Automated grouping of action potentials of human embryonic stem cell-derived cardiomyocytes.

Science.gov (United States)

Gorospe, Giann; Zhu, Renjun; Millrod, Michal A; Zambidis, Elias T; Tung, Leslie; Vidal, Rene

2014-09-01

Methods for obtaining cardiomyocytes from human embryonic stem cells (hESCs) are improving at a significant rate. However, the characterization of these cardiomyocytes (CMs) is evolving at a relatively slower rate. In particular, there is still uncertainty in classifying the phenotype (ventricular-like, atrial-like, nodal-like, etc.) of an hESC-derived cardiomyocyte (hESC-CM). While previous studies identified the phenotype of a CM based on electrophysiological features of its action potential, the criteria for classification were typically subjective and differed across studies. In this paper, we use techniques from signal processing and machine learning to develop an automated approach to discriminate the electrophysiological differences between hESC-CMs. Specifically, we propose a spectral grouping-based algorithm to separate a population of CMs into distinct groups based on the similarity of their action potential shapes. We applied this method to a dataset of optical maps of cardiac cell clusters dissected from human embryoid bodies. While some of the nine cell clusters in the dataset are presented with just one phenotype, the majority of the cell clusters are presented with multiple phenotypes. The proposed algorithm is generally applicable to other action potential datasets and could prove useful in investigating the purification of specific types of CMs from an electrophysiological perspective.

The role of house surveys in geological radon potential mapping

International Nuclear Information System (INIS)

Ball, K.

1997-01-01

Because radon levels vary widely between apparently identical buildings on the same geological unit, no map can predict the radon level in an individual building. Maps can, however, give the probability that a building in a particular locality is above a threshold of radon concentration such as a reference or action level. The probability may be calculated for a particular building type or for a mixture of building types. In the latter case the probability is in effect an estimate of the proportion of buildings above the threshold level. Alternatively maps can provide estimates of the mean radon levels in buildings by area. Maps showing the geographical variation in probability that new or existing building will exceed a radon reference level are used to prevent excessive exposures to radon. The information may be used in various ways, such as to target information campaigns encouraging measurement of radon levels in homes or to modify regulations for new buildings. The data which are used to provide the estimates of the proportion of buildings above a threshold may be radon measurements results from a sample of buildings, or may be indirect indicators such as ground radium concentrations, emanation coefficients and permeability measurements. Consistency in radon measurement protocols and detailed positional information are prerequisites for mapping radon prone areas based upon house data. Grouping building radon measurements by geological formation and superficial cover can produce radon potential maps which are more spatially accurate than grid square maps and more accurate in estimating numbers of homes affected than mapping based only on measuring geological and pedagogical properties

RISK COMMUNICATION IN ACTION: THE TOOLS OF MESSAGE MAPPING

Science.gov (United States)

Risk Communication in Action: The Tools of Message Mapping, is a workbook designed to guide risk communicators in crisis situations. The first part of this workbook will review general guidelines for risk communication. The second part will focus on one of the most robust tools o...

Creating Geologically Based Radon Potential Maps for Kentucky

Science.gov (United States)

Overfield, B.; Hahn, E.; Wiggins, A.; Andrews, W. M., Jr.

2017-12-01

Radon potential in the United States, Kentucky in particular, has historically been communicated using a single hazard level for each county; however, physical phenomena are not controlled by administrative boundaries, so single-value county maps do not reflect the significant variations in radon potential in each county. A more accurate approach uses bedrock geology as a predictive tool. A team of nurses, health educators, statisticians, and geologists partnered to create 120 county maps showing spatial variations in radon potential by intersecting residential radon test kit results (N = 60,000) with a statewide 1:24,000-scale bedrock geology coverage to determine statistically valid radon-potential estimates for each geologic unit. Maps using geology as a predictive tool for radon potential are inherently more detailed than single-value county maps. This mapping project revealed that areas in central and south-central Kentucky with the highest radon potential are underlain by shales and karstic limestones.

Implementation of structure-mapping inference by event-file binding and action planning: a model of tool-improvisation analogies.

Science.gov (United States)

Fields, Chris

2011-03-01

Structure-mapping inferences are generally regarded as dependent upon relational concepts that are understood and expressible in language by subjects capable of analogical reasoning. However, tool-improvisation inferences are executed by members of a variety of non-human primate and other species. Tool improvisation requires correctly inferring the motion and force-transfer affordances of an object; hence tool improvisation requires structure mapping driven by relational properties. Observational and experimental evidence can be interpreted to indicate that structure-mapping analogies in tool improvisation are implemented by multi-step manipulation of event files by binding and action-planning mechanisms that act in a language-independent manner. A functional model of language-independent event-file manipulations that implement structure mapping in the tool-improvisation domain is developed. This model provides a mechanism by which motion and force representations commonly employed in tool-improvisation structure mappings may be sufficiently reinforced to be available to inwardly directed attention and hence conceptualization. Predictions and potential experimental tests of this model are outlined.

Screening action potentials: The power of light

Directory of Open Access Journals (Sweden)

Lars eKaestner

2011-07-01

Full Text Available Action potentials reflect the concerted activity of all electrogenic constituents in the plasma membrane during the excitation of a cell. Therefore, the action potential is an integrated readout and a promising parameter to detect electrophysiological failures or modifications thereof in diagnosis as well as in drug screens. Cellular action potentials can be recorded by optical approaches. To fulfill the pre-requirements to scale up for e.g. pharmacological screens the following preparatory work has to be provided: (i model cells under investigation need to represent target cells in the best possible manner; (ii optical sensors that can be either small molecule dyes or genetically encoded potential probes need to provide a reliable readout with minimal interaction with the naive behavior of the cells and (iii devices need to be capable to stimulate the cells, read out the signals with the appropriate speed as well as provide the capacity for a sufficient throughput. Here we discuss several scenarios for all three categories in the field of cardiac physiology and pharmacology and provide a perspective to use the power of light in screening cardiac action potentials.

Is action potential threshold lowest in the axon?

NARCIS (Netherlands)

Kole, Maarten H. P.; Stuart, Greg J.

2008-01-01

Action potential threshold is thought to be lowest in the axon, but when measured using conventional techniques, we found that action potential voltage threshold of rat cortical pyramidal neurons was higher in the axon than at other neuronal locations. In contrast, both current threshold and voltage

Calculation of stochastic broadening due to low mn magnetic perturbation in the simple map in action-angle coordinates

Science.gov (United States)

Hinton, Courtney; Punjabi, Alkesh; Ali, Halima

2009-11-01

The simple map is the simplest map that has topology of divertor tokamaks [A. Punjabi, H. Ali, T. Evans, and A. Boozer, Phys. Let. A 364, 140--145 (2007)]. Recently, the action-angle coordinates for simple map are analytically calculated, and simple map is constructed in action-angle coordinates [O. Kerwin, A. Punjabi, and H. Ali, Phys. Plasmas 15, 072504 (2008)]. Action-angle coordinates for simple map cannot be inverted to real space coordinates (R,Z). Because there is logarithmic singularity on the ideal separatrix, trajectories cannot cross separatrix [op cit]. Simple map in action-angle coordinates is applied to calculate stochastic broadening due to the low mn magnetic perturbation with mode numbers m=1, and n=±1. The width of stochastic layer near the X-point scales as 0.63 power of the amplitude δ of low mn perturbation, toroidal flux loss scales as 1.16 power of δ, and poloidal flux loss scales as 1.26 power of δ. Scaling of width deviates from Boozer-Rechester scaling by 26% [A. Boozer, and A. Rechester, Phys. Fluids 21, 682 (1978)]. This work is supported by US Department of Energy grants DE-FG02-07ER54937, DE-FG02-01ER54624 and DE-FG02-04ER54793.

Action potential propagation: ion current or intramembrane electric field?

Science.gov (United States)

Martí, Albert; Pérez, Juan J; Madrenas, Jordi

2018-01-01

The established action potential propagation mechanisms do not satisfactorily explain propagation on myelinated axons given the current knowledge of biological channels and membranes. The flow across ion channels presents two possible effects: the electric potential variations across the lipid bilayers (action potential) and the propagation of an electric field through the membrane inner part. The proposed mechanism is based on intra-membrane electric field propagation, this propagation can explain the action potential saltatory propagation and its constant delay independent of distance between Ranvier nodes in myelinated axons.

Selective effects of an octopus toxin on action potentials

Science.gov (United States)

Dulhunty, Angela; Gage, Peter W.

1971-01-01

1. A lethal, water soluble toxin (Maculotoxin, MTX) with a molecular weight less than 540, can be extracted from the salivary glands of an octopus (Hapalochlaena maculosa). 2. MTX blocks action potentials in sartorius muscle fibres of toads without affecting the membrane potential. Delayed rectification is not inhibited by the toxin. 3. At low concentrations (10-6-10-5 g/ml.) MTX blocks action potentials only after a certain number have been elicited. The number of action potentials, which can be defined accurately, depends on the concentration of MTX and the concentration of sodium ions in the extracellular solution. 4. The toxin has no post-synaptic effect at the neuromuscular junction and it is concluded that it blocks neuromuscular transmission by inhibiting action potentials in motor nerve terminals. PMID:4330930

Methodology developed to make the Quebec indoor radon potential map

International Nuclear Information System (INIS)

Drolet, Jean-Philippe; Martel, Richard; Poulin, Patrick; Dessau, Jean-Claude

2014-01-01

This paper presents a relevant approach to predict the indoor radon potential based on the combination of the radiogeochemical data and the indoor radon measurements in the Quebec province territory (Canada). The Quebec ministry of health asked for such a map to identify the radon-prone areas to manage the risk for the population related to indoor radon exposure. Three radiogeochemical criteria including (1) equivalent uranium (eU) concentration from airborne surface gamma-ray surveys, (2) uranium concentration measurements in sediments, (3) bedrock and surficial geology were combined with 3082 basement radon concentration measurements to identify the radon-prone areas. It was shown that it is possible to determine thresholds for the three criteria that implied statistically significant different levels of radon potential using Kruskal–Wallis one way analyses of variance by ranks. The three discretized radiogeochemical datasets were combined into a total predicted radon potential that sampled 98% of the studied area. The combination process was also based on Kruskal–Wallis one way ANOVA. Four statistically significant different predicted radon potential levels were created: low, medium, high and very high. Respectively 10 and 13% of the dwellings exceed the Canadian radon guideline of 200 Bq/m 3 in low and medium predicted radon potentials. These proportions rise up to 22 and 45% respectively for high and very high predicted radon potentials. This predictive map of indoor radon potential based on the radiogeochemical data was validated using a map of confirmed radon exposure in homes based on the basement radon measurements. It was shown that the map of predicted radon potential based on the radiogeochemical data was reliable to identify radon-prone areas even in zones where no indoor radon measurement exists. - Highlights: • 5 radiogeochemical datasets were used to map the geogenic indoor radon potential. • An indoor radon potential was determined for each

Quadratic adaptive algorithm for solving cardiac action potential models.

Science.gov (United States)

Chen, Min-Hung; Chen, Po-Yuan; Luo, Ching-Hsing

2016-10-01

An adaptive integration method is proposed for computing cardiac action potential models accurately and efficiently. Time steps are adaptively chosen by solving a quadratic formula involving the first and second derivatives of the membrane action potential. To improve the numerical accuracy, we devise an extremum-locator (el) function to predict the local extremum when approaching the peak amplitude of the action potential. In addition, the time step restriction (tsr) technique is designed to limit the increase in time steps, and thus prevent the membrane potential from changing abruptly. The performance of the proposed method is tested using the Luo-Rudy phase 1 (LR1), dynamic (LR2), and human O'Hara-Rudy dynamic (ORd) ventricular action potential models, and the Courtemanche atrial model incorporating a Markov sodium channel model. Numerical experiments demonstrate that the action potential generated using the proposed method is more accurate than that using the traditional Hybrid method, especially near the peak region. The traditional Hybrid method may choose large time steps near to the peak region, and sometimes causes the action potential to become distorted. In contrast, the proposed new method chooses very fine time steps in the peak region, but large time steps in the smooth region, and the profiles are smoother and closer to the reference solution. In the test on the stiff Markov ionic channel model, the Hybrid blows up if the allowable time step is set to be greater than 0.1ms. In contrast, our method can adjust the time step size automatically, and is stable. Overall, the proposed method is more accurate than and as efficient as the traditional Hybrid method, especially for the human ORd model. The proposed method shows improvement for action potentials with a non-smooth morphology, and it needs further investigation to determine whether the method is helpful during propagation of the action potential. Copyright © 2016 Elsevier Ltd. All rights

Calculation of stochastic broadening due to noise and field errors in the simple map in action-angle coordinates

Science.gov (United States)

Hinton, Courtney; Punjabi, Alkesh; Ali, Halima

2008-11-01

The simple map is the simplest map that has topology of divertor tokamaks [1]. Recently, the action-angle coordinates for simple map are analytically calculated, and simple map is constructed in action-angle coordinates [2]. Action-angle coordinates for simple map can not be inverted to real space coordinates (R,Z). Because there is logarithmic singularity on the ideal separatrix, trajectories can not cross separatrix [2]. Simple map in action-angle coordinates is applied to calculate stochastic broadening due to magnetic noise and field errors. Mode numbers for noise + field errors from the DIII-D tokamak are used. Mode numbers are (m,n)=(3,1), (4,1), (6,2), (7,2), (8,2), (9,3), (10,3), (11,3), (12,3) [3]. The common amplitude δ is varied from 0.8X10-5 to 2.0X10-5. For this noise and field errors, the width of stochastic layer in simple map is calculated. This work is supported by US Department of Energy grants DE-FG02-07ER54937, DE-FG02-01ER54624 and DE-FG02-04ER54793 1. A. Punjabi, H. Ali, T. Evans, and A. Boozer, Phys. Let. A 364, 140--145 (2007). 2. O. Kerwin, A. Punjabi, and H. Ali, to appear in Physics of Plasmas. 3. A. Punjabi and H. Ali, P1.012, 35^th EPS Conference on Plasma Physics, June 9-13, 2008, Hersonissos, Crete, Greece.

Cowichan Valley energy mapping and modelling. Report 1 - GIS mapping of potential renewable energy resources in the CVRD. Final report. [Vancouver Island, Canada

Energy Technology Data Exchange (ETDEWEB)

NONE

2012-06-15

The driving force behind the Integrated Energy Mapping and Analysis project was the identification and analysis of a suite of pathways that the Cowichan Valley Regional District (CVRD) can utilise to increase its energy resilience, as well as reduce energy consumption and GHG emissions, with a primary focus on the residential sector. Mapping and analysis undertaken will support provincial energy and GHG reduction targets, and the suite of pathways outlined will address a CVRD internal target that calls for 75% of the region's energy within the residential sector to come from locally sourced renewables by 2050. The target has been developed as a mechanism to meet resilience and climate action target. The maps and findings produced are to be integrated as part of a regional policy framework currently under development. The first task in the project was the production of a series of thematic GIS maps and associated databases of potential renewable energy resources in the CVRD. The renewable energy sources mapped were solar, wind, micro hydro, and biomass (residues and waste). Other sources were also discussed (e.g. geothermal heat) but not mapped due to lack of spatially explicit input data. The task 1 findings are detailed in this report. (LN)

Methodology developed to make the Quebec indoor radon potential map

Energy Technology Data Exchange (ETDEWEB)

Drolet, Jean-Philippe, E-mail: jean-philippe.drolet@ete.inrs.ca [Institut national de la recherche scientifique, Eau Terre Environnement Research Centre (ETE-INRS), 490 de la Couronne, G1K 9A9 Quebec (Canada); Martel, Richard [Institut national de la recherche scientifique, Eau Terre Environnement Research Centre (ETE-INRS), 490 de la Couronne, G1K 9A9 Quebec (Canada); Poulin, Patrick [Institut national de santé publique du Québec (INSPQ), 945 avenue Wolfe, G1V 5B3 Quebec (Canada); Dessau, Jean-Claude [Agence de la santé et des services sociaux des Laurentides, 1000 rue Labelle, J7Z 5 N6 Saint-Jérome (Canada)

2014-03-01

This paper presents a relevant approach to predict the indoor radon potential based on the combination of the radiogeochemical data and the indoor radon measurements in the Quebec province territory (Canada). The Quebec ministry of health asked for such a map to identify the radon-prone areas to manage the risk for the population related to indoor radon exposure. Three radiogeochemical criteria including (1) equivalent uranium (eU) concentration from airborne surface gamma-ray surveys, (2) uranium concentration measurements in sediments, (3) bedrock and surficial geology were combined with 3082 basement radon concentration measurements to identify the radon-prone areas. It was shown that it is possible to determine thresholds for the three criteria that implied statistically significant different levels of radon potential using Kruskal–Wallis one way analyses of variance by ranks. The three discretized radiogeochemical datasets were combined into a total predicted radon potential that sampled 98% of the studied area. The combination process was also based on Kruskal–Wallis one way ANOVA. Four statistically significant different predicted radon potential levels were created: low, medium, high and very high. Respectively 10 and 13% of the dwellings exceed the Canadian radon guideline of 200 Bq/m{sup 3} in low and medium predicted radon potentials. These proportions rise up to 22 and 45% respectively for high and very high predicted radon potentials. This predictive map of indoor radon potential based on the radiogeochemical data was validated using a map of confirmed radon exposure in homes based on the basement radon measurements. It was shown that the map of predicted radon potential based on the radiogeochemical data was reliable to identify radon-prone areas even in zones where no indoor radon measurement exists. - Highlights: • 5 radiogeochemical datasets were used to map the geogenic indoor radon potential. • An indoor radon potential was determined for

Modeling of action potential generation in NG108-15 cells.

Science.gov (United States)

Molnar, Peter; Hickman, James J

2014-01-01

In order to explore the possibility of identifying toxins based on their effect on the shape of action potentials, we created a computer model of the action potential generation in NG108-15 cells (a neuroblastoma/glioma hybrid cell line). To generate the experimental data for model validation, voltage-dependent sodium, potassium and high-threshold calcium currents, as well as action potentials, were recorded from NG108-15 cells with conventional whole-cell patch-clamp methods. Based on the classic Hodgkin-Huxley formalism and the linear thermodynamic description of the rate constants, ion-channel parameters were estimated using an automatic fitting method. Utilizing the established parameters, action potentials were generated using the Hodgkin-Huxley formalism and were fitted to the recorded action potentials. To demonstrate the applicability of the method for toxin detection and discrimination, the effect of tetrodotoxin (a sodium channel blocker) and tefluthrin (a pyrethroid that is a sodium channel opener) were studied. The two toxins affected the shape of the action potentials differently, and their respective effects were identified based on the predicted changes in the fitted parameters.

Spatial mapping of renewable energy potential

Energy Technology Data Exchange (ETDEWEB)

Ramachandra, T.V. [Centre for Sustainable Technologies, Indian Institute of Science, Bangalore (India); Energy Research Group, CES RNO 215, Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560 012 (India); Shruthi, B.V. [Energy Research Group, CES RNO 215, Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560 012 (India)

2007-09-15

An energy resource that is renewed by nature and whose supply is not affected by the rate of consumption is often termed as renewable energy. The need to search for renewable, alternate and non-polluting sources of energy assumes top priority for self-reliance in the regional energy supply. This demands an estimation of available energy resources spatially to evolve better management strategies for ensuring sustainability of resources. The spatial mapping of availability and demand of energy resources would help in the integrated regional energy planning through an appropriate energy supply-demand matching. This paper discusses the application of Geographical Information System (GIS) to map the renewable energy potential talukwise in Karnataka State, India. Taluk is an administrative division in the federal set-up in India to implement developmental programmes like dissemination of biogas, improved stoves, etc. Hence, this paper focuses talukwise mapping of renewable energy (solar, wind, bioenergy and small hydroenergy) potential for Karnataka using GIS. GIS helps in spatial and temporal analyses of the resources and demand and also aids as Decision Support System while implementing location-specific renewable energy technologies. Regions suitable for tapping solar energy are mapped based on global solar radiation data, which provides a picture of the potential. Coastal taluks in Uttara Kannada have higher global solar radiation during summer (6.31 kWh/m{sup 2}), monsoon (4.16 kWh/m{sup 2}) and winter (5.48 kWh/m{sup 2}). Mapping of regions suitable for tapping wind energy has been done based on wind velocity data, and it shows that Chikkodi taluk, Belgaum district, has higher potential during summer (6.06 m/s), monsoon (8.27 m/s) and winter (5.19 m/s). Mysore district has the maximum number of small hydropower plants with a capacity of 36 MW. Talukwise computation of bioenergy availability from agricultural residue, forest, horticulture, plantation and livestock

Dual Axis Radiographic Hydrodynamic Test Facility mitigation action plan. Annual report for 1997

Energy Technology Data Exchange (ETDEWEB)

Haagenstad, H.T.

1998-01-15

This Mitigation Action Plan Annual Report (MAPAR) has been prepared by the US Department of Energy (DOE) as part of implementing the Dual Axis Radiographic Hydrodynamic Test Facility (DARHT) Mitigation Action Plan (MAP). This MAPAR provides a status on specific DARHT facility design- and construction-related mitigation actions that have been initiated in order to fulfill DOE`s commitments under the DARHT MAP. The functions of the DARHT MAP are to (1) document potentially adverse environmental impacts of the Phased Containment Option delineated in the Final EIS, (2) identify commitments made in the Final EIS and ROD to mitigate those potential impacts, and (3) establish Action Plans to carry out each commitment (DOE 1996). The DARHT MAP is divided into eight sections. Sections 1--5 provide background information regarding the NEPA review of the DARHT project and an introduction to the associated MAP. Section 6 references the Mitigation Action Summary Table which summaries the potential impacts and mitigation measures; indicates whether the mitigation is design-, construction-, or operational-related; the organization responsible for the mitigation measure; and the projected or actual completion data for each mitigation measure. Sections 7 and 8 discuss the Mitigation Action Plan Annual Report and Tracking System commitment and the Potential Impacts, Commitments, and Action Plans respectively. Under Section 8, potential impacts are categorized into five areas of concern: General Environment, including impacts to air and water; Soils, especially impacts affecting soil loss and contamination; Biotic Resources, especially impacts affecting threatened and endangered species; Cultural/Paleontological Resources, especially impacts affecting the archeological site known as Nake`muu; and Human Health and Safety, especially impacts pertaining to noise and radiation. Each potential impact includes a brief statement of the nature of the impact and its cause(s). The commitment

A physical action potential generator: design, implementation and evaluation.

Science.gov (United States)

Latorre, Malcolm A; Chan, Adrian D C; Wårdell, Karin

2015-01-01

The objective was to develop a physical action potential generator (Paxon) with the ability to generate a stable, repeatable, programmable, and physiological-like action potential. The Paxon has an equivalent of 40 nodes of Ranvier that were mimicked using resin embedded gold wires (Ø = 20 μm). These nodes were software controlled and the action potentials were initiated by a start trigger. Clinically used Ag-AgCl electrodes were coupled to the Paxon for functional testing. The Paxon's action potential parameters were tunable using a second order mathematical equation to generate physiologically relevant output, which was accomplished by varying the number of nodes involved (1-40 in incremental steps of 1) and the node drive potential (0-2.8 V in 0.7 mV steps), while keeping a fixed inter-nodal timing and test electrode configuration. A system noise floor of 0.07 ± 0.01 μV was calculated over 50 runs. A differential test electrode recorded a peak positive amplitude of 1.5 ± 0.05 mV (gain of 40x) at time 196.4 ± 0.06 ms, including a post trigger delay. The Paxon's programmable action potential like signal has the possibility to be used as a validation test platform for medical surface electrodes and their attached systems.

Sympathetic Nervous Regulation of Calcium and Action Potential Alternans in the Intact Heart.

Science.gov (United States)

Winter, James; Bishop, Martin J; Wilder, Catherine D E; O'Shea, Christopher; Pavlovic, Davor; Shattock, Michael J

2018-01-01

Rationale: Arrhythmogenic cardiac alternans are thought to be an important determinant for the initiation of ventricular fibrillation. There is limited information on the effects of sympathetic nerve stimulation (SNS) on alternans in the intact heart and the conclusions of existing studies, focused on investigating electrical alternans, are conflicted. Meanwhile, several lines of evidence implicate instabilities in Ca handling, not electrical restitution, as the primary mechanism underpinning alternans. Despite this, there have been no studies on Ca alternans and SNS in the intact heart. The present study sought to address this, by application of voltage and Ca optical mapping for the simultaneous study of APD and Ca alternans in the intact guinea pig heart during direct SNS. Objective : To determine the effects of SNS on APD and Ca alternans in the intact guinea pig heart and to examine the mechanism(s) by which the effects of SNS are mediated. Methods and Results : Studies utilized simultaneous voltage and Ca optical mapping in isolated guinea pig hearts with intact innervation. Alternans were induced using a rapid dynamic pacing protocol. SNS was associated with rate-independent shortening of action potential duration (APD) and the suppression of APD and Ca alternans, as indicated by a shift in the alternans threshold to faster pacing rates. Qualitatively similar results were observed with exogenous noradrenaline perfusion. In contrast with previous reports, both SNS and noradrenaline acted to flatten the slope of the electrical restitution curve. Pharmacological block of the slow delayed rectifying potassium current (I Ks ), sufficient to abolish I Ks -mediated APD-adaptation, partially reversed the effects of SNS on pacing-induced alternans. Treatment with cyclopiazonic acid, an inhibitor of the sarco(endo)plasmic reticulum ATPase, had opposite effects to that of SNS, acting to increase susceptibility to alternans, and suggesting that accelerated Ca reuptake

Object-action dissociation: A voxel-based lesion-symptom mapping study on 102 patients after glioma removal

Directory of Open Access Journals (Sweden)

Alberto Pisoni

Full Text Available Data concerning the neural basis of noun and verb processing are inconsistent. Some authors assume that action-verb processing is based on frontal areas while nouns processing relies on temporal regions; others argue that the circuits processing verbs and nouns are closely interconnected in a predominantly left-lateralized fronto-temporal-parietal network; yet, other researchers consider that the primary motor cortex plays a crucial role in processing action verbs. In the present study, one hundred and two patients with a tumour either in the right or left hemisphere were submitted to picture naming of objects and actions before and after surgery. To test the effect of specific brain regions in object and action naming, patients' lesions were mapped and voxel-lesion-symptom mapping (VLSM was computed. Behavioural results showed that left-brain damaged patients were significantly more impaired than right brain-damaged patients. The VLSM showed that these two grammatical classes are segregated in the left hemisphere. In particular, scores in naming of objects correlated with damage to the anterior temporal region, while scores in naming of actions correlated with lesions in the parietal areas and in the posterior temporal cortex. In addition, VLSM analyses carried out on non-linguistic tasks were not significant, confirming that the regions associated with deficits in object and action naming were not generally engaged in all cognitive tasks. Finally, the involvement of subcortical pathways was investigated and the inferior longitudinal fasciculus proved to play a role in object naming, while no specific bundle was identified for actions. Keywords: Object action dissociation, Temporal lesion, Frontal lesion, Voxel-based lesion symptom mapping

Dam break analysis and flood inundation map of Krisak dam for emergency action plan

Science.gov (United States)

Juliastuti, Setyandito, Oki

2017-11-01

The Indonesian Regulation which refers to the ICOLD Regulation (International Committee on Large Dam required have the Emergency Action Plan (EAP) guidelines because of the dams have potential failure. In EAP guidelines there is a management of evacuation where the determination of the inundation map based on flood modeling. The purpose of the EAP is to minimize the risk of loss of life and property in downstream which caused by dam failure. This paper will describe about develop flood modeling and inundation map in Krisak dam using numerical methods through dam break analysis (DBA) using hydraulic model Zhong Xing HY-21. The approaches of dam failure simulation are overtopping and piping. Overtopping simulation based on quadrangular, triangular and trapezium fracture. Piping simulation based on cracks of orifice. Using results of DBA, hazard classification of Krisak dam is very high. The nearest village affected dam failure is Singodutan village (distance is 1.45 kilometer from dam) with inundation depth is 1.85 meter. This result can be used by stakeholders such as emergency responders and the community at risk in formulating evacuation procedure.

A novel approach to dual excitation ratiometric optical mapping of cardiac action potentials with di-4-ANEPPS using pulsed LED excitation.

Science.gov (United States)

Bachtel, Andrew D; Gray, Richard A; Stohlman, Jayna M; Bourgeois, Elliot B; Pollard, Andrew E; Rogers, Jack M

2011-07-01

We developed a new method for ratiometric optical mapping of transmembrane potential (V(m)) in cardiac preparations stained with di-4-ANEPPS. V(m)-dependent shifts of excitation and emission spectra establish two excitation bands (481 nm) that produce fluorescence changes of opposite polarity within a single emission band (575-620 nm). The ratio of these positive and negative fluorescence signals (excitation ratiometry) increases V(m) sensitivity and removes artifacts common to both signals. We pulsed blue (450 ± 10 nm) and cyan (505 ± 15 nm) light emitting diodes (LEDs) at 375 Hz in alternating phase synchronized to a camera (750 frames-per-second). Fluorescence was bandpass filtered (585 ± 20 nm). This produced signals with upright (blue) and inverted (cyan) action potentials (APs) interleaved in sequential frames. In four whole swine hearts with motion chemically arrested, fractional fluorescence for blue, cyan, and ratio signals was 1.2 ± 0.3%, 1.2 ± 0.3%, and 2.4 ± 0.6%, respectively. Signal-to-noise ratios were 4.3 ± 1.4, 4.0 ± 1.2, and 5.8 ± 1.9, respectively. After washing out the electromechanical uncoupling agent, we characterized motion artifact by cross-correlating blue, cyan, and ratio signals with a signal with normal AP morphology. Ratiometry improved cross-correlation coefficients from 0.50 ± 0.48 to 0.81 ± 0.25, but did not cancel all motion artifacts. These findings demonstrate the feasibility of pulsed LED excitation ratiometry in myocardium. © 2011 IEEE

Atlas of the Colombian coal, Potential map and rank: Map 5-09

International Nuclear Information System (INIS)

Pulido Gonzalez, Orlando

1999-01-01

With the presentation of the Atlas of Coal to scale 1:500.000, it is sought to show to big features the location of the different areas with coal in Colombia, associating with the geologic units, the potential and the range. In the Map 5-09, the formations that include the coal are defined as Umir, Guaduas, Limbo, (Los Cuervos), San Fernando, (Carbonera), defined as Kst, Ksgt and Pgt. For the potential an arbitrary scale settled down, in the following way: in the first place bigger to 1000 million tons; between 1000 and 100; between 100 and 10 and lastly smaller to 10 million tons. These figures are represented in the map by triangles with colors that they are equal before to the figures mentioned. Keeping in mind the scale, it was opted to report the potential in the category of the hypothetical resources; when the resources or reserves are established, they are also reported. As for the range, in the map it is indicated by means of symbols that should be taken as a domain or tendency of the coal in each area in general. The the coal rank understood as the transformation that has reached along the geologic evolution is what is mentioned as anthracitic coal, semi-anthracitic, bituminous low in volatile, bituminous middle in volatile, bituminous high in volatile A, B and C, sub-bituminous and lastly the lignite. For each map are mentioned that there are determined

Mapping severe fire potential across the contiguous United States

Science.gov (United States)

Brett H. Davis

2016-01-01

The Fire Severity Mapping System (FIRESEV) project is an effort to provide critical information and tools to fire managers that enhance their ability to assess potential ecological effects of wildland fire. A major component of FIRESEV is the development of a Severe Fire Potential Map (SFPM), a geographic dataset covering the contiguous United States (CONUS) that...

Components of action potential repolarization in cerebellar parallel fibres.

Science.gov (United States)

Pekala, Dobromila; Baginskas, Armantas; Szkudlarek, Hanna J; Raastad, Morten

2014-11-15

Repolarization of the presynaptic action potential is essential for transmitter release, excitability and energy expenditure. Little is known about repolarization in thin, unmyelinated axons forming en passant synapses, which represent the most common type of axons in the mammalian brain's grey matter.We used rat cerebellar parallel fibres, an example of typical grey matter axons, to investigate the effects of K(+) channel blockers on repolarization. We show that repolarization is composed of a fast tetraethylammonium (TEA)-sensitive component, determining the width and amplitude of the spike, and a slow margatoxin (MgTX)-sensitive depolarized after-potential (DAP). These two components could be recorded at the granule cell soma as antidromic action potentials and from the axons with a newly developed miniaturized grease-gap method. A considerable proportion of fast repolarization remained in the presence of TEA, MgTX, or both. This residual was abolished by the addition of quinine. The importance of proper control of fast repolarization was demonstrated by somatic recordings of antidromic action potentials. In these experiments, the relatively broad K(+) channel blocker 4-aminopyridine reduced the fast repolarization, resulting in bursts of action potentials forming on top of the DAP. We conclude that repolarization of the action potential in parallel fibres is supported by at least three groups of K(+) channels. Differences in their temporal profiles allow relatively independent control of the spike and the DAP, whereas overlap of their temporal profiles provides robust control of axonal bursting properties.

[Loudness optimized registration of compound action potential in cochlear implant recipients].

Science.gov (United States)

Berger, Klaus; Hocke, Thomas; Hessel, Horst

2017-11-01

Background Postoperative measurements of compound action potentials are not always possible due to the insufficient acceptance of the CI-recipients. This study investigated the impact of different parameters on the acceptance of the measurements. Methods Compound action potentials of 16 CI recipients were measured with different pulse-widths. Recipients performed a loudness rating at the potential thresholds with the different sequences. Results Compound action potentials obtained with higher pulse-widths were rated softer than those obtained with smaller pulse-widths. Conclusions Compound action potentials measured with higher pulse-widths generate a gap between loudest acceptable presentation level and potential threshold. This gap contributes to a higher acceptance of postoperative measurements. Georg Thieme Verlag KG Stuttgart · New York.

Studies on the Action Potential From a Thermodynamic Perspective

DEFF Research Database (Denmark)

Wang, Tian

and nerves with ganglia. (2) Attempts have been made to measure the temperature change associated with an action potential as well as an oscillation reaction (Briggs-Rauscher reaction) that shares the adiabatic feature. It turns out that some practical issues need to be solved for the temperature measurement...... of the nerve impulses, while the measured temperature change during the oscillation reaction suggests that there are a reversible adiabatic process and a dissipative process. (3) Local anesthetic e↵ect on nerves is studied. Local anesthetic lidocaine causes a significant stimulus threshold shift of the action......Nerve impulse, also called action potential, has mostly been considered as a pure electrical phenomenon. However, changes in dimensions, e.g. thickness and length, and in temperature along with action potentials have been observed, which indicates that the nerve is a thermodynamic system. The work...

Wireless cardiac action potential transmission with ultrasonically inserted silicon microprobes

International Nuclear Information System (INIS)

Shen, C J; Ramkumar, A; Lal, A; Gilmour, R F Jr

2011-01-01

This paper reports on the integration of ultrasonically inserted horn-shaped cardiac probes with wireless transmission of 3D cardiac action potential measurement for applications in ex vivo preparations such as monitoring the onset of ventricular fibrillation. Ultrasonically inserted silicon horn probes permit reduced penetration force during insertion, allowing silicon, a brittle material, to penetrate cardiac tissue. The probes also allow recording from multiple sites that are lithographically defined. An application-specific integrated circuit has been designed with a 40 dB amplifying stage and a frequency modulating oscillator at 95 MHz to wirelessly transmit the recorded action potentials. This ultrasonically inserted microprobe wireless system demonstrates the initial results in wireless monitoring of 3D action potential propagation, and the extraction of parameters of interest including the action potential duration and diastolic interval

Numerical investigation of action potential transmission in plants

Directory of Open Access Journals (Sweden)

Mariusz Pietruszka

2014-01-01

Full Text Available In context of a fairly concise review of recent literature and well established experimental results we reconsider the problem of action potential propagating steadily down the plant cell(s. Having adopted slightly modified Hodgkin-Huxley set of differential equations for the action potential we carried out the numerical investigation of these equations in the course of time. We argue that the Hodgkin-Huxley-Katz model for the nerve impulse can be used to describe the phenomena which take place in plants - this point of view seems to be plausible since the mechanisms involving active ionic transport across membranes from the mathematical point of view are similar. Besides, we compare in a qualitative way our theoretical outcomes with typical experimental results for the action potentials which arise as the reaction of plants to electrical, mechanical and light stimuli. Moreover, we point out the relevance of the sequence of events during the pulse with the appropriate ionic fluxes.

Perturbation analysis of spontaneous action potential initiation by stochastic ion channels

KAUST Repository

Keener, James P.; Newby, Jay M.

2011-01-01

A stochastic interpretation of spontaneous action potential initiation is developed for the Morris-Lecar equations. Initiation of a spontaneous action potential can be interpreted as the escape from one of the wells of a double well potential

State and location dependence of action potential metabolic cost in cortical pyramidal neurons.

Science.gov (United States)

Hallermann, Stefan; de Kock, Christiaan P J; Stuart, Greg J; Kole, Maarten H P

2012-06-03

Action potential generation and conduction requires large quantities of energy to restore Na(+) and K(+) ion gradients. We investigated the subcellular location and voltage dependence of this metabolic cost in rat neocortical pyramidal neurons. Using Na(+)/K(+) charge overlap as a measure of action potential energy efficiency, we found that action potential initiation in the axon initial segment (AIS) and forward propagation into the axon were energetically inefficient, depending on the resting membrane potential. In contrast, action potential backpropagation into dendrites was efficient. Computer simulations predicted that, although the AIS and nodes of Ranvier had the highest metabolic cost per membrane area, action potential backpropagation into the dendrites and forward propagation into axon collaterals dominated energy consumption in cortical pyramidal neurons. Finally, we found that the high metabolic cost of action potential initiation and propagation down the axon is a trade-off between energy minimization and maximization of the conduction reliability of high-frequency action potentials.

Active action potential propagation but not initiation in thalamic interneuron dendrites

Science.gov (United States)

Casale, Amanda E.; McCormick, David A.

2012-01-01

Inhibitory interneurons of the dorsal lateral geniculate nucleus of the thalamus modulate the activity of thalamocortical cells in response to excitatory input through the release of inhibitory neurotransmitter from both axons and dendrites. The exact mechanisms by which release can occur from dendrites are, however, not well understood. Recent experiments using calcium imaging have suggested that Na/K based action potentials can evoke calcium transients in dendrites via local active conductances, making the back-propagating action potential a candidate for dendritic neurotransmitter release. In this study, we employed high temporal and spatial resolution voltage-sensitive dye imaging to assess the characteristics of dendritic voltage deflections in response to Na/K action potentials in interneurons of the mouse dorsal lateral geniculate nucleus. We found that trains or single action potentials elicited by somatic current injection or local synaptic stimulation led to action potentials that rapidly and actively back-propagated throughout the entire dendritic arbor and into the fine filiform dendritic appendages known to release GABAergic vesicles. Action potentials always appeared first in the soma or proximal dendrite in response to somatic current injection or local synaptic stimulation, and the rapid back-propagation into the dendritic arbor depended upon voltage-gated sodium and TEA-sensitive potassium channels. Our results indicate that thalamic interneuron dendrites integrate synaptic inputs that initiate action potentials, most likely in the axon initial segment, that then back-propagate with high-fidelity into the dendrites, resulting in a nearly synchronous release of GABA from both axonal and dendritic compartments. PMID:22171033

[Effect of pulse magnetic field on distribution of neuronal action potential].

Science.gov (United States)

Zheng, Yu; Cai, Di; Wang, Jin-Hai; Li, Gang; Lin, Ling

2014-08-25

The biological effect on the organism generated by magnetic field is widely studied. The present study was aimed to observe the change of sodium channel under magnetic field in neurons. Cortical neurons of Kunming mice were isolated, subjected to 15 Hz, 1 mT pulse magnetic stimulation, and then the currents of neurons were recorded by whole-cell patch clamp. The results showed that, under magnetic stimulation, the activation process of Na(+) channel was delayed, and the inactivation process was accelerated. Given the classic three-layer model, the polarization diagram of cell membrane potential distribution under pulse magnetic field was simulated, and it was found that the membrane potential induced was associated with the frequency and intensity of magnetic field. Also the effect of magnetic field-induced current on action potential was simulated by Hodgkin-Huxley (H-H) model. The result showed that the generation of action potential was delayed, and frequency and the amplitudes were decreased when working current was between -1.32 μA and 0 μA. When the working current was higher than 0 μA, the generation frequency of action potential was increased, and the change of amplitudes was not obvious, and when the working current was lower than -1.32 μA, the time of rising edge and amplitudes of action potential were decreased drastically, and the action potential was unable to generate. These results suggest that the magnetic field simulation can affect the distribution frequency and amplitude of action potential of neuron via sodium channel mediation.

ECOLOGICAL CLASSIFICATION OF LAND AND ECOSYSTEM MAPPING. TOWARDS THE IMPLEMENTATION OF ACTION 5 OF THE EUROPEAN BIODIVERSITY STRATEGY TO 2020 IN ITALY.

Directory of Open Access Journals (Sweden)

G. Capotorti

2014-04-01

Full Text Available The aim of the present paper is to illustrate the basic data and the methodological approach proposed for the implementation of Action 5 of the European Biodiversity Strategy in Italy. In particular, it focuses on a model for ecosystem mapping and characterisation at the country level that has been built with the interdisciplinary involvement of geobotanists, functional ecologists, forest scientists and zoologists. The first operational steps of the model are based on the cartographic integration between potential natural vegetation, biogeographic regions, and land cover maps. The final step entails characterising the mapped ecosystems in terms of Habitats Directive, local occurrence of threatened plant species and faunal components. The model is going to be tested in Italy, but should also be applied elsewhere in Mediterranean Europe, especially in those countries that have a comparable ecological complexity.

A case study for the integration of predictive mineral potential maps

Science.gov (United States)

Lee, Saro; Oh, Hyun-Joo; Heo, Chul-Ho; Park, Inhye

2014-09-01

This study aims to elaborate on the mineral potential maps using various models and verify the accuracy for the epithermal gold (Au) — silver (Ag) deposits in a Geographic Information System (GIS) environment assuming that all deposits shared a common genesis. The maps of potential Au and Ag deposits were produced by geological data in Taebaeksan mineralized area, Korea. The methodological framework consists of three main steps: 1) identification of spatial relationships 2) quantification of such relationships and 3) combination of multiple quantified relationships. A spatial database containing 46 Au-Ag deposits was constructed using GIS. The spatial association between training deposits and 26 related factors were identified and quantified by probabilistic and statistical modelling. The mineral potential maps were generated by integrating all factors using the overlay method and recombined afterwards using the likelihood ratio model. They were verified by comparison with test mineral deposit locations. The verification revealed that the combined mineral potential map had the greatest accuracy (83.97%), whereas it was 72.24%, 65.85%, 72.23% and 71.02% for the likelihood ratio, weight of evidence, logistic regression and artificial neural network models, respectively. The mineral potential map can provide useful information for the mineral resource development.

Dynamics of action potential initiation in the GABAergic thalamic reticular nucleus in vivo.

Science.gov (United States)

Muñoz, Fabián; Fuentealba, Pablo

2012-01-01

Understanding the neural mechanisms of action potential generation is critical to establish the way neural circuits generate and coordinate activity. Accordingly, we investigated the dynamics of action potential initiation in the GABAergic thalamic reticular nucleus (TRN) using in vivo intracellular recordings in cats in order to preserve anatomically-intact axo-dendritic distributions and naturally-occurring spatiotemporal patterns of synaptic activity in this structure that regulates the thalamic relay to neocortex. We found a wide operational range of voltage thresholds for action potentials, mostly due to intrinsic voltage-gated conductances and not synaptic activity driven by network oscillations. Varying levels of synchronous synaptic inputs produced fast rates of membrane potential depolarization preceding the action potential onset that were associated with lower thresholds and increased excitability, consistent with TRN neurons performing as coincidence detectors. On the other hand the presence of action potentials preceding any given spike was associated with more depolarized thresholds. The phase-plane trajectory of the action potential showed somato-dendritic propagation, but no obvious axon initial segment component, prominent in other neuronal classes and allegedly responsible for the high onset speed. Overall, our results suggest that TRN neurons could flexibly integrate synaptic inputs to discharge action potentials over wide voltage ranges, and perform as coincidence detectors and temporal integrators, supported by a dynamic action potential threshold.

Design of a noise action plan based on a road traffic noise map

NARCIS (Netherlands)

Ausejo, M.; Tabacchi, M.; Recuero, M.; Asensio, C.; Pagan Munoz, R.; Pavón, I.

2011-01-01

According to European Directive 2002/49/CE, EU state members had to compile a strategic noise map no later than 30 June 2007 and a corresponding action plan no later than 18 July 2008 for all agglomerations with more than 250,000 inhabitants and for all major airports, roads and railways. A study on

Setting strategy for system change: using concept mapping to prioritise national action for chronic disease prevention.

Science.gov (United States)

Wutzke, Sonia; Roberts, Nick; Willis, Cameron; Best, Allan; Wilson, Andrew; Trochim, William

2017-08-08

Chronic diseases are a serious and urgent problem, requiring at-scale, multi-component, multi-stakeholder action and cooperation. Despite numerous national frameworks and agenda-setting documents to coordinate prevention efforts, Australia, like many countries internationally, is yet to substantively impact the burden from chronic disease. Improved evidence on effective strategies for the prevention of chronic disease is required. This research sought to articulate a priority set of important and feasible action domains to inform future discussion and debate regarding priority areas for chronic disease prevention policy and strategy. Using concept mapping, a mixed-methods approach to making use of the best available tacit knowledge of recognised, diverse and well-experienced actors, and national actions to improve the prevention of chronic disease in Australia were identified and then mapped. Participants (ranging from 58 to 78 in the various stages of the research) included a national sample of academics, policymakers and practitioners. Data collection involved the generation and sorting of statements by participants. A series of visual representations of the data were then developed. A total of 95 statements were distilled into 12 clusters for action, namely Inter-Sectoral Partnerships; Systems Perspective/Action; Governance; Roles and Responsibilities; Evidence, Feedback and Learning; Funding and Incentive; Creating Demand; Primary Prevention; Social Determinants and Equity; Healthy Environments; Food and Nutrition; and Regulation and Policy. Specific areas for more immediate national action included refocusing the health system to prevention over cure, raising the profile of public health with health decision-makers, funding policy- and practice-relevant research, improving communication about prevention, learning from both global best-practice and domestic successes and failures, increasing the focus on primary prevention, and developing a long-term prevention

The DBI action, higher-derivative supergravity, and flattening inflaton potentials

International Nuclear Information System (INIS)

Bielleman, Sjoerd; Ibáñez, Luis E.; Pedro, Francisco G.; Valenzuela, Irene; Wieck, Clemens

2016-01-01

In string theory compactifications it is common to find an effective Lagrangian for the scalar fields with a non-canonical kinetic term. We study the effective action of the scalar position moduli of Type II Dp-branes. In many instances the kinetic terms are in fact modified by a term proportional to the scalar potential itself. This can be linked to the appearance of higher-dimensional supersymmetric operators correcting the Kähler potential. We identify the supersymmetric dimension-eight operators describing the α"′ corrections captured by the D-brane Dirac-Born-Infeld action. Our analysis then allows an embedding of the D-brane moduli effective action into an N=1 supergravity formulation. The effects of the potential-dependent kinetic terms may be very important if one of the scalars is the inflaton, since they lead to a flattening of the scalar potential. We analyze this flattening effect in detail and compute its impact on the CMB observables for single-field inflation with monomial potentials.

Effect of an educational game on university students' learning about action potentials.

Science.gov (United States)

Luchi, Kelly Cristina Gaviao; Montrezor, Luís Henrique; Marcondes, Fernanda K

2017-06-01

The aim of this study was to evaluate the effect of an educational game that is used for teaching the mechanisms of the action potentials in cell membranes. The game was composed of pieces representing the intracellular and extracellular environments, ions, ion channels, and the Na + -K + -ATPase pump. During the game activity, the students arranged the pieces to demonstrate how the ions move through the membrane in a resting state and during an action potential, linking the ion movement with a graph of the action potential. To test the effect of the game activity on student understanding, first-year dental students were given the game to play at different times in a series of classes teaching resting membrane potential and action potentials. In all experiments, students who played the game performed better in assessments. According to 98% of the students, the game supported the learning process. The data confirm the students' perception, indicating that the educational game improved their understanding about action potentials. Copyright © 2017 the American Physiological Society.

Mapping Irrigation Potential in the Upper East Region of Ghana

Science.gov (United States)

Akomeah, E.; Odai, S. N.; Annor, F. O.; Adjei, K. A.; Barry, B.

2009-04-01

The Upper East Region together with the other two regions in Northern Ghana (Upper West and Northern Region) is seen as the locus of perennial food deficit (GPRS, 2003). Despite, the provision of over 200 small scale dams and various mechanisms aimed at poverty alleviation, the region is still plagued with poverty and yearly food shortages. To achieve food security and alleviate poverty in the region however, modernization of agriculture through irrigation is deemed inevitable. While it is true that considerable potential still exists for future expansion of irrigation, it cannot be refuted that water is becoming scarcer in the regions where the need for irrigation is most important, hence mapping the irrigation potential of the region will be the first step toward ensuring sound planning and sustainability of the irrigation developments. In this study, an attempt has been made to map out the irrigation potential of the Upper East Region. The river basin approach was used in assessing the irrigation potential. The catchments drained by The White Volta river, Red volta river, River Sissili and River Kulpawn were considered in the assessment. The irrigation potential for the sub basins was computed by combining information on gross irrigation water requirements for the selected cash crops, area of soil suitable for irrigation and available water resources. The capacity of 80%, 70%, 60% and 50% time of exceedance flow of the available surface water resources in the respective sub basins was estimated. The area that can be irrigated with this flow was computed with selected cropping pattern. Combining the results of the potential irrigable areas and the land use map of the respective sub basins, an irrigation potential map has been generated showing potential sites in the upper east region that can be brought under irrigation. Keywords: Irrigation potential, irrigation water requirement, land evaluation, dependable flow

Mapping VIPS concepts for nursing interventions to the ISO reference terminology model for nursing actions: A collaborative Scandinavian analysis

DEFF Research Database (Denmark)

Ehnfors, Margareta; Angermo, Lilly Marit; Berring, Lene

2006-01-01

analyzed the VIPS model's concepts for nursing interventions using prototypical examples of nursing actions, involving 233 units of analyses, and collaborated in mapping the two models. All nursing interventions in the VIPS model comprise actions and targets, but a few lack explicit expressions of means......The aims of this study were to analyze the coherence between the concepts for nursing interventions in the Swedish VIPS model for nursing recording and the ISO Reference Terminology Model for Nursing Actions and to identify areas in the two models for further development. Seven Scandinavian experts....... In most cases, the recipient of care is implicit. Expressions for the aim of an action are absent from the ISO model. By this mapping we identified areas for future development of the VIPS model and the experience from nursing terminology work in Scandinavia can contribute to the international...

Inducing repetitive action potential firing in neurons via synthesized photoresponsive nanoscale cellular prostheses.

Science.gov (United States)

Lu, Siyuan; Madhukar, Anupam

2013-02-01

Recently we reported an analysis that examined the potential of synthesized photovoltaic functional abiotic nanosystems (PVFANs) to modulate membrane potential and activate action potential firing in neurons. Here we extend the analysis to delineate the requirements on the electronic energy levels and the attendant photophysical properties of the PVFANs to induce repetitive action potential under continuous light, a capability essential for the proposed potential application of PVFANs as retinal cellular prostheses to compensate for loss of photoreceptors. We find that repetitive action potential firing demands two basic characteristics in the electronic response of the PVFANs: an exponential dependence of the PVFAN excited state decay rate on the membrane potential and a three-state system such that, following photon absorption, the electron decay from the excited state to the ground state is via intermediate state(s) whose lifetime is comparable to the refractory time following an action potential. In this study, the potential of synthetic photovoltaic functional abiotic nanosystems (PVFANs) is examined under continuous light to modulate membrane potential and activate action potential firing in neurons with the proposed potential application of PVFANs as retinal cellular prostheses. Copyright © 2013 Elsevier Inc. All rights reserved.

A phantom axon setup for validating models of action potential recordings.

Science.gov (United States)

Rossel, Olivier; Soulier, Fabien; Bernard, Serge; Guiraud, David; Cathébras, Guy

2016-08-01

Electrode designs and strategies for electroneurogram recordings are often tested first by computer simulations and then by animal models, but they are rarely implanted for long-term evaluation in humans. The models show that the amplitude of the potential at the surface of an axon is higher in front of the nodes of Ranvier than at the internodes; however, this has not been investigated through in vivo measurements. An original experimental method is presented to emulate a single fiber action potential in an infinite conductive volume, allowing the potential of an axon to be recorded at both the nodes of Ranvier and the internodes, for a wide range of electrode-to-fiber radial distances. The paper particularly investigates the differences in the action potential amplitude along the longitudinal axis of an axon. At a short radial distance, the action potential amplitude measured in front of a node of Ranvier is two times larger than in the middle of two nodes. Moreover, farther from the phantom axon, the measured action potential amplitude is almost constant along the longitudinal axis. The results of this new method confirm the computer simulations, with a correlation of 97.6 %.

Minocycline inhibits D-amphetamine-elicited action potential bursts in a central snail neuron.

Science.gov (United States)

Chen, Y-H; Lin, P-L; Wong, R-W; Wu, Y-T; Hsu, H-Y; Tsai, M-C; Lin, M-J; Hsu, Y-C; Lin, C-H

2012-10-25

Minocycline is a second-generation tetracycline that has been reported to have powerful neuroprotective properties. In our previous studies, we found that d-amphetamine (AMPH) elicited action potential bursts in an identifiable RP4 neuron of the African snail, Achatina fulica Ferussac. This study sought to determine the effects of minocycline on the AMPH-elicited action potential pattern changes in the central snail neuron, using the two-electrode voltage clamping method. Extracellular application of AMPH at 300 μM elicited action potential bursts in the RP4 neuron. Minocycline dose-dependently (300-900 μM) inhibited the action potential bursts elicited by AMPH. The inhibitory effects of minocycline on AMPH-elicited action potential bursts were restored by forskolin (50 μM), an adenylate cyclase activator, and by dibutyryl cAMP (N(6),2'-O-Dibutyryladenosine 3',5'-cyclic monophosphate; 1mM), a membrane-permeable cAMP analog. Co-administration of forskolin (50 μM) plus tetraethylammonium chloride (TEA; 5mM) or co-administration of TEA (5mM) plus dibutyryl cAMP (1mM) also elicited action potential bursts, which were prevented and inhibited by minocycline. In addition, minocycline prevented and inhibited forskolin (100 μM)-elicited action potential bursts. Notably, TEA (50mM)-elicited action potential bursts in the RP4 neuron were not affected by minocycline. Minocycline did not affect steady-state outward currents of the RP4 neuron. However, minocycline did decrease the AMPH-elicited steady-state current changes. Similarly, minocycline decreased the effects of forskolin-elicited steady-state current changes. Pretreatment with H89 (N-[2-(p-Bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride; 10 μM), a protein kinase A inhibitor, inhibited AMPH-elicited action potential bursts and decreased AMPH-elicited steady-state current changes. These results suggest that the cAMP-protein kinase A signaling pathway and the steady-state current are involved in

Action-angle Maps and Scattering Theory for Some Finite-dimensional Integrable Systems III. Sutherland Type Systems and their Duals

NARCIS (Netherlands)

S.N.M. Ruijsenaars (Simon)

1995-01-01

textabstractWe present an explicit construction of an action-angle map for the nonrelativistic N-particle Sutherland system and for two different generalizations thereof, one of which may be viewed as a relativistic version. We use the map to obtain detailed information concerning dynamical issues

[Patterns of action potential firing in cortical neurons of neonatal mice and their electrophysiological property].

Science.gov (United States)

Furong, Liu; Shengtian, L I

2016-05-25

To investigate patterns of action potential firing in cortical heurons of neonatal mice and their electrophysiological properties. The passive and active membrane properties of cortical neurons from 3-d neonatal mice were observed by whole-cell patch clamp with different voltage and current mode. Three patterns of action potential firing were identified in response to depolarized current injection. The effects of action potential firing patterns on voltage-dependent inward and outward current were found. Neurons with three different firing patterns had different thresholds of depolarized current. In the morphology analysis of action potential, the three type neurons were different in rise time, duration, amplitude and threshold of the first action potential evoked by 80 pA current injection. The passive properties were similar in three patterns of action potential firing. These results indicate that newborn cortical neurons exhibit different patterns of action potential firing with different action potential parameters such as shape and threshold.

