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Large Fluctuations (large + fluctuation)
Selected AbstractsEconomic development and fluctuations in earnings inequality in the very long run: The evidence from Latin America 1900,2000JOURNAL OF INTERNATIONAL DEVELOPMENT, Issue 8 2008Valpy FitzGerald Abstract Latin America has the most unequal income distribution of any region in the world, yet its historical causes are poorly understood. This paper reports the first exploratory attempt to compute income distributions for the five leading Latin American economies for the whole 20th century. The methodology produces estimates of earnings dispersion for four skill groups over 1900,2000, which can be used to generate the familiar Gini coefficients. Large fluctuations in dispersion over time are found: countering claims of stability since the colonial past in the recent economic institutions literature; but supporting the findings of economic historians and development economists. An estimation model (reflecting the impact of international trade, labour quality and macroeconomic imbalances) explains the data reasonably well, with all three sets of drivers proving significant, although the measured effects are different across the five countries. The paper concludes that the skill composition of the workforce not only underpins long run trends in income distribution; but also conditions inequality fluctuations in response to exogenous shocks. Copyright © 2008 John Wiley & Sons, Ltd. [source] Molecular analysis of ammonia oxidation and denitrification in natural environmentsFEMS MICROBIOLOGY REVIEWS, Issue 5 2000Hermann Bothe Abstract This review summarizes aspects of the current knowledge about the ecology of ammonia-oxidizing and denitrifying bacteria. The development of molecular techniques has contributed enormously to the rapid recent progress in the field. Different techniques for doing so are discussed. The characterization of ammonia-oxidizing and -denitrifying bacteria by sequencing the genes encoding 16S rRNA and functional proteins opened the possibility of constructing specific probes. It is now possible to monitor the occurrence of a particular species of these bacteria in any habitat and to get an estimate of the relative abundance of different types, even if they are not culturable as yet. These data indicate that the composition of nitrifying and denitrifying communities is complex and apparently subject to large fluctuations, both in time and in space. More attempts are needed to enrich and isolate those bacteria which dominate the processes, and to characterize them by a combination of physiological, biochemical and molecular techniques. While PCR and probing with nucleotides or antibodies are primarily used to study the structure of nitrifying and denitrifying communities, studies of their function in natural habitats, which require quantification at the transcriptional level, are currently not possible. [source] Variation in abundance of Norwegian spring-spawning herring (Clupea harengus, Clupeidae) throughout the 20th century and the influence of climatic fluctuationsFISH AND FISHERIES, Issue 3 2000R. Toresen A long-term (1907,98) virtual population analysis (VPA) was made for Norwegian spring-spawning herring (NSSH), which is a huge pelagic fish stock in the north-east Atlantic. It shows that this herring stock has had large fluctuations during the last century; these fluctuations have mainly been determined by variations in the temperature of the inflowing water masses to the region. The spawning stock biomass (SSB) increased from a rather low level in the early years of this century and reached a high level of around 14 million tons by 1930. The spawning stock biomass then decreased to a level of around 10 million tons by 1940, but increased again to a record high level of 16 million tons by 1945. The stock then started to decrease and during the next 20-year period fell to a level of less than 50 000 tons by the late 1960s. Through the 1970s and 1980s, the stock slowly recovered and after the recruitment of strong year classes in 1983 and 1990,1992 the stock recovered to a spawning stock biomass of about 10 million tons. The long-term fluctuation in spawning stock biomass is caused by variations in the survival of recruits. It is found that the long-term changes in spawning stock abundance are highly correlated with the long-term variations in the mean annual temperature of the inflowing Atlantic water masses (through the Kola section) into the north-east Atlantic region. The recruitment is positively correlated with the average temperature in the Kola section in the winter months, January,April, which indicates that environmental factors govern the large-scale fluctuations in production for this herring stock. [source] Regeneration patterns and persistence of the fog-dependent Fray Jorge forest in semiarid