Correction and updating

In the heading of David Cassidy's review of The Private Lives of Albert Einstein (18 February, p. 997) the price of the book as sold by its British publisher, Faber and Faber, was given incorrectly; the correct price is pound15.99. The book is also to be published in the United States by St. Martin's Press, New York, in April, at a price of $23.95.     

Resources required for global tuberculosis control

We estimate that to achieve the World Health Organization's tuberculosis control targets, the 22 high-burden countries (HBCs) that collectively account for approximately 80% of the world's tuberculosis cases require about $1 billion per year during the period 2001 to 2005. A further $0.2 billion per year is needed for low and lower-middle income countries outside the 22 HBCs. There is a resource gap of up to around $300 million per year. Substantial progress in tuberculosis control could be achieved with increased investment that is large in the context of existing spending, but small in the wider context of global health expenditure.     

美国路易斯安那州的克氏原螯虾产业发展概述

阐述了美国路易斯安那州的克氏原螯虾产业的概况,包括路易斯安那州的螯虾养殖业发展简史、螯虾历年的渔获状况、近十年来的螯虾批发价格统计及典型的养殖模式等,为国内克氏原螯虾业发展提供借鉴。     

ECOLOGY: Louisiana's Vanishing Wetlands: Going, Going ..

An ambitious $14 billion plan known as Coast 2050 attempts to protect more than 10,000 square kilometers of Louisiana's wetlands, which are disappearing at a rate of up to 90 square kilometers per year, one of the highest rates of land loss in the world. But a number of unanswered scientific questions swirl around the plan. And it could run afoul of powerful interests in the shipping, petroleum, and fishing industries.     

Erratum

The cost of semiconductor grade silicon was incorrectly stated as $65 per ton (29 July, p. 446). The correct figure is $65 per kilogram.     

灵岩乡晓营村发展城郊型农业的调查与启示

人均耕地不到1000 m~2亩的晓营村,因地制宜开发低洼地和水面资源,大力发展蔬菜、渔业生产,两项收入320万元,达农业总收入的82％;人均渔业、菜收入逾1200元,20％的农户成为蔬菜、渔业万元户,农业经济效益的提高促进了村办工业的技术改造,并兴办了合资企业;晓营人还迈出家门,到县城、省城乃至上海开店经商,走出了一条“以农促工,以农促商”,贸工农全面发展的新路子。     

浙江省小型建网渔具渔法调查分析

于2010年1-6月对浙江省小型建网渔具渔法进行了初步的调查。调查结果表明：浙江省小型建网主体结构一致,由墙网、网圈、升网、网囊、倒网和附属渔具组成;小型建网在温州市、台州市、宁波市和舟山市均有分布;渔获物多为岩礁鱼类。     

胡子鲇鱼种的培育试验

利用池塘将全长2cm的胡子鲇（Clarias fuscus）鱼苗培育成全长6～8cm的鱼种,放养密度为150尾/m^2.试验结果,成活率达60%以上,经济效益较好,说明利用池塘合理密养进行胡子鲇鱼种的培育是可行的.     

广西公益林生态效益补偿研究

为了研究合理的公益林生态效益补偿标准,维持公益林的经营动力,该文采用林木资产评估方法和本金折息法,并以价值损失补偿计量标准,计算公益林生态效益补偿金额.结果表明:①如果政府一次性购买广西集体和个人经营的公益林归国家所有,对公益林经营者进行补偿所需的补偿金额为220亿元人民币;②如果公益林产权不变,仍由所有者按公益林建设规程进行经营,保证公益林正常发挥生态效益,每年对公益林经营者进行补偿所需的补偿金额为7.22亿元人民币.各树种类型公益林补偿标准为:杉木236.0元/(hm2·a)、马尾松214.4元/(hm2·a)、阔叶树219.1元/(hm2·a)、桉树195.4元/(hm2·a)、竹林87.4元/(hm2·a)、灌木林39.1元/(hm2·a).公益林有典型的外部经济性,政府必须对公益林经营者进行合理的经济补偿才能维持公益林的经营动力.      

