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3.
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. 相似文献
5.
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. 相似文献
8.
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. 相似文献
9.
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. 相似文献
10.
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. 相似文献
11.
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 相似文献
12.
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 相似文献
13.
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. 相似文献
14.
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. 相似文献
15.
Three kinds of grid system based on C-type grid are examined in order to reveal their relative flow characteristics of the turbomachinery cascade, especially near the trailing edge and wake. Here, a semi-conservative interpolation technique to treat the discontinuous boundary condition along the periodic boundary is proposed and is applied on the patched-type grid structure. Computational results are presented to see the influence of trailing-edge grid structure on the Navier-Stokes solutions for the high-turning transonic turbine cascade. 相似文献
18.
An experimental study of a system that is parametrically excited through a bifurcation parameter is presented. The system consits of a lightly-damped, flexible beam which is buckled and unbuckled magnetically: it is parametrically excited by driving an electromagnet with a low-frequency sine wave. For voltage amplitudes in excess of the static bifurcation value, the beam slowly switches between the one-and two-well configurations. Experimental static and dynamic bifurcation results are presented. Static bifurcatons for the system are shown to involve a butterfly catastrophe. The dynamic bifurcation diagram, obtained with an automated data acquisition system, shows several period-doubling sequences, jump phenomena, and a chaotic region. Poincaré sections of a chaotic steady-state are obtained for various values of the driving phase, and the correlation dimension of the chaotic attractor is estimated over a large scaling region. Singular system analysis is used to demonstrate the effect of delay time on the noise level in delay-reconstructions, and to provide an independent check on the dimension estimate by directly estimating the number of independent coordinates from time series data. The correlation dimension is also estimated using the delay-reconstructed data and shown to be in good agrement with the value obtained from the Poincaré sections. The bifurcation and dimension results are used together with physical sonsiderations to derive the general form of a single-degree-of-freedom model for the experimental system. 相似文献
19.
Flow over a rectangular porous block placed in a fixed width channel is considered and the influence of block aspect ratio on the heat transfer rate from the block is examined. A non-porous solid block is also accommodated to compare the effect of porosity on the flow field and heat transfer characteristics. Aspect ratio and the porosity of the block are varied in the simulations. A numerical scheme employing a control volume approach is considered when predicting the flow and temperature fields. The Reynolds number is selected to yield the mix convection situation in the flow field. It is found that the aspect ratio significantly influences Nu and Gr numbers, in which case increasing the aspect ratio enhances Nu while lowering Gr. Increasing porosity improves the heat transfer rates from the porous block, provided that at high aspect ratios, this situation ceases due to blockage effect of the body in the channel. 相似文献
20.
OBJECTIVE: To determine the personal characteristics and reasons associated with providing a buccal swab for apolipoprotein E (APOE) genetic testing in a primary care study. METHODS: The study sample consisted of 342 adults aged 65 years and older recruited from primary care settings. RESULTS: In all, 88% of patients agreed to provide a DNA sample for APOE genotyping and 78% of persons providing a sample agreed to banking of the DNA. Persons aged 80 years and older and African-Americans were less likely to participate in APOE genotyping. Concern about confidentiality was the most common reason for not wanting to provide a DNA sample or to have DNA banked. CONCLUSION: We found stronger relationships between sociodemographic variables of age and ethnicity with participation in genetic testing than we did between level of educational attainment, gender, function, cognition, and affect. 相似文献
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