Partition Step Research Articles

Isolation and identification of microplastic on the cockleshell of blood clam (Anadara Granosa Linn)

This study aims to figure out the occurrence of microplastics in cockleshells of Anadara granosa Liin from the five beaches. The dried cockleshells were immersed in NaCl for the partition step in view of the particular gravity of the microplastic and categorized according to shape under a stereo microscope. In all samples, were consistently found microplastics. The beach that has the largest abundance of microplastics is the Kenjeran Beach Surabaya in East Java Province. The shape of the abundance of microplastics found in this research were fragments, film, foams, crystals, granules, pellets, filaments, and yarn. The average microplastic abundance was 171 pieces per 75 grams of cockleshell dry weight. Among the identified microplastics, fragment (55.33%) was the most frequent type. The occurrence and distribution of microplastics in cockleshells of specimens from the studied region provided information for evaluating the risks of microplastics.

A novel monotone finite volume element scheme for diffusion equations

We present a novel monotone finite volume element scheme for the diffusion problem on triangular grids. Firstly, one fictitious triangular element is introduced for each edge of any element, and another vertex of this fictitious element is on the outward extended straight line passing through two points: The vertex opposite to this edge and the barycenter of the element. The diffusive tensor and the solution in this element are continuously extended to its corresponding fictitious element. The fictitious element and the continuous extension not only avoid the phenomenon that the control volume segment passes through other elements, but also are helpful to the construction and theoretical analysis for our monotone scheme. Secondly, one new nonlinear two-point flux formulation is obtained for some part control volume edge whose another endpoint is the barycenter of the fictitious element, and this straight segment crosses through the common edge of the triangular element and its fictitious one. The approximation of κ∇u on this straight control volume edge is constructed by some weighted average with the gradients of two finite element functions, and the weighted coefficients are determined by the nonlinear two-point flux idea. Furthermore, we proved that the new scheme is monotone under some conditions: the diffusion tensor and exact solution functions are properly smooth, and the partition step size h is properly small, and the solutions on three nodes of any element are not nonnegative, and furthermore not simultaneously zero, and the nodes of the fictitious element are properly chosen. We also proved that the corresponding coefficient matrix is of M-matrix. Finally, we carry on some typical experiments. Numerical results verify the monotonicity of this new scheme, and confirm its accuracy and stability.

Determination of Avermectins Residues in Soybean, Bean, and Maize Using a QuEChERS-Based Method and Ultra-High-Performance Liquid Chromatography Coupled to Tandem Mass Spectrometry

Soybean, maize, and bean are crops of great economic importance, but in recent years have suffered with infestations of the caterpillar Helicoverpa armigera, with the main reason being the resistance of this pest to most pesticides. Avermectin emamectin benzoate was recently released to control this pest. Other avermectins, like abamectin, doramectin, eprinomectin, and ivermectin are used in large scale because they potent acaricidal, anthelmintic, and insecticidal activities. Thus, a simple and fast method for the determination of avermectins in these crops based on a quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction procedure and ultra-high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) analysis was developed and validated. For extraction, water followed by acetonitrile:isopropanol and a partition step with salts was stablished. With the clean-up step using activated EMR-Lipid, limits of detection of 1.2 μg kg−1 for abamectin, doramectin, emamectin benzoate, and ivermectin, and of 2.4 μg kg−1 for eprinomectin were achieved. The validation showed satisfactory results and the method was successfully applied to commercial samples, indicating that it is suitable for routine analysis.

Multi-sensor Multiple Maneuvering Targets Tracking Algorithm under Greedy Measurement Partitioning Mechanism

A novel method Interacting Multiple Mode Multi-Sensor Multi-target Multi-Bernoulli (IMM-MS-MeMBer) filter to track multiple maneuvering targets in low detection probability scenario is proposed. At the prediction stage of the IMM-MS-MeMBer filter, model probability of the target is adaptively updated by utilizing the current measurement information, and then the mixed prediction of the target state is executed; At the update stage of the IMM-MS-MeMBer filter, the greedy multi-sensor measurement partitioning strategy is employed in measurement partition step, the posterior probability density of the target is updated by using the divided set of measurements and the IMM-MS-MeMBer filter; In addition, the IMM-MS-MeMBer filter utilizes the target angle and Doppler information to realize the simultaneous estimation of the position and speed of multiple maneuvering targets. Numerical experiments verify the superior performance of the IMM-MS-MeMBer filter.

