非奇异M-矩阵Hadamard积的最小特征值的改进估计式

根据矩阵的Hadamard积和最小特征值的定义以及M-矩阵的性质特点,对不同情况下最小特征值τ(BA-1)和τ(AA-1)做了进一步研究(A,B为非奇异M-矩阵),给出了最小特征值τ(BA-1)和τ(AA-1)2个改进估计式,并从理论上证明了新估计式在一定条件下改进了现有文献的结果。数值算例结果也验证了新估计式改进了Fiedler和Markham的猜想以及现有文献的结果,提高了现有估计式的估计精确度。     

M-矩阵与其逆矩阵的Hadamard积最小特征值下界的估计

关于M-矩阵A与其逆矩阵的Hadamard积A.A-1,利用Gerschgorin圆盘定理给出了A.A-1的最小特征值下界的一些新的估计式,改进了Fiedler和Markham的猜想.     

M-矩阵Hadamard积的新估计

M-矩阵的Hadamard积是一种特殊的矩阵乘积,具有广泛的重要应用背景,概率统计、经济学、组合论、生物学和社会科学等领域中的许多问题都与它有着密切的联系,受到很多专家学者的关注和研究。首先介绍相关定义和性质,其次应用矩阵特征值包含域定理,结合非奇异M-矩阵的性质及其逆矩阵元素的特点,给出不同情形下2个M-矩阵的Hadamard积的最小特征值的几个新估计式。并用理论分析和算例表明新估计式在某些情况下比现有的估计结果更精确,给出的估计式改进了一些现有的结果。     

矩阵Hadamard积特征值的估计

利用矩阵有向图上的k-path覆盖,给出了非负矩阵Hadam ard积的最大特征值上、下界的估计式,改进了相关结果,使估计更具优越性.     

非负矩阵最大特征值的新界值

非负矩阵最大特征值的估计是非负矩阵理论研究的重要组成部分.如果上下界能够表示为非负矩阵元素的易于计算的函数,那么这种估计价值更高.本文通过构造两个收敛的序列得到非负矩阵最大特征值的新界值.数值算例表明其结果比有关结论更加精确.     

可交换幂等矩阵的性质及推广

幂等矩阵以及它们线性组合的性质在矩阵理论和概率统计中都有重要的应用。在满足AB=BA的条件下分别给出当A为幂等矩阵,B为任意方阵时,线性组合k1A+k2B为幂等矩阵的充分必要条件,并且利用该结果直接得出当A、B均为幂等矩阵时,A与B的和、差、积仍为幂等矩阵的条件;A与B的和、差、积的值域、核,分别与A,B的值域、核之间的关系;当A为幂等矩阵,B为任意方阵时,A的值域与核分别是B的不变子空间的充分必要条件。     

非负矩阵谱半径的上界估计

非负矩阵的谱半径估计是非负矩阵理论研究的重要课题之一.如果谱半径的上界能够表示为非负矩阵元素的易于计算的函数,那么这种估计价值更高.结合非负矩阵的迹分两种情况给出非负矩阵谱半径的上界序列,并且给出数值例子加以说明.     

实广义正定矩阵的若干性质

矩阵∈AR~(n×n)称为实广义正定矩阵,如果对任意非零向量 X∈R~n,有XTAX>0成立。本文讨论了矩阵的kronecker积。Hadamard积和矩阵乘积的正定性,给出相应一些性质。     

正定矩阵几个重要不等式的推广

将正定矩阵中的Hadamard不等式、Oppenhein不等式和Minkowski不等式推广到M-矩阵以及与之相关的逆M-矩阵范围内,并得到一些重要结果。     

非负不可约矩阵Perron根的上界

非负矩阵在数学物理、控制论、电力系统理论等领域有广泛的应用.非负矩阵Perron根的估计是矩阵分析理论研究中的重要问题.利用M-矩阵与非负矩阵之间的关系,给出计算非负不可约矩阵Perron根上界的一种新算法,数值例子表明该算法具有可行性.     

