Search results for "Cuba."

Assessing the efficacy of direct conservation interventions: clutch protection of the leatherback marine turtle in the Dominican Republic

2014

AbstractThe beaches of Jaragua National Park in the Dominican Republic are the country's last known major nesting site for the leatherback marine turtle Dermochelys coriacea. This nesting aggregation is threatened by widespread illegal egg take, and clutch relocation and artificial incubation have been carried out as protection measures since 1974. We assess the efficacy of such efforts and investigate how artificial incubation may be influencing the success and sex ratios of clutches. We compare hatching success, incubation duration and embryo mortality in in-situ clutches (n = 43) with those incubated artificially at sites in the east and west of the Park (n = 35 and n = 31, respectively)…

Hatching and viability of rotifer diapausing eggs collected from pond sediments

2006

SUMMARY 1. Planktonic rotifers inhabiting variable environments produce diapausing eggs that accumulate in the sediment of lakes and ponds, forming egg banks that may withstand adverse periods. A common assumption in zooplankton diapausing egg bank studies is to count as viable all eggs in the sediment that look healthy. This assumption should be challenged by asking how effectively ‘healthy-looking’ eggs represent viable eggs. 2. In this study, viability of more than 1100 ‘healthy-looking’ diapausing eggs belonging to the Brachionus plicatilis species complex was assessed in a laboratory hatching experiment. Eggs were collected at different depths from sediment cores obtained from 15 ponds…

Innovation Dynamics in Space: Local Actors and Local Factors

1997

This paper addresses the issue of technogenesis and its geographical pattern. It aims to offer both a general analysis framework and a test on innovation data from several European cities. This framework is mainly built on the product life-cycle and the incubation approach. On the basis of this framework, it is argued that the phases of an industrial life-cycle have several firm-specific effects. First, these phases influence innovativeness and thus profit levels, output and employment of firms in a spatially distinct way. Second, the phases of the life-cycle mirror the importance of local factors for innovations, and third, they affect strategic decisions of firms, inter alia by influencin…

Ecuba e l'abuso del potere

2009

Cluster simulations of structural transformations in yellow arsenic

2001

Abstract Yellow arsenic (y-As) consists of tetrahedral As4 molecules that may be packed in some amorphous and crystalline structures. Like many other arsenic structures, y-As is metastable and undergoes irreversible transitions (polymerization) under irradiation. The process of y-As polymerization, which is observed experimentally, usually leads to the formation of amorphous arsenic (a-As) possessing a continuous random network structure. Our previous quantum chemical simulation for an eight-atom cluster model performed using semi-empirical CNDO/BW approach, combined with optimization technique of cyclic coordinate descent, have shown a formation of molecular dimers due to breaking of one b…

EGTA treatment causes the synthesis of heat shock proteins in sea urchin embryos.

2000

Paracentrotus lividus embryos, at post-blastular stage, when subjected to a rise in temperature from physiologic (20 degrees C) to 31 degrees C, synthesize a large group of heat shock proteins (hsps), and show a severe inhibition of bulk protein synthesis. We show, by mono- and two-dimensional electrophoresis, that also EGTA (ethylene glycol-bis[beta-aminoethyl ether] tetraacetic acid) treatment induces in sea urchin embryos both marked inhibition of bulk protein synthesis and the synthesis of the entire set of hsps. Furthermore, EGTA-treated sea urchin embryos are able to survive at a temperature otherwise lethal (35 degrees C) becoming thermotolerant. Because incubation with a different c…

Behavioural responses of breeding arctic sandpipers to ground-surface temperature and primary productivity

2021

Most birds incubate their eggs, which requires time and energy at the expense of other activities. Birds generally have two incubation strategies: biparental where both mates cooperate in incubating eggs, and uniparental where a single parent incubates. In harsh and unpredictable environments, incubation is challenging due to high energetic demands and variable resource availability. We studied the relationships between the incubation behaviour of sandpipers (genus Calidris) and two environmental variables: temperature and a proxy of primary productivity (i.e. NDVI). We investigated how these relationships vary between incubation strategies and across species among strategies. We also stud…

Are agricultural soils under a continental temperate climate susceptible to episodic reducing conditions and increased leaching of phosphorus?

2012

International audience; Soil science research has probably underestimated the significance that short-term, episodic cycles of reduction and oxidation has had on phosphorus (P) reactivity. Here, the effects of eleven pulsed reduction-oxidation (including wet-dry) cycles on soil P dynamics are compared for 12 soils having contrasting properties and all overfertilised with respect to P. The laboratory based incubation conditions attempted to simulate transient waterlogging of the soil profile and involved repeated sampling and analysis of both the solution and solid phase P forms. An initial increase in P concentration in solution that occurred up to and including the fourth full cycle was fo…

Release of phosphorus under reducing and simulated open drainage conditions from overfertilised soils

2014

Does removal of cations from soil solution during soil reduction stimulate phosphorus (P) release? An ion-exchange resin system was employed to provide a sink during the incubation of twelve soils under fully reducing conditions. This experimental design was considered to better simulate the loss of ions likely to occur under field conditions than more routine batch type closed extraction systems where solutes build-up in the extract solution. The small solute concentrations that remain in the equilibrating solution suggest the mixed resin system acted as an effective sink over the whole experimental period. By maintaining a small P concentration the resin system mimics soil drainage condit…

Effects of solid–liquid separation on recovering residual methane and nitrogen from digested dairy cow manure

2006

The feasibility of optimizing methane and nitrogen recovery of samples obtained from farm biogas digester (35 degrees C) and post-storage tank (where digested material is stored for 9-12 months) was studied by separating the materials into different fractions using 2, 1, 0.5 and 0.25 mm sieves. Mass-balances revealed that digested material mainly consists of0.25 mm (60-69%) and2 mm (18-27%) fractions, while fractions between 2 and 0.2 mm made the rest. Incubation of solid fractions0.25 mm of digester material at 35 degrees C resulted in specific methane yields of 0.060-0.085 m(3)kg(-1) volatile solids (VS) during initial 30-50 d and 0.16-0.18 m(3)kg(-1)VS at the end of 340 d incubation. Sim…