342 research outputs found
Superintegrability on N-dimensional spaces of constant curvature from so(N+1) and its contractions
The Lie-Poisson algebra so(N+1) and some of its contractions are used to
construct a family of superintegrable Hamiltonians on the ND spherical,
Euclidean, hyperbolic, Minkowskian and (anti-)de Sitter spaces. We firstly
present a Hamiltonian which is a superposition of an arbitrary central
potential with N arbitrary centrifugal terms. Such a system is quasi-maximally
superintegrable since this is endowed with 2N-3 functionally independent
constants of the motion (plus the Hamiltonian). Secondly, we identify two
maximally superintegrable Hamiltonians by choosing a specific central potential
and finding at the same time the remaining integral. The former is the
generalization of the Smorodinsky-Winternitz system to the above six spaces,
while the latter is a generalization of the Kepler-Coulomb potential, for which
the Laplace-Runge-Lenz N-vector is also given. All the systems and constants of
the motion are explicitly expressed in a unified form in terms of ambient and
polar coordinates as they are parametrized by two contraction parameters
(curvature and signature of the metric).Comment: 14 pages. Based on the contribution presented at the "XII
International Conference on Symmetry Methods in Physics", Yerevan (Armenia),
July 2006. To appear in Physics of Atomic Nucle
Superintegrable potentials on 3D Riemannian and Lorentzian spaces with non-constant curvature
A quantum sl(2,R) coalgebra is shown to underly the construction of a large
class of superintegrable potentials on 3D curved spaces, that include the
non-constant curvature analogues of the spherical, hyperbolic and (anti-)de
Sitter spaces. The connection and curvature tensors for these "deformed" spaces
are fully studied by working on two different phase spaces. The former directly
comes from a 3D symplectic realization of the deformed coalgebra, while the
latter is obtained through a map leading to a spherical-type phase space. In
this framework, the non-deformed limit is identified with the flat contraction
leading to the Euclidean and Minkowskian spaces/potentials. The resulting
Hamiltonians always admit, at least, three functionally independent constants
of motion coming from the coalgebra structure. Furthermore, the intrinsic
oscillator and Kepler potentials on such Riemannian and Lorentzian spaces of
non-constant curvature are identified, and several examples of them are
explicitly presented.Comment: 14 pages. Based in the contribution presented at the Group 27
conference, Yerevan, Armenia, August 13-19, 200
What does the freshwater clam, Corbicula largillierti, have to tell us about chlorothalonil effects?
Chlorothalonil (CLT) is a broad spectrum, and non-systemic fungicide applied in foliar structures to prevent and treat pathogens. This compound reaches to aquatic environments and affects the biota. In this context, the main goal of this study was to assess the effects of CLT at biochemical, tissular, and individual levels of biological organization using the invasive bivalve Corbicula largillierti as a bioindicator species. Clams were exposed to different sublethal concentrations (0, 10, 20 and 50 µg. L−1 CLT) for 96 h. At biochemical level, the enzymatic activity (Glutathione-s-Transferase, Catalase, Acetyl-, Butiryl- and Carboxyl-esterases) and lipid peroxidation were measured in gills and the visceral mass. Also, the digestive gland morphometry through quantitative histological indexes was registered at the tissular level. Finally, filtering activity and burial behavior at the individual level were measured. At the highest CLT concentration, the most significant changes were observed in enzymatic activity (except for butyrylcholinesterase), lipid peroxidation and in digestive gland morphometry. It was also registered increases of the filtering activity and the latency time to burial. Most of the biomarkers assessed showed significant responses under CLT exposure. Therefore, taking into account that C. largillierti was affected by CLT, it can be expected that other species could be in a potential risk if this fungicide is present in freshwater systems.Fil: Reyna, Paola Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; ArgentinaFil: Albá, M. L.. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; ArgentinaFil: Rodriguez, Florencia Anahi. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; ArgentinaFil: Gonzalez, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Pegoraro, César Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Química; ArgentinaFil: Hued, Andrea Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; ArgentinaFil: Tatian, Marcos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; ArgentinaFil: Ballesteros, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentin
SSDSS IV MaNGA - Properties of AGN host galaxies
We present here the characterization of the main properties of a sample of 98
AGN host galaxies, both type-II and type-I, in comparison with those of about
2700 non-active galaxies observed by the MaNGA survey. We found that AGN hosts
are morphologically early-type or early-spirals. For a given morphology AGN
hosts are, in average, more massive, more compact, more central peaked and
rather pressurethan rotational-supported systems. We confirm previous results
indicating that AGN hosts are located in the intermediate/transition region
between star-forming and non-star-forming galaxies (i.e., the so-called green
valley), both in the ColorMagnitude and the star formation main sequence
diagrams. Taking into account their relative distribution in terms of the
stellar metallicity and oxygen gas abundance and a rough estimation of their
molecular gas content, we consider that these galaxies are in the process of
halting/quenching the star formation, in an actual transition between both
groups. The analysis of the radial distributions of the starformation rate,
specific star-formation rate, and molecular gas density shows that the
quenching happens from inside-out involving both a decrease of the efficiency
of the star formation and a deficit of molecular gas. All the intermediate
data-products used to derive the results of our analysis are distributed in a
database including the spatial distribution and average properties of the
stellar populations and ionized gas, published as a Sloan Digital Sky Survey
Value Added Catalog being part of the 14th Data Release:
http://www.sdss.org/dr14/manga/manga-data/manga-pipe3d-value-added-catalog/Comment: 48 pages, 14 figures, in press in RMxA
Use of sonic tomography to detect and quantify wood decay in living trees.
