WorldWideScience

Sample records for proxy redox stimulus

  1. Apatite: a new redox proxy for silicic magmas?

    Science.gov (United States)

    Miles, Andrew; Graham, Colin; Hawkesworth, Chris; Gillespie, Martin; Bromiley, Geoff; Hinton, Richard

    2015-04-01

    Petrology, 89, 226-38. [2] Miles, A.J., Graham, C.M., Hawkesworth, C.J., Gillespie, M.R., Hinton, R.W., 2014, Mn in apatite: A new redox proxy for silicic magmas?: Geochimica et Cosmochimica Acta v. 132, p. 101-119.

  2. The effects of metamorphism on iron mineralogy and the iron speciation redox proxy

    Science.gov (United States)

    Slotznick, Sarah P.; Eiler, John M.; Fischer, Woodward W.

    2018-03-01

    As the most abundant transition metal in the Earth's crust, iron is a key player in the planetary redox budget. Observations of iron minerals in the sedimentary record have been used to describe atmospheric and aqueous redox environments over the evolution of our planet; the most common method applied is iron speciation, a geochemical sequential extraction method in which proportions of different iron minerals are compared to calibrations from modern sediments to determine water-column redox state. Less is known about how this proxy records information through post-depositional processes, including diagenesis and metamorphism. To get insight into this, we examined how the iron mineral groups/pools (silicates, oxides, sulfides, etc.) and paleoredox proxy interpretations can be affected by known metamorphic processes. Well-known metamorphic reactions occurring in sub-chlorite to kyanite rocks are able to move iron between different iron pools along a range of proxy vectors, potentially affecting paleoredox results. To quantify the effect strength of these reactions, we examined mineralogical and geochemical data from two classic localities where Silurian-Devonian shales, sandstones, and carbonates deposited in a marine sedimentary basin with oxygenated seawater (based on global and local biological constraints) have been regionally metamorphosed from lower-greenschist facies to granulite facies: Waits River and Gile Mountain Formations, Vermont, USA and the Waterville and Sangerville-Vassalboro Formations, Maine, USA. Plotting iron speciation ratios determined for samples from these localities revealed apparent paleoredox conditions of the depositional water column spanning the entire range from oxic to ferruginous (anoxic) to euxinic (anoxic and sulfidic). Pyrrhotite formation in samples highlighted problems within the proxy as iron pool assignment required assumptions about metamorphic reactions and pyrrhotite's identification depended on the extraction techniques

  3. Uranium stable isotope fractionation in the Black Sea: Modern calibration of the 238U/235U paleo-redox proxy

    Science.gov (United States)

    Rolison, John M.; Stirling, Claudine H.; Middag, Rob; Rijkenberg, Micha J. A.

    2017-04-01

    by mass transport processes, and the modelled ε values may underestimate the true isotope enrichment factors. These new results for the Black Sea provide important constraints on the use of 238U/235U as a proxy of the redox state of ancient oceans.

  4. Heterogeneity of Cr in Mytilus edulis: Implications for the Cr isotope system as a paleo-redox proxy

    Science.gov (United States)

    Bruggmann, Sylvie; Klaebe, Robert; Frei, Robert

    2017-04-01

    Changes in 53Cr/52Cr (δ53Cr) values recorded by biogenic carbonates are emerging as a proxy for variations in the redox state of the Earth's oceans and atmosphere (e.g. [1], [2]). We investigate the ability of modern carbonate shells (Mytilus edulis) to record the δ53Cr composition of ambient seawater in order to assess their utility as a paleo-redox proxy. Samples of cultivated M. edulis from the Kiel Fjord, Germany, were analyzed for their δ53Cr composition and Cr concentrations [Cr] using TIMS. To disentangle the pathway of Cr into the carbonate shell, a series of step-digestions of their organic outer sheaths (periostraca) and their intra-layer composition were performed. Bulk analyses of specimens with intact periostraca returned 16 to 34 ppb Cr with δ53Cr values ranging from 0.28 to 0.65 ± 0.1 (2SE) and thus fall within the range of surface seawater from the Baltic Sea (0.3 - 0.6 \\permil [3]). Partial removal of periostraca resulted in lower [Cr] (5 to 17 ppb) and δ53Cr values (-0.05 ± 0.15 \\permil). These results show a positive correlation between the amount of organic matter present in a sample and both [Cr] and δ53Cr (n = 9). With nearly complete removal of periostraca, the remaining [Cr] is significantly lower (less than 5 ppb) and can only be accessed by incineration of the carbonate shell. The correlation between [Cr], δ53Cr and the amount of periostracum present in bulk samples indicates that a significant proportion of preserved Cr may be associated with the organic outer sheath. The Cr endmember accessed after incineration is less likely associated with the carbonate crystal lattice. Instead, the δ53Cr values obtained after incineration are similar to those reported from terrestrial rocks, suggesting the influence of detrital particles. Alternatively, Cr may be reduced and subsequently re-oxidized during the mineralization of biogenic carbonates [4]. Seasonal changes in primary productivity in seawater may further influence the shell

  5. Lifelong training preserves some redox-regulated adaptive responses after an acute exercise stimulus in aged human skeletal muscle.

    Science.gov (United States)

    Cobley, J N; Sakellariou, G K; Owens, D J; Murray, S; Waldron, S; Gregson, W; Fraser, W D; Burniston, J G; Iwanejko, L A; McArdle, A; Morton, J P; Jackson, M J; Close, G L

    2014-05-01

    Several redox-regulated responses to an acute exercise bout fail in aged animal skeletal muscle, including the ability to upregulate the expression of antioxidant defense enzymes and heat shock proteins (HSPs). These findings are generally derived from studies on sedentary rodent models and thus may be related to reduced physical activity and/or intraspecies differences as opposed to aging per se. This study, therefore, aimed to determine the influence of age and training status on the expression of HSPs, antioxidant enzymes, and NO synthase isoenzymes in quiescent and exercised human skeletal muscle. Muscle biopsy samples were obtained from the vastus lateralis before and 3 days after an acute high-intensity-interval exercise bout in young trained, young untrained, old trained, and old untrained subjects. Levels of HSP72, PRX5, and eNOS were significantly higher in quiescent muscle of older compared with younger subjects, irrespective of training status. 3-NT levels were elevated in muscles of the old untrained but not the old trained state, suggesting that lifelong training may reduce age-related macromolecule damage. SOD1, CAT, and HSP27 levels were not significantly different between groups. HSP27 content was upregulated in all groups studied postexercise. HSP72 content was upregulated to a greater extent in muscle of trained compared with untrained subjects postexercise, irrespective of age. In contrast to every other group, old untrained subjects failed to upregulate CAT postexercise. Aging was associated with a failure to upregulate SOD2 and a downregulation of PRX5 in muscle postexercise, irrespective of training status. In conclusion, lifelong training is unable to fully prevent the progression toward a more stressed muscular state as evidenced by increased HSP72, PRX5, and eNOS protein levels in quiescent muscle. Moreover, lifelong training preserves some (e.g., CAT) but not all (e.g., SOD2, HSP72, PRX5) of the adaptive redox-regulated responses after an

  6. Evaluación de metales redox-sensitivos como proxies de paleoxigenación en un ambiente marino hipóxico del norte de Chile Redox-sensitive metals evaluation as proxis of paleoxygenation in a hypoxic marine environment of northern Chile

    Directory of Open Access Journals (Sweden)

    JORGE VALDÉS

    2004-03-01

    principal factors to explain the metal concentrations preserved in Mejillones sediments during non-El Niño condition. When El Niño is present in the bay, the water column turn oxic, and the precipitation of redox-sensitive metals drops; so the concentration of metals decrease in the sediments. Thus, differences in concentration of metals in core top (sampled in 1996 and surface sediments (sampled in 2000 in the same area of the bay, were attributed to El Niño 1997-1998 that provoked a decrease in the flux of metals (principally nickel and cadmium toward the sediments in a more oxygenated bottom environment. All these information show that among the five metals analyzed, only nickel and cadmium seem to record paleoxygenation conditions in Mejillones. However their use as proxy is limited to the cases when extreme changes from anoxic to oxic conditions occurred in bottom sediments of this bay

  7. PGE, Re-Os, and Mo isotope systematics in Archean and early Proterozoic sedimentary systems as proxies for redox conditions of the early Earth

    Science.gov (United States)

    Siebert, C.; Kramers, J. D.; Meisel, Th.; Morel, Ph.; Nägler, Th. F.

    2005-04-01

    Re-Os data and PGE concentrations as well as Mo concentrations and isotope data are reported for suites of fine clastic sediments and black shales from the Barberton Greenstone Belt, South Africa (Fig Tree and Moodies Groups, 3.25-3.15 Ga), the Belingwe Greenstone Belt, Zimbabwe (Manjeri Formation, ca. 2.7 Ga) and shales from the Witwatersrand, Ventersdorp and Transvaal Supergroups, South Africa ranging from 2.95 to 2.2 Ga. Moderately oxidizing conditions are required to mobilize Re and Mo in the environment, Mo fractionation only occurs in solution, and these parameters thus have potential use as paleoredox proxies for the early Earth. PGE + Re abundance patterns of Barberton Greenstone Belt sediments are uniform and very similar in shape to those of komatiites. This indicates (1) that the PGE came from a source of predominantly ultramafic composition and, (2) that PGE were transported and deposited essentially in particulate form. Sediments from the younger Belingwe Greenstone Belt show more fractionated PGE + Re patterns and have Re/Os ratios 10 to 100× higher than those of Barberton sediments. Their PGE abundance patterns and Re/Os ratios are intermediate between those of the mid-Archean shales and Neoproterozoic to Recent black shales. They reflect scavenging of Re from solution in the sedimentary environment. δ 98/95Mo values of black shales of all ages correlate with their concentrations. The Barberton Greenstone Belt samples have ˜1-3 ppm Mo, similar to a granitoid-basaltic source. This Mo has δ 98/95Mo between -1.9 and -2.4‰ relative to present day mean ocean water molybdenum, MOMO and is thus not isotopically fractionated relative to such a source. Similar to the PGE this indicates transport in solid form. Sediments from the Belingwe Greenstone Belt show in part enhanced Mo concentrations (up to 6 ppm) and Mo isotope fractionation (δ 98/95Mo up to -1.4‰ relative to MOMO). The combined PGE + Re and Mo data show mainly reducing conditions in the

  8. Munchausen syndrome by proxy

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/001555.htm Munchausen syndrome by proxy To use the sharing features on this page, please enable JavaScript. Munchausen syndrome by proxy is a mental illness and ...

