Erratum

According to the latest information the publisher has provided to Science the current price of The Nervous System (Donald B. Tower, Ed.; Raven Press), reviewed by John G. Hildebrand, 22 April 1977, p. 419, is $15 a volume, rather than $25 a volume and $65 for the three-volume set, the prices listed at the head of the review.     

Erratum

In the letter from Keith Bowker concerning journal price increases (30 Oct., p. 597), two conversion rates referred to in the Sixth paragraph were incorrect. The rates should have been $1.69 per pound1 and $1.67 per pound1, respectively.     

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.     

Erratum

In Eliot Marshall's article "California's debate on carcinogens" (News & Comment, 20 Mar., p. 1459), the last sentence of the third paragraph, which refers to fines to be imposed under Proposition 65, should have read, "Companies found guilty of violating it will be charged $2500 a day and legal costs." The article gave the incorrect figure of "$25,000 a day."     

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。     

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。     

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.     

Sediment Movement on the Continental Shelf near Washington and Oregon

The nuclides zinc-65 and cobalt-60 associated with river-borne particulate matter are incorporated in sediment on the Continental Shelf near the Colum- ia River. Changes in the relative concentrations of zinc-65 and cobalt-60 and in the ratio of the activity of zinc-65 and cobalt-60 suggest that radioactive sediment moves northward 12 to 30 kilometers per year along the shelf and 2.5 to 10 kilometers per year westward away from the coast.     

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.     

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.     

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.     

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.     

不同种植方式与密度对玉米产量的影响

为探究种植方式及栽培密度对玉米产量的影响,以黑龙江省第一积温带下限主栽品种兴垦3号（半紧凑型）和江单1号（紧凑型）为试验材料,设置5个栽培密度,采用裂区设计,对黑龙江省常用的5种栽培方式的产量进行比较研究。结果表明：5种栽培方式间的产量达到极显著水平,产量顺序由大到小依次为50cm小垄栽培方式、1465栽培方式、130...     

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.      

Corrections and clarifications

In the News & Comment article "Orphan chimps won't go back to nature" by Virginia Morell (15 July, p. 312), an incorrect figure was given as the dollar amount the Jane Good-all Institute spends on maintaining orphan chimpanzee sanctuaries. The correct figure is $40,000 per month.     

Lunar crust: structure and composition

Lunar seismic data from artificial impacts recorded at three Apollo seismometers are interpreted to determine the structure of the moon's interior to a depth of about 100 kilomneters. In the Fra Mauro region of Oceanus Procellarum, the moon has a layered crust 65 kilometers thick. The seismic velocities in the upper 25 kilometers are consistent with those in lunar basalts. Between 25 and 65 kilometers, the nearly constant velocity (6.8 kilometers per second) corresponds to velocities in gabbroic and anorthositic rocks. The apparent velocity is high (about 9 kilometers per second) in the lunar mantle immediately below the crust.     

The economics of automatic section control technology for planters: A case study of middle and west Tennessee farms

Reducing double-planted area in row crop production fields where planter overlap is unavoidable, such as end rows, point rows, and areas around internal field obstacles, can improve net returns by reducing seed costs and increasing revenue. The objective of this case study was to present a summary of results from 52 fields that highlight potential losses from double-planted areas and therefore potential savings associated with an investment in an Automatic Section Control system (ASC) for planters. Percentage of double-planted area ranged from 0.1% to 15.5% depending on field size and shape. Fields were classified into low, moderate and high double-planted fields, based on percentage of double planted area. Potential savings from adopting ASC system for planters were evaluated using this information. Savings from the adoption of this technology ranged from $4 per ha to $26 per ha depending on the distribution of field types in a farming operation. The results indicated that savings and the minimum period of time over which an investment in ASC on planters would have to be finance to guarantee a positive net cash flow every year was determined by farm size and distribution of field types in a farming operation.     

林药复合经营下不同遮阴度对白芨和黄精生长的影响

林地遮阴度对林下套种的植株生长有着重要的影响,且对不同的中药材有着不同的适 应性特点。本文研究白芨和黄精两个品种在3 种不同强度的遮阴度下成活率、株高、分蘖数及其 产量。结果表明:白芨和黄精在总体上表现为对遮阴度的要求黄精（65～80%）＞白芨（35～ 50%）。在具体指标上,在分蘖数上均表现为一级较低遮阴度的条件下具有更高的分蘖数;在株 高和成活率上,白芨和黄精表现不一致,前者在较低的遮阴度下（35～50%）有更高的株高和成活 率,而后者在较高的遮阴度下（﹥65%）更好;在产量方面,白芨单株重量和亩产量     

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%).     

65 份水稻种质的产量性状遗传多样性分析

以65份来自种质资源库的水稻品种为材料,根据品种的产量性状进行统计分析、多样性指数分析以及相关性分析。结果表明,供试材料在产量性状上存在丰富的遗传多样性,多样性指数介于1.607~2.000之间,单株产量与单株有效穗数、每穗实粒数及穗着粒数存在极显著的正相关,相关系数分别为0.346、0.586和0.508;聚类分析结果表明,65个水稻材料可聚为22个类群,说明供试材料的遗传距离较远,种质资源分化程度较高;通过主成分分析,获得3个主成分,累积贡献率达到85.212%,并通过对应的特征向量获得3个主成分因子,分别为粒数因子、结实率因子及有效穗数因子,可以作为种质资源综合评价指标。通过每个品种的各主成分排名及综合排名对各品种进行综合评价,排前5名的水稻材料分别为奥野占6号、R995、油粘8号、丝苗12和R998。在水稻育种中应注意利用具有丰富遗传多样性的种质资源,并在亲本选配时选择遗传距离较远且综合性状表现差异较大的种质材料。