579 research outputs found
Anomalous population of He states in reactions with Li
Structure with the lowest energy observed in the He spectrum populated
in the proton knockout reaction with Li beam has a peak at
MeV. This peak is usually interpreted as a resonant ground state of
He. Our theoretical calculations indicate that this peak is likely to be
a pileup of , , and excitations with very similar shapes. %We
predict a very specific nature of the excitation in He. Moreover,
the ``soft'' excitation appears to be the lowest one in energy. Such an
anomalous continuum response is traced to the halo structure of Li
providing extreme low energy shift to all the expected continuum excitations.
Competitions of the initial state structure (ISS) and the final state
interaction (FSI) effects on the spectrum and three-body correlations in
He are discussed. Analogous effect of the extreme low-energy shift could
also be expected in other cases of emitters populated in reactions with
halo nuclei. Simplified example of the He spectrum in knockout
from Be, is given. We also discuss limits on the properties of He
stemming from the observed He spectrum.Comment: 10 pages, 13 figure
Pauli-principle driven correlations in four-neutron nuclear decays
Mechanism of simultaneous non-sequential four-neutron () emission (or
`true' -decay) has been considered in phenomenological five-body approach.
This approach is analogous to the model of the direct decay to the continuum
often applied to - and -decays. It is demonstrated that -decay
fragments should have specific energy and angular correlations reflecting
strong spatial correlations of `valence' nucleons orbiting in their
-precursors. Due to the Pauli exclusion principle, the valence neutrons are
pushed to the symmetry-allowed configurations in the -precursor structure,
which causes a `Pauli focusing' effect. Prospects of the observation of the
Pauli focusing have been considered for the -precursors H and O.
Fingerprints of their nuclear structure or/and decay dynamics are predicted
Mechanics and Mathematical Modeling of Class III Treatment with Orthodontic Appliances with a Movable Ramp
Treatment of class III is a current problem in orthodontics that requires constant improvement of its methods, development of new or modifications of known methods and techniques. We have developed and studied the modification of removable functionally-directing orthodontic appliances for treatment of Class III, which consists of a plastic base, vestibular arc, retaining clasps, ramp, which is connected with the base by means of two torsion springs. Its usage ensures a prolonged contact of ramp with the teeth. We studied two types of club-shaped springs (torsion springs): one spring, which create an amortization effect during the action of the ramp, but do not change its inclination angle and second one – spring that seek to increase the angle of the ramp inclination due to the disclosure of its curl
Two-proton radioactivity and three-body decay. III. Integral formulae for decay widths in a simplified semianalytical approach
Three-body decays of resonant states are studied using integral formulae for
decay widths. Theoretical approach with a simplified Hamiltonian allows
semianalytical treatment of the problem. The model is applied to decays of the
first excited state of Ne and the ground state of
Fe. The convergence of three-body hyperspherical model calculations to
the exact result for widths and energy distributions are studied. The
theoretical results for Ne and Fe decays are updated and
uncertainties of the derived values are discussed in detail. Correlations for
the decay of Ne state are also studied.Comment: 19 pages, 20 figure
Pharmacological correction of intrarenal hemodynamic disorders in acute kidney injury (part 2)
Evaluate the possibilities of individual pharmacological correction and intensive care of patients with acute kidney injury of different origin. A prospective nonrandomized study. Inclusion criteria: patients with prerenal, renal and subrenal AKI module in stage of oligoanuria and restoration of diuresis. Exclusion criteria: AKI in patients after cardiosurgery and operations on large vessels. Individual pharmacological and non-pharmacological correction (renoprotection) was performed in 250 ICU patients with prerenal (130), renal (81) and subrenal (39) AK
Comment on "Negative Refractive Index in Artificial Metamaterials" [A. N. Grigorenko, Opt. Lett., 31, 2483 (2006)]
A key optical parameter characterizing the existence of negative refraction
in a thin layer of a composite material is the effective refractive index of an
equivalent, homogenized layer with the same physical thickness as the initial
inhomogeneous composite. Measuring the complex transmission and reflection
coefficients is one of the most rigorous ways to obtain this parameter. We
dispute Grigorenko's statement (Optics Letters 31, 2483 (2006)) that measuring
only the reflection intensity spectrum is sufficient for determining the
effective refractive index. We discuss fundamental drawbacks of Grigorenko's
technique of using a best-fit approximation with an a priori prescribed
dispersive behavior for a given metamaterial and an 'effective optical
thickness' that is smaller than the actual thickness of the sample. Our
simulations do not confirm the Grigorenko paper conclusions regarding the
negative refractive index and the negative permeability of the nanopillar
sample in the visible spectral range.Comment: 18 pages, 7 figure
Topological photonics with scattering media
Scattering media, being ubiquitous in nature and critically important for
assessments (e.g., biological tissues), are often considered as nuisance in
optics. Here we show that it is not always the case and scattering media could
be essential in providing elements of topological photonics. We demonstrate
that topological darkness can be realised in the presence of scattering media
due to the transverse nature of electromagnetic waves and the hairy ball
theorem. We describe realizations of topological darkness in a scattering
medium comprising composite gold nanostructures produced by a low-cost
technique of laser structuring of thin metal films. Our results can be useful
for a variety of tasks, including topological nanophotonics, optical label-free
biosensing, and biomedical photonics
Cascaded Optical Field Enhancement in Composite Plasmonic Nanostructures
Copyright © 2010 The American Physical SocietyWe present composite plasmonic nanostructures designed to achieve cascaded enhancement of electromagnetic fields at optical frequencies. Our structures were made with the help of electron-beam lithography and comprise a set of metallic nanodisks placed one above another. The optical properties of reproducible arrays of these structures were studied by using scanning confocal Raman spectroscopy. We show that our composite nanostructures robustly demonstrate dramatic enhancement of the Raman signals when compared to those measured from constituent elements
Cloning and sequence analysis of cDNA for a human homolog of eubacterial ATP-dependent Lon proteases
AbstractOverlapping cDNA clones containing mRNA for a putative Lon protease (LonHS) were isolated from cDNA libraries prepared from human brain poly(A)+ RNA. The determined nucleotide sequence contains a 2814-bp open reading frame with two potential initiation codons (positions 62–64 and 338–340). The 5'-terminal 337-nucleotide fragment of LonHS mRNA is highly enriched with G and C nucleotides and could direct synthesis of the LonHS N-terminal domain. More likely this region promotes initiation of protein synthesis from the second AUG codon in a cap-independent manner. The amino acid sequence initiated at the second AUG codon includes 845 residues, over 30% of which are identical to those of eubacterial Lon proteases. Residues of the ‘A’ and ‘B’ motifs of NTP-binding pattern and a plausible catalytic serine residue are conserved in LonHS. Northern blot analysis revealed LonHS mRNA in lung, duodenum, liver and heart, but not in thymus cells
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