Causes of Decadal Climate Variability over the North Pacific and North America

The cause of decadal climate variability over the North Pacific Ocean and North America is investigated by the analysis of data from a multidecadal integration with a state-of-the-art coupled ocean-atmosphere model and observations. About one-third of the low-frequency climate variability in the region of interest can be attributed to a cycle involving unstable air-sea interactions between the subtropical gyre circulation in the North Pacific and the Aleutian low-pressure system. The existence of this cycle provides a basis for long-range climate forecasting over the western United States at decadal time scales.     

Atmospheric new particle formation enhanced by organic acids

Atmospheric aerosols often contain a substantial fraction of organic matter, but the role of organic compounds in new nanometer-sized particle formation is highly uncertain. Laboratory experiments show that nucleation of sulfuric acid is considerably enhanced in the presence of aromatic acids. Theoretical calculations identify the formation of an unusually stable aromatic acid-sulfuric acid complex, which likely leads to a reduced nucleation barrier. The results imply that the interaction between organic and sulfuric acids promotes efficient formation of organic and sulfate aerosols in the polluted atmosphere because of emissions from burning of fossil fuels, which strongly affect human health and global climate.     

Delay of disease development in transgenic plants that express the tobacco mosaic virus coat protein gene

A chimeric gene containing a cloned cDNA of the coat protein (CP) gene of tobacco mosaic virus (TMV) was introduced into tobacco cells on a Ti plasmid of Agrobacterium tumefaciens from which tumor inducing genes had been removed. Plants regenerated from transformed cells expressed TMV mRNA and CP as a nuclear trait. Seedlings from self-fertilized transgenic plants were inoculated with TMV and observed for development of disease symptoms. The seedlings that expressed the CP gene were delayed in symptom development and 10 to 60 percent of the transgenic plants failed to develop symptoms for the duration of the experiments. Increasing the concentration of TMV in the inoculum shortened the delay in appearance of symptoms. The results of these experiments indicate that plants can be genetically transformed for resistance to virus disease development.     

半干旱地区八种杨树无性系间苗期净光合速率变化的研究*

辽宁省建平县半干旱地区不同来源的８种杨树无性系净光合速率（Ｐｎ）达到了显著和极显著的差异水平，无性系间的净光合速率可分为高中低三个类群，即：昭林场６号、群众杨、赤峰杨３４号、欧症状杨４７、小黑肠、小青杨、帝国杨５１号、欧美杨６４。具高光合速率的昭林场６号，受光量作用大，但受湿度、空气蒸汽压影响小，适应于具有干热天气的半干旱地区；而低光合类群的三个无性系则不同，其中欧美杨６４一直与光、湿度和蒸汽压的     

Root carbohydrate reserves, mineral nutrient concentrations and biomass in a healthy and a declining sugar maple (Acer saccharum) stand

Soil and root characteristics were contrasted between a "declining" and a "healthy" sugar maple (Acer saccharum Marsh.) stand in Vermont, USA. The declining stand had lower basal area increment and more crown dieback than the healthy stand. Soil pH and base cation content were lower and soil water content was higher at the site of the declining stand than at the site of the healthy stand, whereas soil temperature did not differ significantly between the sites. In live fine roots, concentrations of K and Ca were marginally (P < 0.07) lower in the declining than in the healthy stand, whereas concentrations of N, P, Mg, and Al were not significantly different (P = 0.13 to 0.87) between stands. Starch and soluble sugar concentrations of fine and coarse roots did not differ significantly between stands, indicating that crown dieback did not affect carbohydrate supply to the roots in the declining stand. Throughout the growing season, the standing live and dead root biomass were significantly higher in the declining stand than in the healthy stand, indicating that more carbon was allocated to roots and that root turnover was higher in the declining stand than in the healthy stand.     

