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Alina Svechkina, Jonathan Dubnov, Boris A Portnov
BACKGROUND: Low birth weight (LBW) is known to be associated with infant mortality and postnatal health complications. Previous studies revealed strong relationships between LBW rate and several socio-demographic factors, including ethnicity, maternal age, and family income. However, studies of association between LBW rate and environmental risk factors remain infrequent. STUDY METHODS: We retrieved a geo-referenced data set, containing 7216 individual records of children born in 2015 in the Haifa Bay Area in Israel...
May 17, 2018: Environmental Research
Rachael Al-Saadon, Christopher Sutton, Weitao Yang
Thermally activated delayed florescence (TADF) is a mechanism that increases the electroluminescence efficiency in organic light-emitting diodes by harnessing both singlet and triplet excitons. TADF is facilitated by a small energy difference between the first singlet (S1 ) and triplet (T1 ) excited states (ΔE(ST)), which is minimized by spatial separation of the donor and acceptor moieties. The resultant charge-transfer (CT) excited states are difficult to model using time-dependent density functional theory (TDDFT) because of the delocalization error present in standard density functional approximations to the exchange-correlation energy...
May 17, 2018: Journal of Chemical Theory and Computation
Nicholas J Freeman, Henrik Odéen, Dennis L Parker
PURPOSE: Evaluate a numerical inverse Green's function method of deriving specific absorption rates (SARs) from high intensity focused ultrasound (HIFU) sonications given tissue parameters (thermal conductivity, specific heat capacity, and mass density) and 3-D magnetic resonance imaging (MRI) temperature measurements. METHODS: SAR estimates were evaluated using simulations and MR temperature measurements from HIFU sonications. For simulations, a "true" SAR was calculated using the hybrid angular spectrum method for ultrasound simulations...
May 17, 2018: Medical Physics
Xiaoming Li, Jianhui Zhou, Feifang Hu
Covariate-adaptive designs are widely used to balance covariates and maintain randomization in clinical trials. Adaptive designs for discrete covariates and their asymptotic properties have been well studied in the literature. However, important continuous covariates are often involved in clinical studies. Simply discretizing or categorizing continuous covariates can result in loss of information. The current understanding of adaptive designs with continuous covariates lacks a theoretical foundation as the existing works are entirely based on simulations...
January 1, 2018: Statistical Methods in Medical Research
Youngok Kang, Nahye Cho, Serin Son
The purpose of this study is to analyze how the spatiotemporal characteristics of traffic accidents involving the elderly population in Seoul are changing by time period. We applied kernel density estimation and hotspot analyses to analyze the spatial characteristics of elderly people's traffic accidents, and the space-time cube, emerging hotspot, and space-time kernel density estimation analyses to analyze the spatiotemporal characteristics. In addition, we analyzed elderly people's traffic accidents by dividing cases into those in which the drivers were elderly people and those in which elderly people were victims of traffic accidents, and used the traffic accidents data in Seoul for 2013 for analysis...
2018: PloS One
Wenhui Mi, Alessandro Genova, Michele Pavanello
Since the seminal studies of Thomas and Fermi, researchers in the Density-Functional Theory (DFT) community are searching for accurate electron density functionals. Arguably, the toughest functional to approximate is the noninteracting kinetic energy, Ts [ρ], the subject of this work. The typical paradigm is to first approximate the energy functional and then take its functional derivative, δTs [ρ]δρ(r), yielding a potential that can be used in orbital-free DFT or subsystem DFT simulations. Here, this paradigm is challenged by constructing the potential from the second-functional derivative via functional integration...
May 14, 2018: Journal of Chemical Physics
Yehuda A Ganan, David A Kessler
In this work, we study the problem of front propagation and pattern formation in the stochastic nonlocal Fisher equation. We find a crossover between two regimes: a steadily propagating regime for not too large interaction range and a stochastic punctuated spreading regime for larger ranges. We show that the former regime is well described by the heuristic approximation of the system by a deterministic system where the linear growth term is cut off below some critical density. This deterministic system is seen not only to give the right front velocity, but also predicts the onset of clustering for interaction kernels which give rise to stable uniform states, such as the Gaussian kernel, for sufficiently large cutoff...
