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Kernel density

David P Robinson, Mohammed Y Jaidah, Steffen S Bach, Christoph A Rohner, Rima W Jabado, Rupert Ormond, Simon J Pierce
The Arabian Gulf is the warmest sea in the world and is host to a globally significant population of the whale shark Rhincodon typus. To investigate regional whale shark behaviour and movements, 59 satellite-linked tags were deployed on whale sharks in the Al Shaheen area off Qatar from 2011-14. Four different models of tag were used throughout the study, each model able to collect differing data or quantities of data. Retention varied from one to 227 days. While all tagged sharks crossed international maritime boundaries, they typically stayed within the Arabian Gulf...
2017: PloS One
Felix A Faber, Luke Hutchison, Bing Huang, Justin Gilmer, Samuel S Schoenholz, George E Dahl, Oriol Vinyals, Steven Kearnes, Patrick F Riley, O Anatole von Lilienfeld
We investigate the impact of choosing regres- sors and molecular representations for the construction of fast machine learning (ML) models of thirteen electronic ground-state properties of organic molecules. The performance of each regressor/representation/property combination is assessed using learning curves which report out- of-sample errors as a function of training set size with up to ∼118k distinct molecules. Molecular structures and properties at hybrid density functional theory (DFT) level of theory come from the QM9 database [Ramakrishnan et al, Scientific Data 1 140022 (2014)] and include enthalpies and free energies of atomization , HOMO/LUMO energies and gap, dipole moment, polarizability, zero point vibrational energy, heat capacity and the highest fundamental vibrational frequency...
September 19, 2017: Journal of Chemical Theory and Computation
Julie McIntyre, Brent A Johnson, Stephen M Rappaport
Nonparametric regression is a fundamental problem in statistics but challenging when the independent variable is measured with error. Among the first approaches was an extension of deconvoluting kernel density estimators for homescedastic measurement error. The main contribution of this article is to propose a new simulation-based nonparametric regression estimator for the heteroscedastic measurement error case. Similar to some earlier proposals, our estimator is built on principles underlying deconvoluting kernel density estimators...
September 15, 2017: Biometrics
Yin Tian, Huiling Zhang, Wei Xu, Haiyong Zhang, Li Yang, Shuxing Zheng, Yupan Shi
Spectral entropy, which was generated by applying the Shannon entropy concept to the power distribution of the Fourier-transformed electroencephalograph (EEG), was utilized to measure the uniformity of power spectral density underlying EEG when subjects performed the working memory tasks twice, i.e., before and after training. According to Signed Residual Time (SRT) scores based on response speed and accuracy trade-off, 20 subjects were divided into two groups, namely high-performance and low-performance groups, to undertake working memory (WM) tasks...
2017: Frontiers in Human Neuroscience
Paula Villagra, Carolina Quintana
This study aimed to further our understanding of a characteristic of Community Resilience known as Disaster Governance. Three attributes of Disaster Governance-redundancy, diversity, and overlap-were studied in four coastal towns in southern Chile that are at risk of tsunamis. Overall, we explored how different spatial structures of human settlements influence Disaster Governance. Using the Projective Mapping Technique, the distribution of emergency institutions (N = 32) and uses given to specific sites (e...
September 14, 2017: International Journal of Environmental Research and Public Health
Evan L Ray, Krzysztof Sakrejda, Stephen A Lauer, Michael A Johansson, Nicholas G Reich
Creating statistical models that generate accurate predictions of infectious disease incidence is a challenging problem whose solution could benefit public health decision makers. We develop a new approach to this problem using kernel conditional density estimation (KCDE) and copulas. We obtain predictive distributions for incidence in individual weeks using KCDE and tie those distributions together into joint distributions using copulas. This strategy enables us to create predictions for the timing of and incidence in the peak week of the season...
September 14, 2017: Statistics in Medicine
Majid Khalilikhah, Kevin Heaslip
INTRODUCTION: Animal-vehicle collisions (AVCs) can result in serious injury and death to drivers, animals' death, and significant economic costs. However, the cost effectiveness of the majority of AVC mitigation measures is a significant issue. METHOD: A mobile-based data collection effort was deployed to measure signs under the Utah Department of Transportation's (UDOT) jurisdiction. The crash data were obtained from the UDOT risk management database. ArcGIS was employed to link these two data sets and extract animal-related crashes and signs...