  9. Redox Proteomics

    OpenAIRE

    Butterfield, D. Allan; Dalle-Donne, Isabella

    2012-01-01

    Proteins are major targets of reactive oxygen and nitrogen species (ROS/RNS) and numerous post-translational, reversible or irreversible modifications have been characterized, which may lead to a change in the structure and/or function of the oxidized protein. Redox proteomics is an increasingly emerging branch of proteomics aimed at identifying and quantifying redox-based changes within the proteome both in redox signaling and under oxidative stress conditions. Correlation between protein ox...

  10. Here be web proxies

    DEFF Research Database (Denmark)

    Weaver, Nicholas; Kreibich, Christian; Dam, Martin

    2014-01-01

    HTTP proxies serve numerous roles, from performance enhancement to access control to network censorship, but often operate stealthily without explicitly indicating their presence to the communicating endpoints. In this paper we present an analysis of the evidence of proxying manifest in executions...... of the ICSI Netalyzr spanning 646,000 distinct IP addresses ("clients"). To identify proxies we employ a range of detectors at the transport and application layer, and report in detail on the extent to which they allow us to fingerprint and map proxies to their likely intended uses. We also analyze 17...

  11. Jemen - the Proxy War

    Directory of Open Access Journals (Sweden)

    Magdalena El Ghamari

    2015-12-01

    Full Text Available The military operation in Yemen is significant departure from Saudi Arabia's foreign policy tradition and customs. Riyadh has always relied on three strategies to pursue its interests abroad: wealth, establish a global network and muslim education and diplomacy and meadiation. The term "proxy war" has experienced a new popularity in stories on the Middle East. A proxy war is two opposing countries avoiding direct war, and instead supporting combatants that serve their interests. In some occasions, one country is a direct combatant whilst the other supporting its enemy. Various news sources began using the term to describe the conflict in Yemen immediately, as if on cue, after Saudi Arabia launched its bombing campaign against Houthi targets in Yemen on 25 March 2015. This is the reason, why author try to answer for following questions: Is the Yemen Conflict Devolves into Proxy War? and Who's fighting whom in Yemen's proxy war?" Research area includes the problem of proxy war in the Middle East. For sure, the real problem of proxy war must begin with the fact that the United States and its NATO allies opened the floodgates for regional proxy wars by the two major wars for regime change: in Iraq and Libya. Those two destabilising wars provided opportunities and motives for Sunni states across the Middle East to pursue their own sectarian and political power objectives through "proxy war".

  12. Redox proteomics.

    Science.gov (United States)

    Butterfield, D Allan; Dalle-Donne, Isabella

    2012-12-01

    Proteins are major targets of reactive oxygen and nitrogen species (ROS/RNS) and numerous post-translational, reversible or irreversible modifications have been characterized, which may lead to a change in the structure and/or function of the oxidized protein. Redox proteomics is an increasingly emerging branch of proteomics aimed at identifying and quantifying redox-based changes within the proteome both in redox signaling and under oxidative stress conditions. Correlation between protein oxidation and human disease is widely accepted, although elucidating cause and effect remains a challenge. Increasing biomedical data have provided compelling evidences for the involvement of perturbations in redox homeostasis in a large number of pathophysiological conditions and aging. Research toward a better understanding of the molecular mechanisms of a disease together with identification of specific targets of oxidative damage is urgently required. This is the power and potential of redox proteomics. In the last few years, combined proteomics, mass spectrometry (MS), and affinity chemistry-based methodologies have contributed in a significant way to provide a better understanding of protein oxidative modifications occurring in various biological specimens under different physiological and pathological conditions. Hence, this Forum on Redox Proteomics is timely. Original and review articles are presented on various subjects ranging from redox proteomics studies of oxidatively modified brain proteins in Alzheimer disease and animal models of Alzheimer and Parkinson disease, to potential new biomarker discovery paradigm for human disease, to chronic kidney disease, to protein nitration in aging and age-related neurodegenerative disorders, electrophile-responsive proteomes of special relevance to diseases involving mitochondrial alterations, to cardiovascular physiology and pathology.

  13. Jemen - the Proxy War

    OpenAIRE

    Magdalena El Ghamari

    2015-01-01

    The military operation in Yemen is significant departure from Saudi Arabia's foreign policy tradition and customs. Riyadh has always relied on three strategies to pursue its interests abroad: wealth, establish a global network and muslim education and diplomacy and meadiation. The term "proxy war" has experienced a new popularity in stories on the Middle East. A proxy war is two opposing countries avoiding direct war, and instead supporting combatants that serve their interests. In some occas...

  14. Molecular proxies for paleoclimatology

    Science.gov (United States)

    Eglinton, Timothy I.; Eglinton, Geoffrey

    2008-10-01

    We summarize the applications of molecular proxies in paleoclimatology. Marine molecular records especially are proving to be of value but certain environmentally persistent compounds can also be measured in lake sediments, loess deposits and ice cores. The fundamentals of this approach are the molecular parameters, the compound abundances and carbon, hydrogen, nitrogen and oxygen isotopic contents which can be derived by the analysis of sediment extracts. These afford proxy measures which can be interpreted in terms of the conditions which control climate and also reflect its operation. We discuss two types of proxy; those of terrigenous and those of aquatic origin, and exemplify their application in the study of marine sediments through the medium of ten case studies based in the Atlantic, Mediterranean and Pacific Oceans, and in Antarctica. The studies are mainly for periods in the present, the Holocene and particularly the last glacial/interglacial, but they also include one study from the Cretaceous. The terrigenous proxies, which are measures of continental vegetation, are based on higher plant leaf wax compounds, i.e. long-chain (circa C 30) hydrocarbons, alcohols and acids. They register the relative contributions of C 3 vs. C 4 type plants to the vegetation in the source areas. The two marine proxies are measures of sea surface temperatures (SST). The longer established one, (U 37K') is based on the relative abundances of C 37 alkenones photosynthesized by unicellular algae, members of the Haptophyta. The newest proxy (TEX 86) is based on C 86 glycerol tetraethers (GDGTs) synthesized in the water column by some of the archaeal microbiota, the Crenarchaeota.

  15. Apatite: a new redox proxy for silicic magmas?

    OpenAIRE

    Miles, A.J.; Graham, C M; Hawkesworth, C.J.; Gillespie, M.R.; Hinton, R.W.; Bromiley, G.D.

    2014-01-01

    The oxidation states of magmas provide valuable information about the release and speciation of volatile elements during volcanic eruptions, metallogenesis, source rock compositions, open system magmatic processes, tectonic settings and potentially titanium (Ti) activity in chemical systems used for Ti-dependent geothermometers and geobarometers. In this paper we explore the use of Mn in apatite as an oxybarometer in intermediate and silicic igneous rocks. Increased Mn concentrations in apati...

  16. Stimulus Responsive Nanoparticles

    Science.gov (United States)

    Cairns, Darran Robert (Inventor); Huebsch, Wade W. (Inventor); Sierros, Konstantinos A. (Inventor); Shafran, Matthew S. (Inventor)

    2017-01-01

    Disclosed are various embodiments of methods and systems related to stimulus responsive nanoparticles. In one embodiment including a stimulus responsive nanoparticle system, the system includes a first electrode, a second electrode, and a plurality of elongated electro-responsive nanoparticles dispersed between the first and second electrodes, the plurality of electro-responsive nanorods configured to respond to an electric field established between the first and second electrodes.

  17. Proxy Smart Card Systems

    OpenAIRE

    Cattaneo, Giuseppe; Faruolo, Pompeo; Palazzo, Vincenzo; Visconti, Ivan

    2010-01-01

    International audience; The established legal value of digital signatures and the growing availability of identity-based digital services are progressively extending the use of smart cards to all citizens, opening new challenging scenarios. Among them, motivated by concrete applications, secure and practical delegation of digital signatures is becoming more and more critical. Unfortunately, secure delegation systems proposed so far (e.g., proxy signatures) include various drawbacks for any pr...

  18. Munchausen syndrome by proxy

    Directory of Open Access Journals (Sweden)

    Jovanović Aleksandar A.

    2005-01-01

    Full Text Available This review deals with bibliography on Munchausen syndrome by proxy (MSbP. The name of this disorder was introduced by English psychiatrist Roy Meadow who pointed to diagnostic difficulties as well as to serious medical and legal connotations of MSbP. MSbP was classified in DSM-IV among criteria sets provided for further study as "factitious disorder by proxy", while in ICD-10, though not explicitly cited, MSbP might be classified as "factitious disorders" F68.1. MSbP is a special form of abuse where the perpetrator induces somatic or mental symptoms of illness in the victim under his/her care and then persistently presents the victims for medical examinations and care. The victim is usually a preschool child and the perpetrator is the child's mother. Motivation for such pathological behavior of perpetrator is considered to be unconscious need to assume sick role by proxy while external incentives such as economic gain are absent. Conceptualization of MSbP development is still in the domain of psychodynamic speculation, its course is chronic and the prognosis is poor considering lack of consistent, efficient and specific treatment. The authors also present the case report of thirty-three year-old mother who had been abusing her nine year-old son both emotionally and physically over the last several years forcing him to, together with her, report to the police, medical and educational institutions that he had been the victim of rape, poisoning and beating by various individuals, especially teaching and medical staff. Mother manifested psychosis and her child presented with impaired cognitive development, emotional problems and conduct disorder.

  19. [Munchausen by proxy syndrome].

    Science.gov (United States)

    Depauw, A; Loas, G; Delhaye, M

    2015-01-01

    The Munchausen syndrome by proxy (MSBP) was first described in 1977 by the English paediatrician Roy Meadow. The MSBP is an extremely complicated diagnosis because of the difficulty in finding the incriminating evidence of its existence and because of the ethical issue it raises for caregivers. Its implications from a medical, psychological and legal point of view raise difficult questions for any professional confronted to it. In this article we will first present the case of a 16-year-old teenager who had been bedridden in hospital for a year, before an atypical form of MSBP was finally diagnosed, after a stay in a child and adolescent psychiatry unit. We will then discuss this case in light of a literature review on the MSBP.

