Intertidal biogenic reefs built by the polychaete Boccardia proboscidea in sewage‐impacted areas of Argentina,SW Atlantic

The rocky intertidal zone around the city of Mar del Plata (SW Atlantic, 38° S–57° W) is characterized by dense mussel beds of Brachidontes rodriguezii. This intertidal community develops on natural and artificial hard substrates, including abrasion platforms in sewage‐impacted areas. A monitoring program, designed to assess the effect of sewage discharge on intertidal macrobenthic communities, has been conducted since 1997. During the spring season of 2008, a new spionid polychaete (Boccardia proboscidea) was found near the sewage outfall, forming large biogenic reefs. This is the first report of biogenic reefs being built by a non reef‐forming spionid polychaete in areas organically impacted by sewage discharges. The aim of this work was to evaluate the spatial–temporal dynamics (% cover and density of B. proboscidea) of these reefs. These biogenic reefs covered almost the entire impacted site, reaching a density of 650,000 ind·m^?2. This phenomenon is unique in that there is no other record available worldwide of any other biogenic polychaete reefs that could be sewage‐induced. The presence and stability of these biogenic reefs is discussed in relation to increased organic contamination as a structuring factor.     

Analysis of the parameterization for the wind-velocity fluctuation standard deviations in the surface layer in low-wind conditions

In this work a formulation for the standard deviations of the wind-velocity fluctuations in the atmospheric surface layer is assessed for heterogeneous conditions and with a particular focus on calm wind regime. Starting from a standard formulation used in the devoted literature, its empirical coefficients are estimated by analysing three sets of surface-layer observed data. The possibility of inferring a formula for these coefficients as functions of the wind speed is investigated. The curves of the standard deviations as functions of the stability show different behaviours depending on the set of coefficients used, even if the values of these do not affect the overall statistical agreement between predicted and observed standard deviations. Referring to typical literature values of the coefficients, it is shown that the agreement certainly improves when distinguishing them for two wind-speed regime, low-wind and windy.     

The continuum and line spectra of SGR 1806-20 bursts

The defining property of Soft Gamma Repeaters is the emission of short, bright bursts of X-rays and soft γ-rays. Here we present the continuum and line spectral properties of a large sample of bursts from SGR 1806-20, observed with the Proportional Counter Array (PCA) onboard the Rossi X-ray Timing Explorer (RXTE). Using 10 trail spectral models (5 single and 5 two component models), we find that the burst continua are best fitted by the single component models: cutoff power-law, optically thin bremsstrahlung, and simple power-law. Time resolved spectroscopy show that there are two absorption lines at ∼5 keV and 20 keV in some bursts. The lines are relatively narrow with 90% upper limit on the line widths of 0.5–1.5 keV for the 5 keV feature and 1–3 keV for the 20 keV feature. Both lines have considerable equivalent width of 330–850 eV for the 5 keV feature and 780–2590 eV for the 20 keV feature. We examined whether theses spectral lines are dependent upon the choice of a particular continuum model and find no such dependence. Besides, we find that the 5 keV feature is pronounced with high confidence in the cumulative joint spectrum of the entire burst sample, both in the individual detectors of the PCA and in the co-added detectors spectrum. We confront the features against possible instrumental effects and find that none can account for the observed line properties. The two features do not seem to be connected to the same physical mechanism because (1) they do not always occur simultaneously, (2) while the 5 keV feature occurs at about the same energy, the 20 keV line centroid varies significantly from burst to burst over the range 18–22 keV, and (3) the centroid of the lines shows anti-correlated red/blue shifts. The transient appearance of the features in the individual bursts and in portions of the same burst, together with the spectral evolution seen in some bursts point to a complex emission mechanism that requires further investigation.      

