双耳条件下超前声对人分辨滞后声强度的影响

在复杂声环境中,对声音强度的分辨是听觉系统对声音信号精确处理的重要功能之一.到目前为止,有关人对声音强度分辨的研究都是在单耳条件下进行的,然而,正常条件下人都是利用双耳感知强度和方位变化的声音.以人对声刺激强度的最小可察觉差异(just noticeable difference,JND)为强度分辨阈值的指标,观察双耳条件下超前声对人分辨滞后声强度的影响.实验在封闭声场中进行,声刺激强度和空间方位的控制是通过改变双耳平均声压(average binaural level,ABL)和双耳声压差(interaural level difference,ILD)来模拟的.实验结果表明,与安静条件下人对声刺激强度的分辨阈值相比,低强度的超前声对人分辨滞后声强度的阈值无显著影响,而中等及以上强度(ABL大于或等于40 dB)的超前声可提高人分辨滞后声强度的阈值,阈值的提高随超前声强度的增加呈单调增大的趋势.当超前声强度一定时,超前声对人分辨滞后声强度的影响随滞后声强度的增加而衰减,对分辨较高强度的滞后声的阈值影响不显著,该结果与单耳的研究结果有明显差异.实验未发现超前声和滞后声ILD的相对改变对人探测滞后声强度变化的阈值有显著影响.     

Soil microbial diversity and soil functioning affect competition among grasses in experimental microcosms

A gradient of microbial diversity in soil was established by inoculating pasteurized soil with microbial populations of different complexity, which were obtained by a combination of soil fumigation and filtering techniques. Four different soil diversity treatments were planted with six different grass species either in monoculture or in polyculture to test how changes of general microbial functions, such as catabolic diversity and nutrient recycling efficiency would affect the performance of the plant communities. Relatively harsh soil treatments were necessary to elicit visible effects on major soil processes such as decomposition and nitrogen cycling due to the high redundancy and resilience of soil microbial communities. The strongest effects of soil diversity manipulations on plant growth occurred in polycultures where interspecific competition between plants was high. In polycultures, soil diversity reduction led to a gradual, linear decline in biomass production of one subordinate grass species (Bromus hordeaceus), which was compensated by increased growth of two intermediate competitors (Aegilops geniculata, B. madritensis). This negative covariance in growth of competing grass species smoothed the effects of soil diversity manipulations at the plant community level. As a result, total shoot biomass production remained constant. Apparently the effects of soil diversity manipulations were buffered because functional redundancy at both, the microbial and the plant community level complemented each other. The results further suggests that small trade-offs in plant fitness due to general functional shifts at the microbial level can be significant for the outcome of competition in plant communities and thus diversity at much larger scales.     

慈竹构件和分株水平总黄酮含量的变化

黄酮类化合物是植物体内重要的次生代谢物质之一。本文采用AlCl3 比色法测定了慈竹构件和分株水平总黄酮含量的变化 ,以探讨其生理生态适应性。结果表明 ,在地上 3个构件中 ,叶的总黄酮含量显著大于枝和秆 ;1龄分株叶的总黄酮含量显著大于其它 4个龄级 ,而枝和秆的含量在 5个年龄间无显著差异 ;分株上层叶和枝条的总黄酮含量显著多于中下两层的相应构件。叶龄对慈竹叶总黄酮含量有显著的影响 ,1龄、 7龄和 9龄叶片的总黄酮含量明显高于其它 6个龄级 ,但是叶龄和总黄酮含量之间无显著线性相关。同时 ,叶总黄酮含量对季节的变化敏感 ,2、 4和 12月含量最高 ,5月和 8月含量最低。在分株水平 ,1龄分株的总黄酮含量显著大于其它 4个龄级。这些结果说明慈竹的总黄酮含量对环境变化具有可塑性 ,分株水平与叶构件水平总黄酮含量对分株年龄的反应格恐相同。     

