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Search Results: 1 - 10 of 409434 matches for " M Patricia;Carlson "
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Cuticular hydrocarbons of Chagas disease vectors in Mexico
Juárez, M Patricia;Carlson, David A;Salazar Schettino, Paz María;Mijailovsky, Sergio;Rojas, Gloria;
Memórias do Instituto Oswaldo Cruz , 2002, DOI: 10.1590/S0074-02762002000600012
Abstract: capillary gas-liquid chromatography was used to analyse the cuticular hydrocarbons of three triatomine species, triatoma dimidiata, t. barberi and dipetalogaster maxima, domestic vectors of chagas disease in mexico. mixtures of saturated hydrocarbons of straight and methyl-branched chains were characteristic of the three species, but quantitatively different. major methylbranched components mostly corresponded to different saturated isomers of monomethyl, dimethyl and trimethyl branched hydrocarbons ranging from 29 to 39 carbon backbones. sex-dependant, quantitative differences in certain hydrocarbons were apparent in t. dimidiata.
Cuticular hydrocarbons of Chagas disease vectors in Mexico
Juárez M Patricia,Carlson David A,Salazar Schettino Paz María,Mijailovsky Sergio
Memórias do Instituto Oswaldo Cruz , 2002,
Abstract: Capillary gas-liquid chromatography was used to analyse the cuticular hydrocarbons of three triatomine species, Triatoma dimidiata, T. barberi and Dipetalogaster maxima, domestic vectors of Chagas disease in Mexico. Mixtures of saturated hydrocarbons of straight and methyl-branched chains were characteristic of the three species, but quantitatively different. Major methylbranched components mostly corresponded to different saturated isomers of monomethyl, dimethyl and trimethyl branched hydrocarbons ranging from 29 to 39 carbon backbones. Sex-dependant, quantitative differences in certain hydrocarbons were apparent in T. dimidiata.
Technical Note: Assay of cell quantity in the fibroblast-populated collagen matrix with a tetrazolium reagent
M A Carlson
European Cells and Materials (ECM) , 2006,
Abstract: Determination of cell quantity in three-dimensional culture systems, such as the fibroblast-populated collagen matrix, can be difficult secondary to the abundance of extracellular collagen. The WST-1 assay, which can quantitate cellular processes in monolayer culture, was tested as a measure of relative cell quantity in a three dimensional culture system, the fibroblast-populated collagen matrix. The assay had acceptable accuracy and precision, and was not affected by the extracellular matrix. It was concluded that the assay was a reasonable alternative to other measures of cell quantity in the fibroblast-populated collagen matrix.
Empirical transverse charge densities in the nucleon and the nucleon-to-$\Delta$ transition
Carlson, C. E.;Vanderhaeghen, M.
High Energy Physics - Phenomenology , 2007, DOI: 10.1103/PhysRevLett.100.032004
Abstract: Using only the current empirical information on the nucleon electromagnetic form factors we map out the transverse charge density in proton and neutron as viewed from a light front moving towards a transversely polarized nucleon. These charge densities are characterized by a dipole pattern, in addition to the monopole field corresponding with the unpolarized density. Furthermore, we use the latest empirical information on the $N \to \Delta$ transition form factors to map out the transition charge density which induces the $N \to \Delta$ excitation. This transition charge density in a transversely polarized $N$ and $\Delta$ contains both monopole, dipole and quadrupole patterns, the latter corresponding with a deformation of the hadron's charge distribution.
Force networks and the dynamic approach to jamming in sheared granular media
Gregg Lois,Jean M. Carlson
Physics , 2006, DOI: 10.1209/0295-5075/80/58001
Abstract: Diverging correlation lengths on either side of the jamming transition are used to formulate a rheological model of granular shear flow, based on the propagation of stress through force chain networks. The model predicts three distinct flow regimes, characterized by the shear rate dependence of the stress tensor, that have been observed in both simulations and experiments. The boundaries separating the flow regimes are quantitatively determined and testable. In the limit of jammed granular solids, the model predicts the observed anomalous scaling of the shear modulus and a new relation for the shear strain at yield.
Highly Optimized Tolerance: Robustness and Power Laws in Complex Systems
J. M. Carlson,John Doyle
Physics , 1998, DOI: 10.1103/PhysRevE.60.1412
Abstract: We introduce highly optimized tolerance (HOT), a mechanism that connects evolving structure and power laws in interconnected systems. HOT systems arise, e.g., in biology and engineering, where design and evolution create complex systems sharing common features, including (1) high efficiency, performance, and robustness to designed-for uncertainties, (2) hypersensitivity to design flaws and unanticipated perturbations, (3) nongeneric, specialized, structured configurations, and (4) power laws. We introduce HOT states in the context of percolation, and contrast properties of the high density HOT states with random configurations near the critical point. While both cases exhibit power laws, only HOT states display properties (1-3) associated with design and evolution.
