Techniques for measuring arrival times of pulsar signals 1: DSN observations from 1968 to 1980

Techniques used in the ground based observations of pulsars are described, many of them applicable in a navigation scheme. The arrival times of the pulses intercepting Earth are measured at time intervals from a few days to a few months. Low noise, wide band receivers, amplify signals intercepted by 26 m, 34, and 64 m antennas. Digital recordings of total received signal power versus time are cross correlated with the appropriate pulse template

Analysis of Satellite-to-Satellite Tracking (SST) and altimetry data from GEOS-C

Radar altimetry and satellite-to-satellite (SST) range and range rate tracking measurements were used to infer the exterior gravitational field of the earth and the structure of the geoid from GEOS-C metric data. Under the SST analysis, a direct point-by-point estimate of gravity disturbance by means of a recursive filter with backward smoothing was attempted but had to be forsaken because of poor convergence. The adopted representation consists of a more or less uniform grid of discrete masses at a depth of approximately 400 km from the earth's surface. The layer is superimposed on a spherical harmonics model. The procedure for smoothing the altimetry and inferring the fine-structured gravity field over the Atlantic test area is described. The local disturbances are represented by means of a density layer. The altimeter height biases were first estimated by a least squares adjustment at orbital crossover points. After taking out the bias, long wavelength contributions from GEM-6 as well as a calibration correction were subtracted. The residual heights were then represented by a mass distribution beneath the earth's surface

Getting Ready for New Governance Freedoms: A Survey of Further Education College Governance 2012

Further education corporations were formed by the Further and Higher Education Act 1992 and came into being as exempt charities on 1 April 1993. From 1 April 2012 the enactment of the Education Act 2011 provided the governing bodies of further education corporations with a range of structural and procedural choices beyond the prescribed rules and regulations that have been in force for the period 1993-2012. The purpose of this study was to gain an appreciation of the views of clerks to the corporation in anticipation of these new freedoms and to gauge very early responses to them. It aimed to identify potential areas where additional support in terms of training, development and consultancy may be required, for example to make sense of the new freedoms and in understanding the possible implications of any changes made. To this end an e-questionnaire was sent for completion by clerks to the corporation of 332 colleges in England and Wales. The survey was undertaken shortly before the changes came into force and at a time when some important governance material (such as the Financial Memorandum and Audit Code of Practice) had yet to be revised for the new governance operating context. 119 responses were received. This report presents a descriptive overview of those responses. It does not seek to make interpretive judgements, although inferences will be drawn where the data strongly supports it. There are contradictions and inconsistencies in some of the responses which may reflect the fact that only 8 Colleges consider themselves (as perceived by their clerk) ‘well prepared’ for the new governance freedoms. It is therefore reasonable to conclude that assistance in preparation for governance in the context of the new freedoms may be required. Responses indicate most governing bodies will not rush into making changes, although 44 colleges stated that they would wish to take advantage of the new freedoms to make changes to the Instrument and Articles of Government in the next 12 months

Coverage with evidence development: applications and issues

Copyright © Cambridge University Press, 2010OBJECTIVES: The aim of this study was to describe the current issues surrounding Coverage with Evidence Development (CED). CED is characterized by restricted coverage for a new technology in parallel with targeted research when the stated goal of the research or data collection is to provide definitive evidence for the clinical or cost-effectiveness impact of the new technology. METHODS: Presented here is information summarized and interpreted from presentations and discussions at the 2008 Health Technology Assessment International (HTAi) meeting and additional information from the medical literature. This study describes the differences between CED and other conditional coverage agreements, provides a brief history of CED, describes real-world examples of CED, describes the areas of consensus between the stakeholders, discusses the areas for future negotiation between stakeholders, and proposes criteria to assist stakeholders in determining when CED could be appropriate. RESULTS: Payers could interpret the evidence obtained from a CED program either positively or negatively, and a range of possible changes to the reimbursement status of the new technology may result. Striking an appropriate balance between the demands for prompt access to new technology and acknowledging that some degree of uncertainty will always exist is a critical challenge to the uptake of this innovative form of conditional coverage. CONCLUSIONS: When used selectively for innovative procedures, pharmaceuticals, or devices in the appropriate disease areas, CED may provide patients access to promising medicines or technologies while data to minimize uncertainty are collected.The development of the manuscript was funded by Medicines Australi

Time maintenance of user clocks via the tracking and data relay satellite system

A system is described which uses the Tracking and Data Relay Satellite System (TDRSS) itself to compare the user satellite clock with a clock at the White Sands station that is referenced to Universal Time Coordinated (UTC). No command of the spacecraft by the system is required, and actual on-board clock corrections are made by the spacecraft control center at its discretion. Computer models were constructed using basic orbital parameters for user and TDRS satellites. With only first-order corrections and simple averaging techniques for constant clock rates, error measurement precision of better than one microsecond was obtained. More sophisticated computations should allow considerable improvement over this