臭冷杉生物量分配格局及异速生长模型

摘 要：臭冷杉是长白山阔叶红松林中重要针叶树种,采用整株收获法分析21株臭冷杉地上地下生物量分配格局。在枝条水平上采用样枝直径（BD）、样枝长度（BL）、样枝所在轮生枝位置（WP）建立活枝、针叶生物量异速生长模型,在植株水平上采用胸径（DBH）、树高（H）、年龄（Age）、树冠长度（CL）、树冠比率（CR）、南北向冠幅（CW1）、东西向冠幅（CW2）等变量建立树干木质、树皮、活枝、针叶、粗根及整株生物量模型。并利用逐步线性回归法获得不同器官生物量最优模型。结果表明：（1）活枝生物量主要集中在树冠中下层,针叶生物量集中在树冠中层。树冠中层和下层枝叶生物量无显著差异（p>0.05）;（2）21株臭冷杉地上生物量和地下生物量变动范围分别为1.026–506.047 kg/株和0.241–112.000 kg/株。粗根、活枝、针叶、树干木质、树皮及枯枝生物量占整株生物量的相对比例分别为18.68%、18.39%、12.02%、39.29%、8.70%和2.92%;（3）地上生物量与地下生物量呈显著线性相关（p<0.001）,拟合线性方程斜率为0.23;（4）枝条水平上,活枝生物量模型解释量超过95%,平均预测误差小于30%。与单变量（BD）活枝生物量模型相比,2变量（BD、BL）和3变量（BD、BL、WP）模型解释量分别提高1.2%和2.0%,平均预测误差分别下降6.26%和9.27%。针叶生物量相对较难预测,模型解释量仅为82.7%,平均预测误差接近50%,模型中增加BL 和WP变量并未提高针叶生物量的预测精度。活枝生物量与BD、BL、WP正相关,针叶生物量与BD正相关,与BL、WP负相关;（5）植株水平上,基于胸径的单变量模型可解释量大于90%,增加树高变量未能显著提高生物量模型的预测精度。年龄决定了臭冷杉的树干生物量,忽视年龄变量将会产生生物量预测误差。树冠特征是影响枝叶生物量预测精度的重要变量。综合考虑模型的可解释量及回归系数显著性可知,胸径是预测臭冷杉不同器官生物量的可靠变量。     

Estimation of economic injury level of Aphis craccivora Koch. (Homoptera: Aphididae) infesting faba bean in new reclaimed area

This work was based on field screening procedure to detect the population density of Aphis craccivora for two successive seasons (2004–2005) and (2005–2006) to emphasis the relation between the economic injury level (EIL) and yield loss.

Results obtained showed that the equilibrium position (steady point) during the first and second season was 9.06 and 3.32 individuals/five leaflets, respectively, while the injury level was 3.4 and 1.16 individuals/leaflets. When the bean plant was subjected to three successive insecticidal applications during the early growing, season is sufficient to decrease the yield loss significantly (yield capacity 21.43 Ard./fed.) with comparing to untreated plant (14.98 Ard./fed.), while the plants exposure for one treatment was 17.36 Ard./fed. The EIL was 8.6 individual of aphids/plant depending on the market price of bean and control cost during the season.     

Obesity Level and Attrition: Support for Patient-Treatment Matching in Obesity Treatment

Obesity treatment studies report attrition rates front 20% to 45%. To reduce attrition, researchers have proposed matching patients to treatment based upon level of obesity. The current study attempted to validate the commonly held assumption that a mismatch between obesity level and treatment will promote attrition. The level of obesity and attrition rates of 39 adults who enrolled in a 12-session behavior therapy program were examined. As obesity level increased, so did attrition. Sixty-nine percent of subjects with mild obesity, 43% of subjects with moderate obesity and 0% of subjects with severe obesity completed treatment.     

