Nanoscale E-cadherin ligand patterns show threshold size for cellular adhesion and adherence junction formation

The role of ligand spatial distribution on the formation of cadherin mediated cell-cell contacts is studied utilizing nanopatterns of E-cadherin ligands. Protein patches ranging in size from 100 to 800 nm prepared by colloidal lithography critically influence adhesion, spreading, and formation of adherence junctions in epithelial cells. Cells at 100 nm patterns show poor adhesion, while larger pattern sizes show good adhesion, significant spreading, and defined cortical actin. We estimate a threshold of 0.03 μm(2) for epithelial cellular attachment via E-Cadherin.     

Large-scale dendrimer-based uneven nanopatterns for the study of local arginine-glycine-aspartic acid （RGD） density effects on cell adhesion

Cell adhesion processes are governed by the nanoscale arrangement of the extracellular matrix （ECM）, being more affected by local rather than global concentrations of cell adhesive ligands. In many cell-based studies, grafting of dendrimers on surfaces has shown the benefits of the local increase in concentration provided by the dendritic configuration, although the lack of any reported surface characterization has limited any direct correlation between dendrimer disposition and cell response. In order to establish a proper correlation, some control over dendrimer surface deposition is desirable. Here, dendrimer nanopatterning has been employed to address arginine-glycine-aspartic acid （RGD） density effects on cell adhesion. Nanopatterned surfaces were fully characterized by atomic force microscopy （AFM）, scanning tunneling microscopy （STM） and X-ray photoelectron spectroscopy （XPS）, showing that tunable distributions of cell adhesive ligands on the surface are obtained as a function of the initial dendrimer bulk concentration. Cell experiments showed a clear correlation with dendrimer surface layout： Substrates presenting regions of high local ligand density resulted in a higher percentage of adhered cells and a higher degree of maturation of focal adhesions （FAs）. Therefore, dendrimer nano- patterning is presented as a suitable and controlled approach to address the effect of local ligand density on cell response. Moreover, due to the easy modification of dendrimer peripheral groups, dendrimer nanopatterning can be further extended to other ECM ligands having density effects on cells.     

Digital switching of local arginine density in a genetically encoded self-assembled polypeptide nanoparticle controls cellular uptake

Cell-penetrating peptides (CPPs) are a class of molecules that enable efficient internalization of a wide variety of cargo in diverse cell types, making them desirable for delivery of anticancer drugs to solid tumors. For CPPs to be useful, it is important to be able to turn their function on in response to an external trigger that can be spatially localized in vivo. Here we describe an approach to turning on CPP function by modulation of the local density of arginine (Arg) residues by temperature-triggered micelle assembly of diblock copolymer elastin-like polypeptides (ELP(BC)s). A greater than 8-fold increase in cellular uptake occurs when Arg residues are presented on the corona of ELP(BC) micelles, as compared to the same ELP(BC) at a temperature in which it is a soluble unimer. This approach is the first to demonstrate digital 'off-on' control of CPP activity by an extrinsic thermal trigger in a clinically relevant temperature range by modulation of the interfacial density of Arg residues on the exterior of a nanoparticle.     

Dual reciprocity BEM: local versus global approximation functions for diffusion, convection and other problems

The use of the global approximation functions (elements of Pascal's triangle, sine expansions and others) in the dual reciprocity boundary element method is compared to the better known local radial basis functions for convection, diffusion and other problems in which the volume integrals considered contain first and second derivatives of the problem variables, time derivatives and sums and products of functions, including nonlinear terms. It will be shown that whilst it is possible to obtain accurate solutions to the problems considered using the global functions, a successful solution to a given problem depends very much on the function chosen, as well as other factors.     

Impact of a quasi-stochastic cellular automaton backscatter scheme on the systematic error and seasonal prediction skill of a global climate model

The impact of a nonlinear dynamic cellular automaton (CA) model, as a representation of the partially stochastic aspects of unresolved scales in global climate models, is studied in the European Centre for Medium Range Weather Forecasts coupled ocean-atmosphere model. Two separate aspects are discussed: impact on the systematic error of the model, and impact on the skill of seasonal forecasts. Significant reductions of systematic error are found both in the tropics and in the extratropics. Such reductions can be understood in terms of the inherently nonlinear nature of climate, in particular how energy injected by the CA at the near-grid scale can backscatter nonlinearly to larger scales. In addition, significant improvements in the probabilistic skill of seasonal forecasts are found in terms of a number of different variables such as temperature, precipitation and sea-level pressure. Such increases in skill can be understood both in terms of the reduction of systematic error as mentioned above, and in terms of the impact on ensemble spread of the CA's representation of inherent model uncertainty.     

