Cryogenic Calcite: A Morphologic and Isotopic Analog to the ALH84001 Carbonates

NASA Technical Reports Server (NTRS)

Niles, P. B.; Leshin, L. A.; Socki, R. A.; Guan, Y.; Ming, D. W.; Gibson, E. K.

2004-01-01

Martian meteorite ALH84001 carbonates preserve large and variable microscale isotopic compositions, which in some way reflect their formation environment. These measurements show large variations (>20%) in the carbon and oxygen isotopic compositions of the carbonates on a 10-20 micron scale that are correlated with chemical composition. However, the utilization of these data sets for interpreting the formation conditions of the carbonates is complex due to lack of suitable terrestrial analogs and the difficulty of modeling under non-equilibrium conditions. Thus, the mechanisms and processes are largely unknown that create and preserve large microscale isotopic variations in carbonate minerals. Experimental tests of the possible environments and mechanisms that lead to large microscale isotopic variations can help address these concerns. One possible mechanism for creating large carbon isotopic variations in carbonates involves the freezing of water. Carbonates precipitate during extensive CO2 degassing that occurs during the freezing process as the fluid s decreasing volume drives CO2 out. This rapid CO2 degassing results in a kinetic isotopic fractionation where the CO2 gas has a much lighter isotopic composition causing an enrichment of 13C in the remaining dissolved bicarbonate. This study seeks to determine the suitability of cryogenically formed carbonates as analogs to ALH84001 carbonates. Specifically, our objective is to determine how accurately models using equilibrium fractionation factors approximate the isotopic compositions of cryogenically precipitated carbonates. This includes determining the accuracy of applying equilibrium fractionation factors during a kinetic process, and determining how isotopic variations in the fluid are preserved in microscale variations in the precipitated carbonates.

The Impact of Accelerating Faster than Exponential Population Growth on Genetic Variation

PubMed Central

Reppell, Mark; Boehnke, Michael; Zöllner, Sebastian

2014-01-01

Current human sequencing projects observe an abundance of extremely rare genetic variation, suggesting recent acceleration of population growth. To better understand the impact of such accelerating growth on the quantity and nature of genetic variation, we present a new class of models capable of incorporating faster than exponential growth in a coalescent framework. Our work shows that such accelerated growth affects only the population size in the recent past and thus large samples are required to detect the models’ effects on patterns of variation. When we compare models with fixed initial growth rate, models with accelerating growth achieve very large current population sizes and large samples from these populations contain more variation than samples from populations with constant growth. This increase is driven almost entirely by an increase in singleton variation. Moreover, linkage disequilibrium decays faster in populations with accelerating growth. When we instead condition on current population size, models with accelerating growth result in less overall variation and slower linkage disequilibrium decay compared to models with exponential growth. We also find that pairwise linkage disequilibrium of very rare variants contains information about growth rates in the recent past. Finally, we demonstrate that models of accelerating growth may substantially change estimates of present-day effective population sizes and growth times. PMID:24381333

The impact of accelerating faster than exponential population growth on genetic variation.

PubMed

Reppell, Mark; Boehnke, Michael; Zöllner, Sebastian

2014-03-01

Current human sequencing projects observe an abundance of extremely rare genetic variation, suggesting recent acceleration of population growth. To better understand the impact of such accelerating growth on the quantity and nature of genetic variation, we present a new class of models capable of incorporating faster than exponential growth in a coalescent framework. Our work shows that such accelerated growth affects only the population size in the recent past and thus large samples are required to detect the models' effects on patterns of variation. When we compare models with fixed initial growth rate, models with accelerating growth achieve very large current population sizes and large samples from these populations contain more variation than samples from populations with constant growth. This increase is driven almost entirely by an increase in singleton variation. Moreover, linkage disequilibrium decays faster in populations with accelerating growth. When we instead condition on current population size, models with accelerating growth result in less overall variation and slower linkage disequilibrium decay compared to models with exponential growth. We also find that pairwise linkage disequilibrium of very rare variants contains information about growth rates in the recent past. Finally, we demonstrate that models of accelerating growth may substantially change estimates of present-day effective population sizes and growth times.

Frequent pauses in Escherichia coli flagella elongation revealed by single cell real-time fluorescence imaging.

PubMed

Zhao, Ziyi; Zhao, Yifan; Zhuang, Xiang-Yu; Lo, Wei-Chang; Baker, Matthew A B; Lo, Chien-Jung; Bai, Fan

2018-05-14

The bacterial flagellum is a large extracellular protein organelle that extrudes from the cell surface. The flagellar filament is assembled from tens of thousands of flagellin subunits that are exported through the flagellar type III secretion system. Here, we measure the growth of Escherichia coli flagella in real time and find that, although the growth rate displays large variations at similar lengths, it decays on average as flagella lengthen. By tracking single flagella, we show that the large variations in growth rate occur as a result of frequent pauses. Furthermore, different flagella on the same cell show variable growth rates with correlation. Our observations are consistent with an injection-diffusion model, and we propose that an insufficient cytoplasmic flagellin supply is responsible for the pauses in flagellar growth in E. coli.

Asynchronous spore germination in isogenic natural isolates of Saccharomyces paradoxus.

PubMed

Stelkens, Rike B; Miller, Eric L; Greig, Duncan

2016-05-01

Spores from wild yeast isolates often show great variation in the size of colonies they produce, for largely unknown reasons. Here we measure the colonies produced from single spores from six different wild Saccharomyces paradoxus strains. We found remarkable variation in spore colony sizes, even among spores that were genetically identical. Different strains had different amounts of variation in spore colony sizes, and variation was not affected by the number of preceding meioses, or by spore maturation time. We used time-lapse photography to show that wild strains also have high variation in spore germination timing, providing a likely mechanism for the variation in spore colony sizes. When some spores from a laboratory strain make small colonies, or no colonies, it usually indicates a genetic or meiotic fault. Here, we demonstrate that in wild strains spore colony size variation is normal. We discuss and assess potential adaptive and non-adaptive explanations for this variation. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Breeding for resistance in Norway spruce to the root and butt rot fungi Heterobasidion spp

Treesearch

G. Swedjemark; A.K. Borg-Karlson; B. Karlsson

2012-01-01

Results from previous studies of resistance in Norway spruce (Picea abies (L.) Karst.) to the pathogens Heterobasidion spp. show significant genotypic variation in fungal growth and spore susceptibility among Norway spruce clones. The genetic variation and the heritability are large enough for practical breeding purposes and...

[Variations in patient data coding affect hospital standardized mortality ratio (HSMR)].

PubMed

van den Bosch, Wim F; Silberbusch, Joseph; Roozendaal, Klaas J; Wagner, Cordula

2010-01-01

To investigate the impact of coding variations on 'hospital standardized mortality ratio' (HSMR) and to define variation reduction measures. Retrospective, descriptive. We analysed coding variations in HSMR parameters for main diagnosis, urgency of the admission and comorbidity in the national medical registration (LMR) database of admissions in 6 Dutch top clinical hospitals during 2003-2007. More than a quarter of these admission records had been included in the HSMR calculation. Admissions with ICD-9 main diagnosis codes that were excluded from HSMR calculations were investigated for inter-hospital variability and correct exclusion. Variation in coding admission type was signalled by analyzing admission records with diagnoses that had an emergency nature by their title. Variation in the average number of comorbidity diagnoses per admission was determined as an indicator for coding variation. Interviews with coding teams were used to check whether the conclusions of the analysis were correct. Over 165,000 admissions that were excluded from HSMR calculations showed large variability between hospitals. This figure was 40% of all admissions that were included. Of the admissions with a main diagnosis indicating an emergency, 34% to 93% were recorded as an emergency. The average number of comorbidity diagnoses varied between hospitals from 0.9 to 3.0 per admission. Coding of main diagnoses, urgency of admission and comorbidities showed strong inter-hospital variation with a potentially large impact on the HSMR outcomes of the hospitals. Coding variations originated from differences in interpretation of coding rules, differences in coding capacity, quality of patient records and discharge documentation and timely delivery of these.

"Life history space": a multivariate analysis of life history variation in extant and extinct Malagasy lemurs.

PubMed

Catlett, Kierstin K; Schwartz, Gary T; Godfrey, Laurie R; Jungers, William L

2010-07-01

Studies of primate life history variation are constrained by the fact that all large-bodied extant primates are haplorhines. However, large-bodied strepsirrhines recently existed. If we can extract life history information from their skeletons, these species can contribute to our understanding of primate life history variation. This is particularly important in light of new critiques of the classic "fast-slow continuum" as a descriptor of variation in life history profiles across mammals in general. We use established dental histological methods to estimate gestation length and age at weaning for five extinct lemur species. On the basis of these estimates, we reconstruct minimum interbirth intervals and maximum reproductive rates. We utilize principal components analysis to create a multivariate "life history space" that captures the relationships among reproductive parameters and brain and body size in extinct and extant lemurs. Our data show that, whereas large-bodied extinct lemurs can be described as "slow" in some fashion, they also varied greatly in their life history profiles. Those with relatively large brains also weaned their offspring late and had long interbirth intervals. These were not the largest of extinct lemurs. Thus, we distinguish size-related life history variation from variation that linked more strongly to ecological factors. Because all lemur species larger than 10 kg, regardless of life history profile, succumbed to extinction after humans arrived in Madagascar, we argue that large body size increased the probability of extinction independently of reproductive rate. We also provide some evidence that, among lemurs, brain size predicts reproductive rate better than body size. (c) 2010 Wiley-Liss, Inc.

Fast time variations of supernova neutrino signals from 3-dimensional models

DOE PAGES

Lund, Tina; Wongwathanarat, Annop; Janka, Hans -Thomas; ...

2012-11-19

Here, we study supernova neutrino flux variations in the IceCube detector, using 3D models based on a simplified neutrino transport scheme. The hemispherically integrated neutrino emission shows significantly smaller variations compared with our previous study of 2D models, largely because of the reduced activity of the standing accretion shock instability in this set of 3D models which we interpret as a pessimistic extreme. For the studied cases, intrinsic flux variations up to about 100 Hz frequencies could still be detected in a supernova closer than about 2 kpc.

Measuring the benefit of orthophosphate treatment on lead in drinking water.

PubMed

Cardew, P T

2009-03-01

Many water companies are adding low concentrations of orthophosphate to the water supply in order to reduce lead concentrations in drinking water produced from corrosion of lead service pipes. Despite the erratic nature of lead concentrations measured at customer properties it has been possible to quantify the impact of treatment on lead concentrations and thereby quantify the effectiveness of treatment at both a regional and zonal level. This showed that the treatment policy has delivered more than 90 per cent reduction in lead concentrations, and was largely in accordance with theory. Across the region, lead performance and the reduction in lead performance show significant variation. A large part of this variation can be accounted for by variations in the proportion of leaded properties supplied through lead service pipes. Analysis showed that the proportion of particulate lead has also reduced significantly over the last decade. This is attributed to improved mechanical robustness of the corrosion layer caused by changes in its physical structure. This appears to be a very slow process with a natural time-scale of years.

Self-compensating design for reduction of timing and leakage sensitivity to systematic pattern dependent variation

NASA Astrophysics Data System (ADS)

Gupta, Puneet; Kahng, Andrew B.; Kim, Youngmin; Sylvester, Dennis

2006-03-01

Focus is one of the major sources of linewidth variation. CD variation caused by defocus is largely systematic after the layout is finished. In particular, dense lines "smile" through focus while isolated lines "frown" in typical Bossung plots. This well-defined systematic behavior of focus-dependent CD variation allows us to develop a self-compensating design methodology. In this work, we propose a novel design methodology that allows explicit compensation of focus-dependent CD variation, either within a cell (self-compensated cells) or across cells in a critical path (self-compensated design). By creating iso and dense variants for each library cell, we can achieve designs that are more robust to focus variation. Optimization with a mixture of iso and dense cell variants is possible both for area and leakage power, with the latter providing an interesting complement to existing leakage reduction techniques such as dual-Vth. We implement both heuristic and Mixed-Integer Linear Programming (MILP) solution methods to address this optimization, and experimentally compare their results. Our results indicate that designing with a self-compensated cell library incurs ~12% area penalty and ~6% leakage increase over original layouts while compensating for focus-dependent CD variation (i.e., the design meets timing constraints across a large range of focus variation). We observe ~27% area penalty and ~7% leakage increase at the worst-case defocus condition using only single-pitch cells. The area penalty of circuits after using either the heuristic or MILP optimization approach is reduced to ~3% while maintaining timing. We also apply our optimizations to leakage, which traditionally shows very large variability due to its exponential relationship with gate CD. We conclude that a mixed iso/dense library combined with a sensitivity-based optimization approach yields much better area/timing/leakage tradeoffs than using a self-compensated cell library alone. Self-compensated design shows an average of 25% leakage reduction at the worst defocus condition for the benchmark designs that we have studied.

Global properties of the plasma in the outer heliosphere. I - Large-scale structure and evolution

NASA Technical Reports Server (NTRS)

Barnes, A.; Mihalov, J. D.; Gazis, P. R.; Lazarus, A. J.; Belcher, J. W.; Gordon, G. S., Jr.; Mcnutt, R. L., Jr.

1992-01-01

Pioneers 10 and 11, and Voyager 2, have active plasma analyzers as they proceed through heliocentric distances of the order of 30-50 AU, facilitating comparative studies of the global character of the outer solar wind and its variation over the solar cycle. Careful study of these data show that wind ion temperature remains constant beyond 15 AU, and that there may be large-scale variations of temperature with celestial longitude and heliographic latitude. There has thus far been no indication of a heliospheric terminal shock.

Solar luminosity variations and the climate of Mars

NASA Technical Reports Server (NTRS)

Toon, O. B.; Gierasch, P. J.; Sagan, C.

1975-01-01

A simple climatological model of Mars indicates that its climate may be more sensitive to luminosity changes than earth's because of strong positive feedback mechanisms at work on Mars. Mariner 9 photographs of Mars show an abundance of large sinuous channels that point to an epoch of higher atmospheric pressures and abundant liquid water. Such an epoch could have been the result of large-scale solar luminosity variations. The climatological model suggests that other less controversial mechanisms, such as obliquity or polar albedo changes, also could have led to such an epoch.

Tree-ring cellulose exhibits several distinct intramolecular 13C signals

NASA Astrophysics Data System (ADS)

Wieloch, Thomas; Ehlers, Ina; Frank, David; Gessler, Arthur; Grabner, Michael; Yu, Jun; Schleucher, Jürgen

2017-04-01

Stable carbon isotopes are a key tool in biogeosciences. Present applications including compound-specific isotope analysis measure 13C/12C ratios (δ13C) of bulk material or of whole molecules. However, it is well known that primary metabolites also show large intramolecular 13C variation - also called isotopomer variation. This variation reflects 13C fractionation by enzyme reactions and therefore encodes metabolic information. Furthermore, δ13C must be considered an average of the intramolecular 13C distribution. Here we will present (1) methodology to analyse intramolecular 13C distributions of tree-ring cellulose by quantitative 13C NMR (Chaintreau et al., 2013, Anal Chim Acta, 788, 108-113); (2) intramolecular 13C distributions of an annually-resolved tree ring chronology (Pinus nigra, 1961-1995); (3) isotope parameters and terminology for analysis of intramolecular isotope time series; (4) a method for correcting for heterotrophic C redistribution. We will show that the intramolecular 13C distribution of tree-ring cellulose shows large variation, with differences between isotopomers exceeding 10‰Ṫhus, individual 13C isotopomers of cellulose constitute distinct 13C inputs into major global C pools such as wood and soil organic matter. When glucose units with the observed intramolecular 13C pattern are broken down along alternative catabolic pathways, it must be expected that respired CO2 with strongly differing δ13C will be released; indicating that intramolecular 13C variation affects isotope signals of atmosphere-biosphere C exchange fluxes. taking this variation into account will improve modelling of the global C cycle. Furthermore, cluster analysis shows that tree-ring glucose exhibits several independent intramolecular 13C signals, which constitute distinct ecophysiological information channels. Thus, whole-molecule 13C analysis likely misses a large part of the isotope information stored in tree rings. As we have shown for deuterium (Ehlers et al., 2015, PNAS, 112, 15585), intramolecular isotope signals allow tracing plant acclimation over centuries, and intramolecular 13C distributions will also improve our understanding of 13C signatures of global C fluxes.

Spatio-temporal Variations of Characteristic Repeating Earthquake Sequences along the Middle America Trench in Mexico

NASA Astrophysics Data System (ADS)

Dominguez, L. A.; Taira, T.; Hjorleifsdottir, V.; Santoyo, M. A.

2015-12-01

Repeating earthquake sequences are sets of events that are thought to rupture the same area on the plate interface and thus provide nearly identical waveforms. We systematically analyzed seismic records from 2001 through 2014 to identify repeating earthquakes with highly correlated waveforms occurring along the subduction zone of the Cocos plate. Using the correlation coefficient (cc) and spectral coherency (coh) of the vertical components as selection criteria, we found a set of 214 sequences whose waveforms exceed cc≥95% and coh≥95%. Spatial clustering along the trench shows large variations in repeating earthquakes activity. Particularly, the rupture zone of the M8.1, 1985 earthquake shows an almost absence of characteristic repeating earthquakes, whereas the Guerrero Gap zone and the segment of the trench close to the Guerrero-Oaxaca border shows a significantly larger number of repeating earthquakes sequences. Furthermore, temporal variations associated to stress changes due to major shows episodes of unlocking and healing of the interface. Understanding the different components that control the location and recurrence time of characteristic repeating sequences is a key factor to pinpoint areas where large megathrust earthquakes may nucleate and consequently to improve the seismic hazard assessment.

Within and between Population Variation in Epidermal Club Cell Investment in a Freshwater Prey Fish: A Cautionary Tale for Evolutionary Ecologists

PubMed Central

Manek, Aditya K.; Ferrari, Maud C. O.; Pollock, Robyn J.; Vicente, Daniel; Weber, Lynn P.; Chivers, Douglas P.

2013-01-01

Many prey fishes possess large club cells in their epidermis. The role of these cells has garnered considerable attention from evolutionary ecologists. These cells likely form part of the innate immune system of fishes, however, they also have an alarm function, releasing chemical cues that serve to warn nearby conspecifics of danger. Experiments aimed at understanding the selection pressures leading to the evolution of these cells have been hampered by a surprisingly large intraspecific variation in epidermal club cell (ECC) investment. The goal of our current work was to explore the magnitude and nature of this variation in ECC investment. In a field survey, we documented large differences in ECC investment both within and between several populations of minnows. We then tested whether we could experimentally reduce variation in mean ECC number by raising fish under standard laboratory conditions for 4 weeks. Fish from different populations responded very differently to being held under standard laboratory conditions; some populations showed an increase in ECC investment while others remained unchanged. More importantly, we found some evidence that we could reduce within population variation in ECC investment through time, but could not reduce among-population variation in mean ECC investment. Given the large variation we observed in wild fish and our limited ability to converge mean cell number by holding the fish under standard conditions, we caution that future studies may be hard pressed to find subtle effects of various experimental manipulations; this will make elucidating the selection pressures leading to the evolution of the cells challenging. PMID:23469175

Optical characteristics of lightning and thunderstorm currents

NASA Technical Reports Server (NTRS)

Krider, E. P.; Blakeslee, R. J.

1985-01-01

Researchers determined that lightning can be used to determine the diurnal variations of thunderstorms, i.e., storms that produce audible thunder, and that these variations are also in good agreement with diurnal variations in rainfall and convective activity. Measurements of the Maxwell current density, J sub m, under active thunderstorms show that this physical quantity is quasi-steady between lightning discharges and that lightning does not produce large changes in J sub m. Maps of J sub m show contours of iso-current density that are consistent with the locations of radar echos and the locations of where lightning has altered the cloud charge distribution.

Individual Variation in the Late Positive Complex to Semantic Anomalies

PubMed Central

Kos, Miriam; van den Brink, Danielle; Hagoort, Peter

2012-01-01

It is well-known that, within ERP paradigms of sentence processing, semantically anomalous words elicit N400 effects. Less clear, however, is what happens after the N400. In some cases N400 effects are followed by Late Positive Complexes (LPC), whereas in other cases such effects are lacking. We investigated several factors which could affect the LPC, such as contextual constraint, inter-individual variation, and working memory. Seventy-two participants read sentences containing a semantic manipulation (Whipped cream tastes sweet/anxious and creamy). Neither contextual constraint nor working memory correlated with the LPC. Inter-individual variation played a substantial role in the elicitation of the LPC with about half of the participants showing a negative response and the other half showing an LPC. This individual variation correlated with a syntactic ERP as well as an alternative semantic manipulation. In conclusion, our results show that inter-individual variation plays a large role in the elicitation of the LPC and this may account for the diversity in LPC findings in language research. PMID:22973249

Genomic regions controlling shape variation in the first upper molar of the house mouse

PubMed Central

Pantalacci, Sophie; Turner, Leslie M; Steingrimsson, Eirikur; Renaud, Sabrina

2017-01-01

Numerous loci of large effect have been shown to underlie phenotypic variation between species. However, loci with subtle effects are presumably more frequently involved in microevolutionary processes but have rarely been discovered. We explore the genetic basis of shape variation in the first upper molar of hybrid mice between Mus musculus musculus and M. m. domesticus. We performed the first genome-wide association study for molar shape and used 3D surface morphometrics to quantify subtle variation between individuals. We show that many loci of small effect underlie phenotypic variation, and identify five genomic regions associated with tooth shape; one region contained the gene microphthalmia-associated transcription factor Mitf that has previously been associated with tooth malformations. Using a panel of five mutant laboratory strains, we show the effect of the Mitf gene on tooth shape. This is the first report of a gene causing subtle but consistent variation in tooth shape resembling variation in nature. PMID:29091026

Telluric currents: A meeting of theory and observation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boteler, D.H.; Seager, W.H.

Pipe-to-soil (P/S) potential variations resulting from telluric currents have been observed on pipelines in many locations. However, it has never teen clear which parts of a pipeline will experience the worst effects. Two studies were conducted to answer this question. Distributed-source transmission line (DSTL) theory was applied to the problem of modeling geomagnetic induction in pipelines. This theory predicted that the largest P/S potential variations would occur at the ends of the pipeline. The theory also predicted that large P/S potential variations, of opposite sign, should occur on either side of an insulating flange. Independently, an observation program was conductedmore » to determine the change in telluric current P/S potential variations and to design counteractive measures along a pipeline in northern Canada. Observations showed that the amplitude of P/S potential fluctuations had maxima at the northern and southern ends of the pipeline. A further set of recordings around an insulating flange showed large P/S potential variations, of opposite sign, on either side of the flange. Agreement between the observations and theoretical predictions was remarkable. While the observations confirmed the theory, the theory explains how P/S potential variations are produced by telluric currents and provides the basis for design of cathodic protection systems for pipelines that can counteract any adverse telluric effects.« less

The capture of heritable variation for genetic quality through social competition.

PubMed

Wolf, Jason B; Harris, W Edwin; Royle, Nick J

2008-09-01

In theory, females of many species choose mates based on traits that are indicators of male genetic quality. A fundamental question in evolutionary biology is why genetic variation for such indicator traits persists despite strong persistent selection imposed by female preference, which is known as the lek paradox. One potential solution to the lek paradox suggests that the traits that are targets of mate choice should evolve condition-dependent expression and that condition should have a large genetic variance. Condition is expected to exhibit high genetic variance because it is affected by a large number of physiological processes and hence, condition-dependent traits should 'capture' variation contributed by a large number of loci. We suggest that a potentially important cause of variation in condition is competition for limited resources. Here, we discuss a pair of models to analyze the evolutionary genetics of traits affected by success in social competition for resources. We show that competition can contribute to genetic variation of 'competition-dependent' traits that have fundamentally different evolutionary properties than other sources of variation. Competition dependence can make traits honest indicators of genetic quality by revealing the relative competitive ability of males, can provide a component of heritable variation that does not contribute to trait evolution, and can help maintain heritable variation under directional selection. Here we provide a general introduction to the concept of competition dependence and briefly introduce two models to demonstrate the potential evolutionary consequences of competition-dependent trait expression.

Protein degradation rate is the dominant mechanism accounting for the differences in protein abundance of basal p53 in a human breast and colorectal cancer cell line.

PubMed

Lakatos, Eszter; Salehi-Reyhani, Ali; Barclay, Michael; Stumpf, Michael P H; Klug, David R

2017-01-01

We determine p53 protein abundances and cell to cell variation in two human cancer cell lines with single cell resolution, and show that the fractional width of the distributions is the same in both cases despite a large difference in average protein copy number. We developed a computational framework to identify dominant mechanisms controlling the variation of protein abundance in a simple model of gene expression from the summary statistics of single cell steady state protein expression distributions. Our results, based on single cell data analysed in a Bayesian framework, lends strong support to a model in which variation in the basal p53 protein abundance may be best explained by variations in the rate of p53 protein degradation. This is supported by measurements of the relative average levels of mRNA which are very similar despite large variation in the level of protein.

The imprint of surface fluxes and transport on variations in total column carbon dioxide

NASA Astrophysics Data System (ADS)

Keppel-Aleks, G.; Wennberg, P. O.; Washenfelder, R. A.; Wunch, D.; Schneider, T.; Toon, G. C.; Andres, R. J.; Blavier, J.-F.; Connor, B.; Davis, K. J.; Desai, A. R.; Messerschmidt, J.; Notholt, J.; Roehl, C. M.; Sherlock, V.; Stephens, B. B.; Vay, S. A.; Wofsy, S. C.

2011-07-01

New observations of the vertically integrated CO2 mixing ratio, ⟨CO2⟩, from ground-based remote sensing show that variations in ⟨CO2⟩ are primarily determined by large-scale flux patterns. They therefore provide fundamentally different information than observations made within the boundary layer, which reflect the combined influence of large scale and local fluxes. Observations of both ⟨CO2⟩ and CO2 concentrations in the free troposphere show that large-scale spatial gradients induce synoptic-scale temporal variations in ⟨CO2⟩ in the Northern Hemisphere midlatitudes through horizontal advection. Rather than obscure the signature of surface fluxes on atmospheric CO2, these synoptic-scale variations provide useful information that can be used to reveal the meridional flux distribution. We estimate the meridional gradient in ⟨CO2⟩ from covariations in ⟨CO2⟩ and potential temperature, θ, a dynamical tracer, on synoptic timescales to evaluate surface flux estimates commonly used in carbon cycle models. We find that Carnegie Ames Stanford Approach (CASA) biospheric fluxes underestimate both the ⟨CO2⟩ seasonal cycle amplitude throughout the Northern Hemisphere midlatitudes as well as the meridional gradient during the growing season. Simulations using CASA net ecosystem exchange (NEE) with increased and phase-shifted boreal fluxes better reflect the observations. Our simulations suggest that boreal growing season NEE (between 45-65° N) is underestimated by ~40 % in CASA. We describe the implications for this large seasonal exchange on inference of the net Northern Hemisphere terrestrial carbon sink.

The imprint of surface fluxes and transport on variations in total column carbon dioxide

NASA Astrophysics Data System (ADS)

Keppel-Aleks, G.; Wennberg, P. O.; Washenfelder, R. A.; Wunch, D.; Schneider, T.; Toon, G. C.; Andres, R. J.; Blavier, J.-F.; Connor, B.; Davis, K. J.; Desai, A. R.; Messerschmidt, J.; Notholt, J.; Roehl, C. M.; Sherlock, V.; Stephens, B. B.; Vay, S. A.; Wofsy, S. C.

2012-03-01

New observations of the vertically integrated CO2 mixing ratio, ⟨CO2⟩, from ground-based remote sensing show that variations in CO2⟩ are primarily determined by large-scale flux patterns. They therefore provide fundamentally different information than observations made within the boundary layer, which reflect the combined influence of large-scale and local fluxes. Observations of both ⟨CO2⟩ and CO2 concentrations in the free troposphere show that large-scale spatial gradients induce synoptic-scale temporal variations in ⟨CO2⟩ in the Northern Hemisphere midlatitudes through horizontal advection. Rather than obscure the signature of surface fluxes on atmospheric CO2, these synoptic-scale variations provide useful information that can be used to reveal the meridional flux distribution. We estimate the meridional gradient in ⟨CO2⟩ from covariations in ⟨CO2⟩ and potential temperature, θ, a dynamical tracer, on synoptic timescales to evaluate surface flux estimates commonly used in carbon cycle models. We find that simulations using Carnegie Ames Stanford Approach (CASA) biospheric fluxes underestimate both the ⟨CO2⟩ seasonal cycle amplitude throughout the Northern Hemisphere midlatitudes and the meridional gradient during the growing season. Simulations using CASA net ecosystem exchange (NEE) with increased and phase-shifted boreal fluxes better fit the observations. Our simulations suggest that climatological mean CASA fluxes underestimate boreal growing season NEE (between 45-65° N) by ~40%. We describe the implications for this large seasonal exchange on inference of the net Northern Hemisphere terrestrial carbon sink.

Genetic variation of apolipoproteins, diet and other environmental interactions; an updated review.

PubMed

Sotos-Prieto, Mercedes; Peñalvo, José Luis

2013-01-01

This paper summarizes the recent findings from studies investigating the potential environmental modulation of the genetic variation of apolipoprotein genes on metabolic traits. We reviewed nutrigenetic studies evaluating variations on apolipoproteins-related genes and its associated response to nutrients (mostly dietary fatty acids) or any other dietary or environmental component. Most revised research studied single nucleotide polymorphism (SNP) and specific nutrients through small intervention studies, and only few interactions have been replicated in large and independent populations (as in the case of -265T > C SNP in APOA2 gene). Although current knowledge shows that variations on apolipoprotein genes may contribute to the different response on metabolic traits due to dietary interventions, evidence is still scarce and results are inconsistent. Success in this area will require going beyond the limitations of current experimental designs and explore the hypotheses within large populations. Some of these limitations are being covered by the rapidly advance in high-throughput technologies and large scale-genome wide association studies. Copyright © AULA MEDICA EDICIONES 2013. Published by AULA MEDICA. All rights reserved.

