Changes in the upper limits of tree species distribution in the Western Caucasus (Belaya River basin) related to recent climate warming

To estimate the response of tree vegetation to recent climate warming in the Western Caucasus, the population state of several tree species at the upper limit of their distribution has been estimated in three mountain massifs in the Belaya River basin. For this purpose, the average and maximum stem diameters, vitality, and age of trees have been determined in the transitional zone between middle-mountain and high-mountain beech-fir forests (1400–1700 m a.s.l.) and in crooked birch forests growing at the upper timberline (1810–2025 m). The upper limits of Acer platanoides, A. pseudoplatanus, Ulmus glabra, and Betula litwinowii have shown a tendency to rise. The upper limit of Abies nordmanniana has remained unchanged over the past few decades, which may be explained by a decrease in moisture supply during the warm season.     

The Northern Mole Vole: Is It a Hibernator?

Based on the results of long-term field studies (1980–1997) and published data on the ecology of the northern mole vole (Ellobius talpinusPall.), it is assumed that these animals living in the Southern Urals and the Transural region do hibernate. The factors that cause their hibernation (freezing of the ground, the resultant unavailability of food, and hypoxia), some indirect evidence for hibernation (the cessation of tooth root growth from autumn to spring and a long life span), and characteristic signs of the preparation for hibernation (a decrease in body weight and an increase in liver weight) are considered. A hypothetical scheme of the active and dormant periods is proposed.     

Direct and Indirect Effects of Socioeconomic Factors on Age at First Marriage in Slum Areas,Bangladesh

This article attempts to examine the influence of some selected predictor variables on female age at first marriage in slum areas of Bangladesh. A path and multiple classification analysis (MCA) approach have been adopted. Authors thought that respondent’s educational level and the mass media such as watching television have a significant direct impact on age at marriage, while the types of family and occupational status have an indirect effect on age at marriage.     

不同退耕年限条件下菜子湖湿地土壤理化性质变化

退耕还湖是我国长江中下游地区湿地生态恢复的重要举措.土壤理化性质指标是评价湿地生态恢复状况的重要组成部分.选取菜子湖区不同退耕年限(2、5、8、10和20 a)湿地为研究对象,通过与相邻仍耕作油菜地和原始湿地土壤理化性质的比较,揭示了退耕还湖后湿地土壤生态特征变化规律.结果表明,随着退耕年限的增加,不同土壤理化性质指标变化趋势存在差异;土壤有机质含量逐年增加;土壤全氮和碱解氮含量在退耕5 a时显著升高,而后期变化平缓;土壤全磷和有效磷含量均呈先降低后升高趋势;土壤黏粒含量逐渐增加;土壤容重呈先升高后降低趋势;土壤含水量不断增加;土壤pH值缓慢降低.退耕2 a湿地土壤生态特征仍与油菜地相似,退耕2 a后土壤生态特征开始向原始湿地方向演化.退耕20 a期间湿地表层土壤理化性质变化强烈,而亚表层变化相对平缓.回归分析表明,除土壤pH和氮素含量的回归曲线拟合不显著外,退耕湿地表层土壤黏粒含量、容重、含水量、有机质含量、全磷含量和有效磷含量恢复到原始湿地水平所需时间分别为19、23、31、26、27和22 a,快于亚表层土壤的20、31、51、40、30和23 a.     

