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Spatial modeling

María V Cardo, Alejandra Rubio, Melania Junges, Darío Vezzani, Aníbal E Carbajo
Given their medical and veterinary relevance, the members of the Pipiens Assemblage are a worldwide target of ecological research. The distribution of Culex pipiens s.s. and Cx. quinquefasciatus converge in Buenos Aires, Argentina, where hybrids have been detected. Each member of the assemblage exhibits a distinct eco-physiological behaviour that can affect its efficiency in pathogen transmission. Our aim was to identify the environmental drivers for the spatio-temporal distribution of each member, focusing on latitudinal and urbanisation gradients...
October 24, 2016: Memórias do Instituto Oswaldo Cruz
Chao Wu, Xinyue Ye, Fu Ren, You Wan, Pengfei Ning, Qingyun Du
Housing is among the most pressing issues in urban China and has received considerable scholarly attention. Researchers have primarily concentrated on identifying the factors that influence residential property prices and how such mechanisms function. However, few studies have examined the potential factors that influence housing prices from a big data perspective. In this article, we use a big data perspective to determine the willingness of buyers to pay for various factors. The opinions and geographical preferences of individuals for places can be represented by visit frequencies given different motivations...
2016: PloS One
Natalia A Dellabianca, Graham J Pierce, Andrea Raya Rey, Gabriela Scioscia, David L Miller, Mónica A Torres, M Natalia Paso Viola, R Natalie P Goodall, Adrián C M Schiavini
Commerson's dolphins (Cephalorhynchus c. commersonii) and Peale's dolphins (Lagenorhynchus australis) are two of the most common species of cetaceans in the coastal waters of southwest South Atlantic Ocean. Both species are listed as Data Deficient by the IUCN, mainly due to the lack of information about population sizes and trends. The goal of this study was to build spatially explicit models for the abundance of both species in relation to environmental variables using data collected during eight scientific cruises along the Patagonian shelf...
2016: PloS One
Eileen K Jaffe
Porphobilinogen synthase (PBGS), also known as 5-aminolevulinate dehydratase, is an essential enzyme in the biosynthesis of all tetrapyrroles, which function in respiration, photosynthesis, and methanogenesis. Throughout evolution, PBGS adapted to a diversity of cellular niches and evolved to use an unusual variety of metal ions both for catalytic function and to control protein multimerization. With regard to the active site, some PBGSs require Zn(2+); a subset of those, including human PBGS, contain a constellation of cysteine residues that acts as a sink for the environmental toxin Pb(2+)...
October 26, 2016: Accounts of Chemical Research
Hanns Moshammer, Stana Simic, Daniela Haluza
Ultra-Violet (UV) radiation covers the spectrum of wavelengths from 100 to 400 nm. The potency and biological activity for a variety of endpoints differ by wavelength. For monitoring and communication purposes, different UV action spectra have been developed. These spectra use different weighting functions. The action spectrum for erythemal dose is the most widely used one. This erythemal dose per time or dose-rate has been further simplified into a "UV index". Following this example, in our review we use the term "index" or (plural) "indices" in a more general description for all simplified single-value measures for any biologically effective UV dose, e...
October 24, 2016: International Journal of Environmental Research and Public Health
George A Prenosil, Bernd Klaeser, Michael Hentschel, Markus Fürstner, Michael Berndt, Thomas Krause, Thilo Weitzel
PURPOSE: A PET/CT system's imaging capabilities are best described by its point spread function (PSF) in the spatial domain or equivalently by its modulation transfer function (MTF) in the spatial frequency domain. Knowing PSFs or MTFs is a prerequisite for many numerical methods attempting to improve resolution and to reduce the partial volume effect. In PET/CT, the observed PSF is a convolution of the system's intrinsic imaging capabilities including image reconstruction (PSF0) and the positron range function (PRF) of the imaged β(+) emitting isotope...
October 2016: Medical Physics
B P MacLeod, J E Hoffman, S A Burke, D A Bonn
Measurement instruments and fabrication tools with spatial resolution on the atomic scale require facilities that mitigate the impact of vibration sources in the environment. One approach to protection from vibration in a building's foundation is to place the instrument on a massive inertia block, supported on pneumatic isolators. This opens the questions of whether or not a massive floating block is susceptible to acoustic forces, and how to mitigate the effects of any such acoustic buffeting. Here this is investigated with quantitative measurements of vibrations and sound pressure, together with finite element modeling...