High genetic diversity of Fusarium circinatum associated with the first outbreak of pitch canker on Pinus patula in South Africa

The disease known as pitch canker results from infection of Pinus species by the fungus Fusarium circinatum. This fungus also causes a serious root disease of Pinus seedlings and cuttings in forestry nurseries. Pinus radiata and P. patula are especially susceptible to the pathogen, but there are no records of pitch canker on P. patula in established plantations. To date, only planting material of this tree species in nurseries or in plantations at the time of establishment have been infected by F. circinatum. Symptoms of pitch canker have recently emerged in an established P. patula plantation in South Africa and this study sought to determine whether the symptoms were caused by F. circinatum. Isolates from cankers were identified as F. circinatum using morphology and DNA-based diagnostic markers. Microsatellite markers were then used to determine the genetic diversity of a collection of 52 isolates. The entire population included 17 genotypes representing 30 alleles, with a greater number of genotypes collected from younger (three- to six-year-old) than older (12- to 19-year-old) trees. Both mating types of F. circinatum were present, but no evidence of sexual recombination was inferred from population genetic analyses. This is the first record globally of pitch canker on P. patula trees in managed plantations. It is of significant concern to South Africa, where P. patula is the most important Pinus species utilised for plantation forestry.     

Using an unmanned aerial vehicle to evaluate nitrogen variability and height effect with an active crop canopy sensor

Ground-based active sensors have been used in the past with success in detecting nitrogen (N) variability within maize production systems. The use of unmanned aerial vehicles (UAVs) presents an opportunity to evaluate N variability with unique advantages compared to ground-based systems. The objectives of this study were to: determine if a UAV was a suitable platform for use with an active crop canopy sensor to monitor in-season N status of maize, if UAV’s were a suitable platform, is the UAV and active sensor platform a suitable substitute for current handheld methods, and is there a height effect that may be confounding measurements of N status over crop canopies? In a 2013 study comparing aerial and ground-based sensor platforms, there was no difference in the ability of aerial and ground-based active sensors to detect N rate effects on a maize crop canopy. In a 2014 study, an active sensor mounted on a UAV was able to detect differences in crop canopy N status similarly to a handheld active sensor. The UAV/active sensor system (AerialActive) platform used in this study detected N rate differences in crop canopy N status within a range of 0.5–1.5 m above a relatively uniform turfgrass canopy. The height effect for an active sensor above a crop canopy is sensor- and crop-specific, which needs to be taken into account when implementing such a system. Unmanned aerial vehicles equipped with active crop canopy sensors provide potential for automated data collection to quantify crop stress in addition to passive sensors currently in use.     

Effects of Farm Yard Manure and Lime on Cadmium Uptake by Rice Grown in Two Contaminated Soils of Chittagong

A pot experiment was conducted to evaluate the efficiency of farm yard manure （FYM） and lime （calcium carbonate） on reducing the uptake of Cd by rice in two Cd contaminated soils of Chittagong. The effects of farm yard manure, lime and farm yard manure mixed with lime （FYM ＋ Lime） on rice （Oryza sativa L.） growth, Cd uptake by rice and 0.1 N HC1 extractable Cd in soil were investigated. Results showed that addition of lime and farm yard manure mixed with lime significantly decreased 0.1 N HCl extractable Cd in the city sewage soil. Application of farm yard manure significantly decreased Cd concentration in rice in the city sewage soil. Lime and farm yard manure mixed with lime significantly reduced Cd concentration in rice m both the contaminated soils. Lime was more efficient than farm yard manure in reducing the uptake of Cd by rice.     

A high-resolution radiation hybrid map of the human genome draft sequence

We have constructed a physical map of the human genome by using a panel of 90 whole-genome radiation hybrids (the TNG panel) in conjunction with 40,322 sequence-tagged sites (STSs) derived from random genomic sequences as well as expressed sequences. Of 36,678 STSs on the TNG radiation hybrid map, only 3604 (9.8%) were absent from the unassembled draft sequence of the human genome. Of 20,030 STSs ordered on the TNG map as well as the assembled human genome draft sequence and the Celera assembled human genome sequence, 36% of the STSs had a discrepant order between the working draft sequence and the Celera sequence. The TNG map order was identical to one of the two sequence orders in 60% of these discrepant cases.