Multistep integration formulas for the numerical integration of the satellite problem

The use of two Class 2/fixed mesh/fixed order/multistep integration packages of the PECE type for the numerical integration of the second order, nonlinear, ordinary differential equation of the satellite orbit problem. These two methods are referred to as the general and the second sum formulations. The derivation of the basic equations which characterize each formulation and the role of the basic equations in the PECE algorithm are discussed. Possible starting procedures are examined which may be used to supply the initial set of values required by the fixed mesh/multistep integrators. The results of the general and second sum integrators are compared to the results of various fixed step and variable step integrators

Single Spin Asymmetry at Large x_F and k_T

The large single spin asymmetries observed at high momentum fractions x_F and transverse momenta k_T in p^\uparrow p -> \pi(x_F,k_T)+X as well as in pp -> \Lambda^\uparrow(x_F,k_T)+X suggest that soft helicity flip processes are coherent with hard scattering. Such coherence can be maintained if x_F -> 1 as k_T -> \infty, while k_T^2(1-x_F) \sim \Lambda_QCD^2 stays fixed. The entire hadron wave function, rather than a single quark, then contributes to the scattering process. Analogous coherence effects have been seen experimentally in the Drell-Yan process at high x_F. We find that the p^\uparrow p -> \pi(x_F,k_T)+X production amplitudes have large dynamic phases and that helicity flip contributions are unsuppressed in this limit, giving rise to potentially large single spin asymmetries.Comment: 11 pages, 2 figures. v2: References and a preprint number added. Calculation of section 4 modified. v3: Minor changes in text. Version to be published in JHE

Studies of an orbital gradiometer mission

The goal of using an orbital gradiometer mission to provide an accurate (1 to 2 mgal), high resolution (1 by 1 deg), global map of the earth's geopotential is currently being investigated. This investigation involves the simulation of the satellite ephemeris and the corresponding gradiometer measurements which can be used in the study of various techniques and methodologies that were proposed to recover the parameters used in modeling the geopotential. Also, the effects on the mission of various time varying forces acting on the spacecraft were included in the studies

Multiplier-continuation algorthms for constrained optimization

Several path following algorithms based on the combination of three smooth penalty functions, the quadratic penalty for equality constraints and the quadratic loss and log barrier for inequality constraints, their modern counterparts, augmented Lagrangian or multiplier methods, sequential quadratic programming, and predictor-corrector continuation are described. In the first phase of this methodology, one minimizes the unconstrained or linearly constrained penalty function or augmented Lagrangian. A homotopy path generated from the functions is then followed to optimality using efficient predictor-corrector continuation methods. The continuation steps are asymptotic to those taken by sequential quadratic programming which can be used in the final steps. Numerical test results show the method to be efficient, robust, and a competitive alternative to sequential quadratic programming

The Role of Attorney Fee Shifting in Public Interest Litigation

BACKGROUND: Brain tissue segmentation of white matter (WM), grey matter (GM), and cerebrospinal fluid (CSF) are important in neuroradiological applications. Quantitative Mri (qMRI) allows segmentation based on physical tissue properties, and the dependencies on MR scanner settings are removed. Brain tissue groups into clusters in the three dimensional space formed by the qMRI parameters R1, R2 and PD, and partial volume voxels are intermediate in this space. The qMRI parameters, however, depend on the main magnetic field strength. Therefore, longitudinal studies can be seriously limited by system upgrades. The aim of this work was to apply one recently described brain tissue segmentation method, based on qMRI, at both 1.5 T and 3.0 T field strengths, and to investigate similarities and differences. METHODS: In vivo qMRI measurements were performed on 10 healthy subjects using both 1.5 T and 3.0 T MR scanners. The brain tissue segmentation method was applied for both 1.5 T and 3.0 T and volumes of WM, GM, CSF and brain parenchymal fraction (BPF) were calculated on both field strengths. Repeatability was calculated for each scanner and a General Linear Model was used to examine the effect of field strength. Voxel-wise t-tests were also performed to evaluate regional differences. RESULTS: Statistically significant differences were found between 1.5 T and 3.0 T for WM, GM, CSF and BPF (p<0.001). Analyses of main effects showed that WM was underestimated, while GM and CSF were overestimated on 1.5 T compared to 3.0 T. The mean differences between 1.5 T and 3.0 T were -66 mL WM, 40 mL GM, 29 mL CSF and -1.99% BPF. Voxel-wise t-tests revealed regional differences of WM and GM in deep brain structures, cerebellum and brain stem. CONCLUSIONS: Most of the brain was identically classified at the two field strengths, although some regional differences were observed

