医师资格考试多选题错同率检测软件的研究

对医师资格综合笔试多选题作弊雷同判断标准开展研究,通过错同率软件的设计,将错同率作为多选题作弊雷同检测指标,使两张试卷的错同率经过计算机比对,达到一定比例就可以认定为雷同试卷。

以错同率作为医师资格考试多选题作弊检测指标及意义的研究

在以错同率作为医师资格考试多选题作弊检测指标软件及影响因素研究的基础上,对以错同率作为医师资格综合笔试多选题作弊雷同判断标准开展研究,得出的结论是:医师资格综合笔试五选项选择题的平均错同率随着年份会有变化,但是错同率的上限浮动在0.5上下。当两个考生有客观作弊嫌疑,同时双向错同率在统计学意义上显著高于正常考场平均水平,作弊行为成立。

医师资格考试多选题错同率检测的影响因素研究

对医师资格综合笔试多选题作弊雷同判断标准开展研究,通过使用已设计的错同率软件,对错同率的影响因素进行研究。这对于无直接证据下的多选题作弊判定具有参考和应用价值,并可以起警戒提示作用,提高考试诚信震慑力,并更好实现资格考试的公平公正性。

k系列指数、g_2、错同率的抄袭识别效能比较研究

采用蒙特卡洛模拟的方法进行k系列指数、g2、错同率的抄袭识别效能比较实验,探讨影响五种抄袭统计量抄袭识别效能的因素。结果表明:(1)在被试样本量、项目数、被抄者的能力水平、抄袭率四个因素中,抄袭率对抄袭识别效能的影响最大,被抄者的能力水平、项目数次之,被试样本量的影响最小;(2)在上述因素相当的情况下,g2的抄袭识别经验I型错误率远高于α水平,抄袭识别率也最高,k1、k2的经验I型错误率远低于α水平,抄袭识别率较高,错同率的经验I型错误率略高于α水平,抄袭识别率较低,k*'的经验I型错误率几乎均为0,抄袭识别率最低;(3)在被怀疑的被抄者已确定的情况下,k1、k2的抄袭识别效能最高,是较理想的抄袭统计量;(4)在同等条件下,当被怀疑的被抄者和抄袭者均未确定时,五种抄袭统计量的抄袭识别效能较被怀疑的被抄者已确定的情形均大幅下降;(5)在缺乏被怀疑者信息的情况下,需设定更为保守的指标临界值,以降低误判风险。

不同应变率加载下硅的高压相变行为

高压相变是凝聚态物理、地球与行星科学、材料科学等领域关注的核心问题之一,而加载应变率是相变动力学过程的重要影响因素。由于动态加载下物质相结构原位诊断技术的不足以及宽广加载应变率下物质高压相变系统实验研究的缺失,难以开展基于原子尺度物理机制的相变动力学过程建模和数值模拟研究。由于硅的高压相极其丰富,且拥有大量亚稳相,动力学因素在其高压相变过程中发挥着至关重要的作用,因此,硅是研究高压相变动力学的理想材料,对普适相变动力学过程的理论建模具有重要意义。以硅为例,介绍其在准静态、中等应变率和高应变率加载下的相变行为,探讨加载应变率对其高压相变行为的影响。

四选项多选题作弊雷同的判定标准研究

在研究五选项多选题作弊雷同判定标准的基础上 ,本文以医学博士生英语入学考试为例 ,探讨了四选项多选题作弊雷同的判断标准问题。研究结果与五选项研究基本一致 :错同率在不同分数段具有一定稳定性 ,且接近选项的随机选择率。本研究建议当 2个考生的双向错同率在统计学意义上显著高于正常考场平均水平时 ,考试机构可以认定其存在作弊行为。研究结果对于无直接证据下的多选题作弊判定具有一定参考和应用价值。

透视高考“师范热”

近三年来，填报师范专业的考生越来越多，师范院校不仅生源充足，而且生源质量也逐渐提高。师范院校门前已经由过去的“门可罗雀”变成了现在的“门庭若市”。经过调查分析，我们可以清晰地看见这条“师范升温线”：据１９９５年８月２１日《中国教育报》报道，湖南全省该...