Premise of the studyField methodology and image analysis protocols using acoustic tomography were developed and evaluated as a tool to estimate the amount of internal decay and damage of living trees, with special attention to tropical rainforest trees with irregular trunk shapes.Methods and resultsLiving trunks of a diversity of tree species in tropical rainforests in the Republic of Panama were scanned using an Argus Electronic PiCUS 3 Sonic Tomograph and evaluated for the amount and patterns of internal decay. A protocol using ImageJ analysis software was used to quantify the proportions of intact and compromised wood. The protocols provide replicable estimates of internal decay and cavities for trees of varying shapes, wood density, and bark thickness.ConclusionsSonic tomography, coupled with image analysis, provides an efficient, noninvasive approach to evaluate decay patterns and structural integrity of even irregularly shaped living trees
Approaches in Sustainable, Biobased Multilayer Packaging Solutions
The depletion of fossil resources and the growing demand for plastic waste reduction has put industries and academic researchers under pressure to develop increasingly sustainable packaging solutions that are both functional and circularly designed. In this review, we provide an overview of the fundamentals and recent advances in biobased packaging materials, including new materials and techniques for their modification as well as their end-of-life scenarios. We also discuss the composition and modification of biobased films and multilayer structures, with particular attention to readily available drop-in solutions, as well as coating techniques. Moreover, we discuss end-of-life factors, including sorting systems, detection methods, composting options, and recycling and upcycling possibilities. Finally, regulatory aspects are pointed out for each application scenario and end-of-life option. Moreover, we discuss the human factor in terms of consumer perception and acceptance of upcycling
The simulation of molecular clouds formation in the Milky Way
Using 3D hydrodynamic calculations we simulate formation of molecular clouds
in the Galaxy. The simulations take into account molecular hydrogen chemical
kinetics, cooling and heating processes. Comprehensive gravitational potential
accounts for contributions from the stellar bulge, two and four armed spiral
structure, stellar disk, dark halo and takes into account self-gravitation of
the gaseous component. Gas clouds in our model form in the spiral arms due to
shear and wiggle instabilities and turn into molecular clouds after t\simgt
100 Myr. At the times Myr the clouds form hierarchical
structures and agglomerations with the sizes of 100 pc and greater. We analyze
physical properties of the simulated clouds and find that synthetic statistical
distributions like mass spectrum, "mass-size" relation and velocity dispersion
are close to those observed in the Galaxy. The synthetic (galactic
longitude - radial velocity) diagram of the simulated molecular gas
distribution resembles observed one and displays a structure with appearance
similar to Molecular Ring of the Galaxy. Existence of this structure in our
modelling can be explained by superposition of emission from the galactic bar
and the spiral arms at 3-4 kpc.Comment: 10 pages, 8 figure
The <i>Herschel</i> view of the massive star-forming region NGC 6334
Aims: Fundamental to any theory of high-mass star formation are gravity and turbulence. Their relative importance, which probably changes during cloud evolution, is not known. By investigating the spatial and density structure of the high-mass star-forming complex NGC 6334 we aim to disentangle the contributions of turbulence and gravity.
Methods: We used Herschel PACS and SPIRE imaging observations from the HOBYS key programme at wavelengths of 160, 250, 350, and 500 μm to construct dust temperature and column density maps. Using probability distribution functions (PDFs) of the column density determined for the whole complex and for four distinct sub-regions (distinguished on the basis of differences in the column density, temperature, and radiation field), we characterize the density structure of the complex. We investigate the spatial structure using the Δ-variance, which probes the relative amount of structure on different size scales and traces possible energy injection mechanisms into the molecular cloud.
Results: The Δ-variance analysis suggests that the significant scales of a few parsec that were found are caused by energy injection due to expanding HII regions, which are numerous, and by the lengths of filaments seen everywhere in the complex. The column density PDFs have a lognormal shape at low densities and a clearly defined power law at high densities for all sub-regions whose slope is linked to the exponent α of an equivalent spherical density distribution. In particular with α = 2.37, the central sub-region is largly dominated by gravity, caused by individual collapsing dense cores and global collapse of a larger region. The collapse is faster than free-fall (which would lead only to α = 2) and thus requires a more dynamic scenario (external compression, flows). The column density PDFs suggest that the different sub-regions are at different evolutionary stages, especially the central sub-region, which seems to be in a more evolved stage
Variants of OTOF and PJVK Genes in Chinese Patients with Auditory Neuropathy Spectrum Disorder
BACKGROUND: Mutations in OTOF and PJVK genes cause DFNB9 and DFNB59 types of hearing loss, respectively. The patients carrying pathogenic mutations in either of these genes may show the typical phenotype of auditory neuropathy spectrum disorder (ANSD). The aim of the present study was to identify OTOF and PJVK mutations in sporadic ANSD patients. METHODS AND FINDINGS: A total of 76 unrelated Chinese non-syndromic ANSD patients were sequenced on the gene OTOF and PJVK exon by exon. Variants were valued in 105 controls with normal hearing to verify the carrying rate. We identified one pathogenic mutation (c.1194T>A) and three novel, possibly pathogenic, variants (c.3570+2T>C, c.4023+1 G>A, and c.1102G>A) in the OTOF gene, and one novel, possibly pathogenic, variant (c.548G>A) in PJVK. Moreover, we found three novel missense mutations within the exons of OTOF. CONCLUSIONS: As we identified 4 and 1 possible pathogenic variants of the OTOF gene and the PJVK gene, respectively, we believe that screening in these genes are important in sporadic ANSD patients. The pathogenicity of these novel mutations needs further study because of their single heterozygous nature. Knowledge on the mutation spectra of these genes in Chinese would be beneficial in understanding the genetic character of this worldwide disease
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