Ontogenetic patterns in the mechanisms of tolerance to herbivory in Plantago

PubMed Central

Barton, Kasey E.

2013-01-01

Background and Aims Herbivory and plant defence differ markedly among seedlings and juvenile and mature plants in most species. While ontogenetic patterns of chemical resistance have been the focus of much research, comparatively little is known about how tolerance to damage changes across ontogeny. Due to dramatic shifts in plant size, resource acquisition, stored reserves and growth, it was predicted that tolerance and related underlying mechanisms would differ among ontogenetic stages. Methods Ontogenetic patterns in the mechanisms of tolerance were investigated in Plantago lanceolata and P. major (Plantaginaceae) using the genetic sib-ship approach. Pot-grown plants were subjected to 50 % defoliation at the seedling, juvenile and mature stages and either harvested in the short-term to look at plasticity in growth and photosynthesis in response to damage or allowed to grow through seed maturation to measure phenology, shoot compensation and reproductive fitness. Key Results Tolerance to defoliation was high in P. lanceolata, but low in P. major, and did not vary among ontogenetic stages in either species. Mechanisms underlying tolerance did vary across ontogeny. In P. lanceolata, tolerance was significantly related to flowering (juveniles) and pre-damage shoot biomass (mature plants). In P. major, tolerance was significantly related to pre-damage root biomass (seedlings) and induction of non-photochemical quenching, a photosynthetic parameter (juveniles). Conclusions Biomass partitioning was very plastic in response to damage and showed associations with tolerance in both species, indicating a strong role in plant defence. In contrast, photosynthesis and phenology showed weaker responses to damage and were related to tolerance only in certain ontogenetic stages. This study highlights the pivotal role of ontogeny in plant defence and herbivory. Additional studies in more species are needed to determine how seedlings tolerate herbivory in general and whether mechanisms vary across ontogeny in consistent patterns. PMID:23589631

Examining Variation in Adolescent Bystanders' Responses to Bullying

ERIC Educational Resources Information Center

Waasdorp, Tracy Evian; Bradshaw, Catherine P.

2018-01-01

Latent class analysis was used to examine whether patterns of bystander responses varied as a function of both student- and school-level characteristics. Data from 18,863 high school students from 58 schools who "ever witnessed bullying" were used to identify five latent classes of bystander behavior. Three of the classes identified…

Carbon allocation and partitioning in aspen clones varying in sensitivity to tropospheric ozone

Treesearch

M.D. Coleman; R.E. Dickson; J.G. Isebrands; D.F. Karnosky

1995-01-01

Clones of aspen (Populus tremuloides Michx.) were identified that differ in biomass production in response to O3exposure. 14Carbon tracer studies were used to determine if the differences in biomass response were linked to shifts in carbon allocation and carbon partitioning patterns. Rooted cuttings from...

The Differentiation of Response Numerosities in the Pigeon

ERIC Educational Resources Information Center

Machado, Armando; Rodrigues, Paulo

2007-01-01

Two experiments examined how pigeons differentiate response patterns along the dimension of number. In Experiment 1, 5 pigeons received food after pecking the left key at least N times and then switching to the right key (Mechner's Fixed Consecutive Number schedule). Parameter N varied across conditions from 4 to 32. Results showed that run length…

Responses of arthropod populations to warming depend on latitude: evidence from urban heat islands.

PubMed

Youngsteadt, Elsa; Ernst, Andrew F; Dunn, Robert R; Frank, Steven D

2017-04-01

Biological effects of climate change are expected to vary geographically, with a strong signature of latitude. For ectothermic animals, there is systematic latitudinal variation in the relationship between climate and thermal performance curves, which describe the relationship between temperature and an organism's fitness. Here, we ask whether these documented latitudinal patterns can be generalized to predict arthropod responses to warming across mid- and high temperate latitudes, for taxa whose thermal physiology has not been measured. To address this question, we used a novel natural experiment consisting of a series of urban warming gradients at different latitudes. Specifically, we sampled arthropods from a single common street tree species across temperature gradients in four US cities, located from 35.8 to 42.4° latitude. We captured 6746 arthropods in 34 families from 111 sites that varied in summer average temperature by 1.7-3.4 °C within each city. Arthropod responses to warming within each city were characterized as Poisson regression coefficients describing change in abundance per °C for each family. Family responses in the two midlatitude cities were heterogeneous, including significantly negative and positive effects, while those in high-latitude cities varied no more than expected by chance within each city. We expected high-latitude taxa to increase in abundance with warming, and they did so in one of the two high-latitude cities; in the other, Queens (New York City), most taxa declined with warming, perhaps due to habitat loss that was correlated with warming in this city. With the exception of Queens, patterns of family responses to warming were consistent with predictions based on known latitudinal patterns in arthropod physiology relative to regional climate. Heterogeneous responses in midlatitudes may be ecologically disruptive if interacting taxa respond oppositely to warming. © 2016 John Wiley & Sons Ltd.

Biphasic Dose Response in Low Level Light Therapy – An Update

PubMed Central

Huang, Ying-Ying; Sharma, Sulbha K; Carroll, James; Hamblin, Michael R

2011-01-01

Low-level laser (light) therapy (LLLT) has been known since 1967 but still remains controversial due to incomplete understanding of the basic mechanisms and the selection of inappropriate dosimetric parameters that led to negative studies. The biphasic dose-response or Arndt-Schulz curve in LLLT has been shown both in vitro studies and in animal experiments. This review will provide an update to our previous (Huang et al. 2009) coverage of this topic. In vitro mediators of LLLT such as adenosine triphosphate (ATP) and mitochondrial membrane potential show biphasic patterns, while others such as mitochondrial reactive oxygen species show a triphasic dose-response with two distinct peaks. The Janus nature of reactive oxygen species (ROS) that may act as a beneficial signaling molecule at low concentrations and a harmful cytotoxic agent at high concentrations, may partly explain the observed responses in vivo. Transcranial LLLT for traumatic brain injury (TBI) in mice shows a distinct biphasic pattern with peaks in beneficial neurological effects observed when the number of treatments is varied, and when the energy density of an individual treatment is varied. Further understanding of the extent to which biphasic dose responses apply in LLLT will be necessary to optimize clinical treatments. PMID:22461763

A multiyear study of soil moisture patterns across agricultural and forested landscapes

NASA Astrophysics Data System (ADS)

Georgakakos, C. B.; Hofmeister, K.; O'Connor, C.; Buchanan, B.; Walter, T.

2017-12-01

This work compares varying spatial and temporal soil moisture patterns in wet and dry years between forested and agricultural landscapes. This data set spans 6 years (2012-2017) of snow-free soil moisture measurements across multiple watersheds and land covers in New York State's Finger Lakes region. Due to the relatively long sampling period, we have captured fluctuations in soil moisture dynamics across wetter, dryer, and average precipitation years. We can therefore analyze response of land cover types to precipitation under varying climatic and hydrologic conditions. Across the study period, mean soil moisture in forest soils was significantly drier than in agricultural soils, and exhibited a smaller range of moisture conditions. In the drought year of 2016, soil moisture at all sites was significantly drier compared to the other years. When comparing the effects of land cover and year on soil moisture, we found that land cover had a more significant influence. Understanding the difference in landscape soil moisture dynamics between forested and agricultural land will help predict watershed responses to changing precipitation patterns in the future.

Initial responses of forest understories to varying levels and patterns of green-tree retention.

Treesearch

Charles B. Halpern; Donald McKenzie; Shelley A. Evans; Douglas A. Maguire

2005-01-01

Timber harvest with "green-tree" retention has been adopted in many temperate and boreal forest ecosystems, reflecting growing appreciation for the ecological values of managed forests. On federal forest lands in the Pacific Northwest, standards and guidelines for green-tree retention have been adopted, but systematic assessments of ecosystem response have...

Response of Newly Established Slash Pine to Cultivation and Fertilization

Treesearch

A.E. Tiarks; J.D. Haywood

1981-01-01

Response of newly established slash pine to fertilization is increased if herbaceous plants are controlled. To find the amount of cultivation required in Louisiana, fertilized and unfertilized rows of planted pines were hand-hoed in a wedge-shaped pattern. By using this technique, the amount of cultivation was varied from none to complete. Slash pine growth was...

Comparative transcriptome and gene co-expression network analysis reveal genes and signaling pathways adaptively responsive to varied adverse stresses in the insect fungal pathogen, Beauveria bassiana.

PubMed

He, Zhangjiang; Zhao, Xin; Lu, Zhuoyue; Wang, Huifang; Liu, Pengfei; Zeng, Fanqin; Zhang, Yongjun

2018-01-01

Sensing, responding, and adapting to the surrounding environment are crucial for all living organisms to survive, proliferate, and differentiate in their biological niches. Beauveria bassiana is an economically important insect-pathogenic fungus which is widely used as a biocontrol agent to control a variety of insect pests. The fungal pathogen unavoidably encounters a variety of adverse environmental stresses and defense response from the host insects during application of the fungal agents. However, few are known about the transcription response of the fungus to respond or adapt varied adverse stresses. Here, we comparatively analyzed the transcriptome of B. bassiana in globe genome under the varied stationary-phase stresses including osmotic agent (0.8 M NaCl), high temperature (32 °C), cell wall-perturbing agent (Congo red), and oxidative agents (H 2 O 2 or menadione). Total of 12,412 reads were obtained, and mapped to the 6767 genes of the B. bassiana. All of these stresses caused transcription responses involved in basal metabolism, cell wall construction, stress response or cell rescue/detoxification, signaling transduction and gene transcription regulation, and likely other cellular processes. An array of genes displayed similar transcription patterns in response to at least two of the five stresses, suggesting a shared transcription response to varied adverse stresses. Gene co-expression network analysis revealed that mTOR signaling pathway, but not HOG1 MAP kinase pathway, played a central role in regulation the varied adverse stress responses, which was verified by RNAi-mediated knockdown of TOR1. Our findings provided an insight of transcription response and gene co-expression network of B. bassiana in adaptation to varied environments. Copyright © 2017 Elsevier Inc. All rights reserved.

Effects of Timber Harvest on River Food Webs: Physical, Chemical and Biological Responses

PubMed Central

Wootton, J. Timothy

2012-01-01

I compared physical, chemical and biological characteristics of nine rivers running through three timber harvest regimes to investigate the effects of land use on river ecosystems, to determine whether these corresponded to changes linked with downstream location, and to compare the response of different types of indicator variables. Physical variables changed with downstream location, but varied little with timber harvest. Most chemical variables increased strongly with timber harvest, but not with downstream location. Most biological variables did not vary systematically with either timber harvst or downstream location. Dissolved organic carbon did not vary with timber harvest or downstream location, but correlated positively with salmonid abundance. Nutrient manipulations revealed no general pattern of nutrient limitation with timber harvest or downstream location. The results suggest that chemical variables most reliably indicate timber harvest impact in these systems. The biological variables most relevant to human stakeholders were surprisingly insensitive to timber harvest, however, apparently because of decoupling from nutrient responses and unexpectedly weak responses by physical variables. PMID:22957030

Patterned light flash evoked short latency activity in the visual system of visually normal and in amblyopic subjects.

PubMed

Sjöström, A; Abrahamsson, M

1994-04-01

In a previous experimental study on anaesthetized cat it was shown that a short latency (35-40 ms) cortical potential changed polarity due to the presence or absence of a pattern in the flash stimulus. The results suggested one pathway of neuronal activation in the cortex to a pattern that was within the level of resolution and another to patterns that were not. It was implied that a similar difference in impulse transmission to pattern and non-pattern stimuli may be recorded in humans. The present paper describes recordings of the short-latency visual evoked response to varying light flash checkerboard pattern stimuli of high intensity in visually normal and amblyopic children and adults. When stimulating the normal eye a visual evoked response potential with a peak latency between 35 to 40 ms showed a polarity change to patterned compared to non-patterned stimulation. The visual evoked response resolution limit could be correlated to a visual acuity of 0.5 and below. In amblyopic eyes the shift in polarity was recorded at the acuity limit level. The latency of the pattern depending potential was increased in patients with amblyopia compared to normal, but not directly related to amblyopic degree. It is concluded that the short latency, visual evoked response that mainly represents the retino-geniculo-cortical activation may be used to estimate visual resolution below 0.5 in acuity level.(ABSTRACT TRUNCATED AT 250 WORDS)

Testing the linearity and independence assumptions of the generalized matching law for reinforcer magnitude: a residual meta-analysis.

PubMed

Cording, Jacinta R; McLean, Anthony P; Grace, Randolph C

2011-05-01

We conducted a residual meta-analysis to test the assumptions of the generalized matching law that effects of relative reinforcer magnitude on response allocation in concurrent schedules can be described by a power function and are independent from the effects of relative reinforcer rate. We identified five studies which varied magnitude ratios over at least four levels and six studies in which reinforcer rate and magnitude ratios were varied factorially. The generalized matching law provided a reasonably good description of the data, accounting for 77.1% and 90.1% of the variance in the two sets of studies. Results of polynomial regressions showed that there were no systematic patterns in pooled residuals as a function of predicted log response ratios for data sets in which relative magnitude was varied. For data sets in which relative rate and magnitude were varied factorially, there was a significant negative cubic pattern in the pooled residuals, suggesting that obtained response allocation was less extreme than predicted for conditions with extreme predicted values. However, subsequent analyses showed that this result was associated with results from conditions in one study in which the product of the rate and magnitude ratios was 63:1, and in which response allocation may have been attenuated by a ceiling effect. When data from these conditions were omitted, there were no significant components in the residuals. Although the number of available studies was small, results provide tentative support for the assumptions of the generalized matching law that effects of reinforcer magnitude ratios on choice can be described by a power function and are independent from reinforcer rate ratios. Copyright © 2011 Elsevier B.V. All rights reserved.

Seeing a straight line on a curved surface: decoupling of patterns from surfaces by single IT neurons

PubMed Central

Ratan Murty, N. Apurva

2016-01-01

We have no difficulty seeing a straight line drawn on a paper even when the paper is bent, but this inference is in fact nontrivial. Doing so requires either matching local features or representing the pattern after factoring out the surface shape. Here we show that single neurons in the monkey inferior temporal (IT) cortex show invariant responses to patterns across rigid and nonrigid changes of surfaces. We recorded neuronal responses to stimuli in which the pattern and the surrounding surface were varied independently. In a subset of neurons, we found pattern-surface interactions that produced similar responses to stimuli across congruent pattern and surface transformations. These interactions produced systematic shifts in curvature tuning of patterns when overlaid on convex and flat surfaces. Our results show that surfaces are factored out of patterns by single neurons, thereby enabling complex perceptual inferences. NEW & NOTEWORTHY We have no difficulty seeing a straight line on a curved piece of paper, but in fact, doing so requires decoupling the shape of the surface from the pattern itself. Here we report a novel form of invariance in the visual cortex: single neurons in monkey inferior temporal cortex respond similarly to congruent transformations of patterns and surfaces, in effect decoupling patterns from the surface on which they are overlaid. PMID:27733595

Graphic design of pinhole cameras

NASA Technical Reports Server (NTRS)

Edwards, H. B.; Chu, W. P.

1979-01-01

The paper describes a graphic technique for the analysis and optimization of pinhole size and focal length. The technique is based on the use of the transfer function of optical elements described by Scott (1959) to construct the transfer function of a circular pinhole camera. This transfer function is the response of a component or system to a pattern of lines having a sinusoidally varying radiance at varying spatial frequencies. Some specific examples of graphic design are presented.

The temporal representation of the delay of dynamic iterated rippled noise with positive and negative gain by single units in the ventral cochlear nucleus.

PubMed

Sayles, Mark; Winter, Ian Michael

2007-09-26

Spike trains were recorded from single units in the ventral cochlear nucleus of the anaesthetised guinea-pig in response to dynamic iterated rippled noise with positive and negative gain. The short-term running waveform autocorrelation functions of these stimuli show peaks at integer multiples of the time-varying delay when the gain is +1, and troughs at odd-integer multiples and peaks at even-integer multiples of the time-varying delay when the gain is -1. In contrast, the short-term autocorrelation of the Hilbert envelope shows peaks at integer multiples of the time-varying delay for both positive and negative gain stimuli. A running short-term all-order interspike interval analysis demonstrates the ability of single units to represent the modulated pitch contour in their short-term interval statistics. For units with low best frequency (approximate < or = 1.1 kHz) the temporal discharge pattern reflected the waveform fine structure regardless of unit classification (Primary-like, Chopper). For higher best frequency units the pattern of response varied according to unit type. Chopper units with best frequency approximate > or = 1.1 kHz responded to envelope modulation; showing no difference between their response to stimuli with positive and negative gain. Primary-like units with best frequencies in the range 1-3 kHz were still able to represent the difference in the temporal fine structure between dynamic rippled noise with positive and negative gain. No unit with a best frequency above 3 kHz showed a response to the temporal fine structure. Chopper units in this high frequency group showed significantly greater representation of envelope modulation relative to primary-like units with the same range of best frequencies. These results show that at the level of the cochlear nucleus there exists sufficient information in the time domain to represent the time-varying pitch associated with dynamic iterated rippled noise.

Can trait patterns along gradients predict plant community responses to climate change?

PubMed

Guittar, John; Goldberg, Deborah; Klanderud, Kari; Telford, Richard J; Vandvik, Vigdis

2016-10-01

Plant functional traits vary consistently along climate gradients and are therefore potential predictors of plant community response to climate change. We test this space-for-time assumption by combining a spatial gradient study with whole-community turf transplantation along temperature and precipitation gradients in a network of 12 grassland sites in Southern Norway. Using data on eight traits for 169 species and annual vegetation censuses of 235 turfs over 5 yr, we quantify trait-based responses to climate change by comparing observed community dynamics in transplanted turfs to field-parameterized null model simulations. Three traits related to species architecture (maximum height, number of dormant meristems, and ramet-ramet connection persistence) varied consistently along spatial temperature gradients and also correlated to changes in species abundances in turfs transplanted to warmer climates. Two traits associated with resource acquisition strategy (SLA, leaf area) increased along spatial temperature gradients but did not correlate to changes in species abundances following warming. No traits correlated consistently with precipitation. Our study supports the hypothesis that spatial associations between plant traits and broad-scale climate variables can be predictive of community response to climate change, but it also suggests that not all traits with clear patterns along climate gradients will necessarily influence community response to an equal degree. © 2016 by the Ecological Society of America.

Responses of Cells in the Midbrain Near-Response Area in Monkeys with Strabismus

PubMed Central

Das, Vallabh E.

2012-01-01

Purpose. To investigate whether neuronal activity within the supraoculomotor area (SOA—monosynaptically connected to medial rectus motoneurons and encode vergence angle) of strabismic monkeys was correlated with the angle of horizontal misalignment and therefore helps to define the state of strabismus. Methods. Single-cell neural activity was recorded from SOA neurons in two monkeys with exotropia as they performed eye movement tasks during monocular viewing. Results. Horizontal strabismus angle varied depending on eye of fixation (dissociated horizontal deviation) and the activity of SOA cells (n = 35) varied in correlation with the angle of strabismus. Both near-response (cells that showed larger firing rates for smaller angles of exotropia) and far-response (cells that showed lower firing rates for smaller angles of exotropia) cells were identified. SOA cells showed no modulation of activity with changes in conjugate eye position as tested during smooth-pursuit, thereby verifying that the responses were related to binocular misalignment. SOA cell activity was also not correlated with change in horizontal misalignment due to A-patterns of strabismus. Comparison of SOA population activity in strabismic animals and normal monkeys (described in the literature) show that both neural thresholds and neural sensitivities are altered in the strabismic animals compared with the normal animals. Conclusions. SOA cell activity is important in determining the state of horizontal strabismus, possibly by altering vergence tone in extraocular muscle. The lack of correlated SOA activity with changes in misalignment due to A/V patterns suggest that circuits mediating horizontal strabismus angle and those that mediate A/V patterns are different. PMID:22562519

Spatial and temporal patterns of floral scent emission in Dianthus inoxianus and electroantennographic responses of its hawkmoth pollinator.

PubMed

Balao, Francisco; Herrera, Javier; Talavera, Salvador; Dötterl, Stefan

2011-05-01

Scent emission is important in nocturnal pollination systems, and plant species pollinated by nocturnal insects often present characteristic odor compositions and temporal patterns of emission. We investigated the temporal (day/night; flower lifetime) and spatial (different flower parts, nectar) pattern of flower scent emission in nocturnally pollinated Dianthusinoxianus, and determined which compounds elicit physiological responses on the antennae of the sphingid pollinator Hyles livornica. The scent of D.inoxianus comprises 68 volatile compounds, but is dominated by aliphatic 2-ketones and sesquiterpenoids, which altogether make up 82% of collected volatiles. Several major and minor compounds elicit electrophysiological responses in the antennae of H. livornica. Total odor emission does not vary along day and night hours, and neither does along the life of the flower. However, the proportion of compounds eliciting physiological responses varies between day and night. All flower parts as well as nectar release volatiles. The scent of isolated flower parts is dominated by fatty acid derivatives, whereas nectar is dominated by benzenoids. Dissection (= damage) of flowers induced a ca. 20-fold increase in the rate of emission of EAD-active volatiles, especially aliphatic 2-ketones. We suggest that aliphatic 2-ketones might contribute to pollinator attraction in D. inoxianus, even though they have been attributed an insect repellent function in other plant species. We also hypothesize that the benzenoids in nectar may act as an honest signal ('nectar guide') for pollinators. Copyright © 2011 Elsevier Ltd. All rights reserved.

An integrated parasitology: Revealing the elephant through tradition and invention

USDA-ARS?s Scientific Manuscript database

The field of parasitology contributes to the elucidation of patterns and processes in evolution, ecology and biogeography, of fundamental importance across the biosphere, leading to a thorough understanding of biodiversity and varied responses to global change. Foundations from taxonomic and systema...

A Monte Carlo Simulation Investigating the Validity and Reliability of Ability Estimation in Item Response Theory with Speeded Computer Adaptive Tests

ERIC Educational Resources Information Center

Schmitt, T. A.; Sass, D. A.; Sullivan, J. R.; Walker, C. M.

2010-01-01

Imposed time limits on computer adaptive tests (CATs) can result in examinees having difficulty completing all items, thus compromising the validity and reliability of ability estimates. In this study, the effects of speededness were explored in a simulated CAT environment by varying examinee response patterns to end-of-test items. Expectedly,…

Normalization of neuronal responses in cortical area MT across signal strengths and motion directions

PubMed Central

Xiao, Jianbo; Niu, Yu-Qiong; Wiesner, Steven

2014-01-01

Multiple visual stimuli are common in natural scenes, yet it remains unclear how multiple stimuli interact to influence neuronal responses. We investigated this question by manipulating relative signal strengths of two stimuli moving simultaneously within the receptive fields (RFs) of neurons in the extrastriate middle temporal (MT) cortex. Visual stimuli were overlapping random-dot patterns moving in two directions separated by 90°. We first varied the motion coherence of each random-dot pattern and characterized, across the direction tuning curve, the relationship between neuronal responses elicited by bidirectional stimuli and by the constituent motion components. The tuning curve for bidirectional stimuli showed response normalization and can be accounted for by a weighted sum of the responses to the motion components. Allowing nonlinear, multiplicative interaction between the two component responses significantly improved the data fit for some neurons, and the interaction mainly had a suppressive effect on the neuronal response. The weighting of the component responses was not fixed but dependent on relative signal strengths. When two stimulus components moved at different coherence levels, the response weight for the higher-coherence component was significantly greater than that for the lower-coherence component. We also varied relative luminance levels of two coherently moving stimuli and found that MT response weight for the higher-luminance component was also greater. These results suggest that competition between multiple stimuli within a neuron's RF depends on relative signal strengths of the stimuli and that multiplicative nonlinearity may play an important role in shaping the response tuning for multiple stimuli. PMID:24899674

Evolution of structural diversity of trichothecene mycotoxins

USDA-ARS?s Scientific Manuscript database

Fungal secondary metabolites (SMs) are diverse in structure and biological activity. Most can be divided into families of analogs that share a core structure but vary in patterns of functional groups (substituents) attached to the core. Typically, fungal genes responsible for synthesis of the same S...

Varying Inundation Regimes Differentially Affect Natural and Sand-Amended Marsh Sediments

EPA Science Inventory

Climate change is altering sea-level rise rates and precipitation patterns worldwide. Coastal wetlands are vulnerable to these changes. System responses to stressors are important for resource managers and environmental stewards to understand in order to best manage them. Thin la...

Exercise effects on lipids in persons with varying dietary patterns - Does diet matter if they exercise? Responses in STRRIDE I

PubMed Central

Huffman, Kim M.; Hawk, Victoria H.; Henes, Sarah T.; Ocampo, Christine I.; Orenduff, Melissa C.; Slentz, Cris A.; Johnson, Johanna L.; Houmard, Joseph A.; Samsa, Gregory P.; Kraus, William E.; Bales, Connie W.

2012-01-01

Background The standard clinical approach for reducing cardiovascular disease risk due to dyslipidemia is to prescribe changes in diet and physical activity. The purpose of the current study was to determine if, across a range of dietary patterns, there were variable lipoprotein responses to an aerobic exercise training intervention. Methods Subjects were participants in the Studies of a Targeted Risk Reduction Intervention through Defined Exercise (STRRIDE I), a supervised exercise program in sedentary, overweight subjects randomized to 6 months of inactivity or one of 3 aerobic exercise programs. To characterize diet patterns observed during the study, we calculated a modified z-score that included intakes of total fat, saturated fat, trans fatty acids, cholesterol, omega-3 fatty acids and fiber as compared to the 2006 AHA diet recommendations. Linear models were used to evaluate relationships between diet patterns and exercise effects on lipoproteins/lipids. Results Independent of diet, exercise had beneficial effects on LDL-cholesterol particle number, LDL-cholesterol size, HDL-cholesterol, HDL-cholesterol size, and triglycerides (P<0.05 for all). However, having a diet pattern that closely adhered to AHA recommendations was not related to changes in these or any other serum lipids or lipoproteins in any of the exercise groups. Conclusions We found that even in sedentary individuals whose habitual diets vary in the extent of adherence to AHA dietary recommendations, a rigorous, supervised exercise intervention can achieve significant beneficial lipid effects. PMID:22795291

Masticatory loadings and cranial deformation in Macaca fascicularis: a finite element analysis sensitivity study.

PubMed

Fitton, L C; Shi, J F; Fagan, M J; O'Higgins, P

2012-07-01

Biomechanical analyses are commonly conducted to investigate how craniofacial form relates to function, particularly in relation to dietary adaptations. However, in the absence of corresponding muscle activation patterns, incomplete muscle data recorded experimentally for different individuals during different feeding tasks are frequently substituted. This study uses finite element analysis (FEA) to examine the sensitivity of the mechanical response of a Macaca fascicularis cranium to varying muscle activation patterns predicted via multibody dynamic analysis. Relative to the effects of varying bite location, the consequences of simulated variations in muscle activation patterns and of the inclusion/exclusion of whole muscle groups were investigated. The resulting cranial deformations were compared using two approaches; strain maps and geometric morphometric analyses. The results indicate that, with bite force magnitude controlled, the variations among the mechanical responses of the cranium to bite location far outweigh those observed as a consequence of varying muscle activations. However, zygomatic deformation was an exception, with the activation levels of superficial masseter being most influential in this regard. The anterior portion of temporalis deforms the cranial vault, but the remaining muscles have less profound effects. This study for the first time systematically quantifies the sensitivity of an FEA model of a primate skull to widely varying masticatory muscle activations and finds that, with the exception of the zygomatic arch, reasonable variants of muscle loading for a second molar bite have considerably less effect on cranial deformation and the resulting strain map than does varying molar bite point. The implication is that FEA models of biting crania will generally produce acceptable estimates of deformation under load as long as muscle activations and forces are reasonably approximated. In any one FEA study, the biological significance of the error in applied muscle forces is best judged against the magnitude of the effect that is being investigated. © 2012 The Authors. Journal of Anatomy © 2012 Anatomical Society.

Masticatory loadings and cranial deformation in Macaca fascicularis: a finite element analysis sensitivity study

PubMed Central

Fitton, L C; Shi, J F; Fagan, M J; O’Higgins, P

2012-01-01

Biomechanical analyses are commonly conducted to investigate how craniofacial form relates to function, particularly in relation to dietary adaptations. However, in the absence of corresponding muscle activation patterns, incomplete muscle data recorded experimentally for different individuals during different feeding tasks are frequently substituted. This study uses finite element analysis (FEA) to examine the sensitivity of the mechanical response of a Macaca fascicularis cranium to varying muscle activation patterns predicted via multibody dynamic analysis. Relative to the effects of varying bite location, the consequences of simulated variations in muscle activation patterns and of the inclusion/exclusion of whole muscle groups were investigated. The resulting cranial deformations were compared using two approaches; strain maps and geometric morphometric analyses. The results indicate that, with bite force magnitude controlled, the variations among the mechanical responses of the cranium to bite location far outweigh those observed as a consequence of varying muscle activations. However, zygomatic deformation was an exception, with the activation levels of superficial masseter being most influential in this regard. The anterior portion of temporalis deforms the cranial vault, but the remaining muscles have less profound effects. This study for the first time systematically quantifies the sensitivity of an FEA model of a primate skull to widely varying masticatory muscle activations and finds that, with the exception of the zygomatic arch, reasonable variants of muscle loading for a second molar bite have considerably less effect on cranial deformation and the resulting strain map than does varying molar bite point. The implication is that FEA models of biting crania will generally produce acceptable estimates of deformation under load as long as muscle activations and forces are reasonably approximated. In any one FEA study, the biological significance of the error in applied muscle forces is best judged against the magnitude of the effect that is being investigated. PMID:22690885

Temporal pattern of feeding response of Chaoborus larvae to starvation

Treesearch

Rakesh Minocha; James F. Haney

1986-01-01

The effect of starvation on the feeding rate of larval Chaoborus (Diptera. Chaoboridae) was investigated using Daphnia rosea as prey. The starvation period varied from 12 h to 22 days. The starved Chaoborus were individually incubated with 10 Daphnia under controlled light and temperature...

Regularities in eyewitness identification.

PubMed

Clark, Steven E; Howell, Ryan T; Davey, Sherrie L

2008-06-01

What do eyewitness identification experiments typically show? We address this question through a meta-analysis of 94 comparisons between target-present and target-absent lineups. The analyses showed that: (a) correct identifications and correct-nonidentifications were uncorrelated, (b) suspect identifications were more diagnostic with respect to the suspect's guilt or innocence than any other response, (c) nonidentifications were diagnostic of the suspect's innocence, (d) the diagnosticity of foil identifications depended on lineup composition, and (e) don't know responses were nondiagnostic with respect to guilt or innocence. Results of diagnosticity analyses for simultaneous and sequential lineups varied for full-sample versus direct-comparison analyses. Diagnosticity patterns also varied as a function of lineup composition. Theoretical, forensic, and legal implications are discussed.

Atherosclerotic plaque characterization by spatial and temporal speckle pattern analysis

NASA Astrophysics Data System (ADS)

Tearney, Guillermo J.; Bouma, Brett E.

2002-04-01

Improved methods are needed to identify the vulnerable coronary plaques responsible for acute myocardial infraction or sudden cardiac death. We describe a method for characterizing the structure and biomechanical properties of atherosclerotic plaques based on speckle pattern fluctuations. Near-field speckle images were acquired from five human aortic specimens ex vivo. The speckle decorrelation time constant varied significantly for vulnerable aortic plaques (τ = 40 ms) versus stable plaques (τ = 400 ms) and normal aorta (τ = 500 ms). These initial results indicate that different atherosclerotic plaque types may be distinguished by analysis of temporal and spatial speckle pattern fluctuations.

Relationship between BOLD amplitude and pattern classification of orientation-selective activity in the human visual cortex.

PubMed

Tong, Frank; Harrison, Stephenie A; Dewey, John A; Kamitani, Yukiyasu

2012-11-15

Orientation-selective responses can be decoded from fMRI activity patterns in the human visual cortex, using multivariate pattern analysis (MVPA). To what extent do these feature-selective activity patterns depend on the strength and quality of the sensory input, and might the reliability of these activity patterns be predicted by the gross amplitude of the stimulus-driven BOLD response? Observers viewed oriented gratings that varied in luminance contrast (4, 20 or 100%) or spatial frequency (0.25, 1.0 or 4.0 cpd). As predicted, activity patterns in early visual areas led to better discrimination of orientations presented at high than low contrast, with greater effects of contrast found in area V1 than in V3. A second experiment revealed generally better decoding of orientations at low or moderate as compared to high spatial frequencies. Interestingly however, V1 exhibited a relative advantage at discriminating high spatial frequency orientations, consistent with the finer scale of representation in the primary visual cortex. In both experiments, the reliability of these orientation-selective activity patterns was well predicted by the average BOLD amplitude in each region of interest, as indicated by correlation analyses, as well as decoding applied to a simple model of voxel responses to simulated orientation columns. Moreover, individual differences in decoding accuracy could be predicted by the signal-to-noise ratio of an individual's BOLD response. Our results indicate that decoding accuracy can be well predicted by incorporating the amplitude of the BOLD response into simple simulation models of cortical selectivity; such models could prove useful in future applications of fMRI pattern classification. Copyright © 2012 Elsevier Inc. All rights reserved.

Relationship between BOLD amplitude and pattern classification of orientation-selective activity in the human visual cortex

PubMed Central

Tong, Frank; Harrison, Stephenie A.; Dewey, John A.; Kamitani, Yukiyasu

2012-01-01

Orientation-selective responses can be decoded from fMRI activity patterns in the human visual cortex, using multivariate pattern analysis (MVPA). To what extent do these feature-selective activity patterns depend on the strength and quality of the sensory input, and might the reliability of these activity patterns be predicted by the gross amplitude of the stimulus-driven BOLD response? Observers viewed oriented gratings that varied in luminance contrast (4, 20 or 100%) or spatial frequency (0.25, 1.0 or 4.0 cpd). As predicted, activity patterns in early visual areas led to better discrimination of orientations presented at high than low contrast, with greater effects of contrast found in area V1 than in V3. A second experiment revealed generally better decoding of orientations at low or moderate as compared to high spatial frequencies. Interestingly however, V1 exhibited a relative advantage at discriminating high spatial frequency orientations, consistent with the finer scale of representation in the primary visual cortex. In both experiments, the reliability of these orientation-selective activity patterns was well predicted by the average BOLD amplitude in each region of interest, as indicated by correlation analyses, as well as decoding applied to a simple model of voxel responses to simulated orientation columns. Moreover, individual differences in decoding accuracy could be predicted by the signal-to-noise ratio of an individual's BOLD response. Our results indicate that decoding accuracy can be well predicted by incorporating the amplitude of the BOLD response into simple simulation models of cortical selectivity; such models could prove useful in future applications of fMRI pattern classification. PMID:22917989

Masked priming for the comparative evaluation of camouflage conspicuity.

PubMed

Brunyé, Tad T; Eddy, Marianna D; Cain, Matthew S; Hepfinger, Lisa B; Rock, Kathryn

2017-07-01

Human observer test and evaluation of camouflage patterns is critical for understanding relative pattern conspicuity against a range of background scenes. However, very few validated methodologies exist for this purpose, and those that do carry several limitations. Five experiments examined whether masked priming with a dot probe could be used to reliably differentiate camouflage patterns. In each experiment, participants were primed with a camouflaged target appearing on the left or right of the screen, and then made a speeded response to a dot probe appearing on the same (congruent) or different (incongruent) side. Across experiments we parametrically varied prime duration between 35, 42, 49, 56, and 63 ms. Results demonstrated that as prime duration increased, a response time disadvantage for incongruent trials emerged with certain camouflage patterns. Interestingly, the most conspicuous patterns showed behavioral differences at a relatively brief (49 ms) prime duration, whereas behavioral differences were only found at longer prime durations for less conspicuous patterns; this overall results pattern matched that predicted by a visual salience model. Together, we demonstrate the viability of masked priming for the test and evaluation of camouflage patterns, and correlated outcomes for saliency models and primed object processing. Published by Elsevier Ltd.

Operative team communication during simulated emergencies: Too busy to respond?

PubMed

Davis, W Austin; Jones, Seth; Crowell-Kuhnberg, Adrianna M; O'Keeffe, Dara; Boyle, Kelly M; Klainer, Suzanne B; Smink, Douglas S; Yule, Steven

2017-05-01

Ineffective communication among members of a multidisciplinary team is associated with operative error and failure to rescue. We sought to measure operative team communication in a simulated emergency using an established communication framework called "closed loop communication." We hypothesized that communication directed at a specific recipient would be more likely to elicit a check back or closed loop response and that this relationship would vary with changes in patients' clinical status. We used the closed loop communication framework to code retrospectively the communication behavior of 7 operative teams (each comprising 2 surgeons, anesthesiologists, and nurses) during response to a simulated, postanesthesia care unit "code blue." We identified call outs, check backs, and closed loop episodes and applied descriptive statistics and a mixed-effects negative binomial regression to describe characteristics of communication in individuals and in different specialties. We coded a total of 662 call outs. The frequency and type of initiation and receipt of communication events varied between clinical specialties (P < .001). Surgeons and nurses initiated fewer and received more communication events than anesthesiologists. For the average participant, directed communication increased the likelihood of check back by at least 50% (P = .021) in periods preceding acute changes in the clinical setting, and exerted no significant effect in periods after acute changes in the clinical situation. Communication patterns vary by specialty during a simulated operative emergency, and the effect of directed communication in eliciting a response depends on the clinical status of the patient. Operative training programs should emphasize the importance of quality communication in the period immediately after an acute change in the clinical setting of a patient and recognize that communication patterns and needs vary between members of multidisciplinary operative teams. Copyright © 2016 Elsevier Inc. All rights reserved.

Spectrum pattern resolution after noise exposure in a beluga whale, Delphinapterus leucas: Evoked potential study.

PubMed

Popov, Vladimir V; Nechaev, Dmitry I; Sysueva, Evgenia V; Rozhnov, Viatcheslav V; Supin, Alexander Ya

2015-07-01

Temporary threshold shift (TTS) and the discrimination of spectrum patterns after fatiguing noise exposure (170 dB re 1 μPa, 10 min duration) was investigated in a beluga whale, Delphinapterus leucas, using the evoked potential technique. Thresholds were measured using rhythmic (1000/s) pip trains of varying levels and recording the rhythmic evoked responses. Discrimination of spectrum patterns was investigated using rippled-spectrum test stimuli of various levels and ripple densities, recording the rhythmic evoked responses to ripple phase reversals. Before noise exposure, the greatest responses to rippled-spectrum probes were evoked by stimuli with a low ripple density with a decrease in the response magnitude occurring with an increasing ripple density. After noise exposure, both a TTS and a reduction of the responses to rippled-spectrum probes appeared and recovered in parallel. The reduction of the responses to rippled-spectrum probes was maximal for high-magnitude responses at low ripple densities and was negligible for low-magnitude responses at high ripple densities. It is hypothesized that the impacts of fatiguing sounds are not limited by increased thresholds and decreased sensitivity results in reduced ability to discriminate fine spectral content with the greatest impact on the discrimination of spectrum content that may carry the most obvious information about stimulus properties.

Patterns and Assumptions: The Keys to Understanding Organizational Cultures.

DTIC Science & Technology

1982-06-01

assumption of the Navaho Indians: 8 Experience shows that if one asks Navaho Indians about witchcraft , more than 70 per cent will give almost identical...verbal responses. The replies will vary only in this fashion: "Who told you to talk to me about witchcraft ?" "Who said that I knew anything about... witchcraft ?" "Why do you come to ask about this--who told--pou I knew about it?" Here one has a behavioral pattern of the explicit culture, for the structure

Experiential, Autonomic, and Neural Responses During Threat Anticipation Vary as a Function of Threat Intensity and Neuroticism

PubMed Central

Drabant, Emily M; Kuo, Janice R; Ramel, Wiveka; Blechert, Jens; Edge, Michael D; Cooper, Jeff R; Goldin, Philippe R; Hariri, Ahmad R; Gross, James J

2011-01-01

Anticipatory emotional responses play a crucial role in preparing individuals for impending challenges. They do this by triggering a coordinated set of changes in behavioral, autonomic, and neural response systems. In the present study, we examined the biobehavioral impact of varying levels of anticipatory anxiety, using a shock anticipation task in which unpredictable electric shocks were threatened and delivered to the wrist at variable intervals and intensities (safe, medium, strong). This permitted investigation of a dynamic range of anticipatory anxiety responses. In two studies, 95 and 51 healthy female participants, respectively, underwent this shock anticipation task while providing continuous ratings of anxiety experience and electrodermal responding (Study 1) and during fMRI BOLD neuroimaging (Study 2). Results indicated a step-wise pattern of responding in anxiety experience and electrodermal responses. Several brain regions showed robust responses to shock anticipation relative to safe trials, including the hypothalamus, periaqueductal gray, caudate, precentral gyrus, thalamus, insula, ventrolateral PFC, dorsomedial PFC, and ACC. A subset of these regions demonstrated a linear pattern of increased responding from safe to medium to strong trials, including the bilateral insula, ACC, and inferior frontal gyrus. These responses were modulated by individual differences in neuroticism, such that those high in neuroticism showed exaggerated anxiety experience across the entire task, and reduced brain activation from medium to strong trials in a subset of brain regions. These findings suggest that individual differences in neuroticism may influence sensitivity to anticipatory threat and provide new insights into the mechanism through which neuroticism may confer risk for developing anxiety disorders via dysregulated anticipatory responses. PMID:21093595

Hydrochemical responses among nested catchments of the Sleepers River Research Watershed.

NASA Astrophysics Data System (ADS)

Sebestyen, S. D.; Boyer, E. W.; Shanley, J. B.; Kendall, C.

2005-12-01

We are probing chemical and isotopic tracers of dissolved organic carbon (DOC) and nitrate over both space and time to determine how stream nutrient dynamics change with increasing basin size and differ with flow conditions. At the Sleepers River Research Watershed in northeastern Vermont, USA, 20 to 30 nested sub-basins that ranged in size from 3 to 11,000 ha were sampled repeatedly under baseflow conditions. These synoptic surveys showed a pattern of heterogeneity in headwaters that converged to a consistent response at larger basin sizes and is consistent with findings of other studies. In addition to characterizing spatial patterns under baseflow, we sampled rainfall and snowmelt events over a gradient of basin sizes to investigate scaling responses under different flow conditions. During high flow events, DOC and nitrate flushing responses varied among different basins where high-frequency event samples were collected. While the DOC and nitrate concentration patterns were similar at four headwater basins, the concentration responses of larger basins were markedly different in that the concentration patterns, flushing duration, and maximum concentrations were attenuated from headwaters to the largest basin. We are using these data to explore how flow paths and solute mixing aggregate. Overall, these results highlight the complexities of understanding spatial scaling issues in catchments and underscore the need to consider event responses of hydrology and chemistry among catchments.

Do short international layovers allow sufficient opportunity for pilots to recover?

PubMed

Lamond, Nicole; Petrilli, Renée M; Dawson, Drew; Roach, Gregory D

2006-01-01

For Australian pilots, short layovers (<40 h) are a feature of many international patterns. However, anecdotal reports suggest that flight crew members find patterns with short slips more fatiguing than those with a longer international layover, as they restrict the opportunity to obtain sufficient sleep. The current study aimed to determine whether pilots operating international patterns with short layovers have sufficient opportunity to recover prior to the inbound flight. Nineteen international pilots (ten captains, nine first officers) operating a direct return pattern from Australia to Los Angeles (LAX) with a short (n = 9) 9+/-0.8 h (mean+/-S.D) or long (n = 10) 62.2+/-0.9 h LAX layover wore an activity monitor and kept a sleep/duty diary during the pattern. Immediately before and after each flight, pilots completed a 5 min PalmPilot-based psychomotor vigilance task (Palm-PVT). Flights were of comparable duration outbound (3.5+/-0.6 h) and inbound (14.3+/-0.6 h) and timing. The amount of sleep obtained in-flight did not significantly vary as a function of layover length. However, pilots obtained significantly more sleep during the inbound (3.7+/-0.8 h) than the outbound flight (2.2+/-0.8 h). Pilots with the shorter layover obtained significantly less sleep in total during layover (14.0+/-2.7 h vs. 19.6+/-2.5), due to significantly fewer sleep periods (3.0+/-0.7 vs. 4.0+/-0.9). However, neither mean sleep duration nor the sleep obtained in the 24 h prior to the inbound flight significantly differed as a function of layover length. Response speed significantly varied across the pattern, and a significant interaction was also observed. For pilots with a short layover, response speed was significantly slower at the end of both the outbound and inbound flight, and prior to the inbound flight (i.e., at the end of layover), relative to response speed at the start of the pattern (pre-trip). Similarly, response speed for the longer layover was slower at the end of the outbound flight compared to pre-trip (approaching significance, p = 0.073). However, response speed at the beginning of the inbound flight was significantly faster than pre-trip and did not significantly differ from pre-trip at the end of the inbound flight. The data suggest that short slips (<40 h) do not allow pilots the opportunity to obtain sufficient sleep to reverse the effects of fatigue accumulated during the outbound flight. As a result, their response speed prior to the inbound flight is substantially slower than the response speed of flight crew with a longer layover.

Human Corneal Limbal-Epithelial Cell Response to Varying Silk Film Geometric Topography In Vitro

PubMed Central

Lawrence, Brian D.; Pan, Zhi; Liu, Aihong; Kaplan, David L.; Rosenblatt, Mark I.

2012-01-01

Silk fibroin films are a promising class of biomaterials that have a number of advantages for use in ophthalmic applications due to their transparent nature, mechanical properties and minimal inflammatory response upon implantation. Freestanding silk films with parallel line and concentric ring topographies were generated for in vitro characterization of human corneal limbal-epithelial (HCLE) cell response upon differing geometric patterned surfaces. Results indicated that silk film topography significantly affected initial HCLE culture substrate attachment, cellular alignment, cell-to-cell contact formation, actin cytoskeleton alignment, and focal adhesion (FA) localization. Most notably, parallel line patterned surfaces displayed a 36%–54% increase on average in initial cell attachment, which corresponded to an over 2-fold increase in FA localization when compared to other silk film surfaces and controls. In addition, distinct localization of FA formation was observed along the edges for all patterned silk film topographies. In conclusion, silk film feature topography appears to help direct corneal epithelial cell response and cytoskeleton development, especially in regards to FA distribution, in vitro. PMID:22705042

Social Reinforcement Delays in Free-Flying Honey Bees (Apis mellifera L.)

PubMed Central

Craig, David Philip Arthur; Grice, James W.; Varnon, Chris A.; Gibson, B.; Sokolowski, Michel B. C.; Abramson, Charles I.

2012-01-01

Free-flying honey bees (Apis mellifera L.) reactions were observed when presented with varying schedules of post-reinforcement delays of 0 s, 300 s, or 600 s. We measured inter-visit-interval, response length, inter-response-time, and response rate. Honey bees exposed to these post-reinforcement delay intervals exhibit one of several patterns compared to groups not encountering delays, and had longer inter-visit-intervals. We observed no group differences in inter-response time. Honey bees with higher response rates tended to not finish the experiment. The removal of the delay intervals increased response rates for those subjects that completed the trials. PMID:23056425

Exercise effects on lipids in persons with varying dietary patterns-does diet matter if they exercise? Responses in Studies of a Targeted Risk Reduction Intervention through Defined Exercise I.

PubMed

Huffman, Kim M; Hawk, Victoria H; Henes, Sarah T; Ocampo, Christine I; Orenduff, Melissa C; Slentz, Cris A; Johnson, Johanna L; Houmard, Joseph A; Samsa, Gregory P; Kraus, William E; Bales, Connie W

2012-07-01

The standard clinical approach for reducing cardiovascular disease risk due to dyslipidemia is to prescribe changes in diet and physical activity. The purpose of the current study was to determine if, across a range of dietary patterns, there were variable lipoprotein responses to an aerobic exercise training intervention. Subjects were participants in the STRRIDE I, a supervised exercise program in sedentary, overweight subjects randomized to 6 months of inactivity or 1 of 3 aerobic exercise programs. To characterize diet patterns observed during the study, we calculated a modified z-score that included intakes of total fat, saturated fat, trans fatty acids, cholesterol, omega-3 fatty acids, and fiber as compared with the 2006 American Heart Association diet recommendations. Linear models were used to evaluate relationships between diet patterns and exercise effects on lipoproteins/lipids. Independent of diet, exercise had beneficial effects on low-density lipoprotein cholesterol particle number, low-density lipoprotein cholesterol size, high-density lipoprotein cholesterol, high-density lipoprotein cholesterol size, and triglycerides (P < .05 for all). However, having a diet pattern that closely adhered to American Heart Association recommendations was not related to changes in these or any other serum lipids or lipoproteins in any of the exercise groups. We found that even in sedentary individuals whose habitual diets vary in the extent of adherence to AHA dietary recommendations, a rigorous, supervised exercise intervention can achieve significant beneficial lipid effects. Copyright © 2012 Mosby, Inc. All rights reserved.

Wireless sensing system for non-invasive monitoring of attributes of contents in a container

NASA Technical Reports Server (NTRS)

Woodard, Stanley E. (Inventor)

2010-01-01

A wireless sensing system monitors the level, temperature, magnetic permeability and electrical dielectric constant of a non-gaseous material in a container. An open-circuit electrical conductor is shaped to form a two-dimensional geometric pattern that can store and transfer electrical and magnetic energy. The conductor resonates in the presence of a time-varying magnetic field to generate a harmonic response. The conductor is mounted in an environmentally-sealed housing. A magnetic field response recorder wirelessly transmits the time-varying magnetic field to power the conductor, and wirelessly detects the harmonic response that is an indication of at least one of level of the material in the container, temperature of the material in the container, magnetic permeability of the material in the container, and dielectric constant of the material in the container.

In Situ Observational Constraints on GIA in Antarctica

NASA Astrophysics Data System (ADS)

Wilson, T. J.; Bevis, M. G.; Kendrick, E. C.; Konfal, S.; Dalziel, I. W.; Smalley, R.; Willis, M. J.; Wiens, D. A.; Heeszel, D. S.

2012-12-01

Geodetic and seismologic data sets have been acquired across a significant portion of Antarctica through deployment of autonomous, remote instrumentation by the Antarctic Network (ANET) project of the Polar Earth Observing Network (POLENET). Continuous GPS measurements of bedrock crustal motions are yielding a synoptic picture of vertical and horizontal crustal motion patterns from the Transantarctic Mountains to the Ellsworth-Whitmore Mountains and Marie Byrd Land regions. Vertical motion patterns are broadly compatible with predictions from current GIA models, but the magnitudes of the vertical motions are substantially lower than predicted. Slower rates of uplift due to GIA can be attributed to factors including errors in ice history, a superposed solid earth response to modern ice mass change, and/or the influence of laterally varying earth properties on the GIA response. Patterns of horizontal motions measured by ANET show that the role of laterally varying earth rheology is extremely important in Antarctica. Crustal motion vectors are closely aligned and document motion from East toward West Antarctica, in contradiction to ice sheet reconstructions placing maximum LGM ice mass loss in West Antarctica and GIA models that predict motions in the opposite direction. When compared to earth structure mapped by seismology, the horizontal crustal motions are consistently near-perpendicular to the very strong gradient in crust and mantle properties, perhaps the first confirmation of predictions from modeling studies that horizontal motions can be deflected or even reversed where such a lateral earth property exists. Accurate GIA models for Antarctica clearly require a laterally-varying earth model and tuning based on these new GPS and seismological constraints.

Meiobenthic communities in permanently open estuaries and open/closed coastal lagoons of Uruguay (Atlantic coast of South America)

NASA Astrophysics Data System (ADS)

Kandratavicius, N.; Muniz, P.; Venturini, N.; Giménez, L.

2015-09-01

This study aimed to determine if estuarine meiofaunal communities of Uruguay (South America) vary between permanently open estuaries and open/closed coastal lagoons, or if they respond to the sediment composition. In Uruguay, estuaries and coastal lagoons vary in the degree of connectivity to the sea and in the sediment composition; sediments in estuaries are characterized by fine-medium sands but sediments vary from lagoon to lagoon (either fine-medium or coarse sand). Taxa richness (total = 16) showed less temporal variability in lagoons than in estuaries, due to patterns of presence/absence of the less abundant taxa. However, no major response to habitat was found in the most abundant groups: polychaetes (6% of total fauna) were on average 5% more abundant in lagoons than in estuaries. Some level of zonation, within estuaries and lagoons, was found in the most abundant groups, nematodes (63% of total fauna) and copepods (15%) in response to medium and fine sands. In addition, sediment type modulated seasonal patterns in the frequency of presence/absence in ostracods, polychaetes and oligochaetes. For instance, in polychaetes and ostracods the increase in the frequency of absences, occurring from summer to winter, was stronger in lagoons and estuaries dominated by fine sands. The lagoon habitat appears to ameliorate the effects of unfavourable (winter) conditions in less abundant meiofaunal taxa. In summary, sediment fractions explain spatial patterns in the average abundance of organisms (e.g. nematodes) as well as the seasonal changes in frequency of presence/absence (e.g. polychaetes).

Dynamic response and transfer function of social systems: A neuro-inspired model of collective human activity patterns.

PubMed

Lymperopoulos, Ilias N

2017-10-01

The interaction of social networks with the external environment gives rise to non-stationary activity patterns reflecting the temporal structure and strength of exogenous influences that drive social dynamical processes far from an equilibrium state. Following a neuro-inspired approach, based on the dynamics of a passive neuronal membrane, and the firing rate dynamics of single neurons and neuronal populations, we build a state-of-the-art model of the collective social response to exogenous interventions. In this regard, we analyze online activity patterns with a view to determining the transfer function of social systems, that is, the dynamic relationship between external influences and the resulting activity. To this end, first we estimate the impulse response (Green's function) of collective activity, and then we show that the convolution of the impulse response with a time-varying external influence field accurately reproduces empirical activity patterns. To capture the dynamics of collective activity when the generating process is in a state of statistical equilibrium, we incorporate into the model a noisy input convolved with the impulse response function, thus precisely reproducing the fluctuations of stationary collective activity around a resting value. The outstanding goodness-of-fit of the model results to empirical observations, indicates that the model explains human activity patterns generated by time-dependent external influences in various socio-economic contexts. The proposed model can be used for inferring the temporal structure and strength of external influences, as well as the inertia of collective social activity. Furthermore, it can potentially predict social activity patterns. Copyright © 2017 Elsevier Ltd. All rights reserved.

Discrimination of speech stimuli based on neuronal response phase patterns depends on acoustics but not comprehension.

PubMed

Howard, Mary F; Poeppel, David

2010-11-01

Speech stimuli give rise to neural activity in the listener that can be observed as waveforms using magnetoencephalography. Although waveforms vary greatly from trial to trial due to activity unrelated to the stimulus, it has been demonstrated that spoken sentences can be discriminated based on theta-band (3-7 Hz) phase patterns in single-trial response waveforms. Furthermore, manipulations of the speech signal envelope and fine structure that reduced intelligibility were found to produce correlated reductions in discrimination performance, suggesting a relationship between theta-band phase patterns and speech comprehension. This study investigates the nature of this relationship, hypothesizing that theta-band phase patterns primarily reflect cortical processing of low-frequency (<40 Hz) modulations present in the acoustic signal and required for intelligibility, rather than processing exclusively related to comprehension (e.g., lexical, syntactic, semantic). Using stimuli that are quite similar to normal spoken sentences in terms of low-frequency modulation characteristics but are unintelligible (i.e., their time-inverted counterparts), we find that discrimination performance based on theta-band phase patterns is equal for both types of stimuli. Consistent with earlier findings, we also observe that whereas theta-band phase patterns differ across stimuli, power patterns do not. We use a simulation model of the single-trial response to spoken sentence stimuli to demonstrate that phase-locked responses to low-frequency modulations of the acoustic signal can account not only for the phase but also for the power results. The simulation offers insight into the interpretation of the empirical results with respect to phase-resetting and power-enhancement models of the evoked response.

Neuroendocrine abnormalities in hypothalamic amenorrhea: spectrum, stability, and response to neurotransmitter modulation.

PubMed

Perkins, R B; Hall, J E; Martin, K A

1999-06-01

To characterize the neuroendocrine patterns of abnormal GnRH secretion in hypothalamic amenorrhea (HA), 49 women with primary and secondary HA underwent frequent sampling of LH in a total of 72 baseline studies over 12-24 h. A subset of women participated in more than one study to address 1) the variability of LH pulse patterns over time; and 2) the impact of modulating opioid, dopaminergic, and adrenergic tone on LH secretory patterns. The frequency and amplitude of LH secretion was compared with that seen in the early follicular phase (EFP) of normally cycling women. The spectrum of abnormalities of LH pulses was 8% apulsatile, 27% low frequency/low amplitude, 8% low amplitude/normal frequency, 43% low frequency/normal amplitude, 14% normal frequency/normal amplitude. Of patients studied overnight, 45% demonstrated a pubertal pattern of augmented LH secretion during sleep. Of patients studied repeatedly, 75% demonstrated at least 2 different patterns of LH secretion, and 33% reverted at least once to a normal pattern of secretion. An increase in LH pulse frequency was seen in 12 of 15 subjects in response to naloxone (opioid receptor antagonist). Clonidine (alpha-2 adrenergic agonist) was associated with a decrease in mean LH in 3 of 3 subjects. An increase in LH pulse frequency was seen in 4 of 8 subjects in response to metoclopramide (dopamine receptor antagonist), but the response was not statistically significant. Baseline abnormalities in LH secretion did not appear to influence response to neurotransmitter modulation. 1) HA represents a spectrum of disordered GnRH secretion that can vary over time; 2) LH pulse patterns at baseline do not appear to influence the ability to respond to neurotransmitter modulation; 3) Opioid and adrenergic tone appear to influence the hypothalamic GnRH pulse generator in some individuals with HA.

Influence of postnatal glucocorticoids on hippocampal-dependent learning varies with elevation patterns and administration methods

DTIC Science & Technology

2017-05-22

Influence of postnatal glucocorticoids on hippocampal-dependent learning varies with elevation patterns and administration methods 5b. GRANT NUMBER...of these effects varies with the elevation patterns (level, duration, temporal fluctuation) achieved by different administration methods . In general...learning varies with elevation patterns and administration methods Dragana I. Claflin a, Kevin D. Schmidt a, Zachary D. Vallandingham b, Michal

REPORT TO STATES, REGIONS, AND PROGRAM OFFICES DEMONSTRATING THE USE OF TIME SERIES ANALYSIS TO IDENTIFY NON-POINT SOURCE IMPACTS.

EPA Science Inventory

Land use change, and the implementation of best management practices to remedy the adverse effects of land use change, alter hydrologic patterns, contaminant loading and water quality in freshwater ecosystems. These changes are not constant over time, but vary in response to di...

Variation in Local-Scale Edge Effects: Mechanisms and landscape Context

Treesearch

Therese M. Donovan; Peter W. Jones; Elizabeth M. Annand; Frank R. Thompson III

1997-01-01

Ecological processes near habitat edges often differ from processes away from edges. Yet, the generality of "edge effects" has been hotly debated because results vary tremendously. To understand the factors responsible for this variation, we described nest predation and cowbird distribution patterns in forest edge and forest core habitats on 36 randomly...

An Exercise to Estimate Differential Gene Expression in Human Cells

ERIC Educational Resources Information Center

Chaudhry, M. Ahmad

2006-01-01

The expression of genes in cells of various tissue types varies considerably and is correlated with the function of a particular organ. The pattern of gene expression changes in diseased tissues, in response to therapy or infection and exposure to environmental mutagens, chemicals, ultraviolet light, and ionizing radiation. To better understand…

Differentially expressed proteins of soybean (Glycine max) pulvinus in light and dark conditions

USDA-ARS?s Scientific Manuscript database

Soybean leaves (Glycine max) both track and avoid the sun through turgor changes of the pulvinus tissue at the base of leaves. Pulvinar response is known to be affected by both diurnally varying environmental factors and circadian patterns. Differential expression of the proteins between light and d...

Multivariate pattern analysis of fMRI: the early beginnings.

PubMed

Haxby, James V

2012-08-15

In 2001, we published a paper on the representation of faces and objects in ventral temporal cortex that introduced a new method for fMRI analysis, which subsequently came to be called multivariate pattern analysis (MVPA). MVPA now refers to a diverse set of methods that analyze neural responses as patterns of activity that reflect the varying brain states that a cortical field or system can produce. This paper recounts the circumstances and events that led to the original study and later developments and innovations that have greatly expanded this approach to fMRI data analysis, leading to its widespread application. Copyright © 2012 Elsevier Inc. All rights reserved.

Signal polymorphism under a constant environment: the odd cross in a web decorating spider

NASA Astrophysics Data System (ADS)

Walter, André; Elgar, Mark A.

2016-12-01

The quality of many animal signals varies, perhaps through their use in different contexts or by representing an adaptive response to reduce the risk of exploitation. Spiders of the orb weaver genus Argiope add linear, cruciate or circular silk structures to their orb webs, creating inter- and intra-specific polymorphic visual signals. Different decoration patterns are frequently attributed to different signal effects, but this view is contradicted by commonly observed intraspecific variation in decorating behaviour. Adults of Argiope mascordi are bimodal web decorators, building two distinct patterns, circular and cruciate silk structures. We investigated the variation of patterns under controlled, invariant laboratory conditions. Circular decorations were most frequent, but individuals often switch to the other pattern. This variation neither increased nor decreased over time, suggesting that pattern variability is primarily intrinsic rather than an exclusive response to environmental changes. Accordingly, we discuss the evolutionary implications in the light of the conservation of a single signal function through maintaining the variation of its quality and the alternative view that silk decorations may not represent adaptive signals at all.

Superhydrophobic surfaces using selected zinc oxide microrod growth on ink-jetted patterns.

PubMed

Myint, Myo Tay Zar; Kitsomboonloha, Rungrot; Baruah, Sunandan; Dutta, Joydeep

2011-02-15

The synthesis and properties of superhydrophobic surfaces based on binary surface topography made of zinc oxide (ZnO) microrod-decorated micropatterns are reported. ZnO is intrinsically hydrophilic but can be utilized to create hydrophobic surfaces by creating artificial roughness via microstructuring. Micron scale patterns consisting of nanocrystalline ZnO seed particles were applied to glass substrates with a modified ink-jet printer. Microrods were then grown on the patterns by a hydrothermal process without any further chemical modification. Water contact angle (WCA)(1) up to 153° was achieved. Different micro array patterned surfaces with varying response of static contact angle or sessile droplet analysis are reported. Copyright © 2010 Elsevier Inc. All rights reserved.

Continental-scale variation in controls of summer CO2 in United States lakes

NASA Astrophysics Data System (ADS)

Lapierre, Jean-Francois; Seekell, David A.; Filstrup, Christopher T.; Collins, Sarah M.; Emi Fergus, C.; Soranno, Patricia A.; Cheruvelil, Kendra S.

2017-04-01

Understanding the broad-scale response of lake CO2 dynamics to global change is challenging because the relative importance of different controls of surface water CO2 is not known across broad geographic extents. Using geostatistical analyses of 1080 lakes in the conterminous United States, we found that lake partial pressure of CO2 (pCO2) was controlled by different chemical and biological factors related to inputs and losses of CO2 along climate, topography, geomorphology, and land use gradients. Despite weak spatial patterns in pCO2 across the study extent, there were strong regional patterns in the pCO2 driver-response relationships, i.e., in pCO2 "regulation." Because relationships between lake CO2 and its predictors varied spatially, global models performed poorly in explaining the variability in CO2 for U.S. lakes. The geographically varying driver-response relationships of lake pCO2 reflected major landscape gradients across the study extent and pointed to the importance of regional-scale variation in pCO2 regulation. These results indicate a higher level of organization for these physically disconnected systems than previously thought and suggest that changes in climate and land use could induce shifts in the main pathways that determine the role of lakes as sources and sinks of atmospheric CO2.

Variation in moisture duration as a driver of coexistence by the storage effect in desert annual plants.

PubMed

Holt, Galen; Chesson, Peter

2014-03-01

Temporal environmental variation is a leading hypothesis for the coexistence of desert annual plants. Environmental variation is hypothesized to cause species-specific patterns of variation in germination, which then generates the storage effect coexistence mechanism. However, it has never been shown how sufficient species differences in germination patterns for multispecies coexistence can arise from a shared fluctuating environment. Here we show that nonlinear germination responses to a single fluctuating physical environmental factor can lead to sufficient differences between species in germination pattern for the storage effect to yield coexistence of multiple species. We derive these nonlinear germination responses from experimental data on the effects of varying soil moisture duration. Although these nonlinearities lead to strong species asymmetries in germination patterns, the relative nonlinearity coexistence mechanism is minor compared with the storage effect. However, these asymmetries mean that the storage effect can be negative for some species, which then only persist in the face of interspecific competition through average fitness advantages. This work shows how a low dimensional physical environment can nevertheless stabilize multispecies coexistence when the species have different nonlinear responses to common conditions, as supported by our experimental data. Copyright © 2013 Elsevier Inc. All rights reserved.

Experiential, autonomic, and neural responses during threat anticipation vary as a function of threat intensity and neuroticism.

PubMed

Drabant, Emily M; Kuo, Janice R; Ramel, Wiveka; Blechert, Jens; Edge, Michael D; Cooper, Jeff R; Goldin, Philippe R; Hariri, Ahmad R; Gross, James J

2011-03-01

Anticipatory emotional responses play a crucial role in preparing individuals for impending challenges. They do this by triggering a coordinated set of changes in behavioral, autonomic, and neural response systems. In the present study, we examined the biobehavioral impact of varying levels of anticipatory anxiety, using a shock anticipation task in which unpredictable electric shocks were threatened and delivered to the wrist at variable intervals and intensities (safe, medium, strong). This permitted investigation of a dynamic range of anticipatory anxiety responses. In two studies, 95 and 51 healthy female participants, respectively, underwent this shock anticipation task while providing continuous ratings of anxiety experience and electrodermal responding (Study 1) and during fMRI BOLD neuroimaging (Study 2). Results indicated a step-wise pattern of responding in anxiety experience and electrodermal responses. Several brain regions showed robust responses to shock anticipation relative to safe trials, including the hypothalamus, periaqueductal gray, caudate, precentral gyrus, thalamus, insula, ventrolateral PFC, dorsomedial PFC, and ACC. A subset of these regions demonstrated a linear pattern of increased responding from safe to medium to strong trials, including the bilateral insula, ACC, and inferior frontal gyrus. These responses were modulated by individual differences in neuroticism, such that those high in neuroticism showed exaggerated anxiety experience across the entire task, and reduced brain activation from medium to strong trials in a subset of brain regions. These findings suggest that individual differences in neuroticism may influence sensitivity to anticipatory threat and provide new insights into the mechanism through which neuroticism may confer risk for developing anxiety disorders via dysregulated anticipatory responses. Copyright © 2010 Elsevier Inc. All rights reserved.

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

USGS Publications Warehouse

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

2003-01-01

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

Patterns and profiles of response to incivility in the workplace.

PubMed

Cortina, Lilia M; Magley, Vicki J

2009-07-01

The authors draw on stress and coping theory to understand patterns of individual response to workplace incivility. According to data from 3 employee samples, incivility tended to trigger mildly negative appraisals, which could theoretically differentiate incivility from other categories of antisocial work behavior. Employees experiencing frequent and varied incivility from powerful instigators generally appraised their uncivil encounters more negatively. They responded to this stressor using a multifaceted array of coping strategies, which entailed support seeking, detachment, minimization, prosocial conflict avoidance, and assertive conflict avoidance. These coping reactions depended on the target's appraisal of the situation, the situation's duration, and the organizational position and power of both target and instigator. Implications for organizational science and practice are discussed. (c) 2009 APA, all rights reserved.

Physiological Perturbation Reveals Modularity of Eyespot Development in the Painted Lady Butterfly, Vanessa cardui

PubMed Central

Rhen, Turk; Simmons, Rebecca B.

2016-01-01

Butterfly eyespots are complex morphological traits that can vary in size, shape and color composition even on the same wing surface. Homology among eyespots suggests they share a common developmental basis and function as an integrated unit in response to selection. Despite strong evidence of genetic integration, eyespots can also exhibit modularity or plasticity, indicating an underlying flexibility in pattern development. The extent to which particular eyespots or eyespot color elements exhibit modularity or integration is poorly understood, particularly following exposure to novel conditions. We used perturbation experiments to explore phenotypic correlations among different eyespots and their color elements on the ventral hindwing of V. cardui. Specifically, we identified which eyespots and eyespot features are most sensitive to perturbation by heat shock and injection of heparin—a cold shock mimic. For both treatments, the two central eyespots (3 + 4) were most affected by the experimental perturbations, whereas the outer eyespot border was more resistant to modification than the interior color elements. Overall, the individual color elements displayed a similar response to heat shock across all eyespots, but varied in their response to each other. Graphical modeling also revealed that although eyespots differ morphologically, regulation of eyespot size and colored elements appear to be largely integrated across the wing. Patterns of integration, however, were disrupted following heat shock, revealing that the strength of integration varies across the wing and is strongest between the two central eyespots. These findings support previous observations that document coupling between eyespots 3 + 4 in other nymphalid butterflies. PMID:27560365

Physiological Perturbation Reveals Modularity of Eyespot Development in the Painted Lady Butterfly, Vanessa cardui.

PubMed

Connahs, Heidi; Rhen, Turk; Simmons, Rebecca B

2016-01-01

Butterfly eyespots are complex morphological traits that can vary in size, shape and color composition even on the same wing surface. Homology among eyespots suggests they share a common developmental basis and function as an integrated unit in response to selection. Despite strong evidence of genetic integration, eyespots can also exhibit modularity or plasticity, indicating an underlying flexibility in pattern development. The extent to which particular eyespots or eyespot color elements exhibit modularity or integration is poorly understood, particularly following exposure to novel conditions. We used perturbation experiments to explore phenotypic correlations among different eyespots and their color elements on the ventral hindwing of V. cardui. Specifically, we identified which eyespots and eyespot features are most sensitive to perturbation by heat shock and injection of heparin-a cold shock mimic. For both treatments, the two central eyespots (3 + 4) were most affected by the experimental perturbations, whereas the outer eyespot border was more resistant to modification than the interior color elements. Overall, the individual color elements displayed a similar response to heat shock across all eyespots, but varied in their response to each other. Graphical modeling also revealed that although eyespots differ morphologically, regulation of eyespot size and colored elements appear to be largely integrated across the wing. Patterns of integration, however, were disrupted following heat shock, revealing that the strength of integration varies across the wing and is strongest between the two central eyespots. These findings support previous observations that document coupling between eyespots 3 + 4 in other nymphalid butterflies.

Cortical Activation in Response to Pure Taste Stimuli During the Physiological States of Hunger and Satiety

PubMed Central

Haase, Lori; Cerf-Ducastel, Barbara; Murphy, Claire

2009-01-01

This event-related functional magnetic resonance imaging (er-fMRI) study investigated BOLD signal change in response to a series of pure gustatory stimuli that varied in stimulus quality when subjects were hungry and sated with a nutritional preload. Group analyses showed significant differences in activation in the hunger minus satiety condition in response to sucrose, caffeine, saccharin, and citric acid within the thalamus, hippocampus, and parahippocampus. When examining the hunger and satiety conditions, activation varied as a function of stimulus, with the majority of the stimuli exhibiting significantly greater activation in the hunger state within the insula, thalamus, and substantia nigra, in contrast to decreased activation in the satiated state within the parahippocampus, hippocampus, amygdala, and anterior cingulate. Region of interest (ROI) analysis revealed two significant interactions, ROI by physiology and ROI by physiology by stimulus. In the satiety condition, the primary (inferior and superior insulae) and secondary (OFC 11 and OFC 47) taste regions exhibited significantly greater brain activation in response to all stimuli than regions involved in processing eating behavior (hypothalamus), affect (amygdala), and memory (hippocampus, parahippocampus and entorhinal cortex). These same regions demonstrated significantly greater activation within the hunger condition than the satiety condition, with the exception of the superior insula. Furthermore, the patterns of activation differed as a function taste stimulus, with greater activation in response to sucrose than to the other stimuli. These differential patterns of activation suggest that the physiological states of hunger and satiety produce divergent activation in multiple brain areas in response to different pure gustatory stimuli. PMID:19007893

Cortical activation in response to pure taste stimuli during the physiological states of hunger and satiety.

PubMed

Haase, Lori; Cerf-Ducastel, Barbara; Murphy, Claire

2009-02-01

This event-related functional magnetic resonance imaging (er-fMRI) study investigated BOLD signal change in response to a series of pure gustatory stimuli that varied in stimulus quality when subjects were hungry and sated with a nutritional pre-load. Group analyses showed significant differences in activation in the hunger minus satiety condition in response to sucrose, caffeine, saccharin, and citric acid within the thalamus, hippocampus, and parahippocampus. When examining the hunger and satiety conditions, activation varied as a function of stimulus, with the majority of the stimuli exhibiting significantly greater activation in the hunger state within the insula, thalamus, and substantia nigra, in contrast to decreased activation in the satiated state within the parahippocampus, hippocampus, amygdala, and anterior cingulate. Region of interest (ROI) analysis revealed two significant interactions, ROI by physiology and ROI by physiology by stimulus. In the satiety condition, the primary (inferior and superior insulae) and secondary (OFC 11 and OFC 47) taste regions exhibited significantly greater brain activation in response to all stimuli than regions involved in processing eating behavior (hypothalamus), affect (amygdala), and memory (hippocampus, parahippocampus and entorhinal cortex). These same regions demonstrated significantly greater activation within the hunger condition than the satiety condition, with the exception of the superior insula. Furthermore, the patterns of activation differed as a function taste stimulus, with greater activation in response to sucrose than to the other stimuli. These differential patterns of activation suggest that the physiological states of hunger and satiety produce divergent activation in multiple brain areas in response to different pure gustatory stimuli.

Examining Communicative Behaviors in a 3-Year-Old Boy Who Is Blind.

ERIC Educational Resources Information Center

Perfect, Michelle M.

2001-01-01

The communication patterns of a 3-year-old boy who is blind were observed during 35 videotaped classroom sessions to determine if his echolalic responses varied according to school activity and message category. Analysis revealed that, although the child was expressive with adults, he had difficulty communicating with his peers and in producing…

Can local adaptation explain varying patterns of herbivory tolerance in a recently introduced woody plant in North America?

USDA-ARS?s Scientific Manuscript database

Trends in tree mortality have been linked to global scale environmental changes, such as extreme drought and heat stress, more frequent and intense fires, and increased episodic outbreaks of insects and pathogens. Finer scale studies have also focused on survival and mortality in response to physiol...

Response of ectomycorrhizal fungus sporocarp production to varying levels and patterns of green-tree retention.

Treesearch

Daniel L. Luoma; Joyce L. Eberhart; Randy Molina; Michael P. Amaranthus

2004-01-01

Forest management activities can reduce ectomycorrhizal fungus diversity and forest regeneration success. We examine contrasts in structural retention as they affect sporocarp production of ectomycorrhizal fungi (EMF)--functional guild of organisms well suited as indicators of disturbance effects on below-ground ecosystems. Our results are from an experiment that tests...

Accurate step-hold tracking of smoothly varying periodic and aperiodic probability.

PubMed

Ricci, Matthew; Gallistel, Randy

2017-07-01

Subjects observing many samples from a Bernoulli distribution are able to perceive an estimate of the generating parameter. A question of fundamental importance is how the current percept-what we think the probability now is-depends on the sequence of observed samples. Answers to this question are strongly constrained by the manner in which the current percept changes in response to changes in the hidden parameter. Subjects do not update their percept trial-by-trial when the hidden probability undergoes unpredictable and unsignaled step changes; instead, they update it only intermittently in a step-hold pattern. It could be that the step-hold pattern is not essential to the perception of probability and is only an artifact of step changes in the hidden parameter. However, we now report that the step-hold pattern obtains even when the parameter varies slowly and smoothly. It obtains even when the smooth variation is periodic (sinusoidal) and perceived as such. We elaborate on a previously published theory that accounts for: (i) the quantitative properties of the step-hold update pattern; (ii) subjects' quick and accurate reporting of changes; (iii) subjects' second thoughts about previously reported changes; (iv) subjects' detection of higher-order structure in patterns of change. We also call attention to the challenges these results pose for trial-by-trial updating theories.

Metastability and emergent performance of dynamic interceptive actions.

PubMed

Pinder, Ross A; Davids, Keith; Renshaw, Ian

2012-09-01

Adaptive patterning of human movement is context specific and dependent on interacting constraints of the performer-environment relationship. Flexibility of skilled behaviour is predicated on the capacity of performers to move between different states of movement organisation to satisfy dynamic task constraints, previously demonstrated in studies of visual perception, bimanual coordination, and an interceptive combat task. Metastability is a movement system property that helps performers to remain in a state of relative coordination with their performance environments, poised between multiple co-existing states (stable and distinct movement patterns or responses). The aim of this study was to examine whether metastability could be exploited in externally paced interceptive actions in fast ball sports, such as cricket. Here we report data on metastability in performance of multi-articular hitting actions by skilled junior cricket batters (n=5). Participants' batting actions (key movement timings and performance outcomes) were analysed in four distinct performance regions varied by ball pitching (bounce) location. Results demonstrated that, at a pre-determined distance to the ball, participants were forced into a meta-stable region of performance where rich and varied patterns of functional movement behaviours emerged. Participants adapted the organisation of responses, resulting in higher levels of variability in movement timing in this performance region, without detrimental effects on the quality of interceptive performance outcomes. Findings provide evidence for the emergence of metastability in a dynamic interceptive action in cricket batting. Flexibility and diversity of movement responses were optimised using experiential knowledge and careful manipulation of key task constraints of the specific sport context. Copyright © 2012 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Effect of genotype and environment on branching in weedy green millet (Setaria viridis) and domesticated foxtail millet (Setaria italica) (Poaceae).

PubMed

Doust, Andrew N; Kellogg, Elizabeth A

2006-04-01

Many domesticated crops are derived from species whose life history includes weedy characteristics, such as the ability to vary branching patterns in response to environmental conditions. However, domesticated crop plants are characterized by less variable plant architecture, as well as by a general reduction in vegetative branching compared to their progenitor species. Here we examine weedy green millet and its domesticate foxtail millet that differ in the number of tillers (basal branches) and axillary branches along each tiller. Branch number in F(2:3) progeny of a cross between the two species varies with genotype, planting density, and other environmental variables, with significant genotype-environment interactions (GEI). This is shown by a complex pattern of reaction norms and by variation in the pattern of significant quantitative trait loci (QTL) amongst trials. Individual and joint analyses of high and low density trials indicate that most QTL have significant GEI. Dominance and epistasis also explain some variation in branching. Likely candidate genes underlying the QTL (based on map position and phenotypic effect) include teosinte branched1 and barren stalk1. Phytochrome B, which has been found to affect response to shading in other plants, explains little or no variation. Much variation in branching is explained by QTL that do not have obvious candidate genes from maize or rice.

Families discovering asthma in their high-risk infants and toddlers with severe persistent disease.

PubMed

Koenig, Karel

2006-02-01

Interpretive phenomenology was used to discover the earliest experiences of families of children younger than 4 years hospitalized for severe persistent asthma. The children who were African American or Latino and living in poverty were at highest risk of morbidity and mortality. Three families with distinctly varied responses to early symptoms were chosen from an investigation of 11 families for this study. Each gave three home interviews and participated in home observations. All families experienced life-changing responses to their children's distressed breathing. All had experienced asthma in themselves or others that shaped their beliefs and management patterns. Family experiences prior to and following diagnosis are discussed. Findings suggest that understanding these experiences and respecting families' earliest responses will help clarify established family management patterns for severe asthma in infants and toddlers and will enhance the ability of providers to guide the care of these families and children.

Visual Attention Patterns of Women with Androphilic and Gynephilic Sexual Attractions.

PubMed

Dawson, Samantha J; Fretz, Katherine M; Chivers, Meredith L

2017-01-01

Women who report exclusive sexual attractions to men (i.e., androphilia) exhibit gender-nonspecific patterns of sexual response-similar magnitude of genital response to both male and female targets. Interestingly, women reporting any degree of attraction to women (i.e., gynephilia) show significantly greater sexual responses to stimuli depicting female targets compared to male targets. At present, the mechanism(s) underlying these patterns are unknown. According to the information processing model (IPM), attentional processing of sexual cues initiates sexual responding; thus, attention to sexual cues may be one mechanism to explain the observed within-gender differences in specificity findings among women. The purpose of the present study was to examine patterns of initial and controlled visual attention among women with varying sexual attractions. We used eye tracking to assess visual attention to sexually preferred and nonpreferred cues in a sample of 164 women who differed in their degree of androphilia and gynephilia. We found that both exclusively and predominantly androphilic women showed gender-nonspecific patterns of initial attention. In contrast, ambiphilic (i.e., concurrent androphilia and gynephilia) and predominantly/exclusively gynephilic women oriented more quickly toward female targets. Controlled attention patterns mirrored patterns of self-reported sexual attractions for three of these four groups of women, such that gender-specific patterns of visual attention were found for androphilic and gynephilic women. Ambiphilic women looked significantly longer at female targets compared to male targets. These findings support predictions from the IPM and suggest that both initial and controlled attention to sexual cues may be mechanisms contributing to within-gender variation in sexual responding.