Soil physicochemical properties of Pinus tabuliformis plantations of different ages in Yanqing,Beijing北大核心CSCD

Soil physicochemical properties are important parameters to characterize soil quality. To evaluate the effects of different stand ages from young to mature on the soil physicochemical properties of Pinus tabulaeformis plantations, four different aged P. tabulaeformis plantations (14, 28, 36, and 51-year old) were investigated in Yanqing district, Beijing, China. Soil samples were collected at depths of 0-10, 10-20, and 20-30 cm, to analyze the effect of soil depth on soil physicochemical indexes. With increasing soil depth, the soil moisture content, water holding capacity, and porosity decreased gradually, but pH value increased. There was no significant difference in soil bulk density (BD) between different soil depths. Organic matter (OM), nitrogen (N), phosphorus (P), and potassium (K) content also decreased gradually with increasing soil depth, but there was no uniform change in electrical conductivity (EC). With the growth and development of P. tabulaeformis plantations, the soil moisture content, water holding capacity, and porosity of the same depth increased gradually, but pH value decreased. The difference in BD between different ages was not significant. The OM, N, and P content showed an increasing trend with increasing stand age. The K content in 14 a and 28 a plantations was significantly higher than that in 36 a and 51 a plantations. EC was the highest in 51 a plantations. The correlation analysis showed that there was a significant negative correlation between BD and water characteristics, porosity. There was a significant positive correlation between OM and N, P. The negative correlation between OM and pH reached a significant level at P < 0.01. OM was negatively correlated with BD, total potassium (TK, P < 0.05) and available potassium (AK, P > 0.05). Therefore, the soil physicochemical properties of P. tabulaeformis plantations improved with increasing stand age. Our results provide a theoretical basis for the management of P. tabulaeformis plantations in Beijing, such as thinning, fertilization management, and mixed forest forestation. © 2018 Science Press. All rights reserved.     

Derivated fetal haemoglobin as a marker for red cell age in the human fetus reflecting stimulated or impaired red blood cell production

We have determined whether derivated fetal haemoglobin (dHbF, consisting of glycated and acetylated HbF) can be used as a cell age marker for fetal red blood cells (RBCs). Cord blood was obtained between 19 and 39 weeks of gestation from 28 alloimmunised anaemic fetuses (23 RhD+ and 5 Kell) and from 20 non-anaemic fetuses and newborns (controls). Density gradient centrifugation was applied to 36 samples (20 RhD+, 15 controls and 1 Kell) to obtain fractions of increasing cell age. Blood samples were used for measurements of mean cellular volume (MCV), mean cell haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), pyruvate kinase activity (PK) and derivated fetal haemoglobin (dHbF) by cation-exchange HPLC. Reticulocytes were counted only in the whole blood samples. In all density gradient separated RBC fractions, the values for MCV, MCH and PK activity decreased and those of MCHC and dHbF increased with increasing density (equivalent to increasing cell age). The mean density was lower for RBCs of the anaemic RHD group (1.072±0.007 g/ml) than for the non-anaemic controls (1.077±0.005 g/ml) (p<0.05) The RBC density of the Kell sensitised fetus did not differ from those of the controls. In the control group, the values of the cell age markers in whole blood changed significantly with the gestational age, showing an increase of mean age of the erythrocyte population. The best linear relationship was found for dHbF (y=6.28+0.17*weeks; r=0.84; p<0.001). In the anaemic RhD+ fetuses, the RBC age markers did not change with gestational age; the dHbF percentages were lower, and the MCV, MCH, PK values and the reticulocyte counts were higher than in the controls (0.05<p<0.001). The dHbF values of the Kell sensitised fetuses were above (p<0.01) and the reticulocyte counts were below normal (p<0.05) for gestational age. For the anaemic fetuses, a significant number of the dHbF values (86%) and of the reticulocyte counts (78%) differed from the values of the controls (p<0.01). The dHbF percentages in RhD+ fetuses showed the best correlation with the Hb deficit, which is a measure for anaemia (r=−0.81, p<0.0001). We conclude that the percentage derivated HbF may indicate whether the RBC production is normal for gestational age. It may in that sense reflect stimulated or impaired erythropoiesis in alloimmunised haemolytic anaemia. Copyright © 2001 John Wiley & Sons, Ltd.     

