A review and evaluation of the Langley Research Center's Scientific and Technical Information Program. Results of phase 5. Design and evaluation of STI systems: A selected, annotated bibliography

A selected, annotated bibliography of literature citations related to the design and evaluation of STI systems is presented. The use of manual and machine-readable literature searches; the review of numerous books, periodicals reports, and papers; and the selection and annotation of literature citations were required. The bibliography was produced because the information was needed to develop the methodology for the review and evaluation project, and a survey of the literature did not reveal the existence of a single published source of information pertinent to the subject. Approximately 200 citations are classified in four subject areas. The areas include information - general; information systems - design and evaluation, including information products and services; information - use and need; and information - economics

Perturbative fragmentation of vector colored particle into bound states with a heavy antiquark

The fragmentation function of vector particle into possible bound S-wave states with a heavy antiquark is calculated in the leading order of perturbative QCD for the high energy processes at large transverse momenta with the different behaviour of anomalous chromomagnetic moment. One-loop equations are derived for the evolution of fragmentation function moments, which is caused by the emission of hard gluons by the vector particle. The integrated probabilities of fragmentation are given. The distribution of bound state over the transverse momentum with respect to the axis of fragmentation is calculated in the scaling limit.Comment: 10 pages, Latex file + 4 ps-figure

The Drell-Yan process and Deep Inelastic Scattering from the lattice

We report on measurements of the h_1 structure function, relevant to calculating cross-sections for the Drell-Yan process. This is a quantity which can not be measured in Deep Inelastic Scattering, it gives additional information on the spin carried by the valence quarks, as well as insights on how relativistic the quarks are.Comment: 3 pages, Latex, 3 figures, espcrc2.sty included, Talk presented at LATTICE96(phenomenology

Existence of Multiple Vortices in Supersymmetric Gauge Field Theory

Two sharp existence and uniqueness theorems are presented for solutions of multiple vortices arising in a six-dimensional brane-world supersymmetric gauge field theory under the general gauge symmetry group $G=U(1)\times SU(N)$ and with $N$ Higgs scalar fields in the fundamental representation of $G$. Specifically, when the space of extra dimension is compact so that vortices are hosted in a 2-torus of volume |\Om|, the existence of a unique multiple vortex solution representing $n_1,...,n_N$ respectively prescribed vortices arising in the $N$ species of the Higgs fields is established under the explicitly stated necessary and sufficient condition \[ n_i<\frac{g^2v^2}{8\pi N}|\Om|+\frac{1}{N}(1-\frac{1}{N}[\frac{g}{e}]^2)n,\quad i=1,...,N,] where $e$ and $g$ are the U(1) electromagnetic and SU(N) chromatic coupling constants, $v$ measures the energy scale of broken symmetry, and $n=\sum_{i=1}^N n_i$ is the total vortex number; when the space of extra dimension is the full plane, the existence and uniqueness of an arbitrarily prescribed $n$-vortex solution of finite energy is always ensured. These vortices are governed by a system of nonlinear elliptic equations, which may be reformulated to allow a variational structure. Proofs of existence are then developed using the methods of calculus of variations.Comment: 23 page

Accounting for cellular heterogeneity is critical in epigenome-wide association studies

Background: Epigenome-wide association studies of human disease and other quantitative traits are becoming increasingly common. A series of papers reporting age-related changes in DNA methylation profiles in peripheral blood have already been published. However, blood is a heterogeneous collection of different cell types, each with a very different DNA methylation profile. Results: Using a statistical method that permits estimating the relative proportion of cell types from DNA methylation profiles, we examine data from five previously published studies, and find strong evidence of cell composition change across age in blood. We also demonstrate that, in these studies, cellular composition explains much of the observed variability in DNA methylation. Furthermore, we find high levels of confounding between age-related variability and cellular composition at the CpG level. Conclusions: Our findings underscore the importance of considering cell composition variability in epigenetic studies based on whole blood and other heterogeneous tissue sources. We also provide software for estimating and exploring this composition confounding for the Illumina 450k microarray

Emergent Chiral Symmetry: Parity and Time Reversal Doubles

There are numerous examples of approximately degenerate states of opposite parity in molecular physics. Theory indicates that these doubles can occur in molecules that are reflection-asymmetric. Such parity doubles occur in nuclear physics as well, among nuclei with odd A $\sim$ 219-229. We have also suggested elsewhere that such doubles occur in particle physics for baryons made up of `cbu' and `cbd' quarks. In this article, we discuss the theoretical foundations of these doubles in detail, demonstrating their emergence as a surprisingly subtle consequence of the Born-Oppenheimer approximation, and emphasizing their bundle-theoretic and topological underpinnings. Starting with certain ``low energy'' effective theories in which classical symmetries like parity and time reversal are anomalously broken on quantization, we show how these symmetries can be restored by judicious inclusion of ``high-energy'' degrees of freedom. This mechanism of restoring the symmetry naturally leads to the aforementioned doublet structure. A novel by-product of this mechanism is the emergence of an approximate symmetry (corresponding to the approximate degeneracy of the doubles) at low energies which is not evident in the full Hamiltonian. We also discuss the implications of this mechanism for Skyrmion physics, monopoles, anomalies and quantum gravity.Comment: 32 pages, latex. minor changes in presentation and reference