Sources of variation in plasma corticosterone and dehydroepiandrosterone in the male northern cardinal (Cardinalis cardinalis): II. Effects of urbanization, food supplementation and social stress.

PubMed

Wright, Sarah; Fokidis, H Bobby

2016-09-01

Perturbations in an organism's environment can induce significant shifts in hormone secretory patterns. In this context, the glucocorticoid (GC) steroids secreted by the adrenal cortex have received much attention from ecologists and behaviorists due to their role in the vertebrate stress response. Adrenal GCs, such as corticosterone (CORT), are highly responsive to instability in environmental and social conditions. However, little is understood about how adrenal dehydroepiandrosterone (DHEA) is influenced by changing conditions. We conducted field experiments to determine how circulating CORT and DHEA vary during restraint stress in the male northern cardinals (Cardinalis cardinalis). Specifically, we examined how four different changes in the physical (urbanization and food availability) and social (territorial conflict, distress of a mate) environment affect CORT and DHEA levels. The majority of cardinals responded to restraint stress by increasing and decreasing CORT and DHEA, respectively, however this depended on sampling context. Cardinals sampled from urban habitats had both lower initial and restraint stress CORT concentrations, but a comparable DHEA pattern to those sampled from a forest. Supplementing food to territorial males did not alter circulating initial DHEA or CORT concentrations nor did it change the response to restraint stress when compared to unsupplemented controls. Exposing cardinals to varying durations of song playback, which mimics a territorial intrusion, did not affect CORT levels, but did attenuate the DHEA response to restraint stress. Examining a larger dataset of males captured before, after or at the same time as their female mate, allowed us to address how the stress of a captured mate affected the male's CORT and DHEA response. Males showed elevated initial and restraint CORT and DHEA when their female mate was captured first. Taken together, these data demonstrate that both CORT and DHEA secretion patterns depends on environmental, and particularly current social conditions. Copyright © 2016 Elsevier Inc. All rights reserved.

Children's responses to low parental mood. II: Associations with family perceptions of parenting styles and child distress.

PubMed

Solantaus-Simula, Tytti; Punamäki, Raija-Leena; Beardslee, William R

2002-03-01

In an earlier article (part 1) the authors identified four patterns of children's responses to parental low mood: Active Empathy, Emotional Overinvolvement, Indifference, and Avoidance. They then hypothesized that these response patterns were related to parenting styles and to discrepancies in family members' perceptions of parenting and child mental distress. A normal population sample of 990 twelve-year-old Finnish children and their mothers (843) and fathers (573) was used. Within-family multivariate analyses conducted in mother-father-child triads (470) were used to examine whether quality of parenting varied according to children's responses and whether parents' and children's perceptions of parenting and child distress were different. Children in the Active Empathy and Indifference groups experienced more positive parenting than those in the other two groups. Discrepancies in family members' perceptions of child distress and mothering and fathering were especially characteristic of the Emotional Overinvolvement group. Typical for the Avoidance group was a within-family agreement on poor parenting and severe child distress. Children's response patterns as regards parental low mood are related to family dynamics. The study suggests that discrepancies in parents' and children's perceptions of parenting and child distress can be meaningful in understanding family interactions and child development and well-being.

The pathway to intelligent implants: osteoblast response to nano silicon-doped hydroxyapatite patterning

PubMed Central

Munir, G.; Koller, G.; Di Silvio, L.; Edirisinghe, M. J.; Bonfield, W.; Huang, J.

2011-01-01

Bioactive hydroxyapatite (HA) with addition of silicon (Si) in the crystal structure (silicon-doped hydroxyapatite (SiHA)) has become a highly attractive alternative to conventional HA in bone replacement owing to the significant improvement in the in vivo bioactivity and osteoconductivity. Nanometre-scaled SiHA (nanoSiHA), which closely resembles the size of bone mineral, has been synthesized in this study. Thus, the silicon addition provides an extra chemical cue to stimulate and enhance bone formation for new generation coatings, and the next stage in metallic implantation design is to further improve cellular adhesion and proliferation by control of cell alignment. Topography has been found to provide a powerful set of signals for cells and form contact guidance. Using the recently developed novel technique of template-assisted electrohydrodynamic atomization (TAEA), patterns of pillars and tracks of various dimensions of nanoSiHA were achieved. Modifying the parameters of TAEA, the resolution of pattern structures was controlled, enabling the topography of a substrate to be modified accordingly. Spray time, flow rate and distance between the needle and substrate were varied to improve the pattern formation of pillars and tracks. The 15 min deposition time provided the most consistent patterned topography with a distance of 50 mm and flow rate of 4 µl min−1. A titanium substrate was patterned with pillars and tracks of varying widths, line lengths and distances under the optimized TAEA processing condition. A fast bone-like apatite formation rate was found on nanoSiHA after immersion in simulated body fluid, thus demonstrating its high in vitro bioactivity. Primary human osteoblast (HOB) cells responded to SiHA patterns by stretching of the filopodia between track and pillar, attaching to the apex of the pillar pattern and stretching between two. HOB cells responded to the track pattern by elongating along and between the track, and the length of HOB cells was proportional to the gaps between track patterns, but this relationship was not observed on the pillar patterns. The study has therefore provided an insight for future design of next generation implant surfaces to control and guide cellular responses, while TAEA patterning provides a controllable technique to provide topography to medical implants. PMID:21208969

Effects of prevailing winds on turbidity of a shallow estuary.

PubMed

Cho, Hyun Jung

2007-06-01

Estuarine waters are generally more turbid than lakes or marine waters due to greater algal mass and continual re-suspension of sediments. The varying effects of diurnal and seasonal prevailing winds on the turbidity condition of a wind-dominated estuary were investigated by spatial and statistical analyses of wind direction, water level, turbidity, chlorophyll a, and PAR (Photosynthetically Active Radiation) collected in Lake Pontchartrain, Louisiana, USA. The prolonged prevailing winds were responsible for the long-term, large-scale turbidity pattern of the estuary, whereas the short-term changes in wind direction had differential effects on turbidity and water level in varying locations. There were temporal and spatial changes in the relationship between vertical light attenuation coefficient (Kd) and turbidity, which indicate difference in phytoplankton and color also affect Kd. This study demonstrates that the effect of wind on turbidity and water level on different shores can be identified through system-specific analyses of turbidity patterns.

Effects of Prevailing Winds on Turbidity of a Shallow Estuary

PubMed Central

Cho, Hyun Jung

2007-01-01

Estuarine waters are generally more turbid than lakes or marine waters due to greater algal mass and continual re-suspension of sediments. The varying effects of diurnal and seasonal prevailing winds on the turbidity condition of a wind-dominated estuary were investigated by spatial and statistical analyses of wind direction, water level, turbidity, chlorophyll a, and PAR (Photosynthetically Active Radiation) collected in Lake Pontchartrain, Louisiana, USA. The prolonged prevailing winds were responsible for the long-term, large-scale turbidity pattern of the estuary, whereas the short-term changes in wind direction had differential effects on turbidity and water level in varying locations. There were temporal and spatial changes in the relationship between vertical light attenuation coefficient (Kd) and turbidity, which indicate difference in phytoplankton and color also affect Kd. This study demonstrates that the effect of wind on turbidity and water level on different shores can be identified through system-specific analyses of turbidity patterns. PMID:17617683

The potential for adaptive evolution of pollen grain size in Mimulus guttatus.

PubMed

Lamborn, Ellen; Cresswell, James E; Macnair, Mark R

2005-07-01

We tested whether pollen grain size (PGS) shows heritable variation in three independent populations of Mimulus guttatus by imposing artificial selection for this character. In addition, we looked for correlated responses to selection in a range of 15 other floral characters. Heritable variation in PGS was found in all three populations, with heritabilities of between 19 and 40% (average 30%). After three generations, upward and downward lines differed on average by 30% in pollen volume. No consistent patterns of correlated response were found in other characters, indicating that PGS can respond to selective forces acting on PGS alone. Possible selection mechanisms on PGS in this species could include intermale selection, if large pollen grains produce more competitive gametophytes; or optimization of patterns of resource allocation, if local mate competition varies.

Time Domains of the Hypoxic Ventilatory Response and Their Molecular Basis

PubMed Central

Pamenter, Matthew E.; Powell, Frank L.

2016-01-01

Ventilatory responses to hypoxia vary widely depending on the pattern and length of hypoxic exposure. Acute, prolonged, or intermittent hypoxic episodes can increase or decrease breathing for seconds to years, both during the hypoxic stimulus, and also after its removal. These myriad effects are the result of a complicated web of molecular interactions that underlie plasticity in the respiratory control reflex circuits and ultimately control the physiology of breathing in hypoxia. Since the time domains of the physiological hypoxic ventilatory response (HVR) were identified, considerable research effort has gone toward elucidating the underlying molecular mechanisms that mediate these varied responses. This research has begun to describe complicated and plastic interactions in the relay circuits between the peripheral chemoreceptors and the ventilatory control circuits within the central nervous system. Intriguingly, many of these molecular pathways seem to share key components between the different time domains, suggesting that varied physiological HVRs are the result of specific modifications to overlapping pathways. This review highlights what has been discovered regarding the cell and molecular level control of the time domains of the HVR, and highlights key areas where further research is required. Understanding the molecular control of ventilation in hypoxia has important implications for basic physiology and is emerging as an important component of several clinical fields. PMID:27347896

Mapping Forest Structure From Tree Clump And Opening Patterns Across Landscapes With Airborne Lidar To Study Response To Disturbances And Map Habitat

NASA Astrophysics Data System (ADS)

Kane, V. R.; McGaughey, R. J.; Asner, G. P.; Kane, J. T.; Churchill, D.; Vaughn, N.

2016-12-01

Most natural forests are structured as mosaics of tree clumps and openings. These mosaics reflect both the underlying patterns of the biophysical environment and the finer scale patterns of disturbance and regrowth. We have developed methods to quantify and map patterns of tree clumps and openings at scales from within stands to landscapes using airborne LiDAR. While many studies have used LiDAR data to identify individual trees, we also identify clumps as adjacent trees with similar heights within a stand that likely established at a similar time following a disturbance. We characterize openings by both size class and shape complexity. Spatial statistics are used to identify patterns of tree clumps and openings at the local (0.81 ha) scale, and these patterns are then mapped across entire landscapes. We use LiDAR data acquired over Sequoia National Park, California, USA, to show how forest structure varies with patterns of productivity driven by the biophysical environment. We then show how clump and opening patterns vary with different fire histories and how recent drought mortality correlates with different tree clump and opening structural mosaics. We also demonstrate that nesting sites for the California spotted owl, a species of concern, are associated with clumps of large (>32 and especially >48 m) trees but that the surrounding foraging areas consist of a heterogeneous pattern of forest structure. These methods are especially useful for studying clumps of large trees, which dominate above ground forest biomass, and the effects of disturbance on the abundance and pattern of large trees as key forest structures.

Gender-specificity of solitary and dyadic sexual desire among gynephilic and androphilic women and men.

PubMed

Dawson, Samantha J; Chivers, Meredith L

2014-04-01

Incentive motivation theory proposes that sexual desire emerges from sexual arousal, and is triggered by sexually competent stimuli. Research demonstrates gender and sexual orientation differences in the features that contribute to the competency of sexual stimuli. Men's and gynephilic women's genital arousal tends to be gender-specific with preferred gender eliciting significantly greater genital arousal than nonpreferred gender. In contrast, stimuli depicting preferred and nonpreferred gender elicit similar degrees of genital arousal among androphilic women, termed a gender-nonspecific pattern. Given these differences in the features that elicit a sexual response, and that sexual desire is proposed to emerge from sexual arousal, the question remains as to whether sexual desire would emerge only through exposure to preferred stimuli or whether patterns of responsive desire would parallel those observed for genital arousal. The study aims to examine patterns of dyadic and solitary sexual desire in response to stimuli differing in incentive value. Thirty androphilic women, 21 gynephilic women, 21 gynephilic men, and 16 androphilic men participated in a sexual psychophysiological session. Participants viewed sexual stimuli that varied the gender of the actors and the intensity of sexual activities depicted. Participants reported their degree of desire for sex with a partner (dyadic desire) and desire to masturbate (solitary desire), before and after each film. Men and gynephilic women exhibited gender-specific patterns of sexual desire. Androphilic women's dyadic desire showed significantly less differentiation between genders, and their solitary desire did not differentiate at all. No gender difference was observed for either type of desire. All groups reported greater desire as stimulus intensity increased. Gender-nonspecific sexual response is not limited to the sexual arousal patterns of androphilic women, but extends to include responsive sexual desire. Men and gynephilic women, however, show gender-specific responsive sexual desire that parallels their sexual arousal patterns. © 2014 International Society for Sexual Medicine.

Sepsis-induced myocardial dysfunction and myocardial protection from ischemia/reperfusion injury.

PubMed

McDonough, Kathleen H; Virag, Jitka Ismail

2006-01-01

Sepsis, bacteremia and inflammation cause myocardial depression. The mechanism of the dysfunction is not clearly established partly because dysfunction can be elicited by many different mechanisms which can all manifest in disruption of myocardial mechanical function. In addition the models of sepsis and bacteremia and inflammation may vary drastically in the sequence of the coordinated immune response to the inflammatory or septic stimulus. Patterns of cytokine expression can vary as can other responses of the immune system. Patterns of neurohumoral activation in response to the stress of sepsis or bacteremia or inflammation can also vary in both magnitude of response and temporal sequence of response. Stress induced activation of the sympathetic nervous system and humoral responses to stress have a wide range of intensity that can be elicited. The fairly uniform response of the myocardium indicating cardiac dysfunction is surprisingly constant. Systolic performance, as measured by stroke volume or cardiac output and pressure work as estimated by ventricular pressure, are impaired when myocardial contraction is compromised. At times, diastolic function, assessed by ventricular relaxation and filling, is impaired. In addition to the dysfunction that occurs, there is a longer term response of the myocardium to sepsis, and this response is similar to that which is elicited in the heart by multiple brief ischemia/reperfusion episodes and by numerous pharmacological agents as well as heat stress and modified forms of lipopolysaccharide. The myocardium develops protection after an initial stress such that during a second stress, the myocardium does not exhibit as much damage as does a non-protected heart. Many agents can induce this protection which has been termed preconditioning. Both early preconditioning (protection that is measurable min to hours after the initial stimulus) and late preconditioning (protection that is measurable hours to days after the initial trigger or stimulus) are effective in protecting the heart from prolonged ischemia and reperfusion injury. Understanding the mechanisms of sepsis/bacteremia induced dysfunction and protection and if the dysfunction and protection are the products of the same intracellular pathways is important in protecting the heart from failing to perform adequately during severe sepsis and/or septic shock and for understanding the multitude of mechanism by which the myocardium maintains reserve capacity.

Masked priming effect reflects evidence accumulated by the prime.

PubMed

Kinoshita, Sachiko; Norris, Dennis

2010-01-01

In the same-different match task, masked priming is observed with the same responses but not different responses. Norris and Kinoshita's (2008) Bayesian reader account of masked priming explains this pattern based on the same principle as that explaining the absence of priming for nonwords in the lexical decision task. The pattern of priming follows from the way the model makes optimal decisions in the two tasks; priming does not depend on first activating the prime and then the target. An alternative explanation is in terms of a bias towards responding "same" that exactly counters the facilitatory effect of lexical access. The present study tested these two views by varying both the degree to which the prime predicts the response and the visibility of the prime. Unmasked primes produced effects expected from the view that priming is influenced by the degree to which the prime predicts the response. In contrast, with masked primes, the size of priming for the same response was completely unaffected by predictability. These results rule out response bias as an explanation of the absence of masked priming for different responses and, in turn, indicate that masked priming is not a consequence of automatic lexical access of the prime.

The development of automaticity in short-term memory search: Item-response learning and category learning.

PubMed

Cao, Rui; Nosofsky, Robert M; Shiffrin, Richard M

2017-05-01

In short-term-memory (STM)-search tasks, observers judge whether a test probe was present in a short list of study items. Here we investigated the long-term learning mechanisms that lead to the highly efficient STM-search performance observed under conditions of consistent-mapping (CM) training, in which targets and foils never switch roles across trials. In item-response learning, subjects learn long-term mappings between individual items and target versus foil responses. In category learning, subjects learn high-level codes corresponding to separate sets of items and learn to attach old versus new responses to these category codes. To distinguish between these 2 forms of learning, we tested subjects in categorized varied mapping (CV) conditions: There were 2 distinct categories of items, but the assignment of categories to target versus foil responses varied across trials. In cases involving arbitrary categories, CV performance closely resembled standard varied-mapping performance without categories and departed dramatically from CM performance, supporting the item-response-learning hypothesis. In cases involving prelearned categories, CV performance resembled CM performance, as long as there was sufficient practice or steps taken to reduce trial-to-trial category-switching costs. This pattern of results supports the category-coding hypothesis for sufficiently well-learned categories. Thus, item-response learning occurs rapidly and is used early in CM training; category learning is much slower but is eventually adopted and is used to increase the efficiency of search beyond that available from item-response learning. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Spatial structure in the diet of imperial eagles Aquila heliaca in Kazakhstan

USGS Publications Warehouse

Katzner, T.E.; Bragin, E.A.; Knick, S.T.; Smith, A.T.

2006-01-01

We evaluated the relationship between spatial variability in prey and food habits of eastern imperial eagles Aquila heliaca at a 90,000 ha national nature reserve in north-central Kazakhstan. Eagle diet varied greatly within the population and the spatial structure of eagle diet within the population varied according to the scale of measurement. Patterns in dietary response were inconsistent with expectations if either ontogenetic imprinting or competition determined diet choice, but they met expectations if functional response determined diet. Eagles nesting near a high-density prey resource used that resource almost exclusively. In contrast, in locations with no single high-density prey species, eagles' diet was more diverse. Our results demonstrate that spatial structuring of diet of vertebrate predators can provide important insight into the mechanisms that drive dietary decisions. ?? OIKOS.

Combinations of response-reinforcer relations in periodic and aperiodic schedules.

PubMed

Kuroda, Toshikazu; Cançado, Carlos R X; Lattal, Kennon A; Elcoro, Mirari; Dickson, Chata A; Cook, James E

2013-03-01

Key pecking of 4 pigeons was studied under a two-component multiple schedule in which food deliveries were arranged according to a fixed and a variable interfood interval. The percentage of response-dependent food in each component was varied, first in ascending (0, 10, 30, 70 and 100%) and then in descending orders, in successive conditions. The change in response rates was positively related to the percentage of response-dependent food in each schedule component. Across conditions, positively accelerated and linear patterns of responding occurred consistently in the fixed and variable components, respectively. These results suggest that the response-food dependency determines response rates in periodic and aperiodic schedules, and that the temporal distribution of food determines response patterns independently of the response-food dependency. Running rates, but not postfood pauses, also were positively related to the percentage of dependent food in each condition, in both fixed and variable components. Thus, the relation between overall response rate and the percentage of dependent food was mediated by responding that occurred after postfood pausing. The findings together extend previous studies wherein the dependency was either always present or absent, and increase the generality of the effects of variations in the response-food dependency from aperiodic to periodic schedules. © Society for the Experimental Analysis of Behavior.

Task 1, Fractal characteristics of drainage patterns observed in the Appalachian Valley and Ridge and Plateau provinces

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

Wilson, T.; Dominic, J.; Halverson, J.

1996-04-10

Drainage patterns observed in the Appalachian Valley and Ridge and Plateau provinces exhibit distinctly different patterns. The patterns appear to be controlled by varying influences of local structural and lithologic variability. Drainage patterns in the Valley and Ridge study area can be classified as a combination of dendritic and trellis arrangements. The patterns vary over short distances in both the strike and dip directions. In the Granny Creek area of the Appalachian Plateau drainage patterns are predominantly dendritic. The possibility that these drainage patterns have fractal characteristics was evaluated by box-counting. Results obtained from box counting do not yield amore » well defined fractal regime in either areas. In the Valley and Ridge a space-filling, or random regime (D=2) is observed for boxes with side-lengths of 300 meters and greater. Below 300 meters, large changes in D occur between consecutively smaller box sizes. From side lengths of 300 to 150m, 150 to 75m, and 75 to 38m, D is measured at 1.77, 1.39, and 1.08 respectively. For box sizes less than 38m the fractal dimension is 1 or less. While the l0g-log response of the box counting data is nonlinear and does not define a fractal regime, the curves offer the possibility of characterizing non-fractal patterns. The rate at which D drops outside the random regime correlates to drainage density. D in areas with a smaller density of drainage segments fell toward saturation (D=1) more abruptly. The break-away point from the random regime and the transition to the saturated regime may provide useful information about the relative lengths of stream segments.« less

Calcium Dynamics in Basal Dendrites of Layer 5A and 5B Pyramidal Neurons Is Tuned to the Cell-Type Specific Physiological Action Potential Discharge

PubMed Central

Krieger, Patrik; de Kock, Christiaan P. J.; Frick, Andreas

2017-01-01

Layer 5 (L5) is a major neocortical output layer containing L5A slender-tufted (L5A-st) and L5B thick-tufted (L5B-tt) pyramidal neurons. These neuron types differ in their in vivo firing patterns, connectivity and dendritic morphology amongst other features, reflecting their specific functional role within the neocortical circuits. Here, we asked whether the active properties of the basal dendrites that receive the great majority of synaptic inputs within L5 differ between these two pyramidal neuron classes. To quantify their active properties, we measured the efficacy with which action potential (AP) firing patterns backpropagate along the basal dendrites by measuring the accompanying calcium transients using two-photon laser scanning microscopy in rat somatosensory cortex slices. For these measurements we used both “artificial” three-AP patterns and more complex physiological AP patterns that were previously recorded in anesthetized rats in L5A-st and L5B-tt neurons in response to whisker stimulation. We show that AP patterns with relatively few APs (3APs) evoke a calcium response in L5B-tt, but not L5A-st, that is dependent on the temporal pattern of the three APs. With more complex in vivo recorded AP patterns, the average calcium response was similar in the proximal dendrites but with a decay along dendrites (measured up to 100 μm) of L5B-tt but not L5A-st neurons. Interestingly however, the whisker evoked AP patterns—although very different for the two cell types—evoke similar calcium responses. In conclusion, although the effectiveness with which different AP patterns evoke calcium transients vary between L5A-st and L5B-tt cell, the calcium influx appears to be tuned such that whisker-evoked calcium transients are within the same dynamic range for both cell types. PMID:28744201

Image projection optical system for measuring pattern electroretinograms

NASA Astrophysics Data System (ADS)

Starkey, Douglas E.; Taboada, John; Peters, Daniel

1994-06-01

The use of the pattern-electroretinogram (PERG) as a noninvasive diagnostic tool for the early detection of glaucoma has been supported by a number of recent studies. We have developed a unique device which uses a laser interferometer to generate a sinusoidal fringe pattern that is presented to the eye in Maxwellian view for the purpose of producing a PERG response. The projection system stimulates a large visual field and is designed to bypass the optics of the eye in order to measure the true retinal response to a temporally alternating fringe pattern. The contrast, spatial frequency, total power output, orientation, alternating temporal frequency, and field location of the fringe pattern presented to the eye can all be varied by the device. It is critical for these parameters to be variable so that optimal settings may be determined for the normal state and any deviation from it, i.e. early or preclinical glaucoma. Several interferometer designs and optical projection systems were studied in order to design a compact system which provided the desired variable pattern stimulus to the eye. This paper will present a description of the clinical research instrument and its performance with the primary emphasis on the optical system design as it relates to the fringe pattern generation and other optical parameters. Examples of its use in the study of glaucoma diagnosis will also be presented.

Impact of decadal cloud variations on the Earth’s energy budget

DOE PAGES

Zhou, Chen; Zelinka, Mark D.; Klein, Stephen A.

2016-10-31

Feedbacks of clouds on climate change strongly influence the magnitude of global warming. Cloud feedbacks, in turn, depend on the spatial patterns of surface warming, which vary on decadal timescales. Therefore, the magnitude of the decadal cloud feedback could deviate from the long-term cloud feedback. We present climate model simulations to show that the global mean cloud feedback in response to decadal temperature fluctuations varies dramatically due to time variations in the spatial pattern of sea surface temperature. Here, we find that cloud anomalies associated with these patterns significantly modify the Earth’s energy budget. Specifically, the decadal cloud feedback betweenmore » the 1980s and 2000s is substantially more negative than the long-term cloud feedback. This is a result of cooling in tropical regions where air descends, relative to warming in tropical ascent regions, which strengthens low-level atmospheric stability. Under these conditions, low-level cloud cover and its reflection of solar radiation increase, despite an increase in global mean surface temperature. Our results suggest that sea surface temperature pattern-induced low cloud anomalies could have contributed to the period of reduced warming between 1998 and 2013, and o er a physical explanation of why climate sensitivities estimated from recently observed trends are probably biased low.« less

Impact of decadal cloud variations on the Earth’s energy budget

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

Zhou, Chen; Zelinka, Mark D.; Klein, Stephen A.

Feedbacks of clouds on climate change strongly influence the magnitude of global warming. Cloud feedbacks, in turn, depend on the spatial patterns of surface warming, which vary on decadal timescales. Therefore, the magnitude of the decadal cloud feedback could deviate from the long-term cloud feedback. We present climate model simulations to show that the global mean cloud feedback in response to decadal temperature fluctuations varies dramatically due to time variations in the spatial pattern of sea surface temperature. Here, we find that cloud anomalies associated with these patterns significantly modify the Earth’s energy budget. Specifically, the decadal cloud feedback betweenmore » the 1980s and 2000s is substantially more negative than the long-term cloud feedback. This is a result of cooling in tropical regions where air descends, relative to warming in tropical ascent regions, which strengthens low-level atmospheric stability. Under these conditions, low-level cloud cover and its reflection of solar radiation increase, despite an increase in global mean surface temperature. Our results suggest that sea surface temperature pattern-induced low cloud anomalies could have contributed to the period of reduced warming between 1998 and 2013, and o er a physical explanation of why climate sensitivities estimated from recently observed trends are probably biased low.« less

Impact of decadal cloud variations on the Earth's energy budget

NASA Astrophysics Data System (ADS)

Zhou, Chen; Zelinka, Mark D.; Klein, Stephen A.

2016-12-01

Feedbacks of clouds on climate change strongly influence the magnitude of global warming. Cloud feedbacks, in turn, depend on the spatial patterns of surface warming, which vary on decadal timescales. Therefore, the magnitude of the decadal cloud feedback could deviate from the long-term cloud feedback. Here we present climate model simulations to show that the global mean cloud feedback in response to decadal temperature fluctuations varies dramatically due to time variations in the spatial pattern of sea surface temperature. We find that cloud anomalies associated with these patterns significantly modify the Earth's energy budget. Specifically, the decadal cloud feedback between the 1980s and 2000s is substantially more negative than the long-term cloud feedback. This is a result of cooling in tropical regions where air descends, relative to warming in tropical ascent regions, which strengthens low-level atmospheric stability. Under these conditions, low-level cloud cover and its reflection of solar radiation increase, despite an increase in global mean surface temperature. These results suggest that sea surface temperature pattern-induced low cloud anomalies could have contributed to the period of reduced warming between 1998 and 2013, and offer a physical explanation of why climate sensitivities estimated from recently observed trends are probably biased low.

Responses of litter-dwelling spiders and carabid beetles to varying levels and patterns of green-tree retention.

Treesearch

Juraj Halaj; Charles B. Halpern; Hoonbok Yi

2008-01-01

We studied effects of timber harvest with green-tree retention on litter-dwelling predatory arthropods (spiders and carabid beetles). Arthropods were sampled with pitfall traps at four experimental blocks in western Oregon and Washington. Within each block, arthropods were collected 5 to 7 years after treatment in five 13-ha harvest units including a control and four...

Analysis of Long-Term Temperature Variations in the Human Body.

PubMed

Dakappa, Pradeepa Hoskeri; Mahabala, Chakrapani

2015-01-01

Body temperature is a continuous physiological variable. In normal healthy adults, oral temperature is estimated to vary between 36.1°C and 37.2°C. Fever is a complex host response to many external and internal agents and is a potential contributor to many clinical conditions. Despite being one of the foremost vital signs, temperature and its analysis and variations during many pathological conditions has yet to be examined in detail using mathematical techniques. Classical fever patterns based on recordings obtained every 8-12 h have been developed. However, such patterns do not provide meaningful information in diagnosing diseases. Because fever is a host response, it is likely that there could be a unique response to specific etiologies. Continuous long-term temperature monitoring and pattern analysis using specific analytical methods developed in engineering and physics could aid in revealing unique fever responses of hosts and in different clinical conditions. Furthermore, such analysis can potentially be used as a novel diagnostic tool and to study the effect of pharmaceutical agents and other therapeutic protocols. Thus, the goal of our article is to present a comprehensive review of the recent relevant literature and analyze the current state of research regarding temperature variations in the human body.

Hemodynamic Response of the Supplementary Motor Area during Locomotor Tasks with Upright versus Horizontal Postures in Humans

PubMed Central

Obayashi, Shigeru; Nakajima, Katsumi; Hara, Yukihiro

2016-01-01

To understand cortical mechanisms related to truncal posture control during human locomotion, we investigated hemodynamic responses in the supplementary motor area (SMA) with quadrupedal and bipedal gaits using functional near-infrared spectroscopy in 10 healthy adults. The subjects performed three locomotor tasks where the degree of postural instability varied biomechanically, namely, hand-knee quadrupedal crawling (HKQuad task), upright quadrupedalism using bilateral Lofstrand crutches (UpQuad task), and typical upright bipedalism (UpBi task), on a treadmill. We measured the concentration of oxygenated hemoglobin (oxy-Hb) during the tasks. The oxy-Hb significantly decreased in the SMA during the HKQuad task, whereas it increased during the UpQuad task. No significant responses were observed during the UpBi task. Based on the degree of oxy-Hb responses, we ranked these locomotor tasks as UpQuad > UpBi > HKQuad. The order of the different tasks did not correspond with postural instability of the tasks. However, qualitative inspection of oxy-Hb time courses showed that oxy-Hb waveform patterns differed between upright posture tasks (peak-plateau-trough pattern for the UpQuad and UpBi tasks) and horizontal posture task (downhill pattern for the HKQuad task). Thus, the SMA may contribute to the control of truncal posture accompanying locomotor movements in humans. PMID:27413555

Effects of nitrogen nutrition on the synthesis and deposition of the ω-gliadins of wheat.

PubMed

Wan, Yongfang; Gritsch, Cristina Sanchis; Hawkesford, Malcolm J; Shewry, Peter R

2014-03-01

The ω-gliadin storage proteins of wheat are of interest in relation to their impact on grain processing properties and their role in food allergy, particularly the ω-5 sub-group and wheat-dependent exercise-induced anaphylaxis. The ω-gliadins are also known to be responsive to nitrogen application. This study therefore compares the effects of cultivar and nitrogen availability on the synthesis and deposition of ω-gliadins in wheat grown under field conditions in the UK, including temporal and spatial analyses at the protein and transcript levels. SDS-PAGE, western blotting and N-terminal amino acid sequencing were used to compare the patterns of ω-gliadin components in mature grain of six British wheat (Triticum aestivum) cultivars and their accumulation during the development of grain grown in field plots with varying nitrogen supply. Changes in gene expression during development were determined using real-time reverse transcription-PCR (RT-PCR). Spatial patterns of gene expression and protein accumulation were determined by in situ hybridization and immunofluorescence microscopy, respectively. Two patterns of ω-gliadins were identified in the six cultivars, including both monomeric 'gliadin' proteins and subunits present in polymeric 'glutenin' fractions. Increasing the level of nitrogen fertilizer in field plots resulted in increased expression of ω-gliadin transcripts and increased proportions of ω-5 gliadins. Nitrogen supply also affected the spatial patterns of ω-gliadin synthesis and deposition, which were differentially increased in the outer layers of the starchy endosperm with high levels of nitrogen. Wheat ω-gliadins vary in amount and composition between cultivars, and in their response to nitrogen supply. Their spatial distribution is also affected by nitrogen supply, being most highly concentrated in the sub-aleurone cells of the starchy endosperm under higher nitrogen availability.

The Patterns and Drivers of Bacterial and Fungal β-Diversity in a Typical Dryland Ecosystem of Northwest China.

PubMed

Wang, Jianming; Zhang, Tianhan; Li, Liping; Li, Jingwen; Feng, Yiming; Lu, Qi

2017-01-01

Dryland ecosystems cover more than 30% of the terrestrial area of China, while processes that shape the biogeographic patterns of bacterial and fungal β-diversity have rarely been evaluated synchronously. To compare the biogeographic patterns and its drivers of bacterial and fungal β-diversity, we collected 62 soil samples from a typical dryland region of northwest China. We assessed bacterial and fungal communities by sequencing bacterial 16S rRNA gene and fungal ITS data. Meanwhile, the β-diversity was decomposed into two components: species replacement (species turnover) and nestedness to further explore the bacterial and fungal β-diversity patterns and its causes. The results show that both bacterial and fungal β-diversity were derived almost entirely from species turnover rather than from species nestedness. Distance-decay relationships confirmed that the geographic patterns of bacterial and fungal β-diversity were significantly different. Environmental factors had the dominant influence on both the bacterial and fungal β-diversity and species turnover, however, the role of geographic distance varied across bacterial and fungal communities. Furthermore, both bacterial and fungal nestedness did not significantly respond to the environmental and geographic distance. Our findings suggest that the different response of bacterial and fungal species turnover to dispersal limitation and other, unknown processes may result in different biogeographic patterns of bacterial and fungal β-diversity in the drylands of northwest China. Together, we highlight that the drivers of β-diversity patterns vary between bacterial and fungal communities, and microbial β-diversity are driven by multiple factors in the drylands of northwest China.

Fingerprints of Modified RNA Bases from Deep Sequencing Profiles.

PubMed

Kietrys, Anna M; Velema, Willem A; Kool, Eric T

2017-11-29

Posttranscriptional modifications of RNA bases are not only found in many noncoding RNAs but have also recently been identified in coding (messenger) RNAs as well. They require complex and laborious methods to locate, and many still lack methods for localized detection. Here we test the ability of next-generation sequencing (NGS) to detect and distinguish between ten modified bases in synthetic RNAs. We compare ultradeep sequencing patterns of modified bases, including miscoding, insertions and deletions (indels), and truncations, to unmodified bases in the same contexts. The data show widely varied responses to modification, ranging from no response, to high levels of mutations, insertions, deletions, and truncations. The patterns are distinct for several of the modifications, and suggest the future use of ultradeep sequencing as a fingerprinting strategy for locating and identifying modifications in cellular RNAs.

Compassion: An Evolutionary Analysis and Empirical Review

PubMed Central

Goetz, Jennifer L.; Keltner, Dacher; Simon-Thomas, Emiliana

2010-01-01

What is compassion? And how did it evolve? In this review, we integrate three evolutionary arguments that converge on the hypothesis that compassion evolved as a distinct affective experience whose primary function is to facilitate cooperation and protection of the weak and those who suffer. Our empirical review reveals compassion to have distinct appraisal processes attuned to undeserved suffering, distinct signaling behavior related to caregiving patterns of touch, posture, and vocalization, and a phenomenological experience and physiological response that orients the individual to social approach. This response profile of compassion differs from those of distress, sadness, and love, suggesting that compassion is indeed a distinct emotion. We conclude by considering how compassion shapes moral judgment and action, how it varies across different cultures, and how it may engage specific patterns of neural activation, as well as emerging directions of research. PMID:20438142

Delayed response and biosonar perception explain movement coordination in trawling bats.

PubMed

Giuggioli, Luca; McKetterick, Thomas J; Holderied, Marc

2015-03-01

Animal coordinated movement interactions are commonly explained by assuming unspecified social forces of attraction, repulsion and alignment with parameters drawn from observed movement data. Here we propose and test a biologically realistic and quantifiable biosonar movement interaction mechanism for echolocating bats based on spatial perceptual bias, i.e. actual sound field, a reaction delay, and observed motor constraints in speed and acceleration. We found that foraging pairs of bats flying over a water surface swapped leader-follower roles and performed chases or coordinated manoeuvres by copying the heading a nearby individual has had up to 500 ms earlier. Our proposed mechanism based on the interplay between sensory-motor constraints and delayed alignment was able to recreate the observed spatial actor-reactor patterns. Remarkably, when we varied model parameters (response delay, hearing threshold and echolocation directionality) beyond those observed in nature, the spatio-temporal interaction patterns created by the model only recreated the observed interactions, i.e. chases, and best matched the observed spatial patterns for just those response delays, hearing thresholds and echolocation directionalities found to be used by bats. This supports the validity of our sensory ecology approach of movement coordination, where interacting bats localise each other by active echolocation rather than eavesdropping.

Season-modulated responses of Neotropical bats to forest fragmentation.

PubMed

Ferreira, Diogo F; Rocha, Ricardo; López-Baucells, Adrià; Farneda, Fábio Z; Carreiras, João M B; Palmeirim, Jorge M; Meyer, Christoph F J

2017-06-01

Seasonality causes fluctuations in resource availability, affecting the presence and abundance of animal species. The impacts of these oscillations on wildlife populations can be exacerbated by habitat fragmentation. We assessed differences in bat species abundance between the wet and dry season in a fragmented landscape in the Central Amazon characterized by primary forest fragments embedded in a secondary forest matrix. We also evaluated whether the relative importance of local vegetation structure versus landscape characteristics (composition and configuration) in shaping bat abundance patterns varied between seasons. Our working hypotheses were that abundance responses are species as well as season specific, and that in the wet season, local vegetation structure is a stronger determinant of bat abundance than landscape-scale attributes. Generalized linear mixed-effects models in combination with hierarchical partitioning revealed that relationships between species abundances and local vegetation structure and landscape characteristics were both season specific and scale dependent. Overall, landscape characteristics were more important than local vegetation characteristics, suggesting that landscape structure is likely to play an even more important role in landscapes with higher fragment-matrix contrast. Responses varied between frugivores and animalivores. In the dry season, frugivores responded more to compositional metrics, whereas during the wet season, local and configurational metrics were more important. Animalivores showed similar patterns in both seasons, responding to the same group of metrics in both seasons. Differences in responses likely reflect seasonal differences in the phenology of flowering and fruiting between primary and secondary forests, which affected the foraging behavior and habitat use of bats. Management actions should encompass multiscale approaches to account for the idiosyncratic responses of species to seasonal variation in resource abundance and consequently to local and landscape scale attributes.

Land surface phenological responses to land use and climate variation in a changing Central Asia

NASA Astrophysics Data System (ADS)

Kariyeva, Jahan

During the last few decades Central Asia has experienced widespread changes in land cover and land use following the socio-economic and institutional transformations of the region catalyzed by the USSR collapse in 1991. The decade-long drought events and steadily increasing temperature regimes in the region came on top of these institutional transformations, affecting the long term and landscape scale vegetation responses. This research is based on the need to better understand the potential ecological and policy implications of climate variation and land use practices in the contexts of landscape-scale changes dynamics and variability patterns of land surface phenology responses in Central Asia. The land surface phenology responses -- the spatio-temporal dynamics of terrestrial vegetation derived from the remotely sensed data -- provide measurements linked to the timing of vegetation growth cycles (e.g., start of growing season) and total vegetation productivity over the growing season, which are used as a proxy for the assessment of effects of variations in environmental settings. Local and regional scale assessment of the before and after the USSR collapse vegetation response patterns in the natural and agricultural systems of the Central Asian drylands was conducted to characterize newly emerging links (since 1991) between coupled human and natural systems, e.g., socio-economic and policy drivers of altered land and water use and distribution patterns. Spatio-temporal patterns of bioclimatic responses were examined to determine how phenology is associated with temperature and precipitation in different land use types, including rainfed and irrigated agricultural types. Phenological models were developed to examine relationship between environmental drivers and effect of their altitudinal and latitudinal gradients on the broad-scale vegetation response patterns in non-cropland ecosystems of the desert, steppe, and mountainous regional landscapes of Central Asia. The study results demonstrated that the satellite derived measurements of temporal cycles of vegetation greenness and productivity data was a valuable bioclimatic integrator of climatic and land use variation in Central Asia. The synthesis of broad-scale phenological changes in Central Asia showed that linkages of natural and human systems vary across space and time comprising complex and tightly integrated patterns and processes that are not evident when studied separately.

Acute stress evokes sexually dimorphic, stressor-specific patterns of neural activation across multiple limbic brain regions in adult rats.

PubMed

Sood, Ankit; Chaudhari, Karina; Vaidya, Vidita A

2018-03-01

Stress enhances the risk for psychiatric disorders such as anxiety and depression. Stress responses vary across sex and may underlie the heightened vulnerability to psychopathology in females. Here, we examined the influence of acute immobilization stress (AIS) and a two-day short-term forced swim stress (FS) on neural activation in multiple cortical and subcortical brain regions, implicated as targets of stress and in the regulation of neuroendocrine stress responses, in male and female rats using Fos as a neural activity marker. AIS evoked a sex-dependent pattern of neural activation within the cingulate and infralimbic subdivisions of the medial prefrontal cortex (mPFC), lateral septum (LS), habenula, and hippocampal subfields. The degree of neural activation in the mPFC, LS, and habenula was higher in males. Female rats exhibited reduced Fos positive cell numbers in the dentate gyrus hippocampal subfield, an effect not observed in males. We addressed whether the sexually dimorphic neural activation pattern noted following AIS was also observed with the short-term stress of FS. In the paraventricular nucleus of the hypothalamus and the amygdala, FS similar to AIS resulted in robust increases in neural activation in both sexes. The pattern of neural activation evoked by FS was distinct across sexes, with a heightened neural activation noted in the prelimbic mPFC subdivision and hippocampal subfields in females and differed from the pattern noted with AIS. This indicates that the sex differences in neural activation patterns observed within stress-responsive brain regions are dependent on the nature of stressor experience.

Shed a light in fatigue detection with near-infrared spectroscopy during long-lasting driving

NASA Astrophysics Data System (ADS)

Gao, Yuan; Pan, Boan; Li, Kai; Li, Ting

2016-03-01

Fatigue driving is one of the leading roles to induce traffic accident and injury, which urgently desires a novel technique to monitor the fatigue level at driving. Functional near infrared spectroscopy (fNIRS) is capable of noninvasive monitoring brain-activities-related hemodynamic responses. Here, we developed a fINRS imager and setup a classic psychological experiment to trigger visual divided attention which varied responding to driving fatigue, and attempted to record the drive-fatigue-level correlated hemodynamic response in the prefrontal cortex. 7 volunteers were recruited to take 7 hours driving and the experimental test was repeated every 1 hour and 8 times in total. The hemodynamic response were extracted and graphed with pseudo image. The analysis on the relationship between the fNIRS-measured hemodynamic response and fatigue level finally displayed that the oxyhemoglobin concentration in one channel of left prefrontal lobe increased with driving duration in significant correlation. And the spatial pattern of hemodynamic response in the prefrontal lobe varied with driving duration as well. The findings indicated the potential of fNIRSmeasured hemodynamic index in some sensitive spot of prefrontal lobe as a driving fatigue indicator and the promising use of fNIRS in traffic safety field.

Controlling placement of nonspherical (boomerang) colloids in nematic cells with photopatterned director

NASA Astrophysics Data System (ADS)

Peng, Chenhui; Turiv, Taras; Zhang, Rui; Guo, Yubing; Shiyanovskii, Sergij V.; Wei, Qi-Huo; de Pablo, Juan; Lavrentovich, Oleg D.

2017-01-01

Placing colloidal particles in predesigned sites represents a major challenge of the current state-of-the-art colloidal science. Nematic liquid crystals with spatially varying director patterns represent a promising approach to achieve a well-controlled placement of colloidal particles thanks to the elastic forces between the particles and the surrounding landscape of molecular orientation. Here we demonstrate how the spatially varying director field can be used to control placement of non-spherical particles of boomerang shape. The boomerang colloids create director distortions of a dipolar symmetry. When a boomerang particle is placed in a periodic splay-bend director pattern, it migrates towards the region of a maximum bend. The behavior is contrasted to that one of spherical particles with normal surface anchoring, which also produce dipolar director distortions, but prefer to compartmentalize into the regions with a maximum splay. The splay-bend periodic landscape thus allows one to spatially separate these two types of particles. By exploring overdamped dynamics of the colloids, we determine elastic driving forces responsible for the preferential placement. Control of colloidal locations through patterned molecular orientation can be explored for future applications in microfluidic, lab on a chip, sensing and sorting devices.

Controlling placement of nonspherical (boomerang) colloids in nematic cells with photopatterned director.

PubMed

Peng, Chenhui; Turiv, Taras; Zhang, Rui; Guo, Yubing; Shiyanovskii, Sergij V; Wei, Qi-Huo; de Pablo, Juan; Lavrentovich, Oleg D

2017-01-11

Placing colloidal particles in predesigned sites represents a major challenge of the current state-of-the-art colloidal science. Nematic liquid crystals with spatially varying director patterns represent a promising approach to achieve a well-controlled placement of colloidal particles thanks to the elastic forces between the particles and the surrounding landscape of molecular orientation. Here we demonstrate how the spatially varying director field can be used to control placement of non-spherical particles of boomerang shape. The boomerang colloids create director distortions of a dipolar symmetry. When a boomerang particle is placed in a periodic splay-bend director pattern, it migrates towards the region of a maximum bend. The behavior is contrasted to that one of spherical particles with normal surface anchoring, which also produce dipolar director distortions, but prefer to compartmentalize into the regions with a maximum splay. The splay-bend periodic landscape thus allows one to spatially separate these two types of particles. By exploring overdamped dynamics of the colloids, we determine elastic driving forces responsible for the preferential placement. Control of colloidal locations through patterned molecular orientation can be explored for future applications in microfluidic, lab on a chip, sensing and sorting devices.

Feedback-driven response to multidecadal climatic variability at an alpine treeline

USGS Publications Warehouse

Alftine, K.J.; Malanson, G.P.; Fagre, D.B.

2003-01-01

The Pacific Decadal Oscillation (PDO) has significant climatological and ecological effects in northwestern North America. Its possible effects and their modification by feedbacks are examined in the forest-tundra ecotone in Glacier National Park, Montana, USA. Tree ring samples were collected to estimate establishment dates in 10 quadrats. Age-diameter regressions were used to estimate the ages of uncored trees. The temporal pattern of establishment and survival was compared to the pattern of the PDO. A wave of establishment began in the mid-1940s, rose to a peak rate in the mid-1970s, and dropped precipitously beginning ca. 1980 to near zero for the 1990s. The period of establishment primarily coincided with the negative phase of the PDO, but the establishment and survival pattern is not correlated with the PDO index. The pattern indicates a period during which establishment was possible and was augmented by positive feedback from surviving trees. Snow may be the most important factor in the feedback, but studies indicate that its effects vary locally. Spatially differentiated analyses of decadal or longer periodicity may elucidate responses to climatic variation. ?? 2003 by V. H. Winston and Son, Inc. All rights reserved.

Old but Still Relevant: High Resolution Electrophoresis and Immunofixation in Multiple Myeloma.

PubMed

Misra, Aroonima; Mishra, Jyoti; Chandramohan, Jagan; Sharma, Atul; Raina, Vinod; Kumar, Rajive; Soni, Sushant; Chopra, Anita

2016-03-01

High resolution electrophoresis (HRE) and immunofixation (IFX) of serum and urine are integral to the diagnostic work-up of multiple myeloma. Unusual electrophoresis patterns are common and may be misinterpreted. Though primarily the responsibility of the hematopathologist, clinicians who are responsible for managing myelomas may benefit from knowledge of these. In this review article we intend to discuss the patterns and importance of electrophoresis in present day scenario. Patterns of HRE and IFX seen in our laboratory over the past 15 years were studied. Monoclonal proteins are seen on HRE as sharply defined bands, sometimes two, lying from γ- to α-globulin regions on a background of normal, increased or decreased polyclonal γ-globulins, showing HRE to be a rapid and dependable method of detecting M-protein in serum or urine. Immunofixation complements HRE and due to its greater sensitivity, is able to pick up small or light chain bands, not apparent on electrophoresis, including biclonal disease even when electrophoresis shows only one M-band. Special features liable to misinterpretation are discussed. Familiarity with the interpretation of the varied patterns seen in health and disease is essential for providing dependable laboratory support in the management of multiple myeloma.

Looking into Candida albicans infection, host response, and antifungal strategies.

PubMed

Wang, Yan

2015-01-01

Candida albicans, a commonly encountered fungal pathogen, causes diseases varying from superficial mucosal complaints to life-threatening systemic disorders. Among the virulence traits of C. albicans, yeast-to-hypha transition is most widely acknowledged. Host innate immunity to C. albicans critically requires pattern recognition receptors (PRRs), and defence against C. albicans infection is provided by an exquisite interplay between the innate and adaptive arms of the host immune system.

Intracellular glucocorticoid receptors in spleen, but not skin, vary seasonally in wild house sparrows (Passer domesticus)

PubMed Central

Lattin, Christine R.; Waldron-Francis, K.; Romero, L. Michael

2013-01-01

Over the short-term and at physiological doses, acute increases in corticosterone (CORT) titres can enhance immune function. There are predictable seasonal patterns in both circulating CORT and immune function across many animal species, but whether CORT receptor density in immune tissues varies seasonally is currently unknown. Using radioligand binding assays, we examined changes in concentrations of glucocorticoid receptors (GR) and mineralocorticoid receptors (MR) in spleen and skin in wild-caught house sparrows in Massachusetts during six different life-history stages: moult, early winter, late winter, pre-egg-laying, breeding and late breeding. Splenic GR and MR binding were highest during the pre-laying period. This may help animals respond to immune threats through increased lymphocyte proliferation and/or an increase in delayed-type hypersensitivity reactions, both of which CORT can stimulate and in which spleen is involved. A decrease in splenic GR and MR during the late breeding period coincides with low baseline and stress-induced CORT, suggesting immune function in spleen may be relatively CORT-independent during this period. We saw no seasonal patterns in GR or MR in skin, suggesting skin's response to CORT is modulated primarily via changes in circulating CORT titres and/or via local production of CORT in response to wounding and other noxious stimuli. PMID:23407837

Impacts of weather on long-term patterns of plant richness and diversity vary with location and management

USGS Publications Warehouse

Jonas, Jayne L.; Buhl, Deborah A.; Symstad, Amy J.

2015-01-01

Better understanding the influence of precipitation and temperature on plant assemblages is needed to predict the effects of climate change. Many studies have examined the relationship between plant productivity and weather (primarily precipitation), but few have directly assessed the relationship between plant richness or diversity and weather despite their increased use as metrics of ecosystem condition. We focus on the grasslands of central North America, which are characterized by high temporal climatic variability. Over the next 100 years, these grasslands are predicted to experience further increased variability in growing season precipitation, as well as increased temperatures, due to global climate change. We assess 1) the portion of interannual variability of richness and diversity explained by weather, 2) how relationships between these metrics and weather vary among plant assemblages, and 3) which aspects of weather best explain temporal variability. We used an information-theoretic approach to assess relationships between long-term plant richness and diversity patterns and a priori weather covariates using six datasets from four grasslands. Weather explained up to 49% and 63% of interannual variability in total plant species richness and diversity, respectively. However, richness and diversity responses to specific weather variables varied both among sites and among experimental treatments within sites. In general, we found many instances in which temperature was of equal or greater importance as precipitation, as well as evidence of the importance of lagged effects and precipitation or temperature variability. Although precipitation has been shown to be a key driver of productivity in grasslands, our results indicate that increasing temperatures alone, without substantial changes in precipitation patterns, could have measurable effects on Great Plains grassland plant assemblages and biodiversity metrics. Our results also suggest that richness and diversity will respond in unique ways to changing climate and management can affect these responses; additional research and monitoring will be essential for further understanding of these complex relationships.Read More: http://www.esajournals.org/doi/abs/10.1890/14-1989.1

Impacts of weather on long-term patterns of plant richness and diversity vary with location and management.

PubMed

Jonas, Jayne L; Buhl, Deborah A; Symstad, Amy J

2015-09-01

Better understanding the influence of precipitation and temperature on plant assemblages is needed to predict the effects of climate change. Many studies have examined the relationship between plant productivity and weather (primarily precipitation), but few have directly assessed the relationship between plant richness or diversity and weather despite their increased use as metrics of ecosystem condition. We focus on the grasslands of central North America, which are characterized by high temporal climatic variability. Over the next 100 years, these grasslands are predicted to experience further increased variability in growing season precipitation, as well as increased temperatures, due to global climate change. We assess the portion of interannual variability of richness and diversity explained by weather, how relationships between these metrics and weather vary among plant assemblages, and which aspects of weather best explain temporal variability. We used an information-theoretic approach to assess relationships between long-term plant richness and diversity patterns and a priori weather covariates using six data sets from four grasslands. Weather explained up to 49% and 63% of interannual variability in total plant species richness and diversity, respectively. However, richness and diversity responses to specific weather variables varied both among sites and among experimental treatments within sites. In general, we found many instances in which temperature was of equal or greater importance as precipitation, as well as evidence of the importance of lagged effects and precipitation or temperature variability. Although precipitation has been shown to be a key driver of productivity in grasslands, our results indicate that increasing temperatures alone, without substantial changes in precipitation patterns, could have measurable effects on Great Plains grassland plant assemblages and biodiversity metrics. Our results also suggest that richness and diversity will respond in unique ways to changing climate and management can affect these responses; additional research and monitoring will be essential for further understanding of these complex relationships.

Torsion sensing based on patterned piezoelectric beams

NASA Astrophysics Data System (ADS)

Cha, Youngsu; You, Hangil

2018-03-01

In this study, we investigated the sensing characteristics of piezoelectric beams under torsional loads. We used partially patterned piezoelectric beams to sense torsion. In particular, the piezoelectric patches are located symmetrically with respect to the line of the shear center of the beam. The patterned piezoelectric beam is modeled as a slender beam, and its electrical responses are obtained by piezoelectric electromechanical equations. To validate the modeling framework, experiments are performed using a setup that forces pure torsional deformation. Three different geometric configurations of the patterned piezoelectric layer are used for the experiments. The frequency and amplitude of the forced torsional load are systematically varied in order to study the behavior of the piezoelectric sensor. Experimental results demonstrate that two voltage outputs of the piezoelectric beam are approximately out of phase with identical amplitude. Moreover, the length of the piezoelectric layers has a significant influence on the sensing properties. Our theoretical predictions using the model support the experimental findings.

Age differences in visual search for compound patterns: long- versus short-range grouping.

PubMed

Burack, J A; Enns, J T; Iarocci, G; Randolph, B

2000-11-01

Visual search for compound patterns was examined in observers aged 6, 8, 10, and 22 years. The main question was whether age-related improvement in search rate (response time slope over number of items) was different for patterns defined by short- versus long-range spatial relations. Perceptual access to each type of relation was varied by using elements of same contrast (easy to access) or mixed contrast (hard to access). The results showed large improvements with age in search rate for long-range targets; search rate for short-range targets was fairly constant across age. This pattern held regardless of whether perceptual access to a target was easy or hard, supporting the hypothesis that different processes are involved in perceptual grouping at these two levels. The results also point to important links between ontogenic and microgenic change in perception (H. Werner, 1948, 1957).

Modulating capacitive response of MoS2 flake by controlled nanostructuring through focused laser irradiation.

PubMed

Rani, Renu; Kundu, Anirban; Balal, Mohammad; Sheet, Goutam; Hazra, Kiran Shankar

2018-08-24

Unlike graphene nanostructures, various physical properties of nanostructured MoS 2 have remained unexplored due to the lack of established fabrication routes. Herein, we have reported unique electrostatic properties of MoS 2 nanostructures, fabricated in a controlled manner of different geometries on 2D flake by using focused laser irradiation technique. Electrostatic force microscopy has been carried out on MoS 2 nanostructures by varying tip bias voltage and lift height. The analysis depicts no contrast flip in phase image of the patterned nanostructure due to the absence of free surface charges. However, prominent change in phase shift at the patterned area is observed. Such contrast changes signify the capacitive interaction between tip and nanostructures at varying tip bias voltage and lift height, irrespective of their shape and size. Such unperturbed capacitive behavior of the MoS 2 nanostructures offer modulation of capacitance in periodic array on 2D MoS 2 flake for potential application in capacitive devices.

Positive psychological effects of space missions

NASA Astrophysics Data System (ADS)

Ritsher, Jennifer Boyd; Ihle, Eva C.; Kanas, Nick

2005-07-01

Being in space is a powerful experience that can have an enduring, positive impact on the psychological well-being of astronauts and cosmonauts. We sought to examine the frequency, intensity and distribution of such salutogenic experiences among persons who have flown in space, using a questionnaire we developed based on the scientific literature and first person accounts. All participants reported positive effects of being in space, but the degree of change varied widely, and some experiences were particularly common. Three of our five predicted attitude behavior relationships were supported by the data. Response patterns did not vary according to demographics or time in space. Cluster analysis yielded two groups of participants. One group was generally more reactive and also placed a higher priority on perceptions of space than did the other group. We conclude that positive experiences are common among space travelers and seem to cluster into meaningful patterns that may be consequential for Mars missions. We consider the possible selection, training, and monitoring issues raised by our findings.

Yardangs in the Qaidam Basin, northwestern China: Distribution and morphology

NASA Astrophysics Data System (ADS)

Li, Jiyan; Dong, Zhibao; Qian, Guangqiang; Zhang, Zhengcai; Luo, Wanyin; Lu, Junfeng; Wang, Meng

2016-03-01

The northwestern Qaidam Basin exposes one of the largest and highest elevation yardang fields on Earth. The aim of the present study was to describe the distribution and morphology of these yardangs, and analyze the factors responsible for the distribution pattern of these aeolian landforms. The yardang fields are bounded by piedmont alluvial-diluvial fans from the mountain ranges surrounding the basin, except in the south, where they are bounded by dune fields, dry salt flats, lakes, and rivers. This distribution pattern can be attributed to regional tectogenesis and its corresponding environmental impacts. The morphology of the yardangs varies considerably in response to the diverse factors that control their formation and evolution. Long-ridge yardangs are mainly located in the northernmost part of the yardang field, and the long ridges are gradually dissected into smaller ridges in the downwind direction. Further downwind, the convergence of northerly and northwesterly winds and the effects of temporary runoff cause the ridges to gradually transition into mesa yardangs. Saw-toothed crests, and conical and pyramidal yardangs, occur in groups on folded brachyanticlinal structures. Typical whaleback yardangs are found in the southeast, at the northern margin of Dabuxun Lake. Morphological parameters vary among the yardang types. The orientation of the yardangs in the northernmost area is nearly N-S, with a transition towards NW-SE in the southernmost area in response to a change in the dominant wind direction that results from the orientations and positions of the mountain ranges that surround the basin.

Effects of elevated atmospheric carbon dioxide on biomass and carbon accumulation in a model regenerating longleaf pine community.

PubMed

Runion, G B; Davis, M A; Pritchard, S G; Prior, S A; Mitchell, R J; Torbert, H A; Rogers, H H; Dute, R R

2006-01-01

Plant species vary in response to atmospheric CO2 concentration due to differences in physiology, morphology, phenology, and symbiotic relationships. These differences make it very difficult to predict how plant communities will respond to elevated CO2. Such information is critical to furthering our understanding of community and ecosystem responses to global climate change. To determine how a simple plant community might respond to elevated CO2, a model regenerating longleaf pine community composed of five species was exposed to two CO2 regimes (ambient, 365 micromol mol(-1) and elevated, 720 micromol mol(-1)) for 3 yr. Total above- and belowground biomass was 70 and 49% greater, respectively, in CO2-enriched plots. Carbon (C) content followed a response pattern similar to biomass, resulting in a significant increase of 13.8 Mg C ha(-1) under elevated CO2. Responses of individual species, however, varied. Longleaf pine (Pinus palustris Mill.) was primarily responsible for the positive response to CO2 enrichment. Wiregrass (Aristida stricta Michx.), rattlebox (Crotalaria rotundifolia Walt. Ex Gmel.), and butterfly weed (Asclepias tuberosa L.) exhibited negative above- and belowground biomass responses to elevated CO2, while sand post oak (Quercus margaretta Ashe) did not differ significantly between CO2 treatments. As with pine, C content followed patterns similar to biomass. Elevated CO2 resulted in alterations in community structure. Longleaf pine comprised 88% of total biomass in CO2-enriched plots, but only 76% in ambient plots. In contrast, wiregrass, rattlebox, and butterfly weed comprised 19% in ambient CO2 plots, but only 8% under high CO2. Therefore, while longleaf pine may perform well in a high CO2 world, other members of this community may not compete as well, which could alter community function. Effects of elevated CO2 on plant communities are complex, dynamic, and difficult to predict, clearly demonstrating the need for more research in this important area of global change science.

Functional traits variation explains the distribution of Aextoxicon punctatum (Aextoxicaceae) in pronounced moisture gradients within fog-dependent forest fragments.

PubMed

Salgado-Negret, Beatriz; Canessa, Rafaella; Valladares, Fernando; Armesto, Juan J; Pérez, Fernanda

2015-01-01

Climate change and fragmentation are major threats to world forests. Understanding how functional traits related to drought tolerance change across small-scale, pronounced moisture gradients in fragmented forests is important to predict species' responses to these threats. In the case of Aextoxicon punctatum, a dominant canopy tree in fog-dependent rain forest patches in semiarid Chile, we explored how the magnitude, variability and correlation patterns of leaf and xylem vessel traits and hydraulic conductivity varied across soil moisture (SM) gradients established within and among forest patches of different size, which are associated with differences in tree establishment and mortality patterns. Leaf traits varied across soil-moisture gradients produced by fog interception. Trees growing at drier leeward edges showed higher leaf mass per area, trichome and stomatal density than trees from the wetter core and windward zones. In contrast, xylem vessel traits (vessels diameter and density) did not vary producing loss of hydraulic conductivity at drier leeward edges. We also detected higher levels of phenotypic integration and variability at leeward edges. The ability of A. punctatum to modify leaf traits in response to differences in SM availability established over short distances (<500 m) facilitates its persistence in contrasting microhabitats within forest patches. However, xylem anatomy showed limited plasticity, which increases cavitation risk at leeward edges. Greater patch fragmentation, together with fluctuations in irradiance and SM in small patches, could result in higher risk of drought-related tree mortality, with profound impacts on hydrological balances at the ecosystem scale.

Functional traits variation explains the distribution of Aextoxicon punctatum (Aextoxicaceae) in pronounced moisture gradients within fog-dependent forest fragments

PubMed Central

Salgado-Negret, Beatriz; Canessa, Rafaella; Valladares, Fernando; Armesto, Juan J.; Pérez, Fernanda

2015-01-01

Climate change and fragmentation are major threats to world forests. Understanding how functional traits related to drought tolerance change across small-scale, pronounced moisture gradients in fragmented forests is important to predict species’ responses to these threats. In the case of Aextoxicon punctatum, a dominant canopy tree in fog-dependent rain forest patches in semiarid Chile, we explored how the magnitude, variability and correlation patterns of leaf and xylem vessel traits and hydraulic conductivity varied across soil moisture (SM) gradients established within and among forest patches of different size, which are associated with differences in tree establishment and mortality patterns. Leaf traits varied across soil-moisture gradients produced by fog interception. Trees growing at drier leeward edges showed higher leaf mass per area, trichome and stomatal density than trees from the wetter core and windward zones. In contrast, xylem vessel traits (vessels diameter and density) did not vary producing loss of hydraulic conductivity at drier leeward edges. We also detected higher levels of phenotypic integration and variability at leeward edges. The ability of A. punctatum to modify leaf traits in response to differences in SM availability established over short distances (<500 m) facilitates its persistence in contrasting microhabitats within forest patches. However, xylem anatomy showed limited plasticity, which increases cavitation risk at leeward edges. Greater patch fragmentation, together with fluctuations in irradiance and SM in small patches, could result in higher risk of drought-related tree mortality, with profound impacts on hydrological balances at the ecosystem scale. PMID:26257746

Modeling and measuring the visual detection of ecologically relevant motion by an Anolis lizard.

PubMed

Pallus, Adam C; Fleishman, Leo J; Castonguay, Philip M

2010-01-01

Motion in the visual periphery of lizards, and other animals, often causes a shift of visual attention toward the moving object. This behavioral response must be more responsive to relevant motion (predators, prey, conspecifics) than to irrelevant motion (windblown vegetation). Early stages of visual motion detection rely on simple local circuits known as elementary motion detectors (EMDs). We presented a computer model consisting of a grid of correlation-type EMDs, with videos of natural motion patterns, including prey, predators and windblown vegetation. We systematically varied the model parameters and quantified the relative response to the different classes of motion. We carried out behavioral experiments with the lizard Anolis sagrei and determined that their visual response could be modeled with a grid of correlation-type EMDs with a spacing parameter of 0.3 degrees visual angle, and a time constant of 0.1 s. The model with these parameters gave substantially stronger responses to relevant motion patterns than to windblown vegetation under equivalent conditions. However, the model is sensitive to local contrast and viewer-object distance. Therefore, additional neural processing is probably required for the visual system to reliably distinguish relevant from irrelevant motion under a full range of natural conditions.

Binaural sensitivity changes between cortical on and off responses

PubMed Central

Dahmen, Johannes C.; King, Andrew J.; Schnupp, Jan W. H.

2011-01-01

Neurons exhibiting on and off responses with different frequency tuning have previously been described in the primary auditory cortex (A1) of anesthetized and awake animals, but it is unknown whether other tuning properties, including sensitivity to binaural localization cues, also differ between on and off responses. We measured the sensitivity of A1 neurons in anesthetized ferrets to 1) interaural level differences (ILDs), using unmodulated broadband noise with varying ILDs and average binaural levels, and 2) interaural time delays (ITDs), using sinusoidally amplitude-modulated broadband noise with varying envelope ITDs. We also assessed fine-structure ITD sensitivity and frequency tuning, using pure-tone stimuli. Neurons most commonly responded to stimulus onset only, but purely off responses and on-off responses were also recorded. Of the units exhibiting significant binaural sensitivity nearly one-quarter showed binaural sensitivity in both on and off responses, but in almost all (∼97%) of these units the binaural tuning of the on responses differed significantly from that seen in the off responses. Moreover, averaged, normalized ILD and ITD tuning curves calculated from all units showing significant sensitivity to binaural cues indicated that on and off responses displayed different sensitivity patterns across the population. A principal component analysis of ITD response functions suggested a continuous cortical distribution of binaural sensitivity, rather than discrete response classes. Rather than reflecting a release from inhibition without any functional significance, we propose that binaural off responses may be important to cortical encoding of sound-source location. PMID:21562191

Measuring multielectron beam imaging fidelity with a signal-to-noise ratio analysis

NASA Astrophysics Data System (ADS)

Mukhtar, Maseeh; Bunday, Benjamin D.; Quoi, Kathy; Malloy, Matt; Thiel, Brad

2016-07-01

Java Monte Carlo Simulator for Secondary Electrons (JMONSEL) simulations are used to generate expected imaging responses of chosen test cases of patterns and defects with the ability to vary parameters for beam energy, spot size, pixel size, and/or defect material and form factor. The patterns are representative of the design rules for an aggressively scaled FinFET-type design. With these simulated images and resulting shot noise, a signal-to-noise framework is developed, which relates to defect detection probabilities. Additionally, with this infrastructure, the effect of detection chain noise and frequency-dependent system response can be made, allowing for targeting of best recipe parameters for multielectron beam inspection validation experiments. Ultimately, these results should lead to insights into how such parameters will impact tool design, including necessary doses for defect detection and estimations of scanning speeds for achieving high throughput for high-volume manufacturing.

Design a New Strategy Based on Nanoparticle-Enhanced Chemiluminescence Sensor Array for Biothiols Discrimination

NASA Astrophysics Data System (ADS)

Shahrajabian, Maryam; Hormozi-Nezhad, M. Reza

2016-08-01

Array-based sensor is an interesting approach that suggests an alternative to expensive analytical methods. In this work, we introduce a novel, simple, and sensitive nanoparticle-based chemiluminescence (CL) sensor array for discrimination of biothiols (e.g., cysteine, glutathione and glutathione disulfide). The proposed CL sensor array is based on the CL efficiencies of four types of enhanced nanoparticle-based CL systems. The intensity of CL was altered to varying degrees upon interaction with biothiols, producing unique CL response patterns. These distinct CL response patterns were collected as “fingerprints” and were then identified through chemometric methods, including linear discriminant analysis (LDA) and hierarchical cluster analysis (HCA). The developed array was able to successfully differentiate between cysteine, glutathione and glutathione disulfide in a wide concentration range. Moreover, it was applied to distinguish among the above analytes in human plasma.

UV laser-ablated surface textures as potential regulator of cellular response.

PubMed

Chandra, Prafulla; Lai, Karen; Sung, Hak-Joon; Murthy, N Sanjeeva; Kohn, Joachim

2010-06-01

Textured surfaces obtained by UV laser ablation of poly(ethylene terephthalate) films were used to study the effect of shape and spacing of surface features on cellular response. Two distinct patterns, cones and ripples with spacing from 2 to 25 μm, were produced. Surface features with different shapes and spacings were produced by varying pulse repetition rate, laser fluence, and exposure time. The effects of the surface texture parameters, i.e., shape and spacing, on cell attachment, proliferation, and morphology of neonatal human dermal fibroblasts and mouse fibroblasts were studied. Cell attachment was the highest in the regions with cones at ∼4 μm spacing. As feature spacing increased, cell spreading decreased, and the fibroblasts became more circular, indicating a stress-mediated cell shrinkage. This study shows that UV laser ablation is a useful alternative to lithographic techniques to produce surface patterns for controlling cell attachment and growth on biomaterial surfaces.

Compassion: an evolutionary analysis and empirical review.

PubMed

Goetz, Jennifer L; Keltner, Dacher; Simon-Thomas, Emiliana

2010-05-01

What is compassion? And how did it evolve? In this review, we integrate 3 evolutionary arguments that converge on the hypothesis that compassion evolved as a distinct affective experience whose primary function is to facilitate cooperation and protection of the weak and those who suffer. Our empirical review reveals compassion to have distinct appraisal processes attuned to undeserved suffering; distinct signaling behavior related to caregiving patterns of touch, posture, and vocalization; and a phenomenological experience and physiological response that orients the individual to social approach. This response profile of compassion differs from those of distress, sadness, and love, suggesting that compassion is indeed a distinct emotion. We conclude by considering how compassion shapes moral judgment and action, how it varies across different cultures, and how it may engage specific patterns of neural activation, as well as emerging directions of research. (c) 2010 APA, all rights reserved.

Behavioral and Single-Neuron Sensitivity to Millisecond Variations in Temporally Patterned Communication Signals

PubMed Central

Baker, Christa A.; Ma, Lisa; Casareale, Chelsea R.

2016-01-01

In many sensory pathways, central neurons serve as temporal filters for timing patterns in communication signals. However, how a population of neurons with diverse temporal filtering properties codes for natural variation in communication signals is unknown. Here we addressed this question in the weakly electric fish Brienomyrus brachyistius, which varies the time intervals between successive electric organ discharges to communicate. These fish produce an individually stereotyped signal called a scallop, which consists of a distinctive temporal pattern of ∼8–12 electric pulses. We manipulated the temporal structure of natural scallops during behavioral playback and in vivo electrophysiology experiments to probe the temporal sensitivity of scallop encoding and recognition. We found that presenting time-reversed, randomized, or jittered scallops increased behavioral response thresholds, demonstrating that fish's electric signaling behavior was sensitive to the precise temporal structure of scallops. Next, using in vivo intracellular recordings and discriminant function analysis, we found that the responses of interval-selective midbrain neurons were also sensitive to the precise temporal structure of scallops. Subthreshold changes in membrane potential recorded from single neurons discriminated natural scallops from time-reversed, randomized, and jittered sequences. Pooling the responses of multiple neurons improved the discriminability of natural sequences from temporally manipulated sequences. Finally, we found that single-neuron responses were sensitive to interindividual variation in scallop sequences, raising the question of whether fish may analyze scallop structure to gain information about the sender. Collectively, these results demonstrate that a population of interval-selective neurons can encode behaviorally relevant temporal patterns with millisecond precision. SIGNIFICANCE STATEMENT The timing patterns of action potentials, or spikes, play important roles in representing information in the nervous system. However, how these temporal patterns are recognized by downstream neurons is not well understood. Here we use the electrosensory system of mormyrid weakly electric fish to investigate how a population of neurons with diverse temporal filtering properties encodes behaviorally relevant input timing patterns, and how this relates to behavioral sensitivity. We show that fish are behaviorally sensitive to millisecond variations in natural, temporally patterned communication signals, and that the responses of individual midbrain neurons are also sensitive to variation in these patterns. In fact, the output of single neurons contains enough information to discriminate stereotyped communication signals produced by different individuals. PMID:27559179

Behavioral and Single-Neuron Sensitivity to Millisecond Variations in Temporally Patterned Communication Signals.

PubMed

Baker, Christa A; Ma, Lisa; Casareale, Chelsea R; Carlson, Bruce A

2016-08-24

In many sensory pathways, central neurons serve as temporal filters for timing patterns in communication signals. However, how a population of neurons with diverse temporal filtering properties codes for natural variation in communication signals is unknown. Here we addressed this question in the weakly electric fish Brienomyrus brachyistius, which varies the time intervals between successive electric organ discharges to communicate. These fish produce an individually stereotyped signal called a scallop, which consists of a distinctive temporal pattern of ∼8-12 electric pulses. We manipulated the temporal structure of natural scallops during behavioral playback and in vivo electrophysiology experiments to probe the temporal sensitivity of scallop encoding and recognition. We found that presenting time-reversed, randomized, or jittered scallops increased behavioral response thresholds, demonstrating that fish's electric signaling behavior was sensitive to the precise temporal structure of scallops. Next, using in vivo intracellular recordings and discriminant function analysis, we found that the responses of interval-selective midbrain neurons were also sensitive to the precise temporal structure of scallops. Subthreshold changes in membrane potential recorded from single neurons discriminated natural scallops from time-reversed, randomized, and jittered sequences. Pooling the responses of multiple neurons improved the discriminability of natural sequences from temporally manipulated sequences. Finally, we found that single-neuron responses were sensitive to interindividual variation in scallop sequences, raising the question of whether fish may analyze scallop structure to gain information about the sender. Collectively, these results demonstrate that a population of interval-selective neurons can encode behaviorally relevant temporal patterns with millisecond precision. The timing patterns of action potentials, or spikes, play important roles in representing information in the nervous system. However, how these temporal patterns are recognized by downstream neurons is not well understood. Here we use the electrosensory system of mormyrid weakly electric fish to investigate how a population of neurons with diverse temporal filtering properties encodes behaviorally relevant input timing patterns, and how this relates to behavioral sensitivity. We show that fish are behaviorally sensitive to millisecond variations in natural, temporally patterned communication signals, and that the responses of individual midbrain neurons are also sensitive to variation in these patterns. In fact, the output of single neurons contains enough information to discriminate stereotyped communication signals produced by different individuals. Copyright © 2016 the authors 0270-6474/16/368985-16$15.00/0.

Biogeographical Interpretation of Elevational Patterns of Genus Diversity of Seed Plants in Nepal

PubMed Central

Li, Miao; Feng, Jianmeng

2015-01-01

This study tests if the biogeographical affinities of genera are relevant for explaining elevational plant diversity patterns in Nepal. We used simultaneous autoregressive (SAR) models to investigate the explanatory power of several predictors in explaining the diversity-elevation relationships shown in genera with different biogeographical affinities. Delta akaike information criterion (ΔAIC) was used for multi-model inferences and selections. Our results showed that both the total and tropical genus diversity peaked below the mid-point of the elevational gradient, whereas that of temperate genera had a nearly symmetrical, unimodal relationship with elevation. The proportion of temperate genera increased markedly with elevation, while that of tropical genera declined. Compared to tropical genera, temperate genera had wider elevational ranges and were observed at higher elevations. Water-related variables, rather than mid-domain effects (MDE), were the most significant predictors of elevational patterns of tropical genus diversity. The temperate genus diversity was influenced by energy availability, but only in quadratic terms of the models. Though climatic factors and mid-domain effects jointly explained most of the variation in the diversity of temperate genera with elevation, the former played stronger roles. Total genus diversity was most strongly influenced by climate and the floristic overlap of tropical and temperate floras, while the influences of mid-domain effects were relatively weak. The influences of water-related and energy-related variables may vary with biogeographical affinities. The elevational patterns may be most closely related to climatic factors, while MDE may somewhat modify the patterns. Caution is needed when investigating the causal factors underlying diversity patterns for large taxonomic groups composed of taxa of different biogeographical affinities. Right-skewed diversity-elevation patterns may be produced by the differential response of taxa with varying biogeographical affinities to climatic factors and MDE. PMID:26488164

Biogeographical Interpretation of Elevational Patterns of Genus Diversity of Seed Plants in Nepal.

PubMed

Li, Miao; Feng, Jianmeng

2015-01-01

This study tests if the biogeographical affinities of genera are relevant for explaining elevational plant diversity patterns in Nepal. We used simultaneous autoregressive (SAR) models to investigate the explanatory power of several predictors in explaining the diversity-elevation relationships shown in genera with different biogeographical affinities. Delta akaike information criterion (ΔAIC) was used for multi-model inferences and selections. Our results showed that both the total and tropical genus diversity peaked below the mid-point of the elevational gradient, whereas that of temperate genera had a nearly symmetrical, unimodal relationship with elevation. The proportion of temperate genera increased markedly with elevation, while that of tropical genera declined. Compared to tropical genera, temperate genera had wider elevational ranges and were observed at higher elevations. Water-related variables, rather than mid-domain effects (MDE), were the most significant predictors of elevational patterns of tropical genus diversity. The temperate genus diversity was influenced by energy availability, but only in quadratic terms of the models. Though climatic factors and mid-domain effects jointly explained most of the variation in the diversity of temperate genera with elevation, the former played stronger roles. Total genus diversity was most strongly influenced by climate and the floristic overlap of tropical and temperate floras, while the influences of mid-domain effects were relatively weak. The influences of water-related and energy-related variables may vary with biogeographical affinities. The elevational patterns may be most closely related to climatic factors, while MDE may somewhat modify the patterns. Caution is needed when investigating the causal factors underlying diversity patterns for large taxonomic groups composed of taxa of different biogeographical affinities. Right-skewed diversity-elevation patterns may be produced by the differential response of taxa with varying biogeographical affinities to climatic factors and MDE.

Modulation of heart rate response to acute stressors throughout the breeding season in the king penguin Aptenodytes patagonicus.

PubMed

Viblanc, Vincent A; Smith, Andrew D; Gineste, Benoit; Kauffmann, Marion; Groscolas, René

2015-06-01

'Fight-or-flight' stress responses allow animals to cope adaptively to sudden threats by mobilizing energy resources and priming the body for action. Because such responses can be costly and redirect behavior and energy from reproduction to survival, they are likely to be shaped by specific life-history stages, depending on the available energy resources and the commitment to reproduction. Here, we consider how heart rate (HR) responses to acute stressors are affected by the advancing breeding season in a colonial seabird, the king penguin (Aptenodytes patagonicus). We subjected 77 birds (44 males, 33 females) at various stages of incubation and chick-rearing to three experimental stressors (metal sound, distant approach and capture) known to vary both in their intensity and associated risk, and monitored their HR responses. Our results show that HR increase in response to acute stressors was progressively attenuated with the stage of breeding from incubation to chick-rearing. Stress responses did not vary according to nutritional status or seasonal timing (whether breeding was initiated early or late in the season), but were markedly lower during chick-rearing than during incubation. This pattern was obvious for all three stressors. We discuss how 'fight-or-flight' responses may be modulated by considering the energy commitment to breeding, nutritional status and reproductive value of the brood in breeding seabirds. © 2015. Published by The Company of Biologists Ltd.

Ecohydrological responses of a model semiarid system to precipitation pulses after a global change type dry-down depend on growth-form, event size, and time since establishment

NASA Astrophysics Data System (ADS)

Barron-Gafford, G. A.; Minor, R. L.; Braun, Z.; Potts, D. L.