容器规格与基质配比对美国蜡梅容器苗生长的影响

为加快新优花灌木美国蜡梅的引种驯化,以美国蜡梅一年生苗为试验材料,进行容器规格与基质配比的双因素试验,通过测定形态及生理指标,筛选适宜组合。容器规格(A)3种(A_1:12 cm×18 cm;A_2:14 cm×18 cm;A_3:16 cm×18 cm),基质配比(B)3种,(B_1园土:泥炭:珍珠岩为1:0:0;B_2为2:1:1;B_3为1:2:1)。结果显示,两因素对各指标影响差异显著,其交互效应也有一定影响。增大容器规格,增加泥炭的体积比可促进生长,提高苗木质量,同时还利于分蘖。出于经济考虑,A_2规格、B_2基质最为适宜。A_1B_1处理各指标最小;A_3B_3组合苗木质量最佳,地径7.87 mm,生物量18.8 g,质量指数0.19,叶绿素总量、可溶性糖和可溶性蛋白含量分别为2.21 mg·g~(-1)、3.78%和10.83mg·g~(-1);A2B3、A_2B_2与A_3B_2组合次之,前者可节省空间,后者可节省泥炭使用量,可依生产需求选择。     

基于渔捞日志的长江靖江段刀鲚渔获量的时空特征分析

江苏靖江段位于近长江口段,是长江刀鲚渔汛最集中的水域。为了弄清靖江段刀鲚的渔汛特征,本文于2008-2009年和2012-2013年对16艘持刀鲚捕捞许可证的渔船作了渔获量监测,分析了渔获量的时空变化及其环境影响。结果表明,靖江段单船日渔获数量NB和重量WB分别为(21±38)ind./d和(2.0±4.1)kg/d,单船全汛总渔获尾数Nt和重量Wt为(890±929)ind.和(92.3±91.1)kg。NB和Nt具有一致性的年变化趋势,以2013年的最大,其他年份比较接近。但WB和Wt的年变化趋势与渔获数量的年变化趋势有所不同,表现为2008-2012年间持续下滑,2013年显著增长。NB和WB在2-3月间均极低,但4月增至(23.0±31.3)ind./d和(2.4±3.5)kg/d,5月达(78.0±81.0)ind./d和(7.7±9.1)kg/d。ANOVA分析显示,西水域的年NB和WB分别为东水域的2.5和2.7倍。研究亦显示,靖江段刀鲚的WB与同日水温和最高潮位均呈极显著的正相关(P﹤0.05)。长江口外的水温提升,可能是刀鲚开始生殖洄游的重要环境诱导因子。而高潮期在靖江段出现最高渔汛,可能是因为所采用的固定刺网过滤了更多的江水所致。     

Social and environmental attributes of food products in an emerging mass market: Challenges of signaling and consumer perception, with European illustrations

This paper focuses on the environmental and ethical attributes of food products and their production processes. These two aspects have been recently recognized and are becoming increasingly important in terms of signaling and of consumer perception. There are two relevant thematic domains: environmental and social. Within each domain there are two movements. Hence the paper first presents the four movements that have brought to the fore new aspects of food product quality, to wit: (1) aspects of environmental ethics (organic agriculture and integrated agriculture), and (2) social ethics (fair trade and ethical trade). Next, it describes how the actors in the movements (producers, retailers, NGOs, and governments) are organized and how consumers perceive each of the movements. From the perspective of the actors in the movements themselves, the movements are grouped into two “actors’ philosophies.” The first is a “radical” philosophy (the organic production and fair trade movements that arose in radical opposition to conventional agriculture or unfair trade relations), and the second is a “reformist” philosophy (the integrated agriculture and ethical trade movements that arose as efforts to modify but not radically change conventional agriculture). From the point of view of consumers, the classification of the movements is based on perceptions of the “domain” of the movements. That is, consumers tend to perceive the organic production movement and the integrated agricultural movement as a single group because they both deal with the environment. By contrast, consumers tend to group the fair trade movement and the ethical trade movement together because they both deal essentially with social ethics. Recently, key players such as large retailers and agribusinesses have adopted as part of their overall quality assurance programs both environmental and ethical attributes. Their involvement in and adoption of the goals of the movements have, however, generated tensions and conflicts. This is particularly true within the radical movements, because of concerns of cooptation. Finally, the paper identifies challenges faced by those promoting food products with environmental and social/ethical attributes as they attempt to communicate coherent signals to consumers at this crucial moment in the emergence of a mass market for these products. Jean -Marie Codron is a Senior Researcher at INRA and co-director of MOISA, a public joint research laboratory involved in the social sciences. His research interests focus on three main lines of research: economics of contracts, economics of the firm, and economics of market institutions, with applications to “complex” food sectors, where product quality is difficult to measure and/or to signal to the consumer. Lucie Sirieix is Professor of Marketing and Consumer Behaviour at SupAgro Montpellier, France, a national higher education establishment under the Ministry of Agriculture, Fisheries and Food. Within the MOISA research unit, her main research topics are variety seeking, risk and trust, environmental and ethical consumer concerns, and sustainable consumption. Her specific research areas include organic products, fair trade, and regional products. Thomas Reardon is Professor of Agricultural Economics at Michigan State University. His work focuses on globalization, consolidation in the retail and processing sectors, and their effects on agrifood systems and trade as well as on the economics of private quality and safety standards.     

