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Search Results: 1 - 10 of 464130 matches for " S. D. Rountree "
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Persistent treatment with cholinesterase inhibitors and/or memantine slows clinical progression of Alzheimer disease
Susan D Rountree, Wenyaw Chan, Valory N Pavlik, Eveleen J Darby, Samina Siddiqui, Rachelle S Doody
Alzheimer's Research & Therapy , 2009, DOI: 10.1186/alzrt7
Abstract: Six hundred forty-one probable AD patients were followed prospectively at an academic center over 20 years. Cumulative drug exposure was expressed as a persistency index (PI) reflecting total years of drug use divided by total years of disease symptoms. Baseline and annual testing consisted of Mini-Mental State Examination (MMSE), Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog), Baylor Profound Mental Status Examination (BPMSE), Clinical Dementia Rating-Sum of Boxes (CDR-SB), Physical Self-Maintenance Scale (PSMS), and Instrumental Activities of Daily Living (IADL). Annual change in slope of neuropsychological and functional tests as predicted by follow-up time, PI, and the interaction of these two variables was evaluated.PI was associated with significantly slower rates of decline (with, without adjustment for covariates) on MMSE (P < 0.0001), PSMS (P < 0.05), IADL (P < 0.0001), and CDR-SB (P < 0.001). There was an insignificant trend (P = 0.053) for the PI to be associated with slower rate of decline on BPMSE. The association of PI with ADAS-Cog followed a quadratic trend (P < 0.01). Analysis including both linear and quadratic terms suggests that PI slowed ADAS-Cog decline temporarily. The magnitude of the favorable effect of a rate change in PI was: MMSE 1 point per year, PSMS 0.4 points per year, IADL 1.4 points per year, and CDR-SB 0.6 points per year. The change in mean test scores is additive over the follow-up period (3 ± 1.94 years).Persistent drug treatment had a positive impact on AD progression assessed by multiple cognitive, functional, and global outcome measures. The magnitude of the treatment effect was clinically significant. Positive treatment effects were even found in those with advanced disease.Since 1993, five drugs have been marketed for the treatment of Alzheimer disease (AD). These treatments are sometimes regarded as having only 'symptomatic' rather than 'disease-modifying' effects, although the utility of this distincti
Factors that influence survival in a probable Alzheimer disease cohort
Susan D Rountree, Wenyaw Chan, Valory N Pavlik, Eveleen J Darby, Rachelle S Doody
Alzheimer's Research & Therapy , 2012, DOI: 10.1186/alzrt119
Abstract: Time to death after symptom onset was determined in 641 probable AD patients who were evaluated annually until death or loss to follow-up, and information was entered into a longitudinal database. Date of death was available for everyone including those eventually lost. Baseline variables included age, sex, race, disease severity, a calculated index of rate of initial cognitive decline from symptom onset to cohort entry (pre-progression rate or PPR), years of education, and medical comorbidities (diabetes, hypertension, hyperlipidemia, coronary disease, cerebrovascular disease). Multivariable Cox proportional hazard regression analysis was used to analyze the baseline and/or time dependent association in Mini-mental Status Exam (MMSE) severity, Physical Self Maintenance Scale (PSMS), Persistency Index (PI) of exposure to antipsychotic and antidementia drugs, and psychotic symptoms (hallucinations, delusions) with mortality.Baseline covariates significantly associated with increased survival were younger age (p = .0016), female sex (p = .0001), and a slower PPR (p < .0001). Overall disease severity at baseline, medical comorbidities, and education did not influence time to death. Time-dependent changes in antipsychotic drug use, development of psychotic symptoms, antidementia drug use, and observed MMSE change were not predictive. In the final model the only time-dependent covariate that significantly decreased survival was worsening of functional ability on the PSMS (hazard ratio = 1.10; CI: 1.07-1.11).In this large AD cohort survival is influenced by age, sex, and the development of functional disability during follow-up. The most important predictor of mortality was a faster rate of cognitive decline at the initial patient visit (PPR). The currently available antidementia drugs do not prolong survival in Alzheimer patients.Life expectancy in people with Alzheimer's disease (AD) is, overall, shorter than what is expected in age-matched, cognitively normal seniors a
LENS as a Probe of Sterile Neutrino Mediated Oscillations
C. Grieb,J. M. Link,M. L. Pitt,R. S. Raghavan,D. Rountree,R. B. Vogelaar
Physics , 2007,
Abstract: Sterile neutrino ($\nu_s$) conversion in meter scale baselines can be sensitively probed using mono-energetic, sub-MeV, flavor pure $\nu_e$'s from an artificial MCi source and the unique technology of the LENS low energy solar $\nu_e$ detector. Active-sterile {\em oscillations} can be directly observed in the granular LENS detector itself to critically test and extend results of short baseline accelerator and reactor experiments.
