Automated detection of pulmonary nodules in helical CT images based on an improved template-matching technique

The purpose of this study is to develop a technique for computer-aided diagnosis (CAD) systems to detect lung nodules in helical X-ray pulmonary computed tomography CT) images. We propose a novel template-matching technique based on a genetic algorithm (GA) template matching (GATM) for detecting nodules existing within the lung area; the GA was used to determine the target position in the observed image efficiently and to select an adequate template image from several reference patterns for quick template matching. In addition, a conventional template matching was employed to detect nodules existing on the lung wall area, lung wall template matching (LWTM), where semicircular models were used as reference patterns; the semicircular models were rotated according to the angle of the target point on the contour of the lung wall. After initial detecting candidates using the two template-matching methods, we extracted a total of 13 feature values and used them to eliminate false-positive findings. Twenty clinical cases involving a total of 557 sectional images were used in this study. 71 nodules out of 98 were correctly detected by our scheme (i.e., a detection rate of about 72%), with the number of false positives at approximately 1.1/sectional image. Our present results show that our scheme can be regarded as a technique for CAD systems to detect nodules in helical CT pulmonary images.     

2-Aminoethoxydiphenyl borate (2-APB) inhibits capacitative calcium entry independently of the function of inositol 1,4,5-trisphosphate receptors

Capacitative calcium entry (CCE), the mechanism that replenishes intracellular calcium stores after depletion, is essential to intracellular calcium signaling. CCE is mediated by the channels in the plasma membrane generally referred to as "store operated channels (SOCs)". However, the molecular identity of the SOCs has never been determined, and the mechanism of the activation of SOCs remains to be elucidated. Recent studies have demonstrated that 2-aminoethoxydiphenyl borate (2-APB), which has been found to be an antagonist of inositol 1,4,5-trisphosphate receptors (IP3Rs), inhibits CCE, suggesting that IP3Rs channel activity is essential to the generation of CCE. However, CCE has also been reported to occur normally in IP3R-deficient cells. In order to resolve this discrepancy, we investigated the effect of 2-APB on CCE in IP3Rs-deficient cells. In response to store depletion with thapsigargin or N,N,N',N'-tetrakis (2-pyridylmethyl) ethylene diamine (TPEN), CCE was generated in IP3Rs-deficient cells the same as in wild-type cells, however, 2-APB abolished CCE in IP3Rs-deficient cells, despite the fact that this cell line does not possess functional IP3Rs. We also examined the effect of 2-APB on several types of TRP Ca2+ channels, which exhibit properties similar to those of SOCs. 2-APB had a different inhibitory effect on spontaneous and thapsigargin-induced Ba2+ influx in cells that transiently expressed individual TRP subtypes. These results suggest that the channel activity of IP3Rs is not essential to the generation of CCE in this cell line and that 2-APB inhibits CCE independently of the function of IP3Rs.     

Motion Control of Passive Intelligent Walker Using Servo Brakes

We propose a new intelligent walker based on passive robotics that assists the elderly, handicapped people, and the blind who have difficulty in walking. We developed a prototype of the robot technology walker (RT walker), a passive intelligent walker that uses servo brakes. The RT walker consists of a support frame, two casters, two wheels equipped with servo brakes, and it has passive dynamics that change with respect to applied force/moment. This system is intrinsically safe for humans, as it cannot move unintentionally, i.e., it has no driving actuators. In addition, the RT walker provides a number of navigational features, including good maneuverability, by appropriately controlling the torque of servo brakes based on RT. We propose a human adaptive motion control algorithm that changes the apparent dynamics to adapt to user difficulties, and an environmentally adaptive motion control algorithm, which incorporates environmental information to provide obstacle/step avoidance and gravity compensation functions. The proposed control algorithms are experimentally applied to the RT walker to test their validity.     

Synthesis of the Bi-2222 Compounds of Bi–Sr–Ln(Zr)–Cu–O (Ln = Sm,Eu, Gd,and Dy)

