430 research outputs found
Numerical simulation of a binary communication channel: Comparison between a replica calculation and an exact solution
The mutual information of a single-layer perceptron with Gaussian inputs
and deterministic binary outputs is studied by numerical simulations. The
relevant parameters of the problem are the ratio between the number of output
and input units, , and those describing the two-point
correlations between inputs. The main motivation of this work refers to the
comparison between the replica computation of the mutual information and an
analytical solution valid up to . The most relevant results
are: (1) the simulation supports the validity of the analytical prediction, and
(2) it also verifies a previously proposed conjecture that the replica solution
interpolates well between large and small values of .Comment: 6 pages, 8 figures, LaTeX fil
Three terminal capacitance technique for magnetostriction and thermal expansion measurements
An instrument has been constructed to measure a large range of
magnetostriction and thermal expansion between room temperature and 4 K in a
superconductive split-coil magnet, that allows investigation in magnetic fields
up to 12 T. The very small bulk samples (up to 1 mm in size) as well as big
ones (up to 13 mm) of the irregular form can be measured. The possibility of
magnetostriction investigation in thin films is shown. A general account is
given of both electrical and the mechanical aspects of the design of
capacitance cell and their associated electronic circuitry. A simple lever
device is proposed to increase the sensitivity twice. The resulting obtained
sensitivity can be 0.5 Angstrom. The performance of the technique is
illustrated by some preliminary measurements of the magnetostriction of
superconducting MgB2, thermal expansion of (La0.8Ba0.2)0.93MnO3 single crystal
and magnetoelastic behavior of the Ni/Si(111) and
La0.7Sr0.3CoO3/SAT0.7CAT0.1LA0.2(001) cantilevers.Comment: 6 pages, 6 figures, journal pape
Social considerations for the cultivation of industrial crops on marginal agricultural land as feedstock for bioeconomy
Marginal agricultural land (MAL) has received much attention in research and policy formation as a potential resource for cultivating biomass for energy and biobased products. However, it is still unclear whether biomass from MAL meets the requirements of social sustainability. This study develops a conceptual linkage between value-chain analysis and social life-cycle analysis (S-LCA), and assesses both positive impacts (handprints) and negative impacts (footprints). A participatory approach including interviews and surveys was used to understand views and perceptions of the relevant stakeholders. A systemic strategy was applied to analyze value-chain activities, understand challenges, and identify competitive advantages and disadvantages. For S-LCA, the variety of impacts and indicators was met through a literature review and a consistent scoring system. The cultivation of perennial crops on MAL tends to cause skepticism among stakeholders, who are concerned about long-term commitment and biodiversity risks. Annual crops, on the other hand, are perceived by all stakeholder categories as very promising opportunities across all impact categories and indicators. They can facilitate income diversification and offer smart sustainable cropping options through crop rotation, agroforestry, etc. Most of the technological pathways examined are highly innovative, have a low technological readiness level, and are still at the early market development stage. As such they are ranked by stakeholders as medium opportunities for short-term implementation. In contrast, pyrolysis to industrial heat, ethanol from switchgrass, insulation material from hemp, and biogas/biomethane from sorghum are considered opportunities with good chances of being implemented in the short term. © 2022 The Authors. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons, Ltd
Cretaceous mycelia preserving fungal polysaccharides: taphonomic and paleoecological potential of microorganisms preserved in fossil resins
The cortices of pieces of Cretaceous amber around the world commonly are constituted by networks of filamentous structures. Based on their morphological characteristics, such structures have previously been classified in different microorganismal groups. Their correct interpretation, however, is of great importance to establish the conditions of the resin's burial in the forest litter, and can provide important clues regarding the ecology and environmental conditions of Cretaceous resinous forests. Because these networks of filamentous structures present typical fungal morphological features we conducted a study in order to resolve their origin. The cortices of several pieces of Cretaceous amber from Spain were examined using light and scanning electron microscopy, energy dispersive X-ray spectroscopy, and confocal laser scanning microscopy. This is the first time that Calcofluor white and Wheat germ agglutinin conjugated with fluorescein isothiocyanate have been employed as fungal markers in amber, and their use enabled us to detect preserved polysaccharides in the filamentous structures using confocal