1,094 research outputs found
Are ecophysiological adaptive traits decoupled from leaf economics traits in wetlands?
Environmental Biolog
Assembly of the Inner Perivitelline Layer, a Homo log of the Mammalian Zona Pellucida: An Immunohistochemical and Ultrastructural Study
The avian inner perivitelline layer (IPVL), a homologous structure to the mammalian zona pellucida, is deposited between the granulosa cells and the oocyte cell membrane during folliculogenesis. The glycoprotein meshwork of the IPVL forms a 3-dimensional matrix and possesses important functions in the fertilization process: it contributes to the binding of avian spermatozoa to the oocyte and induces acrosomal exocytosis. In contrast to the zona pellucida of mammals, the IPVL does not prevent the physiological polyspermy found in birds. Previous studies have shown that in the Japanese quail (Cotumix japonica) at least 5 glycoproteins are constituents of the IPVL (ZP1, ZP2, ZP3, ZP4, and ZPD). In this study, we investigated the spatiotennporal assembly pattern of the IPVL during folliculogenesis using immunohistochemical and ultrastructural methods. The obtained results clearly show that these glycoproteins are incorporated into the IPVL at distinct points during follicular development, supporting the hypothesis that ZP2 and ZP4 form a type of prematrix into which ZP1, ZP3, and ZPD are integrated at a later stage of development. Copyright (C) 2011 S. Karger AG, Base
Decoherence and entanglement degradation of a qubit-qutrit system in non-inertial frames
We study the effect of decoherence on a qubit-qutrit system under the
influence of global, local and multilocal decoherence in non-inertial frames.
We show that the entanglement sudden death can be avoided in non-inertial
frames in the presence of amplitude damping, depolarizing and phase damping
channels. However, degradation of entanglement is seen due to Unruh effect. It
is shown that for lower level of decoherence, the depolarizing channel degrades
the entanglement more heavily as compared to the amplitude damping and phase
damping channels. However, for higher values of decoherence parameters,
amplitude damping channel heavily degrades the entanglement of the hybrid
system. Further more, no ESD is seen for any value of Rob's acceleration.Comment: 16 pages, 5 .eps figures, 1 table; Quantum Information Processing,
published online, 5 July, 201
Isospin influences on particle emission and critical phenomenon in nuclear dissociation
Features of particle emission and critical point behavior are investigated as
functions of the isospin of disassembling sources and temperature at a moderate
freeze-out density for medium-size Xe isotopes in the framework of isospin
dependent lattice gas model. Multiplicities of emitted light particles,
isotopic and isobaric ratios of light particles show the strong dependence on
the isospin of the dissociation source, but double ratios of light isotope
pairs and the critical temperature determined by the extreme values of some
critical observables are insensitive to the isospin of the systems. Values of
the power law parameter of cluster mass distribution, mean multiplicity of
intermediate mass fragments (), information entropy () and Campi's
second moment () also show a minor dependence on the isospin of Xe
isotopes at the critical point. In addition, the slopes of the average
multiplicites of the neutrons (), protons (), charged particles
(), and IMFs (), slopes of the largest fragment mass number
(), and the excitation energy per nucleon of the disassembling source
() to temperature are investigated as well as variances of the
distributions of , , , , and . It
is found that they can be taken as additional judgements to the critical
phenomena.Comment: 9 Pages, 8 figure
Nebular spectra and abundance tomography of the Type Ia supernova SN 2011fe: a normal SN Ia with a stable Fe core
A series of optical and one near-infrared nebular spectra covering the first year of the Type Ia supernova SN 2011fe are presented and modelled. The density profile that proved best for the early optical/ultraviolet spectra, ‘?-11fe’, was extended to lower velocities to include the regions that emit at nebular epochs. Model ?-11fe is intermediate between the fast deflagration model W7 and a low-energy delayed-detonation. Good fits to the nebular spectra are obtained if the innermost ejecta are dominated by neutron-rich, stable Fe-group species, which contribute to cooling but not to heating. The correct thermal balance can thus be reached for the strongest [Fe ii] and [Fe iii] lines to be reproduced with the observed ratio. The 56Ni mass thus obtained is ?0.47 ± 0.05?M?. The bulk of 56Ni has an outermost velocity of ?8500 km s?1. The mass of stable iron is ?0.23 ± 0.03?M?. Stable Ni has low abundance, ?10?2?M?. This is sufficient to reproduce an observed emission line near 7400 Å. A sub-Chandrasekhar explosion model with mass 1.02?M? and no central stable Fe does not reproduce the observed line ratios. A mock model where neutron-rich Fe-group species are located above 56Ni following recent suggestions is also shown to yield spectra that are less compatible with the observations. The densities and abundances in the inner layers obtained from the nebular analysis, combined with those of the outer layers previously obtained, are used to compute a synthetic bolometric light curve, which compares favourably with the light curve of SN 2011fe
Formation of Small-Scale Condensations in the Molecular Clouds via Thermal Instability
A systematic study of the linear thermal instability of a self-gravitating
magnetic molecular cloud is carried out for the case when the unperturbed
background is subject to local expansion or contraction. We consider the
ambipolar diffusion, or ion-neutral friction on the perturbed states. In this
way, we obtain a non-dimensional characteristic equation that reduces to the
prior characteristic equation in the non-gravitating stationary background. By
parametric manipulation of this characteristic equation, we conclude that there
are, not only oblate condensation forming solutions, but also prolate solutions
according to local expansion or contraction of the background. We obtain the
conditions for existence of the Field lengths that thermal instability in the
