Helium line formation and abundance during a C-class flare

During a coordinated campaign which took place in May 2001, a C-class flare was observed both with SOHO instruments and with the Dunn Solar Telescope of the National Solar Observatory at Sacramento Peak. In two previous papers we have described the observations and discussed some dynamical aspects of the earlier phases of the flare, as well as the helium line formation in the active region prior to the event. Here we extend the analysis of the helium line formation to the later phases of the flare in two different locations of the flaring area. We have devised a new technique, exploiting all available information from various SOHO instruments, to determine the spectral distribution of the photoionizing EUV radiation produced by the corona overlying the two target regions. In order to find semiempirical models matching all of our observables, we analyzed the effect on the calculated helium spectrum both of A(He) (the He abundance) and of the uncertainties in the incident EUV radiation (level and spectral distribution). We found that the abundance has in most cases (but not in all) a larger effect than the coronal back-radiation. The result of our analysis is that, considering the error of the measured lines, and adopting our best estimate for the coronal EUV illumination, the value A(He)=0.075 +/- 0.010 in the chromosphere (for T>6300 K) and transition region yields reasonably good matches for all the observed lines. This value is marginally consistent with the most commonly accepted photospheric value: A(He)=0.085.Comment: 34 pages + 13 figures; to be published in Ap

Helium Line Formation and Abundance in a Solar Active Region

An observing campaign (SOHO JOP 139), coordinated between ground-based and Solar and Heliospheric Observatory (SOHO) instruments, has been planned to obtain simultaneous spectroheliograms of the same active region in several spectral lines. The chromospheric lines Ca ii K, H , and Na i D, as well as He i 10830, 5876, 584, and He ii 304 8 lines have been observed. The EUV radiation in the range k < 500 8 and in the range 260 < k < 340 8 has also been measured at the same time. These simultaneous observations allow us to build semiempirical models of the chromosphere and low transition region of an active region, taking into account the estimated total number of photoionizing photons impinging on the target active region and their spectral distribution. We obtained a model that matches very well all the observed line profiles, using a standard value for the He abundance (½He ¼ 0:1) and a modified distribution of microturbulence. For this model we study the influence of the coronal radiation on the computed helium lines. We find that, even in an active region, the incident coronal radiation has a limited effect on the UV He lines, while it is of fundamental importance for the D3 and 10830 8 lines. Finally, we build two more models, assuming values of He abundance ½He ¼ 0:07 and 1.5, only in the region where temperatures are >1 ; 104 K. This region, between the chromosphere and transition region, has been indicated as a good candidate for processes that might be responsible for strong variations of [He]. The set of our observables can still be well reproduced in both cases, changing the atmospheric structure mainly in the low transition region. This implies that, to choose between different values of [He], it is necessary to constrain the transition region with different observables, independent of the He lines.Fil: Mauas, Pablo Jacobo David. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Andretta, V.. Osservatorio Astronomico di Capodimonte; ItaliaFil: Falchi, A.. Osservatorio Astrofisico di Arcetri; ItaliaFil: Falciani, R.. Universita Degli Studi Di Firenze; ItaliaFil: Teriaca, L.. Max-Planck-Institut fur Sonnensystemforschung; AlemaniaFil: Cauzzi, G.. Osservatorio Astrofisico di Arcetri; Itali

RHESSI images and spectra of two small flares

We studied the evolution of two small flares (GOES class C2 and C1) that developed in the same active region with different morphological characteristics: one is extended and the other is compact. We analyzed the accuracy and the consistency of different algorithms implemented in RHESSI software to reconstruct the image of the emitting sources, for energies between 3 and 12 keV. We found that all tested algorithms give consistent results for the peak position whil the other parameters can differ at most by a factor 2. Pixon and Forward-fit generally converge to similar results but Pixon is more reliable for reconstructing a complex source. We investigated the spectral characteristics of the two flares during their evolution in the 3--25 keV energy band. We found that a single thermal model of the photon spectrum is inadequate to fit the observations and we needed to add either a non-thermal model or a hot thermal one.The non-thermal and the double thermal fits are comparable. If we assume a non-thermal model, the non-thermal energy is always higher than the thermal one.Only during the very final decay phase a single thermal model fits fairly well the observed spectrum.Comment: 26 pages, 11 figures, accepted by Solar Physic

