Innovation, imitation, and problem-solving in a networked group

We implemented a problem-solving task in which groups of participants simultaneously played a simple innovation game in a complex problem space, with score feedback provided after each of a number of rounds. Each participant in a group was allowed to view and imitate the guesses of others during the game. The results showed the use of social learning strategies previously studied in other species, and demonstrated benefits of social learning and nonlinear effects of group size on strategy and performance. Rather than simply encouraging conformity, groups provided information to each individual about the distribution of useful innovations in the problem space. Imitation facilitated innovation rather than displacing it, because the former allowed good solutions to be propagated and preserved for further cumulative innovations in the group. Participants generally improved their solutions through the use of fairly conservative strategies, such as changing only a small portion of one's solution at a time, and tending to imitate solutions similar to one's own. Changes in these strategies over time had the effect of making solutions increasingly entrenched, both at individual and group levels. These results showed evidence of nonlinear dynamics in the decentralization of innovation, the emergence of group phenomena from complex interactions of individual efforts, stigmergy in the use of social information, and dynamic tradeoffs between exploration and exploitation of solutions. These results also support the idea that innovation and creativity can be recognized at the group level even when group members are generally cautious and imitative.     

Vortex dynamics over a dihedral plane in a transitional slightly compressible flow: a computational study

In this paper, three different vortex diagnostic methods are compared to obtain a better understanding of boundary layer influence on the transport of vortical structures involving a complete analysis of vorticity, the Vorticity Threshold Criterion (VTC), and the Weiss Criterion (WC). These three techniques are basically confronted to find a suitable understanding of all flow characteristics (the swirling dynamics produced downstream of the discontinuity point of the dihedral) for a range of laminar to transitional Reynolds numbers. The computations on this dihedral plane are made using a 2D DNS method. The Weiss criterion, coming from the analysis of the incompressible Euler equations is validated and applied to low speed compressible flows (M=0.2). A detailed analysis of the swirling procedure is performed for Reynolds numbers 242, 400 (laminar), 565 and 800 (transitional). Finally, different averaged or instantaneous, local or global quantities are used to analyse and characterize Concentrated Structures as a function of the Reynolds number evolution.     

Acoustic cloaking: Geometric transform,homogenization and a genetic algorithm

A general process is proposed to experimentally design anisotropic inhomogeneous metamaterials obtained through a change of coordinates in the Helmholtz equation. The method is applied to the case of a cylindrical transformation that allows cloaking to be performed. To approximate such complex metamaterials we apply results of the theory of homogenization and combine them with a genetic algorithm. To illustrate the power of our approach, we design three types of cloaks composed of isotropic concentric layers structured with three types of perforations: curved rectangles, split rings and crosses. These cloaks have parameters compatible with existing technology and they mimic the behavior of the transformed material. Numerical simulations have been performed to qualitatively and quantitatively study the cloaking efficiency of these metamaterials.     

Where there's a web,there's a way: commercial genetic testing and the Internet

The Internet has become a "global marketplace", enabling consumers to purchase health care products and services, including genetic testing, through a variety of national and international sources. A web search for commercial (for-profit) genetic testing companies found 12 with a web presence that were offering adult genetic susceptibility testing, of which 3 offered direct-to-consumer access. In this paper, Canada--with its educated population and universal health care system--will serve as a case study for illustrating the social, ethical and policy issues (e.g., information privacy, just access to health care, product safety, and access to unbiased health information) arising with Internet-based access to commercial genetic testing. Health professionals, policy makers and consumers in all developed nations will be faced with complex technical, social and ethical issues, but without further discussion it will not be possible to determine how best to manage and maximise the benefits of this increased accessibility and choice, while minimising the associated personal and social costs.     

Screening for C283Y gamma-sarcoglycan mutation in a high-risk group of Bulgarian Gypsies: evidence for a geographical localization and a non-random distribution among Gypsy subgroups

Limb-girdle muscular dystrophy type 2C (LGMD2C) is an autosomal recessive disorder caused by mutations in the gamma-sarcoglycan gene. A 'private' Gypsy C283Y mutation was detected in this gene. Recently, a number of LGMD2C-affected families belonging to a Xoroxane Gypsy group have been detected in eastern Bulgaria and all of these cases were due to the same mutation. We have screened 300 unrelated individuals of reproductive age from this high-risk Xoroxane Gypsy group, settled in Sliven. The genetic test by PCR-SSCP analysis for the C283Y mutation revealed a carrier frequency of 7.7%. The screened sample was ethnically not homogeneous. It was divided in ethnonym groups on the basis of social and economic status, language characteristics and trades. We found that the C283Y was not randomly distributed among the Gypsy subgroups. The disease seemed to be limited to the Xoroxane Gypsy group and geographically localized in eastern Bulgaria.     

