Dissociation and Convergence of the Dorsal and Ventral Visual Streams in the Human Prefrontal Cortex

PubMed Central

Takahashi, Emi; Ohki, Kenichi; Kim, Dae-Shik

2012-01-01

Visual information is largely processed through two pathways in the primate brain: an object pathway from the primary visual cortex to the temporal cortex (ventral stream) and a spatial pathway to the parietal cortex (dorsal stream). Whether and to what extent dissociation exists in the human prefrontal cortex (PFC) has long been debated. We examined anatomical connections from functionally defined areas in the temporal and parietal cortices to the PFC, using noninvasive functional and diffusion-weighted magnetic resonance imaging. The right inferior frontal gyrus (IFG) received converging input from both streams, while the right superior frontal gyrus received input only from the dorsal stream. Interstream functional connectivity to the IFG was dynamically recruited only when both object and spatial information were processed. These results suggest that the human PFC receives dissociated and converging visual pathways, and that the right IFG region serves as an integrator of the two types of information. PMID:23063444

Sensation-to-Cognition Cortical Streams in Attention-Deficit/Hyperactivity Disorder

PubMed Central

Carmona, Susana; Hoekzema, Elseline; Castellanos, Francisco X.; García-García, David; Lage-Castellanos, Agustín; Dijk, Koene R.A.Van; Navas-Sánchez, Francisco J.; Martínez, Kenia; Desco, Manuel; Sepulcre, Jorge

2015-01-01

We sought to determine whether functional connectivity streams that link sensory, attentional, and higher-order cognitive circuits are atypical in attention-deficit/hyperactivity disorder (ADHD). We applied a graph-theory method to the resting-state functional magnetic resonance imaging data of 120 children with ADHD and 120 age-matched typically developing children (TDC). Starting in unimodal primary cortex—visual, auditory, and somatosensory—we used stepwise functional connectivity to calculate functional connectivity paths at discrete numbers of relay stations (or link-step distances). First, we characterized the functional connectivity streams that link sensory, attentional, and higher-order cognitive circuits in TDC and found that systems do not reach the level of integration achieved by adults. Second, we searched for stepwise functional connectivity differences between children with ADHD and TDC. We found that, at the initial steps of sensory functional connectivity streams, patients display significant enhancements of connectivity degree within neighboring areas of primary cortex, while connectivity to attention-regulatory areas is reduced. Third, at subsequent link-step distances from primary sensory cortex, children with ADHD show decreased connectivity to executive processing areas and increased degree of connections to default mode regions. Fourth, in examining medication histories in children with ADHD, we found that children medicated with psychostimulants present functional connectivity streams with higher degree of connectivity to regions subserving attentional and executive processes compared to medication-naïve children. We conclude that predominance of local sensory processing and lesser influx of information to attentional and executive regions may reduce the ability to organize and control the balance between external and internal sources of information in ADHD. PMID:25821110

Quantifying spatial differences in metabolism in headwater streams

Treesearch

Ricardo González-Pinzón; Roy Haggerty; Alba Argerich

2014-01-01

Stream functioning includes simultaneous interaction among solute transport, nutrient processing, and metabolism. Metabolism is measured with methods that have limited spatial representativeness and are highly uncertain. These problems restrict development of methods for up-scaling biological processes that mediate nutrient processing. We used the resazurin–resorufin (...

COMPARTMENTAL MODEL OF NITRATE RETENTION IN STREAMS

EPA Science Inventory

A compartmental modeling approach is presented to route nitrate retention along a cascade of stream reach sections. A process transfer function is used for transient storage equations with first order reaction terms to represent nitrate uptake in the free stream, and denitrifica...

Sources, transformations, and hydrological processes that control stream nitrate and dissolved organic matter concentrations during snowmelt in an upland forest

Treesearch

Stephen D. Sebestyen; Elizabeth W. Boyer; James B. Shanley; Carol Kendall; Daniel H. Doctor; George R. Aiken; Nobuhito Ohte

2008-01-01

We explored catchment processes that control stream nutrient concentrations at an upland forest in northeastern Vermont, USA, where inputs of nitrogen via atmospheric deposition are among the highest in the nation and affect ecosystem functioning. We traced sources of water, nitrate, and dissolved organic matter (DOM) using stream water samples collected at high...

Stream-related preferences of inputs to the superior colliculus from areas of dorsal and ventral streams of mouse visual cortex.

PubMed

Wang, Quanxin; Burkhalter, Andreas

2013-01-23

Previous studies of intracortical connections in mouse visual cortex have revealed two subnetworks that resemble the dorsal and ventral streams in primates. Although calcium imaging studies have shown that many areas of the ventral stream have high spatial acuity whereas areas of the dorsal stream are highly sensitive for transient visual stimuli, there are some functional inconsistencies that challenge a simple grouping into "what/perception" and "where/action" streams known in primates. The superior colliculus (SC) is a major center for processing of multimodal sensory information and the motor control of orienting the eyes, head, and body. Visual processing is performed in superficial layers, whereas premotor activity is generated in deep layers of the SC. Because the SC is known to receive input from visual cortex, we asked whether the projections from 10 visual areas of the dorsal and ventral streams terminate in differential depth profiles within the SC. We found that inputs from primary visual cortex are by far the strongest. Projections from the ventral stream were substantially weaker, whereas the sparsest input originated from areas of the dorsal stream. Importantly, we found that ventral stream inputs terminated in superficial layers, whereas dorsal stream inputs tended to be patchy and either projected equally to superficial and deep layers or strongly preferred deep layers. The results suggest that the anatomically defined ventral and dorsal streams contain areas that belong to distinct functional systems, specialized for the processing of visual information and visually guided action, respectively.

Restoring “hot spots” of denitrification along hydrologic flow-paths

EPA Science Inventory

Objectives: What are the relationships among N, C, and hydrology in degraded streams? What level of biogeochemical function remains with respect to N transformation processes (i.e. denitrification)? What could the results tell us about effectively restoring streams to process ...

Ecoregions and stream morphology in eastern Oklahoma

USGS Publications Warehouse

Splinter, D.K.; Dauwalter, D.C.; Marston, R.A.; Fisher, W.L.

2010-01-01

Broad-scale variables (i.e., geology, topography, climate, land use, vegetation, and soils) influence channel morphology. How and to what extent the longitudinal pattern of channel morphology is influenced by broad-scale variables is important to fluvial geomorphologists and stream ecologists. In the last couple of decades, there has been an increase in the amount of interdisciplinary research between fluvial geomorphologists and stream ecologists. In a historical context, fluvial geomorphologists are more apt to use physiographic regions to distinguish broad-scale variables, while stream ecologists are more apt to use the concept of an ecosystem to address the broad-scale variables that influence stream habitat. For this reason, we designed a study using ecoregions, which uses physical and biological variables to understand how landscapes influence channel processes. Ecoregions are delineated by similarities in geology, climate, soils, land use, and potential natural vegetation. In the fluvial system, stream form and function are dictated by processes observed throughout the fluvial hierarchy. Recognizing that stream form and function should differ by ecoregion, a study was designed to evaluate how the characteristics of stream channels differed longitudinally among three ecoregions in eastern Oklahoma, USA: Boston Mountains, Ozark Highlands, and Ouachita Mountains. Channel morphology of 149 stream reaches was surveyed in 1st- through 4th-order streams, and effects of drainage area and ecoregion on channel morphology was evaluated using multiple regressions. Differences existed (?????0.05) among ecoregions for particle size, bankfull width, and width/depth ratio. No differences existed among ecoregions for gradient or sinuosity. Particle size was smallest in the Ozark Highlands and largest in the Ouachita Mountains. Bankfull width was larger in the Ozark Highlands than in the Boston Mountains and Ouachita Mountains in larger streams. Width/depth ratios of the Boston Mountains and Ozark Highlands were not statistically different. Significant differences existed, however, between the Boston Mountains and Ozark Highlands when compared individually to the Ouachita Mountains. We found that ecoregions afforded a good spatial structure that can help in understanding longitudinal trends in stream reach morphology surveyed at the reach scale. The hierarchy of the fluvial system begins within a broad, relatively homogenous setting that imparts control on processes that affect stream function. Ecoregions provide an adequate regional division to begin a large-scale geomorphic study of processes in stream channels. ?? 2010 Elsevier B.V.

Continuous-flow free acid monitoring method and system

DOEpatents

Strain, J.E.; Ross, H.H.

1980-01-11

A free acid monitoring method and apparatus is provided for continuously measuring the excess acid present in a process stream. The disclosed monitoring system and method is based on the relationship of the partial pressure ratio of water and acid in equilibrium with an acid solution at constant temperature. A portion of the process stream is pumped into and flows through the monitor under the influence of gravity and back to the process stream. A continuous flowing sample is vaporized at a constant temperature and the vapor is subsequently condensed. Conductivity measurements of the condensate produces a nonlinear response function from which the free acid molarity of the sample process stream is determined.

Continuous-flow free acid monitoring method and system

DOEpatents

Strain, James E.; Ross, Harley H.

1981-01-01

A free acid monitoring method and apparatus is provided for continuously measuring the excess acid present in a process stream. The disclosed monitoring system and method is based on the relationship of the partial pressure ratio of water and acid in equilibrium with an acid solution at constant temperature. A portion of the process stream is pumped into and flows through the monitor under the influence of gravity and back to the process stream. A continuous flowing sample is vaporized at a constant temperature and the vapor is subsequently condensed. Conductivity measurements of the condensate produces a nonlinear response function from which the free acid molarity of the sample process stream is determined.

Sensation-to-cognition cortical streams in attention-deficit/hyperactivity disorder.

PubMed

Carmona, Susana; Hoekzema, Elseline; Castellanos, Francisco X; García-García, David; Lage-Castellanos, Agustín; Van Dijk, Koene R A; Navas-Sánchez, Francisco J; Martínez, Kenia; Desco, Manuel; Sepulcre, Jorge

2015-07-01

We sought to determine whether functional connectivity streams that link sensory, attentional, and higher-order cognitive circuits are atypical in attention-deficit/hyperactivity disorder (ADHD). We applied a graph-theory method to the resting-state functional magnetic resonance imaging data of 120 children with ADHD and 120 age-matched typically developing children (TDC). Starting in unimodal primary cortex-visual, auditory, and somatosensory-we used stepwise functional connectivity to calculate functional connectivity paths at discrete numbers of relay stations (or link-step distances). First, we characterized the functional connectivity streams that link sensory, attentional, and higher-order cognitive circuits in TDC and found that systems do not reach the level of integration achieved by adults. Second, we searched for stepwise functional connectivity differences between children with ADHD and TDC. We found that, at the initial steps of sensory functional connectivity streams, patients display significant enhancements of connectivity degree within neighboring areas of primary cortex, while connectivity to attention-regulatory areas is reduced. Third, at subsequent link-step distances from primary sensory cortex, children with ADHD show decreased connectivity to executive processing areas and increased degree of connections to default mode regions. Fourth, in examining medication histories in children with ADHD, we found that children medicated with psychostimulants present functional connectivity streams with higher degree of connectivity to regions subserving attentional and executive processes compared to medication-naïve children. We conclude that predominance of local sensory processing and lesser influx of information to attentional and executive regions may reduce the ability to organize and control the balance between external and internal sources of information in ADHD. © 2015 Wiley Periodicals, Inc.

Neuronal basis of speech comprehension.

PubMed

Specht, Karsten

2014-01-01

Verbal communication does not rely only on the simple perception of auditory signals. It is rather a parallel and integrative processing of linguistic and non-linguistic information, involving temporal and frontal areas in particular. This review describes the inherent complexity of auditory speech comprehension from a functional-neuroanatomical perspective. The review is divided into two parts. In the first part, structural and functional asymmetry of language relevant structures will be discus. The second part of the review will discuss recent neuroimaging studies, which coherently demonstrate that speech comprehension processes rely on a hierarchical network involving the temporal, parietal, and frontal lobes. Further, the results support the dual-stream model for speech comprehension, with a dorsal stream for auditory-motor integration, and a ventral stream for extracting meaning but also the processing of sentences and narratives. Specific patterns of functional asymmetry between the left and right hemisphere can also be demonstrated. The review article concludes with a discussion on interactions between the dorsal and ventral streams, particularly the involvement of motor related areas in speech perception processes, and outlines some remaining unresolved issues. This article is part of a Special Issue entitled Human Auditory Neuroimaging. Copyright © 2013 Elsevier B.V. All rights reserved.

Testing the dual-pathway model for auditory processing in human cortex.

PubMed

Zündorf, Ida C; Lewald, Jörg; Karnath, Hans-Otto

2016-01-01

Analogous to the visual system, auditory information has been proposed to be processed in two largely segregated streams: an anteroventral ("what") pathway mainly subserving sound identification and a posterodorsal ("where") stream mainly subserving sound localization. Despite the popularity of this assumption, the degree of separation of spatial and non-spatial auditory information processing in cortex is still under discussion. In the present study, a statistical approach was implemented to investigate potential behavioral dissociations for spatial and non-spatial auditory processing in stroke patients, and voxel-wise lesion analyses were used to uncover their neural correlates. The results generally provided support for anatomically and functionally segregated auditory networks. However, some degree of anatomo-functional overlap between "what" and "where" aspects of processing was found in the superior pars opercularis of right inferior frontal gyrus (Brodmann area 44), suggesting the potential existence of a shared target area of both auditory streams in this region. Moreover, beyond the typically defined posterodorsal stream (i.e., posterior superior temporal gyrus, inferior parietal lobule, and superior frontal sulcus), occipital lesions were found to be associated with sound localization deficits. These results, indicating anatomically and functionally complex cortical networks for spatial and non-spatial auditory processing, are roughly consistent with the dual-pathway model of auditory processing in its original form, but argue for the need to refine and extend this widely accepted hypothesis. Copyright © 2015 Elsevier Inc. All rights reserved.

Geospatial Data Stream Processing in Python Using FOSS4G Components

NASA Astrophysics Data System (ADS)

McFerren, G.; van Zyl, T.

2016-06-01

One viewpoint of current and future IT systems holds that there is an increase in the scale and velocity at which data are acquired and analysed from heterogeneous, dynamic sources. In the earth observation and geoinformatics domains, this process is driven by the increase in number and types of devices that report location and the proliferation of assorted sensors, from satellite constellations to oceanic buoy arrays. Much of these data will be encountered as self-contained messages on data streams - continuous, infinite flows of data. Spatial analytics over data streams concerns the search for spatial and spatio-temporal relationships within and amongst data "on the move". In spatial databases, queries can assess a store of data to unpack spatial relationships; this is not the case on streams, where spatial relationships need to be established with the incomplete data available. Methods for spatially-based indexing, filtering, joining and transforming of streaming data need to be established and implemented in software components. This article describes the usage patterns and performance metrics of a number of well known FOSS4G Python software libraries within the data stream processing paradigm. In particular, we consider the RTree library for spatial indexing, the Shapely library for geometric processing and transformation and the PyProj library for projection and geodesic calculations over streams of geospatial data. We introduce a message oriented Python-based geospatial data streaming framework called Swordfish, which provides data stream processing primitives, functions, transports and a common data model for describing messages, based on the Open Geospatial Consortium Observations and Measurements (O&M) and Unidata Common Data Model (CDM) standards. We illustrate how the geospatial software components are integrated with the Swordfish framework. Furthermore, we describe the tight temporal constraints under which geospatial functionality can be invoked when processing high velocity, potentially infinite geospatial data streams. The article discusses the performance of these libraries under simulated streaming loads (size, complexity and volume of messages) and how they can be deployed and utilised with Swordfish under real load scenarios, illustrated by a set of Vessel Automatic Identification System (AIS) use cases. We conclude that the described software libraries are able to perform adequately under geospatial data stream processing scenarios - many real application use cases will be handled sufficiently by the software.

The ecology and biogeochemistry of stream biofilms.

PubMed

Battin, Tom J; Besemer, Katharina; Bengtsson, Mia M; Romani, Anna M; Packmann, Aaron I

2016-04-01

Streams and rivers form dense networks, shape the Earth's surface and, in their sediments, provide an immensely large surface area for microbial growth. Biofilms dominate microbial life in streams and rivers, drive crucial ecosystem processes and contribute substantially to global biogeochemical fluxes. In turn, water flow and related deliveries of nutrients and organic matter to biofilms constitute major constraints on microbial life. In this Review, we describe the ecology and biogeochemistry of stream biofilms and highlight the influence of physical and ecological processes on their structure and function. Recent advances in the study of biofilm ecology may pave the way towards a mechanistic understanding of the effects of climate and environmental change on stream biofilms and the biogeochemistry of stream ecosystems.

Quantitative measurement of stream respiration using the resazurin-resorufin system

NASA Astrophysics Data System (ADS)

Gonzalez Pinzon, R. A.; Acker, S.; Haggerty, R.; Myrold, D.

2011-12-01

After three decades of active research in hydrology and stream ecology, the relationship between stream solute transport, metabolism and nutrient dynamics is still unresolved. These knowledge gaps obscure the function of stream ecosystems and how they interact with other landscape processes. To date, measuring rates of stream metabolism is accomplished with techniques that have vast uncertainties and are not spatially representative. These limitations mask the role of metabolism in nutrient processing. Clearly, more robust techniques are needed to develop mechanistic relationships that will ultimately improve our fundamental understanding of in-stream processes and how streams interact with other ecosystems. We investigated the "metabolic window of detection" of the Resazurin (Raz)-Resorufin (Rru) system (Haggerty et al., 2008, 2009). Although previous results have shown that the transformation of Raz to Rru is strongly correlated with respiration, a quantitative relationship between them is needed. We investigated this relationship using batch experiments with pure cultures (aerobic and anaerobic) and flow-through columns with incubated sediments from four different streams. The results suggest that the Raz-Rru system is a suitable approach that will enable hydrologists and stream ecologists to measure in situ and in vivo respiration at different scales, thus opening a reliable alternative to investigate how solute transport and stream metabolism control nutrient processing.

Objects, Numbers, Fingers, Space: Clustering of Ventral and Dorsal Functions in Young Children and Adults

ERIC Educational Resources Information Center

Chinello, Alessandro; Cattani, Veronica; Bonfiglioli, Claudia; Dehaene, Stanislas; Piazza, Manuela

2013-01-01

In the primate brain, sensory information is processed along two partially segregated cortical streams: the ventral stream, mainly coding for objects' shape and identity, and the dorsal stream, mainly coding for objects' quantitative information (including size, number, and spatial position). Neurophysiological measures indicate that such…

Effects of invertebrates in lotic ecosystem processes

Treesearch

J.B. Wallace; J.J. Jr. Hutchens

2000-01-01

Freshwater invertebrates perform many roles in ecosystem processes (Palmer et al., 1997) and these roles are frequently associated with a diverse array of feeding habits which have been organized into functional feeding groups (FFGs). Wallace and Webster (1996) reviewed many roles ofFFGs in stream ecosystems. Streams differ markedly from most ecosystems in that the...

What puts the how in where? Tool use and the divided visual streams hypothesis.

PubMed

Frey, Scott H

2007-04-01

An influential theory suggests that the dorsal (occipito-parietal) visual stream computes representations of objects for purposes of guiding actions (determining 'how') independently of ventral (occipito-temporal) stream processes supporting object recognition and semantic processing (determining 'what'). Yet, the ability of the dorsal stream alone to account for one of the most common forms of human action, tool use, is limited. While experience-dependent modifications to existing dorsal stream representations may explain simple tool use behaviors (e.g., using sticks to extend reach) found among a variety of species, skillful use of manipulable artifacts (e.g., cups, hammers, pencils) requires in addition access to semantic representations of objects' functions and uses. Functional neuroimaging suggests that this latter information is represented in a left-lateralized network of temporal, frontal and parietal areas. I submit that the well-established dominance of the human left hemisphere in the representation of familiar skills stems from the ability for this acquired knowledge to influence the organization of actions within the dorsal pathway.

Organization of the Macaque Extrastriate Visual Cortex Re-Examined Using the Principle of Spatial Continuity of Function

PubMed Central

Aflalo, T. N.

2011-01-01

How is the macaque monkey extrastriate cortex organized? Is vision divisible into separate tasks, such as object recognition and spatial processing, each emphasized in a different anatomical stream? If so, how many streams exist? What are the hierarchical relationships among areas? The present study approached the organization of the extrastriate cortex in a novel manner. A principled relationship exists between cortical function and cortical topography. Similar functions tend to be located near each other, within the constraints of mapping a highly dimensional space of functions onto the two-dimensional space of the cortex. We used this principle to re-examine the functional organization of the extrastriate cortex given current knowledge about its topographic organization. The goal of the study was to obtain a model of the functional relationships among the visual areas, including the number of functional streams into which they are grouped, the pattern of informational overlap among the streams, and the hierarchical relationships among areas. To test each functional description, we mapped it to a model cortex according to the principle of optimal continuity and assessed whether it accurately reconstructed a version of the extrastriate topography. Of the models tested, the one that best reconstructed the topography included four functional streams rather than two, six levels of hierarchy per stream, and a specific pattern of informational overlap among streams and areas. A specific mixture of functions was predicted for each visual area. This description matched findings in the physiological literature, and provided predictions of functional relationships that have yet to be tested physiologically. PMID:21068269

'What' and 'where' in the human brain.

PubMed

Ungerleider, L G; Haxby, J V

1994-04-01

Multiple visual areas in the cortex of nonhuman primates are organized into two hierarchically organized and functionally specialized processing pathways, a 'ventral stream' for object vision and a 'dorsal stream' for spatial vision. Recent findings from positron emission tomography activation studies have localized these pathways within the human brain, yielding insights into cortical hierarchies, specialization of function, and attentional mechanisms.

An Expanded Role for the Dorsal Auditory Pathway in Sensorimotor Control and Integration

PubMed Central

Rauschecker, Josef P.

2010-01-01

The dual-pathway model of auditory cortical processing assumes that two largely segregated processing streams originating in the lateral belt subserve the two main functions of hearing: identification of auditory “objects”, including speech; and localization of sounds in space (Rauschecker and Tian, 2000). Evidence has accumulated, chiefly from work in humans and nonhuman primates, that an antero-ventral pathway supports the former function, whereas a postero-dorsal stream supports the latter, i.e. processing of space and motion-in-space. In addition, the postero-dorsal stream has also been postulated to subserve some functions of speech and language in humans. A recent review (Rauschecker and Scott, 2009) has proposed the possibility that both functions of the postero-dorsal pathway can be subsumed under the same structural forward model: an efference copy sent from prefrontal and premotor cortex provides the basis for “optimal state estimation” in the inferior parietal lobe and in sensory areas of the posterior auditory cortex. The current article corroborates this model by adding and discussing recent evidence. PMID:20850511

Distribution of model uncertainty across multiple data streams

NASA Astrophysics Data System (ADS)

Wutzler, Thomas

2014-05-01

When confronting biogeochemical models with a diversity of observational data streams, we are faced with the problem of weighing the data streams. Without weighing or multiple blocked cost functions, model uncertainty is allocated to the sparse data streams and possible bias in processes that are strongly constraint is exported to processes that are constrained by sparse data streams only. In this study we propose an approach that aims at making model uncertainty a factor of observations uncertainty, that is constant over all data streams. Further we propose an implementation based on Monte-Carlo Markov chain sampling combined with simulated annealing that is able to determine this variance factor. The method is exemplified both with very simple models, artificial data and with an inversion of the DALEC ecosystem carbon model against multiple observations of Howland forest. We argue that the presented approach is able to help and maybe resolve the problem of bias export to sparse data streams.

Vulnerability of stream community composition and function to projected thermal warming and hydrologic change across ecoregions in the western United States.

PubMed

Pyne, Matthew I; Poff, N LeRoy

2017-01-01

Shifts in biodiversity and ecological processes in stream ecosystems in response to rapid climate change will depend on how numerically and functionally dominant aquatic insect species respond to changes in stream temperature and hydrology. Across 253 minimally perturbed streams in eight ecoregions in the western USA, we modeled the distribution of 88 individual insect taxa in relation to existing combinations of maximum summer temperature, mean annual streamflow, and their interaction. We used a heat map approach along with downscaled general circulation model (GCM) projections of warming and streamflow change to estimate site-specific extirpation likelihood for each taxon, allowing estimation of whole-community change in streams across these ecoregions. Conservative climate change projections indicate a 30-40% loss of taxa in warmer, drier ecoregions and 10-20% loss in cooler, wetter ecoregions where taxa are relatively buffered from projected warming and hydrologic change. Differential vulnerability of taxa with key functional foraging roles in processing basal resources suggests that climate change has the potential to modify stream trophic structure and function (e.g., alter rates of detrital decomposition and algal consumption), particularly in warmer and drier ecoregions. We show that streamflow change is equally as important as warming in projected risk to stream community composition and that the relative threat posed by these two fundamental drivers varies across ecoregions according to projected gradients of temperature and hydrologic change. Results also suggest that direct human modification of streams through actions such as water abstraction is likely to further exacerbate loss of taxa and ecosystem alteration, especially in drying climates. Management actions to mitigate climate change impacts on stream ecosystems or to proactively adapt to them will require regional calibration, due to geographic variation in insect sensitivity and in exposure to projected thermal warming and hydrologic change. © 2016 John Wiley & Sons Ltd.

Dynamic visualization of data streams

DOEpatents

Wong, Pak Chung [Richalnd, WA; Foote, Harlan P [Richland, WA; Adams, Daniel R [Kennewick, WA; Cowley, Wendy E [Richland, WA; Thomas, James J [Richland, WA

2009-07-07

One embodiment of the present invention includes a data communication subsystem to receive a data stream, and a data processing subsystem responsive to the data communication subsystem to generate a visualization output based on a group of data vectors corresponding to a first portion of the data stream. The processing subsystem is further responsive to a change in rate of receipt of the data to modify the visualization output with one or more other data vectors corresponding to a second portion of the data stream as a function of eigenspace defined with the group of data vectors. The system further includes a display device responsive to the visualization output to provide a corresponding visualization.

A method to assess longitudinal riverine connectivity in tropical streams dominated by migratory data

Treesearch

Kelly E. Crook; Catherine M. Pringle; Mary C. Freeman

2009-01-01

1. One way in which dams affect ecosystem function is by altering the distribution and abundance of aquatic species. 2. Previous studies indicate that migratory shrimps have significant effects on ecosystem processes in Puerto Rican streams, but are vulnerable to impediments to upstream or downstream passage, such as dams and associated water intakes where stream water...

Integration and segregation in auditory scene analysis

NASA Astrophysics Data System (ADS)

Sussman, Elyse S.

2005-03-01

Assessment of the neural correlates of auditory scene analysis, using an index of sound change detection that does not require the listener to attend to the sounds [a component of event-related brain potentials called the mismatch negativity (MMN)], has previously demonstrated that segregation processes can occur without attention focused on the sounds and that within-stream contextual factors influence how sound elements are integrated and represented in auditory memory. The current study investigated the relationship between the segregation and integration processes when they were called upon to function together. The pattern of MMN results showed that the integration of sound elements within a sound stream occurred after the segregation of sounds into independent streams and, further, that the individual streams were subject to contextual effects. These results are consistent with a view of auditory processing that suggests that the auditory scene is rapidly organized into distinct streams and the integration of sequential elements to perceptual units takes place on the already formed streams. This would allow for the flexibility required to identify changing within-stream sound patterns, needed to appreciate music or comprehend speech..

fMRI Evidence for Dorsal Stream Processing Abnormality in Adults Born Preterm

ERIC Educational Resources Information Center

Chaminade, Thierry; Leutcher, Russia Ha-Vinh; Millet, Veronique; Deruelle, Christine

2013-01-01

We investigated the consequences of premature birth on the functional neuroanatomy of the dorsal stream of visual processing. fMRI was recorded while sixteen healthy participants, 8 (two men) adults (19 years 6 months old, SD 10 months) born premature (mean gestational age 30 weeks), referred to as Premas, and 8 (two men) matched controls (20…

Thinking beyond the Bioreactor Box: Incorporating Stream Ecology into Edge-of-Field Nitrate Management.

PubMed

Goeller, Brandon C; Febria, Catherine M; Harding, Jon S; McIntosh, Angus R

2016-05-01

Around the world, artificially drained agricultural lands are significant sources of reactive nitrogen to stream ecosystems, creating substantial stream health problems. One management strategy is the deployment of denitrification enhancement tools. Here, we evaluate the factors affecting the potential of denitrifying bioreactors to improve stream health and ecosystem services. The performance of bioreactors and the structure and functioning of stream biotic communities are linked by environmental parameters like dissolved oxygen and nitrate-nitrogen concentrations, dissolved organic carbon availability, flow and temperature regimes, and fine sediment accumulations. However, evidence of bioreactors' ability to improve waterway health and ecosystem services is lacking. To improve the potential of bioreactors to enhance desirable stream ecosystem functioning, future assessments of field-scale bioreactors should evaluate the influences of bioreactor performance on ecological indicators such as primary production, organic matter processing, stream metabolism, and invertebrate and fish assemblage structure and function. These stream health impact assessments should be conducted at ecologically relevant spatial and temporal scales. Bioreactors have great potential to make significant contributions to improving water quality, stream health, and ecosystem services if they are tailored to site-specific conditions and implemented strategically with land-based and stream-based mitigation tools within watersheds. This will involve combining economic, logistical, and ecological information in their implementation. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Dynamic Object Representations in Infants with and without Fragile X Syndrome

PubMed Central

Farzin, Faraz; Rivera, Susan M.

2009-01-01

Our visual world is dynamic in nature. The ability to encode, mentally represent, and track an object's identity as it moves across time and space is critical for integrating and maintaining a complete and coherent view of the world. Here we investigated dynamic object processing in typically developing (TD) infants and infants with fragile X syndrome (FXS), a single-gene disorder associated with deficits in dorsal stream functioning. We used the violation of expectation method to assess infants’ visual response to expected versus unexpected outcomes following a brief dynamic (dorsal stream) or static (ventral stream) occlusion event. Consistent with previous reports of deficits in dorsal stream-mediated functioning in individuals with this disorder, these results reveal that, compared to mental age-matched TD infants, infants with FXS could maintain the identity of static, but not dynamic, object information during occlusion. These findings are the first to experimentally evaluate visual object processing skills in infants with FXS, and further support the hypothesis of dorsal stream difficulties in infants with this developmental disorder. PMID:20224809

Investigating category- and shape-selective neural processing in ventral and dorsal visual stream under interocular suppression.

PubMed

Ludwig, Karin; Kathmann, Norbert; Sterzer, Philipp; Hesselmann, Guido

2015-01-01

Recent behavioral and neuroimaging studies using continuous flash suppression (CFS) have suggested that action-related processing in the dorsal visual stream might be independent of perceptual awareness, in line with the "vision-for-perception" versus "vision-for-action" distinction of the influential dual-stream theory. It remains controversial if evidence suggesting exclusive dorsal stream processing of tool stimuli under CFS can be explained by their elongated shape alone or by action-relevant category representations in dorsal visual cortex. To approach this question, we investigated category- and shape-selective functional magnetic resonance imaging-blood-oxygen level-dependent responses in both visual streams using images of faces and tools. Multivariate pattern analysis showed enhanced decoding of elongated relative to non-elongated tools, both in the ventral and dorsal visual stream. The second aim of our study was to investigate whether the depth of interocular suppression might differentially affect processing in dorsal and ventral areas. However, parametric modulation of suppression depth by varying the CFS mask contrast did not yield any evidence for differential modulation of category-selective activity. Together, our data provide evidence for shape-selective processing under CFS in both dorsal and ventral stream areas and, therefore, do not support the notion that dorsal "vision-for-action" processing is exclusively preserved under interocular suppression. © 2014 Wiley Periodicals, Inc.

Bovine Milk as a Source of Functional Oligosaccharides for Improving Human Health12

PubMed Central

Zivkovic, Angela M.; Barile, Daniela

2011-01-01

Human milk oligosaccharides are complex sugars that function as selective growth substrates for specific beneficial bacteria in the gastrointestinal system. Bovine milk is a potentially excellent source of commercially viable analogs of these unique molecules. However, bovine milk has a much lower concentration of these oligosaccharides than human milk, and the majority of the molecules are simpler in structure than those found in human milk. Specific structural characteristics of milk-derived oligosaccharides are crucial to their ability to selectively enrich beneficial bacteria while inhibiting or being less than ideal substrates for undesirable and pathogenic bacteria. Thus, if bovine milk products are to provide human milk–like benefits, it is important to identify specific dairy streams that can be processed commercially and cost-effectively and that can yield specific oligosaccharide compositions that will be beneficial as new food ingredients or supplements to improve human health. Whey streams have the potential to be commercially viable sources of complex oligosaccharides that have the structural resemblance and diversity of the bioactive oligosaccharides in human milk. With further refinements to dairy stream processing techniques and functional testing to identify streams that are particularly suitable for enriching beneficial intestinal bacteria, the future of oligosaccharides isolated from dairy streams as a food category with substantiated health claims is promising. PMID:22332060

Bovine milk as a source of functional oligosaccharides for improving human health.

PubMed

Zivkovic, Angela M; Barile, Daniela

2011-05-01

Human milk oligosaccharides are complex sugars that function as selective growth substrates for specific beneficial bacteria in the gastrointestinal system. Bovine milk is a potentially excellent source of commercially viable analogs of these unique molecules. However, bovine milk has a much lower concentration of these oligosaccharides than human milk, and the majority of the molecules are simpler in structure than those found in human milk. Specific structural characteristics of milk-derived oligosaccharides are crucial to their ability to selectively enrich beneficial bacteria while inhibiting or being less than ideal substrates for undesirable and pathogenic bacteria. Thus, if bovine milk products are to provide human milk-like benefits, it is important to identify specific dairy streams that can be processed commercially and cost-effectively and that can yield specific oligosaccharide compositions that will be beneficial as new food ingredients or supplements to improve human health. Whey streams have the potential to be commercially viable sources of complex oligosaccharides that have the structural resemblance and diversity of the bioactive oligosaccharides in human milk. With further refinements to dairy stream processing techniques and functional testing to identify streams that are particularly suitable for enriching beneficial intestinal bacteria, the future of oligosaccharides isolated from dairy streams as a food category with substantiated health claims is promising.

On the organization of the perisylvian cortex: Insights from the electrophysiology of language. Comment on "Towards a Computational Comparative Neuroprimatology: Framing the language-ready brain" by M.A. Arbib

NASA Astrophysics Data System (ADS)

Brouwer, Harm; Crocker, Matthew W.

2016-03-01

The Mirror System Hypothesis (MSH) on the evolution of the language-ready brain draws upon the parallel dorsal-ventral stream architecture for vision [1]. The dorsal ;how; stream provides a mapping of parietally-mediated affordances onto the motor system (supporting preshape), whereas the ventral ;what; stream engages in object recognition and visual scene analysis (supporting pantomime and verbal description). Arbib attempts to integrate this MSH perspective with a recent conceptual dorsal-ventral stream model of auditory language comprehension [5] (henceforth, the B&S model). In the B&S model, the dorsal stream engages in time-dependent combinatorial processing, which subserves syntactic structuring and linkage to action, whereas the ventral stream performs time-independent unification of conceptual schemata. These streams are integrated in the left Inferior Frontal Gyrus (lIFG), which is assumed to subserve cognitive control, and no linguistic processing functions. Arbib criticizes the B&S model on two grounds: (i) the time-independence of the semantic processing in the ventral stream (by arguing that semantic processing is just as time-dependent as syntactic processing), and (ii) the absence of linguistic processing in the lIFG (reconciling syntactic and semantic representations is very much linguistic processing proper). Here, we provide further support for these two points of criticism on the basis of insights from the electrophysiology of language. In the course of our argument, we also sketch the contours of an alternative model that may prove better suited for integration with the MSH.

Stream microbial diversity in response to environmental changes: review and synthesis of existing research

PubMed Central

Zeglin, Lydia H.

2015-01-01

The importance of microbial activity to ecosystem function in aquatic ecosystems is well established, but microbial diversity has been less frequently addressed. This review and synthesis of 100s of published studies on stream microbial diversity shows that factors known to drive ecosystem processes, such as nutrient availability, hydrology, metal contamination, contrasting land-use and temperature, also cause heterogeneity in bacterial diversity. Temporal heterogeneity in stream bacterial diversity was frequently observed, reflecting the dynamic nature of both stream ecosystems and microbial community composition. However, within-stream spatial differences in stream bacterial diversity were more commonly observed, driven specifically by different organic matter (OM) compartments. Bacterial phyla showed similar patterns in relative abundance with regard to compartment type across different streams. For example, surface water contained the highest relative abundance of Actinobacteria, while epilithon contained the highest relative abundance of Cyanobacteria and Bacteroidetes. This suggests that contrasting physical and/or nutritional habitats characterized by different stream OM compartment types may select for certain bacterial lineages. When comparing the prevalence of physicochemical effects on stream bacterial diversity, effects of changing metal concentrations were most, while effects of differences in nutrient concentrations were least frequently observed. This may indicate that although changing nutrient concentrations do tend to affect microbial diversity, other environmental factors are more likely to alter stream microbial diversity and function. The common observation of connections between ecosystem process drivers and microbial diversity suggests that microbial taxonomic turnover could mediate ecosystem-scale responses to changing environmental conditions, including both microbial habitat distribution and physicochemical factors. PMID:26042102

Stream Processors

NASA Astrophysics Data System (ADS)

Erez, Mattan; Dally, William J.

Stream processors, like other multi core architectures partition their functional units and storage into multiple processing elements. In contrast to typical architectures, which contain symmetric general-purpose cores and a cache hierarchy, stream processors have a significantly leaner design. Stream processors are specifically designed for the stream execution model, in which applications have large amounts of explicit parallel computation, structured and predictable control, and memory accesses that can be performed at a coarse granularity. Applications in the streaming model are expressed in a gather-compute-scatter form, yielding programs with explicit control over transferring data to and from on-chip memory. Relying on these characteristics, which are common to many media processing and scientific computing applications, stream architectures redefine the boundary between software and hardware responsibilities with software bearing much of the complexity required to manage concurrency, locality, and latency tolerance. Thus, stream processors have minimal control consisting of fetching medium- and coarse-grained instructions and executing them directly on the many ALUs. Moreover, the on-chip storage hierarchy of stream processors is under explicit software control, as is all communication, eliminating the need for complex reactive hardware mechanisms.

Environmental controls of wood entrapment in upper Midwestern streams

USGS Publications Warehouse

Merten, Eric C.; Finlay, Jacques; Johnson, Lucinda; Newman, Raymond; Stefan, Heinz; Vondracek, Bruce C.

2011-01-01

Wood deposited in streams provides a wide variety of ecosystem functions, including enhancing habitat for key species in stream food webs, increasing geomorphic and hydraulic heterogeneity and retaining organic matter. Given the strong role that wood plays in streams, factors that influence wood inputs, retention and transport are critical to stream ecology. Wood entrapment, the process of wood coming to rest after being swept downstream at least 10 m, is poorly understood, yet important for predicting stream function and success of restoration efforts. Data on entrapment were collected for a wide range of natural wood pieces (n = 344), stream geomorphology and hydraulic conditions in nine streams along the north shore of Lake Superior in Minnesota. Locations of pieces were determined in summer 2007 and again following an overbank stormflow event in fall 2007. The ratio of piece length to effective stream width (length ratio) and the weight of the piece were important in a multiple logistic regression model that explained 25% of the variance in wood entrapment. Entrapment remains difficult to predict in natural streams, and often may simply occur wherever wood pieces are located when high water recedes. However, this study can inform stream modifications to discourage entrapment at road crossings or other infrastructure by applying the model formula to estimate the effective width required to pass particular wood pieces. Conversely, these results could also be used to determine conditions (e.g. pre-existing large, stable pieces) that encourage entrapment where wood is valued for ecological functions.

Electrophysiological Evidence for Ventral Stream Deficits in Schizophrenia Patients

PubMed Central

Plomp, Gijs; Roinishvili, Maya; Chkonia, Eka; Kapanadze, George; Kereselidze, Maia; Brand, Andreas; Herzog, Michael H.

2013-01-01

Schizophrenic patients suffer from many deficits including visual, attentional, and cognitive ones. Visual deficits are of particular interest because they are at the fore-end of information processing and can provide clear examples of interactions between sensory, perceptual, and higher cognitive functions. Visual deficits in schizophrenic patients are often attributed to impairments in the dorsal (where) rather than the ventral (what) stream of visual processing. We used a visual-masking paradigm in which patients and matched controls discriminated small vernier offsets. We analyzed the evoked electroencephalography (EEG) responses and applied distributed electrical source imaging techniques to estimate activity differences between conditions and groups throughout the brain. Compared with controls, patients showed strongly reduced discrimination accuracy, confirming previous work. The behavioral deficits corresponded to pronounced decreases in the evoked EEG response at around 200 ms after stimulus onset. At this latency, patients showed decreased activity for targets in left parietal cortex (dorsal stream), but the decrease was most pronounced in lateral occipital cortex (in the ventral stream). These deficiencies occurred at latencies that reflect object processing and fine shape discriminations. We relate the reduced ventral stream activity to deficient top-down processing of target stimuli and provide a framework for relating the commonly observed dorsal stream deficiencies with the currently observed ventral stream deficiencies. PMID:22258884

Electrophysiological evidence for ventral stream deficits in schizophrenia patients.

PubMed

Plomp, Gijs; Roinishvili, Maya; Chkonia, Eka; Kapanadze, George; Kereselidze, Maia; Brand, Andreas; Herzog, Michael H

2013-05-01

Schizophrenic patients suffer from many deficits including visual, attentional, and cognitive ones. Visual deficits are of particular interest because they are at the fore-end of information processing and can provide clear examples of interactions between sensory, perceptual, and higher cognitive functions. Visual deficits in schizophrenic patients are often attributed to impairments in the dorsal (where) rather than the ventral (what) stream of visual processing. We used a visual-masking paradigm in which patients and matched controls discriminated small vernier offsets. We analyzed the evoked electroencephalography (EEG) responses and applied distributed electrical source imaging techniques to estimate activity differences between conditions and groups throughout the brain. Compared with controls, patients showed strongly reduced discrimination accuracy, confirming previous work. The behavioral deficits corresponded to pronounced decreases in the evoked EEG response at around 200 ms after stimulus onset. At this latency, patients showed decreased activity for targets in left parietal cortex (dorsal stream), but the decrease was most pronounced in lateral occipital cortex (in the ventral stream). These deficiencies occurred at latencies that reflect object processing and fine shape discriminations. We relate the reduced ventral stream activity to deficient top-down processing of target stimuli and provide a framework for relating the commonly observed dorsal stream deficiencies with the currently observed ventral stream deficiencies.

Spatial and temporal patterns of stream burial and its effect on habitat connectivity across headwater stream communities of the Potomac River Basin, USA

NASA Astrophysics Data System (ADS)

Weitzell, R.; Guinn, S. M.; Elmore, A. J.

2012-12-01

The process of directing streams into culverts, pipes, or concrete-lined ditches during urbanization, known as stream burial, alters the primary physical, chemical, and biological processes of streams. Knowledge of the cumulative impacts of reduced structure and ecological function within buried stream networks is crucial for informing management of stream ecosystems, in light of continued growth in urban areas, and the uncertain response of freshwater ecosystems to the stresses of global climate change. To address this need, we utilized recently improved stream maps for the Potomac River Basin (PRB) to describe the extent and severity of stream burial across the basin. Observations of stream burial made from high resolution aerial photographs (>1% of total basin area) and a decision tree using spatial statistics from impervious cover data were used to predict stream burial at 4 time-steps (1975, 1990, 2001, 2006). Of the roughly 95,500 kilometers (km) of stream in the PRB, approximately 4551 km (4.76%) were buried by urban development as of 2001. Analysis of county-level burial trends shows differential patterns in the timing and rates of headwater stream burial, which may be due to local development policies, topographical constraints, and/or time since development. Consistently higher rates of stream burial were observed for small streams, decreasing with stream order. Headwater streams (1st-2nd order) are disproportionately affected, with burial rates continuing to increase over time in relation to larger stream orders. Beyond simple habitat loss, headwater burial decreases connectivity among headwater populations and habitats, with potential to affect a wide range of important ecological processes. To quantify changes to regional headwater connectivity we applied a connectivity model based on electrical circuit theory. Circuit-theoretical models function by treating the landscape as a resistance surface, representing hypothesized relationships between landscape features and their differential "resistance" to movement by organisms. A landscape resistance layer was developed and fine-tuned in terms of the habitat use/needs of aquatic invertebrates with terrestrial adult stages, organisms of critical importance to riparian and aquatic ecosystem health. Initial results show significant increases in landscape resistance (isolation) among headwater systems, and corresponding decreases in current flow (movement of organisms) across the increasingly urbanized PRB landscape. Of particular interest, the circuit model highlighted the importance of stream confluences and zero-order (non-channel) headwater areas for movement of organisms between headwater systems that are otherwise highly disconnected, and for which the latter currently receives no legal protection from development.

Integrated Water Flow Model (IWFM), A Tool For Numerically Simulating Linked Groundwater, Surface Water And Land-Surface Hydrologic Processes

NASA Astrophysics Data System (ADS)

Dogrul, E. C.; Brush, C. F.; Kadir, T. N.

2006-12-01

The Integrated Water Flow Model (IWFM) is a comprehensive input-driven application for simulating groundwater flow, surface water flow and land-surface hydrologic processes, and interactions between these processes, developed by the California Department of Water Resources (DWR). IWFM couples a 3-D finite element groundwater flow process and 1-D land surface, lake, stream flow and vertical unsaturated-zone flow processes which are solved simultaneously at each time step. The groundwater flow system is simulated as a multilayer aquifer system with a mixture of confined and unconfined aquifers separated by semiconfining layers. The groundwater flow process can simulate changing aquifer conditions (confined to unconfined and vice versa), subsidence, tile drains, injection wells and pumping wells. The land surface process calculates elemental water budgets for agricultural, urban, riparian and native vegetation classes. Crop water demands are dynamically calculated using distributed soil properties, land use and crop data, and precipitation and evapotranspiration rates. The crop mix can also be automatically modified as a function of pumping lift using logit functions. Surface water diversions and groundwater pumping can each be specified, or can be automatically adjusted at run time to balance water supply with water demand. The land-surface process also routes runoff to streams and deep percolation to the unsaturated zone. Surface water networks are specified as a series of stream nodes (coincident with groundwater nodes) with specified bed elevation, conductance and stage-flow relationships. Stream nodes are linked to form stream reaches. Stream inflows at the model boundary, surface water diversion locations, and one or more surface water deliveries per location are specified. IWFM routes stream flows through the network, calculating groundwater-surface water interactions, accumulating inflows from runoff, and allocating available stream flows to meet specified or calculated deliveries. IWFM utilizes a very straight-forward input file structure, allowing rapid development of complex simulations. A key feature of IWFM is a new algorithm for computation of groundwater flow across element faces. Enhancements to version 3.0 include automatic time-tracking of input and output data sets, linkage with the HEC-DSS database, and dynamic crop allocation using logit functions. Utilities linking IWFM to the PEST automated calibration suite are also available. All source code, executables and documentation are available for download from the DWR web site. IWFM is currently being used to develop hydrologic simulations of California's Central Valley (C2VSIM); the west side of California's San Joaquin Valley (WESTSIM); Butte County, CA; Solano County, CA; Merced County, CA; and the Oregon side of the Walla Walla River Basin.

Processing reafferent and exafferent visual information for action and perception.

PubMed

Reichenbach, Alexandra; Diedrichsen, Jörn

2015-01-01

A recent study suggests that reafferent hand-related visual information utilizes a privileged, attention-independent processing channel for motor control. This process was termed visuomotor binding to reflect its proposed function: linking visual reafferences to the corresponding motor control centers. Here, we ask whether the advantage of processing reafferent over exafferent visual information is a specific feature of the motor processing stream or whether the improved processing also benefits the perceptual processing stream. Human participants performed a bimanual reaching task in a cluttered visual display, and one of the visual hand cursors could be displaced laterally during the movement. We measured the rapid feedback responses of the motor system as well as matched perceptual judgments of which cursor was displaced. Perceptual judgments were either made by watching the visual scene without moving or made simultaneously to the reaching tasks, such that the perceptual processing stream could also profit from the specialized processing of reafferent information in the latter case. Our results demonstrate that perceptual judgments in the heavily cluttered visual environment were improved when performed based on reafferent information. Even in this case, however, the filtering capability of the perceptual processing stream suffered more from the increasing complexity of the visual scene than the motor processing stream. These findings suggest partly shared and partly segregated processing of reafferent information for vision for motor control versus vision for perception.

Development of the Hydroecological Integrity Assessment Process for Determining Environmental Flows for New Jersey Streams

USGS Publications Warehouse

Kennen, Jonathan G.; Henriksen, James A.; Nieswand, Steven P.

2007-01-01

The natural flow regime paradigm and parallel stream ecological concepts and theories have established the benefits of maintaining or restoring the full range of natural hydrologic variation for physiochemical processes, biodiversity, and the evolutionary potential of aquatic and riparian communities. A synthesis of recent advances in hydroecological research coupled with stream classification has resulted in a new process to determine environmental flows and assess hydrologic alteration. This process has national and international applicability. It allows classification of streams into hydrologic stream classes and identification of a set of non-redundant and ecologically relevant hydrologic indices for 10 critical sub-components of flow. Three computer programs have been developed for implementing the Hydroecological Integrity Assessment Process (HIP): (1) the Hydrologic Indices Tool (HIT), which calculates 171 ecologically relevant hydrologic indices on the basis of daily-flow and peak-flow stream-gage data; (2) the New Jersey Hydrologic Assessment Tool (NJHAT), which can be used to establish a hydrologic baseline period, provide options for setting baseline environmental-flow standards, and compare past and proposed streamflow alterations; and (3) the New Jersey Stream Classification Tool (NJSCT), designed for placing unclassified streams into pre-defined stream classes. Biological and multivariate response models including principal-component, cluster, and discriminant-function analyses aided in the development of software and implementation of the HIP for New Jersey. A pilot effort is currently underway by the New Jersey Department of Environmental Protection in which the HIP is being used to evaluate the effects of past and proposed surface-water use, ground-water extraction, and land-use changes on stream ecosystems while determining the most effective way to integrate the process into ongoing regulatory programs. Ultimately, this scientifically defensible process will help to quantify the effects of anthropogenic changes and development on hydrologic variability and help planners and resource managers balance current and future water requirements with ecological needs.

Leaf litter breakdown, microbial respiration and shredder production in metal-polluted streams

USGS Publications Warehouse

Carlisle, D.M.; Clements, W.H.

2005-01-01

1. If species disproportionately influence ecosystem functioning and also differ in their sensitivities to environmental conditions, the selective removal of species by anthropogenic stressors may lead to strong effects on ecosystem processes. We evaluated whether these circumstances held for several Colorado, U.S.A. streams stressed by Zn. 2. Benthic invertebrates and chemistry were sampled in five second-third order streams for 1 year. Study streams differed in dissolved metal concentrations, but were otherwise similar in chemical and physical characteristics. Secondary production of leaf-shredding insects was estimated using the increment summation and size-frequency methods. Leaf litter breakdown rates were estimated by retrieving litter-bags over a 171 day period. Microbial activity on leaf litter was measured in the laboratory using changes in oxygen concentration over a 48 h incubation period. 3. Dissolved Zn concentrations varied eightfold among two reference and three polluted streams. Total secondary production of shredders was negatively associated with metal contamination. Secondary production in reference streams was dominated by Taenionema pallidum. Results of previous studies and the current investigation demonstrate that this shredder is highly sensitive to metals in Colorado headwater streams. Leaf litter breakdown rates were similar between reference streams and declined significantly in the polluted streams. Microbial respiration at the most contaminated site was significantly lower than at reference sites. 4. Our results supported the hypothesis that some shredder species contribute disproportionately to leaf litter breakdown. Furthermore, the functionally dominant taxon was also the most sensitive to metal contamination. We conclude that leaf litter breakdown in our study streams lacked functional redundancy and was therefore highly sensitive to contaminant-induced alterations in community structure. We argue for the necessity of simultaneously measuring community structure and ecosystem function in anthropogenically stressed ecosystems.

Quantifying the sensitivity of ephemeral streams to land disturbance activities in arid ecosystems at the watershed scale.

PubMed

O'Connor, Ben L; Hamada, Yuki; Bowen, Esther E; Grippo, Mark A; Hartmann, Heidi M; Patton, Terri L; Van Lonkhuyzen, Robert A; Carr, Adrianne E

2014-11-01

Large areas of public lands administered by the Bureau of Land Management and located in arid regions of the southwestern United States are being considered for the development of utility-scale solar energy facilities. Land-disturbing activities in these desert, alluvium-filled valleys have the potential to adversely affect the hydrologic and ecologic functions of ephemeral streams. Regulation and management of ephemeral streams typically falls under a spectrum of federal, state, and local programs, but scientifically based guidelines for protecting ephemeral streams with respect to land-development activities are largely nonexistent. This study developed an assessment approach for quantifying the sensitivity to land disturbance of ephemeral stream reaches located in proposed solar energy zones (SEZs). The ephemeral stream assessment approach used publicly-available geospatial data on hydrology, topography, surficial geology, and soil characteristics, as well as high-resolution aerial imagery. These datasets were used to inform a professional judgment-based score index of potential land disturbance impacts on selected critical functions of ephemeral streams, including flow and sediment conveyance, ecological habitat value, and groundwater recharge. The total sensitivity scores (sum of scores for the critical stream functions of flow and sediment conveyance, ecological habitats, and groundwater recharge) were used to identify highly sensitive stream reaches to inform decisions on developable areas in SEZs. Total sensitivity scores typically reflected the scores of the individual stream functions; some exceptions pertain to groundwater recharge and ecological habitats. The primary limitations of this assessment approach were the lack of high-resolution identification of ephemeral stream channels in the existing National Hydrography Dataset, and the lack of mechanistic processes describing potential impacts on ephemeral stream functions at the watershed scale. The primary strength of this assessment approach is that it allows watershed-scale planning for low-impact development in arid ecosystems; the qualitative scoring of potential impacts can also be adjusted to accommodate new geospatial data, and to allow for expert and stakeholder input into decisions regarding the identification and potential avoidance of highly sensitive stream reaches.

Quantifying the sensitivity of ephemeral streams to land disturbance activities in arid ecosystems at the watershed scale

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

O’Connor, Ben L.; Hamada, Yuki; Bowen, Esther E.

2014-08-17

Large areas of public lands administered by the Bureau of Land Management and located in arid regions of the southwestern United States are being considered for the development of utility-scale solar energy facilities. Land-disturbing activities in these desert, alluvium-filled valleys have the potential to adversely affect the hydrologic and ecologic functions of ephemeral streams. Regulation and management of ephemeral streams typically falls under a spectrum of federal, state, and local programs, but scientifically based guidelines for protecting ephemeral streams with respect to land-development activities are largely nonexistent. This study developed an assessment approach for quantifying the sensitivity to land disturbancemore » of ephemeral stream reaches located in proposed solar energy zones (SEZs). The ephemeral stream assessment approach used publicly-available geospatial data on hydrology, topography, surficial geology, and soil characteristics, as well as highresolution aerial imagery. These datasets were used to inform a professional judgment-based score index of potential land disturbance impacts on selected critical functions of ephemeral streams, including flow and sediment conveyance, ecological habitat value, and groundwater recharge. The total sensitivity scores (sum of scores for the critical stream functions of flow and sediment conveyance, ecological habitats, and groundwater recharge) were used to identify highly sensitive stream reaches to inform decisions on developable areas in SEZs. Total sensitivity scores typically reflected the scores of the individual stream functions; some exceptions pertain to groundwater recharge and ecological habitats. The primary limitations of this assessment approach were the lack of high-resolution identification of ephemeral stream channels in the existing National Hydrography Dataset, and the lack of mechanistic processes describing potential impacts on ephemeral stream functions at the watershed scale.The primary strength of this assessment approach is that it allows watershed-scale planning for low-impact development in arid ecosystems; the qualitative scoring of potential impacts can also be adjusted to accommodate new geospatial data, and to allow for expert and stakeholder input into decisions regarding the identification and potential avoidance of highly sensitive stream reaches.« less

Neurobiological roots of language in primate audition: common computational properties.

PubMed

Bornkessel-Schlesewsky, Ina; Schlesewsky, Matthias; Small, Steven L; Rauschecker, Josef P

2015-03-01

Here, we present a new perspective on an old question: how does the neurobiology of human language relate to brain systems in nonhuman primates? We argue that higher-order language combinatorics, including sentence and discourse processing, can be situated in a unified, cross-species dorsal-ventral streams architecture for higher auditory processing, and that the functions of the dorsal and ventral streams in higher-order language processing can be grounded in their respective computational properties in primate audition. This view challenges an assumption, common in the cognitive sciences, that a nonhuman primate model forms an inherently inadequate basis for modeling higher-level language functions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Getting a handle on virtual tools: An examination of the neuronal activity associated with virtual tool use.

PubMed

Rallis, Austin; Fercho, Kelene A; Bosch, Taylor J; Baugh, Lee A

2018-01-31

Tool use is associated with three visual streams-dorso-dorsal, ventro-dorsal, and ventral visual streams. These streams are involved in processing online motor planning, action semantics, and tool semantics features, respectively. Little is known about the way in which the brain represents virtual tools. To directly assess this question, a virtual tool paradigm was created that provided the ability to manipulate tool components in isolation of one another. During functional magnetic resonance imaging (fMRI), adult participants performed a series of virtual tool manipulation tasks in which vision and movement kinematics of the tool were manipulated. Reaction time and hand movement direction were monitored while the tasks were performed. Functional imaging revealed that activity within all three visual streams was present, in a similar pattern to what would be expected with physical tool use. However, a previously unreported network of right-hemisphere activity was found including right inferior parietal lobule, middle and superior temporal gyri and supramarginal gyrus - regions well known to be associated with tool processing within the left hemisphere. These results provide evidence that both virtual and physical tools are processed within the same brain regions, though virtual tools recruit bilateral tool processing regions to a greater extent than physical tools. Copyright © 2017 Elsevier Ltd. All rights reserved.

Normal form from biological motion despite impaired ventral stream function.

PubMed

Gilaie-Dotan, S; Bentin, S; Harel, M; Rees, G; Saygin, A P

2011-04-01

We explored the extent to which biological motion perception depends on ventral stream integration by studying LG, an unusual case of developmental visual agnosia. LG has significant ventral stream processing deficits but no discernable structural cortical abnormality. LG's intermediate visual areas and object-sensitive regions exhibit abnormal activation during visual object perception, in contrast to area V5/MT+ which responds normally to visual motion (Gilaie-Dotan, Perry, Bonneh, Malach, & Bentin, 2009). Here, in three studies we used point light displays, which require visual integration, in adaptive threshold experiments to examine LG's ability to detect form from biological and non-biological motion cues. LG's ability to detect and discriminate form from biological motion was similar to healthy controls. In contrast, he was significantly deficient in processing form from non-biological motion. Thus, LG can rely on biological motion cues to perceive human forms, but is considerably impaired in extracting form from non-biological motion. Finally, we found that while LG viewed biological motion, activity in a network of brain regions associated with processing biological motion was functionally correlated with his V5/MT+ activity, indicating that normal inputs from V5/MT+ might suffice to activate his action perception system. These results indicate that processing of biologically moving form can dissociate from other form processing in the ventral pathway. Furthermore, the present results indicate that integrative ventral stream processing is necessary for uncompromised processing of non-biological form from motion. Copyright © 2011 Elsevier Ltd. All rights reserved.

Brainstem origins for cortical 'what' and 'where' pathways in the auditory system.

PubMed

Kraus, Nina; Nicol, Trent

2005-04-01

We have developed a data-driven conceptual framework that links two areas of science: the source-filter model of acoustics and cortical sensory processing streams. The source-filter model describes the mechanics behind speech production: the identity of the speaker is carried largely in the vocal cord source and the message is shaped by the ever-changing filters of the vocal tract. Sensory processing streams, popularly called 'what' and 'where' pathways, are well established in the visual system as a neural scheme for separately carrying different facets of visual objects, namely their identity and their position/motion, to the cortex. A similar functional organization has been postulated in the auditory system. Both speaker identity and the spoken message, which are simultaneously conveyed in the acoustic structure of speech, can be disentangled into discrete brainstem response components. We argue that these two response classes are early manifestations of auditory 'what' and 'where' streams in the cortex. This brainstem link forges a new understanding of the relationship between the acoustics of speech and cortical processing streams, unites two hitherto separate areas in science, and provides a model for future investigations of auditory function.

Disentangling the pathways of land use impacts on the functional structure of fish assemblages in Amazon streams

EPA Science Inventory

Agricultural land use is a primary driver of environmental impacts on streams. However, the causal processes that shape these impacts operate through multiple pathways and at several spatial scales. This complexity undermines the development of more effective management approache...

Adaptations to vision-for-action in primate brain evolution: Comment on "Towards a Computational Comparative Neuroprimatology: Framing the language-ready brain" by Michael A. Arbib

NASA Astrophysics Data System (ADS)

Hecht, Erin

2016-03-01

As Arbib [1] notes, the two-streams hypothesis [5] has provided a powerful explanatory framework for understanding visual processing. The inferotemporal ventral stream recognizes objects and agents - ;what; one is seeing. The dorsal ;how; or ;where; stream through parietal cortex processes motion, spatial location, and visuo-proprioceptive relationships - ;vision for action.; Hickock and Poeppel's [3] extension of this model to the auditory system raises the question of deeper, multi- or supra-sensory themes in dorsal vs. ventral processing. Petrides and Pandya [10] postulate that the evolution of language may have been influenced by the fact that the dorsal stream terminates in posterior Broca's area (BA44) while the ventral stream terminates in anterior Broca's area (BA45). In an intriguing potential parallel, a recent ALE metanalysis of 54 fMRI studies found that semantic processing is located more anteriorly and superiorly than syntactic processing in Broca's area [13]. But clearly, macaques do not have language, nor other likely pre- or co-adaptations to language, such as complex imitation and tool use. What changed in the brain that enabled these functions to evolve?

Interaction between dorsal and ventral processing streams: where, when and how?

PubMed

Cloutman, Lauren L

2013-11-01

The execution of complex visual, auditory, and linguistic behaviors requires a dynamic interplay between spatial ('where/how') and non-spatial ('what') information processed along the dorsal and ventral processing streams. However, while it is acknowledged that there must be some degree of interaction between the two processing networks, how they interact, both anatomically and functionally, is a question which remains little explored. The current review examines the anatomical, temporal, and behavioral evidence regarding three potential models of dual stream interaction: (1) computations along the two pathways proceed independently and in parallel, reintegrating within shared target brain regions; (2) processing along the separate pathways is modulated by the existence of recurrent feedback loops; and (3) information is transferred directly between the two pathways at multiple stages and locations along their trajectories. Copyright © 2012 Elsevier Inc. All rights reserved.

Diel biogeochemical processes and their effect on the aqueous chemistry of streams: A review

USGS Publications Warehouse

Nimick, David A.; Gammons, Christopher H.; Parker, Stephen R.

2011-01-01

This review summarizes biogeochemical processes that operate on diel, or 24-h, time scales in streams and the changes in aqueous chemistry that are associated with these processes. Some biogeochemical processes, such as those producing diel cycles of dissolved O2 and pH, were the first to be studied, whereas processes producing diel concentration cycles of a broader spectrum of chemical species including dissolved gases, dissolved inorganic and organic carbon, trace elements, nutrients, stable isotopes, and suspended particles have received attention only more recently. Diel biogeochemical cycles are interrelated because the cyclical variations produced by one biogeochemical process commonly affect another. Thus, understanding biogeochemical cycling is essential not only for guiding collection and interpretation of water-quality data but also for geochemical and ecological studies of streams. Expanded knowledge of diel biogeochemical cycling will improve understanding of how natural aquatic environments function and thus lead to better predictions of how stream ecosystems might react to changing conditions of contaminant loading, eutrophication, climate change, drought, industrialization, development, and other factors.

Light availability affects stream biofilm bacterial community composition and function, but not diversity

PubMed Central

Wagner, Karoline; Besemer, Katharina; Burns, Nancy R.; Battin, Tom J.

2015-01-01

Summary Changes in riparian vegetation or water turbidity and browning in streams alter the local light regime with potential implications for stream biofilms and ecosystem functioning. We experimented with biofilms in microcosms grown under a gradient of light intensities (range: 5–152 μmole photons s−1 m−2) and combined 454‐pyrosequencing and enzymatic activity assays to evaluate the effects of light on biofilm structure and function. We observed a shift in bacterial community composition along the light gradient, whereas there was no apparent change in alpha diversity. Multifunctionality, based on extracellular enzymes, was highest under high light conditions and decoupled from bacterial diversity. Phenol oxidase activity, involved in the degradation of polyphenolic compounds, was twice as high on average under the lowest compared with the highest light condition. This suggests a shift in reliance of microbial heterotrophs on biofilm phototroph‐derived organic matter under high light availability to more complex organic matter under low light. Furthermore, extracellular enzyme activities correlated with nutrient cycling and community respiration, supporting the link between biofilm structure–function and biogeochemical fluxes in streams. Our findings demonstrate that changes in light availability are likely to have significant impacts on biofilm structure and function, potentially affecting stream ecosystem processes. PMID:26013911

Chapter 6: Temperature

USGS Publications Warehouse

Jones, Leslie A.; Muhlfeld, Clint C.; Hauer, F. Richard; F. Richard Hauer,; Lamberti, G.A.

2017-01-01

Stream temperature has direct and indirect effects on stream ecology and is critical in determining both abiotic and biotic system responses across a hierarchy of spatial and temporal scales. Temperature variation is primarily driven by solar radiation, while landscape topography, geology, and stream reach scale ecosystem processes contribute to local variability. Spatiotemporal heterogeneity in freshwater ecosystems influences habitat distributions, physiological functions, and phenology of all aquatic organisms. In this chapter we provide an overview of methods for monitoring stream temperature, characterization of thermal profiles, and modeling approaches to stream temperature prediction. Recent advances in temperature monitoring allow for more comprehensive studies of the underlying processes influencing annual variation of temperatures and how thermal variability may impact aquatic organisms at individual, population, and community based scales. Likewise, the development of spatially explicit predictive models provide a framework for simulating natural and anthropogenic effects on thermal regimes which is integral for sustainable management of freshwater systems.

Monitoring Ephemeral Streams Using Airborne Very High Resolution Multispectral Remote Sensing in Arid Environments

NASA Astrophysics Data System (ADS)

Hamada, Y.; O'Connor, B. L.

2012-12-01

Development in arid environments often results in the loss and degradation of the ephemeral streams that provide habitat and critical ecosystem functions such as water delivery, sediment transport, and groundwater recharge. Quantification of these ecosystem functions is challenging because of the episodic nature of runoff events in desert landscapes and the large spatial scale of watersheds that potentially can be impacted by large-scale development. Low-impact development guidelines and regulatory protection of ephemeral streams are often lacking due to the difficulty of accurately mapping and quantifying the critical functions of ephemeral streams at scales larger than individual reaches. Renewable energy development in arid regions has the potential to disturb ephemeral streams at the watershed scale, and it is necessary to develop environmental monitoring applications for ephemeral streams to help inform land management and regulatory actions aimed at protecting and mitigating for impacts related to large-scale land disturbances. This study focuses on developing remote sensing methodologies to identify and monitor impacts on ephemeral streams resulting from the land disturbance associated with utility-scale solar energy development in the desert southwest of the United States. Airborne very high resolution (VHR) multispectral imagery is used to produce stereoscopic, three-dimensional landscape models that can be used to (1) identify and map ephemeral stream channel networks, and (2) support analyses and models of hydrologic and sediment transport processes that pertain to the critical functionality of ephemeral streams. Spectral and statistical analyses are being developed to extract information about ephemeral channel location and extent, micro-topography, riparian vegetation, and soil moisture characteristics. This presentation will demonstrate initial results and provide a framework for future work associated with this project, for developing the necessary field measurements necessary to verify remote sensing landscape models, and for generating hydrologic models and analyses.

Connectivity and seasonality cause rapid taxonomic and functional trait succession within an invertebrate community after stream restoration

PubMed Central

van der Geest, Harm G.; van Loon, E. Emiel; Verdonschot, Piet F. M.

2018-01-01

General colonization concepts consent that a slow process of microhabitat formation and subsequent niche realization occurs during early stages after new habitat is released. Subsequently, only few species are able to colonize new habitat in the early onset of succession, while species richness increases steadily over time. Although most colonization studies have been performed in terrestrial ecosystems, running water ecosystems are equally or even more prone to colonization after disturbance due to their dynamic nature. We question how invertebrate succession patterns reconcile with general colonization concepts. With this study we provide insight into the colonization process in newly created lowland stream trajectories and answer how within-stream bio- and functional diversity develops over time. Our results show a rapid influx of species, with a wide range of functional traits, during the first season after water flow commenced. During more than two years of regular monitoring, immigration rates were highest in autumn, marking the effects of seasonality on invertebrate dispersal. Biodiversity increased while abundance peaks of species alternated between seasons. Moreover, also days since start of the experiment explains a considerable part of the variability for taxa as well as traits. However, the relative trait composition remained similar throughout the entire monitoring period and only few specific traits had significantly higher proportions during specific seasons. This indicates that first phase colonization in freshwater streams can be a very rapid process that results in a high biodiversity and a large variety of species functional characteristics from the early onset of succession, contradicting general terrestrial colonization theory. PMID:29795599

Parasite effects on isopod feeding rates can alter the host's functional role in a natural stream ecosystem.

PubMed

Hernandez, Alexander D; Sukhdeo, Michael V K

2008-05-01

Changes to host behaviour as a consequence of infection are common in many parasite-host associations, but their effects on the functional role hosts play within ecosystems are rarely quantified. This study reports that helminth parasites significantly decrease consumption of detritus by their isopod hosts in laboratory experiments. Natural host and parasite densities across eight contiguous seasons were used to estimate effects on the amount of stream detritus-energy processed. Extrapolations using mass-specific processing rates from laboratory results to field patterns suggest that the effects of the parasites occur year round but the greatest impact on the amount of detritus processed by isopods occurs in the autumn when the bulk of leaf detritus enters the stream, and when parasite prevalence in the isopod population is high. Parasites have a lesser impact on the amount of detritus processed in spring and summer when isopods are most abundant, when parasite prevalence is not high, and when fish predation on isopods is high. These results support the idea that parasites can affect the availability of resources critical to other species by altering behaviours related to the functional role hosts play in ecosystems, and suggest that seasonality may be an important factor to consider in the dynamics of these parasite-host interactions.

Functional Dissociations within the Ventral Object Processing Pathway: Cognitive Modules or a Hierarchical Continuum?

ERIC Educational Resources Information Center

Cowell, Rosemary A.; Bussey, Timothy J.; Saksida, Lisa M.

2010-01-01

We examined the organization and function of the ventral object processing pathway. The prevailing theoretical approach in this field holds that the ventral object processing stream has a modular organization, in which visual perception is carried out in posterior regions and visual memory is carried out, independently, in the anterior temporal…

Leaf breakdown in streams differing in catchment land use

USGS Publications Warehouse

Paul, M.J.; Meyer, J.L.; Couch, C.A.

2006-01-01

1. The impact of changes in land use on stream ecosystem function is poorly understood. We studied leaf breakdown, a fundamental process of stream ecosystems, in streams that represent a range of catchment land use in the Piedmont physiographic province of the south-eastern United States. 2. We placed bags of chalk maple (Acer barbatum) leaves in similar-sized streams in 12 catchments of differing dominant land use: four forested, three agricultural, two suburban and three urban catchments. We measured leaf mass, invertebrate abundance and fungal biomass in leaf bags over time. 3. Leaves decayed significantly faster in agricultural (0.0465 day-1) and urban (0.0474 day-1) streams than in suburban (0.0173 day-1) and forested (0.0100 day-1) streams. Additionally, breakdown rates in the agricultural and urban streams were among the fastest reported for deciduous leaves in any stream. Nutrient concentrations in agricultural streams were significantly higher than in any other land-use type. Fungal biomass associated with leaves was significantly lower in urban streams; while shredder abundance in leaf bags was significantly higher in forested and agricultural streams than in suburban and urban streams. Storm runoff was significantly higher in urban and suburban catchments that had higher impervious surface cover than forested or agricultural catchments. 4. We propose that processes accelerating leaf breakdown in agricultural and urban streams were not the same: faster breakdown in agricultural streams was due to increased biological activity as a result of nutrient enrichment, whereas faster breakdown in urban streams was a result of physical fragmentation resulting from higher storm runoff. ?? 2006 The Authors.

From bottles to stream reaches and networks: Consequences of scale in how we interpret the function of freshwaters in the carbon cycle

NASA Astrophysics Data System (ADS)

Hotchkiss, E. R.

