Carbon emissions. The economic benefits of the Kyoto Protocol

The third Conference of the Parties in Kyoto set the target of reducing greenhouse-gas emissions by an average of 5.3% with respect to 1990 values by 2008-2012. One of the main objections to the protocol's ratification is that compliance would pose an unbearable economic burden on the countries involved. But we show here that this is not the case if costs apart from the direct costs of energy production are also considered. Costs are also incurred in rectifying damage to human health, material goods, agriculture and the environment related to greenhouse-gas emissions.     

热轧机轴承系统的热平衡分析

以热连轧机轴承系统的热变形故障作为研究对象,详细分析了轴承系统的内热源和轴承摩擦力矩的两种计算方法,最后采用PALMGREN公式计算了不同转速下的轴承温升.     

Changes in calpastatin localization and expression during calpain activation: a new mechanism for the regulation of intracellular Ca<Superscript>2+</Superscript>-dependent proteolysis

The amount of calpastatin directly available in cytosol is under the control of [Ca²⁺] and [cyclic AMP]. Prolonged calpain activation also promotes degradation of calpastatin. The fluctuation of calpastatin concentration in cell soluble fraction is accompanied by an initial decrease in calpastatin gene expression, followed by a fivefold increase in its expression when the inhibitor protein is degraded. This process can be conceptualized as a mechanism to regulate calpastatin availability in the cell. This conclusion is supported by the fact that calpain, the other component of this proteolytic system, undergoes changes in its levels of expression in a much more limited manner. Furthermore, this process can be observed both in cells exposed to different natural stimuli, or in other cell lines. Modification of calpastatin gene expression might represent a new tool for the in vivo control of the regulatory machinery required for the modulation of Ca²⁺-dependent proteolysis.Received 18 July 2003; received after revision 3 September 2003; accepted 23 September 2003     

Monkeys reject unequal pay

During the evolution of cooperation it may have become critical for individuals to compare their own efforts and pay-offs with those of others. Negative reactions may occur when expectations are violated. One theory proposes that aversion to inequity can explain human cooperation within the bounds of the rational choice model, and may in fact be more inclusive than previous explanations. Although there exists substantial cultural variation in its particulars, this 'sense of fairness' is probably a human universal that has been shown to prevail in a wide variety of circumstances. However, we are not the only cooperative animals, hence inequity aversion may not be uniquely human. Many highly cooperative nonhuman species seem guided by a set of expectations about the outcome of cooperation and the division of resources. Here we demonstrate that a nonhuman primate, the brown capuchin monkey (Cebus apella), responds negatively to unequal reward distribution in exchanges with a human experimenter. Monkeys refused to participate if they witnessed a conspecific obtain a more attractive reward for equal effort, an effect amplified if the partner received such a reward without any effort at all. These reactions support an early evolutionary origin of inequity aversion.     

POT1 as a terminal transducer of TRF1 telomere length control

Human telomere maintenance is essential for the protection of chromosome ends, and changes in telomere length have been implicated in ageing and cancer. Human telomere length is regulated by the TTAGGG-repeat-binding protein TRF1 and its interacting partners tankyrase 1, TIN2 and PINX1 (refs 5-9). As the TRF1 complex binds to the duplex DNA of the telomere, it is unclear how it can affect telomerase, which acts on the single-stranded 3' telomeric overhang. Here we show that the TRF1 complex interacts with a single-stranded telomeric DNA-binding protein--protection of telomeres 1 (POT1)--and that human POT1 controls telomerase-mediated telomere elongation. The presence of POT1 on telomeres was diminished when the amount of single-stranded DNA was reduced. Furthermore, POT1 binding was regulated by the TRF1 complex in response to telomere length. A mutant form of POT1 lacking the DNA-binding domain abrogated TRF1-mediated control of telomere length, and induced rapid and extensive telomere elongation. We propose that the interaction between the TRF1 complex and POT1 affects the loading of POT1 on the single-stranded telomeric DNA, thus transmitting information about telomere length to the telomere terminus, where telomerase is regulated.     

Dual effect of cannabinoid CB<Subscript>1</Subscript> receptor stimulation on a vanilloid VR1 receptor-mediated response

Cannabinoid CB1 receptors and vanilloid VR1 receptors are co-localized to some extent in sensory neurons of the spinal cord and dorsal root ganglia. In this study, we over-expressed both receptor types in human embryonic kidney (HEK)-293 cells and investigated the effect of the CB1 agonist HU-210 on the VR1-mediated increase in intracellular Ca2+ ([Ca2+]i), a well-known response of the prototypical VR1 agonist capsaicin. After a 5-min pre-treatment, HU-210 (0.1 microM) significantly enhanced the effect of several concentrations of capsaicin on [Ca2+]i in HEK-293 cells over-expressing both rat CB1 and human VR1 (CB1-VR1-HEK cells), but not in cells over-expressing only human VR1 (VR1-HEK cells). This effect was blocked by the CB1 receptor antagonist SR141716A (0.5 microM), and by phosphoinositide-3-kinase and phospholipase C inhibitors. The endogenous agonist of CB1 and VR1 receptors, anandamide, was more efficacious in inducing a VR1-mediated stimulation of [Ca2+]i in CB1-VR1-HEK cells than in VR1-HEK cells, and part of its effect on the former cells was blocked by SR141716A (0.5 microM). Pre-treatment of CB1-VR1-HEK cells with forskolin, an adenylate cyclase activator, enhanced the capsaicin effect on [Ca2+]i. HU-210, which in the same cells inhibits forskolin-induced enhancement of cAMP levels, blocked the stimulatory effect of forskolin on capsaicin. Our data suggest that in cells co-expressing both CB1 and VR1 receptors, pre-treatment with CB1 agonists inhibits or stimulates VR1 gating by capsaicin depending on whether or not cAMP-mediated signalling has been concomitantly activated.     

Rewarding effects of opiates are absent in mice lacking the receptor for substance P

Modulation of substance P activity offers a radical new approach to the management of depression, anxiety and stress. The substance P receptor is highly expressed in areas of the brain that are implicated in these behaviours, but also in other areas such as the nucleus accumbens which mediate the motivational properties of both natural rewards such as food and of drugs of abuse such as opiates. Here we show a loss of the rewarding properties of morphine in mice with a genetic disruption of the substance P receptor. The loss was specific to morphine, as both groups of mice responded when cocaine or food were used as rewards. The physical response to opiate withdrawal was also reduced in substance P receptor knockout mice. We conclude that substance P has an important and specific role in mediating the motivational aspects of opiates and may represent a new pharmacological route for the control of drug abuse.     

非线性时间序列的最优相关维数估计

提出以能量谱中的截断频率之倒数作为相空间重构过程中的窗长，在窗长固定情况下，利用奇异值分解算法确定嵌入维数和时间延迟两个参数，克服了不考虑窗长单独选择嵌入维数和时间延迟造成的相关维数收敛性差的缺点，大大提高了计算效率。采用迭代奇异值分解算法对含噪声的信号进行降噪，降低了噪声对相关维数计算结果的影响，从而提高了计算结果的可靠性。