2012-12-01

Woody encroachment into grasslands alters ecosystem structure and function both above- and belowground. Aboveground, woody plant canopies increase leaf area index and alter patterns of interception, infiltration and runoff. Belowground, woody plants alter root distribution and increase maximum rooting depth with the effect of accessing deeper pools of soil moisture and shifting the timing and duration of evapotranspiration. In turn, these woody plants mediate hydrological changes that influence patterns of ecosystem CO2 exchange and productivity. Given projections of more variable precipitation and increased temperatures for many semiarid regions, differences in physiological performance are likely to drive changes in ecosystem-scale carbon and water flux depending on the degree of woody cover. Ultimately, as soil moisture declines with decreased precipitation, differential patterns of environmental sensitivity among growth-forms and their dependence on groundwater will only become more important in determining ecosystem resilience to future change. Here, we created a series of 1-meter deep mesocosms that housed either a woody mesquite shrub, a bunchgrass, or was left as bare soil. Five replicates of each were maintained under current ambient air temperatures, and five replicates were maintained under projected (+4oC) air temperatures. Each mesocosm was outfitted with an array of soil moisture, temperature, water potential, and CO2 exchange concentration sensors at the near-surface, 30, 55, and 80cm depths to quantify patterns of soil moisture and respiratory CO2 exchange efflux in response to rainfall events of varying magnitude and intervening dry periods of varying duration. In addition, we used minirhizotrons to quantify the response of roots to episodic rainfall. During the first year, bunchgrasses photosynthetically outperformed mesquite saplings across a wider range of temperatures under dry conditions, regardless of growth temperature (ambient or +4oC). Both growth forms were similarly responsive to episodic rainfall, regardless of event magnitude, though mesquite were able to maintain photosynthetic function for a longer period in response to each rain. However, in the second year of the experiment a new pattern of response to moisture and high temperature stress emerged. Under dry conditions, mesquite sustained high photosynthetic rates across a wider range of atmospheric temperatures and were less responsive to rainfall, regardless of event magnitude. In contrast, the limiting effect of high temperatures on bunchgrass photosynthesis was soil moisture dependent. In this case, the effects of high temperature limitation were exaggerated under dry conditions and relaxed when soil moisture was more abundant. Together, these trends yielded a significantly greater photosynthetic assimilation by deeper-rooted mesquite shrubs than shallow-rooted bunchgrasses under both temperature regimes. Combining these aboveground measurements of carbon uptake with belowground estimates of carbon efflux will allow us to make much more informed projections of net carbon balance within mixed vegetation shrublands across a range of global climate change projections.

Pattern recognition receptor-mediated cytokine response in infants across 4 continents.

PubMed

Smolen, Kinga K; Ruck, Candice E; Fortuno, Edgardo S; Ho, Kevin; Dimitriu, Pedro; Mohn, William W; Speert, David P; Cooper, Philip J; Esser, Monika; Goetghebuer, Tessa; Marchant, Arnaud; Kollmann, Tobias R

2014-03-01

Susceptibility to infection as well as response to vaccination varies among populations. To date, the underlying mechanisms responsible for these clinical observations have not been fully delineated. Because innate immunity instructs adaptive immunity, we hypothesized that differences between populations in innate immune responses may represent a mechanistic link to variation in susceptibility to infection or response to vaccination. Determine whether differences in innate immune responses exist among infants from different continents of the world. We determined the innate cytokine response following pattern recognition receptor (PRR) stimulation of whole blood from 2-year-old infants across 4 continents (Africa, North America, South America, and Europe). We found that despite the many possible genetic and environmental exposure differences in infants across 4 continents, innate cytokine responses were similar for infants from North America, South America, and Europe. However, cells from South African infants secreted significantly lower levels of cytokines than did cells from infants from the 3 other sites, and did so following stimulation of extracellular and endosomal but not cytosolic PRRs. Substantial differences in innate cytokine responses to PRR stimulation exist among different populations of infants that could not have been predicted. Delineating the underlying mechanism(s) for these differences will not only aid in improving vaccine-mediated protection but possibly also provide clues for the susceptibility to infection in different regions of the world. Copyright © 2013 The Authors. Published by Mosby, Inc. All rights reserved.

Fast electron microscopy via compressive sensing

DOEpatents

Larson, Kurt W; Anderson, Hyrum S; Wheeler, Jason W

2014-12-09

Various technologies described herein pertain to compressive sensing electron microscopy. A compressive sensing electron microscope includes a multi-beam generator and a detector. The multi-beam generator emits a sequence of electron patterns over time. Each of the electron patterns can include a plurality of electron beams, where the plurality of electron beams is configured to impart a spatially varying electron density on a sample. Further, the spatially varying electron density varies between each of the electron patterns in the sequence. Moreover, the detector collects signals respectively corresponding to interactions between the sample and each of the electron patterns in the sequence.

Fractal analysis of time varying data

DOEpatents

Vo-Dinh, Tuan; Sadana, Ajit

2002-01-01

Characteristics of time varying data, such as an electrical signal, are analyzed by converting the data from a temporal domain into a spatial domain pattern. Fractal analysis is performed on the spatial domain pattern, thereby producing a fractal dimension D.sub.F. The fractal dimension indicates the regularity of the time varying data.

Understanding the varied response of the extratropical storm tracks to climate change

PubMed Central

O’Gorman, Paul A.

2010-01-01

Transient eddies in the extratropical storm tracks are a primary mechanism for the transport of momentum, energy, and water in the atmosphere, and as such are a major component of the climate system. Changes in the extratropical storm tracks under global warming would impact these transports, the ocean circulation and carbon cycle, and society through changing weather patterns. I show that the southern storm track intensifies in the multimodel mean of simulations of 21st century climate change, and that the seasonal cycle of storm-track intensity increases in amplitude in both hemispheres. I use observations of the present-day seasonal cycle to confirm the relationship between storm-track intensity and the mean available potential energy of the atmosphere, and show how this quantitative relationship can be used to account for much of the varied response in storm-track intensity to global warming, including substantially different responses in simulations with different climate models. The results suggest that storm-track intensity is not related in a simple way to global-mean surface temperature, so that, for example, a stronger southern storm track in response to present-day global warming does not imply it was also stronger in hothouse climates of the past. PMID:20974916

Understanding the varied response of the extratropical storm tracks to climate change.

PubMed

O'Gorman, Paul A

2010-11-09

Transient eddies in the extratropical storm tracks are a primary mechanism for the transport of momentum, energy, and water in the atmosphere, and as such are a major component of the climate system. Changes in the extratropical storm tracks under global warming would impact these transports, the ocean circulation and carbon cycle, and society through changing weather patterns. I show that the southern storm track intensifies in the multimodel mean of simulations of 21st century climate change, and that the seasonal cycle of storm-track intensity increases in amplitude in both hemispheres. I use observations of the present-day seasonal cycle to confirm the relationship between storm-track intensity and the mean available potential energy of the atmosphere, and show how this quantitative relationship can be used to account for much of the varied response in storm-track intensity to global warming, including substantially different responses in simulations with different climate models. The results suggest that storm-track intensity is not related in a simple way to global-mean surface temperature, so that, for example, a stronger southern storm track in response to present-day global warming does not imply it was also stronger in hothouse climates of the past.

Ingroup favoritism or the black sheep effect: Perceived intentions modulate subjective responses to aggressive interactions.

PubMed

Wang, Lei; Zheng, Jiehui; Meng, Liang; Lu, Qiang; Ma, Qingguo

2016-07-01

Social categorization plays an important role in provoking the victim's responses to aggressive interactions. Pioneering studies suggested that uncertainty in the perpetrator's hostile intention influences whether ingroup favoritism or the black sheep effect (ingroup strictness) will be manifested to a greater extent. However, when the hostile intention is ambiguous, subjective perception of the perpetrator's intention may still be quite different due to the inherent information gap between participants, and this discrepancy in perceived intentions may further modulate subjective responses to social aggression. In the present study, subjects played as responders of the Ultimatum Game, and received varied offers proposed by either ingroup or outgroup members. Electrophysiological results showed that, when proposers were perceived to be intentional, unfair offers from ingroups elicited significantly larger Feedback-related Negativity (FRN) than those from outgroups, potentially providing neural evidence for the black sheep effect. The opposite FRN pattern was observed when proposers were perceived to be unintentional, which might suggest ingroup favoritism. Interestingly, despite contrary neural patterns, perceived intentions did not modulate behavioral response to aggressive interactions. Thus, converging results suggested that, when the perpetrator's hostile intention remained ambiguous, perceived intentions modulated the victim's electrophysiological response while not the rational behavioral response to aggressive interactions. Copyright © 2016 Elsevier Ireland Ltd and Japan Neuroscience Society. All rights reserved.

The Effects of Gender and Relationship Context Cues on Responsive Sexual Desire in Exclusively and Predominantly Androphilic Women and Gynephilic Men.

PubMed

Timmers, Amanda D; Dawson, Samantha J; Chivers, Meredith L

2018-04-20

Sexual desire may be "responsive," emerging from sexual arousal to sexually competent cues. Cues that elicit sexual arousal and desire differ, however, by gender and direction of sexual attractions. Further, relationship context cues are thought to be important for responsive desire, but this has not been tested directly. The current study examined gynephilic men's (n = 27) and exclusively (n = 23) and predominantly (n = 17) androphilic women's dyadic and solitary responsive sexual desire, as well as genital and self-reported arousal, to audio narratives varying by gender (male, female) of the sexual partner and relationship context (stranger, friend, long-term relationship). Consistent with previous literature, gynephilic men's solitary and dyadic desire were gender-specific (greater to female than to male sexual partners). Exclusively androphilic women's dyadic desire differentiated less to cues of gender than gynephilic men's, and their solitary desire did not differentiate by gender cues at all, replicating previous research. Androphilic women with some gynephilia reported a gender-nonspecific pattern of dyadic and solitary desire (i.e., responsive desire to both male and female narratives). No effect of relationship context was found for any groups. Results suggest that responsive sexual desire may be more closely associated with self-reported than genital arousal patterns.

Association Between Inflammatory Diet Pattern and Risk of Colorectal Carcinoma Subtypes Classified by Immune Responses to Tumor.

PubMed

Liu, Li; Nishihara, Reiko; Qian, Zhi Rong; Tabung, Fred K; Nevo, Daniel; Zhang, Xuehong; Song, Mingyang; Cao, Yin; Mima, Kosuke; Masugi, Yohei; Shi, Yan; da Silva, Annacarolina; Twombly, Tyler; Gu, Mancang; Li, Wanwan; Hamada, Tsuyoshi; Kosumi, Keisuke; Inamura, Kentaro; Nowak, Jonathan A; Drew, David A; Lochhead, Paul; Nosho, Katsuhiko; Wu, Kana; Wang, Molin; Garrett, Wendy S; Chan, Andrew T; Fuchs, Charles S; Giovannucci, Edward L; Ogino, Shuji

2017-12-01

Dietary patterns affect systemic and local intestinal inflammation, which have been linked to colorectal carcinogenesis. Chronic inflammation can interfere with the adaptive immune response. We investigated whether the association of a diet that promotes intestinal inflammation with risk of colorectal carcinoma was stronger for tumors with lower lymphocytic reactions than tumors with higher lymphocytic reactions. We collected data from the molecular pathological epidemiology databases of 2 prospective cohort studies: the Nurses' Health Study (since 1976) and the Health Professionals Follow-Up Study (since 1986). We used duplication-method time-varying Cox proportional cause-specific hazards regression to assess the association of empirical dietary inflammatory pattern (EDIP) score (derived from food frequency questionnaire data) with colorectal carcinoma subtype. Foods that contribute to high EDIP scores include red and processed meats, refined grains, carbonated beverages, and some vegetables; foods that contribute to low EDIP scores include beer, wine, coffee, tea, yellow and leafy vegetables, and fruit juice. Colorectal tissue samples were analyzed histologically for patterns of lymphocytic reactions (Crohn's-like lymphoid reaction, peritumoral lymphocytic reaction, intratumoral periglandular reaction, and tumor-infiltrating lymphocytes). During follow-up of 124,433 participants, we documented 1311 incident colon and rectal cancer cases with available tissue data. The association between the EDIP and colorectal cancer risk was significant (P trend  = .02), and varied with degree of peritumoral lymphocytic reaction (P heterogeneity < .001). Higher EDIP scores were associated with increased risk of colorectal cancer with an absent or low peritumoral lymphocytic reaction (highest vs lowest EDIP score quintile hazard ratio, 2.60; 95% confidence interval, 1.60-4.23; P trend < .001), but not risk of tumors with intermediate or high peritumoral lymphocytic reaction (P trend > .80). In 2 prospective cohort studies, we associated inflammatory diets with a higher risk of colorectal cancer subtype that contains little or no peritumoral lymphocytic reaction. These findings suggest that diet-related inflammation might contribute to development of colorectal cancer, by suppressing the adaptive anti-tumor immune response. Copyright © 2017 AGA Institute. Published by Elsevier Inc. All rights reserved.

Across species-pool aggregation alters grassland productivity and diversity.

PubMed

McKenna, Thomas P; Yurkonis, Kathryn A

2016-08-01

Plant performance is determined by the balance of intra- and interspecific neighbors within an individual's zone of influence. If individuals interact over smaller scales than the scales at which communities are measured, then altering neighborhood interactions may fundamentally affect community responses. These interactions can be altered by changing the number (species richness), abundances (species evenness), and positions (species pattern) of the resident plant species, and we aimed to test whether aggregating species at planting would alter effects of species richness and evenness on biomass production at a common scale of observation in grasslands. We varied plant species richness (2, 4, or 8 species and monocultures), evenness (0.64, 0.8, or 1.0), and pattern (planted randomly or aggregated in groups of four individuals) within 1 × 1 m plots established with transplants from a pool of 16 tallgrass prairie species and assessed plot-scale biomass production and diversity over the first three growing seasons. As expected, more species-rich plots produced more biomass by the end of the third growing season, an effect associated with a shift from selection to complementarity effects over time. Aggregating conspecifics at a 0.25-m scale marginally reduced biomass production across all treatments and increased diversity in the most even plots, but did not alter biodiversity effects or richness-productivity relationships. Results support the hypothesis that fine-scale species aggregation affects diversity by promoting species coexistence in this system. However, results indicate that inherent changes in species neighborhood relationships along grassland diversity gradients may only minimally affect community (meter) - scale responses among similarly designed biodiversity-ecosystem function studies. Given that species varied in their responses to local aggregation, it may be possible to use such species-specific results to spatially design larger-scale grassland communities to achieve desired diversity and productivity responses.

A Complex Story: Universal Preference vs. Individual Differences Shaping Aesthetic Response to Fractals Patterns.

PubMed

Street, Nichola; Forsythe, Alexandra M; Reilly, Ronan; Taylor, Richard; Helmy, Mai S

2016-01-01

Fractal patterns offer one way to represent the rough complexity of the natural world. Whilst they dominate many of our visual experiences in nature, little large-scale perceptual research has been done to explore how we respond aesthetically to these patterns. Previous research (Taylor et al., 2011) suggests that the fractal patterns with mid-range fractal dimensions (FDs) have universal aesthetic appeal. Perceptual and aesthetic responses to visual complexity have been more varied with findings suggesting both linear (Forsythe et al., 2011) and curvilinear (Berlyne, 1970) relationships. Individual differences have been found to account for many of the differences we see in aesthetic responses but some, such as culture, have received little attention within the fractal and complexity research fields. This two-study article aims to test preference responses to FD and visual complexity, using a large cohort (N = 443) of participants from around the world to allow universality claims to be tested. It explores the extent to which age, culture and gender can predict our preferences for fractally complex patterns. Following exploratory analysis that found strong correlations between FD and visual complexity, a series of linear mixed-effect models were implemented to explore if each of the individual variables could predict preference. The first tested a linear complexity model (likelihood of selecting the more complex image from the pair of images) and the second a mid-range FD model (likelihood of selecting an image within mid-range). Results show that individual differences can reliably predict preferences for complexity across culture, gender and age. However, in fitting with current findings the mid-range models show greater consistency in preference not mediated by gender, age or culture. This article supports the established theory that the mid-range fractal patterns appear to be a universal construct underlying preference but also highlights the fragility of universal claims by demonstrating individual differences in preference for the interrelated concept of visual complexity. This highlights a current stalemate in the field of empirical aesthetics.

Delayed Response and Biosonar Perception Explain Movement Coordination in Trawling Bats

PubMed Central

Giuggioli, Luca; McKetterick, Thomas J.; Holderied, Marc

2015-01-01

Animal coordinated movement interactions are commonly explained by assuming unspecified social forces of attraction, repulsion and alignment with parameters drawn from observed movement data. Here we propose and test a biologically realistic and quantifiable biosonar movement interaction mechanism for echolocating bats based on spatial perceptual bias, i.e. actual sound field, a reaction delay, and observed motor constraints in speed and acceleration. We found that foraging pairs of bats flying over a water surface swapped leader-follower roles and performed chases or coordinated manoeuvres by copying the heading a nearby individual has had up to 500 ms earlier. Our proposed mechanism based on the interplay between sensory-motor constraints and delayed alignment was able to recreate the observed spatial actor-reactor patterns. Remarkably, when we varied model parameters (response delay, hearing threshold and echolocation directionality) beyond those observed in nature, the spatio-temporal interaction patterns created by the model only recreated the observed interactions, i.e. chases, and best matched the observed spatial patterns for just those response delays, hearing thresholds and echolocation directionalities found to be used by bats. This supports the validity of our sensory ecology approach of movement coordination, where interacting bats localise each other by active echolocation rather than eavesdropping. PMID:25811627

Selective attention to temporal features on nested time scales.

PubMed

Henry, Molly J; Herrmann, Björn; Obleser, Jonas

2015-02-01

Meaningful auditory stimuli such as speech and music often vary simultaneously along multiple time scales. Thus, listeners must selectively attend to, and selectively ignore, separate but intertwined temporal features. The current study aimed to identify and characterize the neural network specifically involved in this feature-selective attention to time. We used a novel paradigm where listeners judged either the duration or modulation rate of auditory stimuli, and in which the stimulation, working memory demands, response requirements, and task difficulty were held constant. A first analysis identified all brain regions where individual brain activation patterns were correlated with individual behavioral performance patterns, which thus supported temporal judgments generically. A second analysis then isolated those brain regions that specifically regulated selective attention to temporal features: Neural responses in a bilateral fronto-parietal network including insular cortex and basal ganglia decreased with degree of change of the attended temporal feature. Critically, response patterns in these regions were inverted when the task required selectively ignoring this feature. The results demonstrate how the neural analysis of complex acoustic stimuli with multiple temporal features depends on a fronto-parietal network that simultaneously regulates the selective gain for attended and ignored temporal features. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Epigenetic dysregulation of the dopamine system in diet-induced obesity.

PubMed

Vucetic, Zivjena; Carlin, Jesse Lea; Totoki, Kathy; Reyes, Teresa M

2012-03-01

Chronic intake of high-fat (HF) diet is known to alter brain neurotransmitter systems that participate in the central regulation of food intake. Dopamine (DA) system changes in response to HF diet have been observed in the hypothalamus, important in the homeostatic control of food intake, as well as within the central reward circuitry [ventral tegmental area (VTA), nucleus accumbens (NAc), and pre-frontal cortex (PFC)], critical for coding the rewarding properties of palatable food and important in hedonically driven feeding behavior. Using a mouse model of diet-induced obesity (DIO), significant alterations in the expression of DA-related genes were documented in adult animals, and the general pattern of gene expression changes was opposite within the hypothalamus versus the reward circuitry (increased vs. decreased, respectively). Differential DNA methylation was identified within the promoter regions of tyrosine hydroxylase (TH) and dopamine transporter (DAT), and the pattern of this response was consistent with the pattern of gene expression. Behaviors consistent with increased hypothalamic DA and decreased reward circuitry DA were observed. These data identify differential DNA methylation as an epigenetic mechanism linking the chronic intake of HF diet with altered DA-related gene expression, and this response varies by brain region and DNA sequence. © 2012 The Authors. Journal of Neurochemistry © 2012 International Society for Neurochemistry.

Secretion of Galectin-9 as a DAMP during Dengue Virus Infection in THP-1 Cells.

PubMed

Dapat, Isolde C; Pascapurnama, Dyshelly Nurkartika; Iwasaki, Hiroko; Labayo, Hannah Karen; Chagan-Yasutan, Haorile; Egawa, Shinichi; Hattori, Toshio

2017-07-28

Damage-associated molecular patterns (DAMPs) are endogenous cellular molecules released to the extracellular environment in response to stress conditions such as virus infection. Galectins are β-galactoside-binding proteins that are widely expressed in cells and tissues of the immune system, are localized in the cell cytoplasm, and have roles in inflammatory responses and immune responses against infection. Elevated levels of galectin-9 (Gal-9) in natural human infections have been documented in numerous reports. To investigate the effect of dengue virus (DENV) infection on expression of endogenous Gal-9, monocytic THP-1 cells were infected with varying doses of DENV-3 (multiplicity of infection (MOI) 0.01, 0.03 and 0.1) and incubated at varying time points (Day 1, Day 2, Day 3). Results showed augmentation of Gal-9 levels in the supernatant, reduction of Gal-9 levels in the cells and decreased expression of LGALS9 mRNA, while DENV-3 mRNA copies for all three doses remained stable through time. Dengue virus induced the secretion of Gal-9 as a danger response; in turn, Gal-9 and other inflammatory factors, and stimulated effector responses may have limited further viral replication. The results in this pilot experiment add to the evidence of Gal-9 as a potential DAMP.

Impact of genetic risk information and type of disease on perceived risk, anticipated affect, and expected consequences of genetic tests.

PubMed

Cameron, Linda D; Sherman, Kerry A; Marteau, Theresa M; Brown, Paul M

2009-05-01

Genetic tests vary in their prediction of disease occurrence, with some mutations conferring relatively low risk and others indicating near certainty. The authors assessed how increments in absolute risk of disease influence risk perceptions, interest, and expected consequences of genetic tests for diseases of varying severity. Adults (N = 752), recruited from New Zealand, Australia, and the United Kingdom for an online analogue study, were randomly assigned to receive information about a test of genetic risk for diabetes, heart disease, colon cancer, or lung cancer. The lifetime risk varied across conditions by 10% increments, from 20% to 100%. Participants completed measures of perceived likelihood of disease for individuals with mutations, risk-related affect, interest, and testing consequences. Analyses revealed two increment clusters yielding differences in likelihood perceptions: A "moderate-risk" cluster (20%-70%), and a "high-risk" cluster (80%-100%). Risk increment influenced anticipated worry, feelings of risk, testing-induced distress, and family obligations, with nonlinear patterns including disproportionately high responses for the 50% increment. Risk increment did not alter testing interest or perceived benefits. These patterns of effects held across the four diseases. Magnitude of risk from genetic testing has a nonlinear influence on risk-related appraisals and affect but is unrelated to test interest.

Investigation of relative risk estimates from studies of the same population with contrasting response rates and designs.

PubMed

Mealing, Nicole M; Banks, Emily; Jorm, Louisa R; Steel, David G; Clements, Mark S; Rogers, Kris D

2010-04-01

There is little empirical evidence regarding the generalisability of relative risk estimates from studies which have relatively low response rates or are of limited representativeness. The aim of this study was to investigate variation in exposure-outcome relationships in studies of the same population with different response rates and designs by comparing estimates from the 45 and Up Study, a population-based cohort study (self-administered postal questionnaire, response rate 18%), and the New South Wales Population Health Survey (PHS) (computer-assisted telephone interview, response rate ~60%). Logistic regression analysis of questionnaire data from 45 and Up Study participants (n = 101,812) and 2006/2007 PHS participants (n = 14,796) was used to calculate prevalence estimates and odds ratios (ORs) for comparable variables, adjusting for age, sex and remoteness. ORs were compared using Wald tests modelling each study separately, with and without sampling weights. Prevalence of some outcomes (smoking, private health insurance, diabetes, hypertension, asthma) varied between the two studies. For highly comparable questionnaire items, exposure-outcome relationship patterns were almost identical between the studies and ORs for eight of the ten relationships examined did not differ significantly. For questionnaire items that were only moderately comparable, the nature of the observed relationships did not differ materially between the two studies, although many ORs differed significantly. These findings show that for a broad range of risk factors, two studies of the same population with varying response rate, sampling frame and mode of questionnaire administration yielded consistent estimates of exposure-outcome relationships. However, ORs varied between the studies where they did not use identical questionnaire items.

Changes in frontal plane dynamics and the loading response phase of the gait cycle are characteristic of severe knee osteoarthritis application of a multidimensional analysis technique.

PubMed

Astephen, J L; Deluzio, K J

2005-02-01

Osteoarthritis of the knee is related to many correlated mechanical factors that can be measured with gait analysis. Gait analysis results in large data sets. The analysis of these data is difficult due to the correlated, multidimensional nature of the measures. A multidimensional model that uses two multivariate statistical techniques, principal component analysis and discriminant analysis, was used to discriminate between the gait patterns of the normal subject group and the osteoarthritis subject group. Nine time varying gait measures and eight discrete measures were included in the analysis. All interrelationships between and within the measures were retained in the analysis. The multidimensional analysis technique successfully separated the gait patterns of normal and knee osteoarthritis subjects with a misclassification error rate of <6%. The most discriminatory feature described a static and dynamic alignment factor. The second most discriminatory feature described a gait pattern change during the loading response phase of the gait cycle. The interrelationships between gait measures and between the time instants of the gait cycle can provide insight into the mechanical mechanisms of pathologies such as knee osteoarthritis. These results suggest that changes in frontal plane loading and alignment and the loading response phase of the gait cycle are characteristic of severe knee osteoarthritis gait patterns. Subsequent investigations earlier in the disease process may suggest the importance of these factors to the progression of knee osteoarthritis.

Classification of Thermal Patterns at Karst Springs and Cave Streams

USGS Publications Warehouse

Luhmann, A.J.; Covington, M.D.; Peters, Albert J.; Alexander, S.C.; Anger, C.T.; Green, J.A.; Runkel, Anthony C.; Alexander, E.C.

2011-01-01

Thermal patterns of karst springs and cave streams provide potentially useful information concerning aquifer geometry and recharge. Temperature monitoring at 25 springs and cave streams in southeastern Minnesota has shown four distinct thermal patterns. These patterns can be divided into two types: those produced by flow paths with ineffective heat exchange, such as conduits, and those produced by flow paths with effective heat exchange, such as small fractures and pore space. Thermally ineffective patterns result when water flows through the aquifer before it can equilibrate to the rock temperature. Thermally ineffective patterns can be either event-scale, as produced by rainfall or snowmelt events, or seasonal scale, as produced by input from a perennial surface stream. Thermally effective patterns result when water equilibrates to rock temperature, and the patterns displayed depend on whether the aquifer temperature is changing over time. Shallow aquifers with seasonally varying temperatures display a phase-shifted seasonal signal, whereas deeper aquifers with constant temperatures display a stable temperature pattern. An individual aquifer may display more than one of these patterns. Since karst aquifers typically contain both thermally effective and ineffective routes, we argue that the thermal response is strongly influenced by recharge mode. ?? 2010 The Author(s). Journal compilation ?? 2010 National Ground Water Association.

Multivariate analysis of correlation between electrophysiological and hemodynamic responses during cognitive processing

PubMed Central

Kujala, Jan; Sudre, Gustavo; Vartiainen, Johanna; Liljeström, Mia; Mitchell, Tom; Salmelin, Riitta

2014-01-01

Animal and human studies have frequently shown that in primary sensory and motor regions the BOLD signal correlates positively with high-frequency and negatively with low-frequency neuronal activity. However, recent evidence suggests that this relationship may also vary across cortical areas. Detailed knowledge of the possible spectral diversity between electrophysiological and hemodynamic responses across the human cortex would be essential for neural-level interpretation of fMRI data and for informative multimodal combination of electromagnetic and hemodynamic imaging data, especially in cognitive tasks. We applied multivariate partial least squares correlation analysis to MEG–fMRI data recorded in a reading paradigm to determine the correlation patterns between the data types, at once, across the cortex. Our results revealed heterogeneous patterns of high-frequency correlation between MEG and fMRI responses, with marked dissociation between lower and higher order cortical regions. The low-frequency range showed substantial variance, with negative and positive correlations manifesting at different frequencies across cortical regions. These findings demonstrate the complexity of the neurophysiological counterparts of hemodynamic fluctuations in cognitive processing. PMID:24518260

Using Divertor Strike Point Splitting to Study Plasma Response and Its Sensitivity to Equilibrium Uncertainties

NASA Astrophysics Data System (ADS)

Teklu, Abraham; Orlov, D. M.; Moyer, R. A.; Bykov, I.; Evans, T. E.; Wu, W.; Trevisan, G. L.; Lyons, B. C.; Abrams, T.; Makowski, M. A.; Lasnier, C. S.; Fenstermacher, M. E.

2017-10-01

Resonant magnetic perturbations (RMPs) from 3D coils have been varied to modify the splitting of the divertor strike points in DIII-D. This splitting is imaged in filtered visible and infrared emission from the divertor to determine the particle and heat flux patterns on the target plates. The observed splitting is compared to vacuum and plasma response modeling in discharges where a subset of the RMP coils were ramped to shift the divertor footprints from dominantly n = 3 to n = 2 pattern. These results will be used to determine if the plasma response model can be validated with the measured splitting. We will also study the sensitivity of the modeled splitting to details of the 2D equilibrium. This RMP ramp technique could be used in ITER to spread out the heat flux while avoiding excessive forces on the RMP coils. Work supported by U.S. DOE under the Science Undergraduate Laboratory Internship (SULI) program and DE-FC02-04ER54698, DE-FG02-07ER54917, DE-FG02-05ER54809 and DE-AC52-07NA27344.

Abnormal sympathetic nerve activity in women exposed to cigarette smoke: a potential mechanism to explain increased cardiac risk.

PubMed

Middlekauff, Holly R; Park, Jeanie; Agrawal, Harsh; Gornbein, Jeffrey A

2013-11-15

In women, cardiac deaths attributable to tobacco exposure have reached the same high levels as men. Normally, sympathetic nerve activity (SNA) fluctuates according to the menstrual phase, but in habitual smokers, SNA levels remain constant. Our purpose is to extend these observations to other groups of women exposed to tobacco smoke and to explore potential mechanisms. We hypothesize that women exposed to secondhand smoke, but not former smokers, have nonfluctuating SNA compared with never smokers, and that impaired baroreflex suppression of SNA, and/or heightened central SNA responses, underlie this nonfluctuating SNA. We also hypothesize that female smokers have impaired nocturnal blood pressure dipping, normally mediated by modulation of SNA. In 49 females (19 never, 12 current, 9 former, 9 passive smokers), SNA was recorded (microneurography) during high- and low-hormone ovarian phases at rest, during pharmacological baroreflex testing, and during the cold pressor test (CPT). Twenty-four hour blood pressure (BP) monitoring was performed. Current and passive smokers, but not former smokers, had a nonfluctuating pattern of SNA, unlike never smokers in whom SNA varied with the menstrual phase. Baroreflex control of SNA was significantly blunted in current smokers, independent of menstrual phase. In passive smokers, SNA response to CPT was markedly increased. Nondipping was unexpectedly high in all groups. SNA does not vary during the menstrual cycle in active and passive smokers, unlike never and former smokers. Baroreflex control of SNA is blunted in current smokers, whereas SNA response to CPT is heightened in passive smokers. Smoking cessation is associated with return of the altered SNA pattern to normal.

Stoichiometric patterns in foliar nutrient resorption across multiple scales

USGS Publications Warehouse

Reed, Sasha C.; Townsend, Alan R.; Davidson, Eric A.; Cleveland, Cory C.

2012-01-01

*Nutrient resorption is a fundamental process through which plants withdraw nutrients from leaves before abscission. Nutrient resorption patterns have the potential to reflect gradients in plant nutrient limitation and to affect a suite of terrestrial ecosystem functions. *Here, we used a stoichiometric approach to assess patterns in foliar resorption at a variety of scales, specifically exploring how N : P resorption ratios relate to presumed variation in N and/or P limitation and possible relationships between N : P resorption ratios and soil nutrient availability. *N : P resorption ratios varied significantly at the global scale, increasing with latitude and decreasing with mean annual temperature and precipitation. In general, tropical sites (absolute latitudes < 23°26′) had N : P resorption ratios of < 1, and plants growing on highly weathered tropical soils maintained the lowest N : P resorption ratios. Resorption ratios also varied with forest age along an Amazonian forest regeneration chronosequence and among species in a diverse Costa Rican rain forest. *These results suggest that variations in N : P resorption stoichiometry offer insight into nutrient cycling and limitation at a variety of spatial scales, complementing other metrics of plant nutrient biogeochemistry. The extent to which the stoichiometric flexibility of resorption will help regulate terrestrial responses to global change merits further investigation.

Firing Costs and Flexibility: Evidence from Firms’ Employment Responses to Shocks in India*

PubMed Central

Adhvaryu, Achyuta; Chari, A. V.; Sharma, Siddharth

2013-01-01

A key prediction of dynamic labor demand models is that firing restrictions attenuate firms’ employment responses to economic fluctuations. We provide the first direct test of this prediction using data from India. We exploit the fact that rainfall fluctuations, through their effects on agricultural productivity, generate variation in local demand within districts over time. Consistent with the theory, we find that industrial employment is more sensitive to shocks where labor regulation is less restrictive. Our results are robust to controlling for endogenous firm placement and vary across factory size in a pattern consistent with institutional features of Indian labor law. PMID:24357882

Disturbance impacts on land surface temperature and gross primary productivity in the western United States

NASA Astrophysics Data System (ADS)

Cooper, L. Annie; Ballantyne, Ashley P.; Holden, Zachary A.; Landguth, Erin L.

2017-04-01

Forest disturbances influence forest structure, composition, and function and may impact climate through changes in net radiation or through shifts in carbon exchange. Climate impacts vary depending on environmental variables and disturbance characteristics, yet few studies have investigated disturbance impacts over large, environmentally heterogeneous, regions. We used satellite data to objectively determine the impacts of fire, bark beetles, defoliators, and "unidentified disturbances" (UDs) on land surface temperature (LST) and gross primary productivity (GPP) across the western United States (U.S.). We investigated immediate disturbance impacts, the drivers of those impacts, and long-term postdisturbance LST and GPP recovery patterns. All disturbance types caused LST increases (°C; fire: 3.45 ± 3.02, bark beetles: 0.76 ± 3.04, defoliators: 0.49 ± 3.12, and UD: 0.76 ± 3.03). Fire and insects resulted in GPP declines (%; fire: -25.05 ± 21.67, bark beetles: -2.84 ± 21.06, defoliators: -0.23 ± 15.40), while UDs resulted in slightly enhanced GPP (1.89 ± 24.20%). Disturbance responses also varied between ecoregions. Severity and interannual changes in air temperature were the primary drivers of short-term disturbance responses, and severity also had a strong impact on long-term recovery patterns. These results suggest a potential climate feedback due to disturbance-induced biophysical changes that may strengthen as disturbance regimes shift due to climate change.

Physical retrieval of precipitation water contents from Special Sensor Microwave/Imager (SSM/I) data. Part 1: A cloud ensemble/radiative parameterization for sensor response (report version)

NASA Technical Reports Server (NTRS)

Olson, William S.; Raymond, William H.

1990-01-01

The physical retrieval of geophysical parameters based upon remotely sensed data requires a sensor response model which relates the upwelling radiances that the sensor observes to the parameters to be retrieved. In the retrieval of precipitation water contents from satellite passive microwave observations, the sensor response model has two basic components. First, a description of the radiative transfer of microwaves through a precipitating atmosphere must be considered, because it is necessary to establish the physical relationship between precipitation water content and upwelling microwave brightness temperature. Also the spatial response of the satellite microwave sensor (or antenna pattern) must be included in the description of sensor response, since precipitation and the associated brightness temperature field can vary over a typical microwave sensor resolution footprint. A 'population' of convective cells, as well as stratiform clouds, are simulated using a computationally-efficient multi-cylinder cloud model. Ensembles of clouds selected at random from the population, distributed over a 25 km x 25 km model domain, serve as the basis for radiative transfer calculations of upwelling brightness temperatures at the SSM/I frequencies. Sensor spatial response is treated explicitly by convolving the upwelling brightness temperature by the domain-integrated SSM/I antenna patterns. The sensor response model is utilized in precipitation water content retrievals.

Rocks and Rain: orographic precipitation and the form of mountain ranges

NASA Astrophysics Data System (ADS)

Roe, G. H.; Anders, A. M.; Durran, D. R.; Montgomery, D. R.; Hallet, B.

2005-12-01

In mountainous landscapes patterns of erosion reflect patterns of precipitation that are, in turn, controlled by the orography. Ultimately therefore, the feedbacks between orography and the climate it creates are responsible for the sculpting of mountain ranges. Key questions concerning these interactions are: 1) how robust are patterns of precipitation on geologic time scales? and 2) how do those patterns affect landscape form? Since climate is by definition the statistics of weather, there is tremendous information to be gleaned from how patterns of precipitation vary between different weather events. However up to now sparse measurements and computational limitations have hampered our knowledge of such variations. For the Olympics in Washington State, a characteristic midlatitude mountain range, we report results from a high-resolution, state-of-the-art numerical weather prediction model and a dense network of precipitation gauges. Down to scales around 10 km, the patterns of precipitation are remarkably robust both storm-by-storm and year-to-year, lending confidence that they are indeed persistent on the relevant time scales. Secondly, the consequences of the coupled interactions are presented using a landscape evolution model coupled with a simple model of orographic precipitation that is able to substantially reproduce the observed precipitation patterns.

METHODS FOR CLUSTERING TIME SERIES DATA ACQUIRED FROM MOBILE HEALTH APPS.

PubMed

Tignor, Nicole; Wang, Pei; Genes, Nicholas; Rogers, Linda; Hershman, Steven G; Scott, Erick R; Zweig, Micol; Yvonne Chan, Yu-Feng; Schadt, Eric E

2017-01-01

In our recent Asthma Mobile Health Study (AMHS), thousands of asthma patients across the country contributed medical data through the iPhone Asthma Health App on a daily basis for an extended period of time. The collected data included daily self-reported asthma symptoms, symptom triggers, and real time geographic location information. The AMHS is just one of many studies occurring in the context of now many thousands of mobile health apps aimed at improving wellness and better managing chronic disease conditions, leveraging the passive and active collection of data from mobile, handheld smart devices. The ability to identify patient groups or patterns of symptoms that might predict adverse outcomes such as asthma exacerbations or hospitalizations from these types of large, prospectively collected data sets, would be of significant general interest. However, conventional clustering methods cannot be applied to these types of longitudinally collected data, especially survey data actively collected from app users, given heterogeneous patterns of missing values due to: 1) varying survey response rates among different users, 2) varying survey response rates over time of each user, and 3) non-overlapping periods of enrollment among different users. To handle such complicated missing data structure, we proposed a probability imputation model to infer missing data. We also employed a consensus clustering strategy in tandem with the multiple imputation procedure. Through simulation studies under a range of scenarios reflecting real data conditions, we identified favorable performance of the proposed method over other strategies that impute the missing value through low-rank matrix completion. When applying the proposed new method to study asthma triggers and symptoms collected as part of the AMHS, we identified several patient groups with distinct phenotype patterns. Further validation of the methods described in this paper might be used to identify clinically important patterns in large data sets with complicated missing data structure, improving the ability to use such data sets to identify at-risk populations for potential intervention.

Distinct pattern separation related transfer functions in human CA3/dentate and CA1 revealed using high-resolution fMRI and variable mnemonic similarity

PubMed Central

Lacy, Joyce W.; Yassa, Michael A.; Stark, Shauna M.; Muftuler, L. Tugan; Stark, Craig E.L.

2011-01-01

Producing and maintaining distinct (orthogonal) neural representations for similar events is critical to avoiding interference in long-term memory. Recently, our laboratory provided the first evidence for separation-like signals in the human CA3/dentate. Here, we extended this by parametrically varying the change in input (similarity) while monitoring CA1 and CA3/dentate for separation and completion-like signals using high-resolution fMRI. In the CA1, activity varied in a graded fashion in response to increases in the change in input. In contrast, the CA3/dentate showed a stepwise transfer function that was highly sensitive to small changes in input. PMID:21164173

Building a Progressive-Situational Model of Post-Diagnosis Information Seeking for Parents of Individuals With Down Syndrome

PubMed Central

Gibson, Amelia N.

2016-01-01

This grounded theory study used in-depth, semi-structured interview to examine the information-seeking behaviors of 35 parents of children with Down syndrome. Emergent themes include a progressive pattern of behavior including information overload and avoidance, passive attention, and active information seeking; varying preferences between tacit and explicit information at different stages; and selection of information channels and sources that varied based on personal and situational constraints. Based on the findings, the author proposes a progressive model of health information seeking and a framework for using this model to collect data in practice. The author also discusses the practical and theoretical implications of a responsive, progressive approach to understanding parents’ health information–seeking behavior. PMID:28462351

Frontal brain electrical activity (EEG) and heart rate in response to affective infant-directed (ID) speech in 9-month-old infants.

PubMed

Santesso, Diane L; Schmidt, Louis A; Trainor, Laurel J

2007-10-01

Many studies have shown that infants prefer infant-directed (ID) speech to adult-directed (AD) speech. ID speech functions to aid language learning, obtain and/or maintain an infant's attention, and create emotional communication between the infant and caregiver. We examined psychophysiological responses to ID speech that varied in affective content (i.e., love/comfort, surprise, fear) in a group of typically developing 9-month-old infants. Regional EEG and heart rate were collected continuously during stimulus presentation. We found the pattern of overall frontal EEG power was linearly related to affective intensity of the ID speech, such that EEG power was greatest in response to fear, than surprise than love/comfort; this linear pattern was specific to the frontal region. We also noted that heart rate decelerated to ID speech independent of affective content. As well, infants who were reported by their mothers as temperamentally distressed tended to exhibit greater relative right frontal EEG activity during baseline and in response to affective ID speech, consistent with previous work with visual stimuli and extending it to the auditory modality. Findings are discussed in terms of how increases in frontal EEG power in response to different affective intensity may reflect the cognitive aspects of emotional processing across sensory domains in infancy.

Early group bias in the Faroe Islands: Cultural variation in children's group-based reasoning.

PubMed

Schug, Mariah G; Shusterman, Anna; Barth, Hilary; Patalano, Andrea L

2016-01-01

Recent developmental research demonstrates that group bias emerges early in childhood. However, little is known about the extent to which bias in minimal (i.e., arbitrarily assigned) groups varies with children's environment and experience, and whether such bias is universal across cultures. In this study, the development of group bias was investigated using a minimal groups paradigm with 46 four- to six-year-olds from the Faroe Islands. Children observed in-group and out-group members exhibiting varying degrees of prosocial behaviour (egalitarian or stingy sharing). Children did not prefer their in-group in the pretest, but a pro-in-group and anti-out-group sentiment emerged in both conditions in the posttest. Faroese children's response patterns differ from those of American children [Schug, M. G., Shusterman, A., Barth, H., & Patalano, A. L. (2013). Minimal-group membership influences children's responses to novel experience with group members. Developmental Science, 16(1), 47-55], suggesting that intergroup bias shows cultural variation even in a minimal groups context.

Environmental influence on mussel (Mytilus edulis) growth - A quantile regression approach

NASA Astrophysics Data System (ADS)

Bergström, Per; Lindegarth, Mats

2016-03-01

The need for methods for sustainable management and use of coastal ecosystems has increased in the last century. A key aspect for obtaining ecologically and economically sustainable aquaculture in threatened coastal areas is the requirement of geographic information of growth and potential production capacity. Growth varies over time and space and depends on a complex pattern of interactions between the bivalve and a diverse range of environmental factors (e.g. temperature, salinity, food availability). Understanding these processes and modelling the environmental control of bivalve growth has been central in aquaculture. In contrast to the most conventional modelling techniques, quantile regression can handle cases where not all factors are measured and provide the possibility to estimate the effect at different levels of the response distribution and give therefore a more complete picture of the relationship between environmental factors and biological response. Observation of the relationships between environmental factors and growth of the bivalve Mytilus edulis revealed relationships that varied both among level of growth rate and within the range of environmental variables along the Swedish west coast. The strongest patterns were found for water oxygen concentration level which had a negative effect on growth for all oxygen levels and growth levels. However, these patterns coincided with differences in growth among periods and very little of the remaining variability within periods could be explained indicating that interactive processes masked the importance of the individual variables. By using quantile regression and local regression (LOESS) this study was able to provide valuable information on environmental factors influencing the growth of M. edulis and important insight for the development of ecosystem based management tools of aquaculture activities, its use in mitigation efforts and successful management of human use of coastal areas.

A genetically-based latitudinal cline in the emission of herbivore-induced plant volatile organic compounds.

PubMed

Wason, Elizabeth L; Agrawal, Anurag A; Hunter, Mark D

2013-08-01

The existence of predictable latitudinal variation in plant defense against herbivores remains controversial. A prevailing view holds that higher levels of plant defense evolve at low latitudes compared to high latitudes as an adaptive plant response to higher herbivore pressure on low-latitude plants. To date, this prediction has not been examined with respect to volatile organic compounds (VOCs) that many plants emit, often thus attracting the natural enemies of herbivores. Here, we compared genetically-based constitutive and herbivore-induced aboveground vegetative VOC emissions from plants originating across a gradient of more than 10° of latitude (>1,500 km). We collected headspace VOCs from Asclepias syriaca (common milkweed) originating from 20 populations across its natural range and grown in a common garden near the range center. Feeding by specialist Danaus plexippus (monarch) larvae induced VOCs, and field environmental conditions (temperature, light, and humidity) also influenced emissions. Monarch damage increased plant VOC concentrations and altered VOC blends. We found that genetically-based induced VOC emissions varied with the latitude of plant population origin, although the pattern followed the reverse of that predicted-induced VOC concentration increased with increasing latitude. This pattern appeared to be driven by a greater induction of sesquiterpenoids at higher latitudes. In contrast, constitutive VOC emission did not vary systematically with latitude, and the induction of green leafy volatiles declined with latitude. Our results do not support the prevailing view that plant defense is greater at lower than at higher latitudes. That the pattern holds only for herbivore-induced VOC emission, and not constitutive emission, suggests that latitudinal variation in VOCs is not a simple adaptive response to climatic factors.

A survey of UK practice patterns in the delivery of intravitreal injections.

PubMed

Samia-Aly, Emma; Cassels-Brown, Andrew; Morris, Daniel S; Stancliffe, Rachel; Somner, John E A

2015-07-01

To assess UK practice patterns related to the prescription of antibiotics before, during and after intravitreal injections, the location where injections are carried out and the qualifications of those administering the injections. Every ophthalmology unit featured in the Royal College of Ophthalmologists (UK) training directory was contacted. A healthcare professional involved in giving intravitreal injections at each institution completed a questionnaire regarding local practice patterns. A response rate of 85% (115/136) was achieved. Seventy four percent of hospitals (85/115) gave take home antibiotics post intravitreal injection. Twenty three percent (26/115) of hospitals employed non-medical healthcare professionals to administer injections and 83% (96/115) administered intravitreal injections in a dedicated clean room as opposed to an operating theatre. Practice patterns for intravitreal injection vary considerably. Guidelines alone do not appear to be effective in reducing practices which are considered wasteful and other approaches need to be developed. © 2015 The Authors Ophthalmic & Physiological Optics © 2015 The College of Optometrists.

Dynamical state of the network determines the efficacy of single neuron properties in shaping the network activity

PubMed Central

Sahasranamam, Ajith; Vlachos, Ioannis; Aertsen, Ad; Kumar, Arvind

2016-01-01

Spike patterns are among the most common electrophysiological descriptors of neuron types. Surprisingly, it is not clear how the diversity in firing patterns of the neurons in a network affects its activity dynamics. Here, we introduce the state-dependent stochastic bursting neuron model allowing for a change in its firing patterns independent of changes in its input-output firing rate relationship. Using this model, we show that the effect of single neuron spiking on the network dynamics is contingent on the network activity state. While spike bursting can both generate and disrupt oscillations, these patterns are ineffective in large regions of the network state space in changing the network activity qualitatively. Finally, we show that when single-neuron properties are made dependent on the population activity, a hysteresis like dynamics emerges. This novel phenomenon has important implications for determining the network response to time-varying inputs and for the network sensitivity at different operating points. PMID:27212008

Dynamical state of the network determines the efficacy of single neuron properties in shaping the network activity.

PubMed

Sahasranamam, Ajith; Vlachos, Ioannis; Aertsen, Ad; Kumar, Arvind

2016-05-23

Spike patterns are among the most common electrophysiological descriptors of neuron types. Surprisingly, it is not clear how the diversity in firing patterns of the neurons in a network affects its activity dynamics. Here, we introduce the state-dependent stochastic bursting neuron model allowing for a change in its firing patterns independent of changes in its input-output firing rate relationship. Using this model, we show that the effect of single neuron spiking on the network dynamics is contingent on the network activity state. While spike bursting can both generate and disrupt oscillations, these patterns are ineffective in large regions of the network state space in changing the network activity qualitatively. Finally, we show that when single-neuron properties are made dependent on the population activity, a hysteresis like dynamics emerges. This novel phenomenon has important implications for determining the network response to time-varying inputs and for the network sensitivity at different operating points.

Phase diagram of restricted Boltzmann machines and generalized Hopfield networks with arbitrary priors.

PubMed

Barra, Adriano; Genovese, Giuseppe; Sollich, Peter; Tantari, Daniele

2018-02-01

Restricted Boltzmann machines are described by the Gibbs measure of a bipartite spin glass, which in turn can be seen as a generalized Hopfield network. This equivalence allows us to characterize the state of these systems in terms of their retrieval capabilities, both at low and high load, of pure states. We study the paramagnetic-spin glass and the spin glass-retrieval phase transitions, as the pattern (i.e., weight) distribution and spin (i.e., unit) priors vary smoothly from Gaussian real variables to Boolean discrete variables. Our analysis shows that the presence of a retrieval phase is robust and not peculiar to the standard Hopfield model with Boolean patterns. The retrieval region becomes larger when the pattern entries and retrieval units get more peaked and, conversely, when the hidden units acquire a broader prior and therefore have a stronger response to high fields. Moreover, at low load retrieval always exists below some critical temperature, for every pattern distribution ranging from the Boolean to the Gaussian case.

Natural variation in maternal care and cross-tissue patterns of oxytocin receptor gene methylation in rats.

PubMed

Beery, Annaliese K; McEwen, Lisa M; MacIsaac, Julia L; Francis, Darlene D; Kobor, Michael S

2016-01-01

This article is part of a Special Issue "Parental Care". Since the first report of maternal care effects on DNA methylation in rats, epigenetic modifications of the genome in response to life experience have become the subject of intense focus across many disciplines. Oxytocin receptor expression varies in response to early experience, and both oxytocin signaling and methylation status of the oxytocin receptor gene (Oxtr) in blood have been related to disordered social behavior. It is unknown whether Oxtr DNA methylation varies in response to early life experience, and whether currently employed peripheral measures of Oxtr methylation reflect variation in the brain. We examined the effects of early life rearing experience via natural variation in maternal licking and grooming during the first week of life on behavior, physiology, gene expression, and epigenetic regulation of Oxtr across blood and brain tissues (mononucleocytes, hippocampus, striatum, and hypothalamus). Rats reared by "high" licking-grooming (HL) and "low" licking-grooming (LL) rat dams exhibited differences across study outcomes: LL offspring were more active in behavioral arenas, exhibited lower body mass in adulthood, and showed reduced corticosterone responsivity to a stressor. Oxtr DNA methylation was significantly lower at multiple CpGs in the blood of LL versus HL males, but no differences were found in the brain. Across groups, Oxtr transcript levels in the hypothalamus were associated with reduced corticosterone secretion in response to stress, congruent with the role of oxytocin signaling in this region. Methylation of specific CpGs at a high or low level was consistent across tissues, especially within the brain. However, individual variation in DNA methylation relative to these global patterns was not consistent across tissues. These results suggest that blood Oxtr DNA methylation may reflect early experience of maternal care, and that Oxtr methylation across tissues is highly concordant for specific CpGs, but that inferences across tissues are not supported for individual variation in Oxtr methylation. Copyright © 2015 Elsevier Inc. All rights reserved.

Natural variation in maternal care and cross-tissue patterns of oxytocin receptor gene methylation in rats

PubMed Central

Beery, Annaliese K.; McEwen, Lisa M.; MacIsaac, Julia L; Francis, Darlene D.; Kobor, Michael S.

2015-01-01

Since the first report of maternal care effects on DNA methylation in rats, epigenetic modifications of the genome in response to life experience have become the subject of intense focus across many disciplines. Oxytocin receptor expression varies in response to early experience, and both oxytocin signaling and methylation status of the oxytocin receptor gene (Oxtr) in blood have been related to disordered social behavior. It is unknown whether Oxtr methylation varies in response to early life experience, and whether currently employed peripheral measures of Oxtr methylation reflect variation in the brain. We examined the effects of early life rearing experience via natural variation in maternal licking and grooming during the first week of life on behavior, physiology, gene expression, and epigenetic regulation of Oxtr across blood and brain tissues (mononucleocytes, hippocampus, striatum, and hypothalamus). Rats reared by “high” licking-grooming (HL) and “low” licking-grooming (LL) rat dams exhibited differences across study outcomes: LL offspring were more active in behavioral arenas, exhibited lower body mass in adulthood, and showed reduced corticosterone responsivity to a stressor. Oxtr methylation was significantly lower at multiple CpGs in the blood of LL versus HL rats, but no differences were found in the brain. Across groups, Oxtr transcript levels in the hypothalamus were associated with reduced corticosterone secretion in response to stress, congruent with the role of oxytocin signaling in this region. Methylation of specific CpGs at a high or low level was consistent across tissues, especially within the brain. However, individual variation in methylation relative to these global patterns was not consistent across tissues. These results suggest that blood Oxtr methylation may reflect early experience of maternal care, and that Oxtr methylation across tissues is highly concordant for specific CpGs, but that inferences across tissues are not supported for individual variation in Oxtr methylation. PMID:26122287

Patterns of childhood and adolescent overweight and obesity during health transition in Vanuatu.

PubMed

Dancause, Kelsey N; Vilar, Miguel; Chan, Chim; DeHuff, Christa; Wilson, Michelle; Soloway, Laura E; Tarivonda, Len; Regenvanu, Ralph; Kaneko, Akira; Garruto, Ralph M; Lum, J Koji

2012-01-01

Rapid economic development and subsequent changes in lifestyle and disease burdens ('health transition') is associated with increasing prevalence of obesity among both adults and children. However, because of continued infectious diseases and undernutrition during the early stages of transition, monitoring childhood obesity has not been prioritized in many countries and the scope of the problem is unknown. Therefore we sought to characterize patterns of childhood overweight and obesity in an early transitional area, the South Pacific archipelago of Vanuatu. We completed an anthropometric survey among children from three islands with varying levels of economic development, from rural areas (where adult obesity prevalence is low) to urban areas (where adult obesity prevalence is high). The islands of Ambae (rural), Aneityum (rural with tourism) and Efate (urban). Boys and girls (n 513) aged 6-17 years. Height-, weight- and BMI-for-age did not vary among islands, and prevalence of overweight/obesity based on BMI was low. However, girls from Aneityum - a rural island where the tourism industry increased rapidly after malaria eradication - had increased central adiposity compared with girls from the other islands. This is contrary to adult patterns, which indicate higher obesity prevalence in urban areas. Multiple factors might contribute, including stunting, biological responses after malaria control, sleeping patterns, diet and physical activity levels. Measures of central adiposity highlight an emerging obesity risk among girls in Vanuatu. The data highlight the synergistic relationship among infectious diseases, undernutrition and obesity during the early stages of health transition.

Taxonomy of Individual Variations in Aesthetic Responses to Fractal Patterns

PubMed Central

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

2016-01-01

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

Linking degradation status with ecosystem vulnerability to environmental change

USGS Publications Warehouse

Angeler, David G.; Baho, Didier L.; Allen, Craig R.; Johnson, Richard K.

2015-01-01

Environmental change can cause regime shifts in ecosystems, potentially threatening ecosystem services. It is unclear if the degradation status of ecosystems correlates with their vulnerability to environmental change, and thus the risk of future regime shifts. We assessed resilience in acidified (degraded) and circumneutral (undegraded) lakes with long-term data (1988–2012), using time series modeling. We identified temporal frequencies in invertebrate assemblages, which identifies groups of species whose population dynamics vary at particular temporal scales. We also assessed species with stochastic dynamics, those whose population dynamics vary irregularly and unpredictably over time. We determined the distribution of functional feeding groups of invertebrates within and across the temporal scales identified, and in those species with stochastic dynamics, and assessed attributes hypothesized to contribute to resilience. Three patterns of temporal dynamics, consistent across study lakes, were identified in the invertebrates. The first pattern was one of monotonic change associated with changing abiotic lake conditions. The second and third patterns appeared unrelated to the environmental changes we monitored. Acidified and the circumneutral lakes shared similar levels and patterns of functional richness, evenness, diversity, and redundancy for species within and across the observed temporal scales and for stochastic species groups. These similar resilience characteristics suggest that both lake types did not differ in vulnerability to the environmental changes observed here. Although both lake types appeared equally vulnerable in this study, our approach demonstrates how assessing systemic vulnerability by quantifying ecological resilience can help address uncertainty in predicting ecosystem responses to environmental change across ecosystems.

Complex, non-monotonic dose-response curves with multiple maxima: Do we (ever) sample densely enough?

PubMed

Cvrčková, Fatima; Luštinec, Jiří; Žárský, Viktor

2015-01-01

We usually expect the dose-response curves of biological responses to quantifiable stimuli to be simple, either monotonic or exhibiting a single maximum or minimum. Deviations are often viewed as experimental noise. However, detailed measurements in plant primary tissue cultures (stem pith explants of kale and tobacco) exposed to varying doses of sucrose, cytokinins (BA or kinetin) or auxins (IAA or NAA) revealed that growth and several biochemical parameters exhibit multiple reproducible, statistically significant maxima over a wide range of exogenous substance concentrations. This results in complex, non-monotonic dose-response curves, reminiscent of previous reports of analogous observations in both metazoan and plant systems responding to diverse pharmacological treatments. These findings suggest the existence of a hitherto neglected class of biological phenomena resulting in dose-response curves exhibiting periodic patterns of maxima and minima, whose causes remain so far uncharacterized, partly due to insufficient sampling frequency used in many studies.

Using Citizen Science Observations to Model Species Distributions Over Space, Through Time, and Across Scales

NASA Astrophysics Data System (ADS)

Kelling, S.

2017-12-01

The goal of Biodiversity research is to identify, explain, and predict why a species' distribution and abundance vary through time, space, and with features of the environment. Measuring these patterns and predicting their responses to change are not exercises in curiosity. Today, they are essential tasks for understanding the profound effects that humans have on earth's natural systems, and for developing science-based environmental policies. To gain insight about species' distribution patterns requires studying natural systems at appropriate scales, yet studies of ecological processes continue to be compromised by inadequate attention to scale issues. How spatial and temporal patterns in nature change with scale often reflects fundamental laws of physics, chemistry, or biology, and we can identify such basic, governing laws only by comparing patterns over a wide range of scales. This presentation will provide several examples that integrate bird observations made by volunteers, with NASA Earth Imagery using Big Data analysis techniques to analyze the temporal patterns of bird occurrence across scales—from hemisphere-wide views of bird distributions to the impact of powerful city lights on bird migration.

Tidal Response to Sea-Level Rise in Different Types of Estuaries: The Importance of Length, Bathymetry, and Geometry

NASA Astrophysics Data System (ADS)

Du, Jiabi; Shen, Jian; Zhang, Yinglong J.; Ye, Fei; Liu, Zhuo; Wang, Zhengui; Wang, Ya Ping; Yu, Xin; Sisson, Mac; Wang, Harry V.

2018-01-01

Tidal response to sea-level rise (SLR) varies in different coastal systems. To provide a generic pattern of tidal response to SLR, a systematic investigation was conducted using numerical techniques applied to idealized and realistic estuaries, with model results cross-checked by analytical solutions. Our results reveal that the response of tidal range to SLR is nonlinear, spatially heterogeneous, and highly affected by the length and bathymetry of an estuary and weakly affected by the estuary convergence with an exception of strong convergence. Contrary to the common assumption that SLR leads to a weakened bottom friction, resulting in increased tidal amplitude, we demonstrate that tidal range is likely to decrease in short estuaries and in estuaries with a narrow channel and large low-lying shallow areas.

Signaling mechanisms underlying the robustness and tunability of the plant immune network

PubMed Central

Kim, Yungil; Tsuda, Kenichi; Igarashi, Daisuke; Hillmer, Rachel A.; Sakakibara, Hitoshi; Myers, Chad L.; Katagiri, Fumiaki

2014-01-01

Summary How does robust and tunable behavior emerge in a complex biological network? We sought to understand this for the signaling network controlling pattern-triggered immunity (PTI) in Arabidopsis. A dynamic network model containing four major signaling sectors, the jasmonate, ethylene, PAD4, and salicylate sectors, which together explain up to 80% of the PTI level, was built using data for dynamic sector activities and PTI levels under exhaustive combinatorial sector perturbations. Our regularized multiple regression model had a high level of predictive power and captured known and unexpected signal flows in the network. The sole inhibitory sector in the model, the ethylene sector, was central to the network robustness via its inhibition of the jasmonate sector. The model's multiple input sites linked specific signal input patterns varying in strength and timing to different network response patterns, indicating a mechanism enabling tunability. PMID:24439900

Carbon Nanotube Patterning on a Metal Substrate

NASA Technical Reports Server (NTRS)

Nguyen, Cattien V. (Inventor)

2016-01-01

A CNT electron source, a method of manufacturing a CNT electron source, and a solar cell utilizing a CNT patterned sculptured substrate are disclosed. Embodiments utilize a metal substrate which enables CNTs to be grown directly from the substrate. An inhibitor may be applied to the metal substrate to inhibit growth of CNTs from the metal substrate. The inhibitor may be precisely applied to the metal substrate in any pattern, thereby enabling the positioning of the CNT groupings to be more precisely controlled. The surface roughness of the metal substrate may be varied to control the density of the CNTs within each CNT grouping. Further, an absorber layer and an acceptor layer may be applied to the CNT electron source to form a solar cell, where a voltage potential may be generated between the acceptor layer and the metal substrate in response to sunlight exposure.

Shades of grey; Assessing the contribution of the magno- and parvocellular systems to neural processing of the retinal input in the human visual system from the influence of neural population size and its discharge activity on the VEP.

PubMed

Marcar, Valentine L; Baselgia, Silvana; Lüthi-Eisenegger, Barbara; Jäncke, Lutz

2018-03-01

Retinal input processing in the human visual system involves a phasic and tonic neural response. We investigated the role of the magno- and parvocellular systems by comparing the influence of the active neural population size and its discharge activity on the amplitude and latency of four VEP components. We recorded the scalp electric potential of 20 human volunteers viewing a series of dartboard images presented as a pattern reversing and pattern on-/offset stimulus. These patterns were designed to vary both neural population size coding the temporal- and spatial luminance contrast property and the discharge activity of the population involved in a systematic manner. When the VEP amplitude reflected the size of the neural population coding the temporal luminance contrast property of the image, the influence of luminance contrast followed the contrast response function of the parvocellular system. When the VEP amplitude reflected the size of the neural population responding to the spatial luminance contrast property the image, the influence of luminance contrast followed the contrast response function of the magnocellular system. The latencies of the VEP components examined exhibited the same behavior across our stimulus series. This investigation demonstrates the complex interplay of the magno- and parvocellular systems on the neural response as captured by the VEP. It also demonstrates a linear relationship between stimulus property, neural response, and the VEP and reveals the importance of feedback projections in modulating the ongoing neural response. In doing so, it corroborates the conclusions of our previous study.

An Electrophysiological Index of Perceptual Goodness

PubMed Central

Makin, Alexis D.J.; Wright, Damien; Rampone, Giulia; Palumbo, Letizia; Guest, Martin; Sheehan, Rhiannon; Cleaver, Helen; Bertamini, Marco

2016-01-01

A traditional line of work starting with the Gestalt school has shown that patterns vary in strength and salience; a difference in “Perceptual goodness.” The Holographic weight of evidence model quantifies goodness of visual regularities. The key formula states that W = E/N, where E is number of holographic identities in a pattern and N is number of elements. We tested whether W predicts the amplitude of the neural response to regularity in an extrastriate symmetry-sensitive network. We recorded an Event Related Potential (ERP) generated by symmetry called the Sustained Posterior Negativity (SPN). First, we reanalyzed the published work and found that W explained most variance in SPN amplitude. Then in four new studies, we confirmed specific predictions of the holographic model regarding 1) the differential effects of numerosity on reflection and repetition, 2) the similarity between reflection and Glass patterns, 3) multiple symmetries, and 4) symmetry and anti-symmetry. In all cases, the holographic approach predicted SPN amplitude remarkably well; particularly in an early window around 300–400 ms post stimulus onset. Although the holographic model was not conceived as a model of neural processing, it captures many details of the brain response to symmetry. PMID:27702812

Forest gradient response in Sierran landscapes: the physical template

USGS Publications Warehouse

Urban, Dean L.; Miller, Carol; Halpin, Patrick N.; Stephenson, Nathan L.

2000-01-01

Vegetation pattern on landscapes is the manifestation of physical gradients, biotic response to these gradients, and disturbances. Here we focus on the physical template as it governs the distribution of mixed-conifer forests in California's Sierra Nevada. We extended a forest simulation model to examine montane environmental gradients, emphasizing factors affecting the water balance in these summer-dry landscapes. The model simulates the soil moisture regime in terms of the interaction of water supply and demand: supply depends on precipitation and water storage, while evapotranspirational demand varies with solar radiation and temperature. The forest cover itself can affect the water balance via canopy interception and evapotranspiration. We simulated Sierran forests as slope facets, defined as gridded stands of homogeneous topographic exposure, and verified simulated gradient response against sample quadrats distributed across Sequoia National Park. We then performed a modified sensitivity analysis of abiotic factors governing the physical gradient. Importantly, the model's sensitivity to temperature, precipitation, and soil depth varies considerably over the physical template, particularly relative to elevation. The physical drivers of the water balance have characteristic spatial scales that differ by orders of magnitude. Across large spatial extents, temperature and precipitation as defined by elevation primarily govern the location of the mixed conifer zone. If the analysis is constrained to elevations within the mixed-conifer zone, local topography comes into play as it influences drainage. Soil depth varies considerably at all measured scales, and is especially dominant at fine (within-stand) scales. Physical site variables can influence soil moisture deficit either by affecting water supply or water demand; these effects have qualitatively different implications for forest response. These results have clear implications about purely inferential approaches to gradient analysis, and bear strongly on our ability to use correlative approaches in assessing the potential responses of montane forests to anthropogenic climatic change.

Anthropology. Response to Comment on "Late Pleistocene human skeleton and mtDNA link Paleoamericans and modern Native Americans".

PubMed

Kemp, Brian M; Lindo, John; Bolnick, Deborah A; Malhi, Ripan S; Chatters, James C

2015-02-20

Prüfer and Meyer raise concerns over the mitochondrial DNA (mtDNA) results we reported for the Hoyo Negro individual, citing failure of a portion of these data to conform to their expectations of ancient DNA (aDNA). Because damage patterns in aDNA vary, outright rejection of our findings on this basis is unwarranted, especially in light of our other observations. Copyright © 2015, American Association for the Advancement of Science.

An Evaluation and Comparison of Several Measures of Image Quality for Television Displays

DTIC Science & Technology

1979-01-01

vehicles, buildings, or faces , or they may be artificial much as trn-bar patterns, rectangles, or sine waves. The typical objective image quality assessment...Snyder (1974b) wac able to obtain very good correlations with reaction time and correct responses for a face recognition task. Display quality was varied...recognition versus log JUDA for the target recognition study of Chapter 4, 5) graph of angle oubtended by target at recognitio , versus log JNDA for the

Developmental Differences in Embryos of High and Low Protein Wheat Seeds during Germination 1

PubMed Central

Ching, Te May; Rynd, Lori

1978-01-01

Developmental patterns of embryos from high and low protein wheat (Triticum aestivum) grain produced under varied fertilizer conditions were compared. High protein grain produced seedlings 25% heavier with 25% more total RNA, 30% more DNA, 40% more amino acids, 60% more ribosomes, and 80% more soluble protein content than that of low protein seed. Consistently higher glutamine synthetase and α-amylase and lower acid phosphatase activities were observed in high protein seeds, though the isozyme pattern of α-amylase was not different in the two kinds of seeds. The high total ribosomes and particularly, polysome content observed in high protein seeds may be responsible for the rapid growth and high yield of these seeds. PMID:16660627

Decoding Task and Stimulus Representations in Face-responsive Cortex

PubMed Central

Kliemann, Dorit; Jacoby, Nir; Anzellotti, Stefano; Saxe, Rebecca R.

2017-01-01

Faces provide rich social information about others’ stable traits (e.g., age) and fleeting states of mind (e.g., emotional expression). While some of these facial aspects may be processed automatically, observers can also deliberately attend to some features while ignoring others. It remains unclear how internal goals (e.g., task context) influence the representational geometry of variable and stable facial aspects in face-responsive cortex. We investigated neural response patterns related to decoding i) the intention to attend to a facial aspect before its perception, ii) the attended aspect of a face and iii) stimulus properties. We measured neural responses while subjects watched videos of dynamic positive and negative expressions, and judged the age or the expression’s valence. Split-half multivoxel pattern analyses (MVPA) showed that (i) the intention to attend to a specific aspect of a face can be decoded from left fronto-lateral, but not face-responsive regions; (ii) during face perception, the attend aspect (age vs emotion) could be robustly decoded from almost all face-responsive regions; and (iii) a stimulus property (valence), was represented in right posterior superior temporal sulcus and medial prefrontal cortices. The effect of deliberately shifting the focus of attention on representations suggest a powerful influence of top-down signals on cortical representation of social information, varying across cortical regions, likely reflecting neural flexibility to optimally integrate internal goals and dynamic perceptual input. PMID:27978778

Shiftwork and Diurnal Salivary Cortisol Patterns Among Police Officers

PubMed Central

Charles, Luenda E.; Fekedulegn, Desta; Burchfiel, Cecil M.; Hartley, Tara A.; Andrew, Michael E.; Violanti, John M.; Miller, Diane B.

2016-01-01

Objective To investigate associations between shiftwork and diurnal salivary cortisol among 319 police officers (77.7% men) Methods Information on shiftwork was obtained from the City of Buffalo, NY electronic payroll records. Saliva was collected using Salivettes at seven time points and analyzed for free cortisol concentrations (nmol/L) using a chemiluminescence immunoassay. Mean slopes and areas under the curve were compared across shift schedule using analysis of variance (ANOVA)/analysis of covariance (ANCOVA). Results Officers working primarily on the night shift had a significantly shallower slope. Mean slope (nmol/L/minutes) of the cortisol curve varied significantly across shifts (day: −0.00332 ± 0.00017, afternoon: −0.00313 ± 0.00018, night: −0.00257 ± 0.0002); adjusted P = 0.023. Conclusions Our results suggest that night shiftwork is a work-place factor that may alter the response of the hypothalamic–pituitary–adrenal (HPA) axis to the circadian cues responsible for the pattern of the diurnal cortisol curve. PMID:27129020

Serologic Surveillance of Anthrax in the Serengeti Ecosystem, Tanzania, 1996–2009

PubMed Central

Lembo, Tiziana; Auty, Harriet; Beesley, Cari A.; Bessell, Paul; Packer, Craig; Halliday, Jo; Fyumagwa, Robert; Hoare, Richard; Ernest, Eblate; Mentzel, Christine; Mlengeya, Titus; Stamey, Karen; Wilkins, Patricia P.; Cleaveland, Sarah

2011-01-01

Bacillus anthracis, the bacterium that causes anthrax, is responsible for varying death rates among animal species. Difficulties in case detection, hazardous or inaccessible carcasses, and misdiagnosis hinder surveillance. Using case reports and a new serologic assay that enables multispecies comparisons, we examined exposure to and illness caused by B. anthracis in different species in the Serengeti ecosystem in Tanzania during 1996–2009 and the utility of serosurveillance. High seroprevalence among carnivores suggested regular nonfatal exposure. Seropositive wildebeest and buffalo showed that infection was not invariably fatal among herbivores, whereas absence of seropositivity in zebras and frequent detection of fatal cases indicated high susceptibility. Exposure patterns in dogs reflected known patterns of endemicity and provided new information about anthrax in the ecosystem, which indicated the potential of dogs as indicator species. Serosurveillance is a valuable tool for monitoring and detecting anthrax and may shed light on mechanisms responsible for species-specific variability in exposure, susceptibility, and mortality rates. PMID:21392428

“Enjoy Your Sexuality, but Do it in Secret”: Exploring Undergraduate Women’s Reports of Friends’ Sexual Communications

PubMed Central

Trinh, Sarah L.

2015-01-01

In the current study I used mixed methods to explore the messages that undergraduate women (n = 415) reported receiving from their male and female friends regarding sex and romantic relationships. Reports of friends’ messages varied widely and entailed both support for and criticism of sexual gatekeeping and sex positivity (e.g., sexual agency) and advice regarding sex and romantic relationships. Four individuals, including the author, developed codes to examine this wide range of responses to sexual expectations and prohibitions and independently and reliably coded the data. Response patterns illustrate that reports of female friends’ messages were typically longer and more nuanced than reports of male friends’ messages. Sex-positive messages and sexual gatekeeping messages were frequently reported simultaneously, and this pattern of co-occurrence illustrates the tensions between diverse discourses regarding women’s sexuality. The diversity in reports of friends’ messages challenges popular notions that friends’ influences are wholly problematic and highlights a need for more gender-focused sex education curricula. PMID:27092014

Pupil Dilation to Explicit and Non-Explicit Sexual Stimuli.

PubMed

Watts, Tuesday M; Holmes, Luke; Savin-Williams, Ritch C; Rieger, Gerulf

2017-01-01

Pupil dilation to explicit sexual stimuli (footage of naked and aroused men or women) can elicit sex and sexual orientation differences in sexual response. If similar patterns were replicated with non-explicit sexual stimuli (footage of dressed men and women), then pupil dilation could be indicative of automatic sexual response in fully noninvasive designs. We examined this in 325 men and women with varied sexual orientations to determine whether dilation patterns to non-explicit sexual stimuli resembled those to explicit sexual stimuli depicting the same sex or other sex. Sexual orientation differences in pupil dilation to non-explicit sexual stimuli mirrored those to explicit sexual stimuli. However, the relationship of dilation to non-explicit sexual stimuli with dilation to corresponding explicit sexual stimuli was modest, and effect magnitudes were smaller with non-explicit sexual stimuli than explicit sexual stimuli. The prediction that sexual orientation differences in pupil dilation are larger in men than in women was confirmed with explicit sexual stimuli but not with non-explicit sexual stimuli.

GPU-Accelerated Forward and Back-Projections with Spatially Varying Kernels for 3D DIRECT TOF PET Reconstruction.

PubMed

Ha, S; Matej, S; Ispiryan, M; Mueller, K

2013-02-01

We describe a GPU-accelerated framework that efficiently models spatially (shift) variant system response kernels and performs forward- and back-projection operations with these kernels for the DIRECT (Direct Image Reconstruction for TOF) iterative reconstruction approach. Inherent challenges arise from the poor memory cache performance at non-axis aligned TOF directions. Focusing on the GPU memory access patterns, we utilize different kinds of GPU memory according to these patterns in order to maximize the memory cache performance. We also exploit the GPU instruction-level parallelism to efficiently hide long latencies from the memory operations. Our experiments indicate that our GPU implementation of the projection operators has slightly faster or approximately comparable time performance than FFT-based approaches using state-of-the-art FFTW routines. However, most importantly, our GPU framework can also efficiently handle any generic system response kernels, such as spatially symmetric and shift-variant as well as spatially asymmetric and shift-variant, both of which an FFT-based approach cannot cope with.

GPU-Accelerated Forward and Back-Projections With Spatially Varying Kernels for 3D DIRECT TOF PET Reconstruction

NASA Astrophysics Data System (ADS)

Ha, S.; Matej, S.; Ispiryan, M.; Mueller, K.

2013-02-01

We describe a GPU-accelerated framework that efficiently models spatially (shift) variant system response kernels and performs forward- and back-projection operations with these kernels for the DIRECT (Direct Image Reconstruction for TOF) iterative reconstruction approach. Inherent challenges arise from the poor memory cache performance at non-axis aligned TOF directions. Focusing on the GPU memory access patterns, we utilize different kinds of GPU memory according to these patterns in order to maximize the memory cache performance. We also exploit the GPU instruction-level parallelism to efficiently hide long latencies from the memory operations. Our experiments indicate that our GPU implementation of the projection operators has slightly faster or approximately comparable time performance than FFT-based approaches using state-of-the-art FFTW routines. However, most importantly, our GPU framework can also efficiently handle any generic system response kernels, such as spatially symmetric and shift-variant as well as spatially asymmetric and shift-variant, both of which an FFT-based approach cannot cope with.

Nitrogen use efficiency and crop production: Patterns of regional variation in the United States, 1987-2012.

PubMed

Swaney, Dennis P; Howarth, Robert W; Hong, Bongghi

2018-04-17

National-level summaries of crop production and nutrient use efficiency, important for international comparisons, only partially elucidate agricultural dynamics within a country. Agricultural production and associated environmental impacts in large countries vary significantly because of regional differences in crops, climate, resource use and production practices. Here, we review patterns of regional crop production, nitrogen use efficiency (NUE), and major inputs of nitrogen to US crops over 1987-2012, based on the Farm Resource Regions developed by the Economic Research Service (USDA-ERS). Across the US, NUE generally decreased over time over the period studied, mainly due to increased use in mineral N fertilizer above crop N requirements. The Heartland region dominates production of major crops and thus tends to drive national patterns, showing linear response of crop production to nitrogen inputs broadly consistent with an earlier analysis of global patterns of country-scale data by Lassaletta et al. (2014). Most other regions show similar responses, but the Eastern Uplands region shows a negative response to nitrogen inputs, and the Southern Seaboard shows no significant relationship. The regional differences appear as two branches in the response of aggregate production to N inputs on a cropland area basis, but not on a total area basis, suggesting that the type of scaling used is critical under changing cropland area. Nitrogen use efficiency (NUE) is positively associated with fertilizer as a percentage of N inputs in four regions, and all regions considered together. NUE is positively associated with crop N fixation in all regions except Northern Great Plains. It is negatively associated with manure (livestock excretion); in the US, manure is still treated largely as a waste to be managed rather than a nutrient resource. This significant regional variation in patterns of crop production and NUE vs N inputs, has implications for environmental quality and food security. Copyright © 2018 Elsevier B.V. All rights reserved.

Eliminating the rugosity effect from compensated density logs by geometrical response matching

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

Flaum, C.; Holenka, J.M.; Case, C.R.

1991-06-01

A theoretical and experimental effort to understand the effects of borehole rugosity on individual detector responses yielded an improved method of processing compensated density logs. Historically, the spine/ribs technique for obtaining borehole and mudcake compensation of dual-detector, gamma-gamma density logs has been very successful as long as the borehole and other environmental effects vary slowly with depth and the interest in limited to vertical features broader than several feet. With the increased interest in higher vertical resolution, a more detailed analysis of the effect of such quickly varying environmental effects as rugosity was required. A laboratory setup simulating the effectmore » of rugosity on Schlumberger Litho-Density{sup SM} tools (LDT) was used to study vertical response in the presence of rugosity. The data served as the benchmark for the Nonte Carlo models used to generate synthetic density logs in the presence of more complex rugosity patterns. The results provided in this paper show that proper matching of the two detector responses before application of conventional compensation methods can eliminate rugosity effects without degrading the measurements vertical resolution. The accuracy of the results is a good as the obtained in a parallel mudcake or standoff with the conventional method. Application to both field and synthetic log confirmed the validity of these results.« less

Structural damage detection based on stochastic subspace identification and statistical pattern recognition: II. Experimental validation under varying temperature

NASA Astrophysics Data System (ADS)

Lin, Y. Q.; Ren, W. X.; Fang, S. E.

2011-11-01

Although most vibration-based damage detection methods can acquire satisfactory verification on analytical or numerical structures, most of them may encounter problems when applied to real-world structures under varying environments. The damage detection methods that directly extract damage features from the periodically sampled dynamic time history response measurements are desirable but relevant research and field application verification are still lacking. In this second part of a two-part paper, the robustness and performance of the statistics-based damage index using the forward innovation model by stochastic subspace identification of a vibrating structure proposed in the first part have been investigated against two prestressed reinforced concrete (RC) beams tested in the laboratory and a full-scale RC arch bridge tested in the field under varying environments. Experimental verification is focused on temperature effects. It is demonstrated that the proposed statistics-based damage index is insensitive to temperature variations but sensitive to the structural deterioration or state alteration. This makes it possible to detect the structural damage for the real-scale structures experiencing ambient excitations and varying environmental conditions.

