The asymmetric profile of the H76 alpha line emission from MWC349

MWC349 is an emission-line star found by Merrill, Humason and Burwell (1932). Braes, Habing and Schoenmaker (1972) discovered that it is a strong radio source. The radio emission originates in a massive ionized wind that is expanding with a velocity of about 50 km s(-1). Its continuum spectrum fits well a nu(0.6) power law from the cm wavelengths to the far-IR. Radio recombination line emission from the envelope of MWC349 was first detected by Altenhoff, Strittmatter and Wendker (1981). We have obtained good signal-to-noise ratio, Very Large Array observations of the H76 alpha radio recombination line from the ionized wind of MWC349. Our data reveal that the profile is markedly asymmetric, with a steep rise on the blue side. This asymmetry could be due to non-LTE effects in the formation and transfer of the line or to intrinsic asymmetries in the envelope. Our analysis suggests that most probably the peculiar profile is caused by a non-LTE enhancement of the line emission from the side of the envelope nearer to the observer. This asymmetry has the opposite sense than that observed in optical and IR recombination lines, where a different effect (absorption of the stellar continuum by the gas in the wind between the star and the observer) is known to be dominant, leading to the classic P Cygni profile. We propose that the profiles of the radio recombination lines from ionized stellar winds will have this characteristic shape, while optical and IR recombination lines are characterized by P Cygni-like profiles. Unfortunately, at present the detection of radio recombination lines from ionized stellar winds is only feasible for MWC349 and a few other objects

Effective Widths and Effective Number of Phonons of Multiphonon Giant Resonances

We discuss the origin of the difference between the harmonic value of the width of the multiphonon giant resonances and the smaller observed value. Analytical expressions are derived for both the effective width and the average cross-section. The contribution of the Brink-Axel mechanism in resolving the discrepancy is pointed out.Comment: 9 pages, 4 figure

The Semiclassical Coulomb Interaction

The semiclassical Coulomb excitation interaction is at times expressed in the Lorentz gauge in terms of the electromagnetic fields and a contribution from the scalar electric potential. We point out that the potential term can make spurious contributions to excitation cross sections, especially when the the decay of excited states is taken into account. We show that, through an appropriate gauge transformation, the excitation interaction can be expressed in terms of the electromagnetic fields alone.Comment: 12 pages. Phys. Rev. C, Rapid Communication, in pres

Jet Deflection via Cross winds: Laboratory Astrophysical Studies

We present new data from High Energy Density (HED) laboratory experiments designed to explore the interaction of a heavy hypersonic radiative jet with a cross wind. The jets are generated with the MAGPIE pulsed power machine where converging conical plasma flows are produced from a cylindrically symmetric array of inclined wires. Radiative hypersonic jets emerge from the convergence point. The cross wind is generated by ablation of a plastic foil via soft-X-rays from the plasma convergence region. Our experiments show that the jets are deflected by the action of the cross wind with the angle of deflection dependent on the proximity of the foil. Shocks within the jet beam are apparent in the data. Analysis of the data shows that the interaction of the jet and cross wind is collisional and therefore in the hydro-dynamic regime. MHD plasma code simulations of the experiments are able to recover the deflection behaviour seen in the experiments. We consider the astrophysical relevance of these experiments applying published models of jet deflection developed for AGN and YSOs. Fitting the observed jet deflections to quadratic trajectories predicted by these models allows us to recover a set of plasma parameters consistent with the data. We also present results of 3-D numerical simulations of jet deflection using a new astrophysical Adaptive Mesh Refinement code. These simulations show highly structured shocks occurring within the beam similar to what was observed in the experimentsComment: Submitted to ApJ. For a version with figures go to http://web.pas.rochester.edu/~afrank/labastro/CW/Jet-Wind-Frank.pd

The total reaction cross section of heavy-ion reactions induced by stable and unstable exotic beams: The low-energy regime

