Arbitrary Regions Research Articles

Quantitative Mapping of Intranuclear Diffusion in Living Cells by Phasor Analysis of Local RICS

Image Correlation Spectroscopy (ICS) (Wiseman, Cold Spring Harb. Protoc. 2015) based techniques are quantitative tools for assessing the concentration and dynamics of proteins diffusing in living cells. A wide variety of these methods (ICS, ICCS, RICS, kICS etc.) is applicable to commercial laser scanning microscopes in order to investigate subcellular biophysical properties, for instance the study of protein mobility within the nucleus of eukaryotic cells. Although powerful, these techniques may fail to retrieve a correct value when analyzing inhomogeneous samples, given that no further assumption is made on the specific nature of the inhomogeneity. Being the cell an intrinsically heterogeneous system, a prescreening method for the characterization of the heterogeneity of the system will increase the reliability of ICS techniques for cellular applications.In this respect, we recently introduced a method, based on the phasor analysis of local ICS (PLICS), for extending ICS to heterogeneous systems without the need of a priori assumptions (Scipioni et al., Biophys. J. 2016). The phasor approach, originally developed for the identification of components in fluorescence-lifetime imaging (Digman et al., Biophys. J. 2008), is used within the PLICS algorithm for the analysis of local spatial correlation functions as a fast and unbiased alternative to the fitting procedure. Here we present application of the PLICS concept to Raster Image Correlation Spectroscopy (RICS) (Digman et al., Biophys. J. 2005) for obtaining a map of intra-nuclear diffusion of expressed EGFP in living HeLa cells. The PLICS approach is used to provide a segmentation of the image into sub-regions with homogeneous diffusion coefficient, that is successively quantified by applying Arbitrary Regions Image Correlation Spectroscopy (ARICS) (Hendrix et al., Biophys. J. 2016),a state of the art technique developed for extending the ICS analysis to non-rectangular regions.We believe that PLICS could become a widely used prescreening approach, applicable to several kinds of ICS techniques, for addressing the heterogeneity of a dataset prior to the application of the technique. Furthermore, if the statistics is significant, PLICS is capable of providing an exhaustive mapping over the entire dataset of the property we are willing to measure.

Spatial Distribution of Myxobolus Pethericii and Henneguya Pethericii on the Gills of an African Anabantid Ctenopoma Petherici from the Sange River, Cameroon

The spatial distribution of Myxobolus pethericii Fomena, Lekeufack folefack and Tang II, 2007 and Henneguya pethericii Fomena, Lekeufack folefack and Bouix, 2008 gills parasites of Ctenopoma petherici Gunther, 1864 was investigated. The gill apparatus of each host individual was divided into arbitrary regions and the number of cysts of each parasites species in each gill region was determined. Results were analysed at parasite species and xenocommunity levels. Site specificity was determined by application of Chi-square test to the data. At the same time, mean cyst loads were compared between different gill regions. The mean cyst load of the xenocommunity was higher on arches II and III than on arch IV. M. pethericii encysted more on outer hemibranch of arch IV. The medial segment of the gill was more colonized by M. pethericii and the combination made of M. pethericii+H. pethericii. The greater mean cyst load of M. pethericii was observed on medial segment. The specific preferences of a gill region might be affected by the interaction of factors such as the possible heterogeneity of the gill system, possible differences in the hydrostatic pressure of the bronchial pump and the water current over different parts of the gill surface.

Cloud Detection and Prediction with All Sky Cameras

Atmospheric monitoring is a field of special importance for astroparticle physics, especially for Imaging Atmospheric Cherenkov Telescopes (IACTs) as clouds will absorb and scatter the Cherenkov photons of air showers. Conventional tools used for atmospheric monitoring (e.g. LIDAR) are very expensive and monitor only a small part of the sky at once. Therefore, they are not suitable to perform a wide scan of the sky which is necessary to detect clouds in advance.This article gives a short overview about a method that uses an all sky camera with a 180 ° field of view to identify the cloud distribution by measuring the absorption of star light. It can be used to assign a sky quality rating to single spots, arbitrary regions or the whole sky at once within a 1 min exposure time. A cloud map can be created from the available data that can be used to determine shape and dimension of clouds and to predict their movement. The resulting data can be used by a scheduling algorithm or the operating crew to point the telescope to a different source before the current source gets covered by clouds. The all sky cameras used so far are located on La Palma at the observatory Roque de los Muchachos close to the telescopes FACT and MAGIC and the planned northern CTA site.