Genetic interactions contribute less than additive effects to quantitative trait variation in yeast

PubMed Central

Bloom, Joshua S.; Kotenko, Iulia; Sadhu, Meru J.; Treusch, Sebastian; Albert, Frank W.; Kruglyak, Leonid

2015-01-01

Genetic mapping studies of quantitative traits typically focus on detecting loci that contribute additively to trait variation. Genetic interactions are often proposed as a contributing factor to trait variation, but the relative contribution of interactions to trait variation is a subject of debate. Here we use a very large cross between two yeast strains to accurately estimate the fraction of phenotypic variance due to pairwise QTL–QTL interactions for 20 quantitative traits. We find that this fraction is 9% on average, substantially less than the contribution of additive QTL (43%). Statistically significant QTL–QTL pairs typically have small individual effect sizes, but collectively explain 40% of the pairwise interaction variance. We show that pairwise interaction variance is largely explained by pairs of loci at least one of which has a significant additive effect. These results refine our understanding of the genetic architecture of quantitative traits and help guide future mapping studies. PMID:26537231

Analysis of temporal-longitudinal-latitudinal characteristics in the global ionosphere based on tensor rank-1 decomposition

NASA Astrophysics Data System (ADS)

Lu, Shikun; Zhang, Hao; Li, Xihai; Li, Yihong; Niu, Chao; Yang, Xiaoyun; Liu, Daizhi

2018-03-01

Combining analyses of spatial and temporal characteristics of the ionosphere is of great significance for scientific research and engineering applications. Tensor decomposition is performed to explore the temporal-longitudinal-latitudinal characteristics in the ionosphere. Three-dimensional tensors are established based on the time series of ionospheric vertical total electron content maps obtained from the Centre for Orbit Determination in Europe. To obtain large-scale characteristics of the ionosphere, rank-1 decomposition is used to obtain U^{(1)}, U^{(2)}, and U^{(3)}, which are the resulting vectors for the time, longitude, and latitude modes, respectively. Our initial finding is that the correspondence between the frequency spectrum of U^{(1)} and solar variation indicates that rank-1 decomposition primarily describes large-scale temporal variations in the global ionosphere caused by the Sun. Furthermore, the time lags between the maxima of the ionospheric U^{(2)} and solar irradiation range from 1 to 3.7 h without seasonal dependence. The differences in time lags may indicate different interactions between processes in the magnetosphere-ionosphere-thermosphere system. Based on the dataset displayed in the geomagnetic coordinates, the position of the barycenter of U^{(3)} provides evidence for north-south asymmetry (NSA) in the large-scale ionospheric variations. The daily variation in such asymmetry indicates the influences of solar ionization. The diurnal geomagnetic coordinate variations in U^{(3)} show that the large-scale EIA (equatorial ionization anomaly) variations during the day and night have similar characteristics. Considering the influences of geomagnetic disturbance on ionospheric behavior, we select the geomagnetic quiet GIMs to construct the ionospheric tensor. The results indicate that the geomagnetic disturbances have little effect on large-scale ionospheric characteristics.

Towards Structural Analysis of Audio Recordings in the Presence of Musical Variations

NASA Astrophysics Data System (ADS)

Müller, Meinard; Kurth, Frank

2006-12-01

One major goal of structural analysis of an audio recording is to automatically extract the repetitive structure or, more generally, the musical form of the underlying piece of music. Recent approaches to this problem work well for music, where the repetitions largely agree with respect to instrumentation and tempo, as is typically the case for popular music. For other classes of music such as Western classical music, however, musically similar audio segments may exhibit significant variations in parameters such as dynamics, timbre, execution of note groups, modulation, articulation, and tempo progression. In this paper, we propose a robust and efficient algorithm for audio structure analysis, which allows to identify musically similar segments even in the presence of large variations in these parameters. To account for such variations, our main idea is to incorporate invariance at various levels simultaneously: we design a new type of statistical features to absorb microvariations, introduce an enhanced local distance measure to account for local variations, and describe a new strategy for structure extraction that can cope with the global variations. Our experimental results with classical and popular music show that our algorithm performs successfully even in the presence of significant musical variations.

Controls of bedrock geochemistry on soil and plant nutrients in Southeastern Utah

USGS Publications Warehouse

Neff, J.C.; Reynolds, R.; Sanford, R.L.; Fernandez, D.; Lamothe, P.

2006-01-01

The cold deserts of the Colorado Plateau contain numerous geologically and geochemically distinct sedimentary bedrock types. In the area near Canyonlands National Park in Southeastern Utah, geochemical variation in geologic substrates is related to the depositional environment with higher concentrations of Fe, Al, P, K, and Mg in sediments deposited in alluvial or marine environments and lower concentrations in bedrock derived from eolian sand dunes. Availability of soil nutrients to vegetation is also controlled by the formation of secondary minerals, particularly for P and Ca availability, which, in some geologic settings, appears closely related to variation of CaCO3 and Ca-phosphates in soils. However, the results of this study also indicate that P content is related to bedrock and soil Fe and Al content suggesting that the deposition history of the bedrock and the presence of P-bearing Fe and Al minerals, is important to contemporary P cycling in this region. The relation between bedrock type and exchangeable Mg and K is less clear-cut, despite large variation in bedrock concentrations of these elements. We examined soil nutrient concentrations and foliar nutrient concentration of grasses, shrubs, conifers, and forbs in four geochemically distinct field sites. All four of the functional plant groups had similar proportional responses to variation in soil nutrient availability despite large absolute differences in foliar nutrient concentrations and stoichiometry across species. Foliar P concentration (normalized to N) in particular showed relatively small variation across different geochemical settings despite large variation in soil P availability in these study sites. The limited foliar variation in bedrock-derived nutrients suggests that the dominant plant species in this dryland setting have a remarkably strong capacity to maintain foliar chemistry ratios despite large underlying differences in soil nutrient availability. ?? 2006 Springer Science+Business Media, Inc.

Robust generation of isolated attosecond pulse against the variation of carrier envelope phase of driving laser pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zou Pu; Zeng Zhinan; Zheng Yinghui

2010-11-15

We propose a scheme for generating isolated attosecond pulse (IAP) via high-order harmonic generation in gases using a chirped two-color laser field of multicycle duration. In contrast to previous techniques where the stable carrier-envelope phase (CEP) of the driving laser pulses is a prerequisite for IAP generation, the proposed scheme is robust against the large variation of CEP. We show the generation of IAP with an intensity fluctuation less than 50% and an intensity contrast ratio higher than 5:1 when the CEP shift is as large as 1.35{pi}.

The Rotational Excitation Temperature of the 6614 DIB Carrier

NASA Technical Reports Server (NTRS)

Cami, J.; Salama, F.; Jimenez-Vicente, J.; Galazutdinov, G.; Krelowski, J.

2004-01-01

Analysis of high spectral resolution observations of the lambda6614 DIB line profile show systematic variations in the positions of the peaks in the substructure of the profile. These variations can only be understood in the framework of rotational contours of large molecules, where the variations are caused by changes in the rotational excitation temperature. We show that the rotational excitation temperature for the DIB carrier is of the order 10-40 K - much lower than the gas kinetic temperature - indicating that for this particular DIB carrier angular momentum buildup is not very efficient. The rotational constant indicates that the carrier of this DIB is smaller than previously assumed:7-22 C atoms, depending on the geometry.

Sensitivity of the two-dimensional shearless mixing layer to the initial turbulent kinetic energy and integral length scale

NASA Astrophysics Data System (ADS)

Fathali, M.; Deshiri, M. Khoshnami

2016-04-01

The shearless mixing layer is generated from the interaction of two homogeneous isotropic turbulence (HIT) fields with different integral scales ℓ1 and ℓ2 and different turbulent kinetic energies E1 and E2. In this study, the sensitivity of temporal evolutions of two-dimensional, incompressible shearless mixing layers to the parametric variations of ℓ1/ℓ2 and E1/E2 is investigated. The sensitivity methodology is based on the nonintrusive approach; using direct numerical simulation and generalized polynomial chaos expansion. The analysis is carried out at Reℓ 1=90 for the high-energy HIT region and different integral length scale ratios 1 /4 ≤ℓ1/ℓ2≤4 and turbulent kinetic energy ratios 1 ≤E1/E2≤30 . It is found that the most influential parameter on the variability of the mixing layer evolution is the turbulent kinetic energy while variations of the integral length scale show a negligible influence on the flow field variability. A significant level of anisotropy and intermittency is observed in both large and small scales. In particular, it is found that large scales have higher levels of intermittency and sensitivity to the variations of ℓ1/ℓ2 and E1/E2 compared to the small scales. Reconstructed response surfaces of the flow field intermittency and the turbulent penetration depth show monotonic dependence on ℓ1/ℓ2 and E1/E2 . The mixing layer growth rate and the mixing efficiency both show sensitive dependence on the initial condition parameters. However, the probability density function of these quantities shows relatively small solution variations in response to the variations of the initial condition parameters.

Comparison of Dissolution Similarity Assessment Methods for Products with Large Variations: f2 Statistics and Model-Independent Multivariate Confidence Region Procedure for Dissolution Profiles of Multiple Oral Products.

PubMed

Yoshida, Hiroyuki; Shibata, Hiroko; Izutsu, Ken-Ichi; Goda, Yukihiro

2017-01-01

The current Japanese Ministry of Health Labour and Welfare (MHLW)'s Guideline for Bioequivalence Studies of Generic Products uses averaged dissolution rates for the assessment of dissolution similarity between test and reference formulations. This study clarifies how the application of model-independent multivariate confidence region procedure (Method B), described in the European Medical Agency and U.S. Food and Drug Administration guidelines, affects similarity outcomes obtained empirically from dissolution profiles with large variations in individual dissolution rates. Sixty-one datasets of dissolution profiles for immediate release, oral generic, and corresponding innovator products that showed large variation in individual dissolution rates in generic products were assessed on their similarity by using the f 2 statistics defined in the MHLW guidelines (MHLW f 2 method) and two different Method B procedures, including a bootstrap method applied with f 2 statistics (BS method) and a multivariate analysis method using the Mahalanobis distance (MV method). The MHLW f 2 and BS methods provided similar dissolution similarities between reference and generic products. Although a small difference in the similarity assessment may be due to the decrease in the lower confidence interval for expected f 2 values derived from the large variation in individual dissolution rates, the MV method provided results different from those obtained through MHLW f 2 and BS methods. Analysis of actual dissolution data for products with large individual variations would provide valuable information towards an enhanced understanding of these methods and their possible incorporation in the MHLW guidelines.

Observation of spatial and temporal variations in X-ray bright point emergence patterns. [at solar surface

NASA Technical Reports Server (NTRS)

Golub, L.; Krieger, A. S.; Vaiana, G. S.

1976-01-01

Observations of X-ray bright points (XBP) over a six-month interval in 1973 show significant variations in both the number density of XBP as a function of heliographic longitude and in the full-sun average number of XBP from one rotation to the next. The observed increases in XBP emergence are estimated to be equivalent to several large active regions emerging per day for several months. The number of XBP emerging at high latitudes varies in phase with the low-latitude variation and reaches a maximum approximately simultaneous with a major outbreak of active regions. The quantity of magnetic flux emerging in the form of XBP at high latitudes alone is estimated to be as large as the contribution from all active regions.

Altered trait variability in response to size-selective mortality.

PubMed

Uusi-Heikkilä, Silva; Lindström, Kai; Parre, Noora; Arlinghaus, Robert; Alós, Josep; Kuparinen, Anna

2016-09-01

Changes in trait variability owing to size-selective harvesting have received little attention in comparison with changes in mean trait values, perhaps because of the expectation that phenotypic variability should generally be eroded by directional selection typical for fishing and hunting. We show, however, that directional selection, in particular for large body size, leads to increased body-size variation in experimentally harvested zebrafish (Danio rerio) populations exposed to two alternative feeding environments: ad libitum and temporarily restricted food availability. Trait variation may influence population adaptivity, stability and resilience. Therefore, rather than exerting selection pressures that favour small individuals, our results stress the importance of protecting large ones, as they can harbour a great amount of variation within a population, to manage fish stocks sustainably. © 2016 The Author(s).

Gold nanoparticles for high-throughput genotyping of long-range haplotypes

NASA Astrophysics Data System (ADS)

Chen, Peng; Pan, Dun; Fan, Chunhai; Chen, Jianhua; Huang, Ke; Wang, Dongfang; Zhang, Honglu; Li, You; Feng, Guoyin; Liang, Peiji; He, Lin; Shi, Yongyong

2011-10-01

Completion of the Human Genome Project and the HapMap Project has led to increasing demands for mapping complex traits in humans to understand the aetiology of diseases. Identifying variations in the DNA sequence, which affect how we develop disease and respond to pathogens and drugs, is important for this purpose, but it is difficult to identify these variations in large sample sets. Here we show that through a combination of capillary sequencing and polymerase chain reaction assisted by gold nanoparticles, it is possible to identify several DNA variations that are associated with age-related macular degeneration and psoriasis on significant regions of human genomic DNA. Our method is accurate and promising for large-scale and high-throughput genetic analysis of susceptibility towards disease and drug resistance.

An empirical model of the quiet daily geomagnetic field variation

USGS Publications Warehouse

Yamazaki, Y.; Yumoto, K.; Cardinal, M.G.; Fraser, B.J.; Hattori, P.; Kakinami, Y.; Liu, J.Y.; Lynn, K.J.W.; Marshall, R.; McNamara, D.; Nagatsuma, T.; Nikiforov, V.M.; Otadoy, R.E.; Ruhimat, M.; Shevtsov, B.M.; Shiokawa, K.; Abe, S.; Uozumi, T.; Yoshikawa, A.

2011-01-01

An empirical model of the quiet daily geomagnetic field variation has been constructed based on geomagnetic data obtained from 21 stations along the 210 Magnetic Meridian of the Circum-pan Pacific Magnetometer Network (CPMN) from 1996 to 2007. Using the least squares fitting method for geomagnetically quiet days (Kp ??? 2+), the quiet daily geomagnetic field variation at each station was described as a function of solar activity SA, day of year DOY, lunar age LA, and local time LT. After interpolation in latitude, the model can describe solar-activity dependence and seasonal dependence of solar quiet daily variations (S) and lunar quiet daily variations (L). We performed a spherical harmonic analysis (SHA) on these S and L variations to examine average characteristics of the equivalent external current systems. We found three particularly noteworthy results. First, the total current intensity of the S current system is largely controlled by solar activity while its focus position is not significantly affected by solar activity. Second, we found that seasonal variations of the S current intensity exhibit north-south asymmetry; the current intensity of the northern vortex shows a prominent annual variation while the southern vortex shows a clear semi-annual variation as well as annual variation. Thirdly, we found that the total intensity of the L current system changes depending on solar activity and season; seasonal variations of the L current intensity show an enhancement during the December solstice, independent of the level of solar activity. Copyright 2011 by the American Geophysical Union.

The Nanograv Nine-Year Data Set: Measurement and Analysis of Variations in Dispersion Measures

NASA Technical Reports Server (NTRS)

Jones, M. L.; McLaughlin, M. A.; Lam, M. T.; Cordes, J. M.; Levin, L.; Chatterjee, S.; Arzoumanian, Z.; Crowter, K.; Demorest, P. B.; Dolch, T.;

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, M. L.; McLaughlin, M. A.; Lam, M. T.

We analyze dispersion measure (DM) variations of 37 millisecond pulsars in the nine-year North American Nanohertz Observatory for Gravitational Waves (NANOGrav) data release and constrain the sources of these variations. DM variations can result from a changing distance between Earth and the pulsar, inhomogeneities in the interstellar medium, and solar effects. Variations are significant for nearly all pulsars, with characteristic timescales comparable to or even shorter than the average spacing between observations. Five pulsars have periodic annual variations, 14 pulsars have monotonically increasing or decreasing trends, and 14 pulsars show both effects. Of the four pulsars with linear trends thatmore » have line-of-sight velocity measurements, three are consistent with a changing distance and require an overdensity of free electrons local to the pulsar. Several pulsars show correlations between DM excesses and lines of sight that pass close to the Sun. Mapping of the DM variations as a function of the pulsar trajectory can identify localized interstellar medium features and, in one case, an upper limit to the size of the dispersing region of 4 au. Four pulsars show roughly Kolmogorov structure functions (SFs), and another four show SFs less steep than Kolmogorov. One pulsar has too large an uncertainty to allow comparisons. We discuss explanations for apparent departures from a Kolmogorov-like spectrum, and we show that the presence of other trends and localized features or gradients in the interstellar medium is the most likely cause.« less

Dopa decarboxylase (Ddc) affects variation in Drosophila longevity.

PubMed

De Luca, Maria; Roshina, Nataliya V; Geiger-Thornsberry, Gretchen L; Lyman, Richard F; Pasyukova, Elena G; Mackay, Trudy F C

2003-08-01

Mutational analyses in model organisms have shown that genes affecting metabolism and stress resistance regulate life span, but the genes responsible for variation in longevity in natural populations are largely unidentified. Previously, we mapped quantitative trait loci (QTLs) affecting variation in longevity between two Drosophila melanogaster strains. Here, we show that the longevity QTL in the 36E;38B cytogenetic interval on chromosome 2 contains multiple closely linked QTLs, including the Dopa decarboxylase (Ddc) locus. Complementation tests to mutations show that Ddc is a positional candidate gene for life span in these strains. Linkage disequilibrium (LD) mapping in a sample of 173 alleles from a single population shows that three common molecular polymorphisms in Ddc account for 15.5% of the genetic contribution to variance in life span from chromosome 2. The polymorphisms are in strong LD, and the effects of the haplotypes on longevity suggest that the polymorphisms are maintained by balancing selection. DDC catalyzes the final step in the synthesis of the neurotransmitters, dopamine and serotonin. Thus, these data implicate variation in the synthesis of bioamines as a factor contributing to natural variation in individual life span.

HCMM Heat Capacity Mapping Mission

NASA Technical Reports Server (NTRS)

Jackson, R. D. (Principal Investigator)

1978-01-01

The author has identified the following significant results. Thermal imagery shows a large temperature variation over the 640 acre experimental site. The variation is due to the slope and aspect of the terrain as well as the aircraft flight direction (east-west versus north-south). In spite of these individual temperature differences, mean temperature values from 40 to 640 acre blocks are essentially identical regardless of aircraft flight direction.

The role of tributary mixing in chemical variations at a karst spring, Milandre, Switzerland

NASA Astrophysics Data System (ADS)

Perrin, J.; Jeannin, P.-Y.; Cornaton, F.

2007-01-01

SummarySolute concentration variations during flood events were investigated in a karst aquifer of the Swiss Jura. Observations were made at the spring, and at the three main subterraneous tributaries feeding the spring. A simple transient flow and transport numerical model was able to reproduce chemographs and hydrographs observed at the spring, as a result of a mixing of the concentration and discharge of the respective tributaries. Sensitivity analysis carried out with the model showed that it is possible to produce chemical variations at the spring even if all tributaries have constant (but different for each of them) solute concentrations. This process is called tributary mixing. The good match between observed and modelled curves indicate that, in the phreatic zone, tributary mixing is probably an important process that shapes spring chemographs. Chemical reactions and other mixing components (e.g. from low permeability volumes) have a limited influence. Dissolution-related (calcium, bicarbonate, specific conductance) and pollution-related parameters (nitrate, chloride, potassium) displayed slightly different behaviours: during moderate flood events, the former showed limited variations compared to the latter. During large flood events, both presented chemographs with significant changes. No significant event water participates in moderate flood events and tributary mixing will be the major process shaping chemographs. Variations are greater for parameters with higher spatial variability (e.g. pollution-related). Whereas for large flood events, the contribution of event water becomes significant and influences the chemographs of all the parameters. As a result, spring water vulnerability to an accidental pollution is low during moderate flood events and under base flow conditions. It strongly increases during large flood events, because event water contributes to the spring discharge.

Finding hidden periodic signals in time series - an application to stock prices

NASA Astrophysics Data System (ADS)

O'Shea, Michael

2014-03-01

Data in the form of time series appear in many areas of science. In cases where the periodicity is apparent and the only other contribution to the time series is stochastic in origin, the data can be `folded' to improve signal to noise and this has been done for light curves of variable stars with the folding resulting in a cleaner light curve signal. Stock index prices versus time are classic examples of time series. Repeating patterns have been claimed by many workers and include unusually large returns on small-cap stocks during the month of January, and small returns on the Dow Jones Industrial average (DJIA) in the months June through September compared to the rest of the year. Such observations imply that these prices have a periodic component. We investigate this for the DJIA. If such a component exists it is hidden in a large non-periodic variation and a large stochastic variation. We show how to extract this periodic component and for the first time reveal its yearly (averaged) shape. This periodic component leads directly to the `Sell in May and buy at Halloween' adage. We also drill down and show that this yearly variation emerges from approximately half of the underlying stocks making up the DJIA index.

CNV-seq, a new method to detect copy number variation using high-throughput sequencing.

PubMed

Xie, Chao; Tammi, Martti T

2009-03-06

DNA copy number variation (CNV) has been recognized as an important source of genetic variation. Array comparative genomic hybridization (aCGH) is commonly used for CNV detection, but the microarray platform has a number of inherent limitations. Here, we describe a method to detect copy number variation using shotgun sequencing, CNV-seq. The method is based on a robust statistical model that describes the complete analysis procedure and allows the computation of essential confidence values for detection of CNV. Our results show that the number of reads, not the length of the reads is the key factor determining the resolution of detection. This favors the next-generation sequencing methods that rapidly produce large amount of short reads. Simulation of various sequencing methods with coverage between 0.1x to 8x show overall specificity between 91.7 - 99.9%, and sensitivity between 72.2 - 96.5%. We also show the results for assessment of CNV between two individual human genomes.

Spring-fall asymmetry of substorm strength, geomagnetic activity and solar wind: Implications for semiannual variation and solar hemispheric asymmetry

USGS Publications Warehouse

Marsula, K.; Tanskanen, E.; Love, J.J.

2011-01-01

We study the seasonal variation of substorms, geomagnetic activity and their solar wind drivers in 1993–2008. The number of substorms and substorm mean duration depict an annual variation with maxima in Winter and Summer, respectively, reflecting the annual change of the local ionosphere. In contradiction, substorm mean amplitude, substorm total efficiency and global geomagnetic activity show a dominant annual variation, with equinoctial maxima alternating between Spring in solar cycle 22 and Fall in cycle 23. The largest annual variations were found in 1994 and 2003, in the declining phase of the two cycles when high-speed streams dominate the solar wind. A similar, large annual variation is found in the solar wind driver of substorms and geomagnetic activity, which implies that the annual variation of substorm strength, substorm efficiency and geomagnetic activity is not due to ionospheric conditions but to a hemispherically asymmetric distribution of solar wind which varies from one cycle to another. Our results imply that the overall semiannual variation in global geomagnetic activity has been seriously overestimated, and is largely an artifact of the dominant annual variation with maxima alternating between Spring and Fall. The results also suggest an intimate connection between the asymmetry of solar magnetic fields and some of the largest geomagnetic disturbances, offering interesting new pathways for forecasting disturbances with a longer lead time to the future.

The effect of small variations in profile of airfoils

NASA Technical Reports Server (NTRS)

Ward, Kenneth E

1931-01-01

This report deals with the effect of small variations in ordinates specified by different laboratories for the airfoil section. This study was made in connection with a more general investigation of the effect of small irregularities of the airfoil surface on the aerodynamic characteristics of an airfoil. These tests show that small changes in airfoil contours, resulting from variations in the specified ordinates, have a sufficiently large effect upon the airfoil characteristics to justify the taking of great care in the specification of ordinates for the construction of models.

Large-Scale Atmospheric Teleconnection Patterns Associated with the Interannual Variability of Heatwaves in East Asia and Its Decadal Changes

NASA Astrophysics Data System (ADS)

Choi, N.; Lee, M. I.; Lim, Y. K.; Kim, K. M.

2017-12-01

Heatwave is an extreme hot weather event which accompanies fatal damage to human health. The heatwave has a strong relationship with the large-scale atmospheric teleconnection patterns. In this study, we examine the spatial pattern of heatwave in East Asia by using the EOF analysis and the relationship between heatwave frequency and large-scale atmospheric teleconnection patterns. We also separate the time scale of heatwave frequency as the time scale longer than a decade and the interannual time scale. The long-term variation of heatwave frequency in East Asia shows a linkage with the sea surface temperature (SST) variability over the North Atlantic with a decadal time scale (a.k.a. the Atlantic Multidecadal Oscillation; AMO). On the other hands, the interannual variation of heatwave frequency is linked with the two dominant spatial patterns associated with the large-scale teleconnection patterns mimicking the Scandinavian teleconnection (SCAND-like) pattern and the circumglobal teleconnection (CGT-like) pattern, respectively. It is highlighted that the interannual variation of heatwave frequency in East Asia shows a remarkable change after mid-1990s. While the heatwave frequency was mainly associated with the CGT-like pattern before mid-1990s, the SCAND-like pattern becomes the most dominant one after mid-1990s, making the CGT-like pattern as the second. This study implies that the large-scale atmospheric teleconnection patterns play a key role in developing heatwave events in East Asia. This study further discusses possible mechanisms for the decadal change in the linkage between heatwave frequency and the large-scale teleconnection patterns in East Asia such as early melting of snow cover and/or weakening of East Asian jet stream due to global warming.

Spatial variations in food web structures with alternative stable states: evidence from stable isotope analysis in a large eutrophic lake

NASA Astrophysics Data System (ADS)

Li, Yunkai; Zhang, Yuying; Xu, Jun; Zhang, Shuo

2018-03-01

Food web structures are well known to vary widely among ecosystems. Moreover, many food web studies of lakes have generally attempted to characterize the overall food web structure and have largely ignored internal spatial and environmental variations. In this study, we hypothesize that there is a high degree of spatial heterogeneity within an ecosystem and such heterogeneity may lead to strong variations in environmental conditions and resource availability, in turn resulting in different trophic pathways. Stable carbon and nitrogen isotopes were employed for the whole food web to describe the structure of the food web in different sub-basins within Taihu Lake. This lake is a large eutrophic freshwater lake that has been intensively managed and highly influenced by human activities for more than 50 years. The results show significant isotopic differences between basins with different environmental characteristics. Such differences likely result from isotopic baseline differences combining with a shift in food web structure. Both are related to local spatial heterogeneity in nutrient loading in waters. Such variation should be explicitly considered in future food web studies and ecosystem-based management in this lake ecosystem.

Origins of tropospheric ozone interannual variation over Réunion: A model investigation

NASA Astrophysics Data System (ADS)

Liu, Junhua; Rodriguez, Jose M.; Thompson, Anne M.; Logan, Jennifer A.; Douglass, Anne R.; Olsen, Mark A.; Steenrod, Stephen D.; Posny, Françoise

2016-01-01

Observations from long-term ozonesonde measurements show robust variations and trends in the evolution of ozone in the middle and upper troposphere over Réunion Island (21.1°S, 55.5°E) in June-August. Here we examine possible causes of the observed ozone variation at Réunion Island using hindcast simulations by the stratosphere-troposphere Global Modeling Initiative chemical transport model for 1992-2014, driven by assimilated Modern-Era Retrospective Analysis for Research and Applications meteorological fields. Réunion Island is at the edge of the subtropical jet, a region of strong stratospheric-tropospheric exchange. Our analysis implies that the large interannual variation (IAV) of upper tropospheric ozone over Réunion is driven by the large IAV of the stratospheric influence. The IAV of the large-scale, quasi-horizontal wind patterns also contributes to the IAV of ozone in the upper troposphere. Comparison to a simulation with constant emissions indicates that increasing emissions do not lead to the maximum trend in the middle and upper troposphere over Réunion during austral winter implied by the sonde data. The effects of increasing emission over southern Africa are limited to the lower troposphere near the surface in August-September.

Origins of Tropospheric Ozone Interannual Variation (IAV) over Reunion: A Model Investigation

NASA Technical Reports Server (NTRS)

Liu, Junhua; Rodriguez, Jose M.; Thompson, Anne M.; Logan, Jennifer A.; Douglass, Anne R.; Olsen, Mark A.; Steenrod, Stephen D.; Posny, Francoise

2016-01-01

Observations from long-term ozonesonde measurements show robust variations and trends in the evolution of ozone in the middle and upper troposphere over Reunion Island (21.1 degrees South Latitude, 55.5 degrees East Longitude) in June-August. Here we examine possible causes of the observed ozone variation at Reunion Island using hindcast simulations by the stratosphere-troposphere Global Modeling Initiative chemical transport model for 1992-2014, driven by assimilated Modern-Era Retrospective Analysis for Research and Applications (MERRA) meteorological fields. Reunion Island is at the edge of the subtropical jet, a region of strong stratospheric-tropospheric exchange. Our analysis implies that the large interannual variation (IAV) of upper tropospheric ozone over Reunion is driven by the large IAV of the stratospheric influence. The IAV of the large-scale, quasi-horizontal wind patterns also contributes to the IAV of ozone in the upper troposphere. Comparison to a simulation with constant emissions indicates that increasing emissions do not lead to the maximum trend in the middle and upper troposphere over Reunion during austral winter implied by the sonde data. The effects of increasing emission over southern Africa are limited tothe lower troposphere near the surface in August-September.

Spin-Polarization in Quasi-Magnetic Tunnel Junctions

NASA Astrophysics Data System (ADS)

Xie, Zheng-Wei; Li, Ling

2017-05-01

Spin polarization in ferromagnetic metal/insulator/spin-filter barrier/nonmagnetic metal, referred to as quasi-magnetic tunnel junctions, is studied within the free-electron model. Our results show that large positive or negative spin-polarization can be obtained at high bias in quasi-magnetic tunnel junctions, and within large bias variation regions, the degree of spin-polarization can be linearly tuned by bias. These linear variation regions of spin-polarization with bias are influenced by the barrier thicknesses, barrier heights and molecular fields in the spin-filter (SF) layer. Among them, the variations of thickness and heights of the insulating and SF barrier layers have influence on the value of spin-polarization and the linear variation regions of spin-polarization with bias. However, the variations of molecular field in the SF layer only have influence on the values of the spin-polarization and the influences on the linear variation regions of spin-polarization with bias are slight. Supported by the Key Natural Science Fund of Sichuan Province Education Department under Grant Nos 13ZA0149 and 16ZA0047, and the Construction Plan for Scientific Research Innovation Team of Universities in Sichuan Province under Grant No 12TD008.

Variable sexually dimorphic gene expression in laboratory strains of Drosophila melanogaster.

PubMed

Baker, Dean A; Meadows, Lisa A; Wang, Jing; Dow, Julian At; Russell, Steven

2007-12-10

Wild-type laboratory strains of model organisms are typically kept in isolation for many years, with the action of genetic drift and selection on mutational variation causing lineages to diverge with time. Natural populations from which such strains are established, show that gender-specific interactions in particular drive many aspects of sequence level and transcriptional level variation. Here, our goal was to identify genes that display transcriptional variation between laboratory strains of Drosophila melanogaster, and to explore evidence of gender-biased interactions underlying that variability. Transcriptional variation among the laboratory genotypes studied occurs more frequently in males than in females. Qualitative differences are also apparent to suggest that genes within particular functional classes disproportionately display variation in gene expression. Our analysis indicates that genes with reproductive functions are most often divergent between genotypes in both sexes, however a large proportion of female variation can also be attributed to genes without expression in the ovaries. The present study clearly shows that transcriptional variation between common laboratory strains of Drosophila can differ dramatically due to sexual dimorphism. Much of this variation reflects sex-specific challenges associated with divergent physiological trade-offs, morphology and regulatory pathways operating within males and females.

Optimal fiber design for large capacity long haul coherent transmission [Invited].

PubMed

Hasegawa, Takemi; Yamamoto, Yoshinori; Hirano, Masaaki

2017-01-23

Fiber figure of merit (FOM), derived from the GN-model theory and validated by several experiments, can predict improvement in OSNR or transmission distance using advanced fibers. We review the FOM theory and present design results of optimal fiber for large capacity long haul transmission, showing variation in design results according to system configuration.