Seed banks of grazed and ungrazed Baltic seashore meadows

Abstract. The seed banks of three grazed and three ungrazed seashore meadows were studied on the west coast of Finland. 8486 seedlings (mean 13 669 seedlings/m²) germinated from cold-treated samples (n = 343; depth = 10 cm). Most seedlings and species were monocots and perennials. The seed bank flora included 54 dicots vs. 28 monocots and 66 perennials vs. 16 annuals. The most abundant species were Juncus gerardii, Schoenoplectus tabernaemontani, Eleocharis uniglumis, Agrostis stolonifera, Juncus bufonius and Carex nigra, which made up 73% of the seed bank. Numbers of species and seedlings differed between elevation classes. Species richness was highest in elevation class 50–70 cm. The highest seed density occurred in class 20–50 cm. A model for size and species composition of the seed bank in relation to elevation is presented. The seed bank was larger and richer in species in the ungrazed than in the grazed sites, but not so in the upper elevations and closest to the open sea. Grazing reduced the size of the seed bank of Agrostis stolonifera, A. capillaris, Calamagrostis stricta, Elymus repens, Juncus bufonius, Limosella aquatica and Schoenoplectus tabernaemontani, but increased that of J. gerardii. 32 species germinated only from ungrazed samples and 11 species only from grazed ones. Multivariate classification resulted in nine sample groups. The ordination scatter was best explained by the flooding stress variables, elevation, the distance from the water line and the number of helophyte species in samples. 75 species were found both in the seed bank and in the vegetation, but there was a significant lack of resemblance (in the Mantel test) due to over-representation of some species. Eight species occurring only in the seed bank were mainly annuals or biennials (63%); those occurring only in the established vegetation (86 species) were mainly perennials (86%).     

女性受教育程度与其生育水平关系的数学模型分析

本文对我国女性受教育程度与其活产子女数、总和孩次递比等重要的生育水平指标间的关系进行了全面而深入的统计分析，并得到反映其定量关系的回归方程数学模型，从而揭示出女性受教育程度对其生育水平所具有的重大作用。     

Tackling codon usage bias for heterologous expression in Rhodobacter sphaeroides by supplementation of rare tRNAs

The photosynthetic Rhodobacter species are promising alternative expression hosts in bioproduction and biorefinery due to their unique metabolic capacities. With prominent inner membrane areas and efficient endogenous translocation machineries, they are especially attractive for membrane protein expression. However, codon usage bias could be a limitation in the engineering of Rhodobacter species and has seldom been investigated. In this study, we tackled the codon bias of Rhodobacter by functionally expressing 8 rare tRNAs of Rhodobacter sphaeroides with a multi-copy vector. The impact of tRNA supplementation was evaluated through monitoring expression levels of two heterologous proteins with different phylogenetic origins, a membrane subunit of the riboflavin transporter, RibU, from Lactobacillus acidophilus La-14 and a decaheme cytochrome, MtrA, from Shewanella oneidensis. Our results showed that the performances were closely related to medium composition and rare codon percentages of raw DNA sequences. Provision of rare tRNAs has increased RibU production by 7.7-folds and 2.86-fold in minimal medium and rich medium, respectively, while MtrA levels were increased by 1-fold in minimal medium. The present study confirms the presence of codon bias in R. sphaeroides and offers a facile tool for improving heterologous expression of rare-codon containing genes. We anticipate that this tRNA supplementation system can be further extended to other species of Rhodobacter, and thus will facilitate the engineering of purple bacteria for interesting applications in microbial technology.     

Immune responses in normal Indian langur monkeys (Presbytis entellus)--a primate model for visceral leishmaniasis

Abstract: The Indian langur monkey (Presbytis entellus) is an experimental host for a range of human diseases and for the assessment of vaccine candidate antigens to some common parasitic infections. This experimental host is particularly suitable for the follow‐up of immunological responses. To understand some of the mechanism that underlies the defense against experimental pathogens there is a need of the basic knowledge on antibody and cell mediated immune responses. In the present study 25 naïve monkeys were subjected to for assessment of their antibody responses to various human parasitic antigens as well as mitogen induced cellular responses. Only few monkeys were found to have low titer of antiparasitic antibodies. There was compressive dose dependent proliferative response of peripheral blood mononuclear cells. Unlike humans, the blastogenic as well as cytokine responses (IFN‐γ, IL‐2 and IL‐4) to Con A was considerably higher as compared to PHA. These findings are similar to what have been reported in other non‐human primates, confirming the appropriateness of Indian langurs for pre‐clinical trials.     

