Ion Chamber Collection Efficiencies for Proton Spot Scanning Calibration

Charge accumulation was measured under calibration conditions in the spread-out Bragg peak (SOBP) using the calibration bias as well as a range of voltages from 10V to 500V and a Farmer-style ion chamber. Collection efficiency was determined by extrapolating to infinite voltage. Similar measurements were taken in an identical dose distribution with a much shorter spot duration. The impact of each of the three models on calibration was then quantified using the TRS-398 protocol. The collection efficiency for the standard calibration was determined to agree well with the prediction of a continuous beam recombination correction. The standard calibration field was found to persistently agree with a continuous beam recombination correction for much lower operating biases. The collection efficiency result for the short spot duration field did not agree with either the continuous or pulsed-beam correction. Using the incorrect recombination model under the standard calibration conditions resulted in a 0.5% calibration difference. We have determined that our spot scanning system would be most appropriately calibrated using a recombination correction with continuous beam model. Physicists responsible for the calibration of such systems are advised to take measurements described here to correctly identify the applicable recombination model for their clinics.Comment: Submitted December 16, 2015 to Medical Physic

An empirical test for cellular automaton models of traffic flow

Based on a detailed microscopic test scenario motivated by recent empirical studies of single-vehicle data, several cellular automaton models for traffic flow are compared. We find three levels of agreement with the empirical data: 1) models that do not reproduce even qualitatively the most important empirical observations, 2) models that are on a macroscopic level in reasonable agreement with the empirics, and 3) models that reproduce the empirical data on a microscopic level as well. Our results are not only relevant for applications, but also shed new light on the relevant interactions in traffic flow.Comment: 28 pages, 36 figures, accepted for publication in PR

Assessment of potential cardiotoxic side effects of mitoxantrone in patients with multiple sclerosis

Previous studies showed that mitoxantrone can reduce disability progression in patients with multiple sclerosis (MS). There is, however, concern that it may cause irreversible cardiomyopathy with reduced left ventricular (LV) ejection fraction (EF) and congestive heart failure. The aim of this prospective study was to investigate cardiac side effects of mitoxantrone by repetitive cardiac monitoring in MS patients. The treatment protocol called for ten courses of a combined mitoxantrone (10 mg/m(2) body surface) and methylprednisolone therapy. Before each course, a transthoracic echocardiogram was performed to determine the LV end-diastolic diameter, the end-systolic diameter and the fractional shortening; the LV-EF was calculated. Seventy-three patients participated (32 males; age 48 +/- 12 years, range 20-75 years; 25 with primary progressive, 47 with secondary progressive and 1 with relapsing-remitting MS) who received at least four courses of mitoxantrone. Three of the 73 patients were excluded during the study (2 patients discontinued therapy; 1 patient with a previous history of ischemic heart disease developed atrial fibrillation after the second course of mitoxantrone). The mean cumulative dose of mitoxantrone was 114.0 +/- 33.8 mg. The mean follow-up time was 23.4 months (range 10-57 months). So far, there has been no significant change in any of the determined parameters (end-diastolic diameter, end-systolic diameter, fractional shortening, EF) over time during all follow-up investigations. Mitoxantrone did not cause signs of congestive heart failure in any of the patients. Further cardiac monitoring is, however, needed to determine the safety of mitoxantrone after longer follow-up times and at higher cumulative doses. Copyright (C) 2005 S. Karger AG, Basel

Intrinsic Absorption in the Spectrum of Mrk 279: Simultaneous Chandra, FUSE, and STIS Observations

We present a study of the intrinsic X-ray and far-ultraviolet absorption in the Seyfert 1.5 galaxy Markarian 279 using simultaneous observations from the Chandra X-ray Observatory, the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope, and the Far Ultraviolet Spectroscopic Explorer (FUSE). We also present FUSE observations made at three additional epochs. We detect the Fe K-alpha emission line in the Chandra spectrum, and its flux is consistent with the low X-ray continuum flux level of Mrk 279 at the time of the observation. Due to low signal-to-noise ratios in the Chandra spectrum, no O VII or O VIII absorption features are observable in the Chandra data, but the UV spectra reveal strong and complex absorption from HI and high-ionization species such as O VI, N V, and C IV, as well as from low-ionization species such as C III, N III, C II, and N II in some velocity components. The far-UV spectral coverage of the FUSE data provides information on high-order Lyman series absorption, which we use to calculate the optical depths and line and continuum covering fractions in the intrinsic HI absorbing gas in a self-consistent fashion. The UV continuum flux of Mrk 279 decreases by a factor of ~7.5 over the time spanning these observations and we discuss the implications of the response of the absorption features to this change. From arguments based on the velocities, profile shapes, covering fractions and variability of the UV absorption, we conclude that some of the absorption components, particularly those showing prominent low-ionization lines, are likely associated with the host galaxy of Mrk 279, and possibly with its interaction with a close companion galaxy, while the remainder arises in a nuclear outflow.Comment: To appear in 2004 May ApJS; double-column format; 58 pages, incl. 29 figures, 9 tables; minor changes to tex

