Ephemeral rollover points and clinothem evolution in the modern Po Delta based on repeated bathymetric surveys

Reconstructions of ancient delta systems rely typically on a two-dimensional (2D) view of prograding clinothems but may miss their three-dimensional (3D) stratigraphic complexity which can, instead, be best documented on modern delta systems by integrating high-resolution geophysical data, historical cartography, core data and geomorphological reconstructions offshore. We quantitatively compare three precisely positioned, high-resolution multi-beam bathymetry maps in the delta front and pro delta sectors (0.3 to 10 m water depth) of Po di Pila, the most active of the modern Po Delta five branches. By investigating the detailed morphology of the prograding modern Po Delta, we shed new light on the mechanisms that control the topset to foreset transition in clinothems and show the temporal and spatial complexity of a delta and its pro delta slope, under the impact of oceanographic processes. This study documents the ephemeral nature of the rollover point at the transition between sandy topset (fluvial, delta plain to mouth-bar) and muddy seaward-dipping foreset deposits advancing, in this case, in >20 m of water depth. Three multibeam surveys, acquired between 2013 and 2016, document the complexity in space and time of the topset and foreset regions and their related morphology, a diagnostic feature that could not be appreciated using solely 2D, even very high-resolution, seismic profiles. In addition, the comparison of bathymetric surveys gathered with one-year lapses shows the migration of subaqueous sand dunes on the clinothem topset, the formation of ephemeral cut-and-fill features at the rollover point (few m below mean sea level), the presence of collapse depressions derived by sagging of sediments and fluid expulsion (possibly induced by storm waves) on the foreset, and splays of sand likely reflecting gravity flows on the lower foreset. Though the modern Po Delta is anthropogenic in many respects, its subaqueous clinothem can be studied as a scale model for ancient clinothems that are less resolved geometrically and far less constrained chronologically.     

Performance of a base isolator with shape memory alloy bars

A new and innovative base isolation device is introduced in this paper based on extensive research carried out by the authors and their co-workers. A prototype of the device was built and experimentally tested on the shaking table. The new base isolation device consists of two disks, one vertical cylinder with an upper enlargement sustained by three horizontal cantilevers, and at least three inclined shape memory alloy (SMA) bars. The role of the SMA bars is to limit the relative motion between the base and the superstructure, to dissipate energy by their super-elastic constitutive law and to guarantee the re-centring of the device. To verify the expected performance, a prototype was built and tested under sinusoidal waves of displacement of increasing frequency with different amplitudes. It is shown that the main feature of the proposed base isolation device is that for cyclic loading, the super-elastic behavior of the alloy results in wide load-displacement loops, where a large amount of energy is dissipated.     

Brazil’s Financial Centers in the Twenty-first Century: Hierarchy,Specialization, and Concentration

The purpose of this article is to examine how the geography of Brazil’s financial centers changed since 2000 in terms of financial center hierarchy, specialization, and spatial concentration. To address these questions, we use data on employment and mergers and acquisitions in financial and business services, complemented with data on remuneration and bank assets. Our results show that São Paulo has consolidated its dominance as Brazil’s primary financial center, with market for corporate control as an important channel of this process. Rio’s decline as a financial center, which started more than fifty years ago, has continued into this century. At the same time, Brasília has emerged as the third most important financial center of Brazil. We document the recent dynamic of this territorial division of labor, with Rio’s specialization in insurance and Brasília’s dependence on government-owned banks. Finally, we show signs that Brazil’s financial center activities might be following an inverse U-shaped pattern whereby increasing geographical concentration is followed by its slow decline. Key Words: Brazil, concentration, financial centers, São Paulo, territorial division of labor.     

Measured performance of the application of EGNOS in the road traffic sector

European Geostationary Navigation Overlay Service (EGNOS) is a satellite-based system developed to improve the performance of GPS in the European region. It not only enhances the estimated positioning accuracy but also provides an integrity solution. We assess the EGNOS performance through analysis of real measurements, performed in different road user environments. We investigate the use of the integrity concept in future Global Navigation Satellite System (GNSS)-based applications in the road environment, considering both suburban and dense urban areas. The analysis is motivated by the fact that there is an increasing number of road applications, such as billing system, transportation of dangerous goods, remote tracking of trucks and snow plows, fleet management and “pay as you go” car insurances, where the system liability has to be guaranteed. The scope of the analysis is to investigate to which extent the use of the integrity concept can be used for such purpose; the assessment is based on real measurement campaigns in representative environments, providing statistical results in terms of accuracy and integrity, and in a wider sense of the feasibility of the use of EGNOS for augmenting the reliability of GNSS positioning for road applications.     

