Interaction of the disaccharides trehalose and gentiobiose with lipid bilayers: a comparative molecular dynamics study

The disaccharide α,α-trehalose (TRH) is known for its bioprotective action in organisms subject to stressful environmental conditions. However, the mechanisms whereby TRH stabilizes biomolecules remains matter of debate, the five main hypotheses being the water replacement (WRH), headgroup bridging (HBH), vitrification (VIH), water entrapment (WEH) and hydration forces (HFH) hypotheses. Four hypotheses (all except HFH) are in principle compatible with a preferential affinity of the sugar molecules (compared to water) for the biomolecular surface. According to the recently proposed sugar-like mechanism (Pereira and Hünenberger), preferential affinity would result from the entropy gain upon releasing many water molecules from the surface region to the bulk, at the cost of immobilizing and rigidifying fewer sugar molecules. Thus, a more flexible disaccharide such as gentiobiose (GNT) should evidence a weaker preferential affinity, limiting its bioprotective ability. In this work, molecular dynamics (MD) simulations of a dipalmitoyl-phosphatidylcholine (DPPC) bilayer patch in the presence of either pure water or aqueous solutions of GNT or TRH are performed in order to assess the validity of this suggestion. At 475 K and 1.6 m (molal), TRH indeed preserves the bilayer structure to a larger extent compared to GNT. However, the present investigation does not unambiguously indicate which of the above mechanism takes place, since the simulations reveal characteristic features of all of them. This suggests either that multiple mechanisms may be simultaneously active or that their definitions are not precise enough.     

Modelling the uncertainties in predicting produced water concentrations in the North Sea

A random walk model has been used to compute concentration distributions of dispersed oil in the North Sea resulting from produced water discharges. This formed part of a joint study commissioned by Statoil, OLF and BP International with modelling being undertaken by SINTEF and the Brixham Environmental Laboratory. The model has been set up using predicted tidal currents from the Norwegian Meteorological Office 20-km grid three-dimensional Continental Shelf model for the year 1990. Climatology data from the North Sea have been used to define the variation of the thermocline depth at monthly intervals over the year, and wind data from the East Shetland Basin have been used to compute the vertical mixing rates. Peak concentrations of dispersed oil were predicted to be approximately 3 μg l⁻¹ in the East Shetland Basin, assuming no biodegradation; this value is consistent with the measurements of Stagg et al. (In: Reed, M., Johnsen, S. (Eds), Produced Water 2, Environmental Issues and Mitigation Technologies, Plenum Press, 1996), where the data were collected in the immediate vicinity of the discharges and the effects of degradation would be expected to be negligible.A matrix of model runs was undertaken with different parameter values for the degradation of dispersed oil, horizontal and vertical mixing, and the mixing across the thermocline. These results were used to estimate the sensitivity of the model and the uncertainty in the predicted concentration fields. The results indicate that for the areas of high concentration, a band approximately 150-km wide stretching up the centre of the North Sea, parameterisation of the vertical mixing is most important for predicting the concentration levels. For areas more remote from the discharges and closer to the land masses, the degradation rate of material has most effect on predicted concentrations.     

Modelling of piezoelectric transducers applied to piezoelectric motors: a comparative study and new perspective

There has been a great deal of interest devoted to modelling and simulation of electromechanical transducers, and in particular to piezoelectric transducers, during the last decades. Modelling of the electro-mechanical phenomena is a complex matter: transducers comprise laminated structures of varying thickness, consideration of piezoelectric forcing, non-uniform electric field inside the ceramic … Several approaches for modelling the laminate structure have been reported, i.e. classical lamination theory, first order and higher order shear deformation theories. Likewise, the constitutive equations of the piezoelectric media have been included in FEA approaches. In addition, non-uniform electric fields, both linear and quadratic, were analysed. The particular case of travelling wave ultrasonic motors is addressed. This paper reports the comparative results of modelling all these plus additional transducer effects on the accuracy and presents the application to the classical electro-mechanical modelling of the stator of piezoelectric motors. Modelling results are compared with experimental data.     

