美国高校计算机基础教学的启示

研究总结了美国高校计算机基础教学与我国相比的差异,分析其教学特点,如教学内容注重应用、使用有利于培养应用型人才的嵌入式的教学模式、以展开实例的方式教学组织形式等,借鉴美国高校计算机基础教学的经验以促进我国高校计算机基础教学的发展。     

引进美国甘蔗种质工艺品质演进分析及发掘

本研究主要基于投影寻踪分类法（PPC）对引进美国甘蔗种质主要工艺品质性状进行世代演进和种质评价分析。根据育成或改良年代（10~20 a为时间界点）把引进的58份美国甘蔗种质划分4个改良世代,基于大田试验,对甘蔗锤度、甘蔗蔗糖分、蔗汁蔗糖分、甘蔗纤维分、甘蔗简纯度等5个重要工艺品质性状指标进行方差、投影寻踪分类和聚类分析,以揭示其世代演进特征和筛选工艺品质优异种质资源用于杂交育种。方差分析表明,世代内和世代间各种质资源工艺品质性状存在显著差异（P<0.05）,变异系数在2%~20%之间,其中甘蔗蔗糖分、蔗汁蔗糖分和简纯度3个品质性状还存在世代和月份间的显著交互作用。投影寻踪分类法评价分析表明,不同世代美国甘蔗种质资源投影值差异显著,其中以第1代最低,依次增加,第4代最高;投影方向以甘蔗蔗糖分最高,依次为蔗汁蔗糖分和甘蔗锤度,简纯度和纤维分最低。根据投影值大小的聚类分析表明,58份种质可以划分为4类。筛选了主要工艺品质性状优良的甘蔗种质18份（第Ⅱ类）用于杂交育种,其中来自第4代的材料有6份,占第4代材料总数的46.15%;来自第3代的材料有10份,占总数的37.07%;来自第2代的材料有1份,占总数18.18%;第一代材料未筛选出品质优良种质资源。以上结果可以看出,美国甘蔗种质资源主要工艺品质改良显著,随着世代演进而显著提升。表现优异外引种质以第4代所占比重最高,依次递减,第一代最少,优异种质多来源于演进次数最多的世代;投影寻踪分类法可作为甘蔗改良效果和种质资源评价研究的另一途径。     

Change in avian abundance predicted from regional forest inventory data

An inability to predict population response to future habitat projections is a shortcoming in bird conservation planning. We sought to predict avian response to projections of future forest conditions that were developed from nationwide forest surveys within the Forest Inventory and Analysis (FIA) program. To accomplish this, we evaluated the historical relationship between silvicolous bird populations and FIA-derived forest conditions within 25 ecoregions that comprise the southeastern United States. We aggregated forest area by forest ownership, forest type, and tree size-class categories in county-based ecoregions for 5 time periods spanning 1963–2008. We assessed the relationship of forest data with contemporaneous indices of abundance for 24 silvicolous bird species that were obtained from Breeding Bird Surveys. Relationships between bird abundance and forest inventory data for 18 species were deemed sufficient as predictive models. We used these empirically derived relationships between regional forest conditions and bird populations to predict relative changes in abundance of these species within ecoregions that are anticipated to coincide with projected changes in forest variables through 2040. Predicted abundances of these 18 species are expected to remain relatively stable in over a quarter (27%) of the ecoregions. However, change in forest area and redistribution of forest types will likely result in changed abundance of some species within many ecosystems. For example, abundances of 11 species, including pine warbler (Dendroica pinus), brown-headed nuthatch (Sitta pusilla), and chuck-wills-widow (Caprimulgus carolinensis), are projected to increase within more ecoregions than ecoregions where they will decrease. For 6 other species, such as blue-winged warbler (Vermivora pinus), Carolina wren (Thryothorus ludovicianus), and indigo bunting (Passerina cyanea), we projected abundances will decrease within more ecoregions than ecoregions where they will increase.     

Model estimates of net primary productivity,evapotranspiration, and water use efficiency in the terrestrial ecosystems of the southern United States during 1895–2007

The effects of global change on ecosystem productivity and water resources in the southern United States (SUS), a traditionally ‘water-rich’ region and the ‘timber basket’ of the country, are not well quantified. We carried out several simulation experiments to quantify ecosystem net primary productivity (NPP), evapotranspiration (ET) and water use efficiency (WUE) (i.e., NPP/ET) in the SUS by employing an integrated process-based ecosystem model (Dynamic Land Ecosystem Model, DLEM). The results indicated that the average ET in the SUS was 710 mm during 1895–2007. As a whole, the annual ET increased and decreased slightly during the first and second half of the study period, respectively. The mean regional total NPP was 1.18 Pg C/yr (525.2 g C/m²/yr) during 1895–2007. NPP increased consistently from 1895 to 2007 with a rate of 2.5 Tg C/yr or 1.10 g C/m²/yr, representing a 27% increase. The average WUE was about 0.71 g C/kg H₂O and increased about 25% from 1895 to 2007. The rather stable ET might explain the resulting increase in WUE. The average WUE of different biomes followed an order of: forest (0.93 g C/kg H₂O) > wetland (0.75 g C/kg H₂O) > grassland (0.58 g C/kg H₂O) > cropland (0.54 g C/kg H₂O) > shrubland (0.45 g C/kg H₂O). WUE of cropland increased the fastest (by 30%), followed by shrubland (17%) and grassland (9%), while WUE of forest and wetland changed little from the period of 1895–1950 to the period of 1951–2007. NPP, ET and WUE showed substantial inter-annual and spatial variability, which was induced by the non-uniform distribution patterns and change rates of environmental factors across the SUS. We concluded that an accurate projection of the regional impact of climate change on carbon and water resources must consider the spatial variability of ecosystem water use efficiency across biomes as well as the interactions among all stresses, especially land-use and land-cover change and climate.     

