Accelerating 3-D GPU-based Motion Tracking for Ultrasound Strain Elastography Using Sum-Tables: Analysis and Initial Results.

Now, with the availability of 3-D ultrasound data, a lot of research efforts are being devoted to developing 3-D ultrasound strain elastography (USE) systems. Because 3-D motion tracking, a core component in any 3-D USE system, is computationally intensive, a lot of efforts are under way to accelerate 3-D motion tracking. In the literature, the concept of Sum-Table has been used in a serial computing environment to reduce the burden of computing signal correlation, which is the single most computationally intensive component in 3-D motion tracking. In this study, parallel programming using graphics processing units (GPU) is used in conjunction with the concept of Sum-Table to improve the computational efficiency of 3-D motion tracking. To our knowledge, sum-tables have not been used in a GPU environment for 3-D motion tracking. Our main objective here is to investigate the feasibility of using sum-table-based normalized correlation coefficient (ST-NCC) method for the above-mentioned GPU-accelerated 3-D USE. More specifically, two different implementations of ST-NCC methods proposed by Lewis et al. and Luo-Konofagou are compared against each other. During the performance comparison, the conventional method for calculating the normalized correlation coefficient (NCC) was used as the baseline. All three methods were implemented using compute unified device architecture (CUDA; Version 9.0, Nvidia Inc., CA, USA) and tested on a professional GeForce GTX TITAN X card (Nvidia Inc., CA, USA). Using 3-D ultrasound data acquired during a tissue-mimicking phantom experiment, both displacement tracking accuracy and computational efficiency were evaluated for the above-mentioned three different methods. Based on data investigated, we found that under the GPU platform, Lou-Konofaguo method can still improve the computational efficiency (17-46%), as compared to the classic NCC method implemented into the same GPU platform. However, the Lewis method does not improve the computational efficiency in some configuration or improves the computational efficiency at a lower rate (7-23%) under the GPU parallel computing environment. Comparable displacement tracking accuracy was obtained by both methods

Effect of 1-MCP on storage quality and the mechanism involved in ethylene signal transduction in a new early-maturing apple variety ‘Taihangzaohong’ fruits during cold storage

1-Methylcyclopropene (1-MCP) can reduce the rate of fruit softening and prolong storage time. In this study, the fruit of a new early-maturing apple variety, ‘Taihangzaohong’, was treated with air (control), 2 μL/L 1-MCP, 100 μL/L ethylene (C 2H4) or 2 μL/L 1-MCP +100 μL/L C2H4 for 24 hours and then stored at 4 °C for 70 days. The postharvest physiological indices and the expression of 13 genes related to ethylene biosynthesis and signal transduction were monitored every 10 days. The results showed that 1-MCP can delay the softening rate and maintain the fruit quality of this early-maturing apple variety by reducing ethylene production by reducing the expression of MdACO1, MdACO2, and MdACS1, as well as by preventing ethylene signal transduction by decreasing the expression of MdETR2 and MdERS1 and increasing the expression of MdCTR1. Understanding the significant changes in these genes and their functions may help us explore the mechanisms controlling apple fruit softening and its response to exogenous 1-MCP and ethylene stimuli, as well as inhibition at the receptor level during ripening and senescence

Ecotourism, past, current and future perspectives : a bibliometric review between 2001 to 2018

Abstract: Ecotourism is natural based travel that conserves the environment, sustains the well-being of the local communities, and involves environmental interpretation and education. A number of literature reviews have been published focusing on specific aspects of the ecotourism market segmentation, ecological impacts of wildlife viewing, and community-based ecotourism, but there has been minimal attention to critical areas such as quality control, the industry, external environments or institutions. In order to further promote related studies, it is important to conduct a comprehensive review on ecotourism so that recent research progresses can be summarized and future research directions can be identified. Accordungly, this paper aims to conduct a bibliometric review on ecotourism to glean the past, current and future perspectives on ecotourism. Based on 1,889 articles published from 2001 to 2018 and searched from Web of Science, a systematic method combining bibliometric analysis and network analysis is applied to uncover the dynamic trends, academic collaboration and research hotspots. Results show that the overall publication quantity had been gradually improved. The key journals include Journal of Hospitality and Tourism Management, Annals of Tourism Research, Conservation Biology and Biological Conservation. Authors from USA have the most publications and international co-authorships, followed by Australia and England, while the most influential institution is the Chinese Academy of Science followed by Griffith University. Moreover, research keywords have been identified, including ecotourism, management, biodiversity, national park, sustainability and sustainable tourism. In order to further improve research in this field, it is crucial to combine different methods so that more innovative perspectives can be presented. Research findings from this study will provide limitations, and suggestions for future research