Effect of WS_2 addition on electrical sliding wear behaviors of Cu-graphite-WS_2 composites

Four kinds of Cu-based composites with different mass ratios of graphite and WS2 as lubricants were fabricated by hot-pressing method. Electrical sliding wear behaviors of the composites were investigated using a block-on-ring tribometer rubbing against Cu-5%Ag alloy ring. The results demonstrated that 800 ~C was the optimum sintering temperature for Cu-graphite-WS2 dual-lubricant composites to obtain the best comprehensive properties of mechanical strength and lubrication performance. Contact voltage drops of the Cu-based composites increased with increasing the mass ratio of WS2 to graphite. The Cu-based composite with 20% graphite and 10% WS2 showed the best wear resistance due to the excellent synergetic lubricating effect of graphite and WS2. The reasonable addition of WS2 into the Cu-graphite composite can remarkably improve the wear resistance without much rise of electrical energy loss which provides a novel principle of designing suitable sliding electrical contact materials for industrial applications.

Simulating leaf net CO_2 assimilation rate of C_3 & C_4 plants and its response to environmental factors

Basic structure and algorithm of leaf mechanism photosynthesis model were described in first part of this study based on former researcher results. Then, considering some environmental factors influencing on leaf photosynthesis, three numerical sensitivity experiments were carried out. We simulated the sing le leaf net CO2 assimilation, which acts as a function of different light, carbo n dioxide and temperature conditions. The relationships between leaf net photosy nthetic rate of C3 and C4 plant with CO2 concentration intercellular, leaf tempe rature, and photosynthetic active radiation (PAR) were presented, respectively. The results show the numerical experiment may indicate the main characteristic o f plant photosynthesis in C3 and C4 plant, and further can be used to integrate with the regional climate model and act as land surface process scheme, and bett er understand the interaction between vegetation and atmosphere.

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Simulating leaf net CO2 assimilation rate of C3 & C4 plants and its response to environmental factors

Basic structure and algorithm of leaf mechanism photosynthesis model were described in first part of this study based on former researcher results. Then, considering some environmental factors influencing on leaf photosynthesis, three numerical sensitivity experiments were carried out. We simulated the sing le leaf net CO2 assimilation, which acts as a function of different light, carbo n dioxide and temperature conditions. The relationships between leaf net photosy nthetic rate of C3 and C4 plant with CO2 concentration intercellular, leaf tempe rature, and photosynthetic active radiation (PAR) were presented, respectively. The results show the numerical experiment may indicate the main characteristic o f plant photosynthesis in C3 and C4 plant, and further can be used to integrate with the regional climate model and act as land surface process scheme, and bett er understand the interaction between vegetation and atmosphere.

A stabilized least-squares imaging condition with structure constraints

Conventional shot-gather migration uses a cross-correlation imaging condition proposed by Clarebout （1971）, which cannot preserve imaging amplitudes. The deconvolution imaging condition can improve the imaging amplitude and compensate for illumination. However, the deconvolution imaging condition introduces instability issues. The least-squares imaging condition first computes the sum of the cross-correlation of the forward and backward wavefields over all frequencies and sources, and then divides the result by the total energy of the forward wavefield. Therefore, the least-squares imaging condition is more stable than the classic imaging condition. However, the least-squares imaging condition cannot provide accurate results in areas where the illumination is very poor and unbalanced. To stabilize the least-squares imaging condition and balance the imaging amplitude, we propose a novel imaging condition with structure constraints that is based on the least-squares imaging condition. Our novel imaging condition uses a plane wave construction that constrains the imaging result to be smooth along geological structure boundaries in the inversion frame. The proposed imaging condition improves the stability of the imaging condition and balances the imaging amplitude. The proposed condition is applied to two examples, the horizontal layered model and the Sigsbee 2A model. These tests show that, in comparison to the damped least-squares imaging condition, the stabilized least-squares imaging condition with structure constraints improves illumination stability and balance, makes events more consecutive, adjusts the amplitude of the depth layers where the illumination is poor and unbalanced, suppresses imaging artifacts, and is conducive to amplitude preserving imaging of deep layers.