Nine‐degrees‐of‐freedom flexmap for a cone‐beam computed tomography imaging device with independently movable source and detector

Couch-mounted cone-beam computed tomography (CBCT) imaging devices with independently rotatable x-ray source and flat-panel detector arms for acquisitions of arbitrary regions of interest (ROI) have recently been introduced in image-guided radiotherapy (IGRT). This work analyzes mechanical limitations and gravity-induced effects influencing the geometric accuracy of images acquired with arbitrary angular constellations of source and detector in nonisocentric trajectories, which is considered essential for IGRT. In order to compensate for geometric inaccuracies of this modality, a 9-degrees-of-freedom (9-DOF) flexmap correction approach is presented, focusing especially on the separability of the flexmap parameters of the independently movable components of the device. The 9-DOF comprise a 3D translation of the x-ray source focal spot, a 3D translation of the flat-panel's active area center and three Euler-rotations of the detector's row and column vectors. The flexmap parameters are expressed with respect to the angular position of each of the devices arms. Estimation of the parameters is performed, using a CT-based structure set of a table-mounted, cylindrical ball-bearing phantom. Digitally reconstructed radiograph (DRR) patches are derived from the structure set followed by local 2D in-plane registration and subsequent 3D transform estimation by nonlinear regression with outlier detection. Flexmap parameter evaluations for the factory-calibrated system in clockwise and counter-clockwise rotation direction have shown only minor differences for the overall set of flexmap parameters. High short-term reproducibility of the flexmap parameters has been confirmed by experiments over 10 acquisitions for both directions, resulting in standard deviation values of ≤0.183mm for translational components and ≤0.0219deg for rotational components, respectively. A comparison of isocentric and nonisocentric flexmap evaluations showed that the mean differences of the parameter curves reside within their standard deviations, confirming the ability of the proposed calibration method to handle both types of trajectories equally well. Reconstructions of 0.1mm and 0.25mm steel wires showed similar results for the isocentric and nonisocentric cases. The full-width at half maximum (FWHM) measure indicates an average improvement of the calibrated reconstruction of 85% over the uncalibrated reconstruction. The contrast of the point spread function (PSF) improved by 310% on average over all experiments. Moreover, a reduced amount of artifacts visible in nonisocentric reconstructions of a head phantom and a line-pair phantom has been achieved by separate application of the 9-DOF flexmap on the geometry described by the independently moving source arm and detector arm. Using a 9-DOF flexmap approach for correcting the geometry of projections acquired with a device capable of independent movements of the source and panel arms has been shown to be essential for IGRT use cases such as CBCT reconstruction and 2D/3D registration tasks. The proposed pipeline is able to create flexmap curves which are easy to interpret, useful for mechanical description of the device and repetitive quality assurance as well as system-level preventive maintenance. Application of the flexmap has shown improvements of image quality for planar imaging and volumetric imaging which is crucial for patient alignment accuracy.

PREDICTION OF SOLAR FLARES USING UNIQUE SIGNATURES OF MAGNETIC FIELD IMAGES

ABSTRACT Prediction of solar flares is an important task in solar physics. The occurrence of solar flares is highly dependent on the structure and topology of solar magnetic fields. A new method for predicting large (M- and X-class) flares is presented, which uses machine learning methods applied to the Zernike moments (ZM) of magnetograms observed by the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory for a period of six years from 2010 June 2 to 2016 August 1. Magnetic field images consisting of the radial component of the magnetic field are converted to finite sets of ZMs and fed to the support vector machine classifier. ZMs have the capability to elicit unique features from any 2D image, which may allow more accurate classification. The results indicate whether an arbitrary active region has the potential to produce at least one large flare. We show that the majority of large flares can be predicted within 48 hr before their occurrence, with only 10 false negatives out of 385 flaring active region magnetograms and 21 false positives out of 179 non-flaring active region magnetograms. Our method may provide a useful tool for the prediction of solar flares, which can be employed alongside other forecasting methods.

