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Search Results: 1 - 10 of 205768 matches for " Mary P. Coffey "
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α-Synuclein and Anti-α-Synuclein Antibodies in Parkinson’s Disease, Atypical Parkinson Syndromes, REM Sleep Behavior Disorder, and Healthy Controls
Lynnae M. Smith, Mya C. Schiess, Mary P. Coffey, Andrea C. Klaver, David A. Loeffler
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0052285
Abstract: α-synuclein is thought to play a key role in Parkinson’s disease (PD) because it is the major protein in Lewy bodies, and because its gene mutations, duplication, and triplication are associated with early-onset PD. There are conflicting reports as to whether serum and plasma concentrations of α-synuclein and anti-α-synuclein antibodies differ between PD and control subjects. The objectives of this study were to compare the levels of α-synuclein and its antibodies between individuals with typical PD (n = 14), atypical Parkinson syndromes (n = 11), idiopathic rapid eye movement sleep behavior disorder (n = 10), and healthy controls (n = 9), to assess the strength of association between these serum proteins, and to determine group sizes needed for a high probability (80% power) of detecting statistical significance for 25% or 50% differences between typical PD and control subjects for these measurements. Analysis of log-transformed data found no statistically significant differences between groups for either α-synuclein or its antibodies. The concentrations of these proteins were weakly correlated (Spearman rho = 0.16). In subjects with typical PD and atypical Parkinson syndromes, anti-α-synuclein antibody levels above 1.5 μg/ml were detected only in subjects with no more than four years of clinical disease. Power analysis indicated that 236 and 73 samples per group would be required for an 80% probability that 25% and 50% differences, respectively, in mean α-synuclein levels between typical PD and control subjects would be statistically significant; for anti-α-synuclein antibodies, 283 and 87 samples per group would be required. Our findings are consistent with those previous studies which suggested that serum concentrations of α-synuclein and its antibodies are not significantly altered in PD.
ELISA measurement of specific non-antigen-bound antibodies to Aβ1-42 monomer and soluble oligomers in sera from Alzheimer's disease, mild cognitively impaired, and noncognitively impaired subjects
Andrea C Klaver, Mary P Coffey, Lynnae M Smith, David A Bennett, John M Finke, Loan Dang, David A Loeffler
Journal of Neuroinflammation , 2011, DOI: 10.1186/1742-2094-8-93
Abstract: Serum antibodies to Aβ1-42 monomer and soluble oligomers in AD, MCI, and NCI subjects (10/group) were measured by ELISA, subtracting polyvalent antibody binding and dissociating antibody-antigen complexes. Differences in mean antibody levels were assessed for significance with repeated measures ANOVA using restricted maximum likelihood estimation, using Tukey-Kramer tests and confidence intervals for multiple comparisons. Spearman's rank correlation was used to determine associations between anti-monomer and anti-oligomer antibody concentrations. Estimated sample sizes required to detect effects of various sizes were calculated.There were no significant differences between groups for mean anti-Aβ antibody levels, although these tended to be higher in AD than NCI specimens. Estimated group sizes of 328 and 150 for anti-Aβ monomer and oligomer antibodies, respectively, would have been required for 80% power for significance at 0.05 for a 25% increase in the AD mean relative to the NCI mean. Serum antibody concentrations to Aβ monomer and oligomers were strongly associated (correlations: 0.798 for undissociated sera, 0.564 for dissociated sera). Antibody-antigen dissociation significantly increased anti-Aβ monomer but not anti-Aβ oligomer antibody levels.The findings in this pilot study are consistent with relatively similar concentrations of specific, non-antigen-bound antibodies to Aβ1-42 monomer and soluble oligomers in AD, MCI, and NCI sera. The differences between groups for these antibodies would have required approximate group sizes of 328 and 150, respectively, for a high probability for statistical significance. These findings do not support the hypothesis that reduced levels of anti-Aβ antibodies might contribute to AD's pathogenesis.Amyloid-beta (Aβ), the major plaque-associated protein in the Alzheimer's disease (AD) brain, has become the main target for AD therapy since the formulation of the "amyloid hypothesis" [1]. The significance of serum antibodies t
