Reshuffling the OPE: Delocalized Operator Expansion

A generalization of the operator product expansion for Euclidean correlators of gauge invariant QCD currents is presented. Each contribution to the modified expansion, which is based on a delocalized multipole expansion of a perturbatively determined coefficient function, sums up an infinite series of local operators. On a more formal level the delocalized operator expansion corresponds to an optimal choice of basis sets in the dual spaces which are associated with the interplay of perturbative and nonperturbative N-point correlations in a distorted vacuum. A consequence of the delocalized expansion is the running of condensates with the external momentum. Phenomenological evidence is gathered that the gluon condensate, often being the leading nonperturbative parameter in the OPE, is indeed a function of resolution. Within a model calculation of the nonperturbative corrections to the ground state energy of a heavy quarkonium system it is shown exemplarily that the convergence properties are better than those of the OPE. Potential applications of the delocalized operator expansion in view of estimates of the violation of local quark-hadron duality are discussed.Comment: Talk given at conference Continuous advances in QCD 2002 / Arkadyfest, Minneapolis; 16 pages, 4 figure

Mathematics, Thermodynamics, and Modeling to Address Ten Common Misconceptions about Protein Structure, Folding, and Stability

To fully understand the roles proteins play in cellular processes, students need to grasp complex ideas about protein structure, folding, and stability. Our current understanding of these topics is based on mathematical models and experimental data. However, protein structure, folding, and stability are often introduced as descriptive, qualitative phenomena in undergraduate classes. In the process of learning about these topics, students often form incorrect ideas. For example, by learning about protein folding in the context of protein synthesis, students may come to an incorrect conclusion that once synthesized on the ribosome, a protein spends its entire cellular life time in its fully folded native confirmation. This is clearly not true; proteins are dynamic structures that undergo both local fluctuations and global unfolding events. To prevent and address such misconceptions, basic concepts of protein science can be introduced in the context of simple mathematical models and hands-on explorations of publicly available data sets. Ten common misconceptions about proteins are presented, along with suggestions for using equations, models, sequence, structure, and thermodynamic data to help students gain a deeper understanding of basic concepts relating to protein structure, folding, and stability

Lactation Defect in a Widely Used MMTV-Cre Transgenic Line of Mice

MMTV-Cre mouse lines have played important roles in our understanding about the functions of numerous genes in mouse mammary epithelial cells during mammary gland development and tumorigenesis. However, numerous studies have not included MMTV-Cre mice as controls, and many investigators have not indicated which of the different MMTV-Cre founder lines were used in their studies. Here, we describe a lactation defect that severely limits the use of one of the most commonly used MMTV-Cre founder lines.To explore the role of protein tyrosine phosphatase Shp1 in mammary gland development, mice bearing the floxed Shp1 gene were crossed with MMTV-Cre mice and mammary gland development was examined by histological and biochemical techniques, while lactation competency was assessed by monitoring pup growth. Surprisingly, both the Shp1fl/+;MMTV-Cre and MMTV-Cre female mice displayed a severe lactation defect when compared to the Shp1 fl/+ control mice. Histological and biochemical analyses reveal that female mice expressing the MMTV-Cre transgene, either alone or in combination with floxed genes, exhibit defects in lobuloalveolar expansion, presence of large cytoplasmic lipid droplets in luminal alveolar epithelial cells postpartum, and precocious induction of involution. Using a PCR-based genotyping method, the three different founder lines can be distinguished, and we determined that the MMTV-Cre line A, the most widely used MMTV-Cre founder line, exhibits a profound lactation defect that limits its use in studies on mammary gland development.The identification of a lactation defect in the MMTV-Cre line A mice indicates that investigators must use MMTV-Cre alone mice as control in studies that utilize Cre recombinase to excise genes of interest from mammary epithelial cells. Our results also suggest that previous results obtained in studies using the MMTV-Cre line A line should be re-evaluated if the controls did not include mice expressing only Cre recombinase

Острые отравления диацетилморфином (героином) (обзор)

This review presents current data on the mechanism of action, selective toxicity, toxicokinetics and toxicodynamics of diacetylmorphine (heroin). Acute diacetylmorphine poisoning is considered under taking into account the developing a critical state, in which the poisoning severity is determined by severe metabolic disorders associated with the progression of hypoxia. The main lifethreatening complications of acute diacetyl morphine poisoning are described including those associated with the nervous system, respiratory, circulatory and urinary systems. Since hypoxia is the principal damaging factor, the the mechanisms of oxygen transport disorders and the pathogenesis of activation of free radical oxidation in acute diacetylmorphine poisoning are discussed. The improvement of intensive care strategy for severe forms of acute diacetylmorphine poisoning by the inclusion of a substrate antihypoxant Reamberin into the list of routine critical care prescriptions is emphesized.В обзоре представлены современные данные о механизме действия, избирательной токсичности, токсикокинетике и токсикодинамике диацетилморфина (героина). Острые отравления диацетилморфином рассмотрены в аспекте формирования критического состояния, при котором тяжесть отравления обусловлена развитием выраженных метаболических расстройств, связанных с прогрессированием гипоксии. Описаны основные жизнеопасные осложнения, которые возникают вследствие острых отравлений диацетилморфином со стороны ЦНС, системы дыхания, кровообращения, мочевыделительной системы. Учитывая, что основным фактором поражения является гипоксия, рассмотрены механизмы нарушений транспорта кислорода, а также патогенез активации свободнорадикального окисления при острых отравлениях диацетилморфином. Дано обоснование направлений совершенствования интенсивной терапии тяжелых форм острых отравлений диацетилморфином путем использования, помимо общереаниматологических мероприятий, субстратного антигипоксанта реамберина

Testing the Growth Rate Hypothesis in Vascular Plants with Above- and Below-Ground Biomass

The growth rate hypothesis (GRH) proposes that higher growth rate (the rate of change in biomass per unit biomass, μ) is associated with higher P concentration and lower C∶P and N∶P ratios. However, the applicability of the GRH to vascular plants is not well-studied and few studies have been done on belowground biomass. Here we showed that, for aboveground, belowground and total biomass of three study species, μ was positively correlated with N∶C under N limitation and positively correlated with P∶C under P limitation. However, the N∶P ratio was a unimodal function of μ, increasing for small values of μ, reaching a maximum, and then decreasing. The range of variations in μ was positively correlated with variation in C∶N∶P stoichiometry. Furthermore, μ and C∶N∶P ranges for aboveground biomass were negatively correlated with those for belowground. Our results confirm the well-known association of growth rate with tissue concentration of the limiting nutrient and provide empirical support for recent theoretical formulations