The Variational Iterations Method for the Three-dimensional Equations Analysis of Mathematical Physics and the Solution Visualization with its Help

The aim of the work is to use the variational iterations method to study the three-dimensional equations of mathematical physics and visualize the solutions obtained on its basis and the 3DsMAX software package. An analytical solution of the three-dimensional Poisson equations is obtained for the first time. The method is based on the Fourier idea of variables separation with the subsequent application of the Bubnov-Galerkin method for reducing partial differential equations to ordinary differential equations, which in the Western scientific literature has become known as the generalized Kantorovich method, and in the Eastern European literature has known as the variational iterations method. This solution is compared with the numerical solution of the three-dimensional Poisson equation by the finite differences method of the second accuracy order and the finite element method for two finite element types: tetrahedra and cubic elements, which is a generalized Kantorovich method, based on the solution of the three-dimensional stationary differential heat equation. As the method study, a set of numerical methods was used. For the results reliability, the convergence of the solutions by the partition step is checked. The results comparison with a change in the geometric parameters of the heat equation is made and a conclusion is drawn on the solutions reliability obtained. Solutions visualization using the 3Ds max program is also implemented.

Characterization and Prevalence of Campylobacter spp. From Broiler Chicken Rearing Period to the Slaughtering Process in Eastern China.

Campylobacter is one of the most important foodborne pathogens worldwide, and poultry is regarded as the main reservoir of Campylobacter. The contamination of Campylobacter in broiler chickens at the farm level is closely related to the transmission of Campylobacter in the poultry production chain. This study identified 464 Campylobacter isolates from 1,534 samples from broiler rearing period and slaughtering process including 233 Campylobacter jejuni isolates and 231 Campylobacter coli isolates. We have observed a dynamic distribution of Campylobacter during broiler chicken production, that 66.3% of Campylobacter isolates were C. jejuni during broiler rearing period, while C. coli occupied 60.4% of Campylobacter isolates during the broiler slaughtering process. A tag-label method allowed us to track the dynamic of Campylobacter in each broiler chicken from 31-day age at rearing to the partition step in the slaughterhouse. At the 31-day during rearing, 150 broiler chicken were labeled, and was tracked for Campylobacter positive from rearing period to slaughtering process. Among the labeled broiler, 11 of the tracking broiler samples were able to detect Campylobacter from rearing period to slaughtering. All Campylobacter isolates from the 11 tracking samples were sequenced and analyzed. C. jejuni isolates were divided into four STs and C. coli isolates were divided into six STs. Isolates with identical core genome were observed from the same tag-labeled samples at different stages indicating a vertical transmission of Campylobacter in the early broiler meat production. Meanwhile, the core genome analysis elucidated the cross-contamination of Campylobacter during the rearing period and the slaughtering process. The virulotyping analysis revealed that all C. jejuni isolates shared the same virulotypes, while C. coli isolates were divided into three different virulotypes. The antimicrobial resistance gene analysis demonstrated that all Campylobacter isolates contained at least two antibiotic resistance genes (ARGs), and the ARG profiles were well-corresponding to each ST type. Our study observed a high prevalence of Campylobacter during the early chicken meat production, and further studies will be needed to investigate the diversity and transmission of Campylobacter in the poultry production chain.

