Leaky Wave Antenna Based on Periodically Truncated SSPP Waveguide

Plasmonics - The guided waveguide structures based on surface plasmons can be used to miniaturize microwave devices. By simply introducing a series of periodic truncation slits in the SSPP (spoof...     

Sea State Adaptation Enhances Power Output of Triboelectric Nanogenerators for Tailored Ocean Wave Energy Harvesting

To face the climate crisis, sustainable energy harvesting systems are critical. Triboelectric nanogenerators (TENGs) are in the spotlight for their inexpensive and non-toxic manufacturing, allied with their excellence in harvesting low frequency vibrations. Ocean waves are a prime example of energy source in this regime, and their successful harvesting with TENGs has been widely demonstrated. However, the influence of wave characteristics on the power output of these devices has so far been overlooked. Here, the existence of a moving element that acts upon the nanogenerators is explored both with multiphysics simulations and an extensive experimental characterization under different operating conditions. It is shown how different sea states modulate the moving body velocity, and how the generator can be optimized to harvest waves with specific characteristics. In parallel, it is demonstrated that the power output is proportional to the contacting triboelectric layers velocity. Optimizing the dynamics of the moving body provides an efficient path to intentionally tune the contacting triboelectric layers velocity, and therefore improve the output of TENGs and their suitability to harvest specific sea states.     

基于联合锋电位-局部场电位的整合野调制特性研究

整合野调制在生物视觉系统的图形背景分离和轮廓检测中具有重要作用。为了研究整合野空间频率调制特性,首先测定单个神经元的感受野范围和整合类型,挑选出要研究的抑制性神经元;然后,用匹配追踪算法和希尔伯特变换提取Spike触发的伽马频带LFP瞬时能量;最后,将Spike触发的伽马频带LFP(local field potential,LFP)瞬时能量用于分析神经元的整合调制特性.对在大鼠初级视觉皮层(primary visual cortex,V1区)采集的96个神经元进行统计分析,实验结果表明:1)Spike触发的伽马频带LFP瞬时能量可以作为分析V1区整合野调制特性的有效指标;2)基于Spike触发的伽马频带LFP瞬时能量所获得的抑制指数要显著高于通过Spike发放率以及伽马频带LFP功率的结果(P0.001),并且整合野的调制规律性更加明显,个体适用性更好。     

高强度聚焦超声换能器温度场的数值仿真

相控阵高强度聚焦超声换能器可以通过换能器上不同阵元发射超声波的时间不同来实现变焦、多焦点。该论文应用Westervelt方程的近似式,结合Pennes热传导方程,以人体乳房为例,FDTD(finite difference time domain)仿真对比研究平面阵列相控聚焦换能器与曲面阵列相控聚焦换能器形成温度场的特性,同时数值仿真研究不同占空比的正弦激励函数、不同治疗频率、声强对曲面阵列相控聚焦换能器超声温度场的影响。研究结果表明曲面阵列相控聚焦换能器能有效地减少皮肤处的温升,对皮肤的伤害较小;对于曲面阵列相控聚焦换能器,不同占空比的正弦激励函数形成的可治疗区域(60℃以上)大小差别不大,但最高温度不同;随着频率升高,形成的可治疗区域体积减小;随着输入声强的增大,可治疗区域变大,但焦距不变。     

Quantification of the Field Enhancement of Surface Plasmon Under Standing Wave Conditions

Plasmonics - We performed a quantitative study of the field intensity under surface plasmon (SP) using different impinging source changing the beam width for several metallic structures and compare...     

Iron Limitation Modulates Ocean Acidification Effects on Southern Ocean Phytoplankton Communities

The potential interactive effects of iron (Fe) limitation and Ocean Acidification in the Southern Ocean (SO) are largely unknown. Here we present results of a long-term incubation experiment investigating the combined effects of CO₂ and Fe availability on natural phytoplankton assemblages from the Weddell Sea, Antarctica. Active Chl a fluorescence measurements revealed that we successfully cultured phytoplankton under both Fe-depleted and Fe-enriched conditions. Fe treatments had significant effects on photosynthetic efficiency (F_v/F_m; 0.3 for Fe-depleted and 0.5 for Fe-enriched conditions), non-photochemical quenching (NPQ), and relative electron transport rates (rETR). pCO₂ treatments significantly affected NPQ and rETR, but had no effect on F_v/F_m. Under Fe limitation, increased pCO₂ had no influence on C fixation whereas under Fe enrichment, primary production increased with increasing pCO₂ levels. These CO₂-dependent changes in productivity under Fe-enriched conditions were accompanied by a pronounced taxonomic shift from weakly to heavily silicified diatoms (i.e. from Pseudo-nitzschia sp. to Fragilariopsis sp.). Under Fe-depleted conditions, this functional shift was absent and thinly silicified species dominated all pCO₂ treatments (Pseudo-nitzschia sp. and Synedropsis sp. for low and high pCO₂, respectively). Our results suggest that Ocean Acidification could increase primary productivity and the abundance of heavily silicified, fast sinking diatoms in Fe-enriched areas, both potentially leading to a stimulation of the biological pump. Over much of the SO, however, Fe limitation could restrict this possible CO₂ fertilization effect.     

