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Prime Example (prime + example)
Selected AbstractsPUEBLO MISSION CHURCHES AS SYMBOLS OF PERMANENCE AND IDENTITY,GEOGRAPHICAL REVIEW, Issue 3 2000KEVIN S. BLAKE ABSTRACT. The three Pueblo mission churches of San Esteban del Rey, Nuestra Señora de Guadalupe, and San José de Laguna are the most visually striking structures in the western New Mexico pueblos of Acoma, Zuni, and Laguna. Prime examples of "structures of permanence" on the landscape, the churches define local cultural identity. Church permanence and Pueblo identity are expressed in a five-part typology of visible characteristics: natural materials and hand labor, massive exterior form, adjoining cemeteries, syncretism of interior decorations, and structural decay and rebirth. Permanence must, however, be understood as an evolving condition, undergoing new representations as multicultural relationships evolve. [source] Policy Autonomy and the History of British Aid to AfricaDEVELOPMENT POLICY REVIEW, Issue 6 2005Tony Killick This article utilises historical information to throw light on the forces shaping British aid policies towards Africa. It outlines key long-term policy developments, summarises the influences shaping these policies and comments on the present juncture of UK policies. It shows that, while there have been many influences, governments have enjoyed considerable policy autonomy, being largely unconstrained in pursuing their preferences in a top-down manner. This autonomy has mainly been used for the pursuit of long-term development, as against the promotion of the UK's national interest. The present thrust of UK policies to achieve massive increases in aid to Africa is a prime example of this policy autonomy. [source] SAVINGS IN THE ABSENCE OF FUNCTIONING PROPERTY RIGHTS1ECONOMIC AFFAIRS, Issue 1 2007Nick Silver Nigeria is a prime example of a developing country with ill-defined property rights. However, people still manage to save, mostly through traditional and informal means, facilitated by strong family and community institutions. This paper argues that the government should concentrate on strengthening these institutions rather than weakening them by imposing an inappropriate, Western-style, formal pensions system on the country. [source] Regulation of erythropoietin productionEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 2005K.-U. Eckardt Abstract The glycoprotein hormone erythropoietin (EPO) is an essential growth and survival factor for erythroid progenitor cells, and the rate of red blood cell production is normally determined by the serum EPO concentration. EPO production is inversely related to oxygen availability, so that an effective feedback loop is established, which controls erythropoiesis. Since recombinant EPO became available as an effective therapeutic agent, significant progress has also been made in understanding the basis of this feedback control. The main determinant of EPO synthesis is the transcriptional activity of its gene in liver and kidneys, which is related to local oxygen tensions. This control is achieved by hypoxia-inducible transcription factors (HIF), consisting of a constitutive ,-subunit and one of two alternative oxygen-regulated HIF, subunits (HIF-1, and HIF-2,). In the presence of oxygen (normoxia) the HIF, subunits are hydroxylated, which targets them for proteasomal degradation. Under hypoxia, because of the lack of molecular oxygen, HIF cannot be hydroxylated and is thereby stabilized. Although HIF-1, was the first transcription factor identified through its ability to bind to an enhancer sequence of the EPO gene, more recent evidence suggests that HIF-2, is responsible for the regulation of EPO. Although EPO is a prime example for an oxygen- regulated gene, the role of the HIF system goes far beyond the regulation of EPO, because it operates widely in almost all cells and controls a broad transcriptional response to hypoxia, including genes involved in cell metabolism, angiogenesis and vascular tone. Further evidence suggests that apart from its effect as an erythropoietic hormone EPO acts as a paracrine, tissue-protective protein in the brain and possibly also in other organs. [source] Charge and Mass Transfer Across the Metal/Solution InterfaceISRAEL JOURNAL OF CHEMISTRY, Issue 3-4 2008Eliezer Gileadi Electrode reactions are characterized by charge transfer across the interface. The charge can be carried by electrons or by ions. It is shown here that when both mass and charge cross the interface, the charge must be carried by the ionic species, not by the electrons, as a result of the very large difference in the time scale for electron and ion transfer. A prime example of charge transfer by ions is metal deposition. It is proposed that ion transfer occurs by migration of the ions across the interface, under the influence of the high electrostatic field in the double layer. The rate constants observed for metal deposition are comparable to those for outer-sphere charge transfer. These unexpectedly high rate constants for metal deposition are explained by a model in which removal of the solvation shell and reduction of the effective charge on the metal ion occur in many small steps, and a make-before-break mechanism exists, which lowers the total Gibbs energy of the system