Triangulation of the monophasic action potential causes flattening of the electrocardiographic T-wave

DEFF Research Database (Denmark)

Bhuiyan, Tanveer Ahmed; Graff, Claus; Thomsen, Morten Bækgaard

2012-01-01

of the action potential under the effect of the IKr blocker sertindole and associated these changes to concurrent changes in the morphology of electrocardiographic T-waves in dogs. We show that, under the effect of sertindole, the peak changes in the morphology of action potentials occur at time points similar......It has been proposed that triangulation on the cardiac action potential manifests as a broadened, more flat and notched T-wave on the ECG but to what extent such morphology characteristics are indicative of triangulation is more unclear. In this paper, we have analyzed the morphological changes...... to those observed for the peak changes in T-wave morphology on the ECG. We further show that the association between action potential shape and ECG shape is dose-dependent and most prominent at the time corresponding to phase 3 of the action potential....

Prolonged action potential duration in cardiac ablation of PDK1 mice.

Science.gov (United States)

Han, Zhonglin; Jiang, Yu; Yang, Zhongzhou; Cao, Kejiang; Wang, Dao W

2015-01-01

The involvement of the AGC protein kinase family in regulating arrhythmia has drawn considerable attention, but the underlying mechanisms are still not clear. The aim of this study is to explore the role of 3-phosphoinositide-dependent protein kinase-1 (PDK1), one of upstream protein kinases of the AGC protein kinase family, in the pathogenesis of dysregulated electrophysiological basis. PDK1(F/F) αMHC-Cre mice and PDK1(F/F) mice were divided into experiment group and control group. Using patch clamping technology, we explored action potential duration in both groups, and investigated the functions of transient outward potassium channel and L-type Ca(2+) channel to explain the abnormal action potential duration. Significant prolongation action potential duration was found in mice with PDK1 deletion. Further, the peak current of transient outward potassium current and L-type Ca(2+) current were decreased by 84% and 49% respectively. In addition, dysregulation of channel kinetics lead to action potential duration prolongation further. In conclusion, we have demonstrated that PDK1 participates in action potential prolongation in cardiac ablation of PDK1 mice. This effect is likely to be mediated largely through downregulation of transient outward potassium current. These findings indicate the modulation of the PDK1 pathway could provide a new mechanism for abnormal electrophysiological basis.

Towards the Baum-Connes' analytical assembly map for the actions of discrete quantum groups

International Nuclear Information System (INIS)

Goswami, D.; Kuku, A.O.

2002-07-01

Given an action of a discrete quantum group (in the sense of Van Daele, Kustermans and Effros-Ruan) A on a C*-algebra C, satisfying some regularity assumptions resembling the proper Γ-compact action for a classical discrete group Γ on some space, we are able to construct canonical maps μ r i (μ i respectively) (i=0,1) from the A-equivariant K-homology groups KK i A (C,C) to the K-theory groups K i (A-circumflex r ) (K i (A-circumflex) respectively), where A-circumflex r and A-circumflex stand for the quantum analogues of the reduced and full group C*-algebras. We follow the steps of the construction of the classical Baum-Connes map, although in the context of quantum group the nontrivial modular property of the invariant weights (and the related fact that the square of the antipode is not identity) has to be taken into serious consideration, making it somewhat tricky to guess and prove the correct definitions of relevant Hilbert module structures. (author)

Fiber Optic Detection of Action Potentials in Axons

National Research Council Canada - National Science Library

Smela, Elisabeth

2006-01-01

In prior exploratory research, we had designed a fiber optic sensor utilizing a long period Bragg grating for the purpose of detecting action potentials in axons optically, through a change in index...

TRH regulates action potential shape in cerebral cortex pyramidal neurons.

Science.gov (United States)

Rodríguez-Molina, Víctor; Patiño, Javier; Vargas, Yamili; Sánchez-Jaramillo, Edith; Joseph-Bravo, Patricia; Charli, Jean-Louis

2014-07-07

Thyrotropin releasing hormone (TRH) is a neuropeptide with a wide neural distribution and a variety of functions. It modulates neuronal electrophysiological properties, including resting membrane potential, as well as excitatory postsynaptic potential and spike frequencies. We explored, with whole-cell patch clamp, TRH effect on action potential shape in pyramidal neurons of the sensorimotor cortex. TRH reduced spike and after hyperpolarization amplitudes, and increased spike half-width. The effect varied with dose, time and cortical layer. In layer V, 0.5µM of TRH induced a small increase in spike half-width, while 1 and 5µM induced a strong but transient change in spike half-width, and amplitude; after hyperpolarization amplitude was modified at 5µM of TRH. Cortical layers III and VI neurons responded intensely to 0.5µM TRH; layer II neurons response was small. The effect of 1µM TRH on action potential shape in layer V neurons was blocked by G-protein inhibition. Inhibition of the activity of the TRH-degrading enzyme pyroglutamyl peptidase II (PPII) reproduced the effect of TRH, with enhanced spike half-width. Many cortical PPII mRNA+ cells were VGLUT1 mRNA+, and some GAD mRNA+. These data show that TRH regulates action potential shape in pyramidal cortical neurons, and are consistent with the hypothesis that PPII controls its action in this region. Copyright © 2014 Elsevier B.V. All rights reserved.

Voltage-gated sodium channel expression and action potential generation in differentiated NG108-15 cells.

Science.gov (United States)

Liu, Jinxu; Tu, Huiyin; Zhang, Dongze; Zheng, Hong; Li, Yu-Long

2012-10-25

The generation of action potential is required for stimulus-evoked neurotransmitter release in most neurons. Although various voltage-gated ion channels are involved in action potential production, the initiation of the action potential is mainly mediated by voltage-gated Na+ channels. In the present study, differentiation-induced changes of mRNA and protein expression of Na+ channels, Na+ currents, and cell membrane excitability were investigated in NG108-15 cells. Whole-cell patch-clamp results showed that differentiation (9 days) didn't change cell membrane excitability, compared to undifferentiated state. But differentiation (21 days) induced the action potential generation in 45.5% of NG108-15 cells (25/55 cells). In 9-day-differentiated cells, Na+ currents were mildly increased, which was also found in 21-day differentiated cells without action potential. In 21-day differentiated cells with action potential, Na+ currents were significantly enhanced. Western blot data showed that the expression of Na+ channels was increased with differentiated-time dependent manner. Single-cell real-time PCR data demonstrated that the expression of Na+ channel mRNA was increased by 21 days of differentiation in NG108-15 cells. More importantly, the mRNA level of Na+ channels in cells with action potential was higher than that in cells without action potential. Differentiation induces expression of voltage-gated Na+ channels and action potential generation in NG108-15 cells. A high level of the Na+ channel density is required for differentiation-triggered action potential generation.

Membrane, action, and oscillatory potentials in simulated protocells

Science.gov (United States)

Syren, R. M.; Fox, S. W.; Przybylski, A. T.; Stratten, W. P.

1982-01-01

Electrical membrane potentials, oscillations, and action potentials are observed in proteinoid microspheres impaled with (3 M KCl) microelectrodes. Although effects are of greater magnitude when the vesicles contain glycerol and natural or synthetic lecithin, the results in the purely synthetic thermal protein structures are substantial, attaining 20 mV amplitude in some cases. The results add the property of electrical potential to the other known properties of proteinoid microspheres, in their role as models for protocells.

Introducing the Action Potential to Psychology Students

Science.gov (United States)

Simon-Dack, Stephanie L.

2014-01-01

For this simple active learning technique for teaching, students are assigned "roles" and act out the process of the action potential (AP), including the firing threshold, ion-specific channels for ions to enter and leave the cell, diffusion, and the refractory period. Pre-post test results indicated that students demonstrated increased…

Perturbation analysis of spontaneous action potential initiation by stochastic ion channels

KAUST Repository

Keener, James P.

2011-07-01

A stochastic interpretation of spontaneous action potential initiation is developed for the Morris-Lecar equations. Initiation of a spontaneous action potential can be interpreted as the escape from one of the wells of a double well potential, and we develop an asymptotic approximation of the mean exit time using a recently developed quasistationary perturbation method. Using the fact that the activating ionic channel\\'s random openings and closings are fast relative to other processes, we derive an accurate estimate for the mean time to fire an action potential (MFT), which is valid for a below-threshold applied current. Previous studies have found that for above-threshold applied current, where there is only a single stable fixed point, a diffusion approximation can be used. We also explore why different diffusion approximation techniques fail to estimate the MFT. © 2011 American Physical Society.

Action potentials in retinal ganglion cells are initiated at the site of maximal curvature of the extracellular potential.

Science.gov (United States)

Eickenscheidt, Max; Zeck, Günther

2014-06-01

The initiation of an action potential by extracellular stimulation occurs after local depolarization of the neuronal membrane above threshold. Although the technique shows remarkable clinical success, the site of action and the relevant stimulation parameters are not completely understood. Here we identify the site of action potential initiation in rabbit retinal ganglion cells (RGCs) interfaced to an array of extracellular capacitive stimulation electrodes. We determine which feature of the extracellular potential governs action potential initiation by simultaneous stimulation and recording RGCs interfaced in epiretinal configuration. Stimulation electrodes were combined to areas of different size and were presented at different positions with respect to the RGC. Based on stimulation by electrodes beneath the RGC soma and simultaneous sub-millisecond latency measurement we infer axonal initiation at the site of maximal curvature of the extracellular potential. Stimulation by electrodes at different positions along the axon reveals a nearly constant threshold current density except for a narrow region close to the cell soma. These findings are explained by the concept of the activating function modified to consider a region of lower excitability close to the cell soma. We present a framework how to estimate the site of action potential initiation and the stimulus required to cross threshold in neurons tightly interfaced to capacitive stimulation electrodes. Our results underscore the necessity of rigorous electrical characterization of the stimulation electrodes and of the interfaced neural tissue.

The inventorying and mapping of landslide potential in Manado – Indonesia

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Mithel Kumajas

2016-05-01

Full Text Available Landslide constitutes a frequent problem occurs in Manado. It happens for many times from year to year and brings both material disadvantage and casualty. The way and hilly topography of Manado, unstabel geological condition, high rainfall, and the improper land use are assumed to be the trigger for the problem. The objective of this study is to inventory and map landslide potential area as well as to design the preventive plan. Mapping method employs spatial approach by using land unit as the analysis unit. The technique of analysis applies the assistance of GIS with its ArcView soft ware. The result of mapping shows that the level landslide potential from potential until very potential category in Manado is 1.815,72 Ha; potential is 1282,10 ha and very potential category is 533,62 ha. The faktors cause the landslide comprise of rocky declivity, high rainfall, and the condition of stone as well as the unstabel and porous soil. The existence of Cesar zone extends to the center of the city and the use of settlement land located in improper zone become the trigger that quicken the occurrence of landslide. The strategy implemented to manage the landslide potential area can be carried out through 1 law enforcement in relation to city lay out, 2 landslide prevention through civil and vegetative technique, 3 the improvement of social consciousness of the danger of landslide disaster and the attempt for social empowerment, and 4 the provision of the landslide potential danger map as the ground for policy making in the effort to manage the landslide disaster.

Alteration of neural action potential patterns by axonal stimulation: the importance of stimulus location.

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Crago, Patrick E; Makowski, Nathaniel S

2014-10-01

Stimulation of peripheral nerves is often superimposed on ongoing motor and sensory activity in the same axons, without a quantitative model of the net action potential train at the axon endpoint. We develop a model of action potential patterns elicited by superimposing constant frequency axonal stimulation on the action potentials arriving from a physiologically activated neural source. The model includes interactions due to collision block, resetting of the neural impulse generator, and the refractory period of the axon at the point of stimulation. Both the mean endpoint firing rate and the probability distribution of the action potential firing periods depend strongly on the relative firing rates of the two sources and the intersite conduction time between them. When the stimulus rate exceeds the neural rate, neural action potentials do not reach the endpoint and the rate of endpoint action potentials is the same as the stimulus rate, regardless of the intersite conduction time. However, when the stimulus rate is less than the neural rate, and the intersite conduction time is short, the two rates partially sum. Increases in stimulus rate produce non-monotonic increases in endpoint rate and continuously increasing block of neurally generated action potentials. Rate summation is reduced and more neural action potentials are blocked as the intersite conduction time increases. At long intersite conduction times, the endpoint rate simplifies to being the maximum of either the neural or the stimulus rate. This study highlights the potential of increasing the endpoint action potential rate and preserving neural information transmission by low rate stimulation with short intersite conduction times. Intersite conduction times can be decreased with proximal stimulation sites for muscles and distal stimulation sites for sensory endings. The model provides a basis for optimizing experiments and designing neuroprosthetic interventions involving motor or sensory stimulation.

Determination of cable parameters in skeletal muscle fibres during repetitive firing of action potentials

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Riisager, Anders; Duehmke, Rudy; Nielsen, Ole Bækgaard; Huang, Christopher L; Pedersen, Thomas Holm

2014-01-01

Recent studies in rat muscle fibres show that repetitive firing of action potentials causes changes in fibre resting membrane conductance (Gm) that reflect regulation of ClC-1 Cl− and KATP K+ ion channels. Methodologically, these findings were obtained by inserting two microelectrodes at close proximity in the same fibres enabling measurements of fibre input resistance (Rin) in between action potential trains. Since the fibre length constant (λ) could not be determined, however, the calculation of Gm relied on the assumptions that the specific cytosolic resistivity (Ri) and muscle fibre volume remained constant during the repeated action potential firing. Here we present a three-microelectrode technique that enables determinations of multiple cable parameters in action potential-firing fibres including Rin and λ as well as waveform and conduction velocities of fully propagating action potentials. It is shown that in both rat and mouse extensor digitorum longus (EDL) fibres, action potential firing leads to substantial changes in both muscle fibre volume and Ri. The analysis also showed, however, that regardless of these changes, rat and mouse EDL fibres both exhibited initial decreases in Gm that were eventually followed by a ∼3-fold, fully reversible increase in Gm after the firing of 1450–1800 action potentials. Using this three-electrode method we further show that the latter rise in Gm was closely associated with excitation failures and loss of action potential signal above −20 mV. PMID:25128573

Revisiting the Therapeutic Potential of Bothrops jararaca Venom: Screening for Novel Activities Using Connectivity Mapping

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Carolina Alves Nicolau

2018-02-01

Full Text Available Snake venoms are sources of molecules with proven and potential therapeutic applications. However, most activities assayed in venoms (or their components are of hemorrhagic, hypotensive, edematogenic, neurotoxic or myotoxic natures. Thus, other relevant activities might remain unknown. Using functional genomics coupled to the connectivity map (C-map approach, we undertook a wide range indirect search for biological activities within the venom of the South American pit viper Bothrops jararaca. For that effect, venom was incubated with human breast adenocarcinoma cell line (MCF7 followed by RNA extraction and gene expression analysis. A list of 90 differentially expressed genes was submitted to biosimilar drug discovery based on pattern recognition. Among the 100 highest-ranked positively correlated drugs, only the antihypertensive, antimicrobial (both antibiotic and antiparasitic, and antitumor classes had been previously reported for B. jararaca venom. The majority of drug classes identified were related to (1 antimicrobial activity; (2 treatment of neuropsychiatric illnesses (Parkinson’s disease, schizophrenia, depression, and epilepsy; (3 treatment of cardiovascular diseases, and (4 anti-inflammatory action. The C-map results also indicated that B. jararaca venom may have components that target G-protein-coupled receptors (muscarinic, serotonergic, histaminergic, dopaminergic, GABA, and adrenergic and ion channels. Although validation experiments are still necessary, the C-map correlation to drugs with activities previously linked to snake venoms supports the efficacy of this strategy as a broad-spectrum approach for biological activity screening, and rekindles the snake venom-based search for new therapeutic agents.

Renewable energy: GIS-based mapping and modelling of potentials and demand

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Blaschke, Thomas; Biberacher, Markus; Schardinger, Ingrid.; Gadocha, Sabine; Zocher, Daniela

2010-05-01

Worldwide demand of energy is growing and will continue to do so for the next decades to come. IEA has estimated that global primary energy demand will increase by 40 - 50% from 2003 to 2030 (IEA, 2005) depending on the fact whether currently contemplated energy policies directed towards energy-saving and fuel-diversification will be effectuated. The demand for Renewable Energy (RE) is undenied but clear figures and spatially disaggregated potentials for the various energy carriers are very rare. Renewable Energies are expected to reduce pressures on the environment and CO2 production. In several studies in Germany (North-Rhine Westphalia and Lower Saxony) and Austria we studied the current and future pattern of energy production and consumption. In this paper we summarize and benchmark different RE carriers, namely wind, biomass (forest and non-forest, geothermal, solar and hydro power. We demonstrate that GIS-based scalable and flexible information delivery sheds new light on the prevailing metaphor of GIS as a processing engine serving needs of users more on demand rather than through ‘maps on stock'. We compare our finding with those of several energy related EU-FP7 projects in Europe where we have been involved - namely GEOBENE, REACCESS, ENERGEO - and demonstrate that more and more spatial data will become available together with tools that allow experts to do their own analyses and to communicate their results in ways which policy makers and the public can readily understand and use as a basis for their own actions. Geoportals in combination with standardised geoprocessing today supports the older vision of an automated presentation of data on maps, and - if user privileges are given - facilities to interactively manipulate these maps. We conclude that the most critical factor in modelling energy supply and demand remain the economic valuation of goods and services, especially the forecast of future end consumer energy costs.

Nanoelectronics-biology frontier: From nanoscopic probes for action potential recording in live cells to three-dimensional cyborg tissues.

Science.gov (United States)

Duan, Xiaojie; Fu, Tian-Ming; Liu, Jia; Lieber, Charles M

2013-08-01

for the first time using macroporous nanoelectronic scaffolds that are analogous to synthetic tissue scaffold and the extracellular matrix in tissue. Free-standing 3D nanoelectronic scaffolds were cultured with neurons, cardiomyocytes and smooth muscle cells to yield electronically-innervated synthetic or 'cyborg' tissues. Measurements demonstrate that innervated tissues exhibit similar cell viability as with conventional tissue scaffolds, and importantly, demonstrate that the real-time response to drugs and pH changes can be mapped in 3D through the tissues. These results open up a new field of research, wherein nanoelectronics are merged with biological systems in 3D thereby providing broad opportunities, ranging from a nanoelectronic/tissue platform for real-time pharmacological screening in 3D to implantable 'cyborg' tissues enabling closed-loop monitoring and treatment of diseases. Furthermore, the capability of high density scale-up of the above extra- and intracellular nanoscopic probes for action potential recording provide important tools for large-scale high spatio-temporal resolution electrical neural activity mapping in both 2D and 3D, which promises to have a profound impact on many research areas, including the mapping of activity within the brain.

Predictive mapping of the acidifying potential for acid sulfate soils

DEFF Research Database (Denmark)

Boman, A; Beucher, Amélie; Mattbäck, S

Developing methods for the predictive mapping of the potential environmental impact from acid sulfate soils is important because recent studies (e.g. Mattbäck et al., under revision) have shown that the environmental hazards (e.g. leaching of acidity) related to acid sulfate soils vary depending...... on their texture (clay, silt, sand etc.). Moreover, acidity correlates, not only with the sulfur content, but also with the electrical conductivity (EC) measured after incubation. Electromagnetic induction (EMI) data collected from an EM38 proximal sensor also enabled the detailed mapping of acid sulfate soils...... over a field (Huang et al., 2014).This study aims at assessing the use of EMI data for the predictive mapping of the acidifying potential in an acid sulfate soil area in western Finland. Different supervised classification modelling techniques, such as Artificial Neural Networks (Beucher et al., 2015...

Rosewood oil induces sedation and inhibits compound action potential in rodents.

Science.gov (United States)

de Almeida, Reinaldo Nóbrega; Araújo, Demétrius Antonio Machado; Gonçalves, Juan Carlos Ramos; Montenegro, Fabrícia Costa; de Sousa, Damião Pergentino; Leite, José Roberto; Mattei, Rita; Benedito, Marco Antonio Campana; de Carvalho, José Gilberto Barbosa; Cruz, Jader Santos; Maia, José Guilherme Soares

2009-07-30

Aniba rosaeodora is an aromatic plant which has been used in Brazil folk medicine due to its sedative effect. Therefore, the purpose of the present study was to evaluate the sedative effect of linalool-rich rosewood oil in mice. In addition we sought to investigate the linalool-rich oil effects on the isolated nerve using the single sucrose-gap technique. Sedative effect was determined by measuring the potentiation of the pentobarbital-induced sleeping time. The compound action potential amplitude was evaluated as a way to detect changes in excitability of the isolated nerve. The results showed that administration of rosewood oil at the doses of 200 and 300 mg/kg significantly decreased latency and increased the duration of sleeping time. On the other hand, the dose of 100 mg/kg potentiated significantly the pentobarbital action decreasing pentobarbital latency time and increasing pentobarbital sleeping time. In addition, the effect of linalool-rich rosewood oil on the isolated nerve of the rat was also investigated through the single sucrose-gap technique. The amplitude of the action potential decreased almost 100% when it was incubated for 30 min at 100 microg/ml. From this study, it is suggested a sedative effect of linalool-rich rosewood oil that could, at least in part, be explained by the reduction in action potential amplitude that provokes a decrease in neuronal excitability.

Improving Cardiac Action Potential Measurements: 2D and 3D Cell Culture.

Science.gov (United States)

Daily, Neil J; Yin, Yue; Kemanli, Pinar; Ip, Brian; Wakatsuki, Tetsuro

2015-11-01

Progress in the development of assays for measuring cardiac action potential is crucial for the discovery of drugs for treating cardiac disease and assessing cardiotoxicity. Recently, high-throughput methods for assessing action potential using induced pluripotent stem cell (iPSC) derived cardiomyocytes in both two-dimensional monolayer cultures and three-dimensional tissues have been developed. We describe an improved method for assessing cardiac action potential using an ultra-fast cost-effective plate reader with commercially available dyes. Our methods improve dramatically the detection of the fluorescence signal from these dyes and make way for the development of more high-throughput methods for cardiac drug discovery and cardiotoxicity.

Mapping geogenic radon potential by regression kriging

Energy Technology Data Exchange (ETDEWEB)

Pásztor, László [Institute for Soil Sciences and Agricultural Chemistry, Centre for Agricultural Research, Hungarian Academy of Sciences, Department of Environmental Informatics, Herman Ottó út 15, 1022 Budapest (Hungary); Szabó, Katalin Zsuzsanna, E-mail: sz_k_zs@yahoo.de [Department of Chemistry, Institute of Environmental Science, Szent István University, Páter Károly u. 1, Gödöllő 2100 (Hungary); Szatmári, Gábor; Laborczi, Annamária [Institute for Soil Sciences and Agricultural Chemistry, Centre for Agricultural Research, Hungarian Academy of Sciences, Department of Environmental Informatics, Herman Ottó út 15, 1022 Budapest (Hungary); Horváth, Ákos [Department of Atomic Physics, Eötvös University, Pázmány Péter sétány 1/A, 1117 Budapest (Hungary)

2016-02-15

Radon ({sup 222}Rn) gas is produced in the radioactive decay chain of uranium ({sup 238}U) which is an element that is naturally present in soils. Radon is transported mainly by diffusion and convection mechanisms through the soil depending mainly on the physical and meteorological parameters of the soil and can enter and accumulate in buildings. Health risks originating from indoor radon concentration can be attributed to natural factors and is characterized by geogenic radon potential (GRP). Identification of areas with high health risks require spatial modeling, that is, mapping of radon risk. In addition to geology and meteorology, physical soil properties play a significant role in the determination of GRP. In order to compile a reliable GRP map for a model area in Central-Hungary, spatial auxiliary information representing GRP forming environmental factors were taken into account to support the spatial inference of the locally measured GRP values. Since the number of measured sites was limited, efficient spatial prediction methodologies were searched for to construct a reliable map for a larger area. Regression kriging (RK) was applied for the interpolation using spatially exhaustive auxiliary data on soil, geology, topography, land use and climate. RK divides the spatial inference into two parts. Firstly, the deterministic component of the target variable is determined by a regression model. The residuals of the multiple linear regression analysis represent the spatially varying but dependent stochastic component, which are interpolated by kriging. The final map is the sum of the two component predictions. Overall accuracy of the map was tested by Leave-One-Out Cross-Validation. Furthermore the spatial reliability of the resultant map is also estimated by the calculation of the 90% prediction interval of the local prediction values. The applicability of the applied method as well as that of the map is discussed briefly. - Highlights: • A new method

Mapping geogenic radon potential by regression kriging

International Nuclear Information System (INIS)

Pásztor, László; Szabó, Katalin Zsuzsanna; Szatmári, Gábor; Laborczi, Annamária; Horváth, Ákos

2016-01-01

Radon ( 222 Rn) gas is produced in the radioactive decay chain of uranium ( 238 U) which is an element that is naturally present in soils. Radon is transported mainly by diffusion and convection mechanisms through the soil depending mainly on the physical and meteorological parameters of the soil and can enter and accumulate in buildings. Health risks originating from indoor radon concentration can be attributed to natural factors and is characterized by geogenic radon potential (GRP). Identification of areas with high health risks require spatial modeling, that is, mapping of radon risk. In addition to geology and meteorology, physical soil properties play a significant role in the determination of GRP. In order to compile a reliable GRP map for a model area in Central-Hungary, spatial auxiliary information representing GRP forming environmental factors were taken into account to support the spatial inference of the locally measured GRP values. Since the number of measured sites was limited, efficient spatial prediction methodologies were searched for to construct a reliable map for a larger area. Regression kriging (RK) was applied for the interpolation using spatially exhaustive auxiliary data on soil, geology, topography, land use and climate. RK divides the spatial inference into two parts. Firstly, the deterministic component of the target variable is determined by a regression model. The residuals of the multiple linear regression analysis represent the spatially varying but dependent stochastic component, which are interpolated by kriging. The final map is the sum of the two component predictions. Overall accuracy of the map was tested by Leave-One-Out Cross-Validation. Furthermore the spatial reliability of the resultant map is also estimated by the calculation of the 90% prediction interval of the local prediction values. The applicability of the applied method as well as that of the map is discussed briefly. - Highlights: • A new method, regression

Multiple modes of action potential initiation and propagation in mitral cell primary dendrite

DEFF Research Database (Denmark)

Chen, Wei R; Shen, Gongyu Y; Shepherd, Gordon M

2002-01-01

recordings with computational modeling to analyze action-potential initiation and propagation in the primary dendrite. In response to depolarizing current injection or distal olfactory nerve input, fast Na(+) action potentials were recorded along the entire length of the primary dendritic trunk. With weak......-to-moderate olfactory nerve input, an action potential was initiated near the soma and then back-propagated into the primary dendrite. As olfactory nerve input increased, the initiation site suddenly shifted to the distal primary dendrite. Multi-compartmental modeling indicated that this abrupt shift of the spike......-initiation site reflected an independent thresholding mechanism in the distal dendrite. When strong olfactory nerve excitation was paired with strong inhibition to the mitral cell basal secondary dendrites, a small fast prepotential was recorded at the soma, which indicated that an action potential was initiated...

Ionic channels underlying the ventricular action potential in zebrafish embryo.

Science.gov (United States)

Alday, Aintzane; Alonso, Hiart; Gallego, Monica; Urrutia, Janire; Letamendia, Ainhoa; Callol, Carles; Casis, Oscar

2014-06-01

Over the last years zebrafish has become a popular model in the study of cardiac physiology, pathology and pharmacology. Recently, the application of the 3Rs regulation and the characteristics of the embryo have reduced the use of adult zebrafish use in many studies. However, the zebrafish embryo cardiac physiology is poorly characterized since most works have used indirect techniques and direct recordings of cardiac action potential and ionic currents are scarce. In order to optimize the zebrafish embryo model, we used electrophysiological, pharmacological and immunofluorescence tools to identify the characteristics and the ionic channels involved in the ventricular action potentials of zebrafish embryos. The application of Na(+) or T-type Ca(+2) channel blockers eliminated the cardiac electrical activity, indicating that the action potential upstroke depends on Na(+) and T-type Ca(+2) currents. The plateau phase depends on L-type Ca(+2) channels since it is abolished by specific blockade. The direct channel blockade indicates that the action potential repolarization and diastolic potential depends on ERG K(+) channels. The presence in the embryonic heart of the Nav1.5, Cav1.2, Cav3.2 and ERG channels was also confirmed by immunofluorescence, while the absence of effect of specific blockers and immunostaining indicate that two K(+) repolarizing currents present in human heart, Ito and IKs, are absent in the embryonic zebrafish heart. Our results describe the ionic channels present and its role in the zebrafish embryo heart and support the use of zebrafish embryos to study human diseases and their use for drug testing. Copyright © 2014 Elsevier Ltd. All rights reserved.

Decoupling Action Potential Bias from Cortical Local Field Potentials

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Stephen V. David

2010-01-01

Full Text Available Neurophysiologists have recently become interested in studying neuronal population activity through local field potential (LFP recordings during experiments that also record the activity of single neurons. This experimental approach differs from early LFP studies because it uses high impendence electrodes that can also isolate single neuron activity. A possible complication for such studies is that the synaptic potentials and action potentials of the small subset of isolated neurons may contribute disproportionately to the LFP signal, biasing activity in the larger nearby neuronal population to appear synchronous and cotuned with these neurons. To address this problem, we used linear filtering techniques to remove features correlated with spike events from LFP recordings. This filtering procedure can be applied for well-isolated single units or multiunit activity. We illustrate the effects of this correction in simulation and on spike data recorded from primary auditory cortex. We find that local spiking activity can explain a significant portion of LFP power at most recording sites and demonstrate that removing the spike-correlated component can affect measurements of auditory tuning of the LFP.

Warm Body Temperature Facilitates Energy Efficient Cortical Action Potentials

Science.gov (United States)

Yu, Yuguo; Hill, Adam P.; McCormick, David A.

2012-01-01

The energy efficiency of neural signal transmission is important not only as a limiting factor in brain architecture, but it also influences the interpretation of functional brain imaging signals. Action potential generation in mammalian, versus invertebrate, axons is remarkably energy efficient. Here we demonstrate that this increase in energy efficiency is due largely to a warmer body temperature. Increases in temperature result in an exponential increase in energy efficiency for single action potentials by increasing the rate of Na+ channel inactivation, resulting in a marked reduction in overlap of the inward Na+, and outward K+, currents and a shortening of action potential duration. This increase in single spike efficiency is, however, counterbalanced by a temperature-dependent decrease in the amplitude and duration of the spike afterhyperpolarization, resulting in a nonlinear increase in the spike firing rate, particularly at temperatures above approximately 35°C. Interestingly, the total energy cost, as measured by the multiplication of total Na+ entry per spike and average firing rate in response to a constant input, reaches a global minimum between 37–42°C. Our results indicate that increases in temperature result in an unexpected increase in energy efficiency, especially near normal body temperature, thus allowing the brain to utilize an energy efficient neural code. PMID:22511855

Warm body temperature facilitates energy efficient cortical action potentials.

Directory of Open Access Journals (Sweden)

Yuguo Yu

Full Text Available The energy efficiency of neural signal transmission is important not only as a limiting factor in brain architecture, but it also influences the interpretation of functional brain imaging signals. Action potential generation in mammalian, versus invertebrate, axons is remarkably energy efficient. Here we demonstrate that this increase in energy efficiency is due largely to a warmer body temperature. Increases in temperature result in an exponential increase in energy efficiency for single action potentials by increasing the rate of Na(+ channel inactivation, resulting in a marked reduction in overlap of the inward Na(+, and outward K(+, currents and a shortening of action potential duration. This increase in single spike efficiency is, however, counterbalanced by a temperature-dependent decrease in the amplitude and duration of the spike afterhyperpolarization, resulting in a nonlinear increase in the spike firing rate, particularly at temperatures above approximately 35°C. Interestingly, the total energy cost, as measured by the multiplication of total Na(+ entry per spike and average firing rate in response to a constant input, reaches a global minimum between 37-42°C. Our results indicate that increases in temperature result in an unexpected increase in energy efficiency, especially near normal body temperature, thus allowing the brain to utilize an energy efficient neural code.

Sensory nerve action potentials and sensory perception in women with arthritis of the hand.

Science.gov (United States)

Calder, Kristina M; Martin, Alison; Lydiate, Jessica; MacDermid, Joy C; Galea, Victoria; MacIntyre, Norma J

2012-05-10

Arthritis of the hand can limit a person's ability to perform daily activities. Whether or not sensory deficits contribute to the disability in this population remains unknown. The primary purpose of this study was to determine if women with osteoarthritis (OA) or rheumatoid arthritis (RA) of the hand have sensory impairments. Sensory function in the dominant hand of women with hand OA or RA and healthy women was evaluated by measuring sensory nerve action potentials (SNAPs) from the median, ulnar and radial nerves, sensory mapping (SM), and vibratory and current perception thresholds (VPT and CPT, respectively) of the second and fifth digits. All SNAP amplitudes were significantly lower for the hand OA and hand RA groups compared with the healthy group (p sensory fibers in the median, ulnar and radial nerves. Less apparent were losses in conduction speed or sensory perception.

Direct detection of a single evoked action potential with MRS in Lumbricus terrestris.

Science.gov (United States)

Poplawsky, Alexander J; Dingledine, Raymond; Hu, Xiaoping P

2012-01-01

Functional MRI (fMRI) measures neural activity indirectly by detecting the signal change associated with the hemodynamic response following brain activation. In order to alleviate the temporal and spatial specificity problems associated with fMRI, a number of attempts have been made to detect neural magnetic fields (NMFs) with MRI directly, but have thus far provided conflicting results. In this study, we used MR to detect axonal NMFs in the median giant fiber of the earthworm, Lumbricus terrestris, by examining the free induction decay (FID) with a sampling interval of 0.32 ms. The earthworm nerve cords were isolated from the vasculature and stimulated at the threshold of action potential generation. FIDs were acquired shortly after the stimulation, and simultaneous field potential recordings identified the presence or absence of single evoked action potentials. FIDs acquired when the stimulus did not evoke an action potential were summed as background. The phase of the background-subtracted FID exhibited a systematic change, with a peak phase difference of (-1.2 ± 0.3) × 10(-5) radians occurring at a time corresponding to the timing of the action potential. In addition, we calculated the possible changes in the FID magnitude and phase caused by a simulated action potential using a volume conductor model. The measured phase difference matched the theoretical prediction well in both amplitude and temporal characteristics. This study provides the first evidence for the direct detection of a magnetic field from an evoked action potential using MR. Copyright © 2011 John Wiley & Sons, Ltd.

A fast Na+/Ca2+-based action potential in a marine diatom.

Directory of Open Access Journals (Sweden)

Alison R Taylor

Full Text Available BACKGROUND: Electrical impulses in animals play essential roles in co-ordinating an array of physiological functions including movement, secretion, environmental sensing and development. Underpinning many of these electrical signals is a fast Na+-based action potential that has been fully characterised only in cells associated with the neuromuscular systems of multicellular animals. Such rapid action potentials are thought to have evolved with the first metazoans, with cnidarians being the earliest representatives. The present study demonstrates that a unicellular protist, the marine diatom Odontella sinensis, can also generate a fast Na+/Ca2+ based action potential that has remarkably similar biophysical and pharmacological properties to invertebrates and vertebrate cardiac and skeletal muscle cells. METHODOLOGY/PRINCIPAL FINDINGS: The kinetic, ionic and pharmacological properties of the rapid diatom action potential were examined using single electrode current and voltage clamp techniques. Overall, the characteristics of the fast diatom currents most closely resemble those of vertebrate and invertebrate muscle Na+/Ca2+ currents. CONCLUSIONS/SIGNIFICANCE: This is the first demonstration of voltage-activated Na+ channels and the capacity to generate fast Na+-based action potentials in a unicellular photosynthetic organism. The biophysical and pharmacological characteristics together with the presence of a voltage activated Na+/Ca2+ channel homologue in the recently sequenced genome of the diatom Thalassiosira pseudonana, provides direct evidence supporting the hypothesis that this rapid signalling mechanism arose in ancestral unicellular eukaryotes and has been retained in at least two phylogenetically distant lineages of eukaryotes; opisthokonts and the stramenopiles. The functional role of the fast animal-like action potential in diatoms remains to be elucidated but is likely involved in rapid environmental sensing of these widespread and

Channel sialic acids limit hERG channel activity during the ventricular action potential.

Science.gov (United States)

Norring, Sarah A; Ednie, Andrew R; Schwetz, Tara A; Du, Dongping; Yang, Hui; Bennett, Eric S

2013-02-01

Activity of human ether-a-go-go-related gene (hERG) 1 voltage-gated K(+) channels is responsible for portions of phase 2 and phase 3 repolarization of the human ventricular action potential. Here, we questioned whether and how physiologically and pathophysiologically relevant changes in surface N-glycosylation modified hERG channel function. Voltage-dependent hERG channel gating and activity were evaluated as expressed in a set of Chinese hamster ovary (CHO) cell lines under conditions of full glycosylation, no sialylation, no complex N-glycans, and following enzymatic deglycosylation of surface N-glycans. For each condition of reduced glycosylation, hERG channel steady-state activation and inactivation relationships were shifted linearly by significant depolarizing ∼9 and ∼18 mV, respectively. The hERG window current increased significantly by 50-150%, and the peak shifted by a depolarizing ∼10 mV. There was no significant change in maximum hERG current density. Deglycosylated channels were significantly more active (20-80%) than glycosylated controls during phases 2 and 3 of action potential clamp protocols. Simulations of hERG current and ventricular action potentials corroborated experimental data and predicted reduced sialylation leads to a 50-70-ms decrease in action potential duration. The data describe a novel mechanism by which hERG channel gating is modulated through physiologically and pathophysiologically relevant changes in N-glycosylation; reduced channel sialylation increases hERG channel activity during the action potential, thereby increasing the rate of action potential repolarization.

A Parametric Computational Model of the Action Potential of Pacemaker Cells.

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Ai, Weiwei; Patel, Nitish D; Roop, Partha S; Malik, Avinash; Andalam, Sidharta; Yip, Eugene; Allen, Nathan; Trew, Mark L

2018-01-01

A flexible, efficient, and verifiable pacemaker cell model is essential to the design of real-time virtual hearts that can be used for closed-loop validation of cardiac devices. A new parametric model of pacemaker action potential is developed to address this need. The action potential phases are modeled using hybrid automaton with one piecewise-linear continuous variable. The model can capture rate-dependent dynamics, such as action potential duration restitution, conduction velocity restitution, and overdrive suppression by incorporating nonlinear update functions. Simulated dynamics of the model compared well with previous models and clinical data. The results show that the parametric model can reproduce the electrophysiological dynamics of a variety of pacemaker cells, such as sinoatrial node, atrioventricular node, and the His-Purkinje system, under varying cardiac conditions. This is an important contribution toward closed-loop validation of cardiac devices using real-time heart models.

Solar resources and power potential mapping in Vietnam using satellite-derived and GIS-based information

International Nuclear Information System (INIS)

Polo, J.; Bernardos, A.; Navarro, A.A.; Fernandez-Peruchena, C.M.; Ramírez, L.; Guisado, María V.; Martínez, S.

2015-01-01

Highlights: • Satellite-based, reanalysis data and measurements are combined for solar mapping. • Plant output modeling for PV and CSP results in simple expressions of solar potential. • Solar resource, solar potential are used in a GIS for determine technical solar potential. • Solar resource and potential maps of Vietnam are presented. - Abstract: The present paper presents maps of the solar resources in Vietnam and of the solar potential for concentrating solar power (CSP) and for grid-connected photovoltaic (PV) technology. The mapping of solar radiation components has been calculated from satellite-derived data combined with solar radiation derived from sunshine duration and other additional sources of information based on reanalysis for several atmospheric and meteorological parameters involved. Two scenarios have been selected for the study of the solar potential: CSP Parabolic Trough of 50 MWe and grid-connected Flat Plate PV plant of around 1 MWe. For each selected scenario plant performance simulations have been computed for developing simple expressions that allow the estimation of the solar potential from the annual solar irradiation and the latitude of every site in Vietnam. Finally, Geographic Information Systems (GIS) have been used for combining the solar potential with the land availability according each scenario to deliver the technical solar potential maps of Vietnam

Electrocorticographic Temporal Alteration Mapping: A Clinical Technique for Mapping the Motor Cortex with Movement-Related Cortical Potentials

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Zehan Wu

2017-06-01

Full Text Available We propose electrocorticographic temporal alteration mapping (ETAM for motor cortex mapping by utilizing movement-related cortical potentials (MRCPs within the low-frequency band [0.05-3] Hz. This MRCP waveform-based temporal domain approach was compared with the state-of-the-art electrocorticographic frequency alteration mapping (EFAM, which is based on frequency spectrum dynamics. Five patients (two epilepsy cases and three tumor cases were enrolled in the study. Each patient underwent intraoperative direct electrocortical stimulation (DECS procedure for motor cortex localization. Moreover, the patients were required to perform simple brisk wrist extension task during awake craniotomy surgery. Cross-validation results showed that the proposed ETAM method had high sensitivity (81.8% and specificity (94.3% in identifying sites which exhibited positive DECS motor responses. Moreover, although the sensitivity of the ETAM and EFAM approaches was not significantly different, ETAM had greater specificity compared with EFAM (94.3 vs. 86.1%. These results indicate that for the intraoperative functional brain mapping, ETAM is a promising novel approach for motor cortex localization with the potential to reduce the need for cortical electrical stimulation.

Cell-type-dependent action potentials and voltage-gated currents in mouse fungiform taste buds.

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Kimura, Kenji; Ohtubo, Yoshitaka; Tateno, Katsumi; Takeuchi, Keita; Kumazawa, Takashi; Yoshii, Kiyonori

2014-01-01

Taste receptor cells fire action potentials in response to taste substances to trigger non-exocytotic neurotransmitter release in type II cells and exocytotic release in type III cells. We investigated possible differences between these action potentials fired by mouse taste receptor cells using in situ whole-cell recordings, and subsequently we identified their cell types immunologically with cell-type markers, an IP3 receptor (IP3 R3) for type II cells and a SNARE protein (SNAP-25) for type III cells. Cells not immunoreactive to these antibodies were examined as non-IRCs. Here, we show that type II cells and type III cells fire action potentials using different ionic mechanisms, and that non-IRCs also fire action potentials with either of the ionic mechanisms. The width of action potentials was significantly narrower and their afterhyperpolarization was deeper in type III cells than in type II cells. Na(+) current density was similar in type II cells and type III cells, but it was significantly smaller in non-IRCs than in the others. Although outwardly rectifying current density was similar between type II cells and type III cells, tetraethylammonium (TEA) preferentially suppressed the density in type III cells and the majority of non-IRCs. Our mathematical model revealed that the shape of action potentials depended on the ratio of TEA-sensitive current density and TEA-insensitive current one. The action potentials of type II cells and type III cells under physiological conditions are discussed. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Imaging Action Potential in Single Mammalian Neurons by Tracking the Accompanying Sub-Nanometer Mechanical Motion.

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Yang, Yunze; Liu, Xian-Wei; Wang, Hui; Yu, Hui; Guan, Yan; Wang, Shaopeng; Tao, Nongjian

2018-03-28

Action potentials in neurons have been studied traditionally by intracellular electrophysiological recordings and more recently by the fluorescence detection methods. Here we describe a label-free optical imaging method that can measure mechanical motion in single cells with a sub-nanometer detection limit. Using the method, we have observed sub-nanometer mechanical motion accompanying the action potential in single mammalian neurons by averaging the repeated action potential spikes. The shape and width of the transient displacement are similar to those of the electrically recorded action potential, but the amplitude varies from neuron to neuron, and from one region of a neuron to another, ranging from 0.2-0.4 nm. The work indicates that action potentials may be studied noninvasively in single mammalian neurons by label-free imaging of the accompanying sub-nanometer mechanical motion.

Noise Enhances Action Potential Generation in Mouse Sensory Neurons via Stochastic Resonance.

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Onorato, Irene; D'Alessandro, Giuseppina; Di Castro, Maria Amalia; Renzi, Massimiliano; Dobrowolny, Gabriella; Musarò, Antonio; Salvetti, Marco; Limatola, Cristina; Crisanti, Andrea; Grassi, Francesca

2016-01-01

Noise can enhance perception of tactile and proprioceptive stimuli by stochastic resonance processes. However, the mechanisms underlying this general phenomenon remain to be characterized. Here we studied how externally applied noise influences action potential firing in mouse primary sensory neurons of dorsal root ganglia, modelling a basic process in sensory perception. Since noisy mechanical stimuli may cause stochastic fluctuations in receptor potential, we examined the effects of sub-threshold depolarizing current steps with superimposed random fluctuations. We performed whole cell patch clamp recordings in cultured neurons of mouse dorsal root ganglia. Noise was added either before and during the step, or during the depolarizing step only, to focus onto the specific effects of external noise on action potential generation. In both cases, step + noise stimuli triggered significantly more action potentials than steps alone. The normalized power norm had a clear peak at intermediate noise levels, demonstrating that the phenomenon is driven by stochastic resonance. Spikes evoked in step + noise trials occur earlier and show faster rise time as compared to the occasional ones elicited by steps alone. These data suggest that external noise enhances, via stochastic resonance, the recruitment of transient voltage-gated Na channels, responsible for action potential firing in response to rapid step-wise depolarizing currents.

Cortical Interneuron Subtypes Vary in Their Axonal Action Potential Properties.

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Casale, Amanda E; Foust, Amanda J; Bal, Thierry; McCormick, David A

2015-11-25

The role of interneurons in cortical microcircuits is strongly influenced by their passive and active electrical properties. Although different types of interneurons exhibit unique electrophysiological properties recorded at the soma, it is not yet clear whether these differences are also manifested in other neuronal compartments. To address this question, we have used voltage-sensitive dye to image the propagation of action potentials into the fine collaterals of axons and dendrites in two of the largest cortical interneuron subtypes in the mouse: fast-spiking interneurons, which are typically basket or chandelier neurons; and somatostatin containing interneurons, which are typically regular spiking Martinotti cells. We found that fast-spiking and somatostatin-expressing interneurons differed in their electrophysiological characteristics along their entire dendrosomatoaxonal extent. The action potentials generated in the somata and axons, including axon collaterals, of somatostatin-expressing interneurons are significantly broader than those generated in the same compartments of fast-spiking inhibitory interneurons. In addition, action potentials back-propagated into the dendrites of somatostatin-expressing interneurons much more readily than fast-spiking interneurons. Pharmacological investigations suggested that axonal action potential repolarization in both cell types depends critically upon Kv1 channels, whereas the axonal and somatic action potentials of somatostatin-expressing interneurons also depend on BK Ca(2+)-activated K(+) channels. These results indicate that the two broad classes of interneurons studied here have expressly different subcellular physiological properties, allowing them to perform unique computational roles in cortical circuit operations. Neurons in the cerebral cortex are of two major types: excitatory and inhibitory. The proper balance of excitation and inhibition in the brain is critical for its operation. Neurons contain three main

Re-modeling Chara action potential: II. The action potential form under salinity stress

Directory of Open Access Journals (Sweden)

Mary Jane Beilby

2017-04-01

Full Text Available In part I we established Thiel-Beilby model of the Chara action potential (AP. In part II the AP is investigated in detail at the time of saline stress. Even very short exposure of salt-sensitive Chara cells to artificial pond water with 50 mM NaCl (Saline APW modified the AP threshold and drastically altered the AP form. Detailed modeling of 14 saline APs from 3 cells established that both the Ca2+ pump and the Ca2+ channels on internal stores seem to be affected, with the changes sometimes cancelling and sometimes re-enforcing each other, leading to APs with long durations and very complex forms. The exposure to salinity offers further insights into AP mechanism and suggests future experiments. The prolonged APs lead to greater loss of chloride and potassium ions, compounding the effects of saline stress.

Hybrid geomorphological maps as the basis for assessing geoconservation potential in Lech, Vorarlberg (Austria)

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Seijmonsbergen, Harry; de Jong, Mat; Anders, Niels; de Graaff, Leo; Cammeraat, Erik

2013-04-01

Geoconservation potential is, in our approach, closely linked to the spatial distribution of geomorphological sites and thus, geomorphological inventories. Detailed geomorphological maps are translated, using a standardized workflow, into polygonal maps showing the potential geoconservation value of landforms. A new development is to semi-automatically extract in a GIS geomorphological information from high resolution topographical data, such as LiDAR, and combine this with conventional data types (e.g. airphotos, geological maps) into geomorphological maps. Such hybrid digital geomorphological maps are also easily translated into digital information layers which show the geoconservation potential in an area. We present a protocol for digital geomorphological mapping illustrated with an example for the municipality of Lech in Vorarlberg (Austria). The protocol consists of 5 steps: 1. data preparation, 2. generating training and validation samples, 3. parameterization, 4. feature extraction, and 5. assessing classification accuracy. The resulting semi-automated digital geomorphological map is then further validated, in two ways. Firstly, the map is manually checked with the help of a series of digital datasets (e.g. airphotos) in a digital 3D environment, such as ArcScene. The second validation is field visit, which preferably occurs in parallel to the digital evaluation, so that updates are quickly achieved. The final digital and coded geomorphological information layer is converted into a potential geoconservation map by weighting and ranking the landforms based on four criteria: scientific relevance, frequency of occurrence, disturbance, and environmental vulnerability. The criteria with predefined scores for the various landform types are stored in a separate GIS attribute table, which is joined to the attribute table of the hybrid geomorphological information layer in an automated procedure. The results of the assessment can be displayed as the potential

Action potential bursts in central snail neurons elicited by paeonol: roles of ionic currents

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Chen, Yi-hung; Lin, Pei-lin; Hsu, Hui-yu; Wu, Ya-ting; Yang, Han-yin; Lu, Dah-yuu; Huang, Shiang-suo; Hsieh, Ching-liang; Lin, Jaung-geng

2010-01-01

Aim: To investigate the effects of 2′-hydroxy-4′-methoxyacetophenone (paeonol) on the electrophysiological behavior of a central neuron (right parietal 4; RP4) of the giant African snail (Achatina fulica Ferussac). Methods: Intracellular recordings and the two-electrode voltage clamp method were used to study the effects of paeonol on the RP4 neuron. Results: The RP4 neuron generated spontaneous action potentials. Bath application of paeonol at a concentration of ≥500 μmol/L reversibly elicited action potential bursts in a concentration-dependent manner. Immersing the neurons in Co2+-substituted Ca2+-free solution did not block paeonol-elicited bursting. Pretreatment with the protein kinase A (PKA) inhibitor KT-5720 or the protein kinase C (PKC) inhibitor Ro 31-8220 did not affect the action potential bursts. Voltage-clamp studies revealed that paeonol at a concentration of 500 μmol/L had no remarkable effects on the total inward currents, whereas paeonol decreased the delayed rectifying K+ current (IKD) and the fast-inactivating K+ current (IA). Application of 4-aminopyridine (4-AP 5 mmol/L), an inhibitor of IA, or charybdotoxin 250 nmol/L, an inhibitor of the Ca2+-activated K+ current (IK(Ca)), failed to elicit action potential bursts, whereas tetraethylammonium chloride (TEA 50 mmol/L), an IKD blocker, successfully elicited action potential bursts. At a lower concentration of 5 mmol/L, TEA facilitated the induction of action potential bursts elicited by paeonol. Conclusion: Paeonol elicited a bursting firing pattern of action potentials in the RP4 neuron and this activity relates closely to the inhibitory effects of paeonol on the IKD. PMID:21042287

Selective activation of heteromeric SK channels contributes to action potential repolarization in mouse atrial myocytes.

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Hancock, Jane M; Weatherall, Kate L; Choisy, Stéphanie C; James, Andrew F; Hancox, Jules C; Marrion, Neil V

2015-05-01

Activation of small conductance calcium-activated potassium (SK) channels is proposed to contribute to repolarization of the action potential in atrial myocytes. This role is controversial, as these cardiac SK channels appear to exhibit an uncharacteristic pharmacology. The objectives of this study were to resolve whether activation of SK channels contributes to atrial action potential repolarization and to determine the likely subunit composition of the channel. The effect of 2 SK channel inhibitors was assessed on outward current evoked in voltage clamp and on action potential duration in perforated patch and whole-cell current clamp recording from acutely isolated mouse atrial myocytes. The presence of SK channel subunits was assessed using immunocytochemistry. A significant component of outward current was reduced by the SK channel blockers apamin and UCL1684. Block by apamin displayed a sensitivity indicating that this current was carried by homomeric SK2 channels. Action potential duration was significantly prolonged by UCL1684, but not by apamin. This effect was accompanied by an increase in beat-to-beat variability and action potential triangulation. This pharmacology was matched by that of expressed heteromeric SK2-SK3 channels in HEK293 cells. Immunocytochemistry showed that atrial myocytes express both SK2 and SK3 channels with an overlapping expression pattern. Only proposed heteromeric SK2-SK3 channels are physiologically activated to contribute to action potential repolarization, which is indicated by the difference in pharmacology of evoked outward current and prolongation of atrial action potential duration. The effect of blocking this channel on the action potential suggests that SK channel inhibition during cardiac function has the potential to be proarrhythmic. Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Modelling in vivo action potential propagation along a giant axon.

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George, Stuart; Foster, Jamie M; Richardson, Giles

2015-01-01

A partial differential equation model for the three-dimensional current flow in an excitable, unmyelinated axon is considered. Where the axon radius is significantly below a critical value R(crit) (that depends upon intra- and extra-cellular conductivity and ion channel conductance) the resistance of the intracellular space is significantly higher than that of the extracellular space, such that the potential outside the axon is uniformly small whilst the intracellular potential is approximated by the transmembrane potential. In turn, since the current flow is predominantly axial, it can be shown that the transmembrane potential is approximated by a solution to the one-dimensional cable equation. It is noted that the radius of the squid giant axon, investigated by (Hodgkin and Huxley 1952e), lies close to R(crit). This motivates us to apply the three-dimensional model to the squid giant axon and compare the results thus found to those obtained using the cable equation. In the context of the in vitro experiments conducted in (Hodgkin and Huxley 1952e) we find only a small difference between the wave profiles determined using these two different approaches and little difference between the speeds of action potential propagation predicted. This suggests that the cable equation approximation is accurate in this scenario. However when applied to the it in vivo setting, in which the conductivity of the surrounding tissue is considerably lower than that of the axoplasm, there are marked differences in both wave profile and speed of action potential propagation calculated using the two approaches. In particular, the cable equation significantly over predicts the increase in the velocity of propagation as axon radius increases. The consequences of these results are discussed in terms of the evolutionary costs associated with increasing the speed of action potential propagation by increasing axon radius.

7 CFR 1945.19 - Reporting potential natural disasters and initial actions.

Science.gov (United States)

2010-01-01

... 7 Agriculture 13 2010-01-01 2009-01-01 true Reporting potential natural disasters and initial... Assistance-General § 1945.19 Reporting potential natural disasters and initial actions. (a) Purpose. The purpose of reporting potential natural disasters is to provide a systematic procedure for rapid reporting...

Understanding the Electrical Behavior of the Action Potential in Terms of Elementary Electrical Sources

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Rodriguez-Falces, Javier

2015-01-01

A concept of major importance in human electrophysiology studies is the process by which activation of an excitable cell results in a rapid rise and fall of the electrical membrane potential, the so-called action potential. Hodgkin and Huxley proposed a model to explain the ionic mechanisms underlying the formation of action potentials. However,…

Action potential-independent and pharmacologically unique vesicular serotonin release from dendrites

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Colgan, Lesley A.; Cavolo, Samantha L.; Commons, Kathryn G.; Levitan, Edwin S.

2012-01-01

Serotonin released within the dorsal raphe nucleus (DR) induces feedback inhibition of serotonin neuron activity and consequently regulates mood-controlling serotonin release throughout the forebrain. Serotonin packaged in vesicles is released in response to action potentials by the serotonin neuron soma and terminals, but the potential for release by dendrites is unknown. Here three-photon (3P) microscopy imaging of endogenous serotonin in living rat brain slice, immunofluorescence and immuno-gold electron microscopy detection of VMAT2 (vesicular monoamine transporter 2) establish the presence of vesicular serotonin within DR dendrites. Furthermore, activation of glutamate receptors is shown to induce vesicular serotonin release from dendrites. However, unlike release from the soma and terminals, dendritic serotonin release is independent of action potentials, relies on L-type Ca2+ channels, is induced preferentially by NMDA, and displays distinct sensitivity to the selective serotonin reuptake inhibitor (SSRI) antidepressant fluoxetine. The unique control of dendritic serotonin release has important implications for DR physiology and the antidepressant action of SSRIs, dihydropyridines and NMDA receptor antagonists. PMID:23136413

Effects of tacrolimus on action potential configuration and transmembrane ion currents in canine ventricular cells.

