Are Attractive Men's Faces Masculine or Feminine? The Importance of Controlling Confounds in Face Stimuli

ERIC Educational Resources Information Center

Debruine, Lisa M.; Jones, Benedict C.; Smith, Finlay G.; Little, Anthony C.

2010-01-01

Women's preferences for male masculinity are highly variable. Although many researchers explain this variability as reflecting systematic individual differences in how women resolve the tradeoff between the costs and benefits of choosing a masculine partner, others suggest that methodological differences between studies are responsible. A recent…

Genetic structure of American chestnut populations based on neutral DNA markers

Treesearch

Thomas L. Kubisiak; James H. Roberds

2006-01-01

Microsatellite and RAPD markers suggest that American chestnut exists as a highly variable species. Even at the margins of its natural range, with a large proportion of its genetic variability occurring within populations (~95%). A statistically significant proportion also exists among population. Although genetic differentiation among populations has taken place, no...

High interannual variability of sea ice thickness in the Arctic region.

PubMed

Laxon, Seymour; Peacock, Neil; Smith, Doug

2003-10-30

Possible future changes in Arctic sea ice cover and thickness, and consequent changes in the ice-albedo feedback, represent one of the largest uncertainties in the prediction of future temperature rise. Knowledge of the natural variability of sea ice thickness is therefore critical for its representation in global climate models. Numerical simulations suggest that Arctic ice thickness varies primarily on decadal timescales owing to changes in wind and ocean stresses on the ice, but observations have been unable to provide a synoptic view of sea ice thickness, which is required to validate the model results. Here we use an eight-year time-series of Arctic ice thickness, derived from satellite altimeter measurements of ice freeboard, to determine the mean thickness field and its variability from 65 degrees N to 81.5 degrees N. Our data reveal a high-frequency interannual variability in mean Arctic ice thickness that is dominated by changes in the amount of summer melt, rather than by changes in circulation. Our results suggest that a continued increase in melt season length would lead to further thinning of Arctic sea ice.

Comparison of High-Frequency Solar Irradiance: Ground Measured vs. Satellite-Derived

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

Lave, Matthew; Weekley, Andrew

2016-11-21

High-frequency solar variability is an important to grid integration studies, but ground measurements are scarce. The high resolution irradiance algorithm (HRIA) has the ability to produce 4-sceond resolution global horizontal irradiance (GHI) samples, at locations across North America. However, the HRIA has not been extensively validated. In this work, we evaluate the HRIA against a database of 10 high-frequency ground-based measurements of irradiance. The evaluation focuses on variability-based metrics. This results in a greater understanding of the errors in the HRIA as well as suggestions for improvement to the HRIA.

Biological and serological variability, evolution and molecular epidemiology of Zucchini yellow mosaic virus (ZYMV, Potyvirus) with special reference to Caribbean islands.

PubMed

Desbiez, C; Wipf-Scheibel, C; Lecoq, H

2002-04-23

Zucchini yellow mosaic virus (ZYMV, Potyvirus) emerged as an important pathogen of cucurbits within the last 20 years. Its origins and mechanisms for evolution and worldwide spread represent important questions to understand plant virus emergence. Sequence analysis on a 250 nucleotide fragment including the N-terminal part of the coat protein coding region, revealed one major group of strains, and some highly divergent isolates from distinct origins. Within the major group, three subsets of strains were defined without correlation with geographic origin, year of collection or biological properties. ZYMV was first observed in Martinique and Guadeloupe in 1992 and 1994, respectively. We studied the evolution of ZYMV variability on both islands in the few years following the putative virus introduction. In Martinique, molecular divergence remained low even after 6 years, suggesting a lack of new introductions. Interactions between strains resulted in a stability of the high biological variability, while the serological diversity decreased and molecular divergence remained low. In Guadeloupe, as in Martinique in 1993, serological variability was high shortly after virus introduction. While the first introduction in Guadeloupe was independent from Martinique, the 'Martinique' type was detected in 1998, suggesting further introductions, maybe through viruliferous aphids or imported plant material.

Airborne black carbon concentrations over an urban region in western India-temporal variability, effects of meteorology, and source regions.

PubMed

Bapna, Mukund; Sunder Raman, Ramya; Ramachandran, S; Rajesh, T A

2013-03-01

This study characterizes over 5 years of high time resolution (5 min), airborne black carbon (BC) concentrations (July 2003 to December 2008) measured over Ahmedabad, an urban region in western India. The data were used to obtain different time averages of BC concentrations, and these averages were then used to assess the diurnal, seasonal, and annual variability of BC over the study region. Assessment of diurnal variations revealed a strong association between BC concentrations and vehicular traffic. Peaks in BC concentration were co-incident with the morning (0730 to 0830, LST) and late evening (1930 to 2030, LST) rush hour traffic. Additionally, diurnal variability in BC concentrations during major festivals (Diwali and Dushera during the months of October/November) revealed an increase in BC concentrations due to fireworks displays. Maximum half hourly BC concentrations during the festival days were as high as 79.8 μg m(-3). However, the high concentrations rapidly decayed suggesting that local meteorology during the festive season was favorable for aerosol dispersion. A multiple linear regression (MLR) model with BC as the dependent variable and meteorological parameters as independent variables was fitted. The variability in temperature, humidity, wind speed, and wind direction accounted for about 49% of the variability in measured BC concentrations. Conditional probability function (CPF) analysis was used to identify the geographical location of local source regions contributing to the effective BC measured (at 880 nm) at the receptor site. The east north-east (ENE) direction to the receptor was identified as a major source region. National highway (NH8) and two coal-fired thermal power stations (at Gandhinagar and Sabarmati) were located in the identified direction, suggesting that local traffic and power plant emissions were likely contributors to the measured BC.

Variability of Organophosphorous Pesticide Metabolite Levels in Spot and 24-hr Urine Samples Collected from Young Children during 1 Week

PubMed Central

Kogut, Katherine; Eisen, Ellen A.; Jewell, Nicholas P.; Quirós-Alcalá, Lesliam; Castorina, Rosemary; Chevrier, Jonathan; Holland, Nina T.; Barr, Dana Boyd; Kavanagh-Baird, Geri; Eskenazi, Brenda

2012-01-01

Background: Dialkyl phosphate (DAP) metabolites in spot urine samples are frequently used to characterize children’s exposures to organophosphorous (OP) pesticides. However, variable exposure and short biological half-lives of OP pesticides could result in highly variable measurements, leading to exposure misclassification. Objective: We examined within- and between-child variability in DAP metabolites in urine samples collected during 1 week. Methods: We collected spot urine samples over 7 consecutive days from 25 children (3–6 years of age). On two of the days, we collected 24-hr voids. We assessed the reproducibility of urinary DAP metabolite concentrations and evaluated the sensitivity and specificity of spot urine samples as predictors of high (top 20%) or elevated (top 40%) weekly average DAP metabolite concentrations. Results: Within-child variance exceeded between-child variance by a factor of two to eight, depending on metabolite grouping. Although total DAP concentrations in single spot urine samples were moderately to strongly associated with concentrations in same-day 24-hr samples (r ≈ 0.6–0.8, p < 0.01), concentrations in spot samples collected > 1 day apart and in 24-hr samples collected 3 days apart were weakly correlated (r ≈ –0.21 to 0.38). Single spot samples predicted high (top 20%) and elevated (top 40%) full-week average total DAP excretion with only moderate sensitivity (≈ 0.52 and ≈ 0.67, respectively) but relatively high specificity (≈ 0.88 and ≈ 0.78, respectively). Conclusions: The high variability we observed in children’s DAP metabolite concentrations suggests that single-day urine samples provide only a brief snapshot of exposure. Sensitivity analyses suggest that classification of cumulative OP exposure based on spot samples is prone to type 2 classification errors. PMID:23052012

Intraindividual variability is related to cognitive change in older adults: evidence for within-person coupling.

PubMed

Bielak, Allison A M; Hultsch, David F; Strauss, Esther; MacDonald, Stuart W S; Hunter, Michael A

2010-09-01

In this study, the authors addressed the longitudinal nature of intraindividual variability over 3 years. A sample of 304 community-dwelling older adults, initially between the ages of 64 and 92 years, completed 4 waves of annual testing on a battery of accuracy- and latency-based tests covering a wide range of cognitive complexity. Increases in response-time inconsistency on moderately and highly complex tasks were associated with increasing age, but there were significant individual differences in change across the entire sample. The time-varying covariation between cognition and inconsistency was significant across the 1-year intervals and remained stable across both time and age. On occasions when intraindividual variability was high, participants' cognitive performance was correspondingly low. The strength of the coupling relationship was greater for more fluid cognitive domains such as memory, reasoning, and processing speed than for more crystallized domains such as verbal ability. Variability based on moderately and highly complex tasks provided the strongest prediction. These results suggest that intraindividual variability is highly sensitive to even subtle changes in cognitive ability. (c) 2010 APA, all rights reserved.

Highly variable recurrence of tsunamis in the 7,400 years before the 2004 Indian Ocean tsunami

NASA Astrophysics Data System (ADS)

Horton, B.; Rubin, C. M.; Sieh, K.; Jessica, P.; Daly, P.; Ismail, N.; Parnell, A. C.

2017-12-01

The devastating 2004 Indian Ocean tsunami caught millions of coastal residents and the scientific community off-guard. Subsequent research in the Indian Ocean basin has identified prehistoric tsunamis, but the timing and recurrence intervals of such events are uncertain. Here, we identify coastal caves as a new depositional environment for reconstructing tsunami records and present a 5,000 year record of continuous tsunami deposits from a coastal cave in Sumatra, Indonesia which shows the irregular recurrence of 11 tsunamis between 7,400 and 2,900 years BP. The data demonstrates that the 2004 tsunami was just the latest in a sequence of devastating tsunamis stretching back to at least the early Holocene and suggests a high likelihood for future tsunamis in the Indian Ocean. The sedimentary record in the cave shows that ruptures of the Sunda megathrust vary between large (which generated the 2004 Indian Ocean tsunami) and smaller slip failures. The chronology of events suggests the recurrence of multiple smaller tsunamis within relatively short time periods, interrupted by long periods of strain accumulation followed by giant tsunamis. The average time period between tsunamis is about 450 years with intervals ranging from a long, dormant period of over 2,000 years, to multiple tsunamis within the span of a century. The very long dormant period suggests that the Sunda megathrust is capable of accumulating large slip deficits between earthquakes. Such a high slip rupture would produce a substantially larger earthquake than the 2004 event. Although there is evidence that the likelihood of another tsunamigenic earthquake in Aceh province is high, these variable recurrence intervals suggest that long dormant periods may follow Sunda Megathrust ruptures as large as that of 2004 Indian Ocean tsunami. The remarkable variability of recurrence suggests that regional hazard mitigation plans should be based upon the high likelihood of future destructive tsunami demonstrated by the cave record and other paleotsunami sites, rather than estimates of recurrence intervals.

BONA FIDE, STRONG-VARIABLE GALACTIC LUMINOUS BLUE VARIABLE STARS ARE FAST ROTATORS: DETECTION OF A HIGH ROTATIONAL VELOCITY IN HR CARINAE

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

Groh, J. H.; Damineli, A.; Moises, A. P.

2009-11-01

We report optical observations of the luminous blue variable (LBV) HR Carinae which show that the star has reached a visual minimum phase in 2009. More importantly, we detected absorptions due to Si IV lambdalambda4088-4116. To match their observed line profiles from 2009 May, a high rotational velocity of v{sub rot} approx = 150 +- 20 km s{sup -1} is needed (assuming an inclination angle of 30 deg.), implying that HR Car rotates at approx =0.88 +- 0.2 of its critical velocity for breakup (v{sub crit}). Our results suggest that fast rotation is typical in all strong-variable, bona fide galacticmore » LBVs, which present S-Dor-type variability. Strong-variable LBVs are located in a well-defined region of the HR diagram during visual minimum (the 'LBV minimum instability strip'). We suggest this region corresponds to where v{sub crit} is reached. To the left of this strip, a forbidden zone with v{sub rot}/v{sub crit}>1 is present, explaining why no LBVs are detected in this zone. Since dormant/ex LBVs like P Cygni and HD 168625 have low v{sub rot}, we propose that LBVs can be separated into two groups: fast-rotating, strong-variable stars showing S-Dor cycles (such as AG Car and HR Car) and slow-rotating stars with much less variability (such as P Cygni and HD 168625). We speculate that supernova (SN) progenitors which had S-Dor cycles before exploding (such as in SN 2001ig, SN 2003bg, and SN 2005gj) could have been fast rotators. We suggest that the potential difficulty of fast-rotating Galactic LBVs to lose angular momentum is additional evidence that such stars could explode during the LBV phase.« less

Diminished heart rate complexity in adolescent girls: a sign of vulnerability to anxiety disorders?

PubMed

Fiol-Veny, Aina; De la Torre-Luque, Alejandro; Balle, Maria; Bornas, Xavier

2018-07-01

Diminished heart rate variability has been found to be associated with high anxiety symptomatology. Since adolescence is the period of onset for many anxiety disorders, this study aimed to determine sex- and anxiety-related differences in heart rate variability and complexity in adolescents. We created four groups according to sex and anxiety symptomatology: high-anxiety girls (n = 24) and boys (n = 25), and low-anxiety girls (n = 22) and boys (n = 24) and recorded their cardiac function while they performed regular school activities. A series of two-way (sex and anxiety) MANOVAs were performed on time domain variability, frequency domain variability, and non-linear complexity. We obtained no multivariate interaction effects between sex and anxiety, but highly anxious participants had lower heart rate variability than the low-anxiety group. Regarding sex, girls showed lower heart rate variability and complexity than boys. The results suggest that adolescent girls have a less flexible cardiac system that could be a marker of the girls' vulnerability to developing anxiety disorders.

Variability of the subtropical mode water in the Southwest Pacific

NASA Astrophysics Data System (ADS)

Fernandez, Denise; Sutton, Philip; Bowen, Melissa

2017-09-01

The variability of Subtropical Mode Water (STMW) in the Southwest Pacific is investigated using a 28 year-long time series (1986-2014) of high-resolution expendable bathythermograph data north of New Zealand (PX06) and a shorter time series, the Roemmich-Gilson monthly Argo optimal interpolation for the 2004-2014 period. The variability in STMW inventories is compared to the variability in air-sea heat fluxes, mixed layer depths and transport of the East Auckland Current (EAUC) to assess both the atmospheric and oceanic roles influencing the formation and decay of STMW. The STMW north of New Zealand has a short lifespan with little persistence of the water mass from 1 year to the next one. Deeper mixed layers and negative anomalies in surface heat fluxes are correlated with increased formation of STMW. The heat content of the STMW layer is anticorrelated with inventories, particularly during the El Niño years. This suggests that large volumes of STMW are coincident with cooler conditions in the prior winter and less oceanic heat storage. There is significant seasonal and interannual variability in STMW inventories, however there are no trends in STMW properties, including its core layer temperature over the last decade. The variability of the winter EAUC transport is highly correlated with the STMW inventories and thermocline depth in the following spring, suggesting ocean dynamics deepen the thermocline and precondition for deeper mixed layers.

Investigating systematic individual differences in sleep-deprived performance on a high-fidelity flight simulator.

PubMed

Van Dongen, Hans P A; Caldwell, John A; Caldwell, J Lynn

2006-05-01

Laboratory research has revealed considerable systematic variability in the degree to which individuals' alertness and performance are affected by sleep deprivation. However, little is known about whether or not different populations exhibit similar levels of individual variability. In the present study, we examined individual variability in performance impairment due to sleep loss in a highly select population of militaryjet pilots. Ten active-duty F-117 pilots were deprived of sleep for 38 h and studied repeatedly in a high-fidelity flight simulator. Data were analyzed with a mixed-model ANOVA to quantify individual variability. Statistically significant, systematic individual differences in the effects of sleep deprivation were observed, even when baseline differences were accounted for. The findings suggest that highly select populations may exhibit individual differences in vulnerability to performance impairment from sleep loss just as the general population does. Thus, the scientific and operational communities' reliance on group data as opposed to individual data may entail substantial misestimation of the impact of job-related stressors on safety and performance.

Spatial variability in plankton biomass and hydrographic variables along an axial transect in Chesapeake Bay

NASA Astrophysics Data System (ADS)

Zhang, X.; Roman, M.; Kimmel, D.; McGilliard, C.; Boicourt, W.

2006-05-01

High-resolution, axial sampling surveys were conducted in Chesapeake Bay during April, July, and October from 1996 to 2000 using a towed sampling device equipped with sensors for depth, temperature, conductivity, oxygen, fluorescence, and an optical plankton counter (OPC). The results suggest that the axial distribution and variability of hydrographic and biological parameters in Chesapeake Bay were primarily influenced by the source and magnitude of freshwater input. Bay-wide spatial trends in the water column-averaged values of salinity were linear functions of distance from the main source of freshwater, the Susquehanna River, at the head of the bay. However, spatial trends in the water column-averaged values of temperature, dissolved oxygen, chlorophyll-a and zooplankton biomass were nonlinear along the axis of the bay. Autocorrelation analysis and the residuals of linear and quadratic regressions between each variable and latitude were used to quantify the patch sizes for each axial transect. The patch sizes of each variable depended on whether the data were detrended, and the detrending techniques applied. However, the patch size of each variable was generally larger using the original data compared to the detrended data. The patch sizes of salinity were larger than those for dissolved oxygen, chlorophyll-a and zooplankton biomass, suggesting that more localized processes influence the production and consumption of plankton. This high-resolution quantification of the zooplankton spatial variability and patch size can be used for more realistic assessments of the zooplankton forage base for larval fish species.

Exome sequence analysis suggests genetic burden contributes to phenotypic variability and complex neuropathy

PubMed Central

Gonzaga-Jauregui, Claudia; Harel, Tamar; Gambin, Tomasz; Kousi, Maria; Griffin, Laurie B.; Francescatto, Ludmila; Ozes, Burcak; Karaca, Ender; Jhangiani, Shalini; Bainbridge, Matthew N.; Lawson, Kim S.; Pehlivan, Davut; Okamoto, Yuji; Withers, Marjorie; Mancias, Pedro; Slavotinek, Anne; Reitnauer, Pamela J; Goksungur, Meryem T.; Shy, Michael; Crawford, Thomas O.; Koenig, Michel; Willer, Jason; Flores, Brittany N.; Pediaditrakis, Igor; Us, Onder; Wiszniewski, Wojciech; Parman, Yesim; Antonellis, Anthony; Muzny, Donna M.; Katsanis, Nicholas; Battaloglu, Esra; Boerwinkle, Eric; Gibbs, Richard A.; Lupski, James R.

2015-01-01

Charcot-Marie-Tooth (CMT) disease is a clinically and genetically heterogeneous distal symmetric polyneuropathy. Whole-exome sequencing (WES) of 40 individuals from 37 unrelated families with CMT-like peripheral neuropathy refractory to molecular diagnosis identified apparent causal mutations in ~45% (17/37) of families. Three candidate disease genes are proposed, supported by a combination of genetic and in vivo studies. Aggregate analysis of mutation data revealed a significantly increased number of rare variants across 58 neuropathy associated genes in subjects versus controls; confirmed in a second ethnically discrete neuropathy cohort, suggesting mutation burden potentially contributes to phenotypic variability. Neuropathy genes shown to have highly penetrant Mendelizing variants (HMPVs) and implicated by burden in families were shown to interact genetically in a zebrafish assay exacerbating the phenotype established by the suppression of single genes. Our findings suggest that the combinatorial effect of rare variants contributes to disease burden and variable expressivity. PMID:26257172

Summer U.S. Surface Air Temperature Variability: Controlling Factors and AMIP Simulation Biases

NASA Astrophysics Data System (ADS)

Merrifield, A.; Xie, S. P.

2016-02-01

This study documents and investigates biases in simulating summer surface air temperature (SAT) variability over the continental U.S. in the Coupled Model Intercomparison Project (CMIP5) Atmospheric Model Intercomparison Project (AMIP). Empirical orthogonal function (EOF) and multivariate regression analyses are used to assess the relative importance of circulation and the land surface feedback at setting summer SAT over a 30-year period (1979-2008). In observations, regions of high SAT variability are closely associated with midtropospheric highs and subsidence, consistent with adiabatic theory (Meehl and Tebaldi 2004, Lau and Nath 2012). Preliminary analysis shows the majority of the AMIP models feature high SAT variability over the central U.S., displaced south and/or west of observed centers of action (COAs). SAT COAs in models tend to be concomitant with regions of high sensible heat flux variability, suggesting an excessive land surface feedback in these models modulate U.S. summer SAT. Additionally, tropical sea surface temperatures (SSTs) play a role in forcing the leading EOF mode for summer SAT, in concert with internal atmospheric variability. There is evidence that models respond to different SST patterns than observed. Addressing issues with the bulk land surface feedback and the SST-forced component of atmospheric variability may be key to improving model skill in simulating summer SAT variability over the U.S.

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

Trends and Divergences in Childhood Income Dynamics, 1970-2010.

PubMed

Hill, Heather D

2018-01-01

Earnings and income variability have increased since the 1970s, particularly at the bottom of the income distribution. Considerable evidence suggests that childhood income levels-captured as average or point-in-time yearly income-are associated with numerous child and adult outcomes. The importance to child development of stable proximal processes during childhood suggests that income variability may also be important, particularly if it is unpredictable, unintentional, or does not reflect an upward trend in family income. Using the Panel Study of Income Dynamics, this study documents trends since the 1970s in three dimensions of childhood income dynamics: level, variability, and growth (n=7991). The analysis reveals that income variability during childhood has grown over time, while income growth rates have not. In addition, the economic context of childhood has diverged substantially by socioeconomic status, race, and family structure, with the most disadvantaged children facing a double-whammy of low income and high variability. © 2018 Elsevier Inc. All rights reserved.

Solar forcing synchronizes decadal North Atlantic climate variability.

PubMed

Thiéblemont, Rémi; Matthes, Katja; Omrani, Nour-Eddine; Kodera, Kunihiko; Hansen, Felicitas

2015-09-15

Quasi-decadal variability in solar irradiance has been suggested to exert a substantial effect on Earth's regional climate. In the North Atlantic sector, the 11-year solar signal has been proposed to project onto a pattern resembling the North Atlantic Oscillation (NAO), with a lag of a few years due to ocean-atmosphere interactions. The solar/NAO relationship is, however, highly misrepresented in climate model simulations with realistic observed forcings. In addition, its detection is particularly complicated since NAO quasi-decadal fluctuations can be intrinsically generated by the coupled ocean-atmosphere system. Here we compare two multi-decadal ocean-atmosphere chemistry-climate simulations with and without solar forcing variability. While the experiment including solar variability simulates a 1-2-year lagged solar/NAO relationship, comparison of both experiments suggests that the 11-year solar cycle synchronizes quasi-decadal NAO variability intrinsic to the model. The synchronization is consistent with the downward propagation of the solar signal from the stratosphere to the surface.

Antarctic lakes suggest millennial reorganizations of Southern Hemisphere atmospheric and oceanic circulation

PubMed Central

Hall, Brenda L.; Denton, George H.; Fountain, Andrew G.; Hendy, Chris H.; Henderson, Gideon M.

2010-01-01

The phasing of millennial-scale oscillations in Antarctica relative to those elsewhere in the world is important for discriminating among models for abrupt climate change, particularly those involving the Southern Ocean. However, records of millennial-scale variability from Antarctica dating to the last glacial maximum are rare and rely heavily on data from widely spaced ice cores, some of which show little variability through that time. Here, we present new data from closed-basin lakes in the Dry Valleys region of East Antarctica that show high-magnitude, high-frequency oscillations in surface level during the late Pleistocene synchronous with climate fluctuations elsewhere in the Southern Hemisphere. These data suggest a coherent Southern Hemisphere pattern of climate change on millennial time scales, at least in the Pacific sector, and indicate that any hypothesis concerning the origin of these events must account for synchronous changes in both high and temperate latitudes. PMID:21115838

Antarctic lakes suggest millennial reorganizations of Southern Hemisphere atmospheric and oceanic circulation.

PubMed

Hall, Brenda L; Denton, George H; Fountain, Andrew G; Hendy, Chris H; Henderson, Gideon M

2010-12-14

The phasing of millennial-scale oscillations in Antarctica relative to those elsewhere in the world is important for discriminating among models for abrupt climate change, particularly those involving the Southern Ocean. However, records of millennial-scale variability from Antarctica dating to the last glacial maximum are rare and rely heavily on data from widely spaced ice cores, some of which show little variability through that time. Here, we present new data from closed-basin lakes in the Dry Valleys region of East Antarctica that show high-magnitude, high-frequency oscillations in surface level during the late Pleistocene synchronous with climate fluctuations elsewhere in the Southern Hemisphere. These data suggest a coherent Southern Hemisphere pattern of climate change on millennial time scales, at least in the Pacific sector, and indicate that any hypothesis concerning the origin of these events must account for synchronous changes in both high and temperate latitudes.

How heart rate variability affects emotion regulation brain networks.

PubMed

Mather, Mara; Thayer, Julian

2018-02-01

Individuals with high heart rate variability tend to have better emotional well-being than those with low heart rate variability, but the mechanisms of this association are not yet clear. In this paper, we propose the novel hypothesis that by inducing oscillatory activity in the brain, high amplitude oscillations in heart rate enhance functional connectivity in brain networks associated with emotion regulation. Recent studies using daily biofeedback sessions to increase the amplitude of heart rate oscillations suggest that high amplitude physiological oscillations have a causal impact on emotional well-being. Because blood flow timing helps determine brain network structure and function, slow oscillations in heart rate have the potential to strengthen brain network dynamics, especially in medial prefrontal regulatory regions that are particularly sensitive to physiological oscillations.

Variable interstellar absorption lines in young stellar aggregates

NASA Astrophysics Data System (ADS)

Krełowski, J.; Strobel, A.; Vješnica, S.; Melekh, D.; Bondar, A.

2018-06-01

The variability of interstellar atomic lines, sporadically reported in the astronomical literature, has been confirmed both in the case of the nearby hot star δ Ori and the very young and violent star-forming region η Carinae, using high-resolution echelle spectra. The presented variability concerns the intensities and profiles of Na I, K I and Ca II. The time-scale of the above-mentioned variations clearly suggests very local phenomena as their cause. It is important to say that not all interstellar lines vary in unison.

Effects of oxygen on responses to heating in two lizard species sampled along an elevational gradient.

PubMed

DuBois, P Mason; Shea, Tanner K; Claunch, Natalie M; Taylor, Emily N

2017-08-01

Thermal tolerance is an important variable in predictive models about the effects of global climate change on species distributions, yet the physiological mechanisms responsible for reduced performance at high temperatures in air-breathing vertebrates are not clear. We conducted an experiment to examine how oxygen affects three variables exhibited by ectotherms as they heat-gaping threshold, panting threshold, and loss of righting response (the latter indicating the critical thermal maximum)-in two lizard species along an elevational (and therefore environmental oxygen partial pressure) gradient. Oxygen partial pressure did not impact these variables in either species. We also exposed lizards at each elevation to severely hypoxic gas to evaluate their responses to hypoxia. Severely low oxygen partial pressure treatments significantly reduced the gaping threshold, panting threshold, and critical thermal maximum. Further, under these extreme hypoxic conditions, these variables were strongly and positively related to partial pressure of oxygen. In an elevation where both species overlapped, the thermal tolerance of the high elevation species was less affected by hypoxia than that of the low elevation species, suggesting the high elevation species may be adapted to lower oxygen partial pressures. In the high elevation species, female lizards had higher thermal tolerance than males. Our data suggest that oxygen impacts the thermal tolerance of lizards, but only under severely hypoxic conditions, possibly as a result of hypoxia-induced anapyrexia. Copyright © 2017. Published by Elsevier Ltd.

The variability puzzle in human memory.

PubMed

Kahana, Michael J; Aggarwal, Eash V; Phan, Tung D

2018-04-26

Memory performance exhibits a high level of variability from moment to moment. Much of this variability may reflect inadequately controlled experimental variables, such as word memorability, past practice and subject fatigue. Alternatively, stochastic variability in performance may largely reflect the efficiency of endogenous neural processes that govern memory function. To help adjudicate between these competing views, the authors conducted a multisession study in which subjects completed 552 trials of a delayed free-recall task. Applying a statistical model to predict variability in each subject's recall performance uncovered modest effects of word memorability, proactive interference, and other variables. In contrast to the limited explanatory power of these experimental variables, performance on the prior list strongly predicted current list recall. These findings suggest that endogenous factors underlying successful encoding and retrieval drive variability in performance. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Mechanism of blood pressure and R-R variability: insights from ganglion blockade in humans

NASA Technical Reports Server (NTRS)

Zhang, Rong; Iwasaki, Kenichi; Zuckerman, Julie H.; Behbehani, Khosrow; Crandall, Craig G.; Levine, Benjamin D.; Blomqvist, C. G. (Principal Investigator)

2002-01-01

Spontaneous blood pressure (BP) and R-R variability are used frequently as 'windows' into cardiovascular control mechanisms. However, the origin of these rhythmic fluctuations is not completely understood. In this study, with ganglion blockade, we evaluated the role of autonomic neural activity versus other 'non-neural' factors in the origin of BP and R-R variability in humans. Beat-to-beat BP, R-R interval and respiratory excursions were recorded in ten healthy subjects (aged 30 +/- 6 years) before and after ganglion blockade with trimethaphan. The spectral power of these variables was calculated in the very low (0.0078-0.05 Hz), low (0.05-0.15 Hz) and high (0.15-0.35 Hz) frequency ranges. The relationship between systolic BP and R-R variability was examined by cross-spectral analysis. After blockade, R-R variability was virtually abolished at all frequencies; however, respiration and high frequency BP variability remained unchanged. Very low and low frequency BP variability was reduced substantially by 84 and 69 %, respectively, but still persisted. Transfer function gain between systolic BP and R-R interval variability decreased by 92 and 88 % at low and high frequencies, respectively, while the phase changed from negative to positive values at the high frequencies. These data suggest that under supine resting conditions with spontaneous breathing: (1) R-R variability at all measured frequencies is predominantly controlled by autonomic neural activity; (2) BP variability at high frequencies (> 0.15 Hz) is mediated largely, if not exclusively, by mechanical effects of respiration on intrathoracic pressure and/or cardiac filling; (3) BP variability at very low and low frequencies (< 0.15 Hz) is probably mediated by both sympathetic nerve activity and intrinsic vasomotor rhythmicity; and (4) the dynamic relationship between BP and R-R variability as quantified by transfer function analysis is determined predominantly by autonomic neural activity rather than other, non-neural factors.

Technical Report Series on Global Modeling and Data Assimilation. Volume 12; Comparison of Satellite Global Rainfall Algorithms

NASA Technical Reports Server (NTRS)

Suarez, Max J. (Editor); Chang, Alfred T. C.; Chiu, Long S.

1997-01-01

Seventeen months of rainfall data (August 1987-December 1988) from nine satellite rainfall algorithms (Adler, Chang, Kummerow, Prabhakara, Huffman, Spencer, Susskind, and Wu) were analyzed to examine the uncertainty of satellite-derived rainfall estimates. The variability among algorithms, measured as the standard deviation computed from the ensemble of algorithms, shows regions of high algorithm variability tend to coincide with regions of high rain rates. Histograms of pattern correlation (PC) between algorithms suggest a bimodal distribution, with separation at a PC-value of about 0.85. Applying this threshold as a criteria for similarity, our analyses show that algorithms using the same sensor or satellite input tend to be similar, suggesting the dominance of sampling errors in these satellite estimates.

Behavioral variability in an evolutionary theory of behavior dynamics.

PubMed

Popa, Andrei; McDowell, J J

2016-03-01

McDowell's evolutionary theory of behavior dynamics (McDowell, 2004) instantiates populations of behaviors (abstractly represented by integers) that evolve under the selection pressure of the environment in the form of positive reinforcement. Each generation gives rise to the next via low-level Darwinian processes of selection, recombination, and mutation. The emergent patterns can be analyzed and compared to those produced by biological organisms. The purpose of this project was to explore the effects of high mutation rates on behavioral variability in environments that arranged different reinforcer rates and magnitudes. Behavioral variability increased with the rate of mutation. High reinforcer rates and magnitudes reduced these effects; low reinforcer rates and magnitudes augmented them. These results are in agreement with live-organism research on behavioral variability. Various combinations of mutation rates, reinforcer rates, and reinforcer magnitudes produced similar high-level outcomes (equifinality). These findings suggest that the independent variables that describe an experimental condition interact; that is, they do not influence behavior independently. These conclusions have implications for the interpretation of high levels of variability, mathematical undermatching, and the matching theory. The last part of the discussion centers on a potential biological counterpart for the rate of mutation, namely spontaneous fluctuations in the brain's default mode network. © 2016 Society for the Experimental Analysis of Behavior.

Why significant variables aren't automatically good predictors.

PubMed

Lo, Adeline; Chernoff, Herman; Zheng, Tian; Lo, Shaw-Hwa

2015-11-10

Thus far, genome-wide association studies (GWAS) have been disappointing in the inability of investigators to use the results of identified, statistically significant variants in complex diseases to make predictions useful for personalized medicine. Why are significant variables not leading to good prediction of outcomes? We point out that this problem is prevalent in simple as well as complex data, in the sciences as well as the social sciences. We offer a brief explanation and some statistical insights on why higher significance cannot automatically imply stronger predictivity and illustrate through simulations and a real breast cancer example. We also demonstrate that highly predictive variables do not necessarily appear as highly significant, thus evading the researcher using significance-based methods. We point out that what makes variables good for prediction versus significance depends on different properties of the underlying distributions. If prediction is the goal, we must lay aside significance as the only selection standard. We suggest that progress in prediction requires efforts toward a new research agenda of searching for a novel criterion to retrieve highly predictive variables rather than highly significant variables. We offer an alternative approach that was not designed for significance, the partition retention method, which was very effective predicting on a long-studied breast cancer data set, by reducing the classification error rate from 30% to 8%.

The Effect of Neighborhood Context on the Relationship Between Substance Misuse and Weapons Aggression in Urban Adolescents Seeking ED Care

PubMed Central

Goldstick, Jason Elliott; Lipton, Robert I.; Carter, Patrick; Stoddard, Sarah A.; Newton, Manya F.; Reischl, Thomas; Walton, Maureen; Zimmerman, Marc A.; Cunningham, Rebecca M.

2015-01-01

Background Frameworks for studying the ecology of human behavior suggest that multiple levels of the environment influence behavior and that these levels interact. Applied to studies of weapons aggression, this suggests proximal risk factor (e.g., substance use) effects may differ across neighborhoods. Objectives To estimate how the association between weapons aggression and substance use varies as a function of several community-level variables. Methods Individual-level measures (demographics, behavioral measures) were obtained from a survey of youth aged 14–24 years old seeking care at a Level-1 ED in Flint, Michigan. Community-level variables were obtained from public sources. Logistic generalized additive models were used to test whether community-level variables (crime rates, alcohol outlets, demographics) modify the link between individual-level substance use variables and the primary outcome measure: self-reported past 6-month weapon (firearm/knife) related aggression. Results The effect of marijuana misuse on weapons aggression varied significantly as a function of five community-level variables: racial composition, vacant housing rates, female headed household rates, density of package alcohol outlets, and nearby drug crime rates. The effect of high-risk alcohol use did not depend on any of the eight community variables tested. Conclusions The relationship between marijuana misuse and weapons aggression differed across neighborhoods with generally less association in more disadvantaged neighborhoods, while high-risk alcohol use showed a consistently high association with weapons aggression that did not vary across neighborhoods. The results aid in understanding the contributions of alcohol and marijuana use to the etiology of weapon-related aggression among urban youth, but further study in the general population is required. PMID:25607807

The Effect of Neighborhood Context on the Relationship Between Substance Misuse and Weapons Aggression in Urban Adolescents Seeking ED Care.

PubMed

Goldstick, Jason Elliott; Lipton, Robert I; Carter, Patrick; Stoddard, Sarah A; Newton, Manya F; Reischl, Thomas; Walton, Maureen; Zimmerman, Marc A; Cunningham, Rebecca M

2015-04-01

Frameworks for studying the ecology of human behavior suggest that multiple levels of the environment influence behavior and that these levels interact. Applied to studies of weapons aggression, this suggests proximal risk factor (e.g., substance use) effects may differ across neighborhoods. To estimate how the association between weapons aggression and substance use varies as a function of several community-level variables. Individual-level measures (demographics, behavioral measures) were obtained from a survey of youth aged 14-24 years old seeking care at a Level-1 ED in Flint, Michigan. Community-level variables were obtained from public sources. Logistic generalized additive models were used to test whether community-level variables (crime rates, alcohol outlets, demographics) modify the link between individual-level substance use variables and the primary outcome measure: self-reported past 6-month weapon (firearm/knife) related aggression. The effect of marijuana misuse on weapons aggression varied significantly as a function of five community-level variables: racial composition, vacant housing rates, female headed household rates, density of package alcohol outlets, and nearby drug crime rates. The effect of high-risk alcohol use did not depend on any of the eight community variables tested. The relationship between marijuana misuse and weapons aggression differed across neighborhoods with generally less association in more disadvantaged neighborhoods, while high-risk alcohol use showed a consistently high association with weapons aggression that did not vary across neighborhoods. The results aid in understanding the contributions of alcohol and marijuana use to the etiology of weapon-related aggression among urban youth, but further study in the general population is required.

The componential processing of fractions in adults and children: effects of stimuli variability and contextual interference

PubMed Central

Gabriel, Florence C.; Szücs, Dénes

2014-01-01

Recent studies have indicated that people have a strong tendency to compare fractions based on constituent numerators or denominators. This is called componential processing. This study explored whether componential processing was preferred in tasks involving high stimuli variability and high contextual interference, when fractions could be compared based either on the holistic values of fractions or on their denominators. Here, stimuli variability referred to the fact that fractions were not monotonous but diversiform. Contextual interference referred to the fact that the processing of fractions was interfered by other stimuli. To our ends, three tasks were used. In Task 1, participants compared a standard fraction 1/5 to unit fractions. This task was used as a low stimuli variability and low contextual interference task. In Task 2 stimuli variability was increased by mixing unit and non-unit fractions. In Task 3, high contextual interference was created by incorporating decimals into fractions. The RT results showed that the processing patterns of fractions were very similar for adults and children. In task 1 and task 3, only componential processing was utilzied. In contrast, both holistic processing and componential processing were utilized in task 2. These results suggest that, if individuals are presented with the opportunity to perform componential processing, both adults and children will tend to do so, even if they are faced with high variability of fractions or high contextual interference. PMID:25249995

The componential processing of fractions in adults and children: effects of stimuli variability and contextual interference.

PubMed

Zhang, Li; Fang, Qiaochu; Gabriel, Florence C; Szücs, Dénes

2014-01-01

Recent studies have indicated that people have a strong tendency to compare fractions based on constituent numerators or denominators. This is called componential processing. This study explored whether componential processing was preferred in tasks involving high stimuli variability and high contextual interference, when fractions could be compared based either on the holistic values of fractions or on their denominators. Here, stimuli variability referred to the fact that fractions were not monotonous but diversiform. Contextual interference referred to the fact that the processing of fractions was interfered by other stimuli. To our ends, three tasks were used. In Task 1, participants compared a standard fraction 1/5 to unit fractions. This task was used as a low stimuli variability and low contextual interference task. In Task 2 stimuli variability was increased by mixing unit and non-unit fractions. In Task 3, high contextual interference was created by incorporating decimals into fractions. The RT results showed that the processing patterns of fractions were very similar for adults and children. In task 1 and task 3, only componential processing was utilzied. In contrast, both holistic processing and componential processing were utilized in task 2. These results suggest that, if individuals are presented with the opportunity to perform componential processing, both adults and children will tend to do so, even if they are faced with high variability of fractions or high contextual interference.

Positive affect and parasympathetic activity: Evidence for a quadratic relationship between feeling safe and content and heart rate variability.

PubMed

Duarte, Joana; Pinto-Gouveia, José

2017-11-01

There has been an increased interest in the study of underlying autonomic correlates of emotions. This study tests the hypothesis that high levels of high-frequency heart rate variability (HF HRV) are associated with positive emotions. In addition, we hypothesize that this association will differ according to the type of positive emotion. Also, based on recent findings, we tested the hypothesis that this relationship would be nonlinear. Resting-state HRV was collected and self-report measures of different positive emotions were administered to a sample of 124 volunteers. Results suggested that there was a quadratic relationship between high-frequency heart rate variability and positive emotions associated with safeness and contentment, but not with positive emotions associated with excitement or lack of arousal. Our data suggests that different positive emotions may be characterized by qualitatively distinct profiles of autonomic activation. Also, given the role of positive emotions in social affiliation, and particularly positive emotions associated with a quiescence motivational state, results are interpreted in light of theoretical accounts that highlight the importance of vagal regulation for social behavior. Copyright © 2017 Elsevier B.V. All rights reserved.

Individual differences and time-varying features of modular brain architecture.

PubMed

Liao, Xuhong; Cao, Miao; Xia, Mingrui; He, Yong

2017-05-15

Recent studies have suggested that human brain functional networks are topologically organized into functionally specialized but inter-connected modules to facilitate efficient information processing and highly flexible cognitive function. However, these studies have mainly focused on group-level network modularity analyses using "static" functional connectivity approaches. How these extraordinary modular brain structures vary across individuals and spontaneously reconfigure over time remain largely unknown. Here, we employed multiband resting-state functional MRI data (N=105) from the Human Connectome Project and a graph-based modularity analysis to systematically investigate individual variability and dynamic properties in modular brain networks. We showed that the modular structures of brain networks dramatically vary across individuals, with higher modular variability primarily in the association cortex (e.g., fronto-parietal and attention systems) and lower variability in the primary systems. Moreover, brain regions spontaneously changed their module affiliations on a temporal scale of seconds, which cannot be simply attributable to head motion and sampling error. Interestingly, the spatial pattern of intra-subject dynamic modular variability largely overlapped with that of inter-subject modular variability, both of which were highly reproducible across repeated scanning sessions. Finally, the regions with remarkable individual/temporal modular variability were closely associated with network connectors and the number of cognitive components, suggesting a potential contribution to information integration and flexible cognitive function. Collectively, our findings highlight individual modular variability and the notable dynamic characteristics in large-scale brain networks, which enhance our understanding of the neural substrates underlying individual differences in a variety of cognition and behaviors. Copyright © 2017 Elsevier Inc. All rights reserved.

Subjective Social Status and Cardiovascular Reactivity: An Experimental Examination

PubMed Central

Pieritz, Karoline; Süssenbach, Philipp; Rief, Winfried; Euteneuer, Frank

2016-01-01

The present experiment examined the causal influence of subjective social status (SSS) on variables related to cardiovascular health [i.e., blood pressure, heart rate variability (HRV)]. Participants were randomly assigned to one of two conditions involving a social comparison that either induced a temporary shift toward high SSS or toward low SSS. Cardiovascular variables were measured before (baseline), throughout, and after the manipulation (recovery). Participants in the low SSS condition had a significantly lower HRV during experimental manipulation than at baseline (p = 0.001). They also showed a significantly stronger HRV reactivity compared to participants in the high SSS condition (p = 0.027). Our results suggest that already temporary shifts of one's SSS have measureable effects on cardiovascular variables. They support the notion that social status plays a causal role in the development of cardiovascular disease. PMID:27486426

Little Ice Age climatic erraticism as an analogue for future enhanced hydroclimatic variability across the American Southwest

PubMed Central

Loisel, Julie; MacDonald, Glen M.; Thomson, Marcus J.

2017-01-01

The American Southwest has experienced a series of severe droughts interspersed with strong wet episodes over the past decades, prompting questions about future climate patterns and potential intensification of weather disruptions under warming conditions. Here we show that interannual hydroclimatic variability in this region has displayed a significant level of non-stationarity over the past millennium. Our tree ring-based analysis of past drought indicates that the Little Ice Age (LIA) experienced high interannual hydroclimatic variability, similar to projections for the 21st century. This is contrary to the Medieval Climate Anomaly (MCA), which had reduced variability and therefore may be misleading as an analog for 21st century warming, notwithstanding its warm (and arid) conditions. Given past non-stationarity, and particularly erratic LIA, a ‘warm LIA’ climate scenario for the coming century that combines high precipitation variability (similar to LIA conditions) with warm and dry conditions (similar to MCA conditions) represents a plausible situation that is supported by recent climate simulations. Our comparison of tree ring-based drought analysis and records from the tropical Pacific Ocean suggests that changing variability in El Niño Southern Oscillation (ENSO) explains much of the contrasting variances between the MCA and LIA conditions across the American Southwest. Greater ENSO variability for the 21st century could be induced by a decrease in meridional sea surface temperature gradient caused by increased greenhouse gas concentration, as shown by several recent climate modeling experiments. Overall, these results coupled with the paleo-record suggests that using the erratic LIA conditions as benchmarks for past hydroclimatic variability can be useful for developing future water-resource management and drought and flood hazard mitigation strategies in the Southwest. PMID:29036207

Region-Specific Sensitivity of Anemophilous Pollen Deposition to Temperature and Precipitation

PubMed Central

Donders, Timme H.; Hagemans, Kimberley; Dekker, Stefan C.; de Weger, Letty A.; de Klerk, Pim; Wagner-Cremer, Friederike

2014-01-01

Understanding relations between climate and pollen production is important for several societal and ecological challenges, importantly pollen forecasting for pollinosis treatment, forensic studies, global change biology, and high-resolution palaeoecological studies of past vegetation and climate fluctuations. For these purposes, we investigate the role of climate variables on annual-scale variations in pollen influx, test the regional consistency of observed patterns, and evaluate the potential to reconstruct high-frequency signals from sediment archives. A 43-year pollen-trap record from the Netherlands is used to investigate relations between annual pollen influx, climate variables (monthly and seasonal temperature and precipitation values), and the North Atlantic Oscillation climate index. Spearman rank correlation analysis shows that specifically in Alnus, Betula, Corylus, Fraxinus, Quercus and Plantago both temperature in the year prior to (T-1), as well as in the growing season (T), are highly significant factors (TApril rs between 0.30 [P<0.05[ and 0.58 [P<0.0001]; TJuli-1 rs between 0.32 [P<0.05[ and 0.56 [P<0.0001]) in the annual pollen influx of wind-pollinated plants. Total annual pollen prediction models based on multiple climate variables yield R2 between 0.38 and 0.62 (P<0.0001). The effect of precipitation is minimal. A second trapping station in the SE Netherlands, shows consistent trends and annual variability, suggesting the climate factors are regionally relevant. Summer temperature is thought to influence the formation of reproductive structures, while temperature during the flowering season influences pollen release. This study provides a first predictive model for seasonal pollen forecasting, and also aides forensic studies. Furthermore, variations in pollen accumulation rates from a sub-fossil peat deposit are comparable with the pollen trap data. This suggests that high frequency variability pollen records from natural archives reflect annual past climate variability, and can be used in palaeoecological and -climatological studies to bridge between population- and species-scale responses to climate forcing. PMID:25133631

Habitat suitability index model for brook trout in streams of the Southern Blue Ridge Province: surrogate variables, model evaluation, and suggested improvements

Treesearch

Christoper J. Schmitt; A. Dennis Lemly; Parley V. Winger

1993-01-01

Data from several sources were collated and analyzed by correlation, regression, and principal components analysis to define surrrogate variables for use in the brook trout (Salvelinus fontinalis) habitat suitability index (HSI) model, and to evaluate the applicability of the model for assessing habitat in high elevation streams of the southern Blue Ridge Province (...

Analysis of Social Variables when an Initial Functional Analysis Indicates Automatic Reinforcement as the Maintaining Variable for Self-Injurious Behavior

ERIC Educational Resources Information Center

Kuhn, Stephanie A. Contrucci; Triggs, Mandy

2009-01-01

Self-injurious behavior (SIB) that occurs at high rates across all conditions of a functional analysis can suggest automatic or multiple functions. In the current study, we conducted a functional analysis for 1 individual with SIB. Results indicated that SIB was, at least in part, maintained by automatic reinforcement. Further analyses using…

Dyadic variability in mother-adolescent interactions: developmental trajectories and associations with psychosocial functioning.

PubMed

Van der Giessen, Daniёlle; Branje, Susan J T; Frijns, Tom; Meeus, Wim H J

2013-01-01

Dyadic variability is considered to be a key mechanism in the development of mother-adolescent relationships, and low levels of dyadic flexibility are thought to be associated with behavior and relationship problems. The present observational study examined heterogeneity in the development of dyadic variability in mother-adolescent interactions and associations with psychosocial functioning. Dyadic variability refers to the range of emotional states during interactions of mother-adolescent dyads. During five annual home visits, 92 mother-adolescent dyads (M age T1 = 13; 65.2 % boys) were videotaped while discussing a conflict, and they completed several questionnaires on adolescents' aggressive behavior and adolescents' and mothers' perceived relationship quality. Two types of dyads were distinguished: low variability dyads (52 %) and high decreasing variability dyads (48 %). Over time, high decreasing variability dyads were characterized by a broader emotional repertoire than low variability dyads. Moreover, these two dyad types had distinct developmental patterns of psychosocial adjustment. Over time, high decreasing variability dyads showed lower levels of adolescents' aggressive behavior, and higher levels of perceived relationship quality than low variability dyads. These findings suggest that over time more dyadic variability is associated with less adjustment problems and a more constructive development of the mother-adolescent relationship. Adaptive interactions seem to be characterized by a wider range of emotional states and mothers should guide adolescents during interactions to express both positive and negative affect. Observing the dyadic variability during mother-adolescent interactions can help clinicians to distinguish adaptive from maladaptive mother-adolescent dyads.

The antigenic evolution of influenza: drift or thrift?

PubMed Central

Wikramaratna, Paul S.; Sandeman, Michi; Recker, Mario; Gupta, Sunetra

2013-01-01

It is commonly assumed that antibody responses against the influenza virus are polarized in the following manner: strong antibody responses are directed at highly variable antigenic epitopes, which consequently undergo ‘antigenic drift’, while weak antibody responses develop against conserved epitopes. As the highly variable epitopes are in a constant state of flux, current antibody-based vaccine strategies are focused on the conserved epitopes in the expectation that they will provide some level of clinical protection after appropriate boosting. Here, we use a theoretical model to suggest the existence of epitopes of low variability, which elicit a high degree of both clinical and transmission-blocking immunity. We show that several epidemiological features of influenza and its serological and molecular profiles are consistent with this model of ‘antigenic thrift’, and that identifying the protective epitopes of low variability predicted by this model could offer a more viable alternative to regularly update the influenza vaccine than exploiting responses to weakly immunogenic conserved regions. PMID:23382423

Paleoecology and high-resolution paleohydrology of a kettle peatland in upper Michigan

NASA Astrophysics Data System (ADS)

Booth, Robert K.; Jackson, Stephen T.; Gray, Catherine E. D.

2004-01-01

We investigated the developmental and hydrological history of a Sphagnum-dominated, kettle peatland in Upper Michigan using testate amoebae, plant macrofossils, and pollen. Our primary objective was to determine if the paleohydrological record of the peatland represents a record of past climate variability at subcentennial to millennial time scales. To assess the role of millennial-scale climate variability on peatland paleohydrology, we compared the timing of peatland and upland vegetation changes. To investigate the role of higher-frequency climate variability on peatland paleohydrology, we used testate amoebae to reconstruct a high-resolution, hydrologic history of the peatland for the past 5100 years, and compared this record to other regional records of paleoclimate and vegetation. Comparisons revealed coherent patterns of hydrological, vegetational, and climatic changes, suggesting that peatland paleohydrology responded to climate variability at millennial to sub-centennial time scales. Although ombrotrophic peatlands have been the focus of most high-resolution peatland paleoclimate research, paleohydrological records from Sphagnum-dominated, closed-basin peatlands record high-frequency and low-magnitude climatic changes and thus represent a significant source of unexplored paleoclimate data.

High resolution modeling in urban hydrology: comparison between two modeling approaches and their sensitivity to high rainfall variability

NASA Astrophysics Data System (ADS)

Ichiba, Abdellah; Gires, Auguste; Tchiguirinskaia, Ioulia; Bompard, Philippe; Schertzer, Daniel

2015-04-01

Urban water management is becoming increasingly complex, due to the rapid increase of impervious areas, and the potential effects of climate change. The large amount of water generated in a very short period of time and the limited capacity of sewer systems increase the vulnerability of urban environments to flooding risk and make it necessary to implement specific devices in order to handle the volume of water generated. This complex situation in urban environments makes the use of hydrological models as well as the implementation of more accurate and reliable tools for flow and rainfall measurements essential for a good pluvial network management, the use of decision support tools such as real-time radar forecasting system, the developpement of general public communication and warning systems, and the implementation of management strategy participate on limiting the flood damages. The very high spatial variability characteristic of urban environments makes it necessary to integrate the variability of physical properties and precipitation at fine scales in modeling processes, suggesting a high resolution modeling approach. In this paper we suggest a comparison between two modeling approaches and their sensitivity to small-scale rainfall variability on a 2.15 km2 urban area located in the County of Val-de-Marne (South-East of Paris, France). The first model used in this study is CANOE, which is a semi-distributed model widely used in France by practitioners for urban hydrology and urban water management. Two configurations of this model are be used in this study, the first one integrate 9 sub-catchments with sizes range from (1ha to 76ha), in the second configuration, the spatial resolution of this model has been improved with 45 sub-catchments with sizes range from (1ha to 14ha), the aim is to see how the semi-distributed model resolution affects it sensitivity to rainfall variability. The second model is Multi-Hydro fully distributed model developed at the Ecole des Ponts ParisTech. It is an interacting core between open source software packages, each of them representing a portion of the water cycle in urban environment. Multi-Hydro has been set up at two resolutions, 10m and 5m. The validation of these two models is performed using 5 rainfall events that occurred between 2010 and 2013. Radar data comes from the Météo-France radar mosaic and the resolution is 1 km in space and 5 min in time. Raingauge and flow measurements data comes from the General Council of Val-de-Marne County. In this validation part, the hydrological responses given by two models and the different configurations are compared to flow measurements. It appears that CANOE gives better results than Multi-Hydro model, especially when using raingauge data. For some events, we noticed that model responses given when using raingauge and radar data are different, suggesting a sign of sensitivity to the spatial variability of rainfall. 10 high-resolution rainfall events are used in the second part to study the sensitivity of each modeling approach to high rainfall variability. Radar data was available at four spatial resolutions (100, 200, 500 and 1000m) and two temporal resolutions (1min and 5min), for each event, two rainfall directions (parallel and perpendicular) are used, meaning that 16 hydrological responses are simulated for each event and the variability within it analyzed. First results suggest that the fully distributed model is more sensitive to high rainfall variability than the semi-distributed one, the increase of both hydrological model spatial resolution improves their sensitivity to rainfall variability. This study highlights some technical challenges facing the high-resolution modeling, especially the difficulty to obtain reliable input data at an acceptable resolution and also the high computation time noticed particularly for the semi-distributed model making it difficult to use it in real time. The authors greatly acknowledge partial financial support from the project RainGain (http://www.raingain.eu) of the EU Interreg program.

Using hypnosis to disrupt face processing: mirrored-self misidentification delusion and different visual media

PubMed Central

Connors, Michael H.; Barnier, Amanda J.; Coltheart, Max; Langdon, Robyn; Cox, Rochelle E.; Rivolta, Davide; Halligan, Peter W.

2014-01-01

Mirrored-self misidentification delusion is the belief that one’s reflection in the mirror is not oneself. This experiment used hypnotic suggestion to impair normal face processing in healthy participants and recreate key aspects of the delusion in the laboratory. From a pool of 439 participants, 22 high hypnotisable participants (“highs”) and 20 low hypnotisable participants were selected on the basis of their extreme scores on two separately administered measures of hypnotisability. These participants received a hypnotic induction and a suggestion for either impaired (i) self-face recognition or (ii) impaired recognition of all faces. Participants were tested on their ability to recognize themselves in a mirror and other visual media – including a photograph, live video, and handheld mirror – and their ability to recognize other people, including the experimenter and famous faces. Both suggestions produced impaired self-face recognition and recreated key aspects of the delusion in highs. However, only the suggestion for impaired other-face recognition disrupted recognition of other faces, albeit in a minority of highs. The findings confirm that hypnotic suggestion can disrupt face processing and recreate features of mirrored-self misidentification. The variability seen in participants’ responses also corresponds to the heterogeneity seen in clinical patients. An important direction for future research will be to examine sources of this variability within both clinical patients and the hypnotic model. PMID:24994973

Persistent millennial-scale link between Greenland climate and northern Pacific Oxygen Minimum Zone under interglacial conditions

NASA Astrophysics Data System (ADS)

Cartapanis, O.; Tachikawa, K.; Romero, O. E.; Bard, E.

2014-02-01

The intensity and/or extent of the northeastern Pacific Oxygen Minimum Zone (OMZ) varied in-phase with the Northern Hemisphere high latitude climate on millennial timescales during the last glacial period, indicating the occurrence of atmospheric and oceanic connections under glacial conditions. While millennial variability was reported for both the Greenland and the northern Atlantic Ocean during the last interglacial period, the climatic connections with the northeastern Pacific OMZ has not yet been observed under warm interglacial conditions. Here we present a new geochemical dataset, spanning the past 120 ka, for major components (terrigenous fraction, marine organic matter, biogenic opal, and carbonates) generated by X-ray fluorescence scanning alongside with biological productivity and redox sensitive trace element content (Mo, Ni, Cd) of sediment core MD02-2508 at 23° N, retrieved from the northern limit of the modern OMZ. Based on elemental ratios Si / Ti (proxy for opal), Cd / Al and Ni / Al, we suggest that biological productivity was high during the last interglacial (MIS5). Highly resolved opal reconstruction presents millennial variability corresponding to all the Dansgaard-Oeschger interstadial events over the last interglacial, while the Mo / Al ratio indicates reduced oxygenation during these events. Extremely high opal content during warm interstadials suggests high diatom productivity. Despite the different climatic and oceanic background between glacial and interglacial periods, rapid variability in the northeastern Pacific OMZ seems to be tightly related to Northern Hemisphere high latitude climate via atmospheric and possibly oceanic processes.

Antisaccade performance of 1,273 men: effects of schizotypy, anxiety, and depression.

PubMed

Smyrnis, Nikolaos; Evdokimidis, Ioannis; Stefanis, Nicholas C; Avramopoulos, Dimitrios; Constantinidis, Theodoros S; Stavropoulos, Alexios; Stefanis, Costas N

2003-08-01

A total of 1,273 conscripts of the Greek Air Force performed antisaccades and completed self-reporting questionnaires measuring schizotypy and current state-dependent psychopathology. Only 1.0% of variability in antisaccade performance indices was related to psychometric scores in the population and could be attributed more to current state-dependent symptoms such as anxiety rather than to schizotypy. In contrast, a specific increase of error rate and response latency variability and a high correlation of these 2 variables was observed in a group with very high schizotypy scores. This effect was independent of anxiety and depression, suggesting that a specific group of psychosis-prone individuals has a characteristic deviance in antisaccade performance that is not present in the general population.

Genetics of the Shimokita macaque population suggest an ancient bottleneck.

PubMed

Kawamoto, Yoshi; Tomari, Ken-ichiro; Kawai, Shizuka; Kawamoto, Sakie

2008-01-01

The macaque population of the Shimokita Peninsula represents the northernmost distribution of this species and is isolated from other populations in the Tohoku region of Japan. A previous protein-based study revealed a high level of genetic variability in this population and considerable differentiation from other populations. In order to reassess the genetic features of the Shimokita macaques, we examined 11 autosomal microsatellite loci and three Y chromosomal microsatellite loci. We observed considerable differentiation from other Japanese populations of macaques, but in contrast to the previous results, we observed significantly lower genetic variability in this population. There was a weak indication of a population bottleneck, suggesting a decay over time from an excess of heterozygotes that might be expected in the initial stages of a bottleneck. This may indicate that an ancient bottleneck occurred during the warm period after the last glacial period rather than a recent bottleneck due to hunting in modern times. The frequencies of private alleles were exceptionally high in the Shimokita population, suggesting that the difference in variability as determined in various studies was due to accidental sampling of marker loci with low power to resolve genetic variations in the protein-based studies. The assessments of interpopulation differentiation as determined using autosomal and Y chromosomal markers were highly correlated, and using both types of markers the Shimokita population was found to be the most differentiated of the study populations, probably due to infrequent gene flow with surrounding populations.

Poor phonetic perceivers are affected by cognitive load when resolving talker variability

PubMed Central

Antoniou, Mark; Wong, Patrick C. M.

2015-01-01

Speech training paradigms aim to maximise learning outcomes by manipulating external factors such as talker variability. However, not all individuals may benefit from such manipulations because subject-external factors interact with subject-internal ones (e.g., aptitude) to determine speech perception and/or learning success. In a previous tone learning study, high-aptitude individuals benefitted from talker variability, whereas low-aptitude individuals were impaired. Because increases in cognitive load have been shown to hinder speech perception in mixed-talker conditions, it has been proposed that resolving talker variability requires cognitive resources. This proposal leads to the hypothesis that low-aptitude individuals do not use their cognitive resources as efficiently as those with high aptitude. Here, high- and low-aptitude subjects identified pitch contours spoken by multiple talkers under high and low cognitive load conditions established by a secondary task. While high-aptitude listeners outperformed low-aptitude listeners across load conditions, only low-aptitude listeners were impaired by increased cognitive load. The findings suggest that low-aptitude listeners either have fewer available cognitive resources or are poorer at allocating attention to the signal. Therefore, cognitive load is an important factor when considering individual differences in speech perception and training paradigms. PMID:26328675

Poor phonetic perceivers are affected by cognitive load when resolving talker variability.

PubMed

Antoniou, Mark; Wong, Patrick C M

2015-08-01

Speech training paradigms aim to maximise learning outcomes by manipulating external factors such as talker variability. However, not all individuals may benefit from such manipulations because subject-external factors interact with subject-internal ones (e.g., aptitude) to determine speech perception and/or learning success. In a previous tone learning study, high-aptitude individuals benefitted from talker variability, whereas low-aptitude individuals were impaired. Because increases in cognitive load have been shown to hinder speech perception in mixed-talker conditions, it has been proposed that resolving talker variability requires cognitive resources. This proposal leads to the hypothesis that low-aptitude individuals do not use their cognitive resources as efficiently as those with high aptitude. Here, high- and low-aptitude subjects identified pitch contours spoken by multiple talkers under high and low cognitive load conditions established by a secondary task. While high-aptitude listeners outperformed low-aptitude listeners across load conditions, only low-aptitude listeners were impaired by increased cognitive load. The findings suggest that low-aptitude listeners either have fewer available cognitive resources or are poorer at allocating attention to the signal. Therefore, cognitive load is an important factor when considering individual differences in speech perception and training paradigms.

Basinwide response of the Atlantic Meridional Overturning Circulation to interannual wind forcing

NASA Astrophysics Data System (ADS)

Zhao, Jian

2017-12-01

An eddy-resolving Ocean general circulation model For the Earth Simulator (OFES) and a simple wind-driven two-layer model are used to investigate the role of momentum fluxes in driving the Atlantic Meridional Overturning Circulation (AMOC) variability throughout the Atlantic basin from 1950 to 2010. Diagnostic analysis using the OFES results suggests that interior baroclinic Rossby waves and coastal topographic waves play essential roles in modulating the AMOC interannual variability. The proposed mechanisms are verified in the context of a simple two-layer model with realistic topography and only forced by surface wind. The topographic waves communicate high-latitude anomalies into lower latitudes and account for about 50% of the AMOC interannual variability in the subtropics. In addition, the large scale Rossby waves excited by wind forcing together with topographic waves set up coherent AMOC interannual variability patterns across the tropics and subtropics. The comparisons between the simple model and OFES results suggest that a large fraction of the AMOC interannual variability in the Atlantic basin can be explained by wind-driven dynamics.

A mouse model of high trait anxiety shows reduced heart rate variability that can be reversed by anxiolytic drug treatment.

PubMed

Gaburro, Stefano; Stiedl, Oliver; Giusti, Pietro; Sartori, Simone B; Landgraf, Rainer; Singewald, Nicolas

2011-11-01

Increasing evidence suggests that specific physiological measures may serve as biomarkers for successful treatment to alleviate symptoms of pathological anxiety. Studies of autonomic function investigating parameters such as heart rate (HR), HR variability and blood pressure (BP) indicated that HR variability is consistently reduced in anxious patients, whereas HR and BP data show inconsistent results. Therefore, HR and HR variability were measured under various emotionally challenging conditions in a mouse model of high innate anxiety (high anxiety behaviour; HAB) vs. control normal anxiety-like behaviour (NAB) mice. Baseline HR, HR variability and activity did not differ between mouse lines. However, after cued Pavlovian fear conditioning, both elevated tachycardia and increased fear responses were observed in HAB mice compared to NAB mice upon re-exposure to the conditioning stimulus serving as the emotional stressor. When retention of conditioned fear was tested in the home cage, HAB mice again displayed higher fear responses than NAB mice, while the HR responses were similar. Conversely, in both experimental settings HAB mice consistently exhibited reduced HR variability. Repeated administration of the anxiolytic NK1 receptor antagonist L-822429 lowered the conditioned fear response and shifted HR dynamics in HAB mice to a more regular pattern, similar to that in NAB mice. Additional receiver-operating characteristic (ROC) analysis demonstrated the high specificity and sensitivity of HR variability to distinguish between normal and high anxiety trait. These findings indicate that assessment of autonomic response in addition to freezing might be a useful indicator of the efficacy of novel anxiolytic treatments.

An Exploratory Study of the Influence of Load and Practice on Segmental and Articulatory Variability in Children with Speech Sound Disorders

PubMed Central

Vuolo, Janet; Goffman, Lisa

2017-01-01

This exploratory treatment study used phonetic transcription and speech kinematics to examine changes in segmental and articulatory variability. Nine children, ages 4- to 8-years-old, served as participants, including two with childhood apraxia of speech (CAS), five with speech sound disorder (SSD), and two who were typically developing (TD). Children practised producing agent + action phrases in an imitation task (low linguistic load) and a retrieval task (high linguistic load) over five sessions. In the imitation task in session one, both participants with CAS showed high degrees of segmental and articulatory variability. After five sessions, imitation practice resulted in increased articulatory variability for five participants. Retrieval practice resulted in decreased articulatory variability in three participants with SSD. These results suggest that short-term speech production practice in rote imitation disrupts articulatory control in children with and without CAS. In contrast, tasks that require linguistic processing may scaffold learning for children with SSD but not CAS. PMID:27960554

Analysis of Intra- and Intersubject Variability in Oral Drug Absorption in Human Bioequivalence Studies of 113 Generic Products.

PubMed

Sugihara, Masahisa; Takeuchi, Susumu; Sugita, Masaru; Higaki, Kazutaka; Kataoka, Makoto; Yamashita, Shinji

2015-12-07

In this study, the data of 113 human bioequivalence (BE) studies of immediate release (IR) formulations of 74 active pharmaceutical ingredients (APIs) conducted at Sawai Pharmaceutical Co., Ltd., was analyzed to understand the factors affecting intra- and intersubject variabilities in oral drug absorption. The ANOVA CV (%) calculated from area under the time-concentration curve (AUC) in each BE study was used as an index of intrasubject variability (Vintra), and the relative standard deviation (%) in AUC was used as that of intersubject variability (Vinter). Although no significant correlation was observed between Vintra and Vinter of all drugs, Vintra of class 3 drugs was found to increase in association with a decrease in drug permeability (P(eff)). Since the absorption of class 3 drugs was rate-limited by the permeability, it was suggested that, for such drugs, the low P(eff) might be a risk factor to cause a large intrasubject variability. To consider the impact of poor water solubility on the variability in BE study, a parameter of P(eff)/Do (Do; dose number) was defined to discriminate the solubility-limited and dissolution-rate-limited absorption of class 2 drugs. It was found that the class 2 drugs with a solubility-limited absorption (P(eff)/Do < 0.149 × 10(-4) cm/s) showed high intrasubject variability. Furthermore, as a reason for high intra- or intersubject variability in AUC for class 1 drugs, effects of drug metabolizing enzymes were investigated. It was demonstrated that intrasubject variability was high for drugs metabolized by CYP3A4 while intersubject variability was high for drugs metabolized by CYP2D6. For CYP3A4 substrate drugs, the Km value showed the significant relation with Vintra, indicating that the affinity to the enzyme can be a parameter to predict the risk of high intrasubject variability. In conclusion, by analyzing the in house data of human BE study, low permeability, solubility-limited absorption, and high affinity to CYP3A4 are identified as risk factors for high intrasubject variability in oral drug absorption. This information is of importance to design the human BE study for oral drug products containing APIs with a risk of large intrasubject variability in oral absorption.

Temporal analysis of the frequency and duration of low and high streamflow: Years of record needed to characterize streamflow variability

USGS Publications Warehouse

Huh, S.; Dickey, D.A.; Meador, M.R.; Ruhl, K.E.

2005-01-01

A temporal analysis of the number and duration of exceedences of high- and low-flow thresholds was conducted to determine the number of years required to detect a level shift using data from Virginia, North Carolina, and South Carolina. Two methods were used - ordinary least squares assuming a known error variance and generalized least squares without a known error variance. Using ordinary least squares, the mean number of years required to detect a one standard deviation level shift in measures of low-flow variability was 57.2 (28.6 on either side of the break), compared to 40.0 years for measures of high-flow variability. These means become 57.6 and 41.6 when generalized least squares is used. No significant relations between years and elevation or drainage area were detected (P>0.05). Cluster analysis did not suggest geographic patterns in years related to physiography or major hydrologic regions. Referring to the number of observations required to detect a one standard deviation shift as 'characterizing' the variability, it appears that at least 20 years of record on either side of a shift may be necessary to adequately characterize high-flow variability. A longer streamflow record (about 30 years on either side) may be required to characterize low-flow variability. ?? 2005 Elsevier B.V. All rights reserved.

Effect of breakfast on selected serum and cardiovascular variables

NASA Technical Reports Server (NTRS)

Frey, Mary A. B.; Merz, Marion P.; Hoffler, G. W.

1992-01-01

In view of the objections of many subjects to overnight fasting prior to their blood being drawn for analyses, the effect of eating breakfast on the results of subsequent blood analyses of selected blood constituents and on cardiovascular variables was investigated in 47 men and 34 women who were subjected to blood analyses on two occasions, one week apart: once fasting and once after breakfast. Results suggest that subjects need not fast overnight before blood is being drawn for determinations of the HDL-C levels, hemoglobin, hematocrit, total cholesterol, or phosphorus. However, based on other studies, it is suggested breakfast should not have a high content of fat.

GRMHD Simulations of Visibility Amplitude Variability for Event Horizon Telescope Images of Sgr A*

NASA Astrophysics Data System (ADS)

Medeiros, Lia; Chan, Chi-kwan; Özel, Feryal; Psaltis, Dimitrios; Kim, Junhan; Marrone, Daniel P.; Sa¸dowski, Aleksander

2018-04-01

The Event Horizon Telescope will generate horizon scale images of the black hole in the center of the Milky Way, Sgr A*. Image reconstruction using interferometric visibilities rests on the assumption of a stationary image. We explore the limitations of this assumption using high-cadence disk- and jet-dominated GRMHD simulations of Sgr A*. We also employ analytic models that capture the basic characteristics of the images to understand the origin of the variability in the simulated visibility amplitudes. We find that, in all simulations, the visibility amplitudes for baselines oriented parallel and perpendicular to the spin axis of the black hole follow general trends that do not depend strongly on accretion-flow properties. This suggests that fitting Event Horizon Telescope observations with simple geometric models may lead to a reasonably accurate determination of the orientation of the black hole on the plane of the sky. However, in the disk-dominated models, the locations and depths of the minima in the visibility amplitudes are highly variable and are not related simply to the size of the black hole shadow. This suggests that using time-independent models to infer additional black hole parameters, such as the shadow size or the spin magnitude, will be severely affected by the variability of the accretion flow.

Changes in heart rate variability are associated with expression of short-term and long-term contextual and cued fear memories.

PubMed

Liu, Jun; Wei, Wei; Kuang, Hui; Zhao, Fang; Tsien, Joe Z

2013-01-01

Heart physiology is a highly useful indicator for measuring not only physical states, but also emotional changes in animals. Yet changes of heart rate variability during fear conditioning have not been systematically studied in mice. Here, we investigated changes in heart rate and heart rate variability in both short-term and long-term contextual and cued fear conditioning. We found that while fear conditioning could increase heart rate, the most significant change was the reduction in heart rate variability which could be further divided into two distinct stages: a highly rhythmic phase (stage-I) and a more variable phase (stage-II). We showed that the time duration of the stage-I rhythmic phase were sensitive enough to reflect the transition from short-term to long-term fear memories. Moreover, it could also detect fear extinction effect during the repeated tone recall. These results suggest that heart rate variability is a valuable physiological indicator for sensitively measuring the consolidation and expression of fear memories in mice.

The role of CO2 variability and exposure time for biological impacts of ocean acidification

NASA Astrophysics Data System (ADS)

Shaw, Emily C.; Munday, Philip L.; McNeil, Ben I.

2013-09-01

impacts of ocean acidification have mostly been studied using future levels of CO2 without consideration of natural variability or how this modulates both duration and magnitude of CO2 exposure. Here we combine results from laboratory studies on coral reef fish with diurnal in situ CO2 data from a shallow coral reef, to demonstrate how natural variability alters exposure times for marine organisms under increasingly high-CO2 conditions. Large in situ CO2 variability already results in exposure of coral reef fish to short-term CO2 levels higher than laboratory-derived critical CO2 levels (~600 µatm). However, we suggest that the in situ exposure time is presently insufficient to induce negative effects observed in laboratory studies. Our results suggest that both exposure time and the magnitude of CO2 levels will be important in determining the response of organisms to future ocean acidification, where both will increase markedly with future increases in CO2.

The Influence of Individual Variability on Zooplankton Population Dynamics under Different Environmental Conditions

NASA Astrophysics Data System (ADS)

Bi, R.; Liu, H.

2016-02-01

Understanding how biological components respond to environmental changes could be insightful to predict ecosystem trajectories under different climate scenarios. Zooplankton are key components of marine ecosystems and changes in their dynamics could have major impact on ecosystem structure. We developed an individual-based model of a common coastal calanoid copepod Acartia tonsa to examine how environmental factors affect zooplankton population dynamics and explore the role of individual variability in sustaining population under various environmental conditions consisting of temperature, food concentration and salinity. Total abundance, egg production and proportion of survival were used to measure population success. Results suggested population benefits from high level of individual variability under extreme environmental conditions including unfavorable temperature, salinity, as well as low food concentration, and selection on fast-growers becomes stronger with increasing individual variability and increasing environmental stress. Multiple regression analysis showed that temperature, food concentration, salinity and individual variability have significant effects on survival of A. tonsa population. These results suggest that environmental factors have great influence on zooplankton population, and individual variability has important implications for population survivability under unfavorable conditions. Given that marine ecosystems are at risk from drastic environmental changes, understanding how individual variability sustains populations could increase our capability to predict population dynamics in a changing environment.

Characterization of the Infrared/X-ray sub-second variability for the black-hole transient GX 339-4

NASA Astrophysics Data System (ADS)

Vincentelli, F. M.; Casella, P.; Maccarone, T. J.; Uttley, P.; Gandhi, P.; Belloni, T.; De Marco, B.; Russell, D. M.; Stella, L.; O'Brien, K.

2018-03-01

We present a detailed analysis of the X-ray/IR fast variability of the Black-Hole Transient GX 339-4 during its low/hard state in August 2008. Thanks to simultaneous high time-resolution observations made with the VLT and RXTE, we performed the first characterisation of the sub-second variability in the near-infrared band - and of its correlation with the X-rays - for a low-mass X-ray binary, using both time- and frequency-domain techniques. We found a power-law correlation between the X-ray and infrared fluxes when measured on timescales of 16 seconds, with a marginally variable slope, steeper than the one found on timescales of days at similar flux levels. We suggest the variable slope - if confirmed - could be due to the infrared flux being a non-constant combination of both optically thin and optically thick synchrotron emission from the jet, as a result of a variable self-absorption break. From cross spectral analysis we found an approximately constant infrared time lag of ≈0.1s, and a very high coherence of ˜90 per cent on timescales of tens of seconds, slowly decreasing toward higher frequencies. Finally, we report on the first detection of a linear rms-flux relation in the emission from a low-mass X-ray binary jet, on timescales where little correlation is found between the X-rays and the jet emission itself. This suggests that either the inflow variations and jet IR emission are coupled by a non-linear or time-variable transform, or that the IR rms-flux relation is not transferred from the inflow to the jet, but is an intrinsic property of emission processes in the jet.

Characterization of the infrared/X-ray subsecond variability for the black hole transient GX 339-4

NASA Astrophysics Data System (ADS)

Vincentelli, F. M.; Casella, P.; Maccarone, T. J.; Uttley, P.; Gandhi, P.; Belloni, T.; De Marco, B.; Russell, D. M.; Stella, L.; O'Brien, K.

2018-07-01

We present a detailed analysis of the X-ray/IR fast variability of the Black-Hole Transient GX 339-4 during its low/hard state in 2008 August. Thanks to simultaneous high time resolution observations made with the VLT and RXTE, we performed the first characterization of the subsecond variability in the near-infrared band - and of its correlation with the X-rays - for a low-mass X-ray binary, using both time- and frequency-domain techniques. We found a power-law correlation between the X-ray and infrared fluxes when measured on time-scales of 16 s, with a marginally variable slope, steeper than the one found on time-scales of days at similar flux levels. We suggest the variable slope - if confirmed - could be due to the infrared flux being a non-constant combination of both optically thin and optically thick synchrotron emission from the jet, as a result of a variable self-absorption break. From cross spectral analysis, we found an approximately constant infrared time lag of ≈0.1 s, and a very high coherence of ˜90 per cent on time-scales of tens of seconds, slowly decreasing towards higher frequencies. Finally, we report on the first detection of a linear rms-flux relation in the emission from a low-mass X-ray binary jet, on time-scales where little correlation is found between the X-rays and the jet emission itself. This suggests that either the inflow variations and jet IR emission are coupled by a non-linear or time-variable transform, or that the IR rms-flux relation is not transferred from the inflow to the jet, but is an intrinsic property of emission processes in the jet.

Learning to combine high variability with high precision: lack of transfer to a different task.

PubMed

Wu, Yen-Hsun; Truglio, Thomas S; Zatsiorsky, Vladimir M; Latash, Mark L

2015-01-01

The authors studied effects of practicing a 4-finger accurate force production task on multifinger coordination quantified within the uncontrolled manifold hypothesis. During practice, task instability was modified by changing visual feedback gain based on accuracy of performance. The authors also explored the retention of these effects, and their transfer to a prehensile task. Subjects practiced the force production task for 2 days. After the practice, total force variability decreased and performance became more accurate. In contrast, variance of finger forces showed a tendency to increase during the first practice session while in the space of finger modes (hypothetical commands to fingers) the increase was under the significance level. These effects were retained for 2 weeks. No transfer of these effects to the prehensile task was seen, suggesting high specificity of coordination changes. The retention of practice effects without transfer to a different task suggests that further studies on a more practical method of improving coordination are needed.

Inter-individual cognitive variability in children with Asperger's syndrome

PubMed Central

Gonzalez-Gadea, Maria Luz; Tripicchio, Paula; Rattazzi, Alexia; Baez, Sandra; Marino, Julian; Roca, Maria; Manes, Facundo; Ibanez, Agustin

2014-01-01

Multiple studies have tried to establish the distinctive profile of individuals with Asperger's syndrome (AS). However, recent reports suggest that adults with AS feature heterogeneous cognitive profiles. The present study explores inter-individual variability in children with AS through group comparison and multiple case series analysis. All participants completed an extended battery including measures of fluid and crystallized intelligence, executive functions, theory of mind, and classical neuropsychological tests. Significant group differences were found in theory of mind and other domains related to global information processing. However, the AS group showed high inter-individual variability (both sub- and supra-normal performance) on most cognitive tasks. Furthermore, high fluid intelligence correlated with less general cognitive impairment, high cognitive flexibility, and speed of motor processing. In light of these findings, we propose that children with AS are characterized by a distinct, uneven pattern of cognitive strengths and weaknesses. PMID:25132817

Variations in brain defects result from cellular mosaicism in the activation of heat shock signalling.