Chile during the past two centuriesGLOBAL CHANGE BIOLOGY, Issue 1 2008ALVARO G. GUTIÉRREZ Abstract The persistence of rainforest patches at Fray Jorge National Park (FJNP) in semiarid Chile (30°40,S), a region receiving approximately 147 mm of annual rainfall, has been a source of concern among forest managers. These forests are likely dependent on water inputs from oceanic fog and their persistence seems uncertain in the face of climate change. Here, we assessed tree radial growth and establishment during the last two centuries and their relation to trends in climate and canopy disturbance. Such evaluation is critical to understanding the dynamics of these semiarid ecosystems in response to climate change. We analyzed forest structure of six forest patches (0.2,22 ha) in FJNP based on sampling within 0.1 ha permanent plots. For the main canopy species, the endemic Aextoxicon punctatum (Aextoxicaceae), we used tree-ring analysis to assess establishment periods, tree ages, growing trends and their relation to El Niño Southern Oscillation (ENSO), rainfall, and disturbance. The population dynamics of A. punctatum can be described by a continuous regeneration mode. Regeneration of A. punctatum was sensitive to different canopy structures. Growth release patterns suggest the absence of large scale human impact. Radial growth and establishment of A. punctatum were weakly correlated with rainfall and ENSO. If water limits forests patch persistence, patches are likely dependent on the combination of fog and rain water inputs. Forest patches have regenerated continuously for at least 250 years, despite large fluctuations in rainfall driven by ENSO and a regional decline in rainfall during the last century. Because of the positive influence on fog interception, forest structure should be preserved under any future climate scenario. Future research in FJNP should prioritize quantifying the long-term trends of fog water deposition on forests patches. Fog modeling is crucial for understanding the interplay among physical drivers of water inputs under climate change. [source] A Proposed Monetary Regime for Small Commodity Exporters: Peg the Export Price (,PEP')INTERNATIONAL FINANCE, Issue 1 2003Jeffrey Frankel On the one hand, the big selling points of floating exchange rates , monetary independence and accommodation of terms of trade shocks , have not lived up to their promise. On the other hand, proposals for credible institutional monetary commitments to nominal anchors have each run aground on their own peculiar shoals. Rigid pegs to the dollar are dangerous when the dollar appreciates. Money targeting does not work when there is a velocity shock. CPI targeting is not viable when there is a large import price shock. And the gold standard fails when there are large fluctuations in the world gold market. This paper advances a new proposal called PEP: peg the export price. Most applicable for countries that are specialized in the production of a particular mineral or agricultural product, the proposal calls on them to commit to fix the price of that commodity in terms of domestic currency. A series of simulations shows how such a proposal would have worked for oil producers over the period 1970,2000. The paths of real oil prices, exports, and debt are simulated under alternative regimes. An illustrative finding is that countries that suffered a declining world market in oil or other export commodities in the late 1990s would under the PEP proposal have automatically experienced a depreciation and a boost to exports when it was most needed. The argument for PEP is that it simultaneously delivers automatic accommodation to terms of trade shocks, as floating exchange rates are supposed to do, while retaining the credibility-enhancing advantages of a nominal anchor, as dollar pegs are supposed to do. [source] Helium pre-enrichment in the first starsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY: LETTERS (ELECTRONIC), Issue 1 2006Leonid Chuzhoy ABSTRACT We show that element diffusion can produce large fluctuations in the initial helium abundance of stars. Diffusion time-scale, which in stellar cores is much larger than the Hubble time, can fall below 108 yr in the neutral gas clouds of stellar mass, dominated by collisionless dark matter or with dynamically important radiation or magnetic pressure. Helium diffusion may therefore explain the recent observations of globular clusters, which are inconsistent with initially homogeneous helium distribution. [source] Constrained by available raptor hosts and islands: density-dependent reproductive success in red-breasted geeseOIKOS, Issue 3 2003Jouke Prop In this paper we aim to explain the distribution of red-breasted geese Branta ruficollis over different nesting habitats. To be safe from land predators red-breasted goose colonies were restricted to i) islands on rivers, ii) cliffs with peregrine