878 research outputs found
Gap opening in graphene by shear strain
We exploit the concept of strain-induced band structure engineering in
graphene through the calculation of its electronic properties under uniaxial,
shear, and combined uniaxial-shear deformations. We show that by combining
shear deformations to uniaxial strains it is possible modulate the graphene
energy gap value from zero up to eV. Interestingly enough, the use of a
shear component allows for a gap opening at moderate absolute deformation,
safely smaller than the graphene failure strain.Comment: to appear on PRB - Rapid Communicatio
Spacelike hypersurfaces in standard static spacetimes
In this work we study spacelike hypersurfaces immersed in spatially open
standard static spacetimes with complete spacelike slices. Under appropriate
lower bounds on the Ricci curvature of the spacetime in directions tangent to
the slices, we prove that every complete CMC hypersurface having either bounded
hyperbolic angle or bounded height is maximal. Our conclusions follow from
general mean curvature estimates for spacelike hypersurfaces. In case where the
spacetime is a Lorentzian product with spatial factor of nonnegative Ricci
curvature and sectional curvatures bounded below, we also show that a complete
maximal hypersurface not intersecting a spacelike slice is itself a slice. This
result is obtained from a gradient estimate for parametric maximal
hypersurfaces.Comment: 50 page
SWIM: A computational tool to unveiling crucial nodes in complex biological networks
SWItchMiner (SWIM) is a wizard-like software implementation of a procedure, previously described, able to extract information contained in complex networks. Specifically, SWIM allows unearthing the existence of a new class of hubs, called "fight-club hubs", characterized by a marked negative correlation with their first nearest neighbors. Among them, a special subset of genes, called "switch genes", appears to be characterized by an unusual pattern of intra- and inter-module connections that confers them a crucial topological role, interestingly mirrored by the evidence of their clinic-biological relevance. Here, we applied SWIM to a large panel of cancer datasets from The Cancer Genome Atlas, in order to highlight switch genes that could be critically associated with the drastic changes in the physiological state of cells or tissues induced by the cancer development. We discovered that switch genes are found in all cancers we studied and they encompass protein coding genes and non-coding RNAs, recovering many known key cancer players but also many new potential biomarkers not yet characterized in cancer context. Furthermore, SWIM is amenable to detect switch genes in different organisms and cell conditions, with the potential to uncover important players in biologically relevant scenarios, including but not limited to human cancer
Remarks on mean curvature flow solitons in warped products
We study some properties of mean curvature flow solitons in general Riemannian manifolds and in warped products, with emphasis on constant curvature and Schwarzschild type spaces. We focus on splitting and rigidity results under various geometric conditions, ranging from the stability of the soliton to the fact that the image of its Gauss map be contained in suitable regions of the sphere. We also investigate the case of entire graphs
Mechanical characterization and modelling of Ultra High Performance Fiber Reinforced Concrete
In the last two decades the use of Ultra High Performance Fiber Reinforced Concrete (UHPFRC) for the construction of structural and non-structural elements has increased, but there is still a strong need to establish a complete method for its mechanical characterization, especially of its tensile behavior. In this paper, a mechanical investigation carried out on four UHPFRC specimens with a fiber volume fraction of 3.3% is presented. The fiber content resulted to be sufficient to cause strain hardening behavior, characterized by a multicracking phase. The tensile constitutive law provided by Model Code 2010 for the inverse analysis from bending tests is hereby discussed. In particular, the size of the mul-ticrack diffusion zone is investigated with vision-based measurement tools and used as a characteristic length
A splitting theorem for capillary graphs under Ricci lower bounds
In this paper, we study capillary graphs defined on a domain of a
complete Riemannian manifold , where a graph is said to be capillary if it
has constant mean curvature and locally constant Dirichlet and Neumann
conditions on . Our main result is a splitting theorem both
for and for the graph function on a class of manifolds with
nonnegative Ricci curvature. As a corollary, we classify capillary graphs over
domains that are globally Lipschitz epigraphs or slabs in a product space , where has slow volume growth and non-negative Ricci
curvature, including the case . A technical core
of the paper is a new gradient estimate for positive CMC graphs on manifolds
with Ricci lower bounds.Comment: 42 pages. Bibliography updated. Accepted on J. Funct. Ana
Remarks on mean curvature flow solitons in warped products
We study some properties of mean curvature flow solitons in general
Riemannian manifolds and in warped products, with emphasis on constant
curvature and Schwarzschild type spaces. We focus on splitting and rigidity
results under various geometric conditions, ranging from the stability of the
soliton to the fact that the image of its Gauss map be contained in suitable
regions of the sphere. We also investigate the case of entire graphs.Comment: 36 pages. This paper differs from the published one since the proof
of Theorem 3.4 (Thm. C in the Introduction) was rewritten. Package
axessibility added to make the paper available to visually impaired people.
Last version: some further detail added in the proof of Theorem 3.
On minimal graphs of sublinear growth over manifolds with non-negative Ricci curvature
We prove that entire solutions of the minimal hypersurface equation on a complete
manifold with , whose negative part grows like
( the distance from a fixed origin), are constant.
This extends the Bernstein Theorem for entire positive minimal graphs
established in recent years. The proof depends on a new technique to get
gradient bounds by means of integral estimates, which does not require any
further geometric assumption on .Comment: 19 pages. Comments are welcome
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