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Szabó, László; Szentandrássy, Norbert; Kistamás, Kornél; Hegyi, Bence; Ruzsnavszky, Ferenc; Váczi, Krisztina; Horváth, Balázs; Magyar, János; Bányász, Tamás; Pál, Balázs; Nánási, Péter P

2013-03-01

Tacrolimus is a commonly used immunosuppressive agent which causes cardiovascular complications, e.g., hypertension and hypertrophic cardiomyopathy. In spite of it, there is little information on the cellular cardiac effects of the immunosuppressive agent tacrolimus in larger mammals. In the present study, therefore, the concentration-dependent effects of tacrolimus on action potential morphology and the underlying ion currents were studied in canine ventricular cardiomyocytes. Standard microelectrode, conventional whole cell patch clamp, and action potential voltage clamp techniques were applied in myocytes enzymatically dispersed from canine ventricular myocardium. Tacrolimus (3-30 μM) caused a concentration-dependent reduction of maximum velocity of depolarization and repolarization, action potential amplitude, phase-1 repolarization, action potential duration, and plateau potential, while no significant change in the resting membrane potential was observed. Conventional voltage clamp experiments revealed that tacrolimus concentrations ≥3 μM blocked a variety of ion currents, including I(Ca), I(to), I(K1), I(Kr), and I(Ks). Similar results were obtained under action potential voltage clamp conditions. These effects of tacrolimus developed rapidly and were fully reversible upon washout. The blockade of inward currents with the concomitant shortening of action potential duration in canine myocytes is the opposite of those observed previously with tacrolimus in small rodents. It is concluded that although tacrolimus blocks several ion channels at higher concentrations, there is no risk of direct interaction with cardiac ion channels when applying tacrolimus in therapeutic concentrations.

Consequences of Converting Graded to Action Potentials upon Neural Information Coding and Energy Efficiency

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Sengupta, Biswa; Laughlin, Simon Barry; Niven, Jeremy Edward

2014-01-01

Information is encoded in neural circuits using both graded and action potentials, converting between them within single neurons and successive processing layers. This conversion is accompanied by information loss and a drop in energy efficiency. We investigate the biophysical causes of this loss of information and efficiency by comparing spiking neuron models, containing stochastic voltage-gated Na+ and K+ channels, with generator potential and graded potential models lacking voltage-gated Na+ channels. We identify three causes of information loss in the generator potential that are the by-product of action potential generation: (1) the voltage-gated Na+ channels necessary for action potential generation increase intrinsic noise and (2) introduce non-linearities, and (3) the finite duration of the action potential creates a ‘footprint’ in the generator potential that obscures incoming signals. These three processes reduce information rates by ∼50% in generator potentials, to ∼3 times that of spike trains. Both generator potentials and graded potentials consume almost an order of magnitude less energy per second than spike trains. Because of the lower information rates of generator potentials they are substantially less energy efficient than graded potentials. However, both are an order of magnitude more efficient than spike trains due to the higher energy costs and low information content of spikes, emphasizing that there is a two-fold cost of converting analogue to digital; information loss and cost inflation. PMID:24465197

Calcium-Induced calcium release during action potential firing in developing inner hair cells.

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Iosub, Radu; Avitabile, Daniele; Grant, Lisa; Tsaneva-Atanasova, Krasimira; Kennedy, Helen J

2015-03-10

In the mature auditory system, inner hair cells (IHCs) convert sound-induced vibrations into electrical signals that are relayed to the central nervous system via auditory afferents. Before the cochlea can respond to normal sound levels, developing IHCs fire calcium-based action potentials that disappear close to the onset of hearing. Action potential firing triggers transmitter release from the immature IHC that in turn generates experience-independent firing in auditory neurons. These early signaling events are thought to be essential for the organization and development of the auditory system and hair cells. A critical component of the action potential is the rise in intracellular calcium that activates both small conductance potassium channels essential during membrane repolarization, and triggers transmitter release from the cell. Whether this calcium signal is generated by calcium influx or requires calcium-induced calcium release (CICR) is not yet known. IHCs can generate CICR, but to date its physiological role has remained unclear. Here, we used high and low concentrations of ryanodine to block or enhance CICR to determine whether calcium release from intracellular stores affected action potential waveform, interspike interval, or changes in membrane capacitance during development of mouse IHCs. Blocking CICR resulted in mixed action potential waveforms with both brief and prolonged oscillations in membrane potential and intracellular calcium. This mixed behavior is captured well by our mathematical model of IHC electrical activity. We perform two-parameter bifurcation analysis of the model that predicts the dependence of IHCs firing patterns on the level of activation of two parameters, the SK2 channels activation and CICR rate. Our data show that CICR forms an important component of the calcium signal that shapes action potentials and regulates firing patterns, but is not involved directly in triggering exocytosis. These data provide important insights

Selective effects of potassium elevations on glutamate signaling and action potential conduction in hippocampus.

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Meeks, Julian P; Mennerick, Steven

2004-01-07

High-frequency synaptic transmission is depressed by moderate rises in the extracellular potassium concentration ([K+]o). Previous reports have indicated that depression of action potential signaling may underlie the synaptic depression. Here, we investigated the specific contribution of K+-induced action potential changes to synaptic depression. We found that glutamatergic transmission in the hippocampal area CA1 was significantly depressed by 8-10 mM [K+]o, but that GABAergic transmission remained intact. Riluzole, a drug that slows recovery from inactivation of voltage-gated sodium channels (NaChs), interacts with subthreshold [K+]o to depress afferent volleys and EPSCs strongly. Thus, elevated [K+]o likely depresses synapses by slowing NaCh recovery from inactivation. It is unclear from previous studies whether [K+]o-induced action potential depression is caused by changes in initiation, reliability, or waveform. We investigated these possibilities explicitly. [K+]o-induced afferent volley depression was independent of stimulus strength, suggesting that changes in action potential initiation do not explain [K+]o-induced depression. Measurements of action potentials from single axons revealed that 8 mM [K+]o increased conduction failures in a subpopulation of fibers and depressed action potential amplitude in all fibers. Together, these changes quantitatively account for the afferent volley depression. We estimate that conduction failure explains more than half of the synaptic depression observed at 8 mM [K+]o, with the remaining depression likely explained by waveform changes. These mechanisms of selective sensitivity of glutamate release to [K+]o accumulation represent a unique neuromodulatory mechanism and a brake on runaway excitation.

High-resolution three-dimensional mapping of semiconductor dopant potentials

DEFF Research Database (Denmark)

Twitchett, AC; Yates, TJV; Newcomb, SB

2007-01-01

Semiconductor device structures are becoming increasingly three-dimensional at the nanometer scale. A key issue that must be addressed to enable future device development is the three-dimensional mapping of dopant distributions, ideally under "working conditions". Here we demonstrate how a combin......Semiconductor device structures are becoming increasingly three-dimensional at the nanometer scale. A key issue that must be addressed to enable future device development is the three-dimensional mapping of dopant distributions, ideally under "working conditions". Here we demonstrate how...... a combination of electron holography and electron tomography can be used to determine quantitatively the three-dimensional electrostatic potential in an electrically biased semiconductor device with nanometer spatial resolution....

Compound sensory action potential in normal and pathological human nerves

DEFF Research Database (Denmark)

Krarup, Christian

2004-01-01

The compound sensory nerve action potential (SNAP) is the result of phase summation and cancellation of single fiber potentials (SFAPs) with amplitudes that depend on fiber diameter, and the amplitude and shape of the SNAP is determined by the distribution of fiber diameters. Conduction velocitie...... effort and attention to theory and practical detail that may be time consuming....

Directed fusion of cardiac spheroids into larger heterocellular microtissues enables investigation of cardiac action potential propagation via cardiac fibroblasts

Science.gov (United States)

Markes, Alexander R.; Okundaye, Amenawon O.; Qu, Zhilin; Mende, Ulrike; Choi, Bum-Rak

2018-01-01

Multicellular spheroids generated through cellular self-assembly provide cytoarchitectural complexities of native tissue including three-dimensionality, extensive cell-cell contacts, and appropriate cell-extracellular matrix interactions. They are increasingly suggested as building blocks for larger engineered tissues to achieve shapes, organization, heterogeneity, and other biomimetic complexities. Application of these tissue culture platforms is of particular importance in cardiac research as the myocardium is comprised of distinct but intermingled cell types. Here, we generated scaffold-free 3D cardiac microtissue spheroids comprised of cardiac myocytes (CMs) and/or cardiac fibroblasts (CFs) and used them as building blocks to form larger microtissues with different spatial distributions of CMs and CFs. Characterization of fusing homotypic and heterotypic spheroid pairs revealed an important influence of CFs on fusion kinetics, but most strikingly showed rapid fusion kinetics between heterotypic pairs consisting of one CF and one CM spheroid, indicating that CMs and CFs self-sort in vitro into the intermixed morphology found in the healthy myocardium. We then examined electrophysiological integration of fused homotypic and heterotypic microtissues by mapping action potential propagation. Heterocellular elongated microtissues which recapitulate the disproportionate CF spatial distribution seen in the infarcted myocardium showed that action potentials propagate through CF volumes albeit with significant delay. Complementary computational modeling revealed an important role of CF sodium currents and the spatial distribution of the CM-CF boundary in action potential conduction through CF volumes. Taken together, this study provides useful insights for the development of complex, heterocellular engineered 3D tissue constructs and their engraftment via tissue fusion and has implications for arrhythmogenesis in cardiac disease and repair. PMID:29715271

Directed fusion of cardiac spheroids into larger heterocellular microtissues enables investigation of cardiac action potential propagation via cardiac fibroblasts.

Directory of Open Access Journals (Sweden)

Tae Yun Kim

Full Text Available Multicellular spheroids generated through cellular self-assembly provide cytoarchitectural complexities of native tissue including three-dimensionality, extensive cell-cell contacts, and appropriate cell-extracellular matrix interactions. They are increasingly suggested as building blocks for larger engineered tissues to achieve shapes, organization, heterogeneity, and other biomimetic complexities. Application of these tissue culture platforms is of particular importance in cardiac research as the myocardium is comprised of distinct but intermingled cell types. Here, we generated scaffold-free 3D cardiac microtissue spheroids comprised of cardiac myocytes (CMs and/or cardiac fibroblasts (CFs and used them as building blocks to form larger microtissues with different spatial distributions of CMs and CFs. Characterization of fusing homotypic and heterotypic spheroid pairs revealed an important influence of CFs on fusion kinetics, but most strikingly showed rapid fusion kinetics between heterotypic pairs consisting of one CF and one CM spheroid, indicating that CMs and CFs self-sort in vitro into the intermixed morphology found in the healthy myocardium. We then examined electrophysiological integration of fused homotypic and heterotypic microtissues by mapping action potential propagation. Heterocellular elongated microtissues which recapitulate the disproportionate CF spatial distribution seen in the infarcted myocardium showed that action potentials propagate through CF volumes albeit with significant delay. Complementary computational modeling revealed an important role of CF sodium currents and the spatial distribution of the CM-CF boundary in action potential conduction through CF volumes. Taken together, this study provides useful insights for the development of complex, heterocellular engineered 3D tissue constructs and their engraftment via tissue fusion and has implications for arrhythmogenesis in cardiac disease and repair.

Contribution mapping: a method for mapping the contribution of research to enhance its impact

Science.gov (United States)

2012-01-01

Background At a time of growing emphasis on both the use of research and accountability, it is important for research funders, researchers and other stakeholders to monitor and evaluate the extent to which research contributes to better action for health, and find ways to enhance the likelihood that beneficial contributions are realized. Past attempts to assess research 'impact' struggle with operationalizing 'impact', identifying the users of research and attributing impact to research projects as source. In this article we describe Contribution Mapping, a novel approach to research monitoring and evaluation that aims to assess contributions instead of impacts. The approach focuses on processes and actors and systematically assesses anticipatory efforts that aim to enhance contributions, so-called alignment efforts. The approach is designed to be useful for both accountability purposes and for assisting in better employing research to contribute to better action for health. Methods Contribution Mapping is inspired by a perspective from social studies of science on how research and knowledge utilization processes evolve. For each research project that is assessed, a three-phase process map is developed that includes the main actors, activities and alignment efforts during research formulation, production and knowledge extension (e.g. dissemination and utilization). The approach focuses on the actors involved in, or interacting with, a research project (the linked actors) and the most likely influential users, who are referred to as potential key users. In the first stage, the investigators of the assessed project are interviewed to develop a preliminary version of the process map and first estimation of research-related contributions. In the second stage, potential key-users and other informants are interviewed to trace, explore and triangulate possible contributions. In the third stage, the presence and role of alignment efforts is analyzed and the preliminary

Mapping potential acid sulfate soils in Denmark using legacy data and LiDAR-based derivatives

DEFF Research Database (Denmark)

Beucher, Amélie; Adhikari, Kabindra; Breuning-Madsen, Henrik

2017-01-01

drainage of areas classified as potential a.s. soilswithout prior permission fromenvironmental authorities. Themapping of these soils was first conducted in the 1980’s.Wetlands, inwhich Danish potential a.s. soils mostly occur,were targeted and the soilswere surveyed through conventional mapping....... In this study, a probability map for potential a.s. soil occurrence was constructed for thewetlands located in Jutland, Denmark (c. 6500 km2), using the digital soilmapping (DSM) approach. Among the variety of available DSM techniques, artificial neural networks (ANNs) were selected. More than 8000 existing...... of environmental variables. The overall prediction accuracy based on a 30% hold-back validation data reached 70%. Furthermore, the conventional map indicated 32% of the study area (c. 2100 km2) as having a high frequency for potential a.s. soils while the digital map displayed about 46% (c. 3000 km2) as high...

Autism and Intellectual Disability-Associated KIRREL3 Interacts with Neuronal Proteins MAP1B and MYO16 with Potential Roles in Neurodevelopment.

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Ying F Liu

Full Text Available Cell-adhesion molecules of the immunoglobulin superfamily play critical roles in brain development, as well as in maintaining synaptic plasticity, the dysfunction of which is known to cause cognitive impairment. Recently dysfunction of KIRREL3, a synaptic molecule of the immunoglobulin superfamily, has been implicated in several neurodevelopmental conditions including intellectual disability, autism spectrum disorder, and in the neurocognitive delay associated with Jacobsen syndrome. However, the molecular mechanisms of its physiological actions remain largely unknown. Using a yeast two-hybrid screen, we found that the KIRREL3 extracellular domain interacts with brain expressed proteins MAP1B and MYO16 and its intracellular domain can potentially interact with ATP1B1, UFC1, and SHMT2. The interactions were confirmed by co-immunoprecipitation and colocalization analyses of proteins expressed in human embryonic kidney cells, mouse neuronal cells, and rat primary neuronal cells. Furthermore, we show KIRREL3 colocalization with the marker for the Golgi apparatus and synaptic vesicles. Previously, we have shown that KIRREL3 interacts with the X-linked intellectual disability associated synaptic scaffolding protein CASK through its cytoplasmic domain. In addition, we found a genomic deletion encompassing MAP1B in one patient with intellectual disability, microcephaly and seizures and deletions encompassing MYO16 in two unrelated patients with intellectual disability, autism and microcephaly. MAP1B has been previously implicated in synaptogenesis and is involved in the development of the actin-based membrane skeleton. MYO16 is expressed in hippocampal neurons and also indirectly affects actin cytoskeleton through its interaction with WAVE1 complex. We speculate KIRREL3 interacting proteins are potential candidates for intellectual disability and autism spectrum disorder. Moreover, our findings provide further insight into understanding the molecular

Corrected body surface potential mapping.

Science.gov (United States)

Krenzke, Gerhard; Kindt, Carsten; Hetzer, Roland

2007-02-01

In the method for body surface potential mapping described here, the influence of thorax shape on measured ECG values is corrected. The distances of the ECG electrodes from the electrical heart midpoint are determined using a special device for ECG recording. These distances are used to correct the ECG values as if they had been measured on the surface of a sphere with a radius of 10 cm with its midpoint localized at the electrical heart midpoint. The equipotential lines of the electrical heart field are represented on the virtual surface of such a sphere. It is demonstrated that the character of a dipole field is better represented if the influence of the thorax shape is reduced. The site of the virtual reference electrode is also important for the dipole character of the representation of the electrical heart field.

Dynamics of the inward rectifier K+ current during the action potential of guinea pig ventricular myocytes

OpenAIRE

Ibarra, J.; Morley, G.E.; Delmar, M.

1991-01-01

The potassium selective, inward rectifier current (IK1) is known to be responsible for maintaining the resting membrane potential of quiescent ventricular myocytes. However, the contribution of this current to the different phases of the cardiac action potential has not been adequately established. In the present study, we have used the action potential clamp (APC) technique to characterize the dynamic changes of a cesium-sensitive (i.e., Ik1) current which occur during the action potential. ...

Restitution slope is principally determined by steady-state action potential duration.

Science.gov (United States)

Shattock, Michael J; Park, Kyung Chan; Yang, Hsiang-Yu; Lee, Angela W C; Niederer, Steven; MacLeod, Kenneth T; Winter, James

2017-06-01

The steepness of the action potential duration (APD) restitution curve and local tissue refractoriness are both thought to play important roles in arrhythmogenesis. Despite this, there has been little recognition of the apparent association between steady-state APD and the slope of the restitution curve. The objective of this study was to test the hypothesis that restitution slope is determined by APD and to examine the relationship between restitution slope, refractoriness and susceptibility to VF. Experiments were conducted in isolated hearts and ventricular myocytes from adult guinea pigs and rabbits. Restitution curves were measured under control conditions and following intervention to prolong (clofilium, veratridine, bretylium, low [Ca]e, chronic transverse aortic constriction) or shorten (catecholamines, rapid pacing) ventricular APD. Despite markedly differing mechanisms of action, all interventions that prolonged the action potential led to a steepening of the restitution curve (and vice versa). Normalizing the restitution curve as a % of steady-state APD abolished the difference in restitution curves with all interventions. Effects on restitution were preserved when APD was modulated by current injection in myocytes pre-treated with the calcium chelator BAPTA-AM - to abolish the intracellular calcium transient. The non-linear relation between APD and the rate of repolarization of the action potential is shown to underpin the common influence of APD on the slope of the restitution curve. Susceptibility to VF was found to parallel changes in APD/refractoriness, rather than restitution slope. Steady-state APD is the principal determinant of the slope of the ventricular electrical restitution curve. In the absence of post-repolarization refractoriness, factors that prolong the action potential would be expected to steepen the restitution curve. However, concomitant changes in tissue refractoriness act to reduce susceptibility to sustained VF. Dependence on

[Effects of dauricine on action potentials and slow inward currents of guinea pig ventricular papillary muscles].

Science.gov (United States)

Li, S N; Zhang, K Y

1992-11-01

Effects of dauricine (Dau) on the action potentials (AP), the slow action potentials (SAP), and the slow inward currents (Isi) of guinea pig ventricular papillary muscles were observed by means of intracellular microelectrode and single sucrose gap voltage clamp technique. In the early stage, Dau shortened action potential duration 100 (APD100) and effective refractory period (ERP) (ERP/APD ERP, and APD20, significantly decreased action potential amplitude (APA), maximum velocity (Vmax), and overshot (OS) (ERP/APD > 1; P SAP induced by isoprenaline (P < 0.01), and remarkably inhibited Isi (P < 0.01). The results suggested that Dau exerted an inhibitory effect on Na+, Ca2+, and K+ channels.

SAR China Land Mapping Project: Development, Production and Potential Applications

International Nuclear Information System (INIS)

Zhang, Lu; Guo, Huadong; Liu, Guang; Fu, Wenxue; Yan, Shiyong; Song, Rui; Ji, Peng; Wang, Xinyuan

2014-01-01

Large-area, seamless synthetic aperture radar (SAR) mosaics can reflect overall environmental conditions and highlight general trends in observed areas from a macroscopic standpoint, and effectively support research at the global scale, which is in high demand now across scientific fields. The SAR China Land Mapping Project (SCLM), supported by the Digital Earth Science Platform Project initiated and managed by the Center for Earth Observation and Digital Earth, Chinese Academy of Sciences (CEODE), is introduced in this paper. This project produced a large-area SAR mosaic dataset and generated the first complete seamless SAR map covering the entire land area of China using EnviSat-ASAR images. The value of the mosaic map is demonstrated by some potential applications in studies of urban distribution, rivers and lakes, geologic structures, geomorphology and paleoenvironmental change

Position-dependent patterning of spontaneous action potentials in immature cochlear inner hair cells.

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Johnson, Stuart L; Eckrich, Tobias; Kuhn, Stephanie; Zampini, Valeria; Franz, Christoph; Ranatunga, Kishani M; Roberts, Terri P; Masetto, Sergio; Knipper, Marlies; Kros, Corné J; Marcotti, Walter

2011-06-01

Spontaneous action potential activity is crucial for mammalian sensory system development. In the auditory system, patterned firing activity has been observed in immature spiral ganglion and brain-stem neurons and is likely to depend on cochlear inner hair cell (IHC) action potentials. It remains uncertain whether spiking activity is intrinsic to developing IHCs and whether it shows patterning. We found that action potentials were intrinsically generated by immature IHCs of altricial rodents and that apical IHCs showed bursting activity as opposed to more sustained firing in basal cells. We show that the efferent neurotransmitter acetylcholine fine-tunes the IHC's resting membrane potential (V(m)), and as such is crucial for the bursting pattern in apical cells. Endogenous extracellular ATP also contributes to the V(m) of apical and basal IHCs by triggering small-conductance Ca(2+)-activated K(+) (SK2) channels. We propose that the difference in firing pattern along the cochlea instructs the tonotopic differentiation of IHCs and auditory pathway.

Position-dependent patterning of spontaneous action potentials in immature cochlear inner hair cells

Science.gov (United States)

Johnson, Stuart L.; Eckrich, Tobias; Kuhn, Stephanie; Zampini, Valeria; Franz, Christoph; Ranatunga, Kishani M.; Roberts, Terri P.; Masetto, Sergio; Knipper, Marlies; Kros, Corné J.; Marcotti, Walter

2011-01-01

Spontaneous action potential activity is crucial for mammalian sensory system development. In the auditory system, patterned firing activity has been observed in immature spiral ganglion cells and brain-stem neurons and is likely to depend on cochlear inner hair cell (IHC) action potentials. It remains uncertain whether spiking activity is intrinsic to developing IHCs and whether it shows patterning. We found that action potentials are intrinsically generated by immature IHCs of altricial rodents and that apical IHCs exhibit bursting activity as opposed to more sustained firing in basal cells. We show that the efferent neurotransmitter ACh, by fine-tuning the IHC’s resting membrane potential (Vm), is crucial for the bursting pattern in apical cells. Endogenous extracellular ATP also contributes to the Vm of apical and basal IHCs by activating SK2 channels. We hypothesize that the difference in firing pattern along the cochlea instructs the tonotopic differentiation of IHCs and auditory pathway. PMID:21572434

Effects of Acetylcholine and Noradrenalin on Action Potentials of Isolated Rabbit Sinoatrial and Atrial Myocytes

Science.gov (United States)

Verkerk, Arie O.; Geuzebroek, Guillaume S. C.; Veldkamp, Marieke W.; Wilders, Ronald

2012-01-01

The autonomic nervous system controls heart rate and contractility through sympathetic and parasympathetic inputs to the cardiac tissue, with acetylcholine (ACh) and noradrenalin (NA) as the chemical transmitters. In recent years, it has become clear that specific Regulators of G protein Signaling proteins (RGS proteins) suppress muscarinic sensitivity and parasympathetic tone, identifying RGS proteins as intriguing potential therapeutic targets. In the present study, we have identified the effects of 1 μM ACh and 1 μM NA on the intrinsic action potentials of sinoatrial (SA) nodal and atrial myocytes. Single cells were enzymatically isolated from the SA node or from the left atrium of rabbit hearts. Action potentials were recorded using the amphotericin-perforated patch-clamp technique in the absence and presence of ACh, NA, or a combination of both. In SA nodal myocytes, ACh increased cycle length and decreased diastolic depolarization rate, whereas NA decreased cycle length and increased diastolic depolarization rate. Both ACh and NA increased maximum upstroke velocity. Furthermore, ACh hyperpolarized the maximum diastolic potential. In atrial myocytes stimulated at 2 Hz, both ACh and NA hyperpolarized the maximum diastolic potential, increased the action potential amplitude, and increased the maximum upstroke velocity. Action potential duration at 50 and 90% repolarization was decreased by ACh, but increased by NA. The effects of both ACh and NA on action potential duration showed a dose dependence in the range of 1–1000 nM, while a clear-cut frequency dependence in the range of 1–4 Hz was absent. Intermediate results were obtained in the combined presence of ACh and NA in both SA nodal and atrial myocytes. Our data uncover the extent to which SA nodal and atrial action potentials are intrinsically dependent on ACh, NA, or a combination of both and may thus guide further experiments with RGS proteins. PMID:22754533

Implementing participatory action research in Lithuania: potential and challenges

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Gabija Jarašiūnaitė

2015-12-01

Full Text Available Participatory action research is a quite new approach to research in Lithuania. The aim of an article was to disscuss the potential and challenges of participatory action research while implementing it in Lithuanian organizations. The qualitative approach was chosen for the study using the method of Focus groups. 20 researchers from social and biomedicine sciences from six institutions of High education in Lithuania participated in the study. The results of the study showed that participatory action reasearch is seen as an approach with many possibilities because of a wide range of used methods, constant interactions with research participants and the lenght of the research process. Researchers value the possibility to access organization at the begining, during research process and evaluate the effectiveness of the changes after the process. The research challenges are associated with the competence of a researcher including his/her sensitivity during process, ability to involve active participation of organization members in the ongoing process by creating safe and trusting environment. Some specific challenges associated with Lithuanian organizations are organizations‘ tiredness of researches and lack of faith of the benefits of researches because of some previous experiences. Keywords: Participatory Action Research, Organization, Lithuania.

Manifestation of an Analytic Hierarchy Process (AHP Model on Fire Potential Zonation Mapping in Kathmandu Metropolitan City, Nepal

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Sachin Kumar Chhetri

2015-03-01

Full Text Available Even though fewer people die as a result of fire than other natural disasters, such as earthquake, flood, landslide, etc., the average loss of property due to fire is high. Kathmandu Metropolitan City is becoming more vulnerable to fire due to haphazard urbanization and increase in population. To control problems due to fire, systematic studies are necessary, including fire potential mapping and risk assessment. This study applies an Analytic Hierarchy Process (AHP method in Kathmandu Metropolitan City, Nepal for generation of fire potential zonation map. The fire potential zonation map is prepared on the basis of available data of land use, fuel stations, and population density. This map shows that 58.04% of the study area falls under low fire potential zone, 32.92% falls under moderate fire potential zone and 9.04% falls under high fire potential zone. The map is also validated through major past fire incidents. The results show that the predicted fire potential zones are found to be in good agreement with past fire incidents, and, hence, the map can be used for future land-use planning.

ACTION-SPACE CLUSTERING OF TIDAL STREAMS TO INFER THE GALACTIC POTENTIAL

Energy Technology Data Exchange (ETDEWEB)

Sanderson, Robyn E.; Helmi, Amina [Kapteyn Astronomical Institute, P.O. Box 800, 9700 AV Groningen (Netherlands); Hogg, David W., E-mail: robyn@astro.columbia.edu [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States)

2015-03-10

We present a new method for constraining the Milky Way halo gravitational potential by simultaneously fitting multiple tidal streams. This method requires three-dimensional positions and velocities for all stars to be fit, but does not require identification of any specific stream or determination of stream membership for any star. We exploit the principle that the action distribution of stream stars is most clustered when the potential used to calculate the actions is closest to the true potential. Clustering is quantified with the Kullback-Leibler Divergence (KLD), which also provides conditional uncertainties for our parameter estimates. We show, for toy Gaia-like data in a spherical isochrone potential, that maximizing the KLD of the action distribution relative to a smoother distribution recovers the input potential. The precision depends on the observational errors and number of streams; using K III giants as tracers, we measure the enclosed mass at the average radius of the sample stars accurate to 3% and precise to 20%-40%. Recovery of the scale radius is precise to 25%, biased 50% high by the small galactocentric distance range of stars in our mock sample (1-25 kpc, or about three scale radii, with mean 6.5 kpc). 20-25 streams with at least 100 stars each are required for a stable confidence interval. With radial velocities (RVs) to 100 kpc, all parameters are determined with ∼10% accuracy and 20% precision (1.3% accuracy for the enclosed mass), underlining the need to complete the RV catalog for faint halo stars observed by Gaia.

Neuronal oscillations enhance stimulus discrimination by ensuring action potential precision

DEFF Research Database (Denmark)

Schaefer, Andreas T; Angelo, Kamilla; Spors, Hartwig

2006-01-01

generated membrane potential oscillations dramatically improve action potential (AP) precision by removing the membrane potential variance associated with jitter-accumulating trains of APs. This increased AP precision occurred irrespective of cell type and--at oscillation frequencies ranging from 3 to 65 Hz......Although oscillations in membrane potential are a prominent feature of sensory, motor, and cognitive function, their precise role in signal processing remains elusive. Here we show, using a combination of in vivo, in vitro, and theoretical approaches, that both synaptically and intrinsically......, membrane potential oscillations dramatically enhance the discriminatory capabilities of individual neurons and networks of cells and provide one attractive explanation for their abundance in neurophysiological systems....

Action Potential Dynamics in Fine Axons Probed with an Axonally Targeted Optical Voltage Sensor.

Science.gov (United States)

Ma, Yihe; Bayguinov, Peter O; Jackson, Meyer B

2017-01-01

The complex and malleable conduction properties of axons determine how action potentials propagate through extensive axonal arbors to reach synaptic terminals. The excitability of axonal membranes plays a major role in neural circuit function, but because most axons are too thin for conventional electrical recording, their properties remain largely unexplored. To overcome this obstacle, we used a genetically encoded hybrid voltage sensor (hVOS) harboring an axonal targeting motif. Expressing this probe in transgenic mice enabled us to monitor voltage changes optically in two populations of axons in hippocampal slices, the large axons of dentate granule cells (mossy fibers) in the stratum lucidum of the CA3 region and the much finer axons of hilar mossy cells in the inner molecular layer of the dentate gyrus. Action potentials propagated with distinct velocities in each type of axon. Repetitive firing broadened action potentials in both populations, but at an intermediate frequency the degree of broadening differed. Repetitive firing also attenuated action potential amplitudes in both mossy cell and granule cell axons. These results indicate that the features of use-dependent action potential broadening, and possible failure, observed previously in large nerve terminals also appear in much finer unmyelinated axons. Subtle differences in the frequency dependences could influence the propagation of activity through different pathways to excite different populations of neurons. The axonally targeted hVOS probe used here opens up the diverse repertoire of neuronal processes to detailed biophysical study.

Probabilistic Flood Maps to support decision-making: Mapping the Value of Information

Science.gov (United States)

Alfonso, L.; Mukolwe, M. M.; Di Baldassarre, G.

2016-02-01

Floods are one of the most frequent and disruptive natural hazards that affect man. Annually, significant flood damage is documented worldwide. Flood mapping is a common preimpact flood hazard mitigation measure, for which advanced methods and tools (such as flood inundation models) are used to estimate potential flood extent maps that are used in spatial planning. However, these tools are affected, largely to an unknown degree, by both epistemic and aleatory uncertainty. Over the past few years, advances in uncertainty analysis with respect to flood inundation modeling show that it is appropriate to adopt Probabilistic Flood Maps (PFM) to account for uncertainty. However, the following question arises; how can probabilistic flood hazard information be incorporated into spatial planning? Thus, a consistent framework to incorporate PFMs into the decision-making is required. In this paper, a novel methodology based on Decision-Making under Uncertainty theories, in particular Value of Information (VOI) is proposed. Specifically, the methodology entails the use of a PFM to generate a VOI map, which highlights floodplain locations where additional information is valuable with respect to available floodplain management actions and their potential consequences. The methodology is illustrated with a simplified example and also applied to a real case study in the South of France, where a VOI map is analyzed on the basis of historical land use change decisions over a period of 26 years. Results show that uncertain flood hazard information encapsulated in PFMs can aid decision-making in floodplain planning.

Mapping human brain networks with cortico-cortical evoked potentials

Science.gov (United States)

Keller, Corey J.; Honey, Christopher J.; Mégevand, Pierre; Entz, Laszlo; Ulbert, Istvan; Mehta, Ashesh D.

2014-01-01

The cerebral cortex forms a sheet of neurons organized into a network of interconnected modules that is highly expanded in humans and presumably enables our most refined sensory and cognitive abilities. The links of this network form a fundamental aspect of its organization, and a great deal of research is focusing on understanding how information flows within and between different regions. However, an often-overlooked element of this connectivity regards a causal, hierarchical structure of regions, whereby certain nodes of the cortical network may exert greater influence over the others. While this is difficult to ascertain non-invasively, patients undergoing invasive electrode monitoring for epilepsy provide a unique window into this aspect of cortical organization. In this review, we highlight the potential for cortico-cortical evoked potential (CCEP) mapping to directly measure neuronal propagation across large-scale brain networks with spatio-temporal resolution that is superior to traditional neuroimaging methods. We first introduce effective connectivity and discuss the mechanisms underlying CCEP generation. Next, we highlight how CCEP mapping has begun to provide insight into the neural basis of non-invasive imaging signals. Finally, we present a novel approach to perturbing and measuring brain network function during cognitive processing. The direct measurement of CCEPs in response to electrical stimulation represents a potentially powerful clinical and basic science tool for probing the large-scale networks of the human cerebral cortex. PMID:25180306

Arsenic Trioxide Modulates the Central Snail Neuron Action Potential

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Guan-Ling Lu

2009-09-01

Conclusion: As2O3 at 10 mM elicits BoPs in central snail neurons and this effect may relate to the PLC activity of the neuron, rather than protein kinase A activity, or calcium influxes of the neuron. As2O3 at higher concentration irreversibly abolishes the spontaneous action potentials of the neuron.

Action potentials and ion conductances in wild-type and CALHM1-knockout type II taste cells

Science.gov (United States)

Saung, Wint Thu; Foskett, J. Kevin

2017-01-01

Taste bud type II cells fire action potentials in response to tastants, triggering nonvesicular ATP release to gustatory neurons via voltage-gated CALHM1-associated ion channels. Whereas CALHM1 regulates mouse cortical neuron excitability, its roles in regulating type II cell excitability are unknown. In this study, we compared membrane conductances and action potentials in single identified TRPM5-GFP-expressing circumvallate papillae type II cells acutely isolated from wild-type (WT) and Calhm1 knockout (KO) mice. The activation kinetics of large voltage-gated outward currents were accelerated in cells from Calhm1 KO mice, and their associated nonselective tail currents, previously shown to be highly correlated with ATP release, were completely absent in Calhm1 KO cells, suggesting that CALHM1 contributes to all of these currents. Calhm1 deletion did not significantly alter resting membrane potential or input resistance, the amplitudes and kinetics of Na+ currents either estimated from action potentials or recorded from steady-state voltage pulses, or action potential threshold, overshoot peak, afterhyperpolarization, and firing frequency. However, Calhm1 deletion reduced the half-widths of action potentials and accelerated the deactivation kinetics of transient outward currents, suggesting that the CALHM1-associated conductance becomes activated during the repolarization phase of action potentials. NEW & NOTEWORTHY CALHM1 is an essential ion channel component of the ATP neurotransmitter release mechanism in type II taste bud cells. Its contribution to type II cell resting membrane properties and excitability is unknown. Nonselective voltage-gated currents, previously associated with ATP release, were absent in cells lacking CALHM1. Calhm1 deletion was without effects on resting membrane properties or voltage-gated Na+ and K+ channels but contributed modestly to the kinetics of action potentials. PMID:28202574

Neuroanatomical substrates of action perception and understanding: an anatomic likelihood estimation meta-analysis of lesion-symptom mapping studies in brain injured patients.

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Cosimo eUrgesi

2014-05-01

Full Text Available Several neurophysiologic and neuroimaging studies suggested that motor and perceptual systems are tightly linked along a continuum rather than providing segregated mechanisms supporting different functions. Using correlational approaches, these studies demonstrated that action observation activates not only visual but also motor brain regions. On the other hand, brain stimulation and brain lesion evidence allows tackling the critical question of whether our action representations are necessary to perceive and understand others’ actions. In particular, recent neuropsychological studies have shown that patients with temporal, parietal and frontal lesions exhibit a number of possible deficits in the visual perception and the understanding of others’ actions. The specific anatomical substrates of such neuropsychological deficits however are still a matter of debate. Here we review the existing literature on this issue and perform an anatomic likelihood estimation meta-analysis of studies using lesion-symptom mapping methods on the causal relation between brain lesions and non-linguistic action perception and understanding deficits. The meta-analysis encompassed data from 361 patients tested in 11 studies and identified regions in the inferior frontal cortex, the inferior parietal cortex and the middle/superior temporal cortex, whose damage is consistently associated with poor performance in action perception and understanding tasks across studies. Interestingly, these areas correspond to the three nodes of the action observation network that are strongly activated in response to visual action perception in neuroimaging research and that have been targeted in previous brain stimulation studies. Thus, brain lesion mapping research provides converging causal evidence that premotor, parietal and temporal regions play a crucial role in action recognition and understanding.

Population of computational rabbit-specific ventricular action potential models for investigating sources of variability in cellular repolarisation.

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Philip Gemmell

Full Text Available Variability is observed at all levels of cardiac electrophysiology. Yet, the underlying causes and importance of this variability are generally unknown, and difficult to investigate with current experimental techniques. The aim of the present study was to generate populations of computational ventricular action potential models that reproduce experimentally observed intercellular variability of repolarisation (represented by action potential duration and to identify its potential causes. A systematic exploration of the effects of simultaneously varying the magnitude of six transmembrane current conductances (transient outward, rapid and slow delayed rectifier K(+, inward rectifying K(+, L-type Ca(2+, and Na(+/K(+ pump currents in two rabbit-specific ventricular action potential models (Shannon et al. and Mahajan et al. at multiple cycle lengths (400, 600, 1,000 ms was performed. This was accomplished with distributed computing software specialised for multi-dimensional parameter sweeps and grid execution. An initial population of 15,625 parameter sets was generated for both models at each cycle length. Action potential durations of these populations were compared to experimentally derived ranges for rabbit ventricular myocytes. 1,352 parameter sets for the Shannon model and 779 parameter sets for the Mahajan model yielded action potential duration within the experimental range, demonstrating that a wide array of ionic conductance values can be used to simulate a physiological rabbit ventricular action potential. Furthermore, by using clutter-based dimension reordering, a technique that allows visualisation of multi-dimensional spaces in two dimensions, the interaction of current conductances and their relative importance to the ventricular action potential at different cycle lengths were revealed. Overall, this work represents an important step towards a better understanding of the role that variability in current conductances may play in

Population of computational rabbit-specific ventricular action potential models for investigating sources of variability in cellular repolarisation.

Science.gov (United States)

Gemmell, Philip; Burrage, Kevin; Rodriguez, Blanca; Quinn, T Alexander

2014-01-01

Variability is observed at all levels of cardiac electrophysiology. Yet, the underlying causes and importance of this variability are generally unknown, and difficult to investigate with current experimental techniques. The aim of the present study was to generate populations of computational ventricular action potential models that reproduce experimentally observed intercellular variability of repolarisation (represented by action potential duration) and to identify its potential causes. A systematic exploration of the effects of simultaneously varying the magnitude of six transmembrane current conductances (transient outward, rapid and slow delayed rectifier K(+), inward rectifying K(+), L-type Ca(2+), and Na(+)/K(+) pump currents) in two rabbit-specific ventricular action potential models (Shannon et al. and Mahajan et al.) at multiple cycle lengths (400, 600, 1,000 ms) was performed. This was accomplished with distributed computing software specialised for multi-dimensional parameter sweeps and grid execution. An initial population of 15,625 parameter sets was generated for both models at each cycle length. Action potential durations of these populations were compared to experimentally derived ranges for rabbit ventricular myocytes. 1,352 parameter sets for the Shannon model and 779 parameter sets for the Mahajan model yielded action potential duration within the experimental range, demonstrating that a wide array of ionic conductance values can be used to simulate a physiological rabbit ventricular action potential. Furthermore, by using clutter-based dimension reordering, a technique that allows visualisation of multi-dimensional spaces in two dimensions, the interaction of current conductances and their relative importance to the ventricular action potential at different cycle lengths were revealed. Overall, this work represents an important step towards a better understanding of the role that variability in current conductances may play in experimentally

Mapping the environmental risk potential on surface water of pesticide contamination in the Prosecco's vineyard terraced landscape

Science.gov (United States)

Pizarro, Patricia; Ferrarese, Francesco; Loddo, Donato; Eugenio Pappalardo, Salvatore; Varotto, Mauro

2016-04-01

Intensive cropping systems today represent a paramount issue in terms of environmental impacts, since agricultural pollutants can constitute a potential threat to surface water, non-target organisms and aquatic ecosystems. Levels of pesticide concentrations in surface waters are indeed unquestionably correlated to crop and soil management practices at field-scale. Due to the numerous applications of pesticides required, orchards and vineyards can represent relevant non-point sources for pesticide contamination of water bodies, mainly prompted by soil erosion, surface runoff and spray drift. To reduce risks of pesticide contamination of surface water, the Directive 2009/128/CET imposed the local implementation of agricultural good practices and mitigation actions such as the use of vegetative buffer filter strips and hedgerows along river and pond banks. However, implementation of mitigation actions is often difficult, especially in extremely fragmented agricultural landscapes characterized by a complex territorial matrix set up on urban sprawling, frequent surface water bodies, important geomorphological processes and protected natural areas. Typically, such landscape matrix is well represented by the, Prosecco-DOCG vineyards area (NE of Italy, Province of Treviso) which lays on hogback hills of conglomerate, marls and sandstone that ranges between 50 and 500 m asl. Moreover such vineyards landscape is characterized by traditional and non-traditional agricultural terraces The general aim of this paper is to identify areas of surface water bodies with high potential risk of pesticide contamination from surrounding vineyards in the 735 ha of Lierza river basin (Refrontolo, TV), one of the most representative terraced landscape of the Prosecco-DOCG area. Specific aims are i) mapping terraced Prosecco-DOCG vineyards, ii) classifying potential risk from pesticide of the different areas. Remote sensing technologies such as four bands aerial photos (RGB+NIR) and Light

State and location dependence of action potential metabolic cost in cortical pyramidal neurons

NARCIS (Netherlands)

Hallermann, Stefan; de Kock, Christiaan P. J.; Stuart, Greg J.; Kole, Maarten H. P.

2012-01-01

Action potential generation and conduction requires large quantities of energy to restore Na+ and K+ ion gradients. We investigated the subcellular location and voltage dependence of this metabolic cost in rat neocortical pyramidal neurons. Using Na+/K+ charge overlap as a measure of action

State and location dependence of action potential metabolic cost in cortical pyramidal neurons

NARCIS (Netherlands)

Hallermann, S.; de Kock, C.P.J.; Stuart, G.J.; Kole, M.H.

2012-01-01

Action potential generation and conduction requires large quantities of energy to restore Na + and K + ion gradients. We investigated the subcellular location and voltage dependence of this metabolic cost in rat neocortical pyramidal neurons. Using Na +K + charge overlap as a measure of action

Effects of pioglitazone on cardiac ion currents and action potential morphology in canine ventricular myocytes.

Science.gov (United States)

Kistamás, Kornél; Szentandrássy, Norbert; Hegyi, Bence; Ruzsnavszky, Ferenc; Váczi, Krisztina; Bárándi, László; Horváth, Balázs; Szebeni, Andrea; Magyar, János; Bányász, Tamás; Kecskeméti, Valéria; Nánási, Péter P

2013-06-15

Despite its widespread therapeutical use there is little information on the cellular cardiac effects of the antidiabetic drug pioglitazone in larger mammals. In the present study, therefore, the concentration-dependent effects of pioglitazone on ion currents and action potential configuration were studied in isolated canine ventricular myocytes using standard microelectrode, conventional whole cell patch clamp, and action potential voltage clamp techniques. Pioglitazone decreased the maximum velocity of depolarization and the amplitude of phase-1 repolarization at concentrations ≥3 μM. Action potentials were shortened by pioglitazone at concentrations ≥10 μM, which effect was accompanied with significant reduction of beat-to-beat variability of action potential duration. Several transmembrane ion currents, including the transient outward K(+) current (Ito), the L-type Ca(2+) current (ICa), the rapid and slow components of the delayed rectifier K(+) current (IKr and IKs, respectively), and the inward rectifier K(+) current (IK1) were inhibited by pioglitazone under conventional voltage clamp conditions. Ito was blocked significantly at concentrations ≥3 μM, ICa, IKr, IKs at concentrations ≥10 μM, while IK1 at concentrations ≥30 μM. Suppression of Ito, ICa, IKr, and IK1 has been confirmed also under action potential voltage clamp conditions. ATP-sensitive K(+) current, when activated by lemakalim, was effectively blocked by pioglitazone. Accordingly, action potentials were prolonged by 10 μM pioglitazone when the drug was applied in the presence of lemakalim. All these effects developed rapidly and were readily reversible upon washout. In conclusion, pioglitazone seems to be a harmless agent at usual therapeutic concentrations. Copyright © 2013 Elsevier B.V. All rights reserved.

Granger causality mapping during joint actions reveals evidence for forward models that could overcome sensory-motor delays.

Directory of Open Access Journals (Sweden)

Idil Kokal

Full Text Available Studies investigating joint actions have suggested a central role for the putative mirror neuron system (pMNS because of the close link between perception and action provided by these brain regions [1], [2], [3]. In contrast, our previous functional magnetic resonance imaging (fMRI experiment demonstrated that the BOLD response of the pMNS does not suggest that it directly integrates observed and executed actions during joint actions [4]. To test whether the pMNS might contribute indirectly to the integration process by sending information to brain areas responsible for this integration (integration network, here we used Granger causality mapping (GCM [5]. We explored the directional information flow between the anterior sites of the pMNS and previously identified integrative brain regions. We found that the left BA44 sent more information than it received to both the integration network (left thalamus, right middle occipital gyrus and cerebellum and more posterior nodes of the pMNS (BA2. Thus, during joint actions, two anatomically separate networks therefore seem effectively connected and the information flow is predominantly from anterior to posterior areas of the brain. These findings suggest that the pMNS is involved indirectly in joint actions by transforming observed and executed actions into a common code and is part of a generative model that could predict the future somatosensory and visual consequences of observed and executed actions in order to overcome otherwise inevitable neural delays.

Mapping the geogenic radon potential: methodology and spatial analysis for central Hungary

International Nuclear Information System (INIS)

Szabó, Katalin Zsuzsanna; Jordan, Gyozo; Horváth, Ákos; Szabó, Csaba

2014-01-01

A detailed geogenic radon potential (GRP) mapping based on field soil gas radon and soil gas permeability measurements was carried out in this study. A conventional continuous variable approach was used in this study for GRP determination and to test its applicability to the selected area of Hungary. Spatial pattern of soil gas radon concentration, soil permeability and GRP and the relationship between geological formations and these parameters were studied by performing detailed spatial analysis. Exploratory data analysis revealed that higher soil gas radon activity concentration and GRP characterizes the mountains and hills than the plains. The highest values were found in the proluvial–deluvial sediments, rock debris on the downhill slopes eroded from hills. Among the Quaternary sediments, which characterize the study area, the fluvial sediment has the highest values, which are also located in the hilly areas. The lowest values were found in the plain areas covered by drift sand, fluvioeolic sand, fluvial sand and loess. As a conclusion, radon is related to the sediment cycle in the study area. A geogenic radon risk map was created, which assists human health risk assessment and risk reduction since it indicates the potential of the source of indoor radon. The map shows that low and medium geogenic radon potential characterizes the study area in central Hungary. High risk occurs only locally. The results reveal that Quaternary sediments are inhomogeneous from a radon point of view, fluvial sediment has medium GRP, whereas the other rock formations such as drift sand, fluioeolic sand, fluvial sand and loess, found in the study area, have low GRP. - Highlights: • First geogenic radon potential map in Hungary. • Low and medium GRP characterizes the study area (Middle Hungary). • Mainly quaternary sediments characterizes the study area. • Radon is related to the erosion and deposition of the sediment cycle

Conduction velocity of action potentials measured from unidimensional latency-topography in human and frog skeletal muscle fibers.

Science.gov (United States)

Homma, S; Nakajima, Y; Hayashi, K; Toma, S

1986-01-01

Conduction of an action potential along skeletal muscle fibers was graphically displayed by unidimensional latency-topography, UDLT. Since the slopes of the equipotential line were linear and the width of the line was constant, it was possible to calculate conduction velocity from the slope. To determine conduction direction of the muscle action potential elicited by electric stimulation applied directly to the muscle, surface recording electrodes were placed on a two-dimensional plane over a human muscle. Thus a bi-dimensional topography was obtained. Then, twelve or sixteen surface electrodes were placed linearly along the longitudinal direction of the action potential conduction which was disclosed by the bi-dimensional topography. Thus conduction velocity of muscle action potential in man, calculated from the slope, was for m. brachioradialis, 3.9 +/- 0.4 m/s; for m. biceps brachii, 3.6 +/- 0.2 m/s; for m. sternocleidomastoideus, 3.6 +/- 0.4 m/s. By using a tungsten microelectrode to stimulate the motor axons, a convex-like equipotential line of an action potential in UDLT was obtained from human muscle fibers. Since a similar pattern of UDLT was obtained from experiments on isolated frog muscles, in which the muscle action potential was elicited by stimulating the motor axon, it was assumed that the maximum of the curve corresponds to the end-plate region, and that the slopes on both sides indicate bi-directional conduction of the action potential.

Fish oil curtails the human action potential dome in a heterogeneous manner: Implication for arrhythmogenesis

NARCIS (Netherlands)

Verkerk, Arie O.; den Ruijter, Hester M.; de Jonge, Nicolaas; Coronel, Ruben

2009-01-01

Omega-3 polyunsaturated fatty acids (omega3-PUFAs) from fish oil modulate various ion channels, including the L-type calcium current (I(Ca,L)). As a result, fish oil shortens the cardiac action potential and may cause a loss of the dome of the action potential (AP). Under conditions of increased

Impedance and electrically evoked compound action potential (ECAP drop within 24 hours after cochlear implantation.

Directory of Open Access Journals (Sweden)

Joshua Kuang-Chao Chen

Full Text Available Previous animal study revealed that post-implantation electrical detection levels significantly declined within days. The impact of cochlear implant (CI insertion on human auditory pathway in terms of impedance and electrically evoked compound action potential (ECAP variation within hours after surgery remains unclear, since at this time frequency mapping can only commence weeks after implantation due to factors associated with wound conditions. The study presented our experiences with regards to initial switch-on within 24 hours, and thus the findings about the milieus inside cochlea within the first few hours after cochlear implantation in terms of impedance/ECAP fluctuations. The charts of fifty-four subjects with profound hearing impairment were studied. A minimal invasive approach was used for cochlear implantation, characterized by a small skin incision (≈ 2.5 cm and soft techniques for cochleostomy. Impedance/ECAP was measured intro-operatively and within 24 hours post-operatively. Initial mapping within 24 hours post-operatively was performed in all patients without major complications. Impedance/ECAP became significantly lower measured within 24 hours post-operatively as compared with intra-operatively (p<0.001. There were no differences between pre-operative and post-operative threshold for air-conduction hearing. A significant drop of impedance/ECAP in one day after cochlear implantation was revealed for the first time in human beings. Mechanisms could be related to the restoration of neuronal sensitivity to the electrical stimulation, and/or the interaction between the matrix enveloping the electrodes and the electrical stimulation of the initial switch-on. Less wound pain/swelling and soft techniques both contributed to the success of immediate initial mapping, which implied a stable micro-environment inside the cochlea despite electrodes insertion. Our research invites further studies to correlate initial impedance/ECAP changes

Cardiac action potential repolarization revisited: early repolarization shows all-or-none behaviour.

Science.gov (United States)

Trenor, Beatriz; Cardona, Karen; Saiz, Javier; Noble, Denis; Giles, Wayne

2017-11-01

In healthy mammalian hearts the action potential (AP) waveform initiates and modulates each contraction, or heartbeat. As a result, AP height and duration are key physiological variables. In addition, rate-dependent changes in ventricular AP duration (APD), and variations in APD at a fixed heart rate are both reliable biomarkers of electrophysiological stability. Present guidelines for the likelihood that candidate drugs will increase arrhythmias rely on small changes in APD and Q-T intervals as criteria for safety pharmacology decisions. However, both of these measurements correspond to the final repolarization of the AP. Emerging clinical evidence draws attention to the early repolarization phase of the action potential (and the J-wave of the ECG) as an additional important biomarker for arrhythmogenesis. Here we provide a mechanistic background to this early repolarization syndrome by summarizing the evidence that both the initial depolarization and repolarization phases of the cardiac action potential can exhibit distinct time- and voltage-dependent thresholds, and also demonstrating that both can show regenerative all-or-none behaviour. An important consequence of this is that not all of the dynamics of action potential repolarization in human ventricle can be captured by data from single myocytes when these results are expressed as 'repolarization reserve'. For example, the complex pattern of cell-to-cell current flow that is responsible for AP conduction (propagation) within the mammalian myocardium can change APD and the Q-T interval of the electrocardiogram alter APD stability, and modulate responsiveness to pharmacological agents (such as Class III anti-arrhythmic drugs). © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

Differential effects of thioridazine enantiomers on action potential duration in rabbit papillary muscle

DEFF Research Database (Denmark)

Jensen, Ask Schou; Pennisi, Cristian Pablo; Sevcencu, Cristian

2015-01-01

with (+)-thioridazine. In this study we for the first time investigate the cardiotoxicity of the isolated thioridazine enantiomers and show their effects on ventricular repolarization. The effects of (+)-thioridazine, (-)-thioridazine, and racemate on the rabbit ventricular action potential duration (APD) were...... investigated in a randomized controlled blinded experiment. Action potentials were measured in papillary muscles isolated from 21 female rabbits, and the drug effect on 90% APD in comparison with control (DeltaDelta-APD90) was evaluated. Increasing concentrations of (+)-thioridazine and the racemate caused...

Multi-moment maps

DEFF Research Database (Denmark)

Swann, Andrew Francis; Madsen, Thomas Bruun

2012-01-01

We introduce a notion of moment map adapted to actions of Lie groups that preserve a closed three-form. We show existence of our multi-moment maps in many circumstances, including mild topological assumptions on the underlying manifold. Such maps are also shown to exist for all groups whose second...

Recovery of Action Potentials and Twitches after K-contractures in Frog Skeletal Muscle(Physiology)

OpenAIRE

Atsuko, Suzuki; Ibuki, Shirakawa; Kazunari, Noguchi; Hirohiko, Kishi; Haruo, Sugi; Department of Physiology, School of Medicine, Teikyo University:(Present office)Department of Physical Therapy, Health Science University; Department of Physiology, School of Medicine, Teikyo University; Department of Physiology, School of Medicine, Teikyo University; Department of Physiology, School of Medicine, Teikyo University; Department of Physiology, School of Medicine, Teikyo University

2004-01-01

To give information about intracellular Ca^ translocation during and after K-contractures in vertebrate skeletal muscle fibers, we examined recovery of action potentials and twitches after interruption and spontaneous relaxation of K-contractures at low temperature (3℃) that greatly reduced the rate of Ca^ reuptake by the sarcoplasmic reticulum. On membrane repolarization interrupting K-contractures, the amplitude of both action potentials and twitches recovered quickly, while the falling pha...

Conductance maps of quantum rings due to a local potential perturbation.