Response of grassland biomass production to simulated climate change and clipping along an elevation gradient.

PubMed

Carlyle, Cameron N; Fraser, Lauchlan H; Turkington, Roy

2014-03-01

Changes in rainfall and temperature regimes are altering plant productivity in grasslands worldwide, and these climate change factors are likely to interact with grassland disturbances, particularly grazing. Understanding how plant production responds to both climate change and defoliation, and how this response varies among grassland types, is important for the long-term sustainability of grasslands. For 4 years, we manipulated temperature [ambient and increased using open-top chambers (OTC)], water (ambient, reduced using rainout shelters and increased using hand watering) and defoliation (clipped, and unclipped) in three grassland types along an elevation gradient. We monitored plant cover and biomass and found that OTC reduced biomass by 15%, but clipping and water treatments interacted with each other and their effects varied in different grassland types. For example, total biomass did not decline in the higher elevation grasslands due to clipping, and water addition mitigated the effects of clipping on subordinate grasses in the lower grasslands. The response of total biomass was driven by dominant plant species while subordinate grasses and forbs showed more variable responses. Overall, our results demonstrate that biomass in the highest elevation grassland was least effected by the treatments and the response of biomass tended to be dependent on interactions between climate change treatments and defoliation. Together, the results suggest that ecosystem function of these grasslands under altered climate patterns will be dependent on site-specific management.

Contrasting stress responses of two co-occurring chipmunk species (Tamias alpinus and T. speciosus).

PubMed

Hammond, Talisin T; Palme, Rupert; Lacey, Eileen A

2015-01-15

Glucocorticoid (GC) hormones are important mediators of responses to environmental conditions. Accordingly, differences in GC physiology may contribute to interspecific variation in response to anthropogenically-induced patterns of climate change. To begin exploring this possibility, we validated the use of fecal cortisol/corticosterone metabolites (FCM) to measure baseline glucocorticoid levels in two species of co-occurring chipmunks that have exhibited markedly different patterns of response to environmental change. In Yosemite National Park, the alpine chipmunk (Tamias alpinus) has undergone a significant upward contraction of its elevational range over the past century; in contrast, the lodgepole chipmunk (Tamiasspeciosus) has experienced no significant change in elevational distribution over this period. To determine if GC levels in these species vary in response to external stimuli and to assess whether these responses differ between species, we compared FCM levels for the same individuals (1) at the time of capture in the field, (2) after a short period of captivity, and (3) after adrenocorticotropic hormone (ACTH), (4) handling, and (5) trapping challenges conducted while these animals were held in captivity. Our analyses indicate that T. alpinus was more responsive to several of these changes in external conditions. Although both species displayed a significant FCM response to ACTH challenge, only T. alpinus showed a significant response to our handling challenge and to captive housing conditions. These findings underscore the importance of species-specific validation studies and support the potential for studies of GC physiology to generate insights into interspecific differences in response to environmental change. Copyright © 2014 Elsevier Inc. All rights reserved.

RadNuc: A graphical user interface to deliver dose rate patterns encountered in nuclear medicine with a 137Cs irradiator

PubMed Central

Pasternack, Jordan B.; Howell, Roger W.

2012-01-01

The temporal variations in absorbed dose rates to organs and tissues in the body are very large in diagnostic and therapeutic nuclear medicine. The response of biological endpoints of relevance to radiation safety and therapeutic efficacy are generally modulated by dose rate. Therefore, it is important to understand how the complex dose rate patterns encountered in nuclear medicine impact relevant biological responses. Accordingly, a graphical user interface (GUI) was created to control a cesium-137 irradiator to deliver such dose rate patterns. Methods Visual Basic 6.0 was used to create a user-friendly GUI to control the dose rate by varying the thickness of a mercury attenuator. The GUI facilitates the delivery of a number of dose rate patterns including constant, exponential increase or decrease, and multi-component exponential. Extensive visual feedback is provided by the GUI during both the planning and delivery stages. Results The GUI controlled irradiator can achieve a maximum dose rate of 40 cGy/hr and a minimum dose rate of 0.01 cGy/hr. Addition of machined lead blocks can be used to further reduce the minimum dose rate to 0.0001 cGy/hr. Measured dose rate patterns differed from programmed dose rate patterns in total dose by 3.2% to 8.4%. Conclusion The GUI controlled irradiator is able to accurately create dose rate patterns encountered in nuclear medicine and other related fields. This makes it an invaluable tool for studying the effects of chronic constant and variable low dose rates on biological tissues in the contexts of both radiation protection and clinical administration of internal radionuclides. PMID:23265668

RadNuc: a graphical user interface to deliver dose rate patterns encountered in nuclear medicine with a 137Cs irradiator.

PubMed

Pasternack, Jordan B; Howell, Roger W

2013-02-01

The temporal variations in absorbed dose rates to organs and tissues in the body are very large in diagnostic and therapeutic nuclear medicine. The response of biological endpoints of relevance to radiation safety and therapeutic efficacy is generally modulated by dose rate. Therefore, it is important to understand how the complex dose rate patterns encountered in nuclear medicine impact relevant biological responses. Accordingly, a graphical user interface (GUI) was created to control a cesium-137 irradiator to deliver such dose rate patterns. Visual Basic 6.0 was used to create a user-friendly GUI to control the dose rate by varying the thickness of a mercury attenuator. The GUI facilitates the delivery of a number of dose rate patterns including constant, exponential increase or decrease, and multi-component exponential. Extensive visual feedback is provided by the GUI during both the planning and delivery stages. The GUI controlled irradiator can achieve a maximum dose rate of 40 cGy/h and a minimum dose rate of 0.01 cGy/h. Addition of machined lead blocks can be used to further reduce the minimum dose rate to 0.0001 cGy/h. Measured dose rate patterns differed from programmed dose rate patterns in total dose by 3.2% to 8.4%. The GUI controlled irradiator is able to accurately create dose rate patterns encountered in nuclear medicine and other related fields. This makes it an invaluable tool for studying the effects of chronic constant and variable low dose rates on biological tissues in the contexts of both radiation protection and clinical administration of internal radionuclides. Copyright © 2013 Elsevier Inc. All rights reserved.

Applicability of common stomatal conductance models in maize under varying soil moisture conditions.

PubMed

Wang, Qiuling; He, Qijin; Zhou, Guangsheng

2018-07-01

In the context of climate warming, the varying soil moisture caused by precipitation pattern change will affect the applicability of stomatal conductance models, thereby affecting the simulation accuracy of carbon-nitrogen-water cycles in ecosystems. We studied the applicability of four common stomatal conductance models including Jarvis, Ball-Woodrow-Berry (BWB), Ball-Berry-Leuning (BBL) and unified stomatal optimization (USO) models based on summer maize leaf gas exchange data from a soil moisture consecutive decrease manipulation experiment. The results showed that the USO model performed best, followed by the BBL model, BWB model, and the Jarvis model performed worst under varying soil moisture conditions. The effects of soil moisture made a difference in the relative performance among the models. By introducing a water response function, the performance of the Jarvis, BWB, and USO models improved, which decreased the normalized root mean square error (NRMSE) by 15.7%, 16.6% and 3.9%, respectively; however, the performance of the BBL model was negative, which increased the NRMSE by 5.3%. It was observed that the models of Jarvis, BWB, BBL and USO were applicable within different ranges of soil relative water content (i.e., 55%-65%, 56%-67%, 37%-79% and 37%-95%, respectively) based on the 95% confidence limits. Moreover, introducing a water response function, the applicability of the Jarvis and BWB models improved. The USO model performed best with or without introducing the water response function and was applicable under varying soil moisture conditions. Our results provide a basis for selecting appropriate stomatal conductance models under drought conditions. Copyright © 2018 Elsevier B.V. All rights reserved.

Model approaches for estimating the influence of time-varying socio-environmental factors on macroparasite transmission in two endemic regions

PubMed Central

ZHONG, BO; CARLTON, ELIZABETH J.; SPEAR, ROBERT C.

2009-01-01

The environmental determinants of vector- and host-borne diseases include time-varying components that modify key transmission parameters, resulting in transient couplings between environmental phenomena and transmission processes. While some time-varying drivers are periodic in nature, some are aperiodic, such as those that involve episodic events or complex patterns of human behavior. Understanding these couplings can allow for prediction of periods of peak infection risk, and ultimately presents opportunities for optimizing intervention selection and timing. Schistosome macroparasites of humans exhibit multiple free-living stages as well as intermediate hosts, and are thus model organisms for illustrating the influence of environmental forcing on transmission. Time-varying environmental factors, termed gating functions, for schistosomes include larval response to temperature and rainfall, seasonal water contact patterns and snail population dynamics driven by weather variables. The biological bases for these modifiers are reviewed, and their values are estimated and incorporated into a transmission model that simulates a multi-year period in two schistosomiasis endemic regions. Modeling results combined with a scale dependent correlation analysis indicate the end effect of these site-specific gating functions is to strongly govern worm burden in these communities, in a manner particularly sensitive to the hydrological differences between sites. Two classes of gating functions were identified, those that act in concert to modify human infection (and determine worm acquisition late in the season), and those that act on snail infection (and determine early season worm acquisition). The importance of these factors for control programs and surveillance is discussed. PMID:20454601

Distribution patterns of the crab Ucides cordatus (Brachyura, Ucididae) at different spatial scales in subtropical mangroves of Paranaguá Bay (southern Brazil)

NASA Astrophysics Data System (ADS)

Sandrini-Neto, L.; Lana, P. C.

2012-06-01

Heterogeneity in the distribution of organisms occurs at a range of spatial scales, which may vary from few centimeters to hundreds of kilometers. The exclusion of small-scale variability from routine sampling designs may confound comparisons at larger scales and lead to inconsistent interpretation of data. Despite its ecological and social-economic importance, little is known about the spatial structure of the mangrove crab Ucides cordatus in the southwest Atlantic. Previous studies have commonly compared densities at relatively broad scales, relying on alleged distribution patterns (e.g., mangroves of distinct composition and structure). We have assessed variability patterns of U. cordatus in mangroves of Paranaguá Bay at four levels of spatial hierarchy (10 s km, km, 10 s m and m) using a nested ANOVA and variance components measures. The potential role of sediment parameters, pneumatophore density, and organic matter content in regulating observed patterns was assessed by multiple regression models. Densities of total and non-commercial size crabs varied mostly at 10 s m to km scales. Densities of commercial size crabs differed at the scales of 10 s m and 10 s km. Variance components indicated that small-scale variation was the most important, contributing up to 70% of the crab density variability. Multiple regression models could not explain the observed variations. Processes driving differences in crab abundance were not related to the measured variables. Small-scale patchy distribution has direct implications to current management practices of U. cordatus. Future studies should consider processes operating at smaller scales, which are responsible for a complex mosaic of patches within previously described patterns.

Spatial analysis of instream nitrogen loads and factors controlling nitrogen delivery to streams in the southeastern United States using spatially referenced regression on watershed attributes (SPARROW) and regional classification frameworks

USGS Publications Warehouse

Hoos, A.B.; McMahon, G.

2009-01-01

Understanding how nitrogen transport across the landscape varies with landscape characteristics is important for developing sound nitrogen management policies. We used a spatially referenced regression analysis (SPARROW) to examine landscape characteristics influencing delivery of nitrogen from sources in a watershed to stream channels. Modelled landscape delivery ratio varies widely (by a factor of 4) among watersheds in the southeastern United States - higher in the western part (Tennessee, Alabama, and Mississippi) than in the eastern part, and the average value for the region is lower compared to other parts of the nation. When we model landscape delivery ratio as a continuous function of local-scale landscape characteristics, we estimate a spatial pattern that varies as a function of soil and climate characteristics but exhibits spatial structure in residuals (observed load minus predicted load). The spatial pattern of modelled landscape delivery ratio and the spatial pattern of residuals coincide spatially with Level III ecoregions and also with hydrologic landscape regions. Subsequent incorporation into the model of these frameworks as regional scale variables improves estimation of landscape delivery ratio, evidenced by reduced spatial bias in residuals, and suggests that cross-scale processes affect nitrogen attenuation on the landscape. The model-fitted coefficient values are logically consistent with the hypothesis that broad-scale classifications of hydrologic response help to explain differential rates of nitrogen attenuation, controlling for local-scale landscape characteristics. Negative model coefficients for hydrologic landscape regions where the primary flow path is shallow ground water suggest that a lower fraction of nitrogen mass will be delivered to streams; this relation is reversed for regions where the primary flow path is overland flow.

Spatial analysis of instream nitrogen loads and factors controlling nitrogen delivery to streams in the southeastern United States using spatially referenced regression on watershed attributes (SPARROW) and regional classification frameworks

USGS Publications Warehouse

Hoos, Anne B.; McMahon, Gerard

2009-01-01

Understanding how nitrogen transport across the landscape varies with landscape characteristics is important for developing sound nitrogen management policies. We used a spatially referenced regression analysis (SPARROW) to examine landscape characteristics influencing delivery of nitrogen from sources in a watershed to stream channels. Modelled landscape delivery ratio varies widely (by a factor of 4) among watersheds in the southeastern United States—higher in the western part (Tennessee, Alabama, and Mississippi) than in the eastern part, and the average value for the region is lower compared to other parts of the nation. When we model landscape delivery ratio as a continuous function of local-scale landscape characteristics, we estimate a spatial pattern that varies as a function of soil and climate characteristics but exhibits spatial structure in residuals (observed load minus predicted load). The spatial pattern of modelled landscape delivery ratio and the spatial pattern of residuals coincide spatially with Level III ecoregions and also with hydrologic landscape regions. Subsequent incorporation into the model of these frameworks as regional scale variables improves estimation of landscape delivery ratio, evidenced by reduced spatial bias in residuals, and suggests that cross-scale processes affect nitrogen attenuation on the landscape. The model-fitted coefficient values are logically consistent with the hypothesis that broad-scale classifications of hydrologic response help to explain differential rates of nitrogen attenuation, controlling for local-scale landscape characteristics. Negative model coefficients for hydrologic landscape regions where the primary flow path is shallow ground water suggest that a lower fraction of nitrogen mass will be delivered to streams; this relation is reversed for regions where the primary flow path is overland flow.

A Complex Story: Universal Preference vs. Individual Differences Shaping Aesthetic Response to Fractals Patterns

PubMed Central

Street, Nichola; Forsythe, Alexandra M.; Reilly, Ronan; Taylor, Richard; Helmy, Mai S.

2016-01-01

Fractal patterns offer one way to represent the rough complexity of the natural world. Whilst they dominate many of our visual experiences in nature, little large-scale perceptual research has been done to explore how we respond aesthetically to these patterns. Previous research (Taylor et al., 2011) suggests that the fractal patterns with mid-range fractal dimensions (FDs) have universal aesthetic appeal. Perceptual and aesthetic responses to visual complexity have been more varied with findings suggesting both linear (Forsythe et al., 2011) and curvilinear (Berlyne, 1970) relationships. Individual differences have been found to account for many of the differences we see in aesthetic responses but some, such as culture, have received little attention within the fractal and complexity research fields. This two-study article aims to test preference responses to FD and visual complexity, using a large cohort (N = 443) of participants from around the world to allow universality claims to be tested. It explores the extent to which age, culture and gender can predict our preferences for fractally complex patterns. Following exploratory analysis that found strong correlations between FD and visual complexity, a series of linear mixed-effect models were implemented to explore if each of the individual variables could predict preference. The first tested a linear complexity model (likelihood of selecting the more complex image from the pair of images) and the second a mid-range FD model (likelihood of selecting an image within mid-range). Results show that individual differences can reliably predict preferences for complexity across culture, gender and age. However, in fitting with current findings the mid-range models show greater consistency in preference not mediated by gender, age or culture. This article supports the established theory that the mid-range fractal patterns appear to be a universal construct underlying preference but also highlights the fragility of universal claims by demonstrating individual differences in preference for the interrelated concept of visual complexity. This highlights a current stalemate in the field of empirical aesthetics. PMID:27252634

The Cell Wall of the Human Fungal Pathogen Aspergillus fumigatus: Biosynthesis, Organization, Immune Response, and Virulence.

PubMed

Latgé, Jean-Paul; Beauvais, Anne; Chamilos, Georgios

2017-09-08

More than 90% of the cell wall of the filamentous fungus Aspergillus fumigatus comprises polysaccharides. Biosynthesis of the cell wall polysaccharides is under the control of three types of enzymes: transmembrane synthases, which are anchored to the plasma membrane and use nucleotide sugars as substrates, and cell wall-associated transglycosidases and glycosyl hydrolases, which are responsible for remodeling the de novo synthesized polysaccharides and establishing the three-dimensional structure of the cell wall. For years, the cell wall was considered an inert exoskeleton of the fungal cell. The cell wall is now recognized as a living organelle, since the composition and cellular localization of the different constitutive cell wall components (especially of the outer layers) vary when the fungus senses changes in the external environment. The cell wall plays a major role during infection. The recognition of the fungal cell wall by the host is essential in the initiation of the immune response. The interactions between the different pattern-recognition receptors (PRRs) and cell wall pathogen-associated molecular patterns (PAMPs) orientate the host response toward either fungal death or growth, which would then lead to disease development. Understanding the molecular determinants of the interplay between the cell wall and host immunity is fundamental to combatting Aspergillus diseases.

Varying Inundation Regimes Differentially Affect Natural and ...

EPA Pesticide Factsheets

Climate change is altering sea-level rise rates and precipitation patterns worldwide. Coastal wetlands are vulnerable to these changes. System responses to stressors are important for resource managers and environmental stewards to understand in order to best manage them. Thin layer sand or sediment application to drowning and eroding marshes is one approach to build elevation and resilience. The above- and below-ground structure, soil carbon dioxide emissions, and pore water constituents in vegetated natural marsh sediments and sand-amended sediments were examined at varying inundation regimes between mean sea level and mean high water (0.82 m NAVD88 to 1.49 m NAVD88) in a field experiment at Laws Point, part of the Plum Island Sound Estuary (MA). Significantly lower salinities, pH, sulfides, phosphates, and ammonium were measured in the sand-amended sediments than in the natural sediments. In natural sediments there was a pattern of increasing salinity with increasing elevation while in the sand-amended sediments the trend was reversed, showing decreasing salinity with increasing elevation. Sulfide concentrations generally increased from low to high inundation with highest concentrations at the highest inundation (i.e., at the lowest elevations). High pore water phosphate concentrations were measured at low elevations in the natural sediments, but the sand-amended treatments had mostly low concentrations of phosphate and no consistent pattern with elevation. A

Prospective-pricing strategies for hospital and departmental effectiveness: the physician's response.

PubMed

Shapleigh, C

1985-10-01

Physician-practice patterns are discussed, and programs of decentralization designed to reduce ancillary use are described. The New England Medical Center (NEMC) conducted a study with two other major hospitals in Boston comparing physician-practice patterns for patients who had had carotid endarterectomies. The indications for surgery for these patients did not appear to be different among the hospitals; however, average charges and length of stay varied considerably. Operating-room time and postoperative management also varied substantially. Strategies to change physician-practice patterns must address the issues of incentives to physicians and hospitals. At NEMC, a program of decentralization is being implemented that involves physician participation in budgeting hospital resources. A program of product pricing has been developed, whereby the NEMC offers an HMO a fixed price for certain kinds of cases upon admission. A daily use report was started to report resource use for specific cases compared with annual medians for that type of case. Case types from many different surgical specialties are involved. The reports show physicians the difference between the actual and expected costs in terms of variances. The NEMC has reoriented its budgeting process to include clinical divisions. Clinical services are planning to budget the use of intermediate products across different cost centers. The clinical budgeting program makes the planning process more objective, lowers the use of ancillary services, and reduces costs.

The gut microbiota appears to compensate for seasonal diet variation in the wild black howler monkey (Alouatta pigra).

PubMed

Amato, Katherine R; Leigh, Steven R; Kent, Angela; Mackie, Roderick I; Yeoman, Carl J; Stumpf, Rebecca M; Wilson, Brenda A; Nelson, Karen E; White, Bryan A; Garber, Paul A

2015-02-01

For most mammals, including nonhuman primates, diet composition varies temporally in response to differences in food availability. Because diet influences gut microbiota composition, it is likely that the gut microbiota of wild mammals varies in response to seasonal changes in feeding patterns. Such variation may affect host digestive efficiency and, ultimately, host nutrition. In this study, we investigate the temporal variation in diet and gut microbiota composition and function in two groups (N = 13 individuals) of wild Mexican black howler monkeys (Alouatta pigra) over a 10-month period in Palenque National Park, Mexico. Temporal changes in the relative abundances of individual bacterial taxa were strongly correlated with changes in host diet. For example, the relative abundance of Ruminococcaceae was highest during periods when energy intake was lowest, and the relative abundance of Butyricicoccus was highest when young leaves and unripe fruit accounted for 68 % of the diet. Additionally, the howlers exhibited increased microbial production of energy during periods of reduced energy intake from food sources. Because we observed few changes in howler activity and ranging patterns during the course of our study, we propose that shifts in the composition and activity of the gut microbiota provided additional energy and nutrients to compensate for changes in diet. Energy and nutrient production by the gut microbiota appears to provide an effective buffer against seasonal fluctuations in energy and nutrient intake for these primates and is likely to have a similar function in other mammal species.

From inter-specific behavioural interactions to species distribution patterns along gradients of habitat heterogeneity.

PubMed

Laiolo, Paola

2013-01-01

The strength of the behavioural processes associated with competitor coexistence may vary when different physical environments, and their biotic communities, come into contact, although empirical evidence of how interference varies across gradients of environmental complexity is still scarce in vertebrates. Here, I analyse how behavioural interactions and habitat selection regulate the local distribution of steppeland larks (Alaudidae) in a gradient from simple to heterogeneous agricultural landscapes in Spain, using crested lark Galerida cristata and Thekla lark G. theklae as study models. Galerida larks significantly partitioned by habitat but frequently co-occurred in heterogeneous environments. Irrespective of habitat divergence, however, the local densities of the two larks were negatively correlated, and the mechanisms beyond this pattern were investigated by means of playback experiments. When simulating the intrusion of the congener by broadcasting the species territorial calls, both larks responded with an aggressive response as intense with respect to warning and approach behaviour as when responding to the intrusion of a conspecific. However, birds promptly responded to playbacks only when congener territories were nearby, a phenomenon that points to learning as the mechanisms through which individuals finely tune their aggressive responses to the local competition levels. Heterospecifics occurred in closer proximity in diverse agro-ecosystems, possibly because of more abundant or diverse resources, and here engage in antagonistic interactions. The drop of species diversity associated with agricultural homogenisation is therefore likely to also bring about the disappearance of the behavioural repertoires associated with species interactions.

Patterns in Greater Sage-grouse population dynamics correspond with public grazing records at broad scales.

PubMed

Monroe, Adrian P; Aldridge, Cameron L; Assal, Timothy J; Veblen, Kari E; Pyke, David A; Casazza, Michael L

2017-06-01

Human land use, such as livestock grazing, can have profound yet varied effects on wildlife interacting within common ecosystems, yet our understanding of land-use effects is often generalized from short-term, local studies that may not correspond with trends at broader scales. Here we used public land records to characterize livestock grazing across Wyoming, USA, and we used Greater Sage-grouse (Centrocercus urophasianus) as a model organism to evaluate responses to livestock management. With annual counts of male Sage-grouse from 743 leks (breeding display sites) during 2004-2014, we modeled population trends in response to grazing level (represented by a relative grazing index) and timing across a gradient in vegetation productivity as measured by the Normalized Vegetation Difference Index (NDVI). We found grazing can have both positive and negative effects on Sage-grouse populations depending on the timing and level of grazing. Sage-grouse populations responded positively to higher grazing levels after peak vegetation productivity, but populations declined when similar grazing levels occurred earlier, likely reflecting the sensitivity of cool-season grasses to grazing during peak growth periods. We also found support for the hypothesis that effects of grazing management vary with local vegetation productivity. These results illustrate the importance of broad-scale analyses by revealing patterns in Sage-grouse population trends that may not be inferred from studies at finer scales, and could inform sustainable grazing management in these ecosystems. © 2017 by the Ecological Society of America.

Patterns in Greater Sage-grouse population dynamics correspond with public grazing records at broad scales

USGS Publications Warehouse

Monroe, Adrian; Aldridge, Cameron L.; Assal, Timothy J.; Veblen, Kari E.; Pyke, David A.; Casazza, Michael L.

2017-01-01

Human land use, such as livestock grazing, can have profound yet varied effects on wildlife interacting within common ecosystems, yet our understanding of land-use effects is often generalized from short-term, local studies that may not correspond with trends at broader scales. Here we used public land records to characterize livestock grazing across Wyoming, USA, and we used Greater Sage-grouse (Centrocercus urophasianus) as a model organism to evaluate responses to livestock management. With annual counts of male Sage-grouse from 743 leks (breeding display sites) during 2004–2014, we modeled population trends in response to grazing level (represented by a relative grazing index) and timing across a gradient in vegetation productivity as measured by the Normalized Vegetation Difference Index (NDVI). We found grazing can have both positive and negative effects on Sage-grouse populations depending on the timing and level of grazing. Sage-grouse populations responded positively to higher grazing levels after peak vegetation productivity, but populations declined when similar grazing levels occurred earlier, likely reflecting the sensitivity of cool-season grasses to grazing during peak growth periods. We also found support for the hypothesis that effects of grazing management vary with local vegetation productivity. These results illustrate the importance of broad-scale analyses by revealing patterns in Sage-grouse population trends that may not be inferred from studies at finer scales, and could inform sustainable grazing management in these ecosystems.

Scaling effects of a graphene field effect transistor for radiation detection

NASA Astrophysics Data System (ADS)

Shollar, Zachary Frank

Radiation detectors based on graphene is a burgeoning research topic within the immense field of graphene research. Although papers continue to parse out their mysteries, the devices remain simplistic and small. New fabrication techniques have allowed for millimeter scale and larger monolayer graphene sheets to be grown with increasingly better quality. It is the goal of this thesis to investigate the scaling effects of millimeter scale graphene for radiation detection purposes. To this end, chemical vapor deposition grown monolayer graphene was purchased and transferred to Si/SiO2 substrates. The devices were patterned into simple rectangular strips varying in size from 3000 x 500 mum, 600 x 100 mum, 300 x 50 mum, and 60 x 11 mum. Four metal contacts were patterned onto each strip for electrical characterization. Two probe resistance measurements were performed on all four sizes, at three different lengths along the graphene. Using the field effect, the graphene resistance response was measured at 0 V back-gate voltage to obtain graphene resistivity on SiO2, which showed an increase in resistivity as the graphene strip size increased. Further, the response was measured for varying back-gate sweep ranges and speeds. This lead to the conclusion that strong p-doping was inherent in the graphene strips, as evidenced by charge neutral points located above +50 V. Strong hysteresis observed in those tests alluded to trapped charge having a major effect on voltage sweeps. Mobility values for the graphene strips were extracted from the back-gate voltage sweeps and fixed gate voltage stabilization curves. Mobility values overall were less than 400 cm2 V-1 s-1, and showed a modest increase in mobility as graphene length increased. Lastly, the largest graphene strip had a light response and radiation response measured. Light response showed a dependence on gate voltage magnitude that favored positive gate voltages, on an n-type Silicon substrate. A saturation effect above +15 V seemed apparent with a resistance increase of only 0.61% +/- 0.062% for +15 V to 0.69% +/- 0.097% for the +50 V back-gate. Response of the largest graphene strip size to forward facing alpha irradiation showed a modest 0.32% +/- 0.082% increase in response, for a -15 V back- gate. Overall, millimeter scale graphene field effect devices showed a light and radiation response, proving their viability. However, results showed fabricated samples had numerous defects and were far from pristine. Fabrication of pristine graphene strips at millimeter scales is of concern. Further work into large scale GFET patterning, testing at more length and width dimensions, and further investigating metal contact and carrier transport in millimeter scales is needed.

Hierarchical classification of dynamically varying radar pulse repetition interval modulation patterns.

PubMed

Kauppi, Jukka-Pekka; Martikainen, Kalle; Ruotsalainen, Ulla

2010-12-01

The central purpose of passive signal intercept receivers is to perform automatic categorization of unknown radar signals. Currently, there is an urgent need to develop intelligent classification algorithms for these devices due to emerging complexity of radar waveforms. Especially multifunction radars (MFRs) capable of performing several simultaneous tasks by utilizing complex, dynamically varying scheduled waveforms are a major challenge for automatic pattern classification systems. To assist recognition of complex radar emissions in modern intercept receivers, we have developed a novel method to recognize dynamically varying pulse repetition interval (PRI) modulation patterns emitted by MFRs. We use robust feature extraction and classifier design techniques to assist recognition in unpredictable real-world signal environments. We classify received pulse trains hierarchically which allows unambiguous detection of the subpatterns using a sliding window. Accuracy, robustness and reliability of the technique are demonstrated with extensive simulations using both static and dynamically varying PRI modulation patterns. Copyright © 2010 Elsevier Ltd. All rights reserved.

Aspen phenylpropanoid genes' expression levels correlate with genets' tannin richness and vary both in responses to soil nitrogen and associations with phenolic profiles.

PubMed

Decker, Vicki H G; Bandau, Franziska; Gundale, Michael J; Cole, Christopher T; Albrectsen, Benedicte R

2017-02-01

Condensed tannin (CT) contents of European aspen (Populus tremula L.) vary among genotypes, and increases in nitrogen (N) availability generally reduce plants' tannin production in favor of growth, through poorly understood mechanisms. We hypothesized that intrinsic tannin production rates may co-vary with gene expression responses to soil N and resource allocation within the phenylpropanoid pathway (PPP). Thus, we examined correlations between soil N levels and both expression patterns of eight PPP genes (measured by quantitative-reverse transcription PCR) and foliar phenolic compounds (measured by liquid chromatography-mass spectrometry) in young aspen genets with intrinsically extreme CT levels. Monitored phenolics included salicinoids, lignins, flavones, flavonols, CT precursors and CTs. The PPP genes were consistently expressed more strongly in high-CT trees. Low N supplements reduced expression of genes throughout the PPP in all genets, while high N doses restored expression of genes at the beginning and end of the pathway. These PPP changes were not reflected in pools of tannin precursors, but varying correlations between gene expression and foliar phenolic pools were detected in young and mature leaves, suggesting that processes linking gene expression and the resulting phenolics vary spatially and temporally. Precursor fluxes suggested that CT-related metabolic rate or sink controls are linked to intrinsic carbon allocation strategies associated with N responses. Overall, we found more negative correlations (indicative of allocation trade-offs) between PPP gene expression and phenolic products following N additions in low-CT plants than in high-CT plants. The tannin-related expression dynamics suggest that, in addition to defense, relative tannin levels may also be indicative of intraspecific variations in the way aspen genets respond to soil fertility. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Children’s Processing and Comprehension of Complex Sentences Containing Temporal Connectives: The Influence of Memory on the Time Course of Accurate Responses

PubMed Central

2016-01-01

In a touch-screen paradigm, we recorded 3- to 7-year-olds’ (N = 108) accuracy and response times (RTs) to assess their comprehension of 2-clause sentences containing before and after. Children were influenced by order: performance was most accurate when the presentation order of the 2 clauses matched the chronological order of events: “She drank the juice, before she walked in the park” (chronological order) versus “Before she walked in the park, she drank the juice” (reverse order). Differences in RTs for correct responses varied by sentence type: accurate responses were made more speedily for sentences that afforded an incremental processing of meaning. An independent measure of memory predicted this pattern of performance. We discuss these findings in relation to children’s knowledge of connective meaning and the processing requirements of sentences containing temporal connectives. PMID:27690492

Crushing motor patterns in drum (Teleostei: Sciaenidae): functional novelties associated with molluscivory.

PubMed

Grubich, J R

2000-10-01

This study explores the evolution of molluscivory in the marine teleost family Sciaenidae by comparing the motor activity patterns of the pharyngeal muscles of two closely related taxa, the molluscivorous black drum (Pogonias cromis) and the generalist red drum (Sciaenops ocellatus). Muscle activity patterns were recorded simultaneously from eight pharyngeal muscles. Electromyographic (EMG) activity was recorded during feeding on three prey types that varied in shell hardness. Canonical variate and discriminant function analyses were used to describe the distinctness of drum pharyngeal processing behaviors. Discriminant functions built of EMG timing variables were more accurate than muscle activity intensity at identifying cycles by prey type and species. Both drum species demonstrated the ability to modulate pharyngeal motor patterns in response to prey hardness. The mean motor patterns and the canonical variate space of crushing behavior indicated that black drum employed a novel motor pattern during molluscivory. The mollusc-crushing motor pattern of black drum is different from other neoteleost pharyngeal behaviors in lacking upper jaw retraction by the retractor dorsalis muscle. This functional modification suggests that crushing hard-shelled marine bivalves requires a 'vice-like' compression bite in contrast to the shearing forces that are applied to weaker-shelled fiddler crabs by red drum and to freshwater snails by redear sunfish.

Size-mediated response to public cues of predation risk in a tropical stream fish.

PubMed

Elvidge, C K; Ramnarine, I W; Godin, J-G J; Brown, G E

2010-11-01

In order to investigate any size-dependent differences between behavioural patterns, wild-caught Hart's rivulus Rivulus hartii of varying sizes were exposed to chemical alarm cues extracted from the skin of conspecifics or heterospecific Poecilia reticulata, or a tank water control, in a series of laboratory trials. In response to conspecific alarm cues, R. hartii subjects of the range of body sizes tested exhibited consistent, size-independent antipredator behaviours that were characterized by decreased locomotory activity and foraging levels and increased refuging behaviour. Conversely, focal R. hartii demonstrated significant size-dependent trends in response to heterospecific alarm cues, with smaller individuals exhibiting antipredator responses and larger individuals shifting their behaviour to increased levels of activity consistent with a foraging, or predatory, response. These results show that the behavioural responses of individual R. hartii to publicly available chemical alarm cues from heterospecifics are mediated by the size of the receiver. © 2010 The Authors. Journal of Fish Biology © 2010 The Fisheries Society of the British Isles.

Depression history as a moderator of relations between cortisol and shame responses to social-evaluative threat in young adults.

PubMed

Hellman, Natalie; Morris, Matthew C; Rao, Uma; Garber, Judy

2015-07-01

Changes in cortisol and shame are commonly elicited by psychosocial stressors involving social-evaluative threat. According to social self preservation theory, this coordinated psychobiological response is adaptive. Individuals with a history of depression, however, may exhibit diminished cortisol reactivity to acute stressors, which could interfere with coordinated cortisol and shame responses. The present study examined temporal relations between cortisol and shame responses to a psychosocial stress task in young adults who varied in their history of depression (56 remitted-depressed, 46 never-depressed). Lagged effects multilevel models revealed that depression history moderated relations between cortisol levels and shame ratings 25-55min later. The pattern of these interactions was similar: whereas higher cortisol levels predicted increases in shame in never-depressed individuals, cortisol levels were unrelated to shame responses in remitted-depressed individuals. Findings suggest a dissociation between cortisol and shame responses to stress in individuals with a history of depression. Copyright © 2015 Elsevier B.V. All rights reserved.

Architecture of a minimal signaling pathway explains the T-cell response to a 1 million-fold variation in antigen affinity and dose

PubMed Central

Lever, Melissa; Lim, Hong-Sheng; Kruger, Philipp; Nguyen, John; Trendel, Nicola; Abu-Shah, Enas; Maini, Philip Kumar; van der Merwe, Philip Anton

2016-01-01

T cells must respond differently to antigens of varying affinity presented at different doses. Previous attempts to map peptide MHC (pMHC) affinity onto T-cell responses have produced inconsistent patterns of responses, preventing formulations of canonical models of T-cell signaling. Here, a systematic analysis of T-cell responses to 1 million-fold variations in both pMHC affinity and dose produced bell-shaped dose–response curves and different optimal pMHC affinities at different pMHC doses. Using sequential model rejection/identification algorithms, we identified a unique, minimal model of cellular signaling incorporating kinetic proofreading with limited signaling coupled to an incoherent feed-forward loop (KPL-IFF) that reproduces these observations. We show that the KPL-IFF model correctly predicts the T-cell response to antigen copresentation. Our work offers a general approach for studying cellular signaling that does not require full details of biochemical pathways. PMID:27702900

Architecture of a minimal signaling pathway explains the T-cell response to a 1 million-fold variation in antigen affinity and dose.

PubMed

Lever, Melissa; Lim, Hong-Sheng; Kruger, Philipp; Nguyen, John; Trendel, Nicola; Abu-Shah, Enas; Maini, Philip Kumar; van der Merwe, Philip Anton; Dushek, Omer

2016-10-25

T cells must respond differently to antigens of varying affinity presented at different doses. Previous attempts to map peptide MHC (pMHC) affinity onto T-cell responses have produced inconsistent patterns of responses, preventing formulations of canonical models of T-cell signaling. Here, a systematic analysis of T-cell responses to 1 million-fold variations in both pMHC affinity and dose produced bell-shaped dose-response curves and different optimal pMHC affinities at different pMHC doses. Using sequential model rejection/identification algorithms, we identified a unique, minimal model of cellular signaling incorporating kinetic proofreading with limited signaling coupled to an incoherent feed-forward loop (KPL-IFF) that reproduces these observations. We show that the KPL-IFF model correctly predicts the T-cell response to antigen copresentation. Our work offers a general approach for studying cellular signaling that does not require full details of biochemical pathways.

Using polynomials to simplify fixed pattern noise and photometric correction of logarithmic CMOS image sensors.

PubMed

Li, Jing; Mahmoodi, Alireza; Joseph, Dileepan

2015-10-16

An important class of complementary metal-oxide-semiconductor (CMOS) image sensors are those where pixel responses are monotonic nonlinear functions of light stimuli. This class includes various logarithmic architectures, which are easily capable of wide dynamic range imaging, at video rates, but which are vulnerable to image quality issues. To minimize fixed pattern noise (FPN) and maximize photometric accuracy, pixel responses must be calibrated and corrected due to mismatch and process variation during fabrication. Unlike literature approaches, which employ circuit-based models of varying complexity, this paper introduces a novel approach based on low-degree polynomials. Although each pixel may have a highly nonlinear response, an approximately-linear FPN calibration is possible by exploiting the monotonic nature of imaging. Moreover, FPN correction requires only arithmetic, and an optimal fixed-point implementation is readily derived, subject to a user-specified number of bits per pixel. Using a monotonic spline, involving cubic polynomials, photometric calibration is also possible without a circuit-based model, and fixed-point photometric correction requires only a look-up table. The approach is experimentally validated with a logarithmic CMOS image sensor and is compared to a leading approach from the literature. The novel approach proves effective and efficient.

Epigenetic response to environmental change: DNA methylation varies with invasion status.

PubMed

Schrey, Aaron W; Robbins, Travis R; Lee, Jacob; Dukes, David W; Ragsdale, Alexandria K; Thawley, Christopher J; Langkilde, Tracy

2016-04-01

Epigenetic mechanisms may be important for a native species' response to rapid environmental change. Red Imported Fire Ants ( Solenopsis invicta Santschi, 1916) were recently introduced to areas occupied by the Eastern Fence Lizard ( Sceloporus undulatus Bosc & Daudin, 1801). Behavioral, morphological and physiological phenotypes of the Eastern Fence Lizard have changed following invasion, creating a natural biological system to investigate environmentally induced epigenetic changes. We tested for variation in DNA methylation patterns in Eastern Fence Lizard populations associated with different histories of invasion by Red Imported Fire Ants. At methylation sensitive amplified fragment length polymorphism loci, we detected a higher diversity of methylation in Eastern Fence Lizard populations from Fire Ant uninvaded versus invaded sites, and uninvaded sites had higher methylation. Our results suggest that invasive species may alter methylation frequencies and the pattern of methylation among native individuals. While our data indicate a high level of intrinsic variability in DNA methylation, DNA methylation at some genomic loci may underlie observed phenotypic changes in Eastern Fence Lizard populations in response to invasion of Red Imported Fire Ants. This process may be important in facilitating adaptation of native species to novel pressures imposed by a rapidly changing environment.

Evolution of bioconvective patterns in variable gravity

NASA Technical Reports Server (NTRS)

Noever, David A.

1991-01-01

Measurements are reported of the evolution of bioconvective patterns in shallow, dense cultures of microorganisms subjected to varying gravity. Various statistical properties of this random, quasi-two-dimensional structure have been found: Aboav's law is obeyed, the average vertex angles follow predictions for regular polygons, and the area of a pattern varies linearly with its number of sides. As gravity varies between 1 g and 1.8 g, these statistical properties continue to hold despite a tripling of the number of polygons and a reduced average polygon dimension by a third. This work compares with experiments on soap foams, Langmuir monolayer foams, metal grains, and simulations.

Shorebird Migration Patterns in Response to Climate Change: A Modeling Approach

NASA Technical Reports Server (NTRS)

Smith, James A.

2010-01-01

The availability of satellite remote sensing observations at multiple spatial and temporal scales, coupled with advances in climate modeling and information technologies offer new opportunities for the application of mechanistic models to predict how continental scale bird migration patterns may change in response to environmental change. In earlier studies, we explored the phenotypic plasticity of a migratory population of Pectoral sandpipers by simulating the movement patterns of an ensemble of 10,000 individual birds in response to changes in stopover locations as an indicator of the impacts of wetland loss and inter-annual variability on the fitness of migratory shorebirds. We used an individual based, biophysical migration model, driven by remotely sensed land surface data, climate data, and biological field data. Mean stop-over durations and stop-over frequency with latitude predicted from our model for nominal cases were consistent with results reported in the literature and available field data. In this study, we take advantage of new computing capabilities enabled by recent GP-GPU computing paradigms and commodity hardware (general purchase computing on graphics processing units). Several aspects of our individual based (agent modeling) approach lend themselves well to GP-GPU computing. We have been able to allocate compute-intensive tasks to the graphics processing units, and now simulate ensembles of 400,000 birds at varying spatial resolutions along the central North American flyway. We are incorporating additional, species specific, mechanistic processes to better reflect the processes underlying bird phenotypic plasticity responses to different climate change scenarios in the central U.S.

Changes in pitch height elicit both language universal and language dependent changes in neural representation of pitch in the brainstem and auditory cortex

PubMed Central

Krishnan, Ananthanarayan; Suresh, Chandan H.; Gandour, Jackson T.

2017-01-01

Language experience shapes encoding of pitch-relevant information at both brainstem and cortical levels of processing. Pitch height is a salient dimension that orders pitch from low to high. Herein we investigate the effects of language experience (Chinese, English) in the brainstem and cortex on i) neural responses to variations in pitch height, ii) presence of asymmetry in cortical pitch representation, and iii) patterns of relative changes in magnitude of pitch height between these two levels of brain structure. Stimuli were three nonspeech homologs of Mandarin Tone 2 varying in pitch height only. The frequency-following response (FFR) and the cortical pitch-specific response (CPR) were recorded concurrently. At the Fz-linked T7/T8 site, peak latency of Na, Pb, and Nb decreased with increasing pitch height for both groups. Peak-to-peak amplitude of Na–Pb and Pb–Nb increased with increasing pitch height across groups. A language-dependent effect was restricted to Na-Pb; the Chinese had larger amplitude than the English group. At temporal sites (T7/T8), the Chinese group had larger amplitude, as compared to English, across stimuli, but also limited to the Na-Pb component and right temporal site. In the brainstem, F0 magnitude decreased with increasing pitch height; Chinese had larger magnitude across stimuli. A comparison of CPR and FFR responses revealed distinct patterns of relative changes in magnitude common to both groups. CPR amplitude increased and FFR amplitude decreased with increasing pitch height. Experience-dependent effects on CPR components vary as a function of neural sensitivity to pitch height within a particular temporal window (Na–Pb). Differences between the auditory brainstem and cortex imply distinct neural mechanisms for pitch extraction at both levels of brain structure. PMID:28108254

Changes in pitch height elicit both language-universal and language-dependent changes in neural representation of pitch in the brainstem and auditory cortex.

PubMed

Krishnan, Ananthanarayan; Suresh, Chandan H; Gandour, Jackson T

2017-03-27

Language experience shapes encoding of pitch-relevant information at both brainstem and cortical levels of processing. Pitch height is a salient dimension that orders pitch from low to high. Herein we investigate the effects of language experience (Chinese, English) in the brainstem and cortex on (i) neural responses to variations in pitch height, (ii) presence of asymmetry in cortical pitch representation, and (iii) patterns of relative changes in magnitude of pitch height between these two levels of brain structure. Stimuli were three nonspeech homologs of Mandarin Tone 2 varying in pitch height only. The frequency-following response (FFR) and the cortical pitch-specific response (CPR) were recorded concurrently. At the Fz-linked T7/T8 site, peak latency of Na, Pb, and Nb decreased with increasing pitch height for both groups. Peak-to-peak amplitude of Na-Pb and Pb-Nb increased with increasing pitch height across groups. A language-dependent effect was restricted to Na-Pb; the Chinese had larger amplitude than the English group. At temporal sites (T7/T8), the Chinese group had larger amplitude, as compared to English, across stimuli, but also limited to the Na-Pb component and right temporal site. In the brainstem, F0 magnitude decreased with increasing pitch height; Chinese had larger magnitude across stimuli. A comparison of CPR and FFR responses revealed distinct patterns of relative changes in magnitude common to both groups. CPR amplitude increased and FFR amplitude decreased with increasing pitch height. Experience-dependent effects on CPR components vary as a function of neural sensitivity to pitch height within a particular temporal window (Na-Pb). Differences between the auditory brainstem and cortex imply distinct neural mechanisms for pitch extraction at both levels of brain structure. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Where and When do Species Interactions Set Range Limits?

PubMed

Louthan, Allison M; Doak, Daniel F; Angert, Amy L

2015-12-01

A long-standing theory, originating with Darwin, suggests that abiotic forces set species range limits at high latitude, high elevation, and other abiotically 'stressful' areas, while species interactions set range limits in apparently more benign regions. This theory is of considerable importance for both basic and applied ecology, and while it is often assumed to be a ubiquitous pattern, it has not been clearly defined or broadly tested. We review tests of this idea and dissect how the strength of species interactions must vary across stress gradients to generate the predicted pattern. We conclude by suggesting approaches to better test this theory, which will deepen our understanding of the forces that determine species ranges and govern responses to climate change. Copyright © 2015 Elsevier Ltd. All rights reserved.

Sequential and selective localized optical heating in water via on-chip dielectric nanopatterning.

PubMed

Morsy, Ahmed M; Biswas, Roshni; Povinelli, Michelle L

2017-07-24

We study the use of nanopatterned silicon membranes to obtain optically-induced heating in water. We show that by varying the detuning between an absorptive optical resonance of the patterned membrane and an illumination laser, both the magnitude and response time of the temperature rise can be controlled. This allows for either sequential or selective heating of different patterned areas on chip. We obtain a steady-state temperature of approximately 100 °C for a 805.5nm CW laser power density of 66 µW/μm 2 and observe microbubble formation. The ability to spatially and temporally control temperature on the microscale should enable the study of heat-induced effects in a variety of chemical and biological lab-on-chip applications.

Magnetic imaging of cyanide-bridged co-ordination nanoparticles grafted on FIB-patterned Si substrates.

PubMed

Ghirri, Alberto; Candini, Andrea; Evangelisti, Marco; Gazzadi, Gian Carlo; Volatron, Florence; Fleury, Benoit; Catala, Laure; David, Christophe; Mallah, Talal; Affronte, Marco

2008-12-01

Prussian blue CsNiCr nanoparticles are used to decorate selected portions of a Si substrate. For successful grafting to take place, the Si surface needs first to be chemically functionalized. Low-dose focused ion beam patterning on uniformly functionalized surfaces selects those portions that will not participate in the grafting process. Step-by-step control is assured by atomic force and high-resolution scanning electron microscopy, revealing a submonolayer distribution of the grafted nanoparticles. By novel scanning Hall-probe microscopy, an in-depth investigation of the magnetic response of the nanoparticles to varying temperature and applied magnetic field is provided. The magnetic images acquired suggest that low-temperature canted ferromagnetism is found in the grafted nanoparticles, similar to what is observed in the equivalent bulk material.

The family receiving home care: functional health pattern assessment.

PubMed

Hooper, J I

1996-01-01

The winds of change in health care make assessment of the family more important than ever as a tool for health care providers seeking to assist the family move themselves toward high-level wellness. Limited medical care and imposed self-responsibility for health promotion and illness prevention, which are natural consequences of these changes, move the locus of control for health management back to the family. The family's teachings, modeling, and interactions are greater influences than ever on the health of the patient. Gordon's functional health patterns provide a holistic model for assessment of the family because assessment data are classified under 11 headings: health perception and health management, nutritional-metabolic, elimination, activity and exercise, sleep and rest, cognition and perception, self-perception and self-concept, roles and relationships, sexuality and reproduction, coping and stress tolerance, and values and beliefs. Questions posed under each of the health patterns can be varied to reflect the uniqueness of the individual family as well as to inquire about family strengths and weaknesses in all patterns. Data using this model provide a comprehensive base for including the family in designing a plan of care.

How grow-and-switch gravitropism generates root coiling and root waving growth responses in Medicago truncatula.

PubMed

Tan, Tzer Han; Silverberg, Jesse L; Floss, Daniela S; Harrison, Maria J; Henley, Christopher L; Cohen, Itai

2015-10-20

Experimental studies show that plant root morphologies can vary widely from straight gravity-aligned primary roots to fractal-like root architectures. However, the opaqueness of soil makes it difficult to observe how environmental factors modulate these patterns. Here, we combine a transparent hydrogel growth medium with a custom built 3D laser scanner to directly image the morphology of Medicago truncatula primary roots. In our experiments, root growth is obstructed by an inclined plane in the growth medium. As the tilt of this rigid barrier is varied, we find Medicago transitions between randomly directed root coiling, sinusoidal root waving, and normal gravity-aligned morphologies. Although these root phenotypes appear morphologically distinct, our analysis demonstrates the divisions are less well defined, and instead, can be viewed as a 2D biased random walk that seeks the path of steepest decent along the inclined plane. Features of this growth response are remarkably similar to the widely known run-and-tumble chemotactic behavior of Escherichia coli bacteria, where biased random walks are used as optimal strategies for nutrient uptake.

Response of mixed-phase boundary layer clouds with rapid and slow ice nucleation processes to cloud-top temperature trend

NASA Astrophysics Data System (ADS)

Fridlind, A. M.; Avramov, A.; Ackerman, A. S.; Alpert, P. A.; Knopf, D. A.; DeMott, P. J.; Brooks, S. D.; Glen, A.

2015-12-01

It has been argued on the basis of some laboratory data sets, observed mixed-phase cloud systems, and numerical modeling studies that weakly active or slowly consumed ice forming nuclei (IFN) may be important to natural cloud systems. It has also been argued on the basis of field measurements that ice nucleation under mixed-phase conditions appears to occur predominantly via a liquid-phase mechanism, requiring the presence of liquid droplets prior to substantial ice nucleation. Here we analyze the response of quasi-Lagrangian large-eddy simulations of mixed-phase cloud layers to IFN operating via a liquid-phase mode using assumptions that result in either slow or rapid depletion of IFN from the cloudy boundary layer. Using several generalized case studies that do not exhibit riming or drizzle, based loosely on field campaign data, we vary environmental conditions such that the cloud-top temperature trend varies. One objective of this work is to identify differing patterns in ice formation intensity that may be distinguishable from ground-based or satellite platforms.

Developmental differences in the neural mechanisms of facial emotion labeling

PubMed Central

Adleman, Nancy E.; Kim, Pilyoung; Oakes, Allison H.; Hsu, Derek; Reynolds, Richard C.; Chen, Gang; Pine, Daniel S.; Brotman, Melissa A.; Leibenluft, Ellen

2016-01-01

Adolescence is a time of increased risk for the onset of psychological disorders associated with deficits in face emotion labeling. We used functional magnetic resonance imaging (fMRI) to examine age-related differences in brain activation while adolescents and adults labeled the emotion on fearful, happy and angry faces of varying intensities [0% (i.e. neutral), 50%, 75%, 100%]. Adolescents and adults did not differ on accuracy to label emotions. In the superior temporal sulcus, ventrolateral prefrontal cortex and middle temporal gyrus, adults show an inverted-U-shaped response to increasing intensities of fearful faces and a U-shaped response to increasing intensities of happy faces, whereas adolescents show the opposite patterns. In addition, adults, but not adolescents, show greater inferior occipital gyrus activation to negative (angry, fearful) vs positive (happy) emotions. In sum, when subjects classify subtly varying facial emotions, developmental differences manifest in several ‘ventral stream’ brain regions. Charting the typical developmental course of the brain mechanisms of socioemotional processes, such as facial emotion labeling, is an important focus for developmental psychopathology research. PMID:26245836

Fungal and host transcriptome analysis of pH-regulated genes during colonization of apple fruits by Penicillium expansum.

PubMed

Barad, Shiri; Sela, Noa; Kumar, Dilip; Kumar-Dubey, Amit; Glam-Matana, Nofar; Sherman, Amir; Prusky, Dov

2016-05-04

Penicillium expansum is a destructive phytopathogen that causes decay in deciduous fruits during postharvest handling and storage. During colonization the fungus secretes D-gluconic acid (GLA), which modulates environmental pH and regulates mycotoxin accumulation in colonized tissue. Till now no transcriptomic analysis has addressed the specific contribution of the pathogen's pH regulation to the P. expansum colonization process. For this purpose total RNA from the leading edge of P. expansum-colonized apple tissue of cv. 'Golden Delicious' and from fungal cultures grown under pH 4 or 7 were sequenced and their gene expression patterns were compared. We present a large-scale analysis of the transcriptome data of P. expansum and apple response to fungal colonization. The fungal analysis revealed nine different clusters of gene expression patterns that were divided among three major groups in which the colonized tissue showed, respectively: (i) differing transcript expression patterns between mycelial growth at pH 4 and pH 7; (ii) similar transcript expression patterns of mycelial growth at pH 4; and (iii) similar transcript expression patterns of mycelial growth at pH 7. Each group was functionally characterized in order to decipher genes that are important for pH regulation and also for colonization of apple fruits by Penicillium. Furthermore, comparison of gene expression of healthy apple tissue with that of colonized tissue showed that differentially expressed genes revealed up-regulation of the jasmonic acid and mevalonate pathways, and also down-regulation of the glycogen and starch biosynthesis pathways. Overall, we identified important genes and functionalities of P. expansum that were controlled by the environmental pH. Differential expression patterns of genes belonging to the same gene family suggest that genes were selectively activated according to their optimal environmental conditions (pH, in vitro or in vivo) to enable the fungus to cope with varying conditions and to make optimal use of available enzymes. Comparison between the activation of the colonized host's gene responses by alkalizing Colletotrichum gloeosporioides and acidifying P. expansum pathogens indicated similar gene response patterns, but stronger responses to P. expansum, suggesting the importance of acidification by P. expansum as a factor in its increased aggressiveness.

Lipopolysaccharide Clearance, Bacterial Clearance, and Systemic Inflammatory Responses Are Regulated by Cell Type–Specific Functions of TLR4 during Sepsis

PubMed Central

Deng, Meihong; Loughran, Patricia; Gibson, Gregory; Sodhi, Chhinder; Watkins, Simon; Hackam, David

2013-01-01

The morbidity associated with bacterial sepsis is the result of host immune responses to pathogens, which are dependent on pathogen recognition by pattern recognition receptors, such as TLR4. TLR4 is expressed on a range of cell types, yet the mechanisms by which cell-specific functions of TLR4 lead to an integrated sepsis response are poorly understood. To address this, we generated mice in which TLR4 was specifically deleted from myeloid cells (LysMTLR4KO) or hepatocytes (HCTLR4KO) and then determined survival, bacterial counts, host inflammatory responses, and organ injury in a model of cecal ligation and puncture (CLP), with or without antibiotics. LysM-TLR4 was required for phagocytosis and efficient bacterial clearance in the absence of antibiotics. Survival, the magnitude of the systemic and local inflammatory responses, and liver damage were associated with bacterial levels. HCTLR4 was required for efficient LPS clearance from the circulation, and deletion of HCTLR4 was associated with enhanced macrophage phagocytosis, lower bacterial levels, and improved survival in CLP without antibiotics. Antibiotic administration during CLP revealed an important role for hepatocyte LPS clearance in limiting sepsis-induced inflammation and organ injury. Our work defines cell type–selective roles for TLR4 in coordinating complex immune responses to bacterial sepsis and suggests that future strategies for modulating microbial molecule recognition should account for varying roles of pattern recognition receptors in multiple cell populations. PMID:23562812

Tuning operating temperature of BaSnO3 gas sensor for reducing and oxidizing gases

NASA Astrophysics Data System (ADS)

Kumar, Sachin; Pugh, David; Dasgupta, Daipayan; Sarin, Neha; Parkin, Ivan; Luthra, Vandna

2018-05-01

Barium stannate (BaSnO3) was prepared by solid state ceramic route. The crystalline phase of the prepared sample was confirmed by X-Ray Diffraction (XRD) pattern. Gas sensing behaviour of barium stannate was investigated for reducing and oxidizing gases; such as butane, ethanol, CO and NO2; from 5 ppm to 50 ppm levels of concentration. Barium stannate sensors were optimized for highest responsiveness by varying operating temperature between 270 °C to 550 °C. Its highest response was observed for ethanol at 300°C. The gas sensing response of ethanol was better than other gases at all the operating temperatures. Such studies in conjunction with gas sensing tests can be used for setting the optimum operating temperatures and can be used for low concentration ethanol sensing applications.

Practice Research: General practitioners' awareness of colorectal cancer

PubMed Central

Nichols, Sally

1986-01-01

A survey was carried out in Portsmouth to find out what general practitioners knew about colorectal cancer and what their views were on screening. A random sample of general practitioners was interviewed by questionnaire and the remainder asked to complete the questionnaire themselves. The overall response rate was 62%. There was a higher response rate from women doctors and from the group that was interviewed. For some questions there was a difference in the pattern of responses given by the interview group and the group who completed the questionnaire themselves. The level of knowledge of colorectal cancer varied according to which aspect was questioned. The general practitioners knew the symptoms well but were less aware of the vital statistics and risk factors. Most doctors were not in favour of screening by testing for faecal occult blood. PMID:3080150

The robustness of false memory for emotional pictures.

PubMed

Bessette-Symons, Brandy A

2018-02-01

Emotional material is commonly reported to be more accurately recognised; however, there is substantial evidence of increased false alarm rates (FAR) for emotional material and several reports of stronger influences on response bias than accuracy. This pattern is more frequently reported for words than pictures. Research on the mechanisms underlying bias differences has mostly focused on word lists under short retention intervals. This article presents four series of experiments examining recognition memory for emotional pictures while varying arousal and the control over the content of the pictures at two retention intervals, and one study measuring the relatedness of the series picture sets. Under the shorter retention interval, emotion increased false alarms and reduced accuracy. Under the longer retention interval emotion increased hit rates and FAR, resulting in reduced accuracy and/or bias. At both retention intervals, the pattern of valence effects differed based on the arousal associated with the picture sets. Emotional pictures were found to be more related than neutral pictures in each set; however, the influence of relatedness alone does not provide an adequate explanation for all emotional differences. The results demonstrate substantial emotional differences in picture recognition that vary based on valence, arousal and retention interval.

Contrasting landform perception with varied radar illumination geometries and at simulated resolutions of Venera and Magellan

NASA Technical Reports Server (NTRS)

Ford, J. P.; Arvidson, R. E.

1989-01-01

The high sensitivity of imaging radars to slope at moderate to low incidence angles enhances the perception of linear topography on images. It reveals broad spatial patterns that are essential to landform mapping and interpretation. As radar responses are strongly directional, the ability to discriminate linear features on images varies with their orientation. Landforms that appear prominent on images where they are transverse to the illumination may be obscure to indistinguishable on images where they are parallel to it. Landform detection is also influenced by the spatial resolution in radar images. Seasat radar images of the Gran Desierto Dunes complex, Sonora, Mexico; the Appalachian Valley and Ridge Province; and accreted terranes in eastern interior Alaska were processed to simulate both Venera 15 and 16 images (1000 to 3000 km resolution) and image data expected from the Magellan mission (120 to 300 m resolution. The Gran Desierto Dunes are not discernable in the Venera simulation, whereas the higher resolution Magellan simulation shows dominant dune patterns produced from differential erosion of the rocks. The Magellan simulation also shows that fluvial processes have dominated erosion and exposure of the folds.

Comparative Glycoprofiling of HIV gp120 Immunogens by Capillary Electrophoresis and MALDI Mass Spectrometry

PubMed Central

Guttman, Miklós; Váradi, Csaba; Lee, Kelly K.; Guttman, András

2015-01-01

The Human Immunodeficiency Virus (HIV) envelope glycoprotein (Env) is the primary antigenic feature on the surface of the virus and is of key importance in HIV vaccinology. Vaccine trials with the gp120 subunit of Env are ongoing with the recent RV144 trial showing moderate efficacy. gp120 is densely covered with N-linked glycans that are thought to help evade the host's humoral immune response. To assess how the global glycosylation patterns vary between gp120 constructs, the glycan profiles of several gp120s were examined by capillary electrophoresis with laser induced fluorescence detection and MALDI-MS. The glycosylation profiles were found to be similar for chronic vs. transmitter/founder isolates and only varied moderately between gp120s from different clades. This study revealed that the addition of specific tags, such as the gD tag used in the RV144 trial, had significant effects on the overall glycosylation patterns. Such effects are likely to influence the immunogenicity of various Env immunogens and should be considered for future vaccine strategies, emphasizing the importance of the glycosylation analysis approach described in this paper. PMID:25809283

Genome-wide transcriptome analysis of soybean primary root under varying water-deficit conditions.

PubMed

Song, Li; Prince, Silvas; Valliyodan, Babu; Joshi, Trupti; Maldonado dos Santos, Joao V; Wang, Jiaojiao; Lin, Li; Wan, Jinrong; Wang, Yongqin; Xu, Dong; Nguyen, Henry T

2016-01-15

Soybean is a major crop that provides an important source of protein and oil to humans and animals, but its production can be dramatically decreased by the occurrence of drought stress. Soybeans can survive drought stress if there is a robust and deep root system at the early vegetative growth stage. However, little is known about the genome-wide molecular mechanisms contributing to soybean root system architecture. This study was performed to gain knowledge on transcriptome changes and related molecular mechanisms contributing to soybean root development under water limited conditions. The soybean Williams 82 genotype was subjected to very mild stress (VMS), mild stress (MS) and severe stress (SS) conditions, as well as recovery from the severe stress after re-watering (SR). In total, 6,609 genes in the roots showed differential expression patterns in response to different water-deficit stress levels. Genes involved in hormone (Auxin/Ethylene), carbohydrate, and cell wall-related metabolism (XTH/lipid/flavonoids/lignin) pathways were differentially regulated in the soybean root system. Several transcription factors (TFs) regulating root growth and responses under varying water-deficit conditions were identified and the expression patterns of six TFs were found to be common across the stress levels. Further analysis on the whole plant level led to the finding of tissue-specific or water-deficit levels specific regulation of transcription factors. Analysis of the over-represented motif of different gene groups revealed several new cis-elements associated with different levels of water deficit. The expression patterns of 18 genes were confirmed byquantitative reverse transcription polymerase chain reaction method and demonstrated the accuracy and effectiveness of RNA-Seq. The primary root specific transcriptome in soybean can enable a better understanding of the root response to water deficit conditions. The genes detected in root tissues that were associated with key hormones, carbohydrates, and cell wall-related metabolism could play a vital role in achieving drought tolerance and could be promising candidates for future functional characterization. TFs involved in the soybean root and at the whole plant level could be used for future network analysis between TFs and cis-elements. All of these findings will be helpful in elucidating the molecular mechanisms associated with water stress responses in soybean roots.

Modelling survival: exposure pattern, species sensitivity and uncertainty.

PubMed

Ashauer, Roman; Albert, Carlo; Augustine, Starrlight; Cedergreen, Nina; Charles, Sandrine; Ducrot, Virginie; Focks, Andreas; Gabsi, Faten; Gergs, André; Goussen, Benoit; Jager, Tjalling; Kramer, Nynke I; Nyman, Anna-Maija; Poulsen, Veronique; Reichenberger, Stefan; Schäfer, Ralf B; Van den Brink, Paul J; Veltman, Karin; Vogel, Sören; Zimmer, Elke I; Preuss, Thomas G

2016-07-06

The General Unified Threshold model for Survival (GUTS) integrates previously published toxicokinetic-toxicodynamic models and estimates survival with explicitly defined assumptions. Importantly, GUTS accounts for time-variable exposure to the stressor. We performed three studies to test the ability of GUTS to predict survival of aquatic organisms across different pesticide exposure patterns, time scales and species. Firstly, using synthetic data, we identified experimental data requirements which allow for the estimation of all parameters of the GUTS proper model. Secondly, we assessed how well GUTS, calibrated with short-term survival data of Gammarus pulex exposed to four pesticides, can forecast effects of longer-term pulsed exposures. Thirdly, we tested the ability of GUTS to estimate 14-day median effect concentrations of malathion for a range of species and use these estimates to build species sensitivity distributions for different exposure patterns. We find that GUTS adequately predicts survival across exposure patterns that vary over time. When toxicity is assessed for time-variable concentrations species may differ in their responses depending on the exposure profile. This can result in different species sensitivity rankings and safe levels. The interplay of exposure pattern and species sensitivity deserves systematic investigation in order to better understand how organisms respond to stress, including humans.

Modelling survival: exposure pattern, species sensitivity and uncertainty

NASA Astrophysics Data System (ADS)

Ashauer, Roman; Albert, Carlo; Augustine, Starrlight; Cedergreen, Nina; Charles, Sandrine; Ducrot, Virginie; Focks, Andreas; Gabsi, Faten; Gergs, André; Goussen, Benoit; Jager, Tjalling; Kramer, Nynke I.; Nyman, Anna-Maija; Poulsen, Veronique; Reichenberger, Stefan; Schäfer, Ralf B.; van den Brink, Paul J.; Veltman, Karin; Vogel, Sören; Zimmer, Elke I.; Preuss, Thomas G.

2016-07-01

The General Unified Threshold model for Survival (GUTS) integrates previously published toxicokinetic-toxicodynamic models and estimates survival with explicitly defined assumptions. Importantly, GUTS accounts for time-variable exposure to the stressor. We performed three studies to test the ability of GUTS to predict survival of aquatic organisms across different pesticide exposure patterns, time scales and species. Firstly, using synthetic data, we identified experimental data requirements which allow for the estimation of all parameters of the GUTS proper model. Secondly, we assessed how well GUTS, calibrated with short-term survival data of Gammarus pulex exposed to four pesticides, can forecast effects of longer-term pulsed exposures. Thirdly, we tested the ability of GUTS to estimate 14-day median effect concentrations of malathion for a range of species and use these estimates to build species sensitivity distributions for different exposure patterns. We find that GUTS adequately predicts survival across exposure patterns that vary over time. When toxicity is assessed for time-variable concentrations species may differ in their responses depending on the exposure profile. This can result in different species sensitivity rankings and safe levels. The interplay of exposure pattern and species sensitivity deserves systematic investigation in order to better understand how organisms respond to stress, including humans.

Resin Flow Behavior Simulation of Grooved Foam Sandwich Composites with the Vacuum Assisted Resin Infusion (VARI) Molding Process

PubMed Central

Zhao, Chenhui; Zhang, Guangcheng; Wu, Yibo

2012-01-01

The resin flow behavior in the vacuum assisted resin infusion molding process (VARI) of foam sandwich composites was studied by both visualization flow experiments and computer simulation. Both experimental and simulation results show that: the distribution medium (DM) leads to a shorter molding filling time in grooved foam sandwich composites via the VARI process, and the mold filling time is linearly reduced with the increase of the ratio of DM/Preform. Patterns of the resin sources have a significant influence on the resin filling time. The filling time of center source is shorter than that of edge pattern. Point pattern results in longer filling time than of linear source. Short edge/center patterns need a longer time to fill the mould compared with Long edge/center sources.

Shape diagram of vesicles in Poiseuille flow.

PubMed

Coupier, Gwennou; Farutin, Alexander; Minetti, Christophe; Podgorski, Thomas; Misbah, Chaouqi

2012-04-27

Soft bodies flowing in a channel often exhibit parachutelike shapes usually attributed to an increase of hydrodynamic constraint (viscous stress and/or confinement). We show that the presence of a fluid membrane leads to the reverse phenomenon and build a phase diagram of shapes-which are classified as bullet, croissant, and parachute-in channels of varying aspect ratio. Unexpectedly, shapes are relatively wider in the narrowest direction of the channel. We highlight the role of flow patterns on the membrane in this response to the asymmetry of stress distribution.

Modeling spatial effects of PM{sub 2.5} on term low birth weight in Los Angeles County

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

Coker, Eric, E-mail: cokerer@onid.orst.edu; Ghosh, Jokay; Jerrett, Michael

Air pollution epidemiological studies suggest that elevated exposure to fine particulate matter (PM{sub 2.5}) is associated with higher prevalence of term low birth weight (TLBW). Previous studies have generally assumed the exposure–response of PM{sub 2.5} on TLBW to be the same throughout a large geographical area. Health effects related to PM{sub 2.5} exposures, however, may not be uniformly distributed spatially, creating a need for studies that explicitly investigate the spatial distribution of the exposure–response relationship between individual-level exposure to PM{sub 2.5} and TLBW. Here, we examine the overall and spatially varying exposure–response relationship between PM{sub 2.5} and TLBW throughout urbanmore » Los Angeles (LA) County, California. We estimated PM{sub 2.5} from a combination of land use regression (LUR), aerosol optical depth from remote sensing, and atmospheric modeling techniques. Exposures were assigned to LA County individual pregnancies identified from electronic birth certificates between the years 1995-2006 (N=1,359,284) provided by the California Department of Public Health. We used a single pollutant multivariate logistic regression model, with multilevel spatially structured and unstructured random effects set in a Bayesian framework to estimate global and spatially varying pollutant effects on TLBW at the census tract level. Overall, increased PM{sub 2.5} level was associated with higher prevalence of TLBW county-wide. The spatial random effects model, however, demonstrated that the exposure–response for PM{sub 2.5} and TLBW was not uniform across urban LA County. Rather, the magnitude and certainty of the exposure–response estimates for PM{sub 2.5} on log odds of TLBW were greatest in the urban core of Central and Southern LA County census tracts. These results suggest that the effects may be spatially patterned, and that simply estimating global pollutant effects obscures disparities suggested by spatial patterns of effects. Studies that incorporate spatial multilevel modeling with random coefficients allow us to identify areas where air pollutant effects on adverse birth outcomes may be most severe and policies to further reduce air pollution might be most effective. - Highlights: • We model the spatial dependency of PM{sub 2.5} effects on term low birth weight (TLBW). • PM{sub 2.5} effects on TLBW are shown to vary spatially across urban LA County. • Modeling spatial dependency of PM{sub 2.5} health effects may identify effect 'hotspots'. • Birth outcomes studies should consider the spatial dependency of PM{sub 2.5} effects.« less

Modelling effects of diquat under realistic exposure patterns in genetically differentiated populations of the gastropod Lymnaea stagnalis

PubMed Central

Ducrot, Virginie; Péry, Alexandre R. R.; Lagadic, Laurent

2010-01-01

Pesticide use leads to complex exposure and response patterns in non-target aquatic species, so that the analysis of data from standard toxicity tests may result in unrealistic risk forecasts. Developing models that are able to capture such complexity from toxicity test data is thus a crucial issue for pesticide risk assessment. In this study, freshwater snails from two genetically differentiated populations of Lymnaea stagnalis were exposed to repeated acute applications of environmentally realistic concentrations of the herbicide diquat, from the embryo to the adult stage. Hatching rate, embryonic development duration, juvenile mortality, feeding rate and age at first spawning were investigated during both exposure and recovery periods. Effects of diquat on mortality were analysed using a threshold hazard model accounting for time-varying herbicide concentrations. All endpoints were significantly impaired at diquat environmental concentrations in both populations. Snail evolutionary history had no significant impact on their sensitivity and responsiveness to diquat, whereas food acted as a modulating factor of toxicant-induced mortality. The time course of effects was adequately described by the model, which thus appears suitable to analyse long-term effects of complex exposure patterns based upon full life cycle experiment data. Obtained model outputs (e.g. no-effect concentrations) could be directly used for chemical risk assessment. PMID:20921047

Modelling effects of diquat under realistic exposure patterns in genetically differentiated populations of the gastropod Lymnaea stagnalis.

PubMed

Ducrot, Virginie; Péry, Alexandre R R; Lagadic, Laurent

2010-11-12

Pesticide use leads to complex exposure and response patterns in non-target aquatic species, so that the analysis of data from standard toxicity tests may result in unrealistic risk forecasts. Developing models that are able to capture such complexity from toxicity test data is thus a crucial issue for pesticide risk assessment. In this study, freshwater snails from two genetically differentiated populations of Lymnaea stagnalis were exposed to repeated acute applications of environmentally realistic concentrations of the herbicide diquat, from the embryo to the adult stage. Hatching rate, embryonic development duration, juvenile mortality, feeding rate and age at first spawning were investigated during both exposure and recovery periods. Effects of diquat on mortality were analysed using a threshold hazard model accounting for time-varying herbicide concentrations. All endpoints were significantly impaired at diquat environmental concentrations in both populations. Snail evolutionary history had no significant impact on their sensitivity and responsiveness to diquat, whereas food acted as a modulating factor of toxicant-induced mortality. The time course of effects was adequately described by the model, which thus appears suitable to analyse long-term effects of complex exposure patterns based upon full life cycle experiment data. Obtained model outputs (e.g. no-effect concentrations) could be directly used for chemical risk assessment.

Interspecies physiological variation as a tool for cross-species assessments of global warming-induced endangerment: validation of an intrinsic determinant of macroecological and phylogeographic structure.

PubMed

Bernardo, Joseph; Ossola, Ryan J; Spotila, James; Crandall, Keith A

2007-12-22

Global warming is now recognized as the dominant threat to biodiversity because even protected populations and habitats are susceptible. Nonetheless, current criteria for evaluating species' relative endangerment remain purely ecological, and the accepted conservation strategies of habitat preservation and population management assume that species can mount ecological responses if afforded protection. The insidious threat from climate change is that it will attenuate or preclude ecological responses by species that are physiologically constrained; yet, quantitative, objective criteria for assessing relative susceptibility of diverse taxa to warming-induced stress are wanting. We explored the utility of using interspecies physiological variation for this purpose by relating species' physiological phenotypes to landscape patterns of ecological and genetic exchange. Using a salamander model system in which ecological, genetic and physiological diversity are well characterized, we found strong quantitative relationships of basal metabolic rates (BMRs) to both macroecological and phylogeographic patterns, with decreasing BMR leading to dispersal limitation (small contemporary ranges with marked phylogeographic structure). Measures of intrinsic physiological tolerance, which vary systematically with macroecological and phylogeographic patterns, afford objective criteria for assessing endangerment across a wide range of species and should be incorporated into conservation assessment criteria that currently rely exclusively upon ecological predictors.

Gene transcription patterns in response to low level petroleum contaminants in Mytilus trossulus from field sites and harbors in southcentral Alaska

NASA Astrophysics Data System (ADS)

Bowen, Lizabeth; Miles, A. Keith; Ballachey, Brenda; Waters, Shannon; Bodkin, James; Lindeberg, Mandy; Esler, Daniel

2018-01-01

The 1989 Exxon Valdez oil spill damaged a wide range of natural resources, including intertidal communities, and post-spill studies demonstrated acute and chronic exposure and injury to an array of species. Standard toxicological methods to evaluate petroleum contaminants have assessed tissue burdens, with fewer assays providing indicators of health or physiology, particularly when contaminant levels are low and chronic. Marine mussels are a ubiquitous and crucial component of the nearshore environment, and new genomic technologies exist to quantify molecular responses of individual mussels to stimuli, including exposure to polycyclic aromatic hydrocarbons (PAHs). We used gene-based assays of exposure and physiological function to assess chronic oil contamination using the Pacific blue mussel, Mytilus trossulus. We developed a diagnostic gene transcription panel to investigate exposure to PAHs and other contaminants and its effects on mussel physiology and health. During 2012-2015, we analyzed mussels from five field sites in western Prince William Sound, Alaska, with varying oil histories from the 1989 Exxon Valdez oil spill, and from three boat harbors in the area. Gene transcription patterns of mussels from harbors were consistent with elevated exposure to PAHs or other contaminants, whereas transcription patterns of mussels sampled from shorelines in areas affected by the oil spill indicated no PAH exposure.

Microbial Diffraction Gratings as Optical Detectors for Heavy Metal Pollutants

NASA Technical Reports Server (NTRS)

Noever, David; Matsos, Helen; Brittain, Andrew; Obenhuber, Don; Cronise, Raymond; Armstrong, Shannon

1996-01-01

As a significant industrial pollutant, cadmium is implicated as the cause of itai-itai disease. For biological detection of cadmium toxicity, an assay device has been developed using the motile response of the protozoa species, Tetrahymena pyriformis. This mobile protozoa measures 50 microns in diameter, swims at 10 body lengths per second, and aggregates into macroscopically visible patterns at high organism concentrations. The assay demonstrates a Cd(+2) sensitivity better than 1 micro-M and a toxicity threshold to 5 micro-M, thus encouraging the study of these microbial cultures as viable pollution detectors. Using two-dimensional diffraction patterns within a Tetrahymena culture, the scattered light intensity varies with different organism densities (population counts). The resulting density profile correlates strongly with the toxic effects at very low dosages for cadmium (less than 5 ppm) and then for poison protection directly (with nickel and copper antagonists competing with cadmium absorption). In particular, copper dosages as low as 0.1-0.5 mM Cu have shown protective antagonism against cadmium, have enhanced density variability for cultures containing 1 mM Cd(+2) and therefore have demonstrated the sensitivity of the optical detection system. In this way, such microbial diffraction patterns give a responsive optical measure of biological culture changes and toxicity determination in aqueous samples of heavy metals and industrial pollutants.

Linking Plagioclase Zoning Patterns to Active Magma Processes

NASA Astrophysics Data System (ADS)

Izbekov, P. E.; Nicolaysen, K. P.; Neill, O. K.; Shcherbakov, V.; Plechov, P.; Eichelberger, J. C.

2015-12-01

Plagioclase, one of the most common and abundant mineral phases in volcanic products, will vary in composition in response to changes in temperature, pressure, composition of the ambient silicate melt, and melt H2O concentration. Changes in these parameters may cause dissolution or growth of plagioclase crystals, forming characteristic textural and compositional variations (zoning patterns), the complete core-to-rim sequence of which describes events experienced by an individual crystal from its nucleation to the last moments of its growth. Plagioclase crystals in a typical volcanic rock may look drastically dissimilar despite their spatial proximity and the fact that they have erupted together. Although they shared last moments of their growth during magma ascent and eruption, their prior experiences could be very different, as plagioclase crystals often come from different domains of the same magma system. Distinguishing similar zoning patterns, correlating them across the entire population of plagioclase crystals, and linking these patterns to specific perturbations in the magmatic system may provide additional perspective on the variety, extent, and timing of magma processes at active volcanic systems. Examples of magma processes, which may be distinguished based on plagioclase zoning patterns, include (1) cooling due to heat loss, (2) heating and/or pressure build up due to an input of new magmatic material, (3) pressure drop in response to magma system depressurization, and (4) crystal transfer between different magma domains/bodies. This review will include contrasting examples of zoning patters from recent eruptions of Karymsky, Bezymianny, and Tolbachik Volcanoes in Kamchatka, Augustine and Cleveland Volcanoes in Alaska, as well as from the drilling into an active magma body at Krafla, Iceland.