1961—2015年各国化肥消费量与人均GDP相关性分析

我国已经连续30年成为世界化肥消费量最大的国家,单位面积化肥施用量也长期居世界高位水平,化肥的过量施用既造成严重的农业面源污染,也制约着我国农业的可持续发展。本研究收集了美国、加拿大等12个典型国家1961—2015年的人均GDP和化肥消费量的时间序列数据,通过回归分析法得出各国人均GDP与化肥消费量显著相关（P<0.05）,发达国家的人均GDP在8000~13 000美元区间时,化肥消费量由增长阶段进入稳定或降低阶段。从我国目前人均GDP（>8000美元）的发展水平与世界发达国家化肥的历史消费轨迹来看,我国的化肥消费量已经具备了从增长阶段转变到稳定阶段的条件。     

An intercontinental array--a next-generation radio telescope

It is difficult to estimate accurately the cost of constructing a large scientific instrument that involves many techniques. On the other hand, most of the component parts of the VLBA consist of antennas and electronic systems that already exist or are being fabricated. The kind of 25-m antennas being constructed for the VLA will cost about $900,000 each and will work at wavelengths as short as 1 cm. A multifrequency radiometer, hydrogen maser frequency standard, small control computer, control building, and wide-band instrumentation recorder bring the cost to about $1.5 million per element, or $15 million for a ten-element array using tape recorders. A multistation playback facility, with ten recorders and enough correlators to handle all interferometer pairs simultaneously, together with the necessary computers to control the processor and reduce the data, may add $5 million. The total cost is thus about $20 million at current prices, including an adequate supply of magnetic tape. This is comparable to the cost of existing large radio telescopes and arrays. An array that used a geostationary communication satellite to transmit the data to a real-time correlator would cost $30 million to $50 million more, but this is still within the price range of other space astronomy projects. It is thus feasible to construct at reasonable cost an intercontinental very long baseline array which has sub-milliarcsecond resolution. This would complement the Very Large Array now being constructed (4), which is much more sensitive to objects of low surface brightness. This next step would permit the study of the universe with unprecedented angular resolution.     

舟山沿岸小型建网及张网资源友好性研究

根据2011年5-11月舟山沿岸小型建网及定置张网的渔获物数据,结合2种作业渔具结构原理,分析其对渔业资源的利用效率,对幼鱼资源的损害程度。结果表明,张网网目尺寸较小,对幼鱼资源的损害程度较大,小型建网渔具结构设计较合理,对资源更具友好性。建议相关部门对2种渔具科学化管理,正确引导,合理使用。     

Economics of Variable Rate Lime in Indiana

In Indiana, variable rate application (VRA) of lime is often considered a good place to start site-specific management (SSM). This is because soil pH is one of the most variable of manageable soil characteristics in the state, the availability of essential nutrients is closely related to soil pH, and because spreaders can be retrofitted relatively inexpensively to do VRA. The objective of this study is to evaluate the profitability of VRA for lime as a stand-alone activity. The methodology involves a spreadsheet model using corn and soybean pH response functions estimated with small plot data. The overall results indicate increased annual returns to corn and soybean production with site-specific pH management strategies. On average, SSM with agronomic recommendations provides an increased annual return of $7.24 per hectare (ha) (+1.78%). SSM with the economic decision rule provides an average increase in annual return of $19.55 ha^–1 (+4.82%). Information strategy, which uses site-specific information to determine the economically optimal uniform rate of lime, provides an average increase in annual return of $14.38 ha^–1 (+3.54%).     

The tokamak: model T fusion reactor

During the past several years there have been significant scientific and technological advances related to the tokamak magnetic confinement scheme. These are summarized in the context of a recent tokamak reactor design study which emphasizes reduced size, higher power density, and enhanced plant reliability and maintainability relative to earlier tokamak reactor design studies. The direct plant cost of the proposed reactor is estimated to be in the range $1000 to $1500 per electrical kilowatt. A three-phase strategy for demonstrating tokamak fusion power generation at a committed site is outlined. It is estimated that implementation of the three-phase program would require about 20 years and a total escalated expenditure $10 billion to $15 billion. The tokamak power plant described here is not viewed as definitive but rather as a point of departure in the development of a plan to demonstrate tokamak power generation.     

Recent progress in the direct liquefaction of coal

Interest in direct coal liquefaction steadily decreased during the 1980s as the price of crude oil dropped; there is now only one integrated coal liquefaction pilot plant active full time in the United States. The economics derived early in the decade established the price of transportation fuels from coal at $80 per barrel or higher. However, there have been dramatic improvements in the technology since 1983 that have not been widely appreciated. Recent designs and cost estimates show that a 60 percent decrease in the cost of liquid fuels from coal to an equivalent of $35 per barrel for crude oil. Although this cost is not low enough to justify immediate commercialization, additional improvements have been identified that could make direct liquefaction an attractive way to produce gasoline and other conventional fuels.     

