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Selected AbstractsReversible transition between active and dormant microbial states in soilFEMS MICROBIOLOGY ECOLOGY, Issue 2-3 2001John Stenström Abstract The rate of respiration obtained in the substrate-induced respiration (SIR) method can be divided into the respiration rate of growing (r) and non-growing (K) microorganisms. The fraction of r is generally small (5,20%) in soils with no recent addition of substrates, but can be 100% in soils with high substrate availability. This suggests that substrate availability determines the proportion of biomass between these groups, and implies that transitions between them can take place reversibly. These hypotheses were tested by adding three different amounts of glucose which induced first-order, zero-order, and growth-associated respiration kinetics to three soils at four pre-incubation times (4, 12, 27, and 46 days) before the SIR measurement. An abiotic flush of CO2 in the SIR measurement was detected and corrected for before data analysis. Accumulated CO2 -C over 4 days after glucose addition, corrected for the respiration in unamended controls, corresponded to 41,50% mineralization of the glucose-C, and the relative amount mineralized by each soil was independent of the glucose amount added. The high glucose concentration gave an increased SIR, which reverted to the initial value within 27,46 days. In a specific sample, the maximum respiration rate induced during the pre-incubation, and the amount of organisms transformed from the K to the r state, as quantified in respiration rate units in the SIR measurement, were identical to each other, and these parameters were also highly correlated to the initial glucose concentration. The K,r transition was very fast, probably concurrent with the instantaneous increase in the respiration rate obtained by the glucose amendment. Thereafter, a slow first-order back-transition from the r to the K state ensued, with half-lives of 12, 23, and 70 days for the three soils. The results suggest the existence of community-level controls by which growth within or of the whole biomass is inhibited until it has been completely transformed into the r state. The data also suggest that the microbial specific activity is not related to the availability of exogenous substrate in a continuous fashion, rather it responds as a sharp transition between dormant and fully active. Furthermore, the inherent physiological state of the microbial biomass is strongly related to its history. It is proposed that the normal dynamics of the soil microbial biomass is an oscillation between active and dormant physiological states, while significant growth occurs only at substantial substrate amendment. [source] Structural and functional features of factor XIJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 2009D. GAILANI Summary., Factor XI (FXI) has structural and mechanistic features that distinguish it from other coagulation proteases. A relatively recent addition to vertebrate plasma coagulation, FXI is a homodimer, with each subunit containing four apple domains and a protease domain. The apple domains form a disk structure with binding sites for platelets, high molecular weight kininogen, and the substrate factor IX (FIX). FXI is converted to the active protease FXIa by cleavage of the Arg369,Ile370 bond on each subunit. This converts the catalytic domains to the active forms, and unmasks exosites on the apple domains required for FIX binding. FXI activation by factor XIIa or thrombin proceeds through an intermediate with only one activated submit (1/2-FXIa). 1/2-FXIa activates FIX in a similar manner to FXIa. While the importance of the homodimeric structure of FXI is not certain, it may represent a strategy for binding to FIX and a platelet surface simultaneously. [source] The Conceptual History of Social JusticePOLITICAL STUDIES REVIEW, Issue 3 2005Ben Jackson Social justice is a crucial ideal in contemporary political thought. Yet the concept of social justice is a recent addition to our political vocabulary, and comparatively little is known about its introduction into political debate or its early theoretical trajectory. Some important research has begun to address this issue, adding a valuable historical perspective to present-day controversies about the concept. This article uses this literature to examine two questions. First, how does the modern idea of social justice differ from previous conceptualisations of justice? Second, why and when did social justice first emerge into political discourse? [source] Acute Myocardial Infarction and Acute Coronary Syndrome: Then and Now (1950,2005)PREVENTIVE CARDIOLOGY, Issue 4 2006Monte Malach MD Advances in the prevention, diagnosis, and treatment of acute myocardial infarction (AMI) and acute coronary syndrome (ACS) have been remarkable since the mid-20th century. Even the clinical terminology used to describe some of the various components of ACS have undergone change, while the latter term itself represents a fairly recent addition to the medical lexicon. Although there have been dramatic changes in the diagnostic and therapeutic interventions used and impressive declines in morbidity and mortality, the differential diagnosis and complications of AMI and ACS remain as challenging now as they were a half century ago. This article presents in detail the