8,540 research outputs found
Multiple-locus heterozygosity, physiology and growth at two different stages in the life cycle of the Chilean oyster Ostrea chilensis
A random sample of 150 individuals of a laboratory-produced cohort of Ostrea chilensis Philippi, 1845 was taken at 10 and 36 mo of age to estimate physiological variables and individual heterozygosity using 4 loci (Lap, Pgi, Pgm and Ca). Juveniles of 10 mo of age showed a mean D value of 0.134 (p > 0.05) and a positive correlation between oyster size and multiple-locus heterozygosity (MLH) (p 0.05), oxygen consumption rate (p < 0.05) and MLH was found. The K2 value (standardized net growth efficiency) was positively correlated (p < 0.05) with MLH. At 36 mo a heterozygote deficiency was present with a mean value D = -0.431 (p < 0.05). No relationship between standard dry weight and MLH and also a negative correlation between the scope for growth and MLH were found. The oxygen consumption and excretion rates also showed an increase in large size individuals. The slopes for filtration and excretion rates against MLH were negative and not statistically significant. However, ingestion and absorption rates showed significant (p < 0.05) decrease with an increase in heterozygosity. The results seem to indicate that within sexually immature individuals of O. chilensis, a positive correlation between growth rate and MLH can be found, while in adults the higher energy allocation for reproduction precludes the detection of this relationship
Extended analytical study of the free-wing/free-trimmer concept
The free wing/free trimmer concept was analytically studied in order to: (1) compare the fore and aft trimmer configurations on the basis of equal lift capability, rather than equal area; (2) assess the influence of tip mounted aft trimmers, both free and fixed, on the lateral directional modes and turbulence responses; (3) examine the feasibility of using differential tip mounted trimmer deflection for lateral control; (4) determine the effects of independent fuselage attitude on the lateral directional behavior; and (5) estimate the influence of wing sweep on dynamic behavior and structural weight. Results indicate that the forward trimmer concept is feasible with the reduced size examined, but it remains inferior to the aft trimmer in every respect except structural weight. Differential motion of the aft trimmer is found to provide powerful lateral control; while the effect of fuselage deck angle is a reduction of the dutch roll damping ratio for nose-down attitudes
The Kepler problem and non commutativity
We investigate the Kepler problem using a symplectic structure consistent
with the commutation rules of the noncommutative quantum mechanics. We show
that a noncommutative parameter of the order of gives
observable corrections to the movement of the solar system. In this way,
modifications in the physics of smaller scales implies modifications at large
scales, something similar to the UV/IR mixing.Comment: 10 page
Experiences in porting mini-applications to OpenACC and OpenMP on heterogeneous systems
This article studies mini-applications—Minisweep, GenASiS, GPP, and FF—that use computational methods commonly encountered in HPC. We have ported these applications to develop OpenACC and OpenMP versions, and evaluated their performance on Titan (Cray XK7 with K20x GPUs), Cori (Cray XC40 with Intel KNL), Summit (IBM AC922 with Volta GPUs), and Cori-GPU (Cray CS-Storm 500NX with Intel Skylake and Volta GPUs). Our goals are for these new ports to be useful to both application and compiler developers, to document and describe the lessons learned and the methodology to create optimized OpenMP and OpenACC versions, and to provide a description of possible migration paths between the two specifications. Cases where specific directives or code patterns result in improved performance for a given architecture are highlighted. We also include discussions of the functionality and maturity of the latest compilers available on the above platforms with respect to OpenACC or OpenMP implementations
Light-addressable liquid crystal polymer dispersed liquid crystal
Scattering-free liquid crystal polymer-dispersed liquid crystal polymer (LCPDLC)
films are fabricated by combining a room temperature polymerizable liquid crystal (LC)
monomer with a mesogenic photosensitive LC. The morphological and photosensitive
properties of the system are analysed with polarized optical microscopy and high resolution
scanning and transmission electron microscopy. A two-phase morphology comprised of
oriented fibril-like polymeric structures interwoven with nanoscale domains of phase
separated LC exists. The nanoscale of the structures enables an absence of scattering which
allows imaging through the LCPDLC sample without optical distortion. The use of a
mesogenic monomer enables much smaller phase separated domains as compared to nonmesogenic systems. All-optical experiments show that the transmitted intensity, measured
through parallel polarizers, can be modulated by the low power density radiation (31
mW/cm2) of a suitable wavelength (532 nm). The reversible and repeatable transmission
change is due to the photoinduced trans-cis photoisomerization process. The birefringence
variation (0.01) obtained by optically pumping the LCPDLC films allow their use as an alloptical phase modulato
The Economic Case for Landscape Restoration in Latin America
Degraded lands—lands that have lost some degree of their natural productivity through human activity—account for over 20 percent of forest and agricultural lands in Latin America and the Caribbean. Some 300 million hectares of the region's forests are considered degraded, and about 350 million hectares are now classified as deforested. The agriculture and forestry sectors are growing and exerting great pressure on natural areas. With the region expected to play an increasingly important role in global food security, this pressure will continue to ratchet up. In addition, land degradation is a major driver in greenhouse gas emissions in the region. Forest and landscape restoration can offer a solution to these increasing pressures
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