falcons Falco peregrinus, and iii) the close proximity of snowy owl Nyctea scandiaca and rough-legged buzzard Buteo lagopus nests. Among years nest site availability varied by fluctuations in numbers of owls and buzzards in association with cycles in lemming abundance, but the total number of goose nests found in the study area did not vary. The distribution of geese, in combination with data on reproductive success, suggested a despotic mechanism: at cliffs, goose numbers were constant among years with an invariably high reproductive success, whereas large fluctuations in numbers on islands coincided with opposite trends in success. Apparently, geese nesting with owls or buzzards moved to the few islands present in the study area during years when these birds of prey were absent. Consequently, in such years the average density of geese on islands was more than twice as high as at cliff colonies (5.4 and 2.3 pairs per ha of foraging habitat, respectively). Colony size at cliffs may have been restricted by territorial behaviour of the geese, though there is evidence that, additionally, the host falcons also limited the number of nesting geese. Apparently rare in closely related species, we observed a negative density-dependent effect on reproductive success during the nest phase, and attribute this to limited food resources, reinforced by the high frequency of territorial interactions. This leads to the conclusion that, in addition to predation pressure, nesting density is an important agent in the link between lemming cycles and goose breeding success. [source] Microscopic analysis and seasonality of gemma production in the freshwater red alga Hildenbrandia angolensis (Hildenbrandiales, Rhodophyta)PHYCOLOGICAL RESEARCH, Issue 4 2000Alison R. Sherwood SUMMARY The development and release of the unique vegetative propagules of the freshwater encrusting alga Hildenbrandia angolensis Welwitsch ex West et West, gemmae, were studied using several different microscopic and histochemical techniques. In addition, the seasonality of gemma production was monitored bimonthly over a 12-month period in two spring-fed streams in Texas, USA. Gemmae differentiate within the thallus and are subsequently released from the surface of the crust. Release of the gemmae most likely occurs by digestion of surrounding cells, as suggested by the presence of starch granules and lipid globules in the region between the released gemma and the thallus. The initial separation of the gemmae from the thallus occurs from the sides of the gemma or the bottom, or possibly simultaneously. Contrary to previous studies, we have observed that gemma production occurs endogenously within the thallus of freshwater Hildenbrandia, rather than on the surface of the crust in raised structures. Histochemical tests and electron microscopic examination indicate that the cells of the gemmae contain a large amount of floridean starch. The starch granules frequently form rings surrounding the nuclei of both gemma and thallus cells; a feature infrequently reported for florideophyte red algae. Our seasonality investigations indicate that large fluctuations in gemma production occur over 1 year, but at least some gemma production continues year-round in the streams examined. [source] Predicting the low energy landscape of nanoscale silica using interatomic potentialsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2006S. T. BromleyArticle first published online: 18 APR 200 Abstract The energies of 52 of the lowest lying structural isomers of the (SiO2)12 nanocluster are accurately calculated via energy minimisations employing density functional theory (DFT) and also with two silica interatomic potentials (IPs). Of the tested IPs, one was specifically parameterised with respect to small silica nanoclusters, and the other was biased to accurately recover bulk silica properties, although having been applied numerous times to silica nanosystems. The predicted energetic ordering of the nanocluster isomers resulting from the IP optimisations are compared with respect to their deviance from benchmark nanocluster energies from DFT calculations. Although both IPs predict the DFT ground state isomer to be a very low energy cluster and thus are of use in global optimisation studies, large fluctuations in the IP energies of other low lying isomers (relative to the respective DFT energies) shed doubt on their wider applicability to nanoscale silica systems. