Finite element modelling of skeletal muscles coupled with fatigue

In this study, Hill's muscle theory coupled with fatigue was proposed to describe mechanical behaviours of skeletal muscles. The force developed by a fatigued muscle was described by a muscle fatigue formula which was a time function of the activation α_a and the stretch λ. The modified Hill's muscle theory was hence incorporated into a three-dimensional (3D) finite element model using the PAK finite element code. In this paper, the theoretical derivation of the 3D muscle model was firstly described. After presenting the method of establishing the finite element programme, a case example of studying the mechanical response of a frog gastrocnemius muscle was used to illustrate the applicability of the proposed methodology. The effects of the muscle fatigue on the deformation as well as the stress and strain distribution of the frog muscle subject to a cyclic activation function have been determined. An experiment capturing the real-time shape change of a frog muscle was also conducted to assess the applicability of the proposed method. A comparison between the deformed shapes of the predictive model and the frog muscles was also made. It was shown that the method is capable of providing a reasonable model for describing the mechanical behaviour of skeletal muscles.     

Volatility dynamics of the US business cycle: A multivariate asymmetric GARCH approach

Most empirical investigations of the business cycles in the United States have excluded the dimension of asymmetric conditional volatility. This paper analyses the volatility dynamics of the US business cycle by comparing the performance of various multivariate generalised autoregressive conditional heteroskedasticity (GARCH) models. In particular, we propose two bivariate GARCH models to examine the evidence of volatility asymmetry and time-varying correlations concurrently, and then apply the proposed models to five sectors of Industrial Production of the United States. Our findings provide strong evidence of asymmetric conditional volatility in all sectors, and some support of time-varying correlations in various sectoral pairs. This has important policy implications for government to consider the effective countercyclical measures during recessions.     

Short-channel metal-gate TFTs with modified Schottky-barrier source/drain

A thin active layer, a fully silicided source/drain (S/D), a modified Schottky-barrier, a high dielectric constant (high-/spl kappa/) gate dielectric, and a metal gate are integrated to realize high-performance thin-film transistors (TFTs). Devices with 0.1-/spl mu/m gate length were fabricated successfully. Low threshold voltage, low subthreshold swing, high transconductance, low S/D resistance, high on/off current ratio, and negligible threshold voltage rolloff are demonstrated. It is thus suggested for the first time that the short-channel modified Schottky-barrier TFT is a solution to carrier out three-dimension integrated circuits and system-on-panel.     

Geometry of single axis motions using conic fitting

Previous algorithms for recovering 3D geometry from an uncalibrated image sequence of a single axis motion of unknown rotation angles are mainly based on the computation of two-view fundamental matrices and three-view trifocal tensors. We propose three new methods that are based on fitting a conic locus to corresponding image points over multiple views. The main advantage is that determining only five parameters of a conic from one corresponding point over at least five views is simpler and more robust than determining a fundamental matrix from two views or a trifocal tensor from three views. It is shown that the geometry of single axis motion can be recovered either by computing one conic locus and one fundamental matrix or by computing at least two conic loci. A maximum likelihood solution based on this parametrization of the single axis motion is also described for optimal estimation using three or more loci. The experiments on real image sequences demonstrate the simplicity, accuracy, and robustness of the new methods.     

Extended latent class models for collaborative recommendation

With the advent of the World Wide Web, providing just-in-time personalized product recommendations to customers now becomes possible. Collaborative recommender systems utilize correlation between customer preference ratings to identify "like-minded" customers and predict their product preference. One factor determining the success of the recommender systems is the prediction accuracy, which in many cases is limited by lacking adequate ratings (the sparsity problem). Recently, the use of latent class model (LCM) has been proposed to alleviate this problem. In this paper, we first study how the LCM can be extended to handle customers and products outside the training set. In addition, we propose the use of a pair of LCMs (called dual latent class model-DLCM), instead of a single LCM, to model customers' likes and dislikes separately for enhancing the prediction accuracy. Experimental results based on the EachMovie dataset show that DLCM outperforms both LCM and the conventional correlation-based method when the available ratings are sparse.     

Detection of coagulating blood under steady flow by statistical analysis of backscattered signals

The main purpose of this study is to detect blood coagulation under flow condition by analyzing Nakagami statistical model of backscattered signals. The radiofrequency (RF) signals backscattered from flowing blood were measured with a 10-MHz focused transducer. A 30 ml aliquot of blood was circulated in the flow model, and 3 ml of 0.5 M calcium chloride solution was added to induce blood coagulation. The progression in the blood coagulation due to the addition of the calcium chloride solution resulted in the integrated backscatter being increased by 4.2 +/- 0.5 dB, then tended to stabilize as the clot was formed. The Nakagami parameter was approximately 0.75 +/- 0.1 for flowing blood during the initial stage of blood coagulation, and it increased rapidly to its highest level of 2.6 +/- 0.5 during clotting. These experimental results demonstrate the feasibility of using the ultrasonic statistical parameter for detecting blood coagulation from flowing blood and provide a novel method for further monitoring the progress of clotting and thrombosis in vivo.     

Evaluating p97 Inhibitor Analogues for Potency against p97–p37 and p97–Npl4–Ufd1 Complexes

We previously found that the p97 cofactor, p47, significantly decreased the potency of some ATP‐competitive p97 inhibitors such as ML240 [2‐(2‐amino‐1H‐benzo[d]imidazol‐1‐yl)‐N‐benzyl‐8‐methoxyquinazolin‐4‐amine] and ML241 [2‐(2H‐benzo[b][1,4]oxazin‐4(3H)‐yl)‐N‐benzyl‐5,6,7,8 tetrahydroquinazolin‐4‐amine]. In this study, we aimed to evaluate inhibitor potencies against two additional p97 cofactor complexes, p97–p37 and p97–Npl4–Ufd1. We focused on these two cofactor complexes, because the protein sequence of p37 is 50 % identical to that of p47, and the Npl4–Ufd1 heterodimer (NU) is the most‐studied p97 cofactor complex. We screened 200 p97 inhibitor analogues for their ability to inhibit the ATPase activity of p97 alone and of p97–p37 and p97–NU complexes. In contrast to the effect of p47, p37 and NU did not significantly change the potencies of most of the compounds. These results highlight differences among p97 cofactors in influencing p97 conformation and effects of inhibitors on p97 complexes, as compared to p97 alone. Continued efforts are needed to advance the development of complex‐specific p97 inhibitors.     

Attenuation compensation for cardiac single-photon emission computed tomographic imaging: Part 1. Impact of attenuation and methods of estimating attenuation maps

Attenuation is believed to be one of the major causes of false-positive cardiac single-photon emission computed tomographic (SPECT) perfusion images. This article reviews the physics of attenuation, the artifacts produced by attenuation, and the need for scatter correction in combination with attenuation correction. The review continues with a comparison of the various configurations for transmission imaging that could be used to estimate patient specific attenuation maps, and an overview of how these are being developed for use on multiheaded SPECT systems, including discussions of truncation, noise, and spatial resolution of the estimated attenuation maps. Ways of estimating patient specific attenuation maps besides transmission imaging are also discussed.