Nuclear pairing and Coriolis effects in proton emitters

We introduce a Hartree-Fock-Bogoliubov mean-field approach to treat the problem of proton emission from a deformed nucleus. By substituting a rigid rotor in a particle-rotor-model with a mean-field we obtain a better description of experimental data in $^{141}$Ho. The approach also elucidates the softening of kinematic coupling between particle and collective rotation, the Coriolis attenuation problem.Comment: 2 pages, 1 figur

Measuring the effective phonon density of states of a quantum dot

We employ detuning-dependent decay-rate measurements of a quantum dot in a photonic-crystal cavity to study the influence of phonon dephasing in a solid-state quantum-electrodynamics experiment. The experimental data agree with a microscopic non-Markovian model accounting for dephasing from longitudinal acoustic phonons, and identifies the reason for the hitherto unexplained difference between non-resonant cavity feeding in different nanocavities. From the comparison between experiment and theory we extract the effective phonon density of states experienced by the quantum dot. This quantity determines all phonon dephasing properties of the system and is found to be described well by a theory of bulk phonons.Comment: 5 pages, 3 figures, submitte

A comparison of condition factor and gona dosomatic index of sardine Sardinops sagax stocks in the northern and southern Benguela upwelling ecosystems, 1984–1999

Time-series of condition factor (CF) and gonadosomatic index (GSI) were generated using general linear models (GLM) for sardine Sardinops sagax stocks in the northern and southern Benguela ecosystems over the period 1984–1999. During this period the biomass of sardine in the northern Benguela remained at relatively low levels of African Journal of Marine Science 2001, 23: 123–13

Changes in abundance of the northern Benguela sardine stock during the decade 1990 &#150 2000, with comments on the relative importance of fishing and the environment

The northern Benguela stock of sardine Sardinops sagax used to be considered one of the major clupeoid stocks of the world; it supported an average annual catch of >700 000 tons throughout the 1960s. The stock has been in a depressed state for more than two decades, as demonstrated by annual catches that averaged around 50 000 tons between 1978 and 1989 and only slightly more in the 1990s. It has experienced fluctuations in abundance of several orders of magnitude during the most recent decade. Population size increased until 1992, when the acoustic estimate of biomass was about 750 000 tons. Catches increased accordingly, averaging 100 000 tons between 1992 and 1995, but from 1992 to 1996 the stock was in decline and the lowest annual catch in the history of the fishery was taken in 1996. Although there was a small increase during the last three years of the decade, the stock remains seriously depleted. Survey-based recruitment indices suggest that the changes in the 1990s were initiated by fluctuations in recruitment, but the decline was almost certainly exacerbated by continued fishing. Poor recruitment and decreasing catch rates between 1993 and 1996 in a number of other key resources suggest that system-wide environmental changes were an important factor in the decline of the sardine stock at that time. Anomalous oceanographic conditions, such as extensive hypoxic shelf waters in 1993/94 and a Benguela Niño in 1995, support this conclusion.Keywords: environmental effects, fishing effects, northern Benguela, recruitment, sardineAfrican Journal of Marine Science 2001, 23: 67–8

The Best Brown Dwarf Yet?: A Companion to the Hyades Eclipsing Binary V471 Tau

We have carried out an analysis of about 160 eclipse timings spanning over 30 years of the Hyades eclipsing binary V471 Tauri that shows a long-term quasi-sinusoidal modulation of its observed eclipse arrival times. The O-Cs have been analyzed for the ``light-time'' effect that arises from the gravitational influence of a tertiary companion. The presence of a third body causes the relative distance of the eclipsing pair to the Earth to change as it orbits the barycenter of the triple system. The result of the analysis of the eclipse times yields a light-time semi-amplitude of 137.2+/-12.0 s, an orbital period of P_3 = 30.5+/-1.6 yr and an eccentricity of e_3 = 0.31+/-0.04. The mass of the tertiary component is M_3 sin i_3 = 0.0393+/-0.0038 Mo when a total mass of 1.61+/-0.06 Mo for V471 Tau is adopted. For orbital inclinations i_3 > 35 deg, the mass of the third body would be below the stable hydrogen burning limit of M = 0.07 Mo and it thus would be a brown dwarf. In the next several years (near maximum elongation), it should be feasible to obtain IR images and spectra of V471 Tau C that, when combined with the known mass, age, distance, and [Fe/H], will serve as a benchmark for understanding the physical properties and evolution of brown dwarfs.Comment: 9 pages, 3 figures, accepted for publication in ApJ Letter

Action minimizing fronts in general FPU-type chains

We study atomic chains with nonlinear nearest neighbour interactions and prove the existence of fronts (heteroclinic travelling waves with constant asymptotic states). Generalizing recent results of Herrmann and Rademacher we allow for non-convex interaction potentials and find fronts with non-monotone profile. These fronts minimize an action integral and can only exists if the asymptotic states fulfil the macroscopic constraints and if the interaction potential satisfies a geometric graph condition. Finally, we illustrate our findings by numerical simulations.Comment: 19 pages, several figure

Induced radioactivity in AB-BNCT: an analysis of the different facilities worldwide

The global effort to establish Accelerator-Based Boron Neutron Capture Therapy (AB-BNCT) facilities involves various accelerator technologies and neutron-producing targets, each characterized by different properties of the primary beam and neutron spectra they generate. With an emphasis on long-term sustainability, it is essential to minimize the production of residual radioactivity to the lowest possible level, particularly given their intended use in a hospital environment. This paper aims to quantitatively assess the residual radioactivity in these facilities, taking into account both primary and secondary activation. Primary activation primarily arises from the interaction of the proton or deuteron beam and the neutron-producing target. Secondary activation results from neutron-induced reactions on the elements exposed to the neutron flux, with the Beam Shaping Assembly (BSA) being the most exposed one. To assess activation, we evaluated a representative group of target-BSA configurations. Primary activation was calculated based on cross-sectional data and the corresponding target materials. Neutron activation was assessed using Monte Carlo simulations with the MCNP 6.1 code. Regarding target activation, our findings indicate that 9Be targets working with protons of less than 10 MeV represent the cleanest option, while 7Li targets working with protons lead to the highest activation levels. As for BSA activation, the neutron energy is a crucial factor. In the case of standard BSA materials, higher neutron energy results in an increased number of potential reactions that produce radioactive products. Additionally, our findings suggest that radioactivity induced by impurities and minor components in alloyed materials cannot be disregarded and must be taken into account in radioactivity calculations. In summary, this research provides a comprehensive analysis of activation of the commonly used targets and BSA materials, aimed at contributing to the optimization of AB-BNCT facilities from a radiological perspective

Quality Difference in Craniofacial Pain of Cardiac vs. Dental Origin

Craniofacial pain, whether odontogenic or caused by cardiac ischemia, is commonly referred to the same locations, posing a diagnostic challenge. We hypothesized that the validity of pain characteristics would be high in assessment of differential diagnosis. Pain quality, intensity, and gender characteristics were assessed for referred craniofacial pain from dental (n = 359) vs. cardiac (n = 115) origin. The pain descriptors “pressure” and “burning” were statistically associated with pain from cardiac origin, while “throbbing” and “aching” indicated an odontogenic cause. No gender differences were found. These data should now be added to those craniofacial pain characteristics already known to point to acute cardiac disease rather than dental pathology, i.e., pain provocation/aggravation by physical activity, pain relief at rest, and bilateralism. To initiate prompt and appropriate treatment, dental and medical clinicians as well as the public should be alert to those clinical characteristics of craniofacial pain of cardiac origin