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Generic error modelling system

S Weppler, P McGeachy, J Villarreal-Barajas, R Khan
PURPOSE: Multileaf collimator (MLC) leaf sequencing is performed via commercial black-box implementations, on which a user has limited to no access. We have developed an explicit, generic MLC sequencing model to serve as a tool for future investigations of fluence map optimization, fluence delivery optimization, and rotational collimator delivery methods. METHODS: We have developed a novel, comprehensive model to effectively account for a variety of transmission and penumbra effects previously treated on an ad hoc basis in the literature...
June 2016: Medical Physics
M Glitzner, M F Fast, B Denis de Senneville, S Nill, U Oelfke, J J W Lagendijk, B W Raaymakers, S P M Crijns
In radiotherapy, abdominal and thoracic sites are candidates for performing motion tracking. With real-time control it is possible to adjust the multileaf collimator (MLC) position to the target position. However, positions are not perfectly matched and position errors arise from system delays and complicated response of the electromechanic MLC system. Although, it is possible to compensate parts of these errors by using predictors, residual errors remain and need to be compensated to retain target coverage...
January 7, 2017: Physics in Medicine and Biology
Yumi Yamamoto, Pyry A Välitalo, Dirk-Jan van den Berg, Robin Hartman, Willem van den Brink, Yin Cheong Wong, Dymphy R Huntjens, Johannes H Proost, An Vermeulen, Walter Krauwinkel, Suruchi Bakshi, Vincent Aranzana-Climent, Sandrine Marchand, Claire Dahyot-Fizelier, William Couet, Meindert Danhof, Johan G C van Hasselt, Elizabeth C M de Lange
PURPOSE: Predicting target site drug concentration in the brain is of key importance for the successful development of drugs acting on the central nervous system. We propose a generic mathematical model to describe the pharmacokinetics in brain compartments, and apply this model to predict human brain disposition. METHODS: A mathematical model consisting of several physiological brain compartments in the rat was developed using rich concentration-time profiles from nine structurally diverse drugs in plasma, brain extracellular fluid, and two cerebrospinal fluid compartments...
February 2017: Pharmaceutical Research
Andrew Y-Z Ou, Yu Jiang, Po-Liang Wu, Lui Sha, Richard B Berlin
In a medical environment such as Intensive Care Unit, there are many possible reasons to cause errors, and one important reason is the effect of human intellectual tasks. When designing an interactive healthcare system such as medical Cyber-Physical-Human Systems (CPHSystems), it is important to consider whether the system design can mitigate the errors caused by these tasks or not. In this paper, we first introduce five categories of generic intellectual tasks of humans, where tasks among each category may lead to potential medical errors...
January 2017: Journal of Medical Systems
Tasnim Hamza, Mohammad-Ali Khalighi, Salah Bourennane, Pierre Léon, Jan Opderbecke
We investigate the effect of environmental noise, caused by solar radiations under water, on the performance of underwater wireless optical communication (UWOC) systems. Presenting an analytical and generic model for this noise, we examine its impact on the link performance in terms of the bit error rate (BER). This study is conducted for different photo-detector types in the aim of highlighting practical limitations of establishing UWOC links in the presence of subsea solar noise. We show how the solar noise can impact the performance of UWOC links for relatively low operation depths...
October 31, 2016: Optics Express
C Pizzolato, M Reggiani, L Modenese, D G Lloyd
Real-time estimation of joint angles and moments can be used for rapid evaluation in clinical, sport, and rehabilitation contexts. However, real-time calculation of kinematics and kinetics is currently based on approximate solutions or generic anatomical models. We present a real-time system based on OpenSim solving inverse kinematics and dynamics without simplifications at 2000 frame per seconds with less than 31.5 ms of delay. We describe the software architecture, sensitivity analyses to minimise delays and errors, and compare offline and real-time results...
