The Cawthron Institute Culture Collection of Micro-algae: a significant national collection

The Cawthron Institute Culture Collection of Micro-algae (CICCM) is a unique, nationally and internationally significant collection of 450 strains of approximately 100 micro-algae and 50 cyanobacteria species, both living and cryopreserved. The collection comprises 13 taxonomic classes and underpins research into the ecology and taxonomy of the isolates and the biotoxins they produce and their toxicity. The CICCM expanded significantly in the 1990s after a major harmful algae bloom event in the Hauraki Gulf, New Zealand. Since 2000, it has underpinned development of molecular detection tools and enabled development of new chemical testing methods for biotoxins in seafood. The tropical collection allows research into potential issues for New Zealand as the oceans warm, for example, the risks of ciguatera fish poisoning and palytoxins in seafood. Research results generated from isolates in the cyanobacterial collection have assisted national risk management regarding drinking water and informed the development of the New Zealand guidelines for managing cyanobacteria in recreational fresh waters. The actual living and cryopreserved micro-algae and cyanobacteria collection (without infrastructure) has a current estimated value of NZ$1.6 million.     

巷道围岩状态的等效应力等效应变表述

在体积应变为零的条件下,根据巷道围岩属简单加载的特性得到围岩中同时关联三向应力 , , 和三向应变 , , 的,用等效应力 和等效应变 表示的对围岩加载-形变关系式。严格地论证了巷道围岩的弹性、硬化、软化和流动区的应力应变状态分别与围岩的等效应力-等效应变曲线各阶段的应力应变状态相对应。以等效应力、等效应变为中间变量可以简化围岩弹性分析,简捷地写出巷道围岩偏应力应变能的计算公式。等效剪应力 是围岩中的最大剪应力 ,等效剪应力单元受正应力和剪应力作用,但其上只有剪切应变,这突出了巷道围岩形变破坏是由于最大剪应力和偏应力应变能所致的实质。根据等效剪应力概念确定的滑移线,可适用于材料应变硬化和软化阶段,不要求刚塑性假定条件。     

2015—2020年中国土地利用变化遥感制图及时空特征分析

持续地开展国家尺度土地利用/覆盖变化遥感监测对于新时代国土空间规划和“美丽中国”蓝图绘制具有重要的科学价值。本文采用Landsat 8 OLI、GF-2等卫星遥感数据,融合遥感大数据云计算和专家知识辅助人机交互解译方法,研发了中国土地利用变化（2015—2020年）和2020年土地利用现状矢量数据（CLUD 2020）,建立了完整的30 a（20世纪80年代末—2020年）每隔5 a的30 m分辨率中国土地利用动态数据库。基于CLUD 2020数据,从全国和区域两个尺度揭示了2015—2020年中国土地利用变化的总体规律、区域分异和主要特征。研究表明：将遥感大数据云计算生成的30 m分辨率植被覆盖变化和地表类型变化检测信息融入到人机交互遥感解译方法,可有效地提高大范围土地利用变化遥感制图的效率和变化图斑辨识的准确性;精度评价表明,CLUD 2020一级类型制图的综合精度达95%。总体上,全国范围内国土空间开发强度与2010—2015年比较进入相对稳定状态。期间全国耕地面积仍保持减少态势,空间分异特征为耕地南减北增,东北松嫩平原及其与三江平原交界区大规模的旱地向水田转移,西北新疆南部开垦和北部退耕/撂荒并存;全国城乡建设用地持续增加,空间分异特征表现为由以往的沿海地区和超大、大城市集聚转向中西部地区的大中小城镇周边蔓延为主。全国范围的林草自然生态用地面积持续减少,但强度与2010—2015年比较有所下降;受气候变化的持续影响,青藏高原地区的河流湖泊等水域面积显著增加。以上土地利用变化格局与“十三五”期间国家高质量发展、生态文明建设宏观战略和气候变化的影响密切相关。     

Perseid meteor stream 1991 – 1993 from TV observations in Kiev

Some results of the double station television meteor observations provided in Kiev during the Perseid shower period in years 1991 – 1993 are presented. The dependence of the beginning hights of meteors on their initial velocities based on 57 best reduced double station meteors is constructed. Exceptionaly great beginning heights of meteors are discussed, as well as the exceptional case of a Perseid bolide.     

