307 research outputs found
Five-Torsion in the Homology of the Matching Complex on 14 Vertices
J. L. Andersen proved that there is 5-torsion in the bottom nonvanishing
homology group of the simplicial complex of graphs of degree at most two on
seven vertices. We use this result to demonstrate that there is 5-torsion also
in the bottom nonvanishing homology group of the matching complex on
14 vertices. Combining our observation with results due to Bouc and to
Shareshian and Wachs, we conclude that the case is exceptional; for all
other , the torsion subgroup of the bottom nonvanishing homology group has
exponent three or is zero. The possibility remains that there is other torsion
than 3-torsion in higher-degree homology groups of when and .Comment: 11 page
Subthreshold dynamics of the neural membrane potential driven by stochastic synaptic input
In the cerebral cortex, neurons are subject to a continuous bombardment of synaptic inputs originating from the network's background activity. This leads to ongoing, mostly subthreshold membrane dynamics that depends on the statistics of the background activity and of the synapses made on a neuron. Subthreshold membrane polarization is, in turn, a potent modulator of neural responses. The present paper analyzes the subthreshold dynamics of the neural membrane potential driven by synaptic inputs of stationary statistics. Synaptic inputs are considered in linear interaction. The analysis identifies regimes of input statistics which give rise to stationary, fluctuating, oscillatory, and unstable dynamics. In particular, I show that (i) mere noise inputs can drive the membrane potential into sustained, quasiperiodic oscillations (noise-driven oscillations), in the absence of a stimulus-derived, intraneural, or network pacemaker; (ii) adding hyperpolarizing to depolarizing synaptic input can increase neural activity (hyperpolarization-induced activity), in the absence of hyperpolarization-activated currents
The Dirac system on the Anti-de Sitter Universe
We investigate the global solutions of the Dirac equation on the
Anti-de-Sitter Universe. Since this space is not globally hyperbolic, the
Cauchy problem is not, {\it a priori}, well-posed. Nevertheless we can prove
that there exists unitary dynamics, but its uniqueness crucially depends on the
ratio beween the mass of the field and the cosmological constant
: it appears a critical value, , which plays a role
similar to the Breitenlohner-Freedman bound for the scalar fields. When
there exists a unique unitary dynamics. In opposite, for
the light fermions satisfying , we construct several asymptotic
conditions at infinity, such that the problem becomes well-posed. In all the
cases, the spectrum of the hamiltonian is discrete. We also prove a result of
equipartition of the energy.Comment: 33 page
An optimal gap theorem
By solving the Cauchy problem for the Hodge-Laplace heat equation for
-closed, positive -forms, we prove an optimal gap theorem for
K\"ahler manifolds with nonnegative bisectional curvature which asserts that
the manifold is flat if the average of the scalar curvature over balls of
radius centered at any fixed point is a function of .
Furthermore via a relative monotonicity estimate we obtain a stronger
statement, namely a `positive mass' type result, asserting that if is
not flat, then for any
Antiflow of kaons in relativistic heavy ion collisions
We compare relativistic transport model calculations to recent data on the
sideward flow of neutral strange K^0_s mesons for Au+Au collisions at 6 AGeV. A
soft nuclear equation of state is found to describe very well the positive
proton flow data measured in the same experiment. In the absence of kaon
potential, the K^0 flow pattern is similar to that of protons. The kaon flow
becomes negative if a repulsive kaon potential determined from the impulse
approximation is introduced. However, this potential underestimates the data
which exhibits larger antiflow. An excellent agreement with the data is
obtained when a relativistic scalar-vector kaon potential, that has stronger
density dependence, is used. We further find that the transverse momentum
dependence of directed and elliptic flow is quite sensitive to the kaon
potential in dense matter.Comment: 5 pages, Revtex, 4 figure
Growth of the hatchery-produced juveniles of commercial sea cucumber Holothuria (Theelothuria) spinifera Theel
Density dependent hadron field theory for neutron stars with antikaon condensates
We investigate and condensation in -equilibrated
hyperonic matter within a density dependent hadron field theoretical model. In
this model, baryon-baryon and (anti)kaon-baryon interactions are mediated by
the exchange of mesons. Density dependent meson-baryon coupling constants are
obtained from microscopic Dirac Brueckner calculations using Groningen and Bonn
A nucleon-nucleon potential. It is found that the threshold of antikaon
condensation is not only sensitive to the equation of state but also to
antikaon optical potential depth. Only for large values of antikaon optical
potential depth, condensation sets in even in the presence of negatively
charged hyperons. The threshold of condensation is always reached
after condensation. Antikaon condensation makes the equation of state
softer thus resulting in smaller maximum mass stars compared with the case
without any condensate.Comment: 20 pages, 7 figures; final version to appear in Physical Review
Clinical and laboratory variability in a cohort of patients diagnosed with type 1 VWD in the United States
Von Willebrand disease (VWD) is the most common inherited bleeding disorder, and type 1
VWD is the most common VWD variant. Despite its frequency, diagnosis of type 1 VWD
remains the subject of much debate. In order to study the spectrum of type 1 VWD in the United
States, the Zimmerman Program enrolled 482 subjects with a previous diagnosis of type 1 VWD
without stringent laboratory diagnostic criteria. VWF laboratory testing and full length VWF
gene sequencing were performed for all index cases and healthy control subjects in a central
laboratory. Bleeding phenotype was characterized using the ISTH Bleeding Assessment Tool.