2017-12-01

Freshwater biological processes can alter the quantity and quality of organic carbon (OC) inputs from land before they are transported downstream, but the relative role of hydrologic transport and in-stream processing is still not well quantified at the scale of fluvial networks. Despite much research on the role of biology and hydrology in governing the form and fate of C in inland waters, conclusions about the function of freshwater ecosystems in modifying OC still largely depend on where we draw our ecosystem boundaries, i.e., the spatial scale of measurements used to assess OC transformations. Here I review freshwater OC uptake rates derived from bioassay incubations, synoptic modeling, reach-scale experiments, and ecosystem OC spiraling estimates. Median OC uptake velocities from standard bioassay incubations (0.02 m/d) and synoptic modeling (0.04 m/d) are 1-2 orders of magnitude lower than reach-scale experimental DOC additions and ecosystem OC spiraling estimates (2.2 and 0.27 m/d, respectively) in streams and rivers. Together, ecosystem metabolism and OC fluxes can be used to estimate the distance OC travels before being consumed and respired as CO2 through biological processes (i.e., OC spiraling), allowing for a more mechanistic understanding of the role of ecosystem processes and hydrologic fluxes in modifying downstream OC transport. Beyond the reach scale, data from stream network and stream-lake-river modeling simulations show how we may use linked sampling sites within networks to better understand the integrated sources and fate of OC in freshwaters. We currently underestimate the role of upstream processes in contributing to downstream fluxes: moving from single-ecosystem comparisons to linked-ecosystem simulations increases the contribution of in situ OC processing to CO2 emissions from 30% to >40%. Insights from literature reviews, ecosystem process measurements, and model simulations provide a framework for future considerations of integrated C transport, transformations, and fate when scaling patterns and processes in inland waters.

Mapping a lateralization gradient within the ventral stream for auditory speech perception.

PubMed

Specht, Karsten

2013-01-01

Recent models on speech perception propose a dual-stream processing network, with a dorsal stream, extending from the posterior temporal lobe of the left hemisphere through inferior parietal areas into the left inferior frontal gyrus, and a ventral stream that is assumed to originate in the primary auditory cortex in the upper posterior part of the temporal lobe and to extend toward the anterior part of the temporal lobe, where it may connect to the ventral part of the inferior frontal gyrus. This article describes and reviews the results from a series of complementary functional magnetic resonance imaging studies that aimed to trace the hierarchical processing network for speech comprehension within the left and right hemisphere with a particular focus on the temporal lobe and the ventral stream. As hypothesized, the results demonstrate a bilateral involvement of the temporal lobes in the processing of speech signals. However, an increasing leftward asymmetry was detected from auditory-phonetic to lexico-semantic processing and along the posterior-anterior axis, thus forming a "lateralization" gradient. This increasing leftward lateralization was particularly evident for the left superior temporal sulcus and more anterior parts of the temporal lobe.

Mapping a lateralization gradient within the ventral stream for auditory speech perception

PubMed Central

Specht, Karsten

2013-01-01

Recent models on speech perception propose a dual-stream processing network, with a dorsal stream, extending from the posterior temporal lobe of the left hemisphere through inferior parietal areas into the left inferior frontal gyrus, and a ventral stream that is assumed to originate in the primary auditory cortex in the upper posterior part of the temporal lobe and to extend toward the anterior part of the temporal lobe, where it may connect to the ventral part of the inferior frontal gyrus. This article describes and reviews the results from a series of complementary functional magnetic resonance imaging studies that aimed to trace the hierarchical processing network for speech comprehension within the left and right hemisphere with a particular focus on the temporal lobe and the ventral stream. As hypothesized, the results demonstrate a bilateral involvement of the temporal lobes in the processing of speech signals. However, an increasing leftward asymmetry was detected from auditory–phonetic to lexico-semantic processing and along the posterior–anterior axis, thus forming a “lateralization” gradient. This increasing leftward lateralization was particularly evident for the left superior temporal sulcus and more anterior parts of the temporal lobe. PMID:24106470

Floodplain geomorphic processes and environmental impacts of human alteration along coastal plain rivers, USA

USGS Publications Warehouse

Hupp, C.R.; Pierce, Aaron R.; Noe, G.B.

2009-01-01

Human alterations along stream channels and within catchments have affected fluvial geomorphic processes worldwide. Typically these alterations reduce the ecosystem services that functioning floodplains provide; in this paper we are concerned with the sediment and associated material trapping service. Similarly, these alterations may negatively impact the natural ecology of floodplains through reductions in suitable habitats, biodiversity, and nutrient cycling. Dams, stream channelization, and levee/canal construction are common human alterations along Coastal Plain fluvial systems. We use three case studies to illustrate these alterations and their impacts on floodplain geomorphic and ecological processes. They include: 1) dams along the lower Roanoke River, North Carolina, 2) stream channelization in west Tennessee, and 3) multiple impacts including canal and artificial levee construction in the central Atchafalaya Basin, Louisiana. Human alterations typically shift affected streams away from natural dynamic equilibrium where net sediment deposition is, approximately, in balance with net erosion. Identification and understanding of critical fluvial parameters (e.g., stream gradient, grain-size, and hydrography) and spatial and temporal sediment deposition/erosion process trajectories should facilitate management efforts to retain and/or regain important ecosystem services. ?? 2009, The Society of Wetland Scientists.

Emotion processing in the visual brain: a MEG analysis.

PubMed

Peyk, Peter; Schupp, Harald T; Elbert, Thomas; Junghöfer, Markus

2008-06-01

Recent functional magnetic resonance imaging (fMRI) and event-related brain potential (ERP) studies provide empirical support for the notion that emotional cues guide selective attention. Extending this line of research, whole head magneto-encephalogram (MEG) was measured while participants viewed in separate experimental blocks a continuous stream of either pleasant and neutral or unpleasant and neutral pictures, presented for 330 ms each. Event-related magnetic fields (ERF) were analyzed after intersubject sensor coregistration, complemented by minimum norm estimates (MNE) to explore neural generator sources. Both streams of analysis converge by demonstrating the selective emotion processing in an early (120-170 ms) and a late time interval (220-310 ms). ERF analysis revealed that the polarity of the emotion difference fields was reversed across early and late intervals suggesting distinct patterns of activation in the visual processing stream. Source analysis revealed the amplified processing of emotional pictures in visual processing areas with more pronounced occipito-parieto-temporal activation in the early time interval, and a stronger engagement of more anterior, temporal, regions in the later interval. Confirming previous ERP studies showing facilitated emotion processing, the present data suggest that MEG provides a complementary look at the spread of activation in the visual processing stream.

Colour discrimination and categorisation in Williams syndrome.

PubMed

Farran, Emily K; Cranwell, Matthew B; Alvarez, James; Franklin, Anna

2013-10-01

Individuals with Williams syndrome (WS) present with impaired functioning of the dorsal visual stream relative to the ventral visual stream. As such, little attention has been given to ventral stream functions in WS. We investigated colour processing, a predominantly ventral stream function, for the first time in nineteen individuals with Williams syndrome. Colour discrimination was assessed using the Farnsworth-Munsell 100 hue test. Colour categorisation was assessed using a match-to-sample test and a colour naming task. A visual search task was also included as a measure of sensitivity to the size of perceptual colour difference. Results showed that individuals with WS have reduced colour discrimination relative to typically developing participants matched for chronological age; performance was commensurate with a typically developing group matched for non-verbal ability. In contrast, categorisation was typical in WS, although there was some evidence that sensitivity to the size of perceptual colour differences was reduced in this group. Copyright © 2013 Elsevier Ltd. All rights reserved.

Columnar Segregation of Magnocellular and Parvocellular Streams in Human Extrastriate Cortex

PubMed Central

2017-01-01

Magnocellular versus parvocellular (M-P) streams are fundamental to the organization of macaque visual cortex. Segregated, paired M-P streams extend from retina through LGN into V1. The M stream extends further into area V5/MT, and parts of V2. However, elsewhere in visual cortex, it remains unclear whether M-P-derived information (1) becomes intermixed or (2) remains segregated in M-P-dominated columns and neurons. Here we tested whether M-P streams exist in extrastriate cortical columns, in 8 human subjects (4 female). We acquired high-resolution fMRI at high field (7T), testing for M- and P-influenced columns within each of four cortical areas (V2, V3, V3A, and V4), based on known functional distinctions in M-P streams in macaque: (1) color versus luminance, (2) binocular disparity, (3) luminance contrast sensitivity, (4) peak spatial frequency, and (5) color/spatial interactions. Additional measurements of resting state activity (eyes closed) tested for segregated functional connections between these columns. We found M- and P-like functions and connections within and between segregated cortical columns in V2, V3, and (in most experiments) area V4. Area V3A was dominated by the M stream, without significant influence from the P stream. These results suggest that M-P streams exist, and extend through, specific columns in early/middle stages of human extrastriate cortex. SIGNIFICANCE STATEMENT The magnocellular and parvocellular (M-P) streams are fundamental components of primate visual cortical organization. These streams segregate both anatomical and functional properties in parallel, from retina through primary visual cortex. However, in most higher-order cortical sites, it is unknown whether such M-P streams exist and/or what form those streams would take. Moreover, it is unknown whether M-P streams exist in human cortex. Here, fMRI evidence measured at high field (7T) and high resolution revealed segregated M-P streams in four areas of human extrastriate cortex. These results suggest that M-P information is processed in segregated parallel channels throughout much of human visual cortex; the M-P streams are more than a convenient sorting property in earlier stages of the visual system. PMID:28724749

Alteration of stream temperature by natural and artificial beaver dams.

PubMed

Weber, Nicholas; Bouwes, Nicolaas; Pollock, Michael M; Volk, Carol; Wheaton, Joseph M; Wathen, Gus; Wirtz, Jacob; Jordan, Chris E

2017-01-01

Beaver are an integral component of hydrologic, geomorphic, and biotic processes within North American stream systems, and their propensity to build dams alters stream and riparian structure and function to the benefit of many aquatic and terrestrial species. Recognizing this, beaver relocation efforts and/or application of structures designed to mimic the function of beaver dams are increasingly being utilized as effective and cost-efficient stream and riparian restoration approaches. Despite these verities, the notion that beaver dams negatively impact stream habitat remains common, specifically the assumption that beaver dams increase stream temperatures during summer to the detriment of sensitive biota such as salmonids. In this study, we tracked beaver dam distributions and monitored water temperature throughout 34 km of stream for an eight-year period between 2007 and 2014. During this time the number of natural beaver dams within the study area increased by an order of magnitude, and an additional 4 km of stream were subject to a restoration manipulation that included installing a high-density of Beaver Dam Analog (BDA) structures designed to mimic the function of natural beaver dams. Our observations reveal several mechanisms by which beaver dam development may influence stream temperature regimes; including longitudinal buffering of diel summer temperature extrema at the reach scale due to increased surface water storage, and creation of cool-water channel scale temperature refugia through enhanced groundwater-surface water connectivity. Our results suggest that creation of natural and/or artificial beaver dams could be used to mitigate the impact of human induced thermal degradation that may threaten sensitive species.

Alteration of stream temperature by natural and artificial beaver dams

PubMed Central

Bouwes, Nicolaas; Pollock, Michael M.; Volk, Carol; Wheaton, Joseph M.; Wathen, Gus; Wirtz, Jacob; Jordan, Chris E.

2017-01-01

Beaver are an integral component of hydrologic, geomorphic, and biotic processes within North American stream systems, and their propensity to build dams alters stream and riparian structure and function to the benefit of many aquatic and terrestrial species. Recognizing this, beaver relocation efforts and/or application of structures designed to mimic the function of beaver dams are increasingly being utilized as effective and cost-efficient stream and riparian restoration approaches. Despite these verities, the notion that beaver dams negatively impact stream habitat remains common, specifically the assumption that beaver dams increase stream temperatures during summer to the detriment of sensitive biota such as salmonids. In this study, we tracked beaver dam distributions and monitored water temperature throughout 34 km of stream for an eight-year period between 2007 and 2014. During this time the number of natural beaver dams within the study area increased by an order of magnitude, and an additional 4 km of stream were subject to a restoration manipulation that included installing a high-density of Beaver Dam Analog (BDA) structures designed to mimic the function of natural beaver dams. Our observations reveal several mechanisms by which beaver dam development may influence stream temperature regimes; including longitudinal buffering of diel summer temperature extrema at the reach scale due to increased surface water storage, and creation of cool—water channel scale temperature refugia through enhanced groundwater—surface water connectivity. Our results suggest that creation of natural and/or artificial beaver dams could be used to mitigate the impact of human induced thermal degradation that may threaten sensitive species. PMID:28520714

The use of wooden sticks to assess stream ecosystem functioning: comparison with leaf breakdown rates.

PubMed

Arroita, Maite; Aristi, Ibon; Flores, Lorea; Larrañaga, Aitor; Díez, Joserra; Mora, Juanita; Romaní, Anna M; Elosegi, Arturo

2012-12-01

Breakdown of organic matter is a key process in streams and rivers, and thus, it has potential to assess functional impairment of river ecosystems. Because the litter-bag method commonly used to measure leaf breakdown is time consuming and expensive, several authors proposed to measure breakdown of wooden sticks instead. Nevertheless, currently there is little information on the performance of wooden sticks versus that of leaves. We compared the breakdown of tongue depressors made of untreated poplar wood, to that of six common leaf species in two large streams in the Basque Country (northern Spain), one polluted and the other unpolluted. Breakdown rates ranged from 0.0011 to 0.0120 day(-1), and were significantly lower in the polluted stream. Wooden sticks performed very similarly to leaves, but were less affected by flood-induced physical abrasion. The ranking of the materials according to their breakdown rate was consistent, irrespective of the stream. The experiments with leaves were 10 times more costly for breakdown rate, 4 times if we include the rest of the variables measured. Therefore wooden sticks offer a promising tool to assess river ecosystem functioning, although more research is necessary to define the thresholds for ecosystem functional impairment. Copyright © 2012 Elsevier B.V. All rights reserved.

Perspectives on ecological research at the Outdoor StreamLab, a field-scale experimental stream

NASA Astrophysics Data System (ADS)

Merten, E. C.; Dieterman, D.; Kramarczuk, K.; Lightbody, A.; Orr, C. H.; Wellnitz, T.

2009-12-01

Artificial streams hold great promise for examining ecological processes. They lend themselves to manipulations of discharge, sediment load, water chemistry, and other parameters difficult or impossible to control in natural streams. However, artificial streams also have important limitations. In this presentation we describe insights gained from several ecological studies conducted at the St. Anthony Falls Laboratory’s Outdoor StreamLab, including, 1) short-term turbidity exposure effects on fish health, 2) macroinvertebrate grazing rates on periphyton as a function of velocity, 3) rates of macroinvertebrate colonization as related to velocity, and 4) fine-scale correlations of periphytic biomass with hydraulic conditions. Several lessons emerge from these initial attempts at ecological research in the Outdoor StreamLab. We have learned that the size, flow rate, substrate, water chemistry, and available colonization population of the artificial stream limit the kinds of organisms and types of ecological processes that can be examined and the types of experiments that can be run. We suggest that short-term biotic responses are best for study in a system of this type, and note that constant experiment maintenance is essential. Operating artificial streams to meet the needs of multiple researchers also presents challenges of scheduling, coordination, and conflict resolution. Although ecological research in artificial streams has considerable potential, the planning required is no less than that of traditional field studies.

When does diversity matter? Species functional diversity and ecosystem functioning across habitats and seasons in a field experiment.

PubMed

Frainer, André; McKie, Brendan G; Malmqvist, Björn

2014-03-01

Despite ample experimental evidence indicating that biodiversity might be an important driver of ecosystem processes, its role in the functioning of real ecosystems remains unclear. In particular, the understanding of which aspects of biodiversity are most important for ecosystem functioning, their importance relative to other biotic and abiotic drivers, and the circumstances under which biodiversity is most likely to influence functioning in nature, is limited. We conducted a field study that focussed on a guild of insect detritivores in streams, in which we quantified variation in the process of leaf decomposition across two habitats (riffles and pools) and two seasons (autumn and spring). The study was conducted in six streams, and the same locations were sampled in the two seasons. With the aid of structural equations modelling, we assessed spatiotemporal variation in the roles of three key biotic drivers in this process: functional diversity, quantified based on a species trait matrix, consumer density and biomass. Our models also accounted for variability related to different litter resources, and other sources of biotic and abiotic variability among streams. All three of our focal biotic drivers influenced leaf decomposition, but none was important in all habitats and seasons. Functional diversity had contrasting effects on decomposition between habitats and seasons. A positive relationship was observed in pool habitats in spring, associated with high trait dispersion, whereas a negative relationship was observed in riffle habitats during autumn. Our results demonstrate that functional biodiversity can be as significant for functioning in natural ecosystems as other important biotic drivers. In particular, variation in the role of functional diversity between seasons highlights the importance of fluctuations in the relative abundances of traits for ecosystem process rates in real ecosystems. © 2013 The Authors. Journal of Animal Ecology © 2013 British Ecological Society.

An ecohydraulic view on stream resilience and ecosystem functioning - what can science teach management?

NASA Astrophysics Data System (ADS)

Battin, Tom J.; Dzubakova, Katharina; Boodoo, Kyle; Ulseth, Amber

2017-04-01

Streams and rivers are increasingly exposed to environmental change across various spatial and temporal scales. Consequently, ecosystem health and integrity are becoming compromised. Most management strategies designed to recover and maintain stream ecosystem health involve engineering measures of geomorphology. The success of such engineering measures relies on a thorough understanding of the underlying physical, chemical and biological process coupling across scales. First, we present results from experimental work unraveling the relevance of streambed heterogeneity for the resilience of phototrophic biofilms. This is critical as phototrophic biofilms are key for nutrient removal and hence for keeping the water clean. These biofilms are also the machinery of primary production and related carbon fluxes in stream ecosystems. Next, we show how climate change may affect primary production, including CO2, in streams and the networks they form. In fact, streams are now recognized as major sources of CO2 to the atmosphere and contributors to the global carbon cycle. Despite this, we do not yet understand how geomorphological features, themselves continuously reworked by hydrology and sedimentary dynamics, affect CO2 fluxes in streams. We show that gravel bars, clearly conspicuous geomorphological features, are hotspots of CO2 fluxes compared to the streamwater itself. This has major implications for carbon cycling and stream ecosystem functioning. Finally, we discuss what stream management could learn from ecohydraulic insights from young scientists doing excellent basic research.

Side Streams of Plant Food Processing As a Source of Valuable Compounds: Selected Examples.

PubMed

Schieber, Andreas

2017-02-28

Industrial processing of plant-derived raw materials generates enormous amounts of by-products. On one hand, these by-products constitute a serious disposal issue because they often emerge seasonally and are prone to microbial decay. On the other hand, they are an abundant source of valuable compounds, in particular secondary plant metabolites and cell wall materials, which may be recovered and used to functionalize foods and replace synthetic additives with ingredients of natural origin. This review covers 150 references and presents select studies performed between 2001 and 2016 on the recovery, characterization, and application of valuable constituents from grape pomace, apple pomace, potato peels, tomato pomace, carrot pomace, onion peels, by-products of citrus, mango, banana, and pineapple processing, side streams of olive oil production, and cereal by-products. The criteria used were economic importance, amounts generated, relevance of side streams as a source of valuable compounds, and reviews already published. Despite a plethora of studies carried out on the utilization of side streams, relatively few processes have yet found industrial application.

Geomorphic effectiveness of long profile shape and role of inherent geological controls, Ganga River Basin, India

NASA Astrophysics Data System (ADS)

Sonam, Sonam; Jain, Vikrant

2017-04-01

River long profile is one of the fundamental geomorphic parameters which provides a platform to study interaction of geological and geomorphic processes at different time scales. Long profile shape is governed by geological processes at 10 ^ 5 - 10 ^ 6 years' time scale and it controls the modern day (10 ^ 0 - 10 ^ 1 years' time scale) fluvial processes by controlling the spatial variability of channel slope. Identification of an appropriate model for river long profile may provide a tool to analyse the quantitative relationship between basin geology, profile shape and its geomorphic effectiveness. A systematic analysis of long profiles has been carried for the Himalayan tributaries of the Ganga River basin. Long profile shape and stream power distribution pattern is derived using SRTM DEM data (90 m spatial resolution). Peak discharge data from 34 stations is used for hydrological analysis. Lithological variability and major thrusts are marked along the river long profile. The best fit of long profile is analysed for power, logarithmic and exponential function. Second order exponential function provides the best representation of long profiles. The second order exponential equation is Z = K1*exp(-β1*L) + K2*exp(-β2*L), where Z is elevation of channel long profile, L is the length, K and β are coefficients of the exponential function. K1 and K2 are the proportion of elevation change of the long profile represented by β1 (fast) and β2 (slow) decay coefficients of the river long profile. Different values of coefficients express the variability in long profile shapes and is related with the litho-tectonic variability of the study area. Channel slope of long profile is estimated taking the derivative of exponential function. Stream power distribution pattern along long profile is estimated by superimposing the discharge and long profile slope. Sensitivity analysis of stream power distribution with decay coefficients of the second order exponential equation is evaluated for a range of coefficient values. Our analysis suggests that the amplitude of stream power peak value is dependent on K1, the proportion of elevation change coming under the fast decay exponent and the location of stream power peak is dependent of the long profile decay coefficient (β1). Different long profile shapes owing to litho-tectonic variability across the Himalayas are responsible for spatial variability of stream power distribution pattern. Most of the stream power peaks lie in the Higher Himalaya. In general, eastern rivers have higher stream power in hinterland area and low stream power in the alluvial plains. This is responsible for, 1) higher erosion rate and sediment supply in hinterland of eastern rivers, 2) the incised and stable nature of channels in the western alluvial plains and 3) aggrading channels with dynamic nature in the eastern alluvial plains. Our study shows that the spatial variability of litho-units defines the coefficients of long profile function which in turn controls the position and magnitude of stream power maxima and hence the geomorphic variability in a fluvial system.

SOMKE: kernel density estimation over data streams by sequences of self-organizing maps.

PubMed

Cao, Yuan; He, Haibo; Man, Hong

2012-08-01

In this paper, we propose a novel method SOMKE, for kernel density estimation (KDE) over data streams based on sequences of self-organizing map (SOM). In many stream data mining applications, the traditional KDE methods are infeasible because of the high computational cost, processing time, and memory requirement. To reduce the time and space complexity, we propose a SOM structure in this paper to obtain well-defined data clusters to estimate the underlying probability distributions of incoming data streams. The main idea of this paper is to build a series of SOMs over the data streams via two operations, that is, creating and merging the SOM sequences. The creation phase produces the SOM sequence entries for windows of the data, which obtains clustering information of the incoming data streams. The size of the SOM sequences can be further reduced by combining the consecutive entries in the sequence based on the measure of Kullback-Leibler divergence. Finally, the probability density functions over arbitrary time periods along the data streams can be estimated using such SOM sequences. We compare SOMKE with two other KDE methods for data streams, the M-kernel approach and the cluster kernel approach, in terms of accuracy and processing time for various stationary data streams. Furthermore, we also investigate the use of SOMKE over nonstationary (evolving) data streams, including a synthetic nonstationary data stream, a real-world financial data stream and a group of network traffic data streams. The simulation results illustrate the effectiveness and efficiency of the proposed approach.

Face and location processing in children with early unilateral brain injury.

PubMed

Paul, Brianna; Appelbaum, Mark; Carapetian, Stephanie; Hesselink, John; Nass, Ruth; Trauner, Doris; Stiles, Joan

2014-07-01

Human visuospatial functions are commonly divided into those dependent on the ventral visual stream (ventral occipitotemporal regions), which allows for processing the 'what' of an object, and the dorsal visual stream (dorsal occipitoparietal regions), which allows for processing 'where' an object is in space. Information about the development of each of the two streams has been accumulating, but very little is known about the effects of injury, particularly very early injury, on this developmental process. Using a set of computerized dorsal and ventral stream tasks matched for stimuli, required response, and difficulty (for typically-developing individuals), we sought to compare the differential effects of injury to the two systems by examining performance in individuals with perinatal brain injury (PBI), who present with selective deficits in visuospatial processing from a young age. Thirty participants (mean=15.1 years) with early unilateral brain injury (15 right hemisphere PBI, 15 left hemisphere PBI) and 16 matched controls participated. On our tasks children with PBI performed more poorly than controls (lower accuracy and longer response times), and this was particularly prominent for the ventral stream task. Lateralization of PBI was also a factor, as the dorsal stream task did not seem to be associated with lateralized deficits, with both PBI groups showing only subtle decrements in performance, while the ventral stream task elicited deficits from RPBI children that do not appear to improve with age. Our findings suggest that early injury results in lesion-specific visuospatial deficits that persist into adolescence. Further, as the stimuli used in our ventral stream task were faces, our findings are consistent with what is known about the neural systems for face processing, namely, that they are established relatively early, follow a comparatively rapid developmental trajectory (conferring a vulnerability to early insult), and are biased toward the right hemisphere. Copyright © 2014 Elsevier Inc. All rights reserved.

Endogenous Delta/Theta Sound-Brain Phase Entrainment Accelerates the Buildup of Auditory Streaming.

PubMed

Riecke, Lars; Sack, Alexander T; Schroeder, Charles E

2015-12-21

In many natural listening situations, meaningful sounds (e.g., speech) fluctuate in slow rhythms among other sounds. When a slow rhythmic auditory stream is selectively attended, endogenous delta (1‒4 Hz) oscillations in auditory cortex may shift their timing so that higher-excitability neuronal phases become aligned with salient events in that stream [1, 2]. As a consequence of this stream-brain phase entrainment [3], these events are processed and perceived more readily than temporally non-overlapping events [4-11], essentially enhancing the neural segregation between the attended stream and temporally noncoherent streams [12]. Stream-brain phase entrainment is robust to acoustic interference [13-20] provided that target stream-evoked rhythmic activity can be segregated from noncoherent activity evoked by other sounds [21], a process that usually builds up over time [22-27]. However, it has remained unclear whether stream-brain phase entrainment functionally contributes to this buildup of rhythmic streams or whether it is merely an epiphenomenon of it. Here, we addressed this issue directly by experimentally manipulating endogenous stream-brain phase entrainment in human auditory cortex with non-invasive transcranial alternating current stimulation (TACS) [28-30]. We assessed the consequences of these manipulations on the perceptual buildup of the target stream (the time required to recognize its presence in a noisy background), using behavioral measures in 20 healthy listeners performing a naturalistic listening task. Experimentally induced cyclic 4-Hz variations in stream-brain phase entrainment reliably caused a cyclic 4-Hz pattern in perceptual buildup time. Our findings demonstrate that strong endogenous delta/theta stream-brain phase entrainment accelerates the perceptual emergence of task-relevant rhythmic streams in noisy environments. Copyright © 2015 Elsevier Ltd. All rights reserved.

Combined effects of hydrologic alteration and cyprinid fish in mediating biogeochemical processes in a Mediterranean stream.

PubMed

Rubio-Gracia, Francesc; Almeida, David; Bonet, Berta; Casals, Frederic; Espinosa, Carmen; Flecker, Alexander S; García-Berthou, Emili; Martí, Eugènia; Tuulaikhuu, Baigal-Amar; Vila-Gispert, Anna; Zamora, Lluis; Guasch, Helena

2017-12-01

Flow regimes are important drivers of both stream community and biogeochemical processes. However, the interplay between community and biogeochemical responses under different flow regimes in streams is less understood. In this study, we investigated the structural and functional responses of periphyton and macroinvertebrates to different densities of the Mediterranean barbel (Barbus meridionalis, Cyprinidae) in two stream reaches differing in flow regime. The study was conducted in Llémena Stream, a small calcareous Mediterranean stream with high nutrient levels. We selected a reach with permanent flow (permanent reach) and another subjected to flow regulation (regulated reach) with periods of flow intermittency. At each reach, we used in situ cages to generate 3 levels of fish density. Cages with 10 barbels were used to simulate high fish density (>7indm -2 ); cages with open sides were used as controls (i.e. exposed to actual fish densities of each stream reach) thus having low fish density; and those with no fish were used to simulate the disappearance of fish that occurs with stream drying. Differences in fish density did not cause significant changes in periphyton biomass and macroinvertebrate density. However, phosphate uptake by periphyton was enhanced in treatments lacking fish in the regulated reach with intermittent flow but not in the permanent reach, suggesting that hydrologic alteration hampers the ability of biotic communities to compensate for the absence of fish. This study indicates that fish density can mediate the effects of anthropogenic alterations such as flow intermittence derived from hydrologic regulation on stream benthic communities and associated biogeochemical processes, at least in eutrophic streams. Copyright © 2017. Published by Elsevier B.V.

From genes to brain development to phenotypic behavior: "dorsal-stream vulnerability" in relation to spatial cognition, attention, and planning of actions in Williams syndrome (WS) and other developmental disorders.

PubMed

Atkinson, Janette; Braddick, Oliver

2011-01-01

Visual information is believed to be processed through two distinct, yet interacting cortical streams. The ventral stream performs the computations needed for recognition of objects and faces ("what" and "who"?) and the dorsal stream the computations for registering spatial relationships and for controlling visually guided actions ("where" and "how"?). We initially proposed a model of spatial deficits in Williams syndrome (WS) in which visual abilities subserved by the ventral stream, such as face recognition, are relatively well developed (although not necessarily in exactly the same way as in typical development), whereas dorsal-stream functions, such as visuospatial actions, are markedly impaired. Since these initial findings in WS, deficits of motion coherence sensitivity, a dorsal-stream function has been found in other genetic disorders such as Fragile X and autism, and as a consequence of perinatal events (in hemiplegia, perinatal brain anomalies following very premature birth), leading to the proposal of a general "dorsal-stream vulnerability" in many different conditions of abnormal human development. In addition, dorsal-stream systems provide information used in tasks of visuospatial memory and locomotor planning, and these systems are closely coupled to networks for attentional control. We and several other research groups have previously shown deficits of frontal and parietal lobe function in WS individuals for specific attention tasks [e.g., Atkinson, J., Braddick, O., Anker, S., Curran, W., & Andrew, R. (2003). Neurobiological models of visuospatial cognition in children with Williams Syndrome: Measures of dorsal-stream and frontal function. Developmental Neuropsychology, 23(1/2), 141-174.]. We have used the Test of Everyday Attention for Children (TEA-Ch) which aims to attempt to separate components of attention with distinct brain networks (selective attention, sustained attention, and attention control-executive function) testing a group of older children with WS, but this test battery is too demanding for many children and adults with WS. Consequently, we have devised a new set of tests of attention, the Early Childhood Attention Battery (ECAB). This uses similar principles to the TEA-Ch, but adapted for mental ages younger than 6 years. The ECAB shows a distinctive attention profile for WS individuals relative to their overall cognitive development, with relative strength in tasks of sustained attention and poorer performance on tasks of selective attention and executive control. These profiles, and the characteristic developmental courses, also show differences between children with Down's syndrome and WS. This chapter briefly reviews new research findings on WS in these areas, relating the development of brain systems in WS to evidence from neuroimaging in typically developing infants, children born very preterm, and normal adults. The hypothesis of "dorsal-stream(s) vulnerability" which will be discussed includes a number of interlinked brain networks, subserving not only global visual processing and formulation of visuomotor actions but interlinked networks of attention. Copyright © 2011 Elsevier B.V. All rights reserved.

Are big basins just the sum of small catchments?

USGS Publications Warehouse

Shaman, J.; Stieglitz, M.; Burns, D.

2004-01-01

Many challenges remain in extending our understanding of how hydrologic processes within small catchments scale to larger river basins. In this study we examine how low-flow runoff varies as a function of basin scale at 11 catchments, many of which are nested, in the 176 km2 Neversink River watershed in the Catskill Mountains of New York. Topography, vegetation, soil and bedrock structure are similar across this river basin, and previous research has demonstrated the importance of deep groundwater springs for maintaining low-flow stream discharge at small scales in the basin. Therefore, we hypothesized that deep groundwater would contribute an increasing amount to low-flow discharge as basin scale increased, resulting in increased runoff. Instead, we find that, above a critical basin size of 8 to 21 km2, low-flow runoff is similar within the Neversink watershed. These findings are broadly consistent with those of a previous study that examined stream chemistry as a function of basin scale for this watershed. However, we find physical evidence of self-similarity among basins greater than 8 km2, whereas the previous study found gradual changes in stream chemistry among basins greater than 3 km 2. We believe that a better understanding of self-similarity and the subsurface flow processes that affect stream runoff will be attained through simultaneous consideration of both chemical and physical evidence. We also suggest that similar analyses of stream runoff in other basins that represent a range of spatial scales, geomorphologies and climate conditions will further elucidate the issue of scaling of hydrologic processes. Copyright ?? 2004 John Wiley & Sons, Ltd.

Ecological Exposure Research: Water

EPA Pesticide Factsheets

Overview of ecological exposure water research, including invasive species, Functional Process Zones (FPZs), biomarkers, pharmaceuticals in water, headwater streams, DNA barcoding, wetland ecosystem services, and sediment remediation.

Testing ecological tradeoffs of a new tool for removing fine sediment in a spring-fed stream

USGS Publications Warehouse

Sepulveda, Adam; Sechrist, Juddson D.; Marczak, Laurie B

2014-01-01

Excessive fine sediment is a focus of stream restoration work because it can impair the structure and function of streams, but few methods exist for removing sediment in spring-fed streams. We tested a novel method of sediment removal with the potential to have minimal adverse effects on the biological community during the restoration process. The Sand Wand system, a dredgeless vacuum developed by Streamside Technologies, was used to experimentally remove fine sediment from Kackley Springs, a spring creek in southeastern Idaho. We assessed the effects of the Sand Wand on stream physical habitat and macroinvertebrate composition for up to 60 days after the treatment. We documented changes in multiple habitat variables, including stream depth, median particle size, and the frequency of embedded substrate in stream reaches that were treated with the Sand Wand. We also found that macroinvertebrate composition was altered even though common macroinvertebrate metrics changed little after the treatment. Our results suggest that the Sand Wand was effective at removing fine sediments in Kackley Springs and did minimal harm to macroinvertebrate function, but the Sand Wand was not ultimately effective in improving substrate composition to desired conditions. Additional restoration techniques are still needed to decrease the amount of fine sediment.

Increasing floodplain connectivity through urban stream restoration increases nutrient and sediment retention

USGS Publications Warehouse

McMillan, Sara K.; Noe, Gregory

2017-01-01

Stream restoration practices frequently aim to increase connectivity between the stream channel and its floodplain to improve channel stability and enhance water quality through sediment trapping and nutrient retention. To measure the effectiveness of restoration and to understand the drivers of these functional responses, we monitored five restored urban streams that represent a range of channel morphology and restoration ages. High and low elevation floodplain plots were established in triplicate in each stream to capture variation in floodplain connectivity. We measured ecosystem geomorphic and soil attributes, sediment and nutrient loading, and rates of soil nutrient biogeochemistry processes (denitrification; N and P mineralization) then used boosted regression trees (BRT) to identify controls on sedimentation and nutrient processing. Local channel and floodplain morphology and position within the river network controlled connectivity with increased sedimentation at sites downstream of impaired reaches and at floodplain plots near the stream channel and at low elevations. We observed that nitrogen loading (both dissolved and particulate) was positively correlated with denitrification and N mineralization and dissolved phosphate loading positively influenced P mineralization; however, none of these input rates or transformations differed between floodplain elevation categories. Instead, continuous gradients of connectivity were observed rather than categorical shifts between inset and high floodplains. Organic matter and nutrient content in floodplain soils increased with the time since restoration, which highlights the importance of recovery time after construction that is needed for restored systems to increase ecosystem functions. Our results highlight the importance of restoring floodplains downstream of sources of impairment and building them at lower elevations so they flood frequently, not just during bankfull events. This integrated approach has the greatest potential for increasing trapping of sediment, nutrients, and associated pollutants in restored streams and thereby improving water quality in urban watersheds.

Language Learning Variability within the Dorsal and Ventral Streams as a Cue for Compensatory Mechanisms in Aphasia Recovery

PubMed Central

López-Barroso, Diana; de Diego-Balaguer, Ruth

2017-01-01

Dorsal and ventral pathways connecting perisylvian language areas have been shown to be functionally and anatomically segregated. Whereas the dorsal pathway integrates the sensory-motor information required for verbal repetition, the ventral pathway has classically been associated with semantic processes. The great individual differences characterizing language learning through life partly correlate with brain structure and function within these dorsal and ventral language networks. Variability and plasticity within these networks also underlie inter-individual differences in the recovery of linguistic abilities in aphasia. Despite the division of labor of the dorsal and ventral streams, studies in healthy individuals have shown how the interaction of them and the redundancy in the areas they connect allow for compensatory strategies in functions that are usually segregated. In this mini-review we highlight the need to examine compensatory mechanisms between streams in healthy individuals as a helpful guide to choosing the most appropriate rehabilitation strategies, using spared functions and targeting preserved compensatory networks for brain plasticity. PMID:29021751

Sources, transformations, and hydrological processes that control stream nitrate and dissolved organic matter concentrations during snowmelt in an upland forest

USGS Publications Warehouse

Sebestyen, Stephen D.; Boyer, Elizabeth W.; Shanley, James B.; Kendall, Carol; Doctor, Daniel H.; Aiken, George R.; Ohte, Nobuhito

2008-01-01

We explored catchment processes that control stream nutrient concentrations at an upland forest in northeastern Vermont, USA, where inputs of nitrogen via atmospheric deposition are among the highest in the nation and affect ecosystem functioning. We traced sources of water, nitrate, and dissolved organic matter (DOM) using stream water samples collected at high frequency during spring snowmelt. Hydrochemistry, isotopic tracers, and end‐member mixing analyses suggested the timing, sources, and source areas from which water and nutrients entered the stream. Although stream‐dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) both originated from leaching of soluble organic matter, flushing responses between these two DOM components varied because of dynamic shifts of hydrological flow paths and sources that supply the highest concentrations of DOC and DON. High concentrations of stream water nitrate originated from atmospheric sources as well as nitrified sources from catchment soils. We detected nitrification in surficial soils during late snowmelt which affected the nitrate supply that was available to be transported to streams. However, isotopic tracers showed that the majority of nitrate in upslope surficial soil waters after the onset of snowmelt originated from atmospheric sources. A fraction of the atmospheric nitrogen was directly delivered to the stream, and this finding highlights the importance of quick flow pathways during snowmelt events. These findings indicate that interactions among sources, transformations, and hydrologic transport processes must be deciphered to understand why concentrations vary over time and over space as well as to elucidate the direct effects of human activities on nutrient dynamics in upland forest streams.

Factors influencing wood mobilization in Minnesota streams

USGS Publications Warehouse

Merten, Eric; Finlay, Jacques; Johnson, Lucinda; Newman, Raymond; Stefan, Heinz; Vondracek, Bruce C.

2010-01-01

Natural pieces of wood provide a variety of ecosystem functions in streams including habitat, organic matter retention, increased hyporheic exchange and transient storage, and enhanced hydraulic and geomorphic heterogeneity. Wood mobilization is a critical process in determining the residence time of wood. We documented the characteristics and locations of 865 natural wood pieces (>0.05 m in diameter for a portion >1 m in length) in nine streams along the north shore of Lake Superior in Minnesota. We determined the locations of the pieces again after an overbank stormflow event to determine the factors that influenced mobilization of stationary wood pieces in natural streams. Seven of 11 potential predictor variables were identified with multiple logistic regression as significant to mobilization: burial, effective depth, ratio of piece length to effective stream width (length ratio), bracing, rootwad presence, downstream force ratio, and draft ratio. The final model (P< 0.001, r2 = 0.39) indicated that wood mobilization under natural conditions is a complex function of both mechanical factors (burial, length ratio, bracing, rootwad presence, draft ratio) and hydraulic factors (effective depth, downstream force ratio). If stable pieces are a goal for stream management then features such as partial burial, low effective depth, high length relative to channel width, bracing against other objects (e.g., stream banks, trees, rocks, or larger wood pieces), and rootwads are desirable. Using the model equation from this study, stewards of natural resources can better manage in-stream wood for the benefit of stream ecosystems.

A Review on Data Stream Classification

NASA Astrophysics Data System (ADS)

Haneen, A. A.; Noraziah, A.; Wahab, Mohd Helmy Abd

2018-05-01

At this present time, the significance of data streams cannot be denied as many researchers have placed their focus on the research areas of databases, statistics, and computer science. In fact, data streams refer to some data points sequences that are found in order with the potential to be non-binding, which is generated from the process of generating information in a manner that is not stationary. As such the typical tasks of searching data have been linked to streams of data that are inclusive of clustering, classification, and repeated mining of pattern. This paper presents several data stream clustering approaches, which are based on density, besides attempting to comprehend the function of the related algorithms; both semi-supervised and active learning, along with reviews of a number of recent studies.

Waste streams in a crewed space habitat

NASA Technical Reports Server (NTRS)

Wydeven, T.; Golub, M. A.

1991-01-01

A judicious compilation of generation rates and chemical compositions of potential waste feed streams in a typical crewed space habitat was made in connection with the waste-management aspect of NASA's Physical/Chemical Closed-Loop Life Support Program. Waste composition definitions are needed for the design of waste-processing technologies involved in closing major life support functions in future long-duration human space missions. Tables of data for the constituents and chemical formulas of the following waste streams are presented and discussed: human urine, feces, hygiene (laundry and shower) water, cleansing agents, trash, humidity condensate, dried sweat, and trace contaminants. Tables of data on dust generation and pH values of the different waste streams are also presented and discussed.

Geomorphic effectiveness of a long profile shape and the role of inherent geological controls in the Himalayan hinterland area of the Ganga River basin, India

NASA Astrophysics Data System (ADS)

Sonam; Jain, Vikrant

2018-03-01

Long profiles of rivers provide a platform to analyse interaction between geological and geomorphic processes operating at different time scales. Identification of an appropriate model for river long profile becomes important in order to establish a quantitative relationship between the profile shape, its geomorphic effectiveness, and inherent geological characteristics. This work highlights the variability in the long profile shape of the Ganga River and its major tributaries, its impact on stream power distribution pattern, and role of the geological controls on it. Long profile shapes are represented by the sum of two exponential functions through the curve fitting method. We have shown that coefficients of river long profile equations are governed by the geological characteristics of subbasins. These equations further define the spatial distribution pattern of stream power and help to understand stream power variability in different geological terrains. Spatial distribution of stream power in different geological terrains successfully explains spatial variability in geomorphic processes within the Himalayan hinterland area. In general, the stream power peaks of larger rivers lie in the Higher Himalaya, and rivers in the eastern hinterland area are characterised by the highest magnitude of stream power.

On the patterns and processes of wood in northern California streams

NASA Astrophysics Data System (ADS)

Benda, Lee; Bigelow, Paul

2014-03-01

Forest management and stream habitat can be improved by clarifying the primary riparian and geomorphic controls on streams. To this end, we evaluated the recruitment, storage, transport, and the function of wood in 95 km of streams (most drainage areas < 30 km2) in northern California, crossing four coastal to inland regions with different histories of forest management (managed, less-managed, unmanaged). The dominant source of variability in stream wood storage and recruitment is driven by local variation in rates of bank erosion, forest mortality, and mass wasting. These processes are controlled by changes in watershed structure, including the location of canyons, floodplains and tributary confluences; types of geology and topography; and forest types and management history. Average wood storage volumes in coastal streams are 5 to 20 times greater than inland sites primarily from higher riparian forest biomass and growth rates (productivity), with some influence by longer residence time of wood in streams and more wood from landsliding and logging sources. Wood recruitment by mortality (windthrow, disease, senescence) was substantial across all sites (mean 50%) followed by bank erosion (43%) and more locally by mass wasting (7%). The distances to sources of stream wood are controlled by recruitment process and tree height. Ninety percent of wood recruitment occurs within 10 to 35 m of channels in managed and less-managed forests and upward of 50 m in unmanaged Sequoia and coast redwood forests. Local landsliding extends the source distance. The recruitment of large wood pieces that create jams (mean diameter 0.7 m) is primarily by bank erosion in managed forests and by mortality in unmanaged forests. Formation of pools by wood is more frequent in streams with low stream power, indicating the further relevance of environmental context and watershed structure. Forest management influences stream wood dynamics, where smaller trees in managed forests often generate shorter distances to sources of stream wood, lower stream wood storage, and smaller diameter stream wood. These findings can be used to improve riparian protection and inform spatially explicit riparian management.

Vision for perception and vision for action in the primate brain.

PubMed

Goodale, M A

1998-01-01

Visual systems first evolved not to enable animals to see, but to provide distal sensory control of their movements. Vision as 'sight' is a relative newcomer to the evolutionary landscape, but its emergence has enabled animals to carry out complex cognitive operations on perceptual representations of the world. The two streams of visual processing that have been identified in the primate cerebral cortex are a reflection of these two functions of vision. The dorsal 'action' stream projecting from primary visual cortex to the posterior parietal cortex provides flexible control of more ancient subcortical visuomotor modules for the production of motor acts. The ventral 'perceptual' stream projecting from the primary visual cortex to the temporal lobe provides the rich and detailed representation of the world required for cognitive operations. Both streams process information about the structure of objects and about their spatial locations--and both are subject to the modulatory influences of attention. Each stream, however, uses visual information in different ways. Transformations carried out in the ventral stream permit the formation of perceptual representations that embody the enduring characteristics of objects and their relations; those carried out in the dorsal stream which utilize moment-to-moment information about objects within egocentric frames of reference, mediate the control of skilled actions. Both streams work together in the production of goal-directed behaviour.

Subliminal speech perception and auditory streaming.

PubMed

Dupoux, Emmanuel; de Gardelle, Vincent; Kouider, Sid

2008-11-01

Current theories of consciousness assume a qualitative dissociation between conscious and unconscious processing: while subliminal stimuli only elicit a transient activity, supraliminal stimuli have long-lasting influences. Nevertheless, the existence of this qualitative distinction remains controversial, as past studies confounded awareness and stimulus strength (energy, duration). Here, we used a masked speech priming method in conjunction with a submillisecond interaural delay manipulation to contrast subliminal and supraliminal processing at constant prime, mask and target strength. This delay induced a perceptual streaming effect, with the prime popping out in the supraliminal condition. By manipulating the prime-target interval (ISI), we show a qualitatively distinct profile of priming longevity as a function of prime awareness. While subliminal priming disappeared after half a second, supraliminal priming was independent of ISI. This shows that the distinction between conscious and unconscious processing depends on high-level perceptual streaming factors rather than low-level features (energy, duration).

Functional Mapping of the Human Auditory Cortex: fMRI Investigation of a Patient with Auditory Agnosia from Trauma to the Inferior Colliculus.

PubMed

Poliva, Oren; Bestelmeyer, Patricia E G; Hall, Michelle; Bultitude, Janet H; Koller, Kristin; Rafal, Robert D

2015-09-01

To use functional magnetic resonance imaging to map the auditory cortical fields that are activated, or nonreactive, to sounds in patient M.L., who has auditory agnosia caused by trauma to the inferior colliculi. The patient cannot recognize speech or environmental sounds. Her discrimination is greatly facilitated by context and visibility of the speaker's facial movements, and under forced-choice testing. Her auditory temporal resolution is severely compromised. Her discrimination is more impaired for words differing in voice onset time than place of articulation. Words presented to her right ear are extinguished with dichotic presentation; auditory stimuli in the right hemifield are mislocalized to the left. We used functional magnetic resonance imaging to examine cortical activations to different categories of meaningful sounds embedded in a block design. Sounds activated the caudal sub-area of M.L.'s primary auditory cortex (hA1) bilaterally and her right posterior superior temporal gyrus (auditory dorsal stream), but not the rostral sub-area (hR) of her primary auditory cortex or the anterior superior temporal gyrus in either hemisphere (auditory ventral stream). Auditory agnosia reflects dysfunction of the auditory ventral stream. The ventral and dorsal auditory streams are already segregated as early as the primary auditory cortex, with the ventral stream projecting from hR and the dorsal stream from hA1. M.L.'s leftward localization bias, preserved audiovisual integration, and phoneme perception are explained by preserved processing in her right auditory dorsal stream.

Water Stage Forecasting in Tidal streams during High Water Using EEMD

NASA Astrophysics Data System (ADS)

Chen, Yen-Chang; Kao, Su-Pai; Su, Pei-Yi

2017-04-01

There are so many factors may affect the water stages in tidal streams. Not only the ocean wave but also the stream flow affects the water stage in a tidal stream. During high water, two of the most important factors affecting water stages in tidal streams are flood and tide. However the hydrological processes in tidal streams during high water are nonlinear and nonstationary. Generally the conventional methods used for forecasting water stages in tidal streams are very complicated. It explains the accurately forecasting water stages, especially during high water, in tidal streams is always a difficult task. The study makes used of Ensemble Empirical Model Decomposition (EEMD) to analyze the water stages in tidal streams. One of the advantages of the EEMD is it can be used to analyze the nonlinear and nonstationary data. The EEMD divides the water stage into several intrinsic mode functions (IMFs) and a residual; meanwhile, the physical meaning still remains during the process. By comparing the IMF frequency with tidal frequency, it is possible to identify if the IMF is affected by tides. Then the IMFs is separated into two groups, affected by tide or not by tide. The IMFs in each group are assembled to become a factor. Therefore the water stages in tidal streams are only affected by two factors, tidal factor and flood factor. Finally the regression analysis is used to establish the relationship between the factors of the gaging stations in the tidal stream. The available data during 15 typhoon periods of the Tanshui River whose downstream reach is in estuary area is used to illustrate the accuracy and reliability of the proposed method. The results show that the simple but reliable method is capable of forecasting water stages in tidal streams.

Enhanced Fine-Form Perception Does Not Contribute to Gestalt Face Perception in Autism Spectrum Disorder

PubMed Central

Maekawa, Toshihiko; Miyanaga, Yuka; Takahashi, Kenji; Takamiya, Naomi; Ogata, Katsuya; Tobimatsu, Shozo

2017-01-01

Individuals with autism spectrum disorder (ASD) show superior performance in processing fine detail, but often exhibit impaired gestalt face perception. The ventral visual stream from the primary visual cortex (V1) to the fusiform gyrus (V4) plays an important role in form (including faces) and color perception. The aim of this study was to investigate how the ventral stream is functionally altered in ASD. Visual evoked potentials were recorded in high-functioning ASD adults (n = 14) and typically developing (TD) adults (n = 14). We used three types of visual stimuli as follows: isoluminant chromatic (red/green, RG) gratings, high-contrast achromatic (black/white, BW) gratings with high spatial frequency (HSF, 5.3 cycles/degree), and face (neutral, happy, and angry faces) stimuli. Compared with TD controls, ASD adults exhibited longer N1 latency for RG, shorter N1 latency for BW, and shorter P1 latency, but prolonged N170 latency, for face stimuli. Moreover, a greater difference in latency between P1 and N170, or between N1 for BW and N170 (i.e., the prolongation of cortico-cortical conduction time between V1 and V4) was observed in ASD adults. These findings indicate that ASD adults have enhanced fine-form (local HSF) processing, but impaired color processing at V1. In addition, they exhibit impaired gestalt face processing due to deficits in integration of multiple local HSF facial information at V4. Thus, altered ventral stream function may contribute to abnormal social processing in ASD. PMID:28146575

Weighing the evidence for a dorsal processing bias under continuous flash suppression.

PubMed

Ludwig, Karin; Hesselmann, Guido

2015-09-01

With the introduction of continuous flash suppression (CFS) as a method to render stimuli invisible and study unconscious visual processing, a novel hypothesis has gained popularity. It states that processes typically ascribed to the dorsal visual stream can escape CFS and remain functional, while ventral stream processes are suppressed when stimuli are invisible under CFS. This notion of a CFS-specific "dorsal processing bias" has been argued to be in line with core characteristics of the influential dual-stream hypothesis of visual processing which proposes a dissociation between dorsally mediated vision-for-action and ventrally mediated vision-for-perception. Here, we provide an overview of neuroimaging and behavioral studies that either examine this dorsal processing bias or base their conclusions on it. We show that both evidence for preserved ventral processing as well as lack of dorsal processing can be found in studies using CFS. To reconcile the diverging results, differences in the paradigms and their effects are worthy of future research. We conclude that given the current level of information a dorsal processing bias under CFS cannot be universally assumed. Copyright © 2014 Elsevier Inc. All rights reserved.

Spatial Mechanisms within the Dorsal Visual Pathway Contribute to the Configural Processing of Faces.

PubMed

Zachariou, Valentinos; Nikas, Christine V; Safiullah, Zaid N; Gotts, Stephen J; Ungerleider, Leslie G

2017-08-01

Human face recognition is often attributed to configural processing; namely, processing the spatial relationships among the features of a face. If configural processing depends on fine-grained spatial information, do visuospatial mechanisms within the dorsal visual pathway contribute to this process? We explored this question in human adults using functional magnetic resonance imaging and transcranial magnetic stimulation (TMS) in a same-different face detection task. Within localized, spatial-processing regions of the posterior parietal cortex, configural face differences led to significantly stronger activation compared to featural face differences, and the magnitude of this activation correlated with behavioral performance. In addition, detection of configural relative to featural face differences led to significantly stronger functional connectivity between the right FFA and the spatial processing regions of the dorsal stream, whereas detection of featural relative to configural face differences led to stronger functional connectivity between the right FFA and left FFA. Critically, TMS centered on these parietal regions impaired performance on configural but not featural face difference detections. We conclude that spatial mechanisms within the dorsal visual pathway contribute to the configural processing of facial features and, more broadly, that the dorsal stream may contribute to the veridical perception of faces. Published by Oxford University Press 2016.

Maps and streams in the auditory cortex: nonhuman primates illuminate human speech processing

PubMed Central

Rauschecker, Josef P; Scott, Sophie K

2010-01-01

Speech and language are considered uniquely human abilities: animals have communication systems, but they do not match human linguistic skills in terms of recursive structure and combinatorial power. Yet, in evolution, spoken language must have emerged from neural mechanisms at least partially available in animals. In this paper, we will demonstrate how our understanding of speech perception, one important facet of language, has profited from findings and theory in nonhuman primate studies. Chief among these are physiological and anatomical studies showing that primate auditory cortex, across species, shows patterns of hierarchical structure, topographic mapping and streams of functional processing. We will identify roles for different cortical areas in the perceptual processing of speech and review functional imaging work in humans that bears on our understanding of how the brain decodes and monitors speech. A new model connects structures in the temporal, frontal and parietal lobes linking speech perception and production. PMID:19471271

Comparative Study on Interaction of Form and Motion Processing Streams by Applying Two Different Classifiers in Mechanism for Recognition of Biological Movement

PubMed Central

2014-01-01

Research on psychophysics, neurophysiology, and functional imaging shows particular representation of biological movements which contains two pathways. The visual perception of biological movements formed through the visual system called dorsal and ventral processing streams. Ventral processing stream is associated with the form information extraction; on the other hand, dorsal processing stream provides motion information. Active basic model (ABM) as hierarchical representation of the human object had revealed novelty in form pathway due to applying Gabor based supervised object recognition method. It creates more biological plausibility along with similarity with original model. Fuzzy inference system is used for motion pattern information in motion pathway creating more robustness in recognition process. Besides, interaction of these paths is intriguing and many studies in various fields considered it. Here, the interaction of the pathways to get more appropriated results has been investigated. Extreme learning machine (ELM) has been implied for classification unit of this model, due to having the main properties of artificial neural networks, but crosses from the difficulty of training time substantially diminished in it. Here, there will be a comparison between two different configurations, interactions using synergetic neural network and ELM, in terms of accuracy and compatibility. PMID:25276860

Considerations of Scale and Processes in Stream Restoration and Ecological Response

NASA Astrophysics Data System (ADS)

Simon, A.; Shields, D.; Kuhnle, R.; Knight, S.

2005-12-01

Stream restoration as a means of controlling accelerated channel erosion and improving biological function in streams has become pervasive in the United States over the past twenty years. A broad range of practices often involving direct modifications to stream channels and adjacent floodplains, including alterations to morphology and pattern have been used for stream restoration. Because alluvial-channel processes and biological functioning operate as linked, open systems, any restoration project must be placed in the context of existing watershed and channel processes with a quantitative understanding of the rates of transfer of flow energy and materials. This is particularly true of reach-scale projects where local stabilization and habitat improvements may be completely overwhelmed by watershed or channel-system scale instabilities. In this regard, it is unlikely that a reach-scale project will be successful in an unstable alluvial system. This is analogous to constructing bank-stabilization measures in an actively incising channel. A conceptual model of channel response and evolution that marks systematic shifts in channel processes over time and space has been linked to fish-community structure in Mississippi streams. This link reflects changing habitat conditions and sediment-transport regimes over the course of fluvial adjustment. Suspended-sediment concentrations that can increase by orders of magnitude for a given discharge during the incision and mass-wasting phases abrade fish gills and reduce the ability of fish to hunt for food due to reduced water clarity. Similarly, durations of high suspended-sediment concentrations are shown to be inversely related to numbers of benthic macro invertebrates. Streambeds experiencing active incision (Stage III) may be too mobile for benthic macro invertebrate communities to thrive. Channels dominated by mass-wasting processes (Stages IV and V) lose riparian vegetative cover and shading which may result in higher stream temperatures. Aggradation processes typical of Stage V result in loss of interstitial spaces for spawning, de-oxygenation of substrate and may suffocate organisms. Perhaps most importantly, channel widening produces shallower depths at base flow and renders streams less retentive of large wood. Ecological characteristics recover in advanced stages of channel evolution as baseflow channels are narrowed and berms re-vegetate (Stage VI), but full recovery to pre-incision (Stage I) conditions has not been observed for both ecologic and sediment-transport systems. The processes reflected by stages of evolution can operate over entire fluvial networks and over time scales in the order of 100 years. Issues regarding effectiveness or benefit of stream restoration practices, therefore, must address scale. Furthermore, site and approach selection for reach-scale restoration projects should be guided by knowledge of watershed-scale processes. As an example, a grade control structure installed on Hotophia Creek, Mississippi successfully eliminated upstream-progressing incision and resulted in locally improved aquatic populations in the stilling basin. However, the trapping of hydraulically-controlled sediment on the upstream side of the structure resulted in streambed incision, de-stabilization of streambanks and degraded aquatic habitat in downstream reaches not protected by other grade-control structures.

An evaluation of light intensity functions for determination of shaded reference stream metabolism.

PubMed

Zell, Chris; Hubbart, Jason A

2012-04-30

The performance of three single-station whole stream metabolism models were evaluated within three shaded, seasonally hypoxic, Missouri reference streams using high resolution (15-minute) dissolved oxygen (DO), temperature, and light intensity data collected during the summers (July-September) of 2006-2008. The model incorporating light intensity data consistently achieved a lower root mean square error (median RMSE = 0.20 mg L(-1)) relative to models assuming sinusoidal light intensity functions (median RMSE = 0.28 mg L(-1)) and constant diel temperature (median RMSE = 0.53 mg L(-1)). Incorporation of site-specific light intensity into metabolism models better predicted morning DO concentrations and exposure to hypoxic conditions in shaded study streams. Model choice significantly affected (p < 0.05) rate estimates for daily average photosynthesis. Low reaeration (pooled site mean 1.1 day(-1) at 20 °C) coupled with summer temperatures (pooled site mean = 25.8 °C) and low to moderate community respiration (site median 1.0-3.0 g O(2) m(-2) day(-1)) yielded diel dissolved oxygen concentrations near or below critical aquatic life thresholds in studied reference streams. Quantifying these process combinations in best-available or least-disturbed (i.e., reference) systems advances our understanding of regional dissolved oxygen expectations and informs environmental management policy. Additional research is warranted to better link landscape processes with distributed sources that contribute to community respiration. Copyright © 2011 Elsevier Ltd. All rights reserved.

Long-term enrichment of the stable isotopic composition of stream water due to the release of groundwater recharge from extreme precipitation events

NASA Astrophysics Data System (ADS)

Boutt, D. F.

2017-12-01

The isotopic composition of surface and groundwater is impacted by a multitude of hydrologic processes. The long-term response of these systems to hydrologic change is critical for appropriately interpreting isotopic information for streamflow generation, stream-aquifer-coupling, sources of water to wells, and understanding recharge processes. To evaluate the response time of stream-aquifer systems to extreme precipitation events we use a long-term isotope dataset from Western Massachusetts with drainage areas ranging from 0.1 to > 800 km2. The year of 2011 was the wettest calendar year on record and the months of August and September of 2011 were the wettest consecutive two-month period in the 123 year record. Stable isotopic composition of surface waters of catchments ranging from 1 - 1000 km2 show an enrichment due to summertime and Tropical Storm precipitation. Enrichment in potential recharge water is shown to have a significant long-term impact (> 3 hydrologic years) on the isotopic composition of both surface and groundwater. This highlights the importance of groundwater sources of baseflow to streams and the transient storage and release mechanisms of shallow groundwater storage. The length of isotopic recession of stream water are also a strong function of watershed area. It is concluded that the stream water isotopes are consistent with a large pulse of water being stored and released from enriched groundwater emplaced during this period of above-average precipitation. Ultimately the results point to the importance of considering hydrological processes of streamflow generation and their role in hydrologic processes beyond traditional catchment response analysis.

Generation rates and chemical compositions of waste streams in a typical crewed space habitat

NASA Technical Reports Server (NTRS)

Wydeven, Theodore; Golub, Morton A.

1990-01-01

A judicious compilation of generation rates and chemical compositions of potential waste feed streams in a typical crewed space habitat was made in connection with the waste-management aspect of NASA's Physical/Chemical Closed-Loop Life Support Program. Waste composition definitions are needed for the design of waste-processing technologies involved in closing major life support functions in future long-duration human space missions. Tables of data for the constituents and chemical formulas of the following waste streams are presented and discussed: human urine, feces, hygiene (laundry and shower) water, cleansing agents, trash, humidity condensate, dried sweat, and trace contaminants. Tables of data on dust generation and pH values of the different waste streams are also presented and discussed.

Effects of Resource Chemistry on the Composition and Function of Stream Hyporheic Biofilms

PubMed Central

Hall, E. K.; Besemer, K.; Kohl, L.; Preiler, C.; Riedel, K.; Schneider, T.; Wanek, W.; Battin, T. J.

2012-01-01

Fluvial ecosystems process large quantities of dissolved organic matter as it moves from the headwater streams to the sea. In particular, hyporheic sediments are centers of high biogeochemical reactivity due to their elevated residence time and high microbial biomass and activity. However, the interaction between organic matter and microbial dynamics in the hyporheic zone remains poorly understood. We evaluated how variance in resource chemistry affected the microbial community and its associated activity in experimentally grown hyporheic biofilms. To do this we fed beech leaf leachates that differed in chemical composition to a series of bioreactors filled with sediment from a sub-alpine stream. Differences in resource chemistry resulted in differences in diversity and phylogenetic origin of microbial proteins, enzyme activity, and microbial biomass stoichiometry. Specifically, increased lignin, phenolics, and manganese in a single leachate resulted in increased phenoloxidase and peroxidase activity, elevated microbial biomass carbon:nitrogen ratio, and a greater proportion of proteins of Betaproteobacteria origin. We used this model system to attempt to link microbial form (community composition and metaproteome) with function (enzyme activity) in order to better understand the mechanisms that link resource heterogeneity to ecosystem function in stream ecosystems. PMID:22347877

Effects of resource chemistry on the composition and function of stream hyporheic biofilms.

USGS Publications Warehouse

Hall, E.K.; Besemer, K.; Kohl, L.; Preiler, C.; Reidel, K.; Schneider, T.; Wanek, W.; Battin, T.J.

2012-01-01

Fluvial ecosystems process large quantities of dissolved organic matter as it moves from the headwater streams to the sea. In particular, hyporheic sediments are centers of high biogeochemical reactivity due to their elevated residence time and high microbial biomass and activity. However, the interaction between organic matter and microbial dynamics in the hyporheic zone remains poorly understood. We evaluated how variance in resource chemistry affected the microbial community and its associated activity in experimentally grown hyporheic biofilms. To do this we fed beech leaf leachates that differed in chemical composition to a series of bioreactors filled with sediment from a sub-alpine stream. Differences in resource chemistry resulted in differences in diversity and phylogenetic origin of microbial proteins, enzyme activity, and microbial biomass stoichiometry. Specifically, increased lignin, phenolics, and manganese in a single leachate resulted in increased phenoloxidase and peroxidase activity, elevated microbial biomass carbon:nitrogen ratio, and a greater proportion of proteins of Betaproteobacteria origin. We used this model system to attempt to link microbial form (community composition and metaproteome) with function (enzyme activity) in order to better understand the mechanisms that link resource heterogeneity to ecosystem function in stream ecosystems.

A viscous flow analysis for the tip vortex generation process

NASA Technical Reports Server (NTRS)

Shamroth, S. J.; Briley, W. R.

1979-01-01

A three dimensional, forward-marching, viscous flow analysis is applied to the tip vortex generation problem. The equations include a streamwise momentum equation, a streamwise vorticity equation, a continuity equation, and a secondary flow stream function equation. The numerical method used combines a consistently split linearized scheme for parabolic equations with a scalar iterative ADI scheme for elliptic equations. The analysis is used to identify the source of the tip vortex generation process, as well as to obtain detailed flow results for a rectangular planform wing immersed in a high Reynolds number free stream at 6 degree incidence.

A single dual-stream framework for syntactic computations in music and language.

PubMed

Musso, Mariacristina; Weiller, Cornelius; Horn, Andreas; Glauche, Volkmer; Umarova, Roza; Hennig, Jürgen; Schneider, Albrecht; Rijntjes, Michel

2015-08-15

This study is the first to compare in the same subjects the specific spatial distribution and the functional and anatomical connectivity of the neuronal resources that activate and integrate syntactic representations during music and language processing. Combining functional magnetic resonance imaging with functional connectivity and diffusion tensor imaging-based probabilistic tractography, we examined the brain network involved in the recognition and integration of words and chords that were not hierarchically related to the preceding syntax; that is, those deviating from the universal principles of grammar and tonal relatedness. This kind of syntactic processing in both domains was found to rely on a shared network in the left hemisphere centered on the inferior part of the inferior frontal gyrus (IFG), including pars opercularis and pars triangularis, and on dorsal and ventral long association tracts connecting this brain area with temporo-parietal regions. Language processing utilized some adjacent left hemispheric IFG and middle temporal regions more than music processing, and music processing also involved right hemisphere regions not activated in language processing. Our data indicate that a dual-stream system with dorsal and ventral long association tracts centered on a functionally and structurally highly differentiated left IFG is pivotal for domain-general syntactic competence over a broad range of elements including words and chords. Copyright © 2015 Elsevier Inc. All rights reserved.

Predicting and generalizing the refuge function of intermittent and ephemeral streams

EPA Science Inventory

Intermittent and ephemeral streams can provide important functions within stream networks. For fish, intermittent and ephemeral streams can contribute energy and materials to downstream perennial waters, serve as seasonal habitats, and/or provide refuge functions. Understanding t...

It Takes Two–Skilled Recognition of Objects Engages Lateral Areas in Both Hemispheres

PubMed Central

Bilalić, Merim; Kiesel, Andrea; Pohl, Carsten; Erb, Michael; Grodd, Wolfgang

2011-01-01

Our object recognition abilities, a direct product of our experience with objects, are fine-tuned to perfection. Left temporal and lateral areas along the dorsal, action related stream, as well as left infero-temporal areas along the ventral, object related stream are engaged in object recognition. Here we show that expertise modulates the activity of dorsal areas in the recognition of man-made objects with clearly specified functions. Expert chess players were faster than chess novices in identifying chess objects and their functional relations. Experts' advantage was domain-specific as there were no differences between groups in a control task featuring geometrical shapes. The pattern of eye movements supported the notion that experts' extensive knowledge about domain objects and their functions enabled superior recognition even when experts were not directly fixating the objects of interest. Functional magnetic resonance imaging (fMRI) related exclusively the areas along the dorsal stream to chess specific object recognition. Besides the commonly involved left temporal and parietal lateral brain areas, we found that only in experts homologous areas on the right hemisphere were also engaged in chess specific object recognition. Based on these results, we discuss whether skilled object recognition does not only involve a more efficient version of the processes found in non-skilled recognition, but also qualitatively different cognitive processes which engage additional brain areas. PMID:21283683

Two different streams form the dorsal visual system: anatomy and functions.

PubMed

Rizzolatti, Giacomo; Matelli, Massimo

2003-11-01

There are two radically different views on the functional role of the dorsal visual stream. One considers it as a system involved in space perception. The other is of a system that codes visual information for action organization. On the basis of new anatomical data and a reconsideration of previous functional and clinical data, we propose that the dorsal stream and its recipient parietal areas form two distinct functional systems: the dorso-dorsal stream (d-d stream) and the ventro-dorsal stream (v-d stream). The d-d stream is formed by area V6 (main d-d extrastriate visual node) and areas V6A and MIP of the superior parietal lobule. Its major functional role is the control of actions "on line". Its damage leads to optic ataxia. The v-d stream is formed by area MT (main v-d extrastriate visual node) and by the visual areas of the inferior parietal lobule. As the d-d stream, v-d stream is responsible for action organization. It, however, also plays a crucial role in space perception and action understanding. The putative mechanisms linking action and perception in the v-d stream is discussed.

Organization and evolution of parieto-frontal processing streams in macaque monkeys and humans.

PubMed

Caminiti, Roberto; Innocenti, Giorgio M; Battaglia-Mayer, Alexandra

2015-09-01

The functional organization of the parieto-frontal system is crucial for understanding cognitive-motor behavior and provides the basis for interpreting the consequences of parietal lesions in humans from a neurobiological perspective. The parieto-frontal connectivity defines some main information streams that, rather than being devoted to restricted functions, underlie a rich behavioral repertoire. Surprisingly, from macaque to humans, evolution has added only a few, new functional streams, increasing however their complexity and encoding power. In fact, the characterization of the conduction times of parietal and frontal areas to different target structures has recently opened a new window on cortical dynamics, suggesting that evolution has amplified the probability of dynamic interactions between the nodes of the network, thanks to communication patterns based on temporally-dispersed conduction delays. This might allow the representation of sensory-motor signals within multiple neural assemblies and reference frames, as to optimize sensory-motor remapping within an action space characterized by different and more complex demands across evolution. Copyright © 2015 Elsevier Ltd. All rights reserved.

High data volume and transfer rate techniques used at NASA's image processing facility

NASA Technical Reports Server (NTRS)

Heffner, P.; Connell, E.; Mccaleb, F.

1978-01-01

Data storage and transfer operations at a new image processing facility are described. The equipment includes high density digital magnetic tape drives and specially designed controllers to provide an interface between the tape drives and computerized image processing systems. The controller performs the functions necessary to convert the continuous serial data stream from the tape drive to a word-parallel blocked data stream which then goes to the computer-based system. With regard to the tape packing density, 1.8 times 10 to the tenth data bits are stored on a reel of one-inch tape. System components and their operation are surveyed, and studies on advanced storage techniques are summarized.

Real-Time Cognitive Computing Architecture for Data Fusion in a Dynamic Environment

NASA Technical Reports Server (NTRS)

Duong, Tuan A.; Duong, Vu A.

2012-01-01

A novel cognitive computing architecture is conceptualized for processing multiple channels of multi-modal sensory data streams simultaneously, and fusing the information in real time to generate intelligent reaction sequences. This unique architecture is capable of assimilating parallel data streams that could be analog, digital, synchronous/asynchronous, and could be programmed to act as a knowledge synthesizer and/or an "intelligent perception" processor. In this architecture, the bio-inspired models of visual pathway and olfactory receptor processing are combined as processing components, to achieve the composite function of "searching for a source of food while avoiding the predator." The architecture is particularly suited for scene analysis from visual data and odorant.

Discretized Streams: A Fault-Tolerant Model for Scalable Stream Processing

DTIC Science & Technology

2012-12-14

Discretized Streams: A Fault-Tolerant Model for Scalable Stream Processing Matei Zaharia Tathagata Das Haoyuan Li Timothy Hunter Scott Shenker Ion...SUBTITLE Discretized Streams: A Fault-Tolerant Model for Scalable Stream Processing 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER...time. However, current programming models for distributed stream processing are relatively low-level often leaving the user to worry about consistency of

Taxonomic and Functional Differences between Microbial Communities in Qinghai Lake and Its Input Streams

PubMed Central

Ren, Ze; Wang, Fang; Qu, Xiaodong; Elser, James J.; Liu, Yang; Chu, Limin

2017-01-01

Understanding microbial communities in terms of taxon and function is essential to decipher the biogeochemical cycling in aquatic ecosystems. Lakes and their input streams are highly linked. However, the differences between microbial assemblages in streams and lakes are still unclear. In this study, we conducted an intensive field sampling of microbial communities from lake water and stream biofilms in the Qinghai Lake watershed, the largest lake in China. We determined bacterial communities using high-throughput 16S rRNA gene sequencing and predicted functional profiles using PICRUSt to determine the taxonomic and functional differences between microbial communities in stream biofilms and lake water. The results showed that stream biofilms and lake water harbored distinct microbial communities. The microbial communities were different taxonomically and functionally between stream and lake. Moreover, streams biofilms had a microbial network with higher connectivity and modularity than lake water. Functional beta diversity was strongly correlated with taxonomic beta diversity in both the stream and lake microbial communities. Lake microbial assemblages displayed greater predicted metabolic potentials of many metabolism pathways while the microbial assemblages in stream biofilms were more abundant in xenobiotic biodegradation and metabolism and lipid metabolism. Furthermore, lake microbial assemblages had stronger predicted metabolic potentials in amino acid metabolism, carbon fixation, and photosynthesis while stream microbial assemblages were higher in carbohydrate metabolism, oxidative phosphorylation, and nitrogen metabolism. This study adds to our knowledge of stream-lake linkages from the functional and taxonomic composition of microbial assemblages. PMID:29213266

40 CFR 63.981 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... an enclosed combustion device that transfers heat liberated by burning fuel directly to process streams or to heat transfer liquids other than water. A process heater may, as a secondary function, heat... means gases that are combusted to derive useful work or heat. Fuel gas system means the offsite and...

