Identification of the AQP8-miR-92a network associated with the aggressive traits of colorectal cancer.

Even though earlier reports have revealed that Aquaporin 8 (AQP8) exert essential roles in diverse malignancies, its relationship between specific microRNAs (miRNAs) in regulation of colorectal carcinoma (CRC) progression has never been elaborated. Herein, we proved that AQP8 was downregulated in CRC and high level of AQP8 was significantly associated with better survival in CRC patients. Overexpression of AQP8 restrained CRC cell proliferation, migration and invasion capacities in vitro. In vivo, upregulation of AQP8 also suppressed CRC cell growth. Mechanistic analyses illustrated that AQP8 was a directly target of miR-92a. The expression of AQP8 was negatively modulated by miR-92a. Rescues analysis indicated that miR-92a facilitated CRC cell growth and invasion via modulating the expression of AQP8. Our work validated that miR-92a regulated the aggressiveness of CRC cell via targeting AQP8.

Physics of transportation: Towards optimal capacity using the multilayer network framework.

Because of the critical role of transportation in modern times, one of the most successful application areas of statistical physics of complex networks is the study of traffic dynamics. However, the vast majority of works treat transportation networks as an isolated system, which is inconsistent with the fact that many complex networks are interrelated in a nontrivial way. To mimic a realistic scenario, we use the framework of multilayer networks to construct a two-layered traffic model, whereby the upper layer provides higher transport speed than the lower layer. Moreover, passengers are guided to travel along the path of minimal travelling time and with the additional cost they can transfer from one layer to another to avoid congestion and/or reach the final destination faster. By means of numerical simulations, we show that a degree distribution-based strategy, although facilitating the cooperation between both layers, can be further improved by enhancing the critical generating rate of passengers using a particle swarm optimisation (PSO) algorithm. If initialised with the prior knowledge from the degree distribution-based strategy, the PSO algorithm converges considerably faster. Our work exemplifies how statistical physics of complex networks can positively affect daily life.

Optimal Allocation of Node Capacity in Cascade-Robustness Networks.

The robustness of large scale critical infrastructures, which can be modeled as complex networks, is of great significance. One of the most important means to enhance robustness is to optimize the allocation of resources. Traditional allocation of resources is mainly based on the topology information, which is neither realistic nor systematic. In this paper, we try to build a framework for searching for the most favorable pattern of node capacity allocation to reduce the vulnerability to cascading failures at a low cost. A nonlinear and multi-objective optimization model is proposed and tackled using a particle swarm optimization algorithm (PSO). It is found that the network becomes more robust and economical when less capacity is left on the heavily loaded nodes and the optimized network performs better resisting noise. Our work is helpful in designing a robust economical network.

Particle swarm optimization with scale-free interactions.

The particle swarm optimization (PSO) algorithm, in which individuals collaborate with their interacted neighbors like bird flocking to search for the optima, has been successfully applied in a wide range of fields pertaining to searching and convergence. Here we employ the scale-free network to represent the inter-individual interactions in the population, named SF-PSO. In contrast to the traditional PSO with fully-connected topology or regular topology, the scale-free topology used in SF-PSO incorporates the diversity of individuals in searching and information dissemination ability, leading to a quite different optimization process. Systematic results with respect to several standard test functions demonstrate that SF-PSO gives rise to a better balance between the convergence speed and the optimum quality, accounting for its much better performance than that of the traditional PSO algorithms. We further explore the dynamical searching process microscopically, finding that the cooperation of hub nodes and non-hub nodes play a crucial role in optimizing the convergence process. Our work may have implications in computational intelligence and complex networks.

Coveting thy neighbors fitness as a means to resolve social dilemmas.

In spatial evolutionary games the fitness of each individual is traditionally determined by the payoffs it obtains upon playing the game with its neighbors. Since defection yields the highest individual benefits, the outlook for cooperators is gloomy. While network reciprocity promotes collaborative efforts, chances of averting the impending social decline are slim if the temptation to defect is strong. It is, therefore, of interest to identify viable mechanisms that provide additional support for the evolution of cooperation. Inspired by the fact that the environment may be just as important as inheritance for individual development, we introduce a simple switch that allows a player to either keep its original payoff or use the average payoff of all its neighbors. Depending on which payoff is higher, the influence of either option can be tuned by means of a single parameter. We show that, in general, taking into account the environment promotes cooperation. Yet coveting the fitness of one's neighbors too strongly is not optimal. In fact, cooperation thrives best only if the influence of payoffs obtained in the traditional way is equal to that of the average payoff of the neighborhood. We present results for the prisoner's dilemma and the snowdrift game, for different levels of uncertainty governing the strategy adoption process, and for different neighborhood sizes. Our approach outlines a viable route to increased levels of cooperative behavior in structured populations, but one that requires a thoughtful implementation.