X-ray observations of PSR B0355+54 and its pulsar wind nebula

We present X-ray data of the middle-aged radio pulsar PSR B0355+54. The XMM-Newton and Chandra observations show not only emission from the pulsar itself, but also compact diffuse emission extending ∼50″ in the opposite direction to the pulsar’s proper motion. Our analysis also indicates the presence of fainter diffuse emission extending ∼5′ from the point source. The morphology of the diffuse component is similar to the ram-pressure confined pulsar wind nebulae detected for other sources. We find that the compact diffuse component is well-fitted with a power-law, with an index that is consistent with the values found for other pulsar wind nebulae. The core emission from the pulsar can be characterized with a thermal plus power-law fit, with the thermal emission most likely originating in a hot polar cap.     

Phase Diagram in Asteroidal Motion

In order to study the dynamical behaviour of asteroids in commensurability with a planet, we propose a phase diagram obtained by short computer time. We test this numerical procedure by analyzing the behaviour of real and fictitious asteroids in first order commensurabilities with Jupiter. We have also studied the evolution time of the orbital elements and other variables to compare these results with those obtained in the phase diagram. The results obtained with our numerical technique were compared to similar results previously obtained by other authors. This revised version was published online in July 2006 with corrections to the Cover Date.     

Testing the public’s response to receiving severe flood warnings using simulated cell broadcast

Natural Hazards - European Governments must implement a public alerting system to reach mobile phone users affected by major emergencies and disasters by June 2022. Cell Broadcast is used to issue...     

Revision of the planktonic foraminiferal biostratigraphy of the Voirons Flysch (Chablais Prealps,Haute-Savoie,France)

The ages obtained from planktonic foraminiferal assemblages retrieved from two exposures in the Gurnigel Flysch and from the re-examination of similar material gathered by previous researchers from the Voirons Flysch reveal only minor discrepancies with previous studies based on nannofossil biostratigraphy. In contrast, major divergences between this work and previous studies on the Voirons Flysch also based on planktonic foraminifera have been identified. They are generally related to distinct approaches in species classification and the use of different zonal schemes. Based on our data, the age of the Voirons Flysch extends from the Early Eocene (planktonic foraminiferal zone P7) to the Middle Eocene (planktonic foraminiferal zone P12). Contrasting with claims made in earlier studies, no specimen of Late Eocene or Early Oligocene age has been observed in the revised material. However, we cannot exclude a younger age (possibly Late Eocene) for the upper portion of this flysch from which we did not revise any sample. Thus, more research and sampling are needed to resolve this question. The palaeogeographic origin of the Voirons-Wägital complex as well as the sedimentation history of these flyschs need now to be re-evaluated in light of this revised biostratigraphic data.     

High-resolution monitoring of water temperature and oxygen concentration in Lake Murten (Switzerland)

Lake Murten is located in the Lake District in western Switzerland and so far, it has been poorly investigated. The Environmental Service of Fribourg (SEn) has monitored this lake once a month for several years by water profiles (water temperature, pH, dissolved oxygen, conductivity) at its deepest part. The SEn identified the stratification of water masses as one of the main causes for oxygen consumption in the hypolimnion. In the present study, a Lander System was deployed in Lake Murten from April to September 2015 at 20 m depth at the northwestern part of the lake to monitor water temperature and dissolved oxygen at higher resolution (30 s interval). These records were compared with time series of atmospheric parameters like atmospheric temperature, wind speed and precipitation. A clear correlation of lake temperatures with wind speed was observed during the Spring and Autumn. The water mass stratification evolved through the season and reached its peak during Summer, preventing surface turbulences to reach the deeper part (20 m) of the water column and to partially oxygenate the metalimnion.     

Biostratigraphy of large benthic foraminifera from Hole U1468A (Maldives): a CT-scan taxonomic approach

Large benthic foraminifera are important components of tropical shallow water carbonates. Their structure, developed to host algal symbionts, can be extremely elaborate and presents stratigraphically-significant evolutionary patterns. Therefore their distribution is important in biostratigraphy, especially in the Indo-Pacific area. To provide a reliable age model for two intervals of IODP Hole U1468A from the Maldives Inner-Sea, large benthic foraminifera have been studied with computed tomography. This technique provided 3D models ideal for biometric-based identifications, allowing the upper interval to be placed in the late middle-Miocene and the lower interval in the late Oligocene.