1,888 research outputs found
Moment-based analysis of biochemical networks in a heterogeneous population of communicating cells
Cells can utilize chemical communication to exchange information and
coordinate their behavior in the presence of noise. Communication can reduce
noise to shape a collective response, or amplify noise to generate distinct
phenotypic subpopulations. Here we discuss a moment-based approach to study how
cell-cell communication affects noise in biochemical networks that arises from
both intrinsic and extrinsic sources. We derive a system of approximate
differential equations that captures lower-order moments of a population of
cells, which communicate by secreting and sensing a diffusing molecule. Since
the number of obtained equations grows combinatorially with number of
considered cells, we employ a previously proposed model reduction technique,
which exploits symmetries in the underlying moment dynamics. Importantly, the
number of equations obtained in this way is independent of the number of
considered cells such that the method scales to arbitrary population sizes.
Based on this approach, we study how cell-cell communication affects population
variability in several biochemical networks. Moreover, we analyze the accuracy
and computational efficiency of the moment-based approximation by comparing it
with moments obtained from stochastic simulations.Comment: 6 pages, 5 Figure
Neisseria cinerea Expresses a Functional Factor H Binding Protein Which Is Recognized by Immune Responses Elicited by Meningococcal Vaccines
Neisseria meningitidis is a major cause of bacterial meningitis and sepsis worldwide. Capsular polysaccharide vaccines are available against meningococcal serogroups A, C, W, and Y. More recently two protein-based vaccines, Bexsero and Trumenba, against meningococcal serogroup B strains have been licensed; both vaccines contain meningococcal factor H binding protein (fHbp). fHbp is a surface-exposed lipoprotein that binds the negative complement regulator complement factor H (CFH), thereby inhibiting the alternative pathway of complement activation. Recent analysis of available genomes has indicated that some commensal Neisseria species also contain genes that potentially encode fHbp, although the functions of these genes and how immunization with fHbp-containing vaccines could affect the commensal flora have yet to be established. Here, we show that the commensal species Neisseria cinerea expresses functional fHbp on its surface and that it is responsible for recruitment of CFH by the bacterium. N. cinerea fHbp binds CFH with affinity similar to that of meningococcal fHbp and promotes survival of N. cinerea in human serum. We examined the potential impact of fHbp-containing vaccines on N. cinerea. We found that immunization with Bexsero elicits serum bactericidal activity a gainst N. cinerea, which is primarily directed against fHbp. The shared function of fHbp in N. cinerea and N. meningitidis and cross-reactive responses elicited by Bexsero suggest that the introduction of fHbp-containing vaccines has the potential to affect carriage of N. cinerea and other commensal species
Signatures of the Higgs mode in transport through a normal-metal--superconductor junction
A superconductor subject to electromagnetic irradiation in the terahertz
range can show amplitude oscillations of its order parameter. However, coupling
this so-called Higgs mode to the charge current is notoriously difficult. We
propose to achieve such a coupling in a particle-hole-asymmetric configuration
using a DC-voltage-biased normal-metal--superconductor tunnel junction. Using
the quasiclassical Green's function formalism, we demonstrate three
characteristic signatures of the Higgs mode: (i) The AC charge current exhibits
a pronounced resonant behavior and is maximal when the radiation frequency
coincides with the order parameter. (ii) The AC charge current amplitude
exhibits a characteristic nonmonotonic behavior with increasing voltage bias.
(iii) At resonance for large voltage bias, the AC current vanishes inversely
proportional to the bias. These signatures provide an electric detection scheme
for the Higgs mode.Comment: 5.2+3 page
Isospin-conserving hadronic decay of the into
The internal structure of the charm-strange mesons and
are subject of intensive studies. Their widths are small because
they decay dominantly through isospin-breaking hadronic channels
and . The
can also decay into the hadronic final states ,
conserving isospin. In that case there is, however, a strong suppression from
phase space. We study the transition in the
scenario that the is a hadronic molecule. The
final state interaction is taken into account through dispersion relations. We
find that the ratio of the partial widths of the obtained in the
molecular picture is consistent with the existing experimental measurement.
More interestingly, we demonstrate that the invariant mass
distribution shows a double bump structure, which can be used to disentangle
the hadronic molecular picture from the compact state picture for the
. Predictions on the are also
made.Comment: 16 pages, 5 figure
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