Evolution of Chinese airport network.

With the rapid development of the economy and the accelerated globalization process, the aviation industry plays a more and more critical role in today's world, in both developed and developing countries. As the infrastructure of aviation industry, the airport network is one of the most important indicators of economic growth. In this paper, we investigate the evolution of the Chinese airport network (CAN) via complex network theory. It is found that although the topology of CAN has remained steady during the past few years, there are many dynamic switchings inside the network, which have changed the relative importance of airports and airlines. Moreover, we investigate the evolution of traffic flow (passengers and cargoes) on CAN. It is found that the traffic continues to grow in an exponential form and has evident seasonal fluctuations. We also found that cargo traffic and passenger traffic are positively related but the correlations are quite different for different kinds of cities.

Do younger female breast cancer patients have a poorer prognosis? Results from a population-based survival analysis.

Younger women who develop breast cancer are hypothesized to have poorer survival rates than women who develop it at a later stage in life. Several studies have suggested that differences in biologic characteristics of breast cancer in younger (premenopausal) and older (postmenopausal) women may account for the prognostic variation. This population-based cohort study reports on survival rates of breast cancer in Singapore and examines the hypothesis that younger breast cancer patients have a poorer prognosis. A total of 6,397 breast cancer patients diagnosed from 1968 to 1992 were identified from the population-based cancer registry and followed up through 1997. Outcome measures were relative survival rates (RSRs) calculated using Hakulinen's method and excess hazards ratios (HRs) derived from a regression model based on relative survival. The 2-, 5- and 10-year RSRs were worse among those aged > 75 (65%, 48% and 39%, respectively). The best survival rates were seen among those aged 40-44 (84%, 67% and 56%). Patients younger than 35 years faired reasonably well (79%, 60% and 50%). When the data were stratified according to clinical stage and calendar year, the highest risk of excess deaths was found in women > or = 75 years old. In patients with localized cancer and/or regional metastases, those in the 35-39 age group had the lowest excess risk. In patients with distant metastases, those younger than 35 years of age had the lowest excess risk of death. At the population level, younger women (< 45 years) with breast cancer in Singapore have higher relative survival rates.

Population-based survival for cervical cancer in Singapore, 1968-1992.

OBJECTIVE: The aim of this study was to describe the cervical cancer survival rates in Singapore during the period of 1968 through 1992 using population-based data. STUDY DESIGN: A review of cases with cervical cancer diagnosed between 1968 and 1992 from Singapore Cancer Registry was conducted. Information on vital status at December 31, 1997, was available for 3531 cases. Cumulative observed and relative survival rates were computed by using Hakulinen's method. RESULTS: Survival in cervical cancer in Singapore has improved over the 25-year period. The overall 5-year age-standardized relative survival (ASRS) for all patients increased from 45% in 1968-1972 to 65% in 1988-92. Poorer survival rates were observed in elderly patients and Malays. CONCLUSION: The improvement in survival of cervical cancer is likely to be attributed to the rapid national development of Singapore, resulting in the improvements in health services infrastructure and accessibility, as well as to the impact of widely available cytology-based screening resulting in early detection.

Population-based survival analysis of colorectal cancer patients in Singapore, 1968-1992.

Since the 1980s, colorectal cancer incidence in Singapore has ranked second to lung in males and females. We describe a population-based analysis of survival of colorectal cancer patients diagnosed from 1968 to 1992 in Singapore. Data of colorectal cancer patients diagnosed during 1968-1992 were retrieved from the Singapore Cancer Registry. Patients were passively followed up for death to the end of 1997. The final dataset consisted of 10,114 subjects. Observed and relative survival rates were calculated by stage (localized, regional metastases and distant metastases), age, ethnicity and calendar period for both genders. Over the study period, a significant progress in survival of colorectal cancer patients was observed. For localized cancer of the colon, the 5-year age-standardized relative survival (ASRS) increased from 36% in 1968-1972 to 66% in 1988-1992 for males and from 32 to 71% for females. For localized rectal cancer, the 5-year ASRS improved from 25 to 66% for males and from 23 to 66% in females. Similarly, improvement was observed in colorectal cancer patients with regional metastases, but not in those with distant metastases. Calendar year period and clinical stage of disease were identified as major significant prognostic factors of survival for colorectal cancer. The substantially improved colorectal cancer survival rates reflected the interplay of cancer control activities in various areas, such as health promotion, early diagnosis and treatment. Our study shows a unique changing pattern of survival experience for colorectal patients from a country undergoing rapid economic development.