Breakup in nucleon-deuteron scattering with Δ-isobar excitation

Breakup in nucleon-deuteron scattering is described. The description is based on a coupled-channel two-baryon potential that allows for the virtual excitation of a nucleon to a Δ isobar. The Coulomb interaction is not included. Channel coupling gives rise to an effective three-nucleon force. The three-particle scattering equations are solved by real-axis integration using a separable expansion of the two-baryon transition matrix. Examples for spin-averaged and spin-dependent observables are calculated and compared with experimental data

Three- and Four-Body Scattering Calculations including the Coulomb Force

The method of screening and renormalization for including the Coulomb interaction in the framework of momentum-space integral equations is applied to the three- and four-body nuclear reactions. The Coulomb effect on the observables and the ability of the present nuclear potential models to describe the experimental data is discussed.Comment: Proceedings of the Critical Stability workshop, Erice, Sicily, October 2008, to be published in Few-Body System

Viscosities of the Gay-Berne nematic liquid crystal

We present molecular dynamics simulation measurements of the viscosities of the Gay-Berne phenomenological model of liquid crystals in the nematic and isotropic phases. The temperature dependence of the rotational and shear viscosities, including the nonmonotonic behavior of one shear viscosity are in good agreement with experimental data. The bulk viscosities are significantly larger than the shear viscosities, again in agreement with experiment.Comment: 11 pages, 4 Postscript figures, Revte

Typology of the antegonial notch in the human mandible

Background: Surgical treatment for serious malocclusions and fractures of the organ of mastication is a golden standard in medicine. Procedures performed on the mandible require detailed knowledge of the anatomy of the organ. Antegonial notching constitutes a serious technical challenge for surgeons. Therefore, a detailed anatomical description of this structure, which is the subject of this paper, is essential. Materials and methods: We analysed 251 human Caucasian mandibles of identified sex and took measurements of all sections describing the mandibular antegonial notch. Depending on the proportion between sections we classified the shape of the antegonial notch into three types. The surface area of the notch was calculated. We analysed the dimorphic and bilateral differences for each of the three types of notch. We used variance analysis for the assessment of statistical difference. Results: The analysis revealed that in both men and women, regardless of body side, the type 3 antegonial notch was the most frequent. Type 3 occurred with a frequency of between 38% in men on the right side and 55.9% in women on the left side of the body. Type 1 was the least frequent. Dimorphic differences in the presence of individual types of antegonial notch were statistically significant only for the left side of the body. The symmetrical type (type 2) occurred more frequently in men (by 11%) than in women. Type 3 was found more frequently in women (by 10%) than in men. Bilateral differences in men were revealed for the frequencies of types 1 and 3. On the right side type 1 was more frequent (by 8%), and on the left side type 3 was also more frequent (by 8%). The greatest surface area was found for the asymmetrical posterior type (type 1). The smallest surface area was found for the asymmetrical anterior type 3. This difference was statistically significant with respect to the surface area of types 1 and type 2 and found for both sexes for both sides of the body. However, no statistically significant differences were found between the surface areas of types 1 or 2. Conclusions: Knowledge of the preangular notch anatomy can be useful for surgeons during reconstructive and plastic procedures on the body of the mandible

Evolution of Li, Be and B in the Galaxy

In this paper we study the production of Li, Be and B nuclei by Galactic cosmic ray spallation processes. We include three kinds of processes: (i) spallation by light cosmic rays impinging on interstellar CNO nuclei (direct processes); (ii) spallation by CNO cosmic ray nuclei impinging on interstellar p and 4He (inverse processes); and (iii) alpha-alpha fusion reactions. The latter dominate the production of 6Li and 7Li. We calculate production rates for a closed-box Galactic model, verifying the quadratic dependence of the Be and B abundances for low values of Z. These are quite general results and are known to disagree with observations. We then show that the multi-zone multi-population model we used previously for other aspects of Galactic evolution produces quite good agreement with the linear trend observed at low metallicities without fine tuning. We argue that reported discrepancies between theory and observations do not represent a nucleosynthetic problem, but instead are the consequences of inaccurate treatments of Galactic evolution.Comment: 26 pages, 5 figures, LaTeX. The Astrophysical Journal, in pres

