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'Dynamic linear model'

Yang Lei, Matthew S Mayo, Susan E Carlson, Byron J Gajewski
Personalized medicine aims to match patient subpopulation to the most beneficial treatment. The purpose of this study is to design a prospective clinical trial in which we hope to achieve the highest level of confirmation in identifying and making treatment recommendations for subgroups, when the risk levels in the control arm can be ordered. This study was motivated by our goal to identify subgroups in a DHA (docosahexaenoic acid) supplementation trial to reduce preterm birth (gestational age<37 weeks) rate...
March 2017: Contemporary Clinical Trials Communications
E Agnes Blukacz-Richards, Ariola Visha, Matthew L Graham, Daryl L McGoldrick, Shane R de Solla, David J Moore, George B Arhonditsis
Total mercury levels in aquatic birds and fish communities have been monitored across the Canadian Great Lakes by Environment and Climate Change Canada (ECCC) for the past 42 years (1974-2015). These data (22 sites) were used to examine spatio-temporal variability of mercury levels in herring gull (Larus argentatus) eggs, lake trout (Salvelinus namaycush), walleye (Sander vitreus), and rainbow smelt (Osmerus mordax). Trends were quantified with dynamic linear models, which provided time-variant rates of change of mercury concentrations...
April 2017: Chemosphere
Huiling Tan, Alek Pogosyan, Keyoumars Ashkan, Alexander L Green, Tipu Aziz, Thomas Foltynie, Patricia Limousin, Ludvic Zrinzo, Marwan Hariz, Peter Brown
The basal ganglia are known to be involved in the planning, execution and control of gripping force and movement vigour. Here we aim to define the nature of the basal ganglia control signal for force and to decode gripping force based on local field potential (LFP) activities recorded from the subthalamic nucleus (STN) in patients with deep brain stimulation (DBS) electrodes. We found that STN LFP activities in the gamma (55-90 Hz) and beta (13-30m Hz) bands were most informative about gripping force, and that a first order dynamic linear model with these STN LFP features as inputs can be used to decode the temporal profile of gripping force...
November 18, 2016: ELife
Yongqiu Xia, Donald E Weller, Meghan N Williams, Thomas E Jordan, Xiaoyuan Yan
Export coefficient models (ECMs) are often used to predict nutrient sources and sinks in watersheds because ECMs can flexibly incorporate processes and have minimal data requirements. However, ECMs do not quantify uncertainties in model structure, parameters, or predictions; nor do they account for spatial and temporal variability in land characteristics, weather, and management practices. We applied Bayesian hierarchical methods to address these problems in ECMs used to predict nitrate concentration in streams...
November 15, 2016: Water Research
C Hildebrandt Jørgensen, A R Kristensen, S Østergaard, T W Bennedsgaard
An automated method for determining whether dairy cows with subclinical mammary infections recover after antibiotic treatment would be a useful tool in dairy production. For that purpose, inline l-lactate dehydrogenase (LDH) measurements was modeled using a dynamic linear model; the variance parameters were estimated using the expectation-maximization algorithm. The method used to classify cows as infected or uninfected was based on a multiprocess Kalman filter. Two learning data sets were created: infected and uninfected...
October 2016: Journal of Dairy Science
Dan B Jensen, Henk Hogeveen, Albert De Vries
Rapid detection of dairy cow mastitis is important so corrective action can be taken as soon as possible. Automatically collected sensor data used to monitor the performance and the health state of the cow could be useful for rapid detection of mastitis while reducing the labor needs for monitoring. The state of the art in combining sensor data to predict clinical mastitis still does not perform well enough to be applied in practice. Our objective was to combine a multivariate dynamic linear model (DLM) with a naïve Bayesian classifier (NBC) in a novel method using sensor and nonsensor data to detect clinical cases of mastitis...
September 2016: Journal of Dairy Science
A H Stygar, A R Kristensen
Application of BW monitoring methods for the whole batch of pigs is not common in commercial herds. Instead, farm managers may regularly weigh a chosen subset of pigs (observed group) and use the obtained information for monitoring, forecasting, and decision support. The objective of this study was to construct a model for growth monitoring and forecasting in pig fattening herds and use the developed model framework to quantify the value of information on BW. The dynamic process of pig growing was described by means of a dynamic linear model (DLM) with Kalman filtering...