Transversely isotropic half-spaces subject to surface pressures

We outline a general methodology for proving the equivalence between several solutions available in the literature for the elastic problem of transversely isotropic materials. The proposed methodology is mathematically supported by a novel solution strategy yet arriving at the same expression of the displacement field contributed by Ding et al. (2006).We further show how to address the case of transversely isotropic half-spaces subject to linearly distributed vertical pressures applied over arbitrary regions of the half-space boundary. In the significant case of polygonal regions, displacements and stresses at arbitrary points of the half-space are evaluated analytically and the relevant singularities are properly accounted for.The proposed approach has been numerically validated by first solving a basic indentation problem for which an analytical expression of the displacements on the half-space surface is available. Furthermore, the displacement and stress fields induced in a half-space by a polygonal indenter of arbitrary shape subject to a prescribed vertical displacement is illustrated by means of representative contour plots.

Aproksymacja zagadnienia Dirichleta siatką nierównomierną na brzegu

The author describes a construction of the positive difference scheme, which is the approximation of the Dirichlet problem for an elliptic second order equation with mixed derivatives in an arbitrary region in R2. The a priori estimation for the approximate solution is proved and the estimation of the rate of convergence in maximum norm is established.

Weak-form collocation – A local meshless method in linear elasticity

This paper is concerned with the formulation of local meshfree methods, for the solution of two-dimensional problems in linear elasticity, in the framework of the theory of structures.Local meshfree methods are derived through a weighted-residual formulation which leads to a local weak form that is the well known work theorem of the theory of structures. In an arbitrary local region, the work theorem establishes an energy relationship between a statically-admissible stress field and an independent kinematically-admissible strain field. Based on the independence of these two fields, this paper presents two new meshless formulations that aim a reduction of the computational effort. While in the first formulation the local form of the work theorem is reduced to regular boundary terms only, in the second formulation the local form of the work theorem is simply an integration-free formula.The moving least squares (MLS) approximation of the elastic field is used in this paper to implement both local meshless formulations.Several problems were analyzed with these techniques, in order to assess the accuracy and efficiency of the formulations. The results obtained in this work are in perfect agreement with those of the available analytical solutions. The accuracy and efficiency of the integration-free formulation make this a reliable and robust local meshfree method, generated in the framework of the theory of structures.

An energy-efficient query based on variable region for large-scale smart grid

The state-of-the-art query techniques in power grid monitoring systems focus on querying history data, which typically introduces an unwanted lag when the systems try to discover emergency situations. The monitoring data of large-scale smart grids are massive, dynamic and highly dimensional, so global query, the method widely adopted in continuous queries in Wireless Sensor Networks (WSN), is rendered not suitable for its high energy consumption. The situation is even worse with increasing application complexity. We propose an energy-efficient query technique for large-scale smart grids based on variable regions. This method can query an arbitrary region based on variable physical windows, and optimizes data retrieve paths by a key nodes selection strategy. According to the characteristics of sensing data, we introduce an efficient filter into the each query subtree to keep non-skyline data from being retrieved. Experimental results show that our method can efficiently return the overview situation of any query region. Compared to TAG and ESA, the average query efficiency of our approach is improved by 79% and 46%, respectively; the total energy consumption of regional query is decreased by 82% and 50%, respectively.