The Diversity Present in 5140 Human Mitochondrial Genomes

PubMed Central

Pereira, Luísa; Freitas, Fernando; Fernandes, Verónica; Pereira, Joana B.; Costa, Marta D.; Costa, Stephanie; Máximo, Valdemar; Macaulay, Vincent; Rocha, Ricardo; Samuels, David C.

2009-01-01

We analyzed the current status (as of the end of August 2008) of human mitochondrial genomes deposited in GenBank, amounting to 5140 complete or coding-region sequences, in order to present an overall picture of the diversity present in the mitochondrial DNA of the global human population. To perform this task, we developed mtDNA-GeneSyn, a computer tool that identifies and exhaustedly classifies the diversity present in large genetic data sets. The diversity observed in the 5140 human mitochondrial genomes was compared with all possible transitions and transversions from the standard human mitochondrial reference genome. This comparison showed that tRNA and rRNA secondary structures have a large effect in limiting the diversity of the human mitochondrial sequences, whereas for the protein-coding genes there is a bias toward less variation at the second codon positions. The analysis of the observed amino acid variations showed a tolerance of variations that convert between the amino acids V, I, A, M, and T. This defines a group of amino acids with similar chemical properties that can interconvert by a single transition. PMID:19426953

Local Energies and Energy Fluctuations — Applied to the High Entropy Alloy CrFeCoNi

NASA Astrophysics Data System (ADS)

Fukushima, Tetsuya; Katayama-Yoshida, Hiroshi; Sato, Kazunori; Ogura, Masako; Zeller, Rudolf; Dederichs, Peter H.

2017-11-01

High entropy alloys show a variety of fascinating properties like high hardness, wear resistance, corrosion resistance, etc. They are random solid solutions of many components with rather high concentrations. We perform ab-initio calculations for the high entropy alloy CrFeCoNi, which equal concentration of 25% for each element. By the KKRnano program package, which is based on an order-N screened Korringa-Kohn-Rostoker Green's function method, we consider a face-centered cubic (FCC) supercell with 1372 randomly distributed elements, and in addition also smaller supercells with 500 and 256 atoms. It is found from our calculations that the local moments of the Cr atoms show a large environmental variation, ranging from -1.70 μB to +1.01 μB with an average of about -0.51 μB. We present a new method to calculate "local energies" of all atoms. This is based on the partitioning of the whole space into Voronoi cells and allows to calculate the energetic contribution of each atomic cell to the total energy of the supercell. The supercell calculations show very large variations of the local energies, analogous to the variations of the local moments. This shows that the random solid solution is not stable and has a tendency to form an L12-structure with the Cr-atoms ordered at the corner of the cube and the elements Fe, Co, and Ni randomly distributed on the three other FCC sublattices. For this structure the variation of the local moments are much smaller.

The implications of variable remigration intervals for the assessment of population size in marine turtles.

PubMed

Hays, G C

2000-09-21

Sea turtles nest on sandy beaches and tend to show high fidelity to specific nesting areas, but, despite this fidelity, the inter-annual variation in nesting numbers may be large. This variation may reflect the fact that turtles do not usually nest in consecutive years. Here, theoretical models are developed in which the interval between successive nesting years (the remigration interval) reflects conditions encountered on the feeding grounds, with good feeding years leading to a reduction in the remigration interval and vice versa. These simple models produce high levels of inter-annual variation in nesting numbers with, on occasion, almost no turtles nesting in some years even when the population is large and stable. The implications for assessing the size of sea turtle populations are considered. Copyright 2000 Academic Press.

Identifying tagging SNPs for African specific genetic variation from the African Diaspora Genome

PubMed Central

Johnston, Henry Richard; Hu, Yi-Juan; Gao, Jingjing; O’Connor, Timothy D.; Abecasis, Gonçalo R.; Wojcik, Genevieve L; Gignoux, Christopher R.; Gourraud, Pierre-Antoine; Lizee, Antoine; Hansen, Mark; Genuario, Rob; Bullis, Dave; Lawley, Cindy; Kenny, Eimear E.; Bustamante, Carlos; Beaty, Terri H.; Mathias, Rasika A.; Barnes, Kathleen C.; Qin, Zhaohui S.; Preethi Boorgula, Meher; Campbell, Monica; Chavan, Sameer; Ford, Jean G.; Foster, Cassandra; Gao, Li; Hansel, Nadia N.; Horowitz, Edward; Huang, Lili; Ortiz, Romina; Potee, Joseph; Rafaels, Nicholas; Ruczinski, Ingo; Scott, Alan F.; Taub, Margaret A.; Vergara, Candelaria; Levin, Albert M.; Padhukasahasram, Badri; Williams, L. Keoki; Dunston, Georgia M.; Faruque, Mezbah U.; Gietzen, Kimberly; Deshpande, Aniket; Grus, Wendy E.; Locke, Devin P.; Foreman, Marilyn G.; Avila, Pedro C.; Grammer, Leslie; Kim, Kwang-Youn A.; Kumar, Rajesh; Schleimer, Robert; De La Vega, Francisco M.; Shringarpure, Suyash S.; Musharoff, Shaila; Burchard, Esteban G.; Eng, Celeste; Hernandez, Ryan D.; Pino-Yanes, Maria; Torgerson, Dara G.; Szpiech, Zachary A.; Torres, Raul; Nicolae, Dan L.; Ober, Carole; Olopade, Christopher O; Olopade, Olufunmilayo; Oluwole, Oluwafemi; Arinola, Ganiyu; Song, Wei; Correa, Adolfo; Musani, Solomon; Wilson, James G.; Lange, Leslie A.; Akey, Joshua; Bamshad, Michael; Chong, Jessica; Fu, Wenqing; Nickerson, Deborah; Reiner, Alexander; Hartert, Tina; Ware, Lorraine B.; Bleecker, Eugene; Meyers, Deborah; Ortega, Victor E.; Maul, Pissamai; Maul, Trevor; Watson, Harold; Ilma Araujo, Maria; Riccio Oliveira, Ricardo; Caraballo, Luis; Marrugo, Javier; Martinez, Beatriz; Meza, Catherine; Ayestas, Gerardo; Francisco Herrera-Paz, Edwin; Landaverde-Torres, Pamela; Erazo, Said Omar Leiva; Martinez, Rosella; Mayorga, Alvaro; Mayorga, Luis F.; Mejia-Mejia, Delmy-Aracely; Ramos, Hector; Saenz, Allan; Varela, Gloria; Marina Vasquez, Olga; Ferguson, Trevor; Knight-Madden, Jennifer; Samms-Vaughan, Maureen; Wilks, Rainford J.; Adegnika, Akim; Ateba-Ngoa, Ulysse; Yazdanbakhsh, Maria

2017-01-01

A primary goal of The Consortium on Asthma among African-ancestry Populations in the Americas (CAAPA) is to develop an ‘African Diaspora Power Chip’ (ADPC), a genotyping array consisting of tagging SNPs, useful in comprehensively identifying African specific genetic variation. This array is designed based on the novel variation identified in 642 CAAPA samples of African ancestry with high coverage whole genome sequence data (~30× depth). This novel variation extends the pattern of variation catalogued in the 1000 Genomes and Exome Sequencing Projects to a spectrum of populations representing the wide range of West African genomic diversity. These individuals from CAAPA also comprise a large swath of the African Diaspora population and incorporate historical genetic diversity covering nearly the entire Atlantic coast of the Americas. Here we show the results of designing and producing such a microchip array. This novel array covers African specific variation far better than other commercially available arrays, and will enable better GWAS analyses for researchers with individuals of African descent in their study populations. A recent study cataloging variation in continental African populations suggests this type of African-specific genotyping array is both necessary and valuable for facilitating large-scale GWAS in populations of African ancestry. PMID:28429804

The functional spectrum of low-frequency coding variation.

PubMed

Marth, Gabor T; Yu, Fuli; Indap, Amit R; Garimella, Kiran; Gravel, Simon; Leong, Wen Fung; Tyler-Smith, Chris; Bainbridge, Matthew; Blackwell, Tom; Zheng-Bradley, Xiangqun; Chen, Yuan; Challis, Danny; Clarke, Laura; Ball, Edward V; Cibulskis, Kristian; Cooper, David N; Fulton, Bob; Hartl, Chris; Koboldt, Dan; Muzny, Donna; Smith, Richard; Sougnez, Carrie; Stewart, Chip; Ward, Alistair; Yu, Jin; Xue, Yali; Altshuler, David; Bustamante, Carlos D; Clark, Andrew G; Daly, Mark; DePristo, Mark; Flicek, Paul; Gabriel, Stacey; Mardis, Elaine; Palotie, Aarno; Gibbs, Richard

2011-09-14

Rare coding variants constitute an important class of human genetic variation, but are underrepresented in current databases that are based on small population samples. Recent studies show that variants altering amino acid sequence and protein function are enriched at low variant allele frequency, 2 to 5%, but because of insufficient sample size it is not clear if the same trend holds for rare variants below 1% allele frequency. The 1000 Genomes Exon Pilot Project has collected deep-coverage exon-capture data in roughly 1,000 human genes, for nearly 700 samples. Although medical whole-exome projects are currently afoot, this is still the deepest reported sampling of a large number of human genes with next-generation technologies. According to the goals of the 1000 Genomes Project, we created effective informatics pipelines to process and analyze the data, and discovered 12,758 exonic SNPs, 70% of them novel, and 74% below 1% allele frequency in the seven population samples we examined. Our analysis confirms that coding variants below 1% allele frequency show increased population-specificity and are enriched for functional variants. This study represents a large step toward detecting and interpreting low frequency coding variation, clearly lays out technical steps for effective analysis of DNA capture data, and articulates functional and population properties of this important class of genetic variation.

Individual variation in growth in sea cucumber Apostichopus japonicus (Selenck) housed individually

NASA Astrophysics Data System (ADS)

Liang, Miao; Dong, Shuanglin; Gao, Qinfeng; Wang, Fang; Tian, Xiangli

2010-09-01

The exceptionally large individual growth variation has been previously recognized in several sea cucumber cohorts. However, there is a lack of information regarding the mechanism of such individual differences. In this study, the sea cucumber Apostichopus japonicus (Selenka) was reared individually in order to eliminate possible effects of social interaction, stocking density, etc. The results showed that there were substantial differences in growth among the sea cucumber individuals during the 100-day experiment. The special growth rate of the sea cucumber individuals differed by up to three folds (from 0.40% to 1.01%), and the coefficient of variation in body weight increased from 12.04% to 40.51%. The final wet body weight, food intake and food conversion efficiency for each sea cucumber were generally positively correlated with their initial wet body weight ( P<0.05). Energy budget of the animals showed that the food energy spent on respiration was much greater (about four folds) but energy deposited for growth was much less for (initially) smaller than for larger A. japonicus. The present result implies that there are obvious genetic differences among the sea cucumber individuals, largely accounting for the individual growth variation of the cohort sea cucumber. These results will provide some basic data for promoting selective breeding and farming of the sea cucumber.

The plasma environment, charge state, and currents of Saturn's C and D rings

NASA Technical Reports Server (NTRS)

Wilson, G. R.

1991-01-01

The charge state and associated currents of Saturn's C an D rings are studied by modeling the flow of ionospheric plasma from the mid- to low-latitude ionosphere to the vicinity of the rings. It is found that the plasma density near the C and D rings, at a given radial location, will experience a one to two order of magnitude diurnal variation. The surface charge density (SCD) of these rings can show significant radial and azimuthal variations due mainly to variation in the plasma density. The SCD also depends on structural features of the rings such as thickness and the nature of the particle size distribution. The associated azimuthal currents carried by these rings also show large diurnal variations resulting in field-aligned currents which close in the ionosphere. The resulting ionospheric electric field will probably not produce a significant amount of plasma convection in the topside ionosphere and inner plasmasphere.

Emergence of intercolonial variation in termite shelter tube patterns and prediction of its underlying mechanism

PubMed Central

2015-01-01

Building behaviours occur in various organisms from bacteria to humans. Social insects build various structures such as large nests and underground galleries, achieved by self-organization. Structures built by social insects have recently been demonstrated to vary widely in size and shape within a species, even under the same environmental conditions. However, little is known about how intraspecific variation in structures emerges from collective behaviours. Here we show that the colony variation of structures can be generated by simply changing two behavioural parameters of group members, even with the same building algorithm. Our laboratory experiment of termite shelter tube construction demonstrated clear intercolonial variation, and a two-dimensional lattice model showed that it can be attributed to the extent of positive feedback and the number of individuals engaged in building. This study contributes to explaining the great diversity of structures emerging from collective building in social insects. PMID:26715997

High individual variation in pheromone production by tree-killing bark beetles (Coleoptera: Curculionidae: Scolytinae)

NASA Astrophysics Data System (ADS)

Pureswaran, Deepa S.; Sullivan, Brian T.; Ayres, Matthew P.

2008-01-01

Aggregation via pheromone signalling is essential for tree-killing bark beetles to overcome tree defenses and reproduce within hosts. Pheromone production is a trait that is linked to fitness, so high individual variation is paradoxical. One explanation is that the technique of measuring static pheromone pools overestimates true variation among individuals. An alternative hypothesis is that aggregation behaviour dilutes the contribution of individuals to the trait under selection and reduces the efficacy of natural selection on pheromone production by individuals. We compared pheromone measurements from traditional hindgut extractions of female southern pine beetles with those obtained by aerating individuals till they died. Aerations showed greater total pheromone production than hindgut extractions, but coefficients of variation (CV) remained high (60-182%) regardless of collection technique. This leaves the puzzle of high variation unresolved. A novel but simple explanation emerges from considering bark beetle aggregation behaviour. The phenotype visible to natural selection is the collective pheromone plume from hundreds of colonisers. The influence of a single beetle on this plume is enhanced by high variation among individuals but constrained by large group sizes. We estimated the average contribution of an individual to the pheromone plume across a range of aggregation sizes and showed that large aggregation sizes typical in mass attacks limit the potential of natural selection because each individual has so little effect on the overall plume. Genetic variation in pheromone production could accumulate via mutation and recombination, despite strong effects of the pheromone plume on the fitness of individuals within the aggregation. Thus, aggregation behaviour, by limiting the efficacy of natural selection, can allow the persistence of extreme phenotypes in nature.

Macrophytes shape trophic niche variation among generalist fishes.

PubMed

Vejříková, Ivana; Eloranta, Antti P; Vejřík, Lukáš; Šmejkal, Marek; Čech, Martin; Sajdlová, Zuzana; Frouzová, Jaroslava; Kiljunen, Mikko; Peterka, Jiří

2017-01-01

Generalist species commonly have a fundamental role in ecosystems as they can integrate spatially distinct habitats and food-web compartments, as well as control the composition, abundance and behavior of organisms at different trophic levels. Generalist populations typically consist of specialized individuals, but the potential for and hence degree of individual niche variation can be largely determined by habitat complexity. We compared individual niche variation within three generalist fishes between two comparable lakes in the Czech Republic differing in macrophyte cover, i.e. macrophyte-rich Milada and macrophyte-poor Most. We tested the hypothesis that large individual niche variation among generalist fishes is facilitated by the presence of macrophytes, which provides niches and predation shelter for fish and their prey items. Based on results from stable nitrogen (δ15N) and carbon (δ13C) isotopic mixing models, perch (Perca fluviatilis L.) and rudd (Scardinius erythrophthalmus (L.)) showed larger individual variation (i.e., variance) in trophic position in Milada as compared to Most, whereas no significant between-lake differences were observed for roach (Rutilus rutilus (L.)). Contrary to our hypothesis, all the three species showed significantly lower individual variation in the relative reliance on littoral food resources in Milada than in Most. Rudd relied significantly more whereas perch and roach relied less on littoral food resources in Milada than in Most, likely due to prevalent herbivory by rudd and prevalent zooplanktivory by perch and roach in the macrophyte-rich Milada as compared to macrophyte-poor Most. Our study demonstrates how the succession of macrophyte vegetation, via its effects on the physical and biological complexity of the littoral zone and on the availability of small prey fish and zooplankton, can strongly influence individual niche variation among generalist fishes with different ontogenetic trajectories, and hence the overall food-web structures in lake ecosystems.

Multiply to conquer: Copy number variations at Ppd-B1 and Vrn-A1 facilitate global adaptation in wheat.

PubMed

Würschum, Tobias; Boeven, Philipp H G; Langer, Simon M; Longin, C Friedrich H; Leiser, Willmar L

2015-07-29

Copy number variation was found to be a frequent type of DNA polymorphism in the human genome often associated with diseases but its importance in crops and the effects on agronomic traits are still largely unknown. Here, we employed a large worldwide panel of 1110 winter wheat varieties to assess the frequency and the geographic distribution of copy number variants at the Photoperiod-B1 (Ppd-B1) and the Vernalization-A1 (Vrn-A1) loci as well as their effects on flowering time under field conditions. We identified a novel four copy variant of Vrn-A1 and based on the phylogenetic relationships among the lines show that the higher copy variants at both loci are likely to have arisen independently multiple times. In addition, we found that the frequency of the different copy number variants at both loci reflects the environmental conditions in the varieties' region of origin and based on multi-location field trials show that Ppd-B1 copy number has a substantial effect on the fine-tuning of flowering time. In conclusion, our results show the importance of copy number variation at Ppd-B1 and Vrn-A1 for the global adaptation of wheat making it a key factor for wheat success in a broad range of environments and in a wider context substantiate the significant role of copy number variation in crops.

An ensemble constrained variational analysis of atmospheric forcing data and its application to evaluate clouds in CAM5: Ensemble 3DCVA and Its Application

DOE PAGES

Tang, Shuaiqi; Zhang, Minghua; Xie, Shaocheng

2016-01-05

Large-scale atmospheric forcing data can greatly impact the simulations of atmospheric process models including Large Eddy Simulations (LES), Cloud Resolving Models (CRMs) and Single-Column Models (SCMs), and impact the development of physical parameterizations in global climate models. This study describes the development of an ensemble variationally constrained objective analysis of atmospheric large-scale forcing data and its application to evaluate the cloud biases in the Community Atmospheric Model (CAM5). Sensitivities of the variational objective analysis to background data, error covariance matrix and constraint variables are described and used to quantify the uncertainties in the large-scale forcing data. Application of the ensemblemore » forcing in the CAM5 SCM during March 2000 intensive operational period (IOP) at the Southern Great Plains (SGP) of the Atmospheric Radiation Measurement (ARM) program shows systematic biases in the model simulations that cannot be explained by the uncertainty of large-scale forcing data, which points to the deficiencies of physical parameterizations. The SCM is shown to overestimate high clouds and underestimate low clouds. These biases are found to also exist in the global simulation of CAM5 when it is compared with satellite data.« less

An ensemble constrained variational analysis of atmospheric forcing data and its application to evaluate clouds in CAM5: Ensemble 3DCVA and Its Application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Shuaiqi; Zhang, Minghua; Xie, Shaocheng

Large-scale atmospheric forcing data can greatly impact the simulations of atmospheric process models including Large Eddy Simulations (LES), Cloud Resolving Models (CRMs) and Single-Column Models (SCMs), and impact the development of physical parameterizations in global climate models. This study describes the development of an ensemble variationally constrained objective analysis of atmospheric large-scale forcing data and its application to evaluate the cloud biases in the Community Atmospheric Model (CAM5). Sensitivities of the variational objective analysis to background data, error covariance matrix and constraint variables are described and used to quantify the uncertainties in the large-scale forcing data. Application of the ensemblemore » forcing in the CAM5 SCM during March 2000 intensive operational period (IOP) at the Southern Great Plains (SGP) of the Atmospheric Radiation Measurement (ARM) program shows systematic biases in the model simulations that cannot be explained by the uncertainty of large-scale forcing data, which points to the deficiencies of physical parameterizations. The SCM is shown to overestimate high clouds and underestimate low clouds. These biases are found to also exist in the global simulation of CAM5 when it is compared with satellite data.« less

[An alternative continence mechanism for continent catheterisable micturation].

PubMed

Honeck, P; Alken, P

2010-01-01

The creation of a stable, reliable, continent and easily catheterisable continence mechanism is an essential prerequisite for the construction of a continent cutaneous urinary reservoir. Although a substantial number of surgical methods has been described, construction is still a complex surgical procedure. The aim of this study was the evaluation of a new method for a continence mechanism using stapled small or large intestine. Small and large pig intestine was used for construction. For stapling the tube a 3 cm or 6 cm double row stapling system was used. Two variations using small and large intestine segments were constructed (IL 1, COL 1, COL 2). A 3 or 6 cm long stapler line was placed alongside a 12 Fr catheter positioned at the antimesenterial side creating a partially two-luminal segment. The open end of the non-catheterised lumen and the opposite intestinal end were closed by continuous sutures. The created tube was then embedded into the pouch. Pressure evaluation was performed for each variation. Intermittent external manual compression was used to simulate sudden pressure exposure. Construction times for the IL 1 and COL 1 variations were 10 +/- 1.5 min and 6.2 +/- 1.3 min for COL 2. All variations showed no leakage during filling or external compression. The maximum capacity was lower for the IL 1 compared to the COL variation. The maximum pressure levels reached did not differ significantly. The described technique is an easy and fast method to construct a continent and easy to catheterize continence mechanism using small or large intestine.

The African Genome Variation Project shapes medical genetics in Africa

PubMed Central

Gurdasani, Deepti; Carstensen, Tommy; Tekola-Ayele, Fasil; Pagani, Luca; Tachmazidou, Ioanna; Hatzikotoulas, Konstantinos; Karthikeyan, Savita; Iles, Louise; Pollard, Martin O.; Choudhury, Ananyo; Ritchie, Graham R. S.; Xue, Yali; Asimit, Jennifer; Nsubuga, Rebecca N.; Young, Elizabeth H.; Pomilla, Cristina; Kivinen, Katja; Rockett, Kirk; Kamali, Anatoli; Doumatey, Ayo P.; Asiki, Gershim; Seeley, Janet; Sisay-Joof, Fatoumatta; Jallow, Muminatou; Tollman, Stephen; Mekonnen, Ephrem; Ekong, Rosemary; Oljira, Tamiru; Bradman, Neil; Bojang, Kalifa; Ramsay, Michele; Adeyemo, Adebowale; Bekele, Endashaw; Motala, Ayesha; Norris, Shane A.; Pirie, Fraser; Kaleebu, Pontiano; Kwiatkowski, Dominic; Tyler-Smith, Chris; Rotimi, Charles; Zeggini, Eleftheria; Sandhu, Manjinder S.

2014-01-01

Given the importance of Africa to studies of human origins and disease susceptibility, detailed characterisation of African genetic diversity is needed. The African Genome Variation Project (AGVP) provides a resource to help design, implement and interpret genomic studies in sub-Saharan Africa (SSA) and worldwide. The AGVP represents dense genotypes from 1,481 and whole genome sequences (WGS) from 320 individuals across SSA. Using this resource, we find novel evidence of complex, regionally distinct hunter-gatherer and Eurasian admixture across SSA. We identify new loci under selection, including for malaria and hypertension. We show that modern imputation panels can identify association signals at highly differentiated loci across populations in SSA. Using WGS, we show further improvement in imputation accuracy supporting efforts for large-scale sequencing of diverse African haplotypes. Finally, we present an efficient genotype array design capturing common genetic variation in Africa, showing for the first time that such designs are feasible. PMID:25470054

Geographic variability of adherence to occupational injury treatment guidelines.

PubMed

Trujillo, Antonio J; Heins, Sara E; Anderson, Gerard F; Castillo, Renan C

2014-12-01

To determine the geographic variability and relationship between six occupational injury practice guidelines. Guidelines were developed by an expert panel and evaluated using workers' compensation claims data from a large, national insurance company (1999 to 2010). Percentage compliance for each guideline was adjusted for age and sex using linear regression and mapped by hospital referral region. Regions with the lowest compliance were identified, and correlations between guidelines were calculated. Compliance to the unnecessary home care guideline showed the lowest geographic variation (interquartile range: 97.3 to 99.0), and inappropriate shoulder bracing showed the highest variation (interquartile range: 77.7 to 90.8). Correlation between the guidelines was weak and not always positive. Different guidelines showed different degrees of geographic variation. Lack of correlation between guidelines suggests that these indicators were not associated with a single underlying health care quality or patient severity construct.

Relative Contributions of Coronal Mass Ejections and High-speed Streams to the Long-term Variation of Annual Geomagnetic Activity: Solar Cycle Variation and Latitudinal Differences

NASA Astrophysics Data System (ADS)

Holappa, L.; Mursula, K.

2017-12-01

Coronal mass ejections (CMEs) and high-speed solar wind streams (HSSs) are the most important large-scale solar wind structures driving geomagnetic activity. It is well known that CMEs cause the strongest geomagnetic storms, while HSSs drive mainly moderate or small storms. Here we study the spatial-temporal distribution of geomagnetic activity at annual resolution using local geomagnetic indices from a wide range of latitudes in 1966-2014. We show that the overall contribution of HSSs to geomagnetic activity exceeds that of CMEs at all latitudes. Only in a few sunspot maximum years CMEs have a comparable contribution to HSSs. While the relative contribution of HSSs maximizes at high latitudes, the relative contribution of CMEs maximizes at subauroral and low latitudes. We show that this is related to different latitudinal distribution of CME and HSS-driven substorms. We also show that the contributions of CMEs and HSSs to annual geomagnetic activity are highly correlated with the intensity of the interplanetary magnetic field and the solar wind speed, respectively. Thus, a very large fraction of the long-term variability in annual geomagnetic activity is described only by the variation of IMF strength and solar wind speed.

Variation of bar-press duration: where do new responses come from?

PubMed

Roberts, Seth; Gharib, Afshin

2006-06-01

Instrumental learning involves both variation and selection: variation of what the animal does, and selection by reward from among the variation. Four experiments with rats suggested a rule about how variation is controlled by recent events. Experiment 1 used the peak procedure. Measurements of bar-press durations showed a sharp increase in mean duration after the time that food was sometimes given. The increase was triggered by the omission of expected food. Our first explanation of the increase was that it was a frustration effect. Experiment 2 tested this explanation with a procedure in which the first response of a trial usually produced food, ending the trial. In Experiment 2, unlike Experiment 1, omission of expected food did not produce a large increase in bar-press duration, which cast doubt on the frustration explanation. Experiments 3 and 4 tested an alternative explanation: a decrease in expectation of reward increases variation. Both used two signals associated with different probabilities of reward. Bar presses were more variable in duration during the signal with the lower probability of reward, supporting this alternative. These experiments show how variation can be studied with ordinary equipment and responses.

Spring-fall asymmetry of substorm strength, geomagnetic activity and solar wind: Implications for semiannual variation and solar hemispheric asymmetry

USGS Publications Warehouse

Mursula, K.; Tanskanen, E.; Love, J.J.

2011-01-01

We study the seasonal variation of substorms, geomagnetic activity and their solar wind drivers in 1993-2008. The number of substorms and substorm mean duration depict an annual variation with maxima in Winter and Summer, respectively, reflecting the annual change of the local ionosphere. In contradiction, substorm mean amplitude, substorm total efficiency and global geomagnetic activity show a dominant annual variation, with equinoctial maxima alternating between Spring in solar cycle 22 and Fall in cycle 23. The largest annual variations were found in 1994 and 2003, in the declining phase of the two cycles when high-speed streams dominate the solar wind. A similar, large annual variation is found in the solar wind driver of substorms and geomagnetic activity, which implies that the annual variation of substorm strength, substorm efficiency and geomagnetic activity is not due to ionospheric conditions but to a hemispherically asymmetric distribution of solar wind which varies from one cycle to another. Our results imply that the overall semiannual variation in global geomagnetic activity has been seriously overestimated, and is largely an artifact of the dominant annual variation with maxima alternating between Spring and Fall. The results also suggest an intimate connection between the asymmetry of solar magnetic fields and some of the largest geomagnetic disturbances, offering interesting new pathways for forecasting disturbances with a longer lead time to the future. Copyright ?? 2011 by the American Geophysical Union.

Average diurnal variation of summer lightning over the Florida peninsula

NASA Technical Reports Server (NTRS)

Maier, L. M.; Krider, E. P.; Maier, M. W.

1984-01-01

Data derived from a large network of electric field mills are used to determine the average diurnal variation of lightning in a Florida seacoast environment. The variation at the NASA Kennedy Space Center and the Cape Canaveral Air Force Station area is compared with standard weather observations of thunder, and the variation of all discharges in this area is compared with the statistics of cloud-to-ground flashes over most of the South Florida peninsula and offshore waters. The results show average diurnal variations that are consistent with statistics of thunder start times and the times of maximum thunder frequency, but that the actual lightning tends to stop one to two hours before the recorded thunder. The variation is also consistent with previous determinations of the times of maximum rainfall and maximum rainfall rate.

Climate change, phenology, and butterfly host plant utilization.

PubMed

Navarro-Cano, Jose A; Karlsson, Bengt; Posledovich, Diana; Toftegaard, Tenna; Wiklund, Christer; Ehrlén, Johan; Gotthard, Karl

2015-01-01

Knowledge of how species interactions are influenced by climate warming is paramount to understand current biodiversity changes. We review phenological changes of Swedish butterflies during the latest decades and explore potential climate effects on butterfly-host plant interactions using the Orange tip butterfly Anthocharis cardamines and its host plants as a model system. This butterfly has advanced its appearance dates substantially, and its mean flight date shows a positive correlation with latitude. We show that there is a large latitudinal variation in host use and that butterfly populations select plant individuals based on their flowering phenology. We conclude that A. cardamines is a phenological specialist but a host species generalist. This implies that thermal plasticity for spring development influences host utilization of the butterfly through effects on the phenological matching with its host plants. However, the host utilization strategy of A. cardamines appears to render it resilient to relatively large variation in climate.

Inter-Diffusion in the Presence of Free Convection

NASA Technical Reports Server (NTRS)

Gupta, Prabhat K.

1999-01-01

Because of their technological importance, establishment of the precise values of interdiffusion coefficients is important in multicomponent fluid systems. Such values are not available because diffusion is influenced by free convection due to compositionally induced density variations. In this project, earth based diffusion experiments are being performed in a viscous fluid system PbO-SiO2 at temperatures between 500-1000 C. This system is chosen because it shows a large variation in density with small changes in composition and is expected to show a large free convection effect. Infinite diffusion couples at different temperatures and times are being studied with different orientations with respect to gravity. Composition fields will be measured using an Electron Microprobe Analyzer and will be compared with the results of a complementary modeling study to extract the values of the true diffusion coefficient from the measured diffusion profiles.

The variation of corrosion potential with time for coated metal surfaces

NASA Technical Reports Server (NTRS)

Danford, M. D.; Knockemus, W. W.

1986-01-01

The variation of corrosion potential (EsubCORR) with time has been measured for 4130 steel coated with a preservative compound and for primer coated 2219-T87 aluminum. The data for coated steel samples show a great deal of scatter, and a smoothing procedure has been developed to enable proper interpretation of the data. The EsubCORR-time curves for coated steel exhibit a maximum, in agreement with the results of previous studies, where the data were the average of those for a large number of samples, while the present data were obtained from a single sample. In contrast, the EsubCORR-time curves for primer coated 2219-T87 aluminum samples show no significant variations, although considerable activity is indicated by the resistance-time and corrosion rate-time curves.