Morphologic variability of exposed mass-transport deposits on the eastern slope of Gela Basin (Sicily channel)

The NE portion of Gela Basin in the Sicily Channel is affected by multiple slope failures originated during the late‐Quaternary. Basin sequences show evidence of stacked acoustically transparent and/or chaotic units, characterized by irregular upper surfaces, interpreted as mass‐transport deposits. The seafloor morphology also shows evidence of both old, partially buried, as well as recent slide products. Two recent slides exposed at seafloor, only 6 km apart (Twin Slides), are similar in geomorphological parameters, age and multistage evolution. Multistage failure of Twin Slides evolved from mud flows, derived from the extensive failure of less consolidated post‐glacial units, to localized slides (second stage of failure) affecting older and more consolidated materials. Although Twin Slides are very close to each other and have similar runout and fall height, they produced very dissimilar organization of the displaced masses, likely reflecting the distinct source units affected by failures. Integrating geophysical, sedimentological, structural and palaeontological data, a detailed investigation was conducted to determine the size and internal geometry of this mass‐transport complex, to explain the differentiated product and to shed light on its predisposing factors, triggers and timing.     

In‐Situ Sonication for Enhanced Recovery of Aquifer Microbial Communities

Sampling methods for characterization of microbial communities in aquifers should target both suspended and attached microorganisms (biofilms). We investigated the effectiveness and reproducibility of low‐frequency (200 Hz) sonication pulses on improving extraction efficiency and quality of microorganisms from a petroleum‐contaminated aquifer in Studen (Switzerland). Sonication pulses at different power levels (0.65, 0.9, and 1.1 kW) were applied to three different groundwater monitoring wells. Groundwater samples extracted after each pulse were compared with background groundwater samples for cell and adenosine tri‐phosphate concentration. Turbidity values were obtained to assess the release of sediment fines and associated microorganisms. The bacterial community in extracted groundwater samples was analyzed by terminal‐restriction‐fragment‐length polymorphism and compared with communities obtained from background groundwater samples and from sediment cores. Sonication enhanced the extraction efficiency up to 13‐fold, with most of the biomass being associated with the sediment fines extracted with groundwater. Consecutive pulses at constant power were decreasingly effective, while pulses with higher power yielded the best results both in terms of extraction efficiency and quality. Our results indicate that low‐frequency sonication may be a viable and cost‐effective tool to improve the extraction of microorganisms from aquifers, taking advantage of existing groundwater monitoring wells.     

Variations in the geomagnetic dipole moment during the Holocene and the past 50 kyr

All absolute paleointensity data published in peer-reviewed journals were recently compiled in the GEOMAGIA50 database. Based on the information in GEOMAGIA50, we reconstruct variations in the geomagnetic dipole moment over the past 50  kyr, with a focus on the Holocene period. A running-window approach is used to determine the axial dipole moment that provides the optimal least-squares fit to the paleointensity data, whereas associated error estimates are constrained using a bootstrap procedure. We subsequently compare the reconstruction from this study with previous reconstructions of the geomagnetic dipole moment, including those based on cosmogenic radionuclides (¹⁰Be and ¹⁴C). This comparison generally lends support to the axial dipole moments obtained in this study. Our reconstruction shows that the evolution of the dipole moment was highly dynamic, and the recently observed rates of change (5% per century) do not appear unique. We observe no apparent link between the occurrence of archeomagnetic jerks and changes in the geomagnetic dipole moment, suggesting that archeomagnetic jerks most likely represent drastic changes in the orientation of the geomagnetic dipole axis or periods characterized by large secular variation of the non-dipole field. This study also shows that the Holocene geomagnetic dipole moment was high compared to that of the preceding  40  kyr, and that  4 · 10²²  Am² appears to represent a critical threshold below which geomagnetic excursions and reversals occur.     

