Ferromanganese Nodules and Crusts from the Christmas Island Region,Indian Ocean

A sampling expedition has shown that largely hydrogenetic marine ferromanganese deposits occur in the Christmas Island region south of Java (~10°S), as small nodules on seamount slopes and abyssal plains (red clay), and as thick crusts on volcanic ridges and seamounts. Vernadite is dominant, with birnessite, jacobsite and todorokite common. Nodules were recovered in 25% of free-fall grab stations in water 4600-5900 m deep, and are not abundant where present. The nodules average 9.6% Fe, 19.7% Mn, 0.51% Ni, 0.49% Cu, and 0.12% Co. Crusts are common in water 1450-3700 m deep, with average deposition rates of 1-1.5 mm / m.y. The crusts average 13.9% Fe, 16.2% Mn, 0.35% Ni, 0.11% Cu, and 0.44% Co. Cobalt grades are higher (~0.8%) in shallower water ( < 2500 m), so future exploration should concentrate on depths of 500-1500 m near the oxygen minimum zone.     

Inconstancy in predator/prey ratios in Quaternary large mammal communities of Italy, with an appraisal of mechanisms

Constancy in predator/prey ratio (PPR) is a controversial issue in ecological research. Published reports support both constancy and inconstancy of the ratio in animal communities. Only a few studies, however, specifically address its course through time. Here we study the course of predator/prey ratio in communities of large Plio-Pleistocene mammals in Italy. After controlling for taphonomic biases, we find strong support for PPR inconstancy through time. Extinction, dispersal events, and differences in body size trends between predators and their prey were found to affect the ratio, which was distributed almost bimodally. We suggest that this stepwise dynamic in PPR indicates changes in ecosystem functioning. Prey richness was controlled by predation when PPR was high and by resources when PPR was low.     

La scintillazione delle stelle nella previsione del tempo

Riassunto Richiamate brevemente le conoscenze fondamentali sulla scintillizzazione stellare, si espongono i principi generali di un procedimento inteso a ricavare elementi d'integrazione alle osservazioni sinottiche per la formulazione del presagio meteorico locale, partendo dalla accurata e sistematica misura della scintillazione stessa. Lo studio ha carattere preliminare, contenendo considerazioni generali la cui applicazione dovrà trovare conferma dallo sviluppo delle relative osservazioni.

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Zusammenfassung Nach einem Überblick über die Entwicklung unserer Kenntnissen zur Erklärung des Funkelns der Sterne, gibt der Verf. die allgemeinen Richtlinien einer Methode, welche, stützend auf systematischen Beobachtungen dieser Erscheinung, die synoptischen Verfahren der Wettervorhersage unterstützen und ergänzen kann. Die Schrift gilt als vorläuflge Mitteilung, besonders in Anbetrachtung der Notwendigkeit einer entsprechenden Entwicklung und Verfeinerung der Beobachtungen.

     

Performance of masonry buildings during the Emilia 2012 earthquake

The earthquake sequence started on May \(20\) th 2012 in Emilia (Italy) affected a region where masonry constructions represent a large part of the existing building stock and the construction of new modern masonry buildings is a common practice. The paper is focused on the performance of common architectural configurations, typical for residential or business use. The large majority of old masonry buildings is made of fired clay bricks. The seismic performance of these buildings is particularly interesting since major past earthquakes in Italy affected areas with mainly stone masonry structures. Apart from examples showing systematic or peculiar structural deficiencies governing the vulnerability of several buildings, the overall seismic performance of these structures to repeated shaking, with PGA as large as 0.25–0.3 g was rather good, despite the major part of them were only conceived for carrying vertical loads. In fact, seismic design is mandatory in the area only since 2003. Modern low-rise masonry buildings erected after this date and incorporating seismic design and proper detailing resulted in most cases practically undamaged. The examples reported in the paper allow an evaluation of the superior performance of seismically designed modern masonry buildings in comparison to older ones.     