The Differentiation of Response Numerosities in the Pigeon

PubMed Central

Machado, Armando; Rodrigues, Paulo

2007-01-01

Two experiments examined how pigeons differentiate response patterns along the dimension of number. In Experiment 1, 5 pigeons received food after pecking the left key at least N times and then switching to the right key (Mechner’s Fixed Consecutive Number schedule). Parameter N varied across conditions from 4 to 32. Results showed that run length on the left key followed a normal distribution whose mean and standard deviation increased linearly with N; the coefficient of variation approached a constant value (the scalar property). In Experiment 2, 4 pigeons received food with probability p for pecking the left key exactly four times and then switching. If that did not happen, the pigeons still could receive food by returning to the left key and pecking it for a total of at least 16 times and then switching. Parameter p varied across conditions from 1.0 to .25. Results showed that when p = 1.0 or p = .5, pigeons learned two response numerosities within the same condition. When p = .25, each pigeon adapted to the schedule differently. Two of them emitted first runs well described by a mixture of two normal distributions, one with mean close to 4 and the other with mean close to 16 pecks. A mathematical model for the differentiation of response numerosity in Fixed Consecutive Number schedules is proposed. PMID:17970413

Orientation selective deep brain stimulation

NASA Astrophysics Data System (ADS)

Lehto, Lauri J.; Slopsema, Julia P.; Johnson, Matthew D.; Shatillo, Artem; Teplitzky, Benjamin A.; Utecht, Lynn; Adriany, Gregor; Mangia, Silvia; Sierra, Alejandra; Low, Walter C.; Gröhn, Olli; Michaeli, Shalom

2017-02-01

Objective. Target selectivity of deep brain stimulation (DBS) therapy is critical, as the precise locus and pattern of the stimulation dictates the degree to which desired treatment responses are achieved and adverse side effects are avoided. There is a clear clinical need to improve DBS technology beyond currently available stimulation steering and shaping approaches. We introduce orientation selective neural stimulation as a concept to increase the specificity of target selection in DBS. Approach. This concept, which involves orienting the electric field along an axonal pathway, was tested in the corpus callosum of the rat brain by freely controlling the direction of the electric field on a plane using a three-electrode bundle, and monitoring the response of the neurons using functional magnetic resonance imaging (fMRI). Computational models were developed to further analyze axonal excitability for varied electric field orientation. Main results. Our results demonstrated that the strongest fMRI response was observed when the electric field was oriented parallel to the axons, while almost no response was detected with the perpendicular orientation of the electric field relative to the primary fiber tract. These results were confirmed by computational models of the experimental paradigm quantifying the activation of radially distributed axons while varying the primary direction of the electric field. Significance. The described strategies identify a new course for selective neuromodulation paradigms in DBS based on axonal fiber orientation.

The Cardiopulmonary Effects of Ambient Air Pollution and Mechanistic Pathways: A Comparative Hierarchical Pathway Analysis

PubMed Central

Thomas, Duncan C.; Zhang, Junfeng; Kipen, Howard M.; Rich, David Q.; Zhu, Tong; Huang, Wei; Hu, Min; Wang, Guangfa; Wang, Yuedan; Zhu, Ping; Lu, Shou-En; Ohman-Strickland, Pamela; Diehl, Scott R.; Eckel, Sandrah P.

2014-01-01

Previous studies have investigated the associations between exposure to ambient air pollution and biomarkers of physiological pathways, yet little has been done on the comparison across biomarkers of different pathways to establish the temporal pattern of biological response. In the current study, we aim to compare the relative temporal patterns in responses of candidate pathways to different pollutants. Four biomarkers of pulmonary inflammation and oxidative stress, five biomarkers of systemic inflammation and oxidative stress, ten parameters of autonomic function, and three biomarkers of hemostasis were repeatedly measured in 125 young adults, along with daily concentrations of ambient CO, PM2.5, NO2, SO2, EC, OC, and sulfate, before, during, and after the Beijing Olympics. We used a two-stage modeling approach, including Stage I models to estimate the association between each biomarker and pollutant over each of 7 lags, and Stage II mixed-effect models to describe temporal patterns in the associations when grouping the biomarkers into the four physiological pathways. Our results show that candidate pathway groupings of biomarkers explained a significant amount of variation in the associations for each pollutant, and the temporal patterns of the biomarker-pollutant-lag associations varied across candidate pathways (p<0.0001) and were not linear (from lag 0 to lag 3: p = 0.0629, from lag 3 to lag 6: p = 0.0005). These findings suggest that, among this healthy young adult population, the pulmonary inflammation and oxidative stress pathway is the first to respond to ambient air pollution exposure (within 24 hours) and the hemostasis pathway responds gradually over a 2–3 day period. The initial pulmonary response may contribute to the more gradual systemic changes that likely ultimately involve the cardiovascular system. PMID:25502951

Fringe pattern demodulation with a two-dimensional digital phase-locked loop algorithm.

PubMed

Gdeisat, Munther A; Burton, David R; Lalor, Michael J

2002-09-10

A novel technique called a two-dimensional digital phase-locked loop (DPLL) for fringe pattern demodulation is presented. This algorithm is more suitable for demodulation of fringe patterns with varying phase in two directions than the existing DPLL techniques that assume that the phase of the fringe patterns varies only in one direction. The two-dimensional DPLL technique assumes that the phase of a fringe pattern is continuous in both directions and takes advantage of the phase continuity; consequently, the algorithm has better noise performance than the existing DPLL schemes. The two-dimensional DPLL algorithm is also suitable for demodulation of fringe patterns with low sampling rates, and it outperforms the Fourier fringe analysis technique in this aspect.

M.I.T./Canadian vestibular experiments on the Spacelab-1 mission. I - Sensory adaptation to weightlessness and readaptation to one-g: An overview

NASA Technical Reports Server (NTRS)

Young, L. R.; Oman, C. M.; Lichtenberg, B. K.; Watt, D. G. D.; Money, K. E.

1986-01-01

Human sensory/motor adaptation to weightlessness and readaptation to earth's gravity are assessed. Preflight and postflight vestibular and visual responses for the crew on the Spacelab-1 mission are studied; the effect of the abnormal pattern of otolith afferent signals caused by weightlessness on the pitch and roll perception and postural adjustments of the subjects are examined. It is observed that body position and postural reactions change due to weightlessness in order to utilize the varied sensory inputs in a manner suited to microgravity conditions. The aspects of reinterpretation include: (1) tilt acceleration reinterpretation, (2) reduced postural response to z-axis linear acceleration, and (3) increased attention to visual cues.

Hypoxia Stress Modifies Na+/K+-ATPase, H+/K+-ATPase, Na+/NH4+-ATPase, and nkaα1 Isoform Expression in the Brain of Immune-Challenged Air-Breathing Fish

PubMed Central

Peter, MC Subhash; Simi, Satheesan

2017-01-01

Fishes are equipped to sense stressful stimuli and are able to respond to environmental stressor such as hypoxia with varying pattern of stress response. The functional attributes of brain to hypoxia stress in relation to ion transport and its interaction during immune challenge have not yet delineated in fish. We, therefore, explored the pattern of ion transporter functions and messenger RNA (mRNA) expression of α1-subunit isoforms of Na+/K+-ATPase (NKA) in the brain segments, namely, prosencephalon (PC), mesencephalon (MC), and metencephalon (MeC) in an obligate air-breathing fish exposed either to hypoxia stress (30 minutes forced immersion in water) or challenged with zymosan treatment (25-200 ng g−1 for 24 hours) or both. Zymosan that produced nonspecific immune responses evoked differential regulation of NKA, H+/K+-ATPase (HKA), and Na+/NH4+-ATPase (NNA) in the varied brain segments. On the contrary, hypoxia stress that demanded activation of NKA in PC and MeC showed a reversed NKA activity pattern in MeC of immune-challenged fish. A compromised HKA and NNA regulation during hypoxia stress was found in immune-challenged fish, indicating the role of these brain ion transporters to hypoxia stress and immune challenges. The differential mRNA expression of α1-subunit isoforms of NKA, nkaα1a, nkaα1b, and nkaα1c, in hypoxia-stressed brain showed a shift in its expression pattern during hypoxia stress-immune interaction in PC and MC. Evidence is thus presented for the first time that ion transporters such as HKA and NNA along with NKA act as functional brain markers which respond differentially to both hypoxia stress and immune challenges. Taken together, the data further provide evidence for a differential Na+, K+, H+, and NH4+ ion signaling that exists in brain neuronal clusters during hypoxia stress-immune interaction as a result of modified regulations of NKA, HKA, and NNA transporter functions and nkaα1 isoform regulation. PMID:29238219

Hypoxia Stress Modifies Na+/K+-ATPase, H+/K+-ATPase, [Formula: see text], and nkaα1 Isoform Expression in the Brain of Immune-Challenged Air-Breathing Fish.

PubMed

Peter, Mc Subhash; Simi, Satheesan

2017-01-01

Fishes are equipped to sense stressful stimuli and are able to respond to environmental stressor such as hypoxia with varying pattern of stress response. The functional attributes of brain to hypoxia stress in relation to ion transport and its interaction during immune challenge have not yet delineated in fish. We, therefore, explored the pattern of ion transporter functions and messenger RNA (mRNA) expression of α1-subunit isoforms of Na + /K + -ATPase (NKA) in the brain segments, namely, prosencephalon (PC), mesencephalon (MC), and metencephalon (MeC) in an obligate air-breathing fish exposed either to hypoxia stress (30 minutes forced immersion in water) or challenged with zymosan treatment (25-200 ng g -1 for 24 hours) or both. Zymosan that produced nonspecific immune responses evoked differential regulation of NKA, H + /K + -ATPase (HKA), and [Formula: see text] (NNA) in the varied brain segments. On the contrary, hypoxia stress that demanded activation of NKA in PC and MeC showed a reversed NKA activity pattern in MeC of immune-challenged fish. A compromised HKA and NNA regulation during hypoxia stress was found in immune-challenged fish, indicating the role of these brain ion transporters to hypoxia stress and immune challenges. The differential mRNA expression of α1-subunit isoforms of NKA, nkaα1a , nkaα1b , and nkaα1c , in hypoxia-stressed brain showed a shift in its expression pattern during hypoxia stress-immune interaction in PC and MC. Evidence is thus presented for the first time that ion transporters such as HKA and NNA along with NKA act as functional brain markers which respond differentially to both hypoxia stress and immune challenges. Taken together, the data further provide evidence for a differential Na + , K + , H + , and [Formula: see text] ion signaling that exists in brain neuronal clusters during hypoxia stress-immune interaction as a result of modified regulations of NKA, HKA, and NNA transporter functions and nkaα1 isoform regulation.

The Cluster Variation Method: A Primer for Neuroscientists.

PubMed

Maren, Alianna J

2016-09-30

Effective Brain-Computer Interfaces (BCIs) require that the time-varying activation patterns of 2-D neural ensembles be modelled. The cluster variation method (CVM) offers a means for the characterization of 2-D local pattern distributions. This paper provides neuroscientists and BCI researchers with a CVM tutorial that will help them to understand how the CVM statistical thermodynamics formulation can model 2-D pattern distributions expressing structural and functional dynamics in the brain. The premise is that local-in-time free energy minimization works alongside neural connectivity adaptation, supporting the development and stabilization of consistent stimulus-specific responsive activation patterns. The equilibrium distribution of local patterns, or configuration variables , is defined in terms of a single interaction enthalpy parameter ( h ) for the case of an equiprobable distribution of bistate (neural/neural ensemble) units. Thus, either one enthalpy parameter (or two, for the case of non-equiprobable distribution) yields equilibrium configuration variable values. Modeling 2-D neural activation distribution patterns with the representational layer of a computational engine, we can thus correlate variational free energy minimization with specific configuration variable distributions. The CVM triplet configuration variables also map well to the notion of a M = 3 functional motif. This paper addresses the special case of an equiprobable unit distribution, for which an analytic solution can be found.

The Cluster Variation Method: A Primer for Neuroscientists

PubMed Central

Maren, Alianna J.

2016-01-01

Effective Brain–Computer Interfaces (BCIs) require that the time-varying activation patterns of 2-D neural ensembles be modelled. The cluster variation method (CVM) offers a means for the characterization of 2-D local pattern distributions. This paper provides neuroscientists and BCI researchers with a CVM tutorial that will help them to understand how the CVM statistical thermodynamics formulation can model 2-D pattern distributions expressing structural and functional dynamics in the brain. The premise is that local-in-time free energy minimization works alongside neural connectivity adaptation, supporting the development and stabilization of consistent stimulus-specific responsive activation patterns. The equilibrium distribution of local patterns, or configuration variables, is defined in terms of a single interaction enthalpy parameter (h) for the case of an equiprobable distribution of bistate (neural/neural ensemble) units. Thus, either one enthalpy parameter (or two, for the case of non-equiprobable distribution) yields equilibrium configuration variable values. Modeling 2-D neural activation distribution patterns with the representational layer of a computational engine, we can thus correlate variational free energy minimization with specific configuration variable distributions. The CVM triplet configuration variables also map well to the notion of a M = 3 functional motif. This paper addresses the special case of an equiprobable unit distribution, for which an analytic solution can be found. PMID:27706022

Patterns of oribatid mite species diversity: testing the effects of elevation, area and sampling effort.

PubMed

Mumladze, Levan; Murvanidze, Maka; Maraun, Mark

2017-07-01

Elevational gradients in species diversity and species area relationships are two well established patterns that are not mutually exclusive in space and time. Elevation and area are both considered as good proxies to detect and characterize the patterns of species diversity distribution. However, such studies are hampered by the incomplete biodiversity data available for ecologists, which may affect the pattern perceptions. Using the large dataset of oribatid mite communities sampled in Georgia, we tested the effects of altitude and area on species distribution using various approaches, while explicitly considering the biases from sampling effort. Our results showed that elevation and area are strongly correlated (with increasing absolute elevation, land area decreases) and both have strong linear effects on species diversity distribution when studied separately. Approaches based on multiple regression and direct removal of co-varied factors, indicated that the effect of area can actually override the effect of elevation in describing the oribatid species diversity distribution along with elevation. On the other hand, the bias of sampling proved significant in perception of elevational species richness pattern with less effect on elevational species area relationship. We suggest that the sampling alone may be responsible for patterns observed and thus should be considered in ecological studies when eligible.

Inhibitory Processes in Young Children and Individual Variation in Short-Term Memory

PubMed Central

Espy, Kimberly Andrews; Bull, Rebecca

2009-01-01

A precise definition of executive control remains elusive, related in part to the variations among executive tasks in the nature of the task demands, which complicate the identification of test-specific versus construct-specific performance. In this study, tasks were chosen that varied in the nature of the stimulus (verbal, nonverbal), response (naming, somatic motor), conflict type (proactive interference, distraction), and inhibitory process (attention control, response suppression) required. Then performance differences were examined in 184 young children (age range = 3 years 6 months to 6 years 1 month), comparing those with high (5 or more digits) and low (3 or fewer digits) spans to determine the dependence on short-term memory. Results indicated that there was communality in inhibitory task demands across instruments, although the specific pattern of task intercorrelations varied in children with high and low spans. Furthermore, only performance on attention control tasks—that is, that require cognitive engagement/disengagement among an internally represented rule or response set that was previously active versus those currently active—differed between children of high and low spans. In contrast, there were differences neither between children with high and low spans on response suppression tasks nor on tasks when considered by type of stimulus, response, or conflict. Individual differences in well-regulated thought may rest in variations in the ability to maintain information in an active, quickly retrievable state that subserve controlling attention in a goal-relevant fashion. PMID:16144432

A qualitative study of diverse providers' behaviour in response to commissioners, patients and innovators in England: research protocol.

PubMed

Sheaff, Rod; Halliday, Joyce; Exworthy, Mark; Allen, Pauline; Mannion, Russell; Asthana, Sheena; Gibson, Alex; Clark, Jonathan

2016-05-13

The variety of organisations providing National Health Service (NHS)-funded services in England is growing. Besides NHS hospitals and general practitioners (GPs), they include corporations, social enterprises, voluntary organisations and others. The degree to which these organisational types vary, however, in the ways they manage and provide services and in the outcomes for service quality, patient experience and innovation, remains unclear. This research will help those who commission NHS services select among the different types of organisation for different tasks. The main research questions are how organisationally diverse NHS-funded service providers vary in their responsiveness to patient choice, NHS commissioning and policy changes; and their patterns of innovation. We aim to assess the implications for NHS commissioning and managerial practice which follow from these differences. Systematic qualitative comparison across a purposive sample (c.12) of providers selected for maximum variety of organisational type, with qualitative studies of patient experience and choice (in the same sites). We focus is on NHS services heavily used by older people at high risk of hospital admission: community health services; out-of-hours primary care; and secondary care (planned orthopaedics or ophthalmology). The expected outputs will be evidence-based schemas showing how patterns of service development and delivery typically vary between different organisational types of provider. We will ensure informants' organisational and individual anonymity when dealing with high profile case studies and a competitive health economy. The frail elderly is a key demographic sector with significant policy and financial implications. For NHS commissioners, patients, doctors and other stakeholders, the main outcome will be better knowledge about the relative merits of different kinds of healthcare provider. Dissemination will make use of strategies suggested by patient and public involvement, as well as DH and service-specific outlets. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Patterns in Elementary School Students' Strategic Actions in Varying Learning Situations

ERIC Educational Resources Information Center

Malmberg, Jonna; Järvenoja, Hanna; Järvelä, Sanna

2013-01-01

This study uses log file traces to examine differences between high-and low-achieving students' strategic actions in varying learning situations. In addition, this study illustrates, in detail, what strategic and self-regulated learning constitutes in practice. The study investigates the learning patterns that emerge in learning situations…

The Ecohydrologic Role of Coexistence and Competition in Semiarid Hillslopes

NASA Astrophysics Data System (ADS)

Soltanjalili, M. J.; Saco, P. M.; Willgoose, G. R.

2015-12-01

Through its influence on runoff and erosion-deposition processes, vegetation remarkably regulates different aspects of landscape dynamics. Here, the influence of different plant functional traits on the coexistence of different species in arid and semi-arid regions with patchy vegetation is investigated using an ecohydrology model. The model simulates coevolving changes in biomass patterns for two species, as well as overland flow and soil moisture dynamics. Vegetation patterns emerge as a result of facilitation (shading and infiltration) and competition mechanisms as well as varying seed dispersal strategies. The results show that the survival of only one species or the coexistence of both species not only strongly depends on environmental stresses, but also on differences in hillslope micro and macro topography. These vegetation patterns have very different hydrologic signatures and the potential to trigger remarkably different geomorphic responses. Based on these results we establish new hypothesis that will be used to further investigate the role of plant interspecific and intraspecific feedbacks on landscape coevolution processes.

Large dynamic range digital nanodot gradients of biomolecules made by low-cost nanocontact printing for cell haptotaxis.

PubMed

Ricoult, Sébastien G; Pla-Roca, Mateu; Safavieh, Roozbeh; Lopez-Ayon, G Monserratt; Grütter, Peter; Kennedy, Timothy E; Juncker, David

2013-10-11

A novel method is introduced for ultrahigh throughput and ultralow cost patterning of biomolecules with nanometer resolution and novel 2D digital nanodot gradients (DNGs) with mathematically defined slopes are created. The technique is based on lift-off nanocontact printing while using high-resolution photopolymer stamps that are rapidly produced at a low cost through double replication from Si originals. Printed patterns with 100 nm features are shown. DNGs with varying spacing between the dots and a record dynamic range of 4400 are produced; 64 unique DNGs, each with hundreds of thousands of dots, are inked and printed in 5.5 min. The adhesive response and haptotaxis of C2C12 myoblast cells on DNGs demonstrated their biofunctionality. The great flexibility in pattern design, the massive parallel ability, the ultra low cost, and the extreme ease of polymer lift-off nanocontact printing will facilitate its use for various biological and medical applications. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Modeling patterns of coral bleaching at a remote Central Pacific atoll.

PubMed

Williams, Gareth J; Knapp, Ingrid S; Maragos, James E; Davy, Simon K

2010-09-01

A mild bleaching event (9.2% prevalence) at Palmyra Atoll occurred in response to the 2009 ENSO, when mean water temperature reached 29.8-30.1 degrees C. Prevalence among both abundant and sparse taxa varied with no clear pattern in susceptibility relating to coral morphology. Seven taxon-specific models showed that turbidity exacerbated while prior exposure to higher background temperatures alleviated bleaching, with these predictors explaining an average 16.3% and 11.5% variation in prevalence patterns, respectively. Positive associations occurred between bleaching prevalence and both immediate temperature during the bleaching event (average 8.4% variation explained) and increased sand cover (average 3.7%). Despite these associations, mean unexplained variation in prevalence equalled 59%. Lower bleaching prevalence in areas experiencing higher background temperatures suggests acclimation to temperature stress among several coral genera, while WWII modifications may still be impacting the reefs via shoreline sediment re-distribution and increased turbidity, exacerbating coral bleaching susceptibility during periods of high temperature stress. Copyright 2010 Elsevier Ltd. All rights reserved.

Fluctuating interaction network and time-varying stability of a natural fish community

NASA Astrophysics Data System (ADS)

Ushio, Masayuki; Hsieh, Chih-Hao; Masuda, Reiji; Deyle, Ethan R.; Ye, Hao; Chang, Chun-Wei; Sugihara, George; Kondoh, Michio

2018-02-01

Ecological theory suggests that large-scale patterns such as community stability can be influenced by changes in interspecific interactions that arise from the behavioural and/or physiological responses of individual species varying over time. Although this theory has experimental support, evidence from natural ecosystems is lacking owing to the challenges of tracking rapid changes in interspecific interactions (known to occur on timescales much shorter than a generation time) and then identifying the effect of such changes on large-scale community dynamics. Here, using tools for analysing nonlinear time series and a 12-year-long dataset of fortnightly collected observations on a natural marine fish community in Maizuru Bay, Japan, we show that short-term changes in interaction networks influence overall community dynamics. Among the 15 dominant species, we identify 14 interspecific interactions to construct a dynamic interaction network. We show that the strengths, and even types, of interactions change with time; we also develop a time-varying stability measure based on local Lyapunov stability for attractor dynamics in non-equilibrium nonlinear systems. We use this dynamic stability measure to examine the link between the time-varying interaction network and community stability. We find seasonal patterns in dynamic stability for this fish community that broadly support expectations of current ecological theory. Specifically, the dominance of weak interactions and higher species diversity during summer months are associated with higher dynamic stability and smaller population fluctuations. We suggest that interspecific interactions, community network structure and community stability are dynamic properties, and that linking fluctuating interaction networks to community-level dynamic properties is key to understanding the maintenance of ecological communities in nature.

[Growth characteristics of Porites lutea skeleton in east sea area of Hainan Island, China and main affecting environmental factors.

PubMed

Jiang, Qiao Wen; Cao, Zhi Min; Wang, Dao Ru; Li, Yuan Chao; Ni, Jian Yu

2016-03-01

The growth characteristics of Porites lutea skeleton in east sea area of Hainan Island were studied by CoralXDS software based on X-ray chronology. The growth parameters obtained included extension rate (ER), skeleton density (D), and calcification rate (CR). The results showed that ER varied from 0.49 to 1.10 cm·a -1 with an annual average of 0.76 cm·a -1 , D varied from 1.11 to 1.35 g·cm -3 with an annual average of 1.22 g·cm -3 , and CR varied from 0.55 to 1.41 g·cm -2 ·a -1 with an annual average of 0.94 g·cm -2 ·a -1 . Statistical analyses indicated that sea surface temperature (SST) was the key environmental factor that controlled the growth characteristics, as it highly co-varied with ER and CR, less so with D. All of the three growth characteristics increased with the increase of SST. There were other factors that influenced the growth characteristics of the coral column, such as light, water salinity, and hydrodynamics, etc. In addition, typhoon and severe tropical storms also imposed a significant impact on the growth pattern of Porites lutea coral. The change in growth pattern of coral skeleton in east of Hainan Island was a response to complex climate fluctuation. Over the past century, SST of east Hainan Island dramatically increased at a rate of 0.15 ℃·(10 a) -1 . The SST increase trend for the oceanic region could be divided into two stages, early 1940s and early 1980s. The human activities and global warming was the main causes for the increase of SST.

Symptom clusters at midlife: A four-country comparison of checklist and qualitative responses

PubMed Central

Sievert, Lynnette Leidy; Obermeyer, Carla Makhlouf

2011-01-01

Objectives The purpose of this study was to examine the frequency and clustering of somatic symptoms as reported by women aged 45-55 years in four countries, to compare women's responses to open-ended questions with those derived from structured checklists, and to assess the extent to which bodily symptoms grouped with emotional complaints. Methods The Decisions at Menopause Study (DAMES) recruited 1,193 women from the general population in Beirut, Lebanon; Rabat, Morocco; Madrid, Spain; and central Massachusetts. Women participated in semi-structured interviews about health, menopause, and bodily changes at midlife. Women's responses to symptom checklists and their statements in response to open-ended questions were analyzed through factor analysis and textual analysis. Results There was considerable consistency between the frequencies of quantitative and qualitative responses, and the analyses of qualitative data illustrate the extent to which women associate somatic and emotional complaints. In open-ended responses, women in Massachusetts and Spain did not often cluster somatic symptoms together with emotional symptoms. In Morocco, dizziness, fatigue, and headaches were clustered with emotional symptoms. Women in Lebanon explicitly associated shortness of breath, chest pain, palpitations, dizziness, fatigue, gastro-intestinal complaints, headaches, and, to a lesser extent, joint pain and numbness with emotional symptoms. Conclusions The number of volunteered symptom responses was small because respondents were relatively healthy; however, the extent and pattern of association between somatic and emotional symptoms varied across sites. Certain somatic symptoms may be more likely to communicate psychosocial distress in particular cultures. These results have implications for patterns of health care utilization. PMID:22042326

The Rise and Fall of Priming: How Visual Exposure Shapes Cortical Representations of Objects

PubMed Central

Zago, Laure; Fenske, Mark J.; Aminoff, Elissa; Bar, Moshe

2006-01-01

How does the amount of time for which we see an object influence the nature and content of its cortical representation? To address this question, we varied the duration of initial exposure to visual objects and then measured functional magnetic resonance imaging (fMRI) signal and behavioral performance during a subsequent repeated presentation of these objects. We report a novel ‘rise-and-fall’ pattern relating exposure duration and the corresponding magnitude of fMRI cortical signal. Compared with novel objects, repeated objects elicited maximal cortical response reduction when initially presented for 250 ms. Counter-intuitively, initially seeing an object for a longer duration significantly reduced the magnitude of this effect. This ‘rise-and-fall’ pattern was also evident for the corresponding behavioral priming. To account for these findings, we propose that the earlier interval of an exposure to a visual stimulus results in a fine-tuning of the cortical response, while additional exposure promotes selection of a subset of key features for continued representation. These two independent mechanisms complement each other in shaping object representations with experience. PMID:15716471

Personas in online health communities.

PubMed

Huh, Jina; Kwon, Bum Chul; Kim, Sung-Hee; Lee, Sukwon; Choo, Jaegul; Kim, Jihoon; Choi, Min-Je; Yi, Ji Soo

2016-10-01

Many researchers and practitioners use online health communities (OHCs) to influence health behavior and provide patients with social support. One of the biggest challenges in this approach, however, is the rate of attrition. OHCs face similar problems as other social media platforms where user migration happens unless tailored content and appropriate socialization is supported. To provide tailored support for each OHC user, we developed personas in OHCs illustrating users' needs and requirements in OHC use. To develop OHC personas, we first interviewed 16 OHC users and administrators to qualitatively understand varying user needs in OHC. Based on their responses, we developed an online survey to systematically investigate OHC personas. We received 184 survey responses from OHC users, which informed their values and their OHC use patterns. We performed open coding analysis with the interview data and cluster analysis with the survey data and consolidated the analyses of the two datasets. Four personas emerged-Caretakers, Opportunists, Scientists, and Adventurers. The results inform users' interaction behavior and attitude patterns with OHCs. We discuss implications for how these personas inform OHCs in delivering personalized informational and emotional support. Copyright © 2016 Elsevier Inc. All rights reserved.

Helicopter pilots' views of air traffic controller responsibilities: a mismatch.

PubMed

Martin, Daniel; Nixon, Jim

2018-02-21

Controllers and pilots must work together to ensure safe and efficient helicopter flight within the London control zone. Subjective ratings of pilot perception of controller responsibility for five key flight tasks were obtained from thirty helicopter pilots. Three types of airspace were investigated. Results indicate that there is variation in pilot understanding of controller responsibility compared to the formal regulations that define controller responsibility. Significant differences in the perception of controller responsibility were found for the task of aircraft separation in class D airspace and along helicopter routes. Analysis of the patterns of response suggests that task type rather than the airspace type may be the key factor. Results are framed using the concept of a shared mental model. This research demonstrates that pilots flying in complex London airspace have an expectation of controller responsibility for certain flight tasks, in certain airspace types that is not supported by aviation regulation. Practitioner Summary: The responsibility for tasks during flight varies according to the flight rules used and airspace type. Helicopter pilots may attribute responsibility to controllers for tasks when controllers have no responsibility as defined by regulation. This variation between pilot perceptions of controller responsibility could affect safety within the London control zone.

Understanding multidecadal variability in ENSO amplitude

NASA Astrophysics Data System (ADS)

Russell, A.; Gnanadesikan, A.

2013-12-01

Sea surface temperatures (SSTs) in the tropical Pacific vary as a result of the coupling between the ocean and atmosphere driven largely by the El Niño - Southern Oscillation (ENSO). ENSO has a large impact on the local climate and hydrology of the tropical Pacific, as well as broad-reaching effects on global climate. ENSO amplitude is known to vary on long timescales, which makes it very difficult to quantify its response to climate change and constrain the physical processes that drive it. In order to assess the extent of unforced multidecadal changes in ENSO variability, a linear regression of local SST changes is applied to the GFDL CM2.1 model 4000-yr pre-industrial control run. The resulting regression coefficient strengths, which represent the sensitivity of SST changes to thermocline depth and zonal wind stress, vary by up to a factor of 2 on multi-decadal time scales. This long-term modulation in ocean-atmosphere coupling is highly correlated with ENSO variability, but do not explain the reasons for such variability. Variation in the relationship between SST changes and wind stress points to a role for changing stratification in the central equatorial Pacific in modulating ENSO amplitudes with stronger stratification reducing the response to winds. The main driving mechanism we have identified for higher ENSO variance are changes in the response of zonal winds to SST anomalies. The shifting convection and precipitation patterns associated with the changing state of the atmosphere also contribute to the variability of the regression coefficients. These mechanisms drive much of the variability in ENSO amplitude and hence ocean-atmosphere coupling in the tropical Pacific.

Single-trial decoding of auditory novelty responses facilitates the detection of residual consciousness

PubMed Central

King, J.R.; Faugeras, F.; Gramfort, A.; Schurger, A.; El Karoui, I.; Sitt, J.D.; Rohaut, B.; Wacongne, C.; Labyt, E.; Bekinschtein, T.; Cohen, L.; Naccache, L.; Dehaene, S.

2017-01-01

Detecting residual consciousness in unresponsive patients is a major clinical concern and a challenge for theoretical neuroscience. To tackle this issue, we recently designed a paradigm that dissociates two electro-encephalographic (EEG) responses to auditory novelty. Whereas a local change in pitch automatically elicits a mismatch negativity (MMN), a change in global sound sequence leads to a late P300b response. The latter component is thought to be present only when subjects consciously perceive the global novelty. Unfortunately, it can be difficult to detect because individual variability is high, especially in clinical recordings. Here, we show that multivariate pattern classifiers can extract subject-specific EEG patterns and predict single-trial local or global novelty responses. We first validate our method with 38 high-density EEG, MEG and intracranial EEG recordings. We empirically demonstrate that our approach circumvents the issues associated with multiple comparisons and individual variability while improving the statistics. Moreover, we confirm in control subjects that local responses are robust to distraction whereas global responses depend on attention. We then investigate 104 vegetative state (VS), minimally conscious state (MCS) and conscious state (CS) patients recorded with high-density EEG. For the local response, the proportion of significant decoding scores (M = 60%) does not vary with the state of consciousness. By contrast, for the global response, only 14% of the VS patients' EEG recordings presented a significant effect, compared to 31% in MCS patients' and 52% in CS patients'. In conclusion, single-trial multivariate decoding of novelty responses provides valuable information in non-communicating patients and paves the way towards real-time monitoring of the state of consciousness. PMID:23859924

Controlled Chemical Patterns with ThermoChemical NanoLithography (TCNL)

NASA Astrophysics Data System (ADS)

Carroll, Keith; Giordano, Anthony; Wang, Debin; Kodali, Vamsi; King, W. P.; Marder, S. R.; Riedo, E.; Curtis, J. E.

2012-02-01

Many research areas, both fundamental and applied, rely upon the ability to organize non-trivial assemblies of molecules on surfaces. In this work, we introduce a significant extension of ThermoChemical NanoLithography (TCNL), a high throughput chemical patterning technique that uses temperature-driven chemical reactions localized near the tip of a thermal cantilever. By combining a chemical kinetics based model with experiments, we have developed a protocol for varying the concentration of surface bound molecules. The result is an unprecedented ability to fabricate extremely complex patterns comprised of varying chemical concentrations, as demonstrated by sinusoidal patterns of amine groups with varying pitches (˜5-15 μm) and the replication of Leonardo da Vinci's Mona Lisa with dimensions of ˜30 x 40 μm^2. Programmed control of the chemical reaction rate should have widespread applications for a technique which has already been shown to nanopattern various substrates including graphene nanowires, piezoelectric crystals, and optoelectronic materials.

The Success Rate of Neurology Residents in EEG Interpretation After Formal Training.

PubMed

Dericioglu, Nese; Ozdemir, Pınar

2018-03-01

EEG is an important tool for neurologists in both diagnosis and classification of seizures. It is not uncommon in clinical practice to see patients who were erroneously diagnosed as epileptic. Most of the time incorrect interpretation of EEG contributes significantly to this problem. In this study, we aimed to investigate the success rate of neurology residents in EEG interpretation after formal training. Eleven neurology residents were included in the study. Duration of EEG training (3 vs 4 months) and time since completion of EEG education were determined. Residents were randomly presented 30 different slides of representative EEG screenshots. They received 1 point for each correct response. The effect of training duration and time since training were investigated statistically. Besides, we looked at the success rate of each question to see whether certain patterns were more readily recognized than others. EEG training duration ( P = .93) and time since completion of training ( P = .16) did not influence the results. The success rate of residents for correct responses was between 17% and 50%. On the other hand, the success rate for each question varied between 0% and 91%. Overall, benign variants and focal ictal onset patterns were the most difficult to recognize. On 13 occasions (6.5%) nonepileptiform patterns were thought to represent epileptiform abnormalities. After formal training, neurology residents could identify ≤50% of the EEG patterns correctly. The wide variation in success rate among residents and also between questions implies that both personal characteristics and inherent EEG features influence successful EEG interpretation.

Expression patterns of WRKY genes in di-haploid Populus simonii × P. nigra in response to salinity stress revealed by quantitative real-time PCR and RNA sequencing.

PubMed

Wang, Shengji; Wang, Jiying; Yao, Wenjing; Zhou, Boru; Li, Renhua; Jiang, Tingbo

2014-10-01

Spatio-temporal expression patterns of 13 out of 119 poplar WRKY genes indicated dynamic and tissue-specific roles of WRKY family proteins in salinity stress tolerance. To understand the expression patterns of poplar WRKY genes under salinity stress, 51 of the 119 WRKY genes were selected from di-haploid Populus simonii × P. nigra by quantitative real-time PCR (qRT-PCR). We used qRT-PCR to profile the expression of the top 13 genes under salinity stress across seven time points, and employed RNA-Seq platforms to cross-validate it. Results demonstrated that all the 13 WRKY genes were expressed in root, stem, and leaf tissues, but their expression levels and overall patterns varied notably in these tissues. Regarding overall gene expression in roots, the 13 genes were significantly highly expressed at all six time points after the treatment, reaching the plateau of expression at hour 9. In leaves, the 13 genes were similarly up-regulated from 3 to 12 h in response to NaCl treatment. In stems, however, expression levels of the 13 genes did not show significant changes after the NaCl treatment. Regarding individual gene expression across the time points and the three tissues, the 13 genes can be classified into three clusters: the lowly expressed Cluster 1 containing PthWRKY28, 45 and 105; intermediately expressed Clusters 2 including PthWRKY56, 88 and 116; and highly expressed Cluster 3 consisting of PthWRKY41, 44, 51, 61, 62, 75 and 106. In general, genes in Cluster 2 and 3 displayed a dynamic pattern of "induced amplification-recovering", suggesting that these WRKY genes and corresponding pathways may play a critical role in mediating salt response and tolerance in a dynamic and tissue-specific manner.

Limited spatial response to direct predation risk by African herbivores following predator reintroduction.

PubMed

Davies, Andrew B; Tambling, Craig J; Kerley, Graham I H; Asner, Gregory P

2016-08-01

Predators affect ecosystems not only through direct mortality of prey, but also through risk effects on prey behavior, which can exert strong influences on ecosystem function and prey fitness. However, how functionally different prey species respond to predation risk and how prey strategies vary across ecosystems and in response to predator reintroduction are poorly understood. We investigated the spatial distributions of six African herbivores varying in foraging strategy and body size in response to environmental factors and direct predation risk by recently reintroduced lions in the thicket biome of the Addo Elephant National Park, South Africa, using camera trap surveys, GPS telemetry, kill site locations and Light Detection and Ranging. Spatial distributions of all species, apart from buffalo, were driven primarily by environmental factors, with limited responses to direct predation risk. Responses to predation risk were instead indirect, with species distributions driven by environmental factors, and diel patterns being particularly pronounced. Grazers were more responsive to the measured variables than browsers, with more observations in open areas. Terrain ruggedness was a stronger predictor of browser distributions than was vegetation density. Buffalo was the only species to respond to predator encounter risk, avoiding areas with higher lion utilization. Buffalo therefore behaved in similar ways to when lions were absent from the study area. Our results suggest that direct predation risk effects are relatively weak when predator densities are low and the time since reintroduction is short and emphasize the need for robust, long-term monitoring of predator reintroductions to place such events in the broader context of predation risk effects.

Distinguishing dose, focus, and blur for lithography characterization and control

NASA Astrophysics Data System (ADS)

Ausschnitt, Christopher P.; Brunner, Timothy A.

2007-03-01

We derive a physical model to describe the dependence of pattern dimensions on dose, defocus and blur. The coefficients of our model are constants of a given lithographic process. Model inversion applied to dimensional measurements then determines effective dose, defocus and blur for wafers patterned with the same process. In practice, our approach entails the measurement of proximate grating targets of differing dose and focus sensitivity. In our embodiment, the measured attribute of one target is exclusively sensitive to dose, whereas the measured attributes of a second target are distinctly sensitive to defocus and blur. On step-and-scan exposure tools, z-blur is varied in a controlled manner by adjusting the across slit tilt of the image plane. The effects of z-blur and x,y-blur are shown to be equivalent. Furthermore, the exposure slit width is shown to determine the tilt response of the grating attributes. Thus, the response of the measured attributes can be characterized by a conventional focus-exposure matrix (FEM), over which the exposure tool settings are intentionally changed. The model coefficients are determined by a fit to the measured FEM response. The model then fully defines the response for wafers processed under "fixed" dose, focus and blur conditions. Model inversion applied to measurements from the same targets on all such wafers enables the simultaneous determination of effective dose and focus/tilt (DaFT) at each measurement site.

Potential coastal impacts of contemporary changing climate on South Asian seas states

NASA Astrophysics Data System (ADS)

Gable, F. J.; Aubrey, D. G.

1990-01-01

The threat of man-induced global change on the nations of the South Asian seas region varies from place to place because of differences in exposure to monsoons and stoms, differences in local tectonics and subsidence, and variations in air and sea climates. Because several nations are involved, some having subsistence budgets, and given the cost of deriving independently a comprehensive response to global change, the similarities and differences between national settings must be identified soon. These comparisons will form the basis for local response strategies: the similarities provide a basis for responses similar to that of other nations and the differences provide for local adaptation. That climate change on the South Asian coastal region will have an impact is certain: its economics, environment, and coastal land uses are dominated to a certain extent by this marine influence. The extent of these impacts, however, is uncertain. Accompanying global change will be changes in sea level, differences in storm climate, and altered precipitation patterns; science cannot define today what pattern these changes will take. Because global change is inevitable—although its magnitude, timing, and geographic distribution are unknown—the South Asian seas region should begin the appropriate research and planning studies to set forth a reasoned response to global change, for implementation when scientific evidence for global change is more quantitative.

Statistical analysis of hydrological response in urbanising catchments based on adaptive sampling using inter-amount times

NASA Astrophysics Data System (ADS)

ten Veldhuis, Marie-Claire; Schleiss, Marc

2017-04-01

Urban catchments are typically characterised by a more flashy nature of the hydrological response compared to natural catchments. Predicting flow changes associated with urbanisation is not straightforward, as they are influenced by interactions between impervious cover, basin size, drainage connectivity and stormwater management infrastructure. In this study, we present an alternative approach to statistical analysis of hydrological response variability and basin flashiness, based on the distribution of inter-amount times. We analyse inter-amount time distributions of high-resolution streamflow time series for 17 (semi-)urbanised basins in North Carolina, USA, ranging from 13 to 238 km2 in size. We show that in the inter-amount-time framework, sampling frequency is tuned to the local variability of the flow pattern, resulting in a different representation and weighting of high and low flow periods in the statistical distribution. This leads to important differences in the way the distribution quantiles, mean, coefficient of variation and skewness vary across scales and results in lower mean intermittency and improved scaling. Moreover, we show that inter-amount-time distributions can be used to detect regulation effects on flow patterns, identify critical sampling scales and characterise flashiness of hydrological response. The possibility to use both the classical approach and the inter-amount-time framework to identify minimum observable scales and analyse flow data opens up interesting areas for future research.

Baby schema in human and animal faces induces cuteness perception and gaze allocation in children.

PubMed

Borgi, Marta; Cogliati-Dezza, Irene; Brelsford, Victoria; Meints, Kerstin; Cirulli, Francesca

2014-01-01

The baby schema concept was originally proposed as a set of infantile traits with high appeal for humans, subsequently shown to elicit caretaking behavior and to affect cuteness perception and attentional processes. However, it is unclear whether the response to the baby schema may be extended to the human-animal bond context. Moreover, questions remain as to whether the cute response is constant and persistent or whether it changes with development. In the present study we parametrically manipulated the baby schema in images of humans, dogs, and cats. We analyzed responses of 3-6 year-old children, using both explicit (i.e., cuteness ratings) and implicit (i.e., eye gaze patterns) measures. By means of eye-tracking, we assessed children's preferential attention to images varying only for the degree of baby schema and explored participants' fixation patterns during a cuteness task. For comparative purposes, cuteness ratings were also obtained in a sample of adults. Overall our results show that the response to an infantile facial configuration emerges early during development. In children, the baby schema affects both cuteness perception and gaze allocation to infantile stimuli and to specific facial features, an effect not simply limited to human faces. In line with previous research, results confirm human positive appraisal toward animals and inform both educational and therapeutic interventions involving pets, helping to minimize risk factors (e.g., dog bites).

Soil water content evaluation considering time-invariant spatial pattern and space-variant temporal change

NASA Astrophysics Data System (ADS)

Hu, W.; Si, B. C.

2013-10-01

Soil water content (SWC) varies in space and time. The objective of this study was to evaluate soil water content distribution using a statistical model. The model divides spatial SWC series into time-invariant spatial patterns, space-invariant temporal changes, and space- and time-dependent redistribution terms. The redistribution term is responsible for the temporal changes in spatial patterns of SWC. An empirical orthogonal function was used to separate the total variations of redistribution terms into the sum of the product of spatial structures (EOFs) and temporally-varying coefficients (ECs). Model performance was evaluated using SWC data of near-surface (0-0.2 m) and root-zone (0-1.0 m) from a Canadian Prairie landscape. Three significant EOFs were identified for redistribution term for both soil layers. EOF1 dominated the variations of redistribution terms and it resulted in more changes (recharge or discharge) in SWC at wetter locations. Depth to CaCO3 layer and organic carbon were the two most important controlling factors of EOF1, and together, they explained over 80% of the variations in EOF1. Weak correlation existed between either EOF2 or EOF3 and the observed factors. A reasonable prediction of SWC distribution was obtained with this model using cross validation. The model performed better in the root zone than in the near surface, and it outperformed conventional EOF method in case soil moisture deviated from the average conditions.

Effects of hydroperiod duration on survival, developmental rate, and size at metamorphosis in boreal chorus frog tadpoles (Pseudacris maculata)

USGS Publications Warehouse

Amburgey, Staci; Funk, W. Chris; Murphy, Melanie; Muths, Erin

2012-01-01

Understanding the relationship between climate-driven habitat conditions and survival is key to preserving biodiversity in the face of rapid climate change. Hydroperiod—the length of time water is in a wetland—is a critical limiting habitat variable for amphibians as larvae must metamorphose before ponds dry. Changes in precipitation and temperature patterns are affecting hydroperiod globally, but the impact of these changes on amphibian persistence is poorly understood. We studied the responses of Boreal Chorus Frog (Pseudacris maculata) tadpoles to simulated hydroperiods (i.e., water level reductions) in the laboratory using individuals collected from ponds spanning a range of natural hydroperiods (Colorado Front Range, USA). To assess the effects of experimental hydroperiod reduction, we measured mortality, time to metamorphosis, and size at metamorphosis. We found that tadpoles grew at rates reflecting the hydroperiods of their native ponds, regardless of experimental treatment. Tadpoles from permanent ponds metamorphosed faster than those from ephemeral ponds across all experimental treatments, a pattern which may represent a predation selection gradient or countergradient variation in developmental rates. Size at metamorphosis did not vary across experimental treatments. Mortality was low overall but varied with pond of origin. Our results suggest that adaptation to local hydroperiod and/or predation and temperature conditions is important in P. maculata. Moreover, the lack of a plastic response to reduced hydroperiods suggests that P. maculata may not be able to metamorphose quickly enough to escape drying ponds. These results have important implications for amphibian persistence in ponds predicted to dry more quickly due to rapid climate change.

Isolating Age-Group Differences in Working Memory Load-Related Neural Activity: Assessing the Contribution of Working Memory Capacity Using a Partial-Trial fMRI Method

PubMed Central

Bennett, Ilana J.; Rivera, Hannah G.; Rypma, Bart

2013-01-01

Previous studies examining age-group differences in working memory load-related neural activity have yielded mixed results. When present, age-group differences in working memory capacity are frequently proposed to underlie these neural effects. However, direct relationships between working memory capacity and working memory load-related activity have only been observed in younger adults. These relationships remain untested in healthy aging. Therefore, the present study examined patterns of working memory load-related activity in 22 younger and 20 older adults and assessed the contribution of working memory capacity to these load-related effects. Participants performed a partial-trial delayed response item recognition task during functional magnetic resonance imaging. In this task, participants encoded either 2 or 6 letters, maintained them during a delay, and then indicated whether a probe was present in the memory set. Behavioral results revealed faster and more accurate responses to load 2 versus 6, with age-group differences in this load condition effect for the accuracy measure. Neuroimaging results revealed one region (medial superior frontal gyrus) that showed age-group differences in load-related activity during the retrieval period, with less (greater) neural activity for the low versus high load condition in younger (older) adults. Furthermore, for older adults, load-related activity did not vary as a function of working memory capacity. Thus, working memory-related activity varies with healthy aging, but these patterns are not due solely to working memory capacity. Neurocognitive aging theories that feature capacity will need to account for these results. PMID:23357076

Experimental designs for modeling retention patterns and separation efficiency in analysis of fatty acid methyl esters by gas chromatography-mass spectrometry.

PubMed

Skartland, Liv Kjersti; Mjøs, Svein A; Grung, Bjørn

2011-09-23

The retention behavior of components analyzed by chromatography varies with instrumental settings. Being able to predict how changes in these settings alter the elution pattern is useful, both with regards to component identification, as well as with regards to optimization of the chromatographic system. In this work, it is shown how experimental designs can be used for this purpose. Different experimental designs for response surface modeling of the separation of fatty acid methyl esters (FAME) as function of chromatographic conditions in GC have been evaluated. Full factorial, central composite, Doehlert and Box-Behnken designs were applied. A mixture of 38 FAMEs was separated on a polar cyanopropyl substituted polysilphenylene-siloxane phase capillary column. The temperature gradient, the start temperature of the gradient, and the carrier gas velocity were varied in the experiments. The modeled responses, as functions of chromatographic conditions, were retention time, retention indices, peak widths, separation efficiency and resolution between selected peak pairs. The designs that allowed inclusion of quadratic terms among the predictors performed significantly better than factorial design. Box-Behnken design provided the best results for prediction of retention, but the differences between the central composite, Doehlert and Box-Behnken designs were small. Retention indices could be modeled with much better accuracy than retention times. However, because the errors of predicted tR of closely eluting peaks were highly correlated, models of resolution (Rs) that were based on retention time had errors in the same range as corresponding models based on ECL. Copyright © 2011 Elsevier B.V. All rights reserved.

Seasonal Metabolic Acclimatization Varies in Direction and Magnitude among Populations of an Afrotropical Passerine Bird.

PubMed

Noakes, Matthew J; Wolf, Blair O; McKechnie, Andrew E

Avian metabolic responses demonstrate considerable diversity under fluctuating environmental conditions, a well-studied example being the seasonal upregulation of basal metabolic rate (BMR) and summit metabolism (M sum ) in temperate species experiencing harsh winters. Fewer studies have examined seasonal metabolic acclimatization in subtropical or tropical species. We investigated seasonal metabolic variation in an Afrotropical ploceid passerine, the white-browed sparrow-weaver (Plocepasser mahali; ∼47 g), at three sites along a climatic gradient of approximately 7°C in winter minimum air temperature (T a ). We measured M sum (n ≥ 10 per site per season) in a helox atmosphere, BMR of the same birds at thermoneutrality (T a ≈ 30°C), and resting metabolic rates at 5°C ≤ T a ≤ 20°C. Patterns of seasonal adjustments in BMR varied among populations in a manner not solely related to variation in seasonal T a extremes, ranging from BMR ∼52% higher in winter than in summer to no seasonal difference. Greater cold tolerance was found in a population at a colder desert site, manifested as higher M sum (∼25% higher) and lower helox temperature at cold limit values compared with a milder, mesic site. Our results lend support to the idea that greater variance in the pattern of seasonal metabolic responses occurs in subtropical and tropical species compared with their temperate-zone counterparts and that factors other than T a extremes (e.g., food availability) may be important in determining the magnitude and direction of seasonal metabolic adjustments in subtropical birds.

Uncertainty and operational considerations in mass prophylaxis workforce planning.

PubMed

Hupert, Nathaniel; Xiong, Wei; King, Kathleen; Castorena, Michelle; Hawkins, Caitlin; Wu, Cindie; Muckstadt, John A

2009-12-01

The public health response to an influenza pandemic or other large-scale health emergency may include mass prophylaxis using multiple points of dispensing (PODs) to deliver countermeasures rapidly to affected populations. Computer models created to date to determine "optimal" staffing levels at PODs typically assume stable patient demand for service. The authors investigated POD function under dynamic and uncertain operational environments. The authors constructed a Monte Carlo simulation model of mass prophylaxis (the Dynamic POD Simulator, or D-PODS) to assess the consequences of nonstationary patient arrival patterns on POD function under a variety of POD layouts and staffing plans. Compared are the performance of a standard POD layout under steady-state and variable patient arrival rates that may mimic real-life variation in patient demand. To achieve similar performance, PODs functioning under nonstationary patient arrival rates require higher staffing levels than would be predicted using the assumption of stationary arrival rates. Furthermore, PODs may develop severe bottlenecks unless staffing levels vary over time to meet changing patient arrival patterns. Efficient POD networks therefore require command and control systems capable of dynamically adjusting intra- and inter-POD staff levels to meet demand. In addition, under real-world operating conditions of heightened uncertainty, fewer large PODs will require a smaller total staff than many small PODs to achieve comparable performance. Modeling environments that capture the effects of fundamental uncertainties in public health disasters are essential for the realistic evaluation of response mechanisms and policies. D-PODS quantifies POD operational efficiency under more realistic conditions than have been modeled previously. The authors' experiments demonstrate that effective POD staffing plans must be responsive to variation and uncertainty in POD arrival patterns. These experiments highlight the need for command and control systems to be created to manage emergency response successfully.

The long-term prognosis of newly diagnosed epilepsy in Egypt: A retrospective cohort study from an epilepsy center in Greater Cairo.

PubMed

Ashmawi, Ayman; Hosny, Hassan; Abdelalim, Ahmed; Bianchi, Elisa; Beghi, Ettore

2016-10-01

To investigate the long-term prognosis and prognostic patterns of epilepsy in a single practice study from a developing country. Consecutive patients first seen in an epilepsy clinic in Cairo, Egypt between January 1994 and December 2009 with at least 4 years of follow-up were included. Demographic, clinical, EEG and imaging findings at diagnosis were recorded. At follow-up, treatment was adjusted as clinically indicated. The response to the first drug was defined as 6-month seizure remission. Outcome measures included 2-year remission (R) and 2-year sustained remission (SR). Prognostic patterns were early (ER) and late remission (LR), relapsing-remitting (RR) course, worsening course (WC) and no remission. Included were 287 patients aged 1-66 years and followed for 2237.0 person-years (mean 7.8 years). 244 (85%) attained 2-year R. The cumulative time dependent probability of R was 86.7% at 10 years. Only the response to the first drug predicted R. 82 (28.6%) attained 2-year SR. The probability of SR was 40.9% at 10 years. Poor treatment response and nocturnal seizures predicted lowered SR. R and SR were inversely correlated to the number of drugs. 208 patients (72.5%) entered ER, 36 (12.5%) entered LR, 138 (48.1%) had RR course. A WC was present in 24 (8.4%), 43 (15.0%) never entered remission. Prognostic patterns varied with neurological examination, MRI findings, pre-treatment seizure frequency, seizure type, number of seizure types, etiology, syndrome and response to first drug. The long-term prognosis of newly diagnosed epilepsy patients from a developing country is in keeping with published reports. Copyright © 2016 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

Individual and Day-to-Day Differences in Active Coping Predict Diurnal Cortisol Patterns among Early Adolescent Girls.

PubMed

Sladek, Michael R; Doane, Leah D; Stroud, Catherine B

2017-01-01

Prior work has identified alterations in activity of the hypothalamic-pituitary-adrenal axis as a potential mechanism underlying stress-induced emotional health problems, which disproportionately impact girls beginning in mid-adolescence. How adolescent girls differ from one another in dispositional coping tendencies and shift specific coping strategies in response to varying stressors have been theorized as important predictors of their adaptation, health, and well-being during this dynamic period of development. The goal of this study was to examine whether individual and day-to-day (within-person) differences in adolescent girls' coping responses are associated with daily patterns of hypothalamic-pituitary-adrenal axis activity, indexed by cortisol. Participants were 122 early adolescent girls (M age  = 12.39) who provided three saliva samples per day for 3 days and completed daily coping reports, as well as a standard coping survey. Participants and primary caregivers also completed objective life stress interviews. On average, girls who were more likely to respond to interpersonal stress with voluntary engagement (active) coping exhibited generally adaptive daily physiological regulation-steeper diurnal cortisol slopes, lower total diurnal cortisol output, and lower cortisol awakening responses. Chronic interpersonal stress level significantly moderated these associations in different ways for two distinct components of the diurnal pattern-the slope and cortisol awakening responses. Regarding within-person differences, using active coping more than usual was associated with higher waking cortisol the following morning, which may help to prepare adolescent girls for perceived daily demands. These findings highlight the interactive influence of stress and coping in the prediction of daily hypothalamic-pituitary-adrenal axis activity and support the stress-buffering role of active coping for adolescent girls.

Periodic buckling of constrained cylindrical elastic shells

NASA Astrophysics Data System (ADS)

Marthelot, Joel; Brun, Pierre-Thomas; Lopez Jimenez, Francisco; Reis, Pedro M.

We revisit the classic problem of buckling of a thin cylindrical elastic shell loaded either by pneumatic depressurization or axial compression. The control of the resulting dimpled pattern is achieved by using a concentric inner rigid mandrel that constrains and stabilizes the post-buckling response. Under axial compression, a regular lattice of diamond-like dimples appears sequentially on the surface of the shell to form a robust spatially extended periodic pattern. Under pressure loading, a periodic array of ridges facets the surface of the elastic cylindrical shell. The sharpness of these ridges can be readily varied and controlled through a single scalar parameter, the applied pressure. A combination of experiments, simulations and scaling analyses is used to rationalize the combined role of geometry and mechanics in the nucleation and evolution of the diamond-like dimples and ridges networks.

Effects of biotic and abiotic factors on the temporal dynamic of bat-fruit interactions

NASA Astrophysics Data System (ADS)

Laurindo, Rafael de Souza; Gregorin, Renato; Tavares, Davi Castro

2017-08-01

Mutualistic interactions between animals and plants vary over time and space based on the abundance of fruits or animals and seasonality. Little is known about this temporal dynamic and the influence of biotic and abiotic factors on the structure of interaction networks. We evaluated changes in the structure of network interactions between bats and fruits in relation to variations in rainfall. Our results suggest that fruit abundance is the main variable responsible for temporal changes in network attributes, such as network size, connectance, and number of interactions. In the same way, temperature positively affected the abundance of fruits and bats. An increase in temperature and alterations in rainfall patterns, due to human induced climate change, can cause changes in phenological patterns and fruit production, with negative consequences to biodiversity maintenance, ecological interactions, and ecosystem functioning.

Multiplex titration RT-PCR: rapid determination of gene expression patterns for a large number of genes

NASA Technical Reports Server (NTRS)

Nebenfuhr, A.; Lomax, T. L.

1998-01-01

We have developed an improved method for determination of gene expression levels with RT-PCR. The procedure is rapid and does not require extensive optimization or densitometric analysis. Since the detection of individual transcripts is PCR-based, small amounts of tissue samples are sufficient for the analysis of expression patterns in large gene families. Using this method, we were able to rapidly screen nine members of the Aux/IAA family of auxin-responsive genes and identify those genes which vary in message abundance in a tissue- and light-specific manner. While not offering the accuracy of conventional semi-quantitative or competitive RT-PCR, our method allows quick screening of large numbers of genes in a wide range of RNA samples with just a thermal cycler and standard gel analysis equipment.

Design Fragments

DTIC Science & Technology

2007-04-19

define the patterns and are better at analyzing behavior. SPQR (System for Pattern Query and Recognition) [18, 58] can recognize pattern vari- ants...Stotts. SPQR : Flexible automated design pattern extraction from source code. ase, 00:215, 2003. ISSN 1527-1366. doi: http://doi.ieeecomputersociety. org

Response of Bacterioplankton Communities to Cadmium Exposure in Coastal Water Microcosms with High Temporal Variability

PubMed Central

Wang, Kai; Xiong, Jinbo; Chen, Xinxin; Zheng, Jialai; Hu, Changju; Yang, Yina; Zhu, Jianlin

2014-01-01

Multiple anthropogenic disturbances to bacterial diversity have been investigated in coastal ecosystems, in which temporal variability in the bacterioplankton community has been considered a ubiquitous process. However, far less is known about the temporal dynamics of a bacterioplankton community responding to pollution disturbances such as toxic metals. We used coastal water microcosms perturbed with 0, 10, 100, and 1,000 μg liter−1 of cadmium (Cd) for 2 weeks to investigate temporal variability, Cd-induced patterns, and their interaction in the coastal bacterioplankton community and to reveal whether the bacterial community structure would reflect the Cd gradient in a temporally varying system. Our results showed that the bacterioplankton community structure shifted along the Cd gradient consistently after a 4-day incubation, although it exhibited some resistance to Cd at low concentration (10 μg liter−1). A process akin to an arms race between temporal variability and Cd exposure was observed, and the temporal variability overwhelmed Cd-induced patterns in the bacterial community. The temporal succession of the bacterial community was correlated with pH, dissolved oxygen, NO3−-N, NO2−-N, PO43−-P, dissolved organic carbon, and chlorophyll a, and each of these parameters contributed more to community variance than Cd did. However, elevated Cd levels did decrease the temporal turnover rate of community. Furthermore, key taxa, affiliated to the families Flavobacteriaceae, Rhodobacteraceae, Erythrobacteraceae, Piscirickettsiaceae, and Alteromonadaceae, showed a high frequency of being associated with Cd levels during 2 weeks. This study provides direct evidence that specific Cd-induced patterns in bacterioplankton communities exist in highly varying manipulated coastal systems. Future investigations on an ecosystem scale across longer temporal scales are needed to validate the observed pattern. PMID:25326310

The time course of face processing: startle eyeblink response modulation by face gender and expression.

PubMed

Duval, Elizabeth R; Lovelace, Christopher T; Aarant, Justin; Filion, Diane L

2013-12-01

The purpose of this study was to investigate the effects of both facial expression and face gender on startle eyeblink response patterns at varying lead intervals (300, 800, and 3500ms) indicative of attentional and emotional processes. We aimed to determine whether responses to affective faces map onto the Defense Cascade Model (Lang et al., 1997) to better understand the stages of processing during affective face viewing. At 300ms, there was an interaction between face expression and face gender with female happy and neutral faces and male angry faces producing inhibited startle. At 3500ms, there was a trend for facilitated startle during angry compared to neutral faces. These findings suggest that affective expressions are perceived differently in male and female faces, especially at short lead intervals. Future studies investigating face processing should take both face gender and expression into account. © 2013.

The Epidemiology of Coping in African American Adults in the Jackson Heart Study (JHS).

PubMed

Brenner, Allison B; Diez-Roux, Ana V; Gebreab, Samson Y; Schulz, Amy J; Sims, Mario

2017-12-07

Differences in coping within the African American population are not well understood, yet these differences may be critical to reducing stress, improving health, and reducing racial health disparities. Using a descriptive, exploratory analysis of the Jackson Heart Study (N = 5301), we examine correlations between coping responses and associations between coping and demographic, socioeconomic, psychosocial, and neighborhood factors. Overall, coping responses were not strongly correlated and patterns of associations between covariates and coping responses were largely inconsistent. The results suggest that coping varies substantially within this African American population and is driven mainly by psychosocial factors such as spirituality and interpersonal support. Understanding these complex relationships may inform strategies by which to intervene in the stress process to mitigate the effects of stress on health and to identify vulnerable subgroups of African Americans that might need targeted interventions to reduce exposure to stressors and improve coping capacities.

THE TASTE OF SUGARS

PubMed Central

McCaughey, Stuart A.

2008-01-01

Sugars evoke a distinctive perceptual quality (“sweetness” in humans) and are generally highly preferred. The neural basis for these phenomena is reviewed for rodents, in which detailed electrophysiological measurements have been made. A receptor has been identified that binds sweeteners and activates G-protein-mediated signaling in taste receptor cells, which leads to changes in neural firing rates in the brain, where perceptions of taste quality, intensity, and palatability are generated. Most cells in gustatory nuclei are broadly-tuned, so quality perception presumably arises from patterns of activity across neural populations. However, some manipulations affect only the most sugar-oriented cells, making it useful to consider them as a distinct neural subtype. Quality perception may also arise partly due to temporal patterns of activity to sugars, especially within sugar-oriented cells that give large but delayed responses. Non-specific gustatory neurons that are excited by both sugars and unpalatable stimuli project to ventral forebrain areas, where neural responses provide a closer match with behavioral preferences. This transition likely involves opposing excitatory and inhibitory influences by different subgroups of gustatory cells. Sweeteners are generally preferred over water, but the strength of this preference can vary across time or between individuals, and higher preferences for sugars are often associated with larger taste-evoked responses. PMID:18499254

Using Polynomials to Simplify Fixed Pattern Noise and Photometric Correction of Logarithmic CMOS Image Sensors

PubMed Central

Li, Jing; Mahmoodi, Alireza; Joseph, Dileepan

2015-01-01

An important class of complementary metal-oxide-semiconductor (CMOS) image sensors are those where pixel responses are monotonic nonlinear functions of light stimuli. This class includes various logarithmic architectures, which are easily capable of wide dynamic range imaging, at video rates, but which are vulnerable to image quality issues. To minimize fixed pattern noise (FPN) and maximize photometric accuracy, pixel responses must be calibrated and corrected due to mismatch and process variation during fabrication. Unlike literature approaches, which employ circuit-based models of varying complexity, this paper introduces a novel approach based on low-degree polynomials. Although each pixel may have a highly nonlinear response, an approximately-linear FPN calibration is possible by exploiting the monotonic nature of imaging. Moreover, FPN correction requires only arithmetic, and an optimal fixed-point implementation is readily derived, subject to a user-specified number of bits per pixel. Using a monotonic spline, involving cubic polynomials, photometric calibration is also possible without a circuit-based model, and fixed-point photometric correction requires only a look-up table. The approach is experimentally validated with a logarithmic CMOS image sensor and is compared to a leading approach from the literature. The novel approach proves effective and efficient. PMID:26501287

Biomarker responses to environmental contamination in estuaries: A comparative multi-taxa approach.

PubMed

Duarte, Irina A; Reis-Santos, Patrick; França, Susana; Cabral, Henrique; Fonseca, Vanessa F

2017-08-01

Estuaries are highly productive ecosystems subjected to numerous anthropogenic pressures with consequent environmental quality degradation. In this study, multiple biomarker responses [superoxide dismutase (SOD), catalase (CAT), ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST) activities, as well as lipid peroxidation (LPO) and DNA damage (DNAd)] were determined in two fish (Dicentrarchus labrax and Pomatoschistus microps) and four macroinvertebrate species (Carcinus maenas, Crangon crangon, Hediste diversicolor and Scrobicularia plana) from the Ria de Aveiro and Tejo estuaries over distinct months. Two sites per estuarine system were selected based on anthropogenic pressures and magnitude of environmental contamination. Antioxidant enzyme activities in fish species suggested a ubiquitous response to oxidative stress, while biotransformation and effect biomarkers exhibited higher spatial and temporal variation. In invertebrate species, biotransformation enzyme activity was clearly less variable than in fish evidencing lower xenobiotic transformation capability. Overall, largest biomarker responses were found in the most contaminated sites (Tejo), yet species-specific patterns were evident. These should be factored in multi-taxa approaches, considering that the differential functional traits of species, such as habitat use, life-stage, feeding or physiology can influence exposure routes and biomarker responses. The Integrated Biomarker Response index highlighted patterns in biomarker responses which were not immediately evident when analyzing biomarkers individually. Overall, results provided insights into the complexity of species responses to contamination in naturally varying estuarine environments. Ultimately, multi-taxa and multi-biomarker approaches provide a comprehensive and complementary view of ecosystem health, encompassing diverse forms of biological integration and exposure routes, and allow the validation of results among markers and species. Copyright © 2017 Elsevier B.V. All rights reserved.

Multilevel regression models describing regional patterns of invertebrate and algal responses to urbanization across the USA

USGS Publications Warehouse

Cuffney, T.F.; Kashuba, R.; Qian, S.S.; Alameddine, I.; Cha, Y.K.; Lee, B.; Coles, J.F.; McMahon, G.

2011-01-01

Multilevel hierarchical regression was used to examine regional patterns in the responses of benthic macroinvertebrates and algae to urbanization across 9 metropolitan areas of the conterminous USA. Linear regressions established that responses (intercepts and slopes) to urbanization of invertebrates and algae varied among metropolitan areas. Multilevel hierarchical regression models were able to explain these differences on the basis of region-scale predictors. Regional differences in the type of land cover (agriculture or forest) being converted to urban and climatic factors (precipitation and air temperature) accounted for the differences in the response of macroinvertebrates to urbanization based on ordination scores, total richness, Ephemeroptera, Plecoptera, Trichoptera richness, and average tolerance. Regional differences in climate and antecedent agriculture also accounted for differences in the responses of salt-tolerant diatoms, but differences in the responses of other diatom metrics (% eutraphenic, % sensitive, and % silt tolerant) were best explained by regional differences in soils (mean % clay soils). The effects of urbanization were most readily detected in regions where forest lands were being converted to urban land because agricultural development significantly degraded assemblages before urbanization and made detection of urban effects difficult. The effects of climatic factors (temperature, precipitation) on background conditions (biogeographic differences) and rates of response to urbanization were most apparent after accounting for the effects of agricultural development. The effects of climate and land cover on responses to urbanization provide strong evidence that monitoring, mitigation, and restoration efforts must be tailored for specific regions and that attainment goals (background conditions) may not be possible in regions with high levels of prior disturbance (e.g., agricultural development). ?? 2011 by The North American Benthological Society.

Attachment linked predictors of women's emotional and cognitive responses to infant distress.

PubMed

Leerkes, Esther M; Siepak, Kathryn J

2006-03-01

The purpose of this study was to examine associations among women's emotional and cognitive responses to infant fear and anger and to identify attachment linked predictors of these responses. Four hundred and forty Caucasian and African American undergraduate college women viewed video clips of two crying infants, one displaying anger and the other displaying fear. They identified what the infants were feeling, made causal attributions about the cause of crying, rated their own emotional reactions to the crying infants, and reported on the extent to which their parents met their emotional needs in childhood and their current adult attachment patterns. Emotional and cognitive responses to infant fear and anger were interrelated. Consistent with prediction, a history of parental emotional rejection and adult attachment anxiety and avoidance correlated negatively with accurate identification of emotions and positively with negative attributions, amusement, and neutral responses to infant distress. Adult attachment security moderated the effects of early parental rejection on emotional and cognitive responses to infant distress, and these results varied based on race and parent gender. Results are discussed from an attachment theory perspective.

Pattern Water Use Efficiency perspective on degradation and recovery of shrublands across Mediterranean to Arid transition zones

NASA Astrophysics Data System (ADS)

Shoshany, Maxim

2017-04-01

Shrublands cover a total of 12.7 million km2 , a considerable part of them along semi-arid to arid transition zones. Varying patterns of shrubs, grasses and barren land along such climatic gradients express the spatial dimension of climate change and human disturbance which attracted limited attention in the eco-geomorphic literature. Questions concerning relationships between rainfall, shrublands biomass and their patterns are fundamental for the understanding of these ecosystems response to the expected changes in water availability due to global warming and the increase in human disturbance to natural ecosystems following World population growth. While processes leading to the formation of patterns had attracted considerable attention, the spatial dimension of Water Use Efficiency (WUE) which is a parameter measuring ecosystems productivity in relation to water availability is severely missing. Relative shrub cover is a primary estimator of the fraction of water utilized for shrubs growth. Edge effects must be considered as well in fragmented ecosystems in general and in hot regions in particular since soil temperature in hot regions which frequently exceed 50oC during summer months decreases photosynthesis and productivity in plants bordering bare soil. This edge effect is decreasing with the increase in shrubs' height. Pattern Water Use Efficiency describes the combined effect of shrub cover, shrub height and shrub patches edge zone proportion on water use efficiency. In my presentation I will first present mapping od PWUEs across Mediterranean to arid transition zones in the Eastern Mediterranean. Then I will present several mathematical models describing PWUE for simulated patterns, searching for the spatial parameterization providing the highest sensitivity to patterns responses to changes in habitat conditions. Such simulations would allow us to discuss several PWUE strategies for shrublands recovery under the current scenarios of climate change and human driven degradation.

Changes in intrapopulation resource use patterns of an endangered raptor in response to a disease-mediated crash in prey abundance.

PubMed

Moleón, Marcos; Sebastián-González, Esther; Sánchez-Zapata, José A; Real, Joan; Pires, Mathias M; Gil-Sánchez, José M; Bautista, Jesús; Palma, Luís; Bayle, Patrick; Guimarães, Paulo R; Beja, Pedro

2012-11-01

1. A long-standing question in ecology is how natural populations respond to a changing environment. Emergent optimal foraging theory-based models for individual variation go beyond the population level and predict how its individuals would respond to disturbances that produce changes in resource availability. 2. Evaluating variations in resource use patterns at the intrapopulation level in wild populations under changing environmental conditions would allow to further advance in the research on foraging ecology and evolution by gaining a better idea of the underlying mechanisms explaining trophic diversity. 3. In this study, we use a large spatio-temporal scale data set (western continental Europe, 1968-2006) on the diet of Bonelli's Eagle Aquila fasciata breeding pairs to analyse the predator trophic responses at the intrapopulation level to a prey population crash. In particular, we borrow metrics from studies on network structure and intrapopulation variation to understand how an emerging infectious disease [the rabbit haemorrhagic disease (RHD)] that caused the density of the eagle's primary prey (rabbit Oryctolagus cuniculus) to dramatically drop across Europe impacted on resource use patterns of this endangered raptor. 4. Following the major RHD outbreak, substantial changes in Bonelli's Eagle's diet diversity and organisation patterns at the intrapopulation level took place. Dietary variation among breeding pairs was larger after than before the outbreak. Before RHD, there were no clusters of pairs with similar diets, but significant clustering emerged after RHD. Moreover, diets at the pair level presented a nested pattern before RHD, but not after. 5. Here, we reveal how intrapopulation patterns of resource use can quantitatively and qualitatively vary, given drastic changes in resource availability. 6. For the first time, we show that a pathogen of a prey species can indirectly impact the intrapopulation patterns of resource use of an endangered predator. © 2012 The Authors. Journal of Animal Ecology © 2012 British Ecological Society.

Compression and release dynamics of an active matter system of Euglena gracilis

NASA Astrophysics Data System (ADS)

Lam, Amy; Tsang, Alan C. H.; Ouellette, Nicholas; Riedel-Kruse, Ingmar

Active matter, defined as ensembles of self-propelled particles, encompasses a large variety of systems at all scales, from nanoparticles to bird flocks. Though various models and simulations have been created to describe the dynamics of these systems, experimental verification has been difficult to obtain. This is frequently due to the complex interaction rules which govern the particle behavior, in turn making systematic varying of parameters impossible. Here, we propose a model for predicting the system evolution of compression and release of an active system based on experiments and simulations. In particular, we consider ensembles of the unicellular, photo-responsive algae, Euglena gracilis, under light stimulation. By varying the spatiotemporal light patterns, we are able to finely adjust cell densities and achieve arbitrary non-homogeneous distributions, including compression into high-density aggregates of varying geometries. We observe the formation of depletion zones after the release of the confining stimulus and investigate the effects of the density distribution and particle rotational noise on the depletion. These results provide implications for defining state parameters which determine system evolution.

The Role of the Pulmonary Embolism Response Team: How to Build One, Who to Include, Scenarios, Organization, and Algorithms.

PubMed

Galmer, Andrew; Weinberg, Ido; Giri, Jay; Jaff, Michael; Weinberg, Mitchell

2017-09-01

Pulmonary embolism response teams (PERTs) are multidisciplinary response teams aimed at delivering a range of diagnostic and therapeutic modalities to patients with pulmonary embolism. These teams have gained traction on a national scale. However, despite sharing a common goal, individual PERT programs are quite individualized-varying in their methods of operation, team structures, and practice patterns. The tendency of such response teams is to become intensely structured, algorithmic, and inflexible. However, in their current form, PERT programs are quite the opposite. They are being creatively customized to meet the needs of the individual institution based on available resources, skills, personnel, and institutional goals. After a review of the essential core elements needed to create and operate a PERT team in any form, this article will discuss the more flexible feature development of the nascent PERT team. These include team planning, member composition, operational structure, benchmarking, market analysis, and rudimentary financial operations. Copyright © 2017 Elsevier Inc. All rights reserved.

Combustion Instability Analysis and the Effects of Drop Size on Acoustic Driving Rocket Flow

NASA Technical Reports Server (NTRS)

Harper, Brent (Technical Monitor); Ellison, L. Renea; Moser, Marlow D.

2004-01-01

High frequency combustion instability, the most destructive kind, is generally solved on a per engine basis. The instability often is the result of compounding acoustic oscillations, usually from the propellant combustion itself. To counteract the instability the chamber geometry can be changed and/or the method of propellant injection can be altered. This experiment will alter the chamber dimensions slightly; using a cylindrical shape of constant diameter and the length will be varied from six to twelve inches in three-inch increments. The main flowfield will be the products of a high OF hydrogen/oxygen flow. The liquid fuel will be injected into this flowfield using a modulated injector. It will allow for varied droplet size, feed rate, spray pattern, and location for the mixture within the chamber. The response will be deduced from the chamber pressure oscillations.

Probability of atrial fibrillation after ablation: Using a parametric nonlinear temporal decomposition mixed effects model.

PubMed

Rajeswaran, Jeevanantham; Blackstone, Eugene H; Ehrlinger, John; Li, Liang; Ishwaran, Hemant; Parides, Michael K

2018-01-01

Atrial fibrillation is an arrhythmic disorder where the electrical signals of the heart become irregular. The probability of atrial fibrillation (binary response) is often time varying in a structured fashion, as is the influence of associated risk factors. A generalized nonlinear mixed effects model is presented to estimate the time-related probability of atrial fibrillation using a temporal decomposition approach to reveal the pattern of the probability of atrial fibrillation and their determinants. This methodology generalizes to patient-specific analysis of longitudinal binary data with possibly time-varying effects of covariates and with different patient-specific random effects influencing different temporal phases. The motivation and application of this model is illustrated using longitudinally measured atrial fibrillation data obtained through weekly trans-telephonic monitoring from an NIH sponsored clinical trial being conducted by the Cardiothoracic Surgery Clinical Trials Network.

Physiological basis of climate change impacts on North American inland fishes

USGS Publications Warehouse

Whitney, James E.; Al-Chokhachy, Robert K.; Bunnell, David B.; Caldwell, Colleen A.; Cooke, Steven J.; Eliason, Erika J.; Rogers, Mark W.; Lynch, Abigail J.; Paukert, Craig P.

2016-01-01

Global climate change is altering freshwater ecosystems and affecting fish populations and communities. Underpinning changes in fish distribution and assemblage-level responses to climate change are individual-level physiological constraints. In this review, we synthesize the mechanistic effects of climate change on neuroendocrine, cardiorespiratory, immune, osmoregulatory, and reproductive systems of freshwater and diadromous fishes. Observed climate change effects on physiological systems are varied and numerous, including exceedance of critical thermal tolerances, decreased cardiorespiratory performance, compromised immune function, and altered patterns of individual reproductive investment. However, effects vary widely among and within species because of species, population, and even sex-specific differences in sensitivity and resilience and because of habitat-specific variation in the magnitude of climate-related environmental change. Research on the interactive effects of climate change with other environmental stressors across a broader range of fish diversity is needed to further our understanding of climate change effects on fish physiology.

Tunable ferrite-based metamaterial structure and its application to a leaky-wave antenna

NASA Astrophysics Data System (ADS)

Berneti, Elahe Kargar; Ghalibafan, Javad

2018-06-01

In this paper, a new magnetically tunable substrate integrated waveguide (SIW) with composite right/left-handed (CRLH) response is presented. The structure consists of an array of interdigital slots on the upper wall of a SIW line with normally magnetized ferrite substrate. The electromagnetic properties of this structure are studied and the dispersion diagram is considered. The simulated results show that the proposed structure has a separate right- and left-handed leakage frequency region which can be simply controlled by varying the applied ferrite magnetic bias field. As an application, this leakage frequency band is exploited to build a new leaky-wave antenna (LWA) which its radiation pattern can be independently scanned by varying the frequency or the magnetic bias field. As another advantage, there is not any mechanical switch or electrical tuning chip in the proposed leaky-wave antenna.

Influence of geometry on the electrochemical response of carbon interdigitated microelectrodes

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

Kostecki, R.; Song, X.Y.; Kinoshita, K.

2000-05-01

Microelectrodes were fabricated by carbonizing photoresist (700--1,000 C) that was patterned on a Si wafer by use of a mask and UV photolithography. Two geometric designs of interdigitated carbon microelectrodes were produced with dimensions of about 500 {micro}m length and 50 {micro}m width. The carbon structures were characterized by Raman spectroscopy, atomic force microscopy, and optical microscopy. The electrochemical response of the microelectrodes was investigated by cyclic voltammetry using the I{sub 3}{sup {minus}}/I{sup {minus}} redox couple. The collection efficiencies of carbon inderdigitated array electrodes (IDAEs) varied from 59 to 90% depending on the cell size, geometry, and generator-collector arrangement. Thesemore » collection efficiencies are comparable to those reported with multiband (n > 25 bands) IDAEs.« less

Flexibility of centromere and kinetochore structures

PubMed Central

Burrack, Laura S.; Berman, Judith

2012-01-01

Centromeres, and the kinetochores that assemble on them, are essential for accurate chromosome segregation. Diverse centromere organization patterns and kinetochore structures have evolved in eukaryotes ranging from yeast to humans. In addition, centromere DNA and kinetochore position can vary even within individual cells. This flexibility manifests in several ways: centromere DNA sequences evolve rapidly, kinetochore positions shift in response to altered chromosome structure, and kinetochore complex numbers change in response to fluctuations in kinetochore protein levels. Despite their differences, all of these diverse structures promote efficient chromosome segregation. This robustness is inherent to chromosome segregation mechanisms and balances genome stability with adaptability. In this review, we explore the mechanisms and consequences of centromere and kinetochore flexibility as well as the benefits and limitations of different experimental model systems for studying them. PMID:22445183

Behavioral and brain pattern differences between acting and observing in an auditory task

PubMed Central

Karanasiou, Irene S; Papageorgiou, Charalabos; Tsianaka, Eleni I; Matsopoulos, George K; Ventouras, Errikos M; Uzunoglu, Nikolaos K

2009-01-01

Background Recent research has shown that errors seem to influence the patterns of brain activity. Additionally current notions support the idea that similar brain mechanisms are activated during acting and observing. The aim of the present study was to examine the patterns of brain activity of actors and observers elicited upon receiving feedback information of the actor's response. Methods The task used in the present research was an auditory identification task that included both acting and observing settings, ensuring concurrent ERP measurements of both participants. The performance of the participants was investigated in conditions of varying complexity. ERP data were analyzed with regards to the conditions of acting and observing in conjunction to correct and erroneous responses. Results The obtained results showed that the complexity induced by cue dissimilarity between trials was a demodulating factor leading to poorer performance. The electrophysiological results suggest that feedback information results in different intensities of the ERP patterns of observers and actors depending on whether the actor had made an error or not. The LORETA source localization method yielded significantly larger electrical activity in the supplementary motor area (Brodmann area 6), the posterior cingulate gyrus (Brodmann area 31/23) and the parietal lobe (Precuneus/Brodmann area 7/5). Conclusion These findings suggest that feedback information has a different effect on the intensities of the ERP patterns of actors and observers depending on whether the actor committed an error. Certain neural systems, including medial frontal area, posterior cingulate gyrus and precuneus may mediate these modulating effects. Further research is needed to elucidate in more detail the neuroanatomical and neuropsychological substrates of these systems. PMID:19154586

Linking Plagioclase Zoning Patterns to Active Magma Processes

NASA Astrophysics Data System (ADS)

Izbekov, P. E.; Nicolaysen, K. P.; Neill, O. K.; Shcherbakov, V.; Eichelberger, J. C.; Plechov, P.

