1,581,997 research outputs found
Floristic Composition, Structural Analysis and Socio-economic Importance of Legume Flora of the Commune of Mayahi, Niger, West Africa
Floristic assessment plays a crucial role in managing and conserving phytodiversity. Thisstudy tried to determine the floristic composition, woody structure and socio-economic importance of the legume flora in the commune of Mayahi. We used plot method based on systematic sampling approach to inventory legume species within the parklands in September 2012. We recorded 55 legume species belonging to 24 genera in 56 relevés. Fabaceae is the dominant family among the legume botanical families in the parklands of the commune of Mayahi. The average woody legume density is 62 individuals per hectare in the commune of Mayahi. The woody legume species of highest average density are Faidherbia albida and Piliostigma reticulatum. While the total basal area of legumes of the commune is 1.12m2 / ha in the Mayahi commune. The crown cover varies according to the vegetation types but it is higher in the Goulbi N\u27kaba forest reserve. Legume flora provides a myriad of benefits to the people of Mayahi. The present study recommends furtherresearch that examines the impact of human activities on the legume flora of the parklands in the commune of Mayahi
Structural Refinement for the Modal nu-Calculus
We introduce a new notion of structural refinement, a sound abstraction of
logical implication, for the modal nu-calculus. Using new translations between
the modal nu-calculus and disjunctive modal transition systems, we show that
these two specification formalisms are structurally equivalent.
Using our translations, we also transfer the structural operations of
composition and quotient from disjunctive modal transition systems to the modal
nu-calculus. This shows that the modal nu-calculus supports composition and
decomposition of specifications.Comment: Accepted at ICTAC 201
The structural organization and protein composition of lens fiber junctions.
The structural organization and protein composition of lens fiber junctions isolated from adult bovine and calf lenses were studied using combined electron microscopy, immunolocalization with monoclonal and polyclonal anti-MIP and anti-MP70 (two putative gap junction-forming proteins), and freeze-fracture and label-fracture methods. The major intrinsic protein of lens plasma membranes (MIP) was localized in single membranes and in an extensive network of junctions having flat and undulating surface topologies. In wavy junctions, polyclonal and monoclonal anti-MIPs labeled only the cytoplasmic surface of the convex membrane of the junction. Label-fracture experiments demonstrated that the convex membrane contained MIP arranged in tetragonal arrays 6-7 nm in unit cell dimension. The apposing concave membrane of the junction displayed fracture faces without intramembrane particles or pits. Therefore, wavy junctions are asymmetric structures composed of MIP crystals abutted against particle-free membranes. In thin junctions, anti-MIP labeled the cytoplasmic surfaces of both apposing membranes with varying degrees of asymmetry. In thin junctions, MIP was found organized in both small clusters and single membranes. These small clusters also abut against particle-free apposing membranes, probably in a staggered or checkerboard pattern. Thus, the structure of thin and wavy junctions differed only in the extent of crystallization of MIP, a property that can explain why this protein can produce two different antibody-labeling patterns. A conclusion of this study is that wavy and thin junctions do not contain coaxially aligned channels, and, in these junctions, MIP is unlikely to form gap junction-like channels. We suggest MIP may behave as an intercellular adhesion protein which can also act as a volume-regulating channel to collapse the lens extracellular space. Junctions constructed of MP70 have a wider overall thickness (18-20 nm) and are abundant in the cortical regions of the lens. A monoclonal antibody raised against this protein labeled these thicker junctions on the cytoplasmic surfaces of both apposing membranes. Thick junctions also contained isolated clusters of MIP inside the plaques of MP70. The role of thick junctions in lens physiology remains to be determined
A generalized bayesian inference method for constraining the interiors of super Earths and sub-Neptunes
We aim to present a generalized Bayesian inference method for constraining
interiors of super Earths and sub-Neptunes. Our methodology succeeds in
quantifying the degeneracy and correlation of structural parameters for high
dimensional parameter spaces. Specifically, we identify what constraints can be
placed on composition and thickness of core, mantle, ice, ocean, and
atmospheric layers given observations of mass, radius, and bulk refractory
abundance constraints (Fe, Mg, Si) from observations of the host star's
photospheric composition. We employed a full probabilistic Bayesian inference
analysis that formally accounts for observational and model uncertainties.
Using a Markov chain Monte Carlo technique, we computed joint and marginal
posterior probability distributions for all structural parameters of interest.
We included state-of-the-art structural models based on self-consistent
thermodynamics of core, mantle, high-pressure ice, and liquid water.
