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

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

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

Collider Signature of Bulk Neutrinos in Large Extra Dimensions

We consider the collider signature of right-handed neutrinos propagating in $\delta$ (large) extra dimensions, and interacting with Standard Model fields only through a Yukawa coupling to the left-handed neutrino and the Higgs boson. These theories are attractive as they can explain the smallness of the neutrino mass, as has already been shown. We show that if $\delta$ is bigger than two, it can result in an enhancement in the production rate of the Higgs boson, decaying either invisibly or to a $b$ anti-$b$ quark pair, associated with an isolated high $p_T$ charged lepton and missing transverse energy at future hadron colliders, such as the LHC. The enhancement is due to the large number of Kaluza-Klein neutrinos produced in the final state. The observation of the signal event would provide an opportunity to distinguish between the normal and inverted neutrino mass hierarchies, and to determine the absolute scale of neutrino masses by measuring the asymmetry of the observed event numbers in the electron and muon channels.Comment: 31 pages, 13 figures. v2: Added discussion on PDF uncertainties, added reference

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

The Relationships Between School Poverty and Student Achievement in Maine

The goal of this study was to examine the relationships between school level poverty found in Maine schools and student academic performance. The evidence clearly shows that there is a relationship. As the percent of poverty increases in a school, student performance declines. But the poverty level alone does not explain the wide variations in performance found across the state. The level of poverty in a school is the single best predictor of average student performance, but other factors also play a role in influencing student achievement. Some of these factors include the type of school students are enrolled in, years of teaching experience of the school staff, and the education levels of teachers. Evidence was also found for some higher poverty schools that were defying the odds. Even with higher levels of poverty in their schools, these schools were successful in producing higher levels of student performance. Two additional characteristics were discovered for student performance in higher poverty schools. First, overall performance differs in K-8 and middle schools. The negative relationship between poverty levels and performance is weaker for K-8 schools. More of the higher poverty K-8 schools are performing better than higher poverty middle schools. Second, the levels of poverty found in schools not only affected children in poverty but also those not in poverty. Students in higher poverty schools who do not qualify for free or reduced lunches do not perform as well as their cohorts in lower poverty schools. What is unclear are the causes of this lower performance of non-poverty children in higher poverty schools. Without question, the evidence examined in this study indicates that levels of school poverty and average student achievement are related. The magnitude of the relationship varies, and other factors are related to poverty and achievement, but the single best predictor of performance is school poverty level. The bright news is that there are schools at all levels that defy the odds. Student achievement is better than predicted in spite of school poverty levels. These schools may provide good models for other schools to emulate. In addition, the evidence from this study indicates that there is more to learn about the performance of some types of school configurations (i.e., K-8 schools) and the performance of non-poverty children in higher poverty schools. Additional numerical data is included in the appendices. [This study was funded by the Maine State Legislature, and the University of Maine System.

Syntax as an exponent of morphological features

In this paper we investigate a selection of issues in the morphology-syntax interface. This has been the locus of intense research activity in recent years particularly within lexicalist theories of grammar such as Lexical Functional Grammar (LFG). A central question addressed in LFG is the way that across languages or within a single language a whole host of morphological, lexical and syntactic means can be deployed to express essentially the same set of meanings or functions. One very specific example of this is seen when very similar (or even identical) grammatical meanings/functions are sometimes expressed by inflected morphological word forms and sometimes by means of syntactic constructions, that is, when a single set of grammatical properties receives synthetic and analytic expression within the same language

Validity and reliability of the Self-Reported Physical Fitness (SRFit) survey

BACKGROUND: An accurate physical fitness survey could be useful in research and clinical care. PURPOSE: To estimate the validity and reliability of a Self-Reported Fitness (SRFit) survey; an instrument that estimates muscular fitness, flexibility, cardiovascular endurance, BMI, and body composition (BC) in adults ≥ 40 years of age. METHODS: 201 participants completed the SF-36 Physical Function Subscale, International Physical Activity Questionnaire (IPAQ), Older Adults' Desire for Physical Competence Scale (Rejeski), the SRFit survey, and the Rikli and Jones Senior Fitness Test. BC, height and weight were measured. SRFit survey items described BC, BMI, and Senior Fitness Test movements. Correlations between the Senior Fitness Test and the SRFit survey assessed concurrent validity. Cronbach's Alpha measured internal consistency within each SRFit domain. SRFit domain scores were compared with SF-36, IPAQ, and Rejeski survey scores to assess construct validity. Intraclass correlations evaluated test-retest reliability. RESULTS: Correlations between SRFit and the Senior Fitness Test domains ranged from 0.35 to 0.79. Cronbach's Alpha scores were .75 to .85. Correlations between SRFit and other survey scores were -0.23 to 0.72 and in the expected direction. Intraclass correlation coefficients were 0.79 to 0.93. All P-values were 0.001. CONCLUSION: Initial evaluation supports the SRFit survey's validity and reliability