PubMed

Ishii, Seiji; Torii, Masaaki; Son, Alexander I; Rajendraprasad, Meenu; Morozov, Yury M; Kawasawa, Yuka Imamura; Salzberg, Anna C; Fujimoto, Mitsuaki; Brennand, Kristen; Nakai, Akira; Mezger, Valerie; Gage, Fred H; Rakic, Pasko; Hashimoto-Torii, Kazue

2017-05-02

Repetitive prenatal exposure to identical or similar doses of harmful agents results in highly variable and unpredictable negative effects on fetal brain development ranging in severity from high to little or none. However, the molecular and cellular basis of this variability is not well understood. This study reports that exposure of mouse and human embryonic brain tissues to equal doses of harmful chemicals, such as ethanol, activates the primary stress response transcription factor heat shock factor 1 (Hsf1) in a highly variable and stochastic manner. While Hsf1 is essential for protecting the embryonic brain from environmental stress, excessive activation impairs critical developmental events such as neuronal migration. Our results suggest that mosaic activation of Hsf1 within the embryonic brain in response to prenatal environmental stress exposure may contribute to the resulting generation of phenotypic variations observed in complex congenital brain disorders.

Visit-to-visit and 24-h blood pressure variability: association with endothelial and smooth muscle function in African Americans.

PubMed

Diaz, K M; Veerabhadrappa, P; Kashem, M A; Thakkar, S R; Feairheller, D L; Sturgeon, K M; Ling, C; Williamson, S T; Kretzschmar, J; Lee, H; Grimm, H; Babbitt, D M; Vin, C; Fan, X; Crabbe, D L; Brown, M D

2013-11-01

The purpose of this study was to investigate the association of visit-to-visit and 24-h blood pressure (BP) variability with markers of endothelial injury and vascular function. We recruited 72 African Americans who were non-diabetic, non-smoking and free of cardiovascular (CV) and renal disease. Office BP was measured at three visits and 24-h ambulatory BP monitoring was conducted to measure visit-to-visit and 24-h BP variability, respectively. The 5-min time-course of brachial artery flow-mediated dilation and nitroglycerin-mediated dilation were assessed as measures of endothelial and smooth muscle function. Fasted blood samples were analyzed for circulating endothelial microparticles (EMPs). Significantly lower CD31+CD42- EMPs were found in participants with high visit-to-visit systolic blood pressure (SBP) variability or high 24-h diastolic blood pressure (DBP) variability. Participants with high visit-to-visit DBP variability had significantly lower flow-mediated dilation and higher nitroglycerin-mediated dilation at multiple time-points. When analyzed as continuous variables, 24-h mean arterial pressure variability was inversely associated with CD62+ EMPs; visit-to-visit DBP variability was inversely associated with flow-mediated dilation normalized by smooth muscle function and was positively associated with nitroglycerin-mediated dilation; and 24-h DBP variability was positively associated with nitroglycerin-mediated dilation. All associations were independent of age, gender, body mass index and mean BP. In conclusion, in this cohort of African Americans visit-to-visit and 24-h BP variability were associated with measures of endothelial injury, endothelial function and smooth muscle function. These results suggest that BP variability may influence the pathogenesis of CV disease, in part, through influences on vascular health.

Midlatitude atmospheric OH response to the most recent 11-y solar cycle.

PubMed

Wang, Shuhui; Li, King-Fai; Pongetti, Thomas J; Sander, Stanley P; Yung, Yuk L; Liang, Mao-Chang; Livesey, Nathaniel J; Santee, Michelle L; Harder, Jerald W; Snow, Martin; Mills, Franklin P

2013-02-05

The hydroxyl radical (OH) plays an important role in middle atmospheric photochemistry, particularly in ozone (O(3)) chemistry. Because it is mainly produced through photolysis and has a short chemical lifetime, OH is expected to show rapid responses to solar forcing [e.g., the 11-y solar cycle (SC)], resulting in variabilities in related middle atmospheric O(3) chemistry. Here, we present an effort to investigate such OH variability using long-term observations (from space and the surface) and model simulations. Ground-based measurements and data from the Microwave Limb Sounder on the National Aeronautics and Space Administration's Aura satellite suggest an ∼7-10% decrease in OH column abundance from solar maximum to solar minimum that is highly correlated with changes in total solar irradiance, solar Mg-II index, and Lyman-α index during SC 23. However, model simulations using a commonly accepted solar UV variability parameterization give much smaller OH variability (∼3%). Although this discrepancy could result partially from the limitations in our current understanding of middle atmospheric chemistry, recently published solar spectral irradiance data from the Solar Radiation and Climate Experiment suggest a solar UV variability that is much larger than previously believed. With a solar forcing derived from the Solar Radiation and Climate Experiment data, modeled OH variability (∼6-7%) agrees much better with observations. Model simulations reveal the detailed chemical mechanisms, suggesting that such OH variability and the corresponding catalytic chemistry may dominate the O(3) SC signal in the upper stratosphere. Continuing measurements through SC 24 are required to understand this OH variability and its impacts on O(3) further.

Midlatitude atmospheric OH response to the most recent 11-y solar cycle

PubMed Central

Wang, Shuhui; Li, King-Fai; Pongetti, Thomas J.; Sander, Stanley P.; Yung, Yuk L.; Liang, Mao-Chang; Livesey, Nathaniel J.; Santee, Michelle L.; Harder, Jerald W.; Snow, Martin; Mills, Franklin P.

2013-01-01

The hydroxyl radical (OH) plays an important role in middle atmospheric photochemistry, particularly in ozone (O3) chemistry. Because it is mainly produced through photolysis and has a short chemical lifetime, OH is expected to show rapid responses to solar forcing [e.g., the 11-y solar cycle (SC)], resulting in variabilities in related middle atmospheric O3 chemistry. Here, we present an effort to investigate such OH variability using long-term observations (from space and the surface) and model simulations. Ground-based measurements and data from the Microwave Limb Sounder on the National Aeronautics and Space Administration’s Aura satellite suggest an ∼7–10% decrease in OH column abundance from solar maximum to solar minimum that is highly correlated with changes in total solar irradiance, solar Mg-II index, and Lyman-α index during SC 23. However, model simulations using a commonly accepted solar UV variability parameterization give much smaller OH variability (∼3%). Although this discrepancy could result partially from the limitations in our current understanding of middle atmospheric chemistry, recently published solar spectral irradiance data from the Solar Radiation and Climate Experiment suggest a solar UV variability that is much larger than previously believed. With a solar forcing derived from the Solar Radiation and Climate Experiment data, modeled OH variability (∼6–7%) agrees much better with observations. Model simulations reveal the detailed chemical mechanisms, suggesting that such OH variability and the corresponding catalytic chemistry may dominate the O3 SC signal in the upper stratosphere. Continuing measurements through SC 24 are required to understand this OH variability and its impacts on O3 further. PMID:23341617

Southern Hemisphere climate variability forced by Northern Hemisphere ice-sheet topography

NASA Astrophysics Data System (ADS)

Jones, T. R.; Roberts, W. H. G.; Steig, E. J.; Cuffey, K. M.; Markle, B. R.; White, J. W. C.

2018-02-01

The presence of large Northern Hemisphere ice sheets and reduced greenhouse gas concentrations during the Last Glacial Maximum fundamentally altered global ocean-atmosphere climate dynamics. Model simulations and palaeoclimate records suggest that glacial boundary conditions affected the El Niño-Southern Oscillation, a dominant source of short-term global climate variability. Yet little is known about changes in short-term climate variability at mid- to high latitudes. Here we use a high-resolution water isotope record from West Antarctica to demonstrate that interannual to decadal climate variability at high southern latitudes was almost twice as large at the Last Glacial Maximum as during the ensuing Holocene epoch (the past 11,700 years). Climate model simulations indicate that this increased variability reflects an increase in the teleconnection strength between the tropical Pacific and West Antarctica, owing to a shift in the mean location of tropical convection. This shift, in turn, can be attributed to the influence of topography and albedo of the North American ice sheets on atmospheric circulation. As the planet deglaciated, the largest and most abrupt decline in teleconnection strength occurred between approximately 16,000 years and 15,000 years ago, followed by a slower decline into the early Holocene.

OBSERVING CORONAL NANOFLARES IN ACTIVE REGION MOSS

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

Testa, Paola; DeLuca, Ed; Golub, Leon

2013-06-10

The High-resolution Coronal Imager (Hi-C) has provided Fe XII 193A images of the upper transition region moss at an unprecedented spatial ({approx}0.''3-0.''4) and temporal (5.5 s) resolution. The Hi-C observations show in some moss regions variability on timescales down to {approx}15 s, significantly shorter than the minute-scale variability typically found in previous observations of moss, therefore challenging the conclusion of moss being heated in a mostly steady manner. These rapid variability moss regions are located at the footpoints of bright hot coronal loops observed by the Solar Dynamics Observatory/Atmospheric Imaging Assembly in the 94 A channel, and by the Hinode/X-Raymore » Telescope. The configuration of these loops is highly dynamic, and suggestive of slipping reconnection. We interpret these events as signatures of heating events associated with reconnection occurring in the overlying hot coronal loops, i.e., coronal nanoflares. We estimate the order of magnitude of the energy in these events to be of at least a few 10{sup 23} erg, also supporting the nanoflare scenario. These Hi-C observations suggest that future observations at comparable high spatial and temporal resolution, with more extensive temperature coverage, are required to determine the exact characteristics of the heating mechanism(s).« less

Fear of humans and its relationships with productivity in laying hens at commercial farms.

PubMed

Barnett, J L; Hemsworth, P H; Newman, E A

1992-09-01

1. The relationship between the behavioural responses of laying hens to humans and productivity was determined at 16 commercial sheds from 14 farms. 2. A number of behaviour variables were moderately to highly correlated with production variables; for example, the proportion of birds that moved away from an approaching experimenter in an unfamiliar environment ('shute test') was negatively correlated with peak hen day production, (PKHDP). 3. Behavioural responses to humans accounted for between 23 and 63% of the variation in a number of production variables, including PKHDP and the duration of a high level of production. 4. Inclusion of farm factor variables increased the amount of variation accounted for by the behaviour variables. For example, adding the variable 'time/day spent in the shed by stockpeople' to the behaviour variables 'the proportion of birds that moved away from an approaching human' in the shute test and 'the number of times birds in cages adopted an erect posture' in response to an approaching human increased the variation accounted for in PKHDP from 53 to 61%. 5. The results suggest that fear of humans may be a factor that limits the productivity of commercial laying hens.

Career Indecision in Adult Women: A Comparative and Descriptive Study.

ERIC Educational Resources Information Center

Slaney, Robert B.; And Others

1981-01-01

Compared high-school women, first-year college women, and adult women on four measures of career indecision. Results suggested that the adult women were experiencing more career indecision than the high-school and college women. Variables included: marital status, present work experience, the career-related goals and possible impediments to…

Research into Factors Contributing to Discipline Use and Disproportionality in Major Urban Schools

ERIC Educational Resources Information Center

Mcloughlin, Caven S.; Noltemeyer, Amity L.

2010-01-01

Compared to other school typologies, major urban high poverty schools more frequently use exclusionary discipline and apply these techniques disproportionately to African American students. We explored school demographic variables predicting these two outcomes using data from 440 major urban, high poverty schools. Results suggest a different set…

Proactive vs. reactive car driving: EEG evidence for different driving strategies of older drivers

PubMed Central

Wascher, Edmund; Getzmann, Stephan

2018-01-01

Aging is associated with a large heterogeneity in the extent of age-related changes in sensory, motor, and cognitive functions. All these functions can influence the performance in complex tasks like car driving. The present study aims to identify potential differences in underlying cognitive processes that may explain inter-individual variability in driving performance. Younger and older participants performed a one-hour monotonous driving task in a driving simulator under varying crosswind conditions, while behavioral and electrophysiological data were recorded. Overall, younger and older drivers showed comparable driving performance (lane keeping). However, there was a large difference in driving lane variability within the older group. Dividing the older group in two subgroups with low vs. high driving lane variability revealed differences between the two groups in electrophysiological correlates of mental workload, consumption of mental resources, and activation and sustaining of attention: Older drivers with high driving lane variability showed higher frontal Alpha and Theta activity than older drivers with low driving lane variability and—with increasing crosswind—a more pronounced decrease in Beta activity. These results suggest differences in driving strategies of older and younger drivers, with the older drivers using either a rather proactive and alert driving strategy (indicated by low driving lane variability and lower Alpha and Beta activity), or a rather reactive strategy (indicated by high driving lane variability and higher Alpha activity). PMID:29352314

Serosurvey of selected viruses in captive giant pandas (Ailuropoda melanoleuca) in China.

PubMed

Qin, Qin; Li, Desheng; Zhang, Hemin; Hou, Rong; Zhang, Zhihe; Zhang, Chenglin; Zhang, Jinguo; Wei, Fuwen

2010-05-19

Serum samples from 92 giant pandas in three captive facilities were tested for antibodies against five viruses of carnivores. Antibody titers against canine distemper virus (CDV) in two facilities in which giant pandas were vaccinated were variable. The canine adenovirus (CAV-1) and canine parvovirus (CPV) titers in vaccinated group were both positive, but titers were not high and varied among individual except one vaccinated panda had extremely high CAV-1 titer, indicating infection with the field virus following vaccination. Our results suggest that the vaccines used for these giant pandas do not elicit consistent antibody titers. Antibody titers against CDV, CPV and CAV-1 in unvaccinated giant pandas were highly variable, especially CPV titer. Almost half of sera were CPV antibody positive, and CPV titers were high enough to suggest infection with the virus. Canine coronavirus (CCV) and canine parainfluenza virus (CPIV) titers were not detected in all serum samples. The results of this study emphasize the need for research on infectious diseases of giant pandas and development of suitable vaccines for the species. Copyright 2009 Elsevier B.V. All rights reserved.

Heart rate variability is associated with social value orientation in males but not females.

PubMed

Lischke, Alexander; Mau-Moeller, Anett; Jacksteit, Robert; Pahnke, Rike; Hamm, Alfons O; Weippert, Matthias

2018-05-09

Phylogenetic and neurobiological theories suggest that inter-individual differences in high frequency heart rate variability (HF-HRV) are associated with inter-individual differences in social behavior and social cognition. To test these theories, we investigated whether individuals with high and low HF-HRV would show different preferences for cooperative behavior in social contexts. We recorded resting state HF-HRV in 84 healthy individuals before they completed the Social Value Orientation task, a well-established measure of cooperative preferences. HF-HRV was derived from short-term (300 s) and ultra-short-term (60 s, 120 s) recordings of participants' heart rate to determine the robustness of possible findings. Irrespective of recording length, we found a sex-dependent association between inter-individual differences in HF-HRV and inter-individual differences in social value orientation: The preference for cooperation was more pronounced among individuals with high as compared low HF-HRV, albeit only in male and not in female participants. These findings suggest that males with high HF-HRV are more inclined to engage in cooperative behavior than males with low HF-HRV.

North Atlantic sub-decadal variability in climate models

NASA Astrophysics Data System (ADS)

Reintges, Annika; Martin, Thomas; Latif, Mojib; Park, Wonsun

2017-04-01

The North Atlantic Oscillation (NAO) is the dominant variability mode for the winter climate of the North Atlantic sector. During a positive (negative) NAO phase, the sea level pressure (SLP) difference between the subtropical Azores high and the subpolar Icelandic low is anomalously strong (weak). This affects, for example, temperature, precipitation, wind, and surface heat flux over the North Atlantic, and over large parts of Europe. In observations we find enhanced sub-decadal variability of the NAO index that goes along with a dipolar sea surface temperature (SST) pattern. The corresponding SLP and SST patterns are reproduced in a control experiment of the Kiel Climate Model (KCM). Large-scale air-sea interaction is suggested to be essential for the North Atlantic sub-decadal variability in the KCM. The Atlantic Meridional Overturning Circulation (AMOC) plays a key role, setting the timescale of the variability by providing a delayed negative feedback to the NAO. The interplay of the NAO and the AMOC on the sub-decadal timescale is further investigated in the CMIP5 model ensemble. For example, the average CMIP5 model AMOC pattern associated with sub-decadal variability is characterized by a deep-reaching dipolar structure, similar to the KCM's sub-decadal AMOC variability pattern. The results suggest that dynamical air-sea interactions are crucial to generate enhanced sub-decadal variability in the North Atlantic climate.

High-resolution paleoclimate records of Holocene hydroclimatic variability in the Eastern Colombian Andes from Lago de Tota

NASA Astrophysics Data System (ADS)

Ahmed, M. N.; Bird, B. W.; Escobar, J.; Polissar, P. J.

2017-12-01

The Northern Hemisphere (NH) South American Monsoon (SAM) is a significant source of precipitation for the North Andes (north of 0˚) and has major control over regional hydroclimate variability. Holocene-length histories of NH SAM variability are few compared to the Southern Hemisphere (SH), limiting understanding of how these systems are connected on orbital and shorter timescales. Here, we present multi-proxy lake-sediment-based paleoclimate and paleohydrologic reconstructions from Lago de Tota, Colombia, using sedimentological, geochemical and leaf-wax hydrogen isotopic indicators from radiometically dated cores. The results indicate periods of wet and dry climate phases during the past 9000 BP with an average Holocene sedimentation rate 33cm/kyr. An increase in total organic matter (TOM) content and finer grain-size distributions was observed from 8000 to 3200 BP, suggesting a period of high lake level. This was followed by lower TOM and coarser grain sizes, suggesting lower lake levels from 3200 BP to the present. Although Tota's lake level pattern is antiphased with other lake level reconstructions from the NH and SH Andes, it is consistent with hypothesized changes in atmospheric convection over the Andes during the Holocene and the way in which they would be modified by the so-called dry island effect in the Colombian Andes. This suggests that a common forcing mechanism can be invoked to explain differing millennial-scale Andean hydroclimate changes, namely atmospheric convection. Orbital and Pacific atmosphere-forcing are therefore likely to have played a significant role in driving pan-Andean hydroclimate variability based on their inter-hemispheric influence on Andean convection.

Individual-based model of young-of-the-year striped bass population dynamics. II. Factors affecting recruitment in the Potomac River, Maryland

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

Cowan, J.H.; Rose, K.A.; Rutherford, E.S.

1993-05-01

An individual-based model of the population dynamics of young-of-the-year striped bass Morone saxatilis in the Potomac River, Maryland, was used to test the hypothesis that historically high recruitment variability can be explained by changes in environmental and biological factors that result in relatively small changes in growth and mortality rates of striped bass larvae. The four factors examined were (1) size distribution of female parents, (2) zooplankton prey density during the development of striped bass larvae, (3) density of completing larval white perch M. americana, and (4) temperature during larval development. Simulation results suggest that variations in female size andmore » in prey for larvae alone could cause 10-fold variability in recruitment. But no single factor alone caused changes in vital rates of age-0 fish that could account for the 145-fold variability in the Potomac River index of juvenile recruitment. However, combined positive or negative effects of two or more factors resulted in more than a 150-fold simulated recruitment variability, suggesting that combinations of factors can account for the high observed annual variability in striped bass recruitment success. Higher cumulative mortality of feeding larvae and younger life stages than of juveniles was common to all simulations. supporting the contention that striped bass year-class strength is determined prior to metamorphosis. 76 refs., 7 figs., 4 tabs.« less

Benthic communities in the deep Mediterranean Sea: exploring microbial and meiofaunal patterns in slope and basin ecosystems

NASA Astrophysics Data System (ADS)

Sevastou, K.; Lampadariou, N.; Polymenakou, P. N.; Tselepides, A.

2013-07-01

The long-held perception of the deep sea consisting of monotonous slopes and uniform oceanic basins has over the decades given way to the idea of a complex system with wide habitat heterogeneity. Under the prism of a highly diverse environment, a large dataset was used to describe and compare spatial patterns of the dominant small-size components of deep-sea benthos, metazoan meiofauna and microbes, from Mediterranean basins and slopes. A grid of 73 stations sampled at five geographical areas along the central-eastern Mediterranean Basin (central Mediterranean, northern Aegean Sea, Cretan Sea, Libyan Sea, eastern Levantine) spanning over 4 km in depth revealed a high diversity, irrespective of the benthic group or level of taxonomic analysis. A common decreasing bathymetric trend was detected for meiobenthic abundance, major taxa diversity and nematode genera richness, but no differences were found between the two habitats (basin vs slope). In contrast, microbial richness is significantly higher at the basin ecosystem and tends to increase with depth. Multivariate analyses (β- and δ-diversity and ordination analysis) complemented these results and underlined the high within-habitat variability of benthic communities. Meiofaunal communities in particular were found to change gradually and vary more towards the abyss. On the other hand, microbial communities were highly variable, even among samples of the same area, habitat and bathymetry. A significant proportion of the variation of benthic communities and their descriptors was explained by depth and proxies of food availability (sedimentary pigments and organic content), but the combination of predictor variables and the strength of the relationship varied depending on the data set used (based on type of habitat, benthic component, taxonomic level). This, along with the observed high within-habitat variability suggests that other factors, which tend to vary at local scale (hydrodynamics, substrate structure, geochemistry, food quality, etc.), may also relate to the observed benthic patterns. Overall, the results presented here suggest that differences in small-size benthos between the basin and slope habitats are neither strong nor consistent; it appears that within-habitat variability is high, differences among depth ranges are important and further investigation of possible environmental drivers of benthic patterns is needed.

A search for cataclysmic binaries containing strongly magnetic white dwarfs

NASA Technical Reports Server (NTRS)

Bond, H. E.; Chanmugam, G.

1982-01-01

The AM Herculis type binaries which contain accreting white dwarfs with surface magnetic fields of a few times 10 to the seventh power gauss were studied. If white dwarfs in cataclysmic binaries have a range of field strengths similar to that among single white dwarfs. AM Her like systems should exist with fields as high as 3 x 10 to the eighth power gauss. It is suggested that such objects will not have the strong optical polarization of the AM Her variables; however, they exhibit high harmonic cyclotron emission, making them spectacular UV sources. We made IUE observations of seven candidate cataclysmic variables selected for optical similarity to AM Her binaries. Although all seven objects were detected in the UV, none display unusually strong UV continua. It is suggested that the distribution of magnetic field strengths among single white dwarfs may be different from that among binaries.

Mind over matter: cognitive - behavioral determinants of emotional distress in multiple sclerosis patients.

PubMed

Chalk, Holly McCartney

2007-10-01

Given the high incidence and unique symptomatology of depression in multiple sclerosis (MS) patients, the current study examined the role of cognitive and behavioral variables in predicting psychosocial adjustment in this population, in order to suggest psychotherapeutic interventions tailored specifically to MS patients. Data from 329 MS patients indicated that problem solving coping, acceptance coping, and challenge appraisals were associated with positive psychological adjustment (i.e., high life satisfaction, low depression and anxiety), whereas variables measuring disease severity (i.e., illness duration, subjective health status, and self-reported disability) were not associated with adjustment. These findings suggest that MS patients' psychological outcomes are more related to controllable cognitive and behavioral factors than to the physical effects of the disease. Consequently, it is expected that interventions that target these specific coping strategies and cognitive appraisals will be effective in treating the emotional effects of MS.

Contextualization: Memory Formation and Retrieval in a Nested Environment

NASA Astrophysics Data System (ADS)

Piefke, Martina; Markowitsch, Hans J.

Episodic memory functions are highly context-dependent. This is true for both experimental and autobiographical episodic memory. We here review neuropsychological and neuroimaging evidence for effects of differential encoding and retrieval contexts on episodic memory performance as well as the underlying neurofunctional mechanisms. In studies of laboratory episodic memory, the influence of context parameters can be assessed by experimental manipulations. Such experiments suggest that contextual variables mainly affect prefrontal functions supporting executive processes involved in episodic learning and retrieval. Context parameters affecting episodic autobiographical memory are far more complex and cannot easily be controlled. Data support the view that not only prefrontal, but also further medial temporal and posterior parietal regions mediating the re-experience and emotional evaluation of personal memories are highly influenced by changing contextual variables of memory encoding and retrieval. Based on our review of available data, we thus suggest that experimental and autobiographical episodic memories are influenced by both overlapping and differential context parameters.

Material variability as measured by low temperature electrical resistivity.

NASA Technical Reports Server (NTRS)

Clark, A. F.; Tryon, P. V.

1972-01-01

Low temperature electrical resistivity was used to determine the material variability (1) between different manufacturers, (2) between different heats from the same manufacturer, and (3) within a given heat for Al 2024, Al-5% Mg alloys, Inconel 718, A286 stainless, and AISI 316. Generally, the coefficient of variation for solution annealed alloys ranged from 1.2 to 14% between manufacturers, 0.8 to 5.1% between heats, and 0.1 to 1.6% within a heat with stainless steels at the low ends and Al 2024 at the high ends. The variability is increased if the material is in a precipitation-hardened condition. A statistical analysis suggests that the variability within a heat is non-normal.

Spatial heterogeneity of within-stream methane concentrations

NASA Astrophysics Data System (ADS)

Crawford, John T.; Loken, Luke C.; West, William E.; Crary, Benjamin; Spawn, Seth A.; Gubbins, Nicholas; Jones, Stuart E.; Striegl, Robert G.; Stanley, Emily H.

2017-05-01

Streams, rivers, and other freshwater features may be significant sources of CH4 to the atmosphere. However, high spatial and temporal variabilities hinder our ability to understand the underlying processes of CH4 production and delivery to streams and also challenge the use of scaling approaches across large areas. We studied a stream having high geomorphic variability to assess the underlying scale of CH4 spatial variability and to examine whether the physical structure of a stream can explain the variation in surface CH4. A combination of high-resolution CH4 mapping, a survey of groundwater CH4 concentrations, quantitative analysis of methanogen DNA, and sediment CH4 production potentials illustrates the spatial and geomorphic controls on CH4 emissions to the atmosphere. We observed significant spatial clustering with high CH4 concentrations in organic-rich stream reaches and lake transitions. These sites were also enriched in the methane-producing mcrA gene and had highest CH4 production rates in the laboratory. In contrast, mineral-rich reaches had significantly lower concentrations and had lesser abundances of mcrA. Strong relationships between CH4 and the physical structure of this aquatic system, along with high spatial variability, suggest that future investigations will benefit from viewing streams as landscapes, as opposed to ecosystems simply embedded in larger terrestrial mosaics. In light of such high spatial variability, we recommend that future workers evaluate stream networks first by using similar spatial tools in order to build effective sampling programs.

The cost of empathy: Parent-adolescent conflict predicts emotion dysregulation for highly empathic youth.

PubMed

Van Lissa, Caspar J; Hawk, Skyler T; Koot, Hans M; Branje, Susan; Meeus, Wim H J

2017-09-01

Empathy plays a key role in maintaining close relationships and promoting prosocial conflict resolution. However, research has not addressed the potential emotional cost of adolescents' high empathy, particularly when relationships are characterized by more frequent conflict. The present 6-year longitudinal study (N = 467) investigated whether conflict with parents predicted emotion dysregulation more strongly for high-empathy adolescents than for lower-empathy adolescents. Emotion dysregulation was operationalized at both the experiential level, using mood diary data collected for 3 weeks each year, and at the dispositional level, using annual self-report measures. In line with predictions, we found that more frequent adolescent-parent conflict predicted greater day-to-day mood variability and dispositional difficulties in emotion regulation for high-empathy adolescents, but not for average- and low-empathy adolescents. Mood variability and difficulties in emotion regulation, in turn, also predicted increased conflict with parents. These links were not moderated by empathy. Moreover, our research allowed for a novel investigation of the interplay between experiential and dispositional emotion dysregulation. Day-to-day mood variability predicted increasing dispositional difficulties in emotion regulation over time, which suggests that experiential dysregulation becomes consolidated into dispositional difficulties in emotion regulation. Moderated mediation analyses revealed that, for high-empathy adolescents, conflict was a driver of this dysregulation consolidation process. Finally, emotion dysregulation played a role in overtime conflict maintenance for high-empathy adolescents. This suggests that, through emotion dysregulation, high empathy may paradoxically also contribute to maintaining negative adolescent-parent interactions. Our research indicates that high empathy comes at a cost when adolescent-parent relationships are characterized by greater negativity. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Anxiety, attention, and decision making: The moderating role of heart rate variability.

PubMed

Ramírez, Encarnación; Ortega, Ana Raquel; Reyes Del Paso, Gustavo A

2015-12-01

The current exploratory research examined whether high frequency heart rate variability (HF-HRV) modulates the association between anxiety and (1) executive attentional control during situations involving neutral stimuli, in which the distractor stimuli are in conflict with the target stimulus, and (2) risk aversion in decision making. Forty-five participants (21 with low and 24 with high trait-anxiety) performed a modified version of the Attention Network Test to measure attentional control, and the Balloon Analog Risk Task to measure risk aversion. HF-HRV was recorded during a rest period before completion of the tasks. Results showed that individuals with high anxiety and low HF-HRV have worse attentional control in the face of conflicting information as well as greater risk aversion, in comparison with individuals with both high anxiety and high HF-HRV or low anxiety (regardless of HF-HRV). HF-HRV was positively associated with attentional control and negatively associated with risk aversion. Furthermore, a strong negative association was observed between attentional control and risk aversion. These results suggest that HF-HRV modulates the influence of anxiety on both attentional control to neutral stimuli, and risk aversion in decision making. Greater HF-HRV appears to fulfill a protective role in highly anxious individuals. The associations observed also suggest that executive control of attention plays a relevant role in decision making. These results support the relevance of the autonomic nervous system in sustained cognition and are in accordance with theories in which vagal-mediated heart rate variability is taken as an indicator of prefrontal cortex inhibitory influences. Copyright © 2015 Elsevier B.V. All rights reserved.

Natural trophic variability in a large, oligotrophic, near-pristine lake

USGS Publications Warehouse

Young, Talia; Jensen, Olaf P.; Weidel, Brian C.; Chandra, Sudeep

2015-01-01

Conclusions drawn from stable isotope data can be limited by an incomplete understanding of natural isotopic variability over time and space. We quantified spatial and temporal variability in fish carbon and nitrogen stable isotopes in Lake Hövsgöl, Mongolia, a large, remote, oligotrophic lake with an unusually species-poor fish community. The fish community demonstrated a high degree of trophic level overlap. Variability in δ13C was inversely related to littoral-benthic dependence, with pelagic species demonstrating more δ13C variability than littoral-benthic species. A mixed effects model suggested that space (sampling location) had a greater impact than time (collection year) on both δ13C and δ15N variability. The observed variability in Lake Hövsgöl was generally greater than isotopic variability documented in other large, oligotrophic lakes, similar to isotopic shifts attributed to introduced species, and less than isotopic shifts attributed to anthropogenic chemical changes such as eutrophication. This work complements studies on isotopic variability and changes in other lakes around the world.

Decadal variability of the Tropical Atlantic Ocean Surface Temperature in shipboard measurements and in a Global Ocean-Atmosphere model

NASA Technical Reports Server (NTRS)

Mehta, Vikram M.; Delworth, Thomas

1995-01-01

Sea surface temperature (SST) variability was investigated in a 200-yr integration of a global model of the coupled oceanic and atmospheric general circulations developed at the Geophysical Fluid Dynamics Laboratory (GFDL). The second 100 yr of SST in the coupled model's tropical Atlantic region were analyzed with a variety of techniques. Analyses of SST time series, averaged over approximately the same subregions as the Global Ocean Surface Temperature Atlas (GOSTA) time series, showed that the GFDL SST anomalies also undergo pronounced quasi-oscillatory decadal and multidecadal variability but at somewhat shorter timescales than the GOSTA SST anomalies. Further analyses of the horizontal structures of the decadal timescale variability in the GFDL coupled model showed the existence of two types of variability in general agreement with results of the GOSTA SST time series analyses. One type, characterized by timescales between 8 and 11 yr, has high spatial coherence within each hemisphere but not between the two hemispheres of the tropical Atlantic. A second type, characterized by timescales between 12 and 20 yr, has high spatial coherence between the two hemispheres. The second type of variability is considerably weaker than the first. As in the GOSTA time series, the multidecadal variability in the GFDL SST time series has approximately opposite phases between the tropical North and South Atlantic Oceans. Empirical orthogonal function analyses of the tropical Atlantic SST anomalies revealed a north-south bipolar pattern as the dominant pattern of decadal variability. It is suggested that the bipolar pattern can be interpreted as decadal variability of the interhemispheric gradient of SST anomalies. The decadal and multidecadal timescale variability of the tropical Atlantic SST, both in the actual and in the GFDL model, stands out significantly above the background 'red noise' and is coherent within each of the time series, suggesting that specific sets of processes may be responsible for the choice of the decadal and multidecadal timescales. Finally, it must be emphasized that the GFDL coupled ocean-atmosphere model generates the decadal and multidecadal timescale variability without any externally applied force, solar or lunar, at those timescales.

Scales of Spatial Heterogeneity of Plastic Marine Debris in the Northeast Pacific Ocean

PubMed Central

Goldstein, Miriam C.; Titmus, Andrew J.; Ford, Michael

2013-01-01

Plastic debris has been documented in many marine ecosystems, including remote coastlines, the water column, the deep sea, and subtropical gyres. The North Pacific Subtropical Gyre (NPSG), colloquially called the “Great Pacific Garbage Patch,” has been an area of particular scientific and public concern. However, quantitative assessments of the extent and variability of plastic in the NPSG have been limited. Here, we quantify the distribution, abundance, and size of plastic in a subset of the eastern Pacific (approximately 20–40°N, 120–155°W) over multiple spatial scales. Samples were collected in Summer 2009 using surface and subsurface plankton net tows and quantitative visual observations, and Fall 2010 using surface net tows only. We documented widespread, though spatially variable, plastic pollution in this portion of the NPSG and adjacent waters. The overall median microplastic numerical concentration in Summer 2009 was 0.448 particles m−2 and in Fall 2010 was 0.021 particles m−2, but plastic concentrations were highly variable over the submesoscale (10 s of km). Size-frequency spectra were skewed towards small particles, with the most abundant particles having a cross-sectional area of approximately 0.01 cm2. Most microplastic was found on the sea surface, with the highest densities detected in low-wind conditions. The numerical majority of objects were small particles collected with nets, but the majority of debris surface area was found in large objects assessed visually. Our ability to detect high-plastic areas varied with methodology, as stations with substantial microplastic did not necessarily also contain large visually observable objects. A power analysis of our data suggests that high variability of surface microplastic will make future changes in abundance difficult to detect without substantial sampling effort. Our findings suggest that assessment and monitoring of oceanic plastic debris must account for high spatial variability, particularly in regards to the evaluation of initiatives designed to reduce marine debris. PMID:24278233

Scales of spatial heterogeneity of plastic marine debris in the northeast pacific ocean.

PubMed

Goldstein, Miriam C; Titmus, Andrew J; Ford, Michael

2013-01-01

Plastic debris has been documented in many marine ecosystems, including remote coastlines, the water column, the deep sea, and subtropical gyres. The North Pacific Subtropical Gyre (NPSG), colloquially called the "Great Pacific Garbage Patch," has been an area of particular scientific and public concern. However, quantitative assessments of the extent and variability of plastic in the NPSG have been limited. Here, we quantify the distribution, abundance, and size of plastic in a subset of the eastern Pacific (approximately 20-40°N, 120-155°W) over multiple spatial scales. Samples were collected in Summer 2009 using surface and subsurface plankton net tows and quantitative visual observations, and Fall 2010 using surface net tows only. We documented widespread, though spatially variable, plastic pollution in this portion of the NPSG and adjacent waters. The overall median microplastic numerical concentration in Summer 2009 was 0.448 particles m(-2) and in Fall 2010 was 0.021 particles m(-2), but plastic concentrations were highly variable over the submesoscale (10 s of km). Size-frequency spectra were skewed towards small particles, with the most abundant particles having a cross-sectional area of approximately 0.01 cm(2). Most microplastic was found on the sea surface, with the highest densities detected in low-wind conditions. The numerical majority of objects were small particles collected with nets, but the majority of debris surface area was found in large objects assessed visually. Our ability to detect high-plastic areas varied with methodology, as stations with substantial microplastic did not necessarily also contain large visually observable objects. A power analysis of our data suggests that high variability of surface microplastic will make future changes in abundance difficult to detect without substantial sampling effort. Our findings suggest that assessment and monitoring of oceanic plastic debris must account for high spatial variability, particularly in regards to the evaluation of initiatives designed to reduce marine debris.

Characterizing Temperature Variability and Associated Large Scale Meteorological Patterns Across South America

NASA Astrophysics Data System (ADS)

Detzer, J.; Loikith, P. C.; Mechoso, C. R.; Barkhordarian, A.; Lee, H.

2017-12-01

South America's climate varies considerably owing to its large geographic range and diverse topographical features. Spanning the tropics to the mid-latitudes and from high peaks to tropical rainforest, the continent experiences an array of climate and weather patterns. Due to this considerable spatial extent, assessing temperature variability at the continent scale is particularly challenging. It is well documented in the literature that temperatures have been increasing across portions of South America in recent decades, and while there have been many studies that have focused on precipitation variability and change, temperature has received less scientific attention. Therefore, a more thorough understanding of the drivers of temperature variability is critical for interpreting future change. First, k-means cluster analysis is used to identify four primary modes of temperature variability across the continent, stratified by season. Next, composites of large scale meteorological patterns (LSMPs) are calculated for months assigned to each cluster. Initial results suggest that LSMPs, defined using meteorological variables such as sea level pressure (SLP), geopotential height, and wind, are able to identify synoptic scale mechanisms important for driving temperature variability at the monthly scale. Some LSMPs indicate a relationship with known recurrent modes of climate variability. For example, composites of geopotential height suggest that the Southern Annular Mode is an important, but not necessarily dominant, component of temperature variability over southern South America. This work will be extended to assess the drivers of temperature extremes across South America.

Controls on the spatial variability of key soil properties: comparing field data with a mechanistic soilscape evolution model

NASA Astrophysics Data System (ADS)

Vanwalleghem, T.; Román, A.; Giraldez, J. V.

2016-12-01

There is a need for better understanding the processes influencing soil formation and the resulting distribution of soil properties. Soil properties can exhibit strong spatial variation, even at the small catchment scale. Especially soil carbon pools in semi-arid, mountainous areas are highly uncertain because bulk density and stoniness are very heterogeneous and rarely measured explicitly. In this study, we explore the spatial variability in key soil properties (soil carbon stocks, stoniness, bulk density and soil depth) as a function of processes shaping the critical zone (weathering, erosion, soil water fluxes and vegetation patterns). We also compare the potential of a geostatistical versus a mechanistic soil formation model (MILESD) for predicting these key soil properties. Soil core samples were collected from 67 locations at 6 depths. Total soil organic carbon stocks were 4.38 kg m-2. Solar radiation proved to be the key variable controlling soil carbon distribution. Stone content was mostly controlled by slope, indicating the importance of erosion. Spatial distribution of bulk density was found to be highly random. Finally, total carbon stocks were predicted using a random forest model whose main covariates were solar radiation and NDVI. The model predicts carbon stocks that are double as high on north versus south-facing slopes. However, validation showed that these covariates only explained 25% of the variation in the dataset. Apparently, present-day landscape and vegetation properties are not sufficient to fully explain variability in the soil carbon stocks in this complex terrain under natural vegetation. This is attributed to a high spatial variability in bulk density and stoniness, key variables controlling carbon stocks. Similar results were obtained with the mechanistic soil formation model MILESD, suggesting that more complex models might be needed to further explore this high spatial variability.

High Variability in Cellular Stoichiometry of Carbon, Nitrogen, and Phosphorus Within Classes of Marine Eukaryotic Phytoplankton Under Sufficient Nutrient Conditions.

PubMed

Garcia, Nathan S; Sexton, Julie; Riggins, Tracey; Brown, Jeff; Lomas, Michael W; Martiny, Adam C

2018-01-01

Current hypotheses suggest that cellular elemental stoichiometry of marine eukaryotic phytoplankton such as the ratios of cellular carbon:nitrogen:phosphorus (C:N:P) vary between phylogenetic groups. To investigate how phylogenetic structure, cell volume, growth rate, and temperature interact to affect the cellular elemental stoichiometry of marine eukaryotic phytoplankton, we examined the C:N:P composition in 30 isolates across 7 classes of marine phytoplankton that were grown with a sufficient supply of nutrients and nitrate as the nitrogen source. The isolates covered a wide range in cell volume (5 orders of magnitude), growth rate (<0.01-0.9 d -1 ), and habitat temperature (2-24°C). Our analysis indicates that C:N:P is highly variable, with statistical model residuals accounting for over half of the total variance and no relationship between phylogeny and elemental stoichiometry. Furthermore, our data indicated that variability in C:P, N:P, and C:N within Bacillariophyceae (diatoms) was as high as that among all of the isolates that we examined. In addition, a linear statistical model identified a positive relationship between diatom cell volume and C:P and N:P. Among all of the isolates that we examined, the statistical model identified temperature as a significant factor, consistent with the temperature-dependent translation efficiency model, but temperature only explained 5% of the total statistical model variance. While some of our results support data from previous field studies, the high variability of elemental ratios within Bacillariophyceae contradicts previous work that suggests that this cosmopolitan group of microalgae has consistently low C:P and N:P ratios in comparison with other groups.

Resilience, rapid transitions and regime shifts: fingerprinting the responses of Lake Żabińskie (NE Poland) to climate variability and human disturbance since 1000 AD

NASA Astrophysics Data System (ADS)

Tylmann, Wojciech; Hernández-Almeida, Iván; Grosjean, Martin; José Gómez Navarro, Juan; Larocque-Tobler, Isabelle; Bonk, Alicja; Enters, Dirk; Ustrzycka, Alicja; Piotrowska, Natalia; Przybylak, Rajmund; Wacnik, Agnieszka; Witak, Małgorzata

2016-04-01

Rapid ecosystem transitions and adverse effects on ecosystem services as responses to combined climate and human impacts are of major concern. Yet few quantitative observational data exist, particularly for ecosystems that have a long history of human intervention. Here, we combine quantitative summer and winter climate reconstructions, climate model simulations and proxies for three major environmental pressures (land use, nutrients and erosion) to explore the system dynamics, resilience, and the role of disturbance regimes in varved eutrophic Lake Żabińskie since AD 1000. Comparison between regional and global climate simulations and quantitative climate reconstructions indicate that proxy data capture noticeably natural forced climate variability, while internal variability appears as the dominant source of climate variability in the climate model simulations during most parts of the last millennium. Using different multivariate analyses and change point detection techniques, we identify ecosystem changes through time and shifts between rather stable states and highly variable ones, as expressed by the proxies for land-use, erosion and productivity in the lake. Prior to AD 1600, the lake ecosystem was characterized by a high stability and resilience against considerable observed natural climate variability. In contrast, lake-ecosystem conditions started to fluctuate at high frequency across a broad range of states after AD 1600. The period AD 1748-1868 represents the phase with the strongest human disturbance of the ecosystem. Analyses of the frequency of change points in the multi-proxy dataset suggests that the last 400 years were highly variable and flickering with increasing vulnerability of the ecosystem to the combined effects of climate variability and anthropogenic disturbances. This led to significant rapid ecosystem transformations.

HIGHLY VARIABLE YOUNG MASSIVE STARS IN ATLASGAL CLUMPS

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

Kumar, M. S. N.; Contreras Peña, C.; Lucas, P. W.

High-amplitude variability in young stellar objects (YSOs) is usually associated with episodic accretion events. It has not been observed so far in massive YSOs. Here, the high-amplitude variable star sample of Contreras Peña et al. has been used to search for highly variable (Δ K  ≥ 1 mag) sources coinciding with dense clumps mapped using the 850  μ m continuum emission by the ATLASGAL survey. A total of 18 variable sources are centered on the submillimeter clump peaks and coincide (<1″) with a 24  μ m point or compact (<10″) source. Of these 18 sources, 13 can be fit by YSOmore » models. The 13 variable YSOs (VYSOs) have luminosities of ∼10{sup 3} L {sub ⊙}, an average mass of 8  M {sub ⊙}, and a range of ages up to 10{sup 6} yr. A total of 11 of these 13 VYSOs are located in the midst of infrared dark clouds. Nine of the 13 sources have Δ K  > 2 mag, significantly higher compared to the mean variability of the entire VVV sample. The light curves of these objects sampled between 2010 and 2015 display rising, declining, or quasi-periodic behavior but no clear periodicity. Light-curve analysis using the Plavchan method shows that the most prominent phased signals have periods of a few hundred days. The nature and timescale of variations found in 6.7 Ghz methanol maser emission in massive stars are similar to that of the VYSO light curves. We argue that the origin of the observed variability is episodic accretion. We suggest that the timescale of a few hundred days may represent the frequency at which a spiraling disk feeds dense gas to the young massive star.« less

Ross Sea Till Properties: Implications for Ice Sheet Bed Interaction

NASA Astrophysics Data System (ADS)

Halberstadt, A. R.; Anderson, J. B.; Simkins, L.; Prothro, L. O.; Bart, P. J.

2015-12-01

Since the discovery of a pervasive shearing till layer underlying Ice Stream B, the scientific community has categorized subglacial diamictons as either deformation till or lodgement till primarily based on shear strength. Deformation till is associated with streaming ice, formed through subglacial deformation of unconsolidated sediments. Lodgement till is believed to be deposited by the plastering of sediment entrained at the base of slow-flowing ice onto a rigid bed. Unfortunately, there has been a paucity of quantitative data on the spatial distribution of shear strength across the continental shelf. Cores collected from the Ross Sea on cruises NBP1502 and NBP9902 provide a rich dataset that can be used to interpret till shear strength variability. Till strengths are analyzed within the context of: (1) geologic substrate; (2) water content and other geotechnical properties; (3) ice sheet retreat history; and (4) geomorphic framework. Tills display a continuum of shear strengths rather than a bimodal distribution, suggesting that shear strength cannot be used to distinguish between lodgement and deformation till. Where the substrate below the LGM unconformity is comprised of older lithified deposits, till shear strengths are both highly variable within the till unit, as well as highly variable between cores. Conversely, where ice streams flowed across unconsolidated Plio-Pleistocene deposits, shear strengths are low and less variable within the unit and between cores. This suggests greater homogenization of cannibalized tills, and possibly a deeper pervasive shear layer. Coarser-grained tills are observed on banks and bank slopes, with finer tills in troughs. Highly variable and more poorly sorted tills are found in close proximity to sediment-based subglacial meltwater channels, attesting to a change in ice-bed interaction as subglacial water increases. Pellets (rounded sedimentary clasts of till matrix) are observed in Ross Sea cores, suggesting a history of deformation responsible for pellet formation. Till strength was measured in a variety of environments, including mega-scale lineations and grounding zone wedges; ongoing work focuses on evaluating till shear strengths within a geomorphic context. These analyses are used to re-evaluate till genesis, transport, and characterization.

The evolution of the disc variability along the hard state of the black hole transient GX 339-4

NASA Astrophysics Data System (ADS)

De Marco, B.; Ponti, G.; Muñoz-Darias, T.; Nandra, K.

2015-12-01

We report on the analysis of hard-state power spectral density function (PSD) of GX 339-4 down to the soft X-ray band, where the disc significantly contributes to the total emission. At any luminosity probed, the disc in the hard state is intrinsically more variable than in the soft state. However, the fast decrease of disc variability as a function of luminosity, combined with the increase of disc intensity, causes a net drop of fractional variability at high luminosities and low energies, which reminds the well-known behaviour of disc-dominated energy bands in the soft state. The peak frequency of the high-frequency Lorentzian (likely corresponding to the high-frequency break seen in active galactic nuclei, AGN) scales with luminosity, but we do not find evidence for a linear scaling. In addition, we observe that this characteristic frequency is energy dependent. We find that the normalization of the PSD at the peak of the high-frequency Lorentzian decreases with luminosity at all energies, though in the soft band this trend is steeper. Together with the frequency shift, this yields quasi-constant high-frequency (5-20 Hz) fractional rms at high energies, with less than 10 per cent scatter. This reinforces previous claims suggesting that the high-frequency PSD solely scales with black hole mass. On the other hand, this constancy breaks down in the soft band (where the scatter increases to ˜30 per cent). This is a consequence of the additional contribution from the disc component, and resembles the behaviour of optical variability in AGN.

Evidence for divergence of response in Indica, Japonica, and wild rice to high CO2 x temperature interaction

USDA-ARS?s Scientific Manuscript database

Previous studies suggest that the intraspecific variability of rice yield response to rising carbon dioxide concentration, [CO2], could serve as a basis of selection to improve genotypes for future high CO2 conditions. However, assessment of responses to elevated [CO2] must consider air temperature,...

Beyond Correlations: Usefulness of High School GPA and Test Scores in Making College Admissions Decisions

ERIC Educational Resources Information Center

Sawyer, Richard

2013-01-01

Correlational evidence suggests that high school GPA is better than admission test scores in predicting first-year college GPA, although test scores have incremental predictive validity. The usefulness of a selection variable in making admission decisions depends in part on its predictive validity, but also on institutions' selectivity and…

High or low? Comparing high and low-variability phonetic training in adult and child second language learners

PubMed Central

Brown, Helen; Clayards, Meghan

2017-01-01

Background High talker variability (i.e., multiple voices in the input) has been found effective in training nonnative phonetic contrasts in adults. A small number of studies suggest that children also benefit from high-variability phonetic training with some evidence that they show greater learning (more plasticity) than adults given matched input, although results are mixed. However, no study has directly compared the effectiveness of high versus low talker variability in children. Methods Native Greek-speaking eight-year-olds (N = 52), and adults (N = 41) were exposed to the English /i/-/ɪ/ contrast in 10 training sessions through a computerized word-learning game. Pre- and post-training tests examined discrimination of the contrast as well as lexical learning. Participants were randomly assigned to high (four talkers) or low (one talker) variability training conditions. Results Both age groups improved during training, and both improved more while trained with a single talker. Results of a three-interval oddity discrimination test did not show the predicted benefit of high-variability training in either age group. Instead, children showed an effect in the reverse direction—i.e., reliably greater improvements in discrimination following single talker training, even for untrained generalization items, although the result is qualified by (accidental) differences between participant groups at pre-test. Adults showed a numeric advantage for high-variability but were inconsistent with respect to voice and word novelty. In addition, no effect of variability was found for lexical learning. There was no evidence of greater plasticity for phonetic learning in child learners. Discussion This paper adds to the handful of studies demonstrating that, like adults, child learners can improve their discrimination of a phonetic contrast via computerized training. There was no evidence of a benefit of training with multiple talkers, either for discrimination or word learning. The results also do not support the findings of greater plasticity in child learners found in a previous paper (Giannakopoulou, Uther & Ylinen, 2013a). We discuss these results in terms of various differences between training and test tasks used in the current work compared with previous literature. PMID:28584698

High or low? Comparing high and low-variability phonetic training in adult and child second language learners.

PubMed

Giannakopoulou, Anastasia; Brown, Helen; Clayards, Meghan; Wonnacott, Elizabeth

2017-01-01

High talker variability (i.e., multiple voices in the input) has been found effective in training nonnative phonetic contrasts in adults. A small number of studies suggest that children also benefit from high-variability phonetic training with some evidence that they show greater learning (more plasticity) than adults given matched input, although results are mixed. However, no study has directly compared the effectiveness of high versus low talker variability in children. Native Greek-speaking eight-year-olds ( N = 52), and adults ( N = 41) were exposed to the English /i/-/ɪ/ contrast in 10 training sessions through a computerized word-learning game. Pre- and post-training tests examined discrimination of the contrast as well as lexical learning. Participants were randomly assigned to high (four talkers) or low (one talker) variability training conditions. Both age groups improved during training, and both improved more while trained with a single talker. Results of a three-interval oddity discrimination test did not show the predicted benefit of high-variability training in either age group. Instead, children showed an effect in the reverse direction-i.e., reliably greater improvements in discrimination following single talker training, even for untrained generalization items, although the result is qualified by (accidental) differences between participant groups at pre-test. Adults showed a numeric advantage for high-variability but were inconsistent with respect to voice and word novelty. In addition, no effect of variability was found for lexical learning. There was no evidence of greater plasticity for phonetic learning in child learners. This paper adds to the handful of studies demonstrating that, like adults, child learners can improve their discrimination of a phonetic contrast via computerized training. There was no evidence of a benefit of training with multiple talkers, either for discrimination or word learning. The results also do not support the findings of greater plasticity in child learners found in a previous paper (Giannakopoulou, Uther & Ylinen, 2013a). We discuss these results in terms of various differences between training and test tasks used in the current work compared with previous literature.

Hair Cortisol in Twins: Heritability and Genetic Overlap with Psychological Variables and Stress-System Genes.

PubMed

Rietschel, Liz; Streit, Fabian; Zhu, Gu; McAloney, Kerrie; Frank, Josef; Couvy-Duchesne, Baptiste; Witt, Stephanie H; Binz, Tina M; McGrath, John; Hickie, Ian B; Hansell, Narelle K; Wright, Margaret J; Gillespie, Nathan A; Forstner, Andreas J; Schulze, Thomas G; Wüst, Stefan; Nöthen, Markus M; Baumgartner, Markus R; Walker, Brian R; Crawford, Andrew A; Colodro-Conde, Lucía; Medland, Sarah E; Martin, Nicholas G; Rietschel, Marcella

2017-11-10

Hair cortisol concentration (HCC) is a promising measure of long-term hypothalamus-pituitary-adrenal (HPA) axis activity. Previous research has suggested an association between HCC and psychological variables, and initial studies of inter-individual variance in HCC have implicated genetic factors. However, whether HCC and psychological variables share genetic risk factors remains unclear. The aims of the present twin study were to: (i) assess the heritability of HCC; (ii) estimate the phenotypic and genetic correlation between HPA axis activity and the psychological variables perceived stress, depressive symptoms, and neuroticism; using formal genetic twin models and molecular genetic methods, i.e. polygenic risk scores (PRS). HCC was measured in 671 adolescents and young adults. These included 115 monozygotic and 183 dizygotic twin-pairs. For 432 subjects PRS scores for plasma cortisol, major depression, and neuroticism were calculated using data from large genome wide association studies. The twin model revealed a heritability for HCC of 72%. No significant phenotypic or genetic correlation was found between HCC and the three psychological variables of interest. PRS did not explain variance in HCC. The present data suggest that HCC is highly heritable. However, the data do not support a strong biological link between HCC and any of the investigated psychological variables.

[Autoaggression and pulse rate--a longitudinal study].

PubMed

Rohmann, U H; Elbing, U; Hartmann, H

1988-12-01

This article presents a model of autoaggressive behavior in which a distinction is made between determining and maintaining factors. Specific environmental, in particular social, and organismic variables are linked to them. The two types of variables interact, thus causing or maintaining autoaggressive behavior. A theory of autoaggression must therefore rely on multicausal/multimodal explanations. A connection between autoaggression and a high level of arousal suggests itself. In this single-case longitudinal study a comparison was made between heart rate and frequency of autoaggressive behavior. High heart rates were found to be correlated with low frequencies of autoaggressive behavior and vice versa. Decreasing autoaggressive behavior was coupled with increasing muscle relaxation and increasing motor activity. However, abnormally high heart rates were associated with both low and high levels of motor activity.

The macro-structural variability of the human neocortex.

PubMed

Kruggel, Frithjof

2018-05-15

The human neocortex shows a considerable individual structural variability. While primary gyri and sulci are found in all normally developed brains and bear clear-cut gross structural descriptions, secondary structures are highly variable and not present in all brains. The blend of common and individual structures poses challenges when comparing structural and functional results from quantitative neuroimaging studies across individuals, and sets limits on the precision of location information much above the spatial resolution of current neuroimaging methods. This work aimed at quantifying structural variability on the neocortex, and at assessing the spatial relationship between regions common to all brains and their individual structural variants. Based on structural MRI data provided as the "900 Subjects Release" of the Human Connectome Project, a data-driven analytic approach was employed here from which the definition of seven cortical "communities" emerged. Apparently, these communities comprise common regions of structural features, while the individual variability is confined within a community. Similarities between the community structure and the state of the brain development at gestation week 32 lead suggest that communities are segregated early. Subdividing the neocortex into communities is suggested as anatomically more meaningful than the traditional lobar structure. Copyright © 2018 Elsevier Inc. All rights reserved.

Microgravity alters respiratory sinus arrhythmia and short-term heart rate variability in humans

NASA Technical Reports Server (NTRS)

Migeotte, P-F; Prisk, G. Kim; Paiva, M.; West, J. B. (Principal Investigator)

2003-01-01

We studied heart rate (HR), heart rate variability (HRV), and respiratory sinus arrhythmia (RSA) in four male subjects before, during, and after 16 days of spaceflight. The electrocardiogram and respiration were recorded during two periods of 4 min controlled breathing at 7.5 and 15 breaths/min in standing and supine postures on the ground and in microgravity. Low (LF)- and high (HF)-frequency components of the short-term HRV (< or =3 min) were computed through Fourier spectral analysis of the R-R intervals. Early in microgravity, HR was decreased compared with both standing and supine positions and had returned to the supine value by the end of the flight. In microgravity, overall variability, the LF-to-HF ratio, and RSA amplitude and phase were similar to preflight supine values. Immediately postflight, HR increased by approximately 15% and remained elevated 15 days after landing. LF/HF was increased, suggesting an increased sympathetic control of HR standing. The overall variability and RSA amplitude in supine decreased postflight, suggesting that vagal tone decreased, which coupled with the decrease in RSA phase shift suggests that this was the result of an adaptation of autonomic control of HR to microgravity. In addition, these alterations persisted for at least 15 days after return to normal gravity (1G).

Climate-driven unsteady denudation and sediment flux in a high-relief unglaciated catchment-fan using 26Al and 10Be: Panamint Valley, California

NASA Astrophysics Data System (ADS)

Mason, Cody C.; Romans, Brian W.

2018-06-01

Environmental changes within erosional catchments of sediment routing systems are predicted to modulate sediment transfer dynamics. However, empirical and numerical models that predict such phenomena are difficult to test in natural systems over multi-millennial timescales. Tectonic boundary conditions and climate history in the Panamint Range, California, are relatively well-constrained by existing low-temperature thermochronology and regional multi-proxy paleoclimate studies, respectively. Catchment-fan systems present there minimize sediment storage and recycling, offering an excellent natural laboratory to test models of climate-sedimentary dynamics. We used stratigraphic characterization and cosmogenic radionuclides (CRNs; 26Al and 10Be) in the Pleasant Canyon complex (PCC), a linked catchment-fan system, to examine the effects of Pleistocene high-magnitude, high-frequency climate change on CRN-derived denudation rates and sediment flux in a high-relief, unglaciated catchment-fan system. Calculated 26Al/10Be burial ages from 13 samples collected in an ∼180 m thick outcropping stratigraphic succession range from ca. 1.55 ± 0.22 Ma in basal strata, to ca. 0.36 ± 0.18-0.52 ± 0.20 Ma within the uppermost part of the succession. The mean long-term CRN-derived paleodenudation rate, 36 ± 8 mm/kyr (1σ), is higher than the modern rate of 24 ± 0.6 mm/kyr from Pleasant Canyon, and paleodenudation rates during the middle Pleistocene display some high-frequency variability in the high end (up to 54 ± 10 mm/kyr). The highest CRN-derived denudation rates are associated with stratigraphic evidence for increased precipitation during glacial-pluvial events after the middle Pleistocene transition (post ca. 0.75 Ma), suggesting 100 kyr Milankovitch periodicity could drive the observed variability. We investigated the potential for non-equilibrium sedimentary processes, i.e. increased landslides or sediment storage/recycling, to influence apparent paleodenudation rates; end-member mixing models suggest that a mixture of >50% low-CRN-concentration sediment from landslides is required to produce the largest observed increase in paleodenudation rate. The overall pattern of CRN-derived burial ages, paleodenudation rates, and stratigraphic facies suggests Milankovitch timescale climate transitions drive variability in catchment denudation rates and sediment flux, or alternatively that climate transitions affect sedimentary process regimes that result in measurable variability of CRN concentrations in unglaciated catchment-fan systems.

Changes of heart rate variability and prefrontal oxygenation during Tai Chi practice versus arm ergometer cycling.

PubMed

Lu, Xi; Hui-Chan, Christina Wan-Ying; Tsang, William Wai-Nam

2016-11-01

[Purpose] Exercise has been shown to improve cardiovascular fitness and cognitive function. Whether the inclusion of mind over exercise would increase parasympathetic control of the heart and brain activities more than general exercise at a similar intensity is not known. The aim of this study was to compare the effects of Tai Chi (mind-body exercise) versus arm ergometer cycling (body-focused exercise) on the heart rate variability and prefrontal oxygenation level. [Subjects and Methods] A Tai Chi master was invited to perform Tai Chi and arm ergometer cycling with similar exercise intensity on two separate days. Heart rate variability and prefrontal oxyhemoglobin levels were measured continuously by a RR recorder and near-infrared spectroscopy, respectively. [Results] During Tai Chi exercise, spectral analysis of heart rate variability demonstrated a higher high-frequency power as well as a lower low-frequency/high-frequency ratio than during ergometer cycling, suggesting increased parasympathetic and decreased sympathetic control of the heart. Also, prefrontal oxyhemoglobin and total hemoglobin levels were higher than those during arm ergometer exercise. [Conclusion] These findings suggest that increased parasympathetic control of the heart and prefrontal activities may be associated with Tai Chi practice. Having a "mind" component in Tai Chi could be more beneficial for older adults' cardiac health and cognitive function than body-focused ergometer cycling.

Japanese and Taiwanese pelagic longline fleet dynamics and the impacts of climate change in the southern Indian Ocean

NASA Astrophysics Data System (ADS)

Michael, P. E.; Wilcox, C.; Tuck, G. N.; Hobday, A. J.; Strutton, P. G.

2017-06-01

Climate change is projected to continue shifting the distribution of marine species, leading to changes in local assemblages and different interactions with human activities. With regard to fisheries, understanding the relationship between fishing fleets, target species catch per unit effort (CPUE), and the environment enhances our ability to anticipate fisher response and is an essential step towards proactive management. Here, we explore the potential impact of climate change in the southern Indian Ocean by modelling Japanese and Taiwanese pelagic longline fleet dynamics. We quantify the mean and variability of target species CPUE and the relative value and cost of fishing in different areas. Using linear mixed models, we identify fleet-specific effort allocation strategies most related to observed effort and predict the future distribution of effort and tuna catch under climate change for 2063-2068. The Japanese fleet's strategy targets high-value species and minimizes the variability in CPUE of the primary target species. Conversely, the Taiwanese strategy indicated flexible targeting of a broad range of species, fishing in areas of high and low variability in catch, and minimizing costs. The projected future mean and variability in CPUE across species suggest a slight increase in CPUE in currently high CPUE areas for most species. The corresponding effort projections suggest a slight increase in Japanese effort in the western and eastern study area, and Taiwanese effort increasing east of Madagascar. This approach provides a useful method for managers to explore the impacts of different fishing and fleet management strategies for the future.

Connecting Groundwater, Crop Price, and Crop Production Variability in India

NASA Astrophysics Data System (ADS)

Pollack, A.; Lobell, D. B.; Jain, M.

2015-12-01

Farmers in India rely on groundwater resources for irrigation and production of staple crops that provide over half of the calories consumed domestically each year. While this has been a productive strategy in increasing agricultural production and maintaining high yields, groundwater resources are depleting at a quicker rate than natural resources can replace. This issue gains relevance as climate variability concurrently adds to yearly fluctuations in farmer demand for irrigation each year, which can create high risk for farmers that depend on consistent yields, but do not have access to dwindling water resources. This study investigates variability in groundwater levels from 2005 to 2013 in relation to crop prices and production by analyzing district-level datasets made available through India's government. Through this analysis, we show the impact of groundwater variability on price variability, crop yield, and production during these years. By examining this nine-year timescale, we extend our analysis to forthcoming years to demonstrate the increasing importance of groundwater resources in irrigation, and suggest strategies to reduce the impact of groundwater shortages on crop production and prices.

Genetic variability in captive populations of the stingless bee Tetragonisca angustula.

PubMed

Santiago, Leandro R; Francisco, Flávio O; Jaffé, Rodolfo; Arias, Maria C

2016-08-01

Low genetic variability has normally been considered a consequence of animal husbandry and a major contributing factor to declining bee populations. Here, we performed a molecular analysis of captive and wild populations of the stingless bee Tetragonisca angustula, one of the most commonly kept species across South America. Microsatellite analyses showed similar genetic variability between wild and captive populations However, captive populations showed lower mitochondrial genetic variability. Male-mediated gene flow, transport and division of nests are suggested as the most probable explanations for the observed patterns of genetic structure. We conclude that increasing the number of colonies kept through nest divisions does not negatively affect nuclear genetic variability, which seems to be maintained by small-scale male dispersal and human-mediated nest transport. However, the transport of nests from distant localities should be practiced with caution given the high genetic differentiation observed between samples from western and eastern areas. The high genetic structure verified is the result of a long-term evolutionary process, and bees from distant localities may represent unique evolutionary lineages.

High variability impairs motor learning regardless of whether it affects task performance.

PubMed

Cardis, Marco; Casadio, Maura; Ranganathan, Rajiv

2018-01-01

Motor variability plays an important role in motor learning, although the exact mechanisms of how variability affects learning are not well understood. Recent evidence suggests that motor variability may have different effects on learning in redundant tasks, depending on whether it is present in the task space (where it affects task performance) or in the null space (where it has no effect on task performance). We examined the effect of directly introducing null and task space variability using a manipulandum during the learning of a motor task. Participants learned a bimanual shuffleboard task for 2 days, where their goal was to slide a virtual puck as close as possible toward a target. Critically, the distance traveled by the puck was determined by the sum of the left- and right-hand velocities, which meant that there was redundancy in the task. Participants were divided into five groups, based on both the dimension in which the variability was introduced and the amount of variability that was introduced during training. Results showed that although all groups were able to reduce error with practice, learning was affected more by the amount of variability introduced rather than the dimension in which variability was introduced. Specifically, groups with higher movement variability during practice showed larger errors at the end of practice compared with groups that had low variability during learning. These results suggest that although introducing variability can increase exploration of new solutions, this may adversely affect the ability to retain the learned solution. NEW & NOTEWORTHY We examined the role of introducing variability during motor learning in a redundant task. The presence of redundancy allows variability to be introduced in different dimensions: the task space (where it affects task performance) or the null space (where it does not affect task performance). We found that introducing variability affected learning adversely, but the amount of variability was more critical than the dimension in which variability was introduced.

Cognitive Performance and Heart Rate Variability: The Influence of Fitness Level

PubMed Central

Luque-Casado, Antonio; Zabala, Mikel; Morales, Esther; Mateo-March, Manuel; Sanabria, Daniel

2013-01-01

In the present study, we investigated the relation between cognitive performance and heart rate variability as a function of fitness level. We measured the effect of three cognitive tasks (the psychomotor vigilance task, a temporal orienting task, and a duration discrimination task) on the heart rate variability of two groups of participants: a high-fit group and a low-fit group. Two major novel findings emerged from this study. First, the lowest values of heart rate variability were found during performance of the duration discrimination task, compared to the other two tasks. Second, the results showed a decrement in heart rate variability as a function of the time on task, although only in the low-fit group. Moreover, the high-fit group showed overall faster reaction times than the low-fit group in the psychomotor vigilance task, while there were not significant differences in performance between the two groups of participants in the other two cognitive tasks. In sum, our results highlighted the influence of cognitive processing on heart rate variability. Importantly, both behavioral and physiological results suggested that the main benefit obtained as a result of fitness level appeared to be associated with processes involving sustained attention. PMID:23437276

Navigation bronchoscopy for diagnosis and small nodule location

PubMed Central

Muñoz-Largacha, Juan A.; Litle, Virginia R.

2017-01-01

Lung cancer continues to be the most common cause of cancer death. Screening programs for high risk patients with the use of low-dose computed tomography (CT) has led to the identification of small lung lesions that were difficult to identify using previous imaging modalities. Electromagnetic navigational bronchoscopy (ENB) is a novel technique that has shown to be of great utility during the evaluation of small, peripheral lesions, that would otherwise be challenging to evaluate with conventional bronchoscopy. The diagnostic yield of navigational bronchoscopy however is highly variable, with reports ranging from 59% to 94%. This variability suggests that well-defined selection criteria and standardized protocols for the use of ENB are lacking. Despite this variability, we believe that this technique is a useful tool evaluating small peripheral lung lesions when patients are properly selected. PMID:28446971

Climate variability and extremes, interacting with nitrogen storage, amplify eutrophication risk

USGS Publications Warehouse

Lee, Minjin; Shevliakova, Elena; Malyshev, Sergey; Milly, P.C.D.; Jaffe, Peter R.

2016-01-01

Despite 30 years of basin-wide nutrient-reduction efforts, severe hypoxia continues to be observed in the Chesapeake Bay. Here we demonstrate the critical influence of climate variability, interacting with accumulated nitrogen (N) over multidecades, on Susquehanna River dissolved nitrogen (DN) loads, known precursors of the hypoxia in the Bay. We used the process model LM3-TAN (Terrestrial and Aquatic Nitrogen), which is capable of capturing both seasonal and decadal-to-century changes in vegetation-soil-river N storage, and produced nine scenarios of DN-load distributions under different short-term scenarios of climate variability and extremes. We illustrate that after 1 to 3 yearlong dry spells, the likelihood of exceeding a threshold DN load (56 kt yr−1) increases by 40 to 65% due to flushing of N accumulated throughout the dry spells and altered microbial processes. Our analyses suggest that possible future increases in climate variability/extremes—specifically, high precipitation occurring after multiyear dry spells—could likely lead to high DN-load anomalies and hypoxia.

External Catalyst Breakup Phenomena

DTIC Science & Technology

1975-09-01

thruster exposure. a Erosion .by a pulsed liquid stream at high velocity. * Thermal shock from liquid quench cooldovn. 9 Erosion resulting from solid...the liquid velocity. During a cold start contact with hydrazine leading to liquid wetting can lead to very high internal pressures as a result ot the...compression and final dilation, suggest benefits from reducing this variable. A . Isolating the catalyst particles from one another so as to avoid high

Reduction in spread of excitation from current focusing at multiple cochlear locations in cochlear implant users.

PubMed

Padilla, Monica; Landsberger, David M

2016-03-01

Channel interaction from a broad spread of excitation is likely to be a limiting factor in performance by cochlear implant users. Although partial tripolar stimulation has been shown to reduce spread of excitation, the magnitude of the reduction is highly variable across subjects. Because the reduction in spread of excitation is typically only measured at one electrode for a given subject, the degree of variability across cochlear locations is unknown. The first goal of the present study was to determine if the reduction in spread of excitation observed from partial tripolar current focusing systematically varies across the cochlea. The second goal was to measure the variability in reduction of spread of excitation relative to monopolar stimulation across the cochlea. The third goal was to expand upon previous results that suggest that scaling of verbal descriptors can be used to predict the reduction in spread of excitation, by increasing the limited number of sites previously evaluated and verify the relationships remain with the larger dataset. The spread of excitation for monopolar and partial tripolar stimulation was measured at 5 cochlear locations using a psychophysical forward masking task. Results of the present study suggest that although partial tripolar stimulation typically reduces spread of excitation, the degree of reduction in spread of excitation was found to be highly variable and no effect of cochlear location was found. Additionally, subjective scaling of certain verbal descriptors (Clean/Dirty, Pure/Noisy) correlated with the reduction in spread of excitation suggesting sound quality scaling might be used as a quick clinical estimate of channels providing a reduction in spread of excitation. This quick scaling technique might help clinicians determine which patients would be most likely to benefit from a focused strategy. Copyright © 2016 Elsevier B.V. All rights reserved.

Reduction in Spread of Excitation from Current Focusing at Multiple Cochlear Locations in Cochlear Implant Users

PubMed Central

Padilla, Monica; Landsberger, David M.

2016-01-01

Channel interaction from a broad spread of excitation is likely to be a limiting factor in performance by cochlear implant users. Although partial tripolar stimulation has been shown to reduce spread of excitation, the magnitude of the reduction is highly variable across subjects. Because the reduction in spread of excitation is typically only measured at one electrode for a given subject, the degree of variability across cochlear locations is unknown. The first goal of the present study was to determine if the reduction in spread of excitation observed from partial tripolar current focusing systematically varies across the cochlea. The second goal was to measure the variability in reduction of spread of excitation relative to monopolar stimulation across the cochlea. The third goal was to expand upon previous results that suggest that scaling of verbal descriptors can be used to predict the reduction in spread of excitation, by increasing the limited number of sites previously evaluated and verify the relationships remain with the larger dataset. The spread of excitation for monopolar and partial tripolar stimulation was measured at 5 cochlear locations using a psychophysical forward masking task. Results of the present study suggest that although partial tripolar stimulation typically reduces spread of excitation, the degree of reduction in spread of excitation was found to be highly variable and no effect of cochlear location was found. Additionally, subjective scaling of certain verbal descriptors (Clean/Dirty, Pure/Noisy) correlated with the reduction in spread of excitation suggesting sound quality scaling might be used as a quick clinical estimate of channels providing a reduction in spread of excitation. This quick scaling technique might help clinicians determine which patients would be most likely to benefit from a focused strategy. PMID:26778546

Time-Variable Transit Time Distributions in the Hyporheic Zone of a Headwater Mountain Stream

NASA Astrophysics Data System (ADS)

Ward, Adam S.; Schmadel, Noah M.; Wondzell, Steven M.

2018-03-01

Exchange of water between streams and their hyporheic zones is known to be dynamic in response to hydrologic forcing, variable in space, and to exist in a framework with nested flow cells. The expected result of heterogeneous geomorphic setting, hydrologic forcing, and between-feature interaction is hyporheic transit times that are highly variable in both space and time. Transit time distributions (TTDs) are important as they reflect the potential for hyporheic processes to impact biogeochemical transformations and ecosystems. In this study we simulate time-variable transit time distributions based on dynamic vertical exchange in a headwater mountain stream with observed, heterogeneous step-pool morphology. Our simulations include hyporheic exchange over a 600 m river corridor reach driven by continuously observed, time-variable hydrologic conditions for more than 1 year. We found that spatial variability at an instance in time is typically larger than temporal variation for the reach. Furthermore, we found reach-scale TTDs were marginally variable under all but the most extreme hydrologic conditions, indicating that TTDs are highly transferable in time. Finally, we found that aggregation of annual variation in space and time into a "master TTD" reasonably represents most of the hydrologic dynamics simulated, suggesting that this aggregation approach may provide a relevant basis for scaling from features or short reaches to entire networks.

Investigation of clinical pharmacokinetic variability of an opioid antagonist through physiologically based absorption modeling.

PubMed

Ding, Xuan; He, Minxia; Kulkarni, Rajesh; Patel, Nita; Zhang, Xiaoyu

2013-08-01

Identifying the source of inter- and/or intrasubject variability in pharmacokinetics (PK) provides fundamental information in understanding the pharmacokinetics-pharmacodynamics relationship of a drug and project its efficacy and safety in clinical populations. This identification process can be challenging given that a large number of potential causes could lead to PK variability. Here we present an integrated approach of physiologically based absorption modeling to investigate the root cause of unexpectedly high PK variability of a Phase I clinical trial drug. LY2196044 exhibited high intersubject variability in the absorption phase of plasma concentration-time profiles in humans. This could not be explained by in vitro measurements of drug properties and excellent bioavailability with low variability observed in preclinical species. GastroPlus™ modeling suggested that the compound's optimal solubility and permeability characteristics would enable rapid and complete absorption in preclinical species and in humans. However, simulations of human plasma concentration-time profiles indicated that despite sufficient solubility and rapid dissolution of LY2196044 in humans, permeability and/or transit in the gastrointestinal (GI) tract may have been negatively affected. It was concluded that clinical PK variability was potentially due to the drug's antagonism on opioid receptors that affected its transit and absorption in the GI tract. Copyright © 2013 Wiley Periodicals, Inc.

An examination of variables which influence high school students to enroll in an undergraduate engineering or physical science major

NASA Astrophysics Data System (ADS)

Porter, Christopher H.

The purpose of this study was to examine the variables which influence a high school student to enroll in an engineering discipline versus a physical science discipline. Data was collected utilizing the High School Activities, Characteristics, and Influences Survey, which was administered to students who were freshmen in an engineering or physical science major at an institution in the Southeastern United States. A total of 413 students participated in the survey. Collected data were analyzed using descriptive statistics, two-sample Wilcoxon tests, and binomial logistic regression techniques. A total of 29 variables were deemed significant between the general engineering and physical science students. The 29 significant variables were further analyzed to see which have an independent impact on a student to enroll in an undergraduate engineering program, as opposed to an undergraduate physical science program. Four statistically significant variables were found to have an impact on a student's decision to enroll in a engineering undergraduate program versus a physical science program: father's influence, participation in Project Lead the Way, and the subjects of mathematics and physics. Recommendations for theory, policy, and practice were discussed based on the results of the study. This study presented suggestions for developing ways to attract, educate, and move future engineers into the workforce.

Spatial heterogeneity of within-stream methane concentrations

USGS Publications Warehouse

Crawford, John T.; Loken, Luke C.; West, William E.; Crary, Benjamin; Spawn, Seth A.; Gubbins, Nicholas; Jones, Stuart E.; Striegl, Robert G.; Stanley, Emily H.

2017-01-01

Streams, rivers, and other freshwater features may be significant sources of CH4 to the atmosphere. However, high spatial and temporal variabilities hinder our ability to understand the underlying processes of CH4 production and delivery to streams and also challenge the use of scaling approaches across large areas. We studied a stream having high geomorphic variability to assess the underlying scale of CH4 spatial variability and to examine whether the physical structure of a stream can explain the variation in surface CH4. A combination of high-resolution CH4 mapping, a survey of groundwater CH4 concentrations, quantitative analysis of methanogen DNA, and sediment CH4 production potentials illustrates the spatial and geomorphic controls on CH4 emissions to the atmosphere. We observed significant spatial clustering with high CH4 concentrations in organic-rich stream reaches and lake transitions. These sites were also enriched in the methane-producing mcrA gene and had highest CH4 production rates in the laboratory. In contrast, mineral-rich reaches had significantly lower concentrations and had lesser abundances of mcrA. Strong relationships between CH4and the physical structure of this aquatic system, along with high spatial variability, suggest that future investigations will benefit from viewing streams as landscapes, as opposed to ecosystems simply embedded in larger terrestrial mosaics. In light of such high spatial variability, we recommend that future workers evaluate stream networks first by using similar spatial tools in order to build effective sampling programs.

A remarkable oxygen-rich asymptotic giant branch variable in the Sagittarius Dwarf Irregular Galaxy

NASA Astrophysics Data System (ADS)

Whitelock, Patricia A.; Menzies, John W.; Feast, Michael W.; Marigo, Paola

2018-01-01

We report and discuss JHKS photometry for Sgr dIG, a very metal-deficient galaxy in the Local Group, obtained over 3.5 years with the Infrared Survey Facility in South Africa. Three large amplitude asymptotic giant branch variables are identified. One is an oxygen-rich star that has a pulsation period of 950 d, which was until recently undergoing hot bottom burning, with Mbol ∼ -6.7. It is surprising to find a variable of this sort in Sgr dIG, given their rarity in other dwarf irregulars. Despite its long period the star is relatively blue and is fainter, at all wavelengths shorter than 4.5 μm, than anticipated from period-luminosity relations that describe hot bottom burning stars. A comparison with models suggests it had a main-sequence mass Mi ∼ 5 M⊙ and that it is now near the end of its asymptotic giant branch evolution. The other two periodic variables are carbon stars with periods of 670 and 503 d (Mbol ∼ -5.7 and -5.3). They are very similar to other such stars found on the asymptotic giant branch of metal-deficient Local Group galaxies and a comparison with models suggests Mi ∼ 3 M⊙. We compare the number of asymptotic giant branch variables in Sgr dIG to those in NGC 6822 and IC 1613, and suggest that the differences may be due to the high specific star formation rate and low metallicity of Sgr dIG.

Climate change but not unemployment explains the changing suicidality in Thessaloniki Greece (2000-2012).

PubMed

Fountoulakis, Konstantinos N; Savopoulos, Christos; Zannis, Prodromos; Apostolopoulou, Martha; Fountoukidis, Ilias; Kakaletsis, Nikolaos; Kanellos, Ilias; Dimellis, Dimos; Hyphantis, Thomas; Tsikerdekis, Athanasios; Pompili, Maurizio; Hatzitolios, Apostolos I

2016-03-15

Recently there was a debate concerning the etiology behind attempts and completed suicides. The aim of the current study was to search for possible correlations between the rates of attempted and completed suicide and climate variables and regional unemployment per year in the county of Thessaloniki, Macedonia, northern Greece, for the years 2000-12. The regional rates of suicide and attempted suicide as well as regional unemployment were available from previous publications of the authors. The climate variables were calculated from the daily E-OBS gridded dataset which is based on observational data Only the male suicide rates correlate significantly with high mean annual temperature but not with unemployment. The multiple linear regression analysis results suggest that temperature is the only variable that determines male suicides and explains 51% of their variance. Unemployment fails to contribute significantly to the model. There seems to be a seasonal distribution for attempts with mean rates being higher for the period from May to October and the rates clearly correlate with temperature. The highest mean rates were observed during May and August and the lowest during December and February. Multiple linear regression analysis suggests that temperature also determines the female attempts rate although the explained variable is significant but very low (3-5%) Climate variables and specifically high temperature correlate both with suicide and attempted suicide rates but with a different way between males and females. The climate effect was stronger than the effect of unemployment. Copyright © 2016 Elsevier B.V. All rights reserved.