Science.gov (United States)

Petrović, M D; Peeters, F M; Chaves, A; Farias, G A

2013-12-11

We performed a numerical simulation of the dynamics of a Gaussian shaped wavepacket inside a small sized quantum ring, smoothly connected to two leads and exposed to a perturbing potential of a biased atomic force microscope tip. Using the Landauer formalism, we calculated conductance maps of this system in the case of single and two subband transport. We explain the main features in the conductance maps as due to the AFM tip influence on the wavepacket phase and amplitude. In the presence of an external magnetic field, the tip modifies the ϕ0 periodic Aharonov-Bohm oscillation pattern into a ϕ0/2 periodic Al'tshuler-Aronov-Spivak oscillation pattern. Our results in the case of multiband transport suggest tip selectivity to higher subbands, making them more observable in the total conductance map.

Brain-to-brain hyperclassification reveals action-specific motor mapping of observed actions in humans.

Science.gov (United States)

Smirnov, Dmitry; Lachat, Fanny; Peltola, Tomi; Lahnakoski, Juha M; Koistinen, Olli-Pekka; Glerean, Enrico; Vehtari, Aki; Hari, Riitta; Sams, Mikko; Nummenmaa, Lauri

2017-01-01

Seeing an action may activate the corresponding action motor code in the observer. It remains unresolved whether seeing and performing an action activates similar action-specific motor codes in the observer and the actor. We used novel hyperclassification approach to reveal shared brain activation signatures of action execution and observation in interacting human subjects. In the first experiment, two "actors" performed four types of hand actions while their haemodynamic brain activations were measured with 3-T functional magnetic resonance imaging (fMRI). The actions were videotaped and shown to 15 "observers" during a second fMRI experiment. Eleven observers saw the videos of one actor, and the remaining four observers saw the videos of the other actor. In a control fMRI experiment, one of the actors performed actions with closed eyes, and five new observers viewed these actions. Bayesian canonical correlation analysis was applied to functionally realign observers' and actors' fMRI data. Hyperclassification of the seen actions was performed with Bayesian logistic regression trained on actors' data and tested with observers' data. Without the functional realignment, between-subjects accuracy was at chance level. With the realignment, the accuracy increased on average by 15 percentage points, exceeding both the chance level and the accuracy without functional realignment. The highest accuracies were observed in occipital, parietal and premotor cortices. Hyperclassification exceeded chance level also when the actor did not see her own actions. We conclude that the functional brain activation signatures underlying action execution and observation are partly shared, yet these activation signatures may be anatomically misaligned across individuals.

Surface deformation during an action potential in pearled cells

Science.gov (United States)

Mussel, Matan; Fillafer, Christian; Ben-Porath, Gal; Schneider, Matthias F.

2017-11-01

Electric pulses in biological cells (action potentials) have been reported to be accompanied by a propagating cell-surface deformation with a nanoscale amplitude. Typically, this cell surface is covered by external layers of polymer material (extracellular matrix, cell wall material, etc.). It was recently demonstrated in excitable plant cells (Chara braunii) that the rigid external layer (cell wall) hinders the underlying deformation. When the cell membrane was separated from the cell wall by osmosis, a mechanical deformation, in the micrometer range, was observed upon excitation of the cell. The underlying mechanism of this mechanical pulse has, to date, remained elusive. Herein we report that Chara cells can undergo a pearling instability, and when the pearled fragments were excited even larger and more regular cell shape changes were observed (˜10 -100 μ m in amplitude). These transient cellular deformations were captured by a curvature model that is based on three parameters: surface tension, bending rigidity, and pressure difference across the surface. In this paper these parameters are extracted by curve-fitting to the experimental cellular shapes at rest and during excitation. This is a necessary step to identify the mechanical parameters that change during an action potential.

Onset Dynamics of Action Potentials in Rat Neocortical Neurons and Identified Snail Neurons: Quantification of the Difference

OpenAIRE

Volgushev, Maxim; Malyshev, Aleksey; Balaban, Pavel; Chistiakova, Marina; Volgushev, Stanislav; Wolf, Fred

2008-01-01

The generation of action potentials (APs) is a key process in the operation of nerve cells and the communication between neurons. Action potentials in mammalian central neurons are characterized by an exceptionally fast onset dynamics, which differs from the typically slow and gradual onset dynamics seen in identified snail neurons. Here we describe a novel method of analysis which provides a quantitative measure of the onset dynamics of action potentials. This method captures the...

Mapping ecosystem services potential in Lithuania

Science.gov (United States)

Depellegrin, Daniel; Misiune, Ieva; Pereira, Paulo

2016-04-01

Ecosystem services (ES) are understood as the benefits that humans get from ecosystems functions. They are divided in providing, regulating, supporting and cultural. The correct management of ES is fundamental to achieve sustainable development goals. A good assessment of ES potential can be obtained using GIS techniques, in order to have a spatial dimension of ES distribution. This will help to have a better territorial planning, improve ES capacity, and have more benefits. ES potential analysis can be carried out based on the ES matrix developed by Burkhard et al. (2009). This method is based on the attribution a rank from 0 to 5 (0= no capacity to 5=very high relevant capacity) to the land use classes of the corine land cover (CLC). This represents an important advantage since a determined land use can be related with a certain number of services. The objective of this work is to Map the ES potential in Lithuania. The results showed that Lithuania has a high potential for regulating services, followed by cultural and provisioning services. Urban areas provide a very small amount of services, contrary to forest, where the highest potential is observed. The most comon land covers in Lithuania are non-irrigated arable land, complex cultivation patterns, mixed and coniferous forest. Total and regulating and cultural ES had dispersed pattern showing that they are scattered in the territory. They are located mainly in forested and coastal areas. In relation to provisioning services they had a clustered distribution, and they were mainly observed in the central part of Lithuania. References Burkhard B, Kroll F, Müller F, Windhorst W. 2009. Landscapes' capacities to provide ecosystem services - a concept for land-cover based assessments. Landsc. Online. 15:1-22

Motor mapping of implied actions during perception of emotional body language.

Science.gov (United States)

Borgomaneri, Sara; Gazzola, Valeria; Avenanti, Alessio

2012-04-01

Perceiving and understanding emotional cues is critical for survival. Using the International Affective Picture System (IAPS) previous TMS studies have found that watching humans in emotional pictures increases motor excitability relative to seeing landscapes or household objects, suggesting that emotional cues may prime the body for action. Here we tested whether motor facilitation to emotional pictures may reflect the simulation of the human motor behavior implied in the pictures occurring independently of its emotional valence. Motor-evoked potentials (MEPs) to single-pulse TMS of the left motor cortex were recorded from hand muscles during observation and categorization of emotional and neutral pictures. In experiment 1 participants watched neutral, positive and negative IAPS stimuli, while in experiment 2, they watched pictures depicting human emotional (joyful, fearful), neutral body movements and neutral static postures. Experiment 1 confirms the increase in excitability for emotional IAPS stimuli found in previous research and shows, however, that more implied motion is perceived in emotional relative to neutral scenes. Experiment 2 shows that motor excitability and implied motion scores for emotional and neutral body actions were comparable and greater than for static body postures. In keeping with embodied simulation theories, motor response to emotional pictures may reflect the simulation of the action implied in the emotional scenes. Action simulation may occur independently of whether the observed implied action carries emotional or neutral meanings. Our study suggests the need of controlling implied motion when exploring motor response to emotional pictures of humans. Copyright © 2012 Elsevier Inc. All rights reserved.

Scaling of the quark-antiquark potential and improved actions in SU(2) lattice gauge theory

International Nuclear Information System (INIS)

Montvay, I.; Gutbrod, F.

1983-11-01

The scaling behaviour of the quark-antiquark potential is investigated by a high statistics Monte Carlo calculation in SU(2) lattice gauge theory. Besides the standard one-plaquette action we also use Symanzik's tree-level improved action and Wilson's block-spin improved action. No significant differences between Symanzik's action and the standard action have been observed. For small β Wilson's action scales differently. The string tension value chi extracted from the data corresponds to Λsub(latt) = (0.018 +- 0.001) √chi for the one-plaquette action. (orig.)

Massive calculations of electrostatic potentials and structure maps of biopolymers in a distributed computing environment

International Nuclear Information System (INIS)

Akishina, T.P.; Ivanov, V.V.; Stepanenko, V.A.

2013-01-01

Among the key factors determining the processes of transcription and translation are the distributions of the electrostatic potentials of DNA, RNA and proteins. Calculations of electrostatic distributions and structure maps of biopolymers on computers are time consuming and require large computational resources. We developed the procedures for organization of massive calculations of electrostatic potentials and structure maps for biopolymers in a distributed computing environment (several thousands of cores).

Spatial data analysis and integration for regional-scale geothermal potential mapping, West Java, Indonesia

Energy Technology Data Exchange (ETDEWEB)

Carranza, Emmanuel John M.; Barritt, Sally D. [Department of Earth Systems Analysis, International Institute for Geo-information Science and Earth Observation (ITC), Enschede (Netherlands); Wibowo, Hendro; Sumintadireja, Prihadi [Laboratory of Volcanology and Geothermal, Geology Department, Institute of Technology Bandung (ITB), Bandung (Indonesia)

2008-06-15

Conceptual modeling and predictive mapping of potential for geothermal resources at the regional-scale in West Java are supported by analysis of the spatial distribution of geothermal prospects and thermal springs, and their spatial associations with geologic features derived from publicly available regional-scale spatial data sets. Fry analysis shows that geothermal occurrences have regional-scale spatial distributions that are related to Quaternary volcanic centers and shallow earthquake epicenters. Spatial frequency distribution analysis shows that geothermal occurrences have strong positive spatial associations with Quaternary volcanic centers, Quaternary volcanic rocks, quasi-gravity lows, and NE-, NNW-, WNW-trending faults. These geological features, with their strong positive spatial associations with geothermal occurrences, constitute spatial recognition criteria of regional-scale geothermal potential in a study area. Application of data-driven evidential belief functions in GIS-based predictive mapping of regional-scale geothermal potential resulted in delineation of high potential zones occupying 25% of West Java, which is a substantial reduction of the search area for further exploration of geothermal resources. The predicted high potential zones delineate about 53-58% of the training geothermal areas and 94% of the validated geothermal occurrences. The results of this study demonstrate the value of regional-scale geothermal potential mapping in: (a) data-poor situations, such as West Java, and (b) regions with geotectonic environments similar to the study area. (author)

Urocortin2 prolongs action potential duration and modulates potassium currents in guinea pig myocytes and HEK293 cells.

Science.gov (United States)

Yang, Li-Zhen; Zhu, Yi-Chun

2015-07-05

We previously reported that activation of corticotropin releasing factor receptor type 2 by urocortin2 up-regulates both L-type Ca(2+) channels and intracellular Ca(2+) concentration in ventricular myocytes and plays an important role in cardiac contractility and arrhythmogenesis. This study goal was to further test the hypothesis that urocortin2 may modulate action potentials as well as rapidly and slowly activating delayed rectifier potassium currents. With whole cell patch-clamp techniques, action potentials and slowly activating delayed rectifier potassium currents were recorded in isolated guinea pig ventricular myocytes, respectively. And rapidly activating delayed rectifier potassium currents were tested in hERG-HEK293 cells. Urocortin2 produced a time- and concentration-dependent prolongation of action potential duration. The EC50 values of action potential duration and action potential duration at 90% of repolarization were 14.73 and 24.3nM respectively. The prolongation of action potential duration of urocortin2 was almost completely or partly abolished by H-89 (protein kinase A inhibitor) or KB-R7943 (Na(+)/Ca(2+) exchange inhibitor) pretreatment respectively. And urocortin2 caused reduction of rapidly activating delayed rectifier potassium currents in hERG-HEK293 cells. In addition, urocortin2 slowed the rate of slowly activating delayed rectifier potassium channel activation, and rightward shifted the threshold of slowly activating delayed rectifier potassium currents to more positive potentials. Urocortin2 prolonged action potential duration via activation of protein kinase A and Na(+)/ Ca(2+) exchange in isolated guinea pig ventricular myocytes in a time- and concentration- dependent manner. In hERG-HEK293 cells, urocortin2 reduced rapidly activating delayed rectifier potassium current density which may contribute to action potential duration prolongation. Copyright © 2015 Elsevier B.V. All rights reserved.

A Framework for Mining Actionable Navigation Patterns from In-Store RFID Datasets via Indoor Mapping

Science.gov (United States)

Shen, Bin; Zheng, Qiuhua; Li, Xingsen; Xu, Libo

2015-01-01

With the quick development of RFID technology and the decreasing prices of RFID devices, RFID is becoming widely used in various intelligent services. Especially in the retail application domain, RFID is increasingly adopted to capture the shopping tracks and behavior of in-store customers. To further enhance the potential of this promising application, in this paper, we propose a unified framework for RFID-based path analytics, which uses both in-store shopping paths and RFID-based purchasing data to mine actionable navigation patterns. Four modules of this framework are discussed, which are: (1) mapping from the physical space to the cyber space, (2) data preprocessing, (3) pattern mining and (4) knowledge understanding and utilization. In the data preprocessing module, the critical problem of how to capture the mainstream shopping path sequences while wiping out unnecessary redundant and repeated details is addressed in detail. To solve this problem, two types of redundant patterns, i.e., loop repeat pattern and palindrome-contained pattern are recognized and the corresponding processing algorithms are proposed. The experimental results show that the redundant pattern filtering functions are effective and scalable. Overall, this work builds a bridge between indoor positioning and advanced data mining technologies, and provides a feasible way to study customers’ shopping behaviors via multi-source RFID data. PMID:25751076

Electrostatic potential map modelling with COSY Infinity

International Nuclear Information System (INIS)

Maloney, J.A.; Baartman, R.; Planche, T.; Saminathan, S.

2016-01-01

COSY Infinity (Makino and Berz, 2005) is a differential-algebra based simulation code which allows accurate calculation of transfer maps to arbitrary order. COSY’s existing internal procedures were modified to allow electrostatic elements to be specified using an array of field potential data from the midplane. Additionally, a new procedure was created allowing electrostatic elements and their fringe fields to be specified by an analytic function. This allows greater flexibility in accurately modelling electrostatic elements and their fringe fields. Applied examples of these new procedures are presented including the modelling of a shunted electrostatic multipole designed with OPERA, a spherical electrostatic bender, and the effects of different shaped apertures in an electrostatic beam line.

Data-driven mapping of the potential mountain permafrost distribution.

Science.gov (United States)

Deluigi, Nicola; Lambiel, Christophe; Kanevski, Mikhail

2017-07-15

Existing mountain permafrost distribution models generally offer a good overview of the potential extent of this phenomenon at a regional scale. They are however not always able to reproduce the high spatial discontinuity of permafrost at the micro-scale (scale of a specific landform; ten to several hundreds of meters). To overcome this lack, we tested an alternative modelling approach using three classification algorithms belonging to statistics and machine learning: Logistic regression, Support Vector Machines and Random forests. These supervised learning techniques infer a classification function from labelled training data (pixels of permafrost absence and presence) with the aim of predicting the permafrost occurrence where it is unknown. The research was carried out in a 588km 2 area of the Western Swiss Alps. Permafrost evidences were mapped from ortho-image interpretation (rock glacier inventorying) and field data (mainly geoelectrical and thermal data). The relationship between selected permafrost evidences and permafrost controlling factors was computed with the mentioned techniques. Classification performances, assessed with AUROC, range between 0.81 for Logistic regression, 0.85 with Support Vector Machines and 0.88 with Random forests. The adopted machine learning algorithms have demonstrated to be efficient for permafrost distribution modelling thanks to consistent results compared to the field reality. The high resolution of the input dataset (10m) allows elaborating maps at the micro-scale with a modelled permafrost spatial distribution less optimistic than classic spatial models. Moreover, the probability output of adopted algorithms offers a more precise overview of the potential distribution of mountain permafrost than proposing simple indexes of the permafrost favorability. These encouraging results also open the way to new possibilities of permafrost data analysis and mapping. Copyright © 2017 Elsevier B.V. All rights reserved.

The different intracellular action potentials of fast and slow muscle fibres = Différences entre les potentiels d'action intracellulaires de fibres musculaires rapides et lentes

NARCIS (Netherlands)

Wallinga, W.; Gielen, Frans L.H.; Wirtz, Peter; de Jong, Paul; Broenink, Johannes F.

1985-01-01

The time course of the intracellular action potential was studied quantitatively, because it is an important factor in the generation of electromyographic signals. In in vivo preparations of the m. EDL and m. soleus of the rat single motor units were stimulated and intracellular action potentials

The Potential of Deweyan-Inspired Action Research

Science.gov (United States)

Stark, Jody L.

2014-01-01

In its broadest sense, pragmatism could be said to be the philosophical orientation of all action research. Action research is characterized by research, action, and participation grounded in democratic principles and guided by the aim of social improvement. Furthermore, action research is an active process of inquiry that does not admit…

Inhibition by TRPA1 agonists of compound action potentials in the frog sciatic nerve

Energy Technology Data Exchange (ETDEWEB)

Matsushita, Akitomo; Ohtsubo, Sena; Fujita, Tsugumi; Kumamoto, Eiichi, E-mail: kumamote@cc.saga-u.ac.jp

2013-04-26

Highlights: •TRPA1 agonists inhibited compound action potentials in frog sciatic nerves. •This inhibition was not mediated by TRPA1 channels. •This efficacy was comparable to those of lidocaine and cocaine. •We found for the first time an ability of TRPA1 agonists to inhibit nerve conduction. -- Abstract: Although TRPV1 and TRPM8 agonists (vanilloid capsaicin and menthol, respectively) at high concentrations inhibit action potential conduction, it remains to be unknown whether TRPA1 agonists have a similar action. The present study examined the actions of TRPA1 agonists, cinnamaldehyde (CA) and allyl isothiocyanate (AITC), which differ in chemical structure from each other, on compound action potentials (CAPs) recorded from the frog sciatic nerve by using the air-gap method. CA and AITC concentration-dependently reduced the peak amplitude of the CAP with the IC{sub 50} values of 1.2 and 1.5 mM, respectively; these activities were resistant to a non-selective TRP antagonist ruthenium red or a selective TRPA1 antagonist HC-030031. The CA and AITC actions were distinct in property; the latter but not former action was delayed in onset and partially reversible, and CA but not AITC increased thresholds to elicit CAPs. A CAP inhibition was seen by hydroxy-α-sanshool (by 60% at 0.05 mM), which activates both TRPA1 and TRPV1 channels, a non-vanilloid TRPV1 agonist piperine (by 20% at 0.07 mM) and tetrahydrolavandulol (where the six-membered ring of menthol is opened; IC{sub 50} = 0.38 mM). It is suggested that TRPA1 agonists as well as TRPV1 and TRPM8 agonists have an ability to inhibit nerve conduction without TRP activation, although their agonists are quite different in chemical structure from each other.

Coastal Hazards Maps: Actionable Information for Communities Facing Sea-Level Rise (Invited)

Science.gov (United States)

Gibeaut, J. C.; Barraza, E.

2010-12-01

Barrier islands along the U.S. Gulf coast remain under increasing pressure from development. This development and redevelopment is occurring despite recent hurricanes, ongoing erosion, and sea-level rise. To lessen the impacts of these hazards, local governments need information in a form that is useful for informing the public, making policy, and enforcing development rules. We recently completed the Galveston Island Geohazards Map for the city of Galveston, Texas and are currently developing maps for the Mustang and South Padre Island communities. The maps show areas that vary in their susceptibility to, and function for, mitigating the effects of geological processes, including sea-level rise, land subsidence, erosion and storm-surge flooding and washover. The current wetlands, beaches and dunes are mapped as having the highest geohazard potential both in terms of their exposure to hazardous conditions and their mitigating effects of those hazards for the rest of the island. These existing “critical environments” are generally protected under existing regulations. Importantly, however, the mapping recognizes that sea-level rise and shoreline retreat are changing the island; therefore, 60-year model projections of the effects of these changes are incorporated into the map. The areas that we project will become wetlands, beaches and dunes in the next 60 years are not protected. These areas are the most difficult to deal with from a policy point of view, yet we must address what happens there if real progress is to be made in how we live with sea-level rise. The geohazards maps draw on decades of geological knowledge of how barrier islands behave and put it in a form that is intuitive to the public and directly useful to planners. Some of the “messages” in the map include: leave salt marshes alone and give them room to migrate inland as sea level rises; set back and move development away from the shoreline to provide space for beaches and protective dunes

Role of action potential configuration and the contribution of Ca2+ and K+ currents to isoprenaline-induced changes in canine ventricular cells

Science.gov (United States)

Szentandrássy, N; Farkas, V; Bárándi, L; Hegyi, B; Ruzsnavszky, F; Horváth, B; Bányász, T; Magyar, J; Márton, I; Nánási, PP

2012-01-01

BACKGROUND AND PURPOSE Although isoprenaline (ISO) is known to activate several ion currents in mammalian myocardium, little is known about the role of action potential morphology in the ISO-induced changes in ion currents. Therefore, the effects of ISO on action potential configuration, L-type Ca2+ current (ICa), slow delayed rectifier K+ current (IKs) and fast delayed rectifier K+ current (IKr) were studied and compared in a frequency-dependent manner using canine isolated ventricular myocytes from various transmural locations. EXPERIMENTAL APPROACH Action potentials were recorded with conventional sharp microelectrodes; ion currents were measured using conventional and action potential voltage clamp techniques. KEY RESULTS In myocytes displaying a spike-and-dome action potential configuration (epicardial and midmyocardial cells), ISO caused reversible shortening of action potentials accompanied by elevation of the plateau. ISO-induced action potential shortening was absent in endocardial cells and in myocytes pretreated with 4-aminopyridine. Application of the IKr blocker E-4031 failed to modify the ISO effect, while action potentials were lengthened by ISO in the presence of the IKs blocker HMR-1556. Both action potential shortening and elevation of the plateau were prevented by pretreatment with the ICa blocker nisoldipine. Action potential voltage clamp experiments revealed a prominent slowly inactivating ICa followed by a rise in IKs, both currents increased with increasing the cycle length. CONCLUSIONS AND IMPLICATIONS The effect of ISO in canine ventricular cells depends critically on action potential configuration, and the ISO-induced activation of IKs– but not IKr– may be responsible for the observed shortening of action potentials. PMID:22563726

Mapping the lattice-vibration potential using terahertz pulses

Science.gov (United States)

Korpa, C. L.; Tóth, Gy; Hebling, J.

2018-02-01

We develop a method for mapping the anharmonic lattice potential using the time-dependent electric field of the transmitted pulse through thin sample supported by a substrate of non-negligible thickness. Assuming linear propagation in the substrate we fully take into account internal reflection in it while the sample can show arbitrary nonlinear response. We examine the effect of frequency averaging appropriate for broad-band pulse and compare the results taking into account the full frequency dependence. We illustrate the procedure applying it to a model based on recently observed ferroelectric soft mode nonlinearity in SrTiO3.

Incorporated fish oil fatty acids prevent action potential shortening induced by circulating fish oil fatty acids

Directory of Open Access Journals (Sweden)

Hester M Den Ruijter

2010-11-01

Full Text Available Increased consumption of fatty fish, rich in omega-3 polyunsaturated fatty acids (3-PUFAs reduces the severity and number of arrhythmias. Long term 3-PUFA-intake modulates the activity of several cardiac ion channels leading to cardiac action potential shortening. Circulating 3-PUFAs in the bloodstream and incorporated 3-PUFAs in the cardiac membrane have a different mechanism to shorten the action potential. It is, however, unknown whether circulating 3-PUFAs in the bloodstream enhance or diminish the effects of incorporated 3-PUFAs. In the present study, we address this issue. Rabbits were fed a diet rich in fish oil (3 or sunflower oil (9, as control for 3 weeks. Ventricular myocytes were isolated by enzymatic dissociation and action potentials were measured using the perforated patch clamp technique in the absence and presence of acutely administered 3-PUFAs. Plasma of 3 fed rabbits contained more free eicosapentaenoic acid (EPA and isolated myocytes of 3 fed rabbits contained higher amounts of both EPA and docosahexaenoic acid (DHA in their sarcolemma compared to control. In the absence of acutely administered fatty acids, 3 myocytes had a shorter action potential with a more negative plateau than 9 myocytes. In the 9 myocytes, but not in the 3 myocytes, acute administration of a mixture of EPA+DHA shortened the action potential significantly. From these data we conclude that incorporated 3-PUFAs into the sarcolemma and acutely administered 3 fatty acids do not have a cumulative effect on action potential duration and morphology. As a consequence, patients with a high cardiac 3-PUFA status will probably not benefit from short term 3 supplementation as an antiarrhythmic therapy.

ER Stress-Mediated Signaling: Action Potential and Ca(2+) as Key Players.

Science.gov (United States)

Bahar, Entaz; Kim, Hyongsuk; Yoon, Hyonok

2016-09-15

The proper functioning of the endoplasmic reticulum (ER) is crucial for multiple cellular activities and survival. Disturbances in the normal ER functions lead to the accumulation and aggregation of unfolded proteins, which initiates an adaptive response, the unfolded protein response (UPR), in order to regain normal ER functions. Failure to activate the adaptive response initiates the process of programmed cell death or apoptosis. Apoptosis plays an important role in cell elimination, which is essential for embryogenesis, development, and tissue homeostasis. Impaired apoptosis can lead to the development of various pathological conditions, such as neurodegenerative and autoimmune diseases, cancer, or acquired immune deficiency syndrome (AIDS). Calcium (Ca(2+)) is one of the key regulators of cell survival and it can induce ER stress-mediated apoptosis in response to various conditions. Ca(2+) regulates cell death both at the early and late stages of apoptosis. Severe Ca(2+) dysregulation can promote cell death through apoptosis. Action potential, an electrical signal transmitted along the neurons and muscle fibers, is important for conveying information to, from, and within the brain. Upon the initiation of the action potential, increased levels of cytosolic Ca(2+) (depolarization) lead to the activation of the ER stress response involved in the initiation of apoptosis. In this review, we discuss the involvement of Ca(2+) and action potential in ER stress-mediated apoptosis.

Antibacterial free fatty acids: activities, mechanisms of action and biotechnological potential.

Science.gov (United States)

Desbois, Andrew P; Smith, Valerie J

2010-02-01

Amongst the diverse and potent biological activities of free fatty acids (FFAs) is the ability to kill or inhibit the growth of bacteria. The antibacterial properties of FFAs are used by many organisms to defend against parasitic or pathogenic bacteria. Whilst their antibacterial mode of action is still poorly understood, the prime target of FFA action is the cell membrane, where FFAs disrupt the electron transport chain and oxidative phosphorylation. Besides interfering with cellular energy production, FFA action may also result from the inhibition of enzyme activity, impairment of nutrient uptake, generation of peroxidation and auto-oxidation degradation products or direct lysis of bacterial cells. Their broad spectrum of activity, non-specific mode of action and safety makes them attractive as antibacterial agents for various applications in medicine, agriculture and food preservation, especially where the use of conventional antibiotics is undesirable or prohibited. Moreover, the evolution of inducible FFA-resistant phenotypes is less problematic than with conventional antibiotics. The potential for commercial or biomedical exploitation of antibacterial FFAs, especially for those from natural sources, is discussed.

Potential and limitations of using soil mapping information to understand landscape hydrology

Directory of Open Access Journals (Sweden)

F. Terribile

2011-12-01

Full Text Available This paper addresses the following points: how can whole soil data from normally available soil mapping databases (both conventional and those integrated by digital soil mapping procedures be usefully employed in hydrology? Answering this question requires a detailed knowledge of the quality and quantity of information embedded in and behind a soil map.

To this end a description of the process of drafting soil maps was prepared (which is included in Appendix A of this paper. Then a detailed screening of content and availability of soil maps and database was performed, with the objective of an analytical evaluation of the potential and the limitations of soil data obtained through soil surveys and soil mapping. Then we reclassified the soil features according to their direct, indirect or low hydrologic relevance. During this phase, we also included information regarding whether this data was obtained by qualitative, semi-quantitative or quantitative methods. The analysis was performed according to two main points of concern: (i the hydrological interpretation of the soil data and (ii the quality of the estimate or measurement of the soil feature.

The interaction between pedology and hydrology processes representation was developed through the following Italian case studies with different hydropedological inputs: (i comparative land evaluation models, by means of an exhaustive itinerary from simple to complex modelling applications depending on soil data availability, (ii mapping of soil hydrological behaviour for irrigation management at the district scale, where the main hydropedological input was the application of calibrated pedo-transfer functions and the Hydrological Function Unit concept, and (iii flood event simulation in an ungauged basin, with the functional aggregation of different soil units for a simplified soil pattern.

In conclusion, we show that special care is required in handling data from soil

Revisiting Renewable Energy Map in Indonesia: Seasonal Hydro and Solar Energy Potential for Rural Off-Grid Electrification (Provincial Level

Directory of Open Access Journals (Sweden)

Agung Wahyuono Ruri

2018-01-01

Full Text Available Regarding the acceleration of renewable energy diffusion in Indonesia as well as achieving the national energy mix target, renewable energy map is essential to provide useful information to build renewable energy system. This work aims at updating the renewable energy potential map, i.e. hydro and solar energy potential, with a revised model based on the global climate data. The renewable energy map is intended to assist the design off-grid system by hydropower plant or photovoltaic system, particularly for rural electrification. Specifically, the hydro energy map enables the stakeholders to determine the suitable on-site hydro energy technology (from pico-hydro, micro-hydro, mini-hydro to large hydropower plant. Meanwhile, the solar energy map depicts not only seasonal solar energy potential but also estimated energy output from photovoltaic system.

Amphetamine elevates nucleus accumbens dopamine via an action potential-dependent mechanism that is modulated by endocannabinoids

Science.gov (United States)

Covey, Dan P.; Bunner, Kendra D.; Schuweiler, Douglas R.; Cheer, Joseph F.; Garris, Paul A.

2018-01-01

The reinforcing effects of abused drugs are mediated by their ability to elevate nucleus accumbens dopamine. Amphetamine (AMPH) was historically thought to increase dopamine by an action potential-independent, non-exocytotic type of release called efflux, involving reversal of dopamine transporter function and driven by vesicular dopamine depletion. Growing evidence suggests that AMPH also acts by an action potential-dependent mechanism. Indeed, fast-scan cyclic voltammetry demonstrates that AMPH activates dopamine transients, reward-related phasic signals generated by burst firing of dopamine neurons and dependent on intact vesicular dopamine. Not established for AMPH but indicating a shared mechanism, endocannabinoids facilitate this activation of dopamine transients by broad classes of abused drugs. Here, using fast-scan cyclic voltammetry coupled to pharmacological manipulations in awake rats, we investigated the action potential and endocannabinoid dependence of AMPH-induced elevations in nucleus accumbens dopamine. AMPH increased the frequency, amplitude and duration of transients, which were observed riding on top of slower dopamine increases. Surprisingly, silencing dopamine neuron firing abolished all AMPH-induced dopamine elevations, identifying an action potential-dependent origin. Blocking cannabinoid type 1 receptors prevented AMPH from increasing transient frequency, similar to reported effects on other abused drugs, but not from increasing transient duration and inhibiting dopamine uptake. Thus, AMPH elevates nucleus accumbens dopamine by eliciting transients via cannabinoid type 1 receptors and promoting the summation of temporally coincident transients, made more numerous, larger and wider by AMPH. Collectively, these findings are inconsistent with AMPH eliciting action potential-independent dopamine efflux and vesicular dopamine depletion, and support endocannabinoids facilitating phasic dopamine signalling as a common action in drug reinforcement

Amphetamine elevates nucleus accumbens dopamine via an action potential-dependent mechanism that is modulated by endocannabinoids.

Science.gov (United States)

Covey, Dan P; Bunner, Kendra D; Schuweiler, Douglas R; Cheer, Joseph F; Garris, Paul A

2016-06-01

The reinforcing effects of abused drugs are mediated by their ability to elevate nucleus accumbens dopamine. Amphetamine (AMPH) was historically thought to increase dopamine by an action potential-independent, non-exocytotic type of release called efflux, involving reversal of dopamine transporter function and driven by vesicular dopamine depletion. Growing evidence suggests that AMPH also acts by an action potential-dependent mechanism. Indeed, fast-scan cyclic voltammetry demonstrates that AMPH activates dopamine transients, reward-related phasic signals generated by burst firing of dopamine neurons and dependent on intact vesicular dopamine. Not established for AMPH but indicating a shared mechanism, endocannabinoids facilitate this activation of dopamine transients by broad classes of abused drugs. Here, using fast-scan cyclic voltammetry coupled to pharmacological manipulations in awake rats, we investigated the action potential and endocannabinoid dependence of AMPH-induced elevations in nucleus accumbens dopamine. AMPH increased the frequency, amplitude and duration of transients, which were observed riding on top of slower dopamine increases. Surprisingly, silencing dopamine neuron firing abolished all AMPH-induced dopamine elevations, identifying an action potential-dependent origin. Blocking cannabinoid type 1 receptors prevented AMPH from increasing transient frequency, similar to reported effects on other abused drugs, but not from increasing transient duration and inhibiting dopamine uptake. Thus, AMPH elevates nucleus accumbens dopamine by eliciting transients via cannabinoid type 1 receptors and promoting the summation of temporally coincident transients, made more numerous, larger and wider by AMPH. Collectively, these findings are inconsistent with AMPH eliciting action potential-independent dopamine efflux and vesicular dopamine depletion, and support endocannabinoids facilitating phasic dopamine signalling as a common action in drug reinforcement

Fokker-action principle for a system of particles interacting through a linear potential

International Nuclear Information System (INIS)

Rivacoba, A.

1984-01-01

A Fokker-action principle for a system of scalar particles interacting through their time-symmetric relativistic generalization of linear potential is obtained. From this action, motion equations and conservation laws for the total energy and angular momentum of the system, in which field contributions are included, are derived. These equations are exactly applied to the problem suggested by Schild of two particles moving in circular concentric orbits

Axon initial segment Kv1 channels control axonal action potential waveform and synaptic efficacy

NARCIS (Netherlands)

Kole, Maarten H. P.; Letzkus, Johannes J.; Stuart, Greg J.

2007-01-01

Action potentials are binary signals that transmit information via their rate and temporal pattern. In this context, the axon is thought of as a transmission line, devoid of a role in neuronal computation. Here, we show a highly localized role of axonal Kv1 potassium channels in shaping the action

Application of Emergency Action Levels from Potential Release at Research Reactor HANARO

International Nuclear Information System (INIS)

Kim, Jongsoo; Lee, Goan Yub; Lee, Hae Choi; Kim, Bong Suk

2014-01-01

Execution of the protective action promptly is possible that Emergency Action Levels (EALs) must be established for a radiological release from nuclear facility. The EALs for electric power reactor are already developed and applied to recognize an emergency situation rapidly. Recently the IAEA published the safety report including the EALs for research reactor. This paper describes the EALs to apply for a potential release pathway at the research reactor HANARO. The results of table 1 and 2 will be higher than actual because the weather condition in real situation is difference. However, the EALs applying the potential stack release, ground release and site can be useful for research reactor HANARO making the emergency declaration. The EALs at the site boundary of the table 3 can be applied to protect the off-site public

Dynamic Action Potential Restitution Contributes to Mechanical Restitution in Right Ventricular Myocytes From Pulmonary Hypertensive Rats.

Science.gov (United States)

Hardy, Matthew E L; Pervolaraki, Eleftheria; Bernus, Olivier; White, Ed

2018-01-01

We investigated the steepened dynamic action potential duration (APD) restitution of rats with pulmonary artery hypertension (PAH) and right ventricular (RV) failure and tested whether the observed APD restitution properties were responsible for negative mechanical restitution in these myocytes. PAH and RV failure were provoked in male Wistar rats by a single injection of monocrotaline (MCT) and compared with saline-injected animals (CON). Action potentials were recorded from isolated RV myocytes at stimulation frequencies between 1 and 9 Hz. Action potential waveforms recorded at 1 Hz were used as voltage clamp profiles (action potential clamp) at stimulation frequencies between 1 and 7 Hz to evoke rate-dependent currents. Voltage clamp profiles mimicking typical CON and MCT APD restitution were applied and cell shortening simultaneously monitored. Compared with CON myocytes, MCT myocytes were hypertrophied; had less polarized diastolic membrane potentials; had action potentials that were triggered by decreased positive current density and shortened by decreased negative current density; APD was longer and APD restitution steeper. APD90 restitution was unchanged by exposure to the late Na + -channel blocker (5 μM) ranolazine or the intracellular Ca 2+ buffer BAPTA. Under AP clamp, stimulation frequency-dependent inward currents were smaller in MCT myocytes and were abolished by BAPTA. In MCT myocytes, increasing stimulation frequency decreased contraction amplitude when depolarization duration was shortened, to mimic APD restitution, but not when depolarization duration was maintained. We present new evidence that the membrane potential of PAH myocytes is less stable than normal myocytes, being more easily perturbed by external currents. These observations can explain increased susceptibility to arrhythmias. We also present novel evidence that negative APD restitution is at least in part responsible for the negative mechanical restitution in PAH myocytes. Thus

Sensitivity to structure in action sequences: An infant event-related potential study.

Science.gov (United States)

Monroy, Claire D; Gerson, Sarah A; Domínguez-Martínez, Estefanía; Kaduk, Katharina; Hunnius, Sabine; Reid, Vincent

2017-05-06

Infants are sensitive to structure and patterns within continuous streams of sensory input. This sensitivity relies on statistical learning, the ability to detect predictable regularities in spatial and temporal sequences. Recent evidence has shown that infants can detect statistical regularities in action sequences they observe, but little is known about the neural process that give rise to this ability. In the current experiment, we combined electroencephalography (EEG) with eye-tracking to identify electrophysiological markers that indicate whether 8-11-month-old infants detect violations to learned regularities in action sequences, and to relate these markers to behavioral measures of anticipation during learning. In a learning phase, infants observed an actor performing a sequence featuring two deterministic pairs embedded within an otherwise random sequence. Thus, the first action of each pair was predictive of what would occur next. One of the pairs caused an action-effect, whereas the second did not. In a subsequent test phase, infants observed another sequence that included deviant pairs, violating the previously observed action pairs. Event-related potential (ERP) responses were analyzed and compared between the deviant and the original action pairs. Findings reveal that infants demonstrated a greater Negative central (Nc) ERP response to the deviant actions for the pair that caused the action-effect, which was consistent with their visual anticipations during the learning phase. Findings are discussed in terms of the neural and behavioral processes underlying perception and learning of structured action sequences. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mitigation Action Plan

Energy Technology Data Exchange (ETDEWEB)

1994-02-01

This Mitigation Action Plan (MAP) focuses on mitigation commitments stated in the Supplemental Environmental Impact Statement (SEIS) and the Record of Decision (ROD) for the Naval Petroleum Reserve No. 1 (NPR-1). Specific commitments and mitigation implementation actions are listed in Appendix A-Mitigation Actions, and form the central focus of this MAP. They will be updated as needed to allow for organizational, regulatory, or policy changes. It is the intent of DOE to comply with all applicable federal, state, and local environmental, safety, and health laws and regulations. Eighty-six specific commitments were identified in the SEIS and associated ROD which pertain to continued operation of NPR-1 with petroleum production at the Maximum Efficient Rate (MER). The mitigation measures proposed are expected to reduce impacts as much as feasible, however, as experience is gained in actual implementation of these measures, some changes may be warranted.

Mapping Soil Erosion Factors and Potential Erosion Risk for the National Park "Central Balkan"

Science.gov (United States)

Ilieva, Diliana; Malinov, Ilia

2014-05-01

Soil erosion is widely recognised environmental problem. The report aims at presenting the main results from assessment and mapping of the factors of sheet water erosion and the potential erosion risk on the territory of National Park "Central Balkan". For this purpose, the Universal Soil Loss Equation (USLE) was used for predicting soil loss from erosion. The influence of topography (LS-factor) and soil erodibility (K-factor) was assessed using small-scale topographic and soil maps. Rainfall erosivity (R-factor) was calculated from data of rainfalls with amounts exceeding 9.5 mm from 14 hydro-meteorological stations. The values of the erosion factors (R, K and LS) were presented for the areas of forest, sub-alpine and alpine zones. Using the methods of GIS, maps were plotted presenting the area distribution among the classes of the soil erosion factors and the potential risk in the respective zones. The results can be used for making accurate decisions for soil conservation and sustainable land management in the park.

A Framework for Mining Actionable Navigation Patterns from In-Store RFID Datasets via Indoor Mapping

Directory of Open Access Journals (Sweden)

Bin Shen

2015-03-01

Full Text Available With the quick development of RFID technology and the decreasing prices of RFID devices, RFID is becoming widely used in various intelligent services. Especially in the retail application domain, RFID is increasingly adopted to capture the shopping tracks and behavior of in-store customers. To further enhance the potential of this promising application, in this paper, we propose a unified framework for RFID-based path analytics, which uses both in-store shopping paths and RFID-based purchasing data to mine actionable navigation patterns. Four modules of this framework are discussed, which are: (1 mapping from the physical space to the cyber space, (2 data preprocessing, (3 pattern mining and (4 knowledge understanding and utilization. In the data preprocessing module, the critical problem of how to capture the mainstream shopping path sequences while wiping out unnecessary redundant and repeated details is addressed in detail. To solve this problem, two types of redundant patterns, i.e., loop repeat pattern and palindrome-contained pattern are recognized and the corresponding processing algorithms are proposed. The experimental results show that the redundant pattern filtering functions are effective and scalable. Overall, this work builds a bridge between indoor positioning and advanced data mining technologies, and provides a feasible way to study customers’ shopping behaviors via multi-source RFID data.

Groundwater potentiality mapping using geoelectrical-based aquifer hydraulic parameters: A GIS-based multi-criteria decision analysis modeling approach

Directory of Open Access Journals (Sweden)

Kehinde Anthony Mogaji Hwee San Lim

2017-01-01

Full Text Available This study conducted a robust analysis on acquired 2D resistivity imaging data and borehole pumping test records to optimize groundwater potentiality mapping in Perak province, Malaysia using derived aquifer hydraulic properties. The transverse resistance (TR parameter was determined from the interpreted 2D resistivity imaging data by applying the Dar-Zarrouk parameter equation. Linear regression and GIS techniques were used to regress the estimated values for TR parameters with the aquifer transmissivity values extracted from the geospatially produced BPT records-based aquifer transmissivity map to develop the aquifer transmissivity parameter predictive (ATPP model. The reliability evaluated ATPP model using the Theil inequality coefficient measurement approach was used to establish geoelectrical-based hydraulic parameters (GHP modeling equations for the modeling of transmissivity (Tr, hydraulic conductivity (K, storativity (St, and hydraulic diffusivity (D properties. The applied GHP modeling equation results to the delineated aquifer media was used to produce aquifer potential conditioning factor maps for Tr, K, St, and D. The maps were modeled to develop an aquifer potential mapping index (APMI model via applying the multi-criteria decision analysis-analytic hierarchy process principle. The area groundwater reservoir productivity potential model map produced based on the processed APMI model estimates in the GIS environment was found to be 71% accurate. This study establishes a good alternative approach to determine aquifer hydraulic parameters even in areas where pumping test information is unavailable using a cost effective geophysical data. The produced map can be explored for hydrological decision making.

Biodiversity mapping in sensitive areas

Energy Technology Data Exchange (ETDEWEB)

Jensen, Tor; Ulssnes, Amund; Nissen-Lie, Torild [DNV, Oslo (Norway)

2008-07-01

When oil companies are entering new unexplored areas their potential footprint on the environment should be measured in a way that necessary action could be included in the planning of the activity. These actions should reduce the impact to accepted levels. Traditional baseline studies, including sediment and macro fauna sampling, are carried out in homogeneous areas. In heterogeneous and unexplored areas there is a need for more information than these traditional sediment analyses can give. To increase the knowledge from specific areas biodiversity mapping has been carried out. To combine the knowledge from ROV surveys, modelling, current measurements, sediment characteristics, seismic, macro fauna and background levels of chemicals contents in the sediments, both prior to the exploration, and after the drilling have taken place the operator can document their footprint on the marine environment. (author)

Activation of Mechanosensitive Transient Receptor Potential/Piezo Channels in Odontoblasts Generates Action Potentials in Cocultured Isolectin B4-negative Medium-sized Trigeminal Ganglion Neurons.

Science.gov (United States)

Sato, Masaki; Ogura, Kazuhiro; Kimura, Maki; Nishi, Koichi; Ando, Masayuki; Tazaki, Masakazu; Shibukawa, Yoshiyuki

2018-04-27

Various stimuli to the dentin surface elicit dentinal pain by inducing dentinal fluid movement causing cellular deformation in odontoblasts. Although odontoblasts detect deformation by the activation of mechanosensitive ionic channels, it is still unclear whether odontoblasts are capable of establishing neurotransmission with myelinated A delta (Aδ) neurons. Additionally, it is still unclear whether these neurons evoke action potentials by neurotransmitters from odontoblasts to mediate sensory transduction in dentin. Thus, we investigated evoked inward currents and evoked action potentials form trigeminal ganglion (TG) neurons after odontoblast mechanical stimulation. We used patch clamp recordings to identify electrophysiological properties and record evoked responses in TG neurons. We classified TG cells into small-sized and medium-sized neurons. In both types of neurons, we observed voltage-dependent inward currents. The currents from medium-sized neurons showed fast inactivation kinetics. When mechanical stimuli were applied to odontoblasts, evoked inward currents were recorded from medium-sized neurons. Antagonists for the ionotropic adenosine triphosphate receptor (P2X 3 ), transient receptor potential channel subfamilies, and Piezo1 channel significantly inhibited these inward currents. Mechanical stimulation to odontoblasts also generated action potentials in the isolectin B 4 -negative medium-sized neurons. Action potentials in these isolectin B 4 -negative medium-sized neurons showed a short duration. Overall, electrophysiological properties of neurons indicate that the TG neurons with recorded evoked responses after odontoblast mechanical stimulation were myelinated Aδ neurons. Odontoblasts established neurotransmission with myelinated Aδ neurons via P2X 3 receptor activation. The results also indicated that mechanosensitive TRP/Piezo1 channels were functionally expressed in odontoblasts. The activation of P2X 3 receptors induced an action potential

Topological mass mechanism and exact fields mapping

International Nuclear Information System (INIS)

Amaral, R L P G; Ventura, O S; Buffon, L O; Costa, J V

2006-01-01

We present a class of mappings between models with topological mass mechanism and purely topological models in arbitrary dimensions. These mappings are established by directly mapping the fields of one model in terms of the fields of the other model in closed expressions. These expressions provide the mappings of their actions as well as the mappings of their propagators. For a general class of models in which the topological model becomes the BF model the mappings present arbitrary functions which otherwise are absent for Chern-Simons like actions. This work generalizes the results of (Ventura O S, Amaral R L P G, Costa J V, Buffon L O and Lemes V E R 2004 J. Phys. A: Math. Gen. 37 11711-23) for arbitrary dimensions

76 FR 21938 - Potential Environmental Impacts of the Proposed Runway 13 Extension and Associated Actions for...

Science.gov (United States)

2011-04-19

... DEPARTMENT OF TRANSPORTATION Federal Aviation Administration Potential Environmental Impacts of the Proposed Runway 13 Extension and Associated Actions for the Devils Lake Regional Airport in Devils Lake, ND AGENCY: Federal Aviation Administration (FAA), Department of Transportation (DOT). ACTION...

Determination of Nerve Fiber Diameter Distribution From Compound Action Potential: A Continuous Approach.

Science.gov (United States)

Un, M Kerem; Kaghazchi, Hamed

2018-01-01

When a signal is initiated in the nerve, it is transmitted along each nerve fiber via an action potential (called single fiber action potential (SFAP)) which travels with a velocity that is related with the diameter of the fiber. The additive superposition of SFAPs constitutes the compound action potential (CAP) of the nerve. The fiber diameter distribution (FDD) in the nerve can be computed from the CAP data by solving an inverse problem. This is usually achieved by dividing the fibers into a finite number of diameter groups and solve a corresponding linear system to optimize FDD. However, number of fibers in a nerve can be measured sometimes in thousands and it is possible to assume a continuous distribution for the fiber diameters which leads to a gradient optimization problem. In this paper, we have evaluated this continuous approach to the solution of the inverse problem. We have utilized an analytical function for SFAP and an assumed a polynomial form for FDD. The inverse problem involves the optimization of polynomial coefficients to obtain the best estimate for the FDD. We have observed that an eighth order polynomial for FDD can capture both unimodal and bimodal fiber distributions present in vivo, even in case of noisy CAP data. The assumed FDD distribution regularizes the ill-conditioned inverse problem and produces good results.

Quantitative analysis of single muscle fibre action potentials recorded at known distances

NARCIS (Netherlands)

Albers, B.A.; Put, J.H.M.; Wallinga, W.; Wirtz, P.

1989-01-01

In vivo records of single fibre action potentials (SFAPs) have always been obtained at unknown distance from the active muscle fibre. A new experimental method has been developed enabling the derivation of the recording distance in animal experiments. A single fibre is stimulated with an

Molecular polarization potential maps of the nucleic acid bases

International Nuclear Information System (INIS)

Alkorta, I.; Perez, J.J.

1996-01-01

Ab initio calculations at the SCF level were carried out to compute the polarization potential map NM of the nucleic acid bases: cytosine, thymine, uracil, adedine, and guanine. For this purpose, the Dunning's 9s5p basis set contracted to a split-valence, was selected to perform the calculations. The molecular polarization potential (MPP) at each point was evaluated by the difference between the interaction energy of the molecule with a unit point charge and the molecular electrostatic potential (MEP) at that point. MEPS and MPPS for the different molecules were computed with a density of 5 points/Angstrom 2 on the van der Waals surface of each molecule, defined using the van der Waals radii. Due to the symmetry of the molecules, only half the points were computed. The total number of points calculated was 558 for cytosine, 621 for thymine, 526 for uracil, 666 for adenine, and 699 for guanine. The results of these calculations are analyzed in terms of their implications on the molecular interactions between pairs of nucleic acid bases. 23 refs., 5 figs., 1 tab

Mapping current and potential distribution of non-native Prosopis juliflora in the Afar region of Ethiopia.

Science.gov (United States)

Wakie, Tewodros T; Evangelista, Paul H; Jarnevich, Catherine S; Laituri, Melinda

2014-01-01

We used correlative models with species occurrence points, Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation indices, and topo-climatic predictors to map the current distribution and potential habitat of invasive Prosopis juliflora in Afar, Ethiopia. Time-series of MODIS Enhanced Vegetation Indices (EVI) and Normalized Difference Vegetation Indices (NDVI) with 250 m2 spatial resolution were selected as remote sensing predictors for mapping distributions, while WorldClim bioclimatic products and generated topographic variables from the Shuttle Radar Topography Mission product (SRTM) were used to predict potential infestations. We ran Maxent models using non-correlated variables and the 143 species- occurrence points. Maxent generated probability surfaces were converted into binary maps using the 10-percentile logistic threshold values. Performances of models were evaluated using area under the receiver-operating characteristic (ROC) curve (AUC). Our results indicate that the extent of P. juliflora invasion is approximately 3,605 km2 in the Afar region (AUC  = 0.94), while the potential habitat for future infestations is 5,024 km2 (AUC  = 0.95). Our analyses demonstrate that time-series of MODIS vegetation indices and species occurrence points can be used with Maxent modeling software to map the current distribution of P. juliflora, while topo-climatic variables are good predictors of potential habitat in Ethiopia. Our results can quantify current and future infestations, and inform management and policy decisions for containing P. juliflora. Our methods can also be replicated for managing invasive species in other East African countries.

Outcome mapping for health system integration

Directory of Open Access Journals (Sweden)

Tsasis P

2013-03-01

Full Text Available Peter Tsasis,1 Jenna M Evans,2 David Forrest,3 Richard Keith Jones4 1School of Health Policy and Management, Faculty of Health, York University, Toronto, Canada; 2Institute of Health Policy, Management and Evaluation, Faculty of Medicine, University of Toronto, Canada; 3Global Vision Consulting Ltd, Victoria, Canada; 4R Keith Jones and Associates, Victoria, Canada Abstract: Health systems around the world are implementing integrated care strategies to improve quality, reduce or maintain costs, and improve the patient experience. Yet few practical tools exist to aid leaders and managers in building the prerequisites to integrated care, namely a shared vision, clear roles and responsibilities, and a common understanding of how the vision will be realized. Outcome mapping may facilitate stakeholder alignment on the vision, roles, and processes of integrated care delivery via participative and focused dialogue among diverse stakeholders on desired outcomes and enabling actions. In this paper, we describe an outcome-mapping exercise we conducted at a Local Health Integration Network in Ontario, Canada, using consensus development conferences. Our preliminary findings suggest that outcome mapping may help stakeholders make sense of a complex system and foster collaborative capital, a resource that can support information sharing, trust, and coordinated change toward integration across organizational and professional boundaries. Drawing from the theoretical perspectives of complex adaptive systems and collaborative capital, we also outline recommendations for future outcome-mapping exercises. In particular, we emphasize the potential for outcome mapping to be used as a tool not only for identifying and linking strategic outcomes and actions, but also for studying the boundaries, gaps, and ties that characterize social networks across the continuum of care. Keywords: integrated care, integrated delivery systems, complex adaptive systems, social capital

Outcome producing potential influences twelve-month-olds' interpretation of a novel action as goal-directed.

Science.gov (United States)

Biro, Szilvia; Verschoor, Stephan; Coalter, Esther; Leslie, Alan M

2014-11-01

Learning about a novel, goal-directed action is a complex process. It requires identifying the outcome of the action and linking the action to its outcome for later use in new situations to predict the action or to anticipate its outcome. We investigated the hypothesis that linking a novel action to a salient change in the environment is critical for infants to assign a goal to the novel action. We report a study in which we show that 12-month-old infants, who were provided with prior experience with a novel action accompanied with a salient visible outcome in one context, can interpret the same action as goal-directed even in the absence of the outcome in another context. Our control condition shows that prior experience with the action, but without the salient effect, does not lead to goal-directed interpretation of the novel action. We also found that, for the case of 9-month-olds infants, prior experience with the outcome producing potential of the novel action does not facilitate a goal-directed interpretation of the action. However, this failure was possibly due to difficulties with generalizing the learnt association to another context rather than with linking the action to its outcome. Copyright © 2014 Elsevier Inc. All rights reserved.

Role of action potential configuration and the contribution of C²⁺a and K⁺ currents to isoprenaline-induced changes in canine ventricular cells.

Science.gov (United States)

Szentandrássy, N; Farkas, V; Bárándi, L; Hegyi, B; Ruzsnavszky, F; Horváth, B; Bányász, T; Magyar, J; Márton, I; Nánási, P P

2012-10-01

Although isoprenaline (ISO) is known to activate several ion currents in mammalian myocardium, little is known about the role of action potential morphology in the ISO-induced changes in ion currents. Therefore, the effects of ISO on action potential configuration, L-type Ca²⁺ current (I(Ca)), slow delayed rectifier K⁺ current (I(Ks)) and fast delayed rectifier K⁺ current (I(Kr)) were studied and compared in a frequency-dependent manner using canine isolated ventricular myocytes from various transmural locations. Action potentials were recorded with conventional sharp microelectrodes; ion currents were measured using conventional and action potential voltage clamp techniques. In myocytes displaying a spike-and-dome action potential configuration (epicardial and midmyocardial cells), ISO caused reversible shortening of action potentials accompanied by elevation of the plateau. ISO-induced action potential shortening was absent in endocardial cells and in myocytes pretreated with 4-aminopyridine. Application of the I(Kr) blocker E-4031 failed to modify the ISO effect, while action potentials were lengthened by ISO in the presence of the I(Ks) blocker HMR-1556. Both action potential shortening and elevation of the plateau were prevented by pretreatment with the I(Ca) blocker nisoldipine. Action potential voltage clamp experiments revealed a prominent slowly inactivating I(Ca) followed by a rise in I(Ks) , both currents increased with increasing the cycle length. The effect of ISO in canine ventricular cells depends critically on action potential configuration, and the ISO-induced activation of I(Ks) - but not I(Kr) - may be responsible for the observed shortening of action potentials. © 2012 The Authors. British Journal of Pharmacology © 2012 The British Pharmacological Society.

A dual potassium channel activator improves repolarization reserve and normalizes ventricular action potentials

DEFF Research Database (Denmark)

Calloe, Kirstine; Di Diego, José M; Hansen, Rie Schultz

2016-01-01

in cultured canine cardiac myocytes and determined whether a dual K(+) current activator can normalize K(+) currents and restore action potential (AP) configuration. METHODS AND RESULTS: Ventricular myocytes were isolated and cultured for up to 48h. Current and voltage clamp recordings were made using patch...... of EADs. Our results suggest a potential benefit of K(+) current activators under conditions of reduced repolarization reserve including heart failure....