针对华北地区地下水河湖生态补水成效的卫星遥感动态监测

为评估华北地区地下水超采治理河湖生态补水成效,基于现有国产卫星遥感影像覆盖能力,收集 2020 年华北地区 22 条(个)河湖流域卫星遥感动态监测影像数据,以相关水利基础数据为依据,构建一套完整的针对华北地区地下水河湖生态补水成效的水体遥感监测方案,将影像进行正射、融合、裁剪等预处理后,运用水体指数和深度学习 2 种方法对预处理后的遥感影像进行解译分析,提取河湖流域水面面积和有水河段长度,并结合河湖生态补水量进行验证,分析年内变化规律。监测结果表明：2020 年 7—12 月期间华北地区补水河湖水面面积和有水河段长度减少趋势减缓,并出现增加趋势。通过生态补水有利于缓解超采区水面面积减少趋势,验证通过统筹多种水源、调节时空布局,开展河湖回补地下水的方案是确有成效的。     

遥感技术在华北平原地下水资源潜力调查评估中的试点应用

在地下水资源日趋缺乏的太行山前河北平原,采用遥感技术开展地下水资源调查评价.在充分利用卫星遥感（ETM＋）图像数据反映地下水资源相关信息灵敏的基础上,综合其他常规资料,准确的圈定出山前冲洪积扇的范围,划分出它们的形成期次和扇体结构.明晰了不同河流扇体之间和同一河流不同期次扇体之间的空间交叠关系,恢复了主要河流的水流系统.详细解译出其他如古河道、地下水浅埋区、地下水溢出区、决口扇、消亡湖泊及其古三角洲等水文地质要素.在此基础上,推测出具有开采潜力的地下水富水区6处.在对其中的两处进一步开展详细的水文地质勘察后,被有关部门确认为极具开采潜力,可做为大型城市供水水源地.     

Modelling long-term C dynamics in croplands in the context of climate change: a case study from Ohio

A simple dynamic model (CBUDGET) was developed to quantify long-term carbon (C) dynamics in croplands. By using independent datasets (on continuous wheat) from the Waite Permanent Rotation Trial (Australia) and from Northwest Ohio, the tests of its performance resulted in R² values of 0.85 and 0.80, respectively, between observed and simulated values. Our model suggests that the rate of residual C addition into the soil is the primary factor that controls soil organic carbon (SOC) storage for Ohio croplands under continuous corn, wheat and oats for the period 1866–1996 and continuous soybean for the period of 1924–1996. The interaction of CO₂-fertilization and a temperature increase of 0.5°C decreased mean SOC levels for the selected crops over the same periods. A multiple linear regression model (MLR) relating carbon dioxide (CO₂) emissions to population growth, affluence and energy intensity with an R² of 0.99 indicates the significance of underlying causes of anticipated climate change. The MLR model thus serves to capture a more complete picture of anthropogenic sources of global climate change than considering agricultural activities only in exploring locally and regionally mitigative and preventive measures towards global climatic stability.     

潮土区不同质地土壤的养分动态变化研究

对华北平原大兴县 1 982— 2 0 0 0年两个时段大量土壤样本的分析结果表明 ,土壤养分含量与土壤质地表现出明显的一致性 ,体现了土壤质地越重 ,养分含量越高的特点 ;土壤质地对土壤养分含量的影响 ,1 982年的大于 2 0 0 0年的 ;但 2 0年来 ,由于土地利用集约度的增强 ,质地对土壤养分水平的影响渐趋减弱 ,不同质地土壤的养分水平渐趋一致     

Accuracy assessment of the ASTER GDEM and SRTM3 DEM: an example in the Loess Plateau and North China Plain of China

The digital elevation model (DEM) produced by the Shuttle Radar Topographic Mission (SRTM) has provided important fundamental data for topographic analysis in many fields. The recently released global digital elevation model (GDEM) produced by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) has higher spatial resolution and wider coverage than the SRTM3 DEM, and thus may be of more value to researchers. Taking two typical study areas—the Loess Plateau and the North China Plain of China—as an example, this article assesses the accuracy of the SRTM3 DEM and ASTER GDEM by collecting ground control points from topographical maps. It is found that both the SRTM3 DEM and the ASTER GDEM are far more accurate for the North China Plain than for the Loess Plateau. For the Loess Plateau, the accuracy of the ASTER GDEM is similar to that of the SRTM3 DEM; whereas for the North China Plain, it is much worse than that of the SRTM3 DEM. Considering the negative bias of the ASTER GDEM for flat or gentle regions, we improve its accuracy by adding the difference of the mean value between the SRTM3 DEM and ASTER GDEM for the North China Plain; then, the root mean square error (RMSE) of ±7.95 m from the original ASTER GDEM is improved to ±5.26 m, which demonstrates that it is a simple but useful way to improve the accuracy of the ASTER GDEM in flat or gentle regions.     