When is affect variability bad for health? The association between affect variability and immune response to the influenza vaccination.

PubMed

Jenkins, Brooke N; Hunter, John F; Cross, Marie P; Acevedo, Amanda M; Pressman, Sarah D

2018-01-01

This study addresses methodological and theoretical questions about the association between affect and physical health. Specifically, we examine the role of affect variability and its interaction with mean levels of affect to predict antibody (Ab) levels in response to an influenza vaccination. Participants (N=83) received the vaccination and completed daily diary measures of affect four times a day for 13days. At one and four months post-vaccination, blood was collected from the participants to assess Ab levels. Findings indicate that affect variability and its interaction with mean levels of affect predict an individual's immune response. Those high in mean positive affect (PA) who had more PA variability were more likely to have a lower Ab response in comparison to those who had high mean PA and less PA variability. Although it did not interact with mean negative affect (NA), NA variability on its own was associated with Ab response, whereby those with less NA variability mounted a more robust immune response. Affect variability is related to immune response to an influenza vaccination and, in some cases, interacts with mean levels of affect. These oscillations in affective experiences are critical to consider in order to unpack the intricacies of how affect influences health. These findings suggest that future researchers should consider the important role of affect variability on physical health-relevant outcomes as well as examine the moderating effect of mean affect levels. Copyright © 2017 Elsevier Inc. All rights reserved.

High levels of diversity characterize mandrill (Mandrillus sphinx) Mhc-DRB sequences.

PubMed

Abbott, Kristin M; Wickings, E Jean; Knapp, Leslie A

2006-08-01

The major histocompatibility complex (MHC) is highly polymorphic in most primate species studied thus far. The rhesus macaque (Macaca mulatta) has been studied extensively and the Mhc-DRB region demonstrates variability similar to humans. The extent of MHC diversity is relatively unknown for other Old World monkeys (OWM), especially among genera other than Macaca. A molecular survey of the Mhc-DRB region in mandrills (Mandrillus sphinx) revealed extensive variability, suggesting that other OWMs may also possess high levels of Mhc-DRB polymorphism. In the present study, 33 Mhc-DRB loci were identified from only 13 animals. Eleven were wild-born and presumed to be unrelated and two were captive-born twins. Two to seven different sequences were identified for each individual, suggesting that some mandrills may have as many as four Mhc-DRB loci on a single haplotype. From these sequences, representatives of at least six Mhc-DRB loci or lineages were identified. As observed in other primates, some new lineages may have arisen through the process of gene conversion. These findings indicate that mandrills have Mhc-DRB diversity not unlike rhesus macaques and humans.

Mindfulness and heart rate variability in individuals with high and low generalized anxiety symptoms.

PubMed

Mankus, Annette M; Aldao, Amelia; Kerns, Caroline; Mayville, Elena Wright; Mennin, Douglas S

2013-07-01

Mindfulness has been incorporated into several treatment approaches for psychopathology. Despite the popularity of this approach, relatively few empirical investigations have examined the relationship between mindfulness and autonomic indicators of flexible emotion regulation, such as heart rate variability (HRV). Generalized anxiety disorder (GAD) has been associated with both low levels of mindfulness and HRV. In this investigation, we examined the relationship between HRV and mindfulness in the context of elevated generalized anxiety (GA) symptoms--an analog for GAD--by examining whether GA level moderated this relationship. HRV was collected while participants completed self-report measures of GA and trait mindfulness. GA level interacted with mindfulness in the prediction of HRV; in the high GA, but not low GA group, mindfulness was positively associated with HRV. This suggests that for individuals with high GA, mindfulness may enhance parasympathetic influences on the heart rate. We address the limitations of the current investigation and suggest avenues for future research on mindfulness-related changes in tonic and phasic HRV over time. Copyright © 2013 Elsevier Ltd. All rights reserved.

Impact of advanced monitoring variables on intraoperative clinical decision-making: an international survey.

PubMed

Joosten, Alexandre; Desebbe, Olivier; Suehiro, Koichi; Essiet, Mfonobong; Alexander, Brenton; Ricks, Cameron; Rinehart, Joseph; Faraoni, David; Cecconi, Maurizio; Van der Linden, Philippe; Cannesson, Maxime

2017-02-01

To assess the relationship between the addition of advanced monitoring variables and changes in clinical decision-making. A 15-questions survey was anonymously emailed to international experts and physician members of five anesthesia societies which focused on assessing treatment decisions of clinicians during three realistic clinical scenarios measured at two distinct time points. The first is when typical case information and basic monitoring (T1) were provided, and then once again after the addition of advanced monitoring variables (T2). We hypothesized that the addition of advanced variables would increase the incidence of an optimal therapeutic decision (a priori defined as the answer with the highest percentage of expert agreement) and decrease the variability among the physician's suggested treatments. The survey was completed by 18 experts and 839 physicians. Overall, adding advanced monitoring did not significantly increase physician response accuracy, with the least substantial changes noted on questions related to volume expansion or vasopressor administration. Moreover, advanced monitoring data did not significantly decrease the high level of initial practice variability in physician suggested treatments (P = 0.13), in contrast to the low variability observed within the expert group (P = 0.039). Additionally, 5-10 years of practice (P < 0.0001) and a cardiovascular subspecialty (P = 0.048) were both physician characteristics associated with a higher rate of optimal therapeutic decisions. The addition of advanced variables was of limited benefit for most physicians, further indicating the need for more in depth education on the clinical value and technical understanding of such variables.

Emergence of context-dependent variability across a basal ganglia network.

PubMed

Woolley, Sarah C; Rajan, Raghav; Joshua, Mati; Doupe, Allison J

2014-04-02

Context dependence is a key feature of cortical-basal ganglia circuit activity, and in songbirds the cortical outflow of a basal ganglia circuit specialized for song, LMAN, shows striking increases in trial-by-trial variability and bursting when birds sing alone rather than to females. To reveal where this variability and its social regulation emerge, we recorded stepwise from corticostriatal (HVC) neurons and their target spiny and pallidal neurons in Area X. We find that corticostriatal and spiny neurons both show precise singing-related firing across both social settings. Pallidal neurons, in contrast, exhibit markedly increased trial-by-trial variation when birds sing alone, created by highly variable pauses in firing. This variability persists even when recurrent inputs from LMAN are ablated. These data indicate that variability and its context sensitivity emerge within the basal ganglia network, suggest a network mechanism for this emergence, and highlight variability generation and regulation as basal ganglia functions. Copyright © 2014 Elsevier Inc. All rights reserved.

Emergence of context-dependent variability across a basal ganglia network

PubMed Central

Woolley, Sarah C.; Rajan, Raghav; Joshua, Mati; Doupe, Allison J.

2014-01-01

Summary Context-dependence is a key feature of cortical-basal ganglia circuit activity, and in songbirds, the cortical outflow of a basal ganglia circuit specialized for song, LMAN, shows striking increases in trial-by-trial variability and bursting when birds sing alone rather than to females. To reveal where this variability and its social regulation emerge, we recorded stepwise from cortico-striatal (HVC) neurons and their target spiny and pallidal neurons in Area X. We find that cortico-striatal and spiny neurons both show precise singing-related firing across both social settings. Pallidal neurons, in contrast, exhibit markedly increased trial-by-trial variation when birds sing alone, created by highly variable pauses in firing. This variability persists even when recurrent inputs from LMAN are ablated. These data indicate that variability and its context-sensitivity emerge within the basal ganglia network, suggest a network mechanism for this emergence, and highlight variability generation and regulation as basal ganglia functions. PMID:24698276

Poisson-Like Spiking in Circuits with Probabilistic Synapses

PubMed Central

Moreno-Bote, Rubén

2014-01-01

Neuronal activity in cortex is variable both spontaneously and during stimulation, and it has the remarkable property that it is Poisson-like over broad ranges of firing rates covering from virtually zero to hundreds of spikes per second. The mechanisms underlying cortical-like spiking variability over such a broad continuum of rates are currently unknown. We show that neuronal networks endowed with probabilistic synaptic transmission, a well-documented source of variability in cortex, robustly generate Poisson-like variability over several orders of magnitude in their firing rate without fine-tuning of the network parameters. Other sources of variability, such as random synaptic delays or spike generation jittering, do not lead to Poisson-like variability at high rates because they cannot be sufficiently amplified by recurrent neuronal networks. We also show that probabilistic synapses predict Fano factor constancy of synaptic conductances. Our results suggest that synaptic noise is a robust and sufficient mechanism for the type of variability found in cortex. PMID:25032705

Oxygen isotope and trace element compositions of platiniferous dunite pipes of the Bushveld Complex, South Africa - Signals from a recycled mantle component?

NASA Astrophysics Data System (ADS)

Günther, T.; Haase, K. M.; Junge, M.; Oberthür, T.; Woelki, D.; Krumm, S.

2018-06-01

Platiniferous dunite pipes occur in the lower mafic/ultramafic portion of the Rustenburg Layered Suite of the Bushveld large igneous province (LIP). Olivine compositions in these pipes range from forsterite (Fo) 80 to 35 mol% and suggest crystallization from variably evolved magmas at high temperatures ( 1200 °C). The most primitive olivines are from a stock unit and have the highest contents of Ni (>0.15 wt%) and lowest contents of Mn (<0.3 wt%). Fractional crystallization and partial melting of pyroxenite host rock play a significant role in the formation of the fayalitic olivines with its high Mn contents (>0.3 wt%). High δ18O values of olivine (5.7-7.0‰) and pyroxene (6.7-7.4‰) are akin to those of the Lower and Critical Zone of the Bushveld intrusion suggesting a common origin. The constant high O isotope ratios with variable Fo contents in the olivines are unlike trends observed in olivine phenocrysts in magmas forming by assimilation-fractional crystallization. We suggest that the high δ18O in the most primitive dunites reflect that of the primary melt of the Bushveld pipes, indicating either a bulk assimilation of crust prior to pipe formation or a contribution from recycled oceanic crust in the sub-continental lithospheric mantle (SCLM). The latter scenario is supported by the high Ni/Mn ratios in primitive pipe olivine that might be inherited from melting of a pyroxene-rich mantle source.

Animal escapology II: escape trajectory case studies

PubMed Central

Domenici, Paolo; Blagburn, Jonathan M.; Bacon, Jonathan P.

2011-01-01

Summary Escape trajectories (ETs; measured as the angle relative to the direction of the threat) have been studied in many taxa using a variety of methodologies and definitions. Here, we provide a review of methodological issues followed by a survey of ET studies across animal taxa, including insects, crustaceans, molluscs, lizards, fish, amphibians, birds and mammals. Variability in ETs is examined in terms of ecological significance and morpho-physiological constraints. The survey shows that certain escape strategies (single ETs and highly variable ETs within a limited angular sector) are found in most taxa reviewed here, suggesting that at least some of these ET distributions are the result of convergent evolution. High variability in ETs is found to be associated with multiple preferred trajectories in species from all taxa, and is suggested to provide unpredictability in the escape response. Random ETs are relatively rare and may be related to constraints in the manoeuvrability of the prey. Similarly, reports of the effect of refuges in the immediate environment are relatively uncommon, and mainly confined to lizards and mammals. This may be related to the fact that work on ETs carried out in laboratory settings has rarely provided shelters. Although there are a relatively large number of examples in the literature that suggest trends in the distribution of ETs, our understanding of animal escape strategies would benefit from a standardization of the analytical approach in the study of ETs, using circular statistics and related tests, in addition to the generation of large data sets. PMID:21753040

Origin and distribution of Sporothrix globosa causing sapronoses in Asia.

PubMed

Moussa, Tarek A A; Kadasa, Naif M S; Al Zahrani, Hassan S; Ahmed, Sarah Abdallah; Feng, Peiying; Gerrits van den Ende, Albertus H G; Zhang, Yu; Kano, Rui; Li, Fuqiu; Li, Shanshan; Song, Yang; Dong, Bilin; Rossato, Luana; Dolatabadi, Somayeh; Hoog, Sybren de

2017-05-01

The aim of the study was to evaluate the main sources and epidemiological patterns and speculate on the evolutionary origin of Sporothrix globosa in Asia. Case and case series literature on sporotrichosis in Asia from January 2007 onwards were reviewed using meta-analysis. Phylogenetic analysis of relevant S. globosa was carried out on the basis of concatenated sequences of ITS, TEF3 and CAL. A haplotype network of CAL sequences of 281 Sporothrix isolates was analysed to determine the population structure of S. globosa. Nearly all cases of sporotrichosis caused by S. globosa in Asia were human. In contrast to the remaining pathogenic Sporothrix species, feline transmission was exceptional; nearly all regional cat-associated cases were caused by Sporothrix schenckii. While the latter species was highly variable and showed recombination, S. globosa seemed to be a clonal offshoot, as was Sporothrix brasiliensis. The origin of the segregants was located in an area of high variability in S. schenckii with a relatively high frequency of Asian strains. In Asia, S. globosa was the prevalent species. The low diversity of S. globosa suggested a recent divergence with a founder effect of low variability from the variable ancestral species, S. schenckii.

The role of connectivity and hydrodynamic conditions in the configuration of ichthyoplankton assemblages in coastal lagoons

NASA Astrophysics Data System (ADS)

Pérez-Ruzafa, Angel; Quispe, Jhoni I.; Umgiesser, Georg; Ghezzo, Michol; De Pascalis, Francesca; Marcos, Concepción

2014-05-01

Fish assemblages in coastal lagoons are constituted by species with different gilds and life stories including estuarine residents but also a high percentage of marine stragglers and marine migrants. Previous studies showed that different ichthyoplancton assemblages can be identified inside a lagoon, depending on hydrological conditions, but at the same time a high spatial and temporal variability haven observed. The proposed models to explain lagoon assemblages configuration based on probabilities of colonization from the open sea involves an important stochastic component and introduces some randomness that could lead to that high spatial and temporal variability at short and long-term scales. In this work we analyze the relationship between ichthyoplankton assemblages in the Mar Menor lagoon and the adjacent open sea in the framework of the hydrodynamics of the lagoon and connectivity between sampling stations using hydrodynamic models. The results, show a complex interaction between the different factors that lead to a highly variable system with high accumulated richness and diversity of species, and a large proportion of occasional visitors and stragglers suggesting that the mechanisms of competitive lottery can play an important role in the maintenance of communities of coastal lagoons , where environmental variability occurs in a system with strong differences in colonization rates and connectivity, not only with the open sea, but also between locations within the lagoon.

Potential sources of variability in mesocosm experiments on the response of phytoplankton to ocean acidification

NASA Astrophysics Data System (ADS)

Moreno de Castro, Maria; Schartau, Markus; Wirtz, Kai

2017-04-01

Mesocosm experiments on phytoplankton dynamics under high CO2 concentrations mimic the response of marine primary producers to future ocean acidification. However, potential acidification effects can be hindered by the high standard deviation typically found in the replicates of the same CO2 treatment level. In experiments with multiple unresolved factors and a sub-optimal number of replicates, post-processing statistical inference tools might fail to detect an effect that is present. We propose that in such cases, data-based model analyses might be suitable tools to unearth potential responses to the treatment and identify the uncertainties that could produce the observed variability. As test cases, we used data from two independent mesocosm experiments. Both experiments showed high standard deviations and, according to statistical inference tools, biomass appeared insensitive to changing CO2 conditions. Conversely, our simulations showed earlier and more intense phytoplankton blooms in modeled replicates at high CO2 concentrations and suggested that uncertainties in average cell size, phytoplankton biomass losses, and initial nutrient concentration potentially outweigh acidification effects by triggering strong variability during the bloom phase. We also estimated the thresholds below which uncertainties do not escalate to high variability. This information might help in designing future mesocosm experiments and interpreting controversial results on the effect of acidification or other pressures on ecosystem functions.

An oilspill trajectory analysis model with a variable wind deflection angle

USGS Publications Warehouse

Samuels, W.B.; Huang, N.E.; Amstutz, D.E.

1982-01-01

The oilspill trajectory movement algorithm consists of a vector sum of the surface drift component due to wind and the surface current component. In the U.S. Geological Survey oilspill trajectory analysis model, the surface drift component is assumed to be 3.5% of the wind speed and is rotated 20 degrees clockwise to account for Coriolis effects in the Northern Hemisphere. Field and laboratory data suggest, however, that the deflection angle of the surface drift current can be highly variable. An empirical formula, based on field observations and theoretical arguments relating wind speed to deflection angle, was used to calculate a new deflection angle at each time step in the model. Comparisons of oilspill contact probabilities to coastal areas calculated for constant and variable deflection angles showed that the model is insensitive to this changing angle at low wind speeds. At high wind speeds, some statistically significant differences in contact probabilities did appear. ?? 1982.

Assessment of chlorophyll variability along the northwestern coast of Iberian Peninsula

NASA Astrophysics Data System (ADS)

Picado, A.; Alvarez, I.; Vaz, N.; Varela, R.; Gomez-Gesteira, M.; Dias, J. M.

2014-10-01

The northwestern coast of the Iberian Peninsula is characterized by a high primary production mainly supported by coastal upwelling, creating an extraordinary commercial interest for fisheries and aquaculture. Considering chlorophyll-a (Chl-a) as an indicator of primary production, its spatio-temporal variability was researched in this study in the surface water of this upwelling region from 1998 to 2007. Satellite derived Chl-a, Sea Surface Temperature (SST) and Ekman transport data as well as the inflow of the main rivers discharging into the study area were used to investigate the origin of the Chl-a concentration. Empirical Orthogonal Function (EOF) analysis of weekly Chl-a images was performed, as well as correlation analysis between Chl-a concentration, Ekman transport and river discharge. EOF results suggest that the highest Chl-a concentration occurs near the coast up to 60 km offshore. The interannual variability of Chl-a, SST and Ekman transport was also studied considering summer and winter months. Generally, 2005, 2006 and 2007 were the most productive years during the summer months with high Chl-a concentrations along the coast associated to the strong upwelling conditions observed. Otherwise, 1998 seemed to be the most productive year during winter. The absence of upwelling favorable conditions together with localized low SST and considerable discharges, suggests that the high Chl-a concentrations observed during this period are mainly due to the entrance of nutrients through river runoff. However, in winter, high concentrations of colored dissolved organic matter (CDOM), associated with river runoff, are present in the ocean surface, leading to an erroneous strong signal of the satellite. During winter correlations of 0.58 and 0.49 were found between Chl-a concentration and Douro and Minho discharges, respectively, evidencing that high Chl-a concentration was related with river runoff. Otherwise, during summer, Chl-a and Ekman transport exhibited a correlation of - 0.38 indicating that high Chl-a is associated to upwelling events. In summary, it was found that the spatio-temporal variability of Chl-a along the northwestern coast of Iberian Peninsula exhibited the clear influence of upwelling events during summer. Conversely, the variability during winter was mainly due to entrance of nutrients through the rivers discharge which flow into the area.

Gratitude is Associated with Greater Levels of Protective Factors and Lower Levels of Risks in African American Adolescents

PubMed Central

Ma, Mindy; Kibler, Jeffrey L.; Sly, Kaye

2013-01-01

The literature suggests gratitude is associated with positive youth development. The current study examined the relationship between gratitude and protective/risk factors among African American youth. Adolescents (N = 389; 50.4% males) ages 12 – 14 completed measures of gratitude (moral affect and life-orientation), protective factors (e.g., academic and activity engagement, family relationship), and high-risk behaviors (e.g., sexual attitudes and behaviors, drug/alcohol use). Results indicated greater moral affect gratitude was the only variable significantly associated with greater academic interest, better academic performance, and more extra-curricular activity engagement. Greater moral affect and life-orientation gratitude both significantly correlated with positive family relationship. Greater life-orientation gratitude was the only variable significantly associated with abstinence from sexual intimacy, sexual intercourse, likelihood of engaging in sex during primary school, and abstinence from drug/alcohol use. The findings suggest that moral affect gratitude may enhance protective factors while life-orientation gratitude may buffer against high-risk behaviors among African American youth. PMID:24011114

Making stronger causal inferences: Accounting for selection bias in associations between high performance work systems, leadership, and employee and customer satisfaction.

PubMed

Schmidt, Joseph A; Pohler, Dionne M

2018-05-17

We develop competing hypotheses about the relationship between high performance work systems (HPWS) with employee and customer satisfaction. Drawing on 8 years of employee and customer survey data from a financial services firm, we used a recently developed empirical technique-covariate balanced propensity score (CBPS) weighting-to examine if the proposed relationships between HPWS and satisfaction outcomes can be explained by reverse causality, selection effects, or commonly omitted variables such as leadership behavior. The results provide support for leader behaviors as a primary driver of customer satisfaction, rather than HPWS, and also suggest that the problem of reverse causality requires additional attention in future human resource (HR) systems research. Model comparisons suggest that the estimates and conclusions vary across CBPS, meta-analytic, cross-sectional, and time-lagged models (with and without a lagged dependent variable as a control). We highlight the theoretical and methodological implications of the findings for HR systems research. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

High sequence variability among hemocyte-specific Kazal-type proteinase inhibitors in decapod crustaceans.

PubMed

Cerenius, Lage; Liu, Haipeng; Zhang, Yanjiao; Rimphanitchayakit, Vichien; Tassanakajon, Anchalee; Gunnar Andersson, M; Söderhäll, Kenneth; Söderhäll, Irene

2010-01-01

Crustacean hemocytes were found to produce a large number of transcripts coding for Kazal-type proteinase inhibitors (KPIs). A detailed study performed with the crayfish Pacifastacus leniusculus and the shrimp Penaeus monodon revealed the presence of at least 26 and 20 different Kazal domains from the hemocyte KPIs, respectively. Comparisons with KPIs from other taxa indicate that the sequences of these domains evolve rapidly. A few conserved positions, e.g. six invariant cysteines were present in all domain sequences whereas the position of P1 amino acid, a determinant for substrate specificity, varied highly. A study with a single crayfish animal suggested that even at the individual level considerable sequence variability among hemocyte KPIs produced exist. Expression analysis of four crayfish KPI transcripts in hematopoietic tissue cells and different hemocyte types suggest that some of these KPIs are likely to be involved in hematopoiesis or hemocyte release as they were produced in particular hemocyte types or maturation stages only.

Is frictional heating needed to cause dramatic weakening of nanoparticle gouge during seismic slip? Insights from friction experiments with variable thermal evolutions

NASA Astrophysics Data System (ADS)

Yao, Lu; Ma, Shengli; Niemeijer, André R.; Shimamoto, Toshihiko; Platt, John D.

2016-07-01

To examine whether faults can be lubricated by preexisting and newly formed nanoparticles, we perform high-velocity friction experiments on periclase (MgO) nanoparticles and on bare surfaces of Carrara marble cylinders/slices, respectively. Variable temperature conditions were simulated by using host blocks of different thermal conductivities. When temperature rises are relatively low, we observe high friction in nano-MgO tests and unexpected slip strengthening following initial weakening in marble slice tests, suggesting that the dominant weakening mechanisms are of thermal origin. Solely the rolling of nanoparticles without significant temperature rise is insufficient to cause dynamic fault weakening. For nano-MgO experiments, comprehensive investigations suggest that flash heating is the most likely weakening mechanism. In marble experiments, flash heating controls the unique evolutions of friction, and the competition between bulk temperature rise and wear-induced changes of asperity contact numbers seems to strongly affect the efficiency of flash heating.

Variable ecological conditions promote male helping by changing banded mongoose group composition.

PubMed

Marshall, Harry H; Sanderson, Jennifer L; Mwanghuya, Francis; Businge, Robert; Kyabulima, Solomon; Hares, Michelle C; Inzani, Emma; Kalema-Zikusoka, Gladys; Mwesige, Kenneth; Thompson, Faye J; Vitikainen, Emma I K; Cant, Michael A

2016-01-01

Ecological conditions are expected to have an important influence on individuals' investment in cooperative care. However, the nature of their effects is unclear: both favorable and unfavorable conditions have been found to promote helping behavior. Recent studies provide a possible explanation for these conflicting results by suggesting that increased ecological variability, rather than changes in mean conditions, promote cooperative care. However, no study has tested whether increased ecological variability promotes individual-level helping behavior or the mechanisms involved. We test this hypothesis in a long-term study population of the cooperatively breeding banded mongoose, Mungos mungo , using 14 years of behavioral and meteorological data to explore how the mean and variability of ecological conditions influence individual behavior, body condition, and survival. Female body condition was more sensitive to changes in rainfall leading to poorer female survival and pronounced male-biased group compositions after periods of high rainfall variability. After such periods, older males invested more in helping behavior, potentially because they had fewer mating opportunities. These results provide the first empirical evidence for increased individual helping effort in more variable ecological conditions and suggest this arises because of individual differences in the effect of ecological conditions on body condition and survival, and the knock-on effect on social group composition. Individual differences in sensitivity to environmental variability, and the impacts this has on the internal structure and composition of animal groups, can exert a strong influence on the evolution and maintenance of social behaviors, such as cooperative care.

Variable ecological conditions promote male helping by changing banded mongoose group composition

PubMed Central

Sanderson, Jennifer L.; Mwanghuya, Francis; Businge, Robert; Kyabulima, Solomon; Hares, Michelle C.; Inzani, Emma; Kalema-Zikusoka, Gladys; Mwesige, Kenneth; Thompson, Faye J.; Vitikainen, Emma I. K.; Cant, Michael A.

2016-01-01

Ecological conditions are expected to have an important influence on individuals’ investment in cooperative care. However, the nature of their effects is unclear: both favorable and unfavorable conditions have been found to promote helping behavior. Recent studies provide a possible explanation for these conflicting results by suggesting that increased ecological variability, rather than changes in mean conditions, promote cooperative care. However, no study has tested whether increased ecological variability promotes individual-level helping behavior or the mechanisms involved. We test this hypothesis in a long-term study population of the cooperatively breeding banded mongoose, Mungos mungo, using 14 years of behavioral and meteorological data to explore how the mean and variability of ecological conditions influence individual behavior, body condition, and survival. Female body condition was more sensitive to changes in rainfall leading to poorer female survival and pronounced male-biased group compositions after periods of high rainfall variability. After such periods, older males invested more in helping behavior, potentially because they had fewer mating opportunities. These results provide the first empirical evidence for increased individual helping effort in more variable ecological conditions and suggest this arises because of individual differences in the effect of ecological conditions on body condition and survival, and the knock-on effect on social group composition. Individual differences in sensitivity to environmental variability, and the impacts this has on the internal structure and composition of animal groups, can exert a strong influence on the evolution and maintenance of social behaviors, such as cooperative care. PMID:27418750

How temperament and personality contribute to the maladjustment of children with autism.

PubMed

De Pauw, Sarah S W; Mervielde, Ivan; Van Leeuwen, Karla G; De Clercq, Barbara J

2011-02-01

To test the spectrum hypothesis--postulating that clinical and non-clinical samples are primarily differentiated by mean-level differences--, this study evaluates differences in parent-rated temperament, personality and maladjustment among a low-symptom (N = 81), a high-symptom (N = 94) ASD-group, and a comparison group (N = 500). These classic spectrum hypothesis tests are extended by adding tests for similarity in variances, reliabilities and patterns of covariation between relevant variables. Children with ASD exhibit more extreme means, except for dominance. The low- and high-symptom ASD-groups are primarily differentiated by mean sociability and internal distress. Striking similarities in reliability and pattern of covariation of variables suggest that comparable processes link traits to maladaptation in low- and high-symptom children with ASD and in children with and without autism.

The impact of glycaemic variability on wound healing in the diabetic foot - A retrospective study of new ulcers presenting to a specialist multidisciplinary foot clinic.

PubMed

Dhatariya, Ketan K; Li Ping Wah-Pun Sin, Edwin; Cheng, Joyce Oi Suet; Li, Francesca Yan Nok; Yue, Anson Wei Yue; Gooday, Catherine; Nunney, Ian

2018-01-01

Glycaemic variability - the visit-to-visit variation in HbA1c - plays a possible role in the development of micro and macrovascular disease in patients with diabetes. Whether HbA1c variability is a factor determining wound healing in diabetic foot ulcers remains unknown. We aimed to determine whether HbA1c variability is associated with foot ulcer healing time. A retrospective analysis of patients presenting to our specialist multidisciplinary foot clinic between July 2013 and March 2015, with at least three HbA1c measurements within five years of presentation and more than two follow-up reviews. HbA1c variation was measured by magnitude of standard deviation. 629 new referrals were seen between July 2013 and March 2015. Of these, 172 patients had their number of days to healing recorded and sufficient numbers of HbA1c values to determine variability. The overall geometric mean days to heal was 91.1 days (SD 80.8-102.7). In the low HbA1c variability group the geometric mean days to heal was 78.0 days (60.2-101.2) vs 126.9 days (102.0-158.0) in the high Hb1Ac variability group (p = .032). Those with low HbA1c (<58 mmol/mol) and low variability healed faster than those with high HbA1c and high variability (73.5 days [59.5-90.8] vs 111.0 days [92.0-134.0], p = .007). Additionally, our results show that time to healing is more dependent on the mean HbA1c than the variability in HbA1c (p = .007). Our data suggest that there was a significant association between HbA1c variability and healing time in diabetic foot ulcers. Copyright © 2017 Elsevier B.V. All rights reserved.

The Use of Scale-Dependent Precision to Increase Forecast Accuracy in Earth System Modelling

NASA Astrophysics Data System (ADS)

Thornes, Tobias; Duben, Peter; Palmer, Tim

2016-04-01

At the current pace of development, it may be decades before the 'exa-scale' computers needed to resolve individual convective clouds in weather and climate models become available to forecasters, and such machines will incur very high power demands. But the resolution could be improved today by switching to more efficient, 'inexact' hardware with which variables can be represented in 'reduced precision'. Currently, all numbers in our models are represented as double-precision floating points - each requiring 64 bits of memory - to minimise rounding errors, regardless of spatial scale. Yet observational and modelling constraints mean that values of atmospheric variables are inevitably known less precisely on smaller scales, suggesting that this may be a waste of computer resources. More accurate forecasts might therefore be obtained by taking a scale-selective approach whereby the precision of variables is gradually decreased at smaller spatial scales to optimise the overall efficiency of the model. To study the effect of reducing precision to different levels on multiple spatial scales, we here introduce a new model atmosphere developed by extending the Lorenz '96 idealised system to encompass three tiers of variables - which represent large-, medium- and small-scale features - for the first time. In this chaotic but computationally tractable system, the 'true' state can be defined by explicitly resolving all three tiers. The abilities of low resolution (single-tier) double-precision models and similar-cost high resolution (two-tier) models in mixed-precision to produce accurate forecasts of this 'truth' are compared. The high resolution models outperform the low resolution ones even when small-scale variables are resolved in half-precision (16 bits). This suggests that using scale-dependent levels of precision in more complicated real-world Earth System models could allow forecasts to be made at higher resolution and with improved accuracy. If adopted, this new paradigm would represent a revolution in numerical modelling that could be of great benefit to the world.

Evaluating climatic response to external radiative forcing during the late Miocene to early Pliocene: New perspectives from eastern equatorial Pacific (IODP U1338) and North Atlantic (ODP 982) locations

NASA Astrophysics Data System (ADS)

Drury, Anna Joy; John, Cédric M.; Shevenell, Amelia E.

2016-01-01

Orbital-scale climate variability during the latest Miocene-early Pliocene is poorly understood due to a lack of high-resolution records spanning 8.0-3.5 Ma, which resolve all orbital cycles. Assessing this variability improves understanding of how Earth's system sensitivity to insolation evolves and provides insight into the factors driving the Messinian Salinity Crisis (MSC) and the Late Miocene Carbon Isotope Shift (LMCIS). New high-resolution benthic foraminiferal Cibicidoides mundulus δ18O and δ13C records from equatorial Pacific International Ocean Drilling Program Site U1338 are correlated to North Atlantic Ocean Drilling Program Site 982 to obtain a global perspective. Four long-term benthic δ18O variations are identified: the Tortonian-Messinian, Miocene-Pliocene, and Early-Pliocene Oxygen Isotope Lows (8-7, 5.9-4.9, and 4.8-3.5 Ma) and the Messinian Oxygen Isotope High (MOH; 7-5.9 Ma). Obliquity-paced variability dominates throughout, except during the MOH. Eleven new orbital-scale isotopic stages are identified between 7.4 and 7.1 Ma. Cryosphere and carbon cycle sensitivities, estimated from δ18O and δ13C variability, suggest a weak cryosphere-carbon cycle coupling. The MSC termination coincided with moderate cryosphere sensitivity and reduced global ice sheets. The LMCIS coincided with reduced carbon cycle sensitivity, suggesting a driving force independent of insolation changes. The response of the cryosphere and carbon cycle to obliquity forcing is established, defined as Earth System Response (ESR). Observations reveal that two late Miocene-early Pliocene climate states existed. The first is a prevailing dynamic state with moderate ESR and obliquity-driven Antarctic ice variations, associated with reduced global ice volumes. The second is a stable state, which occurred during the MOH, with reduced ESR and lower obliquity-driven variability, associated with expanded global ice volumes.

Eddy-driven low-frequency variability: physics and observability through altimetry

NASA Astrophysics Data System (ADS)

Penduff, Thierry; Sérazin, Guillaume; Arbic, Brian; Mueller, Malte; Richman, James G.; Shriver, Jay F.; Morten, Andrew J.; Scott, Robert B.

2015-04-01

Model studies have revealed the propensity of the eddying ocean circulation to generate strong low-frequency variability (LFV) intrinsically, i.e. without low-frequency atmospheric variability. In the present study, gridded satellite altimeter products, idealized quasi-geostrophic (QG) turbulent simulations, and realistic high-resolution global ocean simulations are used to study the spontaneous tendency of mesoscale (relatively high frequency and high wavenumber) kinetic energy to non-linearly cascade towards larger time and space scales. The QG model reveals that large-scale variability, arising from the well-known spatial inverse cascade, is associated with low frequencies. Low-frequency, low-wavenumber energy is maintained primarily by nonlinearities in the QG model, with forcing (by large-scale shear) and friction playing secondary roles. In realistic simulations, nonlinearities also generally drive kinetic energy to low frequencies and low wavenumbers. In some, but not all, regions of the gridded altimeter product, surface kinetic energy is also found to cascade toward low frequencies. Exercises conducted with the realistic model suggest that the spatial and temporal filtering inherent in the construction of gridded satellite altimeter maps may contribute to the discrepancies seen in some regions between the direction of frequency cascade in models versus gridded altimeter maps. Finally, the range of frequencies that are highly energized and engaged these cascades appears much greater than the range of highly energized and engaged wavenumbers. Global eddying simulations, performed in the context of the CHAOCEAN project in collaboration with the CAREER project, provide estimates of the range of timescales that these oceanic nonlinearities are likely to feed without external variability.

Variations on an Expectancy-Value Model of Motivation in Science.

PubMed

DeBacker; Nelson

1999-04-01

Relationships among motivational variables from goal theory and expectancy-value theory were investigated in this correlational study of high school students. Self-report surveys of motivation in science were collected during biology classes from 69 males and 80 females. Outcome measures were effort, persistence, and achievement. Gender differences were noted in the pattern of zero-order correlations. Internal motivation variables were related to achievement in males but not females. Regression analyses indicated that the motivation variables explained large proportions of variance in the outcomes. However, the contribution of individual variables differed by gender. Most notable was perceived ability, which contributed significantly to predicting outcome measures for females but not males. Findings suggest that interventions may need to focus on different motivational aspects depending on gender. Copyright 1999 Academic Press.

Modeling photovoltaic diffusion: an analysis of geospatial datasets

NASA Astrophysics Data System (ADS)

Davidson, Carolyn; Drury, Easan; Lopez, Anthony; Elmore, Ryan; Margolis, Robert

2014-07-01

This study combines address-level residential photovoltaic (PV) adoption trends in California with several types of geospatial information—population demographics, housing characteristics, foreclosure rates, solar irradiance, vehicle ownership preferences, and others—to identify which subsets of geospatial information are the best predictors of historical PV adoption. Number of rooms, heating source and house age were key variables that had not been previously explored in the literature, but are consistent with the expected profile of a PV adopter. The strong relationship provided by foreclosure indicators and mortgage status have less of an intuitive connection to PV adoption, but may be highly correlated with characteristics inherent in PV adopters. Next, we explore how these predictive factors and model performance varies between different Investor Owned Utility (IOU) regions in California, and at different spatial scales. Results suggest that models trained with small subsets of geospatial information (five to eight variables) may provide similar explanatory power as models using hundreds of geospatial variables. Further, the predictive performance of models generally decreases at higher resolution, i.e., below ZIP code level since several geospatial variables with coarse native resolution become less useful for representing high resolution variations in PV adoption trends. However, for California we find that model performance improves if parameters are trained at the regional IOU level rather than the state-wide level. We also find that models trained within one IOU region are generally representative for other IOU regions in CA, suggesting that a model trained with data from one state may be applicable in another state.

Bud development and hydraulics

PubMed Central

Cochard, Hervé

2008-01-01

The distal zone of one-year-old apple (Malus domestica) shoots was studied on five cultivars for bud size and composition (number of appendages) and hydraulic conductance before bud burst. Our hypothesis was that bud development was related to hydraulic conductance of the sap pathway to the bud independent of an acrotonic (proximal vs. distal) effect. Bud size and composition, and hydraulic conductance, were highly variable for all cultivars. A positive correlation was demonstrated between both the number of cataphylls and green-leaf primordia and hydraulic conductance. Cultivar and bud size affected the intercept of these relationships more than the slope suggesting similar scaling between these variables but different hydraulic efficiencies. A great proportion of small buds were also characterized by null values of hydraulic conductance. Our study suggests that hydraulically mediated competitions exist between adjacent buds within a same branching zone prefiguring the variability of lateral types in the following growing season. It is hypothesized that this developmental patterning is driven by hydraulic characteristics of the whole-metamer, including the subtending leaf, during bud development. PMID:19704779

Cortical Action Potential Backpropagation Explains Spike Threshold Variability and Rapid-Onset Kinetics

PubMed Central

Yu, Yuguo; Shu, Yousheng; McCormick, David A.

2008-01-01

Neocortical action potential responses in vivo are characterized by considerable threshold variability, and thus timing and rate variability, even under seemingly identical conditions. This finding suggests that cortical ensembles are required for accurate sensorimotor integration and processing. Intracellularly, trial-to-trial variability results not only from variation in synaptic activities, but also in the transformation of these into patterns of action potentials. Through simultaneous axonal and somatic recordings and computational simulations, we demonstrate that the initiation of action potentials in the axon initial segment followed by backpropagation of these spikes throughout the neuron results in a distortion of the relationship between the timing of synaptic and action potential events. In addition, this backpropagation also results in an unusually high rate of rise of membrane potential at the foot of the action potential. The distortion of the relationship between the amplitude time course of synaptic inputs and action potential output caused by spike back-propagation results in the appearance of high spike threshold variability at the level of the soma. At the point of spike initiation, the axon initial segment, threshold variability is considerably less. Our results indicate that spike generation in cortical neurons is largely as expected by Hodgkin—Huxley theory and is more precise than previously thought. PMID:18632930

Impact of glycemic variability on the occurrence of periprocedural myocardial infarction and major adverse cardiovascular events (MACE) after coronary intervention in patients with stable angina pectoris at 6months follow-up.

PubMed

Xia, Jinggang; Xu, Ji; Hu, Shaodong; Hao, Hengjian; Yin, Chunlin; Xu, Dong

2017-08-01

We explored the impact of glycemic variability on the occurrence of periprocedural myocardial infarction and major adverse cardiovascular events (MACE) after coronary intervention in patients with stable angina pectoris (SAP) at 6months follow-up. From May 2015 to April 2016, a total of 746 patients with SAP were divided to high glycemic variability group (H group) (n=261) and low glycemic variability group (L group) (n=485). The primary end point was incidence of periprocedural myocardial infarction and MACE at 6months follow-up. The occurrence of periprocedural myocardial infarction occurred in 18.8% of patients in H group and in 12.4% in L group (P=0.03). The incidence of MACE at 6months follow-up was 9.6% in H group and 4.5% in L group (P=0.01). Multivariable analysis suggested that high glycemic variability conferred a 53% risk increment of 6months follow-up MACE (odds ratio 2.13, 95% confidence interval 1.85-5.38; P=0.01). The trial shows that higher blood glucose variability was correlated with higher incidence of periprocedural myocardial infarction and MACE at 6months follow-up. Copyright © 2017. Published by Elsevier B.V.

Characterizing local variability in long‐period horizontal tilt noise

USGS Publications Warehouse

Rohde, M.D.; Ringler, Adam; Hutt, Charles R.; Wilson, David; Holland, Austin; Sandoval, L.D; Storm, Tyler

2017-01-01

Horizontal seismic data are dominated by atmospherically induced tilt noise at long periods (i.e., 30 s and greater). Tilt noise limits our ability to use horizontal data for sensitive seismological studies such as observing free earth modes. To better understand the local spatial variability of long‐period horizontal noise, we observe horizontal noise during quiet time periods in the Albuquerque Seismological Laboratory (ASL) underground vault using four small‐aperture array configurations. Each array comprises eight Streckeisen STS‐2 broadband seismometers. We analyze the spectral content of the data using power spectral density and magnitude‐squared coherence (γ2‐coherence). Our results show a high degree of spatial variability and frequency dependence in the long‐period horizontal wavefield. The variable nature of long‐period horizontal noise in the ASL vault suggests that it might be highly local in nature and not easily characterized by simple physical models when overall noise levels are low, making it difficult to identify locations in the vault with lower horizontal noise. This variability could be limiting our ability to apply coherence analysis for estimating horizontal sensor self‐noise and could also complicate various indirect methods for removing long‐period horizontal noise (e.g., collocated rotational sensor or microbarograph).

A Satellite-Based Imaging Instrumentation Concept for Hyperspectral Thermal Remote Sensing.

PubMed

Udelhoven, Thomas; Schlerf, Martin; Segl, Karl; Mallick, Kaniska; Bossung, Christian; Retzlaff, Rebecca; Rock, Gilles; Fischer, Peter; Müller, Andreas; Storch, Tobias; Eisele, Andreas; Weise, Dennis; Hupfer, Werner; Knigge, Thiemo

2017-07-01

This paper describes the concept of the hyperspectral Earth-observing thermal infrared (TIR) satellite mission HiTeSEM (High-resolution Temperature and Spectral Emissivity Mapping). The scientific goal is to measure specific key variables from the biosphere, hydrosphere, pedosphere, and geosphere related to two global problems of significant societal relevance: food security and human health. The key variables comprise land and sea surface radiation temperature and emissivity, surface moisture, thermal inertia, evapotranspiration, soil minerals and grain size components, soil organic carbon, plant physiological variables, and heat fluxes. The retrieval of this information requires a TIR imaging system with adequate spatial and spectral resolutions and with day-night following observation capability. Another challenge is the monitoring of temporally high dynamic features like energy fluxes, which require adequate revisit time. The suggested solution is a sensor pointing concept to allow high revisit times for selected target regions (1-5 days at off-nadir). At the same time, global observations in the nadir direction are guaranteed with a lower temporal repeat cycle (>1 month). To account for the demand of a high spatial resolution for complex targets, it is suggested to combine in one optic (1) a hyperspectral TIR system with ~75 bands at 7.2-12.5 µm (instrument NEDT 0.05 K-0.1 K) and a ground sampling distance (GSD) of 60 m, and (2) a panchromatic high-resolution TIR-imager with two channels (8.0-10.25 µm and 10.25-12.5 µm) and a GSD of 20 m. The identified science case requires a good correlation of the instrument orbit with Sentinel-2 (maximum delay of 1-3 days) to combine data from the visible and near infrared (VNIR), the shortwave infrared (SWIR) and TIR spectral regions and to refine parameter retrieval.

Modeling the temporal variability of zinc concentrations in zinc roof runoff-experimental study and uncertainty analysis.

PubMed

Sage, Jérémie; El Oreibi, Elissar; Saad, Mohamed; Gromaire, Marie-Christine

2016-08-01

This study investigates the temporal variability of zinc concentrations from zinc roof runoff. The influence of rainfall characteristics and dry period duration is evaluated by combining laboratory experiment on small zinc sheets and in situ measurements under real weather conditions from a 1.6-m(2) zinc panel. A reformulation of a commonly used conceptual runoff quality model is introduced and its ability to simulate the evolution of zinc concentrations is evaluated. A systematic and sharp decrease from initially high to relatively low and stable zinc concentrations after 0.5 to 2 mm of rainfall is observed for both experiments, suggesting that highly soluble corrosion products are removed at early stages of runoff. A moderate dependence between antecedent dry period duration and the magnitude of zinc concentrations at the beginning of a rain event is evidenced. Contrariwise, results indicate that concentrations are not significantly influenced by rainfall intensities. Simulated rainfall experiment nonetheless suggests that a slight effect of rainfall intensities may be expected after the initial decrease of concentrations. Finally, this study shows that relatively simple conceptual runoff quality models may be adopted to simulate the variability of zinc concentrations during a rain event and from a rain event to another.

Comparing mechanistic and empirical approaches to modeling the thermal niche of almond

NASA Astrophysics Data System (ADS)

Parker, Lauren E.; Abatzoglou, John T.

2017-09-01

Delineating locations that are thermally viable for cultivating high-value crops can help to guide land use planning, agronomics, and water management. Three modeling approaches were used to identify the potential distribution and key thermal constraints on on almond cultivation across the southwestern United States (US), including two empirical species distribution models (SDMs)—one using commonly used bioclimatic variables (traditional SDM) and the other using more physiologically relevant climate variables (nontraditional SDM)—and a mechanistic model (MM) developed using published thermal limitations from field studies. While models showed comparable results over the majority of the domain, including over existing croplands with high almond density, the MM suggested the greatest potential for the geographic expansion of almond cultivation, with frost susceptibility and insufficient heat accumulation being the primary thermal constraints in the southwestern US. The traditional SDM over-predicted almond suitability in locations shown by the MM to be limited by frost, whereas the nontraditional SDM showed greater agreement with the MM in these locations, indicating that incorporating physiologically relevant variables in SDMs can improve predictions. Finally, opportunities for geographic expansion of almond cultivation under current climatic conditions in the region may be limited, suggesting that increasing production may rely on agronomical advances and densifying current almond plantations in existing locations.

Suicidality in Bipolar I Disorder

ERIC Educational Resources Information Center

Johnson, Sheri L.; McMurrich, Stephanie L.; Yates, Marisa

2005-01-01

People with bipolar disorder are at high suicide risk. The literature suggests that suicidality is predicted by higher symptom severity and less use of pharmacological agents, but few studies have examined the joint contributions of these variables. The present study examines the conjoint contribution of symptom severity and pharmacological…

Task conflict and proactive control: A computational theory of the Stroop task.

PubMed

Kalanthroff, Eyal; Davelaar, Eddy J; Henik, Avishai; Goldfarb, Liat; Usher, Marius

2018-01-01

The Stroop task is a central experimental paradigm used to probe cognitive control by measuring the ability of participants to selectively attend to task-relevant information and inhibit automatic task-irrelevant responses. Research has revealed variability in both experimental manipulations and individual differences. Here, we focus on a particular source of Stroop variability, the reverse-facilitation (RF; faster responses to nonword neutral stimuli than to congruent stimuli), which has recently been suggested as a signature of task conflict. We first review the literature that shows RF variability in the Stroop task, both with regard to experimental manipulations and to individual differences. We suggest that task conflict variability can be understood as resulting from the degree of proactive control that subjects recruit in advance of the Stroop stimulus. When the proactive control is high, task conflict does not arise (or is resolved very quickly), resulting in regular Stroop facilitation. When proactive control is low, task conflict emerges, leading to a slow-down in congruent and incongruent (but not in neutral) trials and thus to Stroop RF. To support this suggestion, we present a computational model of the Stroop task, which includes the resolution of task conflict and its modulation by proactive control. Results show that our model (a) accounts for the variability in Stroop-RF reported in the experimental literature, and (b) solves a challenge to previous Stroop models-their ability to account for reaction time distributional properties. Finally, we discuss theoretical implications to Stroop measures and control deficits observed in some psychopathologies. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

High-velocity winds from a dwarf nova during outburst

NASA Technical Reports Server (NTRS)

Cordova, F. A.; Mason, K. O.

1982-01-01

An ultraviolet spectrum of the dwarf nova TW Vir during an optical outburst shows shortward-shifted absorption features with edge velocities as high as 4800 km/s, about the escape velocity of a white dwarf. A comparison of this spectrum with the UV spectra of other cataclysmic variables suggests that mass loss is evident only for systems with relatively high luminosities (more than about 10 solar luminosities) and low inclination angles with respect to the observer's line of sight. The mass loss rate for cataclysmic variables is of order 10 to the -11th solar mass per yr; this is from 0.01 to 0.001 of the mass accretion rate onto the compact star in the binary. The mass loss may occur by a mechanism similar to that invoked for early-type stars, i.e., radiation absorbed in the lines accelerates the accreting gas to the high velocities observed.

Improving preparedness of farmers to Climate Variability: A case study of Vidarbha region of Maharashtra, India

NASA Astrophysics Data System (ADS)

Swami, D.; Parthasarathy, D.; Dave, P.

2016-12-01

A key objective of the ongoing research is to understand the risk and vulnerability of agriculture and farming communities with respect to multiple climate change attributes, particularly monsoon variability and hydrology such as ground water availability. Climate Variability has always been a feature affecting Indian agriculture but the nature and characteristics of this variability is not well understood. Indian monsoon patterns are highly variable and most of the studies focus on larger domain such as Central India or Western coast (Ghosh et al., 2009) but district level analysis is missing i.e. the linkage between agriculture and climate variables at finer scale has not been investigated comprehensively. For example, Eastern Vidarbha region in Maharashtra is considered as one of the most agriculturally sensitive region in India, where every year a large number of farmers commit suicide. The main reasons for large number of suicides are climate related stressors such as droughts, hail storms, and monsoon variability aggravated with poor socio-economic conditions. Present study has tried to explore the areas in Vidarbha region of Maharashtra where famers and crop productivity, specifically cotton, sorghum, is highly vulnerable to monsoon variability, hydrological and socio-economic variables which are further modelled to determine the maximal contributing factor towards crops and farmers' vulnerability. After analysis using primary and secondary data, it will aid in decision making regarding field operations such as time of sowing, harvesting and irrigation requirements by optimizing the cropping pattern with climatic, hydrological and socio-economic variables. It also suggests the adaptation strategies to farmers regarding different types of cropping and water harvesting practices, optimized dates and timings for harvesting, sowing, water and nutrient requirements of particular crops according to the specific region. Primarily along with secondary analysis captured here can be highly beneficial for the farmers and policy makers while formulating agricultural policies related to climate change.

Spatial Variability of Geriatric Depression Risk in a High-Density City: A Data-Driven Socio-Environmental Vulnerability Mapping Approach.

PubMed

Ho, Hung Chak; Lau, Kevin Ka-Lun; Yu, Ruby; Wang, Dan; Woo, Jean; Kwok, Timothy Chi Yui; Ng, Edward

2017-08-31

Previous studies found a relationship between geriatric depression and social deprivation. However, most studies did not include environmental factors in the statistical models, introducing a bias to estimate geriatric depression risk because the urban environment was found to have significant associations with mental health. We developed a cross-sectional study with a binomial logistic regression to examine the geriatric depression risk of a high-density city based on five social vulnerability factors and four environmental measures. We constructed a socio-environmental vulnerability index by including the significant variables to map the geriatric depression risk in Hong Kong, a high-density city characterized by compact urban environment and high-rise buildings. Crude and adjusted odds ratios (ORs) of the variables were significantly different, indicating that both social and environmental variables should be included as confounding factors. For the comprehensive model controlled by all confounding factors, older adults who were of lower education had the highest geriatric depression risks (OR: 1.60 (1.21, 2.12)). Higher percentage of residential area and greater variation in building height within the neighborhood also contributed to geriatric depression risk in Hong Kong, while average building height had negative association with geriatric depression risk. In addition, the socio-environmental vulnerability index showed that higher scores were associated with higher geriatric depression risk at neighborhood scale. The results of mapping and cross-section model suggested that geriatric depression risk was associated with a compact living environment with low socio-economic conditions in historical urban areas in Hong Kong. In conclusion, our study found a significant difference in geriatric depression risk between unadjusted and adjusted models, suggesting the importance of including environmental factors in estimating geriatric depression risk. We also developed a framework to map geriatric depression risk across a city, which can be used for identifying neighborhoods with higher risk for public health surveillance and sustainable urban planning.

Spatial Variability of Geriatric Depression Risk in a High-Density City: A Data-Driven Socio-Environmental Vulnerability Mapping Approach

PubMed Central

Lau, Kevin Ka-Lun; Yu, Ruby; Wang, Dan; Kwok, Timothy Chi Yui; Ng, Edward

2017-01-01

Previous studies found a relationship between geriatric depression and social deprivation. However, most studies did not include environmental factors in the statistical models, introducing a bias to estimate geriatric depression risk because the urban environment was found to have significant associations with mental health. We developed a cross-sectional study with a binomial logistic regression to examine the geriatric depression risk of a high-density city based on five social vulnerability factors and four environmental measures. We constructed a socio-environmental vulnerability index by including the significant variables to map the geriatric depression risk in Hong Kong, a high-density city characterized by compact urban environment and high-rise buildings. Crude and adjusted odds ratios (ORs) of the variables were significantly different, indicating that both social and environmental variables should be included as confounding factors. For the comprehensive model controlled by all confounding factors, older adults who were of lower education had the highest geriatric depression risks (OR: 1.60 (1.21, 2.12)). Higher percentage of residential area and greater variation in building height within the neighborhood also contributed to geriatric depression risk in Hong Kong, while average building height had negative association with geriatric depression risk. In addition, the socio-environmental vulnerability index showed that higher scores were associated with higher geriatric depression risk at neighborhood scale. The results of mapping and cross-section model suggested that geriatric depression risk was associated with a compact living environment with low socio-economic conditions in historical urban areas in Hong Kong. In conclusion, our study found a significant difference in geriatric depression risk between unadjusted and adjusted models, suggesting the importance of including environmental factors in estimating geriatric depression risk. We also developed a framework to map geriatric depression risk across a city, which can be used for identifying neighborhoods with higher risk for public health surveillance and sustainable urban planning. PMID:28858265

Subjective Socioeconomic Status Moderates the Association between Discrimination and Depression in African American Youth.

PubMed

Assari, Shervin; Preiser, Brianna; Lankarani, Maryam Moghani; Caldwell, Cleopatra H

2018-04-20

Background: Most of the literature on the association between socioeconomic status (SES) and health is focused on the protective effects of SES. However, a growing literature suggests that high SES may also operate as a vulnerability factor. Aims: Using a national sample of African American youth, this study compared the effects of perceived discrimination on major depressive disorder (MDD) based on SES. Methods: The current cross-sectional study included 810 African American youth who participated in the National Survey of American Life-Adolescent supplement. The independent variable was perceived discrimination. Lifetime, 12-month, and 30-day MDD were the dependent variables. Age and gender were covariates. Three SES indicators (subjective SES, income, and poverty index) were moderators. We used logistic regressions for data analysis. Results: Perceived discrimination was associated with higher risk of lifetime, 12-month, and 30-day MDD. Interactions were found between subjective SES and perceived discrimination on lifetime, 12-month, and 30-day MDD, suggesting a stronger effect of perceived discrimination in youth with high subjective SES. Objective measures of SES (income and poverty index) did not interact with perceived discrimination on MDD. Conclusion: While perceived discrimination is a universally harmful risk factor for MDD, its effect may depend on the SES of the individual. Findings suggest that high subjective SES may operate as a vulnerability factor for African American youth.

An evaluation of the effect of recent temperature variability on the prediction of coral bleaching events.

PubMed

Donner, Simon D

2011-07-01

Over the past 30 years, warm thermal disturbances have become commonplace on coral reefs worldwide. These periods of anomalous sea surface temperature (SST) can lead to coral bleaching, a breakdown of the symbiosis between the host coral and symbiotic dinoflagellates which reside in coral tissue. The onset of bleaching is typically predicted to occur when the SST exceeds a local climatological maximum by 1 degrees C for a month or more. However, recent evidence suggests that the threshold at which bleaching occurs may depend on thermal history. This study uses global SST data sets (HadISST and NOAA AVHRR) and mass coral bleaching reports (from Reefbase) to examine the effect of historical SST variability on the accuracy of bleaching prediction. Two variability-based bleaching prediction methods are developed from global analysis of seasonal and interannual SST variability. The first method employs a local bleaching threshold derived from the historical variability in maximum annual SST to account for spatial variability in past thermal disturbance frequency. The second method uses a different formula to estimate the local climatological maximum to account for the low seasonality of SST in the tropics. The new prediction methods are tested against the common globally fixed threshold method using the observed bleaching reports. The results find that estimating the bleaching threshold from local historical SST variability delivers the highest predictive power, but also a higher rate of Type I errors. The second method has the lowest predictive power globally, though regional analysis suggests that it may be applicable in equatorial regions. The historical data analysis suggests that the bleaching threshold may have appeared to be constant globally because the magnitude of interannual variability in maximum SST is similar for many of the world's coral reef ecosystems. For example, the results show that a SST anomaly of 1 degrees C is equivalent to 1.73-2.94 standard deviations of the maximum monthly SST for two-thirds of the world's coral reefs. Coral reefs in the few regions that experience anomalously high interannual SST variability like the equatorial Pacific could prove critical to understanding how coral communities acclimate or adapt to frequent and/or severe thermal disturbances.

Genetic Variability and Distribution of Mating Type Alleles in Field Populations of Leptosphaeria maculans from France

PubMed Central

Gout, Lilian; Eckert, Maria; Rouxel, Thierry; Balesdent, Marie-Hélène

2006-01-01

Leptosphaeria maculans is the most ubiquitous fungal pathogen of Brassica crops and causes the devastating stem canker disease of oilseed rape worldwide. We used minisatellite markers to determine the genetic structure of L. maculans in four field populations from France. Isolates were collected at three different spatial scales (leaf, 2-m2 field plot, and field) enabling the evaluation of spatial distribution of the mating type alleles and of genetic variability within and among field populations. Within each field population, no gametic disequilibrium between the minisatellite loci was detected and the mating type alleles were present at equal frequencies. Both sexual and asexual reproduction occur in the field, but the genetic structure of these populations is consistent with annual cycles of randomly mating sexual reproduction. All L. maculans field populations had a high level of gene diversity (H = 0.68 to 0.75) and genotypic diversity. Within each field population, the number of genotypes often was very close to the number of isolates. Analysis of molecular variance indicated that >99.5% of the total genetic variability was distributed at a small spatial scale, i.e., within 2-m2 field plots. Population differentiation among the four field populations was low (GST < 0.02), suggesting a high degree of gene exchange between these populations. The high gene flow evidenced here in French populations of L. maculans suggests a rapid countrywide diffusion of novel virulence alleles whenever novel resistance sources are used. PMID:16391041

The Unusual Binary Pulsar PSR J1744-3922: Radio Flux Variability, Near-Infrared Observation, and Evolution

NASA Astrophysics Data System (ADS)

Breton, R. P.; Roberts, M. S. E.; Ransom, S. M.; Kaspi, V. M.; Durant, M.; Bergeron, P.; Faulkner, A. J.

2007-06-01

PSR J1744-3922 is a binary pulsar exhibiting highly variable pulsed radio emission. We report on a statistical multifrequency study of the pulsed radio flux variability which suggests that this phenomenon is extrinsic to the pulsar and possibly tied to the companion, although not strongly correlated with orbital phase. The pulsar has an unusual combination of characteristics compared to typical recycled pulsars: a long spin period (172 ms); a relatively high magnetic field strength (1.7×1010 G); a very circular, compact orbit of 4.6 hr; and a low-mass companion (0.08 Msolar). These spin and orbital properties are likely inconsistent with standard evolutionary models. We find similarities between the properties of the PSR J1744-3922 system and those of several other known binary pulsar systems, motivating the identification of a new class of binary pulsars. We suggest that this new class could result from: a standard accretion scenario of a magnetar or a high magnetic field pulsar; common envelope evolution with a low-mass star and a neutron star, similar to what is expected for ultracompact X-ray binaries; or accretion induced collapse of a white dwarf. We also report the detection of a possible K'=19.30(15) infrared counterpart at the position of the pulsar, which is relatively bright if the companion is a helium white dwarf at the nominal distance, and discuss its implications for the pulsar's companion and evolutionary history.

Synchronous precipitation reduction in the American Tropics associated with Heinrich 2.

PubMed

Medina-Elizalde, Martín; Burns, Stephen J; Polanco-Martinez, Josué; Lases-Hernández, Fernanda; Bradley, Raymond; Wang, Hao-Cheng; Shen, Chuan-Chou

2017-09-11

During the last ice age temperature in the North Atlantic oscillated in cycles known as Dansgaard-Oeschger (D-O) events. The magnitude of Caribbean hydroclimate change associated with D-O variability and particularly with stadial intervals, remains poorly constrained by paleoclimate records. We present a 3.3 thousand-year long stalagmite δ 18 O record from the Yucatan Peninsula (YP) that spans the interval between 26.5 and 23.2 thousand years before present. We estimate quantitative precipitation variability and the high resolution and dating accuracy of this record allow us to investigate how rainfall in the region responds to D-O events. Quantitative precipitation estimates are based on observed regional amount effect variability, last glacial paleotemperature records, and estimates of the last glacial oxygen isotopic composition of precipitation based on global circulation models (GCMs). The new precipitation record suggests significant low latitude hydrological responses to internal modes of climate variability and supports a role of Caribbean hydroclimate in helping Atlantic Meridional Overturning Circulation recovery during D-O events. Significant in-phase precipitation reduction across the equator in the tropical Americas associated with Heinrich event 2 is suggested by available speleothem oxygen isotope records.

Religious Attendance as Reproductive Support

PubMed Central

Weeden, Jason; Cohen, Adam B.; Kenrick, Douglas T.

2009-01-01

We argue that a central function of religious attendance in the contemporary U.S. is to support a high-fertility, monogamous mating strategy. Although religious attendance is correlated with many demographic, personality, moral, and behavioral variables, we propose that sexual and family variables are at the core of many of these relationships. Numerous researchers have assumed that religious socialization causes people to feel moral reactions and engage in behaviors promoted by religious groups. On our view, mating preferences are centrally involved in individual differences in attraction to religious groups. In a sample of 21,131 individuals who participated in the U.S. General Social Survey, sexual behaviors were the relatively strongest predictors of religious attendance, even after controlling for age and gender. Effects of age and gender on religious attendance were weaker, and substantially reduced when controlling for sexual and family patterns. A sample of 902 college students provided more detailed information on religious, moral, and sexual variables. Results suggest that 1) moral views about sexual behavior are more strongly linked to religious attendance than other moral issues, and 2) mating strategy is more powerful than standard personality variables in predicting religious attendance. These findings suggest that reproductive strategies are at the heart of variations in religious attendance. PMID:21874105

Optimal control of a variable spin speed CMG system for space vehicles. [Control Moment Gyros

NASA Technical Reports Server (NTRS)

Liu, T. C.; Chubb, W. B.; Seltzer, S. M.; Thompson, Z.

1973-01-01

Many future NASA programs require very high accurate pointing stability. These pointing requirements are well beyond anything attempted to date. This paper suggests a control system which has the capability of meeting these requirements. An optimal control law for the suggested system is specified. However, since no direct method of solution is known for this complicated system, a computation technique using successive approximations is used to develop the required solution. The method of calculus of variations is applied for estimating the changes of index of performance as well as those constraints of inequality of state variables and terminal conditions. Thus, an algorithm is obtained by the steepest descent method and/or conjugate gradient method. Numerical examples are given to show the optimal controls.

Seasonal and high-resolution variability in hydrochemistry of the Andes-Amazon

NASA Astrophysics Data System (ADS)

Burt, E.; West, A. J.

2017-12-01

Stream hydrochemistry acts as a record of integrated catchment processes such as the amount of time it takes precipitation to flow through the subsurface and become streamflow (water transit times), water-rock interaction and biogeochemical cycling. Although it is understood that sampling interval affects observed patterns in hydrochemistry, most studies collect samples on a weekly, bi-weekly or monthly schedule due to lack of resources or the difficulty of maintaining automated sampling devices. Here, we attempt to combine information from two sampling time scales, comparing a year-long hydrochemical time series to data from a recent sub-daily sampling campaign. Starting in April 2016, river, soil and rain waters have been collected every two weeks at five small catchments spanning the tropical Andes and Amazon - a natural laboratory for its gradients in topography, erosion rates, precipitation, temperature and flora. Between January and March, 2017, we conducted high frequency sampling for approximately one week at each catchment, sampling at least every four hours including overnight. We will constrain young water fractions (Kirchner, 2016) and storm water fluxes for the experimental catchments using stable isotopes of water as conservative tracers. Major element data will provide the opportunity to make initial constraints on geochemical and hydrologic coupling. Preliminary results suggest that in the Amazon, hydrochemistry patterns are dependent on sampling frequency: the seasonal cycle in stable isotopes of water is highly damped, while the high resolution sampling displays large variability. This suggests that a two-week sampling interval is not frequent enough to capture rapid transport of water, perhaps through preferential flow networks. In the Andes, stable isotopes of water are highly damped in both the seasonal and high resolution cycle, suggesting that the catchment behaves as a "well-mixed" system.

Relations among Executive Function, Number Sense, and Mathematics Achievement in Kindergartners

ERIC Educational Resources Information Center

Irwin, Casey Marie

2013-01-01

Early number sense knowledge is highly predictive of later math achievement (Herbers et al., in press; Jordan, Kaplan, Ramineni, & Locuniak, 2009; Obradovic i et al., 2009). However, research suggests that variables beyond number competencies contribute to students' mathematics achievement, most notably, executive function (Blair & Razza,…

Industrial Landscapes: Perception and Classification as Learning Activities

ERIC Educational Resources Information Center

Peters, Gary; Larkin, Robert P.

1977-01-01

Suggests a high school or college level program of subjective perception and evaluation of industrial landscapes. Slides of local or national industrial sites can be rated and classified as pleasing or unpleasing in terms of variables such as architectural style of building, smokestacks, age, and visible pollution. (AV)

Genetic hitch-hiking extends the range of coast live oak

Treesearch

Richard S. Dodd; Zara Afzal-Rafii; Wasima Mayer

2006-01-01

The northernmost range of coast live oak (Quercus agrifolia) is reported from the Ukiah Valley (Mendocino County, California). Here, field observations suggest that hybridization with interior live oak (Q. wislizeni) is important. Elsewhere in northern California, morphology of coast live oak can be highly variable (particularly...

Risk Profiles of Children Entering Residential Care: A Cluster Analysis

ERIC Educational Resources Information Center

Hagaman, Jessica L.; Trout, Alexandra L.; Chmelka, M. Beth; Thompson, Ronald W.; Reid, Robert

2010-01-01

Children in residential care are a heterogeneous population, presenting various combinations of risks. Existing studies on these children suggest high variability across multiple domains (e.g., academics, behavior). Given this heterogeneity, it is important to begin to identify the combinations and patterns of multiple risks, or risk profiles,…

High sub-seasonal variability in water volume transports, revealed through a new ocean monitoring initiative using autonomous gliders

NASA Astrophysics Data System (ADS)

Heslop, E.; Ruiz, S.; Allen, J.; Tintoré, J.

2012-04-01

One of the clear challenges facing oceanography today is to define variability in ocean processes at a seasonal and sub-seasonal scale, in order to clearly identify the signature of both natural large-scale climatic oscillations and the long-term trends brought about by the human-induced change in atmospheric composition. Without visibility of this variance, which helps to determine the margins of significance for long-term trends and decipher cause and effect, the inferences drawn from sparse data points can be misleading. The cyclonic basin scale circulation pattern in the Western Mediterranean has long been known; the role/contribution that processes in the Balearic Basin play in modifying this is less well defined. The Balearic Channels (channels between the Balearic Islands) are constriction points on this basin scale circulation that appear to exert a controlling influence on the north/south exchange of water masses. Understanding the variability in current flows through these channels is important, not just for the transport of heat and salt, but also for ocean biology that responds to physical variability at the scale of that variability. Earlier studies at a seasonal scale identified; an interannual summer/winter variation of 1 Sv in the strength of the main circulation pattern and a high cruise-to-cruise variability in the pattern and strength of the flows through the channels brought about by mesoscale activity. Initial results using new high-resolution data from glider based monitoring missions across the Ibiza Channel (the main exchange channel in the Balearic Basin), combined with ship and contemporaneous satellite data, indicate surprisingly high and rapid changes in the flows of surface and intermediate waters imposed on the broad seasonal cycle. To date the data suggests that there are three potential 'modes' of water volume transport, generated from the interplay between basin and mesoscale circulation. We will review the concept of transport modes as seen through the earlier seasonal ship based studies and demonstrate that the scales of variability captured by the glider monitoring provides a unique view of variability in this circulation system, which is as high on a weekly timescale as the previously identified seasonal cycle.

Longitudinal Risk and Resilience Factors Predicting Psychiatric Disruption, Mental Health Service Utilization & Military Retention in OIF National Guard Troops

DTIC Science & Technology

2010-04-01

disorders. These predictors were found to be distinct from personality variables (i.e., high negative emotionality and disconstraint) that were...experiencing relationship distress (Meis, Erbes, Polusny, & Compton, 2010). Specifically, high levels of negative emotionality , as measured by the MMPI-2 RF...relationship between negative emotionality (measured at pre-deployment) and relationship maladjustment at post- deployment. This suggests that

Fulgurites: a rock magnetic study of mineralogical changes caused by lightning

NASA Astrophysics Data System (ADS)

Begnini, G. S.; Tohver, E.; Schmieder, M.

2013-05-01

Fulgurites are natural glass samples produced by lightning strikes on rock or soil substrates. Instantaneous electrical discharges of 10-200 kA are typical, and the temperatures produced by lightning strikes exceed 1700C, the melting temperature of quartz. Paleomagnetic observations of lightning strikes typically include high intensity remanent magnetizations with highly-variable to random magnetic directions. Alternating field demagnetization is commonly used to remove the overprinting effects of Lightning Induced Remanent Magnetization (LIRM), indicating low coercivities of the magnetic carriers. We conducted a rock magnetic analysis of 15 specimens of natural fulgurite from South Africa including hysteresis and thermoremanent heating and cooling experiments using a Variable Field Translational Balance. The analysed specimens demonstrate two distinct ranges of Curie temperature: 440-600C and 770-778C, suggesting the presence of both iron oxides (likely Fe-rich magnetite) and a reduced iron alloy, likely kamacite. High temperature, highly reduced assemblages have been reported from petrological observations of fulgurites. Our rock magnetic observations of a metallic iron phase in the fulgurite samples from a terrestrial, surficial environment demonstrates a mineralogical resemblance to differentiated, iron-rich meteorites. We suggest that LIRMs in lightning-struck localities may include a chemical remagnetization associated with lightning-induced electrolysis or reduction of iron oxides.

High food abundance permits the evolution of placentotrophy: evidence from a placental lizard, Pseudemoia entrecasteauxii.

PubMed

Van Dyke, James U; Griffith, Oliver W; Thompson, Michael B

2014-08-01

Mechanisms of reproductive allocation are major determinants of fitness because embryos cannot complete development without receiving sufficient nutrition from their parents. The nourishment of offspring via placentas (placentotrophy) has evolved repeatedly in vertebrates, including multiple times in squamate reptiles (lizards and snakes). Placentotrophy has been suggested to evolve only if food is sufficiently abundant throughout gestation to allow successful embryogenesis. If scarcity of food prevents successful embryogenesis, females should recoup nutrients allocated to embryos via abortion, reabsorption, and/or cannibalism. We tested these hypotheses in the placentotrophic southern grass skink Pseudemoia entrecasteauxii. We fed females one of four diets (high constant, high variable, low constant, and low variable) during gestation and tested the effects of both food amount and schedule of feeding on developmental success, cannibalism rate, placental nutrient transport, offspring size, and maternal growth and body condition. Low food availability reduced developmental success, placental nutrient transport, offspring size, and maternal growth and body condition. Cannibalism of offspring also increased when food was scarce. Schedule of feeding did not affect offspring or mothers. We suggest that high food abundance and ability to abort and cannibalize poor-quality offspring are permissive factors necessary for placentotrophy to be a viable strategy of reproductive allocation.

Glaciation and Hydrologic Variability in Tropical South America During the Last 400,000 Years

NASA Astrophysics Data System (ADS)

Fritz, S. C.; Baker, P. A.; Seltzer, G. O.; Ekdahl, E. J.; Ballantyne, A.

2005-12-01

The expansion and contraction of northern continental ice sheets is a fundamental characteristic of the Quaternary. However, the extent of tropical glaciation is poorly constrained, particularly for periods prior to the Last Glacial Maximum (LGM). Similarly, the magnitude and timing of hydrologic variation in tropical South America is not clearly defined over multiple glacial cycles. Thus, the relative roles of global temperature change and insolation control of the South American Summer Monsoon (SASM) are unclear. We have reconstructed the timing of glaciation and precipitation variability in the tropical Andes of South America from drill cores from Lake Titicaca, Bolivia/Peru. The longest core (site LT01-2B, 235 m water depth) is 136 m and consists of four major silt-dominated units with high magnetic susceptibility, low organic carbon concentration, and no carbonate, which are indicative of extensive glacial activity in the cordillera surrounding the lake. These units alternate with laminated low-susceptibility units, with high carbonate and organic carbon concentrations, which reflect times when detrital input from the watershed was low and lake-level was lowered to below the outlet threshold, driving carbonate precipitation. Thus, the stratigraphy suggests that the core spans four major periods of glaciation and the subsequent interstadials. Core chronology is based on radiocarbon in the uppermost 25m, U-series dates on aragonite laminae, and tuning of the calcium carbonate stratigraphy in the lowermost sediments to the Vostok CO2 record. High-resolution (ca. 100 yr) sampling of sediments spanning the last glacial stage shows distinct millennial-scale variability from 20 - 65 kyr BP. This variability is evident in the periodic deposition of turbidites, which are characterized by low biogenic silica concentrations, elevated benthic diatom abundances, heavy carbon isotopic values, high C/N ratios, and an increase in mean grain size - a composite signal indicative of enhanced input to this deepwater site of material originally deposited in nearshore regions of the lake. U-series ages at the top of the penultimate (pre-Holocene) unit of laminated sediments suggest that the last major low stand of Lake Titicaca dates from MIS 5.5. Diatom data indicate that this was the most saline interval in the recovered sequence and thus suggest that MIS5.5 was the time of maximum aridity. The tuned drill-core magnetic susceptibility record suggests that glacial stages in the tropical Andes were approximately synchronous with high-latitude glacial stages and globally cold climate, with increased glacial activity in the periods 370-322, 300-238, 230-213, 188-139, and 65-15 kyr BP. Overall, the intervals of increased glaciation are periods when Lake Titicaca was deep, fresh, and overflowing, as inferred from calcium carbonate concentration, carbon isotopic values, and the diatom composition. The timing of lake-level change relative to high-latitude climate and insolation variation suggests that the water balance of the tropical Andes was at least as strongly influenced by global temperature change and global-scale boundary conditions as by insolation control of the SASM.

An Eight-Century High-Resolution Paleoclimate Record From the Cariaco Basin: Baseline Variability and the 20th Century

NASA Astrophysics Data System (ADS)

Black, D. E.; Thunell, R. C.; Kaplan, A.; Tappa, E. J.; Peterson, L. C.

2007-12-01

The Cariaco Basin, Venezuela is well-positioned to record a detailed history of surface ocean changes along the southern margin of the Caribbean and the tropical Atlantic. Varved, high deposition rate sediments deposited under anoxic conditions and an abundance of well-preserved microfossils result in one of the few marine records capable of preserving evidence of interannual- to decadal-scale climate variability in the tropical Atlantic. Here we present Mg/Ca and stable oxygen isotope data with sub-decadal resolution derived from sediments deposited over the last 800 years. Mg/Ca measured on the planktic foraminifer Globigerina bulloides from a Cariaco Basin sediment core strongly correlates with spring (March-May) instrumental SSTs between AD 1870 and 1990. The long-term record displays a surprising amount of variability for a tropical location. The temperature swings are not necessarily related to local upwelling variability, but instead represent wider conditions in the Caribbean and western tropical Atlantic. The Mg/Ca-SST record also captures the decadal and multidecadal variability observed in global land and sea surface temperature anomalies, and correlates with Atlantic tropical storm and hurricane frequency over the late-19th and 20th centuries. On average, 20th century temperatures are not the warmest in the entire record, but they do show the largest increase in magnitude and fastest rate of SST change over the last eight hundred years. Stable oxygen isotope data also correlate well with instrumental SSTs, but not over the full instrumental record. Poor correlations with early instrumental SST data suggest a salinity overprint. However, reconstructing δ- water variability using combined Mg/Ca and δ18O data is not straightforward as the δ- water/salinity relationship varies seasonally in the Cariaco Basin. Comparisons with percent titanium data suggest intervals of both local and regional surface salinity changes over the length of the record.

Effects of reaction time variability and age on brain activity during Stroop task performance.

PubMed

Tam, Angela; Luedke, Angela C; Walsh, Jeremy J; Fernandez-Ruiz, Juan; Garcia, Angeles

2015-09-01

Variability in reaction time during task performance may reflect fluctuations in attention and cause reduced performance in goal-directed tasks, yet it is unclear whether the mechanisms behind this phenomenon change with age. Using fMRI, we tested young and cognitively healthy older adults with the Stroop task to determine whether aging affects the neural mechanisms underlying intra-individual reaction time variability. We found significant between-group differences in BOLD activity modulated by reaction time. In older adults, longer reaction times were associated with greater activity in frontoparietal attentional areas, while in younger adults longer reaction times were associated with greater activity in default mode network areas. Our results suggest that the neural correlates of reaction time variability change with healthy aging, reinforcing the concept of functional plasticity to maintain high cognitive function throughout the lifespan.

Analysis of Variability in HIV-1 Subtype A Strains in Russia Suggests a Combination of Deep Sequencing and Multitarget RNA Interference for Silencing of the Virus.

PubMed

Kretova, Olga V; Chechetkin, Vladimir R; Fedoseeva, Daria M; Kravatsky, Yuri V; Sosin, Dmitri V; Alembekov, Ildar R; Gorbacheva, Maria A; Gashnikova, Natalya M; Tchurikov, Nickolai A

2017-02-01

Any method for silencing the activity of the HIV-1 retrovirus should tackle the extremely high variability of HIV-1 sequences and mutational escape. We studied sequence variability in the vicinity of selected RNA interference (RNAi) targets from isolates of HIV-1 subtype A in Russia, and we propose that using artificial RNAi is a potential alternative to traditional antiretroviral therapy. We prove that using multiple RNAi targets overcomes the variability in HIV-1 isolates. The optimal number of targets critically depends on the conservation of the target sequences. The total number of targets that are conserved with a probability of 0.7-0.8 should exceed at least 2. Combining deep sequencing and multitarget RNAi may provide an efficient approach to cure HIV/AIDS.

Structure and dynamics of mixed-species flocks in a Hawaiian rain forest

USGS Publications Warehouse

Hart, P.J.; Freed, L.A.

2003-01-01

Mixed-species flocks of native and introduced birds were studied for four years in an upper elevation Hawaiian rain forest. Those flocks were characterized by strong seasonality, large size, low species richness, high intraspecific abundance, a lack of migrants, and a general lack of territoriality or any sort of dominance hierarchy. There was high variability among years in patterns of occurrence at the species level, and high variability within years at the individual level. These flocks are loosely structured social groupings with apparently open membership. The fluid, unstable movement patterns, high degree of variability in size and composition, and lack of positive interspecific associations are not consistent with the “foraging enhancement” hypothesis for flocking. Two resident, endangered insectivores, the Akepa (Loxops coccineus) and Hawaii Creeper (Oreomystis mana) served as “nuclear” species. Flock composition was compared between two study sites that differed significantly in density of these two nuclear species. Flock size was similar at the two sites, primarily because the nuclear species were over-represented relative to their density. This observation suggests that birds are attempting to achieve a more optimal flock size at the lower density site.

