Intraseasonal to interannual variations in the tropical wave activity revealed in reanalyses and their potential impact on the QBO

NASA Astrophysics Data System (ADS)

Kim, Young-Ha; Yoo, Changhyun

2017-04-01

We investigate activities of tropical waves represented in reanalysis products. The wave activities are quantified by the Eliassen-Palm (EP) flux at 100 hPa, after decomposed into the following four components: equatorially trapped Kelvin waves and mixed Rossby-gravity waves, gravity waves, and Rossby waves. Monthly EP fluxes of the four waves exhibit considerable temporal variations at intraseasonal and interannual, along with seasonal, time scales. These variations are discussed with the tropical large-scale variabilities, including the Madden-Julian Oscillation (MJO), the El Ninõ-Southern Oscillation, and the stratospheric quasi-biennial oscillation (QBO). We find that during boreal winter, the interannual variation of Kelvin wave activity is in phase with that of the MJO amplitude, while such a simultaneous variation cannot be seen in other seasons. The gravity wave is dominated by a semi-annual cycle, while the departure from its semi-annual cycle is largely correlated with the QBO phase in the stratosphere. Potential impacts of the variations in the wave activity upon the QBO properties will be assessed using a simple one-dimensional QBO model.

SOS response and its regulation on the fluoroquinolone resistance.

PubMed

Qin, Ting-Ting; Kang, Hai-Quan; Ma, Ping; Li, Peng-Peng; Huang, Lin-Yan; Gu, Bing

2015-12-01

Bacteria can survive fluoroquinolone antibiotics (FQs) treatment by becoming resistant through a genetic change-mutation or gene acquisition. The SOS response is widespread among bacteria and exhibits considerable variation in its composition and regulation, which is repressed by LexA protein and derepressed by RecA protein. Here, we take a comprehensive review of the SOS gene network and its regulation on the fluoroquinolone resistance. As a unique survival mechanism, SOS may be an important factor influencing the outcome of antibiotic therapy in vivo.

SOS response and its regulation on the fluoroquinolone resistance

PubMed Central

Qin, Ting-Ting; Kang, Hai-Quan; Ma, Ping; Li, Peng-Peng; Huang, Lin-Yan

2015-01-01

Bacteria can survive fluoroquinolone antibiotics (FQs) treatment by becoming resistant through a genetic change—mutation or gene acquisition. The SOS response is widespread among bacteria and exhibits considerable variation in its composition and regulation, which is repressed by LexA protein and derepressed by RecA protein. Here, we take a comprehensive review of the SOS gene network and its regulation on the fluoroquinolone resistance. As a unique survival mechanism, SOS may be an important factor influencing the outcome of antibiotic therapy in vivo. PMID:26807413

Genetic diversity in three endangered pitcher plant species (Sarracenia; Sarraceniaceae) is lower than widespread congeners.

PubMed

Furches, M Steven; Small, Randall L; Furches, Anna

2013-10-01

Narrow-ranging, rare species often exhibit levels of genetic diversity lower than more common or widespread congeners. These taxa are at increased risk of extinction due to threats associated with natural as well as anthropogenic events. We assessed genetic variation in three federally endangered Sarracenia species. We discuss maintenance of genetic diversity and evolutionary implications of rarity. • We analyzed three noncoding chloroplast regions and nine microsatellite loci in populations spanning the geographic ranges of S. oreophila, S. alabamensis, and S. jonesii. The same microsatellite loci were used to examine a single field site of three more widespread species (S. alata, S. leucophylla, and S. rubra subsp. wherryi). • All three endangered species have experienced reductions in population size and numbers. All show considerably less variation than more widespread members of the genus. Sarracenia alabamensis maintains the greatest microsatellite variation but has the fewest remaining populations and may be under the greatest threat. More widespread S. oreophila maintains surprising chloroplast diversity, yet exhibits little microsatellite diversity. Sarracenia jonesii lacks chloroplast diversity, yet maintains greater microsatellite diversity than S. oreophila. • The three endangered species differ in levels and structure of diversity, yet not in predictable ways, emphasizing that unique demographic and ecological histories, rather than current distribution and population size, best explain present patterns of genetic variation. Maintenance of remaining genetic variation is important, but preventing further habitat loss and degradation is critical.

Low-Value Service Use in Provider Organizations.

PubMed

Schwartz, Aaron L; Zaslavsky, Alan M; Landon, Bruce E; Chernew, Michael E; McWilliams, J Michael

2018-02-01

To assess whether provider organizations exhibit distinct profiles of low-value service provision. 2007-2011 Medicare fee-for-service claims and enrollment data. Use of 31 services that provide minimal clinical benefit was measured for 4,039,733 beneficiaries served by 3,137 provider organizations. Variation across organizations, persistence within organizations over time, and correlations in use of different types of low-value services within organizations were estimated via multilevel modeling, with adjustment for beneficiary sociodemographic and clinical characteristics. Organizations provided 45.6 low-value services per 100 beneficiaries on average, with considerable variation across organizations (90th/10th percentile ratio, 1.78; 95 percent CI, 1.72-1.84), including substantial between-organization variation within hospital referral regions (90th/10th percentile ratio, 1.66; 95 percent CI, 1.60-1.71). Low-value service use within organizations was highly correlated over time (r, 0.98; 95 percent CI, 0.97-0.99) and positively correlated between 13 of 15 pairs of service categories (average r, 0.26; 95 percent CI, 0.24-0.28), with the greatest correlation between low-value imaging and low-value cardiovascular testing and procedures (r, 0.54). Use of low-value services in provider organizations exhibited substantial variation, high persistence, and modest consistency across service types. These findings are consistent with organizations shaping the practice patterns of affiliated physicians. © Health Research and Educational Trust.

Tissue Variability and Antennas for Power Transfer to Wireless Implantable Medical Devices.

PubMed

Bocan, Kara N; Mickle, Marlin H; Sejdic, Ervin

2017-01-01

The design of effective transcutaneous systems demands the consideration of inevitable variations in tissue characteristics, which vary across body areas, among individuals, and over time. The purpose of this paper was to design and evaluate several printed antenna topologies for ultrahigh frequency (UHF) transcutaneous power transfer to implantable medical devices, and to investigate the effects of variations in tissue properties on dipole and loop topologies. Here, we show that a loop antenna topology provides the greatest achievable gain with the smallest implanted antenna, while a dipole system provides higher impedance for conjugate matching and the ability to increase gain with a larger external antenna. In comparison to the dipole system, the loop system exhibits greater sensitivity to changes in tissue structure and properties in terms of power gain, but provides higher gain when the separation is on the order of the smaller antenna dimension. The dipole system was shown to provide higher gain than the loop system at greater implant depths for the same implanted antenna area, and was less sensitive to variations in tissue properties and structure in terms of power gain at all investigated implant depths. The results show the potential of easily-fabricated, low-cost printed antenna topologies for UHF transcutaneous power, and the importance of environmental considerations in choosing the antenna topology.

Tissue Variability and Antennas for Power Transfer to Wireless Implantable Medical Devices

PubMed Central

Bocan, Kara N.; Mickle, Marlin H.

2017-01-01

The design of effective transcutaneous systems demands the consideration of inevitable variations in tissue characteristics, which vary across body areas, among individuals, and over time. The purpose of this paper was to design and evaluate several printed antenna topologies for ultrahigh frequency (UHF) transcutaneous power transfer to implantable medical devices, and to investigate the effects of variations in tissue properties on dipole and loop topologies. Here, we show that a loop antenna topology provides the greatest achievable gain with the smallest implanted antenna, while a dipole system provides higher impedance for conjugate matching and the ability to increase gain with a larger external antenna. In comparison to the dipole system, the loop system exhibits greater sensitivity to changes in tissue structure and properties in terms of power gain, but provides higher gain when the separation is on the order of the smaller antenna dimension. The dipole system was shown to provide higher gain than the loop system at greater implant depths for the same implanted antenna area, and was less sensitive to variations in tissue properties and structure in terms of power gain at all investigated implant depths. The results show the potential of easily-fabricated, low-cost printed antenna topologies for UHF transcutaneous power, and the importance of environmental considerations in choosing the antenna topology. PMID:29018637

Sex ratio variation shapes the ecological effects of a globally introduced freshwater fish

PubMed Central

Fryxell, David C.; Arnett, Heather A.; Apgar, Travis M.; Kinnison, Michael T.; Palkovacs, Eric P.

2015-01-01

Sex ratio and sexual dimorphism have long been of interest in population and evolutionary ecology, but consequences for communities and ecosystems remain untested. Sex ratio could influence ecological conditions whenever sexual dimorphism is associated with ecological dimorphism in species with strong ecological interactions. We tested for ecological implications of sex ratio variation in the sexually dimorphic western mosquitofish, Gambusia affinis. This species causes strong pelagic trophic cascades and exhibits substantial variation in adult sex ratios. We found that female-biased populations induced stronger pelagic trophic cascades compared with male-biased populations, causing larger changes to key community and ecosystem responses, including zooplankton abundance, phytoplankton abundance, productivity, pH and temperature. The magnitude of such effects indicates that sex ratio is important for mediating the ecological role of mosquitofish. Because both sex ratio variation and sexual dimorphism are common features of natural populations, our findings should encourage broader consideration of the ecological significance of sex ratio variation in nature, including the relative contributions of various sexually dimorphic traits to these effects. PMID:26490793

Unusual dynamics of extinction in a simple ecological model.

PubMed Central

Sinha, S; Parthasarathy, S

1996-01-01

Studies on natural populations and harvesting biological resources have led to the view, commonly held, that (i) populations exhibiting chaotic oscillations run a high risk of extinction; and (ii) a decrease in emigration/exploitation may reduce the risk of extinction. Here we describe a simple ecological model with emigration/depletion that shows behavior in contrast to this. This model displays unusual dynamics of extinction and survival, where populations growing beyond a critical rate can persist within a band of high depletion rates, whereas extinction occurs for lower depletion rates. Though prior to extinction at lower depletion rates the population exhibits chaotic dynamics with large amplitudes of variation and very low minima, at higher depletion rates the population persists at chaos but with reduced variation and increased minima. For still higher values, within the band of persistence, the dynamics show period reversal leading to stability. These results illustrate that chaos does not necessarily lead to population extinction. In addition, the persistence of populations at high depletion rates has important implications in the considerations of strategies for the management of biological resources. PMID:8643661

Tunneling calculations for GaAs-Al(x)Ga(1-x) as graded band-gap sawtooth superlattices. Thesis

NASA Technical Reports Server (NTRS)

Forrest, Kathrine A.; Meijer, Paul H. E.

1991-01-01

Quantum mechanical tunneling calculations for sawtooth (linearly graded band-gap) and step-barrier AlGaAs superlattices were performed by means of a transfer matrix method, within the effective mass approximation. The transmission coefficient and tunneling current versus applied voltage were computed for several representative structures. Particular consideration was given to effective mass variations. The tunneling properties of step and sawtooth superlattices show some qualitative similarities. Both structures exhibit resonant tunneling, however, because they deform differently under applied fields, the J-V curves differ.

Dynamic Vertical Profiles of Peat Porewater Chemistry in a Northern Peatland

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

Griffiths, Natalie A.; Sebestyen, Stephen D.

We measured pH, cations, nutrients, and total organic carbon (TOC) over 3 years to examine weekly to monthly variability in porewater chemistry depth profiles (0–3.0 m) in an ombrotrophic bog in Minnesota, USA. We also compared temporal variation at one location to spatial variation in depth profiles at 16 locations across the bog. Most solutes exhibited large gradients with depth. pH increased by two units and calcium concentrations increased over 20 fold with depth, and may reflect peatland development from minerotrophic to ombrotrophic conditions. Ammonium concentrations increased almost 20 fold and TOC concentrations decreased by half with depth, and thesemore » patterns likely reflect mineralization of peat or decomposition of TOC. There was also considerable temporal variation in the porewater chemistry depth profiles. Ammonium, soluble reactive phosphorus, and potassium showed greater temporal variation in near-surface porewater, while pH, calcium, and TOC varied more at depth. This variation demonstrates that deep peat porewater chemistry is not static. Lastly, temporal variation in solute chemistry depth profiles was greater than spatial variation in several instances, especially in shallow porewaters. In conclusion, characterizing both temporal and spatial variability is necessary to ensure representative sampling in peatlands, especially when calculating solute pools and fluxes and parameterizing process-based models.« less

Dynamic Vertical Profiles of Peat Porewater Chemistry in a Northern Peatland

DOE PAGES

Griffiths, Natalie A.; Sebestyen, Stephen D.

2016-10-14

We measured pH, cations, nutrients, and total organic carbon (TOC) over 3 years to examine weekly to monthly variability in porewater chemistry depth profiles (0–3.0 m) in an ombrotrophic bog in Minnesota, USA. We also compared temporal variation at one location to spatial variation in depth profiles at 16 locations across the bog. Most solutes exhibited large gradients with depth. pH increased by two units and calcium concentrations increased over 20 fold with depth, and may reflect peatland development from minerotrophic to ombrotrophic conditions. Ammonium concentrations increased almost 20 fold and TOC concentrations decreased by half with depth, and thesemore » patterns likely reflect mineralization of peat or decomposition of TOC. There was also considerable temporal variation in the porewater chemistry depth profiles. Ammonium, soluble reactive phosphorus, and potassium showed greater temporal variation in near-surface porewater, while pH, calcium, and TOC varied more at depth. This variation demonstrates that deep peat porewater chemistry is not static. Lastly, temporal variation in solute chemistry depth profiles was greater than spatial variation in several instances, especially in shallow porewaters. In conclusion, characterizing both temporal and spatial variability is necessary to ensure representative sampling in peatlands, especially when calculating solute pools and fluxes and parameterizing process-based models.« less

Genome-wide DNA methylation alterations of Alternanthera philoxeroides in natural and manipulated habitats: implications for epigenetic regulation of rapid responses to environmental fluctuation and phenotypic variation.

PubMed

Gao, Lexuan; Geng, Yupeng; Li, Bo; Chen, Jiakuan; Yang, Ji

2010-11-01

Alternanthera philoxeroides (alligator weed) is an invasive weed that can colonize both aquatic and terrestrial habitats. Individuals growing in different habitats exhibit extensive phenotypic variation but little genetic differentiation in its introduced range. The mechanisms underpinning the wide range of phenotypic variation and rapid adaptation to novel and changing environments remain uncharacterized. In this study, we examined the epigenetic variation and its correlation with phenotypic variation in plants exposed to natural and manipulated environmental variability. Genome-wide methylation profiling using methylation-sensitive amplified fragment length polymorphism (MSAP) revealed considerable DNA methylation polymorphisms within and between natural populations. Plants of different source populations not only underwent significant morphological changes in common garden environments, but also underwent a genome-wide epigenetic reprogramming in response to different treatments. Methylation alterations associated with response to different water availability were detected in 78.2% (169/216) of common garden induced polymorphic sites, demonstrating the environmental sensitivity and flexibility of the epigenetic regulatory system. These data provide evidence of the correlation between epigenetic reprogramming and the reversible phenotypic response of alligator weed to particular environmental factors. © 2010 Blackwell Publishing Ltd.

Variations in working memory capacity predict individual differences in general learning abilities among genetically diverse mice.

PubMed

Kolata, Stefan; Light, Kenneth; Townsend, David A; Hale, Gregory; Grossman, Henya C; Matzel, Louis D

2005-11-01

Up to 50% of an individuals' performance across a wide variety of distinct cognitive tests can be accounted for by a single factor (i.e., "general intelligence"). Despite its ubiquity, the processes or mechanisms regulating this factor are a matter of considerable debate. Although it has been hypothesized that working memory may impact cognitive performance across various domains, tests have been inconclusive due to the difficulty in isolating working memory from its overlapping operations, such as verbal ability. We address this problem using genetically diverse mice, which exhibit a trait analogous to general intelligence. The general cognitive abilities of CD-1 mice were found to covary with individuals' working memory capacity, but not with variations in long-term retention. These results provide evidence that independent of verbal abilities, variations in working memory are associated with general cognitive abilities, and further, suggest a conservation across species of mechanisms and/or processes that regulate cognitive abilities.

Genomics of parallel adaptation at two timescales in Drosophila

PubMed Central

Begun, David J.

2017-01-01

Two interesting unanswered questions are the extent to which both the broad patterns and genetic details of adaptive divergence are repeatable across species, and the timescales over which parallel adaptation may be observed. Drosophila melanogaster is a key model system for population and evolutionary genomics. Findings from genetics and genomics suggest that recent adaptation to latitudinal environmental variation (on the timescale of hundreds or thousands of years) associated with Out-of-Africa colonization plays an important role in maintaining biological variation in the species. Additionally, studies of interspecific differences between D. melanogaster and its sister species D. simulans have revealed that a substantial proportion of proteins and amino acid residues exhibit adaptive divergence on a roughly few million years long timescale. Here we use population genomic approaches to attack the problem of parallelism between D. melanogaster and a highly diverged conger, D. hydei, on two timescales. D. hydei, a member of the repleta group of Drosophila, is similar to D. melanogaster, in that it too appears to be a recently cosmopolitan species and recent colonizer of high latitude environments. We observed parallelism both for genes exhibiting latitudinal allele frequency differentiation within species and for genes exhibiting recurrent adaptive protein divergence between species. Greater parallelism was observed for long-term adaptive protein evolution and this parallelism includes not only the specific genes/proteins that exhibit adaptive evolution, but extends even to the magnitudes of the selective effects on interspecific protein differences. Thus, despite the roughly 50 million years of time separating D. melanogaster and D. hydei, and despite their considerably divergent biology, they exhibit substantial parallelism, suggesting the existence of a fundamental predictability of adaptive evolution in the genus. PMID:28968391

Ecological association between HIV and concurrency point-prevalence in South Africa's ethnic groups.

PubMed

Kenyon, Chris

2013-11-01

HIV prevalence between different ethnic groups within South Africa exhibits considerable variation. Numerous authors believe that elevated sexual partner concurrency rates are important in the spread of HIV. Few studies have, however, investigated if differential concurrency rates could explain differential HIV spread within ethnic groups in South Africa. This ecological analysis, explores how much of the variation in HIV prevalence by ethnic group is explained by differential concurrency rates. Using a nationally representative survey (the South African National HIV Prevalence, HIV Incidence, Behaviour and Communication Survey, 2005) the HIV prevalence in each of eight major ethnic groups was calculated. Linear regression analysis was used to assess the association between an ethnic group's HIV prevalence and the point-prevalence of concurrency. Results showed that HIV prevalence rates varied considerably between South Africa's ethnic groups. This applied to both different racial groups and to different ethnic groups within the black group. The point-prevalence of concurrency by ethnic group was strongly associated with HIV prevalence (R(2) = 0.83; p = 0.001). Tackling the key drivers of high HIV transmission in this population may benefit from more emphasis on partner reduction interventions.

Magnetic properties of Co-based multilayers with layer-alloyed modulations

NASA Astrophysics Data System (ADS)

Poulopoulos, P.; Angelakeris, M.; Niarchos, D.; Krishnan, R.; Porte, M.; Batas, C.; Flevaris, N. K.

1995-07-01

Various types of Co-based multilayers such as Pt mCo n, Pt m[CoPt] n, Co m[CoPd] n and Co m[CoPt] n were prepared by e-gun evaporation. Strong perpendicular anisotropy with considerable coercivity of ˜ 1 kOe was found for PtCo samples with thin Co layers. Moreover, the magnetization of Pt m[CoPt] n samples was found to approach that of pure Co and in the case of n > 5 enhancement of 30% or more exhibited. Magnetic properties were found to be strongly influenced by variations of modulation parameters.

Electrorotation and levitation of cells and colloidal particles

PubMed Central

Foster, Kenneth R.; Sauer, Friedrich A.; Schwan, Herman P.

1992-01-01

We review dielectrophoretic forces on cells and colloidal particles, emphasizing their use for manipulating and characterizing the electrical properties of suspended particles. Compared with dielectric spectroscopy, these methods offer a measure of independence from electrode artifacts and mixture theory. On the assumption that the particles can be modeled as uniform dielectric objects with effective dielectric properties, a simple theory can be developed for the frequency variation in the field-induced forces. For particles exhibiting counterion polarization, dielectrophoretic forces differ considerably from predictions of this theory at low frequencies, apparently because of double layer phenomena. PMID:19431839

The functional correlation between rainfall rate and extinction coefficient for frequencies from 3 to 10 GHz

NASA Technical Reports Server (NTRS)

Jameson, A. R.

1990-01-01

The relationship between the rainfall rate (R) obtained from radiometric brightness temperatures and the extinction coefficient (k sub e) is investigated by computing the values of k sub e over a wide range of rainfall rates, for frequencies from 3 to 25 GHz. The results show that the strength of the relation between the R and the k sub e values exhibits considerable variation for frequencies at this range. Practical suggestions are made concerning the selection of particular frequencies for rain measurements to minimize the error in R determinations.

Investigating aerosol properties in Peninsular Malaysia via the synergy of satellite remote sensing and ground-based measurements

NASA Astrophysics Data System (ADS)

Kanniah, Kasturi Devi; Lim, Hui Qi; Kaskaoutis, Dimitris G.; Cracknell, Arthur P.

2014-03-01

Spatio-temporal variation and trends in atmospheric aerosols as well as their impact on solar radiation and clouds are crucial for regional and global climate change assessment. These topics are not so well-documented over Malaysia, the fact that it receives considerable amounts of pollutants from both local and trans-boundary sources. The present study aims to analyse the spatio-temporal evolution and decadal trend of Aerosol Optical Depth (AOD) from Terra and Aqua MODIS sensors, to identify different types and origin of aerosols and explore the link between aerosols and solar radiation. AOD and fine-mode fraction (FMF) products from MODIS, AOD and Ångström Exponent (AE) values from AERONET stations along with ground-based PM10 measurements and solar radiation recordings at selected sites in Peninsular Malaysia are used for this scope. The MODIS AODs exhibit a wide spatio-temporal variation over Peninsular Malaysia, while Aqua AOD is consistently lower than that from Terra. The AOD shows a neutral-to-declining trend during the 2000s (Terra satellite), while that from Aqua exhibits an increasing trend (~ 0.01 per year). AERONET AODs exhibit either insignificant diurnal variation or higher values during the afternoon, while their short-term availability does not allow for a trend analysis. Moreover, the PM10 concentrations exhibit a general increasing trend over the examined locations. The sources and destination of aerosols are identified via the HYSPLIT trajectory model, revealing that aerosols during the dry season (June to September) are mainly originated from the west and southwest (Sumatra, Indonesia), while in the wet season (November to March) they are mostly associated with the northeast monsoon winds from the southern China Sea. Different aerosol types are identified via the relationship of AOD with FMF, revealing that the urban and biomass-burning aerosols are the most abundant over the region contributing to a significant reduction (~- 0.21 MJ m- 2) of the solar radiation.

An in vitro study of anti-inflammatory activity of standardised Andrographis paniculata extracts and pure andrographolide.

PubMed

Low, Mitchell; Khoo, Cheang S; Münch, Gerald; Govindaraghavan, Suresh; Sucher, Nikolaus J

2015-02-07

The anti-inflammatory activity of Andrographis paniculata (Acanthaceae), a traditional medicine widely used in Asia, is commonly attributed to andrographolide, its main secondary metabolite. Commercial A. paniculata extracts are standardised to andrographolide content. We undertook the present study to investigate 1) how selective enrichment of andrographolide in commercial A. paniculata extracts affects the variability of non-standardised phytochemical components and 2) if variability in the non-standardised components of the extract affects the pharmacological activity of andrographolide itself. We characterized 12 commercial, standardised (≥30% andrographolide) batches of A. paniculata extracts from India by HPLC profiling. We determined the antioxidant capacity of the extracts using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging, oxygen radical antioxidant capacity (ORAC) and a Folin-Ciocalteu (FC) antioxidant assays. Their anti-inflammatory activity was assessed by assaying their inhibitory effect on the release of tumor necrosis factor alpha (TNF-α) in the human monocytic cell line THP-1. The andrographolide content in the samples was close to the claimed value (32.2 ± 2.1%, range 27.5 to 35.9%). Twenty-one non-standardised constituents exhibited more than 2-fold variation in HPLC peak intensities in the tested batches. The chlorogenic acid content of the batches varied more than 30-fold. The DPPH free radical scavenging activity varied ~3-fold, the ORAC and FC antioxidant capacity varied ~1.5 fold among batches. In contrast, the TNF-α inhibitory activity of the extracts exhibited little variation and comparison with pure andrographolide indicated that it was mostly due to their andrographolide content. Standardised A. paniculata extracts contained the claimed amount of andrographolide but exhibited considerable phytochemical background variation. DPPH radical scavenging activity of the extracts was mostly due to the flavonoid/phenlycarboxylic acid compounds in the extracts. The inhibitory effect of andrographolide on the release of TNF-α was little affected by the quantitative variation of the non-standardised constituents.

Spatial and temporal variability of microgeographic genetic structure in white-tailed deer

USGS Publications Warehouse

Scribner, Kim T.; Smith, Michael H.; Chesser, Ronald K.

1997-01-01

Techniques are described that define contiguous genetic subpopulations of white-tailed deer (Odocoileus virginianus) based on the spatial dispersion of 4,749 individuals that possessed discrete character values (alleles or genotypes) during each of 6 years (1974-1979). White-tailed deer were not uniformly distributed in space, but exhibited considerable spatial genetic structuring. Significant non-random clusters of individuals were documented during each year based on specific alleles and genotypes at the Sdh locus. Considerable temporal variation was observed in the position and genetic composition of specific clusters, which reflected changes in allele frequency in small geographic areas. The position of clusters did not consistently correspond with traditional management boundaries based on major discontinuities in habitat (swamp versus upland) and hunt compartments that were defined by roads and streams. Spatio-temporal stability of observed genetic contiguous clusters was interpreted relative to method and intensity of harvest, movements, and breeding ecology.

Express yourself: bold individuals induce enhanced morphological defences

PubMed Central

Hulthén, Kaj; Chapman, Ben B.; Nilsson, P. Anders; Hollander, Johan; Brönmark, Christer

2014-01-01

Organisms display an impressive array of defence strategies in nature. Inducible defences (changes in morphology and/or behaviour within a prey's lifetime) allow prey to decrease vulnerability to predators and avoid unnecessary costs of expression. Many studies report considerable interindividual variation in the degree to which inducible defences are expressed, yet what underlies this variation is poorly understood. Here, we show that individuals differing in a key personality trait also differ in the magnitude of morphological defence expression. Crucian carp showing risky behaviours (bold individuals) expressed a significantly greater morphological defence response when exposed to a natural enemy when compared with shy individuals. Furthermore, we show that fish of different personality types differ in their behavioural plasticity, with shy fish exhibiting greater absolute plasticity than bold fish. Our data suggest that individuals with bold personalities may be able to compensate for their risk-prone behavioural type by expressing enhanced morphological defences. PMID:24335987

A New Occurrence Model for National Assessment of Undiscovered Volcanogenic Massive Sulfide Deposits

USGS Publications Warehouse

Shanks, W.C. Pat; Dusel-Bacon, Cynthia; Koski, Randolph; Morgan, Lisa A.; Mosier, Dan; Piatak, Nadine M.; Ridley, Ian; Seal, Robert R.; Schulz, Klaus J.; Slack, John F.; Thurston, Roland

2009-01-01

Volcanogenic massive sulfide (VMS) deposits are very significant current and historical resources of Cu-Pb-Zn-Au-Ag, are active exploration targets in several areas of the United States and potentially have significant environmental effects. This new USGS VMS deposit model provides a comprehensive review of deposit occurrence and ore genesis, and fully integrates recent advances in the understanding of active seafloor VMS-forming environments, and integrates consideration of geoenvironmental consequences of mining VMS deposits. Because VMS deposits exhibit a broad range of geological and geochemical characteristics, a suitable classification system is required to incorporate these variations into the mineral deposit model. We classify VMS deposits based on compositional variations in volcanic and sedimentary host rocks. The advantage of the classification method is that it provides a closer linkage between tectonic setting and lithostratigraphic assemblages, and an increased predictive capability during field-based studies.

Decision-case mix model for analyzing variation in cesarean rates.

PubMed

Eldenburg, L; Waller, W S

2001-01-01

This article contributes a decision-case mix model for analyzing variation in c-section rates. Like recent contributions to the literature, the model systematically takes into account the effect of case mix. Going beyond past research, the model highlights differences in physician decision making in response to obstetric factors. Distinguishing the effects of physician decision making and case mix is important in understanding why c-section rates vary and in developing programs to effect change in physician behavior. The model was applied to a sample of deliveries at a hospital where physicians exhibited considerable variation in their c-section rates. Comparing groups with a low versus high rate, the authors' general conclusion is that the difference in physician decision tendencies (to perform a c-section), in response to specific obstetric factors, is at least as important as case mix in explaining variation in c-section rates. The exact effects of decision making versus case mix depend on how the model application defines the obstetric condition of interest and on the weighting of deliveries by their estimated "risk of Cesarean." The general conclusion is supported by an additional analysis that uses the model's elements to predict individual physicians' annual c-section rates.

Correlated evolution of thermal niches and functional physiology in tropical freshwater fishes.

PubMed

Culumber, Zachary W; Tobler, Michael

2018-05-01

The role of ecology in phenotypic and species diversification is widely documented. Nonetheless, numerous nonadaptive processes can shape realized niches and phenotypic variation in natural populations, complicating inferences about adaptive evolution at macroevolutionary scales. We tested for evolved differences in thermal tolerances and their association with the realized thermal niche (including metrics describing diurnal and seasonal patterns of temperature extremes and variability) across a genus of tropical freshwater fishes reared in a standardized environment. There was limited evolution along the thermal niche axis associated with variation in maximum temperature and in upper thermal limits. In contrast, there was considerable diversification along the first major axis of the thermal niche associated with minimum temperatures and in lower thermal limits. Across our adaptive landscape analyses, 70% of species exhibited evidence of divergence in thermal niches. Most importantly, the first two major axes of thermal niche variation were significantly correlated with variation in lower thermal limits. Our results indicate adaptation to divergent thermal niches and adaptive evolution of related functional traits, and highlight the importance of divergence in lower thermal limits for the evolution of tropical biodiversity. © 2018 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2018 European Society For Evolutionary Biology.

A comprehensive profile of DNA copy number variations in a Korean population: identification of copy number invariant regions among Koreans.

PubMed

Jeon, Jae Pil; Shim, Sung Mi; Jung, Jong Sun; Nam, Hye Young; Lee, Hye Jin; Oh, Berm Seok; Kim, Kuchan; Kim, Hyung Lae; Han, Bok Ghee

2009-09-30

To examine copy number variations among the Korean population, we compared individual genomes with the Korean reference genome assembly using the publicly available Korean HapMap SNP 50 k chip data from 90 individuals. Korean individuals exhibited 123 copy number variation regions (CNVRs) covering 27.2 mb, equivalent to 1.0% of the genome in the copy number variation (CNV) analysis using the combined criteria of P value (P<0.01) and standard deviation of copy numbers (SD>or= 0.25) among study subjects. In contrast, when compared to the Affymetrix reference genome assembly from multiple ethnic groups, considerably more CNVRs (n=643) were detected in larger proportions (5.0%) of the genome covering 135.1 mb even by more stringent criteria (P<0.001 and SD>or=0.25), reflecting ethnic diversity of structural variations between Korean and other populations. Some CNVRs were validated by the quantitative multiplex PCR of short fluorescent fragment (QMPSF) method, and then copy number invariant regions were detected among the study subjects. These copy number invariant regions would be used as good internal controls for further CNV studies. Lastly, we demonstrated that the CNV information could stratify even a single ethnic population with a proper reference genome assembly from multiple heterogeneous populations.

Changes in stable isotope composition in Lake Michigan trout ...

EPA Pesticide Factsheets

Researchers have frequently sought to use environmental archives of sediment, peat and glacial ice to try and assess historical trends in atmospheric mercury (Hg) deposition to aquatic ecosystems. While this information is valuable in the context of identifying temporal source trends, these types of assessments cannot account for likely changes in bioavailability of Hg sources that are tied to the formation of methylmercury (MeHg) and accumulation in fish tissues. For this study we propose the use of long-term fish archives and Hg stable isotope determination as an improved means to relate temporal changes in fish Hg levels to varying Hg sources in the Great Lakes. For this study we acquired 180 archived fish composites from Lake Michigan over a 40-year time period (1975 to 2014) from the Great Lakes Fish Monitoring and Surveillance Program, which were analyzed for their total Hg content and Hg isotope abundances. The results reveal that Hg sources to Lake Michigan trout (Salvelinus namaycush) have encountered considerable changes as well as a large shift in the food web trophic position as a result of the introduction of several invasive species, especially the recent invasion of dreissenid mussels. Total Hg concentrations span a large range (1,600 to 150 ng g-1) and exhibit large variations from 1975 to 1985. Ä199Hg signatures similarly exhibit large variation (3.2 to 6.9‰) until 1985, followed by less variation through the end of the data record in 2014.

Impact of chronobiology on neuropathic pain treatment.

PubMed

Gilron, Ian

2016-01-01

Inflammatory pain exhibits circadian rhythmicity. Recently, a distinct diurnal pattern has been described for peripheral neuropathic conditions. This diurnal variation has several implications: advancing understanding of chronobiology may facilitate identification of new and improved treatments; developing pain-contingent strategies that maximize treatment at times of the day associated with highest pain intensity may provide optimal pain relief as well as minimize treatment-related adverse effects (e.g., daytime cognitive dysfunction); and consideration of the impact of chronobiology on pain measurement may lead to improvements in analgesic study design that will maximize assay sensitivity of clinical trials. Recent and ongoing chronobiology studies are thus expected to advance knowledge and treatment of neuropathic pain.

Sources of variation and genetic profile of spontaneous, out-of-season ovulatory activity in the Chios sheep

PubMed Central

Avdi, Melpomeni; Banos, Georgios; Kouttos, Athanasios; Bodin, Loys; Chemineau, Philippe

2003-01-01

Organising the breeding plan of a seasonally breeding species, such as sheep, presents a challenge to farmers and the industry as a whole, since both economical and biological considerations need to be carefully balanced. Understanding the breeding activity of individual animals becomes a prerequisite for a successful breeding program. This study set out to investigate the sources of variation and the genetic profile of the spontaneous, out-of-season ovulatory activity of ewes of the Chios dairy sheep breed in Greece. The definition of the trait was based on blood progesterone levels, measured before exposing the ewes to rams, which marks the onset of the usual breeding season. Data were 707 records, taken over two consecutive years, of 435 ewes kept at the Agricultural Research Station of Chalkidiki in northern Greece. When all available pedigree was included, the total number of animals involved was 1068. On average, 29% of all ewes exhibited spontaneous, out-of-season ovulatory activity, with no substantial variation between the years. Significant sources of systematic variation were the ewe age and live weight, and the month of previous lambing. Older, heavier ewes, that had lambed early the previous autumn, exhibited more frequent activity. Heritability estimates were 0.216 (± 0.084) with a linear and 0.291 with a threshold model. The latter better accounts for the categorical nature of the trait. The linear model repeatability was 0.230 (± 0.095). The results obtained in this study support the notion that spontaneous out-of-season ovulatory activity can be considered in the development of a breeding plan for the Chios sheep breed. PMID:12605851

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.

Geographical variations in seasonal mortality across the United States: A bioclimatological approach

NASA Astrophysics Data System (ADS)

Kalkstein, Adam

2008-10-01

Human mortality exhibits a strong seasonal pattern with deaths in winter far exceeding those in the summer. Surprisingly, this seasonal trend is evident in all major cities across the United States, seemingly independent of climate. While the pattern itself is clear, its magnitude varies considerably across space, and it is not known if there is regional homogeneity among cities. Additionally, the causal mechanisms relating to pattern variability are not clearly understood. The goal of this study is to conduct a comprehensive geographic analysis of seasonal mortality across the United States, to uncover systematic regional differences in such mortality, and to determine what role weather plays in impacting seasonal mortality rates. Unique seasonal mortality curves were created for 28 Metropolitan Statistical Areas across the United States, and the amplitude and timing of mortality peaks were determined. In addition, seasonality was calculated for different demographic groups and causes of death. Meteorological factors were also evaluated as possible causal mechanisms. The findings here indicate that the seasonality of mortality exhibits strong spatial variation with the largest seasonal mortality amplitudes found in the southwestern United States and the smallest in the North, along with South Florida. In addition, there have been changes in the timing of seasonal mortality; the date of maximum mortality is occurring increasingly early in the year. Demographics also play an important role with women, Whites, and the elderly exhibiting the strongest seasonality in mortality. There is a strong connection between respiratory disease and other causes of death, implying a cause-effect relationship. Meteorology also plays an important role in seasonal mortality; variations in the frequency of certain air masses were associated with changes in the timing and amplitude of seasonal mortality. Finally, there were strong intra-regional similarities that exist among the examined cities, implying that environmental factors are more important than social factors in determining seasonal mortality response. This work begins to fill a large gap within the scientific literature concerning the causes, geographic variation, and meteorological influences on seasonal mortality. Additionally, these results will increase the forecasting capabilities of determining when and where winter mortality will reach unusually high levels.

Upper Mantle Texture Patterns In Eastern North America From Seismic Anisotropy And Global Mantle Flow Calculations

NASA Astrophysics Data System (ADS)

Levin, V. L.; Moucha, R.; Yuan, H.

2013-12-01

Global seismic models show gradual and systematic changes in upper mantle seismic properties beneath North America. Faster and thicker lithosphere of the interior thins eastward. Upper mantle rock fabric reflected in observations of seismic anisotropy also varies. Near the coast apparent fast directions of split shear waves are nearly east-west, with considerable scatter. Further inland they are more uniform and align SW-NE, close to the absolute plate motion direction of North America. Mantle convection simulations driven by density inferred from global joint seismic-geodynamic tomography models exhibit complex flow beneath the eastern edge of the North American continent due to the ongoing descent of the Farallon slab deep beneath it (figure 1). Flow predicted beneath the coast is nearly horizontal with a small, though dynamically important, vertical component, while west of the Appalachians it turns downward. Long records of teleseismic observations accumulated at permanent seismic stations HRV, PAL and SSPA (figure 2) are inverted for vertical distribution of anisotropic parameters. We find preference for more than one layer of anisotropy beneath all sites, with significantly different parameters that could reflect either lateral variations in the lithospheric thickness, variations in the asthenospheric flow field, or both. Since we find considerable consistency in directional patterns of P-to-S mode converted waves associated with the lower part of the lithosphere, variations of asthenospheric flow seem to be a more plausible explanation. We explore the links between predicted flow and inferences from seismic data with additional observations of anisotropy and calculations of flow-induced rock fabric.

Morphological and Genetic Analysis of Four Color Morphs of Bean Leaf Beetle.

PubMed

Tiroesele, Bamphitlhi; Skoda, Steven R; Hunt, Thomas E; Lee, Donald J; Ullah, Muhammad Irfan; Molina-Ochoa, Jaime; Foster, John E

2018-03-01

Bean leaf beetle (BLB), Cerotoma trifurcata (Forster; Coleoptera: Chrysomelidae), exhibits considerable color variation but little is known about the underlying genetic structure and gene flow among color phenotypes. Genetic and morphological variation among four color phenotypes-green with spots (G+S), green without spots (G-S), red with spots (R+S) and red without spots (R-S)-were analyzed using amplified fragment length polymorphisms (AFLP) and morphometrics, respectively. AFLP generated 175 markers that showed ≥80% polymorphism. Analysis of molecular variance (AMOVA) indicated that genetic variation was greatest within phenotypes (82.6-84.0%); gene flow among the four phenotypes was relatively high (Nm = 3.82). The dendrogram and STRUCTURE analysis indicated some population divergence of G-S from the other phenotypes. Morphological parameters were similar among phenotypes except that R+S showed significant differences in weight and body-length. Canonical variables 1 and 2, based on average morphometric characters, accounted for 98% of the total variation; some divergence was indicated between G+S and R+S from each other and from the G-S/R-S BLB color morphs. The pattern of genetic variation indicated potential divergence of G-S and G+S from each other and from R-S and R+S. Although these results indicate that the four different color morphs are not genetically or reproductively isolated, there is some genetic differentiation/structure and morphological dissimilarity suggesting weak/incomplete isolation.

Practical Considerations for Using Constant Force Springs in Space-Based Mechanisms

NASA Technical Reports Server (NTRS)

Williams, R. Brett; Fisher, Charles D.; Gallon, John C.

2013-01-01

Mechanical springs are a common element in mechanism from all walks of life; cars, watches, appliances, and many others. These springs generally exhibit a linear relationship between force and deflection. In small mechanisms, deflections are small so the variation in spring force between one position and another are generally small and do not influence the design or functionality of the device. However, as the spacecraft industry drives towards larger, deployable satellites, the distances a spring or springs must function over can become considerable so much so that the structural integrity of the device may be impacted. As such, an increasingly common mechanism element is the constant force spring- one that provides a constant force regardless of deflection. These elements are commonly in the conceptual design phase to deal with system-level large deflections, but in the detailed design or integration test phase they can pose significant implementation issues. This article addresses some of the detailed issues in order for these constant force springs to be properly designed into space systems.

Stratospheric ozone as viewed from the Chappuis band. [long term pollution monitoring

NASA Technical Reports Server (NTRS)

Angione, R. J.; Medeiros, E. J.; Roosen, R. G.

1976-01-01

Total stratospheric ozone values above high-altitude stations in southern California from 1912 to 1950 and northern Chile from 1918 to 1948 are determined using data obtained by the Smithsonian Astrophysical Observatory, including transmission measurements made in the Chappuis band (0.5 to 0.7 micron). The results show that at both sites, total ozone amounts commonly exhibit variations of as much as 20% to 30% on time scales ranging from months to decades. Consideration of the amount of incident solar energy absorbed by the Chappuis band suggests that ozone acts as a shutter on the incoming solar radiation and provides a trigger mechanism between solar activity and climatic change.

Genomic signatures among Oncorhynchus nerka ecotypes to inform conservation and management of endangered Sockeye Salmon.

PubMed

Nichols, Krista M; Kozfkay, Christine C; Narum, Shawn R

2016-12-01

Conservation of life history variation is an important consideration for many species with trade-offs in migratory characteristics. Many salmonid species exhibit both resident and migratory strategies that capitalize on benefits in freshwater and marine environments. In this study, we investigated genomic signatures for migratory life history in collections of resident and anadromous Oncorhynchus nerka (Kokanee and Sockeye Salmon, respectively) from two lake systems, using ~2,600 SNPs from restriction-site-associated DNA sequencing (RAD-seq). Differing demographic histories were evident in the two systems where one pair was significantly differentiated (Redfish Lake, F ST  = 0.091 [95% confidence interval: 0.087 to 0.095]) but the other pair was not (Alturas Lake, F ST  = -0.007 [-0.008 to -0.006]). Outlier and association analyses identified several candidate markers in each population pair, but there was limited evidence for parallel signatures of genomic variation associated with migration. Despite lack of evidence for consistent markers associated with migratory life history in this species, candidate markers were mapped to functional genes and provide evidence for adaptive genetic variation within each lake system. Life history variation has been maintained in these nearly extirpated populations of O. nerka, and conservation efforts to preserve this diversity are important for long-term resiliency of this species.

Radiation dosimetry properties of smartphone CMOS sensors.

PubMed

Van Hoey, Olivier; Salavrakos, Alexia; Marques, Antonio; Nagao, Alexandre; Willems, Ruben; Vanhavere, Filip; Cauwels, Vanessa; Nascimento, Luana F

2016-03-01

During the past years, several smartphone applications have been developed for radiation detection. These applications measure radiation using the smartphone camera complementary metal-oxide-semiconductor sensor. They are potentially useful for data collection and personal dose assessment in case of a radiological incident. However, it is important to assess these applications. Six applications were tested by means of irradiations with calibrated X-ray and gamma sources. It was shown that the measurement stabilises only after at least 10-25 min. All applications exhibited a flat dose rate response in the studied ambient dose equivalent range from 2 to 1000 μSv h(-1). Most applications significantly over- or underestimate the dose rate or are not calibrated in terms of dose rate. A considerable energy dependence was observed below 100 keV but not for the higher energy range more relevant for incident scenarios. Photon impact angle variation gave a measured signal variation of only about 10 %. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Assessing the spatiotemporal dynamic of global grassland carbon use efficiency in response to climate change from 2000 to 2013

NASA Astrophysics Data System (ADS)

Yang, Yue; Wang, Zhaoqi; Li, Jianlong; Gang, Chencheng; Zhang, Yanzhen; Odeh, Inakwu; Qi, Jiaguo

2017-05-01

The carbon use efficiency (CUE) of grassland, a ratio of net primary production (NPP) to gross primary productivity (GPP), is an important index representing the capacity of plants to transfer carbon from the atmosphere to terrestrial biomass. In this study, we used the Moderate Resolution Imaging Spectroradiometer (MODIS) data to calculate the global grassland CUE, and explore the spatiotemporal dynamic of global grassland CUE from 2000 to 2013 to discuss the response to climate variations. The results showed that the average annual CUE of different grassland types follows an order of: open shrublands > non-woody grasslands > closed shrublands > woody savannas > savannas. The higher grassland CUE mainly occurred in the regions with cold and dry climate. By contrast, the regions with the lower grassland CUE were mostly in warm and wet environments. Moreover, the CUE exhibited a globally positive correlation with precipitation and a negative correlation with temperature. Therefore, the grassland CUE has considerable spatial variation associated with grassland type, geographical location and climate change.

Distribution and solid-phase speciation of toxic heavy metals of bed sediments of Bharali tributary of Brahmaputra River.

PubMed

Hoque, Raza Rafiqul; Goswami, K G; Kusre, B C; Sarma, K P

2011-06-01

Heavy metal (Fe, Mn, Zn, Cu, Ni, Pb, and Cd) concentrations and their chemical speciations were investigated for the first time in bed sediments of Bharali River, a major tributary of the Brahmaputra River of the Eastern Himalayas. Levels of Fe, Mn, Pb, and Cd in the bed sediments were much below the average Indian rivers; however, Cu and Zn exhibit levels on the higher side. Enrichment factors (EF) of all metals was greater than 1 and a higher trend of EF was seen in the abandoned channel for most metals. Pb showed maximum EF of 32 at site near an urban center. The geoaccumulation indices indicate that Bharali river is moderately polluted. The metals speciations, done by a sequential extraction regime, show that Cd, Cu, and Pb exhibit considerable presence in the exchangeable and carbonate fraction, thereby showing higher mobility and bioavailability. On the other hand, Ni, Mn, and Fe exhibit greater presence in the residual fraction and Zn was dominant in the Fe-Mn oxide phase. Inter-species correlations at three sites did not show similar trends for metal pairs indicating potential variations in the contributing sources.

Developmental constraints on behavioural flexibility.

PubMed

Holekamp, Kay E; Swanson, Eli M; Van Meter, Page E

2013-05-19

We suggest that variation in mammalian behavioural flexibility not accounted for by current socioecological models may be explained in part by developmental constraints. From our own work, we provide examples of constraints affecting variation in behavioural flexibility, not only among individuals, but also among species and higher taxonomic units. We first implicate organizational maternal effects of androgens in shaping individual differences in aggressive behaviour emitted by female spotted hyaenas throughout the lifespan. We then compare carnivores and primates with respect to their locomotor and craniofacial adaptations. We inquire whether antagonistic selection pressures on the skull might impose differential functional constraints on evolvability of skulls and brains in these two orders, thus ultimately affecting behavioural flexibility in each group. We suggest that, even when carnivores and primates would theoretically benefit from the same adaptations with respect to behavioural flexibility, carnivores may nevertheless exhibit less behavioural flexibility than primates because of constraints imposed by past adaptations in the morphology of the limbs and skull. Phylogenetic analysis consistent with this idea suggests greater evolutionary lability in relative brain size within families of primates than carnivores. Thus, consideration of developmental constraints may help elucidate variation in mammalian behavioural flexibility.

Magnetic field and radial velocities of the star β CrB

NASA Astrophysics Data System (ADS)

Han, Inwoo; Valyavin, G.; Galazutdinov, G.; Plachinda, S.; Butkovskaya, V.; Lee, B. C.; Kim, Kang-Min; Jeong, Gwanghui; Romanyuk, I.; Burlakova, T.

2018-06-01

We present the results of long term high-resolution spectral and spectro-polarimetric observations of the classic spectroscopic binary star β Coronae Borealis, which is also well known for its chemical peculiarity and strong magnetic field. One of the main objectives of these observations was to check some suggestions of the presence of a third low-mass component in the system. Analysing our own radial velocity measurements of β Coronae Borealis obtained between 2004 and 2013 together with other RV and astrometric data taken from literature, we have considerably improved the orbital elements of the star. Using residual RVs obtained after subtracting the orbit from the observed RV, we detected a significant periodic signal consistent with the well known 18.4868 day rotation/magnetic period of the star. The shape of the residual RVs folded with the rotation period exhibits a bimodal structure. In order to clarify the origin of the residual RV variation, we model the RV variation due to rotational modulation Zeeman patterns in the spectral lines of β Coronae Borealis spectra. The results of this analysis and the investigation of chemical inhomogeneities in the spectra of β Coronae Borealis convincingly support the "magnetic" nature of the observed radial velocity variations.

The effect of the solar rotational irradiance variation on the middle and upper atmosphere calculated by a three-dimensional chemistry-climate model

NASA Astrophysics Data System (ADS)

Gruzdev, A. N.; Schmidt, H.; Brasseur, G. P.

2009-01-01

This paper analyzes the effects of the solar rotational (27-day) irradiance variations on the chemical composition and temperature of the stratosphere, mesosphere and lower thermosphere as simulated by the three-dimensional chemistry-climate model HAMMONIA. Different methods are used to analyze the model results, including high resolution spectral and cross-spectral techniques. To force the simulations, an idealized irradiance variation with a constant period of 27 days (apparent solar rotation period) and with constant amplitude is used. While the calculated thermal and chemical responses are very distinct and permanent in the upper atmosphere, the responses in the stratosphere and mesosphere vary considerably in time despite the constant forcing. The responses produced by the model exhibit a non-linear behavior: in general, the response sensitivities (not amplitudes) decrease with increasing amplitude of the forcing. In the extratropics the responses are, in general, seasonally dependent with frequently stronger sensitivities in winter than in summer. Amplitude and phase lag of the ozone response in the tropical stratosphere and lower mesosphere are in satisfactory agreement with available observations. The agreement between the calculated and observed temperature response is generally worse than in the case of ozone.

Clay mineralogy, strontium and neodymium isotope ratios in the sediments of two High Arctic catchments (Svalbard)

NASA Astrophysics Data System (ADS)

Hindshaw, Ruth S.; Tosca, Nicholas J.; Piotrowski, Alexander M.; Tipper, Edward T.

2018-03-01

The identification of sediment sources to the ocean is a prerequisite to using marine sediment cores to extract information on past climate and ocean circulation. Sr and Nd isotopes are classical tools with which to trace source provenance. Despite considerable interest in the Arctic Ocean, the circum-Arctic source regions are poorly characterised in terms of their Sr and Nd isotopic compositions. In this study we present Sr and Nd isotope data from the Paleogene Central Basin sediments of Svalbard, including the first published data of stream suspended sediments from Svalbard. The stream suspended sediments exhibit considerable isotopic variation (ɛNd = -20.6 to -13.4; 87Sr / 86Sr = 0.73421 to 0.74704) which can be related to the depositional history of the sedimentary formations from which they are derived. In combination with analysis of the clay mineralogy of catchment rocks and sediments, we suggest that the Central Basin sedimentary rocks were derived from two sources. One source is Proterozoic sediments derived from Greenlandic basement rocks which are rich in illite and have high 87Sr / 86Sr and low ɛNd values. The second source is Carboniferous to Jurassic sediments derived from Siberian basalts which are rich in smectite and have low 87Sr / 86Sr and high ɛNd values. Due to a change in depositional conditions throughout the Paleogene (from deep sea to continental) the relative proportions of these two sources vary in the Central Basin formations. The modern stream suspended sediment isotopic composition is then controlled by modern processes, in particular glaciation, which determines the present-day exposure of the formations and therefore the relative contribution of each formation to the stream suspended sediment load. This study demonstrates that the Nd isotopic composition of stream suspended sediments exhibits seasonal variation, which likely mirrors longer-term hydrological changes, with implications for source provenance studies based on fixed end-members through time.

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.;

Extensive Natural Intraspecific Variation in Stoichiometric (C:N:P) Composition in Two Terrestrial Insect Species

PubMed Central

Bertram, S. M.; Bowen, M.; Kyle, M.; Schade, J. D.

2008-01-01

Heterotrophic organisms must obtain essential elements in sufficient quantities from their food. Because plants naturally exhibit extensive variation in their elemental content, it is important to quantify the within-species stoichiometric variation of consumers. If extensive stoichiometric variation exists, it may help explain consumer variation in life-history strategy and fitness. To date, however, research on stoichiometric variation has focused on interspecific differences and assumed minimal intraspecific differences. Here this assumption is tested. Natural variation is quantified in body stoichiometry of two terrestrial insects: the generalist field cricket, Gryllus texensis Cade and Otte (Orthoptera: Gryllidae) and a specialist curculionid weevil, Sabinia setosa (Le Conte) (Coleoptera: Curculionidae). Both species exhibited extensive intraspecific stoichiometric variation. Cricket body nitrogen content ranged from 8–12% and there was a four-fold difference in body phosphorus content, ranging from 0.32–1.27%. Body size explained half this stoichiometric variation, with larger individuals containing less nitrogen and phosphorus. Weevils exhibited an almost three-fold difference in body phosphorus content, ranging from 0.38–0.97%. Overall, the variation observed within each of these species is comparable to the variation previously observed across almost all terrestrial insect species. PMID:20298114

The 57Fe Mössbauer parameters of pyrite and marcasite with different provenances

USGS Publications Warehouse

Evans, B.J.; Johnson, R.G.; Senftle, F.E.; Cecil, C.B.; Dulong, F.

1982-01-01

The Mössbauer parameters of pyrite and marcasite exhibit appreciable variations, which bear no simple relationship to the geological environment in which they occur but appear to be selectively influenced by impurities, especially arsenic, in the pyrite lattice. Quantitative and qualitative determinations of pyrite/marcasite mechanical mixtures are straightforward at 298 K and 77 K but do require least-squares computer fittings and are limited to accuracies ranging from ±5 to ±15 per cent by uncertainties in the parameter values of the pure phases. The methodology and results of this investigation are directly applicable to coals for which the presence and relative amounts of pyrite and marcasite could be of considerable genetic significance.

Influence of climate on the survivorship of neonatal red pandas in captivity.

PubMed

Princée, Frank P G; Glatston, Angela R

2016-01-01

Red pandas, Ailurus fulgens, are popular exhibit animals in zoos. It is clear from data in the global studbook that there is considerable variation in their breeding success in different zoos. Population managers have long suspected that environmental temperature plays a key role in these differences. It is generally thought that this species, which is so well adapted to life in the cold damp climate of the mid-altitude forests of the Himalayas, has a problem coping with warmer climates. However, this hypothesis has not been tested until now. Using data extracted from the global studbook, we have demonstrated that climate at the location of birth has a clear impact on the survival of infant red pandas. © 2016 Wiley Periodicals, Inc.

Studies of silicon pn junction solar cells

NASA Technical Reports Server (NTRS)

Lindholm, F. A.; Neugroschel, A.

1977-01-01

Modifications of the basic Shockley equations that result from the random and nonrandom spatial variations of the chemical composition of a semiconductor were developed. These modifications underlie the existence of the extensive emitter recombination current that limits the voltage over the open circuit of solar cells. The measurement of parameters, series resistance and the base diffusion length is discussed. Two methods are presented for establishing the energy bandgap narrowing in the heavily-doped emitter region. Corrections that can be important in the application of one of these methods to small test cells are examined. Oxide-charge-induced high-low-junction emitter (OCI-HLE) test cells which exhibit considerably higher voltage over the open circuit than was previously seen in n-on-p solar cells are described.

The latitudinal gradient of the NO peak density

NASA Technical Reports Server (NTRS)

Fesen, C. G.; Rusch, D. W.; Gerard, J.-C.

1990-01-01

Results are presented from SME observations of the latitudinal gradients of peak NO densities at about 110-km altitude during the solstice and equinox periods from 1982 through 1985. It is shown that the response of the peak NO densities to the declining level of solar activity varies with latitude, with the polar regions exhibiting low sensitivity and the low-latitude regions responding strongly. The SME data also revealed marked asymmetries in the latitudinal structure of the two hemispheres for each season and considerable day-to-day variations in the NO densities. The solar cycle minimum data for June were simulated using a two-dimensional model; results of sensitivity studies performed with varied quenching rate and eddy diffusion coefficient are presented.

The Costs of Delivering Integrated HIV and Sexual Reproductive Health Services in Limited Resource Settings.

PubMed

Obure, Carol Dayo; Sweeney, Sedona; Darsamo, Vanessa; Michaels-Igbokwe, Christine; Guinness, Lorna; Terris-Prestholt, Fern; Muketo, Esther; Nhlabatsi, Zelda; Warren, Charlotte E; Mayhew, Susannah; Watts, Charlotte; Vassall, Anna

2015-01-01

To present evidence on the total costs and unit costs of delivering six integrated sexual reproductive health and HIV services in a high and medium HIV prevalence setting, in order to support policy makers and planners scaling up these essential services. A retrospective facility based costing study conducted in 40 non-government organization and public health facilities in Kenya and Swaziland. Economic and financial costs were collected retrospectively for the year 2010/11, from each study site with an aim to estimate the cost per visit of six integrated HIV and SRH services. A full cost analysis using a combination of bottom-up and step-down costing methods was conducted from the health provider's perspective. The main unit of analysis is the economic unit cost per visit for each service. Costs are converted to 2013 International dollars. The mean cost per visit for the HIV/SRH services ranged from $Int 14.23 (PNC visit) to $Int 74.21 (HIV treatment visit). We found considerable variation in the unit costs per visit across settings with family planning services exhibiting the least variation ($Int 6.71-52.24) and STI treatment and HIV treatment visits exhibiting the highest variation in unit cost ranging from ($Int 5.44-281.85) and ($Int 0.83-314.95), respectively. Unit costs of visits were driven by fixed costs while variability in visit costs across facilities was explained mainly by technology used and service maturity. For all services, variability in unit costs and cost components suggest that potential exists to reduce costs through better use of both human and capital resources, despite the high proportion of expenditure on drugs and medical supplies. Further work is required to explore the key drivers of efficiency and interventions that may facilitate efficiency improvements.

The Role of Copy Number Variation in Susceptibility to Amyotrophic Lateral Sclerosis: Genome-Wide Association Study and Comparison with Published Loci

PubMed Central

Wain, Louise V.; Pedroso, Inti; Landers, John E.; Breen, Gerome; Shaw, Christopher E.; Leigh, P. Nigel; Brown, Robert H.

2009-01-01

Background The genetic contribution to sporadic amyotrophic lateral sclerosis (ALS) has not been fully elucidated. There are increasing efforts to characterise the role of copy number variants (CNVs) in human diseases; two previous studies concluded that CNVs may influence risk of sporadic ALS, with multiple rare CNVs more important than common CNVs. A little-explored issue surrounding genome-wide CNV association studies is that of post-calling filtering and merging of raw CNV calls. We undertook simulations to define filter thresholds and considered optimal ways of merging overlapping CNV calls for association testing, taking into consideration possibly overlapping or nested, but distinct, CNVs and boundary estimation uncertainty. Methodology and Principal Findings In this study we screened Illumina 300K SNP genotyping data from 730 ALS cases and 789 controls for copy number variation. Following quality control filters using thresholds defined by simulation, a total of 11321 CNV calls were made across 575 cases and 621 controls. Using region-based and gene-based association analyses, we identified several loci showing nominally significant association. However, the choice of criteria for combining calls for association testing has an impact on the ranking of the results by their significance. Several loci which were previously reported as being associated with ALS were identified here. However, of another 15 genes previously reported as exhibiting ALS-specific copy number variation, only four exhibited copy number variation in this study. Potentially interesting novel loci, including EEF1D, a translation elongation factor involved in the delivery of aminoacyl tRNAs to the ribosome (a process which has previously been implicated in genetic studies of spinal muscular atrophy) were identified but must be treated with caution due to concerns surrounding genomic location and platform suitability. Conclusions and Significance Interpretation of CNV association findings must take into account the effects of filtering and combining CNV calls when based on early genome-wide genotyping platforms and modest study sizes. PMID:19997636

Migratory Patterns of Wild Chinook Salmon Oncorhynchus tshawytscha Returning to a Large, Free-Flowing River Basin

PubMed Central

Eiler, John H.; Evans, Allison N.; Schreck, Carl B.

2015-01-01

Upriver movements were determined for Chinook salmon Oncorhynchus tshawytscha returning to the Yukon River, a large, virtually pristine river basin. These returns have declined dramatically since the late 1990s, and information is needed to better manage the run and facilitate conservation efforts. A total of 2,860 fish were radio tagged during 2002–2004. Most (97.5%) of the fish tracked upriver to spawning areas displayed continual upriver movements and strong fidelity to the terminal tributaries entered. Movement rates were substantially slower for fish spawning in lower river tributaries (28–40 km d-1) compared to upper basin stocks (52–62 km d-1). Three distinct migratory patterns were observed, including a gradual decline, pronounced decline, and substantial increase in movement rate as the fish moved upriver. Stocks destined for the same region exhibited similar migratory patterns. Individual fish within a stock showed substantial variation, but tended to reflect the regional pattern. Differences between consistently faster and slower fish explained 74% of the within-stock variation, whereas relative shifts in sequential movement rates between “hares” (faster fish becoming slower) and “tortoises” (slow but steady fish) explained 22% of the variation. Pulses of fish moving upriver were not cohesive. Fish tagged over a 4-day period took 16 days to pass a site 872 km upriver. Movement rates were substantially faster and the percentage of atypical movements considerably less than reported in more southerly drainages, but may reflect the pristine conditions within the Yukon River, wild origins of the fish, and discrete run timing of the returns. Movement data can provide numerous insights into the status and management of salmon returns, particularly in large river drainages with widely scattered fisheries where management actions in the lower river potentially impact harvests and escapement farther upstream. However, the substantial variation exhibited among individual fish within a stock can complicate these efforts. PMID:25919286

Migratory Patterns of Chinook Salmon Oncorhynchus tshawytscha Returning to a Large, Free-flowing River Basin

USGS Publications Warehouse

Eiler, John H.; Evans, Allison N.; Schreck, Carl B.

2015-01-01

Upriver movements were determined for Chinook salmon Oncorhynchus tshawytscha returning to the Yukon River, a large, virtually pristine river basin. These returns have declined dramatically since the late 1990s, and information is needed to better manage the run and facilitate conservation efforts. A total of 2,860 fish were radio tagged during 2002–2004. Most (97.5%) of the fish tracked upriver to spawning areas displayed continual upriver movements and strong fidelity to the terminal tributaries entered. Movement rates were substantially slower for fish spawning in lower river tributaries (28–40 km d-1) compared to upper basin stocks (52–62 km d-1). Three distinct migratory patterns were observed, including a gradual decline, pronounced decline, and substantial increase in movement rate as the fish moved upriver. Stocks destined for the same region exhibited similar migratory patterns. Individual fish within a stock showed substantial variation, but tended to reflect the regional pattern. Differences between consistently faster and slower fish explained 74% of the within-stock variation, whereas relative shifts in sequential movement rates between “hares” (faster fish becoming slower) and “tortoises” (slow but steady fish) explained 22% of the variation. Pulses of fish moving upriver were not cohesive. Fish tagged over a 4-day period took 16 days to pass a site 872 km upriver. Movement rates were substantially faster and the percentage of atypical movements considerably less than reported in more southerly drainages, but may reflect the pristine conditions within the Yukon River, wild origins of the fish, and discrete run timing of the returns. Movement data can provide numerous insights into the status and management of salmon returns, particularly in large river drainages with widely scattered fisheries where management actions in the lower river potentially impact harvests and escapement farther upstream. However, the substantial variation exhibited among individual fish within a stock can complicate these efforts.

Population characteristics of DNA fingerprints in humpback whales (Megaptera novaeangliae).

PubMed

Baker, C S; Gilbert, D A; Weinrich, M T; Lambertsen, R; Calambokidis, J; McArdle, B; Chambers, G K; O'Brien, S J

1993-01-01

Humpback whales exhibit a remarkable social organization that is characterized by seasonal long-distance migration (> 10,000 km/year) between summer feeding grounds in high latitudes and winter calving and breeding grounds in tropical or near-tropical waters. All populations are currently considered endangered as a result of intensive commercial exploitation during the last 200 years. Using three hypervariable minisatellite DNA probes (33.15, 3'HVR, and M13) originally developed for studies of human genetic variation, we examined genetic variation within and among three regional subpopulations of humpback whales from the North Pacific and one from the North Atlantic oceans. Analysis of DNA extracted from skin tissues collected by biopsy darting from free-ranging whales revealed considerable variation in each subpopulation. The extent of this variation argues against a recent history of inbreeding among humpback whales as a result of nineteenth- and twentieth-century hunting. A canonical variate analysis suggested a relationship between scaled genetic distance, based on similarities of DNA fingerprints, and geographic distance (i.e., longitude of regional subpopulation). Significant categorical differences were found between the two oceanic populations using a multivariate analysis of variance (MANOVA) with a modification of the Mantel nonparametric permutation test. The relationship between DNA fingerprint similarities and geographic distance suggests that nuclear gene flow between regional subpopulations within the North Pacific is restricted by relatively low rates of migratory interchange between breeding grounds or assortative mating on common wintering grounds.

The fall and rise of the Icelandic Arctic fox (Vulpes lagopus): a 50-year demographic study on a non-cyclic Arctic fox population.

PubMed

Unnsteinsdottir, E R; Hersteinsson, P; Pálsson, S; Angerbjörn, A

2016-08-01

In territorial species, observed density dependence is often manifest in lowered reproductive output at high population density where individuals have fewer resources or are forced to inhabit low-quality territories. The Arctic fox (Vulpes lagopus) in Iceland is territorial throughout the year and feeds mostly on birds, since lemmings are absent from the country. Thus, the population does not exhibit short-term population cycles that are evident in most of the species' geographical range. The population has, however, gone through a major long-term fluctuation in population size. Because of the stability in hunting effort and reliable hunting records since 1958, the total number of adult foxes killed annually can be used as an index of population size (N t ). An index of carrying capacity (K) from population growth data for five separate time blocks during 1958-2007 revealed considerable variation in K and allowed a novel definition of population density in terms of K, or N t /K. Correlation analysis suggested that the reproductive rate was largely determined by the proportion of territorial foxes in the population. Variation in litter size and cub mortality was, on the other hand, related to climatic variation. Thus, Arctic foxes in Iceland engage in typical contest competition but can adapt their territory sizes in response to both temporal and spatial variation in carrying capacity, resulting in surprisingly little variation in litter size.

Analysis of the Nonlinear Trends and Non-Stationary Oscillations of Regional Precipitation in Xinjiang, Northwestern China, Using Ensemble Empirical Mode Decomposition

PubMed Central

Guo, Bin; Chen, Zhongsheng; Guo, Jinyun; Liu, Feng; Chen, Chuanfa; Liu, Kangli

2016-01-01

Changes in precipitation could have crucial influences on the regional water resources in arid regions such as Xinjiang. It is necessary to understand the intrinsic multi-scale variations of precipitation in different parts of Xinjiang in the context of climate change. In this study, based on precipitation data from 53 meteorological stations in Xinjiang during 1960–2012, we investigated the intrinsic multi-scale characteristics of precipitation variability using an adaptive method named ensemble empirical mode decomposition (EEMD). Obvious non-linear upward trends in precipitation were found in the north, south, east and the entire Xinjiang. Changes in precipitation in Xinjiang exhibited significant inter-annual scale (quasi-2 and quasi-6 years) and inter-decadal scale (quasi-12 and quasi-23 years). Moreover, the 2–3-year quasi-periodic fluctuation was dominant in regional precipitation and the inter-annual variation had a considerable effect on the regional-scale precipitation variation in Xinjiang. We also found that there were distinctive spatial differences in variation trends and turning points of precipitation in Xinjiang. The results of this study indicated that compared to traditional decomposition methods, the EEMD method, without using any a priori determined basis functions, could effectively extract the reliable multi-scale fluctuations and reveal the intrinsic oscillation properties of climate elements. PMID:27007388

Genomic Analysis of Phylotype I Strain EP1 Reveals Substantial Divergence from Other Strains in the Ralstonia solanacearum Species Complex

PubMed Central

Li, Peng; Wang, Dechen; Yan, Jinli; Zhou, Jianuan; Deng, Yinyue; Jiang, Zide; Cao, Bihao; He, Zifu; Zhang, Lianhui

2016-01-01

Ralstonia solanacearum species complex is a devastating group of phytopathogens with an unusually wide host range and broad geographical distribution. R. solanacearum isolates may differ considerably in various properties including host range and pathogenicity, but the underlying genetic bases remain vague. Here, we conducted the genome sequencing of strain EP1 isolated from Guangdong Province of China, which belongs to phylotype I and is highly virulent to a range of solanaceous crops. Its complete genome contains a 3.95-Mb chromosome and a 2.05-Mb mega-plasmid, which is considerably bigger than reported genomes of other R. solanacearum strains. Both the chromosome and the mega-plasmid have essential house-keeping genes and many virulence genes. Comparative analysis of strain EP1 with other 3 phylotype I and 3 phylotype II, III, IV strains unveiled substantial genome rearrangements, insertions and deletions. Genome sequences are relatively conserved among the 4 phylotype I strains, but more divergent among strains of different phylotypes. Moreover, the strains exhibited considerable variations in their key virulence genes, including those encoding secretion systems and type III effectors. Our results provide valuable information for further elucidation of the genetic basis of diversified virulences and host range of R. solanacearum species. PMID:27833603

Population genetic structure of traditional populations in the Peruvian Central Andes and implications for South American population history.

PubMed

Cabana, Graciela S; Lewis, Cecil M; Tito, Raúl Y; Covey, R Alan; Cáceres, Angela M; Cruz, Augusto F De La; Durand, Diana; Housman, Genevieve; Hulsey, Brannon I; Iannacone, Gian Carlo; López, Paul W; Martínez, Rolando; Medina, Ángel; Dávila, Olimpio Ortega; Pinto, Karla Paloma Osorio; Santillán, Susan I Polo; Domínguez, Percy Rojas; Rubel, Meagan; Smith, Heather F; Smith, Silvia E; Massa, Verónica Rubín de Celis; Lizárraga, Beatriz; Stone, Anne C

2014-01-01

Molecular-based characterizations of Andean peoples are traditionally conducted in the service of elucidating continent-level evolutionary processes in South America. Consequently, genetic variation among "western" Andean populations is often represented in relation to variation among "eastern" Amazon and Orinoco River Basin populations. This west-east contrast in patterns of population genetic variation is typically attributed to large-scale phenomena, such as dual founder colonization events or differing long-term microevolutionary histories. However, alternative explanations that consider the nature and causes of population genetic diversity within the Andean region remain underexplored. Here we examine population genetic diversity in the Peruvian Central Andes using data from the mtDNA first hypervariable region and Y-chromosome short tandem repeats among 17 newly sampled populations and 15 published samples. Using this geographically comprehensive data set, we first reassessed the currently accepted pattern of western versus eastern population genetic structure, which our results ultimately reject: mtDNA population diversities were lower, rather than higher, within Andean versus eastern populations, and only highland Y-chromosomes exhibited significantly higher within-population diversities compared with eastern groups. Multiple populations, including several highland samples, exhibited low genetic diversities for both genetic systems. Second, we explored whether the implementation of Inca state and Spanish colonial policies starting at about ad 1400 could have substantially restructured population genetic variation and consequently constitute a primary explanation for the extant pattern of population diversity in the Peruvian Central Andes. Our results suggest that Peruvian Central Andean population structure cannot be parsimoniously explained as the sole outcome of combined Inca and Spanish policies on the region's population demography: highland populations differed from coastal and lowland populations in mtDNA genetic structure only; highland groups also showed strong evidence of female-biased gene flow and/or effective sizes relative to other Peruvian ecozones. Taken together, these findings indicate that population genetic structure in the Peruvian Central Andes is considerably more complex than previously reported and that characterizations of and explanations for genetic variation may be best pursued within more localized regions and defined time periods.

Simultaneous Profiling of Lysoglycerophospholipids in Rice (Oryza sativa L.) Using Direct Infusion-Tandem Mass Spectrometry with Multiple Reaction Monitoring.

PubMed

Lim, Dong Kyu; Mo, Changyeun; Long, Nguyen Phuoc; Kim, Giyoung; Kwon, Sung Won

2017-03-29

White rice is the final product after the hull and bran layers have been removed during the milling process. Although lysoglycerophospholipids (lysoGPLs) only occupy a small proportion in white rice, they are essential for evaluating rice authenticity and quality. In this study, we developed a high-throughput and targeted lipidomics approach that involved direct infusion-tandem mass spectrometry with multiple reaction monitoring to simultaneously profile lysoGPLs in white rice. The method is capable of characterizing 17 lysoGPLs within 1 min. In addition, unsupervised and supervised analyses exhibited a considerably large diversity of lysoGPL concentrations in white rice from different origins. In particular, a classification model was built using identified lysoGPLs that can differentiate white rice from Korea, China, and Japan. Among the discriminatory lysoGPLs, for the lysoPE(16:0) and lysoPE(18:2) compositions, there were relatively small within-group variations, and they were considerably different among the three countries. In conclusion, our proposed method provides a rapid, high-throughput, and comprehensive format for profiling lysoGPLs in rice samples.

Predicting the limits to tree height using statistical regressions of leaf traits.

PubMed

Burgess, Stephen S O; Dawson, Todd E

2007-01-01

Leaf morphology and physiological functioning demonstrate considerable plasticity within tree crowns, with various leaf traits often exhibiting pronounced vertical gradients in very tall trees. It has been proposed that the trajectory of these gradients, as determined by regression methods, could be used in conjunction with theoretical biophysical limits to estimate the maximum height to which trees can grow. Here, we examined this approach using published and new experimental data from tall conifer and angiosperm species. We showed that height predictions were sensitive to tree-to-tree variation in the shape of the regression and to the biophysical endpoints selected. We examined the suitability of proposed end-points and their theoretical validity. We also noted that site and environment influenced height predictions considerably. Use of leaf mass per unit area or leaf water potential coupled with vulnerability of twigs to cavitation poses a number of difficulties for predicting tree height. Photosynthetic rate and carbon isotope discrimination show more promise, but in the second case, the complex relationship between light, water availability, photosynthetic capacity and internal conductance to CO(2) must first be characterized.

The compression–error trade-off for large gridded data sets

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

Silver, Jeremy D.; Zender, Charles S.

The netCDF-4 format is widely used for large gridded scientific data sets and includes several compression methods: lossy linear scaling and the non-lossy deflate and shuffle algorithms. Many multidimensional geoscientific data sets exhibit considerable variation over one or several spatial dimensions (e.g., vertically) with less variation in the remaining dimensions (e.g., horizontally). On such data sets, linear scaling with a single pair of scale and offset parameters often entails considerable loss of precision. We introduce an alternative compression method called "layer-packing" that simultaneously exploits lossy linear scaling and lossless compression. Layer-packing stores arrays (instead of a scalar pair) of scalemore » and offset parameters. An implementation of this method is compared with lossless compression, storing data at fixed relative precision (bit-grooming) and scalar linear packing in terms of compression ratio, accuracy and speed. When viewed as a trade-off between compression and error, layer-packing yields similar results to bit-grooming (storing between 3 and 4 significant figures). Bit-grooming and layer-packing offer significantly better control of precision than scalar linear packing. Relative performance, in terms of compression and errors, of bit-groomed and layer-packed data were strongly predicted by the entropy of the exponent array, and lossless compression was well predicted by entropy of the original data array. Layer-packed data files must be "unpacked" to be readily usable. The compression and precision characteristics make layer-packing a competitive archive format for many scientific data sets.« less

The compression–error trade-off for large gridded data sets

DOE PAGES

Silver, Jeremy D.; Zender, Charles S.