三种环境材料复合对土壤水肥保持同步增效的影响

为研发基于功能互补的不同环境材料复合对土壤水分和氮磷肥保持增效的同步效应,本文选取保水剂(A)、腐植酸(B)和沸石(C),通过室内土柱模拟方法,采用正交实验设计,探究3种不同环境材料复合对土壤水分和氮磷肥保持同步增效的主次和不同目标的组合优化,最终获得提高土壤水分和土壤氮磷保持增效的最优组合,通过过程分析探讨不同环境材料对土壤水肥保持的效应机理。结果表明:3种环境材料复合对土壤水分和氮磷肥保持增效有明显效果,对水分保持和氮磷肥同步增效的最优组合为A3B3C2(即保水剂、腐植酸和沸石添加量为1.5、1.5 g·kg~(-1)和9.0 g·kg~(-1)),该组合相比CK的土壤水分淋出量减少3.5%,氮素淋出量减少12.1%,磷素淋出量增多65.5%;比较发现,沸石对土壤淋溶液p H和EC值影响最大,保水剂居中,腐植酸作用最小;3种环境材料的添加可增加土壤孔隙度,改善土壤团粒结构,具有改良土壤的效应。研究结果为新型肥料研发提供重要参考。     

Is HACCP Nothing? A Disjoint Constitution between Inspectors, Processors, and Consumers and the Cider Industry in Michigan

The transmission of a product or idea from one culture or point of origin to another and the maintenance of control outside the new locality has been referred to as the distribution and maintenance of “nothing.” This perspective has been used to describe the global marketplace and the influence of large multinational corporations on the politics and cultures of host countries. This paper uses this concept, but within a much smaller context. Using the sensitizing concept of a “disjoint constitution,” we interviewed health inspectors and apple cider producers in Michigan to determine if the implementation of the Hazard Analysis and Critical Control Points (HACCP) program designed to ensure food safety was characterized by a power differential that would favor the inspectors. In addition, a larger survey of processors and an internet survey of apple cider consumers was conducted to supplement this data. It was found that HACCP had characteristics of both “nothing” and “something” and that better communication is needed between these groups to move it further along toward the something end of the continuum. Toby A. Ten Eyck is an Associate Professor in the Department of Sociology and affiliated with the National Food Safety and Toxicology Center at Michigan State University. His work focuses on the development, dissemination, and interpretation of mass media risk messages. Donna J. Thede completed her Ph.D in Food Science partially through this research project and is now a Senior Scientist in Nutrition & Regulatory Affairs with the Kellogg Company.  Gerd Bobe conducts research on nutrition and cancer as a fellow in the Cancer Prevention Fellowship Program, Division of Cancer Prevention, National Cancer Institute, National Institutes of Health (Bethesda, Maryland). Previously, he evaluated food safety policies for the Department of Food Science and Human Nutrition and the National Food Safety and Toxicology Center at Michigan State University. Leslie D. Bourquin is an Associate Professor in the Department of Food Science and Human Nutrition and is affiliated with the National Food Safety and Toxicology Center and Food Safety Policy Center at Michigan State University. His research examines factors influencing the effective implementation of food safety standards and the ultimate impacts of these standards on public health.     