as it moves along the reaction coordinate from the initial to the final state. [source] What controls woodland regeneration after elephants have killed the big trees?JOURNAL OF APPLIED ECOLOGY, Issue 1 2009Stein R. Moe Summary 1Top-down regulation of ecosystems by large herbivores is a topic of active debate between scientists and managers, and a prime example is the interaction between elephants Loxodonta africana and trees in African savannas. A common assumption among wildlife managers is that a local reduction in elephant numbers will ultimately allow woodland to self-restore to a desired former state. Such regeneration is, however, dependent on the survival of seedlings of impacted tree species. We conducted a field experiment to investigate seedling predation in the elephant-transformed Chobe riparian woodland of northern Botswana. 2We planted seedling gardens in (i) complete exclosures that excluded all herbivores except small rodents and invertebrates, (ii) semi-permeable exclosures that excluded ungulates but included primates, lagomorphs, all rodents, gallinaceous birds, etc, and (iii) completely open plots. Seedlings were of two tree species decreasing in the area (Faidherbia albida and Garcinia livingstonei) and two that are increasing (Combretum mossambicense and Croton megalobotrys). 3After 9 months, seedling survival ranged from >75% for all species in the complete exclosure to <20% for Faidherbia albida in the open plots. Survival of all seedlings except C. megalobotrys declined precipitously in open plots during the dry season when invertebrates are largely dormant but when impalas Aepyceros melampus (locally abundant ungulates) increase the browse components of their diets. 4Seedling survival in the open plots was negatively related to local impala density but unrelated to that of any other browser. 5Synthesis and applications. Our findings relate to the current debate about managing elephants to restore southern African savanna landscapes to desired historical states. Various seedling predators, including the ubiquitous impala Aepyceros melampus, regulate the regeneration of trees from seedlings, and our experiments support the hypothesis that tall closed-canopy woodlands originate during episodic windows of opportunity for seedling survival. To artificially recreate such a window would require the decimation of seedling predators as well as elephants, which is impractical at the landscape scale. [source] Greece: How can companies manage the new risks?JOURNAL OF CORPORATE ACCOUNTING & FINANCE, Issue 6 2010Bento J. Lobo CEOs and CFOs must understand that political risk can have a significant impact on a company's profitability. The current situation in Greece is a prime example of this. But how does the risk of Greece's default affect U.S. firms doing business with Greek companies? The authors examine the impact on two kinds of U.S. firms: those exporting to Greece and those importing from Greece. The authors then look at ways to manage the impact of sovereign risk of default. © 2010 Wiley Periodicals, Inc. [source] Solid-solid reactions in series: A modeling and experimental studyAICHE JOURNAL, Issue 9 2009A. K. Suresh Abstract Reactions among particulate solid phases are important and abundant in many materials, chemical, and metallurgical process industries. Many of these are reaction networks, and not single-step reactions as normally assumed. There is no theoretical framework available for the analysis of such systems, and single-reaction models derived from the gas,solid literature continue to be used. Formation of cement clinker in the rotary cement kiln is a prime example of the genre, in which mechanistic aspects play an important role in determining energy efficiency and the composition and nature of the phases that form. In the present study, we formulate a model within the ambit of the "shrinking core" class of models, for reactions in series among solid phases. The model shows the presence of one or two moving fronts in the reacting particle, depending on the relative rates of the processes involved. A single Thiele-type parameter controls the model behavior, at once describing the relative rates of the intermediate formation and consumption processes, and the diffusion-reaction competition for the product formation step. The model has been shown to reduce to the well known single reaction models at the limits of low and high values of the Thiele parameter. Experimental data have been obtained on the calcia-alumina system, an important one in cement manufacture, in the temperature range 1150,1250°C. The model has been fitted to these data and the kinetic parameters determined. The comparison bears out the salient features of the theory, and shows that a degree of diffusion limitation exists for the intermediate conversion step under these conditions. The diffusivity values estimated are in the range of 10,19 to 10,18 m2/s and agree with values found in the literature for similar systems. The rate constant for the intermediate conversion step is of the order of 10,6 s,1. This being among the first such determinations, this value awaits confirmation from other studies. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] On the business value and technical challenges of adopting Web servicesJOURNAL OF SOFTWARE MAINTENANCE AND EVOLUTION: RESEARCH AND PRACTICE, Issue 1-2 2004S. Tilley Abstract This paper provides a balanced perspective of the business value and technical challenges of adopting Web services. Technology adoption is a continual challenge for both tool developers and enterprise users. Web services are a prime example of an emerging technology that is fraught with adoption issues. Part of the problem is separating marketing hype from business reality. Web services are network-accessible interfaces to application functionality. They are built using Internet technologies such as XML and standard protocols such as SOAP. The adoption issues related to Web services are complex and multifaceted. For example, determining whether this technology is a fundamental advance, rather than something old under a new name, requires technical depth, business acumen, and considerable historical knowledge of past developments. A sample problem from the health care industry is used to illustrate some of the adoption issues. Copyright © 2004 John Wiley & Sons, Ltd. [source] The cellular level of the recognition factor RssB is rate-limiting for ,S proteolysis: implications for RssB regulation and signal transduction in ,S turnover in Escherichia coliMOLECULAR MICROBIOLOGY, Issue 6 2002Mihaela Pruteanu Summary Degradation of the general stress sigma factor ,S of Escherichia coli is a prime example of regulated proteolysis in prokaryotes. Whereas exponentially growing cells rapidly degrade ,S, various stress conditions result in stabilization and, therefore, rapid accumulation of ,S. Proteolysis of ,S requires the response regulator RssB, a direct recognition factor with phosphorylation-dependent affinity for ,S, which targets ,S to the ClpXP protease. Here, we demonstrate that a sudden increase in ,S synthesis results in ,S stabilization, indicating titration of an essential proteolytic component. Evidence is provided that RssB is the overall rate-limiting factor for ,S proteolysis. As a consequence, the cell has to continuously adjust the expression of RssB to ,S in order to maintain ,S proteolysis in growing cells, despite variations in the rate of ,S synthesis. Such homeostatic feedback-coupling is provided by rssB transcription being dependent on the ,S -controlled rssAB operon promoter. However, strong and rapid increases in ,S synthesis, in re-sponse to acute stress, exceed the compensatory potential of this feedback loop with the result that ,S is stabilized because of RssB titration. We propose that RssB control of ,S proteolysis functions as a genetic switch, in which (i) the ,off' state (low ,S levels caused by proteolysis) is stabilized by a homeostatic negative feedback, and (ii) the threshold for switching to the ,on' state (high levels of stable ,S) is dependent on the cellular level of active, i.e. phosphorylated RssB. [source] Remodeling protein complexes: Insights from the AAA+ unfoldase ClpX and Mu transposasePROTEIN SCIENCE, Issue 8 2005Briana M. Burton Abstract Multiprotein complexes in the cell are dynamic entities that are constantly undergoing changes in subunit composition and conformation to carry out their functions. The protein,DNA complex that promotes recombination of the bacteriophage Mu is a prime example of a complex that must undergo specific changes to carry out its function. The Clp/Hsp100 family of AAA+ ATPases plays a critical role in mediating such changes. The Clp/Hsp100 unfolding enzymes have been extensively studied for the roles they play in protein degradation. However, degradation is not the only fate for proteins that come in contact with the ATP-dependent unfolding enzymes. The Clp/Hsp100 enzymes induce structural changes in their substrates. These structural changes, which we refer to as "remodeling," ultimately change the biological activity of the substrate. These biological changes include activation, inactivation (not associated with degradation), and relocation within the cell. Analysis of the interaction between Escherichia coli ClpX unfoldase and the Mu recombination complex, has provided molecular insight into the mechanisms of protein remodeling. We discuss the key mechanistic features of the remodeling reactions promoted by ClpX and possible implications of these findings for other biological reactions. [source] Development, repair and fibrosis: What is common and why it mattersRESPIROLOGY, Issue 5 2009Wei SHI ABSTRACT The complex structure of the lung is developed sequentially, initially by epithelial tube branching and later by septation of terminal air sacs with accompanying coordinated growth of a variety of lung epithelial and mesenchymal cells. Groups of transcriptional factors, peptide growth factors and their intracellular signaling regulators, as well as extracellular matrix proteins are programmed to be expressed at appropriate levels in the right place at the right time to control normal lung formation. Studies of lung development and lung repair/fibrosis to date have discovered that many of the same factors that control normal development are also key players in lung injury repair and fibrosis. Transforming growth factor-, (TGF-,) family peptide signaling is a prime example. Lack of TGF-, signaling results in abnormal lung branching morphogenesis and alveolarization during development, whereas excessive amounts