Forest structure of a maple old-growth stand: a case study on the Apennines mountains (Southern Italy)

In Europe, very small forest areas can be considered to be old-growth, and they are mainly located in Eastern Europe. The typical structures of old growth forests infrequently occur in Mediterranean mountainous environments, since they have been affected by human activities for centuries. This study focused on a remote and almost pure Italian maple stand located in southern Italy, which has not been managed for long time due to its inaccessibility. The effects of natural evolution on the forest stand were evaluated through the analysis of the spatial and chronological structure and the regeneration patterns, then estimating the amounts and quality of deadwood occurrence. Across the whole stand, all the trees with DBH (diameter at breast height) larger than 50 cm (LLT, large living trees) were measured (DBH and height) and age was also determined through a dendrochronological approach. The diameters observed ranged between 50 and 145 cm with ages of 120 to 250 years. The Latham index calculated for trees within the sample plot highlighted a multilayered canopy with a dominant layer of large living trees (age > 120 years). The size-class distribution of stems had a reverse-J shape, and basal area was 52 m² ha^-1. Deadwood was exclusively constituted by standing dead trees and CWD and its volume was on average 31 m³ ha^-1.Pure Italian maple forests are generally rare in Europe, and it was unexpected to find a forest stand characterized by a so complex structure with old growth attributes. The study of complex forest stand, even if small, could give precious information on the forest evolution, clarifying also diverse auto-ecological traits of tree species that usually are not common in our forests.     

A new method for specular and diffuse pseudorange multipath error extraction using wavelet analysis

Multipath remains one of the major challenges in Global Navigation Satellite System (GNSS) positioning because it is considered the dominant source of ranging errors, which can be classified into specular and diffuse types. We present a new method using wavelets to extract the pseudorange multipath in the time domain and breaking it down into the two components. The main idea is an analysis-reconstruction approach based on application of both continuous wavelet transform (CWT) and discrete wavelet transform (DWT). The proposed procedure involves the use of L1 code-minus-carrier (CMC) observable where higher-frequency terms are isolated as residuals. CMC residuals are analyzed by applying the CWT, and we propose the scalogram as a technique for discerning time–frequency variations of the multipath signal. Unlike Fourier transform, the potential of the CWT scalogram for examining the non-stationary and multifrequency nature of the multipath is confirmed as it simultaneously allows fine detection and time localization of the most representative frequencies of the signal. This interpretation of the CWT scalogram is relevant when choosing the levels of reconstruction with DWT, allowing accurate time domain extraction of both the specular and diffuse multipath. The performance and robustness of the method and its boundary applicability are assessed. The experiment was carried out using a receiver of Campania GNSS Network. The results are given in which specular multipath error is achieved using DWT level 7 approximation component and diffuse multipath error is achieved using DWT level 6 denoised detail component.     

Olive tree phenology and climate variations in the Mediterranean area over the last two decades

The flowering characteristics of plant species of economic interest and the influence of climate on them are of great importance considering the implications for fruit setting and the final harvest: Olive is one of the typical species of the Mediterranean habitat. We have investigated the timing of olive full flowering during the anthesis period and flowering intensity over a period of 20 years (1990–2009), in three major cultivation areas of the Mediterranean basin: Italy, Spain and Tunisia. The importance of these characteristics from a bioclimatic point of view is considered. The biological behaviour was studied to determine its main relationships with temperature and water availability, considering also the different sub-periods and the bio-climatic variations during the study period. The flowering dates and pollen emissions show different behaviours for the Spanish monitoring area in comparison with the other two olive cultivation areas. In the Italian and Tunisian areas, the flowering period over the last decade has become earlier by about 5 and 7 days, respectively, in comparison to the previous decade. Moreover, pollen emissions have decreased in Perugia (Italy) and Zarzis (Tunisia) over the period of 2000–2009, while in Cordoba (Spain), they showed their highest values from 2005 to 2009. The climate analysis has shown an increase in temperature, which results in an increase in the growing degree days for the growth of the olive flower structures, particularly in the more northern areas monitored. Although the olive tree is a parsimonious water consumer that is well adapted to xeric conditions, the increase in the potential evapotranspiration index over the last decade in the Italian and Tunisian olive areas might create problems for olive groves without irrigation, with a negative influence on the flowering intensity. Overall, in all of these Mediterranean monitoring areas, the summer water deficit is an increasingly more important parameter in comparison to the winter parameters, which confirms that the winter period is not as limiting as the summer period for olive tree cultivation in these Mediterranean areas.