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https://www.readbyqxmd.com/read/28328501/monte-carlo-simulations-of-diffusion-weighted-mri-in-myocardium-validation-and-sensitivity-analysis
#1
Joanne Bates, Darryl McClymont, Irvin Teh, Peter Kohl, Jurgen Schneider, Vicente Grau
A model of cardiac microstructure and diffusion MRI is presented, and compared with experimental data from ex vivo rat hearts. The model includes a simplified representation of individual cells, with physiologically correct cell size and orientation, as well as intra- to extracellular volume ratio. Diffusion MRI is simulated using a Monte Carlo model and realistic MRI sequences. The results show good correspondence between the simulated and experimental MRI signals. Similar patterns are observed in the eigenvalues of the diffusion tensor, the mean diffusivity (MD) and the fractional anisotropy (FA)...
March 10, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28328499/importance-of-matching-physical-friction-hardness-and-texture-in-creating-realistic-haptic-virtual-surfaces
#2
Heather Culbertson, Katherine J Kuchenbecker
Interacting with physical objects through a tool elicits tactile and kinesthetic sensations that comprise your haptic impression of the object. These cues, however, are largely missing from interactions with virtual objects, yielding an unrealistic user experience. This article evaluates the realism of virtual surfaces rendered using haptic models constructed from data recorded during interactions with real surfaces. The models include three components: surface friction, tapping transients, and texture vibrations...
January 2017: IEEE Transactions on Haptics
https://www.readbyqxmd.com/read/28328291/evaluation-of-multi-parameter-test-statistics-for-multiple-imputation
#3
Yu Liu, Craig K Enders
In Ordinary Least Square regression, researchers often are interested in knowing whether a set of parameters is different from zero. With complete data, this could be achieved using the gain in prediction test, hierarchical multiple regression, or an omnibus F test. However, in substantive research scenarios, missing data often exist. In the context of multiple imputation, one of the current state-of-art missing data strategies, there are several different analogous multi-parameter tests of the joint significance of a set of parameters, and these multi-parameter test statistics can be referenced to various distributions to make statistical inferences...
March 22, 2017: Multivariate Behavioral Research
https://www.readbyqxmd.com/read/28326627/obituary-thomas-earl-starzl-the-father-of-transplantation-march-11-1926-march-4-2017-to-be-published-in-esot-newsletter-transplant-international
#4
Jan P Lerut
March 2016…the transplant community celebrated with pomp the 90(th) birthday of transplantation pioneer, Th. E. Starzl. More than 400 surgeons and scientists originating from all over the United States and from all five continents met in Pittsburgh to pay tribute to their mentor, teacher and friend. The 'Starzl family at large' experienced a once in a lifetime event ending with a thoughtful, but typical (Fig. 1) 'Starzl speech' about past and future, including a humoristic but realistic view on life and ageing...
March 22, 2017: Transplant International: Official Journal of the European Society for Organ Transplantation
https://www.readbyqxmd.com/read/28326607/effect-of-apparent-depth-cues-on-accommodation-in-a-badal-optometer
#5
Carles Otero, Mikel Aldaba, Beatriz Martínez-Navarro, Jaume Pujol
BACKGROUND: The aim was to analyse the effect of peripheral depth cues on accommodation in Badal optometers. METHODS: Monocular refractions at 0.17 and 5.00 D of accommodative stimulus were measured with the PowerRef II autorefractor (Plusoptix Inc., Atlanta, Georgia, USA). Subjects looked (randomly) at four different scenes, one real scene comprising familiar objects at different depth planes (Real) and three virtual scenes comprising different two-dimensional pictures seen through a Badal lens...