Parametric study of variation in cargo-airplane performance related to progression from current to spanloader designs

NASA Technical Reports Server (NTRS)

Toll, T. A.

1980-01-01

A parametric analysis was made to investigate the relationship between current cargo airplanes and possible future designs that may differ greatly in both size and configuration. The method makes use of empirical scaling laws developed from statistical studies of data from current and advanced airplanes and, in addition, accounts for payload density, effects of span distributed load, and variations in tail area ratio. The method is believed to be particularly useful for exploratory studies of design and technology options for large airplanes. The analysis predicts somewhat more favorable variations of the ratios of payload to gross weight and block fuel to payload as the airplane size is increased than has been generally understood from interpretations of the cube-square law. In terms of these same ratios, large all wing (spanloader) designs show an advantage over wing-fuselage designs.

Can the envisaged reductions of fossil fuel CO2 emissions be detected by atmospheric observations?

PubMed

Levin, Ingeborg; Rödenbeck, Christian

2008-03-01

The lower troposphere is an excellent receptacle, which integrates anthropogenic greenhouse gases emissions over large areas. Therefore, atmospheric concentration observations over populated regions would provide the ultimate proof if sustained emissions changes have occurred. The most important anthropogenic greenhouse gas, carbon dioxide (CO(2)), also shows large natural concentration variations, which need to be disentangled from anthropogenic signals to assess changes in associated emissions. This is in principle possible for the fossil fuel CO(2) component (FFCO(2)) by high-precision radiocarbon ((14)C) analyses because FFCO(2) is free of radiocarbon. Long-term observations of (14)CO(2) conducted at two sites in south-western Germany do not yet reveal any significant trends in the regional fossil fuel CO(2) component. We rather observe strong inter-annual variations, which are largely imprinted by changes of atmospheric transport as supported by dedicated transport model simulations of fossil fuel CO(2). In this paper, we show that, depending on the remoteness of the site, changes of about 7-26% in fossil fuel emissions in respective catchment areas could be detected with confidence by high-precision atmospheric (14)CO(2) measurements when comparing 5-year averages if these inter-annual variations were taken into account. This perspective constitutes the urgently needed tool for validation of fossil fuel CO(2) emissions changes in the framework of the Kyoto protocol and successive climate initiatives.

Heritability of metabolic syndrome traits in a large population-based sample[S

PubMed Central

van Dongen, Jenny; Willemsen, Gonneke; Chen, Wei-Min; de Geus, Eco J. C.; Boomsma, Dorret I.

2013-01-01

Heritability estimates of metabolic syndrome traits vary widely across studies. Some studies have suggested that the contribution of genes may vary with age or sex. We estimated the heritability of 11 metabolic syndrome-related traits and height as a function of age and sex in a large population-based sample of twin families (N = 2,792–27,021, for different traits). A moderate-to-high heritability was found for all traits [from H2 = 0.47 (insulin) to H2 = 0.78 (BMI)]. The broad-sense heritability (H2) showed little variation between age groups in women; it differed somewhat more in men (e.g., for glucose, H2 = 0.61 in young females, H2 = 0.56 in older females, H2 = 0.64 in young males, and H2= 0.27 in older males). While nonadditive genetic effects explained little variation in the younger subjects, nonadditive genetic effects became more important at a greater age. Our findings show that in an unselected sample (age range, ∼18–98 years), the genetic contribution to individual differences in metabolic syndrome traits is moderate to large in both sexes and across age. Although the prevalence of the metabolic syndrome has greatly increased in the past decades due to lifestyle changes, our study indicates that most of the variation in metabolic syndrome traits between individuals is due to genetic differences. PMID:23918046

Measurement of the human allele frequency spectrum demonstrates greater genetic drift in East Asians than in Europeans.

PubMed

Keinan, Alon; Mullikin, James C; Patterson, Nick; Reich, David

2007-10-01

Large data sets on human genetic variation have been collected recently, but their usefulness for learning about history and natural selection has been limited by biases in the ways polymorphisms were chosen. We report large subsets of SNPs from the International HapMap Project that allow us to overcome these biases and to provide accurate measurement of a quantity of crucial importance for understanding genetic variation: the allele frequency spectrum. Our analysis shows that East Asian and northern European ancestors shared the same population bottleneck expanding out of Africa but that both also experienced more recent genetic drift, which was greater in East Asians.

Pixel structures to compensate nonuniform threshold voltage and mobility of polycrystalline silicon thin-film transistors using subthreshold current for large-size active matrix organic light-emitting diode displays

NASA Astrophysics Data System (ADS)

Na, Jun-Seok; Kwon, Oh-Kyong

2014-01-01

We propose pixel structures for large-size and high-resolution active matrix organic light-emitting diode (AMOLED) displays using a polycrystalline silicon (poly-Si) thin-film transistor (TFT) backplane. The proposed pixel structures compensate the variations of the threshold voltage and mobility of the driving TFT using the subthreshold current. The simulated results show that the emission current error of the proposed pixel structure B ranges from -2.25 to 2.02 least significant bit (LSB) when the variations of the threshold voltage and mobility of the driving TFT are ±0.5 V and ±10%, respectively.

Temperatures of the martian surface and atmosphere: viking observation of diurnal and geometric variations.

PubMed

Kieffer, H H; Christensen, P R; Martin, T Z; Miner, E D; Palluconi, F D

1976-12-11

Selected observations made with the Viking infrared thermal mapper after the first landing are reported. Atmospheric temperatures measured at the latitude of the Viking 2 landing site (48 degrees N) over most of a martian day reveal a diurnal variation of at least 15 K, with peak temperatures occurring near 2.2 hours after noon, implying significant absorption of sunlight in the lower 30 km of the atmosphere by entrained dust. The summit temperature of Arsia Mons varies by a factor of nearly two each day; large diurnal temperature variation is characteristic of the south Tharsis upland and implies the presence of low thermal inertia material. The thermal inertia of material on the floors of several typical large craters is found to be higher than for the surrounding terrain; this suggests that craters are somehow effective in sorting aeolian material. Brightness temperatures of the Viking 1 landing area decrease at large emission angles; the intensity of reflected sunlight shows a more complex dependence on geometry than expected, implying atmospheric as well as surface scattering.

CAPITAL FLOWS, CONSUMPTION BOOMS AND ASSET BUBBLES: A BEHAVIOURAL ALTERNATIVE TO THE SAVINGS GLUT HYPOTHESIS

PubMed Central

Laibson, David; Mollerstrom, Johanna

2012-01-01

Bernanke (2005) hypothesized that a “global savings glut” was causing large trade imbalances. However, we show that the global savings rates did not show a robust upward trend during the relevant period. Moreover, if there had been a global savings glut there should have been a large investment boom in the countries that imported capital. Instead, those countries experienced consumption booms. National asset bubbles explain the international imbalances. The bubbles raised consumption, resulting in large trade deficits. In a sample of 18 OECD countries plus China, movements in home prices alone explain half of the variation in trade deficits. PMID:23750045

Temporal variations of radon concentration in the saturated soil of Alpine grassland: the role of groundwater flow.

PubMed

Perrier, Frédéric; Richon, Patrick; Sabroux, Jean-Christophe

2009-03-15

Radon concentration has been monitored from 1995 to 1999 in the soil of the Sur-Frêtes ridge (French Alps), covered with snow from November to April. Measurements were performed at 70 cm depth, with a sampling time of 1 h, at two points: the summit of the ridge, at an altitude of 1792 m, and the bottom of the ridge, at an altitude of 1590 m. On the summit, radon concentration shows a moderate seasonal variation, with a high value from October to April (winter), and a low value from May to September (summer). At the bottom of the ridge, a large and opposite seasonal variation is observed, with a low value in winter and a high value in summer. Fluctuations of the radon concentration seem to be associated with temperature variations, an effect which is largely delusory. Indeed, these variations are actually due to water infiltration. A simplified mixing model is used to show that, at the summit of the ridge, two effects compete in the radon response: a slow infiltration response, rich in radon, with a typical time scale of days, and a fast infiltration of radon-poor rainwater. At the bottom of the ridge, similarly, two groundwater contributions compete: one slow infiltration response, similar to the response seen at the summit, and an additional slower response, with a typical time scale of about a month. This second slower response can be interpreted as the aquifer discharge in response to snow melt. This study shows that, while caution is necessary to properly interpret the various effects, the temporal variations of the radon concentration in soil can be understood reasonably well, and appear to be a sensitive tool to study the subtle interplay of near surface transfer processes of groundwater with different transit times.

Origins of tropospheric ozone interannual variation (IAV) over Réunion: A model investigation.

PubMed

Liu, Junhua; Rodriguez, Jose M; Thompson, Anne M; Logan, Jennifer A; Douglass, Anne R; Olsen, Mark A; Steenrod, Stephen D; Posny, Francoise

2016-01-16

Observations from long-term ozonesonde measurements show robust variations and trends in the evolution of ozone in the middle and upper troposphere over Réunion Island (21.1°S, 55.5°E) in June-August. Here we examine possible causes of the observed ozone variation at Réunion Island using hindcast simulations by the stratosphere-troposphere Global Modeling Initiative chemical transport model (GMI-CTM) for 1992-2014, driven by assimilated Modern-Era Retrospective Analysis for Research and Applications (MERRA) meteorological fields. Réunion Island is at the edge of the subtropical jet, a region of strong stratospheric-tropospheric exchange (STE). Our analysis implies that the large interannual variation (IAV) of upper tropospheric ozone over Réunion is driven by the large IAV of the stratospheric influence. The IAV of the large-scale, quasi-horizontal wind patterns also contributes to the IAV of ozone in the upper troposphere. Comparison to a simulation with constant emissions indicates that increasing emissions do not lead to the maximum trend in the middle and upper troposphere over Réunion during austral winter implied by the sonde data. The effects of increasing emission over southern Africa are limited to the lower troposphere near the surface in August - September.

Origins of tropospheric ozone interannual variation (IAV) over Réunion: A model investigation

PubMed Central

Liu, Junhua; Rodriguez, Jose M.; Thompson, Anne M.; Logan, Jennifer A.; Douglass, Anne R.; Olsen, Mark A.; Steenrod, Stephen D.; Posny, Francoise

2018-01-01

Observations from long-term ozonesonde measurements show robust variations and trends in the evolution of ozone in the middle and upper troposphere over Réunion Island (21.1°S, 55.5°E) in June-August. Here we examine possible causes of the observed ozone variation at Réunion Island using hindcast simulations by the stratosphere-troposphere Global Modeling Initiative chemical transport model (GMI-CTM) for 1992–2014, driven by assimilated Modern-Era Retrospective Analysis for Research and Applications (MERRA) meteorological fields. Réunion Island is at the edge of the subtropical jet, a region of strong stratospheric-tropospheric exchange (STE). Our analysis implies that the large interannual variation (IAV) of upper tropospheric ozone over Réunion is driven by the large IAV of the stratospheric influence. The IAV of the large-scale, quasi-horizontal wind patterns also contributes to the IAV of ozone in the upper troposphere. Comparison to a simulation with constant emissions indicates that increasing emissions do not lead to the maximum trend in the middle and upper troposphere over Réunion during austral winter implied by the sonde data. The effects of increasing emission over southern Africa are limited to the lower troposphere near the surface in August – September. PMID:29657911

Temporal variations in natural attenuation of chlorinated aliphatic hydrocarbons in eutrophic river sediments impacted by a contaminated groundwater plume.

PubMed

Hamonts, Kelly; Kuhn, Thomas; Vos, Johan; Maesen, Miranda; Kalka, Harald; Smidt, Hauke; Springael, Dirk; Meckenstock, Rainer U; Dejonghe, Winnie

2012-04-15

Chlorinated aliphatic hydrocarbons (CAHs) often discharge into rivers as contaminated groundwater baseflow. Biotransformation, sorption and dilution of CAHs in the impacted river sediments have been reported to reduce discharge, but the effect of temporal variations in environmental conditions on the occurrence and extent of those processes in river sediments is largely unknown. We monitored the reduction of CAH discharge into the Zenne River during a 21-month period. Despite a relatively stable influx of CAHs from the groundwater, the total reduction in CAH discharge from 120 to 20 cm depth in the river sediments, on average 74 ± 21%, showed moderate to large temporal variations, depending on the riverbed location. High organic carbon and anaerobic conditions in the river sediments allowed microbial reductive dechlorination of both chlorinated ethenes and chlorinated ethanes. δ(13)C values of the CAHs showed that this biotransformation was remarkably stable over time, despite fluctuating pore water temperatures. Daughter products of the CAHs, however, were not detected in stoichiometric amounts and suggested the co-occurrence of a physical process reducing the concentrations of CAHs in the riverbed. This process was the main process causing temporal variations in natural attenuation of the CAHs and was most likely dilution by surface water-mixing. However, higher spatial resolution monitoring of flow transients in the riverbed is required to prove dilution contributions due to dynamic surface water-groundwater flow exchanges. δ(13)C values and a site-specific isotope enrichment factor for reductive dechlorination of the main groundwater pollutant vinyl chloride (VC) allowed assessment of changes over time in the extent of both biotransformation and dilution of VC for different scenarios in which those processes either occurred consecutively or simultaneously between 120 and 20 cm depth in the riverbed. The extent of reductive dechlorination of VC ranged from 27 to 89% and differed spatially but was remarkably stable over time, whereas the extent of VC reduction by dilution ranged from 6 to 94%, showed large temporal variations, and was often the main process contributing to the reduction of VC discharge into the river. Copyright © 2012 Elsevier Ltd. All rights reserved.

Lujiatun Psittacosaurids: Understanding Individual and Taphonomic Variation Using 3D Geometric Morphometrics

PubMed Central

Hedrick, Brandon P.; Dodson, Peter

2013-01-01

Psittacosaurus is one of the most abundant and speciose genera in the Dinosauria, with fifteen named species. The genus is geographically and temporally widespread with large sample sizes of several of the nominal species allowing detailed analysis of intra- and interspecific variation. We present a reanalysis of three separate, coeval species within the Psittacosauridae; P. lujiatunensis, P. major, and Hongshanosaurus houi from the Lujiatun beds of the Yixian Formation, northeastern China, using three-dimensional geometric morphometrics on a sample set of thirty skulls in combination with a reevaluation of the proposed character states for each species. Using these complementary methods, we show that individual and taphonomic variation are the joint causes of a large range of variation among the skulls when they are plotted in a morphospace. Our results demonstrate that there is only one species of Psittacosaurus within the Lujiatun beds and that the three nominal species represent different taphomorphotypes of P. lujiatunensis. The wide range of geometric morphometric variation in a single species of Psittacosaurus implies that the range of variation found in other dinosaurian groups may also be related to taphonomic distortion rather than interspecific variation. As the morphospace is driven primarily by variation resulting from taphonomic distortion, this study demonstrates that the geometric morphometric approach can only be used with great caution to delineate interspecific variation in Psittacosaurus and likely other dinosaur groups without a complementary evaluation of character states. This study presents the first application of 3D geometric morphometrics to the dinosaurian morphospace and the first attempt to quantify taphonomic variation in dinosaur skulls. PMID:23950887

Epigenetic variation, inheritance, and parent-of-origin effects of cytosine methylation in maize (Zea mays).

PubMed

Lauria, Massimiliano; Piccinini, Sara; Pirona, Raul; Lund, Gertrud; Viotti, Angelo; Motto, Mario

2014-03-01

Pure epigenetic variation, or epigenetic variation that is independent of genetic context, may provide a mechanism for phenotypic variation in the absence of DNA mutations. To estimate the extent of pure epigenetic variation within and across generations and to identify the DNA regions targeted, a group of eight plants derived from a highly inbred line of maize (Zea mays) was analyzed by the methylation-sensitive amplified polymorphism (MSAP) technique. We found that cytosine methylation (mC) differences among individuals accounted for up to 7.4% of CCGG sites investigated by MSAP. Of the differentially methylated fragments (DMFs) identified in the S0 generation, ∼12% were meiotically inherited for at least six generations. We show that meiotically heritable mC variation was consistently generated for an average of 0.5% CCGG sites per generation and that it largely occurred somatically. We provide evidence that mC variation can be established and inherited in a parent-of-origin manner, given that the paternal lineage is more prone to both forward and reverse mC changes. The molecular characterization of selected DMFs revealed that the variation was largely determined by CG methylation changes that map within gene regions. The expression analysis of genes overlapping with DMFs did not reveal an obvious correlation between mC variation and transcription, reinforcing the idea that the primary function of gene-body methylation is not to control gene expression. Because this study focuses on epigenetic variation in field-grown plants, the data presented herein pertain to spontaneous epigenetic changes of the maize genome in a natural context.

Epigenetic Variation, Inheritance, and Parent-of-Origin Effects of Cytosine Methylation in Maize (Zea mays)

PubMed Central

Lauria, Massimiliano; Piccinini, Sara; Pirona, Raul; Lund, Gertrud; Viotti, Angelo; Motto, Mario

2014-01-01

Pure epigenetic variation, or epigenetic variation that is independent of genetic context, may provide a mechanism for phenotypic variation in the absence of DNA mutations. To estimate the extent of pure epigenetic variation within and across generations and to identify the DNA regions targeted, a group of eight plants derived from a highly inbred line of maize (Zea mays) was analyzed by the methylation-sensitive amplified polymorphism (MSAP) technique. We found that cytosine methylation (mC) differences among individuals accounted for up to 7.4% of CCGG sites investigated by MSAP. Of the differentially methylated fragments (DMFs) identified in the S0 generation, ∼12% were meiotically inherited for at least six generations. We show that meiotically heritable mC variation was consistently generated for an average of 0.5% CCGG sites per generation and that it largely occurred somatically. We provide evidence that mC variation can be established and inherited in a parent-of-origin manner, given that the paternal lineage is more prone to both forward and reverse mC changes. The molecular characterization of selected DMFs revealed that the variation was largely determined by CG methylation changes that map within gene regions. The expression analysis of genes overlapping with DMFs did not reveal an obvious correlation between mC variation and transcription, reinforcing the idea that the primary function of gene-body methylation is not to control gene expression. Because this study focuses on epigenetic variation in field-grown plants, the data presented herein pertain to spontaneous epigenetic changes of the maize genome in a natural context. PMID:24374354

Interannual variability of Indian Ocean subtropical mode water subduction rate

NASA Astrophysics Data System (ADS)

Ma, Jie; Lan, Jian

2017-06-01

The interannual variation of Indian Ocean subtropical mode water (IOSTMW) subduction rate in the Southwest Indian Ocean from 1980 to 2007 is investigated in this paper based on Simple Ocean Data Assimilation (SODA) outputs. Climatology of subduction rate exceeds 75 m/year in the IOSTMW formation area. The renewal time of permanent pycnocline water mass based on the subduction rate is calculated for each density class: 3-6 years for IOSTMW (25.8 < σ θ < 26.2 kg m-3). Subduction rate in the Southwest Indian Ocean subtropical gyre exhibits a great year-to-year variability. This interannual variations of the IOSTMW subduction rate is primarily dominated by the lateral induction term, associated with the interannual variations of strong meridional gradient of winter mixed layer depth (MLD). The slope of the mixed layer depth in the mode water is closely linked to the large variations of deep late winter MLD in the mid-latitudes and negligible variations of shallow winter MLD in lower latitudes. It is further identified that the interannual variation of late winter MLD in this area is largely controlled by the latent and sensible heat flux components. The water volume of the permanent pycnocline in the IOSTMW distribution area is also found to show a significant interannual variability, and it is well correlated with the interannual variation of subduction rate.

The imprint of surface fluxes and transport on variations in total column carbon dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keppel-Aleks, G; Wennberg, PO; Washenfelder, RA

2012-01-01

New observations of the vertically integrated CO{sub 2} mixing ratio, , from ground-based remote sensing show that variations in are primarily determined by large-scale flux patterns. They therefore provide fundamentally different information than observations made within the boundary layer, which reflect the combined influence of large-scale and local fluxes. Observations of both and CO{sub 2} concentrations in the free troposphere show that large-scale spatial gradients induce synoptic-scale temporal variations in in the Northern Hemisphere midlatitudes through horizontal advection. Rather than obscure the signature of surface fluxes on atmospheric CO{sub 2}, these synoptic-scale variationsmore » provide useful information that can be used to reveal the meridional flux distribution. We estimate the meridional gradient in from covariations in and potential temperature, {theta}, a dynamical tracer, on synoptic timescales to evaluate surface flux estimates commonly used in carbon cycle models. We find that simulations using Carnegie Ames Stanford Approach (CASA) biospheric fluxes underestimate both the seasonal cycle amplitude throughout the Northern Hemisphere midlatitudes and the meridional gradient during the growing season. Simulations using CASA net ecosystem exchange (NEE) with increased and phase-shifted boreal fluxes better fit the observations. Our simulations suggest that climatological mean CASA fluxes underestimate boreal growing season NEE (between 45-65{sup o} N) by {approx}40%. We describe the implications for this large seasonal exchange on inference of the net Northern Hemisphere terrestrial carbon sink.« less

Investigations of a Cretaceous limestone with spectral induced polarization and scanning electron microscopy

NASA Astrophysics Data System (ADS)

Johansson, Sara; Sparrenbom, Charlotte; Fiandaca, Gianluca; Lindskog, Anders; Olsson, Per-Ivar; Dahlin, Torleif; Rosqvist, Håkan

2017-02-01

Characterization of varying bedrock properties is a common need in various contexts, ranging from large infrastructure pre-investigations to environmental protection. A direct current resistivity and time domain induced polarization (IP) survey aiming to characterize properties of a Cretaceous limestone was carried out in the Kristianstad basin, Sweden. The time domain IP data was processed with a recently developed method in order to suppress noise from the challenging urban setting in the survey area. The processing also enabled extraction of early decay times resulting in broader spectra of the time decays and inversion for Cole-Cole parameters. The aims of this study is to investigate if large-scale geoelectrical variations as well as small-scale structural and compositional variations exist within the Kristianstad limestone, and to evaluate the usefulness of Cole-Cole inverted IP data in early time ranges for bedrock characterization. The inverted sections showed variations within the limestone that could be caused by variations in texture and composition. Samples from a deep drilling in the Kristianstad basin were investigated with scanning electron microscopy and energy dispersive X-ray spectroscopy, and the results showed that varying amounts of pyrite, glauconite and clay matrix were present at different levels in the limestone. The local high IP anomalies in the limestone could be caused by these minerals otherwise the IP responses were generally weak. There were also differences in the texture of the limestone at different levels, governed by fossil shapes and composition, proportions of calcareous cement and matrix as well as amount of silicate grains. Textural variations may have implications on the variation in Cole-Cole relaxation time and frequency factor. However, more research is needed in order to directly connect microgeometrical properties in limestone to spectral IP responses. The results from this study show that it is possible to recover useable spectral information from early decay times. We also show that under certain conditions (e.g. relatively short relaxation times in the subsurface), it is possible to extract spectral information from time domain IP data measured with on-off times as short as 1 s.

Where does the plasmasphere begin? Revisit to topside ionospheric profiles in comparison with plasmaspheric TEC from Jason-1

NASA Astrophysics Data System (ADS)

Lee, Han-Byul; Kim, Yong Ha; Kim, Eunsol; Hong, Junseok; Kwak, Young-Sil

2016-10-01

Topside ionospheric profiles have been measured by Alouette 1 and ISIS 1/2 in the periods of 1962-1972 and 1972-1979, respectively. The profiles cover from the orbital altitude of 1000 km to the F2 peak and show large variations over local time, latitude, and seasons. We here analyze these variations in comparison with plasmaspheric total electron contents (pTECs) that were measured by Jason-1 satellite from the altitude of 1336 km to 20,200 km (GPS orbit). The scale heights of the profiles are generally smaller in the daytime than nighttime but show large day-to-day variations, implying that the ionospheric profiles at 1000 km are changing dynamically, rather than being in diffusive equilibrium. We also derived transition heights between O+ and H+, which show a clear minimum at dawn for low-latitude profiles due to decreasing O+ density at night. To compare with pTEC, we compute topside ionospheric total electron content (tiTEC) by integrating over 800-1336 km using the slope of the profiles. The tiTEC varies in a clear diurnal pattern from 0.3 to 1 and 3 total electron content unit (TECU, 1 TECU = 1016 el m-2) for low and high solar activity, respectively, whereas Jason-1 pTEC values are distributed over 2-6 TECU and 4-8 TECU for low and high solar activity, respectively, with no apparent diurnal modulation. Latitudinal variations of tiTEC show distinctive hemispheric asymmetry while that of Jason-1 pTEC is closely symmetric about the magnetic equator. The local time and latitudinal variations of tiTEC basically resemble those of the ionosphere but are characteristically different from those of Jason-1 pTEC. Based on the difference between tiTEC and pTEC variations, we propose that the region above 1300 km should be considered as the plasmasphere. Lower altitudes for the base of "plasmaspheric TEC," as used in some studies, would cause contamination of ionospheric influence.

Efficient genotype compression and analysis of large genetic variation datasets

PubMed Central

Layer, Ryan M.; Kindlon, Neil; Karczewski, Konrad J.; Quinlan, Aaron R.

2015-01-01

Genotype Query Tools (GQT) is a new indexing strategy that expedites analyses of genome variation datasets in VCF format based on sample genotypes, phenotypes and relationships. GQT’s compressed genotype index minimizes decompression for analysis, and performance relative to existing methods improves with cohort size. We show substantial (up to 443 fold) performance gains over existing methods and demonstrate GQT’s utility for exploring massive datasets involving thousands to millions of genomes. PMID:26550772

Genetic variation assessed with microsatellites in mass selection lines of the Pacific oyster ( Crassostrea gigas) in China

NASA Astrophysics Data System (ADS)

Wang, Xubo; Li, Qi; Yu, Hong; Kong, Lingfeng

2016-12-01

Four successive mass selection lines of the Pacific oyster, Crassostrea gigas, selected for faster growth in breeding programs in China were examined at ten polymorphic microsatellite loci to assess the level of allelic diversity and estimate the effective population size. These data were compared with those of their base population. The results showed that the genetic variation of the four generations were maintained at high levels with an average allelic richness of 18.8-20.6, and a mean expected heterozygosity of 0.902-0.921. They were not reduced compared with those of their base population. Estimated effective population sizes based on temporal variances in microsatellite frequencies were smaller to that of sex ratio-corrected broodstock count estimates. Using a relatively large number of broodstock and keeping an equal sex ratio in the broodstock each generation may have contributed to retaining the original genetic diversity and maintaining relatively large effective population size. The results obtained in this study showed that the genetic variation was not affected greatly by mass selection progress and high genetic variation still existed in the mass selection lines, suggesting that there is still potential for increasing the gains in future generations of C. gigas. The present study provided important information for future genetic improvement by selective breeding, and for the design of suitable management guidelines for genetic breeding of C. gigas.

Large-Scale Sidereal Anisotropy of Galactic Cosmic-Ray Intensity Observed by the Tibet Air Shower Array

NASA Astrophysics Data System (ADS)

Amenomori, M.; Ayabe, S.; Cui, S. W.; Danzengluobu; Ding, L. K.; Ding, X. H.; Feng, C. F.; Feng, Z. Y.; Gao, X. Y.; Geng, Q. X.; Guo, H. W.; He, H. H.; He, M.; Hibino, K.; Hotta, N.; Hu, Haibing; Hu, H. B.; Huang, J.; Huang, Q.; Jia, H. Y.; Kajino, F.; Kasahara, K.; Katayose, Y.; Kato, C.; Kawata, K.; Labaciren; Le, G. M.; Li, J. Y.; Lu, H.; Lu, S. L.; Meng, X. R.; Mizutani, K.; Mu, J.; Munakata, K.; Nagai, A.; Nanjo, H.; Nishizawa, M.; Ohnishi, M.; Ohta, I.; Onuma, H.; Ouchi, T.; Ozawa, S.; Ren, J. R.; Saito, T.; Sakata, M.; Sasaki, T.; Shibata, M.; Shiomi, A.; Shirai, T.; Sugimoto, H.; Takita, M.; Tan, Y. H.; Tateyama, N.; Torii, S.; Tsuchiya, H.; Udo, S.; Utsugi, T.; Wang, B. S.; Wang, H.; Wang, X.; Wang, Y. G.; Wu, H. R.; Xue, L.; Yamamoto, Y.; Yan, C. T.; Yang, X. C.; Yasue, S.; Ye, Z. H.; Yu, G. C.; Yuan, A. F.; Yuda, T.; Zhang, H. M.; Zhang, J. L.; Zhang, N. J.; Zhang, X. Y.; Zhang, Y.; Zhang, Yi; Zhaxisangzhu; Zhou, X. X.; Tibet Asγ Collaboration

2005-06-01

We present the large-scale sidereal anisotropy of Galactic cosmic-ray intensity in the multi-TeV region observed with the Tibet-III air shower array during the period from 1999 through 2003. The sidereal daily variation of cosmic rays observed in this experiment shows an excess of relative intensity around 4-7 hr local sidereal time as well as a deficit around 12 hr local sidereal time. While the amplitude of the excess is not significant when averaged over all declinations, the excess in individual declination bands becomes larger and clearer as the viewing direction moves toward the south. The maximum phase of the excess intensity changes from ~7 hr at the Northern Hemisphere to ~4 hr at the equatorial region. We also show that both the amplitude and the phase of the first harmonic vector of the daily variation are remarkably independent of primary energy in the multi-TeV region. This is the first result determining the energy and declination dependences of the full 24 hr profiles of the sidereal daily variation in the multi-TeV region with a single air shower experiment.

Measurements of temperature profiles at the exit of small rockets.

PubMed

Griggs, M; Harshbarger, F C

1966-02-01

The sodium line reversal technique was used to determine the reversal temperature profile across the exit of small rockets. Measurements were made on one 73-kg thrust rocket, and two 23-kg thrust rockets with different injectors. The large rocket showed little variation of reversal temperature across the plume. However, the 23-kg rockets both showed a large decrease of reversal temperature from the axis to the edge of the plume. In addition, the sodium line reversal technique of temperature measurement was compared with an infrared technique developed in these laboratories.

[Correlation of intraocular pressure variation after visual field examination with 24-hour intraocular pressure variations in primary open-angle glaucoma].

PubMed

Noro, Takahiko; Nakamoto, Kenji; Sato, Makoto; Yasuda, Noriko; Ito, Yoshinori; Ogawa, Shumpei; Nakano, Tadashi; Tsuneoka, Hiroshi

2014-10-01

We retrospectively examined intraocular pressure variations after visual field examination in primary open angle glaucoma (POAG), together with its influencing factors and its association with 24-hour intraocular pressure variations. Subjects were 94 eyes (52 POAG patients) subjected to measurements of 24-hour intraocular pressure and of changes in intraocular pressure after visual field examination using a Humphrey Visual Field Analyzer. Subjects were classified into three groups according to the magnitude of variation (large, intermediate and small), and 24-hour intraocular pressure variations were compared among the three groups. Factors influencing intraocular pressure variations after visual field examination and those associated with the large variation group were investigated. Average intraocular pressure variation after visual field examination was -0.28 ± 1.90 (range - 6.0(-) + 5.0) mmHg. No significant influencing factors were identified. The intraocular pressure at 3 a.m. was significantly higher in the large variation group than other two groups (p < 0.001). Central corneal thickness was correlated with the large variation group (odds ratio = 1.04; 95% confidence interval, 1.01-1.07 ; p = 0.02). No particular tendencies in intraocular pressure variations were found after visual field examination. Increases in intraocular pressure during the night might be associated with large intraocular pressure variations after visual field examination.