March 2016: Journal of Animal Science
Francisco Torres-Avilés, Tomás Moraga, Loreto Núñez, Gloria Icaza
The objectives were to analyze lung cancer mortality trends in Chile from 1990 to 2009, and to project the rates six years forward. Lung cancer mortality data were obtained from the Chilean Ministry of Health. To obtain mortality rates, population projections were used, based on the 2002 National Census. Rates were adjusted using the world standard population as reference. Bayesian dynamic linear models were fitted to estimate trends from 1990 to 2009 and to obtain projections for 2010-2015. During the period under study, there was a 19...
September 2015: Cadernos de Saúde Pública
Christian Holm Hansen, Pamela Warner, Richard A Parker, Brian R Walker, Hilary Od Critchley, Christopher J Weir
It is often unclear what specific adaptive trial design features lead to an efficient design which is also feasible to implement. This article describes the preparatory simulation study for a Bayesian response-adaptive dose-finding trial design. Dexamethasone for Excessive Menstruation aims to assess the efficacy of Dexamethasone in reducing excessive menstrual bleeding and to determine the best dose for further study. To maximise learning about the dose response, patients receive placebo or an active dose with randomisation probabilities adapting based on evidence from patients already recruited...
September 30, 2015: Statistical Methods in Medical Research
Yingying Hu, Shiyao Bian, John Grotberg, Marcel Filoche, Joshua White, Shuichi Takayama, James B Grotberg
Fluid dynamics of mucus plug rupture is important to understand mucus clearance in lung airways and potential effects of mucus plug rupture on epithelial cells at lung airway walls. We established a microfluidic model to study mucus plug rupture in a collapsed airway of the 12th generation. Mucus plugs were simulated using Carbopol 940 (C940) gels at concentrations of 0.15%, 0.2%, 0.25%, and 0.3%, which have non-Newtonian properties close to healthy and diseased lung mucus. The airway was modeled with a polydimethylsiloxane microfluidic channel...
July 2015: Biomicrofluidics
A F Garcia, A M S Simão, M Bolean, M F Hoylaerts, J L Millán, P Ciancaglini, A J Costa-Filho
Tissue-nonspecific alkaline phosphatase (TNAP) plays a crucial role during skeletal mineralization, and TNAP deficiency leads to the soft bone disease hypophosphatasia. TNAP is anchored to the external surface of the plasma membranes by means of a GPI (glycosylphosphatidylinositol) anchor. Membrane-anchored and solubilized TNAP displays different kinetic properties against physiological substrates, indicating that membrane anchoring influences the enzyme function. Here, we used Electron Spin Resonance (ESR) measurements along with spin labeled phospholipids to probe the possible dynamic changes prompted by the interaction of GPI-anchored TNAP with model membranes...
October 21, 2015: Physical Chemistry Chemical Physics: PCCP
Björn Herrmann, Molly J Henry, Saskia Haegens, Jonas Obleser
Alignment of neural oscillations with temporally regular input allows listeners to generate temporal expectations. However, it remains unclear how behavior is governed in the context of temporal variability: What role do temporal expectations play, and how do they interact with the strength of neural oscillatory activity? Here, human participants detected near-threshold targets in temporally variable acoustic sequences. Temporal expectation strength was estimated using an oscillator model and pre-target neural amplitudes in auditory cortex were extracted from magnetoencephalography signals...
January 1, 2016: NeuroImage
Christopher F Shay, Michele Ferrante, G William Chapman, Michael E Hasselmo
Rebound spiking properties of medial entorhinal cortex (mEC) stellate cells induced by inhibition may underlie their functional properties in awake behaving rats, including the temporal phase separation of distinct grid cells and differences in grid cell firing properties. We investigated rebound spiking properties using whole cell patch recording in entorhinal slices, holding cells near spiking threshold and delivering sinusoidal inputs, superimposed with realistic inhibitory synaptic inputs to test the capacity of cells to selectively respond to specific phases of inhibitory input...
