1,019 research outputs found
Infrastructure and economic growth in East Asia
This paper examines whether infrastructure investment has contributed to East Asia's economic growth using both a growth accounting framework and cross-country regressions. For most of the variables used, both the growth accounting exercise and cross-country regressions fail to find a significant link between infrastructure, productivity and growth. These conclusions contrast strongly with previous studies finding positive and significant effect for all infrastructure variables in the context of a production function study. This leads us to conclude that results from studies using macro-level data should be considered with extreme caution. The Authors suggest that infrastructure investment may have had the primary function of relieving constraints and bottlenecks as they arose, as opposed to directly encouraging growth.Transport Economics Policy&Planning,Banks&Banking Reform,Achieving Shared Growth,Economic Theory&Research,Non Bank Financial Institutions
Anterograde Signalling by Nitric Oxide: Characterisation and In Vitro Reconstitution of an Identified Nitrergic Synapse
Nitric oxide (NO) is recognized as a signaling molecule in the CNS where it is a candidate retrograde neurotransmitter. Here we provide direct evidence that NO mediates slow excitatory anterograde transmission between the NO synthase (NOS)-expressing B2 neuron and an NO-responsive follower neuron named B7nor. Both are motoneurons located in the buccal ganglia of the snail Lymnaea stagnalis where they participate in feeding behavior. Transmission between B2 and B7nor is blocked by inhibiting NOS and is suppressed by extracellular scavenging of NO. Furthermore, focal application of NO to the cell body of the B7nor neuron causes a depolarization that mimics the effect of B2 activity. The slow interaction between the B2 and B7nor neurons can be re-established when the two neurons are cocultured, and it shows the same susceptibility to NOS inhibition and NO scavenging. In cell culture we have also examined spatial aspects of NO signaling. We show that before the formation of an anatomical connection, the presynaptic neuron can cause depolarizing potentials in the follower neuron at distances up to 50 micro(m). The strength of the interaction increases when the distance between the cells is reduced. Our results suggest that NO can function as both a synaptic and a nonsynaptic signaling molecul
Competition and Civic Engagement in the Religious Marketplace
We develop a model of spatial competition to explain the high level of spending on social services that distinguishes American churches or faith-based organizations (FBOs). The model predicts that such spending, measured on a per member basis, rises as the equilibrium structure of the religious marketplace becomes more competitive. A simple test of the model using measures of a religious Herfindahl Index constructed by county and by year for panel data covering the years 1994 and 2000 confirms our analysis. As local FBO monopoly power grows, FBO spending on civic activities declines.
Associative memory stored by functional novel pathway rather than modifications of preexisting neuronal pathways
Associative conditioning involves changes in the processing pathways activated by sensory information to link the conditioned stimulus (CS) to the conditioned behavior. Thus, conditioning can recruit neuronal elements to form new pathways for the processing of the CS and/or can change the strength of existing pathways. Using a behavioral and systems level electrophysiological approach on a tractable invertebrate circuit generating feeding in the mollusk Lymnaea stagnalis, we identified three independent pathways for the processing of the CS amyl acetate used in appetitive conditioning. Two of these pathways, one suppressing and the other stimulating feeding, mediate responses to the CS in naive animals. The effects ofthese two pathways on feeding behavior are unaltered by conditioning. In contrast, the CS response ofa third stimulatory pathway is significantly enhanced after conditioning, becoming an importantcontributor to the overall CS response. This is unusual because, in most of the previous examples in which naive animals already respond to the CS, memory formation results from changes in the strength of pathways that mediate the existing response. Here, we show that, in the molluscan feeding system, both modified and unmodified pathways are activated in parallel by the CS after conditioning, and it is their integration that results in the conditioned respons
A framework for assessing global imbalances
In this paper, we take a systematic look at global imbalances. First, we provide a definition of the phenomenon, and relate global imbalances to widening external positions of systemically important economies that reflect distortions or entail risks for the global economy. Second, we provide an operational content to this definition by measuring trends in external imbalances over the past decade and putting these in a historical perspective. We argue that three main features set today’s situation apart from past episodes of growing external imbalances - (i) the emergence of new players, in particular emerging market economies such as China and India, which are quickly catching up with the advanced economies; (ii) an unprecedented wave of financial globalisation, with more integrated global financial markets and increasing opportunities for international portfolio diversification, also characterised by considerable asymmetries in the level of market completeness across countries; and (iii) the favourable global macroeconomic and financial environment, with record high global growth rates in recent years, low financial market volatility and easy global financing conditions over a long time period of time, running at least until the summer of 2007. Finally, we provide an analytical overview of the fundamental causes and drivers of global imbalances. The central argument is that the increase in imbalances has been driven by a unique combination of structural and cyclical determinants. JEL Classification: F2, F32, F33, F41.Gobal imbalances, current account, incomplete financial globalisation, structural factors, cyclical factors.