近10年新疆积雪面积时空变化研究

区域尺度积雪信息的时空监测对确定雪灾的影响范围及灾情等级划分具有重要意义。本文利用近10年的MODIS积雪产品,按月最大面积的规则合成;分析了新疆积雪覆盖面积的时空变化特征,结果表明:时间上,新疆积雪面积有减少的趋势。空间上,近10年新疆积雪季节内永久性积雪覆盖区域主要分布在阿勒泰山脉、天山北麓及沿昆仑山脉西南部。其中天山及阿尔泰山之间的河谷及盆地的草原积雪面积波动主导了新疆整体积雪总面积的波动。     

On the residuals in asteroid catalogs and a possible nongravitational effect

Based on numerical calculations of the evolution of asteroid orbits, we concluded in one of our previous papers that a nongravitational effect causing the spatial separation of asteroids with different albedos and with sizes of tens of kilometers could act in the Solar system. To find new arguments, we have analyzed the residuals in the catalogs of asteroid orbits for 1996 and 2006. The dependences pointing to the possibility of a nongravitational effect for orbits with larger residuals have been found to be more distinct than those for orbits with smaller residuals. This result may be considered as an indirect confirmation of the above nongravitational effect.     

Orbital structure of the Kuiper belt and its contribution in the near-Earth asteroid and meteor population

Numerical calculations are given to describe evolution of orbits of simulated and real Kuiper belt objects for large intervals of time. Gravitational perturbations caused by all major planets have been taken into account, and, when considering small particles, Poynting-Robertson nongravitational effect has also been incorporated. Large orbit scattering of the Kuiper belt objects regarding the semimajor axes and eccentricities is shown to be due to their evolution over millions of years. Relative contribution of great objects and meteor particles from the Kuiper belt into the near-Earth population is believed to be extremely small.     

Contribution of tundra lakes in western Siberia to the atmospheric methane budget

The emission of methane from tundra lakes in western Siberia is estimated on the basis of experimental data. According to these estimates, over the warm season, the methane flux from the surfaces of lakes to the atmosphere amounts to 0.5 KtCH₄ for Arctic tundra, 2.9 KtCH₄ for typical tundra, and 8.5 KtCH₄ for southern tundra. The short-term spring emission of methane as ice melts in tundra lakes of the region under consideration is determined with consideration for published estimates of the rate of generation of methane in northern-latitude lakes during the cold season. The contribution made by tundra lakes in western Siberia to the atmospheric methane budget is estimated at 20 KtCH₄/year.     

Search for giant pulses of radio pulsars at frequency 111 MHz with LPA radio telescope

We have used the unique low frequency sensitivity of the Large Phased Array(LPA) radio telescope of Pushchino Radio Astronomy Observatory to collect a dataset consisting of single pulse observations of second period pulsars in the Northern Hemisphere. During observation sessions in 2011–2017, we collected data on 71 pulsars at a frequency of 111 MHz using a digital pulsar receiver. We have discovered Giant Radio Pulses(GRPs) from pulsars B0301+09 and B1237+25, and confirmed earlier reported generation of anomalously strong(probable giant) pulses from B1133+16 in a statistically significant dataset. Data for these pulsars and from B0950+08 and B1112+50, earlier reported as pulsars generating GRPs, were analyzed to evaluate their behavior over long time intervals. It was found that the statistical criterion(power-law spectrum of GRP distribution of energy and peak flux density) seems not to be strict for pulsars with a low magnetic field at their light cylinder. Moreover, spectra of some of these pulsars demonstrate unstable behavior with time and have a complex multicomponent shape. In the dataset for B0950+08, we have detected the strongest GRP from a pulsar with a low magnetic field at its light cylinder ever reported, having a peak flux density as strong as 16.8 kJy.     

地震孕育、发生、发展动态过程的三维有限元数值模拟

为探讨用数值方法模拟地震孕育、发生、发展动态过程的途径,从线性流变体介质内制约质点运动的运动方程出发,导出了模拟地震孕育、发生、发展动态过程的三维有限元方程及程序。还给出了模拟进程中地震孕育、发生、发展过程的约束条件,使得可以用同一个程序完整地模拟地震孕育、发生、发展的全过程,为地震过程本质的认识以及物理预报的实现提供了一个潜在的新手段。