Apparatus for measuring an aircraft's speed and height

An apparatus for measuring aircraft horizontal speed and height above ground without the need for airborne cooperative devices is presented. Two ground level TV cameras separated by a measured distance and pointed at zenith are placed in line with the projection of the expected path of the aircraft. Speed is determined by measuring the time that it takes the aircraft to travel between the fields of view of the two TV cameras using zenith crossings as the reference points. Height is determined by correlating the speed with the time required to cross the field of view of either of the two cameras

Radiation Reaction fields for an accelerated dipole for scalar and electromagnetic radiation

The radiation reaction fields are calculated for an accelerated changing dipole in scalar and electromagnetic radiation fields. The acceleration reaction is shown to alter the damping of a time varying dipole in the EM case, but not the scalar case. In the EM case, the dipole radiation reaction field can exert a force on an accelerated monopole charge associated with the accelerated dipole. The radiation reaction of an accelerated charge does not exert a torque on an accelerated magnetic dipole, but an accelerated dipole does exert a force on the charge. The technique used is that originally developed by Penrose for non-singular fields and extended by the author for an accelerated monopole charge.Comment: 11 page

Multivariate Fitting and the Error Matrix in Global Analysis of Data

When a large body of data from diverse experiments is analyzed using a theoretical model with many parameters, the standard error matrix method and the general tools for evaluating errors may become inadequate. We present an iterative method that significantly improves the reliability of the error matrix calculation. To obtain even better estimates of the uncertainties on predictions of physical observables, we also present a Lagrange multiplier method that explores the entire parameter space and avoids the linear approximations assumed in conventional error propagation calculations. These methods are illustrated by an example from the global analysis of parton distribution functions.Comment: 13 pages, 5 figures, Latex; minor clarifications, fortran program made available; Normalization of Hessian matrix changed to HEP standar

Exotic quark effects on the Higgs sector of the USSM at the LHC

The Higgs sector of the U(1)-extended supersymmetric model is studied with great detail. We calculate the masses of the Higgs bosons at the one-loop level. We also calculate at the one-loop level the gluon-involving processes for the productions and decays of the scalar Higgs bosons of the model at the energy of the CERN Large Hadron Collider (LHC), where the radiative corrections due to the loops of top, bottom, and exotic quarks and their scalar partners are taken into account. We find that the exotic quark and exotic scalar quarks in the model may manifest themselves at the LHC, since the production of the heaviest scalar Higgs boson via gluon fusion processes is mediated virtually by the loops of exotic quark and exotic scalar quarks, for a reasonable parameter set of the model.Comment: 36 pages, 13 figures, JP

Uncertainties of predictions from parton distribution functions II: the Hessian method

We develop a general method to quantify the uncertainties of parton distribution functions and their physical predictions, with emphasis on incorporating all relevant experimental constraints. The method uses the Hessian formalism to study an effective chi-squared function that quantifies the fit between theory and experiment. Key ingredients are a recently developed iterative procedure to calculate the Hessian matrix in the difficult global analysis environment, and the use of parameters defined as components along appropriately normalized eigenvectors. The result is a set of 2d Eigenvector Basis parton distributions (where d=16 is the number of parton parameters) from which the uncertainty on any physical quantity due to the uncertainty in parton distributions can be calculated. We illustrate the method by applying it to calculate uncertainties of gluon and quark distribution functions, W boson rapidity distributions, and the correlation between W and Z production cross sections.Comment: 30 pages, Latex. Reference added. Normalization of Hessian matrix changed to HEP standar

Prevalence of Advanced, Precancerous Colorectal Neoplasms in Black and White Populations: A Systematic Review and Meta-analysis

Background & Aims Colorectal cancer (CRC) incidence and mortality are higher in black vs white populations. The reasons for these disparities are not clear, yet some guidelines recommend screening black persons for CRC starting at ages 40–45 years. We performed a systematic review and meta-analysis to compare the prevalence of advanced adenomas (AAs) and advanced, precancerous colorectal neoplasms (ACNs) between asymptomatic black and white screen-eligible adults. Methods We searched Ovid MEDLINE, PubMed, Embase, and the Cochrane Library to identify articles (published from 1946 through June 2017) that reported prevalence values of AA or ACN in average-risk black and white individuals undergoing screening colonoscopy. Two authors independently assessed study quality and risk for bias using a modified validated quality assessment instrument. Following the PRISMA guidelines, 2 authors independently abstracted descriptive and quantitative data from each study. We performed a random effects meta-analysis to determine risk differences and odds ratios (ORs). Results From 1653 articles, we identified 9 studies for analysis, comprising 302,128 individuals. Six of the 9 studies were of high methodological quality, had a low risk for bias, and were included in the meta-analysis. In these 9 studies, the overall prevalence values for AA and ACN did not differ significantly between back (6.57%) and white screened individuals (6.20%; OR, 1.03; 95% CI, 0.81–1.30). Among a subgroup of 5 studies, the prevalence of proximal AA and ACN was significantly higher in black (3.30%) than in white screened individuals (2.42%; OR, 1.20; 95% CI, 1.12–1.30). Excluding the largest study did not affect overall prevalence (OR, 0.99; CI, 0.73–1.34) but eliminated the difference in prevalence of proximal AA or ACN (OR, 1.48; 95% CI, 0.87–2.52). Conclusions In a meta-analysis, we found the overall prevalence of AA and ACN did not differ significantly between average-risk black and white persons, indicating that the age at which to begin CRC screening need not differ based on race

Higgs boson production with one bottom quark jet at hadron colliders

We present total rates and kinematic distributions for the associated production of a single bottom quark and a Higgs boson at the Tevatron and the LHC. We include next-to-leading order QCD corrections and compare the results obtained in the four and five flavor number schemes for parton distribution functions.Comment: 4 pages, 8 figures, RevTeX

Lunar lander conceptual design

This paper is a first look at the problems of building a lunar lander to support a small lunar surface base. A series of trade studies was performed to define the lander. The initial trades concerned choosing number of stages, payload mass, parking orbit altitude, and propellant type. Other important trades and issues included plane change capability, propellant loading and maintenance location, and reusability considerations. Given a rough baseline, the systems were then reviewed. A conceptual design was then produced. The process was carried through only one iteration. Many more iterations are needed. A transportation system using reusable, aerobraked orbital transfer vehicles (OTV's) is assumed. These OTV's are assumed to be based and maintained at a low Earth orbit (LEO) space station, optimized for transportation functions. Single- and two-stage OTV stacks are considered. The OTV's make the translunar injection (TLI), lunar orbit insertion (LOI), and trans-Earth injection (TEI) burns, as well as midcourse and perigee raise maneuvers