In this review paper we present a detailed account of the extraction and the calculation of the total reaction cross section of strongly bound and weakly bound, stable and unstable, exotic, nuclei. We discuss the optical model and the more general coupled channels model of direct reactions. The effect of long-range absorption due to the coupling to excited states in the target and to the breakup continuum in the projectile is also discussed. The generalized optical theorem for charged particle scattering and the resulting sum-of differences method is then discussed. The so-called "quarter-point recipe" is discussed next, and the quarter-point angle is introduced as a simple and rapid mean to obtain the total reaction cross section. The last topic discussed is the reduction of the total reaction cross section that would allow a large body of data to sit on a single universal function. Such a universal function exists in the case of the fusion data, and the aim of this last topic of the review is to extend the fusion case to the total reaction, by adding the direct reaction contribution. Also discussed is the inclusive breakup cross section and how it can be used to extract the total reaction cross section of the interacting fragment with the target. This method is also known as the Surrogate method and represents a case of hybrid reactions. The sum of the integrated inclusive breakup cross section with the complete fusion cross section supplies the total fusion cross section. The main experimental methods to determine the total reaction cross section are also discussed, with emphasis in recent techniques developed to deal with reactions induced by unstable beams.Comment: 43 pages, 27 figures, submitted to EPJA (under review

CIAT research on improving livelihoods of smallholder coffee producers in Nicaragua

The results of CIAT’s studies have provided the scientific basis for the collaborative design and implementation of a series of CRS-led projects, also providing recommendations and lessons learned from each project into the proposal and implementation of the next. In this study, we specifically evaluate the short-term impacts of a project for the improvement of smallholder coffee producers’ livelihoods carried out in Nicaragua by CRS with collaboration from CIAT between 2011 and 2014. The project, called “BRIDGES: Bridges from Scarcity to Sufficiency’’ was the latest in a chain of interventions in Nicaragua led by CRS, and to which CIAT has contributed since 2009. Based on data collected in 2014 to help design and to assign treatment and control groups for a new CRS project (Resilience to Rust), which include information on BRIDGES participants, our findings show that participation in the BRIDGES project has increased months of adequate food provision (MAHFP) for project beneficiaries by 0.3 months, by increasing economic access to food via increased production. Participation in BRIDGES appears associated with an increase in bean yields, of about 230 kg per hectare, and in an increase of almost one income source, however these results are sensitive to different model specifications. Finally, participations in BRIDGES appears associated with a 6% reduction in household dependency from coffee income

Probing the Structure of Halo Nuclei

Our understanding of halo nuclei has so far relied on high-energy scattering and reactions, but a number of uncertainties remain. I discuss in general terms the new range of observables which will be measured by experiments around the Coulomb barrier, and how some details of the reaction mechanisms still need to be clarified.Comment: Proceedings of FUSION97 conference (March 1997), South Durras, Australia. Submitted to J. Physics G: special issue `Heavy ion collisions at near barrier energies'. No figures; uses IOPConf.sty (included

Experiments on the induced breeding of milkfish, Chanos chanos (Forsskal) in 1978

Results indicated that a female having eggs with an average diameter of < 0.7 mm did not respond well to the hormone injections

The effect of a stellar magnetic variation on the jet velocity

Stellar jets are normally constituted by chains of knots with some periodicity in their spatial distribution, corresponding to a variability of order of several years in the ejection from the protostar/disk system. A widely accepted theory for the presence of knots is related to the generation of internal working surfaces due to variations in the jet ejection velocity. In this paper we study the effect of variations in the inner disk-wind radius on the jet ejection velocity. We show that a small variation in the inner disk-wind radius produce a variation in the jet velocity large enough to generate the observed knots. We also show that the variation in the inner radius may be related to a variation of the stellar magnetic field.Comment: 5 pages, 3 figures, accepted for publication in Ap

Observations on the artificial fertilization of eggs and larval rearing of the grey mullet, Mugil cephalus L.

The results are presented of attempts to artificially fertilize Mugil cephalus eggs in the Philippines. Embryonic development is outlined and rearing of the larvae described. Mass mortality occurred during week 3 of rearing