不同颗粒龄的好氧颗粒污泥性能的研究

在SBR反应器中,分别以絮状活性污泥培养的好氧颗粒污泥和直接接种的已稳定运行1 a的好氧颗粒污泥为对象,对2种颗粒龄不同的颗粒污泥的形态、理化特性、对有机物降解能力以及微生物活性进行了比较研究.结果表明,小颗粒龄好氧颗粒的平均湿密度、污泥的比重和表示物理强度的完整系数(IC)分别为1.066 g.cm-3、1.013 g.cm-3和98.7%,各指标均高于大颗粒龄好氧颗粒的1.026 g.cm-3、1.010 g.cm-3和98.4%,两者的平均粒径分别为1.9 mm和2.2 mm.小颗粒龄好氧颗粒和大颗粒龄好氧颗粒的沉降速度分别为0.005～0.032 m.s-1和0.003～0.028 m.s-1,前者的SVI较低,且两体系中好氧颗粒的沉降速度均随粒径的增大而增大.两者对COD、NH4+-N的去除率都保持在90%以上和85%左右,从出水COD浓度、NH4+-N浓度和周期试验来看,小颗粒龄好氧颗粒对COD、NH4+-N的去除效果更好,两者对TP的去除率分别维持在40%～90%和32%～85%,但两者对TN的去除效果相差不大,去除率都在80%左右.同时,小颗粒龄好氧颗粒的异养菌比耗氧速率(SOURH)、亚硝酸菌比耗氧速率(SOURNH4)、硝酸菌比耗氧速率(SOURNO2)分别为26.4、14.8和11.2 mg.(h.g)-1,均大于大颗粒龄好氧颗粒的25.2、14.4和8.4 mg.(h.g)-1.综上所述,好氧颗粒污泥由于颗粒龄的不同会具有明显不同的理化性质,颗粒龄小的好氧颗粒具有更好的有机物降解能力、更高的微生物活性和更好的稳定性.     

Being trusted: How team generational age diversity promotes and undermines trust in cross‐boundary relationships

We examine how demographic context influences the trust that boundary spanners experience in their dyadic relationships with clients. Because of the salience of age as a demographic characteristic as well as the increasing prevalence of age diversity and intergenerational conflict in the workplace, we focus on team age diversity as a demographic social context that affects trust between boundary spanners and their clients. Using social categorization theory and theories of social capital, we develop and test our contextual argument that a boundary spanner's experience of being trusted is influenced by the social categorization processes that occur in dyadic interactions with a specific client and, simultaneously, by similar social categorization processes that influence the degree to which the client team as a whole serves as a cooperative resource for demographically similar versus dissimilar boundary spanner–client dyads. Using a sample of 168 senior boundary spanners from the consulting industry, we find that generational diversity among client team members from a client organization undermines the perception of being trusted within homogeneous boundary spanner–client dyads while it enhances the perception of being trusted within heterogeneous dyads. The perception of being trusted is an important aspect of cross‐boundary relationships because it influences coordination and the costs associated with coordination. © 2015 The Author Journal of Organizational Behavior Published by John Wiley & Sons Ltd     

The moderating effects of job control and selection,optimization, and compensation strategies on the age–work ability relationship

Work ability describes employees' capability to carry out their work with respect to physical and psychological job demands. This study investigated direct and interactive effects of age, job control, and the use of successful aging strategies called selection, optimization, and compensation (SOC) in predicting work ability. We assessed SOC strategies and job control by using employee self‐reports, and we measured employees' work ability using supervisor ratings. Data collected from 173 health‐care employees showed that job control was positively associated with work ability. Additionally, we found a three‐way interaction effect of age, job control, and use of SOC strategies on work ability. Specifically, the negative relationship between age and work ability was weakest for employees with high job control and high use of SOC strategies. These results suggest that the use of successful aging strategies and enhanced control at work are conducive to maintaining the work ability of aging employees. We discuss theoretical and practical implications regarding the beneficial role of the use of SOC strategies utilized by older employees and enhanced contextual resources at work for aging employees. Copyright © 2012 John Wiley & Sons, Ltd.