Application of Consider Covariance to the Extended Kalman Filter

The extended Kalman filter (EKF) is the basis for many applications of filtering theory to real-time problems where estimates of the state of a dynamical system are to be computed based upon some set of observations. The form of the EKF may vary somewhat from one application to another, but the fundamental principles are typically unchanged among these various applications. As is the case in many filtering applications, models of the dynamical system (differential equations describing the state variables) and models of the relationship between the observations and the state variables are created. These models typically employ a set of constants whose values are established my means of theory or experimental procedure. Since the estimates of the state are formed assuming that the models are perfect, any modeling errors will affect the accuracy of the computed estimates. Note that the modeling errors may be errors of commission (errors in terms included in the model) or omission (errors in terms excluded from the model). Consequently, it becomes imperative when evaluating the performance of real-time filters to evaluate the effect of modeling errors on the estimates of the state

Evaluation of GPS Coverage for the X-33 Michael-6 Trajectory

The onboard navigational system for the X-33 test flights will be based on the use of measurements collected from the Embedded Global Positioning System (GPS)/INS system. Some of the factors which will affect the quality of the GPS contribution to the navigational solution will be the number of pseudorange measurements collected at any instant in time, the distribution of the GPS satellites within the field of view, and the inherent noise level of the GPS receiver. The distribution of GPS satellites within the field of view of the receiver's antenna will depend on the receiver's position, the time of day, pointing direction of the antenna, and the effective cone angle of the antenna. The number of pseudorange measurements collected will depend upon these factors as well as the time required to lock onto a GPS satellite signal once the GPS satellite comes into the field of view of the antenna and the number of available receiver channels. The objective of this study is to evaluate the GPS coverage resulting from the proposed antenna pointing directions, the proposed antenna cone angles, and the effects due to the time of day for the X-33 Michael-6 trajectory from launch at Edwards AFB, California, to the start of the Terminal Area Energy Management (TAEM) phase on approach to Michael AAF, Utah

Clostridium difficile cytotoxin B in adults with diarrhea: a comparison of patients treated or not treated with antibiotics prior to infection

AbstractDepartments of Medicine and Immunology Microbiology, Pathology and Infectious Diseases, Karolinska Institute, Huddinge University Hospital, Huddinge, SwedenObjectiveTo study the detection rate of Clostridium difficile cytotoxin B in stool specimens from adults with diarrhea as related to previous antimicrobial treatment.MethodsStool specimens from 802 adult patients with diarrhea and 203 healthy controls were tested for C. dificile cytotoxin B using a cell cytotoxicity assay. Antibiotic susceptibility testing of C. difficile was performed with the E test.ResultsOf 173 patients treated with antimicrobial medication within 5 weeks of onset of diarrhea, 60 (35%) were positive for C. difficile cytotoxin B (group A) compared to only 41 (7%) of 629 untreated patients (group B) and two of the 203 (1%) healthy controls. Compared to patients in group A, patients in group B possessed characteristics not usually connected with C. difficile disease. They were generally younger (median age 40 years vs. 73 years), had been hospitalized less frequently (10% vs. 67%), had more often travelled abroad within the previous 2 weeks (46% vs. 1%), and more often had multiple enteropathogens (41% vs. 3%). Minimal inhibitory concentrations for vancomycin, metronidazole and fucidic acid to C. difficile isolates ranged from 0.5 to 4 mg/L, from 0.125 to 256 mg/L and 0.25 to 4 mg/L, respectively.ConclusionsThe detection rate of C. difficile cytotoxin B in patients with diarrhea, not associated with antibiotic treatment, is comparable to that in healthy control subjects. It probably merely reflects a carrier state without clinical significance

“It’s Part of My Responsibility to Help”: Developing a Measure of Motivations for Extrinsic Emotion Regulation

Introduction A growing field of research has emerged to examine the processes by which people manage their own emotions as well as the emotions of others during social interactions, a set of phenomena broadly known as interpersonal emotion regulation (IER). Within this broad category, extrinsic emotion regulation (EER) refers specifically to the processes by which an individual targets and attempts to regulate the emotions of others (Zaki & Williams, 2013). Recent work by Netzer et al. (2015) has explored the emotion-related goals people have when engaging in EER, suggesting that both hedonic and instrumental goals may motivate these regulation attempts. We know that people can employ a variety of motives during EER attempts. But, which ones do they actually use in practice? And, how can we measure individual differences in one’s EER motivational tendencies? The current study aims to develop a better understanding of the answers to these questions through thematic analyses of participant narratives