宫颈癌放疗高危临床靶区变化及其对累计吸收剂量的影响

【摘要】目的：在宫颈癌放疗的全过程中，肿瘤的大小和位置都会改变。本研究观测高危临床靶区（HRCTV）在放疗期间变化程度，及这些变化对HRCTV累计吸收剂量的影响。方法：从我院2011年10月-2014年6月放疗结束的病人中任选22个病人，病人的体外放疗计划是基于放疗前的CT图像用VARIANECLIPSE制定，在CT图像上勾画出PTV。每个病人体外放疗共45Gy／25次。体外放疗两周后，开始体内放疗，每周1次，共4次28Gy。每次体内放疗前，基于病人的CT图像用NUCTRONONCENTRA制定内照射计划，在CT图像上勾画出HRCTV。每个病人有l组外照射计划CT图像和4组近距离治疗计划的CT图像。用ONCENTRA把近距离计划的CT图像导入ECLIPSE中，经过图像融合，观察测量4次体内放疗的HRCTV变化。观测外照射对每个HRCTV的D95变化。用HRCTV变形指数描述病人多次体内放疗之间HRCTV变化程度，用非PTV指数描述体外照射PTV不能完全覆盖体内放疗HRCTV的程度，用HRCTV相对于体外照射PTV剂量的相对剂量（RelativePTVDose，RPD）描述体外照射对HRCTV的累计剂量情况。结果：共计22个体外放疗计划和88个体内放疗计划被分析。HRCTV变形指数平均值为0．45±0．13，非PTV指数平均值为0．05±0．13，相对于体外照射PTV剂量的相对剂量为-0．02±0．13，RPD〉0共有50次，占56．8％（50／88），RPD=0共有8次，占9．1％（8／88），RPD〈0共有30次，占34．1％（30／88）。结论：宫颈癌每次体内放疗（时间间隔1周及以上）HRCTV变化较大，但基本都在外照射PTV内，HRCTV受到的累计体外照射剂量，大多数情况下不等于体外照射的处方剂量，在计算病人放疗累计剂量时，应针对每个病例具体分析。

Linear and Nonlinear Optical Properties in Spherical Quantum Dots

We calculate the energy eigenvalues and the sate functions of one-electron Quantum Dot （QD） by using a combination of Quantum Genetic Algorithm （QGA） and Hartre-Fock-Roothaan （HFR） method. The linear and the third-order nonlinear optical absorption coefficients for the 1s-1p, 1p-1d, and 1d-1f transitions are examined as a function of the incident photon energy for three different values of the stoichiometric ratio. The results show that the stoichiometric ratio, impurity, relaxation time, and dot size have great influence on the optical absorption coefficients of QDs.

Absorptive Capacity and Knowledge Flows for Large International Finns： A Survey

The main objective of this paper is that of surveying both theoretic and econometric models exploring the existence of knowledge spillovers and quantifying firm＇s ability to identify, assimilate, and exploit existing information （absorptive capacity）. In so doing, we explore different methodologies through which we may analyze the knowledge transmission： both the production function approach and the knowledge function approach. In order to construct the spillover stocks, different dimensions are considered： geographic and technological.

Study on Hysteretic Bond Mechanisms of Plain Round Bar

Plain round bars were commonly used as main bars in the design of RC （reinforced concrete） buildings prior to the 1970s. According to previous research investigating the seismic performance of reinforced concrete members constructed with plain round bars, the strength of those members did not reach the calculated flexural strength due to bond slippage of main bars before yielding. It is important, therefore, to investigate the hysteretic bond mechanisms of plain round bars in concrete. In this research, analytical models were proposed to predict hysteretic bond-slip mechanisms between plain round bar and concrete depending on the results of experiments performed by the authors. In addition, the energy absorption capacity and the equivalent viscous damping factors obtained from the experimental results and analytical models are discussed. As a result of comparisons between the experimental data and the analysis models, good agreements were obtained.