방향성 공간적 조건부 자기회귀 모형의 베이즈 분석 방법

공간통계 방법 중 지역에 대한 어떤 집합체 자료나 평균자료들을 분석하는데 일반적으로 공간적 자기회귀 (conditionally autoregressive) 모형을 사용한다. 공간적 자기회귀 모형에 정의되는 공간적 이웃 소지역들은 중점의 거리나 근접성으로 정의된다. Kyung과 Ghosh (2009)는 방향에 따라서 이웃간 자기상관성의 크기가 다른 확장된 공간 모형을 제시하였다. 제안된 방향적 조건부 자기회귀 (directional conditionally autoregressive) 모형은 고유 이방성을 모형화하여 기존의 CAR과정을 일반화한다. 제시한 방향적 조건부 자기회귀모형의 모수추정으로 마르코프 체인 몬테 카를로 방법을 기반으로 한 베이즈 추정법을 제시한다. 제시한 모형을 스코틀랜드 그레이터 글래스고우의 로그변환된 부동산 가격에 적용하여 조건부 자기회귀모형과 비교하였다. Counts or averages over arbitrary regions are often analyzed using conditionally autoregressive (CAR) models. The spatial neighborhoods within CAR model are generally formed using only the inter-distance or boundaries between the sub-regions. Kyung and Ghosh (2009) proposed a new class of models to accommodate spatial variations that may depend on directions, using different weights given to neighbors in different directions. The proposed model, directional conditionally autoregressive (DCAR) model, generalized the usual CAR model by accounting for spatial anisotropy. Bayesian inference method is discussed based on efficient Markov chain Monte Carlo (MCMC) sampling of the posterior distributions of the parameters. The method is illustrated using a data set of median property prices across Greater Glasgow, Scotland, in 2008.

Adaptive fuzzy prescribed performance controller design for a class of uncertain fractional-order nonlinear systems with external disturbances

A fractional-order adaptive fuzzy controller, capable of guaranteeing prescribed performance, is designed for a class of uncertain fractional-order nonlinear systems with external disturbances in this paper. With respect to the prescribed performance control, we mean that the system variables converge to an arbitrary small region of the origin with convergence rate no less than a certain prescribed function. Fuzzy logic system is utilized to approximate an unknown nonlinear function which contains fractional-order terms. Based on the Lyapunov stability criterion, a fractional-order adaptive fuzzy sliding mode controller, which can guarantee the stability of the closed-loop system as well as the prescribed performance, is constructed. Finally, simulation results are given to confirm our results.

Three-dimensional pore geometry and permeability anisotropy of Berea sandstone under hydrostatic pressure: connecting path and tortuosity data obtained by microfocus X-ray CT

Abstract Void space and permeability are two primary factors controlling the movement and storage of fluids in rock and sediments. To investigate fluid flow anisotropy in Berea sandstone, permeability was measured in three perpendicular directions under effective confining pressure as a function of pore pressure. Permeability anisotropy was observed slightly in the normal and in two parallel directions to the bedding planes. We introduced microfocus X-ray computed tomography (CT) as a non-destructive tool and the three-dimensional medial axis (3DMA) method to quantify the flow-relevant geometric properties of the voids structure. Using this apparatus and structure analysis software, we obtained the distributions of pore size, throat size and the number of connecting paths between two faces in an arbitrary region of Berea sandstone. Using these data, we also evaluated the number of connecting paths between two faces and tortuosity within an arbitrary region, and discussed the relationship between permeability anisotropy and voids geometry.

Parallel adaptive event horizon finder for numerical relativity

With Advanced LIGO detecting the gravitational waves emitted from a pair of merging black holes in late 2015, we have a new perspective into the strong field regime of binary black hole systems. Event horizons are the defining features of such black hole spacetimes. We introduce a new code for locating event horizons in numerical simulations based on a Delaunay triangulation on a topological sphere. The code can automatically refine arbitrary regions of the event horizon surface to find and explore features such as the hole in a toroidal event horizon, as discussed in our companion paper. We also investigate various ways of integrating the geodesic equation and find evolution equations that can be integrated efficiently with high accuracy.

The gravity duals of modular Hamiltonians

In this work, we investigate modular Hamiltonians defined with respect to arbitrary spatial regions in quantum field theory states which have semi-classical gravity duals. We find prescriptions in the gravity dual for calculating the action of the modular Hamiltonian on its defining state, including its dual metric, and also on small excitations around the state. Curiously, use of the covariant holographic entanglement entropy formula leads us to the conclusion that the modular Hamiltonian, which in the quantum field theory acts only in the causal completion of the region, does not commute with bulk operators whose entire gauge-invariant description is space-like to the causal completion of the region.