Study of cellular adhesion with scanning acoustic microscopy

A mechanical scanning acoustic reflection microscope was applied to living cells (e.g., osteoblasts) to observe their undisguised shapes and to evaluate their adhesive conditions at a substrate interface. A conditioned medium was collected from a bone-metastatic breast cancer cell line, MDA-MB-231, and cultured with an immature osteoblast cell line, MC3T3-E1. To characterize the cellular adhesion, MC3T3-E1 osteoblasts were cultured with or without MDA-MB-231 conditioned medium for 2 days, then assayed with the scanning acoustic reflection microscope. At 600 MHz the scanning acoustic reflection microscope clearly indicated that MC3T3-E1 cells cultured with MDA-MB-231 conditioned medium had both an abnormal shape and poor adhesion at the substrate interface. The results are compared with those obtained with laser scanning confocal microscopy and are supported by a simple multilayer model.     

Derivative-free global ship design optimization using global/local hybridization of the DIRECT algorithm

The application of global/local hybrid DIRECT algorithms to the simulation-based hull form optimization of a military vessel is presented, aimed at the reduction of the resistance in calm water. The specific features of the black-box-type objective function make the problem suitable for the application of DIRECT-type algorithms. The objective function is given by numerical iterative procedures, which could lead to inaccurate derivative calculations. In addition, the presence of local minima cannot be excluded a priori. The algorithms proposed (namely DIRMIN and DIRMIN-2) are hybridizations of the classic DIRECT algorithm, with deterministic derivative-free local searches. The algorithms’ performances are first assessed on a set of test problems, and then applied to the ship optimization application. The numerical results show that the local hybridization of the DIRECT algorithm has beneficial effects on the overall computational cost and on the efficiency of the simulation-based optimization procedure.     

Image segmentation model based on adaptive adjustment of global and local information

In this article, an adaptive mixture model for image segmentation that synthesizes both global information and local information using a new adaptive balance function has been proposed. Given the variety of possible image characteristics that may have to be processed, the proposed model can adaptively adjust the weighting to drive curve evolution trends and states. In this way, the intensity information of weak boundaries and complex backgrounds can be extracted more precisely, thus enabling the model to produce better results for low‐contrast images and complex structures. In addition, a Gaussian filtering process has been added to the model to smooth and standardize the level set function, and a parameter has been introduced to speed up the curve evolution. A penalty term is also used to eliminate the need for complex re‐initialization procedures. Experimental results for various kinds of images efficiently demonstrate the good performance of the proposed model in terms of both speed and accuracy. © 2016 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 26, 179–187, 2016     

On close relations of local likelihood density estimation

Summary Recent papers of Copas (1995), Hjort and Jones (1996) and Loader (1996) have developed closely related methods for “local likelihood” density estimation. In various places, however, a more “simple-minded” and explicit analogue of local polynomial fitting in regression has been proposed for density estimation. By introducing the usual kind of binning procedure into Hjor and Jones' method, it is shown how the more and less sophisticated versions can be reconciled. Also, we attempt to understand better the role of the attractive subclass of local likelihood methodology proposed by Loader. Finally, we look at a further subset of methods and make some theoretical comparisons between members of this class.     

The effects of nanoscale pits on primary human osteoblast adhesion formation and cellular spreading

Current understanding of the mechanisms involved in ossesoinegration following implantation of a biomaterial has led to an emphasis being placed on the modification of material topography to control interface reactions. Recent studies have inferred nanoscale topography as an important mediator of cell adhesion and differentiation. Biomimetic strategies in orthopaedic research aim to exploit these influences to regulate cellular adhesion and subsequent bony tissue formation. Here experimental topographies of nanoscale pits demonstrating varying order have been fabricated by electron-beam lithography in (poly)carbonate. Osteoblast adhesion to these nanotopographies was ascertained by quantification of the relation between adhesion complex formation and total cell area. This study is specifically concerned with the effects these nanotopographies have on adhesion formation in S-phase osteoblasts as identified by BrdU incorporation. Nanopits were found to reduce cellular spreading and adhesion formation.     