Stability and Scepticism in the Modelling of Doxastic States: Probabilities and Plain Beliefs

There are two prominent ways of formally modelling human belief. One is in terms of plain beliefs (yes-or-no beliefs, beliefs simpliciter), i.e., sets of propositions. The second one is in terms of degrees of beliefs, which are commonly taken to be representable by subjective probability functions. In relating these two ways of modelling human belief, the most natural idea is a thesis frequently attributed to John Locke: a proposition is or ought to be believed (accepted) just in case its subjective probability exceeds a contextually fixed probability threshold \(t<1\). This idea is known to have two serious drawbacks: first, it denies that beliefs are closed under conjunction, and second, it may easily lead to sets of beliefs that are logically inconsistent. In this paper I present two recent accounts of aligning plain belief with subjective probability: the Stability Theory of Leitgeb (Ann Pure Appl Log 164(12):1338–1389, 2013; Philos Rev 123(2):131–171, 2014; Proc Aristot Soc Suppl Vol 89(1):143–185, 2015a; The stability of belief: an essay on rationality and coherence. Oxford University Press, Oxford, 2015b) and the Probalogical Theory (or Tracking Theory) of Lin and Kelly (Synthese 186(2):531–575, 2012a; J Philos Log 41(6):957–981, 2012b). I argue that Leitgeb’s theory may be too sceptical for the purposes of real life.     

A comparative study of location-sharing privacy preferences in the United States and China

While prior studies have provided us with an initial understanding of people’s location-sharing privacy preferences, they have been limited to Western countries and have not investigated the impact of the granularity of location disclosures on people’s privacy preferences. We report findings of a 3-week comparative study collecting location traces and location-sharing preferences from two comparable groups in the United States and China. Results of the study shed further light on the complexity of people’s location-sharing privacy preferences and key attributes influencing willingness to disclose locations to others and to advertisers. While our findings reveal many similarities between US and Chinese participants, they also show interesting differences, such as differences in willingness to share location at “home” and at “work” and differences in the granularity of disclosures people feel comfortable with. We conclude with a discussion of implications for the design of location-sharing applications and location-based advertising.     

超(近)临界水溶剂特性的分子动力学模拟

采用分子动力学模拟,从溶解度参数的角度考察水在不同条件下的溶剂特性。计算结果表明水的溶解度参数1与温度成反比,但当温度高及723.15 K时,变化趋于平缓;2与压力成正比,在临界点(647.45 k,22 MPa)附近对压力特别敏感;超临界水的溶解度参数与密度有良好的线性关系。     

Modelling of healthcare-associated infections: a study on the dynamics of pathogen transmission by using an individual-based approach

Prevention and control of Healthcare Associated Infections (HAIs) has become a high priority for most healthcare organizations. Mathematical models can provide insights into the dynamics of nosocomial infections and help to evaluate the effect of infection control measures. The model presented in this paper adopts an individual-based and stochastic approach to investigate MRSA outbreaks in a hospital ward. A computer simulation was implemented to analyze the dynamics of the system associated with the spread of the infection and to carry out studies on space and personnel management. This study suggests that a strict spatial cohorting might be ineffective, if it is not combined with personnel cohorting.     

Cultural differences in social networking site use: A comparative study of China and the United States

This research compared social networking site (SNS) use in a collectivistic culture, China, and an individualistic culture, the United States (US). Over 400 college student participants from a Southwestern University in Chongqing, China, and 490 college participants from a Midwestern University in the US completed a survey about their use of SNSs – time spent, importance and motives for use. They then rated themselves on a variety of personal characteristics, namely the Big Five Personality factors, Loneliness, Shyness and Life Satisfaction. Results revealed cultural differences in SNS use. US participants spent more time in SNS, considered them to be more important and had more friends in SNSs than did Chinese participants. Self-ratings of personal characteristics also differed in the two cultures as did the personal characteristics that predicted SNS use. In general, personal characteristics were less effective in predicting SNS use in China than in the US. Findings suggest that in collectivistic cultures the importance of the family, friends and one’s groups may be partly responsible for Chinese participants’ lesser use of SNSs, whereas in individualistic cultures the importance of self and having more but less close and enduring friendships may be partly responsible for US participants’ greater use of SNSs. Personal characteristics predicted SNS use in both cultures but were stronger predictors in an individualistic culture than in a collectivistic, consistent with the emphasis on self in the former and on family, friends and one’s groups in the latter. Future research is needed to identify whether cultural values always take precedence over personal characteristics and motives in determining behavior in the virtual world.     

The role of multidimensional social capital in crowdfunding: A comparative study in China and US

How does an entrepreneur's social network impact crowdfunding? Based on social capital theory, we developed a research model and conducted a comparative study using objective data collected from China and the U.S. We found that an entrepreneur's social network ties, obligations to fund other entrepreneurs, and the shared meaning of the crowdfunding project between the entrepreneur and the sponsors had significant effects on crowdfunding performance in both China and the U.S. The predictive power of the three dimensions of social capital was stronger in China than it was in the U.S. Obligation also had a greater impact in China.     

