Temperature and acidity for maximal fluorescence of serotonin and serotonin-O.P.T.

Résumé Dans la détermination fluorimétrique de la sérotonine elle-mÊme et du complexe sérotonine-O.P.T. (o-phthaldialdéhyde) un maximum de fluorescence a été atteint pour des normalités de HCl de 3.25–3.50 et 6.25–6.50, respectivement. Pour les deux procédés, on a noté des rapports en sens inverse entre la fluorescence produite et la température de l'échantillon, pour des températures comprises entre 5 à 35 C. Entre la température ambiante (de 20 C) et 5 C, la fluorescence s'est accrue de 30% environ.     

Three for T: molecular analysis of the low voltage-activated calcium channel family

Despite the wealth of information on voltage-gated calcium channels, little is known about low voltage-activated, T-type channels. The ability of the antihypertensive drug mibefradil to selectively block T-type channels has generated much interest in their structure, physiology and pharmacology. This review covers the cloning of a new family of calcium channels, their putative structure, the electrophysiological evidence that demonstrated that these complementary DNAs encoded low voltage-activated, T-type channels, the tissue expression of these genes, and concludes with a discussion of their possible physiological roles.     

The evolution of domain arrangements in proteins and interaction networks

Proteins are composed of domains, which are conserved evolutionary units that often also correspond to functional units and can frequently be detected with reasonable reliability using computational methods. Most proteins consist of two or more domains, giving rise to a variety of combinations of domains. Another level of complexity arises because proteins themselves can form complexes with small molecules, nucleic acids and other proteins. The networks of both domain combinations and protein interactions can be conceptualised as graphs, and these graphs can be analysed conveniently by computational methods. In this review we summarise facts and hypotheses about the evolution of domains in multi-domain proteins and protein complexes, and the tools and data resources available to study them.Received 20 September 2004; received after revision 23 October 2004; accepted 1 November 2004     

Penetration barrier to sodium fluorescein and fluorescein-labelled dextrans of various molecular sizes in brain capillaries.

The permeability of the blood-brain barrier to sodium fluorescein, or fluorescein-labelled dextrans of various molecular weights, was investigated. Unlike the capillaries in both the area postrema and the eminentia mediana, the capillaries of the cerebral cortex were impermeable to all the intravenous tracer substances used.     

Use ofEscherichia coli A.T.C.C. 9637 for the asymmetric hydrolysis of amino acid derivatives

Riassunto L'azione delle acilasi presenti nelle cellule diE. coli A.T.C.C. 9637 è stata studiata utilizzando diversi substrati. Si è così trovato che alcuni cloroacetil e fenilacetil amino acidi subiscono un'idrolisi asimmetrica.     

Substance P in medullary carcinoma of the thyroid.

High levels of substance P-like immunoreactivity were demonstrated by radioimmunoassay in the plasma and tumour of a patient with a medullary carcinoma of the thyroid.     

A beautiful sea: P. A. M. Dirac's epistemology and ontology of the vacuum

This paper charts P.A.M. Dirac's development of his theory of the electron, and its radical picture of empty space as an almost-full plenum. Dirac's Quantum Electrodynamics famously accomplished more than the unification of special relativity and quantum mechanics. It also accounted for the ‘duplexity phenomena’ of spectral line splitting that we now attribute to electron spin. But the extra mathematical terms that allowed for spin were not alone, and this paper charts Dirac's struggle to ignore or account for them as a sea of strange, negative-energy, particles with positive ‘holes’. This work was not done in solitude, but rather in exchanges with Dirac's correspondence network. This social context for Dirac’s work contests his image as a lone genius, and documents a community wrestling with the ontological consequences of their work. Unification, consistency, causality, and community are common factors in explanations in the history of physics. This paper argues on the basis of materials in Dirac's archive that --- in addition --- mathematical beauty was an epistemological factor in the development of the electron and hole theory. In fact, if we believe that Dirac's beautiful mathematics captures something of the world, then there is both an epistemology and an ontology of mathematical beauty.     

Optimal sampling frequency for volatility forecast models for the Indian stock markets

This paper evaluates the performance of conditional variance models using high‐frequency data of the National Stock Index (S&P CNX NIFTY) and attempts to determine the optimal sampling frequency for the best daily volatility forecast. A linear combination of the realized volatilities calculated at two different frequencies is used as benchmark to evaluate the volatility forecasting ability of the conditional variance models (GARCH (1, 1)) at different sampling frequencies. From the analysis, it is found that sampling at 30 minutes gives the best forecast for daily volatility. The forecasting ability of these models is deteriorated, however, by the non‐normal property of mean adjusted returns, which is an assumption in conditional variance models. Nevertheless, the optimum frequency remained the same even in the case of different models (EGARCH and PARCH) and different error distribution (generalized error distribution, GED) where the error is reduced to a certain extent by incorporating the asymmetric effect on volatility. Our analysis also suggests that GARCH models with GED innovations or EGRACH and PARCH models would give better estimates of volatility with lower forecast error estimates. Copyright © 2008 John Wiley & Sons, Ltd.     

T. C. Chamberlin,Climate Change,and Cosmogony

This paper examines the life and work of T. C. Chamberlin, a prominent glacial geologist who developed an interest in interdisciplinary earth science. His work on the geological agency of the atmosphere informed his understanding of climate change and other terrestrial phenomena and led him to propose a new theory of the formation of the Earth and the solar system.Chamberlin's graduate seminar at the University of Chicago in 1896 contained all the themes that informed his research programme over the next three decades. These included the carbon dioxide theory of climate change in its relationship to diastrophism and oceanic circulation, the role of water vapour feedbacks in the climate system, and the relationship between multiple glaciations, the climate system, and the formation of the planet.     

大气污染优化控制理论的一些新进展

本文介绍了国内学者的最新研究成果，包括了大气污染优化控制理论在以下几个具体应用领域的进展：(1)工业污染源的优化布局。应用伴随方法计算目标函数的梯度以求解优化问题，给出了理论框架。进行了数值试验。(2)短期空气质量的动态控制。应用实际气象数据和污染源数据进行了优化控制数值模拟。(3)化学风险的预先评价与控制。应用伴随方法，对运动化学源进行风险评价。规划最佳运输路线；针对禁止化学武器公约中处理日本二战期间遗弃化学武器的有关问题。妥善选择化武销毁工厂的地址。以上优化控制问题，以气象预报模式和大气污染预报模式为基础，而以伴随方法和最优化算法为求解途径，数值试验表明理论的正确性和方法的高效率。新发展的理论和方法与数值模式和观测技术紧密结合，并且顺应了计算机速度和容量高速增长的趋势。从而具有广阔的应用前景。     

Remarks on the karyotype of the polypteriformes. The chromosomes ofPolypterus delhezi,P. endlicheri congicus andP. palmas

Summary The chromosomes of 3 species of bikirs (Polypterus delhezi, P. endlicheri congicus andP. palmas) were studied in somatic metaphases. The diploid number was found to be 2 n=36 in all the species and a basic morphological identity of the karyotype emerges from karyogram comparison not only in the 3 species described herein, but also in the other Polypteriformes already studied.     

The action of substance P on mesencephalic reticular and substantia nigral neurones of the rat.

Extracellular recordings were made from neurones in the mesencephalic reticular formation and substantianigra of the rat which was anaesthetized with urethane 1.5-2 g/kg i.p. Out of 44 cells tested 42 were excited by Substance P applied iontophoretically and in some cases this excitation was rapid. Evidence is presented for Substance P as a putative excitatory transmitter onto reticular and nigral neurones possibly released from primary sensory afferents.