2017-01-27

The netCDF-4 format is widely used for large gridded scientific data sets and includes several compression methods: lossy linear scaling and the non-lossy deflate and shuffle algorithms. Many multidimensional geoscientific data sets exhibit considerable variation over one or several spatial dimensions (e.g., vertically) with less variation in the remaining dimensions (e.g., horizontally). On such data sets, linear scaling with a single pair of scale and offset parameters often entails considerable loss of precision. We introduce an alternative compression method called "layer-packing" that simultaneously exploits lossy linear scaling and lossless compression. Layer-packing stores arrays (instead of a scalar pair) of scalemore » and offset parameters. An implementation of this method is compared with lossless compression, storing data at fixed relative precision (bit-grooming) and scalar linear packing in terms of compression ratio, accuracy and speed. When viewed as a trade-off between compression and error, layer-packing yields similar results to bit-grooming (storing between 3 and 4 significant figures). Bit-grooming and layer-packing offer significantly better control of precision than scalar linear packing. Relative performance, in terms of compression and errors, of bit-groomed and layer-packed data were strongly predicted by the entropy of the exponent array, and lossless compression was well predicted by entropy of the original data array. Layer-packed data files must be "unpacked" to be readily usable. The compression and precision characteristics make layer-packing a competitive archive format for many scientific data sets.« less

Amphibian Symbiotic Bacteria Do Not Show a Universal Ability To Inhibit Growth of the Global Panzootic Lineage of Batrachochytrium dendrobatidis.

PubMed

Antwis, Rachael E; Preziosi, Richard F; Harrison, Xavier A; Garner, Trenton W J

2015-06-01

Microbiomes associated with multicellular organisms influence the disease susceptibility of hosts. The potential exists for such bacteria to protect wildlife from infectious diseases, particularly in the case of the globally distributed and highly virulent fungal pathogen Batrachochytrium dendrobatidis of the global panzootic lineage (B. dendrobatidis GPL), responsible for mass extinctions and population declines of amphibians. B. dendrobatidis GPL exhibits wide genotypic and virulence variation, and the ability of candidate probiotics to restrict growth across B. dendrobatidis isolates has not previously been considered. Here we show that only a small proportion of candidate probiotics exhibited broad-spectrum inhibition across B. dendrobatidis GPL isolates. Moreover, some bacterial genera showed significantly greater inhibition than others, but overall, genus and species were not particularly reliable predictors of inhibitory capabilities. These findings indicate that bacterial consortia are likely to offer a more stable and effective approach to probiotics, particularly if related bacteria are selected from genera with greater antimicrobial capabilities. Together these results highlight a complex interaction between pathogens and host-associated symbiotic bacteria that will require consideration in the development of bacterial probiotics for wildlife conservation. Future efforts to construct protective microbiomes should incorporate bacteria that exhibit broad-spectrum inhibition of B. dendrobatidis GPL isolates. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Ultra-low output impedance RF power amplifier for parallel excitation.

PubMed

Chu, Xu; Yang, Xing; Liu, Yunfeng; Sabate, Juan; Zhu, Yudong

2009-04-01

Inductive coupling between coil elements of a transmit array is one of the key challenges faced by parallel RF transmission. An ultra-low output impedance RF power amplifier (PA) concept was introduced to address this challenge. In an example implementation, an output-matching network was designed to transform the drain-source impedance of the metallic oxide semiconductor field effect transistor (MOSFET) into a very low value for suppressing interelement coupling effect, and meanwhile, to match the input impedance of the coil to the optimum load of the MOSFET for maximizing the available output power. Two prototype amplifiers with 500-W output rating were developed accordingly, and were further evaluated with a transmit array in phantom experiments. Compared to the conventional 50-Omega sources, the new approach exhibited considerable effectiveness suppressing the effects of interelement coupling. The experiments further indicated that the isolation performance was comparable to that achieved by optimized overlap decoupling. The new approach, benefiting from a distinctive current-source characteristic, also exhibited a superior robustness against load variation. Feasibility of the new approach in high-field MR was demonstrated on a 3T clinical scanner.

The day/night proteome in the murine heart.

PubMed

Podobed, Peter; Pyle, W Glen; Ackloo, Suzanne; Alibhai, Faisal J; Tsimakouridze, Elena V; Ratcliffe, William F; Mackay, Allison; Simpson, Jeremy; Wright, David C; Kirby, Gordon M; Young, Martin E; Martino, Tami A

2014-07-15

Circadian rhythms are essential to cardiovascular health and disease. Temporal coordination of cardiac structure and function has focused primarily at the physiological and gene expression levels, but these analyses are invariably incomplete, not the least because proteins underlie many biological processes. The purpose of this study was to reveal the diurnal cardiac proteome and important contributions to cardiac function. The 24-h day-night murine cardiac proteome was assessed by two-dimensional difference in gel electrophoresis (2D-DIGE) and liquid chromatography-mass spectrometry. Daily variation was considerable, as ∼7.8% (90/1,147) of spots exhibited statistical changes at paired times across the 24-h light- (L) dark (D) cycle. JTK_CYCLE was used to investigate underlying diurnal rhythms in corresponding mRNA. We next revealed that disruption of the L:D cycle altered protein profiles and diurnal variation in cardiac function in Langendorff-perfused hearts, relative to the L:D cycle. To investigate the role of the circadian clock mechanism, we used cardiomyocyte clock mutant (CCM) mice. CCM myofilaments exhibited a loss of time-of-day-dependent maximal calcium-dependent ATP consumption, and altered phosphorylation rhythms. Moreover, the cardiac proteome was significantly altered in CCM hearts, especially enzymes regulating vital metabolic pathways. Lastly, we used a model of pressure overload cardiac hypertrophy to demonstrate the temporal proteome during heart disease. Our studies demonstrate that time of day plays a direct role in cardiac protein abundance and indicate a novel mechanistic contribution of circadian biology to cardiovascular structure and function.

The day/night proteome in the murine heart

PubMed Central

Podobed, Peter; Pyle, W. Glen; Ackloo, Suzanne; Alibhai, Faisal J.; Tsimakouridze, Elena V.; Ratcliffe, William F.; Mackay, Allison; Simpson, Jeremy; Wright, David C.; Kirby, Gordon M.; Young, Martin E.

2014-01-01

Circadian rhythms are essential to cardiovascular health and disease. Temporal coordination of cardiac structure and function has focused primarily at the physiological and gene expression levels, but these analyses are invariably incomplete, not the least because proteins underlie many biological processes. The purpose of this study was to reveal the diurnal cardiac proteome and important contributions to cardiac function. The 24-h day-night murine cardiac proteome was assessed by two-dimensional difference in gel electrophoresis (2D-DIGE) and liquid chromatography-mass spectrometry. Daily variation was considerable, as ∼7.8% (90/1,147) of spots exhibited statistical changes at paired times across the 24-h light- (L) dark (D) cycle. JTK_CYCLE was used to investigate underlying diurnal rhythms in corresponding mRNA. We next revealed that disruption of the L:D cycle altered protein profiles and diurnal variation in cardiac function in Langendorff-perfused hearts, relative to the L:D cycle. To investigate the role of the circadian clock mechanism, we used cardiomyocyte clock mutant (CCM) mice. CCM myofilaments exhibited a loss of time-of-day-dependent maximal calcium-dependent ATP consumption, and altered phosphorylation rhythms. Moreover, the cardiac proteome was significantly altered in CCM hearts, especially enzymes regulating vital metabolic pathways. Lastly, we used a model of pressure overload cardiac hypertrophy to demonstrate the temporal proteome during heart disease. Our studies demonstrate that time of day plays a direct role in cardiac protein abundance and indicate a novel mechanistic contribution of circadian biology to cardiovascular structure and function. PMID:24789993

Analytical and between-subject variation of thrombin generation measured by calibrated automated thrombography on plasma samples.

PubMed

Kristensen, Anne F; Kristensen, Søren R; Falkmer, Ursula; Münster, Anna-Marie B; Pedersen, Shona

2018-05-01

The Calibrated Automated Thrombography (CAT) is an in vitro thrombin generation (TG) assay that holds promise as a valuable tool within clinical diagnostics. However, the technique has a considerable analytical variation, and we therefore, investigated the analytical and between-subject variation of CAT systematically. Moreover, we assess the application of an internal standard for normalization to diminish variation. 20 healthy volunteers donated one blood sample which was subsequently centrifuged, aliquoted and stored at -80 °C prior to analysis. The analytical variation was determined on eight runs, where plasma from the same seven volunteers was processed in triplicates, and for the between-subject variation, TG analysis was performed on plasma from all 20 volunteers. The trigger reagents used for the TG assays included both PPP reagent containing 5 pM tissue factor (TF) and PPPlow with 1 pM TF. Plasma, drawn from a single donor, was applied to all plates as an internal standard for each TG analysis, which subsequently was used for normalization. The total analytical variation for TG analysis performed with PPPlow reagent is 3-14% and 9-13% for PPP reagent. This variation can be minimally reduced by using an internal standard but mainly for ETP (endogenous thrombin potential). The between-subject variation is higher when using PPPlow than PPP and this variation is considerable higher than the analytical variation. TG has a rather high inherent analytical variation but considerable lower than the between-subject variation when using PPPlow as reagent.

Relationships between environmental conditions and the morphological variability of planktonic testate amoeba in four neotropical floodplains.

PubMed

Arrieira, Rodrigo Leite; Schwind, Leilane Talita Fatoreto; Joko, Ciro Yoshio; Alves, Geziele Mucio; Velho, Luiz Felipe Machado; Lansac-Tôha, Fábio Amodêo

2016-10-01

Planktonic testate amoebae in floodplains exhibit a broad-range of morphological variability. The variation size is already known, but it is necessary to know how this is for morphological variables. This study aimed to identify the relationships between testate amoebae morphology and environmental factors in four neotropical floodplains. We conducted detailed morphometric analyses on 27 common species of planktonic testate amoebae from genera Arcella, Centropyxis, Cucurbitella, Suiadifflugia, Difflugia, Lesquereusia and Netzelia. We sampled subsurface water from each lake in 72 lakes in four Brazilian floodplain lakes. Our goals were to assess: (1) the range of their morphological variability (a) over space within each floodplain, and (b) among the four floodplains, and (c) over time, and (2) which environmental factors explained this variation. Mean shell height and breadth varied considerably among the different floodplain lakes, especially in the Pantanal and Amazonian floodplains. The morphological variability of testate amoeba was correlated to environmental conditions (ammonia, nitrate, phosphate, chlorophyll-a, turbidity, temperature, and depth). Thus, understanding the morphological variation of the testate amoeba species can elucidate many questions involving the ecology of these organisms. Furthermore, could help molecular studies, bioindicator role of these organisations, environmental reconstruction, among others. Copyright © 2016 Elsevier GmbH. All rights reserved.

Effects of microwave electric fields on the translational diffusion of dipolar molecules in surface potential: A simulation study

NASA Astrophysics Data System (ADS)

Kapranov, Sergey V.; Kouzaev, Guennadi A.

2018-01-01

Variations of effective diffusion coefficient of polar molecules exposed to microwave electric fields in a surface potential are studied by solving coupled stochastic differential equations of motion with a deterministic component of the surface force. Being an essential tool for the simulation interpretation, a theoretical approach to effective diffusion in surface potential is first developed. The effective diffusion coefficient is represented as the product of the normal diffusion coefficient and potential-dependent correction function, whose temperature dependence is close to the Arrhenius form. The analytically found zero-diffusion condition defines the state of thermal equilibrium at the surface. The diffusion of a water-like dipole molecule in the potential of graphite surface is simulated in the field-free conditions and in the presence of the alternating electric fields of various magnitude intensities and frequencies. Temperature dependence of the correction function exhibits field-induced variations of the effective Lennard-Jones energy parameter. It demonstrates maximum departure from the zero-field value at certain frequencies and intensities, which is associated with variations in the rotational dynamics. A concept of the amplitude-frequency resonance put forward to interpret the simulation results is explained using a heuristic reasoning and is corroborated by semi-quantitative considerations in terms of the Dissado-Hill cluster theory of dielectric relaxation.

Detection of exudates in fundus imagery using a constant false-alarm rate (CFAR) detector

NASA Astrophysics Data System (ADS)

Khanna, Manish; Kapoor, Elina

2014-05-01

Diabetic retinopathy is the leading cause of blindness in adults in the United States. The presence of exudates in fundus imagery is the early sign of diabetic retinopathy so detection of these lesions is essential in preventing further ocular damage. In this paper we present a novel technique to automatically detect exudates in fundus imagery that is robust against spatial and temporal variations of background noise. The detection threshold is adjusted dynamically, based on the local noise statics around the pixel under test in order to maintain a pre-determined, constant false alarm rate (CFAR). The CFAR detector is often used to detect bright targets in radar imagery where the background clutter can vary considerably from scene to scene and with angle to the scene. Similarly, the CFAR detector addresses the challenge of detecting exudate lesions in RGB and multispectral fundus imagery where the background clutter often exhibits variations in brightness and texture. These variations present a challenge to common, global thresholding detection algorithms and other methods. Performance of the CFAR algorithm is tested against a publicly available, annotated, diabetic retinopathy database and preliminary testing suggests that performance of the CFAR detector proves to be superior to techniques such as Otsu thresholding.

Evolution of sperm structure and energetics in passerine birds

PubMed Central

Rowe, Melissah; Laskemoen, Terje; Johnsen, Arild; Lifjeld, Jan T.

2013-01-01

Spermatozoa exhibit considerable interspecific variability in size and shape. Our understanding of the adaptive significance of this diversity, however, remains limited. Determining how variation in sperm structure translates into variation in sperm performance will contribute to our understanding of the evolutionary diversification of sperm form. Here, using data from passerine birds, we test the hypothesis that longer sperm swim faster because they have more available energy. We found that sperm with longer midpieces have higher levels of intracellular adenosine triphosphate (ATP), but that greater energy reserves do not translate into faster-swimming sperm. Additionally, we found that interspecific variation in sperm ATP concentration is not associated with the level of sperm competition faced by males. Finally, using Bayesian methods, we compared the evolutionary trajectories of sperm morphology and ATP content, and show that both traits have undergone directional evolutionary change. However, in contrast to recent suggestions in other taxa, we show that changes in ATP are unlikely to have preceded changes in morphology in passerine sperm. These results suggest that variable selective pressures are likely to have driven the evolution of sperm traits in different taxa, and highlight fundamental biological differences between taxa with internal and external fertilization, as well as those with and without sperm storage. PMID:23282997

Regional variations in upper mantle compressional velocities beneath southern California 1. Post-shock temperatures: Their experimental determination, calculation, and implications, 2.. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Raikes, S. A.

1978-01-01

The compressional velocity within the upper mantle beneath Southern California is investigated through observations of the dependence of teleseismic P-delays at all stations of the array on the distance and azimuth to the event. The variation of residuals with azimuth was found to be as large as 1.3 sec at a single station; the delays were stable as a function of time, and no evidence was found for temporal velocity variations related to seismic activity in the area. These delays were used in the construction of models for the upper mantle P-velocity structure to depths of 150 km, both by ray tracing and inversion techniques. The models exhibit considerable lateral heterogeneity including a region of low velocity beneath the Imperial Valley, and regions of increased velocity beneath the Sierra Nevada and much of the Transverse Ranges. The development is described of a technique for the experimental determination of post-shock temperatures, and its application to several metals and silicates shocked to pressures in the range 5 to 30 GPa. The technique utilizes an infra-red radiation detector to determine the brightness temperature of the free surface of the sample after the shock wave has passed through it.

Evolution of Martian polar landscapes - Interplay of long-term variations in perennial ice cover and dust storm intensity

NASA Technical Reports Server (NTRS)

Cutts, J. A.; Blasius, K. R.; Roberts, W. J.

1979-01-01

The discovery of a new type of Martian polar terrain, called undulating plain, is reported and the evolution of the plains and other areas of the Martian polar region is discussed in terms of the trapping of dust by the perennial ice cover. High-resolution Viking Orbiter 2 observations of the north polar terrain reveal perennially ice-covered surfaces with low relief, wavelike, regularly spaced, parallel ridges and troughs (undulating plains) occupying areas of the polar terrain previously thought to be flat, and associated with troughs of considerable local relief which exhibit at least partial annual melting. It is proposed that the wavelike topography of the undulating plains originates from long-term periodic variations in cyclical dust precipitation at the margin of a growing or receding perennial polar cap in response to changes in insolation. The troughs are proposed to originate from areas of steep slope in the undulating terrain which have lost their perennial ice cover and have become incapable of trapping dust. The polar landscape thus appears to record the migrations, expansions and contractions of the Martian polar cap.

Aerodynamic Loading Characteristics at Mach Numbers from 0.80 to 1.20 of a 1/10-Scale Three-Stage Scout Model

NASA Technical Reports Server (NTRS)

Kelly, Thomas C.

1961-01-01

Aerodynamic loads results have been obtained in the Langley 8-foot transonic pressure tunnel at Mach numbers from 0.80 to 1.20 for a 1/10-scale model of the upper three stages of the Scout vehicle. Tests were conducted through an angle-of-attack range from -8 deg to 8 deg at an average test Reynolds number per foot of about 4.0 x 10(exp 6). Results indicated that the peak negative pressures associated with expansion corners at the nose and transition flare exhibit sizeable variations which occur over a relatively small Mach number range. The magnitude of the variations may cause the critical local loading condition for the full-scale vehicle to occur at a Mach number considerably lower than that at which the maximum dynamic pressure occurs in flight. The addition of protuberances simulating antennas and wiring conduits had slight, localized effects. The lift carryover from the nose and transition flare on the cylindrical portions of the model generally increased with an increase in Mach number.

Interactions between marine biota and ENSO: a conceptual model analysis

NASA Astrophysics Data System (ADS)

Heinemann, M.; Timmermann, A.; Feudel, U.

2011-01-01

We develop a conceptual coupled atmosphere-ocean-ecosystem model for the tropical Pacific to investigate the interaction between marine biota and the El Niño-Southern Oscillation (ENSO). Ocean and atmosphere are represented by a two-box model for the equatorial Pacific cold tongue and the warm pool, including a simplified mixed layer scheme. Marine biota are represented by a three-component (nutrient, phytoplankton, and zooplankton) ecosystem model. The atmosphere-ocean model exhibits an oscillatory state which qualitatively captures the main physics of ENSO. During an ENSO cycle, the variation of nutrient upwelling, and, to a small extent, the variation of photosynthetically available radiation force an ecosystem oscillation. The simplified ecosystem in turn, due to the effect of phytoplankton on the absorption of shortwave radiation in the water column, leads to (1) a warming of the tropical Pacific, (2) a reduction of the ENSO amplitude, and (3) a prolongation of the ENSO period. We qualitatively investigate these bio-physical coupling mechanisms using continuation methods. It is demonstrated that bio-physical coupling may play a considerable role in modulating ENSO variability.

Supercritical droplet combustion and related transport phenomena

NASA Technical Reports Server (NTRS)

Yang, Vigor; Hsieh, K. C.; Shuen, J. S.

1993-01-01

An overview of recent advances in theoretical analyses of supercritical droplet vaporization and combustion is conducted. Both hydrocarbon and cryogenic liquid droplets over a wide range of thermodynamic states are considered. Various important high-pressure effects on droplet behavior, such as thermodynamic non-ideality, transport anomaly, and property variation, are reviewed. Results indicate that the ambient gas pressure exerts significant control of droplet gasification and burning processes through its influence on fluid transport, gas-liquid interfacial thermodynamics, and chemical reactions. The droplet gasification rate increases progressively with pressure. However, the data for the overall burnout time exhibit a considerable change in the combustion mechanism at the criticl pressure, mainly as a result of reduced mass diffusivity and latent heat of vaporization with increased pressure. The influence of droplet size on the burning characteristics is also noted.

I. Sexual, individual, and geographical variation in leucosticte tephrocotis, II.Geographical variation among North American mammals, especially in respect to size

USGS Publications Warehouse

Allen, J.A.

1876-01-01

Having recently had an opportunity (through the kindness of Professor Baird) of studying with some care the magnificent series of skulls of the North American Mammalia belonging to the National Museum (amounting often to eighty or a hundred specimens of a single species), I have been strongly impressed with the different degrees of variability exhibited by the representatives of the species and genera of even the same family. The variation in size, for instance, with latitude, in the Wolves and Foxes is surprisingly great, amounting in some species (as will be shown later) to 25 per cent. of the average size of the species, while in other species of the Ferae it is almost nil. Contrary to the general supposition, the variation in size among representatives of the same species is not always a decrease with the decrease of the latitude of the locality, but is in some cases exactly the reverse, in some species there being a very considerable and indisputable increase southward. This, for instance, is very markedly true of some species of Felis and in Procyon lotor. Consequently, the very generally-received impression that in North America the species of Mammalia diminish in size southward, or with the decrease in the latitude (and altitude) of the locality, requires modification. While such is generally the case, the reverse of this too often occurs, with occasional instances also of a total absence of variation in size with locality, to be considered as forming "the exceptions" necessary to "prove the rule".

Individual differences in migratory behavior shape population genetic structure and microhabitat choice in sympatric blackcaps (Sylvia atricapilla)

PubMed Central

Rolshausen, Gregor; Segelbacher, Gernot; Hermes, Claudia; Hobson, Keith A; Schaefer, H Martin

2013-01-01

In migratory birds, traits such as orientation and distance are known to have a strong genetic background, and they often exhibit considerable within-population variation. How this variation relates to evolutionary responses to ongoing selection is unknown because the underlying mechanisms that translate environmental changes into population genetic changes are unclear. We show that within-population genetic structure in southern German blackcaps (Sylvia atricapilla) is related to individual differences in migratory behavior. Our 3-year study revealed a positive correlation between individual migratory origins, denoted via isotope (δ2H) values, and genetic distances. Genetic diversity and admixture differed not only across a recently established migratory polymorphism with NW- and SW-migrating birds but also across δ2H clusters within the same migratory route. Our results suggest assortment based on individual migratory origins which would facilitate evolutionary responses. We scrutinized arrival times and microhabitat choice as potential mechanisms mediating between individual variation in migratory behavior and assortment. We found significant support that microhabitat choice, rather than timing of arrival, is associated with individual variation in migratory origins. Moreover, examining genetic diversity across the migratory divide, we found migrants following the NW route to be genetically more distinct from each other compared with migrants following the traditional SW route. Our study suggests that migratory behavior shapes population genetic structure in blackcaps not only across the migratory divide but also on an individual level independent of the divide. Thus, within-population variation in migratory behavior might play an important role in translating environmental change into genetic change. PMID:24324877

Unusual properties of high-compliance porosity extracted from measurements of pressure-dependent wave velocities in rocks

NASA Astrophysics Data System (ADS)

Zaitsev, Vladimir Y.; Radostin, Andrey V.; Pasternak, Elena; Dyskin, Arcady

2016-04-01

Conventionally the interpretation of wave velocities and their variations under load is conducted assuming that closable cracks have simple planar shapes, like the popular model of penny-shape cracks. For such cracks, the proportion between complementary variations in different elastic parameters of rocks (such as S- and P-wave velocities) is strictly pre-determined, in particular, it is independent of the crack aspect ratio and rather weakly dependent on the Poisson's ratio of the intact rock. Real rocks, however, contain multitude of cracks of different geometry. Faces of such cracks can exhibit complex modes of interaction when closed by external load, which may result in very different ratios between normal- and shear compliances of such defects. In order to describe the reduction of different elastic moduli, we propose a model in which the compliances of crack-like defects are explicitly decoupled and are not predetermined, so that the ratio q between total normal- and shear- compliances imparted to the rock mass (as well as individual values of these compliances) can be estimated from experimental data on reduction of different elastic moduli (e.g., pressure dependences of P- and S-wave velocities). Physically, the so-extracted ratio q can be interpreted as intrinsic property of individual crack-like defects similar to each other, or as a characteristic of proportion between concentrations of pure normal cracks with very large q and pure shear cracks with q→0. The latter case can correspond, e.g., to saturated cracks in which weakly-compressible liquid prevents crack closing under normal loading. It can be shown that for conventional dry planar cracks, the compliance ratio is q ˜2. The developed model applied to the data on wave-velocity variations with external pressure indicates that elastic properties of the real crack-like defects in rocks can differ considerably from the usually assumed ones. Comparison with experimental data on variations P- and S-wave velocities with hydrostatic compression of different dry and saturated rocks (sandstones, Westerly granite and Webatuck dolomite, etc.) shows that our model is accurate in a wide range of pressures with constant (i.e., pressure-independent) values of parameter q. Furthermore, the determined values of the latter are considerably different from those of conventional cracks. In particular, although all saturated samples have values q <1, the simplified approximation q=0 (i.e., the absence of normal compressibility that is often assumed for wet cracks) leads to large errors in the prediction of complementary variations in the shear- and bulk elastic moduli. Among dry sandstones, the majority have q >2 and many sandstones exhibit unusually high q»1 suggesting quite rough and tortoise nature of real cracks in those rocks. We demonstrate that in such cases, the use of the conventional assumption q ˜2 typical of penny-shape cracks leads to striking inconsistency between the predicted and experimentally observed crack-induced complementary variations in different elastic moduli. Furthermore, among samples with q»1, we revealed numerous examples that demonstrate negative Poisson's ratio at low pressures. VYZ and AVR acknowledge the financial support by RFBR grant No 15-05-05143.

Spatial-temporal patterns and driving mechanisms of semiannual variations in the Philippine Sea

NASA Astrophysics Data System (ADS)

Zhao, Jun; Li, Yuanlong; Wang, Fan; Zhai, Fangguo; Yu, Xiaolin

2012-10-01

Satellite altimetric sea surface height (SSH) measurements from 1992 through 2010 are used to explore the oceanic semiannual variations in the Philippine Sea (PS). Pronounced semiannual SSH variations are detected within two zonal bands. One lies east of Luzon Strait (19°-22°N) in the northern PS, while the other is southeast of Mindanao coast (4°-7°N) in the southern PS. In the two near-coast boxes where semiannual harmonic amplitude exceeds 4 cm, the northern box (127°-133°E, 19°-22°N) and the southern box (127°-133°E, 4°-7°N), semiannual changes contribute considerably to the total annual SSH variance by 12% and 17%, respectively. Despite prominent SSH variability, the bifurcation latitude of the North Equatorial Current (NBL) exhibits weak fluctuations with a peak-to-peak difference of only 0.3° on semiannual time scale. While the in-phase annual SSH variations between the two boxes work together to enhance annual NBL changes, their out-of-phase semiannual SSH variations offset each other in driving the NBL displacements. Further analysis with a 11/2-layer reduced-gravity model forced by ECMWF wind stress reveals that the observed semiannual SSH variations are primarily driven by local wind forcing in the far western Pacific. Rossby wave signals propagating from the eastern/central Pacific contribute much less due to along-path dispersion and cancellation. Semiannual signals of wind field in the northern PS reflect mainly the semiannual changes of the Asian Monsoon system, while those in the southern PS arise from the combined effects of Monsoon transition and the annual migration of the intertropical convergence zone (ITCZ).

Spiders do not escape reproductive manipulations by Wolbachia

PubMed Central

2011-01-01

Background Maternally inherited bacteria that reside obligatorily or facultatively in arthropods can increase their prevalence in the population by altering their hosts' reproduction. Such reproductive manipulations have been reported from the major arthropod groups such as insects (in particular hymenopterans, butterflies, dipterans and beetles), crustaceans (isopods) and mites. Despite the observation that endosymbiont bacteria are frequently encountered in spiders and that the sex ratio of particular spider species is strongly female biased, a direct relationship between bacterial infection and sex ratio variation has not yet been demonstrated for this arthropod order. Results Females of the dwarf spider Oedothorax gibbosus exhibit considerable variation in the sex ratio of their clutches and were infected with at least three different endosymbiont bacteria capable of altering host reproduction i.e. Wolbachia, Rickettsia and Cardinium. Breeding experiments show that sex ratio variation in this species is primarily maternally inherited and that removal of the bacteria by antibiotics restores an unbiased sex ratio. Moreover, clutches of females infected with Wolbachia were significantly female biased while uninfected females showed an even sex ratio. As female biased clutches were of significantly smaller size compared to non-distorted clutches, killing of male embryos appears to be the most likely manipulative effect. Conclusions This represents to our knowledge the first direct evidence that endosymbiont bacteria, and in particular Wolbachia, might induce sex ratio variation in spiders. These findings are pivotal to further understand the diversity of reproductive phenotypes observed in this arthropod order. PMID:21235755

Variation in the molecular clock of primates.

PubMed

Moorjani, Priya; Amorim, Carlos Eduardo G; Arndt, Peter F; Przeworski, Molly

2016-09-20

Events in primate evolution are often dated by assuming a constant rate of substitution per unit time, but the validity of this assumption remains unclear. Among mammals, it is well known that there exists substantial variation in yearly substitution rates. Such variation is to be expected from differences in life history traits, suggesting it should also be found among primates. Motivated by these considerations, we analyze whole genomes from 10 primate species, including Old World Monkeys (OWMs), New World Monkeys (NWMs), and apes, focusing on putatively neutral autosomal sites and controlling for possible effects of biased gene conversion and methylation at CpG sites. We find that substitution rates are up to 64% higher in lineages leading from the hominoid-NWM ancestor to NWMs than to apes. Within apes, rates are ∼2% higher in chimpanzees and ∼7% higher in the gorilla than in humans. Substitution types subject to biased gene conversion show no more variation among species than those not subject to it. Not all mutation types behave similarly, however; in particular, transitions at CpG sites exhibit a more clocklike behavior than do other types, presumably because of their nonreplicative origin. Thus, not only the total rate, but also the mutational spectrum, varies among primates. This finding suggests that events in primate evolution are most reliably dated using CpG transitions. Taking this approach, we estimate the human and chimpanzee divergence time is 12.1 million years,​ and the human and gorilla divergence time is 15.1 million years​.

The Effect of Fiber Strength Stochastics and Local Fiber Volume Fraction on Multiscale Progressive Failure of Composites

NASA Technical Reports Server (NTRS)

Ricks, Trenton M.; Lacy, Jr., Thomas E.; Bednarcyk, Brett A.; Arnold, Steven M.

2013-01-01

Continuous fiber unidirectional polymer matrix composites (PMCs) can exhibit significant local variations in fiber volume fraction as a result of processing conditions that can lead to further local differences in material properties and failure behavior. In this work, the coupled effects of both local variations in fiber volume fraction and the empirically-based statistical distribution of fiber strengths on the predicted longitudinal modulus and local tensile strength of a unidirectional AS4 carbon fiber/ Hercules 3502 epoxy composite were investigated using the special purpose NASA Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC); local effective composite properties were obtained by homogenizing the material behavior over repeating units cells (RUCs). The predicted effective longitudinal modulus was relatively insensitive to small (8%) variations in local fiber volume fraction. The composite tensile strength, however, was highly dependent on the local distribution in fiber strengths. The RUC-averaged constitutive response can be used to characterize lower length scale material behavior within a multiscale analysis framework that couples the NASA code FEAMAC and the ABAQUS finite element solver. Such an approach can be effectively used to analyze the progressive failure of PMC structures whose failure initiates at the RUC level. Consideration of the effect of local variations in constituent properties and morphologies on progressive failure of PMCs is a central aspect of the application of Integrated Computational Materials Engineering (ICME) principles for composite materials.

Extremes in East African hydroclimate and links to Indo-Pacific variability on interannual to decadal timescales

NASA Astrophysics Data System (ADS)

Ummenhofer, Caroline C.; Kulüke, Marco; Tierney, Jessica E.

2018-04-01

East African hydroclimate exhibits considerable variability across a range of timescales, with implications for its population that depends on the region's two rainy seasons. Recent work demonstrated that current state-of-the-art climate models consistently underestimate the long rains in boreal spring over the Horn of Africa while overestimating the short rains in autumn. This inability to represent the seasonal cycle makes it problematic for climate models to project changes in East African precipitation. Here we consider whether this bias also has implications for understanding interannual and decadal variability in the East African long and short rains. Using a consistent framework with an unforced multi-century global coupled climate model simulation, the role of Indo-Pacific variability for East African rainfall is compared across timescales and related to observations. The dominant driver of East African rainfall anomalies critically depends on the timescale under consideration: Interannual variations in East African hydroclimate coincide with significant sea surface temperature (SST) anomalies across the Indo-Pacific, including those associated with the El Niño-Southern Oscillation (ENSO) in the eastern Pacific, and are linked to changes in the Walker circulation, regional winds and vertical velocities over East Africa. Prolonged drought/pluvial periods in contrast exhibit anomalous SST predominantly in the Indian Ocean and Indo-Pacific warm pool (IPWP) region, while eastern Pacific anomalies are insignificant. We assessed dominant frequencies in Indo-Pacific SST and found the eastern equatorial Pacific dominated by higher-frequency variability in the ENSO band, while the tropical Indian Ocean and IPWP exhibit lower-frequency variability beyond 10 years. This is consistent with the different contribution to regional precipitation anomalies for the eastern Pacific versus Indian Ocean and IPWP on interannual and decadal timescales, respectively. In the model, the dominant low-frequency signal seen in the observations in the Indo-Pacific is not well-represented as it instead exhibits overly strong variability on subdecadal timescales. The overly strong ENSO-teleconnection likely contributes to the overestimated role of the short rains in the seasonal cycle in the model compared to observations.

Interannual Variations and Trends in Global Land Surface Phenology Derived from Enhanced Vegetation Index During 1982-2010

NASA Technical Reports Server (NTRS)

Zhang, Xiaoyang; Tan, Bin; Yu, Yunyue

2014-01-01

Land swiace phenology is widely retrieved from satellite observations at regional and global scales, and its long-term record has been demonstmted to be a valuable tool for reconstructing past climate variations, monitoring the dynamics of terrestrial ecosystems in response to climate impacts, and predicting biological responses to future climate scenarios. This srudy detected global land surface phenology from the advanced very high resolution radiometer (AVHRR) and the Moderate Resolution Imaging Spectroradiometer (MODIS) data from 1982 to 2010. Based on daily enhanced vegetation index at a spatial resolution of 0.05 degrees, we simulated the seasonal vegetative trajectory for each individual pixel using piecewise logistic models, which was then used to detect the onset of greenness increase (OGI) and the length of vegetation growing season (GSL). Further, both overall interannual variations and pixel-based trends were examIned across Koeppen's climate regions for the periods of 1982-1999 and 2000-2010, respectively. The results show that OGI and OSL varied considerably during 1982-2010 across the globe. Generally, the interarmual variation could be more than a month in precipitation-controlled tropical and dry climates while it was mainly less than 15 days in temperature-controlled temperate, cold, and polar climates. OGI, overall, shifted early, and GSL was prolonged from 1982 to 2010 in most climate regions in North America and Asia while the consistently significant trends only occurred in cold climate and polar climate in North America. The overall trends in Europe were generally insignificant. Over South America, late OGI was consistent (particularly from 1982 to 1999) while either positive or negative OSL trends in a climate region were mostly reversed between the periods of 1982-1999 and 2000-2010. In the Northern Hemisphere of Africa, OGI trends were mostly insignificant, but prolonged GSL was evident over individual climate regions during the last 3 decades. OGI mainly showed late trends in the Southern Hemisphere of Africa while GSL was reversed from reduced GSL trends (1982-1999) to prolonged trends (2000-2010). In Australia, GSL exhibited considerable interannual variation, but the consistent trend lacked presence in most regions. Finally, the proportion of pixels with significant trends was less than I% in most of climate regions although it could be as large as 10%.

Interannual variations and trends in global land surface phenology derived from enhanced vegetation index during 1982-2010

NASA Astrophysics Data System (ADS)

Zhang, Xiaoyang; Tan, Bin; Yu, Yunyue

2014-05-01

Land surface phenology is widely retrieved from satellite observations at regional and global scales, and its long-term record has been demonstrated to be a valuable tool for reconstructing past climate variations, monitoring the dynamics of terrestrial ecosystems in response to climate impacts, and predicting biological responses to future climate scenarios. This study detected global land surface phenology from the advanced very high resolution radiometer (AVHRR) and the Moderate Resolution Imaging Spectroradiometer (MODIS) data from 1982 to 2010. Based on daily enhanced vegetation index at a spatial resolution of 0.05 degrees, we simulated the seasonal vegetative trajectory for each individual pixel using piecewise logistic models, which was then used to detect the onset of greenness increase (OGI) and the length of vegetation growing season (GSL). Further, both overall interannual variations and pixel-based trends were examined across Koeppen's climate regions for the periods of 1982-1999 and 2000-2010, respectively. The results show that OGI and GSL varied considerably during 1982-2010 across the globe. Generally, the interannual variation could be more than a month in precipitation-controlled tropical and dry climates while it was mainly less than 15 days in temperature-controlled temperate, cold, and polar climates. OGI, overall, shifted early, and GSL was prolonged from 1982 to 2010 in most climate regions in North America and Asia while the consistently significant trends only occurred in cold climate and polar climate in North America. The overall trends in Europe were generally insignificant. Over South America, late OGI was consistent (particularly from 1982 to 1999) while either positive or negative GSL trends in a climate region were mostly reversed between the periods of 1982-1999 and 2000-2010. In the Northern Hemisphere of Africa, OGI trends were mostly insignificant, but prolonged GSL was evident over individual climate regions during the last 3 decades. OGI mainly showed late trends in the Southern Hemisphere of Africa while GSL was reversed from reduced GSL trends (1982-1999) to prolonged trends (2000-2010). In Australia, GSL exhibited considerable interannual variation, but the consistent trend lacked presence in most regions. Finally, the proportion of pixels with significant trends was less than 1 % in most of climate regions although it could be as large as 10 %.

Deciduousness in a seasonal tropical forest in western Thailand: interannual and intraspecific variation in timing, duration and environmental cues.

PubMed

Williams, Laura J; Bunyavejchewin, Sarayudh; Baker, Patrick J

2008-03-01

Seasonal tropical forests exhibit a great diversity of leaf exchange patterns. Within these forests variation in the timing and intensity of leaf exchange may occur within and among individual trees and species, as well as from year to year. Understanding what generates this diversity of phenological behaviour requires a mechanistic model that incorporates rate-limiting physiological conditions, environmental cues, and their interactions. In this study we examined long-term patterns of leaf flushing for a large proportion of the hundreds of tree species that co-occur in a seasonal tropical forest community in western Thailand. We used the data to examine community-wide variation in deciduousness and tested competing hypotheses regarding the timing and triggers of leaf flushing in seasonal tropical forests. We developed metrics to quantify the nature of deciduousness (its magnitude, timing and duration) and its variability among survey years and across a range of taxonomic levels. Tree species varied widely in the magnitude, duration, and variability of leaf loss within species and across years. The magnitude of deciduousness ranged from complete crown loss to no crown loss. Among species that lost most of their crown, the duration of deciduousness ranged from 2 to 21 weeks. The duration of deciduousness in the majority of species was considerably shorter than in neotropical forests with similar rainfall periodicity. While the timing of leaf flushing varied among species, most ( approximately 70%) flushed during the dry season. Leaf flushing was associated with changes in photoperiod in some species and the timing of rainfall in other species. However, more than a third of species showed no clear association with either photoperiod or rainfall, despite the considerable length and depth of the dataset. Further progress in resolving the underlying internal and external mechanisms controlling leaf exchange will require targeting these species for detailed physiological and microclimatic studies.

Spatial structure of morphological and neutral genetic variation in Brook Trout

USGS Publications Warehouse

Kazyak, David C.; Hilderbrand, Robert H.; Keller, Stephen R.; Colaw, Mark C.; Holloway, Amanda E.; Morgan, Raymond P.; King, Timothy L.

2015-01-01

Brook Trout Salvelinus fontinalis exhibit exceptional levels of life history variation, remarkable genetic variability, and fine-scale population structure. In many cases, neighboring populations may be highly differentiated from one another to an extent that is comparable with species-level distinctions in other taxa. Although genetic samples have been collected from hundreds of populations and tens of thousands of individuals, little is known about whether differentiation at neutral markers reflects phenotypic differences among Brook Trout populations. We compared differentiation in morphology and neutral molecular markers among populations from four geographically proximate locations (all within 24 km) to examine how genetic diversity covaries with morphology. We found significant differences among and/or within streams for all three morphological axes examined and identified the source stream of many individuals based on morphology (52.3% classification efficiency). Although molecular and morphological differentiation among streams ranged considerably (mean pairwise FST: 0.023–0.264; pairwise PST: 0.000–0.339), the two measures were not significantly correlated. While in some cases morphological characters appear to have diverged to a greater extent than expected by neutral genetic drift, many traits were conserved to a greater extent than were neutral genetic markers. Thus, while Brook Trout exhibit fine-scale spatial patterns in both morphology and neutral genetic diversity, these types of biological variabilities are being structured by different ecological and evolutionary processes. The relative influences of genetic drift versus selection and phenotypic plasticity in shaping morphology appear to vary among populations occupying nearby streams.

Major histocompatibility complex alleles associated with parasite susceptibility in wild giant pandas.

PubMed

Zhang, L; Wu, Q; Hu, Y; Wu, H; Wei, F

2015-01-01

Major histocompatibility complex (MHC) polymorphism is thought to be driven by antagonistic coevolution between pathogens and hosts, mediated through either overdominance or frequency-dependent selection. However, investigations under natural conditions are still rare for endangered mammals which often exhibit depleted variation, and the mechanism of selection underlying the maintenance of characteristics remains a considerable debate. In this study, 87 wild giant pandas were used to investigate MHC variation associated with parasite load. With the knowledge of the MHC profile provided by the genomic data of the giant panda, seven DRB1, seven DQA1 and eight DQA2 alleles were identified at each single locus. Positive selection evidenced by a significantly higher number of non-synonymous substitutions per non-synonymous codon site relative to synonymous substitutions per synonymous codon site could only be detected at the DRB1 locus, which leads to the speculation that DRB1 may have a more important role in dealing with parasite infection for pandas. Coprological analyses revealed that 55.17% of individuals exhibited infection with 1-2 helminthes and 95.3% of infected pandas carried Baylisascaris shroederi. Using a generalized linear model, we found that Aime-DRB1*10 was significantly associated with parasite infection, but no resistant alleles could be detected. MHC heterozygosity of the pandas was found to be uncorrelated with the infection status or the infection intensity. These results suggested that the possible selection mechanisms in extant wild pandas may be frequency dependent rather than being determined by overdominance selection. Our findings could guide the candidate selection for the ongoing reintroduction or translocation of pandas.

Major histocompatibility complex alleles associated with parasite susceptibility in wild giant pandas

PubMed Central

Zhang, L; Wu, Q; Hu, Y; Wu, H; Wei, F

2015-01-01

Major histocompatibility complex (MHC) polymorphism is thought to be driven by antagonistic coevolution between pathogens and hosts, mediated through either overdominance or frequency-dependent selection. However, investigations under natural conditions are still rare for endangered mammals which often exhibit depleted variation, and the mechanism of selection underlying the maintenance of characteristics remains a considerable debate. In this study, 87 wild giant pandas were used to investigate MHC variation associated with parasite load. With the knowledge of the MHC profile provided by the genomic data of the giant panda, seven DRB1, seven DQA1 and eight DQA2 alleles were identified at each single locus. Positive selection evidenced by a significantly higher number of non-synonymous substitutions per non-synonymous codon site relative to synonymous substitutions per synonymous codon site could only be detected at the DRB1 locus, which leads to the speculation that DRB1 may have a more important role in dealing with parasite infection for pandas. Coprological analyses revealed that 55.17% of individuals exhibited infection with 1–2 helminthes and 95.3% of infected pandas carried Baylisascaris shroederi. Using a generalized linear model, we found that Aime-DRB1*10 was significantly associated with parasite infection, but no resistant alleles could be detected. MHC heterozygosity of the pandas was found to be uncorrelated with the infection status or the infection intensity. These results suggested that the possible selection mechanisms in extant wild pandas may be frequency dependent rather than being determined by overdominance selection. Our findings could guide the candidate selection for the ongoing reintroduction or translocation of pandas. PMID:25248466

Exciton in a spherical core/shell nanostructure: Influence of surface ligand

NASA Astrophysics Data System (ADS)

Anitha, B.; Nithiananthi, P.

2018-04-01

Studies on exciton in an inverted type I spherical GaAs/Al0.3Ga0.7As core/shell nanostructure (CSN) are made using variational method. Dielectric constant and effective mass mismatches of the core and shell materials are considered. The effect of core and the shell dimensions on the exciton binding energy (BE) are analyzed for different shell (Rs) and core radii (Rc). It is observed that with the core and the shell inducement, significant change in BE can be achieved. In addition, the influence of ligand enclosureon the BE as a function of shell thickness (ST) is reviewed. The result exhibits that the presence of ligand considerably affects the BE. Further the transmission probability of exciton for various Rc and Rs are reported. The notable changes are compared and examined with and without ligand inclusion.

A spherical harmonics method for asteroid pole determination

NASA Technical Reports Server (NTRS)

Lumme, K.; Karttunen, H.; Bowell, E.

1990-01-01

A new and general method is presented for determining pole orientations of unresolved solar system bodies that exhibit brightness variation with rotation. The accuracy of the method is limited only by the number of available apparitions, which imposes the degree where the Legendre expansion must be truncated. It is shown that power spectra of lightcurves provide enough information to extract pole coordinates from the data, independent of body shape and albedo variegation. The method has been tested using several computer-generated synthetic light-curves, and the accuracy is found to be about 5 deg in both the longitude and latitude of the pole, which is considerably better than that obtained from the standard triaxial ellipsoid model. Finally, the new spherical harmonics method has been applied to six well-observed asteroids: 16 Psyche, 22 Kalliope, 39 Laetitia, 44 Nysa, 45 Eugenia, and 349 Dembowska.

Borderline Personality and Criminality

PubMed Central

Sansone, Lori A.

2009-01-01

Borderline personality disorder is characteristically associated with a broad variety of psychiatric symptoms and aberrant behaviors. In this edition of The Interface, we discuss the infrequently examined association between borderline personality disorder and criminality. According to our review of the literature, in comparison with the rates of borderline personality disorder encountered in the general population, borderline personality disorder is over-represented in most studies of inmates. At the same time, there is considerable variation in the reported rates of this Axis II disorder in prison populations, which may be attributed to the methodologies of and populations in the various studies. Overall, female criminals appear to exhibit higher rates of borderline personality disorder, and it is oftentimes associated with a history of childhood sexual abuse, perpetration of impulsive and violent crimes, comorbid antisocial traits, and incarceration for domestic violence. PMID:20011575

Establishing Quantitative Within-Subject Confidence Limits For Clinical Stereoroentgenographs

NASA Astrophysics Data System (ADS)

Korn, Edward L.; Baumrind, Sheldon; Chafetz, Neil; Curry, Sean; Moffitt, Francis

1983-07-01

It is now quite clear that under ideal conditions, discrete points can be located on x-ray films with standard deviations of less than 50 i. However, under routine clinical conditions, such considerations as individual variation in anatomy, movement of the subject between exposures, and variations in image quality combine to produce considerable reductions in the confidence which can be placed in quantitative assessments made from stereoroentgenographic films. This paper discusses some considerations involved in designing mathematical models in such a way as to optimize the use of imperfect data in answering specific clinical questions.

Species conservation and natural variation among populations [Chapter 5

Treesearch

Leonard F. Ruggiero; Michael K. Schwartz; Keith B. Aubry; Charles J. Krebs; Amanda Stanley; Steven W. Buskirk

2000-01-01

In conservation planning, the importance of natural variation is often given inadequate consideration. However, ignoring the implications of variation within species may result in conservation strategies that jeopardize, rather than conserve, target species (see Grieg 1979; Turcek 1951; Storfer 1999). Natural variation in the traits of individuals and populations is...

The Costs of Delivering Integrated HIV and Sexual Reproductive Health Services in Limited Resource Settings

PubMed Central

Obure, Carol Dayo; Sweeney, Sedona; Darsamo, Vanessa; Michaels-Igbokwe, Christine; Guinness, Lorna; Terris-Prestholt, Fern; Muketo, Esther; Nhlabatsi, Zelda; Warren, Charlotte E.; Mayhew, Susannah; Watts, Charlotte; Vassall, Anna

2015-01-01

Objective To present evidence on the total costs and unit costs of delivering six integrated sexual reproductive health and HIV services in a high and medium HIV prevalence setting, in order to support policy makers and planners scaling up these essential services. Design A retrospective facility based costing study conducted in 40 non-government organization and public health facilities in Kenya and Swaziland. Methods Economic and financial costs were collected retrospectively for the year 2010/11, from each study site with an aim to estimate the cost per visit of six integrated HIV and SRH services. A full cost analysis using a combination of bottom-up and step-down costing methods was conducted from the health provider’s perspective. The main unit of analysis is the economic unit cost per visit for each service. Costs are converted to 2013 International dollars. Results The mean cost per visit for the HIV/SRH services ranged from $Int 14.23 (PNC visit) to $Int 74.21 (HIV treatment visit). We found considerable variation in the unit costs per visit across settings with family planning services exhibiting the least variation ($Int 6.71-52.24) and STI treatment and HIV treatment visits exhibiting the highest variation in unit cost ranging from ($Int 5.44-281.85) and ($Int 0.83-314.95), respectively. Unit costs of visits were driven by fixed costs while variability in visit costs across facilities was explained mainly by technology used and service maturity. Conclusion For all services, variability in unit costs and cost components suggest that potential exists to reduce costs through better use of both human and capital resources, despite the high proportion of expenditure on drugs and medical supplies. Further work is required to explore the key drivers of efficiency and interventions that may facilitate efficiency improvements. PMID:25933414

Campylobacter jejuni transcriptome changes during loss of culturability in water

PubMed Central

Bronowski, Christina; Mustafa, Kasem; Goodhead, Ian; James, Chloe E.; Nelson, Charlotte; Lucaci, Anita; Wigley, Paul; Humphrey, Tom J.; Williams, Nicola J.; Winstanley, Craig

2017-01-01

Background Water serves as a potential reservoir for Campylobacter, the leading cause of bacterial gastroenteritis in humans. However, little is understood about the mechanisms underlying variations in survival characteristics between different strains of C. jejuni in natural environments, including water. Results We identified three Campylobacter jejuni strains that exhibited variability in their ability to retain culturability after suspension in tap water at two different temperatures (4°C and 25°C). Of the three, strains C. jejuni M1 exhibited the most rapid loss of culturability whilst retaining viability. Using RNAseq transcriptomics, we characterised C. jejuni M1 gene expression in response to suspension in water by analyzing bacterial suspensions recovered immediately after introduction into water (Time 0), and from two sampling time/temperature combinations where considerable loss of culturability was evident, namely (i) after 24 h at 25°C, and (ii) after 72 h at 4°C. Transcript data were compared with a culture-grown control. Some gene expression characteristics were shared amongst the three populations recovered from water, with more genes being up-regulated than down. Many of the up-regulated genes were identified in the Time 0 sample, whereas the majority of down-regulated genes occurred in the 25°C (24 h) sample. Conclusions Variations in expression were found amongst genes associated with oxygen tolerance, starvation and osmotic stress. However, we also found upregulation of flagellar assembly genes, accompanied by down-regulation of genes involved in chemotaxis. Our data also suggested a switch from secretion via the sec system to via the tat system, and that the quorum sensing gene luxS may be implicated in the survival of strain M1 in water. Variations in gene expression also occurred in accessory genome regions. Our data suggest that despite the loss of culturability, C. jejuni M1 remains viable and adapts via specific changes in gene expression. PMID:29190673

Scale-dependent behavior of the foredune: Implications for barrier island response to storms and sea-level rise

NASA Astrophysics Data System (ADS)

Houser, Chris; Wernette, Phil; Weymer, Bradley A.

2018-02-01

The impact of storm surge on a barrier island tends to be considered from a single cross-shore dimension, dependent on the relative elevations of the storm surge and dune crest. However, the foredune is rarely uniform and can exhibit considerable variation in height and width at a range of length scales. In this study, LiDAR data from barrier islands in Texas and Florida are used to explore how shoreline position and dune morphology vary alongshore, and to determine how this variability is altered or reinforced by storms and post-storm recovery. Wavelet analysis reveals that a power law can approximate historical shoreline change across all scales, but that storm-scale shoreline change ( 10 years) and dune height exhibit similar scale-dependent variations at swash and surf zone scales (< 1000 m). The in-phase nature of the relationship between dune height and storm-scale shoreline change indicates that areas of greater storm-scale shoreline retreat are associated with areas of smaller dunes. It is argued that the decoupling of storm-scale and historical shoreline change at swash and surf zone scales is also associated with the alongshore redistribution of sediment and the tendency of shorelines to evolve to a more diffusive (or straight) pattern with time. The wavelet analysis of the data for post-storm dune recovery is also characterized by red noise at the smallest scales characteristic of diffusive systems, suggesting that it is possible that small-scale variations in dune height can be repaired through alongshore recovery and expansion if there is sufficient time between storms. However, the time required for dune recovery exceeds the time between storms capable of eroding and overwashing the dune. Correlation between historical shoreline retreat and the variance of the dune at swash and surf zone scales suggests that the persistence of the dune is an important control on transgression through island migration or shoreline retreat with relative sea-level rise.

Variational data assimilation for the initial-value dynamo problem.

PubMed

Li, Kuan; Jackson, Andrew; Livermore, Philip W

2011-11-01

The secular variation of the geomagnetic field as observed at the Earth's surface results from the complex magnetohydrodynamics taking place in the fluid core of the Earth. One way to analyze this system is to use the data in concert with an underlying dynamical model of the system through the technique of variational data assimilation, in much the same way as is employed in meteorology and oceanography. The aim is to discover an optimal initial condition that leads to a trajectory of the system in agreement with observations. Taking the Earth's core to be an electrically conducting fluid sphere in which convection takes place, we develop the continuous adjoint forms of the magnetohydrodynamic equations that govern the dynamical system together with the corresponding numerical algorithms appropriate for a fully spectral method. These adjoint equations enable a computationally fast iterative improvement of the initial condition that determines the system evolution. The initial condition depends on the three dimensional form of quantities such as the magnetic field in the entire sphere. For the magnetic field, conservation of the divergence-free condition for the adjoint magnetic field requires the introduction of an adjoint pressure term satisfying a zero boundary condition. We thus find that solving the forward and adjoint dynamo system requires different numerical algorithms. In this paper, an efficient algorithm for numerically solving this problem is developed and tested for two illustrative problems in a whole sphere: one is a kinematic problem with prescribed velocity field, and the second is associated with the Hall-effect dynamo, exhibiting considerable nonlinearity. The algorithm exhibits reliable numerical accuracy and stability. Using both the analytical and the numerical techniques of this paper, the adjoint dynamo system can be solved directly with the same order of computational complexity as that required to solve the forward problem. These numerical techniques form a foundation for ultimate application to observations of the geomagnetic field over the time scale of centuries.

Experimental evidence for convergent evolution of maternal care heuristics in industrialized and small-scale populations.

PubMed

Kushnick, Geoff; Hanowell, Ben; Kim, Jun-Hong; Langstieh, Banrida; Magnano, Vittorio; Oláh, Katalin

2015-06-01

Maternal care decision rules should evolve responsiveness to factors impinging on the fitness pay-offs of care. Because the caretaking environments common in industrialized and small-scale societies vary in predictable ways, we hypothesize that heuristics guiding maternal behaviour will also differ between these two types of populations. We used a factorial vignette experiment to elicit third-party judgements about likely caretaking decisions of a hypothetical mother and her child when various fitness-relevant factors (maternal age and access to resources, and offspring age, sex and quality) were varied systematically in seven populations-three industrialized and four small-scale. Despite considerable variation in responses, we found that three of five main effects, and the two severity effects, exhibited statistically significant industrialized/ small-scale population differences. All differences could be explained as adaptive solutions to industrialized versus small-scale caretaking environments. Further, we found gradients in the relationship between the population-specific estimates and national-level socio-economic indicators, further implicating important aspects of the variation in industrialized and small-scale caretaking environments in shaping heuristics. Although there is mounting evidence for a genetic component to human maternal behaviour, there is no current evidence for interpopulation variation in candidate genes. We nonetheless suggest that heuristics guiding maternal behaviour in diverse societies emerge via convergent evolution in response to similar selective pressures.

Occurrence, elimination, enantiomeric distribution and intra-day variations of chiral pharmaceuticals in major wastewater treatment plants in Beijing, China.

PubMed

Duan, Lei; Zhang, Yizhe; Wang, Bin; Deng, Shubo; Huang, Jun; Wang, Yujue; Yu, Gang

2018-04-18

The occurrence, eliminations, enantiomeric distribution and intra-day variations of five chiral pharmaceuticals (three beta-blockers and two antidepressants) were investigated in eight major WWTPs in Beijing, China. The results revealed that metoprolol (MTP) and venlafaxine (VFX) were of the highest concentrations among the five determined pharmaceuticals with mean concentrations of 803 ng L -1 and 408 ng L -1 , respectively in influents, and 354 ng L -1 and 165 ng L -1 in effluents, respectively. Their removal efficiencies, intra-day concentration changes and enantiomeric profiles during wastewater treatment were further analyzed. Loads of these two chiral pharmaceuticals were also studied to reveal drug use pattern. A/A/O+MBR (anaerobic/anoxic/oxic + membrane bio-reactor) followed by joint disinfection treatment process exhibited the high removal efficiencies. No or weak enantioselectivity was observed in most WWTPs. However, obvious enantiomeric fraction (EF) changing of MTP was observed in WWTP3 employing A/A/O+MBR. Intra-day concentration fluctuations of MTP were smaller than VFX. A quick response to sudden rise influent concentration of MTP was observed in WWTP1 effluent but EF response lagged behind. Similar bihourly EF variations in influents and effluents were also observed in most WWTPs for MTP and VFX in consideration of hydraulic residence time (HRT). Copyright © 2018 Elsevier Ltd. All rights reserved.

Genome Size Variation in the Genus Carthamus (Asteraceae, Cardueae): Systematic Implications and Additive Changes During Allopolyploidization

PubMed Central

GARNATJE, TERESA; GARCIA, SÒNIA; VILATERSANA, ROSER; VALLÈS, JOAN

2006-01-01

• Background and Aims Plant genome size is an important biological characteristic, with relationships to systematics, ecology and distribution. Currently, there is no information regarding nuclear DNA content for any Carthamus species. In addition to improving the knowledge base, this research focuses on interspecific variation and its implications for the infrageneric classification of this genus. Genome size variation in the process of allopolyploid formation is also addressed. • Methods Nuclear DNA samples from 34 populations of 16 species of the genus Carthamus were assessed by flow cytometry using propidium iodide. • Key Results The 2C values ranged from 2·26 pg for C. leucocaulos to 7·46 pg for C. turkestanicus, and monoploid genome size (1Cx-value) ranged from 1·13 pg in C. leucocaulos to 1·53 pg in C. alexandrinus. Mean genome sizes differed significantly, based on sectional classification. Both allopolyploid species (C. creticus and C. turkestanicus) exhibited nuclear DNA contents in accordance with the sum of the putative parental C-values (in one case with a slight reduction, frequent in polyploids), supporting their hybrid origin. • Conclusions Genome size represents a useful tool in elucidating systematic relationships between closely related species. A considerable reduction in monoploid genome size, possibly due to the hybrid formation, is also reported within these taxa. PMID:16390843

The stress response and exploratory behaviour in Yucatan minipigs (Sus scrofa): Relations to sex and social rank.

PubMed

Adcock, Sarah J J; Martin, Gerard M; Walsh, Carolyn J

2015-12-01

According to the coping styles hypothesis, an individual demonstrates an integrated behavioural and physiological response to environmental challenge that is consistent over time and across situations. Individual consistency in behavioural responses to challenge has been documented across the animal kingdom. Comparatively few studies, however, have examined inter-individual variation in the physiological response, namely glucocorticoid and catecholamine levels, the stress hormones secreted by the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system, respectively. Variation in coping styles between individuals may be explained in part by differences in social rank and sex. Using 20 Yucatan minipigs (Sus scrofa) we: (1) investigated the existence of consistent inter-individual variation in exploratory behaviour and the hormonal stress response, and tested for correlations as predicted by the coping styles hypothesis; and (2) evaluated whether inter-individual behavioural and hormonal variation is related to social rank and sex. Salivary stress biomarkers (cortisol, alpha-amylase, chromogranin A) were assessed in the presence and absence of a stressor consisting of social isolation in a crate for 10 min. Principal components analysis on a set of behavioural variables revealed two traits, which we labelled exploratory tendency and neophobia. Neither exploratory tendency nor neophobia predicted the physiological stress response. Subordinate pigs exhibited higher catecholamine levels compared to dominant conspecifics. We observed sex differences in the repeatability of salivary stress markers and reactivity of the stress systems. The results do not provide support for the existence of behavioural-physiological coping styles in pigs. Sex is an important determinant of the physiological stress response and warrants consideration in research addressing behavioural and hormonal variation. Copyright © 2015 Elsevier Inc. All rights reserved.

Thermally Driven Photonic Actuator Based on Silica Opal Photonic Crystal with Liquid Crystal Elastomer.

PubMed

Xing, Huihui; Li, Jun; Shi, Yang; Guo, Jinbao; Wei, Jie

2016-04-13

We have developed a novel thermoresponsive photonic actuator based on three-dimensional SiO2 opal photonic crystals (PCs) together with liquid crystal elastomers (LCEs). In the process of fabrication of such a photonic actuator, the LCE precursor is infiltrated into the SiO2 opal PC followed by UV light-induced photopolymerization, thereby forming the SiO2 opal PC/LCE composite film with a bilayer structure. We find that this bilayer composite film simultaneously exhibits actuation behavior as well as the photonic band gap (PBG) response to external temperature variation. When the SiO2 opal PC/LCE composite film is heated, it exhibits a considerable bending deformation, and its PBG shifts to a shorter wavelength at the same time. In addition, this actuation is quite fast, reversible, and highly repeatable. The thermoresponsive behavior of the SiO2 opal PC/LCE composite films mainly derives from the thermal-driven change of nematic order of the LCE layer which leads to the asymmetric shrinkage/expansion of the bilayer structure. These results will be of interest in designing optical actuator systems for environment-temperature detection.

Assessment of Antioxidant Properties in Fruits of Myrica esculenta: A Popular Wild Edible Species in Indian Himalayan Region

PubMed Central

Rawat, Sandeep; Jugran, Arun; Giri, Lalit; Bhatt, Indra D.; Rawal, Ranbeer S.

2011-01-01

Crude extract of Myrica esculenta fruits, a wild edible species of Indian Himalayan Region, was evaluated for phenolic compounds and antioxidant properties. Results revealed significant variation in total phenolic and flavonoid contents across populations. Among populations, total phenolic content varied between 1.78 and 2.51 mg gallic acid equivalent/g fresh weight (fw) of fruits and total flavonoids ranged between 1.31 and 1.59 mg quercetin equivalent/g fw. Antioxidant activity determined by 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging, 1,1-diphenyl-2-picrylhydrazyl radical scavenging and ferric reducing antioxidant power (FRAP) exhibited considerable antioxidant potential and showed significant positive correlation with total phenolic and total flavonoids content. High performance liquid chromatography analysis revealed significant variation (P <  .01) in phenolic compounds (i.e., gallic acid, catechin, hydroxybenzioc acid and ρ-coumaric acid) across populations. This study provides evidences to establish that consumption of M. esculenta fruits while providing relished taste would also help in reduction of free radicals. Therefore, this wild edible species deserves promotion in the region through horticulture and forestry interventions. PMID:21785629

Machine Learning and Network Analysis of Molecular Dynamics Trajectories Reveal Two Chains of Red/Ox-specific Residue Interactions in Human Protein Disulfide Isomerase.

PubMed

Karamzadeh, Razieh; Karimi-Jafari, Mohammad Hossein; Sharifi-Zarchi, Ali; Chitsaz, Hamidreza; Salekdeh, Ghasem Hosseini; Moosavi-Movahedi, Ali Akbar

2017-06-16

The human protein disulfide isomerase (hPDI), is an essential four-domain multifunctional enzyme. As a result of disulfide shuffling in its terminal domains, hPDI exists in two oxidation states with different conformational preferences which are important for substrate binding and functional activities. Here, we address the redox-dependent conformational dynamics of hPDI through molecular dynamics (MD) simulations. Collective domain motions are identified by the principal component analysis of MD trajectories and redox-dependent opening-closing structure variations are highlighted on projected free energy landscapes. Then, important structural features that exhibit considerable differences in dynamics of redox states are extracted by statistical machine learning methods. Mapping the structural variations to time series of residue interaction networks also provides a holistic representation of the dynamical redox differences. With emphasizing on persistent long-lasting interactions, an approach is proposed that compiled these time series networks to a single dynamic residue interaction network (DRIN). Differential comparison of DRIN in oxidized and reduced states reveals chains of residue interactions that represent potential allosteric paths between catalytic and ligand binding sites of hPDI.

Evolutionary rates for multivariate traits: the role of selection and genetic variation

PubMed Central

Pitchers, William; Wolf, Jason B.; Tregenza, Tom; Hunt, John; Dworkin, Ian

2014-01-01

A fundamental question in evolutionary biology is the relative importance of selection and genetic architecture in determining evolutionary rates. Adaptive evolution can be described by the multivariate breeders' equation (), which predicts evolutionary change for a suite of phenotypic traits () as a product of directional selection acting on them (β) and the genetic variance–covariance matrix for those traits (G). Despite being empirically challenging to estimate, there are enough published estimates of G and β to allow for synthesis of general patterns across species. We use published estimates to test the hypotheses that there are systematic differences in the rate of evolution among trait types, and that these differences are, in part, due to genetic architecture. We find some evidence that sexually selected traits exhibit faster rates of evolution compared with life-history or morphological traits. This difference does not appear to be related to stronger selection on sexually selected traits. Using numerous proposed approaches to quantifying the shape, size and structure of G, we examine how these parameters relate to one another, and how they vary among taxonomic and trait groupings. Despite considerable variation, they do not explain the observed differences in evolutionary rates. PMID:25002697

Magnetic domains in Tb-Fe-Co thin films under anisotropy tilt

NASA Astrophysics Data System (ADS)

Talapatra, A.; Umadevi, K.; Arout Chelvane, J.; Mohanty, J.; Jayalakshmi, V.

2018-04-01

Tailoring of magnetic domains of Tb-Fe-Co thin films with rapid thermal processing has been reported in this paper. While the as-deposited films show elongated, inter-connected domains with high out-of-plane magnetic phase contrast, the rapid thermal processed films at 550 °C with different time intervals display deterioration of magnetic contrast. A longitudinal extension of domains has been observed with the processing time of 5 min. With subsequent increase in processing time, the domain patterns exhibit considerable decrease in magnetic phase difference combined with strong intermixing between two oppositely magnetized areas. The out-of-plane magnetic contrast is seen to be very weak for the Tb-Fe-Co film processed for 30 min. The domain morphology and the contrast variation have been modeled with micromagnetic simulations, considering the in-plane (along xz plane) tilt of anisotropy axis. The ground state energy profile and the variation in magnetic properties indicate the threshold tilt angle to be around 30 ° wherein the in-plane and out-of-plane squareness ratio and coercivities are comparable and hence the system shows a spin re-orientation behavior at higher tilt angles.

Sublethal effects of catch-and-release fishing: measuring capture stress, fish impairment, and predation risk using a condition index

USGS Publications Warehouse

Campbell, Matthew D.; Patino, Reynaldo; Tolan, J.M.; Strauss, R.E.; Diamond, S.

2009-01-01

The sublethal effects of simulated capture of red snapper (Lutjanus campechanus) were analysed using physiological responses, condition indexing, and performance variables. Simulated catch-and-release fishing included combinations of depth of capture and thermocline exposure reflective of environmental conditions experienced in the Gulf of Mexico. Frequency of occurrence of barotrauma and lack of reflex response exhibited considerable individual variation. When combined into a single condition or impairment index, individual variation was reduced, and impairment showed significant increases as depth increased and with the addition of thermocline exposure. Performance variables, such as burst swimming speed (BSS) and simulated predator approach distance (AD), were also significantly different by depth. BSSs and predator ADs decreased with increasing depth, were lowest immediately after release, and were affected for up to 15 min, with longer recovery times required as depth increased. The impairment score developed was positively correlated with cortisol concentration and negatively correlated with both BSS and simulated predator AD. The impairment index proved to be an efficient method to estimate the overall impairment of red snapper in the laboratory simulations of capture and shows promise for use in field conditions, to estimate release mortality and vulnerability to predation.

Shot sequencing based on biological equivalent dose considerations for multiple isocenter Gamma Knife radiosurgery.

PubMed

Ma, Lijun; Lee, Letitia; Barani, Igor; Hwang, Andrew; Fogh, Shannon; Nakamura, Jean; McDermott, Michael; Sneed, Penny; Larson, David A; Sahgal, Arjun

2011-11-21

Rapid delivery of multiple shots or isocenters is one of the hallmarks of Gamma Knife radiosurgery. In this study, we investigated whether the temporal order of shots delivered with Gamma Knife Perfexion would significantly influence the biological equivalent dose for complex multi-isocenter treatments. Twenty single-target cases were selected for analysis. For each case, 3D dose matrices of individual shots were extracted and single-fraction equivalent uniform dose (sEUD) values were determined for all possible shot delivery sequences, corresponding to different patterns of temporal dose delivery within the target. We found significant variations in the sEUD values among these sequences exceeding 15% for certain cases. However, the sequences for the actual treatment delivery were found to agree (<3%) and to correlate (R² = 0.98) excellently with the sequences yielding the maximum sEUD values for all studied cases. This result is applicable for both fast and slow growing tumors with α/β values of 2 to 20 according to the linear-quadratic model. In conclusion, despite large potential variations in different shot sequences for multi-isocenter Gamma Knife treatments, current clinical delivery sequences exhibited consistent biological target dosing that approached that maximally achievable for all studied cases.

Novel ratio difference at coabsorptive point spectrophotometric method for determination of components with wide variation in their absorptivities.

PubMed

Saad, Ahmed S; Abo-Talib, Nisreen F; El-Ghobashy, Mohamed R

2016-01-05

Different methods have been introduced to enhance selectivity of UV-spectrophotometry thus enabling accurate determination of co-formulated components, however mixtures whose components exhibit wide variation in absorptivities has been an obstacle against application of UV-spectrophotometry. The developed ratio difference at coabsorptive point method (RDC) represents a simple effective solution for the mentioned problem, where the additive property of light absorbance enabled the consideration of the two components as multiples of the lower absorptivity component at certain wavelength (coabsorptive point), at which their total concentration multiples could be determined, whereas the other component was selectively determined by applying the ratio difference method in a single step. Mixture of perindopril arginine (PA) and amlodipine besylate (AM) figures that problem, where the low absorptivity of PA relative to AM hinders selective spectrophotometric determination of PA. The developed method successfully determined both components in the overlapped region of their spectra with accuracy 99.39±1.60 and 100.51±1.21, for PA and AM, respectively. The method was validated as per the USP guidelines and showed no significant difference upon statistical comparison with reported chromatographic method. Copyright © 2015 Elsevier B.V. All rights reserved.

Community Composition and Abundance of Anammox Bacteria in Cattail Rhizosphere Sediments at Three Phenological Stages.

PubMed

Zhou, Xiaohong; Zhang, Jinping; Wen, Chunzi

2017-11-01

The distribution of anammox bacteria in rhizosphere sediments of cattail (Typha orientalis) at different phenological stages was investigated. Results showed that the number of 16S rRNA gene copies of the anammox bacteria was considerably higher in the rhizosphere sediment than in the nonrhizosphere sediment and control sediment. The abundances of the anammox bacteria exhibited striking temporal variations in the three different cattail phenological stages. In addition, the Chao1 and Shannon H indexes of the anammox bacteria in cattail rhizosphere sediments had evident spatial and temporal variations at different phenological stages. Four anammox genera (Brocadia, Kuenenia, Jettenia, and a new cluster) were detected and had proportions of 34.18, 45.57, 0.63, and 19.62%, respectively. The CCA analysis results indicated that Cu, TN, Pb, and Zn were pivotal factors that affect anammox bacteria composition. The PCoA analysis results indicated that the community structure at the rhizosphere and nonrhizosphere sediments collected on July was relatively specific and was different from sediments collected on other months, suggesting that cattail can influence the community structures of the anammox bacteria at the maturity stage.

Time-varying BRDFs.

PubMed

Sun, Bo; Sunkavalli, Kalyan; Ramamoorthi, Ravi; Belhumeur, Peter N; Nayar, Shree K

2007-01-01

The properties of virtually all real-world materials change with time, causing their bidirectional reflectance distribution functions (BRDFs) to be time varying. However, none of the existing BRDF models and databases take time variation into consideration; they represent the appearance of a material at a single time instance. In this paper, we address the acquisition, analysis, modeling, and rendering of a wide range of time-varying BRDFs (TVBRDFs). We have developed an acquisition system that is capable of sampling a material's BRDF at multiple time instances, with each time sample acquired within 36 sec. We have used this acquisition system to measure the BRDFs of a wide range of time-varying phenomena, which include the drying of various types of paints (watercolor, spray, and oil), the drying of wet rough surfaces (cement, plaster, and fabrics), the accumulation of dusts (household and joint compound) on surfaces, and the melting of materials (chocolate). Analytic BRDF functions are fit to these measurements and the model parameters' variations with time are analyzed. Each category exhibits interesting and sometimes nonintuitive parameter trends. These parameter trends are then used to develop analytic TVBRDF models. The analytic TVBRDF models enable us to apply effects such as paint drying and dust accumulation to arbitrary surfaces and novel materials.

Responses of infaunal populations to benthoscape structure and the potential importance of transition zones

USGS Publications Warehouse

Zajac, R.N.; Lewis, R.S.; Poppe, L.J.; Twichell, D.C.; Vozarik, J.; DiGiacomo-Cohen, M. L.

2003-01-01

Relationships between population abundance and seafloor landscape, or benthoscape, structure were examined for 16 infaunal taxa in eastern Long Island Sound. Based on analyses of a side-scan sonar mosaic, the 19.4-km2 study area was comprised of six distinct large-scale (> km2) benthoscape elements, with varying levels of mesoscale (km2-m2) and small-scale (2) physical and biological habitat heterogeneity. Transition zones among elements varied from ~50 to 200 m in width, comprised ~32% of the benthoscape, and added to overall benthoscape heterogeneity. Population abundances of nine taxa varied significantly among the large-scale elements. Most species were found at high abundances only in one benthoscape element, but three had several foci of elevated abundances. Analyses of population responses to habitat heterogeneity at different spatial scales indicated that abundances of eight taxa varied significantly among spatial scales, but the significant scales were mixed among these species. Relatively large residual variations suggest significant amounts of mesoscale spatial variation were unaccounted for, varying from ~1 km2 to several m2. Responses to transition zones were mixed as well. Abundances of nine taxa varied significantly among transition zones and interiors of benthoscape elements, most with elevated abundances in transition zones. Our results show that infaunal populations exhibit complex and spatially varying patterns of abundance in relation to benthoscape structure and suggest that mesoscale variation may be particularly critical in this regard. Also, transition zones among benthoscape features add considerably to this variation and may be ecological important areas in seafloor environments.

Geographic and phenotypic variation in heartwood and essential-oil characters in natural populations of Santalum austrocaledonicum in Vanuatu.

PubMed

Page, Tony; Southwell, Ian; Russell, Mike; Tate, Hanington; Tungon, Joseph; Sam, Chanel; Dickinson, Geoff; Robson, Ken; Leakey, Roger R B

2010-08-01

Phenotypic variation in heartwood and essential-oil characters of Santalum austrocaledonicum was assessed across eleven populations on seven islands of Vanuatu. Trees differed significantly in their percentage heartwood cross-sectional area and this varied independently of stem diameter. The concentrations of the four major essential-oil constituents (alpha-santalol, beta-santalol, (Z)-beta-curcumen-12-ol, and cis-nuciferol) of alcohol-extracted heartwood exhibited at least tenfold and continuous tree-to-tree variation. Commercially important components alpha- and beta-santalol found in individual trees ranged from 0.8-47% and 0-24.1%, respectively, across all populations, and significant (P<0.05) differences for each were found between individual populations. The Erromango population was unique in that the mean concentrations of its monocyclic ((Z)-beta-curcumen-12-ol and cis-nuciferol) sesquiterpenes exceeded those of its bi- and tricyclic (alpha- and beta-santalol) sesquiterpenes. Heartwood colour varied between trees and spanned 65 colour categories, but no identifiable relationships were found between heartwood colour and alpha- and beta-santalol, although a weak relationship was evident between colour saturation and total oil concentration. These results indicate that the heartwood colour is not a reliable predictive trait for oil quality. The results of this study highlight the knowledge gaps in fundamental understanding of heartwood biology in Santalum genus. The intraspecific variation in heartwood cross-sectional area, oil concentration, and oil quality traits is of considerable importance to the domestication of sandalwood and present opportunities for the development of highly superior S. austrocaledonicum cultivars that conform to the industry's International Standards used for S. album.