2016-12-01

Plagioclase, one of the most common and abundant mineral phases in volcanic products, will vary in composition in response to changes in temperature, pressure, composition of the ambient silicate melt, and melt H2O concentration. Changes in these parameters may cause dissolution or growth of plagioclase crystals, forming characteristic textural and compositional variations (zoning patterns), the complete core-to-rim sequence of which describes events experienced by an individual crystal from its nucleation to the last moments of its growth. Plagioclase crystals in a typical volcanic rock may look drastically dissimilar despite their spatial proximity and the fact that they have erupted together. Although they shared last moments of their growth during magma ascent and eruption, their prior experiences could be very different, as plagioclase crystals often come from different domains of the same magma system. Distinguishing similar zoning patterns, correlating them across the entire population of plagioclase crystals, and linking these patterns to specific perturbations in the magmatic system may provide additional perspective on the variety, extent, and timing of magma processes at active volcanic systems. Examples of magma processes, which may be distinguished based on plagioclase zoning patterns, include (1) cooling due to heat loss, (2) heating and/or pressure build up due to an input of new magmatic material, (3) pressure drop in response to magma system depressurization, and (4) crystal transfer between different magma domains/bodies. This review will include contrasting examples of zoning patters from recent eruptions of Augustine and Cleveland Volcanoes in Alaska, Sakurajima Volcano in Japan, Karymsky, Bezymianny, and Tolbachik Volcanoes in Kamchatka, as well as from the drilling into an active magma body at Krafla, Iceland.

Seasonal climate change patterns due to cumulative CO2 emissions

NASA Astrophysics Data System (ADS)

Partanen, Antti-Ilari; Leduc, Martin; Damon Matthews, H.

2017-07-01

Cumulative CO2 emissions are near linearly related to both global and regional changes in annual-mean surface temperature. These relationships are known as the transient climate response to cumulative CO2 emissions (TCRE) and the regional TCRE (RTCRE), and have been shown to remain approximately constant over a wide range of cumulative emissions. Here, we assessed how well this relationship holds for seasonal patterns of temperature change, as well as for annual-mean and seasonal precipitation patterns. We analyzed an idealized scenario with CO2 concentration growing at an annual rate of 1% using data from 12 Earth system models from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Seasonal RTCRE values for temperature varied considerably, with the highest seasonal variation evident in the Arctic, where RTCRE was about 5.5 °C per Tt C for boreal winter and about 2.0 °C per Tt C for boreal summer. Also the precipitation response in the Arctic during boreal winter was stronger than during other seasons. We found that emission-normalized seasonal patterns of temperature change were relatively robust with respect to time, though they were sub-linear with respect to emissions particularly near the Arctic. Moreover, RTCRE patterns for precipitation could not be quantified robustly due to the large internal variability of precipitation. Our results suggest that cumulative CO2 emissions are a useful metric to predict regional and seasonal changes in precipitation and temperature. This extension of the TCRE framework to seasonal and regional climate change is helpful for communicating the link between emissions and climate change to policy-makers and the general public, and is well-suited for impact studies that could make use of estimated regional-scale climate changes that are consistent with the carbon budgets associated with global temperature targets.

Contrasting species and functional beta diversity in montane ant assemblages.

PubMed

Bishop, Tom R; Robertson, Mark P; van Rensburg, Berndt J; Parr, Catherine L

2015-09-01

Beta diversity describes the variation in species composition between sites and can be used to infer why different species occupy different parts of the globe. It can be viewed in a number of ways. First, it can be partitioned into two distinct patterns: turnover and nestedness. Second, it can be investigated from either a species identity or a functional-trait point of view. We aim to document for the first time how these two aspects of beta diversity vary in response to a large environmental gradient. Maloti-Drakensberg Mountains, southern Africa. We sampled ant assemblages along an extensive elevational gradient (900-3000 m a.s.l.) twice yearly for 7 years, and collected functional-trait information related to the species' dietary and habitat-structure preferences. We used recently developed methods to partition species and functional beta diversity into their turnover and nestedness components. A series of null models were used to test whether the observed beta diversity patterns differed from random expectations. Species beta diversity was driven by turnover, but functional beta diversity was composed of both turnover and nestedness patterns at different parts of the gradient. Null models revealed that deterministic processes were likely to be responsible for the species patterns but that the functional changes were indistinguishable from stochasticity. Different ant species are found with increasing elevation, but they tend to represent an increasingly nested subset of the available functional strategies. This finding is unique and narrows down the list of possible factors that control ant existence across elevation. We conclude that diet and habitat preferences have little role in structuring ant assemblages in montane environments and that some other factor must be driving the non-random patterns of species turnover. This finding also highlights the importance of distinguishing between different kinds of beta diversity.

Meal frequencies in early adolescence predict meal frequencies in late adolescence and early adulthood.

PubMed

Pedersen, Trine Pagh; Holstein, Bjørn E; Flachs, Esben Meulengracht; Rasmussen, Mette

2013-05-04

Health and risk behaviours tend to be maintained from adolescence into adulthood. There is little knowledge on whether meal frequencies in adolescence are maintained into adulthood. We investigated whether breakfast, lunch and evening meal frequencies in early adolescence predicted meal frequencies in late adolescence and in early adulthood. Further, the modifying effect of gender and adolescent family structure were investigated. National representative sample of 15-year-olds in Denmark with 4 and 12 year follow-up studies with measurement of breakfast, lunch and evening meal frequencies. A total of 561 persons completed questionnaires at age 15 years (baseline 1990, n=847, response rate 84.6%), age 19 years (n=729, response rate 73.2%) and age 27 years (n=614, response rate 61.6%). Low meal frequencies at age 15 years was a significant predictor for having low meal frequencies at age 19 years (odds ratio (OR, 95% CI)) varying between 2.11, 1.33-3.34 and 7.48, 3.64-15.41). Also, low meal frequencies at age 19 years predicted low meal frequencies at age 27 years (OR varying between 2.26, 1.30-3.91 and 4.38, 2.36-8.13). Significant predictions over the full study period were seen for low breakfast frequency and low lunch frequency (OR varying between 1.78, 1.13-2.81 and 2.58, 1.31-5.07). Analyses stratified by gender showed the same patterns (OR varying between 1.88, 1.13-3.14 and 8.30, 2.85-24.16). However, the observed predictions were not statistical significant among men between age 15 and 27 years. Analyses stratified by adolescent family structure revealed different lunch predictions in strata. Having low meal frequencies in early adolescence predicted low meal frequencies in late adolescence and early adulthood. We propose that promotion of regular meals become a prioritised issue within health education.

Long term leaf phenology and leaf exchange strategies of a cerrado savanna community

NASA Astrophysics Data System (ADS)

de Camargo, Maria Gabriela G.; Costa Alberton, Bruna; de Carvalho, Gustavo H.; Magalhães, Paula A. N. R.; Morellato, Leonor Patrícia C.

2017-04-01

Leaf development and senescence cycles are linked to a range of ecosystem processes, affecting seasonal patterns of atmosphere-ecosystem carbon and energy exchanges, resource availability and nutrient cycling. The degree of deciduousness of tropical trees and communities depend on ecosystems characteristics such as amount of biomass, species diversity and the strength and length of the dry season. Besides defining the growing season, deciduousness can also be an indicator of species response to climate changes in the tropics, mainly because severity of dry season can intensify leaf loss. Based on seven-years of phenological observations (2005 to 2011) we describe the long-term patterns of leafing phenology of a Brazilian cerrado savanna, aiming to (i) identify leaf exchange strategies of species, quantifying the degree of deciduousness, and verify whether these strategies vary among years depending on the length and strength of the dry seasons; (ii) define the growing seasons along the years and the main drivers of leaf flushing in the cerrado. We analyzed leafing patterns of 107 species and classified 69 species as deciduous (11 species), semi-deciduous (29) and evergreen (29). Leaf exchange was markedly seasonal, as expected for seasonal tropical savannas. Leaf fall predominated in the dry season, peaking in July, and leaf flushing in the transition between dry to wet seasons, peaking in September. Leafing patterns were similar among years with the growing season starting at the end of dry season, in September, for most species. However, leaf exchange strategies varied among years for most species (65%), except for evergreen strategy, mainly constant over years. Leafing patterns of cerrado species were strongly constrained by rainfall. The length of the dry season and rainfall intensity were likely affecting the individuals' leaf exchange strategies and suggesting a differential resilience of species to changes of rainfall regime, predicted on future global change scenarios.

Uniform modeling of bacterial colony patterns with varying nutrient and substrate

NASA Astrophysics Data System (ADS)

Schwarcz, Deborah; Levine, Herbert; Ben-Jacob, Eshel; Ariel, Gil

2016-04-01

Bacteria develop complex patterns depending on growth condition. For example, Bacillus subtilis exhibit five different patterns depending on substrate hardness and nutrient concentration. We present a unified integro-differential model that reproduces the entire experimentally observed morphology diagram at varying nutrient concentrations and substrate hardness. The model allows a comprehensive and quantitative comparison between experimental and numerical variables and parameters, such as colony growth rate, nutrient concentration and diffusion constants. As a result, the role of the different physical mechanisms underlying and regulating the growth of the colony can be evaluated.

The Feasibility of Using a Galvanic Cell Array for Corrosion Detection and Solution Monitoring

NASA Technical Reports Server (NTRS)

Kolody, Mark; Calle, Luz-Marina; Zeitlin, Nancy P. (Technical Monitor)

2003-01-01

An initial investigation into the response of the individual galvanic couples was conducted using potentiodynamic polarization measurements of solutions under conditions of varying corrosivity. It is hypothesized that the differing electrodes may provide a means to further investigate the corrosive nature of the analyte through genetic algorithms and pattern recognition techniques. The robust design of the electrochemical sensor makes its utilization in space exploration particularly attractive. Since the electrodes are fired on a ceramic substrate at 900 C, they may be one of the most rugged sensors available for the anticipated usage.

Scaling properties in time-varying networks with memory

NASA Astrophysics Data System (ADS)

Kim, Hyewon; Ha, Meesoon; Jeong, Hawoong

2015-12-01

The formation of network structure is mainly influenced by an individual node's activity and its memory, where activity can usually be interpreted as the individual inherent property and memory can be represented by the interaction strength between nodes. In our study, we define the activity through the appearance pattern in the time-aggregated network representation, and quantify the memory through the contact pattern of empirical temporal networks. To address the role of activity and memory in epidemics on time-varying networks, we propose temporal-pattern coarsening of activity-driven growing networks with memory. In particular, we focus on the relation between time-scale coarsening and spreading dynamics in the context of dynamic scaling and finite-size scaling. Finally, we discuss the universality issue of spreading dynamics on time-varying networks for various memory-causality tests.

Decision making and preferences for acoustic signals in choice situations by female crickets.

PubMed

Gabel, Eileen; Kuntze, Janine; Hennig, R Matthias

2015-08-01

Multiple attributes usually have to be assessed when choosing a mate. Efficient choice of the best mate is complicated if the available cues are not positively correlated, as is often the case during acoustic communication. Because of varying distances of signalers, a female may be confronted with signals of diverse quality at different intensities. Here, we examined how available cues are weighted for a decision by female crickets. Two songs with different temporal patterns and/or sound intensities were presented in a choice paradigm and compared with female responses from a no-choice test. When both patterns were presented at equal intensity, preference functions became wider in choice situations compared with a no-choice paradigm. When the stimuli in two-choice tests were presented at different intensities, this effect was counteracted as preference functions became narrower compared with choice tests using stimuli of equal intensity. The weighting of intensity differences depended on pattern quality and was therefore non-linear. A simple computational model based on pattern and intensity cues reliably predicted female decisions. A comparison of processing schemes suggested that the computations for pattern recognition and directionality are performed in a network with parallel topology. However, the computational flow of information corresponded to serial processing. © 2015. Published by The Company of Biologists Ltd.

Mapping Informative Clusters in a Hierarchial Framework of fMRI Multivariate Analysis

PubMed Central

Xu, Rui; Zhen, Zonglei; Liu, Jia

2010-01-01

Pattern recognition methods have become increasingly popular in fMRI data analysis, which are powerful in discriminating between multi-voxel patterns of brain activities associated with different mental states. However, when they are used in functional brain mapping, the location of discriminative voxels varies significantly, raising difficulties in interpreting the locus of the effect. Here we proposed a hierarchical framework of multivariate approach that maps informative clusters rather than voxels to achieve reliable functional brain mapping without compromising the discriminative power. In particular, we first searched for local homogeneous clusters that consisted of voxels with similar response profiles. Then, a multi-voxel classifier was built for each cluster to extract discriminative information from the multi-voxel patterns. Finally, through multivariate ranking, outputs from the classifiers were served as a multi-cluster pattern to identify informative clusters by examining interactions among clusters. Results from both simulated and real fMRI data demonstrated that this hierarchical approach showed better performance in the robustness of functional brain mapping than traditional voxel-based multivariate methods. In addition, the mapped clusters were highly overlapped for two perceptually equivalent object categories, further confirming the validity of our approach. In short, the hierarchical framework of multivariate approach is suitable for both pattern classification and brain mapping in fMRI studies. PMID:21152081

Modelling survival: exposure pattern, species sensitivity and uncertainty

PubMed Central

Ashauer, Roman; Albert, Carlo; Augustine, Starrlight; Cedergreen, Nina; Charles, Sandrine; Ducrot, Virginie; Focks, Andreas; Gabsi, Faten; Gergs, André; Goussen, Benoit; Jager, Tjalling; Kramer, Nynke I.; Nyman, Anna-Maija; Poulsen, Veronique; Reichenberger, Stefan; Schäfer, Ralf B.; Van den Brink, Paul J.; Veltman, Karin; Vogel, Sören; Zimmer, Elke I.; Preuss, Thomas G.

2016-01-01

The General Unified Threshold model for Survival (GUTS) integrates previously published toxicokinetic-toxicodynamic models and estimates survival with explicitly defined assumptions. Importantly, GUTS accounts for time-variable exposure to the stressor. We performed three studies to test the ability of GUTS to predict survival of aquatic organisms across different pesticide exposure patterns, time scales and species. Firstly, using synthetic data, we identified experimental data requirements which allow for the estimation of all parameters of the GUTS proper model. Secondly, we assessed how well GUTS, calibrated with short-term survival data of Gammarus pulex exposed to four pesticides, can forecast effects of longer-term pulsed exposures. Thirdly, we tested the ability of GUTS to estimate 14-day median effect concentrations of malathion for a range of species and use these estimates to build species sensitivity distributions for different exposure patterns. We find that GUTS adequately predicts survival across exposure patterns that vary over time. When toxicity is assessed for time-variable concentrations species may differ in their responses depending on the exposure profile. This can result in different species sensitivity rankings and safe levels. The interplay of exposure pattern and species sensitivity deserves systematic investigation in order to better understand how organisms respond to stress, including humans. PMID:27381500

Genome-wide characterization of the WRKY gene family in radish (Raphanus sativus L.) reveals its critical functions under different abiotic stresses.

PubMed

Karanja, Bernard Kinuthia; Fan, Lianxue; Xu, Liang; Wang, Yan; Zhu, Xianwen; Tang, Mingjia; Wang, Ronghua; Zhang, Fei; Muleke, Everlyne M'mbone; Liu, Liwang

2017-11-01

The radish WRKY gene family was genome-widely identified and played critical roles in response to multiple abiotic stresses. The WRKY is among the largest transcription factors (TFs) associated with multiple biological activities for plant survival, including control response mechanisms against abiotic stresses such as heat, salinity, and heavy metals. Radish is an important root vegetable crop and therefore characterization and expression pattern investigation of WRKY transcription factors in radish is imperative. In the present study, 126 putative WRKY genes were retrieved from radish genome database. Protein sequence and annotation scrutiny confirmed that RsWRKY proteins possessed highly conserved domains and zinc finger motif. Based on phylogenetic analysis results, RsWRKYs candidate genes were divided into three groups (Group I, II and III) with the number 31, 74, and 20, respectively. Additionally, gene structure analysis revealed that intron-exon patterns of the WRKY genes are highly conserved in radish. Linkage map analysis indicated that RsWRKY genes were distributed with varying densities over nine linkage groups. Further, RT-qPCR analysis illustrated the significant variation of 36 RsWRKY genes under one or more abiotic stress treatments, implicating that they might be stress-responsive genes. In total, 126 WRKY TFs were identified from the R. sativus genome wherein, 35 of them showed abiotic stress-induced expression patterns. These results provide a genome-wide characterization of RsWRKY TFs and baseline for further functional dissection and molecular evolution investigation, specifically for improving abiotic stress resistances with an ultimate goal of increasing yield and quality of radish.

Results of a survey regarding irradiation of internal mammary chain in patients with breast cancer: practice is culture driven rather than evidence based.

PubMed

Taghian, Alphonse; Jagsi, Reshma; Makris, Andreas; Goldberg, Saveli; Ceilley, Elizabeth; Grignon, Laurent; Powell, Simon

2004-11-01

To examine the self-reported practice patterns of radiation oncologists in North America and Europe regarding radiotherapy to the internal mammary lymph node chain (IMC) in breast cancer patients. A survey questionnaire was sent in 2001 to physician members of the American Society for Therapeutic Radiology and Oncology and European Society for Therapeutic Radiology and Oncology regarding their management of breast cancer. Respondents were asked whether they would treat the IMC in several clinical scenarios. A total of 435 responses were obtained from European and 702 responses from North American radiation oncologists. Respondents were increasingly likely to report IMC irradiation in scenarios with greater axillary involvement. Responses varied widely among different European regions, the United States, and Canada (p < 0.01). European respondents were more likely to treat the IMC (p < 0.01) than their North American counterparts. Academic physicians were more likely to treat the IMC than those in nonacademic positions (p < 0.01). The results of this study revealed significant international variation in attitudes regarding treatment of the IMC. The international patterns of variation mirror the divergent conclusions of studies conducted in the different regions, indicating that physicians may rely preferentially on evidence from local studies when making difficult treatment decisions. These variations in self-reported practice patterns indicate the need for greater data in this area, particularly from international cooperative trials. The cultural predispositions documented in this study are important to recognize, because they may continue to affect physician attitudes and practices, even as greater evidence accumulates.

Task-level feedback can explain temporal recruitment of spatially fixed muscle synergies throughout postural perturbations

PubMed Central

Safavynia, Seyed A.

2012-01-01

Recent evidence suggests that complex spatiotemporal patterns of muscle activity can be explained with a low-dimensional set of muscle synergies or M-modes. While it is clear that both spatial and temporal aspects of muscle coordination may be low dimensional, constraints on spatial versus temporal features of muscle coordination likely involve different neural control mechanisms. We hypothesized that the low-dimensional spatial and temporal features of muscle coordination are independent of each other. We further hypothesized that in reactive feedback tasks, spatially fixed muscle coordination patterns—or muscle synergies—are hierarchically recruited via time-varying neural commands based on delayed task-level feedback. We explicitly compared the ability of spatially fixed (SF) versus temporally fixed (TF) muscle synergies to reconstruct the entire time course of muscle activity during postural responses to anterior-posterior support-surface translations. While both SF and TF muscle synergies could account for EMG variability in a postural task, SF muscle synergies produced more consistent and physiologically interpretable results than TF muscle synergies during postural responses to perturbations. Moreover, a majority of SF muscle synergies were consistent in structure when extracted from epochs throughout postural responses. Temporal patterns of SF muscle synergy recruitment were well-reconstructed by delayed feedback of center of mass (CoM) kinematics and reproduced EMG activity of multiple muscles. Consistent with the idea that independent and hierarchical low-dimensional neural control structures define spatial and temporal patterns of muscle activity, our results suggest that CoM kinematics are a task variable used to recruit SF muscle synergies for feedback control of balance. PMID:21957219

Cascadia Onshore-Offshore Site Response, Submarine Sediment Mobilization, and Earthquake Recurrence

NASA Astrophysics Data System (ADS)

Gomberg, J.

2018-02-01

Local geologic structure and topography may modify arriving seismic waves. This inherent variation in shaking, or "site response," may affect the distribution of slope failures and redistribution of submarine sediments. I used seafloor seismic data from the 2011 to 2015 Cascadia Initiative and permanent onshore seismic networks to derive estimates of site response, denoted Sn, in low- and high-frequency (0.02-1 and 1-10 Hz) passbands. For three shaking metrics (peak velocity and acceleration and energy density) Sn varies similarly throughout Cascadia and changes primarily in the direction of convergence, roughly east-west. In the two passbands, Sn patterns offshore are nearly opposite and range over an order of magnitude or more across Cascadia. Sn patterns broadly may be attributed to sediment resonance and attenuation. This and an abrupt step in the east-west trend of Sn suggest that changes in topography and structure at the edge of the continental margin significantly impact shaking. These patterns also correlate with gravity lows diagnostic of marginal basins and methane plumes channeled within shelf-bounding faults. Offshore Sn exceeds that onshore in both passbands, and the steepest slopes and shelf coincide with the relatively greatest and smallest Sn estimates at low and high frequencies, respectively; these results should be considered in submarine shaking-triggered slope stability failure studies. Significant north-south Sn variations are not apparent, but sparse sampling does not permit rejection of the hypothesis that the southerly decrease in intervals between shaking-triggered turbidites and great earthquakes inferred by Goldfinger et al. (2012, 2013, 2016) and Priest et al. (2017) is due to inherently stronger shaking southward.

Decoding Dynamic Brain Patterns from Evoked Responses: A Tutorial on Multivariate Pattern Analysis Applied to Time Series Neuroimaging Data.

PubMed

Grootswagers, Tijl; Wardle, Susan G; Carlson, Thomas A

2017-04-01

Multivariate pattern analysis (MVPA) or brain decoding methods have become standard practice in analyzing fMRI data. Although decoding methods have been extensively applied in brain-computer interfaces, these methods have only recently been applied to time series neuroimaging data such as MEG and EEG to address experimental questions in cognitive neuroscience. In a tutorial style review, we describe a broad set of options to inform future time series decoding studies from a cognitive neuroscience perspective. Using example MEG data, we illustrate the effects that different options in the decoding analysis pipeline can have on experimental results where the aim is to "decode" different perceptual stimuli or cognitive states over time from dynamic brain activation patterns. We show that decisions made at both preprocessing (e.g., dimensionality reduction, subsampling, trial averaging) and decoding (e.g., classifier selection, cross-validation design) stages of the analysis can significantly affect the results. In addition to standard decoding, we describe extensions to MVPA for time-varying neuroimaging data including representational similarity analysis, temporal generalization, and the interpretation of classifier weight maps. Finally, we outline important caveats in the design and interpretation of time series decoding experiments.

A model-based exploration of the role of pattern generating circuits during locomotor adaptation.

PubMed

Marjaninejad, Ali; Finley, James M

2016-08-01

In this study, we used a model-based approach to explore the potential contributions of central pattern generating circuits (CPGs) during adaptation to external perturbations during locomotion. We constructed a neuromechanical modeled of locomotion using a reduced-phase CPG controller and an inverted pendulum mechanical model. Two different forms of locomotor adaptation were examined in this study: split-belt treadmill adaptation and adaptation to a unilateral, elastic force field. For each simulation, we first examined the effects of phase resetting and varying the model's initial conditions on the resulting adaptation. After evaluating the effect of phase resetting on the adaptation of step length symmetry, we examined the extent to which the results from these simple models could explain previous experimental observations. We found that adaptation of step length symmetry during split-belt treadmill walking could be reproduced using our model, but this model failed to replicate patterns of adaptation observed in response to force field perturbations. Given that spinal animal models can adapt to both of these types of perturbations, our findings suggest that there may be distinct features of pattern generating circuits that mediate each form of adaptation.

Neural feedback for instantaneous spatiotemporal modulation of afferent pathways in bi-directional brain-machine interfaces.

PubMed

Liu, Jianbo; Khalil, Hassan K; Oweiss, Karim G

2011-10-01

In bi-directional brain-machine interfaces (BMIs), precisely controlling the delivery of microstimulation, both in space and in time, is critical to continuously modulate the neural activity patterns that carry information about the state of the brain-actuated device to sensory areas in the brain. In this paper, we investigate the use of neural feedback to control the spatiotemporal firing patterns of neural ensembles in a model of the thalamocortical pathway. Control of pyramidal (PY) cells in the primary somatosensory cortex (S1) is achieved based on microstimulation of thalamic relay cells through multiple-input multiple-output (MIMO) feedback controllers. This closed loop feedback control mechanism is achieved by simultaneously varying the stimulation parameters across multiple stimulation electrodes in the thalamic circuit based on continuous monitoring of the difference between reference patterns and the evoked responses of the cortical PY cells. We demonstrate that it is feasible to achieve a desired level of performance by controlling the firing activity pattern of a few "key" neural elements in the network. Our results suggest that neural feedback could be an effective method to facilitate the delivery of information to the cortex to substitute lost sensory inputs in cortically controlled BMIs.

Temporally varying relative risks for infectious diseases: implications for infectious disease control

PubMed Central

Goldstein, Edward; Pitzer, Virginia E.; O'Hagan, Justin J.; Lipsitch, Marc

2016-01-01

Risks for disease in some population groups relative to others (relative risks) are usually considered to be consistent over time, though they are often modified by other, non-temporal factors. For infectious diseases, in which overall incidence often varies substantially over time, the patterns of temporal changes in relative risks can inform our understanding of basic epidemiologic questions. For example, recent work suggests that temporal changes in relative risks of infection over the course of an epidemic cycle can both be used to identify population groups that drive infectious disease outbreaks, and help elucidate differences in the effect of vaccination against infection (that is relevant to transmission control) compared with its effect against disease episodes (that reflects individual protection). Patterns of change in the in age groups affected over the course of seasonal outbreaks can provide clues to the types of pathogens that could be responsible for diseases for which an infectious cause is suspected. Changing apparent efficacy of vaccines during trials may provide clues to the vaccine's mode of action and/or indicate risk heterogeneity in the trial population. Declining importance of unusual behavioral risk factors may be a signal of increased local transmission of an infection. We review these developments and the related public health implications. PMID:27748685

A robust operational model for predicting where tropical cyclone waves damage coral reefs

NASA Astrophysics Data System (ADS)

Puotinen, Marji; Maynard, Jeffrey A.; Beeden, Roger; Radford, Ben; Williams, Gareth J.

2016-05-01

Tropical cyclone (TC) waves can severely damage coral reefs. Models that predict where to find such damage (the ‘damage zone’) enable reef managers to: 1) target management responses after major TCs in near-real time to promote recovery at severely damaged sites; and 2) identify spatial patterns in historic TC exposure to explain habitat condition trajectories. For damage models to meet these needs, they must be valid for TCs of varying intensity, circulation size and duration. Here, we map damage zones for 46 TCs that crossed Australia’s Great Barrier Reef from 1985-2015 using three models - including one we develop which extends the capability of the others. We ground truth model performance with field data of wave damage from seven TCs of varying characteristics. The model we develop (4MW) out-performed the other models at capturing all incidences of known damage. The next best performing model (AHF) both under-predicted and over-predicted damage for TCs of various types. 4MW and AHF produce strikingly different spatial and temporal patterns of damage potential when used to reconstruct past TCs from 1985-2015. The 4MW model greatly enhances both of the main capabilities TC damage models provide to managers, and is useful wherever TCs and coral reefs co-occur.

A robust operational model for predicting where tropical cyclone waves damage coral reefs.

PubMed

Puotinen, Marji; Maynard, Jeffrey A; Beeden, Roger; Radford, Ben; Williams, Gareth J

2016-05-17

Tropical cyclone (TC) waves can severely damage coral reefs. Models that predict where to find such damage (the 'damage zone') enable reef managers to: 1) target management responses after major TCs in near-real time to promote recovery at severely damaged sites; and 2) identify spatial patterns in historic TC exposure to explain habitat condition trajectories. For damage models to meet these needs, they must be valid for TCs of varying intensity, circulation size and duration. Here, we map damage zones for 46 TCs that crossed Australia's Great Barrier Reef from 1985-2015 using three models - including one we develop which extends the capability of the others. We ground truth model performance with field data of wave damage from seven TCs of varying characteristics. The model we develop (4MW) out-performed the other models at capturing all incidences of known damage. The next best performing model (AHF) both under-predicted and over-predicted damage for TCs of various types. 4MW and AHF produce strikingly different spatial and temporal patterns of damage potential when used to reconstruct past TCs from 1985-2015. The 4MW model greatly enhances both of the main capabilities TC damage models provide to managers, and is useful wherever TCs and coral reefs co-occur.

Temporally Varying Relative Risks for Infectious Diseases: Implications for Infectious Disease Control.

PubMed

Goldstein, Edward; Pitzer, Virginia E; O'Hagan, Justin J; Lipsitch, Marc

2017-01-01

Risks for disease in some population groups relative to others (relative risks) are usually considered to be consistent over time, although they are often modified by other, nontemporal factors. For infectious diseases, in which overall incidence often varies substantially over time, the patterns of temporal changes in relative risks can inform our understanding of basic epidemiologic questions. For example, recent studies suggest that temporal changes in relative risks of infection over the course of an epidemic cycle can both be used to identify population groups that drive infectious disease outbreaks, and help elucidate differences in the effect of vaccination against infection (that is relevant to transmission control) compared with its effect against disease episodes (that reflects individual protection). Patterns of change in the age groups affected over the course of seasonal outbreaks can provide clues to the types of pathogens that could be responsible for diseases for which an infectious cause is suspected. Changing apparent efficacy of vaccines during trials may provide clues to the vaccine's mode of action and/or indicate risk heterogeneity in the trial population. Declining importance of unusual behavioral risk factors may be a signal of increased local transmission of an infection. We review these developments and the related public health implications.

Seasonally Varying Predation Behavior and Climate Shifts Are Predicted to Affect Predator-Prey Cycles.

PubMed

Tyson, Rebecca; Lutscher, Frithjof

2016-11-01

The functional response of some predator species changes from a pattern characteristic for a generalist to that for a specialist according to seasonally varying prey availability. Current theory does not address the dynamic consequences of this phenomenon. Since season length correlates strongly with altitude and latitude and is predicted to change under future climate scenarios, including this phenomenon in theoretical models seems essential for correct prediction of future ecosystem dynamics. We develop and analyze a two-season model for the great horned owl (Bubo virginialis) and snowshoe hare (Lepus americanus). These species form a predator-prey system in which the generalist to specialist shift in predation pattern has been documented empirically. We study the qualitative behavior of this predator-prey model community as summer season length changes. We find that relatively small changes in summer season length can have a profound impact on the system. In particular, when the predator has sufficient alternative resources available during the summer season, it can drive the prey to extinction, there can be coexisting stable states, and there can be stable large-amplitude limit cycles coexisting with a stable steady state. Our results illustrate that the impacts of global change on local ecosystems can be driven by internal system dynamics and can potentially have catastrophic consequences.

Sleep-wake time perception varies by direct or indirect query.

PubMed

Alameddine, Y; Ellenbogen, J M; Bianchi, M T

2015-01-15

The diagnosis of insomnia rests on self-report of difficulty initiating or maintaining sleep. However, subjective reports may be unreliable, and possibly may vary by the method of inquiry. We investigated this possibility by comparing within-individual response to direct versus indirect time queries after overnight polysomnography. We obtained self-reported sleep-wake times via morning questionnaires in 879 consecutive adult diagnostic polysomnograms. Responses were compared within subjects (direct versus indirect query) and across groups defined by apnea-hypopnea index and by self-reported insomnia symptoms in pre-sleep questionnaires. Direct queries required a time duration response, while indirect queries required clock times from which we calculated time durations. Direct and indirect queries of sleep latency were the same in only 41% of cases, and total sleep time queries matched in only 5.4%. For both latency and total sleep, the most common discrepancy involved the indirect value being larger than the direct response. The discrepancy between direct and indirect queries was not related to objective sleep metrics. The degree of discrepancy was not related to the presence of insomnia symptoms, although patients reporting insomnia symptoms showed underestimation of total sleep duration by direct response. Self-reported sleep latency and total sleep time are often internally inconsistent when comparing direct and indirect survey queries of each measure. These discrepancies represent substantive challenges to effective clinical practice, particularly when diagnosis and management depends on self-reported sleep patterns, as with insomnia. Although self-reported sleep-wake times remains fundamental to clinical practice, objective measures provide clinically relevant adjunctive information. © 2015 American Academy of Sleep Medicine.

Timeslice experiments for understanding regional climate projections: applications to the tropical hydrological cycle and European winter circulation

NASA Astrophysics Data System (ADS)

Chadwick, Robin; Douville, Hervé; Skinner, Christopher B.

2017-11-01

A set of atmosphere-only timeslice experiments are described, designed to examine the processes that cause regional climate change and inter-model uncertainty in coupled climate model responses to CO_2 forcing. The timeslice experiments are able to reproduce the pattern of regional climate change in the coupled models, and are applied here to two cases where inter-model uncertainty in future projections is large: the tropical hydrological cycle, and European winter circulation. In tropical forest regions, the plant physiological effect is the largest cause of hydrological cycle change in the two models that represent this process. This suggests that the CMIP5 ensemble mean may be underestimating the magnitude of water cycle change in these regions, due to the inclusion of models without the plant effect. SST pattern change is the dominant cause of precipitation and circulation change over the tropical oceans, and also appears to contribute to inter-model uncertainty in precipitation change over tropical land regions. Over Europe and the North Atlantic, uniform SST increases drive a poleward shift of the storm-track. However this does not consistently translate into an overall polewards storm-track shift, due to large circulation responses to SST pattern change, which varies across the models. Coupled model SST biases influence regional rainfall projections in regions such as the Maritime Continent, and so projections in these regions should be treated with caution.

How stable is activation in the amygdala and prefrontal cortex in adolescence? A study of emotional face processing across three measurements.

PubMed

van den Bulk, Bianca G; Koolschijn, P Cédric M P; Meens, Paul H F; van Lang, Natasja D J; van der Wee, Nic J A; Rombouts, Serge A R B; Vermeiren, Robert R J M; Crone, Eveline A

2013-04-01

Prior developmental functional magnetic resonance imaging (fMRI) studies have demonstrated elevated activation patterns in the amygdala and prefrontal cortex (PFC) in response to viewing emotional faces. As adolescence is a time of substantial variability in mood and emotional responsiveness, the stability of activation patterns could be fluctuating over time. In the current study, 27 healthy adolescents (age: 12-19 years) were scanned three times over a period of six months (mean test-retest interval of three months; final samples N=27, N=22, N=18). At each session, participants performed the same emotional faces task. At first measurement the presentation of emotional faces resulted in heightened activation in bilateral amygdala, bilateral lateral PFC and visual areas including the fusiform face area. Average activation did not differ across test-sessions over time, indicating that at the group level activation patterns in this network do not vary significantly over time. However, using the Intraclass Correlation Coefficient (ICC), fMRI reliability demonstrated only fair reliability for PFC (ICC=0.41-0.59) and poor reliability for the amygdala (ICC<0.4). These findings suggest substantial variability of brain activity over time and may have implications for studies investigating the influence of treatment effects on changes in neural levels in adolescents with psychiatric disorders. Copyright © 2012 Elsevier Ltd. All rights reserved.

Gene transcription patterns in response to low level petroleum contaminants in Mytilus trossulus from field sites and harbors in southcentral Alaska

USGS Publications Warehouse

Bowen, Lizabeth; Miles, A. Keith; Ballachey, Brenda E.; Waters, Shannon C.; Bodkin, James L.; Lindeberg, Mandy; Esler, Daniel N.

2017-01-01

The 1989 Exxon Valdez oil spill damaged a wide range of natural resources, including intertidal communities, and post-spill studies demonstrated acute and chronic exposure and injury to an array of species. Standard toxicological methods to evaluate petroleum contaminants have assessed tissue burdens, with fewer assays providing indicators of health or physiology, particularly when contaminant levels are low and chronic. Marine mussels are a ubiquitous and crucial component of the nearshore environment, and new genomic technologies exist to quantify molecular responses of individual mussels to stimuli, including exposure to polycyclic aromatic hydrocarbons (PAHs). We used gene-based assays of exposure and physiological function to assess chronic oil contamination using the Pacific blue mussel, Mytilus trossulus. We developed a diagnostic gene transcription panel to investigate exposure to PAHs and other contaminants and its effects on mussel physiology and health. During 2012–2015, we analyzed mussels from five field sites in western Prince William Sound, Alaska, with varying oil histories from the 1989 Exxon Valdez oil spill, and from three boat harbors in the area. Gene transcription patterns of mussels from harbors were consistent with elevated exposure to PAHs or other contaminants, whereas transcription patterns of mussels sampled from shorelines in areas affected by the oil spill indicated no PAH exposure.

Using Hierarchical Cluster Models to Systematically Identify Groups of Jobs With Similar Occupational Questionnaire Response Patterns to Assist Rule-Based Expert Exposure Assessment in Population-Based Studies

PubMed Central

Friesen, Melissa C.; Shortreed, Susan M.; Wheeler, David C.; Burstyn, Igor; Vermeulen, Roel; Pronk, Anjoeka; Colt, Joanne S.; Baris, Dalsu; Karagas, Margaret R.; Schwenn, Molly; Johnson, Alison; Armenti, Karla R.; Silverman, Debra T.; Yu, Kai

2015-01-01

Objectives: Rule-based expert exposure assessment based on questionnaire response patterns in population-based studies improves the transparency of the decisions. The number of unique response patterns, however, can be nearly equal to the number of jobs. An expert may reduce the number of patterns that need assessment using expert opinion, but each expert may identify different patterns of responses that identify an exposure scenario. Here, hierarchical clustering methods are proposed as a systematic data reduction step to reproducibly identify similar questionnaire response patterns prior to obtaining expert estimates. As a proof-of-concept, we used hierarchical clustering methods to identify groups of jobs (clusters) with similar responses to diesel exhaust-related questions and then evaluated whether the jobs within a cluster had similar (previously assessed) estimates of occupational diesel exhaust exposure. Methods: Using the New England Bladder Cancer Study as a case study, we applied hierarchical cluster models to the diesel-related variables extracted from the occupational history and job- and industry-specific questionnaires (modules). Cluster models were separately developed for two subsets: (i) 5395 jobs with ≥1 variable extracted from the occupational history indicating a potential diesel exposure scenario, but without a module with diesel-related questions; and (ii) 5929 jobs with both occupational history and module responses to diesel-relevant questions. For each subset, we varied the numbers of clusters extracted from the cluster tree developed for each model from 100 to 1000 groups of jobs. Using previously made estimates of the probability (ordinal), intensity (µg m−3 respirable elemental carbon), and frequency (hours per week) of occupational exposure to diesel exhaust, we examined the similarity of the exposure estimates for jobs within the same cluster in two ways. First, the clusters’ homogeneity (defined as >75% with the same estimate) was examined compared to a dichotomized probability estimate (<5 versus ≥5%; <50 versus ≥50%). Second, for the ordinal probability metric and continuous intensity and frequency metrics, we calculated the intraclass correlation coefficients (ICCs) between each job’s estimate and the mean estimate for all jobs within the cluster. Results: Within-cluster homogeneity increased when more clusters were used. For example, ≥80% of the clusters were homogeneous when 500 clusters were used. Similarly, ICCs were generally above 0.7 when ≥200 clusters were used, indicating minimal within-cluster variability. The most within-cluster variability was observed for the frequency metric (ICCs from 0.4 to 0.8). We estimated that using an expert to assign exposure at the cluster-level assignment and then to review each job in non-homogeneous clusters would require ~2000 decisions per expert, in contrast to evaluating 4255 unique questionnaire patterns or 14983 individual jobs. Conclusions: This proof-of-concept shows that using cluster models as a data reduction step to identify jobs with similar response patterns prior to obtaining expert ratings has the potential to aid rule-based assessment by systematically reducing the number of exposure decisions needed. While promising, additional research is needed to quantify the actual reduction in exposure decisions and the resulting homogeneity of exposure estimates within clusters for an exposure assessment effort that obtains cluster-level expert assessments as part of the assessment process. PMID:25477475

Using hierarchical cluster models to systematically identify groups of jobs with similar occupational questionnaire response patterns to assist rule-based expert exposure assessment in population-based studies.

PubMed

Friesen, Melissa C; Shortreed, Susan M; Wheeler, David C; Burstyn, Igor; Vermeulen, Roel; Pronk, Anjoeka; Colt, Joanne S; Baris, Dalsu; Karagas, Margaret R; Schwenn, Molly; Johnson, Alison; Armenti, Karla R; Silverman, Debra T; Yu, Kai

2015-05-01

Rule-based expert exposure assessment based on questionnaire response patterns in population-based studies improves the transparency of the decisions. The number of unique response patterns, however, can be nearly equal to the number of jobs. An expert may reduce the number of patterns that need assessment using expert opinion, but each expert may identify different patterns of responses that identify an exposure scenario. Here, hierarchical clustering methods are proposed as a systematic data reduction step to reproducibly identify similar questionnaire response patterns prior to obtaining expert estimates. As a proof-of-concept, we used hierarchical clustering methods to identify groups of jobs (clusters) with similar responses to diesel exhaust-related questions and then evaluated whether the jobs within a cluster had similar (previously assessed) estimates of occupational diesel exhaust exposure. Using the New England Bladder Cancer Study as a case study, we applied hierarchical cluster models to the diesel-related variables extracted from the occupational history and job- and industry-specific questionnaires (modules). Cluster models were separately developed for two subsets: (i) 5395 jobs with ≥1 variable extracted from the occupational history indicating a potential diesel exposure scenario, but without a module with diesel-related questions; and (ii) 5929 jobs with both occupational history and module responses to diesel-relevant questions. For each subset, we varied the numbers of clusters extracted from the cluster tree developed for each model from 100 to 1000 groups of jobs. Using previously made estimates of the probability (ordinal), intensity (µg m(-3) respirable elemental carbon), and frequency (hours per week) of occupational exposure to diesel exhaust, we examined the similarity of the exposure estimates for jobs within the same cluster in two ways. First, the clusters' homogeneity (defined as >75% with the same estimate) was examined compared to a dichotomized probability estimate (<5 versus ≥5%; <50 versus ≥50%). Second, for the ordinal probability metric and continuous intensity and frequency metrics, we calculated the intraclass correlation coefficients (ICCs) between each job's estimate and the mean estimate for all jobs within the cluster. Within-cluster homogeneity increased when more clusters were used. For example, ≥80% of the clusters were homogeneous when 500 clusters were used. Similarly, ICCs were generally above 0.7 when ≥200 clusters were used, indicating minimal within-cluster variability. The most within-cluster variability was observed for the frequency metric (ICCs from 0.4 to 0.8). We estimated that using an expert to assign exposure at the cluster-level assignment and then to review each job in non-homogeneous clusters would require ~2000 decisions per expert, in contrast to evaluating 4255 unique questionnaire patterns or 14983 individual jobs. This proof-of-concept shows that using cluster models as a data reduction step to identify jobs with similar response patterns prior to obtaining expert ratings has the potential to aid rule-based assessment by systematically reducing the number of exposure decisions needed. While promising, additional research is needed to quantify the actual reduction in exposure decisions and the resulting homogeneity of exposure estimates within clusters for an exposure assessment effort that obtains cluster-level expert assessments as part of the assessment process. Published by Oxford University Press on behalf of the British Occupational Hygiene Society 2014.

Seasonal changes in the body size of two rotifer species living in activated sludge follow the Temperature-Size Rule.

PubMed

Kiełbasa, Anna; Walczyńska, Aleksandra; Fiałkowska, Edyta; Pajdak-Stós, Agnieszka; Kozłowski, Jan

2014-12-01

Temperature-Size Rule (TSR) is a phenotypic body size response of ectotherms to changing temperature. It is known from the laboratory studies, but seasonal patterns in the field were not studied so far. We examined the body size changes in time of rotifers inhabiting activated sludge. We hypothesize that temperature is the most influencing parameter in sludge environment, leading sludge rotifers to seasonally change their body size according to TSR, and that oxygen content also induces the size response. The presence of TSR in Lecane inermis rotifer was tested in a laboratory study with two temperature and two food-type treatments. The effect of interaction between temperature and food was significant; L. inermis followed TSR in one food type only. The seasonal variability in the body sizes of the rotifers L. inermis and Cephalodella gracilis was estimated by monthly sampling and analyzed by multiple regression, in relation to the sludge parameters selected as the most influential by multivariate analysis, and predicted to alter rotifer body size (temperature and oxygen). L. inermis varied significantly in size throughout the year, and this variability is explained by temperature as predicted by the TSR, but not by oxygen availability. C. gracilis also varied in size, though this variability was explained by both temperature and oxygen. We suggest that sludge age acts as a mortality factor in activated sludge. It may have a seasonal effect on the body size of L. inermis and modify a possible effect of oxygen. Activated sludge habitat is driven by both biological processes and human regulation, yet its resident organisms follow general evolutionary rule as they do in other biological systems. The interspecific response patterns differ, revealing the importance of taking species-specific properties into account. Our findings are applicable to sludge properties enhancement through optimizing the conditions for its biological component.

20 Meter Solar Sail Analysis and Correlation

NASA Technical Reports Server (NTRS)

Taleghani, B.; Lively, P.; Banik, J.; Murphy, D.; Trautt, T.

2005-01-01

This presentation discusses studies conducted to determine the element type and size that best represents a 20-meter solar sail under ground-test load conditions, the performance of test/Analysis correlation by using Static Shape Optimization Method for Q4 sail, and system dynamic. TRIA3 elements better represent wrinkle patterns than do QUAD3 elements Baseline, ten-inch elements are small enough to accurately represent sail shape, and baseline TRIA3 mesh requires a reasonable computation time of 8 min. 21 sec. In the test/analysis correlation by using Static shape optimization method for Q4 sail, ten parameters were chosen and varied during optimization. 300 sail models were created with random parameters. A response surfaces for each targets which were created based on the varied parameters. Parameters were optimized based on response surface. Deflection shape comparison for 0 and 22.5 degrees yielded a 4.3% and 2.1% error respectively. For the system dynamic study testing was done on the booms without the sails attached. The nominal boom properties produced a good correlation to test data the frequencies were within 10%. Boom dominated analysis frequencies and modes compared well with the test results.

Developmental differences in the neural mechanisms of facial emotion labeling.

PubMed

Wiggins, Jillian Lee; Adleman, Nancy E; Kim, Pilyoung; Oakes, Allison H; Hsu, Derek; Reynolds, Richard C; Chen, Gang; Pine, Daniel S; Brotman, Melissa A; Leibenluft, Ellen

2016-01-01

Adolescence is a time of increased risk for the onset of psychological disorders associated with deficits in face emotion labeling. We used functional magnetic resonance imaging (fMRI) to examine age-related differences in brain activation while adolescents and adults labeled the emotion on fearful, happy and angry faces of varying intensities [0% (i.e. neutral), 50%, 75%, 100%]. Adolescents and adults did not differ on accuracy to label emotions. In the superior temporal sulcus, ventrolateral prefrontal cortex and middle temporal gyrus, adults show an inverted-U-shaped response to increasing intensities of fearful faces and a U-shaped response to increasing intensities of happy faces, whereas adolescents show the opposite patterns. In addition, adults, but not adolescents, show greater inferior occipital gyrus activation to negative (angry, fearful) vs positive (happy) emotions. In sum, when subjects classify subtly varying facial emotions, developmental differences manifest in several 'ventral stream' brain regions. Charting the typical developmental course of the brain mechanisms of socioemotional processes, such as facial emotion labeling, is an important focus for developmental psychopathology research. Published by Oxford University Press 2015. This work is written by US Government employees and is in the public domain in the US.

The relationship between direct predation and antipredator responses: a test with multiple predators and multiple prey.

PubMed

Creel, Scott; Dröge, Egil; M'soka, Jassiel; Smit, Daan; Becker, Matt; Christianson, Dave; Schuette, Paul

2017-08-01

Most species adjust their behavior to reduce the likelihood of predation. Many experiments have shown that antipredator responses carry energetic costs that can affect growth, survival, and reproduction, so that the total cost of predation depends on a trade-off between direct predation and risk effects. Despite these patterns, few field studies have examined the relationship between direct predation and the strength of antipredator responses, particularly for complete guilds of predators and prey. We used scan sampling in 344 observation periods over a four-year field study to examine behavioral responses to the immediate presence of predators for a complete antelope guild (dominated by wildebeest, zebra, and oribi) in Liuwa Plains National Park, Zambia, testing for differences in response to all large carnivores in the ecosystem (lions, spotted hyenas, cheetahs, and African wild dogs). We quantified the proportion that each prey species contributed to the kills made by each predator (516 total kills), used distance sampling on systematic line transects to determine the abundance of each prey species, and combined these data to quantify the per-capita risk of direct predation for each predator-prey pair. On average, antelopes increased their vigilance by a factor of 2.4 when predators were present. Vigilance varied strongly among prey species, but weakly in response to different predators. Increased vigilance was correlated with reduced foraging in a similar manner for all prey species. The strength of antipredator response was not detectably related to patterns of direct predation (n = 15 predator-prey combinations with sufficient data). This lack of correlation has implications for our understanding of the role of risk effects as part of the limiting effect of predators on prey. © 2017 by the Ecological Society of America.

L-Amino Acids Elicit Diverse Response Patterns in Taste Sensory Cells: A Role for Multiple Receptors

PubMed Central

Pal Choudhuri, Shreoshi; Delay, Rona J.; Delay, Eugene R.

2015-01-01

Umami, the fifth basic taste, is elicited by the L-amino acid, glutamate. A unique characteristic of umami taste is the response potentiation by 5’ ribonucleotide monophosphates, which are also capable of eliciting an umami taste. Initial reports using human embryonic kidney (HEK) cells suggested that there is one broadly tuned receptor heterodimer, T1r1+T1r3, which detects L-glutamate and all other L-amino acids. However, there is growing evidence that multiple receptors detect glutamate in the oral cavity. While much is understood about glutamate transduction, the mechanisms for detecting the tastes of other L-amino acids are less well understood. We used calcium imaging of isolated taste sensory cells and taste cell clusters from the circumvallate and foliate papillae of C57BL/6J and T1r3 knockout mice to determine if other receptors might also be involved in detection of L-amino acids. Ratiometric imaging with Fura-2 was used to study calcium responses to monopotassium L-glutamate, L-serine, L-arginine, and L-glutamine, with and without inosine 5’ monophosphate (IMP). The results of these experiments showed that the response patterns elicited by L-amino acids varied significantly across taste sensory cells. L-amino acids other than glutamate also elicited synergistic responses in a subset of taste sensory cells. Along with its role in synergism, IMP alone elicited a response in a large number of taste sensory cells. Our data indicate that synergistic and non-synergistic responses to L-amino acids and IMP are mediated by multiple receptors or possibly a receptor complex. PMID:26110622

Electric field induced microstructures in thin films on physicochemically heterogeneous and patterned substrates.

PubMed

Srivastava, Samanvaya; Reddy, P Dinesh Sankar; Wang, Cindy; Bandyopadhyay, Dipankar; Sharma, Ashutosh

2010-05-07

We study by nonlinear simulations the electric field induced pattern formation in a thin viscous film resting on a topographically or chemically patterned substrate. The thin film microstructures can be aligned to the substrate patterns within a window of parameters where the spinodal length scale of the field induced instability is close to the substrate periodicity. We investigate systematically the change in the film morphology and order when (i) the substrate pattern periodicity is varied at a constant film thickness and (ii) the film thickness is varied at a constant substrate periodicity. Simulations show two distinct pathway of evolution when the substrate-topography changes from protrusions to cavities. The isolated substrate defects generate locally ordered ripplelike structures distinct from the structures on a periodically patterned substrate. In the latter case, film morphology is governed by a competition between the pattern periodicity and the length scale of instability. Relating the thin film morphologies to the underlying substrate pattern has implications for field induced patterning and robustness of inter-interface pattern transfer, e.g., coding-decoding of information printed on a substrate.

Effects of convection patterns on freckle formation of directionally solidified Nickel-based superalloy casting with abruptly varying cross-sections

NASA Astrophysics Data System (ADS)

Qin, Ling; Shen, Jun; Li, Qiudong; Shang, Zhao

2017-05-01

The effects of convection patterns on freckle formation of directionally solidified Nickel-based superalloy sample with abruptly varying cross-sections were investigated experimentally and numerically. The experimental results demonstrate that freckles were only observed at the bottom of larger cross-section. Numerical results indicate that this phenomenon should be attributed to the different convection patterns at front of solidification interface. As the withdrawal rate increased, the primary dendrites spacing has an obvious influence on freckle formation. A more in-depth investigation of the convection patterns can provide a better understanding of freckle formation and perhaps offer methods to minimize freckles in turbine blades.

Modeling and predictions of biphasic mechanosensitive cell migration altered by cell-intrinsic properties and matrix confinement.

PubMed

Pathak, Amit

2018-04-12

Motile cells sense the stiffness of their extracellular matrix (ECM) through adhesions and respond by modulating the generated forces, which in turn lead to varying mechanosensitive migration phenotypes. Through modeling and experiments, cell migration speed is known to vary with matrix stiffness in a biphasic manner, with optimal motility at an intermediate stiffness. Here, we present a two-dimensional cell model defined by nodes and elements, integrated with subcellular modeling components corresponding to mechanotransductive adhesion formation, force generation, protrusions and node displacement. On 2D matrices, our calculations reproduce the classic biphasic dependence of migration speed on matrix stiffness and predict that cell types with higher force-generating ability do not slow down on very stiff matrices, thus disabling the biphasic response. We also predict that cell types defined by lower number of total receptors require stiffer matrices for optimal motility, which also limits the biphasic response. For a cell type with robust biphasic migration on 2D surface, simulations in channel-like confined environments of varying width and height predict faster migration in more confined matrices. Simulations performed in shallower channels predict that the biphasic mechanosensitive cell migration response is more robust on 2D micro-patterns as compared to the channel-like 3D confinement. Thus, variations in the dimensionality of matrix confinement alters the way migratory cells sense and respond to the matrix stiffness. Our calculations reveal new phenotypes of stiffness- and topography-sensitive cell migration that critically depend on both cell-intrinsic and matrix properties. These predictions may inform our understanding of various mechanosensitive modes of cell motility that could enable tumor invasion through topographically heterogeneous microenvironments. © 2018 IOP Publishing Ltd.

Depth-of-interaction estimates in pixelated scintillator sensors using Monte Carlo techniques

NASA Astrophysics Data System (ADS)

Sharma, Diksha; Sze, Christina; Bhandari, Harish; Nagarkar, Vivek; Badano, Aldo

2017-01-01

Image quality in thick scintillator detectors can be improved by minimizing parallax errors through depth-of-interaction (DOI) estimation. A novel sensor for low-energy single photon imaging having a thick, transparent, crystalline pixelated micro-columnar CsI:Tl scintillator structure has been described, with possible future application in small-animal single photon emission computed tomography (SPECT) imaging when using thicker structures under development. In order to understand the fundamental limits of this new structure, we introduce cartesianDETECT2, an open-source optical transport package that uses Monte Carlo methods to obtain estimates of DOI for improving spatial resolution of nuclear imaging applications. Optical photon paths are calculated as a function of varying simulation parameters such as columnar surface roughness, bulk, and top-surface absorption. We use scanning electron microscope images to estimate appropriate surface roughness coefficients. Simulation results are analyzed to model and establish patterns between DOI and photon scattering. The effect of varying starting locations of optical photons on the spatial response is studied. Bulk and top-surface absorption fractions were varied to investigate their effect on spatial response as a function of DOI. We investigated the accuracy of our DOI estimation model for a particular screen with various training and testing sets, and for all cases the percent error between the estimated and actual DOI over the majority of the detector thickness was ±5% with a maximum error of up to ±10% at deeper DOIs. In addition, we found that cartesianDETECT2 is computationally five times more efficient than MANTIS. Findings indicate that DOI estimates can be extracted from a double-Gaussian model of the detector response. We observed that our model predicts DOI in pixelated scintillator detectors reasonably well.

Urban Tree Species Show the Same Hydraulic Response to Vapor Pressure Deficit across Varying Tree Size and Environmental Conditions

PubMed Central

Chen, Lixin; Zhang, Zhiqiang; Ewers, Brent E.

2012-01-01

Background The functional convergence of tree transpiration has rarely been tested for tree species growing under urban conditions even though it is of significance to elucidate the relationship between functional convergence and species differences of urban trees for establishing sustainable urban forests in the context of forest water relations. Methodology/Principal Findings We measured sap flux of four urban tree species including Cedrus deodara, Zelkova schneideriana, Euonymus bungeanus and Metasequoia glyptostroboides in an urban park by using thermal dissipation probes (TDP). The concurrent microclimate conditions and soil moisture content were also measured. Our objectives were to examine 1) the influence of tree species and size on transpiration, and 2) the hydraulic control of urban trees under different environmental conditions over the transpiration in response to VPD as represented by canopy conductance. The results showed that the functional convergence between tree diameter at breast height (DBH) and tree canopy transpiration amount (E c) was not reliable to predict stand transpiration and there were species differences within same DBH class. Species differed in transpiration patterns to seasonal weather progression and soil water stress as a result of varied sensitivity to water availability. Species differences were also found in their potential maximum transpiration rate and reaction to light. However, a same theoretical hydraulic relationship between G c at VPD = 1 kPa (G cref) and the G c sensitivity to VPD (−dG c/dlnVPD) across studied species as well as under contrasting soil water and R s conditions in the urban area. Conclusions/Significance We concluded that urban trees show the same hydraulic regulation over response to VPD across varying tree size and environmental conditions and thus tree transpiration could be predicted with appropriate assessment of G cref. PMID:23118904

Urban tree species show the same hydraulic response to vapor pressure deficit across varying tree size and environmental conditions.

PubMed

Chen, Lixin; Zhang, Zhiqiang; Ewers, Brent E

2012-01-01

The functional convergence of tree transpiration has rarely been tested for tree species growing under urban conditions even though it is of significance to elucidate the relationship between functional convergence and species differences of urban trees for establishing sustainable urban forests in the context of forest water relations. We measured sap flux of four urban tree species including Cedrus deodara, Zelkova schneideriana, Euonymus bungeanus and Metasequoia glyptostroboides in an urban park by using thermal dissipation probes (TDP). The concurrent microclimate conditions and soil moisture content were also measured. Our objectives were to examine 1) the influence of tree species and size on transpiration, and 2) the hydraulic control of urban trees under different environmental conditions over the transpiration in response to VPD as represented by canopy conductance. The results showed that the functional convergence between tree diameter at breast height (DBH) and tree canopy transpiration amount (E(c)) was not reliable to predict stand transpiration and there were species differences within same DBH class. Species differed in transpiration patterns to seasonal weather progression and soil water stress as a result of varied sensitivity to water availability. Species differences were also found in their potential maximum transpiration rate and reaction to light. However, a same theoretical hydraulic relationship between G(c) at VPD = 1 kPa (G(cref)) and the G(c) sensitivity to VPD (-dG(c)/dlnVPD) across studied species as well as under contrasting soil water and R(s) conditions in the urban area. We concluded that urban trees show the same hydraulic regulation over response to VPD across varying tree size and environmental conditions and thus tree transpiration could be predicted with appropriate assessment of G(cref).

Trait coordination, mechanical behaviour and growth form plasticity of Amborella trichopoda under variation in canopy openness

PubMed Central

Trueba, Santiago; Isnard, Sandrine; Barthélémy, Daniel; Olson, Mark E.

2016-01-01

Understanding the distribution of traits across the angiosperm phylogeny helps map the nested hierarchy of features that characterize key nodes. Finding that Amborella is sister to the rest of the angiosperms has raised the question of whether it shares certain key functional trait characteristics, and plastic responses apparently widespread within the angiosperms at large. With this in mind, we test the hypothesis that local canopy openness induces plastic responses. We used this variation in morphological and functional traits to estimate the pervasiveness of trait scaling and leaf and stem economics. We studied the architecture of Amborella and how it varies under different degrees of canopy openness. We analyzed the coordination of 12 leaf and stem structural and functional traits, and the association of this covariation with differing morphologies. The Amborella habit is made up of a series of sympodial modules that vary in size and branching pattern under different canopy openness. Amborella stems vary from self-supporting to semi-scandent. Changes in stem elongation and leaf size in Amborella produce distinct morphologies under different light environments. Correlations were found between most leaf and stem functional traits. Stem tissue rigidity decreased with increasing canopy openness. Despite substantial modulation of leaf size and leaf mass per area by light availability, branches in different light environments had similar leaf area-stem size scaling. The sympodial growth observed in Amborella could point to an angiosperm synapomorphy. Our study provides evidence of intraspecific coordination between leaf and stem economic spectra. Trait variation along these spectra is likely adaptive under different light environments and is consistent with these plastic responses having been present in the angiosperm common ancestor. PMID:27672131

Deconfounding the effects of local element spatial heterogeneity and sparsity on processing dominance.

PubMed

Montoro, Pedro R; Luna, Dolores

2009-10-01

Previous studies on the processing of hierarchical patterns (Luna & Montoro, 2008) have shown that altering the spatial relationships between the local elements affected processing dominance by decreasing global advantage. In the present article, the authors examine whether heterogeneity or a sparse distribution of the local elements was the responsible factor for this effect. In Experiments 1 and 2, the distance between the local elements was increased in a similar way, but between-element distance was homogeneous in Experiment 1 and heterogeneous in Experiment 2. In Experiment 3, local elements' size was varied by presenting global patterns composed of similar large or small local elements and of different large and small sizes. The results of the present research showed that, instead of element sparsity, spatial heterogeneity that could change the appearance of the global form as well as the salience of the local elements was the main determiner of impairing global processing.

Competition between relatives and the evolution of dispersal in a parasitoid wasp

PubMed Central

INNOCENT, T. M.; ABE, J.; WEST, S. A.; REECE, S. E.

2014-01-01

Evolutionary theory predicts that levels of dispersal vary in response to the extent of local competition for resources and the relatedness between potential competitors. Here, we test these predictions by making use of a female dispersal dimorphism in the parasitoid wasp Melittobia australica. We show that there are two distinct female morphs, which differ in morphology, pattern of egg production, and dispersal behaviour. As predicted by theory, we found that greater competition for resources resulted in increased production of dispersing females. In contrast, we did not find support for the prediction that high relatedness between competitors increases the production of dispersing females in Melittobia. Finally, we exploit the close links between the evolutionary processes leading to selection for dispersal and for biased sex ratios to examine whether the pattern of dispersal can help distinguish between competing hypotheses for the lack of sex ratio adjustment in Melittobia. PMID:20492084

A cross-language study of perception of lexical stress in English.

PubMed

Yu, Vickie Y; Andruski, Jean E

2010-08-01

This study investigates the question of whether language background affects the perception of lexical stress in English. Thirty native English speakers and 30 native Chinese learners of English participated in a stressed-syllable identification task and a discrimination task involving three types of stimuli (real words/pseudowords/hums). The results show that both language groups were able to identify and discriminate stress patterns. Lexical and segmental information affected the English and Chinese speakers in varying degrees. English and Chinese speakers showed different response patterns to trochaic vs. iambic stress across the three types of stimuli. An acoustic analysis revealed that two language groups used different acoustic cues to process lexical stress. The findings suggest that the different degrees of lexical and segmental effects can be explained by language background, which in turn supports the hypothesis that language background affects the perception of lexical stress in English.

New discoveries in the pathogenesis and classification of vitiligo.

PubMed

Rodrigues, Michelle; Ezzedine, Khaled; Hamzavi, Iltefat; Pandya, Amit G; Harris, John E

2017-07-01

Vitiligo is a common autoimmune disease that progressively destroys melanocytes in the skin, resulting in the appearance of patchy depigmentation. This disfiguring condition frequently affects the face and other visible areas of the body, which can be psychologically devastating. The onset of vitiligo often occurs in younger individuals and progresses for life, resulting in a heavy burden of disease and decreased quality of life. Presentation patterns of vitiligo vary, and recognition of these patterns provides both diagnostic and prognostic clues. Recent insights into disease pathogenesis offer a better understanding of the natural history of the disease, its associations, and potential for future treatments. The first article in this continuing medical education series outlines typical and atypical presentations of vitiligo, how they reflect disease activity, prognosis, and response to treatment. Finally, we discuss disease associations, risk factors, and our current understanding of disease pathogenesis. Copyright © 2016 American Academy of Dermatology, Inc. All rights reserved.

Light and Nutrient Dependent Responses in Secondary Metabolites of Plantago lanceolata Offspring Are Due to Phenotypic Plasticity in Experimental Grasslands

PubMed Central

Miehe-Steier, Annegret; Roscher, Christiane; Reichelt, Michael; Gershenzon, Jonathan; Unsicker, Sybille B.

2015-01-01

A few studies in the past have shown that plant diversity in terms of species richness and functional composition can modify plant defense chemistry. However, it is not yet clear to what extent genetic differentiation of plant chemotypes or phenotypic plasticity in response to diversity-induced variation in growth conditions or a combination of both is responsible for this pattern. We collected seed families of ribwort plantain (Plantago lanceolata) from six-year old experimental grasslands of varying plant diversity (Jena Experiment). The offspring of these seed families was grown under standardized conditions with two levels of light and nutrients. The iridoid glycosides, catalpol and aucubin, and verbascoside, a caffeoyl phenylethanoid glycoside, were measured in roots and shoots. Although offspring of different seed families differed in the tissue concentrations of defensive metabolites, plant diversity in the mothers' environment did not explain the variation in the measured defensive metabolites of P. lanceolata offspring. However secondary metabolite levels in roots and shoots were strongly affected by light and nutrient availability. Highest concentrations of iridoid glycosides and verbascoside were found under high light conditions, and nutrient availability had positive effects on iridoid glycoside concentrations in plants grown under high light conditions. However, verbascoside concentrations decreased under high levels of nutrients irrespective of light. The data from our greenhouse study show that phenotypic plasticity in response to environmental variation rather than genetic differentiation in response to plant community diversity is responsible for variation in secondary metabolite concentrations of P. lanceolata in the six-year old communities of the grassland biodiversity experiment. Due to its large phenotypic plasticity P. lanceolata has the potential for a fast and efficient adjustment to varying environmental conditions in plant communities of different species richness and functional composition. PMID:26336100

Lg attenuation, frequency dependence and relative site response of the western United States as revealed by the EarthScope Transportable Array

NASA Astrophysics Data System (ADS)

Gallegos, Andrea; Ranasinghe, Nishath; Ni, James; Sandvol, Eric

2017-06-01

Lg attenuation of the western United States is estimated using regional waveforms recorded by EarthScope's Transportable Array, the Berkeley Digital Seismograph Network and the Caltech Regional Seismic Network. Lg attenuation is determined using the two-station method (TSM). 292 events ranging from magnitude 4 to 6.5 in a time range for the years between 2005 and 2010 are used. We have tomographically mapped variations in effective Lg Q at narrow bands with central frequencies of 0.5, 1, 2 and 3 Hz. The relative site responses of individual stations are determined using a reverse TSM at these central frequencies. Both the two-station and reverse TSMs have the advantage of effectively removing site and source effects without requiring a priori models while mapping lateral heterogeneities in the crust. Regions of high attenuation are found along the Snake River Plain, along the northern California-Oregon border, throughout the Basin and Range, Walker Lane, Wasatch Fault and the Rio Grande Rift. Regions of low attenuation are found in the Colorado Plateau, Rocky Mountains, central Nevada and the Columbia Plateau. Overall, Lg Q was found to have a power-law frequency dependence, with an increase in central frequency resulting in an increase in Q. Relative site responses were found to vary strongly with local geology. Hard rock areas such as the Sierra Nevada Mountains and the Snake River Plain show a consistent pattern of negative site response (i.e. deamplification), while areas with a higher degree of sediments, such as the grabens of the Basin and Range, show positive site response (i.e. amplification). Finally, site responses were found to vary with frequency, becoming less variable and more pronounced as frequency increases.

Time-Varying Networks of Inter-Ictal Discharging Reveal Epileptogenic Zone.

PubMed

Zhang, Luyan; Liang, Yi; Li, Fali; Sun, Hongbin; Peng, Wenjing; Du, Peishan; Si, Yajing; Song, Limeng; Yu, Liang; Xu, Peng

2017-01-01

The neuronal synchronous discharging may cause an epileptic seizure. Currently, most of the studies conducted to investigate the mechanism of epilepsy are based on EEGs or functional magnetic resonance imaging (fMRI) recorded during the ictal discharging or the resting-state, and few studies have probed into the dynamic patterns during the inter-ictal discharging that are much easier to record in clinical applications. Here, we propose a time-varying network analysis based on adaptive directed transfer function to uncover the dynamic brain network patterns during the inter-ictal discharging. In addition, an algorithm based on the time-varying outflow of information derived from the network analysis is developed to detect the epileptogenic zone. The analysis performed revealed the time-varying network patterns during different stages of inter-ictal discharging; the epileptogenic zone was activated prior to the discharge onset then worked as the source to propagate the activity to other brain regions. Consistence between the epileptogenic zones detected by our proposed approach and the actual epileptogenic zones proved that time-varying network analysis could not only reveal the underlying neural mechanism of epilepsy, but also function as a useful tool in detecting the epileptogenic zone based on the EEGs in the inter-ictal discharging.

Decoding the neural signatures of emotions expressed through sound.

PubMed

Sachs, Matthew E; Habibi, Assal; Damasio, Antonio; Kaplan, Jonas T

2018-07-01

Effective social functioning relies in part on the ability to identify emotions from auditory stimuli and respond appropriately. Previous studies have uncovered brain regions engaged by the affective information conveyed by sound. But some of the acoustical properties of sounds that express certain emotions vary remarkably with the instrument used to produce them, for example the human voice or a violin. Do these brain regions respond in the same way to different emotions regardless of the sound source? To address this question, we had participants (N = 38, 20 females) listen to brief audio excerpts produced by the violin, clarinet, and human voice, each conveying one of three target emotions-happiness, sadness, and fear-while brain activity was measured with fMRI. We used multivoxel pattern analysis to test whether emotion-specific neural responses to the voice could predict emotion-specific neural responses to musical instruments and vice-versa. A whole-brain searchlight analysis revealed that patterns of activity within the primary and secondary auditory cortex, posterior insula, and parietal operculum were predictive of the affective content of sound both within and across instruments. Furthermore, classification accuracy within the anterior insula was correlated with behavioral measures of empathy. The findings suggest that these brain regions carry emotion-specific patterns that generalize across sounds with different acoustical properties. Also, individuals with greater empathic ability have more distinct neural patterns related to perceiving emotions. These results extend previous knowledge regarding how the human brain extracts emotional meaning from auditory stimuli and enables us to understand and connect with others effectively. Copyright © 2018 Elsevier Inc. All rights reserved.

Complexities of gene expression patterns in natural populations of an extremophile fish (Poecilia mexicana, Poeciliidae)

PubMed Central

Passow, Courtney N.; Brown, Anthony P.; Arias-Rodriguez, Lenin; Yee, Muh-Ching; Sockell, Alexandra; Schartl, Manfred; Warren, Wesley C.; Bustamante, Carlos; Kelley, Joanna L.; Tobler, Michael

2017-01-01

Variation in gene expression can provide insights into organismal responses to environmental stress and physiological mechanisms mediating adaptation to habitats with contrasting environmental conditions. We performed an RNA-sequencing experiment to quantify gene expression patterns in fish adapted to habitats with different combinations of environmental stressors, including the presence of toxic hydrogen sulphide (H2S) and the absence of light in caves. We specifically asked how gene expression varies among populations living in different habitats, whether population differences were consistent among organs, and whether there is evidence for shared expression responses in populations exposed to the same stressors. We analysed organ-specific transcriptome-wide data from four ecotypes of Poecilia mexicana (nonsulphidic surface, sulphidic surface, nonsulphidic cave and sulphidic cave). The majority of variation in gene expression was correlated with organ type, and the presence of specific environmental stressors elicited unique expression differences among organs. Shared patterns of gene expression between populations exposed to the same environmental stressors increased with levels of organismal organization (from transcript to gene to physiological pathway). In addition, shared patterns of gene expression were more common between populations from sulphidic than populations from cave habitats, potentially indicating that physiochemical stressors with clear biochemical consequences can constrain the diversity of adaptive solutions that mitigate their adverse effects. Overall, our analyses provided insights into transcriptional variation in a unique system, in which adaptation to H2S and darkness coincide. Functional annotations of differentially expressed genes provide a springboard for investigating physiological mechanisms putatively underlying adaptation to extreme environments. PMID:28598519

Growth pattern of the surface of fungus Aspergillus colony

NASA Astrophysics Data System (ADS)

Matsuura, Shu; Miyazima, Sasuke

1992-05-01

Aspergillus oryzae colonies were grown under various glucose concentrations, temperatures, and agar concentrations, and the effects on the pattern were investigated. Patterns of colony were found to vary from uniform to diffusion-limited aggregation type.

Variation of radiative forcings and global warming potentials from regional aviation NOx emissions

NASA Astrophysics Data System (ADS)

Skowron, Agnieszka; Lee, David S.; De León, Ruben R.

2015-03-01

The response to hemispherical and regional aircraft NOx emissions is explored by using two climate metrics: radiative forcing (RF) and Global Warming Potential (GWP). The global chemistry transport model, MOZART-3 CTM, is applied in this study for a series of incremental aircraft NOx emission integrations to different regions. It was found that the sensitivity of chemical responses per unit emission rate from regional aircraft NOx emissions varies with size of aircraft NOx emission rate and that climate metric values decrease with increasing aircraft NOx emission rates, except for Southeast Asia. Previous work has recognized that aircraft NOx GWPs may vary regionally. However, the way in which these regional GWPs are calculated are critical. Previous studies have added a fixed amount of NOx to different regions. This approach can heavily bias the results of a regional GWP because of the well-established sensitivity of O3 production to background NOx whereby the Ozone Production Efficiency (OPE) is greater at small background NOx. Thus, even a small addition of NOx in a clean-air area can produce a large O3 response. Using this 'fixed addition' method of 0.035 Tg(N) yr-1, results in the greatest effect observed for North Atlantic and Brazil, ∼10.0 mW m-2/Tg(N) yr-1. An alternative 'proportional approach' is also taken that preserves the subtle balance of local NOx-O3-CH4 systems with the existing emission patterns of aircraft and background NOx, whereby a proportional amount of aircraft NOx, 5% (N) yr-1, is added to each region in order to determine the response. This results in the greatest effect observed for North Pacific that with its net NOx RF of 23.7 mW m-2/Tg(N) yr-1 is in contrast with the 'fixed addition' method. For determining regional NOx GWPs, it is argued that the 'proportional' approach gives more representative results. However, a constraint of both approaches is that the regional GWP determined is dependent on the relative global emission pattern, so if that changes in the future, the regional NOx GWP will change.

Beyond Impervious: Urban Land-Cover Pattern Variation and Implications for Watershed Management

NASA Astrophysics Data System (ADS)

Beck, Scott M.; McHale, Melissa R.; Hess, George R.

2016-07-01

Impervious surfaces degrade urban water quality, but their over-coverage has not explained the persistent water quality variation observed among catchments with similar rates of imperviousness. Land-cover patterns likely explain much of this variation, although little is known about how they vary among watersheds. Our goal was to analyze a series of urban catchments within a range of impervious cover to evaluate how land-cover varies among them. We then highlight examples from the literature to explore the potential effects of land-cover pattern variability for urban watershed management. High-resolution (1 m2) land-cover data were used to quantify 23 land-cover pattern and stormwater infrastructure metrics within 32 catchments across the Triangle Region of North Carolina. These metrics were used to analyze variability in land-cover patterns among the study catchments. We used hierarchical clustering to organize the catchments into four groups, each with a distinct landscape pattern. Among these groups, the connectivity of combined land-cover patches accounted for 40 %, and the size and shape of lawns and buildings accounted for 20 %, of the overall variation in land-cover patterns among catchments. Storm water infrastructure metrics accounted for 8 % of the remaining variation. Our analysis demonstrates that land-cover patterns do vary among urban catchments, and that trees and grass (lawns) are divergent cover types in urban systems. The complex interactions among land-covers have several direct implications for the ongoing management of urban watersheds.

Cigarette Smoking Predicts Differential Benefit from Naltrexone for Alcohol Dependence

PubMed Central

Fucito, Lisa M.; Park, Aesoon; Gulliver, Suzy Bird; Mattson, Margaret E.; Gueorguieva, Ralitza V.; O’Malley, Stephanie S.

2012-01-01

Background Identifying factors that modify responsiveness to pharmacotherapies for alcohol dependence is important for treatment planning. Cigarette smoking predicts more severe alcohol dependence and poorer treatment response in general. Nevertheless, there is limited research on cigarette smoking as a potential predictor of differential response to pharmacological treatment of alcoholism. Methods We examined the association between cigarette smoking and drinking outcomes in the COMBINE study, a randomized, double-blind placebo-controlled 16-week trial comparing combinations of medications (i.e., acamprosate and naltrexone) and behavioral interventions (i.e., medical management (MM), combined behavioral therapy (CBI)) in 1383 alcohol dependent individuals. Results Smokers (i.e., more than half the sample) significantly differed from nonsmokers on several demographic and drinking-related variables at baseline and generally had poorer treatment outcomes than nonsmokers. However, smokers who received naltrexone had better drinking outcomes than smokers who received placebo, whereas alcohol use among nonsmokers did not vary by naltrexone assignment. This pattern of findings occurred independent of whether patients received CBI or MM and remained after controlling for alcoholism typology and baseline demographic differences. Approximately 9% of smokers quit smoking and an additional 10% reduced their cigarette intake during treatment. Reductions in smoking did not vary by treatment assignment. Conclusions These results suggest that naltrexone may be particularly beneficial for improving alcohol use outcomes in alcohol dependent smokers. Trial Registration The COMBINE Study, NCT000626, http://www.cscc.unc.edu/combine/. PMID:22541040

Control of Turing patterns and their usage as sensors, memory arrays, and logic gates

NASA Astrophysics Data System (ADS)

Muzika, František; Schreiber, Igor

2013-10-01

We study a model system of three diffusively coupled reaction cells arranged in a linear array that display Turing patterns with special focus on the case of equal coupling strength for all components. As a suitable model reaction we consider a two-variable core model of glycolysis. Using numerical continuation and bifurcation techniques we analyze the dependence of the system's steady states on varying rate coefficient of the recycling step while the coupling coefficients of the inhibitor and activator are fixed and set at the ratios 100:1, 1:1, and 4:5. We show that stable Turing patterns occur at all three ratios but, as expected, spontaneous transition from the spatially uniform steady state to the spatially nonuniform Turing patterns occurs only in the first case. The other two cases possess multiple Turing patterns, which are stabilized by secondary bifurcations and coexist with stable uniform periodic oscillations. For the 1:1 ratio we examine modular spatiotemporal perturbations, which allow for controllable switching between the uniform oscillations and various Turing patterns. Such modular perturbations are then used to construct chemical computing devices utilizing the multiple Turing patterns. By classifying various responses we propose: (a) a single-input resettable sensor capable of reading certain value of concentration, (b) two-input and three-input memory arrays capable of storing logic information, (c) three-input, three-output logic gates performing combinations of logical functions OR, XOR, AND, and NAND.