Anaerobic digestion of purple phototrophic bacteria – The release step of the partition-release-recover concept

Purple phototrophic bacteria (PPB) have been proposed as a high-growth, assimilative option for wastewater treatment. The original partition-release-recover concept proposal requires their near complete digestion and release (and subsequent recovery) of energy and nutrients in an anaerobic digester. While the growth (partition) step has been extensively assessed, no work has been done on their anaerobic digestion characteristics (release). Continuous mesophilic (20d) and thermophilic (10d) digestion could achieve around 55% volatile solids degradation (VSD), with 35% (mesophilic) and 20% (thermophilic) nitrogen solubilisation. Post digestion (with/without pretreatment) could increase the VSD to 70% and nitrogen solubilisation to 43%. A number of pretreatment options were tested, with high temperature and sonication being relatively effective, and chemical treatment, and temperature phased digestion being relatively ineffective vs controls. Overall, anaerobic digestion of PPB results in substantial residual particulate material, with an increased nitrogen content, and avenues to effectively utilise this residue should be identified.

CUDA implementation of fractal image compression

Fractal coding is a lossy image compression technique, which encodes the image in a way that would require less storage space using the self-similar nature of the image. The main drawback of fractal compression is the high encoding time. This is due to the hard task of finding all fractals during the partition step and the search for the best match of fractals. Lately, GPUs (Graphical Processing Unit) have been exploited to implement fractal image compression algorithms due to their high computational power. The prime aim of this paper is to design and implement a parallel version of the Fisher classification scheme using CUDA to exploit the computational power available in the GPUs. Fisher classification scheme is used to reduce the encoding time of fractal images by limiting the search for the best match of fractals. Encoding time, compression ratio and peak signal-to-noise ratio was used as metrics to assess the correctness and the performance of the developed algorithm. Eight images with different sizes (512 × 512, 1024 × 1024 and 2048 × 2048) have been used for the experiments. The conducted experiments showed that a speedup of 6.4 × was achieved in some images using NVIDIA GeForce GT 660 M GPU.

Partition‐composition method for online detection of interconnected power system transient stability

A new partition-composition method for online detection of transient stability of interconnected power system with the data from wide area measurement system (WAMS) is proposed. It consists of two parts: partition and composition. In the partition step, interconnected grids are divided into several local areas according to their geographical locations or ownership. Each area is modelled as an adjoint power system (APS) to determine its own synchronism. In the composition step, transient stability of entire grid is evaluated by the APS model of entire system composed with several key parameters of local areas, which can be directly derived from local WAMS. The proposed method only uses WAMS data, hence it is independent from the offline data, such as network topology, device model and system parameters. Another outstanding feature of the proposed method is that only a few key parameters are required to be transferred from the local control centres to the global control centre. These features are helpful for the interconnected grid with different owners since exhaustive data are unnecessary for the global control centre. Case studies on the 10-generator New England system and one of 2007 operation cases of North China Power Grid validate its correctness and effectiveness.

Ligand-guided selection of aptamers against T-cell Receptor-cluster of differentiation 3 (TCR-CD3) expressed on Jurkat.E6 cells

We recently introduced a screening technology termed ligand-guided selection, (LIGS), to selectively identify target-specific aptamers from an evolved cell-SELEX library. Cell-SELEX utilizes a large combinatorial single-stranded oligonucleotide library and progressively selects DNA ligands against whole cells with variable DNA-binding affinities and specificities by repeated rounds of partition and amplification. LIGS exploits the partition step and introduces a secondary, pre-existing high-affinity monoclonal antibody (mAb) ligand to outcompete and elute specific aptamers towards the binding target of the antibody, not the cell. Here, using anti-CD3ε mAb against the cluster of differentiation 3 (CD3ε), as the guiding ligand against one of the domains of the T-cell Receptor (TCR) complex expressed on Jurkat.E6 cells, we discovered three specific aptamers against TCR complex expressed on an immortalized line of human T lymphocyte cells. In sum, we demonstrate that specific aptamers can be identified utilizing an antibody against a single domain of a multidomain protein complex in their endogenous state with neither post- nor pre-SELEX protein manipulation.

Ligand-Guided Selection of Target-Specific Aptamers: A Screening Technology for Identifying Specific Aptamers Against Cell-Surface Proteins.