Maternal gestational androgens are associated with decreased juvenile play in white-faced marmosets (Callithrix geoffroyi)

PubMed Central

Birnie, Andrew K.; Hendricks, Shelton E.; Smith, Adam S.; Milam, Ross; French, Jeffrey A.

2013-01-01

Exposure to androgens during prenatal development shapes both physiological and behavioral developmental trajectories. Notably, in rhesus macaques, prenatal androgen exposure has been shown to increase rough-and-tumble play, a prominent behavioral feature in males during the juvenile period in primates. While macaques are an Old World, polygamous species with marked sexually dimorphic behavior, New World callitrichine primates (marmosets and tamarins) live in cooperative breeding groups and are considered to be socially monogamous and exhibit minimal sexual dimorphism in social play, which suggests that androgen may affect this species in different ways compared to macaques. In addition, we previously described considerable variation in maternal androgen production during gestation in marmosets. Here we tested the association between this variation and variation in offspring rough-and-tumble play patterns in both males and females. We measured testosterone and androstenedione levels in urine samples collected from pregnant marmoset mothers and then observed their offspring's play behavior as juveniles (5–10 months of age). In contrast to findings in rhesus macaques, hierarchical regression analyses showed that higher gestational testosterone levels, primarily in the second semester, were associated with decreased rough-and-tumble play in juveniles, and this relationship appears to be driven more so by males than females. We found no reliable associations between gestational androstenedione and juvenile play behavior. Our findings provide evidence to suggest that normative variation in levels of maternal androgen during gestation may influence developmental behavioral trajectories in marmosets in a way that contradicts previous findings in Old World primates. PMID:22705955

Isozyme variation in wild and cultivated pineapple

USDA-ARS?s Scientific Manuscript database

Isozyme variation was studied in 161 accessions of pineapple including four species of Ananas and one of Pseudananas. Six enzyme systems (ADH, GPI, PGM, SKDH, TPI, UGPP) involving seven putative loci revealed 35 electromorphs . Considerable variation exists within and between species of Ananas. Sixt...

Allozyme variation in spineless Pejibaye (Bactris gasipaes Kunth)

USDA-ARS?s Scientific Manuscript database

Isozyme variation was studied in 161 accessions of pineapple including four species of Ananas and one of Pseudananas. Six enzyme systems (ADH, GPI, PGM, SKDH, TPI, UGPP) involving seven putative loci revealed 35 electromorphs . Considerable variation exists within and between species of Ananas. Sixt...

Survey Shows Variation in Ph.D. Methods Training.

ERIC Educational Resources Information Center

Steeves, Leslie; And Others

1983-01-01

Reports on a 1982 survey of journalism graduate studies indicating considerable variation in research methods requirements and emphases in 23 universities offering doctoral degrees in mass communication. (HOD)

The evolution of floral nectaries in Disa (Orchidaceae: Disinae): recapitulation or diversifying innovation?

PubMed

Hobbhahn, Nina; Johnson, Steven D; Bytebier, Benny; Yeung, Edward C; Harder, Lawrence D

2013-11-01

The Orchidaceae have a history of recurring convergent evolution in floral function as nectar production has evolved repeatedly from an ancestral nectarless state. However, orchids exhibit considerable diversity in nectary type, position and morphology, indicating that this convergence arose from alternative adaptive solutions. Using the genus Disa, this study asks whether repeated evolution of floral nectaries involved recapitulation of the same nectary type or diversifying innovation. Epidermis morphology of closely related nectar-producing and nectarless species is also compared in order to identify histological changes that accompanied the gain or loss of nectar production. The micromorphology of nectaries and positionally equivalent tissues in nectarless species was examined with light and scanning electron microscopy. This information was subjected to phylogenetic analyses to reconstruct nectary evolution and compare characteristics of nectar-producing and nectarless species. Two nectary types evolved in Disa. Nectar exudation by modified stomata in floral spurs evolved twice, whereas exudation by a secretory epidermis evolved six times in different perianth segments. The spur epidermis of nectarless species exhibited considerable micromorphological variation, including strongly textured surfaces and non-secreting stomata in some species. Epidermis morphology of nectar-producing species did not differ consistently from that of rewardless species at the magnifications used in this study, suggesting that transitions from rewardlessness to nectar production are not necessarily accompanied by visible morphological changes but only require sub-cellular modification. Independent nectary evolution in Disa involved both repeated recapitulation of secretory epidermis, which is present in the sister genus Brownleea, and innovation of stomatal nectaries. These contrasting nectary types and positional diversity within types imply weak genetic, developmental or physiological constraints in ancestral, nectarless Disa. Such functional convergence generated by morphologically diverse solutions probably also underlies the extensive diversity of nectary types and positions in the Orchidaceae.

Fragmentation of care and the use of head computed tomography in patients with ischemic stroke.

PubMed

Bekelis, Kimon; Roberts, David W; Zhou, Weiping; Skinner, Jonathan S

2014-05-01

Computed tomographic (CT) scans are central diagnostic tests for ischemic stroke. Their inefficient use is a negative quality measure tracked by the Centers for Medicare and Medicaid Services. We performed a retrospective analysis of Medicare fee-for-service claims data for adults admitted for ischemic stroke from 2008 to 2009, with 1-year follow-up. The outcome measures were risk-adjusted rates of high-intensity CT use (≥4 head CT scans) and risk- and price-adjusted Medicare expenditures in the year after admission. The average number of head CT scans in the year after admission, for the 327 521 study patients, was 1.94, whereas 11.9% had ≥4. Risk-adjusted rates of high-intensity CT use ranged from 4.6% (Napa, CA) to 20.0% (East Long Island, NY). These rates were 2.6% higher for blacks than for whites (95% confidence interval, 2.1%-3.1%), with considerable regional variation. Higher fragmentation of care (number of different doctors seen) was associated with high-intensity CT use. Patients living in the top quintile regions of fragmentation experienced a 5.9% higher rate of high-intensity CT use, with the lowest quintile as reference; the corresponding odds ratio was 1.77 (95% confidence interval, 1.71-1.83). Similarly, 1-year risk- and price-adjusted expenditures exhibited considerable regional variation, ranging from $31 175 (Salem, MA) to $61 895 (McAllen, TX). Regional rates of high-intensity CT scans were positively associated with 1-year expenditures (r=0.56; P<0.01). Rates of high-intensity CT use for patients with ischemic stroke reflect wide practice patterns across regions and races. Medicare expenditures parallel these disparities. Fragmentation of care is associated with high-intensity CT use. © 2014 American Heart Association, Inc.

T-cell stimuli independently sum to regulate an inherited clonal division fate

PubMed Central

Marchingo, J. M.; Prevedello, G.; Kan, A.; Heinzel, S.; Hodgkin, P. D.; Duffy, K. R.

2016-01-01

In the presence of antigen and costimulation, T cells undergo a characteristic response of expansion, cessation and contraction. Previous studies have revealed that population-level reproducibility is a consequence of multiple clones exhibiting considerable disparity in burst size, highlighting the requirement for single-cell information in understanding T-cell fate regulation. Here we show that individual T-cell clones resulting from controlled stimulation in vitro are strongly lineage imprinted with highly correlated expansion fates. Progeny from clonal families cease dividing in the same or adjacent generations, with inter-clonal variation producing burst-size diversity. The effects of costimulatory signals on individual clones sum together with stochastic independence; therefore, the net effect across multiple clones produces consistent, but heterogeneous population responses. These data demonstrate that substantial clonal heterogeneity arises through differences in experience of clonal progenitors, either through stochastic antigen interaction or by differences in initial receptor sensitivities. PMID:27869196

Correlations Between Optical, Chemical and Physical Properties of Biomass Burn Aerosols

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

Hopkins, Rebecca J.; Lewis, Keith M.; Dessiaterik, Yury

2007-09-20

Single scattering albedo (ω) and Angstrom absorption coefficient (αap) values are measured at 405, 532 and 870 nm for aerosols generated during controlled laboratory combustion of twelve wildland fuels. Considerable fuel dependent variation in these optical properties is observed at these wavelengths. Complementary microspectroscopy techniques are used to elucidate spatially resolved local chemical bonding, carbon-to-oxygen atomic ratios, percent of sp2 hybridization (graphitic nature), elemental composition, particle size and morphology. These parameters are compared directly with the corresponding optical properties for each combustion product, facilitating an understanding of the fuel dependent variability observed. Results indicate that combustion products can be dividedmore » into three categories based on chemical, physical and optical properties. Only materials displaying a high degree of sp2 hybridization, with chemical and physical properties characteristic of ‘soot’ or black carbon, exhibit ω and αap values that indicate a high light absorbing capacity.« less

Effects of Uncertainty in TRMM Precipitation Radar Path Integrated Attenuation on Interannual Variations of Tropical Oceanic Rainfall

NASA Technical Reports Server (NTRS)

Robertson, Franklin R.; Fitzjarrald, Dan E.; Kummerow, Christian D.; Arnold, James E. (Technical Monitor)

2002-01-01

Considerable uncertainty surrounds the issue of whether precipitation over the tropical oceans (30 deg N/S) systematically changes with interannual sea-surface temperature (SST) anomalies that accompany El Nino (warm) and La Nina (cold) events. Time series of rainfall estimates from the Tropical Rainfall Measuring Mission (TRMM Precipitation Radar (PR) over the tropical oceans show marked differences with estimates from two TRMM Microwave Imager (TMI) passive microwave algorithms. We show that path-integrated attenuation derived from the effects of precipitation on the radar return from the ocean surface exhibits interannual variability that agrees closely with the TMI time series. Further analysis of the frequency distribution of PR (2A25 product) rain rates suggests that the algorithm incorporates the attenuation measurement in a very conservative fashion so as to optimize the instantaneous rain rates. Such an optimization appears to come at the expense of monitoring interannual climate variability.

Fatigue crack propagation behaviour of unidirectionally solidified gamma/gamma-prime-delta eutectic alloys. [Ni-Nb-Al alloys

NASA Technical Reports Server (NTRS)

Bretz, P. E.; Hertzberg, R. W.

1979-01-01

Fatigue crack propagation studies were carried out on unidirectionally solidified gamma/gamma-prime-delta (Ni-Nb-Al) alloys over an aluminum content range of 1.5-2.5% by weight. The variation of Al content of as-grown alloys did not significantly affect the crack growth behavior of these eutectic composites. The results indicate that the addition of Al to the eutectic dramatically improved the FCP behavior. The gamma/gamma-prime-delta alloy exhibited crack growth rates for a given stress intensity range that are an order of magnitude lower than those for the gamma-delta alloy. It is suggested that this difference in FCP behavior can be explained on the basis of stacking fault energy considerations. Extensive delaminations at the crack tip were also revealed, which contributed to the superior fatigue response. Delamination was predominantly intergranular in nature.

Smart responsive phosphorescent materials for data recording and security protection.

PubMed

Sun, Huibin; Liu, Shujuan; Lin, Wenpeng; Zhang, Kenneth Yin; Lv, Wen; Huang, Xiao; Huo, Fengwei; Yang, Huiran; Jenkins, Gareth; Zhao, Qiang; Huang, Wei

2014-04-07

Smart luminescent materials that are responsive to external stimuli have received considerable interest. Here we report ionic iridium (III) complexes simultaneously exhibiting mechanochromic, vapochromic and electrochromic phosphorescence. These complexes share the same phosphorescent iridium (III) cation with a N-H moiety in the N^N ligand and contain different anions, including hexafluorophosphate, tetrafluoroborate, iodide, bromide and chloride. The anionic counterions cause a variation in the emission colours of the complexes from yellow to green by forming hydrogen bonds with the N-H proton. The electronic effect of the N-H moiety is sensitive towards mechanical grinding, solvent vapour and electric field, resulting in mechanochromic, vapochromic and electrochromic phosphorescence. On the basis of these findings, we construct a data-recording device and demonstrate data encryption and decryption via fluorescence lifetime imaging and time-gated luminescence imaging techniques. Our results suggest that rationally designed phosphorescent complexes may be promising candidates for advanced data recording and security protection.

Shape-Dependent Skin Penetration of Silver Nanoparticles: Does It Really Matter?

PubMed Central

Tak, Yu Kyung; Pal, Sukdeb; Naoghare, Pravin K.; Rangasamy, Sabarinathan; Song, Joon Myong

2015-01-01

Advancements in nano-structured materials have facilitated several applications of nanoparticles (NPs). Skin penetration of NPs is a crucial factor for designing suitable topical antibacterial agents with low systemic toxicity. Available reports focus on size-dependent skin penetration of NPs, mainly through follicular pathways. Herein, for the first time, we demonstrate a proof-of-concept study that entails variations in skin permeability and diffusion coefficients, penetration rates and depth-of-penetration of differently shaped silver NPs (AgNPs) via intercellular pathways using both in vitro and in vivo models. The antimicrobial activity of AgNPs is known. Different shapes of AgNPs may exhibit diverse antimicrobial activities and skin penetration capabilities depending upon their active metallic facets. Consideration of the shape dependency of AgNPs in antimicrobial formulations could help developing an ideal topical agent with the highest efficacy and low systemic toxicity. PMID:26584777

Microwave heating effects on the chemical composition and the antioxidant capacity of tataouine virgin olive oils from Tunisia.

PubMed

Oueslati, Imen; Taamalli, Wael; Haddada, Faouzia M; Zarrouk, Mokhtar

2010-10-01

Four Tunisian virgin olive oils (VOOs), derived from varieties (Chemlali Tataouine, Zarrazi Douirat, Fakhari Douirat, and Dhokar Douirat) grown in the harsh pedoclimatic conditions of the region of Tataouine, were evaluated for their responses to microwave heating. Aside from fatty acid composition, all other evaluated parameters were affected by microwave heating, and their variations depend on the genetic factor. Chemlali Tataouine VOO exhibited the slowest biophenol degradation rate and the least diminution in oxidative stability and consequently, its total fraction and both lipidic and methanolic fractions remained unchanged with an exceptional antioxidant potential. In the remaining studied VOOs, the biophenol contents, the oxidative stability, and the antioxidant potential underwent gradual decreases; nevertheless, their levels at the longer treatment time are close to some fresh VOOs. These results should be taken into consideration when Tataouine VOOs are recommended for microwave heating.

Evaluation of feed grade sodium bisulfate impact on gastrointestinal tract microbiota ecology in broilers via a pyrosequencing platform.

PubMed

Park, Si Hong; Dowd, Scot E; McReynolds, Jack L; Byrd, James A; Nisbet, David J; Ricke, Steven C

2015-12-01

The gastrointestinal microbial community in broiler chickens consists of many different species of bacteria, and the overall microbiota can vary from bird to bird. To control pathogenic bacteria in broilers and improve gut health, numerous potential dietary amendments have been used. In this study, we used a pyrosequencing platform to evaluate the effect of sodium bisulfate on microbiota of the crop, cecum, and ileum of broiler chickens grown over several weeks. The diversity information in each digestive organ sample exhibited considerable variation and was clearly separable, suggesting distinct bacterial populations. Although no apparent microbial clustering occurred between the control and the dietary treatments, we did observe shifts in overall microbiota populations in the crop, ileum, and ceca as well as changes in specific microorganisms such as Bacteroides, Clostridium, and Lactobacillus species that were identified as birds became older. © 2015 Poultry Science Association Inc.

Uncertainty analysis and global sensitivity analysis of techno-economic assessments for biodiesel production.

PubMed

Tang, Zhang-Chun; Zhenzhou, Lu; Zhiwen, Liu; Ningcong, Xiao

2015-01-01

There are various uncertain parameters in the techno-economic assessments (TEAs) of biodiesel production, including capital cost, interest rate, feedstock price, maintenance rate, biodiesel conversion efficiency, glycerol price and operating cost. However, fewer studies focus on the influence of these parameters on TEAs. This paper investigated the effects of these parameters on the life cycle cost (LCC) and the unit cost (UC) in the TEAs of biodiesel production. The results show that LCC and UC exhibit variations when involving uncertain parameters. Based on the uncertainty analysis, three global sensitivity analysis (GSA) methods are utilized to quantify the contribution of an individual uncertain parameter to LCC and UC. The GSA results reveal that the feedstock price and the interest rate produce considerable effects on the TEAs. These results can provide a useful guide for entrepreneurs when they plan plants. Copyright © 2014 Elsevier Ltd. All rights reserved.

Epigenetic Contribution of the Myosin Light Chain Kinase Gene to the Risk for Acute Respiratory Distress Syndrome

PubMed Central

Szilágyi, Keely L.; Liu, Cong; Zhang, Xu; Wang, Ting; Fortman, Jeffrey D.; Zhang, Wei; Garcia, Joe G.N.

2016-01-01

Acute respiratory distress syndrome (ARDS) is a devastating clinical syndrome with a considerable case fatality rate (~30-40%). Health disparities exist with African descent subjects (ADs) exhibiting greater mortality than European descent individuals (EDs). Myosin light chain kinase (MLCK) is encoded by MYLK whose genetic variants are implicated in ARDS pathogenesis and may influence ARDS mortality. As baseline population-specific epigenetic changes, i.e. cytosine modifications, have been observed between AD and ED individuals, epigenetic variations in MYLK may provide insights into ARDS disparities. We compared methylation levels of MYLK CpGs between ARDS patients and ICU controls overall and by ethnicity in a nested case control study of 39 ARDS cases and 75 non-ARDS intensive care unit controls. Two MYLK CpG sites (cg03892735, cg23344121) were differentially modified between ARDS subjects and controls (p<0.05; q<0.25) in a logistic regression model, where no effect modification from ethnicity or age was found. One CpG site was associated with ARDS in patients less than 58 years old, cg19611163 (intron 19,20). Two CpG sites were associated with ARDS in EDs only, gene body CpG (cg01894985, intron 2,3) and CpG (cg16212219, intron 31,32), with higher modification levels exhibited in ARDS subjects than controls. Cis-acting mQTL (modified cytosine quantitative trait loci) were identified using linear regression between local genetic variants and modification levels for two ARDS-associated CpGs (cg23344121, cg16212219). In summary, these ARDS-associated MYLK CpGs with effect modification by ethnicity and local mQTL, suggest that MYLK epigenetic variation and local genetic background may contribute to health disparities observed in ARDS. PMID:27543902

Environment, Migratory Tendency, Phylogeny and Basal Metabolic Rate in Birds

PubMed Central

Jetz, Walter; Freckleton, Robert P.; McKechnie, Andrew E.

2008-01-01

Basal metabolic rate (BMR) represents the minimum maintenance energy requirement of an endotherm and has far-reaching consequences for interactions between animals and their environments. Avian BMR exhibits considerable variation that is independent of body mass. Some long-distance migrants have been found to exhibit particularly high BMR, traditionally interpreted as being related to the energetic demands of long-distance migration. Here we use a global dataset to evaluate differences in BMR between migrants and non-migrants, and to examine the effects of environmental variables. The BMR of migrant species is significantly higher than that of non-migrants. Intriguingly, while the elevated BMR of migrants on their breeding grounds may reflect the metabolic machinery required for long-distance movements, an alternative (and statistically stronger) explanation is their occupation of predominantly cold high-latitude breeding areas. Among several environmental predictors, average annual temperature has the strongest effect on BMR, with a 50% reduction associated with a 20°C gradient. The negative effects of temperature variables on BMR hold separately for migrants and non-migrants and are not due their different climatic associations. BMR in migrants shows a much lower degree of phylogenetic inertia. Our findings indicate that migratory tendency need not necessarily be invoked to explain the higher BMR of migrants. A weaker phylogenetic signal observed in migrants supports the notion of strong phenotypic flexibility in this group which facilitates migration-related BMR adjustments that occur above and beyond environmental conditions. In contrast to the findings of previous analyses of mammalian BMR, primary productivity, aridity or precipitation variability do not appear to be important environmental correlates of avian BMR. The strong effects of temperature-related variables and varying phylogenetic effects reiterate the importance of addressing both broad-scale and individual-scale variation for understanding the determinants of BMR. PMID:18810267

Environmental drivers and reproductive consequences of variation in the diet of a marine predator

NASA Astrophysics Data System (ADS)

Gladics, Amanda J.; Suryan, Robert M.; Parrish, Julia K.; Horton, Cheryl A.; Daly, Elizabeth A.; Peterson, William T.

2015-06-01

Ocean conditions can greatly impact lower trophic level prey assemblages in marine ecosystems, with effects of ocean state propagating to higher trophic levels. In many regions throughout their range, common murre (Uria aalge) exhibit narrow dietary breadth in feeding chicks and therefore are vulnerable to recruitment failures of dominant prey species during the breeding season. Contrastingly, common murres nesting in the northern California Current off Oregon, exhibit high species diversity and variability in dominant prey consumed. We studied the diets of common murres over 10 years between 1998 and 2011, a period in which the northern California Current experienced dramatic interannual variability in ocean conditions. Likewise, murre diets off Oregon varied considerably. Interannual variation in murre chick diets was influenced by environmental drivers occurring before and during the breeding season, and at both basin and local scales. While clupeids (likely Pacific herring, Clupea pallasii) were an important diet component throughout the study period, in some years murre diets were dominated by Pacific sand lance (Ammodytes hexapterus) and in other years by osmerids (likely whitebait smelt, Allosmerus elongatus and surf smelt, Hypomesus pretiosus). Years in which the Pacific Decadal Oscillation and local sea surface temperatures were higher during summer also showed elevated levels of clupeids in murre diets, while years with higher North Pacific Gyre Oscillation index values and greater local winter ichthyoplankton biomass had fewer clupeids and more sand lance or smelts. Years with higher values of the Northern Oscillation Index during summer and an earlier spring transition showed higher proportion of smelts in the diets. Nesting phenology and reproductive success were negatively correlated with gradients in sand lance and clupeids, respectively, reflecting demographic consequences of environmental variability mediated through bottom-up food web dynamics.

Why is seed production so variable among individuals? A ten-year study with oaks reveals the importance of soil environment.

PubMed

Pérez-Ramos, Ignacio M; Aponte, Cristina; García, Luis V; Padilla-Díaz, Carmen M; Marañón, Teodoro

2014-01-01

Mast-seeding species exhibit not only a large inter-annual variability in seed production but also considerable variability among individuals within the same year. However, very little is known about the causes and consequences for population dynamics of this potentially large between-individual variability. Here, we quantified seed production over ten consecutive years in two Mediterranean oak species - the deciduous Quercus canariensis and the evergreen Q. suber - that coexist in forests of southern Spain. First, we calibrated likelihood models to identify which abiotic and biotic variables best explain the magnitude (hereafter seed productivity) and temporal variation of seed production at the individual level (hereafter CVi), and infer whether reproductive effort results from the available soil resources for the plant or is primarily determined by selectively favoured strategies. Second, we explored the contribution of between-individual variability in seed production as a potential mechanism of satiation for predispersal seed predators. We found that Q. canariensis trees inhabiting moister and more fertile soils were more productive than those growing in more resource-limited sites. Regarding temporal variation, individuals of the two studied oak species inhabiting these resource-rich environments also exhibited larger values of CVi. Interestingly, we detected a satiating effect on granivorous insects at the tree level in Q. suber, which was evident in those years where between-individual variability in acorn production was higher. These findings suggest that individual seed production (both in terms of seed productivity and inter-annual variability) is strongly dependent on soil resource heterogeneity (at least for one of the two studied oak species) with potential repercussions for recruitment and population dynamics. However, other external factors (such as soil heterogeneity in pathogen abundance) or certain inherent characteristics of the tree might be also involved in this process.

In situ cardiac perfusion reveals interspecific variation of intraventricular flow separation in reptiles.

PubMed

Joyce, William; Axelsson, Michael; Altimiras, Jordi; Wang, Tobias

2016-07-15

The ventricles of non-crocodilian reptiles are incompletely divided and provide an opportunity for mixing of oxygen-poor blood and oxygen-rich blood (intracardiac shunting). However, both cardiac morphology and in vivo shunting patterns exhibit considerable interspecific variation within reptiles. In the present study, we develop an in situ double-perfused heart approach to characterise the propensity and capacity for shunting in five reptile species: the turtle Trachemys scripta, the rock python Python sebae, the yellow anaconda Eunectes notaeus, the varanid lizard Varanus exanthematicus and the bearded dragon Pogona vitticeps To simulate changes in vascular bed resistance, pulmonary and systemic afterloads were independently manipulated and changes in blood flow distribution amongst the central outflow tracts were monitored. As previously demonstrated in Burmese pythons, rock pythons and varanid lizards exhibited pronounced intraventricular flow separation. As pulmonary or systemic afterload was raised, flow in the respective circulation decreased. However, flow in the other circulation, where afterload was constant, remained stable. This correlates with the convergent evolution of intraventricular pressure separation and the large intraventricular muscular ridge, which compartmentalises the ventricle, in these species. Conversely, in the three other species, the pulmonary and systemic flows were strongly mutually dependent, such that the decrease in pulmonary flow in response to elevated pulmonary afterload resulted in redistribution of perfusate to the systemic circuit (and vice versa). Thus, in these species, the muscular ridge appeared labile and blood could readily transverse the intraventricular cava. We conclude that relatively minor structural differences between non-crocodilian reptiles result in the fundamental changes in cardiac function. Further, our study emphasises that functionally similar intracardiac flow separation evolved independently in lizards (varanids) and snakes (pythons) from an ancestor endowed with the capacity for large intracardiac shunts. © 2016. Published by The Company of Biologists Ltd.

Two Y-chromosome-specific restriction fragment length polymorphisms (DYS11 and DYZ8) in Italian and Greek migrants to Australia.

PubMed

Mitchell, R J; Earl, L; Williams, J W

1993-06-01

The part of the Y chromosome not involved in recombination has been found to exhibit an extremely low frequency of DNA restriction fragment length polymorphisms (RFLPs) compared with either the X chromosome or autosomes. Also, the few Y-chromosome-specific RFLPs that have been identified have rarely been examined in more than one population. In this study two Y-chromosome-specific RFLPs at loci DYS11 and DYZ8 are examined in Italian and Greek migrants to Australia. The frequency of the rarer (8.5-kb) TaqI allele at DYS11 was 21% in Italians and even greater (34%) in Greeks. There is an inverse relationship between the frequency of the 8.5-kb allele and latitude on the Italian mainland; the regional variation (based on subject's birthplace in Italy) was significant (p < 0.01). The incidence of the 8.5-kb allele in southern Italy may reflect Greek colonization during pre-Roman times when this region was part of Magna Graecia. The frequency of the variant TaqI allele (7, 4 kb) at the DYZ8 locus is much higher in both Greeks and Italians (31% in each) than in Germans (5%), the only previously examined population. DYZ8 shows considerably less variation than DYS11 across the regional divisions of both Greece and Italy. The present findings, when added to the few other data available, indicate that these two Y-chromosome-specific loci are useful markers for investigating population affinities through the paternal line. Also, heterogeneity at these two loci (and added to that at the DYS1 locus) suggests that Mediterranean populations, compared with other groups, exhibit a high level of diversity of Y-chromosome-specific RFLPs.

Population-Based Resequencing of Experimentally Evolved Populations Reveals the Genetic Basis of Body Size Variation in Drosophila melanogaster

PubMed Central

Turner, Thomas L.; Stewart, Andrew D.; Fields, Andrew T.; Rice, William R.; Tarone, Aaron M.

2011-01-01

Body size is a classic quantitative trait with evolutionarily significant variation within many species. Locating the alleles responsible for this variation would help understand the maintenance of variation in body size in particular, as well as quantitative traits in general. However, successful genome-wide association of genotype and phenotype may require very large sample sizes if alleles have low population frequencies or modest effects. As a complementary approach, we propose that population-based resequencing of experimentally evolved populations allows for considerable power to map functional variation. Here, we use this technique to investigate the genetic basis of natural variation in body size in Drosophila melanogaster. Significant differentiation of hundreds of loci in replicate selection populations supports the hypothesis that the genetic basis of body size variation is very polygenic in D. melanogaster. Significantly differentiated variants are limited to single genes at some loci, allowing precise hypotheses to be formed regarding causal polymorphisms, while other significant regions are large and contain many genes. By using significantly associated polymorphisms as a priori candidates in follow-up studies, these data are expected to provide considerable power to determine the genetic basis of natural variation in body size. PMID:21437274

Genetic variation affecting host-parasite interactions: different genes affect different aspects of sigma virus replication and transmission in Drosophila melanogaster.

PubMed

Bangham, Jenny; Kim, Kang-Wook; Webster, Claire L; Jiggins, Francis M

2008-04-01

In natural populations, genetic variation affects resistance to disease. Knowing how much variation exists, and understanding the genetic architecture of this variation, is important for medicine, for agriculture, and for understanding evolutionary processes. To investigate the extent and nature of genetic variation affecting resistance to pathogens, we are studying a tractable model system: Drosophila melanogaster and its natural pathogen the vertically transmitted sigma virus. We show that considerable genetic variation affects transmission of the virus from parent to offspring. However, maternal and paternal transmission of the virus is affected by different genes. Maternal transmission is a simple Mendelian trait: most of the genetic variation is explained by a polymorphism in ref(2)P, a gene already well known to affect resistance to sigma. In contrast, there is considerable genetic variation in paternal transmission that cannot be explained by ref(2)P and is caused by other loci on chromosome 2. Furthermore, we found no genetic correlation between paternal transmission of the virus and resistance to infection by the sigma virus following injection. This suggests that different loci affect viral replication and paternal transmission.

Naturally occurring variation in tadpole morphology and performance linked to predator regime

Treesearch

James B. Johnson; Daniel Saenz; Cory K. Adams; Toby J. Hibbitts

2015-01-01

Divergent natural selection drives a considerable amount of the phenotypic and genetic variation observed in natural populations. For example, variation in the predator community can generate conflicting selection on behavioral, life-history, morphological, and performance traits. Differences in predator regime can subsequently increase phenotypic and genetic...

Genetic differentiation among populations of marine algae

NASA Astrophysics Data System (ADS)

Innes, D. J.

1984-09-01

Most of the information for genetic differentiation among populations of marine algae is from studies on ecotypic variation. Physiological ecotypes have been described for individuals showing different responses to temperature and salinity conditions. Morphological ecotypes have also been found associated with areas differing in wave exposure or different intertidal positions. Little is known on how genetic variation is organized within and between populations of marine algae. The occurrence of ecotypic variation in some species is evidence for genetic differentiation among populations resulting from selection by the local environment. The rate of dispersal and subsequent gene flow will also affect the level of differentiation among populations. In species with low dispersal, differentiation can arise through chance founder events or random genetic drift. The few studies available have shown that species of algae exhibit a range of dispersal capabilities. This information can be useful for predicting the potential level of genetic differentiation among populations of these species. Crossing experiments with several species of algae have shown that populations separated by a considerable distance can be interfertile. In some cases individuals from these populations have been found to be morphologically distinct. Crosses have been used to study the genetic basis of this variation and are evidence for genetic differentiation among the populations sampled. Genetic variation of enzyme proteins detected by electrophoresis provides an additional method for measuring genetic variation within and between populations of marine algae. Electrophoretic methods have previously been used to study systematic problems in algae. However, there have been few attempts to use electrophoretic variation to study the genetic structure of populations of marine algae. This approach is outlined and includes some of the potential problems associated with interpreting electrophoretic data. Studies of electrophoretic variation in natural populations of Enteromorpha linza from Long island Sound are used as an example. This species was found to reproduce only asexually. Despite a dispersing spore stage, genetic differentiation was found on a microgeographic scale and was correlated with differences in the local environment of some of the populations. Similar studies on other species, and especially sexually reproducing species, will add to a growing understanding of the evolutionary genetics of marine algae.

Variations in biochemical values for common laboratory tests: a comparison among multi-ethnic Israeli women cohort.

PubMed

Birk, Ruth; Heifetz, Eliyahu M

2018-04-28

Biochemical laboratory values are an essential tool in medical diagnosis, treatment, and follow-up; however, they are known to vary between populations. Establishment of ethnicity-adjusted reference values is recommended by health organizations. To investigate the ethnicity element in biochemical lab values studying women of different ethnic groups. Biochemical lab values (n = 27) of 503 adult Israeli women of three ethnicities (Jewish Ashkenazi, Jewish Sephardic, and Bedouin Arab) attending a single medical center were analyzed. Biochemical data were extracted from medical center records. Ethnic differences of laboratory biochemicals were studied using ANCOVA to analyze the center of the distribution as well as quartile regression analysis to analyze the upper and lower limits, both done with an adjustment for age. Significant ethnic differences were found in almost half (n = 12) of the biochemical laboratory tests. Ashkenazi Jews exhibited significantly higher mean values compared to Bedouins in most of the biochemical tests, including albumin, alkaline phosphatase, calcium, cholesterol, cholesterol LDL and HDL, cholesterol LDL calc., folic acid, globulin, and iron saturation, while the Bedouins exhibited the highest mean values in the creatinine and triglycerides. For most of these tests, Sephardic Jews exhibited biochemical mean levels in between the two other groups. Compared to Ashkenazi Jews, Sephardic Jews had a significant shift to lower values in cholesterol LDL. Ethnic subpopulations have distinct distributions in biochemical laboratory test values, which should be taken into consideration in medical practice enabling precision medicine.

Effects of variation in coagulation and photochemistry parameters on the particle size distributions in the Venus clouds

NASA Astrophysics Data System (ADS)

McGouldrick, Kevin

2017-12-01

This paper explores the effects that variation in the coalescence efficiency of the Venus cloud particles can have on the structure of the Venus cloud. It is motivated by the acknowledgment of uncertainties in the measured parameters—and the assumptions made to account for them—that define our present knowledge of the particle characteristics. Specifically, we explore the consequence of allowing the coalescence efficiency of supercooled sulfuric acid in the upper clouds to tend to zero. This produces a cloud that occasionally exhibits an enhancement of small particles at altitude (similar to the upper hazes observed by Pioneer Venus and subsequently shown to be somewhat transient). This simulated cloud occasionally exhibits a rapid growth of particle size near cloud base, exhibiting characteristics similar to those seen in the controversial Mode 3 particles. These results demonstrate that a subset of the variations observed as near-infrared opacity variations in the lower and middle clouds of Venus can be explained by microphysical, in addition to dynamical, variations. Furthermore, the existence of a population of particles exhibiting less efficient coalescence efficiencies would support the likelihood of conditions suitable for charge exchange, hence lightning, in the Venus clouds. We recommend future laboratory studies on the coalescence properties of sulfuric acid under the range of conditions experienced in the Venus clouds. We also recommend future in situ measurements to better characterize the properties of the cloud particles themselves, especially composition and particle habits (shapes).[Figure not available: see fulltext.

Variation in tooth morphology of Gorilla gorilla.

PubMed

Uchida, A

1998-01-01

Gorilla gorilla exemplifies a species that shows considerable variation in habitat, behaviour, genetic structure and morphology. This study examines variation of dental morphology in gorillas. Despite the marked size dimorphism, there are no significant shape differences between the sexes within subspecies. Differences in dental morphology, including tooth cusp proportions between the western G. g. gorilla and the eastern G. g. beringei are considerable. Although more similar to G. g. beringei than to the western G. g. gorilla, G. g. graueri also shows distinct morphological features. This indicates that the morphology of G. g. graueri is not merely intermediate, and genetic isolation between the two eastern subspecies could have had a substantial influence. Such extensive variation in dental morphology in Gorilla gorilla can be considered to be the result of an interesting combination of factors, including local dietary adaptations.

A dipole pattern of summertime rainfall across the Indian subcontinent and the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Jiang, X.; Ting, M.

2017-12-01

The Tibetan Plateau (TP) has long been regarded as a key driver for the formation and variations of the Indian summer monsoon (ISM). Recent studies, however, indicated that the ISM also exerts a considerable impact on rainfall variations in the TP, suggesting that the ISM and the TP should be considered as an interactive system. From this perspective, we investigate the co-variability of the July-August mean rainfall across the Indian subcontinent (IS) and the TP. We found that the interannual variation of IS and TP rainfall exhibits a dipole pattern in which rainfall in the central and northern IS tends to be out of phase with that in the southeastern TP. This dipole pattern is associated with significant anomalies in rainfall, atmospheric circulation, and water vapor transport over the Asian continent and nearby oceans. Rainfall anomalies and the associated latent heating in the central and northern IS tend to induce changes in regional circulation -that suppress rainfall in the southeastern TP and vice versa. Furthermore, the sea surface temperature anomalies in the tropical southeastern Indian Ocean can trigger the dipole rainfall pattern by suppressing convection over the central IS and the northern Bay of Bengal, which further induces anomalous anticyclonic circulation to the south of TP that favors more rainfall in the southeastern TP by transporting more water vapor to the region. The dipole pattern is also linked to the Silk-Road wave train due to its link to rainfall over the northwestern IS.

Repression of P Element-Mediated Hybrid Dysgenesis in Drosophila Melanogaster

PubMed Central

Simmons, M. J.; Raymond, J. D.; Rasmusson, K. E.; Miller, L. M.; McLarnon, C. F.; Zunt, J. R.

1990-01-01

Inbred lines derived from a strain called Sexi were analyzed for their abilities to repress P element-mediated gonadal dysgenesis. One line had high repression ability, four had intermediate ability and two had very low ability. The four intermediate lines also exhibited considerable within-line variation for this trait; furthermore, in at least two cases, this variation could not be attributed to recurring P element movement. Repression of gonadal dysgenesis in the hybrid offspring of all seven lines was due primarily to a maternal effect; there was no evidence for repression arising de novo in the hybrids themselves. In one of the lines, repression ability was inherited maternally, indicating the involvement of cytoplasmic factors. In three other lines, repression ability appeared to be determined by partially dominant or additive chromosomal factors; however, there was also evidence for a maternal effect that reduced the expression of these factors in at least two of the lines. In another line, repression ability seemed to be due to recessive chromosomal factors. All seven lines possessed numerous copies of a particular P element, called KP, which has been hypothesized to produce a polypeptide repressor of gonadal dysgenesis. This hypothesis, however, does not explain why the inbred Sexi lines varied so much in their repression abilities. It is suggested that some of this variation may be due to differences in the chromosomal position of the KP elements, or that other nonautonomous P elements are involved in the repression of hybrid dysgenesis in these lines. PMID:2155854

Morphometric variation in the papionin muzzle and the biochronology of the South African Plio-Pleistocene karst cave deposits.

PubMed

Gilbert, Christopher C; Grine, Frederick E

2010-03-01

Papionin monkeys are widespread, relatively common members of Plio-Pleistocene faunal assemblages across Africa. For these reasons, papionin taxa have been used as biochronological indicators by which to infer the ages of the South African karst cave deposits. A recent morphometric study of South African fossil papionin muzzle shape concluded that its variation attests to a substantial and greater time depth for these sites than is generally estimated. This inference is significant, because accurate dating of the South African cave sites is critical to our knowledge of hominin evolution and mammalian biogeographic history. We here report the results of a comparative analysis of extant papionin monkeys by which variability of the South African fossil papionins may be assessed. The muzzles of 106 specimens representing six extant papionin genera were digitized and interlandmark distances were calculated. Results demonstrate that the overall amount of morphological variation present within the fossil assemblage fits comfortably within the range exhibited by the extant sample. We also performed a statistical experiment to assess the limitations imposed by small sample sizes, such as typically encountered in the fossil record. Results suggest that 15 specimens are sufficient to accurately represent the population mean for a given phenotype, but small sample sizes are insufficient to permit the accurate estimation of the population standard deviation, variance, and range. The suggestion that the muzzle morphology of fossil papionins attests to a considerable and previously unrecognized temporal depth of the South African karst cave sites is unwarranted.

Creating Library Interiors: Planning and Design Considerations.

ERIC Educational Resources Information Center

Jones, Plummer Alston, Jr.; Barton, Phillip K.

1997-01-01

Examines design considerations for public library interiors: access; acoustical treatment; assignable and nonassignable space; building interiors: ceilings, clocks, color, control, drinking fountains; exhibit space: slotwall display, floor coverings, floor loading, furniture, lighting, mechanical systems, public address, copying machines,…

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

Skordas, E. S., E-mail: eskordas@phys.uoa.gr

By applying Detrended Fluctuation Analysis (DFA) to the time series of the geomagnetic data recorded at three measuring stations in Japan, Rong et al. in 2012 recently reported that anomalous magnetic field variations were identified well before the occurrence of the disastrous Tohoku M{sub w}9.0 earthquake that occurred on 11 March 2011 in Japan exhibiting increased “non-uniform” scaling behavior. Here, we provide an explanation for the appearance of this increase of “non-uniform” scaling on the following grounds: These magnetic field variations are the ones that accompany the electric field variations termed Seismic Electric Signals (SES) activity which have been repeatedlymore » reported that precede major earthquakes. DFA as well as multifractal DFA reveal that the latter electric field variations exhibit scaling behavior as shown by analyzing SES activities observed before major earthquakes in Greece. Hence, when these variations are superimposed on a background of pseudosinusoidal trend, their long range correlation properties—quantified by DFA—are affected resulting in an increase of the “non-uniform” scaling behavior. The same is expected to hold for the former magnetic field variations. This explanation is strengthened by recent findings showing that the fluctuations of the order parameter of seismicity exhibited an unprecedented minimum almost two months before the Tohoku earthquake occurrence which is characteristic for an almost simultaneous emission of Seismic Electric Signals activity.« less

Interpreting species-specific variation in tree-ring oxygen isotope ratios among three temperate forest trees

Treesearch

Xin Song; Kenneth S. Clark; Brent R. Helliker

2014-01-01

Although considerable variation has been documented in tree-ring cellulose oxygen isotope ratios (δ18Ocell) among co-occurring species, the underlying causes are unknown. Here, we used a combination of field measurements and modelling to investigate the mechanisms behind variations in late-wood δ

MUSE observations of M87: radial gradients for the stellar initial-mass function and the abundance of Sodium

NASA Astrophysics Data System (ADS)

Sarzi, Marc; Spiniello, Chiara; Barbera, Francesco La; Krajnović, Davor; Bosch, Remco van den

2018-05-01

Based on MUSE integral-field data we present evidence for a radial variation at the low-mass end of the stellar initial-mass function (IMF) in the central regions of the giant early-type galaxy NGC 4486 (M87). We used state-of-the-art stellar population models and the observed strength of various IMF-sensitive absorption-line features to solve for the best low-mass tapered "bimodal" form of the IMF, while accounting also for variations in stellar metallicity, the overall α-elements abundance and the abundance of individual elements such as Ti, O, Na and Ca. Our analysis reveals a strong negative IMF gradient corresponding to an exceeding fraction of low-mass stars compared to the case of the Milky Way toward the center of M87, which drops to nearly Milky-way levels by 0.4 Re. Such IMF variations correspond to over a factor two increase in stellar mass-to-light M/L ratio compared to the case of a Milky-way IMF, consistent with independent constraints on M/L radial variations in M87 from dynamical models. We also looked into the abundance of Sodium in M87, which turned up to be super-Solar over the entire radial range of our MUSE observations and to exhibit a considerable negative gradient. These findings suggest an additional role of metallicity in boosting the Na-yields in the central, metal-rich regions of M87 during its early and brief star-formation history. Our work adds M87 to the few objects that presently have radial constraints on their IMF or [Na/Fe] abundance, while also illustrating the accuracy that MUSE could bring to this kind of investigations.

The role of sexual selection and conflict in mediating among-population variation in mating strategies and sexually dimorphic traits in Sepsis punctum.

PubMed

Dmitriew, Caitlin; Blanckenhorn, Wolf U

2012-01-01

The black scavenger fly Sepsis punctum exhibits striking among-population variation in the direction and magnitude of sexual size dimorphism, modification to the male forelimb and pre-copulatory behaviour. In some populations, male-biased sexual size dimorphism is observed; in other, less dimorphic, populations males court prior to mating. Such variation in reproductive traits is of interest to evolutionary biologists because it has the potential to limit gene flow among populations, contributing to speciation. Here, we investigate whether large male body size and modified forefemur are associated with higher male mating success within populations, whether these traits are associated with higher mating success among populations, and if these traits carry viability costs that could constrain their response to sexual selection. Flies from five distinct populations were reared at high or low food, generating high and low quality males. The expression of body size, forelimb morphology and courtship rate were each greater at high food, but high food males experienced higher mating success or reduced latency to first copulation in only one of the populations. Among populations, overall mating success increased with the degree of male-bias in overall body size and forelimb modification, suggesting that these traits have evolved as a means of increasing male mating rate. The increased mating success observed in large-male populations raises the question of why variation in magnitude of dimorphism persists among populations. One reason may be that costs of producing a large size constrain the evolution of ever-larger males. We found no evidence that juvenile mortality under food stress was greater for large-male populations, but development time was considerably longer and may represent an important constraint in an ephemeral and competitive growth environment.

Geographic Variation of Diapause and Sensitive Stages of Photoperiodic Response in Laodelphax striatellus Fallén (Hemiptera: Delphacidae)

PubMed Central

Hou, Yang-Yang; Xu, Lan-Zhen; Wu, Yan; Wang, Peng; Shi, Jin-Jian; Zhai, Bao-Ping

2016-01-01

Large numbers of the small brown planthopper Laodelphax striatellus (Fallén) (Hemiptera: Delphacidae) occur in temperate regions, causing severe losses in rice, wheat, and other economically important crops. The planthoppers enter diapause in the third- or fourth-instar nymph stage, induced by short photoperiods and low temperatures. To investigate the geographic variation in L. striatellus diapause, we compared the incidence of nymphal diapause under various constant temperature (20 and 27°C) and a photoperiod of 4:20, 8:16, 10:14, 12:12, 14:10, and 16:8 (L:D) h regimes among three populations collected from Hanoi (21.02° N, 105.85° E, northern Vietnam), Jiangyan (32.51° N, 120.15° E, eastern China), and Changchun (43.89° N, 125.32° E, north-eastern China). Our results indicated that there were significant geographic variations in the diapause of L. striatellus. When the original latitude of the populations increased, higher diapause incidence and longer critical photoperiod (CP) were exhibited. The CPs of the Jiangyan and Changchun populations were ∼12 hr 30 min and 13 hr at 20°C, and 11 hr and 11 hr 20 min at 27°C, respectively. The second- and third-instar nymphs were at the stage most sensitive to the photoperiod. However, when the fourth- and fifth-instar nymphs were transferred to a long photoperiod, the diapause-inducing effect of the short photoperiod on young instars was almost reversed. The considerable geographic variations in the nymphal diapause of L. striatellus reflect their adaptation in response to a variable environment and provide insights to develop effective pest management strategies. PMID:26839318

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

Geographic Variation of Diapause and Sensitive Stages of Photoperiodic Response in Laodelphax striatellus Fallén (Hemiptera: Delphacidae).

PubMed

Hou, Yang-Yang; Xu, Lan-Zhen; Wu, Yan; Wang, Peng; Shi, Jin-Jian; Zhai, Bao-Ping

2016-01-01

Large numbers of the small brown planthopper Laodelphax striatellus (Fallén) (Hemiptera: Delphacidae) occur in temperate regions, causing severe losses in rice, wheat, and other economically important crops. The planthoppers enter diapause in the third- or fourth-instar nymph stage, induced by short photoperiods and low temperatures. To investigate the geographic variation in L. striatellus diapause, we compared the incidence of nymphal diapause under various constant temperature (20 and 27 °C) and a photoperiod of 4:20, 8:16, 10:14, 12:12, 14:10, and 16:8 (L:D) h regimes among three populations collected from Hanoi (21.02° N, 105.85° E, northern Vietnam), Jiangyan (32.51° N, 120.15° E, eastern China), and Changchun (43.89° N, 125.32° E, north-eastern China). Our results indicated that there were significant geographic variations in the diapause of L. striatellus. When the original latitude of the populations increased, higher diapause incidence and longer critical photoperiod (CP) were exhibited. The CPs of the Jiangyan and Changchun populations were ∼ 12 hr 30 min and 13 hr at 20 °C, and 11 hr and 11 hr 20 min at 27 °C, respectively. The second- and third-instar nymphs were at the stage most sensitive to the photoperiod. However, when the fourth- and fifth-instar nymphs were transferred to a long photoperiod, the diapause-inducing effect of the short photoperiod on young instars was almost reversed. The considerable geographic variations in the nymphal diapause of L. striatellus reflect their adaptation in response to a variable environment and provide insights to develop effective pest management strategies. © The Author 2016. Published by Oxford University Press on behalf of the Entomological Society of America.

Phenotypic variation in California populations of valley oak (Quercus lobata Née) sampled along elevational gradients

Treesearch

Ana L. Albarrán-Lara; Jessica W. Wright; Paul F. Gugger; Annette Delfino-Mix; Juan Manuel Peñaloza-Ramírez; Victoria L. Sork

2015-01-01

California oaks exhibit tremendous phenotypic variation throughout their range. This variation reflects phenotypic plasticity in tree response to local environmental conditions as well as genetic differences underlying those phenotypes. In this study, we analyze phenotypic variation in leaf traits for valley oak adults sampled along three elevational transects and in...

Selection and sex-biased dispersal in a coastal shark: the influence of philopatry on adaptive variation.

PubMed

Portnoy, D S; Puritz, J B; Hollenbeck, C M; Gelsleichter, J; Chapman, D; Gold, J R

2015-12-01

Sex-biased dispersal is expected to homogenize nuclear genetic variation relative to variation in genetic material inherited through the philopatric sex. When site fidelity occurs across a heterogeneous environment, local selective regimes may alter this pattern. We assessed spatial patterns of variation in nuclear-encoded, single nucleotide polymorphisms (SNPs) and sequences of the mitochondrial control region in bonnethead sharks (Sphyrna tiburo), a species thought to exhibit female philopatry, collected from summer habitats used for gestation. Geographic patterns of mtDNA haplotypes and putatively neutral SNPs confirmed female philopatry and male-mediated gene flow along the northeastern coast of the Gulf of Mexico. A total of 30 outlier SNP loci were identified; alleles at over half of these loci exhibited signatures of latitude-associated selection. Our results indicate that in species with sex-biased dispersal, philopatry can facilitate sorting of locally adaptive variation, with the dispersing sex facilitating movement of potentially adaptive variation among locations and environments. © 2015 John Wiley & Sons Ltd.

Variations of Scale Height at F-Region Peak Based on Ionosonde Measurements during Solar Maximum over the Crest of Equatorial Ionization Anomaly Region

PubMed Central

Chuo, Yu-Jung

2014-01-01

Scale height is an important parameter in characterizing the shape of the ionosphere and its physical processes. In this study, we attempt to examine and discuss the variation of scale height, H m, around the F-layer peak height during high solar activity at the northern crest of the equatorial ionization anomaly (EIA) region. H m exhibits day-to-day variation and seasonal variation, with a greater average daily variation during daytime in summer. Furthermore, the diurnal variation of H m exhibits an abnormal peak at presunrise during all the seasons, particularly in winter. This increase is also observed in the F2-layer peak height for the same duration with an upward movement associated with thermospheric wind toward the equator; this upward movement increases the N2/O ratio and H m, but it causes a decrease in the F2-layer maximum critical frequency during the presunrise period. PMID:25162048

Morphology, body proportions, and postcranial hypertrophy of a female Neandertal from the Sima de las Palomas, southeastern Spain.

PubMed

Walker, Michael J; Ortega, Jon; Parmová, Klara; López, Mariano V; Trinkaus, Erik

2011-06-21

Considerations of Neandertal geographical variation have been hampered by the dearth of remains from Mediterranean Europe and the absence there of sufficiently complete associated postcrania. The 2006 and 2007 excavation of an articulated partial skeleton of a small adult female Neandertal at the Sima de las Palomas, Murcia, southeastern Spain (Sima de las Palomas 96) provides substantial and secure information on body proportions among southern European Neandertals, as well as further documenting the nature of Neandertal biology in southern Iberia. The remains exhibit a suite of cranial, mandibular, dental, and postcranial features, of both Neandertals and archaic Homo generally, that distinguish them from contemporary and subsequent early modern humans. Its lower limbs exhibit the robustness of later Pleistocene Homo generally, and its upper limbs conform to the pattern of elevated robustness of the Neandertals. Its body proportions, including relative clavicular length, distal limb segment lengths, and body mass to stature indicators, conform to the "cold-adapted" pattern of more northern Neandertals. Palomas 96 therefore documents the presence of a suite of "Neandertal" characteristics in southern Iberia and, along with its small body size, the more "Arctic" body proportions of other European Neandertals despite the warmer climate of southern Iberia during marine isotope stage 3.

Magnetic field variation caused by rotational speed change in a magnetohydrodynamic dynamo.

PubMed

Miyagoshi, Takehiro; Hamano, Yozo

2013-09-20

We have performed numerical magnetohydrodynamic dynamo simulations in a spherical shell with rotational speed or length-of-day (LOD) variation, which is motivated by correlations between geomagnetic field and climatic variations with ice and non-ice ages. The results show that LOD variation leads to magnetic field variation whose amplitude is considerably larger than that of LOD variation. The heat flux at the outer sphere and the zonal flow also change. The mechanism of the magnetic field variation due to LOD variation is also found. The keys are changes of dynamo activity and Joule heating.

Predictability of state-level flood damage in the conterminous United States: the role of hazard, exposure and vulnerability

DOE PAGES

Zhou, Qianqian; Leng, Guoyong; Feng, Leyang

2017-07-13

Understanding historical changes in flood damage and the underlying mechanisms is critical for predicting future changes for better adaptations. In this study, a detailed assessment of flood damage for 1950–1999 is conducted at the state level in the conterminous United States (CONUS). Geospatial datasets on possible influencing factors are then developed by synthesizing natural hazards, population, wealth, cropland and urban area to explore the relations with flood damage. A considerable increase in flood damage in CONUS is recorded for the study period which is well correlated with hazards. Comparably, runoff indexed hazards simulated by the Variable Infiltration Capacity (VIC) modelmore » can explain a larger portion of flood damage variations than precipitation in 84% of the states. Cropland is identified as an important factor contributing to increased flood damage in central US while urbanland exhibits positive and negative relations with total flood damage and damage per unit wealth in 20 and 16 states, respectively. Altogether, flood damage in 34 out of 48 investigated states can be predicted at the 90% confidence level. In extreme cases, ~76% of flood damage variations can be explained in some states, highlighting the potential of future flood damage prediction based on climate change and socioeconomic scenarios.« less

Understanding the General Packing Rearrangements Required for Successful Template Based Modeling of Protein Structure from a CASP Experiment

PubMed Central

Day, Ryan; Joo, Hyun; Chavan, Archana; Lennox, Kristin P.; Chen, Ann; Dahl, David B.; Vannucci, Marina; Tsai, Jerry W.

2012-01-01

As an alternative to the common template based protein structure prediction methods based on main-chain position, a novel side-chain centric approach has been developed. Together with a Bayesian loop modeling procedure and a combination scoring function, the Stone Soup algorithm was applied to the CASP9 set of template based modeling targets. Although the method did not generate as large of perturbations to the template structures as necessary, the analysis of the results gives unique insights into the differences in packing between the target structures and their templates. Considerable variation in packing is found between target and template structures even when the structures are close, and this variation is found due to 2 and 3 body packing interactions. Outside the inherent restrictions in packing representation of the PDB, the first steps in correctly defining those regions of variable packing have been mapped primarily to local interactions, as the packing at the secondary and tertiary structure are largely conserved. Of the scoring functions used, a loop scoring function based on water structure exhibited some promise for discrimination. These results present a clear structural path for further development of a side-chain centered approach to template based modeling. PMID:23266765

Evolutionary rates for multivariate traits: the role of selection and genetic variation.

PubMed

Pitchers, William; Wolf, Jason B; Tregenza, Tom; Hunt, John; Dworkin, Ian

2014-08-19

A fundamental question in evolutionary biology is the relative importance of selection and genetic architecture in determining evolutionary rates. Adaptive evolution can be described by the multivariate breeders' equation (Δz(-)=Gβ), which predicts evolutionary change for a suite of phenotypic traits (Δz(-)) as a product of directional selection acting on them (β) and the genetic variance-covariance matrix for those traits (G ). Despite being empirically challenging to estimate, there are enough published estimates of G and β to allow for synthesis of general patterns across species. We use published estimates to test the hypotheses that there are systematic differences in the rate of evolution among trait types, and that these differences are, in part, due to genetic architecture. We find some evidence that sexually selected traits exhibit faster rates of evolution compared with life-history or morphological traits. This difference does not appear to be related to stronger selection on sexually selected traits. Using numerous proposed approaches to quantifying the shape, size and structure of G, we examine how these parameters relate to one another, and how they vary among taxonomic and trait groupings. Despite considerable variation, they do not explain the observed differences in evolutionary rates. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Plasmonic Metasurfaces Based on Nanopin-Cavity Resonator for Quantitative Colorimetric Ricin Sensing.

PubMed

Fan, Jiao-Rong; Zhu, Jia; Wu, Wen-Gang; Huang, Yun

2017-01-01

In view of the toxic potential of a bioweapon threat, rapid visual recognition and sensing of ricin has been of considerable interest while remaining a challenging task up to date. In this study, a gold nanopin-based colorimetric sensor is developed realizing a multicolor variation for ricin qualitative recognition and analysis. It is revealed that such plasmonic metasurfaces based on nanopin-cavity resonator exhibit reflective color appearance, due to the excitation of standing-wave resonances of narrow bandwidth in visible region. This clear color variation is a consequence of the reflective color mixing defined by different resonant wavelengths. In addition, the colored metasurfaces appear sharp color difference in a narrow refractive index range, which makes them especially well-suited for sensing applications. Therefore, this antibody-functionalized nanopin-cavity biosensor features high sensitivity and fast response, allowing for visual quantitative ricin detection within the range of 10-120 ng mL -1 (0.15 × 10 -9 -1.8 × 10 -9 m), a limit of detection of 10 ng mL -1 , and the typical measurement time of less than 10 min. The on-chip integration of such nanopin metasurfaces to portable colorimetric microfluidic device may be envisaged for the quantitative studies of a variety of biochemical molecules. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Phenotypic diversity, population structure and stress protein-based capacitoring in populations of Xeropicta derbentina, a heat-tolerant land snail species.

PubMed

Di Lellis, Maddalena A; Sereda, Sergej; Geißler, Anna; Picot, Adrien; Arnold, Petra; Lang, Stefanie; Troschinski, Sandra; Dieterich, Andreas; Hauffe, Torsten; Capowiez, Yvan; Mazzia, Christophe; Knigge, Thomas; Monsinjon, Tiphaine; Krais, Stefanie; Wilke, Thomas; Triebskorn, Rita; Köhler, Heinz-R

2014-11-01

The shell colour of many pulmonate land snail species is highly diverse. Besides a genetic basis, environmentally triggered epigenetic mechanisms including stress proteins as evolutionary capacitors are thought to influence such phenotypic diversity. In this study, we investigated the relationship of stress protein (Hsp70) levels with temperature stress tolerance, population structure and phenotypic diversity within and among different populations of a xerophilic Mediterranean snail species (Xeropicta derbentina). Hsp70 levels varied considerably among populations, and were significantly associated with shell colour diversity: individuals in populations exhibiting low diversity expressed higher Hsp70 levels both constitutively and under heat stress than those of phenotypically diverse populations. In contrast, population structure (cytochrome c oxidase subunit I gene) did not correlate with phenotypic diversity. However, genetic parameters (both within and among population differences) were able to explain variation in Hsp70 induction at elevated but non-pathologic temperatures. Our observation that (1) population structure had a high explanatory potential for Hsp70 induction and that (2) Hsp70 levels, in turn, correlated with phenotypic diversity while (3) population structure and phenotypic diversity failed to correlate provides empirical evidence for Hsp70 to act as a mediator between genotypic variation and phenotype and thus for chaperone-driven evolutionary capacitance in natural populations.

Predictability of state-level flood damage in the conterminous United States: the role of hazard, exposure and vulnerability

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

Zhou, Qianqian; Leng, Guoyong; Feng, Leyang

Understanding historical changes in flood damage and the underlying mechanisms is critical for predicting future changes for better adaptations. In this study, a detailed assessment of flood damage for 1950–1999 is conducted at the state level in the conterminous United States (CONUS). Geospatial datasets on possible influencing factors are then developed by synthesizing natural hazards, population, wealth, cropland and urban area to explore the relations with flood damage. A considerable increase in flood damage in CONUS is recorded for the study period which is well correlated with hazards. Comparably, runoff indexed hazards simulated by the Variable Infiltration Capacity (VIC) modelmore » can explain a larger portion of flood damage variations than precipitation in 84% of the states. Cropland is identified as an important factor contributing to increased flood damage in central US while urbanland exhibits positive and negative relations with total flood damage and damage per unit wealth in 20 and 16 states, respectively. Altogether, flood damage in 34 out of 48 investigated states can be predicted at the 90% confidence level. In extreme cases, ~76% of flood damage variations can be explained in some states, highlighting the potential of future flood damage prediction based on climate change and socioeconomic scenarios.« less

Understanding the general packing rearrangements required for successful template based modeling of protein structure from a CASP experiment.

PubMed

Day, Ryan; Joo, Hyun; Chavan, Archana C; Lennox, Kristin P; Chen, Y Ann; Dahl, David B; Vannucci, Marina; Tsai, Jerry W

2013-02-01

As an alternative to the common template based protein structure prediction methods based on main-chain position, a novel side-chain centric approach has been developed. Together with a Bayesian loop modeling procedure and a combination scoring function, the Stone Soup algorithm was applied to the CASP9 set of template based modeling targets. Although the method did not generate as large of perturbations to the template structures as necessary, the analysis of the results gives unique insights into the differences in packing between the target structures and their templates. Considerable variation in packing is found between target and template structures even when the structures are close, and this variation is found due to 2 and 3 body packing interactions. Outside the inherent restrictions in packing representation of the PDB, the first steps in correctly defining those regions of variable packing have been mapped primarily to local interactions, as the packing at the secondary and tertiary structure are largely conserved. Of the scoring functions used, a loop scoring function based on water structure exhibited some promise for discrimination. These results present a clear structural path for further development of a side-chain centered approach to template based modeling. Copyright © 2012 Elsevier Ltd. All rights reserved.

Shot sequencing based on biological equivalent dose considerations for multiple isocenter Gamma Knife radiosurgery

NASA Astrophysics Data System (ADS)

Ma, Lijun; Lee, Letitia; Barani, Igor; Hwang, Andrew; Fogh, Shannon; Nakamura, Jean; McDermott, Michael; Sneed, Penny; Larson, David A.; Sahgal, Arjun

2011-11-01

Rapid delivery of multiple shots or isocenters is one of the hallmarks of Gamma Knife radiosurgery. In this study, we investigated whether the temporal order of shots delivered with Gamma Knife Perfexion would significantly influence the biological equivalent dose for complex multi-isocenter treatments. Twenty single-target cases were selected for analysis. For each case, 3D dose matrices of individual shots were extracted and single-fraction equivalent uniform dose (sEUD) values were determined for all possible shot delivery sequences, corresponding to different patterns of temporal dose delivery within the target. We found significant variations in the sEUD values among these sequences exceeding 15% for certain cases. However, the sequences for the actual treatment delivery were found to agree (<3%) and to correlate (R2 = 0.98) excellently with the sequences yielding the maximum sEUD values for all studied cases. This result is applicable for both fast and slow growing tumors with α/β values of 2 to 20 according to the linear-quadratic model. In conclusion, despite large potential variations in different shot sequences for multi-isocenter Gamma Knife treatments, current clinical delivery sequences exhibited consistent biological target dosing that approached that maximally achievable for all studied cases.

Quantitative genetic insights into the coevolutionary dynamics of male and female genitalia

PubMed Central

Evans, Jonathan P.; van Lieshout, Emile; Gasparini, Clelia

2013-01-01

The spectacular variability that typically characterizes male genital traits has largely been attributed to the role of sexual selection. Among the evolutionary mechanisms proposed to account for this diversity, two processes in particular have generated considerable interest. On the one hand, females may exploit postcopulatory mechanisms of selection to favour males with preferred genital traits (cryptic female choice; CFC), while on the other hand females may evolve structures or behaviours that mitigate the direct costs imposed by male genitalia (sexual conflict; SC). A critical but rarely explored assumption underlying both processes is that male and female reproductive traits coevolve, either via the classic Fisherian model of preference-trait coevolution (CFC) or through sexually antagonistic selection (SC). Here, we provide evidence for this prediction in the guppy (Poecilia reticulata), a polyandrous livebearing fish in which males transfer sperm internally to females via consensual and forced matings. Our results from a paternal half-sibling breeding design reveal substantial levels of additive genetic variation underlying male genital size and morphology—two traits known to predict mating success during non-consensual matings. Our subsequent finding that physically interacting female genital traits exhibit corresponding levels of genetic (co)variation reveals the potential intersexual coevolutionary dynamics of male and female genitalia, thereby fulfilling a fundamental assumption underlying CFC and SC theory. PMID:23720546

Intra-Specific Latitudinal Clines in Leaf Carbon, Nitrogen, and Phosphorus and their Underlying Abiotic Correlates in Ruellia Nudiflora.

PubMed

Abdala-Roberts, Luis; Covelo, Felisa; Parra-Tabla, Víctor; Terán, Jorge C Berny Mier Y; Mooney, Kailen A; Moreira, Xoaquín

2018-01-12

While plant intra-specific variation in the stoichiometry of nutrients and carbon is well documented, clines for such traits have been less studied, despite their potential to reveal the mechanisms underlying such variation. Here we analyze latitudinal variation in the concentration of leaf nitrogen (N), phosphorus (P), carbon (C) and their ratios across 30 populations of the perennial herb Ruellia nudiflora. In addition, we further determined whether climatic and soil variables underlie any such latitudinal clines in leaf traits. The sampled transect spanned 5° latitude (ca. 900 km) and exhibited a four-fold precipitation gradient and 2 °C variation in mean annual temperature. We found that leaf P concentration increased with precipitation towards lower latitudes, whereas N and C did not exhibit latitudinal clines. In addition, N:P and C:P decreased towards lower latitudes and latitudinal variation in the former was weakly associated with soil conditions (clay content and cation exchange capacity); C:N did not exhibit a latitudinal gradient. Overall, these results emphasize the importance of addressing and disentangling the simultaneous effects of abiotic factors associated with intra-specific clines in plant stoichiometric traits, and highlight the previously underappreciated influence of abiotic factors on plant nutrients operating under sharp abiotic gradients over smaller spatial scales.

Diurnal Variation in Gravity Wave Activity at Low and Middle Latitudes

NASA Technical Reports Server (NTRS)

Andrioli, V. F.; Fritts, D. C.; Batista, P. P.; Clemesha, B. R.; Janches, Diego

2013-01-01

We employ a modified composite day extension of the Hocking (2005) analysis method to study gravity wave (GW) activity in the mesosphere and lower thermosphere using 4 meteor radars spanning latitudes from 7deg S to 53.6deg S. Diurnal and semidiurnal modulations were observed in GW variances over all sites. Semidiurnal modulation with downward phase propagation was observed at lower latitudes mainly near the equinoxes. Diurnal modulations occur mainly near solstice and, except for the zonal component at Cariri (7deg S), do not exhibit downward phase propagation. At a higher latitude (SAAMER, 53.6deg S) these modulations are only observed in the meridional component where we can observe diurnal variation from March to May, and semidiurnal, during January, February, October (above 88 km) and November. Some of these modulations with downward phase progression correlate well with wind shear. When the wind shear is well correlated with the maximum of the variances the diurnal tide has its largest amplitudes, i.e., near equinox. Correlations exhibiting variations with tidal phases suggest significant GW-tidal interactions that have different characters depending on the tidal components and possible mean wind shears. Modulations that do not exhibit phase variations could be indicative of diurnal variations in GW sources.

Within-individual variation in bullfrog vocalizations: implications for a vocally mediated social recognition system.

PubMed

Bee, Mark A

2004-12-01

Acoustic signals provide a basis for social recognition in a wide range of animals. Few studies, however, have attempted to relate the patterns of individual variation in signals to behavioral discrimination thresholds used by receivers to discriminate among individuals. North American bullfrogs (Rana catesbeiana) discriminate among familiar and unfamiliar individuals based on individual variation in advertisement calls. The sources, patterns, and magnitudes of variation in eight acoustic properties of multiple-note advertisement calls were examined to understand how patterns of within-individual variation might either constrain, or provide additional cues for, vocal recognition. Six of eight acoustic properties exhibited significant note-to-note variation within multiple-note calls. Despite this source of within-individual variation, all call properties varied significantly among individuals, and multivariate analyses indicated that call notes were individually distinct. Fine-temporal and spectral call properties exhibited less within-individual variation compared to gross-temporal properties and contributed most toward statistically distinguishing among individuals. Among-individual differences in the patterns of within-individual variation in some properties suggest that within-individual variation could also function as a recognition cue. The distributions of among-individual and within-individual differences were used to generate hypotheses about the expected behavioral discrimination thresholds of receivers.

Modulation of MJO-Associated North Pacific Storm Track Variation by the QBO

NASA Astrophysics Data System (ADS)

Wang, J.; Kim, H. M.; Chang, E. K. M.; Son, S. W.

2017-12-01

The North Pacific storm track (NPST) is a preferred region of extratropical synoptic-scale disturbances which plays a critical role in the mid-latitude weather and climate variability during the cool season (October to March). Extreme precipitation, heat/cold events, and sub-seasonal variation of the North Atlantic Oscillation (NAO) are found to be caused/modulated by the NPST. Thus investigating the variability of the NPST and the possible precursors for its variation is an important field of research. The Madden-Julian Oscillation (MJO) is the dominant intraseasonal mode in the tropics. A teleconnection between the MJO and the NPST has been realized recently. However, the MJO-NPST relationship shows a significant dependence on the background state. As previous studies primarily kept an eye on the modulation of El Niño Southern Oscillation (ENSO) on the MJO-NPST relationship, this study focuses on the role of the Quasi-Biennial Oscillation (QBO) because the QBO is suggested to make a much larger contribution to the interannual variability of the MJO than ENSO does. Results of this study show a regulation of the MJO-NPST relationship by different phases of the QBO. The amplitude of the MJO associated NPST variation is generally larger in the easterly phase of the QBO (EQBO) than in westerly phase of the QBO (WQBO). The pattern of the NPST variation also exhibits significant differences between the two QBO phases. The analysis of the underlying mechanism from the perspective of intraseasonal mean flow indicates an important role of the MJO associated baroclinicity in the enhanced amplitude of the NPST variation in EQBO years. On the other hand, the pattern differences in the NPST variation during different QBO phases result from changes in the intraseasonal baroclinic energy conversion and corresponding energy propagation. The results of this study suggest a consideration of the QBO impact in reproducing the MJO-midlatitudes teleconnection in general circulation models (GCMs). This study also provides a potential route for the improvement of the sub-seasonal prediction of extratropical storm activities.

Radiation effects on moisture variation in ponderosa pine litter

Treesearch

Clive M. Countryman

1977-01-01

This exploratory study indicated that considerable variation in the moisture content of litter can occur within short horizontal distances. The variations ere found to be caused primarily by differences in the amount of solar radiation received by the litter and in the degree of cooling by radiation at night. Because actual fuel moisture lags behind equilibrium...

The Relationship between Charge Nurse Leadership Style and Staff Nurse Job Satisfaction

DTIC Science & Technology

1985-12-01

8217 Leadership Styles and Number of Each Style ............................................ 43 13. Staff Nurse Job Satisfaction Information and Charge -a Nurse... leadership styles , were possible: 1. high consideration-high structure 2. high consideration-moderate structure 3. high consideration-low structure. 4...exhibit particular leadership styles . The study also revealed other factors relating to job satisfaction among staff nurses, which can be used by nurses

Timescales alter the inferred strength and temporal consistency of intraspecific diet specialization

USGS Publications Warehouse

Novak, Mark; Tinker, M. Tim

2015-01-01

Many populations consist of individuals that differ substantially in their diets. Quantification of the magnitude and temporal consistency of such intraspecific diet variation is needed to understand its importance, but the extent to which different approaches for doing so reflect instantaneous vs. time-aggregated measures of individual diets may bias inferences. We used direct observations of sea otter individuals (Enhydra lutris nereis) to assess how: (1) the timescale of sampling, (2) under-sampling, and (3) the incidence- vs. frequency-based consideration of prey species affect the inferred strength and consistency of intraspecific diet variation. Analyses of feeding observations aggregated over hourly to annual intervals revealed a substantial bias associated with time aggregation that decreases the inferred magnitude of specialization and increases the inferred consistency of individuals’ diets. Time aggregation also made estimates of specialization more sensitive to the consideration of prey frequency, which decreased estimates relative to the use of prey incidence; time aggregation did not affect the extent to which under-sampling contributed to its overestimation. Our analyses demonstrate the importance of studying intraspecific diet variation with an explicit consideration of time and thereby suggest guidelines for future empirical efforts. Failure to consider time will likely produce inconsistent predictions regarding the effects of intraspecific variation on predator–prey interactions.

Variation of surface water spectral response as a function of in situ sampling technique

NASA Technical Reports Server (NTRS)

Davis, Bruce A.; Hodgson, Michael E.

1988-01-01

Tests were carried out to determine the spectral variation contributed by a particular sampling technique. A portable radiometer was used to measure the surface water spectral response. Variation due to the reflectance of objects near the radiometer (i.e., the boat side) during data acquisition was studied. Consideration was also given to the variation due to the temporal nature of the phenomena (i.e., wave activity).

Environmental variation is directly responsible for short- but not long-term variation in forest-atmosphere carbon exchange

Treesearch

Andrew D. Richardson; David Y. Hollinger; John D. Aber; Scott V. Ollinger; Bobby H. Braswell

2007-01-01

Tower-based eddy covariance measurements of forest-atmosphere carbon dioxide (CO2) exchange from many sites around the world indicate that there is considerable year-to-year variation in net ecosystem exchange (NEE). Here, we use a statistical modeling approach to partition the interannual variability in NEE (and its component fluxes, ecosystem...

Genetic variation in tree structure and its relation to size in Douglas-fir: II. crown form, branch characters, and foliage characters.

Treesearch

J.B. St. Clair

1994-01-01

Genetic variation and covariation among traits of tree size and structure were assessed in an 18-year-old Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) genetic test in the Coast Range of Oregon. Considerable genetic variation was found for relative crown width; stem increment per crown projection area; leaf...

Mutational analysis of Kex2 recognition sites and a disulfide bond in tannase from Aspergillus oryzae.

PubMed

Koseki, Takuya; Otsuka, Motohiro; Mizuno, Toshiyuki; Shiono, Yoshihito

2017-01-22

Aspergillus oryzae tannase (AoTanA), which contains two Kex2 recognition sites at positions Arg311 and Arg316, consists of two subunits that are generated by the cleavage of tannase gene product by the Kex2 protease. Based on the crystal structure of feruloyl esterase from Aspergillus oryzae (AoFaeB), which has been classified as a member of the fungal tannase family, the catalytic triad residues of AoTanA are predicted to be Ser195, Asp455, and His501, with the serine and histidine residues brought together by a disulfide bond of the neighboring cysteines, Cys194 and Cys502. In this study, we investigated the functional role of the Kex2 recognition sites and disulfide bond between the neighboring cysteines in AoTanA. We constructed a double variant (R311A/R316A), a seven amino-acid deletion variant of region Lys310-Arg316 (ΔKR), and two single variants (C194A and C502A). While the R311A/R316A variant exhibited the two bands similar to wild type by SDS-PAGE after treatment with endoglycosidase H, the ΔKR variant exhibited only one band. R311A/R316A variation had no effect on tannase activity and stability. Meanwhile, the ΔKR variant exhibited higher activity compared to the wild-type. The activities of the C194A and C502A variants decreased considerably (<0.24% of the wild-type) toward methyl gallate. Copyright © 2016 Elsevier Inc. All rights reserved.

Sex-dependent effects of developmental exposure to bisphenol A and ethinyl estradiol on metabolic parameters and voluntary physical activity

PubMed Central

Johnson, S. A.; Painter, M. S.; Javurek, A. B.; Ellersieck, M. R.; Wiedmeyer, C. E.; Thyfault, J. P.; Rosenfeld, C. S.

