Quasi‐trapped ion and electron populations at Mercury

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94682/1/grl28663.pd

Solar parameters for modeling interplanetary background

The goal of the Fully Online Datacenter of Ultraviolet Emissions (FONDUE) Working Team of the International Space Science Institute in Bern, Switzerland, was to establish a common calibration of various UV and EUV heliospheric observations, both spectroscopic and photometric. Realization of this goal required an up-to-date model of spatial distribution of neutral interstellar hydrogen in the heliosphere, and to that end, a credible model of the radiation pressure and ionization processes was needed. This chapter describes the solar factors shaping the distribution of neutral interstellar H in the heliosphere. Presented are the solar Lyman-alpha flux and the solar Lyman-alpha resonant radiation pressure force acting on neutral H atoms in the heliosphere, solar EUV radiation and the photoionization of heliospheric hydrogen, and their evolution in time and the still hypothetical variation with heliolatitude. Further, solar wind and its evolution with solar activity is presented in the context of the charge exchange ionization of heliospheric hydrogen, and in the context of dynamic pressure variations. Also the electron ionization and its variation with time, heliolatitude, and solar distance is presented. After a review of all of those topics, we present an interim model of solar wind and the other solar factors based on up-to-date in situ and remote sensing observations of solar wind. Results of this effort will further be utilised to improve on the model of solar wind evolution, which will be an invaluable asset in all heliospheric measurements, including, among others, the observations of Energetic Neutral Atoms by the Interstellar Boundary Explorer (IBEX).Comment: Chapter 2 in the planned "Cross-Calibration of Past and Present Far UV Spectra of Solar System Objects and the Heliosphere", ISSI Scientific Report No 12, ed. R.M. Bonnet, E. Quemerais, M. Snow, Springe

Estimating Typical Multiple Sclerosis Disability Progression Speed from Clinical Observations

<div><p>Introduction</p><p>Multiple sclerosis (MS) is a chronic disease of the central nervous system. Estimates of MS natural history (NH) disability progression speed from clinical observations vary worldwide. This may reflect, in part, variance in censoring-bias) (missing observations) and assumptions about when irreversible disability progression events occurred. We test whether estimates of progression speed which assume midpoint survival time at irreversible disability endpoints are significantly faster than estimates which assume maximum survival time, and are more stable across study groups and time periods.</p><p>Methods</p><p>Our Nova Scotia NH study population includes 2,240 definite relapsing-onset multiple sclerosis (R-MS) natural history patients with 18,078 Expanded Disability Status Scale (EDSS) clinical observations in study period 1979–2010. Progression speed is measured by rate-of-change in range EDSS 0–6 and by survival time at irreversible endpoints EDSS 1–9. Midpoint censoring-bias-reduction methods are applied to clinical observations.</p><p>Findings</p><p>Typical EDSS increase per year in range EDSS 0–6, assuming midpoint survival time, is estimated to be 0.168 for all R-MS, 0.204 for eventually-DMD-treated patients and 0.155 for never-DMD-treated patients. Estimates assuming midpoint rather than maximum survival time are significantly faster: 16% faster for all R-MS natural history patients, 6% faster for eventually-DMD-treated patients, and 21% faster for never-DMD-treated patients. The variability of estimates across study groups and time periods decreased when midpoint survival time was assumed.</p><p>Conclusions</p><p>Estimates of typical disease progression speed from 1979–2010 Nova Scotia clinical observations are sensitive to censoring-bias and to analysts’ survival time assumptions. Censoring-bias-adjusted estimates of typical natural history disability progression speed in relapsing-onset multiple sclerosis patients are significantly faster, and less variable within and across study groups and time periods, than unadjusted estimates, and are, arguably, more relevant for various stakeholders. The application of censoring-bias-reduction methods to other multiple sclerosis clinical databases may reduce variability in estimates of disability progression speed worldwide.</p></div

Assessment rates for EDSS clinical observations (obs) and expected midpoint observations (Exp), by relapsing-onset MS study groups and study periods, Nova Scotia, 1979–2010.

<p>Footnote: obs = an EDSS clinical observation. obs+Exp = obs and expected EDSS measures, assuming midpoint survival time at irreversible disability endpoints.</p

Kaplan-Meier estimates of natural history survival time at EDSS disability endpoints for 408 eventually-DMD-treated patients, assuming midpoint (top) or maximum (bottom) survival time, Nova Scotia, 1979–2010.

<p>Footnote: The study group is a synthetic onset cohort of 408 definite relapsing-onset multiple sclerosis patients who were eventually treated with disease-modifying-drugs in period 1 August 1998–31 December 2010 and who had an assessed year-of-onset and at least two natural history EDSS clinical observations in period 1979–2010. The top graph shows Kaplan-Meier survival distribution function estimates at irreversible endpoints EDSS 1–9, assuming midpoint survival time (obs+Exp = 3702). The bottom graph shows Kaplan-Meier survival distribution function estimates at irreversible endpoints EDSS 1–9, assuming maximum survival time (obs = 2170). obs = an EDSS clinical observation, including assessed year-of-onset. Exp = an expected EDSS midpoint measure.</p

Irreversible progression paths – assuming maximum, minimum or midpoint survival time.

<p>Footnote: Part (a) shows a hypothetical multiple sclerosis patient’s clinical observations by years since onset. EDSS = Expanded Disability Status Scale. EDSS = 0 at onset is assumed. Of = first clinical observation at an irreversible EDSS endpoint. Or = last repeat clinical observation at an irreversible EDSS endpoint (repeat clinical observations between Of and Or are not shown). Ot = a transitorily high EDSS clinical observation (Ot are not shown in parts (b), (c) and (d)). Max = maximum survival time. Min = minimum survival time. Exp = expected midpoint survival time. <b>bold lines</b> = irreversible disability progression paths.</p