March 2017: Computer Methods in Biomechanics and Biomedical Engineering
Shawn M O'Connor, Jeremy D Wong, J Maxwell Donelan
While forcing of end-tidal gases by regulating inspired gas concentrations is a common technique for studying cardiorespiratory physiology, independently controlling end-tidal gases is technically challenging. Feedforward control methods are challenging because end-tidal values vary as a dynamic function of both inspired gases and other nonregulated physiological parameters. Conventional feedback control is limited by delays within the lungs and body tissues and within the end-tidal forcing system itself. Consequently, modern end-tidal forcing studies have generally restricted their analysis to simple time courses of end-tidal gases and to resting steady-state conditions...
December 1, 2016: Journal of Applied Physiology
Sean S Downey, W Randall Haas, Stephen J Shennan
Ecosystems on the verge of major reorganization-regime shift-may exhibit declining resilience, which can be detected using a collection of generic statistical tests known as early warning signals (EWSs). This study explores whether EWSs anticipated human population collapse during the European Neolithic. It analyzes recent reconstructions of European Neolithic (8-4 kya) population trends that reveal regime shifts from a period of rapid growth following the introduction of agriculture to a period of instability and collapse...
August 30, 2016: Proceedings of the National Academy of Sciences of the United States of America
Huizhe Liu, Jason Gao, Viet Phuong Bui, Zhengtong Liu, Kenneth Eng Kian Lee, Li-Shiuan Peh, Ching Eng Png
Active triangulation range finders are widely used in a variety of applications such as robotics and assistive technologies. The power of the laser source should be carefully selected in order to satisfy detectability and still remain eye-safe. In this paper, we present a systematic approach to assess the detectability of an active triangulation range finder in an outdoor environment. For the first time, we accurately quantify the background noise of a laser system due to solar irradiance by coupling the Perez all-weather sky model and ray tracing techniques...
June 27, 2016: Optics Express
Timothy L Fletcher, Paul L A Popelier
A machine learning method called kriging is applied to the set of all 20 naturally occurring amino acids. Kriging models are built that predict electrostatic multipole moments for all topological atoms in any amino acid based on molecular geometry only. These models then predict molecular electrostatic interaction energies. On the basis of 200 unseen test geometries for each amino acid, no amino acid shows a mean prediction error above 5.3 kJ mol(-1), while the lowest error observed is 2.8 kJ mol(-1). The mean error across the entire set is only 4...
June 14, 2016: Journal of Chemical Theory and Computation
Ivan Gregor, Johannes Dröge, Melanie Schirmer, Christopher Quince, Alice C McHardy
Background. Metagenomics is an approach for characterizing environmental microbial communities in situ, it allows their functional and taxonomic characterization and to recover sequences from uncultured taxa. This is often achieved by a combination of sequence assembly and binning, where sequences are grouped into 'bins' representing taxa of the underlying microbial community. Assignment to low-ranking taxonomic bins is an important challenge for binning methods as is scalability to Gb-sized datasets generated with deep sequencing techniques...
2016: PeerJ
Kassaye Tolessa, Michael Rademaker, Bernard De Baets, Pascal Boeckx
The growing global demand for specialty coffee increases the need for improved coffee quality assessment methods. Green bean coffee quality analysis is usually carried out by physical (e.g. black beans, immature beans) and cup quality (e.g. acidity, flavour) evaluation. However, these evaluation methods are subjective, costly, time consuming, require sample preparation and may end up in poor grading systems. This calls for the development of a rapid, low-cost, reliable and reproducible analytical method to evaluate coffee quality attributes and eventually chemical compounds of interest (e...
April 1, 2016: Talanta
Elizabeth Goodwin, Colin Green, Anne Spencer
BACKGROUND: Condition-specific measures are frequently used to assess the health-related quality of life of people with multiple sclerosis (MS). Such measures are unsuitable for use in economic evaluations that require estimates of cost per quality-adjusted life-year because they are not based on preferences. OBJECTIVES: To report the estimation of a preference-based single index for an eight-dimensional instrument for MS, the Multiple Sclerosis Impact Scale - Eight Dimensions (MSIS-8D), derived from an MS-specific measure of health-related quality of life, the 29-item Multiple Sclerosis Impact Scale (MSIS-29)...