September 2016: Review of Scientific Instruments
John R Kirtley, Lisa Paulius, Aaron J Rosenberg, Johanna C Palmstrom, Connor M Holland, Eric M Spanton, Daniel Schiessl, Colin L Jermain, Jonathan Gibbons, Y-K-K Fung, Martin E Huber, Daniel C Ralph, Mark B Ketchen, Gerald W Gibson, Kathryn A Moler
Superconducting QUantum Interference Device (SQUID) microscopy has excellent magnetic field sensitivity, but suffers from modest spatial resolution when compared with other scanning probes. This spatial resolution is determined by both the size of the field sensitive area and the spacing between this area and the sample surface. In this paper we describe scanning SQUID susceptometers that achieve sub-micron spatial resolution while retaining a white noise floor flux sensitivity of ≈2μΦ0/Hz(1/2). This high spatial resolution is accomplished by deep sub-micron feature sizes, well shielded pickup loops fabricated using a planarized process, and a deep etch step that minimizes the spacing between the sample surface and the SQUID pickup loop...
September 2016: Review of Scientific Instruments
David R Jacobson, Omar A Saleh
High spatial and temporal resolution magnetic tweezers experiments allow for the direct calibration of pulling forces applied to short biomolecules. In one class of experiments, a force is applied to a structured RNA or protein to induce an unfolding transition; when the force is maintained at particular values, the molecule can exhibit conformational switching between the folded and unfolded states or between intermediate states. Here, we analyze the degree to which common force calibration approaches, involving the fitting of model functions to the Allan variance or power spectral density of the bead trajectory, are biased by this conformational switching...
September 2016: Review of Scientific Instruments
Alexander W Peterson, Michael Halter, Anne L Plant, John T Elliott
Surface plasmon resonance (SPR) imaging allows real-time label-free imaging based on index of refraction and changes in index of refraction at an interface. Optical parameter analysis is achieved by application of the Fresnel model to SPR data typically taken by an instrument in a prism based figuration. We carry out SPR imaging on a microscope by launching light into a sample and collecting reflected light through a high numerical aperture microscope objective. The SPR microscope enables spatial resolution that approaches the diffraction limit and has a dynamic range that allows detection of subnanometer to submicrometer changes in thickness of biological material at a surface...
September 2016: Review of Scientific Instruments
Roger F Loring
Optically detected single-turnover measurements of biological and inorganic catalysts provide a detailed picture of structural and dynamical influences on catalytic activity. Measurement at the single-molecule level of catalysis of a fluorogenic reaction (or its reverse) yields a stochastic fluorescence trajectory reflecting the statistics of individual reaction and product dissociation events. Analysis of time correlations displayed by this trajectory reveals reaction details inaccessible in a bulk measurement of averaged dynamics...
October 7, 2016: Journal of Chemical Physics
Peter Hamm
With the help of a Markov State Model (MSM), two-state behaviour is resolved for two computer models of water in a temperature range from 255 K to room temperature (295 K). The method is first validated for ST2 water, for which the so far strongest evidence for a liquid-liquid phase transition exists. In that case, the results from the MSM can be cross-checked against the radial distribution function g5(r) of the 5th-closest water molecule around a given reference water molecule. The latter is a commonly used local order parameter, which exhibits a bimodal distribution just above the liquid-liquid critical point that represents the low-density form of the liquid (LDL) and the high density liquid...
October 7, 2016: Journal of Chemical Physics
Matthias Baumann, Ignacio Gasparri, María Piquer-Rodríguez, Gregorio Gavier Pizarro, Patrick Griffiths, Patrick Hostert, Tobias Kuemmerle
Carbon emissions from land-use changes in tropical dry forest systems are poorly understood, although they are likely globally significant. The South American Chaco has recently emerged as a hot spot of agricultural expansion and intensification, as cattle ranching and soybean cultivation expand into forests, and as soybean cultivation replaces grazing lands. Still, our knowledge of the rates and spatial patterns of these land-use changes and how they affected carbon emissions remains partial. We used the Landsat satellite image archive to reconstruct land-use change over the past 30 years and applied a carbon bookkeeping model to quantify how these changes affected carbon budgets...