A search for cosmogenic production of $β$-neutron emitting radionuclides in water
S. Dazeley,M. Askins,M. Bergevin,A. Bernstein,N. S. Bowden,P. Jaffke,S. D. Rountree,T. M. Shokair,M. Sweany
Physics , 2015,
Abstract: Here we present the first results of WATCHBOY, a water Cherenkov detector designed to measure the yield of $\beta$-neutron emitting radionuclides produced by cosmic ray muons in water. In addition to the $\beta$-neutron measurement, we also provide a first look at isolating single-$\beta$ producing radionuclides following showering muons as a check of the detection capabilities of WATCHBOY. The data taken over $207$ live days indicates a $^{9}$Li production yield upper limit of $1.9\times10^{-7}\mu^{-1}g^{-1}\mathrm{cm}^2$ at $\sim400$ meters water equivalent (m.w.e.) overburden at the $90\%$ confidence level. In this work the $^{9}$Li signal in WATCHBOY was used as a proxy for the combined search for $^{9}$Li and $^{8}$He production. This result will provide a constraint on estimates of antineutrino-like backgrounds in future water-based antineutrino detectors.
A Study of the Residual 39Ar Content in Argon from Underground Sources
J. Xu,F. Calaprice,C. Galbiati,A. Goretti,G. Guray,T. Hohman,D. Holtz,A. Ianni,M. Laubenstein,B. Loer,C. Love,C. J. Martoff,D. Montanari,S. Mukhopadhyay,A. Nelson,S. D. Rountree,R. B. Vogelaar,A. Wright
Physics , 2012,
Abstract: The discovery of argon from underground sources with significantly less 39Ar than atmospheric argon was an important step in the development of direct-detection dark matter experiments using argon as the active target. We report on the design and operation of a low background detector with a single phase liquid argon target that was built to study the 39Ar content of the underground argon. Underground argon from the Kinder Morgan CO2 plant in Cortez, Colorado was determined to have less than 0.65% of the 39Ar activity in atmospheric argon.
Nominally brittle cracks in inhomogeneous solids: from microstructural disorder to continuum-level scale
Jonathan Barés,Cindy L. Rountree,Luc Barbier,Daniel Bonamy
Frontiers in Physics , 2014, DOI: 10.3389/fphy.2014.00070
Abstract: We analyze the intermittent dynamics of cracks in heterogeneous brittle materials and the roughness of the resulting fracture surfaces by investigating theoretically and numerically crack propagation in an elastic solid of spatially-distributed toughness. The crack motion splits up into discrete jumps, avalanches, displaying scale-free statistical features characterized by universal exponents. Conversely, the ranges of scales are non-universal and the mean avalanche size and duration depend on the loading microstructure and specimen parameters according to scaling laws which are uncovered. The crack surfaces are found to be logarithmically rough. Their selection by the fracture parameters is formulated in term of scaling laws on the structure functions measured on one-dimensional roughness profiles taken parallel and perpendicular to the direction of crack growth.
Development of an isotropic optical light source for testing nuclear instruments
Zachary W. Yokley,S. Derek Rountree,R. Bruce Vogelaar
Physics , 2015,
Abstract: Nuclear instruments that require precise characterization and calibration of their optical components need well-characterized optical light sources with the desired wavelength, intensity, and directivity. This paper presents a novel technique for determining the performance of optical components by producing an isotropic-like source with a robotically positioned LED. The theory of operation for this light source, results of Monte Carlo validation studies, and experimental results are presented.