Uncertainty Estimation for the Determination of Trace Heavy Metals in Human Hair by Flame and Electrothermal Atomic Absorption Spectrometry

Trace element analysis on hair samples has been widely used to assess wildlife and human exposure to different contaminants present in the environment or at the workplace. Pollutants due to the presence of toxic metals in environment not only enter the body by breading, water, and foodstuff accumulates in hair, but they could be adsorbed directly on the hair from environment. In order to remove adsorbed elements and thus determine the internally bound elements correctly, hair sample must be washed. In the present work, we propose uncertainty estimation for the analytical results that are obtained from determination of cadmium, lead, copper, iron, manganese and nickel in human hair by flame and electrothermal atomic absorption spectrometry （FAAS and ETAAS）. To estimate the uncertainty of analytical result obtained, two types of bias are calculated in the assessment of trueness： a proportional bias and a constant bias. Nested design was applied for calculating proportional bias and Youden method to calculate the constant bias. The results we obtained for proportional bias are calculated from spiked samples. In this case, the concentration found is plotted against the concentration added and the slop of standard addition curve is an estimate of the method recovery. Estimated method of average recovery in human hair is： （1.019 ±0.026）, （0.918 ±0.014）, （1.073±0.016）, （1.0597± 0.017）, （1.073± 0.020） and （0.934± 0.117） for Cd, Pb, Mn, Ni, Fe and Cu respectively.

Experimental investigation on solar-flue gas chimney

Flue gases exhausted from thermal power plants contain more than 50% of the fuel thermal energy. In the present work, experimental investigation was carried out to study the utilization of thermal energy in flue gases to enhance the performance of modified solar chimney consisting of Savonius wind rotor. A modified solar chimney model was designed and fabricated to carry out experimental measurement. The model consists of thermal energy conversion unit; Savonius wind rotor and a chimney. The thermal energy in the flue gas transfers to the air particles in the air channel across the absorber plate and results in upward air stream due to the buoyancy effect. With an 9 absorber area of 2.36 re＇and flue gas mass flow rate of0.18 kg/s, air velocity＇ of 4.1 m/s was achieved at the top of the thermal unit. Increasing the mass flow rate of the flue gas to 0.24 kg/s enhances the air velocity to be 4.6 m/s. The results have demonstrated the possibility＇ of utilizing the thermal energy in the waste flue gas to enhance the performance of a solar chimney and facilitate the continuous operation during the absence of the sun.

Nutrient resorption and stoichiometric responses of poplar(Populus deltoids)plantations to N addition in a coastal region of eastern China

Aims Leaf nutrient resorption is sensitive to changes in soil nutrients.However,the effects of N deposition on nutrient resorption efficiency(NuRE)in plant macro-nutrients remain unclear.Poplar(Populus deltoids)is one of the most extensively cultivated hardwood species worldwide.We explored general patterns and dominant drivers of NuRE and stoichiometry of poplar plantations in response to N addition.Methods We conducted a 4-year N-addition experiment to explore NuRE and stoichiometric responses to N addition in two poplar(P.deltoids)plantations(8-and 12-year-old stands)in a coastal region of eastern China.We measured soil and foliar(green and senesced leaves)concentrations of nitrogen(N),phosphorus(P),potassium(K),calcium(Ca)and magnesium(Mg)for a series of N addition treatments including N_(0)(0 kg N ha^(−1)yr^(−1)),N_(1)(50 kg N ha^(−1)yr^(−1)),N_(2)(100 kg N ha^(−1)yr^(−1)),N_(3)(150 kg N ha^(−1)yr^(−1))and N_(4)(300 kg N ha^(−1)yr^(−1)).Important Findings Consistent for(both)8-and 12-year-old stands,N addition did not affect the NuRE and stoichiometry(with the exception of CaRE and CaRE:MgRE ratio).N resorption efficiency–P resorption efficiency(NRE–PRE)scaling slopes were consistently less than 1.0 under N addition.These results suggest that NRE generally decouples from PRE within each N treatment.Moreover,these results point to robust control of green leaf nutritional status on nutrient resorption processes as indicated by the positive relationships between NuRE and green leaf nutrient concentrations.Our findings provided a direct evidence that growth in 12-year-old poplar plantations was N-limited in the coastal region of eastern China.

Compressive properties and energy absorption of BCC lattice structures with bio-inspired gradient design

Inspired by the gradient structure of the nature,two gradient lattice structures,i.e.,unidirectional gradient lattice(UGL)and bidirectional gradient lattice(BGL),are proposed based on the body-centered cubic(BCC)lattice to obtain specially designed mechanical behaviors,such as load-bearing and energy absorption capacities.First,a theoretical model is proposed to predict the initial stiffness of the gradient lattice structure under compressive loading,and validated against quasi-static compression tests and finite element models(FEMs).The deformation and failure mechanisms of the two structures are further studied based on experiments and simulations.The UGL structure exhibits a layer-by-layer failure mode,which avoids structure-wise shear failure in uniform structures.The BGL structure presents a symmetry deformation pattern,and the failure initiates at the weakest part.Finally,the energy absorption behaviors are also discussed.This study demonstrates the potential application of gradient lattice structures in load-transfer-path modification and energy absorption by topology design.