黄土高原典型草原地上生物量估测模型

为了寻求有效的草地地上生物量估测方法和精确估测黄土高原典型草原草原地上生物量。于2014年8月中旬,在黄土高原典型草原草原地上生物量达到最大值,分别从单株水平和种群水平进行野外调查。以株高(H)和盖度(C)的复合因子(C×H)为自变量,通过回归分析,建立地上生物量估测模型,采用留一法对其精确性进行评估;并通过校正系数以及群落总生物量估测值和实测值比较单株水平和种群水平所建模型的精确性。结果表明:黄土高原典型草原草地,无论在单株水平还是种群水平,线性和幂函数对该区域生物量的拟合效果更好。估测模型检验结果表明,在单株水平各个物种的生物量估测值与实测值相关性较好,均达到了显著水平(P0.05),其r值均大于0.6,总相对误差RS均小于10%,平均相对误差绝对值RMA(average absolute value of relative error)均小于30%,总生物量的实测值与估测值比较接近,校正系数均接近1;而在种群水平上,虽然各物种的生物量估测值与实测值相关性均达到了显著水平(P0.05),但多数物种平均相对误差绝对值RMA大于30%,总相对误差RS(total relative error)均大于10%,总生物量的估测值均大于实测值,校正系数均偏离了1,说明在黄土高原典型草原通过单株水平建立的物种生物量估测模型的精度优于种群水平建立的物种生物量估测模型的精度。     

基于水质管理目标的博斯腾湖生态水位研究

人类开发活动导致湖泊生态功能严重退化,研究湖泊生态水位对于维持湖泊生态系统健康意义重大。针对博斯腾湖化学需氧量(COD)浓度较高的水环境现状,分析博斯腾湖水位和COD浓度关系,研究提出基于水质管理目标的生态水位,以期为博斯腾湖水资源、水环境管理提供参考。结果表明,博斯腾湖水位与水体COD浓度显著负相关,但由于COD浓度空间差异较大以及影响因素不唯一,水位与COD浓度两者之间曲线估计结果不理想。为实现博斯腾湖COD浓度小于20 mg/L的水质管理目标,引入累计水位概念进行统计分析得到两个特征水位:所有COD浓度大于等于20 mg/L的数据对应水位的平均值为1046.02 m,该水位在历史丰水期水位的频率为60.83%,可作为最小生态水位;所有COD`浓度小于等于20 mg/L的数据对应水位的平均值为1046.4 m,该水位在历史丰水期水位的频率为44.70%,可作为适宜生态水位。适宜生态水位1046.4 m与已有研究成果基本相符,博斯腾湖在1046.4 m时既有利于水质管理,也可保障湖泊整体生态系统健康。     

饲料中不同蛋白、脂肪水平对春鲤生长、饲料利用和体成分的影响

研究旨在探讨洱海土著鱼类春鲤(Cyprinus longipectoralis)(初始体重0.55 g)对蛋白质和脂肪的需求量。实验采用3×3双因子设计,蛋白水平为33%、39%和45%,脂肪水平为5%、8%和11%,共9组等能饲料。实验在水温为(28±2)℃的室内微流水系统中进行,为期56d。实验结果表明:随着蛋白水平的提高,摄食率显著降低(P<0.05),饲料效率、能量沉积率、鱼体水分和脂肪含量显著升高(P<0.05),但特定生长率、蛋白质效率、蛋白沉积率、鱼体灰分含量和能值均无显著变化(P>0.05)。随着脂肪水平的提高,特定生长率、蛋白沉积率和鱼体蛋白含量显著下降,鱼体脂肪含量显著上升(P<0.05),而摄食率、饲料效率、能量沉积率、鱼体水分和灰分含量以及能值则无明显变化(P>0.05)。通过折线回归分析得出,当饲料中蛋脂比为7.30时,春鲤有最大的特定生长率。研究结果表明,春鲤饲料中适宜的蛋白和脂肪水平分别为33%—34%和4%—5%。     