  20. Stimulus Variables and Interpersonal Attraction: The Stimulus Context.

    Science.gov (United States)

    Griffitt, William

    In interpersonal attraction, studies and judgment research evaluation of a stimulus is often a function of the context within which the stimulus appears. The first experiment was designed to examine "contrast effects" (shifts in the rated value of a stimulus away from the contextual values) when all attitudinal information was received from two…

  1. Proxy consent: moral authority misconceived.

    Science.gov (United States)

    Wrigley, A

    2007-09-01

    The Mental Capacity Act 2005 has provided unified scope in the British medical system for proxy consent with regard to medical decisions, in the form of a lasting power of attorney. While the intentions are to increase the autonomous decision making powers of those unable to consent, the author of this paper argues that the whole notion of proxy consent collapses into a paternalistic judgement regarding the other person's best interests and that the new legislation introduces only an advisor, not a proxy with the moral authority to make treatment decisions on behalf of another. The criticism is threefold. First, there is good empirical evidence that people are poor proxy decision makers as regards accurately representing other people's desires and wishes, and this is therefore a pragmatically inadequate method of gaining consent. Second, philosophical theory explaining how we represent other people's thought processes indicates that we are unlikely ever to achieve accurate simulations of others' wishes in making a proxy decision. Third, even if we could accurately simulate other people's beliefs and wishes, the current construction of proxy consent in the Mental Capacity Act means that it has no significant ethical authority to match that of autonomous decision making. Instead, it is governed by a professional, paternalistic, best-interests judgement that undermines the intended role of a proxy decision maker. The author argues in favour of clearly adopting the paternalistic best-interests option and viewing the proxy as solely an advisor to the professional medical team in helping make best-interests judgements.

  2. Private Computing with Untrustworthy Proxies

    NARCIS (Netherlands)

    Gedrojc, B.

    2011-01-01

    The objective of this thesis is to preserve privacy for the user while untrustworthy proxies are involved in the communication and computation i.e. private computing. A basic example of private computing is an access control system (proxy) which grants access (or not) to users based on fingerprints.

  3. A Parallel Distributed Processing Model of Stimulus-Stimulus and Stimulus-Response Compatibility.

    Science.gov (United States)

    Huazhong, Harry Zhang; Zhang, Jun; Kornblum, Sylvan

    1999-01-01

    Proposes a parallel distributed-processing (PDP) model to account for choice-reaction-time performance in diverse cognitive and perceptual tasks that are interrelated in terms of stimulus-stimulus and stimulus-response overlap. Simulation results support the PDP model. (SLD)

  4. Robotic Vehicle Proxy Simulation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Energid Technologies proposes the development of a digital simulation that can replace robotic vehicles in field studies. This proxy simulation will model the...

  5. Plant redox proteomics

    DEFF Research Database (Denmark)

    Navrot, Nicolas; Finnie, Christine; Svensson, Birte

    2011-01-01

    In common with other aerobic organisms, plants are exposed to reactive oxygen species resulting in formation of post-translational modifications related to protein oxidoreduction (redox PTMs) that may inflict oxidative protein damage. Accumulating evidence also underscores the importance of redox...... PTMs in regulating enzymatic activities and controlling biological processes in plants. Notably, proteins controlling the cellular redox state, e.g. thioredoxin and glutaredoxin, appear to play dual roles to maintain oxidative stress resistance and regulate signal transduction pathways via redox PTMs....... To get a comprehensive overview of these types of redox-regulated pathways there is therefore an emerging interest to monitor changes in redox PTMs on a proteome scale. Compared to some other PTMs, e.g. protein phosphorylation, redox PTMs have received less attention in plant proteome analysis, possibly...

  6. Neural Correlates of Stimulus Reportability

    OpenAIRE

    Hulme, Oliver J.; Friston, Karl F.; Zeki, Semir

    2009-01-01

    Most experiments on the “neural correlates of consciousness” employ stimulus reportability as an operational definition of what is consciously perceived. The interpretation of such experiments therefore depends critically on understanding the neural basis of stimulus reportability. Using a high volume of fMRI data, we investigated the neural correlates of stimulus reportability using a partial report object detection paradigm. Subjects were presented with a random array of circularly arranged...

  7. Neural correlates of stimulus reportability.

    Science.gov (United States)

    Hulme, Oliver J; Friston, Karl F; Zeki, Semir

    2009-08-01

    Most experiments on the "neural correlates of consciousness" employ stimulus reportability as an operational definition of what is consciously perceived. The interpretation of such experiments therefore depends critically on understanding the neural basis of stimulus reportability. Using a high volume of fMRI data, we investigated the neural correlates of stimulus reportability using a partial report object detection paradigm. Subjects were presented with a random array of circularly arranged disc-stimuli and were cued, after variable delays (following stimulus offset), to report the presence or absence of a disc at the cued location, using variable motor actions. By uncoupling stimulus processing, decision, and motor response, we were able to use signal detection theory to deconstruct the neural basis of stimulus reportability. We show that retinotopically specific responses in the early visual cortex correlate with stimulus processing but not decision or report; a network of parietal/temporal regions correlates with decisions but not stimulus presence, whereas classical motor regions correlate with report. These findings provide a basic framework for understanding the neural basis of stimulus reportability without the theoretical burden of presupposing a relationship between reportability and consciousness.

  8. Qualitative and Quantitative Sentiment Proxies

    DEFF Research Database (Denmark)

    Zhao, Zeyan; Ahmad, Khurshid

    2015-01-01

    Sentiment analysis is a content-analytic investigative framework for researchers, traders and the general public involved in financial markets. This analysis is based on carefully sourced and elaborately constructed proxies for market sentiment and has emerged as a basis for analysing movements...... and trading volumes. The case study we use is a small market index (Danish Stock Exchange Index, OMXC 20, together with prevailing sentiment in Denmark, to evaluate the impact of sentiment on OMXC 20. Furthermore, we introduce a rather novel and quantitative sentiment proxy, that is the use of the index...

  9. Munchausen syndrome by proxy: a case report.

    Science.gov (United States)

    Lieder, Holly S; Irving, Sharon Y; Mauricio, Rizalina; Graf, Jeanine M

    2005-01-01

    Munchausen syndrome by proxy is difficult to diagnose unless healthcare providers are astute to its clinical features and management. A case is presented to educate nurses and advanced practice nurses, of the nursing, medical, legal, and social complexities associated with Munchausen syndrome by proxy. This article also provides a brief review of the definition of Munchausen syndrome by proxy, its epidemiology, common features of the perpetrator, implications for healthcare personnel, and the legal and international ramifications of Munchausen syndrome by proxy.

  10. Shareholder Activism Through the Proxy Process

    NARCIS (Netherlands)

    Renneboog, L.D.R.; Szilagyi, P.G.

    2009-01-01

    This paper provides evidence on the corporate governance role of shareholder-initiated proxy proposals. Previous studies debate over whether activists use proxy proposals to discipline firms or to simply advance their self-serving agendas, and whether proxy proposals are effective at all in

  11. Shareholder Activism through the Proxy Process

    NARCIS (Netherlands)

    Renneboog, L.D.R.; Szilagyi, P.G.

    2009-01-01

    This paper provides evidence on the corporate governance role of shareholderinitiated proxy proposals. Previous studies debate over whether activists use proxy proposals to discipline firms or to simply advance their self-serving agendas, and whether proxy proposals are effective at all in

  12. Redox Species of Redox Flow Batteries: A Review

    Directory of Open Access Journals (Sweden)

    Feng Pan

    2015-11-01

    Full Text Available Due to the capricious nature of renewable energy resources, such as wind and solar, large-scale energy storage devices are increasingly required to make the best use of the renewable power. The redox flow battery is considered suitable for large-scale applications due to its modular design, good scalability and flexible operation. The biggest challenge of the redox flow battery is the low energy density. The redox active species is the most important component in redox flow batteries, and the redox potential and solubility of redox species dictate the system energy density. This review is focused on the recent development of redox species. Different categories of redox species, including simple inorganic ions, metal complexes, metal-free organic compounds, polysulfide/sulfur and lithium storage active materials, are reviewed. The future development of redox species towards higher energy density is also suggested.

  13. Measuring SIP proxy server performance

    CERN Document Server

    Subramanian, Sureshkumar V

    2013-01-01

    Internet Protocol (IP) telephony is an alternative to the traditional Public Switched Telephone Networks (PSTN), and the Session Initiation Protocol (SIP) is quickly becoming a popular signaling protocol for VoIP-based applications. SIP is a peer-to-peer multimedia signaling protocol standardized by the Internet Engineering Task Force (IETF), and it plays a vital role in providing IP telephony services through its use of the SIP Proxy Server (SPS), a software application that provides call routing services by parsing and forwarding all the incoming SIP packets in an IP telephony network.SIP Pr

  14. Novel Quantum Proxy Signature without Entanglement

    Science.gov (United States)

    Xu, Guang-bao

    2015-08-01

    Proxy signature is an important research topic in classic cryptography since it has many application occasions in our real life. But only a few quantum proxy signature schemes have been proposed up to now. In this paper, we propose a quantum proxy signature scheme, which is designed based on quantum one-time pad. Our scheme can be realized easily since it only uses single-particle states. Security analysis shows that it is secure and meets all the properties of a proxy signature, such as verifiability, distinguishability, unforgeability and undeniability.

  15. Genetically Encoded Fluorescent Redox Probes

    OpenAIRE

    Hui-Wang Ai; Wei Ren

    2013-01-01

    Redox processes are involved in almost every cell of the body as a consequence of aerobic life. In the past decades, redox biology has been increasingly recognized as one of the key themes in cell signaling. The progress has been accelerated by development of fluorescent probes that can monitor redox conditions and dynamics in cells and cell compartments. This short paper focuses on fluorescent redox probes that are genetically encoded, and discusses their properties, molecular mechanism, adv...

  16. Redox Flow Batteries, a Review

    Energy Technology Data Exchange (ETDEWEB)

    Knoxville, U. Tennessee; U. Texas Austin; U, McGill; Weber, Adam Z.; Mench, Matthew M.; Meyers, Jeremy P.; Ross, Philip N.; Gostick, Jeffrey T.; Liu, Qinghua

    2011-07-15

    Redox flow batteries are enjoying a renaissance due to their ability to store large amounts of electrical energy relatively cheaply and efficiently. In this review, we examine the components of redox flow batteries with a focus on understanding the underlying physical processes. The various transport and kinetic phenomena are discussed along with the most common redox couples.

  17. Redox Flow Batteries, a Review

    OpenAIRE

    Weber, Adam Z.

