A Fast Gradient and Function Sampling Method for Finite Max-Functions

This paper tackles the unconstrained minimization of a class of nonsmooth and nonconvex functions that can be written as finite max-functions. A gradient and function-based sampling method is proposed which, under special circumstances, either moves superlinearly to a minimizer of the problem of interest or superlinearly improves the optimality certificate. Global and local convergence analysis are presented, as well as illustrative examples that corroborate and elucidate the obtained theoretical results

IRIS Observations of the Mg II h & k Lines During a Solar Flare

The bulk of the radiative output of a solar flare is emitted from the chromosphere, which produces enhancements in the optical and UV continuum, and in many lines, both optically thick and thin. We have, until very recently, lacked observations of two of the strongest of these lines: the Mg II h & k resonance lines. We present a detailed study of the response of these lines to a solar flare. The spatial and temporal behaviour of the integrated intensities, k/h line ratios, line of sight velocities, line widths and line asymmetries were investigated during an M class flare (SOL2014-02-13T01:40). Very intense, spatially localised energy input at the outer edge of the ribbon is observed, resulting in redshifts equivalent to velocities of ~15-26km/s, line broadenings, and a blue asymmetry in the most intense sources. The characteristic central reversal feature that is ubiquitous in quiet Sun observations is absent in flaring profiles, indicating that the source function increases with height during the flare. Despite the absence of the central reversal feature, the k/h line ratio indicates that the lines remain optically thick during the flare. Subordinate lines in the Mg II passband are observed to be in emission in flaring sources, brightening and cooling with similar timescales to the resonance lines. This work represents a first analysis of potential diagnostic information of the flaring atmosphere using these lines, and provides observations to which synthetic spectra from advanced radiative transfer codes can be compared.Comment: 12 pages, 14 figures, Accepted for publication in Astronomy and Astrophysic

The spectral content of SDO/AIA 1600 and 1700 \AA\ filters from flare and plage observations

The strong enhancement of the ultraviolet emission during solar flares is usually taken as an indication of plasma heating in the lower solar atmosphere caused by the deposition of the energy released during these events. Images taken with broadband ultraviolet filters by the {\em Transition Region and Coronal Explorer} (TRACE) and {\em Atmospheric Imaging Assembly} (AIA 1600 and 1700~\AA) have revealed the morphology and evolution of flare ribbons in great detail. However, the spectral content of these images is still largely unknown. Without the knowledge of the spectral contribution to these UV filters, the use of these rich imaging datasets is severely limited. Aiming to solve this issue, we estimate the spectral contributions of the AIA UV flare and plage images using high-resolution spectra in the range 1300 to 1900~\AA\ from the Skylab NRL SO82B spectrograph. We find that the flare excess emission in AIA 1600~\AA\ is { dominated by} the \ion{C}{4} 1550~\AA\ doublet (26\%), \ion{Si}{1} continua (20\%), with smaller contributions from many other chromospheric lines such as \ion{C}{1} 1561 and 1656~\AA\ multiplets, \ion{He}{2} 1640~\AA, \ion{Si}{2} 1526 and 1533~\AA. For the AIA 1700~\AA\ band, \ion{C}{1} 1656~\AA\ multiplet is the main contributor (38\%), followed by \ion{He}{2} 1640 (17\%), and accompanied by a multitude of other, { weaker} chromospheric lines, with minimal contribution from the continuum. Our results can be generalized to state that the AIA UV flare excess emission is of chromospheric origin, while plage emission is dominated by photospheric continuum emission in both channels.Comment: Accepted for publication in ApJ Skylab NRL SO82B data used in this work available at http://dx.doi.org/10.5525/gla.researchdata.68

Investigação sobre a capacidade de sobrevivência durante o inverno na ilha Terceira, Açores, de Istocheta aldrichi (Mesnil) (Diptera: Tachinidae) um parasitóide de Popillia japonica Newman (Coleoptera: Scarabaeidae).

A study of diapause in the parasitic fly Istocheta aldrichi (Diptera: Tachinidae) was undertaken to help investigate the possibility of its establishment in Terceira as a biological control agent of the Japanese beetle, Popillia japonica (Coleoptera: Scarabaeidae). It was concluded that pupae should be imported from the USA only when they are almost ready to emerge, and to optimise rearing conditions there to increase emergence percentages. Conditions are not ideal for its development in Terceira, as this univoltine parasitoid has a high pupal mortality both in laboratory cultures and outdoors during the overwintering period. These studies should continue until I. aldrichi has become established in the Azores

Kinetics of laccase mediator system delignification of an Eucalyptus globulus Kraft pulp

Comunicação da qual só está disponível o resumo.Laccase mediator system (LMS) was applied to one industrial Eucalyptus globulus kraft pulp with kappa numbers 15.2, using violuric acid (VA) as mediator. The objective of the present work is to quantify the influence of the reaction conditions on the delignification rate and extent, establishing the kinetic equations. The effects of oxygen pressure, laccase and mediator charges, and reaction time on delignification were evaluated. The kinetic studies were carried out in a 1.5 L jacketed reactor with temperature control and magnetic mixer. The experiments were carried out with 10 grams of pulp at very low consistency (0.6%) in order to minimize inter-fibre mass transfer resistances. The oxygen pressure was varied between 1 and 7 bar and no significant differences were observed in terms of delignification rate and extent, at a given charge of laccase and mediator. The laccase (EC 1.10.3.2) charge was ranged between 10 and 250 IU per gram of pulp and the mediator between 10 and 70 mg per gram of pulp. The presence of mediator is required because the enzyme cannot diffuse into the porous structure of the fibre wall, where lignin should be oxidised. The delignification potential of the LMS was evaluated by measuring the kappa number of the pulp, after alkaline extraction. Control tests similar to the LMS followed by alkaline extraction, but without enzyme, were carried out and the mean value of kappa number was 14.04. The decrease of the kappa number of the pulp from 15.2 to 14.04 can be interpreted as the consequence of the extraction of some fragments of lignin during the two stages. This procedure enable us to access the real effect of laccase. The hexeneuronic acid (HexA) has, particularly in hardwood pulps, an important contribution to the kappa number value. However, the experimental data have shown that LMS does not remove significantly the HexA, which is in good agreement with the literature. So, the kappa number can be used to evaluate the potential of LMS to lignin extraction. For the levels of laccase 50 IU per gram and 40 mg of VA per gram, the delignification was reached 37%, which is a good result. The profile of kappa number with reaction time follows an exponential trend. In addition, the initial rate methodology is being used to quantify the influence of laccase and mediator concentrations on the kinetic rate. The data have shown that the delignification rate exhibits a linear dependence on the mediator concentration, for the low range tested. The effect of laccase charge seems to be lower. The experimental data are under exploitation