Kinesthetic working memory and action control within the dorsal stream.

PubMed

Fiehler, Katja; Burke, Michael; Engel, Annerose; Bien, Siegfried; Rösler, Frank

2008-02-01

There is wide agreement that the "dorsal (action) stream" processes visual information for movement control. However, movements depend not only on vision but also on tactile and kinesthetic information (=haptics). Using functional magnetic resonance imaging, the present study investigates to what extent networks within the dorsal stream are also utilized for kinesthetic action control and whether they are also involved in kinesthetic working memory. Fourteen blindfolded participants performed a delayed-recognition task in which right-handed movements had to be encoded, maintained, and later recognized without any visual feedback. Encoding of hand movements activated somatosensory areas, superior parietal lobe (dorsodorsal stream), anterior intraparietal sulcus (aIPS) and adjoining areas (ventrodorsal stream), premotor cortex, and occipitotemporal cortex (ventral stream). Short-term maintenance of kinesthetic information elicited load-dependent activity in the aIPS and adjacent anterior portion of the superior parietal lobe (ventrodorsal stream) of the left hemisphere. We propose that the action representation system of the dorsodorsal and ventrodorsal stream is utilized not only for visual but also for kinesthetic action control. Moreover, the present findings demonstrate that networks within the ventrodorsal stream, in particular the left aIPS and closely adjacent areas, are also engaged in working memory maintenance of kinesthetic information.

Neotropical Amphibian Declines Affect Stream Ecosystem Properties

NASA Astrophysics Data System (ADS)

Connelly, S.; Pringle, C. M.; Bixby, R. J.; Whiles, M. R.; Lips, K. R.; Brenes, R.; Colon-Gaud, J. C.; Kilham, S.; Hunte-Brown, M.

2005-05-01

Global declines of amphibians are well documented, yet effects of these dramatic losses on ecosystem structure and function are poorly understood. As part of a larger collaborative project, we compared two upland Panamanian streams. Both streams are biologically and geologically similar; however, one stream (Fortuna) has recently experienced almost complete extirpation of stream-dwelling frogs, while the other (Cope) still has intact populations. We experimentally excluded tadpoles from localized areas in each stream. We then compared chlorophyll a, algal community composition, ash-free dry mass (AFDM), inorganic matter, and insect assemblages in control and exclusion areas. Additionally, we sampled the natural substrate of both streams monthly for chlorophyll a, algal community composition, AFDM, and inorganic matter. At Cope, chlorophyll a, AFDM, and inorganic matter were greater in areas where tadpoles were excluded than in their presence. Numbers of dominant algal species (e.g., Nupela praecipua and Eunotia siolii) were greater in the exclusion versus control treatments. Monthly sampling of natural substrate indicated higher chlorophyll a and AFDM at Cope compared to Fortuna. Our data suggest that stream-dwelling anuran larvae have significant impacts on algal communities. These results also have implications for predicting the relevance of short-term experimental manipulations to long-term, whole-stream processes.

Hydrologic landscape regions for predicting and generalizing the refuge function of intermittent and ephemeral streams

EPA Science Inventory

Intermittent and ephemeral (IE) streams can provide important functions within stream networks. Understanding the relative benefit provided to downstream waters is needed to better inform watershed management. Although the potential functions of IE streams are relatively well kn...

Dynamic modeling of nitrogen losses in river networks unravels the coupled effects of hydrological and biogeochemical processes

USGS Publications Warehouse

Alexander, Richard B.; Böhlke, John Karl; Boyer, Elizabeth W.; David, Mark B.; Harvey, Judson W.; Mulholland, Patrick J.; Seitzinger, Sybil P.; Tobias, Craig R.; Tonitto, Christina; Wollheim, Wilfred M.

2009-01-01

The importance of lotic systems as sinks for nitrogen inputs is well recognized. A fraction of nitrogen in streamflow is removed to the atmosphere via denitrification with the remainder exported in streamflow as nitrogen loads. At the watershed scale, there is a keen interest in understanding the factors that control the fate of nitrogen throughout the stream channel network, with particular attention to the processes that deliver large nitrogen loads to sensitive coastal ecosystems. We use a dynamic stream transport model to assess biogeochemical (nitrate loadings, concentration, temperature) and hydrological (discharge, depth, velocity) effects on reach-scale denitrification and nitrate removal in the river networks of two watersheds having widely differing levels of nitrate enrichment but nearly identical discharges. Stream denitrification is estimated by regression as a nonlinear function of nitrate concentration, streamflow, and temperature, using more than 300 published measurements from a variety of US streams. These relations are used in the stream transport model to characterize nitrate dynamics related to denitrification at a monthly time scale in the stream reaches of the two watersheds. Results indicate that the nitrate removal efficiency of streams, as measured by the percentage of the stream nitrate flux removed via denitrification per unit length of channel, is appreciably reduced during months with high discharge and nitrate flux and increases during months of low-discharge and flux. Biogeochemical factors, including land use, nitrate inputs, and stream concentrations, are a major control on reach-scale denitrification, evidenced by the disproportionately lower nitrate removal efficiency in streams of the highly nitrate-enriched watershed as compared with that in similarly sized streams in the less nitrate-enriched watershed. Sensitivity analyses reveal that these important biogeochemical factors and physical hydrological factors contribute nearly equally to seasonal and stream-size related variations in the percentage of the stream nitrate flux removed in each watershed.

Network analysis of corticocortical connections reveals ventral and dorsal processing streams in mouse visual cortex

PubMed Central

Wang, Quanxin; Sporns, Olaf; Burkhalter, Andreas

2012-01-01

Much of the information used for visual perception and visually guided actions is processed in complex networks of connections within the cortex. To understand how this works in the normal brain and to determine the impact of disease, mice are promising models. In primate visual cortex, information is processed in a dorsal stream specialized for visuospatial processing and guided action and a ventral stream for object recognition. Here, we traced the outputs of 10 visual areas and used quantitative graph analytic tools of modern network science to determine, from the projection strengths in 39 cortical targets, the community structure of the network. We found a high density of the cortical graph that exceeded that previously shown in monkey. Each source area showed a unique distribution of projection weights across its targets (i.e. connectivity profile) that was well-fit by a lognormal function. Importantly, the community structure was strongly dependent on the location of the source area: outputs from medial/anterior extrastriate areas were more strongly linked to parietal, motor and limbic cortex, whereas lateral extrastriate areas were preferentially connected to temporal and parahippocampal cortex. These two subnetworks resemble dorsal and ventral cortical streams in primates, demonstrating that the basic layout of cortical networks is conserved across species. PMID:22457489

Large-scale structure perturbation theory without losing stream crossing

NASA Astrophysics Data System (ADS)

McDonald, Patrick; Vlah, Zvonimir

2018-01-01

We suggest an approach to perturbative calculations of large-scale clustering in the Universe that includes from the start the stream crossing (multiple velocities for mass elements at a single position) that is lost in traditional calculations. Starting from a functional integral over displacement, the perturbative series expansion is in deviations from (truncated) Zel'dovich evolution, with terms that can be computed exactly even for stream-crossed displacements. We evaluate the one-loop formulas for displacement and density power spectra numerically in 1D, finding dramatic improvement in agreement with N-body simulations compared to the Zel'dovich power spectrum (which is exact in 1D up to stream crossing). Beyond 1D, our approach could represent an improvement over previous expansions even aside from the inclusion of stream crossing, but we have not investigated this numerically. In the process we show how to achieve effective-theory-like regulation of small-scale fluctuations without free parameters.

Auditory scene analysis in school-aged children with developmental language disorders

PubMed Central

Sussman, E.; Steinschneider, M.; Lee, W.; Lawson, K.

2014-01-01

Natural sound environments are dynamic, with overlapping acoustic input originating from simultaneously active sources. A key function of the auditory system is to integrate sensory inputs that belong together and segregate those that come from different sources. We hypothesized that this skill is impaired in individuals with phonological processing difficulties. There is considerable disagreement about whether phonological impairments observed in children with developmental language disorders can be attributed to specific linguistic deficits or to more general acoustic processing deficits. However, most tests of general auditory abilities have been conducted with a single set of sounds. We assessed the ability of school-aged children (7–15 years) to parse complex auditory non-speech input, and determined whether the presence of phonological processing impairments was associated with stream perception performance. A key finding was that children with language impairments did not show the same developmental trajectory for stream perception as typically developing children. In addition, children with language impairments required larger frequency separations between sounds to hear distinct streams compared to age-matched peers. Furthermore, phonological processing ability was a significant predictor of stream perception measures, but only in the older age groups. No such association was found in the youngest children. These results indicate that children with language impairments have difficulty parsing speech streams, or identifying individual sound events when there are competing sound sources. We conclude that language group differences may in part reflect fundamental maturational disparities in the analysis of complex auditory scenes. PMID:24548430

Restoration of Gooseberry Creek

Treesearch

Jonathan W. Long

2000-01-01

Grazing exclusion and channel modifications were used to restore wet meadows along a stream on the Fort Apache Indian Reservation. The efforts are reestablishing functional processes to promote long-term restoration of wetland health and species conservation.

A parallel Jacobson-Oksman optimization algorithm. [parallel processing (computers)

NASA Technical Reports Server (NTRS)

Straeter, T. A.; Markos, A. T.

1975-01-01

A gradient-dependent optimization technique which exploits the vector-streaming or parallel-computing capabilities of some modern computers is presented. The algorithm, derived by assuming that the function to be minimized is homogeneous, is a modification of the Jacobson-Oksman serial minimization method. In addition to describing the algorithm, conditions insuring the convergence of the iterates of the algorithm and the results of numerical experiments on a group of sample test functions are presented. The results of these experiments indicate that this algorithm will solve optimization problems in less computing time than conventional serial methods on machines having vector-streaming or parallel-computing capabilities.

Neural Substrates for Processing Task-Irrelevant Sad Images in Adolescents

ERIC Educational Resources Information Center

Wang, Lihong; Huettel, Scott; De Bellis, Michael D.

2008-01-01

Neural systems related to cognitive and emotional processing were examined in adolescents using event-related functional magnetic resonance imaging (fMRI). Ten healthy adolescents performed an emotional oddball task. Subjects detected infrequent circles (targets) within a continual stream of phase-scrambled images (standards). Sad and neutral…

Method for enhanced atomization of liquids

DOEpatents

Thompson, Richard E.; White, Jerome R.

1993-01-01

In a process for atomizing a slurry or liquid process stream in which a slurry or liquid is passed through a nozzle to provide a primary atomized process stream, an improvement which comprises subjecting the liquid or slurry process stream to microwave energy as the liquid or slurry process stream exits the nozzle, wherein sufficient microwave heating is provided to flash vaporize the primary atomized process stream.

Environmental research program for slagging fixed-bed coal gasification. Status report, November 1981

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

Wilzbach, K. E.; Stetter, J. R.; Reilly, Jr., C. A.

1982-02-01

A collaborative environmental research program to provide information needed to assess the health and environmental effects associated with large-scale coal gasification technology is being conducted by Argonne National Laboratory (ANL) and the Grand Forks Energy Technology Center (GFETC). The objectives are to: investigate the toxicology and chemical composition of coal gasification by-products as a function of process variables and coal feed; compare the characteristics of isokinetic side-stream samples with those of process stream samples; identify the types of compounds responsible for toxicity; evaluate the chemical and toxicological effectiveness of various wastewater treatment operations; refine methodology for the collection and measurementmore » of organic vapors and particulates in workplace air; and obtain preliminary data on workplace air quality. So far the toxicities of a set of process stream samples (tar, oil, and gas liquor) and side-stream condensates from the GFETC gasifier have been measured in a battery of cellular screening tests for mutagenicity and cytotoxicity. Preliminary data on the effects of acute and chronic exposures of laboratory animals to process tar have been obtained. The process tar has been chemically fractionated and the distribution of mutagenicity and compound types among the fractions has been determined. Organic vapors and particulates collected at various times and locations in the gasifier building have been characterized.« less

Person perception involves functional integration between the extrastriate body area and temporal pole.

PubMed

Greven, Inez M; Ramsey, Richard

2017-02-01

The majority of human neuroscience research has focussed on understanding functional organisation within segregated patches of cortex. The ventral visual stream has been associated with the detection of physical features such as faces and body parts, whereas the theory-of-mind network has been associated with making inferences about mental states and underlying character, such as whether someone is friendly, selfish, or generous. To date, however, it is largely unknown how such distinct processing components integrate neural signals. Using functional magnetic resonance imaging and connectivity analyses, we investigated the contribution of functional integration to social perception. During scanning, participants observed bodies that had previously been associated with trait-based or neutral information. Additionally, we independently localised the body perception and theory-of-mind networks. We demonstrate that when observing someone who cues the recall of stored social knowledge compared to non-social knowledge, a node in the ventral visual stream (extrastriate body area) shows greater coupling with part of the theory-of-mind network (temporal pole). These results show that functional connections provide an interface between perceptual and inferential processing components, thus providing neurobiological evidence that supports the view that understanding the visual environment involves interplay between conceptual knowledge and perceptual processing. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Hyporheic Passive Flux Meters Reveal Inverse Vertical Zonation and High Seasonality of Nitrogen Processing in an Anthropogenically Modified Stream (Holtemme, Germany)

NASA Astrophysics Data System (ADS)

Kunz, Julia Vanessa; Annable, Michael D.; Rao, Suresh; Rode, Michael; Borchardt, Dietrich

2017-12-01

Transformation and retention of nitrogen and other biologically reactive solutes in the hyporheic zones of running water contribute to an essential ecosystem service. However, the synoptic impact of intense agricultural or urban land-uses, elevated nutrient loading, flow alterations, riparian clear-cutting, and channelization on the source-sink behavior of solutes in hyporheic zones remains largely uncharacterized and unquantified. Therefore, we studied nutrient dynamics in a hydromorphologically and chemically modified stream reach using a new monitoring approach allowing the simultaneous measurement of nutrient and water flux through a screened area in the subsurface of rivers (hyporheic passive flux meter, HPFM). With HPFMs we directly assessed time-integrated lateral hyporheic nitrate fluxes during early spring and midsummer covering different temperature and discharge regimes. Contrary to our expectations, higher stream discharge coincided with substantially lower hyporheic exchange rates. While in streams featuring a natural morphology, bed form induced exchange commonly increases with surface flow, the influence of groundwater level was dominant in this reach. Furthermore, in contrast to less impacted environments, where progressive substrate depletion with depths reduces metabolic rates in the subsurface, we identified not the upper, but the intermediate layer of the hyporheic zone as hot spot of nutrient turnover. Overall, the hyporheic zone at the study site functioned partly as nitrate source, partly as a sink. Neither of the commonly used determinants redox state and residence time could explain this source or sink function. Our results give clear evidence to carefully transfer the knowledge of hyporheic zone processes from "natural" systems to anthropologically modified streams.

Video Analysis in Multi-Intelligence

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

Key, Everett Kiusan; Van Buren, Kendra Lu; Warren, Will

This is a project which was performed by a graduated high school student at Los Alamos National Laboratory (LANL). The goal of the Multi-intelligence (MINT) project is to determine the state of a facility from multiple data streams. The data streams are indirect observations. The researcher is using DARHT (Dual-Axis Radiographic Hydrodynamic Test Facility) as a proof of concept. In summary, videos from the DARHT facility contain a rich amount of information. Distribution of car activity can inform us about the state of the facility. Counting large vehicles shows promise as another feature for identifying the state of operations. Signalmore » processing techniques are limited by the low resolution and compression of the videos. We are working on integrating these features with features obtained from other data streams to contribute to the MINT project. Future work can pursue other observations, such as when the gate is functioning or non-functioning.« less

The Breakup Mechanism and the Spray Pulsation Behavior of a Three-Stream Atomizer

NASA Astrophysics Data System (ADS)

Ng, Chin; Dord, Anne; Aliseda, Alberto

2011-11-01

In many processes of industrial importance, such as gasification, the liquid to gas mass ratio injected at the atomizer exceeds the limit of conventional two-fluid coaxial atomizers. To maximize the shear rate between the atomization gas and the liquid while maintaining a large contact area, a secondary gas stream is added at the centerline of the spray, interior to the liquid flow, which is annular in this configuration. This cylindrical gas jet has low momentum and does not contribute to the breakup process, which is still dominated by the high shear between the concentric annular liquid flow and the high momentum gas stream. The presence of two independently controlled gas streams leads to the appearance of a hydrodynamic instability that manifests itself in pulsating liquid flow rates and droplet sizes. We study the dependency of the atomization process on the relative flow rates of the three streams. We measure the size distribution, droplet number density and total liquid volumetric flow rate as a function of time, for realistic Weber and Ohnesorge numbers. Analysis of the temporal evolution of these physical variables reveals the dominant frequency of the instability and its effect on the breakup and dispersion of droplets in the spray. We present flow visualization and Phase Doppler Particle Analyzer results that provide insight into the behavior of this complex coaxial shear flow.

Solute transport in streams of varying morphology inferred from a high resolution network of potentiometric wireless chloride sensors

NASA Astrophysics Data System (ADS)

Klaus, Julian; Smettem, Keith; Pfister, Laurent; Harris, Nick

2017-04-01

There is ongoing interest in understanding and quantifying the travel times and dispersion of solutes moving through stream environments, including the hyporheic zone and/or in-channel dead zones where retention affects biogeochemical cycling processes that are critical to stream ecosystem functioning. Modelling these transport and retention processes requires acquisition of tracer data from injection experiments where the concentrations are recorded downstream. Such experiments are often time consuming and costly, which may be the reason many modelling studies of chemical transport have tended to rely on relatively few well documented field case studies. This leads to the need of fast and cheap distributed sensor arrays that respond instantly and record chemical transport at points of interest on timescales of seconds at various locations in the stream environment. To tackle this challenge we present data from several tracer experiments carried out in the Attert river catchment in Luxembourg employing low-cost (in the order of a euro per sensor) potentiometric chloride sensors in a distributed array. We injected NaCl under various baseflow conditions in streams of different morphologies and observed solute transport at various distances and locations. This data is used to benchmark the sensors to data obtained from more expensive electrical conductivity meters. Furthermore, the data allowed spatial resolution of hydrodynamic mixing processes and identification of chemical 'dead zones' in the study reaches.

River restoration: separating myths from reality

NASA Astrophysics Data System (ADS)

Friberg, N.; Woodward, G.

2015-12-01

River restorations are a social construct where degraded systems are physically modified to obtain a pre-disturbance set of attributes. These can be purely esthetic but are often linked to some kind of biotic recovery or the provision of important ecosystem services such as flood control or self-purification. The social setting of restoration projects, with a range of potential conflicts, significantly reduces scale of most interventions to a size with little room, or wish, for natural processes. We show that projects sizes are still very small and that the restoration target is not to recover natural geomorphic processes but rather to fulfil human perception of what a nice stream looks like. One case from Danish lowland streams, using a space-for-time substitution approach, shows excess use of pebble and gravel when restoring channelized sandy bottom streams, de-coupling the link between energy and substrate characteristics that are found in natural lowland systems. This has implication for both the biological structure and functioning of these systems as a direct link between substrate heterogeneity and macroinvertebrate diversity was not found in restored streams, while the density of grazer increased indicating an increased use of periphyton as a basal resource. Another case of adding woody debris to UK lowland streams, using a BACI study design, showed very little effect on the macroinvertebrate community even after a 100-year flood, which indicate that added tree trunks did not provide additional flow refugia. We suggest that restoration schemes should aim at restoring the natural physical structural complexity in the streams and at the same time enhance the possibility of re-generating the natural geomorphological processes sustaining the habitats in streams and rivers.

Freshwater processing of terrestrial dissolved organic matter: What governs lability?

NASA Astrophysics Data System (ADS)

D'Andrilli, J.; Smith, H. J.; Junker, J. R.; Scholl, E. A.; Foreman, C. M.

2016-12-01

Aquatic and terrestrial ecosystems are linked through the transfer of energy and materials. Allochthonous organic matter (OM) is central to freshwater ecosystem function, influencing local food webs, trophic state, and nutrient availability. In order to understand the nature and fate of OM from inland headwaters to the open ocean, it is imperative to understand the links between OM lability and ecosystem function. Thus, biological, chemical, and physical factors need to be evaluated together to inform our understanding of environmental lability. We performed a laboratory processing experiment on naturally occurring OM leachates from riparian leaves, grasses, and pine needles. Measures of water chemistry, OM optical and molecular characterization, bacterial abundances, microbial assemblage composition, respiration, and C:N:P were integrated to discern the nature and fate of labile and recalcitrant OM in a freshwater stream. Peak processing of all OM sources in the stream water occurred after two days, with spikes in bacterial cell abundances, respiration rates, microbial assemblage shifts, and maximum C utilization. Respiration rates and microbial assemblages were dependent on the degree of lability of the OM molecular composition. Within the first few days, no differences in respiration rates were observed between leachate sources, however, beyond day five, the rates diverged with C processing efficiency correlated with OM lability. Originally comprised of amino acid-like, labile fluorescent species, the inoculated stream water OM became more recalcitrant after 16 days, indicating humification processing over time. Our study highlights the importance of interdisciplinary approaches for understanding the processing and fate of OM in aquatic ecosystems.

Distribution and biophysical processes of beaded streams in Arctic permafrost landscapes

NASA Astrophysics Data System (ADS)

Arp, C. D.; Whitman, M. S.; Jones, B. M.; Grosse, G.; Gaglioti, B. V.; Heim, K. C.

2015-01-01

Beaded streams are widespread in permafrost regions and are considered a common thermokarst landform. However, little is known about their distribution, how and under what conditions they form, and how their intriguing morphology translates to ecosystem functions and habitat. Here we report on a circum-Arctic survey of beaded streams and a watershed-scale analysis in northern Alaska using remote sensing and field studies. We mapped over 400 channel networks with beaded morphology throughout the continuous permafrost zone of northern Alaska, Canada, and Russia and found the highest abundance associated with medium to high ground-ice content permafrost in moderately sloping terrain. In one Arctic coastal plain watershed, beaded streams accounted for half of the drainage density, occurring primarily as low-order channels initiating from lakes and drained lake basins. Beaded streams predictably transition to alluvial channels with increasing drainage area and decreasing channel slope, although this transition is modified by local controls on water and sediment delivery. The comparisons of one beaded channel using repeat photography between 1948 and 2013 indicate a relatively stable landform, and 14C dating of basal sediments suggest channel formation may be as early as the Pleistocene-Holocene transition. Contemporary processes, such as deep snow accumulation in riparian zones, effectively insulate channel ice and allows for perennial liquid water below most beaded stream pools. Because of this, mean annual temperatures in pool beds are greater than 2 °C, leading to the development of perennial thaw bulbs or taliks underlying these thermokarst features that range from 0.7 to 1.6 m. In the summer, some pools thermally stratify, which reduces permafrost thaw and maintains cold-water habitats. Snowmelt-generated peak flows decrease rapidly by two or more orders of magnitude to summer low flows with slow reach-scale velocity distributions ranging from 0.01 to 0.1 m s-1, yet channel runs still move water rapidly between pools. The repeating spatial pattern associated with beaded stream morphology and hydrological dynamics may provide abundant and optimal foraging habitat for fish. Beaded streams may create important ecosystem functions and habitat in many permafrost landscapes and their distribution and dynamics are only beginning to be recognized in Arctic research.

Distribution and biophysical processes of beaded streams in Arctic permafrost landscapes

USGS Publications Warehouse

Arp, Christopher D.; Whitman, Matthew S.; Jones, Benjamin M.; Grosse, Guido; Gaglioti, Benjamin V.; Heim, Kurt C.

2015-01-01

Beaded streams are widespread in permafrost regions and are considered a common thermokarst landform. However, little is known about their distribution, how and under what conditions they form, and how their intriguing morphology translates to ecosystem functions and habitat. Here we report on a Circum-Arctic survey of beaded streams and a watershed-scale analysis in northern Alaska using remote sensing and field studies. We mapped over 400 channel networks with beaded morphology throughout the continuous permafrost zone of northern Alaska, Canada, and Russia and found the highest abundance associated with medium- to high- ground ice content permafrost in moderately sloping terrain. In the Fish Creek watershed, beaded streams accounted for half of the drainage density, occurring primarily as low-order channels initiating from lakes and drained lake basins. Beaded streams predictably transition to alluvial channels with increasing drainage area and decreasing channel slope, although this transition is modified by local controls on water and sediment delivery. Comparison of one beaded channel using repeat photography between 1948 and 2013 indicate a relatively stable landform and 14C dating of basal sediments suggest channel formation may be as early as the Pleistocene-Holocene transition. Contemporary processes, such as deep snow accumulation in riparian zones effectively insulates channel ice and allows for perennial liquid water below most beaded stream pools. Because of this, mean annual temperatures in pool beds are greater than 2°C, leading to the development of perennial thaw bulbs or taliks underlying these thermokarst features. In the summer, some pools thermally stratify, which reduces permafrost thaw and maintains coldwater habitats. Snowmelt generated peak-flows decrease rapidly by two or more orders of magnitude to summer low flows with slow reach-scale velocity distributions ranging from 0.1 to 0.01 m/s, yet channel runs still move water rapidly between pools. The repeating spatial pattern associated with beaded stream morphology and hydrological dynamics may provide abundant and optimal foraging habitat for fish. Thus, beaded streams may create important ecosystem functions and habitat in many permafrost landscapes and their distribution and dynamics are only beginning to be recognized in Arctic research.

Apparatus for the liquefaction of natural gas and methods relating to same

DOEpatents

Wilding, Bruce M [Idaho Falls, ID; McKellar, Michael G [Idaho Falls, ID; Turner, Terry D [Ammon, ID; Carney, Francis H [Idaho Falls, ID

2009-09-29

An apparatus and method for producing liquefied natural gas. A liquefaction plant may be coupled to a source of unpurified natural gas, such as a natural gas pipeline at a pressure letdown station. A portion of the gas is drawn off and split into a process stream and a cooling stream. The cooling stream passes through an expander creating work output. A compressor may be driven by the work output and compresses the process stream. The compressed process stream is cooled, such as by the expanded cooling stream. The cooled, compressed process stream is divided into first and second portions with the first portion being expanded to liquefy the natural gas. A gas-liquid separator separates the vapor from the liquid natural gas. The second portion of the cooled, compressed process stream is also expanded and used to cool the compressed process stream.

Methods of natural gas liquefaction and natural gas liquefaction plants utilizing multiple and varying gas streams

DOEpatents

Wilding, Bruce M; Turner, Terry D

2014-12-02

A method of natural gas liquefaction may include cooling a gaseous NG process stream to form a liquid NG process stream. The method may further include directing the first tail gas stream out of a plant at a first pressure and directing a second tail gas stream out of the plant at a second pressure. An additional method of natural gas liquefaction may include separating CO.sub.2 from a liquid NG process stream and processing the CO.sub.2 to provide a CO.sub.2 product stream. Another method of natural gas liquefaction may include combining a marginal gaseous NG process stream with a secondary substantially pure NG stream to provide an improved gaseous NG process stream. Additionally, a NG liquefaction plant may include a first tail gas outlet, and at least a second tail gas outlet, the at least a second tail gas outlet separate from the first tail gas outlet.

Modeling the dynamics of metabolism in montane streams using continuous dissolved oxygen measurements

NASA Astrophysics Data System (ADS)

Birkel, Christian; Soulsby, Chris; Malcolm, Iain; Tetzlaff, Doerthe

2013-09-01

We inferred in-stream ecosystem processes in terms of photosynthetic productivity (P), system respiration (R), and reaeration capacity (RC) from a five parameter numerical oxygen mass balance model driven by radiation, stream and air temperature, and stream depth. This was calibrated to high-resolution (15 min), long-term (2.5 years) dissolved oxygen (DO) time series for moorland and forest reaches of a third-order montane stream in Scotland. The model was multicriteria calibrated to continuous 24 h periods within the time series to identify behavioral simulations representative of ecosystem functioning. Results were evaluated using a seasonal regional sensitivity analysis and a colinearity index for parameter sensitivity. This showed that >95 % of the behavioral models for the moorland and forest sites were identifiable and able to infer in-stream processes from the DO time series for around 40% and 32% of the time period, respectively. Monthly P/R ratios <1 indicate a heterotrophic system with both sites exhibiting similar temporal patterns; with a maximum in February and a second peak during summer months. However, the estimated net ecosystem productivity suggests that the moorland reach without riparian tree cover is likely to be a much larger source of carbon to the atmosphere (122 mmol C m-2 d-1) compared to the forested reach (64 mmol C m-2 d-1). We conclude that such process-based oxygen mass balance models may be transferable tools for investigating other systems; specifically, well-oxygenated upland channels with high hydraulic roughness and lacking reaeration measurements.

Apparatus for the liquefaction of natural gas and methods relating to same

DOEpatents

Wilding, Bruce M [Idaho Falls, ID; Bingham, Dennis N [Idaho Falls, ID; McKellar, Michael G [Idaho Falls, ID; Turner, Terry D [Ammon, ID; Raterman, Kevin T [Idaho Falls, ID; Palmer, Gary L [Shelley, ID; Klingler, Kerry M [Idaho Falls, ID; Vranicar, John J [Concord, CA

2007-05-22

An apparatus and method for producing liquefied natural gas. A liquefaction plant may be coupled to a source of unpurified natural gas, such as a natural gas pipeline at a pressure letdown station. A portion of the gas is drawn off and split into a process stream and a cooling stream. The cooling stream passes through a turbo expander creating work output. A compressor is driven by the work output and compresses the process stream. The compressed process stream is cooled, such as by the expanded cooling stream. The cooled, compressed process stream is divided into first and second portions with the first portion being expanded to liquefy the natural gas. A gas-liquid separator separates the vapor from the liquid natural gas. The second portion of the cooled, compressed process stream is also expanded and used to cool the compressed process stream. Additional features and techniques may be integrated with the liquefaction process including a water clean-up cycle and a carbon dioxide (CO.sub.2) clean-up cycle.

Apparatus For The Liquefaaction Of Natural Gas And Methods Relating To Same

DOEpatents

Wilding, Bruce M.; Bingham, Dennis N.; McKellar, Michael G.; Turner, Terry D.; Rateman, Kevin T.; Palmer, Gary L.; Klinger, Kerry M.; Vranicar, John J.

2005-11-08

An apparatus and method for producing liquefied natural gas. A liquefaction plant may be coupled to a source of unpurified natural gas, such as a natural gas pipeline at a pressure letdown station. A portion of the gas is drawn off and split into a process stream and a cooling stream. The cooling stream passes through a turbo expander creating work output. A compressor is driven by the work output and compresses the process stream. The compressed process stream is cooled, such as by the expanded cooling stream. The cooled, compressed process stream is divided into first and second portions with the first portion being expanded to liquefy the natural gas. A gas-liquid separator separates the vapor from the liquid natural gas. The second portion of the cooled, compressed process stream is also expanded and used to cool the compressed process stream. Additional features and techniques may be integrated with the liquefaction process including a water clean-up cycle and a carbon dioxide (CO2) clean-up cycle.

Apparatus For The Liquefaaction Of Natural Gas And Methods Relating To Same

DOEpatents

Wilding, Bruce M.; Bingham, Dennis N.; McKellar, Michael G.; Turner, Terry D.; Raterman, Kevin T.; Palmer, Gary L.; Klingler, Kerry M.; Vranicar, John J.

2005-05-03

An apparatus and method for producing liquefied natural gas. A liquefaction plant may be coupled to a source of unpurified natural gas, such as a natural gas pipeline at a pressure letdown station. A portion of the gas is drawn off and split into a process stream and a cooling stream. The cooling stream passes through a turbo expander creating work output. A compressor is driven by the work output and compresses the process stream. The compressed process stream is cooled, such as by the expanded cooling stream. The cooled, compressed process stream is divided into first and second portions with the first portion being expanded to liquefy the natural gas. A gas-liquid separator separates the vapor from the liquid natural gas. The second portion of the cooled, compressed process stream is also expanded and used to cool the compressed process stream. Additional features and techniques may be integrated with the liquefaction process including a water clean-up cycle and a carbon dioxide (CO2) clean-up cycle.

Apparatus For The Liquefaaction Of Natural Gas And Methods Relating To Same

DOEpatents

Wilding, Bruce M.; Bingham, Dennis N.; McKellar, Michael G.; Turner, Terry D.; Raterman, Kevin T.; Palmer, Gary L.; Klingler, Kerry M.; Vranicar, John J.

2003-06-24

An apparatus and method for producing liquefied natural gas. A liquefaction plant may be coupled to a source of unpurified natural gas, such as a natural gas pipeline at a pressure letdown station. A portion of the gas is drawn off and split into a process stream and a cooling stream. The cooling stream passes through a turbo expander creating work output. A compressor is driven by the work output and compresses the process stream. The compressed process stream is cooled, such as by the expanded cooling stream. The cooled, compressed process stream is divided into first and second portions with the first portion being expanded to liquefy the natural gas. A gas-liquid separator separates the vapor from the liquid natural gas. The second portion of the cooled, compressed process stream is also expanded and used to cool the compressed process stream. Additional features and techniques may be integrated with the liquefaction process including a water clean-up cycle and a carbon dioxide (CO.sub.2) clean-up cycle.

Optic ataxia and the function of the dorsal stream: contributions to perception and action.

PubMed

Pisella, Laure; Sergio, Lauren; Blangero, Annabelle; Torchin, Héloïse; Vighetto, Alain; Rossetti, Yves

2009-12-01

Optic ataxia (OA) is one of the symptoms pertaining to Bálint's Syndrome. It has been described clinically for nearly 80 years before it became a cornerstone of the most popular dual stream theory of the visual brain. Over the last 10 years a regain of interest for this neurological condition lead to a number of precise analyses of the deficits found in optic ataxia, giving rise to a renewed outline of its very definition and hence of the function(s) of the occipito-parietal (dorsal) stream. In absence of concomitant clinical symptoms, we review evidence that misreaching errors in central vision result from the "hand effect": an erroneous dynamic spatial processing of proprioceptive information from the hand. When visual feedback of the hand is provided (closed-loop condition), pure optic ataxia is restricted to peripheral vision. This central versus peripheral vision distinction is repeatedly used to argue that action and perception are not unique and dissociated systems. New assessments of optic ataxia patients are provided, confirming on one hand that their visuomotor deficit is specific to peripheral vision (i.e. when the gaze and the hand goals are dissociated), on the other hand that they disclose perceptual deficits in peripheral vision. These results are coherent with the recent demonstration that optic ataxia patients exhibit a general contralesional deficit for dynamic visuo-spatial processing, affecting both hand and eye movements [Gaveau, V., Pélisson, D., Blangero, A., Urquizar, C., Prablanc, C.,Vighetto, A., et al. (2008). A common parietal module for saccade and reach: Eye-hand coordination and saccadic control in optic ataxia. Neuropsychologia, 46, 475-486]. Such module(s) within the dorsal stream could be used for both action and perception in the periphery. It is concluded that optic ataxia cannot be considered as a unitary and specific visuo-manual deficit, and that the modular organisation of the dorsal stream allows for numerous dorsal-ventral interactions for perception and action.

Hydrolysis and fractionation of lignocellulosic biomass

DOEpatents

Torget, Robert W.; Padukone, Nandan; Hatzis, Christos; Wyman, Charles E.

2000-01-01

A multi-function process is described for the hydrolysis and fractionation of lignocellulosic biomass to separate hemicellulosic sugars from other biomass components such as extractives and proteins; a portion of the solubilized lignin; cellulose; glucose derived from cellulose; and insoluble lignin from said biomass comprising one or more of the following: optionally, as function 1, introducing a dilute acid of pH 1.0-5.0 into a continual shrinking bed reactor containing a lignocellulosic biomass material at a temperature of about 94 to about 160.degree. C. for a period of about 10 to about 120 minutes at a volumetric flow rate of about 1 to about 5 reactor volumes to effect solubilization of extractives, lignin, and protein by keeping the solid to liquid ratio constant throughout the solubilization process; as function 2, introducing a dilute acid of pH 1.0-5.0, either as virgin acid or an acidic stream from another function, into a continual shrinking bed reactor containing either fresh biomass or the partially fractionated lignocellulosic biomass material from function 1 at a temperature of about 94-220.degree. C. for a period of about 10 to about 60 minutes at a volumetric flow rate of about 1 to about 5 reactor volumes to effect solubilization of hemicellulosic sugars, semisoluble sugars and other compounds, and amorphous glucans by keeping the solid to liquid ratio constant throughout the solubilization process; as function 3, optionally, introducing a dilute acid of pH 1.0-5.0 either as virgin acid or an acidic stream from another function, into a continual shrinking bed reactor containing the partially fractionated lignocellulosic biomass material from function 2 at a temperature of about 180-280.degree. C. for a period of about 10 to about 60 minutes at a volumetric flow rate of 1 to about 5 reactor volumes to effect solubilization of cellulosic sugars by keeping the solid to liquid ratio constant throughout the solubilization process; and as function 4, optionally, introducing a dilute acid of pH 1.0-5.0 either as virgin acid or an acidic stream from another function, into a continual shrinking bed reactor containing the partially fractionated lignocellulosic biomass material from function 3 at a temperature of about 180-280.degree. C. for a period of about 10 to about 60 minutes at a volumetric flow rate of about 1 to about 5 reactor volumes to effect solubilization of cellulosic sugars by keeping the solid to liquid ratio constant throughout the solubilization process.

Removal of hydrogen sulfide as ammonium sulfate from hydropyrolysis product vapors

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

Marker, Terry L.; Felix, Larry G.; Linck, Martin B.

A system and method for processing biomass into hydrocarbon fuels that includes processing a biomass in a hydropyrolysis reactor resulting in hydrocarbon fuels and a process vapor stream and cooling the process vapor stream to a condensation temperature resulting in an aqueous stream. The aqueous stream is sent to a catalytic reactor where it is oxidized to obtain a product stream containing ammonia and ammonium sulfate. A resulting cooled product vapor stream includes non-condensable process vapors comprising H.sub.2, CH.sub.4, CO, CO.sub.2, ammonia and hydrogen sulfide.

Removal of hydrogen sulfide as ammonium sulfate from hydropyrolysis product vapors

DOEpatents

Marker, Terry L; Felix, Larry G; Linck, Martin B; Roberts, Michael J

2014-10-14

A system and method for processing biomass into hydrocarbon fuels that includes processing a biomass in a hydropyrolysis reactor resulting in hydrocarbon fuels and a process vapor stream and cooling the process vapor stream to a condensation temperature resulting in an aqueous stream. The aqueous stream is sent to a catalytic reactor where it is oxidized to obtain a product stream containing ammonia and ammonium sulfate. A resulting cooled product vapor stream includes non-condensable process vapors comprising H.sub.2, CH.sub.4, CO, CO.sub.2, ammonia and hydrogen sulfide.

Prioritized Contact Transport Stream

NASA Technical Reports Server (NTRS)

Hunt, Walter Lee, Jr. (Inventor)

2015-01-01

A detection process, contact recognition process, classification process, and identification process are applied to raw sensor data to produce an identified contact record set containing one or more identified contact records. A prioritization process is applied to the identified contact record set to assign a contact priority to each contact record in the identified contact record set. Data are removed from the contact records in the identified contact record set based on the contact priorities assigned to those contact records. A first contact stream is produced from the resulting contact records. The first contact stream is streamed in a contact transport stream. The contact transport stream may include and stream additional contact streams. The contact transport stream may be varied dynamically over time based on parameters such as available bandwidth, contact priority, presence/absence of contacts, system state, and configuration parameters.

Smelling directions: Olfaction modulates ambiguous visual motion perception

PubMed Central

Kuang, Shenbing; Zhang, Tao

2014-01-01

Senses of smells are often accompanied by simultaneous visual sensations. Previous studies have documented enhanced olfactory performance with concurrent presence of congruent color- or shape- related visual cues, and facilitated visual object perception when congruent smells are simultaneously present. These visual object-olfaction interactions suggest the existences of couplings between the olfactory pathway and the visual ventral processing stream. However, it is not known if olfaction can modulate visual motion perception, a function that is related to the visual dorsal stream. We tested this possibility by examining the influence of olfactory cues on the perceptions of ambiguous visual motion signals. We showed that, after introducing an association between motion directions and olfactory cues, olfaction could indeed bias ambiguous visual motion perceptions. Our result that olfaction modulates visual motion processing adds to the current knowledge of cross-modal interactions and implies a possible functional linkage between the olfactory system and the visual dorsal pathway. PMID:25052162

Exploring the impact of agriculture on nitrogen and phosphorus biogeochemistry in global rivers during the twentieth century (Invited)

NASA Astrophysics Data System (ADS)

Bouwman, L.; Beusen, A.; Van Beek, L. P.

2013-12-01

Nutrients are transported from land to sea through the continuum formed by soils, groundwater, riparian zones, floodplains, streams, rivers, lakes, and reservoirs. The hydrology, ecology and biogeochemical processing in each of these components are strongly coupled and result in retention of a significant fraction of the nutrients transported. This paper analyzes the global changes in nutrient biogeochemical processes and retention in rivers during the past century (1900-2000); this period encompasses dramatic increases in human population and economic human activities including agriculture that have resulted in major changes in land use, nutrient use in agriculture, wastewater flows and human interventions in the hydrology (1). We use the hydrological PCR-GLOBWB model (2) for the period 1900-2000, including climate variability and the history of dam construction and land use conversion. Global agricultural and natural N and P soil budgets for the period 1900-2000 are the starting point to simulate nutrient flows from the soil via surface runoff and leaching through the groundwater system and riparian zones. In-stream processes are described with the nutrient spiraling concept. In the period 1900-2000, the global soil N budget surplus (inputs minus withdrawal in harvested crops) for agricultural and natural ecosystems increased from 118 to 202 Tg yr-1, and the global P budget increased from < 0.5 to 11 Tg P yr-1. As a result of this massive increase, nutrient delivery to streams and river nutrient export has increased rapidly in the 20th century. Model results are sensitive to factors determining the N and P delivery, as well as in-stream processes. The most uncertain factors are N delivery to streams by groundwater (denitrification as a function of thickness and reactivity of aquifers), and in-stream N and P retention parameters (net uptake velocity, retention as function of concentration). References 1. Bouwman AF, Beusen AHW, Griffioen J, Van Groenigen JW, Hefting MM, Oenema O, et al. Global trends and uncertainties in terrestrial denitrification and N2O emissions. Philosophical Transactions of the Royal Society B: Biological Sciences. 2013;368(20130112). 2. Van Beek LPH, Wada Y, Bierkens MFP. Global monthly water stress: 1. Water balance and water availability. Water Resour Res. 2011;47(7):W07517.

Dorsal and ventral stream contributions to form-from-motion perception in a patient with form-from motion deficit: a case report.

PubMed

Mercier, Manuel R; Schwartz, Sophie; Spinelli, Laurent; Michel, Christoph M; Blanke, Olaf

2017-03-01

The main model of visual processing in primates proposes an anatomo-functional distinction between the dorsal stream, specialized in spatio-temporal information, and the ventral stream, processing essentially form information. However, these two pathways also communicate to share much visual information. These dorso-ventral interactions have been studied using form-from-motion (FfM) stimuli, revealing that FfM perception first activates dorsal regions (e.g., MT+/V5), followed by successive activations of ventral regions (e.g., LOC). However, relatively little is known about the implications of focal brain damage of visual areas on these dorso-ventral interactions. In the present case report, we investigated the dynamics of dorsal and ventral activations related to FfM perception (using topographical ERP analysis and electrical source imaging) in a patient suffering from a deficit in FfM perception due to right extrastriate brain damage in the ventral stream. Despite the patient's FfM impairment, both successful (observed for the highest level of FfM signal) and absent/failed FfM perception evoked the same temporal sequence of three processing states observed previously in healthy subjects. During the first period, brain source localization revealed cortical activations along the dorsal stream, currently associated with preserved elementary motion processing. During the latter two periods, the patterns of activity differed from normal subjects: activations were observed in the ventral stream (as reported for normal subjects), but also in the dorsal pathway, with the strongest and most sustained activity localized in the parieto-occipital regions. On the other hand, absent/failed FfM perception was characterized by weaker brain activity, restricted to the more lateral regions. This study shows that in the present case report, successful FfM perception, while following the same temporal sequence of processing steps as in normal subjects, evoked different patterns of brain activity. By revealing a brain circuit involving the most rostral part of the dorsal pathway, this study provides further support for neuro-imaging studies and brain lesion investigations that have suggested the existence of different brain circuits associated with different profiles of interaction between the dorsal and the ventral streams.

Incorporating ecogeomorphic feedbacks to better understand resiliency in streams: A review and directions forward

NASA Astrophysics Data System (ADS)

Atkinson, Carla L.; Allen, Daniel C.; Davis, Lisa; Nickerson, Zachary L.

2018-03-01

Decades of interdisciplinary research show river form and function depends on interactions between the living and nonliving world, but a dominant paradigm underlying ecogeomorphic work consists of a top-down, unidirectional approach with abiotic forces driving biotic systems. Stream form and location within the stream network does dictate the habitat and resources available for organisms and overall community structure. Yet this traditional hierarchal framework on its own is inadequate in communicating information regarding the influence of biological systems on fluvial geomorphology that lead to changes in channel morphology, sediment cycling, and system-scale functions (e.g., sediment yield, biogeochemical nutrient cycling). Substantial evidence that organisms influence fluvial geomorphology exists, specifically the ability of aquatic vegetation and lotic animals to modify flow velocities and sediment deposition and transport - thus challenging the traditional hierarchal framework. Researchers recognize the need for ecogeomorphic frameworks that conceptualize feedbacks between organisms, sediment transport, and geomorphic structure. Furthermore, vital ecosystem processes, such as biogeochemical nutrient cycling represent the conversations that are occurring between geomorphological and biological systems. Here we review and synthesize selected case studies highlighting the role organisms play in moderating geomorphic processes and likely interact with these processes to have an impact on an essential ecosystem process, biogeochemical nutrient recycling. We explore whether biophysical interactions can provide information essential to improving predictions of system-scale river functions, specifically sediment transport and biogeochemical cycling, and discuss tools used to study these interactions. We suggest that current conceptual frameworks should acknowledge that hydrologic, geomorphologic, and ecologic processes operate on different temporal scales, generating bidirectional feedback loops over space and time. Hydro- and geomorphologic processes, operating episodically during bankfull conditions, influence ecological processes (e.g., biogeochemical cycling) occurring over longer time periods during base-flow conditions. This ecological activity generates the antecedent conditions that influence the hydro- and geomorphologic processes occurring during the next high flow event, creating a bidirectional feedback. This feedback should enhance the resiliency of fluvial landforms and ecosystem processes, allowing physical and biological processes to pull and push against each other over time.

Evaluating Indicators and Life Cycle Inventories for Processes in Early Stages of Technical Readiness

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

Tan, Eric C; Smith, Raymond; Ruiz-Mercado, Gerardo

This presentation examines different methods for analyzing manufacturing processes in the early stages of technical readiness. Before developers know much detail about their processes, it is valuable to apply various assessments to evaluate their performance. One type of assessment evaluates performance indicators to describe how closely processes approach desirable objectives. Another type of assessment determines the life cycle inventories (LCI) of inputs and outputs for processes, where for a functional unit of product, the user evaluates the resources used and the releases to the environment. These results can be compared to similar processes or combined with the LCI of othermore » processes to examine up-and down-stream chemicals. The inventory also provides a listing of the up-stream chemicals, which permits study of the whole life cycle. Performance indicators are evaluated in this presentation with the U.S. Environmental Protection Agency's GREENSCOPE (Gauging Reaction Effectiveness for ENvironmental Sustainability with a multi-Objective Process Evaluator) methodology, which evaluates processes in four areas: Environment, Energy, Economics, and Efficiency. The method develops relative scores for indicators that allow comparisons across various technologies. In this contribution, two conversion pathways for producing cellulosic ethanol from biomass, via thermochemical and biochemical routes, are studied. The information developed from the indicators and LCI can be used to inform the process design and the potential life cycle effects of up- and down-stream chemicals.« less

A rapid method to score stream reaches based on the overall performance of their main ecological functions.

PubMed

Rowe, David K; Parkyn, Stephanie; Quinn, John; Collier, Kevin; Hatton, Chris; Joy, Michael K; Maxted, John; Moore, Stephen

2009-06-01

A method was developed to score the ecological condition of first- to third-order stream reaches in the Auckland region of New Zealand based on the performance of their key ecological functions. Such a method is required by consultants and resource managers to quantify the reduction in ecological condition of a modified stream reach relative to its unmodified state. This is a fundamental precursor for the determination of fair environmental compensation for achieving no-net-loss in overall stream ecological value. Field testing and subsequent use of the method indicated that it provides a useful measure of ecological condition related to the performance of stream ecological functions. It is relatively simple to apply compared to a full ecological study, is quick to use, and allows identification of the degree of impairment of each of the key ecological functions. The scoring system was designed so that future improvements in the measurement of stream functions can be incorporated into it. Although the methodology was specifically designed for Auckland streams, the principles can be readily adapted to other regions and stream types.

Feature integration and object representations along the dorsal stream visual hierarchy

PubMed Central

Perry, Carolyn Jeane; Fallah, Mazyar

2014-01-01

The visual system is split into two processing streams: a ventral stream that receives color and form information and a dorsal stream that receives motion information. Each stream processes that information hierarchically, with each stage building upon the previous. In the ventral stream this leads to the formation of object representations that ultimately allow for object recognition regardless of changes in the surrounding environment. In the dorsal stream, this hierarchical processing has classically been thought to lead to the computation of complex motion in three dimensions. However, there is evidence to suggest that there is integration of both dorsal and ventral stream information into motion computation processes, giving rise to intermediate object representations, which facilitate object selection and decision making mechanisms in the dorsal stream. First we review the hierarchical processing of motion along the dorsal stream and the building up of object representations along the ventral stream. Then we discuss recent work on the integration of ventral and dorsal stream features that lead to intermediate object representations in the dorsal stream. Finally we propose a framework describing how and at what stage different features are integrated into dorsal visual stream object representations. Determining the integration of features along the dorsal stream is necessary to understand not only how the dorsal stream builds up an object representation but also which computations are performed on object representations instead of local features. PMID:25140147

StreamStats in North Carolina: a water-resources Web application

USGS Publications Warehouse

Weaver, J. Curtis; Terziotti, Silvia; Kolb, Katharine R.; Wagner, Chad R.

2012-01-01

A statewide StreamStats application for North Carolina was developed in cooperation with the North Carolina Department of Transportation following completion of a pilot application for the upper French Broad River basin in western North Carolina (Wagner and others, 2009). StreamStats for North Carolina, available at http://water.usgs.gov/osw/streamstats/north_carolina.html, is a Web-based Geographic Information System (GIS) application developed by the U.S. Geological Survey (USGS) in consultation with Environmental Systems Research Institute, Inc. (Esri) to provide access to an assortment of analytical tools that are useful for water-resources planning and management (Ries and others, 2008). The StreamStats application provides an accurate and consistent process that allows users to easily obtain streamflow statistics, basin characteristics, and descriptive information for USGS data-collection sites and user-selected ungaged sites. In the North Carolina application, users can compute 47 basin characteristics and peak-flow frequency statistics (Weaver and others, 2009; Robbins and Pope, 1996) for a delineated drainage basin. Selected streamflow statistics and basin characteristics for data-collection sites have been compiled from published reports and also are immediately accessible by querying individual sites from the web interface. Examples of basin characteristics that can be computed in StreamStats include drainage area, stream slope, mean annual precipitation, and percentage of forested area (Ries and others, 2008). Examples of streamflow statistics that were previously available only through published documents include peak-flow frequency, flow-duration, and precipitation data. These data are valuable for making decisions related to bridge design, floodplain delineation, water-supply permitting, and sustainable stream quality and ecology. The StreamStats application also allows users to identify stream reaches upstream and downstream from user-selected sites and obtain information for locations along streams where activities occur that may affect streamflow conditions. This functionality can be accessed through a map-based interface with the user’s Web browser, or individual functions can be requested remotely through Web services (Ries and others, 2008).

Environmental Control on Microbial Turnover of Leaf Carbon in Streams – Ecological Function of Phototrophic-Heterotrophic Interactions

PubMed Central

Fabian, Jenny; Zlatanović, Sanja; Mutz, Michael; Grossart, Hans-Peter; van Geldern, Robert; Ulrich, Andreas; Gleixner, Gerd; Premke, Katrin

2018-01-01

In aquatic ecosystems, light availability can significantly influence microbial turnover of terrestrial organic matter through associated metabolic interactions between phototrophic and heterotrophic communities. However, particularly in streams, microbial functions vary significantly with the structure of the streambed, that is the distribution and spatial arrangement of sediment grains in the streambed. It is therefore essential to elucidate how environmental factors synergistically define the microbial turnover of terrestrial organic matter in order to better understand the ecological role of photo-heterotrophic interactions in stream ecosystem processes. In outdoor experimental streams, we examined how the structure of streambeds modifies the influence of light availability on microbial turnover of leaf carbon (C). Furthermore, we investigated whether the studied relationships of microbial leaf C turnover to environmental conditions are affected by flow intermittency commonly occurring in streams. We applied leaves enriched with a 13C-stable isotope tracer and combined quantitative and isotope analyses. We thereby elucidated whether treatment induced changes in C turnover were associated with altered use of leaf C within the microbial food web. Moreover, isotope analyses were combined with measurements of microbial community composition to determine whether changes in community function were associated with a change in community composition. In this study, we present evidence, that environmental factors interactively determine how phototrophs and heterotrophs contribute to leaf C turnover. Light availability promoted the utilization of leaf C within the microbial food web, which was likely associated with a promoted availability of highly bioavailable metabolites of phototrophic origin. However, our results additionally confirm that the structure of the streambed modifies light-related changes in microbial C turnover. From our observations, we conclude that the streambed structure influences the strength of photo-heterotrophic interactions by defining the spatial availability of algal metabolites in the streambed and the composition of microbial communities. Collectively, our multifactorial approach provides valuable insights into environmental controls on the functioning of stream ecosystems.

The science and practice of river restoration

NASA Astrophysics Data System (ADS)

Wohl, Ellen; Lane, Stuart N.; Wilcox, Andrew C.

2015-08-01

River restoration is one of the most prominent areas of applied water-resources science. From an initial focus on enhancing fish habitat or river appearance, primarily through structural modification of channel form, restoration has expanded to incorporate a wide variety of management activities designed to enhance river process and form. Restoration is conducted on headwater streams, large lowland rivers, and entire river networks in urban, agricultural, and less intensively human-altered environments. We critically examine how contemporary practitioners approach river restoration and challenges for implementing restoration, which include clearly identified objectives, holistic understanding of rivers as ecosystems, and the role of restoration as a social process. We also examine challenges for scientific understanding in river restoration. These include: how physical complexity supports biogeochemical function, stream metabolism, and stream ecosystem productivity; characterizing response curves of different river components; understanding sediment dynamics; and increasing appreciation of the importance of incorporating climate change considerations and resiliency into restoration planning. Finally, we examine changes in river restoration within the past decade, such as increasing use of stream mitigation banking; development of new tools and technologies; different types of process-based restoration; growing recognition of the importance of biological-physical feedbacks in rivers; increasing expectations of water quality improvements from restoration; and more effective communication between practitioners and river scientists.

Streaming current for particle-covered surfaces: simulations and experiments

NASA Astrophysics Data System (ADS)

Blawzdziewicz, Jerzy; Adamczyk, Zbigniew; Ekiel-Jezewska, Maria L.

2017-11-01

Developing in situ methods for assessment of surface coverage by adsorbed nanoparticles is crucial for numerous technological processes, including controlling protein deposition and fabricating diverse microstructured materials (e.g., antibacterial coatings, catalytic surfaces, and particle-based optical systems). For charged surfaces and particles, promising techniques for evaluating surface coverage are based on measurements of the electrokinetic streaming current associated with ion convection in the double-layer region. We have investigated the dependence of the streaming current on the area fraction of adsorbed particles for equilibrium and random-sequential-adsorption (RSA) distributions of spherical particles, and for periodic square and hexagonal sphere arrays. The RSA results have been verified experimentally. Our numerical results indicate that the streaming current weakly depends on the microstructure of the particle monolayer. Combining simulations with the virial expansion, we provide convenient fitting formulas for the particle and surface contributions to the streaming current as functions of area fractions. For particles that have the same ζ-potential as the surface, we find that surface roughness reduces the streaming current. Supported by NSF Award No. 1603627.

Neural Integration in Body Perception.

PubMed

Ramsey, Richard

2018-06-19

The perception of other people is instrumental in guiding social interactions. For example, the appearance of the human body cues a wide range of inferences regarding sex, age, health, and personality, as well as emotional state and intentions, which influence social behavior. To date, most neuroscience research on body perception has aimed to characterize the functional contribution of segregated patches of cortex in the ventral visual stream. In light of the growing prominence of network architectures in neuroscience, the current article reviews neuroimaging studies that measure functional integration between different brain regions during body perception. The review demonstrates that body perception is not restricted to processing in the ventral visual stream but instead reflects a functional alliance between the ventral visual stream and extended neural systems associated with action perception, executive functions, and theory of mind. Overall, these findings demonstrate how body percepts are constructed through interactions in distributed brain networks and underscore that functional segregation and integration should be considered together when formulating neurocognitive theories of body perception. Insight from such an updated model of body perception generalizes to inform the organizational structure of social perception and cognition more generally and also informs disorders of body image, such as anorexia nervosa, which may rely on atypical integration of body-related information.

Large-scale structure perturbation theory without losing stream crossing

DOE PAGES

McDonald, Patrick; Vlah, Zvonimir

2018-01-10

Here, we suggest an approach to perturbative calculations of large-scale clustering in the Universe that includes from the start the stream crossing (multiple velocities for mass elements at a single position) that is lost in traditional calculations. Starting from a functional integral over displacement, the perturbative series expansion is in deviations from (truncated) Zel’dovich evolution, with terms that can be computed exactly even for stream-crossed displacements. We evaluate the one-loop formulas for displacement and density power spectra numerically in 1D, finding dramatic improvement in agreement with N-body simulations compared to the Zel’dovich power spectrum (which is exact in 1D upmore » to stream crossing). Beyond 1D, our approach could represent an improvement over previous expansions even aside from the inclusion of stream crossing, but we have not investigated this numerically. In the process we show how to achieve effective-theory-like regulation of small-scale fluctuations without free parameters.« less

Large-scale structure perturbation theory without losing stream crossing

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

McDonald, Patrick; Vlah, Zvonimir

Here, we suggest an approach to perturbative calculations of large-scale clustering in the Universe that includes from the start the stream crossing (multiple velocities for mass elements at a single position) that is lost in traditional calculations. Starting from a functional integral over displacement, the perturbative series expansion is in deviations from (truncated) Zel’dovich evolution, with terms that can be computed exactly even for stream-crossed displacements. We evaluate the one-loop formulas for displacement and density power spectra numerically in 1D, finding dramatic improvement in agreement with N-body simulations compared to the Zel’dovich power spectrum (which is exact in 1D upmore » to stream crossing). Beyond 1D, our approach could represent an improvement over previous expansions even aside from the inclusion of stream crossing, but we have not investigated this numerically. In the process we show how to achieve effective-theory-like regulation of small-scale fluctuations without free parameters.« less

Device for staged carbon monoxide oxidation

DOEpatents

Vanderborgh, Nicholas E.; Nguyen, Trung V.; Guante, Jr., Joseph

1993-01-01

A method and apparatus for selectively oxidizing carbon monoxide in a hydrogen rich feed stream. The method comprises mixing a feed stream consisting essentially of hydrogen, carbon dioxide, water and carbon monoxide with a first predetermined quantity of oxygen (air). The temperature of the mixed feed/oxygen stream is adjusted in a first the heat exchanger assembly (20) to a first temperature. The mixed feed/oxygen stream is sent to reaction chambers (30,32) having an oxidation catalyst contained therein. The carbon monoxide of the feed stream preferentially absorbs on the catalyst at the first temperature to react with the oxygen in the chambers (30,32) with minimal simultaneous reaction of the hydrogen to form an intermediate hydrogen rich process stream having a lower carbon monoxide content than the feed stream. The elevated outlet temperature of the process stream is carefully controlled in a second heat exchanger assembly (42) to a second temperature above the first temperature. The process stream is then mixed with a second predetermined quantity of oxygen (air). The carbon monoxide of the process stream preferentially reacts with the second quantity of oxygen in a second stage reaction chamber (56) with minimal simultaneous reaction of the hydrogen in the process stream. The reaction produces a hydrogen rich product stream having a lower carbon monoxide content than the process stream. The product stream is then cooled in a third heat exchanger assembly (72) to a third predetermined temperature. Three or more stages may be desirable, each with metered oxygen injection.

Complementary fMRI and EEG evidence for more efficient neural processing of rhythmic vs. unpredictably timed sounds

PubMed Central

van Atteveldt, Nienke; Musacchia, Gabriella; Zion-Golumbic, Elana; Sehatpour, Pejman; Javitt, Daniel C.; Schroeder, Charles

2015-01-01

The brain’s fascinating ability to adapt its internal neural dynamics to the temporal structure of the sensory environment is becoming increasingly clear. It is thought to be metabolically beneficial to align ongoing oscillatory activity to the relevant inputs in a predictable stream, so that they will enter at optimal processing phases of the spontaneously occurring rhythmic excitability fluctuations. However, some contexts have a more predictable temporal structure than others. Here, we tested the hypothesis that the processing of rhythmic sounds is more efficient than the processing of irregularly timed sounds. To do this, we simultaneously measured functional magnetic resonance imaging (fMRI) and electro-encephalograms (EEG) while participants detected oddball target sounds in alternating blocks of rhythmic (e.g., with equal inter-stimulus intervals) or random (e.g., with randomly varied inter-stimulus intervals) tone sequences. Behaviorally, participants detected target sounds faster and more accurately when embedded in rhythmic streams. The fMRI response in the auditory cortex was stronger during random compared to random tone sequence processing. Simultaneously recorded N1 responses showed larger peak amplitudes and longer latencies for tones in the random (vs. the rhythmic) streams. These results reveal complementary evidence for more efficient neural and perceptual processing during temporally predictable sensory contexts. PMID:26579044

Shifts in leaf litter breakdown along a forest-pasture-urban gradient in Andean streams.

PubMed

Iñiguez-Armijos, Carlos; Rausche, Sirkka; Cueva, Augusta; Sánchez-Rodríguez, Aminael; Espinosa, Carlos; Breuer, Lutz

2016-07-01

Tropical montane ecosystems of the Andes are critically threatened by a rapid land-use change which can potentially affect stream variables, aquatic communities, and ecosystem processes such as leaf litter breakdown. However, these effects have not been sufficiently investigated in the Andean region and at high altitude locations in general. Here, we studied the influence of land use (forest-pasture-urban) on stream physico-chemical variables (e.g., water temperature, nutrient concentration, and pH), aquatic communities (macroinvertebrates and aquatic fungi) and leaf litter breakdown rates in Andean streams (southern Ecuador), and how variation in those stream physico-chemical variables affect macroinvertebrates and fungi related to leaf litter breakdown. We found that pH, water temperature, and nutrient concentration increased along the land-use gradient. Macroinvertebrate communities were significantly different between land uses. Shredder richness and abundance were lower in pasture than forest sites and totally absent in urban sites, and fungal richness and biomass were higher in forest sites than in pasture and urban sites. Leaf litter breakdown rates became slower as riparian land use changed from natural to anthropogenically disturbed conditions and were largely determined by pH, water temperature, phosphate concentration, fungal activity, and single species of leaf-shredding invertebrates. Our findings provide evidence that leaf litter breakdown in Andean streams is sensitive to riparian land-use change, with urban streams being the most affected. In addition, this study highlights the role of fungal biomass and shredder species (Phylloicus; Trichoptera and Anchytarsus; Coleoptera) on leaf litter breakdown in Andean streams and the contribution of aquatic fungi in supporting this ecosystem process when shredders are absent or present low abundance in streams affected by urbanization. Finally, we summarize important implications in terms of managing of native vegetation and riparian buffers to promote ecological integrity and functioning of tropical Andean stream ecosystems.

Multi-scale interactions affecting transport, storage, and processing of solutes and sediments in stream corridors (Invited)

NASA Astrophysics Data System (ADS)

Harvey, J. W.; Packman, A. I.

2010-12-01

Surface water and groundwater flow interact with the channel geomorphology and sediments in ways that determine how material is transported, stored, and transformed in stream corridors. Solute and sediment transport affect important ecological processes such as carbon and nutrient dynamics and stream metabolism, processes that are fundamental to stream health and function. Many individual mechanisms of transport and storage of solute and sediment have been studied, including surface water exchange between the main channel and side pools, hyporheic flow through shallow and deep subsurface flow paths, and sediment transport during both baseflow and floods. A significant challenge arises from non-linear and scale-dependent transport resulting from natural, fractal fluvial topography and associated broad, multi-scale hydrologic interactions. Connections between processes and linkages across scales are not well understood, imposing significant limitations on system predictability. The whole-stream tracer experimental approach is popular because of the spatial averaging of heterogeneous processes; however the tracer results, implemented alone and analyzed using typical models, cannot usually predict transport beyond the very specific conditions of the experiment. Furthermore, the results of whole stream tracer experiments tend to be biased due to unavoidable limitations associated with sampling frequency, measurement sensitivity, and experiment duration. We recommend that whole-stream tracer additions be augmented with hydraulic and topographic measurements and also with additional tracer measurements made directly in storage zones. We present examples of measurements that encompass interactions across spatial and temporal scales and models that are transferable to a wide range of flow and geomorphic conditions. These results show how the competitive effects between the different forces driving hyporheic flow, operating at different spatial scales, creates a situation where hyporheic fluxes cannot be accurately estimated without considering multi-scale effects. Our modeling captures the dominance of small-scale features such as bedforms that drive the majority of hyporheic flow, but it also captures how hyporheic flow is substantially modified by relatively small changes in streamflow or groundwater flow. The additional field measurements add sensitivity and power to whole stream tracer additions by improving resolution of the relative importance of storage at different scales (e.g. bar-scale versus bedform-scale). This information is critical in identifying hot spots where important biogeochemical reactions occur. In summary, interpreting multi-scale interactions in streams requires models that are physically based and that incorporate non-linear process dynamics. Such models can take advantage of increasingly comprehensive field data to integrate transport processes across spatially variable flow and geomorphic conditions. The most useful field and modeling approaches will be those that are simple enough to be easily implemented by users from various disciplines but comprehensive enough to produce meaningful predictions for a wide range of flow and geomorphic scenarios. This capability is needed to support improved strategies for protecting stream ecological health in the face of accelerating land use and climate change.

Stream Classification Tool User Manual: For Use in Applications in Hydropower-Related Evironmental Mitigation

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

McManamay, Ryan A.; Troia, Matthew J.; DeRolph, Christopher R.

Stream classifications are an inventory of different types of streams. Classifications help us explore similarities and differences among different types of streams, make inferences regarding stream ecosystem behavior, and communicate the complexities of ecosystems. We developed a nested, layered, and spatially contiguous stream classification to characterize the biophysical settings of stream reaches within the Eastern United States (~ 900,000 reaches). The classification is composed of five natural characteristics (hydrology, temperature, size, confinement, and substrate) along with several disturbance regime layers, and each was selected because of their relevance to hydropower mitigation. We developed the classification at the stream reach levelmore » using the National Hydrography Dataset Plus Version 1 (1:100k scale). The stream classification is useful to environmental mitigation for hydropower dams in multiple ways. First, it creates efficiency in the regulatory process by creating an objective and data-rich means to address meaningful mitigation actions. Secondly, the SCT addresses data gaps as it quickly provides an inventory of hydrology, temperature, morphology, and ecological communities for the immediate project area, but also surrounding streams. This includes identifying potential reference streams as those that are proximate to the hydropower facility and fall within the same class. These streams can potentially be used to identify ideal environmental conditions or identify desired ecological communities. In doing so, the stream provides some context for how streams may function, respond to dam regulation, and an overview of specific mitigation needs. Herein, we describe the methodology in developing each stream classification layer and provide a tutorial to guide applications of the classification (and associated data) in regulatory settings, such as hydropower (re)licensing.« less

TERMINAL ELECTRON ACCEPTING PROCESSES IN THE ALLUVIAL SEDIMENTS OF A HEADWATER STREAM

EPA Science Inventory

Chemical fluxes between catchments and streams are influenced by biochemical processes in the groundwater-stream water (GW-SW) ecotone, the interface between stream surface water and groundwater. Terminal electron accepting processes (TEAPs) that are utilized in respiration of ...

Effects of Fungicides on Aquatic Fungi and Bacteria

NASA Astrophysics Data System (ADS)

Conners, D. E.; Rosemond, A. D.; Black, M. C.

2005-05-01

Aquatic microorganisms play an important role in conditioning leaf litter that enters streams and serves as an important base of production for consumers. Contamination of streams by fungicides may adversely affect microorganisms and alter leaf litter processing rates. Unfortunately, microorganisms are rarely used in acute toxicity tests for fungicide evaluation and registration. We adapted the resazurin reduction assay, which is used in medical microbiology, to assess the acute toxicity of four fungicides (azoxystrobin, trifloxystrobin, kresoxim-methyl and chlorothalonil) to aquatic fungi (Articulospora tetracladia) and bacteria (Cytophaga spp.), and investigated the ability of the toxicants to inhibit leaf breakdown in microcosms. Fungi were more sensitive to fungicides than many standard test organisms (cladocerans, green algae, trout), while bacteria were often the least sensitive. All of the fungicides except kresoxim-methyl, when added to microcosms at concentrations that inhibited the fungi by 90 percent in acute tests, reduced leaf breakdown rates by an average of 14.7 percent. Thus, aquatic fungi and their associated functions in streams may be relatively sensitive to fungicides applied terrestrially that enter streams through non-point sources. These data highlight the importance of including aquatic fungi in safety assessments of pesticides for protection of microbial function.

Riparian zone hydrology and biogeochemistry as a function of stream evolution stage in glaciated landscapes of the US Northeast

NASA Astrophysics Data System (ADS)

Rook, S. P.; Vidon, P.; Walter, M. T.

2011-12-01

The management of riparian buffer strips is often regarded as one of the most economical and sustainable methods of managing non-point source pollution and water quality. However, current riparian management often follows a 'one size fits all' design, which fails to recognize the complexity of the many biogeochemical processes that regulate pollutant transformation and retention in these systems. This study addresses two critical gaps in knowledge: (1) How carbon, nitrogen, phosphorous, and iron cycles interact with one another (rather than individually). (2) How stream channel geometry and evolution regulate these nutrient cycles and greenhouse gas (GHG) dynamics in the near stream zone. This project specifically explores the hydrological and biogeochemical functioning of riparian zones across a gradient of stream meander evolution stages, with the primary goal of understanding and predicting potential interactions between nutrient dynamics in these systems. Key research questions include: (1) How does stream meander curvature affect riparian zone hydrology? (2) How does stream meander curvature influence riparian zone biogeochemistry? (3) What relationships exist among N, P, Fe, and GHG dynamics? We instrumented three riparian sites near Ithaca, NY, with a dense network of wells, piezometers, and static chambers. These sites represent three riparian zones along three evolution stages of stream meanders: an inner meander, a straight stream section, and an outer bend of the stream with an oxbow lake formation. In spring through fall 2011, water samples and gas samples were collected at a tri-weekly bases at each of the three sites. Water samples were analyzed for oxidation-reduction potential, dissolved oxygen, temperature, FeII/FeIII, nutrients (NO3-, NH4+, PO43-) and dissolved organic carbon (DOC). GHG fluxes at the soil-atmosphere interface were measured for N2O, CO2, and CH4 gases. We predict that stream curvature will significantly affect groundwater flow direction in the riparian zones. Owing to more prolonged saturation, we expect that the oxbow setting will exhibit anoxic conditions, and associated biogeochemistry. Finally, we hypothesize clear relationships among N, P, Fe, and GHG dynamics. In areas of significant denitrification, we expect to see an increase in Fe reduction, PO43- release, N2O emission, and CH4 emission, and a decrease in CO2 emission. Quantifying these interactions will enhance our ability to model riparian biogeochemical processes, promote water quality, and comprehend to what extent the promotion of riparian zones for nitrate removal is done at the expense of air quality (with respect to GHG emissions) and/or water quality (with respect to P).

Visual and visuomotor processing of hands and tools as a case study of cross talk between the dorsal and ventral streams.

PubMed

Almeida, Jorge; Amaral, Lénia; Garcea, Frank E; Aguiar de Sousa, Diana; Xu, Shan; Mahon, Bradford Z; Martins, Isabel Pavão

2018-05-24

A major principle of organization of the visual system is between a dorsal stream that processes visuomotor information and a ventral stream that supports object recognition. Most research has focused on dissociating processing across these two streams. Here we focus on how the two streams interact. We tested neurologically-intact and impaired participants in an object categorization task over two classes of objects that depend on processing within both streams-hands and tools. We measured how unconscious processing of images from one of these categories (e.g., tools) affects the recognition of images from the other category (i.e., hands). Our findings with neurologically-intact participants demonstrated that processing an image of a hand hampers the subsequent processing of an image of a tool, and vice versa. These results were not present in apraxic patients (N = 3). These findings suggest local and global inhibitory processes working in tandem to co-register information across the two streams.

