the local-spin-density approximation.Comment: Regular articl