摩天岭北坡森林木本植物叶性状在物种和群落水平沿海拔梯度的变化

该研究采用样线和样地相结合的方法,对甘肃省白水江国家级自然保护区摩天岭北坡大垭子梁森林不同海拔(1 600~2 100m)的植物群落进行野外调查、采样分析,并运用线性回归分析、Pearson相关性分析及曲线拟合分析方法,研究木本植物的比叶面积(SLA)、叶干物质含量(LDMC)、叶碳氮磷含量(LCC、LNC、LPC)及其计量比(C/N、C/P、N/P)等叶性状变化特征,以及在物种和群落水平随海拔梯度的变化趋势和相关性。结果表明:(1)摩天岭北坡大垭子梁山地森林为落叶阔叶林带,共有木本植物13科23种,其中乔木6种,灌木17种,且整体上灌木种类较为丰富。此外,有些物种在不同海拔间都有分布,如华北落叶松(Larix principis-rupprechtii)、胡枝子(Lespedeza bicolor)等,反映出不同植物对于异质环境的适应。(2)8个叶功能性状中变异系数最小的是LCC(4.6%),属于弱变异,最大的是SLA(42.1%),其他叶性状都属于中等变异,表明在其他叶性状的协同作用下,使得木本植物的碳获取保持在一定的水平以确保群落的稳定性。(3)叶片功能性状间的关联性普遍存在,是植物适应环境的一种对策.该研究表明SLA-LNC以及LNC-LPC在物种和群落水平上的相关性及其相关程度均一致,而其他叶性状间相关关系则有所不同,这为以后进行大尺度研究时对叶性状的选择提供了一定的依据。(4)叶性状随海拔的变化趋势,除C/N和N/P在物种和群落水平上变化趋势不一致外,其他各个性状随海拔的总体变化趋势基本一致,但显著程度只有LNC一致外其他均不同,反映了木本植物的不同叶片功能性状对海拔造成的不同环境的适应。     

Counting by weighing and its effect on seed testing procedures

Counting by weighing is an approximate procedure for obtaining a given number of items based on an estimate of how much the items will weigh. The procedure can be considerably faster than exact counting. We show how the effects of counting by weighing can be assessed, using a particular problem in seed testing for illustration. We find that using counting by weighing in place of exact counting has little effect on the outcome of the seed test provided that the coefficient of variation of the individual seed weights is not too large, and provided a sufficiently large initial sample is used to estimate mean seed weight.     

Ecdysteroid levels and developmental events during larval moulting in the silkworm, Bombyx mori

In the silkworm, Bombyx mori, apolysis of the spiracle is the first visible sign of the initiation of a larval moult. After spiracular apolysis, the characteristic sequence of new spiracle formation can be recognized easily through the cuticle around the old spiracle. This sequence, called the spiracle index, was used as the basis for a precise developmental chronology of the larval moulting period. At certain spiracle-index stages, histological changes in the larval ventral abdominal integument were also examined. By allatectomy and abdominal ligations, the critical periods for the secretion of juvenile hormone and ecdysone respectively were found to be at the initiation of spiracular apolysis and at the time when general apolysis was complete. The haemolymph-ecdysteroid level as measured by radioimmunoassay was about 30–50 ng/ml during the first 2 days of the 4th instar, 60–70 ng/ml at the time of initiation of spiracular apolysis, and 200 ng/ml at the time of completion of apolysis of the general body surface. The maximal level of the hormone was about 290 ng/ml at the mid-moulting period. The relationship between the ecdysteroid titre and morphological events occurring during the larval moult was discussed.     

湖泊水位变动对水生植被的影响机理及其调控方法

水位的高低及其变动范围、频率、发生的时间、持续的时长和规律性等是影响湖泊水生植被的核心因子.水位变动有短期、年内季节性和年际变动3种,对湖泊水生植被有不同的影响机理.水位短期变动通过对水体中的悬浮物、透明度、光衰减系数等的影响而对水生植被产生作用;周期性的年内季节性和年际水位变动可对水生植被的生态适宜性产生影响,并进而改变其时空分布;长期的高水位和低水位以及非周期性的水位季节变动会破坏水生植被长期以来对水位周期性变化所产生的适应性,从而影响了植被的正常生长、繁衍和演替.植被的极端深度和物种多样性是水位调控的核心表征指标,可通过经验数据分析法、生态模型法和参照法等方法来确定湖泊的适宜水位变动范围和时间.研究对象选择、研究方法、管理中的应用以及重要环境变化所产生的影响等是今后相关研究的核心问题.     