Predicting nitrate discharge dynamics in mesoscale catchments using the lumped StreamGEM model and Bayesian parameter inference

NASA Astrophysics Data System (ADS)

Woodward, Simon James Roy; Wöhling, Thomas; Rode, Michael; Stenger, Roland

2017-09-01

The common practice of infrequent (e.g., monthly) stream water quality sampling for state of the environment monitoring may, when combined with high resolution stream flow data, provide sufficient information to accurately characterise the dominant nutrient transfer pathways and predict annual catchment yields. In the proposed approach, we use the spatially lumped catchment model StreamGEM to predict daily stream flow and nitrate concentration (mg L-1 NO3-N) in four contrasting mesoscale headwater catchments based on four years of daily rainfall, potential evapotranspiration, and stream flow measurements, and monthly or daily nitrate concentrations. Posterior model parameter distributions were estimated using the Markov Chain Monte Carlo sampling code DREAMZS and a log-likelihood function assuming heteroscedastic, t-distributed residuals. Despite high uncertainty in some model parameters, the flow and nitrate calibration data was well reproduced across all catchments (Nash-Sutcliffe efficiency against Log transformed data, NSL, in the range 0.62-0.83 for daily flow and 0.17-0.88 for nitrate concentration). The slight increase in the size of the residuals for a separate validation period was considered acceptable (NSL in the range 0.60-0.89 for daily flow and 0.10-0.74 for nitrate concentration, excluding one data set with limited validation data). Proportions of flow and nitrate discharge attributed to near-surface, fast seasonal groundwater and slow deeper groundwater were consistent with expectations based on catchment geology. The results for the Weida Stream in Thuringia, Germany, using monthly as opposed to daily nitrate data were, for all intents and purposes, identical, suggesting that four years of monthly nitrate sampling provides sufficient information for calibration of the StreamGEM model and prediction of catchment dynamics. This study highlights the remarkable effectiveness of process based, spatially lumped modelling with commonly available monthly stream sample data, to elucidate high resolution catchment function, when appropriate calibration methods are used that correctly handle the inherent uncertainties.

A Quantitative Assessment of the Structure and Functions of a Mature Bottomland Hardwood Community: The Iatt Creek Ecosystem Site

Treesearch

Calvin E. Meier; John A. Stanturf; Emile S. Gardiner; Paul B. Hamel; Melvin L. Warren

1999-01-01

We report our efforts, initiated in 1995, to quantify ecological processes and functions in a relatively undisturbed, mature hardwood forest. The 320-ha site is located in central Louisiana on the upper reaches of Iatt Creek, an anastomosing minor stream bottom. The forest is a mature sweetgum (Liquidambar styraciflua L.)-cherrybark oak (

Ventral and Dorsal Visual Stream Contributions to the Perception of Object Shape and Object Location

PubMed Central

Zachariou, Valentinos; Klatzky, Roberta; Behrmann, Marlene

2017-01-01

Growing evidence suggests that the functional specialization of the two cortical visual pathways may not be as distinct as originally proposed. Here, we explore possible contributions of the dorsal “where/how” visual stream to shape perception and, conversely, contributions of the ventral “what” visual stream to location perception in human adults. Participants performed a shape detection task and a location detection task while undergoing fMRI. For shape detection, comparable BOLD activation in the ventral and dorsal visual streams was observed, and the magnitude of this activation was correlated with behavioral performance. For location detection, cortical activation was significantly stronger in the dorsal than ventral visual pathway and did not correlate with the behavioral outcome. This asymmetry in cortical profile across tasks is particularly noteworthy given that the visual input was identical and that the tasks were matched for difficulty in performance. We confirmed the asymmetry in a subsequent psychophysical experiment in which participants detected changes in either object location or shape, while ignoring the other, task-irrelevant dimension. Detection of a location change was slowed by an irrelevant shape change matched for difficulty, but the reverse did not hold. We conclude that both ventral and dorsal visual streams contribute to shape perception, but that location processing appears to be essentially a function of the dorsal visual pathway. PMID:24001005

A River Runs Under It: Modeling the Distribution of Streams and Stream Burial in Large River Basins

NASA Astrophysics Data System (ADS)

Elmore, A. J.; Julian, J.; Guinn, S.; Weitzell, R.; Fitzpatrick, M.

2011-12-01

Stream network density exerts a strong control on hydrologic processes in watersheds. Over land and through soil and bedrock substrate, water moves slowly and is subject to chemical transformations unique to conditions of continuous contact with geologic materials. In contrast, once water enters stream channels it is efficiently transported out of watersheds, reducing the amount of time for biological uptake and stream nutrient processing. Therefore, stream network density dictates both the relative importance of terrestrial and aquatic influences to stream chemistry and the residence time of water in watersheds, and is critical to modeling and empirical studies aimed at understanding the impact of land use on stream water quantity and quality. Stream network density is largely a function of the number and length of the smallest streams. Methods for mapping and measuring these headwater streams range from simple measurement of stream length from existing maps, to detailed field mapping efforts, which are difficult to implement over large areas. Confounding the simplest approaches, many headwater stream reaches are not included in hydrographical maps, such as the U.S. National Hydrography Dataset (NHD), either because they were buried during the course of urban development or because they were seen as smaller than the minimum mapping size at the time of map generation. These "missing streams" severely limit the effective analyses of stream network density based on the NHD, constituting a major problem for many efforts to understand land-use impacts on streams. Here we report on research that predicts stream presence and absence by coupling field observations of headwater stream channels with maximum entropy models (MaxEnt) commonly implemented in biogeographical studies to model species distributions. The model utilizes terrain variables that are continuously accumulated along hydrologic flowpaths derived from a 10-m digital elevation model. In validation, the model correctly predicts the presence of 91% of all 10-m stream segments, and rarely miscalculates tributary numbers. We apply this model to the entire Potomac River Basin (37,800 km2) and several adjacent basins to map stream channel density and compare our results with NHD flowline data. We find that NHD underestimates stream channel density by a factor of two in most sub watersheds and this effect is strongest in the densely urbanized cities of Washington, DC and Baltimore, MD. We then apply a second predictive model based on impervious surface area data to map the extent of stream burial. Results demonstrate that the extent of stream burial increases with decreasing stream catchment area. When applied at four time steps (1975, 1990, 2001, and 2006), we find that although stream burial rates have slowed in the recent decade, streams that are not mapped in NHD flowline data continue to be buried during development. This work is the most ambitious attempt yet to map stream network density over a large region and will have lasting implications for modeling and conservation efforts.

Double dissociation of 'what' and 'where' processing in auditory cortex.

PubMed

Lomber, Stephen G; Malhotra, Shveta

2008-05-01

Studies of cortical connections or neuronal function in different cerebral areas support the hypothesis that parallel cortical processing streams, similar to those identified in visual cortex, may exist in the auditory system. However, this model has not yet been behaviorally tested. We used reversible cooling deactivation to investigate whether the individual regions in cat nonprimary auditory cortex that are responsible for processing the pattern of an acoustic stimulus or localizing a sound in space could be doubly dissociated in the same animal. We found that bilateral deactivation of the posterior auditory field resulted in deficits in a sound-localization task, whereas bilateral deactivation of the anterior auditory field resulted in deficits in a pattern-discrimination task, but not vice versa. These findings support a model of cortical organization that proposes that identifying an acoustic stimulus ('what') and its spatial location ('where') are processed in separate streams in auditory cortex.

It Systems Supporting the Management of Production Capacity

NASA Astrophysics Data System (ADS)

Milewska, Elżbieta

2017-03-01

The paper presents the problem of manufacturing process flexibility in view of a company's material and information flow stream management. The author of the article has described the functions of a production process control system and presented the characteristics of production capacity intensive and extensive reserves. The MRP II/ERP, MES and APS class IT tools supporting the process of production planning, organization and control have also been discussed.

Valve For Extracting Samples From A Process Stream

NASA Technical Reports Server (NTRS)

Callahan, Dave

1995-01-01

Valve for extracting samples from process stream includes cylindrical body bolted to pipe that contains stream. Opening in valve body matched and sealed against opening in pipe. Used to sample process streams in variety of facilities, including cement plants, plants that manufacture and reprocess plastics, oil refineries, and pipelines.

Formal development of a clock synchronization circuit

NASA Technical Reports Server (NTRS)

Miner, Paul S.

1995-01-01

This talk presents the latest stage in formal development of a fault-tolerant clock synchronization circuit. The development spans from a high level specification of the required properties to a circuit realizing the core function of the system. An abstract description of an algorithm has been verified to satisfy the high-level properties using the mechanical verification system EHDM. This abstract description is recast as a behavioral specification input to the Digital Design Derivation system (DDD) developed at Indiana University. DDD provides a formal design algebra for developing correct digital hardware. Using DDD as the principle design environment, a core circuit implementing the clock synchronization algorithm was developed. The design process consisted of standard DDD transformations augmented with an ad hoc refinement justified using the Prototype Verification System (PVS) from SRI International. Subsequent to the above development, Wilfredo Torres-Pomales discovered an area-efficient realization of the same function. Establishing correctness of this optimization requires reasoning in arithmetic, so a general verification is outside the domain of both DDD transformations and model-checking techniques. DDD represents digital hardware by systems of mutually recursive stream equations. A collection of PVS theories was developed to aid in reasoning about DDD-style streams. These theories include a combinator for defining streams that satisfy stream equations, and a means for proving stream equivalence by exhibiting a stream bisimulation. DDD was used to isolate the sub-system involved in Torres-Pomales' optimization. The equivalence between the original design and the optimized verified was verified in PVS by exhibiting a suitable bisimulation. The verification depended upon type constraints on the input streams and made extensive use of the PVS type system. The dependent types in PVS provided a useful mechanism for defining an appropriate bisimulation.

Bacterial Community Composition and Extracellular Enzyme Activity in Temperate Streambed Sediment during Drying and Rewetting

PubMed Central

Pohlon, Elisabeth; Ochoa Fandino, Adriana; Marxsen, Jürgen

2013-01-01

Droughts are among the most important disturbance events for stream ecosystems; they not only affect stream hydrology but also the stream biota. Although desiccation of streams is common in Mediterranean regions, phases of dryness in headwaters have been observed more often and for longer periods in extended temperate regions, including Central Europe, reflecting global climate change and enhanced water withdrawal. The effects of desiccation and rewetting on the bacterial community composition and extracellular enzyme activity, a key process in the carbon flow of streams and rivers, were investigated in a typical Central European stream, the Breitenbach (Hesse, Germany). Wet streambed sediment is an important habitat in streams. It was sampled and exposed in the laboratory to different drying scenarios (fast, intermediate, slow) for 13 weeks, followed by rewetting of the sediment from the fast drying scenario via a sediment core perfusion technique for 2 weeks. Bacterial community structure was analyzed using CARD-FISH and TGGE, and extracellular enzyme activity was assessed using fluorogenic model substrates. During desiccation the bacterial community composition shifted toward composition in soil, exhibiting increasing proportions of Actinobacteria and Alphaproteobacteria and decreasing proportions of Bacteroidetes and Betaproteobacteria. Simultaneously the activities of extracellular enzymes decreased, most pronounced with aminopeptidases and less pronounced with enzymes involved in the degradation of polymeric carbohydrates. After rewetting, the general ecosystem functioning, with respect to extracellular enzyme activity, recovered after 10 to 14 days. However, the bacterial community composition had not yet achieved its original composition as in unaffected sediments within this time. Thus, whether the bacterial community eventually recovers completely after these events remains unknown. Perhaps this community undergoes permanent changes, especially after harsh desiccation, followed by loss of the specialized functions of specific groups of bacteria. PMID:24386188

QUANTIFYING SPATIAL POSITION OF WETLANDS FOR STREAM HABITAT QUALITY PREDICTION

EPA Science Inventory

A watershed's capacity to store and filter water, and the resulting effects on the hydrologic regine, is a key forcing function for insteam processes and community structure. However, methods for describing wetland position have traditionally been qualitative. A Geographic Info...

Changing stream temperatures in a changing world: evaluating spatio-temporal patterns and trends across the eastern US

NASA Astrophysics Data System (ADS)

Kelleher, C.; Archfield, S. A.

2016-12-01

Stream temperatures drive biogeochemical processes and influence ecosystem health and extent, with patterns of stream temperature arising from complex interactions between climate, land cover, and in-stream diversions and dams. While each of these individual drivers may have well-understood implications for changing stream temperatures, considering the concomitant impacts of these drivers along the stream network is much more difficult. This is true especially for the eastern United States, where downstream temperature integrates many different upstream impacts. To begin to decipher the influence of these different drivers on changing stream temperatures and how these impacts may manifest through time, we examined trends for 66 sites with continuous stream temperature measurements across the eastern United States. Stream temperature records were summarized as daily mean, maximum, and mimimum values, and sites consisting of 15 or more years of data were selected for analysis. While annual stream temperatures at 53 locations were warming, a few sites on larger rivers (n = 13) have been cooling. To explore the timing of these changes as well as their implications for aquatic species, we calculated trends for seasonal extremes (average of the five warmest and coolest daily stream temperatures) during spring, summer, and fall. Interestingly, while some streams displayed strong warming trends in peak summer temperatures (n = 43), many streams also displayed cooling trends (n = 23). We also found that peak stream temperatures were warming faster in fall than in summer for many locations (n = 36). Results of this analysis show that warming (and cooling) happens at different times in different places, as a function of climate and anthropogenic impacts. Finally, we explore potential drivers of these different patterns, to determine the relative impacts of climate, land cover, and in-stream water diversions on stream temperature change. Given that the number of regulated stream miles is only increasing, improving our understanding of linkages between landscape drivers and stream temperature variation may have important outcomes for river management in a changing world.

Catchment land use-dependent effects of barrage fishponds on the functioning of headwater streams.

PubMed

Four, Brian; Arce, Evelyne; Danger, Michaël; Gaillard, Juliette; Thomas, Marielle; Banas, Damien

2017-02-01

Extensive fish production systems in continental areas are often created by damming headwater streams. However, these lentic systems favour autochthonous organic matter production. As headwater stream functioning is essentially based on allochthonous organic matter (OM) supply, the presence of barrage fishponds on headwater streams might change the main food source for benthic communities. The goal of this study was thus to identify the effects of barrage fishponds on the functioning of headwater streams. To this end, we compared leaf litter breakdown (a key ecosystem function in headwater streams), their associated invertebrate communities and fungal biomass at sites upstream and downstream of five barrage fishponds in two dominant land use systems (three in forested catchments and two in agricultural catchments). We observed significant structural and functional differences between headwater stream ecosystems in agricultural catchments and those in forested catchments. Leaf litter decay was more rapid in forest streams, with a moderate, but not significant, increase in breakdown rate downstream from the barrage fishponds. In agricultural catchments, the trend was opposite with a 2-fold lower leaf litter breakdown rate at downstream sites compared to upstream sites. Breakdown rates observed at all sites were closely correlated with fungal biomass and shredder biomass. No effect of barrage fishponds were observed in this study concerning invertebrate community structure or functional feeding groups especially in agricultural landscapes. In forest streams, we observed a decrease in organic pollution (OP)-intolerant taxa at downstream sites that was correlated with an increase in OP-tolerant taxa. These results highlighted that the influence of barrage fishponds on headwater stream functioning is complex and land use dependent. It is therefore necessary to clearly understand the various mechanisms (competition for food resources, complementarities between autochthonous and allochthonous OM) that control ecosystem functioning in different contexts in order to optimize barrage fishpond management.

A software tool to assess uncertainty in transient-storage model parameters using Monte Carlo simulations

USGS Publications Warehouse

Ward, Adam S.; Kelleher, Christa A.; Mason, Seth J. K.; Wagener, Thorsten; McIntyre, Neil; McGlynn, Brian L.; Runkel, Robert L.; Payn, Robert A.

2017-01-01

Researchers and practitioners alike often need to understand and characterize how water and solutes move through a stream in terms of the relative importance of in-stream and near-stream storage and transport processes. In-channel and subsurface storage processes are highly variable in space and time and difficult to measure. Storage estimates are commonly obtained using transient-storage models (TSMs) of the experimentally obtained solute-tracer test data. The TSM equations represent key transport and storage processes with a suite of numerical parameters. Parameter values are estimated via inverse modeling, in which parameter values are iteratively changed until model simulations closely match observed solute-tracer data. Several investigators have shown that TSM parameter estimates can be highly uncertain. When this is the case, parameter values cannot be used reliably to interpret stream-reach functioning. However, authors of most TSM studies do not evaluate or report parameter certainty. Here, we present a software tool linked to the One-dimensional Transport with Inflow and Storage (OTIS) model that enables researchers to conduct uncertainty analyses via Monte-Carlo parameter sampling and to visualize uncertainty and sensitivity results. We demonstrate application of our tool to 2 case studies and compare our results to output obtained from more traditional implementation of the OTIS model. We conclude by suggesting best practices for transient-storage modeling and recommend that future applications of TSMs include assessments of parameter certainty to support comparisons and more reliable interpretations of transport processes.

Method and apparatus for combinatorial logic signal processor in a digitally based high speed x-ray spectrometer

DOEpatents

Warburton, William K.; Zhou, Zhiquing

1999-01-01

A high speed, digitally based, signal processing system which accepts a digitized input signal and detects the presence of step-like pulses in the this data stream, extracts filtered estimates of their amplitudes, inspects for pulse pileup, and records input pulse rates and system livetime. The system has two parallel processing channels: a slow channel, which filters the data stream with a long time constant trapezoidal filter for good energy resolution; and a fast channel which filters the data stream with a short time constant trapezoidal filter, detects pulses, inspects for pileups, and captures peak values from the slow channel for good events. The presence of a simple digital interface allows the system to be easily integrated with a digital processor to produce accurate spectra at high count rates and allow all spectrometer functions to be fully automated. Because the method is digitally based, it allows pulses to be binned based on time related values, as well as on their amplitudes, if desired.

The Extrastriate Body Area Computes Desired Goal States during Action Planning123

PubMed Central

2016-01-01

Abstract How do object perception and action interact at a neural level? Here we test the hypothesis that perceptual features, processed by the ventral visuoperceptual stream, are used as priors by the dorsal visuomotor stream to specify goal-directed grasping actions. We present three main findings, which were obtained by combining time-resolved transcranial magnetic stimulation and kinematic tracking of grasp-and-rotate object manipulations, in a group of healthy human participants (N = 22). First, the extrastriate body area (EBA), in the ventral stream, provides an initial structure to motor plans, based on current and desired states of a grasped object and of the grasping hand. Second, the contributions of EBA are earlier in time than those of a caudal intraparietal region known to specify the action plan. Third, the contributions of EBA are particularly important when desired and current object configurations differ, and multiple courses of actions are possible. These findings specify the temporal and functional characteristics for a mechanism that integrates perceptual processing with motor planning. PMID:27066535

Analysis and classification of bedload transport events with variable process characteristics

NASA Astrophysics Data System (ADS)

Kreisler, Andrea; Moser, Markus; Aigner, Johann; Rindler, Rolf; Tritthart, Michael; Habersack, Helmut

2017-08-01

Knowledge about the magnitude of bedload fluxes at given hydraulic conditions in natural streams is essential for improved process understanding, for the application, calibration and validation of bedload transport formulas, and for numerical sediment transport models. Nonetheless, extensive field measurements of bedload transport are challenging and therefore data from such efforts are rare. Bedload transport has been measured comprehensively at the downstream section of the Urslau torrent in Salzburg, Austria, since 2011. We used an integrative monitoring system that combines direct (mobile basket sampler, slot sampler) and indirect measuring devices (geophone plates). Continuous information about the intensity and distribution of bedload transport within the channel cross-section is available in high spatial and temporal resolution. Seven geophone plates at a stream width of 8 m are part of a measurement system that delivers data in 1-min intervals. These geophone data are calibrated using results of direct bedload measurements, providing an opportunity to calculate bedload rates and bedload yields in selected time periods. Continuous data on the bedload transport process over three years enabled assessing several bedload transport events. The investigation of bedload transport rate/discharge relationships reveals order-of-magnitude changes. For individual events, we observed shifts in the data, reflecting different bedload rates at comparable hydraulic conditions. This study reveals that variable sediment supply conditions affect the prevailing bedload transport rates at the Urslau stream. Calculating the bedload transport efficiency enables comparing bedload transport events that exhibit similar process characteristics. Finally, we provide a conceptual model of bedload transport process types as a function of bedload transport efficiency and dimensionless stream power.

Laser homeostatics on delayed onset muscle soreness

NASA Astrophysics Data System (ADS)

Liu, T. C. Y.; Fu, D. R.; Liu, X. G.; Tian, Z. X.

2011-01-01

Delayed onset muscle soreness (DOMS) and its photobiomodulation were reviewed from the viewpoint of function-specific homeostasis (FSH) in this paper. FSH is a negative-feedback response of a biosystem to maintain the function-specific fluctuations inside the biosystem so that the function is perfectly performed. A stressor may destroy a FSH. A stress is a response of a biosystem to a stressor and may also be in stress-specific homeostasis (StSH). A low level light (LLL) is so defined that it has no effects on a function in its FSH or a stress in its StSH, but it modulate a function far from its FSH or a stress far from its StSH. For DOMS recovery, protein metabolism in the Z-line streaming muscular cell is the essential process, but the inflammation, pain and soreness are non-essential processes. For many DOMS phenomena, protein metabolism in the Z-line streaming muscular cell is in protein metabolism-specific homeostasis (PmSH) so that there are no effects of LLL although the inflammation can be inhibited and the pain can be relieved. An athlete or animal in the dysfunctional conditions such as blood flow restriction and exercise exhaustion is far from PmSH and the protein metabolism can be improved with LLL.

Differences in ecological structure, function, and native species abundance between native and invaded Hawaiian streams.

PubMed

Holitzki, Tara M; MacKenzie, Richard A; Wiegner, Tracy N; McDermid, Karla J

2013-09-01

Poeciliids, one of the most invasive species worldwide, are found on almost every continent and have been identified as an "invasive species of concern" in the United States, New Zealand, and Australia. Despite their global prevalence, few studies have quantified their impacts on tropical stream ecosystem structure, function, and biodiversity. Utilizing Hawaiian streams as model ecosystems, we documented how ecological structure, function, and native species abundance differed between poeciliid-free and poeciliid-invaded tropical streams. Stream nutrient yields, benthic biofilm biomass, densities of macroinvertebrates and fish, and community structures of benthic algae, macroinvertebrates, and fish were compared between streams with and without established poeciliid populations on the island of Hawai'i, Hawaii, USA. Sum nitrate (sigmaNO3(-) = NO3(-) + NO2(-)), total nitrogen, and total organic carbon yields were eight times, six times, and five times higher, respectively, in poeciliid streams than in poeciliid-free streams. Benthic biofilm ash-free dry mass was 1.5x higher in poeciliid streams than in poeciliid-free streams. Percentage contributions of chironomids and hydroptilid caddisflies to macroinvertebrate densities were lower in poeciliid streams compared to poeciliid-free streams, while percentage contributions of Cheumatopsyche analis caddisflies, Dugesia sp. flatworms, and oligochaetes were higher. Additionally, mean densities of native gobies were two times lower in poeciliid streams than in poeciliid-free ones, with poeciliid densities being approximately eight times higher than native fish densities. Our results, coupled with the wide distribution of invasive poeciliids across Hawaii and elsewhere in the tropics, suggest that poeciliids may negatively impact the ecosystem structure, function, and native species abundance of tropical streams they invade. This underscores the need for increased public awareness to prevent future introductions and for developing and implementing effective eradication and restoration strategies.

Hydrological Controls on Ecosystem Dynamics in Lake Fryxell, Antarctica.

PubMed

Herbei, Radu; Rytel, Alexander L; Lyons, W Berry; McKnight, Diane M; Jaros, Christopher; Gooseff, Michael N; Priscu, John C

2016-01-01

The McMurdo Dry Valleys constitute the largest ice free area of Antarctica. The area is a polar desert with an annual precipitation of ∼ 3 cm water equivalent, but contains several lakes fed by glacial melt water streams that flow from four to twelve weeks of the year. Over the past ∼20 years, data have been collected on the lakes located in Taylor Valley, Antarctica as part of the McMurdo Dry Valley Long-Term Ecological Research program (MCM-LTER). This work aims to understand the impact of climate variations on the biological processes in all the ecosystem types within Taylor Valley, including the lakes. These lakes are stratified, closed-basin systems and are perennially covered with ice. Each lake contains a variety of planktonic and benthic algae that require nutrients for photosynthesis and growth. The work presented here focuses on Lake Fryxell, one of the three main lakes of Taylor Valley; it is fed by thirteen melt-water streams. We use a functional regression approach to link the physical, chemical, and biological processes within the stream-lake system to evaluate the input of water and nutrients on the biological processes in the lakes. The technique has been shown previously to provide important insights into these Antarctic lacustrine systems where data acquisition is not temporally coherent. We use data on primary production (PPR) and chlorophyll-A (CHL)from Lake Fryxell as well as discharge observations from two streams flowing into the lake. Our findings show an association between both PPR, CHL and stream input.

Altitudinal patterns of diversity and functional traits of metabolically active microorganisms in stream biofilms

PubMed Central

Wilhelm, Linda; Besemer, Katharina; Fragner, Lena; Peter, Hannes; Weckwerth, Wolfram; Battin, Tom J

2015-01-01

Resources structure ecological communities and potentially link biodiversity to energy flow. It is commonly believed that functional traits (generalists versus specialists) involved in the exploitation of resources depend on resource availability and environmental fluctuations. The longitudinal nature of stream ecosystems provides changing resources to stream biota with yet unknown effects on microbial functional traits and community structure. We investigated the impact of autochthonous (algal extract) and allochthonous (spruce extract) resources, as they change along alpine streams from above to below the treeline, on microbial diversity, community composition and functions of benthic biofilms. Combining bromodeoxyuridine labelling and 454 pyrosequencing, we showed that diversity was lower upstream than downstream of the treeline and that community composition changed along the altitudinal gradient. We also found that, especially for allochthonous resources, specialisation by biofilm bacteria increased along that same gradient. Our results suggest that in streams below the treeline biofilm diversity, specialisation and functioning are associated with increasing niche differentiation as potentially modulated by divers allochthonous and autochthonous constituents contributing to resources. These findings expand our current understanding on biofilm structure and function in alpine streams. PMID:25978543

Global motion perception is associated with motor function in 2-year-old children.

PubMed

Thompson, Benjamin; McKinlay, Christopher J D; Chakraborty, Arijit; Anstice, Nicola S; Jacobs, Robert J; Paudel, Nabin; Yu, Tzu-Ying; Ansell, Judith M; Wouldes, Trecia A; Harding, Jane E

2017-09-29

The dorsal visual processing stream that includes V1, motion sensitive area V5 and the posterior parietal lobe, supports visually guided motor function. Two recent studies have reported associations between global motion perception, a behavioural measure of processing in V5, and motor function in pre-school and school aged children. This indicates a relationship between visual and motor development and also supports the use of global motion perception to assess overall dorsal stream function in studies of human neurodevelopment. We investigated whether associations between vision and motor function were present at 2 years of age, a substantially earlier stage of development. The Bayley III test of Infant and Toddler Development and measures of vision including visual acuity (Cardiff Acuity Cards), stereopsis (Lang stereotest) and global motion perception were attempted in 404 2-year-old children (±4 weeks). Global motion perception (quantified as a motion coherence threshold) was assessed by observing optokinetic nystagmus in response to random dot kinematograms of varying coherence. Linear regression revealed that global motion perception was modestly, but statistically significantly associated with Bayley III composite motor (r 2 =0.06, P<0.001, n=375) and gross motor scores (r 2 =0.06, p<0.001, n=375). The associations remained significant when language score was included in the regression model. In addition, when language score was included in the model, stereopsis was significantly associated with composite motor and fine motor scores, but unaided visual acuity was not statistically significantly associated with any of the motor scores. These results demonstrate that global motion perception and binocular vision are associated with motor function at an early stage of development. Global motion perception can be used as a partial measure of dorsal stream function from early childhood. Copyright © 2017 Elsevier B.V. All rights reserved.

StreamVOC - A deterministic source-apportionment model to estimate volatile organic compound concentrations in rivers and streams

USGS Publications Warehouse

Asher, William E.; Bender, David A.; Zogorski, John S.; Bartholomay, Roy C.

2006-01-01

This report documents the construction and verification of the model, StreamVOC, that estimates (1) the time- and position-dependent concentrations of volatile organic compounds (VOCs) in rivers and streams as well as (2) the source apportionment (SA) of those concentrations. The model considers how different types of sources and loss processes can act together to yield a given observed VOC concentration. Reasons for interest in the relative and absolute contributions of different sources to contaminant concentrations include the need to apportion: (1) the origins for an observed contamination, and (2) the associated human and ecosystem risks. For VOCs, sources of interest include the atmosphere (by absorption), as well as point and nonpoint inflows of VOC-containing water. Loss processes of interest include volatilization to the atmosphere, degradation, and outflows of VOC-containing water from the stream to local ground water. This report presents the details of StreamVOC and compares model output with measured concentrations for eight VOCs found in the Aberjona River at Winchester, Massachusetts. Input data for the model were obtained during a synoptic study of the stream system conducted July 11-13, 2001, as part of the National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey. The input data included a variety of basic stream characteristics (for example, flows, temperature, and VOC concentrations). The StreamVOC concentration results agreed moderately well with the measured concentration data for several VOCs and provided compound-dependent SA estimates as a function of longitudinal distance down the river. For many VOCs, the quality of the agreement between the model-simulated and measured concentrations could be improved by simple adjustments of the model input parameters. In general, this study illustrated: (1) the considerable difficulty of quantifying correctly the locations and magnitudes of ground-water-related sources of contamination in streams; and (2) that model-based estimates of stream VOC concentrations are likely to be most accurate when the major sources are point sources or tributaries where the spatial extent and magnitude of the sources are tightly constrained and easily determined.

Evaluating the Effects of Culvert Designs on Ecosystem Processes in Northern Wisconsin Streams

Treesearch

J. C. Olson; A. M. Marcarelli; A.L. Timm; S.L. Eggert; R.K. Kolka

2017-01-01

Culvert replacements are commonly undertaken to restore aquatic organism passage and stream hydrologic and geomorphic conditions, but their effects on ecosystem processes are rarely quantified. The objective of this study was to investigate the effects of two culvert replacement designs on stream ecosystem processes. The stream simulation design, where culverts...

A Function-Based Framework for Stream Assessment & Restoration Projects

EPA Pesticide Factsheets

This report lays out a framework for approaching stream assessment and restoration projects that focuses on understanding the suite of stream functions at a site in the context of what is happening in the watershed.

Quantifying hyporheic exchange at high spatial resolution using natural temperature variations along a first-order stream

NASA Astrophysics Data System (ADS)

Westhoff, M. C.; Gooseff, M. N.; Bogaard, T. A.; Savenije, H. H. G.

2011-10-01

Hyporheic exchange is an important process that underpins stream ecosystem function, and there have been numerous ways to characterize and quantify exchange flow rates and hyporheic zone size. The most common approach, using conservative stream tracer experiments and 1-D solute transport modeling, results in oversimplified representations of the system. Here we present a new approach to quantify hyporheic exchange and the size of the hyporheic zone (HZ) using high-resolution temperature measurements and a coupled 1-D transient storage and energy balance model to simulate in-stream water temperatures. Distributed temperature sensing was used to observe in-stream water temperatures with a spatial and temporal resolution of 2 and 3 min, respectively. The hyporheic exchange coefficient (which describes the rate of exchange) and the volume of the HZ were determined to range between 0 and 2.7 × 10-3 s-1 and 0 and 0.032 m3 m-1, respectively, at a spatial resolution of 1-10 m, by simulating a time series of in-stream water temperatures along a 565 m long stretch of a small first-order stream in central Luxembourg. As opposed to conventional stream tracer tests, two advantages of this approach are that exchange parameters can be determined for any stream segment over which data have been collected and that the depth of the HZ can be estimated as well. Although the presented method was tested on a small stream, it has potential for any stream where rapid (in regard to time) temperature change of a few degrees can be obtained.

Political and Economic Geomorphology: The Effect of Market Forces on Stream Restoration Designs

NASA Astrophysics Data System (ADS)

Singh, J.; Doyle, M. W.; Lave, R.; Robertson, M.

2013-12-01

Stream restoration in the U.S. is increasingly driven by compensatory mitigation; impacts to streams associated with typical land development activities must be offset via restoration of streams elsewhere. This policy application creates conditions in which restored stream ';credits' are traded under market-like conditions, comparable to wetland mitigation, carbon offsets, or endangered species habitat banking. The effect of this relatively new mechanism to finance stream restoration on design and construction is unknown. This research explores whether the introduction of a credit-based mitigation apparatus results in streams designed to maximize credit yields (i.e., ';credit-chasing') rather than focusing on restoring natural systems or functions. In other words, are market-based restored streams different from those designed for non-market purposes? We quantified geomorphic characteristics (e.g. hydraulic geometry, sinuosity, profile, bed sediment, LWD) of three types of streams: (1) a random sample of non-restored reaches, (2) streams restored for compensatory mitigation, and (3) streams restored under alternative funding sources (e.g., government grant programs, non-profit activities). We also compared the location of the types of stream reaches to determine whether there is a spatiality of restored streams. Physical data were complemented with a series of semi-structured interviews with key personnel in the stream restoration industry to solicit information on the influence of policy interpretation and market-driven factors on the design process. Preliminary analysis suggests that restoration is driving a directional shift in stream morphology in North Carolina. As a simple example, in the Piedmont, non-restored and restored channels had mean sinuosity of 1.17 and 1.23, respectively (p < 0.10). In the mountain region, non-restored and restored channels had mean sinuosity of 1.07 and 1.21, respectively (p < 0.01). In addition, restored streams were disproportionately located in very small catchments, and designs seemed to be only marginally related to the location of the stream. Provisional findings also indicate that the differences between mitigation and non-mitigation designs were less than expected. Interview data support this observation; design engineers and entrepreneurial credit providers (i.e., mitigation bankers) apparently viewed the design process as a somewhat standard, non-malleable practice. Sustaining long-term relationships with regulators, who must approve the sale of restored stream credits, was seen as critically important rather than the marginal gains to be made by manipulating particular stream designs to glean more credits. Overall, preliminary results demonstrate that regulatory frameworks, economic incentives and social relationships played a key role in driving stream restoration design in North Carolina, often homogenizing design practices and limiting ';credit chasing.'

Tracing the properties of the Sagittarius stream across the sky with LAMOST spectra

NASA Astrophysics Data System (ADS)

Walder, Madison Victoria; Carlin, Jeffrey

2018-01-01

The Sagittarius dwarf galaxy is a satellite that is currently being consumed by the Milky Way’s gravity. Its disruption has created the most prominent and widely studied tidal stream in our halo which wraps around our Galaxy with its leading arm in the northern Galactic hemisphere and its trailing arm in the southern hemisphere. Using optical spectra collected by the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) survey, we identify stars that belong to the Sagittarius tidal stream based on their positions, distances, velocities, stellar parameters, and metallicities. We trace the velocity, metallicity, and distance of the Sagittarius stream over 200 degrees of its extent on the sky using a homogenous spectroscopic data set. In doing this, we will be able to trace the stream in regions where the disk of the Galaxy makes it difficult to distinguish Sagittarius members from the far more numerous foreground stars, and therefore use the entirety of the stream to deepen our understanding of tidal disruption. We use the spectroscopic metallicities from LAMOST to derive the metallicity as a function of position along the stream, providing an important probe of the ongoing process of tidal disruption, and a window into the stellar populations that made up the Sagittarius dwarf before its cannibalization by the Milky Way.

Field guide for collecting samples for analysis of volatile organic compounds in stream water for the National Water-Quality Assessment Program

USGS Publications Warehouse

Shelton, Larry R.

1997-01-01

For many years, stream samples for analysis of volatile organic compounds have been collected without specific guidelines or a sampler designed to avoid analyte loss. In 1996, the U.S. Geological Survey's National Water-Quality Assessment Program began aggressively monitoring urban stream-water for volatile organic compounds. To assure representative samples and consistency in collection procedures, a specific sampler was designed to collect samples for analysis of volatile organic compounds in stream water. This sampler, and the collection procedures, were tested in the laboratory and in the field for compound loss, contamination, sample reproducibility, and functional capabilities. This report describes that sampler and its use, and outlines field procedures specifically designed to provide contaminant-free, reproducible volatile organic compound data from stream-water samples. These guidelines and the equipment described represent a significant change in U.S. Geological Survey instructions for collecting and processing stream-water samples for analysis of volatile organic compounds. They are intended to produce data that are both defensible and interpretable, particularly for concentrations below the microgram-per-liter level. The guidelines also contain detailed recommendations for quality-control samples.

Application of biochemical and physiological indicators for assessing recovery of fish populations in a disturbed stream.

PubMed

Adams, S Marshall; Ham, Kenneth D

2011-06-01

Recovery dynamics in a previously disturbed stream were investigated to determine the influence of a series of remedial actions on stream recovery and to evaluate the potential application of bioindicators as an environmental management tool. A suite of bioindicators, representing five different functional response groups, were measured annually for a sentinel fish species over a 15 year period during which a variety of remedial and pollution abatement actions were implemented. Trends in biochemical, physiological, condition, growth, bioenergetic, and nutritional responses demonstrated that the health status of a sentinel fish species in the disturbed stream approached that of fish in the reference stream by the end of the study. Two major remedial actions, dechlorination and water flow management, had large effects on stream recovery resulting in an improvement in the bioenergetic, disease, nutritional, and organ condition status of the sentinel fish species. A subset of bioindicators responded rather dramatically to temporal trends affecting all sites, but some indicators showed little response to disturbance or to restoration activities. In assessing recovery of aquatic systems, application of appropriate integrative structural indices along with a variety of sensitive functional bioindicators should be used to understand the mechanistic basis of stress and recovery and to reduce the risk of false positives. Understanding the mechanistic processes involved between stressors, stress responses of biota, and the recovery dynamics of aquatic systems reduces the uncertainty involved in environmental management and regulatory decisions resulting in an increased ability to predict the consequences of restoration and remedial actions for aquatic systems.

Apparatus for the liquefaction of natural gas and methods relating to same

DOEpatents

Turner, Terry D [Ammon, ID; Wilding, Bruce M [Idaho Falls, ID; McKellar, Michael G [Idaho Falls, ID

2009-09-22

An apparatus and method for producing liquefied natural gas. A liquefaction plant may be coupled to a source of unpurified natural gas, such as a natural gas pipeline at a pressure letdown station. A portion of the gas is drawn off and split into a process stream and a cooling stream. The cooling stream passes through an expander creating work output. A compressor may be driven by the work output and compresses the process stream. The compressed process stream is cooled, such as by the expanded cooling stream. The cooled, compressed process stream is expanded to liquefy the natural gas. A gas-liquid separator separates a vapor from the liquid natural gas. A portion of the liquid gas is used for additional cooling. Gas produced within the system may be recompressed for reintroduction into a receiving line or recirculation within the system for further processing.

Simulating Streamflow and Dissolved Organic Matter Export from small Forested Watersheds

NASA Astrophysics Data System (ADS)

Xu, N.; Wilson, H.; Saiers, J. E.

2010-12-01

Coupling the rainfall-runoff process and solute transport in catchment models is important for understanding the dynamics of water-quality-relevant constituents in a watershed. To simulate the hydrologic and biogeochemical processes in a parametrically parsimonious way remains challenging. The purpose of this study is to quantify the export of water and dissolved organic matter (DOM) from a forested catchment by developing and testing a coupled model for rainfall-runoff and soil-water flushing of DOM. Natural DOM plays an important role in terrestrial and aquatic systems by affecting nutrient cycling, contaminant mobility and toxicity, and drinking water quality. Stream-water discharge and DOM concentrations were measured in a first-order stream in Harvard Forest, Massachusetts. These measurements show that stream water DOM concentrations are greatest during hydrologic events induced by rainfall or snowmelt and decline to low, steady levels during periods of baseflow. Comparison of the stream-discharge data to calculations of a simple rainfall-runoff model reveals a hysteretic relationship between stream-flow rates and the storage of water within the catchment. A modified version of the rainfall-runoff model that accounts for hysteresis in the storage-discharge relationship in a parametrically simple way is capable of describing much, but not all, of the variation in the time-series data on stream discharge. Our ongoing research is aimed at linking the new rainfall-runoff formulation with coupled equations that predict soil-flushing and stream-water concentrations of DOM as functions of the temporal change in catchment water storage. This model will provide a predictive tool for examining how changes in climatic variables would affect the runoff generation and DOM fluxes from terrestrial landscape.

Catchment-Scale Sampling Reveals the Consistent Function of the Sediment-Water Interface to Remove Landscape Scale Dissolved Organic Carbon Properties

NASA Astrophysics Data System (ADS)

Lee-Cullin, J. A.; Zarnetske, J. P.; Wiewiora, E.; Ruhala, S.; Hampton, T. B.

2016-12-01

Dissolved organic carbon (DOC) is a critical component to biogeochemical cycling and water quality in surface waters. As DOC moves through stream networks, from headwaters to higher order streams, the sediment-water interface (SWI), where streams and groundwater readily interact, exerts a strong influence on DOC concentrations and compositional characteristics (i.e., molecular properties). Few studies examine SWI patterns at larger spatial scales, instead focusing primarily on site-level studies because sampling in the SWI is methodologically time and labor intensive. It is presently unknown how land use and landcover influence the fate of DOC in the SWI and therefore the function of the SWI on catchment-scale DOC conditions. Here, we performed a catchment-scale, high spatial-resolution SWI sampling campaign to test how landscape pattern DOC signatures are propagated into the stream and groundwater, and to assess the fate of these signatures when DOC travels through the SWI. We sampled across 39 sites composed of first-, second-, and third-order locations in a lowland, third-order catchment composed of diverse landscape units and properties, including wetland, upland forest, and agriculture. At each of these locations, surface water, groundwater, and SWI water were collected, including six discrete depths across the SWI. The major land use and landcover properties were also determined for each of these locations. We developed two simple generalized linear models to identify the landscape properties with greatest explanatory power for DOC conditions - one for stream water and one for groundwater. The correlation between landscape properties and surface water DOC characteristics was stronger than between landscape properties and groundwater DOC characteristics. To test if the DOC properties from surface and groundwater were preserved or removed by the SWI, the resulting best-fit models for each water source were used to predict the DOC conditions across the SWI. The models were unable to predict SWI DOC conditions, indicating that the landscape signature present in both the surface water and groundwater is removed by processes occurring in the SWI. Overall, this suggests that the SWI functions as and effective zone for processing the landscape-derived DOC signatures.

Catchment-Scale Sampling Reveals the Consistent Function of the Sediment-Water Interface to Remove Landscape Scale Dissolved Organic Carbon Properties

NASA Astrophysics Data System (ADS)

Lee-Cullin, J. A.; Zarnetske, J. P.; Wiewiora, E.; Ruhala, S.; Hampton, T. B.

2017-12-01

Dissolved organic carbon (DOC) is a critical component to biogeochemical cycling and water quality in surface waters. As DOC moves through stream networks, from headwaters to higher order streams, the sediment-water interface (SWI), where streams and groundwater readily interact, exerts a strong influence on DOC concentrations and compositional characteristics (i.e., molecular properties). Few studies examine SWI patterns at larger spatial scales, instead focusing primarily on site-level studies because sampling in the SWI is methodologically time and labor intensive. It is presently unknown how land use and landcover influence the fate of DOC in the SWI and therefore the function of the SWI on catchment-scale DOC conditions. Here, we performed a catchment-scale, high spatial-resolution SWI sampling campaign to test how landscape pattern DOC signatures are propagated into the stream and groundwater, and to assess the fate of these signatures when DOC travels through the SWI. We sampled across 39 sites composed of first-, second-, and third-order locations in a lowland, third-order catchment composed of diverse landscape units and properties, including wetland, upland forest, and agriculture. At each of these locations, surface water, groundwater, and SWI water were collected, including six discrete depths across the SWI. The major land use and landcover properties were also determined for each of these locations. We developed two simple generalized linear models to identify the landscape properties with greatest explanatory power for DOC conditions - one for stream water and one for groundwater. The correlation between landscape properties and surface water DOC characteristics was stronger than between landscape properties and groundwater DOC characteristics. To test if the DOC properties from surface and groundwater were preserved or removed by the SWI, the resulting best-fit models for each water source were used to predict the DOC conditions across the SWI. The models were unable to predict SWI DOC conditions, indicating that the landscape signature present in both the surface water and groundwater is removed by processes occurring in the SWI. Overall, this suggests that the SWI functions as and effective zone for processing the landscape-derived DOC signatures.

Catchment disturbance and stream metabolism: Patterns in ecosystem respiration and gross primary production along a gradient of upland soil and vegetation disturbance

USGS Publications Warehouse

Houser, J.N.; Mulholland, P.J.; Maloney, K.O.

2005-01-01

Catchment characteristics determine the inputs of sediments and nutrients to streams. As a result, natural or anthropogenic disturbance of upland soil and vegetation can affect instream processes. The Fort Benning Military Installation (near Columbus, Georgia) exhibits a wide range of upland disturbance levels because of spatial variability in the intensity of military training. This gradient of disturbance was used to investigate the effect of upland soil and vegetation disturbance on rates of stream metabolism (ecosystem respiration rate [ER] and gross primary production rate [GPP]). Stream metabolism was measured using an open-system, single-station approach. All streams were net heterotrophic during all seasons. ER was highest in winter and spring and lowest in summer and autumn. ER was negatively correlated with catchment disturbance level in winter, spring, and summer, but not in autumn. ER was positively correlated with abundance of coarse woody debris, but not significantly related to % benthic organic matter. GPP was low in all streams and generally not significantly correlated with disturbance level. Our results suggest that the generally intact riparian zones of these streams were not sufficient to protect them from the effect of upland disturbance, and they emphasize the role of the entire catchment in determining stream structure and function. ?? 2005 by The North American Benthological Society.

On the Validity of the Streaming Model for the Redshift-Space Correlation Function in the Linear Regime

NASA Astrophysics Data System (ADS)

Fisher, Karl B.

1995-08-01

The relation between the galaxy correlation functions in real-space and redshift-space is derived in the linear regime by an appropriate averaging of the joint probability distribution of density and velocity. The derivation recovers the familiar linear theory result on large scales but has the advantage of clearly revealing the dependence of the redshift distortions on the underlying peculiar velocity field; streaming motions give rise to distortions of θ(Ω0.6/b) while variations in the anisotropic velocity dispersion yield terms of order θ(Ω1.2/b2). This probabilistic derivation of the redshift-space correlation function is similar in spirit to the derivation of the commonly used "streaming" model, in which the distortions are given by a convolution of the real-space correlation function with a velocity distribution function. The streaming model is often used to model the redshift-space correlation function on small, highly nonlinear, scales. There have been claims in the literature, however, that the streaming model is not valid in the linear regime. Our analysis confirms this claim, but we show that the streaming model can be made consistent with linear theory provided that the model for the streaming has the functional form predicted by linear theory and that the velocity distribution is chosen to be a Gaussian with the correct linear theory dispersion.

Incorporation of water-use summaries into the StreamStats web application for Maryland

USGS Publications Warehouse

Ries, Kernell G.; Horn, Marilee A.; Nardi, Mark R.; Tessler, Steven

2010-01-01

Approximately 25,000 new households and thousands of new jobs will be established in an area that extends from southwest to northeast of Baltimore, Maryland, as a result of the Federal Base Realignment and Closure (BRAC) process, with consequent new demands on the water resources of the area. The U.S. Geological Survey, in cooperation with the Maryland Department of the Environment, has extended the area of implementation and added functionality to an existing map-based Web application named StreamStats to provide an improved tool for planning and managing the water resources in the BRAC-affected areas. StreamStats previously was implemented for only a small area surrounding Baltimore, Maryland, and it was extended to cover all BRAC-affected areas. StreamStats could provide previously published streamflow statistics, such as the 1-percent probability flood and the 7-day, 10-year low flow, for U.S. Geological Survey data-collection stations and estimates of streamflow statistics for any user-selected point on a stream within the implemented area. The application was modified for this study to also provide summaries of water withdrawals and discharges upstream from any user-selected point on a stream. This new functionality was made possible by creating a Web service that accepts a drainage-basin delineation from StreamStats, overlays it on a spatial layer of water withdrawal and discharge points, extracts the water-use data for the identified points, and sends it back to StreamStats, where it is summarized for the user. The underlying water-use data were extracted from the U.S. Geological Survey's Site-Specific Water-Use Database System (SWUDS) and placed into a Microsoft Access database that was created for this study for easy linkage to the Web service and StreamStats. This linkage of StreamStats with water-use information from SWUDS should enable Maryland regulators and planners to make more informed decisions on the use of water resources in the BRAC area, and the technology should be transferrable to other geographic areas.

Dual-stream modulation failure: a novel hypothesis for the formation and maintenance of delusions in schizophrenia.

PubMed

Speechley, William J; Ngan, Elton T C

2008-01-01

Delusions, a cardinal feature of schizophrenia, are characterized by the development and preservation of false beliefs despite reason and evidence to the contrary. A number of cognitive models have made important contributions to our understanding of delusions, though it remains unclear which core cognitive processes are malfunctioning to enable individuals with delusions to form and maintain erroneous beliefs. We propose a modified dual-stream processing model that provides a viable and testable mechanism that can account for this debilitating symptom. Dual-stream models divide decision-making into two streams: a fast, intuitive and automatic form of processing (Stream 1); and a slower, conscious and deliberative process (Stream 2). Our novel model proposes two key influences on the way these streams interact in everyday decision-making: conflict and emotion. Conflict: in most decision-making scenarios one obvious answer presents itself and the two streams converge onto the same conclusion. However, in instances where there are competing alternative possibilities, an individual often experiences dissonance, or a sense of conflict. The detection of this conflict biases processing towards the more deliberative Stream 2. Emotion: highly emotional states can result in behavior that is reflexive and action-oriented. This may be due to the power of emotionally valenced stimuli to bias reasoning towards Stream 1. We propose that in schizophrenia, an abnormal response to these two influences results in a pathological schism between Stream 1 and Stream 2, enabling erroneous intuitive explanations to coexist with contrary logical explanations of the same event. Specifically, we suggest that delusions are the result of a failure to reconcile the two streams due to both a failure of conflict to bias decision-making towards Stream 2 and an accentuated emotional bias towards Stream 1.

Using high-frequency nitrogen and carbon measurements to decouple temporal dynamics of catchment and in-stream transport and reaction processes in a headwater stream

NASA Astrophysics Data System (ADS)

Blaen, P.; Riml, J.; Khamis, K.; Krause, S.

2017-12-01

Within river catchments across the world, headwater streams represent important sites of nutrient transformation and uptake due to their high rates of microbial community processing and relative abundance in the landscape. However, separating the combined influence of in-stream transport and reaction processes from the overall catchment response can be difficult due to spatio-temporal variability in nutrient and organic matter inputs, flow regimes, and reaction rates. Recent developments in optical sensor technologies enable high-frequency, in situ nutrient measurements, and thus provide opportunities for greater insights into in-stream processes. Here, we use in-stream observations of hourly nitrate (NO3-N), dissolved organic carbon (DOC) and dissolved oxygen (DO) measurements from paired in situ sensors that bound a 1 km headwater stream reach in a mixed-use catchment in central England. We employ a spectral approach to decompose (1) variances in solute loading from the surrounding landscape, and (2) variances in reach-scale in-stream nutrient transport and reaction processes. In addition, we estimate continuous rates of reach-scale NO3-N and DOC assimilation/dissimilation, ecosystem respiration and primary production. Comparison of these results over a range of hydrological conditions (baseflow, variable storm events) and timescales (event-based, diel, seasonal) facilitates new insights into the physical and biogeochemical processes that drive in-stream nutrient dynamics in headwater streams.

Separation process using pervaporation and dephlegmation

DOEpatents

Vane, Leland M.; Mairal, Anurag P.; Ng, Alvin; Alvarez, Franklin R.; Baker, Richard W.

2004-06-29

A process for treating liquids containing organic compounds and water. The process includes a pervaporation step in conjunction with a dephlegmation step to treat at least a portion of the permeate vapor from the pervaporation step. The process yields a membrane residue stream, a stream enriched in the more volatile component (usually the organic) as the overhead stream from the dephlegmator and a condensate stream enriched in the less volatile component (usually the water) as a bottoms stream from the dephlegmator. Any of these may be the principal product of the process. The membrane separation step may also be performed in the vapor phase, or by membrane distillation.

Tool-effect: Controls on Landscape Persistence

NASA Astrophysics Data System (ADS)

Willenbring, J. K.; Brocard, G. Y.; Salles, T.; Harrison, E. J.

2017-12-01

The ability of rivers to cut through rock and to remove former land surfaces sets the pace of landscape response to mountain uplift. Because of associations between tectonism, river incision, erosion, carbon burial and silicate weathering, high rates of rock uplift are thought to initiate a cascade of processes that are linked to sequestration of CO2 over geologic timescales. However, even in some cases of landscapes experiencing rapid uplift, some portions of landscapes remain unchanged or `relict' for long periods and the fluxes of chemical weathering and physical erosion do not reflect the new tectonic regime-sometimes for millions of years following uplift. These relict portions of the landscape are often composed of subdued topography with thick soils. River incision is achieved by various processes, but one of the main contributors is bedrock abrasion by bedload. Here, we show how the presence of flat, relict landscapes in headwaters can lead to reduced incision rates and low erosion fluxes. We use a known pulse of uplift in Puerto Rico and track the river response to the uplift over time to illustrate a how landscapes in hot, humid climates can persist for millions of years even after rapid mountain uplift. We run experiments on simplified topography using numerical landscape evolution models. Typically, numerical landscape evolution models apply a standard stream power law model, whereby river incision is proportional to basal shear stress or unit stream power, and is not affected by gravel flux. We implement a formulation of the tool and cover effect model, and then we added a reinforcing effect of weathering on this process, by implementing a gravel production function. This function simulates the effect of the residence time of rocks in soil, which is expected to affect the grain-size distribution of the particles in the soil, with lower erosion rates, and longer residence time further decreasing the proportion of gravel delivered to the streams. We find that the presence of rock fragments in a landscape acts as a stream attractor and fine-grained materials retard stream incision. Thus, a relict surface with thick soils composed of sand and clays effectively protects itself from dissection.

Microbial responses to changes in flow status in temporary headwater streams: a cross-system comparison

PubMed Central

Febria, Catherine M.; Hosen, Jacob D.; Crump, Byron C.; Palmer, Margaret A.; Williams, D. Dudley

2015-01-01

Microbial communities are responsible for the bulk of biogeochemical processing in temporary headwater streams, yet there is still relatively little known about how community structure and function respond to periodic drying. Moreover, the ability to sample temporary habitats can be a logistical challenge due to the limited capability to measure and predict the timing, intensity and frequency of wet-dry events. Unsurprisingly, published datasets on microbial community structure and function are limited in scope and temporal resolution and vary widely in the molecular methods applied. We compared environmental and microbial community datasets for permanent and temporary tributaries of two different North American headwater stream systems: Speed River (Ontario, Canada) and Parkers Creek (Maryland, USA). We explored whether taxonomic diversity and community composition were altered as a result of flow permanence and compared community composition amongst streams using different 16S microbial community methods (i.e., T-RFLP and Illumina MiSeq). Contrary to our hypotheses, and irrespective of method, community composition did not respond strongly to drying. In both systems, community composition was related to site rather than drying condition. Additional network analysis on the Parkers Creek dataset indicated a shift in the central microbial relationships between temporary and permanent streams. In the permanent stream at Parkers Creek, associations of methanotrophic taxa were most dominant, whereas associations with taxa from the order Nitrospirales were more dominant in the temporary stream, particularly during dry conditions. We compared these results with existing published studies from around the world and found a wide range in community responses to drying. We conclude by proposing three hypotheses that may address contradictory results and, when tested across systems, may expand understanding of the responses of microbial communities in temporary streams to natural and human-induced fluctuations in flow-status and permanence. PMID:26089816

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

Basha, Omar M.; Keller, Murphy J.; Luebke, David R.

The Ionic Liquid (IL) [hmim][Tf 2N] was used as a physical solvent in an Aspen Plus simulation, employing the Peng-Robinson Equation of State (P-R EOS) with Boston-Mathias (BM) alpha function and standard mixing rules, to develop a conceptual process for CO 2 capture from a shifted warm fuel gas stream produced from Pittsburgh # 8 coal for a 400 MWe power plant. The physical properties of the IL, including density, viscosity, surface tension, vapor pressure and heat capacity were obtained from literature and modeled as a function of temperature. Also, available experimental solubility values for CO 2, H 2, Hmore » 2S, CO, and CH 4 in this IL were compiled and their binary interaction parameters (Δ ij and l ij) were optimized and correlated as functions of temperature. The Span-Wager Equation-of-State EOS was also employed to generate CO 2 solubilities in [hmim][Tf 2N] at high pressures (up to 10 MPa) and temperatures (up to 510 K). The conceptual process developed consisted of 4 adiabatic absorbers (2.4 m ID, 30 m high) arranged in parallel and packed with Plastic Pall Rings of 0.025 m for CO 2 capture; 3 flash drums arranged in series for solvent (IL) regeneration with the pressure-swing option; and a pressure-intercooling system for separating and pumping CO 2 up to 153 bar to the sequestration sites. The compositions of all process streams, CO 2 capture efficiency, and net power were calculated using Aspen Plus simulator. The results showed that, based on the composition of the inlet gas stream to the absorbers, 95.67 mol% of CO 2 was captured and sent to sequestration sites; 99.5 mol% of H 2 was separated and sent to turbines; the solvent exhibited a minimum loss of 0.31 mol%; and the net power balance of the entire system was 30.81 MW. These results indicated that [hmim][Tf 2N] IL could be used as a physical solvent for CO 2 capture from warm shifted fuel gas streams with high efficiency.« less

A failure of conflict to modulate dual-stream processing may underlie the formation and maintenance of delusions.

PubMed

Speechley, W J; Murray, C B; McKay, R M; Munz, M T; Ngan, E T C

2010-03-01

Dual-stream information processing proposes that reasoning is composed of two interacting processes: a fast, intuitive system (Stream 1) and a slower, more logical process (Stream 2). In non-patient controls, divergence of these streams may result in the experience of conflict, modulating decision-making towards Stream 2, and initiating a more thorough examination of the available evidence. In delusional schizophrenia patients, a failure of conflict to modulate decision-making towards Stream 2 may reduce the influence of contradictory evidence, resulting in a failure to correct erroneous beliefs. Delusional schizophrenia patients and non-patient controls completed a deductive reasoning task requiring logical validity judgments of two-part conditional statements. Half of the statements were characterized by a conflict between logical validity (Stream 2) and content believability (Stream 1). Patients were significantly worse than controls in determining the logical validity of both conflict and non-conflict conditional statements. This between groups difference was significantly greater for the conflict condition. The results are consistent with the hypothesis that delusional schizophrenia patients fail to use conflict to modulate towards Stream 2 when the two streams of reasoning arrive at incompatible judgments. This finding provides encouraging preliminary support for the Dual-Stream Modulation Failure model of delusion formation and maintenance. 2009 Elsevier Masson SAS. All rights reserved.

Cracking the Language Code: Neural Mechanisms Underlying Speech Parsing

PubMed Central

McNealy, Kristin; Mazziotta, John C.; Dapretto, Mirella

2013-01-01

Word segmentation, detecting word boundaries in continuous speech, is a critical aspect of language learning. Previous research in infants and adults demonstrated that a stream of speech can be readily segmented based solely on the statistical and speech cues afforded by the input. Using functional magnetic resonance imaging (fMRI), the neural substrate of word segmentation was examined on-line as participants listened to three streams of concatenated syllables, containing either statistical regularities alone, statistical regularities and speech cues, or no cues. Despite the participants’ inability to explicitly detect differences between the speech streams, neural activity differed significantly across conditions, with left-lateralized signal increases in temporal cortices observed only when participants listened to streams containing statistical regularities, particularly the stream containing speech cues. In a second fMRI study, designed to verify that word segmentation had implicitly taken place, participants listened to trisyllabic combinations that occurred with different frequencies in the streams of speech they just heard (“words,” 45 times; “partwords,” 15 times; “nonwords,” once). Reliably greater activity in left inferior and middle frontal gyri was observed when comparing words with partwords and, to a lesser extent, when comparing partwords with nonwords. Activity in these regions, taken to index the implicit detection of word boundaries, was positively correlated with participants’ rapid auditory processing skills. These findings provide a neural signature of on-line word segmentation in the mature brain and an initial model with which to study developmental changes in the neural architecture involved in processing speech cues during language learning. PMID:16855090

Process for recovering organic components from liquid streams

DOEpatents

Blume, Ingo; Baker, Richard W.

1991-01-01

A separation process for recovering organic components from liquid streams. The process is a combination of pervaporation and decantation. In cases where the liquid stream contains the organic to be separated in dissolved form, the pervaporation step is used to concentrate the organic to a point above the solubility limit, so that a two-phase permeate is formed and then decanted. In cases where the liquid stream is a two-phase mixture, the decantation step is performed first, to remove the organic product phase, and the residue from the decanter is then treated by pervaporation. The condensed permeate from the pervaporation unit is sufficiently concentrated in the organic component to be fed back to the decanter. The process can be tailored to produce only two streams: an essentially pure organic product stream suitable for reuse, and a residue stream for discharge or reuse.

Hydrologic response of streams restored with check dams in the Chiricahua Mountains, Arizona

USGS Publications Warehouse

Norman, Laura M.; Brinkerhoff, Fletcher C.; Gwilliam, Evan; Guertin, D. Phillip; Callegary, James B.; Goodrich, David C.; Nagler, Pamela L.; Gray, Floyd

2016-01-01

In this study, hydrological processes are evaluated to determine impacts of stream restoration in the West Turkey Creek, Chiricahua Mountains, southeast Arizona, during a summer-monsoon season (June–October of 2013). A paired-watershed approach was used to analyze the effectiveness of check dams to mitigate high flows and impact long-term maintenance of hydrologic function. One watershed had been extensively altered by the installation of numerous small check dams over the past 30 years, and the other was untreated (control). We modified and installed a new stream-gauging mechanism developed for remote areas, to compare the water balance and calculate rainfall–runoff ratios. Results show that even 30 years after installation, most of the check dams were still functional. The watershed treated with check dams has a lower runoff response to precipitation compared with the untreated, most notably in measurements of peak flow. Concerns that downstream flows would be reduced in the treated watershed, due to storage of water behind upstream check dams, were not realized; instead, flow volumes were actually higher overall in the treated stream, even though peak flows were dampened. We surmise that check dams are a useful management tool for reducing flow velocities associated with erosion and degradation and posit they can increase baseflow in aridlands.

Identifying Critical Ephemeral Streams and Reducing Impacts Associated with Utility-Scale Solar Energy Development in the Southwest United States

NASA Astrophysics Data System (ADS)

O'Connor, B. L.; Carr, A.; Patton, T.; Hamada, Y.

2011-12-01

The Bureau of Land Management (BLM) and the Department of Energy are preparing a joint programmatic environmental impact statement (PEIS) assessing the potential impacts of utility-scale solar energy development on BLM-administered lands in six southwestern states. One of the alternatives considered in the PEIS involves development within identified solar energy zones (SEZs) that individually cover approximately 10 to 1,000 km2, located primarily in desert valleys of the Basin and Range physiographic region. Land-disturbing activities in these alluvium-filled valleys have the potential to adversely affect ephemeral streams with respect to their hydrologic, geomorphic, and ecologic functions. Regulation and management of ephemeral streams typically falls under the spectrum of federal, state, and local programs, but scientifically based guidelines for protecting ephemeral streams with respect to land-development activities are largely nonexistent. The PEIS analysis attempts to identify critical ephemeral streams by evaluating the integral functions of flood conveyance, sediment transport, groundwater recharge, and supporting ecological habitats. The initial approach to classifying critical ephemeral streams involved identifying large, erosional features using available flood hazards mapping, historical peak discharges, and aerial photographs. This approach identified ephemeral features not suitable for development (based primarily on the likelihood of damaging floods and debris flows) to address flood conveyance and sediment transport functions of ephemeral streams. Groundwater recharge and the maintenance of riparian vegetation and wildlife habitats are other functions of ephemeral streams. These functions are typically associated with headwater reaches rather than large-scale erosional features. Recognizing that integral functions of ephemeral streams occur over a range of spatial scales and are driven by varying climatic-hydrologic events, the PEIS analysis assesses ephemeral streams according to their position in the basin, stream order, and the recurrence intervals of runoff events in the basin. A key constraint on this approach is the lack of high-resolution hydrologic, geomorphic, and ecological data for ephemeral streams in remote desert basins of the southwest United States. Consultation with stakeholders and management agencies is an additional component to assist with our analysis where data limitations exist. Results from these analyses identify critical ephemeral stream reaches to be avoided during development activities based on a mix of quantitative and qualitative measures. Long-term monitoring of these systems is needed to assess the avoidance criteria and to help advance development of the tools needed to help manage and protect the integral functions of ephemeral stream networks in arid environments.

Quantifying the Functionality of Ephemeral Streams at the Watershed Scale for Land Management Applications

NASA Astrophysics Data System (ADS)

O'Connor, B. L.; Hamada, Y.; Bowen, E. E.; Wuthrich, K. K.; Grippo, M. A.

2013-12-01

Land development and associated disturbances in arid environments can adversely affect the ecological functionality of ephemeral stream channels. Land use managers have limited methodologies available for assessing low-impact development plans, or for monitoring changes in stream functionality as land use changes are implemented. The development of utility-scale solar energy facilities is underway in the southwestern United States. Federal and state agencies have developed plans to concentrate facilities in specific regions to minimize transmission limitations (e.g., the Bureau of Land Management's Solar Energy Zones cover 1,100 km2). However, multiple facility footprints in a single desert valley have the potential to drastically alter the natural pattern of ephemeral stream networks. This study focuses on quantifying the sensitivity of ephemeral streams with respect to land disturbance impacts on flow and sediment conveyance, groundwater recharge, and the loss of soil and vegetative habitats. An initial assessment used publicly-available geospatial data (typically 10- to 30-m resolution) on topography, surficial geology, and soil characteristics, as well as data on historical peak discharges and aerial photographs. These datasets were used to inform a professional judgment, score-based ranking of potential land disturbance impacts on the functionality of ephemeral streams. The results were limited to mapped stream channels in the National Hydrography Dataset, but suggested that hydrological and geomorphic impacts were a greater concern in valley piedmont regions, and that habitat concerns were greater in the valley regions where vegetation is sparsely distributed. Current efforts are focused on using a remote sensing approach to obtain high-resolution information on topography, soil, and vegetation in order to map detailed ephemeral stream networks, measure channel bathymetry characteristics, and use spectral indices of soil and vegetation to develop surrogate measures of stream ecological functionality. The initial results for a small watershed (110 km2) using stereoscopic, sub-meter resolution aerial images, detected an increase of more than 100% in identified ephemeral stream channels and habitat patterns were more spatially correlated with ephemeral stream networks than was observed for the initial assessment approach. The eventual goal of these efforts is to refine the methodology for quantifying the disturbance sensitivity of ephemeral streams, from professional judgment rankings to spectral indices of stream functionality, and to close the spatial gap between the need for large-scale assessments for land management planning and the small-scale analyses and data requirements for quantifying ephemeral stream functionality.

Conflicts as Aversive Signals

ERIC Educational Resources Information Center

Dreisbach, Gesine; Fischer, Rico

2012-01-01

Theories of human action control deal with the question of how cognitive control is dynamically adjusted to task demands. The conflict monitoring theory of anterior cingulate (ACC) function suggests that the ACC monitors for response conflicts in the ongoing processing stream thereby triggering the mobilization of cognitive control. Alternatively,…

Channel processes and watershed function

Treesearch

Tom Lisle

1999-01-01

Purpose of this presentation is to put channel monitoring in context of channel processes and dispel the myth of the learned sage walking up the stream channel observing changes in the channel and extrapolating how these changes came about without looking at the rest of the watershed. The message I want to convey is it is not only O.K.to peek at the rest of the...

The Infrared Astronomical Satellite /IRAS/ Scientific Data Analysis System /SDAS/ sky flux subsystem

NASA Technical Reports Server (NTRS)

Stagner, J. R.; Girard, M. A.

1980-01-01

The sky flux subsystem of the Infrared Astronomical Satellite Scientific Data Analysis System is described. Its major output capabilities are (1) the all-sky lune maps (8-arcminute pixel size), (2) galactic plane maps (2-arcminute pixel size) and (3) regional maps of small areas such as extended sources greater than 1-degree in extent. The major processing functions are to (1) merge the CRDD and pointing data, (2) phase the detector streams, (3) compress the detector streams in the in-scan and cross-scan directions, and (4) extract data. Functional diagrams of the various capabilities of the subsystem are given. Although this device is inherently nonimaging, various calibrated and geometrically controlled imaging products are created, suitable for quantitative and qualitative scientific interpretation.

Large wood recruitment and redistribution in headwater streams in the southern Oregon Coast Range, U.S.A

USGS Publications Warehouse

May, Christine L.; Gresswell, Robert E.

2003-01-01

Large wood recruitment and redistribution mechanisms were investigated in a 3.9 km2 basin with an old-growth Pseudotsuga menziesii (Mirb.) Franco and Tsuga heterophylla (Raf.) Sarg. forest, located in the southern Coast Range of Oregon. Stream size and topographic setting strongly influenced processes that delivered wood to the channel network. In small colluvial channels draining steep hillslopes, processes associated with slope instability dominated large wood recruitment. In the larger alluvial channel, windthrow was the dominant recruitment process from the local riparian area. Consequently, colluvial channels received wood from further upslope than the alluvial channel. Input and redistribution processes influenced piece location relative to the direction of flow and thus, affected the functional role of wood. Wood recruited directly from local hillslopes and riparian areas was typically positioned adjacent to the channel or spanned its full width, and trapped sediment and wood in transport. In contrast, wood that had been fluvially redistributed was commonly located in mid-channel positions and was associated with scouring of the streambed and banks. Debris flows were a unique mechanism for creating large accumulations of wood in small streams that lacked the capacity for abundant fluvial transport of wood, and for transporting wood that was longer than the bank-full width of the channel.

Robust media processing on programmable power-constrained systems

NASA Astrophysics Data System (ADS)

McVeigh, Jeff

2005-03-01

To achieve consumer-level quality, media systems must process continuous streams of audio and video data while maintaining exacting tolerances on sampling rate, jitter, synchronization, and latency. While it is relatively straightforward to design fixed-function hardware implementations to satisfy worst-case conditions, there is a growing trend to utilize programmable multi-tasking solutions for media applications. The flexibility of these systems enables support for multiple current and future media formats, which can reduce design costs and time-to-market. This paper provides practical engineering solutions to achieve robust media processing on such systems, with specific attention given to power-constrained platforms. The techniques covered in this article utilize the fundamental concepts of algorithm and software optimization, software/hardware partitioning, stream buffering, hierarchical prioritization, and system resource and power management. A novel enhancement to dynamically adjust processor voltage and frequency based on buffer fullness to reduce system power consumption is examined in detail. The application of these techniques is provided in a case study of a portable video player implementation based on a general-purpose processor running a non real-time operating system that achieves robust playback of synchronized H.264 video and MP3 audio from local storage and streaming over 802.11.

Integrating the pulse of the riverscape and landscape: modelling stream metabolism using continuous dissolved oxygen measurements

NASA Astrophysics Data System (ADS)

Soulsby, C.; Birkel, C.; Malcolm, I.; Tetzlaff, D.

2013-12-01

Stream metabolism is a fundamental pulse of the watershed which reflects both the in-stream environment and its connectivity with the wider landscape. We used high quality, continuous (15 minute), long-term (>3 years) measurement of stream dissolved oxygen (DO) concentrations to estimate photosynthetic productivity (P) and system respiration (R) in forest and moorland reaches of an upland stream with peaty soils. We calibrated a simple five parameter numerical oxygen mass balance model driven by radiation, stream and air temperature, stream depth and re-aeration capacity. This used continuous 24-hour periods for the whole time series to identify behavioural simulations where DO simulations were re-produced sufficiently well to be considered reasonable representations of ecosystem functioning. Results were evaluated using a seasonal Regional Sensitivity Analysis and a co-linearity index for parameter sensitivity. This showed that >95 % of the behavioural models for the moorland and forest sites were identifiable and able to infer in-stream processes from the DO time series for almost half of all measured days at both sites. Days when the model failed to simulate DO levels successfully provided invaluable insight into time periods when other factors are likely to disrupt in-stream metabolic processes; these include (a) flood events when scour reduces the biomass of benthic primary producers, (b) periods of high water colour in higher summer/autumn flows and (c) low flow periods when hyporheic respiration is evident. Monthly P/R ratios <1 indicate a heterotrophic system with both sites exhibiting similar temporal patterns; with a maximum in February and a second peak during summer months. However, the estimated net ecosystem productivity (NPP) suggests that the moorland reach without riparian tree cover is likely to be a much larger source of carbon to the atmosphere (122 mmol C m-2 d-1) compared to the forested reach (64 mmol C m-2 d-1). The study indicates the value of integrating field and modelling studies of stream metabolism as a means of understanding the dynamic interactions of the riverscape and its surrounding landscape.