Fermionic zero modes in self-dual vortex background

We study fermionic zero modes in the background of self-dual vortex on a two-dimensional non-compact extra space in 5+1 dimensions. In the Abelian Higgs model, we present an unified description of the topological and non-topological self-dual vortex on the extra two dimensions. Based on it, we study localization of bulk fermions on a brane with inclusion of Yang-Mills and gravity backgrounds in six dimensions. Through two simple cases, it is shown that the vortex background contributes a phase shift to the fermionic zero mode, this phase is actually origin from the Aharonov-Bohm effect.Comment: 11 pages, no figures, to appear in MPL

The Nucleon ``Tensor Charges'' and the Skyrme Model

The lowest moment of the twist-two, chiral-odd parton distribution $h_1(x)$ of the nucleon can be related to the so-called ``tensor charges'' of the nucleon. We consider the tensor charges in the Skyrme model, and find that in the large-$N_c$, SU(3)-symmetric limit, the model predicts that the octet isosinglet tensor charge, $g^8_T$, is of order $1/N_c$ with respect to the octet isovector tensor charge, $g^3_T$. The predicted $F/D$ ratio is then 1/3, in the large-$N_c$ limit. These predictions coincide with the Skyrme model predictions for the octet ${\it axial}$ charges, $g^8_A$ and $g^3_A$. (The prediction $F/D=1/3$ for the axial charges differs from the commonly quoted prediction of 5/9, which is based on an inconsistent treatment of the large-$N_c$ limit.) The model also predicts that the singlet tensor charge, $g^0_T$, is of order $1/N_c$ with respect to $g^3_T$.Comment: 9 single-spaced pages, no figures, MIT-CTP-212

Constraints on the large-x d/u ratio from electron-nucleus scattering at x>1

Recently the ratio of neutron to proton structure functions F_2n/F_2p was extracted from a phenomenological correlation between the strength of the nuclear EMC effect and inclusive electron-nucleus cross section ratios at x>1. Within conventional models of nuclear smearing, this "in-medium correction" (IMC) extraction constrains the size of nuclear effects in the deuteron structure functions, from which the neutron structure function F_2n is usually extracted. The IMC data determine the resulting proton d/u quark distribution ratio, extrapolated to x=1, to be 0.23 +- 0.09 with a 90% confidence level. This is well below the SU(6) symmetry limit of 1/2 and significantly above the scalar diquark dominance limit of 0.Comment: 4 pages, 3 figure

The Relative Importance of Different Trophic Pathways for Secondary Exposure to Anticoagulant Rodenticides

Secondary exposure of predators to anticoagulant rodenticides, and in particular second generation anticoagulant rodenticides (SGARs), is a global phenomenon. The widespread and large-scale nature of this exposure has attracted considerable concern, although the consequences in terms of likelihood of poisoning of individuals and resultant impacts on populations are not well characterised. Secondary exposure of predators may as rise from once or more of: (i) eating contaminated commensal rodents subject to control (target species are typically rats and house mice); (ii) consumption of contaminated non-target small mammals (such as Peromyscus, Microtus, and Apodemus species) that encounter and feed on what are rodent-attractive baits; (iii) consumption of non-rodent vertebrate and invertebrate prey that may also incidentally encounter and eat baits. We hypothesised that predators feeding primarily on target species may be most at risk of exposure to SGARs while those predominantly taking non-mammalian prey may be at least risk. We tested this hypothesis by comparing exposure, determined from the presence and magnitude of SGAR liver residues, in red kites (Milvus milvus), which feeds extensively on rats, in barn owls (Tyto alba), kestrels (Falco tinnunculus), and tawny owls (Strix aluco) that feed widely on non-target small mammals, and in sparrowhawks (Accipiter nisus) that feed predominantly on small birds. We found that the scale and magnitude of exposure was broadly consistent with our hypothesis, and that controlling for age in the analysis could be important as older birds can accumulate residues with age. However, exposure in kestrels was typically greater than that in barn owls and tawny owls, despite what is thought to be a general similarity among the species in their diets. We discuss the relative importance of trophic pathways relative to other factors that may drive secondary exposure in predators, and confirm that species that feed on rats or other target species may be at most risk of exposure and poisoning