Design characteristics of worksite environmental interventions for obesity prevention

Objective: This paper describes the design characteristics of the National Heart, Lung, and Blood Institute (NHLBI)‐funded studies that are testing innovative environmental interventions for weight control and obesity prevention at worksites. Research Methods and Procedures: Seven separate studies that have a total of 114 worksites (～48,000 employees) across studies are being conducted. The worksite settings include hotels, hospitals, manufacturing facilities, businesses, schools, and bus garages located across the U.S. Each study uses its own conceptual model drawn from the literature and includes the socio‐ecological model for health promotion, the epidemiological triad, and those integrating organizational and social contexts. The interventions, which are offered to all employees, include environmental‐ and individual‐level approaches to improve physical activity and promote healthful eating practices. Environmental strategies include reducing portion sizes, modifying cafeteria recipes to lower their fat contents, and increasing the accessibility of fitness equipment at the workplace. Across all seven studies about 48% (N = 23,000) of the population is randomly selected for measurements. The primary outcome measure is change in BMI or body weight after two years of intervention. Secondary measures include waist circumference, objective, and self‐report measures of physical activity, dietary intake, changes in vending machines and cafeteria food offerings, work productivity, healthcare use, and return on investment. Discussion: The results of these studies could have important implications for the design and implementation of worksite overweight and obesity control programs.     

施氮对不同有机碳水平桉树林土壤微生物群落碳代谢的影响

土壤微生物群落碳代谢功能既受土壤氮素水平的影响,也与土壤有机碳水平密切相关,但二者如何共同影响土壤微生物群落碳代谢功能的研究尚不多见。以我国南方广泛种植的桉树林为对象,采用野外控制实验比较研究了4种施氮处理(对照:0kg/hm2,低氮:84.2 kg/hm2,中氮:166.8 kg/hm2,高氮:333.7 kg/hm2)对有机碳水平差异显著的两桉树林样地土壤微生物群落碳代谢功能的影响,结果表明:(1)两种有机碳水平桉树林土壤微生物群落碳代谢强度和代谢碳源丰富度显著不同,高有机碳水平桉树林土壤微生物群落碳代谢强度和代谢碳源丰富度显著高于低有机碳水平桉树林(P0.01);(2)施氮显著改变了桉树林土壤微生物群落的碳代谢强度和代谢碳源丰富度(P0.05),随着施氮水平的升高,土壤微生物群落碳代谢强度和代谢碳源丰富度均呈现先增加后降低的变化规律,但是高、低有机碳水平桉树林土壤微生物群落碳代谢强度和代谢碳源丰富度对施氮梯度的响应各不相同,高、低有机碳水平桉树林的土壤微生物群落碳代谢指标分别在中氮、低氮处理中达到最高值;(3)施氮影响土壤微生物群落代谢的碳源类型主要是碳水化合物类、氨基酸类和羧酸类,土壤微生物生物量是影响土壤微生物碳代谢强度和代谢碳源丰富度的重要因素。由此可知,施氮对土壤微生物碳代谢功能影响,也与土壤本底中有机碳水平的调节有关,所以在研究土壤微生物群落对施氮等条件的响应时,不能忽略土壤中有机碳水平。     

Diversity and host associations of dipteran insects exploiting fungal fruiting bodies in Hokuriku,central Japan

To clarify the diversity and host associations of dipteran insects exploiting fungal fruiting bodies, we collected fruiting bodies at 18 localities in Hokuriku region, central Japan, from 2012 to 2015 and examined them for the emergence of insects. In total, 14,107 dipteran individuals belonging to 20 families emerged from fungi of 8 orders, 25 families, 49 genera and 129 species. Approximately 79% of dipteran individuals belonged to three families, Phoridae, Muscidae and Drosophilidae. The faunal similarity at the family level was relatively high between central (warm‐temperate) and northern (cool‐temperate) areas of Japan. However, the species composition of Drosophilidae was much different between central and northern Japan. The difference in the species composition was discussed in relation to the climatic conditions and fungal flora. None of the species from Drosophilidae, Phoridae, Muscidae, Mycetophilidae, Lonchaeidae and Chloropidae were specialists (they exploited more than one species of fungi), but they showed differences their fungi preference. Adults of some families, especially Drosophilidae, were frequently collected from fruiting bodies, but those of other families were seldom collected, probably reflecting differences in adult feeding ecology.