Seagrass importance for a small-scale fishery in the tropics: The need for seascape management

Small-scale fisheries (SSF) in tropical seascapes (mosaics of interconnected mangroves, seagrasses and corals) are crucial for food and income. However, management is directed mostly to corals and mangroves. This research analyzes the importance of seagrasses compared to adjacent ecosystems in Chwaka Bay, Zanzibar, Tanzania. Using fish landings; the study investigated: location of fishing effort, fish production (biomass and species), and monetary benefits (aggregated value and per capita income). Seagrasses were the most visited grounds providing highest community benefits. Per capita benefits were equivalent to those from corals and mangroves. All three habitats provided income just above extreme poverty levels; however catches from seagrass appeared more stable. Seagrass are key ecosystems supporting SSF and protection and management are urgently needed. Adoption of a seascape approach considering all ecosystems underpinning SSF and the social aspects of fishing and a shift in emphasis from pure conservation to sustainable resource management would be desirable.     

Effects of Amazon basin deforestation on regional atmospheric circulation and water vapor transport towards tropical South America

The water cycle over the Amazon basin is a regulatory mechanism for regional and global climate. The atmospheric moisture evaporated from this basin represents an important source of humidity for itself and for other remote regions. The deforestation rates that this basin has experienced in the past decades have implications for regional atmospheric circulation and water vapor transport. In this study, we analyzed the changes in atmospheric moisture transport towards tropical South America during the period 1961–2010, according to two deforestation scenarios of the Amazon defined by Alves et al. (Theor Appl Climatol 100(3-4):337–350, 2017). These scenarios consider deforested areas of approximately 28% and 38% of the Amazon basin, respectively. The Dynamic Recycling Model is used to track the transport of water vapor from different sources in tropical South America and the surrounding oceans. Our results indicate that under deforestation scenarios in the Amazon basin, continental sources reduce their contributions to northern South America at an annual scale by an average of between 40 and 43% with respect to the baseline state. Our analyses suggest that these changes may be related to alterations in the regional Hadley and Walker cells. Amazon deforestation also induces a strengthening of the cross-equatorial flow that transports atmospheric moisture from the Tropical North Atlantic and the Caribbean Sea to tropical South America during the austral summer. A weakening of the cross-equatorial flow is observed during the boreal summer, reducing moisture transport from the Amazon to latitudes further north. These changes alter the patterns of precipitable water contributions to tropical South America from both continental and oceanic sources. Finally, we observed that deforestation over the Amazon basin increases the frequency of occurrence of longer dry seasons in the central-southern Amazon (by between 29 and 57%), depending on the deforestation scenario considered, as previous studies suggest.     

Un procedimento per l'aggiustamento delle grandi triangolazioni

Riassunto In una nota diA. Marussi è stato rilevato che se, dopo aver compensato una triangolazione con le sole condizioni intrinseche, si impongono ulteriori condizioni come la coincidenza di alcuni vertici in punti prefissati, è possible determinare con sufficiente precisione le coordinate dei rimanenti vertici attraverso corrispondenze analitiche che soddisfino le condizioni di contorno e col requisito di limitare gli errori lineari e angolari. — L'Autore della presente nota propone una nuova corrispondenza, cioè quella atta a rappresentare le deformazioni di una membrana o rete elastica sottoposta ad assumere una data configurazione; stabilisce le equazioni per la rete elastica piana e sferica; mette in evidenza come il principio fisico della minima energia e quello matematico dei minimi quadrati conducano alle medesime equazioni.

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Summary A. Marussi has pointed out that if, after having compensated a triangulation with the intrinsic conditions only, we impose further conditions as the coincidence of some vertex in prefixed points, we can determinate the coordinates of the other vertex: that happens through analytical connections fulling contour conditions and limiting linear and angular errors.The present Author proposes a new connection, which is apt to represent the deformations of an elastic network which is to get a given configuration. He fixes the equations for the spherical and plane networks; points out how the physical principle of the least energy and the mathematical one of the least squares may give the same equations.