18,192 research outputs found
An annotated checklist of the bryophytes of Taita Hills region, Kenya
Based on previous literature and our own collections, we list 288 bryophyte species (145 liverworts, 143 mosses) from the Taita Hills region (including Mt. Kasigau and Maktau Hill) in SE Kenya. New records for Kenya include the liverworts Archilejeunea elobulata Steph., Bazzania nitida (F. Weber) Grolle, Cololejeunea grossepapillosa (Horik.) N. Kitag., Diplasiolejeunea kraussiana (Lindenb.) Steph., D. villaumei Steph., Lejeunea amaniensis E.W. Jones, L. cyathearum E.W. Jones, Lopholejeunea laciniata E.W. Jones, Metzgeria crassipilis (Lindb.) A. Evans, M. nudifrons Steph., Plagiochila boryana (F. Weber) Nees, and P. moenkemeyeri Steph., and the mosses Leucophanes hildebrandtii Müll. Hal. and Neckeromnion lepineanum (Mont.) S. Olsson, Enroth, Huttunen & D. Quandt. A further 22 liverworts and 13 mosses previously known from other parts of Kenya are reported for the first time from the Taita Hills region.Peer reviewe
Finite temperature calculations for the bulk properties of strange star using a many-body approach
We have considered a hot strange star matter, just after the collapse of a
supernova, as a composition of strange, up and down quarks to calculate the
bulk properties of this system at finite temperature with the density dependent
bag constant. To parameterize the density dependent bag constant, we use our
results for the lowest order constrained variational (LOCV) calculations of
asymmetric nuclear matter. Our calculations for the structure properties of the
strange star at different temperatures indicate that its maximum mass decreases
by increasing the temperature. We have also compared our results with those of
a fixed value of the bag constant. It can be seen that the density dependent
bag constant leads to higher values of the maximum mass and radius for the
strange star.Comment: 21 pages, 2 tables, 12 figures Astrophys. (2011) accepte
Small RNA analysis in Sindbis virus infected human HEK293 cells
In contrast to the defence mechanism of RNA interference (RNAi) in plants and invertebrates, its role in the innate response to virus infection of mammals is a matter of debate. Since RNAi has a well-established role in controlling infection of the alphavirus Sindbis virus (SINV) in insects, we have used this virus to investigate the role of RNAi in SINV infection of human cells
Analysis of White Dwarfs with Strange-Matter Cores
We summarize masses and radii for a number of white dwarfs as deduced from a
combination of proper motion studies, Hipparcos parallax distances, effective
temperatures, and binary or spectroscopic masses. A puzzling feature of these
data is that some stars appear to have radii which are significantly smaller
than that expected for a standard electron-degenerate white-dwarf equations of
state. We construct a projection of white-dwarf radii for fixed effective mass
and conclude that there is at least marginal evidence for bimodality in the
radius distribution forwhite dwarfs. We argue that if such compact white dwarfs
exist it is unlikely that they contain an iron core. We propose an alternative
of strange-quark matter within the white-dwarf core. We also discuss the impact
of the so-called color-flavor locked (CFL) state in strange-matter core
associated with color superconductivity. We show that the data exhibit several
features consistent with the expected mass-radius relation of strange dwarfs.
We identify eight nearby white dwarfs which are possible candidates for strange
matter cores and suggest observational tests of this hypothesis.Comment: 11 pages, 6 figures, accepted for publication in J. Phys. G: Nucl.
Part. Phy
INDICATION OF META-ANTHRACITE BY MAGNETOTELLURICS IN THE KŐSZEG-RECHNITZ PENNINIC WINDOW : A TEST AREA
One of the Penninic Nappes is the Kőszeg-Rechnitz (K-R) tectonic window at the Eastern end of the Eastern Alps. It has a complicated metamorphic history from the Jurassic time. The organic material of the Penninic Ocean was transformed to electrically conductive meta-anthracite. Its amount in the chalcophyllite is estimated by geochemists to 0.2 per cent.