March 21, 2017: Clinical & Experimental Optometry: Journal of the Australian Optometrical Association
https://www.readbyqxmd.com/read/28326088/temperature-effects-on-biomass-and-regeneration-of-vegetation-in-a-geothermal-area
#6
Abdul Nishar, Martin K-F Bader, Eoin J O'Gorman, Jieyu Deng, Barbara Breen, Sebastian Leuzinger
Understanding the effects of increasing temperature is central in explaining the effects of climate change on vegetation. Here, we investigate how warming affects vegetation regeneration and root biomass and if there is an interactive effect of warming with other environmental variables. We also examine if geothermal warming effects on vegetation regeneration and root biomass can be used in climate change experiments. Monitoring plots were arranged in a grid across the study area to cover a range of soil temperatures...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28324978/influence-of-electrode-configuration-on-the-electric-field-distribution-during-transcutaneous-spinal-direct-current-stimulation-of-the-cervical-spine
#7
Sofia R Fernandes, Ricardo Salvador, Cornelia Wenger, Mamede A de Carvalho, Pedro C Miranda
Transcutaneous spinal direct current stimulation (tsDCS) is a recent technique with promising neuromodulatory effects on spinal neuronal circuitry. The main objective of the present study was to perform a finite element analysis of the electric field distribution in tsDCS in the cervical spine region, with varying electrode configurations and geometry. A computational model of a human trunk was generated with nine tissue meshes. Three electrode configurations were tested: A) rectangular saline-soaked sponge target and return electrodes placed over C3 and T3 spinous processes, respectively; B1) circular saline-soaked sponge target and return electrodes placed over C7 spinous process and right deltoid muscle, respectively; B2) same configuration as B1, considering circular shaped electrodes with sponge and rubber layers and a small circular connector on the top surface...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28324925/non-invasive-imaging-of-ventricular-activation-during-pacing-and-arrhythmia-methods-and-validation
#8
Long Yu, Steven Pogwizd, Bin He
Cardiovascular disease continued to be a leading killer world widely. Each year, about 400,000 cases of sudden cardiac arrest are reported in the U.S. alone. Clinically, radio-frequency ablative procedure has become widely applied in the treatment of ventricular arrhythmia. Non-invasive approaches have been demonstrated to be able to provide important information on the arrhythmogenesis and potentially assist in the clinical practice. In this work, we develop and validate a novel temporal sparse based imaging method, Cardiac Electrical Sparse Imaging (CESI)...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28324193/hemodynamic-characterization-of-peripheral-arterio-venous-malformations
#9
Sabrina Frey, A Haine, R Kammer, H von Tengg-Kobligk, D Obrist, I Baumgartner
Peripheral arterio-venous malformations (pAVMs) are congenital vascular anomalies that require treatment, due to their severe clinical consequences. The complexity of lesions often leads to misdiagnosis and ill-planned treatments. To improve disease management, we developed a computational model to quantify the hemodynamic effects of key angioarchitectural features of pAVMs. Hemodynamic results were used to predict the transport of contrast agent (CA), which allowed us to compare our findings to digital subtraction angiography (DSA) recordings of patients...
March 21, 2017: Annals of Biomedical Engineering
https://www.readbyqxmd.com/read/28323642/a-bayesian-approach-for-three-dimensional-markerless-tumor-tracking-using-kv-imaging-during-lung-radiotherapy
#10
Chun-Chien Shieh, Vincent Caillet, Michelle Dunbar, Paul J Keall, Jeremy T Booth, Nicholas Hardcastle, Carol Haddad, Thomas Eade, Ilana Feain
The ability to monitor tumor motion without implanted markers can potentially enable broad access to more accurate and precise lung radiotherapy. A major challenge is that kilovoltage (kV) imaging based methods are rarely able to continuously track the tumor due to the inferior tumor visibility on 2D kV images. Another challenge is the estimation of 3D tumor position based on only 2D imaging information. The aim of this work is to address both challenges by proposing a Bayesian approach for markerless tumor tracking for the first time...
