Urban Metabolism and the Energy Stored in Cities

Using the city of Toronto as a case study, this article examines impacts of energy stocks and flexible demand in the urban metabolism on the resilience of the city, including discussion of directions for further study of the resiliency of the urban metabolism. An important element developed is the nominal residence time of the energy stocks. This value defines how long an energy stock lasts under typical patterns of energy use. The findings suggest that the residence times of many sources of energy overcome vulnerability when energy supply shocks last on the order of hours or a few days, but that the measure is limited to assessing only certain types of commonly used energy sources in aggregate terms. Discussion is included on the uncertainty of this measure and on the metabolic and resiliency implications of new technologies intended to reduce energy use and improve sustainability of cities and the use of the urban metabolism as a means of comparison. The methodology employed highlights how waste energy could be used to increase the resiliency of the city's water supply, but also how the study of the urban metabolism would benefit from a more disaggregate form in the study of sustainable and resilient cities.     

Elastase is a constituent product of T cells

Proteases produced by immune cells have been found to be important components of the immune response to antigen. A protease previously unrecognized as a specific T cell product has been identified which has the gene sequence, serologic crossreactivity, and enzymatic specificity of elastase. T cell elastase, found in combination with the natural elastase inhibitor alpha 1-antitrypsin (alpha 1-protease inhibitor, alpha 1-PI), is produced by both CD4+ and CD8+ T lymphocytes, and is found both in a membrane-bound and in a soluble form in murine T cell lines.     

Analysis of therapeutic growth hormone preparations: report of an interlaboratory collaborative study on growth hormone assay methodologies.

Recombinant DNA-derived human growth hormone (somatotropin) is widely used to treat growth hormone-deficient children. The potency of this product is determined by in-vivo bioassay in hypophysectomized rats, which is imprecise, costly and invasive, and there have been suggestions that it could safely be replaced with in-vitro or physico-chemical alternatives. In this report we present the results of a collaborative study designed to test this proposal. Somatotropin was modified by mild or severe proteolysis, mild or severe oxidation or treatment at high pH, and compared in a multi-centre collaborative study with unmodified somatotropin or with dimerized somatotropin. Participating laboratories included manufacturers and national control laboratories, and pharmacopoeial bioassays were compared with in-house in-vitro and physico-chemical bioassays. Although performing adequately with untreated somatotropin, for degraded samples the in-vivo bioassays were relatively unresponsive to changes in the growth hormone molecule. In contrast, the physico-chemical assays, in particular the reverse-phase HPLC, performed with a high degree of selectivity. We conclude that in the case of somatotropin, the in-vivo bioassay can be removed from the routine product specification with an acceptable degree of security. This however does not obviate the requirement rigorously to demonstrate biological activity in-vivo during product development, nor may the conclusions of this study be applied to other therapeutic recombinant proteins without similar collaborative investigations.     

新疆塔里木柯坪地区上奥陶统凯迪阶串管海绵类化石及其滤食选择性探讨北大核心

奥陶纪是串管海绵早期演化的一个关键阶段,记录了该类群的首次大规模辐射演化事件(属级分类单元达15个)。然而,现有大部分奥陶系串管海绵的报道来自澳大利亚东部和北美等地,在中国至今仅发现了两个属,与前述地区相比研究程度偏低。早期研究主要基于形态学特征对串管海绵进行系统分类描述,对其滤食策略知之甚少,因此制约了对此类海绵在奥陶纪底栖生态系统作用的相关探讨。本文系新疆塔里木柯坪地区奥陶纪串管海绵的首次系统古生物学报道,详细描述凯迪阶(上奥陶统)印干组中保存完好的阔室丛花海绵(Corymbospongia amplia)化石的形态学特征,并通过研究标本外壁微孔孔径的大小分布,探讨其滤食选择性。海绵外壁微孔孔径的分析表明:小型和微型浮游生物可能是其食物的主要来源,而多细胞浮游动物因个体尺寸大于海绵外壁微孔,不能被阔室丛花海绵捕获。本研究为奥陶纪串管海绵古生态学及其地球生物学意义的探讨提供了进一步的依据。     

THE ROLE OF ROOTS IN THE NUTRITION OF AQUATIC VASCULAR PLANTS

Rooted stems of three aquatic species were cultured in a two-compartment apparatus which allowed the upper and lower portions of the stem to be kept in different nutrient solutions. P³² was supplied to either the upper or lower compartment. At the end of a 10-day growth period, the specific activity of phosphate was determined in axillary shoots which developed during the course of the experiment from buds in the upper compartment. The results indicated that most of the phosphate in these shoots was not absorbed from the ambient medium but was derived from the rooted stem base in the lower compartment (over 90 % in Myriophyllum brasiliense, 59 % in M. spicatum, and 74 % in Elodea densa). These results give a very different but probably more accurate picture of phosphate absorption in rooted aquatic vascular plants than short-term experiments, in which phosphate is readily taken up from the ambient medium by leaves of M. spicatum and E. densa. In M. brasiliense the amount of phosphate translocated is related to the mass of roots present. Evidence is presented that normal growth of axillary shoots occurs even when all mineral ions have to be obtained by translocation from the lower compartment.