April 2018: Physical Review. E
Martin Panholzer, Matteo Gatti, Lucia Reining
The charge-density response of extended materials is usually dominated by the collective oscillation of electrons, the plasmons. Beyond this feature, however, intriguing many-body effects are observed. They cannot be described by one of the most widely used approaches for the calculation of dielectric functions, which is time-dependent density functional theory (TDDFT) in the adiabatic local density approximation (ALDA). Here, we propose an approximation to the TDDFT exchange-correlation kernel which is nonadiabatic and nonlocal...
April 20, 2018: Physical Review Letters
Wiktor Pronobis, Alexandre Tkatchenko, Klaus-Robert Müller
Machine learning (ML) based prediction of molecular properties across chemical compound space is an important and alternative approach to efficiently estimate the solutions of highly complex many-electron problems in chemistry and physics. Statistical methods represent molecules as descriptors that should encode molecular symmetries and interactions between atoms. Many such descriptors have been proposed; all of them have advantages and limitations. Here, we propose a set of general two-body and three-body interaction descriptors which are invariant to translation, rotation and atomic indexing...
May 11, 2018: Journal of Chemical Theory and Computation
Ana Angélica Rêgo de Queiroz, Thaís Zamboni Berra, Maria Concebida da Cunha Garcia, Marcela Paschoal Popolin, Aylana de Souza Belchior, Mellina Yamamura, Danielle Talita Dos Santos, Luiz Henrique Arroyo, Ricardo Alexandre Arcêncio
OBJECTIVES: To describe the epidemiological profile of mortality due to tuberculosis (TB), to analyze the spatial pattern of these deaths and to investigate the temporal trend in mortality due to tuberculosis in Northeast Brazil. METHODS: An ecological study based on secondary mortality data. Deaths due to TB were included in the study. Descriptive statistics were calculated and gross mortality rates were estimated and smoothed by the Local Empirical Bayesian Method...
2018: Revista Latino-americana de Enfermagem
Warangkana Ruckthongsook, Chetan Tiwari, Joseph R Oppong, Prathiba Natesan
BACKGROUND: Maps of disease rates produced without careful consideration of the underlying population distribution may be unreliable due to the well-known small numbers problem. Smoothing methods such as Kernel Density Estimation (KDE) are employed to control the population basis of spatial support used to calculate each disease rate. The degree of smoothing is controlled by a user-defined parameter (bandwidth or threshold) which influences the resolution of the disease map and the reliability of the computed rates...
May 8, 2018: International Journal of Health Geographics
Jefferson E Bates, Niladri Sengupta, Jonathon Sensenig, Adrienn Ruzsinszky
Using a second-order approximation to Random Phase Approximation renormalized (RPAr) many-body perturbation theory for the interacting density-density response function, we have developed a so-called higher-order terms (HOT) approximation for the correlation energy. In combination with the first-order RPAr correction, our new method faithfully captures the infinite-order correlation for a given exchange-correlation kernel, yielding errors of the total correlation energy on the order of 1% or less for most systems...
May 7, 2018: Journal of Chemical Theory and Computation
Mohammad S Farhadinia, Paul J Johnson, David W Macdonald, Luke T B Hunter
Understanding the space use and movement ecology of apex predators, particularly in mosaic landscapes encompassing different land-uses, is fundamental for formulating effective conservation policy. The top extant big cat in the Middle East and the Caucasus, the Persian leopard Panthera pardus saxicolor, has disappeared from most of its historic range. Its spatial ecology in the areas where it remains is almost unknown. Between September 2014 and May 2017, we collared and monitored six adult leopards (5 males and 1 female) using GPS-satellite Iridium transmitters in Tandoureh National Park (355 km2) along the Iran-Turkmenistan borderland...
2018: PloS One
Qingyu Wu, Michael Regan, Hiro Furukawa, David Jackson
Plant shoot systems derive from the shoot apical meristems (SAMs), pools of stems cells that are regulated by a feedback between the WUSCHEL (WUS) homeobox protein and CLAVATA (CLV) peptides and receptors. The maize heterotrimeric G protein α subunit COMPACT PLANT2 (CT2) functions with CLV receptors to regulate meristem development. In addition to the sole canonical Gα CT2, maize also contains three eXtra Large GTP-binding proteins (XLGs), which have a domain with homology to Gα as well as additional domains...