New lines of evidence in the study of the pre-hispanic occupation of the archaeological area Los Colorados

Se presentan los resultados preliminares de la primera prospección realizada en la localidad arqueológica Los Colorados. Su objetivo fue integrar la información ya conocida sobre los bloques y paredes con arte rupestre con nuevas líneas de evidencia. Sobre la base de las concentraciones de materiales arqueológicos y otros rasgos asociados con ellas se aislaron seis polígonos en los que se observó la tendencia a utilizar espacios reparados al pie de los afloramientos para la ubicación de los asentamientos, situados cercanos a los bloques con arte rupestre, aunque no inmediatamente asociados a estos. Estos primeros resultados permiten plantear la hipótesis de que la localidad Los Colorados pudo haber funcionado como un espacio compartido estacionalmente por diferentes grupos, posiblemente destinado a actividades estacionales como la obtención de ciertos recursos silvestres. Los motivos de arte rupestre registrados en esta localidad reflejan una parte del repertorio identificado a nivel regional, lo que le daría sustento a esta idea.In this article we present the preliminary results of the first survey evidence in the archaeological area Los Colorados. The article’s objective is to integrate previous information on rock art with new lines of evidence. Based on artifact concentrations and other features, six polygons with occupation evidence were demarcated. These areas are protected by rock outcrops and near, but not immediately adjacent, to boulders with rock art. Analysis of the material evidence allows us to hypothesize that Los Colorados was a space shared by different groups and used seasonally to obtain resources. The rock art representations represent part of the iconographic diversity known from the region, supporting this idea.Fil: Guraieb, A. Gabriela. Instituto Nacional de Antropología y Pensamiento Latinoamericano (Argentina).Fil: Falchi, María Pía. Instituto Nacional de Antropología y Pensamiento Latinoamericano (Argentina).Fil: Rambla, Marcos J.. Instituto Nacional de Antropología y Pensamiento Latinoamericano (Argentina).Fil: Carro, E. Diana. Instituto Nacional de Antropología y Pensamiento Latinoamericano (Argentina).Fil: Pérez Massone, Patricia. Instituto Nacional de Antropología y Pensamiento Latinoamericano (Argentina)

Dynamics of the chromospheric flares

In this paper, I describe how chromospheric observations of a flare are used to locate the footpoints of the flaring loops and to analyse the response to the energy release during a flare. In particular, a red asymmetry in chromospheric lines is often observed during the impulsive phase of flares and is explained as due to Doppler-shifted emission of downward-moving chromospheric plasma. Using flare dynamic models that simulate in detail the physical conditions within the chromosphere, observables such as the response time, the duration and the peak value of the downflow velocity can yield information on the flare energetics. Moreover, this downward velocity is a chromospheric signature present in major events as well as in micro-flares, and seems to be a very distinctive characteristics of the flare process, more than the increasing intensity itself

Eficiência alimentar entre novilhos Nelore confinados em diferentes instalações.

O objetivo do trabalho é avaliar o efeito de diferentes instalações na eficiência alimentar de bovinos de corte confinados

Consumo alimentar residual como índice de eficiência alimentar e suas implicações na qualidade de carne de novilhos Nelore.

A eficiência alimentar caracteriza-se como uma medida bruta obtida através da razão entre o consumo e o ganho de peso. Por ser correlacionada com peso vivo, pode apresentar limitações de utilização como parâmetro de identificação de animais eficientes por promover aumento no tamanho adulto do rebanho. Um índice alternativo de eficiência que não levaria este aumento é o Consumo Alimentar Residual (CAR). Porém, há indícios que este índice esteja associado a mudanças na composição corporal, onde os animais mais eficientes tendem a apresentar carcaças com menor espessura de gordura de acabamento e intramuscular. Este ensaio é parte do projeto ?Estratégias genéticas para melhoria da eficiência de produção e qualidade de carne bovina no Brasil? (Sistema Embrapa de Gestão - Macroprograma 1), no qual em três anos serão avaliados geneticamente 800 novilhos, filhos de 30 touros selecionados do sumário Nacional de Touros da raça Nelore. O objetivo desta proposta será avaliar, em dois anos, as relações entre CAR, características de carcaça e qualidade de carne de 300 novilhos Nelore. Em cada ano serão confinados 150 novilhos castrados, com 18 meses de idade. A dieta irá conter 14,7% de proteína bruta e 74,1% de nutrientes digestíveis totais. Serão avaliados consumo, ganho de peso, CAR, características de carcaça, qualidade de carne e as respectivas correlações fenotípicas. Todas as mensurações de desempenho animal e de qualidade de carne serão avaliadas mediante análise de variância. As médias obtidas nas classes de CAR (alto, médio ou baixo) serão comparadas pelo teste de Tukey a 5% de probabilidade. Os coeficientes de correlação entre as variáveis serão obtidos através do procedimento CORR do SAS (2002). Espera-se que o CAR possa ser utilizado como ferramenta para permitir a seleção de animais eficientes sem comprometer a qualidade da carne

