2,328 research outputs found
Extracellular Protons Inhibit Charge Immobilization in the Cardiac Voltage-Gated Sodium Channel
AbstractLow pH depolarizes the voltage-dependence of cardiac voltage-gated sodium (NaV1.5) channel activation and fast inactivation and destabilizes the fast-inactivated state. The molecular basis for these changes in protein behavior has not been reported. We hypothesized that changes in the kinetics of voltage sensor movement may destabilize the fast-inactivated state in NaV1.5. To test this idea, we recorded NaV1.5 gating currents in Xenopus oocytes using a cut-open voltage-clamp with extracellular solution titrated to either pH 7.4 or pH 6.0. Reducing extracellular pH significantly depolarized the voltage-dependence of both the QON/V and QOFF/V curves, and reduced the total charge immobilized during depolarization. We conclude that destabilized fast-inactivation and reduced charge immobilization in NaV1.5 at low pH are functionally related effects
Implementation of a wind-farm specific operational wave forecasting tool in the North-Sea: methods and forcing sensitivity
Water Qualit
Acoustic deterrents influence foraging activity, flight and echolocation behaviour of free-flying bats
Combinations of DIPs and Dprs control organization of olfactory receptor neuron terminals in Drosophila
In Drosophila, 50 classes of olfactory receptor neurons (ORNs) connect to 50 class-specific and uniquely positioned glomeruli in the antennal lobe. Despite the identification of cell surface receptors regulating axon guidance, how ORN axons sort to form 50 stereotypical glomeruli remains unclear. Here we show that the heterophilic cell adhesion proteins, DIPs and Dprs, are expressed in ORNs during glomerular formation. Many ORN classes express a unique combination of DIPs/dprs, with neurons of the same class expressing interacting partners, suggesting a role in class-specific self-adhesion between ORN axons. Analysis of DIP/Dpr expression revealed that ORNs that target neighboring glomeruli have different combinations, and ORNs with very similar DIP/Dpr combinations can project to distant glomeruli in the antennal lobe. DIP/Dpr profiles are dynamic during development and correlate with sensilla type lineage for some ORN classes. Perturbations of DIP/dpr gene function result in local projection defects of ORN axons and glomerular positioning, without altering correct matching of ORNs with their target neurons. Our results suggest that context-dependent differential adhesion through DIP/Dpr combinations regulate self-adhesion and sort ORN axons into uniquely positioned glomeruli
Selected nucleon form factors and a composite scalar diquark
A covariant, composite scalar diquark, Fadde'ev amplitude model for the
nucleon is used to calculate pseudoscalar, isoscalar- and isovector-vector,
axial-vector and scalar nucleon form factors. The last yields the nucleon
sigma-term and on-shell sigma-nucleon coupling. The calculated form factors are
soft, and the couplings are generally in good agreement with experiment and
other determinations. Elements in the dressed-quark-axial-vector vertex that
are not constrained by the Ward-Takahashi identity contribute ~20% to the
magnitude of g_A. The calculation of the nucleon sigma-term elucidates the only
unambiguous means of extrapolating meson-nucleon couplings off the meson
mass-shell.Comment: 12 pages, REVTEX, 5 figures, epsfi
High-energy gamma-ray emission from the inner jet of LS I+61 303: the hadronic contribution revisited
LS I+61 303 has been detected by the Cherenkov telescope MAGIC at very high
energies, presenting a variable flux along the orbital motion with a maximum
clearly separated from the periastron passage. In the light of the new
observational constraints, we revisit the discussion of the production of
high-energy gamma rays from particle interactions in the inner jet of this
system. The hadronic contribution could represent a major fraction of the TeV
emission detected from this source. The spectral energy distribution resulting
from p-p interactions is recalculated. Opacity effects introduced by the photon
fields of the primary star and the stellar decretion disk are shown to be
essential in shaping the high-energy gamma-ray light curve at energies close to
200 GeV. We also present results of Monte Carlo simulations of the
electromagnetic cascades developed very close to the periastron passage. We
conclude that a hadronic microquasar model for the gamma-ray emission in LS I
+61 303 can reproduce the main features of its observed high-energy gamma-ray
flux.Comment: 6 pages. Sligth improvements made. Accepted version by Astrophysics
and Space Scienc
Reduction of Couplings in Quantum Field Theories with applications in Finite Theories and the MSSM
We apply the method of reduction of couplings in a Finite Unified Theory and
in the MSSM. The method consists on searching for renormalization group
invariant relations among couplings of a renormalizable theory holding to all
orders in perturbation theory. It has a remarkable predictive power since, at
the unification scale, it leads to relations between gauge and Yukawa couplings
in the dimensionless sectors and relations involving the trilinear terms and
the Yukawa couplings, as well as a sum rule among the scalar masses and the
unified gaugino mass in the soft breaking sector. In both the MSSM and the FUT
model we predict the masses of the top and bottom quarks and the light Higgs in
remarkable agreement with the experiment. Furthermore we also predict the
masses of the other Higgses, as well as the supersymmetric spectrum, both being
in very confortable agreement with the LHC bounds on Higgs and supersymmetric
particles.Comment: 18 pages, 4 figures. To appear in the proceedings of LT-10, Varna.