2016-01-01

Endocrine disrupting chemicals (EDC) have received considerable attention as potential obesogens. Past studies examining obesogenic potential of one widespread EDC, bisphenol A (BPA), have generally focused on metabolic and adipose tissue effects. However, physical inactivity has been proposed to be a leading cause of obesity. A paucity of studies has considered whether EDC, including BPA, affects this behavior. To test whether early exposure to BPA and ethinyl estradiol (EE, estrogen present in birth control pills) results in metabolic and such behavioral disruptions, California mice developmentally exposed to BPA and EE were tested as adults for energy expenditure (indirect calorimetry), body composition (echoMRI) and physical activity (measured by beam breaks and voluntary wheel running). Serum glucose and metabolic hormones were measured. No differences in body weight or food consumption were detected. BPA-exposed females exhibited greater variation in weight than females in control and EE groups. During the dark and light cycles, BPA females exhibited a higher average respiratory quotient than control females, indicative of metabolizing carbohydrates rather than fats. Various assessments of voluntary physical activity in the home cage confirmed that during the dark cycle, BPA and EE-exposed females were significantly less active in this setting than control females. Similar effects were not observed in BPA or EE-exposed males. No significant differences were detected in serum glucose, insulin, adiponectin and leptin concentrations. Results suggest that females developmentally exposed to BPA exhibit decreased motivation to engage in voluntary physical activity and altered metabolism of carbohydrates v. fats, which could have important health implications. PMID:26378919

Mini-review: Strategies for Variation and Evolution of Bacterial Antigens

PubMed Central

Foley, Janet

2015-01-01

Across the eubacteria, antigenic variation has emerged as a strategy to evade host immunity. However, phenotypic variation in some of these antigens also allows the bacteria to exploit variable host niches as well. The specific mechanisms are not shared-derived characters although there is considerable convergent evolution and numerous commonalities reflecting considerations of natural selection and biochemical restraints. Unlike in viruses, mechanisms of antigenic variation in most bacteria involve larger DNA movement such as gene conversion or DNA rearrangement, although some antigens vary due to point mutations or modified transcriptional regulation. The convergent evolution that promotes antigenic variation integrates various evolutionary forces: these include mutations underlying variant production; drift which could remove alleles especially early in infection or during life history phases in arthropod vectors (when the bacterial population size goes through a bottleneck); selection not only for any particular variant but also for the mechanism for the production of variants (i.e., selection for mutability); and overcoming negative selection against variant production. This review highlights the complexities of drivers of antigenic variation, in particular extending evaluation beyond the commonly cited theory of immune evasion. A deeper understanding of the diversity of purpose and mechanisms of antigenic variation in bacteria will contribute to greater insight into bacterial pathogenesis, ecology and coevolution with hosts. PMID:26288700

Quantifying Proportional Variability

PubMed Central

Heath, Joel P.; Borowski, Peter

2013-01-01

Real quantities can undergo such a wide variety of dynamics that the mean is often a meaningless reference point for measuring variability. Despite their widespread application, techniques like the Coefficient of Variation are not truly proportional and exhibit pathological properties. The non-parametric measure Proportional Variability (PV) [1] resolves these issues and provides a robust way to summarize and compare variation in quantities exhibiting diverse dynamical behaviour. Instead of being based on deviation from an average value, variation is simply quantified by comparing the numbers to each other, requiring no assumptions about central tendency or underlying statistical distributions. While PV has been introduced before and has already been applied in various contexts to population dynamics, here we present a deeper analysis of this new measure, derive analytical expressions for the PV of several general distributions and present new comparisons with the Coefficient of Variation, demonstrating cases in which PV is the more favorable measure. We show that PV provides an easily interpretable approach for measuring and comparing variation that can be generally applied throughout the sciences, from contexts ranging from stock market stability to climate variation. PMID:24386334

Sex, race, and consideration of bariatric surgery among primary care patients with moderate to severe obesity.

PubMed

Wee, Christina C; Huskey, Karen W; Bolcic-Jankovic, Dragana; Colten, Mary Ellen; Davis, Roger B; Hamel, Marybeth

2014-01-01

Bariatric surgery is one of few obesity treatments to produce substantial weight loss but only a small proportion of medically-eligible patients, especially men and racial minorities, undergo bariatric surgery. To describe primary care patients' consideration of bariatric surgery, potential variation by sex and race, and factors that underlie any variation. Telephone interview of 337 patients with a body mass index or BMI > 35 kg/m(2) seen at four diverse primary care practices in Greater-Boston. Patients' consideration of bariatric surgery. Of 325 patients who had heard of bariatric surgery, 34 % had seriously considered surgery. Men were less likely than women and African Americans were less likely than Caucasian patients to have considered surgery after adjustment for sociodemographics and BMI. Comorbid conditions did not explain sex and racial differences but racial differences dissipated after adjustment for quality of life (QOL), which tended to be higher among African American than Caucasian patients. Physician recommendation of bariatric surgery was independently associated with serious consideration for surgery [OR 4.95 (95 % CI 2.81-8.70)], but did not explain variation in consideration of surgery across sex and race. However, if recommended by their doctor, men were as willing and African American and Hispanic patients were more willing to consider bariatric surgery than their respective counterparts after adjustment. Nevertheless, only 20 % of patients reported being recommended bariatric surgery by their doctor and African Americans and men were less likely to receive this recommendation; racial differences in being recommended surgery were also largely explained by differences in QOL. High perceived risk to bariatric surgery was the most commonly cited barrier; financial concerns were uncommonly cited. Single geographic region; examined consideration and not who eventually proceeded with bariatric surgery. African Americans and men were less likely to have considered bariatric surgery and were less likely to have been recommended surgery by their doctors. Differences in how obesity affects QOL appear to account for some of these variations. High perceived risk rather than financial barrier was the major deterrent for patients.

Immunogenetics as a tool in anthropological studies

PubMed Central

Sanchez-Mazas, Alicia; Fernandez-Viña, Marcelo; Middleton, Derek; Hollenbach, Jill A; Buhler, Stéphane; Di, Da; Rajalingam, Raja; Dugoujon, Jean-Michel; Mack, Steven J; Thorsby, Erik

2011-01-01

The genes coding for the main molecules involved in the human immune system – immunoglobulins, human leucocyte antigen (HLA) molecules and killer-cell immunoglobulin-like receptors (KIR) – exhibit a very high level of polymorphism that reveals remarkable frequency variation in human populations. ‘Genetic marker’ (GM) allotypes located in the constant domains of IgG antibodies have been studied for over 40 years through serological typing, leading to the identification of a variety of GM haplotypes whose frequencies vary sharply from one geographic region to another. An impressive diversity of HLA alleles, which results in amino acid substitutions located in the antigen-binding region of HLA molecules, also varies greatly among populations. The KIR differ between individuals according to both gene content and allelic variation, and also display considerable population diversity. Whereas the molecular evolution of these polymorphisms has most likely been subject to natural selection, principally driven by host–pathogen interactions, their patterns of genetic variation worldwide show significant signals of human geographic expansion, demographic history and cultural diversification. As current developments in population genetic analysis and computer simulation improve our ability to discriminate among different – either stochastic or deterministic – forces acting on the genetic evolution of human populations, the study of these systems shows great promise for investigating both the peopling history of modern humans in the time since their common origin and human adaptation to past environmental (e.g. pathogenic) changes. Therefore, in addition to mitochondrial DNA, Y-chromosome, microsatellites, single nucleotide polymorphisms and other markers, immunogenetic polymorphisms represent essential and complementary tools for anthropological studies. PMID:21480890

Feeding habitat quality and behavioral trade-offs in chimpanzees: a case for species distribution models.

PubMed

Foerster, Steffen; Zhong, Ying; Pintea, Lilian; Murray, Carson M; Wilson, Michael L; Mjungu, Deus C; Pusey, Anne E

2016-01-01

The distribution and abundance of food resources are among the most important factors that influence animal behavioral strategies. Yet, spatial variation in feeding habitat quality is often difficult to assess with traditional methods that rely on extrapolation from plot survey data or remote sensing. Here, we show that maximum entropy species distribution modeling can be used to successfully predict small-scale variation in the distribution of 24 important plant food species for chimpanzees at Gombe National Park, Tanzania. We combined model predictions with behavioral observations to quantify feeding habitat quality as the cumulative dietary proportion of the species predicted to occur in a given location. This measure exhibited considerable spatial heterogeneity with elevation and latitude, both within and across main habitat types. We used model results to assess individual variation in habitat selection among adult chimpanzees during a 10-year period, testing predictions about trade-offs between foraging and reproductive effort. We found that nonswollen females selected the highest-quality habitats compared with swollen females or males, in line with predictions based on their energetic needs. Swollen females appeared to compromise feeding in favor of mating opportunities, suggesting that females rather than males change their ranging patterns in search of mates. Males generally occupied feeding habitats of lower quality, which may exacerbate energetic challenges of aggression and territory defense. Finally, we documented an increase in feeding habitat quality with community residence time in both sexes during the dry season, suggesting an influence of familiarity on foraging decisions in a highly heterogeneous landscape.

The eye lens: age-related trends and individual variations in refractive index and shape parameters.

PubMed

Pierscionek, Barbara; Bahrami, Mehdi; Hoshino, Masato; Uesugi, Kentaro; Regini, Justyn; Yagi, Naoto

2015-10-13

The eye lens grows throughout life by cell accrual on its surface and can change shape to adjust the focussing power of the eye. Varying concentrations of proteins in successive cell layers create a refractive index gradient. The continued growth of the lens and age-related changes in proteins render it less able to alter shape with loss of capacity by the end of the sixth decade of life. Growth and protein ageing alter the refractive index but as accurate measurement of this parameter is difficult, the nature of such alterations remains uncertain. The most accurate method to date for measuring refractive index in intact lenses has been developed at the SPring-8 synchrotron. The technique, based on Talbot interferometry, has an X-ray source and was used to measure refractive index in sixty-six human lenses, aged from 16 to 91 years. Height and width were measured for forty-five lenses. Refractive index contours show decentration in some older lenses but individual variations mask age-related trends. Refractive index profiles along the optic axis have relatively flat central sections with distinct micro-fluctuations and a steep gradient in the cortex but do not exhibit an age-related trend. The refractive index profiles in the equatorial aspect show statistical significance with age, particularly for lenses below the age of sixty that had capacity to alter shape in vivo. The maximum refractive index in the lens centre decreases slightly with age with considerable scatter in the data and there are age-related variations in sagittal thickness and equatorial height.

Differential polarization laser scanning microscopy: biological applications

NASA Astrophysics Data System (ADS)

Steinbach, G.; Besson, F.; Pomozi, I.; Garab, G.

2005-09-01

With the aid of a differential polarization (DP) apparatus, developed in our laboratory and attached to our laser scanning confocal microscope, we can measure the magnitude and spatial distribution of 8 different DP quantities: linear and circular dichroism (LD&CD), linear and circular anisotropy of the emission (R and CPL, confocal), fluorescence detected dichroisms (FDLD&FDCD, confocal), linear birefringence (LB), and the degree of polarization of fluorescence emission (P, confocal). The attachment uses high frequency modulation and subsequent demodulation, via lock-in amplifier, of the detected intensity values, and records and displays pixel-by-pixel the measured DP quantity. These microscopic DP data carry important physical information on the molecular architecture of anisotropically organized samples. Microscopic DP measurements are thought to be of particular importance in biology. In most biological samples anisotropy is difficult to determine with conventional, macroscopic DP measurements and microscopic variations are of special significance. In this paper, we describe the method of LB imaging. Using magnetically oriented isolated chloroplasts trapped in polyacrylamide gel, we demonstrate that LB can be determined with high sensitivity and good spatial resolution. Granal thylakoid membranes in edge-aligned orientation exhibited strong LB, with large variations in its sign and magnitude. In face-aligned position LB was considerably weaker, and tended to vanish when averaged for the whole image. The strong local variations are attributed to the inherent heterogeneity of the membranes, i.e. to their internal differentiation into multilamellar, stacked membranes (grana), and single thylakoids (stroma membranes). Further details and applications of our DP-LSM will be published elsewhere.

The eye lens: age-related trends and individual variations in refractive index and shape parameters

PubMed Central

Pierscionek, Barbara; Bahrami, Mehdi; Hoshino, Masato; Uesugi, Kentaro; Regini, Justyn; Yagi, Naoto

2015-01-01

The eye lens grows throughout life by cell accrual on its surface and can change shape to adjust the focussing power of the eye. Varying concentrations of proteins in successive cell layers create a refractive index gradient. The continued growth of the lens and age-related changes in proteins render it less able to alter shape with loss of capacity by the end of the sixth decade of life. Growth and protein ageing alter the refractive index but as accurate measurement of this parameter is difficult, the nature of such alterations remains uncertain. The most accurate method to date for measuring refractive index in intact lenses has been developed at the SPring-8 synchrotron. The technique, based on Talbot interferometry, has an X-ray source and was used to measure refractive index in sixty-six human lenses, aged from 16 to 91 years. Height and width were measured for forty-five lenses. Refractive index contours show decentration in some older lenses but individual variations mask age-related trends. Refractive index profiles along the optic axis have relatively flat central sections with distinct micro-fluctuations and a steep gradient in the cortex but do not exhibit an age-related trend. The refractive index profiles in the equatorial aspect show statistical significance with age, particularly for lenses below the age of sixty that had capacity to alter shape in vivo. The maximum refractive index in the lens centre decreases slightly with age with considerable scatter in the data and there are age-related variations in sagittal thickness and equatorial height. PMID:26416418

Aridity increases below-ground niche breadth in grass communities

USGS Publications Warehouse

Butterfield, Bradley J.; Bradford, John B.; Munson, Seth M.; Gremer, Jennifer R.

2017-01-01

Aridity is an important environmental filter in the assembly of plant communities worldwide. The extent to which root traits mediate responses to aridity, and how they are coordinated with leaf traits, remains unclear. Here, we measured variation in root tissue density (RTD), specific root length (SRL), specific leaf area (SLA), and seed size within and among thirty perennial grass communities distributed along an aridity gradient spanning 190–540 mm of climatic water deficit (potential minus actual evapotranspiration). We tested the hypotheses that traits exhibited coordinated variation (1) among species, as well as (2) among communities varying in aridity, and (3) functional diversity within communities declines with increasing aridity, consistent with the “stress-dominance” hypothesis. Across communities, SLA and RTD exhibited a coordinated response to aridity, shifting toward more conservative (lower SLA, higher RTD) functional strategies with increasing aridity. The response of SRL to aridity was more idiosyncratic and was independent of variation in SLA and RTD. Contrary to the stress-dominance hypothesis, the diversity of SRL values within communities increased with aridity, while none of the other traits exhibited significant diversity responses. These results are consistent with other studies that have found SRL to be independent of an SLA–RTD axis of functional variation and suggest that the dynamic nature of soil moisture in arid environments may facilitate a wider array of resource capture strategies associated with variation in SRL.

Sexual selection and the rodent baculum: an intraspecific study in the house mouse (Mus musculus domesticus).

PubMed

Ramm, Steven A; Khoo, Lin; Stockley, Paula

2010-01-01

The rapid divergence of genitalia is a pervasive trend in animal evolution, thought to be due to the action of sexual selection. To test predictions from the sexual selection hypothesis, we here report data on the allometry, variation, plasticity and condition dependence of baculum morphology in the house mouse (Mus musculus domesticus). We find that that baculum size: (a) exhibits no consistent pattern of allometric scaling (baculum size being in most cases unrelated to body size), (b) exhibits low to moderate levels of phenotypic variation, (c) does not exhibit phenotypic plasticity in response to differences in perceived levels of sexual competition and (d) exhibits limited evidence of condition dependence. These patterns provide only limited evidence in support of the sexual selection hypothesis, and no consistent support for any particular sexual selection mechanism; however, more direct measures of how genital morphology influences male fertilization success are required.

Relaxed selection on the CBF/DREB1 regulatory genes and reduced freezing tolerance in the southern range of Arabidopsis thaliana.

PubMed

Zhen, Ying; Ungerer, Mark C

2008-12-01

Elucidating the molecular basis of adaptive phenotypic variation represents a central aim in evolutionary biology. Traits exhibiting patterns of clinal variation represent excellent models for studies of molecular adaptation, especially when variation in phenotype can be linked to organismal fitness in different environments. Natural accessions of the model plant species Arabidopsis thaliana exhibit clinal variation in freezing tolerance that follows a gradient of temperature variability across the species' native range (Zhen Y, Ungerer MC. 2008. Clinal variation in freezing tolerance among natural accessions of A. thaliana. New Phytol. 177:419-427). Here, we report that this pattern of variation is attributable, at least in part, to relaxed purifying selection on members of a small family of transcriptional activators (the CBF/DREB1s) in the species' southern range. These regulatory genes play a critical role in the ability of A. thaliana plants to undergo cold acclimation and thereby achieve maximum freezing tolerance. Relative to accessions from northern regions, accessions of A. thaliana from the southern part of their geographic range exhibit levels of nonsynonymous nucleotide polymorphism that are approximately 2.8-fold higher across this small gene subfamily. Relaxed selection on the CBF/DREB1s in southern accessions also has resulted in multiple mutations in regulatory regions resulting in abrogated expression of particular subfamily members in particular accessions. These coding-region and regulatory mutations compromise the ability of these genes to act as efficient transcriptional activators during the cold acclimation process, as determined by reductions in rates of induction and maximum levels of expression in the downstream genes they regulate. This study highlights the potential role of regulatory genes in underlying adaptive phenotypic variation in nature.

The match-to-match variation of match-running in elite female soccer.

PubMed

Trewin, Joshua; Meylan, César; Varley, Matthew C; Cronin, John

2018-02-01

The purpose of this study was to examine the match-to-match variation of match-running in elite female soccer players utilising GPS, using full-match and rolling period analyses. Longitudinal study. Elite female soccer players (n=45) from the same national team were observed during 55 international fixtures across 5 years (2012-2016). Data was analysed using a custom built MS Excel spreadsheet as full-matches and using a rolling 5-min analysis period, for all players who played 90-min matches (files=172). Variation was examined using co-efficient of variation and 90% confidence limits, calculated following log transformation. Total distance per minute exhibited the smallest variation when both the full-match and peak 5-min running periods were examined (CV=6.8-7.2%). Sprint-efforts were the most variable during a full-match (CV=53%), whilst high-speed running per minute exhibited the greatest variation in the post-peak 5-min period (CV=143%). Peak running periods were observed as slightly more variable than full-match analyses, with the post-peak period very-highly variable. Variability of accelerations (CV=17%) and Player Load (CV=14%) was lower than that of high-speed actions. Positional differences were also present, with centre backs exhibiting the greatest variation in high-speed movements (CV=41-65%). Practitioners and researchers should account for within player variability when examining match performances. Identification of peak running periods should be used to assist worst case scenarios. Whilst micro-sensor technology should be further examined as to its viable use within match-analyses. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Some design considerations for solar-powered aircraft

NASA Technical Reports Server (NTRS)

Phillips, W. H.

1980-01-01

Performance and operating characteristics are presented for a solar powered aircraft intended to remain aloft for long periods. The critical technologies which limit the performance are identified. By using the techniques presented, the effects of variation in the system parameters are studied. Practical design consideration are discussed.

Assessing Conformity to Standards for Treatment Foster Care.

ERIC Educational Resources Information Center

Farmer, Elizabeth M. Z.; Burns, Barbara J.; Dubs, Melanie S.; Thompson, Shealy

2002-01-01

This study examined conformity to the Program Standards for Treatment Foster Care among 42 statewide programs. Findings suggest fair to good overall conformity, with considerable variation among programs. A discussion of methodological and substantive considerations for future research and evaluation using this approach is included. (Contains…

Income, Relationship Quality, and Parenting: Associations with Child Development in Two-Parent Families

PubMed Central

Berger, Lawrence M.; McLanahan, Sara S.

2015-01-01

Prior research suggests considerable heterogeneity in the advantages of living in a two-parent family. Specifically, children living with married biological parents exhibit more favorable outcomes than children living with cohabiting biological parents and with married and cohabiting stepparents. To explain these differences, researchers have focused almost exclusively on differences in the levels of factors such as income, parental relationship quality, and parenting quality across family types. In this paper, we examined whether differences in the benefits associated with these factors might also account for some of the variation in children’s cognition and social-emotional development. Focusing on children at the time they enter kindergarten, we found only weak evidence of differences in benefits across family types. Rather, we found that children living in stepfather families experienced above average levels of parental relationship quality and parenting quality which, in turn, played a protective role vis-à-vis their cognitive and social-emotional development. PMID:26339104

Peer assessment of aviation performance: inconsistent for good reasons.

PubMed

Roth, Wolff-Michael; Mavin, Timothy J

2015-03-01

Research into expertise is relatively common in cognitive science concerning expertise existing across many domains. However, much less research has examined how experts within the same domain assess the performance of their peer experts. We report the results of a modified think-aloud study conducted with 18 pilots (6 first officers, 6 captains, and 6 flight examiners). Pairs of same-ranked pilots were asked to rate the performance of a captain flying in a critical pre-recorded simulator scenario. Findings reveal (a) considerable variance within performance categories, (b) differences in the process used as evidence in support of a performance rating, (c) different numbers and types of facts (cues) identified, and (d) differences in how specific performance events affect choice of performance category and gravity of performance assessment. Such variance is consistent with low inter-rater reliability. Because raters exhibited good, albeit imprecise, reasons and facts, a fuzzy mathematical model of performance rating was developed. The model provides good agreement with observed variations. Copyright © 2014 Cognitive Science Society, Inc.

Broadband and fabrication-tolerant on-chip scalable mode-division multiplexing based on mode-evolution counter-tapered couplers.

PubMed

Wang, Jing; Xuan, Yi; Qi, Minghao; Huang, Haiyang; Li, You; Li, Ming; Chen, Xin; Sheng, Zhen; Wu, Aimin; Li, Wei; Wang, Xi; Zou, Shichang; Gan, Fuwan

2015-05-01

A broadband and fabrication-tolerant on-chip scalable mode-division multiplexing (MDM) scheme based on mode-evolution counter-tapered couplers is designed and experimentally demonstrated on a silicon-on-insulator (SOI) platform. Due to the broadband advantage offered by mode evolution, the two-mode MDM link exhibits a very large, -1  dB bandwidth of >180  nm, which is considerably larger than most of the previously reported MDM links whether they are based on mode-interference or evolution. In addition, the performance metrics remain stable for large-device width deviations from the designed valued by -60  nm to 40 nm, and for temperature variations from -25°C to 75°C. This MDM scheme can be readily extended to higher-order mode multiplexing and a three-mode MDM link is measured with less than -10  dB crosstalk from 1.46 to 1.64 μm wavelength range.

Effect of chromosome constitution variations on the expression of Turner phenotype.

PubMed

Bispo, A V S; Dos Santos, L O; Burégio-Frota, P; Galdino, M B; Duarte, A R; Leal, G F; Araújo, J; Gomes, B; Soares-Ventura, E M; Muniz, M T C; Santos, N

2013-03-13

Turner syndrome (TS) is a chronic disease related to haploinsufficiency of genes that are normally expressed in both X chromosomes in patients with female phenotype that is associated with a wide range of somatic malformations. We made detailed cytogenetic and clinical analysis of 65 patients with TS from the region of Recife, Brazil, to determine the effects of different chromosome constitutions on expression of the TS phenotype. Overall, patients with X-monosomy exhibited a tendency to have more severe phenotypes with higher morbidity, showing its importance in TS prognosis. Additionally, we found rare genetic and phenotypic abnormalities associated with this syndrome. To the best of our knowledge, this is the first case of 45,X,t(11;12)(q22;q22) described as a TS karyotype. Turner patients usually have normal intelligence; however, moderate to severe levels of mental retardation were found in 5 TS cases, which is considerate a very uncommon feature in this syndrome.

Ultrafast Nanoimaging of the Photoinduced Phase Transition Dynamics in VO2.

PubMed

Dönges, Sven A; Khatib, Omar; O'Callahan, Brian T; Atkin, Joanna M; Park, Jae Hyung; Cobden, David; Raschke, Markus B

2016-05-11

Many phase transitions in correlated matter exhibit spatial inhomogeneities with expected yet unexplored effects on the associated ultrafast dynamics. Here we demonstrate the combination of ultrafast nondegenerate pump-probe spectroscopy with far from equilibrium excitation, and scattering scanning near-field optical microscopy (s-SNOM) for ultrafast nanoimaging. In a femtosecond near-field near-IR (NIR) pump and mid-IR (MIR) probe study, we investigate the photoinduced insulator-to-metal (IMT) transition in nominally homogeneous VO2 microcrystals. With pump fluences as high as 5 mJ/cm(2), we can reach three distinct excitation regimes. We observe a spatial heterogeneity on ∼50-100 nm length scales in the fluence-dependent IMT dynamics ranging from <100 fs to ∼1 ps. These results suggest a high sensitivity of the IMT with respect to small local variations in strain, doping, or defects that are difficult to discern microscopically. We provide a perspective with the distinct requirements and considerations of ultrafast spatiotemporal nanoimaging of phase transitions in quantum materials.

Analysis of shared heritability in common disorders of the brain.

PubMed

Anttila, Verneri; Bulik-Sullivan, Brendan; Finucane, Hilary K; Walters, Raymond K; Bras, Jose; Duncan, Laramie; Escott-Price, Valentina; Falcone, Guido J; Gormley, Padhraig; Malik, Rainer; Patsopoulos, Nikolaos A; Ripke, Stephan; Wei, Zhi; Yu, Dongmei; Lee, Phil H; Turley, Patrick; Grenier-Boley, Benjamin; Chouraki, Vincent; Kamatani, Yoichiro; Berr, Claudine; Letenneur, Luc; Hannequin, Didier; Amouyel, Philippe; Boland, Anne; Deleuze, Jean-François; Duron, Emmanuelle; Vardarajan, Badri N; Reitz, Christiane; Goate, Alison M; Huentelman, Matthew J; Kamboh, M Ilyas; Larson, Eric B; Rogaeva, Ekaterina; St George-Hyslop, Peter; Hakonarson, Hakon; Kukull, Walter A; Farrer, Lindsay A; Barnes, Lisa L; Beach, Thomas G; Demirci, F Yesim; Head, Elizabeth; Hulette, Christine M; Jicha, Gregory A; Kauwe, John S K; Kaye, Jeffrey A; Leverenz, James B; Levey, Allan I; Lieberman, Andrew P; Pankratz, Vernon S; Poon, Wayne W; Quinn, Joseph F; Saykin, Andrew J; Schneider, Lon S; Smith, Amanda G; Sonnen, Joshua A; Stern, Robert A; Van Deerlin, Vivianna M; Van Eldik, Linda J; Harold, Denise; Russo, Giancarlo; Rubinsztein, David C; Bayer, Anthony; Tsolaki, Magda; Proitsi, Petra; Fox, Nick C; Hampel, Harald; Owen, Michael J; Mead, Simon; Passmore, Peter; Morgan, Kevin; Nöthen, Markus M; Rossor, Martin; Lupton, Michelle K; Hoffmann, Per; Kornhuber, Johannes; Lawlor, Brian; McQuillin, Andrew; Al-Chalabi, Ammar; Bis, Joshua C; Ruiz, Agustin; Boada, Mercè; Seshadri, Sudha; Beiser, Alexa; Rice, Kenneth; van der Lee, Sven J; De Jager, Philip L; Geschwind, Daniel H; Riemenschneider, Matthias; Riedel-Heller, Steffi; Rotter, Jerome I; Ransmayr, Gerhard; Hyman, Bradley T; Cruchaga, Carlos; Alegret, Montserrat; Winsvold, Bendik; Palta, Priit; Farh, Kai-How; Cuenca-Leon, Ester; Furlotte, Nicholas; Kurth, Tobias; Ligthart, Lannie; Terwindt, Gisela M; Freilinger, Tobias; Ran, Caroline; Gordon, Scott D; Borck, Guntram; Adams, Hieab H H; Lehtimäki, Terho; Wedenoja, Juho; Buring, Julie E; Schürks, Markus; Hrafnsdottir, Maria; Hottenga, Jouke-Jan; Penninx, Brenda; Artto, Ville; Kaunisto, Mari; Vepsäläinen, Salli; Martin, Nicholas G; Montgomery, Grant W; Kurki, Mitja I; Hämäläinen, Eija; Huang, Hailiang; Huang, Jie; Sandor, Cynthia; Webber, Caleb; Muller-Myhsok, Bertram; Schreiber, Stefan; Salomaa, Veikko; Loehrer, Elizabeth; Göbel, Hartmut; Macaya, Alfons; Pozo-Rosich, Patricia; Hansen, Thomas; Werge, Thomas; Kaprio, Jaakko; Metspalu, Andres; Kubisch, Christian; Ferrari, Michel D; Belin, Andrea C; van den Maagdenberg, Arn M J M; Zwart, John-Anker; Boomsma, Dorret; Eriksson, Nicholas; Olesen, Jes; Chasman, Daniel I; Nyholt, Dale R; Avbersek, Andreja; Baum, Larry; Berkovic, Samuel; Bradfield, Jonathan; Buono, Russell; Catarino, Claudia B; Cossette, Patrick; De Jonghe, Peter; Depondt, Chantal; Dlugos, Dennis; Ferraro, Thomas N; French, Jacqueline; Hjalgrim, Helle; Jamnadas-Khoda, Jennifer; Kälviäinen, Reetta; Kunz, Wolfram S; Lerche, Holger; Leu, Costin; Lindhout, Dick; Lo, Warren; Lowenstein, Daniel; McCormack, Mark; Møller, Rikke S; Molloy, Anne; Ng, Ping-Wing; Oliver, Karen; Privitera, Michael; Radtke, Rodney; Ruppert, Ann-Kathrin; Sander, Thomas; Schachter, Steven; Schankin, Christoph; Scheffer, Ingrid; Schoch, Susanne; Sisodiya, Sanjay M; Smith, Philip; Sperling, Michael; Striano, Pasquale; Surges, Rainer; Thomas, G Neil; Visscher, Frank; Whelan, Christopher D; Zara, Federico; Heinzen, Erin L; Marson, Anthony; Becker, Felicitas; Stroink, Hans; Zimprich, Fritz; Gasser, Thomas; Gibbs, Raphael; Heutink, Peter; Martinez, Maria; Morris, Huw R; Sharma, Manu; Ryten, Mina; Mok, Kin Y; Pulit, Sara; Bevan, Steve; Holliday, Elizabeth; Attia, John; Battey, Thomas; Boncoraglio, Giorgio; Thijs, Vincent; Chen, Wei-Min; Mitchell, Braxton; Rothwell, Peter; Sharma, Pankaj; Sudlow, Cathie; Vicente, Astrid; Markus, Hugh; Kourkoulis, Christina; Pera, Joana; Raffeld, Miriam; Silliman, Scott; Boraska Perica, Vesna; Thornton, Laura M; Huckins, Laura M; William Rayner, N; Lewis, Cathryn M; Gratacos, Monica; Rybakowski, Filip; Keski-Rahkonen, Anna; Raevuori, Anu; Hudson, James I; Reichborn-Kjennerud, Ted; Monteleone, Palmiero; Karwautz, Andreas; Mannik, Katrin; Baker, Jessica H; O'Toole, Julie K; Trace, Sara E; Davis, Oliver S P; Helder, Sietske G; Ehrlich, Stefan; Herpertz-Dahlmann, Beate; Danner, Unna N; van Elburg, Annemarie A; Clementi, Maurizio; Forzan, Monica; Docampo, Elisa; Lissowska, Jolanta; Hauser, Joanna; Tortorella, Alfonso; Maj, Mario; Gonidakis, Fragiskos; Tziouvas, Konstantinos; Papezova, Hana; Yilmaz, Zeynep; Wagner, Gudrun; Cohen-Woods, Sarah; Herms, Stefan; Julià, Antonio; Rabionet, Raquel; Dick, Danielle M; Ripatti, Samuli; Andreassen, Ole A; Espeseth, Thomas; Lundervold, Astri J; Steen, Vidar M; Pinto, Dalila; Scherer, Stephen W; Aschauer, Harald; Schosser, Alexandra; Alfredsson, Lars; Padyukov, Leonid; Halmi, Katherine A; Mitchell, James; Strober, Michael; Bergen, Andrew W; Kaye, Walter; Szatkiewicz, Jin Peng; Cormand, Bru; Ramos-Quiroga, Josep Antoni; Sánchez-Mora, Cristina; Ribasés, Marta; Casas, Miguel; Hervas, Amaia; Arranz, Maria Jesús; Haavik, Jan; Zayats, Tetyana; Johansson, Stefan; Williams, Nigel; Dempfle, Astrid; Rothenberger, Aribert; Kuntsi, Jonna; Oades, Robert D; Banaschewski, Tobias; Franke, Barbara; Buitelaar, Jan K; Arias Vasquez, Alejandro; Doyle, Alysa E; Reif, Andreas; Lesch, Klaus-Peter; Freitag, Christine; Rivero, Olga; Palmason, Haukur; Romanos, Marcel; Langley, Kate; Rietschel, Marcella; Witt, Stephanie H; Dalsgaard, Soeren; Børglum, Anders D; Waldman, Irwin; Wilmot, Beth; Molly, Nikolas; Bau, Claiton H D; Crosbie, Jennifer; Schachar, Russell; Loo, Sandra K; McGough, James J; Grevet, Eugenio H; Medland, Sarah E; Robinson, Elise; Weiss, Lauren A; Bacchelli, Elena; Bailey, Anthony; Bal, Vanessa; Battaglia, Agatino; Betancur, Catalina; Bolton, Patrick; Cantor, Rita; Celestino-Soper, Patrícia; Dawson, Geraldine; De Rubeis, Silvia; Duque, Frederico; Green, Andrew; Klauck, Sabine M; Leboyer, Marion; Levitt, Pat; Maestrini, Elena; Mane, Shrikant; De-Luca, Daniel Moreno-; Parr, Jeremy; Regan, Regina; Reichenberg, Abraham; Sandin, Sven; Vorstman, Jacob; Wassink, Thomas; Wijsman, Ellen; Cook, Edwin; Santangelo, Susan; Delorme, Richard; Rogé, Bernadette; Magalhaes, Tiago; Arking, Dan; Schulze, Thomas G; Thompson, Robert C; Strohmaier, Jana; Matthews, Keith; Melle, Ingrid; Morris, Derek; Blackwood, Douglas; McIntosh, Andrew; Bergen, Sarah E; Schalling, Martin; Jamain, Stéphane; Maaser, Anna; Fischer, Sascha B; Reinbold, Céline S; Fullerton, Janice M; Guzman-Parra, José; Mayoral, Fermin; Schofield, Peter R; Cichon, Sven; Mühleisen, Thomas W; Degenhardt, Franziska; Schumacher, Johannes; Bauer, Michael; Mitchell, Philip B; Gershon, Elliot S; Rice, John; Potash, James B; Zandi, Peter P; Craddock, Nick; Ferrier, I Nicol; Alda, Martin; Rouleau, Guy A; Turecki, Gustavo; Ophoff, Roel; Pato, Carlos; Anjorin, Adebayo; Stahl, Eli; Leber, Markus; Czerski, Piotr M; Cruceanu, Cristiana; Jones, Ian R; Posthuma, Danielle; Andlauer, Till F M; Forstner, Andreas J; Streit, Fabian; Baune, Bernhard T; Air, Tracy; Sinnamon, Grant; Wray, Naomi R; MacIntyre, Donald J; Porteous, David; Homuth, Georg; Rivera, Margarita; Grove, Jakob; Middeldorp, Christel M; Hickie, Ian; Pergadia, Michele; Mehta, Divya; Smit, Johannes H; Jansen, Rick; de Geus, Eco; Dunn, Erin; Li, Qingqin S; Nauck, Matthias; Schoevers, Robert A; Beekman, Aartjan Tf; Knowles, James A; Viktorin, Alexander; Arnold, Paul; Barr, Cathy L; Bedoya-Berrio, Gabriel; Bienvenu, O Joseph; Brentani, Helena; Burton, Christie; Camarena, Beatriz; Cappi, Carolina; Cath, Danielle; Cavallini, Maria; Cusi, Daniele; Darrow, Sabrina; Denys, Damiaan; Derks, Eske M; Dietrich, Andrea; Fernandez, Thomas; Figee, Martijn; Freimer, Nelson; Gerber, Gloria; Grados, Marco; Greenberg, Erica; Hanna, Gregory L; Hartmann, Andreas; Hirschtritt, Matthew E; Hoekstra, Pieter J; Huang, Alden; Huyser, Chaim; Illmann, Cornelia; Jenike, Michael; Kuperman, Samuel; Leventhal, Bennett; Lochner, Christine; Lyon, Gholson J; Macciardi, Fabio; Madruga-Garrido, Marcos; Malaty, Irene A; Maras, Athanasios; McGrath, Lauren; Miguel, Eurípedes C; Mir, Pablo; Nestadt, Gerald; Nicolini, Humberto; Okun, Michael S; Pakstis, Andrew; Paschou, Peristera; Piacentini, John; Pittenger, Christopher; Plessen, Kerstin; Ramensky, Vasily; Ramos, Eliana M; Reus, Victor; Richter, Margaret A; Riddle, Mark A; Robertson, Mary M; Roessner, Veit; Rosário, Maria; Samuels, Jack F; Sandor, Paul; Stein, Dan J; Tsetsos, Fotis; Van Nieuwerburgh, Filip; Weatherall, Sarah; Wendland, Jens R; Wolanczyk, Tomasz; Worbe, Yulia; Zai, Gwyneth; Goes, Fernando S; McLaughlin, Nicole; Nestadt, Paul S; Grabe, Hans-Jorgen; Depienne, Christel; Konkashbaev, Anuar; Lanzagorta, Nuria; Valencia-Duarte, Ana; Bramon, Elvira; Buccola, Nancy; Cahn, Wiepke; Cairns, Murray; Chong, Siow A; Cohen, David; Crespo-Facorro, Benedicto; Crowley, James; Davidson, Michael; DeLisi, Lynn; Dinan, Timothy; Donohoe, Gary; Drapeau, Elodie; Duan, Jubao; Haan, Lieuwe; Hougaard, David; Karachanak-Yankova, Sena; Khrunin, Andrey; Klovins, Janis; Kučinskas, Vaidutis; Lee Chee Keong, Jimmy; Limborska, Svetlana; Loughland, Carmel; Lönnqvist, Jouko; Maher, Brion; Mattheisen, Manuel; McDonald, Colm; Murphy, Kieran C; Nenadic, Igor; van Os, Jim; Pantelis, Christos; Pato, Michele; Petryshen, Tracey; Quested, Digby; Roussos, Panos; Sanders, Alan R; Schall, Ulrich; Schwab, Sibylle G; Sim, Kang; So, Hon-Cheong; Stögmann, Elisabeth; Subramaniam, Mythily; Toncheva, Draga; Waddington, John; Walters, James; Weiser, Mark; Cheng, Wei; Cloninger, Robert; Curtis, David; Gejman, Pablo V; Henskens, Frans; Mattingsdal, Morten; Oh, Sang-Yun; Scott, Rodney; Webb, Bradley; Breen, Gerome; Churchhouse, Claire; Bulik, Cynthia M; Daly, Mark; Dichgans, Martin; Faraone, Stephen V; Guerreiro, Rita; Holmans, Peter; Kendler, Kenneth S; Koeleman, Bobby; Mathews, Carol A; Price, Alkes; Scharf, Jeremiah; Sklar, Pamela; Williams, Julie; Wood, Nicholas W; Cotsapas, Chris; Palotie, Aarno; Smoller, Jordan W; Sullivan, Patrick; Rosand, Jonathan; Corvin, Aiden; Neale, Benjamin M

2018-06-22

Disorders of the brain can exhibit considerable epidemiological comorbidity and often share symptoms, provoking debate about their etiologic overlap. We quantified the genetic sharing of 25 brain disorders from genome-wide association studies of 265,218 patients and 784,643 control participants and assessed their relationship to 17 phenotypes from 1,191,588 individuals. Psychiatric disorders share common variant risk, whereas neurological disorders appear more distinct from one another and from the psychiatric disorders. We also identified significant sharing between disorders and a number of brain phenotypes, including cognitive measures. Further, we conducted simulations to explore how statistical power, diagnostic misclassification, and phenotypic heterogeneity affect genetic correlations. These results highlight the importance of common genetic variation as a risk factor for brain disorders and the value of heritability-based methods in understanding their etiology. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Small Molecule Activation by Intermolecular Zr(IV)-Phosphine Frustrated Lewis Pairs.

PubMed

Metters, Owen J; Forrest, Sebastian J K; Sparkes, Hazel A; Manners, Ian; Wass, Duncan F

2016-02-17

We report intermolecular transition metal frustrated Lewis pairs (FLPs) based on zirconocene aryloxide and phosphine moieties that exhibit a broad range of small molecule activation chemistry that has previously been the preserve of only intramolecular pairs. Reactions with D2, CO2, THF, and PhCCH are reported. By contrast with previous intramolecular examples, these systems allow facile access to a variety of steric and electronic characteristics at the Lewis acidic and Lewis basic components, with the three-step syntheses of 10 new intermolecular transition metal FLPs being reported. Systematic variation to the phosphine Lewis base is used to unravel steric considerations, with the surprising conclusion that phosphines with relatively small Tolman steric parameters not only give highly reactive FLPs but are often seen to have the highest selectivity for the desired product. DOSY NMR spectroscopic studies on these systems reveal for the first time the nature of the Lewis acid/Lewis base interactions in transition metal FLPs of this type.

Experimental investigation of the latent heat of vaporization in aqueous nanofluids

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

Lee, Soochan; Phelan, Patrick E., E-mail: phelan@asu.edu; Dai, Lenore

2014-04-14

This paper reports an experimental investigation of the latent heat of vaporization (h{sub fg}) in nanofluids. Two different types of nanoparticles, graphite and silver, suspended in deionized water were exposed to a continuous laser beam (130 mW, 532 nm) to generate boiling. The latent heat of vaporization in the nanofluids was determined by the measured vapor mass generation and the heat input. To ensure that the measured h{sub fg} values are independent of heating method, the experiments were repeated with an electrically heated hot wire as a primary heat input. These experiments show considerable variation in the h{sub fg} of nanofluids.more » That is, graphite nanofluid exhibits an increased h{sub fg} and silver nanofluid shows a decrease in h{sub fg} compared to the value for pure water. As such, these results indicate that relatively low mass fractions of nanoparticles can apparently create large changes in h{sub fg}.« less

Fourwing saltbush (Atriplex canescens) seed transfer zones

Treesearch

Stewart C. Sanderson; Durant E. McArthur

2004-01-01

Atriplex canescens (Pursh.) Nutt. is the most widespread species of perennial Atriplex in North America. Throughout its distributional range, A. canescens shows considerable between-population variation. Some of this variation may be due to phenotypic plasticity but most of it appears to be genetic. Mutations,...

Validation of the Thematic Mapper radiometric and geometric correction algorithms

NASA Technical Reports Server (NTRS)

Fischel, D.

1984-01-01

The radiometric and geometric correction algorithms for Thematic Mapper are critical to subsequent successful information extraction. Earlier Landsat scanners, known as Multispectral Scanners, produce imagery which exhibits striping due to mismatching of detector gains and biases. Thematic Mapper exhibits the same phenomenon at three levels: detector-to-detector, scan-to-scan, and multiscan striping. The cause of these variations has been traced to variations in the dark current of the detectors. An alternative formulation has been tested and shown to be very satisfactory. Unfortunately, the Thematic Mapper detectors exhibit saturation effects suffered while viewing extensive cloud areas, and is not easily correctable. The geometric correction algorithm has been shown to be remarkably reliable. Only minor and modest improvements are indicated and shown to be effective.

Genetic variation in tree structure and its relation to size in Douglas-fir: I. Biomass partitioning, foliage efficiency, stem form, and wood density.

Treesearch

J.B. St. Clair

1994-01-01

Genetic variation and covariation among traits of tree size and structure were assessed in an 18-year-old Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) genetic test in the Coast Range of Oregon. Considerable genetic variation was found in size, biomass partitioning, and wood density, and genetic gains may be...

Development and Comparison of hERG Blocker Classifiers: Assessment on Different Datasets Yields Markedly Different Results.

PubMed

Marchese Robinson, Richard L; Glen, Robert C; Mitchell, John B O

2011-05-16

In recent years, considerable effort has been invested in the development of classification models for prospective hERG inhibitors, due to the implications of hERG blockade for cardiotoxicity and the low throughput of functional hERG assays. We present novel approaches for binary classification which seek to separate strong inhibitors (IC50 <1 µM) from 'non-blockers' exhibiting moderate (1-10 µM) or weak (IC50 ≥10 µM) inhibition, as required by the pharmaceutical industry. Our approaches are based on (discretized) 2D descriptors, selected using Winnow, with additional models generated using Random Forest (RF) and Support Vector Machines (SVMs). We compare our models to those previously developed by Thai and Ecker and by Dubus et al. The purpose of this paper is twofold: 1. To propose that our approaches (with Matthews Correlation Coefficients from 0.40 to 0.87 on truly external test sets, when extrapolation beyond the applicability domain was not evident and sufficient quantities of data were available for training) are competitive with those currently proposed in the literature. 2. To highlight key issues associated with building and assessing truly predictive models, in particular the considerable variation in model performance when training and testing on different datasets. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

'Ogura'-based 'CMS' lines with different nuclear backgrounds of cabbage revealed substantial diversity at morphological and molecular levels.

PubMed

Parkash, Chander; Kumar, Sandeep; Singh, Rajender; Kumar, Ajay; Kumar, Satish; Dey, Shyam Sundar; Bhatia, Reeta; Kumar, Raj

2018-01-01

A comprehensive study on characterization and genetic diversity analysis was carried out in 16 'Ogura'-based 'CMS' lines of cabbage using 14 agro-morphological traits and 29 SSR markers. Agro-morphological characterization depicted considerable variations for different horticultural traits studied. The genotype, ZHA-2, performed better for most of the economically important quantitative traits. Further, gross head weight (0.76), head length (0.60) and head width (0.83) revealed significant positive correlation with net head weight. Dendrogram based on 10 quantitative traits exhibited considerable diversity among different CMS lines and principle component analysis (PCA) indicated that net and gross head weight, and head length and width are the main components of divergence between 16 CMS lines of cabbage. In molecular study, a total of 58 alleles were amplified by 29 SSR primers, averaging to 2.0 alleles in each locus. High mean values of Shannon's Information index (0.62), expected (0.45) and observed (0.32) heterozygosity and polymorphic information content (0.35) depicted substantial polymorphism. Dendrogram based on Jaccard's similarity coefficient constructed two major groups and eight sub-groups, which revealed substantial diversity among different CMS lines. In overall, based on agro-morphological and molecular studies genotype RRMA, ZHA-2 and RCA were found most divergent. Hence, they have immense potential in future breeding programs for the high-yielding hybrid development in cabbage.

Variations in Soft Soil of Troy False Color

NASA Image and Video Library

2009-06-25

The soft soil exposed when wheels of NASA Mars Exploration Rover Spirit dug into a patch of ground dubbed Troy exhibit variations in hue visible in this image, in which the colors have been stretched to emphasize the differences.

Apprenticeship Programme Requirements and Apprenticeship Completion Rates in Canada

ERIC Educational Resources Information Center

Coe, Patrick J.

2013-01-01

The past two decades have seen considerable growth in new apprenticeship registrations in Canada. However, this has not been matched by a corresponding increase in completions. Across provinces, trades and time, there is considerable variation in apprenticeship completion rates. In Canada, apprenticeship programmes are provincially regulated and…

Feed efficiency and the microbiota of the alimentary tract

USDA-ARS?s Scientific Manuscript database

There is considerable variation in the efficiency that cattle convert feed for maintenance and product (body weight gain, milk, and conceptus). Both intake and gain are polygenic traits and to better understand factors that contribute to variation in feed efficiency more defined phenotypes are need...

Evaluation of functional variation in candidate genes for pork quality

USDA-ARS?s Scientific Manuscript database

Considerable variation exists in pork quality traits and consumer perception of pork eating satisfaction is largely driven by tenderness and sensory juiciness scores, which are related to shear force, cooking loss and ultimate pH. Water loss from meat during postmortem storage reduces profitability ...

A Visual Haptic System for Children with Learning Disabilities: Software and Hardware Design Considerations

ERIC Educational Resources Information Center

Subrahmaniyan, Neeraja; Krishnaswamy, Swetha; Chowriappa, Ashirwad; Srimathveeravalli, Govindarajan; Bisantz, Ann; Shriber, Linda; Kesavadas, Thenkurussi

2012-01-01

Research has shown that children with learning disabilities exhibit considerable challenges with visual motor integration. While there are specialized Occupational Therapy interventions aimed at visual motor integration, computer games and virtual toys have now become increasingly popular, forming an integral part of children's learning and play.…

High frequency measurements of reach scale nitrogen uptake in a fourth order river with contrasting hydromorphology and variable water chemistry (Weiße Elster, Germany)

NASA Astrophysics Data System (ADS)

Kunz, Julia Vanessa; Hensley, Robert; Brase, Lisa; Borchardt, Dietrich; Rode, Michael

2017-01-01

River networks exhibit a globally important capacity to retain and process nitrogen. However direct measurement of in-stream removal in higher order streams and rivers has been extremely limited. The recent advent of automated sensors has allowed high frequency measurements, and the development of new passive methods of quantifying nitrogen uptake which are scalable across river size. Here we extend these methods to higher order streams with anthropogenically elevated nitrogen levels, substantial tributaries, complex input signals, and multiple N species. We use a combination of two station time-series and longitudinal profiling of nitrate to assess differences in nitrogen processing dynamics in a natural versus a channelized impounded reach with WWTP effluent impacted water chemistry. Our results suggest that net mass removal rates of nitrate were markedly higher in the unmodified reach. Additionally, seasonal variations in temperature and insolation affected the relative contribution of assimilatory versus dissimilatory uptake processes, with the latter exhibiting a stronger positive dependence on temperature. From a methodological perspective, we demonstrate that a mass balance approach based on high frequency data can be useful in deriving quantitative uptake estimates, even under dynamic inputs and lateral tributary inflow. However, uncertainty in diffuse groundwater inputs and more importantly the effects of alternative nitrogen species, in this case ammonium, pose considerable challenges to this method.

Carbon partitioning in Arabidopsis thaliana is a dynamic process controlled by the plants metabolic status and its circadian clock.

PubMed

Kölling, Katharina; Thalmann, Matthias; Müller, Antonia; Jenny, Camilla; Zeeman, Samuel C

2015-10-01

Plant growth involves the coordinated distribution of carbon resources both towards structural components and towards storage compounds that assure a steady carbon supply over the complete diurnal cycle. We used (14) CO2 labelling to track assimilated carbon in both source and sink tissues. Source tissues exhibit large variations in carbon allocation throughout the light period. The most prominent change was detected in partitioning towards starch, being low in the morning and more than double later in the day. Export into sink tissues showed reciprocal changes. Fewer and smaller changes in carbon allocation occurred in sink tissues where, in most respects, carbon was partitioned similarly, whether the sink leaf assimilated it through photosynthesis or imported it from source leaves. Mutants deficient in the production or remobilization of leaf starch exhibited major alterations in carbon allocation. Low-starch mutants that suffer from carbon starvation at night allocated much more carbon into neutral sugars and had higher rates of export than the wild type, partly because of the reduced allocation into starch, but also because of reduced allocation into structural components. Moreover, mutants deficient in the plant's circadian system showed considerable changes in their carbon partitioning pattern suggesting control by the circadian clock. © 2015 The Authors. Plant, Cell & Environment published by John Wiley & Sons Ltd.

Adaptive introgression as a resource for management and genetic conservation in a changing climate.

PubMed

Hamilton, Jill A; Miller, Joshua M

2016-02-01

Current rates of climate change require organisms to respond through migration, phenotypic plasticity, or genetic changes via adaptation. We focused on questions regarding species' and populations' ability to respond to climate change through adaptation. Specifically, the role adaptive introgression, movement of genetic material from the genome of 1 species into the genome of another through repeated interbreeding, may play in increasing species' ability to respond to a changing climate. Such interspecific gene flow may mediate extinction risk or consequences of limited adaptive potential that result from standing genetic variation and mutation alone, enabling a quicker demographic recovery in response to changing environments. Despite the near dismissal of the potential benefits of hybridization by conservation practitioners, we examined a number of case studies across different taxa that suggest gene flow between sympatric or parapatric sister species or within species that exhibit strong ecotypic differentiation may represent an underutilized management option to conserve evolutionary potential in a changing environment. This will be particularly true where advanced-generation hybrids exhibit adaptive traits outside the parental phenotypic range, a phenomenon known as transgressive segregation. The ideas presented in this essay are meant to provoke discussion regarding how we maintain evolutionary potential, the conservation value of natural hybrid zones, and consideration of their important role in adaptation to climate. © 2015 Society for Conservation Biology.

Biochemical and transcriptomic analyses reveal different metabolite biosynthesis profiles among three color and developmental stages in 'Anji Baicha' (Camellia sinensis).

PubMed

Li, Chun-Fang; Xu, Yan-Xia; Ma, Jian-Qiang; Jin, Ji-Qiang; Huang, Dan-Juan; Yao, Ming-Zhe; Ma, Chun-Lei; Chen, Liang

2016-09-08

The new shoots of the albino tea cultivar 'Anji Baicha' are yellow or white at low temperatures and turn green as the environmental temperatures increase during the early spring. 'Anji Baicha' metabolite profiles exhibit considerable variability over three color and developmental stages, especially regarding the carotenoid, chlorophyll, and theanine concentrations. Previous studies focused on physiological characteristics, gene expression differences, and variations in metabolite abundances in albino tea plant leaves at specific growth stages. However, the molecular mechanisms regulating metabolite biosynthesis in various color and developmental stages in albino tea leaves have not been fully characterized. We used RNA-sequencing to analyze 'Anji Baicha' leaves at the yellow-green, albescent, and re-greening stages. The leaf transcriptomes differed considerably among the three stages. Functional classifications based on Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes enrichment analyses revealed that differentially expressed unigenes were mainly related to metabolic pathways, biosynthesis of secondary metabolites, phenylpropanoid biosynthesis, and carbon fixation in photosynthetic organisms. Chemical analyses revealed higher β-carotene and theanine levels, but lower chlorophyll a levels, in the albescent stage than in the green stage. Furthermore, unigenes involved in carotenoid, chlorophyll, and theanine biosyntheses were identified, and the expression patterns of the differentially expressed unigenes in these biosynthesis pathways were characterized. Through co-expression analyses, we identified the key genes in these pathways. These genes may be responsible for the metabolite biosynthesis differences among the different leaf color and developmental stages of 'Anji Baicha' tea plants. Our study presents the results of transcriptomic and biochemical analyses of 'Anji Baicha' tea plants at various stages. The distinct transcriptome profiles for each color and developmental stage enabled us to identify changes to biosynthesis pathways and revealed the contributions of such variations to the albino phenotype of tea plants. Furthermore, comparisons of the transcriptomes and related metabolites helped clarify the molecular regulatory mechanisms underlying the secondary metabolic pathways in different stages.

Race, common genetic variation, and therapeutic response disparities in heart failure.

PubMed

Taylor, Mathew R; Sun, Albert Y; Davis, Gordon; Fiuzat, Mona; Liggett, Stephen B; Bristow, Michael R

2014-12-01

Because of its comparatively recent evolution, Homo sapiens exhibit relatively little within-species genomic diversity. However, because of genome size, a proportionately small amount of variation creates ample opportunities for both rare mutations that may cause disease as well as more common genetic variations that may be important in disease modification or pharmacogenetics. Primarily because of the East African origin of modern humans, individuals of African ancestry (AA) exhibit greater degrees of genetic diversity than more recently established populations, such as those of European ancestry (EA) or Asian ancestry. Those population effects extend to differences in frequency of common gene variants that may be important in heart failure natural history or therapy. For cell-signaling mechanisms important in heart failure, we review and present new data for genetic variation between AA and EA populations. Data indicate that: 1) neurohormonal signaling mechanisms frequently (16 of the 19 investigated polymorphisms) exhibit racial differences in the allele frequencies of variants comprising key constituents; 2) some of these differences in allele frequency may differentially affect the natural history of heart failure in AA compared with EA individuals; and 3) in many cases, these differences likely play a role in observed racial differences in drug or device response. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Cellular changes in the enteric nervous system during ageing.

PubMed

Saffrey, M Jill

2013-10-01

The intrinsic neurons of the gut, enteric neurons, have an essential role in gastrointestinal functions. The enteric nervous system is plastic and continues to undergo changes throughout life, as the gut grows and responds to dietary and other environmental changes. Detailed analysis of changes in the ENS during ageing suggests that enteric neurons are more vulnerable to age-related degeneration and cell death than neurons in other parts of the nervous system, although there is considerable variation in the extent and time course of age-related enteric neuronal loss reported in different studies. Specific neuronal subpopulations, particularly cholinergic myenteric neurons, may be more vulnerable than others to age-associated loss or damage. Enteric degeneration and other age-related neuronal changes may contribute to gastrointestinal dysfunction that is common in the elderly population. Evidence suggests that caloric restriction protects against age-associated loss of enteric neurons, but recent advances in the understanding of the effects of the microbiota and the complex interactions between enteric ganglion cells, mucosal immune system and intestinal epithelium indicate that other factors may well influence ageing of enteric neurons. Much remains to be understood about the mechanisms of neuronal loss and damage in the gut, although there is evidence that reactive oxygen species, neurotrophic factor dysregulation and/or activation of a senescence associated phenotype may be involved. To date, there is no evidence for ongoing neurogenesis that might replace dying neurons in the ageing gut, although small local sites of neurogenesis would be difficult to detect. Finally, despite the considerable evidence for enteric neurodegeneration during ageing, and evidence for some physiological changes in animal models, the ageing gut appears to maintain its function remarkably well in animals that exhibit major neuronal loss, indicating that the ENS has considerable functional reserve. © 2013 Elsevier Inc. All rights reserved.

Temperature-Dependent Sex Determination under Rapid Anthropogenic Environmental Change: Evolution at a Turtle's Pace?

PubMed

Refsnider, Jeanine M; Janzen, Fredric J

2016-01-01

Organisms become adapted to their environment by evolving through natural selection, a process that generally transpires over many generations. Currently, anthropogenically driven environmental changes are occurring orders of magnitude faster than they did prior to human influence, which could potentially outpace the ability of some organisms to adapt. Here, we focus on traits associated with temperature-dependent sex determination (TSD), a classic polyphenism, in a model turtle species to address the evolutionary potential of species with TSD to respond to rapid climate change. We show, first, that sex-ratio outcomes in species with TSD are sensitive to climatic variation. We then identify the evolutionary potential, in terms of heritability, of TSD and quantify the evolutionary potential of 3 key traits involved in TSD: pivotal temperature, maternal nest-site choice, and nesting phenology. We find that these traits display different patterns of adaptive potential: pivotal temperature exhibits moderate heritable variation, whereas nest-site choice and nesting phenology, with considerable phenotypic plasticity, have only modest evolutionary potential to alter sex ratios. Therefore, the most likely response of species with TSD to anthropogenically induced climate change may be a combination of microevolution in thermal sensitivity of the sex-determining pathway and of plasticity in maternal nesting behavior. © The American Genetic Association. 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Characterization of a gated fiber-optic-coupled detector for application in clinical electron beam dosimetry

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

Tanyi, James A.; Nitzling, Kevin D.; Lodwick, Camille J.

2011-02-15

Purpose: Assessment of the fundamental dosimetric characteristics of a novel gated fiber-optic-coupled dosimetry system for clinical electron beam irradiation. Methods: The response of fiber-optic-coupled dosimetry system to clinical electron beam, with nominal energy range of 6-20 MeV, was evaluated for reproducibility, linearity, and output dependence on dose rate, dose per pulse, energy, and field size. The validity of the detector system's response was assessed in correspondence with a reference ionization chamber. Results: The fiber-optic-coupled dosimetry system showed little dependence to dose rate variations (coefficient of variation {+-}0.37%) and dose per pulse changes (with 0.54% of reference chamber measurements). The reproducibilitymore » of the system was {+-}0.55% for dose fractions of {approx}100 cGy. Energy dependence was within {+-}1.67% relative to the reference ionization chamber for the 6-20 MeV nominal electron beam energy range. The system exhibited excellent linear response (R{sup 2}=1.000) compared to reference ionization chamber in the dose range of 1-1000 cGy. The output factors were within {+-}0.54% of the corresponding reference ionization chamber measurements. Conclusions: The dosimetric properties of the gated fiber-optic-coupled dosimetry system compare favorably to the corresponding reference ionization chamber measurements and show considerable potential for applications in clinical electron beam radiotherapy.« less

STATISTICAL CHARACTERISTICS OF ELEMENTAL ABUNDANCE RATIOS: OBSERVATIONS FROM THE ACE SPACECRAFT

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

Zhao, L.-L.; Zhang, H.

We statistically analyze the elemental galactic cosmic ray (GCR) composition measurements of elements 5 ≤ Z ≤ 28 within the energy range 30–500 MeV/nucleon from the CRIS instrument on board the ACE spacecraft in orbit about the L1 Lagrange point during the period from 1997 to 2014. Similarly to the last unusual solar minimum, the elevated elemental intensities of all heavy nuclei during the current weak solar maximum in 2014 are ∼40% higher than that of the previous solar maximum in 2002, which has been attributed to the weak modulation associated with low solar activity levels during the ongoing weakestmore » solar maximum since the dawn of space age. In addition, the abundance ratios of heavy nuclei with respect to elemental oxygen are generally independent of kinetic energy per nucleon in the energy region 60–200 MeV/nuc, in good agreement with previous experiments. Furthermore, the abundance ratios of most relatively abundant species, except carbon, exhibit considerable solar-cycle variation, which are obviously positively correlated with the sunspot numbers with about one-year time lag. We also find that the percentage variation of abundance ratios for most elements are approximately identical. These preliminary results provide valuable insights into the characteristics of elemental heavy nuclei composition and place new and significant constraints on future GCR heavy nuclei propagation and modulation models.« less

Genetic Correlates of Individual Differences in Sleep Behavior of Free-Living Great Tits (Parus major)

PubMed Central

Stuber, Erica F.; Baumgartner, Christine; Dingemanse, Niels J.; Kempenaers, Bart; Mueller, Jakob C.

2016-01-01

Within populations, free-living birds display considerable variation in observable sleep behaviors, reflecting dynamic interactions between individuals and their environment. Genes are expected to contribute to repeatable between-individual differences in sleep behaviors, which may be associated with individual fitness. We identified and genotyped polymorphisms in nine candidate genes for sleep, and measured five repeatable sleep behaviors in free-living great tits (Parus major), partly replicating a previous study in blue tits (Cyanistes caeruleus). Microsatellites in the CLOCK and NPAS2 clock genes exhibited an association with sleep duration relative to night length, and morning latency to exit the nest box, respectively. Furthermore, microsatellites in the NPSR1 and PCSK2 genes associated with relative sleep duration and proportion of time spent awake at night, respectively. Given the detection rate of associations in the same models run with random markers instead of candidate genes, we expected two associations to arise by chance. The detection of four associations between candidate genes and sleep, however, suggests that clock genes, a clock-related gene, or a gene involved in the melanocortin system, could play key roles in maintaining phenotypic variation in sleep behavior in avian populations. Knowledge of the genetic architecture underlying sleep behavior in the wild is important because it will enable ecologists to assess the evolution of sleep in response to selection. PMID:26739645

Population Genetic Structure and Colonisation History of the Tool-Using New Caledonian Crow

PubMed Central

Abdelkrim, Jawad; Hunt, Gavin R.; Gray, Russell D.; Gemmell, Neil J.

2012-01-01

New Caledonian crows exhibit considerable variation in tool making between populations. Here, we present the first study of the species’ genetic structure over its geographical distribution. We collected feathers from crows on mainland Grande Terre, the inshore island of Toupéti, and the nearby island of Maré where it is believed birds were introduced after European colonisation. We used nine microsatellite markers to establish the genotypes of 136 crows from these islands and classical population genetic tools as well as Approximate Bayesian Computations to explore the distribution of genetic diversity. We found that New Caledonian crows most likely separate into three main distinct clusters: Grande Terre, Toupéti and Maré. Furthermore, Toupéti and Maré crows represent a subset of the genetic diversity observed on Grande Terre, confirming their mainland origin. The genetic data are compatible with a colonisation of Maré taking place after European colonisation around 1900. Importantly, we observed (1) moderate, but significant, genetic differentiation across Grande Terre, and (2) that the degree of differentiation between populations on the mainland increases with geographic distance. These data indicate that despite individual crows’ potential ability to disperse over large distances, most gene flow occurs over short distances. The temporal and spatial patterns described provide a basis for further hypothesis testing and investigation of the geographical variation observed in the tool skills of these crows. PMID:22590576

Taxonomy of Individual Variations in Aesthetic Responses to Fractal Patterns

PubMed Central

Spehar, Branka; Walker, Nicholas; Taylor, Richard P.

2016-01-01

In two experiments, we investigate group and individual preferences in a range of different types of patterns with varying fractal-like scaling characteristics. In Experiment 1, we used 1/f filtered grayscale images as well as their thresholded (black and white) and edges only counterparts. Separate groups of observers viewed different types of images varying in slope of their amplitude spectra. Although with each image type, the groups exhibited the “universal” pattern of preference for intermediate amplitude spectrum slopes, we identified 4 distinct sub-groups in each case. Sub-group 1 exhibited a typical peak preference for intermediate amplitude spectrum slopes (“intermediate”; approx. 50%); sub-group 2 exhibited a linear increase in preference with increasing amplitude spectrum slope (“smooth”; approx. 20%), while sub-group 3 exhibited a linear decrease in preference as a function of the amplitude spectrum slope (“sharp”; approx. 20%). Sub-group 4 revealed no significant preference (“other”; approx. 10%). In Experiment 2, we extended the range of different image types and investigated preferences within the same observers. We replicate the results of our first experiment and show that individual participants exhibit stable patterns of preference across a wide range of image types. In both experiments, Q-mode factor analysis identified two principal factors that were able to explain more than 80% of interindividual variations in preference across all types of images, suggesting a highly similar dimensional structure of interindividual variations in preference for fractal-like scaling characteristics. PMID:27458365

Metabolomic profiling of the nectars of Aquilegia pubescens and A. canadensis

USDA-ARS?s Scientific Manuscript database

To date, variation in nectar chemistry of flowering plants has not been studied in detail. Such variation exerts considerable influence on pollinator–plant interactions, as well as on flower traits that play important roles in the selection of a plant for visitation by specific pollinators. Over the...

Genetic variation in domestic reindeer and wild caribou in Alaska

USGS Publications Warehouse

Cronin, M.; Renecker, L.; Pierson, Barbara J.; Patton, J.C.

1995-01-01

Reindeer were introduced into Alaska 100 years ago and have been maintained as semidomestic livestock. They have had contact with wild caribou herds, including deliberate cross-breeding and mixing in the wild. Reindeer have considerable potential as a domestic animal for meat or velvet antler production, and wild caribou are important to subsistence and sport hunters. Our objective was to quantify the genetic relationships of reindeer and caribou in Alaska. We identified allelic variation among five herds of wild caribou and three herds of reindeer with DNA sequencing and restriction enzymes for three loci: a DQA locus of the major histocompatibility complex (Rata-DQA1), k-casein and the D-loop of mitochondrial DNA. These loci are of interest because of their potential influence on domestic animal performance and the fitness of wild populations. There is considerable genetic variation in reindeer and caribou for all three loci, including five, three and six alleles for DQA, k-casein and D-loop respectively. Most alleles occur in both reindeer and caribou, which may be the result of recent common ancestry or genetic introgression in either direction. However, allele frequencies differ considerably between reindeer and caribou, which suggests that gene flow has been limited.

Population genomics reveals a candidate gene involved in bumble bee pigmentation.

PubMed

Pimsler, Meaghan L; Jackson, Jason M; Lozier, Jeffrey D

2017-05-01

Variation in bumble bee color patterns is well-documented within and between species. Identifying the genetic mechanisms underlying such variation may be useful in revealing evolutionary forces shaping rapid phenotypic diversification. The widespread North American species Bombus bifarius exhibits regional variation in abdominal color forms, ranging from red-banded to black-banded phenotypes and including geographically and phenotypically intermediate forms. Identifying genomic regions linked to this variation has been complicated by strong, near species level, genome-wide differentiation between red- and black-banded forms. Here, we instead focus on the closely related black-banded and intermediate forms that both belong to the subspecies B. bifarius nearcticus . We analyze an RNA sequencing (RNAseq) data set and identify a cluster of single nucleotide polymorphisms (SNPs) within one gene, Xanthine dehydrogenase/oxidase -like, that exhibit highly unusual differentiation compared to the rest of the sequenced genome. Homologs of this gene contribute to pigmentation in other insects, and results thus represent a strong candidate for investigating the genetic basis of pigment variation in B. bifarius and other bumble bee mimicry complexes.

Epigenetic contribution of the myosin light chain kinase gene to the risk for acute respiratory distress syndrome.

PubMed

Szilágyi, Keely L; Liu, Cong; Zhang, Xu; Wang, Ting; Fortman, Jeffrey D; Zhang, Wei; Garcia, Joe G N

2017-02-01

Acute respiratory distress syndrome (ARDS) is a devastating clinical syndrome with a considerable case fatality rate (∼30%-40%). Health disparities exist with African descent (AD) subjects exhibiting greater mortality than European descent (ED) individuals. Myosin light chain kinase is encoded by MYLK, whose genetic variants are implicated in ARDS pathogenesis and may influence ARDS mortality. As baseline population-specific epigenetic changes, that is, cytosine modifications, have been observed between AD and ED individuals, epigenetic variations in MYLK may provide insights into ARDS disparities. We compared methylation levels of MYLK cytosine-guanine dinucleotides (CpGs) between ARDS patients and intensive care unit (ICU) controls overall and by ethnicity in a nested case-control study of 39 ARDS cases and 75 non-ARDS ICU controls. Two MYLK CpG sites (cg03892735 and cg23344121) were differentially modified between ARDS subjects and controls (P < 0.05; q < 0.25) in a logistic regression model, where no effect modification by ethnicity or age was found. One CpG site was associated with ARDS in patients aged <58 years, cg19611163 (intron 19, 20). Two CpG sites were associated with ARDS in EDs only, gene body CpG (cg01894985, intron 2, 3) and CpG (cg16212219, intron 31, 32), with higher modification levels exhibited in ARDS subjects than controls. Cis-acting modified cytosine quantitative trait loci (mQTL) were identified using linear regression between local genetic variants and modification levels for 2 ARDS-associated CpGs (cg23344121 and cg16212219). In summary, these ARDS-associated MYLK CpGs with effect modification by ethnicity and local mQTL suggest that MYLK epigenetic variation and local genetic background may contribute to health disparities observed in ARDS. Copyright © 2016 Elsevier Inc. All rights reserved.

How Do People Become W.E.I.R.D.? Migration Reveals the Cultural Transmission Mechanisms Underlying Variation in Psychological Processes

PubMed Central

Mesoudi, Alex; Magid, Kesson; Hussain, Delwar

2016-01-01

Cultural psychologists have shown that people from Western, Educated, Industrialised, Rich, Democratic (WEIRD) countries often exhibit different psychological processing to people from less-WEIRD countries. The former exhibit more individualistic and less collectivistic social orientation, and more analytic and less holistic cognition, than non-Westerners. Yet the mechanisms responsible for maintaining this cultural variation are unclear. Immigration is an ideal ‘natural experiment’ for uncovering such mechanisms. We used a battery of psychological measures previously shown to vary cross-culturally to compare the social orientation and cognitive style of 286 residents of East London from three cultural backgrounds: (i) 1st-generation British Bangladeshi immigrants; (ii) 2nd-generation British Bangladeshis raised in the UK to Bangladeshi-raised parents; and (iii) non-migrants whose parents were born and raised in the UK. Model comparison revealed that individualism and dispositional attribution, typical of Western societies, are driven primarily by horizontal cultural transmission (e.g. via mass media), with parents and other family members having little or no effect, while collectivism, social closeness and situational attribution were driven by a mix of vertical/oblique cultural transmission (e.g. via family contact) and horizontal cultural transmission. These individual-level transmission dynamics can explain hitherto puzzling population-level phenomena, such as the partial acculturation of 2nd-generation immigrants on measures such as collectivism (due to the mix of vertical and horizontal cultural transmission), or the observation in several countries of increasing individualism (which is transmitted horizontally and therefore rapidly) despite little corresponding change in collectivism (which is transmitted partly vertically and therefore more slowly). Further consideration of cultural transmission mechanisms, in conjunction with the study of migrant communities and model comparison statistics, can shed light on the persistence of, and changes in, culturally-variable psychological processes. PMID:26760972

Microbial functional diversity plays an important role in the degradation of polyhydroxybutyrate (PHB) in soil.

PubMed

Dey, Samrat; Tribedi, Prosun

2018-03-01

Towards bioremediation of recalcitrant materials like synthetic polymer, soil has been recognized as a traditional site for disposal and subsequent degradation as some microorganisms in soil can degrade the polymer in a non-toxic, cost-effective, and environment friendly way. Microbial functional diversity is a constituent of biodiversity that includes wide range of metabolic activities that can influence numerous aspects of ecosystem functioning like ecosystem stability, nutrient availability, ecosystem dynamics, etc. Thus, in the current study, we assumed that microbial functional diversity could play an important role in polymer degradation in soil. To verify this hypothesis, we isolated soil from five different sites of landfill and examined several microbiological parameters wherein we observed a significant variation in heterotrophic microbial count as well as microbial activities among the soil microcosms tested. Multivariate analysis (principle component analysis) based on the carbon sources utilization pattern revealed that soil microcosms showed different metabolic patterns suggesting the variable distribution of microorganisms among the soil microcosms tested. Since microbial functional diversity depends on both microbial richness and evenness, Shannon diversity index was determined to measure microbial richness and Gini coefficient was determined to measure microbial evenness. The tested soil microcosms exhibited variation in both microbial richness and evenness suggesting the considerable difference in microbial functional diversity among the tested microcosms. We then measured polyhydroxybutyrate (PHB) degradation in soil microcosms after desired period of incubation of PHB in soil wherein we found that soil microcosms having higher functional diversity showed enhanced PHB degradation and soil microcosms having lower functional diversity showed reduced PHB degradation. We also noticed that all the tested soil microcosms showed similar pattern in both microbial functional diversity and PHB degradation suggesting a strong positive correlation ( r  = 0.95) between microbial functional diversity and PHB degradation. Thus, the results demonstrate that microbial functional diversity plays an important role in PHB degradation in soil by exhibiting versatile microbial metabolic potentials that lead to the enhanced degradation of PHB.

Resilience to temperature and pH changes in a future climate change scenario in six strains of the polar diatom Fragilariopsis cylindrus

NASA Astrophysics Data System (ADS)

Pančić, M.; Hansen, P. J.; Tammilehto, A.; Lundholm, N.

2015-07-01

The effects of ocean acidification and increased temperature on physiology of six strains of the polar diatom Fragilariopsis cylindrus from Greenland were investigated. Experiments were performed under manipulated pH levels (8.0, 7.7, 7.4, and 7.1) and different temperatures (1, 5, and 8 °C) to simulate changes from present to plausible future levels. Each of the 12 scenarios was run for 7 days, and a significant interaction between temperature and pH on growth was detected. By combining increased temperature and acidification, the two factors counterbalanced each other, and therefore no effect on the growth rates was found. However, the growth rates increased with elevated temperatures by ~ 20-50 % depending on the strain. In addition, a general negative effect of increasing acidification on growth was observed. At pH 7.7 and 7.4, the growth response varied considerably among strains. However, a more uniform response was detected at pH 7.1 with most of the strains exhibiting reduced growth rates by 20-37 % compared to pH 8.0. It should be emphasized that a significant interaction between temperature and pH was found, meaning that the combination of the two parameters affected growth differently than when considering one at a time. Based on these results, we anticipate that the polar diatom F. cylindrus will be unaffected by changes in temperature and pH within the range expected by the end of the century. In each simulated scenario, the variation in growth rates among the strains was larger than the variation observed due to the whole range of changes in either pH or temperature. Climate change may therefore not affect the species as such, but may lead to changes in the population structure of the species, with the strains exhibiting high phenotypic plasticity, in terms of temperature and pH tolerance towards future conditions, dominating the population.

Resilience to temperature and pH changes in a future climate change scenario in six strains of the polar diatom Fragilariopsis cylindrus

NASA Astrophysics Data System (ADS)

Pančić, M.; Hansen, P. J.; Tammilehto, A.; Lundholm, N.