Reconsidering Melt-water Pulses 1A and 1B: Global Impacts of Rapid Sea-level Rise

Re-evaluation of the post-glacial sea level derived from the Barbados coral-reef borings suggests slightly revised depth ranges and timing of melt-water pulses MWP-1A (96-76 m, 14.3-14.0 ka cal BP) and 1B (58-45 m, 11.5-11.2 ka cal BP), respectively. Ages of non-reef sea-level indicators from the Sunda Shelf, the East China Sea and Yellow Sea for these two intervals are unreliable because of the well-documented radiocarbon ( 14C) plateau, but their vertical clustering corresponds closely with MWP-1A and 1B depth ranges. Close correlation of the revised sea-level curve with Greenland ice-core data suggests that the 14C plateau may be related to oceanographic-atmospheric changes due to rapid sea-level rise, fresh-water input, and impaired ocean circulation. MWP-1A appears to have occurred at the end of Blling Warm Transition, suggesting that the rapid sea-level rise may have resulted from lateral heat transport from low to high-latitude regions and subsequent abrupt ice-sheet collapses in both North America-Europe and Antarctica. An around 70 mm a -1 transgression during MWP-1A may have increased freshwater discharge to the North Atlantic by as much as an order of magnitude, thereby disturbing thermohaline circulation and initiating the Older Dryas global cooling.

Sand-Dust Storm Ensemble Forecast Model Based on Rough Set

To improve the accuracy of sand-dust storm forecast system, a sand-dust storm ensemble forecast model based on rough set (RS) is proposed. The feature data are extracted from the historical data sets using the self-organization map (SOM) clustering network and single fields forecast to form the feature values with low dimensions. Then, the unwanted attributes are reduced according to RS to discretize the continuous feature values. Lastly, the minimum decision rules are constructed according to the remainder attributes, namely sand-dust storm ensemble forecast model based on RS is constructed. Results comparison between the proposed model and the back propagation neural network model show that the sand-storm forecast model based on RS has better stability, faster running speed, and its forecasting accuracy ratio is increased from 17.1% to 86.21%.

Quality improvement of the dual-wavelength signals in DLOB via power equalization

The data packet buffeting can be implemented in dual loop optical buffer （DLOB） through cross-phase modulation （XPM） between the control signal and the data packets. However, the output equality of dual wavelength signals will degrade due to the unbalanced gain and phase shift. This problem can be resolved by power oqualizafion using the saturation characteristics of SOA. The data packets with 2.5 Gb/s can be buffered in DLOB for 16 cycles corresponding to 16.5 μs.The extinction ratio of the output packet is 8 dB while the S/N is 8.1 dB.

Results of mass endoscopic examination for gastric cancer in Kamigoto Hospital,Nagasaki Prefecture

AIM:To examine how the introduction of endoscopy to gastric cancer screening affected survival prognosis in a regional population. METHODS: The subjects comprised 4261 residents of Kamigoto,Nagasaki Prefecture,who underwent gastric X-ray examination for gastric cancer screening from 1991 to 1995,and all 7178 residents who underwent endoscopic examination for the same purpose from 1996 to 2003. The analysis evaluated trends in age-adjusted gastric cancer mortality rates and standard mortality ratios (SMRs) among the Kamigoto residents. RESULTS: According to demographic statistics,the 1995 and 2000 age-adjusted gastric cancer mortality rates in Nagasaki Prefecture (per 100 000 population) were 42.6 and 37.3 for males and 18.6 and 16.0 for females,while the corresponding rates in Kamigoto before and after the introduction of endoscopic screening were respectively 51.9 and 28.0,and 26.6 and 6.9. The data obtained in this study were divided into those for two periods,1990-1996 and 1997-2006,and SMRs were calculated separately for males and females. For the first period,the SMR was 1.04 (95% CI 0.50-1.58) for males and 1.54 (95% CI 0.71-2.38) for females,while for the second period the SMR was 0.71 (95% CI 0.33-1.10) for males and 0.62 (95% CI 0.19-1.05) for females. CONCLUSION: Following the introduction of endoscopic examination,gastric cancer death rates decreased in Kamigoto.