Aluminum tolerance in maize is associated with higher MATE1 gene copy number

PubMed Central

Maron, Lyza G.; Guimarães, Claudia T.; Kirst, Matias; Albert, Patrice S.; Birchler, James A.; Bradbury, Peter J.; Buckler, Edward S.; Coluccio, Alison E.; Danilova, Tatiana V.; Kudrna, David; Magalhaes, Jurandir V.; Piñeros, Miguel A.; Schatz, Michael C.; Wing, Rod A.; Kochian, Leon V.

2013-01-01

Genome structure variation, including copy number variation and presence/absence variation, comprises a large extent of maize genetic diversity; however, its effect on phenotypes remains largely unexplored. Here, we describe how copy number variation underlies a rare allele that contributes to maize aluminum (Al) tolerance. Al toxicity is the primary limitation for crop production on acid soils, which make up 50% of the world’s potentially arable lands. In a recombinant inbred line mapping population, copy number variation of the Al tolerance gene multidrug and toxic compound extrusion 1 (MATE1) is the basis for the quantitative trait locus of largest effect on phenotypic variation. This expansion in MATE1 copy number is associated with higher MATE1 expression, which in turn results in superior Al tolerance. The three MATE1 copies are identical and are part of a tandem triplication. Only three maize inbred lines carrying the three-copy allele were identified from maize and teosinte diversity panels, indicating that copy number variation for MATE1 is a rare, and quite likely recent, event. These maize lines with higher MATE1 copy number are also Al-tolerant, have high MATE1 expression, and originate from regions of highly acidic soils. Our findings show a role for copy number variation in the adaptation of maize to acidic soils in the tropics and suggest that genome structural changes may be a rapid evolutionary response to new environments. PMID:23479633

Estimation of physical activity levels using cell phone questionnaires: a comparison with accelerometry for evaluation of between-subject and within-subject variations.

PubMed

Bexelius, Christin; Sandin, Sven; Trolle Lagerros, Ylva; Litton, Jan-Eric; Löf, Marie

2011-09-25

Physical activity promotes health and longevity. Further elaboration of the role of physical activity for human health in epidemiological studies on large samples requires accurate methods that are easy to use, cheap, and possible to repeat. The use of telecommunication technologies such as cell phones is highly interesting in this respect. In an earlier report, we showed that physical activity level (PAL) assessed using a cell phone procedure agreed well with corresponding estimates obtained using the doubly labeled water method. However, our earlier study indicated high within-subject variation in relation to between-subject variations in PAL using cell phones, but we could not assess if this was a true variation of PAL or an artifact of the cell phone technique. Our objective was to compare within- and between-subject variations in PAL by means of cell phones with corresponding estimates using an accelerometer. In addition, we compared the agreement of daily PAL values obtained using the cell phone questionnaire with corresponding data obtained using an accelerometer. PAL was measured both with the cell phone questionnaire and with a triaxial accelerometer daily during a 2-week study period in 21 healthy Swedish women (20 to 45 years of age and BMI from 17.7 kg/m² to 33.6 kg/m²). The results were evaluated by fitting linear mixed effect models and descriptive statistics and graphs. With the accelerometer, 57% (95% confidence interval [CI] 40%-66%) of the variation was within subjects, while with the cell phone, within-subject variation was 76% (95% CI 59%-83%). The day-to-day variations in PAL observed using the cell phone questions agreed well with the corresponding accelerometer results. Both the cell phone questionnaire and the accelerometer showed high within-subject variations. Furthermore, day-to-day variations in PAL within subjects assessed using the cell phone agreed well with corresponding accelerometer values. Consequently, our cell phone questionnaire is a promising tool for assessing levels of physical activity. The tool may be useful for large-scale prospective studies.

Temporal and spatial variations of Gutenberg-Richter parameter and fractal dimension in Western Anatolia, Turkey

NASA Astrophysics Data System (ADS)

Bayrak, Erdem; Yılmaz, Şeyda; Bayrak, Yusuf

2017-05-01

The temporal and spatial variations of Gutenberg-Richter parameter (b-value) and fractal dimension (DC) during the period 1900-2010 in Western Anatolia was investigated. The study area is divided into 15 different source zones based on their tectonic and seismotectonic regimes. We calculated the temporal variation of b and DC values in each region using Zmap. The temporal variation of these parameters for the prediction of major earthquakes was calculated. The spatial distribution of these parameters is related to the stress levels of the faults. We observed that b and DC values change before the major earthquakes in the 15 seismic regions. To evaluate the spatial distribution of b and DC values, 0.50° × 0.50° grid interval were used. The b-values smaller than 0.70 are related to the Aegean Arc and Eskisehir Fault. The highest values are related to Sultandağı and Sandıklı Faults. Fractal correlation dimension varies from 1.65 to 2.60, which shows that the study area has a higher DC value. The lowest DC values are related to the joining area between Aegean and Cyprus arcs, Burdur-Fethiye fault zone. Some have concluded that b-values drop instantly before large shocks. Others suggested that temporally stable low b value zones identify future large earthquake locations. The results reveal that large earthquakes occur when b decreases and DC increases, suggesting that variation of b and DC can be used as an earthquake precursor. Mapping of b and DC values provide information about the state of stress in the region, i.e. lower b and higher DC values associated with epicentral areas of large earthquakes.

The uncertainties and causes of the recent changes in global evapotranspiration from 1982 to 2010

NASA Astrophysics Data System (ADS)

Dong, Bo; Dai, Aiguo

2017-07-01

Recent studies have shown considerable changes in terrestrial evapotranspiration (ET) since the early 1980s, but the causes of these changes remain unclear. In this study, the relative contributions of external climate forcing and internal climate variability to the recent ET changes are examined. Three datasets of global terrestrial ET and the CMIP5 multi-model ensemble mean ET are analyzed, respectively, to quantify the apparent and externally-forced ET changes, while the unforced ET variations are estimated as the apparent ET minus the forced component. Large discrepancies of the ET estimates, in terms of their trend, variability, and temperature- and precipitation-dependence, are found among the three datasets. Results show that the forced global-mean ET exhibits an upward trend of 0.08 mm day-1 century-1 from 1982 to 2010. The forced ET also contains considerable multi-year to decadal variations during the latter half of the 20th century that are caused by volcanic aerosols. The spatial patterns and interannual variations of the forced ET are more closely linked to precipitation than temperature. After removing the forced component, the global-mean ET shows a trend ranging from -0.07 to 0.06 mm day-1 century-1 during 1982-2010 with varying spatial patterns among the three datasets. Furthermore, linkages between the unforced ET and internal climate modes are examined. Variations in Pacific sea surface temperatures (SSTs) are found to be consistently correlated with ET over many land areas among the ET datasets. The results suggest that there are large uncertainties in our current estimates of global terrestrial ET for the recent decades, and the greenhouse gas (GHG) and aerosol external forcings account for a large part of the apparent trend in global-mean terrestrial ET since 1982, but Pacific SST and other internal climate variability dominate recent ET variations and changes over most regions.

Multifractal in Volatility of Family Business Stocks Listed on Casablanca STOCK Exchange

NASA Astrophysics Data System (ADS)

Lahmiri, Salim

In this paper, we check for existence of multifractal in volatility of Moroccan family business stock returns and in volatility of Casablanca market index returns based on multifractal detrended fluctuation analysis (MF-DFA) technique. Empirical results show strong evidence of multifractal characteristics in volatility series of both family business stocks and market index. In addition, it is found that small variations in volatility of family business stocks are persistent, whilst small variations in volatility of market index are anti-persistent. However, large variations in family business volatility and market index volatility are both anti-persistent. Furthermore, multifractal spectral analysis based results show strong evidence that volatility in Moroccan family business companies exhibits more multifractality than volatility in the main stock market. These results may provide insightful information for risk managers concerned with family business stocks.

Midlatitude D region variations measured from broadband radio atmospherics

NASA Astrophysics Data System (ADS)

Han, Feng

The high power, broadband very low frequency (VLF, 3--30 kHz) and extremely low frequency (ELF, 3--3000 Hz) electromagnetic waves generated by lightning discharges and propagating in the Earth-ionosphere waveguide can be used to measure the average electron density profile of the lower ionosphere (D region) across the wave propagation path due to several reflections by the upper boundary (lower ionosphere) of the waveguide. This capability makes it possible to frequently and even continuously monitor the D region electron density profile variations over geographically large regions, which are measurements that are essentially impossible by other means. These guided waves, usually called atmospherics (or sferics for short), are recorded by our sensors located near Duke University. The purpose of this work is to develop and implement algorithms to derive the variations of D region electron density profile which is modeled by two parameters (one is height and another is sharpness), by comparing the recorded sferic spectra to a series of model simulated sferic spectra from using a finite difference time domain (FDTD) code. In order to understand the time scales, magnitudes and sources for the midlatitude nighttime D region variations, we analyzed the sferic data of July and August 2005, and extracted both the height and sharpness of the D region electron density profile. The heights show large temporal variations of several kilometers on some nights and the relatively stable behavior on others. Statistical calculations indicate that the hourly average heights during the two months range between 82.0 km and 87.2 km with a mean value of 84.9 km and a standard deviation of 1.1 km. We also observed spatial variations of height as large as 2.0 km over 5 degrees latitudes on some nights, and no spatial variation on others. In addition, the measured height variations exhibited close correlations with local lightning occurrence rate on some nights but no correlation with local lightning or displaced lightning on others. The nighttime profile sharpness during 2.5 hours in two different nights was calculated, and the results were compared to the equivalent sharpness derived from International Reference Ionosphere (IRI) models. Both the absolute values and variation trends in IRI models are different from those in broadband measurements. Based on sferic data similar to those for nighttime, we also measured the day-time D region electron density profile variations in July and August 2005 near Duke University. As expected, the solar radiation is the dominant but not the only determinant source for the daytime D region profile height temporal variations. The observed quiet time heights showed close correlations with solar zenith angle changes but unexpected spatial variations not linked to the solar zenith angle were also observed on some days, with 15% of days exhibiting regional differences larger than 0.5 km. During the solar flare, the induced height change was approximately proportional to the logarithm of the X-ray fluxes. During the rising and decaying phases of the solar flare, the height changes correlated more consistently with the short (wavelength 0.5--4 A), rather than the long (wavelength 1--8 A) X-ray flux changes. The daytime profile sharpness during morning, noontime and afternoon periods in three different days and for the solar zenith angle range 20 to 75 degrees was calculated. These broadband measured results were compared to narrowband VLF measurements, IRI models and Faraday rotation base IRI models (called FIRI). The estimated sharpness from all these sources was more consistent when the solar zenith angle was small than when it was large. By applying the nighttime and daytime measurement techniques, we also derived the D region variations during sunrise and sunset periods. The measurements showed that both the electron density profile height and sharpness decrease during the sunrise period while increase during the sunset period.

Variation in nesting behavior of eight species of spider mites, Stigmaeopsis having sociality

NASA Astrophysics Data System (ADS)

Saito, Yutaka; Zhang, Yan-Xuan; Mori, Kotaro; Ito, Katsura; Sato, Yukie; Chittenden, Anthony R.; Lin, Jian-Zhen; Chae, Younghae; Sakagami, Takane; Sahara, Ken

2016-10-01

Nesting behavior is considered to be an important element of social living in animals. The spider mites belonging to the genus Stigmaeopsis spend their lives within nests produced from silk threads. Several of these species show cooperative sociality, while the others are subsocial. In order to identify the origins of this social behavior, comparisons of nest sizes, nesting behaviors (making nests continuously or separately), and their associated traits (fecal deposition patterns) were made for eight cogeneric Stigmaeopsis species showing various levels of social development. All of these species inhabit bamboo plants (Poaceae). We initially addressed the proximate factor of nest size variation. The variation in nest size of the eight species corresponded well with the variation in dorsal seta sc1 length, suggesting that nest size variation among species may have a genetic basis. The time spent within a nest (nest duration) increased with nest size on the respective host plants. Nest arrangement patterns varied among species showing different sized nests: Large nest builders continuously extended their nests, while middle and small nest-building species built new separate nests, which resulted in different social interaction times among species, and is thought to be closely related to social development. Fecal deposition behaviors also varied among Stigmaeopsis species, suggesting diversity in anti-predatory adaptations. Finally, we discuss how the variation in sociality observed within this genus is likely the result of nest size variation that initially evolved as anti-predator strategies.

Variation in nesting behavior of eight species of spider mites, Stigmaeopsis having sociality.

PubMed

Saito, Yutaka; Zhang, Yan-Xuan; Mori, Kotaro; Ito, Katsura; Sato, Yukie; Chittenden, Anthony R; Lin, Jian-Zhen; Chae, Younghae; Sakagami, Takane; Sahara, Ken

2016-10-01

Nesting behavior is considered to be an important element of social living in animals. The spider mites belonging to the genus Stigmaeopsis spend their lives within nests produced from silk threads. Several of these species show cooperative sociality, while the others are subsocial. In order to identify the origins of this social behavior, comparisons of nest sizes, nesting behaviors (making nests continuously or separately), and their associated traits (fecal deposition patterns) were made for eight cogeneric Stigmaeopsis species showing various levels of social development. All of these species inhabit bamboo plants (Poaceae). We initially addressed the proximate factor of nest size variation. The variation in nest size of the eight species corresponded well with the variation in dorsal seta sc1 length, suggesting that nest size variation among species may have a genetic basis. The time spent within a nest (nest duration) increased with nest size on the respective host plants. Nest arrangement patterns varied among species showing different sized nests: Large nest builders continuously extended their nests, while middle and small nest-building species built new separate nests, which resulted in different social interaction times among species, and is thought to be closely related to social development. Fecal deposition behaviors also varied among Stigmaeopsis species, suggesting diversity in anti-predatory adaptations. Finally, we discuss how the variation in sociality observed within this genus is likely the result of nest size variation that initially evolved as anti-predator strategies.

Hafnium isotope results from mid-ocean ridges and Kerguelen.

USGS Publications Warehouse

Patchett, P.J.

1983-01-01

176Hf/177Hf ratios are presented for oceanic volcanic rocks representing both extremes of the range of mantle Hf-Nd-Sr isotopic variation. Hf from critical mid-ocean ridge basalts shows that 176Hf/177Hf does indeed have a greater variability than 143Nd/144Nd and 87Sr/86Sr in the depleted mantle. This extra variation is essentially of a random nature, and can perhaps be understood in terms of known Rb/Sr-Sm/Nd-Lu/Hf fractionation relationships. At the other extreme of mantle isotopic compositions, 176Hf/177Hf ratios for igneous rocks from the Indian Ocean island of Kerguelen show a closely similar variation to published 143Nd/144Nd ratios for the same samples. Comparison of Hf-Nd-Sr isotopic relatonships for Tristan da Cunha, Kerguelen and Samoa reveals divergences in the mantle array for ocean-island magma sources, and perhaps suggests that these irregularities are largely the result of an extra component of 87Sr/86Sr variation.-G.R.

Hafnium isotope results from mid-ocean ridges and Kerguelen

USGS Publications Warehouse

Jonathan, Patchett P.

1983-01-01

176Hf/177Hf ratios are presented for oceanic volcanics representing both extremes of the range of mantle HfNdSr isotopic variation. Hf from critical mid-ocean ridgebasalts shows that 176Hf/177Hf does indeed have a greater variability than 143Nd/144Nd and 87Sr/86Sr in the depleted mantle. This extra variation is essentially of a random nature, and can perhaps be understood in terms of known Rb/SrSm/NdLu/Hf fractionation relationships. At the other extreme of mantle isotopic composition, 176Hf/177Hf ratios for igneous rocks from the Indian Ocean island of Kerguelen show a closely similar variation to published 143Nd/144Nd ratios for the same samples. Comparison of HfNdSr c relationships for Tristan da Cunha, Kerguelen and Samoa reveals divergences in the mantle array for ocean island magma sources, and perhaps suggests that these irregularities are largely the result of an extra component of 87Sr/86Sr variation. ?? 1983.

Patterns of variations in large pelagic fish: A comparative approach between the Indian and the Atlantic Oceans

NASA Astrophysics Data System (ADS)

Corbineau, A.; Rouyer, T.; Fromentin, J.-M.; Cazelles, B.; Fonteneau, A.; Ménard, F.

2010-07-01

Catch data of large pelagic fish such as tuna, swordfish and billfish are highly variable ranging from short to long term. Based on fisheries data, these time series are noisy and reflect mixed information on exploitation (targeting, strategy, fishing power), population dynamics (recruitment, growth, mortality, migration, etc.), and environmental forcing (local conditions or dominant climate patterns). In this work, we investigated patterns of variation of large pelagic fish (i.e. yellowfin tuna, bigeye tuna, swordfish and blue marlin) in Japanese longliners catch data from 1960 to 2004. We performed wavelet analyses on the yearly time series of each fish species in each biogeographic province of the tropical Indian and Atlantic Oceans. In addition, we carried out cross-wavelet analyses between these biological time series and a large-scale climatic index, i.e. the Southern Oscillation Index (SOI). Results showed that the biogeographic province was the most important factor structuring the patterns of variability of Japanese catch time series. Relationships between the SOI and the fish catches in the Indian and Atlantic Oceans also pointed out the role of climatic variability for structuring patterns of variation of catch time series. This work finally confirmed that Japanese longline CPUE data poorly reflect the underlying population dynamics of tunas.

The influence of the Atlantic Warm Pool on the Florida panhandle sea breeze

USGS Publications Warehouse

Misra, Vasubandhu; Moeller, Lauren; Stefanova, Lydia; Chan, Steven; O'Brien, James J.; Smith, Thomas J.; Plant, Nathaniel

2011-01-01

In this paper we examine the variations of the boreal summer season sea breeze circulation along the Florida panhandle coast from relatively high resolution (10 km) regional climate model integrations. The 23 year climatology (1979–2001) of the multidecadal dynamically downscaled simulations forced by the National Centers for Environmental Prediction–Department of Energy (NCEP-DOE) Reanalysis II at the lateral boundaries verify quite well with the observed climatology. The variations at diurnal and interannual time scales are also well simulated with respect to the observations. We show from composite analyses made from these downscaled simulations that sea breezes in northwestern Florida are associated with changes in the size of the Atlantic Warm Pool (AWP) on interannual time scales. In large AWP years when the North Atlantic Subtropical High becomes weaker and moves further eastward relative to the small AWP years, a large part of the southeast U.S. including Florida comes under the influence of relatively strong anomalous low-level northerly flow and large-scale subsidence consistent with the theory of the Sverdrup balance. This tends to suppress the diurnal convection over the Florida panhandle coast in large AWP years. This study is also an illustration of the benefit of dynamic downscaling in understanding the low-frequency variations of the sea breeze.

Auger electron intensity variations in oxygen-exposed large grain polycrystalline silver

NASA Technical Reports Server (NTRS)

Lee, W. S.; Outlaw, R. A.; Hoflund, G. B.; Davidson, M. R.

1989-01-01

Auger electron spectroscopic studies of the grains in oxygen-charged polycrystal-line silver show significant intensity variations as a function of crystallographic orientation. These intensity variations were observed by studies of the Auger images and line scans of the different grains (randomly selected) for each silver transition energy. The results can be attributed to the diffraction of the ejected Auger electrons and interpreted by corresponding changes in the electron mean-free path for inelastic scattering and by oxygen atom accumulation in the subsurface. The subsurface (second layer) octahedral sites increased in size because of surface relaxation and serve as a stable reservoir for the dissolved oxygen.

A sequential coalescent algorithm for chromosomal inversions

PubMed Central

Peischl, S; Koch, E; Guerrero, R F; Kirkpatrick, M

2013-01-01

Chromosomal inversions are common in natural populations and are believed to be involved in many important evolutionary phenomena, including speciation, the evolution of sex chromosomes and local adaptation. While recent advances in sequencing and genotyping methods are leading to rapidly increasing amounts of genome-wide sequence data that reveal interesting patterns of genetic variation within inverted regions, efficient simulation methods to study these patterns are largely missing. In this work, we extend the sequential Markovian coalescent, an approximation to the coalescent with recombination, to include the effects of polymorphic inversions on patterns of recombination. Results show that our algorithm is fast, memory-efficient and accurate, making it feasible to simulate large inversions in large populations for the first time. The SMC algorithm enables studies of patterns of genetic variation (for example, linkage disequilibria) and tests of hypotheses (using simulation-based approaches) that were previously intractable. PMID:23632894

The low noise limit in gene expression

DOE PAGES

Dar, Roy D.; Weinberger, Leor S.; Cox, Chris D.; ...

2015-10-21

Protein noise measurements are increasingly used to elucidate biophysical parameters. Unfortunately noise analyses are often at odds with directly measured parameters. Here we show that these inconsistencies arise from two problematic analytical choices: (i) the assumption that protein translation rate is invariant for different proteins of different abundances, which has inadvertently led to (ii) the assumption that a large constitutive extrinsic noise sets the low noise limit in gene expression. While growing evidence suggests that transcriptional bursting may set the low noise limit, variability in translational bursting has been largely ignored. We show that genome-wide systematic variation in translational efficiencymore » can-and in the case of E. coli does-control the low noise limit in gene expression. Therefore constitutive extrinsic noise is small and only plays a role in the absence of a systematic variation in translational efficiency. Lastly, these results show the existence of two distinct expression noise patterns: (1) a global noise floor uniformly imposed on all genes by expression bursting; and (2) high noise distributed to only a select group of genes.« less

Total Hydrogen Budget of the Equatorial Upper Stratosphere

DTIC Science & Technology

2010-02-24

series show quasi- biennial ( QBO ) variations which peak near 2.2 hPa in the equatorial upper stratosphere due to the large vertical gradients in CH4...Cordero et al., 1997] and directly relate to the observed QBO variations in H2O through CH4 oxidation. An increase in H2O mixing ratios during the early...by calculating the amplitudes of the QBO , annual, and semiannual cycles as function of pressure determined by a least squares regression fit to the

TIME DISTRIBUTIONS OF LARGE AND SMALL SUNSPOT GROUPS OVER FOUR SOLAR CYCLES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kilcik, A.; Yurchyshyn, V. B.; Abramenko, V.

2011-04-10

Here we analyze solar activity by focusing on time variations of the number of sunspot groups (SGs) as a function of their modified Zurich class. We analyzed data for solar cycles 20-23 by using Rome (cycles 20 and 21) and Learmonth Solar Observatory (cycles 22 and 23) SG numbers. All SGs recorded during these time intervals were separated into two groups. The first group includes small SGs (A, B, C, H, and J classes by Zurich classification), and the second group consists of large SGs (D, E, F, and G classes). We then calculated small and large SG numbers frommore » their daily mean numbers as observed on the solar disk during a given month. We report that the time variations of small and large SG numbers are asymmetric except for solar cycle 22. In general, large SG numbers appear to reach their maximum in the middle of the solar cycle (phases 0.45-0.5), while the international sunspot numbers and the small SG numbers generally peak much earlier (solar cycle phases 0.29-0.35). Moreover, the 10.7 cm solar radio flux, the facular area, and the maximum coronal mass ejection speed show better agreement with the large SG numbers than they do with the small SG numbers. Our results suggest that the large SG numbers are more likely to shed light on solar activity and its geophysical implications. Our findings may also influence our understanding of long-term variations of the total solar irradiance, which is thought to be an important factor in the Sun-Earth climate relationship.« less

Unified risk analysis of fatigue failure in ductile alloy components during all three stages of fatigue crack evolution process.

PubMed

Patankar, Ravindra

2003-10-01

Statistical fatigue life of a ductile alloy specimen is traditionally divided into three stages, namely, crack nucleation, small crack growth, and large crack growth. Crack nucleation and small crack growth show a wide variation and hence a big spread on cycles versus crack length graph. Relatively, large crack growth shows a lesser variation. Therefore, different models are fitted to the different stages of the fatigue evolution process, thus treating different stages as different phenomena. With these independent models, it is impossible to predict one phenomenon based on the information available about the other phenomenon. Experimentally, it is easier to carry out crack length measurements of large cracks compared to nucleating cracks and small cracks. Thus, it is easier to collect statistical data for large crack growth compared to the painstaking effort it would take to collect statistical data for crack nucleation and small crack growth. This article presents a fracture mechanics-based stochastic model of fatigue crack growth in ductile alloys that are commonly encountered in mechanical structures and machine components. The model has been validated by Ray (1998) for crack propagation by various statistical fatigue data. Based on the model, this article proposes a technique to predict statistical information of fatigue crack nucleation and small crack growth properties that uses the statistical properties of large crack growth under constant amplitude stress excitation. The statistical properties of large crack growth under constant amplitude stress excitation can be obtained via experiments.

Aerosol Daytime Variations over North and South America Derived from Multiyear AERONET Measurements

NASA Technical Reports Server (NTRS)

Zhang, Yan; Yu, Hongbin; Eck, Tom F.; Smirnov, Alexander; Chin, Mian; Remer, Lorraine A.; Bian, Huisheng; Tan, Qian; Levy, Roberrt; Holben, Brent N.

2012-01-01

This study analyzes the daytime variation of aerosol with seasonal distinction by using multi-year measurements from 54 of the Aerosol Robotic Network (AERONET) sites over North America, South America, and islands in surrounding oceans. The analysis shows a wide range of daily variability of aerosol optical depth (AOO) and Angstrom exponent depending on location and season. Possible reasons for daytime variations are given. The largest AOO daytime variation range at 440 nm, up to 75%, occurs in Mexico City, with maximum AOO in the afternoon. Large AOO daily variations are also observed in the polluted mid-Atlantic U.S. and U.S. West Coast with maximum AOO occurring in the afternoon in the mid-Atlantic U.S., but in the morning in the West Coast. In South American sites during the biomass burning season (August to October), maximum AOO generally occurs in the afternoon. But the daytime variation becomes smaller when sites are influenced more by long-range transported smoke than by local burning. Islands show minimum AOO in the morning and maximum AOO in the afternoon. The diverse patterns of aerosol daytime variation suggest that geostationary satellite measurements would be invaluable for characterizing aerosol temporal variations on regional and continental scales. In particular, simultaneous measurements of aerosols and aerosol precursors from a geostationary satellite would greatly aid in understanding the evolution of aerosol as determined by emissions, chemical transformations, and transport processes.

Solar Wind Speed Structure in the Inner Corona at 3-12 Ro

NASA Technical Reports Server (NTRS)

Woo, Richard

1995-01-01

Estimates of solar wind speed obtained by Armstrong et al. [1986] based on 1983 VLA multiple-station intensity scintillation measurements inside 12 R(sub o) have been correlated with the electron density structure observed in white-light coronagraph measurements. The observed large- scale and apparently systematic speed variations are found to depend primarily on changes in heliographic latitude and longitude, which leads to the first results on large-scale speed structure in the acceleration region of the solar wind. Over an equatorial hole, solar wind speed is relatively steady, with peak-to-peak variations of 50 km/s and an average of 230 km/s. In contrast, the near-Sun flow speed across the streamer belt shows regular large-scale variations in the range of 100-300 km/s. Based on four groups of data, the gradient is 36 km/s per degree in heliocentric coordinates (corresponding to a rise of 260 km/s over a spatial distance on the Sun of two arcmin) with a standard deviation of 2.4 km/s per degree. The lowest speeds most likely coincide with the stalks of coronal streamers observed in white-light measurements. The detection of significant wind shear over the streamer belt is consistent with in situ and scintillation measurements showing that the density spectrum has a power-law form characteristic of fully developed turbulence over a much broader range of scales than in neighboring regions.

Spatially resolved Spectroscopy of Europa’s Large-scale Compositional Units at 3-4 μm with Keck NIRSPEC

NASA Astrophysics Data System (ADS)

Fischer, P. D.; Brown, M. E.; Trumbo, S. K.; Hand, K. P.

2017-01-01

We present spatially resolved spectroscopic observations of Europa’s surface at 3-4 μm obtained with the near-infrared spectrograph and adaptive optics system on the Keck II telescope. These are the highest quality spatially resolved reflectance spectra of Europa’s surface at 3-4 μm. The observations spatially resolve Europa’s large-scale compositional units at a resolution of several hundred kilometers. The spectra show distinct features and geographic variations associated with known compositional units; in particular, large-scale leading hemisphere chaos shows a characteristic longward shift in peak reflectance near 3.7 μm compared to icy regions. These observations complement previous spectra of large-scale chaos, and can aid efforts to identify the endogenous non-ice species.

Study of new FNAL-NICADD extruded scintillator as active media of large EMCal of ALICE at LHC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oleg A. Grachov et al.

The current conceptual design of proposed Large EMCal of ALICE at LHC is based largely on the scintillating mega-tile/fiber technology implemented in CDF Endplug upgrade project and in both barrel and endcap electromagnetic calorimeters of the STAR. The cost of scintillating material leads us to the choice of extruded polystyrene based scintillator, which is available in new FNAL-NICADD facility. Result of optical measurements, such as light yield and light yield variation, show that it is possible to use this material as active media of Large EMCal of ALICE at LHC.

Linking lowermost mantle structure, core-mantle boundary heat flux and mantle plume formation

NASA Astrophysics Data System (ADS)

Li, Mingming; Zhong, Shijie; Olson, Peter

2018-04-01

The dynamics of Earth's lowermost mantle exert significant control on the formation of mantle plumes and the core-mantle boundary (CMB) heat flux. However, it is not clear if and how the variation of CMB heat flux and mantle plume activity are related. Here, we perform geodynamic model experiments that show how temporal variations in CMB heat flux and pulses of mantle plumes are related to morphologic changes of the thermochemical piles of large-scale compositional heterogeneities in Earth's lowermost mantle, represented by the large low shear velocity provinces (LLSVPs). We find good correlation between the morphologic changes of the thermochemical piles and the time variation of CMB heat flux. The morphology of the thermochemical piles is significantly altered during the initiation and ascent of strong mantle plumes, and the changes in pile morphology cause variations in the local and the total CMB heat flux. Our modeling results indicate that plume-induced episodic variations of CMB heat flux link geomagnetic superchrons to pulses of surface volcanism, although the relative timing of these two phenomena remains problematic. We also find that the density distribution in thermochemical piles is heterogeneous, and that the piles are denser on average than the surrounding mantle when both thermal and chemical effects are included.

Denudation rates and tectonic geomorphology of the Spanish Betic Cordillera

NASA Astrophysics Data System (ADS)

Bellin, N.; Vanacker, V.; Kubik, P. W.

