Deep learning-based 3D in vivo dose reconstruction with EPID for MR-LINACs: A proof of concept study

Objective: To develop a novel deep learning-based 3D in vivo dose reconstruction framework with electronic portal imaging device (EPID) for magnetic resonance-linear accelerators (MR-LINACs). Approach: The proposed method directly back-projected 2D portal dose into 3D patient coarse dose, which bypassed the complicated patient-to-EPID scatter estimation step used in conventional methods. A pre-trained convolutional neural network (CNN) was then employed to map the coarse dose to the final accurate dose. The electron return effect caused by the magnetic field was captured with the CNN model. Patient dose and portal dose datasets were synchronously generated with Monte Carlo simulation for 96 patients (78 cases for training and validation and 18 cases for testing) treated with fixed-beam intensity-modulated radiotherapy in four different tumor sites, including the brain, nasopharynx, lung, and rectum. Beam angles from the training dataset were further rotated 2–3 times, and doses were recalculated to augment the datasets. Results: The comparison between reconstructed doses and MC ground truth doses showed mean absolute errors < 0.88% for all tumor sites. The averaged 3D γ-passing rates (3%, 2 mm) were 97.42%±2.66% (brain), 98.53%±0.95% (nasopharynx), 99.41%±0.46% (lung), and 98.63%±1.01% (rectum). The dose volume histograms and indices also showed good consistency. The average dose reconstruction time, including back projection and CNN dose mapping, was less than 3 s for each individual beam. Significance: The proposed method can be potentially used for accurate and fast 3D dosimetric verification for online adaptive radiotherapy using MR-LINACs.

The Effects from The U.S. and Japan to Emerging Stock Markets in Asia and Vietnam

The subprime mortgage crisis in the U.S. in mid-2008 suggests that stock prices volatility do spillover from one market to another after international stock markets downturn. The purpose of this paper is to examine the magnitude of return and volatility spillovers from developed markets (the U.S. and Japan) to eight emerging equity markets (India, China, Indonesia, Korea, Malaysia, the Philippines, Taiwan, Thailand) and Vietnam. Employing a mean and volatility spillover model that deals with the U.S. and Japan shocks and day effects as exogenous variables in ARMA(1,1), GARCH(1,1) for Asian emerging markets, the study finds some interesting findings. Firstly, the day effect is present on six out of nine studied markets, except for the Indian, Taiwanese and Philippine. Secondly, the results of return spillover confirm significant spillover effects across the markets with different magnitudes. Specifically, the U.S. exerts a stronger influence on the Malaysian, Philippine and Vietnamese market compared with Japan. In contrast, Japan has a higher spillover effect on the Chinese, Indian, Korea, and Thailand than the U.S. For the Indonesian market, the the return effect is equal. Finally, there is no evidence of a volatility effect of the U.S. and Japanese markets on the Asian emerging markets in this study.

How does transportation hub status promote the urban economic development? — the mediating effect analysis of innovation

A good traffic hub position has important significance for the development of a city, but it also strengthens the polarization effect, diffusion effect and return effect of the regional central cities for other cities. Does the development of urban hub economy strengthen or weaken these effects? Does hub effect also need other conditions to promote urban economic development? From the perspective of technological innovation, this paper analyses the mediating effect of technology absorption and innovation in the process of urban transportation hub promoting economic development. It is found that the people flow effect in the hub effect can better promote the economic development of cities through the mediating role of knowledge absorptive and innovative ability. In the influence of logistics effect on urban economic development, the mediating role of knowledge absorptive and innovative ability is not significant.

Innovative Design of an Elliptical Trainer with Right Timing of the Foot Trajectory

The existing elliptical trainer cannot provide the user with the real jogging exercising mode and does not meet the principles of ergonomics. The purpose of this paper is to propose and study an innovative elliptical trainer that imitates the right timing of the foot trajectory while jogging. First of all, this study proposes and illustrates the structure and function of the innovative elliptical trainer with quick-return effect. Then, by using vector-loop method and motion geometry of the mechanism, the proposed innovative mechanism is studied kinematically. A design example is presented for interpreting the design process. At last, the foot trajectory of the innovative elliptical trainer is analyzed and confirmed. The simulation results confirm that the timing of the foot trajectory of the foot support members satisfies the principles of ergonomics, and keeps the user’s legs from injury.

Dampak Pencatatandan Jatuh TempoWaran terhadap Harga Saham yang Disertai Waran di Indonesia

This research discusses the stock abnormal return effect of warrants to its underlying stock on its listing and maturity date. This study sample is the stock price changes of stocks backed with a warrant in the Indonesian stock market for the year 2008 to 2018—using an event study approach to observe stock abnormal return effect on the listing and maturity date of warrants. The results of this research are that we find a significant negative abnormal return around the warrants' listing date. On the warrants' expiration date, we find a significant negative effect before and after the money warrants' maturity date. However, a different result is obtained for the observation of out-of-the-money warrants that do not show any significant abnormal return on the event window.