At study entry, 64% of subjects had VWF:Ag or VWF:RCo below the lower limit of normal,
while 36% had normal VWF levels. VWF sequence variations were most frequent in subjects
with VWF:Ag < 30 IU/dL (82%) while subjects with type 1 VWD and VWF:Ag ≥ 30 IU/dL had
an intermediate frequency of variants (44%). Subjects whose VWF testing was normal at study
entry had a similar rate of sequence variations as the healthy controls at 14% of subjects. All
subjects with severe type 1 VWD and VWF:Ag ≤ 5 IU/dL had an abnormal bleeding score, but
otherwise bleeding score did not correlate with VWF:Ag level. Subjects with a historical
diagnosis of type 1 VWD had similar rates of abnormal bleeding scores compared to subjects
with low VWF levels at study entry. Type 1 VWD in the United States is highly variable, and
bleeding symptoms are frequent in this population
MultiCellDS : a community-developed standard for curating microenvironment-dependent multicellular data
Exchanging and understanding scientific data and their context represents a significant barrier to advancing research, especially with respect to information siloing. Maintaining information provenance and providing data curation and quality control help overcome common concerns and barriers to the effective sharing of scientific data. To address these problems in and the unique challenges of multicellular systems, we assembled a panel composed of investigators from several disciplines to create the MultiCellular Data Standard (MultiCellDS) with a use-case driven development process. The standard includes (1) digital cell lines, which are analogous to traditional biological cell lines, to record metadata, cellular microenvironment, and cellular phenotype variables of a biological cell line, (2) digital snapshots to consistently record simulation, experimental, and clinical data for multicellular systems, and (3) collections that can logically group digital cell lines and snapshots. We have created a MultiCellular DataBase (MultiCellDB) to store digital snapshots and the 200+ digital cell lines we have generated. MultiCellDS, by having a fixed standard, enables discoverability, extensibility, maintainability, searchability, and sustainability of data, creating biological applicability and clinical utility that permits us to identify upcoming challenges to uplift biology and strategies and therapies for improving human health
Antikaon condensation and the metastability of protoneutron stars
We investigate the condensation of meson along with
condensation in the neutrino trapped matter with and without hyperons.
Calculations are performed in the relativistic mean field models in which both
the baryon-baryon and (anti)kaon-baryon interactions are mediated by meson
exchange. In the neutrino trapped matter relevant to protoneutron stars, the
critical density of condensation is shifted considerably to higher
density whereas that of condensation is shifted slightly to higher
density with respect to that of the neutrino free case. The onset of
condensation always occurs earlier than that of condensation. A
significant region of maximum mass protoneutron stars is found to contain condensate for larger values of the antikaon potential. With the
appearance of condensation, there is a region of symmetric nuclear
matter in the inner core of a protoneutron star. It is found that the maximum
mass of a protoneutron star containing and condensate is
greater than that of the corresponding neutron star. We revisit the implication
of this scenario in the context of the metastability of protoneutron stars and
their evolution to low mass black holes.Comment: 26 pages; Revtex; 8 figures include
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