Nucleation of magnetic bubble domains in iron garnet films by means of an electric probe

The possibility of the local nucleation of magnetic bubble domains from a single-domain state in an arbitrary region of a iron garnet film ((210) crystallographic orientation) by means of an electrically charged tip electrode has been experimentally demonstrated. The size of magnetic bubble domains nucleated near the contact point between the probe and sample depends on the magnitude of a DC voltage supplied to the probe. After the removal of the voltage, magnetic bubble domains move away from the probe, decreasing to the equilibrium radius.

Fundamentals of the route theory for satellite constellation design for Earth discontinuous coverage. Part 1: Analytic emulation of the Earth coverage

This paper opens a series of articles expounding the fundamentals of the route theory for satellite constellation design for Earth discontinuous coverage. In Part 1 of the series the analytical model for Earth coverage by satellites’ swath conforming to the essential of discontinuous coverage, in contrast to continuous coverage, is presented. The analytic relations are consecutively derived for calculation of single- and multi-satellite Earth surface latitude coverage as well as for generating full set of typical satellite visibility zone time streams realized in the repeating latitude coverage pattern for given arbitrary satellite constellation. The analytic relations mentioned are used for developing the method for analysis of discontinuous coverage of fixed arbitrary Earth region for given satellite constellation using both deterministic and stochastic approaches. The method provides analysis of the revisit time for given satellite constellation, as a result of high speed (fractions of a second or seconds) computer calculations in a wide range of possible revisit time variations for different practical purposes with high accuracy which is at least on par with that provided by known numerical simulating methods based on direct modeling of the satellite observation mission, or in a number of cases is even superior to it.

Simulation of measuring data obtained from RFID-tags in systems of spatial localization of objects

Paper presents the simulation of processes of spatial localization of objects using systems of radio-frequency identification (RFID systems). The simulation technique for simulation modeling the measuring data of proximity type, received signal strength (RSS) type, and read rate (RR) type obtained from passive RFID-tags has been developed. The technique allows us to carry out the preliminary comparison of localization accuracy ensured in case of using different algorithms of localization and types of measuring data for arbitrary regions of localization. The testing of this technique indicated that the relative error of simulation results as compared to experimental results amounted on average to 8% and did not exceed 28%.

An Image Processing Workflow to Quantify Penetration of Blob-like Structures into an Arbitrary Region of Interest

An Image Processing Workflow to Quantify Penetration of Blob-like Structures into an Arbitrary Region of Interest

Entanglement entropy from one-point functions in holographic states

For holographic CFT states near the vacuum, entanglement entropies for spatial subsystems can be expressed perturbatively as an expansion in the one-point functions of local operators dual to light bulk fields. Using the connection between quantum Fisher information for CFT states and canonical energy for the dual spacetimes, we describe a general formula for this expansion up to second-order in the one-point functions, for an arbitrary ball-shaped region, extending the first-order result given by the entanglement first law. For two-dimensional CFTs, we use this to derive a completely explicit formula for the second-order contribution to the entanglement entropy from the stress tensor. We show that this stress tensor formula can be reproduced by a direct CFT calculation for states related to the vacuum by a local conformal transformation. This result can also be reproduced via the perturbative solution to a non-linear scalar wave equation on an auxiliary de Sitter spacetime, extending the first-order result in arXiv/1509.00113.

Event-Driven Control for Networked Control Systems With Quantization and Markov Packet Losses

In this paper, event-driven is used in a networked control system (NCS) which is subjected to the effect of quantization and packet losses. A discrete event-detector is used to monitor specific events in the NCS. Both an arbitrary region quantizer and Markov jump packet losses are also considered for the NCS. Based on zoom strategy and Lyapunov theory, a complete proof is given to guarantee mean square stability of the closed-loop system. Stabilization of the NCS is ensured by designing a feedback controller. Lastly, an inverted pendulum model is given to show the advantages and effectiveness of the proposed results.