Earthquake-induced reactivation of landslides under variable hydrostatic conditions: evaluation at regional scale and implications for risk assessment

Landslides - Earthquake-induced landslides represent a significant seismic hazard since they can largely increase the damage and losses due to a seismic event, an issue that must be considered in...     

Sulla variazione della densità nell'interno della terra

Riassunto L'Autore considera dapprima un geoide di rotazione di cui esprime la densità mediante sviluppo in serie di potenze del raggio vettore con i coefficienti dipendenti dalla latitudine . Risolve l'equazione di Poisson relativa al geoide, dimostra che la funzione potenziale si sviluppa in serie di potenze pari di e mette in evidenza la influenza dei termini dipendenti dalla latitudine nel rapporto fra i momenti di inerzia e nella variazione della gravità in superficie. Considera poi il geoide sferico e determina, in due esempi, l'andamento della densità, basandosi nel presupposto che l'energia del campo di gravità sia la più alta possibile compatibilmente allo stato attuale della Terra; ne risulta una densità centrale compresa fra 15 e 19.

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Summary The Author first considers a rotational geoid the density of which he introduces through potential series development of radius vector with coefficients as functions of latitude . He solves Poisson equation of the geoid, demonstrates that its potential function develops through potential series even of , points out the influence of the terms deriving from the latitude in the ratio from the inertia moments and the variation in surface gravity. Then he considers a spheric geoid and, by two demonstrations, he establishes the density, basing his theory on the assumption that gravity field energy is the highest one can trace in the present condition of the Earth; the result give a central density ranging from 15 to 19.

     

Trace element concentrations in Coastal Hawaiian waters

The objective of this work is to characterize the concentrations of selected trace elements (V, Mn, Ni, Fe, Co, Cu, Zn, Se, As, Mo, Cd, Pb, U) in diverse nearshore (50 m), coastal (1.5 km) and seawater well environments within the Hawaiian Archipelago using robust analytical methods that are appropriate for metals analyses in seawater. The sampling sites include locations having varying type, quality and quantity of freshwater input. In most coastal and nearshore cases, the trace element concentrations approximate values characteristic of offshore waters. Concentrations of trace elements in coastal waters that were enriched through either urban or agricultural inputs declined sharply within a short distance from shore; this is taken to indicate the predominant importance of physical mixing/advective processes along with particle scavenging in these dynamic areas. Trace element levels in seawater wells did not evidence any concentration trends consistent with island age suggesting little or no impact of island weathering on metal concentrations; concentration differences among wells appeared to be more dependent on well depth, redox conditions, and/or salinity. Sampling also targeted nearshore locales where ciguatera fish poisoning is prominent because of suggested linkages between trace element concentrations and aberrant dinoflagellate growth. Nearshore stations where ciguatera is prevalent failed to show clearly different trace element levels except for two prominent locales which showed elevated Mn and Fe concentrations.     

The influence of coastal dynamics on the upper limit of the Posidonia oceanica meadow

The recognized ecological importance of Posidonia oceanica, the most important seagrass of the Mediterranean Sea, makes it crucial to assess the state of health of its meadows, discriminating natural from anthropogenic impacts. In this paper, the hydrodynamic conditions at the upper limit of P. oceanica meadows along the Ligurian coast (NW Mediterranean Sea) were investigated. A relationship between the distance of the upper limit of the meadow from the shoreline and the morphodynamic domain of the beach (i.e. distinctive types of beach produced by the topography, wave climate and sediment composition) was found. A zonation of the state of the shallow portions of the meadows down the submerged beach profile was identified. Zone a, from the shoreline to the breaking limit, is naturally critical for the development of the meadow. Zone b, from the breaking limit to the closure depth, is subjected to natural and human impacts. Zone c, below the closure depth, is little influenced by coastal dynamics. This study quantifies for the first time how much the status of the shallow portions of P. oceanica meadows is dependent on coastal dynamics, which is important for their proper management.     

Microalgal Communities of the Sea Ice, Ice-Covered and Ice-Free Waters of Wood Bay (Ross Sea, Antarctica) During the Austral Summer 1993 – 94

Abstract. During the austral summer 1993 – 94, microalgal density and biomass were investigated in the sea ice, in the underlying water column, in the melt water and during the formation of the sea ice. Of the 96 taxa identified, 59 were diatoms and 32 were dinoflagellates. Among the remaining five species, Pseudopleurochloris antarctica  was very abundant both in the sea ice and in the ice-free waters. Cell densities and biomass of microalgae were higher in the bottom of the sea ice and during the formation of the ice than in the seawater, and diatoms were the dominant group at higher microalgal biomass. Among these, Entomoneis kufferathii , Chaetoceros dichaeta and Fragilariopsis species were the most common taxa.     

Questioni di ottica geometrica risolte con metodi meccanici

Riassunto Dall'analogia fra il principio ottico diFermat e quello meccanico della minima azione, l'A. ricava un metodo per determinare con mezzi meccanici: 1° la traiettoria di un raggio luminoso passante per due punti dati e separati da un lente; 2°) le superficie di lenti stigmatiche soddisfacenti a condizioni prefissate, in particolare a quelle diAbbe, Herschel.... Si accenna infine a possibili applicazioni nel campo delle lenti sferiche.

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Summary From the analogy between the optical principle ofFermat and the mechanical one of minimum action, the Author deduces a method for obtaining with mechanical devices: 1) the optical path of a light beam passing through two given points and separated by a lens; 2) the surfaces of stigmatic lenses fulfilling prefixed conditions, particularly those ofAbbe, Herschell.... Further, it is hinted at possible applications in the field of spherical lenses.

     

Beyond Copenhagen: a realistic climate policy in a fragmented world

In this paper we argue that the financial provisions of the Copenhagen Accord, if used primarily to mitigate greenhouse gas (GHGs) emissions, could compensate the lack of more energetic action on the domestic mitigation side. In order to maximize the mitigation potential, the Copenhagen Green Climate Fund (CGCF) should be transformed into the International Bank for Emissions Allowance Acquisition (IBEAA) envisaged by Bradford (2008). We estimate that 50 percent of the CGCF in 2020 (50 US billions) could finance from 2.1 to 3.3?Gt CO2-eq emission reductions, depending on the domestic mitigation effort of Annex I and Non-Annex I countries. We construct a matrix that shows the level of GHGs emissions in 2020 under all possible combinations of abatement pledges and international mitigation financing, thus highlighting a rich set of options to reach the same level of GHGs emissions in 2020.