2015-03-01

The effects of ocean acidification and increased temperature on physiology of six strains of the polar diatom Fragilariopsis cylindrus from Greenland were investigated. Experiments were performed under manipulated pH levels (8.0, 7.7, 7.4, and 7.1) and different temperatures (1, 5 and 8 °C) to simulate changes from present to plausible future levels. Each of the 12 scenarios was run for 7 days, and a significant interaction between temperature and pH on growth was detected. By combining increased temperature and acidification, the two factors counterbalanced each other, and therefore no effect on the growth rates was found. However, the growth rates increased with elevated temperatures by ∼20-50% depending on the strain. In addition, a general negative effect of increasing acidification on growth was observed. At pH 7.7 and 7.4, the growth response varied considerably among strains. However, a more uniform response was detected at pH 7.1 with most of the strains exhibiting reduced growth rates by 20-37% compared to pH 8.0. It should be emphasized that a significant interaction between temperature and pH was found, meaning that the combination of the two parameters affected growth differently than when considering one at a time. Based on these results, we anticipate that the polar diatom F. cylindrus will be unaffected by changes in temperature and pH within the range expected by the end of the century. In each simulated scenario, the variation in growth rates among the strains was larger than the variation observed due to the whole range of changes in either pH or temperature. Climate change may therefore not affect the species as such, but may lead to changes in the population structure of the species, with the strains exhibiting high phenotypic plasticity, in terms of temperature and pH tolerance towards future conditions, dominating the population.

Inconsistencies of interannual variability and trends in long-term satellite leaf area index products.

PubMed

Jiang, Chongya; Ryu, Youngryel; Fang, Hongliang; Myneni, Ranga; Claverie, Martin; Zhu, Zaichun

2017-10-01

Understanding the long-term performance of global satellite leaf area index (LAI) products is important for global change research. However, few effort has been devoted to evaluating the long-term time-series consistencies of LAI products. This study compared four long-term LAI products (GLASS, GLOBMAP, LAI3g, and TCDR) in terms of trends, interannual variabilities, and uncertainty variations from 1982 through 2011. This study also used four ancillary LAI products (GEOV1, MERIS, MODIS C5, and MODIS C6) from 2003 through 2011 to help clarify the performances of the four long-term LAI products. In general, there were marked discrepancies between the four long-term LAI products. During the pre-MODIS period (1982-1999), both linear trends and interannual variabilities of global mean LAI followed the order GLASS>LAI3g>TCDR>GLOBMAP. The GLASS linear trend and interannual variability were almost 4.5 times those of GLOBMAP. During the overlap period (2003-2011), GLASS and GLOBMAP exhibited a decreasing trend, TCDR no trend, and LAI3g an increasing trend. GEOV1, MERIS, and MODIS C6 also exhibited an increasing trend, but to a much smaller extent than that from LAI3g. During both periods, the R 2 of detrended anomalies between the four long-term LAI products was smaller than 0.4 for most regions. Interannual variabilities of the four long-term LAI products were considerably different over the two periods, and the differences followed the order GLASS>LAI3g>TCDR>GLOBMAP. Uncertainty variations quantified by a collocation error model followed the same order. Our results indicate that the four long-term LAI products were neither intraconsistent over time nor interconsistent with each other. These inconsistencies may be due to NOAA satellite orbit changes and MODIS sensor degradation. Caution should be used in the interpretation of global changes derived from the four long-term LAI products. © 2017 John Wiley & Sons Ltd.

Ecological correlates of mate fidelity in two Arctic-breeding sandpipers

USGS Publications Warehouse

Sandercock, Brett K.; Lank, David B.; Lanctot, Richard B.; Kempenaers, Bart; Cooke, Fred

2000-01-01

Monogamous birds exhibit considerable interspecific variation in rates of mate fidelity between years, but the reasons for this variation are still poorly understood. In a 4-year study carried out in western Alaska, mate-fidelity rates in Semipalmated Sandpipers (Calidris pusilla; mate fidelity was 47% among pairs where at least one mate returned and 94% among pairs where both mates returned) were substantially higher than in Western Sandpipers (Calidris mauri; 25 and 67%, respectively), despite the similar breeding biology of these sibling species. Divorce was not a response to nesting failure in Western Sandpipers, and mate change had no effect on the reproductive performance of either species. Nor were mate-fidelity rates related to differential rates of breeding dispersal, because the species did not differ in site fidelity. Reunited pairs and males that changed mates showed strong site tenacity, while females that changed mates moved farther. Differences in local survival rates or habitat are also unlikely to explain mate fidelity, since the two species did not differ in local survival rates, ϕ (Western Sandpipers: ϕ –hat = 0.57 ± 0.05 (mean ± SE), Semipalmated Sandpipers: ϕ –hat = 0.66 ± 0.06), and they bred in the same area, sometimes using the same nest cups. Although we were able to reject the above explanations, it was not possible to determine whether mate retention was lower in Western Sandpipers than in Semipalmated Sandpipers because of interspecific differences in mating tactics, time constraints imposed by migration distance, or a combination of these factors. Western Sandpipers exhibited greater sexual size dimorphism, but also migrated for shorter distances and tended to nest earlier and more asynchronously than Semipalmated Sandpipers. Finally, we show that conventional methods underestimate divorce rates, and interspecific comparisons may be biased if breeding-dispersal and recapture rates are not considered.

How Do People Become W.E.I.R.D.? Migration Reveals the Cultural Transmission Mechanisms Underlying Variation in Psychological Processes.

PubMed

Mesoudi, Alex; Magid, Kesson; Hussain, Delwar

2016-01-01

Cultural psychologists have shown that people from Western, Educated, Industrialised, Rich, Democratic (WEIRD) countries often exhibit different psychological processing to people from less-WEIRD countries. The former exhibit more individualistic and less collectivistic social orientation, and more analytic and less holistic cognition, than non-Westerners. Yet the mechanisms responsible for maintaining this cultural variation are unclear. Immigration is an ideal 'natural experiment' for uncovering such mechanisms. We used a battery of psychological measures previously shown to vary cross-culturally to compare the social orientation and cognitive style of 286 residents of East London from three cultural backgrounds: (i) 1st-generation British Bangladeshi immigrants; (ii) 2nd-generation British Bangladeshis raised in the UK to Bangladeshi-raised parents; and (iii) non-migrants whose parents were born and raised in the UK. Model comparison revealed that individualism and dispositional attribution, typical of Western societies, are driven primarily by horizontal cultural transmission (e.g. via mass media), with parents and other family members having little or no effect, while collectivism, social closeness and situational attribution were driven by a mix of vertical/oblique cultural transmission (e.g. via family contact) and horizontal cultural transmission. These individual-level transmission dynamics can explain hitherto puzzling population-level phenomena, such as the partial acculturation of 2nd-generation immigrants on measures such as collectivism (due to the mix of vertical and horizontal cultural transmission), or the observation in several countries of increasing individualism (which is transmitted horizontally and therefore rapidly) despite little corresponding change in collectivism (which is transmitted partly vertically and therefore more slowly). Further consideration of cultural transmission mechanisms, in conjunction with the study of migrant communities and model comparison statistics, can shed light on the persistence of, and changes in, culturally-variable psychological processes.

Genetic improvement of disease resistance in salmonid fish using selective breeding: Overview of concepts, considerations and limitations

USDA-ARS?s Scientific Manuscript database

In aquaculture, endemic infectious diseases constitute a considerable economic burden due to direct losses as well as indirect impacts on growth and animal welfare. In response to infectious disease, it is well documented that host genetic variation is present in most animal populations, especially ...

Determinants of Awareness, Consideration, and Choice Set Size in University Choice.

ERIC Educational Resources Information Center

Dawes, Philip L.; Brown, Jennifer

2002-01-01

Developed and tested a model of students' university "brand" choice using five individual-level variables (ethnic group, age, gender, number of parents going to university, and academic ability) and one situational variable (duration of search) to explain variation in the sizes of awareness, consideration, and choice decision sets. (EV)

When things go pear shaped: contour variations of contacts

NASA Astrophysics Data System (ADS)

Utzny, Clemens

2013-04-01

Traditional control of critical dimensions (CD) on photolithographic masks considers the CD average and a measure for the CD variation such as the CD range or the standard deviation. Also systematic CD deviations from the mean such as CD signatures are subject to the control. These measures are valid for mask quality verification as long as patterns across a mask exhibit only size variations and no shape variation. The issue of shape variations becomes especially important in the context of contact holes on EUV masks. For EUV masks the CD error budget is much smaller than for standard optical masks. This means that small deviations from the contact shape can impact EUV waver prints in the sense that contact shape deformations induce asymmetric bridging phenomena. In this paper we present a detailed study of contact shape variations based on regular product data. Two data sets are analyzed: 1) contacts of varying target size and 2) a regularly spaced field of contacts. Here, the methods of statistical shape analysis are used to analyze CD SEM generated contour data. We demonstrate that contacts on photolithographic masks do not only show size variations but exhibit also pronounced nontrivial shape variations. In our data sets we find pronounced shape variations which can be interpreted as asymmetrical shape squeezing and contact rounding. Thus we demonstrate the limitations of classic CD measures for describing the feature variations on masks. Furthermore we show how the methods of statistical shape analysis can be used for quantifying the contour variations thus paving the way to a new understanding of mask linearity and its specification.

Diurnal variation in ruminal pH on the digestibility of highly digestible perennial ryegrass during continuous culture fermentation.

PubMed

Wales, W J; Kolver, E S; Thorne, P L; Egan, A R

2004-06-01

Dairy cows grazing high-digestibility pastures exhibit pronounced diurnal variation in ruminal pH, with pH being below values considered optimal for digestion. Using a dual-flow continuous culture system, the hypothesis that minimizing diurnal variation in pH would improve digestion of pasture when pH was low, but not at a higher pH, was tested. Four treatments were imposed, with pH either allowed to exhibit normal diurnal variation around an average pH of 6.1 or 5.6, or maintained at constant pH. Digesta samples were collected during the last 3 d of each of four, 9-d experimental periods. A constant pH at 5.6 compared with a constant pH of 6.1 reduced the digestibility of organic matter (OM), neutral detergent (NDF), and acid detergent fiber (ADF) by 7, 14, and 21%, respectively. When pH was allowed to vary (averaging 5.6), digestion of OM, NDF, and ADF were reduced by 15,30, and 36%, respectively, compared with pH varying at 6.1. There was little difference in digestion parameters when pH was either constant or varied with an average pH of 6.1. However, when average pH was 5.6, maintaining a constant pH significantly increased digestion of OM, NDF, and ADF by 5, 25, and 24% compared with a pH that exhibited normal diurnal variation. These in vitro results show that gains in digestibility and potential milk production can be made by minimizing diurnal variation in ruminal pH, but only when ruminal pH is low (5.6). However, larger gains in productivity can be achieved by increasing average daily ruminal pH from 5.6 to 6.1.

Sulfation of melatonin: enzymatic characterization, differences of organs, species and genders, and bioactivity variation.

PubMed

Tian, Xiangge; Huo, Xiaokui; Dong, Peipei; Wu, Baojian; Wang, Xiaobo; Wang, Chao; Liu, Kexin; Ma, Xiaochi

2015-04-15

Exogenous melatonin (Mel) is widely used in clinic for multiple therapeutic purposes. In metabolism pathways of Mel, 6-hydroxymelatonin-sulfate (S-O-Mel) and N-acetylserotonin sulfate (S-NAS) are the most abundant metabolites account for over 90% of total Mel metabolites in humans, indicating that sulfation plays an important role in reflecting the functions and clearance of Mel in vivo. In the present study, we characterized Mel sulfation using various human organ cytosols (liver, lung, kidney, small intestine and brain), liver cytosols from five different animal species, and cDNA-expressed human sulfotransferase (SULT) for the first time. Our results demonstrated that liver, lung, kidney and small intestine of humans had high catalytic efficiency for Mel sulfation, however, brain contained a very low reaction rate. Interestingly, organ cytosols prepared from females exhibited higher sulfation activity than those of males. SULT isoforms 1A1, 1A2, 1A3, 1B1 and 1E1 exhibited metabolic activities toward Mel. According to kinetic parameters (Km and Vmax), chemical inhibition, correlation analysis, molecular docking and sulfation assays with recombinant human SULTs isoforms, SULT1A1 was determined as the major enzyme responsible for Mel sulfation. Furthermore, considerable species differences in Mel sulfation were observed, and the total intrinsic clearance rate of Mel sulfation was as follows: monkey>rat>dog>human>pig>mouse. Additionally, the anti-inflammatory effects of Mel and its sulfated metabolites were evaluated by inhibiting nitric oxide (NO) production in RAW264.7 cells, and S-O-Mel as a bioactive form, exhibited potent bioactivity. Our investigation provided a global view of the enzyme-dependent sulfation of Mel that can guide biomedical research on Mel. Copyright © 2015 Elsevier Inc. All rights reserved.

Effects of body condition on buoyancy in endangered North Atlantic right whales.

PubMed

Nousek-McGregor, Anna E; Miller, Carolyn A; Moore, Michael J; Nowacek, Douglas P

2014-01-01

Buoyancy is an important consideration for diving marine animals, resulting in specific ecologically relevant adaptations. Marine mammals use blubber as an energy reserve, but because this tissue is also positively buoyant, nutritional demands have the potential to cause considerable variation in buoyancy. North Atlantic right whales Eubalaena glacialis are known to be positively buoyant as a result of their blubber, and the thickness of this layer varies considerably, but the effect of this variation on buoyancy has not been explored. This study compared the duration and rate of ascending and descending glides, recorded with an archival tag, with blubber thickness, measured with an ultrasound device, in free-swimming right whales. Ascending whales with thicker blubber had shorter portions of active propulsion and longer passive glides than whales with thinner blubber, suggesting that blubber thickness influences buoyancy because the buoyant force is acting in the same direction as the animal's movement during this phase. Whales with thinner layers also used similar body angles and velocities when traveling to and from depth, while those with thicker layers used shallower ascent angles but achieved higher ascent velocities. Such alterations in body angle may help to reduce the cost of transport when swimming against the force of buoyancy in a state of augmented positive buoyancy, which represents a dynamic response to reduce the energetic consequences of physiological changes. These results have considerable implications for any diving marine animal during periods of nutritional stress, such as during seasonal migrations and annual variations in prey availability.

A study of vertebra number in pigs confirms the association of vertnin and reveals additional QTL

USDA-ARS?s Scientific Manuscript database

Background: Formation of the vertebral column is a critical developmental stage in mammals. The strict control of this process has resulted in little variation in number of vertebrae across mammalian species and no variation within most mammalian species. The pig is quite unique as considerable vari...

Variations in Pedagogical Design of Massive Open Online Courses (MOOCs) across Disciplines

ERIC Educational Resources Information Center

Najafi, Hadieh; Rolheiser, Carol; Håklev, Stian; Harrison, Laurie

2017-01-01

Given that few studies have formally examined pedagogical design considerations of Massive Online Open Courses (MOOCs), this study explored variations in the pedagogical design of six MOOCs offered at the University of Toronto, while considering disciplinary characteristics and expectations of each MOOC. Using a framework (Neumann et al., 2002)…

Self-Study and Evaluation Guide; Section C-2; Financial Accounting and Service Reporting.

ERIC Educational Resources Information Center

National Accreditation Council for Agencies Serving the Blind and Visually Handicapped, New York, NY.

In determining standards to judge an agency's performance in meeting its responsibilities to the public, two fundamental factors must be taken into consideration: (1) standards for financial accounting and service reporting must be formulated in the knowledge that variations among agencies will necessarily give rise to variations in applicability…

Adjustment of relative humidity and temperature for differences in elevation.

Treesearch

Owen P. Cramer

1961-01-01

The variation of fire-weather elements in mountainous terrain is complex at any one time, and the patterns vary considerably with time. During periods of serious fire weather, this variation becomes important. Much information is obtainable by local interpretation of available forecasts and observations. Optimum use of available information requires some understanding...

Height growth of ponderosa pine progenies

Treesearch

R. Z. Callaham; A. A. Hasel

1957-01-01

Research at the Institute of Forest Genetics at Plaeerville, California since its inception in 1925, has been concerned with the variation in individual trees of a speices. We are interested in this variation as a guide to selection of outstanding individuals. Western forests have considerable diversity in soils, topography, species composition, and distribution of age...

Family losses following truncation selection in populations of half-sib families

Treesearch

J. H. Roberds; G. Namkoong; H. Kang

1980-01-01

Family losses during truncation selection may be sizable in populations of half-sib families. Substantial losses may occur even in populations containing little or no variation among families. Heavier losses will occur, however, under conditions of high heritability where there is considerable family variation. Standard deviations and therefore variances of family loss...

High-resolution photography of clouds from the surface: Retrieval of optical depth of thin clouds down to centimeter scales: High-Resolution Photography of Clouds

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

Schwartz, Stephen E.; Huang, Dong; Vladutescu, Daniela Viviana

This article describes the approach and presents initial results, for a period of several minutes in north central Oklahoma, of an examination of clouds by high resolution digital photography from the surface looking vertically upward. A commercially available camera having 35-mm equivalent focal length up to 1200 mm (nominal resolution as fine as 6 µrad, which corresponds to 9 mm for cloud height 1.5 km) is used to obtain a measure of zenith radiance of a 30 m × 30 m domain as a two-dimensional image consisting of 3456 × 3456 pixels (12 million pixels). Downwelling zenith radiance varies substantiallymore » within single images and between successive images obtained at 4-s intervals. Variation in zenith radiance found on scales down to about 10 cm is attributed to variation in cloud optical depth (COD). Attention here is directed primarily to optically thin clouds, COD less than about 2. A radiation transfer model used to relate downwelling zenith radiance to COD and to relate the counts in the camera image to zenith radiance, permits determination of COD on a pixel-by-pixel basis. COD for thin clouds determined in this way exhibits considerable variation, for example, an order of magnitude within 15 m, a factor of 2 within 4 m, and 25% (0.12 to 0.15) over 14 cm. In conclusion, this approach, which examines cloud structure on scales 3 to 5 orders of magnitude finer than satellite products, opens new avenues for examination of cloud structure and evolution.« less

Seismic Wave Propagation in Fully Anisotropic Axisymmetric Media: Applications and Practical Considerations

NASA Astrophysics Data System (ADS)

van Driel, Martin; Nissen-Meyer, Tarje; Stähler, Simon; Waszek, Lauren; Hempel, Stefanie; Auer, Ludwig; Deuss, Arwen

2014-05-01

We present a numerical method to compute high-frequency 3D elastic waves in fully anisotropic axisymmetric media. The method is based on a decomposition of the wavefield into a series of uncoupled 2D equations, for which the dependence of the wavefield on the azimuth can be solved analytically. The remaining 2D problems are then solved using a spectral element method (AxiSEM). AxiSEM was recently published open-source (Nissen-Meyer et al. 2014) as a production ready code capable to compute global seismic wave propagation up to frequencies of ~2Hz. It accurately models visco-elastic dissipation and anisotropy (van Driel et al., submitted to GJI) and runs efficiently on HPC resources using up to 10K cores. At very short period, the Fresnel Zone of body waves is narrow and sensitivity is focused around the geometrical ray. In cases where the azimuthal variations of structural heterogeneity exhibit long spatial wavelengths, so called 2.5D simulations (3D wavefields in 2D models) provide a good approximation. In AxiSEM, twodimensional variations in the source-receiver plane are effectively modelled as ringlike structures extending in the out-of-plane direction. In contrast to ray-theory, which is widely used in high-frequency applications, AxiSEM provides complete waveforms, thus giving access to frequency dependency, amplitude variations, and peculiar wave effects such as diffraction and caustics. Here we focus on the practical implications of the inherent axisymmetric geometry and show how the 2.5D-features of our method method can be used to model realistic anisotropic structures, by applying it to problems such as the D" region and the inner core.

High-resolution photography of clouds from the surface: Retrieval of optical depth of thin clouds down to centimeter scales: High-Resolution Photography of Clouds

DOE PAGES

Schwartz, Stephen E.; Huang, Dong; Vladutescu, Daniela Viviana

2017-03-08

This article describes the approach and presents initial results, for a period of several minutes in north central Oklahoma, of an examination of clouds by high resolution digital photography from the surface looking vertically upward. A commercially available camera having 35-mm equivalent focal length up to 1200 mm (nominal resolution as fine as 6 µrad, which corresponds to 9 mm for cloud height 1.5 km) is used to obtain a measure of zenith radiance of a 30 m × 30 m domain as a two-dimensional image consisting of 3456 × 3456 pixels (12 million pixels). Downwelling zenith radiance varies substantiallymore » within single images and between successive images obtained at 4-s intervals. Variation in zenith radiance found on scales down to about 10 cm is attributed to variation in cloud optical depth (COD). Attention here is directed primarily to optically thin clouds, COD less than about 2. A radiation transfer model used to relate downwelling zenith radiance to COD and to relate the counts in the camera image to zenith radiance, permits determination of COD on a pixel-by-pixel basis. COD for thin clouds determined in this way exhibits considerable variation, for example, an order of magnitude within 15 m, a factor of 2 within 4 m, and 25% (0.12 to 0.15) over 14 cm. In conclusion, this approach, which examines cloud structure on scales 3 to 5 orders of magnitude finer than satellite products, opens new avenues for examination of cloud structure and evolution.« less

Critical Value Reporting at Egyptian Laboratories.

PubMed

Mosallam, Rasha; Ibrahim, Samaa Zenhom

2015-06-12

To examine critical value reporting policies and practices and to identify critical value ranges for selected common laboratory assays at inpatient division of laboratories of Alexandria hospitals. A cross-sectional descriptive study design was used. Subjects were from inpatient division of all laboratories of Alexandria hospitals (40 laboratories). Data were collected using a questionnaire composed of 4 sections. The first section explored hospital and laboratory characteristics. The second section assessed policies and procedures of critical value reporting. The third section explored the reporting process. The fourth section explored critical value ranges for selected common laboratory assays. Written procedure for reporting of critical values was present in 77.5% of laboratories and a comprehensive list of critical values in 72.55%. For laboratories having a critical value list, the number of tests in the list ranged from 7 to 40. Three-fifths of laboratories had a policy for assessing the timeliness of reporting and 3 quarters stated that the laboratory policy requires feedback (60.0% and 75.0%, respectively). The hospital laboratory physician was responsible for critical value reporting followed by the laboratory technician (75.0% and 50.0%, respectively). The call is received mainly by nurses and physicians ordering the test (67.5% and 55.0%, respectively) and the channel of reporting is mainly the telephone or through sending test report to the ward (67.5% and 50.0%, respectively). Wireless technologies are used in reporting in only 10.0% of hospitals. The cutoff limits for reporting different assays showed considerable interlaboratory variation. Critical value policies and practices showed interinstitutional variation with deficiencies in some reporting practices. Selection of critical assays for notification and setting the limits of notification exhibited wide variation as well.

Superhydrophilic TiO2 thin film by nanometer scale surface roughness and dangling bonds

NASA Astrophysics Data System (ADS)

Bharti, Bandna; Kumar, Santosh; Kumar, Rajesh

2016-02-01

A remarkable enhancement in the hydrophilic nature of titanium dioxide (TiO2) films is obtained by surface modification in DC-glow discharge plasma. Thin transparent TiO2 films were coated on glass substrate by sol-gel dip coating method, and exposed in DC-glow discharge plasma. The plasma exposed TiO2 film exhibited a significant change in its wetting property contact angle, which is a representative of wetting property, has reduced to considerable limits 3.02° and 1.85° from its initial value 54.40° and 48.82° for deionized water and ethylene glycol, respectively. It is elucidated that the hydrophilic property of plasma exposed TiO2 films dependent mainly upon nanometer scale surface roughness. Variation, from 4.6 nm to 19.8 nm, in the film surface roughness with exposure time was observed by atomic force microscopy (AFM). Analysis of variation in the values of contact angle and surface roughness with increasing plasma exposure time reveal that the surface roughness is the main factor which makes the modified TiO2 film superhydrophilic. However, a contribution of change in the surface states, to the hydrophilic property, is also observed for small values of the plasma exposure time. Based upon nanometer scale surface roughness and dangling bonds, a variation in the surface energy of TiO2 film from 49.38 to 88.92 mJ/m2 is also observed. X-ray photoelectron spectroscopy (XPS) results show change in the surface states of titanium and oxygen. The observed antifogging properties are the direct results of the development of the superhydrophilic wetting characteristics to TiO2 films.

Assessment of total and organic vanadium levels and their bioaccumulation in edible sea cucumbers: tissues distribution, inter-species-specific, locational differences and seasonal variations.

PubMed

Liu, Yanjun; Zhou, Qingxin; Xu, Jie; Xue, Yong; Liu, Xiaofang; Wang, Jingfeng; Xue, Changhu

2016-02-01

The objective of this study is to investigate the levels, inter-species-specific, locational differences and seasonal variations of vanadium in sea cucumbers and to validate further several potential factors controlling the distribution of metals in sea cucumbers. Vanadium levels were evaluated in samples of edible sea cucumbers and were demonstrated exhibit differences in different seasons, species and sampling sites. High vanadium concentrations were measured in the sea cucumbers, and all of the vanadium detected was in an organic form. Mean vanadium concentrations were considerably higher in the blood (sea cucumber) than in the other studied tissues. The highest concentration of vanadium (2.56 μg g(-1)), as well as a higher degree of organic vanadium (85.5 %), was observed in the Holothuria scabra samples compared with all other samples. Vanadium levels in Apostichopus japonicus from Bohai Bay and Yellow Sea have marked seasonal variations. Average values of 1.09 μg g(-1) of total vanadium and 0.79 μg g(-1) of organic vanadium were obtained in various species of sea cucumbers. Significant positive correlations between vanadium in the seawater and V org in the sea cucumber (r = 81.67 %, p = 0.00), as well as between vanadium in the sediment and V org in the sea cucumber (r = 77.98 %, p = 0.00), were observed. Vanadium concentrations depend on the seasons (salinity, temperature), species, sampling sites and seawater environment (seawater, sediment). Given the adverse toxicological effects of inorganic vanadium and positive roles in controlling the development of diabetes in humans, a regular monitoring programme of vanadium content in edible sea cucumbers can be recommended.

Gene network polymorphism is the raw material of natural selection: the selfish gene network hypothesis.

PubMed

Boldogköi, Zsolt

2004-09-01

Population genetics, the mathematical theory of modern evolutionary biology, defines evolution as the alteration of the frequency of distinct gene variants (alleles) differing in fitness over the time. The major problem with this view is that in gene and protein sequences we can find little evidence concerning the molecular basis of phenotypic variance, especially those that would confer adaptive benefit to the bearers. Some novel data, however, suggest that a large amount of genetic variation exists in the regulatory region of genes within populations. In addition, comparison of homologous DNA sequences of various species shows that evolution appears to depend more strongly on gene expression than on the genes themselves. Furthermore, it has been demonstrated in several systems that genes form functional networks, whose products exhibit interrelated expression profiles. Finally, it has been found that regulatory circuits of development behave as evolutionary units. These data demonstrate that our view of evolution calls for a new synthesis. In this article I propose a novel concept, termed the selfish gene network hypothesis, which is based on an overall consideration of the above findings. The major statements of this hypothesis are as follows. (1) Instead of individual genes, gene networks (GNs) are responsible for the determination of traits and behaviors. (2) The primary source of microevolution is the intraspecific polymorphism in GNs and not the allelic variation in either the coding or the regulatory sequences of individual genes. (3) GN polymorphism is generated by the variation in the regulatory regions of the component genes and not by the variance in their coding sequences. (4) Evolution proceeds through continuous restructuring of the composition of GNs rather than fixing of specific alleles or GN variants.

Melanocortin receptor 1 and black pigmentation in the Japanese ornamental carp (Cyprinus carpio var. Koi).

PubMed

Bar, Ido; Kaddar, Ethan; Velan, Ariel; David, Lior

2013-01-01

Colors and their patterns are fascinating phenotypes with great importance for fitness under natural conditions. For this reason and because pigmentation is associated with diseases, much research was devoted to study the genetics of pigmentation in animals. Considerable contribution to our understanding of color phenotypes was made by studies in domesticated animals that exhibit dazzling variation in color traits. Koi strains, the ornamental variants of the common carp, are a striking example for color variability that was selected by man during a very short period on an evolutionary timescale. Among several pigmentation genes, genetic variation in Melanocrtin receptor 1 was repeatedly associated with dark pigmentation phenotypes in numerous animals. In this study, we cloned Melanocrtin receptor 1 from the common carp. We found that alleles of the gene were not associated with the development of black color in Koi. However, the mRNA expression levels of the gene were higher during dark pigmentation development in larvae and in dark pigmented tissues of adult fish, suggesting that variation in the regulation of the gene is associated with black color in Koi. These regulatory differences are reflected in both the timing of the dark-pigmentation development and the different mode of inheritance of the two black patterns associated with them. Identifying the genetic basis of color and color patterns in Koi will promote the production of this valuable ornamental fish. Furthermore, given the rich variety of colors and patterns, Koi serves as a good model to unravel pigmentation genes and their phenotypic effects and by that to improve our understanding of the genetic basis of colors also in natural populations.

Constancy despite variability: Local and regional macrofaunal diversity in intertidal seagrass beds

NASA Astrophysics Data System (ADS)

Boyé, Aurélien; Legendre, Pierre; Grall, Jacques; Gauthier, Olivier

2017-12-01

The importance of seagrass habitat for the diversity of benthic fauna has been extensively studied worldwide. Most of the information available is, however, about α diversity while little consideration has been given to β diversity. To fill the knowledge gaps regarding the variability of epifaunal and infaunal seagrass assemblages at large spatial and temporal scales, we scrutinized an extensive dataset covering five years of monitoring of eight intertidal Zostera marina meadows around Brittany (France). High species richness arose at the regional scale from the combination of high local diversity of the meadows and substantial among-meadows β diversity. Epifauna and infauna appeared as distinct self-communities as they displayed different spatial and temporal patterns and varied in their responses to local hydrological conditions. Infauna had higher total β diversity than epifauna due to a tighter link to the great variability of local environmental conditions in the region. Both exhibited substantial variations in species composition and community structure with variations of dominant species that were accompanied by extensive change in numerous rare species. The dominant epifaunal species were all grazers. Changes in species composition were induced mostly by species replacement and rarely by richness differences between meadows. Indeed, species richness remained within a narrow range for all seagrass beds, suggesting a potential carrying capacity for species richness of the meadows. Overall, all meadows contributed equally to the regional turnover of seagrass macrofauna, emphasizing high variability and complementarity among beds at the regional scale. The implications of this substantial within-seagrass variability for the functioning of benthic ecosystems at broad scale and for conservation purposes in habitat mosaics warrant further investigations but our results clearly advocate taking into account within-habitat variation when evaluating the diversity of benthic habitats and the potential effect of habitat loss.

Melanocortin receptor 1 and black pigmentation in the Japanese ornamental carp (Cyprinus carpio var. Koi)

PubMed Central

Bar, Ido; Kaddar, Ethan; Velan, Ariel; David, Lior

2013-01-01

Colors and their patterns are fascinating phenotypes with great importance for fitness under natural conditions. For this reason and because pigmentation is associated with diseases, much research was devoted to study the genetics of pigmentation in animals. Considerable contribution to our understanding of color phenotypes was made by studies in domesticated animals that exhibit dazzling variation in color traits. Koi strains, the ornamental variants of the common carp, are a striking example for color variability that was selected by man during a very short period on an evolutionary timescale. Among several pigmentation genes, genetic variation in Melanocrtin receptor 1 was repeatedly associated with dark pigmentation phenotypes in numerous animals. In this study, we cloned Melanocrtin receptor 1 from the common carp. We found that alleles of the gene were not associated with the development of black color in Koi. However, the mRNA expression levels of the gene were higher during dark pigmentation development in larvae and in dark pigmented tissues of adult fish, suggesting that variation in the regulation of the gene is associated with black color in Koi. These regulatory differences are reflected in both the timing of the dark-pigmentation development and the different mode of inheritance of the two black patterns associated with them. Identifying the genetic basis of color and color patterns in Koi will promote the production of this valuable ornamental fish. Furthermore, given the rich variety of colors and patterns, Koi serves as a good model to unravel pigmentation genes and their phenotypic effects and by that to improve our understanding of the genetic basis of colors also in natural populations. PMID:23355846

Study of magnetism in Ni-Cr hardface alloy deposit on 316LN stainless steel using magnetic force microscopy

NASA Astrophysics Data System (ADS)

Kishore, G. V. K.; Kumar, Anish; Chakraborty, Gopa; Albert, S. K.; Rao, B. Purna Chandra; Bhaduri, A. K.; Jayakumar, T.

2015-07-01

Nickel base Ni-Cr alloy variants are extensively used for hardfacing of austenitic stainless steel components in sodium cooled fast reactors (SFRs) to avoid self-welding and galling. Considerable difference in the compositions and melting points of the substrate and the Ni-Cr alloy results in significant dilution of the hardface deposit from the substrate. Even though, both the deposit and the substrate are non-magnetic, the diluted region exhibits ferromagnetic behavior. The present paper reports a systematic study carried out on the variations in microstructures and magnetic behavior of American Welding Society (AWS) Ni Cr-C deposited layers on 316 LN austenitic stainless steels, using atomic force microscopy (AFM) and magnetic force microscopy (MFM). The phase variations of the oscillations of a Co-Cr alloy coated magnetic field sensitive cantilever is used to quantitatively study the magnetic strength of the evolved microstructure in the diluted region as a function of the distance from the deposit/substrate interface, with the spatial resolution of about 100 nm. The acquired AFM/MFM images and the magnetic property profiles have been correlated with the variations in the chemical compositions in the diluted layers obtained by the energy dispersive spectroscopy (EDS). The study indicates that both the volume fraction of the ferromagnetic phase and its ferromagnetic strength decrease with increasing distance from the deposit/substrate interface. A distinct difference is observed in the ferromagnetic strength in the first few layers and the ferromagnetism is observed only near to the precipitates in the fifth layer. The study provides a better insight of the evolution of ferromagnetism in the diluted layers of Ni-Cr alloy deposits on stainless steel.

Genotype-by-environment interactions leads to variable selection on life-history strategy in Common Evening Primrose (Oenothera biennis).

PubMed

Johnson, M T J

2007-01-01

Monocarpic plant species, where reproduction is fatal, frequently exhibit variation in the length of their prereproductive period prior to flowering. If this life-history variation in flowering strategy has a genetic basis, genotype-by-environment interactions (G x E) may maintain phenotypic diversity in flowering strategy. The native monocarpic plant Common Evening Primrose (Oenothera biennis L., Onagraceae) exhibits phenotypic variation for annual vs. biennial flowering strategies. I tested whether there was a genetic basis to variation in flowering strategy in O. biennis, and whether environmental variation causes G x E that imposes variable selection on flowering strategy. In a field experiment, I randomized more than 900 plants from 14 clonal families (genotypes) into five distinct habitats that represented a natural productivity gradient. G x E strongly affected the lifetime fruit production of O. biennis, with the rank-order in relative fitness of genotypes changing substantially between habitats. I detected genetic variation in annual vs. biennial strategies in most habitats, as well as a G x E effect on flowering strategy. This variation in flowering strategy was correlated with genetic variation in relative fitness, and phenotypic and genotypic selection analyses revealed that environmental variation resulted in variable directional selection on annual vs. biennial strategies. Specifically, a biennial strategy was favoured in moderately productive environments, whereas an annual strategy was favoured in low-productivity environments. These results highlight the importance of variable selection for the maintenance of genetic variation in the life-history strategy of a monocarpic plant.

Temperature and electrical memory of polymer fibers

NASA Astrophysics Data System (ADS)

Yuan, Jinkai; Zakri, Cécile; Grillard, Fabienne; Neri, Wilfrid; Poulin, Philippe

2014-05-01

We report in this work studies of the shape memory behavior of polymer fibers loaded with carbon nanotubes or graphene flakes. These materials exhibit enhanced shape memory properties with the generation of a giant stress upon shape recovery. In addition, they exhibit a surprising temperature memory with a peak of generated stress at a temperature nearly equal to the temperature of programming. This temperature memory is ascribed to the presence of dynamical heterogeneities and to the intrinsic broadness of the glass transition. We present recent experiments related to observables other than mechanical properties. In particular nanocomposite fibers exhibit variations of electrical conductivity with an accurate memory. Indeed, the rate of conductivity variations during temperature changes reaches a well defined maximum at a temperature equal to the temperature of programming. Such materials are promising for future actuators that couple dimensional changes with sensing electronic functionalities.

Endodontic and Clinical Considerations in the Management of Variable Anatomy in Mandibular Premolars: A Literature Review

PubMed Central

Hammo, Mohammad

2014-01-01

Mandibular premolars are known to have numerous anatomic variations of their roots and root canals, which are a challenge to treat endodontically. The paper reviews literature to detail the various clinically relevant anatomic considerations with detailed techniques and methods to successfully manage these anomalies. An emphasis and detailed description of every step of treatment including preoperative diagnosis, intraoperative identification and management, and surgical endodontic considerations for the successful management of these complex cases have been included. PMID:24895584

Assessing the Relationship Between Sexual Concordance, Sexual Attractions, and Sexual Identity in Women.

PubMed

Suschinsky, Kelly D; Dawson, Samantha J; Chivers, Meredith L

2017-01-01

On average, there is a gender difference in sexual concordance, with men exhibiting greater agreement between genital and self-reported sexual arousal, relative to women. Much less is known about the substantial variation in women's sexual concordance; women's genital and self-reported sexual responses may correlate strongly and positively, not at all, or even strongly negatively. The within-gender variation in sexual concordance suggests that individual differences may be related to sexual concordance. We examined whether sexual concordance varies as a function of sexual orientation (based on self-reported sexual attractions and sexual identity labels) in a sample (N = 76) that included exclusively androphilic, predominantly androphilic, ambiphilic, and predominantly/exclusively gynephilic women. Participants viewed sexual and nonsexual stimuli that varied by actor gender while their vaginal vasocongestion and subjective sexual responses were measured. Women's sexual concordance varied as a function of their sexual attractions; women with any degree of gynephilia exhibited higher sexual concordance than exclusively androphilic women across a variety of sexual concordance measures, and these effects were demonstrated using correlation and multi-level modeling analyses. Only sexual concordance based on overall feelings of arousal varied by sexual identity, with heterosexual women exhibiting the lowest sexual concordance. Stimulus gender significantly influenced sexual concordance for most groups of women: Ambiphilic and predominantly/exclusively gynephilic women exhibited greater sexual concordance to female stimuli and exclusively androphilic women exhibited greater sexual concordance to male stimuli. These findings suggest that sexual orientation (particularly one's degree of gynephilia) may explain some of the within-gender variation seen in women's sexual concordance.

Identification of structural variation in mouse genomes.

PubMed

Keane, Thomas M; Wong, Kim; Adams, David J; Flint, Jonathan; Reymond, Alexandre; Yalcin, Binnaz

2014-01-01

Structural variation is variation in structure of DNA regions affecting DNA sequence length and/or orientation. It generally includes deletions, insertions, copy-number gains, inversions, and transposable elements. Traditionally, the identification of structural variation in genomes has been challenging. However, with the recent advances in high-throughput DNA sequencing and paired-end mapping (PEM) methods, the ability to identify structural variation and their respective association to human diseases has improved considerably. In this review, we describe our current knowledge of structural variation in the mouse, one of the prime model systems for studying human diseases and mammalian biology. We further present the evolutionary implications of structural variation on transposable elements. We conclude with future directions on the study of structural variation in mouse genomes that will increase our understanding of molecular architecture and functional consequences of structural variation.

Bold colors in a cryptic lineage: do Eastern Indigo Snakes exhibit color dimorphism?

PubMed

Deitloff, Jennifer; Johnson, Valerie M; Guyer, Craig

2013-01-01

Many species exhibit variation in the color of their scales, feathers, or fur. Various forms of natural selection, such as mimicry, crypsis, and species recognition, as well as sexual selection, can influence the evolution of color. Eastern Indigo Snakes (Drymarchon couperi), a federally threatened species, have coloration on the sides of the head and the chin that can vary from black to red or cream. Despite significant conservations efforts for this species, little is known about its biology in the field. Past researchers have proposed that the color variation on the head and chin is associated with the sex of the individual. Alternatively, color might vary among individuals because it is controlled by genes that are under natural selection or neutral evolution. We tested these alternative hypotheses by examining whether coloration of the sublabial, submaxillary, and ventral scales of this species differed by sex or among clutches. We used color spectrometry to characterize important aspects of color in two ways: by examining overall color differences across the entire color spectrum and by comparing differences within the ultraviolet, yellow, and red colorbands. We found that Eastern Indigo Snakes do not exhibit sexual dichromatism, but their coloration does vary among clutches; therefore, the pattern of sexual selection leading to sexual dichromatism observed in many squamates does not appear to play a role in the evolution and maintenance of color variation in Eastern Indigo Snakes. We suggest that future studies should focus on determining whether color variation in these snakes is determined by maternal effects or genetic components and if color is influenced by natural selection or neutral evolutionary processes. Studying species that exhibit bright colors within lineages that are not known for such coloration will contribute greatly to our understanding of the evolutionary and ecological factors that drive these differences.

Inter- and intraspecific variation in leaf economic traits in wheat and maize

PubMed Central

Hale, Christine E; Cerabolini, Bruno E L; Cornelissen, Johannes H C; Craine, Joseph; Gough, William A; Kattge, Jens; Tirona, Cairan K F

2018-01-01

Abstract Leaf Economics Spectrum (LES) trait variation underpins multiple agroecological processes and many prominent crop yield models. While there are numerous independent studies assessing trait variation in crops, to date there have been no comprehensive assessments of intraspecific trait variation (ITV) in LES traits for wheat and maize: the world’s most widespread crops. Using trait databases and peer-reviewed literature, we compiled over 700 records of specific leaf area (SLA), maximum photosynthetic rates (Amax) and leaf nitrogen (N) concentrations, for wheat and maize. We evaluated intraspecific LES trait variation, and intraspecific trait–environment relationships. While wheat and maize occupy the upper 90th percentile of LES trait values observed across a global species pool, ITV ranged widely across the LES in wheat and maize. Fertilization treatments had strong impacts on leaf N, while plant developmental stage (here standardized as the number of days since planting) had strong impacts on Amax; days since planting, N fertilization and irrigation all influenced SLA. When controlling for these factors, intraspecific responses to temperature and precipitation explained 39.4 and 43.7 % of the variation in Amax and SLA, respectively, but only 5.4 % of the variation in leaf N. Despite a long history of domestication in these species, ITV in wheat and maize among and within cultivars remains large. Intraspecific trait variation is a critical consideration to refine regional to global models of agroecosystem structure, function and food security. Considerable opportunities and benefits exist for consolidating a crop trait database for a wider range of domesticated plant species. PMID:29484152

Inter- and intraspecific variation in leaf economic traits in wheat and maize.

PubMed

Martin, Adam R; Hale, Christine E; Cerabolini, Bruno E L; Cornelissen, Johannes H C; Craine, Joseph; Gough, William A; Kattge, Jens; Tirona, Cairan K F

2018-02-01

Leaf Economics Spectrum (LES) trait variation underpins multiple agroecological processes and many prominent crop yield models. While there are numerous independent studies assessing trait variation in crops, to date there have been no comprehensive assessments of intraspecific trait variation (ITV) in LES traits for wheat and maize: the world's most widespread crops. Using trait databases and peer-reviewed literature, we compiled over 700 records of specific leaf area (SLA), maximum photosynthetic rates ( A max ) and leaf nitrogen (N) concentrations, for wheat and maize. We evaluated intraspecific LES trait variation, and intraspecific trait-environment relationships. While wheat and maize occupy the upper 90th percentile of LES trait values observed across a global species pool, ITV ranged widely across the LES in wheat and maize. Fertilization treatments had strong impacts on leaf N, while plant developmental stage (here standardized as the number of days since planting) had strong impacts on A max ; days since planting, N fertilization and irrigation all influenced SLA. When controlling for these factors, intraspecific responses to temperature and precipitation explained 39.4 and 43.7 % of the variation in A max and SLA, respectively, but only 5.4 % of the variation in leaf N. Despite a long history of domestication in these species, ITV in wheat and maize among and within cultivars remains large. Intraspecific trait variation is a critical consideration to refine regional to global models of agroecosystem structure, function and food security. Considerable opportunities and benefits exist for consolidating a crop trait database for a wider range of domesticated plant species.

Elevated temperature is more effective than elevated [CO2 ] in exposing genotypic variation in Telopea speciosissima growth plasticity: implications for woody plant populations under climate change.

PubMed

Huang, Guomin; Rymer, Paul D; Duan, Honglang; Smith, Renee A; Tissue, David T

2015-10-01

Intraspecific variation in phenotypic plasticity is a critical determinant of plant species capacity to cope with climate change. A long-standing hypothesis states that greater levels of environmental variability will select for genotypes with greater phenotypic plasticity. However, few studies have examined how genotypes of woody species originating from contrasting environments respond to multiple climate change factors. Here, we investigated the main and interactive effects of elevated [CO2 ] (CE ) and elevated temperature (TE ) on growth and physiology of Coastal (warmer, less variable temperature environment) and Upland (cooler, more variable temperature environment) genotypes of an Australian woody species Telopea speciosissima. Both genotypes were positively responsive to CE (35% and 29% increase in whole-plant dry mass and leaf area, respectively), but only the Coastal genotype exhibited positive growth responses to TE . We found that the Coastal genotype exhibited greater growth response to TE (47% and 85% increase in whole-plant dry mass and leaf area, respectively) when compared with the Upland genotype (no change in dry mass or leaf area). No intraspecific variation in physiological plasticity was detected under CE or TE , and the interactive effects of CE and TE on intraspecific variation in phenotypic plasticity were also largely absent. Overall, TE was a more effective climate factor than CE in exposing genotypic variation in our woody species. Our results contradict the paradigm that genotypes from more variable climates will exhibit greater phenotypic plasticity in future climate regimes. © 2015 John Wiley & Sons Ltd.

Estimating nonrigid motion from inconsistent intensity with robust shape features

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

Liu, Wenyang; Ruan, Dan, E-mail: druan@mednet.ucla.edu; Department of Radiation Oncology, University of California, Los Angeles, California 90095

2013-12-15

Purpose: To develop a nonrigid motion estimation method that is robust to heterogeneous intensity inconsistencies amongst the image pairs or image sequence. Methods: Intensity and contrast variations, as in dynamic contrast enhanced magnetic resonance imaging, present a considerable challenge to registration methods based on general discrepancy metrics. In this study, the authors propose and validate a novel method that is robust to such variations by utilizing shape features. The geometry of interest (GOI) is represented with a flexible zero level set, segmented via well-behaved regularized optimization. The optimization energy drives the zero level set to high image gradient regions, andmore » regularizes it with area and curvature priors. The resulting shape exhibits high consistency even in the presence of intensity or contrast variations. Subsequently, a multiscale nonrigid registration is performed to seek a regular deformation field that minimizes shape discrepancy in the vicinity of GOIs. Results: To establish the working principle, realistic 2D and 3D images were subject to simulated nonrigid motion and synthetic intensity variations, so as to enable quantitative evaluation of registration performance. The proposed method was benchmarked against three alternative registration approaches, specifically, optical flow, B-spline based mutual information, and multimodality demons. When intensity consistency was satisfied, all methods had comparable registration accuracy for the GOIs. When intensities among registration pairs were inconsistent, however, the proposed method yielded pronounced improvement in registration accuracy, with an approximate fivefold reduction in mean absolute error (MAE = 2.25 mm, SD = 0.98 mm), compared to optical flow (MAE = 9.23 mm, SD = 5.36 mm), B-spline based mutual information (MAE = 9.57 mm, SD = 8.74 mm) and mutimodality demons (MAE = 10.07 mm, SD = 4.03 mm). Applying the proposed method on a real MR image sequence also provided qualitatively appealing results, demonstrating good feasibility and applicability of the proposed method. Conclusions: The authors have developed a novel method to estimate the nonrigid motion of GOIs in the presence of spatial intensity and contrast variations, taking advantage of robust shape features. Quantitative analysis and qualitative evaluation demonstrated good promise of the proposed method. Further clinical assessment and validation is being performed.« less

Estimating nonrigid motion from inconsistent intensity with robust shape features.

PubMed

Liu, Wenyang; Ruan, Dan

2013-12-01

To develop a nonrigid motion estimation method that is robust to heterogeneous intensity inconsistencies amongst the image pairs or image sequence. Intensity and contrast variations, as in dynamic contrast enhanced magnetic resonance imaging, present a considerable challenge to registration methods based on general discrepancy metrics. In this study, the authors propose and validate a novel method that is robust to such variations by utilizing shape features. The geometry of interest (GOI) is represented with a flexible zero level set, segmented via well-behaved regularized optimization. The optimization energy drives the zero level set to high image gradient regions, and regularizes it with area and curvature priors. The resulting shape exhibits high consistency even in the presence of intensity or contrast variations. Subsequently, a multiscale nonrigid registration is performed to seek a regular deformation field that minimizes shape discrepancy in the vicinity of GOIs. To establish the working principle, realistic 2D and 3D images were subject to simulated nonrigid motion and synthetic intensity variations, so as to enable quantitative evaluation of registration performance. The proposed method was benchmarked against three alternative registration approaches, specifically, optical flow, B-spline based mutual information, and multimodality demons. When intensity consistency was satisfied, all methods had comparable registration accuracy for the GOIs. When intensities among registration pairs were inconsistent, however, the proposed method yielded pronounced improvement in registration accuracy, with an approximate fivefold reduction in mean absolute error (MAE = 2.25 mm, SD = 0.98 mm), compared to optical flow (MAE = 9.23 mm, SD = 5.36 mm), B-spline based mutual information (MAE = 9.57 mm, SD = 8.74 mm) and mutimodality demons (MAE = 10.07 mm, SD = 4.03 mm). Applying the proposed method on a real MR image sequence also provided qualitatively appealing results, demonstrating good feasibility and applicability of the proposed method. The authors have developed a novel method to estimate the nonrigid motion of GOIs in the presence of spatial intensity and contrast variations, taking advantage of robust shape features. Quantitative analysis and qualitative evaluation demonstrated good promise of the proposed method. Further clinical assessment and validation is being performed.

PHASE RELATIONSHIPS OF SOLAR HEMISPHERIC TOROIDAL AND POLOIDAL CYCLES

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

Muraközy, J., E-mail: murakozy.judit@csfk.mta.hu

2016-08-01

The solar northern and southern hemispheres exhibit differences in their intensities and time profiles of the activity cycles. The time variation of these properties was studied in a previous article covering the data from Cycles 12–23. The hemispheric phase lags exhibited a characteristic variation: the leading role was exchanged between hemispheres every four cycles. The present work extends the investigation of this variation using the data of Staudacher and Schwabe in Cycles 1–4 and 7–10 as well as Spörer’s data in Cycle 11. The previously observed variation cannot be clearly recognized using the data of Staudacher, Schwabe, and Spörer. However,more » it is more interesting that the phase lags of the reversals of the magnetic fields at the poles follow the same variations as those of the hemispheric cycles in Cycles 12–23, i.e., one of the hemispheres leads in four cyles and the leading role jumps to the opposite hemisphere in the next four cycles. This means that this variation is a long-term property of the entire solar dynamo mechanism, for both the toroidal and poloidal fields, which hints at an unidentified component of the process responsible for the long-term memory.« less

Genetic variation in heat-stress tolerance among South American Drosophila populations.

PubMed

Fallis, Lindsey C; Fanara, Juan Jose; Morgan, Theodore J

2011-10-01

Spatial or temporal differences in environmental variables, such as temperature, are ubiquitous in nature and impose stress on organisms. This is especially true for organisms that are isothermal with the environment, such as insects. Understanding the means by which insects respond to temperature and how they will react to novel changes in environmental temperature is important for understanding the adaptive capacity of populations and to predict future trajectories of evolutionary change. The organismal response to heat has been identified as an important environmental variable for insects that can dramatically influence life history characters and geographic range. In the current study we surveyed the amount of variation in heat tolerance among Drosophila melanogaster populations collected at diverse sites along a latitudinal gradient in Argentina (24°-38°S). This is the first study to quantify heat tolerance in South American populations and our work demonstrates that most of the populations surveyed have abundant within-population phenotypic variation, while still exhibiting significant variation among populations. The one exception was the most heat tolerant population that comes from a climate exhibiting the warmest annual mean temperature. All together our results suggest there is abundant genetic variation for heat-tolerance phenotypes within and among natural populations of Drosophila and this variation has likely been shaped by environmental temperature.

Positive Relationship between Abdominal Coloration and Dermal Melanin Density in Phrynosomatid Lizards

Treesearch

Vanessa S. Quinn; Diana K. Hews

2003-01-01

Phrynosomatid lizards show considerable variation among species in the occurrence of a secondary sexual trait, blue abdominal coloration. The production of blue skin may be controlled by at least two cellular components, melanin in melanophores, and guanine in iridophores. To examine the hypothesis that a mechanism producing variation in abdominal coloration is...

The Adoption of Variation Theory in the Classroom: Effect on Students' Algebraic Achievement and Motivation to Learn

ERIC Educational Resources Information Center

Ting, Jing Jing; Tarmizi, Rohani Tarmizi; Bakar, Kamariah Abu; Aralas, Dalia

2017-01-01

Introduction: Analysis of lessons held in East Asia regions that perform well in Trends in International Mathematics and Science Studies such as; South Korea, Hong Kong and Japan, demonstrated teachers in mathematics classroom enacted features of the content systematically with consideration of variation within students' capabilities. Recent…

Geographical variation in camper expenditures

Treesearch

Wilbur F. LaPage; Edward G. Fisher

1971-01-01

Daily expenditures by families camping in New Hampshire State parks in 1967 averaged $11.81. Considerable variation was found between the northern, central, and southern regions of the State in both the average amount of money spent and the way in which the money was spent. Daily expenditures in the north were higher, but average visit lengths were shorter, resulting...

A Review of the Hypoglycemic Effects of Five Commonly Used Herbal Food Supplements

PubMed Central

Deng, Ruitang

2013-01-01

Hyperglycemia is a pathological condition associated with prediabetes and diabetes. The incidence of prediabetes and diabetes is increasing and imposes great burden on healthcare worldwide. Patients with prediabetes and diabetes have significantly increased risk for cardiovascular diseases and other complications. Currently, management of hyperglycemia includes pharmacological interventions, physical exercise, and change of life style and diet. Food supplements have increasingly become attractive alternatives to prevent or treat hyperglycemia, especially for subjects with mild hyperglycemia. This review summarized current patents and patent applications with relevant literature on five commonly used food supplements with claims of hypoglycemic effects, including emblica officinalis (gooseberry), fenugreek, green tea, momordica charantia (bitter melon) and cinnamon. The data from human clinical studies did not support a recommendation for all five supplements to manage hyperglycemia. Fenugreek and composite supplements containing emblica officinalis showed the most consistency in lowering fasting blood sugar (FBS) or glycated hemoglobin (HbA1c) levels in diabetic patients. The hypoglycemic effects of cinnamon and momordica charantia were demonstrated in most of the trials with some exceptions. However, green tea exhibited limited benefits in reducing FBS or HbA1c levels and should not be recommended for managing hyperglycemia. Certain limitations are noticed in a considerable number of clinical studies including small sample size, poor experimental design and considerable variations in participant population, preparation format, daily dose, and treatment duration. Future studies with more defined participants, standardized preparation and dose, and improved trial design and size are warranted. PMID:22329631

The effects of railway transportation on the enrichment of heavy metals in the artificial soil on railway cut slopes.

PubMed

Chen, Zhaoqiong; Wang, KeXiu; Ai, Ying Wei; Li, Wei; Gao, Hongying; Fang, Chen

2014-02-01

Heavy metal contamination in the artificial soils on the railway cut slopes may have great influence on the revegetation of the cut slopes. The purpose of this study was to assess the variation of heavy metal contamination levels with railway operation time and analyze their possible resources. A total of 100 soil samples from four cut slopes, which were affected by railway transportation for different years, were analyzed for metal pollution (Cd, Pb, Cr, Cu, Zn, Fe). The concentrations of Cd, Pb showed increasing trend with increasing operation time of railways, while such trend was not found in Cr, Cu, Zn, Fe. According to the soil quality standard of China, Cd was considered to have considerable contamination, while Pb has less, but Cr, Cu, Zn, Fe have none. Moreover, cadmium exhibited remarkably higher levels rather than those reported in other studies. Enrichment factors and ecological index showed that Cd and Pb showed a moderate enrichment and a considerable ecological risk in most of the soil samples. The results of descriptive statistic, principal component analysis, cluster analysis and correlation analysis were totally consistent with each other. Their results revealed that Cr, Cu, Zn and Fe had common origins, and they may come from natural resources. While Cd and Pb were significantly influenced by railway transportation, leaked cargos, fuel combustion, the use of lubricate oils and sleeper impregnation oils during railway transportation may be their main resources.

The radiated electromagnetic field from collimated gamma rays and electron beams in air

NASA Astrophysics Data System (ADS)

Tumolillo, T. A.; Wondra, J. P.; Hobbs, W. E.; Smith, K.

1980-12-01

Nuclear weapons effects computer codes are used to study the electromagnetic field produced by gamma rays or by highly relativistic electron beams moving through the air. Consideration is given to large-area electron and gamma beams, small-area electron beams, variation of total beam current, variation of pressure in the beam channel, variation of the beam rise time, variation of beam radius, far-field radiated signals, and induced current on a system from a charged-particle beam. The work has application to system EMP coupling from nuclear weapons or charged-particle-beam weapons.

Two unusual anatomic variations create a diagnostic dilemma in distal ulnar nerve compression.

PubMed

Kiehn, Mark W; Derrick, Allison J; Iskandar, Bermans J

2008-09-01

Diagnosis of peripheral neuropathies is based upon patterns of functional deficits and electrodiagnostic testing. However, anatomic variations can lead to confounding patterns of physical and electrodiagnostic findings. Authors present a case of ulnar nerve compression due to a rare combination of anatomic variations, aberrant branching pattern, and FCU insertion at the wrist, which posed a diagnostic and therapeutic dilemma. The literature related to isolated distal ulnar motor neuropathy and anatomic variations of the ulnar nerve and adjacent structures is also reviewed. This case demonstrates how anatomic variations can complicate the interpretation of clinical and electrodiagnostic findings and underscores the importance of thorough exploration of the nerve in consideration for possible variations. (c) 2008 Wiley-Liss, Inc.

Application of variational and Galerkin equations to linear and nonlinear finite element analysis

NASA Technical Reports Server (NTRS)

Yu, Y.-Y.

1974-01-01

The paper discusses the application of the variational equation to nonlinear finite element analysis. The problem of beam vibration with large deflection is considered. The variational equation is shown to be flexible in both the solution of a general problem and in the finite element formulation. Difficulties are shown to arise when Galerkin's equations are used in the consideration of the finite element formulation of two-dimensional linear elasticity and of the linear classical beam.

Relative Radiation Density and Temperature Distribution of Rocket Flames

DTIC Science & Technology

1951-07-10

traversed along the axis of the flame image to determine the flame length and the position of the Mach nodes. Other traverses were made across the...variation is due to different stages of flame growth. Other variations especially those of 2 6• flame length , can be accounted for by dif- U L L ference...The temperature gradient is considerably less at the tip of the flame and by similar reasoning would give greater variation in flame length . The problem

Magnetic resonance cholangiographic evaluation of intrahepatic and extrahepatic bile duct variations

PubMed Central

Sureka, Binit; Bansal, Kalpana; Patidar, Yashwant; Arora, Ankur

2016-01-01

Biliary anatomy and its common and uncommon variations are of considerable clinical significance when performing living donor transplantation, radiological interventions in hepatobiliary system, laparoscopic cholecystectomy, and liver resection (hepatectomy, segmentectomy). Because of increasing trend found in the number of liver transplant surgeries being performed, magnetic resonance cholangiopancreatography (MRCP) has become the modality of choice for noninvasive evaluation of abnormalities of the biliary tract. The purpose of this study is to describe the anatomic variations of the intrahepatic and extrahepatic biliary tree. PMID:27081220

SU-F-T-394: Impact of PTV Margins With Taking Into Account Shape Variation On IMRT Plans For Prostate Cancer

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

Hirose, T; Arimura, H; Oga, S

2016-06-15

Purpose: The purpose of this study was to investigate the impact of planning target volume (PTV) margins with taking into consideration clinical target volume (CTV) shape variations on treatment plans of intensity modulated radiation therapy (IMRT) for prostate cancer. Methods: The systematic errors and the random errors for patient setup errors in right-left (RL), anterior-posterior (AP), and superior-inferior (SI) directions were obtained from data of 20 patients, and those for CTV shape variations were calculated from 10 patients, who were weekly scanned using cone beam computed tomography (CBCT). The setup error was defined as the difference in prostate centers betweenmore » planning CT and CBCT images after bone-based registrations. CTV shape variations of high, intermediate and low risk CTVs were calculated for each patient from variances of interfractional shape variations on each vertex of three-dimensional CTV point distributions, which were manually obtained from CTV contours on the CBCT images. PTV margins were calculated using the setup errors with and without CTV shape variations for each risk CTV. Six treatment plans were retrospectively made by using the PTV margins with and without CTV shape variations for the three risk CTVs of 5 test patients. Furthermore, the treatment plans were applied to CBCT images for investigating the impact of shape variations on PTV margins. Results: The percentages of population to cover with the PTV, which satisfies the CTV D98 of 95%, with and without the shape variations were 89.7% and 74.4% for high risk, 89.7% and 76.9% for intermediate risk, 84.6% and 76.9% for low risk, respectively. Conclusion: PTV margins taking into account CTV shape variation provide significant improvement of applicable percentage of population (P < 0.05). This study suggested that CTV shape variation should be taken consideration into determination of the PTV margins.« less

Consideration of Materials for Aircraft Brakes

NASA Technical Reports Server (NTRS)

Peterson, M. B.; Ho, T.

1972-01-01

An exploratory investigation was conducted concerning materials and their properties for use in aircraft brakes. Primary consideration was given to the heat dissipation and the frictional behavior of materials. Used brake pads and rotors were analyzed as part of the investigation. A simple analysis was conducted in order to determine the most significant factors which affect surface temperatures. It was found that where size and weight restrictions are necessary, the specific heat of the material, and maintaining uniform contact area are the most important factors. A criterion was suggested for optimum sizing of the brake disks. Bench friction tests were run with brake materials. It was found that there is considerable friction variation due to the formation and removal of surface oxide films. Other causes of friction variations are surface softening and melting. The friction behavior at high temperature was found to be more characteristic of the steel surface rather than the copper brake material. It is concluded that improved brake materials are feasible.

The Sun: Source of the Earth's Energy

NASA Technical Reports Server (NTRS)

Thompson, Barbara J.; Fisher, Richard R. (Technical Monitor)

2001-01-01

The Sun is the primary source of the Earth's energy. However, due to the complexity in the way the energy affects Earth, the various solar sources of the energy, and the variation exhibited by the Sun it is difficult to understand and predict the Earth's response to solar drivers. In addition to visible light the radiant energy of the Sun can exhibit variation in nearly all wavelengths, which can vary over nearly all timescales. Depending on the wavelength of the incident radiation the light can deposit energy in a wide variety or locations and drive processes from below Earth's surface to interplanetary space. Other sources of energy impacting Earth include energetic particles, magnetic fields, and mass and flow variations in the solar wind. Many of these variable energetic processes cannot be coupled and recent results continue to demonstrate that the complex dynamics of the Sun can have a great range of measurable impacts on Earth.

Stochastic and compensatory effects limit persistence of variation in body mass of young caribou

USGS Publications Warehouse

Dale, Bruce W.; Adams, Layne G.; Collins, William B.; Joly, Kyle; Valkenburg, Patrick; Tobey, Robert

2008-01-01

Nutritional restriction during growth can have short- and long-term effects on fitness; however, animals inhabiting uncertain environments may exhibit adaptations to cope with variation in food availability. We examined changes in body mass in free-ranging female caribou (Rangifer tarandus) by measuring mass at birth and at 4, 11, and 16 months of age to evaluate the relative importance of seasonal nutrition to growth, the persistence of cohort-specific variation in body mass through time, and compensatory growth of individuals. Relative mean body mass of cohorts did not persist through time. Compensatory growth of smaller individuals was not observed in summer; however, small calves exhibited more positive change in body mass than did large calves. Compensation occurred during periods of nutritional restriction (winter) rather than during periods of rapid growth (summer) thus differing from the conventional view of compensatory growth.

Huge domain-wall speed variation with respect to ferromagnetic layer thickness in ferromagnetic Pt/Co/TiO2/Pt films

NASA Astrophysics Data System (ADS)

Kim, Dae-Yun; Park, Min-Ho; Park, Yong-Keun; Yu, Ji-Sung; Kim, Joo-Sung; Kim, Duck-Ho; Min, Byoung-Chul; Choe, Sug-Bong

2018-02-01

In this study, we investigate the influence of the ferromagnetic layer thickness on the magnetization process. A series of ultrathin Pt/Co/TiO2/Pt films exhibits domain-wall (DW) speed variation of over 100,000 times even under the same magnetic field, depending on the ferromagnetic layer thickness. From the creep-scaling analysis, such significant variation is found to be mainly attributable to the thickness-dependence of the creep-scaling constant in accordance with the creep-scaling theory of the linear proportionality between the creep-scaling constant and the ferromagnetic layer thickness. Therefore, a thinner film shows a faster DW speed. The DW roughness also exhibits sensitive dependence on the ferromagnetic layer thickness: a thinner film shows smoother DW. The present observation provided a guide for an optimal design rule of the ferromagnetic layer thickness for better performance of DW-based devices.

Immunological characterization of the gluten fractions and their hydrolysates from wheat, rye and barley.

PubMed

Rallabhandi, Prasad; Sharma, Girdhari M; Pereira, Marion; Williams, Kristina M

2015-02-18

Gluten proteins in wheat, rye and barley cause celiac disease, an autoimmune disorder of the small intestine, which affects approximately 1% of the world population. Gluten is comprised of prolamin and glutelin. Since avoidance of dietary gluten is the only option for celiac patients, a sensitive gluten detection and quantitation method is warranted. Most regulatory agencies have set a threshold of 20 ppm gluten in foods labeled gluten-free, based on the currently available ELISA methods. However, these methods may exhibit differences in gluten quantitation from different gluten-containing grains. In this study, prolamin and glutelin fractions were isolated from wheat, rye, barley, oats and corn. Intact and pepsin-trypsin (PT)-digested prolamin and glutelin fractions were used to assess their immunoreactivity and gluten recovery by three sandwich and two competitive ELISA kits. The Western blots revealed varied affinity of ELISA antibodies to gluten-containing grain proteins and no reactivity to oat and corn proteins. ELISA results showed considerable variation in gluten recoveries from both intact and PT-digested gluten fractions among different kits. Prolamin fractions showed higher gluten recovery compared to their respective glutelin fractions. Among prolamins, barley exhibited higher recovery compared to wheat and rye with most of the ELISA kits used. Hydrolysis resulted in reduced gluten recovery of most gluten fractions. These results suggest that the suitability of ELISA for accurate gluten quantitation is dependent upon various factors, such as grain source, antibody specificity, gluten proteins and the level of their hydrolysis in foods.

Earth as art three

USGS Publications Warehouse

,

2010-01-01

For most of us, deserts, mountains, river valleys, coastlines even dry lakebeds are relatively familiar features of the Earth's terrestrial environment. For earth scientists, they are the focus of considerable scientific research. Viewed from a unique and unconventional perspective, Earth's geographic attributes can also be a surprising source of awe-inspiring art. That unique perspective is space. The artists for the Earth as Art Three exhibit are the Landsat 5 and Landsat 7 satellites, which orbit approximately 705 kilometers (438 miles) above the Earth's surface. While studying the images these satellites beam down daily, researchers are often struck by the sheer beauty of the scenes. Such images inspire the imagination and go beyond scientific value to remind us how stunning, intricate, and simply amazing our planet's features can be. Instead of paint, the medium for these works of art is light. But Landsat satellite sensors don't see light as human eyes do; instead, they see radiant energy reflected from Earth's surface in certain wavelengths, or bands, of red, green, blue, and infrared light. When these different bands are combined into a single image, remarkable patterns, colors, and shapes emerge. The Earth as Art Three exhibit provides fresh and inspiring glimpses of different parts of our planet's complex surface. The images in this collection were chosen solely based on their aesthetic appeal. Many of the images have been manipulated to enhance color variations or details. They are not intended for scientific interpretation only for your viewing pleasure. Enjoy!

A harmonic analysis approach to joint inversion of P-receiver functions and wave dispersion data in high dense seismic profiles

NASA Astrophysics Data System (ADS)

Molina-Aguilera, A.; Mancilla, F. D. L.; Julià, J.; Morales, J.

2017-12-01

Joint inversion techniques of P-receiver functions and wave dispersion data implicitly assume an isotropic radial stratified earth. The conventional approach invert stacked radial component receiver functions from different back-azimuths to obtain a laterally homogeneous single-velocity model. However, in the presence of strong lateral heterogeneities as anisotropic layers and/or dipping interfaces, receiver functions are considerably perturbed and both the radial and transverse components exhibit back azimuthal dependences. Harmonic analysis methods exploit these azimuthal periodicities to separate the effects due to the isotropic flat-layered structure from those effects caused by lateral heterogeneities. We implement a harmonic analysis method based on radial and transverse receiver functions components and carry out a synthetic study to illuminate the capabilities of the method in isolating the isotropic flat-layered part of receiver functions and constrain the geometry and strength of lateral heterogeneities. The independent of the baz P receiver function are jointly inverted with phase and group dispersion curves using a linearized inversion procedure. We apply this approach to high dense seismic profiles ( 2 km inter-station distance, see figure) located in the central Betics (western Mediterranean region), a region which has experienced complex geodynamic processes and exhibit strong variations in Moho topography. The technique presented here is robust and can be applied systematically to construct a 3-D model of the crust and uppermost mantle across large networks.

Biophysical properties of intrinsically disordered p130Cas substrate domain--implication in mechanosensing.

PubMed

Hotta, Kinya; Ranganathan, Soumya; Liu, Ruchuan; Wu, Fei; Machiyama, Hiroaki; Gao, Rong; Hirata, Hiroaki; Soni, Neelesh; Ohe, Takashi; Hogue, Christopher W V; Madhusudhan, M S; Sawada, Yasuhiro

2014-04-01

Mechanical stretch-induced tyrosine phosphorylation in the proline-rich 306-residue substrate domain (CasSD) of p130Cas (or BCAR1) has eluded an experimentally validated structural understanding. Cellular p130Cas tyrosine phosphorylation is shown to function in areas without internal actomyosin contractility, sensing force at the leading edge of cell migration. Circular dichroism shows CasSD is intrinsically disordered with dominant polyproline type II conformations. Strongly conserved in placental mammals, the proline-rich sequence exhibits a pseudo-repeat unit with variation hotspots 2-9 residues before substrate tyrosine residues. Atomic-force microscopy pulling experiments show CasSD requires minimal extension force and exhibits infrequent, random regions of weak stability. Proteolysis, light scattering and ultracentrifugation results show that a monomeric intrinsically disordered form persists for CasSD in solution with an expanded hydrodynamic radius. All-atom 3D conformer sampling with the TraDES package yields ensembles in agreement with experiment when coil-biased sampling is used, matching the experimental radius of gyration. Increasing β-sampling propensities increases the number of prolate conformers. Combining the results, we conclude that CasSD has no stable compact structure and is unlikely to efficiently autoinhibit phosphorylation. Taking into consideration the structural propensity of CasSD and the fact that it is known to bind to LIM domains, we propose a model of how CasSD and LIM domain family of transcription factor proteins may function together to regulate phosphorylation of CasSD and effect machanosensing.

Fast but fleeting: adaptive motor learning processes associated with aging and cognitive decline.

PubMed

Trewartha, Kevin M; Garcia, Angeles; Wolpert, Daniel M; Flanagan, J Randall

2014-10-01

Motor learning has been shown to depend on multiple interacting learning processes. For example, learning to adapt when moving grasped objects with novel dynamics involves a fast process that adapts and decays quickly-and that has been linked to explicit memory-and a slower process that adapts and decays more gradually. Each process is characterized by a learning rate that controls how strongly motor memory is updated based on experienced errors and a retention factor determining the movement-to-movement decay in motor memory. Here we examined whether fast and slow motor learning processes involved in learning novel dynamics differ between younger and older adults. In addition, we investigated how age-related decline in explicit memory performance influences learning and retention parameters. Although the groups adapted equally well, they did so with markedly different underlying processes. Whereas the groups had similar fast processes, they had different slow processes. Specifically, the older adults exhibited decreased retention in their slow process compared with younger adults. Within the older group, who exhibited considerable variation in explicit memory performance, we found that poor explicit memory was associated with reduced retention in the fast process, as well as the slow process. These findings suggest that explicit memory resources are a determining factor in impairments in the both the fast and slow processes for motor learning but that aging effects on the slow process are independent of explicit memory declines. Copyright © 2014 the authors 0270-6474/14/3413411-11$15.00/0.

Study of the generated genetic polymorphisms during the photocatalytic elimination of Klebsiella pneumoniae in water.

PubMed

Venieri, Danae; Fraggedaki, Antonia; Binas, Vassilios; Zachopoulos, Apostolos; Kiriakidis, George; Mantzavinos, Dionissios

2015-03-01

Klebsiella pneumoniae is considered to be an emerging pathogen persisting under extreme environmentally stressed conditions. The aim of the present study is the investigation of inactivation rates of this pathogen in water by means of heterogeneous photocatalytic treatment under solar irradiation and the induced genetic variance applying RAPD-PCR as a molecular typing tool. Novel Mn- and Co-doped TiO2 catalysts were assessed in terms of their disinfection efficiency. The reference strain of K. pneumoniae proved to be readily inactivated, since disinfection occurred rapidly (i.e. after only 10 min of treatment) and low levels of bacterial regrowth were recorded in the dark and under natural sunlight. Binary doped titania exhibited the best photocatalytic activity, verifying the synergistic effect induced by composite dopants. Applying RAPD analysis to viable cells after treatment we concluded that increasing the treatment time led to considerable alteration of RAPD profiles and the homology coefficient ranged almost between 35 and 60%. RAPD-PCR proved to be a useful typing molecular tool that under standardized conditions exhibits highly reproducible results. Genetic variation among isolates increased in relation to the period of treatment and prolonged irradiation in each case affected the overall alteration in band patterns. RAPD patterns were highly diverse between treated and untreated isolates when disinfection was performed with the Co-doped titania. The broad spectrum of genetic variance and generated polymorphisms has the potential to increase the already significant virulence of the species.

Overcoming the loss of blue sensitivity through opsin duplication in the largest animal group, beetles.

PubMed

Sharkey, Camilla R; Fujimoto, M Stanley; Lord, Nathan P; Shin, Seunggwan; McKenna, Duane D; Suvorov, Anton; Martin, Gavin J; Bybee, Seth M

2017-01-31

Opsin proteins are fundamental components of animal vision whose structure largely determines the sensitivity of visual pigments to different wavelengths of light. Surprisingly little is known about opsin evolution in beetles, even though they are the most species rich animal group on Earth and exhibit considerable variation in visual system sensitivities. We reveal the patterns of opsin evolution across 62 beetle species and relatives. Our results show that the major insect opsin class (SW) that typically confers sensitivity to "blue" wavelengths was lost ~300 million years ago, before the origin of modern beetles. We propose that UV and LW opsin gene duplications have restored the potential for trichromacy (three separate channels for colour vision) in beetles up to 12 times and more specifically, duplications within the UV opsin class have likely led to the restoration of "blue" sensitivity up to 10 times. This finding reveals unexpected plasticity within the insect visual system and highlights its remarkable ability to evolve and adapt to the available light and visual cues present in the environment.

The human gut microbiome, a taxonomic conundrum.

PubMed

Sankar, Senthil Alias; Lagier, Jean-Christophe; Pontarotti, Pierre; Raoult, Didier; Fournier, Pierre-Edouard

2015-06-01

From culture to metagenomics, within only 130 years, our knowledge of the human microbiome has considerably improved. With >1000 microbial species identified to date, the gastro-intestinal microbiota is the most complex of human biotas. It is composed of a majority of Bacteroidetes and Firmicutes and, although exhibiting great inter-individual variations according to age, geographic origin, disease or antibiotic uptake, it is stable over time. Metagenomic studies have suggested associations between specific gut microbiota compositions and a variety of diseases, including irritable bowel syndrome, Crohn's disease, colon cancer, type 2 diabetes and obesity. However, these data remain method-dependent, as no consensus strategy has been defined to decipher the complexity of the gut microbiota. High-throughput culture-independent techniques have highlighted the limitations of culture by showing the importance of uncultured species, whereas modern culture methods have demonstrated that metagenomics underestimates the microbial diversity by ignoring minor populations. In this review, we highlight the progress and challenges that pave the way to a complete understanding of the human gastrointestinal microbiota and its influence on human health. Copyright © 2015 Elsevier GmbH. All rights reserved.