    2013-01-01

    Redox flow batteries are enjoying a renaissance due to their ability to store large amounts of electrical energy relatively cheaply and efficiently. In this review, we examine the components of redox flow batteries with a focus on understanding the underlying physical processes. The various transport and kinetic phenomena are discussed along with the most common redox couples.

  18. Genetically Encoded Fluorescent Redox Probes

    Directory of Open Access Journals (Sweden)

    Hui-Wang Ai

    2013-11-01

    Full Text Available Redox processes are involved in almost every cell of the body as a consequence of aerobic life. In the past decades, redox biology has been increasingly recognized as one of the key themes in cell signaling. The progress has been accelerated by development of fluorescent probes that can monitor redox conditions and dynamics in cells and cell compartments. This short paper focuses on fluorescent redox probes that are genetically encoded, and discusses their properties, molecular mechanism, advantages and pitfalls. Our recent work on reaction-based encoded probes that are responsive to particular redox signaling molecules is also reviewed. Future challenges and directions are also commented.

  19. Genetically encoded fluorescent redox probes.

    Science.gov (United States)

    Ren, Wei; Ai, Hui-Wang

    2013-11-11

    Redox processes are involved in almost every cell of the body as a consequence of aerobic life. In the past decades, redox biology has been increasingly recognized as one of the key themes in cell signaling. The progress has been accelerated by development of fluorescent probes that can monitor redox conditions and dynamics in cells and cell compartments. This short paper focuses on fluorescent redox probes that are genetically encoded, and discusses their properties, molecular mechanism, advantages and pitfalls. Our recent work on reaction-based encoded probes that are responsive to particular redox signaling molecules is also reviewed. Future challenges and directions are also commented.

  20. Temporal and spectral profiles of stimulus-stimulus and stimulus-response conflict processing.

    Science.gov (United States)

    Wang, Kai; Li, Qi; Zheng, Ya; Wang, Hongbin; Liu, Xun

    2014-04-01

    The ability to detect and resolve conflict is an essential function of cognitive control. Laboratory studies often use stimulus-response-compatibility (SRC) tasks to examine conflict processing in order to elucidate the mechanism and modular organization of cognitive control. Inspired by two influential theories regarding cognitive control, the conflict monitoring theory (Botvinick, Braver, Barch, Carter, & Cohen, 2001) and dimensional overlap taxonomy (Kornblum, Hasbroucq, & Osman, 1990), we explored the temporal and spectral similarities and differences between processing of stimulus-stimulus (S-S) and stimulus-response (S-R) conflicts with event related potential (ERP) and time-frequency measures. We predicted that processing of S-S conflict starts earlier than that of S-R conflict and that the two types of conflict may involve different frequency bands. Participants were asked to perform two parallel SRC tasks, both combining the Stroop task (involving S-S conflict) and Simon task (involving S-R conflict). ERP results showed pronounced SRC effects (incongruent vs. congruent) on N2 and P3 components for both S-S and S-R conflicts. In both tasks, SRC effects of S-S conflict took place earlier than those of S-R conflict. Time-frequency analysis revealed that both types of SRC effects modulated theta and alpha bands, while S-R conflict effects additionally modulated power in the beta band. These results indicated that although S-S and S-R conflict processing shared considerable ERP and time-frequency properties, they differed in temporal and spectral dynamics. We suggest that the modular organization of cognitive control should take both commonality and distinction of S-S and S-R conflict processing into consideration. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. Munchausen Syndrome by Proxy: Identification and Intervention

    Science.gov (United States)

    Walk, Alexandra; Davies, Susan C.

    2010-01-01

    This article discusses the Munchausen syndrome by proxy (MSBP), also known as "factitious disorder by proxy" (FDBP) and fabricated and/or induced illness, which is a mental illness in which a person lies about the physical or mental well-being of a person he/she is responsible for. Most often the dynamic transpires between a mother and her child.…

  2. Ediacaran Redox Fluctuations

    Science.gov (United States)

    Sahoo, S. K.; Jiang, G.; Planavsky, N. J.; Kendall, B.; Owens, J. D.; Anbar, A. D.; Lyons, T. W.

    2013-12-01

    Evidence for pervasive oxic conditions, and likely even deep ocean oxygenation has been documented at three intervals in the lower (ca. 632 Ma), middle (ca. 580 Ma) and upper (ca. 551 Ma) Ediacaran. The Doushantuo Formation in South China hosts large enrichments of redox-sensitive trace element (e.g., molybdenum, vanadium and uranium) in anoxic shales, which are indicative of a globally oxic ocean-atmosphere system. However, ocean redox conditions between these periods continue to be a topic of debate and remain elusive. We have found evidence for widespread anoxic conditions through much of the Ediacaran in the deep-water Wuhe section in South China. During most of the Ediacaran-early Cambrian in basinal sections is characterized by Fe speciation data and pyrite morphologies that indicate deposition under euxinic conditions with near-crustal enrichments of redox-sensitive element and positive pyrite-sulfur isotope values, which suggest low levels of marine sulfate and widespread euxinia. Our work reinforces an emerging view that the early Earth, including the Ediacaran, underwent numerous rises and falls in surface oxidation state, rather than a unidirectional rise as originally imagined. The Ediacaran ocean thus experienced repetitive expansion and contraction of marine chalcophilic trace-metal levels that may have had fundamental impact on the slow evolution of early animals and ecosystems. Further, this framework forces us to re-examine the relationship between Neoproterozoic oxygenation and metazoan diversification. Varying redox conditions through the Cryogenian and Ediacaran may help explain molecular clock and biomarker evidence for an early appearance and initial diversification of metazoans but with a delay in the appearance of most major metazoan crown groups until close to Ediacaran-Cambrian boundary.

  3. Hot semiworks Redox studies

    Energy Technology Data Exchange (ETDEWEB)

    Evans, T.F.; Tomlinson, R.E.

    1954-01-27

    The separations Hot Semiworks at the Hanford Atomic Products Operation was built in order to: (1) develop optimum conditions for the economic operation of the Redox and TBP plants, (2) procure engineering design data which would allow the specification of process equipment required for new processes such as Purex, (3) provide facilities for the study of future process and engineering problems on a semiworks scale employing radioactive process solutions, and (4) provide facilities for immediate trouble shooting for urgent separations plant problems. The initial operation of this facility was designed to develop conditions for the economic operation of the Redox Plant. These studies, covering a period from November, 1952 to October, 1953, are described in this report. The Redox process is used at Hanford for the separation of uranium and plutonium from fission products and from each other. The basis of the process is the preferential extraction of uranium and plutonium nitrates from an aqueous phase of high salting strength into an organic solvent (methyl isobutyl ketone) to effect the separation from fission products. This operation is conducted continuously in columns, packed with Raschig rings, through which the phases are passed counter-currently. Uranium and plutonium are separated by converting the plutonium to a lower valence state, in which form it is preferentially extracted back into an aqueous phase of high salting strength in a second column. Uranium is then returned to an aqueous phase of low salting strength in a third column. The products are further decontaminated in similar additional cycles. A detailed description of the process is given in the Redox Technical Manual.

  4. Trace element profiles in sediments as proxies of dead zone history; rhenium compared to molybdenum.

    Science.gov (United States)

    Helz, George R; Adelson, Jordan M

    2013-02-05

    Warm-season dead zones-volumes of coastal water containing too little O(2) to support macrofauna-are a growing global menace. Trace elements that are deposited in sediments in response to reducing or sulfidic conditions can provide proxy records for reconstructing dead zone evolution. Based on relative enrichment in reduced vs oxidized marine sediments, Re seems promising as a dead zone proxy. Here, Re is determined by isotope dilution mass spectrometry in sediments underlying the summertime dead zone in Chesapeake Bay. Contrary to expectation, Re becomes only modestly (∼2-fold) elevated during the 20th century and fails to track the historic record of summertime O(2) depletion. Rhenium enrichments are watershed-specific and apparently controlled by anthropogenic sources, not by redox-linked authigenic processes. In contrast, Mo enrichments do track historic O(2) depletion. Three factors cause redox control to override anthropogenic control in the case of Mo: relative to weathering fluxes, anthropogenic Mo fluxes are weaker than Re fluxes; during anoxic periods, Mn refluxing amplifies Mo but not Re concentrations near the sediment surface; and high pore water sulfide-polysulfide promotes Mo fixation in pyrite while promoting formation of organo-Re adducts; the latter are too mobile and reactive to preserve a reliable historic record under seasonally fluctuating redox conditions.

  5. Stimulus conflict triggers behavioral avoidance.

    Science.gov (United States)

    Dignath, David; Eder, Andreas B

    2015-12-01

    According to a recent extension of the conflict-monitoring theory, conflict between two competing response tendencies is registered as an aversive event and triggers a motivation to avoid the source of conflict. In the present study, we tested this assumption. Over five experiments, we examined whether conflict is associated with an avoidance motivation and whether stimulus conflict or response conflict triggers an avoidance tendency. Participants first performed a color Stroop task. In a subsequent motivation test, participants responded to Stroop stimuli with approach- and avoidance-related lever movements. These results showed that Stroop-conflict stimuli increased the frequency of avoidance responses in a free-choice motivation test, and also increased the speed of avoidance relative to approach responses in a forced-choice test. High and low proportions of response conflict in the Stroop task had no effect on avoidance in the motivation test. Avoidance of conflict was, however, obtained even with new conflict stimuli that had not been presented before in a Stroop task, and when the Stroop task was replaced with an unrelated filler task. Taken together, these results suggest that stimulus conflict is sufficient to trigger avoidance.

  6. Stimulus ambiguity elicits response conflict.

    Science.gov (United States)

    Szmalec, Arnaud; Verbruggen, Frederick; Vandierendonck, André; De Baene, Wouter; Verguts, Tom; Notebaert, Wim

    2008-04-18

    Conflict monitoring theory [M.M. Botvinick, T. Braver, D. Barch, C. Carter, J.D. Cohen, Conflict monitoring and cognitive control, Psychol. Rev. 108 (2001) 625-652] assumes that perceptual ambiguity among choice stimuli elicits response conflict in choice reaction. It hence predicts that response conflict is also involved in elementary variants of choice reaction time (RT) tasks, i.e., those variants that, by contrast with the Stroop task or the Go/No-Go task for instance, are rarely associated with cognitive control. In order to test this prediction, an experiment was designed in which participants performed a simple RT task and a regular between-hand 2-choice RT task under three different levels of stimulus ambiguity. The data show that response conflict, as measured by the N2 component of the event-related brain potential (ERP), was elicited in the 2-choice RT task but not in the simple RT task and that the degree of response conflict in the 2-choice RT task was a function of stimulus ambiguity. These results show that response conflict is also present in a regular choice RT task which is traditionally not considered to be a measure of cognitive conflict.

