69,714 research outputs found
Relations between three-point configuration space shear and convergence statistics
With the growing interest in and ability of using weak lensing studies to
probe the non-Gaussian properties of the matter density field, there is an
increasing need for the study of suitable statistical measures, e.g. shear
three-point statistics. In this paper we establish the relations between the
three-point configuration space shear and convergence statistics, which are an
important missing link between different weak lensing three-point statistics
and provide an alternative way of relating observation and theory. The method
we use also allows us to derive the relations between other two- and
three-point correlation functions. We show the consistency of the relations
obtained with already established results and demonstrate how they can be
evaluated numerically. As a direct application, we use these relations to
formulate the condition for E/B-mode decomposition of lensing three-point
statistics, which is the basis for constructing new three-point statistics
which allow for exact E/B-mode separation. Our work applies also to other
two-dimensional polarization fields such as that of the Cosmic Microwave
Background.Comment: 17 pages, 5 figures, submitted to A&
Origin of the anapole condition as revealed by a simple expansion beyond the toroidal multipole
Toroidal multipoles are a topic of increasing interest in the nanophotonics
and metamaterials communities. In this paper, we separate out the toroidal
multipole components of multipole expansions in polar coordinates (two- and
three-dimensional) by expanding the Bessel or spherical Bessel functions. We
discuss the formation of the lowest order of magnetic anapoles from the
interaction between the magnetic toroidal dipole and the magnetic dipole. Our
method also reveals that there are higher order current configurations other
than the electric toroidal multipole that have the same radiation
characteristics as the pure electric dipole. Furthermore, we find that the
anapole condition requires that there is a perfect cancellation of all higher
order current configurations
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Amino acid residues 24-31 but not palmitoylation of cysteines 30 and 45 are required for membrane anchoring of glutamic acid decarboxylase, GAD65.
The smaller isoform of the GABA synthesizing enzyme glutamic acid decarboxylase, GAD65, is synthesized as a soluble protein that undergoes post-translational modification(s) in the NH2-terminal region to become anchored to the membrane of small synaptic-like microvesicles in pancreatic beta cells, and synaptic vesicles in GABA-ergic neurons. A soluble hydrophilic form, a soluble hydrophobic form, and a hydrophobic firmly membrane-anchored form have been detected in beta cells. A reversible and hydroxylamine sensitive palmitoylation has been shown to distinguish the firmly membrane-anchored form from the soluble yet hydrophobic form, suggesting that palmitoylation of cysteines in the NH2-terminal region is involved in membrane anchoring. In this study we use site-directed mutagenesis to identify the first two cysteines in the NH2-terminal region, Cys 30 and Cys 45, as the sites of palmitoylation of the GAD65 molecule. Mutation of Cys 30 and Cys 45 to Ala results in a loss of palmitoylation but does not significantly alter membrane association of GAD65 in COS-7 cells. Deletion of the first 23 amino acids at the NH2 terminus of the GAD65 30/45A mutant also does not affect the hydrophobicity and membrane anchoring of the GAD65 protein. However, deletion of an additional eight amino acids at the NH2 terminus results in a protein which is hydrophilic and cytosolic. The results suggest that amino acids 24-31 are required for hydrophobic modification and/or targeting of GAD65 to membrane compartments, whereas palmitoylation of Cys 30 and Cys 45 may rather serve to orient or fold the protein at synaptic vesicle membranes
Scalable Coordinated Beamforming for Dense Wireless Cooperative Networks
To meet the ever growing demand for both high throughput and uniform coverage
in future wireless networks, dense network deployment will be ubiquitous, for
which co- operation among the access points is critical. Considering the
computational complexity of designing coordinated beamformers for dense
networks, low-complexity and suboptimal precoding strategies are often adopted.
However, it is not clear how much performance loss will be caused. To enable
optimal coordinated beamforming, in this paper, we propose a framework to
design a scalable beamforming algorithm based on the alternative direction
method of multipliers (ADMM) method. Specifically, we first propose to apply
the matrix stuffing technique to transform the original optimization problem to
an equivalent ADMM-compliant problem, which is much more efficient than the
widely-used modeling framework CVX. We will then propose to use the ADMM
algorithm, a.k.a. the operator splitting method, to solve the transformed
ADMM-compliant problem efficiently. In particular, the subproblems of the ADMM
algorithm at each iteration can be solved with closed-forms and in parallel.
Simulation results show that the proposed techniques can result in significant
computational efficiency compared to the state- of-the-art interior-point
solvers. Furthermore, the simulation results demonstrate that the optimal
coordinated beamforming can significantly improve the system performance
compared to sub-optimal zero forcing beamforming
Vehicle currency
While in principle, international payments could be carried out using any currency or set of currencies, in practice, the U.S. dollar is predominant in international trade and financial flows. The dollar acts as a "vehicle currency" in the sense that agents in nondollar economies will generally engage in currency trade indirectly using the U.S. dollar rather than using direct bilateral trade among their own currencies. Indirect trade is desirable when there are transactions costs of exchange.> ; This paper constructs a dynamic general equilibrium model of a vehicle currency. We explore the nature of the efficiency gains arising from a vehicle currency, and show how this depends on the total number of currencies in existence, the size of the vehicle currency economy, and the monetary policy followed by the vehicle currency's government. We find that there can be very large welfare gains to a vehicle currency in a system of many independent currencies. But these gains are asymmetry weighted towards the residents of the vehicle currency country. The survival of a vehicle currency places natural limits on the monetary policy of the vehicle country.International trade ; Dollar, American ; Equilibrium (Economics) - Mathematical models ; Monetary policy
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