6,358 research outputs found
Effect of the length of inflation on angular TT and TE power spectra in power-law inflation
The effect of the length of inflation on the power spectra of scalar and
tensor perturbations is estimated using the power-law inflation model with a
scale factor of a(t) = t^q. Considering various pre-inflation models with
radiation-dominated or scalar matter-dominated periods before inflation in
combination with two matching conditions, the temperature angular power
spectrum (TT) and temperature-polarization cross-power spectrum (TE) are
calculated and a likelihood analysis is performed. It is shown that the
discrepancies between the Wilkinson Microwave Anisotropy Probe (WMAP) data and
the LCDM model, such as suppression of the spectrum at l = 2,3 and oscillatory
behavior, may be explained by the finite length of inflation model if the
length of inflation is near 60 e-folds and q > 300. The proposed models retain
similar values of chi^2 to that achieved by the LCDM model with respect to fit
to the WMAP data, but display different characteristics of the angular TE power
spectra at l < 20.Comment: 41 pages, 11 figure
Phytohaemagglutinin on maternal and umbilical leukocytes
Almost all the umbilical lymphocytes showed more extensive blast cell formation
than that of their mother's lymphocytes with PHA. Pathological conditions of mother in pregnancy and labor such as anemia, gestational toxicosis,
difficult labor and asphyxia of babies, inhibited the normal response of both maternal and umbilical lymphocytes to PHA.</p
On fractionality of the path packing problem
In this paper, we study fractional multiflows in undirected graphs. A
fractional multiflow in a graph G with a node subset T, called terminals, is a
collection of weighted paths with ends in T such that the total weights of
paths traversing each edge does not exceed 1. Well-known fractional path
packing problem consists of maximizing the total weight of paths with ends in a
subset S of TxT over all fractional multiflows. Together, G,T and S form a
network. A network is an Eulerian network if all nodes in N\T have even
degrees.
A term "fractionality" was defined for the fractional path packing problem by
A. Karzanov as the smallest natural number D so that there exists a solution to
the problem that becomes integer-valued when multiplied by D. A. Karzanov has
defined the class of Eulerian networks in terms of T and S, outside which D is
infinite and proved that whithin this class D can be 1,2 or 4. He conjectured
that D should be 1 or 2 for this class of networks. In this paper we prove this
conjecture.Comment: 18 pages, 5 figures in .eps format, 2 latex files, main file is
kc13.tex Resubmission due to incorrectly specified CS type of the article; no
changes to the context have been mad
Interspecific differences in the larval performance of Pieris butterflies (Lepidoptera: Pieridae) are associated with differences in the glucosinolate profiles of host plants
The tremendous diversity of plants and herbivores has arisen from a coevolutionary relationship characterized by plant defense and herbivore counter adaptation. Pierid butterfly species feed on Brassicales plants that produce glucosinolates as a chemical deterrent against herbivory. In turn, the larvae of pierids have nitrile specifier proteins (NSPs) that are expressed in their gut and disarm glucosinolates. Pierid butterflies are known to have diversified in response to glucosinolate diversification in Brassicales. Therefore, each pierid species is expected to have a spectrum of host plants characterized by specific glucosinolate profiles. In this study, we tested whether the larval performance of different Pieris species, a genus in Pieridae (Lepidoptera: Pieridae), was associated with plant defense traits of putative host plants. We conducted feeding assays using larvae of three Pieris species and 10 species of the Brassicaceae family possessing different leaf physical traits and glucosinolate profile measurements. The larvae of Pieris rapae responded differently in the feeding assays compared with the other two Pieris species. This difference was associated with differences in glucosinolate profiles but not with variations in physical traits of the host plants. This result suggests that individual Pieris species are adapted to a subset of glucosinolate profiles within the Brassicaceae. Our results support the idea that the host ranges of Pieris species depend on larval responses to glucosinolate diversification in the host species, supporting the hypothesis of coevolution between butterflies and host plants mediated by the chemical arms race
A Semantic Framework for the Security Analysis of Ethereum smart contracts
Smart contracts are programs running on cryptocurrency (e.g., Ethereum)
blockchains, whose popularity stem from the possibility to perform financial
transactions, such as payments and auctions, in a distributed environment
without need for any trusted third party. Given their financial nature, bugs or
vulnerabilities in these programs may lead to catastrophic consequences, as
witnessed by recent attacks. Unfortunately, programming smart contracts is a
delicate task that requires strong expertise: Ethereum smart contracts are
written in Solidity, a dedicated language resembling JavaScript, and shipped
over the blockchain in the EVM bytecode format. In order to rigorously verify
the security of smart contracts, it is of paramount importance to formalize
their semantics as well as the security properties of interest, in particular
at the level of the bytecode being executed.
In this paper, we present the first complete small-step semantics of EVM
bytecode, which we formalize in the F* proof assistant, obtaining executable
code that we successfully validate against the official Ethereum test suite.
Furthermore, we formally define for the first time a number of central security
properties for smart contracts, such as call integrity, atomicity, and
independence from miner controlled parameters. This formalization relies on a
combination of hyper- and safety properties. Along this work, we identified
various mistakes and imprecisions in existing semantics and verification tools
for Ethereum smart contracts, thereby demonstrating once more the importance of
rigorous semantic foundations for the design of security verification
techniques.Comment: The EAPLS Best Paper Award at ETAP
Initial condition of scalar perturbation in inflation
A formula for the power spectrum of curvature perturbations having any
initial conditions in inflation is obtained. Based on the physical conditions
before inflation, the possibility exists that the initial state of scalar
perturbations is not only the Bunch-Davies state, but also a more general state
(a squeezed state). For example, the derived formula for the power spectrum is
calculated using simple toy cosmological models. When there exists a
radiation-dominated period before inflation, the behavior of the scalar
perturbation is revealed not to vary greatly; however, from large scales to
small scales the power spectrum of the curvature perturbations oscillates
around the normal value. In addition, when inflation has a large break and the
breaking time is a radiation- dominated period, a large enhancement is revealed
to occur which depends on the length of the breaking time.Comment: 24 pages,3 figue
Discrete Convex Functions on Graphs and Their Algorithmic Applications
The present article is an exposition of a theory of discrete convex functions
on certain graph structures, developed by the author in recent years. This
theory is a spin-off of discrete convex analysis by Murota, and is motivated by
combinatorial dualities in multiflow problems and the complexity classification
of facility location problems on graphs. We outline the theory and algorithmic
applications in combinatorial optimization problems
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