Mapping actions to improve access to medicines for mental disorders in low and middle income countries.

Science.gov (United States)

Barbui, C; Dua, T; Kolappa, K; Saraceno, B; Saxena, S

2017-10-01

In recent years a number of intergovernmental initiatives have been activated in order to enhance the capacity of countries to improve access to essential medicines, particularly for mental disorders. In May 2013 the 66th World Health Assembly adopted the World Health Organization (WHO) Comprehensive Mental Health Action Plan 2013-2020, which builds upon the work of WHO's Mental Health Gap Action Programme. Within this programme, evidence-based guidelines for mental disorders were developed, including recommendations on appropriate use of medicines. Subsequently, the 67th World Health Assembly adopted a resolution on access to essential medicines, which urged Member States to improve national policies for the selection of essential medicines and to promote their availability, affordability and appropriate use. Following the precedent set by these important initiatives, this article presents eleven actions for improving access and appropriate use of psychotropic medicines. A 4 × 4 framework mapping actions as a function of the four components of access - selection, availability, affordability and appropriate use - and across four different health care levels, three of which belong to the supply side and one to the demand side, was developed. The actions are: developing a medicine selection process; promoting information and education activities for staff and end-users; developing a medicine regulation process; implementing a reliable supply system; implementing a reliable quality-control system; developing a community-based system of mental health care and promoting help-seeking behaviours; developing international agreements on medicine affordability; developing pricing policies and a sustainable financing system; developing or adopting evidence-based guidelines; monitoring the use of psychotropic medicines; promoting training initiatives for staff and end-users on critical appraisal of scientific evidence and appropriate use of psychotropic medicines. Activating

Facilitating participation in formative evaluation supported by effect map

DEFF Research Database (Denmark)

Granlien, Maren Sander

2009-01-01

It has been suggested that formative evaluation should be an integrated part of system implementation in order to improve the outcome of system use. In a design project an approach combining participatory design (PD) and formative evaluation has shown a great potential for improving the design of...... map is applied in an action research study in the Danish health care sector aiming at improving the medication process and the use of the electronic medication record supporting the medication process. ...... designed effect map. The purpose of the effect map is twofold: a) To encourage user participation in the early activities of formative evaluation b) The effects specified can be used as formative evaluation measures and guidance in the process of improving the system. The evaluation approach and the effect...

Action potential propagation recorded from single axonal arbors using multi-electrode arrays.

Science.gov (United States)

Tovar, Kenneth R; Bridges, Daniel C; Wu, Bian; Randall, Connor; Audouard, Morgane; Jang, Jiwon; Hansma, Paul K; Kosik, Kenneth S

2018-04-11

We report the presence of co-occurring extracellular action potentials (eAPs) from cultured mouse hippocampal neurons among groups of planar electrodes on multi-electrode arrays (MEAs). The invariant sequences of eAPs among co-active electrode groups, repeated co-occurrences and short inter-electrode latencies are consistent with action potential propagation in unmyelinated axons. Repeated eAP co-detection by multiple electrodes was widespread in all our data records. Co-detection of eAPs confirms they result from the same neuron and allows these eAPs to be isolated from all other spikes independently of spike sorting algorithms. We averaged co-occurring events and revealed additional electrodes with eAPs that would otherwise be below detection threshold. We used these eAP cohorts to explore the temperature sensitivity of action potential propagation and the relationship between voltage-gated sodium channel density and propagation velocity. The sequence of eAPs among co-active electrodes 'fingerprints' neurons giving rise to these events and identifies them within neuronal ensembles. We used this property and the non-invasive nature of extracellular recording to monitor changes in excitability at multiple points in single axonal arbors simultaneously over several hours, demonstrating independence of axonal segments. Over several weeks, we recorded changes in inter-electrode propagation latencies and ongoing changes in excitability in different regions of single axonal arbors. Our work illustrates how repeated eAP co-occurrences can be used to extract physiological data from single axons with low electrode density MEAs. However, repeated eAP co-occurrences leads to over-sampling spikes from single neurons and thus can confound traditional spike-train analysis.

Mapping optimal areas of ecosystem services potential in Vilnius (Lithuania)

Science.gov (United States)

Pereira, Paulo; Depellegrin, Daniel; Misiune, Ieva; Cerda, Artemi

2016-04-01

Maps are fundamental to understand the spatial pattern of natural and human impacts on the landscape (Brevik et al., 2016; Lavado Contador et al., 2009; Pereira et al., 2010a,b). Urban areas are subjected to an intense human pressure (Beniston et al., 2015), contributing to the degradation of the ecosystems, reducing their capacity to provide services in quality and quantity (Requier-Desjardins et al., 2011; Zhang et al., 2011). Environments that can provide a high number and quality of ecosystem services (ES) must be identified and managed correctly, since are spaces that can mitigate the impacts of human settlements and improve their quality. thus is of major importance have identify the areas that can provide better ES (Deppelegrin and Pereira, 2015). The aim of this work is to identify areas with high ES potential in Vilnius city. Here, we identified a total of 4 different land uses, agricultural areas (32.48%), water bodies (1.46%), forest and semi-natural (31.91%) areas and artificial surfaces (34.16%). CORINE land cover 2006 was used as base information to classify ES potential. The assessment of each land cover potential was carried out using expert assessment. Each land use type was ranked from 0 (no potential) to 5 (High potential). In this work the sum of total regulating, providing and cultural ES were assessed. The areas with optimal ES were the ones with the sum of all ranks equal or higher than the 3rd Quartil of each distribution. After identifying these areas, data was mapped using ArcGIS software. The results showed that on average Vilnius city has a higher potential for regulating services (20.35±15.92), followed by cultural (14.43±8.81) and providing (14.26±8.87). There was a significant correlation among the different type of services. Regulating vs cultural (0.92, p<0.001), regulating vs providing (0.72, p<0.001) and providing vs cultural (0.65, p<0.001). The results of Morans I autocorrelation index showed that regulating (Z-score: 10

Application of Volta potential mapping to determine metal surface defects

International Nuclear Information System (INIS)

Nazarov, A.; Thierry, D.

2007-01-01

As a rule, stress or fatigue cracks originate from various surface imperfections, such as pits, inclusions or locations showing a residual stress. It would be very helpful for material selection to be able to predict the likelihood of environment-assisted cracking or pitting corrosion. By using Scanning Kelvin Probe (the vibrating capacitor with a spatial resolution of 80 μm) the profiling of metal electron work function (Volta potential) in air is applied to the metal surfaces showing residual stress, MnS inclusions and wearing. The Volta potential is influenced by the energy of electrons at the Fermi level and drops generally across the metal/oxide/air interfaces. Inclusions (e.g. MnS) impair continuity of the passive film that locally decreases Volta potential. The stress applied gives rise to dislocations, microcracks and vacancies in the metal and the surface oxide. The defects decrease Volta and corrosion potentials; reduce the overvoltage for processes of passivity breakdown and anodic metal dissolution. These 'anodic' defects can be visualized in potential mapping that can help us to predict locations with higher risk of pitting corrosion or cracking

The human ether-a-go-go-related gene (hERG) current inhibition selectively prolongs action potential of midmyocardial cells to augment transmural dispersion.

Science.gov (United States)

Yasuda, C; Yasuda, S; Yamashita, H; Okada, J; Hisada, T; Sugiura, S

2015-08-01

The majority of drug induced arrhythmias are related to the prolongation of action potential duration following inhibition of rapidly activating delayed rectifier potassium current (I(Kr)) mediated by the hERG channel. However, for arrhythmias to develop and be sustained, not only the prolongation of action potential duration but also its transmural dispersion are required. Herein, we evaluated the effect of hERG inhibition on transmural dispersion of action potential duration using the action potential clamp technique that combined an in silico myocyte model with the actual I(Kr) measurement. Whole cell I(Kr) current was measured in Chinese hamster ovary cells stably expressing the hERG channel. The measured current was coupled with models of ventricular endocardial, M-, and epicardial cells to calculate the action potentials. Action potentials were evaluated under control condition and in the presence of 1, 10, or 100 μM disopyramide, an hERG inhibitor. Disopyramide dose-dependently increased the action potential durations of the three cell types. However, action potential duration of M-cells increased disproportionately at higher doses, and was significantly different from that of epicardial and endocardial cells (dispersion of repolarization). By contrast, the effects of disopyramide on peak I(Kr) and instantaneous current-voltage relation were similar in all cell types. Simulation study suggested that the reduced repolarization reserve of M-cell with smaller amount of slowly activating delayed rectifier potassium current levels off at longer action potential duration to make such differences. The action potential clamp technique is useful for studying the mechanism of arrhythmogenesis by hERG inhibition through the transmural dispersion of repolarization.

Anti-addiction Drug Ibogaine Prolongs the Action Potential in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes.

Science.gov (United States)

Rubi, Lena; Eckert, Daniel; Boehm, Stefan; Hilber, Karlheinz; Koenig, Xaver

2017-04-01

Ibogaine is a plant alkaloid used as anti-addiction drug in dozens of alternative medicine clinics worldwide. Recently, alarming reports of life-threatening cardiac arrhythmias and cases of sudden death associated with the ingestion of ibogaine have accumulated. Using whole-cell patch clamp recordings, we assessed the effects of ibogaine and its main metabolite noribogaine on action potentials in human ventricular-like cardiomyocytes derived from induced pluripotent stem cells. Therapeutic concentrations of ibogaine and its long-lived active metabolite noribogaine significantly retarded action potential repolarization in human cardiomyocytes. These findings represent the first experimental proof that ibogaine application entails a cardiac arrhythmia risk for humans. In addition, they explain the clinically observed delayed incidence of cardiac adverse events several days after ibogaine intake. We conclude that therapeutic concentrations of ibogaine retard action potential repolarization in the human heart. This may give rise to a prolongation of the QT interval in the electrocardiogram and cardiac arrhythmias.

Integrating future scenario‐based crop expansion and crop conditions to map switchgrass biofuel potential in eastern Nebraska, USA

Science.gov (United States)

Gu, Yingxin; Wylie, Bruce K.

2018-01-01

Switchgrass (Panicum virgatum) has been evaluated as one potential source for cellulosic biofuel feedstocks. Planting switchgrass in marginal croplands and waterway buffers can reduce soil erosion, improve water quality, and improve regional ecosystem services (i.e. it serves as a potential carbon sink). In previous studies, we mapped high risk marginal croplands and highly erodible cropland buffers that are potentially suitable for switchgrass development, which would improve ecosystem services and minimally impact food production. In this study, we advance our previous study results and integrate future crop expansion information to develop a switchgrass biofuel potential ensemble map for current and future croplands in eastern Nebraska. The switchgrass biomass productivity and carbon benefits (i.e. NEP: net ecosystem production) for the identified biofuel potential ensemble areas were quantified. The future scenario‐based (‘A1B’) land use and land cover map for 2050, the US Geological Survey crop type and Compound Topographic Index (CTI) maps, and long‐term (1981–2010) averaged annual precipitation data were used to identify future crop expansion regions that are suitable for switchgrass development. Results show that 2528 km2 of future crop expansion regions (~3.6% of the study area) are potentially suitable for switchgrass development. The total estimated biofuel potential ensemble area (including cropland buffers, marginal croplands, and future crop expansion regions) is 4232 km2 (~6% of the study area), potentially producing 3.52 million metric tons of switchgrass biomass per year. Converting biofuel ensemble regions to switchgrass leads to potential carbon sinks (the total NEP for biofuel potential areas is 0.45 million metric tons C) and is environmentally sustainable. Results from this study improve our understanding of environmental conditions and ecosystem services of current and future cropland systems in eastern Nebraska and provide

Mapping current and potential distribution of non-native Prosopis juliflora in the Afar region of Ethiopia.

Directory of Open Access Journals (Sweden)

Tewodros T Wakie

Full Text Available We used correlative models with species occurrence points, Moderate Resolution Imaging Spectroradiometer (MODIS vegetation indices, and topo-climatic predictors to map the current distribution and potential habitat of invasive Prosopis juliflora in Afar, Ethiopia. Time-series of MODIS Enhanced Vegetation Indices (EVI and Normalized Difference Vegetation Indices (NDVI with 250 m2 spatial resolution were selected as remote sensing predictors for mapping distributions, while WorldClim bioclimatic products and generated topographic variables from the Shuttle Radar Topography Mission product (SRTM were used to predict potential infestations. We ran Maxent models using non-correlated variables and the 143 species- occurrence points. Maxent generated probability surfaces were converted into binary maps using the 10-percentile logistic threshold values. Performances of models were evaluated using area under the receiver-operating characteristic (ROC curve (AUC. Our results indicate that the extent of P. juliflora invasion is approximately 3,605 km2 in the Afar region (AUC  = 0.94, while the potential habitat for future infestations is 5,024 km2 (AUC  = 0.95. Our analyses demonstrate that time-series of MODIS vegetation indices and species occurrence points can be used with Maxent modeling software to map the current distribution of P. juliflora, while topo-climatic variables are good predictors of potential habitat in Ethiopia. Our results can quantify current and future infestations, and inform management and policy decisions for containing P. juliflora. Our methods can also be replicated for managing invasive species in other East African countries.

Developing index maps of water-harvest potential in Africa

Science.gov (United States)

Senay, G.B.; Verdin, J.P.

2004-01-01

The food security problem in Africa is tied to the small farmer, whose subsistence farming relies heavily on rain-fed agriculture. A dry spell lasting two to three weeks can cause a significant yield reduction. A small-scale irrigation scheme from small-capacity ponds can alleviate this problem. This solution would require a water harvest mechanism at a farm level. In this study, we looked at the feasibility of implementing such a water harvest mechanism in drought prone parts of Africa. A water balance study was conducted at different watershed levels. Runoff (watershed yield) was estimated using the SCS curve number technique and satellite derived rainfall estimates (RFE). Watersheds were delineated from the Africa-wide HYDRO-1K digital elevation model (DEM) data set in a GIS environment. Annual runoff volumes that can potentially be stored in a pond during storm events were estimated as the product of the watershed area and runoff excess estimated from the SCS Curve Number method. Estimates were made for seepage and net evaporation losses. A series of water harvest index maps were developed based on a combination of factors that took into account the availability of runoff, evaporation losses, population density, and the required watershed size needed to fill a small storage reservoir that can be used to alleviate water stress during a crop growing season. This study presents Africa-wide water-harvest index maps that could be used for conducting feasibility studies at a regional scale in assessing the relative differences in runoff potential between regions for the possibility of using ponds as a water management tool. ?? 2004 American Society of Agricultural Engineers.

Action Research’s Potential to Foster Institutional Change for Urban Water Management

Directory of Open Access Journals (Sweden)

Dimitrios Zikos

2013-04-01

Full Text Available The paper discusses the potential of action research to meet the challenges entailed in institutional design for urban water management. Our overall aim is to briefly present action research and discuss its methodological merits with regard to the challenges posed by the different conceptual bases for extrapolating the effects of institutional design on institutional change. Thus, our aim is to explore how Action Research meets the challenge of scoping the field in an open fashion for determining the appropriate mechanisms of institutional change and supporting the emerging of new water institutions. To accomplish this aim, we select the Water Framework Directive (WFD as an illustrative driving force requiring changes in water management practices and implying the need for the emergence of new institutions. We employ a case of urban water management in the Volos Metropolitan Area, part of the Thessaly region in Greece, where a Pilot River Basin Plan was implemented. By applying action research and being involved in a long process of interaction between stakeholders, we examine the emergence of new institutions dealing with urban water management under the general principles of the major driving force for change: the WFD.

Event-related potential effects of superior action anticipation in professional badminton players.

Science.gov (United States)

Jin, Hua; Xu, Guiping; Zhang, John X; Gao, Hongwei; Ye, Zuoer; Wang, Pin; Lin, Huiyan; Mo, Lei; Lin, Chong-De

2011-04-04

The ability to predict the trajectory of a ball based on the opponent's body kinematics has been shown to be critical to high-performing athletes in many sports. However, little is known about the neural correlates underlying such superior ability in action anticipation. The present event-related potential study compared brain responses from professional badminton players and non-player controls when they watched video clips of badminton games and predicted a ball's landing position. Replicating literature findings, the players made significantly more accurate judgments than the controls and showed better action anticipation. Correspondingly, they showed enlarged amplitudes of two ERP components, a P300 peaking around 350ms post-stimulus with a parietal scalp distribution and a P2 peaking around 250ms with a posterior-occipital distribution. The P300 effect was interpreted to reflect primed access and/or directing of attention to game-related memory representations in the players facilitating their online judgment of related actions. The P2 effect was suggested to reflect some generic learning effects. The results identify clear neural responses that differentiate between different levels of action anticipation associated with sports expertise. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

A fixed-point theorem for holomorphic maps

OpenAIRE

TIMONEY, RICHARD

1994-01-01

PUBLISHED We consider the action on the maximal ideal space M of the algebra H of bounded analytic functions, induced by an analytic self?map of a complex manifold, X. After some general preliminaries, we focus on the question of the existence of fixed points for this action, in the case when X is the open unit disk, D. We classify the fixed?point?free M?obius transformations, and we show that for an arbitrary analytic map from D into itself, the induced map has a fixed poin...

OECA Annual Report 2015 Map Service

Data.gov (United States)

U.S. Environmental Protection Agency — This interactive map shows information on enforcement actions and cases from 2015. They include civil enforcement actions taken by EPA at facilities, criminal cases...

Mapping industrial networks as an approach to identify inter-organisational collaborative potential in new product development

DEFF Research Database (Denmark)

Parraguez, Pedro; Maier, Anja

2012-01-01

. Consequently, identifying and selecting potential partners to establish collaboration agreements can be a key activity in the new product development process. This paper explores the implications of mapping industrial networks with the purpose of identifying inter-organisational collaborative potential...

An extended action for the effective field theory of dark energy: a stability analysis and a complete guide to the mapping at the basis of EFTCAMB

International Nuclear Information System (INIS)

Frusciante, Noemi; Papadomanolakis, Georgios; Silvestri, Alessandra

2016-01-01

We present a generalization of the effective field theory (EFT) formalism for dark energy and modified gravity models to include operators with higher order spatial derivatives. This allows the extension of the EFT framework to a wider class of gravity theories such as Hořava gravity. We present the corresponding extended action, both in the EFT and the Arnowitt-Deser-Misner (ADM) formalism, and proceed to work out a convenient mapping between the two, providing a self contained and general procedure to translate a given model of gravity into the EFT language at the basis of the Einstein-Boltzmann solver EFTCAMB. Putting this mapping at work, we illustrate, for several interesting models of dark energy and modified gravity, how to express them in the ADM notation and then map them into the EFT formalism. We also provide for the first time, the full mapping of GLPV models into the EFT framework. We next perform a thorough analysis of the physical stability of the generalized EFT action, in absence of matter components. We work out viability conditions that correspond to the absence of ghosts and modes that propagate with a negative speed of sound in the scalar and tensor sector, as well as the absence of tachyonic modes in the scalar sector. Finally, we extend and generalize the phenomenological basis in terms of α-functions introduced to parametrize Horndeski models, to cover all theories with higher order spatial derivatives included in our extended action. We elaborate on the impact of the additional functions on physical quantities, such as the kinetic term and the speeds of propagation for scalar and tensor modes.

Analysis of electrically evoked compound action potential of the auditory nerve in children with bilateral cochlear implants.

Science.gov (United States)

Caldas, Fernanda Ferreira; Cardoso, Carolina Costa; Barreto, Monique Antunes de Souza Chelminski; Teixeira, Marina Santos; Hilgenberg, Anacléia Melo da Silva; Serra, Lucieny Silva Martins; Bahmad Junior, Fayez

2016-01-01

The cochlear implant device has the capacity to measure the electrically evoked compound action potential of the auditory nerve. The neural response telemetry is used in order to measure the electrically evoked compound action potential of the auditory nerve. To analyze the electrically evoked compound action potential, through the neural response telemetry, in children with bilateral cochlear implants. This is an analytical, prospective, longitudinal, historical cohort study. Six children, aged 1-4 years, with bilateral cochlear implant were assessed at five different intervals during their first year of cochlear implant use. There were significant differences in follow-up time (p=0.0082) and electrode position (p=0.0019) in the T-NRT measure. There was a significant difference in the interaction between time of follow-up and electrode position (p=0.0143) when measuring the N1-P1 wave amplitude between the three electrodes at each time of follow-up. The electrically evoked compound action potential measurement using neural response telemetry in children with bilateral cochlear implants during the first year of follow-up was effective in demonstrating the synchronized bilateral development of the peripheral auditory pathways in the studied population. Copyright © 2015 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Calibration is action specific but perturbation of perceptual units is not.

Science.gov (United States)

Pan, Jing S; Coats, Rachel O; Bingham, Geoffrey P

2014-02-01

G. P. Bingham and C. C. Pagano (1998, The necessity of a perception/action approach to definite distance perception: Monocular distance perception to guide reaching. Journal of Experimental Psychology: Human Perception and Performance, 24, 145-168) argued that metric space perception should be investigated using relevant action measures because calibration is an intrinsic component of perception/action that yields accurate targeted actions. They described calibration as a mapping from embodied units of perception to embodied units of action. This mapping theory yields a number of predictions. We tested two of them. The first prediction is that calibration should be action specific because what is calibrated is a mapping from perceptual units to a unit of action. Thus, calibration does not generalize to other actions. This prediction is consistent with the "action-specific approach" to calibration (D. R. Proffitt, 2008, An action specific approach to spatial perception. In R. L. Klatzky, B. MacWhinney, & M. Behrmann (Eds.), Embodiment, ego-space and action (pp. 179-202). New York, NY: Psychology Press.). The second prediction is that a change in perceptual units should generalize to all relevant actions that are guided using that perceptual information. The same perceptual units can be mapped to different actions. Change in the unit affects all relevant actions. This prediction is consistent with the "general purpose perception approach" (J. M. Loomis & J. W. Philbeck, 2008, Measuring spatial perception with spatial updating and action. In R. L. Klatzky, B. MacWhinney, & M. Behrmann (Eds.), Embodiment, ego-space and action (pp. 1-43). New York, NY: Psychology Press). In Experiment 1, two targeted actions, throwing and extended reaching were tested to determine if they were comparable in precision and in response to distorted calibration. They were. Comparing these actions, the first prediction was tested in Experiment 2 and confirmed. The second prediction was

Atlas of the Colombian coal, Potential map and rank: Map 5-09; Atlas de los carbones colombianos. Mapa de potencial y rango: Plancha 5-09

Energy Technology Data Exchange (ETDEWEB)

Pulido Gonzalez, Orlando

1999-07-01

With the presentation of the Atlas of Coal to scale 1:500.000, it is sought to show to big features the location of the different areas with coal in Colombia, associating with the geologic units, the potential and the range. In the Map 5-09, the formations that include the coal are defined as Umir, Guaduas, Limbo, (Los Cuervos), San Fernando, (Carbonera), defined as Kst, Ksgt and Pgt. For the potential an arbitrary scale settled down, in the following way: in the first place bigger to 1000 million tons; between 1000 and 100; between 100 and 10 and lastly smaller to 10 million tons. These figures are represented in the map by triangles with colors that they are equal before to the figures mentioned. Keeping in mind the scale, it was opted to report the potential in the category of the hypothetical resources; when the resources or reserves are established, they are also reported. As for the range, in the map it is indicated by means of symbols that should be taken as a domain or tendency of the coal in each area in general. The the coal rank understood as the transformation that has reached along the geologic evolution is what is mentioned as anthracitic coal, semi-anthracitic, bituminous low in volatile, bituminous middle in volatile, bituminous high in volatile A, B and C, sub-bituminous and lastly the lignite. For each map are mentioned that there are determined.

Action Learning: Avoiding Conflict or Enabling Action

Science.gov (United States)

Corley, Aileen; Thorne, Ann

2006-01-01

Action learning is based on the premise that action and learning are inextricably entwined and it is this potential, to enable action, which has contributed to the growth of action learning within education and management development programmes. However has this growth in action learning lead to an evolution or a dilution of Revan's classical…

Radiometric maps of Israel - Partial contribution to the understanding of potential radon emanations

International Nuclear Information System (INIS)

Vulkan, U.; Shirav, M.

1997-01-01

An airborne radiometric survey over parts of Israel was carried out in 1981. The system was comprised from 10 Nal 4 inch x 4 inch x 16 inch detectors, arranged in 4,4 and 2 sensors, with total volume of 1560 inch 3 , and one 4 inch x 4 inch x 16 inch uplooking Nal detector. Flight nominal height was 400 feet. It was found that the Mount Scopus Group (of Senonian origin) is the main source for high uranium - phosphorite rocks of this group contain up to 150 ppm U. Comparing the eU radiometric map with a map of potential radon emanation from rock units, reveals a fair correlation - high radon emanation usually follow the distribution of the Mount Scopus Group in Israel. The correlation between the two maps is excellent over arid terrain where soil cover is missing, whereas over semi-arid - humid areas (western and northern Israel), where soil and cultivation covers are developed, the eU levels over Mount Scopus Group's outcrops are much lower due to absorption of the radiation, and do not depict the full radon potential. Detailed mapping of radon hazards usually exhibit poor correlation between airborne eU data and direct pore radon measurements, even in arid terrain. This phenomenon is attributed to the fact that a radon ''source rock'' (e.g. phosphorite) could be covered with a few up to some tenths of meters of uranium-barren rock. About 0.5 meter cover is enough to absorb all radiation, causing very low airborne eU readings, while the radon free way in this rock is about 10 meters, yielding high pore radon levels when directly measured

Beat-to-beat variability of cardiac action potential duration: underlying mechanism and clinical implications.

Science.gov (United States)

Nánási, Péter P; Magyar, János; Varró, András; Ördög, Balázs

2017-10-01

Beat-to-beat variability of cardiac action potential duration (short-term variability, SV) is a common feature of various cardiac preparations, including the human heart. Although it is believed to be one of the best arrhythmia predictors, the underlying mechanisms are not fully understood at present. The magnitude of SV is basically determined by the intensity of cell-to-cell coupling in multicellular preparations and by the duration of the action potential (APD). To compensate for the APD-dependent nature of SV, the concept of relative SV (RSV) has been introduced by normalizing the changes of SV to the concomitant changes in APD. RSV is reduced by I Ca , I Kr , and I Ks while increased by I Na , suggesting that ion currents involved in the negative feedback regulation of APD tend to keep RSV at a low level. RSV is also influenced by intracellular calcium concentration and tissue redox potential. The clinical implications of APD variability is discussed in detail.

Just do it: action-dependent learning allows sensory prediction.

Directory of Open Access Journals (Sweden)

Itai Novick

Full Text Available Sensory-motor learning is commonly considered as a mapping process, whereby sensory information is transformed into the motor commands that drive actions. However, this directional mapping, from inputs to outputs, is part of a loop; sensory stimuli cause actions and vice versa. Here, we explore whether actions affect the understanding of the sensory input that they cause. Using a visuo-motor task in humans, we demonstrate two types of learning-related behavioral effects. Stimulus-dependent effects reflect stimulus-response learning, while action-dependent effects reflect a distinct learning component, allowing the brain to predict the forthcoming sensory outcome of actions. Together, the stimulus-dependent and the action-dependent learning components allow the brain to construct a complete internal representation of the sensory-motor loop.

Simulating the Epidemiological and Economic Impact of Paratuberculosis Control Actions in Dairy Cattle

DEFF Research Database (Denmark)

Kirkeby, Carsten Thure; Græsbøll, Kaare; Nielsen, Søren Saxmose

2016-01-01

We describe a new mechanistic bioeconomic model for simulating the spread of Mycobacterium avium subsp. paratuberculosis (MAP) within a dairy cattle herd. The model includes age-dependent susceptibility for infection; age-dependent sensitivity for detection; environmental MAP build up in five...... control actions from the Danish MAP control program, it was not economically attractive since the expenses for the control actions outweigh the benefits. Furthermore, the three most popular control actions against the spread of MAP on the farm were found to be costly and inefficient in lowering...

Compound sensory action potential in normal and pathological human nerves

DEFF Research Database (Denmark)

Krarup, Christian

2004-01-01

The compound sensory nerve action potential (SNAP) is the result of phase summation and cancellation of single fiber potentials (SFAPs) with amplitudes that depend on fiber diameter, and the amplitude and shape of the SNAP is determined by the distribution of fiber diameters. Conduction velocities...... dispersion over increasing conduction distance is greater for the SNAP than CMAP, and demonstration of conduction block is therefore difficult. In addition, the effect of temporal dispersion on amplitude and shape is strongly dependent on the number of conducting fibers and their distribution, and......, with fiber loss or increased conduction velocity variability changes of the SNAP may be smaller than expected from normal nerve. The biophysical characteristics of sensory and motor fibers differ, and this may to some extent determine divergent pathophysiological changes in sensory and motor fibers...

Effect of an Educational Game on University Students' Learning about Action Potentials

Science.gov (United States)

Luchi, Kelly Cristina Gaviao; Montrezor, Luís Henrique; Marcondes, Fernanda K.

2017-01-01

The aim of this study was to evaluate the effect of an educational game that is used for teaching the mechanisms of the action potentials in cell membranes. The game was composed of pieces representing the intracellular and extracellular environments, ions, ion channels, and the Na+-K+-ATPase pump. During the game activity, the students arranged…

Action potential conduction between a ventricular cell model and an isolated ventricular cell

NARCIS (Netherlands)

Wilders, R.; Kumar, R.; Joyner, R. W.; Jongsma, H. J.; Verheijck, E. E.; Golod, D.; van Ginneken, A. C.; Goolsby, W. N.

1996-01-01

We used the Luo and Rudy (LR) mathematical model of the guinea pig ventricular cell coupled to experimentally recorded guinea pig ventricular cells to investigate the effects of geometrical asymmetry on action potential propagation. The overall correspondence of the LR cell model with the recorded

Pathological prolongation of action potential duration as a cause of the reduced alpha-adrenoceptor-mediated negative inotropy in streptozotocin-induced diabetic mice myocardium.

Science.gov (United States)

Kanae, Haruna; Hamaguchi, Shogo; Wakasugi, Yumi; Kusakabe, Taichi; Kato, Keisuke; Namekata, Iyuki; Tanaka, Hikaru

2017-11-01

Effect of pathological prolongation of action potential duration on the α-adrenoceptor-mediated negative inotropy was studied in streptozotocin-induced diabetic mice myocardium. In streptozotocin-treated mouse ventricular myocardium, which had longer duration of action potential than that in control mice, the negative inotropic response induced by phenylephrine was smaller than that in control mice. 4-Aminopyridine prolonged the action potential duration and decreased the negative inotropy in control mice. Cromakalim shortened the action potential duration and increased the negative inotropy in streptozotocin-treated mice. These results suggest that the reduced α-adrenoceptor-mediated inotropy in the diabetic mouse myocardium is partly due to its prolonged action potential. Copyright © 2017 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

Teachers in Action Research: Assumptions and Potentials

Science.gov (United States)

Li, Yuen-Ling

2008-01-01

Research literature has long indicated that action research may stimulate practitioners themselves to actively evaluate the quality of their practice. This study is designed to report the use of action research for the development of early years professional practice by analyzing the pre-project and the post-project video-filmed teaching events.…

Mapping Current and Potential Distribution of Non-Native Prosopis juliflora in the Afar Region of Ethiopia

OpenAIRE

Wakie, Tewodros T.; Evangelista, Paul H.; Jarnevich, Catherine S.; Laituri, Melinda

2014-01-01

We used correlative models with species occurrence points, Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation indices, and topo-climatic predictors to map the current distribution and potential habitat of invasive Prosopis juliflora in Afar, Ethiopia. Time-series of MODIS Enhanced Vegetation Indices (EVI) and Normalized Difference Vegetation Indices (NDVI) with 250 m2 spatial resolution were selected as remote sensing predictors for mapping distributions, while WorldClim bioclim...

An Excel‐based implementation of the spectral method of action potential alternans analysis

Science.gov (United States)

Pearman, Charles M.

2014-01-01

Abstract Action potential (AP) alternans has been well established as a mechanism of arrhythmogenesis and sudden cardiac death. Proper interpretation of AP alternans requires a robust method of alternans quantification. Traditional methods of alternans analysis neglect higher order periodicities that may have greater pro‐arrhythmic potential than classical 2:1 alternans. The spectral method of alternans analysis, already widely used in the related study of microvolt T‐wave alternans, has also been used to study AP alternans. Software to meet the specific needs of AP alternans analysis is not currently available in the public domain. An AP analysis tool is implemented here, written in Visual Basic for Applications and using Microsoft Excel as a shell. This performs a sophisticated analysis of alternans behavior allowing reliable distinction of alternans from random fluctuations, quantification of alternans magnitude, and identification of which phases of the AP are most affected. In addition, the spectral method has been adapted to allow detection and quantification of higher order regular oscillations. Analysis of action potential morphology is also performed. A simple user interface enables easy import, analysis, and export of collated results. PMID:25501439

Mapping social networks in software process improvement

DEFF Research Database (Denmark)

Tjørnehøj, Gitte; Nielsen, Peter Axel

2005-01-01

Software process improvement in small, agile organizations is often problematic. Model-based approaches seem to overlook problems. We have been seeking an alternative approach to overcome this through action research. Here we report on a piece of action research from which we developed an approach...... to map social networks and suggest how it can be used in software process improvement. We applied the mapping approach in a small software company to support the realization of new ways of improving software processes. The mapping approach was found useful in improving social networks, and thus furthers...... software process improvement....

The activity of spontaneous action potentials in developing hair cells is regulated by Ca(2+-dependence of a transient K+ current.

Directory of Open Access Journals (Sweden)

Snezana Levic

Full Text Available Spontaneous action potentials have been described in developing sensory systems. These rhythmic activities may have instructional roles for the functional development of synaptic connections. The importance of spontaneous action potentials in the developing auditory system is underpinned by the stark correlation between the time of auditory system functional maturity, and the cessation of spontaneous action potentials. A prominent K(+ current that regulates patterning of action potentials is I(A. This current undergoes marked changes in expression during chicken hair cell development. Although the properties of I(A are not normally classified as Ca(2+-dependent, we demonstrate that throughout the development of chicken hair cells, I(A is greatly reduced by acute alterations of intracellular Ca(2+. As determinants of spike timing and firing frequency, intracellular Ca(2+ buffers shift the activation and inactivation properties of the current to more positive potentials. Our findings provide evidence to demonstrate that the kinetics and functional expression of I(A are tightly regulated by intracellular Ca(2+. Such feedback mechanism between the functional expression of I(A and intracellular Ca(2+ may shape the activity of spontaneous action potentials, thus potentially sculpting synaptic connections in an activity-dependent manner in the developing cochlea.

Voltage Gated Calcium Channel Activation by Backpropagating Action Potentials Downregulates NMDAR Function

Directory of Open Access Journals (Sweden)

Anne-Kathrin Theis

2018-04-01

Full Text Available The majority of excitatory synapses are located on dendritic spines of cortical glutamatergic neurons. In spines, compartmentalized Ca2+ signals transduce electrical activity into specific long-term biochemical and structural changes. Action potentials (APs propagate back into the dendritic tree and activate voltage gated Ca2+ channels (VGCCs. For spines, this global mode of spine Ca2+ signaling is a direct biochemical feedback of suprathreshold neuronal activity. We previously demonstrated that backpropagating action potentials (bAPs result in long-term enhancement of spine VGCCs. This activity-dependent VGCC plasticity results in a large interspine variability of VGCC Ca2+ influx. Here, we investigate how spine VGCCs affect glutamatergic synaptic transmission. We combined electrophysiology, two-photon Ca2+ imaging and two-photon glutamate uncaging in acute brain slices from rats. T- and R-type VGCCs were the dominant depolarization-associated Ca2+conductances in dendritic spines of excitatory layer 2 neurons and do not affect synaptic excitatory postsynaptic potentials (EPSPs measured at the soma. Using two-photon glutamate uncaging, we compared the properties of glutamatergic synapses of single spines that express different levels of VGCCs. While VGCCs contributed to EPSP mediated Ca2+ influx, the amount of EPSP mediated Ca2+ influx is not determined by spine VGCC expression. On a longer timescale, the activation of VGCCs by bAP bursts results in downregulation of spine NMDAR function.

CONSTRUCTING FEMINISTS MAPS OF GOIÂNIA CITY

OpenAIRE

Cabral, Talita

2018-01-01

The goal is to construct maps of feminists actions in Goiania(GO). The chosen methodology use stories of leadership, by means of semi structured interviews with thirteen feminists and the interactive mapping techniques.  Were mapped the places and routes considerate important in the woman fight.

Blanding’s Turtle (Emydoidea blandingii Potential Habitat Mapping Using Aerial Orthophotographic Imagery and Object Based Classification

Directory of Open Access Journals (Sweden)

Douglas J. King

2012-01-01

Full Text Available Blanding’s turtle (Emydoidea blandingii is a threatened species under Canada’s Species at Risk Act. In southern Québec, field based inventories are ongoing to determine its abundance and potential habitat. The goal of this research was to develop means for mapping of potential habitat based on primary habitat attributes that can be detected with high-resolution remotely sensed imagery. Using existing spring leaf-off 20 cm resolution aerial orthophotos of a portion of Gatineau Park where some Blanding’s turtle observations had been made, habitat attributes were mapped at two scales: (1 whole wetlands; (2 within wetland habitat features of open water, vegetation (used for camouflage and thermoregulation, and logs (used for spring sun-basking. The processing steps involved initial pixel-based classification to eliminate most areas of non-wetland, followed by object-based segmentations and classifications using a customized rule sequence to refine the wetland map and to map the within wetland habitat features. Variables used as inputs to the classifications were derived from the orthophotos and included image brightness, texture, and segmented object shape and area. Independent validation using field data and visual interpretation showed classification accuracy for all habitat attributes to be generally over 90% with a minimum of 81.5% for the producer’s accuracy of logs. The maps for each attribute were combined to produce a habitat suitability map for Blanding’s turtle. Of the 115 existing turtle observations, 92.3% were closest to a wetland of the two highest suitability classes. High-resolution imagery combined with object-based classification and habitat suitability mapping methods such as those presented provide a much more spatially explicit representation of detailed habitat attributes than can be obtained through field work alone. They can complement field efforts to document and track turtle activities and can contribute to

Differential roles of two delayed rectifier potassium currents in regulation of ventricular action potential duration and arrhythmia susceptibility.

Science.gov (United States)

Devenyi, Ryan A; Ortega, Francis A; Groenendaal, Willemijn; Krogh-Madsen, Trine; Christini, David J; Sobie, Eric A

2017-04-01

Arrhythmias result from disruptions to cardiac electrical activity, although the factors that control cellular action potentials are incompletely understood. We combined mathematical modelling with experiments in heart cells from guinea pigs to determine how cellular electrical activity is regulated. A mismatch between modelling predictions and the experimental results allowed us to construct an improved, more predictive mathematical model. The balance between two particular potassium currents dictates how heart cells respond to perturbations and their susceptibility to arrhythmias. Imbalances of ionic currents can destabilize the cardiac action potential and potentially trigger lethal cardiac arrhythmias. In the present study, we combined mathematical modelling with information-rich dynamic clamp experiments to determine the regulation of action potential morphology in guinea pig ventricular myocytes. Parameter sensitivity analysis was used to predict how changes in ionic currents alter action potential duration, and these were tested experimentally using dynamic clamp, a technique that allows for multiple perturbations to be tested in each cell. Surprisingly, we found that a leading mathematical model, developed with traditional approaches, systematically underestimated experimental responses to dynamic clamp perturbations. We then re-parameterized the model using a genetic algorithm, which allowed us to estimate ionic current levels in each of the cells studied. This unbiased model adjustment consistently predicted an increase in the rapid delayed rectifier K + current and a drastic decrease in the slow delayed rectifier K + current, and this prediction was validated experimentally. Subsequent simulations with the adjusted model generated the clinically relevant prediction that the slow delayed rectifier is better able to stabilize the action potential and suppress pro-arrhythmic events than the rapid delayed rectifier. In summary, iterative coupling of

Dipyridamole Body Surface Potential Mapping: Noninvasive Differentiation of Syndrome X from Coronary Artery Disease

Czech Academy of Sciences Publication Activity Database

Boudík, F.; Anger, Z.; Aschermann, M.; Vojáček, J.; Tomečková, Marie

2002-01-01

Roč. 35, č. 3 (2002), s. 181-191 ISSN 0022-0736 R&D Projects: GA MZd IZ4038 Keywords : body surface potential mapping * dipyridamole * coronary artery disease * syndrome X Subject RIV: BD - Theory of Information Impact factor: 0.599, year: 2002

Middle-School Students' Map Construction: Understanding Complex Spatial Displays.

Science.gov (United States)

Bausmith, Jennifer Merriman; Leinhardt, Gaea

1998-01-01

Examines the map-making process of middle-school students to determine which actions influence their accuracy, how prior knowledge helps their map construction, and what lessons can be learned from map making. Indicates that instruction that focuses on recognition of interconnections between map elements can promote map reasoning skills. (DSK)

Atomic resolution electrostatic potential mapping of graphene sheets by off-axis electron holography

Energy Technology Data Exchange (ETDEWEB)

Cooper, David, E-mail: david.cooper@cea.fr [University Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054, Grenoble (France); Pan, Cheng-Ta; Haigh, Sarah [School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom)

2014-06-21

Off-axis electron holography has been performed at atomic resolution with the microscope operated at 80 kV to provide electrostatic potential maps from single, double, and triple layer graphene. These electron holograms have been reconstructed in order to obtain information about atomically resolved and mean inner potentials. We propose that off-axis electron holography can now be used to measure the electrical properties in a range of two-dimensional semiconductor materials and three dimensional devices comprising stacked layers of films to provide important information about their electrical properties.

Atomic resolution electrostatic potential mapping of graphene sheets by off-axis electron holography

International Nuclear Information System (INIS)

Cooper, David; Pan, Cheng-Ta; Haigh, Sarah

2014-01-01

Off-axis electron holography has been performed at atomic resolution with the microscope operated at 80 kV to provide electrostatic potential maps from single, double, and triple layer graphene. These electron holograms have been reconstructed in order to obtain information about atomically resolved and mean inner potentials. We propose that off-axis electron holography can now be used to measure the electrical properties in a range of two-dimensional semiconductor materials and three dimensional devices comprising stacked layers of films to provide important information about their electrical properties.

An Excel-based implementation of the spectral method of action potential alternans analysis.

Science.gov (United States)

Pearman, Charles M

2014-12-01

Action potential (AP) alternans has been well established as a mechanism of arrhythmogenesis and sudden cardiac death. Proper interpretation of AP alternans requires a robust method of alternans quantification. Traditional methods of alternans analysis neglect higher order periodicities that may have greater pro-arrhythmic potential than classical 2:1 alternans. The spectral method of alternans analysis, already widely used in the related study of microvolt T-wave alternans, has also been used to study AP alternans. Software to meet the specific needs of AP alternans analysis is not currently available in the public domain. An AP analysis tool is implemented here, written in Visual Basic for Applications and using Microsoft Excel as a shell. This performs a sophisticated analysis of alternans behavior allowing reliable distinction of alternans from random fluctuations, quantification of alternans magnitude, and identification of which phases of the AP are most affected. In addition, the spectral method has been adapted to allow detection and quantification of higher order regular oscillations. Analysis of action potential morphology is also performed. A simple user interface enables easy import, analysis, and export of collated results. © 2014 The Author. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

Investigating a Potential Auxin-Related Mode of Hormetic/Inhibitory Action of the Phytotoxin Parthenin.

Science.gov (United States)

Belz, Regina G

2016-01-01

Parthenin is a metabolite of Parthenium hysterophorus and is believed to contribute to the weed's invasiveness via allelopathy. Despite the potential of parthenin to suppress competitors, low doses stimulate plant growth. This biphasic action was hypothesized to be auxin-like and, therefore, an auxin-related mode of parthenin action was investigated using two approaches: joint action experiments with Lactuca sativa, and dose-response experiments with auxin/antiauxin-resistant Arabidopsis thaliana genotypes. The joint action approach comprised binary mixtures of subinhibitory doses of the auxin 3-indoleacetic acid (IAA) mixed with parthenin or one of three reference compounds [indole-3-butyric acid (IBA), 2,3,5-triiodobenzoic acid (TIBA), 2-(p-chlorophenoxy)-2-methylpropionic acid (PCIB)]. The reference compounds significantly interacted with IAA at all doses, but parthenin interacted only at low doses indicating that parthenin hormesis may be auxin-related, in contrast to its inhibitory action. The genetic approach investigated the response of four auxin/antiauxin-resistant mutants and a wildtype to parthenin or two reference compounds (IAA, PCIB). The responses of mutant plants to the reference compounds confirmed previous reports, but differed from the responses observed for parthenin. Parthenin stimulated and inhibited all mutants independent of resistance. This provided no indication for an auxin-related action of parthenin. Therefore, the hypothesis of an auxin-related inhibitory action of parthenin was rejected in two independent experimental approaches, while the hypothesis of an auxin-related stimulatory effect could not be rejected.

Passive language mapping combining real-time oscillation analysis with cortico-cortical evoked potentials for awake craniotomy.

Science.gov (United States)

Tamura, Yukie; Ogawa, Hiroshi; Kapeller, Christoph; Prueckl, Robert; Takeuchi, Fumiya; Anei, Ryogo; Ritaccio, Anthony; Guger, Christoph; Kamada, Kyousuke

2016-12-01

OBJECTIVE Electrocortical stimulation (ECS) is the gold standard for functional brain mapping; however, precise functional mapping is still difficult in patients with language deficits. High gamma activity (HGA) between 80 and 140 Hz on electrocorticography is assumed to reflect localized cortical processing, whereas the cortico-cortical evoked potential (CCEP) can reflect bidirectional responses evoked by monophasic pulse stimuli to the language cortices when there is no patient cooperation. The authors propose the use of "passive" mapping by combining HGA mapping and CCEP recording without active tasks during conscious resections of brain tumors. METHODS Five patients, each with an intraaxial tumor in their dominant hemisphere, underwent conscious resection of their lesion with passive mapping. The authors performed functional localization for the receptive language area, using real-time HGA mapping, by listening passively to linguistic sounds. Furthermore, single electrical pulses were delivered to the identified receptive temporal language area to detect CCEPs in the frontal lobe. All mapping results were validated by ECS, and the sensitivity and specificity were evaluated. RESULTS Linguistic HGA mapping quickly identified the language area in the temporal lobe. Electrical stimulation by linguistic HGA mapping to the identified temporal receptive language area evoked CCEPs on the frontal lobe. The combination of linguistic HGA and frontal CCEPs needed no patient cooperation or effort. In this small case series, the sensitivity and specificity were 93.8% and 89%, respectively. CONCLUSIONS The described technique allows for simple and quick functional brain mapping with higher sensitivity and specificity than ECS mapping. The authors believe that this could improve the reliability of functional brain mapping and facilitate rational and objective operations. Passive mapping also sheds light on the underlying physiological mechanisms of language in the human brain.

Mapping and Changing Informal Nurse Leadership Communication Pathways in a Health System

Directory of Open Access Journals (Sweden)

David C. Benton, PhD, RN, FRCN

2015-03-01

Conclusions: SNA is a useful tool in mapping existing networks and evaluating how these can be strengthened through the use of task orientated project work. This easy-to-use technique can provide useful insights and a means of targeting management action to improve communication pathways in a moderately large and complex nurse leadership group. Further clinical and academic potential uses of the technique are suggested.

Traditional Japanese medicines inhibit compound action potentials in the frog sciatic nerve.

Science.gov (United States)

Matsushita, Akitomo; Fujita, Tsugumi; Ohtsubo, Sena; Kumamoto, Eiichi

2016-02-03

Traditional Japanese (Kampo) medicines have a variety of clinical effects including pain alleviation, but evidence for a mechanism for their pain relief has not yet been elucidated fully. Considering that Kampo medicine contains many plant-derived chemicals having an ability to inhibit nerve action potential conduction, it is possible that this medicine inhibits nerve conduction. The purpose of the present study was to know how various Kampo medicines affect nerve conduction. We examined the effects of Kampo and crude medicines on compound action potentials (CAPs) recorded from the frog sciatic nerve by using the air-gap method. Daikenchuto, rikkosan, kikyoto, rikkunshito, shakuyakukanzoto and kakkonto concentration-dependently reduced the peak amplitude of the CAP. Among the Kampo medicines, daikenchuto was the most effective in inhibiting CAPs. Daikenchuto is composed of three kinds of crude medicine, Japanese pepper, processed ginger and ginseng radix. When the crude medicines were tested, Japanese pepper and processed ginger reduced CAP peak amplitudes, while ginseng radix hardly affected CAPs. Moreover, there was an interaction between the Japanese pepper and processed ginger activities in such that one medicine at low but not high concentrations increased the extent of the inhibition by the other one that was co-applied. Kampo medicines have an ability to inhibit nerve conduction. This action of daikenchuto is due to Japanese pepper and processed ginger but not ginseng radix, probably through an interaction between Japanese pepper and processed ginger in a manner dependent on their concentrations. Nerve conduction inhibition could contribute to at least a part of Kampo medicine's clinical effects such as pain alleviation. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Action potential generation requires a high sodium channel density in the axon initial segment

NARCIS (Netherlands)

Kole, Maarten H. P.; Ilschner, Susanne U.; Kampa, Björn M.; Williams, Stephen R.; Ruben, Peter C.; Stuart, Greg J.

2008-01-01

The axon initial segment ( AIS) is a specialized region in neurons where action potentials are initiated. It is commonly assumed that this process requires a high density of voltage-gated sodium ( Na(+)) channels. Paradoxically, the results of patch-clamp studies suggest that the Na(+) channel

Simulating the Epidemiological and Economic Impact of Paratuberculosis Control Actions in Dairy Cattle

Directory of Open Access Journals (Sweden)

Carsten Kirkeby

2016-10-01

Full Text Available We describe a new mechanistic bio-economic model for simulating the spread of Mycobacterium avium ssp. paratuberculosis (MAP within a dairy cattle herd. The model includes age-dependent susceptibility for infection; age-dependent sensitivity for detection; environmental MAP build-up in five separate areas of the farm; in utero infection; infection via colostrum and waste milk, and it allows for realistic culling (i.e. due to other diseases by including a ranking system. We calibrated the model using a unique dataset from Denmark, including 102 random farms with no control actions against spread of MAP. Likewise, four control actions recommended in the Danish MAP control program were implemented in the model based on reported management strategies in Danish dairy herds in a MAP control scheme. We tested the model parameterization in a sensitivity analysis. We show that a test-and-cull strategy is on average the most cost-effective solution to decrease the prevalence and increase the total net revenue on a farm with low hygiene, but not more profitable than no control strategy on a farm with average hygiene. Although it is possible to eradicate MAP from the farm by implementing all four control actions from the Danish MAP control program, it was not economically attractive since the expenses for the control actions outweigh the benefits. Furthermore, the three most popular control actions against the spread of MAP on the farm were found to be costly and inefficient in lowering the prevalence when used independently.

Potentiating action of propofol at GABAA receptors of retinal bipolar cells

DEFF Research Database (Denmark)

Yue, Lan; Xie, An; Bruzik, Karol S

2011-01-01

Purpose. Propofol (2,6-diisopropyl phenol), a widely used systemic anesthetic, is known to potentiate GABA(A) receptor activity in a number of CNS neurons and to produce changes in electroretinographically recorded responses of the retina. However, little is known about propofol's effects...... on specific retinal neurons. The authors investigated the action of propofol on GABA-elicited membrane current responses of retinal bipolar cells, which have both GABA(A) and GABA(C) receptors. Methods. Single, enzymatically dissociated bipolar cells obtained from rat retina were treated with propofol...... + propofol) led to a progressive increase in peak response amplitude and, at higher propofol concentrations, additional changes that included a prolonged time course of response recovery. Pre-exposure of the cell to perfusing propofol typically enhanced the rate of development of potentiation produced...

Melatonin potentiates the anticonvulsant action of phenobarbital in neonatal rats.

Science.gov (United States)

Forcelli, Patrick A; Soper, Colin; Duckles, Anne; Gale, Karen; Kondratyev, Alexei

2013-12-01

Phenobarbital is the most commonly utilized drug for neonatal seizures. However, questions regarding safety and efficacy of this drug make it particularly compelling to identify adjunct therapies that could boost therapeutic benefit. One potential adjunct therapy is melatonin. Melatonin is used clinically in neonatal and pediatric populations, and moreover, it exerts anticonvulsant actions in adult rats. However, it has not been previously evaluated for anticonvulsant effects in neonatal rats. Here, we tested the hypothesis that melatonin would exert anticonvulsant effects, either alone, or in combination with phenobarbital. Postnatal day (P)7 rats were treated with phenobarbital (0-40mg/kg) and/or melatonin (0-80mg/kg) prior to chemoconvulsant challenge with pentylenetetrazole (100mg/kg). We found that melatonin significantly potentiated the anticonvulsant efficacy of phenobarbital, but did not exert anticonvulsant effects on its own. These data provide additional evidence for the further examination of melatonin as an adjunct therapy in neonatal/pediatric epilepsy. Copyright © 2013 Elsevier B.V. All rights reserved.

Mapping wetland loss and restoration potential in Flanders (Belgium: an ecosystem service perspective

Directory of Open Access Journals (Sweden)

Kris Decleer

2016-12-01

Full Text Available With the case of Flanders (northern part of Belgium we present an integrated approach to calculate accurate losses of wetlands, potentials for restoration, and their ecosystem services supplies and illustrate how these insights can be used to evaluate and support policy making. Flanders lost about 75% of its wetland habitats in the past 50-60 years, with currently only 68,000 ha remaining, often in a more or less degraded state. For five different wetland categories (excluding open waters we calculated that restoration of lost wetland is still possible for an additional total area of about 147,000 ha, assuming that, with time and appropriate measures and techniques, the necessary biophysical and ecological conditions can more or less be restored or created. Wetland restoration opportunities were mapped according to an open and forested landscape scenario. Despite the fact that for 49,000 ha wetland restoration is justifiable by the actual presence of an appropriate spatial planning and/or protection status, the official Flemish nature policy only foresees 7,400 to 10,600 ha of additional wetland (open waters excluded by 2050. The benefits of a more ambitious wetland restoration action program are underpinned by an explorative and quantified analysis of ecosystem service supply for each of the two scenarios, showing that the strongly increased supply of several important regulating and cultural ecosystem services might outweigh the decrease of food production, especially if extensive farming on temporary wet soils remains possible. Finally, we discuss the challenges of wetland restoration policies for biodiversity conservation and climate change.

Changes in time and frequency related aspects of motor unit action potentials during fatigue

NARCIS (Netherlands)

Wallinga, W.; Bouwens, Jeroen S.; Baten, Christian T.M.

1996-01-01

During fatigue the shape of motor unit action potentials (MUAPs) change. Characteristics of the MUAPs described before concern several time related aspects. No attention has been given to the frequency spectrum changes of MUAPS. The median frequency of MUAPS has now been determined for motor units

The Influence of Glutamate on Axonal Compound Action Potential In Vitro.

Science.gov (United States)

Abouelela, Ahmed; Wieraszko, Andrzej

2016-01-01

Background  Our previous experiments demonstrated modulation of the amplitude of the axonal compound action potential (CAP) by electrical stimulation. To verify assumption that glutamate released from axons could be involved in this phenomenon, the modification of the axonal CAP induced by glutamate was investigated. Objectives  The major objective of this research is to verify the hypothesis that axonal activity would trigger the release of glutamate, which in turn would interact with specific axonal receptors modifying the amplitude of the action potential. Methods  Segments of the sciatic nerve were exposed to exogenous glutamate in vitro, and CAP was recorded before and after glutamate application. In some experiments, the release of radioactive glutamate analog from the sciatic nerve exposed to exogenous glutamate was also evaluated. Results  The glutamate-induced increase in CAP was blocked by different glutamate receptor antagonists. The effect of glutamate was not observed in Ca-free medium, and was blocked by antagonists of calcium channels. Exogenous glutamate, applied to the segments of sciatic nerve, induced the release of radioactive glutamate analog, demonstrating glutamate-induced glutamate release. Immunohistochemical examination revealed that axolemma contains components necessary for glutamatergic neurotransmission. Conclusion  The proteins of the axonal membrane can under the influence of electrical stimulation or exogenous glutamate change membrane permeability and ionic conductance, leading to a change in the amplitude of CAP. We suggest that increased axonal activity leads to the release of glutamate that results in changes in the amplitude of CAPs.