Scrutinizing MHC-I binding peptides and their limits of variation.

PubMed

Koch, Christian P; Perna, Anna M; Pillong, Max; Todoroff, Nickolay K; Wrede, Paul; Folkers, Gerd; Hiss, Jan A; Schneider, Gisbert

2013-01-01

Designed peptides that bind to major histocompatibility protein I (MHC-I) allomorphs bear the promise of representing epitopes that stimulate a desired immune response. A rigorous bioinformatical exploration of sequence patterns hidden in peptides that bind to the mouse MHC-I allomorph H-2K(b) is presented. We exemplify and validate these motif findings by systematically dissecting the epitope SIINFEKL and analyzing the resulting fragments for their binding potential to H-2K(b) in a thermal denaturation assay. The results demonstrate that only fragments exclusively retaining the carboxy- or amino-terminus of the reference peptide exhibit significant binding potential, with the N-terminal pentapeptide SIINF as shortest ligand. This study demonstrates that sophisticated machine-learning algorithms excel at extracting fine-grained patterns from peptide sequence data and predicting MHC-I binding peptides, thereby considerably extending existing linear prediction models and providing a fresh view on the computer-based molecular design of future synthetic vaccines. The server for prediction is available at http://modlab-cadd.ethz.ch (SLiDER tool, MHC-I version 2012).

Iceberg Scour and Shell Damage in the Antarctic Bivalve Laternula elliptica

PubMed Central

Harper, Elizabeth M.; Clark, Melody S.; Hoffman, Joseph I.; Philipp, Eva E. R.; Peck, Lloyd S.; Morley, Simon A.

2012-01-01

We document differences in shell damage and shell thickness in a bivalve mollusc (Laternula elliptica) from seven sites around Antarctica with differing exposures to ice movement. These range from 60% of the sea bed impacted by ice per year (Hangar Cove, Antarctic Peninsula) to those protected by virtually permanent sea ice cover (McMurdo Sound). Patterns of shell damage consistent with blunt force trauma were observed in populations where ice scour frequently occurs; damage repair frequencies and the thickness of shells correlated positively with the frequency of iceberg scour at the different sites with the highest repair rates and thicker shells at Hangar Cove (74.2% of animals damaged) compared to the other less impacted sites (less than 10% at McMurdo Sound). Genetic analysis of population structure using Amplified Fragment Length Polymorphisms (AFLPs) revealed no genetic differences between the two sites showing the greatest difference in shell morphology and repair rates. Taken together, our results suggest that L. elliptica exhibits considerable phenotypic plasticity in response to geographic variation in physical disturbance. PMID:23029484

Observation of short range order driven large refrigerant capacity in chemically disordered single phase compound Dy2Ni0.87Si2.95.

PubMed

Pakhira, Santanu; Mazumdar, Chandan; Choudhury, Dibyasree; Ranganathan, R; Giri, S

2018-05-16

In this work, we report the successful synthesis of a new intermetallic compound Dy2Ni0.87Si2.95 forming in single phase only with a chemically disordered structure. The random distribution of Ni/Si and crystal defects create a variation in the local electronic environment between the magnetic Dy ions. In the presence of both disorder and competing exchange interactions driven magnetic frustration, originating due to c/a ∼ 1, the compound undergoes spin freezing behaviour below 5.6 K. In the non-equilibrium state below the spin freezing behaviour, the compound exhibits aging phenomena and magnetic memory effects. In the magnetically short-range ordered region, much above the freezing temperature, an unusual occurrence of considerable magnetic entropy change, -ΔSmaxM ∼ 21 J kg-1 K-1 with large cooling power RCP ∼ 531 J kg-1 and adiabatic temperature change, ΔTad ∼ 10 K for a field change of 70 kOe, is observed for this short range ordered cluster-glass compound without any magnetic hysteresis loss.

Assessment of the prebiotic effect of quinoa and amaranth in the human intestinal ecosystem.

PubMed

Gullón, Beatriz; Gullón, Patricia; Tavaria, Freni K; Yáñez, Remedios

2016-09-14

Quinoa and amaranth belong to the group of the so called "superfoods" and have a nutritional composition that confers multiple benefits. In this work, we explored the possibility of these foods exhibiting a prebiotic effect. These pseudocereals were subjected to an in vitro digestion and used as carbon sources in batch cultures with faecal human inocula. The effects on the microbiota composition and their metabolic products were determined by assessment of variations in pH, short-chain fatty acid (SCFA) production and changes in the dynamic bacterial populations by fluorescence in situ hybridization (FISH). After 48 h of incubation, the total SCFAs were 106.5 mM for quinoa and 108.83 mM for amaranth, in line with the decrease in pH. Considerable differences (p < 0.05) were found in certain microbial groups, including Bifidobacterium spp., Lactobacillus-Enterococcus, Atopobium, Bacteroides-Prevotella, Clostridium coccoides-Eubacterium rectale, Faecalibacterium prausnitzii and Roseburia intestinalis. Our research suggests that these pseudocereals can have the prebiotic potential and that their intake may improve dysbiosis or maintain the gastrointestinal health through a balanced intestinal microbiota, although additional studies are necessary.

Microstructure-dependent fracture toughness (JIC) variations in dissimilar pipe welds for pressure vessel system of nuclear plants

NASA Astrophysics Data System (ADS)

Rathod, Dinesh W.; Pandey, Sunil; Singh, P. K.; Kumar, Suranjit

2017-09-01

In present study, dissimilar metal weld (DMW) joints between SA508Gr.3cl.1 ferritic steel and SS304LN pipes were prepared using Inconel 82/182, and Inconel 52/152 consumables. Metallurgical properties and their influence on fracture toughness of weldment regions and interfacial regions could play a significant role in integrity assessment of these joints. Ni-based consumables exhibit complex metallurgical properties at interfacial regions. The metallurgical characterization and fracture toughness studies of Inconel 82/182 and Inconel 52/152 joints have been carried out for determining the optimum consumable for DMW joint requirements and the effect of microstructure on fracture toughness in weldment regions. The present codes and procedures for integrity assessment of DMW joints have not given due considerations of metallurgical properties. The requirements for metallurgical properties by considering their effect on fracture toughness properties in integrity assessment have been discussed for reliable analysis. Inconel 82/182 is preferred over Inconel 52/152 joints owing to favorable metallurgical and fracture toughness properties across the interfacial and weldment regions.

Morphologic and functional implications of the surgical-orthodontic management of mandibular prognathism: a comprehensive review.

PubMed

Athanasiou, A E

1993-05-01

The aim of this review is to present the various morphologic and functional implications of the surgical-orthodontic management of mandibular prognathism, thus providing a more complete determination of the efficacy of this modality of treatment. Major conclusions that can be drawn from the bibliography indicate that: (1) After treatment considerable improvement takes place on the soft tissue and dentoskeletal profile, occlusal tooth contacts, and temporomandibular joint function and and pain; (2) Surgical management of mandibular prognathism can be associated with decreased maximum interincisal opening; (3) Although immediately after surgery there is a tendency for the condyles to be distracted downward and anteriorly from their preoperative position, in long-term postsurgery the condyles, on the average, regain their initial position; (4) Compensatory alterations in the pharyngeal, suprahyoid, and infrahyoid muscular regions take place postoperatively; (5) Skeletal changes after mandibular setback to correct mandibular prognathism occur frequently, but their magnitude and patterns exhibit variation and are not necessarily detrimental; and (6) Fulfillment of expectations toward surgical-orthodontic management of mandibular prognathism was reported to be frequent.

Towards a phylogenetic classification of Leptothecata (Cnidaria, Hydrozoa)

PubMed Central

Maronna, Maximiliano M.; Miranda, Thaís P.; Peña Cantero, Álvaro L.; Barbeitos, Marcos S.; Marques, Antonio C.

2016-01-01

Leptothecata are hydrozoans whose hydranths are covered by perisarc and gonophores and whose medusae bear gonads on their radial canals. They develop complex polypoid colonies and exhibit considerable morphological variation among species with respect to growth, defensive structures and mode of development. For instance, several lineages within this order have lost the medusa stage. Depending on the author, traditional taxonomy in hydrozoans may be either polyp- or medusa-oriented. Therefore, the absence of the latter stage in some lineages may lead to very different classification schemes. Molecular data have proved useful in elucidating this taxonomic challenge. We analyzed a super matrix of new and published rRNA gene sequences (16S, 18S and 28S), employing newly proposed methods to measure branch support and improve phylogenetic signal. Our analysis recovered new clades not recognized by traditional taxonomy and corroborated some recently proposed taxa. We offer a thorough taxonomic revision of the Leptothecata, erecting new orders, suborders, infraorders and families. We also discuss the origination and diversification dynamics of the group from a macroevolutionary perspective. PMID:26821567

Experimental infections of wild bank voles (Myodes glareolus) from nephropatia epidemica endemic and non-endemic regions revealed slight differences in Puumala virological course and immunological responses.

PubMed

Dubois, Adélaïde; Castel, Guillaume; Murri, Séverine; Pulido, Coralie; Pons, Jean-Baptiste; Benoit, Laure; Loiseau, Anne; Lakhdar, Latifa; Galan, Maxime; Charbonnel, Nathalie; Marianneau, Philippe

2017-05-02

In Europe, the occurrence of nephropathia epidemica (NE), a human disease caused by Puumala virus (PUUV), exhibits considerable geographical heterogeneity despite the continuous distribution of its reservoir, the bank vole Myodes glareolus. To better understand the causes of this heterogeneity, wild voles sampled in two adjacent NE endemic and non-endemic regions of France were infected experimentally with PUUV. The responses of bank voles to PUUV infection, based on the levels of anti-PUUV IgG and viral RNA, were compared. Slight regional differences were highlighted despite the high inter-individual variability. Voles from the NE non-endemic region showed greater immune responsiveness to PUUV infection, but lower levels of RNA in their organs than voles from the endemic region. These results suggest the existence of regional variations in the sensitivity of bank voles that could contribute to the apparent absence of PUUV circulation among voles and the absence of NE in the non-endemic region. Copyright © 2017 Elsevier B.V. All rights reserved.

Variations in the water vapor distribution and the associated effects on fog and haze events over Xi'an based on Raman lidar data and back trajectories.

PubMed

Wang, Yufeng; Zhang, Jing; Fu, Qiang; Song, Yuehui; Di, Huige; Li, Bo; Hua, Dengxin

2017-10-01

A combination of more than two years of water vapor lidar data with back trajectory analysis using the hybrid single-particle Lagrangian integrated trajectory (HYSPLIT) model was used to study the long-range transport of air masses and the water vapor distribution characteristics and variations over Xi'an, China (34.233° N, 108.911° E), which is a typical city in Northwest China. High-quality profiles of the water vapor density were derived from a multifunction Raman lidar system built in Xi'an, and more than 2000 sets of profiles with >400 nighttime observations from October 2013 to July 2016 were collected and used for statistical and quantitative analyses. The vertical variations in the water vapor content were discussed. A mutation height of the water vapor exists at 2-4 km with a high occurrence rate of ∼60% during the autumn and winter seasons. This height reflects a distinct stratification in the water vapor content. Additionally, the atmospheric water vapor content was mainly concentrated in the lower troposphere, and the proportion of the water vapor content at 0.5-5 km accounted for 80%-90% of the total water vapor below 10 km. Obvious seasonal variations were observed, including large water vapor content during the spring and summer and small content during the autumn and winter. Combined with back trajectory analysis, the results showed that markedly different water vapor transport pathways contribute to seasonal variations in the water vapor content. South and southeast airflows dominated during the summer, with 30% of the 84 trajectories originating from these areas; however, the air masses during the winter originated from the north and local regions (64.3%) and from the northwest (27%). In addition, we discussed variations in the water vapor during fog and haze weather conditions during the winter. A considerable enhancement in the mean water vapor density at 0.5-3 km exhibited a clear positive correlation (correlation coefficient >0.8) with the PM2.5 and PM10 concentrations. The results indicate that local airflow trajectories mainly affect water vapor transport below the boundary layer, and that these flows are closely related to the formation of fog and haze events in the Xi'an area.

Topical treatment of psoriasis: questionnaire results on topical therapy accessibility and influence of body surface area on usage.

PubMed

Iversen, L; Lange, M M; Bissonette, R; Carvalho, A V E; van de Kerkhof, P C; Kirby, B; Kleyn, C E; Lynde, C W; van der Walt, J M; Wu, J J

2017-07-01

Topical treatment of mild to moderate psoriasis is first-line treatment and exhibits varying degrees of success across patient groups. Key factors influencing treatment success are physician topical treatment choice (high efficacy, low adverse events) and strict patient adherence. Currently, no formalized, international consensus guidelines exist to direct optimal topical treatment, although many countries have national guidelines. To describe and analyse cross-regional variations in the use and access of psoriasis topical therapies. The study was conducted as an observational cross-sectional study. A survey was distributed to dermatologists from the International Psoriasis Council (IPC) to assess topical therapy accessibility in 26 countries and to understand how body surface area (BSA) categories guide clinical decisions on topical use. Variation in the availability of tars, topical retinoids, dithranol and balneotherapy was reported. The vast majority of respondents (100% and 88.4%) used topical therapy as first-line monotherapy in situations with BSA < 3% and BSA between 3% and 10%, respectively. However, with disease severity increasing to BSA > 10%, the number of respondents who prescribe topical therapy decreased considerably. In addition, combination therapy of a topical drug and a systemic drug was frequently reported when BSA measured >10%. This physician survey provides new evidence on topical access and the influence of disease severity on topical usage in an effort to improve treatment strategies on a global level. © 2017 European Academy of Dermatology and Venereology.

Genetic Polymorphisms Associated with Rubella Virus-Specific Cellular Immunity Following MMR Vaccination

PubMed Central

Kennedy, Richard B.; Ovsyannikova, Inna G.; Haralambieva, Iana H.; Lambert, Nathaniel D.; Pankratz, V. Shane; Poland, Gregory A.

2014-01-01

Rubella virus causes a relatively benign disease in most cases, although infection during pregnancy can result in serious birth defects. An effective vaccine has been available since the early 1970s and outbreaks typically do not occur among highly vaccinated (≥2 doses) populations. Nevertheless, considerable inter-individual variation in immune response to rubella immunization does exist, with single dose seroconversion rates ~95%. Understanding the mechanisms behind this variability may provide important insights into rubella immunity. In the current study, we examined associations between single nucleotide polymorphisms (SNPs) in selected cytokine, cytokine receptor, and innate/antiviral genes and immune responses following rubella vaccination in order to understand genetic influences on vaccine response. Our approach consisted of a discovery cohort of 887 subjects ages 11–22 at the time of enrollment and a replication cohort of 542 older adolescents and young adults (ages 18–40). Our data indicate that SNPs near the butyrophilin genes (BTN3A3/BTN2A1) and cytokine receptors (IL10RB/IFNAR1) are associated with variations in IFNγ secretion and that multiple SNPs in the PVR gene, as well as SNPs located in the ADAR gene, exhibit significant associations with rubella virus-specific IL-6 secretion. This information may be useful, not only in furthering our understanding immune responses to rubella vaccine, but also in identifying key pathways for targeted adjuvant use to boost immunity in those with weak or absent immunity following vaccination. PMID:25098560

Exploring natural variation of photosynthetic, primary metabolism and growth parameters in a large panel of Capsicum chinense accessions.

PubMed

Rosado-Souza, Laise; Scossa, Federico; Chaves, Izabel S; Kleessen, Sabrina; Salvador, Luiz F D; Milagre, Jocimar C; Finger, Fernando; Bhering, Leonardo L; Sulpice, Ronan; Araújo, Wagner L; Nikoloski, Zoran; Fernie, Alisdair R; Nunes-Nesi, Adriano

2015-09-01

Collectively, the results presented improve upon the utility of an important genetic resource and attest to a complex genetic basis for differences in both leaf metabolism and fruit morphology between natural populations. Diversity of accessions within the same species provides an alternative method to identify physiological and metabolic traits that have large effects on growth regulation, biomass and fruit production. Here, we investigated physiological and metabolic traits as well as parameters related to plant growth and fruit production of 49 phenotypically diverse pepper accessions of Capsicum chinense grown ex situ under controlled conditions. Although single-trait analysis identified up to seven distinct groups of accessions, working with the whole data set by multivariate analyses allowed the separation of the 49 accessions in three clusters. Using all 23 measured parameters and data from the geographic origin for these accessions, positive correlations between the combined phenotypes and geographic origin were observed, supporting a robust pattern of isolation-by-distance. In addition, we found that fruit set was positively correlated with photosynthesis-related parameters, which, however, do not explain alone the differences in accession susceptibility to fruit abortion. Our results demonstrated that, although the accessions belong to the same species, they exhibit considerable natural intraspecific variation with respect to physiological and metabolic parameters, presenting diverse adaptation mechanisms and being a highly interesting source of information for plant breeders. This study also represents the first study combining photosynthetic, primary metabolism and growth parameters for Capsicum to date.

Genetic polymorphisms associated with rubella virus-specific cellular immunity following MMR vaccination.

PubMed

Kennedy, Richard B; Ovsyannikova, Inna G; Haralambieva, Iana H; Lambert, Nathaniel D; Pankratz, V Shane; Poland, Gregory A

2014-11-01

Rubella virus causes a relatively benign disease in most cases, although infection during pregnancy can result in serious birth defects. An effective vaccine has been available since the early 1970s and outbreaks typically do not occur among highly vaccinated (≥2 doses) populations. Nevertheless, considerable inter-individual variation in immune response to rubella immunization does exist, with single-dose seroconversion rates ~95 %. Understanding the mechanisms behind this variability may provide important insights into rubella immunity. In the current study, we examined associations between single nucleotide polymorphisms (SNPs) in selected cytokine, cytokine receptor, and innate/antiviral genes and immune responses following rubella vaccination in order to understand genetic influences on vaccine response. Our approach consisted of a discovery cohort of 887 subjects aged 11-22 at the time of enrollment and a replication cohort of 542 older adolescents and young adults (age 18-40). Our data indicate that SNPs near the butyrophilin genes (BTN3A3/BTN2A1) and cytokine receptors (IL10RB/IFNAR1) are associated with variations in IFNγ secretion and that multiple SNPs in the PVR gene, as well as SNPs located in the ADAR gene, exhibit significant associations with rubella virus-specific IL-6 secretion. This information may be useful, not only in furthering our understanding immune responses to rubella vaccine, but also in identifying key pathways for targeted adjuvant use to boost immunity in those with weak or absent immunity following vaccination.

Combining functional weed ecology and crop stable isotope ratios to identify cultivation intensity: a comparison of cereal production regimes in Haute Provence, France and Asturias, Spain.

PubMed

Bogaard, Amy; Hodgson, John; Nitsch, Erika; Jones, Glynis; Styring, Amy; Diffey, Charlotte; Pouncett, John; Herbig, Christoph; Charles, Michael; Ertuğ, Füsun; Tugay, Osman; Filipovic, Dragana; Fraser, Rebecca

This investigation combines two independent methods of identifying crop growing conditions and husbandry practices-functional weed ecology and crop stable carbon and nitrogen isotope analysis-in order to assess their potential for inferring the intensity of past cereal production systems using archaeobotanical assemblages. Present-day organic cereal farming in Haute Provence, France features crop varieties adapted to low-nutrient soils managed through crop rotation, with little to no manuring. Weed quadrat survey of 60 crop field transects in this region revealed that floristic variation primarily reflects geographical differences. Functional ecological weed data clearly distinguish the Provence fields from those surveyed in a previous study of intensively managed spelt wheat in Asturias, north-western Spain: as expected, weed ecological data reflect higher soil fertility and disturbance in Asturias. Similarly, crop stable nitrogen isotope values distinguish between intensive manuring in Asturias and long-term cultivation with minimal manuring in Haute Provence. The new model of cereal cultivation intensity based on weed ecology and crop isotope values in Haute Provence and Asturias was tested through application to two other present-day regimes, successfully identifying a high-intensity regime in the Sighisoara region, Romania, and low-intensity production in Kastamonu, Turkey. Application of this new model to Neolithic archaeobotanical assemblages in central Europe suggests that early farming tended to be intensive, and likely incorporated manuring, but also exhibited considerable variation, providing a finer grained understanding of cultivation intensity than previously available.

Local, national, and service component cost variations in the management of low back pain: Considerations for the clinician.

PubMed

Babu, Ashwin N; McCormick, Zachary; Kennedy, David J; Press, Joel

2016-11-21

In the past two decades, the cost associated with managing low back pain has increased significantly. Improved consciousness of how clinicians utilize resources when managing low back pain is necessary in the current economic climate. The goal of this review is to examine the component costs associated with managing low back pain and provide practical solutions for reducing healthcare costs. This is accomplished by utilizing examples from a major metropolitan area with several major academic institutions and private health care centers. It is clear that there is considerable local and national variation in the component costs of managing low back pain, including physician visits, imaging studies, medications, and therapy services. By being well informed about these variations in one's environment, clinicians and patients alike can make strides towards reducing the financial impact of low back pain. Investigation of the cost discrepancies for services within one's community of practice is important. Improved public access to both cost and outcomes data is needed.

Manufacture of threads with variable pitch by using noncircular gears

NASA Astrophysics Data System (ADS)

Slătineanu, L.; Dodun, O.; Coteață, M.; Coman, I.; Nagîț, G.; Beșliu, I.

2016-08-01

There are mechanical equipments in which shafts threaded with variable pitch are included. Such a shaft could be met in the case of worm specific to the double enveloping worm gearing. Over the years, the researchers investigated some possibilities to geometrically define and manufacture the shaft zones characterized by a variable pitch. One of the methods able to facilitate the manufacture of threads with variable pitch is based on the use of noncircular gears in the threading kinematic chain for threading by cutting. In order to design the noncircular gears, the mathematical law of pitch variation has to be known. An analysis of pitch variation based on geometrical considerations was developed in the case of a double enveloping globoid worm. Subsequently, on the bases of a proper situation, a numerical model was determined. In this way, an approximately law of pitch variation was determined and it could be taken into consideration when designing the noncircular gears included in the kinematic chain of the cutting machine tool.

Morphological and genetic analysis of four color morphs of bean leaf beetle, Cerotoma trifurcata (Coleoptera: Chrysomelidae)

USDA-ARS?s Scientific Manuscript database

Bean leaf beetle (BLB) exhibits a relatively large amount of morphological variation in terms of color but little is known about the underlying genetic structure and gene flow. Genetic variation among four color phenotypes of the BLB was analyzed using amplified fragment length polymorphisms (AFLP) ...

Variation in nutrient characteristics of surface soils from the Luquillo Experimental Forest of Puerto Rico: A multivariate perspective.

Treesearch

S. B. Cox; M. R. Willig; F. N. Scatena

2002-01-01

We assessed the effects of landscape features (vegetation type and topography), season, and spatial hierarchy on the nutrient content of surface soils in the Luquillo Experimental Forest (LEF) of Puerto Rico. Considerable spatial variation characterized the soils of the LEF, and differences between replicate sites within each combination of vegetation type (tabonuco vs...

"It All Comes down to the Leadership": The Role of the School Principal in Fostering Parent-School Engagement

ERIC Educational Resources Information Center

Barr, Jenny; Saltmarsh, Sue

2014-01-01

Parent-school engagement is widely understood to be an important factor in children's school experience and educational outcomes. However, there is considerable variation in the ways that schools manage their relationships with parents, as well as variation in what parents themselves view as important for engagement with their children's…

Variation in reaction norms: Statistical considerations and biological interpretation.

PubMed

Morrissey, Michael B; Liefting, Maartje

2016-09-01

Analysis of reaction norms, the functions by which the phenotype produced by a given genotype depends on the environment, is critical to studying many aspects of phenotypic evolution. Different techniques are available for quantifying different aspects of reaction norm variation. We examine what biological inferences can be drawn from some of the more readily applicable analyses for studying reaction norms. We adopt a strongly biologically motivated view, but draw on statistical theory to highlight strengths and drawbacks of different techniques. In particular, consideration of some formal statistical theory leads to revision of some recently, and forcefully, advocated opinions on reaction norm analysis. We clarify what simple analysis of the slope between mean phenotype in two environments can tell us about reaction norms, explore the conditions under which polynomial regression can provide robust inferences about reaction norm shape, and explore how different existing approaches may be used to draw inferences about variation in reaction norm shape. We show how mixed model-based approaches can provide more robust inferences than more commonly used multistep statistical approaches, and derive new metrics of the relative importance of variation in reaction norm intercepts, slopes, and curvatures. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

Theoretical studies for the rates and kinetic isotope effects of the excited-state double proton transfer in the 1:1 7-azaindole:H2O complex using variational transition state theory including multidimensional tunneling.

PubMed

Duong, My Phu Thi; Kim, Yongho

2010-03-18

Variational transition state theory calculations including multidimensional tunneling (VTST/MT) for excited-state tautomerization in the 1:1 7-azaindole:H(2)O complex were performed. Electronic structures and energies for reactant, product, transition state, and potential energy curves along the reaction coordinate were computed at the CASSCF(10,9)/6-31G(d,p) level of theory. The potential energies were corrected by second-order multireference perturbation theory to take the dynamic electron correlation into consideration. The final potential energy curves along the reaction coordinate were generated at the MRPT2//CASSCF(10,9)/6-31G(d,p) level. Two protons in the excited-state tautomerization are transferred concertedly, albeit asynchronously. The position of the variational transition state is very different from the conventional transition state, and is highly dependent on isotopic substitution. Rate constants were calculated using VTST/MT, and were on the order of 10(-6) s(-1) at room temperature. The HH/DD kinetic isotope effects are consistent with experimental observations; consideration of both tunneling and variational effects was essential to predict the experimental values correctly.

Recognizing vocal emotions in Mandarin Chinese: a validated database of Chinese vocal emotional stimuli.

PubMed

Liu, Pan; Pell, Marc D

2012-12-01

To establish a valid database of vocal emotional stimuli in Mandarin Chinese, a set of Chinese pseudosentences (i.e., semantically meaningless sentences that resembled real Chinese) were produced by four native Mandarin speakers to express seven emotional meanings: anger, disgust, fear, sadness, happiness, pleasant surprise, and neutrality. These expressions were identified by a group of native Mandarin listeners in a seven-alternative forced choice task, and items reaching a recognition rate of at least three times chance performance in the seven-choice task were selected as a valid database and then subjected to acoustic analysis. The results demonstrated expected variations in both perceptual and acoustic patterns of the seven vocal emotions in Mandarin. For instance, fear, anger, sadness, and neutrality were associated with relatively high recognition, whereas happiness, disgust, and pleasant surprise were recognized less accurately. Acoustically, anger and pleasant surprise exhibited relatively high mean f0 values and large variation in f0 and amplitude; in contrast, sadness, disgust, fear, and neutrality exhibited relatively low mean f0 values and small amplitude variations, and happiness exhibited a moderate mean f0 value and f0 variation. Emotional expressions varied systematically in speech rate and harmonics-to-noise ratio values as well. This validated database is available to the research community and will contribute to future studies of emotional prosody for a number of purposes. To access the database, please contact pan.liu@mail.mcgill.ca.

The microgeographical patterns of morphological and molecular variation of a mixed ploidy population in the species complex Actinidia chinensis.

PubMed

Liu, Yifei; Li, Dawei; Yan, Ling; Huang, Hongwen

2015-01-01

Polyploidy and hybridization are thought to have significant impacts on both the evolution and diversification of the genus Actinidia, but the structure and patterns of morphology and molecular diversity relating to ploidy variation of wild Actinidia plants remain much less understood. Here, we examine the distribution of morphological variation and ploidy levels along geographic and environmental variables of a large mixed-ploidy population of the A. chinensis species complex. We then characterize the extent of both genetic and epigenetic diversity and differentiation exhibited between individuals of different ploidy levels. Our results showed that while there are three ploidy levels in this population, hexaploids were constituted the majority (70.3%). Individuals with different ploidy levels were microgeographically structured in relation to elevation and extent of niche disturbance. The morphological characters examined revealed clear difference between diploids and hexaploids, however tetraploids exhibited intermediate forms. Both genetic and epigenetic diversity were high but the differentiation among cytotypes was weak, suggesting extensive gene flow and/or shared ancestral variation occurred in this population even across ploidy levels. Epigenetic variation was clearly correlated with changes in altitudes, a trend of continuous genetic variation and gradual increase of epigenomic heterogeneities of individuals was also observed. Our results show that complex interactions between the locally microgeographical environment, ploidy and gene flow impact A. chinensis genetic and epigenetic variation. We posit that an increase in ploidy does not broaden the species habitat range, but rather permits A. chinensis adaptation to specific niches.

Morphological variation in Homo erectus and the origins of developmental plasticity

PubMed Central

Antón, Susan C.; Taboada, Hannah G.; Middleton, Emily R.; Rainwater, Christopher W.; Taylor, Andrea B.; Turner, Trudy R.; Turnquist, Jean E.; Weinstein, Karen J.; Williams, Scott A.

2016-01-01

Homo erectus was the first hominin to exhibit extensive range expansion. This extraordinary departure from Africa, especially into more temperate climates of Eurasia, has been variously related to technological, energetic and foraging shifts. The temporal and regional anatomical variation in H. erectus suggests that a high level of developmental plasticity, a key factor in the ability of H. sapiens to occupy a variety of habitats, may also have been present in H. erectus. Developmental plasticity, the ability to modify development in response to environmental conditions, results in differences in size, shape and dimorphism across populations that relate in part to levels of resource sufficiency and extrinsic mortality. These differences predict not only regional variations but also overall smaller adult sizes and lower levels of dimorphism in instances of resource scarcity and high predator load. We consider the metric variation in 35 human and non-human primate ‘populations’ from known environmental contexts and 14 time- and space-restricted paleodemes of H. erectus and other fossil Homo. Human and non-human primates exhibit more similar patterns of variation than expected, with plasticity evident, but in differing patterns by sex across populations. The fossil samples show less evidence of variation than expected, although H. erectus varies more than Neandertals. This article is part of the themed issue ‘Major transitions in human evolution’. PMID:27298467

Biomass-burning impact on CCN number, hygroscopicity and cloud formation during summertime in the eastern Mediterranean

NASA Astrophysics Data System (ADS)

Bougiatioti, Aikaterini; Bezantakos, Spiros; Stavroulas, Iasonas; Kalivitis, Nikos; Kokkalis, Panagiotis; Biskos, George; Mihalopoulos, Nikolaos; Papayannis, Alexandros; Nenes, Athanasios

2016-06-01

This study investigates the concentration, cloud condensation nuclei (CCN) activity and hygroscopic properties of particles influenced by biomass burning in the eastern Mediterranean and their impacts on cloud droplet formation. Air masses sampled were subject to a range of atmospheric processing (several hours up to 3 days). Values of the hygroscopicity parameter, κ, were derived from CCN measurements and a Hygroscopic Tandem Differential Mobility Analyzer (HTDMA). An Aerosol Chemical Speciation Monitor (ACSM) was also used to determine the chemical composition and mass concentration of non-refractory components of the submicron aerosol fraction. During fire events, the increased organic content (and lower inorganic fraction) of the aerosol decreases the values of κ, for all particle sizes. Particle sizes smaller than 80 nm exhibited considerable chemical dispersion (where hygroscopicity varied up to 100 % for particles of same size); larger particles, however, exhibited considerably less dispersion owing to the effects of condensational growth and cloud processing. ACSM measurements indicate that the bulk composition reflects the hygroscopicity and chemical nature of the largest particles (having a diameter of ˜ 100 nm at dry conditions) sampled. Based on positive matrix factorization (PMF) analysis of the organic ACSM spectra, CCN concentrations follow a similar trend as the biomass-burning organic aerosol (BBOA) component, with the former being enhanced between 65 and 150 % (for supersaturations ranging between 0.2 and 0.7 %) with the arrival of the smoke plumes. Using multilinear regression of the PMF factors (BBOA, OOA-BB and OOA) and the observed hygroscopicity parameter, the inferred hygroscopicity of the oxygenated organic aerosol components is determined. We find that the transformation of freshly emitted biomass burning (BBOA) to more oxidized organic aerosol (OOA-BB) can result in a 2-fold increase of the inferred organic hygroscopicity; about 10 % of the total aerosol hygroscopicity is related to the two biomass-burning components (BBOA and OOA-BB), which in turn contribute almost 35 % to the fine-particle organic water of the aerosol. Observation-derived calculations of the cloud droplet concentrations that develop for typical boundary layer cloud conditions suggest that biomass burning increases droplet number, on average by 8.5 %. The strongly sublinear response of clouds to biomass-burning (BB) influences is a result of strong competition of CCN for water vapor, which results in very low maximum supersaturation (0.08 % on average). Attributing droplet number variations to the total aerosol number and the chemical composition variations shows that the importance of chemical composition increases with distance, contributing up to 25 % of the total droplet variability. Therefore, although BB may strongly elevate CCN numbers, the impact on droplet number is limited by water vapor availability and depends on the aerosol particle concentration levels associated with the background.

Activities and prevalence of proteobacteria members colonizing Echinacea purpurea fully account for in vitro macrophage activation exhibited by extracts of this botanical

USDA-ARS?s Scientific Manuscript database

Evidence supports the theory that the bacterial communities colonizing E. purpurea contribute to the innate immune enhancing activity of this botanical. Previously we reported that only about half of the variation in in vitro monocyte stimulating activity exhibited by E. purpurea extracts could be a...

Activities and prevalence of proteobacteria members colonizing Echinacea purpurea fully account for in vitro macrophage activation exhibited by extracts of this botanical

USDA-ARS?s Scientific Manuscript database

Evidence supports the theory that bacterial communities colonizing Echinacea purpurea contribute to the innate immune enhancing activity of this botanical. Previously we reported that only about half of the variation in in vitro monocyte stimulating activity exhibited by E. purpurea extracts could ...

Concerted copy number variation balances ribosomal DNA dosage in human and mouse genomes

PubMed Central

Gibbons, John G.; Branco, Alan T.; Godinho, Susana A.; Yu, Shoukai; Lemos, Bernardo

2015-01-01

Tandemly repeated ribosomal DNA (rDNA) arrays are among the most evolutionary dynamic loci of eukaryotic genomes. The loci code for essential cellular components, yet exhibit extensive copy number (CN) variation within and between species. CN might be partly determined by the requirement of dosage balance between the 5S and 45S rDNA arrays. The arrays are nonhomologous, physically unlinked in mammals, and encode functionally interdependent RNA components of the ribosome. Here we show that the 5S and 45S rDNA arrays exhibit concerted CN variation (cCNV). Despite 5S and 45S rDNA elements residing on different chromosomes and lacking sequence similarity, cCNV between these loci is strong, evolutionarily conserved in humans and mice, and manifested across individual genotypes in natural populations and pedigrees. Finally, we observe that bisphenol A induces rapid and parallel modulation of 5S and 45S rDNA CN. Our observations reveal a novel mode of genome variation, indicate that natural selection contributed to the evolution and conservation of cCNV, and support the hypothesis that 5S CN is partly determined by the requirement of dosage balance with the 45S rDNA array. We suggest that human disease variation might be traced to disrupted rDNA dosage balance in the genome. PMID:25583482

What I experienced yesterday is who I am today: relationship of work motivations and behaviors to within-individual variation in the five-factor model of personality.

PubMed

Judge, Timothy A; Simon, Lauren S; Hurst, Charlice; Kelley, Ken

2014-03-01

Historically, organizational and personality psychologists have ignored within-individual variation in personality across situations or have treated it as measurement error. However, we conducted a 10-day experience sampling study consistent with whole trait theory (Fleeson, 2012), which conceptualizes personality as a system of stable tendencies and patterns of intraindividual variation along the dimensions of the Big Five personality traits (Costa & McCrae, 1992). The study examined whether (a) internal events (i.e., motivation), performance episodes, and interpersonal experiences at work predict deviations from central tendencies in trait-relevant behavior, affect, and cognition (i.e., state personality), and (b) there are individual differences in responsiveness to work experiences. Results revealed that personality at work exhibited both stability and variation within individuals. Trait measures predicted average levels of trait manifestation in daily behavior at work, whereas daily work experiences (i.e., organizational citizenship, interpersonal conflict, and motivation) predicted deviations from baseline tendencies. Additionally, correlations of neuroticism with standard deviations in the daily personality variables suggest that, although work experiences influence state personality, people higher in neuroticism exhibit higher levels of intraindividual variation in personality than do those who are more emotionally stable.

A Teaching Exercise to Introduce Stable Isotope Fractionation of Metals into Geochemistry Courses

ERIC Educational Resources Information Center

Weiss, Dominik J.; Harris, Caroline; Maher, Kate; Bullen, Thomas

2013-01-01

Variations in the isotopic composition of elements have been widely used to study earth's climate, biosphere, and interior, and more recently to track the fate of contaminants. Within the broad range of elements that exhibit measureable isotopic variations, metal stable isotopes are increasingly applied across the biological, geological,…

Triticum mosaic virus exhibits limited population variation yet shows evidence of parallel evolution after replicated serial passage in wheat

USDA-ARS?s Scientific Manuscript database

An infectious cDNA clone of Triticum mosaic virus (TriMV) (genus Poacevirus; family Potyviridae) was used to establish three independent lineages in wheat to examine intra-host population diversity levels within protein 1 (P1) and coat protein (CP) cistrons over time. Genetic variation was assessed ...

Effect of foam age on toxicity of pyrolysis gases from polyurethane flexible foams

NASA Technical Reports Server (NTRS)

Hilado, C. J.; Murphy, R. M.

1978-01-01

The toxicity of the pyrolysis gases from some samples of polyurethane flexible foams appears to have decreased with age, while other samples seem to exhibit no significant change with age in this respect. The changes observed were greater than could be accounted for by variations in the material, or test variations or artifacts.

A Study of Poisson's Ratio in the Yield Region

NASA Technical Reports Server (NTRS)

Gerard, George; Wildhorn, Sorrel

1952-01-01

In the yield region of the stress-strain curve the variation in Poisson's ratio from the elastic to the plastic value is most pronounced. This variation was studied experimentally by a systematic series of tests on several aluminum alloys. The tests were conducted under simple tensile and compressive loading along three orthogonal axes. A theoretical variation of Poisson's ratio for an orthotropic solid was obtained from dilatational considerations. The assumptions used in deriving the theory were examined by use of the test data and were found to be in reasonable agreement with experimental evidence.

Analysis of magnetic fields using variational principles and CELAS2 elements

NASA Technical Reports Server (NTRS)

Frye, J. W.; Kasper, R. G.

1977-01-01

Prospective techniques for analyzing magnetic fields using NASTRAN are reviewed. A variational principle utilizing a vector potential function is presented which has as its Euler equations, the required field equations and boundary conditions for static magnetic fields including current sources. The need for an addition to this variational principle of a constraint condition is discussed. Some results using the Lagrange multiplier method to apply the constraint and CELAS2 elements to simulate the matrices are given. Practical considerations of using large numbers of CELAS2 elements are discussed.

Oral infection of Aedes aegypti with yellow fever virus: geographic variation and genetic considerations.

PubMed

Tabachnick, W J; Wallis, G P; Aitken, T H; Miller, B R; Amato, G D; Lorenz, L; Powell, J R; Beaty, B J

1985-11-01

Twenty-eight populations representing a worldwide distribution of Aedes aegypti were tested for their ability to become orally infected with yellow fever virus (YFV). Populations had been analyzed for genetic variations at 11 isozyme loci and assigned to one of 8 genetic geographic groups of Ae. aegypti. Infection rates suggest that populations showing isozyme genetic relatedness also demonstrate similarity to oral infection rates with YFV. The findings support the hypothesis that genetic variation exists for oral susceptibility to YFV in Ae. aegypti.

Combining a generic process-based productivity model classification method to predict the presence and absence species in the Pacific Northwest, U.S.A

Treesearch

Nicholas C. Coops; Richard H. Waring; Todd A. Schroeder

2009-01-01

Although long-lived tree species experience considerable environmental variation over their life spans, their geographical distributions reflect sensitivity mainly to mean monthly climatic conditions.We introduce an approach that incorporates a physiologically based growth model to illustrate how a half-dozen tree species differ in their responses to monthly variation...

Computer methods for sampling from the gamma distribution

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

Johnson, M.E.; Tadikamalla, P.R.

1978-01-01

Considerable attention has recently been directed at developing ever faster algorithms for generating gamma random variates on digital computers. This paper surveys the current state of the art including the leading algorithms of Ahrens and Dieter, Atkinson, Cheng, Fishman, Marsaglia, Tadikamalla, and Wallace. General random variate generation techniques are explained with reference to these gamma algorithms. Computer simulation experiments on IBM and CDC computers are reported.

A semi-inverse variational method for generating the bound state energy eigenvalues in a quantum system: the Dirac Coulomb type-equation

NASA Astrophysics Data System (ADS)

Libarir, K.; Zerarka, A.

2018-05-01

Exact eigenspectra and eigenfunctions of the Dirac quantum equation are established using the semi-inverse variational method. This method improves of a considerable manner the efficiency and accuracy of results compared with the other usual methods much argued in the literature. Some applications for different state configurations are proposed to concretize the method.

Plasticity of Lateralization: Schooling Predicts Hand Preference but not Hand Skill Asymmetry in a Non-Industrial Society

ERIC Educational Resources Information Center

Geuze, Reint H.; Schaafsma, Sara M.; Lust, Jessica M.; Bouma, Anke; Schiefenhovel, Wulf; Groothuis, Ton G. G.

2012-01-01

Considerable variation in the frequency of left-handedness between cultures has been reported, ranging from 0.5 to 24%. This variation in hand preference may have evolved under natural or cultural selection. It has been suggested that schooling affects handedness but as in most human societies only a selected and minor part of the population does…

Regional isolation in the Balkan region: an analysis of craniofacial variation.

PubMed

Ross, Ann H

2004-05-01

Biological variation is investigated among contemporary Croatians, Bosnians, American whites, and other multitemporal Balkan populations (World War II Croatians, Macedonians, and Greeks) via multivariate statistics and distance measures of the craniofacial complex. This study demonstrates that there is considerable variation among groups of European ancestry. Bosnians and Croatians who are thought to be relatively homogenous and historically to originate from the same Slav ancestry show local variations. While environmental plasticity has been used to explain cranial changes among human groups, it does not adequately explain the variation observed between Bosnians and Croatians. It is an oversimplification to exclusively attribute the vast range of variability observed among local as well as geographic populations to environmental adaptations. Copyright 2003 Wiley-Liss, Inc.

Premaxillary crest variation within the Wukongopteridae (Reptilia, Pterosauria) and comments on cranial structures in pterosaurs.

PubMed

Cheng, Xin; Jiang, Shunxing; Wang, Xiaolin; Kellner, Alexander W A

2017-01-01

Cranial crests show considerable variation within the Pterosauria, a group of flying reptiles that developed powered flight. This includes the Wukongopteridae, a clade of non-pterodactyloids, where the presence or absence of such head structures, allied with variation in the pelvic canal, have been regarded as evidence for sexual dimorphism. Here we discuss the cranial crest variation within wukongopterids and briefly report on a new specimen (IVPP V 17957). We also show that there is no significant variation in the anatomy of the pelvis of crested and crestless specimens. We further revisit the discussion regarding the function of cranial structures in pterosaurs and argue that they cannot be dismissed a priori as a valuable tool for species recognition.

On the variability of LSI+61 deg 303 (identical with GT 0236)

NASA Technical Reports Server (NTRS)

Tanzi, E. G.; Bignami, G. F.; Caraveo, P. A.; Maraschi, L.; Sormani, F.; Treves, A.

1982-01-01

Out of six long and six short wavelength observations, one spectrum exhibits a significant photometric variation: or approximately 20%. Interpreting the continuum as due to superposition of an early B main sequence star plus a gaseous component contributing at lambda 2000 A, the wavelength dependence of the variation suggests that it derives from the latter component. The data indicate that if the observed variation is phase dependent, a minimum should occur between phases 0.8 and 0.2. However, since the variation is observed in only one spectrum, it may well be erratic.

Thermal tolerance breadths among groundwater crustaceans living in a thermally constant environment.

PubMed

Mermillod-Blondin, F; Lefour, C; Lalouette, L; Renault, D; Malard, F; Simon, L; Douady, C J

2013-05-01

The climate variability hypothesis assumes that the thermal tolerance breadth of a species is primarily determined by temperature variations experienced in its environment. If so, aquatic invertebrates living in thermally buffered environments would be expected to exhibit narrow thermal tolerance breadths (stenothermy). We tested this prediction by studying the thermal physiology of three isopods (Asellidae, Proasellus) colonizing groundwater habitats characterized by an annual temperature amplitude of less than 1°C. The species responses to temperature variation were assessed in the laboratory using five physiological variables: survival, locomotor activity, aerobic respiration, immune defense and concentrations of total free amino acids and sugars. The three species exhibited contrasted thermal physiologies, although all variables were not equally informative. In accordance with the climate variability hypothesis, two species were extremely sensitive even to moderate changes in temperature (2°C) below and above their habitat temperature. In contrast, the third species exhibited a surprisingly high thermal tolerance breadth (11°C). Differences in response to temperature variation among Proasellus species indicated that their thermal physiology was not solely shaped by the current temperature seasonality in their natural habitats. More particularly, recent gene flow among populations living in thermally constant yet contrasted habitats might explain the occurrence of eurytherm species in thermally buffered environments.

Visualizing Intrapopulation Hematopoietic Cell Heterogeneity with Self-Organizing Maps of SIMS Data.

PubMed

Mirshafiee, Vahid; Harley, Brendan A C; Kraft, Mary L

2018-05-07

Characterization of the heterogeneity within stem cell populations, which affects their differentiation potential, is necessary for the design of artificial cultures for stem cell expansion. In this study, we assessed whether self-organizing maps (SOMs) of single-cell time-of-flight secondary ion mass spectrometry (TOF-SIMS) data provide insight into the spectral, and thus the related functional heterogeneity between and within three hematopoietic cell populations. SOMs were created of TOF-SIMS data from individual hematopoietic stem and progenitor cells (HSPCs), lineage-committed common lymphoid progenitors (CLPs), and fully differentiated B cells that had been isolated from murine bone marrow via conventional flow cytometry. The positions of these cells on the SOMs and the spectral variation between adjacent map units, shown on the corresponding unified distance matrix (U-matrix), indicated the CLPs exhibited the highest intrapopulation spectral variation, regardless of the age of the donor mice. SOMs of HSPCs, CLPs, and B cells isolated from young and old mice using the same surface antigen profiles revealed the HSPCs exhibited the most age-related spectral variation, whereas B cells exhibited the least. These results demonstrate that SOMs of single-cell spectra enable characterizing the heterogeneity between and within cell populations that lie along distinct differentiation pathways.

Information theory and the neuropeptidergic regulation of seasonal reproduction in mammals and birds

PubMed Central

Stevenson, Tyler J.; Ball, Gregory F.

2011-01-01

Seasonal breeding in the temperate zone is a dramatic example of a naturally occurring change in physiology and behaviour. Cues that predict periods of environmental amelioration favourable for breeding must be processed by the brain so that the appropriate responses in reproductive physiology can be implemented. The neural integration of several environmental cues converges on discrete hypothalamic neurons in order to regulate reproductive physiology. Gonadotrophin-releasing hormone-1 (GnRH1) and Kisspeptin (Kiss1) neurons in avian and mammalian species, respectively, show marked variation in expression that is positively associated with breeding state. We applied the constancy/contingency model of predictability to investigate how GnRH1 and Kiss1 integrate different environmental cues to regulate reproduction. We show that variation in GnRH1 from a highly seasonal avian species exhibits a predictive change that is primarily based on contingency information. Opportunistic species have low measures of predictability and exhibit a greater contribution of constancy information that is sex-dependent. In hamsters, Kiss1 exhibited a predictive change in expression that was predominantly contingency information and is anatomically localized. The model applied here provides a framework for studies geared towards determining the impact of variation in climate patterns to reproductive success in vertebrate species. PMID:21208957

Comparison of storm-time changes of geomagnetic field at ground and at MAGSAT altitudes, part 3

NASA Technical Reports Server (NTRS)

Dejesusparada, N. (Principal Investigator); Kane, R. P.; Trivedi, N. B.

1982-01-01

The latitudinal distributions of delta H, delta X, delta Y, and delta Z were studied for quiet and disturbed periods. For quiet periods, the average patterns showed some variations common to dusk and dawn, thus indicating probable ground anomaly. However, there were significant differences too between dusk and dawn, indicating considerable diurnal variation effects. Particularly in delta Y, these effects were large and were symmetric about the dip equator. For disturbed day passes, the quiet day patterns were considered as base levels and the latter were subtracted from the former. The resulting residual latitudinal patterns were, on the average, symmetric about the geographical equator. However, individual passes showed considerable north-south asymmetries, probably indicating meanderings of the central plane of the magnetospheric ring current.

Estimates of annual survival, growth, and recruitment of a white-tailed ptarmigan population in Colorado over 43 years

USGS Publications Warehouse

Wann, Greg; Aldridge, Cameron L.; Braun, Clait E.

2014-01-01

Long-term datasets for high-elevation species are rare, and considerable uncertainty exists in understanding how high-elevation populations have responded to recent climate warming. We present estimates of demographic vital rates from a 43-year population study of white-tailed ptarmigan (Lagopus leucura), a species endemic to alpine habitats in western North America. We used capture-recapture models to estimate annual rates of apparent survival, population growth, and recruitment for breeding-age ptarmigan, and we fit winter weather covariates to models in an attempt to explain annual variation. There were no trends in survival over the study period but there was strong support for age and sex effects. The average rate of annual growth suggests a relatively stable breeding-age population ( λ ¯ = 1.036), but there was considerable variation between years for both population growth and recruitment rates. Winter weather covariates only explained a small amount of variation in female survival and were not an important predictor of male survival. Cumulative winter precipitation was found to have a quadratic effect on female survival, with survival being highest during years of average precipitation. Cumulative winter precipitation was positively correlated with population growth and recruitment rates, although this covariate only explained a small amount of annual variation in these rates and there was considerable uncertainty among the models tested. Our results provide evidence for an alpine-endemic population that has not experienced extirpation or drastic declines. However, more information is needed to understand risks and vulnerabilities of warming effects on juveniles as our analysis was confined to determination of vital rates for breeding-age birds.

Educational Attainment by Age, Sex, and Race, for the United States: 1970. 1970 Census of Population, Supplementary Report.

ERIC Educational Resources Information Center

Bureau of the Census (DOC), Suitland, MD. Population Div.

The 1960's witnessed considerable change in educational attainment levels. Of Americans 25 years old and over in 1970, 52 percent were at least high school graduates, as compared with 41 percent in 1960 and 34 percent in 1950. There was considerable variation in educational attainment levels in 1970 among the various age groups in the population.…

Bold Colors in a Cryptic Lineage: Do Eastern Indigo Snakes Exhibit Color Dimorphism?

PubMed Central

Deitloff, Jennifer; Johnson, Valerie M.; Guyer, Craig

2013-01-01

Many species exhibit variation in the color of their scales, feathers, or fur. Various forms of natural selection, such as mimicry, crypsis, and species recognition, as well as sexual selection, can influence the evolution of color. Eastern Indigo Snakes (Drymarchon couperi), a federally threatened species, have coloration on the sides of the head and the chin that can vary from black to red or cream. Despite significant conservations efforts for this species, little is known about its biology in the field. Past researchers have proposed that the color variation on the head and chin is associated with the sex of the individual. Alternatively, color might vary among individuals because it is controlled by genes that are under natural selection or neutral evolution. We tested these alternative hypotheses by examining whether coloration of the sublabial, submaxillary, and ventral scales of this species differed by sex or among clutches. We used color spectrometry to characterize important aspects of color in two ways: by examining overall color differences across the entire color spectrum and by comparing differences within the ultraviolet, yellow, and red colorbands. We found that Eastern Indigo Snakes do not exhibit sexual dichromatism, but their coloration does vary among clutches; therefore, the pattern of sexual selection leading to sexual dichromatism observed in many squamates does not appear to play a role in the evolution and maintenance of color variation in Eastern Indigo Snakes. We suggest that future studies should focus on determining whether color variation in these snakes is determined by maternal effects or genetic components and if color is influenced by natural selection or neutral evolutionary processes. Studying species that exhibit bright colors within lineages that are not known for such coloration will contribute greatly to our understanding of the evolutionary and ecological factors that drive these differences. PMID:23691245

Considerations for the effects of military deployment on children and families.

PubMed

Lincoln, Alan J; Sweeten, Kathie

2011-01-01

Children of deployed military personnel represent a unique subculture in the United States. While many children exhibit high levels of resiliency, others will struggle with the impact of a parent who has gone to war. This article looks at some of the stressors of deployment as experienced by children and offers three case examples as well as clinical considerations for those who work with the children and families of the deployed.

Magnetic properties of intermetallic compounds La(Ni,Co,Cu)3

NASA Astrophysics Data System (ADS)

Tazuke, Y.; Tanikawa, H.; Okano, A.; Miyaji, T.

2006-09-01

LaNi3 exhibited a metallic antiferromagnetic property with T N = 30 K. La(Ni1-x Cox )3 with x = 0.01, 0.03 and 0.05 exhibited ferromagnetic properties, T C increasing linearly with increasing x . La(Ni1-2z Coz Cuz )3 with z = 0.015 exhibited a ferromagnetic property with a small T C. A La(Ni1-y Cuy )3 sample with y = 0.01 exhibited a Pauli-paramagnetic property; those with y = 0.02, 0.03 and 0.04 exhibited gradual metamagnetic behavior and that with y = 0.05 exhibited a ferromagnetic property. The gradual metamagnetic M -H variations are numerically simulated by using Landau-type free energies. The results suggest that the gradual metamagnetic behavior occurs from an antiferromagnetic state to a ferromagnetic one.

Plumage development and molt in Long-tailed Manakins (Chiroxiphia linearis): Variation according to sex and age

USGS Publications Warehouse

Doucet, S.M.; McDonald, D.B.; Foster, M.S.; Clay, R.P.

2007-01-01

Lek-mating Long-tailed Manakins (Chiroxiphia linearis) exhibit an unusual pattern of delayed plumage maturation. Each year, males progress through a series of predefinitive plumages before attaining definitive plumage in their fifth calendar year. Females also exhibit variation in plumage coloration, with some females displaying male-like plumage characteristics. Using data from mist-net captures in northwest Costa Rica (n = 1,315) and museum specimens from throughout the range of Long-tailed Manakins (n = 585), we documented the plumage sequence progression of males, explored variation in female plumage, and described the timing of molt in this species. Males progressed through a series of age-specific predefinitive plumages, which enabled the accurate aging of predefinitive-plumaged males in the field; this predefinitive plumage sequence is the basis for age-related status-signaling in these males. Females tended to acquire red coloration in the crown as they aged. However, colorful plumage in females may be a byproduct of selection on bright male plumage. Females exhibited an early peak of molt activity from February to April, little molt from May through July, and a second, more pronounced peak of molt activity in October. By contrast, males in older predefinitive-plumage stages and males in definitive plumage exhibited comparable unimodal distributions in molt activity beginning in June and peaking between July and October. Our data are consistent with selective pressure to avoid the costs of molt-breeding overlap in females and older males. Our findings have important implications for social organization and signaling in Long- tailed Manakins, and for the evolution of delayed plumage maturation in birds.

Late Reduction Textures in Almahata Sitta Ureilite

NASA Technical Reports Server (NTRS)

Herrin, J. S.; Le, L.; Zolensky, M. E.; Ito, M.; Jenniskens, P.; Shaddad, M. H.

2009-01-01

The Almahata Sitta ureilite, derived from asteroid 2008 TC3, consists of many individual fragments recovered from the Nubian dessert strewn field [1]. Like most ureilites, it contains abundant carbon and exhibits examples of disequilibrium textures that record a late reduction event accompanied by rapid cooling (tens of degC/h) from high temperatures (1150-1300 C). Variations in Fe/Mg of silicate minerals are accompanied by variations in Fe/Mn, indicating loss of Fe into metal [2]. In coarser-grained fragments of Almahata Sitta, olivine exhibits irregular high mg# rims in contact with networks of interstitial metal 5- 20 microns in typical thickness. This is a common ureilite texture thought to be driven by the reaction of graphite to a CO gas phase and the concurrent reduction of FeO in olivine to Fe metal, with excess silica going primarily into pyroxene (2MgFeSiO4 + C approaches MgSiO4 + MgSiO3 + 2Fe + CO) [3, see also 4,5,6]. Other fragments of Almahata Sitta exhibit anomalous textures such as fine grain size, high porosity, and abundant graphite. Within these fragments pyroxene locally exhibits high-mg# rims in contact with metal and a discreet silica phase, suggesting that the reduction mechanism MgFeSi2O6 + C approaches MgSiO3 + Fe + SiO2 + CO. Metals in Almahata Sitta are particularly unaltered in comparison to ureilite finds. Variations in minor and trace element composition of this metal might partly result from localized dilution as iron is supplied by reduction of silicates.

Determining the effects of dams on subdaily variation in river flows at a whole-basin scale

USGS Publications Warehouse

Zimmerman, J.K.H.; Letcher, B.H.; Nislow, K.H.; Lutz, K.A.; Magilligan, F.J.

2010-01-01

River regulation can alter the frequency and magnitude of subdaily flow variations causing major impacts on ecological structure and function. We developed an approach to quantify subdaily flow variation for multiple sites across a large watershed to assess the potential impacts of different dam operations (flood control, run-of-river hydropower and peaking hydropower) on natural communities. We used hourly flow data over a 9-year period from 30 stream gages throughout the Connecticut River basin to calculate four metrics of subdaily flow variation and to compare sites downstream of dams with unregulated sites. Our objectives were to (1) determine the temporal scale of data needed to characterize subdaily variability; (2) compare the frequency of days with high subdaily flow variation downstream of dams and unregulated sites; (3) analyse the magnitude of subdaily variation at all sites and (4) identify individual sites that had subdaily variation significantly higher than unregulated locations. We found that estimates of flow variability based on daily mean flow data were not sufficient to characterize subdaily flow patterns. Alteration of subdaily flows was evident in the number of days natural ranges of variability were exceeded, rather than in the magnitude of subdaily variation, suggesting that all rivers may exhibit highly variable subdaily flows, but altered rivers exhibit this variability more frequently. Peaking hydropower facilities had the most highly altered subdaily flows; however, we observed significantly altered ranges of subdaily variability downstream of some flood-control and run-of-river hydropower dams. Our analysis can be used to identify situations where dam operating procedures could be modified to reduce the level of hydrologic alteration. ?? 2009 John Wiley & Sons, Ltd.

Spatiotemporal variation of radon and carbon dioxide concentrations in an underground quarry: coupled processes of natural ventilation, barometric pumping and internal mixing.

PubMed

Perrier, Frédéric; Richon, Patrick

2010-04-01

Radon-222 and carbon dioxide concentrations have been measured during several years at several points in the atmosphere of an underground limestone quarry located at a depth of 18 m in Vincennes, near Paris, France. Both concentrations showed a seasonal cycle. Radon concentration varied from 1200 to 2000 Bq m(-3) in summer to about 800-1400 Bq m(-3) in winter, indicating winter ventilation rates varying from 0.6 to 2.5 x 10(-6) s(-1). Carbon dioxide concentration varied from 0.9 to 1.0% in summer, to about 0.1-0.3% in winter. Radon concentration can be corrected for natural ventilation using temperature measurements. The obtained model also accounts for the measured seasonal variation of carbon dioxide. After correction, radon concentrations still exhibit significant temporal variation, mostly associated with the variation of atmospheric pressure, with coupling coefficients varying from -7 to -26 Bq m(-3) hPa(-1). This variation can be accounted for using a barometric pumping model, coupled with natural ventilation in winter, and including internal mixing as well. After correction, radon concentrations exhibit residual temporal variation, poorly correlated between different points, with standard deviations varying from 3 to 6%. This study shows that temporal variation of radon concentrations in underground cavities can be understood to a satisfactory level of detail using non-linear and time-dependent modelling. It is important to understand the temporal variation of radon concentrations and the limitations in their modelling to monitor the properties of natural or artificial underground settings, and to be able to assess the existence of new processes, for example associated with the preparatory phases of volcanic eruptions or earthquakes. Copyright 2009 Elsevier Ltd. All rights reserved.

Educational inequalities in self-rated health across US states and European countries.

PubMed

Präg, Patrick; Subramanian, S V

2017-07-01

The US shows a distinct health disadvantage when compared to other high-income nations. A potential lever to reduce this disadvantage is to improve the health situation of lower socioeconomic groups. Our objective is to explore how the considerable within-US variation in health inequalities compares to the health inequalities across other Western countries. Representative survey data from 44 European countries and the US federal states were obtained from the fourth wave of the European Values Study (EVS) and the 2008 wave of the Behavioral Risk Factor Surveillance System. Using binary logistic regression, we analyze different forms of educational inequalities in self-rated health (SRH), adjusted for age and sex. The extent of educational inequalities in SRH varies considerably over European countries and US states; with US states in general showing greater inequality, however, differences between US states and European countries are less clear than commonly assumed. The US has considerable differences in educational inequalities in SRH across geographic locations. To understand the reasons for the US health disadvantage, comparative research has to take into account the vast variation in health inequalities within the US.

Nickel-silver composition shows promise as catalyst for hydrogen-oxygen fuel cells

NASA Technical Reports Server (NTRS)

Magerl, J. A.; Murray, J. N.

1970-01-01

Carburized 3-1 nickel-silver preparation exhibits considerable catalytic activity, although not as high as platinum black. Cost and availability factors warrant further evaluation of nickel-silver materials.

Sodium ion channel alkaloid resistance does not vary with toxicity in aposematic Dendrobates poison frogs: An examination of correlated trait evolution

PubMed Central

Wang, Ian J.

2018-01-01

Spatial heterogeneity in the strength or agents of selection can lead to geographic variation in ecologically important phenotypes. Many dendrobatid frogs sequester alkaloid toxins from their diets and often exhibit fixed mutations at NaV1.4, a voltage-gated sodium ion channel associated with alkaloid toxin resistance. Yet previous studies have noted an absence of resistance mutations in individuals from several species known to sequester alkaloid toxins, suggesting possible intraspecific variation for alkaloid resistance in these species. Toxicity and alkaloid profiles vary substantially between populations in several poison frog species (genus Dendrobates) and are correlated with variation in a suite of related traits such as aposematic coloration. If resistance mutations are costly, due to alterations of channel gating properties, we expect that low toxicity populations will have reduced frequencies and potentially even the loss of resistance alleles. Here, we examine whether intraspecific variation in toxicity in three dendrobatid frogs is associated with intraspecific variation in alleles conferring toxin resistance. Specifically, we examine two species that display marked variation in toxicity throughout their native ranges (Dendrobates pumilio and D. granuliferus) and one species with reduced toxicity in its introduced range (D. auratus). However, we find no evidence for population-level variation in alkaloid resistance at NaV1.4. In fact, contrary to previous studies, we found that alkaloid resistance alleles were not absent in any populations of these species. All three species exhibit fixed alkaloid resistance mutations throughout their ranges, suggesting that these mutations are maintained even when alkaloid sequestration is substantially reduced. PMID:29534110

Mycelial growth rate and toxin production in the seed pathogen Pyrenophora semeniperda: Resource trade-offs and temporally varying selection

Treesearch

S. E. Meyer; M. Masi; S. Clement; T. L. Davis; J. Beckstead

2015-01-01

Pyrenophora semeniperda, an important pathogen in Bromus tectorum seed banks in semi-arid western North America, exhibits >4-fold variation in mycelial growth rate. Host seeds exhibit seasonal changes in dormancy that affect the risk of pathogen-caused mortality. The hypothesis tested is that contrasting seed dormancy phenotypes select for contrasting strategies...

New Synthesis Of Poly(1,3,4-Oxadiazoles)

NASA Technical Reports Server (NTRS)

Connell, John W.; Hergenrother, Paul M.; Wolf, Peter

1992-01-01

Synthesis via aromatic nucleophilic displacement yields new high-molecular-weight polymers. Polymers exhibited good mechanical and thermal properties. Synthetic route provided high-molecular-weight POX of new chemical structure, potentially more economical. Availability of large variety of activated aromatic dihalides, facilitates variation of chemical structures. Exhibit properties making them useful as films. Also useful in coatings, adhesives, moldings, and composites.

Oxidative potential of ambient PM2.5 in the coastal cities of the Bohai Sea, northern China: Seasonal variation and source apportionment.

PubMed

Liu, WeiJian; Xu, YunSong; Liu, WenXin; Liu, QingYang; Yu, ShuangYu; Liu, Yang; Wang, Xin; Tao, Shu

2018-05-01

Emissions of air pollutants from primary and secondary sources in China are considerably higher than those in developed countries, and exposure to air pollution is main risk of public health. Identifying specific particulate matter (PM) compositions and sources are essential for policy makers to propose effective control measures for pollutant emissions. Ambient PM 2.5 samples covered a whole year were collected from three coastal cities of the Bohai Sea. Oxidative potential (OP) was selected as the indicator to characterize associated PM compositions and sources most responsible for adverse impacts on human health. Positive matrix factorization (PMF) and multiple linear regression (MLR) were employed to estimate correlations of PM 2.5 sources with OP. The volume- and mass-based dithiothreitol (DTT v and DTT m ) activities of PM 2.5 were significantly higher in local winter or autumn (p < 0.01). Spatial and seasonal variations in DTT v and DTT m were much larger than mass concentrations of PM 2.5 , indicated specific chemical components are responsible for PM 2.5 derived OP. Strong correlations (r > 0.700, p < 0.01) were found between DTT activity and water-soluble organic carbon (WSOC) and some transition metals. Using PMF, source fractions of PM 2.5 were resolved as secondary source, traffic source, biomass burning, sea spray and urban dust, industry, coal combustion, and mineral dust. Further quantified by MLR, coal combustion, biomass burning, secondary sources, industry, and traffic source were dominant contributors to the water-soluble DTT v activity. Our results also suggested large differences in seasonal contributions of different sources to DTT v variability. A higher contribution of DTT v was derived from coal combustion during the local heating period. Secondary sources exhibited a greater fraction of DTT v in summer, when there was stronger solar radiation. Traffic sources exhibited a prevailing contribution in summer, and industry contributed larger proportions in spring and winter. Future abatement priority of air pollution should reduce the sources contributing to OP of PM 2.5 . Copyright © 2018 Elsevier Ltd. All rights reserved.

A Water Balance Approach to Characterizing the Hydroclimatology of a Mountainous Semi-arid Catchment

NASA Astrophysics Data System (ADS)

Chauvin, G.; Flerchinger, G.; Marks, D.; Link, T.

2004-12-01

A long-term water balance is needed to understand the hydrology of mountainous semi-arid catchments, which exhibit considerable interannual variability in precipitation and temperature as well as spatial variation in snow accumulation, soils, and vegetation. Long-term data sets reduce the uncertainty associated with estimating water balance quantities that are difficult to measure in practice. In this study, the data required to compute a long-term water balance are assembled from on-site and nearby locations to create a continuous 21-year hourly record of precipitation, meteorological parameters, and streamflow for the Upper Sheep Creek (USC) catchment, a 26 ha, snow-fed, semi-arid rangeland headwater drainage within the Reynolds Creek Experimental Watershed in southwestern Idaho, USA. This study will allow us to extend a previous 10-year water balance (water years 1985-1994) computed for the USC catchment, enabling a more thorough consideration of climate variability including periods of drought and flood. It also sets the stage for analyzing the hydrologic response of the USC catchment to a prescribed fire planned for 2006. Statistical correlations between on-site and nearby meteorological stations were used to develop a complete 21-year hourly data set (water years 1984-2004) of climate and precipitation records. These data will be used to drive the Simultaneous Heat and Water (SHAW) model to simulate evaporation and transpiration, precipitation, storage, and stream discharge. Water balance quantities will be computed for separate landscape units and then aggregated for the overall watershed. This research will improve our ability to manage water resources in semi-arid mountain regions.

New Statistical Model for Variability of Aerosol Optical Thickness: Theory and Application to MODIS Data over Ocean

NASA Technical Reports Server (NTRS)

Alexandrov, Mikhail Dmitrievic; Geogdzhayev, Igor V.; Tsigaridis, Konstantinos; Marshak, Alexander; Levy, Robert; Cairns, Brian

2016-01-01

A novel model for the variability in aerosol optical thickness (AOT) is presented. This model is based on the consideration of AOT fields as realizations of a stochastic process, that is the exponent of an underlying Gaussian process with a specific autocorrelation function. In this approach AOT fields have lognormal PDFs and structure functions having the correct asymptotic behavior at large scales. The latter is an advantage compared with fractal (scale-invariant) approaches. The simple analytical form of the structure function in the proposed model facilitates its use for the parameterization of AOT statistics derived from remote sensing data. The new approach is illustrated using a month-long global MODIS AOT dataset (over ocean) with 10 km resolution. It was used to compute AOT statistics for sample cells forming a grid with 5deg spacing. The observed shapes of the structure functions indicated that in a large number of cases the AOT variability is split into two regimes that exhibit different patterns of behavior: small-scale stationary processes and trends reflecting variations at larger scales. The small-scale patterns are suggested to be generated by local aerosols within the marine boundary layer, while the large-scale trends are indicative of elevated aerosols transported from remote continental sources. This assumption is evaluated by comparison of the geographical distributions of these patterns derived from MODIS data with those obtained from the GISS GCM. This study shows considerable potential to enhance comparisons between remote sensing datasets and climate models beyond regional mean AOTs.

Altered sleep and affect in the neurotensin receptor 1 knockout mouse.

PubMed

Fitzpatrick, Karrie; Winrow, Christopher J; Gotter, Anthony L; Millstein, Joshua; Arbuzova, Janna; Brunner, Joseph; Kasarskis, Andrew; Vitaterna, Martha H; Renger, John J; Turek, Fred W

2012-07-01

Sleep and mood disorders have long been understood to have strong genetic components, and there is considerable comorbidity of sleep abnormalities and mood disorders, suggesting the involvement of common genetic pathways. Here, we examine a candidate gene implicated in the regulation of both sleep and affective behavior using a knockout mouse model. Previously, we identified a quantitative trait locus (QTL) for REM sleep amount, REM sleep bout number, and wake amount in a genetically segregating population of mice. Here, we show that traits mapping to this QTL correlated with an expression QTL for neurotensin receptor 1 (Ntsr1), a receptor for neurotensin, a ligand known to be involved in several psychiatric disorders. We examined sleep as well as behaviors indicative of anxiety and depression in the NTSR1 knockout mouse. NTSR1 knockouts had a lower percentage of sleep time spent in REM sleep in the dark phase and a larger diurnal variation in REM sleep duration than wild types under baseline conditions. Following sleep deprivation, NTSR1 knockouts exhibited more wake and less NREM rebound sleep. NTSR1 knockouts also showed increased anxious and despair behaviors. Here we illustrate a link between expression of the Ntsr1 gene and sleep traits previously associated with a particular QTL. We also demonstrate a relationship between Ntsr1 and anxiety and despair behaviors. Given the considerable evidence that anxiety and depression are closely linked with abnormalities in sleep, the data presented here provide further evidence that neurotensin and Ntsr1 may be a component of a pathway involved in both sleep and mood disorders.

Genetic variation in carbon isotope discrimination and its relationship to growth under field conditions in full-sib families of Picea mariana

Treesearch

Lawrence B. Flanagan; Kurt H. Johnsen

1995-01-01

Measurements of the stable carbon isotope composition of leaf tissue were made on Picea mariana (Mill.) B.S.P. trees from four full-sib families grown on three different field sites at the Petawawa National Forestry Institute, Ontario, Canada. The four families chosen exhibited genetic variation for growth characteristics. Genetic...

Education as Experimentation: A Planned Variation Model. Volume IV-E. Supplementary Analyses: Reanalysis of Selected Data Sets. Volume IV-F. Supplementary Analyses: Appendix.

ERIC Educational Resources Information Center

Proper, Elizabeth C.; And Others

This segment of the national evaluation study of the Follow Through Planned Variation Model discusses findings of analyses of achievement test data which have been adjusted to take into consideration the preschool experience of children in three Follow Through cohorts. These analyses serve as a supplement to analyses presented in Volume IV-A of…

Marine stratocumulus structure

NASA Technical Reports Server (NTRS)

Cahalan, Robert F.; Snider, Jack B.

1989-01-01

Thirty-three Landsat TM scenes of California stratocumulus cloud fields were acquired as part of the FIRE Marine Stratocumulus Intensive Field Observations in July 1987. They exhibit a wide variety of stratocumulus structures. Analysis has so far focused upon the July 7 scene, in which aircraft from NASA, NCAR, and the British Meteorological Office repeatedly gathered data across a stratocumulus-fair weather cumulus transition. The aircraft soundings validate the cloud base temperature threshold determined by spatial coherence analysis of the TM thermal band. Brightness variations in the stratocumulus region exhibit a -5/3 power-law decrease of the wavenumber spectra for scales larger than the cloud thickness, about 200 m, changing to a -3 power at smaller scales. Observations by an upward-looking three-channel microwave radiometer on San Nicolas Island also show the -5/3 power-law in total integrated liquid water, suggesting that the largest-scale TM brightness variations are primarily due to variations in the liquid water. The Kolmogorov 5/3 power suggests that for some purposes liquid water in turbulent stratocumulus clouds may be treated as a passive scalar, simply reflecting variations in vertical velocity. This may be tested using the velocities measured by the aircraft.

Genetic Structure of First Nation Communities in the Pacific Northwest.

PubMed

Hughes, Cris E; Rogers, Mary P; Owings, Amanda C; Petzelt, Barbara; Mitchell, Joycelynn; Harry, Harold; Williams, Theresa; Goldberg, Dena; Labuda, Damian; Smith, David Glenn; Cybulski, Jerome S; Malhi, Ripan S

2016-10-01

This study presents genetic data for nine Native American populations from northern North America. Analyses of genetic variation focus on the Pacific Northwest (PNW). Using mitochondrial, Y chromosomal, and autosomal DNA variants, we aimed to more closely address the relationships of geography and language with present genetic diversity among the regional PNW Native American populations. Patterns of genetic diversity exhibited by the three genetic systems were consistent with our hypotheses: genetic variation was more strongly explained by geographic proximity than by linguistic structure. Our findings were corroborated through a variety on analytic approaches, with the unrooted trees for the three genetic systems consistently separating inland from coastal PNW populations. Furthermore, analyses of molecular variance support the trends exhibited by the unrooted trees, with geographic partitioning of PNW populations (F CT = 19.43%, p = 0.010 ± 0.009) accounting for over twice as much of the observed genetic variation as linguistic partitioning of the same populations (F CT = 9.15%, p = 0.193 ± 0.013). These findings demonstrate a consensus with previous PNW population studies examining the relationships of genome-wide variation, mitochondrial haplogroup frequencies, and skeletal morphology with geography and language.

Clock gene evolution: seasonal timing, phylogenetic signal, or functional constraint?

PubMed

Krabbenhoft, Trevor J; Turner, Thomas F

2014-01-01

Genetic determinants of seasonal reproduction are not fully understood but may be important predictors of organism responses to climate change. We used a comparative approach to study the evolution of seasonal timing within a fish community in a natural common garden setting. We tested the hypothesis that allelic length variation in the PolyQ domain of a circadian rhythm gene, Clock1a, corresponded to interspecific differences in seasonal reproductive timing across 5 native and 1 introduced cyprinid fishes (n = 425 individuals) that co-occur in the Rio Grande, NM, USA. Most common allele lengths were longer in native species that initiated reproduction earlier (Spearman's r = -0.70, P = 0.23). Clock1a allele length exhibited strong phylogenetic signal and earlier spawners were evolutionarily derived. Aside from length variation in Clock1a, all other amino acids were identical across native species, suggesting functional constraint over evolutionary time. Interestingly, the endangered Rio Grande silvery minnow (Hybognathus amarus) exhibited less allelic variation in Clock1a and observed heterozygosity was 2- to 6-fold lower than the 5 other (nonimperiled) species. Reduced genetic variation in this functionally important gene may impede this species' capacity to respond to ongoing environmental change.

East Europe Report. Economic and Industrial Affairs No. 2437.

DTIC Science & Technology

1983-08-17

considerable attention at exhibitions in Hungary, including also the Budapest International Fair. The showroom that opened this year on Ors Vezer Square...quickly became popular. One reason for this is the display of Soviet cars. What role do you intend to assign the showroom in the future, and what...exhibitions will be held there? [Answer] The showroom for displaying Soviet commodities features 450 square meters of floorspace and 600 square meters of

Socio-demographic diversity and unexplained variation in death rates among the most deprived parliamentary constituencies in Britain.

