Ballistic 2-d imaging through scattering walls using an ultrafast optical kerr gate

An ultrafast optical shutter was used to image ultrasmall objects hidden behind scattering walls by a procedure that selects in time the ballistic component and rejects the scattered diffusive light. Scattering walls used in this experiment included human breast tissue, chicken breast tissue, and a water suspension of polystyrene particles with scattering coefficients up to 21.7. Submillimeter resolution was achieved for two-dimensional ballistic images of a single point, a double-point fluorescence source, and a bar test chart in or behind these different turbid media.     

Comparative study of Kenaf varieties and growing conditions and their effect on kraft pulp quality

Kenaf (Hibiscus cannabinus L.) is an annual plant which produces a very high fiber yield per hectare and has demonstrated to be a suitable material for pulping. The crop conditions influence fiber production, but there is no information about their effect on pulp quality. The aim of this work was to study the effect of kenaf varieties and crop conditions (watering dose and harvesting time) on sulfate pulp quality. The study has been made on bast fiber sulfate pulps due to their high added value. The quality criteria were fiber dimensions, chemical composition and pulp quality. Kenaf variety or crop conditions have significant effect on fiber dimensions, holocellulose content, kappa number and breaking strength. To obtain high fiber yield and good delignified pulps it is recommended to grow the Salvador variety and to employ advance harvesting. Received: 20 January 1999     

Bird-mediated effects of pest control services on crop productivity: a global synthesis

Journal of Pest Science - Birds provide important ecosystem services in many ecosystems, including important pest control effects on productive systems. The typically low bird diversity observed in...     

Rapid method of determining pollen incompatibility in Chrysanthemum morifolium Ramat

Summary A classification system for predicting high, medium and low seed set from Chrysanthemum morifolium crosses was developed. Stigmas collected and preserved 8 days after pollination were examined with a binocular microscope for adhering pollen grains. Florets from compatible crosses had brown stigmas with pollen grains attached and embryo development while florets from incompatible crosses had white stigmas with no or rarely 1 or 2 pollen grains attached and no embryo development. Using this method the occurrence of seed set was predicted with 78.5% accuracy in one year and 89% in the following. This provides a method of determining the compatibility of a chrysanthemum cross without waiting the 1 to 2 months required for seed ripening.Scientific Journal Series Paper Number 7570 of the Minnesota Agricultural Experiment Station.     

The ecological role of bivalve shellfish aquaculture in the estuarine environment: A review with application to oyster and clam culture in West Coast (USA) estuaries

Aquaculture is viewed as a potential mechanism to meet the growing demand for seafood around the world. The future of bivalve shellfish aquaculture in the U.S. hinges on sustainable practices on the part of industry and a more consistent regulatory regime. Bivalve shellfish aquaculture is a recent practice relative to its history in other countries, beginning in the late 1800s along the U.S. West Coast where it is now well established with farm raised product utilizing land-based hatcheries and grow-out directly in numerous estuaries. Bivalve shellfish aquaculture can be viewed as a disturbance which modifies the estuarine system in three ways: 1) changes in material processes — bivalves process food and produce wastes; 2) addition of physical structure — aquaculture introduces the cultured organisms and in some cases a physical anchoring structure; and 3) pulse disturbances like harvest and bed maintenance disturb sediments, remove species in addition to the cultured organisms themselves, and change resource or habitat availability. In U.S. West Coast estuaries, water column and sediment nutrient concentrations are relatively high and influenced by large tidal exchange and proximity to deeper nearshore ocean waters where upwelling controls production during summer months. Bivalves are unlikely to influence material processes except at local bed scales in these systems, although estuary-wide effects could appear as the fraction of cultured area rises or in poorly flushed bays. Bivalve culture clearly modifies estuarine habitat at local community and at landscape scales and effects are most often evaluated against existing structured habitat in the form of submerged aquatic vegetation. Individual activities act as pulse disturbances and the recovery of eelgrass (Zostera marina) to pre-disturbance levels is variable (< 2 to > 5 years). The extent of disturbance depends on the aquaculture practice and the distribution of eelgrass reflects a balance of space competition, pulse disturbance and recovery, and is therefore at dynamic equilibrium on aquaculture beds. Structure provided by aquaculture appears functionally similar to eelgrass for small benthic infauna and mobile epibenthic fauna while use of aquaculture as habitat by larger more mobile invertebrates and fish depends on mobility and varies with life-history stage and taxon being evaluated. Scale seems a very important management consideration and further research at estuarine landscape scales, especially for habitat use by important invertebrates and fish, may prove useful in designing and implementing best management practices. Though local and short term effects from aquaculture are clearly evident in U.S. West Coast estuaries, bivalve aquaculture does not remove area from the estuary or degrade water quality like other anthropogenic influences, and thus has not been implicated in shifts to alternate states or reduced adaptive capacity of the larger ecological system.     

2005-2020年转Bt基因棉花抗虫性变化及其与产量性状的相关性分析

为了给转Bt基因棉花在科研和生产上多世代可持续利用提供依据,以转Bt基因棉花品种银山8号为试验材料,从2005年开始,连续16年进行跟踪研究。结果表明,随种植世代的增加,生物测定银山8号第2～4代棉铃虫幼虫校正死亡率、铃期叶片和铃期小铃杀虫蛋白表达量均有不同程度的线性上升趋势,同时皮棉产量线性回归也呈增长趋势;苗期叶片、蕾期叶片和蕾期小蕾杀虫蛋白表达量呈线性下降趋势。相关性分析表明,抗虫棉的抗虫性与皮棉产量间均呈正相关,株铃数和衣分是构成皮棉产量的重要因子,与皮棉产量的相关性分别达到极显著和显著水平。外源Bt基因转入棉花后能稳定遗传给后代,通过卡那霉素鉴定和系统选择可以持续保持转Bt基因棉花多世代的抗虫性,甚至通过提纯复壮逐年优选,可实现转Bt基因抗虫棉特定生育时期或部分棉花器官抗虫性的提高。     

Update on the 35‐year expansion of the invasive root pathogen,Phytophthora lateralis,across a landscape of Port Orford cedar (Chamaecyparis lawsoniana)

Port Orford cedar (Chamaecyparis lawsoniana) is endemic to northern California and southwestern Oregon and is considered a foundation species that plays critical roles in riparian areas and on nutrient‐poor soils. Since 1952, a non‐native, pathogenic oomycete (Phytophthora lateralis) has been spreading throughout the range of the cedar. Most spread occurs by vehicles carrying infested soil along gravel roads primarily used for timber harvest. In a previous study conducted in 1998 and 1999, Port Orford cedar and P. lateralis were censused in a 37‐km² study area and dendrochronology was used to reconstruct the history of pathogen invasion. That work, which represents the only detailed analysis of spread rates for P. lateralis, showed that the first successful invasion into the study area took place in 1977 and that 43% of the susceptible host sites (stream crossings) were infested by 1999. In the work presented here, all sites that were uninfested in 1999 were re‐censused in 2012, extending the historical reconstruction of P. lateralis spread to 35 years. Two new infestations were initiated between 1999 and 2012, suggesting that the rate of spread of P. lateralis has slowed greatly. Between 1980 and 1989, the average number of new site infestations was 1.8 infestations per year, while between 1990 and 1999 the average was 0.4 infestations per year and between 2000 and 2009 the average was 0.2 infestations per year. Several potential explanations for the reduced number of new infestations are discussed.