Acquisition of high-precision images for non-contact atomic force microscopy

The atomic force microscope (AFM) system has evolved into a useful tool for direct measurements of intermolecular forces with atomic-resolution characterization that can be employed in a broad spectrum of applications. The distance between cantilever tip and sample surface in non-contact AFM is a time-varying parameter even for a fixed sample height, and typically difficult to identify. A remedy to this problem is to directly identify the sample height in order to generate high-precision atomic-resolution images. For this, the microcantilever (which forms the basis for the operation of AFM) is modeled as a single mode approximation and the interaction between the sample and cantilever is derived from a van der Waals potential. Since in most practical applications only the microcantilever deflection is accessible, we will use merely this measurement to identify the sample height. In most non-contact AFMs, cantilevers with high-quality factors are employed essentially for acquiring high-resolution images. However, due to high-quality factor, the settling time is relatively large and the required time to achieve a periodic motion is long. As a result, identification methods based on amplitude and phase measurements cannot be efficiently utilized. The proposed method overcomes this shortfall by using a small fraction of the transient motion for parameter identification, so the scanning speed can be increased significantly. Furthermore, for acquiring atomic-scale images of atomically flat samples, the need for feedback loop to achieve setpoint amplitude is basically eliminated. On the other hand, for acquiring atomic-scale images of highly uneven samples, a simple PI controller is designed to track the desired constant sample height. Simulation results are provided to demonstrate the feasibility of the approach for both sample height identification and tracking the desired sample height.     

Optimization of Water Distribution Networks Using Integer Linear Programming

In this study optimum design of municipal water distribution networks for a single loading condition is determined by the branch and bound integer linear programming technique. The hydraulic and optimization analyses are linked through an iterative procedure. This procedure enables us to design a water distribution system that satisfies all required constraints with a minimum total cost. The constraints include pipe sizes, which are limited to the commercially available sizes, reservoir levels, pipe flow velocities, and nodal pressures. Accuracy of the developed model has been assessed using a network with limited solution alternatives, the optimal solution of which can be determined without employing optimization techniques. The proposed model has also been applied to a network solved by others. Comparison of the results indicates that the accuracy and convergence of the proposed method is quite satisfactory.     

A Framework for Evaluating Distributed Object Models and its Application to Web Engineering

The success of building distributed object systems depends on important factors such as architecture, the distributed object model (DOM) selected, and the process adapted in the selection of the DOM. There are a number of DOMs. Although the primary goals of these models are the same, each model has a unique underlying architecture, maturity, and features provided. A critical evaluation of DOMs is thus needed by those organizations that are considering migrating to distributed object computing. The evaluation process can be time-consuming and may drain organizational resources. Most of the current evaluation processes adopted by organizations are not generic enough, and they concentrate only on the problem on hand. Hence, they cannot be used by any other organization, sometimes not even a different project at the same organization. Therefore, a more generalized framework or template is required to evaluate DOMs. This paper proposes a framework to evaluate DOMs. A number of important managerial items such as cost, personnel, and technology resources, training, enterprise changes, and time constraints have been identified, explained, and justified as the evaluation criteria. An evaluation of the most widely used DOMs, CORBA, DCOM, and RMI, is provided using the above criteria. Finally, a case study of a production web-based system is presented to demonstrate the use of the framework.     

Analysis of depth estimation error for cylindrical stereo imaging

Conventional stereo imaging uses area CCDs for which depth perception error has been analyzed in our past research (Comput. Vision Image understand. 63 (3) (1996) 447). In this work we analyze the depth perception error for a stereo system that uses two rotating linear CCD cameras to create cylindrical stereo images. Theoretical analysis shows certain advantages to cylindrical stereo imaging over conventional methods. Initial experimental results are presented to validate the theoretical results. Unlike normal area CCDs, cylindrical images captured by rotating linear CCD cameras can produce very high-resolution images thereby substantially reducing the error in 3D estimation.     

Direct sampling from muscle cross sections for electrophoretic analysis of individual mitochondria

Muscle is a highly heterogeneous tissue. Practical approaches to sample selectively small regions of muscle cross sections would help to effectively utilize analytical techniques on muscle studies while taking into account tissue heterogeneity. In this report, semimembranosus muscle tissue cross sections were directly sampled and analyzed by capillary electrophoresis (CE) with laser-induced fluorescence detection (LIF). Prior to CE-LIF analysis, a small region in the muscle cross section was stained with 10-nonyl acridine orange (NAO) which is a mitochondrion-selective fluorescent probe known to form a stable complex with cardiolipin, a phospholipid found only in mitochondria. By micromanipulation, the injection end of the capillary was brought into contact with the tissue exhibiting fluorescently labeled mitochondria. Sampling from a region similar in size to the cross section of a single fiber was carried out by applying 11 kPa of negative pressure for 3 s. When an electric field of -200V/cm was applied, fluorescently labeled mitochondria electromigrated and were individually detected by postcolumn LIF detection. For each sample, the electropherogram displays a migration time window with a collection of narrow peaks. The collection of individual peak measurements is represented as a distribution of individual intensities related to cardiolipin content of mitochondria and a distribution of individual electrophoretic mobilities. Positioning the capillary injection end was sufficiently spatially accurate to deplete mitochondria in the sampled region upon repetitive injections. Treatment of a muscle cross section with a protease (trypsin) prior to mitochondria sampling resulted in a higher number of detected mitochondria, suggesting that one of the effects of this enzyme is a partial digestion of the muscles myofibrils, which eases the release of interfibrillar mitochondria entangled within these fibers. The protease treatment also resulted in changes to the electrophoretic mobility distribution of individual mitochondria, which may imply that partial digestion of proteins bound to the mitochondria contributes to the alteration in the electrophoretic mobility of mitochondria. The ability to sample a region as small as a single muscle fiber cross section and its direct CE-LIF analysis opens exciting possibilities for the direct analysis of muscle biopsies and mapping the mitochondrial electrophoretic properties in highly heterogeneous tissues.     