2014-03-01

The tectonic control on landscape morphology and long-term denudation is largely documented for settings with high uplift rates. Relatively little is known about the rates of geomorphic response in areas of low tectonic uplift. Here, we evaluate spatial variations in denudation of the Spanish Betic Cordillera based on cosmogenic 10Be-derived denudation rates. Denudation rates are compared to published data on rock uplift and exhumation of the Betic Cordillera to evaluate steady-state topography. The spatial patterns of catchment-wide denudation rates (n=20) are then analysed together with topographic metrics of hillslope and channel morphology. Catchments draining the Betic ranges have relatively low denudation rates (64±54 mm kyr), but also show large variation as they range from 14 to 246 mm kyr-1. Catchment-wide denudation is linearly proportional to the mean hillslope gradient and local relief. Despite large spatial variation in denudation, the magnitude and spatial pattern of denudation rates are generally consistent with longer-term local uplift rates derived from elevated marine deposits, fission-track measurements and vertical fault slip rates. This might be indicative of a steady-state topography where rock uplift is balanced by denudation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geltman, S.

Recent measurements on CO{sub 2}-laser-assisted electron-atom collisions have shown large inconsistencies with the Kroll-Watson formula for small-angle scattering. We have carried out a detailed study to compare the predictions of Kroll-Watson theory (for both single and multimode fields) with those of conventional perturbation theory for stimulated free-free transitions. It is found that for {ital E}{sub 0}/2{omega}{sup 2}{lt}1, where perturbation theory is valid, there are large differences with the Kroll-Watson theory. Comparisons of experimental variations with respect to scattering angle and electron energy show much better agreement with perturbation theory than with Kroll-Watson theory. A study of the angular variations inmore » perturbation theory shows that use of the {open_quote}{open_quote}outgoing{close_quote}{close_quote} wave final state gives much better agreement with experiment than does the {open_quote}{open_quote}ingoing{close_quote}{close_quote} wave final state, which is different from the choice made in early bremsstrahlung theory. {copyright} {ital 1996 The American Physical Society.}« less

Mutation Rate Variation is a Primary Determinant of the Distribution of Allele Frequencies in Humans

PubMed Central

Pritchard, Jonathan K.

2016-01-01

The site frequency spectrum (SFS) has long been used to study demographic history and natural selection. Here, we extend this summary by examining the SFS conditional on the alleles found at the same site in other species. We refer to this extension as the “phylogenetically-conditioned SFS” or cSFS. Using recent large-sample data from the Exome Aggregation Consortium (ExAC), combined with primate genome sequences, we find that human variants that occurred independently in closely related primate lineages are at higher frequencies in humans than variants with parallel substitutions in more distant primates. We show that this effect is largely due to sites with elevated mutation rates causing significant departures from the widely-used infinite sites mutation model. Our analysis also suggests substantial variation in mutation rates even among mutations involving the same nucleotide changes. In summary, we show that variable mutation rates are key determinants of the SFS in humans. PMID:27977673

Runoff and sediment variation in the areas with high and coarse sediment yield of the middle Yellow River

NASA Astrophysics Data System (ADS)

Zhang, Pan; Yao, Wenyi; Xiao, Peiqing; Sun, Weiying

2018-02-01

Massive water and soil conservation works (WSCW) have been conducted in the areas with high and coarse sediment yield of the middle Yellow River since 1982. With the impending effects of climate change, it is necessary to reconsider the effects of WSCW on runoff and sediment variation at decadal and regional scales. Using long-term official and synthesized data, the WSCW impacts on reducing water and soil loss were studied in Sanchuanhe River watershed. Results showed that the sediment and runoff generated from this area showed a decreasing trend in the past 50 years. A great progress has been achieved in erosion control since the 1970s. After the 4 soil and water conservation harnessing stages during the period from 1970 to 2006, the sediment and runoff yield showed decreases with the extension of harnessing. The results revealed that human activities exerted the largest effects on the sediment reduction and explained 66.6% of the variation in the specific sediment yield. The contribution of rainfall variation to runoff reduction was as large as human activities. A great benefit have been obtained in water and soil loss control in this area.

Variational treatment of entanglement in the Dicke model

NASA Astrophysics Data System (ADS)

Bakemeier, L.; Alvermann, A.; Fehske, H.

2015-10-01

We introduce a variational ansatz for the Dicke model that extends mean-field theory through the inclusion of spin-oscillator correlations. The correlated variational state is obtained from the mean-field product state via a unitary transformation. The ansatz becomes correct in the limit of large oscillator frequency and in the limit of a large spin, for which it captures the leading quantum corrections to the classical limit exactly including the spin-oscillator entanglement entropy. We explain the origin of the unitary transformation before we show that the ansatz improves substantially upon mean-field theory, giving near exact results for the ground state energy and very good results for other observables. We then discuss why the ansatz still encounters problems in the transition regime at moderate spin lengths, where it fails to capture the precursors of the superradiant quantum phase transition faithfully. This observation illustrates the principal limits of semi-classical formulations, even after they are extended with correlations and entanglement.

Quality variations in black musli (curculigo orchioides gaertn.).

PubMed

Mathew, P P Joy Samuel; Savithri, K E; Skaria, Baby P; Kurien, Kochurani

2004-07-01

Black musli (Curculigo orchioides Gaertn.) one of the ayurvedic dasapushpa and a rejuvenating and aphrodisiac drug. Is on the verge of extinction and needs to be conserved and cultivated. Large variations are also observed in the quality of the crude drug available in the market. Study on the quality of C. orchioides in natural habitat, under cultivation and in trade in south India showed that there was considerable variation with biotypes and habitats. Drugs collected form the natural habitat was superior in quality to that produced by cultivation. Among the market samples collected from the various Zones of kerala, those from the High Ranges were superior in most of the quality parameters, which indicated its superiority for high quality drug formulation. Among the southern states, Tamil Nadu samples ranked next to High Range samples in this respect. There exists large variability in the market samples and there is felt-need for proper standardization of the crude drug for ensuring quality in the drug formulations.

De novo assembly of soybean wild relatives for pan-genome analysis of diversity and agronomic traits.

PubMed

Li, Ying-hui; Zhou, Guangyu; Ma, Jianxin; Jiang, Wenkai; Jin, Long-guo; Zhang, Zhouhao; Guo, Yong; Zhang, Jinbo; Sui, Yi; Zheng, Liangtao; Zhang, Shan-shan; Zuo, Qiyang; Shi, Xue-hui; Li, Yan-fei; Zhang, Wan-ke; Hu, Yiyao; Kong, Guanyi; Hong, Hui-long; Tan, Bing; Song, Jian; Liu, Zhang-xiong; Wang, Yaoshen; Ruan, Hang; Yeung, Carol K L; Liu, Jian; Wang, Hailong; Zhang, Li-juan; Guan, Rong-xia; Wang, Ke-jing; Li, Wen-bin; Chen, Shou-yi; Chang, Ru-zhen; Jiang, Zhi; Jackson, Scott A; Li, Ruiqiang; Qiu, Li-juan

2014-10-01

Wild relatives of crops are an important source of genetic diversity for agriculture, but their gene repertoire remains largely unexplored. We report the establishment and analysis of a pan-genome of Glycine soja, the wild relative of cultivated soybean Glycine max, by sequencing and de novo assembly of seven phylogenetically and geographically representative accessions. Intergenomic comparisons identified lineage-specific genes and genes with copy number variation or large-effect mutations, some of which show evidence of positive selection and may contribute to variation of agronomic traits such as biotic resistance, seed composition, flowering and maturity time, organ size and final biomass. Approximately 80% of the pan-genome was present in all seven accessions (core), whereas the rest was dispensable and exhibited greater variation than the core genome, perhaps reflecting a role in adaptation to diverse environments. This work will facilitate the harnessing of untapped genetic diversity from wild soybean for enhancement of elite cultivars.

Variability of tropical cyclone rapid intensification in the North Atlantic and its relationship with climate variations

NASA Astrophysics Data System (ADS)

Wang, Chunzai; Wang, Xidong; Weisberg, Robert H.; Black, Michael L.

2017-12-01

The paper uses observational data from 1950 to 2014 to investigate rapid intensification (RI) variability of tropical cyclones (TCs) in the North Atlantic and its relationships with large-scale climate variations. RI is defined as a TC intensity increase of at least 15.4 m/s (30 knots) in 24 h. The seasonal RI distribution follows the seasonal TC distribution, with the highest number in September. Although an RI event can occur anywhere over the tropical North Atlantic (TNA), there are three regions of maximum RI occurrence: (1) the western TNA of 12°N-18°N and 60°W-45°W, (2) the Gulf of Mexico and the western Caribbean Sea, and (3) the open ocean southeast and east of Florida. RI events also show a minimum value in the eastern Caribbean Sea north of South America—a place called a hurricane graveyard due to atmospheric divergence and subsidence. On longer time scales, RI displays both interannual and multidecadal variability, but RI does not show a long-term trend due to global warming. The top three climate indices showing high correlations with RI are the June-November ENSO and Atlantic warm pool indices, and the January-March North Atlantic oscillation index. It is found that variabilities of vertical wind shear and TC heat potential are important for TC RI in the hurricane main development region, whereas relative humidity at 500 hPa is the main factor responsible for TC RI in the eastern TNA. However, the large-scale oceanic and atmospheric variables analyzed in this study do not show an important role in TC RI in the Gulf of Mexico and the open ocean southeast and east of Florida. This suggests that other factors such as small-scale changes of oceanic and atmospheric variables or TC internal processes may be responsible for TC RI in these two regions. Additionally, the analyses indicate that large-scale atmospheric and oceanic variables are not critical to TC genesis and formation; however, once a tropical depression forms, large-scale climate variations play a role in TC intensification.

An Investigation of the Optical Microvariability of the Blazar PG 0735+178

NASA Astrophysics Data System (ADS)

McFarland, J. P.; Miller, H. R.; Carini, M. T.; Jang, M.; Noble, J. C.

2003-05-01

The blazar PG 0735+178 was monitored for more than 20 nights for microvariability on multiple timescales. We present this data which shows variations of amplitude several hundredths to several tenths of a magnitude on timescales of hours to days. The object also has exhibited variations with an amplitude as large as 2 magnitudes on the timescale of years. This microvariability will be investigated as a function of outburst and quiescent states of the object over the course of these timescales. These variations place severe limits on the size of the emitting region, and provide constraints for the physical processes responsible for these variations. JPM and HRM are grateful for support of a grant from the Research Corporation and the PEGA-RPE program at Georgia State University.

Large Calcium Isotopic Variation in Peridotitic Xenoliths from North China Craton

NASA Astrophysics Data System (ADS)

Huang, S.; Zhao, X.; Zhang, Z.

2016-12-01

Calcium is the fifth most abundant element in the Earth. The Ca isotopic composition of the Earth is important in many aspects, ranging from tracing the Ca cycle on the Earth to comparing the Earth to other terrestrial planets. There is large mass-dependent Ca isotopic variation, measured as δ44/40Ca relative to a standard sample, in terrestrial igneous rocks: about 2 per mil in silicate rocks, compared to 3 per mil in carbonates. Therefore, a good understanding of the Ca isotopic variation in igneous rocks is necessary. Here we report Ca isotopic data on a series of peridotitic xenoliths from North China Craton (NCC). There is about 1 per mil δ44/40Ca variation in these NCC peridotites: The highest δ44/40Ca is close to typical mantle values, and the lowest δ44/40Ca is found in an Fe-rich peridotite, -1.13 relative to normal mantle (or -0.08 on the SRM 915a scale). This represents the lowest δ44/40Ca value ever reported for igneous rocks. Combined with published Fe isotopic data on the same samples, our data show a positive linear correlation between δ44/40Ca and δ57/54Fe in NCC peridotites. This trend is inconsistent with mixing a low-δ44/40Ca and -δ57/54Fe sedimentary component with a normal mantle component. Rather, it is best explained as the result of kinetic isotopic effect caused by melt-peridotite reaction on a time scale of several hundreds of years. In detail, basaltic melt reacts with peridotite, replaces orthopyroxene with clinopyroxene, and increases the Fo number of olivine. Consistent with this interpretation, our on-going Mg isotopic study shows that low-δ44/40Ca and -δ57/54Fe NCC peridotites also have heavier Mg isotopes compared to normal mantle. Our study shows that mantle metasomatism plays an important role generating stable isotopic variations within the Earth's mantle.

Variations and asymmetries in regional brain surface in the genus Homo.

PubMed

Balzeau, Antoine; Holloway, Ralph L; Grimaud-Hervé, Dominique

2012-06-01

Paleoneurology is an important field of research within human evolution studies. Variations in size and shape of an endocast help to differentiate among fossil hominin species whereas endocranial asymmetries are related to behavior and cognitive function. Here we analyse variations of the surface of the frontal, parieto-temporal and occipital lobes among different species of Homo, including 39 fossil hominins, ten fossil anatomically modern Homo sapiens and 100 endocasts of extant modern humans. We also test for the possible asymmetries of these features in a large sample of modern humans and observe individual particularities in the fossil specimens. This study contributes important new information about the brain evolution in the genus Homo. Our results show that the general pattern of surface asymmetry for the different regional brain surfaces in fossil species of Homo does not seem to be different from the pattern described in a large sample of anatomically modern H. sapiens, i.e., the right hemisphere has a larger surface than the left, as do the right frontal, the right parieto-temporal and the left occipital lobes compared with the contra-lateral side. It also appears that Asian Homo erectus specimens are discriminated from all other samples of Homo, including African and Georgian specimens that are also sometimes included in that taxon. The Asian fossils show a significantly smaller relative size of the parietal and temporal lobes. Neandertals and anatomically modern H. sapiens, who share the largest endocranial volume of all hominins, show differences when considering the relative contribution of the frontal, parieto-temporal and occipital lobes. These results illustrate an original variation in the pattern of brain organization in hominins independent of variations in total size. The globularization of the brain and the enlargement of the parietal lobes could be considered derived features observed uniquely in anatomically modern H. sapiens. Copyright © 2012 Elsevier Ltd. All rights reserved.

Reducing variation in a rabbit vaccine safety study with particular emphasis on housing conditions and handling.

PubMed

Verwer, Cynthia M; van der Ark, Arno; van Amerongen, Geert; van den Bos, Ruud; Hendriksen, Coenraad F M

2009-04-01

This paper describes the results of a study of the effects of modified housing conditions, conditioning and habituation on humans using a rabbit model for monitoring whole-cell pertussis vaccine (pWCV)-induced adverse effects. The study has been performed with reference to previous vaccine safety studies of pWCV in rabbits in which results were difficult to interpret due to the large variation in experimental outcome, especially in the key parameter deep-body temperature (T(b)). Certain stressful laboratory conditions, as well as procedures involving humans, e.g. blood sampling, inoculation and cage-cleaning, were hypothesized to cause this large variation. The results of this study show that under modified housing conditions rabbits have normal circadian body temperatures. This allowed discrimination of pWCV-induced adverse effects in which handled rabbits tended to show a dose-related increase in temperature after inoculation with little variance, whereas non-handled rabbits did not. Effects of experimental and routine procedures on body temperature were significantly reduced under modified conditions and were within the normal T(b) range. Handled animals reacted less strongly and with less variance to experimental procedures, such as blood sampling, injection and cage-cleaning, than non-handled rabbits. Overall, handling had a positive effect on the behaviour of the animals. Data show that the housing modifications have provided a more robust model for monitoring pWCV adverse effects. Furthermore, conditioning and habituation of rabbits to humans reduce the variation in experimental outcome, which might allow for a reduction in the number of animals used. In addition, this also reduces distress and thus contributes to refining this animal model.

An investigation of the photometric variability of confirmed and candidate Galactic Be stars using ASAS-3 data

NASA Astrophysics Data System (ADS)

Bernhard, Klaus; Otero, Sebastián; Hümmerich, Stefan; Kaltcheva, Nadejda; Paunzen, Ernst; Bohlsen, Terry

2018-05-01

We present an investigation of a large sample of confirmed (N=233) and candidate (N=54) Galactic classical Be stars (mean V magnitude range of 6.4 to 12.6 mag), with the main aim of characterizing their photometric variability. Our sample stars were preselected among early-type variables using light curve morphology criteria. Spectroscopic information was gleaned from the literature, and archival and newly-acquired spectra. Photometric variability was analyzed using archival ASAS-3 time series data. To enable a comparison of results, we have largely adopted the methodology of Labadie-Bartz et al. (2017), who carried out a similar investigation based on KELT data. Complex photometric variations were established in most stars: outbursts on different time-scales (in 73±5 % of stars), long-term variations (36±6 %), periodic variations on intermediate time-scales (1±1 %) and short-term periodic variations (6±3 %). 24±6 % of the outbursting stars exhibit (semi)periodic outbursts. We close the apparent void of rare outbursters reported by Labadie-Bartz et al. (2017), and show that Be stars with infrequent outbursts are not rare. While we do not find a significant difference in the percentage of stars showing outbursts among early-type, mid-type and late-type Be stars, we show that early-type Be stars exhibit much more frequent outbursts. We have measured rising and falling times for well-covered and well-defined outbursts. Nearly all outburst events are characterized by falling times that exceed the rising times. No differences were found between early-, mid- and late-type stars; a single non-linear function adequately describes the ratio of falling time to rising time across all spectral subtypes, with the ratio being larger for short events.

The effect of structural changes on charge transfer states in a light-harvesting carotenoid-diaryl-porphyrin-C{sub 60} molecular triad

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olguin, Marco; Basurto, Luis; Zope, Rajendra R.

We present a detailed study of charge transfer (CT) excited states for a large number of configurations in a light-harvesting Carotenoid-diaryl-Porphyrin-C{sub 60} (CPC{sub 60}) molecular triad. The chain-like molecular triad undergoes photoinduced charge transfer process exhibiting a large excited state dipole moment, making it suitable for application to molecular-scale opto-electronic devices. An important consideration is that the structural flexibility of the CPC{sub 60} triad impacts its dynamics in solvents. Since experimentally measured dipole moments for the triad of ∼110 D and ∼160 D strongly indicate a range in structural variability in the excited state, studying the effect of structural changesmore » on the CT excited state energetics furthers the understanding of its charge transfer states. We have calculated the variation in the lowest CT excited state energies by performing a scan of possible variation in the structure of the triad. Some of these configurations were generated by incrementally scanning a 360° torsional (dihedral) twist at the C{sub 60}-porhyrin linkage and the porphyrin-carotenoid linkage. Additionally, five different CPC{sub 60} conformations were studied to determine the effect of pi-conjugation and particle-hole Coulombic attraction on the CT excitation energies. Our calculations show that configurational changes in the triad induces a variation of ∼0.6 eV in CT excited state energies in the gas-phase. The corresponding calculated excited state dipoles show a range of 47 D–188 D. The absorption spectra and density of states of these structures show little variation except for the structures where the porphyrin and aryl conjugation is changed.« less

Wavelet Analyses of Oil Prices, USD Variations and Impact on Logistics

NASA Astrophysics Data System (ADS)

Melek, M.; Tokgozlu, A.; Aslan, Z.

2009-07-01

This paper is related with temporal variations of historical oil prices and Dollar and Euro in Turkey. Daily data based on OECD and Central Bank of Turkey records beginning from 1946 has been considered. 1D-continuous wavelets and wavelet packets analysis techniques have been applied on data. Wavelet techniques help to detect abrupt changing's, increasing and decreasing trends of data. Estimation of variables has been presented by using linear regression estimation techniques. The results of this study have been compared with the small and large scale effects. Transportation costs of track show a similar variation with fuel prices. The second part of the paper is related with estimation of imports, exports, costs, total number of vehicles and annual variations by considering temporal variation of oil prices and Dollar currency in Turkey. Wavelet techniques offer a user friendly methodology to interpret some local effects on increasing trend of imports and exports data.

Implications of a primordial origin for the dispersion in D/H in quasar absorption systems

PubMed Central

Copi, Craig J.; Olive, Keith A.; Schramm, David N.

1998-01-01

We explore the difficulties with a primordial origin of variations of D/H in quasar absorption systems. In particular we examine options such as a very large-scale inhomogeneity in the baryon content of the universe. We show that very large-scale (much larger than 1 Mpc) isocurvature perturbations are excluded by current cosmic microwave background observations. Smaller-scale ad hoc perturbations (∼1 Mpc) still may lead to a large dispersion in primordial abundances but are subject to other constraints. PMID:9501162

Implications of a primordial origin for the dispersion in D/H in quasar absorption systems.

PubMed

Copi, C J; Olive, K A; Schramm, D N

1998-03-17

We explore the difficulties with a primordial origin of variations of D/H in quasar absorption systems. In particular we examine options such as a very large-scale inhomogeneity in the baryon content of the universe. We show that very large-scale (much larger than 1 Mpc) isocurvature perturbations are excluded by current cosmic microwave background observations. Smaller-scale ad hoc perturbations (approximately 1 Mpc) still may lead to a large dispersion in primordial abundances but are subject to other constraints.

Mapping human genetic diversity in Asia.

PubMed

Abdulla, Mahmood Ameen; Ahmed, Ikhlak; Assawamakin, Anunchai; Bhak, Jong; Brahmachari, Samir K; Calacal, Gayvelline C; Chaurasia, Amit; Chen, Chien-Hsiun; Chen, Jieming; Chen, Yuan-Tsong; Chu, Jiayou; Cutiongco-de la Paz, Eva Maria C; De Ungria, Maria Corazon A; Delfin, Frederick C; Edo, Juli; Fuchareon, Suthat; Ghang, Ho; Gojobori, Takashi; Han, Junsong; Ho, Sheng-Feng; Hoh, Boon Peng; Huang, Wei; Inoko, Hidetoshi; Jha, Pankaj; Jinam, Timothy A; Jin, Li; Jung, Jongsun; Kangwanpong, Daoroong; Kampuansai, Jatupol; Kennedy, Giulia C; Khurana, Preeti; Kim, Hyung-Lae; Kim, Kwangjoong; Kim, Sangsoo; Kim, Woo-Yeon; Kimm, Kuchan; Kimura, Ryosuke; Koike, Tomohiro; Kulawonganunchai, Supasak; Kumar, Vikrant; Lai, Poh San; Lee, Jong-Young; Lee, Sunghoon; Liu, Edison T; Majumder, Partha P; Mandapati, Kiran Kumar; Marzuki, Sangkot; Mitchell, Wayne; Mukerji, Mitali; Naritomi, Kenji; Ngamphiw, Chumpol; Niikawa, Norio; Nishida, Nao; Oh, Bermseok; Oh, Sangho; Ohashi, Jun; Oka, Akira; Ong, Rick; Padilla, Carmencita D; Palittapongarnpim, Prasit; Perdigon, Henry B; Phipps, Maude Elvira; Png, Eileen; Sakaki, Yoshiyuki; Salvador, Jazelyn M; Sandraling, Yuliana; Scaria, Vinod; Seielstad, Mark; Sidek, Mohd Ros; Sinha, Amit; Srikummool, Metawee; Sudoyo, Herawati; Sugano, Sumio; Suryadi, Helena; Suzuki, Yoshiyuki; Tabbada, Kristina A; Tan, Adrian; Tokunaga, Katsushi; Tongsima, Sissades; Villamor, Lilian P; Wang, Eric; Wang, Ying; Wang, Haifeng; Wu, Jer-Yuarn; Xiao, Huasheng; Xu, Shuhua; Yang, Jin Ok; Shugart, Yin Yao; Yoo, Hyang-Sook; Yuan, Wentao; Zhao, Guoping; Zilfalil, Bin Alwi

2009-12-11

Asia harbors substantial cultural and linguistic diversity, but the geographic structure of genetic variation across the continent remains enigmatic. Here we report a large-scale survey of autosomal variation from a broad geographic sample of Asian human populations. Our results show that genetic ancestry is strongly correlated with linguistic affiliations as well as geography. Most populations show relatedness within ethnic/linguistic groups, despite prevalent gene flow among populations. More than 90% of East Asian (EA) haplotypes could be found in either Southeast Asian (SEA) or Central-South Asian (CSA) populations and show clinal structure with haplotype diversity decreasing from south to north. Furthermore, 50% of EA haplotypes were found in SEA only and 5% were found in CSA only, indicating that SEA was a major geographic source of EA populations.

Computing 3-D wavefields in mantle circulations models to test hypotheses on the origin of lower mantle heterogeneity under Africa directly against seismic observations

NASA Astrophysics Data System (ADS)

Schuberth, Bernhard; Zaroli, Christophe; Nolet, Guust

2015-04-01

Of particular interest for the tectonic evolution of the Atlantic region is the influence of lower mantle structure under Africa on flow in the upper mantle beneath the ocean basin. Along with its Pacific counterpart, the large African anomaly in the lowermost mantle with strongly reduced seismic velocities has received considerable attention in seismological and geodynamic studies. Several seismological observations are typically taken as an indication that these two anomalies are being caused by large-scale compositional variations and that they are piles of material with higher density than normal mantle rock. This would imply negative buoyancy in the lowermost mantle under Africa, which has important implications for the flow at shallower depth and inferences on the processes that led to the formation of the Atlantic Ocean basin. However, a large number of recent studies argue for a strong thermal gradient across the core-mantle boundary that might provide an alternative explanation for the lower mantle anomaly through the resulting large lateral temperature variations. Recently, we developed a new joint forward modeling approach to test such geodynamic hypotheses directly against the seismic observations: Seismic heterogeneity is predicted by converting the temperature field of a high-resolution 3-D mantle circulation model into seismic velocities using thermodynamic models of mantle mineralogy. 3-D global wave propagation in the synthetic elastic structures is then simulated using a spectral element method. Being based on forward modelling only, this approach allows us to generate synthetic wavefields and seismograms independently of seismic observations. The statistics of observed long-period body wave traveltime variations show a markedly different behaviour for P- and S-waves: the standard deviation of P-wave delay times stays almost constant with ray turning depth, while that of the S-wave delay times increases strongly throughout the mantle. In an earlier study, we showed that synthetic traveltime variations computed for an isochemical mantle circulation model with strong core heating can reproduce these different trends. This was taken as a strong indication that seismic heterogeneity in the lower mantle is likely dominated by thermal variations on large length-scales (i.e., relevant for long-period body waves). We will discuss the robustness of this earlier conclusion by exploring the uncertainties in the mineralogical models used to convert temperatures to seismic velocities. In particular, we investigate the influence of anelasticity on the standard deviation of our synthetic traveltime variations. Owing to the differences in seismic frequency content between laboratory measurements (MHz to GHz) and the Earth (mHz to Hz), the seismic velocities given in the mineralogical model need to be adjusted; that is, corrected for dispersion due to anelastic effects.

FPI observations of nighttime mesospheric and thermospheric winds in China and their comparisons with HWM07

NASA Astrophysics Data System (ADS)

Yuan, Wei

2015-04-01

We analyzed the nighttime horizontal neutral winds in the middle atmosphere (˜87 and ˜98 km) and thermosphere (˜250 km) derived from a Fabry-Perot interferometer (FPI), which was installed at Xinglong station (40.2◦ N, 117.4◦ E) in central China. The wind data covered the period from April 2010 to July 2012. We studied the annual, semiannual and terannual variations of the midnight winds at ˜87 km, ˜98 km and ˜250 km for the first time and compared them with Horizontal Wind Model 2007 (HWM07). Our results show the following: (1) at ˜ 87 km, both the observed and model zonal winds have similar phases in the annual and semiannual variations. However, the HWM07 amplitudes are much larger. (2) At ˜98 km, the model shows strong eastward wind in the summer solstice, resulting in a large annual variation, while the observed strongest component is semiannual. The observation and model midnight meridional winds agree well. Both are equatorward throughout the year and have small amplitudes in the annual and semiannual variations. (3) There are large discrepancies between the observed and HWM07 winds at ˜250 km. This discrepancy is largely due to the strong semiannual zonal wind in the model and the phase difference in the annual variation of the meridional wind. The FPI annual variation coincides with the results from Arecibo, which has similar geomagnetic latitude as Xinglong station. In General, the consistency of FPI winds with model winds is better at ˜87 and ˜98 km than that at ˜250 km. We also studied the seasonally and monthly averaged nighttime winds. The most salient features include the following: (1) the seasonally averaged zonal winds at ˜87 and ˜98 km typically have small variations throughout the night. (2) The model zonal and meridional nighttime wind variations are typically much larger than those of observations at ˜87 km and ˜98 km. (3) At ˜250 km, model zonal wind compares well with the observation in the winter. For spring and autumn, the model wind is more eastward before ˜ 03:00 LT but more westward after. The observed nighttime zonal and meridional winds on average are close to zero in the summer and autumn, which indicates a lack of strong stable tides. The consistency of FPI zonal wind with model wind at ˜250 km is better than the meridional wind.

Satellite microwave observations of the interannual variability of snowmelt on sea ice in the Southern Ocean

NASA Astrophysics Data System (ADS)

Willmes, S.; Haas, C.; Nicolaus, M.; Bareiss, J.

2009-04-01

Snowmelt processes on Antarctic sea ice are examined. We present a simple snowmelt indicator based on diurnal brightness temperature variations from microwave satellite data. The method is validated through extensive field data from the western Weddell Sea and lends itself to the investigation of interannual and spatial variations of the typical snowmelt on Antarctic sea ice. We use in situ measurements of physical snow properties to show that despite the absence of strong melting, the summer period is distinct from all other seasons with enhanced diurnal variations of snow wetness. A microwave emission model reveals that repeated thawing and refreezing causes the typical microwave emissivity signatures that are found on perennial Antarctic sea ice during summer. The proposed melt indicator accounts for the characteristic phenomenological stages of snowmelt in the Southern Ocean and detects the onset of diurnal snow wetting. An algorithm is presented to map large-scale snowmelt onset, based on satellite data from the period between 1988 and 2006. The results indicate strong meridional gradients of snowmelt onset with the Weddell, Amundsen and Ross Seas showing earliest (beginning of October) and most frequent snowmelt. Moreover, a distinct interannual variability of melt onset dates and large areas of first-year ice where no diurnal freeze-thawing occurs at the surface are determined.

Satellite microwave observations of the interannual variability of snowmelt on sea ice in the Southern Ocean

NASA Astrophysics Data System (ADS)

Willmes, Sascha; Haas, Christian; Nicolaus, Marcel; Bareiss, JöRg

2009-03-01

Snowmelt processes on Antarctic sea ice are examined. We present a simple snowmelt indicator based on diurnal brightness temperature variations from microwave satellite data. The method is validated through extensive field data from the western Weddell Sea and lends itself to the investigation of interannual and spatial variations of the typical snowmelt on Antarctic sea ice. We use in-situ measurements of physical snow properties to show that despite the absence of strong melting, the summer period is distinct from all other seasons with enhanced diurnal variations of snow wetness. A microwave emission model reveals that repeated thawing and refreezing cause the typical microwave emissivity signatures that are found on perennial Antarctic sea ice during summer. The proposed melt indicator accounts for the characteristic phenomenological stages of snowmelt in the Southern Ocean and detects the onset of diurnal snow wetting. An algorithm is presented to map large-scale snowmelt onset based on satellite data from the period between 1988 and 2006. The results indicate strong meridional gradients of snowmelt onset with the Weddell, Amundsen, and Ross Seas showing earliest (beginning of October) and most frequent snowmelt. Moreover, a distinct interannual variability of melt onset dates and large areas of first-year ice where no diurnal freeze thawing occurs at the surface are determined.