PubMed

Tunstall, H; Mitchell, R; Gibbs, J; Platt, S; Dorling, D

2012-06-01

There is considerable unexplained variation in death rates between deprived areas of Britain. This analysis assesses the degree of variation in socio-demographic factors among deprivation deciles and how variables associated with deaths differ among the most deprived areas. Death rates 1996-2001, Carstairs' 2001 deprivation score and indicators, population density, black and minority ethnic group (BME) and population change 1971-2001 were calculated for 641 parliamentary constituencies in Britain. Constituencies were grouped into Carstairs' deciles. We assessed standard errors of all variables by decile and the relationship between death rates and socio-demographic variables with Pearson's correlations and linear regression by decile and for all constituencies combined. Standard errors in death rates and most socio-demographic variables were greatest for the most deprived decile. Death rates among all constituencies were positively correlated with Carstairs' score and indicators, density and BME, but for the most deprived decile, there was no association with Carstairs and a negative correlation with overcrowding, density and BME. For the most deprived decile multivariate models containing population density, BME and change had substantially higher R(2). Understanding variations in death rates between deprived areas requires greater consideration of their socio-demographic diversity including their population density, ethnicity and migration.

The Improved Hydrological Gravity Model for Moxa Observatory, Germany

NASA Astrophysics Data System (ADS)

Weise, A.; Jahr, Th.

2017-04-01

The gravity variations observed by the superconducting gravimeter (SG) CD-034 at Moxa Geodynamic Observatory/Germany were compared with the GRACE results some years ago. The combination of a local hydrological model of a catchment area with a 3D-gravimetric model had been applied successfully for correcting the SG record of Moxa which is especially necessary due to the strong topography nearest to the SG location. Now, the models have been corrected and improved considerably by inserting several details in the very near surrounding. Mainly these are: the observatory building is inserted with the roof covered by a soil layer above the gravity sensor where humidity is varying, snow is placed on top of the roof and on topography (steep slope), and ground water is taken into account, additionally. The result is that the comparison of the corrected gravity residuals with gravity variations of the satellite mission GRACE, now using RL5 data, shows higher agreement, not only in amplitude but also the formerly apparent phase shift is obviously not realistic. The agreement between terrestrial gravity variations (SG) and the GRACE data is improved considerably which is discussed widely.

The Improved Hydrological Gravity Model for Moxa Observatory, Germany

NASA Astrophysics Data System (ADS)

Weise, A.; Jahr, Th.

2018-05-01

The gravity variations observed by the superconducting gravimeter (SG) CD-034 at Moxa Geodynamic Observatory/Germany were compared with the GRACE results some years ago. The combination of a local hydrological model of a catchment area with a 3D-gravimetric model had been applied successfully for correcting the SG record of Moxa which is especially necessary due to the strong topography nearest to the SG location. Now, the models have been corrected and improved considerably by inserting several details in the very near surrounding. Mainly these are: the observatory building is inserted with the roof covered by a soil layer above the gravity sensor where humidity is varying, snow is placed on top of the roof and on topography (steep slope), and ground water is taken into account, additionally. The result is that the comparison of the corrected gravity residuals with gravity variations of the satellite mission GRACE, now using RL5 data, shows higher agreement, not only in amplitude but also the formerly apparent phase shift is obviously not realistic. The agreement between terrestrial gravity variations (SG) and the GRACE data is improved considerably which is discussed widely.

Interannual drought index variations in Central Europe related to large-scale atmospheric circulation

NASA Astrophysics Data System (ADS)

Beck, Christoph; Philipp, Andreas; Jacobeit, Jucundus

2014-05-01

This contribution investigates the relationship between large-scale atmospheric circulation and interannual variations of the standardized precipitation index (SPI) in central Europe. To this end occurrence frequencies of circulation types (CT) derived from a variety of circulation type classifications (CTC) applied to daily sea level pressure (SLP) data and mean circulation indices of vorticity (V), zonality (Z) and meridionality (M) have been utilized as predictors within multiple regression models (MRM) for the estimation of gridded 3-month SPI values over central Europe for the period 1950 to 2010. CTC based MRMs used in the analyses comprise variants concerning the basic method for CT classification, the number of CTs, the size and location of the spatial domain used for CTCs and the exclusive use of CT frequencies or the combined use of CT frequencies and mean circulation indices as predictors. Adequate MRM predictor combinations have been identified by applying stepwise multiple regression analyses within a resampling framework. The performance (robustness) of the resulting MRMs has been quantified based on a leave-one out cross-validation procedure applying several skill scores. Furthermore the relative importance of individual predictors has been estimated for each MRM. From these analyses it can be stated that i.) the consideration of vorticity characteristics within CTCs, ii.) a relatively small size of the spatial domain to which CTCs are applied and iii.) the inclusion of mean circulation indices appear to improve model skill. However model skill exhibits distinct variations between seasons and regions. Whereas promising skill can be stated for the western and northwestern parts of the central European domain only unsatisfactorily skill is reached in the more continental regions and particularly during summer. Thus it can be concluded that the here presented approaches feature the potential for the downscaling of central European drought index variations from large-scale circulation at least for some regions. Further improvements of CTC based approaches may be expected from the optimization of CTCs for explaining the SPI e.g. via the inclusion of additional variables into the classification procedure.

Interannual drought index variations in Central Europe related to the large-scale atmospheric circulation—application and evaluation of statistical downscaling approaches based on circulation type classifications

NASA Astrophysics Data System (ADS)

Beck, Christoph; Philipp, Andreas; Jacobeit, Jucundus

2015-08-01

This contribution investigates the relationship between the large-scale atmospheric circulation and interannual variations of the standardized precipitation index (SPI) in Central Europe. To this end, circulation types (CT) have been derived from a variety of circulation type classifications (CTC) applied to daily sea level pressure (SLP) data and mean circulation indices of vorticity ( V), zonality ( Z) and meridionality ( M) have been calculated. Occurrence frequencies of CTs and circulation indices have been utilized as predictors within multiple regression models (MRM) for the estimation of gridded 3-month SPI values over Central Europe, for the period 1950 to 2010. CTC-based MRMs used in the analyses comprise variants concerning the basic method for CT classification, the number of CTs, the size and location of the spatial domain used for CTCs and the exclusive use of CT frequencies or the combined use of CT frequencies and mean circulation indices as predictors. Adequate MRM predictor combinations have been identified by applying stepwise multiple regression analyses within a resampling framework. The performance (robustness) of the resulting MRMs has been quantified based on a leave-one-out cross-validation procedure applying several skill scores. Furthermore, the relative importance of individual predictors has been estimated for each MRM. From these analyses, it can be stated that model skill is improved by (i) the consideration of vorticity characteristics within CTCs, (ii) a relatively small size of the spatial domain to which CTCs are applied and (iii) the inclusion of mean circulation indices. However, model skill exhibits distinct variations between seasons and regions. Whereas promising skill can be stated for the western and northwestern parts of the Central European domain, only unsatisfactory skill is reached in the more continental regions and particularly during summer. Thus, it can be concluded that the presented approaches feature the potential for the downscaling of Central European drought index variations from the large-scale circulation, at least for some regions. Further improvements of CTC-based approaches may be expected from the optimization of CTCs for explaining the SPI, e.g. via the inclusion of additional variables in the classification procedure.

[Sediment transport characteristics at different erosion stages for non-hardened roads of the Shenfu Coalfield, west China].

PubMed

Guo, Ming-ming; Wang, Wen-long; Li, Jian-ming; Huang, Peng-fei; Zhu, Bao-cai; Wang, Zhen; Luo, Ting

2015-02-01

Non-hardened roads formed in the production of the Shenfu Coalfield have a unique condition of underlying surface. The road surface is composed of a regolith layer with a certain thickness resulted from long-term rolling and thus, is characterized by weakened anti-scourabilty and anti-erodibility. In contrast, soil layer below the regolith has a higher bulk density and anti-erodibility. The processes of soil erosion on the non-hardened roads exhibit some differences under rainfall condition. The process of sediment transport and the relationship between sediment transport rate and erosion factors at different erosion stages were studied on non-hardened roads with slope degrees ranging from 3° to 12° (3°, 6°, 9°, 12°) by a field experiment under artificial rainfall. Results showed that the first peak of sediment transport on the regolith surface was observed at the sheet erosion stage. Sheet erosion occurred only at 3° slope degree, with an average variation coefficient of 0.07 for sediment transport rate. Rills in every testing began to develop at slope degrees of 6° to 12° about 15 min after runoff initiation. At the sheet erosion stage, the process of sediment transport fluctuated considerably at rainfall intensities of > 1.5 mm · min(-1), but the differences in its variation were little at the three slope degrees, with average variation coefficients of 0.20, 0.19 and 0.16, respectively. Rainfall intensity had a more significant impact on sediment transport rate than slope degree. The process of sediment transport at the rill erosion stage fluctuated, but the fluctuation was obviously smaller than that at the sheet erosion stage, with average variation coefficients of 0.05, 0.09 and 0.10 at the three slope degrees. Many wide and shallow rills evolved at the rill erosion stage. The sediment transport rate could be well predicted by a power function of rainfall intensity and slope degree at the sheet and rill erosion stages. The stable sediment transport rate for all the tests was linearly related to runoff rate and sediment concentration.

Electrochemical kinetics and dimensional considerations, at the nanoscale

NASA Astrophysics Data System (ADS)

Yamada, H.; Bandaru, P. R.

2016-06-01

It is shown that the consideration of the density of states variation in nanoscale electrochemical systems yields modulations in the rate constant and concomitant electrical currents. The proposed models extend the utility of Marcus-Hush-Chidsey (MHC) kinetics to a larger class of materials and could be used as a test of dimensional character. The implications of the study are of much significance to an understanding and modulation of charge transfer nanostructured electrodes.

Understanding the organization of the amphibian egg cytoplasm - Gravitational force as a probe

NASA Technical Reports Server (NTRS)

Neff, Anton W.; Malacinski, George M.; Yokota, Hiroki; Wakahara, Masami

1992-01-01

A combination of hypergravity (centrifugation) and hypogravity (clinostat) studies have been carried out on amphibian (frog, Xenopus) eggs. The results reveal that the twinning caused by centrifugation exhibits substantial spawning to spawning variation. That variation can be attributed to the apparent viscosity of the egg's internal cytoplasm. Simulated hypogravity results in a relocation of the egg's third (horizontal) cleavage furrow, toward the equator. Substantial egg-to-egg variation is also observed in this 'cleavage effect'. For interpreting spaceflight data and for using G-forces as probes for understanding the egg's architecture the egg variation documented herein should be considered.

WEATHER ON OTHER WORLDS. III. A SURVEY FOR T DWARFS WITH HIGH-AMPLITUDE OPTICAL VARIABILITY

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

Heinze, Aren N.; Metchev, Stanimir; Kellogg, Kendra, E-mail: aren.heinze@stonybrook.edu, E-mail: smetchev@uwo.ca

2015-03-10

We have monitored 12 T dwarfs with the Kitt Peak 2.1 m telescope using an F814W filter (0.7-0.95 μm) to place in context the remarkable 10%-20% variability exhibited by the nearby T dwarf Luhman 16B in this wavelength regime. The motivation was the poorly known red optical behavior of T dwarfs, which have been monitored almost exclusively at infrared wavelengths, where variability amplitudes greater than 10% have been found to be very rare. We detect highly significant variability in two T dwarfs. The T2.5 dwarf 2MASS 13243559+6358284 shows consistent ∼17% variability on two consecutive nights. The T2 dwarf 2MASS J16291840+0335371 exhibits ∼10% variability thatmore » may evolve from night to night, similarly to Luhman 16B. Both objects were previously known to be variable in the infrared, but with considerably lower amplitudes. We also find evidence for variability in the T6 dwarf J162414.37+002915.6, but since it has lower significance, we conservatively refrain from claiming this object as a variable. We explore and rule out various telluric effects, demonstrating that the variations we detect are astrophysically real. We suggest that high-amplitude photometric variability for T dwarfs is likely more common in the red optical than at longer wavelengths. The two new members of the growing class of high-amplitude variable T dwarfs offer excellent prospects for further study of cloud structures and their evolution.« less

Comparative secretome analysis of four isogenic Bacillus clausii probiotic strains

PubMed Central

2013-01-01

Background The spore-bearing alkaliphilic Bacillus species constitute a large, heterogeneous group of microorganisms, important for their ability to produce enzymes, antibodies and metabolites of potential medical use. Some Bacillus species are currently being used for manufacturing probiotic products consisting of bacterial spores, exhibiting specific features (colonization, immune-stimulation and antimicrobial activity) that can account for their claimed probiotic properties. In the present work a comparative proteomic study was performed aimed at characterizing the secretome of four closely related isogenic O/C, SIN, N/R and T B. clausii strains, already marketed in a pharmaceutical mixture as probiotics. Results Proteomic analyses revealed a high degree of concordance among the four secretomes, although some proteins exhibited considerable variations in their expression level in the four strains. Among these, some proteins with documented activity in the interaction with host cells were identified, such as the glycolytic enzyme enolase, with a putative plasminogen-binding activity, GroEL, a molecular chaperone shown to be able to bind to mucin, and flagellin protein, a structural flagella protein and a putative immunomodulation agent. Conclusion This study shows, for the first time, differences in the secretome of the OC, SIN, NR and T B. clausii strains. These differences indicate that specific secretome features characterize each of the four strains despite their genotypic similarity. This could confer to the B. clausii strains specific probiotic functions associated with the differentially expressed proteins and indicate that they can cooperate as probiotics as the secretome components of each strain could contribute to the overall activity of a mixed probiotic preparation. PMID:23816335

Unusual twig "twistiness" in pawpaw (Asimina triloba) provides biomechanical protection for distal foliage in high winds.

PubMed

Goodrich, Katherine R; Ortiz, Luis A; Coughlin, David J

2016-11-01

Deciduous woody species invest considerable resources in the growth of new foliage and distal stems. This new growth is at risk for mechanical damage from high winds and storms. Pawpaw has large leaves borne distally on thin twigs. Following a storm, pawpaw branches sometimes exhibit a persistent "flipped" orientation, slowly returning upright over 24 h. We investigated biomechanical properties of pawpaw twigs, comparing them to co-occurring species with similarly high leaf areas and loads, which do not exhibit this "flipping". Our goal was to determine biomechanical and structural properties in these species and how variation in form might relate to functional differences. We measured flexural stiffness, torsional stiffness, and viscoelastic creep in pawpaw and co-occurring trees Liriodendron tulipifera and Carya cordiformis. We also recorded twig/foliage reconfiguration in high winds. We stained thin cross sections of distal twigs and recorded images using fluorescent light microscopy. Flexural and torsional stiffness increased with twig radius in pawpaw and tulip tree, although torsional stiffness increased more slowly in pawpaw. Pawpaw had a high ratio of flexural to torsional stiffness (EI/GJ) across a range of twig radii and significant viscoelastic creep compared with the other species. Biomechanical data showed that pawpaw twigs were "twistier" than the comparison species, which were shown previously to alleviate drag-induced damage by reorienting petioles and leaves. Pawpaw has an unusual strategy of low torsional stiffness in twigs, allowing for reorientation of the entire distal appendage, likely minimizing drag-induced damage in storms. © 2016 Botanical Society of America.

On the prediction of the Free Core Nutation

NASA Astrophysics Data System (ADS)

Belda Palazón, Santiago; Ferrándiz, José M.; Heinkelmann, Robert; Nilsson, Tobias; Schuh, Harald; Modiri, Sadegh

2017-04-01

Consideration of the Free Core Nutation (FCN) model is obliged for improved modelling of the Celestial Pole Offsets (CPO), since it is the major source of inaccuracy or unexplained time variability with respect to the current IAU2000 nutation theory. FCN is excited from various geophysical sources and thus it cannot be known until it is inferred from observations. However, given that the variations of the FCN signal are slow and seldom abrupt, we examine whether the availability of new FCN empirical models (i.e., Malkin 2007; Krásná et al. 2013; Belda et al. 2016) can be exploited to make reasonably accurate predictions of the FCN signal before observing it. In this work we study CPO predictions for the FCN model provided by Belda et al. 2016, in which the amplitude coefficients were estimated by using a sliding window with a width of 400 days and with a minimal displacement between the subsequent fits (one-day step). Our results exhibit two significant features: (1) the prediction of the FCN signal can be done on the basis of its prior amplitudes with a mean error of about 30 microarcseconds per year, with an apparent linear trend; and (2) the Weighted Root Mean Square (wrms) of the differences between the CPO produced by the IERS (International Earth Rotation and Reference Systems Service) and our predicted FCN exhibit an exponential slow-growing pattern, with a wmrs close to 120 microarcseconds along several months. Therefore a substantial improvement with respect to the CPO operational predictions of the IERS Rapid Service/Prediction Centre can be achieved.

A new model-free index of dynamic cerebral blood flow autoregulation.

PubMed

Chacón, Max; Jara, José Luis; Panerai, Ronney B

2014-01-01

The classic dynamic autoregulatory index (ARI), proposed by Aaslid and Tiecks, is one of the most widely used methods to assess the efficiency of dynamic cerebral autoregulation. Although this index is often used in clinical research and is also included in some commercial equipment, it exhibits considerable intra-subject variability, and has the tendency to produce false positive results in clinical applications. An alternative index of dynamic cerebral autoregulation is proposed, which overcomes most of the limitations of the classic method and also has the advantage of being model-free. This new index uses two parameters that are obtained directly from the response signal of the cerebral blood flow velocity to a transient decrease in arterial blood pressure provoked by the sudden release of bilateral thigh cuffs, and a third parameter measuring the difference in slope of this response and the change in arterial blood pressure achieved. With the values of these parameters, a corresponding classic autoregulatory index value could be calculated by using a linear regression model built from theoretical curves generated with the Aaslid-Tiecks model. In 16 healthy subjects who underwent repeated thigh-cuff manoeuvres, the model-free approach exhibited significantly lower intra-subject variability, as measured by the unbiased coefficient of variation, than the classic autoregulatory index (p = 0.032) and the Rate of Return (p<0.001), another measure of cerebral autoregulation used for this type of systemic pressure stimulus, from 39.23%±41.91% and 55.31%±31.27%, respectively, to 15.98%±7.75%.

A New Model-Free Index of Dynamic Cerebral Blood Flow Autoregulation

PubMed Central

Chacón, Max; Jara, José Luis; Panerai, Ronney B.

2014-01-01

The classic dynamic autoregulatory index (ARI), proposed by Aaslid and Tiecks, is one of the most widely used methods to assess the efficiency of dynamic cerebral autoregulation. Although this index is often used in clinical research and is also included in some commercial equipment, it exhibits considerable intra-subject variability, and has the tendency to produce false positive results in clinical applications. An alternative index of dynamic cerebral autoregulation is proposed, which overcomes most of the limitations of the classic method and also has the advantage of being model-free. This new index uses two parameters that are obtained directly from the response signal of the cerebral blood flow velocity to a transient decrease in arterial blood pressure provoked by the sudden release of bilateral thigh cuffs, and a third parameter measuring the difference in slope of this response and the change in arterial blood pressure achieved. With the values of these parameters, a corresponding classic autoregulatory index value could be calculated by using a linear regression model built from theoretical curves generated with the Aaslid-Tiecks model. In 16 healthy subjects who underwent repeated thigh-cuff manoeuvres, the model-free approach exhibited significantly lower intra-subject variability, as measured by the unbiased coefficient of variation, than the classic autoregulatory index (p = 0.032) and the Rate of Return (p<0.001), another measure of cerebral autoregulation used for this type of systemic pressure stimulus, from 39.23%±41.91% and 55.31%±31.27%, respectively, to 15.98%±7.75%. PMID:25313519

Fabrication and characterization of crushed titanium-beryllium intermetallic compounds

NASA Astrophysics Data System (ADS)

Kim, Jae-Hwan; Nakamichi, Masaru

2018-01-01

To develop a technique for the mass production of beryllide pebbles, a crushing method for the granulation of beryllides was used in this study. Two types of crushed Be12Ti pebbles were prepared using mortar-ground (MG) and planetary-ball-milled (PM) powders. A granulation yield of approximately 50 wt.% with sizes in the range of 0.85-1.18 mm was achieved. Scanning electron microscopy (SEM) images revealed that the MG pebbles exhibited larger porosity because the larger size of the powder resulted in lower density with higher porosity. However, the considerably larger fraction of fine pores in the PM pebbles resulted in an increased Brunauer-Emmett-Teller (BET) specific surface area, as clearly demonstrated by high-magnification SEM images. To evaluate the reactivity with water vapor, the weight gain and H2 generation rate were also investigated. The results suggested that the PM pebbles exhibited notably lower reactivity, weight gain, and H2 generation rate, which may be due to the dramatically decreased BET specific surface. The fine pores were filled with stable oxides followed by a significant decrease of the surface area during oxidation. Optimization was performed to improve the circularity of the crushed pebbles. Grinding tests using planetary milling without balls for different times clearly demonstrated that the circularity improved (with an estimated value of 0.8) by cutting and polishing the sharp edges; however, long-duration milling for 99 h resulted in attachment of the polished powders to the pebble surface, leading to surface color variation of the crushed pebbles.

Secular Orbit and Spin Variations of Asteroid (16) Psyche

NASA Astrophysics Data System (ADS)

Bills, B. G.; Park, R. S.; Scott, B.

2016-12-01

The obliquity, or angular separation between spin and orbit poles, of asteroid (16) Psyche is currently 95 degrees. We are interested in knowing how much that angular separation varies, on time scales of 104 to 106 years. To answer that question, we have done several related analyses. On short time scales, the orbital element variations of Psyche are dominated by perturbations from Jupiter. Jupiter's dominance has two basic causes: first is the large mass and relatively close position of Jupiter, and second is a 19:8 mean motion resonance. Jupiter completes 8 orbits in 94.9009 years, while Psyche takes 94.9107 years to complete 19 orbits. As a result of this, all of the orbital elements of Psyche exhibit significant periodic variations, with a 94.9 year period dominating. There are also significant variations at the synodic period, which is 8.628 years, or 1/11 of the resonant period. Over a 1000 year time span, centered on the present, the eccentricity varies from 0.133 to 0.140, and the inclination varies from 2.961 to 3.229 degrees. On longer time scales, the orbital elements of Psyche vary considerably more than that, due to secular perturbations from the planets. The secular variations are modeled as the response of interacting mass rings, rather than point masses. Again, Jupiter is the main perturbing influence on Psyche. The eccentricity and inclination both oscillate, with dominant periods of 18.667 kyr. The range of values seen over a million year time span, is 0.057 to 0.147 for eccentricity, and 0.384 to 4.777 degrees for inclination. Using a recent shape model, and assumption of uniform density, to constrain relevant moments of inertia, we estimate the spin pole precession rate parameter to be 8.53 arcsec/year. The current spin pole is at ecliptic {lon, lat} = { 32, -7} deg, whereas the orbit pole is at {lon, lat} = {60.47, 86.91} deg. The current obliquity is thus 94.3 degree. Using nominal values of the input parameters, the recovered spin pole trajectory is such that, over a million year time span, centered on the present, the minimum and maximum values of obliquity are 92.36 and 98.56 deg. The obliquity oscillates with dominant periods of 18.45 and 48.40 kyr.

Occlusal status and prevalence of occlusal malocclusion traits among 9-year-old schoolchildren.

PubMed

Lux, Christopher J; Dücker, Britta; Pritsch, Maria; Komposch, Gerda; Niekusch, Uwe

2009-06-01

The aim of this study was to provide detailed information concerning clinically relevant occlusal traits and the prevalence of occlusal anomalies in an orthodontically relevant period of dental development. Four hundred and ninety-four German schoolchildren (237 males and 257 females), median age 9 years, were orthodontically examined. Overjet and overbite were measured to the nearest 0.5 mm, and sagittal molar relationships were registered clinically to the nearest quarter unit. In addition, crossbites, scissor bites, and midline displacements were evaluated. Descriptive statistics was complemented by testing gender differences and differences between groups with Class I and Class II anomalies (Mann-Whitney U-test) as well as a statistical evaluation of differences between the three dental stages (Kruskal-Wallis test). Overjet exhibited an extreme range between -2 and 12 mm (median values 3-3.5 mm). An increased overjet was more prevalent than a reduced or reverse overjet, and a severely increased overjet greater than 6 mm was a common finding affecting around 5-10 per cent of the children. Similarly, overbite showed considerable variations of between -1 and 9 mm (medians 3-3.5 mm) and males exhibited a significantly larger overbite than females. In Class II malocclusion subjects, overbite was significantly enlarged (on average between 0.5 and 1 mm) when compared with those with a Class I malocclusion. Traumatic contact of the gingiva affected every 14th child. A Class II molar relationship of three-quarter units or more was a frequent finding affecting more than one child in five. In addition, at 9 years of age, 3 per cent of the children exhibited a Class III molar relationship of at least a half unit. The wide range of orthodontically relevant occlusal traits found in the present study underlines the need for orthodontic screening at 9 years of age (or earlier).

Associations between dopamine D4 receptor gene variation with both infidelity and sexual promiscuity.

PubMed

Garcia, Justin R; MacKillop, James; Aller, Edward L; Merriwether, Ann M; Wilson, David Sloan; Lum, J Koji

2010-11-30

Human sexual behavior is highly variable both within and between populations. While sex-related characteristics and sexual behavior are central to evolutionary theory (sexual selection), little is known about the genetic bases of individual variation in sexual behavior. The variable number tandem repeats (VNTR) polymorphism in exon III of the human dopamine D4 receptor gene (DRD4) has been correlated with an array of behavioral phenotypes and may be predicatively responsible for variation in motivating some sexual behaviors, particularly promiscuity and infidelity. We administered an anonymous survey on personal history of sexual behavior and intimate relationships to 181 young adults. We also collected buccal wash samples and genotyped the DRD4 VNTR. Here we show that individuals with at least one 7-repeat allele (7R+) report a greater categorical rate of promiscuous sexual behavior (i.e., having ever had a "one-night stand") and report a more than 50% increase in instances of sexual infidelity. DRD4 VNTR genotype varies considerably within and among populations and has been subject to relatively recent, local selective pressures. Individual differences in sexual behavior are likely partially mediated by individual genetic variation in genes coding for motivation and reward in the brain. Conceptualizing these findings in terms of r/K selection theory suggests a mechanism for selective pressure for and against the 7R+ genotype that may explain the considerable global allelic variation for this polymorphism.

Associations between Dopamine D4 Receptor Gene Variation with Both Infidelity and Sexual Promiscuity

PubMed Central

Garcia, Justin R.; MacKillop, James; Aller, Edward L.; Merriwether, Ann M.; Wilson, David Sloan; Lum, J. Koji

2010-01-01

Background Human sexual behavior is highly variable both within and between populations. While sex-related characteristics and sexual behavior are central to evolutionary theory (sexual selection), little is known about the genetic bases of individual variation in sexual behavior. The variable number tandem repeats (VNTR) polymorphism in exon III of the human dopamine D4 receptor gene (DRD4) has been correlated with an array of behavioral phenotypes and may be predicatively responsible for variation in motivating some sexual behaviors, particularly promiscuity and infidelity. Methodology/Principal Findings We administered an anonymous survey on personal history of sexual behavior and intimate relationships to 181 young adults. We also collected buccal wash samples and genotyped the DRD4 VNTR. Here we show that individuals with at least one 7-repeat allele (7R+) report a greater categorical rate of promiscuous sexual behavior (i.e., having ever had a “one-night stand”) and report a more than 50% increase in instances of sexual infidelity. Conclusions/Significance DRD4 VNTR genotype varies considerably within and among populations and has been subject to relatively recent, local selective pressures. Individual differences in sexual behavior are likely partially mediated by individual genetic variation in genes coding for motivation and reward in the brain. Conceptualizing these findings in terms of r/K selection theory suggests a mechanism for selective pressure for and against the 7R+ genotype that may explain the considerable global allelic variation for this polymorphism. PMID:21152404

Sizing ocean giants: patterns of intraspecific size variation in marine megafauna

PubMed Central

Balk, Meghan A.; Benfield, Mark C.; Branch, Trevor A.; Chen, Catherine; Cosgrove, James; Dove, Alistair D.M.; Gaskins, Lindsay C.; Helm, Rebecca R.; Hochberg, Frederick G.; Lee, Frank B.; Marshall, Andrea; McMurray, Steven E.; Schanche, Caroline; Stone, Shane N.; Thaler, Andrew D.

2015-01-01

What are the greatest sizes that the largest marine megafauna obtain? This is a simple question with a difficult and complex answer. Many of the largest-sized species occur in the world’s oceans. For many of these, rarity, remoteness, and quite simply the logistics of measuring these giants has made obtaining accurate size measurements difficult. Inaccurate reports of maximum sizes run rampant through the scientific literature and popular media. Moreover, how intraspecific variation in the body sizes of these animals relates to sex, population structure, the environment, and interactions with humans remains underappreciated. Here, we review and analyze body size for 25 ocean giants ranging across the animal kingdom. For each taxon we document body size for the largest known marine species of several clades. We also analyze intraspecific variation and identify the largest known individuals for each species. Where data allows, we analyze spatial and temporal intraspecific size variation. We also provide allometric scaling equations between different size measurements as resources to other researchers. In some cases, the lack of data prevents us from fully examining these topics and instead we specifically highlight these deficiencies and the barriers that exist for data collection. Overall, we found considerable variability in intraspecific size distributions from strongly left- to strongly right-skewed. We provide several allometric equations that allow for estimation of total lengths and weights from more easily obtained measurements. In several cases, we also quantify considerable geographic variation and decreases in size likely attributed to humans. PMID:25649000

Variational method of determining effective moduli of polycrystals: (A) hexagonal symmetry, (B) trigonal symmetry

USGS Publications Warehouse

Peselnick, L.; Meister, R.

1965-01-01

Variational principles of anisotropic elasticity have been applied to aggregates of randomly oriented pure-phase polycrystals having hexagonal symmetry and trigonal symmetry. The bounds of the effective elastic moduli obtained in this way show a considerable improvement over the bounds obtained by means of the Voigt and Reuss assumptions. The Hill average is found to be in most cases a good approximation when compared to the bounds found from the variational method. The new bounds reduce in their limits to the Voigt and Reuss values. ?? 1965 The American Institute of Physics.

Hydrotherapy in burn care: a survey of hydrotherapy practices in the UK and Ireland and literature review.

PubMed

Langschmidt, Jenna; Caine, Paul L; Wearn, Christopher M; Bamford, Amy; Wilson, Yvonne T; Moiemen, Naiem S

2014-08-01

Hydrotherapy is widely used in burns management however there are risks associated with its use, in particular cross-infection. Data regarding indications and techniques in common use is deficient. This study aimed to investigate hydrotherapy practices in the UK and Ireland. A survey of the hydrotherapy practice of major burn care providers was performed by e mail and where necessary, follow up telephone contact. The survey included 28 burn care providers. 27 reported using hydrotherapy. Only 11 (41%) had defined indication criteria with 4 (15%) implementing a specific protocol. Variations in hydrotherapy practice were seen. Hydrotherapy is used nationwide, however considerable variation in practice exists. One area worthy of further consideration is the need for appropriate standards of infection control. Copyright © 2013 Elsevier Ltd and ISBI. All rights reserved.

Genetic variation for pseudo-self-compatibility in self-incompatible populations of Leavenworthia alabamica (Brassicaceae).

PubMed

Baldwin, Sarah J; Schoen, Daniel J

2017-01-01

Self-incompatibility (SI) promotes outcrossing, but transitions to self-compatibility (SC) are frequent. Population genetic theory describing the breakdown of SI to SC suggests that, under most conditions, populations should be composed of either SI or SC individuals. Under a narrow range of conditions, theory suggests that SI may persist alongside reduced expression of SI (pseudo-SI, PSI) in mixed-mating populations. We studied genetic variation for PSI segregating in four SI populations of Leavenworthia alabamica by measurement of the heritability of pollen tube number after self-pollination. We tested for the role of the S-locus in this variation by sequencing seven S-alleles from plants with high pseudo-SC (PSC) and testing for the co-segregation of these alleles with PSC. We found a continuous distribution of PSC in all populations and 90% of plants exhibited PSC. The heritability ranged from 0.39 to 0.57. All seven S-alleles from plants with high PSC exhibited trans-specific polymorphism, and no stop codons were observed within the c. 600-bp region sequenced. One of these S-alleles was directly associated with the inheritance of PSC. We conclude that heritable variation in PSC is largely a result of genetic variation in the signaling cascade downstream of the S-locus reaction, together with the presence of one leaky S-allele. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

High-speed spectral infrared imaging of spark ignition engine combustion. (Reannouncement with new availability information)

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

McComiskey, T.; Jiang, H.; Qian, Y.

1993-03-05

In-cylinder flame propagation and its impact on thermal characteristics of the combustion chamber were studied by using a new high-speed spectral infrared imaging system. In this work, successive spectral IR images of combustion chamber events were captured while varying several parameters, including fuel/air, spark timing, speed, and warming-up period. Some investigation of cyclic variation, knock, and high-temperature components during the non-combustion period was also conducted. It was found that the spectral images obtained in both short and long wavelength bands exhibited unique pieces of in-cylinder information, i.e., (qualitative) distributions of temperature and combustion products, respectively. During the combustion period, themore » temperature of early-formed combustion products continued to increase while the flame front temperature, e.g. near the end gas zone, remained relatively low. The exhaust valve emitted strong radiation starting from the early stage of the combustion period. The spark plug emitted the strongest radiation during the non-combustion period. Considerable cyclic variation in growth of the flame front and completion of the reaction was observable. The radiation from both spectral bands became stronger as the engine warm-up period in While operating the engine with the addition of n-heptane in the intake to produce knock, we captured spectral IR images of the end gas right before it was abruptly consumed. The combustion products that were formed in the end-gas volume upon knock, showed no evidence of higher temperature than other zones in the combustion chamber.... Spectral infrared imaging, High-speed, Digital data, Instantaneous distribution, Spark ignition combustion.« less

Loss of nutrients from terrestrial ecosystems to streams and the atmosphere following land use change in Amazonia

NASA Astrophysics Data System (ADS)

Davidson, Eric A.; Neill, Christopher; Krusche, Alex V.; Ballester, Victoria V. R.; Markewitz, Daniel; Figueiredo, Ricardo de O.

Rates of deforestation in the Amazon region have been accelerating, but the quantity and timing of nutrient losses from forested and deforested ecosystems are poorly understood. This paper investigates the broad variation in soil properties of the Amazon Basin as they influence transfers of plant nutrients from the terrestrial biosphere to the atmosphere and the aquatic biosphere. The dominant lowland soils are highly weathered Oxisols and Ultisols, but significant areas of Alfisols also exist, resulting in a wide range of weatherable primary minerals. Despite this considerable variation among Amazonian soils, a common feature in most mature lowland Amazonian forests is a conservative P cycle and excess N availability. In cattle pastures and secondary forests, however, low rates of internal terrestrial N cycling, low N export to streams, and low gaseous N emissions from soils are common, due to significant previous losses of N through repeated fire. Export of P to streams may increase or remain nearly undetectable after forest-to-pasture conversion, depending on soil type. Oxisols exhibit very low P export, whereas increased P export to pasture streams has been observed in Ultisols of western Amazonia. Calcium is mostly retained in terrestrial ecosystems following deforestation, although increased inputs to streams can be detected when background fluxes are naturally low. Because soil mineralogy and soil texture are both variable and important, the effects of land-use change on nutrient export to aquatic ecosystems and to the atmosphere must be understood within the context of varying soil properties across the Amazon Basin.

Quantifying Intrinsic and Extrinsic Variability in Stochastic Gene Expression Models

PubMed Central

Singh, Abhyudai; Soltani, Mohammad

2013-01-01

Genetically identical cell populations exhibit considerable intercellular variation in the level of a given protein or mRNA. Both intrinsic and extrinsic sources of noise drive this variability in gene expression. More specifically, extrinsic noise is the expression variability that arises from cell-to-cell differences in cell-specific factors such as enzyme levels, cell size and cell cycle stage. In contrast, intrinsic noise is the expression variability that is not accounted for by extrinsic noise, and typically arises from the inherent stochastic nature of biochemical processes. Two-color reporter experiments are employed to decompose expression variability into its intrinsic and extrinsic noise components. Analytical formulas for intrinsic and extrinsic noise are derived for a class of stochastic gene expression models, where variations in cell-specific factors cause fluctuations in model parameters, in particular, transcription and/or translation rate fluctuations. Assuming mRNA production occurs in random bursts, transcription rate is represented by either the burst frequency (how often the bursts occur) or the burst size (number of mRNAs produced in each burst). Our analysis shows that fluctuations in the transcription burst frequency enhance extrinsic noise but do not affect the intrinsic noise. On the contrary, fluctuations in the transcription burst size or mRNA translation rate dramatically increase both intrinsic and extrinsic noise components. Interestingly, simultaneous fluctuations in transcription and translation rates arising from randomness in ATP abundance can decrease intrinsic noise measured in a two-color reporter assay. Finally, we discuss how these formulas can be combined with single-cell gene expression data from two-color reporter experiments for estimating model parameters. PMID:24391934

Quantifying intrinsic and extrinsic variability in stochastic gene expression models.

PubMed

Singh, Abhyudai; Soltani, Mohammad

2013-01-01

Genetically identical cell populations exhibit considerable intercellular variation in the level of a given protein or mRNA. Both intrinsic and extrinsic sources of noise drive this variability in gene expression. More specifically, extrinsic noise is the expression variability that arises from cell-to-cell differences in cell-specific factors such as enzyme levels, cell size and cell cycle stage. In contrast, intrinsic noise is the expression variability that is not accounted for by extrinsic noise, and typically arises from the inherent stochastic nature of biochemical processes. Two-color reporter experiments are employed to decompose expression variability into its intrinsic and extrinsic noise components. Analytical formulas for intrinsic and extrinsic noise are derived for a class of stochastic gene expression models, where variations in cell-specific factors cause fluctuations in model parameters, in particular, transcription and/or translation rate fluctuations. Assuming mRNA production occurs in random bursts, transcription rate is represented by either the burst frequency (how often the bursts occur) or the burst size (number of mRNAs produced in each burst). Our analysis shows that fluctuations in the transcription burst frequency enhance extrinsic noise but do not affect the intrinsic noise. On the contrary, fluctuations in the transcription burst size or mRNA translation rate dramatically increase both intrinsic and extrinsic noise components. Interestingly, simultaneous fluctuations in transcription and translation rates arising from randomness in ATP abundance can decrease intrinsic noise measured in a two-color reporter assay. Finally, we discuss how these formulas can be combined with single-cell gene expression data from two-color reporter experiments for estimating model parameters.

Variations in pockmark composition at the Vestnesa Ridge: Insights from marine controlled source electromagnetic and seismic data

NASA Astrophysics Data System (ADS)

Goswami, Bedanta K.; Weitemeyer, Karen A.; Bünz, Stefan; Minshull, Timothy A.; Westbrook, Graham K.; Ker, Stephan; Sinha, Martin C.

2017-03-01

The Vestnesa Ridge marks the northern boundary of a known submarine gas hydrate province in the west Svalbard margin. Several seafloor pockmarks at the eastern segment of the ridge are sites of active methane venting. Until recently, seismic reflection data were the main tool for imaging beneath the ridge. Coincident controlled source electromagnetic (CSEM), high-resolution two-dimensional (2-D) airgun, sweep frequency SYSIF, and three-dimensional (3-D) p-cable seismic reflection data were acquired at the south-eastern part of the ridge between 2011 and 2013. The CSEM and seismic data contain profiles across and along the ridge, passing several active and inactive pockmarks. Joint interpretation of resistivity models obtained from CSEM and seismic reflection data provides new information regarding the fluid composition beneath the pockmarks. There is considerable variation in transverse resistance and seismic reflection characteristics of the gas hydrate stability zone (GHSZ) between the ridge flanks and chimneys beneath pockmarks. Layered seismic reflectors on the flanks are associated with around 300 Ωm2 transverse resistance, whereas the seismic reflectors within the chimneys exhibit amplitude blanking and chaotic patterns. The transverse resistance of the GHSZ within the chimneys vary between 400 and 1200 Ωm2. Variance attributes obtained from the 3-D p-cable data also highlight faults and chimneys, which coincide with the resistivity anomalies. Based on the joint data interpretation, widespread gas hydrate presence is likely at the ridge, with both hydrates and free gas contained within the faults and chimneys. However, at the active chimneys the effect of gas likely dominates the resistive anomalies.

Phenological indicators derived with CO2 flux, MODIS image and ground monitor at a temperate mixed forest and an alpine shrub

NASA Astrophysics Data System (ADS)

Zhang, Leiming; Cao, Peiyu; Li, Shenggong; Yu, Guirui; Zhang, Junhui; Li, Yingnian

2016-04-01

To accurately assess the change of phenology and its relationship with ecosystem gross primary productivity (GPP) is one of the key issues in context of global change study. In this study, an alpine shrubland meadow in Haibei (HBS) of Qinghai-Tibetan plateau and a broad-leaved Korean pine forest in Changbai Mountain (CBM) of Northeastern China were selected. Based on the long-term GPP from eddy flux measurements and the Normalized Difference Vegetation Index (NDVI) from remote sensed vegetation index, phenological indicators including the start of growing season (SOS), the end of growing season (EOS), and the growing season length (GSL) since 2003 were derived via multiple methods, and then the influences of phenology variation on GPP were explored. Compared with ground phenology observations of dominant plant species, both GPP- and NDVI-derived SOS and EOS exhibited a similar interannual trend. GPP-derived SOS was quite close to NDVI-derived SOS, but GPP-derived EOS differed significantly from NDVI-derived EOS, and thus leading to a significant difference between GPP- and NDVI-derived GSL. Relative to SOS, EOS presented larger differences between the extraction methods, indicating large uncertainties to accurately define EOS. In general, among the methods used, the threshold methods produced more satisfactory assessment on phenology change. This study highlights that how to harmonize with the flux measurements, remote sensing and ground monitoring are a big challenge that needs further consideration in phenology study, especially the accurate extraction of EOS. Key words: phenological variation, carbon flux, vegetation index, vegetation grwoth, interannual varibility

Towards evidence based strength training: a comparison of muscle forces during deadlifts, goodmornings and split squats.

PubMed

Schellenberg, Florian; Taylor, William R; Lorenzetti, Silvio

2017-01-01

To ensure an efficient and targeted adaptation with low injury risk during strength exercises, knowledge of the participant specific internal loading conditions is essential. The goal of this study was to calculate the lower limb muscles forces during the strength exercises deadlifts, goodmornings and splits squats by means of musculoskeletal simulation. 11 participants were assessed performing 10 different variations of split squats by varying the step length as well as the maximal frontal tibia angle, and 13 participants were measured performing deadlift and goodmorning exercises. Using individualised musculoskeletal models, forces of the Quadriceps ( four parts), Hamstrings (four parts) and m. gluteus maximus (three parts) were computed. Deadlifts resulted highest loading for the Quadriceps, especially for the vasti (18-34 N/kg), but not for the rectus femoris (8-10 N/kg), which exhibited its greatest loading during split squats (13-27 N/kg) in the rear limb. Hamstrings were loaded isometrically during goodmornings but dynamically during deadlifts. For the m. gluteus maximus , the highest loading was observed during split squats in the front limb (up to 25 N/kg), while deadlifts produced increasingly, large loading over large ranges of motion in hip and knee. Acting muscle forces vary between exercises, execution form and joint angle. For all examined muscles, deadlifts produced considerable loading over large ranges of motion, while split squats seem to be highly dependent upon exercise variation. This study provides key information to design strength-training programs with respect to loading conditions and ranges of motion of lower extremity muscles.

Variability of gastrointestinal transit in healthy women and men.

PubMed Central

Degen, L P; Phillips, S F

1996-01-01

BACKGROUND AND AIMS: Measurements of gastrointestinal transit are made in clinical and research gastroenterology, yet their intrinsic variability is not well characterised. In particular, an influence of hormones on transit has been proposed as the basis for gastrointestinal symptoms that vary with the menstrual cycle. Our aims were to quantify individual differences in transit during the menstrual cycle in healthy women and to compare these with the intrinsic variability in healthy men. METHODS: On two occasions, whole gut transit was assessed scintigraphically and colonic transit quantified by radio-opaque markers. Thirty two healthy volunteers (12 women, 20 men) were studied, women during the follicular and luteal phases, men twice within a similar four week period. Diets and exercise were standardised prior to and during both studies. RESULTS: Colonic transit was significantly faster in men, and postlag gastric emptying was also more rapid; other indices of regional transit were not different between the sexes. Total colonic transit time was equally well reflected by the scintigraphic and radio-opaque marker methods. Important intraindividual differences were noted in both sexes. The variances in our samples predicted an 80% chance of detecting (with 95% confidence) a mean effect of menstrual hormones on transit that was in the same range as the intrinsic variation in men. CONCLUSIONS: Colonic transit was faster in men than in women. Although group means in the two studies were almost identical, single assessments of transit in subjects sometimes exhibited considerable variability, implying broad biological variations. Given this intrinsic variability, the influence of menstrual hormones on gastrointestinal transit must be small and of doubtful clinical significance. PMID:8977347

Earth Rotation

NASA Technical Reports Server (NTRS)

Dickey, Jean O.

1995-01-01

The study of the Earth's rotation in space (encompassing Universal Time (UT1), length of day, polar motion, and the phenomena of precession and nutation) addresses the complex nature of Earth orientation changes, the mechanisms of excitation of these changes and their geophysical implications in a broad variety of areas. In the absence of internal sources of energy or interactions with astronomical objects, the Earth would move as a rigid body with its various parts (the crust, mantle, inner and outer cores, atmosphere and oceans) rotating together at a constant fixed rate. In reality, the world is considerably more complicated, as is schematically illustrated. The rotation rate of the Earth's crust is not constant, but exhibits complicated fluctuations in speed amounting to several parts in 10(exp 8) [corresponding to a variation of several milliseconds (ms) in the Length Of the Day (LOD) and about one part in 10(exp 6) in the orientation of the rotation axis relative to the solid Earth's axis of figure (polar motion). These changes occur over a broad spectrum of time scales, ranging from hours to centuries and longer, reflecting the fact that they are produced by a wide variety of geophysical and astronomical processes. Geodetic observations of Earth rotation changes thus provide insights into the geophysical processes illustrated, which are often difficult to obtain by other means. In addition, these measurements are required for engineering purposes. Theoretical studies of Earth rotation variations are based on the application of Euler's dynamical equations to the problem of finding the response of slightly deformable solid Earth to variety of surface and internal stresses.

Morphological, anatomical, and ultrastructural changes (visualized through scanning electron microscopy) induced in Triticum aestivum by Pb²⁺ treatment.

PubMed

Kaur, Gurpreet; Singh, Harminder Pal; Batish, Daizy Rani; Kohli, Ravinder Kumar

2014-11-01

Lead (Pb) causes severe damage to crops, ecosystems, and humans, and alters the physiology and biochemistry of various plant species. It is hypothesized that Pb-induced metabolic alterations could manifest as structural variations in the roots of plants. In light of this, the morphological, anatomical, and ultrastructural variations (through scanning electron microscopy, SEM) were studied in 4-day-old seedlings of Triticum aestivum grown under Pb stress (0, 8, 16, 40, and 80 mg Pb(2+) l(-1); mild to highly toxic). The toxic effect was more pronounced in radicle growth than on the plumule growth. The SEM of the root of T. aestivum depicted morphological alterations and surface ultrastructural changes. Compared to intact and uniform surface cells in the control roots, cells were irregular and desiccated in Pb(2+)-treated roots. In Pb(2+)-treated roots, the number of root hairs increased manifold, showing dense growth, and these were apparently longer. Apart from the deformity in surface morphology and anatomy of the roots in response to Pb(2+) toxicity, considerable anatomical alterations were also observed. Pb(2+)-treated root exhibited signs of injury in the form of cell distortion, particularly in the cortical cells. The endodermis and pericycle region showed loss of uniformity post Pb(2+) exposure (at 80 mg l(-1) Pb(2+)). The cells appeared to be squeezed with greater depositions observed all over the tissue. The study concludes that Pb(2+) treatment caused structural anomalies and induced anatomical and surface ultrastructural changes in T. aestivum.

Ionosphere of venus: first observations of day-night variations of the ion composition.

PubMed

Taylor, H A; Brinton, H C; Bauer, S J; Hartle, R E; Cloutier, P A; Daniell, R E; Donahue, T M

1979-07-06

The Bennett radio-frequency ion mass spectrometer on the Pioneer Venus orbiter is returning the first direct composition evidence of the processes responsible for the formation and maintenance of the nightside ionosphere. Early results from predusk through the nightside in the solar zenith angle range 63 degrees (dusk) to 120 degrees (dawn) reveal that, as on the dayside, the lower nightside ionosphere consists of F(1)and F(2) layers dominated by O(2)(+) and O(+), respectively. Also like the dayside, the nightside composition includes distributions of NO(+), C(+), N(+), H(+), He(+), CO(2)(+), and 28(+) (a combination of CO(+) and N(2)(+)). The surprising abundance of the nightside ionosphere appears to be maintained by the transport of O(+) from the dayside, leading also to the formation of O(2)(+) through charge exchange with CO(2). Above the exobase, the upper nightside ionosphere exhibits dramatic variability in apparent response to variations in the solar wind and interplanetary magnetic field, with the ionopause extending to several thousand kilometers on one orbit, followed by the complete rertnoval of thermal ions to altitudes below 200 kilometers on the succeeding orbit, 24 hours later. In the upper ionosphere, considerable structure is evident in many of the nightside ion profiles. Also evident are horizontal ion drifts with velocities up to the order of 1 kilometer per second. Whereas the duskside ionopause is dominated by O(+) H(+) dominates the topside on the dawnside of the antisolar point, indicating two separate regions for ion depletion in the magnetic tail regions.

Nesting environment may drive variation in eggshell structure and egg characteristics in the Testudinata.

PubMed

Deeming, D Charles

2018-05-14

Testudines exhibit considerable variation in the degree of eggshell calcification, which affects eggshell conductance, water physiology of the embryos, and calcium metabolism of embryos. However, the underlying reason for different shell types has not been explored. Phylogenetically controlled analyses examined relationships between egg size, shell mass, and clutch size in ∼200 turtle species from a range of body sizes and assigned by family as laying either rigid- or pliable-shelled eggs. Shell type affected egg breadth relative to pelvic dimensions, egg mass, and relative shell mass but did not affect size, mass, or total shell mass of the clutch. These results suggest that calcium availability may be a function of body size and the type of shell may reflect in part the interplay between clutch size and egg size. It was further concluded that the eggshell probably evolved as a means of physical protection. Differences in shell calcification may not primarily reflect reproductive parameters but rather correlate with the acidity of a species' nesting environment. Low pH environments may have thicker calcareous layer to counteract the erosion caused by the soil and maintain the integrity of the physical barrier. Limited calcium availability may constrain clutch size. More neutral nesting substrates expose eggshells to less erosion so calcification per egg can be reduced and this allows larger clutch sizes. This pattern is also reflected in thick, calcified crocodilian eggs. Further research is needed to test whether eggshell calcification in the testudines correlates with nest pH in order to verify this relationship. © 2018 Wiley Periodicals, Inc.

Temporal and spatial variations of greenhouse gas fluxes from a tidal mangrove wetland in Southeast China.

PubMed

Wang, Haitao; Liao, Guanshun; D'Souza, Melissa; Yu, Xiaoqing; Yang, Jun; Yang, Xiaoru; Zheng, Tianling

2016-01-01

Tidal mangrove wetlands are a source of methane (CH4) and nitrous oxide (N2O); but considering the high productivity of mangroves, they represent a significant sink for carbon dioxide (CO2). An exotic plant Spartina alterniflora has invaded east China over the last few decades, threatening these coastal mangrove ecosystems. However, the atmospheric gas fluxes in mangroves are poorly characterized and the impact of biological invasion on greenhouse gas (GHG) fluxes in the wetland remains unclear. In this study, the temporal and spatial dynamics of key GHG fluxes (CO2, CH4, and N2O) at an unvegetated mudflat, cordgrass (S. alterniflora), and mangrove (Kandelia obovata) sites along an estuary of the Jiulong River in Southeast China were investigated over a 2-year period. The CO2 and CH4 fluxes demonstrated a seasonal and vegetation-dependent variation while N2O fluxes showed no such dependent pattern. Air temperature was the main factor influencing CO2 and CH4 fluxes. Cumulative global warming potential (GWP) ranked in the order of mangrove > cordgrass > mudflat and summer > spring > autumn > winter. Moreover, CH4 accounted for the largest proportion (68%) of GWP, indicating its dominant contribution to the warming potential in mangroves. Notwithstanding the lack of information on plant coverage, cordgrass invasion exhibited a minor influence on GHG emissions. These findings support the notion that mangrove forests are net accumulation sites for GHGs. As vegetation showed considerable effects on fluxes, more information about the significance of vegetation type with a special emphasis on the effects of invasive plants is crucial.

Effect of topography-dependent light coupling through a near-field aperture on the local photocurrent of a solar cell.

PubMed

Cao, Zhao; Ermes, Markus; Lehnen, Stephan; Carius, Reinhard; Bittkau, Karsten

2018-01-03

An aperture-type scanning near-field optical microscope (a-SNOM) is readily used for the optical and optoelectronic characterizations of a wide variety of chemical, biological and optoelectronic samples with sub-wavelength optical resolution. These samples mostly exhibit nanoscale topographic variations, which are related to local material inhomogeneity probed either by an optical contrast or by secondary effects such as photoconductivity or photoluminescence. To date, in the interpretation and evaluation of the measurement results from a-SNOM or derived methods, often only the local material inhomogeneity is taken into account. A possible influence of the optical interaction between the scanning probe and the surface topography is rarely discussed. In this paper, we present experimental and theoretical investigation of the effects of nanoscale topographic features on a-SNOM measurement results. We conduct local photocurrent measurements on a thin-film solar cell with an a-SNOM as the illumination source. A clear correlation between the photocurrent response and local topography is observed in all measurements with a signal contrast of up to ∼30%, although the sample features homogeneous permittivity and electrical properties. With the help of finite-difference time-domain (FDTD) simulations, this correlation is reproduced and local light coupling is identified as the mechanism which determines the local photocurrent response. Our results suggest that a-SNOM-based measurements of any sample with material inhomogeneity will be superimposed by the local light-coupling effect if surface topography variation exists. This effect should always be taken into consideration for an accurate interpretation of the measurement results.

A Review of Spatial Variation of Inorganic Nitrogen (N) Wet Deposition in China

PubMed Central

Liu, Lei; Zhang, Xiuying; Wang, Shanqian; Lu, Xuehe; Ouyang, Xiaoying

2016-01-01

Atmospheric nitrogen (N) deposition (Ndep), an important component of the global N cycle, has increased sharply in recent decades in China. Although there were already some studies on Ndep on a national scale, there were some gaps on the magnitude and the spatial patterns of Ndep. In this study, a national-scale Ndep pattern was constructed based on 139 published papers from 2003 to 2014 and the effects of precipitation (P), energy consumption (E) and N fertilizer use (FN) on spatial patterns of Ndep were analyzed. The wet deposition flux of NH4+-N, NO3--N and total Ndep was 6.83, 5.35 and 12.18 kg ha-1 a-1, respectively. Ndep exhibited a decreasing gradient from southeast to northwest of China. Through accuracy assessment of the spatial Ndep distribution and comparisons with other studies, the spatial Ndep distribution by Lu and Tian and this study both gained high accuracy. A strong exponential function was found between P and Ndep, FN and Ndep and E and Ndep, and P and FN had higher contribution than E on the spatial variation of Ndep. Fossil fuel combustion was the main contributor for NO3--N (86.0%) and biomass burning contributed 5.4% on the deposition of NO3--N. The ion of NH4+ was mainly from agricultural activities (85.9%) and fossil fuel combustion (6.0%). Overall, Ndep in China might be considerably affected by the high emissions of NOx and NH3 from fossil fuel combustion and agricultural activities. PMID:26731264

Developmental stage related patterns of codon usage and genomic GC content: searching for evolutionary fingerprints with models of stem cell differentiation

PubMed Central

2007-01-01

Background The usage of synonymous codons shows considerable variation among mammalian genes. How and why this usage is non-random are fundamental biological questions and remain controversial. It is also important to explore whether mammalian genes that are selectively expressed at different developmental stages bear different molecular features. Results In two models of mouse stem cell differentiation, we established correlations between codon usage and the patterns of gene expression. We found that the optimal codons exhibited variation (AT- or GC-ending codons) in different cell types within the developmental hierarchy. We also found that genes that were enriched (developmental-pivotal genes) or specifically expressed (developmental-specific genes) at different developmental stages had different patterns of codon usage and local genomic GC (GCg) content. Moreover, at the same developmental stage, developmental-specific genes generally used more GC-ending codons and had higher GCg content compared with developmental-pivotal genes. Further analyses suggest that the model of translational selection might be consistent with the developmental stage-related patterns of codon usage, especially for the AT-ending optimal codons. In addition, our data show that after human-mouse divergence, the influence of selective constraints is still detectable. Conclusion Our findings suggest that developmental stage-related patterns of gene expression are correlated with codon usage (GC3) and GCg content in stem cell hierarchies. Moreover, this paper provides evidence for the influence of natural selection at synonymous sites in the mouse genome and novel clues for linking the molecular features of genes to their patterns of expression during mammalian ontogenesis. PMID:17349061

Water- and nitrogen-dependent alterations in the inheritance mode of transpiration efficiency in winter wheat at the leaf and whole-plant level.

PubMed

Ratajczak, Dominika; Górny, Andrzej G

2012-11-01

The effects of contrasting water and nitrogen (N) supply on the observed inheritance mode of transpiration efficiency (TE) at the flag-leaf and whole-season levels were examined in winter wheat. Major components of the photosynthetic capacity of leaves and the season-integrated efficiency of water use in vegetative and grain mass formation were evaluated in parental lines of various origins and their diallel F(2)-hybrids grown in a factorial experiment under different moisture and N status of the soil. A broad genetic variation was mainly found for the season-long TE measures. The variation range in the leaf photosynthetic indices was usually narrow, but tended to slightly enhance under water and N shortage. Genotype-treatment interaction effects were significant for most characters. No consistency between the leaf- and season-long TE measures was observed. Preponderance of additivity-dependent variance was mainly identified for the season-integrated TE and leaf CO(2) assimilation rate. Soil treatments exhibited considerable influence on the phenotypic expression of gene action for the residual leaf measures. The contribution of non-additive gene effects and degree of dominance tended to increase in water- and N-limited plants, especially for the leaf transpiration rate and stomatal conductance. The results indicate that promise exists to improve the season-integrated TE. However, selection for TE components should be prolonged for later hybrid generations to eliminate the masking of non-additive causes. Such evaluation among families grown under sub-optimal water and nitrogen supply seems to be the most promising strategy in winter wheat.

Spatial distribution of surface action potentials generated by individual motor units in the human biceps brachii muscle.

PubMed

Rodriguez-Falces, Javier; Negro, Francesco; Gonzalez-Izal, Miriam; Farina, Dario

2013-08-01

This study analyses the spatial distribution of individual motor unit potentials (MUPs) over the skin surface and the influence of motor unit depth and recording configuration on this distribution. Multichannel surface (13×5 electrode grid) and intramuscular (wire electrodes inserted with needles of lengths 15 and 25mm) electromyographic (EMG) signals were concurrently recorded with monopolar derivations from the biceps brachii muscle of 10 healthy subjects during 60-s isometric contractions at 20% of the maximum torque. Multichannel monopolar MUPs of the target motor unit were obtained by spike-triggered averaging of the surface EMG. Amplitude and frequency characteristics of monopolar and bipolar MUPs were calculated for locations along the fibers' direction (longitudinal), and along the direction perpendicular (transverse) to the fibers. In the longitudinal direction, monopolar and bipolar MUPs exhibited marked amplitude changes that extended for 16-32mm and 16-24mm over the innervation and tendon zones, respectively. The variation of monopolar and bipolar MUP characteristics was not symmetrical about the innervation zone. Motor unit depth had a considerable influence on the relative longitudinal variation of amplitude for monopolar MUPs, but not for bipolar MUPs. The transverse extension of bipolar MUPs ranged between 24 and 32mm, whereas that of monopolar MUPs ranged between 72 and 96mm. The mean power spectral frequency of surface MUPs was highly dependent on the transverse electrode location but not on depth. This study provides a basis for the interpretation of the contribution of individual motor units to the interference surface EMG signal. Copyright © 2013 Elsevier Ltd. All rights reserved.

Poster exhibitions at conferences: are we doing it properly?

PubMed

Beamish, Andrew J; Ansell, James; Foster, Jessica J; Foster, Kathryn A; Egan, Richard J

2015-01-01

Literature exploring the educational value and quality of conference poster presentation is scarce. The aim of this study was to identify and describe the variation in poster exhibitions across a spectrum of conferences attended by trainees. Prospective observational assessment of conference posters was carried out across 7 variables at 4 conferences attended by surgical trainees in 2012. Posters were compared by individual variables and according to overall poster score combining all 7 variables examined. The number of authors listed was also compared. Random samples of consecutively numbered posters were examined at the exhibitions of 4 conferences, which included a UK national medical education conference (Association for the Study of Medical Education), a UK international surgical conference (Association of Surgeons of Great Britain and Ireland), a European oncology conference (European Society of Surgical Oncology), and a North American joint medical and surgical conference (Digestive Diseases Week). Significant variation existed between conferences in posters and their presentation. The proportion of presenters failing to display their posters ranged from 3% to 26% (p < 0.0001). Adherence to size guidelines varied from 89% to 100% (p = 0.002). The inclusion of references ranged from 19% to 82% (p < 0.0001). The presence of a presenting author during the allocated session varied widely from 21% to 86% (p < 0.0001). No significant variation was observed in the proportion of posters that were formatted using aims, methods, results, and conclusion sections (81%-93%; p = 0.513) or in the proportion of posters that were identified as difficult to read (24%-28%; p = 0.919). Association for the Study of Medical Education outperformed each of the other exhibitions overall (p < 0.0001). Posters with greater than the median of 4 authors performed significantly better across all areas (p < 0.0001-0.042) except presenter attendance (p = 0.480). Poster exhibitions varied widely, with room for improvement at all 4 conferences. Lessons can be learned by all conferences from each other to improve presenter engagement with and the educational value of poster exhibitions. Copyright © 2014 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Variation in mineral content of red maple sap across an atmospheric deposition gradient

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

McCormick, L.H.

1997-11-01

Xylem sap was collected from red maple (Acer rubrum L.) trees during the spring of 1988 and 1989 at seven forest sites along an atmospheric deposition gradient in north central Pennsylvania and analyzed for pH and twelve mineral constituents. The objectives of the study were to examine the sources and patterns of variation in red maple sap chemistry across an atmospheric deposition gradient and to assess the feasibility of using sap analysis as an indicator of nutrient bioavailability. For most sap constituents, there was considerable spatial and temporal variation in concentration. Sources of variation included within and between site variation,more » date, and year of collection. The nature and extent of variation varied for different constituents. Site differences were similar in 1988 and 1989 for most sap constituents and for some constituents corresponded with differences in soil levels.« less

Long-term Variations of The Solar Activity -- Lower Atmosphere Relationship

NASA Astrophysics Data System (ADS)

Zaitseva, S.; Akhremtchik, S.; Pudovkin, M.; Besser, B.; Rijnbeek, R.

Long-term variations of the air temperature in St.Petersburg, Stockholm, Salzburg and English Midlands are considered. There is shown that in the regions under consider- ation the air temperature distinctly depends on the intensity of the lower atmospheric zonal circulation (Blinova index and North Atlantic Oscillation index (NAO)). In turn, the NAO-index is shown to depend on the solar activity. However, this dependence is rather complicated and exhibits long-period variations associated with secular varia- tions of the solar activity. A possible mechanism of this phenomena is discussed.

Dynamic distribution patterns of ribosomal DNA and chromosomal evolution in Paphiopedilum, a lady's slipper orchid

PubMed Central

2011-01-01

Background Paphiopedilum is a horticulturally and ecologically important genus of ca. 80 species of lady's slipper orchids native to Southeast Asia. These plants have long been of interest regarding their chromosomal evolution, which involves a progressive aneuploid series based on either fission or fusion of centromeres. Chromosome number is positively correlated with genome size, so rearrangement processes must include either insertion or deletion of DNA segments. We have conducted Fluorescence In Situ Hybridization (FISH) studies using 5S and 25S ribosomal DNA (rDNA) probes to survey for rearrangements, duplications, and phylogenetically-correlated variation within Paphiopedilum. We further studied sequence variation of the non-transcribed spacers of 5S rDNA (5S-NTS) to examine their complex duplication history, including the possibility that concerted evolutionary forces may homogenize diversity. Results 5S and 25S rDNA loci among Paphiopedilum species, representing all key phylogenetic lineages, exhibit a considerable diversity that correlates well with recognized evolutionary groups. 25S rDNA signals range from 2 (representing 1 locus) to 9, the latter representing hemizygosity. 5S loci display extensive structural variation, and show from 2 specific signals to many, both major and minor and highly dispersed. The dispersed signals mainly occur at centromeric and subtelomeric positions, which are hotspots for chromosomal breakpoints. Phylogenetic analysis of cloned 5S rDNA non-transcribed spacer (5S-NTS) sequences showed evidence for both ancient and recent post-speciation duplication events, as well as interlocus and intralocus diversity. Conclusions Paphiopedilum species display many chromosomal rearrangements - for example, duplications, translocations, and inversions - but only weak concerted evolutionary forces among highly duplicated 5S arrays, which suggests that double-strand break repair processes are dynamic and ongoing. These results make the genus a model system for the study of complex chromosomal evolution in plants. PMID:21910890

Effects of population succession on demographic and genetic processes: predictions and tests in the daylily Hemerocallis thunbergii (Liliaceae).

PubMed

Chung, Mi Yoon; Nason, John D; Chung, Myong Gi

2007-07-01

Spatial genetic structure within plant populations is influenced by variation in demographic processes through space and time, including a population's successional status. To determine how demographic structure and fine-scale genetic structure (FSGS) change with stages in a population's successional history, we studied Hemerocallis thunbergii (Liliaceae), a nocturnal flowering and hawkmoth-pollinated herbaceous perennial with rapid population turnover dynamics. We examined nine populations assigned to three successive stages of population succession: expansion, maturation, and senescence. We developed stage-specific expectations for within-population demographic and genetic structure, and then for each population quantified the spatial aggregation of individuals and genotypes using spatial autocorrelation methods (nonaccumulative O-ring and kinship statistics, respectively), and at the landscape level measured inbreeding and genetic structure using Wright's F-statistics. Analyses using the O-ring statistic revealed significant aggregation of individuals at short spatial scales in expanding and senescing populations, in particular, which may reflect restricted seed dispersal around maternal individuals combined with relatively low local population densities at these stages. Significant FSGS was found for three of four expanding, no mature, and only one senescing population, a pattern generally consistent with expectations of successional processes. Although allozyme genetic diversity was high within populations (mean %P = 78.9 and H(E) = 0.281), landscape-level differentiation among sites was also high (F(ST) = 0.166) and all populations exhibited a significant deficit of heterozygotes relative to Hardy-Weinberg expectations (range F = 0.201-0.424, mean F(IS) = 0.321). Within populations, F was not correlated with the degree of FSGS, thus suggesting inbreeding due primarily to selfing as opposed to mating among close relatives in spatially structured populations. Our results demonstrate considerable variation in the spatial distribution of individuals and patterns and magnitude of FSGS in H. thunbergii populations across the landscape. This variation is generally consistent with succession-stage-specific differences in ecological processes operating within these populations.

Discordance between genomic divergence and phenotypic variation in a rapidly evolving avian genus (Motacilla).

PubMed

Harris, Rebecca B; Alström, Per; Ödeen, Anders; Leaché, Adam D

2018-03-01

Generally, genotypes and phenotypes are expected to be spatially congruent; however, in widespread species complexes with few barriers to dispersal, multiple contact zones, and limited reproductive isolation, discordance between phenotypes and phylogeographic groups is more probable. Wagtails (Motacilla) are a genus of birds with striking plumage pattern variation across the Old World. Up to 13 subspecies are recognized within a single species, yet previous studies using mitochondrial DNA have supported polyphyletic phylogeographic groups that are inconsistent with subspecies plumage characteristics. In this study, we investigate the link between phenotypes and genotype by taking a phylogenetic approach. We use genome-wide SNPs, nuclear introns, and mitochondrial DNA to estimate population structure, isolation by distance, and species relationships. Together, our genetic sampling includes complete species-level sampling and comprehensive coverage of the three most phenotypically diverse Palearctic species. Our study provides strong evidence for species-level patterns of differentiation, however population-level differentiation is less pronounced. SNPs provide a robust estimate of species-level relationships, which are mostly corroborated by a combined analysis of mtDNA and nuclear introns (the first time-calibrated species tree for the genus). However, the mtDNA tree is strongly incongruent and is considered to misrepresent the species phylogeny. The extant wagtail lineages originated during the Pliocene and the Eurasian lineage underwent rapid diversification during the Pleistocene. Three of four widespread Eurasian species exhibit an east-west divide that contradicts both subspecies taxonomy and phenotypic variation. Indeed, SNPs fail to distinguish between phenotypically distinct subspecies within the M. alba and M. flava complexes, and instead support geographical regions, each of which is home to two or more different looking subspecies. This is a major step towards our understanding of wagtail phylogeny compared to previous analyses of fewer species and considerably less sequence data. Copyright © 2017 Elsevier Inc. All rights reserved.

Honeybee glucose oxidase—its expression in honeybee workers and comparative analyses of its content and H2O2-mediated antibacterial activity in natural honeys

NASA Astrophysics Data System (ADS)

Bucekova, Marcela; Valachova, Ivana; Kohutova, Lenka; Prochazka, Emanuel; Klaudiny, Jaroslav; Majtan, Juraj

2014-08-01

Antibacterial properties of honey largely depend on the accumulation of hydrogen peroxide (H2O2), which is generated by glucose oxidase (GOX)-mediated conversion of glucose in diluted honey. However, honeys exhibit considerable variation in their antibacterial activity. Therefore, the aim of the study was to identify the mechanism behind the variation in this activity and in the H2O2 content in honeys associated with the role of GOX in this process. Immunoblots and in situ hybridization analyses demonstrated that gox is solely expressed in the hypopharyngeal glands of worker bees performing various tasks and not in other glands or tissues. Real-time PCR with reference genes selected for worker heads shows that the gox expression progressively increases with ageing of the youngest bees and nurses and reached the highest values in processor bees. Immunoblot analysis of honey samples revealed that GOX is a regular honey component but its content significantly varied among honeys. Neither botanical source nor geographical origin of honeys affected the level of GOX suggesting that some other factors such as honeybee nutrition and/or genetic/epigenetic factors may take part in the observed variation. A strong correlation was found between the content of GOX and the level of generated H2O2 in honeys except honeydew honeys. Total antibacterial activity of most honey samples against Pseudomonas aeruginosa isolate significantly correlated with the H2O2 content. These results demonstrate that the level of GOX can significantly affect the total antibacterial activity of honey. They also support an idea that breeding of novel honeybee lines expressing higher amounts of GOX could help to increase the antibacterial efficacy of the hypopharyngeal gland secretion that could have positive influence on a resistance of colonies against bacterial pathogens.

Effect of thermal acclimation on organ mass, tissue respiration, and allometry in Leichhardtian river prawns Macrobrachium tolmerum (Riek, 1951).

PubMed

Crispin, Taryn S; White, Craig R

2013-01-01

Changes to an animal's abiotic environment-and consequent changes in the allometry of metabolic rate in the whole animal and its constituent parts-has considerable potential to reveal important patterns in both intraspecific and interindividual variation of metabolic rates. This study demonstrates that, after 6 wk of thermal acclimation at replicate treatments of 16°, 21°, and 25°C, standard metabolic rate (SMR) scales allometrically in Leichhardtian river prawns Macrobrachium tolmerum ([Formula: see text]) and that the scaling exponent and normalization constant of the relationship between SMR and body mass is not significantly different among acclimation treatments when measured at 21°C. There is, however, significant variation among individuals in whole-animal metabolic rate. We hypothesized that these observations may arise because of changes in the metabolic rate and allometry of metabolic rate or mass of organ tissues within the animal. To investigate this hypothesis, rates of oxygen consumption in a range of tissues (gills, gonads, hepatopancreas, chelae muscle, tail muscle) were measured at 21°C and related to the body mass (M) and whole-animal SMR of individual prawns. We demonstrate that thermal acclimation had no effect on organ and tissue mass, that most organ and tissue (gills, gonads, hepatopancreas) respiration rates do not change with acclimation temperature, and that residual variation in the allometry of M. tolmerum SMR is not explained by differences in organ and tissue mass and respiration rates. These results suggest that body size and ambient temperature may independently affect metabolic rate in this species. Both chelae and tail muscle, however, exhibited a reduction in respiration rate in animals acclimated to 25° relative to those acclimated to 16° and 21°C. This reduction in respiration rates of muscle at higher temperatures is evidence of a tissue-specific acclimation response that was not detectable at the whole-animal level.

Distinct Phylogeographic Structures of Wild Radish (Raphanus sativus L. var. raphanistroides Makino) in Japan

PubMed Central

Han, Qingxiang; Higashi, Hiroyuki; Mitsui, Yuki; Setoguchi, Hiroaki

2015-01-01

Coastal plants with simple linear distribution ranges along coastlines provide a suitable system for improving our understanding of patterns of intra-specific distributional history and genetic variation. Due to the combination of high seed longevity and high dispersibility of seeds via seawater, we hypothesized that wild radish would poorly represent phylogeographic structure at the local scale. On the other hand, we also hypothesized that wild radish populations might be geographically differentiated, as has been exhibited by their considerable phenotypic variations along the islands of Japan. We conducted nuclear DNA microsatellite loci and chloroplast DNA haplotype analyses for 486 samples and 144 samples, respectively, from 18 populations to investigate the phylogeographic structure of wild radish in Japan. Cluster analysis supported the existence of differential genetic structures between the Ryukyu Islands and mainland Japan populations. A significant strong pattern of isolation by distance and significant evidence of a recent bottleneck were detected. The chloroplast marker analysis resulted in the generation of eight haplotypes, of which two haplotypes (A and B) were broadly distributed in most wild radish populations. High levels of variation in microsatellite loci were identified, whereas cpDNA displayed low levels of genetic diversity within populations. Our results indicate that the Kuroshio Current would have contributed to the sculpting of the phylogeographic structure by shaping genetic gaps between isolated populations. In addition, the Tokara Strait would have created a geographic barrier between the Ryukyu Islands and mainland Japan. Finally, extant habitat disturbances (coastal erosion), migration patterns (linear expansion), and geographic characteristics (small islands and sea currents) have influenced the expansion and historical population dynamics of wild radish. Our study is the first to record the robust phylogeographic structure in wild radish between the Ryukyu Islands and mainland Japan, and might provide new insight into the genetic differentiation of coastal plants across islands. PMID:26247202

Benchmarking health system performance across districts in Zambia: a systematic analysis of levels and trends in key maternal and child health interventions from 1990 to 2010.

PubMed

Colson, Katherine Ellicott; Dwyer-Lindgren, Laura; Achoki, Tom; Fullman, Nancy; Schneider, Matthew; Mulenga, Peter; Hangoma, Peter; Ng, Marie; Masiye, Felix; Gakidou, Emmanuela

2015-04-02

Achieving universal health coverage and reducing health inequalities are primary goals for an increasing number of health systems worldwide. Timely and accurate measurements of levels and trends in key health indicators at local levels are crucial to assess progress and identify drivers of success and areas that may be lagging behind. We generated estimates of 17 key maternal and child health indicators for Zambia's 72 districts from 1990 to 2010 using surveys, censuses, and administrative data. We used a three-step statistical model involving spatial-temporal smoothing and Gaussian process regression. We generated estimates at the national level for each indicator by calculating the population-weighted mean of the district values and calculated composite coverage as the average of 10 priority interventions. National estimates masked substantial variation across districts in the levels and trends of all indicators. Overall, composite coverage increased from 46% in 1990 to 73% in 2010, and most of this gain was attributable to the scale-up of malaria control interventions, pentavalent immunization, and exclusive breastfeeding. The scale-up of these interventions was relatively equitable across districts. In contrast, progress in routine services, including polio immunization, antenatal care, and skilled birth attendance, stagnated or declined and exhibited large disparities across districts. The absolute difference in composite coverage between the highest-performing and lowest-performing districts declined from 37 to 26 percentage points between 1990 and 2010, although considerable variation in composite coverage across districts persisted. Zambia has made marked progress in delivering maternal and child health interventions between 1990 and 2010; nevertheless, substantial variations across districts and interventions remained. Subnational benchmarking is important to identify these disparities, allowing policymakers to prioritize areas of greatest need. Analyses such as this one should be conducted regularly and feed directly into policy decisions in order to increase accountability at the local, regional, and national levels.