Phase Mixing of Alfvén Waves Near a 2D Magnetic Null Point

The propagation of linear Alfvén wave pulses in an inhomogeneous plasma near a 2D coronal null point is investigated. When a uniform plasma density is considered, it is seen that an initially planar Alfvén wavefront remains planar, despite the varying equilibrium Alfvén speed, and that all the wave collects at the separatrices. Thus, in the non-ideal case, these Alfvénic disturbances preferentially dissipate their energy at these locations. For a non-uniform equilibrium density, it is found that the Alfvén wavefront is significantly distorted away from the initially planar geometry, inviting the possibility of dissipation due to phase mixing. Despite this however, we conclude that for the Alfvén wave, current density accumulation and preferential heating still primarily occur at the separatrices, even when an extremely non-uniform density profile is considered

The phenology of winter rye in Poland: an analysis of long-term experimental data

The study of the phenology of crops, although quite popular, has limitations, mainly because of frequent changes to crop varieties and management practices. Here, we present data on the phenology and yield of winter rye in western Poland collected between 1957 and 2012 from a long-term field experiment. Data were examined for trends through time and compared to climatological factors using regression analysis. Both annual air temperature and precipitation increased during the study period, equivalent to 2 °C and 186 mm, respectively, over the 52-year period for which met data were available. We detected significant delays in sowing date and recently in emergence, but significant advances were apparent in full flowering date equivalent to 4 days/decade. Yield and plant density experienced a step like change in 1986; yield increasing by ca. 70 % and plant density increasing by ca. 50 %, almost coinciding with a similar change in annual mean temperature, but most likely caused by a changed seed rate and use of herbicides. Future climate change is expected to have a greater impact on this crop, but farmers may be able to adapt to these changes by modifying water regimes, using new machinery and sowing new rye varieties

Investigation of the Exclusive 3He(e,e'pp)n Reaction

Cross sections for the 3He(e,e'pp)n reaction were measured over a wide range of energy and three- momentum transfer. At a momentum transfer q=375 MeV/c, data were taken at transferred energies omega ranging from 170 to 290 MeV. At omega=220 MeV, measurements were performed at three q values (305, 375, and 445 MeV/c). The results are presented as a function of the neutron momentum in the final-state, as a function of the energy and momentum transfer, and as a function of the relative momentum of the two-proton system. The data at neutron momenta below 100 MeV/c, obtained for two values of the momentum transfer at omega=220 MeV, are well described by the results of continuum-Faddeev calculations. These calculations indicate that the cross section in this domain is dominated by direct two-proton emission induced by a one-body hadronic current. Cross section distributions determined as a function of the relative momentum of the two protons are fairly well reproduced by continuum-Faddeev calculations based on various realistic nucleon-nucleon potential models. At higher neutron momentum and at higher energy transfer, deviations between data and calculations are observed that may be due to contributions of isobar currents.Comment: 14 pages, 1 table, 17 figure

Beryllium abundances in stars hosting giant planets

We have derived beryllium abundances in a wide sample of stars hosting planets, with spectral types in the range F7V-K0V, aimed at studying in detail the effects of the presence of planets on the structure and evolution of the associated stars. Predictions from current models are compared with the derived abundances and suggestions are provided to explain the observed inconsistencies. We show that while still not clear, the results suggest that theoretical models may have to be revised for stars with Teff<5500K. On the other hand, a comparison between planet host and non-planet host stars shows no clear difference between both populations. Although preliminary, this result favors a ``primordial'' origin for the metallicity ``excess'' observed for the planetary host stars. Under this assumption, i.e. that there would be no differences between stars with and without giant planets, the light element depletion pattern of our sample of stars may also be used to further investigate and constraint Li and Be depletion mechanisms.Comment: A&A in press -- accepted on the 22/02/2002 (11 pages, 6 figures included