Interannual Variations in Earth's Low-Degree Gravity Field and the Connections With Geophysical/Climatic Changes

NASA Technical Reports Server (NTRS)

Chao, Benjamin F.; Cox, Christopher M.

2004-01-01

Long-wavelength time-variable gravity recently derived from satellite laser ranging (SLR) analysis have focused to a large extent on the effects of the recent (since 1998) large anomalous change in J2, or the Earth's oblateness, and the potential causes. However, it is relatively more difficult to determine whether there are corresponding signals in the shorter wavelength zonal harmonics from the existing SLR-derived time variable gravity results, although it appears that geophysical fluid mass transport is being observed. For example, the recovered J3 time series shows remarkable agreement with NCEP-derived estimates of atmospheric gravity variations. Likewise, some of the non-zonal spherical harmonic components have significant interannual signal that appears to be related to mass transport. The non-zonal degree-2 components show reasonable temporal correlation with atmospheric signals, as well as climatic effects such as El Nino Southern Oscillation. We will present recent updates on the J2 evolution, as well as a look at other low-degree components of the interannual variations of gravity, complete through degree 4. We will examine the possible geophysical and climatic causes of these low-degree time-variable gravity related to oceanic and hydrological mass transports, for example some anomalous but prominent signals found in the extratropic Pacific ocean related to the Pacific Decadal Oscillation.

Abundances in the red giants of M13 and M22

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lehnert, M.D.; Bell, R.A.; Cohen, J.G.

Abundances of Ca, Na, and Fe are derived for 10 red giant branch stars in the globular clusters M13 and M22, by means of model atmosphere analyses of high-dispersion spectra. It was found that M13 and M22 represent two different types of globular clusters. M13 is similar to M92 and many other globular clusters in that it displays variations in CH and CN band strengths, while showing no variation in either Ca or Fe abundance. The Na abundance was found to vary and its variation correlates with CN band strengths. This suggests that the source of the observed CN bandmore » strength variation is the same as that of the Na variation. M22, on the other hand, is similar to Omega Cen, in that it displays variations in Ca, Na, and Fe abundances, and these variations correlate with variations in CH and CN band strengths. These correlations suggest that the cause of the variations in M22 is largely primordial, and that mixing may only make a relatively small contribution to the C and N variations observed. 61 refs.« less

Variation of atmospheric carbon monoxide over the Arctic Ocean during summer 2012

NASA Astrophysics Data System (ADS)

Park, Keyhong; Siek Rhee, Tae; Emmons, Louisa

2014-05-01

Atmospheric carbon monoxide (CO) plays an important role in ozone-related chemistry in the troposphere, especially under low-NOx conditions like the open ocean. During summer 2012, we performed a continuous high-resolution (0.1Hz) shipboard measurement of atmospheric CO over the Arctic Ocean. We also simulated the observation using a 3-D global chemical transport model (the Model for OZone And Related chemical Tracers-4; MOZART-4) for further analysis of the observed results. In the model, tags for each sources and emission regions of CO are applied and this enables us to delineate the source composition of the observations. Along with the observed variation of CO concentration during the research cruise, we will present in detailed analysis of the variation of source components and change of regional contributions. We found large (~80ppbv) variation of CO concentration in the Arctic Ocean which is mostly influenced by the variation of biomass burning activity. The contribution of anthropogenic emission is limited over the Arctic Ocean, although the northeast Asian anthropogenic emission shows a dominant component of transported anthropogenic CO. Also, our analysis shows, near the Bering Strait, Europe is the main emission region for anthropogenic CO.

Variability of yellow tulp (Moraea pallida Bak.) toxicity.

PubMed

Snyman, L D; Schultz, R A; van den Berg, H

2011-06-01

Yellow tulp (Moraea pallida Bak.), collected predominantly during the flowering stage from a number of sites in South Africa, showed large variation in digoxin equivalent values, indicating variability in yellow tulp toxicity. Very low values were recorded for tulp collected from certain sites in the Northern Cape.

LC-MS analysis of glycoalkaloid diversity among seven potato genotypes

USDA-ARS?s Scientific Manuscript database

Secondary metabolites in potato tubers include both phytonutrients and plant defense compounds. The extent of variation in these small molecules among different potato genotypes is not well characterized. LC-MS analysis of tuber extracts from seven potato genotypes showed that one large source of sm...

Long-term variabilities of meridional geostrophic volumn transport in North Pacific Ocean

NASA Astrophysics Data System (ADS)

Zhou, H.; Yuan, D.; Dewar, W. K.

2016-02-01

The meridional geostrophic volumn transport (MGVT) by the ocean plays a very important role in the climatic water mass and heat balance because of its large heat capacity which enables the oceans to store the large amount of radiation received in the summer and to release it in winter. Better understanding of the role of the oceans in climate variability is essential to assess the likely range of future climate fluctuations. In the last century the North Pacific Ocean experienced considerable climate variability, especially on decadal time scale. Some studies have shown that the North Pacific Ocean is the origin of North Pacific multidecadal variability (Latif and Barnett, 1994; Barnett et al., 1999). These fluctuations were associated with large anomalies in sea level, temperature, storminess and rainfall, the heat transport and other extremes are changing as well. If the MGVT of the ocean is well-determined, it can be used as a test of the validity of numerical, global climate models. In this paper, we investigate the long-term variability of the MGVT in North Pacific ocean based on 55 years long global ocean heat and salt content data (Levitus et al., 2012). Very clear inter-decadal variations can be seen in tropical , subtropical and subpolar regions of North Pacific Ocean. There are very consistent variations between the MGVT anomalies and the inter-decadal pacific oscillation (IPO) index in the tropical gyre with cold phase of IPO corresponding to negative MGVT anomalies and warm phase corresponding to positive MGVT anomalies. The subtropical gyre shows more complex variations, and the subpolar gyre shows a negative MGVT anomaly before late 1970's and a positive anomaly after that time. The geostrophic velocities of North Pacific Ocean show significantly different anomalies during the two IPO cold phases of 1955-1976 and 1999 to present, which suggests a different mechanism of the two cold phases. The long term variations of Sverdrup transport compares well with that of the MGVT in the basin of 8-10N and north of 35N, but the two compares poorly or even reversed in the middle part of the basin. A reduced gravity model is used to investigate the mechanisms of the above variations.

Decomposing functional trait associations in a Chinese subtropical forest

PubMed Central

Pei, Kequan; Kéry, Marc; Niklaus, Pascal A.; Schmid, Bernhard

2017-01-01

Functional traits, properties of organisms correlated with ecological performance, play a central role in plant community assembly and functioning. To some extents, functional traits vary in concert, reflecting fundamental ecological strategies. While “trait syndromes” characteristic of e.g. fast-growing, early-successional vs. competitive, late-successional species are recognized in principle, less is known about the environmental and genetic factors at the source of trait variation and covariation within plant communities. We studied the three leaf traits leaf half-life (LHL), leaf mass per area (LMA) and nitrogen concentration in green leaves (Ngreen) and the wood trait wood density (WD) in 294 individuals belonging to 45 tree or shrub species in a Chinese subtropical forest from September 2006 to January 2009. Using multilevel ANOVA and decomposition of sums of products, we estimated the amount of trait variation and covariation among species (mainly genetic causes), i.e. plant functional type (deciduous vs. evergreen species), growth form (tree vs. shrub species), family/genus/species differences, and within species (mainly environmental causes), i.e. individual and season. For single traits, the variation between functional types and among species within functional types was large, but only LMA and Ngreen varied significantly among families and thus showed phylogenetic signal. Trait variation among individuals within species was small, but large temporal variation due to seasonal effects was found within individuals. We did not find any trait variation related to soil conditions underneath the measured individuals. For pairs of traits, variation between functional types and among species within functional types was large, reflecting a strong evolutionary coordination of the traits, with LMA, LHL and WD being positively correlated among each other and negatively with Ngreen. This integration of traits was consistent with a putative stem-leaf economics spectrum ranging from deciduous species with thin, high-nitrogen leaves and low-density wood to evergreen species with thick, low-nitrogen leaves and dense wood and was not influenced by phylogenetic history. Trait coordination within species was weak, allowing individual trees to deviate from the interspecific trait coordination and thus respond flexibly to environmental heterogeneity. Our findings suggest that within a single woody plant community variation and covariation in functional traits allows a large number of species to co-exist and cover a broad spectrum of multivariate niche space, which in turn may increase total resource extraction by the community and community functioning. PMID:28419169

Toward Precision and Reproducibility of Diffusion Tensor Imaging: A Multicenter Diffusion Phantom and Traveling Volunteer Study.

PubMed

Palacios, E M; Martin, A J; Boss, M A; Ezekiel, F; Chang, Y S; Yuh, E L; Vassar, M J; Schnyer, D M; MacDonald, C L; Crawford, K L; Irimia, A; Toga, A W; Mukherjee, P

2017-03-01

Precision medicine is an approach to disease diagnosis, treatment, and prevention that relies on quantitative biomarkers that minimize the variability of individual patient measurements. The aim of this study was to assess the intersite variability after harmonization of a high-angular-resolution 3T diffusion tensor imaging protocol across 13 scanners at the 11 academic medical centers participating in the Transforming Research and Clinical Knowledge in Traumatic Brain Injury multisite study. Diffusion MR imaging was acquired from a novel isotropic diffusion phantom developed at the National Institute of Standards and Technology and from the brain of a traveling volunteer on thirteen 3T MR imaging scanners representing 3 major vendors (GE Healthcare, Philips Healthcare, and Siemens). Means of the DTI parameters and their coefficients of variation across scanners were calculated for each DTI metric and white matter tract. For the National Institute of Standards and Technology diffusion phantom, the coefficients of variation of the apparent diffusion coefficient across the 13 scanners was <3.8% for a range of diffusivities from 0.4 to 1.1 × 10 -6 mm 2 /s. For the volunteer, the coefficients of variations across scanners of the 4 primary DTI metrics, each averaged over the entire white matter skeleton, were all <5%. In individual white matter tracts, large central pathways showed good reproducibility with the coefficients of variation consistently below 5%. However, smaller tracts showed more variability, with the coefficients of variation of some DTI metrics reaching 10%. The results suggest the feasibility of standardizing DTI across 3T scanners from different MR imaging vendors in a large-scale neuroimaging research study. © 2017 by American Journal of Neuroradiology.

Equivalent input spectrum and drain current spectrum for 1/ƒ noise in short channel MOS transistors

NASA Astrophysics Data System (ADS)

Gentil, P.; Mounib, A.

1981-05-01

Flicker noise in MOS transistors can be evaluated by measuring the spectrum SID of the drain current fluctuation or the spectrum Sve of an equivalent gate fluctuation. We show here that experimental variations of {S I D}/{Sve} are in good agreement with gm2 by considering a model of the transconductance gm which takes into account the variations of the channel carriers mobility with the surface electric field. The model agrees with the experimental results obtained on short channel MOS transistors which exhibit large variations of mobility with the gate voltage. The validity of physical interpretations of noise data on MOS transistors is examined.

Guyana dolphins (Sotalia guianensis) from Costa Rica emit whistles that vary with surface behaviors.

PubMed

May-Collado, Laura J

2013-10-01

Guyana dolphins show remarkable intraspecific whistle variation. This variation has been largely explained in terms of distance among populations; however, other factors such as behavior may also be important. A broadband recording system recorded the whistles of Guyana dolphins under three behavioral states. A discriminant analysis found that during social and travel events, dolphins emit whistles with high delta and minimum frequency, respectively. Whistle duration was also important in discriminating behaviors. This study indicates that behavior is an important factor contributing to whistle variation of Guyana dolphins. Understanding how dolphin whistles vary with behavioral context will advance our understanding of dolphin communication and enable appropriate comparative studies.

Large-scale evidence of dependency length minimization in 37 languages

PubMed Central

Futrell, Richard; Mahowald, Kyle; Gibson, Edward

2015-01-01

Explaining the variation between human languages and the constraints on that variation is a core goal of linguistics. In the last 20 y, it has been claimed that many striking universals of cross-linguistic variation follow from a hypothetical principle that dependency length—the distance between syntactically related words in a sentence—is minimized. Various models of human sentence production and comprehension predict that long dependencies are difficult or inefficient to process; minimizing dependency length thus enables effective communication without incurring processing difficulty. However, despite widespread application of this idea in theoretical, empirical, and practical work, there is not yet large-scale evidence that dependency length is actually minimized in real utterances across many languages; previous work has focused either on a small number of languages or on limited kinds of data about each language. Here, using parsed corpora of 37 diverse languages, we show that overall dependency lengths for all languages are shorter than conservative random baselines. The results strongly suggest that dependency length minimization is a universal quantitative property of human languages and support explanations of linguistic variation in terms of general properties of human information processing. PMID:26240370

Robust Optical Recognition of Cursive Pashto Script Using Scale, Rotation and Location Invariant Approach

PubMed Central

Ahmad, Riaz; Naz, Saeeda; Afzal, Muhammad Zeshan; Amin, Sayed Hassan; Breuel, Thomas

2015-01-01

The presence of a large number of unique shapes called ligatures in cursive languages, along with variations due to scaling, orientation and location provides one of the most challenging pattern recognition problems. Recognition of the large number of ligatures is often a complicated task in oriental languages such as Pashto, Urdu, Persian and Arabic. Research on cursive script recognition often ignores the fact that scaling, orientation, location and font variations are common in printed cursive text. Therefore, these variations are not included in image databases and in experimental evaluations. This research uncovers challenges faced by Arabic cursive script recognition in a holistic framework by considering Pashto as a test case, because Pashto language has larger alphabet set than Arabic, Persian and Urdu. A database containing 8000 images of 1000 unique ligatures having scaling, orientation and location variations is introduced. In this article, a feature space based on scale invariant feature transform (SIFT) along with a segmentation framework has been proposed for overcoming the above mentioned challenges. The experimental results show a significantly improved performance of proposed scheme over traditional feature extraction techniques such as principal component analysis (PCA). PMID:26368566

A statistical approach to detection of copy number variations in PCR-enriched targeted sequencing data.

PubMed

Demidov, German; Simakova, Tamara; Vnuchkova, Julia; Bragin, Anton

2016-10-22

Multiplex polymerase chain reaction (PCR) is a common enrichment technique for targeted massive parallel sequencing (MPS) protocols. MPS is widely used in biomedical research and clinical diagnostics as the fast and accurate tool for the detection of short genetic variations. However, identification of larger variations such as structure variants and copy number variations (CNV) is still being a challenge for targeted MPS. Some approaches and tools for structural variants detection were proposed, but they have limitations and often require datasets of certain type, size and expected number of amplicons affected by CNVs. In the paper, we describe novel algorithm for high-resolution germinal CNV detection in the PCR-enriched targeted sequencing data and present accompanying tool. We have developed a machine learning algorithm for the detection of large duplications and deletions in the targeted sequencing data generated with PCR-based enrichment step. We have performed verification studies and established the algorithm's sensitivity and specificity. We have compared developed tool with other available methods applicable for the described data and revealed its higher performance. We showed that our method has high specificity and sensitivity for high-resolution copy number detection in targeted sequencing data using large cohort of samples.

The records of terrestrial and marine biomarkers in South China Sea EXP349 Sites U1432C and U1433A, B: Implications for East Asian monsoon variability and paleoceanographic variations.

NASA Astrophysics Data System (ADS)

hyun, Sangmin; kim, Songyi

2016-04-01

Marine and terrestrial biomarkers, alkenones and n-alkanes compound, were investigated in sediment taken from the South China Sea (SCS) IODP Sites Exp. U1432C, U1433A and U1433B to evaluate Asian monsoon variability and paleoceanographic variations. Alkenone-based sea surface temperature (SSTalk) from the northern Site (U1432C) ranges from approximately 18.2oC to 28.3oC with an average of 24.4oC (n=65). Estimated SSTalk were slightly higher in the southern Site U1433A than at U1432C. SSTalk in Site U1433A ranges from 24.3oC to 27.4oC with an average 26.1oC (n=32), showing as much as 1.7oC higher SSTs than at U1432C. High concentrations of n-alkanes (nC21-35) are present throughout the Site SC1432C with strong fluctuations in the upper part (average = 496ug/g, n=140). The much higher records at U1433A and U1433B show long-range variations, but the concentration of n-alkanes remains constant below 244mbsf in Site 1433B (less than 200ug/g), suggesting an important change occurred at this horizon, dividing two different environmental domains. These differences in SSTalk and n-alkane concentration between two Sites might not only link with latitudinal location but also the influx of terrestrial biomarker due to the Asian monsoon variability and local oceanographic variations since the last approximately 1.5 Ma. Several indices of Average Chain Length (ACL) and Carbon Preferences Index (ICP) showed large shifts and fluctuations in both Sites. In particular, one of the paleo-plant proxy, Paq, also shows time-dependent large fluctuations in both Sites suggesting long time-scale variations in the flux of terrestrial organic compound as well as paleoclimatic changes in the East Asian area.

Influence of Hybrid Perovskite Fabrication Methods on Film Formation, Electronic Structure, and Solar Cell Performance

PubMed Central

Schnier, Tobias; Emara, Jennifer; Olthof, Selina; Meerholz, Klaus

2017-01-01

Hybrid organic/inorganic halide perovskites have lately been a topic of great interest in the field of solar cell applications, with the potential to achieve device efficiencies exceeding other thin film device technologies. Yet, large variations in device efficiency and basic physical properties are reported. This is due to unintentional variations during film processing, which have not been sufficiently investigated so far. We therefore conducted an extensive study of the morphology and electronic structure of a large number of CH3NH3PbI3 perovskite where we show how the preparation method as well as the mixing ratio of educts methylammonium iodide and lead(II) iodide impact properties like film formation, crystal structure, density of states, energy levels, and ultimately the solar cell performance. PMID:28287555

Hints of correlation between broad-line and radio variations for 3C 120

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, H. T.; Bai, J. M.; Li, S. K.

2014-01-01

In this paper, we investigate the correlation between broad-line and radio variations for the broad-line radio galaxy 3C 120. By the z-transformed discrete correlation function method and the model-independent flux randomization/random subset selection (FR/RSS) Monte Carlo method, we find that broad Hβ line variations lead the 15 GHz variations. The FR/RSS method shows that the Hβ line variations lead the radio variations by a factor of τ{sub ob} = 0.34 ± 0.01 yr. This time lag can be used to locate the position of the emitting region of radio outbursts in the jet, on the order of ∼5 lt-yr frommore » the central engine. This distance is much larger than the size of the broad-line region. The large separation of the radio outburst emitting region from the broad-line region will observably influence the gamma-ray emission in 3C 120.« less

The influence of the Atlantic Warm Pool on the Florida panhandle sea breeze

USGS Publications Warehouse

Misra, V.; Moeller, L.; Stefanova, L.; Chan, S.; O'Brien, J. J.; Smith, T.J.; Plant, N.

2011-01-01

In this paper we examine the variations of the boreal summer season sea breeze circulation along the Florida panhandle coast from relatively high resolution (10 km) regional climate model integrations. The 23 year climatology (1979-2001) of the multidecadal dynamically downscaled simulations forced by the National Centers for Environmental Prediction-Department of Energy (NCEP-DOE) Reanalysis II at the lateral boundaries verify quite well with the observed climatology. The variations at diurnal and interannual time scales are also well simulated with respect to the observations. We show from composite analyses made from these downscaled simulations that sea breezes in northwestern Florida are associated with changes in the size of the Atlantic Warm Pool (AWP) on interannual time scales. In large AWP years when the North Atlantic Subtropical High becomes weaker and moves further eastward relative to the small AWP years, a large part of the southeast U.S. including Florida comes under the influence of relatively strong anomalous low-level northerly flow and large-scale subsidence consistent with the theory of the Sverdrup balance. This tends to suppress the diurnal convection over the Florida panhandle coast in large AWP years. This study is also an illustration of the benefit of dynamic downscaling in understanding the low-frequency variations of the sea breeze. Copyright 2011 by the American Geophysical Union.

Temporal and spatial variations of soil carbon dioxide, methane, and nitrous oxide fluxes in a Southeast Asian tropical rainforest

NASA Astrophysics Data System (ADS)

Itoh, M.; Kosugi, Y.; Takanashi, S.; Hayashi, Y.; Kanemitsu, S.; Osaka, K.; Tani, M.; Nik, A. R.

2010-09-01

To clarify the factors controlling temporal and spatial variations of soil carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) fluxes, we investigated these gas fluxes and environmental factors in a tropical rainforest in Peninsular Malaysia. Temporal variation of CO2 flux in a 2-ha plot was positively related to soil water condition and rainfall history. Spatially, CO2 flux was negatively related to soil water condition. When CO2 flux hotspots were included, no other environmental factors such as soil C or N concentrations showed any significant correlation. Although the larger area sampled in the present study complicates explanations of spatial variation of CO2 flux, our results support a previously reported bipolar relationship between the temporal and spatial patterns of CO2 flux and soil water condition observed at the study site in a smaller study plot. Flux of CH4 was usually negative with little variation, resulting in the soil at our study site functioning as a CH4 sink. Both temporal and spatial variations of CH4 flux were positively related to the soil water condition. Soil N concentration was also related to the spatial distribution of CH4 flux. Some hotspots were observed, probably due to CH4 production by termites, and these hotspots obscured the relationship between both temporal and spatial variations of CH4 flux and environmental factors. Temporal variation of N2O flux and soil N2O concentration was large and significantly related to the soil water condition, or in a strict sense, to rainfall history. Thus, the rainfall pattern controlled wet season N2O production in soil and its soil surface flux. Spatially, large N2O emissions were detected in wet periods at wetter and anaerobic locations, and were thus determined by soil physical properties. Our results showed that, even in Southeast Asian rainforests where distinct dry and wet seasons do not exist, variation in the soil water condition related to rainfall history controlled the temporal variations of soil CO2 flux, CH4 uptake, and N2O emission. The soil water condition associated with soil hydraulic properties was also the important controlling factor of the spatial distributions of these gas fluxes.

Anomalous variations of lithosphere magnetic field before several earthquakes

NASA Astrophysics Data System (ADS)

Ni, Z.; Chen, B.

2015-12-01

Based on the geomagnetic vector data measured each year since 2011 at more than 500 sites with a mean spatial interval of ~70km.we observed anomalous variations of lithospheric magnetic field before and after over 15 earthquakes having magnitude > 5. We find that the field in near proximity (about 50km) to the epicenter of large earthquakes shows high spatial and temporal gradients before the earthquake. Due to the low frequency of repeat measurements it is unclear when these variations occurred and how do them evolve. We point out anomalous magnetic filed using some circles with radius of 50km usually in June of each year, and then we would check whether quake will locat in our circles during one year after that time (June to next June). Now we caught 10 earthquakes of 15 main shocks having magnitude > 5, most of them located at less than10km away from our circles and some of them were in our circles. Most results show that the variations of lithosphere magnetic filed at the epicenter are different with surrending backgroud usually. When we figure out horizontal variations (vector) of lithosphere magnetic field and epicenter during one year after each June, we found half of them show that the earthquakes will locat at "the inlands in a flowing river", that means earthquakes may occur at "quiet"regions while the backgroud show character as"flow" as liquid. When we compared with GPS results, it appears that these variations of lithospere magnetic field may also correlate with displacement of earth's surface. However we do not compared with GPS results for each earthquake, we are not clear whether these anomalous variations of lithospere magnetic field may also correlate with anomalous displacement of earth's surface. Future work will include developing an automated method for identifying this type of anomalous field behavior and trying to short repeat measurement period to 6 month to try to find when these variations occur.

Improvement of the quality of work in a biochemistry laboratory via measurement system analysis.

PubMed

Chen, Ming-Shu; Liao, Chen-Mao; Wu, Ming-Hsun; Lin, Chih-Ming

2016-10-31

An adequate and continuous monitoring of operational variations can effectively reduce the uncertainty and enhance the quality of laboratory reports. This study applied the evaluation rule of the measurement system analysis (MSA) method to estimate the quality of work conducted in a biochemistry laboratory. Using the gauge repeatability & reproducibility (GR&R) approach, variations in quality control (QC) data among medical technicians in conducting measurements of five biochemical items, namely, serum glucose (GLU), aspartate aminotransferase (AST), uric acid (UA), sodium (Na) and chloride (Cl), were evaluated. The measurements of the five biochemical items showed different levels of variance among the different technicians, with the variances in GLU measurements being higher than those for the other four items. The ratios of precision-to-tolerance (P/T) for Na, Cl and GLU were all above 0.5, implying inadequate gauge capability. The product variation contribution of Na was large (75.45% and 31.24% in normal and abnormal QC levels, respectively), which showed that the impact of insufficient usage of reagents could not be excluded. With regard to reproducibility, high contributions (of more than 30%) of variation for the selected items were found. These high operator variation levels implied that the possibility of inadequate gauge capacity could not be excluded. The analysis of variance (ANOVA) of GR&R showed that the operator variations in GLU measurements were significant (F=5.296, P=0.001 in the normal level and F=3.399, P=0.015 in the abnormal level, respectively). In addition to operator variations, product variations of Na were also significant for both QC levels. The heterogeneity of variance for the five technicians showed significant differences for the Na and Cl measurements in the normal QC level. The accuracy of QC for five technicians was identified for further operational improvement. This study revealed that MSA can be used to evaluate product and personnel errors and to improve the quality of work in a biochemical laboratory through proper corrective actions.

SPATIALLY RESOLVED SPECTROSCOPY OF EUROPA’S LARGE-SCALE COMPOSITIONAL UNITS AT 3–4 μ m WITH KECK NIRSPEC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fischer, P. D.; Brown, M. E.; Trumbo, S. K.

2017-01-01

We present spatially resolved spectroscopic observations of Europa’s surface at 3–4 μ m obtained with the near-infrared spectrograph and adaptive optics system on the Keck II telescope. These are the highest quality spatially resolved reflectance spectra of Europa’s surface at 3–4 μ m. The observations spatially resolve Europa’s large-scale compositional units at a resolution of several hundred kilometers. The spectra show distinct features and geographic variations associated with known compositional units; in particular, large-scale leading hemisphere chaos shows a characteristic longward shift in peak reflectance near 3.7 μ m compared to icy regions. These observations complement previous spectra of large-scalemore » chaos, and can aid efforts to identify the endogenous non-ice species.« less

The roles of convective entrainment in spatial distributions and temporal variations of precipitation over tropical oceans

NASA Astrophysics Data System (ADS)

Hirota, N.; Takayabu, Y. N.; Watanabe, M.; Kimoto, M.; Chikira, M.

2013-12-01

This study shows that a proper treatment of convective entrainment is essential in determining spatial distributions and temporal variations of precipitation by numerical experiments. They have performed and compared four experiments with different entrainment characteristics: a control (Ctl), no entrainment (NoEnt), original Arakawa Schubert (AS), and AS with simple empirical suppression of convection (ASRH). The fractional entrainment rate of AS and ASRH are constant for each cloud type and are very small near cloud base compared to Ctl, in which half of buoyancy-generated energy is consumed by the entrainment. Ctl well reproduces the spatial and temporal variations, whereas NoEnt and AS, which are very similar to each other, significantly underestimated the variations with the so-called the double ITCZ problem. The enhanced variations in Ctl are due to the larger entrainment that strengthens the coupling of convection and free tropospheric humidity. Time variations are also more realistic in Ctl; mid-height convection moistens mid-troposphere and large precipitation events occur after sufficient moisture is available. In contrast, deep convection is more frequent but with smaller precipitation amount in NoEnt and AS. ASRH shows smaller spatial but excessive temporal variations suggesting that its empirical suppression condition is too simple and a more sophisticated formulation is required for more realistic precipitation variations. This study was supported by the Ministry of Education, Culture, Sports, Science and Technology (GRENE), and by the Ministry of the Environment (2A-1201), Japan.

Dielectric studies on PEG-LTMS based polymer composites

NASA Astrophysics Data System (ADS)

Patil, Ravikumar V.; Praveen, D.; Damle, R.

2018-02-01

PEG LTMS based polymer composites were prepared and studied for dielectric constant variation with frequency and temperature as a potential candidate with better dielectric properties. Solution cast technique is used for the preparation of polymer composite with five different compositions. Samples show variation in dielectric constant with frequency and temperature. Dielectric constant is large at low frequencies and higher temperatures. Samples with larger space charges have shown larger dielectric constant. The highest dielectric constant observed was about 29244 for PEG25LTMS sample at 100Hz and 312 K.

Nursing home bed capacity in the States, 1978-86

PubMed Central

Harrington, Charlene; Swan, James H.; Grant, Leslie A.

1988-01-01

Trends in nursing home bed supply in the States show large variations in beds per population and a gradual decline in supply per aged population. A cross-sectional time-series regression analysis was used to examine some factors associated with nursing home bed supply. Variation was accounted for by economic factors, supply of alternative services, and climate. State Medicaid reimbursement rates had negative coefficients, with supply suggesting States may be increasing rates to improve access where supply is limited. Medicaid waiver policy was not found to be significant. PMID:10312634

The importance of work organization on workload and musculoskeletal health--Grocery store work as a model.

PubMed

Balogh, I; Ohlsson, K; Nordander, C; Björk, J; Hansson, G-Å

2016-03-01

We have evaluated the consequences of work organization on musculoskeletal health. Using a postal questionnaire, answered by 1600 female grocery store workers, their main work tasks were identified and four work groups were defined (cashier, picking, and delicatessen work, and a mixed group, who performed a mix of these tasks). The crude odds ratios (ORs) for neck/shoulder complaints were 1.5 (95% CI 1.0-2.2), 1.1 (0.7-1.5) and 1.6 (1.1-2.3), respectively, compared to mixed work. Adjusting for individual and psychosocial factors had no effect on these ORs. For elbows/hands, no significant differences were found. Technical measurements of the workload showed large differences between the work groups. Picking work was the most strenuous, while cashier work showed low loads. Quantitative measures of variation revealed for mixed work high between minutes variation and the highest between/within minutes variation. Combining work tasks with different physical exposure levels increases the variation and may reduce the risk of musculoskeletal complaints. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

A preliminary investigation of finite-element modeling for composite rotor blades

NASA Technical Reports Server (NTRS)

Lake, Renee C.; Nixon, Mark W.

1988-01-01

The results from an initial phase of an in-house study aimed at improving the dynamic and aerodynamic characteristics of composite rotor blades through the use of elastic couplings are presented. Large degree of freedom shell finite element models of an extension twist coupled composite tube were developed and analyzed using MSC/NASTRAN. An analysis employing a simplified beam finite element representation of the specimen with the equivalent engineering stiffness was additionally performed. Results from the shell finite element normal modes and frequency analysis were compared to those obtained experimentally, showing an agreement within 13 percent. There was appreciable degradation in the frequency prediction for the torsional mode, which is elastically coupled. This was due to the absence of off-diagonal coupling terms in the formulation of the equivalent engineering stiffness. Parametric studies of frequency variation due to small changes in ply orientation angle and ply thickness were also performed. Results showed linear frequency variations less than 2 percent per 1 degree variation in the ply orientation angle, and 1 percent per 0.0001 inch variation in the ply thickness.

