871 research outputs found
Growth, immunity and ammonia excretion of albino and normal Apostichopus japonicus (Selenka) feeding with various experimental diets
An experiment was conducted to evaluate the effects of six experimental diets on growth performance, ammonia excretion and immunity of albino and normal Apostichopus japonicus. A factorial design was used, the factors being type of diets (six levels) and colour of A. japonicus (two levels). A total of 30 randomly selected albino A. japonicus were housed in each (60 × 50 × 30 cm3) of 18 blue plastic aquaria to form six groups in triplicate, and the same set-up
was used for the normal A. japonicus. Each group of animals was fed with one of the six experimental diets. Apparent dry matter digestibility (ADMD) and apparent crude protein digestibility (ACPD) were analysed using acid-insoluble
ash (AIA) content method. At the end of the experiment, all
A. japonicus were harvested and weighed to calculate growth parameters. After weighing, six individuals from each aquarium were randomly sampled for immune indices.
Results indicated that all growth parameters of A. japonicus increased with decreasing nutrient content in their diets (p < .01), whereas an opposite result was observed in
case of the ammonia-nitrogen production by A. japonicus. Normal A. japonicus grew better (p < .01) and produced lower (p < .01) quantity of ammonia nitrogen compared to the albino A. japonicus. Immunity particularly superoxide dismutase and lysozyme activities was higher (p < .05) in normal compared to albino A. japonicus. Considering
all measured variables, D1 (diet containing crude protein, crude lipid, carbohydrate and crude ash 51.8, 8.7, 231.3, 708.2 g/kg, respectively) was the best diet among all
experimental diets. More research is still needed to optimize nutrients in the diet of A. japonicus, as this study does not provide information about critical threshold level of nutrients in diets. Until then, diet D1 can be recommended for A. japonicus aquaculture
Syzygies in equivariant cohomology for non-abelian Lie groups
We extend the work of Allday-Franz-Puppe on syzygies in equivariant
cohomology from tori to arbitrary compact connected Lie groups G. In
particular, we show that for a compact orientable G-manifold X the analogue of
the Chang-Skjelbred sequence is exact if and only if the equivariant cohomology
of X is reflexive, if and only if the equivariant Poincare pairing for X is
perfect. Along the way we establish that the equivariant cohomology modules
arising from the orbit filtration of X are Cohen-Macaulay. We allow singular
spaces and introduce a Cartan model for their equivariant cohomology. We also
develop a criterion for the finiteness of the number of infinitesimal orbit
types of a G-manifold.Comment: 28 pages; minor change
A Self-Consistent First-Principles Technique Having Linear Scaling
An algorithm for first-principles electronic structure calculations having a
computational cost which scales linearly with the system size is presented. Our
method exploits the real-space localization of the density matrix, and in this
respect it is related to the technique of Li, Nunes and Vanderbilt. The density
matrix is expressed in terms of localized support functions, and a matrix of
variational parameters, L, having a finite spatial range. The total energy is
minimized with respect to both the support functions and the elements of the L
matrix. The method is variational, and becomes exact as the ranges of the
support functions and the L matrix are increased. We have tested the method on
crystalline silicon systems containing up to 216 atoms, and we discuss some of
these results.Comment: 12 pages, REVTeX, 2 figure
Edge reconstruction in the fractional quantum Hall regime
The interplay of electron-electron interaction and confining potential can
lead to the reconstruction of fractional quantum Hall edges. We have performed
exact diagonalization studies on microscopic models of fractional quantum Hall
liquids, in finite size systems with disk geometry, and found numerical
evidence of edge reconstruction under rather general conditions. In the present
work we have taken into account effects like layer thickness and Landau level
mixing, which are found to be of quantitative importance in edge physics. Due
to edge reconstruction, additional nonchiral edge modes arise for both
incompressible and compressible states. These additional modes couple to
electromagnetic fields and thus can be detected in microwave conductivity
measurements. They are also expected to affect the exponent of electron Green's
function, which has been measured in tunneling experiments. We have studied in
this work the electric dipole spectral function that is directly related to the
microwave conductivity measurement. Our results are consistent with the
enhanced microwave conductivity observed in experiments performed on samples
with an array of antidots at low temperatures, and its suppression at higher
temperatures. We also discuss the effects of the edge reconstruction on the
single electron spectral function at the edge.Comment: 19 pages, 12 figure
Anomalous Superconducting Properties and Field Induced Magnetism in CeCoIn5
In the heavy fermion superconductor CeCoIn5 (Tc=2.3K) the critical field is
large, anisotropic and displays hysteresis. The magnitude of the critical-field
anisotropy in the a-c plane can be as large as 70 kOe and depends on
orientation. Critical field measurements in the (110) plane suggest 2D
superconductivity, whereas conventional effective mass anisotropy is observed
in the (100) plane. Two distinct field-induced magnetic phases are observed: Ha
appears deep in the superconducting phase, while Hb intersects Hc2 at T=1.4 K