laser scanning microscopy. These results provide the first and oldest record of ß-1,3 and ß-1,4-linked polysaccharides, and specifically N-acetylglucosamine residues from chitin in a fossil fungus preserved in amber, and to demonstrate that the networks of filamentous structures are mycelia composed of profuse hyphae of a resinicolous fungus. This type of mycelium constitutes one of the largest fungal fossil records known. Using taphonomic data, it is demonstrated that the cortices originated during the Cretaceous due to fungal growth within non-solidified resin. The fossil diagenetic degradation sequence of the fungal hyphae and the surrounding amber is described. This degradation changed the microscopic appearance of the hyphae; thus, some of the previously indicated taxonomic features of this microorganism may actually be fossil diagenetic artifacts. The paleoecological implications with regard to fungal trophic requirements and forest environmental conditions are discusse
Manganese inactivation of renal betaine aldehyde dehydrogenase from swine
Manganese is an essential micronutrient for mammals, however high manganese concentrations cause adverse health effects. Swine renal betaine aldehyde dehydrogenase catalyzes the synthesis of glycine betaine, which plays an important role in renal cells osmoregulation. In vitro inactivation of BADH was observed by incubating the purified enzyme in the presence of 1 mM MnCl2 under physiological and low ionic strength conditions. Enzyme inactivation followed first order kinetics in a monophasic process with an inactivation constant of 0.126 ± 0.011 min^-1 and 0.137 ± 0.017 at physiological and low ionic strength, respectively. Enzyme inactivation was not prevented by physiological ionic strength, nor by the substrates NAD+ and betaine aldehyde at saturated concentrations. The enzyme was reactivated with DTT and GSH. Native-PAGE of the inactivated enzyme showed no change in the tetrameric conformation. Intrinsic protein fluorescence studies demonstrated an increased exposure of the tryptophan residues to the aqueous solvent when the enzyme was incubated with Mn^2+. These results suggest that BADH inactivation by Mn^2+ may result from the oxidation of cysteines, which induces changes in the tertiary structure of the enzyme
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Multi-temporal scale analysis of complementarity between hydro and solar power along an alpine transect
Variable renewable energy sources display different space-time variability driving the availability of energy generated from these sources. Complementarity among variable renewable energies in time and space allows reducing the variability of power supply and helps matching the electricity demand curve. This work investigates the temporal structure of complementarity along an alpine transect in North-East Italy, considering a 100% renewable energy mix scenario composed by photovoltaic and run-of-the-river energy. We analyze the dominant scales of variability of variable renewable energy sources and electricity demand. In addition, we introduce a new metric, the wavelet-based complementarity index, to quantify the potential complementarity between two different energy sources. We show that this index varies at different temporal scales and it helps explaining the discrepancy between demand and supply in the study area. Continuous and discrete wavelet analyses are applied to assess the energy balance variability at multiple temporal scales and to identify the optimal mix of renewable energies, respectively. This work describes therefore an effective approach to investigate the temporal-scale dependency of the variance in the energy balance and can be further extended to different and more complex situations
Transverse magnetization in Cu/Ni/Cu epitaxial nanorings
The micromagnetic structure in epitaxial (001)-oriented Cu/Ni(14 nm)/Cu rings fabricated by electron beam and focused ion beam lithographies with external diameter of 3 µm and linewidths between 100 and 500 nm is presented. We found that a state with radial orientation of the magnetization prevails at remanence. The evaluation of the magnetoelastic, magnetocrystalline and magnetostatic energies shows that a value as low as 1.5 × 10-3 for the anisotropic relaxation of the in-plane strain components is enough to induce an effective radial easy magnetization direction
On the Tail of the Overlap Probability Distribution in the Sherrington--Kirkpatrick Model
We investigate the large deviation behavior of the overlap probability
density in the Sherrington--Kirkpatrick model from several analytical
perspectives. First we analyze the spin glass phase using the coupled replica
scheme. Here generically
, and we compute the first correction to the expansion of \A
in powers of . We study also the case, where is know
exactly. Finally we study the paramagnetic phase, where exact results valid for
all 's are obtained. The overall agreement between the various points of
view is very satisfactory. Data from large scale numerical simulations show
that the predicted behavior can be detected already on moderate lattice sizes.Comment: 18 pages including ps figure
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