Characterizing the Optical Variability of Bright Blazars: Variability-based Selection of Fermi Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Ruan, John J.; Anderson, Scott F.; MacLeod, Chelsea L.; Becker, Andrew C.; Burnett, T. H.; Davenport, James R. A.; Ivezić, Željko; Kochanek, Christopher S.; Plotkin, Richard M.; Sesar, Branimir; Stuart, J. Scott

2012-11-01

We investigate the use of optical photometric variability to select and identify blazars in large-scale time-domain surveys, in part to aid in the identification of blazar counterparts to the ~30% of γ-ray sources in the Fermi 2FGL catalog still lacking reliable associations. Using data from the optical LINEAR asteroid survey, we characterize the optical variability of blazars by fitting a damped random walk model to individual light curves with two main model parameters, the characteristic timescales of variability τ, and driving amplitudes on short timescales \\hat{\\sigma }. Imposing cuts on minimum τ and \\hat{\\sigma } allows for blazar selection with high efficiency E and completeness C. To test the efficacy of this approach, we apply this method to optically variable LINEAR objects that fall within the several-arcminute error ellipses of γ-ray sources in the Fermi 2FGL catalog. Despite the extreme stellar contamination at the shallow depth of the LINEAR survey, we are able to recover previously associated optical counterparts to Fermi active galactic nuclei with E >= 88% and C = 88% in Fermi 95% confidence error ellipses having semimajor axis r < 8'. We find that the suggested radio counterpart to Fermi source 2FGL J1649.6+5238 has optical variability consistent with other γ-ray blazars and is likely to be the γ-ray source. Our results suggest that the variability of the non-thermal jet emission in blazars is stochastic in nature, with unique variability properties due to the effects of relativistic beaming. After correcting for beaming, we estimate that the characteristic timescale of blazar variability is ~3 years in the rest frame of the jet, in contrast with the ~320 day disk flux timescale observed in quasars. The variability-based selection method presented will be useful for blazar identification in time-domain optical surveys and is also a probe of jet physics.

Reducing Dropout in Treatment for Depression: Translating Dropout Predictors Into Individualized Treatment Recommendations.

PubMed

Zilcha-Mano, Sigal; Keefe, John R; Chui, Harold; Rubin, Avinadav; Barrett, Marna S; Barber, Jacques P

2016-12-01

Premature discontinuation of therapy is a widespread problem that hampers the delivery of mental health treatment. A high degree of variability has been found among rates of premature treatment discontinuation, suggesting that rates may differ depending on potential moderators. In the current study, our aim was to identify demographic and interpersonal variables that moderate the association between treatment assignment and dropout. Data from a randomized controlled trial conducted from November 2001 through June 2007 (N = 156) comparing supportive-expressive therapy, antidepressant medication, and placebo for the treatment of depression (based on DSM-IV criteria) were used. Twenty prerandomization variables were chosen based on previous literature. These variables were subjected to exploratory bootstrapped variable selection and included in the logistic regression models if they passed variable selection. Three variables were found to moderate the association between treatment assignment and dropout: age, pretreatment therapeutic alliance expectations, and the presence of vindictive tendencies in interpersonal relationships. When patients were divided into those randomly assigned to their optimal treatment and those assigned to their least optimal treatment, dropout rates in the optimal treatment group (24.4%) were significantly lower than those in the least optimal treatment group (47.4%; P = .03). Present findings suggest that a patient's age and pretreatment interpersonal characteristics predict the association between common depression treatments and dropout rate. If validated by further studies, these characteristics can assist in reducing dropout through targeted treatment assignment. Secondary analysis of data from ClinicalTrials.gov identifier: NCT00043550. © Copyright 2016 Physicians Postgraduate Press, Inc.

The associations of social self-control, personality disorders, and demographics with drug use among high-risk youth.

PubMed

Sussman, Steve; McCuller, William J; Dent, Clyde W

2003-08-01

A 10-item self-report measure of social self-control was examined for its association with substance use, controlling for its associations with 12 personality disorder indices and 4 demographic variables among a sample of 1050 high-risk youth. Social self-control was found to be associated with 30-day cigarette smoking, alcohol use, marijuana use, and hard drug use, controlling for these other variables. The most consistent concurrent predictors of substance use were male gender, antisocial personality disorder, and social self-control. These results highlight the importance of social self-control as a unique concurrent predictor of substance use and suggest that social self-control skill training is relevant in substance abuse prevention programming.

Effects of Escitalopram on Autonomic Function in Posttraumatic Stress Disorder Among Veterans of Operations Enduring Freedom and Iraqi Freedom (OEF/OIF).

PubMed

Ramaswamy, Sriram; Selvaraj, Vithyalakshmi; Driscoll, David; Madabushi, Jayakrishna S; Bhatia, Subhash C; Yeragani, Vikram

2015-01-01

Posttraumatic stress disorder is a chronic, debilitating condition that has become a growing concern among combat veterans. Previous research suggests that posttraumatic stress disorder disrupts normal autonomic responding and may increase the risk of cardiovascular disease and mortality. Measures of heart rate variability and QT interval variability have been used extensively to characterize sympathetic and parasympathetic influences on heart rate in a variety of psychiatric populations. The objective of this study was to better understand the effects of pharmacological treatment on autonomic reactivity in posttraumatic stress disorder. A 12-week, Phase IV, prospective, open-label trial of escitalopram in veterans with combat-related posttraumatic stress disorder and comorbid depression. An outpatient mental health clinic at a Veterans Affairs Medical Center. Eleven male veterans of Operations Enduring Freedom and Iraqi Freedom diagnosed with posttraumatic stress disorder and comorbid depression. Autonomic reactivity was measured by examining heart rate variability and QT interval variability. Treatment safety and efficacy were also evaluated pre- and post-treatment. We observed a reduction in posttraumatic stress disorder and depression symptoms from pre- to post-treatment, and escitalopram was generally well tolerated in our sample. In addition, we observed a decrease in high frequency heart rate variability and an increase in QT variability, indicating a reduction in cardiac vagal function and heightened sympathetic activation. These findings suggest that escitalopram treatment in patients with posttraumatic stress disorder and depression can trigger changes in autonomic reactivity that may adversely impact cardiovascular health.

Variability in spatio-temporal pattern of trapezius activity and coordination of hand-arm muscles during a sustained repetitive dynamic task.

PubMed

Samani, Afshin; Srinivasan, Divya; Mathiassen, Svend Erik; Madeleine, Pascal

2017-02-01

The spatio-temporal distribution of muscle activity has been suggested to be a determinant of fatigue development. Pursuing this hypothesis, we investigated the pattern of muscular activity in the shoulder and arm during a repetitive dynamic task performed until participants' rating of perceived exertion reached 8 on Borg's CR-10 scale. We collected high-density surface electromyogram (HD-EMG) over the upper trapezius, as well as bipolar EMG from biceps brachii, triceps brachii, deltoideus anterior, serratus anterior, upper and lower trapezius from 21 healthy women. Root-mean-square (RMS) and mean power frequency (MNF) were calculated for all EMG signals. The barycenter of RMS values over the HD-EMG grid was also determined, as well as normalized mutual information (NMI) for each pair of muscles. Cycle-to-cycle variability of these metrics was also assessed. With time, EMG RMS increased for most of the muscles, and MNF decreased. Trapezius activity became higher on the lateral side than on the medial side of the HD-EMG grid and the barycenter moved in a lateral direction. NMI between muscle pairs increased with time while its variability decreased. The variability of the metrics during the initial 10 % of task performance was not associated with the time to task termination. Our results suggest that the considerable variability in force and posture contained in the dynamic task per se masks any possible effects of differences between subjects in initial motor variability on the rate of fatigue development.

Evidence and mapping of extinction debts for global forest-dwelling reptiles, amphibians and mammals

NASA Astrophysics Data System (ADS)

Chen, Youhua; Peng, Shushi

2017-03-01

Evidence of extinction debts for the global distributions of forest-dwelling reptiles, mammals and amphibians was tested and the debt magnitude was estimated and mapped. By using different correlation tests and variable importance analysis, the results showed that spatial richness patterns for the three forest-dwelling terrestrial vertebrate groups had significant and stronger correlations with past forest cover area and other variables in the 1500 s, implying the evidence for extinction debts. Moreover, it was likely that the extinction debts have been partially paid, given that their global richness patterns were also significantly correlated with contemporary forest variables in the 2000 s (but the absolute magnitudes of the correlation coefficients were usually smaller than those calculated for historical forest variables). By utilizing species-area relationships, spatial extinction-debt magnitudes for the three vertebrate groups at the global scale were estimated and the hotspots of extinction debts were identified. These high-debt hotspots were generally situated in areas that did not spatially overlap with hotspots of species richness or high extinction-risk areas based on IUCN threatened status to a large extent. This spatial mismatch pattern suggested that necessary conservation efforts should be directed toward high-debt areas that are still overlooked.

Evidence and mapping of extinction debts for global forest-dwelling reptiles, amphibians and mammals.

PubMed

Chen, Youhua; Peng, Shushi

2017-03-16

Evidence of extinction debts for the global distributions of forest-dwelling reptiles, mammals and amphibians was tested and the debt magnitude was estimated and mapped. By using different correlation tests and variable importance analysis, the results showed that spatial richness patterns for the three forest-dwelling terrestrial vertebrate groups had significant and stronger correlations with past forest cover area and other variables in the 1500 s, implying the evidence for extinction debts. Moreover, it was likely that the extinction debts have been partially paid, given that their global richness patterns were also significantly correlated with contemporary forest variables in the 2000 s (but the absolute magnitudes of the correlation coefficients were usually smaller than those calculated for historical forest variables). By utilizing species-area relationships, spatial extinction-debt magnitudes for the three vertebrate groups at the global scale were estimated and the hotspots of extinction debts were identified. These high-debt hotspots were generally situated in areas that did not spatially overlap with hotspots of species richness or high extinction-risk areas based on IUCN threatened status to a large extent. This spatial mismatch pattern suggested that necessary conservation efforts should be directed toward high-debt areas that are still overlooked.

140-year subantarctic tree-ring temperature reconstruction reveals tropical forcing of increased Southern Ocean climate variability

NASA Astrophysics Data System (ADS)

Turney, C. S.; Fogwill, C. J.; Palmer, J. G.; VanSebille, E.; Thomas, Z.; McGlone, M.; Richardson, S.; Wilmshurst, J.; Fenwick, P.; Zunz, V.; Goosse, H.; Wilson, K. J.; Carter, L.; Lipson, M.; Jones, R. T.; Harsch, M.; Clark, G.; Marzinelli, E.; Rogers, T.; Rainsley, E.; Ciasto, L.; Waterman, S.; Thomas, E. R.; Visbeck, M.

2017-12-01

Occupying about 14 % of the world's surface, the Southern Ocean plays a fundamental role in ocean and atmosphere circulation, carbon cycling and Antarctic ice-sheet dynamics. Unfortunately, high interannual variability and a dearth of instrumental observations before the 1950s limits our understanding of how marine-atmosphere-ice domains interact on multi-decadal timescales and the impact of anthropogenic forcing. Here we integrate climate-sensitive tree growth with ocean and atmospheric observations on south-west Pacific subantarctic islands that lie at the boundary of polar and subtropical climates (52-54˚S). Our annually resolved temperature reconstruction captures regional change since the 1870s and demonstrates a significant increase in variability from the 1940s, a phenomenon predating the observational record, and coincident with major changes in mammalian and bird populations. Climate reanalysis and modelling show a parallel change in tropical Pacific sea surface temperatures that generate an atmospheric Rossby wave train which propagates across a large part of the Southern Hemisphere during the austral spring and summer. Our results suggest that modern observed high interannual variability was established across the mid-twentieth century, and that the influence of contemporary equatorial Pacific temperatures may now be a permanent feature across the mid- to high latitudes.

Perceived Discrimination and Mexican-Origin Young Adults' Sleep Duration and Variability: The Moderating Role of Cultural Orientations.

PubMed

Zeiders, Katharine H; Updegraff, Kimberly A; Kuo, Sally I-Chun; Umaña-Taylor, Adriana J; McHale, Susan M

2017-08-01

Perceived ethnic discrimination is central to the experiences of Latino young adults, yet we know little about the ways in which and the conditions under which ethnic discrimination relates to Latino young adults' sleep patterns. Using a sample of 246 Mexican-origin young adults (M age  = 21.11, SD = 1.54; 50 % female), the current study investigated the longitudinal links between perceived ethnic discrimination and both sleep duration and night-to-night variability in duration, while also examining the moderating roles of Anglo and Mexican orientations in the associations. The results revealed that perceived discrimination predicted greater sleep variability, and this link was not moderated by cultural orientations. The relation between perceived discrimination and hours of sleep, however, was moderated by Anglo and Mexican orientations. Individuals with high Anglo and Mexican orientations (bicultural) and those with only high Mexican orientations (enculturated), showed no association between discrimination and hours of sleep. Individuals with low Anglo and Mexican orientations (marginalized) displayed a positive association, whereas those with high Anglo and low Mexican orientations (acculturated) displayed a negative association. The results suggest that discrimination has long term effects on sleep variability of Mexican-origin young adults, regardless of cultural orientations; however, for sleep duration, bicultural and enculturated orientations are protective.

Using high-frequency sensors to identify hydroclimatological controls on storm-event variability in catchment nutrient fluxes and source zone activation

NASA Astrophysics Data System (ADS)

Blaen, Phillip; Khamis, Kieran; Lloyd, Charlotte; Krause, Stefan

2017-04-01

At the river catchment scale, storm events can drive highly variable behaviour in nutrient and water fluxes, yet short-term dynamics are frequently missed by low resolution sampling regimes. In addition, nutrient source contributions can vary significantly within and between storm events. Our inability to identify and characterise time dynamic source zone contributions severely hampers the adequate design of land use management practices in order to control nutrient exports from agricultural landscapes. Here, we utilise an 8-month high-frequency (hourly) time series of streamflow, nitrate concentration (NO3) and fluorescent dissolved organic matter concentration (FDOM) derived from optical in-situ sensors located in a headwater agricultural catchment. We characterised variability in flow and nutrient dynamics across 29 storm events. Storm events represented 31% of the time series and contributed disproportionately to nutrient loads (43% of NO3 and 36% of CDOM) relative to their duration. Principal components analysis of potential hydroclimatological controls on nutrient fluxes demonstrated that a small number of components, representing >90% of variance in the dataset, were highly significant model predictors of inter-event variability in catchment nutrient export. Hysteresis analysis of nutrient concentration-discharge relationships suggested spatially discrete source zones existed for NO3 and FDOM, and that activation of these zones varied on an event-specific basis. Our results highlight the benefits of high-frequency in-situ monitoring for characterising complex short-term nutrient dynamics and unravelling connections between hydroclimatological variability and river nutrient export and source zone activation under extreme flow conditions. These new process-based insights are fundamental to underpinning the development of targeted management measures to reduce nutrient loading of surface waters.

Major urinary protein (MUP) profiles show dynamic changes rather than individual ‘barcode’ signatures

PubMed Central

Thoß, M.; Luzynski, K.C.; Ante, M.; Miller, I.; Penn, D.J.

2016-01-01

House mice (Mus musculus) produce a variable number of major urinary proteins (MUPs), and studies suggest that each individual produces a unique MUP profile that provides a distinctive odor signature controlling individual and kin recognition. This ‘barcode hypothesis’ requires that MUP urinary profiles show high individual variability within populations and also high individual consistency over time, but tests of these assumptions are lacking. We analyzed urinary MUP profiles of 66 wild-caught house mice from eight populations using isoelectric focusing. We found that MUP profiles of wild male house mice are not individually unique, and though they were highly variable, closer inspection revealed that the variation strongly depended on MUP band type. The prominent (‘major) bands were surprisingly homogenous (and hence most MUPs are not polymorphic), but we also found inconspicuous (‘minor’) bands that were highly variable and therefore potential candidates for individual fingerprints. We also examined changes in urinary MUP profiles of 58 males over time (from 6 to 24 weeks of age), and found that individual MUP profiles and MUP concentration were surprisingly dynamic, and showed significant changes after puberty and during adulthood. Contrary to what we expected, however, the minor bands were the most variable over time, thus no good candidates for individual fingerprints. Although MUP profiles do not provide individual fingerprints, we found that MUP profiles were more similar among siblings than non-kin despite considerable fluctuation. Our findings show that MUP profiles are not highly stable over time, they do not show strong individual clustering, and thus challenge the barcode hypothesis. Within-individual dynamics of MUP profiles indicate a different function of MUPs in individual recognition than previously assumed and advocate an alternative hypothesis (‘dynamic changes’ hypothesis). PMID:26973837

Major urinary protein (MUP) profiles show dynamic changes rather than individual 'barcode' signatures.

PubMed

Thoß, M; Luzynski, K C; Ante, M; Miller, I; Penn, D J

2015-06-30

House mice ( Mus musculus) produce a variable number of major urinary proteins (MUPs), and studies suggest that each individual produces a unique MUP profile that provides a distinctive odor signature controlling individual and kin recognition. This 'barcode hypothesis' requires that MUP urinary profiles show high individual variability within populations and also high individual consistency over time, but tests of these assumptions are lacking. We analyzed urinary MUP profiles of 66 wild-caught house mice from eight populations using isoelectric focusing. We found that MUP profiles of wild male house mice are not individually unique, and though they were highly variable, closer inspection revealed that the variation strongly depended on MUP band type. The prominent ('major) bands were surprisingly homogenous (and hence most MUPs are not polymorphic), but we also found inconspicuous ('minor') bands that were highly variable and therefore potential candidates for individual fingerprints. We also examined changes in urinary MUP profiles of 58 males over time (from 6 to 24 weeks of age), and found that individual MUP profiles and MUP concentration were surprisingly dynamic, and showed significant changes after puberty and during adulthood. Contrary to what we expected, however, the minor bands were the most variable over time, thus no good candidates for individual fingerprints. Although MUP profiles do not provide individual fingerprints, we found that MUP profiles were more similar among siblings than non-kin despite considerable fluctuation. Our findings show that MUP profiles are not highly stable over time, they do not show strong individual clustering, and thus challenge the barcode hypothesis. Within-individual dynamics of MUP profiles indicate a different function of MUPs in individual recognition than previously assumed and advocate an alternative hypothesis ('dynamic changes' hypothesis).

Seasonal and diurnal variability in airborne mold from an indoor residential environment in northern New York.

PubMed

LeBouf, Ryan; Yesse, Liesel; Rossner, Alan

2008-05-01

It is well known that characterization of airborne bioaerosols in indoor environments is a challenge because of inherent irregularity in concentrations, which are influenced by many environmental factors. The primary aim of this study was to quantify the day-to-day variability of airborne fungal levels in a single residential environment over multiple seasons. Indoor air quality practitioners must recognize the inherent variability in airborne bio-aerosol measurements during data analysis of mold investigations. Changes in airborne fungi due to varying season and day is important to recognize when considering health impacts of these contaminants and when establishing effective controls. Using an Andersen N6 impactor, indoor and outdoor bioaerosol samples were collected on malt extract agar plates for 18 weekdays and 19 weekdays in winter and summer, respectively. Interday and intraday variability for the bioaerosols were determined for each sampler. Average fungal concentrations were 26 times higher during the summer months. Day-to-day fungal samples showed a relatively high inconsistency suggesting airborne fungal levels are very episodic and are influenced by several environmental factors. Summer bio-aerosol variability ranged from 7 to 36% and winter variability from 24 to 212%; these should be incorporated into results of indoor mold investigations. The second objective was to observe the relationship between biological and nonbiological particulate matter (PM). No correlation was observed between biological and nonbiological PM. Six side-by-side particulate samplers collected coarse PM (PM10) and fine PM (PM2.5) levels in both seasons. PM2.5 particulate concentrations were found to be statistically higher during summer months. Interday variability observed during this study suggests that indoor air quality practitioners must adjust their exposure assessment strategies to reflect the temporal variability in bioaerosol concentrations.

Effects of lakes and reservoirs on annual river nitrogen, phosphorus, and sediment export in agricultural and forested landscapes

USGS Publications Warehouse

Powers, Stephen M.; Robertson, Dale M.; Stanley, Emily H.

2014-01-01

Recently, effects of lakes and reservoirs on river nutrient export have been incorporated into landscape biogeochemical models. Because annual export varies with precipitation, there is a need to examine the biogeochemical role of lakes and reservoirs over time frames that incorporate interannual variability in precipitation. We examined long-term (~20 years) time series of river export (annual mass yield, Y, and flow-weighted mean annual concentration, C) for total nitrogen (TN), total phosphorus (TP), and total suspended sediment (TSS) from 54 catchments in Wisconsin, USA. Catchments were classified as small agricultural, large agricultural, and forested by use of a cluster analysis, and these varied in lentic coverage (percentage of catchment lake or reservoir water that was connected to river network). Mean annual export and interannual variability (CV) of export (for both Y and C) were higher in agricultural catchments relative to forested catchments for TP, TN, and TSS. In both agricultural and forested settings, mean and maximum annual TN yields were lower in the presence of lakes and reservoirs, suggesting lentic denitrification or N burial. There was also evidence of long-term lentic TP and TSS retention, especially when viewed in terms of maximum annual yield, suggesting sedimentation during high loading years. Lentic catchments had lower interannual variability in export. For TP and TSS, interannual variability in mass yield was often >50% higher than interannual variability in water yield, whereas TN variability more closely followed water (discharge) variability. Our results indicate that long-term mass export through rivers depends on interacting terrestrial, aquatic, and meteorological factors in which the presence of lakes and reservoirs can reduce the magnitude of export, stabilize interannual variability in export, as well as introduce export time lags.

Improved Sparse Multi-Class SVM and Its Application for Gene Selection in Cancer Classification

PubMed Central

Huang, Lingkang; Zhang, Hao Helen; Zeng, Zhao-Bang; Bushel, Pierre R.

2013-01-01

Background Microarray techniques provide promising tools for cancer diagnosis using gene expression profiles. However, molecular diagnosis based on high-throughput platforms presents great challenges due to the overwhelming number of variables versus the small sample size and the complex nature of multi-type tumors. Support vector machines (SVMs) have shown superior performance in cancer classification due to their ability to handle high dimensional low sample size data. The multi-class SVM algorithm of Crammer and Singer provides a natural framework for multi-class learning. Despite its effective performance, the procedure utilizes all variables without selection. In this paper, we propose to improve the procedure by imposing shrinkage penalties in learning to enforce solution sparsity. Results The original multi-class SVM of Crammer and Singer is effective for multi-class classification but does not conduct variable selection. We improved the method by introducing soft-thresholding type penalties to incorporate variable selection into multi-class classification for high dimensional data. The new methods were applied to simulated data and two cancer gene expression data sets. The results demonstrate that the new methods can select a small number of genes for building accurate multi-class classification rules. Furthermore, the important genes selected by the methods overlap significantly, suggesting general agreement among different variable selection schemes. Conclusions High accuracy and sparsity make the new methods attractive for cancer diagnostics with gene expression data and defining targets of therapeutic intervention. Availability: The source MATLAB code are available from http://math.arizona.edu/~hzhang/software.html. PMID:23966761

A high-density relativistic reflection origin for the soft and hard X-ray excess emission from Mrk 1044

NASA Astrophysics Data System (ADS)

Mallick, L.; Alston, W. N.; Parker, M. L.; Fabian, A. C.; Pinto, C.; Dewangan, G. C.; Markowitz, A.; Gandhi, P.; Kembhavi, A. K.; Misra, R.

2018-06-01

We present the first results from a detailed spectral-timing analysis of a long (˜130 ks) XMM-Newton observation and quasi-simultaneous NuSTAR and Swift observations of the highly-accreting narrow-line Seyfert 1 galaxy Mrk 1044. The broadband (0.3-50 keV) spectrum reveals the presence of a strong soft X-ray excess emission below ˜1.5 keV, iron Kα emission complex at ˜6 -7 keV and a `Compton hump' at ˜15 -30 keV. We find that the relativistic reflection from a high-density accretion disc with a broken power-law emissivity profile can simultaneously explain the soft X-ray excess, highly ionized broad iron line and the Compton hump. At low frequencies ([2 - 6] × 10-5 Hz), the power-law continuum dominated 1.5-5 keV band lags behind the reflection dominated 0.3-1 keV band, which is explained with a combination of propagation fluctuation and Comptonization processes, while at higher frequencies ([1 - 2] × 10-4 Hz), we detect a soft lag which is interpreted as a signature of X-ray reverberation from the accretion disc. The fractional root-mean-squared (rms) variability of the source decreases with energy and is well described by two variable components: a less variable relativistic disc reflection and a more variable direct coronal emission. Our combined spectral-timing analyses suggest that the observed broadband X-ray variability of Mrk 1044 is mainly driven by variations in the location or geometry of the optically thin, hot corona.

Variability, trends, and drivers of regional fluctuations in Australian fire activity

NASA Astrophysics Data System (ADS)

Earl, Nick; Simmonds, Ian

2017-07-01

Throughout the world fire regimes are determined by climate, vegetation, and anthropogenic factors, and they have great spatial and temporal variability. The availability of high-quality satellite data has revolutionized fire monitoring, allowing for a more consistent and comprehensive evaluation of temporal and spatial patterns. Here we utilize a satellite based "active fire" (AF) product to statistically analyze 2001-2015 variability and trends in Australian fire activity and link this to precipitation and large-scale atmospheric structures (namely, the El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD)) known to have potential for predicting fire activity in different regions. It is found that Australian fire activity is decreasing (during summer (December-February)) or stable, with high temporal and spatial variability. Eastern New South Wales (NSW) has the strongest decreasing trend (to the 1% confidence level), especially during the winter (JJA) season. Other significantly decreasing areas are Victoria/NSW, Tasmania, and South-east Queensland. These decreasing fire regions are relatively highly populated, so we suggest that the declining trends are due to improved fire management, reducing the size and duration of bush fires. Almost half of all Australian AFs occur during spring (September-November). We show that there is considerable potential throughout Australia for a skillful forecast for future season fire activity based on current and previous precipitation activity, ENSO phase, and to a lesser degree, the IOD phase. This is highly variable, depending on location, e.g., the IOD phase is for more indicative of fire activity in southwest Western Australia than for Queensland.

Evaluating Washington State's immunization information system as a research tool.

PubMed

Jackson, Michael L; Henrikson, Nora B; Grossman, David C

2014-01-01

Immunization information systems (IISs) are powerful public health tools for vaccination activities. To date, however, their use for public health research has been limited, in part as a result of insufficient understanding on accuracy and quality of IIS data. We evaluated the completeness and accuracy of Washington State IIS (WAIIS) data, with particular attention to data elements of research interest. We analyzed all WAIIS records on all children born between 2006 and 2010 with at least 1 vaccination recorded in WAIIS between 2006 and 2010. We assessed all variables for completeness and tested selected variables for internal validity. To assess external validity, we matched WAIIS data to records from Group Health, a large integrated health care organization in Washington State. On these children, we compared vaccination data in WAIIS with vaccination data from Group Health's immunization registry. The WAIIS data included 486,265 children and 8,670,234 unique vaccinations. Variables required by WAIIS (such as date of vaccination) were highly complete, but optional variables were often missing. For example, most records were missing data on route (80.7%) and anatomic site (81.7%) of vaccination. WAIIS data, when complete, were highly accurate relative to the Group Health immunization registry, with 96% to 99% agreement between fields such as vaccination code and anatomic site. Required data elements in WAIIS are highly complete and have both internal and external validity, suggesting that these variables are useful for research. Research requiring nonrequired variables should use additional validity checks before proceeding. Copyright © 2014 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.

Craniodental variation in Paranthropus boisei: a developmental and functional perspective.

PubMed

Wood, B; Lieberman, D E

2001-09-01

What levels and patterns of craniodental variation among a fossil hypodigm are necessary to reject the null hypothesis that only a single species is sampled? We suggest how developmental and functional criteria can be used to predict where in the skeleton of fossil hominins we should expect more, or less, within-species variation. We present and test three hypotheses about the factors contributing to craniodental variation in extant primate taxa, and then apply these results to the interpretation of the P. boisei hypodigm. Within the comparative samples of extant Homo, Pan, Gorilla, Pongo, and Colobus, variables from the cranial base, neurocranium, and face that are not subject to high magnitudes of strain have consistently lower levels of intraspecific variation than variables from regions of the face subject to high levels of strain. Dental size variables are intermediate in terms of their reliability. P. boisei is found to have a low degree of variability relative to extant primates for variables shown to be generally useful for testing taxonomic hypotheses. Contrary to the claims of Suwa et al. ([1997] Nature 389:489-492), the recently discovered material from Konso falls within the range of variation of the "pre-Konso" hypodigm of P. boisei for available conventional metrical variables. Those aspects of the Konso material that appear to extend the range of the P. boisei hypodigm involve regions of the skull predicted to be prone to high levels of within-species variation. The approach used in this study focuses on craniodental data, but it is applicable to other regions of the skeleton. Copyright 2001 Wiley-Liss, Inc.

Water supply, demand, and quality indicators for assessing the spatial distribution of water resource vulnerability in the Columbia River Basin

USGS Publications Warehouse

Chang, Heejun; Jung, Il-Won; Strecker, Angela L.; Wise, Daniel; Lafrenz, Martin; Shandas, Vivek; ,; Yeakley, Alan; Pan, Yangdong; Johnson, Gunnar; Psaris, Mike

2013-01-01

We investigated water resource vulnerability in the US portion of the Columbia River basin (CRB) using multiple indicators representing water supply, water demand, and water quality. Based on the US county scale, spatial analysis was conducted using various biophysical and socio-economic indicators that control water vulnerability. Water supply vulnerability and water demand vulnerability exhibited a similar spatial clustering of hotspots in areas where agricultural lands and variability of precipitation were high but dam storage capacity was low. The hotspots of water quality vulnerability were clustered around the main stem of the Columbia River where major population and agricultural centres are located. This multiple equal weight indicator approach confirmed that different drivers were associated with different vulnerability maps in the sub-basins of the CRB. Water quality variables are more important than water supply and water demand variables in the Willamette River basin, whereas water supply and demand variables are more important than water quality variables in the Upper Snake and Upper Columbia River basins. This result suggests that current water resources management and practices drive much of the vulnerability within the study area. The analysis suggests the need for increased coordination of water management across multiple levels of water governance to reduce water resource vulnerability in the CRB and a potentially different weighting scheme that explicitly takes into account the input of various water stakeholders.

Phylogenetic Analysis of Local-Scale Tree Soil Associations in a Lowland Moist Tropical Forest

PubMed Central

Schreeg, Laura A.; Kress, W. John; Erickson, David L.; Swenson, Nathan G.

2010-01-01

Background Local plant-soil associations are commonly studied at the species-level, while associations at the level of nodes within a phylogeny have been less well explored. Understanding associations within a phylogenetic context, however, can improve our ability to make predictions across systems and can advance our understanding of the role of evolutionary history in structuring communities. Methodology/Principal Findings Here we quantified evolutionary signal in plant-soil associations using a DNA sequence-based community phylogeny and several soil variables (e.g., extractable phosphorus, aluminum and manganese, pH, and slope as a proxy for soil water). We used published plant distributional data from the 50-ha plot on Barro Colorado Island (BCI), Republic of Panamá. Our results suggest some groups of closely related species do share similar soil associations. Most notably, the node shared by Myrtaceae and Vochysiaceae was associated with high levels of aluminum, a potentially toxic element. The node shared by Apocynaceae was associated with high extractable phosphorus, a nutrient that could be limiting on a taxon specific level. The node shared by the large group of Laurales and Magnoliales was associated with both low extractable phosphorus and with steeper slope. Despite significant node-specific associations, this study detected little to no phylogeny-wide signal. We consider the majority of the ‘traits’ (i.e., soil variables) evaluated to fall within the category of ecological traits. We suggest that, given this category of traits, phylogeny-wide signal might not be expected while node-specific signals can still indicate phylogenetic structure with respect to the variable of interest. Conclusions Within the BCI forest dynamics plot, distributions of some plant taxa are associated with local-scale differences in soil variables when evaluated at individual nodes within the phylogenetic tree, but they are not detectable by phylogeny-wide signal. Trends highlighted in this analysis suggest how plant-soil associations may drive plant distributions and diversity at the local-scale. PMID:21060686

Spatial Variability of Benthic-Pelagic Coupling in an Estuary Ecosystem: Consequences for Microphytobenthos Resuspension Phenomenon

PubMed Central

Ubertini, Martin; Lefebvre, Sébastien; Gangnery, Aline; Grangeré, Karine; Le Gendre, Romain; Orvain, Francis

2012-01-01

The high degree of physical factors in intertidal estuarine ecosystem increases material processing between benthic and pelagic compartments. In these ecosystems, microphytobenthos resuspension is a major phenomenon since its contribution to higher trophic levels can be highly significant. Understanding the sediment and associated microphytobenthos resuspension and its fate in the water column is indispensable for measuring the food available to benthic and pelagic food webs. To identify and hierarchize the physical/biological factors potentially involved in MPB resuspension, the entire intertidal area and surrounding water column of an estuarine ecosystem, the Bay des Veys, was sampled during ebb tide. A wide range of physical parameters (hydrodynamic regime, grain size of the sediment, and suspended matter) and biological parameters (flora and fauna assemblages, chlorophyll) were analyzed to characterize benthic-pelagic coupling at the bay scale. Samples were collected in two contrasted periods, spring and late summer, to assess the impact of forcing variables on benthic-pelagic coupling. A mapping approach using kriging interpolation enabled us to overlay benthic and pelagic maps of physical and biological variables, for both hydrological conditions and trophic indicators. Pelagic Chl a concentration was the best predictor explaining the suspension-feeders spatial distribution. Our results also suggest a perennial spatio-temporal structure of both benthic and pelagic compartments in the ecosystem, at least when the system is not imposed to intense wind, with MPB distribution controlled by both grain size and bathymetry. The benthic component appeared to control the pelagic one via resuspension phenomena at the scale of the bay. Co-inertia analysis showed closer benthic-pelagic coupling between the variables in spring. The higher MPB biomass observed in summer suggests a higher contribution to filter-feeders diets, indicating a higher resuspension effect in summer than in spring, in turn suggesting an important role of macrofauna bioturbation and filter feeding (Cerastoderma edule). PMID:22952910

Climate variability drives recent tree mortality in Europe.

PubMed

Neumann, Mathias; Mues, Volker; Moreno, Adam; Hasenauer, Hubert; Seidl, Rupert

2017-11-01

Tree mortality is an important process in forest ecosystems, frequently hypothesized to be highly climate sensitive. Yet, tree death remains one of the least understood processes of forest dynamics. Recently, changes in tree mortality have been observed in forests around the globe, which could profoundly affect ecosystem functioning and services provisioning to society. We describe continental-scale patterns of recent tree mortality from the only consistent pan-European forest monitoring network, identifying recent mortality hotspots in southern and northern Europe. Analyzing 925,462 annual observations of 235,895 trees between 2000 and 2012, we determine the influence of climate variability and tree age on interannual variation in tree mortality using Cox proportional hazard models. Warm summers as well as high seasonal variability in precipitation increased the likelihood of tree death. However, our data also suggest that reduced cold-induced mortality could compensate increased mortality related to peak temperatures in a warming climate. Besides climate variability, age was an important driver of tree mortality, with individual mortality probability decreasing with age over the first century of a trees life. A considerable portion of the observed variation in tree mortality could be explained by satellite-derived net primary productivity, suggesting that widely available remote sensing products can be used as an early warning indicator of widespread tree mortality. Our findings advance the understanding of patterns of large-scale tree mortality by demonstrating the influence of seasonal and diurnal climate variation, and highlight the potential of state-of-the-art remote sensing to anticipate an increased likelihood of tree mortality in space and time. © 2017 John Wiley & Sons Ltd.

Comparative Genome Analysis of Ciprofloxacin-Resistant Pseudomonas aeruginosa Reveals Genes Within Newly Identified High Variability Regions Associated With Drug Resistance Development

PubMed Central

Su, Hsun-Cheng; Khatun, Jainab; Kanavy, Dona M.

2013-01-01

The alarming rise of ciprofloxacin-resistant Pseudomonas aeruginosa has been reported in several clinical studies. Though the mutation of resistance genes and their role in drug resistance has been researched, the process by which the bacterium acquires high-level resistance is still not well understood. How does the genomic evolution of P. aeruginosa affect resistance development? Could the exposure of antibiotics to the bacteria enrich genomic variants that lead to the development of resistance, and if so, how are these variants distributed through the genome? To answer these questions, we performed 454 pyrosequencing and a whole genome analysis both before and after exposure to ciprofloxacin. The comparative sequence data revealed 93 unique resistance strain variation sites, which included a mutation in the DNA gyrase subunit A gene. We generated variation-distribution maps comparing the wild and resistant types, and isolated 19 candidates from three discrete resistance-associated high variability regions that had available transposon mutants, to perform a ciprofloxacin exposure assay. Of these region candidates with transposon disruptions, 79% (15/19) showed a reduction in the ability to gain high-level resistance, suggesting that genes within these high variability regions might enrich for certain functions associated with resistance development. PMID:23808957

A High-Resolution Biogenic Silica Record From Lake Titicaca, Peru-Bolivia: South American Millennial-Scale Climate Variability From 18-60 Kya

NASA Astrophysics Data System (ADS)

Ekdahl, E. J.; Fritz, S. C.; Stevens, L. R.; Baker, P. A.; Seltzer, G. O.

2004-12-01

Sediments recovered from a deep basin in Lake Titicaca, Peru-Boliva, were analyzed for biogenic silica (BSi) content by extraction of freeze dried sediments in 1% sodium carbonate. Sediments were dated using an age model developed from multiple 14C dates on bulk sediments. The BSi record shows distinct fluctuations in concentration and accumulation rate from 18 to 60 kya. Multi-taper method spectral analysis reveals a significant millennial-scale component to these fluctuations centered at 1370 years. High BSi accumulation rates correlate with enhanced benthic diatom preservation, suggesting that the BSi record is related to variations in lake water level. Modern-day Lake Titicaca lake level and precipitation are strongly related to northern equatorial Atlantic sea surface temperatures, with cooler SSTs related to wetter conditions. Subsequently, the spectral behavior of the GRIP ice core δ 18O record was investigated in order to estimate coherency and linkages between North Atlantic and tropical South American climate. GRIP data exhibit a significant 1370-year spectral peak which comprises approximately 26% of the total variability in the record. Despite a high degree of coherency between millennial-scale periodicities in Lake Titicaca BSi and GRIP δ 18O records, the Lake Titicaca silica record does not show longer term cooling cycles characteristic of D-O cycles found in the GRIP record. Rather, the Lake Titicaca record is highly periodic and more similar in nature to several Antarctic climate proxy records. These results suggest that while South American tropical climate varies in phase with North Atlantic climate, additional forcing mechanisms are manifest in the region which may include tropical Pacific and Southern Ocean variability.

Using present day observations to detect when ocean acidification exceeds natural variability of surface seawater Ωaragonite

NASA Astrophysics Data System (ADS)

Sutton, A.; Sabine, C. L.; Feely, R. A.

2016-02-01

One of the major challenges to assessing the impact of ocean acidification on marine life is the need to better understand the magnitude of long-term change in the context of natural variability. High-frequency moored observations can be highly effective in defining interannual, seasonal, and subseasonal variability at key locations. Here we present monthly aragonite saturation state (Ωaragonite) climatology for 15 open ocean, coastal, and coral reef locations using 3-hourly moored observations of surface seawater pCO2 and pH collected together since as early as 2009. We then use these present day surface mooring observations to estimate pre-industrial variability at each location and compare these results to previous modeling studies addressing global-scale variability and change. Our observations suggest that open oceans sites, especially in the subtropics, are experiencing Ωaragonite values throughout much of the year which are outside the range of pre-industrial values. In coastal and coral reef ecosystems, which have higher natural variability, seasonal patterns where present day Ωaragonite values exceeding pre-industrial bounds are emerging with some sites exhibiting subseasonal conditions approaching Ωaragonite = 1. Linking these seasonal patterns in carbonate chemistry to biological processes in these regions is critical to identify when and where marine life may encounter Ωaragonite values outside the conditions to which they have adapted.

Relationships between pediatric asthma and socioeconomic/urban variables in Baltimore, Maryland

NASA Technical Reports Server (NTRS)

Kimes, Daniel; Ullah, Asad; Levine, Elissa; Nelson, Ross; Timmins, Sidey; Weiss, Sheila; Bollinger, Mary E.; Blaisdell, Carol

2004-01-01

Spatial relationships between clinical data for pediatric asthmatics (hospital and emergency department utilization rates), and socioeconomic and urban characteristics in Baltimore City were analyzed with the aim of identifying factors that contribute to increased asthma rates. Socioeconomic variables and urban characteristics derived from satellite data explained 95% of the spatial variation in hospital rates. The proportion of families headed by a single female was the most important variable accounting for 89% of the spatial variation. Evidence suggests that the high rates of hospital admissions and emergency department (ED) visits may partially be due to the difficulty of single parents with limited resources managing their child's asthma condition properly. This knowledge can be used for education towards mitigating ED and hospital events in Baltimore City.

Can Process Understanding Help Elucidate The Structure Of The Critical Zone? Comparing Process-Based Soil Formation Models With Digital Soil Mapping.

NASA Astrophysics Data System (ADS)

Vanwalleghem, T.; Román, A.; Peña, A.; Laguna, A.; Giráldez, J. V.

2017-12-01

There is a need for better understanding the processes influencing soil formation and the resulting distribution of soil properties in the critical zone. Soil properties can exhibit strong spatial variation, even at the small catchment scale. Especially soil carbon pools in semi-arid, mountainous areas are highly uncertain because bulk density and stoniness are very heterogeneous and rarely measured explicitly. In this study, we explore the spatial variability in key soil properties (soil carbon stocks, stoniness, bulk density and soil depth) as a function of processes shaping the critical zone (weathering, erosion, soil water fluxes and vegetation patterns). We also compare the potential of traditional digital soil mapping versus a mechanistic soil formation model (MILESD) for predicting these key soil properties. Soil core samples were collected from 67 locations at 6 depths. Total soil organic carbon stocks were 4.38 kg m-2. Solar radiation proved to be the key variable controlling soil carbon distribution. Stone content was mostly controlled by slope, indicating the importance of erosion. Spatial distribution of bulk density was found to be highly random. Finally, total carbon stocks were predicted using a random forest model whose main covariates were solar radiation and NDVI. The model predicts carbon stocks that are double as high on north versus south-facing slopes. However, validation showed that these covariates only explained 25% of the variation in the dataset. Apparently, present-day landscape and vegetation properties are not sufficient to fully explain variability in the soil carbon stocks in this complex terrain under natural vegetation. This is attributed to a high spatial variability in bulk density and stoniness, key variables controlling carbon stocks. Similar results were obtained with the mechanistic soil formation model MILESD, suggesting that more complex models might be needed to further explore this high spatial variability.

Seasonal and Interannual Variabilities in Tropical Tropospheric Ozone

NASA Technical Reports Server (NTRS)

Ziemke, J. R.; Chandra, S.

1999-01-01

This paper presents a detailed characterization of seasonal and interannual variability in tropical tropospheric column ozone (TCO). TCO time series are derived from 20 years (1979-1998) of total ozone mapping spectrometer (TOMS) data using the convective cloud differential (CCD) method. Our study identifies three regions in the tropics with distinctly different zonal characteristics related to seasonal and interannual variability. These three regions are the eastern Pacific, Atlantic, and western Pacific. Results show that in both the eastern and western Pacific seasonal-cycle variability of northern hemisphere (NH) TCO exhibits maximum amount during NH spring whereas largest amount in southern hemisphere (SH) TCO occurs during SH spring. In the Atlantic, maximum TCO in both hemispheres occurs in SH spring. These seasonal cycles are shown to be comparable to seasonal cycles present in ground-based ozonesonde measurements. Interannual variability in the Atlantic region indicates a quasi-biennial oscillation (QBO) signal that is out of phase with the QBO present in stratospheric column ozone (SCO). This is consistent with high pollution and high concentrations of mid-to-upper tropospheric O3-producing precursors in this region. The out of phase relation suggests a UV modulation of tropospheric photochemistry caused by the QBO in stratospheric O3. During El Nino events there is anomalously low TCO in the eastern Pacific and high values in the western Pacific, indicating the effects of convectively-driven transport of low-value boundary layer O3 (reducing TCO) and O3 precursors including H2O and OH. A simplified technique is proposed to derive high-resolution maps of TCO in the tropics even in the absence of tropopause-level clouds. This promising approach requires only total ozone gridded measurements and utilizes the small variability observed in TCO near the dateline. This technique has an advantage compared to the CCD method because the latter requires high-resolution footprint measurements of both reflectivity and total ozone in the presence of tropopause-level cloud tops.

Statistical modeling of the Internet traffic dynamics: To which extent do we need long-term correlations?

NASA Astrophysics Data System (ADS)

Markelov, Oleg; Nguyen Duc, Viet; Bogachev, Mikhail

2017-11-01

Recently we have suggested a universal superstatistical model of user access patterns and aggregated network traffic. The model takes into account the irregular character of end user access patterns on the web via the non-exponential distributions of the local access rates, but neglects the long-term correlations between these rates. While the model is accurate for quasi-stationary traffic records, its performance under highly variable and especially non-stationary access dynamics remains questionable. In this paper, using an example of the traffic patterns from a highly loaded network cluster hosting the website of the 1998 FIFA World Cup, we suggest a generalization of the previously suggested superstatistical model by introducing long-term correlations between access rates. Using queueing system simulations, we show explicitly that this generalization is essential for modeling network nodes with highly non-stationary access patterns, where neglecting long-term correlations leads to the underestimation of the empirical average sojourn time by several decades under high throughput utilization.

An X-ray survey of variable radio bright quasars

NASA Technical Reports Server (NTRS)

Henriksen, M. J.; Marshall, F. E.; Mushotzky, R. F.

1984-01-01

A sample consisting primarily of radio bright quasars was observed in X-rays with the Einstein Observatory for times ranging from 1500 to 5000 seconds. Detected sources had luminosities ranging from 0.2 to 41.0 x 10 to the 45th power ergs/sec in the 0.5 to 4.5 keV band. Three of the fourteen objects which were reobserved showed flux increases greater than a factor of two on a time scale greater than six months. No variability was detected during the individual observations. The optical and X-ray luminosities are correlated, which suggests a common origin. However, the relationship (L sub x is approximately L sub op to the (.89 + or - .15)) found for historic radio variables may be significantly different than that reported for other radio bright sources. Some of the observed X-ray fluxes were substantially below the predicted self-Compton flux, assuming incoherent synchrotron emission and using VLBI results to constrain the size of the emission region, which suggests relativistic expansion in these sources. Normal CIV emission in two of the sources with an overpredicted Compton component suggests that although they, like BL Lac objects, have highly relativistic material apparently moving at small angle to the line of sight, they have a smaller fraction of the continuum component in the beam.

The Pattern of Genetic Variability in Apomictic Clones of Taraxacum officinale Indicates the Alternation of Asexual and Sexual Histories of Apomicts

PubMed Central

Majeský, Ľuboš; Vašut, Radim J.; Kitner, Miloslav; Trávníček, Bohumil

2012-01-01

Dandelions (genus Taraxacum) comprise a group of sexual diploids and apomictic polyploids with a complicated reticular evolution. Apomixis (clonal reproduction through seeds) in this genus is considered to be obligate, and therefore represent a good model for studying the role of asexual reproduction in microevolutionary processes of apomictic genera. In our study, a total of 187 apomictic individuals composing a set of nine microspecies (sampled across wide geographic area in Europe) were genotyped for six microsatellite loci and for 162 amplified fragment length polymorphism (AFLP) markers. Our results indicated that significant genetic similarity existed within accessions with low numbers of genotypes. Genotypic variability was high among accessions but low within accessions. Clustering methods discriminated individuals into nine groups corresponding to their phenotypes. Furthermore, two groups of apomictic genotypes were observed, which suggests that they had different asexual histories. A matrix compatibility test suggests that most of the variability within accession groups was mutational in origin. However, the presence of recombination was also detected. The accumulation of mutations in asexual clones leads to the establishment of a network of clone mates. However, this study suggests that the clones primarily originated from the hybridisation between sexual and apomicts. PMID:22870257

Glacial forcing of central Indonesian hydroclimate since 60,000 y B.P.

PubMed Central

Russell, James M.; Vogel, Hendrik; Konecky, Bronwen L.; Bijaksana, Satria; Huang, Yongsong; Melles, Martin; Wattrus, Nigel; Costa, Kassandra; King, John W.

2014-01-01

The Indo-Pacific warm pool houses the largest zone of deep atmospheric convection on Earth and plays a critical role in global climate variations. Despite the region’s importance, changes in Indo-Pacific hydroclimate on orbital timescales remain poorly constrained. Here we present high-resolution geochemical records of surface runoff and vegetation from sediment cores from Lake Towuti, on the island of Sulawesi in central Indonesia, that continuously span the past 60,000 y. We show that wet conditions and rainforest ecosystems on Sulawesi present during marine isotope stage 3 (MIS3) and the Holocene were interrupted by severe drying between ∼33,000 and 16,000 y B.P. when Northern Hemisphere ice sheets expanded and global temperatures cooled. Our record reveals little direct influence of precessional orbital forcing on regional climate, and the similarity between MIS3 and Holocene climates observed in Lake Towuti suggests that exposure of the Sunda Shelf has a weaker influence on regional hydroclimate and terrestrial ecosystems than suggested previously. We infer that hydrological variability in this part of Indonesia varies strongly in response to high-latitude climate forcing, likely through reorganizations of the monsoons and the position of the intertropical convergence zone. These findings suggest an important role for the tropical western Pacific in amplifying glacial–interglacial climate variability. PMID:24706841

Evaluation of solar irradiance models for climate studies

NASA Astrophysics Data System (ADS)

Ball, William; Yeo, Kok-Leng; Krivova, Natalie; Solanki, Sami; Unruh, Yvonne; Morrill, Jeff

2015-04-01

Instruments on satellites have been observing both Total Solar Irradiance (TSI) and Spectral Solar Irradiance (SSI), mainly in the ultraviolet (UV), since 1978. Models were developed to reproduce the observed variability and to compute the variability at wavelengths that were not observed or had an uncertainty too high to determine an accurate rotational or solar cycle variability. However, various models and measurements show different solar cycle SSI variability that lead to different modelled responses of ozone and temperature in the stratosphere, mainly due to the different UV variability in each model, and the global energy balance. The NRLSSI and SATIRE-S models are the most comprehensive reconstructions of solar irradiance variability for the period from 1978 to the present day. But while NRLSSI and SATIRE-S show similar solar cycle variability below 250 nm, between 250 and 400 nm SATIRE-S typically displays 50% larger variability, which is however, still significantly less then suggested by recent SORCE data. Due to large uncertainties and inconsistencies in some observational datasets, it is difficult to determine in a simple way which model is likely to be closer to the true solar variability. We review solar irradiance variability measurements and modelling and employ new analysis that sheds light on the causes of the discrepancies between the two models and with the observations.

Coronae on stars

NASA Technical Reports Server (NTRS)

Haisch, B. M.

1986-01-01

Three lines of evidence are noted to point to a flare heating source for stellar coronae: a strong correlation between time-averaged flare energy release and coronal X-ray luminosity, the high temperature flare-like component of the spectral signature of coronal X-ray emission, and the observed short time scale variability that indicates continuous flare activity. It is presently suggested that flares may represent only the extreme high energy tail of a continuous distribution of coronal energy release events.

Prompt optical emission from gamma-ray bursts with multiple timescale variability of central engine activities

NASA Astrophysics Data System (ADS)

Xu, Si-Yao; Li, Zhuo

2014-04-01

Complete high-resolution light curves of GRB 080319B observed by Swift present an opportunity for detailed temporal analysis of prompt optical emission. With a two-component distribution of initial Lorentz factors, we simulate the dynamical process of shells being ejected from the central engine in the framework of the internal shock model. The emitted radiations are decomposed into different frequency ranges for a temporal correlation analysis between the light curves in different energy bands. The resulting prompt optical and gamma-ray emissions show similar temporal profiles, with both showing a superposition of a component with slow variability and a component with fast variability, except that the gamma-ray light curve is much more variable than its optical counterpart. The variability in the simulated light curves and the strong correlation with a time lag between the optical and gamma-ray emissions are in good agreement with observations of GRB 080319B. Our simulations suggest that the variations seen in the light curves stem from the temporal structure of the shells injected from the central engine of gamma-ray bursts. Future observations with high temporal resolution of prompt optical emission from GRBs, e.g., by UFFO-Pathfinder and SVOM-GWAC, will provide a useful tool for investigating the central engine activity.

Bacterial Biogeography across the Amazon River-Ocean Continuum

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

Doherty, Mary; Yager, Patricia L.; Moran, Mary Ann

Spatial and temporal patterns in microbial biodiversity across the Amazon river-ocean continuum were investigated along ~675 km of the lower Amazon River mainstem, in the Tapajos River tributary, and in the plume and coastal ocean during low and high river discharge using amplicon sequencing of 16S rRNA genes in whole water and size-fractionated samples (0.2-2.0 μm and >2.0 μm). River communities varied among tributaries, but mainstem communities were spatially homogeneous and tracked seasonal changes in river discharge and co-varying factors. Co-occurrence network analysis identified strongly interconnected river assemblages during high (May) and low (December) discharge periods, and weakly interconnected transitionalmore » assemblages in September, suggesting that this system supports two seasonal microbial communities linked to river discharge. In contrast, plume communities showed little seasonal differences and instead varied spatially tracking salinity. However, salinity explained only a small fraction of community variability, and plume communities in blooms of diatom-diazotroph assemblages were strikingly different than those in other high salinity plume samples. This suggests that while salinity physically structures plumes through buoyancy and mixing, the composition of plume-specific communities is controlled by other factors including nutrients, phytoplankton community composition, and dissolved organic matter chemistry. Co-occurrence networks identified interconnected assemblages associated with the highly productive low salinity nearshore region, diatom-diazotroph blooms, and the plume edge region, and weakly interconnected assemblages in high salinity regions. This suggests that the plume supports a transitional community influenced by immigration of ocean bacteria from the plume edge, and by species sorting as these communities adapt to local environmental conditions. Few studies have explored patterns of microbial diversity in tropical rivers and coastal oceans. Comparison of Amazon continuum microbial communities to those from temperate and arctic systems suggest that river discharge and salinity are master variables structuring a range of environmental conditions that control bacterial communities across the river-ocean continuum.« less

Bacterial Biogeography across the Amazon River-Ocean Continuum.

PubMed

Doherty, Mary; Yager, Patricia L; Moran, Mary Ann; Coles, Victoria J; Fortunato, Caroline S; Krusche, Alex V; Medeiros, Patricia M; Payet, Jérôme P; Richey, Jeffrey E; Satinsky, Brandon M; Sawakuchi, Henrique O; Ward, Nicholas D; Crump, Byron C

2017-01-01

Spatial and temporal patterns in microbial biodiversity across the Amazon river-ocean continuum were investigated along ∼675 km of the lower Amazon River mainstem, in the Tapajós River tributary, and in the plume and coastal ocean during low and high river discharge using amplicon sequencing of 16S rRNA genes in whole water and size-fractionated samples (0.2-2.0 μm and >2.0 μm). River communities varied among tributaries, but mainstem communities were spatially homogeneous and tracked seasonal changes in river discharge and co-varying factors. Co-occurrence network analysis identified strongly interconnected river assemblages during high (May) and low (December) discharge periods, and weakly interconnected transitional assemblages in September, suggesting that this system supports two seasonal microbial communities linked to river discharge. In contrast, plume communities showed little seasonal differences and instead varied spatially tracking salinity. However, salinity explained only a small fraction of community variability, and plume communities in blooms of diatom-diazotroph assemblages were strikingly different than those in other high salinity plume samples. This suggests that while salinity physically structures plumes through buoyancy and mixing, the composition of plume-specific communities is controlled by other factors including nutrients, phytoplankton community composition, and dissolved organic matter chemistry. Co-occurrence networks identified interconnected assemblages associated with the highly productive low salinity near-shore region, diatom-diazotroph blooms, and the plume edge region, and weakly interconnected assemblages in high salinity regions. This suggests that the plume supports a transitional community influenced by immigration of ocean bacteria from the plume edge, and by species sorting as these communities adapt to local environmental conditions. Few studies have explored patterns of microbial diversity in tropical rivers and coastal oceans. Comparison of Amazon continuum microbial communities to those from temperate and arctic systems suggest that river discharge and salinity are master variables structuring a range of environmental conditions that control bacterial communities across the river-ocean continuum.

Bacterial Biogeography across the Amazon River-Ocean Continuum

DOE PAGES

Doherty, Mary; Yager, Patricia L.; Moran, Mary Ann; ...

2017-05-23

Spatial and temporal patterns in microbial biodiversity across the Amazon river-ocean continuum were investigated along ~675 km of the lower Amazon River mainstem, in the Tapajos River tributary, and in the plume and coastal ocean during low and high river discharge using amplicon sequencing of 16S rRNA genes in whole water and size-fractionated samples (0.2-2.0 μm and >2.0 μm). River communities varied among tributaries, but mainstem communities were spatially homogeneous and tracked seasonal changes in river discharge and co-varying factors. Co-occurrence network analysis identified strongly interconnected river assemblages during high (May) and low (December) discharge periods, and weakly interconnected transitionalmore » assemblages in September, suggesting that this system supports two seasonal microbial communities linked to river discharge. In contrast, plume communities showed little seasonal differences and instead varied spatially tracking salinity. However, salinity explained only a small fraction of community variability, and plume communities in blooms of diatom-diazotroph assemblages were strikingly different than those in other high salinity plume samples. This suggests that while salinity physically structures plumes through buoyancy and mixing, the composition of plume-specific communities is controlled by other factors including nutrients, phytoplankton community composition, and dissolved organic matter chemistry. Co-occurrence networks identified interconnected assemblages associated with the highly productive low salinity nearshore region, diatom-diazotroph blooms, and the plume edge region, and weakly interconnected assemblages in high salinity regions. This suggests that the plume supports a transitional community influenced by immigration of ocean bacteria from the plume edge, and by species sorting as these communities adapt to local environmental conditions. Few studies have explored patterns of microbial diversity in tropical rivers and coastal oceans. Comparison of Amazon continuum microbial communities to those from temperate and arctic systems suggest that river discharge and salinity are master variables structuring a range of environmental conditions that control bacterial communities across the river-ocean continuum.« less

Bacterial Biogeography across the Amazon River-Ocean Continuum

PubMed Central

Doherty, Mary; Yager, Patricia L.; Moran, Mary Ann; Coles, Victoria J.; Fortunato, Caroline S.; Krusche, Alex V.; Medeiros, Patricia M.; Payet, Jérôme P.; Richey, Jeffrey E.; Satinsky, Brandon M.; Sawakuchi, Henrique O.; Ward, Nicholas D.; Crump, Byron C.

2017-01-01

Spatial and temporal patterns in microbial biodiversity across the Amazon river-ocean continuum were investigated along ∼675 km of the lower Amazon River mainstem, in the Tapajós River tributary, and in the plume and coastal ocean during low and high river discharge using amplicon sequencing of 16S rRNA genes in whole water and size-fractionated samples (0.2–2.0 μm and >2.0 μm). River communities varied among tributaries, but mainstem communities were spatially homogeneous and tracked seasonal changes in river discharge and co-varying factors. Co-occurrence network analysis identified strongly interconnected river assemblages during high (May) and low (December) discharge periods, and weakly interconnected transitional assemblages in September, suggesting that this system supports two seasonal microbial communities linked to river discharge. In contrast, plume communities showed little seasonal differences and instead varied spatially tracking salinity. However, salinity explained only a small fraction of community variability, and plume communities in blooms of diatom-diazotroph assemblages were strikingly different than those in other high salinity plume samples. This suggests that while salinity physically structures plumes through buoyancy and mixing, the composition of plume-specific communities is controlled by other factors including nutrients, phytoplankton community composition, and dissolved organic matter chemistry. Co-occurrence networks identified interconnected assemblages associated with the highly productive low salinity near-shore region, diatom-diazotroph blooms, and the plume edge region, and weakly interconnected assemblages in high salinity regions. This suggests that the plume supports a transitional community influenced by immigration of ocean bacteria from the plume edge, and by species sorting as these communities adapt to local environmental conditions. Few studies have explored patterns of microbial diversity in tropical rivers and coastal oceans. Comparison of Amazon continuum microbial communities to those from temperate and arctic systems suggest that river discharge and salinity are master variables structuring a range of environmental conditions that control bacterial communities across the river-ocean continuum. PMID:28588561

Brief Report: Discrimination of Foreign Speech Pitch and Autistic Traits in Non-Clinical Population

ERIC Educational Resources Information Center

Iao, Lai-Sang; Wippich, Anna; Lam, Yu Hin

2018-01-01

Individuals with Autism Spectrum Conditions (ASC) are widely suggested to show enhanced perceptual discrimination but inconsistent findings have been reported for pitch discrimination. Given the high variability in ASC, this study investigated whether ASC traits were correlated with pitch discrimination in an undergraduate sample when musical and…

Effects of irrigation frequency and grit color on the germination of lodgepole pine seeds

Treesearch

Jeremy R. Pinto; R. Kasten Dumroese; Douglas R. Cobos

2009-01-01

Nursery cultural practices during germination can be highly variable between existing production facilities. Although nursery guidebooks suggest keeping seeds moist, there are no known scientific answers indicating what sufficient moisture levels are. This study objective was to characterize differing irrigation regimes and grit color choices on different germination...

Improving Surface Flux Parameterizations in the NRL Coupled Ocean/Atmosphere Mesoscale Prediction System

DTIC Science & Technology

2008-09-30

these days from a suite of instruments were analyzed, including those from rawinsonde launches, acoustic radar, and the 20 m flux tower. The objective...aircraft IR pyrometer in CBLAST-Low on (c) August 18, and (d) August 25, 2003. The NCOM simulation suggests that the high SST variability observed on

Benthic iron cycling in a high-oxygen environment: Implications for interpreting the Archean sedimentary iron isotope record.

PubMed

McCoy, V E; Asael, D; Planavsky, N

2017-09-01

The most notable trend in the sedimentary iron isotope record is a shift at the end of the Archean from highly variable δ 56 Fe values with large negative excursions to less variable δ 56 Fe values with more limited negative values. The mechanistic explanation behind this trend has been extensively debated, with two main competing hypotheses: (i) a shift in marine redox conditions and the transition to quantitative iron oxidation; and (ii) a decrease in the signature of microbial iron reduction in the sedimentary record because of increased bacterial sulfate reduction (BSR). Here, we provide new insights into this debate and attempt to assess these two hypotheses by analyzing the iron isotope composition of siderite concretions from the Carboniferous Mazon Creek fossil site. These concretions precipitated in an environment with water column oxygenation, extensive sediment pile dissimilatory iron reduction (DIR) but limited bacterial sulfate reduction (BSR). Most of the concretions have slightly positive iron isotope values, with a mean of 0.15‰ and limited iron isotope variability compared to the Archean sedimentary record. This limited variability in an environment with high DIR and low BSR suggests that these conditions alone are insufficient to explain Archean iron isotope compositions. Therefore, these results support the idea that the unusually variable and negative iron isotope values in the Archean are due to dissimilatory iron reduction (DIR) coupled with extensive water column iron cycling. © 2017 John Wiley & Sons Ltd.

Gratitude is associated with greater levels of protective factors and lower levels of risks in African American adolescents.

PubMed

Ma, Mindy; Kibler, Jeffrey L; Sly, Kaye

2013-10-01

The literature suggests gratitude is associated with positive youth development. The current study examined the relationship between gratitude and protective/risk factors among African American youth. Adolescents (N = 389; 50.4% males) ages 12-14 completed measures of gratitude (moral affect and life-orientation), protective factors (e.g., academic and activity engagement, family relationship), and high-risk behaviors (e.g., sexual attitudes and behaviors, drug/alcohol use). Results indicated greater moral affect gratitude was the only variable significantly associated with greater academic interest, better academic performance, and more extra-curricular activity engagement. Greater moral affect and life-orientation gratitude both significantly correlated with positive family relationship. Greater life-orientation gratitude was the only variable significantly associated with abstinence from sexual intimacy, sexual intercourse, likelihood of engaging in sex during primary school, and abstinence from drug/alcohol use. The findings suggest that moral affect gratitude may enhance protective factors while life-orientation gratitude may buffer against high-risk behaviors among African American youth. Copyright © 2013 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

Association between the triglyceride to high-density lipoprotein cholesterol ratio and insulin resistance in Korean adolescents: a nationwide population-based study.

PubMed

Park, Jae-Min; Lee, Jee-Yon; Dong, Jae June; Lee, Duk-Chul; Lee, Yong-Jae

2016-11-01

Studies have suggested the triglyceride to high-density lipoprotein cholesterol ratio (TG/HDL-C) as a surrogate marker of insulin resistance. However, few studies have examined the association between TG/HDL-C and insulin resistance in the general adolescent population. This study aimed to examine the association between TG/HDL-C and insulin resistance in a nationally representative sample of Korean adolescents. A total of 2649 participants aged 12-18 years were selected from the 2007 to 2010 Korean National Health and Nutrition Examination Survey (KNHANES). Insulin resistance was defined as the homeostatic model assessment of insulin resistance (HOMA-IR) values greater than the 80th percentile. The mean values of most cardiometabolic variables increased proportionally with TG/HDL-C quartiles. Compared to individuals in the lowest TG/HDL-C quartile, the odds ratio for insulin resistance for individuals in the highest quartile was 2.91 in boys and 2.38 in girls after adjusting for confounding variables. This study suggests that TG/HDL-C could be a convenient marker for identifying Korean adolescents with insulin resistance.

The relationship between Arabian Sea upwelling and Indian monsoon revisited

NASA Astrophysics Data System (ADS)

Yi, X.; Hünicke, B.; Tim, N.; Zorita, E.

2015-11-01

Studies based on upwelling indices (sediment records, sea-surface temperature and wind) suggest that upwelling along the western coast of Arabian Sea is strongly affected by the Indian summer monsoon (ISM). In order to examine this relationship directly, we employ the vertical water mass transport produced by the eddy-resolving global ocean simulation STORM driven by meteorological reanalysis over the last 61 years. With its very high spatial resolution (10 km), STORM allows us to identify characteristics of the upwelling system. We analyze the co-variability between upwelling and meteorological and oceanic variables from 1950 to 2010. The analyses reveal high interannual correlations between coastal upwelling and along-shore wind-stress (r=0.73) as well as with sea-surface temperature (r0.83). However, the correlation between the upwelling and the ISM is small and other factors might contribute to the upwelling variability. In addition, no long-term trend is detected in our modeled upwelling time series.

Delta Scuti Variables

NASA Astrophysics Data System (ADS)

Handler, Gerald

2009-09-01

We review recent research on Delta Scuti stars from an observer's viewpoint. First, some signposts helping to find the way through the Delta Scuti jungle are placed. Then, some problems in studying individual pulsators in the framework of asteroseismology are given before a view on how the study of these variables has benefited (or not) from past and present high-precision asteroseismic space missions is presented. Some possible pitfalls in the analysis of data with a large dynamical range in pulsational amplitudes are pointed out, and a strategy to optimize the outcome of asteroseismic studies of Delta Scuti stars is suggested. We continue with some views on ``hybrid'' pulsators and interesting individual High Amplitude Delta Scuti stars, and then take a look on Delta Scuti stars in stellar systems of several different kinds. Recent results on pre-main sequence Delta Scuti stars are discussed as are questions related to the instability strip of these variables. Finally, some remarkable new theoretical results are highlighted before, instead of a set of classical conclusions, questions to be solved in the future, are raised.

Metabolic Capacity of Sinorhizobium (Ensifer) meliloti Strains as Determined by Phenotype MicroArray Analysis▿ †

PubMed Central

Biondi, Emanuele G.; Tatti, Enrico; Comparini, Diego; Giuntini, Elisa; Mocali, Stefano; Giovannetti, Luciana; Bazzicalupo, Marco; Mengoni, Alessio; Viti, Carlo

2009-01-01

Sinorhizobium meliloti is a soil bacterium that fixes atmospheric nitrogen in plant roots. The high genetic diversity of its natural populations has been the subject of extensive analysis. Recent genomic studies of several isolates revealed a high content of variable genes, suggesting a correspondingly large phenotypic differentiation among strains of S. meliloti. Here, using the Phenotype MicroArray (PM) system, hundreds of different growth conditions were tested in order to compare the metabolic capabilities of the laboratory reference strain Rm1021 with those of four natural S. meliloti isolates previously analyzed by comparative genomic hybridization (CGH). The results of PM analysis showed that most phenotypic differences involved carbon source utilization and tolerance to osmolytes and pH, while fewer differences were scored for nitrogen, phosphorus, and sulfur source utilization. Only the variability of the tested strain in tolerance to sodium nitrite and ammonium sulfate of pH 8 was hypothesized to be associated with the genetic polymorphisms detected by CGH analysis. Colony and cell morphologies and the ability to nodulate Medicago truncatula plants were also compared, revealing further phenotypic diversity. Overall, our results suggest that the study of functional (phenotypic) variability of S. meliloti populations is an important and complementary step in the investigation of genetic polymorphism of rhizobia and may help to elucidate rhizobial evolutionary dynamics, including adaptation to diverse environments. PMID:19561177

Geochemistry and petrogenesis of serpentinite from the Ingalls ophiolite complex, central Cascades, Washington

NASA Astrophysics Data System (ADS)

MacDonald, J. H., Jr.; Milliken, S. H.; Zalud, K. M.

2017-12-01

The Jurassic Ingalls ophiolite complex is located in the central Cascades, Washington State. This ophiolite predominantly consists of three variably serpentinized mantle units. Serpentinite occurs as massive replacing peridotite, or as highly sheared fault zones cutting other rocks. Mylonitic serpentinite forms a large-scale mélange in the middle of the ophiolite, and is interpreted as a fracture zone. Whole-rock and mineral geochemistry of the massive serpentinite was done to understand the metasomatic process and identify the possible protoliths of these rocks. Whole-rock major and trace elements of the massive serpentinite are similar to modern peridotites. The majority of samples analyzed are strongly serpentinized, while a few were moderately to weakly altered. Ca, Mg, and Al suggest these rocks formed from serpentinized harzburgite and dunite with minor lherzolite. All samples have positive Eu/Eu*. Serpentinites plot in fields defined by modern abyssal and forearc peridotites. Trace elements suggests the protoliths underwent variable amounts of mantel depletion (5-20%). Serpentine and relic igneous minerals were analyzed by EPMA at the Florida Center for Analytical Electron Microscopy. The serpentine dose not chemically display brucite mixing, has minor substitution of Fe, Ni, and Cr for Mg, and minor Al substitution for Si. Bastites have higher Ni than replaced olivine. Mineral chemistry, high LOI, and X-ray diffraction suggest lizardite is the primary serpentine polymorph, with minor chrysotile also occurring. Relic Al-chromite and Cr-spinel commonly have Cr-magnetite rims. These relic cores have little SiO2 and Fe3+, suggesting the spinels are well preserved. Most spinels plot in overlap fields defined by abyssal and arc peridotite, while two samples plot entirely in arc fields. Relic olivine have Fo90 to Fo92 and plot along the mantle array. Relic pyroxene are primarily enstatite, with lesser high-Ca varieties. Relic minerals plot near fields defined by harzburgite, dunite, and lherzolite from unaltered Ingalls peridotite. The massive serpentinite likely formed by low T (< 300°C), and possibly low pressure, hydrothermal alteration of harzburgite, dunite and lherzolite. The protoliths were variably depleted mantle residues from a possible supra-subduction zone setting.

Simultaneous Ultraviolet Line and Continuum Variability Studies in Seyfert 1 Galaxies and Quasars

NASA Astrophysics Data System (ADS)

Honnappa, Vijayakumar; Prabhakar, Vedavvathi

Simultaneous Ultraviolet Line and Continuum Variability Studies in Seyfert 1 Galaxies and Quasars Vijayakumar H. Doddamani*and P. Vedavathi Department of Physics, Bangalore University, Bangalore-560056, *Corresponding author:drvkdmani@gmail.com, Abstract The line and continuum flux variability is a hallmark phenomenon of Seyfert 1 galaxies and quasars. Large amplitude luminosity variability is observed in AGNs from x-rays through radio waves over a wide-ranging timescales from minutes to years. The combinations of high luminosity and short variability time scales suggests, that the power of AGN is produced by a phenomena more efficient in terms of energy release per unit mass than ordinary stellar processes. The basic structure of AGNs thus developed based on the variability studies consists of a central super massive black hole surrounded by an accretion disk or more generally optically thick plasma radiating brightly at UV and soft X-ray wavelengths. The variability studies have been important tools of understanding the physics of the central regions of AGNs, which in general cannot be resolved with the existing or planned ground and space telescopes. Therefore, we have undertaken a study of the simultaneous ultraviolet line and continuum flux variability studies in MRK501, ESOB113-IG45 (also called as Fairall 9), MRK1506, MRK1095 V*GQCOM, PG1211+143, MRK205, PG1226+023 (also known as 3C273), PG1351+640, MRK 1383, MRK876 and QSO2251-178 as these objects have been repeatedly observed by IUE satellite over several years.. It is observed that Fairall 9, MRK 1095 and 3C273 exhibit the large amplitude variability (» 30 times) over the observed timescale, which spans several years. The remaining nine objects exhibit small amplitude (» 5 times) variability over the long time scale of observations. The highest amplitude variability is observed in Lya with a least in the MgII line. The amplitude of variability decreases in the order of Lya, CIV and Mg II, lines. These results suggest that the BLR is spatially stratified into different regions from the central compact nuclear engine. Keywords: Active galaxies, Seyfert galaxies, Quasars, Line and continuum, Variability, Supermassive black hole

Contemporaneous deposition of phyllosilicates and sulfates: Using Australian acidic saline lake deposits to describe geochemical variability on Mars

USGS Publications Warehouse

Baldridge, A.M.; Hook, S.J.; Crowley, J.K.; Marion, G.M.; Kargel, J.S.; Michalski, J.L.; Thomson, B.J.; de Souza, Filho C.R.; Bridges, N.T.; Brown, A.J.

2009-01-01

Studies of the origin of the Martian sulfate and phyllosilicate deposits have led to the hypothesis that there was a marked, global-scale change in the Mars environment from circum-neutral pH aqueous alteration in the Noachian to an acidic evaporitic system in the late Noachian to Hesperian. However, terrestrial studies suggest that two different geochemical systems need not be invoked to explain such geochemical variation.Western Australian acidic playa lakes have large pH differences separated vertically and laterally by only a few tens of meters, demonstrating how highly variable chemistries can coexist over short distances in natural environments. We suggest diverse and variable Martian aqueous environments where the coetaneous formation of phyllosilicates and sulfates at the Australian sites are analogs for regions where phyllosilicates and sulfates coexist on Mars. In these systems, Fe and alkali earth phyllosilicates represent deep facies associated with upwelling neutral to alkaline groundwater, whereas aluminous phyllosilicates and sulfates represent near-surface evaporitic facies formed from more acidic brines. Copyright 2009 by the American Geophysical Union.

Intraindividual variability of boldness is repeatable across contexts in a wild lizard.

PubMed

Highcock, Laura; Carter, Alecia J

2014-01-01

Animals do not behave in exactly the same way when repeatedly tested in the same context or situation, even once systematic variation, such as habituation, has been controlled for. This unpredictability is called intraindividual variability (IIV) and has been little studied in animals. Here we investigated how IIV in boldness (estimated by flight initiation distances) changed across two seasons--the dry, non-breeding season and the wet, breeding season--in a wild population of the Namibian rock agama, Agama planiceps. We found significant differences in IIV both between individuals and seasons, and IIV was higher in the wet season, suggesting plasticity in IIV. Further, IIV was highly repeatable (r = 0.61) between seasons and we found strong negative correlations between consistent individual differences in flight initiation distances, i.e. their boldness, and individuals' IIVs. We suggest that to understand personality in animals, researchers should generate a personality 'profile' that includes not only the relative level of a trait (i.e. its personality), but also its plasticity and variability under natural conditions.

Broadband short term X-ray variability of the quasar PDS 456

NASA Astrophysics Data System (ADS)

Matzeu, G. A.; Reeves, J. N.; Nardini, E.; Braito, V.; Costa, M. T.; Tombesi, F.; Gofford, J.

2016-05-01

We present a detailed analysis of a recent 500 ks net exposure Suzaku observation, carried out in 2013, of the nearby (z=0.184) luminous (L_bol˜1047 erg s-1) quasar PDS 456 in which the X-ray flux was unusually low. The short term X-ray spectral variability has been interpreted in terms of variable absorption and/or intrinsic continuum changes. In the former scenario, the spectral variability is due to variable covering factors of two regions of partially covering absorbers. We find that these absorbers are characterised by an outflow velocity comparable to that of the highly ionised wind, i.e. ˜ 0.25 c, at the 99.9% (3.26σ) confidence level. This suggests that the partially absorbing clouds may be the denser clumpy part of the inhomogeneous wind. Following an obscuration event we obtained a direct estimate of the size of the X-ray emitting region, to be not larger than 20 R_g in PDS 456.

Climate variations of Central Asia on orbital to millennial timescales.

PubMed

Cheng, Hai; Spötl, Christoph; Breitenbach, Sebastian F M; Sinha, Ashish; Wassenburg, Jasper A; Jochum, Klaus Peter; Scholz, Denis; Li, Xianglei; Yi, Liang; Peng, Youbing; Lv, Yanbin; Zhang, Pingzhong; Votintseva, Antonina; Loginov, Vadim; Ning, Youfeng; Kathayat, Gayatri; Edwards, R Lawrence

2016-11-11

The extent to which climate variability in Central Asia is causally linked to large-scale changes in the Asian monsoon on varying timescales remains a longstanding question. Here we present precisely dated high-resolution speleothem oxygen-carbon isotope and trace element records of Central Asia's hydroclimate variability from Tonnel'naya cave, Uzbekistan, and Kesang cave, western China. On orbital timescales, the supra-regional climate variance, inferred from our oxygen isotope records, exhibits a precessional rhythm, punctuated by millennial-scale abrupt climate events, suggesting a close coupling with the Asian monsoon. However, the local hydroclimatic variability at both cave sites, inferred from carbon isotope and trace element records, shows climate variations that are distinctly different from their supra-regional modes. Particularly, hydroclimatic changes in both Tonnel'naya and Kesang areas during the Holocene lag behind the supra-regional climate variability by several thousand years. These observations may reconcile the apparent out-of-phase hydroclimatic variability, inferred from the Holocene lake proxy records, between Westerly Central Asia and Monsoon Asia.

Climate variations of Central Asia on orbital to millennial timescales

PubMed Central

Cheng, Hai; Spötl, Christoph; Breitenbach, Sebastian F. M.; Sinha, Ashish; Wassenburg, Jasper A.; Jochum, Klaus Peter; Scholz, Denis; Li, Xianglei; Yi, Liang; Peng, Youbing; Lv, Yanbin; Zhang, Pingzhong; Votintseva, Antonina; Loginov, Vadim; Ning, Youfeng; Kathayat, Gayatri; Edwards, R. Lawrence

2016-01-01

The extent to which climate variability in Central Asia is causally linked to large-scale changes in the Asian monsoon on varying timescales remains a longstanding question. Here we present precisely dated high-resolution speleothem oxygen-carbon isotope and trace element records of Central Asia’s hydroclimate variability from Tonnel’naya cave, Uzbekistan, and Kesang cave, western China. On orbital timescales, the supra-regional climate variance, inferred from our oxygen isotope records, exhibits a precessional rhythm, punctuated by millennial-scale abrupt climate events, suggesting a close coupling with the Asian monsoon. However, the local hydroclimatic variability at both cave sites, inferred from carbon isotope and trace element records, shows climate variations that are distinctly different from their supra-regional modes. Particularly, hydroclimatic changes in both Tonnel’naya and Kesang areas during the Holocene lag behind the supra-regional climate variability by several thousand years. These observations may reconcile the apparent out-of-phase hydroclimatic variability, inferred from the Holocene lake proxy records, between Westerly Central Asia and Monsoon Asia. PMID:27833133

Proposal and Development of a High Voltage Variable Frequency Alternating Current Power System for Hybrid Electric Aircraft

NASA Technical Reports Server (NTRS)

Sadey, David J.; Taylor, Linda M.; Beach, Raymond F.

