Change of short-term memory effect in acute ischemic ventricular myocardium: A computational study

The ionic mechanism of change in short-term memory (STM) during acute myocardial ischemia has not been well understood. In this paper, an advanced guinea pig ventricular model developed by Luo and Rudy was used to investigate STM property of ischemic ventricular myocardium. STM response was calculated by testing the time to reach steady-state action potential duration (APD) after an abrupt shortening of basic cycling length (BCL) in the pacing protocol. Electrical restitution curves (RCs), which can simultaneously visualize multiple aspects of APD restitution and STM, were obtained from dynamic and local S1S2 restitution portrait (RP), which consist of a longer interval stimulus (S1) and a shorter interval stimulus (S2). The angle between dynamic RC and local S1S2 RC reflects the amount of STM. Our results indicated that compared with control (normal) condition, time constant of STM response in the ischemic condition decreased significantly. Meanwhile the angle which reflects STM amount is less in ischemic model than that in control model. By tracking the effect of ischemia on intracellular ion concentration and membrane currents, we declared that changes in membrane currents caused by ischemia exert subtle influences on STM; it is only the decline of intracellular calcium concentration that give rise to the most decrement of STM.     

Spectral and complexity analysis of scalp EEG characteristics for mild cognitive impairment and early Alzheimer's disease

Amnestic mild cognitive impairment (aMCI) often is an early stage of Alzheimer's disease (AD). MCI is characterized by cognitive decline departing from normal cognitive aging but that does not significantly interfere with daily activities. This study explores the potential of scalp EEG for early detection of alterations from cognitively normal status of older adults signifying MCI and AD. Resting 32-channel EEG records from 48 age-matched participants (mean age 75.7 years)—15 normal controls (NC), 16 early MCI, and 17 early stage AD—are examined. Regional spectral and complexity features are computed and used in a support vector machine model to discriminate between groups. Analyses based on three-way classifications demonstrate overall discrimination accuracies of 83.3%, 85.4%, and 79.2% for resting eyes open, counting eyes closed, and resting eyes closed protocols, respectively. These results demonstrate the great promise for scalp EEG spectral and complexity features as noninvasive biomarkers for detection of MCI and early AD.     

An effective dissimilarity measure for clustering of high-dimensional categorical data

Clustering is to group similar data and find out hidden information about the characteristics of dataset for the further analysis. The concept of dissimilarity of objects is a decisive factor for good quality of results in clustering. When attributes of data are not just numerical but categorical and high dimensional, it is not simple to discriminate the dissimilarity of objects which have synonymous values or unimportant attributes. We suggest a method to quantify the level of difference between categorical values and to weigh the implicit influence of each attribute on constructing a particular cluster. Our method exploits distributional information of data correlated with each categorical value so that intrinsic relationship of values can be discovered. In addition, it measures significance of each attribute in constructing respective cluster dynamically. Experiments on real datasets show the propriety and effectiveness of the method, which improves the results considerably even with simple clustering algorithms. Our approach does not couple with a clustering algorithm tightly and can also be applied to various algorithms flexibly.     

Experimental and theoretical study on H2/CO2 separation by a five-step one-column psa process

An experimental and theoretical study is performed for bulk separation of H₂/CO₂ mixture (70/30 volume %) by PSA process with zeolite 5A, a process widely used commercially in conjunction with the catalytic steam reforming of natural gas or naphtha. For the optimized adsorption conditions of PSA, the characteristics of adsorption/desorption characteristics have been studied through breakthrough and desorption experiments under various conditions. The purge-to-feed ratio is important to the H₂ product purity only at a long adsorption step time. H₂ could be concentrated from 70% in the feed to 99.99% at H₂ recovery of 67.5%. The results of all five steps in PSA are successfully predicted by the LDF model considering an energy balance and nonlinear isotherm. For the model, the effective diffusivities (D,) are obtained separately from the uptake curves of H₂ and CO₂. The Langmuir-Freundlich isotherm is used to correlate the experimental equilibrium data and is very well fitted to the results.     

Tactile display with tangential and normal skin displacement for robot-assisted surgery

This paper proposes a tactile display providing both shear and normal feedback to the fingertip for generating three-axis tactile feedback during teleoperation of a surgical robot. The display is composed of five balloons actuated by controlling the pneumatic pressure. The implemented display is 18?mm?×?18?mm?×?15?mm. This size is suitable for mounting the display onto the master controls of a surgical robot. The maximum normal and shear displacements are 2 and 1.3?mm, respectively. The proposed tactile display may provide perceivable stimuli to a human finger pad in all five directions: normal, distal, proximal, radial, and ulnar. This paper also reports on the results of psychophysical measurement of the minimum perceivable movement of the developed tactile display for each of the five directions.     