基于计算机模拟的蛋白质分离纯化实验

利用数学建模的方法首次提出了衡量分离纯化效果优劣的定量指标——纯化效益;建立了便于应用推广的聚乙二醇(polyethyleneglycol,PEG)和硫酸铵沉淀分离纯化模型,并以海芋过氧化物酶分离纯化为例,对模型进行求解、应用和检验,求解最优实验试剂用量.     

Ornithopter Flight Simulation Based on Flexible Multi-Body Dynamics

This paper introduces a flight simulation of an ornithopter (flapping-wing air vehicle) based on the flexible multi-body dynamics, a refined flapping-wing aerodynamic model and the fluid-structure interaction approach. A simulated ornithopter was modeled using the multi-body dynamics software, MSC.ADAMS, where the flexible parts can be included by importing a finite element model built in the finite element analysis software, ANSYS. To model the complex aerodynamics of flapping-wing, an improved version of modified strip theory was chosen. The proposed integrative simulation framework of ornithopter was validated by the wind tunnel test data reported in the literature. A magpie-sized model oruithopter was numerically designed and simulated to have the longitudinal trim flight condition. We observed a limit-cycle-oscillation of flight state variables, such as pitch attitude, altitude, flight speed, during the trimmed flight of the model ornithopter. Under the trimmed condition of free flight of the model omithopter, we fixed all the degrees of freedom at the center of gravity to measure the constraint forces and moment. The concept of the "zero moment point" is introduced to explain the physics of ornithopter trimmed longitudinal flight.     

基于COXI基因的太平洋西岸文昌鱼地理种群分析

文昌鱼是进化发育研究的重要模式动物,目前实验材料均采自野外.因此,对其进行正确的物种鉴定和地理种群的遗传分化分析十分必要.该研究扩增并测定了COX 1基因部分序列,结合NCBI数据库中的COX 1序列信息,对太平洋西岸文昌鱼的种类和地理种群分化情况进行了分析.结果表明,马来文昌鱼(Branchiostoma malayanum)、白氏文昌鱼(B.belcheri)和日本文昌鱼(B.japonicum)这3个种之间的遗传差异很大,再次证实3个物种的有效性,同时提出应当审慎对待NCBI数据库中文昌鱼的种名标注;太平洋西岸文昌鱼属Branchiostoma的3种文昌鱼群体遗传多样性均处于较高水平,同一物种的不同地理种群间没有出现明显的遗传分化,反映了海洋动物的基因交流较容易,不同海域隔离较弱.     

来自海洋的危机报告

毫无疑问,鲨鱼是海上霸王。全世界的鲨鱼有30科、368种。鲨鱼的寿命一般为25岁,但有些鲨鱼可以活到100岁。鲸鲨是鲨鱼种类中体形最大的,也是海里最大的鱼类,身体直径比人还高,最大体长可达18米,体重40吨。最小的鲨鱼是侏儒鲨,最大只能长到11英寸。根据化石记录,鲨鱼发生于4亿年前,在至少经历过地球上四次生物大灭绝,其中80％地球上生物灭绝的情况下,鲨鱼劫后余生,本性不改。历经沧桑几亿年,好不容易存活下来的鲨鱼现在却由于其肝、鳍和骨头有益于人类而走向毁灭的厄运。     

Modeling Calcium Wave Based on Anomalous Subdiffusion of Calcium Sparks in Cardiac Myocytes

sparks and waves play important roles in calcium release and calcium propagation during the excitation-contraction (EC) coupling process in cardiac myocytes. Although the classical Fick’s law is widely used to model sparks and waves in cardiac myocytes, it fails to reasonably explain the full-width at half maximum(FWHM) paradox. However, the anomalous subdiffusion model successfully reproduces sparks of experimental results. In this paper, in the light of anomalous subdiffusion of sparks, we develop a mathematical model of calcium wave in cardiac myocytes by using stochastic release of release units (CRUs). Our model successfully reproduces calcium waves with physiological parameters. The results reveal how concentration waves propagate from an initial firing of one CRU at a corner or in the middle of considered region, answer how large in magnitude of an anomalous spark can induce a wave. With physiological currents (2pA) through CRUs, it is shown that an initial firing of four adjacent CRUs can form a wave. Furthermore, the phenomenon of calcium waves collision is also investigated.     

An Angle-Insensitive Metamaterial Absorber Based on the Gravity Field Regulation

Plasmonics - In this paper, we propose a novel gravity-tailored absorber to achieve two different absorption peaks at two different frequencies, whose improvement is based on the traditional...     