Furthermore, we tested and compared two different atmospheric models that are
tailored for modeling thick and thin atmospheres, respectively. First, we
validate our method against Neptune. Second, we apply it to synthetic
exoplanets of fixed mass and determine the effect on interior structure and
composition when (1) radius, (2) atmospheric model, (3) data uncertainties, (4)
semi-major axes, (5) atmospheric composition (i.e., a priori assumption of
enriched envelopes versus pure H/He envelopes), and (6) prior distributions are
varied. Our main conclusions are: [...]Comment: Astronomy & Astrophysics, 597, A37, 17 pages, 11 figure
Composition Dependence of Structural Parameters and Properties of Gallium Ferrite
We show the effect of composition on structural and magnetic characteristics
of pure phase polycrystalline GaFeO (GFO) for compositions between
0.8 <= x <= 1.3. X-ray analysis reveals that lattice parameters of GFO exhibit
a linear dependence on Fe content in single phase region indicating
manifestation of Vegard's law. Increasing Fe content of the samples also leads
to stretching of bonds as indicated by the Raman peak shifts. Further, low
temperature magnetic measurements show that the coercivity of the samples is
maximum for Ga:Fe ratio of 1:1 driven by a competition between decreasing
crystallite size and increasing magnetic anisotropy.Comment: 15 pages with 4 figure
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Scanning Raman spectroscopy for characterizing compositionally spread films
Composition-spread La1-xSrxMnO3 thin films were prepared by pulsed laser deposition technique from LaMnO3 and SrMnO3 targets. The films were epitaxial with a continuous variation of the out-of-plane lattice parameter along the direction of composition gradient. Scanning Raman spectroscopy has been employed as a nondestructive tool to characterize the composition-spread films. Raman spectra showed the variation of the structural, Jahn Teller distortions and the presence of coexisting phases at particular compositions that are in agreement with the previous observation on the single-crystal samples. Raman spectra on the continuous composition-spread film also reveal the effect of disorder and strain on the compositions
Evidence for existence of Functional Monoclinic Phase in Sodium Niobate based Solid Solution by Powder Neutron Diffraction
We have carried out systematic temperature-dependent neutron diffraction
measurements in conjunction with dielectric spectroscopy from 6 to 300 K for
sodium niobate based compounds (1-x) NaNbO3 -xBaTiO3 (NNBTx). The dielectric
constant is measured both as a function of temperature and frequency. It shows
an anomaly at different temperatures in cooling and heating cycles and exhibits
a large thermal hysteresis of 150 K for the composition x=0.03. The dielectric
constant is found to be dispersive in nature and suggests a relaxor
ferroelectric behavior. In order to explore structural changes as a function of
temperature, we analyzed the powder neutron diffraction data for the
composition x=0.03 and 0.05, respectively. Drastic changes are observed in the
powder profiles near 30.6{\deg}, 32.1{\deg} and 34.6{\deg} in the diffraction
pattern below 200 K during cooling and above 190 K in heating cycles,
respectively.The disappearance of superlattice reflection and splitting in main
perovskite peaks provide a signature for structural phase transition. We
observed stabilization of a monoclinic phase (Cc) at low temperature. This
monoclinic phase is believed to provide a flexible polarization rotation and
considered to be directly linked to the high performance piezoelectricity in
materials. The thermal hysteresis for composition x=0.03 is larger than x=0.05.
This suggests that addition of BaTiO3 in NaNbO3 suppresses the thermal
hysteresis. It is also observed that the structural phase transition
temperature decreases on increasing dopant concentration.Comment: 16 Pages, 6 Figure
Dual Economies and International Total Factor Productivity Differences.
This paper argues that a significant part of measured TFP differences across countries is attributable not to technological factors that affect the entire economy neutrally, but rather, to variations in the structural composition of economies. In particular, the allocation of scarce inputs between agriculture and non-agriculture seems to be important. We provide a theory which links the institutional framework to the long-run composition of the economy, and thereby to measured TFP and income per worker. A decomposition analysis suggests that between 30 and 50 percent of the international variation in TFP can be attributed to the composition of output. Estimation exercises suggest that recent findings of a conducive effect from institutions, and to some extent, geography, on long-run prosperity and TFP, may be thus explained.dual economy; structural change; total factor productivity; institutions; geography
Provision of public goods, voting and agglomerative bias
Skill-biased technical change is identified as the driving force behind the changing skill composition in OECD countries rather than structural change. The finding is partly the result of the sectoral view taken. This paper suggests a different view which uses the production process as a starting point. The economy is divided into physica production, personal services, and intermediate services; these branches are again subdivided. Applying the resulting grid to German data from the Socio-economic Panel shows that a structural change in the production process is driving the skill composition of the German labor force.
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