December 2015: Value in Health: the Journal of the International Society for Pharmacoeconomics and Outcomes Research
Xiaoliang Sun, Bettina Länger, Wolfram Weckwerth
Inferring dynamics of metabolic networks directly from metabolomics data provides a promising way to elucidate the underlying mechanisms of biological systems, as reported in our previous studies (Weckwerth, 2011; Sun and Weckwerth, 2012; Nägele et al., 2014) by a differential Jacobian approach. The Jacobian is solved from an overdetermined system of equations as JC + CJ(T)  = -2D, called Lyapunov Equation in its generic form, where J is the Jacobian, C is the covariance matrix of metabolomics data, and D is the fluctuation matrix...
2015: Frontiers in Bioengineering and Biotechnology
Saqib Yousaf, Shiyin Qin
Blind image deconvolution (BID) aims to remove or reduce the degradations that have occurred during the acquisition or processing. It is a challenging ill-posed problem due to a lack of enough information in degraded image for unambiguous recovery of both point spread function (PSF) and clear image. Although recently many powerful algorithms appeared; however, it is still an active research area due to the diversity of degraded images as well as degradations. Closed-loop control systems are characterized with their powerful ability to stabilize the behavior response and overcome external disturbances by designing an effective feedback optimization...
December 2015: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Paul J Wensveen, Len Thomas, Patrick J O Miller
BACKGROUND: Detailed information about animal location and movement is often crucial in studies of natural behaviour and how animals respond to anthropogenic activities. Dead-reckoning can be used to infer such detailed information, but without additional positional data this method results in uncertainty that grows with time. Combining dead-reckoning with new Fastloc-GPS technology should provide good opportunities for reconstructing georeferenced fine-scale tracks, and should be particularly useful for marine animals that spend most of their time under water...
2015: Movement Ecology
Alberta Ipser, Richard Cook
Built on models of 'action understanding', motor theories of expression perception propose that facial simulation, a process similar to covert imitation, aids perception and interpretation of others' facial expressions. As predicted by these accounts, some reports suggest that blocking facial mimicry impairs expression recognition. However, these reports have been criticized and motor theories remain controversial. Crucially, it remains to be determined whether the labeling errors observed reflect a loss of perceptual sensitivity - a genuine perceptual phenomenon - or whether they are a product of response bias...
2015: Journal of Vision
Helga Mazyar, Bosco Tjan
A saccade brings a retinal locus to a target in the visual field. For normally sighted individuals, this retinal locus is the fovea. Central field loss (CFL) caused by macular degeneration often leads to the adoption of a preferred retinal locus (PRL) in the peripheral retina for saccades and fixation. Factors underlying the development of a PRL are not known. Here we show that a conceptually simple computational model can account for the formation of a PRL and its idiosyncrasies. We assume that the visual system always intends to aim the retinal locus with the highest expected post-saccade acuity at the saccade target...
2015: Journal of Vision
Joseph A Ewing, Michelle K Kaufman, Erin E Hutter, Jeffrey F Granger, Matthew D Beal, Stephen J Piazza, Robert A Siston
Surgical technique is one factor that has been identified as critical to success of total knee arthroplasty. Researchers have shown that computer simulations can aid in determining how decisions in the operating room generally affect post-operative outcomes. However, to use simulations to make clinically relevant predictions about knee forces and motions for a specific total knee patient, patient-specific models are needed. This study introduces a methodology for estimating knee soft-tissue properties of an individual total knee patient...
March 2016: Journal of Orthopaedic Research: Official Publication of the Orthopaedic Research Society
Jan Kneissler, Jan Drugowitsch, Karl Friston, Martin V Butz
Predictive coding appears to be one of the fundamental working principles of brain processing. Amongst other aspects, brains often predict the sensory consequences of their own actions. Predictive coding resembles Kalman filtering, where incoming sensory information is filtered to produce prediction errors for subsequent adaptation and learning. However, to generate prediction errors given motor commands, a suitable temporal forward model is required to generate predictions. While in engineering applications, it is usually assumed that this forward model is known, the brain has to learn it...
2015: Frontiers in Computational Neuroscience
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