September 2017: Journal of Safety Research
Jinyu Tian, Taiping Zhang, Anyong Qin, Zhaowei Shang, Yuan Yan Tang
This work proposes a new clustering method for images called Distribution Preserving Indexing (DPI). It aims to find a lower-dimensional semantic space approximating the original image space in the sense of preserving the distribution of the data. In the theory, the intrinsic structure of the data clusters can be described by the distribution of the data effectively. Therefore, the cluster structure of the data in a lower-dimensional semantic space derived by DPI becomes clear. Unlike these distance based clustering methods which reveal the intrinsic Euclidean structure of data, our method attempts to discover the intrinsic cluster structure of the data space that actually is the union of some sub-manifolds...
September 4, 2017: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Volodymyr Turkowski, Talat Shanaz Rahman
We formulate a rigorous method for calculating a nonadiabatic (frequency-dependent) exchange-correlation (XC) kernel appropriate for accurate description of both equilibrium and nonequilibrium properties of strongly correlated systems within the Time-Dependent Density Functional Theory (TDDFT) via the charge susceptibility, which is in turn obtained from Dynamical Mean Field Theory (DMFT) based on the effective multi-orbital Hubbard model. Application to the simple case of the one-orbital Hubbard model already shows the importance of the usage of the nonadiabatic kernel in TDDFT as it leads to significant modification of the excitation spectrum - shifting the (adiabatic) peak and disclosing another that is reminiscent of the solution from DMFT...
September 6, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Maya Khalifé, Brice Fernandez, Olivier Jaubert, Michael Soussan, Vincent Brulon, Irene Buvat, Claude Comtat
In brain PET/MR applications, accurate attenuation maps are required for accurate PET image quantification. An implemented attenuation correction (AC) method for brain imaging is the single-atlas approach which estimates an AC map from an averaged CT template. As an alternative, we propose to use a Zero Echo Time (ZTE) pulse sequence to segment bone, air and soft tissue. A linear relationship between histogram normalized ZTE intensity and measured CT density in Hounsfield Units (HU) in bone has been established thanks to a CT-MR database of 16 patients...
August 24, 2017: Physics in Medicine and Biology
Silvia Carvalho, Mônica de Avelar Figueiredo Mafra Magalhães, Roberto de Andrade Medronho
OBJECTIVE: Analyze the spatial distribution of classical dengue and severe dengue cases in the city of Rio de Janeiro. METHODS: Exploratory study, considering cases of classical dengue and severe dengue with laboratory confirmation of the infection in the city of Rio de Janeiro during the years 2011/2012. The georeferencing technique was applied for the cases notified in the Notification Increase Information System in the period of 2011 and 2012. For this process, the fields "street" and "number" were used...
August 17, 2017: Revista de Saúde Pública
Jianxiao Liu, Zonglin Tian
BACKGROUND AND OBJECTIVE: Mining the genes related to maize carotenoid components is important to improve the carotenoid content and the quality of maize. METHODS: On the basis of using the entropy estimation method with Gaussian kernel probability density estimator, we use the three-phase dependency analysis (TPDA) Bayesian network structure learning method to construct the network of maize gene and carotenoid components traits. RESULTS: In the case of using two discretization methods and setting different discretization values, we compare the learning effect and efficiency of 10 kinds of Bayesian network structure learning methods...
2017: BioMed Research International
Melissa S Cruz, Tania M AlarconFalconi, Meghan A Hartwick, Aishwarya Venkat, Hanna Y Ehrlich, Shalini Anandan, Honorine D Ward, Balaji Veeraraghavan, Elena N Naumova
Despite availability of high quality medical records, health care systems often do not have the resources or tools to utilize these data efficiently. Yet, hospital-based, laboratory-confirmed records may pave the way for building reliable surveillance systems capable of monitoring temporal trends of emerging infections. In this communication, we present a new tool to compress and visualize medical records with a local population profile (LPP) approach, which transforms information into statistically comparable patterns...