Transmission dynamics of novel coronavirus SARS-CoV-2 among healthcare workers,a case study in Iran

One of the main concerns during the COVID-19 pandemic was the protection of healthcare workers against the novel coronavirus. The critical role and vulnerability of healthcare workers during the COVID-19 pandemic leads us to derive a mathematical model to express the spread of coronavirus between the healthcare workers. In the first step, the SECIRH model is introduced, and then the mathematical equations are written. The proposed model includes eight state variables, i.e., Susceptible, Exposed, Carrier, Infected, Hospitalized, ICU admitted, Dead, and finally Recovered. In this model, the vaccination, protective equipment, and recruitment policy are considered as preventive actions. The formal confirmed data provided by the Iranian ministry of health is used to simulate the proposed model. The simulation results revealed that the proposed model has a high degree of consistency with the actual COVID-19 daily statistics. In addition, the roles of vaccination, protective equipment, and recruitment policy for the elimination of coronavirus among the healthcare workers are investigated. The results of this research help the policymakers to adopt the best decisions against the spread of coronavirus among healthcare workers.

     

Lie group analysis for thermophoretic and radiative augmentation of heat and mass transfer in a Brinkman-Darcy flow over a flat surface with heat generation

A boundary layer analysis is presented to investigate numerically the effects of radiation,thermophoresis and the dimensionless heat generation or absorption on hydromagnetic flow with heat and mass transfer over a flat surface in a porous medium.The boundary layer equations are transformed to non-linear ordinary differential equations using scaling group of transformations and they are solved numerically by using the fourth order Runge-Kutta method with shooting technique for some values of physical parameters.Comparisons with previously published work are performed and the results are found to be in very good agreement.Many results are obtained and a representative set is displayed graphically to illustrate the influence of the various parameters on the dimensionless velocity,temperature and concentration profiles as well as the local skin-friction coefficient,wall heat transfer,particle deposition rate and wall thermophoretic deposition velocity.The results show that the magnetic field induces acceleration of the flow,rather than deceleration(as in classical magnetohydrodynamics(MHD) boundary layer flow) but to reduce temperature and increase concentration of particles in boundary layer.Also,there is a strong dependency of the concentration in the boundary layer on both the Schmidt number and mass transfer parameter.     

Three-dimensional boundary layer and vortex wake over a cone at high angle of attack: study of asymmetries

An experimental investigation of the flow over a one at a large angle of attack is reported. First, the study was focused on the wall shear stress measurement, including the localization of the separation. Secondly, the mean flow field in the whole wake of the cone was measured, as well as the velocity fluctuations. Results indicate that the separation and the fluctuations are asymmetrical in a certain way, whereas the mean flow field is approximately symmetrical. Finally, the different parts of the flow can be easily determined using vorticity calculations.List of symbols C vortex core - D diffusion coefficient for the polarographic solution - D cone diameter for the rotation plane of the electrochemical probes - D separation point - F function F (sin ) = (K ₁-K ₂)/(K ₁+K ₂) - G function G(sin ) = (K ₁+K ₂)/(K ₁+K ₂)( = 90dg) - g bidimensional gain of the electrochemical probe (constant for each probe) - K ₁, K ₂ mass transfer coefficients for differential probes - Re _x Reynolds number based on the X length, and relative to the forward upstream velocity - wall velocity gradient vector - S wall velocity gradient modulus - S enclosing saddle point - S _x azimuthal component of the wall velocity gradient (perpendicular to a generator) - S _z longitudinal component of the wall velocity gradient (along a generator) - U mean value of the forward upstream velocity - U _i component number i of the velocity vector in the (X, Y, Z) coordinates - X, Y, Z cone cartesian coordinates - non-dimensional cone cartesian coordinates (relative to D) Greek symbols incidence (part 1) angle between the wall velocity gradient and the neutral axis of the electrochemical probe (except part 1) - _r relative incidence /0 _c - velocity circulation - wavelength of the laser beam - kinematic viscosity - azimuthal angle - _c cone semi-apex angle     

力学研究中"大数据"的启示、应用与挑战

大数据在全世界发展迅猛, 应用成效显著.大数据独特的思维和方法, 为科学研究与探索提供了全新的范式.力学研究中,高时空分辨率、多参数同步观测与高精度、大规模模拟手段的发展,为力学大数据的发展提供了契机,大数据、机器智能方法的应用正呈现快速上升趋势.本文旨在分析大数据思维方法在力学研究中的应用, 及其启示与挑战.首先从大数据资源、大数据科学及大数据技术3个层面分析了大数据的内涵及研究态势,概括了国内外政府及组织机构的大数据发展规划.而后对比分析了力学思维方法与大数据思维方法的特点,指出两者的本质区别在于数据使用方式的不同而带来的范式差异:大数据采用数据驱动模型替代力学中的偏微分方程组以描述问题,在复杂系统的分析、预测中优势显著.回顾了大数据方法在材料性能预测、材料本构建模、湍流建模、结构健康监测及试验力学等方面的最新研究进展,以及动态数据驱动与数字孪生等大数据驱动的建模模拟新范式.总结了大数据在力学研究中应用的3种方式, 即驱动已有模型改进,挖掘复杂隐含的规律, 以及替代已有的理论方法等. 最后,建议以力学研究为主体和牵引, 大数据与力学双驱动,推动大数据与力学交叉形成理论与方法突破、及学科发展新方向.      