We report on a new strategy for identifying highly specific aptamers against a predetermined epitope of a target. Termed "ligand-guided selection" (LIGS), this method uniquely exploits the selection step, the core of SELEX (Systematic Evolution Exponential enrichment). LIGS uses a naturally occurring stronger and highly specific bivalent binder, an antibody (Ab) interacting with its cognate antigen to outcompete specific aptamers from a partially enriched SELEX pool, as a strategy. We demonstrate the hypothesis of LIGS by utilizing an Ab binding to membrane-bound Immunoglobulin M (mIgM) to selectively elute aptamers that are specific for mIgM from a SELEX pool that is partially enriched toward mIgM expressing Ramos cells. The selected aptamers show specificity toward Ramos cells. We identified three aptamer candidates utilizing LIGS that could be outcompeted by mIgM Ab, demonstrating that LIGS can be successfully applied to select aptamers from a partially evolved cell-SELEX library, against predetermined receptor proteins using a cognate ligand. This proof-of-concept study introduces a new biochemical-screening platform that exploits the binding of a secondary stronger molecular entity to its target as a partition step, to identify highly specific artificial nucleic acid ligands.

Discrete optimization methods to fit piecewise affine models to data points

Fitting piecewise affine models to data points is a pervasive task in many scientific disciplines. In this work, we address the k-Piecewise Affine Model Fitting with Piecewise Linear Separability problem (k-PAMF-PLS) where, given a set of m points {a1,…,am}⊂Rn and the corresponding observations {b1,…,bm}⊂R, we have to partition the domain Rn into k piecewise linearly (or affinely) separable subdomains and to determine an affine submodel (i.e., an affine function) for each of them so as to minimize the total linear fitting error w.r.t. the observations bi.To solve k-PAMF-PLS to optimality, we propose a Mixed-Integer Linear Programming (MILP) formulation where symmetries are broken by separating shifted column inequalities. For medium-to-large scale instances, we develop a four-step heuristic involving, at each iteration, a point reassignment step based on the identification of critical points and a domain partition step based on multicategory linear classification. Differently from traditional approaches proposed in the literature for similar fitting problems, in both our exact and heuristic methods the domain partitioning and submodel fitting aspects are taken into account simultaneously.Computational experiments on real-world and structured randomly generated instances show that, with our MILP formulation with symmetry breaking constraints, we can solve to proven optimality many small-size instances. Our four-step heuristic turns out to provide close-to-optimal solutions for the small-size instances, while allowing to tackle instances of much larger size. The experiments also show that the combined impact of the main features of our heuristic is quite substantial when compared to standard variants not including them.We conclude the paper with an application to the identification of dynamical piecewise affine systems, for which we obtain promising results of comparable quality with those achieved with state-of-the-art methods from the literature (hinging hyperplane models and sum-of-norms regularization) on benchmark data sets.

Use of Factorial Design in the Development of Multiresidue Method for Determination of Pesticide Residues in Wheat by Liquid Chromatography-Tandem Mass Spectrometry

The evaluation of analytical methods for determining the level of residues and contaminants in food samples is a continuing need. To improve this evaluation, it is necessary to investigate different extraction procedures and conditions. A 23 factorial design was applied to establish an analytical method for determining pesticide residues in wheat by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Factors that influence the recovery of compounds, such as agitation and different processes of partition and cleanup, were investigated. Extracts were analyzed by LC-MS/MS with electrospray ionization in a triple quadrupole system. The use of ultrasonic agitation in the extraction step, deep freezing for the partition step, and C18 cleanup provided significantly better recoveries for most of the compounds evaluated. Assessment of each factor as well as interactions between factors allowed for a more effective evaluation of the parameters involved in the development of analytical methods. The validation results were satisfactory, since the method presented linearity (r 2) >0.99 for all compounds, the matrix effect ranged from 3 to 97 % and was corrected by matrix-matched standards, and recoveries ranged from 70 to 120 % with RSD ≤20 % for the spike levels of 10 and 100 μg kg−1. The method limit of detection and limit of quantification ranged from 3.3 to 6.7 μg kg−1 and from 10 to 20 μg kg−1, respectively, and the expanded uncertainty ranged from 15 to 32 %. The proposed method met the criteria for determination of 42 pesticides in wheat samples and was successfully tested in real samples.