Mapping neuroplastic potential in brain-damaged patients.

Science.gov (United States)

Herbet, Guillaume; Maheu, Maxime; Costi, Emanuele; Lafargue, Gilles; Duffau, Hugues

2016-03-01

It is increasingly acknowledged that the brain is highly plastic. However, the anatomic factors governing the potential for neuroplasticity have hardly been investigated. To bridge this knowledge gap, we generated a probabilistic atlas of functional plasticity derived from both anatomic magnetic resonance imaging results and intraoperative mapping data on 231 patients having undergone surgery for diffuse, low-grade glioma. The atlas includes detailed level of confidence information and is supplemented with a series of comprehensive, connectivity-based cluster analyses. Our results show that cortical plasticity is generally high in the cortex (except in primary unimodal areas and in a small set of neural hubs) and rather low in connective tracts (especially associative and projection tracts). The atlas sheds new light on the topological organization of critical neural systems and may also be useful in predicting the likelihood of recovery (as a function of lesion topology) in various neuropathological conditions-a crucial factor in improving the care of brain-damaged patients. © The Author (2016). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Mapping of groundwater potential zones in the musi basin using remote sensing data and gis

NARCIS (Netherlands)

Ganapuram, Sreedhar; Vijaya Kumar, G.T.; Murali Krishna, I.V.; Kahya, Ercan; Demirel, M.C.

2009-01-01

The objective of this study is to explore the groundwater availability for agriculture in the Musi basin. Remote sensing data and geographic information system were used to locate potential zones for groundwater in the Musi basin. Various maps (i.e., base, hydrogeomorphological, geological,

Oxidative shift in tissue redox potential increases beat-to-beat variability of action potential duration.

Science.gov (United States)

Kistamás, Kornél; Hegyi, Bence; Váczi, Krisztina; Horváth, Balázs; Bányász, Tamás; Magyar, János; Szentandrássy, Norbert; Nánási, Péter P

2015-07-01

Profound changes in tissue redox potential occur in the heart under conditions of oxidative stress frequently associated with cardiac arrhythmias. Since beat-to-beat variability (short term variability, SV) of action potential duration (APD) is a good indicator of arrhythmia incidence, the aim of this work was to study the influence of redox changes on SV in isolated canine ventricular cardiomyocytes using a conventional microelectrode technique. The redox potential was shifted toward a reduced state using a reductive cocktail (containing dithiothreitol, glutathione, and ascorbic acid) while oxidative changes were initiated by superfusion with H2O2. Redox effects were evaluated as changes in "relative SV" determined by comparing SV changes with the concomitant APD changes. Exposure of myocytes to the reductive cocktail decreased SV significantly without any detectable effect on APD. Application of H2O2 increased both SV and APD, but the enhancement of SV was the greater, so relative SV increased. Longer exposure to H2O2 resulted in the development of early afterdepolarizations accompanied by tremendously increased SV. Pretreatment with the reductive cocktail prevented both elevation in relative SV and the development of afterdepolarizations. The results suggest that the increased beat-to-beat variability during an oxidative stress contributes to the generation of cardiac arrhythmias.

Radon potential mapping of the Tralee-Castleisland and Cavan areas (Ireland) based on airborne gamma-ray spectrometry and geology.

Science.gov (United States)

Appleton, J D; Doyle, E; Fenton, D; Organo, C

2011-06-01

The probability of homes in Ireland having high indoor radon concentrations is estimated on the basis of known in-house radon measurements averaged over 10 km × 10 km grid squares. The scope for using airborne gamma-ray spectrometer data for the Tralee-Castleisland area of county Kerry and county Cavan to predict the radon potential (RP) in two distinct areas of Ireland is evaluated in this study. Airborne data are compared statistically with in-house radon measurements in conjunction with geological and ground permeability data to establish linear regression models and produce radon potential maps. The best agreement between the percentage of dwellings exceeding the reference level (RL) for radon concentrations in Ireland (% > RL), estimated from indoor radon data, and modelled RP in the Tralee-Castleisland area is produced using models based on airborne gamma-ray spectrometry equivalent uranium (eU) and ground permeability data. Good agreement was obtained between the % > RL from indoor radon data and RP estimated from eU data in the Cavan area using terrain specific models. In both areas, RP maps derived from eU data are spatially more detailed than the published 10 km grid map. The results show the potential for using airborne radiometric data for producing RP maps.

Mapping the most significant computer hacking events to a temporal computer attack model

CSIR Research Space (South Africa)

Van Heerden, R

2012-09-01

Full Text Available of an impending net- work attack, and occur before any real damage has occurred. Popular reconnaissance actions include network mapping and scanning with tools such as Nmap and Nessus. Google and other search engines can also be used to identify potential weak.... ? Reconnaissance: Using well-known search engines to search for potential weak- nesses in the Windows operating system and Microsoft Outlook. ? Ramp-up: Writing the I-LOVE-YOU worm code. ? Damage: The spreading the I-LOVE-YOU worm via e-mail. It led...

Heteromeric Kv7.2/7.3 channels differentially regulate action potential initiation and conduction in neocortical myelinated axons.

Science.gov (United States)

Battefeld, Arne; Tran, Baouyen T; Gavrilis, Jason; Cooper, Edward C; Kole, Maarten H P

2014-03-05

Rapid energy-efficient signaling along vertebrate axons is achieved through intricate subcellular arrangements of voltage-gated ion channels and myelination. One recently appreciated example is the tight colocalization of K(v)7 potassium channels and voltage-gated sodium (Na(v)) channels in the axonal initial segment and nodes of Ranvier. The local biophysical properties of these K(v)7 channels and the functional impact of colocalization with Na(v) channels remain poorly understood. Here, we quantitatively examined K(v)7 channels in myelinated axons of rat neocortical pyramidal neurons using high-resolution confocal imaging and patch-clamp recording. K(v)7.2 and 7.3 immunoreactivity steeply increased within the distal two-thirds of the axon initial segment and was mirrored by the conductance density estimates, which increased from ~12 (proximal) to 150 pS μm(-2) (distal). The axonal initial segment and nodal M-currents were similar in voltage dependence and kinetics, carried by K(v)7.2/7.3 heterotetramers, 4% activated at the resting membrane potential and rapidly activated with single-exponential time constants (~15 ms at 28 mV). Experiments and computational modeling showed that while somatodendritic K(v)7 channels are strongly activated by the backpropagating action potential to attenuate the afterdepolarization and repetitive firing, axonal K(v)7 channels are minimally recruited by the forward-propagating action potential. Instead, in nodal domains K(v)7.2/7.3 channels were found to increase Na(v) channel availability and action potential amplitude by stabilizing the resting membrane potential. Thus, K(v)7 clustering near axonal Na(v) channels serves specific and context-dependent roles, both restraining initiation and enhancing conduction of the action potential.

Recording single neurons' action potentials from freely moving pigeons across three stages of learning.

Science.gov (United States)

Starosta, Sarah; Stüttgen, Maik C; Güntürkün, Onur

2014-06-02

While the subject of learning has attracted immense interest from both behavioral and neural scientists, only relatively few investigators have observed single-neuron activity while animals are acquiring an operantly conditioned response, or when that response is extinguished. But even in these cases, observation periods usually encompass only a single stage of learning, i.e. acquisition or extinction, but not both (exceptions include protocols employing reversal learning; see Bingman et al.(1) for an example). However, acquisition and extinction entail different learning mechanisms and are therefore expected to be accompanied by different types and/or loci of neural plasticity. Accordingly, we developed a behavioral paradigm which institutes three stages of learning in a single behavioral session and which is well suited for the simultaneous recording of single neurons' action potentials. Animals are trained on a single-interval forced choice task which requires mapping each of two possible choice responses to the presentation of different novel visual stimuli (acquisition). After having reached a predefined performance criterion, one of the two choice responses is no longer reinforced (extinction). Following a certain decrement in performance level, correct responses are reinforced again (reacquisition). By using a new set of stimuli in every session, animals can undergo the acquisition-extinction-reacquisition process repeatedly. Because all three stages of learning occur in a single behavioral session, the paradigm is ideal for the simultaneous observation of the spiking output of multiple single neurons. We use pigeons as model systems, but the task can easily be adapted to any other species capable of conditioned discrimination learning.

Development of potential map for landslides by comparing instability indices of various time periods

Science.gov (United States)

Chiang, Jie-Lun; Tian, Yu-Qing; Chen, Yie-Ruey; Tsai, Kuang-Jung

2017-04-01

In recent years, extreme rainfall events occur frequently and induced serious landslides and debris flow disasters in Taiwan. The instability indices will differ when using landslide maps of different time periods. We analyzed the landslide records during the period year, 2008 2012, the landslide area contributed 0.42% 2.94% of the total watershed area, the 2.94% was caused by the typhoon Morakot in August, 2009, which brought massive rainfall in which the cumulative maximum rainfall was up to 2900 mm. We analyzed the instability factors including elevation, slope, aspect, soil, and geology. And comparing the instability indices by using individual landslide map of 2008 2012, the landslide maps of the union of the five years, and interaction of the five years. The landslide area from union of the five years contributed 3.71%,the landslide area from interaction of the five years contributed 0.14%. In this study, Kriging was used to establish the susceptibility map in selected watershed. From interaction of the five years, we found the instability index above 4.3 can correspond to those landslide records. The potential landslide area of the selected watershed, where collapses occur more likely, belongs to high level and medium-high level; the area is 13.43% and 3.04% respectively.

Collective action and its interpreters

Directory of Open Access Journals (Sweden)

João Alfredo Costa de Campos Melo Júnior

2007-12-01

Full Text Available This article intention is to give the theorical and intellectual map production regarding collective actions. For such, we will analyze the propositions of five thinkers who have work for the better understanding of this question. We will discuss the contributions of the Chicago School, especially psic-sociology, and Herbert Blumer symbolic interactionism; the classical Marxists approaches on collective actions; Claus Offe and the Marxist point of view on the new models of collective actions; Charles Tilly and his social-historic perspective analysis about social movements; and finally Mancur Olson and collective action from a rational perspective. What we intend is to present comparatively the theorical and practical similarities and exclusions of these contemporary authors who contribute with collective actions today.

Comment on "Penetration of Action Potentials During Collision in the Median and Lateral Giant Axons of Invertebrates"

DEFF Research Database (Denmark)

Berg, Rune W.; Stauning, Marius Tving; Sorensen, Jakob Balslev

2017-01-01

The action potential (AP) is an electrical impulse elicited by depolarization of the neuronal membrane from the resting membrane potential (around − 70 mV). It propagates along the axon, allowing for rapid and distant communication. Recently, it was claimed that two APs traveling in opposite...

Spatial and frequency domain ring source models for the single muscle fiber action potential

DEFF Research Database (Denmark)

Henneberg, Kaj-åge; R., Plonsey

1994-01-01

In the paper, single-fibre models for the extracellular action potential are developed that will allow the potential to the evaluated at an arbitrary field point in the extracellular space. Fourier-domain models are restricted in that they evaluate potentials at equidistant points along a line...... parallel to the fibre axis. Consequently, they cannot easily evaluate the potential at the boundary nodes of a boundary-element electrode model. The Fourier-domain models employ axial-symmetric ring source models, and thereby provide higher accuracy that the line source model, where the source is lumped...... including anisotropy show that the spatial models require extreme care in the integration procedure owing to the singularity in the weighting functions. With adequate sampling, the spatial models can evaluate extracellular potentials with high accuracy....

Potential of EnMAP spaceborne imaging spectroscopy for the prediction of common surface soil properties and expected accuracy

Science.gov (United States)

Chabrillat, Sabine; Foerster, Saskia; Steinberg, Andreas; Stevens, Antoine; Segl, Karl

2016-04-01

There is a renewed awareness of the finite nature of the world's soil resources, growing concern about soil security, and significant uncertainties about the carrying capacity of the planet. As a consequence, soil scientists are being challenged to provide regular assessments of soil conditions from local through to global scales. However, only a few countries have the necessary survey and monitoring programs to meet these new needs and existing global data sets are out-of-date. A particular issue is the clear demand for a new area-wide regional to global coverage with accurate, up-to-date, and spatially referenced soil information as expressed by the modeling scientific community, farmers and land users, and policy and decision makers. Soil spectroscopy from remote sensing observations based on studies from the laboratory scale to the airborne scale has been shown to be a proven method for the quantitative prediction of key soil surface properties in local areas for exposed soils in appropriate surface conditions such as low vegetation cover and low water content. With the upcoming launch of the next generation of hyperspectral satellite sensors in the next 3 to 5 years (EnMAP, HISUI, PRISMA, SHALOM), a great potential for the global mapping and monitoring of soil properties is appearing. Nevertheless, the capabilities to extend the soil properties current spectral modeling from local to regional scales are still to be demonstrated using robust methods. In particular, three central questions are at the forefront of research nowadays: a) methodological developments toward improved algorithms and operational tools for the extraction of soil properties, b) up scaling from the laboratory into space domain, and c) demonstration of the potential of upcoming satellite systems and expected accuracy of soil maps. In this study, airborne imaging spectroscopy data from several test sites are used to simulate EnMAP satellite images at 30 m scale. Then, different soil

The real-time link between person perception and action: brain potential evidence for dynamic continuity.

Science.gov (United States)

Freeman, Jonathan B; Ambady, Nalini; Midgley, Katherine J; Holcomb, Phillip J

2011-01-01

Using event-related potentials, we investigated how the brain extracts information from another's face and translates it into relevant action in real time. In Study 1, participants made between-hand sex categorizations of sex-typical and sex-atypical faces. Sex-atypical faces evoked negativity between 250 and 550 ms (N300/N400 effects), reflecting the integration of accumulating sex-category knowledge into a coherent sex-category interpretation. Additionally, the lateralized readiness potential revealed that the motor cortex began preparing for a correct hand response while social category knowledge was still gradually evolving in parallel. In Study 2, participants made between-hand eye-color categorizations as part of go/no-go trials that were contingent on a target's sex. On no-go trials, although the hand did not actually move, information about eye color partially prepared the motor cortex to move the hand before perception of sex had finalized. Together, these findings demonstrate the dynamic continuity between person perception and action, such that ongoing results from face processing are immediately and continuously cascaded into the motor system over time. The preparation of action begins based on tentative perceptions of another's face before perceivers have finished interpreting what they just saw. © 2010 Psychology Press, an imprint of the Taylor & Francis Group, an Informa business

A mapping of drug space from the viewpoint of small molecule metabolism.

Directory of Open Access Journals (Sweden)

James Corey Adams

2009-08-01

Full Text Available Small molecule drugs target many core metabolic enzymes in humans and pathogens, often mimicking endogenous ligands. The effects may be therapeutic or toxic, but are frequently unexpected. A large-scale mapping of the intersection between drugs and metabolism is needed to better guide drug discovery. To map the intersection between drugs and metabolism, we have grouped drugs and metabolites by their associated targets and enzymes using ligand-based set signatures created to quantify their degree of similarity in chemical space. The results reveal the chemical space that has been explored for metabolic targets, where successful drugs have been found, and what novel territory remains. To aid other researchers in their drug discovery efforts, we have created an online resource of interactive maps linking drugs to metabolism. These maps predict the "effect space" comprising likely target enzymes for each of the 246 MDDR drug classes in humans. The online resource also provides species-specific interactive drug-metabolism maps for each of the 385 model organisms and pathogens in the BioCyc database collection. Chemical similarity links between drugs and metabolites predict potential toxicity, suggest routes of metabolism, and reveal drug polypharmacology. The metabolic maps enable interactive navigation of the vast biological data on potential metabolic drug targets and the drug chemistry currently available to prosecute those targets. Thus, this work provides a large-scale approach to ligand-based prediction of drug action in small molecule metabolism.

A mapping of drug space from the viewpoint of small molecule metabolism.

Science.gov (United States)

Adams, James Corey; Keiser, Michael J; Basuino, Li; Chambers, Henry F; Lee, Deok-Sun; Wiest, Olaf G; Babbitt, Patricia C

2009-08-01

Small molecule drugs target many core metabolic enzymes in humans and pathogens, often mimicking endogenous ligands. The effects may be therapeutic or toxic, but are frequently unexpected. A large-scale mapping of the intersection between drugs and metabolism is needed to better guide drug discovery. To map the intersection between drugs and metabolism, we have grouped drugs and metabolites by their associated targets and enzymes using ligand-based set signatures created to quantify their degree of similarity in chemical space. The results reveal the chemical space that has been explored for metabolic targets, where successful drugs have been found, and what novel territory remains. To aid other researchers in their drug discovery efforts, we have created an online resource of interactive maps linking drugs to metabolism. These maps predict the "effect space" comprising likely target enzymes for each of the 246 MDDR drug classes in humans. The online resource also provides species-specific interactive drug-metabolism maps for each of the 385 model organisms and pathogens in the BioCyc database collection. Chemical similarity links between drugs and metabolites predict potential toxicity, suggest routes of metabolism, and reveal drug polypharmacology. The metabolic maps enable interactive navigation of the vast biological data on potential metabolic drug targets and the drug chemistry currently available to prosecute those targets. Thus, this work provides a large-scale approach to ligand-based prediction of drug action in small molecule metabolism.

A Fire Severity Mapping System (FSMS) for real-time management applications and long term planning: Developing a map of the landscape potential for severe fire in the western United States

Science.gov (United States)

Gregory K. Dillon; Zachary A. Holden; Penny Morgan; Bob Keane

2009-01-01

The Fire Severity Mapping System project is geared toward providing fire managers across the western United States with critical information for dealing with and planning for the ecological effects of wildfire at multiple levels of thematic, spatial, and temporal detail. For this project, we are developing a comprehensive, west-wide map of the landscape potential for...

Morphological Characterization of the Action Potential Initiation Segment in GnRH Neuron Dendrites and Axons of Male Mice.

Science.gov (United States)

Herde, Michel K; Herbison, Allan E

2015-11-01

GnRH neurons are the final output neurons of the hypothalamic network controlling fertility in mammals. In the present study, we used ankyrin G immunohistochemistry and neurobiotin filling of live GnRH neurons in brain slices from GnRH-green fluorescent protein transgenic male mice to examine in detail the location of action potential initiation in GnRH neurons with somata residing at different locations in the basal forebrain. We found that the vast majority of GnRH neurons are bipolar in morphology, elaborating a thick (primary) and thinner (secondary) dendrite from opposite poles of the soma. In addition, an axon-like process arising predominantly from a proximal dendrite was observed in a subpopulation of GnRH neurons. Ankyrin G immunohistochemistry revealed the presence of a single action potential initiation zone ∼27 μm in length primarily in the secondary dendrite of GnRH neurons and located 30 to 140 μm distant from the cell soma, depending on the type of process and location of the cell body. In addition to dendrites, the GnRH neurons with cell bodies located close to hypothalamic circumventricular organs often elaborated ankyrin G-positive axon-like structures. Almost all GnRH neurons (>90%) had their action potential initiation site in a process that initially, or ultimately after a hairpin loop, was coursing in the direction of the median eminence. These studies indicate that action potentials are initiated in different dendritic and axonal compartments of the GnRH neuron in a manner that is dependent partly on the neuroanatomical location of the cell body.

Southern Salish Sea Habitat Map Series: Admiralty Inlet

Science.gov (United States)

Cochrane, Guy R.; Dethier, Megan N.; Hodson, Timothy O.; Kull, Kristine K.; Golden, Nadine E.; Ritchie, Andrew C.; Moegling, Crescent; Pacunski, Robert E.; Cochrane, Guy R.

2015-01-01

In 2010 the Environmental Protection Agency, Region 10 initiated the Puget Sound Scientific Studies and Technical Investigations Assistance Program, designed to support research in support of implementing the Puget Sound Action Agenda. The Action Agenda was created in response to Puget Sound having been designated as one of 28 estuaries of national significance under section 320 of the U.S. Clean Water Act, and its overall goal is to restore the Puget Sound Estuary's environment by 2020. The Southern Salish Sea Mapping Project was funded by the Assistance Program request for proposals process, which also supports a large number of coastal-zone- and ocean-management issues. The issues include the recommendations of the Marine Protected Areas Work Group to the Washington State Legislature (Van Cleve and others, 2009), which endorses a Puget Sound and coast-wide marine conservation needs assessment, gap analysis of existing Marine Protected Areas (MPA) and recommendations for action. This publication is the first of four U.S. Geological Survey Scientific Investigation Maps that make up the Southern Salish Sea Mapping Project. The remaining three map blocks to be published in the future, located south of Admiralty Inlet, are shown in figure 1.

Maps for the future.

Directory of Open Access Journals (Sweden)

Cristina D’Alessandro-Scarpari

2005-05-01

Full Text Available Geographers’ relations with maps have a long story of attraction and repulsion. The map has always fascinated Geographers (even before the institutionalization of the discipline as a powerful tool, able to demarcate territories, to produce different visions of them and to transform them by the actions they may cause or influence. Sometimes for strategic reasons Geographers have also denigrated cartography as a secondary and technical form of knowledge, a tool merely for understanding and ...

Alteration zone mapping for detecting potential mineralized areas in Kaladawan of north altyn tagh using ASTER data

International Nuclear Information System (INIS)

Yong-gui, Zhou; Bai-lin, Chen; Xing-tong, Chen; Zheng-le, Chen

2014-01-01

The Kaladawan area has been found developing intense hydrothermal altered rocks associated with mineralized area such as Kaladaban Pb-Zn deposit, A-bei Ag-Pb depositduring earlier geological investigations.Yet the sparse vegetation cover and excellent bedrock exposure make it a suitable place for the use of remote sensing methods for lithological mapping. ASTER data has been used in this study to identify alteration zones, and then to detect potential mineralized areas. Band ratio and PCA procedures were applied based on the analysis of spectral properties of typical alteration minerals. Band 4/2 and mineralogic indices proposed by Ninomiya were designed to map the distribution of Fe-oxides and alteration zones. Selected bands combinations were transformed in a PCA procedure to map the Al-OH, Mg-OH, CO 3 2− and Fe-oxides altered minerals. The analysis focused on the spatial distribution of hydrothermal altered minerals. Band ratio result images including both Fe-oxides and mineralogic indices show high-level similarity with the PCA transform procedure. They both show intense hydrothermal alteration zone in Kaladaban,west Kaladawan and A-bei area. Hence, these areas are considered to have potential for further mineralogic exploration. The results were validated by field work in the Kaladaban and west Kaladawan area,indicating that this method can be a useful tool for detecting potential mineralization area in Kaladawan and similar areas elsewhere

Using a binary logistic regression method and GIS for evaluating and mapping the groundwater spring potential in the Sultan Mountains (Aksehir, Turkey)

Science.gov (United States)

Ozdemir, Adnan

2011-07-01

SummaryThe purpose of this study is to produce a groundwater spring potential map of the Sultan Mountains in central Turkey, based on a logistic regression method within a Geographic Information System (GIS) environment. Using field surveys, the locations of the springs (440 springs) were determined in the study area. In this study, 17 spring-related factors were used in the analysis: geology, relative permeability, land use/land cover, precipitation, elevation, slope, aspect, total curvature, plan curvature, profile curvature, wetness index, stream power index, sediment transport capacity index, distance to drainage, distance to fault, drainage density, and fault density map. The coefficients of the predictor variables were estimated using binary logistic regression analysis and were used to calculate the groundwater spring potential for the entire study area. The accuracy of the final spring potential map was evaluated based on the observed springs. The accuracy of the model was evaluated by calculating the relative operating characteristics. The area value of the relative operating characteristic curve model was found to be 0.82. These results indicate that the model is a good estimator of the spring potential in the study area. The spring potential map shows that the areas of very low, low, moderate and high groundwater spring potential classes are 105.586 km 2 (28.99%), 74.271 km 2 (19.906%), 101.203 km 2 (27.14%), and 90.05 km 2 (24.671%), respectively. The interpretations of the potential map showed that stream power index, relative permeability of lithologies, geology, elevation, aspect, wetness index, plan curvature, and drainage density play major roles in spring occurrence and distribution in the Sultan Mountains. The logistic regression approach has not yet been used to delineate groundwater potential zones. In this study, the logistic regression method was used to locate potential zones for groundwater springs in the Sultan Mountains. The evolved model

Risk-based fault detection using Self-Organizing Map

International Nuclear Information System (INIS)

Yu, Hongyang; Khan, Faisal; Garaniya, Vikram

2015-01-01

The complexity of modern systems is increasing rapidly and the dominating relationships among system variables have become highly non-linear. This results in difficulty in the identification of a system's operating states. In turn, this difficulty affects the sensitivity of fault detection and imposes a challenge on ensuring the safety of operation. In recent years, Self-Organizing Maps has gained popularity in system monitoring as a robust non-linear dimensionality reduction tool. Self-Organizing Map is able to capture non-linear variations of the system. Therefore, it is sensitive to the change of a system's states leading to early detection of fault. In this paper, a new approach based on Self-Organizing Map is proposed to detect and assess the risk of fault. In addition, probabilistic analysis is applied to characterize the risk of fault into different levels according to the hazard potential to enable a refined monitoring of the system. The proposed approach is applied on two experimental systems. The results from both systems have shown high sensitivity of the proposed approach in detecting and identifying the root cause of faults. The refined monitoring facilitates the determination of the risk of fault and early deployment of remedial actions and safety measures to minimize the potential impact of fault. - Highlights: • A new approach based on Self-Organizing Map is proposed to detect faults. • Integration of fault detection with risk assessment methodology. • Fault risk characterization into different levels to enable focused system monitoring

A Method to Analyze the Potential of Optical Remote Sensing for Benthic Habitat Mapping

Directory of Open Access Journals (Sweden)

Rodrigo A. Garcia

2015-10-01

Full Text Available Quantifying the number and type of benthic classes that are able to be spectrally identified in shallow water remote sensing is important in understanding its potential for habitat mapping. Factors that impact the effectiveness of shallow water habitat mapping include water column turbidity, depth, sensor and environmental noise, spectral resolution of the sensor and spectral variability of the benthic classes. In this paper, we present a simple hierarchical clustering method coupled with a shallow water forward model to generate water-column specific spectral libraries. This technique requires no prior decision on the number of classes to output: the resultant classes are optically separable above the spectral noise introduced by the sensor, image based radiometric corrections, the benthos’ natural spectral variability and the attenuating properties of a variable water column at depth. The modeling reveals the effect reducing the spectral resolution has on the number and type of classes that are optically distinct. We illustrate the potential of this clustering algorithm in an analysis of the conditions, including clustering accuracy, sensor spectral resolution and water column optical properties and depth that enabled the spectral distinction of the seagrass Amphibolis antartica from benthic algae.

Microelectrode array measurement of potassium ion channel remodeling on the field action potential duration in rapid atrial pacing rabbits model.

Science.gov (United States)

Sun, Juan; Yan, Huang; Wugeti, Najina; Guo, Yujun; Zhang, Ling; Ma, Mei; Guo, Xingui; Jiao, Changan; Xu, Wenli; Li, Tianqi

2015-01-01

Atrial fibrillation (AF) arises from abnormalities in atrial structure and electrical activity. Microelectrode arrays (MEA) is a real-time, nondestructive measurement of the resting and action potential signal, from myocardial cells, to the peripheral circuit of electrophysiological activity. This study examined the field action potential duration (fAPD) of the right atrial appendage (RAA) by MEA in rapid atrial pacing (RAP) in the right atrium of rabbits. In addition, this study also investigated the effect of potassium ion channel blockers on fAPD. 40 New Zealand white rabbits of either sex were randomly divided into 3 groups: 1) the control, 2) potassium ion channel blocker (TEA, 4-Ap and BaCl2), and 3) amiodarone groups. The hearts were quickly removed and right atrial appendage sectioned (slice thickness 500 μm). Each slice was perfused with Tyrode's solution and continuously stimulated for 30 minutes. Sections from the control group were superfused with Tyrode's solution for 10 minutes, while the blocker groups and amiodarone were both treated with their respective compounds for 10 minutes each. The fAPD of RAA and action field action potential morphology were measured using MEA. In non-pace (control) groups, fAPD was 188.33 ± 18.29 ms after Tyrode's solution superfusion, and 173.91 ± 6.83 ms after RAP. In pace/potassium ion channel groups, TEA and BaCl2 superfusion prolonged atrial field action potential (fAPD) (control vs blocker: 176.67 ± 8.66 ms vs 196.11 ± 10.76 ms, 182.22 ± 12.87 ms vs 191.11 ± 13.09 ms with TEA and BaCl2 superfusion, respectively, P action potential in animal heart slices. After superfusing potassium ion channel blockers, fAPD was prolonged. These results suggest that Ito, IKur and IK1 remodel and mediate RAP-induced atrial electrical remodeling. Amiodarone alter potassium ion channel activity (Ito, IKur, IK1 and IKs), shortening fAPD.

Geohazard reconnaissance mapping for potential rock boulder fall using low altitude UAV photogrammetry

Science.gov (United States)

Sharan Kumar, N.; Ashraf Mohamad Ismail, Mohd; Sukor, Nur Sabahiah Abdul; Cheang, William

2018-05-01

This paper discusses potential applications of unmanned aerial vehicles (UAVs) for evaluation of risk immediately with photos and 3-dimensional digital element. Aerial photography using UAV ready to give a powerful technique for potential rock boulder fall recognition. High-resolution outputs from this method give the chance to evaluate the site for potential rock boulder falls spatially. The utilization of UAV to capture the aerial photos is a quick, reliable, and cost-effective technique contrasted with terrestrial laser scanning method. Reconnaissance of potential rock boulder susceptible to fall is very crucial during the geotechnical investigation. This process is essential in the view of the rock fall hazards nearby site before the beginning of any preliminary work. Photogrammetric applications have empowered the automated way to deal with identification of rock boulder susceptible to fall by recognizing the location, size, and position. A developing examination of the utilization of digital photogrammetry gives numerous many benefits for civil engineering application. These advancements have made important contributions to our capabilities to create the geohazard map on potential rock boulder fall.

Fuzzy logic-based assessment for mapping potential infiltration areas in low-gradient watersheds.

Science.gov (United States)

Quiroz Londoño, Orlando Mauricio; Romanelli, Asunción; Lima, María Lourdes; Massone, Héctor Enrique; Martínez, Daniel Emilio

2016-07-01

This paper gives an account of the design a logic-based approach for identifying potential infiltration areas in low-gradient watersheds based on remote sensing data. This methodological framework is applied in a sector of the Pampa Plain, Argentina, which has high level of agricultural activities and large demands for groundwater supplies. Potential infiltration sites are assessed as a function of two primary topics: hydrologic and soil conditions. This model shows the state of each evaluated subwatershed respecting to its potential contribution to infiltration mainly based on easily measurable and commonly used parameters: drainage density, geomorphologic units, soil media, land-cover, slope and aspect (slope orientation). Mapped outputs from the logic model displayed 42% very low-low, 16% moderate, 41% high-very high contribution to potential infiltration in the whole watershed. Subwatersheds in the upper and lower section were identified as areas with high to very high potential infiltration according to the following media features: low drainage density (drainage plain and, dunes and beaches. Copyright © 2016 Elsevier Ltd. All rights reserved.

On the Classical and Quantum Momentum Map

DEFF Research Database (Denmark)

Esposito, Chiara

In this thesis we study the classical and quantum momentum maps and the theory of reduction. We focus on the notion of momentum map in Poisson geometry and we discuss the classification of the momentum map in this framework. Furthermore, we describe the so-called Poisson Reduction, a technique...... that allows us to reduce the dimension of a manifold in presence of symmetries implemented by Poisson actions. Using techniques of deformation quantization and quantum groups, we introduce the quantum momentum map as a deformation of the classical momentum map, constructed in such a way that it factorizes...

The use of mapped geology as a predictor of radon potential in Norway.

Science.gov (United States)

Watson, Robin J; Smethurst, Mark A; Ganerød, Guri V; Finne, Ingvild; Rudjord, Anne Liv

2017-01-01

Radon exposure is considered to cause several hundred fatalities from lung-cancer each year in Norway. A national map identifying areas which are likely to be exposed to elevated radon concentrations would be a useful tool for decision-making authorities, and would be particularly important in areas where only few indoor radon measurements exist. An earlier Norwegian study (Smethurst et al. 2008) produced radon hazard maps by examining the relationship between airborne gamma-ray spectrometry, bedrock and drift geology, and indoor radon. The study was limited to the Oslo region where substantial indoor radon and airborne equivalent uranium datasets were available, and did not attempt to test the statistical significance of relationships, or to quantify the confidence of its predictions. While it can be anticipated that airborne measurements may have useful predictive power for indoor radon, airborne measurement coverage in Norway is at present sparse; to provide national coverage of radon hazard estimates, a good understanding of the relationship between geology and indoor radon is therefore important. In this work we use a new enlarged (n = 34,563) form of the indoor radon dataset with national coverage, and we use it to examine the relationship between geology and indoor radon concentrations. We use this relationship to characterise geological classes by their radon potential, and we produce a national radon hazard map which includes confidence limits on the likelihood of areas having elevated radon concentrations, and which covers the whole of mainland Norway, even areas where little or no indoor radon data are available. We find that bedrock and drift geology classes can account for around 40% of the total observed variation in radon potential. We test geology-based predictions of RP (radon potential) against locally-derived estimates of RP, and produce classification matrices with kappa values in the range 0.37-0.56. Our classifier has high predictive value

Exercise body surface potential mapping in single and multiple coronary artery disease

International Nuclear Information System (INIS)

Montague, T.J.; Witkowski, F.X.; Miller, R.M.; Johnstone, D.E.; MacKenzie, R.B.; Spencer, C.A.; Horacek, B.M.

1990-01-01

Body surface ST integral maps were recorded in 36 coronary artery disease (CAD) patients at: rest; peak, angina-limited exercise; and, 1 and 5 min of recovery. They were compared to maps of 15 CAD patients who exercised to fatigue, without angina, and eight normal subjects. Peak exercise heart rates were similar (NS) in all groups. With exercise angina, patients with two and three vessel CAD had significantly (p less than 0.05) greater decrease in the body surface sum of ST integral values than patients with single vessel CAD. CAD patients with exercise fatigue, in the absence of angina, had decreased ST integrals similar (NS) to patients with single vessel CAD who manifested angina and the normal control subjects. There was, however, considerable overlap among individuals; some patients with single vessel CAD had as much exercise ST integral decrease as patients with three vessel CAD. All CAD patients had persistent ST integral decreases at 5 min of recovery and there was a direct correlation of the recovery and peak exercise ST changes. Exercise ST changes correlated, as well, with quantitative CAD angiographic scores, but not with thallium perfusion scores. These data suggest exercise ST integral body surface mapping allows quantitation of myocardium at ischemic risk in patients with CAD, irrespective of the presence or absence of ischemic symptoms during exercise. A major potential application of this technique is selection of CAD therapy guided by quantitative assessment of ischemic myocardial risk

Using a concept map as a tool for strategic planning: The Healthy Brain Initiative.

Science.gov (United States)

Anderson, Lynda A; Day, Kristine L; Vandenberg, Anna E

2011-09-01

Concept mapping is a tool to assist in strategic planning that allows planners to work through a sequence of phases to produce a conceptual framework. Although several studies describe how concept mapping is applied to various public health problems, the flexibility of the methods used in each phase of the process is often overlooked. If practitioners were more aware of the flexibility, more public health endeavors could benefit from using concept mapping as a tool for strategic planning. The objective of this article is to describe how the 6 concept-mapping phases originally outlined by William Trochim guided our strategic planning process and how we adjusted the specific methods in the first 2 phases to meet the specialized needs and requirements to create The Healthy Brain Initiative: A National Public Health Road Map to Maintaining Cognitive Health. In the first stage (phases 1 and 2 of concept mapping), we formed a steering committee, convened 4 work groups over a period of 3 months, and generated an initial set of 42 action items grounded in science. In the second stage (phases 3 and 4), we engaged stakeholders in sorting and rating the action items and constructed a series of concept maps. In the third and final stage (phases 5 and 6), we examined and refined the action items and generated a final concept map consisting of 44 action items. We then selected the top 10 action items, and in 2007, we published The Healthy Brain Initiative: A National Public Health Road Map to Maintaining Cognitive Health, which represents the strategic plan for The Healthy Brain Initiative.

A comparative assessment of GIS-based data mining models and a novel ensemble model in groundwater well potential mapping

Science.gov (United States)

Naghibi, Seyed Amir; Moghaddam, Davood Davoodi; Kalantar, Bahareh; Pradhan, Biswajeet; Kisi, Ozgur

2017-05-01

In recent years, application of ensemble models has been increased tremendously in various types of natural hazard assessment such as landslides and floods. However, application of this kind of robust models in groundwater potential mapping is relatively new. This study applied four data mining algorithms including AdaBoost, Bagging, generalized additive model (GAM), and Naive Bayes (NB) models to map groundwater potential. Then, a novel frequency ratio data mining ensemble model (FREM) was introduced and evaluated. For this purpose, eleven groundwater conditioning factors (GCFs), including altitude, slope aspect, slope angle, plan curvature, stream power index (SPI), river density, distance from rivers, topographic wetness index (TWI), land use, normalized difference vegetation index (NDVI), and lithology were mapped. About 281 well locations with high potential were selected. Wells were randomly partitioned into two classes for training the models (70% or 197) and validating them (30% or 84). AdaBoost, Bagging, GAM, and NB algorithms were employed to get groundwater potential maps (GPMs). The GPMs were categorized into potential classes using natural break method of classification scheme. In the next stage, frequency ratio (FR) value was calculated for the output of the four aforementioned models and were summed, and finally a GPM was produced using FREM. For validating the models, area under receiver operating characteristics (ROC) curve was calculated. The ROC curve for prediction dataset was 94.8, 93.5, 92.6, 92.0, and 84.4% for FREM, Bagging, AdaBoost, GAM, and NB models, respectively. The results indicated that FREM had the best performance among all the models. The better performance of the FREM model could be related to reduction of over fitting and possible errors. Other models such as AdaBoost, Bagging, GAM, and NB also produced acceptable performance in groundwater modelling. The GPMs produced in the current study may facilitate groundwater exploitation

[Effects of 2-(p-dimethylaminostyryl) pyridine methycholide (DSPM-Ci) on ECG, left atrium contractivity and on papillary muscle action potentials].

Science.gov (United States)

Jiang, X Y; Zhou, C M; Li, D M; Zhang, K J

1996-01-01

The effects of DSPM-Cl on ECG in rats, on the dose-effect curve in guinea pig left atria and on the fast action potential (AP), high-K+ depolarized slow action potential (SAP) in guinea pigs papillary muscle were examined electrophysiologically. DSPM-Cl (2 mg.kg-1) showed significant nagative frequency, negative conductivity effect, and prolonged the PP and PR interval. DSPM-CI (30-50 mumol.L-1) was shown to inhibit left atria contractility and shift the concentration-response curve of Iso and CaCl2 to the right with PD2' values of 4.60 and 4.13, respectively. In addition, DSPM-Cl was found to prolong the duration of action potential 90 (APD90) and effective refractory period (ERP), and decrease the maximal upstroke velocity (Vmax) in K(+)-depolarized guinea pigs papillary muscles. The results suggest that, like verpamil, DSPM-Cl might be a calcium antagonist.

The Transformative Potential of Action Research and ICT in the Second Language (L2) Classroom

Science.gov (United States)

Farren, Margaret; Crotty, Yvonne; Kilboy, Laura

2015-01-01

This study shows the transformative potential of action research and information and communications technology (ICT) in the second language (L2) classroom. Two enquiries from teacher-researchers are detailed in the article. Their engagement in a collaborative professional development Masters programme was pivotal in designing and implementing ICT…

A simulation of T-wave alternans vectocardiographic representation performed by changing the ventricular heart cells action potential duration.

Science.gov (United States)

Janusek, D; Kania, M; Zaczek, R; Zavala-Fernandez, H; Maniewski, R

2014-04-01

The presence of T wave alternans (TWA) in the surface ECG signals has been recognized as a marker of electrical instability, and is hypothesized to be related to patients at increased risk for ventricular arrhythmias. In this paper we present a TWA simulation study. The TWA phenomenon was simulated by changing the duration of the ventricular heart cells action potential. The magnitude was calculated in the surface ECG with the use of the time domain method. The spatially concordant TWA, where during one heart beat all ventricular cells display a short-duration action potential and during the next beat they exhibit a long-duration action potential, as well as the discordant TWA, where at least one region is out of phase, was simulated. The vectocardiographic representation was employed. The obtained results showed a high level of T-loop pattern and location disturbances connected to the discordant TWA simulation in contrast to the concordant one. This result may be explained by the spatial heterogeneity of the ventricular repolarization process, which could be higher for the discordant TWA than for the concordant TWA. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Backpropagating Action Potentials Enable Detection of Extrasynaptic Glutamate by NMDA Receptors

Directory of Open Access Journals (Sweden)

Yu-Wei Wu

2012-05-01

Full Text Available Synaptic NMDA receptors (NMDARs are crucial for neural coding and plasticity. However, little is known about the adaptive function of extrasynaptic NMDARs occurring mainly on dendritic shafts. Here, we find that in CA1 pyramidal neurons, backpropagating action potentials (bAPs recruit shaft NMDARs exposed to ambient glutamate. In contrast, spine NMDARs are “protected,” under baseline conditions, from such glutamate influences by perisynaptic transporters: we detect bAP-evoked Ca2+ entry through these receptors upon local synaptic or photolytic glutamate release. During theta-burst firing, NMDAR-dependent Ca2+ entry either downregulates or upregulates an h-channel conductance (Gh of the cell depending on whether synaptic glutamate release is intact or blocked. Thus, the balance between activation of synaptic and extrasynaptic NMDARs can determine the sign of Gh plasticity. Gh plasticity in turn regulates dendritic input probed by local glutamate uncaging. These results uncover a metaplasticity mechanism potentially important for neural coding and memory formation.

Increased transient Na+ conductance and action potential output in layer 2/3 prefrontal cortex neurons of the fmr1-/y mouse.

Science.gov (United States)

Routh, Brandy N; Rathour, Rahul K; Baumgardner, Michael E; Kalmbach, Brian E; Johnston, Daniel; Brager, Darrin H

2017-07-01

Layer 2/3 neurons of the prefrontal cortex display higher gain of somatic excitability, responding with a higher number of action potentials for a given stimulus, in fmr1 -/y mice. In fmr1 -/y L2/3 neurons, action potentials are taller, faster and narrower. Outside-out patch clamp recordings revealed that the maximum Na + conductance density is higher in fmr1 -/y L2/3 neurons. Measurements of three biophysically distinct K + currents revealed a depolarizing shift in the activation of a rapidly inactivating (A-type) K + conductance. Realistic neuronal simulations of the biophysical observations recapitulated the elevated action potential and repetitive firing phenotype. Fragile X syndrome is the most common form of inherited mental impairment and autism. The prefrontal cortex is responsible for higher order cognitive processing, and prefrontal dysfunction is believed to underlie many of the cognitive and behavioural phenotypes associated with fragile X syndrome. We recently demonstrated that somatic and dendritic excitability of layer (L) 5 pyramidal neurons in the prefrontal cortex of the fmr1 -/y mouse is significantly altered due to changes in several voltage-gated ion channels. In addition to L5 pyramidal neurons, L2/3 pyramidal neurons play an important role in prefrontal circuitry, integrating inputs from both lower brain regions and the contralateral cortex. Using whole-cell current clamp recording, we found that L2/3 pyramidal neurons in prefrontal cortex of fmr1 -/y mouse fired more action potentials for a given stimulus compared with wild-type neurons. In addition, action potentials in fmr1 -/y neurons were significantly larger, faster and narrower. Voltage clamp of outside-out patches from L2/3 neurons revealed that the transient Na + current was significantly larger in fmr1 -/y neurons. Furthermore, the activation curve of somatic A-type K + current was depolarized. Realistic conductance-based simulations revealed that these biophysical changes in Na

Professional development strategies for teaching urban biology teachers to use concept maps effectively

Science.gov (United States)

McGregor Petgrave, Dahlia M.

Many teachers are not adequately prepared to help urban students who have trouble understanding conceptual ideas in biology because these students have little connection to the natural world. This study explored potential professional development strategies to help urban biology teachers use concept maps effectively with various topics in the biology curriculum. A grounded theory approach was used to develop a substantive professional development model for urban biology teachers. Qualitative data were collected through 16 semi-structured interviews of professional developers experienced in working with concept maps in the urban context. An anonymous online survey was used to collect quantitative data from 56 professional developers and teachers to support the qualitative data. The participants were from New York City, recruited through the NY Biology-Chemistry Professional Development Mentor Network and the NY Biology Teachers' Association. According to the participants, map construction, classroom applications, lesson planning, action research, follow-up workshops, and the creation of learning communities are the most effective professional development strategies. The interviewees also proposed English language learning strategies such as picture maps, native word maps, and content reading materials with underlined words. This study contributes to social change by providing a professional development model to use in planning workshops for urban teachers. Urban teachers improve their own conceptual understanding of biology while learning how to implement concept mapping strategies in the classroom. Students whose teachers are better prepared to teach biology in a conceptual manner have the potential of growing into more scientifically literate citizens.

Potentiation of E-4031-induced torsade de pointes by HMR1556 or ATX-II is not predicted by action potential short-term variability or triangulation.

Science.gov (United States)

Michael, G; Dempster, J; Kane, K A; Coker, S J

2007-12-01

Torsade de pointes (TdP) can be induced by a reduction in cardiac repolarizing capacity. The aim of this study was to assess whether IKs blockade or enhancement of INa could potentiate TdP induced by IKr blockade and to investigate whether short-term variability (STV) or triangulation of action potentials preceded TdP. Experiments were performed in open-chest, pentobarbital-anaesthetized, alpha 1-adrenoceptor-stimulated, male New Zealand White rabbits, which received three consecutive i.v. infusions of either the IKr blocker E-4031 (1, 3 and 10 nmol kg(-1) min(-1)), the IKs blocker HMR1556 (25, 75 and 250 nmol kg(-1) min(-1)) or E-4031 and HMR1556 combined. In a second study rabbits received either the same doses of E-4031, the INa enhancer, ATX-II (0.4, 1.2 and 4.0 nmol kg(-1)) or both of these drugs. ECGs and epicardial monophasic action potentials were recorded. HMR1556 alone did not cause TdP but increased E-4031-induced TdP from 25 to 80%. ATX-II alone caused TdP in 38% of rabbits, as did E-4031; 75% of rabbits receiving both drugs had TdP. QT intervals were prolonged by all drugs but the extent of QT prolongation was not related to the occurrence of TdP. No changes in STV were detected and triangulation was only increased after TdP occurred. Giving modulators of ion channels in combination substantially increased TdP but, in this model, neither STV nor triangulation of action potentials could predict TdP.

Real time estimation of generation, extinction and flow of muscle fibre action potentials in high density surface EMG.

Science.gov (United States)

Mesin, Luca

2015-02-01

Developing a real time method to estimate generation, extinction and propagation of muscle fibre action potentials from bi-dimensional and high density surface electromyogram (EMG). A multi-frame generalization of an optical flow technique including a source term is considered. A model describing generation, extinction and propagation of action potentials is fit to epochs of surface EMG. The algorithm is tested on simulations of high density surface EMG (inter-electrode distance equal to 5mm) from finite length fibres generated using a multi-layer volume conductor model. The flow and source term estimated from interference EMG reflect the anatomy of the muscle, i.e. the direction of the fibres (2° of average estimation error) and the positions of innervation zone and tendons under the electrode grid (mean errors of about 1 and 2mm, respectively). The global conduction velocity of the action potentials from motor units under the detection system is also obtained from the estimated flow. The processing time is about 1 ms per channel for an epoch of EMG of duration 150 ms. A new real time image processing algorithm is proposed to investigate muscle anatomy and activity. Potential applications are proposed in prosthesis control, automatic detection of optimal channels for EMG index extraction and biofeedback. Copyright © 2014 Elsevier Ltd. All rights reserved.

Map updates in a dynamic Voronoi data structure

DEFF Research Database (Denmark)

Mioc, Darka; Antón Castro, Francesc/François; Gold, C. M.

2006-01-01

In this paper we are using local and sequential map updates in the Voronoi data structure, which allows us to automatically record each event and performed map updates within the system. These map updates are executed through map construction commands that are composed of atomic actions (geometric...... algorithms for addition, deletion, and motion of spatial objects) on the dynamic Voronoi data structure. The formalization of map commands led to the development of a spatial language comprising a set of atomic operations or constructs on spatial primitives (points and lines), powerful enough to define...

A Framework for Hierarchical Perception-Action Learning Utilizing Fuzzy Reasoning.

Science.gov (United States)

Windridge, David; Felsberg, Michael; Shaukat, Affan

2013-02-01

Perception-action (P-A) learning is an approach to cognitive system building that seeks to reduce the complexity associated with conventional environment-representation/action-planning approaches. Instead, actions are directly mapped onto the perceptual transitions that they bring about, eliminating the need for intermediate representation and significantly reducing training requirements. We here set out a very general learning framework for cognitive systems in which online learning of the P-A mapping may be conducted within a symbolic processing context, so that complex contextual reasoning can influence the P-A mapping. In utilizing a variational calculus approach to define a suitable objective function, the P-A mapping can be treated as an online learning problem via gradient descent using partial derivatives. Our central theoretical result is to demonstrate top-down modulation of low-level perceptual confidences via the Jacobian of the higher levels of a subsumptive P-A hierarchy. Thus, the separation of the Jacobian as a multiplying factor between levels within the objective function naturally enables the integration of abstract symbolic manipulation in the form of fuzzy deductive logic into the P-A mapping learning. We experimentally demonstrate that the resulting framework achieves significantly better accuracy than using P-A learning without top-down modulation. We also demonstrate that it permits novel forms of context-dependent multilevel P-A mapping, applying the mechanism in the context of an intelligent driver assistance system.

Conformal group actions and Segal's cosmology

International Nuclear Information System (INIS)

Werth, J.-E.

1984-01-01

A mathematical description of Segal's cosmological model in the framework of conformal group actions is presented. The relation between conformal and causal group actions on time-orientable Lorentzian manifolds is analysed and several examples are discussed. A criterion for the conformality of a map between Lorentzian manifolds is given. The results are applied to Segal's 'conformal compactification' of Minkowski space. Furthermore, the 'unitary formulation' of Segal's cosmology is regarded. (Author) [pt

Transformation of a Spatial Map across the Hippocampal-Lateral Septal Circuit.

Science.gov (United States)

Tingley, David; Buzsáki, György

2018-05-15

The hippocampus constructs a map of the environment. How this "cognitive map" is utilized by other brain regions to guide behavior remains unexplored. To examine how neuronal firing patterns in the hippocampus are transmitted and transformed, we recorded neurons in its principal subcortical target, the lateral septum (LS). We observed that LS neurons carry reliable spatial information in the phase of action potentials, relative to hippocampal theta oscillations, while the firing rates of LS neurons remained uninformative. Furthermore, this spatial phase code had an anatomical microstructure within the LS and was bound to the hippocampal spatial code by synchronous gamma frequency cell assemblies. Using a data-driven model, we show that rate-independent spatial tuning arises through the dynamic weighting of CA1 and CA3 cell assemblies. Our findings demonstrate that transformation of the hippocampal spatial map depends on higher-order theta-dependent neuronal sequences. Copyright © 2018 Elsevier Inc. All rights reserved.

Geologic Maps as the Foundation of Mineral-Hazards Maps in California

Science.gov (United States)

Higgins, C. T.; Churchill, R. K.; Downey, C. I.; Clinkenbeard, J. P.; Fonseca, M. C.

2010-12-01

The basic geologic map is essential to the development of products that help planners, engineers, government officials, and the general public make decisions concerning natural hazards. Such maps are the primary foundation that the California Geological Survey (CGS) uses to prepare maps that show potential for mineral-hazards. Examples of clients that request these maps are the California Department of Transportation (Caltrans) and California Department of Public Health (CDPH). Largely because of their non-catastrophic nature, mineral hazards have received much less public attention compared to earthquakes, landslides, volcanic eruptions, and floods. Nonetheless, mineral hazards can be a major concern locally when considering human health and safety and potential contamination of the environment by human activities such as disposal of earth materials. To address some of these concerns, the CGS has focused its mineral-hazards maps on naturally occurring asbestos (NOA), radon, and various potentially toxic metals as well as certain artificial features such as mines and oil and gas wells. The maps range in scope from statewide to counties and Caltrans districts to segments of selected highways. To develop the hazard maps, the CGS begins with traditional paper and digital versions of basic geologic maps, which are obtained from many sources such as its own files, the USGS, USDA Forest Service, California Department of Water Resources, and counties. For each study area, these maps present many challenges of compilation related to vintage, scale, definition of units, and edge-matching across map boundaries. The result of each CGS compilation is a digital geologic layer that is subsequently reinterpreted and transformed into new digital layers (e.g., lithologic) that focus on the geochemical and mineralogical properties of the area’s earth materials and structures. These intermediate layers are then integrated with other technical data to derive final digital layers

High-precision geologic mapping to evaluate the potential for seismic surface rupture at TA-55, Los Alamos National Laboratory

International Nuclear Information System (INIS)

Gardner, J.N.; Lavine, A.; Vaniman, D.; WoldeGabriel, G.

1998-06-01

In this report the authors document results of high-precision geologic mapping in the vicinity of TA-55 that has been done to identify parts of the southern portion of the Rendija Canyon Fault, or any other faults, with the potential for seismic surface rupture. To assess the potential for surface rupture at TA-55, an area of approximately 3 square miles that includes the Los Alamos County Landfill and Twomile, Mortandad, and Sandia Canyons has been mapped in detail. Map units are mostly cooling or flow units within the Tshirege Member (1.2 Ma) of the Bandelier Tuff. Stratigraphic markers that are useful for determining offsets in the map area include a distinct welding break at or near the cooling Unit 2-Unit 3 contact, and the Unit 3-Unit 4 contact. At the County Landfill the contact between the Tshirege Member of the Bandelier Tuff and overlying Quaternary alluvium has also been mapped. The mapping indicates that there is no faulting in the near-surface directly below TA-55, and that the closest fault is about 1500 feet west of the Plutonium Facility. Faulting is more abundant on the western edge of the map area, west of TA-48 in uppermost Mortandad Canyon, upper Sandia Canyon, and at the County Landfill. Measured vertical offsets on the faults range from 1 to 8 feet on mapped Bandelier Tuff contacts. Faulting exposed at the Los Alamos County Landfill has deformed a zone over 1000 feet wide, and has a net vertical down-to-the-west displacement of at least 15 feet in the Bandelier Tuff. Individual faults at the landfill have from less than 1 foot to greater than 15 feet of vertical offset on the Bandelier Tuff. Most faults in the landfill trend N-S, N20W, or N45E. Results of the mapping indicate that the Rendija Canyon Fault does not continue directly south to TA-55. At present, the authors have insufficient data to connect faulting they have mapped to areas of known faulting to the north or south of the study area

Compound muscle action potential duration in critical illness neuromyopathy.

Science.gov (United States)

Kramer, Christopher L; Boon, Andrea J; Harper, C Michel; Goodman, Brent P

2018-03-01

We sought to determine the specificity of compound muscle action potential (CMAP) durations and amplitudes in a large critical illness neuromyopathy (CINM) cohort relative to controls with other neuromuscular conditions. Fifty-eight patients with CINM who had been seen over a 17-year period were retrospectively studied. Electrodiagnostic findings of the CINM cohort were compared with patients with axonal peripheral neuropathy and myopathy due to other causes. Mean CMAP durations were prolonged, and mean CMAP amplitudes were severely reduced both proximally and distally in all nerves studied in the CINM cohort relative to the control groups. The specificity of prolonged CMAP durations for CINM approached 100% if they were encountered in more than 1 nerve. Prolonged, low-amplitude CMAPs occur more frequently and with greater severity in CINM patients than in neuromuscular controls with myopathy and axonal neuropathy and are highly specific for the diagnosis of CINM. Muscle Nerve 57: 395-400, 2018. © 2017 Wiley Periodicals, Inc.