Based on invited talks given at: LT-10, Varna; PACT-2013, Madrid; SQS'2013,
Dubna; CORFU 2013, Corfu, and in several invited seminar
Superconformal Ward Identities and N=2 Yang-Mills Theory
A reformulation of the superconformal Ward identities that combines all the
superconformal currents and the associated parameters in one multiplet is given
for theories with rigid N=1 or N=2 supersymmetry. This form of the Ward
Identities is applied to spontaneously broken N=2 Yang-Mills theory and used to
derive a condition on the low energy effective action. This condition is
satisfied by the solution proposed by Seiberg and Witten.Comment: 25 pages, plain Te
Evaluation of bioadhesive capacity and immunoadjuvant properties of vitamin B(12)-Gantrez nanoparticles.
PURPOSE: To design bioadhesive Gantrez AN (poly[methyl vinyl ether-co-maleic
anhydride], PVM/MA) nanoparticles (NP) coated with Vitamin B12 (Vit B12), and
investigate their application in oral antigen delivery.
METHODS: The association of Vit B12 to Gantrez AN nanoparticles was performed by
the direct attachment of reactive Vit B12 to the surface of the nanoparticles (NPB), or
linking to the copolymer chains in dimethylformamide prior to NP formation (NPBDMF).
Nanoparticles were characterized by measuring the size, zeta potential, Vit B12
association efficacy, and stability of Vit B12 on the surface of the nanoparticles. In vivo
bioadhesion study was performed by the oral administration of fluorescently-labeled
nanoparticle formulations to rats. Both systemic and mucosal immune responses were
evaluated after oral and subcutaneous immunization with ovalbumin (OVA) containing
Vit B12-coated nanoparticles.
RESULTS: The Vit B12 nanoparticles displayed homogenous size distribution with a
mean diameter of about 200 nm and a negative surface charge. The association
efficiency of Vit B12 to NPB-DMF formulation was about two times higher than to the
NPB, showing also a higher surface stability of Vit B12. The bioadhesion study
demonstrated that NPB-DMF had an important tropism to the distal portions of the gut,
which was about 2 and 3.5 times higher than the tropism observed for NPB and control
NP, respectively (P< 0.05). Oral administration of OVA-NPB-DMF induced also
stronger and more balanced serum anti-OVA titers of IgG2a (Th1) and IgG1 (Th2)
compared to control OVA-NP. In addition, oral immunization with OVA-NPB-DMF
induced a higher mucosal IgA response than subcutaneous administration.
CONCLUSIONS: These results indicate the benefits of bioadhesive Vit B12-coated
nanoparticles in oral antigen delivery eliciting systemic and mucosal immune response
The twin paradox and Mach's principle
The problem of absolute motion in the context of the twin paradox is
discussed. It is shown that the various versions of the clock paradox feature
some aspects which Mach might have been appreciated. However, the ultimate
cause of the behavior of the clocks must be attributed to the autonomous status
of spacetime, thereby proving the relational program advocated by Mach as
impracticable.Comment: Latex2e, 11 pages, 6 figures, 33 references, no tables. Accepted for
publication in The European Physical Journal PLUS (EPJ PLUS
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