518 research outputs found
Phosphorus solubility in basaltic glass: limitations for phosphorus immobilization in glass and glass-ceramics
The composition of sewage sludge from urban wastewater treatment plants is simulated using P-doped basalts. Electron microscopy analyses show that the solubility of P in the basaltic melt is limited by the formation of a liquid-liquid immiscibility in the form of an aluminosilicate phase and a Ca-Mg-Fe-rich phosphate phase. The rheological behavior of these compositions is influenced by both phase separation and nanocrystallization. Upon a thermal treatment, the glasses will crystallize into a mixture of inosilicates and spinel-like phases at low P contents and into Ca-Mg-Fe phosphate at high P contents. Hardness measurements yield values between 5.41 and 7.66 GPa, inside the range of commercial glasses and glass-ceramics. Leaching affects mainly unstable Mg2+-PO43- complexes
QuickXsort: Efficient Sorting with n log n - 1.399n +o(n) Comparisons on Average
In this paper we generalize the idea of QuickHeapsort leading to the notion
of QuickXsort. Given some external sorting algorithm X, QuickXsort yields an
internal sorting algorithm if X satisfies certain natural conditions.
With QuickWeakHeapsort and QuickMergesort we present two examples for the
QuickXsort-construction. Both are efficient algorithms that incur approximately
n log n - 1.26n +o(n) comparisons on the average. A worst case of n log n +
O(n) comparisons can be achieved without significantly affecting the average
case.
Furthermore, we describe an implementation of MergeInsertion for small n.
Taking MergeInsertion as a base case for QuickMergesort, we establish a
worst-case efficient sorting algorithm calling for n log n - 1.3999n + o(n)
comparisons on average. QuickMergesort with constant size base cases shows the
best performance on practical inputs: when sorting integers it is slower by
only 15% to STL-Introsort
The influence of reactant consumption on the critical conditions for homogeneous thermal explisions
The spatially homogeneous model of a high activation energy thermal explosion is studied when the heat loss parameter a is close to the classically-defined critical value a = e. Asymptotic solutions are developed which describe the time- history of the temperature and reactant depletion. It is shown that there is a critical time period, large with respect to the characteristic conduction time, in which the temperature variation is described by a Riccati equation. The solution properties of this nonlinear equation permit one to define a value of A = a — e which separates subsequent subcritical and supercritical behaviour
Latency-aware resource orchestration in SDN-based packet over optical flexi-grid transport networks
In the upcoming 5G networks and following
the emerging Software Defined Network/Network
Function Virtualization (SDN/NFV) paradigm, demanded
services will be composed of a number of
virtual network functions that may be spread across
the whole transport infrastructure and allocated in
distributed Data Centers (DCs). These services will
impose stringent requirements such as bandwidth
and end-to-end latency that the transport network
will need to fulfill. In this paper, we present an orchestration
system devised to select and allocate virtual
resources in distributed DCs connected through a
multi-layer (Packet over flexi-grid optical) network.
Three different on-line orchestration algorithms are
conceived to accommodate the incoming requests by
satisfying computing, bandwidth and end-to-end latency
constraints, setting up multi-layer connections.
We addressed end-to-end latency requirements by
considering both network (due to propagation delay)
and processing delay components. The proposed algorithms
have been extensively evaluated and assessed
(via a number of figures of merit) through experimental
tests carried out in a Packet over Optical
Flexi-Grid Network available in the ADRENALINE
testbed with emulated DCs connected to it.This work has been partially funded by the EC H2020 5GTransformer Project (grant No. 761536)
Suitable conditions for natural regeneration in variable retention harvesting of southern Patagonian Nothofagus pumilio forests
Background: Variable retention (aggregated and dispersed retention) harvesting proposed for Nothofagus pumilio was designed for timber purposes and biodiversity conservation. Harvesting by opening canopy generates different microenvironments and creates contrasting conditions for seedling establishment, growth, and eco-physiology performance due to synergies (positives or negatives) with biotic and abiotic factors. This study evaluated the regeneration in different microenvironment conditions within managed stands during 5 years after harvesting. Remnant forest structure after harvesting and different microenvironments were characterized in managed stands, where 105 regeneration plots were measured (3 stands × 7 microenvironments × 5 replicas). We characterized the seedling bank, as well as growth and ecophysiology performance of the regeneration. Univariate and multivariate analyses were conducted for the comparisons.