Underactuated miniature bending joint composed of serial pulleyless rolling joints

This paper proposes a miniature bending joint composed of serial rolling joints; it refers to the classification of small joints of other products and studies on surgical applications according to the structures and transmissions. To achieve this, a pulleyless rolling joint is introduced as a unit component and the basic design principle is established for the joint. A simple mechanism guarantees a smooth rolling contact using elastic fixtures. Underactuation, which prevents S-shaped curvature similar to buckling, is applied to drive the bending joint with a limited number of wire cables. Using a 1-DOF real-sized prototype, experiments were performed to measure the motion accuracy and payload capacity from various angles to evaluate the efficacy of an improved design that enhances the payload on the distal end. This novel joint is applicable to a wider variety of surgical tools and catheters relative to other candidates owing to its small constant curvature, reasonable payload capacity, and miniature size.     

Microstructural Evolution of Gas-Pressure-Sintered Si3N4 with Yb2O3 as a Sintering Aid

Microstructural evolution of gas-pressure-sintered Si₃N₄ with Yb₂O₃ as a sintering aid was observed. Microstructures typical for in situ toughened Si₃N₄, i.e., large elongated grains randomly distributed in a fine matrix, were observed. However, the size of the elongated grains near the surface was much larger than that at the center, resulting in two distinct regions: an inner region and an outer region. The smaller the amount of Yb₂O₃ added, the larger the difference in the size of the elongated grains between the outer and inner regions. The difference between microstructures was diminished when 16 wt% Yb₂O₃ was added. The microstructural change with Yb₂O₃ content was attributed to the evaporation of Yb-containing liquid phase from the surface.     

An apparent kinetic model for the carbonation of calcium oxide by carbon dioxide

For the apparent kinetics of the carbonation reaction of calcium oxide by carbon dioxide, as a kind of noncatalytic gas–solid reaction, a model equation has been proposed as follows: X=kbt/(b+t), where X is the conversion of CaO; k, a kinetic rate constant (time⁻¹); b, a constant (time) equivalent to the time taken to attain half the ultimate conversion of CaO, and t, the time. As a result of analyses for some literature-reported data of CaO-carbonation conversion, it has been found that the rate of the carbonation can be well represented by dX/dt=k(1−X/X_u)², where X_u is the ultimate conversion of CaO, which is given by the product of two parametric constants, k and b. The constants k and b in the two rate control regimes of CaO-carbonation, chemical reaction control and diffusion control, have been determined as functions of temperature, respectively. The activation energy in the carbonation of surface CaO with CO₂ is estimated to about 72 kJ/mol regardless of the sources of CaO, however, that in the diffusion control regime appears differently as 102.5 (mesoporous CaO) or 189.3 kJ/mol (commercial-available CaO), possibly due to the morphological differences of the two CaO samples. From a practical point of view, the simple model equation proposed in this study deserves attention in that the CaO-carbonation behavior at working temperatures higher than 700 °C could be closely predicted.     

A resource-aware scheduling algorithm with reduced task duplication on heterogeneous computing systems

To satisfy the high-performance requirements of application executions, many kinds of task scheduling algorithms have been proposed. Among them, duplication-based scheduling algorithms achieve higher performance compared to others. However, because of their greedy feature, they duplicate parents of each task as long as the finish time can be reduced, which leads to a superfluous consumption of resource. However, a large amount of duplications are unnecessary because slight delay of some uncritical tasks does not affect the overall makespan. Moreover, these redundant duplications would occupy the resources, delay the execution of subsequent tasks, and increase the schedule makespan consequently. In this paper, we propose a novel duplication-based algorithm designed to overcome the above drawbacks. The proposed algorithm is to schedule tasks with the least redundant duplications. An optimizing scheme is introduced to search and remove redundancy for a schedule generated by the proposed algorithm further. Randomly generated directed acyclic graphs and two real-world applications are tested in our experiments. Experimental results show that the proposed algorithm can save up to 15.59  % resource consumption compared with the other algorithms. The makespan has improvement as well.     

A study on security strategy in ICT convergence environment

In the knowledge and information society, the value of utilizing ICT technology in companies is being newly interpreted upon the convergence of business and information technology of companies. Accordingly, companies are ensuring corporate competitiveness by improving product productivity and reducing the consumption of human/physical resources through the change of strategic management environment using ICT technology. On the other hand, companies’ core information is being leaked outside of company from the convergence with ICT technology and its scale is increasing each year. Accordingly, the need for improving the level of security according to companies’ informatization level is increasing. However, studies are lacking on the composition of security strategy in suitable forms according to the scale of company and level of retaining resources. Accordingly, this study examined the security advancement steps to verify the present condition of companies’ security and design security strategy from a macroscopic perspective by improving the level of security according to the scale of company and present condition of resources.