503 research outputs found
Coulombic Energy Transfer and Triple Ionization in Clusters
Using neon and its dimer as a specific example, it is shown that excited
Auger decay channels that are electronically stable in the isolated monomer can
relax in a cluster by electron emission. The decay mechanism, leading to the
formation of a tricationic cluster, is based on an efficient energy-transfer
process from the excited, dicationic monomer to a neighbor. The decay is
ultrafast and expected to be relevant to numerous physical phenomena involving
core holes in clusters and other forms of spatially extended atomic and
molecular matter.Comment: 5 pages, 1 figure, to be published in PR
ASC filament formation serves as a signal amplification mechanism for inflammasomes
A hallmark of inflammasome activation is the ASC speck, a micrometre-sized structure formed by the inflammasome adaptor protein ASC (apoptosis-associated speck-like protein containing a CARD), which consists of a pyrin domain (PYD) and a caspase recruitment domain (CARD). Here we show that assembly of the ASC speck involves oligomerization of ASC(PYD) into filaments and cross-linking of these filaments by ASC(CARD). ASC mutants with a non-functional CARD only assemble filaments but not specks, and moreover disrupt endogenous specks in primary macrophages. Systematic site-directed mutagenesis of ASC(PYD) is used to identify oligomerization-deficient ASC mutants and demonstrate that ASC speck formation is required for efficient processing of IL-1β, but dispensable for gasdermin-D cleavage and pyroptosis induction. Our results suggest that the oligomerization of ASC creates a multitude of potential caspase-1 activation sites, thus serving as a signal amplification mechanism for inflammasome-mediated cytokine production
The group approach to AdS space propagators: A fast algorithm
In this letter we show how the method of [4] for the calculation of two-point
functions in d+1-dimensional AdS space can be simplified. This results in an
algorithm for the evaluation of the two-point functions as linear combinations
of Legendre functions of the second kind. This algorithm can be easily
implemented on a computer. For the sake of illustration, we displayed the
results for the case of symmetric traceless tensor fields with rank up to l=4.Comment: 14 pages, comment adde
Supersymmetric Distributions, Hilbert Spaces of Supersymmetric Functions and Quantum Fields
The recently investigated Hilbert-Krein and other positivity structures of
the superspace are considered in the framework of superdistributions. These
tools are applied to problems raised by the rigorous supersymmetric quantum
field theory.Comment: 24 page
Gravitation on a Homogeneous Domain
Among all plastic deformations of the gravitational Lorentz vacuum \cite{wr1}
a particular role is being played by conformal deformations. These are
conveniently described by using the homogeneous space for the conformal group
SU(2,2)/S(U(2)x U(2)) and its Shilov boundary - the compactified Minkowski
space \tilde{M} [1]. In this paper we review the geometrical structure involved
in such a description. In particular we demonstrate that coherent states on the
homogeneous Kae}hler domain give rise to Einstein-like plastic conformal
deformations when extended to \tilde{M} [2].Comment: 10 pages, 1 figure; four misprints in the original version corrected:
one lacking closing parenthesis, two letters, and an overall sign in front of
the primitive function on p.
Exactly solvable potentials of Calogero type for q-deformed Coxeter groups
We establish that by parameterizing the configuration space of a
one-dimensional quantum system by polynomial invariants of q-deformed Coxeter
groups it is possible to construct exactly solvable models of Calogero type. We
adopt the previously introduced notion of solvability which consists of
relating the Hamiltonian to finite dimensional representation spaces of a Lie
algebra. We present explicitly the -case for which we construct the
potentials by means of suitable gauge transformations.Comment: 22 pages Late
Basis States for Relativistic, Dynamically-Entangled Particles
In several recent papers on entanglement in relativistic quantum systems and
relativistic Bell's inequalities, relativistic Bell-type two-particle states
have been constructed in analogy to non-relativistic states. These
constructions do not have the form suggested by relativistic invariance of the
dynamics. Two relativistic formulations of Bell-type states are shown for
massive particles, one using the standard Wigner spin basis and one using the
helicity basis. The construction hinges on the use of Clebsch-Gordan
coefficients of the Poincar\'e group to reduce the direct product of two
unitary irreducible representations (UIRs) into a direct sum of UIRs.Comment: 19 pages, three tables, revte
The effects of post-pasture woody plant colonization on soil and aboveground litter carbon and nitrogen along a bioclimatic transect
Compressed AFM-IR hyperspectral nanoimaging
Infrared (IR) hyperspectral imaging is a powerful approach in the field of materials and life sciences. However, for the extension to modern sub-diffraction nanoimaging it still remains a highly inefficient technique, as it acquires data via inherent sequential schemes. Here, we introduce the mathematical technique of low-rank matrix reconstruction to the sub-diffraction scheme of atomic force microscopy-based infrared spectroscopy (AFM-IR), for efficient hyperspectral IR nanoimaging. To demonstrate its application potential, we chose the trypanosomatid unicellular parasites Leishmania species as a realistic target of biological importance. The mid-IR spectral fingerprint window covering the spectral range from 1300 to 1900 cm−1 was chosen and a distance between the data points of 220 nm was used for nanoimaging of single parasites. The method of k-means cluster analysis was used for extracting the chemically distinct spatial locations. Subsequently, we randomly selected only 10% of an originally gathered data cube of 134 (x) × 50 (y) × 148 (spectral) AFM-IR measurements and completed the full data set by low-rank matrix reconstruction. This approach shows agreement in the cluster regions between full and reconstructed data cubes. Furthermore, we show that the results of the low-rank reconstruction are superior compared to alternative interpolation techniques in terms of error-metrics, cluster quality, and spectral interpretation for various subsampling ratios. We conclude that by using low-rank matrix reconstruction the data acquisition time can be reduced from more than 14 h to 1–2 h. These findings can significantly boost the practical applicability of hyperspectral nanoimaging in both academic and industrial settings involving nano- and bio-materials
Hair follicles as a target structure for nanoparticles
For at least two decades, nanoparticles have been investigated for their
capability to deliver topically applied substances through the skin barrier.
Based on findings that nanoparticles are highly suitable for penetrating the
blood–brain barrier, their use for drug delivery through the skin has become a
topic of intense research. In spite of the research efforts by academia and
industry, a commercial product permitting the nanoparticle-assisted delivery
of topically applied drugs has not yet been developed. However, nanoparticles
of approximately 600 nm in diameter have been shown to penetrate efficiently
into the hair follicles, where they can be stored for several days. The
successful loading of nanoparticles with drugs and their triggered release
inside the hair follicle may present an ideal method for localized drug
delivery. Depending on the particle size, such a method would permit targeting
specific structures in the hair follicles such as stem cells or immune cells
or blood vessels found in the vicinity of the hair follicles
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