A hybrid multi-objective shuffled frog-leaping algorithm for a mixed-model assembly line sequencing problem

In this paper, a mixed-model assembly line (MMAL) sequencing problem is studied. This type of production system is used to manufacture multiple products along a single assembly line while maintaining the least possible inventories. With the growth in customers’ demand diversification, mixed-model assembly lines have gained increasing importance in the field of management. Among the available criteria used to judge a sequence in MMAL, the following three are taken into account: the minimization of total utility work, total production rate variation, and total setup cost. Due to the complexity of the problem, it is very difficult to obtain optimum solution for this kind of problems by means of traditional approaches. Therefore, a hybrid multi-objective algorithm based on shuffled frog-leaping algorithm (SFLA) and bacteria optimization (BO) are deployed. The performance of the proposed hybrid algorithm is then compared with three well-known genetic algorithms, i.e. PS-NC GA, NSGA-II, and SPEA-II. The computational results show that the proposed hybrid algorithm outperforms the existing genetic algorithms, significantly in large-sized problems.     

On insecurity of Naor-Pinkas' distributed oblivious transfer

This paper analyses the security of Naor-Pinkas' distributed oblivious transfer [M. Naor, B. Pinkas, Distributed oblivious transfer, in: Advances in Cryptology—Proceedings of ASIACRYPT'00, Lecture Notes in Computer Science, vol. 1976, Springer-Verlag, 2000]. It is shown that the schemes presented in the paper do not protect the chooser/sender in the information theoretic sense.     

Robust group fused lasso for multisample copy number variation detection under uncertainty

One of the most important needs in the post‐genome era is providing the researchers with reliable and efficient computational tools to extract and analyse this huge amount of biological data, in which DNA copy number variation (CNV) is a vitally important one. Array‐based comparative genomic hybridisation (aCGH) is a common approach in order to detect CNVs. Most of methods for this purpose were proposed for one‐dimensional profiles. However, slightly this focus has moved from one‐ to multi‐dimensional signals. In addition, since contamination of these profiles with noise is always an issue, it is highly important to have a robust method for analysing multi‐sample aCGH profiles. In this study, the authors propose robust group fused lasso which utilises the robust group total variations. Instead of l _2,1 norm, the l ₁ − l ₂ M‐estimator is used which is more robust in dealing with non‐Gaussian noise and high corruption. More importantly, Correntropy (Welsch M‐estimator) is also applied for fitting error. Extensive experiments indicate that the proposed method outperforms the state‐of‐the art algorithms and techniques under a wide range of scenarios with diverse noises.Inspec keywords: genomics, DNA, molecular biophysics, Gaussian noise, entropyOther keywords: robust group fused lasso, multisample copy number variation detection, post‐genome era, computational tools, biological data, DNA copy number variation, array‐based comparative genomic hybridisation, one‐dimensional profiles, one‐dimensional signals, multidimensional signals, profile contamination, multisample aCGH profiles, robust group total variations, l₁ ‐l₂ M‐estimator, nonGaussian noise, correntropy, Welsch M‐estimator, fitting error, diverse noises     

Investigating the effect of nanoparticles on the rutting behaviour of hot-mix asphalt

Rutting is considered as one of the major damages in asphalt mixtures. In this study, different types of nanoparticles such as TiO₂, Al₂O₃, Fe₂O₃ and ZnO in different percentages were added to the base asphalt binder in order to decrease the rutting potential of hot-mix asphalt (HMA). In the first step, asphalt binder tests for characteristics such as penetration grade, ductility, softening point and viscosity were performed on the asphalt binder modified by the nanoparticles. Then, after preparing HMA samples, the static creep test was done at two stress levels at a specific temperature. Results of this study showed that using the nanoparticles improved the behavioural properties of the asphalt binder and decreased rutting in asphalt mix samples. Furthermore, scanning electron microscope images taken from the asphalt binder samples modified by the nanoparticles demonstrated that these nanoparticles were properly distributed in the asphalt binder space and had a positive effect on the rutting performance of the asphalt mixes.