From one plot to many and from hillslopes to streams: Improving our understanding of catchment hydrology with a multi-scale experimental approach

NASA Astrophysics Data System (ADS)

Blume, Theresa; Weiler, Markus; Angermann, Lisa; Beiter, Daniel; Hassler, Sibylle; Kaplan, Nils; Lieder, Ernestine; Sprenger, Matthias

2017-04-01

Sustainable water resources management needs to be based on sound process understanding. This is especially true in a changing world, where boundary conditions change and models calibrated to the status quo are no longer helpful. There is a general agreement in the hydrologic community that we are in need of a better process understanding and that one of the most promising ways to achieve this is by using nested experimental designs that cover a range of scales. In the here presented study we argue that while we might be able to investigate a certain process at a plot or hillslope in detail, the real power of advancing our understanding lies in site intercomparison and if possible knowledge transfer and generalization. The experimental design of the CAOS observatory is based on sensor clusters measuring ground-, soil and stream water, sap flow and climate variables in 45 hydrological functional units which were chosen from a matrix of site characteristics (geology, land use, hillslope aspect, and topographic positions). This design allows for site intercomparisons that are based on more than one member per class and thus does not only characterize between class differences but also attempts to identify within-class variability. These distributed plot scale investigations offer a large amount of information on plot scale processes and their variability in space and time (e.g. water storage dynamics and patterns, vertical flow processes and vadose zone transit times, transpiration dynamics and patterns). However, if we want to improve our understanding of runoff generation (and thus also of nutrient and contaminant transport and export to the stream) we need to also understand how these plots link up within hillslopes and how and when these hillslopes are connected to the stream. And certainly, this is again most helpful if we do not focus on single sites but attempt experimental designs that aim at intercomparison and generalization. At the same time, the investigation of hillslope-stream connectivity is extremely challenging due to the fact that there is a high 4-dimensional variability of the involved processes and most of them are hidden from view in the subsurface. To tackle this challenge we employed a number of different field methods ranging from hillslope scale irrigation and flow-through experiments, to in depth analyses of near stream piezometer responses and stream reach tracer experiments, and then moving on to the mesoscale catchment with network wide investigations of spatial patterns of stream temperature and electric conductivity as well as of the expansion and shrinkage of the network itself. In this presentation we will provide an overview of the rationale, approach, experimental design and ongoing work, the challenges we encountered and a synthesis of exemplary results.

Methods of producing alkylated hydrocarbons from an in situ heat treatment process liquid

DOEpatents

Roes, Augustinus Wilhelmus Maria [Houston, TX; Mo, Weijian [Sugar Land, TX; Muylle, Michel Serge Marie [Houston, TX; Mandema, Remco Hugo [Houston, TX; Nair, Vijay [Katy, TX

2009-09-01

A method for producing alkylated hydrocarbons is disclosed. Formation fluid is produced from a subsurface in situ heat treatment process. The formation fluid is separated to produce a liquid stream and a first gas stream. The first gas stream includes olefins. The liquid stream is fractionated to produce at least a second gas stream including hydrocarbons having a carbon number of at least 3. The first gas stream and the second gas stream are introduced into an alkylation unit to produce alkylated hydrocarbons. At least a portion of the olefins in the first gas stream enhance alkylation.

Potential for real-time understanding of coupled hydrologic and biogeochemical processes in stream ecosystems: Future integration of telemetered data with process models for glacial meltwater streams

NASA Astrophysics Data System (ADS)

McKnight, Diane M.; Cozzetto, Karen; Cullis, James D. S.; Gooseff, Michael N.; Jaros, Christopher; Koch, Joshua C.; Lyons, W. Berry; Neupauer, Roseanna; Wlostowski, Adam

2015-08-01

While continuous monitoring of streamflow and temperature has been common for some time, there is great potential to expand continuous monitoring to include water quality parameters such as nutrients, turbidity, oxygen, and dissolved organic material. In many systems, distinguishing between watershed and stream ecosystem controls can be challenging. The usefulness of such monitoring can be enhanced by the application of quantitative models to interpret observed patterns in real time. Examples are discussed primarily from the glacial meltwater streams of the McMurdo Dry Valleys, Antarctica. Although the Dry Valley landscape is barren of plants, many streams harbor thriving cyanobacterial mats. Whereas a daily cycle of streamflow is controlled by the surface energy balance on the glaciers and the temporal pattern of solar exposure, the daily signal for biogeochemical processes controlling water quality is generated along the stream. These features result in an excellent outdoor laboratory for investigating fundamental ecosystem process and the development and validation of process-based models. As part of the McMurdo Dry Valleys Long-Term Ecological Research project, we have conducted field experiments and developed coupled biogeochemical transport models for the role of hyporheic exchange in controlling weathering reactions, microbial nitrogen cycling, and stream temperature regulation. We have adapted modeling approaches from sediment transport to understand mobilization of stream biomass with increasing flows. These models help to elucidate the role of in-stream processes in systems where watershed processes also contribute to observed patterns, and may serve as a test case for applying real-time stream ecosystem models.

Application of the Hydroecological Integrity Assessment Process for Missouri Streams

USGS Publications Warehouse

Kennen, Jonathan G.; Henriksen, James A.; Heasley, John; Cade, Brian S.; Terrell, James W.

2009-01-01

Natural flow regime concepts and theories have established the justification for maintaining or restoring the range of natural hydrologic variability so that physiochemical processes, native biodiversity, and the evolutionary potential of aquatic and riparian assemblages can be sustained. A synthesis of recent research advances in hydroecology, coupled with stream classification using hydroecologically relevant indices, has produced the Hydroecological Integrity Assessment Process (HIP). HIP consists of (1) a regional classification of streams into hydrologic stream types based on flow data from long-term gaging-station records for relatively unmodified streams, (2) an identification of stream-type specific indices that address 11 subcomponents of the flow regime, (3) an ability to establish environmental flow standards, (4) an evaluation of hydrologic alteration, and (5) a capacity to conduct alternative analyses. The process starts with the identification of a hydrologic baseline (reference condition) for selected locations, uses flow data from a stream-gage network, and proceeds to classify streams into hydrologic stream types. Concurrently, the analysis identifies a set of non-redundant and ecologically relevant hydrologic indices for 11 subcomponents of flow for each stream type. Furthermore, regional hydrologic models for synthesizing flow conditions across a region and the development of flow-ecology response relations for each stream type can be added to further enhance the process. The application of HIP to Missouri streams identified five stream types ((1) intermittent, (2) perennial runoff-flashy, (3) perennial runoff-moderate baseflow, (4) perennial groundwater-stable, and (5) perennial groundwater-super stable). Two Missouri-specific computer software programs were developed: (1) a Missouri Hydrologic Assessment Tool (MOHAT) which is used to establish a hydrologic baseline, provide options for setting environmental flow standards, and compare past and proposed hydrologic alterations; and (2) a Missouri Stream Classification Tool (MOSCT) designed for placing previously unclassified streams into one of the five pre-defined stream types.

Stream dynamics: An overview for land managers

Treesearch

Burchard H. Heede

1980-01-01

Concepts of stream dynamics are demonstrated through discussion of processes and process indicators; theory is included only where helpful to explain concepts. Present knowledge allows only qualitative prediction of stream behavior. However, such predictions show how management actions will affect the stream and its environment.

Workflow-Oriented Cyberinfrastructure for Sensor Data Analytics

NASA Astrophysics Data System (ADS)

Orcutt, J. A.; Rajasekar, A.; Moore, R. W.; Vernon, F.

2015-12-01

Sensor streams comprise an increasingly large part of Earth Science data. Analytics based on sensor data require an easy way to perform operations such as acquisition, conversion to physical units, metadata linking, sensor fusion, analysis and visualization on distributed sensor streams. Furthermore, embedding real-time sensor data into scientific workflows is of growing interest. We have implemented a scalable networked architecture that can be used to dynamically access packets of data in a stream from multiple sensors, and perform synthesis and analysis across a distributed network. Our system is based on the integrated Rule Oriented Data System (irods.org), which accesses sensor data from the Antelope Real Time Data System (brtt.com), and provides virtualized access to collections of data streams. We integrate real-time data streaming from different sources, collected for different purposes, on different time and spatial scales, and sensed by different methods. iRODS, noted for its policy-oriented data management, brings to sensor processing features and facilities such as single sign-on, third party access control lists ( ACLs), location transparency, logical resource naming, and server-side modeling capabilities while reducing the burden on sensor network operators. Rich integrated metadata support also makes it straightforward to discover data streams of interest and maintain data provenance. The workflow support in iRODS readily integrates sensor processing into any analytical pipeline. The system is developed as part of the NSF-funded Datanet Federation Consortium (datafed.org). APIs for selecting, opening, reaping and closing sensor streams are provided, along with other helper functions to associate metadata and convert sensor packets into NetCDF and JSON formats. Near real-time sensor data including seismic sensors, environmental sensors, LIDAR and video streams are available through this interface. A system for archiving sensor data and metadata in NetCDF format has been implemented and will be demonstrated at AGU.

Leaf litter processing in West Virginia mountain streams: effects of temperature and stream chemistry

Treesearch

Jacquelyn M. Rowe; William B. Perry; Sue A. Perry

1996-01-01

Climate change has the potential to alter detrital processing in headwater streams, which receive the majority of their nutrient input as terrestrial leaf litter. Early placement of experimental leaf packs in streams, one month prior to most abscission, was used as an experimental manipulation to increase stream temperature during leaf pack breakdown. We studied leaf...

Riparian communities associated with pacific northwest headwater streams: assemblages, processes, and uniqueness.

Treesearch

John S. Richardson; Robert J. Naiman; Frederick J. Swanson; David E. Hibbs

2005-01-01

Riparian areas of large streams provide important habitat to many species and control many instream processes - but is the same true for the margins of small streams? This review considers riparian areas alongside small streams in forested, mountainous areas of the Pacific Northwest and asks if there are fundamental ecological differences from larger streams and from...

Web services in the U.S. geological survey streamstats web application

USGS Publications Warehouse

Guthrie, J.D.; Dartiguenave, C.; Ries, Kernell G.

2009-01-01

StreamStats is a U.S. Geological Survey Web-based GIS application developed as a tool for waterresources planning and management, engineering design, and other applications. StreamStats' primary functionality allows users to obtain drainage-basin boundaries, basin characteristics, and streamflow statistics for gaged and ungaged sites. Recently, Web services have been developed that provide the capability to remote users and applications to access comprehensive GIS tools that are available in StreamStats, including delineating drainage-basin boundaries, computing basin characteristics, estimating streamflow statistics for user-selected locations, and determining point features that coincide with a National Hydrography Dataset (NHD) reach address. For the state of Kentucky, a web service also has been developed that provides users the ability to estimate daily time series of drainage-basin average values of daily precipitation and temperature. The use of web services allows the user to take full advantage of the datasets and processes behind the Stream Stats application without having to develop and maintain them. ?? 2009 IEEE.

Harmonic analyses of stream temperatures in the Upper Colorado River Basin

USGS Publications Warehouse

Steele, T.D.

1985-01-01

Harmonic analyses were made for available daily water-temperature records for 36 measurement sites on major streams in the Upper Colorado River Basin and for 14 measurement sites on streams in the Piceance structural basin. Generally (88 percent of the station years analyzed), more than 80 percent of the annual variability of temperatures of streams in the Upper Colorado River Basin was explained by the simple-harmonic function. Significant trends were determined for 6 of the 26 site records having 8 years or more record. In most cases, these trends resulted from construction and operation of upstream surface-water impoundments occurring during the period of record. Regional analysis of water-temperature characteristics at the 14 streamflow sites in the Piceance structural basin indicated similarities in water-temperature characteristics for a small range of measurement-site elevations. Evaluation of information content of the daily records indicated that less-than-daily measurement intervals should be considered, resulting in substantial savings in measurement and data-processing costs. (USGS)

The chemistry of iron, aluminum, and dissolved organic material in three acidic, metal-enriched, mountain streams, as controlled by watershed and in-stream processes

USGS Publications Warehouse

McKnight, Diane M.; Bencala, Kenneth E.

1990-01-01

Several studies were conducted in three acidic, metal-enriched, mountain streams, and the results are discussed together in this paper to provide a synthesis of watershed and in-stream processes controlling Fe, Al, and DOC (dissolved organic carbon) concentrations. One of the streams, the Snake River, is naturally acidic; the other two, Peru Creek and St. Kevin Gulch, receive acid mine drainage. Analysis of stream water chemistry data for the acidic headwaters of the Snake River shows that some trace metal solutes (Al, Mn, Zn) are correlated with major ions, indicating that watershed processes control their concentrations. Once in the stream, biogeochemical processes can control transport if they occur over time scales comparable to those for hydrologic transport. Examples of the following in-stream reactions are presented: (1) photoreduction and dissolution of hydrous iron oxides in response to an experimental decrease in stream pH, (2) precipitation of Al at three stream confluences, and (3) sorption of dissolved organic material by hydrous iron and aluminum oxides in a stream confluence. The extent of these reactions is evaluated using conservative tracers and a transport model that includes storage in the substream zone.

Apparatus for the liquefaction of a gas and methods relating to same

DOEpatents

Turner, Terry D [Idaho Falls, ID; Wilding, Bruce M [Idaho Falls, ID; McKellar, Michael G [Idaho Falls, ID

2009-12-29

Apparatuses and methods are provided for producing liquefied gas, such as liquefied natural gas. In one embodiment, a liquefaction plant may be coupled to a source of unpurified natural gas, such as a natural gas pipeline at a pressure letdown station. A portion of the gas is drawn off and split into a process stream and a cooling stream. The cooling stream may be sequentially pass through a compressor and an expander. The process stream may also pass through a compressor. The compressed process stream is cooled, such as by the expanded cooling stream. The cooled, compressed process stream is expanded to liquefy the natural gas. A gas-liquid separator separates the vapor from the liquid natural gas. A portion of the liquid gas may be used for additional cooling. Gas produced within the system may be recompressed for reintroduction into a receiving line.

Interdigitated Color- and Disparity-Selective Columns within Human Visual Cortical Areas V2 and V3

PubMed Central

Polimeni, Jonathan R.; Tootell, Roger B.H.

2016-01-01

In nonhuman primates (NHPs), secondary visual cortex (V2) is composed of repeating columnar stripes, which are evident in histological variations of cytochrome oxidase (CO) levels. Distinctive “thin” and “thick” stripes of dark CO staining reportedly respond selectively to stimulus variations in color and binocular disparity, respectively. Here, we first tested whether similar color-selective or disparity-selective stripes exist in human V2. If so, available evidence predicts that such stripes should (1) radiate “outward” from the V1–V2 border, (2) interdigitate, (3) differ from each other in both thickness and length, (4) be spaced ∼3.5–4 mm apart (center-to-center), and, perhaps, (5) have segregated functional connections. Second, we tested whether analogous segregated columns exist in a “next-higher” tier area, V3. To answer these questions, we used high-resolution fMRI (1 × 1 × 1 mm3) at high field (7 T), presenting color-selective or disparity-selective stimuli, plus extensive signal averaging across multiple scan sessions and cortical surface-based analysis. All hypotheses were confirmed. V2 stripes and V3 columns were reliably localized in all subjects. The two stripe/column types were largely interdigitated (e.g., nonoverlapping) in both V2 and V3. Color-selective stripes differed from disparity-selective stripes in both width (thickness) and length. Analysis of resting-state functional connections (eyes closed) showed a stronger correlation between functionally alike (compared with functionally unlike) stripes/columns in V2 and V3. These results revealed a fine-scale segregation of color-selective or disparity-selective streams within human areas V2 and V3. Together with prior evidence from NHPs, this suggests that two parallel processing streams extend from visual subcortical regions through V1, V2, and V3. SIGNIFICANCE STATEMENT In current textbooks and reviews, diagrams of cortical visual processing highlight two distinct neural-processing streams within the first and second cortical areas in monkeys. Two major streams consist of segregated cortical columns that are selectively activated by either color or ocular interactions. Because such cortical columns are so small, they were not revealed previously by conventional imaging techniques in humans. Here we demonstrate that such segregated columnar systems exist in humans. We find that, in humans, color versus binocular disparity columns extend one full area further, into the third visual area. Our approach can be extended to reveal and study additional types of columns in human cortex, perhaps including columns underlying more cognitive functions. PMID:26865609

Constructed Pools-and-Riffles: Application and Assessment in Illinois.

NASA Astrophysics Data System (ADS)

Day, D. M.; Dodd, H. R.; Carney, D. A.; Holtrop, A. M.; Whiles, M. R.; White, B.; Roseboom, D.; Kinney, W.; Keefer, L. L.; Beardsley, J.

2005-05-01

The diversity of Illinois' streams provides a broad range of conditions, and thus a variety of restoration techniques may be required to adequately compensate for watershed alterations. Resource management agencies and research institutions in the state have collaborated on a variety of applied research initiatives to assess the efficacy of various stream protection and restoration techniques. Constructed pool-and-riffle structures have received significant attention because they tend to address watershed processes (i.e., channel evolution model) and may benefit biotic communities and processes along with physical habitat. Constructed pools-and-riffles have been applied primarily to address geomorphic instability, yet understanding biological responses can provide further rationale for their use and design specifications. In three stream systems around the state, fish were collected pre- and post- installation of structures, using primarily electrofishing techniques (e.g., electric seine & backpack). In general, within the first five years after installation, changes in fish communities have included a shift from high-abundance, small cyprinid-dominated assemblages to low-density Centrarchidae and Catostomidae assemblages. Changes in macro invertebrates at selected sites included increases in filter feeders and sensitive taxa such as the Ephemeroptera, Plecoptera, and Trichoptera (EPT). Ongoing assessments will be critical for understanding long-term influences on stream ecosystem structure and function.

Securing Digital Audio using Complex Quadratic Map

NASA Astrophysics Data System (ADS)

Suryadi, MT; Satria Gunawan, Tjandra; Satria, Yudi

2018-03-01

In This digital era, exchanging data are common and easy to do, therefore it is vulnerable to be attacked and manipulated from unauthorized parties. One data type that is vulnerable to attack is digital audio. So, we need data securing method that is not vulnerable and fast. One of the methods that match all of those criteria is securing the data using chaos function. Chaos function that is used in this research is complex quadratic map (CQM). There are some parameter value that causing the key stream that is generated by CQM function to pass all 15 NIST test, this means that the key stream that is generated using this CQM is proven to be random. In addition, samples of encrypted digital sound when tested using goodness of fit test are proven to be uniform, so securing digital audio using this method is not vulnerable to frequency analysis attack. The key space is very huge about 8.1×l031 possible keys and the key sensitivity is very small about 10-10, therefore this method is also not vulnerable against brute-force attack. And finally, the processing speed for both encryption and decryption process on average about 450 times faster that its digital audio duration.

Revealing the dual streams of speech processing.

PubMed

Fridriksson, Julius; Yourganov, Grigori; Bonilha, Leonardo; Basilakos, Alexandra; Den Ouden, Dirk-Bart; Rorden, Christopher

2016-12-27

Several dual route models of human speech processing have been proposed suggesting a large-scale anatomical division between cortical regions that support motor-phonological aspects vs. lexical-semantic aspects of speech processing. However, to date, there is no complete agreement on what areas subserve each route or the nature of interactions across these routes that enables human speech processing. Relying on an extensive behavioral and neuroimaging assessment of a large sample of stroke survivors, we used a data-driven approach using principal components analysis of lesion-symptom mapping to identify brain regions crucial for performance on clusters of behavioral tasks without a priori separation into task types. Distinct anatomical boundaries were revealed between a dorsal frontoparietal stream and a ventral temporal-frontal stream associated with separate components. Collapsing over the tasks primarily supported by these streams, we characterize the dorsal stream as a form-to-articulation pathway and the ventral stream as a form-to-meaning pathway. This characterization of the division in the data reflects both the overlap between tasks supported by the two streams as well as the observation that there is a bias for phonological production tasks supported by the dorsal stream and lexical-semantic comprehension tasks supported by the ventral stream. As such, our findings show a division between two processing routes that underlie human speech processing and provide an empirical foundation for studying potential computational differences that distinguish between the two routes.

Bivariate functional data clustering: grouping streams based on a varying coefficient model of the stream water and air temperature relationship

Treesearch

H. Li; X. Deng; Andy Dolloff; E. P. Smith

2015-01-01

A novel clustering method for bivariate functional data is proposed to group streams based on their water–air temperature relationship. A distance measure is developed for bivariate curves by using a time-varying coefficient model and a weighting scheme. This distance is also adjusted by spatial correlation of streams via the variogram. Therefore, the proposed...

Biodiversity and ecosystem function in species-poor communities: community structure and leaf litter breakdown in a Pacific island stream

Treesearch

Jonathan P. Benstead; James G. March; Catherine M. Pringle; Katherine C. Ewel; John W. Short

2009-01-01

Pacific island stream communities are species-poor because of the effects of extreme geographic isolation on colonization rates of taxa common to continental regions. The effects of such low species richness on stream ecosystem function are not well understood. Here, we provide data on community structure and leaf litter breakdown rate in a virtually pristine stream on...

Hamming and Accumulator Codes Concatenated with MPSK or QAM

NASA Technical Reports Server (NTRS)

Divsalar, Dariush; Dolinar, Samuel

2009-01-01

In a proposed coding-and-modulation scheme, a high-rate binary data stream would be processed as follows: 1. The input bit stream would be demultiplexed into multiple bit streams. 2. The multiple bit streams would be processed simultaneously into a high-rate outer Hamming code that would comprise multiple short constituent Hamming codes a distinct constituent Hamming code for each stream. 3. The streams would be interleaved. The interleaver would have a block structure that would facilitate parallelization for high-speed decoding. 4. The interleaved streams would be further processed simultaneously into an inner two-state, rate-1 accumulator code that would comprise multiple constituent accumulator codes - a distinct accumulator code for each stream. 5. The resulting bit streams would be mapped into symbols to be transmitted by use of a higher-order modulation - for example, M-ary phase-shift keying (MPSK) or quadrature amplitude modulation (QAM). The novelty of the scheme lies in the concatenation of the multiple-constituent Hamming and accumulator codes and the corresponding parallel architectures of the encoder and decoder circuitry (see figure) needed to process the multiple bit streams simultaneously. As in the cases of other parallel-processing schemes, one advantage of this scheme is that the overall data rate could be much greater than the data rate of each encoder and decoder stream and, hence, the encoder and decoder could handle data at an overall rate beyond the capability of the individual encoder and decoder circuits.

Stream chemistry and groundwater-surface water interactions in Piedmont headwater streams (Charlotte, NC) prior to whole-watershed restoration

NASA Astrophysics Data System (ADS)

Vinson, D. S.; Allison, N.; Haydin, D.; Kiker, T.; Starnes, C.; Wickliff, E.; McMillan, S.; Clinton, S. M.

2017-12-01

While restoration is an established practice in urban streams, pre/post restoration hyporheic function and its potential role in nutrient processing is less well studied and understood. Here we report results from a pre-restoration sampling period in the 6.5 km2 headwaters of the Reedy Creek (RC) watershed, an urban forest stream in Charlotte, NC at the divide between the Catawba and Pee Dee river systems. Whole-watershed restoration of this deeply incised stream is scheduled to begin in fall 2017. To characterize the pre-restoration baseline condition, nutrients, DOC, temperature, and other biogeochemical parameters were analyzed quarterly from RC and 11 tributaries since 2014 and weekly since mid-2016. Riparian groundwater from 10 shallow wells has been analyzed quarterly since 2014. Nutrient concentrations vary among land uses. For example, median stream nitrate concentrations range from <0.1 mg/L as N in the undeveloped tributary to 2.5 mg/L as N in an agriculture-influenced tributary, and 0.2 mg/L as N at the RC outlet. As with nutrients, major ions, specific UV absorbance, and alkalinity vary among tributary watershed land uses. Riparian well and stream levels collected every 15 min since 2013 at 5 cross-sections indicate prevailing hydraulic gradients from the wells to the channel. At all 5 cross-sections, high stream flow events coincide with high groundwater levels, possibly indicating direct recharge to the aquifer by rain events, rather than large-scale recharge by the stream itself. Vertical hydraulic gradient measurements, slug tests, and radon-222 measurements were made at 25-75 cm deep sub-streambed piezometers. Radon-222 activities of piezometers (29-707 pCi/L; median=120 pCi/L, n=7) cover a larger range than either well water (170-647 pCi/L; median 268 pCi/L; n=7) or stream water (12-37 pCi/L, median 25 pCi/L; n=5), consistent with limited hyporheic mixing. Streambed hydraulic conductivity is requisite for significant exchange (e.g. low-K clay-rich saprolite to high-K sand and gravel are found in short stream reaches). Limited shallow downwelling may occur where the vertical hydraulic gradient and bed particle size are suitable. These results will be utilized to understand the pre- and post- restoration function of forested headwater systems in urban watersheds.

Optimized heat exchange in a CO2 de-sublimation process

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

Baxter, Larry; Terrien, Paul; Tessier, Pascal

The present invention is a process for removing carbon dioxide from a compressed gas stream including cooling the compressed gas in a first heat exchanger, introducing the cooled gas into a de-sublimating heat exchanger, thereby producing a first solid carbon dioxide stream and a first carbon dioxide poor gas stream, expanding the carbon dioxide poor gas stream, thereby producing a second solid carbon dioxide stream and a second carbon dioxide poor gas stream, combining the first solid carbon dioxide stream and the second solid carbon dioxide stream, thereby producing a combined solid carbon dioxide stream, and indirectly exchanging heat betweenmore » the combined solid carbon dioxide stream and the compressed gas in the first heat exchanger.« less

An algorithm to extract more accurate stream longitudinal profiles from unfilled DEMs

NASA Astrophysics Data System (ADS)

Byun, Jongmin; Seong, Yeong Bae

2015-08-01

Morphometric features observed from a stream longitudinal profile (SLP) reflect channel responses to lithological variation and changes in uplift or climate; therefore, they constitute essential indicators in the studies for the dynamics between tectonics, climate, and surface processes. The widespread availability of digital elevation models (DEMs) and their processing enable semi-automatic extraction of SLPs as well as additional stream profile parameters, thus reducing the time spent for extracting them and simultaneously allowing regional-scale studies of SLPs. However, careful consideration is required to extract SLPs directly from a DEM, because the DEM must be altered by depression filling process to ensure the continuity of flows across it. Such alteration inevitably introduces distortions to the SLP, such as stair steps, bias of elevation values, and inaccurate stream paths. This paper proposes a new algorithm, called maximum depth tracing algorithm (MDTA), to extract more accurate SLPs using depression-unfilled DEMs. The MDTA supposes that depressions in DEMs are not necessarily artifacts to be removed, and that elevation values within them are useful to represent more accurately the real landscape. To ensure the continuity of flows even across the unfilled DEM, the MDTA first determines the outlet of each depression and then reverses flow directions of the cells on the line of maximum depth within each depression, beginning from the outlet and toward the sink. It also calculates flow accumulation without disruption across the unfilled DEM. Comparative analysis with the profiles extracted by the hydrologic functions implemented in the ArcGIS™ was performed to illustrate the benefits from the MDTA. It shows that the MDTA provides more accurate stream paths on depression areas, and consequently reduces distortions of the SLPs derived from the paths, such as exaggerated elevation values and negatively biased slopes that are commonly observed in the SLPs built using the ArcGIS™. The algorithm proposed here, therefore, could aid all the studies requiring more reliable stream paths and SLPs from DEMs.

Drought and detritivores determine leaf litter decomposition in calcareous streams of the Ebro catchment (Spain).

PubMed

Monroy, Silvia; Menéndez, Margarita; Basaguren, Ana; Pérez, Javier; Elosegi, Arturo; Pozo, Jesús

2016-12-15

Drought, an important environmental factor affecting the functioning of stream ecosystems, is likely to become more prevalent in the Mediterranean region as a consequence of climate change and enhanced water demand. Drought can have profound impacts on leaf litter decomposition, a key ecosystem process in headwater streams, but there is still limited information on its effects at the regional scale. We measured leaf litter decomposition across a gradient of aridity in the Ebro River basin. We deployed coarse- and fine-mesh bags with alder and oak leaves in 11 Mediterranean calcareous streams spanning a range of over 400km, and determined changes in discharge, water quality, leaf-associated macroinvertebrates, leaf quality and decomposition rates. The study streams were subject to different degrees of drought, specific discharge (Ls -1 km -2 ) ranging from 0.62 to 9.99. One of the streams dried out during the experiment, another one reached residual flow, whereas the rest registered uninterrupted flow but with different degrees of flow variability. Decomposition rates differed among sites, being lowest in the 2 most water-stressed sites, but showed no general correlation with specific discharge. Microbial decomposition rates were not correlated with final nutrient content of litter nor to fungal biomass. Total decomposition rate of alder was positively correlated to the density and biomass of shredders; that of oak was not. Shredder density in alder bags showed a positive relationship with specific discharge during the decomposition experiment. Overall, the results point to a complex pattern of litter decomposition at the regional scale, as drought affects decomposition directly by emersion of bags and indirectly by affecting the functional composition and density of detritivores. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Microbial decomposition is highly sensitive to leaf litter emersion in a permanent temperate stream.

PubMed

Mora-Gómez, Juanita; Duarte, Sofia; Cássio, Fernanda; Pascoal, Cláudia; Romaní, Anna M

2018-04-15

Drought frequency and intensity in some temperate regions are forecasted to increase under the ongoing global change, which might expose permanent streams to intermittence and have severe repercussions on stream communities and ecosystem processes. In this study, we investigated the effect of drought duration on microbial decomposition of Populus nigra leaf litter in a temperate permanent stream (Oliveira, NW Portugal). Specifically, we measured the response of the structural (assemblage composition, bacterial and fungal biomass) and functional (leaf litter decomposition, extracellular enzyme activities (EEA), and fungal sporulation) parameters of fungal and bacterial communities on leaf litter exposed to emersion during different time periods (7, 14 and 21d). Emersion time affected microbial assemblages and litter decomposition, but the response differed among variables. Leaf decomposition rates and the activity of β-glucosidase, cellobiohydrolase and phosphatase were gradually reduced with increasing emersion time, while β-xylosidase reduction was similar when emersion last for 7 or more days, and the phenol oxidase reduction was similar at 14 and 21days of leaf emersion. Microbial biomass and fungal sporulation were reduced after 21days of emersion. The structure of microbial assemblages was affected by the duration of the emersion period. The shifts in fungal assemblages were correlated with a decreased microbial capacity to degrade lignin and hemicellulose in leaf litter exposed to emersion. Additionally, some resilience was observed in leaf litter mass loss, bacterial biomass, some enzyme activities and structure of fungal assemblages. Our study shows that drought can strongly alter structural and functional aspects of microbial decomposers. Therefore, the exposure of leaf litter to increasing emersion periods in temperate streams is expected to affect decomposer communities and overall decomposition of plant material by decelerating carbon cycling in streams. Copyright © 2017 Elsevier B.V. All rights reserved.

Beaded streams of Arctic permafrost landscapes

NASA Astrophysics Data System (ADS)

Arp, C. D.; Whitman, M. S.; Jones, B. M.; Grosse, G.; Gaglioti, B. V.; Heim, K. C.

2014-07-01

Beaded streams are widespread in permafrost regions and are considered a common thermokarst landform. However, little is known about their distribution, how and under what conditions they form, and how their intriguing morphology translates to ecosystem functions and habitat. Here we report on a Circum-Arctic inventory of beaded streams and a watershed-scale analysis in northern Alaska using remote sensing and field studies. We mapped over 400 channel networks with beaded morphology throughout the continuous permafrost zone of northern Alaska, Canada, and Russia and found the highest abundance associated with medium- to high-ice content permafrost in moderately sloping terrain. In the Fish Creek watershed, beaded streams accounted for half of the drainage density, occurring primarily as low-order channels initiating from lakes and drained lake basins. Beaded streams predictably transition to alluvial channels with increasing drainage area and decreasing channel slope, although this transition is modified by local controls on water and sediment delivery. Comparison of one beaded channel using repeat photography between 1948 and 2013 indicate relatively stable form and 14C dating of basal sediments suggest channel formation may be as early as the Pleistocene-Holocene transition. Contemporary processes, such as deep snow accumulation in stream gulches effectively insulates river ice and allows for perennial liquid water below most beaded stream pools. Because of this, mean annual temperatures in pool beds are greater than 2 °C, leading to the development of perennial thaw bulbs or taliks underlying these thermokarst features. In the summer, some pools stratify thermally, which reduces permafrost thaw and maintains coldwater habitats. Snowmelt generated peak-flows decrease rapidly by two or more orders of magnitude to summer low flows with slow reach-scale velocity distributions ranging from 0.1 to 0.01 m s-1, yet channel runs still move water rapidly between pools. This repeating spatial pattern associated with beaded stream morphology and hydrological dynamics may provide abundant and optimal foraging habitat for fish. Thus, beaded streams may create important ecosystem functions and habitat in many permafrost landscapes and their distribution and dynamics are only beginning to be recognized in Arctic research.

Structures linking physical and biological processes in headwater streams of the Maybeso watershed, Southeast Alaska

Treesearch

Mason D. Bryant; Takashi Gomi; Jack J. Piccolo

2007-01-01

We focus on headwater streams originating in the mountainous terrain of northern temperate rain forests. These streams rapidly descend from gradients greater than 20% to less than 5% in U-shaped glacial valleys. We use a set of studies on headwater streams in southeast Alaska to define headwater stream catchments, link physical and biological processes, and describe...

Estimation of stream depletion using values of capacitance

NASA Astrophysics Data System (ADS)

Baldenkov, Mikhail; Filimonova, Elena

2014-05-01

Compensation pumping is used to alleviate deficiencies in streamflow discharge during dry seasons. Short-term groundwater pumping can use aquifer storage instead of catchment-zone water until the drawdown reaches the edge of the stream. Stream-aquifer interactions are the key component of the hydrologic budgets and estimation of stream depletion has top-priority when evaluating the effectiveness of application of seasonal compensation pumping. Numerous analytical equations have been developed to assess the influence of groundwater pumping on nearby streams (C.V. Theis, R.E. Glover, C.G. Balmer, M.S. Hantush, C.T. Jenkins, B. Hunt, J. Bredehoeft, V.A. Zlotnik, E.L. Minkin, N.N. Lapshin, F.M. Bochever and other researchers). R.B. Wallace and Y. Darama obtained solution for cyclic conditions groundwater pumping. Numerical model approaches used in difficult hydrogeological conditions. It is offered to estimate stream depletion by seasonal pumping using values of capacitance (complex, dimensionless parameter of an aquifer system that defines the delayed effect on steamflow when there is groundwater pumping). Capacitance (C) is determined by the following equation: ( ) L* C = f( °---) , TS-Δt where S and T are the aquifer specific yield (or storage coefficient for a confined aquifer) and transmissivity, respectively; Δt is the pumping time inside one cycle, L* is the summarizing distance between the compensation well and stream edge; in some cases it can involve a function of the stream leakance and vertical leakance of the impermeable layer. Three typical hydraulic cases of compensation pumping were classified depending on their capacitance structure (i.e. the relationship between surface water and groundwater): (a) perfect hydraulic connection between the stream and aquifer; (b) imperfect hydraulic connection between the stream and aquifer; and (c) essentially imperfect hydraulic connection between the stream and the underlying confined aquifer. The form of capacitance was obtained for all three cases and is a function of aquifer hydraulic characteristics, pumping time and distance between the well and stream edge. The distance in the first and the second cases is the sum of the shortest distance between stream edge and the well and the stream leakance; in case; and in the third case, it is the sum of real distance, stream leakance and vertical leakance through the impermeable layer. A regression test between unit stream depletion (i.e. the ratio of stream reduction to pumping rate stream depletion and capacitance was performed, and power dependences were obtained in the form of Y = a + bC-0.5 The drained storage cannot be absolutely recovered by natural processes that cause 'residual' stream depletion (RSD) even in condition of perfect hydraulic connection between the stream and aquifer. The impact of various hydraulic characteristics and engineering factors on RSD was examined by numerical modeling. It was realized lack of correlation between capacitance and RSD, but exponential dependences between capacitance and the annual amplitudes of stream depletion (A) were obtained in the form of: A = 0.95 exp(- 0.776C ) Although this approach cannot assess stream-aquifer interactions to the same degree of accuracy as analytical equations of detail as a numerical model, it can provide forecast estimation with the level of primary available data.

Treatment of gas from an in situ conversion process

DOEpatents

Diaz, Zaida [Katy, TX; Del Paggio, Alan Anthony [Spring, TX; Nair, Vijay [Katy, TX; Roes, Augustinus Wilhelmus Maria [Houston, TX

2011-12-06

A method of producing methane is described. The method includes providing formation fluid from a subsurface in situ conversion process. The formation fluid is separated to produce a liquid stream and a first gas stream. The first gas stream includes olefins. At least the olefins in the first gas stream are contacted with a hydrogen source in the presence of one or more catalysts and steam to produce a second gas stream. The second gas stream is contacted with a hydrogen source in the presence of one or more additional catalysts to produce a third gas stream. The third gas stream includes methane.

Aqueous stream characterization from biomass fast pyrolysis and catalytic fast pyrolysis

DOE PAGES

Black, Brenna A.; Michener, William E.; Ramirez, Kelsey J.; ...

2016-09-05

Here, biomass pyrolysis offers a promising means to rapidly depolymerize lignocellulosic biomass for subsequent catalytic upgrading to renewable fuels. Substantial efforts are currently ongoing to optimize pyrolysis processes including various fast pyrolysis and catalytic fast pyrolysis schemes. In all cases, complex aqueous streams are generated containing solubilized organic compounds that are not converted to target fuels or chemicals and are often slated for wastewater treatment, in turn creating an economic burden on the biorefinery. Valorization of the species in these aqueous streams, however, offers significant potential for substantially improving the economics and sustainability of thermochemical biorefineries. To that end, heremore » we provide a thorough characterization of the aqueous streams from four pilot-scale pyrolysis processes: namely, from fast pyrolysis, fast pyrolysis with downstream fractionation, in situ catalytic fast pyrolysis, and ex situ catalytic fast pyrolysis. These configurations and processes represent characteristic pyrolysis processes undergoing intense development currently. Using a comprehensive suite of aqueous-compatible analytical techniques, we quantitatively characterize between 12 g kg -1 of organic carbon of a highly aqueous catalytic fast pyrolysis stream and up to 315 g kg -1 of organic carbon present in the fast pyrolysis aqueous streams. In all cases, the analysis ranges between 75 and 100% of mass closure. The composition and stream properties closely match the nature of pyrolysis processes, with high contents of carbohydrate-derived compounds in the fast pyrolysis aqueous phase, high acid content in nearly all streams, and mostly recalcitrant phenolics in the heavily deoxygenated ex situ catalytic fast pyrolysis stream. Overall, this work provides a detailed compositional analysis of aqueous streams from leading thermochemical processes -- analyses that are critical for subsequent development of selective valorization strategies for these waste streams.« less

Aqueous stream characterization from biomass fast pyrolysis and catalytic fast pyrolysis

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

Black, Brenna A.; Michener, William E.; Ramirez, Kelsey J.

Here, biomass pyrolysis offers a promising means to rapidly depolymerize lignocellulosic biomass for subsequent catalytic upgrading to renewable fuels. Substantial efforts are currently ongoing to optimize pyrolysis processes including various fast pyrolysis and catalytic fast pyrolysis schemes. In all cases, complex aqueous streams are generated containing solubilized organic compounds that are not converted to target fuels or chemicals and are often slated for wastewater treatment, in turn creating an economic burden on the biorefinery. Valorization of the species in these aqueous streams, however, offers significant potential for substantially improving the economics and sustainability of thermochemical biorefineries. To that end, heremore » we provide a thorough characterization of the aqueous streams from four pilot-scale pyrolysis processes: namely, from fast pyrolysis, fast pyrolysis with downstream fractionation, in situ catalytic fast pyrolysis, and ex situ catalytic fast pyrolysis. These configurations and processes represent characteristic pyrolysis processes undergoing intense development currently. Using a comprehensive suite of aqueous-compatible analytical techniques, we quantitatively characterize between 12 g kg -1 of organic carbon of a highly aqueous catalytic fast pyrolysis stream and up to 315 g kg -1 of organic carbon present in the fast pyrolysis aqueous streams. In all cases, the analysis ranges between 75 and 100% of mass closure. The composition and stream properties closely match the nature of pyrolysis processes, with high contents of carbohydrate-derived compounds in the fast pyrolysis aqueous phase, high acid content in nearly all streams, and mostly recalcitrant phenolics in the heavily deoxygenated ex situ catalytic fast pyrolysis stream. Overall, this work provides a detailed compositional analysis of aqueous streams from leading thermochemical processes -- analyses that are critical for subsequent development of selective valorization strategies for these waste streams.« less

GNU Radio Sandia Utilities v. 1.0

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

Gilbert, Jacob; Knee, Peter

This software adds a data handling module to the GNU Radio (GR) software defined radio (SDR) framework as well as some general-purpose function blocks (filters, metadata control, etc). This software is useful for processing bursty RF transmissions with GR, and serves as a base for applying SDR signal processing techniques to a whole burst of data at a time, as opposed to streaming data which GR has been primarily focused around.

Diminished Stream Nitrate Concentrations Linked to Dissolved Organic Carbon Dynamics After Leaf Fall

NASA Astrophysics Data System (ADS)

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

2004-05-01

Thermodynamic coupling of the nitrogen and carbon cycles has broad implications for controls on catchment nutrient fluxes. In the northeast US, leaf fall occurs in early October and the availability of organic carbon increases as the leaves decompose. At the Sleepers River Research Watershed in northeastern Vermont (USA), we sampled stream chemistry from seven nested catchments to determine how stream dissolved organic carbon (DOC) and nitrate vary as a function of flow conditions, land-use, and basin size in response to leaf fall. Following leaf fall, nitrate concentration patterns were quantitatively different from other times of the year. Under baseflow conditions, stream and soil water DOC concentrations were higher than normal, whereas nitrate concentrations declined sharply at the five smallest catchments and more modestly at the two largest catchments. Under high flow conditions, flushing of nitrate was observed, as is typical for stormflow response at Sleepers River. Our field data suggest that in-stream processing of nitrate is likely thermodynamically and kinetically favorable under baseflow but not at higher flow conditions when expanding variable source areas make hydrological connections between nitrate source areas and streams. We are working to evaluate this hypothesis with isotopic and other monitoring data, and to model the coupled interactions of water, DOC, and nitrate fluxes in these nested catchments.

Perceptual deficits of object identification: apperceptive agnosia.

PubMed

Milner, A David; Cavina-Pratesi, Cristiana

2018-01-01

It is argued here that apperceptive object agnosia (generally now known as visual form agnosia) is in reality not a kind of agnosia, but rather a form of "imperception" (to use the term coined by Hughlings Jackson). We further argue that its proximate cause is a bilateral loss (or functional loss) of the visual form processing systems embodied in the human lateral occipital cortex (area LO). According to the dual-system model of cortical visual processing elaborated by Milner and Goodale (2006), area LO constitutes a crucial component of the ventral stream, and indeed is essential for providing the figural qualities inherent in our normal visual perception of the world. According to this account, the functional loss of area LO would leave only spared visual areas within the occipito-parietal dorsal stream - dedicated to the control of visually-guided actions - potentially able to provide some aspects of visual shape processing in patients with apperceptive agnosia. We review the relevant evidence from such individuals, concentrating particularly on the well-researched patient D.F. We conclude that studies of this kind can provide useful pointers to an understanding of the processing characteristics of parietal-lobe visual mechanisms and their interactions with occipitotemporal perceptual systems in the guidance of action. Copyright © 2018 Elsevier B.V. All rights reserved.

A Self-Synthesis Approach to Perceptual Learning for Multisensory Fusion in Robotics

PubMed Central

Axenie, Cristian; Richter, Christoph; Conradt, Jörg

2016-01-01

Biological and technical systems operate in a rich multimodal environment. Due to the diversity of incoming sensory streams a system perceives and the variety of motor capabilities a system exhibits there is no single representation and no singular unambiguous interpretation of such a complex scene. In this work we propose a novel sensory processing architecture, inspired by the distributed macro-architecture of the mammalian cortex. The underlying computation is performed by a network of computational maps, each representing a different sensory quantity. All the different sensory streams enter the system through multiple parallel channels. The system autonomously associates and combines them into a coherent representation, given incoming observations. These processes are adaptive and involve learning. The proposed framework introduces mechanisms for self-creation and learning of the functional relations between the computational maps, encoding sensorimotor streams, directly from the data. Its intrinsic scalability, parallelisation, and automatic adaptation to unforeseen sensory perturbations make our approach a promising candidate for robust multisensory fusion in robotic systems. We demonstrate this by applying our model to a 3D motion estimation on a quadrotor. PMID:27775621

Method and apparatus for combinatorial logic signal processor in a digitally based high speed x-ray spectrometer

DOEpatents

Warburton, W.K.

1999-02-16

A high speed, digitally based, signal processing system is disclosed which accepts a digitized input signal and detects the presence of step-like pulses in the this data stream, extracts filtered estimates of their amplitudes, inspects for pulse pileup, and records input pulse rates and system lifetime. The system has two parallel processing channels: a slow channel, which filters the data stream with a long time constant trapezoidal filter for good energy resolution; and a fast channel which filters the data stream with a short time constant trapezoidal filter, detects pulses, inspects for pileups, and captures peak values from the slow channel for good events. The presence of a simple digital interface allows the system to be easily integrated with a digital processor to produce accurate spectra at high count rates and allow all spectrometer functions to be fully automated. Because the method is digitally based, it allows pulses to be binned based on time related values, as well as on their amplitudes, if desired. 31 figs.

Probing neural mechanisms underlying auditory stream segregation in humans by transcranial direct current stimulation (tDCS).

PubMed

Deike, Susann; Deliano, Matthias; Brechmann, André

2016-10-01

One hypothesis concerning the neural underpinnings of auditory streaming states that frequency tuning of tonotopically organized neurons in primary auditory fields in combination with physiological forward suppression is necessary for the separation of representations of high-frequency A and low-frequency B tones. The extent of spatial overlap between the tonotopic activations of A and B tones is thought to underlie the perceptual organization of streaming sequences into one coherent or two separate streams. The present study attempts to interfere with these mechanisms by transcranial direct current stimulation (tDCS) and to probe behavioral outcomes reflecting the perception of ABAB streaming sequences. We hypothesized that tDCS by modulating cortical excitability causes a change in the separateness of the representations of A and B tones, which leads to a change in the proportions of one-stream and two-stream percepts. To test this, 22 subjects were presented with ambiguous ABAB sequences of three different frequency separations (∆F) and had to decide on their current percept after receiving sham, anodal, or cathodal tDCS over the left auditory cortex. We could confirm our hypothesis at the most ambiguous ∆F condition of 6 semitones. For anodal compared with sham and cathodal stimulation, we found a significant decrease in the proportion of two-stream perception and an increase in the proportion of one-stream perception. The results demonstrate the feasibility of using tDCS to probe mechanisms underlying auditory streaming through the use of various behavioral measures. Moreover, this approach allows one to probe the functions of auditory regions and their interactions with other processing stages. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Modeling nutrient retention at the watershed scale: Does small stream research apply to the whole river network?

NASA Astrophysics Data System (ADS)

Aguilera, Rosana; Marcé, Rafael; Sabater, Sergi

2013-06-01

are conveyed from terrestrial and upstream sources through drainage networks. Streams and rivers contribute to regulate the material exported downstream by means of transformation, storage, and removal of nutrients. It has been recently suggested that the efficiency of process rates relative to available nutrient concentration in streams eventually declines, following an efficiency loss (EL) dynamics. However, most of these predictions are based at the reach scale in pristine streams, failing to describe the role of entire river networks. Models provide the means to study nutrient cycling from the stream network perspective via upscaling to the watershed the key mechanisms occurring at the reach scale. We applied a hybrid process-based and statistical model (SPARROW, Spatially Referenced Regression on Watershed Attributes) as a heuristic approach to describe in-stream nutrient processes in a highly impaired, high stream order watershed (the Llobregat River Basin, NE Spain). The in-stream decay specifications of the model were modified to include a partial saturation effect in uptake efficiency (expressed as a power law) and better capture biological nutrient retention in river systems under high anthropogenic stress. The stream decay coefficients were statistically significant in both nitrate and phosphate models, indicating the potential role of in-stream processing in limiting nutrient export. However, the EL concept did not reliably describe the patterns of nutrient uptake efficiency for the concentration gradient and streamflow values found in the Llobregat River basin, posing in doubt its complete applicability to explain nutrient retention processes in stream networks comprising highly impaired rivers.

Hydrogeologic controls on summer stream temperatures in the McKenzie River basin, Oregon

Treesearch

Christina Tague; Michael Farrell; Gordon Grant; Sarah Lewis; Serge Rey

2007-01-01

Stream temperature is a complex function of energy inputs including solar radiation and latent and sensible heat transfer. In streams where groundwater inputs are significant, energy input through advection can also be an important control on stream temperature. For an individual stream reach, models of stream temperature can take advantage of direct measurement or...

From Acoustic Segmentation to Language Processing: Evidence from Optical Imaging

PubMed Central

Obrig, Hellmuth; Rossi, Sonja; Telkemeyer, Silke; Wartenburger, Isabell

2010-01-01

During language acquisition in infancy and when learning a foreign language, the segmentation of the auditory stream into words and phrases is a complex process. Intuitively, learners use “anchors” to segment the acoustic speech stream into meaningful units like words and phrases. Regularities on a segmental (e.g., phonological) or suprasegmental (e.g., prosodic) level can provide such anchors. Regarding the neuronal processing of these two kinds of linguistic cues a left-hemispheric dominance for segmental and a right-hemispheric bias for suprasegmental information has been reported in adults. Though lateralization is common in a number of higher cognitive functions, its prominence in language may also be a key to understanding the rapid emergence of the language network in infants and the ease at which we master our language in adulthood. One question here is whether the hemispheric lateralization is driven by linguistic input per se or whether non-linguistic, especially acoustic factors, “guide” the lateralization process. Methodologically, functional magnetic resonance imaging provides unsurpassed anatomical detail for such an enquiry. However, instrumental noise, experimental constraints and interference with EEG assessment limit its applicability, pointedly in infants and also when investigating the link between auditory and linguistic processing. Optical methods have the potential to fill this gap. Here we review a number of recent studies using optical imaging to investigate hemispheric differences during segmentation and basic auditory feature analysis in language development. PMID:20725516

Visual search and the aging brain: discerning the effects of age-related brain volume shrinkage on alertness, feature binding, and attentional control.

PubMed

Müller-Oehring, Eva M; Schulte, Tilman; Rohlfing, Torsten; Pfefferbaum, Adolf; Sullivan, Edith V

2013-01-01

Decline in visuospatial abilities with advancing age has been attributed to a demise of bottom-up and top-down functions involving sensory processing, selective attention, and executive control. These functions may be differentially affected by age-related volume shrinkage of subcortical and cortical nodes subserving the dorsal and ventral processing streams and the corpus callosum mediating interhemispheric information exchange. Fifty-five healthy adults (25-84 years) underwent structural MRI and performed a visual search task to test perceptual and attentional demands by combining feature-conjunction searches with "gestalt" grouping and attentional cueing paradigms. Poorer conjunction, but not feature, search performance was related to older age and volume shrinkage of nodes in the dorsolateral processing stream. When displays allowed perceptual grouping through distractor homogeneity, poorer conjunction-search performance correlated with smaller ventrolateral prefrontal cortical and callosal volumes. An alerting cue attenuated age effects on conjunction search, and the alertness benefit was associated with thalamic, callosal, and temporal cortex volumes. Our results indicate that older adults can capitalize on early parallel stages of visual information processing, whereas age-related limitations arise at later serial processing stages requiring self-guided selective attention and executive control. These limitations are explained in part by age-related brain volume shrinkage and can be mitigated by external cues.

The Utility of Decomposition and Associated Microbial Parameters to Assess Changes in Stream Ecosystems due to Eutrophication

NASA Astrophysics Data System (ADS)

Gulis, V.; Ferreira, V. J.; Graca, M. A.

2005-05-01

Traditional approaches to assess stream ecosystem health rely on structural parameters, e.g. a variety of biotic indices. The goal of the Europe-wide RivFunction project is to develop methodology that uses functional parameters (e.g. plant litter decomposition) to this end. Here we report on decomposition experiments carried out in Portugal in five pairs of streams that differed in dissolved inorganic nutrients. On average, decomposition rates of alder and oak leaves were 2.8 and 1.4 times higher in high nutrient streams in coarse and fine mesh bags, respectively, than in corresponding reference streams. Breakdown rate correlated better with stream water SRP concentration rather than TIN. Fungal biomass and sporulation rates of aquatic hyphomycetes associated with decomposing leaves were stimulated by higher nutrient levels. Both fungal parameters measured at very early stages of decomposition (e.g. days 7-13) correlated well with overall decomposition rates. Eutrophication had no significant effect on shredder abundances in leaf bags but species richness was higher in disturbed streams. Decomposition is a key functional parameter in streams integrating many other variables and can be useful in assessing stream ecosystem health. We also argue that because decomposition is often controlled by fungal activity, microbial parameters can also be useful in bioassessment.

Developing management strategies for riparian areas.

Treesearch

D.E. Hibbs; S. Chan

2001-01-01

This talk outlines four principles that are critical to successful management of a riparian area. First, given problems both with defining historic conditions and with returning to them, attaining management goals based on restoration of ecological processes and functions will be far more successful. Second, the management goals for any stream reach must be placed in a...

Water quantity and quality at the urban-rural interface

Treesearch

Ge Sun; B. Graeme Lockaby

2012-01-01

Population growth and urban development dramatically alter natural watershed ecosystem structure and functions and stress water resources. We review studies on the impacts of urbanization on hydrologic and biogeochemical processes underlying stream water quantity and water quality issues, as well as water supply challenges in an urban environment. We conclude that...

Pervaporation process and use in treating waste stream from glycol dehydrator

DOEpatents

Kaschemekat, Jurgen; Baker, Richard W.

1994-01-01

Pervaporation processes and apparatus with few moving parts. Ideally, only one pump is used to provide essentially all of the motive power and driving force needed. The process is particularly useful for handling small streams with flow rates less than about 700 gpd. Specifically, the process can be used to treat waste streams from glycol dehydrator regeneration units.

Experiences with the Twitter Health Surveillance (THS) System

PubMed Central

Rodríguez-Martínez, Manuel

2018-01-01

Social media has become an important platform to gauge public opinion on topics related to our daily lives. In practice, processing these posts requires big data analytics tools since the volume of data and the speed of production overwhelm single-server solutions. Building an application to capture and analyze posts from social media can be a challenge simply because it requires combining a set of complex software tools that often times are tricky to configure, tune, and maintain. In many instances, the application ends up being an assorted collection of Java/Scala programs or Python scripts that developers cobble together to generate the data products they need. In this paper, we present the Twitter Health Surveillance (THS) application framework. THS is designed as a platform to allow end-users to monitor a stream of tweets, and process the stream with a combination of built-in functionality and their own user-defined functions. We discuss the architecture of THS, and describe its implementation atop the Apache Hadoop Ecosystem. We also present several lessons learned while developing our current prototype. PMID:29607412

Experiences with the Twitter Health Surveillance (THS) System.

PubMed

Rodríguez-Martínez, Manuel

2017-06-01

Social media has become an important platform to gauge public opinion on topics related to our daily lives. In practice, processing these posts requires big data analytics tools since the volume of data and the speed of production overwhelm single-server solutions. Building an application to capture and analyze posts from social media can be a challenge simply because it requires combining a set of complex software tools that often times are tricky to configure, tune, and maintain. In many instances, the application ends up being an assorted collection of Java/Scala programs or Python scripts that developers cobble together to generate the data products they need. In this paper, we present the Twitter Health Surveillance (THS) application framework. THS is designed as a platform to allow end-users to monitor a stream of tweets, and process the stream with a combination of built-in functionality and their own user-defined functions. We discuss the architecture of THS, and describe its implementation atop the Apache Hadoop Ecosystem. We also present several lessons learned while developing our current prototype.

Restoration of lowland streams: an introduction

USGS Publications Warehouse

Osborne, L.L.; Bayley, P.B.; Higler, L.W.G.; Statzner, B.; Triska, F.; Iverson, T. Moth

1993-01-01

1 This paper introduces the Lowland Streams Restoration Workshop that was held in Lund, Sweden in August 1991.2 Attenders at the Workshop participated in working groups which discussed and reported on the state of knowledge of stream restoration and identified critical areas of information need. Currently, most restoration efforts are emission-orientated (i.e. waste-water management), while the imitation of the geomorphology or of the riparian vegetation of a quasi-natural or natural reference channel receives less attention.3 Successful stream restoration requires a multidisciplinary approach within a holistic system framework. Monitoring the outcome of past, existing and future steam-restoration projects is required for information on the feasibility of alternative techniques and approaches.4 It was recommended that systems in pristine condition serve as a point of reference and not as a goal for most stream restoration projects. Restoration goals must be carefully defined so that everyone at every level understands the aim of the project. At the very least, all restoration programmes should consider geomorphic, hydrological, biological, aesthetic, and water quality aspects of the system.5 Restoration programmes should aim to create a system with a stable channel, or a channel in dynamic equilibrium that supports a self-sustaining and functionally diverse community assemblage; it should not concentrate on one species or group, except at the local level. Preserving the terrestrial -aquatic interface by setting aside riparian land corridors is critical to all stages of restoration. Additional information on the temporal and regional variability in important system processes and functions is needed.

The separate and combined effects of baryon physics and neutrino free streaming on large-scale structure

NASA Astrophysics Data System (ADS)

Mummery, Benjamin O.; McCarthy, Ian G.; Bird, Simeon; Schaye, Joop

2017-10-01

We use the cosmo-OWLS and bahamas suites of cosmological hydrodynamical simulations to explore the separate and combined effects of baryon physics (particularly feedback from active galactic nuclei, AGN) and free streaming of massive neutrinos on large-scale structure. We focus on five diagnostics: (I) the halo mass function, (II) halo mass density profiles, (III) the halo mass-concentration relation, (IV) the clustering of haloes and (v) the clustering of matter, and we explore the extent to which the effects of baryon physics and neutrino free streaming can be treated independently. Consistent with previous studies, we find that both AGN feedback and neutrino free streaming suppress the total matter power spectrum, although their scale and redshift dependences differ significantly. The inclusion of AGN feedback can significantly reduce the masses of groups and clusters, and increase their scale radii. These effects lead to a decrease in the amplitude of the mass-concentration relation and an increase in the halo autocorrelation function at fixed mass. Neutrinos also lower the masses of groups and clusters while having no significant effect on the shape of their density profiles (thus also affecting the mass-concentration relation and halo clustering in a qualitatively similar way to feedback). We show that, with only a small number of exceptions, the combined effects of baryon physics and neutrino free streaming on all five diagnostics can be estimated to typically better than a few per cent accuracy by treating these processes independently (I.e. by multiplying their separate effects).

Time-dependent observables in heavy ion collisions. Part II. In search of pressure isotropization in the φ 4 theory

NASA Astrophysics Data System (ADS)

Kovchegov, Yuri V.; Wu, Bin

2018-03-01

To understand the dynamics of thermalization in heavy ion collisions in the perturbative framework it is essential to first find corrections to the free-streaming classical gluon fields of the McLerran-Venugopalan model. The corrections that lead to deviations from free streaming (and that dominate at late proper time) would provide evidence for the onset of isotropization (and, possibly, thermalization) of the produced medium. To find such corrections we calculate the late-time two-point Green function and the energy-momentum tensor due to a single 2 → 2 scattering process involving two classical fields. To make the calculation tractable we employ the scalar φ 4 theory instead of QCD. We compare our exact diagrammatic results for these quantities to those in kinetic theory and find disagreement between the two. The disagreement is in the dependence on the proper time τ and, for the case of the two-point function, is also in the dependence on the space-time rapidity η: the exact diagrammatic calculation is, in fact, consistent with the free streaming scenario. Kinetic theory predicts a build-up of longitudinal pressure, which, however, is not observed in the exact calculation. We conclude that we find no evidence for the beginning of the transition from the free-streaming classical fields to the kinetic theory description of the produced matter after a single 2 → 2 rescattering.

Current and potential uses of bioactive molecules from marine processing waste.

PubMed

Suleria, Hafiz Ansar Rasul; Masci, Paul; Gobe, Glenda; Osborne, Simone

2016-03-15

Food industries produce huge amounts of processing waste that are often disposed of incurring expenses and impacting upon the environment. For these and other reasons, food processing waste streams, in particular marine processing waste streams, are gaining popularity amongst pharmaceutical, cosmetic and nutraceutical industries as sources of bioactive molecules. In the last 30 years, there has been a gradual increase in processed marine products with a concomitant increase in waste streams that include viscera, heads, skins, fins, bones, trimmings and shellfish waste. In 2010, these waste streams equated to approximately 24 million tonnes of mostly unused resources. Marine processing waste streams not only represent an abundant resource, they are also enriched with structurally diverse molecules that possess a broad panel of bioactivities including anti-oxidant, anti-coagulant, anti-thrombotic, anti-cancer and immune-stimulatory activities. Retrieval and characterisation of bioactive molecules from marine processing waste also contributes valuable information to the vast field of marine natural product discovery. This review summarises the current use of bioactive molecules from marine processing waste in different products and industries. Moreover, this review summarises new research into processing waste streams and the potential for adoption by industries in the creation of new products containing marine processing waste bioactives. © 2015 Society of Chemical Industry.

Process recognition in multi-element soil and stream-sediment geochemical data

USGS Publications Warehouse

Grunsky, E.C.; Drew, L.J.; Sutphin, D.M.

2009-01-01

Stream-sediment and soil geochemical data from the Upper and Lower Coastal Plains of South Carolina (USA) were studied to determine relationships between soils and stream sediments. From multi-element associations, characteristic compositions were determined for both media. Primary associations of elements reflect mineralogy, including heavy minerals, carbonates and clays, and the effects of groundwater. The effects of groundwater on element concentrations are more evident in soils than stream sediments. A "winnowing index" was created using ratios of Th to Al that revealed differing erosional and depositional environments. Both soils and stream sediments from the Upper and Lower Coastal Plains show derivation from similar materials and subsequent similar multi-element relationships, but have some distinct differences. In the Lower Coastal Plain, soils have high values of elements concentrated in heavy minerals (Ce, Y, Th) that grade into high values of elements concentrated into finer-grain-size, lower-density materials, primarily comprised of carbonates and feldspar minerals (Mg, Ca, Na, K, Al). These gradational trends in mineralogy and geochemistry are inferred to reflect reworking of materials during marine transgressions and regressions. Upper Coastal Plain stream-sediment geochemistry shows a higher winnowing index relative to soil geochemistry. A comparison of the 4 media (Upper Coastal Plain soils and stream sediments and Lower Coastal Plain soils and stream sediments) shows that Upper Coastal Plain stream sediments have a higher winnowing index and a higher concentration of elements contained within heavy minerals, whereas Lower Coastal Plain stream sediments show a strong correlation between elements typically contained within clays. It is not possible to calculate a functional relationship between stream sediment-soil compositions for all elements due to the complex history of weathering, deposition, reworking and re-deposition. However, depending on the spatial separation of the stream-sediment and soil samples, some elements are more highly correlated than others. Crown Copyright ?? 2009.

Chromium: A Stress-Processing Framework for Interactive Rendering on Clusters

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

Humphreys, G,; Houston, M.; Ng, Y.-R.

2002-01-11

We describe Chromium, a system for manipulating streams of graphics API commands on clusters of workstations. Chromium's stream filters can be arranged to create sort-first and sort-last parallel graphics architectures that, in many cases, support the same applications while using only commodity graphics accelerators. In addition, these stream filters can be extended programmatically, allowing the user to customize the stream transformations performed by nodes in a cluster. Because our stream processing mechanism is completely general, any cluster-parallel rendering algorithm can be either implemented on top of or embedded in Chromium. In this paper, we give examples of real-world applications thatmore » use Chromium to achieve good scalability on clusters of workstations, and describe other potential uses of this stream processing technology. By completely abstracting the underlying graphics architecture, network topology, and API command processing semantics, we allow a variety of applications to run in different environments.« less

Stream Assessment and Mitigation Protocols: A Review of Commonalities and Differences

EPA Pesticide Factsheets

Various stream assessment and stream mitigation protocols in use by federal and state agencies nationwide were compiled and evaluated to determine the degree to which they presented unique, comprehensive procedures to assess stream and riparian functions.

Mass, energy and material balances of SRF production process. Part 1: SRF produced from commercial and industrial waste.

PubMed

Nasrullah, Muhammad; Vainikka, Pasi; Hannula, Janne; Hurme, Markku; Kärki, Janne

2014-08-01

This paper presents the mass, energy and material balances of a solid recovered fuel (SRF) production process. The SRF is produced from commercial and industrial waste (C&IW) through mechanical treatment (MT). In this work various streams of material produced in SRF production process are analyzed for their proximate and ultimate analysis. Based on this analysis and composition of process streams their mass, energy and material balances are established for SRF production process. Here mass balance describes the overall mass flow of input waste material in the various output streams, whereas material balance describes the mass flow of components of input waste stream (such as paper and cardboard, wood, plastic (soft), plastic (hard), textile and rubber) in the various output streams of SRF production process. A commercial scale experimental campaign was conducted on an MT waste sorting plant to produce SRF from C&IW. All the process streams (input and output) produced in this MT plant were sampled and treated according to the CEN standard methods for SRF: EN 15442 and EN 15443. The results from the mass balance of SRF production process showed that of the total input C&IW material to MT waste sorting plant, 62% was recovered in the form of SRF, 4% as ferrous metal, 1% as non-ferrous metal and 21% was sorted out as reject material, 11.6% as fine fraction, and 0.4% as heavy fraction. The energy flow balance in various process streams of this SRF production process showed that of the total input energy content of C&IW to MT plant, 75% energy was recovered in the form of SRF, 20% belonged to the reject material stream and rest 5% belonged with the streams of fine fraction and heavy fraction. In the material balances, mass fractions of plastic (soft), plastic (hard), paper and cardboard and wood recovered in the SRF stream were 88%, 70%, 72% and 60% respectively of their input masses to MT plant. A high mass fraction of plastic (PVC), rubber material and non-combustibles (such as stone/rock and glass particles), was found in the reject material stream. Copyright © 2014 Elsevier Ltd. All rights reserved.

40 CFR 63.138 - Process wastewater provisions-performance standards for treatment processes managing Group 1...

Code of Federal Regulations, 2012 CFR

2012-07-01

... each treatment process. (b) Control options: Group 1 wastewater streams for Table 9 compounds. The... section. (c) Control options: Group 1 wastewater streams for Table 8 compounds. The owner or operator...) Residuals. For each residual removed from a Group 1 wastewater stream, the owner or operator shall control...

40 CFR 63.138 - Process wastewater provisions-performance standards for treatment processes managing Group 1...

Code of Federal Regulations, 2013 CFR

2013-07-01

... each treatment process. (b) Control options: Group 1 wastewater streams for Table 9 compounds. The... section. (c) Control options: Group 1 wastewater streams for Table 8 compounds. The owner or operator...) Residuals. For each residual removed from a Group 1 wastewater stream, the owner or operator shall control...

40 CFR 63.138 - Process wastewater provisions-performance standards for treatment processes managing Group 1...

Code of Federal Regulations, 2011 CFR

2011-07-01

... each treatment process. (b) Control options: Group 1 wastewater streams for Table 9 compounds. The... section. (c) Control options: Group 1 wastewater streams for Table 8 compounds. The owner or operator...) Residuals. For each residual removed from a Group 1 wastewater stream, the owner or operator shall control...

Operation of a sampling train for the analysis of environmental species in coal gasification gas-phase process streams

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

Pochan, M.J.; Massey, M.J.

1979-02-01

This report discusses the results of actual raw product gas sampling efforts and includes: Rationale for raw product gas sampling efforts; design and operation of the CMU gas sampling train; development and analysis of a sampling train data base; and conclusions and future application of results. The results of sampling activities at the CO/sub 2/-Acceptor and Hygas pilot plants proved that: The CMU gas sampling train is a valid instrument for characterization of environmental parameters in coal gasification gas-phase process streams; depending on the particular process configuration, the CMU gas sampling train can reduce gasifier effluent characterization activity to amore » single location in the raw product gas line; and in contrast to the slower operation of the EPA SASS Train, CMU's gas sampling train can collect representative effluent data at a rapid rate (approx. 2 points per hour) consistent with the rate of change of process variables, and thus function as a tool for process engineering-oriented analysis of environmental characteristics.« less

Development of an HL7 interface engine, based on tree structure and streaming algorithm, for large-size messages which include image data.

PubMed

Um, Ki Sung; Kwak, Yun Sik; Cho, Hune; Kim, Il Kon

2005-11-01

A basic assumption of Health Level Seven (HL7) protocol is 'No limitation of message length'. However, most existing commercial HL7 interface engines do limit message length because they use the string array method, which is run in the main memory for the HL7 message parsing process. Specifically, messages with image and multi-media data create a long string array and thus cause the computer system to raise critical and fatal problem. Consequently, HL7 messages cannot handle the image and multi-media data necessary in modern medical records. This study aims to solve this problem with the 'streaming algorithm' method. This new method for HL7 message parsing applies the character-stream object which process character by character between the main memory and hard disk device with the consequence that the processing load on main memory could be alleviated. The main functions of this new engine are generating, parsing, validating, browsing, sending, and receiving HL7 messages. Also, the engine can parse and generate XML-formatted HL7 messages. This new HL7 engine successfully exchanged HL7 messages with 10 megabyte size images and discharge summary information between two university hospitals.

Instream sand and gravel mining: Environmental issues and regulatory process in the United States

USGS Publications Warehouse

Meador, M.R.; Layher, A.O.

1998-01-01

Sand and gravel are widely used throughout the U.S. construction industry, but their extraction can significantly affect the physical, chemical, and biological characteristics of mined streams. Fisheries biologists often find themselves involved in the complex environmental and regulatory issues related to instream sand and gravel mining. This paper provides an overview of information presented in a symposium held at the 1997 midyear meeting of the Southern Division of the American Fisheries Society in San Antonio, Texas, to discuss environmental issues and regulatory procedures related to instream mining. Conclusions from the symposium suggest that complex physicochemical and biotic responses to disturbance such as channel incision and alteration of riparian vegetation ultimately determine the effects of instream mining. An understanding of geomorphic processes can provide insight into the effects of mining operations on stream function, and multidisciplinary empirical studies are needed to determine the relative effects of mining versus other natural and human-induced stream alterations. Mining regulations often result in a confusing regulatory process complicated, for example, by the role of the U.S. Army Corps of Engineers, which has undergone numerous changes and remains unclear. Dialogue among scientists, miners, and regulators can provide an important first step toward developing a plan that integrates biology and politics to protect aquatic resources.

Influences of harvesting on functions of floodplain forests associated with low-order, blackwater streams

Treesearch

B.G. Lockaby; R.H. Jones; R.G. Clawson; J.S. Meadows; John A. Stanturf; F.C. Thornton

1997-01-01

The influence of both aerial and ground-based harvesting on functions of forested floodplains of low-order streams was studied during a two-year period. The study sites were associated with low-order, blackwater streams with infertile and primarily organic soils. Responses to harvesting were assessed in relation to water quality, denitrification, hydrology,...

Assessment of corn and banana leaves as potential standardized substrates for leaf decomposition in streams affected by mountaintop removal coal mining, West Virginia, USA

EPA Science Inventory

Mountaintop removal and valley filling is a method of coal mining that buries Central Appalachian headwater streams. A 2007 federal court ruling highlighted the need for measurement of both ecosystem structure and function when assessing streams for mitigaton. Rapid functional as...

Complex Catchment Processes that Control Stream Nitrogen and Organic Matter Concentrations in a Northeastern USA Upland Catchment

NASA Astrophysics Data System (ADS)

Sebestyen, S. D.; Shanley, J. B.; Pellerin, B.; Saraceno, J.; Aiken, G. R.; Boyer, E. W.; Doctor, D. H.; Kendall, C.

2009-05-01

There is a need to understand the coupled biogeochemical and hydrological processes that control stream hydrochemistry in upland forested catchments. At watershed 9 (W-9) of the Sleepers River Research Watershed in the northeastern USA, we use high-frequency sampling, environmental tracers, end-member mixing analysis, and stream reach mass balances to understand dynamic factors affect forms and concentrations of nitrogen and organic matter in streamflow. We found that rates of stream nitrate processing changed during autumn baseflow and that up to 70% of nitrate inputs to a stream reach were retained. At the same time, the stream reach was a net source of the dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) fractions of dissolved organic matter (DOM). The in-stream nitrate loss and DOM gains are examples of hot moments of biogeochemical transformations during autumn when deciduous litter fall increases DOM availability. As hydrological flowpaths changed during rainfall events, the sources and transformations of nitrate and DOM differed from baseflow. For example, during storm flow we measured direct inputs of unprocessed atmospheric nitrate to streams that were as large as 30% of the stream nitrate loading. At the same time, stream DOM composition shifted to reflect inputs of reactive organic matter from surficial upland soils. The transport of atmospheric nitrate and reactive DOM to streams underscores the importance of quantifying source variation during short-duration stormflow events. Building upon these findings we present a conceptual model of interacting ecosystem processes that control the flow of water and nutrients to streams in a temperate upland catchment.