CONSTRAINING THE MILKY WAY POTENTIAL WITH A SIX-DIMENSIONAL PHASE-SPACE MAP OF THE GD-1 STELLAR STREAM

International Nuclear Information System (INIS)

Koposov, Sergey E.; Rix, Hans-Walter; Hogg, David W.

2010-01-01

The narrow GD-1 stream of stars, spanning 60 0 on the sky at a distance of ∼10 kpc from the Sun and ∼15 kpc from the Galactic center, is presumed to be debris from a tidally disrupted star cluster that traces out a test-particle orbit in the Milky Way halo. We combine Sloan Digital Sky Survey (SDSS) photometry, USNO-B astrometry, and SDSS and Calar Alto spectroscopy to construct a complete, empirical six-dimensional (6D) phase-space map of the stream. We find that an eccentric orbit in a flattened isothermal potential describes this phase-space map well. Even after marginalizing over the stream orbital parameters and the distance from the Sun to the Galactic center, the orbital fit to GD-1 places strong constraints on the circular velocity at the Sun's radius V c = 224 ± 13 km s -1 and total potential flattening q Φ = 0.87 +0.07 -0.04 . When we drop any informative priors on V c , the GD-1 constraint becomes V c = 221 ± 18 km s -1 . Our 6D map of GD-1, therefore, yields the best current constraint on V c and the only strong constraint on q Φ at Galactocentric radii near R ∼ 15 kpc. Much, if not all, of the total potential flattening may be attributed to the mass in the stellar disk, so the GD-1 constraints on the flattening of the halo itself are weak: q Φ,halo > 0.89 at 90% confidence. The greatest uncertainty in the 6D map and the orbital analysis stems from the photometric distances, which will be obviated by GAIA.

Sensitivity of the amplitude of the single muscle fibre action potential to microscopic volume conduction parameters

NARCIS (Netherlands)

Alberts, B.A.; Rutten, Wim; Wallinga, W.; Boom, H.B.K.

1988-01-01

A microscopic model of volume conduction was applied to examine the sensitivity of the single muscle fibre action potential to variations in parameters of the source and of the volume conductor, such as conduction velocity, intracellular conductivity and intracellular volume fraction. The model

Youth Participatory Action Research and Educational Transformation: The Potential of Intertextuality as a Methodological Tool

Science.gov (United States)

Bertrand, Melanie

2016-01-01

In this article, Melanie Bertrand explores the potential of using the concept of intertextuality--which captures the way snippets of written or spoken text from one source become incorporated into other sources--in the study and practice of youth participatory action research (YPAR). Though this collective and youth-centered form of research…

Cowichan Valley energy mapping and modelling. Report 3 - Analysis of potentially applicable distributed energy opportunities. Final report. [Vancouver Island, Canada

Energy Technology Data Exchange (ETDEWEB)

NONE

2012-06-15

The driving force behind the Integrated Energy Mapping and Analysis project was the identification and analysis of a suite of pathways that the Cowichan Valley Regional District (CVRD) can utilise to increase its energy resilience, as well as reduce energy consumption and GHG emissions, with a primary focus on the residential sector. Mapping and analysis undertaken will support provincial energy and GHG reduction targets, and the suite of pathways outlined will address a CVRD internal target that calls for 75% of the region's energy within the residential sector to come from locally sourced renewables by 2050. The target has been developed as a mechanism to meet resilience and climate action target. The maps and findings produced are to be integrated as part of a regional policy framework currently under development. The third task built upon the findings of the previous two and undertook an analysis of potentially applicable distributed energy opportunities. These opportunities were analysed given a number of different parameters, which were decided upon in consultation with the CVRD. The primary output of this task was a series of cost figures for the various technologies, thus allowing comparison on a cents/kWh basis. All of the cost figures from this task have been entered into a tailor made Excel model. This 'technology cost' model is linked to the Excel scenario model utilised in task 4. As a result, as technology costs change, they can be updated accordingly and be reflected in the scenarios. Please note, that the technologies considered at present in the technology cost model are well-proven technologies, available in the market today, even though the output is being used for an analysis of development until 2050. Task 3 results are detailed in this report and both presents an initial screening for various local renewable energies, and provides the CVRD with the means of evaluating the costs and benefits of local energy productions versus

High Resolution Decision Maps for Urban Planning: A Combined Analysis of Urban Flooding and Thermal Stress Potential In Asia and Europe

Directory of Open Access Journals (Sweden)

Boogaard Floris

2017-01-01

Full Text Available Urban flooding and thermal stress have become key issues for many cities around the world. With the continuing effects of climate change, these two issues will become more acute and will add to the serious problems already experienced in dense urban areas. Therefore, the sectors of public health and disaster management are in the need of tools that can assess the vulnerability to floods and thermal stress. The present paper deals with the combination of innovative tools to address this challenge. Three cities in different climatic regions with various urban contexts have been selected as the pilot areas to demonstrate these tools. These cities are Tainan (Taiwan, Ayutthaya (Thailand and Groningen (Netherlands. For these cities, flood maps and heat stress maps were developed and used for the comparison analysis. The flood maps produced indicate vulnerable low-lying areas, whereas thermal stress maps indicate open, unshaded areas where high Physiological Equivalent Temperature (PET values (thermal comfort can be expected. The work to date indicates the potential of combining two different kinds of maps to identify and analyse the problem areas. These maps could be further improved and used by urban planners and other stakeholders to assess the resilience and well-being of cities. The work presented shows that the combined analysis of such maps also has a strong potential to be used for the analysis of other challenges in urban dense areas such as air and water pollution, immobility and noise disturbance.

BK channels regulate spontaneous action potential rhythmicity in the suprachiasmatic nucleus.

Directory of Open Access Journals (Sweden)

Jack Kent

Full Text Available BACKGROUND: Circadian ( approximately 24 hr rhythms are generated by the central pacemaker localized to the suprachiasmatic nucleus (SCN of the hypothalamus. Although the basis for intrinsic rhythmicity is generally understood to rely on transcription factors encoded by "clock genes", less is known about the daily regulation of SCN neuronal activity patterns that communicate a circadian time signal to downstream behaviors and physiological systems. Action potentials in the SCN are necessary for the circadian timing of behavior, and individual SCN neurons modulate their spontaneous firing rate (SFR over the daily cycle, suggesting that the circadian patterning of neuronal activity is necessary for normal behavioral rhythm expression. The BK K(+ channel plays an important role in suppressing spontaneous firing at night in SCN neurons. Deletion of the Kcnma1 gene, encoding the BK channel, causes degradation of circadian behavioral and physiological rhythms. METHODOLOGY/PRINCIPAL FINDINGS: To test the hypothesis that loss of robust behavioral rhythmicity in Kcnma1(-/- mice is due to the disruption of SFR rhythms in the SCN, we used multi-electrode arrays to record extracellular action potentials from acute wild-type (WT and Kcnma1(-/- slices. Patterns of activity in the SCN were tracked simultaneously for up to 3 days, and the phase, period, and synchronization of SFR rhythms were examined. Loss of BK channels increased arrhythmicity but also altered the amplitude and period of rhythmic activity. Unexpectedly, Kcnma1(-/- SCNs showed increased variability in the timing of the daily SFR peak. CONCLUSIONS/SIGNIFICANCE: These results suggest that BK channels regulate multiple aspects of the circadian patterning of neuronal activity in the SCN. In addition, these data illustrate the characteristics of a disrupted SCN rhythm downstream of clock gene-mediated timekeeping and its relationship to behavioral rhythms.

A Commune-Level Groundwater Potential Map for the Republic of Mali

Directory of Open Access Journals (Sweden)

Silvia Díaz-Alcaide

2017-10-01

Full Text Available Groundwater represents an essential resource in sub-Saharan Africa, where several hundred million people rely on aquifers for domestic supply. This paper presents a method to map groundwater potential in the Republic of Mali based on a spatially-distributed database of 26,040 boreholes. The database includes exhaustive information on key parameters such as borehole location, success rate of borehole production, depth, yield, static groundwater level or water quality. Representative variables were classified and interpreted jointly to develop a groundwater potential index for each of the 703 communes in Mali. This provides a methodological novelty because groundwater potential studies typically rely on indirect indicators such as lineaments, slope, soil moisture and landforms. Also, such large borehole databases have seldom been used to estimate groundwater potential. The highest indexes were obtained for the areas in and around the River Niger’s Inner Delta, including southern Tombouctou and the central parts of the Ségou and Mopti Regions. The lower Precambrian formations, which include the country’s thoroughly populated southern plateau, had moderate scores. The lowest groundwater potential was found in the northern part of the Kayes and Koulikoro Regions, as well as in the entire region of Kidal. By providing results at the commune scale, these outcomes show that groundwater potential across the country’s geological and hydrogeological units can be highly variable, and that local and regional-scale information may be useful for groundwater management purposes. These results are policy-relevant in a context of rapid change and population growth, where groundwater resources can be expected to be increasingly relied upon in the coming years.

The effect of recording site on extracted features of motor unit action potential.

Science.gov (United States)

Artuğ, N Tuğrul; Goker, Imran; Bolat, Bülent; Osman, Onur; Kocasoy Orhan, Elif; Baslo, M Baris

2016-06-01

Motor unit action potential (MUAP), which consists of individual muscle fiber action potentials (MFAPs), represents the electrical activity of the motor unit. The values of the MUAP features are changed by denervation and reinnervation in neurogenic involvement as well as muscle fiber loss with increased diameter variability in myopathic diseases. The present study is designed to investigate how increased muscle fiber diameter variability affects MUAP parameters in simulated motor units. In order to detect this variation, simulated MUAPs were calculated both at the innervation zone where the MFAPs are more synchronized, and near the tendon, where they show increased temporal dispersion. Reinnervation in neurogenic state increases MUAP amplitude for the recordings at both the innervation zone and near the tendon. However, MUAP duration and the number of peaks significantly increased in a case of myopathy for recordings near the tendon. Furthermore, of the new features, "number of peaks×spike duration" was found as the strongest indicator of MFAP dispersion in myopathy. MUAPs were also recorded from healthy participants in order to investigate the biological counterpart of the simulation data. MUAPs which were recorded near to tendon revealed significantly prolonged duration and decreased amplitude. Although the number of peaks was increased by moving the needle near to tendon, this was not significant. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Control of clustered action potential firing in a mathematical model of entorhinal cortex stellate cells.

Science.gov (United States)

Tait, Luke; Wedgwood, Kyle; Tsaneva-Atanasova, Krasimira; Brown, Jon T; Goodfellow, Marc

2018-07-14

The entorhinal cortex is a crucial component of our memory and spatial navigation systems and is one of the first areas to be affected in dementias featuring tau pathology, such as Alzheimer's disease and frontotemporal dementia. Electrophysiological recordings from principle cells of medial entorhinal cortex (layer II stellate cells, mEC-SCs) demonstrate a number of key identifying properties including subthreshold oscillations in the theta (4-12 Hz) range and clustered action potential firing. These single cell properties are correlated with network activity such as grid firing and coupling between theta and gamma rhythms, suggesting they are important for spatial memory. As such, experimental models of dementia have revealed disruption of organised dorsoventral gradients in clustered action potential firing. To better understand the mechanisms underpinning these different dynamics, we study a conductance based model of mEC-SCs. We demonstrate that the model, driven by extrinsic noise, can capture quantitative differences in clustered action potential firing patterns recorded from experimental models of tau pathology and healthy animals. The differential equation formulation of our model allows us to perform numerical bifurcation analyses in order to uncover the dynamic mechanisms underlying these patterns. We show that clustered dynamics can be understood as subcritical Hopf/homoclinic bursting in a fast-slow system where the slow sub-system is governed by activation of the persistent sodium current and inactivation of the slow A-type potassium current. In the full system, we demonstrate that clustered firing arises via flip bifurcations as conductance parameters are varied. Our model analyses confirm the experimentally suggested hypothesis that the breakdown of clustered dynamics in disease occurs via increases in AHP conductance. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Data Management Plan: HarassMap

OpenAIRE

Reem Wael

2017-01-01

HarassMap is an Egyptian organisation that works to create an environment where sexual harassment is not tolerated, and where individuals and institutions take action against it. For the purpose of this project, the project team cleaned up, organised, and made openly available for the public to access and use through a web portal, three main types of data: Crowdsourced reports of sexual harassment incidents (reports on HarassMap’s online reporting and mapping system) - CSV and XL...

Ionization from short-range potential under action of electromagnetic field of complex configuration

CERN Document Server

Rodionov, V N; Kravtsova, G A

2002-01-01

The transcendental equation for the complex energy is obtained on the basis of the exactly solvable 3D model of the short-acting potential and the Green time function in the intensive electromagnetic field, constituting the combination of the constant magnetic field and the circular-polarization wave field. The electron quasistationary states parameters in the delta-potential with an account of the action of the intensive external field of complex configuration are calculated. The problem on the possibility of stabilizing the bound states decay of the spinor and scalar particles through the intensive magnetic field is clarified. It is established that the obtained results regime the reexamination of the accepted notion on the stabilizing role of the strong magnetic field by the atoms ionization

Small-conductance calcium-activated potassium (SK) channels contribute to action potential repolarization in human atria

DEFF Research Database (Denmark)

Skibsbye, Lasse; Poulet, Claire; Diness, Jonas Goldin

2014-01-01

(+) currents by ∼15% and prolonged action potential duration (APD), but no effect was observed in myocytes from AF patients. In trabeculae muscle strips from right atrial appendages of SR patients, both compounds increased APD and effective refractory period, and depolarized the resting membrane potential......, while only NS8593 induced these effects in tissue from AF patients. SK channel inhibition did not alter any electrophysiological parameter in human interventricular septum tissue. CONCLUSIONS: SK channels are present in human atria where they participate in repolarization. SK2 and SK3 were down...

Regulation of gap junction conductance by calcineurin through Cx43 phosphorylation: implications for action potential conduction.

Science.gov (United States)

Jabr, Rita I; Hatch, Fiona S; Salvage, Samantha C; Orlowski, Alejandro; Lampe, Paul D; Fry, Christopher H

2016-11-01

Cardiac arrhythmias are associated with raised intracellular [Ca 2+ ] and slowed action potential conduction caused by reduced gap junction (GJ) electrical conductance (Gj). Ventricular GJs are composed of connexin proteins (Cx43), with Gj determined by Cx43 phosphorylation status. Connexin phosphorylation is an interplay between protein kinases and phosphatases but the precise pathways are unknown. We aimed to identify key Ca 2+ -dependent phosphorylation sites on Cx43 that regulate cardiac gap junction conductance and action potential conduction velocity. We investigated the role of the Ca 2+ -dependent phosphatase, calcineurin. Intracellular [Ca 2+ ] was raised in guinea-pig myocardium by a low-Na solution or increased stimulation. Conduction velocity and Gj were measured in multicellular strips. Phosphorylation of Cx43 serine residues (S365 and S368) and of the intermediary regulator I1 at threonine35 was measured by Western blot. Measurements were made in the presence and absence of inhibitors to calcineurin, I1 or protein phosphatase-1 and phosphatase-2.Raised [Ca 2 + ] i decreased Gj, reduced Cx43 phosphorylation at S365 and increased it at S368; these changes were reversed by calcineurin inhibitors. Cx43-S368 phosphorylation was reversed by the protein kinase C inhibitor chelerythrine. Raised [Ca 2+ ] i also decreased I1 phosphorylation, also prevented by calcineurin inhibitors, to increase activity of the Ca 2+ -independent phosphatase, PPI. The PP1 inhibitor, tautomycin, prevented Cx43-365 dephosphorylation, Cx43-S368 phosphorylation and Gj reduction in raised [Ca 2+ ] i . PP2A had no role. Conduction velocity was reduced by raised [Ca 2+ ] i and reversed by calcineurin inhibitors. Reduced action potential conduction and Gj in raised [Ca 2+ ] are regulated by calcineurin-dependent Cx43-S365 phosphorylation, leading to Cx43-S368 dephosphorylation. The calcineurin action is indirect, via I1 dephosphorylation and subsequent activation of PP1.

Using concept mapping in the knowledge-to-action process to compare stakeholder opinions on barriers to use of cancer screening among South Asians.

Science.gov (United States)

Lobb, Rebecca; Pinto, Andrew D; Lofters, Aisha

2013-03-23

Using the knowledge-to-action (KTA) process, this study examined barriers to use of evidence-based interventions to improve early detection of cancer among South Asians from the perspective of multiple stakeholders. In 2011, we used concept mapping with South Asian residents, and representatives from health service and community service organizations in the region of Peel Ontario. As part of concept mapping procedures, brainstorming sessions were conducted with stakeholders (n = 53) to identify barriers to cancer screening among South Asians. Participants (n = 46) sorted barriers into groups, and rated barriers from lowest (1) to highest (6) in terms of importance for use of mammograms, Pap tests and fecal occult blood tests, and how feasible it would be to address them. Multi-dimensional scaling, cluster analysis, and descriptive statistics were used to analyze the data. A total of 45 unique barriers to use of mammograms, Pap tests, and fecal occult blood tests among South Asians were classified into seven clusters using concept mapping procedures: patient's beliefs, fears, lack of social support; health system; limited knowledge among residents; limited knowledge among physicians; health education programs; ethno-cultural discordance with the health system; and cost. Overall, the top three ranked clusters of barriers were 'limited knowledge among residents,' 'ethno-cultural discordance,' and 'health education programs' across surveys. Only residents ranked 'cost' second in importance for fecal occult blood testing, and stakeholders from health service organizations ranked 'limited knowledge among physicians' third for the feasibility survey. Stakeholders from health services organizations ranked 'limited knowledge among physicians' fourth for all other surveys, but this cluster consistently ranked lowest among residents. The limited reach of cancer control programs to racial and ethnic minority groups is a critical implementation issue that requires attention

Mapping of groundwater potential zones in Salem Chalk Hills, Tamil Nadu, India, using remote sensing and GIS techniques.

Science.gov (United States)

Thilagavathi, N; Subramani, T; Suresh, M; Karunanidhi, D

2015-04-01

This study proposes to introduce the remote sensing and geographic information system (GIS) techniques in mapping the groundwater potential zones. Remote sensing and GIS techniques have been used to map the groundwater potential zones in Salem Chalk Hills, Tamil Nadu, India. Charnockites and fissile hornblende biotite gneiss are the major rock types in this region. Dunites and peridodites are the ultramafic rocks which cut across the foliation planes of the gneisses and are highly weathered. It comprises magnesite and chromite deposits which are excavated by five mining companies by adopting bench mining. The thickness of weathered and fracture zone varies from 2.2 to 50 m in gneissic formation and 5.8 to 55 m in charnockite. At the contacts of gneiss and charnockite, the thickness ranges from 9.0 to 90.8 m favoring good groundwater potential. The mine lease area is underlined by fractured and sheared hornblende biotite gneiss where groundwater potential is good. Water catchment tanks in this area of 5 km radius are small to moderate in size and are only seasonal. They remain dry during summer seasons. As perennial water resources are remote, the domestic and agricultural activities in this region depend mainly upon the groundwater resources. The mines are located in gently slope area, and accumulation of water is not observed except in mine pits even during the monsoon period. Therefore, it is essential to map the groundwater potential zones for proper management of the aquifer system. Satellite imageries were also used to extract lineaments, hydrogeomorphic landforms, drainage patterns, and land use, which are the major controlling factors for the occurrence of groundwater. Various thematic layers pertaining to groundwater existence such as geology, geomorphology, land use/land cover, lineament, lineament density, drainage, drainage density, slope, and soil were generated using GIS tools. By integrating all the above thematic layers based on the ranks and

Towards automated electron holographic tomography for 3D mapping of electrostatic potentials

Energy Technology Data Exchange (ETDEWEB)

Wolf, Daniel, E-mail: Daniel.Wolf@Triebenberg.de [Triebenberg Laboratory, Institute of Structure Physics, Technische Universitaet Dresden, 01062 Dresden (Germany); Lubk, Axel; Lichte, Hannes [Triebenberg Laboratory, Institute of Structure Physics, Technische Universitaet Dresden, 01062 Dresden (Germany); Friedrich, Heiner [Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Sorbonnelaan 16, 3584 CA, Utrecht (Netherlands)

2010-04-15

Electron-holographic tomography (EHT), that is, the combination of off-axis electron holography with electron tomography, was successfully applied for the quantitative 3D mapping of electrostatic potentials at the nanoscale. Here we present the first software package (THOMAS) for semi-automated acquisition of holographic tilt series, a prerequisite for efficient data collection. Using THOMAS, the acquisition time for a holographic tilt series, consisting of object and reference holograms, is reduced by a factor of five on average, compared to the previous, completely manual approaches. Moreover, the existing software packages for retrieving amplitude and phase information from electron holograms have been extended, now including a one-step procedure for holographic tilt series reconstruction. Furthermore, a modified SIRT algorithm (WSIRT) was implemented for the quantitative 3D reconstruction of the electrostatic potential from the aligned phase tilt series. Finally, the application of EHT to a polystyrene latex sphere test-specimen and a pn-doped Ge 'needle'-shaped specimen are presented, illustrating the quantitative character of EHT. For both specimens the mean inner potential (MIP) values were accurately determined from the reconstructed 3D potential. For the Ge specimen, additionally the 'built-in' voltage across the pn junction of 0.5 V was obtained.

Exploring the potential offered by legacy soil databases for ecosystem services mapping of Central African soils

Science.gov (United States)

Verdoodt, Ann; Baert, Geert; Van Ranst, Eric

2014-05-01

Central African soil resources are characterised by a large variability, ranging from stony, shallow or sandy soils with poor life-sustaining capabilities to highly weathered soils that recycle and support large amounts of biomass. Socio-economic drivers within this largely rural region foster inappropriate land use and management, threaten soil quality and finally culminate into a declining soil productivity and increasing food insecurity. For the development of sustainable land use strategies targeting development planning and natural hazard mitigation, decision makers often rely on legacy soil maps and soil profile databases. Recent development cooperation financed projects led to the design of soil information systems for Rwanda, D.R. Congo, and (ongoing) Burundi. A major challenge is to exploit these existing soil databases and convert them into soil inference systems through an optimal combination of digital soil mapping techniques, land evaluation tools, and biogeochemical models. This presentation aims at (1) highlighting some key characteristics of typical Central African soils, (2) assessing the positional, geographic and semantic quality of the soil information systems, and (3) revealing its potential impacts on the use of these datasets for thematic mapping of soil ecosystem services (e.g. organic carbon storage, pH buffering capacity). Soil map quality is assessed considering positional and semantic quality, as well as geographic completeness. Descriptive statistics, decision tree classification and linear regression techniques are used to mine the soil profile databases. Geo-matching as well as class-matching approaches are considered when developing thematic maps. Variability in inherent as well as dynamic soil properties within the soil taxonomic units is highlighted. It is hypothesized that within-unit variation in soil properties highly affects the use and interpretation of thematic maps for ecosystem services mapping. Results will mainly be based

Towards an EO-based Landslide Web Mapping and Monitoring Service

Science.gov (United States)

Hölbling, Daniel; Weinke, Elisabeth; Albrecht, Florian; Eisank, Clemens; Vecchiotti, Filippo; Friedl, Barbara; Kociu, Arben

2017-04-01

resolution (VHR) sensors, e.g. Landsat, Sentinel-2, SPOT-5, WorldView-2/3, was acquired for different study areas in the Alps. Object-based image analysis (OBIA) methods were used for semi-automated mapping of landslides. Selected mapping routines and results, including a step-by-step guidance, are integrated in the service by means of a web processing chain. This allows the user to gain insights into the service idea, the potential of semi-automated mapping methods, and the applicability of various satellite data for specific landslide mapping tasks. Moreover, an easy-to use and guided classification workflow, which includes image segmentation, statistical classification and manual editing options, enables the user to perform his/her own analyses. For validation, the classification results can be downloaded or compared against uploaded reference data using the implemented tools. Furthermore, users can compare the classification results to freely available data such as OpenStreetMap to identify landslide-affected infrastructure (e.g. roads, buildings). They also can upload infrastructure data available at their organization for specific assessments or monitor the evolution of selected landslides over time. Further actions will include the validation of the service in collaboration with stakeholders, decision makers and experts, which is essential to produce landslide information products that can assist the targeted management of natural hazards, and the evaluation of the potential towards the development of an operational Copernicus downstream service.

The geo-genic radon potential map of the aspiring 'Buzau Land' Geo-park

International Nuclear Information System (INIS)

Moldovan, M. C.; Burghele, B. D.; Roba, C. A.; Sferle, T. L.; Buterez, C.; Mitrofan, H.

2017-01-01

Mapping the geo-genic radon potential in Buzau County is part of a research project aiming to apply research for sustainable development and economic growth following the principles of geo-conservation in order to support the 'Buzau Land' UNESCO Geo-park initiative. The mapping of geo-genic radon will be used as an overview for planning purposes. The main geological formations of the studied area were identified as Cretaceous and Paleogene flysch, included in a thin-skinned nappes pile and consisting of alternating sandstones, marls, clays and, subordinately, conglomerates, all tightly folded or faulted. Significant variations in the concentration of radon were therefore determined in the ground. However, no high values were determined, the maximum measured activity concentration being 101.6 kBq m -3 . (authors)

Antimicrobial Properties of Plant Essential Oils against Human Pathogens and Their Mode of Action: An Updated Review

Directory of Open Access Journals (Sweden)

Mallappa Kumara Swamy

2016-01-01

Full Text Available A wide range of medicinal and aromatic plants (MAPs have been explored for their essential oils in the past few decades. Essential oils are complex volatile compounds, synthesized naturally in different plant parts during the process of secondary metabolism. Essential oils have great potential in the field of biomedicine as they effectively destroy several bacterial, fungal, and viral pathogens. The presence of different types of aldehydes, phenolics, terpenes, and other antimicrobial compounds means that the essential oils are effective against a diverse range of pathogens. The reactivity of essential oil depends upon the nature, composition, and orientation of its functional groups. The aim of this article is to review the antimicrobial potential of essential oils secreted from MAPs and their possible mechanisms of action against human pathogens. This comprehensive review will benefit researchers who wish to explore the potential of essential oils in the development of novel broad-spectrum key molecules against a broad range of drug-resistant pathogenic microbes.

Antimicrobial Properties of Plant Essential Oils against Human Pathogens and Their Mode of Action: An Updated Review

Science.gov (United States)

2016-01-01

A wide range of medicinal and aromatic plants (MAPs) have been explored for their essential oils in the past few decades. Essential oils are complex volatile compounds, synthesized naturally in different plant parts during the process of secondary metabolism. Essential oils have great potential in the field of biomedicine as they effectively destroy several bacterial, fungal, and viral pathogens. The presence of different types of aldehydes, phenolics, terpenes, and other antimicrobial compounds means that the essential oils are effective against a diverse range of pathogens. The reactivity of essential oil depends upon the nature, composition, and orientation of its functional groups. The aim of this article is to review the antimicrobial potential of essential oils secreted from MAPs and their possible mechanisms of action against human pathogens. This comprehensive review will benefit researchers who wish to explore the potential of essential oils in the development of novel broad-spectrum key molecules against a broad range of drug-resistant pathogenic microbes. PMID:28090211

Using the Large Fire Simulator System to map wildland fire potential for the conterminous United States

Science.gov (United States)

LaWen Hollingsworth; James Menakis

2010-01-01

This project mapped wildland fire potential (WFP) for the conterminous United States by using the large fire simulation system developed for Fire Program Analysis (FPA) System. The large fire simulation system, referred to here as LFSim, consists of modules for weather generation, fire occurrence, fire suppression, and fire growth modeling. Weather was generated with...

VEGETATION MAPPING IN WETLANDS

Directory of Open Access Journals (Sweden)

F. PEDROTTI

2004-01-01

Full Text Available The current work examines the main aspects of wetland vegetation mapping, which can be summarized as analysis of the ecological-vegetational (ecotone gradients; vegetation complexes; relationships between vegetation distribution and geomorphology; vegetation of the hydrographic basin lo which the wetland in question belongs; vegetation monitoring with help of four vegetation maps: phytosociological map of the real and potential vegetation, map of vegetation dynamical tendencies, map of vegetation series.

Single K ATP channel opening in response to action potential firing in mouse dentate granule neurons.

Science.gov (United States)

Tanner, Geoffrey R; Lutas, Andrew; Martínez-François, Juan Ramón; Yellen, Gary

2011-06-08

ATP-sensitive potassium channels (K(ATP) channels) are important sensors of cellular metabolic state that link metabolism and excitability in neuroendocrine cells, but their role in nonglucosensing central neurons is less well understood. To examine a possible role for K(ATP) channels in modulating excitability in hippocampal circuits, we recorded the activity of single K(ATP) channels in cell-attached patches of granule cells in the mouse dentate gyrus during bursts of action potentials generated by antidromic stimulation of the mossy fibers. Ensemble averages of the open probability (p(open)) of single K(ATP) channels over repeated trials of stimulated spike activity showed a transient increase in p(open) in response to action potential firing. Channel currents were identified as K(ATP) channels through blockade with glibenclamide and by comparison with recordings from Kir6.2 knock-out mice. The transient elevation in K(ATP) p(open) may arise from submembrane ATP depletion by the Na(+)-K(+) ATPase, as the pump blocker strophanthidin reduced the magnitude of the elevation. Both the steady-state and stimulus-elevated p(open) of the recorded channels were higher in the presence of the ketone body R-β-hydroxybutyrate, consistent with earlier findings that ketone bodies can affect K(ATP) activity. Using perforated-patch recording, we also found that K(ATP) channels contribute to the slow afterhyperpolarization following an evoked burst of action potentials. We propose that activity-dependent opening of K(ATP) channels may help granule cells act as a seizure gate in the hippocampus and that ketone-body-mediated augmentation of the activity-dependent opening could in part explain the effect of the ketogenic diet in reducing epileptic seizures.

The Effects of Action Potential Stimulation on Pain, Swelling and Function of Patients with Knee Osteoarthritis

Directory of Open Access Journals (Sweden)

Razieh Sepehri

2012-06-01

Full Text Available Background: Knee osteoarthritis (OA is one of the most prevalent joint diseases. Electrical muscle stimulation is effective to improve its symptoms. Today, action potential stimulation (APS with various currents and periods is used to treat OA. This study aims at analyzing the effect of action potential stimulation in improving knee OA symptoms. Materials and Methods: In this clinical trial, patients with mild to moderate knee OA divided randomly in two groups each had 15 people. Along with the conventional exercises of physiotherapy, one group received 16 minutes action potential stimulation with the lowest intensity (sensible; but the other group besides receiving the conventional exercises of physiotherapy was connected into a plugged off machine for 16 minutes. Certain variables were measured and recorded four times. Results: Comparing the variables before and after intervention did not show any meaningful difference between the two groups. But within group, pain with p=0.0001 showed a meaningful decrease. Decreasing of swelling (inflammation in group 1 and 2 was meaningful with p<0.001 and p<0.001, respectively. For group 1, knee flexion range was improved meaningfully between first and fourth times as p<0.031, but it was not meaningful for group 2. Duration of 50 meters walking and step up and down from three steps significantly decreased in both groups. Conclusion: Although there was no significant difference in variables between two groups, but within both groups’ pain and swelling decreased and functional ability increased, thus, it can be concluded that type of APS does not play a key role in treating knee OA.

Alteration, slope-classified alteration, and potential lahar inundation maps of volcanoes for the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Volcano Archive

Science.gov (United States)

Mars, John C.; Hubbard, Bernard E.; Pieri, David; Linick, Justin

2015-01-01

This study identifies areas prone to lahars from hydrothermally altered volcanic edifices on a global scale, using visible and near infrared (VNIR) and short wavelength infrared (SWIR) reflectance data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and digital elevation data from the ASTER Global Digital Elevation Model (GDEM) dataset. This is the first study to create a global database of hydrothermally altered volcanoes showing quantitatively compiled alteration maps and potentially affected drainages, as well as drainage-specific maps illustrating modeled lahars and their potential inundation zones. We (1) identified and prioritized 720 volcanoes based on population density surrounding the volcanoes using the Smithsonian Institution Global Volcanism Program database (GVP) and LandScan™ digital population dataset; (2) validated ASTER hydrothermal alteration mapping techniques using Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) and ASTER data for Mount Shasta, California, and Pico de Orizaba (Citlaltépetl), Mexico; (3) mapped and slope-classified hydrothermal alteration using ASTER VNIR-SWIR reflectance data on 100 of the most densely populated volcanoes; (4) delineated drainages using ASTER GDEM data that show potential flow paths of possible lahars for the 100 mapped volcanoes; (5) produced potential alteration-related lahar inundation maps using the LAHARZ GIS code for Iztaccíhuatl, Mexico, and Mount Hood and Mount Shasta in the United States that illustrate areas likely to be affected based on DEM-derived volume estimates of hydrothermally altered rocks and the ~2x uncertainty factor inherent within a statistically-based lahar model; and (6) saved all image and vector data for 3D and 2D display in Google Earth™, ArcGIS® and other graphics display programs. In addition, these data are available from the ASTER Volcano Archive (AVA) for distribution (available at http://ava.jpl.nasa.gov/recent_alteration_zones.php).

Application of ecological mapping

International Nuclear Information System (INIS)

Sherk, J.A.

1982-01-01

The US Fish and Wildlife Service has initiated the production of a comprehensive ecological inventory map series for use as a major new planning tool. Important species data along with special land use designations are displayed on 1:250,000 scale topographic base maps. Sets of maps have been published for the Atlantic and Pacific coastal areas of the United States. Preparation of a map set for the Gulf of Mexico is underway at the present time. Potential application of ecological inventory map series information to a typical land disposal facility could occur during the narrowing of the number of possible disposal sites, the design of potential disposal site studies of ecological resources, the preparation of the environmental report, and the regulatory review of license applications. 3 figures, 3 tables

Identification of local myocardial repolarization time by bipolar electrode potential.

Science.gov (United States)

Namba, Tsunetoyo; Todo, Takahiro; Yao, Takenori; Ashihara, Takashi; Haraguchi, Ryo; Nakazawa, Kazuo; Ikeda, Takanori; Ohe, Tohru

2007-01-01

The aim of this study was to investigate whether bipolar electrode potentials (BEPs) reflect local myocardial repolarization dynamics, using computer simulation. Simulated action potential and BEP mapping of myocardial tissue during fibrillation was performed. The BEP was modified to make all the fluctuations have the same polarity. Then, the modified BEP (mBEP) was transformed to "dynamic relative amplitude" (DRA) designed to make all the fluctuations have the similar amplitude. The repolarization end point corresponded to the end of the repolarization-related small fluctuation that clearly appeared in the DRA of mBEP. Using the DRA of mBEP, we could reproduce the repolarization dynamics in the myocardial tissue during fibrillation. The BEP may facilitate identifying the repolarization time. Furthermore, BEP mapping has the possibility that it would be available for evaluating repolarization behavior in myocardial tissue even during fibrillation. The accuracy of activation-recovery interval was also reconfirmed.

Storage of energies - Translating potential into actions

International Nuclear Information System (INIS)

Signoret, Stephane; Mary, Olivier; Petitot, Pauline; Dejeu, Mathieu; De Santis, Audrey

2015-01-01

In this set of articles, a first one evokes issues discussed during a colloquium held in Paris by the European association for storage of energy, the possibilities mentioned about energy storage development in the French bill project for energy transition, and the importance of non-interconnected areas in the development of energy storage. A second article proposes an overview of developments and advances in energy storage in California which adopted suitable laws. The German situation is then briefly described: needs are still to be defined and a road map has been published in 2014, as technologies are expensive and the legal framework is still complex. The next article outlines the conditions of development of the power-to-gas sector (as a process of valorisation of excess electricity). An article gives an overview of technological developments in the field of electrochemical energy storage (batteries). The results of the PEPS study (a study on the potential of energy storage) in Europe are commented. An interview with a member of the French BRGM (Bureau of Mines) outlines the major role which underground storage could play in energy transition. The Seti project for an intelligent thermal energy storage and a better use of renewable energies is then presented. An article comments how to use foodstuff cold to make consumption cut-offs. A last article comments how superconductors could be used in the future for batteries. Few examples are briefly presented: a molten salt-based storage by Areva, a local production of green hydrogen in France, an innovating project of solar energy storage in Switzerland, and the Toucan solar plant in French Guyana

Biphasic response of action potential duration to metabolic inhibition in rabbit and human ventricular myocytes: role of transient outward current and ATP-regulated potassium current

NARCIS (Netherlands)

Verkerk, A. O.; Veldkamp, M. W.; van Ginneken, A. C.; Bouman, L. N.

1996-01-01

Inhibition of cell metabolism is associated with significant changes in action potential duration. The aim of this study was to investigate the time course of the changes in action potential duration during metabolic inhibition and to determine what changes in membrane currents are responsible. The

Neural Behavior Chain Learning of Mobile Robot Actions

Directory of Open Access Journals (Sweden)

Lejla Banjanovic-Mehmedovic

2012-01-01

Full Text Available This paper presents a visual/motor behavior learning approach, based on neural networks. We propose Behavior Chain Model (BCM in order to create a way of behavior learning. Our behavior-based system evolution task is a mobile robot detecting a target and driving/acting towards it. First, the mapping relations between the image feature domain of the object and the robot action domain are derived. Second, a multilayer neural network for offline learning of the mapping relations is used. This learning structure through neural network training process represents a connection between the visual perceptions and motor sequence of actions in order to grip a target. Last, using behavior learning through a noticed action chain, we can predict mobile robot behavior for a variety of similar tasks in similar environment. Prediction results suggest that the methodology is adequate and could be recognized as an idea for designing different mobile robot behaviour assistance.

Analytical description of critical dynamics for two-dimensional dissipative nonlinear maps

International Nuclear Information System (INIS)

Méndez-Bermúdez, J.A.; Oliveira, Juliano A. de; Leonel, Edson D.

2016-01-01

The critical dynamics near the transition from unlimited to limited action diffusion for two families of well known dissipative nonlinear maps, namely the dissipative standard and dissipative discontinuous maps, is characterized by the use of an analytical approach. The approach is applied to explicitly obtain the average squared action as a function of the (discrete) time and the parameters controlling nonlinearity and dissipation. This allows to obtain a set of critical exponents so far obtained numerically in the literature. The theoretical predictions are verified by extensive numerical simulations. We conclude that all possible dynamical cases, independently on the map parameter values and initial conditions, collapse into the universal exponential decay of the properly normalized average squared action as a function of a normalized time. The formalism developed here can be extended to many other different types of mappings therefore making the methodology generic and robust. - Highlights: • We analytically approach scaling properties of a family of two-dimensional dissipative nonlinear maps. • We derive universal scaling functions that were obtained before only approximately. • We predict the unexpected condition where diffusion and dissipation compensate each other exactly. • We find a new universal scaling function that embraces all possible dissipative behaviors.

On the influence of reward on action-effect binding

Directory of Open Access Journals (Sweden)

Paul Simon Muhle-Karbe

2012-11-01

Full Text Available Ideomotor theory states that the formation of anticipatory representations about the perceptual consequences of an action (i.e. action-effect (A-E binding provides the functional basis of voluntary action control. A host of studies has demonstrated that A-E binding occurs fast and effortlessly, yet only little is known about cognitive and affective factors that influence this learning process. In the present study, we sought to test whether the motivational value of an action modulates the acquisition of A-E associations. To this end, we associated specific actions with monetary incentives during the acquisition of novel A-E mappings. In a subsequent test phase, the degree of binding was assessed by presenting the former effect stimuli as task-irrelevant response primes in a forced-choice response task in the absence of any reward. Binding, as indexed by response priming through the former action effects, was only found for reward-related A-E mappings. Moreover, the degree to which reward associations modulated the binding strength was predicted by individuals’ trait sensitivity to reward. These observations indicate that the association of actions and their immediate outcomes depends on the motivational value of the action during learning, as well as on the motivational disposition of the individual. On a larger scale, these findings also highlight the link between ideomotor theories and reinforcement-learning theories, providing an interesting perspective for future research on anticipatory regulation of behavior.

Performing Mimetic Mapping: A Non-Visualisable Map of the Suzhou River Area of Shanghai

Directory of Open Access Journals (Sweden)

Anastasia Karandinou

2014-07-01

Full Text Available This paper questions issues concerning the mapping of experience, through the concept of mimesis – the creative re-performance of the site experience onto the map. The place mapped is the Suzhou River area, a significant part of Shanghai, the former boundary between the British and American Settlements, and an ever-changing and transforming territory. Through the detailed description of the mapping processes, we analyse the position of this particular map within contemporary discourse about mapping. Here, we question the purpose of the process, the desired outcome, the consciousness of the significance of each step/event, and the possible significance of the final traces that the mapping leaves behind. Although after the mapping had been carried out, the procedure was analysed, post-rationalised, and justified through its partial documentation (as part of an educational process, this paper questions the way and the reason for these practices (the post-rationalising of the mapping activity, justifying the strategy, etc., and their possible meaning, purpose, demand or context. Thus we conclude that the subject matter is not the final outcome of an object or ‘map’; there is no final map to be exhibited. What this paper brings forth is the mapping as an event, an action performed by the embodied experience of the actual place and by the trans-local materiality of the tools and elements involved in the process of its making.

Potential of Pest and Host Phenological Data in the Attribution of Regional Forest Disturbance Detection Maps According to Causal Agent

Science.gov (United States)

Spruce, Joseph; Hargrove, William; Norman Steve; Christie, William

2014-01-01

Near real time forest disturbance detection maps from MODIS NDVI phenology data have been produced since 2010 for the conterminous U.S., as part of the on-line ForWarn national forest threat early warning system. The latter has been used by the forest health community to identify and track many regional forest disturbances caused by multiple biotic and abiotic damage agents. Attribution of causal agents for detected disturbances has been a goal since project initiation in 2006. Combined with detailed cover type maps, geospatial pest phenology data offer a potential means for narrowing the candidate causal agents responsible for a given biotic disturbance. U.S. Aerial Detection Surveys (ADS) employ such phenology data. Historic ADS products provide general locational data on recent insect-induced forest type specific disturbances that may help in determining candidate causal agents for MODIS-based disturbance maps, especially when combined with other historic geospatial disturbance data (e.g., wildfire burn scars and drought maps). Historic ADS disturbance detection polygons can show severe and extensive regional forest disturbances, though they also can show polygons with sparsely scattered or infrequent disturbances. Examples will be discussed that use various historic disturbance data to help determine potential causes of MODIS-detected regional forest disturbance anomalies.

Prediction of Thorough QT study results using action potential simulations based on ion channel screens.

Science.gov (United States)

Mirams, Gary R; Davies, Mark R; Brough, Stephen J; Bridgland-Taylor, Matthew H; Cui, Yi; Gavaghan, David J; Abi-Gerges, Najah

2014-01-01

Detection of drug-induced pro-arrhythmic risk is a primary concern for pharmaceutical companies and regulators. Increased risk is linked to prolongation of the QT interval on the body surface ECG. Recent studies have shown that multiple ion channel interactions can be required to predict changes in ventricular repolarisation and therefore QT intervals. In this study we attempt to predict the result of the human clinical Thorough QT (TQT) study, using multiple ion channel screening which is available early in drug development. Ion current reduction was measured, in the presence of marketed drugs which have had a TQT study, for channels encoded by hERG, CaV1.2, NaV1.5, KCNQ1/MinK, and Kv4.3/KChIP2.2. The screen was performed on two platforms - IonWorks Quattro (all 5 channels, 34 compounds), and IonWorks Barracuda (hERG & CaV1.2, 26 compounds). Concentration-effect curves were fitted to the resulting data, and used to calculate a percentage reduction in each current at a given concentration. Action potential simulations were then performed using the ten Tusscher and Panfilov (2006), Grandi et al. (2010) and O'Hara et al. (2011) human ventricular action potential models, pacing at 1Hz and running to steady state, for a range of concentrations. We compared simulated action potential duration predictions with the QT prolongation observed in the TQT studies. At the estimated concentrations, simulations tended to underestimate any observed QT prolongation. When considering a wider range of concentrations, and conventional patch clamp rather than screening data for hERG, prolongation of ≥5ms was predicted with up to 79% sensitivity and 100% specificity. This study provides a proof-of-principle for the prediction of human TQT study results using data available early in drug development. We highlight a number of areas that need refinement to improve the method's predictive power, but the results suggest that such approaches will provide a useful tool in cardiac safety

Evaluation of Logistic Regression and Multivariate Adaptive Regression Spline Models for Groundwater Potential Mapping Using R and GIS

Directory of Open Access Journals (Sweden)

Soyoung Park

2017-07-01

Full Text Available This study mapped and analyzed groundwater potential using two different models, logistic regression (LR and multivariate adaptive regression splines (MARS, and compared the results. A spatial database was constructed for groundwater well data and groundwater influence factors. Groundwater well data with a high potential yield of ≥70 m3/d were extracted, and 859 locations (70% were used for model training, whereas the other 365 locations (30% were used for model validation. We analyzed 16 groundwater influence factors including altitude, slope degree, slope aspect, plan curvature, profile curvature, topographic wetness index, stream power index, sediment transport index, distance from drainage, drainage density, lithology, distance from fault, fault density, distance from lineament, lineament density, and land cover. Groundwater potential maps (GPMs were constructed using LR and MARS models and tested using a receiver operating characteristics curve. Based on this analysis, the area under the curve (AUC for the success rate curve of GPMs created using the MARS and LR models was 0.867 and 0.838, and the AUC for the prediction rate curve was 0.836 and 0.801, respectively. This implies that the MARS model is useful and effective for groundwater potential analysis in the study area.

Low- and intermediate level radioactive waste from Risoe, Denmark. Location studies for potential disposal areas. Report no. 1. Data, maps, models and methods used for selection of potential areas

Energy Technology Data Exchange (ETDEWEB)

Gravesen, P.; Nilsson, B.; Schack Pedersen, S.A.; Binderup, M.

2011-07-01

The low and intermediate level radioactive waste from Risoe (the nuclear reactor buildings plus different types of material from the research periods) and radioactive waste from hospitals and research institutes have to be stored in a final disposal in Denmark for at least 300 years. The Minister for Health and Prevention presented the background and decision plan for the Danish Parliament in January 2009. All political parties agreed on the plan. The investigation of geological deposits as potential waste disposals for high radioactive waste from nuclear power plants has earlier focused on deep seated salt deposits and basement rocks. Nevertheless, the Tertiary clays were mapped as well. In the present study, the salt diapirs and the salt deposits are not included. The present report briefly describes the existing data collections (including databases, maps and models), that are used during the work of selection of ca. 20 potentially suitable areas. Most of the information is stored in GEUS databases: Location of boreholes, borehole data, rock sediment and ground water compounds, maps, geophysical data and much more, but information is also collected from other institutions. The methods are described in more details (chapter 6) and this description is the direct background for the selection process, the characterisation of the 20 areas and for the final selection of the 2 or 3 most potential sites. (LN)

Low- and intermediate level radioactive waste from Risoe, Denmark. Location studies for potential disposal areas. Report no. 1. Data, maps, models and methods used for selection of potential areas

International Nuclear Information System (INIS)

Gravesen, P.; Nilsson, B.; Schack Pedersen, S.A.; Binderup, M.

2011-01-01

The low and intermediate level radioactive waste from Risoe (the nuclear reactor buildings plus different types of material from the research periods) and radioactive waste from hospitals and research institutes have to be stored in a final disposal in Denmark for at least 300 years. The Minister for Health and Prevention presented the background and decision plan for the Danish Parliament in January 2009. All political parties agreed on the plan. The investigation of geological deposits as potential waste disposals for high radioactive waste from nuclear power plants has earlier focused on deep seated salt deposits and basement rocks. Nevertheless, the Tertiary clays were mapped as well. In the present study, the salt diapirs and the salt deposits are not included. The present report briefly describes the existing data collections (including databases, maps and models), that are used during the work of selection of ca. 20 potentially suitable areas. Most of the information is stored in GEUS databases: Location of boreholes, borehole data, rock sediment and ground water compounds, maps, geophysical data and much more, but information is also collected from other institutions. The methods are described in more details (chapter 6) and this description is the direct background for the selection process, the characterisation of the 20 areas and for the final selection of the 2 or 3 most potential sites. (LN)

Nanoelectronics-biology frontier: From nanoscopic probes for action potential recording in live cells to three-dimensional cyborg tissues

OpenAIRE

Duan, Xiaojie; Fu, Tian-Ming; Liu, Jia; Lieber, Charles M.

2013-01-01

Semiconductor nanowires configured as the active channels of field-effect transistors (FETs) have been used as detectors for high-resolution electrical recording from single live cells, cell networks, tissues and organs. Extracellular measurements with substrate supported silicon nanowire (SiNW) FETs, which have projected active areas orders of magnitude smaller than conventional microfabricated multielectrode arrays (MEAs) and planar FETs, recorded action potential and field potential signa...

Electrophysiological properties of computational human ventricular cell action potential models under acute ischemic conditions.

Science.gov (United States)

Dutta, Sara; Mincholé, Ana; Quinn, T Alexander; Rodriguez, Blanca

2017-10-01

Acute myocardial ischemia is one of the main causes of sudden cardiac death. The mechanisms have been investigated primarily in experimental and computational studies using different animal species, but human studies remain scarce. In this study, we assess the ability of four human ventricular action potential models (ten Tusscher and Panfilov, 2006; Grandi et al., 2010; Carro et al., 2011; O'Hara et al., 2011) to simulate key electrophysiological consequences of acute myocardial ischemia in single cell and tissue simulations. We specifically focus on evaluating the effect of extracellular potassium concentration and activation of the ATP-sensitive inward-rectifying potassium current on action potential duration, post-repolarization refractoriness, and conduction velocity, as the most critical factors in determining reentry vulnerability during ischemia. Our results show that the Grandi and O'Hara models required modifications to reproduce expected ischemic changes, specifically modifying the intracellular potassium concentration in the Grandi model and the sodium current in the O'Hara model. With these modifications, the four human ventricular cell AP models analyzed in this study reproduce the electrophysiological alterations in repolarization, refractoriness, and conduction velocity caused by acute myocardial ischemia. However, quantitative differences are observed between the models and overall, the ten Tusscher and modified O'Hara models show closest agreement to experimental data. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Feature-Specific Event-Related Potential Effects to Action- and Sound-Related Verbs during Visual Word Recognition.

Science.gov (United States)

Popp, Margot; Trumpp, Natalie M; Kiefer, Markus

2016-01-01

Grounded cognition theories suggest that conceptual representations essentially depend on modality-specific sensory and motor systems. Feature-specific brain activation across different feature types such as action or audition has been intensively investigated in nouns, while feature-specific conceptual category differences in verbs mainly focused on body part specific effects. The present work aimed at assessing whether feature-specific event-related potential (ERP) differences between action and sound concepts, as previously observed in nouns, can also be found within the word class of verbs. In Experiment 1, participants were visually presented with carefully matched sound and action verbs within a lexical decision task, which provides implicit access to word meaning and minimizes strategic access to semantic word features. Experiment 2 tested whether pre-activating the verb concept in a context phase, in which the verb is presented with a related context noun, modulates subsequent feature-specific action vs. sound verb processing within the lexical decision task. In Experiment 1, ERP analyses revealed a differential ERP polarity pattern for action and sound verbs at parietal and central electrodes similar to previous results in nouns. Pre-activation of the meaning of verbs in the preceding context phase in Experiment 2 resulted in a polarity-reversal of feature-specific ERP effects in the lexical decision task compared with Experiment 1. This parallels analogous earlier findings for primed action and sound related nouns. In line with grounded cognitions theories, our ERP study provides evidence for a differential processing of action and sound verbs similar to earlier observation for concrete nouns. Although the localizational value of ERPs must be viewed with caution, our results indicate that the meaning of verbs is linked to different neural circuits depending on conceptual feature relevance.

Boron-doped nanocrystalline diamond microelectrode arrays monitor cardiac action potentials.

Science.gov (United States)

Maybeck, Vanessa; Edgington, Robert; Bongrain, Alexandre; Welch, Joseph O; Scorsone, Emanuel; Bergonzo, Philippe; Jackman, Richard B; Offenhäusser, Andreas

2014-02-01

The expansion of diamond-based electronics in the area of biological interfacing has not been as thoroughly explored as applications in electrochemical sensing. However, the biocompatibility of diamond, large safe electrochemical window, stability, and tunable electronic properties provide opportunities to develop new devices for interfacing with electrogenic cells. Here, the fabrication of microelectrode arrays (MEAs) with boron-doped nanocrystalline diamond (BNCD) electrodes and their interfacing with cardiomyocyte-like HL-1 cells to detect cardiac action potentials are presented. A nonreductive means of structuring doped and undoped diamond on the same substrate is shown. The resulting BNCD electrodes show high stability under mechanical stress generated by the cells. It is shown that by fabricating the entire surface of the MEA with NCD, in patterns of conductive doped, and isolating undoped regions, signal detection may be improved up to four-fold over BNCD electrodes passivated with traditional isolators. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Crime Mapping and Geographical Information Systems in Crime Analysis

OpenAIRE

Dağlar, Murat; Argun, Uğur

2016-01-01

As essential apparatus in crime analysis, crime mapping and Geographical Information Systems (GIS) are being progressively more accepted by police agencies. Development in technology and the accessibility of geographic data sources make it feasible for police departments to use GIS and crime mapping. GIS and crime mapping can be utilized as devices to discover reasons contributing to crime, and hence let law enforcement agencies proactively take action against the crime problems before they b...

Climate Ready Estuaries Partner Projects Map

Science.gov (United States)

CRE partners with the National Estuary Program to develop climate change projects in coastal U.S. areas, such as bays and harbors; to develop adaptation action plans, identify climate impacts and indicators, and more. This map shows project locations.

Action Potential Modulation of Neural Spin Networks Suggests Possible Role of Spin

CERN Document Server

Hu, H P

2004-01-01

In this paper we show that nuclear spin networks in neural membranes are modulated by action potentials through J-coupling, dipolar coupling and chemical shielding tensors and perturbed by microscopically strong and fluctuating internal magnetic fields produced largely by paramagnetic oxygen. We suggest that these spin networks could be involved in brain functions since said modulation inputs information carried by the neural spike trains into them, said perturbation activates various dynamics within them and the combination of the two likely produce stochastic resonance thus synchronizing said dynamics to the neural firings. Although quantum coherence is desirable and may indeed exist, it is not required for these spin networks to serve as the subatomic components for the conventional neural networks.

Mapping of groundwater radon potential

International Nuclear Information System (INIS)

Aekerblom, G.; Lindgren, J.

1997-01-01

The domestic use of water with elevated radon concentration may represent a public health hazard, partly due to the release of radon to the indoor air. While only a limited number of countries have implemented regulations with respect to radon in water, many more are considering doing so. The compulsory limits proposed by Swedish authorities are 100 Bq/1 for public water, while water from private wells is not to exceed 1000 Bq/1. Furthermore, it is recommended that water with a radon content above 500 Bq/1 should not be given to children under five years of age. In Sweden, the estimated number of wells with radon levels above 1000 Bq/1 exceeds 10,000, with a considerable amount in excess of 10,000 Bq/1. The highest radon concentration in a well supplying drinking water encountered so far is 57,000 Bq/1. Radon levels exceeding 500 Bq/1 are almost exclusively found in wells drilled into bedrock and in springs with intramontaneous water. Elevated ground water radon levels require that the water has passed through bedrock with elevated concentration of uranium, or through fractures with coatings of minerals containing enhanced concentrations of radium-226. Intramontaneous water from areas with uranium-bearing rock types (e.g. uranium-rich granites, pegmatites and vulcanites) often manifests elevated radon levels. Routines for the establishment of risk maps focusing on water are currently under development. The backbone of the process is the access to high spatial resolution radiometric information together with bedrock and soil information on a detailed scale (1:50,000). This information is available from the Geological Survey of Sweden, which is routinely carrying out airborne measurements at an altitude of 30 m and a line spacing of 200 m. While some 60% of Sweden is covered up to now, 75 % is expected to be covered within the next ten years. Other available databases utilized in the risk mapping process include radon measurements in wells, geochemical data from

Singularity theory and equivariant symplectic maps

CERN Document Server

Bridges, Thomas J

1993-01-01

The monograph is a study of the local bifurcations of multiparameter symplectic maps of arbitrary dimension in the neighborhood of a fixed point.The problem is reduced to a study of critical points of an equivariant gradient bifurcation problem, using the correspondence between orbits ofa symplectic map and critical points of an action functional. New results onsingularity theory for equivariant gradient bifurcation problems are obtained and then used to classify singularities of bifurcating period-q points. Of particular interest is that a general framework for analyzing group-theoretic aspects and singularities of symplectic maps (particularly period-q points) is presented. Topics include: bifurcations when the symplectic map has spatial symmetry and a theory for the collision of multipliers near rational points with and without spatial symmetry. The monograph also includes 11 self-contained appendices each with a basic result on symplectic maps. The monograph will appeal to researchers and graduate student...