2016-01-01

The development of ultra-efficient commercial vehicles and the transition to low-carbon emission propulsion are seen as thrust paths within NASA Aeronautics. A critical enabler to these paths comes in the form of hybrid-electric propulsion systems. For megawatt-class systems, the best power system topology for these hybrid-electric propulsion systems is debatable. Current proposals within NASA and the Aero community suggest using a combination of AC and DC for power transmission. This paper proposes an alternative to the current thought model through the use of a primarily high voltage AC power generation, transmission, and distribution systems, supported by the Convergent Aeronautics Solutions (CAS) Project. This system relies heavily on the use of dual-fed induction machines, which provide high power densities, minimal power conversion, and variable speed operation. The paper presents background on the project along with the system architecture, development status and preliminary results.

Barcoding of ancient lake ostracods (crustacea) reveals cryptic speciation with extremely low distances.

PubMed

Karanovic, Ivana

2015-01-01

Ostracods are drastically reduced crustaceans, with never more than eight appendages enclosed between two valves, leaving only a limited number of morphological characters for species delineation. Conservative morphology of characters used to define genera, along with high variability of characters used to define species are creating problems in applying a morphospecies concept. A high intraspecific variability in a Lake Biwa (Japan) endemic, Physocypria biwaensis (Okubo, 1990), has been observed previously but was never studied in detail. Two sympatric forms, differing in pigmentation and size, suggest a presence of reproductive isolation. The aim of this study is to employ molecular and morphometric tools to aid in species delineation within P. biwaensis complex and reconstruct their phylogenetic relationships. A fragment of the mtCOI gene was amplified from 30 specimens, and an additional 37 specimens were studied for morphological characters. Resulting phylogenies showed that each morphologically distinct form is associated with a distinct phylogenetic group based on mtDNA. The average pairwise distance is very low (5%), indicating a recent divergence time. I speculate that there is a possibility that one of them originated in the lake, while the other probably colonized it afterwards. This seems to be supported with an apparent niche partitioning at different depths. In spite of the fact that traditionally used sexual characters are highly variable in these two species, the morphometric analysis of shell and soft part related characters clearly delineates them and suggests that such characters may be useful for future detection of seemingly cryptic ostracod species.

High-Frequency Orographically Forced Variability in a Single-Layer Model of the Martian Atmosphere

NASA Technical Reports Server (NTRS)

Keppenne, C. L.; Ingersoll, A. P.

1993-01-01

A shallow water model with realistic topography and idealized zonal wind forcing is used toinvestigate orographically forced modes in the Martian atmosphere. Locally, the model reproduceswell the climatology at the sites of Viking Lander I and II (VL1 and VL2) as inferred from theViking Lander fall and spring observations. Its variability at those sites is dominated by a 3-sol(Martian solar day) oscillation in the region of VL1 and by a 6-sol oscillation in that of VL2. Theseoscillations are forced by the zonal asymmetries of the Martian mountain field. It is suggested thatthey contribute to the observed variability by reinforcing the baroclinic oscillations with nearbyperiods identified in observational studies. The spatial variability associated with the orographicallyforced oscillations is studied by means of extended empirical orthogonal function analysis. The 3-solVL1 oscillation corresponds to a tropical, eastward-traveling, zonal-wavenumber one pattern...

Genetic variability and differentiation among populations of the Azorean endemic gymnosperm Juniperus brevifolia: baseline information for a conservation and restoration perspective.

PubMed

Silva, Luís; Elias, Rui B; Moura, Mónica; Meimberg, Harald; Dias, Eduardo

2011-12-01

The Azorean endemic gymnosperm Juniperus brevifolia (Seub.) Antoine is a top priority species for conservation in Macaronesia, based on its ecological significance in natural plant communities. To evaluate genetic variability and differentiation among J. brevifolia populations from the Azorean archipelago, we studied 15 ISSR and 15 RAPD markers in 178 individuals from 18 populations. The average number of polymorphic bands per population was 65 for both ISSR and RAPD. The majority of genetic variability was found within populations and among populations within islands, and this partitioning of variability was confirmed by AMOVA. The large majority of population pairwise F(ST) values were above 0.3 and below 0.6. The degree of population genetic differentiation in J. brevifolia was relatively high compared with other species, including Juniperus spp. The genetic differentiation among populations suggests that provenance should be considered when formulating augmentation or reintroduction strategies.

Longterm AGN variability in the BASS sample

NASA Astrophysics Data System (ADS)

Sartori, Lia; Schawinski, Kevin; Koss, Michael; Treister, Ezequiel

2018-01-01

The study of AGN variability on different timescales can provide important information about black hole accretion physics, as well as the black hole – host galaxy interaction and coevolution. Galaxies with extended AGN photoionised clouds, e.g. IC 2497 and “Hanny’s Voorwerp”, are a great laboratory to study AGN variability over 100 kyr timescales, especially in the case where the AGN is currently dropping in luminosity. Based on a large sample of optically elusive AGN in the BASS sample we suggest that AGN may ‘flicker’ on and off 100-1000 times on ~10^5 yr timescales, and that optically elusive AGN may provide information about the switching on phase. In this talk I will show how longslit and IFU observations of BASS sources, combined with high quality hard X-ray observations and black hole demographic information, can help constraining the AGN lifecycle, and ultimately what is the physics driving AGN variability.

Generic Feature Selection with Short Fat Data

PubMed Central

Clarke, B.; Chu, J.-H.

2014-01-01

SUMMARY Consider a regression problem in which there are many more explanatory variables than data points, i.e., p ≫ n. Essentially, without reducing the number of variables inference is impossible. So, we group the p explanatory variables into blocks by clustering, evaluate statistics on the blocks and then regress the response on these statistics under a penalized error criterion to obtain estimates of the regression coefficients. We examine the performance of this approach for a variety of choices of n, p, classes of statistics, clustering algorithms, penalty terms, and data types. When n is not large, the discrimination over number of statistics is weak, but computations suggest regressing on approximately [n/K] statistics where K is the number of blocks formed by a clustering algorithm. Small deviations from this are observed when the blocks of variables are of very different sizes. Larger deviations are observed when the penalty term is an Lq norm with high enough q. PMID:25346546

Synchronicity of the East Asian Summer Monsoon variability and Northern Hemisphere climate change since the last deglaciation

NASA Astrophysics Data System (ADS)

Shinozaki, T.; Uchida, M.; Minoura, K.; Kondo, M.; Rella, S. F.; Shibata, Y.

2011-06-01

Understanding of the mechanism of the East Asian Summer Monsoon (EASM) is required for the prediction of climate change in East Asia in a scenario of modern global warming. In this study, we present high-resolution climate records from peat sediments in Northeast Japan to reconstruct the EASM variability based on peat bulk cellulose δ13C since the last deglaciation. We used a 8.8 m long peat sediment core collected from the Tashiro Bog, Northeast Japan. Based on 42 14C measurements, the core bottom reaches ~15.5 ka. δ13C, accumulation rate and accumulation flux time-series correlate well to Greenland ice core δ18O variability, suggesting that the climate record in Northeast Japan is linked to global climate changes. The δ13C record at Tashiro Bog and other paleo-EASM records at Northeast and Southern China consistently demonstrate that hydrological environments were spatially different in mid-high and mid-low latitude regions over the last 15.5 kyr. During global cooling (warming) periods, mid-high and mid-low latitude regions were characterized by wet (dry) and dry (wet) environments, respectively. We suggest that these climatic patterns are related to the migration of the EASM-related rain belt during global climate changes, as a consequence of variations in intensity and location of both the Intertropical Convergence Zone (ITCZ) and the Western Pacific Subtropical High (STH). The location of the rain belt largely influences the East Asian hydrological environment. Our δ13C time-series are characterized by a 1230 yr throughout the Holocene and a 680 yr periodicity during the early Holocene. The 1230 yr periodicity is in agreement with North Atlantic ice-rafted debris (IRD) events, suggesting a teleconnection between the Northeast Japan and the North Atlantic during the Holocene. In addition, it is the first evidence that the Bond events were recorded in terrestrial sediment in Japan. On the other hand, the 680 yr periodicity between 10.0 and 8.0 kyr is consistent with a prominent 649 yr solar activity cycle, suggesting that solar activity affected EASM precipitation during the Hypsithermal, when orbital-scale solar insolation was at a maximum in the Northern Hemisphere.

Response of wheat restricted-tillering and vigorous growth traits to variables of climate change.

PubMed

Dias de Oliveira, Eduardo A; Siddique, Kadambot H M; Bramley, Helen; Stefanova, Katia; Palta, Jairo A

2015-02-01

The response of wheat to the variables of climate change includes elevated CO2, high temperature, and drought which vary according to the levels of each variable and genotype. Independently, elevated CO2, high temperature, and terminal drought affect wheat biomass and grain yield, but the interactive effects of these three variables are not well known. The aim of this study was to determine the effects of elevated CO2 when combined with high temperature and terminal drought on the high-yielding traits of restricted-tillering and vigorous growth. It was hypothesized that elevated CO2 alone, rather than combined with high temperature, ameliorates the effects of terminal drought on wheat biomass and grain yield. It was also hypothesized that wheat genotypes with more sink capacity (e.g. high-tillering capacity and leaf area) have more grain yield under combined elevated CO2, high temperature, and terminal drought. Two pairs of sister lines with contrasting tillering and vigorous growth were grown in poly-tunnels in a four-factor completely randomized split-plot design with elevated CO2 (700 µL L(-1)), high day time temperature (3 °C above ambient), and drought (induced from anthesis) in all combinations to test whether elevated CO2 ameliorates the effects of high temperature and terminal drought on biomass accumulation and grain yield. For biomass and grain yield, only main effects for climate change variables were significant. Elevated CO2 significantly increased grain yield by 24-35% in all four lines and terminal drought significantly reduced grain yield by 16-17% in all four lines, while high temperature (3 °C above the ambient) had no significant effect. A trade-off between yield components limited grain yield in lines with greater sink capacity (free-tillering lines). This response suggests that any positive response to predicted changes in climate will not overcome the limitations imposed by the trade-off in yield components. © 2014 Commonwealth of Australia. Global Change Biology © 2014 John Wiley & Sons Ltd.

Climate variability from the Florida Bay sedimentary record: Possible teleconnections to ENSO, PNA and CNP

USGS Publications Warehouse

Cronin, T. M.; Dwyer, Gary S.; Schwede, S.B.; Vann, C.D.; Dowsett, H.

2002-01-01

We analyzed decadal and interannual climate variability in South Florida since 1880 using geochemical and faunal paleosalinity indicators from isotopically dated sediment cores at Russell Bank in Florida Bay (FB). Using the relative abundance of 2 ostracode species and the Mg/Ca ratios in Loxoconcha matagordensis shells to reconstruct paleosalinity, we found evidence for cyclic oscillations in the salinity of central FB. During this time salinity fluctuated from as low as ~18 parts per thousand (ppt) to as high as ~57 ppt. Time series analyses suggest, in addition to a 5.6 yr Mg/Ca based salinity periodicity, there are 3 other modes of variability in paleosalinity indicators: 6-7, 8-9, and 13-14 yr periods which occur in all paleo-proxies. To search for factors that might cause salinity to vary in FB, we compared the Russell Bank paleosalinity record to South Florida winter rainfall, the Southern Oscillation Index (SOI), winter North Atlantic Oscillation (NAO), and the winter Pacific North American (PNA) index, and a surrogate for the PNA in the winter season, the Central North Pacific (CNP) index. SOI and PNA/CNP appear to be associated with South Florida winter precipitation. Time series analyses of SOI and winter rainfall for the period 1910-1999 suggest ~5, 6-7, 8-9 and 13-14 yr cycles. The 6-7 yr and 13-14 yr cycles correspond to those observed in the faunal and geochemical time series from Russell Bank. The main periods of the CNP index are 5-6 and 13-15 yr, which are similar to those observed in FB paleosalinity. Cross-spectral analyses show that winter rainfall and salinity are coherent at 5.6 yr with a salinity lag of ~1.6 mo. These results suggest that regional rainfall variability influences FB salinity over interannual and decadal timescales and that much of this variability may have its origin in climate variability in the Pacific Ocean/atmosphere system.

The magnetic variability of the β cep star ξ1 CMa

NASA Astrophysics Data System (ADS)

Järvinen, S. P.; Hubrig, S.; Schöller, M.; Ilyin, I.

2018-07-01

ξ1 CMa is a known magnetic star showing rotationally modulated magnetic variability with a period of 2.17937 d. However, recent work based on high-resolution spectropolarimetry suggests that the rotation period is longer than 30 years. We compare our new spectropolarimetric measurements with FORS 2 at the VLT acquired on three consecutive nights in 2017 to previous FORS 1/2 measurements of the longitudinal magnetic field strength. The new longitudinal magnetic field values are in the range from 115 to 240 G and do not support the presence of a long period.

Secure Continuous Variable Teleportation and Einstein-Podolsky-Rosen Steering

NASA Astrophysics Data System (ADS)

He, Qiongyi; Rosales-Zárate, Laura; Adesso, Gerardo; Reid, Margaret D.

2015-10-01

We investigate the resources needed for secure teleportation of coherent states. We extend continuous variable teleportation to include quantum teleamplification protocols that allow nonunity classical gains and a preamplification or postattenuation of the coherent state. We show that, for arbitrary Gaussian protocols and a significant class of Gaussian resources, two-way steering is required to achieve a teleportation fidelity beyond the no-cloning threshold. This provides an operational connection between Gaussian steerability and secure teleportation. We present practical recipes suggesting that heralded noiseless preamplification may enable high-fidelity heralded teleportation, using minimally entangled yet steerable resources.

Effects of response preference on resistance to change.

PubMed

Ringdahl, Joel E; Berg, Wendy K; Wacker, David P; Crook, Kayla; Molony, Maggie A; Vargo, Kristina K; Neurnberger, Jodi E; Zabala, Karla; Taylor, Christopher J

2018-01-01

Treatments based on differential reinforcement of alternative behavior, such as functional communication training, are widely used. Research regarding the maintenance of related treatment effects is limited. Nevin and Wacker (2013) provided a conceptual framework, rooted in behavioral momentum theory, for the study of treatment maintenance that addressed two components: (a) reemergence of problem behavior, and (b) continued expression of appropriate behavior. In the few studies on this topic, focus has been on variables impacting the reemergence of problem behavior, with fewer studies evaluating the persistence of appropriate behavior. Given the findings from applied research related to functional communication training, variables related to response topography, such as response preference, may impact this aspect of maintenance. In the current study, the impact of response preference on persistence was evaluated in the context of functional communication training for individuals who did not exhibit problem behavior (Experiment 1) and for individuals with a history of reinforcement for problem behavior (Experiment 2). High-preferred mands were more persistent than low-preferred mands. These findings suggest that response related variables, such as response preference, impact response persistence and further suggest that response related variables should be considered when developing interventions such as functional communication training. © 2018 Society for the Experimental Analysis of Behavior.

Intra- and interspecific trait variations reveal functional relationships between specific leaf area and soil niche within a subtropical forest.

PubMed

He, Dong; Chen, Yongfa; Zhao, Kangning; Cornelissen, J H C; Chu, Chengjin

2018-02-03

How functional traits vary with environmental conditions is of fundamental importance in trait-based community ecology. However, how intraspecific variability in functional traits is connected to species distribution is not well understood. This study investigated inter- and intraspecific variation of a key functional trait, i.e. specific leaf area (leaf area per unit dry mass; SLA), in relation to soil factors and tested if trait variation is more closely associated with specific environmental regimes for low-variability species than for high-variability species. In a subtropical evergreen forest plot (50 ha, southern China), 106 700 leaves from 5335 individuals of 207 woody species were intensively collected, with 30 individuals sampled for most species to ensure a sufficient sample size representative of intraspecific variability. Soil conditions for each plant were estimated by kriging from more than 1700 observational soil locations across the plot. Intra- and interspecific variation in SLA were separately related to environmental factors. Based on the species-specific variation of SLA, species were categorized into three groups: low-, intermediate- and high-intraspecific variability. Intraspecific habitat ranges and the strength of SLA-habitat relationships were compared among these three groups. Interspecific variation in SLA overrides the intraspecific variation (77 % vs. 8 %). Total soil nitrogen (TN, positively) and total organic carbon (TOC, negatively) are the most important explanatory factors for SLA variation at both intra- and interspecific levels. SLA, both within and between species, decreases with decreasing soil nitrogen availability. As predicted, species with low intraspecific variability in SLA have narrower habitat ranges with respect to soil TOC and TN and show a stronger SLA-habitat association than high-variability species. For woody plants low SLA is a phenotypic and probably adaptive response to nitrogen stress, which drives the predominance of species with ever-decreasing SLA towards less fertile habitats. Intraspecific variability in SLA is positively connected to species' niche breadth, suggesting that low-variability species may play a more deterministic role in structuring plant assemblages than high-variability species. This study highlights the importance of quantifying intraspecific trait variation to improve our understanding of species distributions across a vegetated landscape. © The Author(s) 2018. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Baseline response rates affect resistance to change.

PubMed

Kuroda, Toshikazu; Cook, James E; Lattal, Kennon A

2018-01-01

The effect of response rates on resistance to change, measured as resistance to extinction, was examined in two experiments. In Experiment 1, responding in transition from a variable-ratio schedule and its yoked-interval counterpart to extinction was compared with pigeons. Following training on a multiple variable-ratio yoked-interval schedule of reinforcement, in which response rates were higher in the former component, reinforcement was removed from both components during a single extended extinction session. Resistance to extinction in the yoked-interval component was always either greater or equal to that in the variable-ratio component. In Experiment 2, resistance to extinction was compared for two groups of rats that exhibited either high or low response rates when maintained on identical variable-interval schedules. Resistance to extinction was greater for the lower-response-rate group. These results suggest that baseline response rate can contribute to resistance to change. Such effects, however, can only be revealed when baseline response rate and reinforcement rate are disentangled (Experiments 1 and 2) from the more usual circumstance where the two covary. Furthermore, they are more cleanly revealed when the programmed contingencies controlling high and low response rates are identical, as in Experiment 2. © 2017 Society for the Experimental Analysis of Behavior.

Clinical Pharmacokinetics and Pharmacodynamics of Clopidogrel

PubMed Central

Jiang, Xi-Ling; Samant, Snehal; Lesko, Lawrence J.; Schmidt, Stephan

2017-01-01

Acute coronary syndromes (ACS) remain life-threatening disorders that are associated with high morbidity and mortality. Dual-antiplatelet therapy with aspirin and clopidogrel has shown to reduce cardiovascular events in patients with ACS. However, there is substantial inter-individual variability in response to clopidogrel treatment in addition to prolonged recovery of platelet reactivity as a result of irreversible binding to P2Y12 receptors. This high inter-individual variability in treatment response has primarily been associated with genetic polymorphisms in the genes encoding for cytochrome (CYP) 2C19 that affect clopidogrel’s pharmacokinetics. While FDA has issued a boxed warning for CYP2C19 poor metabolizers due to a potentially reduced efficacy in these patients, results from multivariate analyses suggest that additional factors, including age, sex, obesity, concurrent diseases and drug-drug interactions, may all contribute to the overall between-subject variability in treatment response. However, the extent to which each of these factors contributes to the overall variability and how they are interrelated is currently unclear. The objective of this review article is to provide a comprehensive update on the different factors that influence clopidogrel’s pharmacokinetics and pharmacodynamics and how they mechanistically contribute to inter-individual differences in response to clopidogrel treatment. PMID:25559342

A Bayesian methodological framework for accommodating interannual variability of nutrient loading with the SPARROW model

NASA Astrophysics Data System (ADS)

Wellen, Christopher; Arhonditsis, George B.; Labencki, Tanya; Boyd, Duncan

2012-10-01

Regression-type, hybrid empirical/process-based models (e.g., SPARROW, PolFlow) have assumed a prominent role in efforts to estimate the sources and transport of nutrient pollution at river basin scales. However, almost no attempts have been made to explicitly accommodate interannual nutrient loading variability in their structure, despite empirical and theoretical evidence indicating that the associated source/sink processes are quite variable at annual timescales. In this study, we present two methodological approaches to accommodate interannual variability with the Spatially Referenced Regressions on Watershed attributes (SPARROW) nonlinear regression model. The first strategy uses the SPARROW model to estimate a static baseline load and climatic variables (e.g., precipitation) to drive the interannual variability. The second approach allows the source/sink processes within the SPARROW model to vary at annual timescales using dynamic parameter estimation techniques akin to those used in dynamic linear models. Model parameterization is founded upon Bayesian inference techniques that explicitly consider calibration data and model uncertainty. Our case study is the Hamilton Harbor watershed, a mixed agricultural and urban residential area located at the western end of Lake Ontario, Canada. Our analysis suggests that dynamic parameter estimation is the more parsimonious of the two strategies tested and can offer insights into the temporal structural changes associated with watershed functioning. Consistent with empirical and theoretical work, model estimated annual in-stream attenuation rates varied inversely with annual discharge. Estimated phosphorus source areas were concentrated near the receiving water body during years of high in-stream attenuation and dispersed along the main stems of the streams during years of low attenuation, suggesting that nutrient source areas are subject to interannual variability.

The potential influence of short-term environmental variability on the composition of testate amoeba communities in Sphagnum peatlands.

PubMed

Sullivan, Maura E; Booth, Robert K

2011-07-01

Testate amoebae are a group of moisture-sensitive, shell-producing protozoa that have been widely used as indicators of changes in mean water-table depth within oligotrophic peatlands. However, short-term environmental variability (i.e., sub-annual) also probably influences community composition. The objective of this study was to assess the potential influence of short-term environmental variability on the composition of testate amoeba communities in Sphagnum-dominated peatlands. Testate amoebae and environmental conditions, including hourly measurements of relative humidity within the upper centimeter of the peatland surface, were examined throughout the 2008 growing season at 72 microsites within 11 peatlands of Pennsylvania and Wisconsin, USA. Relationships among testate amoeba communities, vegetation, depth to water table, pH, and an index of short-term environmental variability (EVI), were examined using nonmetric multidimensional scaling and correlation analysis. Results suggest that EVI influences testate amoeba communities, with some taxa more abundant under highly variable conditions (e.g., Arcella discoides, Difflugia pulex, and Hyalosphenia subflava) and others more abundant when environmental conditions at the peatland surface were relatively stable (e.g., Archerella flavum and Bullinularia indica). The magnitude of environmental variability experienced at the peatland surface appears to be primarily controlled by vegetation composition and density. In particular, sites with dense Sphagnum cover had lower EVI values than sites with loose-growing Sphagnum or vegetation dominated by vascular plants and/or non-Sphagnum bryophytes. Our results suggest that more environmental information may be inferred from testate amoebae than previously recognized. Knowledge of relationships between testate amoebae and short-term environmental variability should lead to more detailed and refined environmental inferences.

Flexibility and adaptability in binding of E. coli cytidine repressor to different operators suggests a role in differential gene regulation.

PubMed

Tretyachenko-Ladokhina, Vira; Cocco, Melanie J; Senear, Donald F

2006-09-15

Interactions between DNA-bound transcription factors CytR and CRP regulate the promoters of the Escherichia coli CytR regulon. A distinctive feature of the palindromic CytR operators is highly variable length central spacers (0-9 bp). Previously we demonstrated distinct modes of CytR binding to operators that differ in spacer length. These different modes are characterized by opposite enthalpic and entropic contributions at 25 degrees C. Of particular note were radically different negative DeltaCp values suggesting variable contribution from coupled protein folding and/or DNA structural transitions. We proposed that the CytR DNA binding-domain adopts either a more rigid or flexible DNA-bound conformation in response to the different spacer lengths. More recently, similar effects were shown to contribute to discrimination between operator and non-specific DNA binding by LacR, a CytR homolog. Here we have extended the thermodynamic analysis to the remaining natural CytR operators plus a set of synthetic operators designed to isolate spacing as the single variable. The thermodynamic results show a broad and monotonic range of effects that are primarily dependent on spacer length. The magnitude of effects suggests participation by more than the DNA-binding domain. 15N HSQC NMR and CD spectral analyses were employed to characterize the structural basis for these effects. The results indicate that while CytR forms a well-ordered structure in solution, it is highly dynamic. We propose a model in which a large ensemble of native state conformations narrows upon binding, to an extent governed by operator spacing. This in turn is expected to constrain intermolecular interactions in the CytR-CRP-DNA complex, thus generating operator-specific effects on repression and induction of transcription.

Poleward transport variability in the Northern Hemisphere during final stratospheric warmings simulated by CESM(WACCM)

NASA Astrophysics Data System (ADS)

Thiéblemont, Rémi; Matthes, Katja; Orsolini, Yvan J.; Hauchecorne, Alain; Huret, Nathalie

2016-09-01

Observational studies of Arctic stratospheric final warmings have shown that tropical/subtropical air masses can be advected to high latitudes and remain confined within a long-lived "frozen-in" anticyclone (FrIAC) for several months. It was suggested that the frequency of FrIACs may have increased since 2000 and that their interannual variability may be modulated by (i) the occurrence of major stratospheric warmings (mSSWs) in the preceding winter and (ii) the phase of the quasi-biennial oscillation (QBO). In this study, we tested these observational-based hypotheses for the first time using a chemistry climate model. Three 145 year sensitivity experiments were performed with the National Center of Atmospheric Research's Community Earth System Model (CESM): one control experiment including only natural variability, one with an extreme greenhouse gas emission scenario, and one without the QBO in the tropical stratosphere. In comparison with reanalysis, the model simulates a realistic frequency and characteristics of FrIACs, which occur under an abrupt and early winter-to-summer stratospheric circulation transition, driven by enhanced planetary wave activity. Furthermore, the model results support the suggestion that the development of FrIACs is favored by an easterly QBO in the middle stratosphere and by the absence of mSSWs during the preceding winter. The lower stratospheric persistence of background dynamical state anomalies induced by deep mSSWs leads to less favorable conditions for planetary waves to enter the high-latitude stratosphere in April, which in turn decreases the probability of FrIAC development. Our model results do not suggest that climate change conditions (RCP8.5 scenario) influence FrIAC occurrences.

Poleward Transport Variability in the Northern Hemisphere during Final Stratospheric Warmings simulated by CESM(WACCM)

NASA Astrophysics Data System (ADS)

Thiéblemont, Rémi; Matthes, Katja; Orsolini, Yvan; Hauchecorne, Alain; Huret, Nathalie

2017-04-01

Observational studies of Arctic stratospheric final warmings have shown that tropical/subtropical air masses can be advected to high latitudes and remain confined within a long-lived "frozen-in" anticyclone (FrIAC) for several months. It was suggested that the frequency of FrIACs may have increased since 2000 and that their interannual variability may be modulated by (i) the occurrence of major stratospheric warmings (mSSWs) in the preceding winter and (ii) the phase of the Quasi-Biennial Oscillation (QBO). In this study, we tested these observational-based hypotheses for the first time using a chemistry-climate model. Three 145-year sensitivity experiments were performed with the National Center of Atmospheric Research's Community Earth System Model (CESM): one control experiment including only natural variability, one with an extreme greenhouse gas emission scenario, and one without the QBO in the tropical stratosphere. In comparison with reanalysis, the model simulates a realistic frequency and characteristics of FrIACs, which occur under an abrupt and early winter-to-summer stratospheric circulation transition, driven by enhanced planetary wave activity. Furthermore, the model results support the suggestion that the development of FrIACs is favored by an easterly QBO in the middle stratosphere and by the absence of mSSWs during the preceding winter. The lower stratospheric persistence of background dynamical state anomalies induced by deep mSSWs leads to less favorable conditions for planetary waves to enter the high-latitude stratosphere in April, which in turn decreases the probability of FrIAC development. Our model results do not suggest that climate change conditions (RCP8.5 scenario) influence FrIAC occurrences.

Properties of Ca2+ sparks evoked by action potentials in mouse ventricular myocytes

PubMed Central

Bridge, John H B; Ershler, Philip R; Cannell, Mark B

1999-01-01

Calcium sparks were examined in enzymatically dissociated mouse cardiac ventricular cells using the calcium indicator fluo-3 and confocal microscopy. The properties of the mouse cardiac calcium spark are generally similar to those reported for other species.Examination of the temporal relationship between the action potential and the time course of calcium spark production showed that calcium sparks are more likely to occur during the initial repolarization phase of the action potential. The latency of their occurrence varied by less than 1·4 ms (s.d.) and this low variability may be explained by the interaction of the gating of L-type calcium channels with the changes in driving force for calcium entry during the action potential.When fixed sites within the cell are examined, calcium sparks have relatively constant amplitude but the amplitude of the sparks was variable among sites. The low variability of the amplitude of the calcium sparks suggests that more than one sarcoplasmic reticulum (SR) release channel must be involved in their genesis. Noise analysis (with the assumption of independent gating) suggests that > 18 SR calcium release channels may be involved in the generation of the calcium spark. At a fixed site, the response is close to ‘all-or-none’ behaviour which suggests that calcium sparks are indeed elementary events underlying cardiac excitation-contraction coupling.A method for selecting spark sites for signal averaging is presented which allows the time course of the spark to be examined with high temporal and spatial resolution. Using this method we show the development of the calcium spark at high signal-to-noise levels. PMID:10381593

Interrogative suggestibility: its relationship with assertiveness, social-evaluative anxiety, state anxiety and method of coping.

PubMed

Gudjonsson, G H

1988-05-01

This paper attempts to investigate empirically in 30 subjects some of the theoretical components related to individual differences that are thought by Gudjonsson & Clark (1986) to mediate interrogative suggestibility as measured by the Gudjonsson Suggestibility Scale (GSS; Gudjonsson, 1984a). The variables studied were: assertiveness, social-evaluative anxiety, state anxiety and the coping methods subjects are able to generate and implement during interrogation. Low assertiveness and high evaluative anxiety were found to correlate moderately with suggestibility, but no significant correlations emerged for 'social avoidance and distress'. State anxiety correlated significantly with suggestibility, particularly after negative feedback had been administered. Coping methods (active-cognitive/behavioural vs. avoidance) significantly predicted suggestibility scores. The findings give strong support to the theoretical model of Gudjonsson & Clark.

Validation of public health competencies and impact variables for low- and middle-income countries.

PubMed

Zwanikken, Prisca Ac; Alexander, Lucy; Huong, Nguyen Thanh; Qian, Xu; Valladares, Laura Magana; Mohamed, Nazar A; Ying, Xiao Hua; Gonzalez-Robledo, Maria Cecilia; Linh, Le Cu; Wadidi, Marwa Se Abuzaid; Tahir, Hanan; Neupane, Sunisha; Scherpbier, Albert

2014-01-20

The number of Master of Public Health (MPH) programmes in low- and middle-income countries (LMICs) is increasing, but questions have been raised regarding the relevance of their outcomes and impacts on context. Although processes for validating public health competencies have taken place in recent years in many high-income countries, validation in LMICs is needed. Furthermore, impact variables of MPH programmes in the workplace and in society have not been developed. A set of public health competencies and impact variables in the workplace and in society was designed using the competencies and learning objectives of six participating institutions offering MPH programmes in or for LMICs, and the set of competencies of the Council on Linkages Between Academia and Public Health Practice as a reference. The resulting competencies and impact variables differ from those of the Council on Linkages in scope and emphasis on social determinants of health, context specificity and intersectoral competencies. A modified Delphi method was used in this study to validate the public health competencies and impact variables; experts and MPH alumni from China, Vietnam, South Africa, Sudan, Mexico and the Netherlands reviewed them and made recommendations. The competencies and variables were validated across two Delphi rounds, first with public health experts (N = 31) from the six countries, then with MPH alumni (N = 30). After the first expert round, competencies and impact variables were refined based on the quantitative results and qualitative comments. Both rounds showed high consensus, more so for the competencies than the impact variables. The response rate was 100%. This is the first time that public health competencies have been validated in LMICs across continents. It is also the first time that impact variables of MPH programmes have been proposed and validated in LMICs across continents. The high degree of consensus between experts and alumni suggests that these public health competencies and impact variables can be used to design and evaluate MPH programmes, as well as for individual and team assessment and continuous professional development in LMICs.

Validation of public health competencies and impact variables for low- and middle-income countries

PubMed Central

2014-01-01

Background The number of Master of Public Health (MPH) programmes in low- and middle-income countries (LMICs) is increasing, but questions have been raised regarding the relevance of their outcomes and impacts on context. Although processes for validating public health competencies have taken place in recent years in many high-income countries, validation in LMICs is needed. Furthermore, impact variables of MPH programmes in the workplace and in society have not been developed. Method A set of public health competencies and impact variables in the workplace and in society was designed using the competencies and learning objectives of six participating institutions offering MPH programmes in or for LMICs, and the set of competencies of the Council on Linkages Between Academia and Public Health Practice as a reference. The resulting competencies and impact variables differ from those of the Council on Linkages in scope and emphasis on social determinants of health, context specificity and intersectoral competencies. A modified Delphi method was used in this study to validate the public health competencies and impact variables; experts and MPH alumni from China, Vietnam, South Africa, Sudan, Mexico and the Netherlands reviewed them and made recommendations. Results The competencies and variables were validated across two Delphi rounds, first with public health experts (N = 31) from the six countries, then with MPH alumni (N = 30). After the first expert round, competencies and impact variables were refined based on the quantitative results and qualitative comments. Both rounds showed high consensus, more so for the competencies than the impact variables. The response rate was 100%. Conclusion This is the first time that public health competencies have been validated in LMICs across continents. It is also the first time that impact variables of MPH programmes have been proposed and validated in LMICs across continents. The high degree of consensus between experts and alumni suggests that these public health competencies and impact variables can be used to design and evaluate MPH programmes, as well as for individual and team assessment and continuous professional development in LMICs. PMID:24438672

Power politics: National energy strategies of the nuclear newly independent states of Armenia, Lithuania and Ukraine

NASA Astrophysics Data System (ADS)

Sabonis-Chafee, Theresa Marie

The successor states of Armenia, Lithuania and Ukraine arrived at independence facing extraordinary challenges in their energy sectors. Each state was a net importer, heavily dependent on cheap energy supplies, mostly from Russia. Each state also inherited a nuclear power complex over which it had not previously exercised full control. In the time period 1991--1996, each state attempted to impose coherence on the energy sector, selecting a new course for the pieces it had inherited from a much larger, highly integrated energy structure. Each state attempted to craft national energy policies in the midst of severe supply shocks and price shocks. Each state developed institutions to govern its nuclear power sector. The states' challenges were made even greater by the fact that they had few political or economic structures necessary for energy management, and sought to create those structures at the same time. This dissertation is a systematic, non-quantitative examination of how each state's energy policies developed during the 1991--1996 time period. The theoretical premise of the analysis (drawn from Statist realism) is that systemic variables---regional climate and energy vulnerability---provide the best explanations for the resulting energy policy decisions. The dependent variable is defined as creation and reform of energy institutions. The independent variables include domestic climate, regional climate, energy vulnerability and transnational assistance. All three states adopted rhetoric and legislation declaring energy a strategic sector. The evidence suggests that two of the states, Armenia and Lithuania, which faced tense regional climates and high levels of energy vulnerability, succeeded in actually treating energy strategically, approaching energy as a matter of national security or "high politics." The third state, Ukraine, failed to do so. The evidence presented suggests that the systemic variables (regional climate and energy vulnerability) provided a more favorable environment for Ukraine, one in which the state attempted reform of the sector, but not as a concerted national security issue.

Cardiac Vagal Control and Depressive Symptoms: The Moderating Role of Sleep Quality

PubMed Central

Werner, Gabriela G.; Ford, Brett Q.; Mauss, Iris B.; Schabus, Manuel; Blechert, Jens; Wilhelm, Frank H.

2017-01-01

Lower cardiac vagal control (CVC) has been linked to greater depression. However, this link has not been consistently demonstrated, suggesting the presence of key moderators. Sleep plausibly is one such factor. Therefore, we investigated whether sleep quality moderates the link between CVC (quantified by high-frequency heart rate variability, HF-HRV) and depressive symptoms (assessed using established questionnaires) in 29 healthy women. Results revealed a significant interaction between HF-HRV and sleep quality in predicting depressive symptoms: participants with lower HF-HRV reported elevated depressive symptoms only when sleep quality was also low. In contrast, HF-HRV was not associated with depressive symptoms when sleep quality was high, suggesting a protective function of high sleep quality in the context of lower CVC. PMID:27149648

Variability and distribution of spatial evapotranspiration in semi arid Inner Mongolian grasslands from 2002 to 2011.

PubMed

Schaffrath, David; Bernhofer, Christian

2013-01-01

Grasslands in Inner Mongolia are important for livestock farming while ecosystem functioning and water consumption are dominated by evapotranspiration (ET). In this paper we studied the spatiotemporal distribution and variability of ET and its components in Inner Mongolian grasslands over a period of 10 years, from 2002 to 2011. ET was modelled pixel-wise for more than 3000 1 km(2) pixels with the physically-based hydrological model BROOK90. The model was parameterised from eddy-covariance measurements and daily input was generated from MODIS leaf area index and surface temperatures. Modelled ET was also compared with the ET provided by the MODIS MOD16 ET data. The study showed ET to be highly variable in both time and space in Inner Mongolian grasslands. The mean coefficient of variation of 8-day ET in the study area varied between 25% and 40% and was up to 75% for individual pixels indicating a high innerannual variability of ET. Generally, ET equals or exceeds P during the vegetation period, but high precipitation in 2003 clearly exceeded ET in this year indicating a recharge of soil moisture and groundwater. Despite the high interannual and innerannual variations of spatial ET, the study also showed the existence of an intrinsic long-term spatial pattern of ET distribution, which can be explained partly by altitude and longitude (R(2) = 0.49). In conclusion, the results of this research suggest the development of dynamic and productive rangeland management systems according to the inherent variability of rainfall, productivity and ET in order to restore and protect Inner Mongolian grasslands.

Spatial-frequency variability of the eddy kinetic energy in the South Atlantic Ocean

NASA Astrophysics Data System (ADS)

Cecilio, C. M.; Gherardi, D. F.; Souza, R.; Correa-Ramirez, M.

2013-05-01

In the South Atlantic Ocean (SAO) part of the inter-oceanic flow is accomplished through the issuance of anticyclonic eddies by the Agulhas Retroflection. This region, known as Agulhas Leakage (AL), is responsible by the intermittent shedding of eddies in the SAO. The propagation of these eddies into the SAO induces wave processes that allows the interaction between modes of variability of different basins, ranging from high to low frequency. Modelling studies suggests that the Indian-Atlantic inter-ocean exchange is strongly related to the structure of the wind field, in particular with the position of the maximum Southern Hemisphere westerly winds. This study aims to investigate the variations of the large-scale and regional mesoscale eddy field over the SAO using a frequency domain technique, Multiple Taper Method with Singular Value Decomposition (MTM-SVD). The MTM-SVD approach is applied to examine the individual and joint spatiotemporal variability modes of eddy kinetic energy (EKE) and winds stress. The EKE is estimated from geostrophic velocity anomalies data distributed by Aviso and winds stress from winds dataset of Cross-Calibrated Multi-Platform (CCMP) project from PO.DAAC. The impact of the AL in the SAO, was assessed first for the entire region and subsequently applied in the regions of higher mesoscale activity, which are the Brazil-Malvinas Confluence (BMC), the AL, and the Brazilian Current (BC) region. The results of local fractional variance (LFV) of EKE obtained by the MTM-SVD method show a strong significant annual variability in SAO and BC region while in BMC and in AL this frequency is weaker. In the most energetic mesoscale activity regions (BMC and AL) the pattern of variability is distinct. In the BMC region the interannual variability is dominated while in the AL region the most part of variability is associated by high frequency. The joint LFV spectrum of wind and EKE show an out-of-phase relationship between the AL region and BMC region in the interannual frequencies (3 to 5 years). The dominant frequencies can be seen in 1,5 to 3 years period band and in the intrasazonal frequencies, 0,3 to 0,5 years. The results suggests that the EKE variability patterns are different in the SAO wich might be related to the influence of eddies from AL.

Relationship of high school and college sports participation with alcohol, tobacco, and illicit drug use: A review

PubMed Central

Lisha, Nadra E.; Sussman, Steve

2011-01-01

This study provides an exhaustive review of 34 peer-reviewed quantitative data-based studies completed on high school and college sports involvement and drug use. The studies reviewed suggest that participation in sport is related to higher levels of alcohol consumption, but lower levels of both cigarette smoking and illegal drug use. Additional research is needed in this domain to further elucidate the relationship between these variables. PMID:20100638

Mn/Ca intra- and inter-test variability in the benthic foraminifer Ammonia tepida

NASA Astrophysics Data System (ADS)

Petersen, Jassin; Barras, Christine; Bézos, Antoine; La, Carole; de Nooijer, Lennart J.; Meysman, Filip J. R.; Mouret, Aurélia; Slomp, Caroline P.; Jorissen, Frans J.

2018-01-01

The adaptation of some benthic foraminiferal species to low-oxygen conditions provides the prospect of using the chemical composition of their tests as proxies for bottom water oxygenation. Manganese may be particularly suitable as such a geochemical proxy because this redox element is soluble in reduced form (Mn2+) and hence can be incorporated into benthic foraminiferal tests under low-oxygen conditions. Therefore, intra- and inter-test differences in foraminiferal Mn/Ca ratios may hold important information about short-term variability in pore water Mn2+ concentrations and sediment redox conditions. Here, we studied Mn/Ca intra- and inter-test variability in living individuals of the shallow infaunal foraminifer Ammonia tepida sampled in Lake Grevelingen (the Netherlands) in three different months of 2012. The deeper parts of this lake are characterized by seasonal hypoxia/anoxia with associated shifts in microbial activity and sediment geochemistry, leading to seasonal Mn2+ accumulation in the pore water. Earlier laboratory experiments with similar seawater Mn2+ concentrations as encountered in the pore waters of Lake Grevelingen suggest that intra-test variability due to ontogenetic trends (i.e. size-related effects) and/or other vital effects occurring during calcification in A. tepida (11-25 % relative SD, RSD) is responsible for part of the observed variability in Mn/Ca. Our present results show that the seasonally highly dynamic environmental conditions in the study area lead to a strongly increased Mn/Ca intra- and inter-test variability (average of 45 % RSD). Within single specimens, both increasing and decreasing trends in Mn/Ca ratios with size are observed. Our results suggest that the variability in successive single-chamber Mn/Ca ratios reflects the temporal variability in pore water Mn2+. Additionally, active or passive migration of the foraminifera in the surface sediment may explain part of the observed Mn/Ca variability.

High intraspecific variability in the diet of a deep-sea nematode: Stable isotope and fatty acid analyses of Deontostoma tridentum on Chatham Rise, Southwest Pacific

NASA Astrophysics Data System (ADS)

Leduc, Daniel; Brown, Julie C. S.; Bury, Sarah J.; Lörz, Anne-Nina

2015-03-01

Small deep-sea organisms may exhibit a high degree of intraspecific variability in diet due to their ability to exploit a wide range of food sources and patchiness in food availability. Trophic interactions of small deep-sea benthic organisms, however, remain poorly understood. Here we describe spatial variation in diet/trophic level of the common deep-sea nematode Deontostoma tridentum on Chatham Rise, Southwest Pacific, using carbon and nitrogen stable isotope and fatty acid analyses. We also analysed sediment organic matter (SOM) and compared the isotopic composition of D. tridentum to other benthic and suprabenthic macrofaunal taxa with a variety of feeding modes. Variability in D. tridentum δ13C and δ15N signatures was high both among sites and within a single site on the southern flank of Chatham Rise. Among-site variation in SOM δ13C signatures was not sufficient to explain variation in nematode isotopic signatures. The presence of a positive correlation between δ13C and δ15N signatures of D. tridentum (both among and within sites) could suggest that differences in trophic level is the cause behind this variation. Nitrogen isotope data suggest the presence of 1-3 trophic levels in this species, which may reflect differences in prey availability, nematode body size, or habitat (benthic versus epizoic). Nematode δ15N values exceeded those of all other taxa we investigated, including other predators, but reasons for this enrichment remain unclear. The fatty acid composition of D. tridentum did not vary substantially between sites and was characterised by relatively high levels of 18:1n9 (15-20%) and polyunsaturated fatty acids (PUFAs; 22%). Although limited inferences can be made based on fatty acid composition due to the potential impacts of non-dietary factors, high levels of PUFAs indicate that D. tridentum represents a good source of these essential nutrients to higher trophic levels. In conclusion, our results show that (1) some deep-sea organisms exhibit a high degree of intraspecific variability in diet, and (2) nematodes may be an important source of PUFAs for larger animals in deep-sea environments, where the quality of SOM is low.

Transposon Insertions, Structural Variations, and SNPs Contribute to the Evolution of the Melon Genome.

PubMed

Sanseverino, Walter; Hénaff, Elizabeth; Vives, Cristina; Pinosio, Sara; Burgos-Paz, William; Morgante, Michele; Ramos-Onsins, Sebastián E; Garcia-Mas, Jordi; Casacuberta, Josep Maria

2015-10-01

The availability of extensive databases of crop genome sequences should allow analysis of crop variability at an unprecedented scale, which should have an important impact in plant breeding. However, up to now the analysis of genetic variability at the whole-genome scale has been mainly restricted to single nucleotide polymorphisms (SNPs). This is a strong limitation as structural variation (SV) and transposon insertion polymorphisms are frequent in plant species and have had an important mutational role in crop domestication and breeding. Here, we present the first comprehensive analysis of melon genetic diversity, which includes a detailed analysis of SNPs, SV, and transposon insertion polymorphisms. The variability found among seven melon varieties representing the species diversity and including wild accessions and highly breed lines, is relatively high due in part to the marked divergence of some lineages. The diversity is distributed nonuniformly across the genome, being lower at the extremes of the chromosomes and higher in the pericentromeric regions, which is compatible with the effect of purifying selection and recombination forces over functional regions. Additionally, this variability is greatly reduced among elite varieties, probably due to selection during breeding. We have found some chromosomal regions showing a high differentiation of the elite varieties versus the rest, which could be considered as strongly selected candidate regions. Our data also suggest that transposons and SV may be at the origin of an important fraction of the variability in melon, which highlights the importance of analyzing all types of genetic variability to understand crop genome evolution. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

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.

Identification of variables influencing pharmaceutical interventions to improve medication review efficiency.

PubMed

Cornuault, Lauriane; Mouchel, Victorine; Phan Thi, Thuy-Tan; Beaussier, Hélène; Bézie, Yvonnick; Corny, Jennifer

2018-06-02

Background Clinical pharmacists' involvement has improved patients' care, by suggesting therapeutic optimizations. However, budget restrictions require a prioritization of these activities to focus resources on patients more at risk of medication errors. Objective The aim of our study was to identify variables influencing the formulation of pharmaceutical to improve medication review efficiency. Setting This study was conducted in medical wards of a 643-acute beds hospital in Paris, France. Methods All hospital medical prescriptions of all patients admitted within four medical wards (cardiology, rheumatology, neurology, vascular medicine) were analyzed. The study was conducted in each ward for 2 weeks, during 4 weeks. For each patient, variables prospectively collected were: age, gender, weight, emergency admission, number of high-alert medications and of total drugs prescribed, care unit, serum creatinine. Number of pharmaceutical interventions (PIs) and their type were reported. Main outcome measures Variables influencing the number of pharmaceutical interventions during medication review were identified using simple and multiple linear regressions. Results A total of 2328 drug prescriptions (303 patients, mean age 70.6 years-old) were analyzed. Mean number of hospital drug prescriptions was 7.9. A total of 318 PIs were formulated. Most frequent PIs were drug omission (n = 88, 27.7%), overdosing (n = 69, 21.7%), and underdosing (n = 51, 16.0%). Among variables studied, age, serum creatinine level, number of high-alert medications prescribed and total number of drugs prescribed were significantly associated with the formulation of pharmaceutical interventions (adjusted R 2  = 0.34). Conclusions This study identified variables (age, serum creatinine level, number of high-alert medication, number of prescribed drugs) that may help institutions/pharmacists target their reviews towards patients most likely to require pharmacist interventions.

Cost of resistance to trematodes in freshwater snail populations with low clonal diversity.

PubMed

Dagan, Yael; Kosman, Evsey; Ben-Ami, Frida

2017-12-13

The persistence of high genetic variability in natural populations garners considerable interest among ecologists and evolutionary biologists. One proposed hypothesis for the maintenance of high levels of genetic diversity relies on frequency-dependent selection imposed by parasites on host populations (Red Queen hypothesis). A complementary hypothesis suggests that a trade-off between fitness costs associated with tolerance to stress factors and fitness costs associated with resistance to parasites is responsible for the maintenance of host genetic diversity. The present study investigated whether host resistance to parasites is traded off with tolerance to environmental stress factors (high/low temperatures, high salinity), by comparing populations of the freshwater snail Melanoides tuberculata with low vs. high clonal diversity. Since polyclonal populations were found to be more parasitized than populations with low clonal diversity, we expected them to be tolerant to environmental stress factors. We found that clonal diversity explained most of the variation in snail survival under high temperature, thereby suggesting that tolerance to high temperatures of clonally diverse populations is higher than that of populations with low clonal diversity. Our results suggest that resistance to parasites may come at a cost of reduced tolerance to certain environmental stress factors.

Niche partitioning and biogeography of high light adapted Prochlorococcus across taxonomic ranks in the North Pacific

PubMed Central

Larkin, Alyse A; Blinebry, Sara K; Howes, Caroline; Lin, Yajuan; Loftus, Sarah E; Schmaus, Carrie A; Zinser, Erik R; Johnson, Zackary I

2016-01-01

The distribution of major clades of Prochlorococcus tracks light, temperature and other environmental variables; yet, the drivers of genomic diversity within these ecotypes and the net effect on biodiversity of the larger community are poorly understood. We examined high light (HL) adapted Prochlorococcus communities across spatial and temporal environmental gradients in the Pacific Ocean to determine the ecological drivers of population structure and diversity across taxonomic ranks. We show that the Prochlorococcus community has the highest diversity at low latitudes, but seasonality driven by temperature, day length and nutrients adds complexity. At finer taxonomic resolution, some ‘sub-ecotype' clades have unique, cohesive responses to environmental variables and distinct biogeographies, suggesting that presently defined ecotypes can be further partitioned into ecologically meaningful units. Intriguingly, biogeographies of the HL-I sub-ecotypes are driven by unique combinations of environmental traits, rather than through trait hierarchy, while the HL-II sub-ecotypes appear ecologically similar, thus demonstrating differences among these dominant HL ecotypes. Examining biodiversity across taxonomic ranks reveals high-resolution dynamics of Prochlorococcus evolution and ecology that are masked at phylogenetically coarse resolution. Spatial and seasonal trends of Prochlorococcus communities suggest that the future ocean may be comprised of different populations, with implications for ecosystem structure and function. PMID:26800235

Determinants of fast food consumption among Iranian high school students based on planned behavior theory.

PubMed

Sharifirad, Gholamreza; Yarmohammadi, Parastoo; Azadbakht, Leila; Morowatisharifabad, Mohammad Ali; Hassanzadeh, Akbar

2013-01-01

This study was conducted to identify some factors (beliefs and norms) which are related to fast food consumption among high school students in Isfahan, Iran. We used the framework of the theory planned behavior (TPB) to predict this behavior. Cross-sectional data were available from high school students (n = 521) who were recruited by cluster randomized sampling. All of the students completed a questionnaire assessing variables of standard TPB model including attitude, subjective norms, perceived behavior control (PBC), and the additional variables past behavior, actual behavior control (ABC). The TPB variables explained 25.7% of the variance in intentions with positive attitude as the strongest (β = 0.31, P < 0.001) and subjective norms as the weakest (β = 0.29, P < 0.001) determinant. Concurrently, intentions accounted for 6% of the variance for fast food consumption. Past behavior and ABC accounted for an additional amount of 20.4% of the variance in fast food consumption. Overall, the present study suggests that the TPB model is useful in predicting related beliefs and norms to the fast food consumption among adolescents. Subjective norms in TPB model and past behavior in TPB model with additional variables (past behavior and actual behavior control) were the most powerful predictors of fast food consumption. Therefore, TPB model may be a useful framework for planning intervention programs to reduce fast food consumption by students.

Design and clinical pilot testing of the model-based dynamic insulin sensitivity and secretion test (DISST).

PubMed

Lotz, Thomas F; Chase, J Geoffrey; McAuley, Kirsten A; Shaw, Geoffrey M; Docherty, Paul D; Berkeley, Juliet E; Williams, Sheila M; Hann, Christopher E; Mann, Jim I

2010-11-01

Insulin resistance is a significant risk factor in the pathogenesis of type 2 diabetes. This article presents pilot study results of the dynamic insulin sensitivity and secretion test (DISST), a high-resolution, low-intensity test to diagnose insulin sensitivity (IS) and characterize pancreatic insulin secretion in response to a (small) glucose challenge. This pilot study examines the effect of glucose and insulin dose on the DISST, and tests its repeatability. DISST tests were performed on 16 subjects randomly allocated to low (5 g glucose, 0.5 U insulin), medium (10 g glucose, 1 U insulin) and high dose (20 g glucose, 2 U insulin) protocols. Two or three tests were performed on each subject a few days apart. Average variability in IS between low and medium dose was 10.3% (p=.50) and between medium and high dose 6.0% (p=.87). Geometric mean variability between tests was 6.0% (multiplicative standard deviation (MSD) 4.9%). Geometric mean variability in first phase endogenous insulin response was 6.8% (MSD 2.2%). Results were most consistent in subjects with low IS. These findings suggest that DISST may be an easily performed dynamic test to quantify IS with high resolution, especially among those with reduced IS. © 2010 Diabetes Technology Society.

Measures of native and non-native rhythm in a quantity language.

PubMed

Stockmal, Verna; Markus, Dace; Bond, Dzintra

2005-01-01

The traditional phonetic classification of language rhythm as stress-timed or syllable-timed is attributed to Pike. Recently, two different proposals have been offered for describing the rhythmic structure of languages from acoustic-phonetic measurements. Ramus has suggested a metric based on the proportion of vocalic intervals and the variability (SD) of consonantal intervals. Grabe has proposed Pairwise Variability Indices (nPVI, rPVI) calculated from the differences in vocalic and consonantal durations between successive syllables. We have calculated both the Ramus and Grabe metrics for Latvian, traditionally considered a syllable rhythm language, and for Latvian as spoken by Russian learners. Native speakers and proficient learners were very similar whereas low-proficiency learners showed high variability on some properties. The metrics did not provide an unambiguous classification of Latvian.

Climatic variability of near-surface turbulent kinetic energy over the United States: implications for fire-weather predications

Treesearch

Warren E. Heilman; Xindi Bain

2013-01-01

Recent research suggests that high levels of ambient near-surface atmospheric turbulence are often associated with rapid and sometimes erratic wildland fire spread that may eventually lead to large burn areas. Previous research has also examined the feasibility of using near-surface atmospheric turbulent kinetic energy (TKEs) alone or in...

Regional changes and global connections: monitoring climate variability and change in the western United States

Treesearch

Henry F. Diaz

2004-01-01

Mountain ecosystems of the Western United States are complex and include cold desert biomes, such as those found in Nevada; subpolar biomes found in the upper treeline zone; and tundra ecosystems, occurring above timberline. Many studies (for example, Thompson 2000) suggest that high-elevation environments, comprising glaciers, snow, permafrost, water, and the...

Global Contexts for Learning: Exploring the Relationship between Low-Context Online Learning and High-Context Learners

ERIC Educational Resources Information Center

Westbrook, Timothy Paul

2014-01-01

Current research on culture and distance education suggests that cultural variables influence student success online. When online courses are writing-based, they may provide easy information dissemination; however, the low-context medium may restrict the learning experience and class dynamic due to the lack of nonverbal communication. Students who…

Host-plant specialization in needle-eating insects of Sweden

Treesearch

Christer Björkman; Stig Larsson

1991-01-01

It has been suggested that the enormous diversity of phytochemicals within the plant kingdom makes it impossible for one and the same insect species to exploit all plant species (Dethier 1954, Fraenkel 1959). Not surprisingly, the number and diversity of host plants utilized by different phytophagous insects are highly variable, and the specific selective pressures...

Tracking Hadean processes in modern basalts with 142-Neodymium

NASA Astrophysics Data System (ADS)

Horan, M. F.; Carlson, R. W.; Walker, R. J.; Jackson, M.; Garçon, M.; Norman, M.

2018-02-01

The short-lived 146Sm→142 Nd isotope system (t1/2 = 103 Ma) provides constraints on the timing and processes of terrestrial silicate fractionation during the early Hadean. Although some Archean terranes preserve variability in 142Nd/144Nd, no anomalies have been resolved previously in young rocks. This study provides high precision 142Nd/144Nd data on a suite of ocean island basalts from Samoa and Hawaii previously shown to have variable depletions in 182W/184W that are inversely correlated with 3He/4He ratios. Improved analytical techniques and multiple replicate analyses of Nd show a variation in μ142 Nd values between -1.3 and +2.7 in the suite, relative to the JNdi standard. Given the reproducibility of the standard (±2.9 ppm, 2 SD), two Samoan samples exhibit resolved variability in their 142Nd/144Nd ratios outside of their 95% confidence intervals, suggesting minor variability in the Samoan hotspot. One sample from Samoa has a higher μ142 Nd of +2.7, outside the 95% confidence interval (±1.0 ppm) of the average of the JNdi standard. Limited, but resolved, variation in 142Nd/144Nd within the suite suggests the preservation of early Hadean silicate differentiation in the sources of at least some basalts from Samoa. Larger variations of 182W/184W and 3He/4He ratios in the same samples suggest that metal-silicate separation and mantle outgassing left a more persistent imprint on the accessible mantle compared to 142Nd/144Nd ratios which are impacted by early silicate differentiation.

Variable broad lines and outflow in the weak blazar PBC J2333.9-2343

NASA Astrophysics Data System (ADS)

Hernández-García, L.; Vietri, G.; Panessa, F.; Piconcelli, E.; Chavushyan, V.; Jiménez-Andrade, E. F.; Bassani, L.; Bazzano, A.; Cazzoli, S.; Malizia, A.; Masetti, N.; Monaco, L.; Pović, M.; Saviane, I.; Ubertini, P.

2018-05-01

PBC J2333.9-2343 is a peculiar active nucleus with two giant radio lobes and a weak blazar-like nucleus at their center. In the present work we show new optical, UV, and X-ray data taken from the San Pedro Mártir telescope, the New Technology Telescope, NTT/EFOSC2, and the Swift/XRT satellite. The source is highly variable at all frequencies, in particular the strongest variations are found in the broad Hα component with a flux increase of 61±4 per cent between 2009 and 2016, following the X-ray flux increase of 62±6 per cent between 2010 and 2016. We also detected a broad Hβ component in 2016, making the optical classification change from type 1.9 to type 1.8 in one year. We have also detected a broad component of the [OIII]λ5007 line, which is blue-shifted and of high velocity, suggesting an origin from a highly disturbed medium, possibly an outflow. The line flux variability and broad widths are indicative of a jet that is, at least in part, responsible for the ionization of the BLR and NLR.

A Meta-analysis on Resting State High-frequency Heart Rate Variability in Bulimia Nervosa.

PubMed

Peschel, Stephanie K V; Feeling, Nicole R; Vögele, Claus; Kaess, Michael; Thayer, Julian F; Koenig, Julian

2016-09-01

Autonomic nervous system function is altered in eating disorders. We aimed to quantify differences in resting state vagal activity, indexed by high-frequency heart rate variability comparing patients with bulimia nervosa (BN) and healthy controls. A systematic search of the literature to identify studies eligible for inclusion and meta-analytical methods were applied. Meta-regression was used to identify potential covariates. Eight studies reporting measures of resting high-frequency heart rate variability in individuals with BN (n = 137) and controls (n = 190) were included. Random-effects meta-analysis revealed a sizeable main effect (Z = 2.22, p = .03; Hedge's g = 0.52, 95% CI [0.06;0.98]) indicating higher resting state vagal activity in individuals with BN. Meta-regression showed that body mass index and medication intake are significant covariates. Findings suggest higher vagal activity in BN at rest, particularly in unmedicated samples with lower body mass index. Potential mechanisms underlying these findings and implications for routine clinical care are discussed. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association.

Molecular maser flares in the high-mass star-forming region IRAS18566+0408

NASA Astrophysics Data System (ADS)

Halbe, Daniel M.

We report results of a long-termmonitoring study of 6cmformaldehyde (H 2CO), 6.035GHz hydroxyl (OH), and 6.7GHz methanol (CH3OH) masers in the young high-mass protostellar object IRAS18566+0408 (G37.55+0.20). This is the only high-mass star-forming region where correlated variability of three different maser species has been reported. The observations were conducted with the 305m Arecibo Radio Telescope, and together with data from the literature, we present H2CO flux density measurements from 2002 to 2014, CH3OH data from 2006 to 2013, and discuss OH observations obtained between 2008 and 2012. Our extended monitoring observations of the H2CO maser agree with the quasi-periodic flare phenomenon and exponential decrease in quiescent and flare flux densities proposed by Araya and collaborators in 2010. We also confirm the occurrence of 6.035GHz OH flares and a time delay with respect to the H2CO flares. An analysis between the variability behavior of different CH3OH maser components and the H2CO maser suggests that multiple variability mechanisms are responsible for CH3OH flux density changes.

The relationship between Arabian Sea upwelling and Indian Monsoon revisited in a high resolution ocean simulation

NASA Astrophysics Data System (ADS)

Yi, Xing; Hünicke, Birgit; Tim, Nele; Zorita, Eduardo

2018-01-01

Studies based on sediment records, sea-surface temperature and wind suggest that upwelling along the western coast of Arabian Sea is strongly affected by the Indian summer Monsoon. We examine this relationship directly in an eddy-resolving global ocean simulation STORM driven by atmospheric reanalysis over the last 61 years. With its very high spatial resolution (10 km), STORM allows us to identify characteristics of the upwelling system. We analyse the co-variability between upwelling and meteorological and oceanic variables from 1950 to 2010. The analysis reveals high interannual correlations between coastal upwelling and along-shore wind-stress (r = 0.73) as well as with sea-surface temperature (r = -0.83). However, the correlation between the upwelling and the Monsoon is small. We find an atmospheric circulation pattern different from the one that drives the Monsoon as the main modulator of the upwelling variability. In spite of this, the patterns of temperature anomalies that are either linked to Arabian Sea upwelling or to the Monsoon are spatially quite similar, although the physical mechanisms of these links are different. In addition, no long-term trend is detected in our modelled upwelling in the Arabian Sea.

Sensitivity and specificity of radiographic methods for predicting insertion torque of dental implants.

PubMed

Cortes, Arthur Rodriguez Gonzalez; Eimar, Hazem; Barbosa, Jorge de Sá; Costa, Claudio; Arita, Emiko Saito; Tamimi, Faleh

2015-05-01

Subjective radiographic classifications of alveolar bone have been proposed and correlated with implant insertion torque (IT). The present diagnostic study aims to identify quantitative bone features influencing IT and to use these findings to develop an objective radiographic classification for predicting IT. Demographics, panoramic radiographs (taken at the beginning of dental treatment), and cone-beam computed tomographic scans (taken for implant surgical planning) of 25 patients receiving 31 implants were analyzed. Bone samples retrieved from implant sites were assessed with dual x-ray absorptiometry, microcomputed tomography, and histology. Odds ratio, sensitivity, and specificity of all variables to predict high peak IT were assessed. A ridge cortical thickness >0.75 mm and a normal appearance of the inferior mandibular cortex were the most sensitive variables for predicting high peak IT (87.5% and 75%, respectively). A classification based on the combination of both variables presented high sensitivity (90.9%) and specificity (100%) for predicting IT. Within the limitations of this study, the results suggest that it is possible to predict IT accurately based on radiographic findings of the patient. This could be useful in the treatment plan of immediate loading cases.

Association between unemployment, income, education level, population size and air pollution in Czech cities: evidence for environmental inequality? A pilot national scale analysis.

PubMed

Branis, Martin; Linhartova, Martina

2012-09-01

We analyzed differentials in exposure to SO(2), PM(10) and NO(2) among Czech urban populations categorized according to education level, unemployment rate, population size and average annual salary. Altogether 39 cities were included in the analysis. The principal component analysis revealed two factors explaining 72.8% of the data variability. The first factor explaining 44.7% of the data variability included SO(2), PM(10), low education level and high unemployment, documenting that inhabitants with unfavorable socioeconomic status mainly reside in smaller cities with higher concentration levels of combustion-related air pollutants. The second factor explaining 28.1% of the data variability included NO(2), high salary, high education level and large population, suggesting that large cities with residents with higher socioeconomic status are exposed to higher levels of traffic-related air pollution. We conclude that, after more than a decade of free-market economy, the Czech Republic, a former Soviet satellite with a centrally planned economy, displays signs of a certain kind of environmental inequality, since environmental hazards are unevenly distributed among the Czech urban populations. Copyright © 2012 Elsevier Ltd. All rights reserved.

Estimating uncertainty in respondent-driven sampling using a tree bootstrap method.

PubMed

Baraff, Aaron J; McCormick, Tyler H; Raftery, Adrian E

2016-12-20

Respondent-driven sampling (RDS) is a network-based form of chain-referral sampling used to estimate attributes of populations that are difficult to access using standard survey tools. Although it has grown quickly in popularity since its introduction, the statistical properties of RDS estimates remain elusive. In particular, the sampling variability of these estimates has been shown to be much higher than previously acknowledged, and even methods designed to account for RDS result in misleadingly narrow confidence intervals. In this paper, we introduce a tree bootstrap method for estimating uncertainty in RDS estimates based on resampling recruitment trees. We use simulations from known social networks to show that the tree bootstrap method not only outperforms existing methods but also captures the high variability of RDS, even in extreme cases with high design effects. We also apply the method to data from injecting drug users in Ukraine. Unlike other methods, the tree bootstrap depends only on the structure of the sampled recruitment trees, not on the attributes being measured on the respondents, so correlations between attributes can be estimated as well as variability. Our results suggest that it is possible to accurately assess the high level of uncertainty inherent in RDS.

A Satellite-Based Imaging Instrumentation Concept for Hyperspectral Thermal Remote Sensing

PubMed Central

Udelhoven, Thomas; Schlerf, Martin; Segl, Karl; Mallick, Kaniska; Bossung, Christian; Rock, Gilles; Fischer, Peter; Müller, Andreas; Storch, Tobias; Eisele, Andreas; Weise, Dennis; Hupfer, Werner; Knigge, Thiemo

2017-01-01

This paper describes the concept of the hyperspectral Earth-observing thermal infrared (TIR) satellite mission HiTeSEM (High-resolution Temperature and Spectral Emissivity Mapping). The scientific goal is to measure specific key variables from the biosphere, hydrosphere, pedosphere, and geosphere related to two global problems of significant societal relevance: food security and human health. The key variables comprise land and sea surface radiation temperature and emissivity, surface moisture, thermal inertia, evapotranspiration, soil minerals and grain size components, soil organic carbon, plant physiological variables, and heat fluxes. The retrieval of this information requires a TIR imaging system with adequate spatial and spectral resolutions and with day-night following observation capability. Another challenge is the monitoring of temporally high dynamic features like energy fluxes, which require adequate revisit time. The suggested solution is a sensor pointing concept to allow high revisit times for selected target regions (1–5 days at off-nadir). At the same time, global observations in the nadir direction are guaranteed with a lower temporal repeat cycle (>1 month). To account for the demand of a high spatial resolution for complex targets, it is suggested to combine in one optic (1) a hyperspectral TIR system with ~75 bands at 7.2–12.5 µm (instrument NEDT 0.05 K–0.1 K) and a ground sampling distance (GSD) of 60 m, and (2) a panchromatic high-resolution TIR-imager with two channels (8.0–10.25 µm and 10.25–12.5 µm) and a GSD of 20 m. The identified science case requires a good correlation of the instrument orbit with Sentinel-2 (maximum delay of 1–3 days) to combine data from the visible and near infrared (VNIR), the shortwave infrared (SWIR) and TIR spectral regions and to refine parameter retrieval. PMID:28671575

Fragile and Enduring Positive Affect: Implications for Adaptive Aging.

PubMed

Ong, Anthony D; Ram, Nilam

2017-01-01

There is robust evidence linking interindividual differences in positive affect (PA) with adaptive psychological and physical health outcomes. However, recent research has suggested that intraindividual variability or fluctuations in PA states over time may also be an important predictor of individual health outcomes. Here, we report on research that focuses on PA level and various forms of PA dynamics (variability, instability, inertia, and reactivity) in relation to health. PA level refers to the average level of positive feelings. In contrast, PA dynamics refer to short-term changes in PA that unfold over time. We discuss how consideration of both PA level and PA dynamics can provide a framework for reconciling when high PA is conducive or detrimental to health. We conclude that more work on PA dynamics is needed, especially in combination with PA level, and suggest productive questions for future inquiry in this area. © 2016 S. Karger AG, Basel.

Modeling nearshore morphological evolution at seasonal scale

USGS Publications Warehouse

Walstra, D.-J.R.; Ruggiero, P.; Lesser, G.; Gelfenbaum, G.

2006-01-01

A process-based model is compared with field measurements to test and improve our ability to predict nearshore morphological change at seasonal time scales. The field experiment, along the dissipative beaches adjacent to Grays Harbor, Washington USA, successfully captured the transition between the high-energy erosive conditions of winter and the low-energy beach-building conditions typical of summer. The experiment documented shoreline progradation on the order of 20 m and as much as 175 m of onshore bar migration. Significant alongshore variability was observed in the morphological response of the sandbars over a 4 km reach of coast. A detailed sensitivity analysis suggests that the model results are more sensitive to adjusting the sediment transport associated with asymmetric oscillatory wave motions than to adjusting the transport due to mean currents. Initial results suggest that alongshore variations in the initial bathymetry are partially responsible for the observed alongshore variable morphological response during the experiment. Copyright ASCE 2006.

The importance of personality and parental styles on optimism in adolescents.

PubMed

Zanon, Cristian; Bastianello, Micheline Roat; Pacico, Juliana Cerentini; Hutz, Claudio Simon

2014-01-01

Some studies have suggested that personality factors are important to optimism development. Others have emphasized that family relations are relevant variables to optimism. This study aimed to evaluate the importance of parenting styles to optimism controlling for the variance accounted for by personality factors. Participants were 344 Brazilian high school students (44% male) with mean age of 16.2 years (SD = 1) who answered personality, optimism, responsiveness and demandingness scales. Hierarchical regression analyses were conducted having personality factors (in the first step) and maternal and paternal parenting styles, and demandingness and responsiveness (in the second step) as predictive variables and optimism as the criterion. Personality factors, especially neuroticism (β = -.34, p < .01), extraversion (β = .26, p < .01) and agreeableness (β = .16, p < .01), accounted for 34% of the optimism variance and insignificant variance was predicted exclusively by parental styles (1%). These findings suggest that personality is more important to optimism development than parental styles.

Tropical North Atlantic subsurface warming events as a fingerprint for AMOC variability during Marine Isotope Stage 3

NASA Astrophysics Data System (ADS)

Parker, Andrew O.; Schmidt, Matthew W.; Chang, Ping

2015-11-01

The role of Atlantic Meridional Overturning Circulation (AMOC) as the driver of Dansgaard-Oeschger (DO) variability that characterized Marine Isotope Stage 3 (MIS 3) has long been hypothesized. Although there is ample proxy evidence suggesting that DO events were robust features of glacial climate, there is little data supporting a link with AMOC. Recently, modeling studies and subsurface temperature reconstructions have suggested that subsurface warming across the tropical North Atlantic can be used to fingerprint a weakened AMOC during the deglacial because a reduction in the strength of the western boundary current allows warm salinity maximum water of the subtropical gyre to enter the deep tropics. To determine if AMOC variability played a role during the DO cycles of MIS 3, we present new, high-resolution Mg/Ca and δ18O records spanning 24-52 kyr from the near-surface dwelling planktonic foraminifera Globigerinoides ruber and the lower thermocline dwelling planktonic foraminifera Globorotalia truncatulinoides in Southern Caribbean core VM12-107 (11.33°N, 66.63°W, 1079 m depth). Our subsurface Mg/Ca record reveals abrupt increases in Mg/Ca ratios (the largest equal to a 4°C warming) during the interstadial-stadial transition of most DO events during this period. This change is consistent with reconstructions of subsurface warming events associated with cold events across the deglacial using the same core. Additionally, our data support the conclusion reached by a recently published study from the Florida Straits that AMOC did not undergo significant reductions during Heinrich events 2 and 3. This record presents some of the first high-resolution marine sediment derived evidence for variable AMOC during MIS 3.

Distribution and variability of total mercury in snow cover-a case study from a semi-urban site in Poznań, Poland.

PubMed

Siudek, Patrycja

2016-12-01

In the present paper, the inter-seasonal Hg variability in snow cover was examined based on multivariate statistical analysis of chemical and meteorological data. Samples of freshly fallen snow cover were collected at the semi-urban site in Poznań (central Poland), during 3-month field measurements in winter 2013. It was showed that concentrations of atmospherically deposited Hg were highly variable in snow cover, from 0.43 to 12.5 ng L -1 , with a mean value of 4.62 ng L -1 . The highest Hg concentration in snow cover coincided with local intensification of fossil fuel burning, indicating large contribution from various anthropogenic sources such as commercial and domestic heating, power generation plants, and traffic-related pollution. Moreover, the variability of Hg in collected snow samples was associated with long-range transport of pollutants, nocturnal inversion layer, low boundary layer height, and relatively low air temperature. For three snow episodes, Hg concentration in snow cover was attributed to southerly advection, suggesting significant contribution from the highly polluted region of Poland (Upper Silesia) and major European industrial hotspots. However, the peak Hg concentration was measured in samples collected during predominant N to NE advection of polluted air masses and after a relatively longer period without precipitation. Such significant contribution to the higher Hg accumulation in snow cover was associated with intensive emission from anthropogenic sources (coal combustion) and atmospheric conditions in this area. These results suggest that further measurements are needed to determine how the Hg transformation paths in snow cover change in response to longer/shorter duration of snow cover occurrence and to determine the interactions between mercury and absorbing carbonaceous aerosols in the light of climate change.

ENSO activity during the last climate cycle using IFA

NASA Astrophysics Data System (ADS)

Leduc, Guillaume; Vidal, Laurence; Thirumalai, Kaustubh

2017-04-01

The El Niño / Southern Oscillation (ENSO) is the principal mode of interannual climate variability and affects key climate parameters such as low-latitude rainfall variability. Anticipating future ENSO variability under anthropogenic forcing is vital due to its profound socioeconomic impact. Fossil corals suggest that 20th century ENSO variance is particularly high as compared to other time periods of the Holocene (Cobb et al., 2013, Science), the Last Glacial Maximum (Ford et al., 2015, Science) and the last glacial period (Tudhope et al., 2001, Science). Yet, recent climate modeling experiments suggest an increase in the frequency of both El Niño (Cai et al., 2014, Nature Climate Change) and La Niña (Cai et al., 2015, Nature Climate Change) events. We have expanded an Individual Foraminifera Analysis (IFA) dataset using the thermocline-dwelling N. dutertrei on a marine core collected in the Panama Basin (Leduc et al., 2009, Paleoceanography), that has proven to be a skillful way to reconstruct the ENSO (Thirumalai et al., 2013, Paleoceanography). Our new IFA dataset comprehensively covers the Holocene, the last deglaciation and Termination II (MIS5/6) time windows. We will also use previously published data from the Marine Isotope Stage 3 (MIS3). Our dataset confirms variable ENSO intensity during the Holocene and weaker activity during LGM than during the Holocene. As a next step, ENSO activity will be discussed with respect to the contrasting climatic background of the analysed time windows (millenial-scale variability, Terminations).

Homework compliance counts in cognitive-behavioral therapy.

PubMed

Lebeau, Richard T; Davies, Carolyn D; Culver, Najwa C; Craske, Michelle G

2013-01-01

Prior research has demonstrated that there is some association between treatment engagement and treatment outcome in behavioral therapy for anxiety disorders. However, many of these investigations have been limited by weak measurement of treatment engagement variables, failure to control for potentially important baseline variables, and failure to consider various treatment engagement variables simultaneously. The purpose of the present study is to examine the relationship between two treatment engagement variables (treatment expectancy and homework compliance) and the extent to which they predict improvement from cognitive-behavioral therapy (CBT) for anxiety disorders. 84 adults with a DSM-IV-defined principal anxiety disorder took part in up to 12 sessions of CBT or acceptance and commitment therapy. Pre- and post-treatment disorder severity was assessed using clinical severity ratings from a semi-structured diagnostic interview. Participants made ratings of treatment expectancy after the first session. Homework compliance was assessed each session by the treating clinician. Contrary to hypotheses, treatment expectancy and homework compliance were poorly correlated. Regression analyses revealed that homework compliance, but not treatment expectancy, predicted a significant portion of the variance in treatment outcome (10%). The present research suggests that although treatment expectation and homework compliance likely represent unique constructs of treatment engagement, homework compliance may be the more important treatment engagement variable for outcomes. The present research suggests that improvement of homework compliance has the potential to be a highly practical and effective way to improve clinical outcomes in CBT targeting anxiety disorders.

Weber (slope) analyses of timing variability in tapping and drawing tasks.

PubMed

Spencer, Rebecca M C; Zelaznik, Howard N

2003-12-01

Timing variability in continuous drawing tasks has not been found to be correlated with timing variability in repetitive finger tapping in recent studies (S. D. Robertson et al., 1999; H. N. Zelaznik, R. M. C. Spencer, & R. B. Ivry, 2002). Furthermore, the central component of timing variability, as measured by the slope of the timing variance versus the square of the timed interval, differed for tapping and drawing tasks. On the basis of those results, the authors posited that timing in tapping is explicit and as such uses a central representation of the interval to be timed, whereas timing in drawing tasks is implicit, that is, the temporal component is an emergent property of the trajectory produced. The authors examined that hypothesis in the present study by determining the linear relationship between timing variance and squared duration for tapping, circle-drawing, and line-drawing tasks. Participants (N = 50) performed 1 of 5 tasks: finger tapping, line drawing in the x dimension, line drawing in the y dimension, continuous circle drawing timed in the x dimension, or continuous circle drawing timed in the y dimension. The slopes differed significantly between finger tapping, line drawing, and circle drawing, suggesting separable sources of timing variability. The slopes of the 2 circle-drawing tasks did not differ from one another, nor did the slopes of the 2 line-drawing tasks differ significantly, suggesting a shared timing process within those tasks. Those results are evidence of a high degree of specificity in timing processes.

Complex Socio-Ecological Dynamics driven by extreme events in the Amazon

NASA Astrophysics Data System (ADS)

Pinho, P. F.

2015-12-01

Several years with extreme floods or droughts in the past decade have caused human suffering in remote communities of the Brazilian Amazon. Despite documented local knowledge and practices for coping with the high seasonal variability characteristic of the region's hydrology (e.g. 10m change in river levels between dry and flood seasons), and despite 'civil Defense' interventions by various levels of government, the more extreme years seem to have exceeded the coping capacity of the community. In this paper, we explore whether there is a real increase in variability, whether the community perceives that recent extreme events are outside the experience which shapes their responses to 'normal' levels of variability, and what science-based policy could contribute to greater local resilience. Hydrological analyses suggest that variability is indeed increasing, in line with expectations from future climate change. However, current measures of hydrological regimes do not predict years with social hardship very well. Interviewees in two regions are able to express their strategies for dealing with 'normal' variability very well, but also identify ways in which abnormal years exceed their ability to cope. Current Civil Defense arrangements struggle to deliver emergency assistance in a sufficiently timely and locally appropriate fashion. Combining these insights in the context of social-ecological change, we suggest how better integration of science, policy and local knowledge could improve resilience to future trends, and identify some contributions science could make into such an arrangement.

Assessing site-specific spatio-temporal variations in hydrogen and oxygen stable isotopes of human drinking water

NASA Astrophysics Data System (ADS)

Kennedy, C. D.; Bowen, G. J.; Ehleringer, J. R.

2008-12-01

Stable isotope ratios of hydrogen and oxygen (δ2H and δ18O) are environmental forensic tracers that can be used to constrain the origin and movement of animals, people, and products. The fundamental assumption underlying this method is that water resources at different geographic locations have distinct and characteristic isotopic signatures that are assimilated into organic tissues. Although much is known about regional-scale spatio-temporal variability in δ2H and δ18O of water, few studies have addressed the question of how distinct these geographic and seasonal patterns are for any given site. To address this question, a 2-year survey of δ2H and δ18O in tap water from across the contiguous U.S. and Canada was conducted. The data show that seasonal variability in δ2H and δ18O of tap water is generally low (<10 ‰ for δ2H), and those with the highest variability can be classified as: a) cities or towns in areas of high climate seasonality, or b) large cities in arid or seasonally arid regions which access and switch among multiple water sources throughout the year. The data suggest that inter-annual variation in tap water isotope ratios is typically low, with a median difference for month-month pairs during the 2 sampling years of 2.7 (δ2H). The results from this study confirm the existence of temporal variability in δ2H and δ18O of tap water, but suggest that this variability in human-managed systems is highly damped and may be amenable to classification, modeling, and prediction. In all, the data provide the foundation for incorporating temporal variation in predictive models of water and organic δ2H and δ18O, leading to more robust and statistically defensible tests of geographic origin.