Focused attention in a simple dichotic listening task: an fMRI experiment.

PubMed

Jäncke, Lutz; Specht, Karsten; Shah, Joni Nadim; Hugdahl, Kenneth

2003-04-01

Whole-head functional magnetic resonance imaging (fMRI) was used in nine neurologically intact subjects to measure the hemodynamic responses in the context of dichotic listening (DL). In order to eliminate the influence of verbal information processing, tones of different frequencies were used as stimuli. Three different dichotic listening tasks were used: the subjects were instructed to either concentrate on the stimuli presented in both ears (DIV), or only in the left (FL) or right (FR) ear and to monitor the auditory input for a specific target tone. When the target tone was detected, the subjects were required to indicate this by pressing a response button. Compared to the resting state, all dichotic listening tasks evoked strong hemodynamic responses within a distributed network comprising of temporal, parietal, and frontal brain areas. Thus, it is clear that dichotic listening makes use of various cognitive functions located within the dorsal and ventral stream of auditory information processing (i.e., the 'what' and 'where' streams). Comparing the three different dichotic listening conditions with each other only revealed a significant difference in the pre-SMA and within the left planum temporale area. The pre-SMA was generally more strongly activated during the DIV condition than during the FR and FL conditions. Within the planum temporale, the strongest activation was found during the FR condition and the weakest during the DIV condition. These findings were taken as evidence that even a simple dichotic listening task such as the one used here, makes use of a distributed neural network comprising of the dorsal and ventral stream of auditory information processing. In addition, these results support the previously made assumption that planum temporale activation is modulated by attentional strategies. Finally, the present findings uncovered that the pre-SMA, which is mostly thought to be involved in higher-order motor control processes, is also involved in cognitive processes operative during dichotic listening.

System for processing an encrypted instruction stream in hardware

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

Griswold, Richard L.; Nickless, William K.; Conrad, Ryan C.

A system and method of processing an encrypted instruction stream in hardware is disclosed. Main memory stores the encrypted instruction stream and unencrypted data. A central processing unit (CPU) is operatively coupled to the main memory. A decryptor is operatively coupled to the main memory and located within the CPU. The decryptor decrypts the encrypted instruction stream upon receipt of an instruction fetch signal from a CPU core. Unencrypted data is passed through to the CPU core without decryption upon receipt of a data fetch signal.

Development of rapid methods for measuring stream ecosystem functions in the Appalachian coal mining region: preliminary results

EPA Science Inventory

Headwater streams represent the majority of U.S. stream miles. As a consequence of being abundant and widespread, the alteration and loss of headwater streams may have impacts on downstream waterbodies. These streams are frequently the subject of proposed dredge and fill projects...

StreamWorks: the live and on-demand audio/video server and its applications in medical information systems

NASA Astrophysics Data System (ADS)

Akrout, Nabil M.; Gordon, Howard; Palisson, Patrice M.; Prost, Remy; Goutte, Robert

1996-05-01

Facing a world undergoing fundamental and rapid change, healthcare organizations are seeking ways to increase innovation, quality, productivity, and patient value, keys to more effective care. Individual clinics acting alone can respond in only a limited way, so re- engineering the process key which services are delivered demands real-time collaborative technology that provides immediate information sharing, improving the management and coordination of information in cross-functional teams. StreamWorks is a development stage architecture that uses a distribution technique to deliver an advanced information management system for telemedicine. The challenge of StreamWorks in telemedicine is to enable equity of the quality of Health Care of Telecommunications and Information Technology also to patients in less favored regions, like India or China, where the quality of medical care varies greatly by region, but where there are some very current communications facilities.

Temperature Response of a Small Mountain Stream to Thunderstorm Cloud-Cover: Application of DTS Fiber-Optic Temperature Sensing

NASA Astrophysics Data System (ADS)

Thayer, D.; Klatt, A. L.; Miller, S. N.; Ohara, N.

2014-12-01

From a hydrologic point of view, the critical zone in alpine areas contains the first interaction of living systems with water which will flow to streams and rivers that sustain lowland biomes and human civilization. A key to understanding critical zone functions is understanding the flow of energy, and we can measure temperature as a way of looking at energy transfer between related systems. In this study we installed a Distributed Temperature Sensor (DTS) and fiber-optic cable in a zero-order stream at 9,000 ft in the Medicine Bow National Forest in southern Wyoming. We measured the temperature of the stream for 17 days from June 29 to July 16; the first 12 days were mostly sunny with occasional afternoon storms, and the last 5 experienced powerful, long-lasting storms for much of the day. The DTS measurements show a seasonal warming trend of both minimum and maximum stream temperature for the first 12 days, followed by a distinct cooling trend for the five days that experienced heavy storm activity. To gain insights into the timing and mechanisms of energy flow through the critical zone systems, we analyzed the timing of stream temperature change relative to solar short-wave radiation, and compared the stream temperature temporal response to the temporal response of soil temperature adjacent to the stream. Since convective thunderstorms are a dominant summer weather pattern in sub-alpine regions in the Rocky Mountains, this study gives us further insight into interactions of critical zone processes and weather in mountain ecosystems.

Comparison of drinking water treatment process streams for optimal bacteriological water quality.

PubMed

Ho, Lionel; Braun, Kalan; Fabris, Rolando; Hoefel, Daniel; Morran, Jim; Monis, Paul; Drikas, Mary

2012-08-01

Four pilot-scale treatment process streams (Stream 1 - Conventional treatment (coagulation/flocculation/dual media filtration); Stream 2 - Magnetic ion exchange (MIEX)/Conventional treatment; Stream 3 - MIEX/Conventional treatment/granular activated carbon (GAC) filtration; Stream 4 - Microfiltration/nanofiltration) were commissioned to compare their effectiveness in producing high quality potable water prior to disinfection. Despite receiving highly variable source water quality throughout the investigation, each stream consistently reduced colour and turbidity to below Australian Drinking Water Guideline levels, with the exception of Stream 1 which was difficult to manage due to the reactive nature of coagulation control. Of particular interest was the bacteriological quality of the treated waters where flow cytometry was shown to be the superior monitoring tool in comparison to the traditional heterotrophic plate count method. Based on removal of total and active bacteria, the treatment process streams were ranked in the order: Stream 4 (average log removal of 2.7) > Stream 2 (average log removal of 2.3) > Stream 3 (average log removal of 1.5) > Stream 1 (average log removal of 1.0). The lower removals in Stream 3 were attributed to bacteria detaching from the GAC filter. Bacterial community analysis revealed that the treatments affected the bacteria present, with the communities in streams incorporating conventional treatment clustering with each other, while the community composition of Stream 4 was very different to those of Streams 1, 2 and 3. MIEX treatment was shown to enhance removal of bacteria due to more efficient flocculation which was validated through the novel application of the photometric dispersion analyser. Copyright © 2012 Elsevier Ltd. All rights reserved.

Validation of a stream and riparian habitat assessment protocol using stream salamanders in the southwest Virginia coalfields

USGS Publications Warehouse

Sweeten, Sara E.; Ford, W. Mark

2016-01-01

Within the central Appalachia Coalfields, the aquatic impacts of large-scale land uses, such as surface mining, are of particular ecological concern. Identification and quantification of land use impacts to aquatic ecosystems are a necessary first step to aid in mitigation of negative consequences to biota. However, quantifying physical environmental quality such as stream and riparian habitat often can be quite difficult, particularly when there is time or fiscal limitations. As such, standard protocols such as the U.S. EPA’s Stream Habitat Rapid Bioassessment Protocol have been established to be cost- and time-effective. This protocol estimates ten different stream and riparian conditions on a scale of 0 to 20. Unfortunately, using estimations can be problematic because of large potential variation in the scoring depending on differences in training, experience, and opinion of the personnel doing the estimations. In order to help negate these biases and provide a simplified process, the U.S. Army Corps of Engineers (USACE) developed a functional assessment for streams that measures 11 stream and riparian variables along with watershed land use to calculate three different scores, a hydrology score, biogeochemical score, and habitat score. In our study, we examined the correlation of stream salamander presence and abundance to the three USACE scores. In the summer of 2013, we visited 70 sites in the southwest Virginia Coalfields multiple times to collect salamanders and quantify stream and riparian microhabitat parameters. Using occupancy and abundance analyses, we found strong relationships among three Desmognathus spp. and the USACE Habitat FCI score. Accordingly, the Habitat FCI score provides a reasonable assessment of physical instream and riparian conditions that may serve as a surrogate for understanding the community composition and integrity of aquatic salamander in the region.

Restoring hydrological and biogeochemical ecosystem services in streams: how can science inform practice?

NASA Astrophysics Data System (ADS)

Lautz, L.; Gordon, R.; Daniluk, T.; Zimmer, M. A.; Endreny, T. A.; McGrath, K.

2014-12-01

Society is increasingly recognizing the value of stream ecosystem functions, as evidenced by the enormous economic investment being made in stream restoration across the United States. Stream restoration projects have a variety of goals, including improvement in water quality and in-stream habitat. Popular approaches to restoration (such as Natural Channel Design, or NCD) aim to move degraded streams along a trajectory toward a dynamic ecological endpoint that represents natural conditions. Project designs primarily focus on channel form and function, but stream-groundwater exchanges of water and solutes are not typically a design consideration, although a primary component of fully functioning stream ecosystems. Here, we synthesize results from field investigations of the impact of NCD stream restoration on stream-groundwater exchanges by (1) comparing restored sites to reference reaches, which serve as the basis for the restoration design, (2) characterizing multiple restored sites to determine universal characteristics of streams restored by NCD, and (3) monitoring a stream pre- and post- restoration. NCD restoration creates hot spots of rapid hyporheic exchange upstream of channel spanning structures, with water fluxes across the bed interface up to an order of magnitude higher than at pre-restoration or reference reaches. Elevated flux rates result in short hyporheic residence times, which are not sufficiently long to generate net changes in nutrient concentrations. Hot spots of biogeochemical transformations are instead located around secondary bedforms, such as pool-riffle sequences, where gross water exchange rates are more moderate. Reference reaches show greater evidence of groundwater discharge to the hyporheic zone relative to restored reaches, although observations before and after restoration suggest NCD can modify the spatial extent of groundwater discharge zones. Gross water exchange across the streambed interface along restored reaches is a small percentage of stream discharge, suggesting the primary impact of restoration on stream-groundwater exchange is promoting biochemical heterogeneity in the subsurface, rather than longitudinal net changes in stream solute concentrations. Results inform future design to achieve restoration goals.

Multispectral Imaging Broadens Cellular Analysis

NASA Technical Reports Server (NTRS)

2007-01-01

Amnis Corporation, a Seattle-based biotechnology company, developed ImageStream to produce sensitive fluorescence images of cells in flow. The company responded to an SBIR solicitation from Ames Research Center, and proposed to evaluate several methods of extending the depth of field for its ImageStream system and implement the best as an upgrade to its commercial products. This would allow users to view whole cells at the same time, rather than just one section of each cell. Through Phase I and II SBIR contracts, Ames provided Amnis the funding the company needed to develop this extended functionality. For NASA, the resulting high-speed image flow cytometry process made its way into Medusa, a life-detection instrument built to collect, store, and analyze sample organisms from erupting hydrothermal vents, and has the potential to benefit space flight health monitoring. On the commercial end, Amnis has implemented the process in ImageStream, combining high-resolution microscopy and flow cytometry in a single instrument, giving researchers the power to conduct quantitative analyses of individual cells and cell populations at the same time, in the same experiment. ImageStream is also built for many other applications, including cell signaling and pathway analysis; classification and characterization of peripheral blood mononuclear cell populations; quantitative morphology; apoptosis (cell death) assays; gene expression analysis; analysis of cell conjugates; molecular distribution; and receptor mapping and distribution.

Electrokinetic instability micromixing.

PubMed

Oddy, M H; Santiago, J G; Mikkelsen, J C

2001-12-15

We have developed an electrokinetic process to rapidly stir micro- and nanoliter volume solutions for microfluidic bioanalytical applications. We rapidly stir microflow streams by initiating a flow instability, which we have observed in sinusoidally oscillating, electroosmotic channel flows. As the effect occurs within an oscillating electroosmotic flow, we refer to it here as an electrokinetic instability (EKI). The rapid stretching and folding of material lines associated with this instability can be used to stir fluid streams with Reynolds numbers of order unity, based on channel depth and rms electroosmotic velocity. This paper presents a preliminary description of the EKI and the design and fabrication of two micromixing devices capable of rapidly stirring two fluid streams using this flow phenomenon. A high-resolution CCD camera is used to record the stirring and diffusion of fluorescein from an initially unmixed configuration. Integration of fluorescence intensity over measurement volumes (voxels) provides a measure of the degree to which two streams are mixed to within the length scales of the voxels. Ensemble-averaged probability density functions and power spectra of the instantaneous spatial intensity profiles are used to quantify the mixing processes. Two-dimensional spectral bandwidths of the mixing images are initially anisotropic for the unmixed configuration, broaden as the stirring associated with the EKI rapidly stretches and folds material lines (adding high spatial frequencies to the concentration field), and then narrow to a relatively isotropic spectrum at the well-mixed conditions.

Variation of organic matter quantity and quality in streams at Critical Zone Observatory watersheds

USGS Publications Warehouse

Miller, Matthew P.; Boyer, Elizabeth W.; McKnight, Diane M.; Brown, Michael G.; Gabor, Rachel S.; Hunsaker, Carolyn T.; Iavorivska , Lidiia; Inamdar, Shreeram; Kaplan, Louis A.; Johnson, Dale W.; Lin, Henry; McDowell, William H.; Perdrial, Julia N.

2016-01-01

The quantity and chemical composition of dissolved organic matter (DOM) in surface waters influence ecosystem processes and anthropogenic use of freshwater. However, despite the importance of understanding spatial and temporal patterns in DOM, measures of DOM quality are not routinely included as part of large-scale ecosystem monitoring programs and variations in analytical procedures can introduce artifacts. In this study, we used consistent sampling and analytical methods to meet the objective of defining variability in DOM quantity and quality and other measures of water quality in streamflow issuing from small forested watersheds located within five Critical Zone Observatory sites representing contrasting environmental conditions. Results show distinct separations among sites as a function of water quality constituents. Relationships among rates of atmospheric deposition, water quality conditions, and stream DOM quantity and quality are consistent with the notion that areas with relatively high rates of atmospheric nitrogen and sulfur deposition and high concentrations of divalent cations result in selective transport of DOM derived from microbial sources, including in-stream microbial phototrophs. We suggest that the critical zone as a whole strongly influences the origin, composition, and fate of DOM in streams. This study highlights the value of consistent DOM characterization methods included as part of long-term monitoring programs for improving our understanding of interactions among ecosystem processes as controls on DOM biogeochemistry.

Redesigning emergency department patient flows: application of Lean Thinking to health care.

PubMed

King, Diane L; Ben-Tovim, David I; Bassham, Jane

2006-08-01

To describe in some detail the methods used and outcome of an application of concepts from Lean Thinking in establishing streams for patient flows in a teaching general hospital ED. Detailed understanding was gained through process mapping with staff followed by the identification of value streams (those patients likely to be discharged from the ED, those who were likely to be admitted) and the implementation of a process of seeing those patients that minimized complex queuing in the ED. Streaming had a significant impact on waiting times and total durations of stay in the ED. There was a general flattening of the waiting time across all groups. A slight increase in wait for Triage categories 2 and 3 patients was offset by reductions in wait for Triage category 4 patients. All groups of patients spent significantly less overall time in the department and the average number of patients in the ED at any time decreased. There was a significant reduction in number of patients who do not wait and a slight decrease in access block. The streaming of patients into groups of patients cared for by a specific team of doctors and nurses, and the minimizing of complex queues in this ED by altering the practices in relation to the function of the Australasian Triage Scale improved patient flow, thereby decreasing potential for overcrowding.

A new approach to flow through a region bounded by two ellipses of the same ellipticity

NASA Astrophysics Data System (ADS)

Lal, K.; Chorlton, F.

1981-05-01

A new approach is presented to calculate steady flow of a laminar viscous incompressible fluid through a channel whose cross section is bounded by two ellipses with the same ellipticity. The Milne-Thomas approach avoids the stream function and is similar to the Rayleigh-Ritz approximation process of the calculus of variations in its first satisfying boundary conditions and then adjusting constants or multiplying functions to fit the differential equation.

Machine vision system for automated detection of stained pistachio nuts

NASA Astrophysics Data System (ADS)

Pearson, Tom C.

1995-01-01

A machine vision system was developed to separate stained pistachio nuts, which comprise of about 5% of the California crop, from unstained nuts. The system may be used to reduce labor involved with manual grading or to remove aflatoxin contaminated product from low grade process streams. The system was tested on two different pistachio process streams: the bi- chromatic color sorter reject stream and the small nut shelling stock stream. The system had a minimum overall error rate of 14% for the bi-chromatic sorter reject stream and 15% for the small shelling stock stream.

Ammonia Monitor

NASA Technical Reports Server (NTRS)

Sauer, Richard L. (Inventor); Akse, James R. (Inventor); Thompson, John O. (Inventor); Atwater, James E. (Inventor)

1999-01-01

Ammonia monitor and method of use are disclosed. A continuous, real-time determination of the concentration of ammonia in an aqueous process stream is possible over a wide dynamic range of concentrations. No reagents are required because pH is controlled by an in-line solid-phase base. Ammonia is selectively transported across a membrane from the process stream to an analytical stream to an analytical stream under pH control. The specific electrical conductance of the analytical stream is measured and used to determine the concentration of ammonia.

The behaviour of 39 pesticides in surface waters as a function of scale

USGS Publications Warehouse

Capel, P.D.; Larson, S.J.; Winterstein, T.A.

2001-01-01

A portion of applied pesticides runs off agricultural fields and is transported through surface waters. In this study, the behaviour of 39 pesticides is examined as a function of scale across 14 orders of magnitude from the field to the ocean. Data on pesticide loads in streams from two US Geological Survey programs were combined with literature data from field and watershed studies. The annual load as percent of use (LAPU) was quantified for each of the fields and watersheds and was used as the normalization factor across watersheds and compounds. The in-stream losses of each pesticide were estimated for a model stream with a 15 day travel time (similar in characteristics to the upper Mississippi River). These estimated in-stream losses agreed well with the observed changes in apparent LAPU values as a function of watershed area. In general, herbicides applied to the soil surface had the greatest LAPU values and minimal in-stream losses. Soil-incorporated herbicides had smaller LAPU values and substantial in-stream losses. Insecticides generally had LAPU values similar to the incorporated herbicides, but had more variation in their in-stream losses. On the basis of the LAPU values of the 39 pesticides as a function of watershed area, a generalized conceptual model of the movement of pesticides from the field to the ocean is suggested. The importance of considering both field runoff and in-stream losses is discussed in relation to interpreting monitoring data and making regulatory decisions.

Mass, energy and material balances of SRF production process. Part 2: SRF produced from construction and demolition waste.

PubMed

Nasrullah, Muhammad; Vainikka, Pasi; Hannula, Janne; Hurme, Markku; Kärki, Janne

2014-11-01

In this work, the fraction of construction and demolition waste (C&D waste) complicated and economically not feasible to sort out for recycling purposes is used to produce solid recovered fuel (SRF) through mechanical treatment (MT). The paper presents the mass, energy and material balances of this SRF production process. All the process streams (input and output) produced in MT waste sorting plant to produce SRF from C&D waste are sampled and treated according to CEN standard methods for SRF. Proximate and ultimate analysis of these streams is performed and their composition is determined. Based on this analysis and composition of process streams their mass, energy and material balances are established for SRF production process. By mass balance means the overall mass flow of input waste material stream in the various output streams and material balances mean the mass flow of components of input waste material stream (such as paper and cardboard, wood, plastic (soft), plastic (hard), textile and rubber) in the various output streams of SRF production process. The results from mass balance of SRF production process showed that of the total input C&D waste material to MT waste sorting plant, 44% was recovered in the form of SRF, 5% as ferrous metal, 1% as non-ferrous metal, and 28% was sorted out as fine fraction, 18% as reject material and 4% as heavy fraction. The energy balance of this SRF production process showed that of the total input energy content of C&D waste material to MT waste sorting plant, 74% was recovered in the form of SRF, 16% belonged to the reject material and rest 10% belonged to the streams of fine fraction and heavy fraction. From the material balances of this process, mass fractions of plastic (soft), paper and cardboard, wood and plastic (hard) recovered in the SRF stream were 84%, 82%, 72% and 68% respectively of their input masses to MT plant. A high mass fraction of plastic (PVC) and rubber material was found in the reject material stream. Streams of heavy fraction and fine fraction mainly contained non-combustible material (such as stone/rock, sand particles and gypsum material). Copyright © 2014 Elsevier Ltd. All rights reserved.

Stream ecosystem integrity is impaired by logging and shifting agriculture in a global megadiversity center (Sarawak, Borneo).

PubMed

Jinggut, Tajang; Yule, Catherine M; Boyero, Luz

2012-10-15

In common with most of Borneo, the Bakun region of Sarawak is currently subject to heavy deforestation mainly due to logging and, to a lesser extent, traditional slash-and-burn farming practices. This has the potential to affect stream ecosystems, which are integrators of environmental change in the surrounding terrestrial landscape. This study evaluated the effects of both types of deforestation by using functional and structural indicators (leaf litter decomposition rates and associated detritivores or 'shredders', respectively) to compare a fundamental ecosystem process, leaf litter decomposition, within logged, farmed and pristine streams. Slash-and-burn agricultural practices increased the overall rate of decomposition despite a decrease in shredder species richness (but not shredder abundance) due to increased microbial decomposition. In contrast, decomposition by microbes and invertebrates was slowed down in the logged streams, where shredders were less abundant and less species rich. This study suggests that shredder communities are less affected by traditional agricultural farming practices, while modern mechanized deforestation has an adverse effect on both shredder communities and leaf breakdown. Copyright © 2012 Elsevier B.V. All rights reserved.

Development of a multimetric index based on benthic macroinvertebrates for the assessment of urban stream health in Jinan City, China.

PubMed

Liu, Linfei; Xu, Zongxue; Yin, Xuwang; Li, Fulin; Dou, Tongwen

2017-05-01

Assessment of the health of urban streams is an important theoretical and practical topic, which is related to the impacts of physiochemical processes, hydrological modifications, and the biological community. However, previous assessments of the urban water quality were predominantly conducted by measuring physical and chemical factors rather than biological monitoring. The purpose of this study was to develop an urban stream multimetric index (USMI) based on benthic macroinvertebrates to assess the health of aquatic ecosystem in Jinan City. Two hundred and eighty-eight samples were collected during two consecutive years (2014-2015) from 48 sites located within the city. Metrics related to the benthic macroinvertebrate richness, diversity, composition and abundance, and functional feeding groups were selected by using box-plots and the Kruskal-Wallis test. The final index derived from selected metrics was divided into five river quality classes (excellent, good, moderate, poor, and bad). A validation procedure using box-plots and the non-parametric Mann-Whitney U test showed that the USMI was useful to assess the health of urban streams.

Hydrology of Channelized and Natural Headwater Streams

USDA-ARS?s Scientific Manuscript database

Understanding hydrology is paramount for optimal ecologic function and management of headwater streams. The objective of this study was to characterize and compare headwater streams within the Upper Big Walnut Creek watershed in Ohio. Two channelized and two unchannelized streams were instrumented w...

Efficient gas-separation process to upgrade dilute methane stream for use as fuel

DOEpatents

Wijmans, Johannes G [Menlo Park, CA; Merkel, Timothy C [Menlo Park, CA; Lin, Haiqing [Mountain View, CA; Thompson, Scott [Brecksville, OH; Daniels, Ramin [San Jose, CA

2012-03-06

A membrane-based gas separation process for treating gas streams that contain methane in low concentrations. The invention involves flowing the stream to be treated across the feed side of a membrane and flowing a sweep gas stream, usually air, across the permeate side. Carbon dioxide permeates the membrane preferentially and is picked up in the sweep air stream on the permeate side; oxygen permeates in the other direction and is picked up in the methane-containing stream. The resulting residue stream is enriched in methane as well as oxygen and has an EMC value enabling it to be either flared or combusted by mixing with ordinary air.

Platinum recovery from industrial process streams by halophilic bacteria: Influence of salt species and platinum speciation.

PubMed

Maes, Synthia; Claus, Mathias; Verbeken, Kim; Wallaert, Elien; De Smet, Rebecca; Vanhaecke, Frank; Boon, Nico; Hennebel, Tom

2016-11-15

The increased use and criticality of platinum asks for the development of effective low-cost strategies for metal recovery from process and waste streams. Although biotechnological processes can be applied for the valorization of diluted aqueous industrial streams, investigations considering real stream conditions (e.g., high salt levels, acidic pH, metal speciation) are lacking. This study investigated the recovery of platinum by a halophilic microbial community in the presence of increased salt concentrations (10-80 g L -1 ), different salt matrices (phosphate salts, sea salts and NH 4 Cl) and a refinery process stream. The halophiles were able to recover 79-99% of the Pt at 10-80 g L -1 salts and at pH 2.3. Transmission electron microscopy suggested a positive correlation between intracellular Pt cluster size and elevated salt concentrations. Furthermore, the halophiles recovered 46-95% of the Pt-amine complex Pt[NH 3 ] 4 2+ from a process stream after the addition of an alternative Pt source (K 2 PtCl 4 , 0.1-1.0 g L -1 Pt). Repeated Pt-tetraamine recovery (from an industrial process stream) was obtained after concomitant addition of fresh biomass and harvesting of Pt saturated biomass. This study demonstrates how aqueous Pt streams can be transformed into Pt rich biomass, which would be an interesting feed of a precious metals refinery. Copyright © 2016 Elsevier Ltd. All rights reserved.

Small stream ecosystem variability in the Sierra Nevada of California

Treesearch

C.T. Hunsaker; S.M. Eagan

2003-01-01

The quality of aquatic and riparian ecosystems is a function of their condition and the integrity of adjacent uplands in their watersheds. While small streams make up a large proportion of the overall stream network, our knowledge of how they function is still limited. The Kings River Experimental Watershed (KREW) was initiated in 2000 to quantify the variability in...

Light availability impacts structure and function of phototrophic stream biofilms across domains and trophic levels.

PubMed

Bengtsson, Mia M; Wagner, Karoline; Schwab, Clarissa; Urich, Tim; Battin, Tom J

2018-04-21

Phototrophic biofilms are ubiquitous in freshwater and marine environments where they are critical for biogeochemical cycling, food webs and in industrial applications. In streams, phototrophic biofilms dominate benthic microbial life and harbor an immense prokaryotic and eukaryotic microbial biodiversity with biotic interactions across domains and trophic levels. Here, we examine how community structure and function of these biofilms respond to varying light availability, as the crucial energy source for phototrophic biofilms. Using metatranscriptomics, we found that under light limitation dominant phototrophs, including diatoms and cyanobacteria, displayed a remarkable plasticity in their photosynthetic machinery manifested as higher abundance of messenger RNAs (mRNAs) involved in photosynthesis and chloroplast ribosomal RNA. Under higher light availability, bacterial mRNAs involved in phosphorus metabolism, mainly from Betaproteobacteria and Cyanobacteria, increased, likely compensating for nutrient depletion in thick biofilms with high biomass. Consumers, including diverse ciliates, displayed community shifts indicating preferential grazing on algae instead of bacteria under higher light. For the first time, we show that the functional integrity of stream biofilms under variable light availability is maintained by structure-function adaptations on several trophic levels. Our findings shed new light on complex biofilms, or "microbial jungles", where in analogy to forests, diverse and multi-trophic level communities lend stability to ecosystem functioning. This multi-trophic level perspective, coupling metatranscriptomics to process measurements, could advance understanding of microbial-driven ecosystems beyond biofilms, including planktonic and soil environments. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Isolation and characterization of new lignin streams derived from extractive-ammonia (EA) pretreatment

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

da Costa Sousa, Leonardo; Foston, Marcus; Bokade, Vijay

One of the key challenges facing lignin conversion to fuels and chemicals is related to the level of carbohydrate and ash impurities found in extracted lignin. Structural modifications of lignin may also occur as a result of biomass pretreatment and harsh lignin extraction protocols. Extractive-Ammonia (EA) is a new pretreatment technology that uses liquid ammonia to cleave lignin–carbohydrate complexes, decrystallize cellulose, solubilize lignin, and selectively extract lignin from lignocellulosic biomass, enabling better utilization of both lignin and carbohydrate components in a biorefinery. The EA-based biorefinery produces two different lignin-rich streams, with different properties, that could potentially be upgraded to fuelsmore » and chemicals using green processes. Here, a water/ethanol-based fractionation method was developed to enrich the ammonia-soluble extractives, resulting in a major product stream containing 92% lignin. Detailed characterization of the various streams resulting from EA treatment, including compositional analysis, structural characterization by nuclear magnetic resonance (NMR) spectrometry, elemental analysis, molecular weight analysis, and thermo-gravimetric analysis provides a broad evaluation of the EA-derived lignin product stream structures and properties, assessing their potential for commercial applications. In conclusion, EA-derived lignins preserve much of lignin's functionality, including the sensitive β-aryl ether units. Furthermore, we observed nitrogen incorporation in the lignin-rich streams, notably due to the presence of hydroxycinnamoyl amides formed during ammonia pretreatment.« less

Determination of hyporheic travel time distributions and other parameters from concurrent conservative and reactive tracer tests by local-in-global optimization

NASA Astrophysics Data System (ADS)

Knapp, Julia L. A.; Cirpka, Olaf A.

2017-06-01

The complexity of hyporheic flow paths requires reach-scale models of solute transport in streams that are flexible in their representation of the hyporheic passage. We use a model that couples advective-dispersive in-stream transport to hyporheic exchange with a shape-free distribution of hyporheic travel times. The model also accounts for two-site sorption and transformation of reactive solutes. The coefficients of the model are determined by fitting concurrent stream-tracer tests of conservative (fluorescein) and reactive (resazurin/resorufin) compounds. The flexibility of the shape-free models give rise to multiple local minima of the objective function in parameter estimation, thus requiring global-search algorithms, which is hindered by the large number of parameter values to be estimated. We present a local-in-global optimization approach, in which we use a Markov-Chain Monte Carlo method as global-search method to estimate a set of in-stream and hyporheic parameters. Nested therein, we infer the shape-free distribution of hyporheic travel times by a local Gauss-Newton method. The overall approach is independent of the initial guess and provides the joint posterior distribution of all parameters. We apply the described local-in-global optimization method to recorded tracer breakthrough curves of three consecutive stream sections, and infer section-wise hydraulic parameter distributions to analyze how hyporheic exchange processes differ between the stream sections.

Slope failure as an upslope source of stream wood

Treesearch

Daniel Miller

2013-01-01

Large woody debris is recognized as an important component of stream geomorphology and stream ecosystem function, and forest-land management is recognized as an important control on the quantity (and size and species distributions) of wood available for recruitment to streams. Much of the wood present in streams comes from adjacent forests, and riparian management...

Two stroke engine exhaust emissions separator

DOEpatents

Turner, Terry D.; Wilding, Bruce M.; McKellar, Michael G.; Raterman, Kevin T.

2003-04-22

A separator for substantially resolving at least one component of a process stream, such as from the exhaust of an internal combustion engine. The separator includes a body defining a chamber therein. A nozzle housing is located proximate the chamber. An exhaust inlet is in communication with the nozzle housing and the chamber. A nozzle assembly is positioned in the nozzle housing and includes a nozzle moveable within and relative to the nozzle housing. The nozzle includes at least one passage formed therethrough such that a process stream entering the exhaust inlet connection passes through the passage formed in the nozzle and imparts a substantially rotational flow to the process stream as it enters the chamber. A positioning member is configured to position the nozzle relative to the nozzle housing in response to changes in process stream pressure thereby adjusting flowrate of said process stream entering into the chamber.

Two stroke engine exhaust emissions separator

DOEpatents

Turner, Terry D.; Wilding, Bruce M.; McKellar, Michael G.; Raterman, Kevin T.

2002-01-01

A separator for substantially resolving at least one component of a process stream, such as from the exhaust of an internal combustion engine. The separator includes a body defining a chamber therein. A nozzle housing is located proximate the chamber. An exhaust inlet is in communication with the nozzle housing and the chamber. A nozzle assembly is positioned in the nozzle housing and includes a nozzle moveable within and relative to the nozzle housing. The nozzle includes at least one passage formed therethrough such that a process stream entering the exhaust inlet connection passes through the passage formed in the nozzle, which imparts a substantially rotational flow to the process stream as it enters the chamber. A positioning member is configured to position the nozzle relative to the nozzle housing in response to changes in process stream pressure to adjust flowrate of said process stream entering into the chamber.

Effects of Large Wood on River-Floodplain Connectivity in a Headwater Appalachian Stream

NASA Astrophysics Data System (ADS)

Keys, T.; Govenor, H.; Jones, C. N.; Hession, W. C.; Scott, D.; Hester, E. T.

2017-12-01

Large wood (LW) plays an important, yet often undervalued role in stream ecosystems. Traditionally, LW has been removed from streams for aesthetic, navigational, and flood mitigation purposes. However, extensive research over the last three decades has directly linked LW to critical ecosystem functions including habitat provisioning, stream geomorphic stability, and water quality improvements; and as such, LW has increasingly been implemented in stream restoration activities. One of the proposed benefits to this restoration approach is that LW increases river-floodplain connectivity, potentially decreasing downstream flood peaks and improving water quality. Here, we conducted two experiential floods (i.e., one with and one without LW) in a headwater, agricultural stream to explore the effect of LW on river-floodplain connectivity and resulting hydrodynamic processes. During each flood, we released an equal amount of water to the stream channel, measured stream discharge at upstream and downstream boundaries, and measured inundation depth at multiple locations across the floodplain. We then utilized a 2-dimensional hydrodynamic model (HEC-RAS) to simulate floodplain hydrodynamics. We first calibrated the model using observations from the two experimental floods. Then, we utilized the calibrated model to evaluate differing LW placement strategies and effects under various flow conditions. Results show that the addition of LW to the channel decreased channel velocity and increased inundation extent, inundation depth, and floodplain velocity. Differential placement of LW along the stream impacted the levels of floodplain discharge, primarily due to the geomorphic characteristics of the stream. Finally, we examined the effects of LW on floodplain hydrodynamics across a synthetic flow record, and found that the magnitude of river-floodplain connectivity decreased as recurrence interval increased, with limited impacts on storm events with a recurrence interval of 25 years or greater. These findings suggest that LW plays a substantial role in river-floodplain connectivity of headwater streams and associated ecosystem services.

Leaf Litter Decomposition as a Functional Assessment of a Natural Stream Channel Design Project

NASA Astrophysics Data System (ADS)

Gentry, A.; Word, D.; Carreiro, M.; Jack, J.

2005-05-01

In October 2003, a 965m reach of Wilson Creek (Bernheim Research Forest, Kentucky, USA) was relocated, and meanders and riffle-pool sequences were restored, providing a unique opportunity to measure the re-establishment of post-restoration stream functions. Leaf litter bags were placed across riffles in the restored reach, in an upstream reference site and in two reference streams. Bags were collected for nine months, and mass loss, N dynamics and fungal ergosterol were measured. Daily mass loss rates in the restored and reference riffles in Wilson Creek were faster (k= -0.00759 and k= -0.00855, respectively) than those of the two reference streams (k= -0.00511 and k= -0.00308). This is equivalent to litter mean residence times of 132 days for the restored reach in Wilson, 117 days in the upstream reference site, and 196 and 325 days for the reference streams. It appears that the decay rate in the restored reach is similar to the upstream portion of Wilson Creek, indicating rapid mass loss recovery in the restored reach. We also determined that same-stream reference sites are important for evaluating the restoration of stream functions, because of high decay rate variation among nearby streams within the same watershed.

DWPF RECYCLE EVAPORATOR FLOWSHEET EVALUATION (U)

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

Stone, M

2005-04-30

The Defense Waste Processing Facility (DWPF) converts the high level waste slurries stored at the Savannah River Site into borosilicate glass for long-term storage. The vitrification process results in the generation of approximately five gallons of dilute recycle streams for each gallon of waste slurry vitrified. This dilute recycle stream is currently transferred to the H-area Tank Farm and amounts to approximately 1,400,000 gallons of effluent per year. Process changes to incorporate salt waste could increase the amount of effluent to approximately 2,900,000 gallons per year. The recycle consists of two major streams and four smaller streams. The first majormore » recycle stream is condensate from the Chemical Process Cell (CPC), and is collected in the Slurry Mix Evaporator Condensate Tank (SMECT). The second major recycle stream is the melter offgas which is collected in the Off Gas Condensate Tank (OGCT). The four smaller streams are the sample flushes, sump flushes, decon solution, and High Efficiency Mist Eliminator (HEME) dissolution solution. These streams are collected in the Decontamination Waste Treatment Tank (DWTT) or the Recycle Collection Tank (RCT). All recycle streams are currently combined in the RCT and treated with sodium nitrite and sodium hydroxide prior to transfer to the tank farm. Tank Farm space limitations and previous outages in the 2H Evaporator system due to deposition of sodium alumino-silicates have led to evaluation of alternative methods of dealing with the DWPF recycle. One option identified for processing the recycle was a dedicated evaporator to concentrate the recycle stream to allow the solids to be recycled to the DWPF Sludge Receipt and Adjustment Tank (SRAT) and the condensate from this evaporation process to be sent and treated in the Effluent Treatment Plant (ETP). In order to meet process objectives, the recycle stream must be concentrated to 1/30th of the feed volume during the evaporation process. The concentrated stream must be pumpable to the DWPF SRAT vessel and should not precipitate solids to avoid fouling the evaporator vessel and heat transfer coils. The evaporation process must not generate excessive foam and must have a high Decontamination Factor (DF) for many species in the evaporator feed to allow the condensate to be transferred to the ETP. An initial scoping study was completed in 2001 to evaluate the feasibility of the evaporator which concluded that the concentration objectives could be met. This initial study was based on initial estimates of recycle concentration and was based solely on OLI modeling of the evaporation process. The Savannah River National Laboratory (SRNL) has completed additional studies using simulated recycle streams and OLI{reg_sign} simulations. Based on this work, the proposed flowsheet for the recycle evaporator was evaluated for feasibility, evaporator design considerations, and impact on the DWPF process. This work was in accordance with guidance from DWPF-E and was performed in accordance with the Technical Task and Quality Assurance Plan.« less

Significance of Thermal Fluvial Incision and Bedrock Transfer due to Ice Advection on Greenland Ice Sheet Topography

NASA Astrophysics Data System (ADS)

Crozier, J. A.; Karlstrom, L.; Yang, K.

2017-12-01

Ice sheet surface topography reflects a complicated combination of processes that act directly upon the surface and that are products of ice advection. Using recently-available high resolution ice velocity, imagery, ice surface elevation, and bedrock elevation data sets, we seek to determine the domain of significance of two important processes - thermal fluvial incision and transfer of bedrock topography through the ice sheet - on controlling surface topography in the ablation zone. Evaluating such controls is important for understanding how melting of the GIS surface during the melt season may be directly imprinted in topography through supraglacial drainage networks, and indirectly imprinted through its contribution to basal sliding that affects bedrock transfer. We use methods developed by (Karlstrom and Yang, 2016) to identify supraglacial stream networks on the GIS, and use high resolution surface digital elevation models as well as gridded ice velocity and melt rate models to quantify surface processes. We implement a numerically efficient Fourier domain bedrock transfer function (Gudmundsson, 2003) to predict surface topography due to ice advection over bedrock topography obtained from radar. Despite a number of simplifying assumptions, the bedrock transfer function predicts the observed ice sheet surface in most regions of the GIS with ˜90% accuracy, regardless of the presence or absence of supraglacial drainage networks. This supports the hypothesis that bedrock is the most significant driver of ice surface topography on wavelengths similar to ice thickness. Ice surface topographic asymmetry on the GIS is common, with slopes in the direction of ice flow steeper than those faced opposite to ice flow, consistent with bedrock transfer theory. At smaller wavelengths, topography consistent with fluvial erosion by surface hydrologic features is evident. We quantify the effect of ice advection versus fluvial thermal erosion on supraglacial longitudinal stream profiles, as a function of location on the GIS (hence ice thickness and background melt rate) using spectral techniques to quantify longitudinal stream profiles. This work should provide a predictive guide for which processes are responsible for ice sheet topography scales from several m (DEM resolution) up to several ice thicknesses.

Skill dependent audiovisual integration in the fusiform induces repetition suppression.

PubMed

McNorgan, Chris; Booth, James R

2015-02-01

Learning to read entails mapping existing phonological representations to novel orthographic representations and is thus an ideal context for investigating experience driven audiovisual integration. Because two dominant brain-based theories of reading development hinge on the sensitivity of the visual-object processing stream to phonological information, we were interested in how reading skill relates to audiovisual integration in this area. Thirty-two children between 8 and 13 years of age spanning a range of reading skill participated in a functional magnetic resonance imaging experiment. Participants completed a rhyme judgment task to word pairs presented unimodally (auditory- or visual-only) and cross-modally (auditory followed by visual). Skill-dependent sub-additive audiovisual modulation was found in left fusiform gyrus, extending into the putative visual word form area, and was correlated with behavioral orthographic priming. These results suggest learning to read promotes facilitatory audiovisual integration in the ventral visual-object processing stream and may optimize this region for orthographic processing. Copyright © 2014 Elsevier Inc. All rights reserved.

Skill Dependent Audiovisual Integration in the Fusiform Induces Repetition Suppression

PubMed Central

McNorgan, Chris; Booth, James R.

2015-01-01

Learning to read entails mapping existing phonological representations to novel orthographic representations and is thus an ideal context for investigating experience driven audiovisual integration. Because two dominant brain-based theories of reading development hinge on the sensitivity of the visual-object processing stream to phonological information, we were interested in how reading skill relates to audiovisual integration in this area. Thirty-two children between 8 and 13 years of age spanning a range of reading skill participated in a functional magnetic resonance imaging experiment. Participants completed a rhyme judgment task to word pairs presented unimodally (auditory- or visual-only) and cross-modally (auditory followed by visual). Skill-dependent sub-additive audiovisual modulation was found in left fusiform gyrus, extending into the putative visual word form area, and was correlated with behavioral orthographic priming. These results suggest learning to read promotes facilitatory audiovisual integration in the ventral visual-object processing stream and may optimize this region for orthographic processing. PMID:25585276

High rates of organic carbon processing in the hyporheic zone of intermittent streams.

PubMed

Burrows, Ryan M; Rutlidge, Helen; Bond, Nick R; Eberhard, Stefan M; Auhl, Alexandra; Andersen, Martin S; Valdez, Dominic G; Kennard, Mark J

2017-10-16

Organic carbon cycling is a fundamental process that underpins energy transfer through the biosphere. However, little is known about the rates of particulate organic carbon processing in the hyporheic zone of intermittent streams, which is often the only wetted environment remaining when surface flows cease. We used leaf litter and cotton decomposition assays, as well as rates of microbial respiration, to quantify rates of organic carbon processing in surface and hyporheic environments of intermittent and perennial streams under a range of substrate saturation conditions. Leaf litter processing was 48% greater, and cotton processing 124% greater, in the hyporheic zone compared to surface environments when calculated over multiple substrate saturation conditions. Processing was also greater in more saturated surface environments (i.e. pools). Further, rates of microbial respiration on incubated substrates in the hyporheic zone were similar to, or greater than, rates in surface environments. Our results highlight that intermittent streams are important locations for particulate organic carbon processing and that the hyporheic zone sustains this fundamental process even without surface flow. Not accounting for carbon processing in the hyporheic zone of intermittent streams may lead to an underestimation of its local ecological significance and collective contribution to landscape carbon processes.

Compensatory mitigation for streams under the Clean Water Act: reassessing science and redirecting policy

USDA-ARS?s Scientific Manuscript database

Considerable public funds are annually expended on stream restoration projects, but available science suggests that stream restoration as currently practiced is not effective in recovering ecosystem functional integrity. The physical scale of most stream restoration projects is insufficient because...

National and regional comparisons between Strahler order and stream size

EPA Science Inventory

Water body size is one of the most important factors affecting the structure and function of aquatic ecosystems. The categorical variable, Strahler stream order, is frequently used as an indirect estimate of stream size. Other indirect estimates of stream size, such as catchmen...

Do Visual Illusions Probe the Visual Brain?: Illusions in Action without a Dorsal Visual Stream

ERIC Educational Resources Information Center

Coello, Yann; Danckert, James; Blangero, Annabelle; Rossetti, Yves

2007-01-01

Visual illusions have been shown to affect perceptual judgements more so than motor behaviour, which was interpreted as evidence for a functional division of labour within the visual system. The dominant perception-action theory argues that perception involves a holistic processing of visual objects or scenes, performed within the ventral,…

Linking Changes in Management and Riparian Physical Functionality to Water Quality and Aquatic Habitat: A Case Study of Maggie Creek, NV

EPA Science Inventory

The total maximum daily load (TMDL) process is ineffective and inappropriate for improving stream water quality in the rural areas of the northern Great Basin, and likely in many areas throughout the country. Important pollutants (e.g., sediment and nutrients) come from the stre...

Biophysical Controls on Carbon Cycling in Restored and Unrestored Urban Streams

NASA Astrophysics Data System (ADS)

Larsen, L. G.; Harvey, J. W.; Singh, J. D.; Sinclair, G. A.; Langston, T.; Maglio, M. M.

2012-12-01

Stream restoration is a multibillion dollar industry, yet how restoration impacts the ecological functioning of streams remains poorly understood. Because stream restoration may alter numerous biophysical controls, including light availability (through tree removal during bank regrading), hydraulics, sediment characteristics, and/or nutrient concentrations, it can be challenging to achieve a general understanding of how different aspects of stream restoration design influence ecosystem function (e.g., carbon cycling). In this study we combined strategies of continuously monitoring hydrology, turbidity, and dissolved oxygen at a station with spatially distributed but temporally sparse synoptic sampling to understand how restoration and land-use impact carbon fixation and respiration in urban streams. The study was performed over three years in three adjacent 3rd-4th order stream reaches in the urban Chesapeake Bay watershed, one of which was restored in 2002 using the ubiquitous Natural Channel Design method. By parsing the dissolved oxygen time series into contributions from respiration and gross primary production, we found the unrestored urban reach to be the most heterotrophic. It removed two times more carbon from the stream to the atmosphere than an unrestored suburban stream that was nutrient impacted and five times more carbon than the restored urban stream. The synoptic sampling revealed that nutrients, light, and hydrodynamic disturbance were the primary controls on carbon fixation and respiration, with fine sediment also exhibiting importance, likely as a vehicle for nutrient transport. Low rates of net carbon removal in the restored stream arose from high light availability resulting in high primary production, combined with low fine sediment availability restricting respiration. Thus, while restoration may have been effective for stream stabilization, it has decreased the functionality of the stream for net carbon removal to the atmosphere. Surprisingly, streambed potential respiration rates were indistinguishable between different geomorphic zones within the streams, suggesting that large-scale factors (i.e., nutrient and fine sediment supply) were more dominant controls than geomorphically controlled local variability.

Where’s Waldo? How perceptual, cognitive, and emotional brain processes cooperate during learning to categorize and find desired objects in a cluttered scene

PubMed Central

Chang, Hung-Cheng; Grossberg, Stephen; Cao, Yongqiang

2014-01-01

The Where’s Waldo problem concerns how individuals can rapidly learn to search a scene to detect, attend, recognize, and look at a valued target object in it. This article develops the ARTSCAN Search neural model to clarify how brain mechanisms across the What and Where cortical streams are coordinated to solve the Where’s Waldo problem. The What stream learns positionally-invariant object representations, whereas the Where stream controls positionally-selective spatial and action representations. The model overcomes deficiencies of these computationally complementary properties through What and Where stream interactions. Where stream processes of spatial attention and predictive eye movement control modulate What stream processes whereby multiple view- and positionally-specific object categories are learned and associatively linked to view- and positionally-invariant object categories through bottom-up and attentive top-down interactions. Gain fields control the coordinate transformations that enable spatial attention and predictive eye movements to carry out this role. What stream cognitive-emotional learning processes enable the focusing of motivated attention upon the invariant object categories of desired objects. What stream cognitive names or motivational drives can prime a view- and positionally-invariant object category of a desired target object. A volitional signal can convert these primes into top-down activations that can, in turn, prime What stream view- and positionally-specific categories. When it also receives bottom-up activation from a target, such a positionally-specific category can cause an attentional shift in the Where stream to the positional representation of the target, and an eye movement can then be elicited to foveate it. These processes describe interactions among brain regions that include visual cortex, parietal cortex, inferotemporal cortex, prefrontal cortex (PFC), amygdala, basal ganglia (BG), and superior colliculus (SC). PMID:24987339

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

Yan, Rui; Praggastis, Brenda L.; Smith, William P.

While streaming data have become increasingly more popular in business and research communities, semantic models and processing software for streaming data have not kept pace. Traditional semantic solutions have not addressed transient data streams. Semantic web languages (e.g., RDF, OWL) have typically addressed static data settings and linked data approaches have predominantly addressed static or growing data repositories. Streaming data settings have some fundamental differences; in particular, data are consumed on the fly and data may expire. Stream reasoning, a combination of stream processing and semantic reasoning, has emerged with the vision of providing "smart" processing of streaming data. C-SPARQLmore » is a prominent stream reasoning system that handles semantic (RDF) data streams. Many stream reasoning systems including C-SPARQL use a sliding window and use data arrival time to evict data. For data streams that include expiration times, a simple arrival time scheme is inadequate if the window size does not match the expiration period. In this paper, we propose a cache-enabled, order-aware, ontology-based stream reasoning framework. This framework consumes RDF streams with expiration timestamps assigned by the streaming source. Our framework utilizes both arrival and expiration timestamps in its cache eviction policies. In addition, we introduce the notion of "semantic importance" which aims to address the relevance of data to the expected reasoning, thus enabling the eviction algorithms to be more context- and reasoning-aware when choosing what data to maintain for question answering. We evaluate this framework by implementing three different prototypes and utilizing five metrics. The trade-offs of deploying the proposed framework are also discussed.« less

Distinct and overlapping fMRI activation networks for processing of novel identities and locations of objects.

PubMed

Pihlajamäki, Maija; Tanila, Heikki; Könönen, Mervi; Hänninen, Tuomo; Aronen, Hannu J; Soininen, Hilkka

2005-10-01

The ventral visual stream processes information about the identity of objects ('what'), whereas the dorsal stream processes the spatial locations of objects ('where'). There is a corresponding, although disputed, distinction for the ventrolateral and dorsolateral prefrontal areas. Furthermore, there seems to be a distinction between the anterior and posterior medial temporal lobe (MTL) structures in the processing of novel items and new spatial arrangements, respectively. Functional differentiation of the intermediary mid-line cortical and temporal neocortical structures that communicate with the occipitotemporal, occipitoparietal, prefrontal, and MTL structures, however, is unclear. Therefore, in the present functional magnetic resonance imaging (fMRI) study, we examined whether the distinction among the MTL structures extends to these closely connected cortical areas. The most striking difference in the fMRI responses during visual presentation of changes in either items or their locations was the bilateral activation of the temporal lobe and ventrolateral prefrontal cortical areas for novel object identification in contrast to wide parietal and dorsolateral prefrontal activation for the novel locations of objects. An anterior-posterior distinction of fMRI responses similar to the MTL was observed in the cingulate/retrosplenial, and superior and middle temporal cortices. In addition to the distinct areas of activation, certain frontal, parietal, and temporo-occipital areas responded to both object and spatial novelty, suggesting a common attentional network for both types of changes in the visual environment. These findings offer new insights to the functional roles and intrinsic specialization of the cingulate/retrosplenial, and lateral temporal cortical areas in visuospatial cognition.

Beyond cool: adapting upland streams for climate change using riparian woodlands.

PubMed

Thomas, Stephen M; Griffiths, Siân W; Ormerod, Steve J

2016-01-01

Managed adaptation could reduce the risks of climate change to the world's ecosystems, but there have been surprisingly few practical evaluations of the options available. For example, riparian woodland is advocated widely as shade to reduce warming in temperate streams, but few studies have considered collateral effects on species composition or ecosystem functions. Here, we use cross-sectional analyses at two scales (region and within streams) to investigate whether four types of riparian management, including those proposed to reduce potential climate change impacts, might also affect the composition, functional character, dynamics and energetic resourcing of macroinvertebrates in upland Welsh streams (UK). Riparian land use across the region had only small effects on invertebrate taxonomic composition, while stable isotope data showed how energetic resources assimilated by macroinvertebrates in all functional guilds were split roughly 50:50 between terrestrial and aquatic origins irrespective of riparian management. Nevertheless, streams draining the most extensive deciduous woodland had the greatest stocks of coarse particulate matter (CPOM) and greater numbers of 'shredding' detritivores. Stream-scale investigations showed that macroinvertebrate biomass in deciduous woodland streams was around twice that in moorland streams, and lowest of all in streams draining non-native conifers. The unexpected absence of contrasting terrestrial signals in the isotopic data implies that factors other than local land use affect the relative incorporation of allochthonous subsidies into riverine food webs. Nevertheless, our results reveal how planting deciduous riparian trees along temperate headwaters as an adaptation to climate change can modify macroinvertebrate function, increase biomass and potentially enhance resilience by increasing basal resources where cover is extensive (>60 m riparian width). We advocate greater urgency in efforts to understand the ecosystem consequences of climate change adaptation to guide future actions. © 2015 John Wiley & Sons Ltd.

The Role of Riparian Vegetation in Protecting and Improving Chemical Water Quality in Streams

Treesearch

Michael G. Dosskey; Philippe Vidon; Noel P. Gurwick; Craig J. Allan; Tim P. Duval; Richard Lowrance

2010-01-01

We review the research literature and summarize the major processes by which riparian vegetation influences chemical water quality in streams, as well as how these processes vary among vegetation types, and discuss how these processes respond to removal and restoration of riparian vegetation and thereby determine the timing and level of response in stream water quality...

New metrics for evaluating channel networks extracted in grid digital elevation models

NASA Astrophysics Data System (ADS)

Orlandini, S.; Moretti, G.

2017-12-01

Channel networks are critical components of drainage basins and delta regions. Despite the important role played by these systems in hydrology and geomorphology, there are at present no well-defined methods to evaluate numerically how two complex channel networks are geometrically far apart. The present study introduces new metrics for evaluating numerically channel networks extracted in grid digital elevation models with respect to a reference channel network (see the figure below). Streams of the evaluated network (EN) are delineated as in the Horton ordering system and examined through a priority climbing algorithm based on the triple index (ID1,ID2,ID3), where ID1 is a stream identifier that increases as the elevation of lower end of the stream increases, ID2 indicates the ID1 of the draining stream, and ID3 is the ID1 of the corresponding stream in the reference network (RN). Streams of the RN are identified by the double index (ID1,ID2). Streams of the EN are processed in the order of increasing ID1 (plots a-l in the figure below). For each processed stream of the EN, the closest stream of the RN is sought by considering all the streams of the RN sharing the same ID2. This ID2 in the RN is equal in the EN to the ID3 of the stream draining the processed stream, the one having ID1 equal to the ID2 of the processed stream. The mean stream planar distance (MSPD) and the mean stream elevation drop (MSED) are computed as the mean distance and drop, respectively, between corresponding streams. The MSPD is shown to be useful for evaluating slope direction methods and thresholds for channel initiation, whereas the MSED is shown to indicate the ability of grid coarsening strategies to retain the profiles of observed channels. The developed metrics fill a gap in the existing literature by allowing hydrologists and geomorphologists to compare descriptions of a fixed physical system obtained by using different terrain analysis methods, or different physical systems described by using the same methods.

VPipe: Virtual Pipelining for Scheduling of DAG Stream Query Plans

NASA Astrophysics Data System (ADS)

Wang, Song; Gupta, Chetan; Mehta, Abhay

There are data streams all around us that can be harnessed for tremendous business and personal advantage. For an enterprise-level stream processing system such as CHAOS [1] (Continuous, Heterogeneous Analytic Over Streams), handling of complex query plans with resource constraints is challenging. While several scheduling strategies exist for stream processing, efficient scheduling of complex DAG query plans is still largely unsolved. In this paper, we propose a novel execution scheme for scheduling complex directed acyclic graph (DAG) query plans with meta-data enriched stream tuples. Our solution, called Virtual Pipelined Chain (or VPipe Chain for short), effectively extends the "Chain" pipelining scheduling approach to complex DAG query plans.

Quantifying and Predicting Three-Dimensional Heterogeneity in Transient Storage Using Roving Profiling

NASA Astrophysics Data System (ADS)

Kaplan, D. A.; Reaver, N.; Hensley, R. T.; Cohen, M. J.

2017-12-01

Hydraulic transport is an important component of nutrient spiraling in streams. Quantifying conservative solute transport is a prerequisite for understanding the cycling and fate of reactive solutes, such as nutrients. Numerous studies have modeled solute transport within streams using the one-dimensional advection, dispersion and storage (ADS) equation calibrated to experimental data from tracer experiments. However, there are limitations to the information about in-stream transient storage that can be derived from calibrated ADS model parameters. Transient storage (TS) in the ADS model is most often modeled as a single process, and calibrated model parameters are "lumped" values that are the best-fit representation of multiple real-world TS processes. In this study, we developed a roving profiling method to assess and predict spatial heterogeneity of in-stream TS. We performed five tracer experiments on three spring-fed rivers in Florida (USA) using Rhodamine WT. During each tracer release, stationary fluorometers were deployed to measure breakthrough curves for multiple reaches within the river. Teams of roving samplers moved along the rivers measuring tracer concentrations at various locations and depths within the reaches. A Bayesian statistical method was used to calibrate the ADS model to the stationary breakthrough curves, resulting in probability distributions for both the advective and TS zone as a function of river distance and time. Rover samples were then assigned a probability of being from either the advective or TS zone by comparing measured concentrations to the probability distributions of concentrations in the ADS advective and TS zones. A regression model was used to predict the probability of any in-stream position being located within the advective versus TS zone based on spatiotemporal predictors (time, river position, depth, and distance from bank) and eco-geomorphological feature (eddies, woody debris, benthic depressions, and aquatic vegetation). Results confirm that TS is spatially variable as a function of spatiotemporal and eco-geomorphological features. A substantial number of samples with nearly equivalent chances of being from the advective or TS zones suggests that the distinction between zones is often poorly defined.

Exploiting the MODIS albedos with the Two-stream Inversion Package (JRC-TIP): 2. Fractions of transmitted and absorbed fluxes in the vegetation and soil layers

NASA Astrophysics Data System (ADS)

Pinty, B.; Clerici, M.; Andredakis, I.; Kaminski, T.; Taberner, M.; Verstraete, M. M.; Gobron, N.; Plummer, S.; Widlowski, J.-L.

2011-05-01

The two-stream model parameters and associated uncertainties retrieved by inversion against MODIS broadband visible and near-infrared white sky surface albedos were discussed in a companion paper. The present paper concentrates on the partitioning of the solar radiation fluxes delivered by the Joint Research Centre Two-stream Inversion Package (JRC-TIP). The estimation of the various flux fractions related to the vegetation and the background layers separately capitalizes on the probability density functions of the model parameters discussed in the companion paper. The propagation of uncertainties from the observations to the model parameters is achieved via the Hessian of the cost function and yields a covariance matrix of posterior parameter uncertainties. This matrix is propagated to the radiation fluxes via the model's Jacobian matrix of first derivatives. Results exhibit a rather good spatiotemporal consistency given that the prior values on the model parameters are not specified as a function of land cover type and/or vegetation phenological states. A specific investigation based on a scenario imposing stringent conditions of leaf absorbing and scattering properties highlights the impact of such constraints that are, as a matter of fact, currently adopted in vegetation index approaches. Special attention is also given to snow-covered and snow-contaminated areas since these regions encompass significant reflectance changes that strongly affect land surface processes. A definite asset of the JRC-TIP lies in its capability to control and ultimately relax a number of assumptions that are often implicit in traditional approaches. These features greatly help us understand the discrepancies between the different data sets of land surface properties and fluxes that are currently available. Through a series of selected examples, the inverse procedure implemented in the JRC-TIP is shown to be robust, reliable, and compliant with large-scale processing requirements. Furthermore, this package ensures the physical consistency between the set of observations, the two-stream model parameters, and radiation fluxes. It also documents the retrieval of associated uncertainties.

Foundations for Streaming Model Transformations by Complex Event Processing.

PubMed

Dávid, István; Ráth, István; Varró, Dániel

2018-01-01

Streaming model transformations represent a novel class of transformations to manipulate models whose elements are continuously produced or modified in high volume and with rapid rate of change. Executing streaming transformations requires efficient techniques to recognize activated transformation rules over a live model and a potentially infinite stream of events. In this paper, we propose foundations of streaming model transformations by innovatively integrating incremental model query, complex event processing (CEP) and reactive (event-driven) transformation techniques. Complex event processing allows to identify relevant patterns and sequences of events over an event stream. Our approach enables event streams to include model change events which are automatically and continuously populated by incremental model queries. Furthermore, a reactive rule engine carries out transformations on identified complex event patterns. We provide an integrated domain-specific language with precise semantics for capturing complex event patterns and streaming transformations together with an execution engine, all of which is now part of the Viatra reactive transformation framework. We demonstrate the feasibility of our approach with two case studies: one in an advanced model engineering workflow; and one in the context of on-the-fly gesture recognition.

A Stream Morphology Classification for Eco-hydraulic Purposes Based on Geospatial Data: a Solute Transport Application Case

NASA Astrophysics Data System (ADS)

Jiménez Jaramillo, M. A.; Camacho Botero, L. A.; Vélez Upegui, J. I.

2010-12-01

Variation in stream morphology along a basin drainage network leads to different hydraulic patterns and sediment transport processes. Moreover, solute transport processes along streams, and stream habitats for fisheries and microorganisms, rely on stream corridor structure, including elements such as bed forms, channel patterns, riparian vegetation, and the floodplain. In this work solute transport processes simulation and stream habitat identification are carried out at the basin scale. A reach-scale morphological classification system based on channel slope and specific stream power was implemented by using digital elevation models and hydraulic geometry relationships. Although the morphological framework allows identification of cascade, step-pool, plane bed and pool-riffle morphologies along the drainage network, it still does not account for floodplain configuration and bed-forms identification of those channel types. Hence, as a first application case in order to obtain parsimonious three-dimensional characterizations of drainage channels, the morphological framework has been updated by including topographical floodplain delimitation through a Multi-resolution Valley Bottom Flatness Index assessing, and a stochastic bed form representation of the step-pool morphology. Model outcomes were tested in relation to in-stream water storage for different flow conditions and representative travel times according to the Aggregated Dead Zone -ADZ- model conceptualization of solute transport processes.

Recovery of a tropical stream after a harvest-related chlorine poisoning event.

Treesearch

EFFIE A. GREATHOUSE; JAMES G. MARCH; PRINGLE; CATHERINE M.

2005-01-01

1. Harvest-related poisoning events are common in tropical streams, yet research on stream recovery has largely been limited to temperate streams and generally does not include any measures of ecosystem function, such as leaf breakdown. 2. We assessed recovery of a second-order, high-gradient stream draining the Luquillo Experimental Forest, Puerto Rico, 3 months after...

AN INDICATOR OF POTENTIAL STREAM WOOD CONTRIBUTION FOR RIPARIAN FORESTS

EPA Science Inventory

In northwestern Oregon a key function of riparian forests is to provide wood to the stream network. This function is a prominent feature of Federal and State forest practices in the region. Thus, defining indicators which are associated with this function are important for desi...

Sewage treatment method

DOEpatents

Fassbender, Alex G.

1995-01-01

The invention greatly reduces the amount of ammonia in sewage plant effluent. The process of the invention has three main steps. The first step is dewatering without first digesting, thereby producing a first ammonia-containing stream having a low concentration of ammonia, and a second solids-containing stream. The second step is sending the second solids-containing stream through a means for separating the solids from the liquid and producing an aqueous stream containing a high concentration of ammonia. The third step is removal of ammonia from the aqueous stream using a hydrothermal process.

Optical fiber repeatered transmission systems utilizing SAW filters

NASA Astrophysics Data System (ADS)

Rosenberg, R. L.; Ross, D. G.; Trischitta, P. R.; Fishman, D. A.; Armitage, C. B.

1983-05-01

Baseband digital transmission-line systems capable of signaling rates of several hundred to several thousand Mbit/s are presently being developed around the world. The pulse regeneration process is gated by a timing wave which is synchronous with the symbol rate of the arriving pulse stream. Synchronization is achieved by extracting a timing wave from the arriving pulse stream, itself. To date, surface acoustic-wave (SAW) filters have been widely adopted for timing recovery in the in-line regenerators of high-bit-rate systems. The present investigation has the objective to acquaint the SAW community in general, and SAW filter suppliers in particular, with the requirements for timing recovery filters in repeatered digital transmission systems. Attention is given to the system structure, the timing loop function, the system requirements affecting the timing-recovery filter, the decision process, timing jitter accumulation, the filter 'ringing' requirement, and aspects of reliability.

The Solar Wind and Geomagnetic Activity as a Function of Time Relative to Corotating Interaction Regions

NASA Technical Reports Server (NTRS)

McPherron, Robert L.; Weygand, James

2006-01-01

Corotating interaction regions during the declining phase of the solar cycle are the cause of recurrent geomagnetic storms and are responsible for the generation of high fluxes of relativistic electrons. These regions are produced by the collision of a high-speed stream of solar wind with a slow-speed stream. The interface between the two streams is easily identified with plasma and field data from a solar wind monitor upstream of the Earth. The properties of the solar wind and interplanetary magnetic field are systematic functions of time relative to the stream interface. Consequently the coupling of the solar wind to the Earth's magnetosphere produces a predictable sequence of events. Because the streams persist for many solar rotations it should be possible to use terrestrial observations of past magnetic activity to predict future activity. Also the high-speed streams are produced by large unipolar magnetic regions on the Sun so that empirical models can be used to predict the velocity profile of a stream expected at the Earth. In either case knowledge of the statistical properties of the solar wind and geomagnetic activity as a function of time relative to a stream interface provides the basis for medium term forecasting of geomagnetic activity. In this report we use lists of stream interfaces identified in solar wind data during the years 1995 and 2004 to develop probability distribution functions for a variety of different variables as a function of time relative to the interface. The results are presented as temporal profiles of the quartiles of the cumulative probability distributions of these variables. We demonstrate that the storms produced by these interaction regions are generally very weak. Despite this the fluxes of relativistic electrons produced during those storms are the highest seen in the solar cycle. We attribute this to the specific sequence of events produced by the organization of the solar wind relative to the stream interfaces. We also show that there are large quantitative differences in various parameters between the two cycles.

Discontinuities in stream nutrient uptake below lakes in mountain drainage networks

USGS Publications Warehouse

Arp, C.D.; Baker, M.A.

2007-01-01

In many watersheds, lakes and streams are hydrologically linked in spatial patterns that influence material transport and retention. We hypothesized that lakes affect stream nutrient cycling via modifications to stream hydrogeomorphology, source-waters, and biological communities. We tested this hypothesis in a lake district of the Sawtooth Mountains, Idaho. Uptake of NO3- and PO4-3 was compared among 25 reaches representing the following landscape positions: lake inlets and outlets, reaches >1-km downstream from lakes, and reference reaches with no nearby lakes. We quantified landscape-scale hydrographic and reach-scale hydrogeomorphic, source-water, and biological variables to characterize these landscape positions and analyze relationships to nutrient uptake. Nitrate uptake was undetectable at most lake outlets, whereas PO4-3 uptake was higher at outlets as compared to reference and lake inlet reaches. Patterns in nutrient demand farther downstream were similar to lake outlets with a gradual shift toward reference-reach functionality. Nitrate uptake was most correlated to sediment mobility and channel morphology, whereas PO 4-3 uptake was most correlated to source-water characteristics. The best integrated predictor of these patterns in nutrient demand was % contributing area (the proportion of watershed area not routing through a lake). We estimate that NO3- and PO 4-3 demand returned to 50% of pre-lake conditions within 1-4-km downstream of a small headwater lake and resetting of nutrient demand was slower downstream of a larger lake set lower in a watershed. Full resetting of these nutrient cycling processes was not reached within 20-km downstream, indicating that lakes can alter stream ecosystem functioning at large spatial scales throughout mountain watersheds. ?? 2007, by the American Society of Limnology and Oceanography, Inc.

Drivers of River Water Temperature Space-time Variability in Northeast Greenland

NASA Astrophysics Data System (ADS)

Hannah, D. M.; Docherty, C.; Milner, A.

2015-12-01

Water temperature plays an important role in stream ecosystem functioning; however, water temperature dynamics in high Arctic environments have received relatively little attention. Given that global climate is predicted to change most at high latitudes, it is vital we broaden our knowledge of space-time variability in Arctic river temperature to understand controlling processes and potential consequences of climate change. To address this gap, our research aims: (1) to characterise seasonal and diel patterns of variability over three summer and two winter seasons with contrasting hydrometeorological conditions, (2) to unravel the key drivers influencing thermal regimes and (3) to place these results in the context of other snow/ glacier-melt dominated environments. Fieldwork was undertaken in July-September 2013, 2014 and 2015 close to the Zackenberg Research Station in Northeast Greenland - an area of continuous permafrost with a mean July air temperature of 6 °C. Five streams were chosen that drain different water source contributions (glacier melt, snow melt, groundwater). Data were collected at 30 minute intervals using micro-dataloggers. Air temperature data were collected within 7km by the Greenland Survey. Weather conditions were highly variable between field campaigns, with 2013 experiencing below average, and 2014 and 2015 above average, snowfall. Summer water temperatures appear to be high in comparison to some Arctic streams in Alaska and in Svalbard. Winter snowfall extent decreases stream water temperature; and water temperature increases with atmospheric exposure time (distance from source) - illustrating the intertwined controls of water and heat fluxes. These Greenland streams are most strongly influenced by snowmelt, but groundwater contributions could increase with a changing climate due to increased active layer thickness, which may result in increased river temperature with implications for aquatic biodiversity and ecosystem functioning.

Time series and recurrence interval models to predict the vulnerability of streams to episodic acidification in Shenandoah National Park, Virginia

USGS Publications Warehouse

Deviney, Frank A.; Rice, Karen C.; Hornberger, George M.

2006-01-01

Acid rain affects headwater streams by temporarily reducing the acid‐neutralizing capacity (ANC) of the water, a process termed episodic acidification. The increase in acidic components in stream water can have deleterious effects on the aquatic biota. Although acidic deposition is uniform across Shenandoah National Park (SNP) in north central Virginia, the stream water quality response during rain events varies substantially. This response is a function of the catchment's underlying geology and topography. Geologic and topographic data for SNP's 231 catchments are readily available; however, long‐term measurements (tens of years) of ANC and accompanying discharge are not and would be prohibitively expensive to collect. Transfer function time series models were developed to predict hourly ANC from discharge for five SNP catchments with long‐term water‐quality and discharge records. Hourly ANC predictions over short time periods (≤1 week) were averaged, and distributions of the recurrence intervals of annual water‐year minimum ANC values were model‐simulated for periods of 6, 24, 72, and 168 hours. The distributions were extrapolated to the rest of the SNP catchments on the basis of catchment geology and topography. On the basis of the models, large numbers of SNP streams have 6‐ to 168‐hour periods of low‐ANC values, which may stress resident fish populations. Smaller catchments are more vulnerable to episodic acidification than larger catchments underlain by the same bedrock. Catchments with similar topography and size are more vulnerable if underlain by less basaltic/carbonate bedrock. Many catchments are predicted to have successive years of low‐ANC values potentially sufficient to extirpate some species.

Macrophyte presence is an indicator of enhanced denitrification and nitrification in sediments of a temperate restored agricultural stream

EPA Science Inventory

Stream macrophytes are often removed with their sediments to deepen stream channels, stabilize channel banks, or provide habitat for target species. These sediments may support enhanced nitrogen processing. To evaluate sediment nitrogen processing, identify seasonal patterns, and...

Serial and Parallel Processing in the Primate Auditory Cortex Revisited

PubMed Central

Recanzone, Gregg H.; Cohen, Yale E.

2009-01-01

Over a decade ago it was proposed that the primate auditory cortex is organized in a serial and parallel manner in which there is a dorsal stream processing spatial information and a ventral stream processing non-spatial information. This organization is similar to the “what”/“where” processing of the primate visual cortex. This review will examine several key studies, primarily electrophysiological, that have tested this hypothesis. We also review several human imaging studies that have attempted to define these processing streams in the human auditory cortex. While there is good evidence that spatial information is processed along a particular series of cortical areas, the support for a non-spatial processing stream is not as strong. Why this should be the case and how to better test this hypothesis is also discussed. PMID:19686779

Modelling Stream-Fish Functional Traits in Reference Conditions: Regional and Local Environmental Correlates

PubMed Central

Oliveira, João M.; Segurado, Pedro; Santos, José M.; Teixeira, Amílcar; Ferreira, Maria T.; Cortes, Rui V.