Results: Microenvironments offered different environmental conditions for natural regeneration (soil moisture and light availability). Seedling under debris and dicot plants showed better eco-physiological performance, establishment, and growth than plants growing under monocots or located in the dispersed retention without the protection of other understory plants. The most unfavorable microenvironment conditions were high canopy cover of remnant trees (inside the aggregates or close to trees in the dispersed retention) and heavily impacted areas (skidder extraction roads).
Conclusions: Favorable microenvironments in the harvested areas will improve the natural recruitment, growth, and eco-physiology performance of the natural regeneration after harvesting. It is necessary to develop new silvicultural practices that decrease the unfavorable microenvironments (e.g., road density or excessive woody accumulation), to assure the success of the proposed silvicultural method.EEA Santa CruzFil: Toro Manríquez, Mónica D.R. Centro Austral de Investigaciones Científicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Cellini, Juan Manuel. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Laboratorio de Investigaciones en Maderas; ArgentinaFil: Lencinas, María Vanessa. Centro Austral de Investigaciones Científicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina. Universidad Nacional de la Patagonia Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Peña Rojas, Karen A. Universidad de Chile. Facultad de Ciencias Forestales y de Conservación de la Naturaleza. Departamento de Silvicultura y Conservación de la Naturaleza; ChileFil: Martínez Pastur, Guillermo José. Centro Austral de Investigaciones Científicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
IMPORTANCE OF DIETARY TAURINE AND SELENIUM ON GROWTH AND SURVIVAL OF ATLANTIC BLUEFIN TUNA Thunnus thynnus LARVAE
One of the most important bottleneck in the farming of Atlantic bluefin tuna (ABT) is the growth and survival during the larval rearing phase, mainly related with the diet quality. For the last ten years the Spanish Institute of Oceanography (IEO) in Mazarrón (Murcia, SE Spain) has developed a technique for ABT larval rearing and juvenile production. Taurine and selenium are essential water soluble compounds in live preys and inert diets for ABT larvae and juveniles. To know the importance of dietary taurine and selenium on growth and survival of ABT larvae, two experiments have been carried out with different taurine (Exp1) and selenium (Selplex® ) (Exp2) doses added to rotifers enriched with ALGAMAC 3050® . Both experiments were finished at 14 days post hatching. ABT fertilized eggs were collected from captive breeders spawning spontaneously in floating cages in the area. The eggs, transported to the IEO facilities, were quantified, cleaned, selected by buoyancy and distributed randomly in 1400 L fiber cylindrical glass tanks at a density of 10 ABT eggs per liter, whereas prey density was maintained at 5 rotifers per mL. Temperature ranges were: 24.0±0.5ºC and 26.0±0.5ºC for Exp1 and Exp2, respectively. Fig 1 shows the growth results in size for both experiments at 14 dph. Survival in both cases was close to 10% with no significant differences due to the different treatments. The lowest growth in size was observed in larvae fed dose 0 in both experiments Standard length average (mm ± confidence intervals) in Exp1 and Exp2 at 14 dph. Letters indicate statistically significant differences (95%
Knowledge arising from long-term research of variable retention harvesting in Tierra del Fuego: where do we go from here?