of TGF-, signaling cause severe hypoplasia in the immature lung and fibrosis in mature lung. This leads us to propose the ,Goldilocks' hypothesis of regulatory signaling in lung development and injury repair that everything must be done just right! [source] Phytochrome-mediated agravitropism in Arabidopsis hypocotyls requires GIL1 and confers a fitness advantageTHE PLANT JOURNAL, Issue 4 2006Trudie Allen Summary Plants use specialized photoreceptors to detect the amount, quality, periodicity and direction of light and to modulate their growth and development accordingly. These regulatory light signals often interact with other environmental cues. Exposure of etiolated Arabidopsis seedlings to red (R) or far-red (FR) light causes hypocotyls to grow in random orientations with respect to the gravitational vector, thus overcoming the signal from gravity to grow upwards. This light response, mediated by either phytochrome A or phytochrome B, represents a prime example of cross-talk between environmental signalling systems. Here, we report the isolation the mutant gil1 (for gravitropic in the light) in which hypocotyls continue to grow upwards after exposure of seedlings to R or FR light. The gil1 mutant displays no other phenotypic alterations in response to gravity or light. Cloning of GIL1 has identified a novel gene that is necessary for light-dependent randomization of hypocotyl growth orientation. Using gil1, we have demonstrated that phytochrome-mediated randomization of Arabidopsis hypocotyl orientation provides a fitness advantage to seedlings developing in patchy, low-light environments. [source] Distinctiveness of macroinvertebrate communities in turloughs (temporary ponds) and their response to environmental variablesAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 4 2009Gwendolin Porst Abstract 1.Turloughs are a prime example of a water body type that interfaces with both the European Habitats Directive (92/43/EEC) and Water Framework Directive (2000/60/EC) (WFD), highlighting the need for an integrated strategy to protect and manage surface waters and groundwaters. To date, research on turloughs, including their invertebrate communities is limited. 2.Eight turloughs were sampled for their macroinvertebrate communities and water chemistry in April 2007. Faunal samples were collected by means of a simple box sampler. 3.Replicate samples within each turlough clustered together, indicating that a single sample can provide a meaningful description of the turlough invertebrate community. Variation of invertebrate communities within turloughs was nested among turloughs. 4.Hydroperiod influenced mean abundance and taxon richness of macroinvertebrates, but no correlation was found between nutrient status and either mean abundance or taxon richness. 5.Turloughs are priority habitats under the EC Habitats Directive, requiring maintenance of ,favourable conservation status', which needs to be assessed through monitoring, and effected through appropriate management plans. While the distinctiveness of macroinvertebrate communities across turloughs is conducive to simple and cost-effective monitoring, this also challenges the applicability of the concept of type-specific communities across these highly dynamic ecosystems. Copyright © 2009 John Wiley & Sons Ltd. [source] Proteus in the World of Proteins: Conformational Changes in Protein KinasesARCHIV DER PHARMAZIE, Issue 4 2010Matthias Rabiller Abstract The 512 protein kinases encoded by the human genome are a prime example of nature's ability to create diversity by introducing variations to a highly conserved theme. The activity of each kinase domain is controlled by layers of regulatory mechanisms involving different combinations of post-translational modifications, intramolecular contacts, and intermolecular interactions. Ultimately, they all achieve their effect by favoring particular conformations that promote or prevent the kinase domain from catalyzing protein phosphorylation. The central role of kinases in various diseases has encouraged extensive investigations of their biological function and three-dimensional structures, yielding a more detailed understanding of the mechanisms that regulate protein kinase activity by conformational changes. In the present review, we discuss these regulatory mechanisms and show how conformational changes can be exploited for the design of specific inhibitors that lock protein kinases in inactive conformations. In addition, we highlight recent developments to monitor ligand-induced structural changes in protein kinases and for screening and identifying inhibitors that stabilize enzymatically incompetent kinase conformations. [source] Turtles as hopeful monstersBIOESSAYS, Issue 11 2001Olivier Rieppel A recently published study on the development of the turtle shell(1) highlights the important role that development plays in the origin of evolutionary novelties(1). The evolution of the highly derived adult anatomy of turtles is a prime example of a macroevolutionary event triggered by changes in early embryonic development. Early ontogenetic deviation may cause patterns of morphological change that are not compatible with scenarios of gradualistic, stepwise transformation. BioEssays 23:987,991, 2001. © 2001 John Wiley & Sons, Inc. [source] | ||||||||||||||||||||||