and extends well above Tc. These observations suggest the possible realization
of a direct transition from ferromagnetism to Fulde-Ferrel-Larkin-Ovchinnikov
superconductivity in CeCoIn5.Comment: 4 pages, 3 figure
Contribution of biomimetic collagen-ligand interaction to intrafibrillar mineralization
Contemporary models of intrafibrillar mineralization mechanisms are established using collagen fibrils as templates without considering the contribution from collagen-bound apatite nucleation inhibitors. However, collagen matrices destined for mineralization in vertebrates contain bound matrix proteins for intrafibrillar mineralization. Negatively charged, high\u2013molecular weight polycarboxylic acid is cross-linked to reconstituted collagen to create a model for examining the contribution of collagen-ligand interaction to intrafibrillar mineralization. Cryogenic electron microscopy and molecular dynamics simulation show that, after cross-linking to collagen, the bound polyelectrolyte caches prenucleation cluster singlets into chain-like aggregates along the fibrillar surface to increase the pool of mineralization precursors available for intrafibrillar mineralization. Higher-quality mineralized scaffolds with better biomechanical properties are achieved compared with mineralization of unmodified scaffolds in polyelectrolyte-stabilized mineralization solution. Collagen-ligand interaction provides insights on the genesis of heterogeneously mineralized tissues and the potential causes of ectopic calcification in nonmineralized body tissues
Competition between decay and dissociation of core-excited OCS studied by X-ray scattering
We show the first evidence of dissociation during resonant inelastic soft
X-ray scattering. Carbon and oxygen K-shell and sulfur L-shell resonant and
non-resonant X-ray emission spectra were measured using monochromatic
synchrotron radiation for excitation and ionization. After sulfur, L2,3 ->
{\pi}*, {\sigma}* excitation, atomic lines are observed in the emission spectra
as a consequence of competition between de-excitation and dissociation. In
contrast the carbon and oxygen spectra show weaker line shape variations and no
atomic lines. The spectra are compared to results from ab initio calculations
and the discussion of the dissociation paths is based on calculated potential
energy surfaces and atomic transition energies.Comment: 12 pages, 6 pictures, 2 tables,
http://link.aps.org/doi/10.1103/PhysRevA.59.428
Proximity induced metal/insulator transition in superlattices
The far-infrared dielectric response of superlattices (SL) composed of
superconducting YBaCuO (YBCO) and ferromagnetic La%
CaMnO (LCMO) has been investigated by ellipsometry. A drastic
decrease of the free carrier response is observed which involves an unusually
large length scale of d20 nm in YBCO and d10
nm in LCMO. A corresponding suppression of metallicity is not observed in SLs
where LCMO is replaced by the paramagnetic metal LaNiO. Our data suggest
that either a long range charge transfer from the YBCO to the LCMO layers or
alternatively a strong coupling of the charge carriers to the different and
competitive kind of magnetic correlations in the LCMO and YBCO layers are at
the heart of the observed metal/insulator transition. The low free carrier
response observed in the far-infrared dielectric response of the magnetic
superconductor RuSrGdCuO is possibly related to this effect
Specific Heat Study of the Magnetic Superconductor HoNi2B2C
The complex magnetic transitions and superconductivity of HoNi2B2C were
studied via the dependence of the heat capacity on temperature and in-plane
field angle. We provide an extended, comprehensive magnetic phase diagram for B
// [100] and B // [110] based on the thermodynamic measurements. Three magnetic
transitions and the superconducting transition were clearly observed. The 5.2 K
transition (T_{N}) shows a hysteresis with temperature, indicating the first
order nature of the transition at B=0 T. The 6 K transition (T_{M}), namely the
onset of the long-range ordering, displays a dramatic in-plane anisotropy:
T_{M} increases with increasing magnetic field for B // [100] while it
decreases with increasing field for B // [110]. The anomalous anisotropy in
T_{M} indicates that the transition is related to the a-axis spiral structure.
The 5.5 K transition (T^{*}) shows similar behavior to the 5.2 K transition,
i.e., a small in-plane anisotropy and scaling with Ising model. This last
transition is ascribed to the change from a^{*} dominant phase to c^{*}
dominant phase.Comment: 9 pages, 11 figure
Magnetic field - temperature phase diagram of quasi-two-dimensional organic superconductor lambda-(BETS)_2 GaCl_4 studied via thermal conductivity
The thermal conductivity kappa of the quasi-two-dimensional (Q2D) organic
superconductor lambda-(BETS)_2 GaCl_4 was studied in the magnetic field H
applied parallel to the Q2D plane. The phase diagram determined from this bulk
measurement shows notable dependence on the sample quality. In dirty samples
the upper critical field H_{c2} is consistent with the Pauli paramagnetic
limiting, and a sharp change is observed in kappa(H) at H_{c2 parallel}. In
contrast in clean samples H_{c2}(T) shows no saturation towards low
temperatures and the feature in kappa(H) is replaced by two slope changes
reminiscent of second-order transitions. The peculiarity was observed below ~
0.33T_c and disappeared on field inclination to the plane when the orbital
suppression of superconductivity became dominant. This behavior is consistent
with the formation of a superconducting state with spatially modulated order
parameter in clean samples.Comment: 10 pages, 8 figures, new figure (Fig.5) and references added, title
change
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