ISway: a sensitive, valid and reliable measure of postural control
Mancini Martina,Salarian Arash,Carlson-Kuhta Patricia,Zampieri Cris
Journal of NeuroEngineering and Rehabilitation , 2012, DOI: 10.1186/1743-0003-9-59
Abstract: Background Clinicians need a practical, objective test of postural control that is sensitive to mild neurological disease, shows experimental and clinical validity, and has good test-retest reliability. We developed an instrumented test of postural sway (ISway) using a body-worn accelerometer to offer an objective and practical measure of postural control. Methods We conducted two separate studies with two groups of subjects. Study I: sensitivity and experimental concurrent validity. Thirteen subjects with early, untreated Parkinson’s disease (PD) and 12 age-matched control subjects (CTR) were tested in the laboratory, to compare sway from force-plate COP and inertial sensors. Study II: test-retest reliability and clinical concurrent validity. A different set of 17 early-to-moderate, treated PD (tested ON medication), and 17 age-matched CTR subjects were tested in the clinic to compare clinical balance tests with sway from inertial sensors. For reliability, the sensor was removed, subjects rested for 30 min, and the protocol was repeated. Thirteen sway measures (7 time-domain, 5 frequency-domain measures, and JERK) were computed from the 2D time series acceleration (ACC) data to determine the best metrics for a clinical balance test. Results Both center of pressure (COP) and ACC measures differentiated sway between CTR and untreated PD. JERK and time-domain measures showed the best test-retest reliability (JERK ICC was 0.86 in PD and 0.87 in CTR; time-domain measures ICC ranged from 0.55 to 0.84 in PD and from 0.60 to 0.89 in CTR). JERK, all but one time-domain measure, and one frequency measure were significantly correlated with the clinical postural stability score (r ranged from 0.50 to 0.63, 0.01 < p < 0.05). Conclusions Based on these results, we recommend a subset of the most sensitive, reliable, and valid ISway measures to characterize posture control in PD: 1) JERK, 2) RMS amplitude and mean velocity from the time-domain measures, and 3) centroidal frequency as the best frequency measure, as valid and reliable measures of balance control from ISway.
Highly optimized tolerance and power laws in dense and sparse resource regimes
M. Manning,J. M. Carlson,J. Doyle
Physics , 2005, DOI: 10.1103/PhysRevE.72.016108
Abstract: Power law cumulative frequency $(P)$ vs. event size $(l)$ distributions $P(\geq l)\sim l^{-\alpha}$ are frequently cited as evidence for complexity and serve as a starting point for linking theoretical models and mechanisms with observed data. Systems exhibiting this behavior present fundamental mathematical challenges in probability and statistics. The broad span of length and time scales associated with heavy tailed processes often require special sensitivity to distinctions between discrete and continuous phenomena. A discrete Highly Optimized Tolerance (HOT) model, referred to as the Probability, Loss, Resource (PLR) model, gives the exponent $\alpha=1/d$ as a function of the dimension $d$ of the underlying substrate in the sparse resource regime. This agrees well with data for wildfires, web file sizes, and electric power outages. However, another HOT model, based on a continuous (dense) distribution of resources, predicts $\alpha= 1+ 1/d $. In this paper we describe and analyze a third model, the cuts model, which exhibits both behaviors but in different regimes. We use the cuts model to show all three models agree in the dense resource limit. In the sparse resource regime, the continuum model breaks down, but in this case, the cuts and PLR models are described by the same exponent.
The Suppression of Immune System Disorders by Passive Attrition
Sean P. Stromberg,Jean M. Carlson
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0009648
Abstract: Exposure to infectious diseases has an unexpected benefit of inhibiting autoimmune diseases and allergies. This is one of many fundamental fitness tradeoffs associated with immune system architecture. The immune system attacks pathogens, but also may (inappropriately) attack the host. Exposure to pathogens can suppress the deleterious response, at the price of illness and the decay of immunity to previous diseases. This “hygiene hypothesis” has been associated with several possible underlying biological mechanisms. This study focuses on physiological constraints that lead to competition for survival between immune system cell types. Competition maintains a relatively constant total number of cells within each niche. The constraint implies that adding cells conferring new immunity requires loss (passive attrition) of some cells conferring previous immunities. We consider passive attrition as a mechanism to prevent the initial proliferation of autoreactive cells, thus preventing autoimmune disease. We see that this protection is a general property of homeostatic regulation and we look specifically at both the IL-15 and IL-7 regulated niches to make quantitative predictions using a mathematical model. This mathematical model yields insight into the dynamics of the “Hygiene Hypothesis,” and makes quantitative predictions for experiments testing the ability of passive attrition to suppress immune system disorders. The model also makes a prediction of an anti-correlation between prevalence of immune system disorders and passive attrition rates.
Dynamics of Polymer Molecules with Sacrificial Bond and Hidden Length Systems: Towards a Physically-Based Mesoscopic Constitutive Law
Ahmed E. Elbanna, Jean M. Carlson
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0056118
Abstract: We investigate the entropic force-elongation behavior of a polymer chain in the presence of the sacrificial bond and hidden length (SBHL) system observed experimentally in many biomaterials. We show that in most cases the SBHL system leads to a significant increase in toughness. However, the presence of a large number of bonds or relatively strong bonds in the SBHL system can reduce the net gain in toughness. We also incorporate the polymer model into a network of polymers with random properties (e.g., contour length, number and strength of sacrificial bonds, length of hidden loops). This allows us to derive a physically-based mesoscopic force-displacement law that governs the collective behavior.
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