BOLE WATER CONTENT SHOWS LITTLE SEASONAL VARIATION IN CENTURY-OLD DOUGLAS-FIR TREES

EPA Science Inventory

Purportedly, large Douglas-fir trees in the American Pacific Northwest use water stored in bole tissues to ameliorate the effects of seasonal summer drought, the water content of bole tissues being drawn down over the summer months and replenished during the winter. Continuous mo...

Functional genomics analysis of big data identifies novel PPARy target SNPs showing association with cardio metabolic outcomes

USDA-ARS?s Scientific Manuscript database

Background - Cardiovascular disease and type-2-diabetes represent overlapping diseases where a large portion of the variation attributable to genetics remains unexplained. An important player in their etiology is Peroxisome Proliferator-activated Receptor gamma (PPARy) that is involved in lipid and ...

Vesta Mineralogy after Dawn Global Observations

NASA Technical Reports Server (NTRS)

ChristinaDeSanctis, Maria; Ammannito, E.; Capaccioni, F.; Cparia, M. T.; Carraro, F.; Fonte, S.; Frigeri, A.; Longobardo, A.; Marchi, S.; Palomba, E.;

Time- and sediment depth-related variations in bacterial diversity and community structure in subtidal sands.

PubMed

Böer, Simone I; Hedtkamp, Stefanie I C; van Beusekom, Justus E E; Fuhrman, Jed A; Boetius, Antje; Ramette, Alban

2009-07-01

Bacterial community structure and microbial activity were determined together with a large number of contextual environmental parameters over 2 years in subtidal sands of the German Wadden Sea in order to identify the main factors shaping microbial community structure and activity in this habitat. Seasonal changes in temperature were directly reflected in bacterial activities and total community respiration, but could not explain variations in the community structure. Strong sediment depth-related patterns were observed for bacterial abundances, carbon production rates and extracellular enzymatic activities. Bacterial community structure also showed a clear vertical variation with higher operational taxonomic unit (OTU) numbers at 10-15 cm depth than in the top 10 cm, probably because of the decreasing disturbance by hydrodynamic forces with sediment depth. The depth-related variations in bacterial community structure could be attributed to vertical changes in bacterial abundances, chlorophyll a and NO(3)(-), indicating that spatial patterns of microbes are partially environmentally controlled. Time was the most important single factor affecting microbial community structure with an OTU replacement of up to 47% over 2 years and a contribution of 34% to the total variation. A large part of this variation was not related to any environmental parameters, suggesting that temporal variations in bacterial community structure are caused by yet unknown environmental drivers and/or by stochastic events in coastal sand habitats. Principal ecosystem functions such as benthic oxygen consumption and extracellular hydrolysis of organic matter were, however, at a high level at all times, indicating functional redundancy in the microbial communities.

Geographical Variation in Egg Mass and Egg Content in a Passerine Bird

PubMed Central

Ruuskanen, Suvi; Siitari, Heli; Eeva, Tapio; Belskii, Eugen; Järvinen, Antero; Kerimov, Anvar; Krams, Indrikis; Moreno, Juan; Morosinotto, Chiara; Mänd, Raivo; Möstl, Erich; Orell, Markku; Qvarnström, Anna; Salminen, Juha-Pekka; Slater, Fred; Tilgar, Vallo; Visser, Marcel E.; Winkel, Wolfgang; Zang, Herwig; Laaksonen, Toni

2011-01-01

Reproductive, phenotypic and life-history traits in many animal and plant taxa show geographic variation, indicating spatial variation in selection regimes. Maternal deposition to avian eggs, such as hormones, antibodies and antioxidants, critically affect development of the offspring, with long-lasting effects on the phenotype and fitness. Little is however known about large-scale geographical patterns of variation in maternal deposition to eggs. We studied geographical variation in egg components of a passerine bird, the pied flycatcher (Ficedula hypoleuca), by collecting samples from 16 populations and measuring egg and yolk mass, albumen lysozyme activity, yolk immunoglobulins, yolk androgens and yolk total carotenoids. We found significant variation among populations in most egg components, but ca. 90% of the variation was among individuals within populations. Population however explained 40% of the variation in carotenoid levels. In contrast to our hypothesis, we found geographical trends only in carotenoids, but not in any of the other egg components. Our results thus suggest high within-population variation and leave little scope for local adaptation and genetic differentiation in deposition of different egg components. The role of these maternally-derived resources in evolutionary change should be further investigated. PMID:22110579

Monsoon rainfall over India in June and link with northwest tropical pacific - June ISMR and link with northwest tropical pacific

NASA Astrophysics Data System (ADS)

Surendran, Sajani; Gadgil, Sulochana; Rajendran, Kavirajan; Varghese, Stella Jes; Kitoh, Akio

2018-03-01

Recent years have witnessed large interannual variation of all-India rainfall (AIR) in June, with intermittent large deficits and excesses. Variability of June AIR is found to have the strongest link with variation of rainfall over northwest tropical Pacific (NWTP), with AIR deficit (excess) associated with enhancement (suppression) of NWTP rainfall. This association is investigated using high-resolution Meteorological Research Institute model which shows high skill in simulating important features of Asian summer monsoon, its variability and the inverse relationship between NWTP rainfall and AIR. Analysis of the variation of NWTP rainfall shows that it is associated with a change in the latitudinal position of subtropical westerly jet over the region stretching from West of Tibetan Plateau (WTP) to NWTP and the phase of Rossby wave steered in it with centres over NWTP and WTP. In years with large rainfall excess/deficit, the strong link between AIR and NWTP rainfall exists through differences in Rossby wave phase steered in the jet. The positive phase of the WTP-NWTP pattern, with troughs over WTP and west of NWTP, tends to be associated with increased rainfall over NWTP and decreased AIR. This scenario is reversed in the opposite phase. Thus, the teleconnection between NWTP rainfall and AIR is a manifestation of the difference in the phase of Rossby wave between excess and deficit years, with centres over WTP and NWTP. This brings out the importance of prediction of phase of Rossby waves over WTP and NWTP in advance, for prediction of June rainfall over India.

Two distinct patterns of seasonal variation of airborne black carbon over Tibetan Plateau

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Mo; Xu, Baiqing; Wang, Ninglian

Airborne black carbon (BC) mass concentrations were measured from November 2012 to June 2013 at Ranwu and Beiluhe, located in the southeastern and central Tibetan Plateau, respectively. Monthly mean BC concentrations showawinter (November–February) high (413.2 ng m $-$3) and spring (March–June) low(139.1 ng m $-$3) at Ranwu, but in contrast awinter lowand spring high at Beiluhe (204.8 and 621.6 ng m $-$3, respectively). By examining the meteorological conditions at various scales, we found that themonthly variation of airborne BC over the southeastern Tibetan Plateau (TP) was highly influenced by regional precipitation and over the hinterland by winds. Local precipitation atmore » both sites showed little impact on the seasonal variation of airborne BC concentrations. Potential BC source regions are identified using air mass backward trajectory analysis. At Ranwu, BC was dominated by the air masses from the northeastern India and Bangladesh in both winter and spring, whereas at Beiluhe it was largely contributed by air masses from the south slope of Himalayas in winter, and from the arid region in the north of the TP in spring. Thewinter and spring seasonal peak of BC in the southern TP is largely contributed by emissions from South Asia, and this seasonal variation is heavily influenced by the regional monsoon. In the northern TP, BC had high concentrations during spring and summer seasons, which is very likely associated with more efficient transport of BC over the arid regions on the north of Tibetan Plateau and in Central Asia. Airborne BC concentrations at the Ranwusampling site showed a significant diurnal cyclewith a peak shortly after sunrise followed by a decrease before noon in both winter and spring, likely shaped by local human activities and the diurnal variation of wind speed. At the Beiluhe sampling site, the diurnal variation of BC is different and less distinct.« less

Strange Beta: Chaotic Variations for Indoor Rock Climbing Route Setting

NASA Astrophysics Data System (ADS)

Phillips, Caleb; Bradley, Elizabeth

2011-04-01

In this paper we apply chaotic systems to the task of sequence variation for the purpose of aiding humans in setting indoor rock climbing routes. This work expands on prior work where similar variations were used to assist in dance choreography and music composition. We present a formalization for transcription of rock climbing problems and a variation generator that is tuned for this domain and addresses some confounding problems, including a new approach to automatic selection of initial conditions. We analyze our system with a large blinded study in a commercial climbing gym in cooperation with experienced climbers and expert route setters. Our results show that our system is capable of assisting a human setter in producing routes that are at least as good as, and in some cases better than, those produced traditionally.

Background levels of methane in Mars’ atmosphere show strong seasonal variations

NASA Astrophysics Data System (ADS)

Webster, Christopher R.; Mahaffy, Paul R.; Atreya, Sushil K.; Moores, John E.; Flesch, Gregory J.; Malespin, Charles; McKay, Christopher P.; Martinez, German; Smith, Christina L.; Martin-Torres, Javier; Gomez-Elvira, Javier; Zorzano, Maria-Paz; Wong, Michael H.; Trainer, Melissa G.; Steele, Andrew; Archer, Doug; Sutter, Brad; Coll, Patrice J.; Freissinet, Caroline; Meslin, Pierre-Yves; Gough, Raina V.; House, Christopher H.; Pavlov, Alexander; Eigenbrode, Jennifer L.; Glavin, Daniel P.; Pearson, John C.; Keymeulen, Didier; Christensen, Lance E.; Schwenzer, Susanne P.; Navarro-Gonzalez, Rafael; Pla-García, Jorge; Rafkin, Scot C. R.; Vicente-Retortillo, Álvaro; Kahanpää, Henrik; Viudez-Moreiras, Daniel; Smith, Michael D.; Harri, Ari-Matti; Genzer, Maria; Hassler, Donald M.; Lemmon, Mark; Crisp, Joy; Sander, Stanley P.; Zurek, Richard W.; Vasavada, Ashwin R.

2018-06-01

Variable levels of methane in the martian atmosphere have eluded explanation partly because the measurements are not repeatable in time or location. We report in situ measurements at Gale crater made over a 5-year period by the Tunable Laser Spectrometer on the Curiosity rover. The background levels of methane have a mean value 0.41 ± 0.16 parts per billion by volume (ppbv) (95% confidence interval) and exhibit a strong, repeatable seasonal variation (0.24 to 0.65 ppbv). This variation is greater than that predicted from either ultraviolet degradation of impact-delivered organics on the surface or from the annual surface pressure cycle. The large seasonal variation in the background and occurrences of higher temporary spikes (~7 ppbv) are consistent with small localized sources of methane released from martian surface or subsurface reservoirs.

Longitudinal dependence of the seasonal variations of the topside ionospheric and plasmaspheric electron content: observations and model results

NASA Astrophysics Data System (ADS)

Zhang, Man-Lian; Liu, Libo; Ning, Baiqi; Wan, Weixing

2016-07-01

Radio signals transmitted from GPS satellite going through the ionization zone above the Earth will be refracted by the ionized components in the ionosphere and the plasmasphere, which would produce additional transfer delay and generate extra errors in satellite navigation and positioning, etc. These errors have strong relation with the total electron content (TEC) along the signal's travelling path. Therefore TEC is one of the most important parameters required by many users for different modern usage purposes. The topside ionospheric and plasmaspheric electron content makes a large contribution to TEC. In the present study, data for the year 2008 of the topside ionospheric and plasmaspheric electron content (PEC) between the height of 800-20200km above the Earth derived from the upward-looking TEC measurements of the precise orbit determination antenna on board the COSMIC low Earth orbit (LEO) satellites to the GPS signals are used to study the longitudinal dependence of the seasonal variations of PEC. A comparison study of the observed PEC with the IZMIRAN_Plas model results is also made. Our study showed that PEC shows different seasonal variations at different longitudinal sectors: for the 240°E-60°E longitudinal sector, PEC shows a strong annual variation with lowest value in the June solstice and highest value in the December solstice months; In contrast, very weak seasonal variations are observed for PEC at 60°E-240°E longitudinal sector; Comparison study showed that this longitudinal dependence feature of the observed PEC's seasonal variation is not well captured by the IZMIRAN_Plas model result. Acknowledgments This research was supported by the National Natural Science Foundation of China (NSFC No. 41274163)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kataria, T.; Showman, A. P.; Fortney, J. J.

We present three-dimensional atmospheric circulation models of GJ 1214b, a 2.7 Earth-radius, 6.5 Earth-mass super Earth detected by the MEarth survey. Here we explore the planet's circulation as a function of atmospheric metallicity and atmospheric composition, modeling atmospheres with a low mean molecular weight (MMW; i.e., H{sub 2}-dominated) and a high MMW (i.e., water- and CO{sub 2}-dominated). We find that atmospheres with a low MMW have strong day-night temperature variations at pressures above the infrared photosphere that lead to equatorial superrotation. For these atmospheres, the enhancement of atmospheric opacities with increasing metallicity lead to shallower atmospheric heating, larger day-night temperaturemore » variations, and hence stronger superrotation. In comparison, atmospheres with a high MMW have larger day-night and equator-to-pole temperature variations than low MMW atmospheres, but differences in opacity structure and energy budget lead to differences in jet structure. The circulation of a water-dominated atmosphere is dominated by equatorial superrotation, while the circulation of a CO{sub 2}-dominated atmosphere is instead dominated by high-latitude jets. By comparing emergent flux spectra and light curves for 50× solar and water-dominated compositions, we show that observations in emission can break the degeneracy in determining the atmospheric composition of GJ 1214b. The variation in opacity with wavelength for the water-dominated atmosphere leads to large phase variations within water bands and small phase variations outside of water bands. The 50× solar atmosphere, however, yields small variations within water bands and large phase variations at other characteristic wavelengths. These observations would be much less sensitive to clouds, condensates, and hazes than transit observations.« less

Variation in Women's Preferences Regarding Male Facial Masculinity Is Better Explained by Genetic Differences Than by Previously Identified Context-Dependent Effects.

PubMed

Zietsch, Brendan P; Lee, Anthony J; Sherlock, James M; Jern, Patrick

2015-09-01

Women's preferences for masculine versus feminine male faces are highly variable. According to a dominant theory in evolutionary psychology, this variability results from adaptations that optimize preferences by calibrating them to certain contextual factors, including women's self-perceived attractiveness, short- versus long-term relationship orientation, pathogen disgust sensitivity, and stage of the menstrual cycle. The theory does not account for the possible contribution of genetic variation on women's facial masculinity preference. Using a large sample (N = 2,160) of identical and nonidentical female Finnish twins and their siblings, we showed that the proportion of variation in women's preferences regarding male facial masculinity that was attributable to genetic variation (38%) dwarfed the variation due to the combined effect of contextual factors (< 1%). These findings cast doubt on the importance of these context-dependent effects and may suggest a need for refocusing in the field toward understanding the wide genetic variation in these preferences and how this variation relates to the evolution of sexual dimorphism in faces. © The Author(s) 2015.

Estimating variation in stomatal frequency at intra-individual, intra-site, and inter-taxonomic levels in populations of the Leonardoxa africana (Fabaceae) complex over environmental gradients in Cameroon

NASA Astrophysics Data System (ADS)

Finsinger, Walter; Dos Santos, Thibaut; McKey, Doyle

2013-07-01

Variation of stomatal frequency (stomatal density and stomatal index) includes genetically-based, potentially-adaptive variation, and variation due to phenotypic plasticity, the degree of which may be fundamental to the ability to maintain high water-use efficiency and thus to deal with environmental change. We analysed stomatal frequency and morphology (pore length, pore width) in leaves from several individuals from nine populations of four sub-species of the Leonardoxa africana complex. The dataset represents a hierarchical sampling wherein factors are nested within each level (leaves in individuals, individuals in sites, etc.), allowing estimation of the contribution of different levels to overall variation, using variance-component analysis. SI showed significant variation among sites ("site" is largely confounded with "sub-species"), being highest in the sub-species localized in the highest-elevation site. However, most of the observed variance was accounted for at intra-site and intra-individual levels. This variance could reflect great phenotypic plasticity, presumably in response to highly local variation in micro-environmental conditions.

Multi-model analysis of terrestrial carbon cycles in Japan: limitations and implications of model calibration using eddy flux observations

NASA Astrophysics Data System (ADS)

Ichii, K.; Suzuki, T.; Kato, T.; Ito, A.; Hajima, T.; Ueyama, M.; Sasai, T.; Hirata, R.; Saigusa, N.; Ohtani, Y.; Takagi, K.

2010-07-01

Terrestrial biosphere models show large differences when simulating carbon and water cycles, and reducing these differences is a priority for developing more accurate estimates of the condition of terrestrial ecosystems and future climate change. To reduce uncertainties and improve the understanding of their carbon budgets, we investigated the utility of the eddy flux datasets to improve model simulations and reduce variabilities among multi-model outputs of terrestrial biosphere models in Japan. Using 9 terrestrial biosphere models (Support Vector Machine - based regressions, TOPS, CASA, VISIT, Biome-BGC, DAYCENT, SEIB, LPJ, and TRIFFID), we conducted two simulations: (1) point simulations at four eddy flux sites in Japan and (2) spatial simulations for Japan with a default model (based on original settings) and a modified model (based on model parameter tuning using eddy flux data). Generally, models using default model settings showed large deviations in model outputs from observation with large model-by-model variability. However, after we calibrated the model parameters using eddy flux data (GPP, RE and NEP), most models successfully simulated seasonal variations in the carbon cycle, with less variability among models. We also found that interannual variations in the carbon cycle are mostly consistent among models and observations. Spatial analysis also showed a large reduction in the variability among model outputs. This study demonstrated that careful validation and calibration of models with available eddy flux data reduced model-by-model differences. Yet, site history, analysis of model structure changes, and more objective procedure of model calibration should be included in the further analysis.

SU-F-T-70: A High Dose Rate Total Skin Electron Irradiation Technique with A Specific Inter-Film Variation Correction Method for Very Large Electron Beam Fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, X; Rosenfield, J; Dong, X

2016-06-15

Purpose: Rotational total skin electron irradiation (RTSEI) is used in the treatment of cutaneous T-cell lymphoma. Due to inter-film uniformity variations the dosimetry measurement of a large electron beam of a very low energy is challenging. This work provides a method to improve the accuracy of flatness and symmetry for a very large treatment field of low electron energy used in dual beam RTSEI. Methods: RTSEI is delivered by dual angles field a gantry of ±20 degrees of 270 to cover the upper and the lower halves of the patient body with acceptable beam uniformity. The field size is inmore » the order of 230cm in vertical height and 120 cm in horizontal width and beam energy is a degraded 6 MeV (6 mm of PMMA spoiler). We utilized parallel plate chambers, Gafchromic films and OSLDs as a measuring devices for absolute dose, B-Factor, stationary and rotational percent depth dose and beam uniformity. To reduce inter-film dosimetric variation we introduced a new specific correction method to analyze beam uniformity. This correction method uses some image processing techniques combining film value before and after radiation dose to compensate the inter-variation dose response differences among films. Results: Stationary and rotational depth of dose demonstrated that the Rp is 2 cm for rotational and the maximum dose is shifted toward the surface (3mm). The dosimetry for the phantom showed that dose uniformity reduced to 3.01% for the vertical flatness and 2.35% for horizontal flatness after correction thus achieving better flatness and uniformity. The absolute dose readings of calibrated films after our correction matched with the readings from OSLD. Conclusion: The proposed correction method for Gafchromic films will be a useful tool to correct inter-film dosimetric variation for the future clinical film dosimetry verification in very large fields, allowing the optimizations of other parameters.« less

The rotation of the Sun: Observations at Stanford. [using the Doppler effect

NASA Technical Reports Server (NTRS)

Scherrer, J. M.; Wilcox, J. M.; Svalgaard, L.

1980-01-01

Daily observations of the photospheric rotation rate using the Doppler effect made at the Stanford Solar Observatory since May 1976 are analyzed. Results show that these observations show no daily or long period variations in the rotation rate that exceed the observational error of about one percent. The average rotation rate is the same as that of the sunspot and the large-scale magnetic field structures.

Spatial distribution of aerosol black carbon over India during pre-monsoon season

NASA Astrophysics Data System (ADS)

Beegum, S. Naseema; Moorthy, K. Krishna; Babu, S. Suresh; Satheesh, S. K.; Vinoj, V.; Badarinath, K. V. S.; Safai, P. D.; Devara, P. C. S.; Singh, Sacchidanand; Vinod; Dumka, U. C.; Pant, P.

Aerosol black carbon (BC) mass concentrations ([BC]), measured continuously during a mutli-platform field experiment, Integrated Campaign for Aerosols gases and Radiation Budget (ICARB, March-May 2006), from a network of eight observatories spread over geographically distinct environments of India, (which included five mainland stations, one highland station, and two island stations (one each in Arabian Sea and Bay of Bengal)) are examined for their spatio-temporal characteristics. During the period of study, [BC] showed large variations across the country, with values ranging from 27 μg m -3 over industrial/urban locations to as low as 0.065 μg m -3 over the Arabian Sea. For all mainland stations, [BC] remained high compared to highland as well as island stations. Among the island stations, Port Blair (PBR) had higher concentration of BC, compared to Minicoy (MCY), implying more absorbing nature of Bay of Bengal aerosols than Arabian Sea. The highland station Nainital (NTL), in the central Himalayas, showed low values of [BC], comparable or even lower than that of the island station PBR, indicating the prevalence of cleaner environment over there. An examination of the changes in the mean temporal features, as the season advances from winter (December-February) to pre-monsoon (March-May), revealed that: (a) Diurnal variations were pronounced over all the mainland stations, with an afternoon low and a nighttime high; (b) At the islands, the diurnal variations, though resembled those over the mainlands, were less pronounced; and (c) In contrast to this, highland station showed an opposite pattern with an afternoon high and a late night or early morning low. The diurnal variations at all stations are mainly caused by the dynamics of local Atmospheric Boundary Layer (ABL). At the entire mainland as well as island stations (except HYD and DEL), [BC] showed a decreasing trend from January to May. This is attributed to the increased convective mixing and to the resulting enhanced vertical dispersal of species in the ABL. In addition, large short-period modulations were observed at DEL and HYD, which appeared to be episodic. An examination of this in the light of the MODIS-derived fire count data over India along with the back-trajectory analysis revealed that advection of BC from extensive forest fires and biomass-burning regions upwind were largely responsible for this episodic enhancement in BC at HYD and DEL.

Implications of High Molecular Divergence of Nuclear rRNA and Phylogenetic Structure for the Dinoflagellate Prorocentrum (Dinophyceae, Prorocentrales).

PubMed

Boopathi, Thangavelu; Faria, Daphne Georgina; Cheon, Ju-Yong; Youn, Seok Hyun; Ki, Jang-Seu

2015-01-01

The small and large nuclear subunit molecular phylogeny of the genus Prorocentrum demonstrated that the species are dichotomized into two clades. These two clades were significantly different (one-factor ANOVA, p < 0.01) with patterns compatible for both small and large subunit Bayesian phylogenetic trees, and for a larger taxon sampled dinoflagellate phylogeny. Evaluation of the molecular divergence levels showed that intraspecies genetic variations were significantly low (t-test, p < 0.05), than those for interspecies variations (> 2.9% and > 26.8% dissimilarity in the small and large subunit [D1/D2], respectively). Based on the calculated molecular divergence, the genus comprises two genetically distinct groups that should be considered as two separate genera, thereby setting the pace for major systematic changes for the genus Prorocentrum sensu Dodge. Moreover, the information presented in this study would be useful for improving species identification, detection of novel clades from environmental samples. © 2015 The Author(s) Journal of Eukaryotic Microbiology © 2015 International Society of Protistologists.

Inter-annual and decadal changes in teleconnections drive continental-scale synchronization of tree reproduction.

PubMed

Ascoli, Davide; Vacchiano, Giorgio; Turco, Marco; Conedera, Marco; Drobyshev, Igor; Maringer, Janet; Motta, Renzo; Hacket-Pain, Andrew

2017-12-20

Climate teleconnections drive highly variable and synchronous seed production (masting) over large scales. Disentangling the effect of high-frequency (inter-annual variation) from low-frequency (decadal trends) components of climate oscillations will improve our understanding of masting as an ecosystem process. Using century-long observations on masting (the MASTREE database) and data on the Northern Atlantic Oscillation (NAO), we show that in the last 60 years both high-frequency summer and spring NAO, and low-frequency winter NAO components are highly correlated to continent-wide masting in European beech and Norway spruce. Relationships are weaker (non-stationary) in the early twentieth century. This finding improves our understanding on how climate variation affects large-scale synchronization of tree masting. Moreover, it supports the connection between proximate and ultimate causes of masting: indeed, large-scale features of atmospheric circulation coherently drive cues and resources for masting, as well as its evolutionary drivers, such as pollination efficiency, abundance of seed dispersers, and natural disturbance regimes.

Markov-modulated Markov chains and the covarion process of molecular evolution.

PubMed

Galtier, N; Jean-Marie, A

2004-01-01

The covarion (or site specific rate variation, SSRV) process of biological sequence evolution is a process by which the evolutionary rate of a nucleotide/amino acid/codon position can change in time. In this paper, we introduce time-continuous, space-discrete, Markov-modulated Markov chains as a model for representing SSRV processes, generalizing existing theory to any model of rate change. We propose a fast algorithm for diagonalizing the generator matrix of relevant Markov-modulated Markov processes. This algorithm makes phylogeny likelihood calculation tractable even for a large number of rate classes and a large number of states, so that SSRV models become applicable to amino acid or codon sequence datasets. Using this algorithm, we investigate the accuracy of the discrete approximation to the Gamma distribution of evolutionary rates, widely used in molecular phylogeny. We show that a relatively large number of classes is required to achieve accurate approximation of the exact likelihood when the number of analyzed sequences exceeds 20, both under the SSRV and among site rate variation (ASRV) models.

The surface urban heat island response to urban expansion: A panel analysis for the conterminous United States

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xiaoma; Zhou, Yuyu; Asrar, Ghassem R.

Abstract: Urban heat island (UHI), a major concern worldwide, affects human health and energy use. With current and anticipated rapid urbanization, improved understanding of the response of UHI to urbanization is important for impact analysis and developing effective adaptation measures and mitigation strategies. Current studies mainly focus on a single or a few big cities and knowledge on the response of UHI to urbanization for large areas is very limited. Modelling UHI caused by urbanization for large areas that encompass multiple metropolitans remains a major scientific challenge/opportunity. As a major indicator of urbanization, urban area size lends itself well formore » representation in prognostic models to investigate the impacts of urbanization on UHI and the related socioeconomic and environmental effects. However, we have little knowledge on how UHI responds to the increase of urban area size, namely urban expansion, and its spatial and temporal variation over large areas. In this study, we investigated the relationship between surface UHI (SUHI) and urban area size in the climate and ecological context, and its spatial and temporal variations, based on a panel analysis of about 5000 urban areas of 10 km2 or larger, in the conterminous U.S. We found statistically significant positive relationship between SUHI and urban area size, and doubling the urban area size led to a SUHI increase of higher than 0.7 °C. The response of SUHI to the increase of urban area size shows spatial and temporal variations, with stronger SUHI increase in the Northern region of U.S., and during daytime and summer. Urban area size alone can explain as much as 87% of the variance of SUHI among cities studied, but with large spatial and temporal variations. Urban area size shows higher association with SUHI in regions where the thermal characteristics of land cover surrounding the urban are more homogeneous, such as in Eastern U.S., and in the summer months. This study provides a practical approach for large-scale assessment and modeling of the impact of urbanization on SUHI, both spatially and temporally, for developing mitigation/adaptation measures, especially in anticipated warmer climate conditions for the rest of this century.« less

Effects of Be acceptors on the spin polarization of carriers in p-i-n resonant tunneling diodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Awan, I. T.; Galvão Gobato, Y.; Galeti, H. V. A.

In this paper, we have investigated the effect of Be acceptors on the electroluminescence and the spin polarization in GaAs/AlAs p-i-n resonant tunneling diodes. The quantum well emission comprise two main lines separated by ∼20 meV attributed to excitonic and Be-related transitions, which intensities show remarkably abrupt variations at critical voltages, particularly at the electron resonant peak where it shows a high-frequency bistability. The circular-polarization degree of the quantum-well electroluminescence also shows strong and abrupt variations at the critical bias voltages and it attains relatively large values (of ∼−75% at 15 T). These effects may be explored to design novel devices formore » spintronic applications such as a high-frequency spin-oscillators.« less

Derivation of GPS TEC and receiver bias for Langkawi station in Malaysia

NASA Astrophysics Data System (ADS)

Teh, W. L.; Chen, W. S.; Abdullah, M.

2017-05-01

This paper presents the polynomial-type TEC model to derive total electron content (TEC) and receiver bias for Langkawi (LGKW) station in Malaysia at geographic latitude of 6.32° and longitude of 99.85°. The model uses a polynomial function of coordinates of the ionospheric piercing point to describe the TEC distribution in space. In the model, six polynomial coefficients and a receiver bias are unknown which can be solved by the least squares method. A reasonable agreement is achieved for the derivation of TEC and receiver bias for IENG station in Italy, as compared with that derived by the IGS analysis center, CODE. We process one year of LGKW data in 2010 and show the monthly receiver bias and the seasonal TEC variation. The monthly receiver bias varies between -48 and -24 TECu (1016 electrons/m2), with the mean value at -37 TECu. Large variations happen in the monthly receiver biases due to the low data coverage of high satellite elevation angle (60° < α ≤ 90°). Post-processing TEC approach is implemented which can resolve the wavy pattern of the monthly TEC baseline resulted from the large variation of the receiver bias. The seasonal TEC variation at LGKW exhibits a semi-annual variation, where the peak occurs during equinoctial months, and the trough during summer and winter months.

Small-scale open ocean currents have large effects on wind wave heights

NASA Astrophysics Data System (ADS)

Ardhuin, Fabrice; Gille, Sarah T.; Menemenlis, Dimitris; Rocha, Cesar B.; Rascle, Nicolas; Chapron, Bertrand; Gula, Jonathan; Molemaker, Jeroen

2017-06-01

Tidal currents and large-scale oceanic currents are known to modify ocean wave properties, causing extreme sea states that are a hazard to navigation. Recent advances in the understanding and modeling capability of open ocean currents have revealed the ubiquitous presence of eddies, fronts, and filaments at scales 10-100 km. Based on realistic numerical models, we show that these structures can be the main source of variability in significant wave heights at scales less than 200 km, including important variations down to 10 km. Model results are consistent with wave height variations along satellite altimeter tracks, resolved at scales larger than 50 km. The spectrum of significant wave heights is found to be of the order of 70>>2/>(g2>>2>) times the current spectrum, where >> is the spatially averaged significant wave height, >> is the energy-averaged period, and g is the gravity acceleration. This variability induced by currents has been largely overlooked in spite of its relevance for extreme wave heights and remote sensing.