Direct aperture optimization as a means of reducing the complexity of intensity modulated radiation therapy plans
Maria Broderick, Michelle Leech, Mary Coffey
Radiation Oncology , 2009, DOI: 10.1186/1748-717x-4-8
Abstract: One of the main problems of IMRT, which becomes even more apparent as the complexity of the IMRT plan increases, is the dramatic increase in the number of Monitor Units (MU) required to deliver a fractionated treatment. The difficulty with this increase in MU is its association with increased treatment times and a greater leakage of radiation from the MLCs increasing the total body dose and the risk of secondary cancers in patients. Therefore one attempts to find ways of reducing these MU without compromising plan quality.The design of inverse planning systems where the beam is divided into small beamlets to produce the required intensity map automatically introduces complexity into IMRT treatment planning. Plan complexity is associated with many negative factors such as dosimetric uncertainty and delivery issues A large search space is required necessitating much computing power. However, the limitations of the delivery technology are not taken into consideration when designing the ideal intensity map therefore a further step termed the sequencing step is required to convert the ideal intensity map into a deliverable one.Many approaches have been taken to reduce the complexity. These include setting intensity limits, putting penalties on the cost function and using smoothing filters Direct Aperture optimization (DAO) incorporates the limitations of the delivery technology at the initial design of the intensity map thereby eliminating the sequencing step. It also gives control over the number of segments and hence control over the complexity of the plan although the design of the segments is independent of the person preparing the plan.Intensity Modulated Radiation Therapy (IMRT) is an advanced form of 3D radiotherapy. The non-intuitive nature of IMRT planning can sometimes lead to very complex plans. This review highlights the difficulties of overly complex plans and evaluates Direct Aperture Optimization (DAO) as a potential means of reducing this complexity.Inten
"The Art of Motorcycle (Image) Maintenance"
Mary K. Coffey,Jeremy S. Packer
International Journal of Motorcycle Studies , 2007,
Magnetic Anisotropy in the Molecular Complex V15
N. P. Konstantinidis,D. Coffey
Physics , 2002, DOI: 10.1103/PhysRevB.66.174426
Abstract: We apply degenerate perturbation theory to investigate the effects of magnetic anisotropy in the magnetic molecule V15. Magnetic anisotropy is introduced via Dzyaloshinskii-Moriya (DM) interaction in the full Hilbert space of the system. Our model provides an explanation for the rounding of transitions in the magnetization as a function of applied field at low temperature, from which an estimate for the DM interaction is found. We find that the calculated energy differences of the lowest energy states are consistent with the available data. Our model also offers a novel explanation for the hysteretic nature of the time-dependent magnetization data.
Accurate Results from Perturbation Theory for Strongly Frustrated $S=1/2$ Heisenberg Spin Clusters
N. P. Konstantinidis,D. Coffey
Physics , 2000, DOI: 10.1103/PhysRevB.63.184436
Abstract: We investigate the use of perturbation theory in finite sized frustrated spin systems by calculating the effect of quantum fluctuations on coherent states derived from the classical ground state. We first calculate the ground and first excited state wavefunctions as a function of applied field for a 12-site system and compare with the results of exact diagonalization. We then apply the technique to a 20-site system with the same three fold site coordination as the 12-site system. Frustration results in asymptotically convergent series for both systems which are summed with Pad\'e approximants. We find that at zero magnetic field the different connectivity of the two systems leads to a triplet first excited state in the 12-site system and a singlet first excited state in the 20-site system, while the ground state is a singlet for both. We also show how the analytic structure of the Pad\'e approximants at $|\lambda| \simeq 1$ evolves in the complex $\lambda$ plane at the values of the applied field where the ground state switches between spin sectors and how this is connected with the non-trivial dependence of the $$ number on the strength of quantum fluctuations. We discuss the origin of this difference in the energy spectra and in the analytic structures. We also characterize the ground and first excited states according to the values of the various spin correlation functions.