A controlled trial of value-based insurance design – The MHealthy: Focus on Diabetes (FOD) trial

<p>Abstract</p> <p>Background</p> <p>Diabetes affects over 20 million Americans, resulting in substantial morbidity, mortality, and costs. While medications are the cornerstone of secondary prevention, many evidence-based therapies are underutilized, and patients often cite out-of-pocket costs as the reason. Value-based insurance design (VBID) is a 'clinically sensitive' refinement to benefit design which links patient cost-sharing to therapy value; the more clinically beneficial (and valuable) a therapy is for a patient, the lower that patient's cost-sharing should be. We describe the design and implementation of MHealthy: Focus on Diabetes (FOD), a prospective, controlled trial of targeted co-payment reductions for high value, underutilized therapies for individuals with diabetes.</p> <p>Methods</p> <p>The FOD trial includes 2,507 employees and dependents with diabetes insured by one large employer. Approximately 81% are enrolled in a single independent-practice association model health maintenance organization. The control group includes 8,637 patients with diabetes covered by other employers and enrolled in the same managed care organization. Both groups received written materials about the importance of adherence to secondary prevention therapies, while only the intervention group received targeted co-payment reductions for glycemic agents, antihypertensives, lipid-lowering agents, antidepressants, and diabetic eye exams. Primary outcomes include medication uptake and adherence. Secondary outcomes include health care utilization and expenditures. An interrupted time series, control group design will allow rigorous assessment of the intervention's impact, while controlling for unrelated temporal trends. Individual patient-level baseline data are presented.</p> <p>Discussion</p> <p>To our knowledge, this is the first prospective controlled trial of co-payment reductions targeted to high-value services for high-risk patients. It will provide important information on feasibility of implementation and effectiveness of VBID in a real-world setting. This program has the potential for broad dissemination to other employers and insurers wishing to improve the value of their health care spending.</p

An Improved Implementation and Abstract Interface for Hybrid

Hybrid is a formal theory implemented in Isabelle/HOL that provides an interface for representing and reasoning about object languages using higher-order abstract syntax (HOAS). This interface is built around an HOAS variable-binding operator that is constructed definitionally from a de Bruijn index representation. In this paper we make a variety of improvements to Hybrid, culminating in an abstract interface that on one hand makes Hybrid a more mathematically satisfactory theory, and on the other hand has important practical benefits. We start with a modification of Hybrid's type of terms that better hides its implementation in terms of de Bruijn indices, by excluding at the type level terms with dangling indices. We present an improved set of definitions, and a series of new lemmas that provide a complete characterization of Hybrid's primitives in terms of properties stated at the HOAS level. Benefits of this new package include a new proof of adequacy and improvements to reasoning about object logics. Such proofs are carried out at the higher level with no involvement of the lower level de Bruijn syntax.Comment: In Proceedings LFMTP 2011, arXiv:1110.668

A review of paratuberculosis in dairy herds — Part 1: Epidemiology

Bovine paratuberculosis is a chronic infectious disease of cattle caused by Mycobacterium avium subspecies paratuberculosis (MAP). This is the first in a two-part review of the epidemiology and control of paratuberculosis in dairy herds. Paratuberculosis was originally described in 1895 and is now considered endemic among farmed cattle worldwide. MAP has been isolated from a wide range of non-ruminant wildlife as well as humans and non-human primates. In dairy herds, MAP is assumed to be introduced predominantly through the purchase of infected stock with additional factors modulating the risk of persistence or fade-out once an infected animal is introduced. Faecal shedding may vary widely between individuals and recent modelling work has shed some light on the role of super-shedding animals in the transmission of MAP within herds. Recent experimental work has revisited many of the assumptions around age susceptibility, faecal shedding in calves and calf-to-calf transmission. Further efforts to elucidate the relative contributions of different transmission routes to the dissemination of infection in endemic herds will aid in the prioritisation of efforts for control on farm

A review of paratuberculosis in dairy herds — Part 2: On-farm control

Bovine paratuberculosis is a chronic infectious disease of cattle, caused by Mycobacterium avium subspecies paratuberculosis (MAP). This is the second in a two-part review of the epidemiology and control of paratuberculosis in dairy herds. Several negative production effects associated with MAP infection have been described, but perhaps the most significant concern in relation to the importance of paratuberculosis as a disease of dairy cattle is the potential link with Crohn’s disease in humans. Milk is considered a potential transmission route to humans and it is recognised that pasteurisation does not necessarily eliminate the bacterium. Therefore, control must also include reduction of the levels of MAP in bulk milk supplied from dairy farms. There is little field evidence in support of specific control measures, although several studies seem to show a decreased prevalence associated with the implementation of a combined management and test-and-cull programme. Improvements in vaccination efficacy and reduced tuberculosis (TB) test interference may increase uptake of vaccination as a control option. Farmer adoption of best practice recommendations at farm level for the control of endemic diseases can be challenging. Improved understanding of farmer behaviour and decision making will help in developing improved communication strategies which may be more efficacious in affecting behavioural change on farm