Brain and Heart: The Problem of the Wave Field of the Human Body

The results of studies of the effects of intense mental work on cardiac activity and circulation are reviewed. The problems of the information field are discussed. According to the concept put forward in this work, the wave radiation components emitted by the human brain, heart, and blood are the main constituents of the integral information field of the human body.     

基于远洋卫勤保障的护理人员培训知识体系构建

目的 构建一套满足我国远洋卫勤保障任务及需求的护理人员培训知识体系。方法 采用文献分析法、专家访谈法和德尔菲法建立指标体系,运用层次分析法确定各指标权重系数。结果 专家权威系数为0.835,形成包括4个一级指标、13个二级指标和56个三级指标的我国护理人员参与远洋卫勤保障任务的培训知识体系,各条目协调系数为0.296~0.423,差异比较有统计学意义（P＜0.05）。结论 专家意见集中,结果可信,可为参与远洋卫勤保障任务的护理人员培训、考核提供量化的参考依据。     

基于计算机模拟的介入器械放置及设计研究

心血管介入器械的使用越来越广泛，综合考虑血流、器械和血管的作用情况，研究器械的放置和设计问题，有助于减少器械诱发的并发症，提高其使用的效果。采用计算机建模，有限体积法生成网格，通过计算流场来分析器械使用前后流场改变的方法，说明了介入器械的结构和使用方式对血管有不同方面及程度的影响。对于研究其他的一些和血管接触的器械也有一定的参考价值。     

个体运动的病毒传播行为模拟

提出了一个基于二维规则网格的SIS(Susceptible-Infected-Susceptible)动态疾病传播模型,并用元胞自动机方法进行计算机模拟,考查该模型中感染概率、治愈概率、人群密度及人群的流动对疾病传播的影响,结果表明,系统的稳态感染比例随感染概率和人群密度的增加而增大,随治愈概率的增加而减小,同等条件下流动人群比静止人群更容易传播疾病,根据这些研究结论最后给出了对应的疾病预防和控制措施。     

Simulation of Lake Victoria Circulation Patterns Using the Regional Ocean Modeling System (ROMS)

Lake Victoria provides important ecosystem services including transport, water for domestic and industrial uses and fisheries to about 33 million inhabitants in three East African countries. The lake plays an important role in modulating regional climate. Its thermodynamics and hydrodynamics are also influenced by prevailing climatic and weather conditions on diel, seasonal and annual scales. However, information on water temperature and circulation in the lake is limited in space and time. We use a Regional Oceanographic Model System (ROMS) to simulate these processes from 1^st January 2000 to 31^st December 2014. The model is based on real bathymetry, river runoff and atmospheric forcing data using the bulk flux algorithm. Simulations show that the water column exhibits annual cycles of thermo-stratification (September–May) and mixing (June–August). Surface water currents take different patterns ranging from a lake-wide northward flow to gyres that vary in size and number. An under flow exists that leads to the formation of upwelling and downwelling regions. Current velocities are highest at the center of the lake and on the western inshore waters indicating enhanced water circulation in those areas. However, there is little exchange of water between the major gulfs (especially Nyanza) and the open lake, a factor that could be responsible for the different water quality reported in those regions. Findings of the present study enhance understanding of the physical processes (temperature and currents) that have an effect on diel, seasonal, and annual variations in stratification, vertical mixing, inshore—offshore exchanges and fluxes of nutrients that ultimately influence the biotic distribution and trophic structure. For instance information on areas/timing of upwelling and vertical mixing obtained from this study will help predict locations/seasons of high primary production and ultimately fisheries productivity in Lake Victoria.     

Thigmomorphogenesis: The Interaction of Wind and Temperature in the Field on the Growth of Phaseolus vulgaris L.

Field and laboratory experiments were performed to determinethe interaction of wind and temperature on thigmomorphogenesis(defined here as decreased elongation and increased internodalradial enlargement due to mechanical perturbation). Kidney beanplants (Phaseolus vulgaris L. cv. Red Cherokee Wax) were shelteredor exposed to wind for 10 days. Wind velocity, wind gusting,temperature, light and rainfall were measured for the durationof each of ten experiments. Stem elongation and diameter weremeasured and it was found that thigmomorphogenesis due to windoccurs naturally. There was more internodal secondary xylemproduced in the wind-exposed plants than in the sheltered plants.The experimental data were analyzed by multiple linear regressionand the wind was found to be a significant factor in the predictionof bean stem elongation and thickening. Laboratory experimentsshow that as wind velocity increases, thigmomorphogenesis increasesin an approximate linear fashion. Furthermore, it was foundthat low temperatures interact with mechanical perturbationto reduce the amount of thigmomorphogenesis, both in the fielddue to wind and in the laboratory due to rubbing. Other environmentalfactors do not seem to interact with the wind to modulate thigmomorphogenesiseven though these factors affect plant growth. Phaseolus vulgaris L., kidney bean, thigmomorphogenesis, wind, temperature, ethylene, multiple linear regression