Dedicated high dose rate 192Ir brachytherapy radiation fields for in vitro cell exposures at variable source-target cell distances: killing of mammalian cells depends on temporal dose rate fluctuation

NASA Astrophysics Data System (ADS)

Veigel, Cornelia; Hartmann, Günther H.; Fritz, Peter; Debus, Jürgen; Weber, Klaus-Josef

2017-02-01

Afterloading brachytherapy is conducted by the stepwise movement of a radioactive source through surgically implanted applicator tubes where at predefined dwell positions calculated dwell times optimize spatial dose delivery with respect to a planned dose level. The temporal exposure pattern exhibits drastic fluctuations in dose rate at a given coordinate and within a single treatment session because of the discontinuous and repeated source movement into the target volume. This could potentially affect biological response. Therefore, mammalian cells were exposed as monolayers to a high dose rate 192Ir source by utilizing a dedicated irradiation device where the distance between a planar array of radioactive source positions and the plane of the cell monolayer could be varied from 2.5 mm to 40 mm, thus varying dose rate pattern for any chosen total dose. The Gammamed IIi afterloading system equipped with a nominal 370 GBq (10 Ci) 192-Ir source was used to irradiate V79 Chinese hamster lung fibroblasts from both confluent and from exponential growth phase with dose up to 12 Gy (at room temperature, total exposure not exceeding 1 h). For comparison, V79 cells were also exposed to 6 MV x-rays from a clinical linear accelerator (dose rate of 2.5 Gy min-1). As biological endpoint, cell survival was determined by standard colony forming assay. Dose measurements were conducted with a diamond detector (sensitive area 7.3 mm2), calibrated by means of 60Co radiation. Additionally, dose delivery was simulated by Monte Carlo calculations using the EGSnrc code system. The calculated secondary electron fluence spectra at the cell location did not indicate a significant change of radiation quality (i.e. higher linear energy transfer) at the lower distances. Clonogenic cell survival curves obtained after brachytherapy exhibited an altered biological response compared to x-rays which was characterized by a significant reduction of the survival curve shoulder when dose rate fluctuations were high. Therefore, also for the time scale of the present investigation, cellular effects of radiation are not invariant to the temporal pattern in dose rate. We propose that with high dose rate variation the cells activate less efficiently their DNA damage response than after continuous irradiation.

Major determinants of the biogeographic pattern of the shallow-sea fauna

NASA Technical Reports Server (NTRS)

Valentine, J. W.; Jablonski, D.

1982-01-01

The benthic shallow-sea is defined as the region of sea floor lying between the supralittoral zone at the shoreline and the impingement of the thermocline separating a warm shallow and variable portion of the water column from rather homogeneous and constant cooler waters beneath. Three types of shallow-sea provinces can be recognized: (1) one-dimensional, linear shelves; (2) two-dimensional shelves; and (3) scattered islands in two-dimensional arrays. Dispersal powers of marine invertebrates vary with developmental mode, and patterns of dispersal, endemism and speciation vary among the different provincial types. Invertebrate developmental modes vary systematically with geography, and presumably are adaptive to environmental conditions. Clades with only a single mode of development tend to be restricted to regions appropriate to that mode, significantly affecting their biogeographic patterns. The consequences of geographic and other environmental changes are reviewed.

Auditory stream segregation in monkey auditory cortex: effects of frequency separation, presentation rate, and tone duration

NASA Astrophysics Data System (ADS)

Fishman, Yonatan I.; Arezzo, Joseph C.; Steinschneider, Mitchell

2004-09-01

Auditory stream segregation refers to the organization of sequential sounds into ``perceptual streams'' reflecting individual environmental sound sources. In the present study, sequences of alternating high and low tones, ``...ABAB...,'' similar to those used in psychoacoustic experiments on stream segregation, were presented to awake monkeys while neural activity was recorded in primary auditory cortex (A1). Tone frequency separation (ΔF), tone presentation rate (PR), and tone duration (TD) were systematically varied to examine whether neural responses correlate with effects of these variables on perceptual stream segregation. ``A'' tones were fixed at the best frequency of the recording site, while ``B'' tones were displaced in frequency from ``A'' tones by an amount=ΔF. As PR increased, ``B'' tone responses decreased in amplitude to a greater extent than ``A'' tone responses, yielding neural response patterns dominated by ``A'' tone responses occurring at half the alternation rate. Increasing TD facilitated the differential attenuation of ``B'' tone responses. These findings parallel psychoacoustic data and suggest a physiological model of stream segregation whereby increasing ΔF, PR, or TD enhances spatial differentiation of ``A'' tone and ``B'' tone responses along the tonotopic map in A1.

Projections of Southern Hemisphere atmospheric circulation interannual variability

NASA Astrophysics Data System (ADS)

Grainger, Simon; Frederiksen, Carsten S.; Zheng, Xiaogu

2017-02-01

An analysis is made of the coherent patterns, or modes, of interannual variability of Southern Hemisphere 500 hPa geopotential height field under current and projected climate change scenarios. Using three separate multi-model ensembles (MMEs) of coupled model intercomparison project phase 5 (CMIP5) models, the interannual variability of the seasonal mean is separated into components related to (1) intraseasonal processes; (2) slowly-varying internal dynamics; and (3) the slowly-varying response to external changes in radiative forcing. In the CMIP5 RCP8.5 and RCP4.5 experiments, there is very little change in the twenty-first century in the intraseasonal component modes, related to the Southern annular mode (SAM) and mid-latitude wave processes. The leading three slowly-varying internal component modes are related to SAM, the El Niño-Southern oscillation (ENSO), and the South Pacific wave (SPW). Structural changes in the slow-internal SAM and ENSO modes do not exceed a qualitative estimate of the spatial sampling error, but there is a consistent increase in the ENSO-related variance. Changes in the SPW mode exceed the sampling error threshold, but cannot be further attributed. Changes in the dominant slowly-varying external mode are related to projected changes in radiative forcing. They reflect thermal expansion of the tropical troposphere and associated changes in the Hadley Cell circulation. Changes in the externally-forced associated variance in the RCP8.5 experiment are an order of magnitude greater than for the internal components, indicating that the SH seasonal mean circulation will be even more dominated by a SAM-like annular structure. Across the three MMEs, there is convergence in the projected response in the slow-external component.

Comparative nucleotide diversity across North American and European populus species.

PubMed

Ismail, Mohamed; Soolanayakanahally, Raju Y; Ingvarsson, Pär K; Guy, Robert D; Jansson, Stefan; Silim, Salim N; El-Kassaby, Yousry A

2012-06-01

Nucleotide polymorphisms in two North American balsam poplars (Populus trichocarpa Torr. & Gray and P. balsamifera L.; section Tacamahaca), and one Eurasian aspen (P. tremula L.; section Populus) were compared using nine loci involved in defense, stress response, photoperiodism, freezing tolerance, and housekeeping. Nucleotide diversity varied among species and was highest for P. tremula (θ(w) = 0.005, π(T) = 0.007) as compared to P. balsamifera (θ(w) = 0.004, π(T) = 0.005) or P. trichocarpa (θ(w) = 0.002, π(T) = 0.003). Across species, the defense and the stress response loci accounted for the majority of the observed level of nucleotide diversity. In general, the studied loci did not deviate from neutral expectation either at the individual locus (non-significant normalized Fay and Wu's H) or at the multi-locus level (non-significant HKA test). Using molecular clock analysis, section Tacamahaca probably shared a common ancestor with section Populus approximately 4.5 million year ago. Divergence between the two closely related balsam poplars was about 0.8 million years ago, a pattern consistent with an isolation-with-migration (IM) model. As expected, P. tremula showed a five-fold higher substitution rate (2 × 10(-8) substitution/site/year) compared to the North American species (0.4 × 10(-8) substitution/site/year), probably reflecting its complex demographic history. Linkage disequilibrium (LD) varied among species with a more rapid decay in the North American species (<400 bp) in comparison to P. tremula (≫400 bp). The similarities in nucleotide diversity pattern and LD decay of the two balsam poplar species likely reflects the recent time of their divergence.

Isolating age-group differences in working memory load-related neural activity: assessing the contribution of working memory capacity using a partial-trial fMRI method.

PubMed

Bennett, Ilana J; Rivera, Hannah G; Rypma, Bart

2013-05-15

Previous studies examining age-group differences in working memory load-related neural activity have yielded mixed results. When present, age-group differences in working memory capacity are frequently proposed to underlie these neural effects. However, direct relationships between working memory capacity and working memory load-related activity have only been observed in younger adults. These relationships remain untested in healthy aging. Therefore, the present study examined patterns of working memory load-related activity in 22 younger and 20 older adults and assessed the contribution of working memory capacity to these load-related effects. Participants performed a partial-trial delayed response item recognition task during functional magnetic resonance imaging. In this task, participants encoded either 2 or 6 letters, maintained them during a delay, and then indicated whether a probe was present in the memory set. Behavioral results revealed faster and more accurate responses to load 2 versus 6, with age-group differences in this load condition effect for the accuracy measure. Neuroimaging results revealed one region (medial superior frontal gyrus) that showed age-group differences in load-related activity during the retrieval period, with less (greater) neural activity for the low versus high load condition in younger (older) adults. Furthermore, for older adults, load-related activity did not vary as a function of working memory capacity. Thus, working memory-related activity varies with healthy aging, but these patterns are not due solely to working memory capacity. Neurocognitive aging theories that feature capacity will need to account for these results. Copyright © 2013 Elsevier Inc. All rights reserved.

Correlated variation of floral and leaf traits along a moisture availability gradient.

PubMed

Lambrecht, Susan C; Dawson, Todd E

2007-04-01

Variation in flower size is an important aspect of a plant's life history, yet few studies have shown how flower size varies with environmental conditions and to what extent foliar responses to the environment are correlated with flower size. The objectives of this study were to (1) develop a theoretical framework for linking flower size and leaf size to their costs and benefits, as assessed using foliar stable carbon isotope ratio (delta(13)C) under varying degrees of water limitation, and then (2) examine how variation in flower size within and among species growing along a naturally occurring moisture availability gradient correlates with variation in delta(13)C and leaf size. Five plant species were examined at three sites in Oregon. Intra- and inter-specific patterns of flower size in relation to moisture availability were the same: the ratios of the area of flower display to total leaf area and of individual flower area to leaf area were greater at sites with more soil moisture compared to those sites with less soil moisture. The increase in flower area per unit increase in leaf area was greater at sites with more soil moisture than at sites where water deficit can occur. Values of delta(13)C, an index of water-use efficiency, were greater for plants with larger floral size. The patterns we observed generalize across species, irrespective of overall plant morphology or pollination system. These correlations between flower size, moisture availability, and delta(13)C suggest that water loss from flowers can influence leaf responses to the environment, which in turn may indirectly mediate an effect on flower size.

Cortical activation patterns correlate with speech understanding after cochlear implantation

PubMed Central

Olds, Cristen; Pollonini, Luca; Abaya, Homer; Larky, Jannine; Loy, Megan; Bortfeld, Heather; Beauchamp, Michael S.; Oghalai, John S.

2015-01-01

Objectives Cochlear implants are a standard therapy for deafness, yet the ability of implanted patients to understand speech varies widely. To better understand this variability in outcomes, we used functional near-infrared spectroscopy (fNIRS) to image activity within regions of the auditory cortex and compare the results to behavioral measures of speech perception. Design We studied 32 deaf adults hearing through cochlear implants and 35 normal-hearing controls. We used fNIRS to measure responses within the lateral temporal lobe and the superior temporal gyrus to speech stimuli of varying intelligibility. The speech stimuli included normal speech, channelized speech (vocoded into 20 frequency bands), and scrambled speech (the 20 frequency bands were shuffled in random order). We also used environmental sounds as a control stimulus. Behavioral measures consisted of the Speech Reception Threshold, CNC words, and AzBio Sentence tests measured in quiet. Results Both control and implanted participants with good speech perception exhibited greater cortical activations to natural speech than to unintelligible speech. In contrast, implanted participants with poor speech perception had large, indistinguishable cortical activations to all stimuli. The ratio of cortical activation to normal speech to that of scrambled speech directly correlated with the CNC Words and AzBio Sentences scores. This pattern of cortical activation was not correlated with auditory threshold, age, side of implantation, or time after implantation. Turning off the implant reduced cortical activations in all implanted participants. Conclusions Together, these data indicate that the responses we measured within the lateral temporal lobe and the superior temporal gyrus correlate with behavioral measures of speech perception, demonstrating a neural basis for the variability in speech understanding outcomes after cochlear implantation. PMID:26709749

Measurement of instantaneous rotational speed using double-sine-varying-density fringe pattern

NASA Astrophysics Data System (ADS)

Zhong, Jianfeng; Zhong, Shuncong; Zhang, Qiukun; Peng, Zhike

2018-03-01

Fast and accurate rotational speed measurement is required both for condition monitoring and faults diagnose of rotating machineries. A vision- and fringe pattern-based rotational speed measurement system was proposed to measure the instantaneous rotational speed (IRS) with high accuracy and reliability. A special double-sine-varying-density fringe pattern (DSVD-FP) was designed and pasted around the shaft surface completely and worked as primary angular sensor. The rotational angle could be correctly obtained from the left and right fringe period densities (FPDs) of the DSVD-FP image sequence recorded by a high-speed camera. The instantaneous angular speed (IAS) between two adjacent frames could be calculated from the real-time rotational angle curves, thus, the IRS also could be obtained accurately and efficiently. Both the measurement principle and system design of the novel method have been presented. The influence factors on the sensing characteristics and measurement accuracy of the novel system, including the spectral centrobaric correction method (SCCM) on the FPD calculation, the noise sources introduce by the image sensor, the exposure time and the vibration of the shaft, were investigated through simulations and experiments. The sampling rate of the high speed camera could be up to 5000 Hz, thus, the measurement becomes very fast and the change in rotational speed was sensed within 0.2 ms. The experimental results for different IRS measurements and characterization of the response property of a servo motor demonstrated the high accuracy and fast measurement of the proposed technique, making it attractive for condition monitoring and faults diagnosis of rotating machineries.

Viewing time measures of sexual orientation in Samoan cisgender men who engage in sexual interactions with fa'afafine.

PubMed

Petterson, Lanna J; Dixson, Barnaby J; Little, Anthony C; Vasey, Paul L

2015-01-01

Androphilia refers to attraction to adult males, whereas gynephilia refers to attraction to adult females. The current study employed self-report and viewing time (response time latency) measures of sexual attraction to determine the sexual orientation of Samoan cisgender men (i.e., males whose gender presentation and identity is concordant with their biological sex) who engage in sexual interactions with transgender male androphiles (known locally as fa'afafine) compared to: (1) Samoan cisgender men who only engage in sexual interactions with women, and (2) fa'afafine. As expected, both measures indicated that cisgender men who only engaged in sexual interactions with women exhibited a gynephilic pattern of sexual attraction, whereas fa'afafine exhibited an androphilic one. In contrast, both measures indicated that cisgender men who engaged in sexual interactions with fa'afafine demonstrated a bisexual pattern of sexual attraction. Most of the cisgender men who exhibited bisexual viewing times did not engage in sexual activity with both men and women indicating that the manner in which bisexual patterns of sexual attraction manifest behaviorally vary from one culture to the next.

Delay time correction of the gas analyzer in the calculation of anatomical dead space of the lung.

PubMed

Okubo, T; Shibata, H; Takishima, T

1983-07-01

By means of a mathematical model, we have studied a way to correct the delay time of the gas analyzer in order to calculate the anatomical dead space using Fowler's graphical method. The mathematical model was constructed of ten tubes of equal diameter but unequal length, so that the amount of dead space varied from tube to tube; the tubes were emptied sequentially. The gas analyzer responds with a time lag from the input of the gas signal to the beginning of the response, followed by an exponential response output. The single breath expired volume-concentration relationship was examined with three types of expired flow patterns of which were constant, exponential and sinusoidal. The results indicate that the time correction by the lag time plus time constant of the exponential response of the gas analyzer gives an accurate estimation of anatomical dead space. Time correction less inclusive than this, e.g. lag time only or lag time plus 50% response time, gives an overestimation, and a correction larger than this results in underestimation. The magnitude of error is dependent on the flow pattern and flow rate. The time correction in this study is only for the calculation of dead space, as the corrected volume-concentration curves does not coincide with the true curve. Such correction of the output of the gas analyzer is extremely important when one needs to compare the dead spaces of different gas species at a rather faster flow rate.

Spread the word: MMN brain response reveals whole-form access of discontinuous particle verbs.

PubMed

Hanna, Jeff; Cappelle, Bert; Pulvermüller, Friedemann

2017-12-01

The status of particle verbs such as rise (…) up as either lexically stored or combinatorially assembled is an issue which so far has not been settled decisively. In this study, we use the mismatch negativity (MMN) brain response to observe neurophysiological responses to discontinuous particle verbs. The MMN can be used to distinguish between whole-form storage and combinatorial processes, as it is enhanced to stored words compared to unknown pseudowords, whereas combinatorially legal strings elicit a reduced MMN relative to ungrammatical ones. Earlier work had found larger MMNs to congruent than to incongruent verb-particle combinations when particle and verb appeared as adjacent elements, thus suggesting whole-form storage at least in this case. However, it is still possible that particle verbs discontinuously spread out across a sentence would elicit the combinatorial, grammar-violation response pattern instead. Here, we tested the brain signatures of discontinuous verb-particle combinations, orthogonally varying congruence and semantic transparency. The results show for the first time brain indices of whole-form storage for discontinuous constituents, thus arguing in favour of access to whole-form-stored lexical elements in the processing of particle verbs, irrespective of their semantic opacity. Results are discussed in the context of linguistic debates about the status of particle verbs as words, lexical elements or syntactically generated combinations. The explanation of the pattern of results within a neurobiological language model is highlighted. Copyright © 2017 Elsevier Inc. All rights reserved.

Stochastic analysis of epidemics on adaptive time varying networks

NASA Astrophysics Data System (ADS)

Kotnis, Bhushan; Kuri, Joy

2013-06-01

Many studies investigating the effect of human social connectivity structures (networks) and human behavioral adaptations on the spread of infectious diseases have assumed either a static connectivity structure or a network which adapts itself in response to the epidemic (adaptive networks). However, human social connections are inherently dynamic or time varying. Furthermore, the spread of many infectious diseases occur on a time scale comparable to the time scale of the evolving network structure. Here we aim to quantify the effect of human behavioral adaptations on the spread of asymptomatic infectious diseases on time varying networks. We perform a full stochastic analysis using a continuous time Markov chain approach for calculating the outbreak probability, mean epidemic duration, epidemic reemergence probability, etc. Additionally, we use mean-field theory for calculating epidemic thresholds. Theoretical predictions are verified using extensive simulations. Our studies have uncovered the existence of an “adaptive threshold,” i.e., when the ratio of susceptibility (or infectivity) rate to recovery rate is below the threshold value, adaptive behavior can prevent the epidemic. However, if it is above the threshold, no amount of behavioral adaptations can prevent the epidemic. Our analyses suggest that the interaction patterns of the infected population play a major role in sustaining the epidemic. Our results have implications on epidemic containment policies, as awareness campaigns and human behavioral responses can be effective only if the interaction levels of the infected populace are kept in check.

Two Parallel Olfactory Pathways for Processing General Odors in a Cockroach

PubMed Central

Watanabe, Hidehiro; Nishino, Hiroshi; Mizunami, Makoto; Yokohari, Fumio

2017-01-01

In animals, sensory processing via parallel pathways, including the olfactory system, is a common design. However, the mechanisms that parallel pathways use to encode highly complex and dynamic odor signals remain unclear. In the current study, we examined the anatomical and physiological features of parallel olfactory pathways in an evolutionally basal insect, the cockroach Periplaneta americana. In this insect, the entire system for processing general odors, from olfactory sensory neurons to higher brain centers, is anatomically segregated into two parallel pathways. Two separate populations of secondary olfactory neurons, type1 and type2 projection neurons (PNs), with dendrites in distinct glomerular groups relay olfactory signals to segregated areas of higher brain centers. We conducted intracellular recordings, revealing olfactory properties and temporal patterns of both types of PNs. Generally, type1 PNs exhibit higher odor-specificities to nine tested odorants than type2 PNs. Cluster analyses revealed that odor-evoked responses were temporally complex and varied in type1 PNs, while type2 PNs exhibited phasic on-responses with either early or late latencies to an effective odor. The late responses are 30–40 ms later than the early responses. Simultaneous intracellular recordings from two different PNs revealed that a given odor activated both types of PNs with different temporal patterns, and latencies of early and late responses in type2 PNs might be precisely controlled. Our results suggest that the cockroach is equipped with two anatomically and physiologically segregated parallel olfactory pathways, which might employ different neural strategies to encode odor information. PMID:28529476

Differential responses in dorsal visual cortex to motion and disparity depth cues

PubMed Central

Arnoldussen, David M.; Goossens, Jeroen; van den Berg, Albert V.

2013-01-01

We investigated how interactions between monocular motion parallax and binocular cues to depth vary in human motion areas for wide-field visual motion stimuli (110 × 100°). We used fMRI with an extensive 2 × 3 × 2 factorial blocked design in which we combined two types of self-motion (translational motion and translational + rotational motion), with three categories of motion inflicted by the degree of noise (self-motion, distorted self-motion, and multiple object-motion), and two different view modes of the flow patterns (stereo and synoptic viewing). Interactions between disparity and motion category revealed distinct contributions to self- and object-motion processing in 3D. For cortical areas V6 and CSv, but not the anterior part of MT+ with bilateral visual responsiveness (MT+/b), we found a disparity-dependent effect of rotational flow and noise: When self-motion perception was degraded by adding rotational flow and moderate levels of noise, the BOLD responses were reduced compared with translational self-motion alone, but this reduction was cancelled by adding stereo information which also rescued the subject's self-motion percept. At high noise levels, when the self-motion percept gave way to a swarm of moving objects, the BOLD signal strongly increased compared to self-motion in areas MT+/b and V6, but only for stereo in the latter. BOLD response did not increase for either view mode in CSv. These different response patterns indicate different contributions of areas V6, MT+/b, and CSv to the processing of self-motion perception and the processing of multiple independent motions. PMID:24339808

Effects of elevated CO₂, warming and precipitation change on plant growth, photosynthesis and peroxidation in dominant species from North China grassland.

PubMed

Xu, Zhenzhu; Shimizu, Hideyuki; Ito, Shoko; Yagasaki, Yasumi; Zou, Chunjing; Zhou, Guangsheng; Zheng, Yuanrun

2014-02-01

Warming, watering and elevated atmospheric CO₂-concentration effects have been extensively studied separately; however, their combined impact on plants is not well understood. In the current research, we examined plant growth and physiological responses of three dominant species from the Eurasian Steppe with different functional traits to a combination of elevated CO₂, high temperature, and four simulated precipitation patterns. Elevated CO₂ stimulated plant growth by 10.8-41.7 % for a C₃ leguminous shrub, Caragana microphylla, and by 33.2-52.3 % for a C₃ grass, Stipa grandis, across all temperature and watering treatments. Elevated CO₂, however, did not affect plant biomass of a C₄ grass, Cleistogenes squarrosa, under normal or increased precipitation, whereas a 20.0-69.7 % stimulation of growth occurred with elevated CO₂ under drought conditions. Plant growth was enhanced in the C₃ shrub and the C₄ grass by warming under normal precipitation, but declined drastically with severe drought. The effects of elevated CO₂ on leaf traits, biomass allocation and photosynthetic potential were remarkably species-dependent. Suppression of photosynthetic activity, and enhancement of cell peroxidation by a combination of warming and severe drought, were partly alleviated by elevated CO₂. The relationships between plant functional traits and physiological activities and their responses to climate change were discussed. The present results suggested that the response to CO₂ enrichment may strongly depend on the response of specific species under varying patterns of precipitation, with or without warming, highlighting that individual species and multifactor dependencies must be considered in a projection of terrestrial ecosystem response to climatic change.

Long-term variation in the winter resident bird community of Guanica Forest, Puerto Rico: lessons for measuring and monitoring species richness.

Treesearch

John Faaborg; Katie M. Dugger; Wayne J. Arendt

2007-01-01

Because the winter season is potentially limiting for migratory birds, understanding their nonbreeding distributional patterns is essential. At a given site, patterns of species occurrence and abundance may vary over time and, within a species, wintering strategies may vary with regard to the degree that individuals are site-faithful both within and between winters. We...

A Theoretical Approach to Analyze the Parametric Influence on Spatial Patterns of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) Populations.

PubMed

Garcia, A G; Godoy, W A C

2017-06-01

Studies of the influence of biological parameters on the spatial distribution of lepidopteran insects can provide useful information for managing agricultural pests, since the larvae of many species cause serious impacts on crops. Computational models to simulate the spatial dynamics of insect populations are increasingly used, because of their efficiency in representing insect movement. In this study, we used a cellular automata model to explore different patterns of population distribution of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), when the values of two biological parameters that are able to influence the spatial pattern (larval viability and adult longevity) are varied. We mapped the spatial patterns observed as the parameters varied. Additionally, by using population data for S. frugiperda obtained in different hosts under laboratory conditions, we were able to describe the expected spatial patterns occurring in corn, cotton, millet, and soybean crops based on the parameters varied. The results are discussed from the perspective of insect ecology and pest management. We concluded that computational approaches can be important tools to study the relationship between the biological parameters and spatial distributions of lepidopteran insect pests.

Dietary patterns and socioeconomic position.

PubMed

Mullie, P; Clarys, P; Hulens, M; Vansant, G

2010-03-01

To test a socioeconomic hypothesis on three dietary patterns and to describe the relation between three commonly used methods to determine dietary patterns, namely Healthy Eating Index, Mediterranean Diet Score and principal component analysis. Cross-sectional design in 1852 military men. Using mailed questionnaires, the food consumption frequency was recorded. The correlation coefficients between the three dietary patterns varied between 0.43 and 0.62. The highest correlation was found between Healthy Eating Index and Healthy Dietary Pattern (principal components analysis). Cohen's kappa coefficient of agreement varied between 0.10 and 0.20. After age-adjustment, education and income remained associated with the most healthy dietary pattern. Even when both socioeconomic indicators were used together in one model, higher income and education were associated with higher scores for Healthy Eating Index, Mediterranean Diet Score and Healthy Dietary Pattern. The least healthy quintiles of dietary pattern as measured by the three methods were associated with a clustering of unhealthy behaviors, that is, smoking, low physical activity, highest intake of total fat and saturated fatty acids, and low intakes of fruits and vegetables. The three dietary patterns used indicated that the most healthy patterns were associated with a higher socioeconomic position, while lower patterns were associated with several unhealthy behaviors.

Predator diversity reduces habitat colonization by mosquitoes and midges.

PubMed

Staats, Ethan G; Agosta, Salvatore J; Vonesh, James R

2016-12-01

Changes in predator diversity via extinction and invasion are increasingly widespread and can have important ecological and socio-economic consequences. Anticipating and managing these consequences requires understanding how predators shape ecological communities. Previous predator biodiversity research has focused on post-colonization processes. However, predators can also shape communities by altering patterns of prey habitat selection during colonization. The sensitivity of this non-consumptive top down mechanism to changes in predator diversity is largely unexamined. To address this gap, we examined patterns of dipteran oviposition habitat selection in experimental aquatic habitats in response to varied predator species richness while holding predator abundance constant. Caged predators were used in order to disentangle behavioural oviposition responses to predator cues from potential post-oviposition consumption of eggs and larvae. We hypothesized that because increases in predator richness often result in greater prey mortality than would be predicted from independent effects of predators, prey should avoid predator-rich habitats during colonization. Consistent with this hypothesis, predator-rich habitats received 48% fewer dipteran eggs than predicted, including 60% fewer mosquito eggs and 38% fewer midge eggs. Our findings highlight the potentially important links between predator biodiversity, prey habitat selection and the ecosystem service of pest regulation. © 2016 The Author(s).

Protein-DNA binding dynamics predict transcriptional response to nutrients in archaea.

PubMed

Todor, Horia; Sharma, Kriti; Pittman, Adrianne M C; Schmid, Amy K

2013-10-01

Organisms across all three domains of life use gene regulatory networks (GRNs) to integrate varied stimuli into coherent transcriptional responses to environmental pressures. However, inferring GRN topology and regulatory causality remains a central challenge in systems biology. Previous work characterized TrmB as a global metabolic transcription factor in archaeal extremophiles. However, it remains unclear how TrmB dynamically regulates its ∼100 metabolic enzyme-coding gene targets. Using a dynamic perturbation approach, we elucidate the topology of the TrmB metabolic GRN in the model archaeon Halobacterium salinarum. Clustering of dynamic gene expression patterns reveals that TrmB functions alone to regulate central metabolic enzyme-coding genes but cooperates with various regulators to control peripheral metabolic pathways. Using a dynamical model, we predict gene expression patterns for some TrmB-dependent promoters and infer secondary regulators for others. Our data suggest feed-forward gene regulatory topology for cobalamin biosynthesis. In contrast, purine biosynthesis appears to require TrmB-independent regulators. We conclude that TrmB is an important component for mediating metabolic modularity, integrating nutrient status and regulating gene expression dynamics alone and in concert with secondary regulators.

Mental fatigue detection based on the functional near infrared spectroscopy

NASA Astrophysics Data System (ADS)

Zhang, Zhen; Xu, Fenggang; Yang, Hanjun; Jiang, Jin; Cao, Yong; Jiao, Xuejun

2017-02-01

Mental fatigue can be induced by long time mental work, mental fatigue caused worse performance and accidents. As a non-invasive technique, functional near-infrared spectroscopy (fNIRS) can measure blood oxygen activity in the cerebral cortex which reflect the cognitive function of brain indirectly. Aiming at investigating whether fNIRS can measure the mental fatigue and study the spatial pattern of hemodynamic response for mental fatigue, we used three sessions of verbal 2-back working memory task for a total of 120 minutes to induce mental fatigue, 15 healthy subjects were recruited and 30 channels including prefrontal cortex (PFC) and motor cortex (MC) were measured by fNIRS. The mean oxyhemoglobin feature for 20s was extracted as well as subjective fatigue level and performance. The results showed significant increase of subjected fatigue level as well as significant decrease performance from session one to three task. With the increased level of fatigue, oxyhemoglobin in PFC increase significantly and the spatial pattern of hemodynamic response in the all 30 channels varied with task duration as well. These findings indicated the potential of fNIRS measured hemodynamic as a mental fatigue indicator.

Scale effects on spatially varying relationships between urban landscape patterns and water quality.

PubMed

Sun, Yanwei; Guo, Qinghai; Liu, Jian; Wang, Run

2014-08-01

Scientific interpretation of the relationships between urban landscape patterns and water quality is important for sustainable urban planning and watershed environmental protection. This study applied the ordinary least squares regression model and the geographically weighted regression model to examine the spatially varying relationships between 12 explanatory variables (including three topographical factors, four land use parameters, and five landscape metrics) and 15 water quality indicators in watersheds of Yundang Lake, Maluan Bay, and Xinglin Bay with varying levels of urbanization in Xiamen City, China. A local and global investigation was carried out at the watershed-level, with 50 and 200 m riparian buffer scales. This study found that topographical features and landscape metrics are the dominant factors of water quality, while land uses are too weak to be considered as a strong influential factor on water quality. Such statistical results may be related with the characteristics of land use compositions in our study area. Water quality variations in the 50 m buffer were dominated by topographical variables. The impact of landscape metrics on water quality gradually strengthen with expanding buffer zones. The strongest relationships are obtained in entire watersheds, rather than in 50 and 200 m buffer zones. Spatially varying relationships and effective buffer zones were verified in this study. Spatially varying relationships between explanatory variables and water quality parameters are more diversified and complex in less urbanized areas than in highly urbanized areas. This study hypothesizes that all these varying relationships may be attributed to the heterogeneity of landscape patterns in different urban regions. Adjustment of landscape patterns in an entire watershed should be the key measure to successfully improving urban lake water quality.

Can local adaptation explain varying patterns of herbivory tolerance in a recently introduced woody plant in North America?

PubMed

Long, Randall W; Bush, Susan E; Grady, Kevin C; Smith, David S; Potts, Daniel L; D'Antonio, Carla M; Dudley, Tom L; Fehlberg, Shannon D; Gaskin, John F; Glenn, Edward P; Hultine, Kevin R

2017-01-01

Patterns of woody-plant mortality have been linked to global-scale environmental changes, such as extreme drought, heat stress, more frequent and intense fires, and episodic outbreaks of insects and pathogens. Although many studies have focussed on survival and mortality in response to specific physiological stresses, little attention has been paid to the role of genetic heritability of traits and local adaptation in influencing patterns of plant mortality, especially in non-native species. Tamarix spp. is a dominant, non-native riparian tree in western North America that is experiencing dieback in some areas of its range due to episodic herbivory by the recently introduced northern tamarisk leaf beetle ( Diorhabda carinulata ). We propose that genotype × environment interactions largely underpin current and future patterns of Tamarix mortality. We anticipate that (i) despite its recent introduction, and the potential for significant gene flow, Tamarix in western North America is generally adapted to local environmental conditions across its current range in part due to hybridization of two species; (ii) local adaptation to specific climate, soil and resource availability will yield predictable responses to episodic herbivory; and (iii) the ability to cope with a combination of episodic herbivory and increased aridity associated with climate change will be largely based on functional tradeoffs in resource allocation. This review focusses on the potential heritability of plant carbon allocation patterns in Tamarix , focussing on the relative contribution of acquired carbon to non-structural carbohydrate (NSC) pools versus other sinks as the basis for surviving episodic disturbance. Where high aridity and/or poor edaphic position lead to chronic stress, NSC pools may fall below a minimum threshold because of an imbalance between the supply of carbon and its demand by various sinks. Identifying patterns of local adaptation of traits related to resource allocation will improve forecasting of Tamarix population susceptibility to episodic herbivory.

Can local adaptation explain varying patterns of herbivory tolerance in a recently introduced woody plant in North America?

PubMed Central

Bush, Susan E.; Grady, Kevin C.; Smith, David S.; Potts, Daniel L.; D'Antonio, Carla M.; Dudley, Tom L.; Fehlberg, Shannon D.; Gaskin, John F.; Glenn, Edward P.; Hultine, Kevin R.

2017-01-01

Abstract Patterns of woody-plant mortality have been linked to global-scale environmental changes, such as extreme drought, heat stress, more frequent and intense fires, and episodic outbreaks of insects and pathogens. Although many studies have focussed on survival and mortality in response to specific physiological stresses, little attention has been paid to the role of genetic heritability of traits and local adaptation in influencing patterns of plant mortality, especially in non-native species. Tamarix spp. is a dominant, non-native riparian tree in western North America that is experiencing dieback in some areas of its range due to episodic herbivory by the recently introduced northern tamarisk leaf beetle (Diorhabda carinulata). We propose that genotype × environment interactions largely underpin current and future patterns of Tamarix mortality. We anticipate that (i) despite its recent introduction, and the potential for significant gene flow, Tamarix in western North America is generally adapted to local environmental conditions across its current range in part due to hybridization of two species; (ii) local adaptation to specific climate, soil and resource availability will yield predictable responses to episodic herbivory; and (iii) the ability to cope with a combination of episodic herbivory and increased aridity associated with climate change will be largely based on functional tradeoffs in resource allocation. This review focusses on the potential heritability of plant carbon allocation patterns in Tamarix, focussing on the relative contribution of acquired carbon to non-structural carbohydrate (NSC) pools versus other sinks as the basis for surviving episodic disturbance. Where high aridity and/or poor edaphic position lead to chronic stress, NSC pools may fall below a minimum threshold because of an imbalance between the supply of carbon and its demand by various sinks. Identifying patterns of local adaptation of traits related to resource allocation will improve forecasting of Tamarix population susceptibility to episodic herbivory. PMID:28852513

The numerical and functional responses of a granivorous rodent and the fate of Neotropical tree seeds

USGS Publications Warehouse

Klinger, R.; Rejmanek, M.

2009-01-01

Despite their potential to provide mechanistic explanations of rates of seed dispersal and seed fate, the functional and numerical responses of seed predators have never been explicitly examined within this context. Therefore, we investigated the numerical response of a small-mammal seed predator, Heteromys desmarestianus, to disturbance-induced changes in food availability and evaluated the degree to which removal and fate of seeds of eight tree species in a lowland tropical forest in Belize were related to the functional response of H. desmarestianus to varying seed densities. Mark-recapture trapping was used to estimate abundance of H. desmarestianus in six 0.5-ha grids from July 2000 to September 2002. Fruit availability and seed fate were estimated in each grid, and two experiments nested within the grids were used to determine (1) the form of the functional response for nine levels of fruit density (2-32 fruits/m 2), (2) the removal rate and handling times, and (3) the total proportion of fruits removed. The total proportion of fruits removed was determined primarily by the numerical response of H. desmarestianus to fruit availability, while removal rates and the proportion of seeds eaten or cached were related primarily to the form of the functional response. However, the numerical and functional responses interacted; H. desmarestianus showed strong spatial and temporal numerical responses to total fruit availability, and their density relative to fruit availability resulted in variation in the form of the functional response. Types I, II, and III functional responses were observed, as were density-independent responses, and these responses varied both among and within fruit species. The highest proportions of fruits were eaten when the Type III functional response was detected, which was when fruit availability was high relative to H. desmarestianus population density. Numerous idiosyncratic influences on seed fate have been documented, but our results indicate that shifts in the numerical and functional responses of seed predators to seasonal and interannual variation in seed availability potentially provide a general mechanistic explanation for patterns of removal and fate for vertebrate-dispersed seeds. ?? 2009 by the Ecological Society of America.

Coral bleaching response index: a new tool to standardize and compare susceptibility to thermal bleaching.

PubMed

Swain, Timothy D; Vega-Perkins, Jesse B; Oestreich, William K; Triebold, Conrad; DuBois, Emily; Henss, Jillian; Baird, Andrew; Siple, Margaret; Backman, Vadim; Marcelino, Luisa

2016-07-01

As coral bleaching events become more frequent and intense, our ability to predict and mitigate future events depends upon our capacity to interpret patterns within previous episodes. Responses to thermal stress vary among coral species; however the diversity of coral assemblages, environmental conditions, assessment protocols, and severity criteria applied in the global effort to document bleaching patterns creates challenges for the development of a systemic metric of taxon-specific response. Here, we describe and validate a novel framework to standardize bleaching response records and estimate their measurement uncertainties. Taxon-specific bleaching and mortality records (2036) of 374 coral taxa (during 1982-2006) at 316 sites were standardized to average percent tissue area affected and a taxon-specific bleaching response index (taxon-BRI) was calculated by averaging taxon-specific response over all sites where a taxon was present. Differential bleaching among corals was widely variable (mean taxon-BRI = 25.06 ± 18.44%, ±SE). Coral response may differ because holobionts are biologically different (intrinsic factors), they were exposed to different environmental conditions (extrinsic factors), or inconsistencies in reporting (measurement uncertainty). We found that both extrinsic and intrinsic factors have comparable influence within a given site and event (60% and 40% of bleaching response variance of all records explained, respectively). However, when responses of individual taxa are averaged across sites to obtain taxon-BRI, differential response was primarily driven by intrinsic differences among taxa (65% of taxon-BRI variance explained), not conditions across sites (6% explained), nor measurement uncertainty (29% explained). Thus, taxon-BRI is a robust metric of intrinsic susceptibility of coral taxa. Taxon-BRI provides a broadly applicable framework for standardization and error estimation for disparate historical records and collection of novel data, allowing for unprecedented accuracy in parameterization of mechanistic and predictive models and conservation plans. © 2016 John Wiley & Sons Ltd.

Is Response to Fire Influenced by Dietary Specialization and Mobility? A Comparative Study with Multiple Animal Assemblages

PubMed Central

Bros, Vicenç; Brotons, Lluís; De Mas, Eva; Herraiz, Joan A.; Herrando, Sergi; Miño, Àngel; Olmo-Vidal, Josep M.; Quesada, Javier; Ribes, Jordi; Sabaté, Santiago; Sauras-Yera, Teresa; Serra, Antoni; Vallejo, V. Ramón; Viñolas, Amador

2014-01-01

Fire is a major agent involved in landscape transformation and an indirect cause of changes in species composition. Responses to fire may vary greatly depending on life histories and functional traits of species. We have examined the taxonomic and functional responses to fire of eight taxonomic animal groups displaying a gradient of dietary and mobility patterns: Gastropoda, Heteroptera, Formicidae, Coleoptera, Araneae, Orthoptera, Reptilia and Aves. The fieldwork was conducted in a Mediterranean protected area on 3 sites (one unburnt and two burnt with different postfire management practices) with five replicates per site. We collected information from 4606 specimens from 274 animal species. Similarity in species composition and abundance between areas was measured by the Bray-Curtis index and ANOSIM, and comparisons between animal and plant responses by Mantel tests. We analyze whether groups with the highest percentage of omnivorous species, these species being more generalist in their dietary habits, show weak responses to fire (i.e. more similarity between burnt and unburnt areas), and independent responses to changes in vegetation. We also explore how mobility, i.e. dispersal ability, influences responses to fire. Our results demonstrate that differences in species composition and abundance between burnt and unburnt areas differed among groups. We found a tendency towards presenting lower differences between areas for groups with higher percentages of omnivorous species. Moreover, taxa with a higher percentage of omnivorous species had significantly more independent responses of changes in vegetation. High- (e.g. Aves) and low-mobility (e.g. Gastropoda) groups had the strongest responses to fire (higher R scores of the ANOSIM); however, we failed to find a significant general pattern with all the groups according to their mobility. Our results partially support the idea that functional traits underlie the response of organisms to environmental changes caused by fire. PMID:24516616

Is response to fire influenced by dietary specialization and mobility? A comparative study with multiple animal assemblages.

PubMed

Santos, Xavier; Mateos, Eduardo; Bros, Vicenç; Brotons, Lluís; De Mas, Eva; Herraiz, Joan A; Herrando, Sergi; Miño, Àngel; Olmo-Vidal, Josep M; Quesada, Javier; Ribes, Jordi; Sabaté, Santiago; Sauras-Yera, Teresa; Serra, Antoni; Vallejo, V Ramón; Viñolas, Amador

2014-01-01

Fire is a major agent involved in landscape transformation and an indirect cause of changes in species composition. Responses to fire may vary greatly depending on life histories and functional traits of species. We have examined the taxonomic and functional responses to fire of eight taxonomic animal groups displaying a gradient of dietary and mobility patterns: Gastropoda, Heteroptera, Formicidae, Coleoptera, Araneae, Orthoptera, Reptilia and Aves. The fieldwork was conducted in a Mediterranean protected area on 3 sites (one unburnt and two burnt with different postfire management practices) with five replicates per site. We collected information from 4606 specimens from 274 animal species. Similarity in species composition and abundance between areas was measured by the Bray-Curtis index and ANOSIM, and comparisons between animal and plant responses by Mantel tests. We analyze whether groups with the highest percentage of omnivorous species, these species being more generalist in their dietary habits, show weak responses to fire (i.e. more similarity between burnt and unburnt areas), and independent responses to changes in vegetation. We also explore how mobility, i.e. dispersal ability, influences responses to fire. Our results demonstrate that differences in species composition and abundance between burnt and unburnt areas differed among groups. We found a tendency towards presenting lower differences between areas for groups with higher percentages of omnivorous species. Moreover, taxa with a higher percentage of omnivorous species had significantly more independent responses of changes in vegetation. High- (e.g. Aves) and low-mobility (e.g. Gastropoda) groups had the strongest responses to fire (higher R scores of the ANOSIM); however, we failed to find a significant general pattern with all the groups according to their mobility. Our results partially support the idea that functional traits underlie the response of organisms to environmental changes caused by fire.

Coral bleaching response index: a new tool to standardize and compare susceptibility to thermal bleaching

PubMed Central

SWAIN, TIMOTHY D.; VEGA-PERKINS, JESSE B.; OESTREICH, WILLIAM K.; TRIEBOLD, CONRAD; DUBOIS, EMILY; HENSS, JILLIAN; BAIRD, ANDREW; SIPLE, MARGARET; BACKMAN, VADIM; MARCELINO, LUISA

2017-01-01

As coral bleaching events become more frequent and intense, our ability to predict and mitigate future events depends upon our capacity to interpret patterns within previous episodes. Responses to thermal stress vary among coral species; however the diversity of coral assemblages, environmental conditions, assessment protocols, and severity criteria applied in the global effort to document bleaching patterns creates challenges for the development of a systemic metric of taxon-specific response. Here, we describe and validate a novel framework to standardize bleaching response records and estimate their measurement uncertainties. Taxon-specific bleaching and mortality records (2036) of 374 coral taxa (during 1982–2006) at 316 sites were standardized to average percent tissue area affected and a taxon-specific bleaching response index (taxon-BRI) was calculated by averaging taxon-specific response over all sites where a taxon was present. Differential bleaching among corals was widely variable (mean taxon-BRI = 25.06 ± 18.44%, ± SE). Coral response may differ because holobionts are biologically different (intrinsic factors), they were exposed to different environmental conditions (extrinsic factors), or inconsistencies in reporting (measurement uncertainty). We found that both extrinsic and intrinsic factors have comparable influence within a given site and event (60% and 40% of bleaching response variance of all records explained, respectively). However, when responses of individual taxa are averaged across sites to obtain taxon-BRI, differential response was primarily driven by intrinsic differences among taxa (65% of taxon-BRI variance explained), not conditions across sites (6% explained), nor measurement uncertainty (29% explained). Thus, taxon-BRI is a robust metric of intrinsic susceptibility of coral taxa. Taxon-BRI provides a broadly applicable framework for standardization and error estimation for disparate historical records and collection of novel data, allowing for unprecedented accuracy in parameterization of mechanistic and predictive models and conservation plans. PMID:27074334

Steady-state multifocal visual evoked potential (ssmfVEP) using dartboard stimulation as a possible tool for objective visual field assessment.

PubMed

Horn, Folkert K; Selle, Franziska; Hohberger, Bettina; Kremers, Jan

2016-02-01

To investigate whether a conventional, monitor-based multifocal visual evoked potential (mfVEP) system can be used to record steady-state mfVEP (ssmfVEP) in healthy subjects and to study the effects of temporal frequency, electrode configuration and alpha waves. Multifocal pattern reversal VEP measurements were performed at 58 dartboard fields using VEP recording equipment. The responses were measured using m-sequences with four pattern reversals per m-step. Temporal frequencies were varied between 6 and 15 Hz. Recordings were obtained from nine normal subjects with a cross-shaped, four-electrode device (two additional channels were derived). Spectral analyses were performed on the responses at all locations. The signal to noise ratio (SNR) was computed for each response using the signal amplitude at the reversal frequency and the noise at the neighbouring frequencies. Most responses in the ssmfVEP were significantly above noise. The SNR was largest for an 8.6-Hz reversal frequency. The individual alpha electroencephalogram (EEG) did not strongly influence the results. The percentage of the records in which each of the 6 channels had the largest SNR was between 10.0 and 25.2 %. Our results in normal subjects indicate that reliable mfVEP responses can be achieved by steady-state stimulation using a conventional dartboard stimulator and multi-channel electrode device. The ssmfVEP may be useful for objective visual field assessment as spectrum analysis can be used for automated evaluation of responses. The optimal reversal frequency is 8.6 Hz. Alpha waves have only a minor influence on the analysis. Future studies must include comparisons with conventional mfVEP and psychophysical visual field tests.

Hemocyanins Stimulate Innate Immunity by Inducing Different Temporal Patterns of Proinflammatory Cytokine Expression in Macrophages.

PubMed

Zhong, Ta-Ying; Arancibia, Sergio; Born, Raimundo; Tampe, Ricardo; Villar, Javiera; Del Campo, Miguel; Manubens, Augusto; Becker, María Inés

2016-06-01

Hemocyanins induce a potent Th1-dominant immune response with beneficial clinical outcomes when used as a carrier/adjuvant in vaccines and nonspecific immunostimulant in cancer. However, the mechanisms by which hemocyanins trigger innate immune responses, leading to beneficial adaptive immune responses, are unknown. This response is triggered by a proinflammatory signal from various components, of which macrophages are an essential part. To understand how these proteins influence macrophage response, we investigated the effects of mollusks hemocyanins with varying structural and immunological properties, including hemocyanins from Concholepas concholepas, Fissurella latimarginata, and Megathura crenulata (keyhole limpet hemocyanin), on cultures of peritoneal macrophages. Hemocyanins were phagocytosed and slowly processed. Analysis of this process showed differential gene expression along with protein levels of proinflammatory markers, including IL-1β, IL-6, IL-12p40, and TNF-α. An extended expression analysis of 84 cytokines during a 24-h period showed a robust proinflammatory response for F. latimarginata hemocyanin in comparison with keyhole limpet hemocyanin and C. concholepas hemocyanin, which was characterized by an increase in the transcript levels of M1 cytokines involved in leukocyte recruitment. These cytokine genes included chemokines (Cxcl1, Cxcl3, Cxcl5, Ccl2, and Ccl3), ILs (Il1b and Ifng), growth factors (Csf2 and Csf3), and TNF family members (Cd40lg). The protein levels of certain cytokines were increased. However, every hemocyanin maintains downregulated key M2 cytokine genes, including Il4 and Il5 Collectively, our data demonstrate that hemocyanins are able to trigger the release of proinflammatory factors with different patterns of cytokine expression, suggesting differential signaling pathways and transcriptional network mechanisms that lead to the activation of M1-polarized macrophages. Copyright © 2016 by The American Association of Immunologists, Inc.

Hemocyanins Stimulate Innate Immunity by Inducing Different Temporal Patterns of Proinflammatory Cytokine Expression in Macrophages

PubMed Central

Zhong, Ta-Ying; Arancibia, Sergio; Born, Raimundo; Tampe, Ricardo; Villar, Javiera; Del Campo, Miguel; Manubens, Augusto

2016-01-01

Hemocyanins induce a potent Th1-dominant immune response with beneficial clinical outcomes when used as a carrier/adjuvant in vaccines and nonspecific immunostimulant in cancer. However, the mechanisms by which hemocyanins trigger innate immune responses, leading to beneficial adaptive immune responses, are unknown. This response is triggered by a proinflammatory signal from various components, of which macrophages are an essential part. To understand how these proteins influence macrophage response, we investigated the effects of mollusks hemocyanins with varying structural and immunological properties, including hemocyanins from Concholepas concholepas, Fissurella latimarginata, and Megathura crenulata (keyhole limpet hemocyanin), on cultures of peritoneal macrophages. Hemocyanins were phagocytosed and slowly processed. Analysis of this process showed differential gene expression along with protein levels of proinflammatory markers, including IL-1β, IL-6, IL-12p40, and TNF-α. An extended expression analysis of 84 cytokines during a 24-h period showed a robust proinflammatory response for F. latimarginata hemocyanin in comparison with keyhole limpet hemocyanin and C. concholepas hemocyanin, which was characterized by an increase in the transcript levels of M1 cytokines involved in leukocyte recruitment. These cytokine genes included chemokines (Cxcl1, Cxcl3, Cxcl5, Ccl2, and Ccl3), ILs (Il1b and Ifng), growth factors (Csf2 and Csf3), and TNF family members (Cd40lg). The protein levels of certain cytokines were increased. However, every hemocyanin maintains downregulated key M2 cytokine genes, including Il4 and Il5. Collectively, our data demonstrate that hemocyanins are able to trigger the release of proinflammatory factors with different patterns of cytokine expression, suggesting differential signaling pathways and transcriptional network mechanisms that lead to the activation of M1-polarized macrophages. PMID:27183578

Bone microstructure and developmental plasticity in birds and other dinosaurs.

PubMed

Starck, J Matthias; Chinsamy, Anusuya

2002-12-01

Patterns of bone microstructure have frequently been used to deduce dynamics and processes of growth in extant and fossil tetrapods. Often, the various types of primary bone tissue have been associated with different bone deposition rates and more recently such deductions have extended to patterns observed in dinosaur bone microstructure. These previous studies are challenged by the findings of the current research, which integrates an experimental neontological approach and a paleontological comparison. We use tetracycline labeling and morphometry to study the variability of bone deposition rates in Japanese quail (Coturnix japonica) growing under different experimental conditions. We compare resulting patterns in bone microstructure with those found in fossil birds and other dinosaurs. We found that a single type of primary bone varies significantly in rates of growth in response to environmental conditions. Ranging between 10-50 microm per day, rates of growth overlap with the full range of bone deposition rates that were previously associated with different patterns of bone histology. Bone formation rate was significantly affected by environmental/experimental conditions, skeletal element, and age. In the quail, the experimental conditions did not result in formation of lines of arrested growth (LAGs). Because of the observed variation of bone deposition rates in response to variation in environmental conditions, we conclude that bone deposition rates measured in extant birds cannot simply be extrapolated to their fossil relatives. Additionally, we observe the variable incidence of LAGs and annuli among several dinosaur species, including fossil birds, extant sauropsids, as well as nonmammalian synapsids, and some extant mammals. This suggests that the ancestral condition of the response of bone to environmental conditions was variable. We propose that such developmental plasticity in modern birds may be reduced in association with the shortened developmental time during the later evolution of the ornithurine birds. Copyright 2002 Wiley-Liss, Inc.

Maternal Dietary Patterns and Fetal Growth: A Large Prospective Cohort Study in China.

PubMed

Lu, Min-Shan; Chen, Qiao-Zhu; He, Jian-Rong; Wei, Xue-Ling; Lu, Jin-Hua; Li, Sheng-Hui; Wen, Xing-Xuan; Chan, Fan-Fan; Chen, Nian-Nian; Qiu, Lan; Mai, Wei-Bi; Zhang, Rui-Fang; Hu, Cui-Yue; Xia, Hui-Min; Qiu, Xiu

2016-04-28

There was limited evidence revealing the association of Chinese maternal dietary patterns with fetal growth. We aimed to examine the relationship of maternal dietary patterns during pregnancy to neonatal birth weight and birth weight for gestational age in a Chinese population. A total of 6954 mother-child pairs were included from the Born in Guangzhou Cohort Study. Maternal diet during pregnancy was assessed using a self-administered food frequency questionnaire. Cluster analysis was used to identify dietary patterns. The following six dietary patterns were identified: "Cereals, eggs, and Cantonese soups" (n 1026, 14.8%), "Dairy" (n 1020, 14.7%), "Fruits, nuts, and Cantonese desserts" (n 799, 11.5%), "Meats" (n 1066, 15.3%), "Vegetables" (n 1383, 19.9%), and "Varied" (n 1224, 17.6%). The mean neonatal birth weight Z scores of women in the above patterns were 0.02, 0.07, 0.20, 0.01, 0.06, and 0.14, respectively. Women in the "Fruits, nuts, and Cantonese desserts" and "Varied" groups had significantly heavier infants compared with those in the "Cereals, eggs, and Cantonese soups" group. Compared with women in the "Cereals, eggs, and Cantonese soups" group, those in the "Varied" group had marginally significantly lower odds of having a small-for-gestational age (SGA) infant after adjustment for other confounders (OR 0.77, 95% CI 0.57, 1.04, p = 0.08). These findings suggest that compared to a traditional Cantonese diet high in cereals, eggs, and Cantonese soups, a diet high in fruits, nuts, and Cantonese desserts might be associated with a higher birth weight, while a varied diet might be associated with a greater birth weight and also a decreased risk of having a SGA baby.

A Study on the Response of Non-photosynthetic Vegetation (NPV) towards the Anomalies of Climate in the Southwestern U.S.

NASA Astrophysics Data System (ADS)

Jia, S.; Okin, G. S.

2014-12-01

Non-photosynthetic vegetation (NPV), including the standing dead leaves and trunks of plants, is not only a crucial component of aboveground biomass in the dry ecosystems but also an effective indicator of drought, since the photosynthetic plants (PV) usually degrade to NPV after drought. With the multiple-endmember spectral mixture (MESMA) analysis, it is possible to extract the NPV coverage to a selected baseline date from MODIS MOD43 NBAR data. In this study, we used a baseline image derived based on JHU Spectral Library to obtain the NPV, PV and bare soil of southwest U.S. from 2000 to 2012. To investigate the response of NPV, we then calculated the lagged and non-lagged correlation between the anomalies of land cover and climate variables. The major land use categories are also employed to investigate the spatial pattern of the response. The more significant correlation between NPV or PV and precipitation than temperature indicates the importance of moisture in the study site. In addition, there is an asymmetric response between NPV to the drought and the increased precipitation. In drier inland, the most significant response of NPV after a deficit of precipitation occurs later than after an increase. The increase of temperature, especially under the deficits of moisture, facilitates the presence of NPV with lag, which is due to the response time of detectable withering of PV. The response of NPV also varies between the different land cover categories. In southwest U.S., the NPV from shrubs and grassland have more sensitive feedbacks on the dynamics of climate than wetter region. The nature of the ecosystems can partly explain the difference, but finer scale studies are necessary for further investigation of specific regions. Considering the increase of drought in southwest U.S., obtaining a better understanding on the response of vegetation is crucial to further evaluate its impacts on the dry ecosystems. This study provides a perspective by examining NPV, another direct indicator of drought. For further studies, temporal and spatial patterns of NPV response to the climate need more scrutiny, such as the spatial pattern of the lags, hotspots of change, and regional-specific feedbacks. Different indicators of extreme events, such as the U.S. Drought Monitor may also be employed to provide more direct evaluation.

Modeling the Effects of HER/ErbB1-3 Coexpression on Receptor Dimerization and Biological Response

PubMed Central

Shankaran, Harish; Wiley, H. Steven; Resat, Haluk

2006-01-01

The human epidermal growth factor receptor (HER/ErbB) system comprises the epidermal growth factor receptor (EGFR/HER1) and three other homologs, namely HERs 2–4. This receptor system plays a critical role in cell proliferation and differentiation and receptor overexpression has been associated with poor prognosis in cancers of the epithelium. Here, we examine the effect of coexpressing varying levels of HERs 1–3 on the receptor dimerization patterns using a detailed kinetic model for HER/ErbB dimerization and trafficking. Our results indicate that coexpression of EGFR with HER2 or HER3 biases signaling to the cell surface and retards signal downregulation. In addition, simultaneous coexpression of HERs 1–3 leads to an abundance of HER2-HER3 heterodimers, which are known to be potent inducers of cell growth and transformation. Our new approach to use parameter dependence analysis in experimental design reveals that measurements of HER3 phosphorylation and HER2 internalization ratio may prove to be especially useful for the estimation of critical model parameters. Further, we examine the effect of receptor dimerization patterns on biological response using a simple phenomenological model. Results indicate that coexpression of EGFR with HER2 and HER3 at low to moderate levels may enable cells to match the response of a high HER2 expresser. PMID:16533841

Effects of stimulus response compatibility on covert imitation of vowels.

PubMed

Adank, Patti; Nuttall, Helen; Bekkering, Harold; Maegherman, Gwijde

2018-03-13

When we observe someone else speaking, we tend to automatically activate the corresponding speech motor patterns. When listening, we therefore covertly imitate the observed speech. Simulation theories of speech perception propose that covert imitation of speech motor patterns supports speech perception. Covert imitation of speech has been studied with interference paradigms, including the stimulus-response compatibility paradigm (SRC). The SRC paradigm measures covert imitation by comparing articulation of a prompt following exposure to a distracter. Responses tend to be faster for congruent than for incongruent distracters; thus, showing evidence of covert imitation. Simulation accounts propose a key role for covert imitation in speech perception. However, covert imitation has thus far only been demonstrated for a select class of speech sounds, namely consonants, and it is unclear whether covert imitation extends to vowels. We aimed to demonstrate that covert imitation effects as measured with the SRC paradigm extend to vowels, in two experiments. We examined whether covert imitation occurs for vowels in a consonant-vowel-consonant context in visual, audio, and audiovisual modalities. We presented the prompt at four time points to examine how covert imitation varied over the distracter's duration. The results of both experiments clearly demonstrated covert imitation effects for vowels, thus supporting simulation theories of speech perception. Covert imitation was not affected by stimulus modality and was maximal for later time points.

Interactions of landscape disturbances and climate change dictate ecological pattern and process: spatial modeling of wildfire, insect, and disease dynamics under future climates

USGS Publications Warehouse

Loehman, Rachel A.; Keane, Robert E.; Holsinger, Lisa M.; Wu, Zhiwei

2016-01-01

ContextInteractions among disturbances, climate, and vegetation influence landscape patterns and ecosystem processes. Climate changes, exotic invasions, beetle outbreaks, altered fire regimes, and human activities may interact to produce landscapes that appear and function beyond historical analogs.ObjectivesWe used the mechanistic ecosystem-fire process model FireBGCv2 to model interactions of wildland fire, mountain pine beetle (Dendroctonus ponderosae), and white pine blister rust (Cronartium ribicola) under current and future climates, across three diverse study areas.MethodsWe assessed changes in tree basal area as a measure of landscape response over a 300-year simulation period for the Crown of the Continent in north-central Montana, East Fork of the Bitterroot River in western Montana, and Yellowstone Central Plateau in western Wyoming, USA.ResultsInteracting disturbances reduced overall basal area via increased tree mortality of host species. Wildfire decreased basal area more than beetles or rust, and disturbance interactions modeled under future climate significantly altered landscape basal area as compared with no-disturbance and current climate scenarios. Responses varied among landscapes depending on species composition, sensitivity to fire, and pathogen and beetle suitability and susceptibility.ConclusionsUnderstanding disturbance interactions is critical for managing landscapes because forest responses to wildfires, pathogens, and beetle attacks may offset or exacerbate climate influences, with consequences for wildlife, carbon, and biodiversity.

DIFFERENT TYPES OF INTIMATE PARTNER VIOLENCE LIKELY REQUIRE DIFFERENT TYPES OF APPROACHES TO PREVENTION: A RESPONSE TO BUZAWA AND BUZAWA

PubMed Central

Matjasko, Jennifer L.; Niolon, Phyllis Holditch; Valle, Linda Anne

2018-01-01

Buzawa and Buzawa (this issue) assert that there are different typologies of intimate partner violence (IPV) defined by the extent to which the violence is part of a general pattern of coercive control. They center their discussion on batterers, who are understood to be responsible for the most severe forms of abuse and injury. Economic factors are believed to be “only a weak predictor of violence” in these cases. Thus, they argue that, in the face of severe budget constraints, there is a need to focus on the chronically violent offender and support-coordinated services for IPV victims. We agree that there are different types of IPV distinguishable by the extent to which the violence is occurring within a pattern of general coercive control and that each type has different risk and protective factors. We also agree economic factors interact with other factors in complex ways and vary in the extent to which they predict different types of IPV. However, we argue economic factors should not be ignored as an important strategy in preventing situational couple violence (SCV) and helping victims to escape from intimate terrorists (ITs). Relying on response (rather than prevention) strategies, such as coordinated community response—for which there is limited evidence of effectiveness—is unlikely to significantly impact rates of all types of IPV. PMID:29853730

Post-eclosion odor experience modifies olfactory receptor neuron coding in Drosophila

PubMed Central

Iyengar, Atulya; Chakraborty, Tuhin Subhra; Goswami, Sarit Pati; Wu, Chun-Fang; Siddiqi, Obaid

2010-01-01

Olfactory responses of Drosophila undergo pronounced changes after eclosion. The flies develop attraction to odors to which they are exposed and aversion to other odors. Behavioral adaptation is correlated with changes in the firing pattern of olfactory receptor neurons (ORNs). In this article, we present an information-theoretic analysis of the firing pattern of ORNs. Flies reared in a synthetic odorless medium were transferred after eclosion to three different media: (i) a synthetic medium relatively devoid of odor cues, (ii) synthetic medium infused with a single odorant, and (iii) complex cornmeal medium rich in odors. Recordings were made from an identified sensillum (type II), and the Jensen–Shannon divergence (DJS) was used to assess quantitatively the differences between ensemble spike responses to different odors. Analysis shows that prolonged exposure to ethyl acetate and several related esters increases sensitivity to these esters but does not improve the ability of the fly to distinguish between them. Flies exposed to cornmeal display varied sensitivity to these odorants and at the same time develop greater capacity to distinguish between odors. Deprivation of odor experience on an odorless synthetic medium leads to a loss of both sensitivity and acuity. Rich olfactory experience thus helps to shape the ORNs response and enhances its discriminative power. The experiments presented here demonstrate an experience-dependent adaptation at the level of the receptor neuron. PMID:20448199

Post-eclosion odor experience modifies olfactory receptor neuron coding in Drosophila.

PubMed

Iyengar, Atulya; Chakraborty, Tuhin Subhra; Goswami, Sarit Pati; Wu, Chun-Fang; Siddiqi, Obaid

2010-05-25

Olfactory responses of Drosophila undergo pronounced changes after eclosion. The flies develop attraction to odors to which they are exposed and aversion to other odors. Behavioral adaptation is correlated with changes in the firing pattern of olfactory receptor neurons (ORNs). In this article, we present an information-theoretic analysis of the firing pattern of ORNs. Flies reared in a synthetic odorless medium were transferred after eclosion to three different media: (i) a synthetic medium relatively devoid of odor cues, (ii) synthetic medium infused with a single odorant, and (iii) complex cornmeal medium rich in odors. Recordings were made from an identified sensillum (type II), and the Jensen-Shannon divergence (D(JS)) was used to assess quantitatively the differences between ensemble spike responses to different odors. Analysis shows that prolonged exposure to ethyl acetate and several related esters increases sensitivity to these esters but does not improve the ability of the fly to distinguish between them. Flies exposed to cornmeal display varied sensitivity to these odorants and at the same time develop greater capacity to distinguish between odors. Deprivation of odor experience on an odorless synthetic medium leads to a loss of both sensitivity and acuity. Rich olfactory experience thus helps to shape the ORNs response and enhances its discriminative power. The experiments presented here demonstrate an experience-dependent adaptation at the level of the receptor neuron.

Guided participation in cultural activity by toddlers and caregivers.

PubMed

Rogoff, B; Mistry, J; Göncü, A; Mosier, C

1993-01-01

In this Monograph, we examine how toddlers and their caregivers from four cultural communities collaborate in shared activities. We focus both on similarities across communities in processes of guided participation--structuring children's participation and bridging between their understanding and that of their caregivers--and on differences in how guided participation occurs. We examine the idea that a key cultural difference entails who is responsible for learning--whether adults take this responsibility by structuring teaching situations or whether children take responsibility for learning through observation and through participating in adult activities with caregivers' support. We speculate that these two patterns relate to cultural variation in the segregation of children from adult activities of their community and in emphasis on formal schooling. The four communities of our study vary along these lines as well as in other ways: a Mayan Indian town in Guatemala, a middle-class urban group in the United States, a tribal village in India, and a middle-class urban neighborhood in Turkey. In each community, we visited the families of 14 toddlers (aged 12-24 months) for an interview that was focused on child-rearing practices, which included observations of caregivers helping the toddlers operate novel objects spontaneously during adult activities. Results are based on systematic analysis of patterns of communication and attention in each family in each community, combining the tools of ethnographic description, graphic analysis, and statistics.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of contingency awareness on neural, electrodermal and evaluative responses during fear conditioning

PubMed Central

Merz, Christian J.; Klucken, Tim; Schweckendiek, Jan; Vaitl, Dieter; Wolf, Oliver T.; Stark, Rudolf

2011-01-01

In an fMRI study, effects of contingency awareness on conditioned responses were assessed in three groups comprising 118 subjects. A differential fear-conditioning paradigm with visual conditioned stimuli, an electrical unconditioned stimulus and two distractors was applied. The instructed aware group was informed about the contingencies, whereas the distractors prevented contingency detection in the unaware group. The third group (learned aware) was not informed about the contingencies, but learned them despite the distractors. Main effects of contingency awareness on conditioned responses emerged in several brain structures. Post hoc tests revealed differential dorsal anterior cingulate, insula and ventral striatum responses in aware conditioning only, whereas the amygdala was activated independent of contingency awareness. Differential responses of the hippocampus were specifically observed in learned aware subjects, indicating a role in the development of contingency awareness. The orbitofrontal cortex showed varying response patterns: lateral structures showed higher responses in instructed aware than unaware subjects, the opposite was true for medial parts. Conditioned subjective and electrodermal responses emerged only in the two aware groups. These results confirm the independence of conditioned amygdala responses from contingency awareness and indicate specific neural circuits for different aspects of fear acquisition in unaware, learned aware and instructed aware subjects. PMID:20693389

Foliar damage beyond species distributions is partly explained by distance dependent interactions with natural enemies.

PubMed

Katz, Daniel S W; Ibáñez, Inés

2016-09-01

Plant distributions are expected to shift in response to climate change, and range expansion dynamics will be shaped by the performance of individuals at the colonizing front. These plants will encounter new biotic communities beyond their range edges, and the net outcome of these encounters could profoundly affect colonization success. However, little is known about how biotic interactions vary across range edges and this has hindered efforts to predict changes in species distributions in response to climate change. In contrast, a rich literature documents how biotic interactions within species ranges vary according to distance to and density of conspecific individuals. Here, we test whether this framework can be extended to explain how biotic interactions differ beyond range edges, where conspecific adults are basically absent. To do so, we planted seven species of trees along a 450-km latitudinal gradient that crossed the current distributional range of five of these species and monitored foliar disease and invertebrate herbivory over 5 yr. Foliar disease and herbivory were analyzed as a function of distance to and density of conspecific and congeneric trees at several spatial scales. We found that within species ranges foliar disease was lower for seedlings that were farther from conspecific adults for Acer rubrum, Carya glabra, Quercus alba, and Robinia pseudoacacia. Beyond range edges, there was even less foliar disease for C. glabra, Q. alba, and R. pseudoacacia (A. rubrum was not planted outside its range). Liriodendron tulipifera did not experience reduced disease within or beyond its range. In contrast, Quercus velutina displayed significant but idiosyncratic patterns in disease at varying distances from conspecifics. Patterns of distance dependent herbivory across spatial scales was generally weak and in some cases negative (i.e., seedlings farther from conspecific adults had more herbivory). Overall, we conclude that differences in biotic interactions across range edges can be thought of as a spatial extension to the concept of distance dependent biotic interactions. This framework also provides the basis for general predictions of how distance dependent biotic interactions will change across range edges in other systems. © 2016 by the Ecological Society of America.

Fault detection in reciprocating compressor valves under varying load conditions

NASA Astrophysics Data System (ADS)

Pichler, Kurt; Lughofer, Edwin; Pichler, Markus; Buchegger, Thomas; Klement, Erich Peter; Huschenbett, Matthias

2016-03-01

This paper presents a novel approach for detecting cracked or broken reciprocating compressor valves under varying load conditions. The main idea is that the time frequency representation of vibration measurement data will show typical patterns depending on the fault state. The problem is to detect these patterns reliably. For the detection task, we make a detour via the two dimensional autocorrelation. The autocorrelation emphasizes the patterns and reduces noise effects. This makes it easier to define appropriate features. After feature extraction, classification is done using logistic regression and support vector machines. The method's performance is validated by analyzing real world measurement data. The results will show a very high detection accuracy while keeping the false alarm rates at a very low level for different compressor loads, thus achieving a load-independent method. The proposed approach is, to our best knowledge, the first automated method for reciprocating compressor valve fault detection that can handle varying load conditions.

Cell segmentation in time-lapse fluorescence microscopy with temporally varying sub-cellular fusion protein patterns.

PubMed

Bunyak, Filiz; Palaniappan, Kannappan; Chagin, Vadim; Cardoso, M

2009-01-01

Fluorescently tagged proteins such as GFP-PCNA produce rich dynamically varying textural patterns of foci distributed in the nucleus. This enables the behavioral study of sub-cellular structures during different phases of the cell cycle. The varying punctuate patterns of fluorescence, drastic changes in SNR, shape and position during mitosis and abundance of touching cells, however, require more sophisticated algorithms for reliable automatic cell segmentation and lineage analysis. Since the cell nuclei are non-uniform in appearance, a distribution-based modeling of foreground classes is essential. The recently proposed graph partitioning active contours (GPAC) algorithm supports region descriptors and flexible distance metrics. We extend GPAC for fluorescence-based cell segmentation using regional density functions and dramatically improve its efficiency for segmentation from O(N(4)) to O(N(2)), for an image with N(2) pixels, making it practical and scalable for high throughput microscopy imaging studies.

Tactile learning and the individual evaluation of the reward in honey bees (Apis mellifera L.).

PubMed

Scheiner, R; Erber, J; Page, R E

1999-07-01

Using the proboscis extension response we conditioned pollen and nectar foragers of the honey bee (Apis mellifera L.) to tactile patterns under laboratory conditions. Pollen foragers demonstrated better acquisition, extinction, and reversal learning than nectar foragers. We tested whether the known differences in response thresholds to sucrose between pollen and nectar foragers could explain the observed differences in learning and found that nectar foragers with low response thresholds performed better during acquisition and extinction than ones with higher thresholds. Conditioning pollen and nectar foragers with similar response thresholds did not yield differences in their learning performance. These results suggest that differences in the learning performance of pollen and nectar foragers are a consequence of differences in their perception of sucrose. Furthermore, we analysed the effect which the perception of sucrose reward has on associative learning. Nectar foragers with uniform low response thresholds were conditioned using varying concentrations of sucrose. We found significant positive correlations between the concentrations of the sucrose rewards and the performance during acquisition and extinction. The results are summarised in a model which describes the relationships between learning performance, response threshold to sucrose, concentration of sucrose and the number of rewards.

Plant defenses against parasitic plants show similarities to those induced by herbivores and pathogens.

PubMed

Runyon, Justin B; Mescher, Mark C; De Moraes, Consuelo M

2010-08-01

Herbivores and pathogens come quickly to mind when one thinks of the biotic challenges faced by plants. Important but less appreciated enemies are parasitic plants, which can have important consequences for the fitness and survival of their hosts. Our knowledge of plant perception, signaling, and response to herbivores and pathogens has expanded rapidly in recent years, but information is generally lacking for parasitic species. In a recent paper we reported that some of the same defense responses induced by herbivores and pathogens--notably increases in jasmonic acid (JA), salicylic acid (SA), and a hypersensitive-like response (HLR)--also occur in tomato plants upon attack by the parasitic plant Cuscuta pentagona (field dodder). Parasitism induced a distinct pattern of JA and SA accumulation, and growth trials using genetically-altered tomato hosts suggested that both JA and SA govern effective defenses against the parasite, though the extent of the response varied with host plant age. Here we discuss similarities between the induced responses we observed in response to Cuscuta parasitism to those previously described for herbivores and pathogens and present new data showing that trichomes should be added to the list of plant defenses that act against multiple enemies and across Kingdoms.

Characterizing the "Time of Emergence" of Air Quality Climate Penalties

NASA Astrophysics Data System (ADS)

Rothenberg, D. A.; Garcia-Menendez, F.; Monier, E.; Solomon, S.; Selin, N. E.

2017-12-01

By driving not only local changes in temperature, but also precipitation and regional-scale changes in seasonal circulation patterns, climate change can directly and indirectly influence changes in air quality and its extremes. These changes - often referred to as "climate penalties" - can have important implications for human health, which is often targeted when assessing the potential co-benefits of climate policy. But because climate penalties are driven by slow, spatially-varying, temporal changes in the climate system, their emergence in the real world should also have a spatio-temporal component following regional variability in background air quality. In this work, we attempt to estimate the spatially-varying "time of emergence" of climate penalty signals by using an ensemble modeling framework based on the MIT Integrated Global System Model (MIT IGSM). With this framework we assess three climate policy scenarios assuming three different underlying climate sensitivities, and conduct a 5-member ensemble for each case to capture internal variability within the model. These simulations are used to drive offline chemical transport modeling (using CAM-Chem and GEOS-Chem). In these simulations, we find that the air quality response to climate change can vary dramatically across different regions of the globe. To analyze these regionally-varying climate signals, we employ a hierarchical clustering technique to identify regions with similar seasonal patterns of air quality change. Our simulations suggest that the earliest emergence of ozone climate penalties would occur in Southern Europe (by 2035), should the world neglect climate change and rely on a "business-as-usual" emissions policy. However, even modest climate policy dramatically pushes back the time of emergence of these penalties - to beyond 2100 - across most of the globe. The emergence of climate-forced changes in PM2.5 are much more difficult to detect, partially owing to the large role that changes in the frequency and spatial distribution of precipitation play in limiting the accumulation and duration of particulate pollution episodes.

Genome-wide Identification and analysis of the stress-resistance function of the TPS (Trehalose-6-Phosphate Synthase) gene family in cotton.

PubMed

Mu, Min; Lu, Xu-Ke; Wang, Jun-Juan; Wang, De-Long; Yin, Zu-Jun; Wang, Shuai; Fan, Wei-Li; Ye, Wu-Wei

2016-03-18

Trehalose (a-D-glucopyranosyl a-D-glucopyranoside) is a nonreducing disaccharide and is widely distributed in bacteria, fungi, algae, plants and invertebrates. In the study, the identification of trehalose-6-phosphate synthase (TPS) genes stress-related in cotton, and the genetic structure analysis and molecular evolution analysis of TPSs were conducted with bioinformatics methods, which could lay a foundation for further research of TPS functions in cotton. The genome information of Gossypium raimondii (group D), G. arboreum L. (group A), and G. hirsutum L. (group AD) was used in the study. Fifty-three TPSs were identified comprising 15 genes in group D, 14 in group A, and 24 in group AD. Bioinformatics methods were used to analyze the genetic structure and molecular evolution of TPSs. Real-time PCR analysis was performed to investigate the expression patterns of gene family members. All TPS family members in cotton can be divided into two subfamilies: Class I and Class II. The similarity of the TPS sequence is high within the same species and close within their family relatives. The genetic structures of two TPS subfamily members are different, with more introns and a more complicated gene structure in Class I. There is a TPS domain(Glyco transf_20) at the N-terminal in all TPS family members and a TPP domain(Trehalose_PPase) at the C-terminal in all except GrTPS6, GhTPS4, and GhTPS9. All Class II members contain a UDP-forming domain. The responses to environmental stresses showed that stresses could induce the expression of TPSs but the expression patterns vary with different stresses. The distribution of TPSs varies with different species but is relatively uniform on chromosomes. Genetic structure varies with different gene members, and expression levels vary with different stresses and exhibit tissue specificity. The upregulated genes in upland cotton TM-1 is significantly more than that in G. raimondii and G. arboreum L. Shixiya 1.

Optical study of interactions among propagation waves of neural excitation in the rat somatosensory cortex evoked by forelimb and hindlimb stimuli.

PubMed

Hama, Noriyuki; Kawai, Minako; Ito, Shin-Ichi; Hirota, Akihiko

2018-05-01

Multisite optical recording has revealed that the neural excitation wave induced by a sensory stimulation begins at a focus and propagates in the cortex. This wave is considered to be important for computation in the sensory cortex, particularly the integration of sensory information; however, the nature of this wave remains largely unknown. In the present study, we examined the interaction between two waves in the rat sensory cortex induced by hindlimb and forelimb stimuli with different interstimulus intervals. We classified the resultant patterns as follows: 1) the collision of two waves, 2) the hindlimb response being evoked while the forelimb-induced wave is passing the hindlimb focus, and 3) the hindlimb response being evoked after the forelimb-induced wave has passed the hindlimb focus. In pattern 1, the two waves fused into a single wave, but the propagation pattern differed from that predicted by the superimposition of two singly induced propagation courses. In pattern 2, the state of the interaction between the two waves varied depending on the phase of optical signals constituting the forelimb-induced wave around the hindlimb focus. Although no hindlimb-induced wave was observed in the rising phase, the propagating velocity of the forelimb-induced wave increased. At the peak, neither the hindlimb-induced response nor a modulatory effect on the forelimb-induced wave was detected. In pattern 3, the hindlimb-induced wave showed a reduced amplitude and spatial extent. These results indicate that the state of the interaction between waves was strongly influenced by the relative timing of sensory inputs. NEW & NOTEWORTHY Sensory stimulation-induced cortical excitation propagates as a wave and spreads over a wide area of the sensory cortex. To elucidate the characteristics of this relatively unknown phenomenon, we examined the interaction between two individually induced waves in the somatosensory cortex. Either the waves collided or the preceding wave affected the emergence of the following one. Our results indicate that the state of the interaction was strongly influenced by the relative timing of sensory inputs.

Climate variability and human impact on the environment in South America during the last 2000 years: synthesis and perspectives

NASA Astrophysics Data System (ADS)

Flantua, S. G. A.; Hooghiemstra, H.; Vuille, M.; Behling, H.; Carson, J. F.; Gosling, W. D.; Hoyos, I.; Ledru, M. P.; Montoya, E.; Mayle, F.; Maldonado, A.; Rull, V.; Tonello, M. S.; Whitney, B. S.; González-Arango, C.