March 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28323592/measuring-uptake-and-elimination-of-nitrogen-in-humans-at-different-ambient-pressures
#11
Patrik Sundblad, Oskar Frånberg, Christoph Siebenmann, Mikael Gennser
BACKGROUND: To measure nitrogen (N2) wash-out and uptake requires elaborate set-ups, especially when doing the measurements at increased or decreased ambient pressure. Here we present a transportable device for quantifying N2 turnover in humans which can be used at different ambient pressures. METHODS: A modified close-circuit electronic rebreather was used to assess N2 turnover. Changes in N2 volume within the rebreathing circuit, reflecting N2 uptake or washout, were derived from the continuously monitored total system volume and the calculated volumes of oxygen and water vapor...
December 1, 2016: Aerospace Medicine and Human Performance
https://www.readbyqxmd.com/read/28323161/seeg-dipole-source-localization-based-on-an-empirical-bayesian-approach-taking-into-account-forward-model-uncertainties
#12
S Le Cam, R Ranta, V Caune, G Korats, L Koessler, L Maillard, V Louis-Dorr
Electromagnetic brain source localization consists in the inversion of a forward model based on a limited number of potential measurements. A wide range of methods has been developed to regularize this severely ill-posed problem and to reduce the solution space, imposing spatial smoothness, anatomical constraint or sparsity of the activated source map. This last criteria, based on physiological assumptions stating that in some particular events (e.g., epileptic spikes, evoked potential) few focal area of the brain are simultaneously actives, has gained more and more interest...
March 17, 2017: NeuroImage
https://www.readbyqxmd.com/read/28322757/impaired-clinical-utility-of-sequential-patient-gem-blood-gas-measurements-associated-with-calibration-schedule
#13
George S Cembrowski, Qian Xu, Adam R Cembrowski, Junyi Mei, Hossein Sadrzadeh
BACKGROUND: Within- and/or between-instrument variation may falsely indicate patient trends or obscure real trends. We employ a methodology that transforms sequential intra-patient results into estimates of biologic and analytic variation. We previously derived realistic biologic variation (sb) of blood gas (BG) and hematology analytes. We extend this methodology to derive the imprecision of two GEM 4000 BG analyzers. METHODS: A laboratory data repository provided arterial BG, electrolyte and metabolite results generated by two GEM 4000s on ICU patients in 2012-2013...
March 18, 2017: Clinical Biochemistry
https://www.readbyqxmd.com/read/28322230/reconstruction-of-noise-driven-nonlinear-networks-from-node-outputs-by-using-high-order-correlations
#14
Yang Chen, Zhaoyang Zhang, Tianyu Chen, Shihong Wang, Gang Hu
Many practical systems can be described by dynamic networks, for which modern technique can measure their outputs, and accumulate extremely rich data. Nevertheless, the network structures producing these data are often deeply hidden in the data. The problem of inferring network structures by analyzing the available data, turns to be of great significance. On one hand, networks are often driven by various unknown facts, such as noises. On the other hand, network structures of practical systems are commonly nonlinear, and different nonlinearities can provide rich dynamic features and meaningful functions of realistic networks...
March 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28322209/complex-interactive-effects-of-water-mold-herbicide-and-the-fungus-batrachochytrium-dendrobatidis-on-pacific-treefrog-hyliola-regilla-hosts
#15
John M Romansic, James E Johnson, R Steven Wagner, Rebecca H Hill, Christopher A Gaulke, Vance T Vredenburg, Andrew R Blaustein
Infectious diseases pose a serious threat to global biodiversity. However, their ecological impacts are not independent of environmental conditions. For example, the pathogenic fungus Batrachochytrium dendrobatidis (Bd), which has contributed to population declines and extinctions in many amphibian species, interacts with several environmental factors to influence its hosts, but potential interactions with other pathogens and environmental contaminants are understudied. We examined the combined effects of Bd, a water mold (Achlya sp...