Utilizing Circuit Structure for Scan Chain Diagnosis

Scan chain diagnosis has become a critical issue to yield loss in modern technology. In this paper, we present a scan chain partitioning algorithm and a scan chain reordering algorithm to improve scan chain fault diagnosis resolution. In our scan chain partition algorithm, we take into consideration not only logic dependency but also the controllability between scan flip-flops. After the partition step, the ordering of scan cells is performed to decrease the range of suspect faulty scan cells by a bipartite matching reordering algorithm. The experimental results show that our method can reduce the number of suspect scan cells from 378-31 to at most 3 for most cases of ITC'99 benchmarks.

Error Analysis and Comparison of Two Algorithms Measuring Compensated Income

We analyze and compare the errors of two numerical approaches for measuring compensated income. We prove that Vartia's algorithm and Breslaw and Smith's algorithm both converge quadratically; when the price change within each partition step is small, the error of Vartia's algorithm is approximately half that of Breslaw and Smith's algorithm. A theorem and the appropriate simulations with three different demand systems correct the existing error analysis of the two algorithms, and demonstrate that Vartia's algorithm is more accurate than Breslaw and Smith's.

An iterative network partition algorithm for accurate identification of dense network modules

A key step in network analysis is to partition a complex network into dense modules. Currently, modularity is one of the most popular benefit functions used to partition network modules. However, recent studies suggested that it has an inherent limitation in detecting dense network modules. In this study, we observed that despite the limitation, modularity has the advantage of preserving the primary network structure of the undetected modules. Thus, we have developed a simple iterative Network Partition (iNP) algorithm to partition a network. The iNP algorithm provides a general framework in which any modularity-based algorithm can be implemented in the network partition step. Here, we tested iNP with three modularity-based algorithms: multi-step greedy (MSG), spectral clustering and Qcut. Compared with the original three methods, iNP achieved a significant improvement in the quality of network partition in a benchmark study with simulated networks, identified more modules with significantly better enrichment of functionally related genes in both yeast protein complex network and breast cancer gene co-expression network, and discovered more cancer-specific modules in the cancer gene co-expression network. As such, iNP should have a broad application as a general method to assist in the analysis of biological networks.

Detection of pesticides in crops: A modified QuEChERS approach

The general term “pesticide” includes a large number of substances that belong to many different chemical classes. Pesticides are applied to crops at various stages of cultivation to provide protection against weeds and pests, and during post-harvest storage to preserve quality. The list of which pesticides are authorized for use in Europe is available on EU pesticides Database. The QuEChERS approach is a method designed for the analysis of pesticides in fruits and vegetables. This method is based on an extraction and clean-up step; it has been designed to be Quick Easy Cheap Effective Rugged and Safe. The aim of this study was to modify the QuEChERS method to be applied in the analysis of 9 organophosphate and 1 pyrethroid pesticides in raw materials for animal feeding introducing an additional liquid–liquid partition step. This additional step allowed us to concentrate the samples, avoiding any solvent evaporation, prior to the instrumental analysis. Once the method was optimized, it was carried out a pesticides quantization study using a GC–MS SIM multi-residue analysis. 45 samples of maize and soy coming from Northern Italy (Piedmont Region) were analysed during ten months. In 30 samples organophosphate pesticides were found up to 12.4 mg kg−1 of Chlorpyrifos, while no Deltamethrin was detected.