Areawide suppression of European corn borer with Bt maize reaps savings to non-Bt maize growers

Transgenic maize engineered to express insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) has become widely adopted in U.S. agriculture. In 2009, Bt maize was planted on more than 22.2 million hectares, constituting 63% of the U.S. crop. Using statistical analysis of per capita growth rate estimates, we found that areawide suppression of the primary pest Ostrinia nubilalis (European corn borer) is associated with Bt maize use. Cumulative benefits over 14 years are an estimated $3.2 billion for maize growers in Illinois, Minnesota, and Wisconsin, with more than $2.4 billion of this total accruing to non-Bt maize growers. Comparable estimates for Iowa and Nebraska are $3.6 billion in total, with $1.9 billion for non-Bt maize growers. These results affirm theoretical predictions of pest population suppression and highlight economic incentives for growers to maintain non-Bt maize refugia for sustainable insect resistance management.     

鱼塘浮头预报方法研究

利用2001、2007—2009年监测的溶氧量资料和有关气象资料,对银川市鱼塘溶氧量与气象要素的关系进行了相关分析。结果表明,溶氧量随温度升高而增加,到一定程度后,又会减少,在16℃时溶氧量最大;溶氧量随相对湿度升高而减少;溶氧量随02时气压、风速、光照时数升高而增加。采用逐步回归方法建立了溶氧预报方程,划分了鱼塘浮头级别,经天气形势补充订正后,可较好地预报鱼塘浮头,从而达到科学饲养、趋利避害的目的。     

不同氮素水平和密度下棉花群体光合速率的探讨

1986—1987年对不同氮素水平和密度条件下棉花群体光合速率进行了研究。结果证明,合理增施N素和适当的栽培密度能明显地提高棉花群体的光合能力,这种使棉花群体光合速率提高的效应,还随生育进程而增加。棉花盛花期群体光合速率日变化为“午休型”。棉花群体光合速率与皮棉产量无相关。     

Simultaneously mitigating near-term climate change and improving human health and food security

Tropospheric ozone and black carbon (BC) contribute to both degraded air quality and global warming. We considered ~400 emission control measures to reduce these pollutants by using current technology and experience. We identified 14 measures targeting methane and BC emissions that reduce projected global mean warming ~0.5°C by 2050. This strategy avoids 0.7 to 4.7 million annual premature deaths from outdoor air pollution and increases annual crop yields by 30 to 135 million metric tons due to ozone reductions in 2030 and beyond. Benefits of methane emissions reductions are valued at $700 to $5000 per metric ton, which is well above typical marginal abatement costs (less than $250). The selected controls target different sources and influence climate on shorter time scales than those of carbon dioxide-reduction measures. Implementing both substantially reduces the risks of crossing the 2°C threshold.     

外源增钾缓解铵胁迫下小麦根系受抑

分别对硝态氮($\text{NO}_{3}^{-}-\text{N}$)和铵态氮($\text{NH}_{4}^{+}-\text{N}$)培养下的小麦幼苗进行不同水平的钾处理(低钾,1 mmol·L^-1;正常,3 mmol·L^-1;高钾,6 mmol·L^-1),探究外源供钾对缓解铵胁迫下小麦根系生长受抑的效果与作用机理。结果表明,$\text{NH}_{4}^{+}-\text{N}$条件下,小麦叶片和根系中的$\text{NH}_{4}^{+}$含量较$\text{NO}_{3}^{-}-\text{N}$条件下显著(P<0.05)增加,根系生长受到抑制,与$\text{NO}_{3}^{-}-\text{N}$条件下的植株相比,$\text{NH}_{4}^{+}-\text{N}$条件下相同钾水平的小麦幼苗总根长、根表面积、根体积均显著(P<0.05)减少。随着施钾水平的升高,根系受抑制的情况得到缓解。$\text{NH}_{4}^{+}-\text{N}$条件下,随着施钾水平的升高,小麦幼苗的叶面积、气孔导度、净光合速率显著(P<0.05)升高,叶和根中的可溶性糖含量显著(P<0.05)升高,叶中蔗糖磷酸合成酶(SPS)活性亦显著(P<0.05)增强,根中生长素(IAA)含量及其与细胞分裂素(CTK)的比值升高。据此推断,在铵胁迫下,增钾处理增强了小麦的光合作用,提高了碳水化合物的合成能力,可为$\text{NH}_{4}^{+}$的同化提供更多的碳架,从而降低体内$\text{NH}_{4}^{+}$的积累;同时,促进了根中植物激素的平衡,最终得以缓解铵胁迫下小麦根系生长受到的抑制。