18-year variability of ultraviolet radiation penetration in the mid-latitude coastal waters of the western boundary Pacific

NASA Astrophysics Data System (ADS)

Kuwahara, Victor S.; Nozaki, Sena; Nakano, Junji; Toda, Tatsuki; Kikuchi, Tomohiko; Taguchi, Satoru

2015-07-01

The 18-year time-series shows in situ ultraviolet radiation (UVR) and photosynthetically active radiation (PAR) diffuse attenuation coefficient Kd(λ) have recurrent seasonal variability of high/low attenuation during summer/winter months, respectively, dependent on variability in water column stratification and concentrations of bio-optical properties. The mid-latitude coastal survey station displayed significant seasonality of the mixed layer depth (MLD) between 12 and 82 m which modified the distribution of chlorophyll a (4.6-24.9 mg m-2) and absorption of colored dissolved organic matter [aCDOM(320 nm) 0.043-1.34 m-1]. The median Kd(320 nm) displayed significant seasonality at 0.19-0.74 m-1 (C.V. = 44.1%) and seasonal variability within the euphotic layer [Z10%(320 nm) = 7-20%]. High attenuation of UVR with relatively moderate attenuation of PAR was consistently observed during the summer months when increased concentrations of terrestrially derived CDOM coupled with a shallow MLD were present. The winter season showed the opposite of low UVR and PAR attenuation due to a relatively deeper MLD coupled with low concentrations of bio-optical properties. Although the long term Kd(λ) did not vary significantly during the time-series, analysis of the interannual variability suggests there are positive and negative phases following the Pacific Decadal Oscillation (PDO) vis-a-vis variability in bio-optical properties (p < 0.001).

Intrinsic Variability in Shell and Soft Tissue Growth of the Freshwater Mussel Lampsilis siliquoidea

PubMed Central

Larson, James H.; Eckert, Nathan L.; Bartsch, Michelle R.

2014-01-01

Freshwater mussels are ecologically and economically important members of many aquatic ecosystems, but are globally among the most imperiled taxa. Propagation techniques for mussels have been developed and used to boost declining and restore extirpated populations. Here we use a cohort of propagated mussels to estimate the intrinsic variability in size and growth rate of Lampsilis siliquoidea (a commonly propagated species). Understanding the magnitude and pattern of variation in data is critical to determining whether effects observed in nature or experimental treatments are likely to be important. The coefficient of variation (CV) of L. siliquoidea soft tissues (6.0%) was less than the CV of linear shell dimensions (25.1–66.9%). Size-weight relationships were best when mussel width (the maximum left-right dimension with both valves appressed) was used as a predictor, but 95% credible intervals on these predictions for soft tissues were ∼145 mg wide (about 50% of the mean soft tissue mass). Mussels in this study were treated identically, raised from a single cohort and yet variation in soft tissue mass at a particular size class (as determined by shell dimensions) was still high. High variability in mussel size is often acknowledged, but seldom discussed in the context of mussel conservation. High variability will influence the survival of stocked juvenile cohorts, may affect the ability to experimentally detect sublethal stressors and may lead to incongruities between the effects that mussels have on structure (via hard shells) and biogeochemical cycles (via soft tissue metabolism). Given their imperiled status and longevity, there is often reluctance to destructively sample unionid mussel soft tissues even in metabolic studies (e.g., studies of nutrient cycling). High intrinsic variability suggests that using shell dimensions (particularly shell length) as a response variable in studies of sublethal stressors or metabolic processes will make confident identifications of smaller effect sizes difficult. PMID:25411848

Intrinsic variability in shell and soft tissue growth of the freshwater mussel Lampsilis siliquoidea

USGS Publications Warehouse

Larson, James H.; Eckert, Nathan L.; Bartsch, Michelle

2014-01-01

Freshwater mussels are ecologically and economically important members of many aquatic ecosystems, but are globally among the most imperiled taxa. Propagation techniques for mussels have been developed and used to boost declining and restore extirpated populations. Here we use a cohort of propagated mussels to estimate the intrinsic variability in size and growth rate of Lampsilis siliquoidea (a commonly propagated species). Understanding the magnitude and pattern of variation in data is critical to determining whether effects observed in nature or experimental treatments are likely to be important. The coefficient of variation (CV) of L. siliquoidea soft tissues (6.0%) was less than the CV of linear shell dimensions (25.1-66.9%). Size-weight relationships were best when mussel width (the maximum left-right dimension with both valves appressed) was used as a predictor, but 95% credible intervals on these predictions for soft tissues were ~145 mg wide (about 50% of the mean soft tissue mass). Mussels in this study were treated identically, raised from a single cohort and yet variation in soft tissue mass at a particular size class (as determined by shell dimensions) was still high. High variability in mussel size is often acknowledged, but seldom discussed in the context of mussel conservation. High variability will influence the survival of stocked juvenile cohorts, may affect the ability to experimentally detect sublethal stressors and may lead to incongruities between the effects that mussels have on structure (via hard shells) and biogeochemical cycles (via soft tissue metabolism). Given their imperiled status and longevity, there is often reluctance to destructively sample unionid mussel soft tissues even in metabolic studies (e.g., studies of nutrient cycling). High intrinsic variability suggests that using shell dimensions (particularly shell length) as a response variable in studies of sublethal stressors or metabolic processes will make confident identifications of smaller effect sizes difficult.

VARIABILITY IN HOT CARBON-DOMINATED ATMOSPHERE (HOT DQ) WHITE DWARFS: RAPID ROTATION?

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

Williams, Kurtis A.; Bierwagen, Michael; Montgomery, M. H.

2016-01-20

Hot white dwarfs (WDs) with carbon-dominated atmospheres (hot DQs) are a cryptic class of WDs. In addition to their deficiency of hydrogen and helium, most of these stars are highly magnetic, and a large fraction vary in luminosity. This variability has been ascribed to nonradial pulsations, but increasing data call this explanation into question. We present studies of short-term variability in seven hot DQ WDs. Three (SDSS J1426+5752, SDSS J2200−0741, and SDSS J2348−0942) were known to be variable. Their photometric modulations are coherent over at least two years, and we find no evidence for variability at frequencies that are notmore » harmonics. We present the first time-series photometry for three additional hot DQs (SDSS J0236−0734, SDSS J1402+3818, and SDSS J1615+4543); none are observed to vary, but the signal-to-noise is low. Finally, we present high speed photometry for SDSS J0005−1002, known to exhibit a 2.1-day photometric variation; we do not observe any short-term variability. Monoperiodicity is rare among pulsating WDs, so we contemplate whether the photometric variability is due to rotation rather than pulsations; similar hypotheses have been raised by other researchers. If the variability is due to rotation, then hot DQ WDs as a class contain many rapid rotators. Given the lack of companions to these stars, the origin of any fast rotation is unclear—both massive progenitor stars and double degenerate merger remnants are possibilities. We end with suggestions of future work that would best clarify the nature of these rare, intriguing objects.« less

Decadal- to Centennial-Scale Variations in Anchovy Biomass in the Last 250 Years Inferred From Scales Preserved in Laminated Sediments off the Coast of Pisco, Peru

NASA Astrophysics Data System (ADS)

Salvatteci, R.; Field, D.; Gutierrez, D.; Baumgartner, T.; Ferreira, V.; Velazco, F.; Niquen, M.; Guevara, R.; Sifeddine, A.; Ortlieb, L.

2005-12-01

The highly productive upwelling environment off the coast of Peru sustains one of the world's largest fisheries, the Peruvian anchoveta ( Engraulis ringens), but variability on interannual to decadal timescales results in dramatic variations in catch. We quantified variations in anchovy scale abundance preserved in laminated sediments collected at 300 m depth of the Peruvian margin (near Pisco, central Peru) to infer decadal- to centennial-scale population variability prior to the development of the fishery. High-resolution subsampling of 2.5 - 8.2 mm was done following the laminated structure of the core. A chronology based on downcore excess 210Pb activities and 14C-AMS ages indicate that samples represent an estimated 1-7 years in time. Anchovy scale deposition is correlated with anchovy landings at Pisco, indicating that scale deposition can be used as a proxy of (at least) local biomass. A small, but significant, reduction in anchovy scale width (0.2 mm) after the development of the fishery suggests a small effect of the fishery on anchovy size distributions. While decadal-scale variability in anchovy scale deposition is persistent throughout the record, a dramatic increase in scale flux occurred around 1860 A.D. and persists for approximately a century. Our results indicate that centennial-scale variability composes a large portion of the variability. However, decadal-scale variability associated with the Pacific Decadal Oscillation is not correlated with the inferred biomass variability prior to the development of the fishery. Shifts in the distribution of the population may account for an additional component of the variability in scale deposition.

The impact of inter-annual rainfall variability on African savannas changes with mean rainfall.

PubMed

Synodinos, Alexis D; Tietjen, Britta; Lohmann, Dirk; Jeltsch, Florian

2018-01-21

Savannas are mixed tree-grass ecosystems whose dynamics are predominantly regulated by resource competition and the temporal variability in climatic and environmental factors such as rainfall and fire. Hence, increasing inter-annual rainfall variability due to climate change could have a significant impact on savannas. To investigate this, we used an ecohydrological model of stochastic differential equations and simulated African savanna dynamics along a gradient of mean annual rainfall (520-780 mm/year) for a range of inter-annual rainfall variabilities. Our simulations produced alternative states of grassland and savanna across the mean rainfall gradient. Increasing inter-annual variability had a negative effect on the savanna state under dry conditions (520 mm/year), and a positive effect under moister conditions (580-780 mm/year). The former resulted from the net negative effect of dry and wet extremes on trees. In semi-arid conditions (520 mm/year), dry extremes caused a loss of tree cover, which could not be recovered during wet extremes because of strong resource competition and the increased frequency of fires. At high mean rainfall (780 mm/year), increased variability enhanced savanna resilience. Here, resources were no longer limiting and the slow tree dynamics buffered against variability by maintaining a stable population during 'dry' extremes, providing the basis for growth during wet extremes. Simultaneously, high rainfall years had a weak marginal benefit on grass cover due to density-regulation and grazing. Our results suggest that the effects of the slow tree and fast grass dynamics on tree-grass interactions will become a major determinant of the savanna vegetation composition with increasing rainfall variability. Copyright © 2017 Elsevier Ltd. All rights reserved.

Are persistent early onset child conduct problems predicted by the trajectories and initial levels of discipline practices?

PubMed

Lorber, Michael F; Slep, Amy M Smith

2015-08-01

In the present investigation we focused on 2 broad sets of questions: Do parental overreactivity, laxness, and corporal punishment show evidence of normative change in early to middle childhood? Are persistently elevated child conduct problems (CPs) associated with deviations from normative changes in, as well as high initial levels of, discipline practices? Four hundred fifty-three couples with 3- to 7-year-old children were recruited via random digit dialing and studied at 3 annual assessments. Parents completed questionnaire measures of all study constructs. Normative declines were found in maternal corporal punishment and laxness. Maternal overreactivity showed a normative increase. For fathers, only corporal punishment showed evidence of a normative decline. The declines in mothers' corporal punishment and laxness, and in fathers' corporal punishment, exhibited little variability. In contrast, the trajectories of maternal overreactivity were significantly variable. High-increasing CPs were more common than low-stable CPs in families with greater increases in maternal overreactivity. High-increasing CPs were also more common in families with greater initial maternal overreactivity and corporal punishment. Yet in no case did discipline practices significantly distinguish children on high-increasing versus high-decreasing CPs trajectories. In tests of alternative models, child effects were found for all parenting variables, suggesting reciprocal causation. The findings are discussed relative to etiological models of CPs and implications for preventive intervention. (c) 2015 APA, all rights reserved).

Potential Impact of North Atlantic Climate Variability on Ocean Biogeochemical Processes

NASA Astrophysics Data System (ADS)

Liu, Y.; Muhling, B.; Lee, S. K.; Muller-Karger, F. E.; Enfield, D. B.; Lamkin, J. T.; Roffer, M. A.

2016-02-01

Previous studies have shown that upper ocean circulations largely determine primary production in the euphotic layers, here the global ocean model with biogeochemistry (GFDL's Modular Ocean Model with TOPAZ biogeochemistry) forced with the ERA-Interim is used to simulate the natural variability of biogeochemical processes in global ocean during 1979-present. Preliminary results show that the surface chlorophyll is overall underestimated in MOM-TOPAZ, but its spatial pattern is fairly realistic. Relatively high chlorophyll variability is shown in the subpolar North Atlantic, northeastern tropical Atlantic, and equatorial Atlantic. Further analysis suggests that the chlorophyll variability in the North Atlantic Ocean is affected by long-term climate variability. For the subpolar North Atlantic region, the chlorophyll variability is light-limited and is significantly correlated with North Atlantic Oscillation. A dipole pattern of chlorophyll variability is found between the northeastern tropical Atlantic and equatorial Atlantic. For the northeastern North Atlantic, the chlorophyll variability is significantly correlated with Atlantic Meridional Mode (AMM) and Atlantic Multidecadal Oscillation (AMO). During the negative phase of AMM and AMO, the increased trade wind in the northeast North Atlantic can lead to increased upwelling of nutrients. In the equatorial Atlantic region, the chlorophyll variability is largely link to Atlantic-Niño and associated equatorial upwelling of nutrients. The potential impact of climate variability on the distribution of pelagic fishes (i.e. yellowfin tuna) are discussed.

Climate variability controls on unsaturated water and chemical movement, High Plains aquifer, USA

USGS Publications Warehouse

Gurdak, J.J.; Hanson, R.T.; McMahon, P.B.; Bruce, B.W.; McCray, J.E.; Thyne, G.D.; Reedy, R.C.

2007-01-01

Responses in the vadose zone and groundwater to interannual, interdecadal, and multidecadal climate variability have important implications for groundwater resource sustainability, yet they are poorly documented and not well understood in most aquifers of the USA. This investigation systematically examines the role of interannual to multidecadal climate variability on groundwater levels, deep infiltration (3-23 m) events, and downward displacement (>1 m) of chloride and nitrate reservoirs in thick (15-50 m) vadose zones across the regionally extensive High Plains aquifer. Such vadose zone responses are unexpected across much of the aquifer given a priori that unsaturated total-potential profiles indicate upward water movement from the water table toward the root zone, mean annual potential evapotranspiration exceeds mean annual precipitation, and millennia-scale evapoconcentration results in substantial vadose zone chloride and nitrate reservoirs. Using singular spectrum analysis (SSA) to reconstruct precipitation and groundwater level time-series components, variability was identified in all time series as partially coincident with known climate cycles, such as the Pacific Decadal Oscillation (PDO) (10-25 yr) and the El Nin??o/Southern Oscillation (ENSO) (2-6 yr). Using these lag-correlated hydrologic time series, a new method is demonstrated to estimate climate-varying unsaturated water flux. The results suggest the importance of interannual to interdecadal climate variability on water-flux estimation in thick vadose zones and provide better understanding of the climate-induced transients responsible for the observed deep infiltration and chemical-mobilization events. Based on these results, we discuss implications for climate-related sustainability of the High Plains aquifer. ?? Soil Science Society of America.

Understanding Human-Coyote Encounters in Urban Ecosystems Using Citizen Science Data: What Do Socioeconomics Tell Us?

NASA Astrophysics Data System (ADS)

Wine, Stuart; Gagné, Sara A.; Meentemeyer, Ross K.

2015-01-01

The coyote ( Canis latrans) has dramatically expanded its range to include the cities and suburbs of the western US and those of the Eastern Seaboard. Highly adaptable, this newcomer's success causes conflicts with residents, necessitating research to understand the distribution of coyotes in urban landscapes. Citizen science can be a powerful approach toward this aim. However, to date, the few studies that have used publicly reported coyote sighting data have lacked an in-depth consideration of human socioeconomic variables, which we suggest are an important source of overlooked variation in data that describe the simultaneous occurrence of coyotes and humans. We explored the relative importance of socioeconomic variables compared to those describing coyote habitat in predicting human-coyote encounters in highly-urbanized Mecklenburg County, North Carolina, USA using 707 public reports of coyote sightings, high-resolution land cover, US Census data, and an autologistic multi-model inference approach. Three of the four socioeconomic variables which we hypothesized would have an important influence on encounter probability, namely building density, household income, and occupation, had effects at least as large as or larger than coyote habitat variables. Our results indicate that the consideration of readily available socioeconomic variables in the analysis of citizen science data improves the prediction of species distributions by providing insight into the effects of important factors for which data are often lacking, such as resource availability for coyotes on private property and observer experience. Managers should take advantage of citizen scientists in human-dominated landscapes to monitor coyotes in order to understand their interactions with humans.

Integrating models that depend on variable data

NASA Astrophysics Data System (ADS)

Banks, A. T.; Hill, M. C.

2016-12-01

Models of human-Earth systems are often developed with the goal of predicting the behavior of one or more dependent variables from multiple independent variables, processes, and parameters. Often dependent variable values range over many orders of magnitude, which complicates evaluation of the fit of the dependent variable values to observations. Many metrics and optimization methods have been proposed to address dependent variable variability, with little consensus being achieved. In this work, we evaluate two such methods: log transformation (based on the dependent variable being log-normally distributed with a constant variance) and error-based weighting (based on a multi-normal distribution with variances that tend to increase as the dependent variable value increases). Error-based weighting has the advantage of encouraging model users to carefully consider data errors, such as measurement and epistemic errors, while log-transformations can be a black box for typical users. Placing the log-transformation into the statistical perspective of error-based weighting has not formerly been considered, to the best of our knowledge. To make the evaluation as clear and reproducible as possible, we use multiple linear regression (MLR). Simulations are conducted with MatLab. The example represents stream transport of nitrogen with up to eight independent variables. The single dependent variable in our example has values that range over 4 orders of magnitude. Results are applicable to any problem for which individual or multiple data types produce a large range of dependent variable values. For this problem, the log transformation produced good model fit, while some formulations of error-based weighting worked poorly. Results support previous suggestions fthat error-based weighting derived from a constant coefficient of variation overemphasizes low values and degrades model fit to high values. Applying larger weights to the high values is inconsistent with the log-transformation. Greater consistency is obtained by imposing smaller (by up to a factor of 1/35) weights on the smaller dependent-variable values. From an error-based perspective, the small weights are consistent with large standard deviations. This work considers the consequences of these two common ways of addressing variable data.

Variable climatic conditions dominate recent phytoplankton dynamics in Chesapeake Bay

NASA Astrophysics Data System (ADS)

Harding, Lawrence W., Jr.; Mallonee, Michael E.; Perry, Elgin S.; Miller, W. David; Adolf, Jason E.; Gallegos, Charles L.; Paerl, Hans W.

2016-03-01

Variable climatic conditions strongly influence phytoplankton dynamics in estuaries globally. Our study area is Chesapeake Bay, a highly productive ecosystem providing natural resources, transportation, and recreation for nearly 16 million people inhabiting a 165,000-km2 watershed. Since World War II, nutrient over-enrichment has led to multiple ecosystem impairments caused by increased phytoplankton biomass as chlorophyll-a (chl-a). Doubled nitrogen (N) loadings from 1945-1980 led to increased chl-a, reduced water clarity, and low dissolved oxygen (DO), while decreased N loadings from 1981-2012 suggest modest improvement. The recent 30+ years are characterized by high inter-annual variability of chl-a, coinciding with irregular dry and wet periods, complicating the detection of long-term trends. Here, we synthesize time-series data for historical and recent N loadings (TN, NO2 + NO3), chl-a, floral composition, and net primary productivity (NPP) to distinguish secular changes caused by nutrient over-enrichment from spatio-temporal variability imposed by climatic conditions. Wet years showed higher chl-a, higher diatom abundance, and increased NPP, while dry years showed lower chl-a, lower diatom abundance, and decreased NPP. Our findings support a conceptual model wherein variable climatic conditions dominate recent phytoplankton dynamics against a backdrop of nutrient over-enrichment, emphasizing the need to separate these effects to gauge progress toward improving water quality in estuaries.

Variable climatic conditions dominate recent phytoplankton dynamics in Chesapeake Bay.

PubMed

Harding, Lawrence W; Mallonee, Michael E; Perry, Elgin S; Miller, W David; Adolf, Jason E; Gallegos, Charles L; Paerl, Hans W

2016-03-30

Variable climatic conditions strongly influence phytoplankton dynamics in estuaries globally. Our study area is Chesapeake Bay, a highly productive ecosystem providing natural resources, transportation, and recreation for nearly 16 million people inhabiting a 165,000-km(2) watershed. Since World War II, nutrient over-enrichment has led to multiple ecosystem impairments caused by increased phytoplankton biomass as chlorophyll-a (chl-a). Doubled nitrogen (N) loadings from 1945-1980 led to increased chl-a, reduced water clarity, and low dissolved oxygen (DO), while decreased N loadings from 1981-2012 suggest modest improvement. The recent 30+ years are characterized by high inter-annual variability of chl-a, coinciding with irregular dry and wet periods, complicating the detection of long-term trends. Here, we synthesize time-series data for historical and recent N loadings (TN, NO2 + NO3), chl-a, floral composition, and net primary productivity (NPP) to distinguish secular changes caused by nutrient over-enrichment from spatio-temporal variability imposed by climatic conditions. Wet years showed higher chl-a, higher diatom abundance, and increased NPP, while dry years showed lower chl-a, lower diatom abundance, and decreased NPP. Our findings support a conceptual model wherein variable climatic conditions dominate recent phytoplankton dynamics against a backdrop of nutrient over-enrichment, emphasizing the need to separate these effects to gauge progress toward improving water quality in estuaries.

Variable climatic conditions dominate recent phytoplankton dynamics in Chesapeake Bay

PubMed Central

Harding, Jr., Lawrence W.; Mallonee, Michael E.; Perry, Elgin S.; Miller, W. David; Adolf, Jason E.; Gallegos, Charles L.; Paerl, Hans W.

2016-01-01

Variable climatic conditions strongly influence phytoplankton dynamics in estuaries globally. Our study area is Chesapeake Bay, a highly productive ecosystem providing natural resources, transportation, and recreation for nearly 16 million people inhabiting a 165,000-km2 watershed. Since World War II, nutrient over-enrichment has led to multiple ecosystem impairments caused by increased phytoplankton biomass as chlorophyll-a (chl-a). Doubled nitrogen (N) loadings from 1945–1980 led to increased chl-a, reduced water clarity, and low dissolved oxygen (DO), while decreased N loadings from 1981–2012 suggest modest improvement. The recent 30+ years are characterized by high inter-annual variability of chl-a, coinciding with irregular dry and wet periods, complicating the detection of long-term trends. Here, we synthesize time-series data for historical and recent N loadings (TN, NO2 + NO3), chl-a, floral composition, and net primary productivity (NPP) to distinguish secular changes caused by nutrient over-enrichment from spatio-temporal variability imposed by climatic conditions. Wet years showed higher chl-a, higher diatom abundance, and increased NPP, while dry years showed lower chl-a, lower diatom abundance, and decreased NPP. Our findings support a conceptual model wherein variable climatic conditions dominate recent phytoplankton dynamics against a backdrop of nutrient over-enrichment, emphasizing the need to separate these effects to gauge progress toward improving water quality in estuaries. PMID:27026279

Inter-decadal change in potential predictability of the East Asian summer monsoon

NASA Astrophysics Data System (ADS)

Li, Jiao; Ding, Ruiqiang; Wu, Zhiwei; Zhong, Quanjia; Li, Baosheng; Li, Jianping

2018-05-01

The significant inter-decadal change in potential predictability of the East Asian summer monsoon (EASM) has been investigated using the signal-to-noise ratio method. The relatively low potential predictability appears from the early 1950s through the late 1970s and during the early 2000s, whereas the potential predictability is relatively high from the early 1980s through the late 1990s. The inter-decadal change in potential predictability of the EASM can be attributed mainly to variations in the external signal of the EASM. The latter is mostly caused by the El Niño-Southern Oscillation (ENSO) inter-decadal variability. As a major external signal of the EASM, the ENSO inter-decadal variability experiences phase transitions from negative to positive phases in the late 1970s, and to negative phases in the late 1990s. Additionally, ENSO is generally strong (weak) during a positive (negative) phase of the ENSO inter-decadal variability. The strong ENSO is expected to have a greater influence on the EASM, and vice versa. As a result, the potential predictability of the EASM tends to be high (low) during a positive (negative) phase of the ENSO inter-decadal variability. Furthermore, a suite of Pacific Pacemaker experiments suggests that the ENSO inter-decadal variability may be a key pacemaker of the inter-decadal change in potential predictability of the EASM.

Identifying Variability in Mental Models Within and Between Disciplines Caring for the Cardiac Surgical Patient.

PubMed

Brown, Evans K H; Harder, Kathleen A; Apostolidou, Ioanna; Wahr, Joyce A; Shook, Douglas C; Farivar, R Saeid; Perry, Tjorvi E; Konia, Mojca R

2017-07-01

The cardiac operating room is a complex environment requiring efficient and effective communication between multiple disciplines. The objectives of this study were to identify and rank critical time points during the perioperative care of cardiac surgical patients, and to assess variability in responses, as a correlate of a shared mental model, regarding the importance of these time points between and within disciplines. Using Delphi technique methodology, panelists from 3 institutions were tasked with developing a list of critical time points, which were subsequently assigned to pause point (PP) categories. Panelists then rated these PPs on a 100-point visual analog scale. Descriptive statistics were expressed as percentages, medians, and interquartile ranges (IQRs). We defined low response variability between panelists as an IQR ≤ 20, moderate response variability as an IQR > 20 and ≤ 40, and high response variability as an IQR > 40. Panelists identified a total of 12 PPs. The PPs identified by the highest number of panelists were (1) before surgical incision, (2) before aortic cannulation, (3) before cardiopulmonary bypass (CPB) initiation, (4) before CPB separation, and (5) at time of transfer of care from operating room (OR) to intensive care unit (ICU) staff. There was low variability among panelists' ratings of the PP "before surgical incision," moderate response variability for the PPs "before separation from CPB," "before transfer from OR table to bed," and "at time of transfer of care from OR to ICU staff," and high response variability for the remaining 8 PPs. In addition, the perceived importance of each of these PPs varies between disciplines and between institutions. Cardiac surgical providers recognize distinct critical time points during cardiac surgery. However, there is a high degree of variability within and between disciplines as to the importance of these times, suggesting an absence of a shared mental model among disciplines caring for cardiac surgical patients during the perioperative period. A lack of a shared mental model could be one of the factors contributing to preventable errors in cardiac operating rooms.

Including long-range dependence in integrate-and-fire models of the high interspike-interval variability of cortical neurons.

PubMed

Jackson, B Scott

2004-10-01

Many different types of integrate-and-fire models have been designed in order to explain how it is possible for a cortical neuron to integrate over many independent inputs while still producing highly variable spike trains. Within this context, the variability of spike trains has been almost exclusively measured using the coefficient of variation of interspike intervals. However, another important statistical property that has been found in cortical spike trains and is closely associated with their high firing variability is long-range dependence. We investigate the conditions, if any, under which such models produce output spike trains with both interspike-interval variability and long-range dependence similar to those that have previously been measured from actual cortical neurons. We first show analytically that a large class of high-variability integrate-and-fire models is incapable of producing such outputs based on the fact that their output spike trains are always mathematically equivalent to renewal processes. This class of models subsumes a majority of previously published models, including those that use excitation-inhibition balance, correlated inputs, partial reset, or nonlinear leakage to produce outputs with high variability. Next, we study integrate-and-fire models that have (nonPoissonian) renewal point process inputs instead of the Poisson point process inputs used in the preceding class of models. The confluence of our analytical and simulation results implies that the renewal-input model is capable of producing high variability and long-range dependence comparable to that seen in spike trains recorded from cortical neurons, but only if the interspike intervals of the inputs have infinite variance, a physiologically unrealistic condition. Finally, we suggest a new integrate-and-fire model that does not suffer any of the previously mentioned shortcomings. By analyzing simulation results for this model, we show that it is capable of producing output spike trains with interspike-interval variability and long-range dependence that match empirical data from cortical spike trains. This model is similar to the other models in this study, except that its inputs are fractional-gaussian-noise-driven Poisson processes rather than renewal point processes. In addition to this model's success in producing realistic output spike trains, its inputs have long-range dependence similar to that found in most subcortical neurons in sensory pathways, including the inputs to cortex. Analysis of output spike trains from simulations of this model also shows that a tight balance between the amounts of excitation and inhibition at the inputs to cortical neurons is not necessary for high interspike-interval variability at their outputs. Furthermore, in our analysis of this model, we show that the superposition of many fractional-gaussian-noise-driven Poisson processes does not approximate a Poisson process, which challenges the common assumption that the total effect of a large number of inputs on a neuron is well represented by a Poisson process.

An Open Trial of a Smartphone-Assisted, Adjunctive Intervention to Improve Treatment Adherence in Bipolar Disorder

PubMed Central

Wenze, Susan J.; Armey, Michael F.; Weinstock, Lauren M.; Gaudiano, Brandon A.; Miller, Ivan W.

2016-01-01

We evaluated the feasibility and acceptability of a novel, 12 week, adjunctive, smartphone-assisted intervention to improve treatment adherence in bipolar disorder (BD). Eight participants completed 4 in-person individual therapy sessions over the course of a month, followed by 60 days of twice-daily ecological momentary intervention (EMI) sessions, with a fifth in-person session after 30 days and a sixth in-person session after 60 days. Perceived credibility of the intervention and expectancy for change were adequate at baseline, and satisfaction on completion of the intervention was very high. Participants demonstrated good adherence to the intervention overall, including excellent adherence to the in-person component and fair adherence to the smartphone-facilitated component. Qualitative feedback revealed very high satisfaction with the in-person sessions and suggested a broad range of ways in which the EMI sessions were helpful. Participants also provided suggestions for improving the intervention, which primarily related to the structure and administration of the EMI (smartphone-administered) sessions. Although this study was not designed to evaluate treatment efficacy, most key outcome variables changed in the expected directions from pre- to post-treatment, and several variables changed significantly over the course of the in-person sessions or during the EMI phase. These findings add to the small but growing body of literature suggesting that EMIs are feasible and acceptable for use in populations with BD. PMID:27824786

Separating heat stress from moisture stress: analyzing yield response to high temperature in irrigated maize

NASA Astrophysics Data System (ADS)

Carter, Elizabeth K.; Melkonian, Jeff; Riha, Susan J.; Shaw, Stephen B.

2016-09-01

Several recent studies have indicated that high air temperatures are limiting maize (Zea mays L.) yields in the US Corn Belt and project significant yield losses with expected increases in growing season temperatures. Further work has suggested that high air temperatures are indicative of high evaporative demand, and that decreases in maize yields which correlate to high temperatures and vapor pressure deficits (VPD) likely reflect underlying soil moisture limitations. It remains unclear whether direct high temperature impacts on yields, independent of moisture stress, can be observed under current temperature regimes. Given that projected high temperature and moisture may not co-vary the same way as they have historically, quantitative analyzes of direct temperature impacts are critical for accurate yield projections and targeted mitigation strategies under shifting temperature regimes. To evaluate yield response to above optimum temperatures independent of soil moisture stress, we analyzed climate impacts on irrigated maize yields obtained from the National Corn Growers Association (NCGA) corn yield contests for Nebraska, Kansas and Missouri. In irrigated maize, we found no evidence of a direct negative impact on yield by daytime air temperature, calculated canopy temperature, or VPD when analyzed seasonally. Solar radiation was the primary yield-limiting climate variable. Our analyses suggested that elevated night temperature impacted yield by increasing rates of phenological development. High temperatures during grain-fill significantly interacted with yields, but this effect was often beneficial and included evidence of acquired thermo-tolerance. Furthermore, genetics and management—information uniquely available in the NCGA contest data—explained more yield variability than climate, and significantly modified crop response to climate. Thermo-acclimation, improved genetics and changes to management practices have the potential to partially or completely offset temperature-related yield losses in irrigated maize.

Does high diurnal variability in a reef flat from Ofu, American Samoa confer resistance to ocean acidification?

NASA Astrophysics Data System (ADS)

Koweek, D.; Samuel, L.; Mucciarone, D. A.; Woodson, C. B.; Monismith, S. G.; Dunbar, R. B.

2012-12-01

Forecasts for coral reefs under various ocean acidification scenarios are becoming increasingly complex due to significant inter-site variability in biogeochemistry, ecology, and physical oceanography. The reef flats of Ofu, American Samoa are a potential end-member of this vulnerability spectrum due to extremely high diurnal variability in their biogeochemistry. Here we present coupled biogeochemical and physical oceanographic measurements from a shallow reef flat on Ofu in November 2011. We observed diurnal temperature ranges of up to 7°C, along with diurnal pH and dissolved oxygen ranges of 0.6 units, and 160 percent of saturation, respectively. Carbon system measurements were less extreme. Alkalinity varied between 2240-2360 μmol/kg and total dissolved inorganic carbon (TDIC) ranged between 1850-2100 μmol/kg during the diurnal cycle. These observations suggest diurnal ranges of ~240ppm CO2 and 1.5 units of ΩAr. The larger diurnal range in TDIC relative to alkalinity suggests a reef environment dominated by photosynthesis. From these observations, we explore the balance between the dominant biogeochemical processes of production and calcification on the reef flat in more detail, along with its implication for conferring resistance to ocean acidification. We use calcification rate estimates to provide insight to patterns of day and night growth and/or dissolution on the reef. Finally, we present evidence of tidal modulation of the biogeochemical signals and discuss the role of localized physical circulation in helping to determine a reef's vulnerability to ocean acidification.

Coastal Land Air Sea Interaction: "the" beach towers

NASA Astrophysics Data System (ADS)

MacMahan, J. H.; Koscinski, J. S.; Ortiz-Suslow, D. G.; Haus, B. K.; Thornton, E. B.

2016-12-01

As part of the Coastal Land Air Sea Interaction (CLASI) experiment, an alongshore array of 6-m high towers instrumented with ultrasonic 3D anemometers and temperature-relative humidity sensors were deployed at five sandy beaches near the high-tide line in Monterey Bay, CA, in May-June 2016. A cross-shore array of towers was also deployed from within the active surfzone to the toe of the dune at one beach. In addition, waves and ocean temperature were obtained along the 10m isobath for each beach. The dissipative surfzone was O(80m) wide. The wave energy varies among the beaches owing to sheltering and refraction by the Monterey Canyon and headlands. The tides are semi-diurnal mixed, meso-tidal with a maximum tidal range of 2m. This results in a variable beach width from the tower to the tidal line. Footprint analysis for estimating the source region for the turbulent momentum fluxes, suggests that the observations represent three scenarios described as primarily ocean, mixed beach and ocean, and primarily beach. The direct-estimate of the atmospheric stability by the sonic anemometer suggest that all of the beaches are mostly unstable except for a few occurrences in the evening during low wind conditions. The onshore neutral drag coefficient (Cd) estimated at 10m heights is 3-5 times larger than open ocean estimates. Minimal variability was found in Cd based on the footprint analysis. Beach-specific spatial variability in Cd was found related to atmospheric stability and wave energy.

Effects of coal mining, forestry, and road construction on southern Appalachian stream invertebrates and habitats.

PubMed

Gangloff, Michael M; Perkins, Michael; Blum, Peter W; Walker, Craig

2015-03-01

Coal has been extracted via surface and sub-surface mining for decades throughout the Appalachian Mountains. New interest in ridge-top mining has raised concerns about possible waterway impacts. We examined effects of forestry, mining, and road construction-based disturbance on physico-chemistry and macroinvertebrate communities in east-central Tennessee headwater streams. Although 11 of 30 sites failed Tennessee's biocriteria scoring system, invertebrate richness was moderately high and we did not find significant differences in any water chemistry or habitat parameters between sites with passing and failing scores. However, conductivity and dissolved solid concentrations appeared elevated in the majority of study streams. Principal components (PCs) analysis indicated that six PCs accounted for ~77 % of among-site habitat variability. One PC associated with dissolved oxygen and specific conductance explained the second highest proportion of among-site variability after catchment area. Specific conductance was not correlated with catchment area but was strongly correlated with mining activity. Composition and success of multivariate models using habitat PCs to predict macroinvertebrate metrics was highly variable. PC scores associated with water chemistry and substrate composition were most frequently included in significant models. These results suggest that impacts of historical and current coal mining remain a source of water quality and macroinvertebrate community impairment in this region, but effects are subtle. Our results suggest that surface mining may have chronic and system-wide effects on habitat conditions and invertebrate communities in Cumberland Plateau streams.

Risk stratification using stress echocardiography: incremental prognostic value over historic, clinical, and stress electrocardiographic variables across a wide spectrum of bayesian pretest probabilities for coronary artery disease.

PubMed

Bangalore, Sripal; Gopinath, Devi; Yao, Siu-Sun; Chaudhry, Farooq A

2007-03-01

We sought to evaluate the risk stratification ability and incremental prognostic value of stress echocardiography over historic, clinical, and stress electrocardiographic (ECG) variables, over a wide spectrum of bayesian pretest probabilities of coronary artery disease (CAD). Stress echocardiography is an established technique for the diagnosis of CAD. However, data on incremental prognostic value of stress echocardiography over historic, clinical, and stress ECG variables in patients with known or suggested CAD is limited. We evaluated 3259 patients (60 +/- 13 years, 48% men) undergoing stress echocardiography. Patients were grouped into low (<15%), intermediate (15-85%), and high (>85%) pretest CAD likelihood subgroups using standard software. The historical, clinical, stress ECG, and stress echocardiographic variables were recorded for the entire cohort. Follow-up (2.7 +/- 1.1 years) for confirmed myocardial infarction (n = 66) and cardiac death (n = 105) was obtained. For the entire cohort, an ischemic stress echocardiography study confers a 5.0 times higher cardiac event rate than the normal stress echocardiography group (4.0% vs 0.8%/y, P < .0001). Furthermore, Cox proportional hazard regression model showed incremental prognostic value of stress echocardiography variables over historic, clinical, and stress ECG variables across all pretest probability subgroups (global chi2 increased from 5.1 to 8.5 to 20.1 in the low pretest group, P = .44 and P = .01; from 20.9 to 28.2 to 116 in the intermediate pretest group, P = .47 and P < .0001; and from 17.5 to 36.6 to 61.4 in the high pretest group, P < .0001 for both groups). A normal stress echocardiography portends a benign prognosis (<1% event rate/y) in all pretest probability subgroups and even in patients with high pretest probability and yields incremental prognostic value over historic, clinical, and stress ECG variables across all pretest probability subgroups. The best incremental value is, however, in the intermediate pretest probability subgroup.

A comparison of the sensitivity, specificity, and molecular weight accuracy of three different commercially available Hyaluronan ELISA-like assays.

PubMed

Haserodt, Sarah; Aytekin, Metin; Dweik, Raed A

2011-02-01

Hyaluronan (HA) is a glycosaminoglycan found in the extracellular matrix and ranges from several thousand to millions of daltons in size. HA has importance in various pathological conditions and is known to be elevated in several diseases. Three commonly used, commercially available HA enzyme-linked immunosorbent assay (ELISA)-like assays (from Corgenix, Echelon and R&D) were compared on the basis of accuracy, sample variability and ability to measure a range of HA sizes. The Corgenix HA ELISA-like assay displayed the lowest intra-assay variability [coefficient of variation (CV) = 11.7 ± 3.6%], followed by R&D (CV = 12.3 ± 4.6%) and Echelon (CV = 18.9 ± 9.2%). Interassay variability was also lowest for the Corgenix assay (CV = 6.0%), intermediate for the Echelon assay (9.5%) and highest for the R&D assay (CV = 34.1%). The high interassay variability seen for the R&D assay may have been due to the effect of dilution, since the dilution-independent interassay variability was 15.5%. The concentration of the standard HA was overestimated by the Echelon assay by 85% and underestimated by the R&D and Corgenix assays by 34 and 32%, respectively. The Echelon HA ELISA-like assay was the most effective at measuring all sizes of HA tested (2 MDa and 132, 66 and 6.4 kDa), whereas the Corgenix and R&D assays were unable to detect 6.4 kDa HA. These findings suggest that the Echelon HA ELISA-like assay is better suited for size-sensitive HA measurements but has a relatively high variability. The Corgenix and R&D HA ELISA-like assays have low variability and high accuracy but are not suitable for detecting low-molecular-weight HA.

Longitudinal analysis reveals characteristically high proportions of bacterial vaginosis-associated bacteria and temporal variability of vaginal microbiota in northern pig-tailed macaques (Macaca leonina).

PubMed

Zhu, Lin; Lei, Ai-Hua; Zheng, Hong-Yi; Lyu, Long-Bao; Zhang, Zhi-Gang; Zheng, Yong-Tang

2015-09-18

The complex and dynamic vaginal microbial ecosystem is critical to both health and disease of the host. Studies focusing on how vaginal microbiota influences HIV-1 infection may face limitations in selecting proper animal models. Given that northern pig-tailed macaques (Macaca leonina) are susceptible to HIV-1 infection, they may be an optimal animal model for elucidating the mechanisms by which vaginal microbiota contributes to resistance and susceptibility to HIV-1 infection. However, little is known about the composition and temporal variability of vaginal microbiota of the northern pig-tailed macaque. Here, we present a comprehensive catalog of the composition and temporal dynamics of vaginal microbiota of two healthy northern pig-tailed macaques over 19 weeks using 454-pyrosequencing of 16S rRNA genes. We found remarkably high proportions of a diverse array of anaerobic bacteria associated with bacterial vaginosis. Atopobium and Sneathia were dominant genera, and interestingly, we demonstrated the presence of Lactobacillus-dominated vaginal microbiota. Moreover, longitudinal analysis demonstrated that the temporal dynamics of the vaginal microbiota were considerably individualized. Finally, network analysis revealed that vaginal pH may influence the temporal dynamics of the vaginal microbiota, suggesting that inter-subject variability of vaginal bacterial communities could be mirrored in inter-subject variation in correlation profiles of species with each other and with vaginal pH over time. Our results suggest that the northern pig-tailed macaque could be an ideal animal model for prospective investigation of the mechanisms by which vaginal microbiota influence susceptibility and resistance to HIV-1 infection in the context of highly polymicrobial and Lactobacillus-dominated states.

Articular cartilage degeneration classification by means of high-frequency ultrasound.

PubMed

Männicke, N; Schöne, M; Oelze, M; Raum, K

2014-10-01

To date only single ultrasound parameters were regarded in statistical analyses to characterize osteoarthritic changes in articular cartilage and the potential benefit of using parameter combinations for characterization remains unclear. Therefore, the aim of this work was to utilize feature selection and classification of a Mankin subset score (i.e., cartilage surface and cell sub-scores) using ultrasound-based parameter pairs and investigate both classification accuracy and the sensitivity towards different degeneration stages. 40 punch biopsies of human cartilage were previously scanned ex vivo with a 40-MHz transducer. Ultrasound-based surface parameters, as well as backscatter and envelope statistics parameters were available. Logistic regression was performed with each unique US parameter pair as predictor and different degeneration stages as response variables. The best ultrasound-based parameter pair for each Mankin subset score value was assessed by highest classification accuracy and utilized in receiver operating characteristics (ROC) analysis. The classifications discriminating between early degenerations yielded area under the ROC curve (AUC) values of 0.94-0.99 (mean ± SD: 0.97 ± 0.03). In contrast, classifications among higher Mankin subset scores resulted in lower AUC values: 0.75-0.91 (mean ± SD: 0.84 ± 0.08). Variable sensitivities of the different ultrasound features were observed with respect to different degeneration stages. Our results strongly suggest that combinations of high-frequency ultrasound-based parameters exhibit potential to characterize different, particularly very early, degeneration stages of hyaline cartilage. Variable sensitivities towards different degeneration stages suggest that a concurrent estimation of multiple ultrasound-based parameters is diagnostically valuable. In-vivo application of the present findings is conceivable in both minimally invasive arthroscopic ultrasound and high-frequency transcutaneous ultrasound. Copyright © 2014 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

Temperament as a Predictor of Symptomotology and Adaptive Functioning in Adolescents with High-Functioning Autism

PubMed Central

Schwartz, Caley B.; Henderson, Heather A.; Inge, Anne P.; Zahka, Nicole E.; Coman, Drew C.; Kojkowski, Nicole M.; Hileman, Camilla M.; Mundy, Peter C.

2009-01-01

Variation in temperament is characteristic of all people but is rarely studied as a predictor of individual differences among individuals with autism. Relative to a matched comparison sample, adolescents with High-Functioning Autism (HFA) reported lower levels of Surgency and higher levels of Negative Affect. Variability in temperament predicted symptomotology, social skills, and social-emotional outcomes differently for individuals with HFA than for the comparison sample. This study is unique in that temperament was measured by self-report, while all outcome measures were reported by parents. The broader implications of this study suggest that by identifying individual variability in constructs, such as temperament, that may influence adaptive functioning, interventions may be developed to target these constructs and increase the likelihood that individuals with HFA will achieve more adaptive life outcomes. PMID:19165586

Measuring cardiac waste: the premier cardiac waste measures.

PubMed

Lowe, Timothy J; Partovian, Chohreh; Kroch, Eugene; Martin, John; Bankowitz, Richard

2014-01-01

The authors developed 8 measures of waste associated with cardiac procedures to assist hospitals in comparing their performance with peer facilities. Measure selection was based on review of the research literature, clinical guidelines, and consultation with key stakeholders. Development and validation used the data from 261 hospitals in a split-sample design. Measures were risk adjusted using Premier's CareScience methodologies or mean peer value based on Medicare Severity Diagnosis-Related Group assignment. High variability was found in resource utilization across facilities. Validation of the measures using item-to-total correlations (range = 0.27-0.78), Cronbach α (.88), and Spearman rank correlation (0.92) showed high reliability and discriminatory power. Because of the level of variability observed among hospitals, this study suggests that there is opportunity for facilities to design successful waste reduction programs targeting cardiac-device procedures.

Controls of picophytoplankton abundance and composition in a highly dynamic marine system, the Northern Alboran Sea (Western Mediterranean)

NASA Astrophysics Data System (ADS)

Amorim, Ana L.; León, Pablo; Mercado, Jesús M.; Cortés, Dolores; Gómez, Francisco; Putzeys, Sebastien; Salles, Soluna; Yebra, Lidia

2016-06-01

The Alboran Sea is a highly dynamic basin which exhibits a high spatio-temporal variability of hydrographic structures (e.g. fronts, gyres, coastal upwellings). This work compares the abundance and composition of picophytoplankton observed across the northern Alboran Sea among eleven cruises between 2008 and 2012 using flow cytometry. We evaluate the seasonal and longitudinal variability of picophytoplankton on the basis of the circulation regimes at a regional scale and explore the presence of cyanobacteria ecotypes in the basin. The maximal abundances obtained for Prochlorococcus, Synechococcus and picoeukaryotes (12.7 × 104, 13.9 × 104 and 8.6 × 104 cells mL- 1 respectively) were consistent with those reported for other adjacent marine areas. Seasonal changes in the abundance of the three picophytoplankton groups were highly significant although they did not match the patterns described for other coastal waters. Higher abundances of Prochlorococcus were obtained in autumn-winter while Synechococcus and picoeukaryotes exhibited a different seasonal abundance pattern depending on the sector (e.g. Synechococcus showed higher abundance in summer in the west sector and during winter in the eastern study area). Additionally, conspicuous longitudinal gradients were observed for Prochlorococcus and Synechococcus, with Prochlorococcus decreasing from west to east and Synechococcus following the opposite pattern. The analysis of environmental variables (i.e. temperature, salinity and inorganic nutrients) and cell abundances indicates that Prochlorococcus preferred high salinity and nitrate to phosphate ratio. On the contrary, temperature did not seem to play a role in Prochlorococcus distribution as it was numerically important during the whole seasonal cycle. Variability in Synechococcus abundance could not be explained by changes in any environmental variable suggesting that different ecotypes were sampled during the surveys. In particular, our data would indicate the presence of at least two ecotypes of Synechococcus: a summer ecotype widely distributed in the whole Alboran Sea and a winter ecotype adapted to lower temperature and higher nutrient concentration whose growth is favoured in the eastern sector.

Intermitted Occurrence of Millennial-scale Variability of East Asian Summer Monsoon before 1.45 Ma based on the High-resolution Br Record of the Japan Sea Sediments

NASA Astrophysics Data System (ADS)

Tada, R.; Seki, A.; Ikeda, M.; Irino, T.; Ikehara, K.; Karasuda, A.; Sugisaki, S.; Sagawa, T.; Itaki, T.; Kubota, Y.; Murayama, M.; Lu, S.; Murray, R. W.; Alvarez Zarikian, C. A.

2017-12-01

It is well-known that Dansgaard-Oeschger Cycles (DOC) and East Asian Summer Monsoon (EASM) are closely linked during the last glacial period, and that Atlantic Meridional Ocean Circulation (AMOC) played a key role to amplify and propagate the DOC signal. Climatic model studies also suggested that on and off of AMOC caused simultaneous north-south shifts of westerly jets (WJ) in both hemispheres and ITCZ. Since WJ over East Asia bounds the northern limit of EASM front, it is likely that N-S shifts of WJ caused millennial-scale variability of EASM precipitation distribution. This linkage can be traced back to ca. 0.4 Ma based on comparison of synthetic Greenland temperature record of Barker et al. (2011) with d18O record of Chinese speleothems, and back to 0.8 Ma based on comparison of synthetic Greenland temperature record with Br profile of the hemipelagic sediments of the Japan Sea (reflecting marine organic carbon content and considered as a proxy of EASM) retrieved from Site U1424 during IODP Exp. 346. Br profile of the Japan Sea sediments also implies that millennial-scale variability of EASM was persistent since ca. 1.45 Ma ago, which was probably linked with AMOC variability. However, presence/absence of millennial-scale variability of EASM and possibility of its linkage with AMOC variability are not known for the period before 1.45 Ma. Here we extend our Br record of Site U1424 back to ca. 3 Ma and demonstrate that there was intermitted occurrence of millennial-scale EASM variability since ca. 2.5 Ma when LR04 glacial d18O value first exceeded ca. 4 permil. This may suggest the presence of threshold of ice volume to cause millennial-scale variability of AMOC and EASM.

A test of Hirschi's social bonding theory: a comparison of male and female delinquency.

PubMed

Ozbay, Ozden; Ozcan, Yusuf Ziya

2008-04-01

In this study, Hirschi's social bonding theory is employed to identify what aspects of the theory can explain male and female delinquency and whether social bonding variables can equally explain male and female delinquency (generalizability problem) in a developing society, Turkey. The data include a two-stage-stratified cluster sample of 1,710 high school students from the central districts of Ankara, the capital of Turkey. The findings suggest that social bonding variables play a more important role for male students than for female students. Furthermore, they indicate that components of the social bonding theory can equally explain both male and female delinquent acts.

Does tidal capture produce cataclysmic variables?

NASA Technical Reports Server (NTRS)

Bailyn, Charles D.; Grindlay, Jonathan E.; Garcia, Michael R.

1990-01-01

It is shown that earlier estimates of the number of cataclysmic variables (CVs) to be expected from tidal capture in globular clusters may have been considerably too high, since many such binaries will result in unstable mass transfer, and thus not become CVs after all. In particular, CVs with white dwarf masses less than or obout 1.0 solar mass will be supressed. Such unstable mass transfer events may produce some of the cluster mass loss required to stabilize the cluster core. The smaller number of stable CVs predicted may suggest a reconsideration of the nature of some of the low-luminosity cluster X-ray sources.

Bacterial influence on alkenones in live microalgae.

PubMed

Segev, Einat; Castañeda, Isla S; Sikes, Elisabeth L; Vlamakis, Hera; Kolter, Roberto

2016-02-01

The microalga Emiliania huxleyi produces alkenone lipids that are important proxies for estimating past sea surface temperatures. Field calibrations of this proxy are robust but highly variable results are obtained in culture. Here, we present results suggesting that algal-bacterial interactions may be responsible for some of this variability. Co-cultures of E. huxleyi and the bacterium Phaeobacter inhibens resulted in a 2.5-fold decrease in algal alkenone-containing lipid bodies. In addition levels of unsaturated alkenones increase in co-cultures. These changes result in an increase in the reconstructed growth temperature of up to 2°C relative to axenic algal cultures. © 2015 Phycological Society of America.

Bacterial Influence on Alkenones in Live Microalgae1

PubMed Central

Segev, Einat; Castañeda, Isla S.; Sikes, Elisabeth L.; Vlamakis, Hera; Kolter, Roberto

2015-01-01

The microalga Emiliania huxleyi produces alkenone lipids which are important proxies for estimating past sea surface temperatures. Field calibrations of this proxy are robust but highly variable results are obtained in culture. Here we present results suggesting that algal-bacterial interactions may be responsible for some of this variability. Co-cultures of E. huxleyi and the bacterium Phaeobacter inhibens resulted in a 2.5-fold decrease in algal alkenone-containing lipid bodies. In addition levels of unsaturated alkenones increase in co-cultures. These changes result in an increase in the reconstructed growth temperature of up to 2°C relative to axenic algal cultures. PMID:26987094

Autonomous bed-sediment imaging-systems for revealing temporal variability of grain size

USGS Publications Warehouse

Buscombe, Daniel; Rubin, David M.; Lacy, Jessica R.; Storlazzi, Curt D.; Hatcher, Gerald; Chezar, Henry; Wyland, Robert; Sherwood, Christopher R.

2014-01-01

We describe a remotely operated video microscope system, designed to provide high-resolution images of seabed sediments. Two versions were developed, which differ in how they raise the camera from the seabed. The first used hydraulics and the second used the energy associated with wave orbital motion. Images were analyzed using automated frequency-domain methods, which following a rigorous partially supervised quality control procedure, yielded estimates to within 20% of the true size as determined by on-screen manual measurements of grains. Long-term grain-size variability at a sandy inner shelf site offshore of Santa Cruz, California, USA, was investigated using the hydraulic system. Eighteen months of high frequency (min to h), high-resolution (μm) images were collected, and grain size distributions compiled. The data constitutes the longest known high-frequency record of seabed-grain size at this sample frequency, at any location. Short-term grain-size variability of sand in an energetic surf zone at Praa Sands, Cornwall, UK was investigated using the ‘wave-powered’ system. The data are the first high-frequency record of grain size at a single location of a highly mobile and evolving bed in a natural surf zone. Using this technology, it is now possible to measure bed-sediment-grain size at a time-scale comparable with flow conditions. Results suggest models of sediment transport at sandy, wave-dominated, nearshore locations should allow for substantial changes in grain-size distribution over time-scales as short as a few hours.

Social determinants of denture/bridge use: Japan gerontological evaluation study project cross-sectional study in older Japanese.

PubMed

Yamamoto, Tatsuo; Kondo, Katsunori; Aida, Jun; Suzuki, Kayo; Misawa, Jimpei; Nakade, Miyo; Fuchida, Shinya; Hirata, Yukio

2014-06-03

Studies suggest that using a denture/bridge may prevent disability in older people. However, not all older people with few remaining teeth use a denture/bridge. This cross-sectional study aimed to examine the social determinants which promote denture/bridge use among older Japanese. A total of 54,388 (25,630 males and 28,758 females) community-dwelling individuals aged 65 or over, living independently, able to perform daily activities, and with 19 or fewer teeth. The dependent variable was denture/bridge use. Socio-demographics, number of teeth, present illness, social participation, social support, and social networks were used as individual-level independent variables. Data for social capital were aggregated and used as local district (n = 561 for males, n = 562 for females) -level independent variables. Number of dentists working in hospitals/clinics per population and population density were used as municipality (n = 28) -level independent variables. Three-level multilevel Poisson regression analysis was performed for each sex. High equivalent income, low number of teeth, present illness, and living in a municipality with high population density were significantly associated with denture/bridge use in both sexes in the fully adjusted models (p < 0.05). Denture/bridge use was significantly associated with high educational attainment in males and participating in social groups in females in the fully adjusted model (p < 0.05). No significant associations were observed between denture/bridge use and social capital. Denture/bridge use was significantly associated with high economic status and present illness in both sexes, high educational attainment in males, and participation in social groups in females among community-dwelling older Japanese after adjusting for possible confounders.

High-Intensity Interval Exercises' Acute Impact on Heart Rate Variability: Comparison Between Whole-Body and Cycle Ergometer Protocols.

PubMed

Schaun, Gustavo Z; Del Vecchio, Fabrício B

2018-01-01

Schaun, GZ and Del Vecchio, FB. High-intensity interval exercises' acute impact on heart rate variability: comparison between whole-body and cycle ergometer protocols. J Strength Cond Res 32(1): 223-229, 2018-Study aimed to compare the effects of 2 high-intensity interval training (HIIT) protocols on heart rate variability. Twelve young adult males (23.3 ± 3.9 years, 177.8 ± 7.4 cm, 76.9 ± 12.9 kg) volunteered to participate. In a randomized cross-over design, subjects performed 2 HIIT protocols, 1 on a cycle ergometer (Tabata protocol [TBT]; eight 20-second bouts at 170% Pmax interspersed by 10-second rest) and another with whole-body calisthenic exercises (McRae protocol; eight 20-second all-out intervals interspersed by 10-second rest). Heart rate variability outcomes in the time, frequency, and nonlinear domains were assessed on 3 moments: (a) presession; (b) immediately postsession; and (c) 24 hours postsession. Results revealed that RRmean, Ln rMSSD, Ln high frequency (HF), and Ln low frequency (LF) were significantly reduced immediately postsession (p ≤ 0.001) and returned to baseline 24 h after both protocols. In addition, LF/HF ratio was reduced 24 h postsession (p ≤ 0.01) and SD2 was significantly lower immediately postsession only in TBT. Our main finding was that responses from heart rate autonomic control were similar in both protocols, despite different modes of exercise performed. Specifically, exercises resulted in a high parasympathetic inhibition immediately after session with subsequent recovery within 1 day. These results suggest that subjects were already recovered the day after and can help coaches to better program training sessions with such protocols.

I Paid for It, So I Deserve It! Examining Psycho-Educational Variables and Student Consumerist Attitudes to Higher Education

ERIC Educational Resources Information Center

Marshall, Jason E.; Fayombo, Grace; Marshall, Rasheda

2015-01-01

There is a growing concern among educators and university administrators that the high cost of tuition fees has encouraged tertiary level students to adopt a "consumerist view" of tertiary education, where education is seen as a service-for-payment. Anecdotal evidence suggests that this belief may cause lecturers to compromise the…

Differential Perceptions of the Seriousness of Male Violence Against Female Intimate Partners Among Jews and Arabs in Israel

ERIC Educational Resources Information Center

Herzog, Sergio

2004-01-01

Crime seriousness studies have consistently shown wide consensus regarding the high perceived seriousness of violent offenses. However, socio-cultural models suggest wide variability between social groups with regard to the seriousness of certain types of violent crime. This is particularly true in the case of male violence against female intimate…

The glycoprotein TRP36 of Ehrlichia sp. UFMG-EV and related cattle pathogen Ehrlichia sp. UFMT-BV evolved from a highly variable clade of E. canis under adaptive diversifying selection.

PubMed

Cabezas-Cruz, Alejandro; Valdés, James J; de la Fuente, José

2014-12-10

A new species of Ehrlichia, phylogenetically distant from E. ruminantium, was found in 2010 infecting cattle in Canada. In 2012 and 2013, we reported the in vitro propagation, molecular and ultrastructural characterization of Ehrlichia sp. UFMG-EV (E. mineirensis), a new species of Ehrlichia isolated from the haemolymph of Brazilian Rhipicephalus (Boophilus) microplus ticks. A new organism, named Ehrlichia sp. UFMT-BV, closely related to Ehrlichia sp. UFMG-EV, was recently described in Brazil and after experimental infection it was shown to be pathogenic for cattle. This new emerging clade of cattle Ehrlichia pathogens is closely related to E. canis. The major immunogenic Tandem Repeat Protein (TRP36; also known as gp36) is extensively used to characterize the genetic diversity of E. canis. Homologs of TRP36 were found in both Ehrlichia sp. UFMG-EV and Ehrlichia sp. UFMT-BV. Herein, we characterized the evolution of this new Ehrlichia clade using TRP36 sequences. Our working hypothesis is that Ehrlichia sp. UFMG-EV and related microorganisms evolved from a highly variable E. canis clade. In support of our hypothesis we found that Ehrlichia sp. UFMG-EV and Ehrlichia sp. UFMT-BV TRP36 evolved from a highly divergent and variable clade within E. canis and this clade evolved under episodic diversifying selection with a high proportion of sites under positive selection. Our results suggest that Ehrlichia sp. UFMG-EV and Ehrlichia sp. UFMT-BV evolved from a variable clade within E. canis.

Being Moved by Unfamiliar Sad Music Is Associated with High Empathy

PubMed Central

Eerola, Tuomas; Vuoskoski, Jonna K.; Kautiainen, Hannu

2016-01-01

The paradox of enjoying listening to music that evokes sadness is yet to be fully understood. Unlike prior studies that have explored potential explanations related to lyrics, memories, and mood regulation, we investigated the types of emotions induced by unfamiliar, instrumental sad music, and whether these responses are consistently associated with certain individual difference variables. One hundred and two participants were drawn from a representative sample to minimize self-selection bias. The results suggest that the emotional responses induced by unfamiliar sad music could be characterized in terms of three underlying factors: Relaxing sadness, Moving sadness, and Nervous sadness. Relaxing sadness was characterized by felt and perceived peacefulness and positive valence. Moving sadness captured an intense experience that involved feelings of sadness and being moved. Nervous sadness was associated with felt anxiety, perceived scariness and negative valence. These interpretations were supported by indirect measures of felt emotion. Experiences of Moving sadness were strongly associated with high trait empathy and emotional contagion, but not with other previously suggested traits such as absorption or nostalgia-proneness. Relaxing sadness and Nervous sadness were not significantly predicted by any of the individual difference variables. The findings are interpreted within a theoretical framework of embodied emotions. PMID:27695424

Baleen whale infrasonic sounds: Natural variability and function

NASA Astrophysics Data System (ADS)

Clark, Christopher W.

2004-05-01

Blue and fin whales (Balaenoptera musculus and B. physalus) produce very intense, long, patterned sequences of infrasonic sounds. The acoustic characteristics of these sounds suggest strong selection for signals optimized for very long-range propagation in the deep ocean as first hypothesized by Payne and Webb in 1971. This hypothesis has been partially validated by very long-range detections using hydrophone arrays in deep water. Humpback songs recorded in deep water contain units in the 20-l00 Hz range, and these relatively simple song components are detectable out to many hundreds of miles. The mid-winter peak in the occurrence of 20-Hz fin whale sounds led Watkins to hypothesize a reproductive function similar to humpback (Megaptera novaeangliae) song, and by default this function has been extended to blue whale songs. More recent evidence shows that blue and fin whales produce infrasonic calls in high latitudes during the feeding season, and that singing is associated with areas of high productivity where females congregate to feed. Acoustic sampling over broad spatial and temporal scales for baleen species is revealing higher geographic and seasonal variability in the low-frequency vocal behaviors than previously reported, suggesting that present explanations for baleen whale sounds are too simplistic.

Effect of advective flow in fractures and matrix diffusion on natural gas production

DOE PAGES

Karra, Satish; Makedonska, Nataliia; Viswanathan, Hari S.; ...

2015-10-12

Although hydraulic fracturing has been used for natural gas production for the past couple of decades, there are significant uncertainties about the underlying mechanisms behind the production curves that are seen in the field. A discrete fracture network based reservoir-scale work flow is used to identify the relative effect of flow of gas in fractures and matrix diffusion on the production curve. With realistic three dimensional representations of fracture network geometry and aperture variability, simulated production decline curves qualitatively resemble observed production decline curves. The high initial peak of the production curve is controlled by advective fracture flow of freemore » gas within the network and is sensitive to the fracture aperture variability. Matrix diffusion does not significantly affect the production decline curve in the first few years, but contributes to production after approximately 10 years. These results suggest that the initial flushing of gas-filled background fractures combined with highly heterogeneous flow paths to the production well are sufficient to explain observed initial production decline. Lastly, these results also suggest that matrix diffusion may support reduced production over longer time frames.« less

A spectro-interferometric view of l Carinae's modulated pulsations

NASA Astrophysics Data System (ADS)

Anderson, Richard I.; Mérand, Antoine; Kervella, Pierre; Breitfelder, Joanne; Eyer, Laurent; Gallenne, Alexandre

Classical Cepheids are radially pulsating stars that enable important tests of stellar evolution and play a crucial role in the calibration of the local Hubble constant. l Carinae is a particularly well-known distance calibrator, being the closest long-period (P ~ 35.5 d) Cepheid and subtending the largest angular diameter. We have carried out an unprecedented observing program to investigate whether recently discovered cycle-to-cycle changes (modulations) of l Carinae's radial velocity (RV) variability are mirrored by its variability in angular size. To this end, we have secured a fully contemporaneous dataset of high-precision RVs and high-precision angular diameters. Here we provide a concise summary of our project and report preliminary results. We confirm the modulated nature of the RV variability and find tentative evidence of cycle-to-cycle differences in l Car's maximal angular diameter. Our analysis is exploring the limits of state-of-the-art instrumentation and reveals additional complexity in the pulsations of Cepheids. If confirmed, our result suggests a previously unknown pulsation cycle dependence of projection factors required for determining Cepheid distances via the Baade-Wesselink technique.

Population-environment drivers of H5N1 avian influenza molecular change in Vietnam

PubMed Central

Carrel, Margaret A.; Emch, Michael; Nguyen, Tung; Jobe, R. Todd; Wan, Xiu-Feng

2013-01-01

This study identifies population and environment drivers of genetic change in H5N1 avian influenza viruses (AIV) in Vietnam using a landscape genetics approach. While prior work has examined how combinations of local-level environmental variables influence H5N1 occurrence, this research expands the analysis to the complex genetic characteristics of H5N1 viruses. A dataset of 125 highly pathogenic H5N1 AIV isolated in Vietnam from 2003–2007 is used to explore which population and environment variables are correlated with increased genetic change among viruses. Results from non-parametric multidimensional scaling and regression analyses indicate that variables relating to both the environmental and social ecology of humans and birds in Vietnam interact to affect the genetic character of viruses. These findings suggest that it is a combination of suitable environments for species mixing, the presence of high numbers of potential hosts, and in particular the temporal characteristics of viral occurrence, that drive genetic change among H5N1 AIV in Vietnam. PMID:22652510

Population-environment drivers of H5N1 avian influenza molecular change in Vietnam.

PubMed

Carrel, Margaret A; Emch, Michael; Nguyen, Tung; Todd Jobe, R; Wan, Xiu-Feng

2012-09-01

This study identifies population and environment drivers of genetic change in H5N1 avian influenza viruses (AIV) in Vietnam using a landscape genetics approach. While prior work has examined how combinations of local-level environmental variables influence H5N1 occurrence, this research expands the analysis to the complex genetic characteristics of H5N1 viruses. A dataset of 125 highly pathogenic H5N1 AIV isolated in Vietnam from 2003 to 2007 is used to explore which population and environment variables are correlated with increased genetic change among viruses. Results from non-parametric multidimensional scaling and regression analyses indicate that variables relating to both the environmental and social ecology of humans and birds in Vietnam interact to affect the genetic character of viruses. These findings suggest that it is a combination of suitable environments for species mixing, the presence of high numbers of potential hosts, and in particular the temporal characteristics of viral occurrence, that drive genetic change among H5N1 AIV in Vietnam. Copyright © 2012 Elsevier Ltd. All rights reserved.

Enter the Dragon: The Dynamic and Multifunctional Evolution of Anguimorpha Lizard Venoms

PubMed Central

Koludarov, Ivan; Jackson, Timothy NW; op den Brouw, Bianca; Dobson, James; Dashevsky, Daniel; Clemente, Christofer J.; Stockdale, Edward J.; Cochran, Chip; Debono, Jordan; Stephens, Carson; Panagides, Nadya; Li, Bin; Roy Manchadi, Mary-Louise; Violette, Aude; Fourmy, Rudy; Hendrikx, Iwan; Nouwens, Amanda; Clements, Judith; Martelli, Paolo; Kwok, Hang Fai; Fry, Bryan G.

2017-01-01

While snake venoms have been the subject of intense study, comparatively little work has been done on lizard venoms. In this study, we have examined the structural and functional diversification of anguimorph lizard venoms and associated toxins, and related these results to dentition and predatory ecology. Venom composition was shown to be highly variable across the 20 species of Heloderma, Lanthanotus, and Varanus included in our study. While kallikrein enzymes were ubiquitous, they were also a particularly multifunctional toxin type, with differential activities on enzyme substrates and also ability to degrade alpha or beta chains of fibrinogen that reflects structural variability. Examination of other toxin types also revealed similar variability in their presence and activity levels. The high level of venom chemistry variation in varanid lizards compared to that of helodermatid lizards suggests that venom may be subject to different selection pressures in these two families. These results not only contribute to our understanding of venom evolution but also reveal anguimorph lizard venoms to be rich sources of novel bioactive molecules with potential as drug design and development lead compounds. PMID:28783084

Enter the Dragon: The Dynamic and Multifunctional Evolution of Anguimorpha Lizard Venoms.

PubMed

Koludarov, Ivan; Jackson, Timothy Nw; Brouw, Bianca Op den; Dobson, James; Dashevsky, Daniel; Arbuckle, Kevin; Clemente, Christofer J; Stockdale, Edward J; Cochran, Chip; Debono, Jordan; Stephens, Carson; Panagides, Nadya; Li, Bin; Manchadi, Mary-Louise Roy; Violette, Aude; Fourmy, Rudy; Hendrikx, Iwan; Nouwens, Amanda; Clements, Judith; Martelli, Paolo; Kwok, Hang Fai; Fry, Bryan G

2017-08-06

While snake venoms have been the subject of intense study, comparatively little work has been done on lizard venoms. In this study, we have examined the structural and functional diversification of anguimorph lizard venoms and associated toxins, and related these results to dentition and predatory ecology. Venom composition was shown to be highly variable across the 20 species of Heloderma , Lanthanotus , and Varanus included in our study. While kallikrein enzymes were ubiquitous, they were also a particularly multifunctional toxin type, with differential activities on enzyme substrates and also ability to degrade alpha or beta chains of fibrinogen that reflects structural variability. Examination of other toxin types also revealed similar variability in their presence and activity levels. The high level of venom chemistry variation in varanid lizards compared to that of helodermatid lizards suggests that venom may be subject to different selection pressures in these two families. These results not only contribute to our understanding of venom evolution but also reveal anguimorph lizard venoms to be rich sources of novel bioactive molecules with potential as drug design and development lead compounds.

Spatial variability and response to anthropogenic pressures of assemblages dominated by a habitat forming seaweed sensitive to pollution (northern coast of Alboran Sea).

PubMed

Bermejo, Ricardo; de la Fuente, Gina; Ramírez-Romero, Eduardo; Vergara, Juan J; Hernández, Ignacio

2016-04-15

The Cystoseira ericaefolia group is conformed by three species: C. tamariscifolia, C. mediterranea and C. amentacea. These species are among the most important habitat forming species of the upper sublittoral rocky shores of the Mediterranean Sea and adjacent Atlantic coast. This species group is sensitive to human pressures and therefore is currently suffering important losses. This study aimed to assess the influence of anthropogenic pressures, oceanographic conditions and local spatial variability in assemblages dominated by C. ericaefolia in the Alboran Sea. The results showed the absence of significant effects of anthropogenic pressures or its interactions with environmental conditions in the Cystoseira assemblages. This fact was attributed to the high spatial variability, which is most probably masking the impact of anthropogenic pressures. The results also showed that most of the variability occurred on at local levels. A relevant spatial variability was observed at regional level, suggesting a key role of oceanographic features in these assemblages. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bivariate and multivariate analyses of the correlations between stability of the erythrocyte membrane, serum lipids and hematological variables.

PubMed

Bernardino Neto, M; de Avelar, E B; Arantes, T S; Jordão, I A; da Costa Huss, J C; de Souza, T M T; de Souza Penha, V A; da Silva, S C; de Souza, P C A; Tavares, M; Penha-Silva, N

2013-01-01

The observation that the fluidity must remain within a critical interval, outside which the stability and functionality of the cell tends to decrease, shows that stability, fluidity and function are related and that the measure of erythrocyte stability allows inferences about the fluidity or functionality of these cells. This study determined the biochemical and hematological variables that are directly or indirectly related to erythrocyte stability in a population of 71 volunteers. Data were evaluated by bivariate and multivariate analysis. The erythrocyte stability showed a greater association with hematological variables than the biochemical variables. The RDW stands out for its strong correlation with the stability of erythrocyte membrane, without being heavily influenced by other factors. Regarding the biochemical variables, the erythrocyte stability was more sensitive to LDL-C. Erythrocyte stability was significantly associated with RDW and LDL-C. Thus, the level of LDL-C is a consistent link between stability and functionality, suggesting that a measure of stability could be more one indirect parameter for assessing the risk of degenerative processes associated with high levels of LDL-C.

Individual differences affecting caffeine intake. Analysis of consumption behaviours for different times of day and caffeine sources.

PubMed

Penolazzi, Barbara; Natale, Vincenzo; Leone, Luigi; Russo, Paolo Maria

2012-06-01

The main purpose of the present study was to investigate the individual variables contributing to determine the high variability in the consumption behaviours of caffeine, a psychoactive substance which is still poorly investigated in comparison with other drugs. The effects of a large set of specific personality traits (i.e., Impulsivity, Sensation Seeking, Anxiety, Reward Sensitivity and Circadian Preference) were compared along with some relevant socio-demographic variables (i.e., gender and age) and cigarette smoking behaviour. Analyses revealed that daily caffeine intake was significantly higher for males, older people, participants smoking more cigarettes and showing higher scores on Impulsivity, Sensation Seeking and a facet of Reward Sensitivity. However, more detailed analyses showed that different patterns of individual variables predicted caffeine consumption when the times of day and the caffeine sources were considered. The present results suggest that such detailed analyses are required to detect the critical predictive variables that could be obscured when only total caffeine intake during the entire day is considered. Copyright © 2012 Elsevier Ltd. All rights reserved.

Changes in the genetic structure of Atlantic salmon populations over four decades reveal substantial impacts of stocking and potential resiliency

PubMed Central

Perrier, Charles; Guyomard, René; Bagliniere, Jean-Luc; Nikolic, Natacha; Evanno, Guillaume

2013-01-01

While the stocking of captive-bred fish has been occurring for decades and has had substantial immediate genetic and evolutionary impacts on wild populations, its long-term consequences have only been weakly investigated. Here, we conducted a spatiotemporal analysis of 1428 Atlantic salmon sampled from 1965 to 2006 in 25 populations throughout France to investigate the influence of stocking on the neutral genetic structure in wild Atlantic salmon (Salmo salar) populations. On the basis of the analysis of 11 microsatellite loci, we found that the overall genetic structure among populations dramatically decreased over the period studied. Admixture rates among populations were highly variable, ranging from a nearly undetectable contribution from donor stocks to total replacement of the native gene pool, suggesting extremely variable impacts of stocking. Depending on population, admixture rates either increased, remained stable, or decreased in samples collected between 1998 and 2006 compared to samples from 1965 to 1987, suggesting either rising, long-lasting or short-term impacts of stocking. We discuss the potential mechanisms contributing to this variability, including the reduced fitness of stocked fish and persistence of wild locally adapted individuals. PMID:23919174

The transiting dust clumps in the evolved disc of the Sun-like UXor RZ Psc

PubMed Central

Kenworthy, Matthew A.; Pepper, Joshua; Rodriguez, Joseph E.; Siverd, Robert J.; Stassun, Keivan G.; Wyatt, Mark C.

2017-01-01

RZ Psc is a young Sun-like star, long associated with the UXor class of variable stars, which is partially or wholly dimmed by dust clumps several times each year. The system has a bright and variable infrared excess, which has been interpreted as evidence that the dimming events are the passage of asteroidal fragments in front of the host star. Here, we present a decade of optical photometry of RZ Psc and take a critical look at the asteroid belt interpretation. We show that the distribution of light curve gradients is non-uniform for deep events, which we interpret as possible evidence for an asteroidal fragment-like clump structure. However, the clumps are very likely seen above a high optical depth midplane, so the disc’s bulk clumpiness is not revealed. While circumstantial evidence suggests an asteroid belt is more plausible than a gas-rich transition disc, the evolutionary status remains uncertain. We suggest that the rarity of Sun-like stars showing disc-related variability may arise because (i) any accretion streams are transparent and/or (ii) turbulence above the inner rim is normally shadowed by a flared outer disc. PMID:28280566

Stigma predicts residential treatment length for substance use disorder

PubMed Central

Luoma, Jason B.; Kulesza, Magdalena; Hayes, Steven C.; Kohlenberg, Barbara; Larimer, Mary

2016-01-01

Background Stigma has been suggested as a possible contributor to the high rates of treatment attrition in substance-dependent individuals, but no published empirical studies have examined this association. Objectives The present paper assessed the relationship between baseline stigma variables and length of treatment stay in a sample of patients in a residential addictions treatment unit. Methods The relationship between baseline stigma variables (self-stigma, enacted stigma, and shame) and length of stay for participants (n = 103) in a residential addictions treatment unit was examined. Results Higher self-stigma predicted longer stay in residential addictions treatment, even after controlling for age, marital status, race, overall mental health, social support, enacted stigma, and internalized shame. However, other stigma variables (i.e. internalized shame, stigma-related rejection) did not reliably predict length of treatment stay. Conclusion These results are consistent with other findings suggesting that people with higher self-stigma may have a lowered sense of self-efficacy and heightened fear of being stigmatized and therefore retreat into more protected settings such as residential treatment, potentially resulting in higher treatment costs. Specialized clinical interventions may be necessary to help participants cope with reduced self-efficacy and fear of being stigmatized. PMID:24766087

The transiting dust clumps in the evolved disc of the Sun-like UXor RZ Psc.

PubMed

Kennedy, Grant M; Kenworthy, Matthew A; Pepper, Joshua; Rodriguez, Joseph E; Siverd, Robert J; Stassun, Keivan G; Wyatt, Mark C

2017-01-01

RZ Psc is a young Sun-like star, long associated with the UXor class of variable stars, which is partially or wholly dimmed by dust clumps several times each year. The system has a bright and variable infrared excess, which has been interpreted as evidence that the dimming events are the passage of asteroidal fragments in front of the host star. Here, we present a decade of optical photometry of RZ Psc and take a critical look at the asteroid belt interpretation. We show that the distribution of light curve gradients is non-uniform for deep events, which we interpret as possible evidence for an asteroidal fragment-like clump structure. However, the clumps are very likely seen above a high optical depth midplane, so the disc's bulk clumpiness is not revealed. While circumstantial evidence suggests an asteroid belt is more plausible than a gas-rich transition disc, the evolutionary status remains uncertain. We suggest that the rarity of Sun-like stars showing disc-related variability may arise because (i) any accretion streams are transparent and/or (ii) turbulence above the inner rim is normally shadowed by a flared outer disc.

The transiting dust clumps in the evolved disc of the Sun-like UXor RZ Psc

NASA Astrophysics Data System (ADS)

Kennedy, Grant M.; Kenworthy, Matthew A.; Pepper, Joshua; Rodriguez, Joseph E.; Siverd, Robert J.; Stassun, Keivan G.; Wyatt, Mark C.

2017-01-01

RZ Psc is a young Sun-like star, long associated with the UXor class of variable stars, which is partially or wholly dimmed by dust clumps several times each year. The system has a bright and variable infrared excess, which has been interpreted as evidence that the dimming events are the passage of asteroidal fragments in front of the host star. Here, we present a decade of optical photometry of RZ Psc and take a critical look at the asteroid belt interpretation. We show that the distribution of light curve gradients is non-uniform for deep events, which we interpret as possible evidence for an asteroidal fragment-like clump structure. However, the clumps are very likely seen above a high optical depth midplane, so the disc's bulk clumpiness is not revealed. While circumstantial evidence suggests an asteroid belt is more plausible than a gas-rich transition disc, the evolutionary status remains uncertain. We suggest that the rarity of Sun-like stars showing disc-related variability may arise because (i) any accretion streams are transparent and/or (ii) turbulence above the inner rim is normally shadowed by a flared outer disc.

Factors regulating year‐class strength of Silver Carp throughout the Mississippi River basin

USGS Publications Warehouse

Sullivan, Christopher J.; Weber, Michael J.; Pierce, Clay; Wahl, David H.; Phelps, Quinton E.; Camacho, Carlos A.; Colombo, Robert E.