Nucleotide Bias Observed with a Short SELEX RNA Aptamer Library

Systematic evolution of ligands by exponential enrichment (SELEX) is a powerful in vitro selection process used for over 2 decades to identify oligonucleotide sequences (aptamers) with desired properties (usually high affinity for a protein target) from randomized nucleic acid libraries. In the case of RNA aptamers, several highly complex RNA libraries have been described with RNA sequences ranging from 71 to 81 nucleotides (nt) in length. In this study, we used high-throughput sequencing combined with bioinformatics analysis to thoroughly examine the nucleotide composition of the sequence pools derived from several selections that employed an RNA library (Sel2N20) with an abbreviated variable region. The Sel2N20 yields RNAs 51 nt in length, which unlike longer RNAs, are more amenable to large-scale chemical synthesis for therapeutic development. Our analysis revealed a consistent and early bias against inclusion of adenine, resulting in aptamers with lower predicted minimum free energies (ΔG) (higher structural stability). This bias was also observed in control, "nontargeted" selections in which the partition step (against the target) was omitted, suggesting that the bias occurred in 1 or more of the amplification and propagation steps of the SELEX process.

Template-directed ligation of tethered mononucleotides by t4 DNA ligase for kinase ribozyme selection.

Background In vitro selection of kinase ribozymes for small molecule metabolites, such as free nucleosides, will require partition systems that discriminate active from inactive RNA species. While nucleic acid catalysis of phosphoryl transfer is well established for phosphorylation of 5′ or 2′ OH of oligonucleotide substrates, phosphorylation of diffusible small molecules has not been demonstrated.Methodology/Principal FindingsThis study demonstrates the ability of T4 DNA ligase to capture RNA strands in which a tethered monodeoxynucleoside has acquired a 5′ phosphate. The ligation reaction therefore mimics the partition step of a selection for nucleoside kinase (deoxy)ribozymes. Ligation with tethered substrates was considerably slower than with nicked, fully duplex DNA, even though the deoxynucleotides at the ligation junction were Watson-Crick base paired in the tethered substrate. Ligation increased markedly when the bridging template strand contained unpaired spacer nucleotides across from the flexible tether, according to the trends: A2>A1>A3>A4>A0>A6>A8>A10 and T2>T3>T4>T6≈T1>T8>T10. Bridging T's generally gave higher yield of ligated product than bridging A's. ATP concentrations above 33 µM accumulated adenylated intermediate and decreased yields of the gap-sealed product, likely due to re-adenylation of dissociated enzyme. Under optimized conditions, T4 DNA ligase efficiently (>90%) joined a correctly paired, or T∶G wobble-paired, substrate on the 3′ side of the ligation junction while discriminating approximately 100-fold against most mispaired substrates. Tethered dC and dG gave the highest ligation rates and yields, followed by tethered deoxyinosine (dI) and dT, with the slowest reactions for tethered dA. The same kinetic trends were observed in ligase-mediated capture in complex reaction mixtures with multiple substrates. The “universal” analog 5-nitroindole (dNI) did not support ligation when used as the tethered nucleotide.Conclusions/SignificanceOur results reveal a novel activity for T4 DNA ligase (template-directed ligation of a tethered mononucleotide) and establish this partition scheme as being suitable for the selection of ribozymes that phosphorylate mononucleoside substrates.

A novel approach for fast codebook re-quantization

In this paper, we present a fast codebook re-quantization algorithm (FCRA) using codewords of a codebook being re-quantized as the training vectors to generate the re-quantized codebook. Our method is different from the available approach, which uses the original training set to generate a re-quantized codebook. Compared to the traditional approach, our method can reduce the computing time dramatically, since the number of codewords of a codebook being re-quantized is usually much smaller than the number of original training vectors. Our method first classifies codewords of a re-quantized codebook into static and active groups. This approach uses the information of codeword displacements between successive partitions to reject impossible candidates in the partition process of codebook re-quantization. By implementing a fast search algorithm used for vector quantization encoding (MFAUPI) in the partition step of FCRA, the computational complexity of codebook re-quantization can be further reduced significantly. Using MFAUPI, the computing time of FCRA can be reduced by a factor of 1.55–3.78. Compared with the available approach OARC (optimization algorithm for re-quantization codebook), our proposed method can reduce the codebook re-quantization time by a factor of about 8005 using a training set of six real images. This reduction factor is increased when the re-quantized codebook size and/or training set size are increased. It is noted that our proposed algorithm can generate the same re-quantized codebook as that produced by the OARC.