molecular clouds can occur. If these conditions establish, small-scale
condensations in the form of spherical, oblate, or prolate may be produced via
thermal instability.Comment: 16 page, accepted by Ap&S
Effects of momentum conservation on the analysis of anisotropic flow
We present a general method for taking into account correlations due to
momentum conservation in the analysis of anisotropic flow, either by using the
two-particle correlation method or the standard flow vector method. In the
latter, the correlation between the particle and the flow vector is either
corrected through a redefinition (shift) of the flow vector, or subtracted
explicitly from the observed flow coefficient. In addition, momentum
conservation contributes to the reaction plane resolution. Momentum
conservation mostly affects the first harmonic in azimuthal distributions,
i.e., directed flow. It also modifies higher harmonics, for instance elliptic
flow, when they are measured with respect to a first harmonic event plane such
as one determined with the standard transverse momentum method. Our method is
illustrated by application to NA49 data on pion directed flow.Comment: RevTeX 4, 10 pages, 1 eps figure. Version accepted for publication in
Phys Rev
Leading trait dimensions in flood-tolerant plants
Background and AimsWhile trait-based approaches have provided critical insights in general plant functioning, we lack a comprehensive quantitative view on plant strategies in flooded conditions. Plants adapted to flooded conditions have specific traits (e.g., root porosity, low root/shoot ratio, and shoot elongation) to cope with the environmental stressors including anoxic sediments, and the subsequent presence of phytotoxic compounds. In flooded habitats, plants also respond to potential nutrient and light limitations, e.g., through the expression of leaf economics traits and size-related, respectively. However, we don’t know whether and how these trait dimensions are connected.MethodsBased on a trait dataset compiled on 131 plant species from 141 studies in flooded habitats, we quantitatively analysed how flooding-induced traits are positioned in relation to the other two dominant trait dimensions; leaf economics and size-related traits. We evaluated how these key trait components are expressed along wetness gradients, across habitat types and among plant life forms.Key ResultsWe found that flooding-induced traits constitute a trait dimension independent from leaf economics traits and size-related traits, indicating that there is no generic trade-off associated to flooding adaptations. Moreover, individual flooding-induced traits themselves are to a large extent decoupled from each other. These results suggest that adaptation to stressful environments, such as flooding, can be stressor-specific without generic adverse effects on plant functioning (e.g., causing trade-offs on leaf economics traits).ConclusionsThe trait expressions across multiple dimensions promote plant adaptations and co-existence across multi-faceted flooded environments. The decoupled trait dimensions, as related to different environmental drivers, also explain why ecosystem functioning (including e.g. methane emissions) are species- and habitat-specific. Thus, our results provide a backbone for applying trait-based approaches in wetland ecology by considering flooding-induced traits as an independent trait dimension.Environmental Biolog
Hamiltonian theory of gaps, masses and polarization in quantum Hall states: full disclosure
I furnish details of the hamiltonian theory of the FQHE developed with Murthy
for the infrared, which I subsequently extended to all distances and apply it
to Jain fractions \nu = p/(2ps + 1). The explicit operator description in terms
of the CF allows one to answer quantitative and qualitative issues, some of
which cannot even be posed otherwise. I compute activation gaps for several
potentials, exhibit their particle hole symmetry, the profiles of charge
density in states with a quasiparticles or hole, (all in closed form) and
compare to results from trial wavefunctions and exact diagonalization. The
Hartree-Fock approximation is used since much of the nonperturbative physics is
built in at tree level. I compare the gaps to experiment and comment on the
rough equality of normalized masses near half and quarter filling. I compute
the critical fields at which the Hall system will jump from one quantized value
of polarization to another, and the polarization and relaxation rates for half
filling as a function of temperature and propose a Korringa like law. After
providing some plausibility arguments, I explore the possibility of describing
several magnetic phenomena in dirty systems with an effective potential, by
extracting a free parameter describing the potential from one data point and
then using it to predict all the others from that sample. This works to the
accuracy typical of this theory (10 -20 percent). I explain why the CF behaves
like free particle in some magnetic experiments when it is not, what exactly
the CF is made of, what one means by its dipole moment, and how the comparison
of theory to experiment must be modified to fit the peculiarities of the
quantized Hall problem
Global patterns of the leaf economics spectrum in wetlands
The leaf economics spectrum (LES) describes consistent correlations among a variety of leaf traits that reflect a gradient from conservative to acquisitive plant strategies. So far, whether the LES holds in wetland plants at a global scale has been unclear. Using data on 365 wetland species from 151 studies, we find that wetland plants in general show a shift within trait space along the same common slope as observed in non-wetland plants, with lower leaf mass per area, higher leaf nitrogen and phosphorus, faster photosynthetic rates, and shorter leaf life span compared to non-wetland plants. We conclude that wetland plants tend to cluster at the acquisitive end of the LES. The presented global quantifications of the LES in wetland plants enhance our understanding of wetland plant strategies in terms of resources acquisition and allocation, and provide a stepping-stone to developing trait-based approaches for wetland ecology.Environmental Biolog
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