The Affects of Butyl Acetate and Acetone on Plexiglass

The actions that solvents take on polymers was the focus of the summer 1993 research. There were two goals: one was to measure the distances between the cracks that formed in the plexiglass and two was to determine the time of arrival of the cracks. Two solvents, butyl acetate and acetone were used to generate data on polymethyl methacrylate (PMNA/Plexiglass). The measurement of the time of arrival of a crack was another goal. This quantity is related to the growth of the fractures. This was difficult since only a localized portion of the plexiglass sample could be viewed

The G_2-Hitchin Component of Triangle Groups: Dimension and Integer Points

The image of \PSL(2,\reals) under the irreducible representation into \PSL(7,\reals) is contained in the split real form $G_{2}^{4,3}$ of the exceptional Lie group $G_{2}$. This irreducible representation therefore gives a representation $\rho$ of a hyperbolic triangle group $\Gamma(p,q,r)$ into $G_{2}^{4,3}$, and the \textit{Hitchin component} of the representation variety \Hom(\Gamma(p,q,r),G_{2}^{4,3}) is the component of \Hom(\Gamma(p,q,r),G_{2}^{4,3}) containing $\rho$. This thesis is in two parts: (i) we give a simple, elementary proof of a formula for the dimension of this Hitchin component, this formula having been obtained earlier in [Alessandrini et al.], \citep{Alessandrini2023}, as part of a wider investigation using Higgs bundle techniques, and (ii) we prove the existence of an infinite sequence of integer points on the $G_{2}$-Hitchin component of the (2,4,6)-triangle group. One reason for studying hyperbolic triangle groups is that they contain surface groups as subgroups of finite index. Integer representations in Hitchin components then often provide examples of surface groups represented as elusive \textit{thin matrix groups}, see [Sarnak] \citep{Sarnak2013}, [Long and Reid] \citep{LongReid2013}, and [Kontorovich et al.] \citep{Kontorovich2019}

Effect of a Computer-Based Decision Support Intervention on Autism Spectrum Disorder Screening in Pediatric Primary Care Clinics: A Cluster Randomized Clinical Trial

Importance: Universal early screening for autism spectrum disorder (ASD) is recommended but not routinely performed. Objective: To determine whether computer-automated screening and clinical decision support can improve ASD screening rates in pediatric primary care practices. Design, Setting, and Participants: This cluster randomized clinical trial, conducted between November 16, 2010, and November 21, 2012, compared ASD screening rates among a random sample of 274 children aged 18 to 24 months in urban pediatric clinics of an inner-city county hospital system with or without an ASD screening module built into an existing decision support software system. Statistical analyses were conducted from February 6, 2017, to June 1, 2018. Interventions: Four clinics were matched in pairs based on patient volume and race/ethnicity, then randomized within pairs. Decision support with the Child Health Improvement Through Computer Automation system (CHICA) was integrated with workflow and with the electronic health record in intervention clinics. Main Outcomes and Measures: The main outcome was screening rates among children aged 18 to 24 months. Because the intervention was discontinued among children aged 18 months at the request of the participating clinics, only results for those aged 24 months were collected and analyzed. Rates of positive screening results, clinicians' response rates to screening results in the computer system, and new cases of ASD identified were also measured. Main results were controlled for race/ethnicity and intracluster correlation. Results: Two clinics were randomized to receive the intervention, and 2 served as controls. Records from 274 children (101 girls, 162 boys, and 11 missing information on sex; age range, 23-30 months) were reviewed (138 in the intervention clinics and 136 in the control clinics). Of 263 children, 242 (92.0%) were enrolled in Medicaid, 138 (52.5%) were African American, and 96 (36.5%) were Hispanic. Screening rates in the intervention clinics increased from 0% (95% CI, 0%-5.5%) at baseline to 68.4% (13 of 19) (95% CI, 43.4%-87.4%) in 6 months and to 100% (18 of 18) (95% CI, 81.5%-100%) in 24 months. Control clinics had no significant increase in screening rates (baseline, 7 of 64 children [10.9%]; 6-24 months after the intervention, 11 of 72 children [15.3%]; P = .46). Screening results were positive for 265 of 980 children (27.0%) screened by CHICA during the study period. Among the 265 patients with positive screening results, physicians indicated any response in CHICA in 151 (57.0%). Two children in the intervention group received a new diagnosis of ASD within the time frame of the study. Conclusions and Relevance: The findings suggest that computer automation, when integrated with clinical workflow and the electronic health record, increases screening of children for ASD, but follow-up by physicians is still flawed. Automation of the subsequent workup is still needed