2012-01-01

Identifying the environmental gradients that control the functional structure of biological assemblages in reference conditions is fundamental to help river management and predict the consequences of anthropogenic stressors. Fish metrics (density of ecological guilds, and species richness) from 117 least disturbed stream reaches in several western Iberia river basins were modelled with generalized linear models in order to investigate the importance of regional- and local-scale abiotic gradients to variation in functional structure of fish assemblages. Functional patterns were primarily associated with regional features, such as catchment elevation and slope, rainfall, and drainage area. Spatial variations of fish guilds were thus associated with broad geographic gradients, showing (1) pronounced latitudinal patterns, affected mainly by climatic factors and topography, or (2) at the basin level, strong upstream-downstream patterns related to stream position in the longitudinal gradient. Maximum native species richness was observed in midsize streams in accordance with the river continuum concept. The findings of our study emphasized the need to use a multi-scale approach in order to fully assess the factors that govern the functional organization of biotic assemblages in ‘natural’ streams, as well as to improve biomonitoring and restoration of fluvial ecosystems. PMID:23029242

Are macroinvertebrate functional traits useful in differentiating hydrologically variable small piedmont streams and their recovery from drought?

EPA Science Inventory

We quantified benthic macroinvertebrates in six small (1st order) Alabama piedmont streams from 1994-1998. Streams spanned a gradient of hydrologic permanence from typically intermittent to perennial, the degree of permanence for a given stream depending on water year. Initial sa...

Effects of urban stream burial on nitrogen uptake and ecosystem metabolism: implications for watershed nitrogen and carbon fluxes

EPA Science Inventory

Urbanization has resulted in extensive burial and channelization of headwater streams, yet little is known about impacts on stream ecosystem functions critical for reducing downstream nitrogen pollution. To characterize the biogeochemical impact of stream burial, we measured NO3...

Experimental whole-stream warming alters community size structure.

PubMed

Nelson, Daniel; Benstead, Jonathan P; Huryn, Alexander D; Cross, Wyatt F; Hood, James M; Johnson, Philip W; Junker, James R; Gíslason, Gísli M; Ólafsson, Jón S

2017-07-01

How ecological communities respond to predicted increases in temperature will determine the extent to which Earth's biodiversity and ecosystem functioning can be maintained into a warmer future. Warming is predicted to alter the structure of natural communities, but robust tests of such predictions require appropriate large-scale manipulations of intact, natural habitat that is open to dispersal processes via exchange with regional species pools. Here, we report results of a two-year whole-stream warming experiment that shifted invertebrate assemblage structure via unanticipated mechanisms, while still conforming to community-level metabolic theory. While warming by 3.8 °C decreased invertebrate abundance in the experimental stream by 60% relative to a reference stream, total invertebrate biomass was unchanged. Associated shifts in invertebrate assemblage structure were driven by the arrival of new taxa and a higher proportion of large, warm-adapted species (i.e., snails and predatory dipterans) relative to small-bodied, cold-adapted taxa (e.g., chironomids and oligochaetes). Experimental warming consequently shifted assemblage size spectra in ways that were unexpected, but consistent with thermal optima of taxa in the regional species pool. Higher temperatures increased community-level energy demand, which was presumably satisfied by higher primary production after warming. Our experiment demonstrates how warming reassembles communities within the constraints of energy supply via regional exchange of species that differ in thermal physiological traits. Similar responses will likely mediate impacts of anthropogenic warming on biodiversity and ecosystem function across all ecological communities. © 2016 John Wiley & Sons Ltd.

Use of StreamStats in the Upper French Broad River Basin, North Carolina: A Pilot Water-Resources Web Application

USGS Publications Warehouse

Wagner, Chad R.; Tighe, Kirsten C.; Terziotti, Silvia

2009-01-01

StreamStats is a Web-based Geographic Information System (GIS) application that was developed by the U.S. Geological Survey (USGS) in cooperation with Environmental Systems Research Institute, Inc. (ESRI) to provide access to an assortment of analytical tools that are useful for water-resources planning and management. StreamStats allows users to easily obtain streamflow statistics, basin characteristics, and descriptive information for USGS data-collection sites and selected ungaged sites. StreamStats also allows users to identify stream reaches upstream and downstream from user-selected sites and obtain information for locations along streams where activities occur that can affect streamflow conditions. This functionality can be accessed through a map-based interface with the user's Web browser or through individual functions requested remotely through other Web applications.

Water ecosystem service function assessment based on eco-hydrological process in Luanhe Basin,China

NASA Astrophysics Data System (ADS)

Zhang, C.; Hao, C.; Qin, T.; Wang, G.; Weng, B.

2012-12-01

At present, ecological water are mainly occupied by a rapid development of social economic and population explosion, which seriously threat the ecological security and water security in watershed and regional scale. Due to the lack of a unified standard of measuring the benefit of water resource, social economic and ecosystem, the water allocation can't take place in social economic and ecosystem. The function which provided by water in terrestrial, aquatic and social economic system can be addressed through water ecosystem service function research, and it can guide the water allocation in water resource management. The function which provided by water in terrestrial, aquatic and social economic system can be addressed through water ecosystem service function research, and it can guide the water allocation in water resource management. Throughout the researches of water ecosystem service, a clear identification of the connection of water ecosystem service function has not been established, and eco-economic approach can't meet the practical requirement of water allocation. Based on "nature-artificiality" dual water cycle theory and eco-hydrological process, this paper proposes a connection and indicator system of water ecosystem service function. In approach, this paper establishes an integrated assessment approach through prototype observation technology, numerical simulation, physical simulation and modern geographic information technology. The core content is to couple an eco-hydrological model, which involves the key processes of distributed hydrological model (WEP), ecological model (CLM-DGVM), in terms of eco-hydrological process. This paper systematically evaluates the eco-hydrological process and evolution of Luanhe Basin in terms of precipitation, ET, runoff, groundwater, ecosystem's scale, form and distribution. According to the results of eco-hydrological process, this paper assesses the direct and derived service function. The result indicates that the general service function of 2010 has minor increase than 2007, however the general function of two years are in common level; Compare with different region, the upstream, middle stream and downstream indicates "worse", "common" and "good" level respectively. The first three derived functions are leisure, offer products and industrial water use. In the end, this paper investigates the evolution of water ecosystem service function under rising temperatures and elevated CO2 concentration scenarios in Luanhe Basin through eco-hydrological model. The results elaborate that the water ecosystem service functions would decline when temperature rising, and warming to 1.5 degree is the mutation point of sharp drop; Increased CO2 concentration scenario will improve the direct service function in the whole Basin; under the overlying scenario, different region shows different results, the direct service function will increased in upstream and middle stream, direct service function will drop in downstream. A comprehensive analysis indicates that the rising temperature is the major driven of water ecosystem service function in Luanhe Basin.

EFFECTS OF HYDROLOGY ON NITROGEN PROCESSING IN A RESTORED URBAN STREAM

EPA Science Inventory

In 2001, EPA undertook an intensive research effort to evaluate the impact of stream restoration on water quality at a degraded stream in an urban watershed. An essential piece of this comprehensive study was to characterize, measure and quantify stream ground water/ stream wate...

40 CFR 63.146 - Process wastewater provisions-reporting.

Code of Federal Regulations, 2014 CFR

2014-07-01

... wastewater provisions—reporting. (a) For each waste management unit, treatment process, or control device... for Group 2 wastewater streams. This paragraph does not apply to Group 2 wastewater streams that are used to comply with § 63.138(g). For Group 2 wastewater streams, the owner or operator shall include...

40 CFR 63.146 - Process wastewater provisions-reporting.

Code of Federal Regulations, 2012 CFR

2012-07-01

... wastewater provisions—reporting. (a) For each waste management unit, treatment process, or control device... for Group 2 wastewater streams. This paragraph does not apply to Group 2 wastewater streams that are used to comply with § 63.138(g). For Group 2 wastewater streams, the owner or operator shall include...

40 CFR 63.146 - Process wastewater provisions-reporting.

Code of Federal Regulations, 2011 CFR

2011-07-01

... wastewater provisions—reporting. (a) For each waste management unit, treatment process, or control device... for Group 2 wastewater streams. This paragraph does not apply to Group 2 wastewater streams that are used to comply with § 63.138(g). For Group 2 wastewater streams, the owner or operator shall include...

40 CFR 63.146 - Process wastewater provisions-reporting.

Code of Federal Regulations, 2013 CFR

2013-07-01

... wastewater provisions—reporting. (a) For each waste management unit, treatment process, or control device... for Group 2 wastewater streams. This paragraph does not apply to Group 2 wastewater streams that are used to comply with § 63.138(g). For Group 2 wastewater streams, the owner or operator shall include...

Temporal variation of meandering intensity and domain-wide lateral oscillations of the Gulf Stream

NASA Technical Reports Server (NTRS)

Lee, Tong; Cornillon, Peter

1995-01-01

The path of the Gulf Stream exhibits two modes of variability: wavelike spatial meanders associated with instability processes and large-sale lateral shifts of the path presumably due to atmospheric forcing. The objectives of this study are to examine the temporal variation of the intensity of spatial meandering in the stream, to characterize large-scale lateral oscillations in the stream's path, and to study the correlation betwen these two dynamically distinct modes of variability. The data used for this analysis are path displacemets ofthe Gulf Stream between 75 deg and 60 deg W obtained from AVHRR-derived (Advanced Very High Resolution Radiometer) infrared images for the period April 1982 through December 1989. Meandering intensity, measured by the spatial root-mean-sqaure displacement of the stream path, displays a 9-month dominant periodicity which is persistent through the study period. The 9-month fluctuation in meandering intensity may be related to the interaction of Rosseby waves with the stream. Interannual variation of meandering intensity is also found to be significant, with meandering being mich more intense during 1985 than it was in 1987. Annual variation, however,is weak and not well-defined.The spatially averaged position of the stream, which reflects nonmeandering large-scale lateral oscillations of the stream path, is dominated by an annual cycle. On average, the mean position is farthest north in November and farthest south in April. The first empirical orthogonal function mode of the space-time path displacements represents lateral oscillatins that are in-phase over the space-time domain. Interannual oscillations are also observed and are found to be weaker than the annual oscillation. The eigenvalue of the first mode indicates that about 21.5% of the total space-time variability of the stream path can be attibuted to domain-wide lateral oscillation. The correlation between meandering intensity and domain-wide lateral oscillations is very weak.

A method to assess longitudinal riverine connectivity in tropical streams dominated by migratory biota

USGS Publications Warehouse

Crook, K.E.; Pringle, C.M.; Freeman, Mary C.

2009-01-01

1. One way in which dams affect ecosystem function is by altering the distribution and abundance of aquatic species. 2. Previous studies indicate that migratory shrimps have significant effects on ecosystem processes in Puerto Rican streams, but are vulnerable to impediments to upstream or downstream passage, such as dams and associated water intakes where stream water is withdrawn for human water supplies. Ecological effects of dams and water withdrawals from streams depend on spatial context and temporal variability of flow in relation to the amount of water withdrawn. 3. This paper presents a conceptual model for estimating the probability that an individual shrimp is able to migrate from a stream's headwaters to the estuary as a larva, and then return to the headwaters as a juvenile, given a set of dams and water withdrawals in the stream network. The model is applied to flow and withdrawal data for a set of dams and water withdrawals in the Caribbean National Forest (CNF) in Puerto Rico. 4. The index of longitudinal riverine connectivity (ILRC), is used to classify 17 water intakes in streams draining the CNF as having low, moderate, or high connectivity in terms of shrimp migration in both directions. An in-depth comparison of two streams showed that the stream characterized by higher water withdrawal had low connectivity, even during wet periods. Severity of effects is illustrated by a drought year, where the most downstream intake caused 100% larval shrimp mortality 78% of the year. 5. The ranking system provided by the index can be used as a tool for conservation ecologists and water resource managers to evaluate the relative vulnerability of migratory biota in streams, across different scales (reach-network), to seasonally low flows and extended drought. This information can be used to help evaluate the environmental tradeoffs of future water withdrawals. ?? 2008 John Wiley & Sons, Ltd.

Are Longitudinal Patterns of Bacterial Community Composition and Dissolved Organic Matter Composition Linked Across a River Continuum? (Invited)

NASA Astrophysics Data System (ADS)

Mosher, J.; Kaplan, L. A.; Kan, J.; Findlay, R. H.; Podgorski, D. C.; McKenna, A. M.; Branan, T. L.; Griffith, C.

2013-12-01

The River Continuum Concept (RCC), an early meta-ecosystem idea, was developed without the benefit of new frontiers in molecular microbial ecology and ultra-high resolution mass spectrometry. We have applied technical advances in these areas to address a hypothesis implicit in the RCC that the upstream legacy of DOM processing contributes to the structure and function of downstream bacterial communities. DOM molecular structure and microbial community structure were measured across river networks within three distinct forested catchments. High-throughput pyrosequencing of bacterial 16S rRNA amplicons and phospholipid fatty acid analysis were used to characterize bacterial communities, and ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry characterized the molecular composition of stream water DOM. Total microbial biomass varied among river networks but showed a trend of decreasing biomass in sediment with increasing stream order. There were distinct shifts in bacterial community structure and a trend of decreasing richness was observed traveling downstream in both sediment and epilithic habitats. The bacterial richness in the first order stream sediment habitats was 7728 genera which decreased to 6597 genera in the second order sites and 4867 genera in the third order streams. The richness in the epilithic biofilm habitats was 2830 genera in the first order, 2322 genera in the second order and 1629 genera in the third order sites. Over 45% of the sediment biofilm genera and 37% of the epilithic genera were found in all three orders. In addition to shifts in bacterial richness, we observed a longitudinal shift in bacterial functional-types. In the sediment biofilms, Rhodoplanes spp. (containing rhodopsin pigment) and Bradyrhizobium spp. (nitrogen fixing bacteria) were predominately found in the heavily forested first order streams, while the cyanobacteria Limnothrix spp. was dominant in the second order streams. The third order streams had higher abundances of Sphingomonadaceae spp. and Nordella spp. (both Alphaproteobacteria). The cyanobacteria Chamaesiphon spp. was observed in highest abundance in the first and second order streams of the rock biofilm samples and the cyanobacteria Oscillatoria spp. was in highest abundance in the third order streams. Stream water samples from all orders had high lignin/tannin content and were enriched with carboxylic-rich alicyclic molecules (CRAM). There was an observable shift in in the molecular weight and relative abundance of the CRAM molecules with the CRAM molecules becoming less abundant and having lower molecular weight following the downstream gradient. Multivariate statistical analyses correlated the longitudinal patterns of changes in bacterial community structure to the DOM molecular structure and geochemical parameters across the river continuum.

Controlled temperature expansion in oxygen production by molten alkali metal salts

DOEpatents

Erickson, Donald C.

1985-06-04

A continuous process is set forth for the production of oxygen from an oxygen containing gas stream, such as air, by contacting a feed gas stream with a molten solution of an oxygen acceptor to oxidize the acceptor and cyclically regenerating the oxidized acceptor by releasing oxygen from the acceptor wherein the oxygen-depleted gas stream from the contact zone is treated sequentially to temperature reduction by heat exchange against the feed stream so as to condense out entrained oxygen acceptor for recycle to the process, combustion of the gas stream with fuel to elevate its temperature and expansion of the combusted high temperature gas stream in a turbine to recover power.

Controlled temperature expansion in oxygen production by molten alkali metal salts

DOEpatents

Erickson, D.C.

1985-06-04

A continuous process is set forth for the production of oxygen from an oxygen containing gas stream, such as air, by contacting a feed gas stream with a molten solution of an oxygen acceptor to oxidize the acceptor and cyclically regenerating the oxidized acceptor by releasing oxygen from the acceptor wherein the oxygen-depleted gas stream from the contact zone is treated sequentially to temperature reduction by heat exchange against the feed stream so as to condense out entrained oxygen acceptor for recycle to the process, combustion of the gas stream with fuel to elevate its temperature and expansion of the combusted high temperature gas stream in a turbine to recover power. 1 fig.

Methanation of gas streams containing carbon monoxide and hydrogen

DOEpatents

Frost, Albert C.

1983-01-01

Carbon monoxide-containing gas streams having a relatively high concentration of hydrogen are pretreated so as to remove the hydrogen in a recoverable form for use in the second step of a cyclic, essentially two-step process for the production of methane. The thus-treated streams are then passed over a catalyst to deposit a surface layer of active surface carbon thereon essentially without the formation of inactive coke. This active carbon is reacted with said hydrogen removed from the feed gas stream to form methane. The utilization of the CO in the feed gas stream is appreciably increased, enhancing the overall process for the production of relatively pure, low-cost methane from CO-containing waste gas streams.

Method for removing undesired particles from gas streams

DOEpatents

Durham, M.D.; Schlager, R.J.; Ebner, T.G.; Stewart, R.M.; Hyatt, D.E.; Bustard, C.J.; Sjostrom, S.

1998-11-10

The present invention discloses a process for removing undesired particles from a gas stream including the steps of contacting a composition containing an adhesive with the gas stream; collecting the undesired particles and adhesive on a collection surface to form an aggregate comprising the adhesive and undesired particles on the collection surface; and removing the agglomerate from the collection zone. The composition may then be atomized and injected into the gas stream. The composition may include a liquid that vaporizes in the gas stream. After the liquid vaporizes, adhesive particles are entrained in the gas stream. The process may be applied to electrostatic precipitators and filtration systems to improve undesired particle collection efficiency. 11 figs.

Method and apparatus for decreased undesired particle emissions in gas streams

DOEpatents

Durham, M.D.; Schlager, R.J.; Ebner, T.G.; Stewart, R.M.; Bustard, C.J.

1999-04-13

The present invention discloses a process for removing undesired particles from a gas stream including the steps of contacting a composition containing an adhesive with the gas stream; collecting the undesired particles and adhesive on a collection surface to form an aggregate comprising the adhesive and undesired particles on the collection surface; and removing the agglomerate from the collection zone. The composition may then be atomized and injected into the gas stream. The composition may include a liquid that vaporizes in the gas stream. After the liquid vaporizes, adhesive particles are entrained in the gas stream. The process may be applied to electrostatic precipitators and filtration systems to improve undesired particle collection efficiency. 5 figs.

Method and apparatus for decreased undesired particle emissions in gas streams

DOEpatents

Durham, Michael Dean; Schlager, Richard John; Ebner, Timothy George; Stewart, Robin Michele; Bustard, Cynthia Jean

1999-01-01

The present invention discloses a process for removing undesired particles from a gas stream including the steps of contacting a composition containing an adhesive with the gas stream; collecting the undesired particles and adhesive on a collection surface to form an aggregate comprising the adhesive and undesired particles on the collection surface; and removing the agglomerate from the collection zone. The composition may then be atomized and injected into the gas stream. The composition may include a liquid that vaporizes in the gas stream. After the liquid vaporizes, adhesive particles are entrained in the gas stream. The process may be applied to electrostatic precipitators and filtration systems to improve undesired particle collection efficiency.

Method for removing undesired particles from gas streams

DOEpatents

Durham, Michael Dean; Schlager, Richard John; Ebner, Timothy George; Stewart, Robin Michele; Hyatt, David E.; Bustard, Cynthia Jean; Sjostrom, Sharon

1998-01-01

The present invention discloses a process for removing undesired particles from a gas stream including the steps of contacting a composition containing an adhesive with the gas stream; collecting the undesired particles and adhesive on a collection surface to form an aggregate comprising the adhesive and undesired particles on the collection surface; and removing the agglomerate from the collection zone. The composition may then be atomized and injected into the gas stream. The composition may include a liquid that vaporizes in the gas stream. After the liquid vaporizes, adhesive particles are entrained in the gas stream. The process may be applied to electrostatic precipitators and filtration systems to improve undesired particle collection efficiency.

Process and system for removing impurities from a gas

DOEpatents

Henningsen, Gunnar; Knowlton, Teddy Merrill; Findlay, John George; Schlather, Jerry Neal; Turk, Brian S

2014-04-15

A fluidized reactor system for removing impurities from a gas and an associated process are provided. The system includes a fluidized absorber for contacting a feed gas with a sorbent stream to reduce the impurity content of the feed gas; a fluidized solids regenerator for contacting an impurity loaded sorbent stream with a regeneration gas to reduce the impurity content of the sorbent stream; a first non-mechanical gas seal forming solids transfer device adapted to receive an impurity loaded sorbent stream from the absorber and transport the impurity loaded sorbent stream to the regenerator at a controllable flow rate in response to an aeration gas; and a second non-mechanical gas seal forming solids transfer device adapted to receive a sorbent stream of reduced impurity content from the regenerator and transfer the sorbent stream of reduced impurity content to the absorber without changing the flow rate of the sorbent stream.

Linking freshwater tidal hydrology to carbon cycling in bottomland hardwood wetlands

Treesearch

Carl C. Trettin; Brooke J. Czwartacki; Craig J. Allan; Devendra M. Amatya

2016-01-01

Hydrology is recognized as one of the principal factors regulating soil biogeochemical processes in forested wetlands. However, the consequences of tidally mediated hydrology are seldom considered within forested wetlands that occur along tidal water bodies. These tidal water bodies may be either fresh or brackish, and the tidal streams function as a reservoir to...

Evidence for a regime shift in nitrogen export from a forested watershed

Treesearch

J. R. Webster; Jennifer Knoepp; Wayne Swank; Chelcy Miniat

2016-01-01

In this study, we document a functional regime shift in stream inorganic nitrogen (N) processing indicated by a major change in N export from a forested watershed. Evidence from 36 years of data following experimental clearcut logging at Coweeta Hydrologic Laboratory, NC, suggests that forest disturbance in this area can cause elevation of dissolved inorganic...

Data Streams: An Overview and Scientific Applications

NASA Astrophysics Data System (ADS)

Aggarwal, Charu C.

In recent years, advances in hardware technology have facilitated the ability to collect data continuously. Simple transactions of everyday life such as using a credit card, a phone, or browsing the web lead to automated data storage. Similarly, advances in information technology have lead to large flows of data across IP networks. In many cases, these large volumes of data can be mined for interesting and relevant information in a wide variety of applications. When the volume of the underlying data is very large, it leads to a number of computational and mining challenges: With increasing volume of the data, it is no longer possible to process the data efficiently by using multiple passes. Rather, one can process a data item at most once. This leads to constraints on the implementation of the underlying algorithms. Therefore, stream mining algorithms typically need to be designed so that the algorithms work with one pass of the data. In most cases, there is an inherent temporal component to the stream mining process. This is because the data may evolve over time. This behavior of data streams is referred to as temporal locality. Therefore, a straightforward adaptation of one-pass mining algorithms may not be an effective solution to the task. Stream mining algorithms need to be carefully designed with a clear focus on the evolution of the underlying data. Another important characteristic of data streams is that they are often mined in a distributed fashion. Furthermore, the individual processors may have limited processing and memory. Examples of such cases include sensor networks, in which it may be desirable to perform in-network processing of data stream with limited processing and memory [1, 2]. This chapter will provide an overview of the key challenges in stream mining algorithms which arise from the unique setup in which these problems are encountered. This chapter is organized as follows. In the next section, we will discuss the generic challenges that stream mining poses to a variety of data management and data mining problems. The next section also deals with several issues which arise in the context of data stream management. In Sect. 3, we discuss several mining algorithms on the data stream model. Section 4 discusses various scientific applications of data streams. Section 5 discusses the research directions and conclusions.

Role of submerged vegetation in the retention processes of three plant protection products in flow-through stream mesocosms.

PubMed

Stang, Christoph; Wieczorek, Matthias Valentin; Noss, Christian; Lorke, Andreas; Scherr, Frank; Goerlitz, Gerhard; Schulz, Ralf

2014-07-01

Quantitative information on the processes leading to the retention of plant protection products (PPPs) in surface waters is not available, particularly for flow-through systems. The influence of aquatic vegetation on the hydraulic- and sorption-mediated mitigation processes of three PPPs (triflumuron, pencycuron, and penflufen; logKOW 3.3-4.9) in 45-m slow-flowing stream mesocosms was investigated. Peak reductions were 35-38% in an unvegetated stream mesocosm, 60-62% in a sparsely vegetated stream mesocosm (13% coverage with Elodea nuttallii), and in a similar range of 57-69% in a densely vegetated stream mesocosm (100% coverage). Between 89% and 93% of the measured total peak reductions in the sparsely vegetated stream can be explained by an increase of vegetation-induced dispersion (estimated with the one-dimensional solute transport model OTIS), while 7-11% of the peak reduction can be attributed to sorption processes. However, dispersion contributed only 59-71% of the peak reductions in the densely vegetated stream mesocosm, where 29% to 41% of the total peak reductions can be attributed to sorption processes. In the densely vegetated stream, 8-27% of the applied PPPs, depending on the logKOW values of the compounds, were temporarily retained by macrophytes. Increasing PPP recoveries in the aqueous phase were accompanied by a decrease of PPP concentrations in macrophytes indicating kinetic desorption over time. This is the first study to provide quantitative data on how the interaction of dispersion and sorption, driven by aquatic macrophytes, influences the mitigation of PPP concentrations in flowing vegetated stream systems. Copyright © 2014 Elsevier Ltd. All rights reserved.

Process for the physical segregation of minerals

DOEpatents

Yingling, Jon C.; Ganguli, Rajive

2004-01-06

With highly heterogeneous groups or streams of minerals, physical segregation using online quality measurements is an economically important first stage of the mineral beneficiation process. Segregation enables high quality fractions of the stream to bypass processing, such as cleaning operations, thereby reducing the associated costs and avoiding the yield losses inherent in any downstream separation process. The present invention includes various methods for reliably segregating a mineral stream into at least one fraction meeting desired quality specifications while at the same time maximizing yield of that fraction.

Analytic Strategies of Streaming Data for eHealth.

PubMed

Yoon, Sunmoo

2016-01-01

New analytic strategies for streaming big data from wearable devices and social media are emerging in ehealth. We face challenges to find meaningful patterns from big data because researchers face difficulties to process big volume of streaming data using traditional processing applications.1 This introductory 180 minutes tutorial offers hand-on instruction on analytics2 (e.g., topic modeling, social network analysis) of streaming data. This tutorial aims to provide practical strategies of information on reducing dimensionality using examples of big data. This tutorial will highlight strategies of incorporating domain experts and a comprehensive approach to streaming social media data.

Nitrogen processing by grazers in a headwater stream: riparian connections

DOE PAGES

Hill, Walter R.; Griffiths, Natalie A.

2016-10-19

Primary consumers play important roles in the cycling of nutrients in headwater streams, storing assimilated nutrients in growing tissue and recycling them through excretion. Though environmental conditions in most headwater streams and their surrounding terrestrial ecosystems vary considerably over the course of a year, relatively little is known about the effects of seasonality on consumer nutrient recycling these streams. Here, we measured nitrogen accumulated through growth and excreted by the grazing snail Elimia clavaeformis (Pleuroceridae) over the course of 12 months in Walker Branch, identifying close connections between in-stream nitrogen processing and seasonal changes in the surrounding forest.

Method and apparatus for separation of heavy and tritiated water

DOEpatents

Lee, Myung W.

2001-01-01

The present invention is a bi-thermal membrane process for separating and recovering hydrogen isotopes from a fluid containing hydrogen isotopes, such as water and hydrogen gas. The process in accordance with the present invention provides counter-current cold and hot streams of the fluid separated with a thermally insulating and chemically transparent proton exchange membrane (PEM). The two streams exchange hydrogen isotopes through the membrane: the heavier isotopes migrate into the cold stream, while the lighter isotopes migrate into the hot stream. The heavy and light isotopes are continuously withdrawn from the cold and hot streams respectively.

A multistream model of visual word recognition.

PubMed

Allen, Philip A; Smith, Albert F; Lien, Mei-Ching; Kaut, Kevin P; Canfield, Angie

2009-02-01

Four experiments are reported that test a multistream model of visual word recognition, which associates letter-level and word-level processing channels with three known visual processing streams isolated in macaque monkeys: the magno-dominated (MD) stream, the interblob-dominated (ID) stream, and the blob-dominated (BD) stream (Van Essen & Anderson, 1995). We show that mixing the color of adjacent letters of words does not result in facilitation of response times or error rates when the spatial-frequency pattern of a whole word is familiar. However, facilitation does occur when the spatial-frequency pattern of a whole word is not familiar. This pattern of results is not due to different luminance levels across the different-colored stimuli and the background because isoluminant displays were used. Also, the mixed-case, mixed-hue facilitation occurred when different display distances were used (Experiments 2 and 3), so this suggests that image normalization can adjust independently of object size differences. Finally, we show that this effect persists in both spaced and unspaced conditions (Experiment 4)--suggesting that inappropriate letter grouping by hue cannot account for these results. These data support a model of visual word recognition in which lower spatial frequencies are processed first in the more rapid MD stream. The slower ID and BD streams may process some lower spatial frequency information in addition to processing higher spatial frequency information, but these channels tend to lose the processing race to recognition unless the letter string is unfamiliar to the MD stream--as with mixed-case presentation.

The effects of road crossings on prairie stream habitat and function

USGS Publications Warehouse

Bouska, Wesley W.; Keane, Timothy; Paukert, Craig P.

2010-01-01

Improperly designed stream crossing structures may alter the form and function of stream ecosystems and habitat and prohibit the movement of aquatic organisms. Stream sections adjoining five concrete box culverts, five low-water crossings (concrete slabs vented by one or multiple culverts), and two large, single corrugated culvert vehicle crossings in eastern Kansas streams were compared to reference reaches using a geomorphologic survey and stream classification. Stream reaches were also compared upstream and downstream of crossings, and crossing measurements were used to determine which crossing design best mimicked the natural dimensions of the adjoining stream. Four of five low-water crossings, three of five box culverts, and one of two large, single corrugated pipe culverts changed classification from upstream to downstream of the crossings. Mean riffle spacing upstream at low-water crossings (8.6 bankfull widths) was double that of downstream reaches (mean 4.4 bankfull widths) but was similar upstream and downstream of box and corrugated pipe culverts. There also appeared to be greater deposition of fine sediments directly upstream of these designs. Box and corrugated culverts were more similar to natural streams than low-water crossings at transporting water, sediments, and debris during bankfull flows.

Presenting the master of all conductivity meters, and how it tastes streamflow

NASA Astrophysics Data System (ADS)

Weijs, S. V.; Parlange, M. B.

2012-04-01

For measuring streamflow in small Alpine streams, the salt dilution method is suitable and often used. By injecting a known mass of salt in the stream and measuring the downstream salt concentration as a function of time, we can obtain the streamflow by integration of the time signal. The underlying assumption is that the salt is well mixed within the stream cross-section. In this method, the salt concentration us usually measured through its relation with conductivity. Several commercial systems exist to do these conductivity measurements and automatically process the results. The problem we encountered when using these systems, however, is that uncertainty is often hidden under the hood. Because the processing happens onboard, researchers may be tempted to put too much trust in the final measurement outcomes. This is somewhat remediated by using a system with two probes which are individually processed to a streamflow outcome. We found that the salt-wave was differently shaped for the faster part of the stream compared to the sides, and therefore gave different readings for the discharge. To come a more probabilistic characterization of streamflow, and to know what is under the hood, we decided to build our own conductivity meter, equipped with eight probes covering the cross section. This enables quantifying some of the uncertainty in the streamflow measurements, which is important for testing hydrological models. This poster shows the first results and the hardware setup. We based our hardware on the open source hardware platform Arduino, and believe that by sharing both the design and the drawbacks, we contribute to the evolution of better measurement equipment or at least better understanding of its shortcomings.

COLA: Optimizing Stream Processing Applications via Graph Partitioning

NASA Astrophysics Data System (ADS)

Khandekar, Rohit; Hildrum, Kirsten; Parekh, Sujay; Rajan, Deepak; Wolf, Joel; Wu, Kun-Lung; Andrade, Henrique; Gedik, Buğra

In this paper, we describe an optimization scheme for fusing compile-time operators into reasonably-sized run-time software units called processing elements (PEs). Such PEs are the basic deployable units in System S, a highly scalable distributed stream processing middleware system. Finding a high quality fusion significantly benefits the performance of streaming jobs. In order to maximize throughput, our solution approach attempts to minimize the processing cost associated with inter-PE stream traffic while simultaneously balancing load across the processing hosts. Our algorithm computes a hierarchical partitioning of the operator graph based on a minimum-ratio cut subroutine. We also incorporate several fusion constraints in order to support real-world System S jobs. We experimentally compare our algorithm with several other reasonable alternative schemes, highlighting the effectiveness of our approach.

Processes and rates of sediment and wood accumulation in headwater streams of the Oregon Coast Range, USA

USGS Publications Warehouse

May, Christine L.; Gresswell, Robert E.

2003-01-01

Channels that have been scoured to bedrock by debris flows provide unique opportunities to calculate the rate of sediment and wood accumulation in low-order streams, to understand the temporal succession of channel morphology following disturbance, and to make inferences about processes associated with input and transport of sediment. Dendrochronology was used to estimate the time since the previous debris flow and the time since the last stand-replacement fire in unlogged basins in the central Coast Range of Oregon. Debris flow activity increased 42 per cent above the background rate in the decades immediately following the last wildfire. Changes in wood and sediment storage were quantified for 13 streams that ranged from 4 to 144 years since the previous debris flow. The volume of wood and sediment in the channel, and the length of channel with exposed bedrock, were strongly correlated with the time since the previous debris flow. Wood increased the storage capacity of the channel and trapped the majority of the sediment in these steep headwater streams. In the absence of wood, channels that have been scoured to bedrock by a debris flow may lack the capacity to store sediment and could persist in a bedrock state for an extended period of time. With an adequate supply of wood, low-order channels have the potential of storing large volumes of sediment in the interval between debris flows and can function as one of the dominant storage reservoirs for sediment in mountainous terrain.

Neural Signatures of Stimulus Features in Visual Working Memory—A Spatiotemporal Approach

PubMed Central

Jackson, Margaret C.; Klein, Christoph; Mohr, Harald; Shapiro, Kimron L.; Linden, David E. J.

2010-01-01

We examined the neural signatures of stimulus features in visual working memory (WM) by integrating functional magnetic resonance imaging (fMRI) and event-related potential data recorded during mental manipulation of colors, rotation angles, and color–angle conjunctions. The N200, negative slow wave, and P3b were modulated by the information content of WM, and an fMRI-constrained source model revealed a progression in neural activity from posterior visual areas to higher order areas in the ventral and dorsal processing streams. Color processing was associated with activity in inferior frontal gyrus during encoding and retrieval, whereas angle processing involved right parietal regions during the delay interval. WM for color–angle conjunctions did not involve any additional neural processes. The finding that different patterns of brain activity underlie WM for color and spatial information is consistent with ideas that the ventral/dorsal “what/where” segregation of perceptual processing influences WM organization. The absence of characteristic signatures of conjunction-related brain activity, which was generally intermediate between the 2 single conditions, suggests that conjunction judgments are based on the coordinated activity of these 2 streams. PMID:19429863

Source Apportionment of Suspended Sediment Sources using 137Cs and 210Pbxs

NASA Astrophysics Data System (ADS)

Lamba, J.; Karthikeyan, K.; Thompson, A.

2017-12-01

A study was conducted in the Pleasant Valley Watershed (50 km 2) in South Central Wisconsin to better understand sediment transport processes using sediment fingerprinting technique. Previous studies conducted in this watershed showed that resuspension of fine sediment deposited on the stream bed is an important source of suspended sediment. To better understand the role of fine sediment deposited on the stream bed, fallout radionuclides,137Cs and 210Pbxs were used to determine relative contribution to suspended sediment from in-stream (stream bank and stream bed) and upland sediment sources. Suspended sediment samples were collected during the crop growing season. Potential sources of suspended sediment considered in this study included cropland, pasture and in-stream (stream bed and stream bank). Suspended sediment sources were determined at a subwatershed level. Results of this study showed that in-stream sediment sources are important sources of suspended sediment. Future research should be conducted to better understand the role of legacy sediment in watershed-level sediment transport processes.

Training on Movement Figure-Ground Discrimination Remediates Low-Level Visual Timing Deficits in the Dorsal Stream, Improving High-Level Cognitive Functioning, Including Attention, Reading Fluency, and Working Memory.

PubMed

Lawton, Teri; Shelley-Tremblay, John

2017-01-01

The purpose of this study was to determine whether neurotraining to discriminate a moving test pattern relative to a stationary background, figure-ground discrimination, improves vision and cognitive functioning in dyslexics, as well as typically-developing normal students. We predict that improving the speed and sensitivity of figure-ground movement discrimination ( PATH to Reading neurotraining) acts to remediate visual timing deficits in the dorsal stream, thereby improving processing speed, reading fluency, and the executive control functions of attention and working memory in both dyslexic and normal students who had PATH neurotraining more than in those students who had no neurotraining. This prediction was evaluated by measuring whether dyslexic and normal students improved on standardized tests of cognitive skills following neurotraining exercises, more than following computer-based guided reading ( Raz-Kids ( RK )). The neurotraining used in this study was visually-based training designed to improve magnocellular function at both low and high levels in the dorsal stream: the input to the executive control networks coding working memory and attention. This approach represents a paradigm shift from the phonologically-based treatment for dyslexia, which concentrates on high-level speech and reading areas. This randomized controlled-validation study was conducted by training the entire second and third grade classrooms (42 students) for 30 min twice a week before guided reading. Standardized tests were administered at the beginning and end of 12-weeks of intervention training to evaluate improvements in academic skills. Only movement-discrimination training remediated both low-level visual timing deficits and high-level cognitive functioning, including selective and sustained attention, reading fluency and working memory for both dyslexic and normal students. Remediating visual timing deficits in the dorsal stream revealed the causal role of visual movement discrimination training in improving high-level cognitive functions such as attention, reading acquisition and working memory. This study supports the hypothesis that faulty timing in synchronizing the activity of magnocellular with parvocellular visual pathways in the dorsal stream is a fundamental cause of dyslexia and being at-risk for reading problems in normal students, and argues against the assumption that reading deficiencies in dyslexia are caused by phonological or language deficits, requiring a paradigm shift from phonologically-based treatment of dyslexia to a visually-based treatment. This study shows that visual movement-discrimination can be used not only to diagnose dyslexia early, but also for its successful treatment, so that reading problems do not prevent children from readily learning.

Training on Movement Figure-Ground Discrimination Remediates Low-Level Visual Timing Deficits in the Dorsal Stream, Improving High-Level Cognitive Functioning, Including Attention, Reading Fluency, and Working Memory

PubMed Central

Lawton, Teri; Shelley-Tremblay, John

2017-01-01

The purpose of this study was to determine whether neurotraining to discriminate a moving test pattern relative to a stationary background, figure-ground discrimination, improves vision and cognitive functioning in dyslexics, as well as typically-developing normal students. We predict that improving the speed and sensitivity of figure-ground movement discrimination (PATH to Reading neurotraining) acts to remediate visual timing deficits in the dorsal stream, thereby improving processing speed, reading fluency, and the executive control functions of attention and working memory in both dyslexic and normal students who had PATH neurotraining more than in those students who had no neurotraining. This prediction was evaluated by measuring whether dyslexic and normal students improved on standardized tests of cognitive skills following neurotraining exercises, more than following computer-based guided reading (Raz-Kids (RK)). The neurotraining used in this study was visually-based training designed to improve magnocellular function at both low and high levels in the dorsal stream: the input to the executive control networks coding working memory and attention. This approach represents a paradigm shift from the phonologically-based treatment for dyslexia, which concentrates on high-level speech and reading areas. This randomized controlled-validation study was conducted by training the entire second and third grade classrooms (42 students) for 30 min twice a week before guided reading. Standardized tests were administered at the beginning and end of 12-weeks of intervention training to evaluate improvements in academic skills. Only movement-discrimination training remediated both low-level visual timing deficits and high-level cognitive functioning, including selective and sustained attention, reading fluency and working memory for both dyslexic and normal students. Remediating visual timing deficits in the dorsal stream revealed the causal role of visual movement discrimination training in improving high-level cognitive functions such as attention, reading acquisition and working memory. This study supports the hypothesis that faulty timing in synchronizing the activity of magnocellular with parvocellular visual pathways in the dorsal stream is a fundamental cause of dyslexia and being at-risk for reading problems in normal students, and argues against the assumption that reading deficiencies in dyslexia are caused by phonological or language deficits, requiring a paradigm shift from phonologically-based treatment of dyslexia to a visually-based treatment. This study shows that visual movement-discrimination can be used not only to diagnose dyslexia early, but also for its successful treatment, so that reading problems do not prevent children from readily learning. PMID:28555097

40 CFR 65.149 - Boilers and process heaters.

Code of Federal Regulations, 2010 CFR

2010-07-01

... stream is not introduced as or with the primary fuel, a temperature monitoring device in the fire box...-throughput transfer racks, as applicable, shall meet the requirements of this section. (2) The vent stream... thermal units per hour) or greater. (ii) A boiler or process heater into which the vent stream is...

40 CFR 63.1082 - What definitions do I need to know?

Code of Federal Regulations, 2011 CFR

2011-07-01

... includes direct-contact cooling water. Spent caustic waste stream means the continuously flowing process... compounds from process streams, typically cracked gas. The spent caustic waste stream does not include spent..., and the C4 butadiene storage equipment; and spent wash water from the C4 crude butadiene carbonyl wash...

40 CFR 63.1082 - What definitions do I need to know?

Code of Federal Regulations, 2012 CFR

2012-07-01

... includes direct-contact cooling water. Spent caustic waste stream means the continuously flowing process... compounds from process streams, typically cracked gas. The spent caustic waste stream does not include spent..., and the C4 butadiene storage equipment; and spent wash water from the C4 crude butadiene carbonyl wash...

40 CFR 63.1082 - What definitions do I need to know?

Code of Federal Regulations, 2014 CFR

2014-07-01

... includes direct-contact cooling water. Spent caustic waste stream means the continuously flowing process... compounds from process streams, typically cracked gas. The spent caustic waste stream does not include spent..., and the C4 butadiene storage equipment; and spent wash water from the C4 crude butadiene carbonyl wash...

40 CFR 63.1082 - What definitions do I need to know?

Code of Federal Regulations, 2013 CFR

2013-07-01

... includes direct-contact cooling water. Spent caustic waste stream means the continuously flowing process... compounds from process streams, typically cracked gas. The spent caustic waste stream does not include spent..., and the C4 butadiene storage equipment; and spent wash water from the C4 crude butadiene carbonyl wash...

M-Stream Deficits and Reading-Related Visual Processes in Developmental Dyslexia

ERIC Educational Resources Information Center

Boden, Catherine; Giaschi, Deborah

2007-01-01

Some visual processing deficits in developmental dyslexia have been attributed to abnormalities in the subcortical M stream and/or the cortical dorsal stream of the visual pathways. The nature of the relationship between these visual deficits and reading is unknown. The purpose of the present article was to characterize reading-related perceptual…

Reduced functional connectivity between V1 and inferior frontal cortex associated with visuomotor performance in autism

PubMed Central

Villalobos, Michele E.; Mizuno, Akiko; Dahl, Branelle C.; Kemmotsu, Nobuko; Müller, Ralph-Axel

2010-01-01

Some recent evidence has suggested abnormalities of the dorsal stream and possibly the mirror neuron system in autism, which may be responsible for impairments of joint attention, imitation, and secondarily for language delays. The current study investigates functional connectivity along the dorsal stream in autism, examining interregional blood oxygenation level dependent (BOLD) signal cross-correlation during visuomotor coordination. Eight high-functioning autistic men and 8 handedness and age-matched controls were included. Visually prompted button presses were performed with the preferred hand. For each subject, functional connectivity was computed in terms of BOLD signal correlation with the mean time series in bilateral visual area 17. Our hypothesis of reduced dorsal stream connectivity in autism was only in part confirmed. Functional connectivity with superior parietal areas was not significantly reduced. However, the autism group showed significantly reduced connectivity with bilateral inferior frontal area 44, which is compatible with the hypothesis of mirror neuron defects in autism. More generally, our findings suggest that dorsal stream connectivity in autism may not be fully functional. PMID:15808991

Reduced functional connectivity between V1 and inferior frontal cortex associated with visuomotor performance in autism.

PubMed

Villalobos, Michele E; Mizuno, Akiko; Dahl, Branelle C; Kemmotsu, Nobuko; Müller, Ralph-Axel

2005-04-15

Some recent evidence has suggested abnormalities of the dorsal stream and possibly the mirror neuron system in autism, which may be responsible for impairments of joint attention, imitation, and secondarily for language delays. The current study investigates functional connectivity along the dorsal stream in autism, examining interregional blood oxygenation level dependent (BOLD) signal cross-correlation during visuomotor coordination. Eight high-functioning autistic men and eight handedness and age-matched controls were included. Visually prompted button presses were performed with the preferred hand. For each subject, functional connectivity was computed in terms of BOLD signal correlation with the mean time series in bilateral visual area 17. Our hypothesis of reduced dorsal stream connectivity in autism was only in part confirmed. Functional connectivity with superior parietal areas was not significantly reduced. However, the autism group showed significantly reduced connectivity with bilateral inferior frontal area 44, which is compatible with the hypothesis of mirror neuron defects in autism. More generally, our findings suggest that dorsal stream connectivity in autism may not be fully functional.

Streaming data analytics via message passing with application to graph algorithms

DOE PAGES

Plimpton, Steven J.; Shead, Tim

2014-05-06

The need to process streaming data, which arrives continuously at high-volume in real-time, arises in a variety of contexts including data produced by experiments, collections of environmental or network sensors, and running simulations. Streaming data can also be formulated as queries or transactions which operate on a large dynamic data store, e.g. a distributed database. We describe a lightweight, portable framework named PHISH which enables a set of independent processes to compute on a stream of data in a distributed-memory parallel manner. Datums are routed between processes in patterns defined by the application. PHISH can run on top of eithermore » message-passing via MPI or sockets via ZMQ. The former means streaming computations can be run on any parallel machine which supports MPI; the latter allows them to run on a heterogeneous, geographically dispersed network of machines. We illustrate how PHISH can support streaming MapReduce operations, and describe streaming versions of three algorithms for large, sparse graph analytics: triangle enumeration, subgraph isomorphism matching, and connected component finding. Lastly, we also provide benchmark timings for MPI versus socket performance of several kernel operations useful in streaming algorithms.« less

Method and apparatus for producing oxygen and nitrogen and membrane therefor

DOEpatents

Roman, I.C.; Baker, R.W.

1985-09-17

Process and apparatus for the separation and purification of oxygen and nitrogen as well as a novel membrane useful therein are disclosed. The process utilizes novel facilitated transport membranes to selectively transport oxygen from one gaseous stream to another, leaving nitrogen as a byproduct. In the method, an oxygen carrier capable of reversibly binding molecular oxygen is dissolved in a polar organic membrane which separates a gaseous feed stream such as atmospheric air and a gaseous product stream. The feed stream is maintained at a sufficiently high oxygen pressure to keep the oxygen carrier in its oxygenated form at the interface of the feed stream with the membrane, while the product stream is maintained at a sufficiently low oxygen pressure to keep the carrier in its deoxygenated form at the interface of the product stream with the membrane. In an alternate mode of operation, the feed stream is maintained at a sufficiently low temperature and high oxygen pressure to keep the oxygen carrier in its oxygenated form at the interface of the feed stream with the membrane and the product stream is maintained at a sufficiently high temperature to keep the carrier in its deoxygenated form at the interface of the product stream with the membrane. Under such conditions, the carrier acts as a shuttle, picking up oxygen at the feed side of the membrane, diffusing across the membrane as the oxygenated complex, releasing oxygen to the product stream, and then diffusing back to the feed side to repeat the process. Exceptionally and unexpectedly high O[sub 2]/N[sub 2] selectivity, on the order of 10 to 30, is obtained, as well as exceptionally high oxygen permeability, on the order of 6 to 15 [times] 10[sup [minus]8] cm[sup 3]-cm/cm[sup 2]-sec-cmHg, as well as a long membrane life of in excess of 3 months, making the process commercially feasible. 2 figs.

Method and apparatus for producing oxygen and nitrogen and membrane therefor

DOEpatents

Roman, Ian C.; Baker, Richard W.

1985-01-01

Process and apparatus for the separation and purification of oxygen and nitrogen as well as a novel membrane useful therein are disclosed. The process utilizes novel facilitated transport membranes to selectively transport oxygen from one gaseous stream to another, leaving nitrogen as a byproduct. In the method, an oxygen carrier capable of reversibly binding molecular oxygen is dissolved in a polar organic membrane which separates a gaseous feed stream such as atmospheric air and a gaseous product stream. The feed stream is maintained at a sufficiently high oxygen pressure to keep the oxygen carrier in its oxygenated form at the interface of the feed stream with the membrane, while the product stream is maintained at a sufficiently low oxygen pressure to keep the carrier in its deoxygenated form at the interface of the product stream with the membrane. In an alternate mode of operation, the feed stream is maintained at a sufficiently low temperature and high oxygen pressure to keep the oxygen carrier in its oxygenated form at the interface of the feed stream with the membrane and the product stream is maintained at a sufficiently high temperature to keep the carrier in its deoxygenated form at the interface of the product stream with the membrane. Under such conditions, the carrier acts as a shuttle, picking up oxygen at the feed side of the membrane, diffusing across the membrane as the oxygenated complex, releasing oxygen to the product stream, and then diffusing back to the feed side to repeat the process. Exceptionally and unexpectedly high O.sub.2 /N.sub.2 selectivity, on the order of 10 to 30, is obtained, as well as exceptionally high oxygen permeability, on the order of 6 to 15.times.10.sup.-8 cm.sup.3 -cm/cm.sup.2 -sec-cmHg, as well as a long membrane life of in excess of 3 months, making the process commercially feasible.

Nematomorph parasites indirectly alter the food web and ecosystem function of streams through behavioural manipulation of their cricket hosts.

PubMed

Sato, Takuya; Egusa, Tomohiro; Fukushima, Keitaro; Oda, Tomoki; Ohte, Nobuhito; Tokuchi, Naoko; Watanabe, Katsutoshi; Kanaiwa, Minoru; Murakami, Isaya; Lafferty, Kevin D

2012-08-01

Nematomorph parasites manipulate crickets to enter streams where the parasites reproduce. These manipulated crickets become a substantial food subsidy for stream fishes. We used a field experiment to investigate how this subsidy affects the stream community and ecosystem function. When crickets were available, predatory fish ate fewer benthic invertebrates. The resulting release of the benthic invertebrate community from fish predation indirectly decreased the biomass of benthic algae and slightly increased leaf break-down rate. This is the first experimental demonstration that host manipulation by a parasite can reorganise a community and alter ecosystem function. Nematomorphs are common, and many other parasites have dramatic effects on host phenotypes, suggesting that similar effects of parasites on ecosystems might be widespread. © 2012 Blackwell Publishing Ltd/CNRS.

Nematomorph parasites indirectly alter the food web and ecosystem function of streams through behavioural manipulation of their cricket hosts.

USGS Publications Warehouse

Sato, T.; Egusa, T.; Fukushima, K.; Oda, T.; Ohte, N.; Tokuchi, Naoko; Watanabe, Katsutoshi; Kanaiwa, Minoru; Murakami, Isaya; Lafferty, Kevin D.

2012-01-01

Nematomorph parasites manipulate crickets to enter streams where the parasites reproduce. These manipulated crickets become a substantial food subsidy for stream fishes. We used a field experiment to investigate how this subsidy affects the stream community and ecosystem function. When crickets were available, predatory fish ate fewer benthic invertebrates. The resulting release of the benthic invertebrate community from fish predation indirectly decreased the biomass of benthic algae and slightly increased leaf break-down rate. This is the first experimental demonstration that host manipulation by a parasite can reorganise a community and alter ecosystem function. Nematomorphs are common, and many other parasites have dramatic effects on host phenotypes, suggesting that similar effects of parasites on ecosystems might be widespread.

Compliance of secondary production and eco-exergy as indicators of benthic macroinvertebrates assemblages' response to canopy cover conditions in Neotropical headwater streams.

PubMed

Linares, Marden Seabra; Callisto, Marcos; Marques, João Carlos

2018-02-01

Riparian vegetation cover influences benthic assemblages structure and functioning in headwater streams, as it regulates light availability and autochthonous primary production in these ecosystems.Secondary production, diversity, and exergy-based indicators were applied in capturing how riparian cover influences the structure and functioning of benthic macroinvertebrate assemblages in tropical headwater streams. Four hypotheses were tested: (1) open canopy will determine the occurrence of higher diversity in benthic macroinvertebrate assemblages; (2) streams with open canopy will exhibit more complex benthic macroinvertebrate communities (in terms of information embedded in the organisms' biomass); (3) in streams with open canopy benthic macroinvertebrate assemblages will be more efficient in using the available resources to build structure, which will be reflected by higher eco-exergy values; (4) benthic assemblages in streams with open canopy will exhibit more secondary productivity. We selected eight non-impacted headwater streams, four shaded and four with open canopy, all located in the Neotropical savannah (Cerrado) of southeastern Brazil. Open canopy streams consistently exhibited significantly higher eco-exergy and instant secondary production values, exemplifying that these streams may support more complex and productive benthic macroinvertebrate assemblages. Nevertheless, diversity indices and specific eco-exergy were not significantly different in shaded and open canopy streams. Since all the studied streams were selected for being considered as non-impacted, this suggests that the potential represented by more available food resources was not used to build a more complex dissipative structure. These results illustrate the role and importance of the canopy cover characteristics on the structure and functioning of benthic macroinvertebrate assemblages in tropical headwater streams, while autochthonous production appears to play a crucial role as food source for benthic macroinvertebrates. This study also highlights the possible application of thermodynamic based indicators as tools to guide environmental managers in developing and implementing policies in the neotropical savannah. Copyright © 2017 Elsevier B.V. All rights reserved.

A simple-harmonic model for depicting the annual cycle of seasonal temperatures of streams

USGS Publications Warehouse

Steele, Timothy Doak

1978-01-01

Due to economic or operational constraints, stream-temperature records cannot always be collected at all sites where information is desired or at frequencies dictated by continuous or near-continuous surveillance requirements. For streams where only periodic measurements are made during the year, and that are not appreciably affected by regulation or by thermal loading , a simple harmonic function may adequately depict the annual seasonal cycle of stream temperature at any given site. Resultant harmonic coefficients obtained from available stream-temperature records may be used in the following ways: (1) To interpolate between discrete measurements by solving the harmonic function at specified times, thereby filling in estimates of stream-temperature values; (2) to characterize areal or regional patterns of natural stream-temperature values; (2) to characterize areal or regional patterns of natural stream-temperature conditions; and (3) to detect and to assess any significant at a site brought about by streamflow regulation or basin development. Moreover, less-than-daily or sampling frequencies at a given site may give estimates of annual variation of stream temperatures that are statistically comparable to estimates obtained from a daily or continuous sampling scheme. The latter procedure may result in potential savings of resources in network operations, with negligible loss in information on annual stream-temperature variations. (Woodard -USGS)

40 CFR 63.11970 - What are my initial compliance requirements for process wastewater?

Code of Federal Regulations, 2014 CFR

2014-07-01

... requirements for process wastewater? 63.11970 Section 63.11970 Protection of Environment ENVIRONMENTAL... What are my initial compliance requirements for process wastewater? (a) Demonstration of initial compliance for process wastewater streams that must be treated. For each process wastewater stream that must...

40 CFR 63.11970 - What are my initial compliance requirements for process wastewater?

Code of Federal Regulations, 2013 CFR

2013-07-01

... requirements for process wastewater? 63.11970 Section 63.11970 Protection of Environment ENVIRONMENTAL... What are my initial compliance requirements for process wastewater? (a) Demonstration of initial compliance for process wastewater streams that must be treated. For each process wastewater stream that must...

40 CFR 63.11970 - What are my initial compliance requirements for process wastewater?

Code of Federal Regulations, 2012 CFR

2012-07-01

... requirements for process wastewater? 63.11970 Section 63.11970 Protection of Environment ENVIRONMENTAL... What are my initial compliance requirements for process wastewater? (a) Demonstration of initial compliance for process wastewater streams that must be treated. For each process wastewater stream that must...

Low-Cutoff, High-Pass Digital Filtering of Neural Signals

NASA Technical Reports Server (NTRS)

Mojarradi,Mohammad; Johnson, Travis; Ortiz, Monico; Cunningham, Thomas; Andersen, Richard

2004-01-01

The figure depicts the major functional blocks of a system, now undergoing development, for conditioning neural signals acquired by electrodes implanted in a brain. The overall functions to be performed by this system can be summarized as preamplification, multiplexing, digitization, and high-pass filtering. Other systems under development for recording neural signals typically contain resistor-capacitor analog low-pass filters characterized by cutoff frequencies in the vicinity of 100 Hz. In the application for which this system is being developed, there is a requirement for a cutoff frequency of 5 Hz. Because the resistors needed to obtain such a low cutoff frequency would be impractically large, it was decided to perform low-pass filtering by use of digital rather than analog circuitry. In addition, it was decided to timemultiplex the digitized signals from the multiple input channels into a single stream of data in a single output channel. The signal in each input channel is first processed by a preamplifier having a voltage gain of approximately 50. Embedded in each preamplifier is a low-pass anti-aliasing filter having a cutoff frequency of approximately 10 kHz. The anti-aliasing filters make it possible to couple the outputs of the preamplifiers to the input ports of a multiplexer. The output of the multiplexer is a single stream of time-multiplexed samples of analog signals. This stream is processed by a main differential amplifier, the output of which is sent to an analog-to-digital converter (ADC). The output of the ADC is sent to a digital signal processor (DSP).

Increasing fish taxonomic and functional richness affects ecosystem properties of small headwater prairie streams

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

Martin, Erika C.; Gido, Keith B.; Bello, Nora

Stream fish can regulate their environment through direct and indirect pathways, and the relative influence of communities with different taxonomic and functional richness on ecosystem properties likely depends on habitat structure. Given this complexity, it is not surprising that observational studies of how stream fish communities influence ecosystems have shown mixed results. In this study, we evaluated the effect of an observed gradient of taxonomic (zero, one, two or three species) and functional (zero, one or two groups) richness of fishes on several key ecosystem properties in experimental stream mesocosms. Our study simulated small (less than two metres wide) headwatermore » prairie streams with a succession of three pool-riffle structures (upstream, middle and downstream) per mesocosm. Additionally, ecosystem responses included chlorophyll a from floating algal mats and benthic algae, benthic organic matter, macroinvertebrates (all as mass per unit area), algal filament length and stream metabolism (photosynthesis and respiration rate). Ecosystem responses were analysed individually using general linear mixed models. Significant treatment (taxonomic and functional richness) by habitat (pools and riffles) interactions were found for all but one ecosystem response variable. After accounting for location (upstream, middle and downstream) effects, the presence of one or two grazers resulted in shorter mean algal filament lengths in pools compared to no-fish controls. These observations suggest grazers can maintain short algal filaments in pools, which may inhibit long filaments from reaching the surface. Accordingly, floating algal mats decreased in mid- and downstream locations in grazer treatment relative to no-fish controls. At the scale of the entire reach, gross primary productivity and respiration were greater in treatments with two grazer species compared to mixed grazer/insectivore or control treatments. Lastly, the distribution of stream resources across habitat types and locations within a reach can therefore be influenced by the taxonomic and functional composition of fishes in small prairie streams. Thus, disturbances that alter diversity of these systems might have unexpected ecosystem-level consequences.« less

Increasing fish taxonomic and functional richness affects ecosystem properties of small headwater prairie streams

DOE PAGES

Martin, Erika C.; Gido, Keith B.; Bello, Nora; ...

2016-04-06

Stream fish can regulate their environment through direct and indirect pathways, and the relative influence of communities with different taxonomic and functional richness on ecosystem properties likely depends on habitat structure. Given this complexity, it is not surprising that observational studies of how stream fish communities influence ecosystems have shown mixed results. In this study, we evaluated the effect of an observed gradient of taxonomic (zero, one, two or three species) and functional (zero, one or two groups) richness of fishes on several key ecosystem properties in experimental stream mesocosms. Our study simulated small (less than two metres wide) headwatermore » prairie streams with a succession of three pool-riffle structures (upstream, middle and downstream) per mesocosm. Additionally, ecosystem responses included chlorophyll a from floating algal mats and benthic algae, benthic organic matter, macroinvertebrates (all as mass per unit area), algal filament length and stream metabolism (photosynthesis and respiration rate). Ecosystem responses were analysed individually using general linear mixed models. Significant treatment (taxonomic and functional richness) by habitat (pools and riffles) interactions were found for all but one ecosystem response variable. After accounting for location (upstream, middle and downstream) effects, the presence of one or two grazers resulted in shorter mean algal filament lengths in pools compared to no-fish controls. These observations suggest grazers can maintain short algal filaments in pools, which may inhibit long filaments from reaching the surface. Accordingly, floating algal mats decreased in mid- and downstream locations in grazer treatment relative to no-fish controls. At the scale of the entire reach, gross primary productivity and respiration were greater in treatments with two grazer species compared to mixed grazer/insectivore or control treatments. Lastly, the distribution of stream resources across habitat types and locations within a reach can therefore be influenced by the taxonomic and functional composition of fishes in small prairie streams. Thus, disturbances that alter diversity of these systems might have unexpected ecosystem-level consequences.« less

Integrating complex business processes for knowledge-driven clinical decision support systems.

PubMed

Kamaleswaran, Rishikesan; McGregor, Carolyn

2012-01-01

This paper presents in detail the component of the Complex Business Process for Stream Processing framework that is responsible for integrating complex business processes to enable knowledge-driven Clinical Decision Support System (CDSS) recommendations. CDSSs aid the clinician in supporting the care of patients by providing accurate data analysis and evidence-based recommendations. However, the incorporation of a dynamic knowledge-management system that supports the definition and enactment of complex business processes and real-time data streams has not been researched. In this paper we discuss the process web service as an innovative method of providing contextual information to a real-time data stream processing CDSS.

Method for processing aqueous wastes

DOEpatents

Pickett, John B.; Martin, Hollis L.; Langton, Christine A.; Harley, Willie W.

1993-01-01

A method for treating waste water such as that from an industrial processing facility comprising the separation of the waste water into a dilute waste stream and a concentrated waste stream. The concentrated waste stream is treated chemically to enhance precipitation and then allowed to separate into a sludge and a supernate. The supernate is skimmed or filtered from the sludge and blended with the dilute waste stream to form a second dilute waste stream. The sludge remaining is mixed with cementitious material, rinsed to dissolve soluble components, then pressed to remove excess water and dissolved solids before being allowed to cure. The dilute waste stream is also chemically treated to decompose carbonate complexes and metal ions and then mixed with cationic polymer to cause the precipitated solids to flocculate. Filtration of the flocculant removes sufficient solids to allow the waste water to be discharged to the surface of a stream. The filtered material is added to the sludge of the concentrated waste stream. The method is also applicable to the treatment and removal of soluble uranium from aqueous streams, such that the treated stream may be used as a potable water supply.

Physical habitat simulation system reference manual: version II

USGS Publications Warehouse

Milhous, Robert T.; Updike, Marlys A.; Schneider, Diane M.

1989-01-01

There are four major components of a stream system that determine the productivity of the fishery (Karr and Dudley 1978). These are: (1) flow regime, (2) physical habitat structure (channel form, substrate distribution, and riparian vegetation), (3) water quality (including temperature), and (4) energy inputs from the watershed (sediments, nutrients, and organic matter). The complex interaction of these components determines the primary production, secondary production, and fish population of the stream reach. The basic components and interactions needed to simulate fish populations as a function of management alternatives are illustrated in Figure I.1. The assessment process utilizes a hierarchical and modular approach combined with computer simulation techniques. The modular components represent the "building blocks" for the simulation. The quality of the physical habitat is a function of flow and, therefore, varies in quality and quantity over the range of the flow regime. The conceptual framework of the Incremental Methodology and guidelines for its application are described in "A Guide to Stream Habitat Analysis Using the Instream Flow Incremental Methodology" (Bovee 1982). Simulation of physical habitat is accomplished using the physical structure of the stream and streamflow. The modification of physical habitat by temperature and water quality is analyzed separately from physical habitat simulation. Temperature in a stream varies with the seasons, local meteorological conditions, stream network configuration, and the flow regime; thus, the temperature influences on habitat must be analysed on a stream system basis. Water quality under natural conditions is strongly influenced by climate and the geological materials, with the result that there is considerable natural variation in water quality. When we add the activities of man, the possible range of water quality possibilities becomes rather large. Consequently, water quality must also be analysed on a stream system basis. Such analysis is outside the scope of this manual, which concentrates on simulation of physical habitat based on depth, velocity, and a channel index. The results form PHABSIM can be used alone or by using a series of habitat time series programs that have been developed to generate monthly or daily habitat time series from the Weighted Usable Area versus streamflow table resulting from the habitat simulation programs and streamflow time series data. Monthly and daily streamflow time series may be obtained from USGS gages near the study site or as the output of river system management models.

Reconciling records of ice streaming and ice margin retreat to produce a palaeogeographic reconstruction of the deglaciation of the Laurentide Ice Sheet

NASA Astrophysics Data System (ADS)

Margold, Martin; Stokes, Chris R.; Clark, Chris D.

2018-06-01

This paper reconstructs the deglaciation of the Laurentide Ice Sheet (LIS; including the Innuitian Ice Sheet) from the Last Glacial Maximum (LGM), with a particular focus on the spatial and temporal variations in ice streaming and the associated changes in flow patterns and ice divides. We build on a recent inventory of Laurentide ice streams and use an existing ice margin chronology to produce the first detailed transient reconstruction of the ice stream drainage network in the LIS, which we depict in a series of palaeogeographic maps. Results show that the drainage network at the LGM was similar to modern-day Antarctica. The majority of the ice streams were marine terminating and topographically-controlled and many of these continued to function late into the deglaciation, until the ice sheet lost its marine margin. Ice streams with a terrestrial ice margin in the west and south were more transient and ice flow directions changed with the build-up, peak-phase and collapse of the Cordilleran-Laurentide ice saddle. The south-eastern marine margin in Atlantic Canada started to retreat relatively early and some of the ice streams in this region switched off at or shortly after the LGM. In contrast, the ice streams draining towards the north-western and north-eastern marine margins in the Beaufort Sea and in Baffin Bay appear to have remained stable throughout most of the Late Glacial, and some of them continued to function until after the Younger Dryas (YD). The YD influenced the dynamics of the deglaciation, but there remains uncertainty about the response of the ice sheet in several sectors. We tentatively ascribe the switching-on of some major ice streams during this period (e.g. M'Clintock Channel Ice Stream at the north-west margin), but for other large ice streams whose timing partially overlaps with the YD, the drivers are less clear and ice-dynamical processes, rather than effects of climate and surface mass balance are viewed as more likely drivers. Retreat rates markedly increased after the YD and the ice sheet became limited to the Canadian Shield. This hard-bed substrate brought a change in the character of ice streaming, which became less frequent but generated much broader terrestrial ice streams. The final collapse of the ice sheet saw a series of small ephemeral ice streams that resulted from the rapidly changing ice sheet geometry in and around Hudson Bay. Our reconstruction indicates that the LIS underwent a transition from a topographically-controlled ice drainage network at the LGM to an ice drainage network characterised by less frequent, broad ice streams during the later stages of deglaciation. These deglacial ice streams are mostly interpreted as a reaction to localised ice-dynamical forcing (flotation and calving of the ice front in glacial lakes and transgressing sea; basal de-coupling due to large amount of meltwater reaching the bed, debuttressing due to rapid changes in ice sheet geometry) rather than as conveyors of excess mass from the accumulation area of the ice sheet. At an ice sheet scale, the ice stream drainage network became less widespread and less efficient with the decreasing size of the deglaciating ice sheet, the final elimination of which was mostly driven by surface melt.

A new neural framework for visuospatial processing.

PubMed

Kravitz, Dwight J; Saleem, Kadharbatcha S; Baker, Chris I; Mishkin, Mortimer

2011-04-01

The division of cortical visual processing into distinct dorsal and ventral streams is a key framework that has guided visual neuroscience. The characterization of the ventral stream as a 'What' pathway is relatively uncontroversial, but the nature of dorsal stream processing is less clear. Originally proposed as mediating spatial perception ('Where'), more recent accounts suggest it primarily serves non-conscious visually guided action ('How'). Here, we identify three pathways emerging from the dorsal stream that consist of projections to the prefrontal and premotor cortices, and a major projection to the medial temporal lobe that courses both directly and indirectly through the posterior cingulate and retrosplenial cortices. These three pathways support both conscious and non-conscious visuospatial processing, including spatial working memory, visually guided action and navigation, respectively.

Spatial dynamics of overbank sedimentation in floodplain systems

USGS Publications Warehouse

Pierce, Aaron R.; King, S.L.

2008-01-01

Floodplains provide valuable social and ecological functions, and understanding the rates and patterns of overbank sedimentation is critical for river basin management and rehabilitation. Channelization of alluvial systems throughout the world has altered hydrological and sedimentation processes within floodplain ecosystems. In the loess belt region of the Lower Mississippi Alluvial Valley of the United States, channelization, the geology of the region, and past land-use practices have resulted in the formation of dozens of valley plugs in stream channels and the formation of shoals at the confluence of stream systems. Valley plugs completely block stream channels with sediment and debris and can result in greater deposition rates on floodplain surfaces. Presently, however, information is lacking on the rates and variability of overbank sedimentation associated with valley plugs and shoals. We quantified deposition rates and textures in floodplains along channelized streams that contained valley plugs and shoals, in addition to floodplains occurring along an unchannelized stream, to improve our understanding of overbank sedimentation associated with channelized streams. Feldspar clay marker horizons and marker poles were used to measure floodplain deposition from 2002 to 2005 and data were analyzed with geospatial statistics to determine the spatial dynamics of sedimentation within the floodplains. Mean sediment deposition rates ranged from 0.09 to 0.67??cm/y at unchannelized sites, 0.16 to 2.27??cm/y at shoal sites, and 3.44 to 6.20??cm/y at valley plug sites. Valley plug sites had greater rates of deposition, and the deposited sediments contained more coarse sand material than either shoal or unchannelized sites. A total of 59 of 183 valley plug study plots had mean deposition rates > 5??cm/y. The geospatial analyses showed that the spatial dynamics of sedimentation can be influenced by the formation of valley plugs and shoals on channelized streams; however, responses can vary. Restoration efforts in the region need to have basinwide collaboration with landowners and address catchment-scale processes, including the geomorphic instability of the region, to be successful. ?? 2008 Elsevier B.V. All rights reserved.

Nitrification and denitrification in a midwestern stream containing high nitrate: In situ assessment using tracers in dome-shaped incubation chambers

USGS Publications Warehouse

Smith, R.L.; Böhlke, J.K.; Repert, D.A.; Hart, C.P.

2009-01-01

The extent to which in-stream processes alter or remove nutrient loads in agriculturally impacted streams is critically important to watershed function and the delivery of those loads to coastal waters. In this study, patch-scale rates of in-stream benthic processes were determined using large volume, open-bottom benthic incubation chambers in a nitrate-rich, first to third order stream draining an area dominated by tile-drained row-crop fields. The chambers were fitted with sampling/mixing ports, a volume compensation bladder, and porewater samplers. Incubations were conducted with added tracers (NaBr and either 15N[NO3-], 15N[NO2-], or 15N[NH4+]) for 24-44 h intervals and reaction rates were determined from changes in concentrations and isotopic compositions of nitrate, nitrite, ammonium and nitrogen gas. Overall, nitrate loss rates (220-3,560 ??mol N m-2 h-1) greatly exceeded corresponding denitrification rates (34-212 ??mol N m-2 h-1) and both of these rates were correlated with nitrate concentrations (90-1,330 ??M), which could be readily manipulated with addition experiments. Chamber estimates closely matched whole-stream rates of denitrification and nitrate loss using 15N. Chamber incubations with acetylene indicated that coupled nitrification/denitrification was not a major source of N2 production at ambient nitrate concentrations (175 ??M), but acetylene was not effective for assessing denitrification at higher nitrate concentrations (1,330 ??M). Ammonium uptake rates greatly exceeded nitrification rates, which were relatively low even with added ammonium (3.5 ??mol N m-2 h-1), though incubations with nitrite demonstrated that oxidation to nitrate exceeded reduction to nitrogen gas in the surface sediments by fivefold to tenfold. The chamber results confirmed earlier studies that denitrification was a substantial nitrate sink in this stream, but they also indicated that dissolved inorganic nitrogen (DIN) turnover rates greatly exceeded the rates of permanent nitrogen removal via denitrification. ?? Springer Science+Business Media B.V. 2009.

Cooling and solidification of heavy hydrocarbon liquid streams

DOEpatents

Antieri, Salvatore J.; Comolli, Alfred G.

1983-01-01

A process and apparatus for cooling and solidifying a stream of heavy hydrocarbon material normally boiling above about 850.degree. F., such as vacuum bottoms material from a coal liquefaction process. The hydrocarbon stream is dropped into a liquid bath, preferably water, which contains a screw conveyor device and the stream is rapidly cooled, solidified and broken therein to form discrete elongated particles. The solid extrudates or prills are then dried separately to remove substantially all surface moisture, and passed to further usage.