April 30, 2018: PLoS Genetics
Carlos José de Paula Silva, Paula Cristina Pelli Paiva, Liliam Pacheco Pinto de Paula, Jussara de Fátima Barbosa Fonseca, Rafaella Almeida Silvestrini, Marcelo Drummond Naves, Ana Clara Mourão Moura, Efigênia Ferreira E Ferreira
The study investigated the spatial pattern of cases of maxillofacial injury resulting from firearm aggression among teenagers and young adults and analyzed the comparison of income differentials in these areas based on the residence of the victims. This is a cross-sectional study with data from victims attended in three hospitals in Belo Horizonte, State of Minas Gerais, from January 2008 to December 2010. The addresses of the victims were georeferenced by geocoding. Randomness and point density trends were analyzed using Ripley's K function and Kernel maps...
April 2018: Ciência & Saúde Coletiva
Helena Tunstall, Niamh K Shortt, Claire L Niedzwiedz, Elizabeth A Richardson, Richard J Mitchell, Jamie R Pearce
Despite long-term falls in global adult smoking prevalence and over 50 years of tobacco control policies, adolescent smoking persists. Research suggests greater densities of tobacco retail outlets in residential neighbourhoods are associated with higher adolescent smoking rates. Policies to reduce retail outlets have therefore been identified by public health researchers as a potential 'new frontier' in tobacco control. Better understanding of the pathways linking density of tobacco retailers and smoking behaviour could support these policies...
February 5, 2018: Social Science & Medicine
Shan-Shan Zhang, Lei Feng, Ravithree D Senanayake, Christine M Aikens, Xing-Po Wang, Quan-Qin Zhao, Chen-Ho Tung, Di Sun
Due to distinctive quantum confinement effects, ultrasmall gold nanoparticles usually exhibit interesting electronic structure and molecular-like properties. However, the lack of atomically-precise structural information makes the understanding of them almost impossible, such as understanding the relationships between their compositions and unique properties. Herein, by reducing a diphosphine AuI precursor (Au2 (dppm)2 Cl2 ; dppm = Ph2 PCH2 PPh2 ) with or without a S2- releasing reagent, we enriched our knowledge of the members in the families of Au13 and Au8 by the structural determinations of two new dppm-protected gold nanoclusters, [Au13 (dppm)6 ]5+ ( SD/Au1 ) and [Au8 (dppm)4 S2 ]2+ ( SD/Au2 ), respectively...
February 7, 2018: Chemical Science
Ningjing Liu, Hector Aya Parra, Annemieke Pustjens, Kasper Hettinga, Philippe Mongondry, Saskia M van Ruth
Organic products are vulnerable to fraud due to their premium price. Analytical methodology helps to manage the risk of fraud and due to the miniaturization of equipment, tests may nowadays even be rapidly applied on-site. The current study aimed to evaluate portable near infrared spectroscopy (NIRS) in combination with chemometrics to distinguish organic milk from other types of milk, and compare its performance with benchtop NIRS and fatty acid profiling by gas chromatography. The sample set included 37 organic retail milks and 50 non-organic retail milks (of which 36 conventional and 14 green 'pasture' milks)...
July 1, 2018: Talanta
Yaxin Fan, Xinyan Zhu, Bing She, Wei Guo, Tao Guo
The analysis of traffic collisions is essential for urban safety and the sustainable development of the urban environment. Reducing the road traffic injuries and the financial losses caused by collisions is the most important goal of traffic management. In addition, traffic collisions are a major cause of traffic congestion, which is a serious issue that affects everyone in the society. Therefore, traffic collision analysis is essential for all parties, including drivers, pedestrians, and traffic officers, to understand the road risks at a finer spatio-temporal scale...
2018: PloS One
Maggie D Triska, Michael Renton
We investigated how an invading organism's dispersal characteristics affect the efficacy of different surveillance strategies aimed at detecting that organism as it spreads following a new incursion. Specifically, we assessed whether, out of the surveillance strategies tested, the best surveillance strategy for an organism varied depending on the way it disperses. We simulated the spread of invasive organisms with different dispersal characteristics including leptokurtic and non-leptokurtic kernels with different median dispersal distances and degrees of kurtosis...
March 2018: Royal Society Open Science
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