2015-07-01

An improved understanding of present-day climate variability and change relies on high-quality data sets from the past two millennia. Global efforts to reconstruct regional climate modes are in the process of validating and integrating paleo-proxies. For South America, however, the full potential of vegetation records for evaluating and improving climate models has hitherto not been sufficiently acknowledged due to its unknown spatial and temporal coverage. This paper therefore serves as a guide to high-quality pollen records that capture environmental variability during the last two millennia. We identify the pollen records with the required temporal characteristics for PAGES-2 ka climate modelling and we discuss their sensitivity to the spatial signature of climate modes throughout the continent. Diverse patterns of vegetation response to climate change are observed, with more similar patterns of change in the lowlands and varying intensity and direction of responses in the highlands. Pollen records display local scale responses to climate modes, thus it is necessary to understand how vegetation-climate interactions might diverge under variable settings. Additionally, pollen is an excellent indicator of human impact through time. Evidence for human land use in pollen records is useful for archaeological hypothesis testing and important in distinguishing natural from anthropogenically driven vegetation change. We stress the need for the palynological community to be more familiar with climate variability patterns to correctly attribute the potential causes of observed vegetation dynamics. The LOTRED-SA-2 k initiative provides the ideal framework for the integration of the various paleoclimatic sub-disciplines and paleo-science, thereby jumpstarting and fostering multi-disciplinary research into environmental change on centennial and millennial time scales.

Ion channel mechanisms underlying frequency-firing patterns of the avian nucleus magnocellularis: A computational model

PubMed Central

Lu, Ting; Wade, Kirstie; Sanchez, Jason Tait

2017-01-01

ABSTRACT We have previously shown that late-developing avian nucleus magnocellularis (NM) neurons (embryonic [E] days 19–21) fire action potentials (APs) that resembles a band-pass filter in response to sinusoidal current injections of varying frequencies. NM neurons located in the mid- to high-frequency regions of the nucleus fire preferentially at 75 Hz, but only fire a single onset AP to frequency inputs greater than 200 Hz. Surprisingly, NM neurons do not fire APs to sinusoidal inputs less than 20 Hz regardless of the strength of the current injection. In the present study we evaluated intrinsic mechanisms that prevent AP generation to low frequency inputs. We constructed a computational model to simulate the frequency-firing patterns of NM neurons based on experimental data at both room and near physiologic temperatures. The results from our model confirm that the interaction among low- and high-voltage activated potassium channels (KLVA and KHVA, respectively) and voltage dependent sodium channels (NaV) give rise to the frequency-firing patterns observed in vitro. In particular, we evaluated the regulatory role of KLVA during low frequency sinusoidal stimulation. The model shows that, in response to low frequency stimuli, activation of large KLVA current counterbalances the slow-depolarizing current injection, likely permitting NaV closed-state inactivation and preventing the generation of APs. When the KLVA current density was reduced, the model neuron fired multiple APs per sinusoidal cycle, indicating that KLVA channels regulate low frequency AP firing of NM neurons. This intrinsic property of NM neurons may assist in optimizing response to different rates of synaptic inputs. PMID:28481659

Population-specific responses to light influence herbivory in the understory shrub Lindera benzoin.

PubMed

Mooney, E H; Niesenbaum, R A

2012-12-01

Plants display photosynthetic plasticity in response to variation in light environment, and the extent of this plasticity often varies with genotype, i.e., genotype x environment interaction. Herbivory may also covary with light environment as a result of light-induced changes in photosynthetic traits. For example, greater levels of photoprotective phenolic compounds in high-light environments may reduce host quality to herbivores. We investigated intraspecific variation in photosynthetic responses to light and its consequences for herbivory in the understory shrub, Lindera benzoin (Lauraceae). We transplanted five plants from eight populations (N = 240) into three replicate sun and shade common gardens. Two years after transplantation, we tested for population x light environment interactions in six photosynthesis-related responses: specific leaf area, water content, chlorophyll content, chlorophyll fluorescence (F(0)), maximum quantum yield (F(v)/F(m)), and total phenolics. We assessed seasonal herbivory and consumption by a specialist lepidopteran herbivore (Epimecis hortaria). This allowed us to test for (1) population-specific patterns of photosynthetic acclimation and photoinhibition, (2) population-specific production of phenolics in response to photoinhibition, and (3) population-specific photosynthetic responses that contribute to population x light environment interactions in herbivory. Population X light environment interactions were insignificant in leaf variables but statistically significant for herbivory measured as consumption by E. hortaria. We found similar trends for population x light environment interactions in seasonal herbivory. Total phenolics and minimum chlorophyll fluorescence (F(0)) were significant covariates with herbivory, but their effects depended on light environment and population of origin. High-light environments eliminated differences among populations in how these leaf variables affected herbivory, while population-specific relationships were apparent in the shade. Analysis of total phenolics revealed that they were likely induced by photoinhibition, but that this response varied among the populations we assessed. However, phenolics increased herbivory in L. benzoin, which would limit the fitness value of this protective response to light-induced photoinhibition. Our results suggest that herbivores could affect evolution of photosynthetic plasticity in L. benzoin.

Optical measurement of sound using time-varying laser speckle patterns

NASA Astrophysics Data System (ADS)

Leung, Terence S.; Jiang, Shihong; Hebden, Jeremy

2011-02-01

In this work, we introduce an optical technique to measure sound. The technique involves pointing a coherent pulsed laser beam on the surface of the measurement site and capturing the time-varying speckle patterns using a CCD camera. Sound manifests itself as vibrations on the surface which induce a periodic translation of the speckle pattern over time. Using a parallel speckle detection scheme, the dynamics of the time-varying speckle patterns can be captured and processed to produce spectral information of the sound. One potential clinical application is to measure pathological sounds from the brain as a screening test. We performed experiments to demonstrate the principle of the detection scheme using head phantoms. The results show that the detection scheme can measure the spectra of single frequency sounds between 100 and 2000 Hz. The detection scheme worked equally well in both a flat geometry and an anatomical head geometry. However, the current detection scheme is too slow for use in living biological tissues which has a decorrelation time of a few milliseconds. Further improvements have been suggested.

Discrete simulations of spatio-temporal dynamics of small water bodies under varied stream flow discharges

NASA Astrophysics Data System (ADS)

Daya Sagar, B. S.

2005-01-01

Spatio-temporal patterns of small water bodies (SWBs) under the influence of temporally varied stream flow discharge are simulated in discrete space by employing geomorphologically realistic expansion and contraction transformations. Cascades of expansion-contraction are systematically performed by synchronizing them with stream flow discharge simulated via the logistic map. Templates with definite characteristic information are defined from stream flow discharge pattern as the basis to model the spatio-temporal organization of randomly situated surface water bodies of various sizes and shapes. These spatio-temporal patterns under varied parameters (λs) controlling stream flow discharge patterns are characterized by estimating their fractal dimensions. At various λs, nonlinear control parameters, we show the union of boundaries of water bodies that traverse the water body and non-water body spaces as geomorphic attractors. The computed fractal dimensions of these attractors are 1.58, 1.53, 1.78, 1.76, 1.84, and 1.90, respectively, at λs of 1, 2, 3, 3.46, 3.57, and 3.99. These values are in line with general visual observations.

Earth Surface Patterns in 200 Years (Invited)

NASA Astrophysics Data System (ADS)

Werner, B.

2009-12-01

What kinds of patterns will characterize Earth's surface in 200 years? This question is addressed using a complex systems dynamical framework for distinct levels of description in a hierarchy, in which time scale and spatial extent increase and number of variables decrease with level, and in which levels are connected nonlinearly to each other via self-organization and slaving and linearly to the external environment. Self-organized patterns linking the present to 200 years in the future must be described dynamically on a level with a time scale of centuries. Human-landscape coupling will play a prominent role in the formation of these patterns as population peaks and interactions become nonlinear over these time scales. Three related examples illustrate this approach. First, the response of human-occupied coastlines to rising sea level. Coastlines in wealthy regions develop a spatially varying boom and bust pattern, with response amplified by structures meant to delay the effects of sea level rise. Coastlines in economically disadvantaged regions experience a subdued response, with populations developing a culture of displacement that minimizes human-landscape interactions in a context of scarce resources. Second, the evolution of nation-state borders with degrading ecosystems, declining resource availability and increasing transportation costs. The maintenance of strong borders as selective filtration systems (goods, capital and people) is based on a cost-benefit analysis in which the economic benefits accruing from long distance, globalized resource exploitation are weighed against policing and infrastructure costs. As costs rise above benefits, borders fragment, with a transition to local barriers and conflicts, and mobile peoples moving to resources. Third, trends in urbanization and development of megacities under economic and environmental stress. The pattern of rapid growth of megacities through inward migration, with displaced people occupying high-risk urban landscapes such as flood plains or steep slopes and existing on the margins of the formal economic system, switches to outmigration as precarious slum dwellers respond to human-induced natural disasters, crumbling infrastructure and economic decline. Inefficient foraging along outward migration pathways from the urban center drives positive feedbacks that propel a radiating pattern and eventually lead to dispersal. These anticipated patterns represent a fragmentation of economic and power concentrations and networks, and localization of the presently globalized coupled human-landscape system. Long-time-scale models illustrating the fragmentation process and prospects for model testing will be discussed. Supported by the Geomorphology and Land Use Dynamics Program of the US National Science Foundation.

Scaling biodiversity responses to hydrological regimes.

PubMed

Rolls, Robert J; Heino, Jani; Ryder, Darren S; Chessman, Bruce C; Growns, Ivor O; Thompson, Ross M; Gido, Keith B

2018-05-01

Of all ecosystems, freshwaters support the most dynamic and highly concentrated biodiversity on Earth. These attributes of freshwater biodiversity along with increasing demand for water mean that these systems serve as significant models to understand drivers of global biodiversity change. Freshwater biodiversity changes are often attributed to hydrological alteration by water-resource development and climate change owing to the role of the hydrological regime of rivers, wetlands and floodplains affecting patterns of biodiversity. However, a major gap remains in conceptualising how the hydrological regime determines patterns in biodiversity's multiple spatial components and facets (taxonomic, functional and phylogenetic). We synthesised primary evidence of freshwater biodiversity responses to natural hydrological regimes to determine how distinct ecohydrological mechanisms affect freshwater biodiversity at local, landscape and regional spatial scales. Hydrological connectivity influences local and landscape biodiversity, yet responses vary depending on spatial scale. Biodiversity at local scales is generally positively associated with increasing connectivity whereas landscape-scale biodiversity is greater with increasing fragmentation among locations. The effects of hydrological disturbance on freshwater biodiversity are variable at separate spatial scales and depend on disturbance frequency and history and organism characteristics. The role of hydrology in determining habitat for freshwater biodiversity also depends on spatial scaling. At local scales, persistence, stability and size of habitat each contribute to patterns of freshwater biodiversity yet the responses are variable across the organism groups that constitute overall freshwater biodiversity. We present a conceptual model to unite the effects of different ecohydrological mechanisms on freshwater biodiversity across spatial scales, and develop four principles for applying a multi-scaled understanding of freshwater biodiversity responses to hydrological regimes. The protection and restoration of freshwater biodiversity is both a fundamental justification and a central goal of environmental water allocation worldwide. Clearer integration of concepts of spatial scaling in the context of understanding impacts of hydrological regimes on biodiversity will increase uptake of evidence into environmental flow implementation, identify suitable biodiversity targets responsive to hydrological change or restoration, and identify and manage risks of environmental flows contributing to biodiversity decline. © 2017 Cambridge Philosophical Society.

Patterning of leaf vein networks by convergent auxin transport pathways.

PubMed

Sawchuk, Megan G; Edgar, Alexander; Scarpella, Enrico

2013-01-01

The formation of leaf vein patterns has fascinated biologists for centuries. Transport of the plant signal auxin has long been implicated in vein patterning, but molecular details have remained unclear. Varied evidence suggests a central role for the plasma-membrane (PM)-localized PIN-FORMED1 (PIN1) intercellular auxin transporter of Arabidopsis thaliana in auxin-transport-dependent vein patterning. However, in contrast to the severe vein-pattern defects induced by auxin transport inhibitors, pin1 mutant leaves have only mild vein-pattern defects. These defects have been interpreted as evidence of redundancy between PIN1 and the other four PM-localized PIN proteins in vein patterning, redundancy that underlies many developmental processes. By contrast, we show here that vein patterning in the Arabidopsis leaf is controlled by two distinct and convergent auxin-transport pathways: intercellular auxin transport mediated by PM-localized PIN1 and intracellular auxin transport mediated by the evolutionarily older, endoplasmic-reticulum-localized PIN6, PIN8, and PIN5. PIN6 and PIN8 are expressed, as PIN1 and PIN5, at sites of vein formation. pin6 synthetically enhances pin1 vein-pattern defects, and pin8 quantitatively enhances pin1pin6 vein-pattern defects. Function of PIN6 is necessary, redundantly with that of PIN8, and sufficient to control auxin response levels, PIN1 expression, and vein network formation; and the vein pattern defects induced by ectopic PIN6 expression are mimicked by ectopic PIN8 expression. Finally, vein patterning functions of PIN6 and PIN8 are antagonized by PIN5 function. Our data define a new level of control of vein patterning, one with repercussions on other patterning processes in the plant, and suggest a mechanism to select cell files specialized for vascular function that predates evolution of PM-localized PIN proteins.

Cross-diffusion-induced subharmonic spatial resonances in a predator-prey system

NASA Astrophysics Data System (ADS)

Gambino, G.; Lombardo, M. C.; Sammartino, M.

2018-01-01

In this paper we investigate the complex dynamics originated by a cross-diffusion-induced subharmonic destabilization of the fundamental subcritical Turing mode in a predator-prey reaction-diffusion system. The model we consider consists of a two-species Lotka-Volterra system with linear diffusion and a nonlinear cross-diffusion term in the predator equation. The taxis term in the search strategy of the predator is responsible for the onset of complex dynamics. In fact, our model does not exhibit any Hopf or wave instability, and on the basis of the linear analysis one should only expect stationary patterns; nevertheless, the presence of the nonlinear cross-diffusion term is able to induce a secondary instability: due to a subharmonic spatial resonance, the stationary primary branch bifurcates to an out-of-phase oscillating solution. Noticeably, the strong resonance between the harmonic and the subharmonic is able to generate the oscillating pattern albeit the subharmonic is below criticality. We show that, as the control parameter is varied, the oscillating solution (sub T mode) can undergo a sequence of secondary instabilities, generating a transition toward chaotic dynamics. Finally, we investigate the emergence of sub T -mode solutions on two-dimensional domains: when the fundamental mode describes a square pattern, subharmonic resonance originates oscillating square patterns. In the case of subcritical Turing hexagon solutions, the internal interactions with a subharmonic mode are able to generate the so-called "twinkling-eyes" pattern.

Posttraumatic stress and alcohol use among veterans: Amygdala and anterior cingulate activation to emotional cues.

PubMed

Simons, Raluca M; Simons, Jeffrey S; Olson, Dawne; Baugh, Lee; Magnotta, Vincent; Forster, Gina

2016-11-01

This fMRI study tested a model of combat trauma, posttraumatic stress symptoms (PTSS), alcohol use, and behavioral and neural responses to emotional cues in 100 OIF/OEF/OND veterans. Multilevel structural equation models were tested for left and right dorsal ACC (dACC), rostral ACC (rACC), and amygdala blood-oxygen- level dependent responses during the emotional counting Stroop test and masked faces task. In the Stroop task, combat exposure moderated the effect of combat stimuli resulting in hyperactivation in the rACC and dACC. Activation in the left amygdala also increased in response to combat stimuli, but effects did not vary as a function of combat severity. In the masked faces task, activation patterns did not vary as a function of stimulus. However, at the between-person level, amygdala activation during the masked faces task was inversely associated with PTSS. In respect to behavioral outcomes, higher PTSS were associated with a stronger Stroop effect, suggesting greater interference associated with combat words. Results are consistent with the premise that combat trauma results in hyperactivation in the ACC in response to combat stimuli, and, via its effect on PTSS, is associated with deficits in cognitive performance in the presence of combat stimuli. Across tasks, predeployment drinking was inversely associated with activation in the dACC but not the rACC or amygdala. Drinking may be a buffering factor, or negatively reinforcing in part because of its effects on normalizing brain response following trauma exposure. Alternatively, drinking may undermine adaptive functioning of the dACC when responding to traumatic stress cues. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Probabilistic Learning by Rodent Grid Cells

PubMed Central

Cheung, Allen

2016-01-01

Mounting evidence shows mammalian brains are probabilistic computers, but the specific cells involved remain elusive. Parallel research suggests that grid cells of the mammalian hippocampal formation are fundamental to spatial cognition but their diverse response properties still defy explanation. No plausible model exists which explains stable grids in darkness for twenty minutes or longer, despite being one of the first results ever published on grid cells. Similarly, no current explanation can tie together grid fragmentation and grid rescaling, which show very different forms of flexibility in grid responses when the environment is varied. Other properties such as attractor dynamics and grid anisotropy seem to be at odds with one another unless additional properties are assumed such as a varying velocity gain. Modelling efforts have largely ignored the breadth of response patterns, while also failing to account for the disastrous effects of sensory noise during spatial learning and recall, especially in darkness. Here, published electrophysiological evidence from a range of experiments are reinterpreted using a novel probabilistic learning model, which shows that grid cell responses are accurately predicted by a probabilistic learning process. Diverse response properties of probabilistic grid cells are statistically indistinguishable from rat grid cells across key manipulations. A simple coherent set of probabilistic computations explains stable grid fields in darkness, partial grid rescaling in resized arenas, low-dimensional attractor grid cell dynamics, and grid fragmentation in hairpin mazes. The same computations also reconcile oscillatory dynamics at the single cell level with attractor dynamics at the cell ensemble level. Additionally, a clear functional role for boundary cells is proposed for spatial learning. These findings provide a parsimonious and unified explanation of grid cell function, and implicate grid cells as an accessible neuronal population readout of a set of probabilistic spatial computations. PMID:27792723

Reciprocal neural response within lateral and ventral medial prefrontal cortex during hot and cold reasoning.

PubMed

Goel, Vinod; Dolan, Raymond J

2003-12-01

Logic is widely considered the basis of rationality. Logical choices, however, are often influenced by emotional responses, sometimes to our detriment, sometimes to our advantage. To understand the neural basis of emotionally neutral ("cold") and emotionally salient ("hot") reasoning we studied 19 volunteers using event-related fMRI, as they made logical judgments about arguments that varied in emotional saliency. Despite identical logical form and content categories across "hot" and "cold" reasoning conditions, lateral and ventral medial prefrontal cortex showed reciprocal response patterns as a function of emotional saliency of content. "Cold" reasoning trials resulted in enhanced activity in lateral/dorsal lateral prefrontal cortex (L/DLPFC) and suppression of activity in ventral medial prefrontal cortex (VMPFC). By contrast, "hot" reasoning trials resulted in enhanced activation in VMPFC and suppression of activation in L/DLPFC. This reciprocal engagement of L/DLPFC and VMPFC provides evidence for a dynamic neural system for reasoning, the configuration of which is strongly influenced by emotional saliency.

Inmate responses to prison-based drug treatment: a repeated measures analysis.

PubMed

Welsh, Wayne N

2010-06-01

Using a sample of 347 prison inmates and general linear modeling (GLM) repeated measures analyses, this paper examined during-treatment responses (e.g., changes in psychological and social functioning) to prison-based TC drug treatment. These effects have rarely been examined in previous studies, and never with a fully multivariate model accounting for within-subjects effects (changes over time), between-subjects effects (e.g., levels of risk and motivation), and within/between-subjects interactions (timexriskxmotivation). The results provide evidence of positive inmate change in response to prison TC treatment, but the patterns of results varied depending upon: (a) specific indicators of psychological and social functioning, motivation, and treatment process; (b) the time periods examined (1, 6, and 12 months during treatment); and (c) baseline levels of risk and motivation. Significant interactions between time and type of inmate suggest important new directions for research, theory, and practice in offender-based substance abuse treatment. Copyright (c) 2010 Elsevier Ireland Ltd. All rights reserved.

The Response of Simple Polymer Structures Under Dynamic Loading

NASA Astrophysics Data System (ADS)

Proud, William; Ellison, Kay; Yapp, Su; Cole, Cloe; Galimberti, Stefano; Institute of Shock Physics Team

2017-06-01

The dynamic response of polymeric materials has been widely studied with the effects of degree of crystallinity, strain rate, temperature and sample size being commonly reported. This study uses a simple PMMA structure, a right cylindrical sample, with structural features such as holes. The features are added an varied in a systematic fashion. Samples were dynamically loaded using a Split Hopkinson Pressure Bar up to failure. The resulting stress-strain curves are presented showing the change in sample response. The strain to failure is shown to increase initially with the presence of holes, while failure stress is relatively unaffected. The fracture patterns seen in the failed samples change, with tensile cracks, Hertzian cones, shear effects being dominant for different holes sizes and geometries. The sample were prepared by laser cutting and checked for residual stress before experiment. The data is used to validate predictive model predictions where material, structure and damage are included.. The Institute of Shock Physics acknowledges the support of Imperial College London and the Atomic Weapons Establishment.

Spatially oriented plasmonic ‘nanograter’ structures

PubMed Central

Liu, Zhe; Cui, Ajuan; Gong, Zhijie; Li, Hongqiang; Xia, Xiaoxiang; Shen, Tiehan H.; Li, Junjie; Yang, Haifang; Li, Wuxia; Gu, Changzhi

2016-01-01

One of the key motivations in producing 3D structures has always been the realization of metamaterials with effective constituent properties that can be tuned in all propagation directions at various frequencies. Here, we report the investigation of spatially oriented “Nanograter” structures with orientation-dependent responses over a wide spectrum by focused-ion-beam based patterning and folding of thin film nanostructures. Au nano units of different shapes, standing along specifically designated orientations, were fabricated. Experimental measurements and simulation results show that such structures offer an additional degree of freedom for adjusting optical properties with the angle of inclination, in additional to the size of the structures. The response frequency can be varied in a wide range (8 μm–14 μm) by the spatial orientation (0°–180°) of the structures, transforming the response from magnetic into electric coupling. This may open up prospects for the fabrication of 3D nanostructures as optical interconnects, focusing elements and logic elements, moving toward the realization of 3D optical circuits. PMID:27357610

Evidence for cue-independent spatial representation in the human auditory cortex during active listening.

PubMed

Higgins, Nathan C; McLaughlin, Susan A; Rinne, Teemu; Stecker, G Christopher

2017-09-05

Few auditory functions are as important or as universal as the capacity for auditory spatial awareness (e.g., sound localization). That ability relies on sensitivity to acoustical cues-particularly interaural time and level differences (ITD and ILD)-that correlate with sound-source locations. Under nonspatial listening conditions, cortical sensitivity to ITD and ILD takes the form of broad contralaterally dominated response functions. It is unknown, however, whether that sensitivity reflects representations of the specific physical cues or a higher-order representation of auditory space (i.e., integrated cue processing), nor is it known whether responses to spatial cues are modulated by active spatial listening. To investigate, sensitivity to parametrically varied ITD or ILD cues was measured using fMRI during spatial and nonspatial listening tasks. Task type varied across blocks where targets were presented in one of three dimensions: auditory location, pitch, or visual brightness. Task effects were localized primarily to lateral posterior superior temporal gyrus (pSTG) and modulated binaural-cue response functions differently in the two hemispheres. Active spatial listening (location tasks) enhanced both contralateral and ipsilateral responses in the right hemisphere but maintained or enhanced contralateral dominance in the left hemisphere. Two observations suggest integrated processing of ITD and ILD. First, overlapping regions in medial pSTG exhibited significant sensitivity to both cues. Second, successful classification of multivoxel patterns was observed for both cue types and-critically-for cross-cue classification. Together, these results suggest a higher-order representation of auditory space in the human auditory cortex that at least partly integrates the specific underlying cues.

Evidence for cue-independent spatial representation in the human auditory cortex during active listening

PubMed Central

McLaughlin, Susan A.; Rinne, Teemu; Stecker, G. Christopher

2017-01-01

Few auditory functions are as important or as universal as the capacity for auditory spatial awareness (e.g., sound localization). That ability relies on sensitivity to acoustical cues—particularly interaural time and level differences (ITD and ILD)—that correlate with sound-source locations. Under nonspatial listening conditions, cortical sensitivity to ITD and ILD takes the form of broad contralaterally dominated response functions. It is unknown, however, whether that sensitivity reflects representations of the specific physical cues or a higher-order representation of auditory space (i.e., integrated cue processing), nor is it known whether responses to spatial cues are modulated by active spatial listening. To investigate, sensitivity to parametrically varied ITD or ILD cues was measured using fMRI during spatial and nonspatial listening tasks. Task type varied across blocks where targets were presented in one of three dimensions: auditory location, pitch, or visual brightness. Task effects were localized primarily to lateral posterior superior temporal gyrus (pSTG) and modulated binaural-cue response functions differently in the two hemispheres. Active spatial listening (location tasks) enhanced both contralateral and ipsilateral responses in the right hemisphere but maintained or enhanced contralateral dominance in the left hemisphere. Two observations suggest integrated processing of ITD and ILD. First, overlapping regions in medial pSTG exhibited significant sensitivity to both cues. Second, successful classification of multivoxel patterns was observed for both cue types and—critically—for cross-cue classification. Together, these results suggest a higher-order representation of auditory space in the human auditory cortex that at least partly integrates the specific underlying cues. PMID:28827357

Electrical Brain Responses to an Auditory Illusion and the Impact of Musical Expertise

PubMed Central

Ioannou, Christos I.; Pereda, Ernesto; Lindsen, Job P.; Bhattacharya, Joydeep

2015-01-01

The presentation of two sinusoidal tones, one to each ear, with a slight frequency mismatch yields an auditory illusion of a beating frequency equal to the frequency difference between the two tones; this is known as binaural beat (BB). The effect of brief BB stimulation on scalp EEG is not conclusively demonstrated. Further, no studies have examined the impact of musical training associated with BB stimulation, yet musicians' brains are often associated with enhanced auditory processing. In this study, we analysed EEG brain responses from two groups, musicians and non-musicians, when stimulated by short presentation (1 min) of binaural beats with beat frequency varying from 1 Hz to 48 Hz. We focused our analysis on alpha and gamma band EEG signals, and they were analysed in terms of spectral power, and functional connectivity as measured by two phase synchrony based measures, phase locking value and phase lag index. Finally, these measures were used to characterize the degree of centrality, segregation and integration of the functional brain network. We found that beat frequencies belonging to alpha band produced the most significant steady-state responses across groups. Further, processing of low frequency (delta, theta, alpha) binaural beats had significant impact on cortical network patterns in the alpha band oscillations. Altogether these results provide a neurophysiological account of cortical responses to BB stimulation at varying frequencies, and demonstrate a modulation of cortico-cortical connectivity in musicians' brains, and further suggest a kind of neuronal entrainment of a linear and nonlinear relationship to the beating frequencies. PMID:26065708

Electrical Brain Responses to an Auditory Illusion and the Impact of Musical Expertise.

PubMed

Ioannou, Christos I; Pereda, Ernesto; Lindsen, Job P; Bhattacharya, Joydeep

2015-01-01

The presentation of two sinusoidal tones, one to each ear, with a slight frequency mismatch yields an auditory illusion of a beating frequency equal to the frequency difference between the two tones; this is known as binaural beat (BB). The effect of brief BB stimulation on scalp EEG is not conclusively demonstrated. Further, no studies have examined the impact of musical training associated with BB stimulation, yet musicians' brains are often associated with enhanced auditory processing. In this study, we analysed EEG brain responses from two groups, musicians and non-musicians, when stimulated by short presentation (1 min) of binaural beats with beat frequency varying from 1 Hz to 48 Hz. We focused our analysis on alpha and gamma band EEG signals, and they were analysed in terms of spectral power, and functional connectivity as measured by two phase synchrony based measures, phase locking value and phase lag index. Finally, these measures were used to characterize the degree of centrality, segregation and integration of the functional brain network. We found that beat frequencies belonging to alpha band produced the most significant steady-state responses across groups. Further, processing of low frequency (delta, theta, alpha) binaural beats had significant impact on cortical network patterns in the alpha band oscillations. Altogether these results provide a neurophysiological account of cortical responses to BB stimulation at varying frequencies, and demonstrate a modulation of cortico-cortical connectivity in musicians' brains, and further suggest a kind of neuronal entrainment of a linear and nonlinear relationship to the beating frequencies.

Deciphering the role of a coleopteran steering muscle via free flight stimulation.

PubMed

Sato, Hirotaka; Vo Doan, Tat Thang; Kolev, Svetoslav; Huynh, Ngoc Anh; Zhang, Chao; Massey, Travis L; van Kleef, Joshua; Ikeda, Kazuo; Abbeel, Pieter; Maharbiz, Michel M

2015-03-16

Testing hypotheses of neuromuscular function during locomotion ideally requires the ability to record cellular responses and to stimulate the cells being investigated to observe downstream behaviors [1]. The inability to stimulate in free flight has been a long-standing hurdle for insect flight studies. The miniaturization of computation and communication technologies has delivered ultra-small, radio-enabled neuromuscular recorders and stimulators for untethered insects [2-8]. Published stimulation targets include the areas in brain potentially responsible for pattern generation in locomotion [5], the nerve chord for abdominal flexion [9], antennal muscles [2, 10], and the flight muscles (or their excitatory junctions) [7, 11-13]. However, neither fine nor graded control of turning has been demonstrated in free flight, and responses to the stimulation vary widely [2, 5, 7, 9]. Technological limitations have precluded hypotheses of function validation requiring exogenous stimulation during flight. We investigated the role of a muscle involved in wing articulation during flight in a coleopteran. We set out to identify muscles whose stimulation produced a graded turning in free flight, a feat that would enable fine steering control not previously demonstrated. We anticipated that gradation might arise either as a function of the phase of muscle firing relative to the wing stroke (as in the classic fly b1 muscle [14, 15] or the dorsal longitudinal and ventral muscles of moth [16]), or due to regulated tonic control, in which phase-independent summation of twitch responses produces varying amounts of force delivered to the wing linkages [15, 17, 18]. Copyright © 2015 Elsevier Ltd. All rights reserved.

Modeling spatial patterns of limits to production of deposit-feeders and ectothermic predators in the northern Bering Sea

NASA Astrophysics Data System (ADS)

Lovvorn, James R.; Jacob, Ute; North, Christopher A.; Kolts, Jason M.; Grebmeier, Jacqueline M.; Cooper, Lee W.; Cui, Xuehua

2015-03-01

Network models can help generate testable predictions and more accurate projections of food web responses to environmental change. Such models depend on predator-prey interactions throughout the network. When a predator currently consumes all of its prey's production, the prey's biomass may change substantially with loss of the predator or invasion by others. Conversely, if production of deposit-feeding prey is limited by organic matter inputs, system response may be predictable from models of primary production. For sea floor communities of shallow Arctic seas, increased temperature could lead to invasion or loss of predators, while reduced sea ice or change in wind-driven currents could alter organic matter inputs. Based on field data and models for three different sectors of the northern Bering Sea, we found a number of cases where all of a prey's production was consumed but the taxa involved varied among sectors. These differences appeared not to result from numerical responses of predators to abundance of preferred prey. Rather, they appeared driven by stochastic variations in relative biomass among taxa, due largely to abiotic conditions that affect colonization and early post-larval survival. Oscillatory tendencies of top-down versus bottom-up interactions may augment these variations. Required inputs of settling microalgae exceeded existing estimates of annual primary production by 50%; thus, assessing limits to bottom-up control depends on better corrections of satellite estimates to account for production throughout the water column. Our results suggest that in this Arctic system, stochastic abiotic conditions outweigh deterministic species interactions in food web responses to a varying environment.

Symbiosis of sea anemones and hermit crabs: different resource utilization patterns in the Aegean Sea

NASA Astrophysics Data System (ADS)

Vafeiadou, Anna-Maria; Antoniadou, Chryssanthi; Chintiroglou, Chariton

2012-09-01

The small-scale distribution and resource utilization patterns of hermit crabs living in symbiosis with sea anemones were investigated in the Aegean Sea. Four hermit crab species, occupying shells of nine gastropod species, were found in symbiosis with the sea anemone Calliactis parasitica. Shell resource utilization patterns varied among hermit crabs, with Dardanus species utilizing a wide variety of shells. The size structure of hermit crab populations also affected shell resource utilization, with small-sized individuals inhabiting a larger variety of shells. Sea anemone utilization patterns varied both among hermit crab species and among residence shells, with larger crabs and shells hosting an increased abundance and biomass of C. parasitica. The examined biometric relationships suggested that small-sized crabs carry, proportionally to their weight, heavier shells and increased anemone biomass than larger ones. Exceptions to the above patterns are related either to local resource availability or to other environmental factors.

Mapping lightscapes: spatial patterning of artificial lighting in an urban landscape.

PubMed

Hale, James D; Davies, Gemma; Fairbrass, Alison J; Matthews, Thomas J; Rogers, Christopher D F; Sadler, Jon P

2013-01-01

Artificial lighting is strongly associated with urbanisation and is increasing in its extent, brightness and spectral range. Changes in urban lighting have both positive and negative effects on city performance, yet little is known about how its character and magnitude vary across the urban landscape. A major barrier to related research, planning and governance has been the lack of lighting data at the city extent, particularly at a fine spatial resolution. Our aims were therefore to capture such data using aerial night photography and to undertake a case study of urban lighting. We present the finest scale multi-spectral lighting dataset available for an entire city and explore how lighting metrics vary with built density and land-use. We found positive relationships between artificial lighting indicators and built density at coarse spatial scales, whilst at a local level lighting varied with land-use. Manufacturing and housing are the primary land-use zones responsible for the city's brightly lit areas, yet manufacturing sites are relatively rare within the city. Our data suggests that efforts to address light pollution should broaden their focus from residential street lighting to include security lighting within manufacturing areas.

Mapping Lightscapes: Spatial Patterning of Artificial Lighting in an Urban Landscape

PubMed Central

Hale, James D.; Davies, Gemma; Fairbrass, Alison J.; Matthews, Thomas J.; Rogers, Christopher D. F.; Sadler, Jon P.

2013-01-01

Artificial lighting is strongly associated with urbanisation and is increasing in its extent, brightness and spectral range. Changes in urban lighting have both positive and negative effects on city performance, yet little is known about how its character and magnitude vary across the urban landscape. A major barrier to related research, planning and governance has been the lack of lighting data at the city extent, particularly at a fine spatial resolution. Our aims were therefore to capture such data using aerial night photography and to undertake a case study of urban lighting. We present the finest scale multi-spectral lighting dataset available for an entire city and explore how lighting metrics vary with built density and land-use. We found positive relationships between artificial lighting indicators and built density at coarse spatial scales, whilst at a local level lighting varied with land-use. Manufacturing and housing are the primary land-use zones responsible for the city’s brightly lit areas, yet manufacturing sites are relatively rare within the city. Our data suggests that efforts to address light pollution should broaden their focus from residential street lighting to include security lighting within manufacturing areas. PMID:23671566

Multiple spring migration strategies in a population of Pacific Common Eiders

USGS Publications Warehouse

Petersen, M.R.

2009-01-01

Spring migration strategies vary within and among species. Examination of this variability extends our understanding of life histories and has implications for conservation. I used satellite transmitters to determine migration strategies and evaluate factors influencing the timing of spring migration of Pacific Common Eiders (Somateria mollissima v-nigrum) that nest along the western Beaufort Sea coast. Adult females were marked at nesting colonies in the summers of 2000, 2001, and 2003, and were followed throughout spring migration the following year. Each year approximately equal proportions of eiders used three distinct migration strategies varying in duration, staging locations (waters near the Chukotka Peninsula, Russia, and the Chukchi and Beaufort seas, Alaska), and arrival dates at the nesting areas. It is unlikely that differences in the timing of movements to stopover sites in the Chukchi and Beaufort seas were a result of responses to changes in weather, particularly wind direction. Ice distribution and melt/movement patterns vary substantially among staging areas and thus may affect risk of starvation and reproductive potential. Long-term (decadal) changes in climate may favor birds using one strategy during "warmer" and another during "colder" years. ?? 2009 by The Cooper Ornithological Society. All rights reserved.

Vertical visual features have a strong influence on cuttlefish camouflage.

PubMed

Ulmer, K M; Buresch, K C; Kossodo, M M; Mäthger, L M; Siemann, L A; Hanlon, R T

2013-04-01

Cuttlefish and other cephalopods use visual cues from their surroundings to adaptively change their body pattern for camouflage. Numerous previous experiments have demonstrated the influence of two-dimensional (2D) substrates (e.g., sand and gravel habitats) on camouflage, yet many marine habitats have varied three-dimensional (3D) structures among which cuttlefish camouflage from predators, including benthic predators that view cuttlefish horizontally against such 3D backgrounds. We conducted laboratory experiments, using Sepia officinalis, to test the relative influence of horizontal versus vertical visual cues on cuttlefish camouflage: 2D patterns on benthic substrates were tested versus 2D wall patterns and 3D objects with patterns. Specifically, we investigated the influence of (i) quantity and (ii) placement of high-contrast elements on a 3D object or a 2D wall, as well as (iii) the diameter and (iv) number of 3D objects with high-contrast elements on cuttlefish body pattern expression. Additionally, we tested the influence of high-contrast visual stimuli covering the entire 2D benthic substrate versus the entire 2D wall. In all experiments, visual cues presented in the vertical plane evoked the strongest body pattern response in cuttlefish. These experiments support field observations that, in some marine habitats, cuttlefish will respond to vertically oriented background features even when the preponderance of visual information in their field of view seems to be from the 2D surrounding substrate. Such choices highlight the selective decision-making that occurs in cephalopods with their adaptive camouflage capability.

Risk attitudes in a changing environment: An evolutionary model of the fourfold pattern of risk preferences.

PubMed

Mallpress, Dave E W; Fawcett, Tim W; Houston, Alasdair I; McNamara, John M

2015-04-01

A striking feature of human decision making is the fourfold pattern of risk attitudes, involving risk-averse behavior in situations of unlikely losses and likely gains, but risk-seeking behavior in response to likely losses and unlikely gains. Current theories to explain this pattern assume particular psychological processes to reproduce empirical observations, but do not address whether it is adaptive for the decision maker to respond to risk in this way. Here, drawing on insights from behavioral ecology, we build an evolutionary model of risk-sensitive behavior, to investigate whether particular types of environmental conditions could favor a fourfold pattern of risk attitudes. We consider an individual foraging in a changing environment, where energy is needed to prevent starvation and build up reserves for reproduction. The outcome, in terms of reproductive value (a rigorous measure of evolutionary success), of a one-off choice between a risky and a safe gain, or between a risky and a safe loss, determines the risk-sensitive behavior we should expect to see in this environment. Our results show that the fourfold pattern of risk attitudes may be adaptive in an environment in which conditions vary stochastically but are autocorrelated in time. In such an environment the current options provide information about the likely environmental conditions in the future, which affect the optimal pattern of risk sensitivity. Our model predicts that risk preferences should be both path dependent and affected by the decision maker's current state. (c) 2015 APA, all rights reserved).

Predictability of Seasonal Precipitation Intensities Associated with Tropical Cyclones and Disturbances in Indo-China Region

NASA Astrophysics Data System (ADS)

Revel, M.; Utsumi, N.; Yoshikawa, S.; Kanae, S.

2016-12-01

Summer Monsoon precipitation provide support for the livelihood of the people of Southeast Asia where the population density is very high. Monsoon precipitation shows high variation in seasonal and yearly time scales affecting daily life of the people in the regions such Indo-China peninsula where most of the countries depend on agricultural economy. Predictability of seasonal extreme events such as flooding and droughts by different climatic conditions will enhance the ability to mitigate the risk of natural disasters in Indo-China peninsula. In addition lower tropospheric (850hPa) wind flow pattern is very useful in understanding the seasonal variability of Southeastern Asian Summer Monsoon. Furthermore summer monsoon in the Indo-China peninsula is strongly influenced by the local wind-terrain-precipitation interaction. Recently a set of Monsoon Indices has been developed by several researches, Indo China Monsoon Indices (ICMIs) as a representation of lower tropospheric wind flow patterns around Southeast Asian. On the other hand different precipitation providing weather systems vary according to the global position and local weather system. Responses of ICMIs to different precipitation providing weather systems may vary in temporal and spatial scales. Hence the seasonal responses of differentiated precipitation with ICMIs in Indo-China peninsula are being investigated. Objective detection methods are been adopted in order to identify the locations of tropical cyclones (TCs), and westward propagating disturbances (WDs) using a Japanese 25-year ReAnalysis data and the Global Precipitation Climatology Project One-Degree Daily data is differentiated into TCs, and WDs related precipitation. TCs contribute highly over the east coast of Indo China peninsula where WDs contributed all over land area of Indo-China peninsula but more towards Bay of Bengal. Correlations and regressions suggest that the indices which is calculated using the wind patterns, situated west of Indo-China peninsula tend to increase the moisture production to precipitation which is produced by seasonal winds and local convections. The increment of indices in the east of the peninsula tends withdraw the moisture of TCs and WDs related precipitation in Indo-China peninsula, as those originate from east of the peninsula.

Choice with frequently changing food rates and food ratios.

PubMed

Baum, William M; Davison, Michael

2014-03-01

In studies of operant choice, when one schedule of a concurrent pair is varied while the other is held constant, the constancy of the constant schedule may exert discriminative control over performance. In our earlier experiments, schedules varied reciprocally across components within sessions, so that while food ratio varied food rate remained constant. In the present experiment, we held one variable-interval (VI) schedule constant while varying the concurrent VI schedule within sessions. We studied five conditions, each with a different constant left VI schedule. On the right key, seven different VI schedules were presented in seven different unsignaled components. We analyzed performances at several different time scales. At the longest time scale, across conditions, behavior ratios varied with food ratios as would be expected from the generalized matching law. At shorter time scales, effects due to holding the left VI constant became more and more apparent, the shorter the time scale. In choice relations across components, preference for the left key leveled off as the right key became leaner. Interfood choice approximated strict matching for the varied right key, whereas interfood choice hardly varied at all for the constant left key. At the shortest time scale, visit patterns differed for the left and right keys. Much evidence indicated the development of a fix-and-sample pattern. In sum, the procedural difference made a large difference to performance, except for choice at the longest time scale and the fix-and-sample pattern at the shortest time scale. © Society for the Experimental Analysis of Behavior.

Adaptive scene-based correction algorithm for removal of residual fixed pattern noise in microgrid image data

NASA Astrophysics Data System (ADS)

Ratliff, Bradley M.; LeMaster, Daniel A.

2012-06-01

Pixel-to-pixel response nonuniformity is a common problem that affects nearly all focal plane array sensors. This results in a frame-to-frame fixed pattern noise (FPN) that causes an overall degradation in collected data. FPN is often compensated for through the use of blackbody calibration procedures; however, FPN is a particularly challenging problem because the detector responsivities drift relative to one another in time, requiring that the sensor be recalibrated periodically. The calibration process is obstructive to sensor operation and is therefore only performed at discrete intervals in time. Thus, any drift that occurs between calibrations (along with error in the calibration sources themselves) causes varying levels of residual calibration error to be present in the data at all times. Polarimetric microgrid sensors are particularly sensitive to FPN due to the spatial differencing involved in estimating the Stokes vector images. While many techniques exist in the literature to estimate FPN for conventional video sensors, few have been proposed to address the problem in microgrid imaging sensors. Here we present a scene-based nonuniformity correction technique for microgrid sensors that is able to reduce residual fixed pattern noise while preserving radiometry under a wide range of conditions. The algorithm requires a low number of temporal data samples to estimate the spatial nonuniformity and is computationally efficient. We demonstrate the algorithm's performance using real data from the AFRL PIRATE and University of Arizona LWIR microgrid sensors.

Neural mechanisms of single corrective steps evoked in the standing rabbit

PubMed Central

Hsu, L.-J.; Zelenin, P. V.; Lyalka, V. F.; Vemula, M. G.; Orlovsky, G. N.; Deliagina, T. G.

2017-01-01

Single steps in different directions are often used for postural corrections. However, our knowledge about the neural mechanisms underlying their generation is scarce. This study was aimed to characterize the corrective steps generated in response to disturbances of the basic body configuration caused by forward, backward or outward displacement of the hindlimb, as well as to reveal location in the CNS of the corrective step generating mechanisms. Video recording of the motor response to translation of the supporting surface under the hindlimb along with contact forces and activity of back and limb muscles was performed in freely standing intact and in fixed postmammillary rabbits. In intact rabbits, displacement of the hindlimb in any direction caused a lateral trunk movement towards the contralateral hindlimb, and then a corrective step in the direction opposite to the initial displacement. The time difference between onsets of these two events varied considerably. The EMG pattern in the supporting hindlimb was similar for all directions of corrective steps. It caused the increase in the limb stiffness. EMG pattern in the stepping limb differed in steps with different directions. In postmammillary rabbits the corrective stepping movements, as well as EMG patterns in both stepping and standing hindlimbs were similar to those observed in intact rabbits. This study demonstrates that the corrective trunk and limb movements are generated by separate mechanisms activated by sensory signals from the deviated limb. The neuronal networks generating postural corrective steps reside in the brainstem, cerebellum, and spinal cord. PMID:28215990

Assessment of Vestibular Rehabilitation Therapy Training and Practice Patterns

PubMed Central

Bush, Matthew L.; Dougherty, William

2015-01-01

Objective Vestibular rehabilitation therapy (VRT) can benefit patients with a variety of balance and vestibular disorders. This expanding field requires knowledgeable and experienced therapists; however, the practice and experience of those providing this care may vary greatly. The purpose of this study was to analyze variations in training and practice patterns among practicing vestibular rehabilitation therapists. Study Design Case-controlled cohort study Setting Investigation of outpatient physical therapy and audiology practices that offer vestibular rehabilitation conducted by a tertiary academic referral center. Main Outcome Measure Questionnaire-based investigation of level of training in vestibular disorders and therapy, practice patterns of vestibular rehabilitation, and referral sources for VRT patients. Results We identified 27 subjects within the state of Kentucky who practice vestibular rehabilitation and the questionnaire response rate was 63%. Responses indicated that 53% of respondents had no training in VRT during their professional degree program. Attendance of a course requiring demonstration of competence and techniques was 24% of participants. The development of VRT certification was significantly more favored by those who attended such courses compared with those who did not (p=0.01). 50% of therapists have direct access to patients without physician referrals. Conclusions There is a wide range of educational background and training among those practicing VRT. This variability in experience may affect care provided within some communities. Certification is not necessary for the practice of VRT but the development of certification is favored among some therapists to improve standardization of practice of this important specialty. PMID:25700790

Assessment of Vestibular Rehabilitation Therapy Training and Practice Patterns.

PubMed

Bush, Matthew L; Dougherty, William

2015-08-01

Vestibular rehabilitation therapy (VRT) can benefit patients with a variety of balance and vestibular disorders. This expanding field requires knowledgeable and experienced therapists; however, the practice and experience of those providing this care may vary greatly. The purpose of this study was to analyze variations in training and practice patterns among practicing vestibular rehabilitation therapists. Case-controlled cohort study. Investigation of outpatient physical therapy and audiology practices that offer vestibular rehabilitation conducted by a tertiary academic referral center. Questionnaire-based investigation of level of training in vestibular disorders and therapy, practice patterns of vestibular rehabilitation, and referral sources for VRT patients. We identified 27 subjects within the state of Kentucky who practice vestibular rehabilitation and the questionnaire response rate was 63%. Responses indicated that 53% of respondents had no training in VRT during their professional degree program. Attendance of a course requiring demonstration of competence and techniques was 24% of participants. The development of VRT certification was significantly more favored by those who attended such courses compared with those who did not (p = 0.01). 50% of therapists have direct access to patients without physician referrals. There is a wide range of educational background and training among those practicing VRT. This variability in experience may affect care provided within some communities. Certification is not necessary for the practice of VRT but the development of certification is favored among some therapists to improve standardization of practice of this important specialty.

Response allocation to concurrent fixed-ratio reinforcement schedules with work requirements by adults with mental retardation and typical preschool children.

PubMed Central

Cuvo, A J; Lerch, L J; Leurquin, D A; Gaffaney, T J; Poppen, R L

1998-01-01

The present experiments examined the effect of work requirements in combination with reinforcement schedule on the choice behavior of adults with mental retardation and preschool children. The work requirements of age-appropriate tasks (i.e., sorting silverware, jumping hurdles, tossing beanbags) were manipulated. Participants were presented with their choice of two response options for each trial that varied simultaneously on both work requirement and reinforcement schedule. Results showed that when responding to both choices occurred on the same reinforcement schedule, participants allocated most of their responses to the option with the easier work requirement. When the response option requiring less work was on a leaner reinforcement schedule, most participants shifted their choice to exert more work. There were individual differences across participants regarding their pattern of responding and when they switched from the lesser to the greater work requirement. Data showed that participants' responding was largely controlled by the reinforcement received for responding to each level of work. Various conceptualizations regarding the effects of work requirements on choice behavior are discussed. PMID:9532750

Body mass is positively associated with neural response to sweet taste, but not alcohol, among drinkers.

PubMed

Gardiner, Casey K; YorkWilliams, Sophie L; Bryan, Angela D; Hutchison, Kent E

2017-07-28

Obesity is a large and growing public health concern, presenting enormous economic and health costs to individuals and society. A burgeoning literature demonstrates that overweight and obese individuals display different neural processing of rewarding stimuli, including caloric substances, as compared to healthy weight individuals. However, much extant research on the neurobiology of obesity has focused on addiction models, without highlighting potentially separable neural underpinnings of caloric intake versus substance use. The present research explores these differences by examining neural response to alcoholic beverages and a sweet non-alcoholic beverage, among a sample of individuals with varying weight status and patterns of alcohol use and misuse. Participants received tastes of a sweet beverage (litchi juice) and alcoholic beverages during fMRI scanning. When controlling for alcohol use, elevated weight status was associated with increased activation in response to sweet taste in regions including the cingulate cortex, hippocampus, precuneus, and fusiform gyrus. However, weight status was not associated with neural response to alcoholic beverages. Copyright © 2017 Elsevier B.V. All rights reserved.

Mitochondrial adaptations to physiological vs. pathological cardiac hypertrophy

PubMed Central

Abel, E. Dale; Doenst, Torsten

2011-01-01

Cardiac hypertrophy is a stereotypic response of the heart to increased workload. The nature of the workload increase may vary depending on the stimulus (repetitive, chronic, pressure, or volume overload). If the heart fully adapts to the new loading condition, the hypertrophic response is considered physiological. If the hypertrophic response is associated with the ultimate development of contractile dysfunction and heart failure, the response is considered pathological. Although divergent signalling mechanisms may lead to these distinct patterns of hypertrophy, there is some overlap. Given the close relationship between workload and energy demand, any form of cardiac hypertrophy will impact the energy generation by mitochondria, which are the key organelles for cellular ATP production. Significant changes in the expression of nuclear and mitochondrially encoded transcripts that impact mitochondrial function as well as altered mitochondrial proteome composition and mitochondrial energetics have been described in various forms of cardiac hypertrophy. Here, we review mitochondrial alterations in pathological and physiological hypertrophy. We suggest that mitochondrial adaptations to pathological and physiological hypertrophy are distinct, and we shall review potential mechanisms that might account for these differences. PMID:21257612

To drink or grasp? How bullet ants ( Paraponera clavata) differentiate between sugars and proteins in liquids

NASA Astrophysics Data System (ADS)

Jandt, Jennifer; Larson, Hannah K.; Tellez, Peter; McGlynn, Terrence P.

2013-12-01

Flexibility in behavior can increase the likelihood that a forager may respond optimally in a fluctuating environment. Nevertheless, physiological or neuronal constraints may result in suboptimal responses to stimuli. We observed foraging workers of the giant tropical ant (also referred to as the "bullet ant"), Paraponera clavata, as they reacted to liquid solutions with varying concentrations of sugar and protein. We show that when protein/sucrose concentration is high, many bullet ants will often try to grasp at the droplet, rather than gather it by drinking. Because P. clavata actively hunt for prey, fixed action patterns and rapid responses to protein may be adaptively important, regardless of the medium in which it is presented. We conclude that, in P. clavata, food-handling decisions are made in response to the nutrient content of the food rather than the texture of the food. Further, we suggest that colonies that maintain a mixture of individuals with consistent fixed or flexible behavioral responses to food-handling decisions may be better adapted to fluctuating environmental conditions, and we propose future studies that could address this.

Seasonal patterns of predation for gray wolves in the multi-prey system of Yellowstone National Park.

PubMed

Metz, Matthew C; Smith, Douglas W; Vucetich, John A; Stahler, Daniel R; Peterson, Rolf O

2012-05-01

1. For large predators living in seasonal environments, patterns of predation are likely to vary among seasons because of related changes in prey vulnerability. Variation in prey vulnerability underlies the influence of predators on prey populations and the response of predators to seasonal variation in rates of biomass acquisition. Despite its importance, seasonal variation in predation is poorly understood. 2. We assessed seasonal variation in prey composition and kill rate for wolves Canis lupus living on the Northern Range (NR) of Yellowstone National Park. Our assessment was based on data collected over 14 winters (1995-2009) and five spring-summers between 2004 and 2009. 3. The species composition of wolf-killed prey and the age and sex composition of wolf-killed elk Cervus elaphus (the primary prey for NR wolves) varied among seasons. 4. One's understanding of predation depends critically on the metric used to quantify kill rate. For example, kill rate was greatest in summer when quantified as the number of ungulates acquired per wolf per day, and least during summer when kill rate was quantified as the biomass acquired per wolf per day. This finding contradicts previous research that suggests that rates of biomass acquisition for large terrestrial carnivores tend not to vary among seasons. 5. Kill rates were not well correlated among seasons. For example, knowing that early-winter kill rate is higher than average (compared with other early winters) provides little basis for anticipating whether kill rates a few months later during late winter will be higher or lower than average (compared with other late winters). This observation indicates how observing, for example, higher-than-average kill rates throughout any particular season is an unreliable basis for inferring that the year-round average kill rate would be higher than average. 6. Our work shows how a large carnivore living in a seasonal environment displays marked seasonal variation in predation because of changes in prey vulnerability. Patterns of wolf predation were influenced by the nutritional condition of adult elk and the availability of smaller prey (i.e. elk calves, deer). We discuss how these patterns affect our overall understanding of predator and prey population dynamics. © 2012 The Authors. Journal of Animal Ecology © 2012 British Ecological Society.

A general framework for predicting delayed responses of ecological communities to habitat loss.

PubMed

Chen, Youhua; Shen, Tsung-Jen

2017-04-20

Although biodiversity crisis at different spatial scales has been well recognised, the phenomena of extinction debt and immigration credit at a crossing-scale context are, at best, unclear. Based on two community patterns, regional species abundance distribution (SAD) and spatial abundance distribution (SAAD), Kitzes and Harte (2015) presented a macroecological framework for predicting post-disturbance delayed extinction patterns in the entire ecological community. In this study, we further expand this basic framework to predict diverse time-lagged effects of habitat destruction on local communities. Specifically, our generalisation of KH's model could address the questions that could not be answered previously: (1) How many species are subjected to delayed extinction in a local community when habitat is destructed in other areas? (2) How do rare or endemic species contribute to extinction debt or immigration credit of the local community? (3) How will species differ between two local areas? From the demonstrations using two SAD models (single-parameter lognormal and logseries), the predicted patterns of the debt, credit, and change in the fraction of unique species can vary, but with consistencies and depending on several factors. The general framework deepens the understanding of the theoretical effects of habitat loss on community dynamic patterns in local samples.

Detection biases yield misleading patterns of species persistence and colonization in fragmented landscapes

USGS Publications Warehouse

Ruiz-Gutierrez, Viviana; Zipkin, Elise F.

2011-01-01

Species occurrence patterns, and related processes of persistence, colonization and turnover, are increasingly being used to infer habitat suitability, predict species distributions, and measure biodiversity potential. The majority of these studies do not account for observational error in their analyses despite growing evidence suggesting that the sampling process can significantly influence species detection and subsequently, estimates of occurrence. We examined the potential biases of species occurrence patterns that can result from differences in detectability across species and habitat types using hierarchical multispecies occupancy models applied to a tropical bird community in an agricultural fragmented landscape. Our results suggest that detection varies widely among species and habitat types. Not incorporating detectability severely biased occupancy dynamics for many species by overestimating turnover rates, producing misleading patterns of persistence and colonization of agricultural habitats, and misclassifying species into ecological categories (i.e., forest specialists and generalists). This is of serious concern, given that most research on the ability of agricultural lands to maintain current levels of biodiversity by and large does not correct for differences in detectability. We strongly urge researchers to apply an inferential framework which explicitly account for differences in detectability to fully characterize species-habitat relationships, correctly guide biodiversity conservation in human-modified landscapes, and generate more accurate predictions of species responses to future changes in environmental conditions.

Animal-to-animal variability in the phasing of the crustacean cardiac motor pattern: an experimental and computational analysis

PubMed Central

Williams, Alex H.; Kwiatkowski, Molly A.; Mortimer, Adam L.; Marder, Eve; Zeeman, Mary Lou

2013-01-01

The cardiac ganglion (CG) of Homarus americanus is a central pattern generator that consists of two oscillatory groups of neurons: “small cells” (SCs) and “large cells” (LCs). We have shown that SCs and LCs begin their bursts nearly simultaneously but end their bursts at variable phases. This variability contrasts with many other central pattern generator systems in which phase is well maintained. To determine both the consequences of this variability and how CG phasing is controlled, we modeled the CG as a pair of Morris-Lecar oscillators coupled by electrical and excitatory synapses and constructed a database of 15,000 simulated networks using random parameter sets. These simulations, like our experimental results, displayed variable phase relationships, with the bursts beginning together but ending at variable phases. The model suggests that the variable phasing of the pattern has important implications for the functional role of the excitatory synapses. In networks in which the two oscillators had similar duty cycles, the excitatory coupling functioned to increase cycle frequency. In networks with disparate duty cycles, it functioned to decrease network frequency. Overall, we suggest that the phasing of the CG may vary without compromising appropriate motor output and that this variability may critically determine how the network behaves in response to manipulations. PMID:23446690

Computer-based video digitizer analysis of surface extension in maize roots: kinetics of growth rate changes during gravitropism

NASA Technical Reports Server (NTRS)

Ishikawa, H.; Hasenstein, K. H.; Evans, M. L.

1991-01-01

We used a video digitizer system to measure surface extension and curvature in gravistimulated primary roots of maize (Zea mays L.). Downward curvature began about 25 +/- 7 min after gravistimulation and resulted from a combination of enhanced growth along the upper surface and reduced growth along the lower surface relative to growth in vertically oriented controls. The roots curved at a rate of 1.4 +/- 0.5 degrees min-1 but the pattern of curvature varied somewhat. In about 35% of the samples the roots curved steadily downward and the rate of curvature slowed as the root neared 90 degrees. A final angle of about 90 degrees was reached 110 +/- 35 min after the start of gravistimulation. In about 65% of the samples there was a period of backward curvature (partial reversal of curvature) during the response. In some cases (about 15% of those showing a period of reverse bending) this period of backward curvature occurred before the root reached 90 degrees. Following transient backward curvature, downward curvature resumed and the root approached a final angle of about 90 degrees. In about 65% of the roots showing a period of reverse curvature, the roots curved steadily past the vertical, reaching maximum curvature about 205 +/- 65 min after gravistimulation. The direction of curvature then reversed back toward the vertical. After one or two oscillations about the vertical the roots obtained a vertical orientation and the distribution of growth within the root tip became the same as that prior to gravistimulation. The period of transient backward curvature coincided with and was evidently caused by enhancement of growth along the concave and inhibition of growth along the convex side of the curve, a pattern opposite to that prevailing in the earlier stages of downward curvature. There were periods during the gravitropic response when the normally unimodal growth-rate distribution within the elongation zone became bimodal with two peaks of rapid elongation separated by a region of reduced elongation rate. This occurred at different times on the convex and concave sides of the graviresponding root. During the period of steady downward curvature the elongation zone along the convex side extended farther toward the tip than in the vertical control. During the period of reduced rate of curvature, the zone of elongation extended farther toward the tip along the concave side of the root. The data show that the gravitropic response pattern varies with time and involves changes in localized elongation rates as well as changes in the length and position of the elongation zone. Models of root gravitropic curvature based on simple unimodal inhibition of growth along the lower side cannot account for these complex growth patterns.

The Influence of Epoch Length on Physical Activity Patterns Varies by Child's Activity Level

ERIC Educational Resources Information Center

Nettlefold, Lindsay; Naylor, P. J.; Warburton, Darren E. R.; Bredin, Shannon S. D.; Race, Douglas; McKay, Heather A.

2016-01-01

Purpose: Patterns of physical activity (PA) and sedentary time, including volume of bouted activity, are important health indicators. However, the effect of accelerometer epoch length on measurement of these patterns and associations with health outcomes in children remain unknown. Method: We measured activity patterns in 308 children (52% girls,…

The Contribution of Io-Raised Tides to Europa's Diurnally-Varying Surface Stresses

NASA Technical Reports Server (NTRS)

Rhoden, Alyssa Rose; Hurford, Terry A,; Manga, Michael

2011-01-01

Europa's icy surface records a rich history of geologic activity, Several features appear to be tectonic in origin and may have formed in response to Europa's daily-varying tidal stress [I]. Strike-slip faults and arcuate features called cycloids have both been linked to the patterns of stress change caused by eccentricity and obliquity [2J[3]. In fact, as Europa's obliquity has not been directly measured, observed tectonic patterns arc currently the best indicators of a theoretically supported [4] non-negligible obliquity. The diurnal tidal stress due to eccentricity is calculated by subtracting the average (or static) tidal shape of Europa generated by Jupiter's gravitational field from the instantaneous shape, which varies as Europa moves through its eccentric orbit [5]. In other words, it is the change of shape away from average that generates tidal stress. One might expect tidal contributions from the other large moons of Jupiter to be negligible given their size and the height of the tides they raise on Europa versus Jupiter's mass and the height of the tide it raises on Europa, However, what matters for tidally-induced stress is not how large the lo-raised bulge is compared to the Jupiter-raised bulge but rather the differences bet\\Veen the instantaneous and static bulges in each case. For example, when Europa is at apocenter, Jupiter raises a tide 30m lower than its static tide. At the same time, 10 raises a tide about 0.5m higher than its static tide. Hence, the change in Io's tidal distortion is about 2% of the change in the Jovian distortion when Europa is at apocenter

Differential Responses to a Visual Self-Motion Signal in Human Medial Cortical Regions Revealed by Wide-View Stimulation

PubMed Central

Wada, Atsushi; Sakano, Yuichi; Ando, Hiroshi

2016-01-01

Vision is important for estimating self-motion, which is thought to involve optic-flow processing. Here, we investigated the fMRI response profiles in visual area V6, the precuneus motion area (PcM), and the cingulate sulcus visual area (CSv)—three medial brain regions recently shown to be sensitive to optic-flow. We used wide-view stereoscopic stimulation to induce robust self-motion processing. Stimuli included static, randomly moving, and coherently moving dots (simulating forward self-motion). We varied the stimulus size and the presence of stereoscopic information. A combination of univariate and multi-voxel pattern analyses (MVPA) revealed that fMRI responses in the three regions differed from each other. The univariate analysis identified optic-flow selectivity and an effect of stimulus size in V6, PcM, and CSv, among which only CSv showed a significantly lower response to random motion stimuli compared with static conditions. Furthermore, MVPA revealed an optic-flow specific multi-voxel pattern in the PcM and CSv, where the discrimination of coherent motion from both random motion and static conditions showed above-chance prediction accuracy, but that of random motion from static conditions did not. Additionally, while area V6 successfully classified different stimulus sizes regardless of motion pattern, this classification was only partial in PcM and was absent in CSv. This may reflect the known retinotopic representation in V6 and the absence of such clear visuospatial representation in CSv. We also found significant correlations between the strength of subjective self-motion and univariate activation in all examined regions except for primary visual cortex (V1). This neuro-perceptual correlation was significantly higher for V6, PcM, and CSv when compared with V1, and higher for CSv when compared with the visual motion area hMT+. Our convergent results suggest the significant involvement of CSv in self-motion processing, which may give rise to its percept. PMID:26973588

Activation of AMP-activated protein kinase in response to temperature elevation shows seasonal variation in the zebra mussel, Dreissena polymorpha.

PubMed

Jost, Jennifer A; Keshwani, Sarah S; Abou-Hanna, Jacob J

2015-04-01

Global climate change is affecting ectothermic species, and a variety of studies are needed on thermal tolerances, especially from cellular and physiological perspectives. This study utilized AMP-activated protein kinase (AMPK), a key regulator of cellular energy levels, to examine the effects of high water temperatures on zebra mussel (Dreissena polymorpha) physiology. During heating, AMPK activity increased as water temperature increased to a point, and maximum AMPK activity was detected at high, but sublethal, water temperatures. This pattern varied with season, suggesting that cellular mechanisms of seasonal thermal acclimatization affect basic metabolic processes during sublethal heat stress. There was a greater seasonal variation in the water temperature at which maximum AMPK activity was measured than in lethal water temperature. Furthermore, baseline AMPK activity varied significantly across seasons, most likely reflecting altered metabolic states during times of growth and reproduction. In addition, when summer-collected mussels were lab-acclimated to winter and spring water temperatures, patterns of heat stress mirrored those of field-collected animals. These data suggest that water temperature is the main driver of the seasonal variation in physiology. This study concluded that AMPK activity, which reflects changes in energy supply and demand during heat stress, can serve as a sensitive and early indicator of temperature stress in mussels. Copyright © 2014 Elsevier Inc. All rights reserved.

Evolution of columns, modules, and domains in the neocortex of primates.

PubMed

Kaas, Jon H

2012-06-26

The specialized regions of neocortex of mammals, called areas, have been divided into smaller functional units called minicolumns, columns, modules, and domains. Here we describe some of these functional subdivisions of areas in primates and suggest when they emerged in mammalian evolution. We distinguish several types of these smaller subdivisions. Minicolumns, vertical arrays of neurons that are more densely interconnected with each other than with laterally neighboring neurons, are present in all cortical areas. Classic columns are defined by a repeating pattern of two or more types of cortex distinguished by having different inputs and neurons with different response properties. Sensory stimuli that continuously vary along a stimulus dimension may activate groups of neurons that vary continuously in location, producing "columns" without specific boundaries. Other groups or columns of cortical neurons are separated by narrow septa of fibers that reflect discontinuities in the receptor sheet. Larger regions of posterior parietal cortex and frontal motor cortex are parts of networks devoted to producing different sequences of movements. We distinguish these larger functionally distinct regions as domains. Columns of several types have evolved independently a number of times. Some of the columns found in primates likely emerged with the first primates, whereas others likely were present in earlier ancestors. The sizes and shapes of columns seem to depend on the balance of neuron activation patterns and molecular signals during development.

Growth and development of thermoregulation in nestling San Miguel Island Song Sparrows

USGS Publications Warehouse

Sogge, Mark K.; Kern, Michael D.; Kern, Robert; van Riper, Charles

1991-01-01

Patterns of growth (reviewed by Ricklefs 1968, 1969; O'Connor 1984) and the development of endothermy (reviewed by Dawson and Hudson 1970, Dunn 1975, Hill and Beaver 1982) have been well-studied in altricial wild birds, especially passerines. But few studies compare grown and thermogenesis in separate populations of the same species. Results of such studies with emberizids varied among species. King and Hubbard (1981), for example, found that nestlings from subarctic, subalpine, and low-altitude montane populations of White-crowned Sparrows (Zonotrichia leucophrys gambelii) grew at similar rates. In contrast, Rogers (1985) reported that the growth rates of nestlings in different populations of Savannah Sparrows (Passerculus sandwichensis) varied in response to the different environmental constraints of the localities in which they were reared. Nice (1937) and Smith et al. (1982) documented patterns of nestling growth in mainland (Ohio) and insular (Mandarte Island, British Columbia, Canada) populations of Song Sparrows (Melospiza melodia), respectively, and found that they were similar to those reported for most other passerines by Ricklefs (1968, 1969) and O'Connor (1984). In 1985-1986, we had the opportunity to examine the growth of nestlings from a third race of Song Sparrows, M. m. micronyx, which is endemic to San Miguel Island near Santa Barbara, California. We also studied the development of endothermy in these young birds, a process not hitherto described for nestling Song Sparrows. We report both in this paper.

Spatial and Temporal Dynamics of Carbon Fluxes in Glacial Meltwater Streams, Antarctica

NASA Astrophysics Data System (ADS)

Torrens, C.; Lyons, W. B.; McKnight, D. M.; Welch, K. A.; Gooseff, M. N.

2017-12-01

In the McMurdo Dry Valleys [MDV], Antarctica, glacial meltwater streams are the primary biogeochemical connectors linking glaciers, soils and lakes. These streams control the supply of nutrients and carbon to their terminal lakes, yet little is known about the magnitude, timing or distribution of these fluxes. The McMurdo Long Term Ecological Research project [MCM LTER] has collected over 20 years of sample data on dissolved organic and inorganic carbon in Taylor Valley streamwater; this is the first spatial and temporal analysis of this data. MDV streams are characterized by strong diel pulses in streamflow, specific electrical conductance, and temperature. Unlike temperate stream systems, there is no terrestrial vegetation, lateral overland flow or deep groundwater connection in MDV streams. As a result, the organic carbon is autochthonous, originating from stream microbial mats. Inorganic carbon is primarily bicarbonate; its source is hyporheic zone weathering. The carbonate system is in atmospheric equilibrium, reflecting the wide and shallow stream channels. Preliminary data show that the DOC flux varies with streamflow and is greater on the rising limb of the diel flow pulse. This pattern is more distinct in longer streams. DIC data does not show the same pattern, although the response may be blurred by a lag in hyporheic response to flood pulses and the lack of time-series data for alkalinity. Stream flood pulse dynamics control carbon loading to MDV lakes. As the climate changes, so will the timing and magnitude of diel flood pulses. This is likely to increase carbon loading to the Dry Valley lakes, altering the ecosystem carbon balance. This study increases our understanding of past and current patterns of carbon fluxes from streams to lakes; understanding past patterns will improve predictions of future changes.

Histologic and cytologic bone marrow findings in dogs with suspected precursor-targeted immune-mediated anemia and associated phagocytosis of erythroid precursors.

PubMed

Lucidi, Cynthia de A; de Rezende, Christian L E; Jutkowitz, L Ari; Scott, Michael A

2017-09-01

Precursor-targeted immune-mediated anemia (PIMA) has been suspected in dogs with nonregenerative anemia and bone marrow findings varying from erythroid hyperplasia to pure red cell aplasia. Phagocytosis of erythroid precursors/rubriphagocytosis (RP) reported in some affected dogs suggests a destructive component to the pathogenesis of PIMA. The purpose of the study was to characterize laboratory and clinical findings in dogs with suspected PIMA and RP, with emphasis on cytologic and histologic bone marrow findings. Dogs with PIMA and RP were identified by review of paired bone marrow aspirate and core biopsy slides collected over a 4-year period. Samples were systematically assessed and characterized along with other pertinent laboratory data and clinical findings. Twenty-five dogs met criteria for PIMA and had RP that was relatively stage-selective. Erythropoiesis was expanded to the stage of erythroid precursors undergoing most prominent phagocytosis, yielding patterns characterized by a hypo-, normo-, or hypercellular erythroid lineage. A 4 th pattern involved severe collagen myelofibrosis, and there was a spectrum of mild to severe collagen myelofibrosis overall. Evidence of immune-mediated hemolysis was rare. Immunosuppressive therapy was associated with remission in 77% of dogs treated for at least the median response time of 2 months. Bone marrow patterns in dogs fulfilling criteria for PIMA were aligned with stage-selective phagocytosis of erythroid precursors and the development of collagen myelofibrosis, common in dogs with PIMA. Recognition of these patterns and detection of RP facilitates diagnosis of PIMA, and slow response to immunosuppressive therapy warrants further investigation into its pathogenesis. © 2017 American Society for Veterinary Clinical Pathology.

Heat exposure in cities: combining the dynamics of temperature and population

NASA Astrophysics Data System (ADS)

Hu, L.; Wilhelmi, O.; Uejio, C. K.

2017-12-01

Assessment of human exposure to extreme heat requires the distributions of temperature and population. However, both variables are dynamic, thus presenting many challenges in capturing temperature and population patterns spatially and over time in an urban context. This study aims to improve the understanding of spatiotemporal patterns of urban population exposure to heat, taking Chicago, USA as an example. We estimate the hourly, geographically variable, population distribution considering commute of workers and students in a regular weekday and analyze the diurnal air temperature patterns during different meteorological conditions from satellite observations. The results show a relatively larger temperature increase in less urbanized areas during extreme heat events (EHEs), resulting in a spatially homogeneous temperature distribution over Chicago Metropolitan area. A lake cooling effect is weaker during EHEs. Population dynamics due to daily commute determine higher population density in more urbanized areas during daytime. The city-wide analysis reveals that the exposure is more sensitive to the nighttime temperature increases, and EHEs enhance this sensitivity. The high exposure hotspots are identified at the northwest Chicago, Cicero and Oak Park areas, where the influence from Lake Michigan is weakened, while the spatial extent of high outdoor exposure areas varies diurnally. This study's findings have potential to better inform general heat mitigation strategies during hot summer months and facilitate emergency response during EHEs. Availability of remotely-sensed temperature observations as well as the workers and students commute-adjusted population data allows for the adoption of this study's methodology in other major metropolitan areas. A better understanding of space-time patterns of urban population's exposure to heat will further enable local decision makers to mitigate extreme heat health risks and develop more targeted heat preparedness and response strategies.

High-Resolution Graphene Films for Electrochemical Sensing via Inkjet Maskless Lithography.

PubMed

Hondred, John A; Stromberg, Loreen R; Mosher, Curtis L; Claussen, Jonathan C

2017-10-24

Solution-phase printing of nanomaterial-based graphene inks are rapidly gaining interest for fabrication of flexible electronics. However, scalable manufacturing techniques for high-resolution printed graphene circuits are still lacking. Here, we report a patterning technique [i.e., inkjet maskless lithography (IML)] to form high-resolution, flexible, graphene films (line widths down to 20 μm) that significantly exceed the current inkjet printing resolution of graphene (line widths ∼60 μm). IML uses an inkjet printed polymer lacquer as a sacrificial pattern, viscous spin-coated graphene, and a subsequent graphene lift-off to pattern films without the need for prefabricated stencils, templates, or cleanroom technology (e.g., photolithography). Laser annealing is employed to increase conductivity on thermally sensitive, flexible substrates [polyethylene terephthalate (PET)]. Laser annealing and subsequent platinum nanoparticle deposition substantially increases the electroactive nature of graphene as illustrated by electrochemical hydrogen peroxide (H 2 O 2 ) sensing [rapid response (5 s), broad linear sensing range (0.1-550 μm), high sensitivity (0.21 μM/μA), and low detection limit (0.21 μM)]. Moreover, high-resolution, complex graphene circuits [i.e., interdigitated electrodes (IDE) with varying finger width and spacing] were created with IML and characterized via potassium chloride (KCl) electrochemical impedance spectroscopy (EIS). Results indicated that sensitivity directly correlates to electrode feature size as the IDE with the smallest finger width and spacing (50 and 50 μm) displayed the largest response to changes in KCl concentration (∼21 kΩ). These results indicate that the developed IML patterning technique is well-suited for rapid, solution-phase graphene film prototyping on flexible substrates for numerous applications including electrochemical sensing.

Climate adaption and post-fire restoration of a foundational perennial in cold desert: Insights from intraspecific variation in response to weather

USGS Publications Warehouse

Brabec, Martha M.; Germino, Matthew; Richardson, Bryce A.

2017-01-01

1.The loss of foundational but fire-intolerant perennials such as sagebrush due to increases in fire size and frequency in semiarid regions has motivated efforts to restore them, often with mixed or even no success. Seeds of sagebrush Artemisia tridentata and related species must be moved considerable distances from seed source to planting sites, but such transfers have not been guided by an understanding of local climate adaptation. Initial seedling establishment and its response to weather are a key demographic bottleneck that likely varies among subspecies and populations of sagebrush. 2.We assessed differences in survival, growth, and physiological responses of sagebrush to weather among eleven seed sources that varied in subspecies, cytotype, and climates-of-origin over 18 months following outplanting. Diploid or polyploid populations of mountain, Wyoming, and basin big sagebrush (A.tridentata ssp. vaseyana, A.tridentata ssp. wyomingensis, and A.tridentata ssp. tridentata, respectively) were planted onto five burned sites that normally support A.t.wyomingensis with some A.t.tridentata. 3.A.t.wyomingensis had the most growth and survival, and tetraploid populations had greater survival and height than diploids. Seasonal timing of mortality varied among the subspecies/cytotypes and was more closely related to minimum temperatures than water deficit. 4.Temperatures required to induce ice formation were up to 6°C more negative in 4n-A.t.tridentata and A.t.wyomingensis than other subspecies/cytotypes, indicating greater freezing avoidance. In contrast, freezing resistance of photosynthesis varied only 1°C among subspecies/cytotypes, being greatest in A.t.wyomingensis and least in the subspecies normally considered most cold-adapted,A.t.vaseyana. A large spectrum of reliance on freezing-avoidance vs. freezing-tolerance was observed and corresponded to differences in post-fire survivorship among subspecies/cytotypes. Differences in water deficit responses among subspecies/cytotypes were not as strong and did not relate to survival patterns. 5.Synthesis and applications. Low temperature responses are a key axis defining climate adaptation in young sagebrush seedlings and vary more with cytotype than with subspecies, which contrasts with the traditional emphases on (i) water limitations to explain establishment in these deserts, and (ii) subspecies in selecting restoration seedings. These important and novel insights on climate adaptation are critical for seed selection and parameterizing seed transfer zones, and were made possible by incorporating weather data with survival statistics. The survival/weather statistics used here could be applied to any restoration planting or seeding to help elucidate factors contributing to success and enable adaptive management.

Macroecological patterns of sexual size dimorphism in turtles of the world

USGS Publications Warehouse

Agha, Mickey; Ennen, Joshua R.; Nowakowski, A. Justin; Lovich, Jeffrey E.; Sweat, Sarah C.; Todd, Brian D.

2018-01-01

Sexual size dimorphism (SSD) is a well-documented phenomenon in both plants and animals; however, the ecological and evolutionary mechanisms that drive and maintain SSD patterns across geographic space at regional and global scales are understudied, especially for reptiles. Our goal was to examine geographic variation of turtle SSD and to explore ecological and environmental correlates using phylogenetic comparative methods. We use published body size data on 135 species from nine turtle families to examine how geographic patterns and the evolution of SSD are influenced by habitat specialization, climate (annual mean temperature and annual precipitation) and climate variability, latitude, or a combination of these predictor variables. We found that geographic variation, magnitude and direction of turtle SSD are best explained by habitat association, annual temperature variance and annual precipitation. Use of semi-aquatic and terrestrial habitats was associated with male-biased SSD, whereas use of aquatic habitat was associated with female-biased SSD. Our results also suggest that greater temperature variability is associated with female-biased SSD. In contrast, wetter climates are associated with male-biased SSD compared with arid climates that are associated with female-biased SSD. We also show support for a global latitudinal trend in SSD, with females being larger than males towards the poles, especially in the families Emydidae and Geoemydidae. Estimates of phylogenetic signal for both SSD and habitat type indicate that closely related species occupy similar habitats and exhibit similar direction and magnitude of SSD. These global patterns of SSD may arise from sex-specific reproductive behaviour, fecundity and sex-specific responses to environmental factors that differ among habitats and vary systematically across latitude. Thus, this study adds to our current understanding that while SSD can vary dramatically across and within turtle species under phylogenetic constraints, it may be driven, maintained and exaggerated by habitat type, climate and geographic location.

MODELING SCALE-DEPENDENT LANDSCAPE PATTERN, DISPERSAL, AND CONNECTIVITY FROM THE PERSPECTIVE OF THE ORGANISM

EPA Science Inventory

Effects of fine- to broad-scale patterns of landscape heterogeneity on dispersal success were examined for organisms varying in life history traits. To systematically control spatial pattern, a landscape model was created by merging physiographically-based maps of simulated land...

Visual detection following retinal damage: predictions of an inhomogeneous retino-cortical model

NASA Astrophysics Data System (ADS)

Arnow, Thomas L.; Geisler, Wilson S.

1996-04-01

A model of human visual detection performance has been developed, based on available anatomical and physiological data for the primate visual system. The inhomogeneous retino- cortical (IRC) model computes detection thresholds by comparing simulated neural responses to target patterns with responses to a uniform background of the same luminance. The model incorporates human ganglion cell sampling distributions; macaque monkey ganglion cell receptive field properties; macaque cortical cell contrast nonlinearities; and a optical decision rule based on ideal observer theory. Spatial receptive field properties of cortical neurons were not included. Two parameters were allowed to vary while minimizing the squared error between predicted and observed thresholds. One parameter was decision efficiency, the other was the relative strength of the ganglion-cell center and surround. The latter was only allowed to vary within a small range consistent with known physiology. Contrast sensitivity was measured for sinewave gratings as a function of spatial frequency, target size and eccentricity. Contrast sensitivity was also measured for an airplane target as a function of target size, with and without artificial scotomas. The results of these experiments, as well as contrast sensitivity data from the literature were compared to predictions of the IRC model. Predictions were reasonably good for grating and airplane targets.