2018-01-01

Recruitment of many fish populations is inherently highly variable inter‐annually. However, this variability can be synchronous at broad geographic scales due to fish dispersal and climatic conditions. Herein, we investigated recruitment synchrony of Silver Carp Hypophthalmichthys molitrix across the Mississippi River basin. Year‐class strength (YCS) and synchrony of nine populations (max linear distance = 806.4 km) was indexed using catch‐curve residuals correlated between sites and related to local and regional climatic conditions. Overall, Silver Carp YCS was not synchronous among populations, suggesting local environmental factors are more important determinants of YCS than large‐scale environmental factors. Variation in Silver Carp YCS was influenced by river base flow and discharge variability at each site, indicating that extended periods of static local discharge benefit YCS. Further, river discharge and air temperature were correlated and synchronized among sites, but only similarities in river discharge was correlated with Silver Carp population synchrony, indicating that similarities in discharge (i.e., major flood) among sites can positively synchronize Silver Carp YCS. The positive correlation between Silver Carp YCS and river discharge synchrony suggests that regional flood regimes are an important force determining the degree of population synchrony among Mississippi River Silver Carp populations.

Negative Mood and Obsessive-Compulsive Related Clinical Constructs: An Examination of Underlying Factors

PubMed Central

Britton, Gary I.; Davey, Graham C. L.

2017-01-01

Emerging evidence suggests that many of the clinical constructs used to help understand and explain obsessive-compulsive (OC) symptoms, and negative mood, may be causally interrelated. One approach to understanding this interrelatedness is a motivational systems approach. This approach suggests that rather than considering clinical constructs and negative affect as separable entities, they are all features of an integrated threat management system, and as such are highly coordinated and interdependent. The aim of the present study was to examine if clinical constructs related to OC symptoms and negative mood are best treated as separable or, alternatively, if these clinical constructs and negative mood are best seen as indicators of an underlying superordinate variable, as would be predicted by a motivational systems approach. A sample of 370 student participants completed measures of mood and the clinical constructs of inflated responsibility, intolerance of uncertainty, not just right experiences, and checking stop rules. An exploratory factor analysis suggested two plausible factor structures, one where all construct items and negative mood items loaded onto one underlying superordinate variable, and a second structure comprising of five factors, where each item loaded onto a factor representative of what the item was originally intended to measure. A confirmatory factor analysis showed that the five factor model was preferential to the one factor model, suggesting the four constructs and negative mood are best conceptualized as separate variables. Given the predictions of a motivational systems approach were not supported in the current study, other possible explanations for the causal interrelatedness between clinical constructs and negative mood are discussed. PMID:28959224

Very high energy gamma ray astronomy

NASA Technical Reports Server (NTRS)

Grindlay, J. E.

1976-01-01

Recent results in ground based very high energy gamma ray astronomy are reviewed. The various modes of the atmospheric Cerenkov technique are described, and the importance of cosmic ray rejection methods is stressed. The positive detections of the Crab pulsar that suggest a very flat spectrum and time-variable pulse phase are discussed. Observations of other pulsars (particularly Vela) suggest these features may be general. Evidence that a 4.8 hr modulated effect was detected from Cyg X-3 is strengthened in that the exact period originally proposed agrees well with a recent determination of the X-ray period. The southern sky observations are reviewed, and the significance of the detection of an active galaxy (NGC 5128) is considered for source models and future observations.

Taking the pulse of mountains: Ecosystem responses to climatic variability

USGS Publications Warehouse

Fagre, Daniel B.; Peterson, David L.; Hessl, Amy E.

2003-01-01

An integrated program of ecosystem modeling and field studies in the mountains of the Pacific Northwest (U.S.A.) has quantified many of the ecological processes affected by climatic variability. Paleoecological and contemporary ecological data in forest ecosystems provided model parameterization and validation at broad spatial and temporal scales for tree growth, tree regeneration and treeline movement. For subalpine tree species, winter precipitation has a strong negative correlation with growth; this relationship is stronger at higher elevations and west-side sites (which have more precipitation). Temperature affects tree growth at some locations with respect to length of growing season (spring) and severity of drought at drier sites (summer). Furthermore, variable but predictable climate-growth relationships across elevation gradients suggest that tree species respond differently to climate at different locations, making a uniform response of these species to future climatic change unlikely. Multi-decadal variability in climate also affects ecosystem processes. Mountain hemlock growth at high-elevation sites is negatively correlated with winter snow depth and positively correlated with the winter Pacific Decadal Oscillation (PDO) index. At low elevations, the reverse is true. Glacier mass balance and fire severity are also linked to PDO. Rapid establishment of trees in subalpine ecosystems during this century is increasing forest cover and reducing meadow cover at many subalpine locations in the western U.S.A. and precipitation (snow depth) is a critical variable regulating conifer expansion. Lastly, modeling potential future ecosystem conditions suggests that increased climatic variability will result in increasing forest fire size and frequency, and reduced net primary productivity in drier, east-side forest ecosystems. As additional empirical data and modeling output become available, we will improve our ability to predict the effects of climatic change across a broad range of climates and mountain ecosystems in the northwestern U.S.A.

Mapping of Variable DNA Methylation Across Multiple Cell Types Defines a Dynamic Regulatory Landscape of the Human Genome.

PubMed

Gu, Junchen; Stevens, Michael; Xing, Xiaoyun; Li, Daofeng; Zhang, Bo; Payton, Jacqueline E; Oltz, Eugene M; Jarvis, James N; Jiang, Kaiyu; Cicero, Theodore; Costello, Joseph F; Wang, Ting

2016-04-07

DNA methylation is an important epigenetic modification involved in many biological processes and diseases. Many studies have mapped DNA methylation changes associated with embryogenesis, cell differentiation, and cancer at a genome-wide scale. Our understanding of genome-wide DNA methylation changes in a developmental or disease-related context has been steadily growing. However, the investigation of which CpGs are variably methylated in different normal cell or tissue types is still limited. Here, we present an in-depth analysis of 54 single-CpG-resolution DNA methylomes of normal human cell types by integrating high-throughput sequencing-based methylation data. We found that the ratio of methylated to unmethylated CpGs is relatively constant regardless of cell type. However, which CpGs made up the unmethylated complement was cell-type specific. We categorized the 26,000,000 human autosomal CpGs based on their methylation levels across multiple cell types to identify variably methylated CpGs and found that 22.6% exhibited variable DNA methylation. These variably methylated CpGs formed 660,000 variably methylated regions (VMRs), encompassing 11% of the genome. By integrating a multitude of genomic data, we found that VMRs enrich for histone modifications indicative of enhancers, suggesting their role as regulatory elements marking cell type specificity. VMRs enriched for transcription factor binding sites in a tissue-dependent manner. Importantly, they enriched for GWAS variants, suggesting that VMRs could potentially be implicated in disease and complex traits. Taken together, our results highlight the link between CpG methylation variation, genetic variation, and disease risk for many human cell types. Copyright © 2016 Gu et al.

Does internal climate variability overwhelm climate change signals in streamflow? The upper Po and Rhone basin case studies.

PubMed

Fatichi, S; Rimkus, S; Burlando, P; Bordoy, R

2014-09-15

Projections of climate change effects in streamflow are increasingly required to plan water management strategies. These projections are however largely uncertain due to the spread among climate model realizations, internal climate variability, and difficulties in transferring climate model results at the spatial and temporal scales required by catchment hydrology. A combination of a stochastic downscaling methodology and distributed hydrological modeling was used in the ACQWA project to provide projections of future streamflow (up to year 2050) for the upper Po and Rhone basins, respectively located in northern Italy and south-western Switzerland. Results suggest that internal (stochastic) climate variability is a fundamental source of uncertainty, typically comparable or larger than the projected climate change signal. Therefore, climate change effects in streamflow mean, frequency, and seasonality can be masked by natural climatic fluctuations in large parts of the analyzed regions. An exception to the overwhelming role of stochastic variability is represented by high elevation catchments fed by glaciers where streamflow is expected to be considerably reduced due to glacier retreat, with consequences appreciable in the main downstream rivers in August and September. Simulations also identify regions (west upper Rhone and Toce, Ticino river basins) where a strong precipitation increase in the February to April period projects streamflow beyond the range of natural climate variability during the melting season. This study emphasizes the importance of including internal climate variability in climate change analyses, especially when compared to the limited uncertainty that would be accounted for by few deterministic projections. The presented results could be useful in guiding more specific impact studies, although design or management decisions should be better based on reliability and vulnerability criteria as suggested by recent literature. Copyright © 2013 Elsevier B.V. All rights reserved.

Inter and intra-system size variability of reverse shoulder arthroplasty polyethylene inserts

PubMed Central

Teeter, Matthew G.; Dawson, Matthew T.; Athwal, George S.

2016-01-01

Background: As the incidence of reverse shoulder arthroplasty (RSA) increases, so will the revision burden. At times, the revision surgeon may be faced with a well-fixed component on one side of the joint and revision implants from a different manufacturer. The ability to use glenoid and humeral implants from different manufacturers could simplify the revision procedure. This study hypothesized that across a range of RSA systems, some implants would demonstrate high size compatibility and others would demonstrate low compatibility. Materials and Methods: Six polyethylene inserts each from eight reverse total shoulder arthroplasty systems were examined (48 total inserts). All inserts were scanned using a laboratory micro-computed tomography scanner at 50 μm isotropic voxel spacing, and their surface geometries were reconstructed. The different implant geometries were co-registered, and the three-dimensional (3D) variability between the articular surfaces of the different implant systems was measured. Intrasystem manufacturing variability was also determined by measuring the 3D variability of inserts from the same system. Results: The intersystem polyethylene articular surface deviations between same-size systems were not significantly different (P = 0.61) and were a mean maximum of 60 ± 16 μm (range: 30-80 μm). Intrasystem manufacturing variability was equivalent between all but two models, averaging 49 ± 17 μm (range: 23-99 μm). Discussion: Differences in articular geometry between same-size inserts from different systems were on the same scale as intrasystem manufacturing variability, suggesting that different implant systems of the same nominal diameter could potentially be used interchangeably in revision or extenuating circumstances. Conclusion: The results of this study suggest that surgeons can theoretically interchange same-sized implant components from the different RSA systems tested when conducting revisions. PMID:26980984

Environment and genotype effects on the content of dietary fiber and its components in wheat in the HEALTHGRAIN diversity screen.

PubMed

Gebruers, Kurt; Dornez, Emmie; Bedõ, Zoltan; Rakszegi, Mariann; Frás, Anna; Boros, Danuta; Courtin, Christophe M; Delcour, Jan A

2010-09-08

Within the HEALTHGRAIN diversity screen, the variability of the contents of dietary fiber (DF) and components thereof was studied in wheat. Furthermore, the contribution of genotype and environment to this variability was estimated. The levels of total DF (TDF), total nonstarch polysaccharide (TOTNSP), water-extractable nonstarch polysaccharide (WENSP), total arabinoxylan (TOTAX), lignin, and beta-glucan in whole meal, flour, and/or bran varied approximately 1.8-fold. The highest variability was observed for the water-extractable arabinoxylan (WEAX) level in flour and bran (approximately 3.7-fold). Genotype and environment contributed to a similar extent to the variability in TDF, TOTNSP, and TOTAX content in wheat. The observed relatively high impact of genotype-environment interaction suggests that the levels of these constituents are weak breeding parameters. The WENSP level is a more stable parameter as the effect of the interaction term was much less than the impact of genotype. For TOTAX and WEAX in flour, WEAX in bran, beta-glucan in whole meal, and extract viscosity, wheat genotype determined approximately 50% or higher of the variation observed, whereas the impact of the genotype-environment interaction was relatively low. These findings suggest that the health-related and technological functionality of wheat can be directed to a certain extent by selection of appropriate wheat varieties.

Complexity in relational processing predicts changes in functional brain network dynamics.

PubMed

Cocchi, Luca; Halford, Graeme S; Zalesky, Andrew; Harding, Ian H; Ramm, Brentyn J; Cutmore, Tim; Shum, David H K; Mattingley, Jason B

2014-09-01

The ability to link variables is critical to many high-order cognitive functions, including reasoning. It has been proposed that limits in relating variables depend critically on relational complexity, defined formally as the number of variables to be related in solving a problem. In humans, the prefrontal cortex is known to be important for reasoning, but recent studies have suggested that such processes are likely to involve widespread functional brain networks. To test this hypothesis, we used functional magnetic resonance imaging and a classic measure of deductive reasoning to examine changes in brain networks as a function of relational complexity. As expected, behavioral performance declined as the number of variables to be related increased. Likewise, increments in relational complexity were associated with proportional enhancements in brain activity and task-based connectivity within and between 2 cognitive control networks: A cingulo-opercular network for maintaining task set, and a fronto-parietal network for implementing trial-by-trial control. Changes in effective connectivity as a function of increased relational complexity suggested a key role for the left dorsolateral prefrontal cortex in integrating and implementing task set in a trial-by-trial manner. Our findings show that limits in relational processing are manifested in the brain as complexity-dependent modulations of large-scale networks. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Hypnosis, suggestion, and suggestibility: an integrative model.

PubMed

Lynn, Steven Jay; Laurence, Jean-Roch; Kirsch, Irving

2015-01-01

This article elucidates an integrative model of hypnosis that integrates social, cultural, cognitive, and neurophysiological variables at play both in and out of hypnosis and considers their dynamic interaction as determinants of the multifaceted experience of hypnosis. The roles of these variables are examined in the induction and suggestion stages of hypnosis, including how they are related to the experience of involuntariness, one of the hallmarks of hypnosis. It is suggested that studies of the modification of hypnotic suggestibility; cognitive flexibility; response sets and expectancies; the default-mode network; and the search for the neurophysiological correlates of hypnosis, more broadly, in conjunction with research on social psychological variables, hold much promise to further understanding of hypnosis.

gHRV: Heart rate variability analysis made easy.

PubMed

Rodríguez-Liñares, L; Lado, M J; Vila, X A; Méndez, A J; Cuesta, P

2014-08-01

In this paper, the gHRV software tool is presented. It is a simple, free and portable tool developed in python for analysing heart rate variability. It includes a graphical user interface and it can import files in multiple formats, analyse time intervals in the signal, test statistical significance and export the results. This paper also contains, as an example of use, a clinical analysis performed with the gHRV tool, namely to determine whether the heart rate variability indexes change across different stages of sleep. Results from tests completed by researchers who have tried gHRV are also explained: in general the application was positively valued and results reflect a high level of satisfaction. gHRV is in continuous development and new versions will include suggestions made by testers. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

The Acute Effects of Aerobic Exercise on Cognitive Flexibility and Task-Related Heart Rate Variability in Children With ADHD and Healthy Controls.

PubMed

Ludyga, Sebastian; Gerber, Markus; Mücke, Manuel; Brand, Serge; Weber, Peter; Brotzmann, Mark; Pühse, Uwe

2018-02-01

To investigate cognitive flexibility and task-related heart rate variability following moderately intense aerobic exercise and after watching a video in both children with ADHD and healthy controls. Using a cross-over design, participants completed cognitive assessments following exercise and a physically inactive control condition. Behavioral performance was assessed using the Alternate Uses task. Heart rate variability was recorded via electrocardiography during the cognitive task. The statistical analysis revealed that in comparison with the control condition, both groups showed higher cognitive flexibility following aerobic exercise. Moreover, decreased low frequency and high frequency power was observed in the exercise condition. The findings suggest that exercise elicits similar benefits for cognitive flexibility in children with ADHD and healthy controls, partly due to an increase in arousal induced by parasympathetic withdrawal.

The X-ray spectra of the BL Lacertae objects PKS 0548 - 322 and 3C 66A

NASA Technical Reports Server (NTRS)

Maccacaro, T.; Maccagni, D.; Tarenghi, M.

1983-01-01

Einstein Observatory simultaneous imaging proportional counter and monitor proportional counter data are combined in order to derive the energy spectra of the BL Lac objects PKS 0548-322 and 3C 66A between 0.2 and 10 keV. While the latter is found to be variable in both intensity and spectral shape, the former, although constant in the present data, is found to have experienced a spectrum variation in view of results from other experiments. Attention is given to the implications of flux and spectral variability in BL Lac objects for models of X-ray emission mechanisms. It is suggested that the wide spread of the spectral index distribution is due to the detection of the highly variable synchrotron-produced X-rays that are generally undetected in QSOs.

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

Schmidt, Edward G.; Hemen, Brian; Rogalla, Danielle

We have obtained VR photometry of 282 Cepheid variable star candidates from the northern part of the All Sky Automated Survey (ASAS). These together with data from the ASAS and the Northern Sky Variability Survey (NSVS) were used to redetermine the periods of the stars. We divided the stars into four groups based on location in a plot of mean color, (V-R), versus period. Two of the groups fell within the region of the diagram containing known type II Cepheids and yielded 14 new highly probable type II Cepheids. The properties of the remaining stars in these two groups aremore » discussed but their nature remains uncertain. Unexplained differences exist between the sample of stars studied here and a previous sample drawn from the NSVS by Akerlof et al. This suggests serious biases in the identification of variables in different surveys.« less

Interrelation of changes in the total content of ozone in the northern hemisphere with the velocity of the stratosphere circumpolar vortex

NASA Astrophysics Data System (ADS)

Kolyada, Maria N.; Kashkin, Valentin B.

2004-12-01

Considering the high significance of the ozone for preservation and maintenance of the biosphere and the temperature balance of the atmosphere the investigation of the ozone layer is a very important part of the investigation of the planet"s atmosphere. In this work results of investigations of TOC variability in the Northern Hemisphere and the influence of variability of the circumpolar vortex rotation velocity on the ozone layer are presented. Mean values of total ozone concentration in the Northern Hemisphere (by satellite data) and rotation velocities of the circumpolar vortex are calculated for each month from February to April during 1998-2004. Also in this work the mechanism of the influence of the natural factors on TOC variability solar activity during the spring is suggested.

Classification of ROTSE Variable Stars using Machine Learning

NASA Astrophysics Data System (ADS)

Wozniak, P. R.; Akerlof, C.; Amrose, S.; Brumby, S.; Casperson, D.; Gisler, G.; Kehoe, R.; Lee, B.; Marshall, S.; McGowan, K. E.; McKay, T.; Perkins, S.; Priedhorsky, W.; Rykoff, E.; Smith, D. A.; Theiler, J.; Vestrand, W. T.; Wren, J.; ROTSE Collaboration

2001-12-01

We evaluate several Machine Learning algorithms as potential tools for automated classification of variable stars. Using the ROTSE sample of ~1800 variables from a pilot study of 5% of the whole sky, we compare the effectiveness of a supervised technique (Support Vector Machines, SVM) versus unsupervised methods (K-means and Autoclass). There are 8 types of variables in the sample: RR Lyr AB, RR Lyr C, Delta Scuti, Cepheids, detached eclipsing binaries, contact binaries, Miras and LPVs. Preliminary results suggest a very high ( ~95%) efficiency of SVM in isolating a few best defined classes against the rest of the sample, and good accuracy ( ~70-75%) for all classes considered simultaneously. This includes some degeneracies, irreducible with the information at hand. Supervised methods naturally outperform unsupervised methods, in terms of final error rate, but unsupervised methods offer many advantages for large sets of unlabeled data. Therefore, both types of methods should be considered as promising tools for mining vast variability surveys. We project that there are more than 30,000 periodic variables in the ROTSE-I data base covering the entire local sky between V=10 and 15.5 mag. This sample size is already stretching the time capabilities of human analysts.

Physical attraction to reliable, low variability nervous systems: Reaction time variability predicts attractiveness.

PubMed

Butler, Emily E; Saville, Christopher W N; Ward, Robert; Ramsey, Richard

2017-01-01

The human face cues a range of important fitness information, which guides mate selection towards desirable others. Given humans' high investment in the central nervous system (CNS), cues to CNS function should be especially important in social selection. We tested if facial attractiveness preferences are sensitive to the reliability of human nervous system function. Several decades of research suggest an operational measure for CNS reliability is reaction time variability, which is measured by standard deviation of reaction times across trials. Across two experiments, we show that low reaction time variability is associated with facial attractiveness. Moreover, variability in performance made a unique contribution to attractiveness judgements above and beyond both physical health and sex-typicality judgements, which have previously been associated with perceptions of attractiveness. In a third experiment, we empirically estimated the distribution of attractiveness preferences expected by chance and show that the size and direction of our results in Experiments 1 and 2 are statistically unlikely without reference to reaction time variability. We conclude that an operating characteristic of the human nervous system, reliability of information processing, is signalled to others through facial appearance. Copyright © 2016 Elsevier B.V. All rights reserved.

Environmental variables measured at multiple spatial scales exert uneven influence on fish assemblages of floodplain lakes

USGS Publications Warehouse

Dembkowski, Daniel J.; Miranda, Leandro E.

2014-01-01

We examined the interaction between environmental variables measured at three different scales (i.e., landscape, lake, and in-lake) and fish assemblage descriptors across a range of over 50 floodplain lakes in the Mississippi Alluvial Valley of Mississippi and Arkansas. Our goal was to identify important local- and landscape-level determinants of fish assemblage structure. Relationships between fish assemblage structure and variables measured at broader scales (i.e., landscape-level and lake-level) were hypothesized to be stronger than relationships with variables measured at finer scales (i.e., in-lake variables). Results suggest that fish assemblage structure in floodplain lakes was influenced by variables operating on three different scales. However, and contrary to expectations, canonical correlations between in-lake environmental characteristics and fish assemblage structure were generally stronger than correlations between landscape-level and lake-level variables and fish assemblage structure, suggesting a hierarchy of influence. From a resource management perspective, our study suggests that landscape-level and lake-level variables may be manipulated for conservation or restoration purposes, and in-lake variables and fish assemblage structure may be used to monitor the success of such efforts.

Information content of IRIS spectra. [from Nimbus 4 satellite

NASA Technical Reports Server (NTRS)

Price, J. C.

1974-01-01

Spectra from the satellite instrument IRIS (infra red interferometer spectrometer) were examined to find the number of independent variables needed to describe these broadband high spectral resolution data. The radiated power in the atmospheric window from 771 to 981/cm was the first parameter chosen for fitting observed spectra. At succeeding levels of analysis the residual variability (observed spectrum - best fit spectrum) in an ensemble of observations was partioned into spectral eigenvectors. The eigenvector describing the largest fraction of this variability was examined for a strong spectral signature; the power in the corresponding spectral band was then used as the next fitting parameter. The measured power in nine spectral intervals, when inserted in the spectral fitting functions, was adequate to describe most spectra to within the noise level of IRIS. Considerations of relative signal strength and scales of atmospheric variability suggest a combination sounder (multichannel-broad field of view) scanner (window channel-small field of view) as an efficient observing instrument.

Enhanced biennial variability in the Pacific due to Atlantic capacitor effect.

PubMed

Wang, Lei; Yu, Jin-Yi; Paek, Houk

2017-03-20

The El Niño-Southern Oscillation (ENSO) and the variability in the Pacific subtropical highs (PSHs) have major impacts on social and ecological systems. Here we present an Atlantic capacitor effect mechanism to suggest that the Atlantic is a key pacemaker of the biennial variability in the Pacific including that in ENSO and the PSHs during recent decades. The 'charging' (that is, ENSO imprinting the North Tropical Atlantic (NTA) sea surface temperature (SST) via an atmospheric bridge mechanism) and 'discharging' (that is, the NTA SST triggering the following ENSO via a subtropical teleconnection mechanism) processes alternate, generating the biennial rhythmic changes in the Pacific. Since the early 1990s, a warmer Atlantic due to the positive phase of Atlantic multidecadal oscillation and global warming trend has provided more favourable background state for the Atlantic capacitor effect, giving rise to enhanced biennial variability in the Pacific that may increase the occurrence frequency of severe natural hazard events.

Enhanced biennial variability in the Pacific due to Atlantic capacitor effect

PubMed Central

Wang, Lei; Yu, Jin-Yi; Paek, Houk

2017-01-01

The El Niño-Southern Oscillation (ENSO) and the variability in the Pacific subtropical highs (PSHs) have major impacts on social and ecological systems. Here we present an Atlantic capacitor effect mechanism to suggest that the Atlantic is a key pacemaker of the biennial variability in the Pacific including that in ENSO and the PSHs during recent decades. The ‘charging' (that is, ENSO imprinting the North Tropical Atlantic (NTA) sea surface temperature (SST) via an atmospheric bridge mechanism) and ‘discharging' (that is, the NTA SST triggering the following ENSO via a subtropical teleconnection mechanism) processes alternate, generating the biennial rhythmic changes in the Pacific. Since the early 1990s, a warmer Atlantic due to the positive phase of Atlantic multidecadal oscillation and global warming trend has provided more favourable background state for the Atlantic capacitor effect, giving rise to enhanced biennial variability in the Pacific that may increase the occurrence frequency of severe natural hazard events. PMID:28317857

Enhanced biennial variability in the Pacific due to Atlantic capacitor effect

NASA Astrophysics Data System (ADS)

Wang, Lei; Yu, Jin-Yi; Paek, Houk

2017-03-01

The El Niño-Southern Oscillation (ENSO) and the variability in the Pacific subtropical highs (PSHs) have major impacts on social and ecological systems. Here we present an Atlantic capacitor effect mechanism to suggest that the Atlantic is a key pacemaker of the biennial variability in the Pacific including that in ENSO and the PSHs during recent decades. The `charging' (that is, ENSO imprinting the North Tropical Atlantic (NTA) sea surface temperature (SST) via an atmospheric bridge mechanism) and `discharging' (that is, the NTA SST triggering the following ENSO via a subtropical teleconnection mechanism) processes alternate, generating the biennial rhythmic changes in the Pacific. Since the early 1990s, a warmer Atlantic due to the positive phase of Atlantic multidecadal oscillation and global warming trend has provided more favourable background state for the Atlantic capacitor effect, giving rise to enhanced biennial variability in the Pacific that may increase the occurrence frequency of severe natural hazard events.

Information content in Iris spectra. [Infrared Interferometer Spectrometer of Nimbus 4 satellite

NASA Technical Reports Server (NTRS)

Price, J. C.

1975-01-01

Spectra from the satellite instrument Iris (infrared interferometer spectrometer) were examined to find the number of independent variables needed to describe the broad-band high-resolution spectral data. The radiated power in the atmospheric window from 771 to 981 per cm was the first parameter chosen for fitting observed spectra. At succeeding levels of analysis, the residual variability (observed spectrum minus best-fit spectrum) in an ensemble of observations was partitioned into spectral eigenvectors. The eigenvector describing the largest fraction of this variability was examined for a strong spectral signature; the power in the corresponding spectral band was then used as the next fitting parameter. The measured power in nine spectral intervals, when it was inserted in the spectral-fitting functions, was adequate to describe most spectra to within the noise level of Iris. Considerations of relative signal strength and scales of atmospheric variability suggest a combination sounder (multichannel, broad field of view) scanner (window channel, small field of view) as an efficient observing instrument.

Emotion dysregulation in alexithymia: Startle reactivity to fearful affective imagery and its relation to heart rate variability.

PubMed

Panayiotou, Georgia; Constantinou, Elena

2017-09-01

Alexithymia is associated with deficiencies in recognizing and expressing emotions and impaired emotion regulation, though few studies have verified the latter assertion using objective measures. This study examined startle reflex modulation by fearful imagery and its associations with heart rate variability in alexithymia. Fifty-four adults (27 alexithymic) imagined previously normed fear scripts. Startle responses were assessed during baseline, first exposure, and reexposure. During first exposure, participants, in separate trials, engaged in either shallow or deep emotion processing, giving emphasis on descriptive or affective aspects of imagery, respectively. Resting heart rate variability was assessed during 2 min of rest prior to the experiment, with high alexithymic participants demonstrating significantly higher LF/HF (low frequency/high frequency) ratio than controls. Deep processing was associated with nonsignificantly larger and faster startle responses at first exposure for alexithymic participants. Lower LF/HF ratio, reflecting higher parasympathetic cardiac activity, predicted greater startle amplitude habituation for alexithymia but lower habituation for controls. Results suggest that, when exposed to prolonged threat, alexithymics may adjust poorly, showing a smaller initial defensive response but slower habituation. This pattern seems related to their low emotion regulation ability as indexed by heart rate variability. © 2017 Society for Psychophysiological Research.

Long-Term Monitoring of Molecular Masers in IRAS 18566+0408

NASA Astrophysics Data System (ADS)

Halbe, Daniel Michael; Araya, Esteban; Hofner, Peter; Linz, Hendrik; Olmi, Luca; Kurtz, Stan

2016-01-01

We report results of a long-term monitoring study of 6 cm formaldehyde (H2CO),6.035 GHz hydroxyl (OH), and 6.7 GHz methanol (CH3OH) masers in the young high-mass protostellar object IRAS 18566+0408 (G37.55+0.20). This is the only high-mass star forming region where correlated variability of three different maser species has been reported. The observations were conducted with the 305m Arecibo Radio Telescope and the Very Large Array. Together with data from the literature, we present H2CO flux density measurements from 2002 to 2014, CH3OH data from 2006 to 2015, and OH observations from 2008 to 2015. Our extended monitoring observations of the H2CO maser agree with quasi-periodic variability and exponential flux density decrease during the quiescent and flare states as proposed by Araya and collaborators in 2010. We also confirm the occurrence of 6.035 GHz OH flares and a time delay with respect to the H2CO flares (first reported by Al-Marzouk and collaborators in 2012). An analysis of the variability behavior of different CH3OH velocity components and the H2CO maser suggests that multiple variability mechanisms may be responsible for the CH3OH flux density changes.

Can fitness and movement quality prevent back injury in elite task force police officers? A 5-year longitudinal study.

PubMed

McGill, Stuart; Frost, David; Lam, Thomas; Finlay, Tim; Darby, Kevin; Cannon, Jordan

2015-01-01

Elite police work has bursts of intense physically demanding work requiring high levels of fitness, or capacity, and movement competency; which are assumed to increase one's injury resilience. The purpose of this study was to follow members of an elite police force (N = 53) to test whether back injuries (N = 14) could be predicted from measures of fitness and movement quality. Measures of torso endurance, relative and absolute strength, hip ROM and movement quality using the Functional Movement Screen(TM) and other dynamic movement tests were obtained from every officer at baseline. When variables were grouped and considered holistically, rather than individually, back injury could be predicted. Seven variables best predicted those who would suffer a back injury (64% sensitivity and 95% specificity for an overall concordance of 87%). Overall, the ability to predict back injury was not high, suggesting that there is more complexity to this relationship than is explained with the variables tested here. Practitioner Summary: Members of elite police forces have exposure to intense physically demanding work. Increased levels of fitness and movement competency have been assumed to increase injury resilience. However, complexity in the interactions between exposure, movement competency, training, fitness and injury may occlude the true relationship between these variables.

Consistency of kinematic and kinetic patterns during a prolonged spell of cricket fast bowling: an exploratory laboratory study.

PubMed

Schaefer, Andrew; O'dwyer, Nicholas; Ferdinands, René E D; Edwards, Suzi

2018-03-01

Due to the high incidence of lumbar spine injury in fast bowlers, international cricket organisations advocate limits on workload for bowlers under 19 years of age in training/matches. The purpose of this study was to determine whether significant changes in either fast bowling technique or movement variability could be detected throughout a 10-over bowling spell that exceeded the recommended limit. Twenty-five junior male fast bowlers bowled at competition pace while three-dimensional kinematic and kinetic data were collected for the leading leg, trunk and bowling arm. Separate analyses for the mean and within-participant standard deviation of each variable were performed using repeated measures factorial analyses of variance and computation of effect sizes. No substantial changes were observed in mean values or variability of any kinematic, kinetic or performance variables, which instead revealed a high degree of consistency in kinematic and kinetic patterns. Therefore, the suggestion that exceeding the workload limit per spell causes technique- and loading-related changes associated with lumbar injury risk is not valid and cannot be used to justify the restriction of bowling workload. For injury prevention, the focus instead should be on the long-term effect of repeated spells and on the fast bowling technique itself.

RAPID OPTICAL VARIABILITY IN BLAZAR S5 0716+71 DURING 2010 MARCH

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

Chandra, S.; Baliyan, K. S.; Ganesh, S.

We report rapid optical variability for the blazar S5 0716+71 during 2010 March 8-10 and 19-20 in the CCD observations made from Mt. Abu Infrared Observatory. The light curves are constructed for a duration longer than 3 hr each night, with very high temporal resolution ({approx}45 s in the R band). During 2010 March 8, the source smoothly decayed by about 0.15 mag in 2.88 hr, apart from a fast flicker lasting about 30 minutes. S5 0716+71 brightened during March 9 and 10, showing high activity, while it was relatively faint (>14 mag in the R band) albeit variable duringmore » March 19-20. During March 9 and 10, rapid flickers in the intensity modulated the long-term intra-night ({approx}3 hr) variations. The present observations suggest that the blazar S5 0716+71 showed night-to-night and intra-night variability at various timescales with a 100% duty cycle for variation along with microvariability at significant levels. On a night-to-night basis, the source exhibits mild bluer-when-brighter nature. The interaction of shocks with local inhomogeneities in the jet appears to cause intra-night variations, while microvariations could be due to small-scale perturbations intrinsic to the jet.« less

Variable intertidal temperature explains why disease endangers black abalone

USGS Publications Warehouse

Ben-Horin, Tal; Lenihan, Hunter S.; Lafferty, Kevin D.

2013-01-01

Epidemiological theory suggests that pathogens will not cause host extinctions because agents of disease should fade out when the host population is driven below a threshold density. Nevertheless, infectious diseases have threatened species with extinction on local scales by maintaining high incidence and the ability to spread efficiently even as host populations decline. Intertidal black abalone (Haliotis cracherodii), but not other abalone species, went extinct locally throughout much of southern California following the emergence of a Rickettsiales-like pathogen in the mid-1980s. The rickettsial disease, a condition known as withering syndrome (WS), and associated mortality occur at elevated water temperatures. We measured abalone body temperatures in the field and experimentally manipulated intertidal environmental conditions in the laboratory, testing the influence of mean temperature and daily temperature variability on key epizootiological processes of WS. Daily temperature variability increased the susceptibility of black abalone to infection, but disease expression occurred only at warm water temperatures and was independent of temperature variability. These results imply that high thermal variation of the marine intertidal zone allows the pathogen to readily infect black abalone, but infected individuals remain asymptomatic until water temperatures periodically exceed thresholds modulating WS. Mass mortalities can therefore occur before pathogen transmission is limited by density-dependent factors.

Controls on the East Asian monsoon during the last glacial cycle, based on comparison between Hulu Cave and polar ice-core records

NASA Astrophysics Data System (ADS)

Rohling, E. J.; Liu, Q. S.; Roberts, A. P.; Stanford, J. D.; Rasmussen, S. O.; Langen, P. L.; Siddall, M.

2009-12-01

Previous studies have suggested a sound chronological correlation between the Hulu Cave record (East Asian monsoon) and Greenland ice-core records, which implies a dominant control of northern hemisphere climate processes on monsoon intensity. We present an objective, straightforward statistical evaluation that challenges this generally accepted paradigm for sub-orbital variability. We propose a more flexible, global interpretation, which takes into account a broad range of variability in the signal structures in the Hulu Cave and polar ice-core records, rather than a limited number of major transitions. Our analysis employs the layer-counted Greenland Ice-Core Chronology 2005 (GICC05), which was developed for Greenland records and has since been applied - via methane synchronisation - to the high-resolution δ 18O ice series from EPICA Dronning Maud Land (EDML). The GICC05 chronology allows these ice-core records to be compared to the U-Th dated Hulu Cave record within relatively narrow (˜3%) bounds of age uncertainty. Following previous suggestions, our proposed interpretation suggests that the East Asian monsoon is influenced by a combination of northern hemisphere 'pull' (which is more intense during boreal warm periods), and southern hemisphere 'push' (which is more intense monsoon during austral cold periods). Our analysis strongly suggests a dominant control on millennial-scale monsoon variability by southern hemisphere climate changes during glacial times when the monsoon is weak overall, and control by northern hemisphere climate changes during deglacial and interglacial times when the monsoon is strong. The deduced temporally variable relationship with southern hemisphere climate records offers a statistically more plausible reason for the apparent coincidence of major East Asian monsoon transitions with northern hemisphere (Dansgaard-Oeschger, DO) climate events during glacial times, than the traditional a priori interpretation of strict northern hemisphere control.

High variability of dung beetle diversity patterns at four mountains of the Trans-Mexican Volcanic Belt

PubMed Central

Arriaga-Jiménez, Alfonsina; Halffter, Gonzalo

2018-01-01

Insect diversity patterns of high mountain ecosystems remain poorly studied in the tropics. Sampling dung beetles of the subfamilies Aphodiinae, Scarabaeinae, and Geotrupinae was carried out at four volcanoes in the Trans-Mexican Volcanic Belt (TMVB) in the Mexican transition zone at 2,700 and 3,400 MASL, and on the windward and leeward sides. Sampling units represented a forest–shrubland–pasture (FSP) mosaic typical of this mountain region. A total of 3,430 individuals of 29 dung beetle species were collected. Diversity, abundance and compositional similarity (CS) displayed a high variability at all scales; elevation, cardinal direction, or FSP mosaics did not show any patterns of higher or lower values of those measures. The four mountains were different regarding dispersion patterns and taxonomic groups, both for species and individuals. Onthophagus chevrolati dominated all four mountains with an overall relative abundance of 63%. CS was not related to distance among mountains, but when O. chevrolati was excluded from the analysis, CS values based on species abundance decreased with increasing distance. Speciation, dispersion, and environmental instability are suggested as the main drivers of high mountain diversity patterns, acting together at different spatial and temporal scales. Three species new to science were collected (>10% of all species sampled). These discoveries may indicate that speciation rate is high among these volcanoes—a hypothesis that is also supported by the elevated number of collected species with a restricted montane distribution. Dispersion is an important factor in driving species composition, although naturally limited between high mountains; horizontal colonization events at different time scales may best explain the observed species composition in the TMVB, complemented by vertical colonization events to a lesser extent. Environmental instability may be the main factor causing the high variability of diversity and abundance patterns found during sampling. Together, we interpret these results as indicating that species richness and composition in the high mountains of the TMVB may be driven by biogeographical history while variability in diversity is determined by ecological factors. We argue that current conservation strategies do not focus sufficiently on protecting high mountain fauna, and that there is a need for developing and applying new conservation concepts that take into account the high spatial and temporal variability of this system. PMID:29507842

Temporal variability of air-sea CO2 exchange in a low-emission estuary

NASA Astrophysics Data System (ADS)

Mørk, Eva Thorborg; Sejr, Mikael Kristian; Stæhr, Peter Anton; Sørensen, Lise Lotte

2016-07-01

There is the need for further study of whether global estimates of air-sea CO2 exchange in estuarine systems capture the relevant temporal variability and, as such, the temporal variability of bulk parameterized and directly measured CO2 fluxes was investigated in the Danish estuary, Roskilde Fjord. The air-sea CO2 fluxes showed large temporal variability across seasons and between days and that more than 30% of the net CO2 emission in 2013 was a result of two large fall and winter storms. The diurnal variability of ΔpCO2 was up to 400 during summer changing the estuary from a source to a sink of CO2 within the day. Across seasons the system was suggested to change from a sink of atmospheric CO2 during spring to near neutral during summer and later to a source of atmospheric CO2 during fall. Results indicated that Roskilde Fjord was an annual low-emission estuary, with an estimated bulk parameterized release of 3.9 ± 8.7 mol CO2 m-2 y-1 during 2012-2013. It was suggested that the production-respiration balance leading to the low annual emission in Roskilde Fjord, was caused by the shallow depth, long residence time and high water quality in the estuary. In the data analysis the eddy covariance CO2 flux samples were filtered according to the H2Osbnd CO2 cross-sensitivity assessment suggested by Landwehr et al. (2014). This filtering reduced episodes of contradicting directions between measured and bulk parameterized air-sea CO2 exchanges and changed the net air-sea CO2 exchange from an uptake to a release. The CO2 gas transfer velocity was calculated from directly measured CO2 fluxes and ΔpCO2 and agreed to previous observations and parameterizations.

Production of single cell protein from cellulose wastes

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

Humphrey, A.E.; Moreira, A.; Armiger, W.

1977-01-01

Experiments made with a thermophilic Actinomyces that utilizes cellulose for growth are summarized. The organism, identified as a Thermoactinomyces sp., is a highly filamentous fungi. Although initial work was done with feedlot wastes, the variability of the data made it necessary to work on a uniform cellulose substrate Avicel. A probable mechanism of cellulose degradation by this fungi is suggested. Preliminary results are encouraging, but high growth rate must be maintained if a high cell yield is to be achieved. Both glucose and oxygen-limited growth were encountered; it is not known if these were coincidental or not. (JSR)

Juniperus phoenicea var. turbinata (Guss.) Parl. Leaf Essential Oil Variability in the Balkans.

PubMed

Rajčević, Nemanja F; Labus, Marina G; Dodoš, Tanja Z; Novaković, Jelica J; Marin, Petar D

2018-06-15

In the present work leaf essential oil from 97 individuals of Juniperus phoenicea var. turbinata (GUSS.) PARL. from the Balkan Peninsula was analysed. The essential oil was dominated by monoterpene hydrocarbons (45.5 - 71.8%), of which α-pinene was the most abundant in almost all of the samples (38.2 - 55.8%). Several other monoterpenes and sesquiterpenes were also present in relatively high abundances in samples such as myrcene, δ-3-carene, ß-phellandrene, α-terpinyl acetate, (E)-caryophyllene and germacrene D. Multivariate statistical analysis suggested the existence of three possible chemotypes based on the abundance of the four components. Even though the intrapopulation variability was high, discriminant analysis (DA) was able to separate populations. DA showed high separation between western and eastern populations but also grouped geographically closer populations along the west Balkan shoreline. The potential influence of the climate on the composition of the essential oil was also studied. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Proposal and Development of a High Voltage Variable Frequency Alternating Current Power System for Hybrid Electric Aircraft

NASA Technical Reports Server (NTRS)

Sadey, David J.; Taylor, Linda M.; Beach, Raymond F.

2017-01-01

The development of ultra-efficient commercial vehicles and the transition to low-carbon emission propulsion are seen as strategic thrust paths within NASA Aeronautics. A critical enabler to these paths comes in the form of hybrid electric propulsion systems. For megawatt-class systems, the best power system topology for these hybrid electric propulsion systems is debatable. Current proposals within NASA and the Aero community suggest using a combination of alternating current (AC) and direct current (DC) for power generation, transmission, and distribution. This paper proposes an alternative to the current thought model through the use of a primarily high voltage AC power system, supported by the Convergent Aeronautics Solutions (CAS) Project. This system relies heavily on the use of doubly-fed induction machines (DFIMs), which provide high power densities, minimal power conversion, and variable speed operation. The paper presents background on the activity along with the system architecture, development status, and preliminary results.

The isotopic and chemical evolution of Mount St. Helens

USGS Publications Warehouse

Halliday, A.N.; Fallick, A.E.; Dickin, A.P.; Mackenzie, A.B.; Stephens, W.E.; Hildreth, W.

1983-01-01

Isotopic and major and trace element analysis of nine samples of eruptive products spanning the history of the Mt. St. Helens volcano suggest three different episodes; (1) 40,000-2500 years ago: eruptions of dacite with ??{lunate}Nd = +5, ??{lunate}Sr = -10, variable ??18O, 206Pb/204Pb ??? 18.76, Ca/Sr ??? 60, Rb/Ba ??? 0.1, La/Yb ??? 18, (2) 2500-1000 years ago: eruptions of basalt, andesite and dacite with ??{lunate}Nd = +4 to +8, ??{lunate}Sr = -7 to -22, variable ??18O (thought to represent melting of differing mantle-crust reservoirs), 206Pb/204Pb = 18.81-18.87, variable Ca/Sr, Rb/Ba, La/Yb and high Zr, (3) 1000 years ago to present day: eruptions of andesite and dacite with ??{lunate}Nd = +6, ??{lunate}Sr = -13, ??18O ???6???, variable 206Pb/204Pb, Ca/Sr ??? 77, Rb/Ba = 0.1, La/Yb ??? 11. None of the products exhibit Eu anomalies and all are LREE enriched. There is a strong correlation between 87Sr/86Sr and differentiation indices. These data are interpreted in terms of a mantle heat source melting young crust bearing zircon and garnet, but not feldspar, followed by intrusion of this crustal reservoir by mantle-derived magma which caused further crustal melting and contaminated the crustal magma system with mafic components. Since 1000 years ago all the eruptions have been from the same reservoir which has displayed a much more gradual re-equilibration of Pb isotopic compositions than other components suggesting that Pb is being transported via a fluid phase. The Nd and Sr isotopic compositions lie along the mantle array and suggest that the mantle underneath Mt. St. Helens is not as depleted as MORB sources. There is no indication of seawater involvement in the source region. ?? 1983.

Influence of variable water depth and turbidity on microalgae production in a shallow estuarine lake system - A modelling study

NASA Astrophysics Data System (ADS)

Tirok, Katrin; Scharler, Ursula M.

2014-06-01

Strongly varying water levels and turbidities are typical characteristics of the large shallow estuarine lake system of St. Lucia, one of the largest on the African continent. This theoretical study investigated the combined effects of variable water depth and turbidity on seasonal pelagic and benthic microalgae production using a mathematical model, in order to ascertain productivity levels during variable and extreme conditions. Simulated pelagic and benthic net production varied between 0.3 and 180 g C m-2 year-1 and 0 and 220 g C m-2 year-1, respectively, dependent on depth, turbidity, and variability in turbidity. Although not surprising production and biomass decreased with increasing turbidity and depth. A high variability in turbidity, i.e. an alteration of calm and windy days, could reduce or enhance the seasonal pelagic and benthic production by more than 30% compared to a low variability. The day-to-day variability in wind-induced turbidity therefore influences production in the long term. On the other hand, varying water depth within a year did not significantly influence the seasonal production for turbidities representative of Lake St. Lucia. Reduced lake area and volume as observed during dry periods in Lake St. Lucia did not reduce primary production of the entire system since desiccation resulted in lower water depth and thus increased light availability. This agrees with field observations suggesting little light limitation and high areal microalgal biomass during a period with below average rainfall (2005-2011). Thus, microalgae potentially fulfil their function in the lake food-web even under extreme drought conditions. We believe that these results are of general interest to shallow aquatic ecosystems that are sensitive to drought periods due to either human or natural causes.

Assessing Local Knowledge Use in Agroforestry Management with Cognitive Maps

NASA Astrophysics Data System (ADS)

Isaac, Marney E.; Dawoe, Evans; Sieciechowicz, Krystyna

2009-06-01

Small-holder farmers often develop adaptable agroforestry management techniques to improve and diversify crop production. In the cocoa growing region of Ghana, local knowledge on such farm management holds a noteworthy role in the overall farm development. The documentation and analysis of such knowledge use in cocoa agroforests may afford an applicable framework to determine mechanisms driving farmer preference and indicators in farm management. This study employed 12 in-depth farmer interviews regarding variables in farm management as a unit of analysis and utilized cognitive mapping as a qualitative method of analysis. Our objectives were (1) to illustrate and describe agroforestry management variables and associated farm practices, (2) to determine the scope of decision making of individual farmers, and (3) to investigate the suitability of cognitive mapping as a tool for assessing local knowledge use. Results from the cognitive maps revealed an average of 16 ± 3 variables and 19 ± 3 links between management variables in the farmer cognitive maps. Farmer use of advantageous ecological processes was highly central to farm management (48% of all variables), particularly manipulation of organic matter, shade and food crop establishment, and maintenance of a tree stratum as the most common, highly linked variables. Over 85% of variables included bidirectional arrows, interpreted as farm management practices dominated by controllable factors, insofar as farmers indicated an ability to alter most farm characteristics. Local knowledge use on cocoa production revealed detailed indicators for site evaluation, thus affecting farm preparation and management. Our findings suggest that amid multisourced information under conditions of uncertainty, strategies for adaptable agroforestry management should integrate existing and localized management frameworks and that cognitive mapping provides a tool-based approach to advance such a management support system.

Importance of physical and hydraulic characteristics to unionid mussels: A retrospective analysis in a reach of large river

USGS Publications Warehouse

Zigler, S.J.; Newton, T.J.; Steuer, J.J.; Bartsch, M.R.; Sauer, J.S.

2008-01-01

Interest in understanding physical and hydraulic factors that might drive distribution and abundance of freshwater mussels has been increasing due to their decline throughout North America. We assessed whether the spatial distribution of unionid mussels could be predicted from physical and hydraulic variables in a reach of the Upper Mississippi River. Classification and regression tree (CART) models were constructed using mussel data compiled from various sources and explanatory variables derived from GIS coverages. Prediction success of CART models for presence-absence of mussels ranged from 71 to 76% across three gears (brail, sled-dredge, and dive-quadrat) and 51% of the deviance in abundance. Models were largely driven by shear stress and substrate stability variables, but interactions with simple physical variables, especially slope, were also important. Geospatial models, which were based on tree model results, predicted few mussels in poorly connected backwater areas (e.g., floodplain lakes) and the navigation channel, whereas main channel border areas with high geomorphic complexity (e.g., river bends, islands, side channel entrances) and small side channels were typically favorable to mussels. Moreover, bootstrap aggregation of discharge-specific regression tree models of dive-quadrat data indicated that variables measured at low discharge were about 25% more predictive (PMSE = 14.8) than variables measured at median discharge (PMSE = 20.4) with high discharge (PMSE = 17.1) variables intermediate. This result suggests that episodic events such as droughts and floods were important in structuring mussel distributions. Although the substantial mussel and ancillary data in our study reach is unusual, our approach to develop exploratory statistical and geospatial models should be useful even when data are more limited. ?? 2007 Springer Science+Business Media B.V.

Assessing local knowledge use in agroforestry management with cognitive maps.

PubMed

Isaac, Marney E; Dawoe, Evans; Sieciechowicz, Krystyna

2009-06-01

Small-holder farmers often develop adaptable agroforestry management techniques to improve and diversify crop production. In the cocoa growing region of Ghana, local knowledge on such farm management holds a noteworthy role in the overall farm development. The documentation and analysis of such knowledge use in cocoa agroforests may afford an applicable framework to determine mechanisms driving farmer preference and indicators in farm management. This study employed 12 in-depth farmer interviews regarding variables in farm management as a unit of analysis and utilized cognitive mapping as a qualitative method of analysis. Our objectives were (1) to illustrate and describe agroforestry management variables and associated farm practices, (2) to determine the scope of decision making of individual farmers, and (3) to investigate the suitability of cognitive mapping as a tool for assessing local knowledge use. Results from the cognitive maps revealed an average of 16 +/- 3 variables and 19 +/- 3 links between management variables in the farmer cognitive maps. Farmer use of advantageous ecological processes was highly central to farm management (48% of all variables), particularly manipulation of organic matter, shade and food crop establishment, and maintenance of a tree stratum as the most common, highly linked variables. Over 85% of variables included bidirectional arrows, interpreted as farm management practices dominated by controllable factors, insofar as farmers indicated an ability to alter most farm characteristics. Local knowledge use on cocoa production revealed detailed indicators for site evaluation, thus affecting farm preparation and management. Our findings suggest that amid multisourced information under conditions of uncertainty, strategies for adaptable agroforestry management should integrate existing and localized management frameworks and that cognitive mapping provides a tool-based approach to advance such a management support system.

Implications of Supermarket Access, Neighborhood Walkability, and Poverty Rates for Diabetes Risk in an Employee Population

PubMed Central

Herrick, Cynthia J.; Yount, Byron W.; Eyler, Amy A.

2016-01-01

Objective Diabetes is a growing public health problem, and the environment in which people live and work may affect diabetes risk. The goal of this study was to examine the association between multiple aspects of environment and diabetes risk in an employee population. Design This was a retrospective cross-sectional analysis. Home environment variables were derived using employee zip code. Descriptive statistics were run on all individual and zip code level variables, stratified by diabetes risk and worksite. A multivariable logistic regression analysis was then conducted to determine the strongest associations with diabetes risk. Setting Data was collected from employee health fairs in a Midwestern health system 2009–2012. Subjects The dataset contains 25,227 unique individuals across four years of data. From this group, using an individual’s first entry into the database, 15,522 individuals had complete data for analysis. Results The prevalence of high diabetes risk in this population was 2.3%. There was significant variability in individual and zip code level variables across worksites. From the multivariable analysis, living in a zip code with higher percent poverty and higher walk score was positively associated with high diabetes risk, while living in a zip code with higher supermarket density was associated with a reduction in high diabetes risk. Conclusions Our study underscores the important relationship between poverty, home neighborhood environment, and diabetes risk, even in a relatively healthy employed population, and suggests a role for the employer in promoting health. PMID:26638995

Implications of supermarket access, neighbourhood walkability and poverty rates for diabetes risk in an employee population.

PubMed

Herrick, Cynthia J; Yount, Byron W; Eyler, Amy A

2016-08-01

Diabetes is a growing public health problem, and the environment in which people live and work may affect diabetes risk. The goal of the present study was to examine the association between multiple aspects of environment and diabetes risk in an employee population. This was a retrospective cross-sectional analysis. Home environment variables were derived using employees' zip code. Descriptive statistics were run on all individual- and zip-code-level variables, stratified by diabetes risk and worksite. A multivariable logistic regression analysis was then conducted to determine the strongest associations with diabetes risk. Data were collected from employee health fairs in a Midwestern health system, 2009-2012. The data set contains 25 227 unique individuals across four years of data. From this group, using an individual's first entry into the database, 15 522 individuals had complete data for analysis. The prevalence of high diabetes risk in this population was 2·3 %. There was significant variability in individual- and zip-code-level variables across worksites. From the multivariable analysis, living in a zip code with higher percentage of poverty and higher walk score was positively associated with high diabetes risk, while living in a zip code with higher supermarket density was associated with a reduction in high diabetes risk. Our study underscores the important relationship between poverty, home neighbourhood environment and diabetes risk, even in a relatively healthy employed population, and suggests a role for the employer in promoting health.

Extraversion and cardiovascular responses to recurrent social stress: Effect of stress intensity.

PubMed

Lü, Wei; Xing, Wanying; Hughes, Brian M; Wang, Zhenhong

2017-10-28

The present study sought to establish whether the effects of extraversion on cardiovascular responses to recurrent social stress are contingent on stress intensity. A 2×5×1 mixed-factorial experiment was conducted, with social stress intensity as a between-subject variable, study phase as a within-subject variable, extraversion as a continuous independent variable, and cardiovascular parameter (HR, SBP, DBP, or RSA) as a dependent variable. Extraversion (NEO-FFI), subjective stress, and physiological stress were measured in 166 undergraduate students randomly assigned to undergo moderate (n=82) or high-intensity (n=84) social stress (a public speaking task with different levels of social evaluation). All participants underwent continuous physiological monitoring while facing two consecutive stress exposures distributed across five laboratory phases: baseline, stress exposure 1, post-stress 1, stress exposure 2, post-stress 2. Results indicated that under moderate-intensity social stress, participants higher on extraversion exhibited lesser HR reactivity to stress than participants lower on extraversion, while under high-intensity social stress, they exhibited greater HR, SBP, DBP and RSA reactivity. Under both moderate- and high-intensity social stress, participants higher on extraversion exhibited pronounced SBP and DBP response adaptation to repeated stress, and showed either better degree of HR recovery or greater amount of SBP and DBP recovery after stress. These findings suggest that individuals higher on extraversion exhibit physiological flexibility to cope with social challenges and benefit from adaptive cardiovascular responses. Copyright © 2017 Elsevier B.V. All rights reserved.

SPITZER OBSERVATIONS OF LONG-TERM INFRARED VARIABILITY AMONG YOUNG STELLAR OBJECTS IN CHAMAELEON I

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

Flaherty, Kevin M.; Herbst, William; DeMarchi, Lindsay

Infrared variability is common among young stellar objects, with surveys finding daily to weekly fluctuations of a few tenths of a magnitude. Space-based observations can produce highly sampled infrared light curves, but are often limited to total baselines of about 1 month due to the orientation of the spacecraft. Here we present observations of the Chameleon I cluster, whose low declination makes it observable by the Spitzer Space Telescope over a 200-day period. We observe 30 young stellar objects with a daily cadence to better sample variability on timescales of months. We find that such variability is common, occurring inmore » ∼80% of the detected cluster members. The change in [3.6]–[4.5] color over 200 days for many of the sources falls between that expected for extinction and fluctuations in disk emission. With our high cadence and long baseline we can derive power spectral density curves covering two orders of magnitude in frequency and find significant power at low frequencies, up to the boundaries of our 200-day survey. Such long timescales are difficult to explain with variations driven by the interaction between the disk and stellar magnetic field, which has a dynamical timescale of days to weeks. The most likely explanation is either structural or temperature fluctuations spread throughout the inner ∼0.5 au of the disk, suggesting that the intrinsic dust structure is highly dynamic.« less

Determinants of Fast Food Consumption among Iranian High School Students Based on Planned Behavior Theory

PubMed Central

Sharifirad, Gholamreza; Yarmohammadi, Parastoo; Azadbakht, Leila; Morowatisharifabad, Mohammad Ali; Hassanzadeh, Akbar

2013-01-01

Objective. This study was conducted to identify some factors (beliefs and norms) which are related to fast food consumption among high school students in Isfahan, Iran. We used the framework of the theory planned behavior (TPB) to predict this behavior. Subjects & Methods. Cross-sectional data were available from high school students (n = 521) who were recruited by cluster randomized sampling. All of the students completed a questionnaire assessing variables of standard TPB model including attitude, subjective norms, perceived behavior control (PBC), and the additional variables past behavior, actual behavior control (ABC). Results. The TPB variables explained 25.7% of the variance in intentions with positive attitude as the strongest (β = 0.31, P < 0.001) and subjective norms as the weakest (β = 0.29, P < 0.001) determinant. Concurrently, intentions accounted for 6% of the variance for fast food consumption. Past behavior and ABC accounted for an additional amount of 20.4% of the variance in fast food consumption. Conclusion. Overall, the present study suggests that the TPB model is useful in predicting related beliefs and norms to the fast food consumption among adolescents. Subjective norms in TPB model and past behavior in TPB model with additional variables (past behavior and actual behavior control) were the most powerful predictors of fast food consumption. Therefore, TPB model may be a useful framework for planning intervention programs to reduce fast food consumption by students. PMID:23936635

Health Impacts of the Built Environment: Within-Urban Variability in Physical Inactivity, Air Pollution, and Ischemic Heart Disease Mortality

PubMed Central

Hankey, Steve; Brauer, Michael

2011-01-01

Background: Physical inactivity and exposure to air pollution are important risk factors for death and disease globally. The built environment may influence exposures to these risk factors in different ways and thus differentially affect the health of urban populations. Objective: We investigated the built environment’s association with air pollution and physical inactivity, and estimated attributable health risks. Methods: We used a regional travel survey to estimate within-urban variability in physical inactivity and home-based air pollution exposure [particulate matter with aerodynamic diameter ≤ 2.5 μm (PM2.5), nitrogen oxides (NOx), and ozone (O3)] for 30,007 individuals in southern California. We then estimated the resulting risk for ischemic heart disease (IHD) using literature-derived dose–response values. Using a cross-sectional approach, we compared estimated IHD mortality risks among neighborhoods based on “walkability” scores. Results: The proportion of physically active individuals was higher in high- versus low-walkability neighborhoods (24.9% vs. 12.5%); however, only a small proportion of the population was physically active, and between-neighborhood variability in estimated IHD mortality attributable to physical inactivity was modest (7 fewer IHD deaths/100,000/year in high- vs. low-walkability neighborhoods). Between-neighborhood differences in estimated IHD mortality from air pollution were comparable in magnitude (9 more IHD deaths/100,000/year for PM2.5 and 3 fewer IHD deaths for O3 in high- vs. low-walkability neighborhoods), suggesting that population health benefits from increased physical activity in high-walkability neighborhoods may be offset by adverse effects of air pollution exposure. Policy implications: Currently, planning efforts mainly focus on increasing physical activity through neighborhood design. Our results suggest that differences in population health impacts among neighborhoods are similar in magnitude for air pollution and physical activity. Thus, physical activity and exposure to air pollution are critical aspects of planning for cleaner, health-promoting cities. PMID:22004949

Health impacts of the built environment: within-urban variability in physical inactivity, air pollution, and ischemic heart disease mortality.

PubMed

Hankey, Steve; Marshall, Julian D; Brauer, Michael

2012-02-01

Physical inactivity and exposure to air pollution are important risk factors for death and disease globally. The built environment may influence exposures to these risk factors in different ways and thus differentially affect the health of urban populations. We investigated the built environment's association with air pollution and physical inactivity, and estimated attributable health risks. We used a regional travel survey to estimate within-urban variability in physical inactivity and home-based air pollution exposure [particulate matter with aerodynamic diameter ≤ 2.5 μm (PM2.5), nitrogen oxides (NOx), and ozone (O3)] for 30,007 individuals in southern California. We then estimated the resulting risk for ischemic heart disease (IHD) using literature-derived dose-response values. Using a cross-sectional approach, we compared estimated IHD mortality risks among neighborhoods based on "walkability" scores. The proportion of physically active individuals was higher in high- versus low-walkability neighborhoods (24.9% vs. 12.5%); however, only a small proportion of the population was physically active, and between-neighborhood variability in estimated IHD mortality attributable to physical inactivity was modest (7 fewer IHD deaths/100,000/year in high- vs. low-walkability neighborhoods). Between-neighborhood differences in estimated IHD mortality from air pollution were comparable in magnitude (9 more IHD deaths/100,000/year for PM2.5 and 3 fewer IHD deaths for O3 in high- vs. low-walkability neighborhoods), suggesting that population health benefits from increased physical activity in high-walkability neighborhoods may be offset by adverse effects of air pollution exposure. Currently, planning efforts mainly focus on increasing physical activity through neighborhood design. Our results suggest that differences in population health impacts among neighborhoods are similar in magnitude for air pollution and physical activity. Thus, physical activity and exposure to air pollution are critical aspects of planning for cleaner, health-promoting cities.

Effects of whole body heating on dynamic baroreflex regulation of heart rate in humans

NASA Technical Reports Server (NTRS)

Crandall, C. G.; Zhang, R.; Levine, B. D.

2000-01-01

The purpose of this project was to identify whether dynamic baroreflex regulation of heart rate (HR) is altered during whole body heating. In 14 subjects, dynamic baroreflex regulation of HR was assessed using transfer function analysis. In normothermic and heat-stressed conditions, each subject breathed at a fixed rate (0. 25 Hz) while beat-by-beat HR and systolic blood pressure (SBP) were obtained. Whole body heating significantly increased sublingual temperature, HR, and forearm skin blood flow. Spectral analysis of HR and SBP revealed that the heat stress significantly reduced HR and SBP variability within the high-frequency range (0.2-0.3 Hz), reduced SBP variability within the low-frequency range (0.03-0.15 Hz), and increased the ratio of low- to high-frequency HR variability (all P < 0.01). Transfer function gain analysis showed that the heat stress reduced dynamic baroreflex regulation of HR within the high-frequency range (from 1.04 +/- 0.06 to 0.54 +/- 0.6 beats. min(-1). mmHg(-1); P < 0.001) without significantly affecting the gain in the low-frequency range (P = 0.63). These data suggest that whole body heating reduced high-frequency dynamic baroreflex regulation of HR associated with spontaneous changes in blood pressure. Reduced vagal baroreflex regulation of HR may contribute to reduced orthostatic tolerance known to occur in humans during heat stress.

Biomechanical analysis of the jump shot in basketball.

PubMed

Struzik, Artur; Pietraszewski, Bogdan; Zawadzki, Jerzy

2014-09-29

Basketball players usually score points during the game using the jump shot. For this reason, the jump shot is considered to be the most important element of technique in basketball and requires a high level of performance. The aim of this study was to compare the biomechanical characteristics of the lower limbs during a jump shot without the ball and a countermovement jump without an arm swing. The differences between variables provide information about the potential that an athlete can utilise during a game when performing a jump shot. The study was conducted among 20 second-league basketball players by means of a Kistler force plate and the BTS SMART system for motion analysis. The variables measured included the take-off time, mean power, peak power, relative mean power, jump height, maximum landing force and calculated impact ratio. Surprisingly, more advantageous variables were found for the jump shot. This finding suggests a very high performance level in the jump shot in the studied group and a maximum utilisation of their motor abilities. Both types of jumps were characterised by high mean and peak power values and average heights. The high forces at landing, which result in considerable impact ratios, may have prompted the studied group to land softly. Use of the countermovement jump without an arm swing is recommended to assess and predict the progression of player's jumping ability.

Metacommunity ecology meets biogeography: effects of geographical region, spatial dynamics and environmental filtering on community structure in aquatic organisms.

PubMed

Heino, Jani; Soininen, Janne; Alahuhta, Janne; Lappalainen, Jyrki; Virtanen, Risto

2017-01-01

Metacommunity patterns and underlying processes in aquatic organisms have typically been studied within a drainage basin. We examined variation in the composition of six freshwater organismal groups across various drainage basins in Finland. We first modelled spatial structures within each drainage basin using Moran eigenvector maps. Second, we partitioned variation in community structure among three groups of predictors using constrained ordination: (1) local environmental variables, (2) spatial variables, and (3) dummy variable drainage basin identity. Third, we examined turnover and nestedness components of multiple-site beta diversity, and tested the best fit patterns of our datasets using the "elements of metacommunity structure" analysis. Our results showed that basin identity and local environmental variables were significant predictors of community structure, whereas within-basin spatial effects were typically negligible. In half of the organismal groups (diatoms, bryophytes, zooplankton), basin identity was a slightly better predictor of community structure than local environmental variables, whereas the opposite was true for the remaining three organismal groups (insects, macrophytes, fish). Both pure basin and local environmental fractions were, however, significant after accounting for the effects of the other predictor variable sets. All organismal groups exhibited high levels of beta diversity, which was mostly attributable to the turnover component. Our results showed consistent Clementsian-type metacommunity structures, suggesting that subgroups of species responded similarly to environmental factors or drainage basin limits. We conclude that aquatic communities across large scales are mostly determined by environmental and basin effects, which leads to high beta diversity and prevalence of Clementsian community types.

Association between climate variability and malaria epidemics in the East African highlands.

PubMed

Zhou, Guofa; Minakawa, Noboru; Githeko, Andrew K; Yan, Guiyun

2004-02-24

The causes of the recent reemergence of Plasmodium falciparum epidemic malaria in the East African highlands are controversial. Regional climate changes have been invoked as a major factor; however, assessing the impact of climate in malaria resurgence is difficult due to high spatial and temporal climate variability and the lack of long-term data series on malaria cases from different sites. Climate variability, defined as short-term fluctuations around the mean climate state, may be epidemiologically more relevant than mean temperature change, but its effects on malaria epidemics have not been rigorously examined. Here we used nonlinear mixed-regression model to investigate the association between autoregression (number of malaria outpatients during the previous time period), seasonality and climate variability, and the number of monthly malaria outpatients of the past 10-20 years in seven highland sites in East Africa. The model explained 65-81% of the variance in the number of monthly malaria outpatients. Nonlinear and synergistic effects of temperature and rainfall on the number of malaria outpatients were found in all seven sites. The net variance in the number of monthly malaria outpatients caused by autoregression and seasonality varied among sites and ranged from 18 to 63% (mean=38.6%), whereas 12-63% (mean=36.1%) of variance is attributed to climate variability. Our results suggest that there was a high spatial variation in the sensitivity of malaria outpatient number to climate fluctuations in the highlands, and that climate variability played an important role in initiating malaria epidemics in the East African highlands.

Environmental variability drives shifts in the foraging behaviour and reproductive success of an inshore seabird.

PubMed

Kowalczyk, Nicole D; Reina, Richard D; Preston, Tiana J; Chiaradia, André

2015-08-01

Marine animals forage in areas that aggregate prey to maximize their energy intake. However, these foraging 'hot spots' experience environmental variability, which can substantially alter prey availability. To survive and reproduce animals need to modify their foraging in response to these prey shifts. By monitoring their inter-annual foraging behaviours, we can understand which environmental variables affect their foraging efficiency, and can assess how they respond to environmental variability. Here, we monitored the foraging behaviour and isotopic niche of little penguins (Eudyptula minor), over 3 years (2008, 2011, and 2012) of climatic and prey variability within Port Phillip Bay, Australia. During drought (2008), penguins foraged in close proximity to the Yarra River outlet on a predominantly anchovy-based diet. In periods of heavy rainfall, when water depth in the largest tributary into the bay (Yarra River) was high, the total distance travelled, maximum distance travelled, distance to core-range, and size of core- and home-ranges of penguins increased significantly. This larger foraging range was associated with broad dietary diversity and high reproductive success. These results suggest the increased foraging range and dietary diversity of penguins were a means to maximize resource acquisition rather than a strategy to overcome local depletions in prey. Our results demonstrate the significance of the Yarra River in structuring predator-prey interactions in this enclosed bay, as well as the flexible foraging strategies of penguins in response to environmental variability. This plasticity is central to the survival of this small-ranging, resident seabird species.

Influence of muscle strength, physical activity and weight on bone mass in a population-based sample of 1004 elderly women.

PubMed

Gerdhem, P; Ringsberg, K A M; Akesson, K; Obrant, K J

2003-09-01

High physical activity level has been associated with high bone mass and low fracture risk and is therefore recommended to reduce fractures in old age. The aim of this study was to estimate the effect of potentially modifiable variables, such as physical activity, muscle strength, muscle mass and weight, on bone mass in elderly women. The influence of isometric thigh muscle strength, self-estimated activity level, body composition and weight on bone mineral density (dual energy X-ray absorptiometry; DXA) in total body, hip and spine was investigated. Subjects were 1004 women, all 75 years old, taking part in the Malmö Osteoporosis Prospective Risk Assessment (OPRA) study. Physical activity and muscle strength accounted for 1-6% of the variability in bone mass, whereas weight, and its closely associated variables lean mass and fat mass, to a much greater extent explained the bone mass variability. We found current body weight to be the variable with the most substantial influence on the total variability in bone mass (15-32% depending on skeletal site) in a forward stepwise regression model. Our findings suggest that in elderly women, the major fracture-preventive effect of physical activity is unlikely to be mediated through increased bone mass. Retaining or even increasing body weight is likely to be beneficial to the skeleton, but an excess body weight increase may have negative effects on health. Nevertheless, training in elderly women may have advantages by improving balance, co-ordination and mobility and therefore decreasing the risk of fractures.

Using In-Situ Optical Sensors to Understand the Biogeochemistry of Dissolved Organic Matter Across a Stream Network

NASA Astrophysics Data System (ADS)

Wymore, Adam S.; Potter, Jody; Rodríguez-Cardona, Bianca; McDowell, William H.

2018-04-01

The advent of high-frequency in situ optical sensors provides new opportunities to study the biogeochemistry of dissolved organic matter (DOM) in aquatic ecosystems. We used fDOM (fluorescent dissolved organic matter) to examine the spatial and temporal variability in dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) across a heterogeneous stream network that varies in NO3- concentration. Across the ten study streams fDOM explained twice the variability in the concentration of DOC (r2 = 0.82) compared to DON (r2 = 0.39), which suggests that the N-rich fraction of DOM is either more variable in its sources or more bioreactive than the more stable C-rich fraction. Among sites, DON molar fluorescence was approximately 3x more variable than DOC molar fluorescence and was correlated with changes in inorganic N, indicating that DON is both more variable in composition as well as highly responsive to changes in inorganic N. Laboratory results also indicate that the fDOM sensors we used perform as well as the excitation-emission wavelength pair generally referred to as the "tryptophan-like" peak when measured under laboratory conditions. However, since neither the field sensor not the laboratory measurements explained a large percentage of variation in DON concentrations, challenges still remain for monitoring the ambient pool of dissolved organic nitrogen. Sensor networks provide new insights into the potential reactivity of DOM and the variability in DOC and DON biogeochemistry across sites. These insights are needed to build spatially explicit models describing organic matter dynamics and water quality.

Interannual and seasonal variability of winter-spring cohort of neon flying squid abundance in the Northwest Pacific Ocean during 1995-2011

NASA Astrophysics Data System (ADS)

Yu, Wei; Chen, Xinjun; Yi, Qian

2016-06-01

The neon flying squid, Ommastrephes bartramii, is a species of economically important cephalopod in the Northwest Pacific Ocean. Its short lifespan increases the susceptibility of the distribution and abundance to the direct impact of the environmental conditions. Based on the generalized linear model (GLM) and generalized additive model (GAM), the commercial fishery data from the Chinese squid-jigging fleets during 1995 to 2011 were used to examine the interannual and seasonal variability in the abundance of O. bartramii, and to evaluate the influences of variables on the abundance (catch per unit effort, CPUE). The results from GLM suggested that year, month, latitude, sea surface temperature (SST), mixed layer depth (MLD), and the interaction term ( SST×MLD) were significant factors. The optimal model based on GAM included all the six significant variables and could explain 42.43% of the variance in nominal CPUE. The importance of the six variables was ranked by decreasing magnitude: year, month, latitude, SST, MLD and SST×MLD. The squid was mainly distributed in the waters between 40°N and 44°N in the Northwest Pacific Ocean. The optimal ranges of SST and MLD were from 14 to 20°C and from 10 to 30 m, respectively. The squid abundance greatly fluctuated from 1995 to 2011. The CPUE was low during 1995-2002 and high during 2003-2008. Furthermore, the squid abundance was typically high in August. The interannual and seasonal variabilities in the squid abundance were associated with the variations of marine environmental conditions and the life history characteristics of squid.

Puffed-up but shaky selves: State self-esteem level and variability in narcissists.

PubMed

Geukes, Katharina; Nestler, Steffen; Hutteman, Roos; Dufner, Michael; Küfner, Albrecht C P; Egloff, Boris; Denissen, Jaap J A; Back, Mitja D

2017-05-01

Different theoretical conceptualizations characterize grandiose narcissists by high, yet fragile self-esteem. Empirical evidence, however, has been inconsistent, particularly regarding the relationship between narcissism and self-esteem fragility (i.e., self-esteem variability). Here, we aim at unraveling this inconsistency by disentangling the effects of two theoretically distinct facets of narcissism (i.e., admiration and rivalry) on the two aspects of state self-esteem (i.e., level and variability). We report on data from a laboratory-based and two field-based studies (total N = 596) in realistic social contexts, capturing momentary, daily, and weekly fluctuations of state self-esteem. To estimate unbiased effects of narcissism on the level and variability of self-esteem within one model, we applied mixed-effects location scale models. Results of the three studies and their meta-analytical integration indicated that narcissism is positively linked to self-esteem level and variability. When distinguishing between admiration and rivalry, however, an important dissociation was identified: Admiration was related to high (and rather stable) levels of state self-esteem, whereas rivalry was related to (rather low and) fragile self-esteem. Analyses on underlying processes suggest that effects of rivalry on self-esteem variability are based on stronger decreases in self-esteem from one assessment to the next, particularly after a perceived lack of social inclusion. The revealed differentiated effects of admiration and rivalry explain why the analysis of narcissism as a unitary concept has led to the inconsistent past findings and provide deeper insights into the intrapersonal dynamics of grandiose narcissism governing state self-esteem. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Predictors of student success in entry-level science courses

NASA Astrophysics Data System (ADS)

Singh, Mamta K.

Although the educational evaluation process is useful and valuable and is supported by the Higher Education Act, a strong research base for program evaluation of college entry-level science courses is still lacking. Studies in science disciplines such as, biology, chemistry, and physics have addressed various affective and demographic factors and their relationships to student achievement. However, the literature contains little information that specifically addresses student biology content knowledge skills (basics and higher order thinking skills) and identifies factors that affect students' success in entry-level college science courses. These gate-keeping courses require detailed evaluation if the goal of an institution is to increase students' performance and success in these courses. These factors are, in fact, a stepping stone for increasing the number of graduates in Science, Technology, Engineering, and Mathematics (STEM) majors. The present study measured students' biology content knowledge and investigated students' performance and success in college biology, chemistry, and physics entry-level courses. Seven variables---gender, ethnicity, high school Grade Point Average (GPA), high school science, college major, school financial aid support, and work hours were used as independent variables and course final performance as a dichotomous dependent variable. The sample comprised voluntary student participants in entry-level science courses. The study attempted to explore eight research questions. Content knowledge assessments, demographic information analysis, multiple regression analysis, and binary logistic regression analysis were used to address research questions. The results suggested that high school GPA was a consistently good predictor of students' performance and success in entry-level science courses. Additionally, high school chemistry was a significant predictor variable for student success in entry-level biology and chemistry courses. Similarly, students' performance and success in entry-level physics courses were influenced by high school physics. Finally, the study developed student success equation with high school GAP and high school chemistry as good predictors of students' success in entry-level science courses.

The effect of modeled absolute timing variability and relative timing variability on observational learning.

PubMed

Grierson, Lawrence E M; Roberts, James W; Welsher, Arthur M

2017-05-01

There is much evidence to suggest that skill learning is enhanced by skill observation. Recent research on this phenomenon indicates a benefit of observing variable/erred demonstrations. In this study, we explore whether it is variability within the relative organization or absolute parameterization of a movement that facilitates skill learning through observation. To do so, participants were randomly allocated into groups that observed a model with no variability, absolute timing variability, relative timing variability, or variability in both absolute and relative timing. All participants performed a four-segment movement pattern with specific absolute and relative timing goals prior to and following the observational intervention, as well as in a 24h retention test and transfers tests that featured new relative and absolute timing goals. Absolute timing error indicated that all groups initially acquired the absolute timing, maintained their performance at 24h retention, and exhibited performance deterioration in both transfer tests. Relative timing error revealed that the observation of no variability and relative timing variability produced greater performance at the post-test, 24h retention and relative timing transfer tests, but for the no variability group, deteriorated at absolute timing transfer test. The results suggest that the learning of absolute timing following observation unfolds irrespective of model variability. However, the learning of relative timing benefits from holding the absolute features constant, while the observation of no variability partially fails in transfer. We suggest learning by observing no variability and variable/erred models unfolds via similar neural mechanisms, although the latter benefits from the additional coding of information pertaining to movements that require a correction. Copyright © 2017 Elsevier B.V. All rights reserved.

High-resolution TNG spectra of T Tauri stars. Near-IR GIANO observations of the young variables XZ Tauri and DR Tauri

NASA Astrophysics Data System (ADS)

Antoniucci, S.; Nisini, B.; Biazzo, K.; Giannini, T.; Lorenzetti, D.; Sanna, N.; Harutyunyan, A.; Origlia, L.; Oliva, E.

2017-10-01

Aims: We aim to characterise the star-disk interaction region in T Tauri stars that show photometric and spectroscopic variability. Methods: We used the GIANO instrument at the Telescopio Nazionale Galileo to obtain near-infrared high-resolution spectra (R 50 000) of XZ Tau and DR Tau, which are two actively accreting T Tauri stars classified as EXors. Equivalent widths and profiles of the observed features are used to derive information on the properties of the inner disk, the accretion columns, and the winds. Results: Both sources display composite H I line profiles, where contributions from both accreting gas and high-velocity winds can be recognised. These lines are progressively more symmetric and narrower with increasing upper energy which may be interpreted in terms of two components with different decrements or imputed to self-absorption effects. XZ Tau is observed in a relatively high state of activity with respect to literature observations. The variation of the He I 1.08 μm line blue-shifted absorption, in particular, suggests that the inner wind has undergone a dramatic change in its velocity structure, connected with a recent accretion event. DR Tau has a more stable wind as its He I 1.08 μm absorption does not show variations with time in spite of strong variability of the emission component. The IR veiling in the two sources can be interpreted as due to blackbody emission at temperatures of 1600 K and 2300 K for XZ Tau and DR Tau, respectively, with emitting areas 30 times larger than the central star. While for XZ Tau these conditions are consistent with emission from the inner rim of the dusty disk, the fairly high temperature inferred for DR Tau might suggest that its veiling originates from a thick gaseous disk located within the dust sublimation radius. Strong and broad metallic lines, mainly from C I and Fe I, are detected in XZ Tau, similar to those observed in other EXor sources during burst phases. At variance, DR Tau shows weaker and narrower metallic lines, despite its larger accretion luminosity. This suggests that accretion is not the only driver of metallic line excitation. Conclusions: The presented observations demonstrate the potential of wide-band, high-resolution near-IR spectroscopy to simultaneously probe the different phenomena that occur in the interaction region between the stellar magnetosphere and the accretion disk, thus providing hints on how these two structures are linked to each other.

Synchronous fire activity in the tropical high Andes: an indication of regional climate forcing.

