c-axis preferential orientation of hydroxyapatite accounts for the high wear resistance of the teeth of black carp (Mylopharyngodon piceus)

Biological armors such as mollusk shells have long been recognized and studied for their values in inspiring novel designs of engineering materials with higher toughness and strength. However, no material is invincible and biological armors also have their rivals. In this paper, our attention is focused on the teeth of black carp (Mylopharyngodon piceus) which is a predator of shelled mollusks like snails and mussels. Nanoscratching test on the enameloid, the outermost layer of the teeth, indicates that the natural occlusal surface (OS) has much higher wear resistance compared to the other sections. Subsequent X-ray diffraction analysis reveals that the hydroxyapatite (HAp) crystallites in the vicinity of OS possess c-axis preferential orientation. The superior wear resistance of black carp teeth is attributed to the c-axis preferential orientation of HAp near the OS since the (001) surface of HAp crystal, which is perpendicular to the c-axis, exhibits much better wear resistance compared to the other surfaces as demonstrated by the molecular dynamics simulation. Our results not only shed light on the origin of the good wear resistance exhibited by the black carp teeth but are of great value to the design of engineering materials with better abrasion resistance

Persistence Parameter: a Reliable Measurement for Behavioral Responses of Medaka (Oryzias latipes) to Environmental Stress

Online monitoring systems provided a significant evidence for feasibility of the stepwise behavioral response model in detecting the effects of organophosphorus pesticides on movements of medaka (Oryzias latipes), being able to determine the state of indicator organisms, "no effect," "stimulation," "acclimation," "adjustment (readjustment)," and "toxic effect." Though the stepwise behavioral response model postulated that an organism displays a time-dependent sequence of compensatory stepwise behavioral response during exposure to pollutants above their respective thresholds of resistance, it was still a conceptual model based on tendency only in analysis. In this study, the phenomenon of bacterial persistence was used to interpret the relationship between the stepwise behavioral response model and the environmental stress caused by both exposure time and different treatments. Quantitative measurements of the stepwise behavioral response model led to a simple mathematical description of the threshold switch, which evaluated the effects of environmental stress on behavioral responses to decide the tendency. The adjustment ability correlated to "persisters (p)" is very important for test individuals to overcome the "threshold" from the outside environmental stress. The computational modeling results suggested that "persister (p)," as described in the general equations of bacterial persistence model in changing environments, illustrated behavior acclimation and adjustment (or readjustment) clearly. Consequently, the persistence parameter, p, was critical in addressing for medaka to be adapted to fluctuating environments under different environmental stress

Pan-cancer analysis of whole genomes

Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale(1-3). Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter(4); identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation(5,6); analyses timings and patterns of tumour evolution(7); describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity(8,9); and evaluates a range of more-specialized features of cancer genomes(8,10-18).Peer reviewe

Neural-adaptive constrained flight control for air ground recovery under terrain obstacles

This article contrives a neural-adaptive constrained controller of the cable towed air-ground recovery system subject to terrain obstacles, unmeasurable cable tensions, trailing vortex, wind gust, and actuator saturation. In air-ground recovery system modeling, the towed vehicle's nominal 6 DOF affine nonlinear dynamics and the cable system's finite links-joints dynamics are formulated. To achieve accurate air-ground recovery under terrain obstacles, an asymmetric barrier Lyapunov function-based flight controller of the towed vehicle is proposed, by transforming the terrain obstacles into time-varying constraints on the vehicle's trajectory. Then, to approximate the towed vehicle's lumped unknown dynamics caused by the unmeasurable cable tensions and airflows, several echo state network (ESN) approximators are established for velocity and attitude subsystems. By using the state approximation errors-based neural weights learning strategy and minimal learning parameter technique, these ESNs possess better transient behaviors and lower online computational burden. Furthermore, the actuator saturation is automatically monitored and released, by incorporating a specially designed auxiliary compensating system into the angular rate control law for compensation. The stability of the closed-loop system is analyzed. Finally, numerical simulations under two air-ground recovery scenarios are performed to demonstrate the performance of the proposed controller.Transport and Plannin

Magnetization dynamics in hybrid nanostructures

Applied Science

Facilitating social interaction: Neighborhood revitalization strategy of Shanghai Cannes

This project is about the neighborhood revitalization of Shanghai Cannes, which is a problematic suburban high-density neighborhood in Shanghai. The research itself is a spatial analysis on different scales and mapping of current social networks. The future strategy and design will mainly focus on how to regenerate neighborhood living environment that facilitate social interaction on different scale in order to strengthen the sense of community in Shanghai Cannes.Design as politicsUrbanismArchitectur

Robustness of complex networks: Theory and application

Failures of networks, such as power outages in power systems, congestions intransportation networks, paralyse our daily life and introduce a tremendous cascading effect on our society. Networks should be constructed and operated in a robust way against random failures or deliberate attacks.We study how to add a single link into an existing network such that the robustness of the network is maximally improved among all the possibilities. A graph metric, the effective graph resistance, is employed to quantify the robustness of the network. Though exhaustive search guarantees the optimal solution, the computational complexity is high and is not scalable with the increase of network size. We propose strategies that take into account the structural and spectral properties of networks and indicate links whose addition result in a high robustness level.Network Architectures and Service

Inner-city station areas in Chinese cities

Redevelopments of Chinese inner-­?city station areas introduced both new transport infrastructures (high speed railway, urban mass transit system, etc.) and real estate projects to station vicinities during the past decades. However, existing station areas are isolated from the rest of the city, and seldom urban activities take place in station surroundings. This paper aims at exploring mechanisms behind the emergence of “urban isolation”. To this end, four relevant topics are discussed, namely urbanization in China, travel model shift in and between big cities, railway station operation and planning philosophy of inner?city station areas. Examining above aspects in some China’s big cities, especially in two typical station areas, Beijing West and Tianjin station areas, this paper examines why Chinese inner?city station areas have gained an increasing role as transport nodes but have paradoxically become isolated enclaves in city centers. Two recommendations are also generated out of above review and analysis.ArchitectureArchitecture and The Built Environmen

Improving Global Tide and Storm Surge Forecasts with Parameter Estimation

Coastal flooding is threatening the personal safety, property, and social development of the low-lying land around the coast worldwide. Stormsurge is one of the main sources of coastal flooding. Tide and surge models can provide timely water level forecasts for coastal management with the early warning of flooding. Although a regional model can be used to study effects of climate change in a specific area, global water level modeling provides some advantages, such as the long-term response of the extreme sea level and coastal flooding due to global warming and comparison of global surge differences between regions. Global hydrodynamic modeling is becoming an increasingly important research topic. Nowadays, with ever increasing resolution, neglected physical processes and parameter uncertainties due to the inaccurate input or empirical values is becoming more and more dominating the model accuracy. At the same time, measurements like the satellite altimeter and the in-situ tide gauges are able to monitor the water level changes, which offers the possibility to estimate uncertain parameters. In this thesis, we develop a parameter estimation scheme and implement it to a global tide and surge model, and subsequently, apply to improve the water level forecast skill. Themain challenges for large-scale parameter assimilation for tide models are in assessing parameter uncertainties, large computational demand, large memory requirement and insufficient observations. In this thesis, we explore these challenges using an application to the Global Tide and Surge Model (GTSM). A computationally efficient and low memory usage iterative estimation scheme is designed and applied to GTSM for bathymetry and bottomfriction coefficient calibration. In addition, we study how to make the best use of spatial sparse distributed observations...Mathematical Physic