美国高等林业教育概览——以纽约州立大学环境科学与林业科学学院为例

首先介绍美国高等林业教育和纽约州立大学环境科学与林业科学学院(SUNY-ESF)的概况;进而分析SUNY-ESF的管理运作体系,专业、课程及学位设置状况,学院师资引进、晋升、评审和考核状况,学生的学习和生活事务状况;最后总结了几点可供借鉴的经验:民主的分权管理模式,科学的专业、课程和学位设置体系,突出的师资队伍建设水平,人性化的学生事务服务理念。     

美国丹佛樱桃溪生态廊道人工修复成功案例

文章根据笔者在美国丹佛市考察期间的部分见闻整理而成,通过现场观察和资料收集,对丹佛樱桃溪生态廊道人工修复工程项目做了全面介绍,其中社会参与、财务公开、科普宣传及坡面治理等经验值得我国借鉴。       

Fuelling the fisheries subsidy debate: Agreements, loopholes and implications

There is a general consensus that most subsidies to fisheries, particularly fuel subsidies, are harmful to both the economy and the environment. As the World Trade Organization struggles to come to an agreement on fisheries subsidies, understanding the position of the negotiating countries is crucial. As we move toward more sustainable regulations, we must ensure that no loopholes exist for countries to evade binding regulations. In this note, we use the example of the United States to illustrate how arguments for exemptions can lead to such loopholes. The United States provides interesting insight, as it appears that their support for a ban on fisheries subsidies may be contingent upon a legal pun, which would allow them and other countries to carry on subsidizing fuel to their fishing fleets into the future.     

An appraisal of Miscanthus x giganteus cultivation for fly ash revegetation and soil restoration

The objective of this study was to investigate the potential of Miscanthus x giganteus (MxG) for fly ash (FA) revegetation and soil restoration. To evaluate its growth ability on FA, plant development during pot experiments was compared to that obtain in a reference soil. Several physico-chemical parameters (pH, conductivity, dissolved organic carbon, ammonium, nitrite, nitrate, phosphate and potassium contents) and microbiological parameters (enumeration of total, ammonia oxidising and nitrite oxidising culturable bacteria and community diversity analysis) were investigated after plant growth. Plants demonstrated an adaptation to the FA substrate, with an average stem length and biomass production that was half of that observed in the reference soil. Lower chlorophyll contents were measured but the absence of necrosis symptom and hydration rates of aerial parts above 70% suggested physiological adaptation of plants to the FA substrate. Moreover, significant organic carbon inputs could be measured in FA leachates after 17 weeks of laboratory cultivation, which could be related to the establishment of MxG rhizosphere. Besides, the emergence of specific bacterial phylotype could be reported at the FA-root interface. Analysis of FA leachates in planted pots also showed marked decreases of nitrate but increases of nitrite contents, indicating a nitrogen cycle restart. Field trials confirmed the growth potential of MxG directly on FA, without any requirement of additional landfill soil amendment. Finally, we believe that fly ash revegetation with MxG could be an effective strategy for cost effective and long term FA disposal site rehabilitation.     

摘穗与秸秆粉碎复式作业机构设计与试验

设计了一种摘穗与秸秆粉碎复式作业机构.该机构主要由摘穗板、一对拉茎辊和一个切割刀辊组成.拉茎辊带有凸棱,凸棱上按一定间隔设有开口,切割刀辊上装有缺口圆盘刀片,刀片与拉茎辊凸棱的开口配合,茎秆下拉时,切割刀辊将茎秆切碎,一套机构实现摘穗和秸秆切碎2个功能.建立了茎秆下拉运动方程,分析了茎秆在机构间的运动规律,理论上证明了茎秆下拉的运动轨迹具有较好的直线度.初步试验表明,该机构的摘穗效果良好,籽粒损伤率和果穗损失率低、茎秆折断减少,功耗是摘穗机构与秸秆切碎机构分置时的35％,节能效果显著.     

中国与美国及新西兰牛奶兽药残留监测计划的比较

目的：比较中国与美国及新西兰牛奶兽药残留监测计划的差异和不足,为完善我国牛奶兽药残留监测计划提供参考。方法：收集2008-2011年中国、美国及新西兰的牛奶兽药残留监测计划的数据,比较各个国家实施监测计划的药物种类、样本量以及实施结果。结果：我国与美国及新西兰牛奶兽药残留监测计划相比,监测药物种类与美国及新西兰相近,但检测量少,难以覆盖所有牧场;2011年度的中国与美国及新西兰牛奶抗生素残留监测的检测结果为：中国的检出率高于美国和新西兰（P〈0．05）,有统计学意义。建议在监测计划中扩大监测范围,增加检测量,使监测计划能覆盖更多地区和牧场。