Modelling and analysis of the dynamics of a tilting three-wheeled vehicle

To understand the handling behaviour of a three-wheeled tilting vehicle, models of the vehicle with different level of detail, corresponding to specific fields of investigation, have been developed. Then the proposed kinematics of the three-wheeler are assessed and optimized with respect to desired dynamic properties by applying a detailed multibody system model. The partially unstable nature of the motion of the vehicle suggests the application of an analytically derived, simplified model, to allow for focusing on stability aspects and steady-state handling properties. These investigations reveal the necessity of employing a steer-by-wire control system to support the driver by stabilizing the motion of the vehicle. Thus, an additional basic vehicle model is derived for control design, and an energy-efficient control strategy is presented. Numerical simulation results demonstrate the dynamic properties of the optimized kinematics and the control system, approved by successful test runs of a prototype.     

Image transforms as a tool for the study of soil salinity and alkalinity dynamics

Principal components analysis (PCA), ratioing, image differencing and intensity-hue-saturation (IHS) transformation have been widely used in monitoring various natural resources and environmental hazards. In our study, the temporal behaviour of salt-affected soils in the Indo-Gangetic alluvial plains of Uttar Pradesh has been studied using Landsat MSS data for 1975 and 1992. Apart from routine digital classification of temporal MSS data using Guassian maximum likelihood algorithm, PCA, image differencing, and ratioing were also evaluated for their potential in bringing out temporal changes in salt-affected soils, if any. The results indicate that the third principle component, image differencing, and ratioing of the first two MSS bands for two periods have brought out substantial information associated with the temporal behaviour of saltaffected soils.     

无人直升机遥感在华北平原地裂缝监测中的应用

本文介绍了无人直升机遥感技术在华北地裂缝(隆尧段)调查中的应用,给出了低空遥感地裂缝信息采集技术框架,并通过从不同角度、不同高度空中摄影方案,展示了部分遥感监测影像。根据华北平原(隆尧段)地裂缝的发育特征、建立遥感解译标志,并对隆尧地裂缝遥感信息进行探索性提取。通过野外验证,监测效果良好。本文研究成果为在平原地区快速、大面积寻找和监测地裂缝提供了可行的低空遥感技术和方法参考。     

华北平原小麦-玉米两熟作物区土壤培肥途径研究

研究了华北平原冬小麦、夏玉米轮作制度下不同施肥方式对土壤培肥的作用,进行了不同的秸秆、有机肥和无机化学肥料之间平衡配施的田间试验,结果表明,平衡施肥同时施用秸秆或有机肥后当年能显著增加土壤有机质、速效磷、速效钾含量。在较高肥力地块中"化肥平衡施肥 秸秆还田"的处理,土壤有机质比"不施肥、不还田"的对照增加最多,增加1.9gkg-1,增加率达8.9%;"平衡施肥 秸秆 快速腐解菌"的处理,土壤速效钾含量最高,为202.50gkg-1,比对照增加28.6%;在较低肥力地块中以"化肥平衡施肥 有机肥"土壤有机质、速效磷、速效钾增量最多,分别增加1.5gkg-1、6.9mgkg-1和32.5mgkg-1,增加率分别达11.7%、39.8%和36.1%。     

A comparative numerical study of hybrid-stabilized argon–water electric arc

The paper presents numerical simulations of the discharge and the near-outlet regions of the hybrid-stabilized argon–water electric arc. Two different numerical methods for solving the set of conservative equations for the continuity, momentum and energy have been applied. The major difference between the results using the two methods occurs in the temperature distribution in arc fringes within the discharge chamber. This fact influences the potential drop, overpressure, reabsorption of radiation and arc efficiency. It is shown that the radial profiles of temperature at the exit nozzle are less influenced by different temperature distribution within the discharge chamber. Comparison with chosen experimental temperature profiles shows very good agreement.     

Online consumer-to-consumer market in China – A comparative study of Taobao and eBay

China’s fast-growing online consumer-to-consumer (C2C) market merits widespread research efforts. However, it has so far received little research attention. In this exploratory study, we chose Taobao – a leading online C2C auction company in China with more than 70% of market shares – as our research context. We focus on the general market structure of Taobao in terms of three factors: market distribution, market growth, and market concentration. Based on these factors, we reveal the differences between Taobao and eBay. In our preliminary data analyses, we adopt total online reputation scores to measure the transaction volumes of online sellers. We also propose the sample-based Herfindal–Hirschman Index as a measure in the comparison of concentration levels between the two markets and at different time points. Our empirical data analyses suggest that online transaction volumes of Taobao sellers demonstrate many stochastic properties similar to those on eBay with some distinguishing properties, such as a faster growth rate but a lower concentration trend. We note that in 2006 Taobao sellers tended to maintain stabilized transaction volumes while market growth slowed. This reflects the effect of the competition in China’s online C2C market on Taobao’s performance.