Mapping of soil organic carbon stocks for spatially explicit assessments of climate change mitigation potential

International Nuclear Information System (INIS)

Vågen, Tor-Gunnar; Winowiecki, Leigh A

2013-01-01

Current methods for assessing soil organic carbon (SOC) stocks are generally not well suited for understanding variations in SOC stocks in landscapes. This is due to the tedious and time-consuming nature of the sampling methods most commonly used to collect bulk density cores, which limits repeatability across large areas, particularly where information is needed on the spatial dynamics of SOC stocks at scales relevant to management and for spatially explicit targeting of climate change mitigation options. In the current study, approaches were explored for (i) field-based estimates of SOC stocks and (ii) mapping of SOC stocks at moderate to high resolution on the basis of data from four widely contrasting ecosystems in East Africa. Estimated SOC stocks for 0–30 cm depth varied both within and between sites, with site averages ranging from 2 to 8 kg m −2 . The differences in SOC stocks were determined in part by rainfall, but more importantly by sand content. Results also indicate that managing soil erosion is a key strategy for reducing SOC loss and hence in mitigation of climate change in these landscapes. Further, maps were developed on the basis of satellite image reflectance data with multiple R-squared values of 0.65 for the independent validation data set, showing variations in SOC stocks across these landscapes. These maps allow for spatially explicit targeting of potential climate change mitigation efforts through soil carbon sequestration, which is one option for climate change mitigation and adaptation. Further, the maps can be used to monitor the impacts of such mitigation efforts over time. (letter)

The Mapping X-ray Fluorescence Spectrometer (MapX)

Science.gov (United States)

Sarrazin, P.; Blake, D. F.; Marchis, F.; Bristow, T.; Thompson, K.

2017-12-01

Many planetary surface processes leave traces of their actions as features in the size range 10s to 100s of microns. The Mapping X-ray Fluorescence Spectrometer (MapX) will provide elemental imaging at 100 micron spatial resolution, yielding elemental chemistry at a scale where many relict physical, chemical, or biological features can be imaged and interpreted in ancient rocks on planetary bodies and planetesimals. MapX is an arm-based instrument positioned on a rock or regolith with touch sensors. During an analysis, an X-ray source (tube or radioisotope) bombards the sample with X-rays or alpha-particles / gamma-rays, resulting in sample X-ray Fluorescence (XRF). X-rays emitted in the direction of an X-ray sensitive CCD imager pass through a 1:1 focusing lens (X-ray micro-pore Optic (MPO)) that projects a spatially resolved image of the X-rays onto the CCD. The CCD is operated in single photon counting mode so that the energies and positions of individual X-ray photons are recorded. In a single analysis, several thousand frames are both stored and processed in real-time. Higher level data products include single-element maps with a lateral spatial resolution of 100 microns and quantitative XRF spectra from ground- or instrument- selected Regions of Interest (ROI). XRF spectra from ROI are compared with known rock and mineral compositions to extrapolate the data to rock types and putative mineralogies. When applied to airless bodies and implemented with an appropriate radioisotope source for alpha-particle excitation, MapX will be able to analyze biogenic elements C, N, O, P, S, in addition to the cations of the rock-forming elements >Na, accessible with either X-ray or gamma-ray excitation. The MapX concept has been demonstrated with a series of lab-based prototypes and is currently under refinement and TRL maturation.

Crown Fire Potential

Data.gov (United States)

Earth Data Analysis Center, University of New Mexico — Crown fire potential was modeled using FlamMap, an interagency fire behavior mapping and analysis program that computes potential fire behavior characteristics. The...

Dam-breach analysis and flood-inundation mapping for Lakes Ellsworth and Lawtonka near Lawton, Oklahoma

Science.gov (United States)

Rendon, Samuel H.; Ashworth, Chad E.; Smith, S. Jerrod

2012-01-01

Dams provide beneficial functions such as flood control, recreation, and reliable water supplies, but they also entail risk: dam breaches and resultant floods can cause substantial property damage and loss of life. The State of Oklahoma requires each owner of a high-hazard dam, which the Federal Emergency Management Agency defines as dams for which failure or misoperation probably will cause loss of human life, to develop an emergency action plan specific to that dam. Components of an emergency action plan are to simulate a flood resulting from a possible dam breach and map the resulting downstream flood-inundation areas. The resulting flood-inundation maps can provide valuable information to city officials, emergency managers, and local residents for planning the emergency response if a dam breach occurs. Accurate topographic data are vital for developing flood-inundation maps. This report presents results of a cooperative study by the city of Lawton, Oklahoma, and the U.S. Geological Survey (USGS) to model dam-breach scenarios at Lakes Ellsworth and Lawtonka near Lawton and to map the potential flood-inundation areas of such dam breaches. To assist the city of Lawton with completion of the emergency action plans for Lakes Ellsworth and Lawtonka Dams, the USGS collected light detection and ranging (lidar) data that were used to develop a high-resolution digital elevation model and a 1-foot contour elevation map for the flood plains downstream from Lakes Ellsworth and Lawtonka. This digital elevation model and field measurements, streamflow-gaging station data (USGS streamflow-gaging station 07311000, East Cache Creek near Walters, Okla.), and hydraulic values were used as inputs for the dynamic (unsteady-flow) model, Hydrologic Engineering Center's River Analysis System (HEC-RAS). The modeled flood elevations were exported to a geographic information system to produce flood-inundation maps. Water-surface profiles were developed for a 75-percent probable maximum

Mapping and Analysis of Forest and Land Fire Potential Using Geospatial Technology and Mathematical Modeling

International Nuclear Information System (INIS)

Suliman, M D H; Mahmud, M; Reba, M N M; S, L W

2014-01-01

Forest and land fire can cause negative implications for forest ecosystems, biodiversity, air quality and soil structure. However, the implications involved can be minimized through effective disaster management system. Effective disaster management mechanisms can be developed through appropriate early warning system as well as an efficient delivery system. This study tried to focus on two aspects, namely by mapping the potential of forest fire and land as well as the delivery of information to users through WebGIS application. Geospatial technology and mathematical modeling used in this study for identifying, classifying and mapping the potential area for burning. Mathematical models used is the Analytical Hierarchy Process (AHP), while Geospatial technologies involved include remote sensing, Geographic Information System (GIS) and digital field data collection. The entire Selangor state was chosen as our study area based on a number of cases have been reported over the last two decades. AHP modeling to assess the comparison between the three main criteria of fuel, topography and human factors design. Contributions of experts directly involved in forest fire fighting operations and land comprising officials from the Fire and Rescue Department Malaysia also evaluated in this model. The study found that about 32.83 square kilometers of the total area of Selangor state are the extreme potential for fire. Extreme potential areas identified are in Bestari Jaya and Kuala Langat High Ulu. Continuity of information and terrestrial forest fire potential was displayed in WebGIS applications on the internet. Display information through WebGIS applications is a better approach to help the decision-making process at a high level of confidence and approximate real conditions. Agencies involved in disaster management such as Jawatankuasa Pengurusan Dan Bantuan Bencana (JPBB) of District, State and the National under the National Security Division and the Fire and Rescue

Mapping and Analysis of Forest and Land Fire Potential Using Geospatial Technology and Mathematical Modeling

Science.gov (United States)

Suliman, M. D. H.; Mahmud, M.; Reba, M. N. M.; S, L. W.

2014-02-01

Forest and land fire can cause negative implications for forest ecosystems, biodiversity, air quality and soil structure. However, the implications involved can be minimized through effective disaster management system. Effective disaster management mechanisms can be developed through appropriate early warning system as well as an efficient delivery system. This study tried to focus on two aspects, namely by mapping the potential of forest fire and land as well as the delivery of information to users through WebGIS application. Geospatial technology and mathematical modeling used in this study for identifying, classifying and mapping the potential area for burning. Mathematical models used is the Analytical Hierarchy Process (AHP), while Geospatial technologies involved include remote sensing, Geographic Information System (GIS) and digital field data collection. The entire Selangor state was chosen as our study area based on a number of cases have been reported over the last two decades. AHP modeling to assess the comparison between the three main criteria of fuel, topography and human factors design. Contributions of experts directly involved in forest fire fighting operations and land comprising officials from the Fire and Rescue Department Malaysia also evaluated in this model. The study found that about 32.83 square kilometers of the total area of Selangor state are the extreme potential for fire. Extreme potential areas identified are in Bestari Jaya and Kuala Langat High Ulu. Continuity of information and terrestrial forest fire potential was displayed in WebGIS applications on the internet. Display information through WebGIS applications is a better approach to help the decision-making process at a high level of confidence and approximate real conditions. Agencies involved in disaster management such as Jawatankuasa Pengurusan Dan Bantuan Bencana (JPBB) of District, State and the National under the National Security Division and the Fire and Rescue

Efficient Temporal Action Localization in Videos

KAUST Repository

Alwassel, Humam

2018-01-01

as an application of the action spotting problem. Experiments on the THUMOS14 dataset reveal that our model is not only able to explore the video efficiently (observing on average 17.3% of the video) but it also accurately finds human activities with 30.8% mAP (0

Construction of symplectic full-turn maps by application of an arbitrary tracking code

International Nuclear Information System (INIS)

Warnock, R.L.

1989-03-01

A map to describe propagation of particles through any section of a nonlinear lattice may be represented as a Taylor expansion about the origin in phase space. Although the technique to compute the Taylor coefficients has been improved recently, the expansion may fail to provide adequate accuracy in regions where nonlinear effects are substantial. A representation of the map in angle-action coordinates, with the angle dependence given by a Fourier series, and the action dependence by polynomials in I/sup 1/2/, may be more successful. Maps of this form are easily constructed by taking Fourier transforms of results from an arbitrary symplectic tracking code. Examples are given of one-turn and two turn maps for the SLC North Damping Ring in a strongly nonlinear region. Results for accuracy and speed of evaluation of the maps are quite encouraging. It seems feasible to make accurate maps for the SSC by this method. 9 refs., 1 tab

Overexpression of the Large-Conductance, Ca2+-Activated K+ (BK) Channel Shortens Action Potential Duration in HL-1 Cardiomyocytes.

Science.gov (United States)

Stimers, Joseph R; Song, Li; Rusch, Nancy J; Rhee, Sung W

2015-01-01

Long QT syndrome is characterized by a prolongation of the interval between the Q wave and the T wave on the electrocardiogram. This abnormality reflects a prolongation of the ventricular action potential caused by a number of genetic mutations or a variety of drugs. Since effective treatments are unavailable, we explored the possibility of using cardiac expression of the large-conductance, Ca2+-activated K+ (BK) channel to shorten action potential duration (APD). We hypothesized that expression of the pore-forming α subunit of human BK channels (hBKα) in HL-1 cells would shorten action potential duration in this mouse atrial cell line. Expression of hBKα had minimal effects on expression levels of other ion channels with the exception of a small but significant reduction in Kv11.1. Patch-clamped hBKα expressing HL-1 cells exhibited an outward voltage- and Ca2+-sensitive K+ current, which was inhibited by the BK channel blocker iberiotoxin (100 nM). This BK current phenotype was not detected in untransfected HL-1 cells or in HL-1 null cells sham-transfected with an empty vector. Importantly, APD in hBKα-expressing HL-1 cells averaged 14.3 ± 2.8 ms (n = 10), which represented a 53% reduction in APD compared to HL-1 null cells lacking BKα expression. APD in the latter cells averaged 31.0 ± 5.1 ms (n = 13). The shortened APD in hBKα-expressing cells was restored to normal duration by 100 nM iberiotoxin, suggesting that a repolarizing K+ current attributed to BK channels accounted for action potential shortening. These findings provide initial proof-of-concept that the introduction of hBKα channels into a cardiac cell line can shorten APD, and raise the possibility that gene-based interventions to increase hBKα channels in cardiac cells may hold promise as a therapeutic strategy for long QT syndrome.

Critical Utopian Action Research

DEFF Research Database (Denmark)

Nielsen, Birger Steen; Nielsen, Kurt Aagaard

2016-01-01

The specific concept of critical utopian action research is presented and discussed, as to its origin, use and potentials. The inspiration from Robert Jungk and his future creating workshops is elaborated.......The specific concept of critical utopian action research is presented and discussed, as to its origin, use and potentials. The inspiration from Robert Jungk and his future creating workshops is elaborated....

ThermoMap. Interactive analysis and information system for the area-selected evaluation of the near-surface geothermal potential; ThermoMap. Interaktives Analyse- und Auskunftssystem zur flaechenhaften Abschaetzung des oberflaechennahen geothermischen Potenzials

Energy Technology Data Exchange (ETDEWEB)

Bertemann, David [Erlangen-Nuernberg Univ., Erlangen (DE). Lehrstuhl fuer Geologie (Exogene Dynamik); Psyk, Mario [REHAU AG and CO, Erlangen-Eltersdorf (Germany)

2012-07-01

The project ThermoMap funded by the European Commission enables a comprehensive assessment of the near-surface geothermal energy potential from already existing geoscientific data sets. Currently, twelve partners from nine EU Member States are involved.

Efficient Temporal Action Localization in Videos

KAUST Repository

Alwassel, Humam

2018-04-17

State-of-the-art temporal action detectors inefficiently search the entire video for specific actions. Despite the encouraging progress these methods achieve, it is crucial to design automated approaches that only explore parts of the video which are the most relevant to the actions being searched. To address this need, we propose the new problem of action spotting in videos, which we define as finding a specific action in a video while observing a small portion of that video. Inspired by the observation that humans are extremely efficient and accurate in spotting and finding action instances in a video, we propose Action Search, a novel Recurrent Neural Network approach that mimics the way humans spot actions. Moreover, to address the absence of data recording the behavior of human annotators, we put forward the Human Searches dataset, which compiles the search sequences employed by human annotators spotting actions in the AVA and THUMOS14 datasets. We consider temporal action localization as an application of the action spotting problem. Experiments on the THUMOS14 dataset reveal that our model is not only able to explore the video efficiently (observing on average 17.3% of the video) but it also accurately finds human activities with 30.8% mAP (0.5 tIoU), outperforming state-of-the-art methods

Potential use and challenges of functional connectivity mapping in intractable epilepsy

Directory of Open Access Journals (Sweden)

Robert Todd Constable

2013-05-01

Full Text Available This review focuses on the use of resting-state functional magnetic resonance imaging data to assess functional connectivity in the human brain for surgical planning in intractable epilepsy. This approach has the potential to predict outcomes for a given surgical procedure based on the pre-surgical functional organization of the brain. Functional connectivity can also identify cortical regions that are organized differently in epilepsy patients either as a direct function of the disease or through indirect compensatory responses. Functional connectivity mapping can also potentially help identify epileptogenic tissue, whether this is a single focal location or a network of seizure-generating tissues and this information can assist in guiding the implantation of electrodes for invasive monitoring. This review covers the basics of connectivity analysis and discusses particular issues associated with analyzing such data. These issues include how to define nodes, as well as differences between connectivity analyses of individual nodes, groups of nodes, and whole-brain assessment at the voxel level. The need for arbitrary thresholds in some connectivity analyses is discussed and a solution to this problem is reviewed. Overall, functional connectivity analysis is becoming an important tool for assessing functional brain organization in surgical planning in epilepsy.

Isosteviol prevents the prolongation of action potential in hypertrophied cardiomyoctyes by regulating transient outward potassium and L-type calcium channels.

Science.gov (United States)

Fan, Zhuo; Lv, Nanying; Luo, Xiao; Tan, Wen

2017-10-01

Cardiac hypertrophy is a thickening of the heart muscle that is associated with cardiovascular diseases such as hypertension and myocardial infarction. It occurs initially as an adaptive process against increased workloads and often leads to sudden arrhythmic deaths. Studies suggest that the lethal arrhythmia is attributed to hypertrophy-induced destabilization of cardiac electrical activity, especially the prolongation of the action potential. The reduced activity of I to is demonstrated to be responsible for the ionic mechanism of prolonged action potential duration and arrhythmogeneity. Isosteviol (STV), a derivative of stevioside, plays a protective role in a variety of stress-induced cardiac diseases. Here we report effects of STV on rat ISO-induced hypertrophic cardiomyocytes. STV alleviated ISO-induced hypertrophy of cardiomyocytes by decreasing cell area of hypertrophied cardiomyocytes. STV application prevented the prolongation of action potential which was prominent in hypertrophied cells. The decrease and increase of current densities for I to and I CaL observed in hypertrophied myocytes were both prevented by STV application. In addition, the results of qRT-PCR suggested that the changes of electrophysiological activity of I to and I CaL are correlated to the alterations of the mRNA transcription level. Copyright © 2017. Published by Elsevier B.V.

Effects of acoustic noise on the auditory nerve compound action potentials evoked by electric pulse trains.

Science.gov (United States)

Nourski, Kirill V; Abbas, Paul J; Miller, Charles A; Robinson, Barbara K; Jeng, Fuh-Cherng

2005-04-01

This study investigated the effects of acoustic noise on the auditory nerve compound action potentials in response to electric pulse trains. Subjects were adult guinea pigs, implanted with a minimally invasive electrode to preserve acoustic sensitivity. Electrically evoked compound action potentials (ECAP) were recorded from the auditory nerve trunk in response to electric pulse trains both during and after the presentation of acoustic white noise. Simultaneously presented acoustic noise produced a decrease in ECAP amplitude. The effect of the acoustic masker on the electric probe was greatest at the onset of the acoustic stimulus and it was followed by a partial recovery of the ECAP amplitude. Following cessation of the acoustic noise, ECAP amplitude recovered over a period of approximately 100-200 ms. The effects of the acoustic noise were more prominent at lower electric pulse rates (interpulse intervals of 3 ms and higher). At higher pulse rates, the ECAP adaptation to the electric pulse train alone was larger and the acoustic noise, when presented, produced little additional effect. The observed effects of noise on ECAP were the greatest at high electric stimulus levels and, for a particular electric stimulus level, at high acoustic noise levels.

Efficiency of preventive actions for landslides and flooding - evaluation of Scandinavian practices

Science.gov (United States)

Bergman, R.; Andersson-sköld, Y. B.; Nyberg, L.; Johansson, M.; Persson, E.

2011-12-01

Author: Ramona Bergman, Yvonne Andersson-Sköld, Lars Nyberg, Magnus Johansson, Erik Persson Preventive actions can be, and are frequently, taken to reduce accidents and their consequences in different ways. The MSB funded research programme "Effects of Society's Security actions" (ESS, 2009-2013) aims to study the relationship between such actions and their effects. The program is divided into three subgroups: Frequent accidents Natural hazards (such as flooding, erosion and landslide) Chemical and landfill accidents The results presented here covers natural hazards with focus on land slides and flooding. The results are based on Swedish/Scandinavian contexts. Natural events such as erosion, flooding and land slides are common, but the number of accidents (events causing severe negative impact) is rare. Therefore, in such analysis there is limited data and other information available which can be used for example in statistical analysis of actions and their effects. Instead, the analysis must be based on other information. Therefore, the analysis may have to include aspects that only can be assessed by scenario and "what-if" analyses. In this project the main method has been interviews with officials in Swedish municipalities and national agencies in Sweden and Norway. The two levels are chosen since policies are taken on national (or international) level, while the key actions and actors are on the municipal level. The interviews cover experiences and potential scenarios. In all municipalities, one politician and officials working with planning and rescue service have been interviewed. The study covers hazard and risk mapping, follow up of such maps, physical planning and lessons learned from previous events and activities. The final outcome of the research will be a review of what is found to be well functioning, identification of weak points and recommendations for the management of landslides, erosion and flooding. The present results indicate that hazard

Enhancing local action planning through quantitative flood risk analysis: a case study in Spain

Science.gov (United States)

Castillo-Rodríguez, Jesica Tamara; Escuder-Bueno, Ignacio; Perales-Momparler, Sara; Ramón Porta-Sancho, Juan

2016-07-01

This article presents a method to incorporate and promote quantitative risk analysis to support local action planning against flooding. The proposed approach aims to provide a framework for local flood risk analysis, combining hazard mapping with vulnerability data to quantify risk in terms of expected annual affected population, potential injuries, number of fatalities, and economic damages. Flood risk is estimated combining GIS data of loads, system response, and consequences and using event tree modelling for risk calculation. The study area is the city of Oliva, located on the eastern coast of Spain. Results from risk modelling have been used to inform local action planning and to assess the benefits of structural and non-structural risk reduction measures. Results show the potential impact on risk reduction of flood defences and improved warning communication schemes through local action planning: societal flood risk (in terms of annual expected affected population) would be reduced up to 51 % by combining both structural and non-structural measures. In addition, the effect of seasonal population variability is analysed (annual expected affected population ranges from 82 to 107 %, compared with the current situation, depending on occupancy rates in hotels and campsites). Results highlight the need for robust and standardized methods for urban flood risk analysis replicability at regional and national scale.

Molecular motions that shape the cardiac action potential: Insights from voltage clamp fluorometry.

Science.gov (United States)

Zhu, Wandi; Varga, Zoltan; Silva, Jonathan R

2016-01-01

Very recently, voltage-clamp fluorometry (VCF) protocols have been developed to observe the membrane proteins responsible for carrying the ventricular ionic currents that form the action potential (AP), including those carried by the cardiac Na(+) channel, NaV1.5, the L-type Ca(2+) channel, CaV1.2, the Na(+)/K(+) ATPase, and the rapid and slow components of the delayed rectifier, KV11.1 and KV7.1. This development is significant, because VCF enables simultaneous observation of ionic current kinetics with conformational changes occurring within specific channel domains. The ability gained from VCF, to connect nanoscale molecular movement to ion channel function has revealed how the voltage-sensing domains (VSDs) control ion flux through channel pores, mechanisms of post-translational regulation and the molecular pathology of inherited mutations. In the future, we expect that this data will be of great use for the creation of multi-scale computational AP models that explicitly represent ion channel conformations, connecting molecular, cell and tissue electrophysiology. Here, we review the VCF protocol, recent results, and discuss potential future developments, including potential use of these experimental findings to create novel computational models. Copyright © 2015 Elsevier Ltd. All rights reserved.

Modulation of KCNQ1 alternative splicing regulates cardiac IKs and action potential repolarization.

Science.gov (United States)

Lee, Hsiang-Chun; Rudy, Yoram; Po-Yuan, Phd; Sheu, Sheng-Hsiung; Chang, Jan-Gowth; Cui, Jianmin

2013-08-01

Slow delayed-rectifier potassium current (IKs) channels, made of the pore-forming KCNQ1 and auxiliary KCNE1 subunits, play a key role in determining action potential duration (APD) in cardiac myocytes. The consequences of drug-induced KCNQ1 splice alteration remain unknown. To study the modulation of KCNQ1 alternative splicing by amiloride and the consequent changes in IKs and action potentials (APs) in ventricular myocytes. Canine endocardial, midmyocardial, and epicardial ventricular myocytes were isolated. Levels of KCNQ1a and KCNQ1b as well as a series of splicing factors were quantified by using the reverse transcriptase-polymerase chain reaction and Western blot. The effect of amiloride-induced changes in the KCNQ1b/total KCNQ1 ratio on AP was measured by using whole-cell patch clamp with and without isoproterenol. With 50 μmol/L of amiloride for 6 hours, KCNQ1a at transcriptional and translational levels increased in midmyocardial myocytes but decreased in endo- and epicardial myocytes. Likewise, changes in splicing factors in midmyocardial were opposite to that in endo- and epicardial myocytes. In midmyocardial myocytes amiloride shortened APD and decreased isoproterenol-induced early afterdepolarizations significantly. The same amiloride-induced effects were demonstrated by using human ventricular myocyte model for AP simulations under beta-adrenergic stimulation. Moreover, amiloride reduced the transmural dispersion of repolarization in pseudo-electrocardiogram. Amiloride regulates IKs and APs with transmural differences and reduces arrhythmogenicity through the modulation of KCNQ1 splicing. We suggested that the modulation of KCNQ1 splicing may help prevent arrhythmia. Copyright © 2013 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Standard map in magnetized relativistic systems: fixed points and regular acceleration.

Science.gov (United States)

de Sousa, M C; Steffens, F M; Pakter, R; Rizzato, F B

2010-08-01

We investigate the concept of a standard map for the interaction of relativistic particles and electrostatic waves of arbitrary amplitudes, under the action of external magnetic fields. The map is adequate for physical settings where waves and particles interact impulsively, and allows for a series of analytical result to be exactly obtained. Unlike the traditional form of the standard map, the present map is nonlinear in the wave amplitude and displays a series of peculiar properties. Among these properties we discuss the relation involving fixed points of the maps and accelerator regimes.

Integrated assessment for establishing an oil environmental vulnerability map: case study for the Santos Basin region, Brazil.

Science.gov (United States)

Romero, A F; Abessa, D M S; Fontes, R F C; Silva, G H

2013-09-15

The growth of maritime transport and oil exploitation activities may increase the risk of oil spills. Thus, plans and actions to prevent or mitigate impacts are needed to minimize the effects caused by oil. However, tools used worldwide to support contingency plans have not been integrated, thus leading to failure in establishing priority areas. This investigation aimed to develop indices of environmental vulnerability to oil (IEVO), by combining information about environmental sensibility to oil and results of numerical modeling of spilled oil. To achieve that, a case study concerning to oil spills scenarios in a subtropical coastal area was designed, and IEVOs were calculated and presented in maps, in order to make the information about the areas' vulnerability more easily visualized. For summer, the extension of coastline potentially affected by oil was approximately 150 km, and most of the coastline presented medium to high vulnerability. For winter, 230 km coastline would be affected, from which 75% were classified as medium to high vulnerability. Thus, IEVO maps allowed a rapid and clearer interpretation of the vulnerability of the mapped region, facilitating the planning process and the actions in response to an oil spill. Copyright © 2013 Elsevier Ltd. All rights reserved.

Karst groundwater protection: First application of a Pan-European Approach to vulnerability, hazard and risk mapping in the Sierra de Libar (Southern Spain)

International Nuclear Information System (INIS)

Andreo, Bartolome; Goldscheider, Nico; Vadillo, Inaki; Vias, Jesus Maria; Neukum, Christoph; Sinreich, Michael; Jimenez, Pablo; Brechenmacher, Julia; Carrasco, Francisco; Hoetzl, Heinz; Perles, Maria Jesus; Zwahlen, Francois

2006-01-01

The European COST action 620 proposed a comprehensive approach to karst groundwater protection, comprising methods of intrinsic and specific vulnerability mapping, validation of vulnerability maps, hazard and risk mapping. This paper presents the first application of all components of this Pan-European Approach to the Sierra de Libar, a karst hydrogeology system in Andalusia, Spain. The intrinsic vulnerability maps take into account the hydrogeological characteristics of the area but are independent from specific contaminant properties. Two specific vulnerability maps were prepared for faecal coliforms and BTEX. These maps take into account the specific properties of these two groups of contaminants and their interaction with the karst hydrogeological system. The vulnerability assessment was validated by means of tracing tests, hydrological, hydrochemical and isotope methods. The hazard map shows the localization of potential contamination sources resulting from human activities, and evaluates those according to their dangerousness. The risk of groundwater contamination depends on the hazards and the vulnerability of the aquifer system. The risk map for the Sierra de Libar was thus created by overlaying the hazard and vulnerability maps

Karst groundwater protection: First application of a Pan-European Approach to vulnerability, hazard and risk mapping in the Sierra de Libar (Southern Spain)

Energy Technology Data Exchange (ETDEWEB)

Andreo, Bartolome [Group of Hydrogeology, Faculty of Science, University of Malaga, Campus de Teatinos, E-29071 Malaga (Spain)]. E-mail: Andreo@uma.es; Goldscheider, Nico [Centre of Hydrogeology, University of Neuchatel, 11 rue Emile-Argand, CH-2007 Neuchatel (Switzerland); Vadillo, Inaki [Group of Hydrogeology, Faculty of Science, University of Malaga, Campus de Teatinos, E-29071 Malaga (Spain); Vias, Jesus Maria [Group of Hydrogeology, Faculty of Science, University of Malaga, Campus de Teatinos, E-29071 Malaga (Spain); Neukum, Christoph [Department of Applied Geology, University of Karlsruhe, Kaiserstrasse, 12, D-76128 Karlsruhe (Germany); Sinreich, Michael [Centre of Hydrogeology, University of Neuchatel, 11 rue Emile-Argand, CH-2007 Neuchatel (Switzerland); Jimenez, Pablo [Group of Hydrogeology, Faculty of Science, University of Malaga, Campus de Teatinos, E-29071 Malaga (Spain); Brechenmacher, Julia [Department of Applied Geology, University of Karlsruhe, Kaiserstrasse, 12, D-76128 Karlsruhe (Germany); Carrasco, Francisco [Group of Hydrogeology, Faculty of Science, University of Malaga, Campus de Teatinos, E-29071 Malaga (Spain); Hoetzl, Heinz [Department of Applied Geology, University of Karlsruhe, Kaiserstrasse, 12, D-76128 Karlsruhe (Germany); Perles, Maria Jesus [Group of Hydrogeology, Faculty of Science, University of Malaga, Campus de Teatinos, E-29071 Malaga (Spain); Zwahlen, Francois [Centre of Hydrogeology, University of Neuchatel, 11 rue Emile-Argand, CH-2007 Neuchatel (Switzerland)

2006-03-15

The European COST action 620 proposed a comprehensive approach to karst groundwater protection, comprising methods of intrinsic and specific vulnerability mapping, validation of vulnerability maps, hazard and risk mapping. This paper presents the first application of all components of this Pan-European Approach to the Sierra de Libar, a karst hydrogeology system in Andalusia, Spain. The intrinsic vulnerability maps take into account the hydrogeological characteristics of the area but are independent from specific contaminant properties. Two specific vulnerability maps were prepared for faecal coliforms and BTEX. These maps take into account the specific properties of these two groups of contaminants and their interaction with the karst hydrogeological system. The vulnerability assessment was validated by means of tracing tests, hydrological, hydrochemical and isotope methods. The hazard map shows the localization of potential contamination sources resulting from human activities, and evaluates those according to their dangerousness. The risk of groundwater contamination depends on the hazards and the vulnerability of the aquifer system. The risk map for the Sierra de Libar was thus created by overlaying the hazard and vulnerability maps.

Talk and Action

DEFF Research Database (Denmark)

Christensen, Lars Thøger; Morsing, Mette; Thyssen, Ole

The aim of this paper is to analyze the relationship between organizational talk and action. Focusing in particular on the temporal dimension of this relationship, that is, the potential for talk to become action over time, we put forward ideal types of organizational strategies for possible talk...

The conceptual maps in the development of the course of biology of tenth degree: An investigation experience action in the classroom

Science.gov (United States)

Samo Goyco, Marisol

This investigation describes and combines the qualitative and quantitative methods of nature. The research I have work explore, observe, record and also it describes the experience to consider the education and teaching of the course. This investigation is a research that our students from the biology course, since the constructivist approach identifying and correct mistake. In this investigation there were participating twenty five students of tenth grade from a public school specialized in music. This research includes conceptual maps, computer integration, science programmed, internet, and broadcast and assessment approach. The research of conceptual maps establishes the correct method to perform capture the acknowledgement and attention of the investigators and the students which represents a significant relation between the concepts. Thought the investigator sustains on the cycle spiral of Carr and kemmis (1988) I design every unit considering the previous ideology of the student and elaborating the unit plan. Sustaining Maintain the methodology of the action research. The methodology has response to a new teaching paradigm. Situate as a principal assignment of the professor to contribute in the process of active learning to the students. Also helps to have in this process a reflection in their function or goals. During the research I analyze and wrote the observation and materials. The investigator express in her writing the final findings in every cycle. Also evaluates the map concepts the varied integration of activity and the assessment skills which are used through the socialized discussion. The socialized discussion communicates the participant concepts that should be attended. The students express between their peers and in front of the research of the investigator how they felt in terms of resources and the development of the maps. At the moment of this information I design the next cycle responding to the outstanding needs, this reflection genre a

Mapping the polysaccharide degradation potential of Aspergillus niger

Science.gov (United States)

2012-01-01

Background The degradation of plant materials by enzymes is an industry of increasing importance. For sustainable production of second generation biofuels and other products of industrial biotechnology, efficient degradation of non-edible plant polysaccharides such as hemicellulose is required. For each type of hemicellulose, a complex mixture of enzymes is required for complete conversion to fermentable monosaccharides. In plant-biomass degrading fungi, these enzymes are regulated and released by complex regulatory structures. In this study, we present a methodology for evaluating the potential of a given fungus for polysaccharide degradation. Results Through the compilation of information from 203 articles, we have systematized knowledge on the structure and degradation of 16 major types of plant polysaccharides to form a graphical overview. As a case example, we have combined this with a list of 188 genes coding for carbohydrate-active enzymes from Aspergillus niger, thus forming an analysis framework, which can be queried. Combination of this information network with gene expression analysis on mono- and polysaccharide substrates has allowed elucidation of concerted gene expression from this organism. One such example is the identification of a full set of extracellular polysaccharide-acting genes for the degradation of oat spelt xylan. Conclusions The mapping of plant polysaccharide structures along with the corresponding enzymatic activities is a powerful framework for expression analysis of carbohydrate-active enzymes. Applying this network-based approach, we provide the first genome-scale characterization of all genes coding for carbohydrate-active enzymes identified in A. niger. PMID:22799883

Effect of noise on the standard mapping

International Nuclear Information System (INIS)

Karney, C.F.F.; Rechester, A.B.; White, R.B.

1981-03-01

The effect of a small amount of noise on the standard mapping is considered. Whenever the standard mapping possesses accelerator models (where the action increases approximately linearly with time), the diffusion coefficient contains a term proportional to the reciprocal of the variance of the noise term. At large values of the stochasticity parameter, the accelerator modes exhibit a universal behavior. As a result the dependence of the diffusion coefficient on stochasticity parameter also shows some universal behavior

Mapping potential zones for groundwater recharge and its evaluation in arid environments using a GIS approach: Case study of North Gafsa Basin (Central Tunisia)

Science.gov (United States)

Mokadem, Naziha; Boughariou, Emna; Mudarra, Matías; Ben Brahim, Fatma; Andreo, Bartolome; Hamed, Younes; Bouri, Salem

2018-05-01

With the progressive evolution of industrial sector, agricultural, urbanization, population and drinking water supply, the water demand continuously increases which necessitates the planning of groundwater recharge particularly in arid and semi-arid regions. This paper gives a comprehensive review of various recharges studies in the North Gafsa basin (South Tunisia). This latter is characterized by a natural groundwater recharge that is deeply affected by the lack of precipitations. The aim of this study is to determine the recharge potential zones and to quantify (or estimate) the rainfall recharge of the shallow aquifers. The mapping of the potential recharge zones was established in North Gafsa basin, using geological and hydrological parameters such as slope, lithology, topography and stream network. Indeed, GIS provide tools to reclassify these input layers to produce the final map of groundwater potential zones of the study area. The final output map reveals two distinct zones representing moderate and low groundwater potential recharge. Recharge estimations were based on the four methods: (1) Chloride Method, (2) ERAS Method, (3) DGRE coefficient and (4) Fersi equations. Therefore, the overall results of the different methods demonstrate that the use of the DGRE method applying on the potential zones is more validated.

POLE PHOTOGRAMMETRY WITH AN ACTION CAMERA FOR FAST AND ACCURATE SURFACE MAPPING

Directory of Open Access Journals (Sweden)

J. A. Gonçalves

2016-06-01

Full Text Available High resolution and high accuracy terrain mapping can provide height change detection for studies of erosion, subsidence or land slip. A UAV flying at a low altitude above the ground, with a compact camera, acquires images with resolution appropriate for these change detections. However, there may be situations where different approaches may be needed, either because higher resolution is required or the operation of a drone is not possible. Pole photogrammetry, where a camera is mounted on a pole, pointing to the ground, is an alternative. This paper describes a very simple system of this kind, created for topographic change detection, based on an action camera. These cameras have high quality and very flexible image capture. Although radial distortion is normally high, it can be treated in an auto-calibration process. The system is composed by a light aluminium pole, 4 meters long, with a 12 megapixel GoPro camera. Average ground sampling distance at the image centre is 2.3 mm. The user moves along a path, taking successive photos, with a time lapse of 0.5 or 1 second, and adjusting the speed in order to have an appropriate overlap, with enough redundancy for 3D coordinate extraction. Marked ground control points are surveyed with GNSS for precise georeferencing of the DSM and orthoimage that are created by structure from motion processing software. An average vertical accuracy of 1 cm could be achieved, which is enough for many applications, for example for soil erosion. The GNSS survey in RTK mode with permanent stations is now very fast (5 seconds per point, which results, together with the image collection, in a very fast field work. If an improved accuracy is needed, since image resolution is 1/4 cm, it can be achieved using a total station for the control point survey, although the field work time increases.

Pole Photogrammetry with AN Action Camera for Fast and Accurate Surface Mapping

Science.gov (United States)

Gonçalves, J. A.; Moutinho, O. F.; Rodrigues, A. C.

2016-06-01

High resolution and high accuracy terrain mapping can provide height change detection for studies of erosion, subsidence or land slip. A UAV flying at a low altitude above the ground, with a compact camera, acquires images with resolution appropriate for these change detections. However, there may be situations where different approaches may be needed, either because higher resolution is required or the operation of a drone is not possible. Pole photogrammetry, where a camera is mounted on a pole, pointing to the ground, is an alternative. This paper describes a very simple system of this kind, created for topographic change detection, based on an action camera. These cameras have high quality and very flexible image capture. Although radial distortion is normally high, it can be treated in an auto-calibration process. The system is composed by a light aluminium pole, 4 meters long, with a 12 megapixel GoPro camera. Average ground sampling distance at the image centre is 2.3 mm. The user moves along a path, taking successive photos, with a time lapse of 0.5 or 1 second, and adjusting the speed in order to have an appropriate overlap, with enough redundancy for 3D coordinate extraction. Marked ground control points are surveyed with GNSS for precise georeferencing of the DSM and orthoimage that are created by structure from motion processing software. An average vertical accuracy of 1 cm could be achieved, which is enough for many applications, for example for soil erosion. The GNSS survey in RTK mode with permanent stations is now very fast (5 seconds per point), which results, together with the image collection, in a very fast field work. If an improved accuracy is needed, since image resolution is 1/4 cm, it can be achieved using a total station for the control point survey, although the field work time increases.

Application of optical action potentials in human induced pluripotent stem cells-derived cardiomyocytes to predict drug-induced cardiac arrhythmias.

Science.gov (United States)

Lu, H R; Hortigon-Vinagre, M P; Zamora, V; Kopljar, I; De Bondt, A; Gallacher, D J; Smith, G

2017-09-01

Human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) are emerging as new and human-relevant source in vitro model for cardiac safety assessment that allow us to investigate a set of 20 reference drugs for predicting cardiac arrhythmogenic liability using optical action potential (oAP) assay. Here, we describe our examination of the oAP measurement using a voltage sensitive dye (Di-4-ANEPPS) to predict adverse compound effects using hiPS-CMs and 20 cardioactive reference compounds. Fluorescence signals were digitized at 10kHz and the records subsequently analyzed off-line. Cells were exposed to 30min incubation to vehicle or compound (n=5/dose, 4 doses/compound) that were blinded to the investigating laboratory. Action potential parameters were measured, including rise time (T rise ) of the optical action potential duration (oAPD). Significant effects on oAPD were sensitively detected with 11 QT-prolonging drugs, while oAPD shortening was observed with I Ca -antagonists, I Kr -activator or ATP-sensitive K + channel (K ATP )-opener. Additionally, the assay detected varied effects induced by 6 different sodium channel blockers. The detection threshold for these drug effects was at or below the published values of free effective therapeutic plasma levels or effective concentrations by other studies. The results of this blinded study indicate that OAP is a sensitive method to accurately detect drug-induced effects (i.e., duration/QT-prolongation, shortening, beat rate, and incidence of early after depolarizations) in hiPS-CMs; therefore, this technique will potentially be useful in predicting drug-induced arrhythmogenic liabilities in early de-risking within the drug discovery phase. Copyright © 2017 Elsevier Inc. All rights reserved.

The Global Hidden Hunger Indices and Maps: An Advocacy Tool for Action

Science.gov (United States)

Muthayya, Sumithra; Rah, Jee Hyun; Sugimoto, Jonathan D.; Roos, Franz F.; Kraemer, Klaus; Black, Robert E.

2013-01-01

The unified global efforts to mitigate the high burden of vitamin and mineral deficiency, known as hidden hunger, in populations around the world are crucial to the achievement of most of the Millennium Development Goals (MDGs). We developed indices and maps of global hidden hunger to help prioritize program assistance, and to serve as an evidence-based global advocacy tool. Two types of hidden hunger indices and maps were created based on i) national prevalence data on stunting, anemia due to iron deficiency, and low serum retinol levels among preschool-aged children in 149 countries; and ii) estimates of Disability Adjusted Life Years (DALYs) attributed to micronutrient deficiencies in 136 countries. A number of countries in sub-Saharan Africa, as well as India and Afghanistan, had an alarmingly high level of hidden hunger, with stunting, iron deficiency anemia, and vitamin A deficiency all being highly prevalent. The total DALY rates per 100,000 population, attributed to micronutrient deficiencies, were generally the highest in sub-Saharan African countries. In 36 countries, home to 90% of the world’s stunted children, deficiencies of micronutrients were responsible for 1.5-12% of the total DALYs. The pattern and magnitude of iodine deficiency did not conform to that of other micronutrients. The greatest proportions of children with iodine deficiency were in the Eastern Mediterranean (46.6%), European (44.2%), and African (40.4%) regions. The current indices and maps provide crucial data to optimize the prioritization of program assistance addressing global multiple micronutrient deficiencies. Moreover, the indices and maps serve as a useful advocacy tool in the call for increased commitments to scale up effective nutrition interventions. PMID:23776712

The global hidden hunger indices and maps: an advocacy tool for action.

Science.gov (United States)

Muthayya, Sumithra; Rah, Jee Hyun; Sugimoto, Jonathan D; Roos, Franz F; Kraemer, Klaus; Black, Robert E

2013-01-01

The unified global efforts to mitigate the high burden of vitamin and mineral deficiency, known as hidden hunger, in populations around the world are crucial to the achievement of most of the Millennium Development Goals (MDGs). We developed indices and maps of global hidden hunger to help prioritize program assistance, and to serve as an evidence-based global advocacy tool. Two types of hidden hunger indices and maps were created based on i) national prevalence data on stunting, anemia due to iron deficiency, and low serum retinol levels among preschool-aged children in 149 countries; and ii) estimates of Disability Adjusted Life Years (DALYs) attributed to micronutrient deficiencies in 136 countries. A number of countries in sub-Saharan Africa, as well as India and Afghanistan, had an alarmingly high level of hidden hunger, with stunting, iron deficiency anemia, and vitamin A deficiency all being highly prevalent. The total DALY rates per 100,000 population, attributed to micronutrient deficiencies, were generally the highest in sub-Saharan African countries. In 36 countries, home to 90% of the world's stunted children, deficiencies of micronutrients were responsible for 1.5-12% of the total DALYs. The pattern and magnitude of iodine deficiency did not conform to that of other micronutrients. The greatest proportions of children with iodine deficiency were in the Eastern Mediterranean (46.6%), European (44.2%), and African (40.4%) regions. The current indices and maps provide crucial data to optimize the prioritization of program assistance addressing global multiple micronutrient deficiencies. Moreover, the indices and maps serve as a useful advocacy tool in the call for increased commitments to scale up effective nutrition interventions.

[Hardware Implementation of Numerical Simulation Function of Hodgkin-Huxley Model Neurons Action Potential Based on Field Programmable Gate Array].

Science.gov (United States)

Wang, Jinlong; Lu, Mai; Hu, Yanwen; Chen, Xiaoqiang; Pan, Qiangqiang

2015-12-01

Neuron is the basic unit of the biological neural system. The Hodgkin-Huxley (HH) model is one of the most realistic neuron models on the electrophysiological characteristic description of neuron. Hardware implementation of neuron could provide new research ideas to clinical treatment of spinal cord injury, bionics and artificial intelligence. Based on the HH model neuron and the DSP Builder technology, in the present study, a single HH model neuron hardware implementation was completed in Field Programmable Gate Array (FPGA). The neuron implemented in FPGA was stimulated by different types of current, the action potential response characteristics were analyzed, and the correlation coefficient between numerical simulation result and hardware implementation result were calculated. The results showed that neuronal action potential response of FPGA was highly consistent with numerical simulation result. This work lays the foundation for hardware implementation of neural network.

On the existence of star products on quotient spaces of linear Hamiltonian torus actions

DEFF Research Database (Denmark)

Herbig, Hans-Christian; Iyengar, Srikanth B.; Pflaum, Markus J.

2009-01-01

that the Koszul complex on the moment map of an effective linear Hamiltonian torus action is acyclic. We rephrase the nonpositivity condition of Arms and Gotay (Adv Math 79(1):43–103, 1990) for linear Hamiltonian torus actions. It follows that reduced spaces of such actions admit continuous star products....

The automated reference toolset: A soil-geomorphic ecological potential matching algorithm

Science.gov (United States)

Nauman, Travis; Duniway, Michael C.

2016-01-01

Ecological inventory and monitoring data need referential context for interpretation. Identification of appropriate reference areas of similar ecological potential for site comparison is demonstrated using a newly developed automated reference toolset (ART). Foundational to identification of reference areas was a soil map of particle size in the control section (PSCS), a theme in US Soil Taxonomy. A 30-m resolution PSCS map of the Colorado Plateau (366,000 km2) was created by interpolating ∼5000 field soil observations using a random forest model and a suite of raster environmental spatial layers representing topography, climate, general ecological community, and satellite imagery ratios. The PSCS map had overall out of bag accuracy of 61.8% (Kappa of 0.54, p < 0.0001), and an independent validation accuracy of 93.2% at a set of 356 field plots along the southern edge of Canyonlands National Park, Utah. The ART process was also tested at these plots, and matched plots with the same ecological sites (ESs) 67% of the time where sites fell within 2-km buffers of each other. These results show that the PSCS and ART have strong application for ecological monitoring and sampling design, as well as assessing impacts of disturbance and land management action using an ecological potential framework. Results also demonstrate that PSCS could be a key mapping layer for the USDA-NRCS provisional ES development initiative.

Mapping flood and flooding potential indices: a methodological approach to identifying areas susceptible to flood and flooding risk. Case study: the Prahova catchment (Romania)

Science.gov (United States)

Zaharia, Liliana; Costache, Romulus; Prăvălie, Remus; Ioana-Toroimac, Gabriela

2017-04-01

Given that floods continue to cause yearly significant worldwide human and material damages, flood risk mitigation is a key issue and a permanent challenge in developing policies and strategies at various spatial scales. Therefore, a basic phase is elaborating hazard and flood risk maps, documents which are an essential support for flood risk management. The aim of this paper is to develop an approach that allows for the identification of flash-flood and flood-prone susceptible areas based on computing and mapping of two indices: FFPI (Flash-Flood Potential Index) and FPI (Flooding Potential Index). These indices are obtained by integrating in a GIS environment several geographical variables which control runoff (in the case of the FFPI) and favour flooding (in the case of the FPI). The methodology was applied in the upper (mountainous) and middle (hilly) catchment of the Prahova River, a densely populated and socioeconomically well-developed area which has been affected repeatedly by water-related hazards over the past decades. The resulting maps showing the spatialization of the FFPI and FPI allow for the identification of areas with high susceptibility to flashfloods and flooding. This approach can provide useful mapped information, especially for areas (generally large) where there are no flood/hazard risk maps. Moreover, the FFPI and FPI maps can constitute a preliminary step for flood risk and vulnerability assessment.

Biophysical foundations for the study of the electrical excitability and action potential propagation in myocardium

International Nuclear Information System (INIS)

Suarez Antola, R.

1991-01-01

The electric current flow in the heterogeneous and anysotropic volume conductor of the myocardium is studied. The equations of bidomain theory are derived using an approach framed in the theory of averaged fields, introducing microscopic, mesoscopic and macroscopic spatial scales. However, the procedure, compatible with the histological and the anatomical details of the organ, is different from the multiple scale asymptotic expansions usually applied in homogeneization problems. A probabilistic approach framed in large numbers theorems is used to derive the equation for membrane ionic current from the stochastic activity of the channels at the microscopic level. An operational procedure suitable to define a sharp bidomain boundary from the fuzzy distribution of structural details and physical properties at the histological level is given. The problem of threshold is studied. The sizes and shapes of critical masses of cardiac cells that must be depolarized above threshold in order to produce a propagated action potential are determined by an approximate analytical procedure. The concept of family of threshold patterns for the emergence of action potentials in the heart is introduced. This concept is applied to discuss the conditions of emergence of ectopic focus. Analytical formulae are derived, for the time constant and the rheobase for electrical stimulation of the myocardium. These formulae are in good agreement with known experimental results. New experiments that could be done to confirm or reject them are suggested

Dual Axis Radiographic Hydrodynamic Test Facility mitigation action plan. Annual report for 1998

International Nuclear Information System (INIS)

Haagenstad, T.

1999-01-01

This Mitigation Action Plan Annual Report (MAPAR) has been prepared as part of implementing the Dual Axis Radiographic Hydrodynamic Test Facility (DARHT) Mitigation Action Plan (MAP) to protect workers, soils, water, and biotic and cultural resources in and around the facility

Dual Axis Radiographic Hydrodynamic Test Facility mitigation action plan. Annual report for 1998

Energy Technology Data Exchange (ETDEWEB)

Haagenstad, T.

1999-01-15

This Mitigation Action Plan Annual Report (MAPAR) has been prepared as part of implementing the Dual Axis Radiographic Hydrodynamic Test Facility (DARHT) Mitigation Action Plan (MAP) to protect workers, soils, water, and biotic and cultural resources in and around the facility.

Community Mapping in Action: Uncovering Resources and Assets for Young Children and Their Families

Science.gov (United States)

Ordonez-Jasis, Rosario; Myck-Wayne, Janice

2012-01-01

Community mapping is a promising practice that can assist early intervention/early childhood special education (EI/ECSE) professionals uncover the depth and diversity of community needs, resources, and learning opportunities, in the neighborhoods surrounding their schools. Community mapping is an inquiry-based method that situates learning in the…

Comprehensive personal RF-EMF exposure map and its potential use in epidemiological studies.

Science.gov (United States)

Gonzalez-Rubio, Jesus; Najera, Alberto; Arribas, Enrique

2016-08-01

In recent years, numerous epidemiological studies, which deal with the potential effects of mobile phone antennas on health, have almost exclusively focused on their distance to mobile phone base stations. Although it is known that this is not the best approach to the problem, this situation occurs due to the numerous difficulties when determining the personal exposure to the radiofrequency electromagnetic fields (RF-EMF). However, due to the rise of personal exposimeters, the evolution of spatial statistics, the development of geographical information systems and the use of powerful software, new alternatives are available to deal with these epidemiological studies and thus overcome the aforementioned difficulties. Using these tools, this paper presents a lattice map of personal RF-EMF exposure from exterior mobile phone base stations, covering the entire 110 administrative regions in the city of Albacete (Spain). For this purpose, we used a personal exposimeter, Satimo EME Spy 140 model, performing measurements every 4s The exposimeter was located inside the plastic basket of a bicycle, whose versatility permitted the access to all the zones of the city. Once the exposure map was prepared, its relation with the known antenna locations was studied. The 64 mobile telephone antennas of the city were also georeferenced; the randomness of both variables (exposure and antennas) were studied by means of the Moran's I test. Results showed that the distribution of the antennas follows a grouped pattern (pbased on the mean exposure values to RF-EMF in these sections. The displayed map would permit the execution of more accurate epidemiological studies, since it would be possible to compare the exposure measurements with the incidence data of a disease. Copyright © 2016 Elsevier Inc. All rights reserved.

The Potential of Unmanned Aerial Vehicle for Large Scale Mapping of Coastal Area

International Nuclear Information System (INIS)

Darwin, N; Ahmad, A; Zainon, O

2014-01-01

Many countries in the tropical region are covered with cloud for most of the time, hence, it is difficult to get clear images especially from high resolution satellite imagery. Aerial photogrammetry can be used but most of the time the cloud problem still exists. Today, this problem could be solved using a system known as unmanned aerial vehicle (UAV) where the aerial images can be acquired at low altitude and the system can fly under the cloud. The UAV system could be used in various applications including mapping coastal area. The UAV system is equipped with an autopilot system and automatic method known as autonomous flying that can be utilized for data acquisition. To achieve high resolution imagery, a compact digital camera of high resolution was used to acquire the aerial images at an altitude. In this study, the UAV system was employed to acquire aerial images of a coastal simulation model at low altitude. From the aerial images, photogrammetric image processing was executed to produce photogrammetric outputs such a digital elevation model (DEM), contour line and orthophoto. In this study, ground control point (GCP) and check point (CP) were established using conventional ground surveying method (i.e total station). The GCP is used for exterior orientation in photogrammetric processes and CP for accuracy assessment based on Root Mean Square Error (RMSE). From this study, it was found that the UAV system can be used for large scale mapping of coastal simulation model with accuracy at millimeter level. It is anticipated that the same system could be used for large scale mapping of real coastal area and produces good accuracy. Finally, the UAV system has great potential to be used for various applications that require accurate results or products at limited time and less man power

Acute effects of ethanol on action potential and intracellular Ca2+ transient in cardiac ventricular cells: a simulation study

Czech Academy of Sciences Publication Activity Database

Pásek, Michal; Bébarová, M.; Christé, G.; Šimurdová, M.; Šimurda, J.

2016-01-01

Roč. 54, č. 5 (2016), s. 753-762 ISSN 0140-0118 Institutional support: RVO:61388998 Keywords : ethanol * cardiomyocyte * action potential * rat ventricular cell model * human ventricular cell model Subject RIV: BO - Biophysics Impact factor: 1.916, year: 2016

The Belem Framework for Action: Harnessing the Power and Potential of Adult Learning and Education for a Viable Future

Science.gov (United States)

Adult Learning, 2012

2012-01-01

This article presents the Belem Framework for Action. This framework focuses on harnessing the power and potential of adult learning and education for a viable future. This framework begins with a preamble on adult education and towards lifelong learning.

The development and mapping of functional markers in Fragaria and their transferability and potential for mapping in other genera.

Science.gov (United States)

Sargent, D J; Rys, A; Nier, S; Simpson, D W; Tobutt, K R

2007-01-01

We have developed 46 primer pairs from exon sequences flanking polymorphic introns of 23 Fragaria gene sequences and one Malus sequence deposited in the EMBL database. Sequencing of a set of the PCR products amplified with the novel primer pairs in diploid Fragaria showed the products to be homologous to the sequences from which the primers were originally designed. By scoring the segregation of the 24 genes in two diploid Fragaria progenies FV x FN (F. vesca x F. nubicola F(2)) and 815 x 903BC (F. vesca x F. viridis BC(1)) 29 genetic loci at discrete positions on the seven linkage groups previously characterised could be mapped, bringing to 35 the total number of known function genes mapped in Fragaria. Twenty primer pairs, representing 14 genes, amplified a product of the expected size in both Malus and Prunus. To demonstrate the applicability of these gene-specific loci to comparative mapping in Rosaceae, five markers that displayed clear polymorphism between the parents of a Malus and a Prunus mapping population were selected. The markers were then scored and mapped in at least one of the two additional progenies.

Modeling intentional inhibition of actions

NARCIS (Netherlands)

Thilakarathne, D.J.; Treur, J.

2015-01-01

Inspired by cognitive and neurological literature on action ownership and action awareness, in this paper a computational cognitive model for intentional inhibition (i.e.; the capacity to voluntarily suspend or inhibit an action) is introduced. The interplay between (positive) potential selection of

Mapping the potential distribution of the invasive Red Shiner, Cyprinella lutrensis (Teleostei: Cyprinidae) across waterways of the conterminous United States

Science.gov (United States)

Poulos, Helen M.; Chernoff, Barry; Fuller, Pam L.; Butman, David

2012-01-01