Untersuchungen zur Aquiferdynamik im Einzugsgebiet des Blautopfs (Oberjura, Süddeutschland)
Armbruster, V.; Selg, M.: Der Abfluss des Blautopfs im Spiegel der Grundwasserneubildung
Bauer, M.; Selg, M.: Altersstruktur und Mittlere Verweilzeit im Grundwasser des Blautopfs und anderer Quellen und Brunnen im Oberjura-Karst Süddeutschlands
Selg, M.; Schopper, M.; Straub, R.: Kurzzeitdynamik und Direktabfluss des Blautopf
How Does Individual Recognition Evolve? Comparing Responses to Identity Information in P olistes Species with and Without Individual Recognition
A wide range of complex social behaviors are facilitated by the recognition of individual conspecifics. Individual recognition requires sufficient phenotypic variation to provide identity information as well as receivers that process and respond to identity information. Understanding how a complex trait such as individual recognition evolves requires that we consider how each component has evolved. Previous comparative studies have examined phenotypic variability in senders and receiver learning abilities, although little work has compared receiver responses to identity information among related species with and without individual recognition. Here, we compare responses to identity information in two Polistes paper wasps: P. fuscatus, which visually recognizes individuals, and P. metricus , which does not normally show evidence of individual recognition. Although the species differ in individual recognition, the results of this study show that receiver responses to experimentally manipulated identity information are surprisingly similar in both species. Receivers direct less aggression toward identifiable individuals than unidentifiable individuals. Therefore, the responses necessary for individual recognition may pre‐date its evolution in the P. fuscatus lineage. Additionally, our data demonstrate the apparent binary differences in a complex behavior between the two species, such as individual recognition, likely involve incremental differences along a number of axes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102093/1/eth12191.pd
Timed and targeted differential regulation of nitric oxide synthase (NOS) and anti-NOS genes by reward conditioning leading to long-term memory formation
In a number of neuronal models of learning, signaling by the neurotransmitter nitric oxide (NO), synthesized by the enzyme neuronal NO synthase (nNOS), is essential for the formation of long-term memory (LTM). Using the molluscan model system Lymnaea, we investigate here whether LTM formation is associated with specific changes in the activity of members of the NOS gene family: Lym-nNOS1, Lym-nNOS2, and the antisense RNA-producing pseudogene (anti-NOS). We show that expression of the Lym-nNOS1 gene is transiently upregulated in cerebral ganglia after conditioning. The activation of the gene is precisely timed and occurs at the end of a critical period during which NO is required for memory consolidation. Moreover, we demonstrate that this induction of the Lym-nNOS1 gene is targeted to an identified modulatory neuron called the cerebral giant cell (CGC). This neuron gates the conditioned feeding response and is an essential part of the neural network involved in LTM formation. We also show that the expression of the anti-NOS gene, which functions as a negative regulator of nNOS expression, is downregulated in the CGC by training at 4 h after conditioning, during the critical period of NO requirement. This appears to be the first report of the timed and targeted differential regulation of the activity of a group of related genes involved in the production of a neurotransmitter that is necessary for learning, measured in an identified neuron of known function. We also provide the first example of the behavioral regulation of a pseudogene
Preparation of Chiral Enantioenriched Densely Substituted Cyclopropyl Azoles, Amines, and Ethers via Formal SN2′ Substitution of Bromocylopropanes
Enantiomerically enriched cyclopropyl ethers, amines, and cyclopropylazole derivatives possessing three stereogenic carbon atoms in a small cycle are obtained via the diastereoselective, formal nucleophilic substitution of chiral, non-racemic bromocyclopropanes. The key feature of this methodology is the utilization of the chiral center of the cyclopropene intermediate, which governs the configuration of the two adjacent stereocenters that are successively installed via 1,4-addition/epimerization sequence
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