Featured collection introduction: Connectivity of streams and wetlands to downstream waters

USGS Publications Warehouse

Alexander, Laurie C.; Fritz, Ken M.; Schofield, Kate; Autrey, Bradley; DeMeester, Julie; Golden, Heather E.; Goodrich, David C.; Kepner, William G.; Kiperwas, Hadas R.; Lane, Charles R.; LeDuc, Stephen D.; Leibowitz, Scott; McManus, Michael G.; Pollard, Amina I.; Ridley, Caroline E.; Vanderhoof, Melanie; Wigington, Parker J.

2018-01-01

Connectivity is a fundamental but highly dynamic property of watersheds. Variability in the types and degrees of aquatic ecosystem connectivity presents challenges for researchers and managers seeking to accurately quantify its effects on critical hydrologic, biogeochemical, and biological processes. However, protecting natural gradients of connectivity is key to protecting the range of ecosystem services that aquatic ecosystems provide. In this featured collection, we review the available evidence on connections and functions by which streams and wetlands affect the integrity of downstream waters such as large rivers, lakes, reservoirs, and estuaries. The reviews in this collection focus on the types of waters whose protections under the U.S. Clean Water Act have been called into question by U.S. Supreme Court cases. We synthesize 40+ years of research on longitudinal, lateral, and vertical fluxes of energy, material, and biota between aquatic ecosystems included within the Act's frame of reference. Many questions about the roles of streams and wetlands in sustaining downstream water integrity can be answered from currently available literature, and emerging research is rapidly closing data gaps with exciting new insights into aquatic connectivity and function at local, watershed, and regional scales. Synthesis of foundational and emerging research is needed to support science‐based efforts to provide safe, reliable sources of fresh water for present and future generations.

Transport logistics in pollen tubes.

PubMed

Chebli, Youssef; Kroeger, Jens; Geitmann, Anja

2013-07-01

Cellular organelles move within the cellular volume and the effect of the resulting drag forces on the liquid causes bulk movement in the cytosol. The movement of both organelles and cytosol leads to an overall motion pattern called cytoplasmic streaming or cyclosis. This streaming enables the active and passive transport of molecules and organelles between cellular compartments. Furthermore, the fusion and budding of vesicles with and from the plasma membrane (exo/endocytosis) allow for transport of material between the inside and the outside of the cell. In the pollen tube, cytoplasmic streaming and exo/endocytosis are very active and fulfill several different functions. In this review, we focus on the logistics of intracellular motion and transport processes as well as their biophysical underpinnings. We discuss various modeling attempts that have been performed to understand both long-distance shuttling and short-distance targeting of organelles. We show how the combination of mechanical and mathematical modeling with cell biological approaches has contributed to our understanding of intracellular transport logistics.

Modeling of Floating Time Domain Electromagnetic Method to Detect Dissolved Sediment

NASA Astrophysics Data System (ADS)

Nurjanah, Siti; Widodo

2017-04-01

In hydrology context, sediment can be interpreted as inorganic and organic material that is transported by, suspended in, or deposited by streams. It is important to know the function of soil, stream discharge, land-cover features, weather conditions and land-use activities. Sediment load carried by streams and rivers can be composed either of fine materials, mostly silts, and clays, or coarse materials such as sand. One product of sediment is dissolved load consists of indistinct material in solution moving downstream. It is produced by chemical weathering processes and does not move out of the water. To investigate the dissolved sediment, we have applied the floating of Time Domain Electromagnetic (TDEM) method. The acquisition of TDEM data has been performed use tires and small ship as innovation measurements. The calculated data model using Occam and Marquardt Algorithms. The responses of data show the sedimentation has less resistive compare the surrounding structures. This innovation is very helpful to know the environmental condition, especially in the water.

Functional ecomorphology: Feedbacks between form and function in fluvial landscape ecosystems

NASA Astrophysics Data System (ADS)

Fisher, Stuart G.; Heffernan, James B.; Sponseller, Ryan A.; Welter, Jill R.

2007-09-01

The relationship between form and function has been a central organizing principle in biology throughout its history as a formal science. This concept has been relevant from molecules to organisms but loses meaning at population and community levels where study targets are abstract collectives and assemblages. Ecosystems include organisms and abiotic factors but ecosystem ecology too has developed until recently without a strong spatially explicit reference. Landscape ecology provides an opportunity to once again anneal form and function and to consider reciprocal causation between them. This ecomorphologic view can be applied at a variety of ecologically relevant scales and consists of an investigation of how geomorphology provides a structural template that shapes, and is shaped by ecological processes. Running water ecosystems illustrate several principles governing the interaction of landscape form and ecological function subsumed by the concept of "Functional Ecomorphology". Particularly lucrative are ecosystem-level interactions between geologic form and biogeochemical processes integrated by hydrologic flowpaths. While the utility of a flowpath-based approach is most apparent in streams, spatially explicit biogeochemical processing pervades all landscapes and may be of general ecological application.

Oxytocin differentially alters resting state functional connectivity between amygdala subregions and emotional control networks: Inverse correlation with depressive traits.

PubMed

Eckstein, Monika; Markett, Sebastian; Kendrick, Keith M; Ditzen, Beate; Liu, Fang; Hurlemann, Rene; Becker, Benjamin

2017-04-01

The hypothalamic neuropeptide oxytocin (OT) has received increasing attention for its role in modulating social-emotional processes across species. Previous studies on using intranasal-OT in humans point to a crucial engagement of the amygdala in the observed neuromodulatory effects of OT under task and rest conditions. However, the amygdala is not a single homogenous structure, but rather a set of structurally and functionally heterogeneous nuclei that show distinct patterns of connectivity with limbic and frontal emotion-processing regions. To determine potential differential effects of OT on functional connectivity of the amygdala subregions, 79 male participants underwent resting-state fMRI following randomized intranasal-OT or placebo administration. In line with previous studies OT increased the connectivity of the total amygdala with dorso-medial prefrontal regions engaged in emotion regulation. In addition, OT enhanced coupling of the total amygdala with cerebellar regions. Importantly, OT differentially altered the connectivity of amygdala subregions with distinct up-stream cortical nodes, particularly prefrontal/parietal, and cerebellar down-stream regions. OT-induced increased connectivity with cerebellar regions were largely driven by effects on the centromedial and basolateral subregions, whereas increased connectivity with prefrontal regions were largely mediated by right superficial and basolateral subregions. OT decreased connectivity of the centromedial subregions with core hubs of the emotional face processing network in temporal, occipital and parietal regions. Preliminary findings suggest that effects on the superficial amygdala-prefrontal pathway were inversely associated with levels of subclinical depression, possibly indicating that OT modulation may be blunted in the context of increased pathological load. Together, the present findings suggest a subregional-specific modulatory role of OT on amygdala-centered emotion processing networks in humans. Copyright © 2017 Elsevier Inc. All rights reserved.

40 CFR 63.11940 - What continuous monitoring requirements must I meet for control devices required to install CPMS...

Code of Federal Regulations, 2012 CFR

2012-07-01

... consistent with the manufacturer's recommendations within 15 days or by the next time any process vent stream... the manufacturer's recommendations within 15 days or by the next time any process vent stream is...) Determine gas stream flow using the design blower capacity, with appropriate adjustments for pressure drop...

Carbon dioxide removal process

DOEpatents

Baker, Richard W.; Da Costa, Andre R.; Lokhandwala, Kaaeid A.

2003-11-18

A process and apparatus for separating carbon dioxide from gas, especially natural gas, that also contains C.sub.3+ hydrocarbons. The invention uses two or three membrane separation steps, optionally in conjunction with cooling/condensation under pressure, to yield a lighter, sweeter product natural gas stream, and/or a carbon dioxide stream of reinjection quality and/or a natural gas liquids (NGL) stream.

Interaction of Substrate and Nutrient Availability on wood Biofilm Processes in Streams

Treesearch

Jennifer L. Tank; J.R. Webster

1998-01-01

We examined the effect of decomposing leaf litter and dissolved inorganic nutrients on the heterotrophic biofilm of submerged wood in streams with and without leaves. Leaf litter was excluded from one headwater stream in August 1993 at Coweeta Hydrologic Laboratory in the southern Appalachian Mountains. We compared microbial processes on wood in the litter-excluded...

Ventral and Dorsal Pathways Relate Differently to Visual Awareness of Body Postures under Continuous Flash Suppression

PubMed Central

Goebel, Rainer

2018-01-01

Abstract Visual perception includes ventral and dorsal stream processes. However, it is still unclear whether the former is predominantly related to conscious and the latter to nonconscious visual perception as argued in the literature. In this study upright and inverted body postures were rendered either visible or invisible under continuous flash suppression (CFS), while brain activity of human participants was measured with functional MRI (fMRI). Activity in the ventral body-sensitive areas was higher during visible conditions. In comparison, activity in the posterior part of the bilateral intraparietal sulcus (IPS) showed a significant interaction of stimulus orientation and visibility. Our results provide evidence that dorsal stream areas are less associated with visual awareness. PMID:29445766

Liquid additives for particulate emissions control

DOEpatents

Durham, Michael Dean; Schlager, Richard John; Ebner, Timothy George; Stewart, Robin Michele; Hyatt, David E.; Bustard, Cynthia Jean; Sjostrom, Sharon

1999-01-01

The present invention discloses a process for removing undesired particles from a gas stream including the steps of contacting a composition containing an adhesive with the gas stream; collecting the undesired particles and adhesive on a collection surface to form an aggregate comprising the adhesive and undesired particles on the collection surface; and removing the agglomerate from the collection zone. The composition may then be atomized and injected into the gas stream. The composition may include a liquid that vaporizes in the gas stream. After the liquid vaporizes, adhesive particles are entrained in the gas stream. The process may be applied to electrostatic precipitators and filtration systems to improve undesired particle collection efficiency.

Climatic and Landscape Controls on Storage Capacity of Urban Stormwater Control Measures (SCMs): Implications for Stormwater-Stream Connectivity

NASA Astrophysics Data System (ADS)

Fanelli, R. M.; Prestegaard, K. L.; Palmer, M.

2015-12-01

Urbanization alters watershed hydrological processes; impervious surfaces increase runoff generation, while storm sewer networks increase connectivity between runoff sources and streams. Stormwater control measures (SCMs) that enhance stormwater infiltration have been proposed to mitigate these effects by functioning as stormwater sinks. Regenerative stormwater conveyances structures (RSCs) are an example of infiltration-based SCMs that are placed between storm sewer outfalls and perennial stream networks. Given their location, RSCs act as critical nodes that regulate stormwater-stream connectivity. Therefore, the storage capacity of a RSC structure may exert a major control on the frequency, duration, and magnitude of these connections. This project examined both hydrogeological and hydro-climatic factors that could influence storage capacity of RSC structures. We selected three headwater (5-48 ha) urban watersheds near Annapolis, Maryland, USA. Each watershed is drained by first-order perennial streams and has been implemented with a RSC structure. We conducted high-frequency precipitation and stream stage monitoring below the outlet of each RSC structure for a 1-year period. We also instrumented one of the RSC structures with groundwater wells to monitor changes in subsurface storage over time. Using these data, we 1) identified rainfall thresholds for RSC storage capacity exceedance; 2) quantified the frequency and duration of connectivity when the storage capacity of each RSC was exceeded; and 3) evaluated both event-scale and seasonal changes in groundwater levels within the RSC structure. Precipitation characteristics and antecedent precipitation indices influenced the frequency and duration of stormwater-stream connections. We hypothesize both infiltration limitations and storage limitations of the RSCs contributed to the temporal patterns we observed in stormwater-stream connectivity. We also observed reduced storage potential as contributing area and percent impervious cover increased. Overall, the efficacy of urban SCMs for mitigating the impacts of urbanization and reducing stormwater-stream connectivity is dependent on both climate and the landscape context in which they are placed.

Continuous online Fourier transform infrared (FT-IR) spectrometry analysis of hydrogen chloride (HCl), carbon dioxide (CO2), and water (H2O) in nitrogen-rich and ethylene-rich streams.

PubMed

Stephenson, Serena; Pollard, Maria; Boit, Kipchirchir

2013-09-01

The prevalence of optical spectroscopy techniques being applied to the online analysis of continuous processes has increased in the past couple of decades. The ability to continuously "watch" changing stream compositions as operating conditions change has proven invaluable to pilot and world-scale manufacturing in the chemical and petrochemical industries. Presented here is an application requiring continuous monitoring of parts per million (ppm) by weight levels of hydrogen chloride (HCl), water (H2O), and carbon dioxide (CO2) in two gas-phase streams, one nitrogen-rich and one ethylene-rich. Because ethylene has strong mid-infrared (IR) absorption, building an IR method capable of quantifying HCl, H2O, and CO2 posed some challenges. A long-path (5.11m) Fourier transform infrared (FT-IR) spectrometer was used in the mid-infrared region between 1800 and 5000 cm(-1), with a 1 cm(-1) resolution and a 10 s spectral update time. Sample cell temperature and pressure were controlled and measured to minimize measurement variability. Models using a modified classical least squares method were developed and validated first in the laboratory and then using the process stream. Analytical models and process sampling conditions were adjusted to minimize interference of ethylene in the ethylene-rich stream. The predictive capabilities of the measurements were ±0.5 ppm for CO2 in either stream; ±1.1 and ±1.3 ppm for H2O in the nitrogen-rich and ethylene-rich streams, respectively; and ±1.0 and ±2.4 ppm for HCl in the nitrogen-rich and ethylene-rich streams, respectively. Continuous operation of the instrument in the process stream was demonstrated using an automated stream switching sample system set to 10 min intervals. Response time for all components of interest was sufficient to acquire representative stream composition data. This setup provides useful insight into the process for troubleshooting and optimizing plant operating conditions.

Secondary production of benthic insects in three cold-desert streams

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

Gaines, W.L.

1987-07-01

Aquatic insect production was studied in three cold-desert streams in eastern Washington (Douglas Creek, Snively Springs, and Rattlesnake Springs). The size-frequency method was applied to individual taxa to estimate total insect production. production was also assessed for functional groups and trophic levels in each stream. Optioservus sp. (riffle beetles) and Baetis sp. (mayflies) accounted for 72% of the total insect numbers and 50% of the total biomass in Douglas Creek. Baetis sp. accounted for 42% of the total insect numbers and 25% of the total biomass in Snively Springs. Simulium sp. (blackflies) and Baetis sp. comprised 74% of the totalmore » insect numbers and 55% of the total biomass in Rattlesnake Springs. Grazer-scrapers (49%) and collectors (48%) were the most abundant functional groups in Douglas Creek. Collectors were the most abundant functional group in Snively Springs and Rattlesnake Springs. Herbivores and detritivores were the most abundant trophic level in Snively Springs and Rattlesnake Springs. Dipterans (midges and blackflies) were the most productive taxa within the study streams, accounting for 40% to 70% of the total community production. Production by collectors and detritivores was the highest of all functional groups and trophic levels in all study streams.« less

Instrumental methods of analysis of sulfur compounds in synfuel process streams. Quarterly technical progress report, July-September 1984

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

Jordan, J.; Talbott, J.

1984-01-01

Task 1. Methods development for the speciation of the polysulfides. Work on this task has been completed in December 1983 and reported accordingly in DOE/PC/40783-T13. Task 2. Methods development for the speciation of dithionite and polythionates. Work on Task 2 has been completed in June 1984 and has been reported accordingly in DOE/PC/40783-T15. Task 3. Total accounting of the sulfur balance in representative samples of synfuel process streams. A systematic and critical comparison of results, obtained in the analysis of sulfur moieties in representative samples of coal conversion process streams, revealed the following general trends. (a) In specimens of highmore » pH (9-10) and low redox potential (-0.3 to -0.4 volt versus NHE) sulfidic and polysulfidic sulfur moieties predominate. (b) In process streams of lower pH and more positive redox potential, higher oxidation states of sulfur (notably sulfate) account for most of the total sulfur present. (c) Oxidative wastewater treatment procedures by the PETC stripping process convert lower oxidation states of sulfur into thiosulfate and sulfate. In this context, remarkable similarities were observed between liquefaction and gasification process streams. However, the thiocyanate present in samples from the Grand Forks gasifier were impervious to the PETC stripping process. (d) Total sulfur contaminant levels in coal conversion process stream wastewater samples are primarily determined by the abundance of sulfur in the coal used as starting material than by the nature of the conversion process (liquefaction or gasification). 13 references.« less

Alpha-band rhythm modulation under the condition of subliminal face presentation: MEG study.

PubMed

Sakuraba, Satoshi; Kobayashi, Hana; Sakai, Shinya; Yokosawa, Koichi

2013-01-01

The human brain has two streams to process visual information: a dorsal stream and a ventral stream. Negative potential N170 or its magnetic counterpart M170 is known as the face-specific signal originating from the ventral stream. It is possible to present a visual image unconsciously by using continuous flash suppression (CFS), which is a visual masking technique adopting binocular rivalry. In this work, magnetoencephalograms were recorded during presentation of the three invisible images: face images, which are processed by the ventral stream; tool images, which could be processed by the dorsal stream, and a blank image. Alpha-band activities detected by sensors that are sensitive to M170 were compared. The alpha-band rhythm was suppressed more during presentation of face images than during presentation of the blank image (p=.028). The suppression remained for about 1 s after ending presentations. However, no significant difference was observed between tool and other images. These results suggest that alpha-band rhythm can be modulated also by unconscious visual images.

StreamQRE: Modular Specification and Efficient Evaluation of Quantitative Queries over Streaming Data.

PubMed

Mamouras, Konstantinos; Raghothaman, Mukund; Alur, Rajeev; Ives, Zachary G; Khanna, Sanjeev

2017-06-01

Real-time decision making in emerging IoT applications typically relies on computing quantitative summaries of large data streams in an efficient and incremental manner. To simplify the task of programming the desired logic, we propose StreamQRE, which provides natural and high-level constructs for processing streaming data. Our language has a novel integration of linguistic constructs from two distinct programming paradigms: streaming extensions of relational query languages and quantitative extensions of regular expressions. The former allows the programmer to employ relational constructs to partition the input data by keys and to integrate data streams from different sources, while the latter can be used to exploit the logical hierarchy in the input stream for modular specifications. We first present the core language with a small set of combinators, formal semantics, and a decidable type system. We then show how to express a number of common patterns with illustrative examples. Our compilation algorithm translates the high-level query into a streaming algorithm with precise complexity bounds on per-item processing time and total memory footprint. We also show how to integrate approximation algorithms into our framework. We report on an implementation in Java, and evaluate it with respect to existing high-performance engines for processing streaming data. Our experimental evaluation shows that (1) StreamQRE allows more natural and succinct specification of queries compared to existing frameworks, (2) the throughput of our implementation is higher than comparable systems (for example, two-to-four times greater than RxJava), and (3) the approximation algorithms supported by our implementation can lead to substantial memory savings.

StreamQRE: Modular Specification and Efficient Evaluation of Quantitative Queries over Streaming Data*

PubMed Central

Mamouras, Konstantinos; Raghothaman, Mukund; Alur, Rajeev; Ives, Zachary G.; Khanna, Sanjeev

2017-01-01

Real-time decision making in emerging IoT applications typically relies on computing quantitative summaries of large data streams in an efficient and incremental manner. To simplify the task of programming the desired logic, we propose StreamQRE, which provides natural and high-level constructs for processing streaming data. Our language has a novel integration of linguistic constructs from two distinct programming paradigms: streaming extensions of relational query languages and quantitative extensions of regular expressions. The former allows the programmer to employ relational constructs to partition the input data by keys and to integrate data streams from different sources, while the latter can be used to exploit the logical hierarchy in the input stream for modular specifications. We first present the core language with a small set of combinators, formal semantics, and a decidable type system. We then show how to express a number of common patterns with illustrative examples. Our compilation algorithm translates the high-level query into a streaming algorithm with precise complexity bounds on per-item processing time and total memory footprint. We also show how to integrate approximation algorithms into our framework. We report on an implementation in Java, and evaluate it with respect to existing high-performance engines for processing streaming data. Our experimental evaluation shows that (1) StreamQRE allows more natural and succinct specification of queries compared to existing frameworks, (2) the throughput of our implementation is higher than comparable systems (for example, two-to-four times greater than RxJava), and (3) the approximation algorithms supported by our implementation can lead to substantial memory savings. PMID:29151821

Landscape characteristics of a stream and wetland mitigation banking program.

PubMed

BenDor, Todd; Sholtes, Joel; Doyle, Martin W

2009-12-01

In the United States, stream restoration is an increasing part of environmental and land management programs, particularly under the auspices of compensatory mitigation regulations. Markets and regulations surrounding stream mitigation are beginning to mirror those of the well-established wetland mitigation industry. Recent studies have shown that wetland mitigation programs commonly shift wetlands across space from urban to rural areas, thereby changing the functional characteristics and benefits of wetlands in the landscape. However, it is not yet known if stream mitigation mirrors this behavior, and if so, what effects this may have on landscape-scale ecological and hydrological processes. This project addresses three primary research questions. (1) What are the spatial relationships between stream and wetland impact and compensation sites as a result of regulations requiring stream and wetland mitigation in the State of North Carolina? (2) How do stream impacts come about due to the actions of different types of developers, and how do the characteristics of impacts sites compare with compensation sites? (3) To what extent does stream compensation relocate high-quality streams within the river network, and how does this affect localized (intrawatershed) loss or gain of aquatic resources? Using geospatial data collected from the North Carolina Division of Water Quality and the Army Corps of Engineers' Wilmington District, we analyzed the behavior of the North Carolina Ecosystem Enhancement Program in providing stream and wetland mitigation for the State of North Carolina. Our results suggest that this program provides mitigation (1) in different ways for different types of permittees; (2) at great distances (both Euclidean and within the stream network) from original impacts; (3) in significantly different places than impacts within watersheds; and (4) in many cases, in different watersheds from original impacts. Our analysis also reveals problems with regulator data collection, storage, and quality control. These results have significant implications given new federal requirements for ecological consistency within mitigation programs. Our results also indicate some of the landscape-scale implications of using market-based approaches to ecological restoration in general.

Remembering the Important Things: Semantic Importance in Stream Reasoning

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

Yan, Rui; Greaves, Mark T.; Smith, William P.

Reasoning and querying over data streams rely on the abil- ity to deliver a sequence of stream snapshots to the processing algo- rithms. These snapshots are typically provided using windows as views into streams and associated window management strategies. Generally, the goal of any window management strategy is to preserve the most im- portant data in the current window and preferentially evict the rest, so that the retained data can continue to be exploited. A simple timestamp- based strategy is rst-in-rst-out (FIFO), in which items are replaced in strict order of arrival. All timestamp-based strategies implicitly assume that a temporalmore » ordering reliably re ects importance to the processing task at hand, and thus that window management using timestamps will maximize the ability of the processing algorithms to deliver accurate interpretations of the stream. In this work, we explore a general no- tion of semantic importance that can be used for window management for streams of RDF data using semantically-aware processing algorithms like deduction or semantic query. Semantic importance exploits the infor- mation carried in RDF and surrounding ontologies for ranking window data in terms of its likely contribution to the processing algorithms. We explore the general semantic categories of query contribution, prove- nance, and trustworthiness, as well as the contribution of domain-specic ontologies. We describe how these categories behave using several con- crete examples. Finally, we consider how a stream window management strategy based on semantic importance could improve overall processing performance, especially as available window sizes decrease.« less

MODELING STREAM-AQUIFIER INTERACTIONS WITH LINEAR RESPONSE FUNCTIONS

EPA Science Inventory

The problem of stream-aquifer interactions is pertinent to conjunctive-use management of water resources and riparian zone hydrology. Closed form solutions are derived for stream-aquifer interactions in rates and volumes expressed as convolution integrals of impulse response and ...

Stream computing for biomedical signal processing: A QRS complex detection case-study.

PubMed

Murphy, B M; O'Driscoll, C; Boylan, G B; Lightbody, G; Marnane, W P

2015-01-01

Recent developments in "Big Data" have brought significant gains in the ability to process large amounts of data on commodity server hardware. Stream computing is a relatively new paradigm in this area, addressing the need to process data in real time with very low latency. While this approach has been developed for dealing with large scale data from the world of business, security and finance, there is a natural overlap with clinical needs for physiological signal processing. In this work we present a case study of streams processing applied to a typical physiological signal processing problem: QRS detection from ECG data.

The paradox of cooling streams in a warming world: regional climate trends do not parallel variable local trends in stream temperature in the Pacific continental United States

Treesearch

Ivan Arismendi; Sherri L. Johnson; Jason B. Dunham; Roy Haggerty

2012-01-01

Temperature is a fundamentally important driver of ecosystem processes in streams. Recent warming of terrestrial climates around the globe has motivated concern about consequent increases in stream temperature. More specifically, observed trends of increasing air temperature and declining stream flow are widely believed to result in corresponding increases in stream...

Species replacement by a nonnative salmonid alters ecosystem function by reducing prey subsidies that support riparian spiders

USGS Publications Warehouse

Benjamin, J.R.; Fausch, K.D.; Baxter, C.V.

2011-01-01

Replacement of a native species by a nonnative can have strong effects on ecosystem function, such as altering nutrient cycling or disturbance frequency. Replacements may cause shifts in ecosystem function because nonnatives establish at different biomass, or because they differ from native species in traits like foraging behavior. However, no studies have compared effects of wholesale replacement of a native by a nonnative species on subsidies that support consumers in adjacent habitats, nor quantified the magnitude of these effects. We examined whether streams invaded by nonnative brook trout (Salvelinus fontinalis) in two regions of the Rocky Mountains, USA, produced fewer emerging adult aquatic insects compared to paired streams with native cutthroat trout (Oncorhynchus clarkii), and whether riparian spiders that depend on these prey were less abundant along streams with lower total insect emergence. As predicted, emergence density was 36% lower from streams with the nonnative fish. Biomass of brook trout was higher than the cutthroat trout they replaced, but even after accounting for this difference, emergence was 24% lower from brook trout streams. More riparian spiders were counted along streams with greater total emergence across the water surface. Based on these results, we predicted that brook trout replacement would result in 6-20% fewer spiders in the two regions. When brook trout replace cutthroat trout, they reduce cross-habitat resource subsidies and alter ecosystem function in stream-riparian food webs, not only owing to increased biomass but also because traits apparently differ from native cutthroat trout. ?? 2011 Springer-Verlag.

Local Circuits of V1 Layer 4B Neurons Projecting to V2 Thick Stripes Define Distinct Cell Classes and Avoid Cytochrome Oxidase Blobs

PubMed Central

Yarch, Jeff; Federer, Frederick

2017-01-01

Decades of anatomical studies on the primate primary visual cortex (V1) have led to a detailed diagram of V1 intrinsic circuitry, but this diagram lacks information about the output targets of V1 cells. Understanding how V1 local processing relates to downstream processing requires identification of neuronal populations defined by their output targets. In primates, V1 layers (L)2/3 and 4B send segregated projections to distinct cytochrome oxidase (CO) stripes in area V2: neurons in CO blob columns project to thin stripes while neurons outside blob columns project to thick and pale stripes, suggesting functional specialization of V1-to-V2 CO streams. However, the conventional diagram of V1 shows all L4B neurons, regardless of their soma location in blob or interblob columns, as projecting selectively to CO blobs in L2/3, suggesting convergence of blob/interblob information in L2/3 blobs and, possibly, some V2 stripes. However, it is unclear whether all L4B projection neurons show similar local circuitries. Using viral-mediated circuit tracing, we have identified the local circuits of L4B neurons projecting to V2 thick stripes in macaque. Consistent with previous studies, we found the somata of this L4B subpopulation to reside predominantly outside blob columns; however, unlike previous descriptions of local L4B circuits, these cells consistently projected outside CO blob columns in all layers. Thus, the local circuits of these L4B output neurons, just like their extrinsic projections to V2, preserve CO streams. Moreover, the intra-V1 laminar patterns of axonal projections identify two distinct neuron classes within this L4B subpopulation, including a rare novel neuron type, suggestive of two functionally specialized output channels. SIGNIFICANCE STATEMENT Conventional diagrams of primate primary visual cortex (V1) depict neuronal connections within and between different V1 layers, but lack information about the cells' downstream targets. This information is critical to understanding how local processing in V1 relates to downstream processing. We have identified the local circuits of a population of cells in V1 layer (L)4B that project to area V2. These cells' local circuits differ from classical descriptions of L4B circuits in both the laminar and functional compartments targeted by their axons, and identify two neuron classes. Our results demonstrate that both local intra-V1 and extrinsic V1-to-V2 connections of L4B neurons preserve CO-stream segregation, suggesting that across-stream integration occurs downstream of V1, and that output targets dictate local V1 circuitry. PMID:28077720

High temperature methods for forming oxidizer fuel

DOEpatents

Bravo, Jose Luis [Houston, TX

2011-01-11

A method of treating a formation fluid includes providing formation fluid from a subsurface in situ heat treatment process. The formation fluid is separated to produce a liquid stream and a first gas stream. The first gas stream includes carbon dioxide, hydrogen sulfide, hydrocarbons, hydrogen or mixtures thereof. Molecular oxygen is separated from air to form a molecular oxygen stream comprising molecular oxygen. The first gas stream is combined with the molecular oxygen stream to form a combined stream comprising molecular oxygen and the first gas stream. The combined stream is provided to one or more downhole burners.

Integration and segregation in auditory streaming

NASA Astrophysics Data System (ADS)

Almonte, Felix; Jirsa, Viktor K.; Large, Edward W.; Tuller, Betty

2005-12-01

We aim to capture the perceptual dynamics of auditory streaming using a neurally inspired model of auditory processing. Traditional approaches view streaming as a competition of streams, realized within a tonotopically organized neural network. In contrast, we view streaming to be a dynamic integration process which resides at locations other than the sensory specific neural subsystems. This process finds its realization in the synchronization of neural ensembles or in the existence of informational convergence zones. Our approach uses two interacting dynamical systems, in which the first system responds to incoming acoustic stimuli and transforms them into a spatiotemporal neural field dynamics. The second system is a classification system coupled to the neural field and evolves to a stationary state. These states are identified with a single perceptual stream or multiple streams. Several results in human perception are modelled including temporal coherence and fission boundaries [L.P.A.S. van Noorden, Temporal coherence in the perception of tone sequences, Ph.D. Thesis, Eindhoven University of Technology, The Netherlands, 1975], and crossing of motions [A.S. Bregman, Auditory Scene Analysis: The Perceptual Organization of Sound, MIT Press, 1990]. Our model predicts phenomena such as the existence of two streams with the same pitch, which cannot be explained by the traditional stream competition models. An experimental study is performed to provide proof of existence of this phenomenon. The model elucidates possible mechanisms that may underlie perceptual phenomena.

Coupled stream and population dynamics: Modeling the role beaver (Castor canadensis) play in generating juvenile steelhead (Oncorhynchus mykiss) habitat

NASA Astrophysics Data System (ADS)

Jordan, C.; Bouwes, N.; Wheaton, J. M.; Pollock, M.

2013-12-01

Over the past several centuries, the population of North American Beaver has been dramatically reduced through fur trapping. As a result, the geomorphic impacts long-term beaver occupancy and activity can have on fluvial systems have been lost, both from the landscape and from our collective memory such that physical and biological models of floodplain system function neither consider nor have the capacity to incorporate the role beaver can play in structuring the dynamics of streams. Concomitant with the decline in beaver populations was an increasing pressure on streams and floodplains through human activity, placing numerous species of stream rearing fishes in peril, most notably the ESA listing of trout and salmon populations across the entirety of the Western US. The rehabilitation of stream systems is seen as one of the primary means by which population and ecosystem recovery can be achieved, yet the methods of stream rehabilitation are applied almost exclusively with the expected outcome of a static idealized stream planform, occasionally with an acknowledgement of restoring processes rather than form and only rarely with the goal of a beaver dominated riverscape. We have constructed an individual based model of trout and beaver populations that allows the exploration of fish population dynamics as a function of stream habitat quality and quantity. We based the simulation tool on Bridge Creek (John Day River basin, Oregon) where we have implemented a large-scale restoration experiment using wooden posts to provide beavers with stable platforms for dam building and to simulate the dams themselves. Extensive monitoring captured geomorphic and riparian changes, as well as fish and beaver population responses; information we use to parameterize the model as to the geomorphic and fish response to dam building beavers. In the simulation environment, stream habitat quality and quantity can be manipulated directly through rehabilitation actions and indirectly through the dynamics of the co-occurring beaver population. The model allowed to us to ask questions critical for designing restoration strategies based on dam building beaver activity, such as what beaver population growth rate is required to develop and maintain floodplain connectivity in an incised system, or what beaver population size is required to increase juvenile steelhead production? The model was sensitive to several variables including beaver colony size, dams and colony dynamics and site fidelity, and thus highlights further research needs to fill critical information gaps.

Ice flow in the Weddell Sea sector of West Antarctica as elucidated by radar-imaged internal layering

NASA Astrophysics Data System (ADS)

Bingham, R. G.; Rippin, D. M.; Karlsson, N. B.; Corr, H.; Ferraccioli, F.; Jordan, T. A.; Le Brocq, A.; Ross, N.; Wright, A.; Siegert, M. J.

2012-12-01

Radio-echo sounding (RES) across polar ice sheets reveals extensive, isochronous internal layers, whose stratigraphy, and especially their degree of continuity over multi-km distances, can inform us about both present ice flow and past ice-flow histories. Here, we bring together for the first time two recent advances in this field of cryospheric remote sensing to analyse ice flow into the Weddell Sea sector of West Antarctica. Firstly, we have developed a new quantitative routine for analysing the continuity of internal layers obtained over large areas of ice by airborne RES surveys - we term this routine the "Internal-Layering Continuity-Index (ILCI)". Secondly, in the austral season 2010-11 we acquired, by airborne RES survey, the first comprehensive dataset of deep internal layering across Institute and Möller Ice Streams, two of the more significant feeders of ice into the Filchner-Ronne Ice Shelf. Applying the ILCI to SAR-processed (migrated) RES profiles across Institute Ice Stream's catchment reveals two contrasting regions of internal-layering continuity behaviour. In the western portion of the catchment, where ice-stream tributaries incise deeply through the Ellsworth Subglacial Highlands, the continuity of internal layers is most disrupted across the present ice streams. We therefore interpret the ice-flow configuration in this western region as predominantly spatially stable over the lifetime of the ice. Further east, towards Möller Ice Stream, and towards the interior of the ice sheet, the ILCI does not closely match the present ice flow configuration, while across most of present-day Möller Ice Stream itself, the continuity of internal layers is generally low. We propose that the variation in continuity of internal layering across eastern Institute Ice Stream and the neighbouring Möller results primarily from two factors. Firstly, the noncorrespondence of some inland tributaries with internal-layering continuity acts as evidence for past spatial migration of those tributaries, with likely consequences for the relative positions of Institute and Möller Ice Streams over recent history. Secondly, the subglacial roughness, in part a function of the underlying geology across the region, imposes a strong influence on the continuity of the overlying deep internal layers, though whether it controls, or is a function of, ice flow, remains undetermined. We conclude that in the subglacially mountainous Ellsworth Subglacial Highlands sector, there is long-term stability in the spatial configuration of ice flow, but that elsewhere across Insitute and Möller Ice Streams, the ice-flow configuration has the potential to switch.

Radar-imaged internal layering in the Weddell Sea sector of West Antarctica

NASA Astrophysics Data System (ADS)

Bingham, Robert G.; Rippin, David M.; Karlsson, Nanna B.; Corr, Hugh F. J.; Ferraccioli, Fausto; Jordan, Tom A.; Le Brocq, Anne M.; Ross, Neil; Wright, Andrew P.; Siegert, Martin J.

2013-04-01

Radio-echo sounding (RES) across polar ice sheets reveals extensive, isochronous internal layers, whose stratigraphy, and especially their degree of continuity over multi-km distances, can inform us about both present ice flow and past ice-flow histories. Here, we bring together for the first time two recent advances in this field of cryospheric remote sensing to analyse ice flow into the Weddell Sea sector of West Antarctica. Firstly, we have developed a new quantitative routine for analysing the continuity of internal layers obtained over large areas of ice by airborne RES surveys - we term this routine the "Internal-Layering Continuity-Index (ILCI)". Secondly, in the austral season 2010-11 we acquired, by airborne RES survey, the first comprehensive dataset of deep internal layering across Institute and Möller Ice Streams, two of the more significant feeders of ice into the Filchner-Ronne Ice Shelf. Applying the ILCI to SAR-processed (migrated) RES profiles across Institute Ice Stream's catchment reveals two contrasting regions of internal-layering continuity behaviour. In the western portion of the catchment, where ice-stream tributaries incise deeply through the Ellsworth Subglacial Highlands, the continuity of internal layers is most disrupted across the present ice streams. We therefore interpret the ice-flow configuration in this western region as predominantly spatially stable over the lifetime of the ice. Further east, towards Möller Ice Stream, and towards the interior of the ice sheet, the ILCI does not closely match the present ice flow configuration, while across most of present-day Möller Ice Stream itself, the continuity of internal layers is generally low. We propose that the variation in continuity of internal layering across eastern Institute Ice Stream and the neighbouring Möller results primarily from two factors. Firstly, the noncorrespondence of some inland tributaries with internal-layering continuity acts as evidence for past spatial migration of those tributaries, with likely consequences for the relative positions of Institute and Möller Ice Streams over recent history. Secondly, the subglacial roughness, in part a function of the underlying geology across the region, imposes a strong influence on the continuity of the overlying deep internal layers, though whether it controls, or is a function of, ice flow, remains undetermined. We conclude that in the subglacially mountainous Ellsworth Subglacial Highlands sector, there is long-term stability in the spatial configuration of ice flow, but that elsewhere across Insitute and Möller Ice Streams, the ice-flow configuration is not stable.

Aquifer response to stream-stage and recharge variations. I. Analytical step-response functions

USGS Publications Warehouse

Moench, A.F.; Barlow, P.M.

2000-01-01

Laplace transform step-response functions are presented for various homogeneous confined and leaky aquifer types and for anisotropic, homogeneous unconfined aquifers interacting with perennial streams. Flow is one-dimensional, perpendicular to the stream in the confined and leaky aquifers, and two-dimensional in a plane perpendicular to the stream in the water-table aquifers. The stream is assumed to penetrate the full thickness of the aquifer. The aquifers may be semi-infinite or finite in width and may or may not be bounded at the stream by a semipervious streambank. The solutions are presented in a unified manner so that mathematical relations among the various aquifer configurations are clearly demonstrated. The Laplace transform solutions are inverted numerically to obtain the real-time step-response functions for use in the convolution (or superposition) integral. To maintain linearity in the case of unconfined aquifers, fluctuations in the elevation of the water table are assumed to be small relative to the saturated thickness, and vertical flow into or out of the zone above the water table is assumed to occur instantaneously. Effects of hysteresis in the moisture distribution above the water table are therefore neglected. Graphical comparisons of the new solutions are made with known closed-form solutions.Laplace transform step-response functions are presented for various homogeneous confined and leaky aquifer types and for anisotropic, homogeneous unconfined aquifers interacting with perennial streams. Flow is one-dimensional, perpendicular to the stream in the confined and leaky aquifers, and two-dimensional in a plane perpendicular to the stream in the water-table aquifers. The stream is assumed to penetrate the full thickness of the aquifer. The aquifers may be semi-infinite or finite in width and may or may not be bounded at the stream by a semipervious streambank. The solutions are presented in a unified manner so that mathematical relations among the various aquifer configurations are clearly demonstrated. The Laplace transform solutions are inverted numerically to obtain the real-time step-response functions for use in the convolution (or superposition) integral. To maintain linearity in the case of unconfined aquifers, fluctuations in the elevation of the water table are assumed to be small relative to the saturated thickness, and vertical flow into or out of the zone above the water table is assumed to occur instantaneously. Effects of hysteresis in the moisture distribution above the water table are therefore neglected. Graphical comparisons of the new solutions are made with known closed-form solutions.

Process for the displacement of cyanide ions from metal-cyanide complexes

DOEpatents

Smith, Barbara F.; Robinson, Thomas W.

1997-01-01

The present invention relates to water-soluble polymers and the use of such water-soluble polymers in a process for the displacement of the cyanide ions from the metal ions within metal-cyanide complexes. The process waste streams can include metal-cyanide containing electroplating waste streams, mining leach waste streams, mineral processing waste streams, and related metal-cyanide containing waste streams. The metal ions of interest are metals that give very strong complexes with cyanide, mostly iron, nickel, and copper. The physical separation of the water-soluble polymer-metal complex from the cyanide ions can be accomplished through the use of ultrafiltration. Once the metal-cyanide complex is disrupted, the freed cyanide ions can be recovered for reuse or destroyed using available oxidative processes rendering the cyanide nonhazardous. The metal ions are released from the polymer, using dilute acid, metal ion oxidation state adjustment, or competing chelating agents, and collected and recovered or disposed of by appropriate waste management techniques. The water-soluble polymer can then be recycled. Preferred water-soluble polymers include polyethyleneimine and polyethyleneimine having a catechol or hydroxamate group.

Coupled Spatio-Temporal Patterns of Solute Transport, Metabolism and Nutrient Uptake in Streams

NASA Astrophysics Data System (ADS)

Kurz, M. J.; Schmidt, C.

2017-12-01

Slower flow velocities and longer residence times within stream transient storage (TS) zones facilitate interaction between solutes and microbial communities, potentially increasing local rates of metabolic activity. Multiple factors, including channel morphology and substrate, variable hydrology, and seasonal changes in biological and physical parameters, result in changes in the solute transport dynamics and reactivity of TS zones over time and space. These changes would be expected to, in turn, influence rates of whole-stream ecosystem functions such as metabolism and nutrient uptake. However, the linkages between solute transport and ecosystem functioning within TS zones, and the contribution of TS zones to whole-stream functioning, are not always so straight forward. This may be due, in part, to methodological challenges. In this study we investigated the influence of stream channel hydro-morphology and substrate type on reach (103 m) and sub-reach (102 m) scale TS and ecosystem functioning. Patterns in solute transport, metabolism and nitrate uptake were tracked from April through October in two contrasting upland streams using several methods. The two streams, located in the Harz Mountains, Germany, are characterized by differing size (0.02 vs. 0.3 m3/s), dominant stream channel substrate (bedrock vs. alluvium) and sub-reach morphology (predominance of pools, riffles and glides). Solute transport parameters and respiration rates at the reach and sub-reach scale were estimated monthly from coupled pulse injections of the reactive tracer resazurin (Raz) and conservative tracers uranine and salt. Raz, a weakly fluorescent dye, irreversibly transforms to resorufin (Rru) under mildly reducing conditions, providing a proxy for aerobic respiration. Daily rates of primary productivity, respiration and nitrate retention at the reach scale were estimated using the diel cycles in dissolved oxygen and nitrate concentrations measured by in-situ sensors. Preliminary results indicate distinct differences in common metrics of TS and Raz transformation rates within and between the two streams. However, transformation rates and TS metrics are not well correlated, indicating complexities in the relationship between solute transport dynamics and metabolism in streams.

Modeling hyporheic zone processes

USGS Publications Warehouse

Runkel, Robert L.; McKnight, Diane M.; Rajaram, Harihar

2003-01-01

Stream biogeochemistry is influenced by the physical and chemical processes that occur in the surrounding watershed. These processes include the mass loading of solutes from terrestrial and atmospheric sources, the physical transport of solutes within the watershed, and the transformation of solutes due to biogeochemical reactions. Research over the last two decades has identified the hyporheic zone as an important part of the stream system in which these processes occur. The hyporheic zone may be loosely defined as the porous areas of the stream bed and stream bank in which stream water mixes with shallow groundwater. Exchange of water and solutes between the stream proper and the hyporheic zone has many biogeochemical implications, due to differences in the chemical composition of surface and groundwater. For example, surface waters are typically oxidized environments with relatively high dissolved oxygen concentrations. In contrast, reducing conditions are often present in groundwater systems leading to low dissolved oxygen concentrations. Further, microbial oxidation of organic materials in groundwater leads to supersaturated concentrations of dissolved carbon dioxide relative to the atmosphere. Differences in surface and groundwater pH and temperature are also common. The hyporheic zone is therefore a mixing zone in which there are gradients in the concentrations of dissolved gasses, the concentrations of oxidized and reduced species, pH, and temperature. These gradients lead to biogeochemical reactions that ultimately affect stream water quality. Due to the complexity of these natural systems, modeling techniques are frequently employed to quantify process dynamics.

The magnitude of lost ecosystem structure and function in urban streams and the effectiveness of watershed-based management (Invited)

NASA Astrophysics Data System (ADS)

Smucker, N. J.; Detenbeck, N. E.; Kuhn, A.

2013-12-01

Watershed development is a leading cause of stream impairment and increasingly threatens the availability, quality, and sustainability of freshwater resources. In a recent global meta-analysis, we found that measures of desirable ecological structure (e.g., algal, macroinvertebrate, and fish communities) and functions (e.g., metabolism, nutrient uptake, and denitrification) in streams with developed watersheds were only 23% and 34%, respectively, of those in minimally disturbed reference streams. As humans continue to alter watersheds in response to growing and migrating populations, characterizing ecological responses to watershed development and management practices is urgently needed to inform future development practices, decisions, and policy. In a study of streams in New England, we found that measures of macroinvertebrate and algal communities had threshold responses between 1-10% and 1-5% impervious cover, respectively. Macroinvertebrate communities had decreases in sensitive taxa and predators occurring from 1-3.5% and transitions in trophic and habitat guilds from 4-9% impervious cover. Sensitive algal taxa declined at 1%, followed by increases in tolerant taxa at 3%. Substantially altered algal communities persisted above 5% impervious cover and were dominated by motile taxa (sediment resistant) and those with high nutrient demands. Boosted regression tree analysis showed that sites with >65% and ideally >80% forest and wetland cover in near-stream buffers were associated with a 13-34% decrease in the effects of watershed impervious cover on algal communities. While this reduction is substantial, additional out-of-stream management efforts are needed to protect and restore stream ecosystems (e.g., created wetlands and stormwater ponds), but understanding their effectiveness is greatly limited by sparse ecological monitoring. Our meta-analysis found that restoration improved ecological structure and functions in streams by 48% and 14%, respectively, when compared to streams with developed watersheds and no management practices in place. However, ecosystem measures at restored sites were still only 53% of those in minimally disturbed reference streams. Some of our ongoing work further examines how watershed development and riparian condition affect stream ecosystem functions by altering the sources and delivery of nutrients and carbon. Our results can help inform management priorities and expectations, and they emphasize the importance of implementing mindful development and protective actions in a watershed context, especially in watersheds near impervious cover thresholds. Continued research on linked terrestrial-aquatic systems, improved BMP tracking, and ongoing monitoring will be essential to conserving and restoring the mechanisms that sustain valued ecological attributes and ecosystem services of streams.

Apparatus and method for two-stage oxidation of wastes

DOEpatents

Fleischman, Scott D.

1995-01-01

An apparatus and method for oxidizing wastes in a two-stage process. The apparatus includes an oxidation device, a gas-liquid contacting column and an electrocell. In the first stage of the process, wastes are heated in the presence of air to partially oxidize the wastes. The heated wastes produce an off-gas stream containing oxidizable materials. In the second stage, the off-gas stream is cooled and flowed through the contacting column, where the off-gas stream is contacted with an aqueous acid stream containing an oxidizing agent having at least two positive valence states. At least a portion of the oxidizable materials are transferred to the acid stream and destroyed by the oxidizing agent. During oxidation, the valence of the oxidizing agent is decreased from its higher state to its lower state. The acid stream is flowed to the electrocell, where an electric current is applied to the stream to restore the oxidizing agent to its higher valence state. The regenerated acid stream is recycled to the contacting column.

Method for separating water soluble organics from a process stream by aqueous biphasic extraction

DOEpatents

Chaiko, David J.; Mego, William A.

1999-01-01

A method for separating water-miscible organic species from a process stream by aqueous biphasic extraction is provided. An aqueous biphase system is generated by contacting a process stream comprised of water, salt, and organic species with an aqueous polymer solution. The organic species transfer from the salt-rich phase to the polymer-rich phase, and the phases are separated. Next, the polymer is recovered from the loaded polymer phase by selectively extracting the polymer into an organic phase at an elevated temperature, while the organic species remain in a substantially salt-free aqueous solution. Alternatively, the polymer is recovered from the loaded polymer by a temperature induced phase separation (cloud point extraction), whereby the polymer and the organic species separate into two distinct solutions. The method for separating water-miscible organic species is applicable to the treatment of industrial wastewater streams, including the extraction and recovery of complexed metal ions from salt solutions, organic contaminants from mineral processing streams, and colorants from spent dye baths.

Woody plant communities along urban, suburban, and rural streams in Louisville, Kentucky, USA

Treesearch

R. Jonathan White; Margaret M. Carreiro; Wayne C. Zipperer

2014-01-01

Anthropogenic changes in land use and cover (LULC) in stream catchments can alter the composition of riparian plant communities, which can affect ecosystem functions of riparian areas and streams from local to landscape scales.We conducted a study to determine if woody plant species composition and abundance along headwater streams were correlated with categorical and...

The importance of wood in headwater streams of the Oregon Coast Range

USGS Publications Warehouse

May, Christine; Gresswell, Robert E.; Erickson, Janet L.

2004-01-01

Although headwater streams comprise the majority of stream length in mountainous regions, little is known about their form and function in comparison to higher-order rivers. A better understanding of the role of headwater streams in routing water, wood, and sediment is needed to clarify the physical and biological connections among uplands, riparian zones, and downstream reaches.

Evaluating Best Management Practices for ephemeral channel protection following forest harvest in the Cumberland Plateau - preliminary findings

Treesearch

Emma L. Witt; Christopher D. Barton; Jeffrey W. Stringer; Daniel W. Bowker; Randall K. Kolka

2011-01-01

Most states in the United States have established forestry best management practices to protect water quality and maintain aquatic habitat in streams. However, guidelines are generally focused on minimizing impacts to perennial streams. Ephemeral channels (or streams), which function as important delivery systems for carbon, nutrients, and sediment to perennial streams...

Alternative Procedure of Heat Integration Tehnique Election between Two Unit Processes to Improve Energy Saving

NASA Astrophysics Data System (ADS)

Santi, S. S.; Renanto; Altway, A.

2018-01-01

The energy use system in a production process, in this case heat exchangers networks (HENs), is one element that plays a role in the smoothness and sustainability of the industry itself. Optimizing Heat Exchanger Networks (HENs) from process streams can have a major effect on the economic value of an industry as a whole. So the solving of design problems with heat integration becomes an important requirement. In a plant, heat integration can be carried out internally or in combination between process units. However, steps in the determination of suitable heat integration techniques require long calculations and require a long time. In this paper, we propose an alternative step in determining heat integration technique by investigating 6 hypothetical units using Pinch Analysis approach with objective function energy target and total annual cost target. The six hypothetical units consist of units A, B, C, D, E, and F, where each unit has the location of different process streams to the temperature pinch. The result is a potential heat integration (ΔH’) formula that can trim conventional steps from 7 steps to just 3 steps. While the determination of the preferred heat integration technique is to calculate the potential of heat integration (ΔH’) between the hypothetical process units. Completion of calculation using matlab language programming.

The dynamic imprint of word learning on the dorsal language pathway.

PubMed

Palomar-García, María-Ángeles; Sanjuán, Ana; Bueichekú, Elisenda; Ventura-Campos, Noelia; Ávila, César

2017-10-01

According to Hickok and Poeppel (2007), the acquisition of new vocabulary rests on the dorsal language pathway connecting auditory and motor areas. The present study tested this hypothesis longitudinally by measuring BOLD signal changes during a verbal repetition task and modulation of resting state functional connectivity (rs-FC) in the dorsal stream. Thirty-five healthy participants, divided into trained and control groups, completed fMRI sessions on days 1, 10, and 24. Between days 1 and 10, the trained group learned 84 new pseudowords associated with 84 native words. Task-related fMRI results showed a reduced activity in the IFG and STG while processing the learned vocabulary after training, returning to initial values two weeks later. Moreover, rs-fMRI analysis showed stronger rs-FC between the IFG and STG in the trained group than in the control group after learning, especially on day 24. These neural changes were more evident in participants with a larger vocabulary. Discussion focuses on the prominent role of the dorsal stream in vocabulary acquisition. Even when their meaning was known, newly learned words were again processed through the dorsal stream two weeks after learning, with the increase in rs-FC between auditory and motor areas being a relevant long-term imprint of vocabulary learning. Copyright © 2017 Elsevier Inc. All rights reserved.

Valuing and selling a practice.

PubMed

Sullivan, Walter

2012-11-01

Surgeons, as they contemplate retirement, wrongly believe that their practices do not have financial value. In fact, a well-organized efficiently functioning office with an emphasis on excellent service in combination with a constant stream of patients make it financially ideal for the new surgeon. Being able to assume such a practice can be a very smart financial decision. The practice's worth can be determined by a careful analysis of the practice financials and an evaluation of the functioning of the office and employees. Purchasing such a practice can be, economically, a very smart move by a new surgeon. Payments are made over time at a rate that allows the surgeon to make a good living, leaving him with real equity once the payments are complete. The departing surgeon, who had spent years building this successful practice, gets some of this value back in the form of an income stream to supplement his retirement. This process should be considered in virtually every case. Do not just "close the door."

A new neural framework for visuospatial processing

PubMed Central

Kravitz, Dwight J.; Saleem, Kadharbatcha S.; Baker, Chris I.; Mishkin, Mortimer

2012-01-01

The division of cortical visual processing into distinct dorsal and ventral streams is a key framework that has guided visual neuroscience. The characterization of the ventral stream as a ‘What’ pathway is relatively uncontroversial, but the nature of dorsal stream processing is less clear. Originally proposed as mediating spatial perception (‘Where’), more recent accounts suggest it primarily serves non-conscious visually guided action (‘How’). Here, we identify three pathways emerging from the dorsal stream that consist of projections to the prefrontal and premotor cortices, and a major projection to the medial temporal lobe that courses both directly and indirectly through the posterior cingulate and retrosplenial cortices. These three pathways support both conscious and non-conscious visuospatial processing, including spatial working memory, visually guided action and navigation, respectively. PMID:21415848

Melting beneath Greenland outlet glaciers and ice streams

NASA Astrophysics Data System (ADS)

Alexander, David; Perrette, Mahé; Beckmann, Johanna

2015-04-01

Basal melting of fast-flowing Greenland outlet glaciers and ice streams due to frictional heating at the ice-bed interface contributes significantly to total glacier mass balance and subglacial meltwater flux, yet modelling this basal melt process in Greenland has received minimal research attention. A one-dimensional dynamic ice-flow model is calibrated to the present day longitudinal profiles of 10 major Greenland outlet glaciers and ice streams (including the Jakobshavn Isbrae, Petermann Glacier and Helheim Glacier) and is validated against published ice flow and surface elevation measurements. Along each longitudinal profile, basal melt is calculated as a function of ice flow velocity and basal shear stress. The basal shear stress is dependent on the effective pressure (difference between ice overburden pressure and water pressure), basal roughness and a sliding parametrization. Model output indicates that where outlet glaciers and ice streams terminate into the ocean with either a small floating ice tongue or no floating tongue whatsoever, the proportion of basal melt to total melt (surface, basal and submarine melt) is 5-10% (e.g. Jakobshavn Isbrae; Daugaard-Jensen Glacier). This proportion is, however, negligible where larger ice tongues lose mass mostly by submarine melt (~1%; e.g. Nioghalvfjerdsfjorden Glacier). Modelled basal melt is highest immediately upvalley of the grounding line, with contributions typically up to 20-40% of the total melt for slippery beds and up to 30-70% for resistant beds. Additionally, modelled grounding line and calving front migration inland for all outlet glaciers and ice streams of hundreds of metres to several kilometres occurs. Including basal melt due to frictional heating in outlet glacier and ice stream models is important for more accurately modelling mass balance and subglacial meltwater flux, and therefore, more accurately modelling outlet glacier and ice stream dynamics and responses to future climate change.

International Critical Zone Science: Opportunities to Build a Global Understanding of Land-Water Linkages

NASA Astrophysics Data System (ADS)

McDowell, W. H.

2015-12-01

Critical Zone science examines the structure and properties of the thin veneer that links surface properties to deep geology, at time scales of seconds to millennia. One of the fundamental premises of the US Critical Zone Observatories program is that CZOs should include some measurements made in common at all sites, as these common measurements will enable us to make stronger inferences about how the structure and function of the critical zone interact to drive key processes such as soil formation, stream flow generation, and nutrient export. Recent advances in real-time sensors provide new opportunities to address some fundamental questions about how hillslope soils and streams are linked. Data from the Luquillo Critical Zone Observatory in Puerto Rico, for example, document a previously undescribed transition, or flipping, of stream and soil biogeochemistry in a tropical rain forest. Under typical conditions, soil moisture is high and soil oxygen content is often low, especially at depth. Streams, in contrast, are typically near oxygen saturation. Under severe drought, however, oxygen increases dramatically in soil air and declines to values that are well below saturation in streams. This flipping in redox conditions suggests that despite the strong hydrologic connection between hillslope and stream, gas dynamics and potentially solute dynamics are decoupled along the flow path. The international CZO community has the opportunity to develop a suite of sensor arrays to document soil air, groundwater chemistry, and stream water chemistry. Progress towards realizing the potential of these international networks to develop coherent sensor programs will be addressed based on the current status of sensor deployments in CZO networks in the US, China, and Europe.

Bioaccumulation syndrome: identifying factors that make some stream food webs prone to elevated mercury bioaccumulation

PubMed Central

Ward, Darren M.; Nislow, Keith H.; Folt, Carol L.

2010-01-01

Mercury is a ubiquitous contaminant in aquatic ecosystems, posing a significant health risk to humans and wildlife that eat fish. Mercury accumulates in aquatic food webs as methylmercury (MeHg), a particularly toxic and persistent organic mercury compound. While mercury in the environment originates largely from anthropogenic activities, MeHg accumulation in freshwater aquatic food webs is not a simple function of local or regional mercury pollution inputs. Studies show that even sites with similar mercury inputs can produce fish with mercury concentrations ranging over an order of magnitude. While much of the foundational work to identify the drivers of variation in mercury accumulation has focused on freshwater lakes, mercury contamination in stream ecosystems is emerging as an important research area. Here, we review recent research on mercury accumulation in stream-dwelling organisms. Taking a hierarchical approach, we identify a suite of characteristics of individual consumers, food webs, streams, watersheds, and regions that are consistently associated with elevated MeHg concentrations in stream fish. We delineate a conceptual, mechanistic basis for explaining the ecological processes that underlie this vulnerability to MeHg. Key factors, including suppressed individual growth of consumers, low rates of primary and secondary production, hydrologic connection to methylation sites (e.g. wetlands), heavily forested catchments, and acidification are frequently associated with increased MeHg concentrations in fish across both streams and lakes. Hence, we propose that these interacting factors define a syndrome of characteristics that drive high MeHg production and bioaccumulation rates across these freshwater aquatic ecosystems. Finally, based on an understanding of the ecological drivers of MeHg accumulation, we identify situations when anthropogenic effects and management practices could significantly exacerbate or ameliorate MeHg accumulation in stream fish. PMID:20536817

Ground water stratification and delivery of nitrate to an incised stream under varying flow conditions.

PubMed

Böhlke, J K; O'Connell, Michael E; Prestegaard, Karen L

2007-01-01

Ground water processes affecting seasonal variations of surface water nitrate concentrations were investigated in an incised first-order stream in an agricultural watershed with a riparian forest in the coastal plain of Maryland. Aquifer characteristics including sediment stratigraphy, geochemistry, and hydraulic properties were examined in combination with chemical and isotopic analyses of ground water, macropore discharge, and stream water. The ground water flow system exhibits vertical stratification of hydraulic properties and redox conditions, with sub-horizontal boundaries that extend beneath the field and adjacent riparian forest. Below the minimum water table position, ground water age gradients indicate low recharge rates (2-5 cm yr(-1)) and long residence times (years to decades), whereas the transient ground water wedge between the maximum and minimum water table positions has a relatively short residence time (months to years), partly because of an upward increase in hydraulic conductivity. Oxygen reduction and denitrification in recharging ground waters are coupled with pyrite oxidation near the minimum water table elevation in a mottled weathering zone in Tertiary marine glauconitic sediments. The incised stream had high nitrate concentrations during high flow conditions when much of the ground water was transmitted rapidly across the riparian zone in a shallow oxic aquifer wedge with abundant outflow macropores, and low nitrate concentrations during low flow conditions when the oxic wedge was smaller and stream discharge was dominated by upwelling from the deeper denitrified parts of the aquifer. Results from this and similar studies illustrate the importance of near-stream geomorphology and subsurface geology as controls of riparian zone function and delivery of nitrate to streams in agricultural watersheds.

Ground water stratification and delivery of nitrate to an incised stream under varying flow conditions

USGS Publications Warehouse

Böhlke, J.K.; O'Connell, M. E.; Prestegaard, K.L.

2007-01-01

Ground water processes affecting seasonal variations of surface water nitrate concentrations were investigated in an incised first-order stream in an agricultural watershed with a riparian forest in the coastal plain of Maryland. Aquifer characteristics including sediment stratigraphy, geochemistry, and hydraulic properties were examined in combination with chemical and isotopic analyses of ground water, macropore discharge, and stream water. The ground water flow system exhibits vertical stratification of hydraulic properties and redox conditions, with sub-horizontal boundaries that extend beneath the field and adjacent riparian forest. Below the minimum water table position, ground water age gradients indicate low recharge rates (2-5 cm yr-1) and long residence times (years to decades), whereas the transient ground water wedge between the maximum and minimum water table positions has a relatively short residence time (months to years), partly because of an upward increase in hydraulic conductivity. Oxygen reduction and denitrification in recharging ground waters are coupled with pyrite oxidation near the minimum water table elevation in a mottled weathering zone in Tertiary marine glauconitic sediments. The incised stream had high nitrate concentrations during high flow conditions when much of the ground water was transmitted rapidly across the riparian zone in a shallow oxic aquifer wedge with abundant outflow macropores, and low nitrate concentrations during low flow conditions when the oxic wedge was smaller and stream discharge was dominated by upwelling from the deeper denitrified parts of the aquifer. Results from this and similar studies illustrate the importance of near-stream geomorphology and subsurface geology as controls of riparian zone function and delivery of nitrate to streams in agricultural watersheds. ?? ASA, CSSA, SSSA.

Developing an Environmental Decision Support System for Stream Management: the STREAMES Experience

NASA Astrophysics Data System (ADS)

Riera, J.; Argerich, A.; Comas, J.; Llorens, E.; Martí, E.; Godé, L.; Pargament, D.; Puig, M.; Sabater, F.

2005-05-01

Transferring research knowledge to stream managers is crucial for scientifically sound management. Environmental decision support systems are advocated as an effective means to accomplish this. STREAMES (STream REAach Management: an Expert System) is a decision tree based EDSS prototype developed within the context of an European project as a tool to assist water managers in the diagnosis of problems, detection of causes, and selection of management strategies for coping with stream degradation issues related mostly to excess nutrient availability. STREAMES was developed by a team of scientists, water managers, and experts in knowledge engineering. Although the tool focuses on management at the stream reach scale, it also incorporates a mass-balance catchment nutrient emission model and a simple GIS module. We will briefly present the prototype and share our experience in its development. Emphasis will be placed on the process of knowledge acquisition, the design process, the pitfalls and benefits of the communication between scientists and managers, and the potential for future development of STREAMES, particularly in the context of the EU Water Framework Directive.

Novel high-molecular weight fucosylated milk oligosaccharides identified in dairy streams.

PubMed

Mehra, Raj; Barile, Daniela; Marotta, Mariarosaria; Lebrilla, Carlito B; Chu, Caroline; German, J Bruce

2014-01-01

Oligosaccharides are the third largest component in human milk. This abundance is remarkable because oligosaccharides are not digestible by the newborn, and yet they have been conserved and amplified during evolution. In addition to encouraging the growth of a protective microbiota dominated by bifidobacteria, oligosaccharides have anti-infective activity, preventing pathogens from binding to intestinal cells. Although it would be advantageous adding these valuable molecules to infant milk formula, the technologies to reproduce the variety and complexity of human milk oligosaccharides by enzymatic/organic synthesis are not yet mature. Consequently, there is an enormous interest in alternative sources of these valuable oligosaccharides. Recent research has demonstrated that bovine milk and whey permeate also contain oligosaccharides. Thus, a thorough characterization of oligosaccharides in bovine dairy streams is an important step towards fully assessing their specific functionalities. In this study, bovine milk oligosaccharides (BMOs) were concentrated by membrane filtration from a readily available dairy stream called "mother liquor", and analyzed by high accuracy MALDI FT-ICR mass spectrometry. The combination of HPLC and accurate mass spectrometry allowed the identification of ideal processing conditions leading to the production of Kg amount of BMO enriched powders. Among the BMOs identified, 18 have high-molecular weight and corresponded in size to the most abundant oligosaccharides present in human milk. Notably 6 oligosaccharides contained fucose, a sugar monomer that is highly abundant in human milk, but is rarely observed in bovine milk. This work shows that dairy streams represent a potential source of complex milk oligosaccharides for commercial development of unique dairy ingredients in functional foods that reproduce the benefits of human milk.

Spatial and successional dynamics of microbial biofilm communities in a grassland stream ecosystem

DOE PAGES

Veach, Allison M.; Stegen, James C.; Brown, Shawn P.; ...

2016-09-06

Biofilms represent a metabolically active and structurally complex component of freshwater ecosystems. Ephemeral prairie streams are hydrologically harsh and prone to frequent perturbation. Elucidating both functional and structural community changes over time within prairie streams provides a general understanding of microbial responses to environmental disturbance. In this study, we examined microbial succession of biofilm communities at three sites in a third-order stream at Konza Prairie over a 2- to 64-day period. Microbial abundance (bacterial abundance, chlorophyll a concentrations) increased and never plateaued during the experiment. Net primary productivity (net balance of oxygen consumption and production) of the developing biofilms didmore » not differ statistically from zero until 64 days suggesting a balance of the use of autochthonous and allochthonous energy sources until late succession. Bacterial communities (MiSeq analyses of the V4 region of 16S rRNA) established quickly. Bacterial richness, diversity and evenness were high after 2 days and increased over time. Several dominant bacterial phyla (Beta-, Alphaproteobacteria, Bacteroidetes, Gemmatimonadetes, Acidobacteria, Chloroflexi) and genera ( Luteolibacter, Flavobacterium, Gemmatimonas, Hydrogenophaga) differed in relative abundance over space and time. Bacterial community composition differed across both space and successional time. Pairwise comparisons of phylogenetic turnover in bacterial community composition indicated that early-stage succession (≤16 days) was driven by stochastic processes, whereas later stages were driven by deterministic selection regardless of site. Finally, our data suggest that microbial biofilms predictably develop both functionally and structurally indicating distinct successional trajectories of bacterial communities in this ecosystem.« less

Spatial and successional dynamics of microbial biofilm communities in a grassland stream ecosystem

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

Veach, Allison M.; Stegen, James C.; Brown, Shawn P.

Biofilms represent a metabolically active and structurally complex component of freshwater ecosystems. Ephemeral prairie streams are hydrologically harsh and prone to frequent perturbation. Elucidating both functional and structural community changes over time within prairie streams provides a general understanding of microbial responses to environmental disturbance. In this study, we examined microbial succession of biofilm communities at three sites in a third-order stream at Konza Prairie over a 2- to 64-day period. Microbial abundance (bacterial abundance, chlorophyll a concentrations) increased and never plateaued during the experiment. Net primary productivity (net balance of oxygen consumption and production) of the developing biofilms didmore » not differ statistically from zero until 64 days suggesting a balance of the use of autochthonous and allochthonous energy sources until late succession. Bacterial communities (MiSeq analyses of the V4 region of 16S rRNA) established quickly. Bacterial richness, diversity and evenness were high after 2 days and increased over time. Several dominant bacterial phyla (Beta-, Alphaproteobacteria, Bacteroidetes, Gemmatimonadetes, Acidobacteria, Chloroflexi) and genera ( Luteolibacter, Flavobacterium, Gemmatimonas, Hydrogenophaga) differed in relative abundance over space and time. Bacterial community composition differed across both space and successional time. Pairwise comparisons of phylogenetic turnover in bacterial community composition indicated that early-stage succession (≤16 days) was driven by stochastic processes, whereas later stages were driven by deterministic selection regardless of site. Finally, our data suggest that microbial biofilms predictably develop both functionally and structurally indicating distinct successional trajectories of bacterial communities in this ecosystem.« less

Hydrology and Hyporheic Nitrogen Biogeochemistry in a Geomorphically Degraded Urban Stream

EPA Science Inventory

Few studies have investigated the relationship between hydrology and nitrogen biogeochemistry in hyporheic zones of degraded urban streams despite significant national efforts to restore such streams in attempts to improve the nutrient uptake functions in these ecosystems. We ex...

Operational Draft Regional Guidebook for the Functional Assessment of High-Gradient Headwater Streams and Low-Gradient Perennial Streams in Appalachia

DTIC Science & Technology

rapid assessments provided in this guidebook utilize structural components of streams and their watershed and can be used in conjunction with assessment of water quality and biotic communities if desired.

Operational Draft Regional Guidebook for the Functional Assessment of High-gradient Ephemeral and Intermittent Headwater Streams in Western West Virginia and Eastern Kentucky

DTIC Science & Technology

2010-07-01

VCCANOPY applies to the habitat function only. Channel canopy cover affects the temperature, nutrient cycling, and habitat of riparian and stream...altering amphibian habitat. Changes in canopy cover and composition affect the quality of stream inputs from the riparian zone (Wipfli et al. 2007) and the...systems (Mulholland 1992). Riparian plant communities provide habitat and are affected by canopy shading, with shade-tolerant species germinating

Evaluation of Topographic wetness index and catchment characteristics on spatially and temporally variable streams across an elevation gradient

NASA Astrophysics Data System (ADS)

Martin, C.

2017-12-01

Topography can be used to delineate streams and quantify the topographic control on hydrological processes of a watershed because geomorphologic processes have shaped the topography and streams of a catchment over time. Topographic Wetness index (TWI) is a common index used for delineating stream networks by predicting location of saturation excess overland flow, but is also used for other physical attributes of a watershed such as soil moisture, groundwater level, and vegetation patterns. This study evaluates how well TWI works across an elevation gradient and the relationships between the active drainage network of four headwater watersheds at various elevations in the Colorado Front Range to topography, geology, climate, soils, elevation, and vegetation in attempt to determine the controls on streamflow location and duration. The results suggest that streams prefer to flow along a path of least resistance which including faults and permeable lithology. Permeable lithologies created more connectivity of stream networks during higher flows but during lower flows dried up. Streams flowing over impermeable lithologies had longer flow duration. Upslope soil hydraulic conductivity played a role on stream location, where soils with low hydraulic conductivity had longer flow duration than soils with higher hydraulic conductivity.Finally TWI thresholds ranged from 5.95 - 10.3 due to changes in stream length and to factors such as geology and soil. TWI had low accuracy for the lowest elevation site due to the greatest change of stream length. In conclusion, structural geology, upslope soil texture, and the permeability of the underlying lithology influenced where the stream was flowing and for how long. Elevation determines climate which influences the hydrologic processes occurring at the watersheds and therefore affects the duration and timing of streams at different elevations. TWI is an adequate tool for delineating streams because results suggest topography has a primary control on the stream locations, but because intermittent streams change throughout the year a algorithm needs to be created to correspond to snow melt and rain events. Also geology indices and soil indices need be considered in addition to topography to have the most accurate derived stream network.

Method for processing aqueous wastes

DOEpatents

Pickett, J.B.; Martin, H.L.; Langton, C.A.; Harley, W.W.

1993-12-28

A method is presented for treating waste water such as that from an industrial processing facility comprising the separation of the waste water into a dilute waste stream and a concentrated waste stream. The concentrated waste stream is treated chemically to enhance precipitation and then allowed to separate into a sludge and a supernate. The supernate is skimmed or filtered from the sludge and blended with the dilute waste stream to form a second dilute waste stream. The sludge remaining is mixed with cementitious material, rinsed to dissolve soluble components, then pressed to remove excess water and dissolved solids before being allowed to cure. The dilute waste stream is also chemically treated to decompose carbonate complexes and metal ions and then mixed with cationic polymer to cause the precipitated solids to flocculate. Filtration of the flocculant removes sufficient solids to allow the waste water to be discharged to the surface of a stream. The filtered material is added to the sludge of the concentrated waste stream. The method is also applicable to the treatment and removal of soluble uranium from aqueous streams, such that the treated stream may be used as a potable water supply. 4 figures.

The Stream Table in Physical Geography Instruction.

ERIC Educational Resources Information Center

Wikle, Thomas A.; Lightfoot, Dale R.

1997-01-01

Outlines a number of activities to be conducted with a stream table (large wooden box filled with sediment and designed for water to pass through) in class. Activities illustrate such fluvial processes as stream meandering, erosion, transportation, and deposition. Includes a diagram for constructing a stream table. (MJP)

THE EMERGING USE OF LIDAR AS A TOOL FOR ASSESSING WATERSHED MORPHOLOGY

EPA Science Inventory

Stream channel morphology is an integral component of the stream fluvial process and is inherently related to the stability of stream aquatic ecology. Numerous studies have shown that changes in stream channel geometry are related to changes in biotic integrity. In urbanizing la...