2017: PloS One
Valentina Petroulia, Manuela Funke, Pascal Zumstein, Sabina Berezowska, Lukas Ebner, Thomas Geiser, Nenad Torbica, Johannes Heverhagen, Alexander Poellinger
OBJECTIVES: Idiopathic pulmonary fibrosis (IPF) is a progressive lethal chronic lung disease with unclear pathogenesis. Radiological hallmark is the pattern of usual interstitial pneumonia accentuated in peripheral and basal areas with otherwise preserved lung structure. One hypothesis is that alveolar collapse and consequent induration lead to fibrotic transformation of lung tissue. The aim of the study was to investigate normal-appearing tissue during expiration for signs of collapsibility and differences from other diseases or controls...
August 16, 2017: Investigative Radiology
Abdulhamid Chaikh, Jacques Balosso
BACKGROUND: During the past decades, in radiotherapy, the dose distributions were calculated using density correction methods with pencil beam as type 'a' algorithm. The objectives of this study are to assess and evaluate the impact of dose distribution shift on the predicted secondary cancer risk (SCR), using modern advanced dose calculation algorithms, point kernel, as type 'b', which consider change in lateral electrons transport. METHODS: Clinical examples of pediatric cranio-spinal irradiation patients were evaluated...
June 2017: Quantitative Imaging in Medicine and Surgery
Ryohei Shibue, Fumiyasu Komaki
Neural decoding is a framework for reconstructing external stimuli from spike trains recorded in brains. Kloosterman et al. (2014) proposed a new decoding method using marked point processes. This method does not require spike sorting and thereby improves decoding accuracy dramatically. In this method, they used kernel density estimation to estimate intensity functions of marked point processes. However, using kernel density estimation causes problems. To overcome these problems, we propose a new decoding method using infinite mixture models to estimate intensity...
August 9, 2017: Journal of Neurophysiology
Shannon W Ricci, DelWayne R Bohnenstiehl, David B Eggleston, M Lisa Kellogg, R Patrick Lyon
During May 2015, passive acoustic recorders were deployed at eight subtidal oyster reefs within Harris Creek Oyster Sanctuary in Chesapeake Bay, Maryland USA. These sites were selected to represent both restored and unrestored habitats having a range of oyster densities. Throughout the survey, the soundscape within Harris Creek was dominated by the boatwhistle calls of the oyster toadfish, Opsanus tau. A novel, multi-kernel spectral correlation approach was developed to automatically detect these boatwhistle calls using their two lowest harmonic bands...
2017: PloS One
Anders M N Niklasson
Extended Lagrangian Born-Oppenheimer molecular dynamics [A. M. N. Niklasson, Phys. Rev. Lett. 100, 123004 (2008)] is formulated for general Hohenberg-Kohn density-functional theory and compared with the extended Lagrangian framework of first principles molecular dynamics by Car and Parrinello [Phys. Rev. Lett. 55, 2471 (1985)]. It is shown how extended Lagrangian Born-Oppenheimer molecular dynamics overcomes several shortcomings of regular, direct Born-Oppenheimer molecular dynamics, while improving or maintaining important features of Car-Parrinello simulations...
August 7, 2017: Journal of Chemical Physics
Graeme S Cumming, Dominic A W Henry, Chevonne Reynolds
Ecological theory predicts that if animals with very similar dietary requirements inhabit the same landscape, then they should avoid niche overlap by either exploiting food resources at different times or foraging at different spatial scales. Similarly, it is often assumed that animals that fall in different body mass modes and share the same body plan will use landscapes at different spatial scales. We developed a new methodological framework for understanding the scaling of foraging (i.e. the range and distribution of scales at which animals use their landscapes) by applying a combination of three well-established methods to satellite telemetry data to quantify foraging patch size distributions: (1) first-passage time analysis; (2) a movement-based kernel density estimator; and (3) statistical comparison of resulting histograms and tests for multimodality...
July 2017: Ecology and Evolution
Linda R Harris, Ronel Nel, Herman Oosthuizen, Mike Meyer, Deon Kotze, Darrell Anders, Steven McCue, Santosh Bachoo
Harnessing the economic potential of the oceans is key to combating poverty, enhancing food security, and strengthening economies. But the concomitant risk of intensified resource extraction to migratory species is worrying given that these species contribute to important ecological processes, often underpin alternatively livelihoods, and many are already threatened. We thus sought to quantify the potential conflict between key economic activities (five fisheries and hydrocarbon exploitation) and sea turtle migration corridors in a region with rapid economic development: Southern and East Africa...
August 2, 2017: Conservation Biology: the Journal of the Society for Conservation Biology
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