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Potential Payoff from R&D in the Coconut Industry of North Sulawesi, IndonesiaASIAN ECONOMIC JOURNAL, Issue 1 2010Benjamin Henderson D58; O13; O18 The coconut industry of North Sulawesi, one of the primary coconut-producing provinces of Indonesia, is dominated by a small number of products that are primarily exported overseas. As they only comprise a small share of the global coconut product export market, demand for coconut products from North Sulawesi is generally very elastic. Conversely, the supply of coconuts is highly inelastic, especially in the short to medium term. Hence, small shifts in supply and demand lead to large fluctuations in farmer incomes. In this context, an equilibrium displacement model is used to examine the intra-industry consequences of R&D investments in farm productivity and product development. These investments are assessed in terms of the producer surplus benefits that they generate. [source] Darwinian fitness, evolutionary entropy and directionality theoryBIOESSAYS, Issue 11 2005Klaus Dietz Two recent articles1,2 provide computational and empirical validation of the following analytical fact: the outcome of competition between an invading genotype and that of a resident population is determined by the rate at which the population returns to its original size after a random perturbation. This phenomenon can be quantitatively described in terms of the demographic parameter termed "evolutionary entropy", a measure of the variability in the age at which individuals produce offspring and die. The two articles also validate certain predictions of directionality theory, an evolutionary model that integrates demography and ecology with population genetics. In particular, directionality theory predicts that in populations that spend the greater part of their life cycle in the stationary growth phase, evolution will result in an increase in entropy. These species will be described by a late age of sexual maturity, small progeny sets and a broad reproductive time-span. In populations that undergo large fluctuations in size, however, the evolutionary outcome will be different. When the average size is large, evolution will result in a decrease in entropy,these populations will be described by early age of sexual maturity, large numbers of offspring and narrow reproductive span but when the average size is small, the evolutionary outcome will be random and non-directional. BioEssays 27:1097,1101, 2005. © 2005 Wiley Periodicals, Inc. [source] BUSINESS FAILURES AND MACROECONOMIC FACTORS IN THE UKBULLETIN OF ECONOMIC RESEARCH, Issue 1 2009Jia Liu G33; E42; P11 ABSTRACT We examine the interactions between business failures and macroeconomic aggregates, and specifically the accounts of policy-induced changes in the macroeconomy for the observed fluctuations of UK business failures in the period 1966,2003 using the vector error-correction model (VECM). The results demonstrate that macroeconomic aggregates, i.e., interest rate, credit, profits, inflation and business births, exert differential impacts on business failures both in the short run and in the long run. The study reveals that structural changes in the financial and real sectors during the examined period have made an impact on the way in which the macroeconomy affects business failures. In particular, business failures are increasingly reacting to monetary policy changes in the post-1980 period. Furthermore, the shocks to business failures can generate large fluctuations in macroeconomic aggregates, suggesting the importance of corporate balance sheets in financial stability and economic growth. The paper's findings carry policy implications that are related to the survival of firms in distress and finance-driven business cycles. [source] Non-Gaussian invariant measures for the Majda model of decaying turbulent transportCOMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 9 2001Eric Vanden Eijnden The problem of turbulent transport of a scalar field by a random velocity field is considered. The scalar field amplitude exhibits rare but very large fluctuations whose typical signature are fatter than Gaussian tails for the probability distribution of the scalar. The existence of such large fluctuations is related to clustering phenomena of the Lagrangian paths within the flow. This suggests an approach to turn the large deviation problem for the scalar field into a small deviation, or small ball, problem for some appropriately defined process measuring the spreading with time of the Lagrangian paths. Here, such a methodology is applied to a model proposed by Majda consisting of a white-in-time linear shear flow and some generalizations of it where the velocity field has finite, or even infinite, correlation time. The non-Gaussian invariant measure for the (reduced) scalar field is derived and, in particular, it is shown that the one-point distribution of the scalar has stretched exponential tails, with a stretching exponent depending of the parameters in the model. Different universality classes for the scalar behavior are identified which, all other parameters being kept fixed, display a one-to-one correspondence with a exponent measuring time persistence effects in the velocity field. © 2001 John Wiley & Sons, Inc. [source] | ||||||||||||||||