PubMed

Román-Cuesta, R M; Carmona-Moreno, C; Lizcano, G; New, M; Silman, M; Knoke, T; Malhi, Y; Oliveras, I; Asbjornsen, H; Vuille, M

2014-06-01

Global climate models suggest enhanced warming of the tropical mid and upper troposphere, with larger temperature rise rates at higher elevations. Changes in fire activity are amongst the most significant ecological consequences of rising temperatures and changing hydrological properties in mountainous ecosystems, and there is a global evidence of increased fire activity with elevation. Whilst fire research has become popular in the tropical lowlands, much less is known of the tropical high Andean region (>2000 masl, from Colombia to Bolivia). This study examines fire trends in the high Andes for three ecosystems, the Puna, the Paramo and the Yungas, for the period 1982-2006. We pose three questions: (i) is there an increased fire response with elevation? (ii) does the El Niño- Southern Oscillation control fire activity in this region? (iii) are the observed fire trends human driven (e.g., human practices and their effects on fuel build-up) or climate driven? We did not find evidence of increased fire activity with elevation but, instead, a quasicyclic and synchronous fire response in Ecuador, Peru and Bolivia, suggesting the influence of high-frequency climate forcing on fire responses on a subcontinental scale, in the high Andes. ENSO variability did not show a significant relation to fire activity for these three countries, partly because ENSO variability did not significantly relate to precipitation extremes, although it strongly did to temperature extremes. Whilst ENSO did not individually lead the observed regional fire trends, our results suggest a climate influence on fire activity, mainly through a sawtooth pattern of precipitation (increased rainfall before fire-peak seasons (t-1) followed by drought spells and unusual low temperatures (t0), which is particularly common where fire is carried by low fuel loads (e.g., grasslands and fine fuel). This climatic sawtooth appeared as the main driver of fire trends, above local human influences and fuel build-up cyclicity. © 2014 John Wiley & Sons Ltd.

Voluntary running of defined distances reduces body adiposity and its associated inflammation in C57BL/6 mice fed a high-fat diet.

PubMed

Yan, Lin; Sundaram, Sneha; Nielsen, Forrest H

2017-11-01

This study investigated the effect of voluntary running of defined distances on body adiposity in male C57BL/6 mice fed a high-fat diet. Mice were assigned to 6 groups and fed a standard AIN93G diet (sedentary) or a modified high-fat AIN93G diet (sedentary; unrestricted running; or 75%, 50%, or 25% of unrestricted running) for 12 weeks. The average running distance was 8.3, 6.3, 4.2, and 2.1 km/day for the unrestricted, 75%, 50%, and 25% of unrestricted runners, respectively. Body adiposity was 46% higher in sedentary mice when fed the high-fat diet instead of the standard diet. Running decreased adiposity in mice fed the high-fat diet in a dose-dependent manner but with no significant difference between sedentary mice and those running 2.1 km/day. In sedentary mice, the high-fat instead of the standard diet increased insulin resistance, hepatic triacylglycerides, and adipose and plasma concentrations of leptin and monocyte chemotactic protein-1 (MCP-1). Running reduced these variables in a dose-dependent manner. Adipose adiponectin was lowest in sedentary mice fed the high-fat diet; running raised adiponectin in both adipose tissue and plasma. Running 8.3 and 6.3 km/day had the greatest, but similar, effects on the aforementioned variables. Running 2.1 km/day did not affect these variables except, when compared with sedentariness, it significantly decreased MCP-1. The findings showed that running 6.3 kg/day was optimal for reducing adiposity and associated inflammation that was increased in mice by feeding a high-fat diet. The findings suggest that voluntary running of defined distances may counteract the obesogenic effects of a high-fat diet.

Moving forward socio-economically focused models of deforestation.

PubMed

Dezécache, Camille; Salles, Jean-Michel; Vieilledent, Ghislain; Hérault, Bruno

2017-09-01

Whilst high-resolution spatial variables contribute to a good fit of spatially explicit deforestation models, socio-economic processes are often beyond the scope of these models. Such a low level of interest in the socio-economic dimension of deforestation limits the relevancy of these models for decision-making and may be the cause of their failure to accurately predict observed deforestation trends in the medium term. This study aims to propose a flexible methodology for taking into account multiple drivers of deforestation in tropical forested areas, where the intensity of deforestation is explicitly predicted based on socio-economic variables. By coupling a model of deforestation location based on spatial environmental variables with several sub-models of deforestation intensity based on socio-economic variables, we were able to create a map of predicted deforestation over the period 2001-2014 in French Guiana. This map was compared to a reference map for accuracy assessment, not only at the pixel scale but also over cells ranging from 1 to approximately 600 sq. km. Highly significant relationships were explicitly established between deforestation intensity and several socio-economic variables: population growth, the amount of agricultural subsidies, gold and wood production. Such a precise characterization of socio-economic processes allows to avoid overestimation biases in high deforestation areas, suggesting a better integration of socio-economic processes in the models. Whilst considering deforestation as a purely geographical process contributes to the creation of conservative models unable to effectively assess changes in the socio-economic and political contexts influencing deforestation trends, this explicit characterization of the socio-economic dimension of deforestation is critical for the creation of deforestation scenarios in REDD+ projects. © 2017 John Wiley & Sons Ltd.

Communication of mechanically ventilated patients in intensive care units

PubMed Central

Martinho, Carina Isabel Ferreira; Rodrigues, Inês Tello Rato Milheiras

2016-01-01

Objective The aim of this study was to translate and culturally and linguistically adapt the Ease of Communication Scale and to assess the level of communication difficulties for patients undergoing mechanical ventilation with orotracheal intubation, relating these difficulties to clinical and sociodemographic variables. Methods This study had three stages: (1) cultural and linguistic adaptation of the Ease of Communication Scale; (2) preliminary assessment of its psychometric properties; and (3) observational, descriptive-correlational and cross-sectional study, conducted from March to August 2015, based on the Ease of Communication Scale - after extubation answers and clinical and sociodemographic variables of 31 adult patients who were extubated, clinically stable and admitted to five Portuguese intensive care units. Results Expert analysis showed high agreement on content (100%) and relevance (75%). The pretest scores showed a high acceptability regarding the completion of the instrument and its usefulness. The Ease of Communication Scale showed excellent internal consistency (0.951 Cronbach's alpha). The factor analysis explained approximately 81% of the total variance with two scale components. On average, the patients considered the communication experiences during intubation to be "quite hard" (2.99). No significant correlation was observed between the communication difficulties reported and the studied sociodemographic and clinical variables, except for the clinical variable "number of hours after extubation" (p < 0.05). Conclusion This study translated and adapted the first assessment instrument of communication difficulties for mechanically ventilated patients in intensive care units into European Portuguese. The preliminary scale validation suggested high reliability. Patients undergoing mechanical ventilation reported that communication during intubation was "quite hard", and these communication difficulties apparently existed regardless of the presence of other clinical and/or sociodemographic variables. PMID:27410408

Alleviating tropical Atlantic sector biases in the Kiel climate model by enhancing horizontal and vertical atmosphere model resolution: climatology and interannual variability

NASA Astrophysics Data System (ADS)

Harlaß, Jan; Latif, Mojib; Park, Wonsun

2018-04-01

We investigate the quality of simulating tropical Atlantic (TA) sector climatology and interannual variability in integrations of the Kiel climate model (KCM) with varying atmosphere model resolution. The ocean model resolution is kept fixed. A reasonable simulation of TA sector annual-mean climate, seasonal cycle and interannual variability can only be achieved at sufficiently high horizontal and vertical atmospheric resolution. Two major reasons for the improvements are identified. First, the western equatorial Atlantic westerly surface wind bias in spring can be largely eliminated, which is explained by a better representation of meridional and especially vertical zonal momentum transport. The enhanced atmospheric circulation along the equator in turn greatly improves the thermal structure of the upper equatorial Atlantic with much reduced warm sea surface temperature (SST) biases. Second, the coastline in the southeastern TA and steep orography are better resolved at high resolution, which improves wind structure and in turn reduces warm SST biases in the Benguela upwelling region. The strongly diminished wind and SST biases at high atmosphere model resolution allow for a more realistic latitudinal position of the intertropical convergence zone. Resulting stronger cross-equatorial winds, in conjunction with a shallower thermocline, enable a rapid cold tongue development in the eastern TA in boreal spring. This enables simulation of realistic interannual SST variability and its seasonal phase locking in the KCM, which primarily is the result of a stronger thermocline feedback. Our findings suggest that enhanced atmospheric resolution, both vertical and horizontal, could be a key to achieving more realistic simulation of TA climatology and interannual variability in climate models.

A Search for Pulsation in Young Brown Dwarfs and Very Low Mass Stars

NASA Astrophysics Data System (ADS)

Cody, Ann Marie

2012-05-01

In 2005, Palla and Baraffe proposed that brown dwarfs and very low mass stars (<0.1 solar masses) may be unstable to radial oscillations during the pre-main-sequence deuterium burning phase. With associated oscillation periods of 1--4 hours, this potentially new class of pulsation offers unprecedented opportunities to probe the interiors and evolution of low-mass objects in the 1--15 million year age range. Furthermore, several previous reports of short-period variability have suggested that deuterium-burning pulsation is in fact at work in young clusters. For my dissertation, I developed a photometric monitoring campaign to search for low-amplitude periodic variability in young brown dwarfs and very low mass stars using meter-class telescopes from both the ground and space. The resulting high-precision, high-cadence time-series photometry targeted four young clusters and achieved sensitivity to periodic oscillations with photometric amplitudes down to several millimagnitudes. This unprecedented variability census probed timescales ranging from minutes to weeks in a sample of 200 young, low-mass cluster members of IC 348, Sigma Orionis, Chamaeleon I, and Upper Scorpius. While I find a dearth of photometric periods under 10 hours, the campaign's high time resolution and precision have enabled detailed study of diverse light curve behavior in the clusters: rotational spot modulation, accretion signatures, and occultations by surrounding disk material. Analysis of the data has led to the establishment of a lower limit for the timescale of periodic photometric variability in young low-mass and substellar objects, an extension of the rotation period distribution to the brown dwarf regime, as well as insights into the connection between variability and circumstellar disks in the Sigma Orionis and Chamaeleon I clusters.

Predicting academic performance of medical students: the first three years.

PubMed

Höschl, C; Kozený, J

1997-06-01

The purpose of this exploratory study was to identify a cluster of variables that would most economically explain variations in the grade point averages of medical students during the first 3 years of study. Data were derived from a study of 92 students admitted to the 3rd Faculty of Medicine in 1992-1993 academic year and who were still in the medical school at the end of the sixth semester (third year). Stepwise regression analysis was used to build models for predicting log-transformed changes in grade point average after six semesters of study-at the end of the first, second, and third years. Predictor variables were chosen from four domains: 1) high school grade point averages in physics, mathematics, and the Czech language over 4 years of study, 2) results of admission tests in biology, chemistry, and physics, 3) admission committee's assessment of the applicant's ability to reproduce a text, motivation to study medicine, and social maturity, and 4) scores on the sentimentality and attachment scales of the Tridimensional Personality Questionnaire. The regression model, which included performance in high school physics, results of the admission test in physics, assessment of the applicant's motivation to study medicine, and attachment scale score, accounted for 32% of the change in grade point average over six semesters of study. The regression models using the first-, second-, and third-year grade point averages as the dependent variables showed slightly decreasing amounts of explained variance toward the end of the third year of study and within domains, changing the structure of predictor variables. The results suggest that variables chosen from the assessment domains of high school performance, written entrance examination, admission interview, and personality traits may be significant predictors of academic success during the first 3 years of medical study.

Inferior outcomes for black children with high risk acute lymphoblastic leukemia and the impact of socioeconomic variables.

PubMed

Walsh, Alexandra; Chewning, Joseph; Li, Xuelin; Dai, Chen; Whelan, Kimberly; Madan-Swain, Avi; Waterbor, John; Baskin, Monica L; Goldman, Frederick D

2017-02-01

While significant improvements have been made for children with acute lymphoblastic leukemia (ALL) in the United States over the past 20 years, black patients continue to have inferior outcomes. The full impact of socioeconomic variables on outcomes in this minority population is not entirely understood. Disease characteristics, demographic, and socioeconomic status (SES) variables were collected on black (n = 44) and white (n = 178) patients diagnosed at the University of Alabama at Birmingham. Cox proportional hazard regression was used to evaluate the influence of SES and insurance status on survival. As a cohort, 5-year overall survival (OS) was 87% (82-91%), with a median follow-up of 99 months. In univariable analysis, black race was not significantly associated with a higher risk of death or relapse and death. White and black patients with standard-risk leukemia had excellent outcomes, with 97% (91-99%) and 96% (75-99%) 5-year OS, respectively. In contrast, for high-risk disease, white patients had a statistically significant improved 5-year OS rates compared with black patients (79% [68-87%] vs. 52% [28-72%]). Black children were more likely to have public insurance, and, in multivariable analysis, this was associated with a trend toward an improved outcome. Black patients also had poorer census tract-level SES parameters, but these variables were not associated with survival. Our study demonstrates significantly inferior outcomes for black children with high-risk leukemia. These outcome disparities were not related to SES variables, including poverty or private insurance coverage, suggesting the involvement of other factors and highlighting the need for a prospective investigative analysis. © 2016 Wiley Periodicals, Inc.

Influence of the Bermuda High on interannual variability of summertime ozone in the Houston-Galveston-Brazoria region

NASA Astrophysics Data System (ADS)

Wang, Yuxuan; Jia, Beixi; Wang, Sing-Chun; Estes, Mark; Shen, Lu; Xie, Yuanyu

2016-12-01

The Bermuda High (BH) quasi-permanent pressure system is the key large-scale circulation pattern influencing summertime weather over the eastern and southern US. Here we developed a multiple linear regression (MLR) model to characterize the effect of the BH on year-to-year changes in monthly-mean maximum daily 8 h average (MDA8) ozone in the Houston-Galveston-Brazoria (HGB) metropolitan region during June, July, and August (JJA). The BH indicators include the longitude of the BH western edge (BH-Lon) and the BH intensity index (BHI) defined as the pressure gradient along its western edge. Both BH-Lon and BHI are selected by MLR as significant predictors (p < 0.05) of the interannual (1990-2015) variability of the HGB-mean ozone throughout JJA, while local-scale meridional wind speed is selected as an additional predictor for August only. Local-scale temperature and zonal wind speed are not identified as important factors for any summer month. The best-fit MLR model can explain 61-72 % of the interannual variability of the HGB-mean summertime ozone over 1990-2015 and shows good performance in cross-validation (R2 higher than 0.48). The BH-Lon is the most important factor, which alone explains 38-48 % of such variability. The location and strength of the Bermuda High appears to control whether or not low-ozone maritime air from the Gulf of Mexico can enter southeastern Texas and affect air quality. This mechanism also applies to other coastal urban regions along the Gulf Coast (e.g., New Orleans, LA, Mobile, AL, and Pensacola, FL), suggesting that the BH circulation pattern can affect surface ozone variability through a large portion of the Gulf Coast.

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.

A map of human microRNA variation uncovers unexpectedly high levels of variability

PubMed Central

2012-01-01

Background MicroRNAs (miRNAs) are key components of the gene regulatory network in many species. During the past few years, these regulatory elements have been shown to be involved in an increasing number and range of diseases. Consequently, the compilation of a comprehensive map of natural variability in a healthy population seems an obvious requirement for future research on miRNA-related pathologies. Methods Data on 14 populations from the 1000 Genomes Project were analyzed, along with new data extracted from 60 exomes of healthy individuals from a population from southern Spain, sequenced in the context of the Medical Genome Project, to derive an accurate map of miRNA variability. Results Despite the common belief that miRNAs are highly conserved elements, analysis of the sequences of the 1,152 individuals indicated that the observed level of variability is double what was expected. A total of 527 variants were found. Among these, 45 variants affected the recognition region of the corresponding miRNA and were found in 43 different miRNAs, 26 of which are known to be involved in 57 diseases. Different parts of the mature structure of the miRNA were affected to different degrees by variants, which suggests the existence of a selective pressure related to the relative functional impact of the change. Moreover, 41 variants showed a significant deviation from the Hardy-Weinberg equilibrium, which supports the existence of a selective process against some alleles. The average number of variants per individual in miRNAs was 28. Conclusions Despite an expectation that miRNAs would be highly conserved genomic elements, our study reports a level of variability comparable to that observed for coding genes. PMID:22906193

How Changes in Psychosocial Job Characteristics Impact Burnout in Nurses: A Longitudinal Analysis.

PubMed

Pisanti, Renato; van der Doef, Margot; Maes, Stan; Meier, Laurenz Linus; Lazzari, David; Violani, Cristiano

2016-01-01

The main aim of this longitudinal study was to test the Job Demand-Control-Support (JDCS) model and to analyze whether changes in psychosocial job characteristics are related to (changes in) burnout. Previous studies on the effects of JDCS variables on burnout dimensions have indicated that the iso-strain hypothesis (i.e., high job demands, low control, and low support additively predict high stress reactions) and the buffer hypotheses (i.e., high job control and/or social support is expected to moderate the negative impact of high demands on stress reactions) have hardly been examined concurrently in a longitudinal design; and that the effects of changes of psychosocial job variables on burnout dimensions have hardly been analyzed. This two wave study was carried out over a period of 14 months in a sample of 217 Italian nurses. Hierarchical regression analyses were used to test the cross lagged main and interactive effects of JDCS variables, and to analyse the across-time effects of changes in JDCS dimensions on burnout variables. The Time 1 job characteristics explained 2-8% of the variance in the Time 2 burnout dimensions, but no support for the additive, or the buffer hypothesis of the JDCS model was found. Changes in job characteristics explained an additional 3-20% of variance in the Time 2 burnout dimensions. Specifically, high levels of emotional exhaustion at Time 2 were explained by high levels of social support at Time 1, and unfavorable changes in demands, control, and support over time; high depersonalization at Time 2 was explained by high social support at time 1 and by an increase in demands over time; and high personal accomplishment at Time 2 was predicted by high demands, high control, interactive effect demands × control × social support, at Time 1, and by a decrease in demands over time. No reversed effects of burnout on work characteristics have been found. Our findings suggest that the work environment is subject to changes: the majority of employees experienced considerable changes in all job conditions over time. These changes impacted employee burnout. Limitations and implications of the study are discussed.

How Changes in Psychosocial Job Characteristics Impact Burnout in Nurses: A Longitudinal Analysis

PubMed Central

Pisanti, Renato; van der Doef, Margot; Maes, Stan; Meier, Laurenz Linus; Lazzari, David; Violani, Cristiano

2016-01-01

Aims: The main aim of this longitudinal study was to test the Job Demand-Control-Support (JDCS) model and to analyze whether changes in psychosocial job characteristics are related to (changes in) burnout. Background: Previous studies on the effects of JDCS variables on burnout dimensions have indicated that the iso-strain hypothesis (i.e., high job demands, low control, and low support additively predict high stress reactions) and the buffer hypotheses (i.e., high job control and/or social support is expected to moderate the negative impact of high demands on stress reactions) have hardly been examined concurrently in a longitudinal design; and that the effects of changes of psychosocial job variables on burnout dimensions have hardly been analyzed. Design: This two wave study was carried out over a period of 14 months in a sample of 217 Italian nurses. Method: Hierarchical regression analyses were used to test the cross lagged main and interactive effects of JDCS variables, and to analyse the across-time effects of changes in JDCS dimensions on burnout variables. Results: The Time 1 job characteristics explained 2–8% of the variance in the Time 2 burnout dimensions, but no support for the additive, or the buffer hypothesis of the JDCS model was found. Changes in job characteristics explained an additional 3–20% of variance in the Time 2 burnout dimensions. Specifically, high levels of emotional exhaustion at Time 2 were explained by high levels of social support at Time 1, and unfavorable changes in demands, control, and support over time; high depersonalization at Time 2 was explained by high social support at time 1 and by an increase in demands over time; and high personal accomplishment at Time 2 was predicted by high demands, high control, interactive effect demands × control × social support, at Time 1, and by a decrease in demands over time. No reversed effects of burnout on work characteristics have been found. Conclusion: Our findings suggest that the work environment is subject to changes: the majority of employees experienced considerable changes in all job conditions over time. These changes impacted employee burnout. Limitations and implications of the study are discussed. PMID:27507952

Molluscan sclerochronology on the Faroese Shelf and its potential to obtain closer insights into the climate variability of North Atlantic water masses

NASA Astrophysics Data System (ADS)

Bonitz, F. G. W.; Andersson Dahl, C.; Trofimova, T.

2016-12-01

In this study, we investigate the climate variability in the North Atlantic during the last 350 years by applying sclerochronological methods. The inflow of North Atlantic water masses into the Arctic and the Norwegian Sea is important for the climate in these regions. A better understanding of the climate variability on highly resolved time scales is needed to obtain a better fundament for climate predictions for these areas. However, highly resolved paleoclimate records are sparse in the North Atlantic and instrumental data cover only the last 50 - 150 years. Bivalve shells provide highly resolved climate archives, especially the shells of the long-lived bivalve species Arctica islandica. This widely occurring species forms annual growth increments, which can be analyzed similarly to tree rings. Climatic and oceanographic changes are recorded population-wide in the shell`s growth rate and in the isotopic composition of the shell. Hence, multi-centennial absolutely dated chronologies can be built by cross-matching live-collected and sub-fossil specimens. Our chronology building effort has led to the first multi-centennial absolutely dated chronology from the Faroese Shelf covering the time period from AD 1642 - 2013. The growth indices of the chronology anti-correlate with April - September sea surface temperatures (SST) for the last 100 years indicating favorable conditions for growth when temperatures are lower. This also suggests that the main growing season of A. islandica around the Faroe Islands occurs in this time period; a hypothesis supported by δ18O-based temperature reconstructions from growth increments representing the years 2001 - 2013. The RBAR, which is an indicator for the signal strength throughout the chronology shows an inverse relationship with Atlantic Multi-decadal Oscillation (AMO) data indicating that periods of higher AMO indexes result in a weakened signal strength in the chronology for the same time period. In conclusion, our results suggest that a combination of the growth increment variability and δ18O measurements of the growth increments can provide a tool to obtain information about the year-to-year SST variability beyond instrumental observations and the signal strength throughout the chronology may provide information about the timing of major AMO shifts.

Temperature-Robust Neural Function from Activity-Dependent Ion Channel Regulation.

PubMed

O'Leary, Timothy; Marder, Eve

2016-11-07

Many species of cold-blooded animals experience substantial and rapid fluctuations in body temperature. Because biological processes are differentially temperature dependent, it is difficult to understand how physiological processes in such animals can be temperature robust [1-8]. Experiments have shown that core neural circuits, such as the pyloric circuit of the crab stomatogastric ganglion (STG), exhibit robust neural activity in spite of large (20°C) temperature fluctuations [3, 5, 7, 8]. This robustness is surprising because (1) each neuron has many different kinds of ion channels with different temperature dependencies (Q 10 s) that interact in a highly nonlinear way to produce firing patterns and (2) across animals there is substantial variability in conductance densities that nonetheless produce almost identical firing properties. The high variability in conductance densities in these neurons [9, 10] appears to contradict the possibility that robustness is achieved through precise tuning of key temperature-dependent processes. In this paper, we develop a theoretical explanation for how temperature robustness can emerge from a simple regulatory control mechanism that is compatible with highly variable conductance densities [11-13]. The resulting model suggests a general mechanism for how nervous systems and excitable tissues can exploit degenerate relationships among temperature-sensitive processes to achieve robust function. Copyright © 2016 Elsevier Ltd. All rights reserved.

Re-examining the effects of verbal instructional type on early stage motor learning.

PubMed

Bobrownicki, Ray; MacPherson, Alan C; Coleman, Simon G S; Collins, Dave; Sproule, John

2015-12-01

The present study investigated the differential effects of analogy and explicit instructions on early stage motor learning and movement in a modified high jump task. Participants were randomly assigned to one of three experimental conditions: analogy, explicit light (reduced informational load), or traditional explicit (large informational load). During the two-day learning phase, participants learned a novel high jump technique based on the 'scissors' style using the instructions for their respective conditions. For the single-day testing phase, participants completed both a retention test and task-relevant pressure test, the latter of which featured a rising high-jump-bar pressure manipulation. Although analogy learners demonstrated slightly more efficient technique and reported fewer technical rules on average, the differences between the conditions were not statistically significant. There were, however, significant differences in joint variability with respect to instructional type, as variability was lowest for the analogy condition during both the learning and testing phases, and as a function of block, as joint variability decreased for all conditions during the learning phase. Findings suggest that reducing the informational volume of explicit instructions may mitigate the deleterious effects on performance previously associated with explicit learning in the literature. Copyright © 2015 Elsevier B.V. All rights reserved.

An analysis of controls on fire activity in boreal Canada: comparing models built with different temporal resolutions

Treesearch

Marc-Andre Parisien; Sean A. Parks; Meg A. Krawchuk; John M. Little; Mike D. Flannigan; Lynn M. Gowman; Max A. Moritz

2014-01-01

Fire regimes of the Canadian boreal forest are driven by certain environmental factors that are highly variable from year to year (e.g., temperature, precipitation) and others that are relatively stable (e.g., land cover, topography). Studies examining the relative influence of these environmental drivers on fire activity suggest that models making explicit use of...

Test Candidates' Attitudes and Their Relationship to Demographic and Experiential Variables: The Case of Overseas Trained Teachers in NSW, Australia

ERIC Educational Resources Information Center

Murray, Jill C.; Riazi, A. Mehdi; Cross, Judith L.

2012-01-01

One measure of the impact of a high-stakes test is the attitudes that test takers hold towards it. It has been suggested that positive attitudes produce beneficial effects while real or anticipated negative experiences can result in the development of attitudes that erode confidence and potentially impact negatively on performance. This study…

Fear of Success, Sex-Role Orientation of the Task, and Competitive Condition as Variables Affecting Women's Performance in Achievement-Oriented Situations.

ERIC Educational Resources Information Center

Makosky, Vivian P.

It has been suggested that for women, success in competitive achievement situations may produce negative social sanctions, resulting in a motive to avoid success, which inhibits high performance in these situations. 120 college women, 60 exhibiting fear of success and 60 exhibiting no fear of success, based upon results of a projective measure,…

Complex Morphological Variability in Complex Evaporitic Systems: Thermal Spring Snails from the Chihuahuan Desert, Mexico

NASA Astrophysics Data System (ADS)

Tang, Carol M.; Roopnarine, Peter D.

2003-11-01

Thermal springs in evaporitic environments provide a unique biological laboratory in which to study natural selection and evolutionary diversification. These isolated systems may be an analogue for conditions in early Earth or Mars history. One modern example of such a system can be found in the Chihuahuan Desert of north-central Mexico. The Cuatro Cienegas basin hosts a series of thermal springs that form a complex of aquatic ecosystems under a range of environmental conditions. Using landmark-based morphometric techniques, we have quantified an unusually high level of morphological variability in the endemic gastropod Mexipyrgus from Cuatro Cienegas. The differentiation is seen both within and between hydrological systems. Our results suggest that this type of environmental system is capable of producing and maintaining a high level of morphological diversity on small spatial scales, and thus should be a target for future astrobiological research.

Fifty Years of Research in ARDS. Respiratory Mechanics in Acute Respiratory Distress Syndrome.

PubMed

Henderson, William R; Chen, Lu; Amato, Marcelo B P; Brochard, Laurent J

2017-10-01

Acute respiratory distress syndrome is a multifactorial lung injury that continues to be associated with high levels of morbidity and mortality. Mechanical ventilation, although lifesaving, is associated with new iatrogenic injury. Current best practice involves the use of small Vt, low plateau and driving pressures, and high levels of positive end-expiratory pressure. Collectively, these interventions are termed "lung-protective ventilation." Recent investigations suggest that individualized measurements of pulmonary mechanical variables rather than population-based ventilation prescriptions may be used to set the ventilator with the potential to improve outcomes beyond those achieved with standard lung protective ventilation. This review outlines the measurement and application of clinically applicable pulmonary mechanical concepts, such as plateau pressures, driving pressure, transpulmonary pressures, stress index, and measurement of strain. In addition, the concept of the "baby lung" and the utility of dynamic in addition to static measures of pulmonary mechanical variables are discussed.

Self-Esteem, Locus of Control, and First-Time NCLEX-RN Passage of BSN Students at Historically Black Colleges and Universities.

PubMed

Chavis, Pamella Ivey

Relationships between self-esteem, locus of control (LOC), and first-time passage of National Council Licensure Examination for Registered Nurses (NCLEX-RN®) were examined at baccalaureate nursing programs at two historically black colleges and universities. Shortages continue to exceed demands for RNs prepared at the baccalaureate level. Inconsistent pass rates on the NCLEX-RN for graduates of historically black colleges and universities impede the supply of RNs. Surveys and archival data were used to examine characteristics of the sample and explore relationships among variables. All participants (N = 90) reported high self-esteem and internal LOC. Models suggested that all those with high self-esteem and internal LOC would pass the NCLEX-RN; only 85 percent passed the first time. Statistical analysis revealed a lack of statistical significance between self-esteem, LOC, and first-time passage. Variables not included in the study may have affected first-time passage.

Soundscapes from a Tropical Eastern Pacific reef and a Caribbean Sea reef

NASA Astrophysics Data System (ADS)

Staaterman, E.; Rice, A. N.; Mann, D. A.; Paris, C. B.

2013-06-01

Underwater soundscapes vary due to the abiotic and biological components of the habitat. We quantitatively characterized the acoustic environments of two coral reef habitats, one in the Tropical Eastern Pacific (Panama) and one in the Caribbean (Florida Keys), over 2-day recording durations in July 2011. We examined the frequency distribution, temporal variability, and biological patterns of sound production and found clear differences. The Pacific reef exhibited clear biological patterns and high temporal variability, such as the onset of snapping shrimp noise at night, as well as a 400-Hz daytime band likely produced by damselfish. In contrast, the Caribbean reef had high sound levels in the lowest frequencies, but lacked clear temporal patterns. We suggest that acoustic measures are an important element to include in reef monitoring programs, as the acoustic environment plays an important role in the ecology of reef organisms at multiple life-history stages.

Constraints on the Genetic and Antigenic Variability of Measles Virus.

PubMed

Beaty, Shannon M; Lee, Benhur

2016-04-21

Antigenic drift and genetic variation are significantly constrained in measles virus (MeV). Genetic stability of MeV is exceptionally high, both in the lab and in the field, and few regions of the genome allow for rapid genetic change. The regions of the genome that are more tolerant of mutations (i.e., the untranslated regions and certain domains within the N, C, V, P, and M proteins) indicate genetic plasticity or structural flexibility in the encoded proteins. Our analysis reveals that strong constraints in the envelope proteins (F and H) allow for a single serotype despite known antigenic differences among its 24 genotypes. This review describes some of the many variables that limit the evolutionary rate of MeV. The high genomic stability of MeV appears to be a shared property of the Paramyxovirinae, suggesting a common mechanism that biologically restricts the rate of mutation.

Constraints on the Genetic and Antigenic Variability of Measles Virus

PubMed Central

Beaty, Shannon M.; Lee, Benhur

2016-01-01

Antigenic drift and genetic variation are significantly constrained in measles virus (MeV). Genetic stability of MeV is exceptionally high, both in the lab and in the field, and few regions of the genome allow for rapid genetic change. The regions of the genome that are more tolerant of mutations (i.e., the untranslated regions and certain domains within the N, C, V, P, and M proteins) indicate genetic plasticity or structural flexibility in the encoded proteins. Our analysis reveals that strong constraints in the envelope proteins (F and H) allow for a single serotype despite known antigenic differences among its 24 genotypes. This review describes some of the many variables that limit the evolutionary rate of MeV. The high genomic stability of MeV appears to be a shared property of the Paramyxovirinae, suggesting a common mechanism that biologically restricts the rate of mutation. PMID:27110809

Comparison of Procedures for Dual and Triple Closely Spaced Parallel Runways

NASA Technical Reports Server (NTRS)

Verma, Savita; Ballinger, Deborah; Subramanian Shobana; Kozon, Thomas

2012-01-01

A human-in-the-loop high fidelity flight simulation experiment was conducted, which investigated and compared breakout procedures for Very Closely Spaced Parallel Approaches (VCSPA) with two and three runways. To understand the feasibility, usability and human factors of two and three runway VCSPA, data were collected and analyzed on the dependent variables of breakout cross track error and pilot workload. Independent variables included number of runways, cause of breakout and location of breakout. Results indicated larger cross track error and higher workload using three runways as compared to 2-runway operations. Significant interaction effects involving breakout cause and breakout location were also observed. Across all conditions, cross track error values showed high levels of breakout trajectory accuracy and pilot workload remained manageable. Results suggest possible avenues of future adaptation for adopting these procedures (e.g., pilot training), while also showing potential promise of the concept.

Transcript expression and genetic variability analysis of caspases in breast carcinomas suggests CASP9 as the most interesting target.

PubMed

Brynychova, Veronika; Hlavac, Viktor; Ehrlichova, Marie; Vaclavikova, Radka; Nemcova-Furstova, Vlasta; Pecha, Vaclav; Trnkova, Marketa; Mrhalova, Marcela; Kodet, Roman; Vrana, David; Gatek, Jiri; Bendova, Marie; Vernerova, Zdenka; Kovar, Jan; Soucek, Pavel

2017-01-01

Apoptosis plays a critical role in cancer cell survival and tumor development. We provide a hypothesis-generating screen for further research by exploring the expression profile and genetic variability of caspases (2, 3, 7, 8, 9, and 10) in breast carcinoma patients. This study addressed isoform-specific caspase transcript expression and genetic variability in regulatory sequences of caspases 2 and 9. Gene expression profiling was performed by quantitative real-time PCR in tumor and paired non-malignant tissues of two independent groups of patients. Genetic variability was determined by high resolution melting, allelic discrimination, and sequencing analysis in tumor and peripheral blood lymphocyte DNA of the patients. CASP3 A+B and S isoforms were over-expressed in tumors of both patient groups. The CASP9 transcript was down-regulated in tumors of both groups of patients and significantly associated with expression of hormonal receptors and with the presence of rs4645978-rs2020903-rs4646034 haplotype in the CASP9 gene. Patients with a low intratumoral CASP9A/B isoform expression ratio (predicted to shift equilibrium towards anti-apoptotic isoform) subsequently treated with adjuvant chemotherapy had a significantly shorter disease-free survival than those with the high ratio (p=0.04). Inheritance of CC genotype of rs2020903 in CASP9 was associated with progesterone receptor expression in tumors (p=0.003). Genetic variability in CASP9 and expression of its splicing variants present targets for further study.

Relations between mental health team characteristics and work role performance.

PubMed

Fleury, Marie-Josée; Grenier, Guy; Bamvita, Jean-Marie; Farand, Lambert

2017-01-01

Effective mental health care requires a high performing, interprofessional team. Among 79 mental health teams in Quebec (Canada), this exploratory study aims to 1) determine the association between work role performance and a wide range of variables related to team effectiveness according to the literature, and to 2) using structural equation modelling, assess the covariance between each of these variables as well as the correlation with other exogenous variables. Work role performance was measured with an adapted version of a work role questionnaire. Various independent variables including team manager characteristics, user characteristics, team profiles, clinical activities, organizational culture, network integration strategies and frequency/satisfaction of interactions with other teams or services were analyzed under the structural equation model. The later provided a good fit with the data. Frequent use of standardized procedures and evaluation tools (e.g. screening and assessment tools for mental health disorders) and team manager seniority exerted the most direct effect on work role performance. While network integration strategies had little effect on work role performance, there was a high covariance between this variable and those directly affecting work role performance among mental health teams. The results suggest that the mental healthcare system should apply standardized procedures and evaluation tools and, to a lesser extent, clinical approaches to improve work role performance in mental health teams. Overall, a more systematic implementation of network integration strategies may contribute to improved work role performance in mental health care.

Rocky Mountain hydroclimate: Holocene variability and the role of insolation, ENSO, and the North American Monsoon

USGS Publications Warehouse

Anderson, Lesleigh

2012-01-01

Over the period of instrumental records, precipitation maximum in the headwaters of the Colorado Rocky Mountains has been dominated by winter snow, with a substantial degree of interannual variability linked to Pacific ocean–atmosphere dynamics. High-elevation snowpack is an important water storage that is carefully observed in order to meet increasing water demands in the greater semi-arid region. The purpose here is to consider Rocky Mountain water trends during the Holocene when known changes in earth's energy balance were caused by precession-driven insolation variability. Changes in solar insolation are thought to have influenced the variability and intensity of the El Niño Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and North American Monsoon and the seasonal precipitation balance between rain and snow at upper elevations. Holocene records are presented from two high elevation lakes located in northwest Colorado that document decade-to-century scale precipitation seasonality for the past ~ 7000 years. Comparisons with sub-tropical records of ENSO indicate that the snowfall-dominated precipitation maxima developed ~ 3000 and 4000 years ago, coincident with evidence for enhanced ENSO/PDO dynamics. During the early-to-mid Holocene the records suggest a more monsoon affected precipitation regime with reduced snowpack, more rainfall, and net moisture deficits that were more severe than recent droughts. The Holocene perspective of precipitation indicates a far broader range of variability than that of the past century and highlights the non-linear character of hydroclimate in the U.S. west.

Original method to compute epipoles using variable homography: application to measure emergent fibers on textile fabrics

NASA Astrophysics Data System (ADS)

Xu, Jun; Cudel, Christophe; Kohler, Sophie; Fontaine, Stéphane; Haeberlé, Olivier; Klotz, Marie-Louise

2012-04-01

Fabric's smoothness is a key factor in determining the quality of finished textile products and has great influence on the functionality of industrial textiles and high-end textile products. With popularization of the zero defect industrial concept, identifying and measuring defective material in the early stage of production is of great interest to the industry. In the current market, many systems are able to achieve automatic monitoring and control of fabric, paper, and nonwoven material during the entire production process, however online measurement of hairiness is still an open topic and highly desirable for industrial applications. We propose a computer vision approach to compute epipole by using variable homography, which can be used to measure emergent fiber length on textile fabrics. The main challenges addressed in this paper are the application of variable homography on textile monitoring and measurement, as well as the accuracy of the estimated calculation. We propose that a fibrous structure can be considered as a two-layer structure, and then we show how variable homography combined with epipolar geometry can estimate the length of the fiber defects. Simulations are carried out to show the effectiveness of this method. The true length of selected fibers is measured precisely using a digital optical microscope, and then the same fibers are tested by our method. Our experimental results suggest that smoothness monitored by variable homography is an accurate and robust method of quality control for important industrial fabrics.

Using variable homography to measure emergent fibers on textile fabrics

NASA Astrophysics Data System (ADS)

Xu, Jun; Cudel, Christophe; Kohler, Sophie; Fontaine, Stéphane; Haeberlé, Olivier; Klotz, Marie-Louise

2011-07-01

A fabric's smoothness is a key factor to determine the quality of textile finished products and has great influence on the functionality of industrial textiles and high-end textile products. With popularization of the 'zero defect' industrial concept, identifying and measuring defective material in the early stage of production is of great interest for the industry. In the current market, many systems are able to achieve automatic monitoring and control of fabric, paper, and nonwoven material during the entire production process, however online measurement of hairiness is still an open topic and highly desirable for industrial applications. In this paper we propose a computer vision approach, based on variable homography, which can be used to measure the emergent fiber's length on textile fabrics. The main challenges addressed in this paper are the application of variable homography to textile monitoring and measurement, as well as the accuracy of the estimated calculation. We propose that a fibrous structure can be considered as a two-layer structure and then show how variable homography can estimate the length of the fiber defects. Simulations are carried out to show the effectiveness of this method to measure the emergent fiber's length. The true lengths of selected fibers are measured precisely using a digital optical microscope, and then the same fibers are tested by our method. Our experimental results suggest that smoothness monitored by variable homography is an accurate and robust method for quality control of important industrially fabrics.

Relations between mental health team characteristics and work role performance

PubMed Central

Grenier, Guy; Bamvita, Jean-Marie; Farand, Lambert

2017-01-01

Effective mental health care requires a high performing, interprofessional team. Among 79 mental health teams in Quebec (Canada), this exploratory study aims to 1) determine the association between work role performance and a wide range of variables related to team effectiveness according to the literature, and to 2) using structural equation modelling, assess the covariance between each of these variables as well as the correlation with other exogenous variables. Work role performance was measured with an adapted version of a work role questionnaire. Various independent variables including team manager characteristics, user characteristics, team profiles, clinical activities, organizational culture, network integration strategies and frequency/satisfaction of interactions with other teams or services were analyzed under the structural equation model. The later provided a good fit with the data. Frequent use of standardized procedures and evaluation tools (e.g. screening and assessment tools for mental health disorders) and team manager seniority exerted the most direct effect on work role performance. While network integration strategies had little effect on work role performance, there was a high covariance between this variable and those directly affecting work role performance among mental health teams. The results suggest that the mental healthcare system should apply standardized procedures and evaluation tools and, to a lesser extent, clinical approaches to improve work role performance in mental health teams. Overall, a more systematic implementation of network integration strategies may contribute to improved work role performance in mental health care. PMID:28991923

Dedifferentiated Chondrosarcoma of the Larynx.

PubMed

Fidai, Shiraz S; Ginat, Daniel T; Langerman, Alexander J; Cipriani, Nicole A

2016-09-01

Primary dedifferentiated chondrosarcoma occurring in the larynx is a rare head and neck malignancy. The cases reported in the literature suggest male gender predilection and variable clinical outcomes ranging from disease-free survival to disease-related death. Although a calcified matrix is suggestive of chondrosarcoma, the dedifferentiated component is not readily appreciated on conventional imaging modalities and thorough tissue sampling is necessary for confirming the diagnosis. Histologically, there is an abrupt transition from a well-differentiated chondrosarcoma to a high-grade spindle cell component, which can show focal heterologous differentiation. These features are exemplified in this sine qua non radiology-pathology correlation article.

Built environment analysis for road traffic hotspot locations in Moshi, Tanzania.

PubMed

Waldon, Meredith; Ibingira, Treasure Joelson; de Andrade, Luciano; Mmbaga, Blandina T; Vissoci, João Ricardo N; Mvungi, Mark; Staton, Catherine A

2018-02-08

Road traffic injuries (RTIs) cause significant morbidity and mortality in low- and middle-income countries. Investigation of high risk areas for RTIs is needed to guide improvements. This study provides built environmental analysis of road traffic crash hotspots within Moshi, Tanzania. Spatial analysis of police data identified 36 hotspots. Qualitative comparative analysis revealed 40% of crash sites were on local roads without night lighting and increased motorcycle density. Paved narrow roads represented 26% of hotspots and 13% were unpaved roads with uneven roadsides. Roadside unevenness was more predominate in low risk [n = 19, (90.5%)] than high risk sites [n = 7 (46.7%)]. Both low [n = 6 (28.6%)] and high risk [n = 1 (6.7%)] sites had minimal signage. All sites had informal pedestrian pathways. Little variability between risk sites suggests hazardous conditions are widespread. Findings suggest improvement in municipal infrastructure, signage and enforcement is needed to reduce RTI burden.

Beyond the NAO: Dynamics and Precipitation Implications of the Azores High Since AD 800

NASA Astrophysics Data System (ADS)

Thatcher, D.; Wanamaker, A. D.; Denniston, R. F.; Asmerom, Y.; Ummenhofer, C.; Polyak, V. J.; Haws, J.; Gillikin, D. P.

2016-12-01

Atmospheric circulation in the North Atlantic region during the last millennium, particularly the state of the North Atlantic Oscillation (NAO), a system closely tied to regional precipitation dynamics, remains the subject of considerable debate in both proxy- and model-based studies. It has been suggested that the winter NAO was in a persistently positive state during the Medieval Climate Anomaly (MCA; AD 850-1250), resulting in increased precipitation across much of northern Europe and decreased rainfall across Iberia. However, besides changes in atmospheric circulation and precipitation dynamics that could be associated with an altered mean state of the NAO, relatively little attention has been given to atmospheric dynamics, namely the intensity and location, of the subtropical high system (Azores High, the southern node of the NAO) in driving hydroclimate in Iberia. Presented here is a continuous, precisely dated, and sub-decadally-resolved stalagmite isotopic and elemental time series from Buraca Gloriosa (BG) cave, western Portugal, situated within the center of the Azores High at the southern node of the NAO, which preserves evidence of regional hydroclimate from approximately AD 800 to the present. Stalagmite oxygen and carbon isotopic values and magnesium/calcium ratios primarily reflect effective moisture and reveal generally dry conditions during the MCA with a rapid shift to wetter conditions during the Little Ice Age (LIA; AD 1250-1850) at this location. Our proxy data reveal that substantial short-term hydroclimate variability characterized the last 1200 years. They support the hypothesis that while an intensified, semi-persistent subtropical high (and likely positive NAO state) characterized much of the MCA, the NAO remained variable over this time period. Climate model results also suggest that the Azores High pressure system both migrated southward and weakened from the MCA into the LIA.

The variability of methane, nitrous oxide and sulfur hexafluoride in Northeast India

NASA Astrophysics Data System (ADS)

Ganesan, A. L.; Chatterjee, A.; Prinn, R. G.; Harth, C. M.; Salameh, P. K.; Manning, A. J.; Hall, B. D.; Mühle, J.; Meredith, L. K.; Weiss, R. F.; O'Doherty, S.; Young, D.

2013-06-01

High-frequency atmospheric measurements of methane (CH4), nitrous oxide (N2O) and sulfur hexafluoride (SF6) from Darjeeling, India are presented from December 2011 (CH4)/March 2012 (N2O and SF6) through February 2013. These measurements were made on a gas chromatograph equipped with a flame ionization detector and electron capture detector and were calibrated on the Tohoku University, the Scripps Institution of Oceanography (SIO)-98 and SIO-2005 scales for CH4, N2O and SF6, respectively. The observations show large variability and frequent pollution events in CH4 and N2O mole fractions, suggesting significant sources in the regions sampled by Darjeeling throughout the year. In contrast, SF6 mole fractions show little variability and only occasional pollution episodes, likely due to weak sources in the region. Simulations using the Numerical Atmospheric dispersion Modelling Environment (NAME) particle dispersion model suggest that many of the enhancements in the three gases result from the transport of pollutants from the densely populated Indo-Gangetic plains of India to Darjeeling. The meteorology of the region varies considerably throughout the year from Himalayan flows in the winter to the strong South Asian summer monsoon. The model is consistent in simulating a diurnal cycle in CH4 and N2O mole fractions that is present during the winter but absent in the summer and suggests that the signals measured at Darjeeling are dominated by large scale (~100 km) flows rather than local (<10 km) flows.

The variability of methane, nitrous oxide and sulfur hexafluoride in Northeast India

NASA Astrophysics Data System (ADS)

Ganesan, A. L.; Chatterjee, A.; Prinn, R. G.; Harth, C. M.; Salameh, P. K.; Manning, A. J.; Hall, B. D.; Mühle, J.; Meredith, L. K.; Weiss, R. F.; O'Doherty, S.; Young, D.

2013-11-01

High-frequency atmospheric measurements of methane (CH4), nitrous oxide (N2O) and sulfur hexafluoride (SF6) from Darjeeling, India are presented from December 2011 (CH4)/March 2012 (N2O and SF6) through February 2013. These measurements were made on a gas chromatograph equipped with a flame ionization detector and electron capture detector, and were calibrated on the Tohoku University, the Scripps Institution of Oceanography (SIO)-98 and SIO-2005 scales for CH4, N2O and SF6, respectively. The observations show large variability and frequent pollution events in CH4 and N2O mole fractions, suggesting significant sources in the regions sampled by Darjeeling throughout the year. By contrast, SF6 mole fractions show little variability and only occasional pollution episodes, likely due to weak sources in the region. Simulations using the Numerical Atmospheric dispersion Modelling Environment (NAME) particle dispersion model suggest that many of the enhancements in the three gases result from the transport of pollutants from the densely populated Indo-Gangetic Plains of India to Darjeeling. The meteorology of the region varies considerably throughout the year from Himalayan flows in the winter to the strong south Asian summer monsoon. The model is consistent in simulating a diurnal cycle in CH4 and N2O mole fractions that is present during the winter but absent in the summer and suggests that the signals measured at Darjeeling are dominated by large-scale (~100 km) flows rather than local (<10 km) flows.

Weather extremes and the Romans - A marine palynological perspective on Italian temperature and precipitation between 200 BC and 500 AD

NASA Astrophysics Data System (ADS)

Zonneveld, Karin; Clotten, Caroline; Chen, Liang

2015-04-01

Sediments of a tephra-dated marine sediment core located at the distal part of the Po-river discharge plume (southern Italy) have been studied with a three annual resolution. Based on the variability in the dinoflagellate cyst content detailed reconstructions have been established of variability in precipitation related river discharge rates and local air temperature. Furthermore about the variability in distort water quality has been reconstructed. We show that both precipitation and temperature signals vary in tune with cyclic changes in solar insolation. On top of these cyclic changes, short term extremes in temperature and precipitation can be observed that can be interpreted to reflect periods of local weather extremes. Comparison of our reconstructions with historical information suggest that times of high temperatures and maximal precipitation corresponds to the period of maximal expansion of the Roman Empire. We have strong indications that at this time discharge waters might have contained higher nutrient concentrations compared to previous and later time intervals suggesting anthropogenic influence of the water quality. First pilot-results suggest that the decrease in temperature reconstructed just after the "Roman Optimum" corresponds to an increase in numbers of armored conflicts between the Roman and German cultures. Furthermore we observe a resemblance in timing of short-term intervals with cold weather spells during the early so called "Dark-Age-Period" to correspond to epidemic/pandemic events in Europe.

Identification and characterization of a highly variable region in mitochondrial genomes of fusarium species and analysis of power generation from microbial fuel cells

NASA Astrophysics Data System (ADS)

Hamzah, Haider Mousa

In the microbial fuel cell (MFC) project, power generation from Shewanella oneidensis MR-1 was analyzed looking for a novel system for both energy generation and sustainability. The results suggest the possibility of generating electricity from different organic substances, which include agricultural and industrial by-products. Shewanella oneidensis MR-1 generates usable electrons at 30°C using both submerged and solid state cultures. In the MFC biocathode experiment, most of the CO2 generated at the anodic chamber was converted into bicarbonate due the activity of carbonic anhydrase (CA) of the Gluconobacter sp.33 strain. These findings demonstrate the possibility of generation of electricity while at the same time allowing the biomimetic sequestration of CO2 using bacterial CA. In the mitochondrial genomes project, the filamentous fungal species Fusarium oxysporum was used as a model. This species causes wilt of several important agricultural crops. A previous study revealed that a highly variable region (HVR) in the mitochondrial DNA (mtDNA) of three species of Fusarium contained a large, variable unidentified open reading frame (LV-uORF). Using specific primers for two regions of the LV-uORF, six strains were found to contain the ORF by PCR and database searches identified 18 other strains outside of the Fusarium oxysporum species complex. The LV-uORF was also identified in three isolates of the F. oxysporum species complex. Interestingly, several F. oxysporum isolates lack the LV-uORF and instead contain 13 ORFs in the HVR, nine of which are unidentified. The high GC content and codon usage of the LV-uORF indicate that it did not co-evolve with other mt genes and was horizontally acquired and was introduced to the Fusarium lineage prior to speciation. The nonsynonymous/synonymous (dN/dS) ratio of the LV-uORFs (0.43) suggests it is under purifying selection and the putative polypeptide is predicted to be located in the mitochondrial membrane. Growth assays indicate that F. oxysporum strains containing the LV-uORF are able to tolerate high concentrations of zinc chloride, whereas those having the alternative HVR configuration are inhibited. This work suggests that fungal mitochondria can acquire additional genes and possibly novel functions and will guide studies that aim to assess the functional roles of hypothetical mitochondrial ORFs in filamentous fungi.

SU-F-R-30: Interscanner Variability of Radiomics Features in Computed Tomography (CT) Using a Standard ACR Phantom

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

Shafiq ul Hassan, M; Zhang, G; Moros, E

2016-06-15

Purpose: A simple approach to investigate Interscanner variability of Radiomics features in computed tomography (CT) using a standard ACR phantom. Methods: The standard ACR phantom was scanned on CT scanners from three different manufacturers. Scanning parameters of 120 KVp, 200 mA were used while slice thickness of 3.0 mm on two scanners and 3.27 mm on third scanner was used. Three spherical regions of interest (ROI) from water, medium density and high density inserts were contoured. Ninety four Radiomics features were extracted using an in-house program. These features include shape (11), intensity (22), GLCM (26), GLZSM (11), RLM (11), andmore » NGTDM (5) and 8 fractal dimensions features. To evaluate the Interscanner variability across three scanners, a coefficient of variation (COV) is calculated for each feature group. Each group is further classified according to the COV- by calculating the percentage of features in each of the following categories: COV less than 2%, between 2 and 10% and greater than 10%. Results: For all feature groups, similar trend was observed for three different inserts. Shape features were the most robust for all scanners as expected. 70% of the shape features had COV <2%. For intensity feature group, 2% COV varied from 9 to 32% for three scanners. All features in four groups GLCM, GLZSM, RLM and NGTDM were found to have Interscanner variability ≥2%. The fractal dimensions dependence for medium and high density inserts were similar while it was different for water inserts. Conclusion: We concluded that even for similar scanning conditions, Interscanner variability across different scanners was significant. The texture features based on GLCM, GLZSM, RLM and NGTDM are highly scanner dependent. Since the inserts of the ACR Phantom are not heterogeneous in HU values suggests that matrix based 2nd order features are highly affected by variation in noise. Research partly funded by NIH/NCI R01CA190105-01.« less

Suitability of satellite derived and gridded sea surface temperature data sets for calibrating high-resolution marine proxy records

NASA Astrophysics Data System (ADS)

Ouellette, G., Jr.; DeLong, K. L.

2016-02-01

High-resolution proxy records of sea surface temperature (SST) are increasingly being produced using trace element and isotope variability within the skeletal materials of marine organisms such as corals, mollusks, sclerosponges, and coralline algae. Translating the geochemical variations within these organisms into records of SST requires calibration with SST observations using linear regression methods, preferably with in situ SST records that span several years. However, locations with such records are sparse; therefore, calibration is often accomplished using gridded SST data products such as the Hadley Center's HADSST (5º) and interpolated HADISST (1º) data sets, NOAA's extended reconstructed SST data set (ERSST; 2º), optimum interpolation SST (OISST; 1º), and Kaplan SST data sets (5º). From these data products, the SST used for proxy calibration is obtained for a single grid cell that includes the proxy's study site. The gridded data sets are based on the International Comprehensive Ocean-Atmosphere Data Set (ICOADS) and each uses different methods of interpolation to produce the globally and temporally complete data products except for HadSST, which is not interpolated but quality controlled. This study compares SST for a single site from these gridded data products with a high-resolution satellite-based SST data set from NOAA (Pathfinder; 4 km) with in situ SST data and coral Sr/Ca variability for our study site in Haiti to assess differences between these SST records with a focus on seasonal variability. Our results indicate substantial differences in the seasonal variability captured for the same site among these data sets on the order of 1-3°C. This analysis suggests that of the data products, high-resolution satellite SST best captured seasonal variability at the study site. Unfortunately, satellite SST records are limited to the past few decades. If satellite SST are to be used to calibrate proxy records, collecting modern, living samples is desirable.

Endorsement of formal leaders: an integrative model.

PubMed

Michener, H A; Lawler, E J

1975-02-01

This experiment develops an integrative, path-analytic model for the endorsement accorded formal leaders. The model contains four independent variables reflecting aspects of group structure (i.e., group success-failure, the payoff distribution, the degree of support by others members for the leader, and the vulnerability of the leader). Also included are two intervening variables reflecting perceptual processes (attributed competence and attributed fairness), and one dependent variable endorsement). The results indicate that endorsement is greater when the group's success is high, when the payoff distribution is flat rather than hierarchial, and when the leader is not vulnerable to removal from office. Other support had no significant impact on endorsement. Analyses further demonstrate that the effect of success-failure on endorsement is mediated by attributed competence, while the effect of the payoff distributed is mediated by attributed fairness. These results suggest that moral and task evaluations are distinct bases of endorsement.

Wind, Circulation, and Topographic Effects on Alongshore Phytoplankton Variability in the California Current

NASA Astrophysics Data System (ADS)

Fiechter, Jerome; Edwards, Christopher A.; Moore, Andrew M.

2018-04-01

A physical-biogeochemical model is used to produce a retrospective analysis at 3-km resolution of alongshore phytoplankton variability in the California Current during 1988-2010. The simulation benefits from downscaling a regional circulation reanalysis, which provides improved physical ocean state estimates in the high-resolution domain. The emerging pattern is one of local upwelling intensification in response to increased alongshore wind stress in the lee of capes, modulated by alongshore meanders in the geostrophic circulation. While stronger upwelling occurs near most major topographic features, substantial increases in phytoplankton biomass only ensue where local circulation patterns are conducive to on-shelf retention of upwelled nutrients. Locations of peak nutrient delivery and chlorophyll accumulation also exhibit interannual variability and trends noticeably larger than the surrounding shelf regions, thereby suggesting that long-term planktonic ecosystem response in the California Current exhibits a significant local scale (O(100 km)) alongshore component.

Interannual variability and climatic noise in satellite-observed outgoing longwave radiation

NASA Technical Reports Server (NTRS)

Short, D. A.; Cahalan, R. F.

1983-01-01

Upwelling-IR observations of the North Pacific by polar orbiters NOAA 3, 4, 5, and 6 and TIROS-N from 1974 to 1981 are analyzed statistically in terms of interannual variability (IAV) in monthly averages and climatic noise due to short-term weather fluctuations. It is found that although the daily variance in the observations is the same in summer and winter months, and although IAV in winter is smaller than that in summer, the climatic noise in winter is so much smaller that a greater fraction of winter anomalies are statistically significant. The smaller winter climatic noise level is shown to be due to shorter autocorrelation times. It is demonstrated that increasing averaging area does not reduce the climatic noise level, suggesting that continuing collection of high-resolution satellite IR data on a global basis is necessary if better models of short-term variability are to be constructed.

Tohono O'odham Monsoon Climatology

NASA Astrophysics Data System (ADS)

Ackerman, G.

2006-12-01

The North American monsoon is a summertime weather phenomenon that develops over the southwestern North America. For thousands of years the Tohono O'odham people of this area have depended on the associated rainy season (Jukiabig Masad) to grow traditional crops using runoff agriculture. Today, the high incidence of Type II diabetes among native people has prompted many to return to their traditional agricultural diets. Local monsoon onset dates and the North American Regional Reanalysis dataset were used to develop a 24-year Tohono O'odham Nation (TON) monsoon and pre-monsoon climatology that can be used as a tool for planning runoff agriculture. Using monsoon composite datasets, temporal and spatial correlations between antecedent period meteorological variables, monsoon onset dates and total monsoon precipitation were examined to identify variables that could be useful in predicting the onset and intensity of the monsoon. The results suggest additional research is needed to identify variables related to monsoon onset and intensity.

Variability in sperm form and function in the context of sperm competition risk in two Tupinambis lizards

PubMed Central

Blengini, Cecilia S; Sergio, Naretto; Gabriela, Cardozo; Giojalas, Laura C; Margarita, Chiaraviglio

2014-01-01

In polyandrous species, sperm morphometry and sperm velocity are under strong sexual selection. Although several hypotheses have been proposed to explain the role of sperm competition in sperm trait variation, this aspect is still poorly understood. It has been suggested that an increase in sperm competition pressure could reduce sperm size variation or produce a diversity of sperm to maximize male fertilization success. We aim at elucidating the variability of sperm morphometric traits and velocity in two Tupinambis lizards in the context of sperm competition risk. Sperm traits showed substantial variation at all levels examined: between species, among males within species, and within the ejaculate of individual males. Sperm velocity was found to be positively correlated with flagellum: midpiece ratio, with relatively longer flagella associated with faster sperm. Our results document high variability in sperm form and function in lizards. PMID:25505535

Polarization swings reveal magnetic energy dissipation in blazars

DOE PAGES

Zhang, Haocheng; Chen, Xuhui; Böttcher, Markus; ...

2015-05-01

The polarization signatures of blazar emissions are known to be highly variable. In addition to small fluctuations of the polarization angle around a mean value, large (≳ 180°) polarization angle swings are observed. We suggest that such phenomena can be interpreted as arising from light-travel-time effects within an underlying axisymmetric emission region. We present the first simultaneous fitting of the multi-wavelength spectrum, variability, and time-dependent polarization features of a correlated optical and gamma-ray flaring event of the prominent blazar 3C279, which was accompanied by a drastic change in its polarization signatures. This unprecedented combination of spectral, variability, and polarization informationmore » in a coherent physical model allows us to place stringent constraints on the particle acceleration and magnetic-field topology in the relativistic jet of a blazar, strongly favoring a scenario in which magnetic energy dissipation is the primary driver of the flare event.« less

Growth and variability in health plan premiums in the individual insurance market before the Affordable Care Act.

PubMed

Gruber, Jonathan

2014-06-01

Before we can evaluate the impact of the Affordable Care Act on health insurance premiums in the individual market, it is critical to understand the pricing trends of these premiums before the implementation of the law. Using rates of increase in the individual insurance market collected from state regulators, this issue brief documents trends in premium growth in the pre-ACA period. From 2008 to 2010, premiums grew by 10 percent or more per year. This growth was also highly variable across states, and even more variable across insurance plans within states. The study suggests that evaluating trends in premiums requires looking across a broad array of states and plans, and that policymakers must examine how present and future changes in premium rates compare with the more than 10 percent per year premium increases in the years preceding health reform.

Efficient Construction of Discrete Adjoint Operators on Unstructured Grids by Using Complex Variables

NASA Technical Reports Server (NTRS)

Nielsen, Eric J.; Kleb, William L.

2005-01-01

A methodology is developed and implemented to mitigate the lengthy software development cycle typically associated with constructing a discrete adjoint solver for aerodynamic simulations. The approach is based on a complex-variable formulation that enables straightforward differentiation of complicated real-valued functions. An automated scripting process is used to create the complex-variable form of the set of discrete equations. An efficient method for assembling the residual and cost function linearizations is developed. The accuracy of the implementation is verified through comparisons with a discrete direct method as well as a previously developed handcoded discrete adjoint approach. Comparisons are also shown for a large-scale configuration to establish the computational efficiency of the present scheme. To ultimately demonstrate the power of the approach, the implementation is extended to high temperature gas flows in chemical nonequilibrium. Finally, several fruitful research and development avenues enabled by the current work are suggested.

Efficient Construction of Discrete Adjoint Operators on Unstructured Grids Using Complex Variables

NASA Technical Reports Server (NTRS)

Nielsen, Eric J.; Kleb, William L.

2005-01-01

A methodology is developed and implemented to mitigate the lengthy software development cycle typically associated with constructing a discrete adjoint solver for aerodynamic simulations. The approach is based on a complex-variable formulation that enables straightforward differentiation of complicated real-valued functions. An automated scripting process is used to create the complex-variable form of the set of discrete equations. An efficient method for assembling the residual and cost function linearizations is developed. The accuracy of the implementation is verified through comparisons with a discrete direct method as well as a previously developed handcoded discrete adjoint approach. Comparisons are also shown for a large-scale configuration to establish the computational efficiency of the present scheme. To ultimately demonstrate the power of the approach, the implementation is extended to high temperature gas flows in chemical nonequilibrium. Finally, several fruitful research and development avenues enabled by the current work are suggested.

Understanding Empathy, Self-Esteem, and Adult Attachment in Sexual Offenders and Partner-Violent Men.

PubMed

Loinaz, Ismael; Sánchez, Luis Miguel; Vilella, Andrea

2018-02-01

The assessment and treatment of emotional variables is a priority in the rehabilitation of offenders. Although theoretical proposals suggest a clear relationship between violence and self-esteem, attachment, and empathy, the research carried out to date has reached contradictory results due mainly to differences in the measurements used, the reliability of self-reports, or even to problems with the definition of the constructs. The present study analyzed these three variables in a prison sample of sexual offenders ( n = 48) and partner-violent men ( n = 68), using the Interpersonal Reactivity Index, the Rape Empathy Measure, the Rosenberg Self-Esteem Scale, and the Adult Attachment Questionnaire. Results confirmed the low utility of nonspecific empathy, the predominance of high self-esteem, and the difficulty of identifying an insecure attachment. The implications of the use of these variables in the treatment of offenders, and the need to improve the assessment tools, are discussed.

Arctic Climate and Atmospheric Planetary Waves

NASA Technical Reports Server (NTRS)

Cavalieri, D. J.; Haekkinen, S.

2000-01-01

Analysis of a fifty-year record (1946-1995) of monthly-averaged sea level pressure data provides a link between the phases of planetary-scale sea level pressure waves and Arctic Ocean and ice variability. Results of this analysis show: (1) a breakdown of the dominant wave I pattern in the late 1960's, (2) shifts in the mean phase of waves 1 and 2 since this breakdown, (3) an eastward shift in the phases of both waves 1 and 2 during the years of simulated cyclonic Arctic Ocean circulation relative to their phases during the years of anticyclonic circulation, (4) a strong decadal variability of wave phase associated with simulated Arctic Ocean circulation changes. Finally, the Arctic atmospheric circulation patterns that emerge when waves 1 and 2 are in their extreme eastern and western positions suggest an alternative approach to determine significant forcing patterns of sea ice and high-latitude variability.

Genetic characterization of Colombian Bahman cattle using microsatellites markers.

PubMed

Gómez, Y M; Fernandez, M; Rivera, D; Gómez, G; Bernal, J E

2013-07-01

Genetic structure and diversity of 3789 animals of the Brahman breed from 23 Colombian regions were assessed. Considering the Brahman Zebu cattle as a single population, the multilocus test based on the HW equilibrium, shows significant differences (P < 0.001). Genetic characterization made on the cattle population allowed to examine the genetic variability, calculating a H(o) = 0.6621. Brahman population in Colombia was a small subdivision within populations (F(it) = 0.045), a geographic subdivision almost non-existent or low differentiation (F(st) = 0.003) and the F(is) calculated (0.042) indicates no detriment to the variability in the population, despite the narrow mating takes place or there is a force that causes the variability is sustained without inbreeding actually affect the cattle population. The outcomes of multivariate analyses, Bayesian inferences and interindividual genetic distances suggested that there is no genetic sub-structure in the population, because of the high rate of animal migration among regions.

Analysis of Aircraft, Radiosonde and Radar Observations in Cirrus Clouds Observed During FIRE II: The Interactions Between Environmental Structure, Turbulence and Cloud Microphysical Properties

NASA Technical Reports Server (NTRS)

Smith, Samantha A.; DelGenio, Anthony D.

1999-01-01

Ways to determine the turbulence intensity and the horizontal variability in cirrus clouds have been investigated using FIRE-II aircraft, radiosonde and radar data. Higher turbulence intensities were found within some, but not all, of the neutrally stratified layers. It was also demonstrated that the stability of cirrus layers with high extinction values decrease in time, possibly as a result of radiative destabilization. However, these features could not be directly related to each other in any simple manner. A simple linear relationship was observed between the amount of horizontal variability in the ice water content and its average value. This was also true for the extinction and ice crystal number concentrations. A relationship was also suggested between the variability in cloud depth and the environmental stability across the depth of the cloud layer, which requires further investigation.

Heart rate variability and pain: associations of two interrelated homeostatic processes.

PubMed

Appelhans, Bradley M; Luecken, Linda J

2008-02-01

Between-person variability in pain sensitivity remains poorly understood. Given a conceptualization of pain as a homeostatic emotion, we hypothesized inverse associations between measures of resting heart rate variability (HRV), an index of autonomic regulation of heart rate that has been linked to emotionality, and sensitivity to subsequently administered thermal pain. Resting electrocardiography was collected, and frequency-domain measures of HRV were derived through spectral analysis. Fifty-nine right-handed participants provided ratings of pain intensity and unpleasantness following exposure to 4 degrees C thermal pain stimulation, and indicated their thresholds for barely noticeable and moderate pain during three exposures to decreasing temperature. Greater low-frequency HRV was associated with lower ratings of 4 degrees C pain unpleasantness and higher thresholds for barely noticeable and moderate pain. High-frequency HRV was unrelated to measures of pain sensitivity. Findings suggest pain sensitivity is influenced by characteristics of a central homeostatic system also involved in emotion.

Higher locus coeruleus MRI contrast is associated with lower parasympathetic influence over heart rate variability

PubMed Central

Mather, Mara; Yoo, Hyun Joo; Clewett, David V.; Lee, Tae-Ho; Greening, Steven G.; Ponzio, Allison; Min, Jungwon; Thayer, Julian F.

2017-01-01

The locus coeruleus (LC) is a key node of the sympathetic nervous system and suppresses parasympathetic activity that would otherwise increase heart rate variability. In the current study, we examined whether LC-MRI contrast reflecting neuromelanin accumulation in the LC was associated with high-frequency heart rate variability (HF-HRV), a measure reflecting parasympathetic influences on the heart. Recent evidence indicates that neuromelanin, a byproduct of catecholamine metabolism, accumulates in the LC through young and mid adulthood, suggesting that LC-MRI contrast may be a useful biomarker of individual differences in habitual LC activation. We found that, across younger and older adults, greater LC-MRI contrast was negatively associated with HF-HRV during fear conditioning and spatial detection tasks. This correlation was not accounted for by individual differences in age or anxiety. These findings indicate that individual differences in LC structure relate to key cardiovascular parameters. PMID:28215623

2000 Years of Drought Variability in Inner Asia from Tree Rings

NASA Astrophysics Data System (ADS)

Hessl, A. E.; Pederson, N.; Anchukaitis, K. J.; Leland, C.; Byambasuren, O.; Nachin, B.; Andreu-Hayles, L.

2015-12-01

Understanding connections between climate, ecosystems, and society during historical and modern climatic transitions requires annual resolution records with high fidelity climate signals. In semi-arid regions, high temperatures are projected to increase the frequency, duration, and severity of droughts in coming decades. Between 1996-2014, Mongolia experienced an extended drought that coincided with a transition away from pastoralism as thousands of families lost their herds and migrated to informal urban settlements. Because Mongolia's climate is highly variable, it is difficult to place recent climatic extremes and associated social and ecological change in context without long records of climatic variability. Here we ask: how extreme was the 21st century drought in the last 2000 years? We present two 2000 year long tree-ring reconstructions of warm-season drought, derived from live and dead Siberian pine (Pinus sibirica) trees from two lava flows in central Mongolia. Trees growing on the lava today are stunted and widely spaced, occurring on microsites with little to no soil development. These trees are water-stressed and their radial growth is correlated with both soil water availability (scPDSI) and grassland productivity (Normalized Difference Vegetation Index (NDVI)). To contextualize the severity of recent droughts and to explore potential forcing factors, we compare recent drought persistence to the distribution of events in the past and perform long control runs of GFDL climate model. Our reconstructions, calibrated and validated on instrumental June-August scPDSI (1959-2009) account for >55% of the variability in the regional scPDSI when >70% of the annual rainfall occurs. Our tree-ring data combined with existing reconstructions of temperature, meteorological data, and model results suggest that the early 21st century drought was the hottest and one of the most persistent droughts in the last 2000 years. These dry conditions were occurred with reductions in NPP of grasslands and loss of lake area. Our results are consistent with model projections of warming in Inner Asia but suggest that future warming may overwhelm increases in precipitation leading to similar "heat droughts", with potentially severe ecological and social consequences for Mongolia.

Evidence for a respiratory component, similar to mammalian respiratory sinus arrhythmia, in the heart rate variability signal from the rattlesnake, Crotalus durissus terrificus.

PubMed

Campbell, Hamish A; Leite, Cleo A C; Wang, Tobias; Skals, Marianne; Abe, Augusto S; Egginton, Stuart; Rantin, F Tadeu; Bishop, Charles M; Taylor, Edwin W

2006-07-01

Autonomic control of heart rate variability and the central location of vagal preganglionic neurones (VPN) were examined in the rattlesnake (Crotalus durissus terrificus), in order to determine whether respiratory sinus arrhythmia (RSA) occurred in a similar manner to that described for mammals. Resting ECG signals were recorded in undisturbed snakes using miniature datalogging devices, and the presence of oscillations in heart rate (fh) was assessed by power spectral analysis (PSA). This mathematical technique provides a graphical output that enables the estimation of cardiac autonomic control by measuring periodic changes in the heart beat interval. At fh above 19 min(-1) spectra were mainly characterised by low frequency components, reflecting mainly adrenergic tonus on the heart. By contrast, at fh below 19 min(-1) spectra typically contained high frequency components, demonstrated to be cholinergic in origin. Snakes with a fh >19 min(-1) may therefore have insufficient cholinergic tonus and/or too high an adrenergic tonus acting upon the heart for respiratory sinus arrhythmia (RSA) to develop. A parallel study monitored fh simultaneously with the intraperitoneal pressures associated with lung inflation. Snakes with a fh<19 min(-1) exhibited a high frequency (HF) peak in the power spectrum, which correlated with ventilation rate (fv). Adrenergic blockade by propranolol infusion increased the variability of the ventilation cycle, and the oscillatory component of the fh spectrum broadened accordingly. Infusion of atropine to effect cholinergic blockade abolished this HF component, confirming a role for vagal control of the heart in matching fh and fv in the rattlesnake. A neuroanatomical study of the brainstem revealed two locations for vagal preganglionic neurones (VPN). This is consistent with the suggestion that generation of ventilatory components in the heart rate variability (HRV) signal are dependent on spatially distinct loci for cardiac VPN. Therefore, this study has demonstrated the presence of RSA in the HRV signal and a dual location for VPN in the rattlesnake. We suggest there to be a causal relationship between these two observations.

Spatiotemporal variation in heat-related out-of-hospital cardiac arrest during the summer in Japan.

PubMed

Onozuka, Daisuke; Hagihara, Akihito

2017-04-01

Although several studies have reported the impacts of extremely high temperature on cardiovascular diseases, few studies have investigated the spatiotemporal variation in the incidence of out-of-hospital cardiac arrest (OHCA) due to extremely high temperature in Japan. Daily OHCA data from 2005 to 2014 were acquired from all 47 prefectures of Japan. We used time-series Poisson regression analysis combined with a distributed lag non-linear model to assess the temporal variability in the effects of extremely high temperature on OHCA incidence in each prefecture, adjusted for time trends. Spatial variability in the relationships between extremely high temperature and OHCA between prefectures was estimated using a multivariate random-effects meta-analysis. We analyzed 166,496 OHCA cases of presumed cardiac origin occurring during the summer (June to September) that met the inclusion criteria. The minimum morbidity percentile (MMP) was the 51st percentile of temperature during the summer in Japan. The overall cumulative relative risk at the 99th percentile vs. the MMP over lags 0-10days was 1.21 (95% CI: 1.12-1.31). There was also a strong low temperature effect during the summer periods. No substantial difference in spatial or temporal variability was observed over the study period. Our study demonstrated spatiotemporal homogeneity in the risk of OHCA during periods of extremely high temperature between 2005 and 2014 in Japan. Our findings suggest that public health strategies for OHCA due to extremely high temperatures should be finely adjusted and should particularly account for the unchanging risk during the summer. Copyright © 2017 Elsevier B.V. All rights reserved.

Ice core evidence for a 20th century increase in surface mass balance in coastal Dronning Maud Land, East Antarctica

NASA Astrophysics Data System (ADS)

Philippe, Morgane; Tison, Jean-Louis; Fjøsne, Karen; Hubbard, Bryn; Kjær, Helle A.; Lenaerts, Jan T. M.; Drews, Reinhard; Sheldon, Simon G.; De Bondt, Kevin; Claeys, Philippe; Pattyn, Frank

2016-10-01

Ice cores provide temporal records of surface mass balance (SMB). Coastal areas of Antarctica have relatively high and variable SMB, but are under-represented in records spanning more than 100 years. Here we present SMB reconstruction from a 120 m-long ice core drilled in 2012 on the Derwael Ice Rise, coastal Dronning Maud Land, East Antarctica. Water stable isotope (δ18O and δD) stratigraphy is supplemented by discontinuous major ion profiles and continuous electrical conductivity measurements. The base of the ice core is dated to AD 1759 ± 16, providing a climate proxy for the past ˜ 250 years. The core's annual layer thickness history is combined with its gravimetric density profile to reconstruct the site's SMB history, corrected for the influence of ice deformation. The mean SMB for the core's entire history is 0.47 ± 0.02 m water equivalent (w.e.) a-1. The time series of reconstructed annual SMB shows high variability, but a general increase beginning in the 20th century. This increase is particularly marked during the last 50 years (1962-2011), which yields mean SMB of 0.61 ± 0.01 m w.e. a-1. This trend is compared with other reported SMB data in Antarctica, generally showing a high spatial variability. Output of the fully coupled Community Earth System Model (CESM) suggests that, although atmospheric circulation is the main factor influencing SMB, variability in sea surface temperatures and sea ice cover in the precipitation source region also explain part of the variability in SMB. Local snow redistribution can also influence interannual variability but is unlikely to influence long-term trends significantly. This is the first record from a coastal ice core in East Antarctica to show an increase in SMB beginning in the early 20th century and particularly marked during the last 50 years.

A drift-diffusion checkpoint model predicts a highly variable and growth-factor-sensitive portion of the cell cycle G1 phase.

PubMed

Jones, Zack W; Leander, Rachel; Quaranta, Vito; Harris, Leonard A; Tyson, Darren R

2018-01-01

Even among isogenic cells, the time to progress through the cell cycle, or the intermitotic time (IMT), is highly variable. This variability has been a topic of research for several decades and numerous mathematical models have been proposed to explain it. Previously, we developed a top-down, stochastic drift-diffusion+threshold (DDT) model of a cell cycle checkpoint and showed that it can accurately describe experimentally-derived IMT distributions [Leander R, Allen EJ, Garbett SP, Tyson DR, Quaranta V. Derivation and experimental comparison of cell-division probability densities. J. Theor. Biol. 2014;358:129-135]. Here, we use the DDT modeling approach for both descriptive and predictive data analysis. We develop a custom numerical method for the reliable maximum likelihood estimation of model parameters in the absence of a priori knowledge about the number of detectable checkpoints. We employ this method to fit different variants of the DDT model (with one, two, and three checkpoints) to IMT data from multiple cell lines under different growth conditions and drug treatments. We find that a two-checkpoint model best describes the data, consistent with the notion that the cell cycle can be broadly separated into two steps: the commitment to divide and the process of cell division. The model predicts one part of the cell cycle to be highly variable and growth factor sensitive while the other is less variable and relatively refractory to growth factor signaling. Using experimental data that separates IMT into G1 vs. S, G2, and M phases, we show that the model-predicted growth-factor-sensitive part of the cell cycle corresponds to a portion of G1, consistent with previous studies suggesting that the commitment step is the primary source of IMT variability. These results demonstrate that a simple stochastic model, with just a handful of parameters, can provide fundamental insights into the biological underpinnings of cell cycle progression.

The relationship between vertical teaming in science and student achievement as reported in the Academic Excellence Indicator System (AEIS) at selected public schools in Bexar County, Texas

NASA Astrophysics Data System (ADS)

Arteaga, Veronica Hernandez

The purpose of this study was to examine the relationship between vertical teaming in science and student achievement. This study compared student achievement of campuses implementing vertical teaming with schools that do not practice vertical teaming. In addition, this study explored the relationship between selected demographic variables and vertical teaming using Grade 5 Science TAKS results in the Academic Excellence Indicator System (AEIS). Campus demographic variables such as economically disadvantaged, minority students, English language learners, student mobility, and experienced teachers were researched. A call-out yielded 168 responses. With the exclusion of the 12 campuses, a total of 156 participating campuses from 18 traditional school districts remained. Campuses employing vertical teaming were self-identified on the basis of having implemented the process for two or more years. The gain in percent mastered for Science TAKS scores from 2004 to 2007 was used as the Science TAKS score variable. Results indicated that there was no significant difference in student achievement in science for campuses practicing vertical teaming and campuses that did not. The two-way ANOVA was used to measure the relationship between the independent variables (vertical teaming and campus demographic variables) on the dependent variable (student achievement on Science TAKS). The results suggested that campuses having low percentages of economically disadvantaged students statistically gained more on the Science TAKS than campuses that have high percentages of economically disadvantaged students irrespective of vertical teaming practices. In addition, campuses that have low percentages of minority students statistically gained more on the Science TAKS than campuses that have high percentages of minority students despite vertical teaming participation. Recommendations include districts, state, and federal agencies providing campuses with a high percent of economically disadvantaged students with more resources and more flexibility in using those resources. Recommendations for further study included a replication of the study that takes into account the degree of implementation of vertical teaming.