8,227 research outputs found
Axiomatic Digital Topology
The paper presents a new set of axioms of digital topology, which are easily
understandable for application developers. They define a class of locally
finite (LF) topological spaces. An important property of LF spaces satisfying
the axioms is that the neighborhood relation is antisymmetric and transitive.
Therefore any connected and non-trivial LF space is isomorphic to an abstract
cell complex. The paper demonstrates that in an n-dimensional digital space
only those of the (a, b)-adjacencies commonly used in computer imagery have
analogs among the LF spaces, in which a and b are different and one of the
adjacencies is the "maximal" one, corresponding to 3n\"i1 neighbors. Even these
(a, b)-adjacencies have important limitations and drawbacks. The most important
one is that they are applicable only to binary images. The way of easily using
LF spaces in computer imagery on standard orthogonal grids containing only
pixels or voxels and no cells of lower dimensions is suggested
Supersymmetric Higgs Bosons and Beyond
We consider supersymmetric models that include particles beyond the Minimal
Supersymmetric Standard Model (MSSM) with masses in the TeV range, and that
couple significantly to the MSSM Higgs sector. We perform a model-independent
analysis of the spectrum and couplings of the MSSM Higgs fields, based on an
effective theory of the MSSM degrees of freedom. The tree-level mass of the
lightest CP-even state can easily be above the LEP bound of 114 GeV, thus
allowing for a relatively light spectrum of superpartners, restricted only by
direct searches. The Higgs spectrum and couplings can be significantly modified
compared to the MSSM ones, often allowing for interesting new decay modes. We
also observe that the gluon fusion production cross section of the SM-like
Higgs can be enhanced with respect to both the Standard Model and the MSSM.Comment: References added. Mistake in Eq. 14 corrected, conclusions unchanged.
Typos corrected. Version accepted for publication in PRD. 50 pages, 29
figure
Radiative corrections to the Casimir force and effective field theories
Radiative corrections to the Casimir force between two parallel plates are
considered in both scalar field theory of one massless and one massive field
and in QED. Full calculations are contrasted with calculations based on
employing ``boundary-free'' effective field theories. The difference between
two previous results on QED radiative corrections to the Casimir force between
two parallel plates is clarified and the low-energy effective field theory for
the Casimir effect in QED is constructed.Comment: 17 pages, revte
A protocol for Agrobacterium-mediated transformation of Kalanchoë blossfeldiana with a flavonoid 3',5' hydroxylase (F3'5'H) gene
In the present investigation, explants from Kalanchoë blossfeldiana were used for gene transformation. The young leaves were inoculated with Agrobacterium tumefaciens LBA4404 strain with a binary vector plasmid pArtblue containing F3'5'H gene under control of CaMV35S promoter and nptII selectable marker gene. After inoculation, the explants were transferred to the co-cultivation medium. They were then transferred to the selection medium containing kanamycin and were sub-cultured every two weeks. Leaves of the putative transgenic shoots that survived in the selection medium were used in reverse transcription polymerase chain reaction (RT-PCR) analysis to detect gene expression. The RT-PCR analysis showed the presence of 550 bp F3'5'H amplification products and had an expression of F3'5'H gene. Plants with the introduced F3'5'H gene produced totally pale red flowers.Key words: Kalanchoë blossfeldiana, Agrobacterium-mediated transformation, young leaf, F3'5'H gene, reverse transcription-polymerase chain reaction (RT-PCR)
A second black hole candidate in a M31 globular cluster is identified with XMM-Newton
We use arguments developed in previous work to identify a second black hole
candidate associated with a M31 globular cluster, Bo 144, on the basis of X-ray
spectral and timing properties. The 2002 XMM-Newton observation of the
associated X-ray source (hereafter XBo 144) revealed behaviour that is common
to all low-mass X-ray binaries (LMXBs) in the low-hard state. Studies have
shown that neutron star LMXBs exhibit this behaviour at 0.01-1000 keV
luminosities <=10% of the Eddington limit (L_Edd). However, the unabsorbed
0.3-10 keV XBo 144 luminosity was ~0.30 L_Edd for a 1.4 M_sun neutron star, and
the expected 0.01-1000 keV luminosity is 3-7 times higher. We therefore
identify XBo 144 as a black hole candidate. Furthermore, it is the second black
hole candidate to be consistent with formation via tidal capture of a mean
sequence donor in a GC; such systems were previously though non-existent,
because the donor was thought to be disrupted during the capture process.Comment: Accepted for publication in MRAS letters. Four pages, three figure
Neutrino-Deuteron Scattering in Effective Field Theory at Next-to-Next-to Leading Order
We study the four channels associated with neutrino-deuteron breakup
reactions at next-to-next to leading order in effective field theory. We find
that the total cross-section is indeed converging for neutrino energies up to
20 MeV, and thus our calculations can provide constraints on theoretical
uncertainties for the Sudbury Neutrino Observatory. We stress the importance of
a direct experimental measurement to high precision in at least one channel, in
order to fix an axial two-body counterterm.Comment: 32 pages, 14 figures (eps
Collision Dynamics and Solvation of Water Molecules in a Liquid Methanol Film
Environmental molecular beam experiments are used to examine water
interactions with liquid methanol films at temperatures from 170 K to 190 K. We
find that water molecules with 0.32 eV incident kinetic energy are efficiently
trapped by the liquid methanol. The scattering process is characterized by an
efficient loss of energy to surface modes with a minor component of the
incident beam that is inelastically scattered. Thermal desorption of water
molecules has a well characterized Arrhenius form with an activation energy of
0.47{\pm}0.11 eV and pre-exponential factor of 4.6 {\times} 10^(15{\pm}3)
s^(-1). We also observe a temperature dependent incorporation of incident water
into the methanol layer. The implication for fundamental studies and
environmental applications is that even an alcohol as simple as methanol can
exhibit complex and temperature dependent surfactant behavior.Comment: 8 pages, 5 figure
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