192 research outputs found
The principle of sustainability (durability) in private forests in Serbia
Укупна површина под шумом у Републици Србији износи 2.252.400 ха или 29,1% (НИШ, 2009)...Total forest area in the Republic of Serbia amounts to 2.252.400 ha or 29,1% (NFI, 2009)..
Even Galois Representations and the Fontaine--Mazur conjecture II
We prove, under mild hypotheses, that there are no irreducible
two-dimensional_even_ Galois representations of \Gal(\Qbar/\Q) which are de
Rham with distinct Hodge--Tate weights. This removes the "ordinary" hypothesis
required in previous work of the author. We construct examples of irreducible
two-dimensional residual representations that have no characteristic zero
geometric (= de Rham) deformations.Comment: Updated to take into account suggestions of the referee; the main
theorems remain unchange
The orbifold cohomology of moduli of genus 3 curves
In this work we study the additive orbifold cohomology of the moduli stack of
smooth genus g curves. We show that this problem reduces to investigating the
rational cohomology of moduli spaces of cyclic covers of curves where the genus
of the covering curve is g. Then we work out the case of genus g=3.
Furthermore, we determine the part of the orbifold cohomology of the
Deligne-Mumford compactification of the moduli space of genus 3 curves that
comes from the Zariski closure of the inertia stack of M_3.Comment: 29 pages, 2 figures. Minor changes, to appear in Manuscripta Mat
Bulk-boundary correspondence in three dimensional topological insulators
We discuss the relation between bulk topological invariants and the spectrum
of surface states in three dimensional non-interacting topological insulators.
By studying particular models, and considering general boundary conditions for
the electron wavefunction on the crystal surface, we demonstrate that using
experimental techniques that probe surface states, only strong topological and
trivial insulating phases can be distinguished; the latter state being
equivalent to a weak topological insulator. In a strong topological insulator,
only the {\it parity} of the number of surface states, but not the number
itself, is robust against time-reversal invariant boundary perturbations. Our
results suggest a \z definition of the bulk-boundary correspondence,
compatible with the \z classification of topological insulators.Comment: TeXLive (Unix), revtex4-1, 7 pages, 3 figure
Integrated Analysis of Dysregulated ncRNA and mRNA Expression Profiles in Humans Exposed to Carbon Nanotubes
Background As the application of carbon nanotubes (CNT) in consumer products continues to rise, studies have expanded to determine the associated risks of exposure on human and environmental health. In particular, several lines of evidence indicate that exposure to multi-walled carbon nanotubes (MWCNT) could pose a carcinogenic risk similar to asbestos fibers. However, to date the potential markers of MWCNT exposure are not yet explored in humans.
Methods In the present study, global mRNA and ncRNA expression profiles in the blood of exposed workers, having direct contact with MWCNT aerosol for at least 6 months (n = 8), were compared with expression profiles of non-exposed (n = 7) workers (e.g., professional and/or technical staff) from the same manufacturing facility.
Results Significant changes in the ncRNA and mRNA expression profiles were observed between exposed and non-exposed worker groups. An integrative analysis of ncRNA-mRNA correlations was performed to identify target genes, functional relationships, and regulatory networks in MWCNT-exposed workers. The coordinated changes in ncRNA and mRNA expression profiles revealed a set of miRNAs and their target genes with roles in cell cycle regulation/progression/control, apoptosis and proliferation. Further, the identified pathways and signaling networks also revealed MWCNT potential to trigger pulmonary and cardiovascular effects as well as carcinogenic outcomes in humans, similar to those previously described in rodents exposed to MWCNTs.
Conclusion This study is the first to investigate aberrant changes in mRNA and ncRNA expression profiles in the blood of humans exposed to MWCNT. The significant changes in several miRNAs and mRNAs expression as well as their regulatory networks are important for getting molecular insights into the MWCNT-induced toxicity and pathogenesis in humans. Further large-scale prospective studies are necessary to validate the potential applicability of such changes in mRNAs and miRNAs as prognostic markers of MWCNT exposures in humans
First-principles envelope-function theory for lattice-matched semiconductor heterostructures
In this paper a multi-band envelope-function Hamiltonian for lattice-matched
semiconductor heterostructures is derived from first-principles norm-conserving
pseudopotentials. The theory is applicable to isovalent or heterovalent
heterostructures with macroscopically neutral interfaces and no spontaneous
bulk polarization. The key assumption -- proved in earlier numerical studies --
is that the heterostructure can be treated as a weak perturbation with respect
to some periodic reference crystal, with the nonlinear response small in
comparison to the linear response. Quadratic response theory is then used in
conjunction with k.p perturbation theory to develop a multi-band effective-mass
Hamiltonian (for slowly varying envelope functions) in which all interface
band-mixing effects are determined by the linear response. To within terms of
the same order as the position dependence of the effective mass, the quadratic
response contributes only a bulk band offset term and an interface dipole term,
both of which are diagonal in the effective-mass Hamiltonian. Long-range
multipole Coulomb fields arise in quantum wires or dots, but have no
qualitative effect in two-dimensional systems beyond a dipole contribution to
the band offsets.Comment: 25 pages, no figures, RevTeX4; v3: final published versio
Actions infinit\'esimales dans la correspondance de Langlands locale p-adique
Let V be a two-dimensional absolutely irreducible p-adic Galois
representation and let Pi be the p-adic Banach space representation associated
to V via Colmez's p-adic Langlands correspondence. We establish a link between
the infinitesimal action of GL_2(Q_p) on the locally analytic vectors of Pi,
the differential equation associated to V via the theory of Fontaine and
Berger, and the Sen polynomial of V. This answers a question of Harris and
gives a new proof of a theorem of Colmez: Pi has nonzero locally algebraic
vectors if and only if V is potentially semi-stable with distinct Hodge-Tate
weights.Comment: Completely revised version, to appear in Math. Annale
The classification of irreducible admissible mod p representations of a p-adic GL_n
Let F be a finite extension of Q_p. Using the mod p Satake transform, we
define what it means for an irreducible admissible smooth representation of an
F-split p-adic reductive group over \bar F_p to be supersingular. We then give
the classification of irreducible admissible smooth GL_n(F)-representations
over \bar F_p in terms of supersingular representations. As a consequence we
deduce that supersingular is the same as supercuspidal. These results
generalise the work of Barthel-Livne for n = 2. For general split reductive
groups we obtain similar results under stronger hypotheses.Comment: 55 pages, to appear in Inventiones Mathematica
Reflection of light and heavy holes from a linear potential barrier
In this paper we study reflection of holes in direct-band semiconductors from
the linear potential barrier. It is shown that light-heavy hole transformation
matrix is universal. It depends only on a dimensionless product of the light
hole longitudinal momentum and the characteristic length determined by the
slope of the potential and doesn't depend on the ratio of light and heavy hole
masses, provided this ratio is small. It is shown that the transformation
coefficient goes to zero both in the limit of small and large longitudinal
momenta, however the phase of a reflected hole is different in these limits. An
approximate analytical expression for the light-heavy hole transformation
coefficient is found.Comment: 6 pages, 2 figure
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