Taking this conducting structure as a test area pilot deep magnetotelluric (MT) soundings have been carried out and we determined
- the structure of the conductivity anomaly due to 0.2 per cent meta anthracite in the K-R window and its surroundings
- the different kinds of MT distortions as lateral (side) effect of the conductor appearing in the crust and mantle
- the most probable depth of the conductive asthenosphere at the border of the Pannonian Basin (having extreme shallow asthenosphere). The obtained ~140 km depth is in correlation with value of the asthenospheric map based mainly on seismic data
Giant phonon anomalies and central peak due to charge density wave formation in YBaCuO
The electron-phonon interaction is a major factor influencing the competition
between collective instabilities in correlated-electron materials, but its role
in driving high-temperature superconductivity in the cuprates remains poorly
understood. We have used high-resolution inelastic x-ray scattering to monitor
low-energy phonons in YBaCuO (superconducting
K), which is close to a charge density wave (CDW) instability. Phonons in a
narrow range of momentum space around the CDW ordering vector exhibit extremely
large superconductivity-induced lineshape renormalizations. These results imply
that the electron-phonon interaction has sufficient strength to generate
various anomalies in electronic spectra, but does not contribute significantly
to Cooper pairing. In addition, a quasi-elastic "central peak" due to CDW
nanodomains is observed in a wide temperature range above and below ,
suggesting that the gradual onset of a spatially inhomogeneous CDW domain state
with decreasing temperature is a generic feature of the underdoped cuprates
Surface structure of Quark stars with magnetic fields
We investigate the impact of magnetic fields on the electron distribution in
the electrosphere of quark stars. For moderately strong magnetic fields G, quantization effects are generally weak due to the large number
density of electrons at surface, but can nevertheless affect the spectral
features of quark stars. We outline the main observational characteristics of
quark stars as determined by their surface emission, and briefly discuss their
formation in explosive events termed Quark-Novae, which may be connected to the
-process.Comment: 9 pages, 3 figures. Contribution to the proceedings of the IXth
Workshop on High Energy Physics Phenomenology (WHEPP-9), Bhubaneswar, India,
3-14 Jan. 200
Thermodynamic Properties of Holographic Multiquark and the Multiquark Star
We study thermodynamic properties of the multiquark nuclear matter. The
dependence of the equation of state on the colour charges is explored both
analytically and numerically in the limits where the baryon density is small
and large at fixed temperature between the gluon deconfinement and chiral
symmetry restoration. The gravitational stability of the hypothetical
multiquark stars are discussed using the Tolman-Oppenheimer-Volkoff equation.
Since the equations of state of the multiquarks can be well approximated by
different power laws for small and large density, the content of the multiquark
stars has the core and crust structure. We found that most of the mass of the
star comes from the crust region where the density is relatively small. The
mass limit of the multiquark star is determined as well as its relation to the
star radius. For typical energy density scale of ,
the converging mass and radius of the hypothetical multiquark star in the limit
of large central density are approximately solar mass and 15-27 km.
The adiabatic index and sound speed distributions of the multiquark matter in
the star are also calculated and discussed. The sound speed never exceeds the
speed of light and the multiquark matters are thus compressible even at high
density and pressure.Comment: 27 pages, 17 figures, 1 table, JHEP versio
Bilayer manganites: polarons in the midst of a metallic breakdown
The exact nature of the low temperature electronic phase of the manganite
materials family, and hence the origin of their colossal magnetoresistant (CMR)
effect, is still under heavy debate. By combining new photoemission and
tunneling data, we show that in La{2-2x}Sr{1+2x}Mn2O7 the polaronic degrees of
freedom win out across the CMR region of the phase diagram. This means that the
generic ground state is that of a system in which strong electron-lattice
interactions result in vanishing coherent quasi-particle spectral weight at the
Fermi level for all locations in k-space. The incoherence of the charge
carriers offers a unifying explanation for the anomalous charge-carrier
dynamics seen in transport, optics and electron spectroscopic data. The
stacking number N is the key factor for true metallic behavior, as an
intergrowth-driven breakdown of the polaronic domination to give a metal
possessing a traditional Fermi surface is seen in the bilayer system.Comment: 7 pages, 2 figures, includes supplementary informatio
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