P53 is a critical tumor suppressor gene, activating p53 and its downstream targets to induce apoptosis is a promising way for cancer therapy. However, more than 50% of cancer patients have p53 mutations, which may cause cancer therapy resistance, and the underline mechanism is poorly understood. Here, we found that cell viability decrease and apoptosis induced by p53-dependent traditional drugs in colon cancer cells were eliminated in p53 mutant cells. Mutant p53 did not up-regulate the expression of its direct downstream targets PUMA and p21, due to the inhibition of PUMA transcription. Furthermore, mutant p53 could not bind to the promoter of PUMA to activate its transcription like WT p53 did, while overexpressed WT p53 rescued PUMA-induced subsequent apoptosis. In conclusion, our findings demonstrate mutant p53 may cause chemo-resistance of tumor because of inactivating PUMA transcription, which prompts some new insights for clinical therapy of cancer patients with mutant p53.
A wide range of semiotic resources has been used to construct meaning. Visual systems of meaning offer different resources and potentials for meaning making. Readers need to familiarize themselves with a variety of ways to make sense and read visual images. This paper, drawing on the theories of semiotics, art and visual communication grammar, presents a framework of interpretive strategies to approach, analyze and comprehend the visual images in contemporary multimodal texts, so as to expand the readers' interpretive repertoires and strengthen their capacity in constructing and interpreting multimodal texts.
Heating, Ventilation, and Air-Conditioning (HVAC) system that is almost indispensable service system of modern buildings is recognized as the most important engineering control measure against pandemics. However, the effectiveness of HVAC systems has been questioned on their ability to control airborne transmission. After the outbreak of COVID-19, China has controlled the spread within a relatively short period. Considering the large population, high population density, busy transportation and the overall underdeveloped economy, China’s control measures may have some implications to other countries, especially those with limited resources. This paper intends to provide a systematic summary of Chinese ventilation guidelines issued to cope with COVID-19 transmission. The following three aspects are the main focus of these guidelines: (1) general operation and management schemes of various types of HVAC systems, (2) operation and management schemes of HVAC system in typical types of buildings, and (3) design schemes of HVAC system of makeshift hospitals. In addition, some important differences in HVAC guidelines between China and other countries/institutions are identified and compared, and the possible reasons are discussed. Further discussions are made on the following topics, including the required fresh air supply, the extended operation time, the use of auxiliary equipment, the limited capacity of existing systems, and the use of personalized systems.
The subset-sum problem is a well-known non-deterministic polynomial-time complete (NP-complete) decision problem. This paper proposes a novel and efficient implementation of a parallel two-list algorithm for solving the problem on a graphics processing unit (GPU) using Compute Unified Device Architecture (CUDA). The algorithm is composed of a generation stage, a pruning stage, and a search stage. It is not easy to effectively implement the three stages of the algorithm on a GPU. Ways to achieve better performance, reasonable task distribution between CPU and GPU, effective GPU memory management, and CPU-GPU communication cost minimization are discussed. The generation stage of the algorithm adopts a typical recursive divide-and-conquer strategy. Because recursion cannot be well supported by current GPUs with compute capability less than 3.5, a new vector-based iterative implementation mechanism is designed to replace the explicit recursion. Furthermore, to optimize the performance of the GPU implementation, this paper improves the three stages of the algorithm. The experimental results show that the GPU implementation has much better performance than the CPU implementation and can achieve high speedup on different GPU cards. The experimental results also illustrate that the improved algorithm can bring significant performance benefits for the GPU implementation.well-known approach is the dynamic programming algorithm [7], which solves SSP in pseudopolynomial time, but it has exponential time complexity when the knapsack capacity is large. A tremendous improvement was made by Horowitz and Sahni [6], who developed a new technique that solves SSP in time O.n2 n=2 / with O.2 n=2 / memory space. The new technique is known as the two-list algorithm. On the basis of the two-list algorithm, Schroeppel and Shamir [8] proposed the two-list four-table algorithm, which needs the same time O.n2 n=2 / and less memory space O.2 n=4 / to solve SSP. Although many sequential algorithms have been designed to solve SSP in the past, Horowitz and Sahni's two-list algorithm continues to be the best known sequential algorithm.With the advent of parallel computing, a large effort has been made to reduce the computation time of SSP. Karnin [9] proposed a parallel algorithm that parallelizes the generation routine of the two-list four-table algorithm [8] using O.2 n=6 / processors and O.2 n=6 / memory cells in time O.n2 n=2 /. Ferreira [10] presented a brilliant parallel two-list algorithm that solves SSP in time O.n.2 n=2 / " / with O..2 n=2 / 1 " / processors and O.2 n=2 / memory space, where 0 6 " 6 1. Chang et al. [11] introduced a parallel algorithm that parallelizes the generation stage of Horowitz and Sahni's two-list algorithm [6]. They claimed that their parallel generation stage can be accomplished in time O..n=8/ 2 / with O.2 n=8 / processors and O.2 n=4 / memory space. On the basis of the generation technique of Chang et al., Lou and Chang [12] successfully parallelized the search stage of Horowitz and Sahni's two-list algorit...
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