March 21, 2017: Diseases of Aquatic Organisms
https://www.readbyqxmd.com/read/28321699/magnetic-edta-functionalized-cofe2o4-nanoparticles-edta-cofe2o4-as-a-novel-catalyst-for-peroxymonosulfate-activation-and-degradation-of-orange-g
#16
Lin Deng, Zhou Shi, Zhiyan Zou, Shiqing Zhou
EDTA functionalized CoFe2O4 nanoparticles (EDTA-CoFe2O4) synthesized using a facile one-pot solvothermal method were employed as catalysts to activate peroxymonosulfate (PMS) with Orange G (OG) as the target pollutant. Effects of operating parameters including initial solution pH, catalyst dosage, PMS dosage, and water matrix components such as Cl(-), NO3(-), CO3(2-), and humic acid were evaluated. A degradation efficiency of 93% was achieved in 15 min with 1 mM PMS and 0.2 g/L EDTA-CoFe2O4 catalyst, while only 57% of OG was degraded within 15 min in CoFe2O4/PMS system...
March 20, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28321614/freeze-thaw-revival-of-rotifers-and-algae-in-a-desiccated-high-elevation-5500-meters-microbial-mat-high-andes-per%C3%A3%C2%BA
#17
S K Schmidt, J L Darcy, Pacifica Sommers, Eva Gunawan, J E Knelman, Karina Yager
This is the first study of the highest elevation cyanobacteria-dominated microbial mat yet described. The desiccated mat was sampled in 2010 from an ephemeral rock pool at 5500 m above sea level in the Cordillera Vilcanota of southern Perú. After being frozen for 6 years at -20 °C in the lab, pieces of the mat were sequenced to fully characterize both the 16 and 18S microbial communities and experiments were conducted to determine if organisms in the mat could revive and become active under the extreme freeze-thaw conditions that these mats experience in the field...
March 21, 2017: Extremophiles: Life Under Extreme Conditions
https://www.readbyqxmd.com/read/28320890/a-biophysical-vascular-bubble-model-for-devising-decompression-procedures
#18
Ran Arieli, Abraham Marmur
Vascular bubble models, which present a realistic biophysical approach, hold great promise for devising suitable diver decompression procedures. Nanobubbles were found to nucleate on a flat hydrophobic surface, expanding to form bubbles after decompression. Such active hydrophobic spots (AHS) were formed from lung surfactants on the luminal aspect of ovine blood vessels. Many of the phenomena observed in these bubbling vessels correlated with those known to occur in diving. On the basis of our previous studies, which proposed a new model for the formation of arterial bubbles, we now suggest the biophysical model presented herein...
March 2017: Physiological Reports
https://www.readbyqxmd.com/read/28320798/interventions-to-improve-the-self-management-support-health-professionals-provide-for-people-with-progressive-neurological-conditions-protocol-for-a-realist-synthesis
#19
Freya Davies, Fiona Wood, Alison Bullock, Carolyn Wallace, Adrian Edwards
INTRODUCTION: Supporting self-management among people with long-term conditions is recognised as an important component of healthcare. Progressive neurological conditions (PNCs), for example, Parkinson's disease and multiple sclerosis are associated with problems such as fatigue and cognitive impairment which may make self-management more challenging. Health professionals may need to develop specific skills in order to provide effective self-management support for these patients. The review aims to develop explanatory theories about how health professional-targeted interventions to improve self-management support provision for people with PNCs operate in different circumstances...
March 20, 2017: BMJ Open
https://www.readbyqxmd.com/read/28320664/blind-forensics-of-successive-geometric-transformations-in-digital-images-using-spectral-method-theory-and-applications
#20
Jiangqun Ni, Chenglong Chen, Zhaoyi Shen, Yun-Qing Shi
Geometric transformations, such as resizing and rotation, are almost always needed when two or more images are spliced together to create convincing image forgeries. In recent years, researchers have developed many digital forensic techniques to identify these operations. Most previous works in this area focus on the analysis of images that have undergone single geometric transformations, e.g., resizing or rotation. In several recent works, researchers have addressed yet another practical and realistic situation: successive geometric transformations, e...
March 15, 2017: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
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