medical understanding of AMI in the mid-20th century and how physicians of that era managed it and its complications, and contrasts this with current evidence-based knowledge and interventions. [source] A new player in a deadly game: influenza viruses and the PI3K/Akt signalling pathwayCELLULAR MICROBIOLOGY, Issue 6 2009Christina Ehrhardt Summary Upon influenza A virus infection of cells, a wide variety of antiviral and virus-supportive signalling pathways are induced. Phosphatidylinositol-3-kinase (PI3K) is a recent addition to the growing list of signalling mediators that are activated by these viruses. Several studies have addressed the role of PI3K and the downstream effector protein kinase Akt in influenza A virus-infected cells. PI3K/Akt signalling is activated by diverse mechanisms in a biphasic manner and is required for multiple functions during infection. While the kinase supports activation of the interferon regulatory factor-3 during antiviral interferon induction, it also exhibits virus supportive functions. In fact, PI3K not only regulates a very early step during viral entry but also results in suppression of premature apoptosis at later stages of infection. The latter function is dependent on the expression of the viral non-structural protein-1 (A/NS1). It has been shown that PI3K activation occurs by direct interaction of A/NS1 with the p85 regulatory subunit and interaction sites of A/NS1 and p85 have now been mapped in detail. Here, we summarize the current knowledge on influenza virus-induced PI3K signalling and how this pathway supports viral propagation. [source] Resource Consumption of New Urban Construction in ChinaJOURNAL OF INDUSTRIAL ECOLOGY, Issue 2 2007John E. Fernández The volume of China's recent additions to its urban-built environment is unprecedented. China now accounts for half of all new building area in the world. Increases in building stocks of all types have occurred during an extended period of accelerated growth of the national economy. This expansion promises to continue through 2030. As a result, the rapid conversion of land from low-density agricultural and light manufacturing to new urban zones of high density and material-intensive commercial and residential buildings has consumed enormous quantities of domestic and imported resources and has irreversibly altered the Chinese landscape. This article examines the consumption of material resources dedicated to Chinese building construction through a survey and analysis of the material intensity of three major building types. This provides a basis for outlining the emerging life-cycle issues of recent additions to the built environment and of continued construction. With this as the starting point, the field of industrial ecology can work toward formulating strategies for a circular economy that include a resource-efficient urban China. [source] Whatever Happened to Thatcherism?POLITICAL STUDIES REVIEW, Issue 2 2007Colin Hay Throughout the 1980s and the early 1990s the pages of journals such as this were filled with debate , invariably heated , on the nature, extent, significance and reversibility of Thatcherism. Today the echoes of a once deafening clamour have largely subsided. Thatcherism has all but disappeared from the lexicon of British political analysis. My aim in what follows is to reflect on this passing and what it indicates about the state of our understanding of this once most contentious of phenomena. I do so by considering the two most significant recent additions to the vast literature on the subject, Peter Kerr's Postwar British Politics: From Conflict to Consensus (2001) and Richard Heffernan's New Labour and Thatcherism: Political Change in Britain (2000).1 [source] Comovement After Joining an Index: Spillovers of Nonfundamental EffectsREAL ESTATE ECONOMICS, Issue 1 2007Brent W. Ambrose This study considers the case of two overlapping categories in the context of recent category models. Specifically, we examine whether investor sentiment and market frictions specific to one category can affect the returns on assets belonging to the other category. With recent additions of several real estate investment trusts (REITs) into general stock market indices as a natural experiment, we find support for spillovers of such nonfundamental effects, as evidenced by the increased return correlation between REITs that remain outside the index and the index stocks. Further analysis reveals that market frictions play a greater role than investor sentiment. [source] MrBUMP: an automated pipeline for molecular replacementACTA CRYSTALLOGRAPHICA SECTION D, Issue 1 2008Ronan M. Keegan A novel automation pipeline for macromolecular structure solution by molecular replacement is described. There is a special emphasis on the discovery and preparation of a large number of search models, all of which can be passed to the core molecular-replacement programs. For routine molecular-replacement problems, the pipeline automates what a crystallographer might do and its value is simply one of convenience. For more difficult cases, the pipeline aims to discover the particular template structure and model edits required to produce a viable search model and may succeed in finding an efficacious combination that would be missed otherwise. An overview of MrBUMP is given and some recent additions to its functionality are highlighted. [source] | |||||||||||||