Comparing implementations of global and local indicators of spatial association

Functions to calculate measures of spatial association, especially measures of spatial autocorrelation, have been made available in many software applications. Measures may be global, applying to the whole data set under consideration, or local, applying to each observation in the data set. Methods of statistical inference may also be provided, but these will, like the measures themselves, depend on the support of the observations, chosen assumptions, and the way in which spatial association is represented; spatial weights are often used as a representational technique. In addition, assumptions may be made about the underlying mean model, and about error distributions. Different software implementations may choose to expose these choices to the analyst, but the sets of choices available may vary between these implementations, as may default settings. This comparison will consider the implementations of global Moran’s I, Getis–Ord G and Geary’s C, local \(I_i\) and \(G_i\), available in a range of software including Crimestat, GeoDa, ArcGIS, PySAL and R contributed packages.     

有机铁改性玄武岩纤维及其对微生物的附着行为

以草酸和FeSO₄7H₂O为原料,利用液相沉积法对玄武岩纤维（BF）进行表面改性,以SEM、EDS、XPS、接触角分析仪和Zeta电位测试仪研究BF改性前后的微观形貌、元素组成、表面亲水性和电负性等性能。以枯草芽孢杆菌在不同的生长环境中的生长曲线来判断BF改性前后的生理毒性,以纯菌吸附实验和活性污泥固定实验考察有机铁改性玄武岩纤维（MBF）对微生物附着行为的影响。结果表明:MBF的亲水性和电负性得到明显改善,MBF的水接触角由89.71°降至为56.74°,表面Zeta电位由-18.53 mV提升至-5.03 mV; MBF对细菌的生长无抑制作用,不存在生理毒性;在12 h后MBF表面固定的微生物量可达27.91 gm-2,表明有机铁改性BF有助于促使更多的生物量附着在载体表面,进而有利于提高载体的污/废水处理效果。      

Influence of non degenerated joint on the global and local behavior of joined plates

We consider a three-dimensional transport problem (thermoconductivity, diffusion, etc.) in joined thin plates under condition that the characteristic dimension of the joint is comparable with the thickness of the plates and that the joint is made of a material with transport properties similar to the transport properties of materials of the plates (such joint is referred to as a non-degenerated joint). We expand the technique of local perturbation, developed earlier in Gaudiello and Kolpakov (2011) for beams, to plates with non-degenerated joints. Since joints between plates have more complex structure than joints between beams, the modification of the method for plates is a non-trivial task.     

Influence of non degenerated joint on the global and local behavior of joined rods

We consider transport (thermoconductivity, diffusion, etc.) problem in a system of joined n-dimensional (n = 2, 3) thin rods, We assume that the joint has the size compared with the characteristic diameter of the rods and the joint is made of materials with transport properties similar to the transport properties of materials of the rods (such joint is referred as non degenerated joint). Using a technique of local perturbation, we construct asymptotic representations of the solution and obtain the limit model for some types of rods and joints. In all the cases, we find that the non degenerated joint is ignored on the global level (e.g., in framework models) and it manifests itself on the local level (in particular, it determines the gradient of the solution in and near the joint).     

Design of truss-like cellular structures using relative density mapping method

Truss-like cellular structures have great potential to be applied in light-weight design applications. However, determining the appropriate designs for these truss-like cellular structures can be a challenging task due to their geometric complexities and prohibitive computational costs in the design process. In this research, a new design method is proposed which can drastically reduce computational costs and design parameters, while maintaining the performance of the targeted outcome. Furthermore, the proposed method facilitates cellular structure designs that can handle multiple loading conditions. The proposed method utilizes the relative density information obtained from a solid topology optimization to automatically determine the diameter of each individual strut in the structure, which collectively represent the set of design variables. This allows the method to produce lattice structures that can perform reliably under multiple loading conditions and also reduce the computational cost associated with the design of these structures. The efficacy of the developed method is compared to existing methods including the size matching and scaling method that combines solid-body analysis and a predefined unit–cell library.