Assessment of an Interactive Internet Program to Educate Children Aged 7 - 9 about Science, the Brain and Drugs  [PDF]
Mary P. Metcalf
Creative Education (CE) , 2013, DOI: 10.4236/ce.2013.411097
Abstract: BrainTrain4Kids.com is an interactive science Internet program for children aged 7 - 9 developed with funding from the National Institute on Drug Abuse (NIDA). Based on NIDA’s classroom curriculum, Brain Power!, we adapted and expanded this material to optimize online media. The primary objective of the curriculum is to provide an early foundation for drug abuse prevention efforts by educating elementary school-aged children about the brain and how alcohol, tobacco, and drugs can harm it. Secondary aims include improving knowledge, appreciation for scientific inquiry, and improving/sustaining a positive attitude towards science. The program employs engaging and entertaining elements including Flashbased activities and educational games. Assessment of the program occurred using a two-group, randomized case/control pre/post trial with a crossover design using a convenience sample. Child participants (N = 102) from control and case groups had similar knowledge and attitudes towards science at baseline. At post-intervention, there was a significant increase in knowledge scores for the case group; this increase was retained at the six-week follow-up. Case group attitudes towards science were more positive immediately after post-intervention than at baseline, and at follow up than at baseline. BrainTrain4Kids can be an effective tool for educating children about science and drugs, and has the potential to positively impact attitudes. It can be used as a part of a drug abuse prevention program either in schools or at home.
Thermal fluctuations of magnetic nanoparticles
William T. Coffey,Yuri P. Kalmykov
Physics , 2012, DOI: 10.1063/1.4754272
Abstract: The reversal time (superparamagnetic relaxation time) of the magnetization of fine single domain ferromagnetic nanoparticles owing to thermal fluctuations plays a fundamental role in information storage, paleomagnetism, biotechnology, etc. Here a comprehensive tutorial-style review of the achievements of fifty years of development and generalizations of the seminal work of Brown [W.F. Brown, Jr., Phys. Rev., 130, 1677 (1963)] on thermal fluctuations of magnetic nanoparticles is presented. Analytical as well as numerical approaches to the estimation of the damping and temperature dependence of the reversal time based on Brown's Fokker-Planck equation for the evolution of the magnetic moment orientations on the surface of the unit sphere are critically discussed while the most promising directions for future research are emphasized.
Improved Dynamic Response of DC to DC Converter Using Hybrid PSO Tuned Fuzzy Sliding Mode Controller  [PDF]
R. Anand, P. Melba Mary
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.76080
Abstract: DC/DC switching converters are widely used in numerous appliances in modern existence. In this paper, the dynamic and transient response of phase shift series resonant DC/DC converter are improved using hybrid particle swarm optimization tuned fuzzy sliding mode controller under starting and load step change conditions. The aim of the control is to regulate the output voltage beneath the load change. The model of the hybrid particle swarm optimization tuned fuzzy sliding mode controller is implemented using Sim Power Systems toolbox of MATLAB SIMULINK. Performance of the proposed dynamic novel control under step load change condition is investigated.
Design of Robust Controller for LFC of Interconnected Power System Considering Communication Delays  [PDF]
T. Jesintha Mary, P. Rangarajan
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.76068
Abstract: The usage of open communication infrastructure for transmitting the control signals in the Load Frequency Control (LFC) scheme of power system introduces time delays. These time delays may degrade the dynamic performance of the power system. This paper proposes a robust method to design a controller for multi-area LFC schemes considering communication delays. In existing literature, the controller values of LFC are designed using time domain approach which is less accurate than the proposed method. In proposed method, the controller values are determined by moving the rightmosteigenvalues of the system to the left half plane in a quasi-continuous way for a preset upper bound of time delay. Then the robustness of the proposed controller is assessed by estimating the maximumtolerable value of time delay for maintaining system stability. Simulation studies are carried out for multi-area LFC scheme equipped with the proposed controller
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