  7. Carving Executive Control At Its Joints: Working Memory Capacity Predicts Stimulus-Stimulus, But Not Stimulus-Response, Conflict

    OpenAIRE

    Meier, Matt E.; Kane, Michael J.

    2015-01-01

    Three experiments examined the relation between working memory capacity (WMC) and two different forms of cognitive conflict: stimulus-stimulus (S-S) and stimulus-response (SR) interference. Our goal was to test whether WMC’s relation to conflict-task performance is mediated by stimulus-identification processes (captured by S-S conflict), response-selection processes (captured by S-R conflict), or both. In Experiment 1, subjects completed a single task presenting both S-S and S-R conflict tria...

  8. The Redox Chemistry of Rainwater

    Science.gov (United States)

    Willey, J. D.; Mullaugh, K. M.; Kieber, R. J.; Avery, B.; Mead, R. N.

    2011-12-01

    Oxidation-reduction processes affect the chemical speciation of many inorganic and organic species in rainwater. The presence and concentrations of certain reactive radicals is also critically dependent upon redox chemistry. There are many oxidants and reductants in rainwater, and hence many competing redox reactions. Measurement of both halves of a redox couple can yield important information about rainwater pe- (-log electron activity) and also identify relevant oxidants and reductants for that particular redox speciation. Several redox couples have been measured in rainwater in Wilmington, NC, USA, as well as at other locations. There are at least three relevant oxidant-reductant couples in rainwater rather than a unique pe-. Mn redox speciation responds to the molecular oxygen-water couple (pe- = 15.9 for rainwater in contact with air and pH of 4.7). Fe, Hg and the nitrate-nitrite-ammonium system appear to be controlled by the molecular oxygen-hydrogen peroxide couple, with hydrogen peroxide acting as a reductant (pe- = 9.2). Cu responds to superoxide as a reductant with molecular oxygen as an oxidant (pe- = 2.7). Direct Pt electrode measurements of redox potential in rainwater consistently yield lower redox potentials than predicted by the molecular oxygen-water couple, indicating the redox chemistry of rainwater is more complex and rainwater is less oxidizing than previously thought.

  9. New proxy replacement algorithm for multimedia streaming

    Science.gov (United States)

    Wong, Hau Ling; Lo, Kwok-Tung

    2001-11-01

    Proxy servers play an important role in between servers and clients in various multimedia systems on the Internet. Since proxy servers do not have an infinite-capacity cache for keeping all the continuous media data, the challenge for the replacement policy is to determine which streams should be cached or removed from the proxy server. In this paper, a new proxy replacement algorithm, named the Least Popular Used (LPU) caching algorithm, is proposed for layered encoded multimedia streams in the Internet. The LPU method takes both the short-term and long-term popularity of the video into account in determining the replacement policy. Simulation evaluation shows that our proposed scheme achieves better results than some existing methods in term of the cache efficiency and replacement frequency under both static and dynamic access environments.

  10. 78 FR 70987 - Proxy Advisory Firm Roundtable

    Science.gov (United States)

    2013-11-27

    ... of proxy advisory firm use by investment advisers and institutional investors and potential changes... Special Counsel, Division of Investment Management, at 202-551-6700, or Raymond Be, Special Counsel...

  11. A serial Munchausen syndrome by proxy

    National Research Council Canada - National Science Library

    Esra Unal; Volkan Unal; Ali Gul; Mustafa Celtek; Behzat Diken; Ibrahim Balcioglu

    2017-01-01

    Munchausen syndrome by proxy (MSBP) is a form of child abuse that describes children whose parents or caregivers invent illness stories and substantiate the stories by fabricating false physical signs...

  12. Seizures and Munchausen Syndrome by Proxy

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2002-05-01

    Full Text Available The prevalence, morbidity and mortality, diagnosis and management of cases of fabricated seizures and child abuse (Munchausen syndrome by proxy (MSbp are assessed by pediatricians at the University of Wales College of Medicine, Cardiff, UK.

  13. Munchausen Syndrome by Proxy: A Clinical Vignette

    Science.gov (United States)

    Zylstra, Robert G.; Miller, Karl E.; Stephens, Walter E.

    2000-01-01

    Munchausen syndrome by proxy is the act of one person fabricating or inducing an illness in another to meet his or her own emotional needs through the treatment process. The diagnosis is poorly understood and controversial. We report here the case of a 6-year-old boy who presented with possible pneumonia, nausea, vomiting, and diarrhea and whose mother was suspected of Munchausen syndrome by proxy. PMID:15014581

  14. PENGELOLAAN JARINGAN INTERNET DENGAN PROXY WINGATE

    Directory of Open Access Journals (Sweden)

    Titin Winarti

    2005-01-01

    Full Text Available Proxy adalah bagian dari protokol yang berfungsi sebagai link untuk host tunggal atau sebagai link untuk beberapa host antarajaringan dan jaringan lain. Proxy wingate adalah software yang digunakan untuk berbagi koneksi internet melalui satu alamat IPyang terintegrasi ke internet.

  15. Web proxy auto discovery for the WLCG

    CERN Document Server

    Dykstra, D; Blumenfeld, B; De Salvo, A; Dewhurst, A; Verguilov, V

    2017-01-01

    All four of the LHC experiments depend on web proxies (that is, squids) at each grid site to support software distribution by the CernVM FileSystem (CVMFS). CMS and ATLAS also use web proxies for conditions data distributed through the Frontier Distributed Database caching system. ATLAS & CMS each have their own methods for their grid jobs to find out which web proxies to use for Frontier at each site, and CVMFS has a third method. Those diverse methods limit usability and flexibility, particularly for opportunistic use cases, where an experiment’s jobs are run at sites that do not primarily support that experiment. This paper describes a new Worldwide LHC Computing Grid (WLCG) system for discovering the addresses of web proxies. The system is based on an internet standard called Web Proxy Auto Discovery (WPAD). WPAD is in turn based on another standard called Proxy Auto Configuration (PAC). Both the Frontier and CVMFS clients support this standard. The input into the WLCG system comes from squids regis...

  16. Direct electrochemistry of redox proteins

    NARCIS (Netherlands)

    Heering, H.A.

    1995-01-01

    The goal of the project was to obtain more detailed insight in interactions between redox proteins and solid electrodes and the mechanisms of electron transfer. In addition to this, the influence of the protein environment on the redox properties of the active site and the possible

  17. Inferring climate variability from skewed proxy records

    Science.gov (United States)

    Emile-Geay, J.; Tingley, M.

    2013-12-01

    Many paleoclimate analyses assume a linear relationship between the proxy and the target climate variable, and that both the climate quantity and the errors follow normal distributions. An ever-increasing number of proxy records, however, are better modeled using distributions that are heavy-tailed, skewed, or otherwise non-normal, on account of the proxies reflecting non-normally distributed climate variables, or having non-linear relationships with a normally distributed climate variable. The analysis of such proxies requires a different set of tools, and this work serves as a cautionary tale on the danger of making conclusions about the underlying climate from applications of classic statistical procedures to heavily skewed proxy records. Inspired by runoff proxies, we consider an idealized proxy characterized by a nonlinear, thresholded relationship with climate, and describe three approaches to using such a record to infer past climate: (i) applying standard methods commonly used in the paleoclimate literature, without considering the non-linearities inherent to the proxy record; (ii) applying a power transform prior to using these standard methods; (iii) constructing a Bayesian model to invert the mechanistic relationship between the climate and the proxy. We find that neglecting the skewness in the proxy leads to erroneous conclusions and often exaggerates changes in climate variability between different time intervals. In contrast, an explicit treatment of the skewness, using either power transforms or a Bayesian inversion of the mechanistic model for the proxy, yields significantly better estimates of past climate variations. We apply these insights in two paleoclimate settings: (1) a classical sedimentary record from Laguna Pallcacocha, Ecuador (Moy et al., 2002). Our results agree with the qualitative aspects of previous analyses of this record, but quantitative departures are evident and hold implications for how such records are interpreted, and

  18. Genetically encoded fluorescent redox sensors.

    Science.gov (United States)

    Lukyanov, Konstantin A; Belousov, Vsevolod V

    2014-02-01

    Life is a constant flow of electrons via redox couples. Redox reactions determine many if not all major cellular functions. Until recently, redox processes remained hidden from direct observation in living systems due to the lack of adequate methodology. Over the last years, imaging tools including small molecule probes and genetically encoded sensors appeared, which provided, for the first time, an opportunity to visualize and, in some cases, quantify redox reactions in live cells. Genetically encoded fluorescent redox probes, such as HyPer, rxYFP and roGFPs, have been used in several models, ranging from cultured cells to transgenic animals, and now enough information has been collected to highlight advantages and pitfalls of these probes. In this review, we describe the main types of genetically encoded redox probes, their essential properties, advantages and disadvantages. We also provide an overview of the most important, in our opinion, results obtained using these probes. Finally, we discuss redox-dependent photoconversions of GFP and other prospective directions in redox probe development. Fluorescent protein-based redox probes have important advantages such as high specificity, possibility of transgenesis and fine subcellular targeting. For proper selection of a redox sensor for a particular model, it is important to understand that HyPer and roGFP2-Orp1 are the probes for H2O2, whereas roGFP1/2, rxYFP and roGFP2-Grx1 are the probes for GSH/GSSG redox state. Possible pH changes should be carefully controlled in experiments with HyPer and rxYFP. Genetically encoded redox probes are the only instruments allowing real-time monitoring of reactive oxygen species and thiol redox state in living cells and tissues. We believe that in the near future the palette of FP-based redox probes will be expanded to red and far-red parts of the spectrum and to other important reactive species such as NO, O2 and superoxide. This article is part of a Special Issue entitled

  19. Stimulus Probability Effects in Absolute Identification

    Science.gov (United States)

    Kent, Christopher; Lamberts, Koen

    2016-01-01

    This study investigated the effect of stimulus presentation probability on accuracy and response times in an absolute identification task. Three schedules of presentation were used to investigate the interaction between presentation probability and stimulus position within the set. Data from individual participants indicated strong effects of…

  20. Effect of stimulus width on simultaneous contrast

    Directory of Open Access Journals (Sweden)

    Veronica Shi

    2013-09-01

    Full Text Available Perceived brightness of a stimulus depends on the background against which the stimulus is set, a phenomenon known as simultaneous contrast. For instance, the same gray stimulus can look light against a black background or dark against a white background. Here we quantified the perceptual strength of simultaneous contrast as a function of stimulus width. Previous studies have reported that wider stimuli result in weaker simultaneous contrast, whereas narrower stimuli result in stronger simultaneous contrast. However, no previous research has quantified this relationship. Our results show a logarithmic relationship between stimulus width and perceived brightness. This relationship is well matched by the normalized output of a Difference-of-Gaussians (DOG filter applied to stimuli of varied widths.