A new type of Neutrino Detector for Sterile Neutrino Search at Nuclear Reactors and Nuclear Nonproliferation Applications
C. Lane,S. M. Usman,J. Blackmon,C. Rasco,H. P. Mumm,D. Markoff,G. R. Jocher,R. Dorrill,M. Duvall,J. G. Learned,V. Li,J. Maricic,S. Matsuno,R. Milincic,S. Negrashov,M. Sakai,M. Rosen,G. Varner,P. Huber,M. L. Pitt,S. D. Rountree,R. B. Vogelaar,T. Wright,Z. Yokley
Physics , 2015,
Abstract: We describe a new detector, called NuLat, to study electron anti-neutrinos a few meters from a nuclear reactor, and search for anomalous neutrino oscillations. Such oscillations could be caused by sterile neutrinos, and might explain the "Reactor Antineutrino Anomaly". NuLat, is made possible by a natural synergy between the miniTimeCube and mini-LENS programs described in this paper. It features a "Raghavan Optical Lattice" (ROL) consisting of 3375 boron or $^6$Li loaded plastic scintillator cubical cells 6.3\,cm (2.500") on a side. Cell boundaries have a 0.127\,mm (0.005") air gap, resulting in total internal reflection guiding most of the light down the 3 cardinal directions. The ROL detector technology for NuLat gives excellent spatial and energy resolution and allows for in-depth event topology studies. These features allow us to discern inverse beta decay (IBD) signals and the putative oscillation pattern, even in the presence of other backgrounds. We discuss here test venues, efficiency, sensitivity and project status.
The Physics and Nuclear Nonproliferation Goals of WATCHMAN: A WAter CHerenkov Monitor for ANtineutrinos
M. Askins,M. Bergevin,A. Bernstein,S. Dazeley,S. T. Dye,T. Handler,A. Hatzikoutelis,D. Hellfeld,P. Jaffke,Y. Kamyshkov,B. J. Land,J. G. Learned,P. Marleau,C. Mauger,G. D. Orebi Gann,C. Roecker,S. D. Rountree,T. M. Shokair,M. B. Smy,R. Svoboda,M. Sweany,M. R. Vagins,K. A. van Bibber,R. B. Vogelaar,M. J. Wetstein,M. Yeh
Physics , 2015,
Abstract: This article describes the physics and nonproliferation goals of WATCHMAN, the WAter Cherenkov Monitor for ANtineutrinos. The baseline WATCHMAN design is a kiloton scale gadolinium-doped (Gd) light water Cherenkov detector, placed 13 kilometers from a civil nuclear reactor in the United States. In its first deployment phase, WATCHMAN will be used to remotely detect a change in the operational status of the reactor, providing a first- ever demonstration of the potential of large Gd-doped water detectors for remote reactor monitoring for future international nuclear nonproliferation applications. During its first phase, the detector will provide a critical large-scale test of the ability to tag neutrons and thus distinguish low energy electron neutrinos and antineutrinos. This would make WATCHMAN the only detector capable of providing both direction and flavor identification of supernova neutrinos. It would also be the third largest supernova detector, and the largest underground in the western hemisphere. In a follow-on phase incorporating the IsoDAR neutrino beam, the detector would have world-class sensitivity to sterile neutrino signatures and to non-standard electroweak interactions (NSI). WATCHMAN will also be a major, U.S. based integration platform for a host of technologies relevant for the Long-Baseline Neutrino Facility (LBNF) and other future large detectors. This white paper describes the WATCHMAN conceptual design,and presents the results of detailed simulations of sensitivity for the project's nonproliferation and physics goals. It also describes the advanced technologies to be used in WATCHMAN, including high quantum efficiency photomultipliers, Water-Based Liquid Scintillator (WbLS), picosecond light sensors such as the Large Area Picosecond Photo Detector (LAPPD), and advanced pattern recognition and particle identification methods.
Correction: Predicting progression of Alzheimer's disease
Rachelle S Doody, Valory Pavlik, Paul Massman, Susan Rountree, Eveleen Darby, Wenyaw Chan
Alzheimer's Research & Therapy , 2010, DOI: 10.1186/alzrt38
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