October 26, 2016: Global Change Biology
Masahiro Tanoue, Yukiko Hirabayashi, Hiroaki Ikeuchi
The impacts of flooding are expected to rise due to population increases, economic growth and climate change. Hence, understanding the physical and spatiotemporal characteristics of risk drivers (hazard, exposure and vulnerability) is required to develop effective flood mitigation measures. Here, the long-term trend in flood vulnerability was analysed globally, calculated from the ratio of the reported flood loss or damage to the modelled flood exposure using a global river and inundation model. A previous study showed decreasing global flood vulnerability over a shorter period using different disaster data...
October 26, 2016: Scientific Reports
Janusz Gajda, Marek Stencel
This paper concerns a special type of eddy-current sensor in the form of inductive loops. Such sensors are applied in the measuring systems classifying road vehicles. They usually have a rectangular shape with dimensions of 1 × 2 m, and are installed under the surface of the traffic lane. The wide Point Spread Function (PSF) of such sensors causes the information on chassis geometry, contained in the measurement signal, to be strongly averaged. This significantly limits the effectiveness of the vehicle classification...
October 4, 2016: Sensors
K Yu Arutyunov, A Ramos-Álvarez, A V Semenov, Yu P Korneeva, P P An, A A Korneev, A Murphy, A Bezryadin, G N Gol'tsman
The topic of superconductivity in strongly disordered materials has attracted significant attention. These materials appear to be rather promising for fabrication of various nanoscale devices such as bolometers and transition edge sensors of electromagnetic radiation. The vividly debated subject of intrinsic spatial inhomogeneity responsible for the non-Bardeen-Cooper-Schrieffer relation between the superconducting gap and the pairing potential is crucial both for understanding the fundamental issues of superconductivity in highly disordered superconductors, and for the operation of corresponding nanoelectronic devices...
November 25, 2016: Nanotechnology
Athanasios Athanasiadis, Clare Fitzgerald, Nicholas M Davidson, Chiara Giorio, Stanley W Botchway, Andrew D Ward, Markus Kalberer, Francis D Pope, Marina K Kuimova
Organic aerosols (OAs) play important roles in multiple atmospheric processes, including climate change, and can impact human health. The physico-chemical properties of OAs are important for all these processes and can evolve through reactions with various atmospheric components, including oxidants. The dynamic nature of these reactions makes it challenging to obtain a true representation of their composition and surface chemistry. Here we investigate the microscopic viscosity of the model OA composed of squalene, undergoing chemical aging...
October 26, 2016: Physical Chemistry Chemical Physics: PCCP
Erik C B Johnson, Jing Kang
A small molecule named ISRIB has recently been described to enhance memory in rodents. In this study we aimed to test whether ISRIB would reverse learning and memory deficits in the J20 mouse model of human amyloid precursor protein (hAPP) overexpression, a model that simulates many aspects of Alzheimer's disease in which memory deficits are a hallmark feature. We did not observe a significant rescue effect with ISRIB treatment on spatial learning and memory as assessed in the Morris water maze in J20 mice...
2016: PeerJ
Yanlong Guo, Haiyan Wei, Chunyan Lu, Bei Gao, Wei Gu
Climate change will significantly affect plant distribution as well as the quality of medicinal plants. Although numerous studies have analyzed the effect of climate change on future habitats of plants through species distribution models (SDMs), few of them have incorporated the change of effective content of medicinal plants. Schisandra sphenanthera Rehd. et Wils. is an endangered traditional Chinese medical plant which is mainly located in the Qinling Mountains. Combining fuzzy theory and a maximum entropy model, we obtained current spatial distribution of quality assessment for S...
2016: PeerJ
Lauren M Woods, Elizabeth G Biro, Muxi Yang, Kevin G Smith
The effects of disturbance on local species diversity have been well documented, but less recognized is the possibility that disturbances can alter diversity at regional spatial scales. Since regional diversity can dictate which species are available for recolonization of degraded sites, the loss of diversity at regional scales may impede the recovery of biodiversity following a disturbance. To examine this we used a chemical disturbance of rotenone, a piscicide commonly used for fish removal in aquatic habitats, on small fishless freshwater ponds...
2016: PeerJ
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