  1. Cooperative Proxy Caching for Wireless Base Stations

    Directory of Open Access Journals (Sweden)

    James Z. Wang

    2007-01-01

    Full Text Available This paper proposes a mobile cache model to facilitate the cooperative proxy caching in wireless base stations. This mobile cache model uses a network cache line to record the caching state information about a web document for effective data search and cache space management. Based on the proposed mobile cache model, a P2P cooperative proxy caching scheme is proposed to use a self-configured and self-managed virtual proxy graph (VPG, independent of the underlying wireless network structure and adaptive to the network and geographic environment changes, to achieve efficient data search, data cache and date replication. Based on demand, the aggregate effect of data caching, searching and replicating actions by individual proxy servers automatically migrates the cached web documents closer to the interested clients. In addition, a cache line migration (CLM strategy is proposed to flow and replicate the heads of network cache lines of web documents associated with a moving mobile host to the new base station during the mobile host handoff. These replicated cache line heads provide direct links to the cached web documents accessed by the moving mobile hosts in the previous base station, thus improving the mobile web caching performance. Performance studies have shown that the proposed P2P cooperative proxy caching schemes significantly outperform existing caching schemes.

  2. Constraining trace metal paleo-proxies for black shale deposition in upwelling systems: the Benguela upwelling system offshore Namibia

    Science.gov (United States)

    Cofrancesco, J.; Riedinger, N.; Owens, J. D.

    2016-12-01

    Geochemical trace metal paleo-proxies are powerful tools for reconstructing the depositional environment of black shales. However, not all relationships and environmental conditions have been well-studied as discrepancies remain between geochemical and sedimentological proxies. While there are numerous proxies for understanding endmember redox conditions there is still a significant gap in regards to constraining oxygen minimum zones (OMZ) in ancient settings, for instance Devonian epeiric sea black shale deposits. This study aims to explore the application of geochemical and sedimentological proxies on a modern marginal marine setting - the Benguela upwelling system, offshore Namibia. This region is a modern analogue to ancient black shale formation. In this upwelling system the lateral transport of the shelf mudbelt's organic-rich sediments, deposited under anoxic (sulfidic) bottom waters, are being re-deposited under the oxygen-rich water column of the upper slope, resulting in a secondary transported organic carbon depocenter. To assess the geochemical inventory of these two different areas of organic carbon preservation, we obtained a transect of sediment cores along the shelf and slope, via the R/V MIRABILIS as a part of the 2015 Regional Graduate Network in Oceanography (RGNO) program in Namibia. The core sites were strategically sited in areas of differing water depth and redox conditions to capture a range of trace metal enrichments and organic carbon inventory. Sediments were analyzed for major elements, iron phases, and grain-size distribution. Trace metals were analyzed in the bottom water, pore water, and surface sediments. Results showed a large enrichment variation for several redox sensitive trace metals. Overall, the trace metals follow the expected trend for redox proxies, with highest enrichment in the sediments below the anoxic bottom waters. Interestingly though, some redox sensitive metals show higher enrichment in the bioturbated, mildly

  3. A statistical proxy for sulphuric acid concentration

    Directory of Open Access Journals (Sweden)

    S. Mikkonen

    2011-11-01

    Full Text Available Gaseous sulphuric acid is a key precursor for new particle formation in the atmosphere. Previous experimental studies have confirmed a strong correlation between the number concentrations of freshly formed particles and the ambient concentrations of sulphuric acid. This study evaluates a body of experimental gas phase sulphuric acid concentrations, as measured by Chemical Ionization Mass Spectrometry (CIMS during six intensive measurement campaigns and one long-term observational period. The campaign datasets were measured in Hyytiälä, Finland, in 2003 and 2007, in San Pietro Capofiume, Italy, in 2009, in Melpitz, Germany, in 2008, in Atlanta, Georgia, USA, in 2002, and in Niwot Ridge, Colorado, USA, in 2007. The long term data were obtained in Hohenpeissenberg, Germany, during 1998 to 2000. The measured time series were used to construct proximity measures ("proxies" for sulphuric acid concentration by using statistical analysis methods. The objective of this study is to find a proxy for sulfuric acid that is valid in as many different atmospheric environments as possible. Our most accurate and universal formulation of the sulphuric acid concentration proxy uses global solar radiation, SO2 concentration, condensation sink and relative humidity as predictor variables, yielding a correlation measure (R of 0.87 between observed concentration and the proxy predictions. Interestingly, the role of the condensation sink in the proxy was only minor, since similarly accurate proxies could be constructed with global solar radiation and SO2 concentration alone. This could be attributed to SO2 being an indicator for anthropogenic pollution, including particulate and gaseous emissions which represent sinks for the OH radical that, in turn, is needed for the formation of sulphuric acid.

  4. Web Proxy Auto Discovery for the WLCG

    Science.gov (United States)

    Dykstra, D.; Blomer, J.; Blumenfeld, B.; De Salvo, A.; Dewhurst, A.; Verguilov, V.

    2017-10-01

    All four of the LHC experiments depend on web proxies (that is, squids) at each grid site to support software distribution by the CernVM FileSystem (CVMFS). CMS and ATLAS also use web proxies for conditions data distributed through the Frontier Distributed Database caching system. ATLAS & CMS each have their own methods for their grid jobs to find out which web proxies to use for Frontier at each site, and CVMFS has a third method. Those diverse methods limit usability and flexibility, particularly for opportunistic use cases, where an experiment’s jobs are run at sites that do not primarily support that experiment. This paper describes a new Worldwide LHC Computing Grid (WLCG) system for discovering the addresses of web proxies. The system is based on an internet standard called Web Proxy Auto Discovery (WPAD). WPAD is in turn based on another standard called Proxy Auto Configuration (PAC). Both the Frontier and CVMFS clients support this standard. The input into the WLCG system comes from squids registered in the ATLAS Grid Information System (AGIS) and CMS SITECONF files, cross-checked with squids registered by sites in the Grid Configuration Database (GOCDB) and the OSG Information Management (OIM) system, and combined with some exceptions manually configured by people from ATLAS and CMS who operate WLCG Squid monitoring. WPAD servers at CERN respond to http requests from grid nodes all over the world with a PAC file that lists available web proxies, based on IP addresses matched from a database that contains the IP address ranges registered to organizations. Large grid sites are encouraged to supply their own WPAD web servers for more flexibility, to avoid being affected by short term long distance network outages, and to offload the WLCG WPAD servers at CERN. The CERN WPAD servers additionally support requests from jobs running at non-grid sites (particularly for LHC@Home) which they direct to the nearest publicly accessible web proxy servers. The responses

  5. Redox Properties of Free Radicals.

    Science.gov (United States)

    Neta, P.

    1981-01-01

    Describes pulse radiolysis as a useful means in studing one-electron redox potentials. This method allows the production of radicals and the determination of their concentration and rates of reaction. (CS)

  6. Munchausen Syndrome by Proxy: Medical Diagnostic Criteria.

    Science.gov (United States)

    Rosenberg, Donna Andrea

    2003-01-01

    Medical diagnostic criteria for Munchausen Syndrome by Proxy (a persistent fabrication by one individual of illness in another) are presented. Since the strength of the known facts may vary from case to case, diagnostic criteria are given for a definitive diagnosis, a possible diagnosis, an inconclusive determination, and the definitely excluded…

  7. Munchausen Syndrome by Proxy: Evaluation and Treatment.

    Science.gov (United States)

    Parnell, Teresa F.; Day, Deborah O.

    Munchausen Syndrome by Proxy (MSBP) is characterized by a significant caretaker, usually a mother, deliberately inducing and/or falsely reporting illness in a child. The potentially fatal outcome of undetected MSBP makes the understanding of this syndrome gravely important. Early detection and effective intervention can be accomplished through the…

  8. Munchausen Syndrome by Proxy: Social Work's Role.

    Science.gov (United States)

    Mercer, Susan O.; Perdue, Jeanette D.

    1993-01-01

    Describes Munchausen syndrome by proxy, diagnosis used to describe variation of child abuse whereby parent or adult caregiver fabricates medical history or induces symptoms in child, or both, resulting in unnecessary examinations, treatments, hospitalizations, and even death. Reviews assessment procedures, provides case studies, and describes…

  9. Munchausen Syndrome by Proxy: A Family Affair.

    Science.gov (United States)

    Mehl, Albert L.; And Others

    1990-01-01

    The article reports on a case of Munchausen syndrome by proxy in which chronic illicit insulin was administered to a one-year-old child by her mother. Factitious illnesses continued despite psychiatric intervention. Retrospective review of medical records suggested 30 previous episodes of factitious illness within the family. (DB)

  10. The Syndrome of Munchausen by Proxy.

    Science.gov (United States)

    Jones, David P. H.