March 2016: Neurobiology of Learning and Memory
Kisic-Tepavcevic Darija, Pekmezovic Tatjana, Trajkovic Goran, Stojsavljevic Nebojsa, Dujmovic Irena, Mesaros Sarlota, Drulovic Jelena
PURPOSE: Sexual dysfunction (SD) is a common but often overlooked and undertreated symptom in multiple sclerosis (MS). The purpose of our longitudinal study was to explore the changes in the level of sexual functioning in MS cohort after a period of 3 and 6 years of follow-up, as well as to investigate the predictors of changes in SD during the period of observation. METHODS: The study population comprise a cohort of 93 patients with MS (McDonald's criteria, 2001) who were assessed at three time points during the study (baseline, and at the 3- and 6-year follow-up)...
November 15, 2015: Journal of the Neurological Sciences
Christopher P Calderon, Kerry Bloom
Understanding the basis for intracellular motion is critical as the field moves toward a deeper understanding of the relation between Brownian forces, molecular crowding, and anisotropic (or isotropic) energetic forcing. Effective forces and other parameters used to summarize molecular motion change over time in live cells due to latent state changes, e.g., changes induced by dynamic micro-environments, photobleaching, and other heterogeneity inherent in biological processes. This study discusses limitations in currently popular analysis methods (e...
2015: PloS One
Liming Ling, Li-Chen Zhao
We study integrable coupled nonlinear Schrödinger equations with pair particle transition between components. Based on exact solutions of the coupled model with attractive or repulsive interaction, we predict that some new dynamics of nonlinear excitations can exist, such as the striking transition dynamics of breathers, new excitation patterns for rogue waves, topological kink excitations, and other new stable excitation structures. In particular, we find that nonlinear wave solutions of this coupled system can be written as a linear superposition of solutions for the simplest scalar nonlinear Schrödinger equation...
August 2015: Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
Keli Yang, Xingang Wang, Shi-Xian Qu
Cyclic collective behaviors are commonly observed in biological and neuronal systems, yet the dynamical origins remain unclear. Here, by models of coupled discontinuous map lattices, we investigate the cyclic collective behaviors by means of cluster synchronization. Specifically, we study the synchronization behaviors in lattices of coupled periodic piecewise-linear maps and find that in the nonsynchronous regime the maps can be synchronized into different clusters and, as the system evolves, the synchronous clusters compete with each other and present the recurring process of cluster expanding, shrinking, and switching, i...
August 2015: Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
Yang Qi, Pulin Gong
The formation of dynamic patterns such as localized propagating waves is a fascinating self-organizing phenomenon that happens in a wide range of spatially extended systems including neural systems, in which they might play important functional roles. Here we derive a type of two-dimensional neural-field model with refractoriness to study the formation mechanism of localized waves. After comparing this model with existing neural-field models, we show that it is able to generate a variety of localized patterns, including stationary bumps, localized waves rotating along a circular path, and localized waves with longer-range propagation...
August 2015: Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
Anupama Reddy, Joseph D Growney, Nick S Wilson, Caroline M Emery, Jennifer A Johnson, Rebecca Ward, Kelli A Monaco, Joshua Korn, John E Monahan, Mark D Stump, Felipa A Mapa, Christopher J Wilson, Janine Steiger, Jebediah Ledell, Richard J Rickles, Vic E Myer, Seth A Ettenberg, Robert Schlegel, William R Sellers, Heather A Huet, Joseph Lehár
Death Receptor 5 (DR5) agonists demonstrate anti-tumor activity in preclinical models but have yet to demonstrate robust clinical responses. A key limitation may be the lack of patient selection strategies to identify those most likely to respond to treatment. To overcome this limitation, we screened a DR5 agonist Nanobody across >600 cell lines representing 21 tumor lineages and assessed molecular features associated with response. High expression of DR5 and Casp8 were significantly associated with sensitivity, but their expression thresholds were difficult to translate due to low dynamic ranges...
2015: PloS One
J Patrick Mayo, Amie R DiTomasso, Marc A Sommer, Matthew A Smith
Neuronal receptive fields (RFs) provide the foundation for understanding systems-level sensory processing. In early visual areas, investigators have mapped RFs in detail using stochastic stimuli and sophisticated analytical approaches. Much less is known about RFs in prefrontal cortex. Visual stimuli used for mapping RFs in prefrontal cortex tend to cover a small range of spatial and temporal parameters, making it difficult to understand their role in visual processing. To address these shortcomings, we implemented a generalized linear model to measure the RFs of neurons in the macaque frontal eye field (FEF) in response to sparse, full-field stimuli...
December 2015: Journal of Neurophysiology
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