Plasticity of trophic interactions among sharks from the oceanic south-western Indian Ocean revealed by stable isotope and mercury analyses

NASA Astrophysics Data System (ADS)

Kiszka, Jeremy J.; Aubail, Aurore; Hussey, Nigel E.; Heithaus, Michael R.; Caurant, Florence; Bustamante, Paco

2015-02-01

Sharks are a major component of the top predator guild in oceanic ecosystems, but the trophic relationships of many populations remain poorly understood. We examined chemical tracers of diet and habitat (δ15N and δ13C, respectively) and total mercury (Hg) concentrations in muscle tissue of seven pelagic sharks: blue shark (Prionace glauca), short-fin mako shark (Isurus oxyrinchus), oceanic whitetip shark (Carcharhinus longimanus), scalloped hammerhead shark (Sphyrna lewini), pelagic thresher shark (Alopias pelagicus), crocodile shark (Pseudocarcharias kamoharai) and silky shark (Carcharhinus falciformis), from the data poor south-western tropical Indian Ocean. Minimal interspecific variation in mean δ15N values and a large degree of isotopic niche overlap - driven by high intraspecific variation in δ15N values - was observed among pelagic sharks. Similarly, δ13C values of sharks overlapped considerably for all species with the exception of P. glauca, which had more 13C-depleted values indicating possibly longer residence times in purely pelagic waters. Geographic variation in δ13C, δ15N and Hg were observed for P. glauca and I. oxyrinchus. Mean Hg levels were similar among species with the exception of P. kamoharai which had significantly higher Hg concentrations likely related to mesopelagic feeding. Hg concentrations increased with body size in I. oxyrinchus, P. glauca and C. longimanus. Values of δ15N and δ13C varied with size only in P. glauca, suggesting ontogenetic shifts in diets or habitats. Together, isotopic data indicate that - with few exceptions - variance within species in trophic interactions or foraging habitats is greater than differentiation among pelagic sharks in the south-western Indian Ocean. Therefore, it is possible that this group exhibits some level of trophic redundancy, but further studies of diets and fine-scale habitat use are needed to fully test this hypothesis.

Dynamic distribution patterns of ribosomal DNA and chromosomal evolution in Paphiopedilum, a lady's slipper orchid.

PubMed

Lan, Tianying; Albert, Victor A

2011-09-12

Paphiopedilum is a horticulturally and ecologically important genus of ca. 80 species of lady's slipper orchids native to Southeast Asia. These plants have long been of interest regarding their chromosomal evolution, which involves a progressive aneuploid series based on either fission or fusion of centromeres. Chromosome number is positively correlated with genome size, so rearrangement processes must include either insertion or deletion of DNA segments. We have conducted Fluorescence In Situ Hybridization (FISH) studies using 5S and 25S ribosomal DNA (rDNA) probes to survey for rearrangements, duplications, and phylogenetically-correlated variation within Paphiopedilum. We further studied sequence variation of the non-transcribed spacers of 5S rDNA (5S-NTS) to examine their complex duplication history, including the possibility that concerted evolutionary forces may homogenize diversity. 5S and 25S rDNA loci among Paphiopedilum species, representing all key phylogenetic lineages, exhibit a considerable diversity that correlates well with recognized evolutionary groups. 25S rDNA signals range from 2 (representing 1 locus) to 9, the latter representing hemizygosity. 5S loci display extensive structural variation, and show from 2 specific signals to many, both major and minor and highly dispersed. The dispersed signals mainly occur at centromeric and subtelomeric positions, which are hotspots for chromosomal breakpoints. Phylogenetic analysis of cloned 5S rDNA non-transcribed spacer (5S-NTS) sequences showed evidence for both ancient and recent post-speciation duplication events, as well as interlocus and intralocus diversity. Paphiopedilum species display many chromosomal rearrangements--for example, duplications, translocations, and inversions--but only weak concerted evolutionary forces among highly duplicated 5S arrays, which suggests that double-strand break repair processes are dynamic and ongoing. These results make the genus a model system for the study of complex chromosomal evolution in plants.

Between-Site Differences in the Scale of Dispersal and Gene Flow in Red Oak

PubMed Central

Moran, Emily V.; Clark, James S.

2012-01-01

Background Nut-bearing trees, including oaks (Quercus spp.), are considered to be highly dispersal limited, leading to concerns about their ability to colonize new sites or migrate in response to climate change. However, estimating seed dispersal is challenging in species that are secondarily dispersed by animals, and differences in disperser abundance or behavior could lead to large spatio-temporal variation in dispersal ability. Parentage and dispersal analyses combining genetic and ecological data provide accurate estimates of current dispersal, while spatial genetic structure (SGS) can shed light on past patterns of dispersal and establishment. Methodology and Principal Findings In this study, we estimate seed and pollen dispersal and parentage for two mixed-species red oak populations using a hierarchical Bayesian approach. We compare these results to those of a genetic ML parentage model. We also test whether observed patterns of SGS in three size cohorts are consistent with known site history and current dispersal patterns. We find that, while pollen dispersal is extensive at both sites, the scale of seed dispersal differs substantially. Parentage results differ between models due to additional data included in Bayesian model and differing genotyping error assumptions, but both indicate between-site dispersal differences. Patterns of SGS in large adults, small adults, and seedlings are consistent with known site history (farmed vs. selectively harvested), and with long-term differences in seed dispersal. This difference is consistent with predator/disperser satiation due to higher acorn production at the low-dispersal site. While this site-to-site variation results in substantial differences in asymptotic spread rates, dispersal for both sites is substantially lower than required to track latitudinal temperature shifts. Conclusions Animal-dispersed trees can exhibit considerable spatial variation in seed dispersal, although patterns may be surprisingly constant over time. However, even under favorable conditions, migration in heavy-seeded species is likely to lag contemporary climate change. PMID:22563504

Using spatiotemporal statistical models to estimate animal abundance and infer ecological dynamics from survey counts

USGS Publications Warehouse

Conn, Paul B.; Johnson, Devin S.; Ver Hoef, Jay M.; Hooten, Mevin B.; London, Joshua M.; Boveng, Peter L.

2015-01-01

Ecologists often fit models to survey data to estimate and explain variation in animal abundance. Such models typically require that animal density remains constant across the landscape where sampling is being conducted, a potentially problematic assumption for animals inhabiting dynamic landscapes or otherwise exhibiting considerable spatiotemporal variation in density. We review several concepts from the burgeoning literature on spatiotemporal statistical models, including the nature of the temporal structure (i.e., descriptive or dynamical) and strategies for dimension reduction to promote computational tractability. We also review several features as they specifically relate to abundance estimation, including boundary conditions, population closure, choice of link function, and extrapolation of predicted relationships to unsampled areas. We then compare a suite of novel and existing spatiotemporal hierarchical models for animal count data that permit animal density to vary over space and time, including formulations motivated by resource selection and allowing for closed populations. We gauge the relative performance (bias, precision, computational demands) of alternative spatiotemporal models when confronted with simulated and real data sets from dynamic animal populations. For the latter, we analyze spotted seal (Phoca largha) counts from an aerial survey of the Bering Sea where the quantity and quality of suitable habitat (sea ice) changed dramatically while surveys were being conducted. Simulation analyses suggested that multiple types of spatiotemporal models provide reasonable inference (low positive bias, high precision) about animal abundance, but have potential for overestimating precision. Analysis of spotted seal data indicated that several model formulations, including those based on a log-Gaussian Cox process, had a tendency to overestimate abundance. By contrast, a model that included a population closure assumption and a scale prior on total abundance produced estimates that largely conformed to our a priori expectation. Although care must be taken to tailor models to match the study population and survey data available, we argue that hierarchical spatiotemporal statistical models represent a powerful way forward for estimating abundance and explaining variation in the distribution of dynamical populations.

Pelagic larval duration and settlement size of a reef fish are spatially consistent, but post-settlement growth varies at the reef scale

NASA Astrophysics Data System (ADS)

Leahy, Susannah M.; Russ, Garry R.; Abesamis, Rene A.

2015-12-01

Recent research has demonstrated that, despite a pelagic larval stage, many coral reef fishes disperse over relatively small distances, leading to well-connected populations on scales of 0-30 km. Although variation in key biological characteristics has been explored on the scale of 100-1000 s of km, it has rarely been explored at the scale relevant to actual larval dispersal and population connectivity on ecological timescales. In this study, we surveyed the habitat and collected specimens ( n = 447) of juvenile butterflyfish, Chaetodon vagabundus, at nine sites along an 80-km stretch of coastline in the central Philippines to identify variation in key life history parameters at a spatial scale relevant to population connectivity. Mean pelagic larval duration (PLD) was 24.03 d (SE = 0.16 d), and settlement size was estimated to be 20.54 mm total length (TL; SE = 0.61 mm). Both traits were spatially consistent, although this PLD is considerably shorter than that reported elsewhere. In contrast, post-settlement daily growth rates, calculated from otolith increment widths from 1 to 50 d post-settlement, varied strongly across the study region. Elevated growth rates were associated with rocky habitats that this species is known to recruit to, but were strongly negatively correlated with macroalgal cover and exhibited negative density dependence with conspecific juveniles. Larger animals had lower early (first 50 d post-settlement) growth rates than smaller animals, even after accounting for seasonal variation in growth rates. Both VBGF and Gompertz models provided good fits to post-settlement size-at-age data ( n = 447 fish), but the VBGF's estimate of asymptotic length ( L ∞ = 168 mm) was more consistent with field observations of maximum fish length. Our findings indicate that larval characteristics are consistent at the spatial scale at which populations are likely well connected, but that site-level biological differences develop post-settlement, most likely as a result of key differences in quality of recruitment habitat.

A Quarter Century of Variation in Color and Allometric Characteristics of Eggs from a Rain Forest Population of the Pearly-eyed Thrasher (Margarops fuscatus).

Treesearch

WAYNE J. ARENDT

2004-01-01

Egg color, size, and shape vary considerably within and among female Pearly-eyed Thrashers (Margarops fuscatus). Results of a 25-yr study (1979-2004) are presented to provide comparative data. In a sample of 4,128 eggs, typical shape was prolate spheroid; but several variations were observed, depending on the age, stature, and physiological condition of the female, as...

VLSI Architectures and CAD

DTIC Science & Technology

1989-11-01

considerable promise is a variation of the familiar Lempel - Ziv adaptive data compression scheme that permits a straightforward mapping to hardware...types of data . The UNIX " compress " implementation is based upon Terry Welch’s 1984 variation of the Lempel - Ziv method (LZW). One flaw lies in the fact...or more; it must effec- tively compress all types of data (i.e. the algorithm must be universal); the implementation must be contained within a small

Corrosion resistant iron aluminides exhibiting improved mechanical properties and corrosion resistance

DOEpatents

Liu, C.T.; McKamey, C.G.; Tortorelli, P.F.; David, S.A.

1994-06-14

The specification discloses a corrosion-resistant intermetallic alloy comprising, in atomic percent, an FeAl iron aluminide containing from about 30 to about 40% aluminum alloyed with from about 0.01 to 0.4% zirconium and from 0.01 to about 0.8% boron. The alloy exhibits considerably improved room temperature ductility for enhanced usefulness in structural applications. The high temperature strength and fabricability is improved by alloying with molybdenum, carbon, chromium and vanadium. 9 figs.

Corrosion resistant iron aluminides exhibiting improved mechanical properties and corrosion resistance

DOEpatents

Liu, Chain T.; McKamey, Claudette G.; Tortorelli, Peter F.; David, Stan A.

1994-01-01

The specification discloses a corrosion-resistant intermetallic alloy comprising, in atomic percent, an FeAl iron aluminide containing from about 30 to about 40% aluminum alloyed with from about 0.01 to 0.4% zirconium and from 0.01 to about 0.8% boron. The alloy exhibits considerably improved room temperature ductility for enhanced usefulness in structural applications. The high temperature strength and fabricability is improved by alloying with molybdenum, carbon, chromium and vanadium.

Dynamic vertical profiles of peat porewater chemistry in a northern peatland

Treesearch

Natalie A. Griffiths; Stephen D. Sebestyen

2016-01-01

We measured pH, cations, nutrients, and total organic carbon (TOC) over 3 years to examine weekly to monthly variability in porewater chemistry depth profiles (0–3.0 m) in an ombrotrophic bog in Minnesota, USA. We also compared temporal variation at one location to spatial variation in depth profiles at 16 locations across the bog. Most solutes exhibited large...

Freezing and desiccation tolerance in entomopathogenic nematodes: diversity and correlation of traits.

PubMed

Shapiro-Ilan, David I; Brown, Ian; Lewis, Edwin E

2014-03-01

The ability of entomopathogenic nematodes to tolerate environmental stress such as desiccating or freezing conditions, can contribute significantly to biocontrol efficacy. Thus, in selecting which nematode to use in a particular biocontrol program, it is important to be able to predict which strain or species to use in target areas where environmental stress is expected. Our objectives were to (i) compare inter- and intraspecific variation in freeze and desiccation tolerance among a broad array of entomopathogenic nematodes, and (ii) determine if freeze and desiccation tolerance are correlated. In laboratory studies we compared nematodes at two levels of relative humidity (RH) (97% and 85%) and exposure periods (24 and 48 h), and nematodes were exposed to freezing temperatures (-2°C) for 6 or 24 h. To assess interspecific variation, we compared ten species including seven that are of current or recent commercial interest: Heterorhabditis bacteriophora (VS), H. floridensis, H. georgiana, (Kesha), H. indica (HOM1), H. megidis (UK211), Steinernema carpocapsae (All), S. feltiae (SN), S. glaseri (VS), S. rarum (17C&E), and S. riobrave (355). To assess intraspecific variation we compared five strains of H. bacteriophora (Baine, Fl1-1, Hb, Oswego, and VS) and four strains of S. carpocapsae (All, Cxrd, DD136, and Sal), and S. riobrave (355, 38b, 7-12, and TP). S. carpocapsae exhibited the highest level of desiccation tolerance among species followed by S. feltiae and S. rarum; the heterorhabditid species exhibited the least desiccation tolerance and S. riobrave and S. glaseri were intermediate. No intraspecific variation was observed in desiccation tolerance; S. carpocapsae strains showed higher tolerance than all H. bacteriophora or S. riobrave strains yet there was no difference detected within species. In interspecies comparisons, poor freeze tolerance was observed in H. indica, and S. glaseri, S. rarum, and S. riobrave whereas H. georgiana and S. feltiae exhibited the highest freeze tolerance, particularly in the 24-h exposure period. Unlike desiccation tolerance, substantial intraspecies variation in freeze tolerance was observed among H. bacteriophora and S. riobrave strains, yet within species variation was not detected among S. carpocapsae strains. Correlation analysis did not detect a relationship between freezing and desiccation tolerance.

Convergent evolution of sexual shape dimorphism in Diptera.

PubMed

Bonduriansky, Russell

2006-05-01

Several patterns of sexual shape dimorphism, such as male body elongation, eye stalks, or extensions of the exoskeleton, have evolved repeatedly in the true flies (Diptera). Although these dimorphisms may have evolved in response to sexual selection on male body shape, conserved genetic factors may have contributed to this convergent evolution, resulting in stronger phenotypic convergence than might be expected from functional requirements alone. I compared phenotypic variation in body shape in two distantly related species exhibiting sexually dimorphic body elongation: Prochyliza xanthostoma (Piophilidae) and Telostylinus angusticollis (Neriidae). Although sexual selection appears to act differently on male body shape in these species, they exhibited strikingly similar patterns of sexual dimorphism. Likewise, patterns of within-sex shape variation were similar in the two species, particularly in males: relative elongation of the male head capsule, antenna, and legs was associated with reduced head capsule width and wing length, but was nearly independent of variation in thorax length. However, the two species presented contrasting patterns of static allometry: male sexual traits exhibited elevated allometric slopes in T. angusticollis, but not in P. xanthostoma. These results suggest that a shared pattern of covariation among traits may have channeled the evolution of sexually dimorphic body elongation in these species. Nonetheless, static allometries may have been shaped by species-specific selection pressures or genetic architectures. Copyright 2006 Wiley-Liss, Inc.

Assessing intraspecific variation in effective dispersal along an altitudinal gradient: a test in two Mediterranean high-mountain plants.

PubMed

Lara-Romero, Carlos; Robledo-Arnuncio, Juan J; García-Fernández, Alfredo; Iriondo, Jose M

2014-01-01

Plant recruitment depends among other factors on environmental conditions and their variation at different spatial scales. Characterizing dispersal in contrasting environments may thus be necessary to understand natural intraspecific variation in the processes underlying recruitment. Silene ciliata and Armeria caespitosa are two representative species of cryophilic pastures above the tree line in Mediterranean high mountains. No explicit estimations of dispersal kernels have been made so far for these or other high-mountain plants. Such data could help to predict their dispersal and recruitment patterns in a context of changing environments under ongoing global warming. We used an inverse modelling approach to analyse effective seed dispersal patterns in five populations of both Silene ciliata and Armeria caespitosa along an altitudinal gradient in Sierra de Guadarrama (Madrid, Spain). We considered four commonly employed two-dimensional seedling dispersal kernels exponential-power, 2Dt, WALD and log-normal. No single kernel function provided the best fit across all populations, although estimated mean dispersal distances were short (<1 m) in all cases. S. ciliata did not exhibit significant among-population variation in mean dispersal distance, whereas significant differences in mean dispersal distance were found in A. caespitosa. Both S. ciliata and A. caespitosa exhibited among-population variation in the fecundity parameter and lacked significant variation in kernel shape. This study illustrates the complexity of intraspecific variation in the processes underlying recruitment, showing that effective dispersal kernels can remain relatively invariant across populations within particular species, even if there are strong variations in demographic structure and/or physical environment among populations, while the invariant dispersal assumption may not hold for other species in the same environment. Our results call for a case-by-case analysis in a wider range of plant taxa and environments to assess the prevalence and magnitude of intraspecific dispersal variation.

A single-station empirical model for TEC over the Antarctic Peninsula using GPS-TEC data

NASA Astrophysics Data System (ADS)

Feng, Jiandi; Wang, Zhengtao; Jiang, Weiping; Zhao, Zhenzhen; Zhang, Bingbing

2017-02-01

Compared with regional or global total electron content (TEC) empirical models, single-station TEC empirical models may exhibit higher accuracy in describing TEC spatial and temporal variations for a single station. In this paper, a new single-station empirical total electron content (TEC) model, called SSM-month, for the O'Higgins Station in the Antarctic Peninsula is proposed by using Global Positioning System (GPS)-TEC data from 01 January 2004 to 30 June 2015. The diurnal variation of TEC in the O'Higgins Station may have changing features in different months, sometimes even in opposite forms, because of ionospheric phenomena, such as the Mid-latitude Summer Nighttime Anomaly (MSNA). To avoid the influence of different diurnal variations, the concept of monthly modeling is proposed in this study. The SSM-month model, which is established by month (including 12 submodels that correspond to the 12 months), can effectively describe the diurnal variation of TEC in different months. Each submodel of the SSM-month model exhibits good agreement with GPS-TEC input data. Overall, the SSM-month model fits the input data with a bias of 0.03 TECU (total electron content unit, 1 TECU = 1016 el m-2) and a standard deviation of 2.78 TECU. This model, which benefits from the modeling method, can effectively describe the MSNA phenomenon without implementing any modeling correction. TEC data derived from Center for Orbit Determination in Europe global ionosphere maps (CODE GIMs), International Reference Ionosphere 2012 (IRI2012), and NeQuick are compared with the SSM-month model in the years of 2001 and 2015-2016. Result shows that the SSM-month model exhibits good consistency with CODE GIMs, which is better than that of IRI2012 and NeQuick, in the O'Higgins Station on the test days.

Differences in the thermal physiology of adult Yarrow's spiny lizards (Sceloporus jarrovii) in relation to sex and body size.

PubMed

Beal, Martin S; Lattanzio, Matthew S; Miles, Donald B

2014-11-01

Sexual size dimorphism (SSD) is often assumed to reflect the phenotypic consequences of differential selection operating on each sex. Species that exhibit SSD may also show intersexual differences in other traits, including field-active body temperatures, preferred temperatures, and locomotor performance. For these traits, differences may be correlated with differences in body size or reflect sex-specific trait optima. Male and female Yarrow's spiny lizards, Sceloporus jarrovii, in a population in southeastern Arizona exhibit a difference in body temperature that is unrelated to variation in body size. The observed sexual variation in body temperature may reflect divergence in thermal physiology between the sexes. To test this hypothesis, we measured the preferred body temperatures of male and female lizards when recently fed and fasted. We also estimated the thermal sensitivity of stamina at seven body temperatures. Variation in these traits provided an opportunity to determine whether body size or sex-specific variation unrelated to size shaped their thermal physiology. Female lizards, but not males, preferred a lower body temperature when fasted, and this pattern was unrelated to body size. Larger individuals exhibited greater stamina, but we detected no significant effect of sex on the shape or height of the thermal performance curves. The thermal preference of males and females in a thermal gradient exceeded the optimal temperature for performance in both sexes. Our findings suggest that differences in thermal physiology are both sex- and size-based and that peak performance at low body temperatures may be adaptive given the reproductive cycles of this viviparous species. We consider the implications of our findings for the persistence of S. jarrovii and other montane ectotherms in the face of climate warming.

Differences in the thermal physiology of adult Yarrow's spiny lizards (Sceloporus jarrovii) in relation to sex and body size

PubMed Central

Beal, Martin S; Lattanzio, Matthew S; Miles, Donald B

2014-01-01

Sexual size dimorphism (SSD) is often assumed to reflect the phenotypic consequences of differential selection operating on each sex. Species that exhibit SSD may also show intersexual differences in other traits, including field-active body temperatures, preferred temperatures, and locomotor performance. For these traits, differences may be correlated with differences in body size or reflect sex-specific trait optima. Male and female Yarrow's spiny lizards, Sceloporus jarrovii, in a population in southeastern Arizona exhibit a difference in body temperature that is unrelated to variation in body size. The observed sexual variation in body temperature may reflect divergence in thermal physiology between the sexes. To test this hypothesis, we measured the preferred body temperatures of male and female lizards when recently fed and fasted. We also estimated the thermal sensitivity of stamina at seven body temperatures. Variation in these traits provided an opportunity to determine whether body size or sex-specific variation unrelated to size shaped their thermal physiology. Female lizards, but not males, preferred a lower body temperature when fasted, and this pattern was unrelated to body size. Larger individuals exhibited greater stamina, but we detected no significant effect of sex on the shape or height of the thermal performance curves. The thermal preference of males and females in a thermal gradient exceeded the optimal temperature for performance in both sexes. Our findings suggest that differences in thermal physiology are both sex- and size-based and that peak performance at low body temperatures may be adaptive given the reproductive cycles of this viviparous species. We consider the implications of our findings for the persistence of S. jarrovii and other montane ectotherms in the face of climate warming. PMID:25540684

The frequency of Th17 cells in the small intestine exhibits a day-night variation dependent on circadian clock activity.

PubMed

Thu Le, Ha Pham; Nakamura, Yuki; Oh-Oka, Kyoko; Ishimaru, Kayoko; Nakajima, Shotaro; Nakao, Atsuhito

2017-08-19

Interleukin-17-producing CD4 + T helper (Th17) cells are a key immune lineage that protects against bacterial and fungal infections at mucosal surfaces. At steady state, Th17 cells are abundant in the small intestinal mucosa of mice. There are several mechanisms for regulating the population of Th17 cells in the small intestine, reflecting the importance of maintaining their numbers in the correct balance. Here we demonstrate the existence of a time-of-day-dependent variation in the frequency of Th17 cells in the lamina propria of the small intestine in wild-type mice, which was not observed in mice with a loss-of-function mutation of the core circadian gene Clock or in mice housed under aberrant light/dark conditions. Consistent with this, expression of CCL20, a chemokine that regulates homeostatic trafficking of Th17 cells to the small intestine, exhibited circadian rhythms in the small intestine of wild-type, but not Clock-mutated, mice. In support of these observations, the magnitude of ovalbumin (OVA)-specific antibody and T-cell responses in mice sensitized with OVA plus cholera toxin, a mucosal Th17 cell-dependent adjuvant, was correlated with daily variations in the proportion of Th17 cells in the small intestine. These results suggest that the proportion of Th17 cells in the small intestine exhibits a day-night variation in association with CCL20 expression, which depends on circadian clock activity. The findings provide novel insight into the regulation of the Th17 cell population in the small intestine at steady state, which may have translational potential for mucosal vaccination strategies. Copyright © 2017 Elsevier Inc. All rights reserved.

Environmental forcing on life history strategies: Evidence for multi-trophic level responses at ocean basin scales

USGS Publications Warehouse

Suryan, Robert M.; Saba, Vincent S.; Wallace, Bryan P.; Hatch, Scott A.; Frederiksen, Morten; Wanless, Sarah

2009-01-01

Variation in life history traits of organisms is thought to reflect adaptations to environmental forcing occurring from bottom-up and top-down processes. Such variation occurs not only among, but also within species, indicating demographic plasticity in response to environmental conditions. From a broad literature review, we present evidence for ocean basin- and large marine ecosystem-scale variation in intra-specific life history traits, with similar responses occurring among trophic levels from relatively short-lived secondary producers to very long-lived apex predators. Between North Atlantic and North Pacific Ocean basins, for example, species in the Eastern Pacific exhibited either later maturation, lower fecundity, and/or greater annual survival than conspecifics in the Western Atlantic. Parallel variations in life histories among trophic levels also occur in adjacent seas and between eastern vs. western ocean boundaries. For example, zooplankton and seabird species in cooler Barents Sea waters exhibit lower fecundity or greater annual survival than conspecifics in the Northeast Atlantic. Sea turtles exhibit a larger size and a greater reproductive output in the Western Pacific vs. Eastern Pacific. These examples provide evidence for food-web-wide modifications in life history strategies in response to environmental forcing. We hypothesize that such dichotomies result from frequency and amplitude shifts in resource availability over varying temporal and spatial scales. We review data that supports three primary mechanisms by which environmental forcing affects life history strategies: (1) food-web structure; (2) climate variability affecting the quantity and seasonality of primary productivity; (3) bottom-up vs. top-down forcing. These proposed mechanisms provide a framework for comparisons of ecosystem function among oceanic regions (or regimes) and are essential in modeling ecosystem response to climate change, as well as for creating dynamic ecosystem-based marine conservation strategies.

Dry season limnological conditions and basin geology exhibit complex relationships with δ13C and δ15N of carbon sources in four Neotropical floodplains.

PubMed

Zaia Alves, Gustavo H; Hoeinghaus, David J; Manetta, Gislaine I; Benedito, Evanilde

2017-01-01

Studies in freshwater ecosystems are seeking to improve understanding of carbon flow in food webs and stable isotopes have been influential in this work. However, variation in isotopic values of basal production sources could either be an asset or a hindrance depending on study objectives. We assessed the potential for basin geology and local limnological conditions to predict stable carbon and nitrogen isotope values of six carbon sources at multiple locations in four Neotropical floodplain ecosystems (Paraná, Pantanal, Araguaia, and Amazon). Limnological conditions exhibited greater variation within than among systems. δ15N differed among basins for most carbon sources, but δ13C did not (though high within-basin variability for periphyton, phytoplankton and particulate organic carbon was observed). Although δ13C and δ15N values exhibited significant correlations with some limnological factors within and among basins, those relationships differed among carbon sources. Regression trees for both carbon and nitrogen isotopes for all sources depicted complex and in some cases nested relationships, and only very limited similarity was observed among trees for different carbon sources. Although limnological conditions predicted variation in isotope values of carbon sources, we suggest the resulting models were too complex to enable mathematical corrections of source isotope values among sites based on these parameters. The importance of local conditions in determining variation in source isotope values suggest that isotopes may be useful for examining habitat use, dispersal and patch dynamics within heterogeneous floodplain ecosystems, but spatial variability in isotope values needs to be explicitly considered when testing ecosystem models of carbon flow in these systems.

The topside ionospheric effective scale heights (HT) derived with ROCSAT-1 and ground-based Ionosonde observations at equatorial and mid-latitude stations

NASA Astrophysics Data System (ADS)

Ram Sudarsanam, Tulasi; Su, Shin-Yi; Liu, C. H.; Reinisch, Bodo

In this study, we propose the assimilation of topside in situ electron density data from ROCSAT-1 satellite along with the ionosonde measurements for accurate determination of topside iono-spheric effective scale heights (HT) using -Chapman function. The reconstructed topside elec-tron density profiles using these scale heights exhibit an excellent similitude with Jicamarca Incoherent Scatter Radar (ISR) profiles, and are much better representations than the existing methods of Reinisch-Huang method and/or the empirical IRI-2007 model. The main advan-tage with this method is that it allows the precise determination of the effective scale height (HT) and the topside electron density profiles at a dense network of ionosonde/digisonde sta-tions where no ISR facilities are available. The demonstration of the method is applied by investigating the diurnal, seasonal and solar activity variations of HT over the dip-equatorial station Jicamarca and the mid-latitude station Grahamstown. The diurnal variation of scale heights over Jicamarca consistently exhibits a morning time descent followed by a minimum around 0700-0800 LT and a pronounced maximum at noon during all the seasons of both high and moderate solar activity periods. Further, the scale heights exhibit a secondary maximum during the post-sunset hours of equinoctial and summer months, whereas the post-sunset peak is absent during the winter months. These typical features are further investigated using the topside ion properties obtained by ROCSAT-1 as well as SAMI2 model simulations. The re-sults consistently indicate that the diurnal variation of the effective scale height (HT) does not closely follow the plasma temperature variation and at equatorial latitudes is largely controlled by the vertical ExB drift.

The effect of subauroral polarization streams on the mid-latitude thermospheric disturbance neutral winds: a universal time effect

NASA Astrophysics Data System (ADS)

Wang, Hui; Zhang, Kedeng; Zheng, Zhichao; Ridley, Aaron James

2018-03-01

The temporal and spatial variations in thermospheric neutral winds at an altitude of 400 km in response to subauroral polarization streams (SAPS) are investigated using global ionosphere and thermosphere model simulations under the southward interplanetary magnetic field (IMF) condition. During SAPS periods the westward neutral winds in the subauroral latitudes are greatly strengthened at dusk. This is due to the ion drag effect, through which SAPS can accelerate neutral winds in the westward direction. The new findings are that for SAPS commencing at different universal times, the strongest westward neutral winds exhibit large variations in amplitudes. The ion drag and Joule heating effects are dependent on the solar illumination, which exhibit UT variations due to the displacement of the geomagnetic and geographic poles. With more sunlight, stronger westward neutral winds can be generated, and the center of these neutral winds shifts to a later magnetic local time than neutral winds with less solar illumination. In the Northern Hemisphere and Southern Hemisphere, the disturbance neutral wind reaches a maximum at 18:00 and 04:00 UT, and a minimum at 04:00 and 16:00 UT, respectively. There is a good correlation between the neutral wind velocity and cos0.5(SZA) (solar zenith angle). The reduction in the electron density and enhancement in the air mass density at an altitude of 400 km are strongest when the maximum solar illumination collocates with the SAPS. The correlation between the neutral wind velocity and cos0.5(SZA) is also good during the northward IMF period. The effect of a sine-wave oscillation of SAPS on the neutral wind also exhibits UT variations in association with the solar illumination.

Dry season limnological conditions and basin geology exhibit complex relationships with δ13C and δ15N of carbon sources in four Neotropical floodplains

PubMed Central

Hoeinghaus, David J.; Manetta, Gislaine I.; Benedito, Evanilde

2017-01-01

Studies in freshwater ecosystems are seeking to improve understanding of carbon flow in food webs and stable isotopes have been influential in this work. However, variation in isotopic values of basal production sources could either be an asset or a hindrance depending on study objectives. We assessed the potential for basin geology and local limnological conditions to predict stable carbon and nitrogen isotope values of six carbon sources at multiple locations in four Neotropical floodplain ecosystems (Paraná, Pantanal, Araguaia, and Amazon). Limnological conditions exhibited greater variation within than among systems. δ15N differed among basins for most carbon sources, but δ13C did not (though high within-basin variability for periphyton, phytoplankton and particulate organic carbon was observed). Although δ13C and δ15N values exhibited significant correlations with some limnological factors within and among basins, those relationships differed among carbon sources. Regression trees for both carbon and nitrogen isotopes for all sources depicted complex and in some cases nested relationships, and only very limited similarity was observed among trees for different carbon sources. Although limnological conditions predicted variation in isotope values of carbon sources, we suggest the resulting models were too complex to enable mathematical corrections of source isotope values among sites based on these parameters. The importance of local conditions in determining variation in source isotope values suggest that isotopes may be useful for examining habitat use, dispersal and patch dynamics within heterogeneous floodplain ecosystems, but spatial variability in isotope values needs to be explicitly considered when testing ecosystem models of carbon flow in these systems. PMID:28358822

Revision of endemic Marquesas Islands Bidens (Asteraceae, Coreopsideae)

PubMed Central

Wagner, Warren L.; Clark, John R.; Lorence, David H.

2014-01-01

Abstract During the preparation of the Vascular Flora of the Marquesas Islands four new species of Bidens (Coreopsideae, Asteraceae) have come to light and are described herein: Bidens woodii W.L. Wagner, J.R. Clark & Lorence, sp. nov. from Ua Pou, and Bidens microcephala W.L. Wagner, J.R. Clark & Lorence sp. nov., Bidens evapelliana W.L. Wagner, J.R. Clark & Lorence, sp. nov., and Bidens wichmanii W.L. Wagner, J.R. Clark & Lorence, sp. nov. from the undercollected island of Fatu Hiva. In addition to these new species, we recognize the following six species of Bidens previously described from the Marquesas Islands: Bidens beckiana (F. Br.) Sherff (Eiao and Hatutaa), Bidens bipontina Sherff and Bidens cordifolia Sch. Bip. (both in Nuku Hiva), Bidens henryi Sherff (Hiva Oa, Tahuata), Bidens uapensis (F. Br.) Sherff (Ua Pou), and Bidens polycephala Sch. Bip. (Nuku Hiva, Ua Huku, Hiva Oa, Tahuata, and Mohotani). Two names are reduced to synonymy under Bidens polycephala: Bidens collina Degener & Sherff, syn. nov. and Bidens jardinii Sch. Bip., syn. nov. Bidens polycephala has the widest distribution of the Marquesan species on five of the islands and exhibits considerable variation. PMID:25009437

Discharge current distribution in stratified soil under impulse discharge

NASA Astrophysics Data System (ADS)

Eniola Fajingbesi, Fawwaz; Shahida Midi, Nur; Elsheikh, Elsheikh M. A.; Hajar Yusoff, Siti

2017-06-01

The mobility of charge particles traversing a material defines its electrical properties. Soil (earth) have long been the universal grounding before and after the inception of active ground systems for electrical appliance purpose due to it semi-conductive properties. The soil can thus be modelled as a single material exhibiting semi-complex inductive-reactive impedance. Under impulse discharge such as lightning strikes to soil this property of soil could result in electric potential level fluctuation ranging from ground potential rise/fall to electromagnetic pulse coupling that could ultimately fail connected electrical appliance. In this work we have experimentally model the soil and lightning discharge using point to plane electrode setup to observe the current distribution characteristics at different soil conductivity [mS/m] range. The result presented from this research indicate above 5% shift in conductivity before and after discharge which is significant for consideration when dealing with grounding designs. The current distribution in soil have also be successfully observed and analysed from experimental result using mean current magnitude in relation to electrode distance and location, current density variation with depth all showing strong correlation with theoretical assumptions of a semi-complex impedance material.

Effects of exercise on the urinary proteome.

PubMed

Kohler, Maxie; Schänzer, Wilhelm; Thevis, Mario

2015-01-01

Exercise-induced proteinuria has been observed and studied for more than a century. It was found that different sport disciplines alter the urinary proteome in different ways. Moderate-intensity exercise results in increased glomerular filtration, meaning that medium-sized proteins are excreted in higher amounts, while high-intensity exercise of short duration also increases the excretion of low molecular weight proteins as a result of tubular dysfunction. Exhaustive exercise may lead to the excretion of hemoglobin or myoglobin, which changes the urinary proteome considerably. Studies comparing protein maps of different sport types compared to a control group showed that quality and quantity of urinary proteins are interindividually different. In addition, urine samples collected before and after exercise exhibit substantially different protein patterns even from the same person. Therefore, further studies investigating the urinary proteome are desirable. As the variation of protein content and composition in urine are generally much higher than in other matrices, respective studies need to be well controlled and homogenous groups of volunteers should be chosen. In addition to the sport-related physiological and biochemical interest, exercise-induced protein changes also need to be considered for biomarker measurements from urine samples for kidney or other diseases.

The mechanical analysis of thermo-magneto-electric laminated composites in nanoscale with the consideration of surface and flexoelectric effects

NASA Astrophysics Data System (ADS)

Shi, Shuanhu; Li, Peng; Jin, Feng

2018-01-01

A theoretical thermo-magneto-electric (TME) bilayer model is established based on the Hamilton principle, in which both surface effect and flexoelectricity are all taken into account. The governing equations are proposed with the aid of the nonlinear constitutive relations of giant magnetostrictive materials. These equations are general, which can be applied to analyze the coupled extensional, shear and bending deformations at both macroscale and nanoscale. As a specific example, the coupled extensional and bending motion of a slender beam suffering from external magnetic field and thermal variation is investigated, in which the Miller-Shenoy coefficient, magneto-electric (ME) effect, strain gradient and displacement are discussed in detail. After the necessary verification, a critical thickness of the TME model is proposed, below which the surface effect exhibits a remarkable influence on the mechanical behaviors and can not be ignored. It is revealed that the surface effect, flexoelectric effect and temperature increment are beneficial for the enhancement of the induced electric field. This study can provide theoretical basis for the design of nanoscale laminates, especially for the performance evaluation of ME composites under complex environment.

Drosophila Females Undergo Genome Expansion after Interspecific Hybridization

PubMed Central

Romero-Soriano, Valèria; Burlet, Nelly; Vela, Doris; Fontdevila, Antonio; Vieira, Cristina; García Guerreiro, María Pilar

2016-01-01

Genome size (or C-value) can present a wide range of values among eukaryotes. This variation has been attributed to differences in the amplification and deletion of different noncoding repetitive sequences, particularly transposable elements (TEs). TEs can be activated under different stress conditions such as interspecific hybridization events, as described for several species of animals and plants. These massive transposition episodes can lead to considerable genome expansions that could ultimately be involved in hybrid speciation processes. Here, we describe the effects of hybridization and introgression on genome size of Drosophila hybrids. We measured the genome size of two close Drosophila species, Drosophila buzzatii and Drosophila koepferae, their F1 offspring and the offspring from three generations of backcrossed hybrids; where mobilization of up to 28 different TEs was previously detected. We show that hybrid females indeed present a genome expansion, especially in the first backcross, which could likely be explained by transposition events. Hybrid males, which exhibit more variable C-values among individuals of the same generation, do not present an increased genome size. Thus, we demonstrate that the impact of hybridization on genome size can be detected through flow cytometry and is sex-dependent. PMID:26872773

The Neurobiology of Sexual Partner Preferences in Rams

PubMed Central

Roselli, Charles E.; Stormshak, Fred

2009-01-01

The question of what causes a male animal to seek out and choose a female as opposed to another male mating partner is unresolved and remains an issue of considerable debate. The most developed biologic theory is the perinatal organizational hypothesis, which states that perinatal hormone exposure mediates sexual differentiation of the brain. Numerous animal experiments have assessed the contribution of perinatal testosterone and/or estradiol exposure to the development of a male-typical mate preference, but almost all have used hormonally manipulated animals. In contrast, variations in sexual partner preferences occur spontaneously in domestic rams, with as many as 8% of the population exhibiting a preference for same-sex mating partners (male-oriented rams). Thus, the domestic ram is an excellent experimental model to study possible links between fetal neuroendocrine programming of neural mechanisms and adult sexual partner preferences. In this review, we present an overview of sexual differentiation in relation to sexual partner preferences. We then summarize results that test the relevance of the organizational hypothesis to expression of same-sex sexual partner preferences in rams. Finally, we demonstrate that the sexual differentiation of brain and behavior in sheep do not depend critically on aromatization of testosterone to estradiol. PMID:19446078

Dinosaur energetics: setting the bounds on feasible physiologies and ecologies.

PubMed

Clarke, Andrew

2013-09-01

The metabolic status of dinosaurs has long been debated but remains unresolved as no consistent picture has emerged from a range of anatomical and isotopic evidence. Quantitative analysis of dinosaur energetics, based on general principles applicable to all vertebrates, shows that many features of dinosaur lifestyle are compatible with a physiology similar to that of extant lizards, scaled up to dinosaur body masses and temperatures. The analysis suggests that sufficient metabolic scope would have been available to support observed dinosaur growth rates and allow considerable locomotor activity, perhaps even migration. Since at least one dinosaur lineage evolved true endothermy, this study emphasizes there was no single dinosaur physiology. Many small theropods were insulated with feathers and appear to have been partial or full endotherms. Uninsulated small taxa, and all juveniles, presumably would have been ectothermic, with consequent diurnal and seasonal variations in body temperature. In larger taxa, inertial homeothermy would have resulted in warm and stable body temperatures but with a basal metabolism significantly below that of extant mammals or birds of the same size. It would appear that dinosaurs exhibited a range of metabolic levels to match the broad spectrum of ecological niches they occupied.

Characterisation of signal enhancements achieved when utilizing a photon diode in deep Raman spectroscopy of tissue

PubMed Central

Vardaki, Martha Z.; Matousek, Pavel; Stone, Nicholas

2016-01-01

We characterise the performance of a beam enhancing element (‘photon diode’) for use in deep Raman spectroscopy (DRS) of biological tissues. The optical component enhances the number of laser photons coupled into a tissue sample by returning escaping photons back into it at the illumination zone. The method is compatible with transmission Raman spectroscopy, a deep Raman spectroscopy concept, and its implementation leads to considerable enhancement of detected Raman photon rates. In the past, the enhancement concept was demonstrated with a variety of samples (pharmaceutical tablets, tissue, etc) but it was not systematically characterized with biological tissues. In this study, we investigate the enhancing properties of the photon diode in the transmission Raman geometry as a function of: a) the depth and b) the optical properties of tissue samples. Liquid tissue phantoms were employed to facilitate systematic variation of optical properties. These were chosen to mimic optical properties of human tissues, including breast and prostate. The obtained results evidence that a photon diode can enhance Raman signals of tissues by a maximum of × 2.4, although it can also decrease the signals created towards the back of samples that exhibit high scattering or absorption properties. PMID:27375932

Search for methylation-sensitive amplification polymorphisms associated with the mantled variant phenotype in oil palm (Elaeis guineensis Jacq).

PubMed

Jaligot, E; Beulé, T; Baurens, F-C; Billotte, N; Rival, A

2004-02-01

The methylation-sensitive amplification polymorphism (MSAP) technique has been employed on somatic embryo-derived oil palms (Elaeis guineensis Jacq.) to identify methylation polymorphisms correlated with the "mantled" somaclonal variation. The variant phenotype displays an unstable feminization of male organs in both male and female flowers. Using MSAP, the methylation status of CCGG sites was compared in three normal versus three mantled regenerants sampled in clonal populations obtained through somatic embryogenesis from four genotypically distinct mother palms. Overall, 64 selective primer combinations were used and they have amplified 23 markers exhibiting a differential methylation pattern between the two phenotypes. Our results indicate that CCGG sites are poorly affected by the considerable decrease in global DNA methylation that has been previously associated with the mantled phenotype. Each of the 23 markers isolated in the present study could discriminate between the two phenotypes only when they were from the same genetic origin. This result hampers at the moment the direct use of MSAP markers for the early detection of variants, even though valuable information on putative target sequences will be obtained from a further characterization of these polymorphic markers.

Decades of field data reveal that turtles senesce in the wild

PubMed Central

Warner, Daniel A.; Miller, David A. W.; Bronikowski, Anne M.; Janzen, Fredric J.

2016-01-01

Lifespan and aging rates vary considerably across taxa; thus, understanding the factors that lead to this variation is a primary goal in biology and has ramifications for understanding constraints and flexibility in human aging. Theory predicts that senescence—declining reproduction and increasing mortality with advancing age—evolves when selection against harmful mutations is weaker at old ages relative to young ages or when selection favors pleiotropic alleles with beneficial effects early in life despite late-life costs. However, in many long-lived ectotherms, selection is expected to remain strong at old ages because reproductive output typically increases with age, which may lead to the evolution of slow or even negligible senescence. We show that, contrary to current thinking, both reproduction and survival decline with adult age in the painted turtle, Chrysemys picta, based on data spanning >20 y from a wild population. Older females, despite relatively high reproductive output, produced eggs with reduced hatching success. Additionally, age-specific mark–recapture analyses revealed increasing mortality with advancing adult age. These findings of reproductive and mortality senescence challenge the contention that chelonians do not age and more generally provide evidence of reduced fitness at old ages in nonmammalian species that exhibit long chronological lifespans. PMID:27140634

Differential serotonergic innervation of the amygdala in bonobos and chimpanzees

PubMed Central

Barger, Nicole; Taglialatela, Jared P.; Gendron-Fitzpatrick, Annette; Hof, Patrick R.; Hopkins, William D.; Sherwood, Chet C.

2016-01-01

Humans’ closest living relatives are bonobos (Pan paniscus) and chimpanzees (Pan troglodytes), yet these great ape species differ considerably from each other in terms of social behavior. Bonobos are more tolerant of conspecifics in competitive contexts and often use sexual behavior to mediate social interactions. Chimpanzees more frequently employ aggression during conflicts and actively patrol territories between communities. Regulation of emotional responses is facilitated by the amygdala, which also modulates social decision-making, memory and attention. Amygdala responsiveness is further regulated by the neurotransmitter serotonin. We hypothesized that the amygdala of bonobos and chimpanzees would differ in its neuroanatomical organization and serotonergic innervation. We measured volumes of regions and the length density of serotonin transporter-containing axons in the whole amygdala and its lateral, basal, accessory basal and central nuclei. Results showed that accessory basal nucleus volume was larger in chimpanzees than in bonobos. Of particular note, the amygdala of bonobos had more than twice the density of serotonergic axons than chimpanzees, with the most pronounced differences in the basal and central nuclei. These findings suggest that variation in serotonergic innervation of the amygdala may contribute to mediating the remarkable differences in social behavior exhibited by bonobos and chimpanzees. PMID:26475872

Spatiotemporal Characteristics, Determinants and Scenario Analysis of CO2 Emissions in China Using Provincial Panel Data.

PubMed

Wang, Shaojian; Fang, Chuanglin; Li, Guangdong

2015-01-01

This paper empirically investigated the spatiotemporal variations, influencing factors and future emission trends of China's CO2 emissions based on a provincial panel data set. A series of panel econometric models were used taking the period 1995-2011 into consideration. The results indicated that CO2 emissions in China increased over time, and were characterized by noticeable regional discrepancies; in addition, CO2 emissions also exhibited properties of spatial dependence and convergence. Factors such as population scale, economic level and urbanization level exerted a positive influence on CO2 emissions. Conversely, energy intensity was identified as having a negative influence on CO2 emissions. In addition, the significance of the relationship between CO2 emissions and the four variables varied across the provinces based on their scale of economic development. Scenario simulations further showed that the scenario of middle economic growth, middle population increase, low urbanization growth, and high technology improvement (here referred to as Scenario BTU), constitutes the best development model for China to realize the future sustainable development. Based on these empirical findings, we also provide a number of policy recommendations with respect to the future mitigation of CO2 emissions.

Absolutely nondestructive discrimination of Huoshan Dendrobium nobile species with miniature near-infrared (NIR) spectrometer engine.

PubMed

Hu, Tian; Yang, Hai-Long; Tang, Qing; Zhang, Hui; Nie, Lei; Li, Lian; Wang, Jin-Feng; Liu, Dong-Ming; Jiang, Wei; Wang, Fei; Zang, Heng-Chang

2014-10-01

As one very precious traditional Chinese medicine (TCM), Huoshan Dendrobium has not only high price, but also significant pharmaceutical efficacy. However, different species of Huoshan Dendrobium exhibit considerable difference in pharmaceutical efficacy, so rapid and absolutely non-destructive discrimination of Huoshan Dendrobium nobile according to different species is crucial to quality control and pharmaceutical effect. In this study, as one type of miniature near-infrared (NIR) spectrometer, MicroNIR 1700 was used for absolutely nondestructive determination of NIR spectra of 90 batches of Dendrobium from five species of differ- ent commodity grades. The samples were intact and not smashed. Soft independent modeling of class analogy (SIMCA) pattern recognition based on principal component analysis (PCA) was used to classify and recognize different species of Dendrobium samples. The results indicated that the SIMCA qualitative models established with pretreatment method of standard normal variate transformation (SNV) in the spectra range selected by Qs method had 100% recognition rates and 100% rejection rates. This study demonstrated that a rapid and absolutely non-destructive analytical technique based on MicroNIR 1700 spectrometer was developed for successful discrimination of five different species of Huoshan Dendrobium with acceptable accuracy.

The neurobiology of sexual partner preferences in rams.

PubMed

Roselli, Charles E; Stormshak, Fred

2009-05-01

The question of what causes a male animal to seek out and choose a female as opposed to another male mating partner is unresolved and remains an issue of considerable debate. The most developed biologic theory is the perinatal organizational hypothesis, which states that perinatal hormone exposure mediates sexual differentiation of the brain. Numerous animal experiments have assessed the contribution of perinatal testosterone and/or estradiol exposure to the development of a male-typical mate preference, but almost all have used hormonally manipulated animals. In contrast, variations in sexual partner preferences occur spontaneously in domestic rams, with as many as 8% of the population exhibiting a preference for same-sex mating partners (male-oriented rams). Thus, the domestic ram is an excellent experimental model to study possible links between fetal neuroendocrine programming of neural mechanisms and adult sexual partner preferences. In this review, we present an overview of sexual differentiation in relation to sexual partner preferences. We then summarize results that test the relevance of the organizational hypothesis to expression of same-sex sexual partner preferences in rams. Finally, we demonstrate that the sexual differentiation of brain and behavior in sheep does not depend critically on aromatization of testosterone to estradiol.

Hysteretic energy prediction method for mainshock-aftershock sequences

NASA Astrophysics Data System (ADS)

Zhai, Changhai; Ji, Duofa; Wen, Weiping; Li, Cuihua; Lei, Weidong; Xie, Lili

2018-04-01

Structures located in seismically active regions may be subjected to mainshock-aftershock (MSAS) sequences. Strong aftershocks significantly affect the hysteretic energy demand of structures. The hysteretic energy, E H,seq, is normalized by mass m and expressed in terms of the equivalent velocity, V D,seq, to quantitatively investigate aftershock effects on the hysteretic energy of structures. The equivalent velocity, V D,seq, is computed by analyzing the response time-history of an inelastic single-degree-of-freedom (SDOF) system with a varying vibration period subjected to 309 MSAS sequences. The present study selected two kinds of MSAS sequences, with one aftershock and two aftershocks, respectively. The aftershocks are scaled to maintain different relative intensities. The variation of the equivalent velocity, V D,seq, is studied for consideration of the ductility values, site conditions, relative intensities, number of aftershocks, hysteretic models, and damping ratios. The MSAS sequence with one aftershock exhibited a 10% to 30% hysteretic energy increase, whereas the MSAS sequence with two aftershocks presented a 20% to 40% hysteretic energy increase. Finally, a hysteretic energy prediction equation is proposed as a function of the vibration period, ductility value, and damping ratio to estimate hysteretic energy for mainshock-aftershock sequences.

The Generation of Variation and The Developmental Basis for Evolutionary Novelty

PubMed Central

Hallgrímsson, Benedikt; Jamniczky, Heather A.; Young, Nathan M.; Rolian, Campbell; Schmidt-Ott, Urs; Marcucio, Ralph S.

2013-01-01

Organisms exhibit an incredible diversity of form, a fact that makes the evolution of novelty seemingly self-evident. However, despite the “obvious” case for novelty, defining this concept in evolutionary terms is highly problematic, so much so that some have suggested discarding it altogether. Approaches to this problem tend to take either an adaptation or development-based perspective, but we argue here that an exclusive focus on either of these misses the original intent of the novelty concept and undermines its practical utility. We instead propose that for a feature to be novel it must have evolved both by a transition between adaptive peaks on the fitness landscape and that this transition must have overcome a previous developmental constraint. This definition focuses novelty on the explanation of apparently difficult or low probability evolutionary transitions and highlights how the integration of developmental and functional considerations is necessary to evolutionary explanation. It further reinforces that novelty is a central concern not just of evolutionary developmental biology (i.e., “evo-devo”) but of evolutionary biology more generally. We explore this definition of novelty in light of four examples that range from the obvious to subtle. PMID:22649039

In situ oxygen plasma cleaning of microswitch surfaces—comparison of Ti and graphite electrodes

NASA Astrophysics Data System (ADS)

Oh, Changho; Streller, Frank; Ashurst, W. Robert; Carpick, Robert W.; de Boer, Maarten P.

2016-11-01

Ohmic micro- and nanoswitches are of interest for a wide variety of applications including radio frequency communications and as low power complements to transistors. In these switches, it is of paramount importance to maintain surface cleanliness in order to prevent frequent failure by tribopolymer growth. To prepare surfaces, an oxygen plasma clean is expected to be beneficial compared to a high temperature vacuum bakeout because of shorter cleaning time (<5 min compared to ~24 h) and active removal of organic contaminants. We demonstrate that sputtering of the electrode material during oxygen plasma cleaning is a critical consideration for effective cleaning of switch surfaces. With Ti electrodes, a TiO x layer forms that increases electrical contact resistance. When plasma-cleaned using graphite electrodes, the resistance of Pt-coated microswitches exhibit a long lifetime with consistently low resistance (<0.5 Ω variation over 300 million cycles) if the test chamber is refilled with ultra-high purity nitrogen and if the devices are not exposed to laboratory air. Their current-voltage characteristic is also linear at the millivolt level. This is important for nanoswitches which will be operated in that range.

Spatiotemporal Characteristics, Determinants and Scenario Analysis of CO2 Emissions in China Using Provincial Panel Data

PubMed Central

Wang, Shaojian

2015-01-01

This paper empirically investigated the spatiotemporal variations, influencing factors and future emission trends of China’s CO2 emissions based on a provincial panel data set. A series of panel econometric models were used taking the period 1995–2011 into consideration. The results indicated that CO2 emissions in China increased over time, and were characterized by noticeable regional discrepancies; in addition, CO2 emissions also exhibited properties of spatial dependence and convergence. Factors such as population scale, economic level and urbanization level exerted a positive influence on CO2 emissions. Conversely, energy intensity was identified as having a negative influence on CO2 emissions. In addition, the significance of the relationship between CO2 emissions and the four variables varied across the provinces based on their scale of economic development. Scenario simulations further showed that the scenario of middle economic growth, middle population increase, low urbanization growth, and high technology improvement (here referred to as Scenario BTU), constitutes the best development model for China to realize the future sustainable development. Based on these empirical findings, we also provide a number of policy recommendations with respect to the future mitigation of CO2 emissions. PMID:26397373

Subjective Probabilities in Household Surveys

PubMed Central

Hurd, Michael D.

2011-01-01

Subjective probabilities are now collected on a number of large household surveys with the objective of providing data to better understand inter-temporal decision making. Comparison of subjective probabilities with actual outcomes shows that the probabilities have considerable predictive power in situations where individuals have considerable private information such as survival and retirement. In contrast the subjective probability of a stock market gain varies greatly across individuals even though no one has private information and the outcome is the same for everyone. An explanation is that there is considerable variation in accessing and processing information. Further, the subjective probability of a stock market gain is considerably lower than historical averages, providing an explanation for the relatively low frequency of stock holding. An important research objective will be to understand how individuals form their subjective probabilities. PMID:21643535

Deviation diagnosis and analysis of hull flat block assembly based on a state space model

NASA Astrophysics Data System (ADS)

Zhang, Zhiying; Dai, Yinfang; Li, Zhen

2012-09-01

Dimensional control is one of the most important challenges in the shipbuilding industry. In order to predict assembly dimensional variation in hull flat block construction, a variation stream model based on state space was presented in this paper which can be further applied to accuracy control in shipbuilding. Part accumulative error, locating error, and welding deformation were taken into consideration in this model, and variation propagation mechanisms and the accumulative rule in the assembly process were analyzed. Then, a model was developed to describe the variation propagation throughout the assembly process. Finally, an example of flat block construction from an actual shipyard was given. The result shows that this method is effective and useful.

Soil Moisture Memory in Climate Models

NASA Technical Reports Server (NTRS)

Koster, Randal D.; Suarez, Max J.; Zukor, Dorothy J. (Technical Monitor)

2000-01-01

Water balance considerations at the soil surface lead to an equation that relates the autocorrelation of soil moisture in climate models to (1) seasonality in the statistics of the atmospheric forcing, (2) the variation of evaporation with soil moisture, (3) the variation of runoff with soil moisture, and (4) persistence in the atmospheric forcing, as perhaps induced by land atmosphere feedback. Geographical variations in the relative strengths of these factors, which can be established through analysis of model diagnostics and which can be validated to a certain extent against observations, lead to geographical variations in simulated soil moisture memory and thus, in effect, to geographical variations in seasonal precipitation predictability associated with soil moisture. The use of the equation to characterize controls on soil moisture memory is demonstrated with data from the modeling system of the NASA Seasonal-to-Interannual Prediction Project.

An Estimate of Changes in the Sun's Total Irradiance Caused by UV Irradiance Variations from 1874 to 1988

NASA Technical Reports Server (NTRS)

Lean, J.

1990-01-01

Enhanced emission from bright solar faculae is a source of significant variation in the sun's total irradiance. Relative to the emission from the quiet sun, facular emission is known to be considerably greater at UV wavelengths than at visible wavelengths. Determining the spectral dependence of facular emission is of interest for the physical insight this may provide to the origin of the sun's irradiance variations. It is also of interest because solar radiation at lambda less than 300 nm is almost totally absorbed in the Earth's atmosphere. Depending on the magnitude of the UV irradiance variations, changes in the sun's irradiance that penetrates to the Earth's surface may not be equivalent to total irradiance variations measured above the Earth's atmosphere. Using an empirical model of total irradiance variations which accounts separately for changes caused by bright faculae from those associated with dark sunspots, the contribution of UV irradiance variations to changes in the sun's total irradiance is estimated during solar cycles 12 to 21.

DETECTING WATER FLOW BEHIND PIPE IN INJECTION WELLS

EPA Science Inventory

Regulations of the Environmental Protection Agency require that an injection well exhibit both internal and external mechanical integrity. The external mechanical integrity consideration is that there is no significant fluid movement into an underground source of drinking water ...

False Operation of Static Random Access Memory Cells under Alternating Current Power Supply Voltage Variation

NASA Astrophysics Data System (ADS)

Sawada, Takuya; Takata, Hidehiro; Nii, Koji; Nagata, Makoto

2013-04-01

Static random access memory (SRAM) cores exhibit susceptibility against power supply voltage variation. False operation is investigated among SRAM cells under sinusoidal voltage variation on power lines introduced by direct RF power injection. A standard SRAM core of 16 kbyte in a 90 nm 1.5 V technology is diagnosed with built-in self test and on-die noise monitor techniques. The sensitivity of bit error rate is shown to be high against the frequency of injected voltage variation, while it is not greatly influenced by the difference in frequency and phase against SRAM clocking. It is also observed that the distribution of false bits is substantially random in a cell array.

Optimizing chirped laser pulse parameters for electron acceleration in vacuum

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

Akhyani, Mina; Jahangiri, Fazel; Niknam, Ali Reza

2015-11-14

Electron dynamics in the field of a chirped linearly polarized laser pulse is investigated. Variations of electron energy gain versus chirp parameter, time duration, and initial phase of laser pulse are studied. Based on maximizing laser pulse asymmetry, a numerical optimization procedure is presented, which leads to the elimination of rapid fluctuations of gain versus the chirp parameter. Instead, a smooth variation is observed that considerably reduces the accuracy required for experimentally adjusting the chirp parameter.

Cloud Feedback in Atmospheric General Circulation Models: An Update

NASA Technical Reports Server (NTRS)

Cess, R. D.; Zhang, M. H.; Ingram, W. J.; Potter, G. L.; Alekseev, V.; Barker, H. W.; Cohen-Solal, E.; Colman, R. A.; Dazlich, D. A.; DelGenio, A. D.;

Well, what about intraspecific variation? Taxonomic and phylogenetic characters in the genus Synoeca de Saussure (Hymenoptera, Vespidae).

PubMed

Carpenter, James M; Andena, Sergio R; Noll, Fernando B; Wenzel, John W

2013-01-01

Cely and Sarmiento (2011) took issue with the cladistic analysis of relationships among species of the genus Synoeca by Andena et al. (2009a), and presented a reanalysis. They claimed that intraspecific variation in the genus is meaningful, and proper consideration yields a conclusion different from that of Andena et al. Both their critique and reanalysis are vitiated by numerous errors, as is shown in the present paper.

Interactive effects of genotype and food quality on consumer growth rate and elemental content.

PubMed

Prater, Clay; Wagner, Nicole D; Frost, Paul C

2017-05-01

Consumer body stoichiometry is a key trait that links organismal physiology to population and ecosystem-level dynamics. However, as elemental composition has traditionally been considered to be constrained within a species, the ecological and evolutionary factors shaping consumer elemental composition have not been clearly resolved. To this end, we examined the causes and extent of variation in the body phosphorus (P) content and the expression of P-linked traits, mass specific growth rate (MSGR), and P use efficiency (PUE) of the keystone aquatic consumer Daphnia using lake surveys and common garden experiments. While daphnid body %P was relatively constrained in field assemblages sampled across an environmental P gradient, unique genotypes isolated from these lakes showed highly variable phenotypic responses when raised across dietary P gradients in the laboratory. Specifically, we observed substantial inter- and intra-specific variation and differences in daphnid responses within and among our study lakes. While variation in Daphnia body %P was mostly due to plastic phenotypic changes, we documented considerable genetic differences in daphnid MSGR and PUE, and relationships between MSGR and body P content were highly variable among genotypes. Overall, our study found that consumer responses to food quality may differ considerably among genotypes and that relationships between organismal life-history traits and body stoichiometry may be strongly influenced by genetic and environmental variation in natural assemblages. © 2017 by the Ecological Society of America.

Genome-wide investigation of genetic changes during modern breeding of Brassica napus.

PubMed

Wang, Nian; Li, Feng; Chen, Biyun; Xu, Kun; Yan, Guixin; Qiao, Jiangwei; Li, Jun; Gao, Guizhen; Bancroft, Ian; Meng, Jingling; King, Graham J; Wu, Xiaoming

2014-08-01

Considerable genome variation had been incorporated within rapeseed breeding programs over past decades. In past decades, there have been substantial changes in phenotypic properties of rapeseed as a result of extensive breeding effort. Uncovering the underlying patterns of allelic variation in the context of genome organisation would provide knowledge to guide future genetic improvement. We assessed genome-wide genetic changes, including population structure, genetic relatedness, the extent of linkage disequilibrium, nucleotide diversity and genetic differentiation based on F ST outlier detection, for a panel of 472 Brassica napus inbred accessions using a 60 k Brassica Infinium® SNP array. We found genetic diversity varied in different sub-groups. Moreover, the genetic diversity increased from 1950 to 1980 and then remained at a similar level in China and Europe. We also found ~6-10 % genomic regions revealed high F ST values. Some QTLs previously associated with important agronomic traits overlapped with these regions. Overall, the B. napus C genome was found to have more high F ST signals than the A genome, and we concluded that the C genome may contribute more valuable alleles to generate elite traits. The results of this study indicate that considerable genome variation had been incorporated within rapeseed breeding programs over past decades. These results also contribute to understanding the impact of rapeseed improvement on available genome variation and the potential for dissecting complex agronomic traits.

Variational principles for dissipative (sub)systems, with applications to the theory of linear dispersion and geometrical optics

DOE PAGES

Dodin, I. Y.; Zhmoginov, A. I.; Ruiz, D. E.

2017-02-24

Applications of variational methods are typically restricted to conservative systems. Some extensions to dissipative systems have been reported too but require ad hoc techniques such as the artificial doubling of the dynamical variables. We propose a different approach. Here, we show that for a broad class of dissipative systems of practical interest, variational principles can be formulated using constant Lagrange multipliers and Lagrangians nonlocal in time, which allow treating reversible and irreversible dynamics on the same footing. A general variational theory of linear dispersion is formulated as an example. Particularly, we present a variational formulation for linear geometrical optics inmore » a general dissipative medium, which is allowed to be nonstationary, inhomogeneous, anisotropic, and exhibit both temporal and spatial dispersion simultaneously.« less

Optical spectrum variations of IL Cep A

NASA Astrophysics Data System (ADS)

Ismailov, N. Z.; Khalilov, O. V.; Bakhaddinova, G. R.

2016-02-01

The results of many-year uniform spectroscopic observations of the Herbig Ae/Be star IL Cep A are presented. Its Hα line has either a single or a barely resolved two-component emission profile. The H β emission line is clearly divided into two components with a deep central absorption. Smooth variations of the observed parameters of individual spectral lines over nine years are observed. The He I λ5876 Å line has a complex absorption profile, probably with superposed emission components. The NaI D1, D2 doublet exhibits weak changes due to variations in the circumstellar envelope. The variations observed in the stellar spectrum can be explained by either binarity or variations of the magnetic field in the stellar disk. Difficulties associated with both these possibilities are discussed.

46th Annual Gun and Missile Systems Conference and Exhibition. Volume 2. Wednesday

DTIC Science & Technology

2011-09-01

military/systems/munitions/images/ Page 7 Designing for Operational Challenges  Gun hardening – Multiple charges • Angular acceleration variation ...The industrial base overestimated readiness at SDD start – Analysis/models were naive • Impulsive loads — pressure variation — SOM under impulse...Manufacture and Producibility Branch, US Army Armament Research, Development and Engineering Center • Alan Sweet and William Goldberg , Packaging Division

Learned Tactics for Asset Allocation

DTIC Science & Technology

2013-06-01

based on off-policy and on-policy tempo - ral difference learning [6, 31, 47]. The basic prin- ciple that unifies MARL techniques is to identify and...patterns with regu- larities such as symmetry, repetition, and repetition with variation [49, 50, 54]. For example, simply by in- cluding a Gaussian...tactics and policies while still exhibiting variation across the policy geometry. In other words, policies are spread across the substrate in a

Analysis of natural variation in bermudagrass (Cynodon dactylon) reveals physiological responses underlying drought tolerance.

PubMed

Shi, Haitao; Wang, Yanping; Cheng, Zhangmin; Ye, Tiantian; Chan, Zhulong

2012-01-01

Bermudagrass (Cynodon dactylon) is a widely used warm-season turfgrass and one of the most drought tolerant species. Dissecting the natural variation in drought tolerance and physiological responses will bring us powerful basis and novel insight for plant breeding. In the present study, we evaluated the natural variation of drought tolerance among nine bermudagrass varieties by measuring physiological responses after drought stress treatment through withholding water. Three groups differing in drought tolerance were identified, including two tolerant, five moderately tolerant and two susceptible varieties. Under drought stress condition, drought sensitive variety (Yukon) showed relative higher water loss, more severe cell membrane damage (EL), and more accumulation of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA), while drought tolerant variety (Tifgreen) exhibited significantly higher antioxidant enzymes activities. Further results indicated that drought induced cell injury in different varieties (Yukon, SR9554 and Tifgreen) exhibited liner correlation with leaf water content (LWC), H₂O₂ content, MDA content and antioxidant enzyme activities. Additionally, Tifgreen plants had significantly higher levels of osmolytes (proline level and soluble sugars) when compared with Yukon and SR9554 under drought stress condition. Taken together, our results indicated that natural variation of drought stress tolerance in bermudagrass varieties might be largely related to the induced changes of water status, osmolyte accumulation and antioxidant defense system.

Localized Principal Component Analysis based Curve Evolution: A Divide and Conquer Approach

PubMed Central

Appia, Vikram; Ganapathy, Balaji; Yezzi, Anthony; Faber, Tracy

2014-01-01

We propose a novel localized principal component analysis (PCA) based curve evolution approach which evolves the segmenting curve semi-locally within various target regions (divisions) in an image and then combines these locally accurate segmentation curves to obtain a global segmentation. The training data for our approach consists of training shapes and associated auxiliary (target) masks. The masks indicate the various regions of the shape exhibiting highly correlated variations locally which may be rather independent of the variations in the distant parts of the global shape. Thus, in a sense, we are clustering the variations exhibited in the training data set. We then use a parametric model to implicitly represent each localized segmentation curve as a combination of the local shape priors obtained by representing the training shapes and the masks as a collection of signed distance functions. We also propose a parametric model to combine the locally evolved segmentation curves into a single hybrid (global) segmentation. Finally, we combine the evolution of these semilocal and global parameters to minimize an objective energy function. The resulting algorithm thus provides a globally accurate solution, which retains the local variations in shape. We present some results to illustrate how our approach performs better than the traditional approach with fully global PCA. PMID:25520901

Phenotypic plasticity in the scaling of avian basal metabolic rate

PubMed Central

McKechnie, Andrew E; Freckleton, Robert P; Jetz, Walter

2006-01-01

Many birds exhibit short-term, reversible adjustments in basal metabolic rate (BMR), but the overall contribution of phenotypic plasticity to avian metabolic diversity remains unclear. The available BMR data include estimates from birds living in natural environments and captive-raised birds in more homogenous, artificial environments. All previous analyses of interspecific variation in BMR have pooled these data. We hypothesized that phenotypic plasticity is an important contributor to interspecific variation in avian BMR, and that captive-raised populations exhibit general differences in BMR compared to wild-caught populations. We tested this hypothesis by fitting general linear models to BMR data for 231 bird species, using the generalized least-squares approach to correct for phylogenetic relatedness when necessary. The scaling exponent relating BMR to body mass in captive-raised birds (0.670) was significantly shallower than in wild-caught birds (0.744). The differences in metabolic scaling between captive-raised and wild-caught birds persisted when migratory tendency and habitat aridity were controlled for. Our results reveal that phenotypic plasticity is a major contributor to avian interspecific metabolic variation. The finding that metabolic scaling in birds is partly determined by environmental factors provides further support for models that predict variation in scaling exponents, such as the allometric cascade model. PMID:16627278

Progressive erosion of genetic and epigenetic variation in callus-derived cocoa (Theobroma cacao) plants.

PubMed

Rodríguez López, Carlos M; Wetten, Andrew C; Wilkinson, Michael J

2010-06-01

*Relatively little is known about the timing of genetic and epigenetic forms of somaclonal variation arising from callus growth. We surveyed for both types of change in cocoa (Theobroma cacao) plants regenerated from calli of various ages, and also between tissues from the source trees. *For genetic change, we used 15 single sequence repeat (SSR) markers from four source trees and from 233 regenerated plants. For epigenetic change, we used 386 methylation-sensitive amplified polymorphism (MSAP) markers on leaf and explant (staminode) DNA from two source trees and on leaf DNA from 114 regenerants. *Genetic variation within source trees was limited to one slippage mutation in one leaf. Regenerants were far more variable, with 35% exhibiting at least one mutation. Genetic variation initially accumulated with culture age but subsequently declined. MSAP (epigenetic) profiles diverged between leaf and staminode samples from source trees. Multivariate analysis revealed that leaves from regenerants occupied intermediate eigenspace between leaves and staminodes of source plants but became progressively more similar to source tree leaves with culture age. *Statistical analysis confirmed this rather counterintuitive finding that leaves of 'late regenerants' exhibited significantly less genetic and epigenetic divergence from source leaves than those exposed to short periods of callus growth.

D/H Ratios of Marine Lipids from Santa Barbara Basin Sediments

NASA Astrophysics Data System (ADS)

Li, C.; Sessions, A.; Kinnaman, F.; Valentine, D.

2006-12-01

With the early successful application of compound-specific D/H analyses to reconstructing paleoclimate records, most subsequent research has focused on understanding organic D/H fractionations in terrestrial environments. Thus we still know very little about natural D/H variations in lipids derived from marine organisms, or indeed if any such variations exist. We have therefore conducted an extensive survey of lipid δD values in two sediment cores collected in the Santa Barbara Basin. These data allow us to examine 1) variations between the lipid products of different organisms, 2) down-core variations due to diagenesis, and 3) differences between sediments deposited under oxic or anoxic bottom-water conditions. Our results show that considerable D/H variability between different marine products does exist. δD values of n-alkanes (except n-C35) ranged from -94 to -175 ‰, and exhibit a systematic offset between odd and even carbon numbers. The δD value of n-C35 is anomalous at -220‰. Isotopic compositions of n-alkanols range from -126 to -221 , with a pattern of progressive D depletion with chain length observed for free alcohols. δD values of sterols range from -215 to -309‰, and show no systematic variation with carbon number. However, offsets do exist between the saturated, monounsaturated, and diunsaturated sterols. Sterols as a group are strongly depleted in D relative to the bacterial-derived hopanols (-166 to -232‰), suggesting possible differences in biosynthetic fractionations by bacteria and eukaryotes. Phytol and phytane δD values roughly ranged from -360 to -410‰, while phytanol was systematically enriched at -300 to -340‰. Fatty acids encompassed much greater variability, with dD values ranging from -55 to -270‰. In general, saturated fatty acids are enriched in D relative to their unsaturated analogs, and long-chain (>C24) acids are enriched in D relative to short-chain (

Variation in psychotropic drug use in nursing homes.

PubMed

Castle, N G

1998-01-01

Numerous studies of health service use reveal considerable variation in the degree of services provided. In this article the variation in psychotropic drug use in nursing homes is examined. First, a descriptive analysis of nursing homes with and without high levels of psychotropic drug use is provided. Second, an analysis of the determinants of high levels of psychotropic drug use in nursing homes is provided. Factors such as ownership, staffing levels, having special care units, case-mix intensity, competitiveness of the nursing home market, and the state Medicaid reimbursement rate structure are examined. The results of these analyses are discussed in terms of their policy issues.

Modelling supply networks and business cycles as unstable transport phenomena

NASA Astrophysics Data System (ADS)

Helbing, Dirk

2003-07-01

Physical concepts developed to describe instabilities in traffic flows can be generalized in a way that allows one to understand the well-known instability of supply chains (the so-called 'bull-whip effect'). That is, small variations in the consumption rate can cause large variations in the production rate of companies generating the requested product. Interestingly, the resulting oscillations have characteristic frequencies which are considerably lower than the variations in the consumption rate. This suggests that instabilities of supply chains may be the reason for the existence of business cycles. At the same time, we establish some links to queueing theory and between micro- and macroeconomics.

Rationale and methods for an epidemiologic study of cancer among Seventh-Day Adventists.

PubMed

Phillips, R L; Kuzma, J W

1977-12-01

Considerable evidence was found that Adventists are a low-risk population to develop cancer of many sites. Adventists have numerous unique life-style and dietary habits with great variability within the population in adherence to these practices as well as considerable variation in duration of exposure to these characteristics. Thus this study population will likely be extremely productive in identifying dietary habits or other life-style characteristics that are etiologically related to various cancer sites.

Region-specific associations between sex, social status, and oxytocin receptor density in the brains of eusocial rodents.

PubMed

Mooney, S J; Coen, C W; Holmes, M M; Beery, A K

2015-09-10

Naturally occurring variations in neuropeptide receptor distributions in the brain contribute to numerous mammalian social behaviors. In naked mole-rats, which live in large social groups and exhibit remarkable reproductive skew, colony-related social behaviors vary with reproductive status. Here we examined whether variation in social status is associated with variations in the location and/or density of oxytocin binding in this species. Autoradiography was performed to assess forebrain oxytocin receptor (OTR) densities in breeding and non-breeding naked mole-rats of both sexes. Overall, males exhibited higher OTR binding in the medial amygdala in comparison to females. While there were no main effects of reproductive status in any region, a sex difference in OTR binding in the nucleus accumbens was mediated by status. Specifically, breeding males tended to have more OTR binding than breeding females in the nucleus accumbens, while no sex difference was observed in subordinates. These effects suggest that oxytocin may act in a sex- and region-specific way that corresponds to reproductive status and associated social behaviors. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.