    1994-01-01

    This editorial introduces two articles on Munchausen by Proxy syndrome (the induction of an appearance or state of physical ill health in a child, by the caretaker, and the child's subsequent presentation to health professionals for diagnosis and/or treatment). The severity of the caretaker's psychological disturbance and the serious effects on…

  11. Improving Internet Archive Service through Proxy Cache.

    Science.gov (United States)

    Yu, Hsiang-Fu; Chen, Yi-Ming; Wang, Shih-Yong; Tseng, Li-Ming

    2003-01-01

    Discusses file transfer protocol (FTP) servers for downloading archives (files with particular file extensions), and the change to HTTP (Hypertext transfer protocol) with increased Web use. Topics include the Archie server; proxy cache servers; and how to improve the hit rate of archives by a combination of caching and better searching mechanisms.…

  12. Occlusion for stimulus deprivation amblyopia

    Science.gov (United States)

    Antonio-Santos, Aileen; Vedula, Satyanarayana S; Hatt, Sarah R; Powell, Christine

    2014-01-01

    Background Stimulus deprivation amblyopia (SDA) develops due to an obstruction to the passage of light secondary to a condition such as cataract. The obstruction prevents formation of a clear image on the retina. SDA can be resistant to treatment, leading to poor visual prognosis. SDA probably constitutes less than 3% of all amblyopia cases, although precise estimates of prevalence are unknown. In developed countries, most patients present under the age of one year; in less developed parts of the world patients are likely to be older at the time of presentation. The mainstay of treatment is removal of the cataract and then occlusion of the better-seeing eye, but regimens vary, can be difficult to execute, and traditionally are believed to lead to disappointing results. Objectives Our objective was to evaluate the effectiveness of occlusion therapy for SDA in an attempt to establish realistic treatment outcomes. Where data were available, we also planned to examine evidence of any dose response effect and to assess the effect of the duration, severity, and causative factor on the size and direction of the treatment effect. Search methods We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2013, Issue 9), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to October 2013), EMBASE (January 1980 to October 2013), the Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to October 2013), PubMed (January 1946 to October 2013), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 28 October 2013. Selection criteria We planned

  13. EEG Differentiation Analysis and Stimulus Set Meaningfulness.

    Science.gov (United States)

    Mensen, Armand; Marshall, William; Tononi, Giulio

    2017-01-01

    A set of images can be considered as meaningfully different for an observer if they can be distinguished phenomenally from one another. Each phenomenal difference must be supported by some neurophysiological differences. Differentiation analysis aims to quantify neurophysiological differentiation evoked by a given set of stimuli to assess its meaningfulness to the individual observer. As a proof of concept using high-density EEG, we show increased neurophysiological differentiation for a set of natural, meaningfully different images in contrast to another set of artificially generated, meaninglessly different images in nine participants. Stimulus-evoked neurophysiological differentiation (over 257 channels, 800 ms) was systematically greater for meaningful vs. meaningless stimulus categories both at the group level and for individual subjects. Spatial breakdown showed a central-posterior peak of differentiation, consistent with the visual nature of the stimulus sets. Temporal breakdown revealed an early peak of differentiation around 110 ms, prominent in the central-posterior region; and a later, longer-lasting peak at 300-500 ms that was spatially more distributed. The early peak of differentiation was not accompanied by changes in mean ERP amplitude, whereas the later peak was associated with a higher amplitude ERP for meaningful images. An ERP component similar to visual-awareness-negativity occurred during the nadir of differentiation across all image types. Control stimulus sets and further analysis indicate that changes in neurophysiological differentiation between meaningful and meaningless stimulus sets could not be accounted for by spatial properties of the stimuli or by stimulus novelty and predictability.

  14. Legal requirements governing proxy voting in Denmark

    DEFF Research Database (Denmark)

    Werlauff, Erik

    2008-01-01

    The requirements in Danish company law concerning proxy voting in companies whose shares have been accepted for listing on a regulated market have been successively tightened in recent years, and corporate governance principles have also led to the introduction of several requirements concerning...... proxy holders. A thorough knowledge of these requirements is important not only for the listed companies but also for their advisers and investors in Denmark and abroad. This article considers these requirements as well as the additional requirements which will derive from Directive 2007....../36 on the exercise of shareholders' rights in listed companies, which must be implemented by 3 August 2009. It is pointed out that companies may provide with advantage in their articles of association for both the existing and the forthcoming requirements at this early stage....

  15. Observable Proxies For 26 Al Enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Fryer, Christopher L [Los Alamos National Laboratory; Young, Patrick A [Los Alamos National Laboratory; Ellinger, Carola I [ASU; Arnett, William D [UNIV ARIZONA

    2008-01-01

    We consider the cospatial production of elements in supernova explosions to find observationally detectable proxies for enhancement of {sup 26}Al in supernova ejecta and stellar systems. Using four progenitors we explore a range of 1D explosions at different energies and an asymmetric 3D explosion. We find that the most reliable indicator of the presence of {sup 26}Al in unmixed ejecta is a very low S/Si ratio ({approx} 0.05). Production of N in O/S/Si-rich regions is also indicative. The biologically important element P is produced at its highest abundance in the same regions. Proxies should be detectable in supernova ejecta with high spatial resolution multi wavelength observations, but the small absolute abundance of material injected into a proto-planetary disk makes detection unlikely in existing or forming stellar/planetary systems.

  16. Non-destructive foraminiferal paleoclimatic proxies: A brief insight

    Digital Repository Service at National Institute of Oceanography (India)

    Saraswat, R.

    Non-Destructive Foraminiferal Paleoclimatic Proxies: A Brief Insight The knowledge of past climate can help us to understand imminent climatic changes. Oceans are the vast archives of past climate. Various indirect techniques termed as proxies...

  17. Implementasi Proxy Server Dengan Linux Clear OS 5.2

    OpenAIRE

    Setiadi, Aprian

    2013-01-01

    Tugas Akhir ini membahas mengenai cara untuk membangun sebuah proxy server dalam jaringan LAN. Jaringan LAN yang dibangun menggunakan arsitektur topologi star dengan menjadikan komputer server sebagai Gateway Server dan Proxy Server, sehingga tidak membutuhkan perangkat tambahan Router yang berfungsi sebagai Gateway Server. Proxy Server yang yang dibangun menggunakan metode Transparent Mode, sehingga pada komputer klien tidak perlu mengkonfigurasi port proxy server pada Web Browser. Hasil ya...

  18. ERP components related to stimulus selection processes.

    Science.gov (United States)

    Paz-Caballero, M D; García-Austt, E

    1992-05-01

    Event-related potential (ERP) components associated with target stimulus selection in a double discrimination visual task were studied. The experimental paradigm consisted in the presentation of low intensity stimuli that varied according to two physical features: geometrical form (squares and circles) and location (a spot in different positions inside the stimulus). Subjects performed 3 tasks on these stimuli: control task in which they looked passively at the stimuli, and 2 discrimination tasks, in which they had to respond to a certain stimulus (a specific conjunction of form and spot location). The early components (P1 and N1) obtained in the control and discrimination tasks were associated with sensory analysis of simple stimulus features. Relevance of a particular feature modified the latency and/or the area of these components. The longer-latency components (N2 and P3) were elicited only in the discrimination tasks. N2 was associated with target stimulus selection because its area was significantly larger for target stimuli and because its "offset" latency correlated with choice reaction time. Results are discussed and contrasted with various models of target selection.

  19. Defining the stimulus--a memoir.

    Science.gov (United States)

    Terrace, Herbert

    2010-02-01

    The eminent psychophysicist, S.S. Stevens, once remarked that, "the basic problem of psychology was the definition of the stimulus" (Stevens, 1951, p. 46). By expanding the traditional definition of the stimulus, the study of animal learning has metamorphosed into animal cognition. The main impetus for that change was the recognition that it is often necessary to postulate a representation between the traditional S and R of learning theory. Representations allow a subject to represent a stimulus it learned previously that is currently absent. Thus, in delayed matching-to-sample, one has to assume that a subject responds to a representation of the sample during test if it responds correctly. Other examples, to name but a few, include concept formation, spatial memory, serial memory, learning a numerical rule, imitation and metacognition. Whereas a representation used to be regarded as a mentalistic phenomenon that was unworthy of scientific inquiry, it can now be operationally defined. To accommodate representations, the traditional discriminative stimulus has to be expanded to allow for the role of representations. The resulting composite can account for a significantly larger portion of the variance of performance measures than the exteroceptive stimulus could by itself. Copyright 2009 Elsevier B.V. All rights reserved.

  20. 12 CFR 7.2002 - Director or attorney as proxy.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 1 2010-01-01 2010-01-01 false Director or attorney as proxy. 7.2002 Section 7... OPERATIONS Corporate Practices § 7.2002 Director or attorney as proxy. Any person or group of persons, except the bank's officers, clerks, tellers, or bookkeepers, may be designated to act as proxy. The bank's...

  1. Physicians' Involvement with the New York State Health Care Proxy

    Science.gov (United States)

    Heyman, Janna C.; Sealy, Yvette M.

    2011-01-01

    This study examined physicians' attitude, involvement, and perceived barriers with the health care proxy. A cross sectional, correlational design was used to survey practicing physicians (N = 70). Physicians had positive attitudes toward the health care proxy and indicated that the most significant barriers to health care proxy completion were…

  2. Redox Pioneer: Professor Joseph Loscalzo

    OpenAIRE

    Leopold, Jane A.

    2010-01-01

    Dr. Joseph Loscalzo (M.D., 1978; Ph.D., 1977) is recognized here as a Redox Pioneer because he has published two articles in the field of antioxidant/redox biology that have been cited more than 1,000 times and 22 articles that have been cited more than 100 times. Dr. Loscalzo is known for his seminal contributions to our understanding of the vascular biology of nitric oxide. His initial discovery that the antiplatelet effects of organic nitrates are potentiated by thiols through a mechanism ...

  3. Stimulus generalization of a positive conditioned reinforcer.

    Science.gov (United States)

    THOMAS, D R; WILLIAMS, J L

    1963-07-12

    Stimulus generalization has been observed for discriminative, eliciting, and emotional functions of stimuli. In our study, in order to investigate the generalization of the reinforcing function of stimuli, pigeons were trained in a Skinner box to peck at an unlighted key to obtain aperiodic, brief exposures of light at a wavelength of 550 mmicro, the positive conditioned reinforcer, which was immediately followed by food reward. Testing in extinction, we obtained generalization gradients for the number of responses and the time the pigeons expended to produce exposures on the unlighted key of 550 mmicro, 530 mmicro) 510 mmicro, or no light. This finding suggests that stimulus generalization occurs with all functions of stimuli.

  4. Redox stratification of an ancient lake in Gale crater, Mars

    Science.gov (United States)

    Hurowitz, J. A.; Grotzinger, J. P.; Fischer, W. W.; McLennan, S. M.; Milliken, R. E.; Stein, N.; Vasavada, A. R.; Blake, D. F.; Dehouck, E.; Eigenbrode, J. L.; Fairén, A. G.; Frydenvang, J.; Gellert, R.; Grant, J. A.; Gupta, S.; Herkenhoff, K. E.; Ming, D. W.; Rampe, E. B.; Schmidt, M. E.; Siebach, K. L.; Stack-Morgan, K.; Sumner, D. Y.; Wiens, R. C.