Performance of HT-PEMFC Based on Improved Baffle Structure

This study combines the three-dimensional model of the high-temperature proton exchange membrane fuel cell(HT-PEMFC)with theoretical analysis,by optimizing the structure of the fuel cell,adding a semicircular baffle in the gas channel and implementing novelly arranged obstacles to improve the PEMFC performance. The effects of velocity distribution,interface reactant concentration and pressure drop on performance are studied. The results show that adding obstacles in the gas channel will produce vertical velocity and can improve output performance,especially in the case of high current density and higher baffle radius. The superiority of the optimized structure in mass transfer capacity is proved,and a mechanism explanation is given for the improvement of performance.

Joint Timing and Frequency Synchronization for OFDM based on Fractional Fourier Transform

In this paper a joint timing and frequency synchronization method based on Fractional Fourier Transform （FIFT） is proposed for Orthogonal Frequency-Division Multiplexing （OFDM） system. The combination of two chirp signals with opposite chirp rates are used as the training signal, the received training signal with timing and frequency offset is transformed by FrFT and the two peaks representing two chirps in FrFT domain are detected, then the position coordinates of the two peaks are precisely corrected and substituted into an equation group to calculate timing and frequency offset simultaneously. This method only needs one FrFT calculation to implement synchronization, the computational complexity is equal to that of FFT and less than that of correlation or maximum likelihood calculation of existing methods, and estimation range of frequency offset is Large, greater than half the signal bandwidth, while the simulation results show that even at low SNR it can accurately estimate timing and frequency offset and the estimation error is less than that of existing methods.

DIFFERENCES AMONG DIFFERENT DATABASES IN THE NUMBER OF TROPICAL CYCLONES FORMING OVER THE WESTERN NORTH PACIFIC

As shown in comparisons of the characteristics of inter-annual and inter-decadal variability and periodical changes in the number of tropical cyclones forming over the western North Pacific by three major forecast centers, i.e. China Meteorological Administration (CMA), Regional Specialized Meteorological Center of Tokyo (JMA) and Joint Typhoon Warning Center (JTWC) of Guam, there are the following important points. (1) Climatology of tropical cyclone (TC) or typhoon (TC on the intensity of TS or stronger) shows some difference in tropical cyclone frequency among the centers, which is more notable with TC than with typhoon. Both of them are more at the database of CMA than at those of the other two centers. (2) The difference is too significant to ignore in the inter-annual variability of tropical cyclone frequency between CMA and JTWC, which mainly results from the obvious difference in the inter-annual variability of the number of generated tropical depression (TD) between the two databases. The difference is small in the inter-annual variability of TS formations among all the three databases, and consistence is good between JMA and CMA or JTWC. (3) Though differences are not significant in the periodical variation of TC formations between CMA and JTWC, they are markedly apart in the inter-decadal variability, which is mainly shown by an anti-phase during the 1990s. (4) Non-homogeneity may exist around the late stage of the 1960s in the data of tropical cyclone frequency.

Quantification of photosynthetic inorganic carbon utilisation via a bidirectional stable carbon isotope tracer

The amount of bicarbonate utilised by plants is usually ignored because of limited measurement methods. Accordingly, this study quantified the photosynthetic assimilation of inorganic carbon （COe and HCO3-） by plants. The net photosynthetic COa assimilation （PN）, the photosynthetic assimilation of CO2 and bicarbonate （PN＇）, the proportion of increased leaf area （lEA） and the stable carbon isotope composition （δ13C） of Orychophragmus violaceus （Ov） and Brassica juncea （B j） under three bicarbonate levels （5, 10 and 15 mm NaHCO3） were examined to determine the relationship among PN, PN＇ and fLA. PN＇, not PN, changed synchronously with fLA. Moreover, the proportions of exogenous bicarbonate and total bicarbonate （including exogenous bicarbonate and dissolved CO2-generated bicarbonate） utilised by Ov were 2.27 % and 5.28 % at 5 mm bicarbonate, 7.06 % and 13.28 % at 10 mm bicarbonate, and 8.55 % and 17.31% at 15 mm bicarbonate, respectively. Meanwhile, the propor- tions of exogenous bicarbonate and total bicarbonate uti- lised by Bj were 1.77 % and 3.28 % at 5 mm bicarbonate, 2.11% and 3.10 % at 10 mm bicarbonate, and 2.36 % and 3.09 % at 15 mm bicarbonate, respectively. Therefore, the dissolved CO2-generated bicarbonate and exogenous bicarbonate are important sources of inorganic carbon for plants.