凹叶厚朴用于细胞悬浮培养的愈伤组织的制备研究

目的 研究凹叶厚朴适用于细胞悬浮培养的愈伤组织。方法 通过对基本培养基（B₅、MS和1/2MS）、外植体（茎段、顶芽和叶片）、激素浓度及组合进行筛选的方法进行厚朴愈伤组织诱导和继代研究。结果 B₅ 为最适合厚朴愈伤组织诱导的基本培养基;顶芽是最佳诱导愈伤组织的材料;最适合厚朴愈伤组织诱导的培养基为B₅+2.0 mg/L 2,4-D+1.0 mg/L 6-BA;最佳继代培养基为B₅+2.0 mg/L NAA+1.0 mg/L 6-BA,愈伤组织生长倍数达到2.87倍。结论 初步筛选出凹叶厚朴用于细胞悬浮培养的愈伤组织,为凹叶厚朴细胞培养奠定基础。     

Bringing Southeast Asia to the Southeast United States: New forms of alternative agriculture in Homestead,Florida

Immigrant farmers from Southeast Asia have brought knowledge of tropical fruit and vegetable production from their home countries to Homestead, Florida. They have developed a new style of farming, one that most closely resembles agricultural systems described as “homegardens.” Although biodiverse agricultural systems are generally thought to be commercially unviable, homegarden farmers successfully manage crop diversity as an economic strategy. By focusing on growing a mixture of specialty Southeast Asian herbs, fruits, and vegetables, the farmers have created their own economic niche and have shielded themselves from the competition of high-volume, single commodity producers. This paper shows that the Homestead homegardens constitute an alternative form of agriculture that is defined by their agroecological and socioeconomic attributes. It also shows that although the homegarden farms are a form of “alternative agriculture,” they do not operate outside of conventional, global systems of agricultural trade; rather the homegarden farms are embedded in global agriculture. The Homestead case problematizes the tendency to delineate between the global and local scales, and alternative and conventional sectors in agriculture today. This paper concludes that the emergence of the Homestead homegardens can only be understood by taking a place-based approach to studying the environment in which the homegardens are situated as well as identifying the large-scale influences on Miami-Dade County. Valerie Imbruce holds a PhD in plant sciences from a joint program between the Graduate Center of the City University of New York and the New York Botanical Garden. She has conducted research on global agricultural systems in New York City, south Florida, and Central Honduras.     

痂状炭角菌鉴定、培养条件优化及发酵产物活性分析

【目的】炭角菌属具有珍贵的药用价值和较高的经济价值。本研究对采自白蚁废弃巢穴上的炭角菌菌株进行鉴定,对其液体发酵和固体培养条件进行优化,并对液体发酵产物抗菌、抗氧化活性进行测定,以期为痂状炭角菌的开发利用提供参考。【方法】通过形态观察及ITS序列测序对炭角菌进行鉴定;探讨液体发酵中添加不同碳源、氮源和金属离子对痂状炭角菌菌丝体生长的影响;分析固体培养基中添加氨基酸对无性子座生长的影响;利用平板抑菌法和DPPH法对液体发酵产物抗菌和抗氧化活性进行测定。【结果】采集菌株经形态鉴定和分子鉴定,为痂状炭角菌。液体发酵最佳碳源为可溶性淀粉,最佳氮源为蚕蛹粉,最佳无机盐为MgSO₄。正交试验筛选的最佳液体培养基组成为可溶性淀粉4%（w）+蚕蛹粉0.6%（w）+MgSO₄ 0.06%（w）。固体培养基中添加缬氨酸、异亮氨酸和苏氨酸均能显著促进无性子座的生长。液体发酵产物抗菌效果显著优于山梨酸钾,对DPPH的抗氧化活性为（75.19±2.08）%,显著优于维生素E。【结论】优化的液体发酵和固体培养条件可以显著提高痂状炭角菌菌丝体产量,促进无性子座生长。痂状炭...