Transition,turbulence and oscillating flow in a pipe a visual study

Transitional and turbulent oscillatory flow in a rigid pipe with long entry sections was investigated using flow visualization to establish the existence of coherent structures. Flow tracer and high speed motion pictures were used. The simple harmonic motion of a scotch yoke and flywheel linked to a piston and cylinder provided the flow driving force. The camera was convected with the flow by attaching it through a gearing system to the scotch yoke.List of symbols A cross sectional area of flow - C, K constants - D pipe diameter - N _Re,ave Reynolds number based on average velocity (DU _ave /v) - N _Re,p Reynolds number based on maximum oscillatory velocity (DU _max /v) - Reynolds number based on maximum oscillatory velocity and Stokes (boundary) layer thickness (U _max /v) - R pipe radius - U instantaneous velocity in the flow direction - short-term average instantaneous velocity - U ^* friction velocity (U _ave (f/2)^1/2) - U _amp amplitude parameter (U _max /U _ave ) - U _ave average velocity - U _s steady velocity - U _t instantaneous oscillatory velocity - U _max maximum oscillatory velocity ( X _max /T) - u _r , u _z deviations from _r, and _z - y radial coordinate from wall (R–r) - y ⁺ dimensionless radial coordinate from wall (y U*/v) - frequency parameter [R (/v) ^1/2] - Stokes (boundary) layer thickness [C (2 v/)^1/2] - normalized time into cycle - fluid viscosity - v fluid kinematic viscosity (/) - density - angular frequency (2/T) - - overbar, average - sub-c critical value     

Modeling study of a severe aerosol pollution event in December 2013over Shanghai China:An application of chemical data assimilation

This study focuses on the importance of initial conditions to air-quality predictions.We ran assimilation experiments using the WRF-Chem model and grid-point statistical interpolation(GSI),for a 9-day severe particulate matter pollution event that occurred in Shanghai in December 2013.In this application,GSI used a three-dimensional variational approach to assimilate ground-based PM2.5 observations into the chemical model,to obtain initial fields for the aerosol species.In our results,data assimilation significantly reduced the errors when compared to a simulation without assimilation,and improved forecasts of PM_(2.5)concentrations.Despite a drop in skill directly after the assimilation,a positive effect was present in forecasts for at least 12-24 h,and there was a slight improvement in the 48-h forecasts.In addition to performing well in Shanghai,the verification statistics for this assimilation experiment are encouraging for most of the surface stations in China.     

The influence of the wall thermal capacity and axial conduction over a single-phase natural circulation loop: 2-D numerical study

 In this paper the natural circulation phenomenon of a differentially heated single-phase natural circulation loop has been numerically investigated. The conservation equations of mass, momentum and energy are solved using a two-dimensional finite difference method. The preliminary results will be presented. The transient and steady-state behavior of the circuit has been investigated. The dependency of the temperature and velocity field on the power input and the wall thermal capacity has been analyzed, as well as the relationship between the most important non-dimensional numbers (Nusselt, Reynolds and the friction factor versus the modified Grashof number). A comparison of the numerical results is made with conventional one-dimensional analysis and with the experimental data. Generally, a good agreement is achieved in the stable region. Received on 17 January 2000     

International cooperation and networking in genetic health care provision: issues arising from the genetic services plan for the Emilia-Romagna region, Italy

The aims of this report are to describe the genetic plan for Emilia-Romagna, a region in Italy, and to contribute to the international exchange of information on developing and applying policy frameworks to provide high-quality and comprehensive genetic health care in the publicly funded health systems. At the present time there is no national policy for genetic medicine in Italy, and only two regions, Emilia-Romagna and Liguria, have formally agreed to a strategic plan for health care in genetics. The current provision of genetic services in Emilia-Romagna is described focusing on the intra- and inter-organizational linkages to ensure a comprehensive system of coordinated activities. Strengths and implementation areas are highlighted. Points that must be solved within the regional or national context are the definition of the level of assistance required in genetic medicine, the formal professional recognition of the genetic counselor and the adjustment of the billing mechanisms to the complexities of clinical genetic services. Issues that need to be addressed at a wider level include full assessment of genetic tests before their introduction into clinical practice, networking to provide tests for the rarest genetic diseases, consensus on fundamental terminology and clinical and administrative data sets to promote a cohesive framework for the flow of information throughout the health care systems with respect to genetics.     

Attrition resistance,a sporadically studied factor in aqueous adsorption: Status quo and research outlook towards creating better adsorbents

Attrition resistance in an adsorbent is one measure of its mechanical strength. It quantifies its ability to resist the impact of frictional forces generated in a milieu where hydrodynamic agitation exists. However, attrition resistance has been only sporadically examined in adsorbents used to remove aqueous adsorbates. Since attrition is relevant in aqueous adsorption process design, this review discusses the quantification of attrition resistance, variability in loss due to attrition across adsorbents, and the implications of attrition on adsorption systems. Finally, some key research opportunities that could be explored for a better understanding of attrition in real-scale water purification are presented. It is inferred that substantial research and development still needs to be accomplished to better understand the attrition resistance-adsorbent behavior within real-scale aqueous adsorption environments. The results can be harnessed to design and produce more robust, efficient and cost-effective adsorbents.