Sister Mary Joseph's Nodule at a University Teaching Hospital in Northwestern Tanzania: A Retrospective Review of 34 cases.

Sister Mary Joseph's nodule is a metastatic tumor deposit in the umbilicus and often represents advanced intra-abdominal malignancy with dismal prognosis. There is a paucity of published data on this subject in our setting. This study was conducted to describe the clinicopathological presentation and treatment outcome of this condition in our environment and highlight challenges associated with the care of these patients, and to proffer solutions for improved outcome. This was a retrospective study of histologically confirmed cases of Sister Mary Joseph's nodule seen at Bugando Medical Centre between March 2003 and February 2013. Data collected were analyzed using descriptive statistics. A total of 34 patients were enrolled in the study. Males outnumbered females by a ratio of 1.4:1. The vast majority of patients (70.6%) presented with large umbilical nodule > 2 cm in size. The stomach (41.1%) was the most common location of the primary tumor. Adenocarcinoma (88.2%) was the most frequent histopathological type. Most of the primary tumors (52.9%) were poorly differentiated. As the disease was advanced and metastatic in all patients, only palliative therapy was offered. Out of 34 patients, 11 patients died in the hospital giving a mortality rate of 32.4%. Patients were followed up for 24 months. At the end of the follow-up period, 14(60.9%) patients were lost to follow-up and the remaining 9 (39.1%) patients died. Patients survived for a median period of 28 weeks (range, 2 to 64 weeks). The nodule recurred in 6 (26.1%) patients after complete excision. Sister Mary Joseph's nodule of the umbilicus is not rare in our environment and often represents manifestation of a variety of advanced intra-abdominal malignancies. The majority of the patients present at a late stage and many with distant metastases. The patient's survival is very short leading to a poor outcome. Early detection of primary cancer at an early stage may improve the prognosis

The solar chromosphere at high resolution with IBIS. I. New insights from the Ca II 854.2 nm line

(Abridged) Aims: In this paper, we seek to establish the suitability of imaging spectroscopy performed in the Ca II 854.2 nm line as a means to investigate the solar chromosphere at high resolution. Methods: We utilize monochromatic images obtained with the Interferometric BIdimensional Spectrometer (IBIS) at multiple wavelengths within the Ca II 854.2 nm line and over several quiet areas. We analyze both the morphological properties derived from narrow-band monochromatic images and the average spectral properties of distinct solar features such as network points, internetwork areas and fibrils. Results: The spectral properties derived over quiet-Sun targets are in full agreement with earlier results obtained with fixed-slit spectrographic observations, highlighting the reliability of the spectral information obtained with IBIS. Furthermore, the very narrowband IBIS imaging reveals with much clarity the dual nature of the Ca II 854.2 nm line: its outer wings gradually sample the solar photosphere, while the core is a purely chromospheric indicator. The latter displays a wealth of fine structures including bright points, akin to the Ca II H2V and K2V grains, as well as fibrils originating from even the smallest magnetic elements. The fibrils occupy a large fraction of the observed field of view even in the quiet regions, and clearly outline atmospheric volumes with different dynamical properties, strongly dependent on the local magnetic topology. This highlights the fact that 1-D models stratified along the vertical direction can provide only a very limited representation of the actual chromospheric physics.Comment: 13 pages, 8 figures. Accepted in A&A. Revised version after referee's comments. New Fig. 1 and 7. Higher quality figures in http://www.arcetri.astro.it/~gcauzzi/papers/ibis.caii.pd