Bi-based superconducting compounds with the 2222 structure has been already synthesized in the Bi₂Sr₂- (Ln_1−x Ce _x )₂Cu₂O_10+y (Ln = Sm, Eu, and Gd) systems. One of the characteristics of these compounds is the existence of the fluorite-like (Ln_1−x Ce _x )₂O₂ block between two CuO₅ pyramids in the crystal structure. The tetravalent ions of Ce⁴⁺ are reported to be necessary to stabilize the 2222 structure. Recently, we have discovered that the Bi-2222 phase could be composed in the Bi₂Sr₂(Ln_2−x Zr _x )Cu₂O _z (Ln = Sm, Eu, Gd, and Dy) systems, where Zr⁴⁺ is used as a new tetravalent ion stabilizing the 2222 structure in stead of Ce⁴⁺. In the new system, nearly single 2222 phase samples have been obtained at the nominal composition of x=0.5 (Ln = Sm, Eu, and Gd) and in the range of 0.1≤x≤0.3 (Ln = Dy). Among them, the sample with Ln = Gd has the smallest resistivity at 273 K. But it is a semiconductor, and the conduction process at low temperatures is assumed to be followed by a two-dimensional VRH. The experimental results for the Gd samples with a partial substitution of Pb for Bi in the Bi₂Sr₂(Gd_2−x Zr _x )Cu₂O _z system are also reported.     

EACLE : Energy-Aware Clustering Scheme with Transmission Power Control for Sensor Networks

In this paper, we propose a new energy efficient clustering scheme with transmission power control named “EACLE” (Energy-Aware CLustering scheme with transmission power control for sEnsor networks) for wireless sensor networks, which are composed of the following three components; “EACLE clustering” is a distributed clustering method by means of transmission power control, “EACLE routing” builds a tree rooted at a sink node and sets the paths from sensor nodes taking energy saving into consideration, and “EACLE transmission timing control” changes the transmission timing with different levels of transmission power to avoid packet collisions and facilitates packet binding. With an indoor wireless channel model which we obtained from channel measurement campaigns in rooms and corridors and an energy consumption model which we obtained from a measurement of a chipset, we performed computer simulations to investigate the performance of EACLE in a realistic environment. Our simulation results indicate that EACLE outperforms a conventional scheme such as EAD (Energy-Aware Data-centric routing) in terms of communication success rate and energy consumption. Furthermore, we fully discuss the impact of transmission power and timing control on the performance of EACLE.     

A parameter space approach to fixed-order robust controller synthesis by quantifier elimination

This paper proposes a new method of parameter space design for robust control synthesis which guarantees the real stability radius constraint, accomplished by using Quantifier Elimination (QE). We aim at practicality by employing the scheme to combine the Sign Definite Condition (SDC) and a special QE algorithm using the Sturm-Habicht sequence. The validity of our approach is confirmed by several design examples.     

Surface acoustic wave based sensors employing ionic liquid for hydrogen sulfide gas detection

This paper describes a new type hydrogen sulfide (H₂S) gas sensor using ionic liquid (IL). In this sensor, a reservoir for the IL was integrated on a surface acoustic wave (SAW) resonator. The IL serves as an absorber for H₂S gas. Mass change due to this absorption is detected as shift in the resonant frequency. In this study, we fabricated and demonstrated the sensor using the lithium niobate (LiNbO₃) SAW resonator with the resonant frequency of 38 MHz. The integrated reservoir was filled by the IL 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]-[PF₆]). As an experimental result, we observed the linear correlation between the frequency-shift and the exposure time of the sensor to the H₂S gas.     

Classification of amorphous-silicon microstructures by structural parameters: molecular dynamics study

Amorphous silicon is the most popular material in the field of semiconductors. However, little is known about its microstructures. To understand the dependence of these microstructures on the fabrication process and on structural relaxation, amorphous silicon samples fabricated by various simulated processes are classified according to structural parameters within the molecular dynamics method.

The results show that the amorphous structures fabricated by the melt-quench method have many odd-membered rings and large bond-angle deviation. The structures fabricated by the molecular-beam epitaxy method involve fewer floating bonds, smaller bond-angle deviations, and fewer six-membered rings in comparison with the melt-quenched structure. Through long-term annealing, both structures are transformed to the most stable structure as described by the Tersoff potential. It is also found that the continuous random network structure does not meet the Tersoff potential. Verification of the results through first-principle calculations shows that well-relaxed amorphous structure can be described by classical molecular dynamics despite the slightly large number of the floating bond and the overestimation of amorphous-phase energy.     

Nonlinear repetitive control with application to trajectory control of manipulators

In this article, a new control scheme named repetitive control is proposed for a class of nonlinear systems described by x(t) = Ax(t) + Bu(t) + n(x(t)) and y(t) = Cx(t), in which the controlled variables follow periodic reference commands. The stability condition is derived by applying the passivity theorem. We show how to apply the repetitive control scheme to the trajectory control of a manipulator. A simple repetitive control scheme is developed for the trajectory control of a manipulator by using nonlinear compensation and feedbacks of position and velocity signals. Experimental results for a three link manipulator verify that the proposed repetitive control reduces the tracking error to a very low level.