Space and time variations of KI 7699 solar line profile     

T. Roca-Cortes  H. Wöhl  M. Vazquez 《Solar physics》1983,88(1-2):1-8

The temporal and spatial behaviour of the Ki7699 line profile is investigated. In particular we have measured the asymmetries of the line profile at several residual intensities using the bisector method. We find, in the bisector of the mean line profile, similar shapes as those obtained before for different positions on the solar disk. However the strong variations of the bisector found with time and geometry of input aperture, warns us against the use of the mean or integrated profiles (either in time or space). Moreover, we find an anticorrelation between the asymmetry in the line profile at different residual intensities and the shift, found as the distance to a terrestrial line, for any position observed on the solar disk. No limb effect for this line is found, within errors.  相似文献   

The Cerro Bitiche Andesitic Field: petrological diversity and implications for magmatic evolution of mafic volcanic centers from the northern Puna     

Guadalupe Maro  Pablo J. Caffe 《Bulletin of Volcanology》2016,78(7):51

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A morphological study of the light-bridges in sunspots     

M. Vazquez 《Solar physics》1973,31(2):377-387

This study is based on photographs taken during the period March 1971 to June 1972. Various morphological features observed are described and their possible role in sunspot evolution discussed. It is pointed out that a light-bridge looks like the re-establishment of photospheric-like conditions.  相似文献   

Discovery of 10 pulsars in an Arecibo drift-scan survey     

D. R. Lorimer  K. M. Xilouris  A. S. Fruchter  I. H. Stairs  F. Camilo  A. M. Vazquez  J. A. Eder  M. A. McLaughlin  M. S. E. Roberts  J. W. T. Hessels  S. M. Ransom 《Monthly notices of the Royal Astronomical Society》2005,359(4):1524-1530

We present the results of a 430-MHz survey for pulsars conducted during the upgrade to the 305-m Arecibo radio telescope. Our survey covered a total of 1147 deg² of sky using a drift-scan technique. We detected 33 pulsars, 10 of which were not known prior to the survey observations. The highlight of the new discoveries is PSR J0407+1607, which has a spin period of 25.7 ms, a characteristic age of 1.5 Gyr and is in a 1.8-yr orbit about a low-mass  (>0.2 M_⊙)  companion. The long orbital period and small eccentricity  ( e = 0.0009)  make the binary system an important new addition to the ensemble of binary pulsars suitable to test for violations of the strong equivalence principle. We also report on our initially unsuccessful attempts to detect optically the companion to J0407+1607, which imply that its absolute visual magnitude is >12.1. If, as expected on evolutionary grounds, the companion is an He white dwarf, our non-detection implies a cooling age of least 1 Gyr.  相似文献   

The effect of dried and cracked sediment on the availability of phosphorus in a coastal lagoon     

Virgilio Arenas  Guadalupe de la Lanza 《Estuaries and Coasts》1981,4(3):206-212

Caimanero Lagoon (Sinaloa, México) is subjected to alternate periods of low water and flooding. In the first case, more than 70% of the lagoon is dry, cracked and colonized by halophytes to a variable proportion. During the dry season, mineralization of organic matter and reavailability of phosphorus takes place to a great extent. So far, the effect of dried and cracked sediment on the reincorporation of phosphorus to the coastal lagoon ecosystem has not been evaluated. This work is the result of experiments which emulate natural conditions present during the dry season and the beginning of the flood season under the influence of tidal flux. The availability of phosphorus (orthophosphates and soluble phosphates) was significantly increased in the dry and cracked material; this phosphorus is derived from the mineralization of organic matter present in the sediment. The amount of soluble organic matter also increased during the dry season. The sedimentary drying and cracking process contributes significantly to estuarine productivity.  相似文献   

Wind wave climate change: Impacts on the littoral processes at the Northern Buenos Aires Province Coast, Argentina     

Walter C. Dragani  Paula B. Martin  Guadalupe Alonso  Jorge O. Codignotto  Bárbara E. Prario  Guido Bacino 《Climatic change》2013,121(4):649-660

Several works reported wind-wave climate changes at Buenos Aires Province continental shelf. The aim of this work is to investigate the impact of these changes in the coastal processes of the region. This study is carried out by means of visual wave parameters gathered at the surf zone of Pinamar and by a conveniently implemented and validated numerical wave model (SWAN). Numerical results corresponding to a grid point located 30 km off Pinamar show a significant increase of wave heights from the S and SSE directions and in the frequency of occurrence of waves coming from the S, SSE and E. It is shown that these slight offshore appreciated trends would not have significant effects on the breaker heights observed at the surf zone at Pinamar. On the contrary, the slight positive trend observed offshore in the frequency of occurrence could be affecting the incidence of waves onshore, producing an increase in the number of cases of normal incidence at the surf zone and, consequently, a significant decrease in the alongshore wave energy flux assessed at Pinamar. This reduction in the alongshore wave energy flux could be responsible for some coastal changes detected in the region as, for instance, the remarkable shortening of Punta Rasa spit located 70 km northward Pinamar.  相似文献   

Susceptibility to gravitational processes due to land cover change in the Río Chiquito-Barranca del Muerto subbasin(Pico De Orizaba Volcano,México)     

Rocío Marisol Alanís-Anaya  Gabriel Legorreta-Paulín  Jean François Mas  Guadalupe Rebeca Granados-Ramírez 《山地科学学报》2017,14(12):2511-2526

Land cover change can lead to slope instability by accelerating erosive processes associated with agriculture, forestry, and infrastructure. The Rio Chiquito-Barranca del Muerto subbasin has experienced an increase in land cover change due to government programs and the establishment of agricultural and urban areas. The aim of this study was to provide a model to map the susceptibility to gravitational processes along sites where anthropogenic land cover change has occurred. The method was based on the stratification of the subbasin according to landforms and cartographic variables. These variables were used in a multi-criteria assessment to assign weights according to their contribution to the onset of new gravitational processes. Those weights were used to create a susceptibility map based on a weighted linear sum. The accuracy of the resulting map was validated in an error matrix with a random stratified design based on susceptibility classes per landform. The results produced a map of areas with susceptibility to gravitational processes due to land cover change; this susceptibility is very high in the undifferentiated pyroclastic slope and limestone mountain, where it derives not only from anthropogenic effects on natural vegetation cover, but also from steep slopes, weathered materials, low apparent density, high erosivity, and previous gravitational processes. The results support other studies that concluded that loss of vegetation is a triggering factor in the formation of gravitational processes, but also show that excessive reforestation can increase gravitational processes.  相似文献