Nothofagus pumilio forests in Tierra del Fuego are the southernmost forests in the world, where extreme climate conditions represent a challenge to attain sustainable forest management. Retention forestry was proposed as an alternative to increase the species conservation in managed stands. Here, we synthetized results related to the implementation of a variable retention harvesting based on a combination of aggregate patches and dispersed retention during the last 18 years comparing with other silviculture proposals (e.g., shelterwood cuts) and control treatments (primary unmanaged forests). We summarized the results for (i) sawmill operations, (ii) timber yield, (iii) overstory stability, (iv) forest structure, (v) microclimate and natural cycles, (vi) natural regeneration dynamics (flowering, seeding, foraging, recruitment, growth, and mortality), and (vii) biodiversity (mammals, understory plants, mistletoes, birds, arthropods, mosses, lichens, and fungi). In general, aggregate patches maintained forest structure and micro-environmental variables, and slightly increased biodiversity and forest reproduction variables compared to unmanaged primary forests. On the contrary, dispersed retention decreased forest structure variables and greatly increased biodiversity (richness and abundance) when it was compared to unmanaged primary forests. Ecological conditions are influenced by variable retention harvesting, but direction and magnitude of the effect depend and differ according to retention types. Besides this, biodiversity taxa greatly differed among groups depending on retention types. In general, the species assemblages in aggregate patches were similar to those found in primary unmanaged forests, while they were significantly modified in the dispersed retention. This occurred due to (i) local extinction of some original species, (ii) the introduction of native species from the surrounding environments, or (iii) the invasion of exotic species. This silvicultural method has been a useful tool to conserve biodiversity and ecosystem functions, approaching to the balance between economy, ecology, and social requirements in the managed areas.EEA Santa CruzFil: Martínez Pastur, Guillermo José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas. Laboratorio de Recursos Agroforestales; ArgentinaFil: Rosas, Yamina Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas. Laboratorio de Recursos Agroforestales; ArgentinaFil: Toro Manríquez, Mónica D.R. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas. Laboratorio de Recursos Agroforestales; ArgentinaFil: Huertas Herrera, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas. Laboratorio de Recursos Agroforestales; ArgentinaFil: Miller, Juan A. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas. Laboratorio de Recursos Agroforestales; ArgentinaFil: Cellini, Juan Manuel. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Laboratorio de Investigaciones en Maderas; ArgentinaFil: Barrera, Marcelo Daniel. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Laboratorio de Investigaciones en Maderas; ArgentinaFil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina. Universidad Nacional de la Patagonia Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lencinas, María Vanessa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas. Laboratorio de Recursos Agroforestales; Argentin
Quasinormal modes for massless topological black holes
An exact expression for the quasinormal modes of scalar perturbations on a
massless topological black hole in four and higher dimensions is presented. The
massive scalar field is nonminimally coupled to the curvature, and the horizon
geometry is assumed to have a negative constant curvature.Comment: CECS style, 11 pages, no figures. References adde
Low-diffusion Xe-He gas mixtures for rare-event detection: electroluminescence yield
High pressure xenon Time Projection Chambers (TPC) based on secondary scintillation (electroluminescence) signal amplification are being proposed for rare event detection such as directional dark matter, double electron capture and double beta decay detection. The discrimination of the rare event through the topological signature of primary ionisation trails is a major asset for this type of TPC when compared to single liquid or double-phase TPCs, limited mainly by the high electron diffusion in pure xenon. Helium admixtures with xenon can be an attractive solution to reduce the electron diffu- sion significantly, improving the discrimination efficiency of these optical TPCs. We have measured the electroluminescence (EL) yield of Xe–He mixtures, in the range of 0 to 30% He and demonstrated the small impact on the EL yield of the addition of helium to pure xenon. For a typical reduced electric field of 2.5 kV/cm/bar in the EL region, the EL yield is lowered by ∼ 2%, 3%, 6% and 10% for 10%, 15%, 20% and 30% of helium concentration, respectively. This decrease is less than what has been obtained from the most recent simulation framework in the literature. The impact of the addition of helium on EL statistical fluctuations is negligible, within the experimental uncertainties. The present results are an important benchmark for the simulation tools to be applied to future optical TPCs based on Xe-He mixtures. [Figure not available: see fulltext.]
Perfil de aminoácidos libres en presas vivas para la alimentación de larvas de atún rojo Thunnus thynnus
The aim of this work was to study the composition in Tau and other AAL in live prey, copepods or rotifers, supplied during larval feeding of Atlantic bluefin tuna, as well as the AA profile in the larvae fed. The copepods showed a significantly higher concentration of AAL than rotifers, as the larvae fed with them. The eggs presented the highest amount of essential AAL.El objetivo de este trabajo consistió en estudiar la composición en Tau y otros AAL en las presas vivas, copépodos o rotíferos, suministradas durante la alimentación larvaria de atún rojo, así como el perfil de AA en las larvas alimentadas. Los copépodos mostraron significativamente una mayor concentración de AAL que los rotíferos, así como también en las larvas alimentadas con ellos. Los huevos presentaron la mayor cantidad de AAL esenciale
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