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During the declining phase of the longest solar minimum in a century, the arrival of the MESSENGER spacecraft at superior conjunction allowed the measurement of magnetohydrodynamic (MHD) waves in the solar corona with its 8 GHz radio frequency signal. MHD waves crossing the line of sight were measured via Faraday rotation fluctuations (FRFs) in the plane of polarization (PP) of MESSENGER's signal. FRFs in previous observations of the solar corona (at greater offset distances) consisted of a turbulent spectrum that decreased in power with increasing frequency and distance from the Sun. Occasionally a spectral line, a distinct peak in the power spectral density spectrum around 4 to 8 mHz, was also observed in these early data sets at offset distances of about 5 to 10 solar radii. The MESSENGER FRF data set shows a spectral line at an offset distance between 1.55 to 1.85 solar radii with a frequency of 0.6±0.2 mHz. Other possible spectral lines may be at 1.2, 1.7, and 4.5 mHz; MHD waves with these same frequencies have been observed in X-ray data traveling along closed coronal loops at lower offset distances. An initial analysis of the MESSENGER spectral line(s) shows behavior similar to turbulent spectra: decreasing power with increasing frequency and distance from the Sun. Here we detail the steps taken to process the MESSENGER change in PP data set for the MHD wave investigation. [ABSTRACT FROM AUTHOR]

Gassy sediments in the Ría de Arousa are preferentially distributed in areas of muddy seabed sediments. The close relationship between seabed sediment parameters and gas distribution is here studied in detail to establish better constraints on the presence of gas. Discriminant analysis was applied to the textural and compositional characteristics of 303 seabed sediment samples to classify gas-related and gas-free areas in the Ría de Arousa. The parameters considered in the classification were: particle size data (percentages of clay, silt, sand and gravel), the total inorganic carbon and the total organic carbon contents of the samples. The samples were initially classified in two groups according to the presence or absence of acoustic turbidity in the seismic profiles, shallower than 150 cm below seabed. Of the total known cases, 85.5% were correctly classified using these variables. Applying the Wilks’ lambda criterion, the most influential textural discriminating variables were the percentage of clay and the percentage of coarse fraction (gravel and sand) in the sediment sample. Discriminant analysis has achieved good differentiation between gas-related and gas-free sediments using near-seabed sediment information. The application of the discriminant method has enabled the estimation of the total area covered by gassy sediments in the Ría de Arousa. The area calculated based on the seismic data (30 km2) is a minimum estimate that is constrained by the limits of the existing seismic data. Based on the sediment information obtained from seabed samples, the statistical method estimates a total area of gassy sediments of 39 km2. The new gassy areas recognized are located around the gas field at the inner ría, and the gas field west of Arousa Island, which increase in area by 8.3 and 0.4 km2 respectively. [ABSTRACT FROM AUTHOR]

The Ría de Vigo is located on the NW coast of Spain, and includes gassy areas studied in several high-resolution seismic surveys between 1991 and 2001. The position of the acoustic blankings and gas seepages has been monitored vertically and spatially in the surveyed area. Also, a 253-cm-long vibrocore was recovered in a gas field in the inner part of the ría. The predominant facies of the core is dark mud with small bioclastic fragments and a very strong H2S smell. The repeated surveys of this ría show that these shallow gas fields have been active in the last decade and were active in the past (buried collapse structures). Available direct gas analyses show that methane is one of the components of the gas in the ría. Thus, bacterial degradation of organic matter in shallow sediments is considered the most likely source for the gas in the Ría de Vigo. [ABSTRACT FROM AUTHOR]

Areas with gas accumulations and gas escapes have been mapped in two rías from Galicia (Ría de Pontevedra and Arousa) and compared with already published data from the Rías de Vigo (García-Gil et al. 2002) and Muros-Noia (Magariños-Álvarez et al. accepted). Calculations indicate different areas of gas-bearing sediments for each ría. Quantitative data from acoustic plume studies and pockmark densities in the seepage areas were also obtained. In terms of the area of gas-bearing sediment and seeping activity, the Ría de Arousa is found to be the most important from a quantitative point of view. Comparison of the locations of the gas accumulations with grain size distributions of sediments reveals a spatial coincidence with finer surface sediments that are mainly muds. [ABSTRACT FROM AUTHOR]

The article offers information on the Portuguese Society of Digestive Endoscopy (SPED), which is aimed to promote the development and monitoring of training activities in the field of Digestive Endoscopy.

Presents an abstract of the article "Sediment Transport Pathways in the Ría de Vigo (NW Spain): Evidences from Benthic Foraminifera and Physical Processes ," by P. Diz, S. Costas, J. Alcántara-Carrió, I. Alejo, G. Francés and F. Villas.