    2017-06-01

    In 2012, NASA's Curiosity rover landed on Mars to assess its potential as a habitat for past life and investigate the paleoclimate record preserved by sedimentary rocks inside the ~150-kilometer-diameter Gale impact crater. Geological reconstructions from Curiosity rover data have revealed an ancient, habitable lake environment fed by rivers draining into the crater. We synthesize geochemical and mineralogical data from lake-bed mudstones collected during the first 1300 martian solar days of rover operations in Gale. We present evidence for lake redox stratification, established by depth-dependent variations in atmospheric oxidant and dissolved-solute concentrations. Paleoclimate proxy data indicate that a transition from colder to warmer climate conditions is preserved in the stratigraphy. Finally, a late phase of geochemical modification by saline fluids is recognized.

  5. Redox stratification of an ancient lake in Gale crater, Mars.

    Science.gov (United States)

    Hurowitz, J A; Grotzinger, J P; Fischer, W W; McLennan, S M; Milliken, R E; Stein, N; Vasavada, A R; Blake, D F; Dehouck, E; Eigenbrode, J L; Fairén, A G; Frydenvang, J; Gellert, R; Grant, J A; Gupta, S; Herkenhoff, K E; Ming, D W; Rampe, E B; Schmidt, M E; Siebach, K L; Stack-Morgan, K; Sumner, D Y; Wiens, R C

    2017-06-02

    In 2012, NASA's Curiosity rover landed on Mars to assess its potential as a habitat for past life and investigate the paleoclimate record preserved by sedimentary rocks inside the ~150-kilometer-diameter Gale impact crater. Geological reconstructions from Curiosity rover data have revealed an ancient, habitable lake environment fed by rivers draining into the crater. We synthesize geochemical and mineralogical data from lake-bed mudstones collected during the first 1300 martian solar days of rover operations in Gale. We present evidence for lake redox stratification, established by depth-dependent variations in atmospheric oxidant and dissolved-solute concentrations. Paleoclimate proxy data indicate that a transition from colder to warmer climate conditions is preserved in the stratigraphy. Finally, a late phase of geochemical modification by saline fluids is recognized. Copyright © 2017, American Association for the Advancement of Science.

  6. Carving Executive Control At Its Joints: Working Memory Capacity Predicts Stimulus-Stimulus, But Not Stimulus-Response, Conflict

    Science.gov (United States)

    Meier, Matt E.; Kane, Michael J.

    2015-01-01

    Three experiments examined the relation between working memory capacity (WMC) and two different forms of cognitive conflict: stimulus-stimulus (S-S) and stimulus-response (SR) interference. Our goal was to test whether WMC’s relation to conflict-task performance is mediated by stimulus-identification processes (captured by S-S conflict), response-selection processes (captured by S-R conflict), or both. In Experiment 1, subjects completed a single task presenting both S-S and S-R conflict trials, plus trials that combined the two conflict types. We limited ostensible goal-maintenance contributions to performance by requiring the same goal for all trial types and by presenting frequent conflict trials that reinforced the goal. WMC predicted resolution of S-S conflict as expected: Higher-WMC subjects showed reduced response time interference. Although WMC also predicted S-R interference, here, higher-WMC subjects showed increased error interference. Experiment 2A replicated these results in a version of the conflict task without combined S-S/S-R trials. Experiment 2B increased the proportion of congruent (non-conflict) trials to promote reliance on goal-maintenance processes. Here, higher-WMC subjects resolved both S-S and S-R conflict more successfully than did lower-WMC subjects. The results were consistent with Kane and Engle’s (2003) two-factor theory of cognitive control, according to which WMC predicts executive-task performance through goal-maintenance and conflict-resolution processes. However, the present results add specificity to the account by suggesting that higher-WMC subjects better resolve cognitive conflict because they more efficiently select relevant stimulus features against irrelevant, distracting ones. PMID:26120774

  7. Proxy Graph: Visual Quality Metrics of Big Graph Sampling.

    Science.gov (United States)

    Nguyen, Quan Hoang; Hong, Seok-Hee; Eades, Peter; Meidiana, Amyra

    2017-06-01

    Data sampling has been extensively studied for large scale graph mining. Many analyses and tasks become more efficient when performed on graph samples of much smaller size. The use of proxy objects is common in software engineering for analysis and interaction with heavy objects or systems. In this paper, we coin the term 'proxy graph' and empirically investigate how well a proxy graph visualization can represent a big graph. Our investigation focuses on proxy graphs obtained by sampling; this is one of the most common proxy approaches. Despite the plethora of data sampling studies, this is the first evaluation of sampling in the context of graph visualization. For an objective evaluation, we propose a new family of quality metrics for visual quality of proxy graphs. Our experiments cover popular sampling techniques. Our experimental results lead to guidelines for using sampling-based proxy graphs in visualization.

  8. Electrical Microengineering of Redox Enzymes

    Science.gov (United States)

    1994-03-31

    as cytochrome c, myoglobin. ferredoxin and phycocyanin ) has been studied by Kuwana, Hill, Hawkridgc. Blount, Bowden. Armstrong and their colleagues.4...shell- around their redox centers. (such as cytochrome c,A h wu w AN uv. myoglobin. ferredoxin and phycocyanin ) ha•e also shown that. e~en though these

  9. Stimulus-classification and stimulus-action associations: Effects of repetition learning and durability.

    Science.gov (United States)

    Moutsopoulou, Karolina; Yang, Qing; Desantis, Andrea; Waszak, Florian

    2015-01-01

    It has been shown that acquired stimulus-response bindings result from at least two types of associations from the stimulus to the task (stimulus-task or stimulus-classification; S-C) and from the stimulus to the motor response (stimulus-response or stimulus-action; S-A). These types of associations have been shown to independently affect behaviour. This finding suggests that they are processed in different pathways or different parts of a pathway at the neural level. Here we test a hypothesis that such associations may be differentially affected by repetition learning and that such effects may be detected by measuring their durability against overwriting. We show that both S-C and S-A associations are in fact strengthened when learning is boosted by increasing repetitions of the primes. However, the results further suggest that associations between stimuli and actions have less durable effects on behaviour and that the durability of S-C and S-A associations is independent of repetition learning. This is an important finding for the understanding of the underlying mechanisms of associative learning and particularly raises the question of which processes may affect flexibility of learning.

  10. Adaptability in CORBA: The Mobile Proxy Approach

    DEFF Research Database (Denmark)

    Aziz, B.; Jensen, Christian D.

    2000-01-01

    are inherently open, heterogeneous, and dynamic environments integrating a wide range of platforms, operating systems and applications from a number of different sources. In this paper, we propose to use mobile proxies to provide adaptability in distributed applications integrated using the CORBA technology......Adaptability is one of the most important challenges in modern distributed systems. It may be defined as the ease with which a software application satisfies the different system constraints and the requirements of users and other applications. Adaptability is needed because distributed systems...

  11. Stimulus Configuration, Classical Conditioning, and Hippocampal Function.

    Science.gov (United States)

    Schmajuk, Nestor A.; DiCarlo, James J.

    1991-01-01

    The participation of the hippocampus in classical conditioning is described in terms of a multilayer network portraying stimulus configuration. A model of hippocampal function is presented, and computer simulations are used to study neural activity in the various brain areas mapped according to the model. (SLD)

  12. Coding stimulus amplitude by correlated neural activity.

    Science.gov (United States)

    Metzen, Michael G; Ávila-Åkerberg, Oscar; Chacron, Maurice J

    2015-04-01

    While correlated activity is observed ubiquitously in the brain, its role in neural coding has remained controversial. Recent experimental results have demonstrated that correlated but not single-neuron activity can encode the detailed time course of the instantaneous amplitude (i.e., envelope) of a stimulus. These have furthermore demonstrated that such coding required and was optimal for a nonzero level of neural variability. However, a theoretical understanding of these results is still lacking. Here we provide a comprehensive theoretical framework explaining these experimental findings. Specifically, we use linear response theory to derive an expression relating the correlation coefficient to the instantaneous stimulus amplitude, which takes into account key single-neuron properties such as firing rate and variability as quantified by the coefficient of variation. The theoretical prediction was in excellent agreement with numerical simulations of various integrate-and-fire type neuron models for various parameter values. Further, we demonstrate a form of stochastic resonance as optimal coding of stimulus variance by correlated activity occurs for a nonzero value of noise intensity. Thus, our results provide a theoretical explanation of the phenomenon by which correlated but not single-neuron activity can code for stimulus amplitude and how key single-neuron properties such as firing rate and variability influence such coding. Correlation coding by correlated but not single-neuron activity is thus predicted to be a ubiquitous feature of sensory processing for neurons responding to weak input.

  13. Bigrams and the Richness of the Stimulus

    Science.gov (United States)

    Kam, Xuan-Nga Cao; Stoyneshka, Iglika; Tornyova, Lidiya; Fodor, Janet D.; Sakas, William G.

    2008-01-01

    Recent challenges to Chomsky's "poverty of the stimulus" thesis for language acquisition suggest that children's primary data may carry "indirect evidence" about linguistic constructions despite containing no instances of them. Indirect evidence is claimed to suffice for grammar acquisition, without need for innate knowledge. This article reports…

  14. The Poverty of the Mayan Stimulus

    Science.gov (United States)

    Pye, Clifton

    2012-01-01

    Poverty of the stimulus (POS) arguments have instigated considerable debate in the recent linguistics literature. This article uses the comparative method to challenge the logic of POS arguments. Rather than question the premises of POS arguments, the article demonstrates how POS arguments for individual languages lead to a "reductio ad absurdum"…

  15. Economic Stimulus Proposals for 2008: An Analysis

    National Research Council Canada - National Science Library

    Gravelle, Jane G; Hungerford, Thomas L; Labonte, Marc; Weiss, N. E; Whittaker, Julie M

    2008-01-01

    ...) was introduced and passed by the House on January 29. On January 30, the Senate Committee on Finance reported the Economic Stimulus Act of 2008, which contains provisions not included in the House bill, as well as elements that are similar...

  16. Stimulus polarity and conditioning in planaria.

    Science.gov (United States)

    BARNES, C D; KATZUNG, B G

    1963-08-23

    Orientation in the monopolar pulse field used as the unconditioned stimulus was found to influence formation of a conditioned response to light in planarians. Planarians trained while oriented with the head toward the cathode reached maximal response rates rapidly, while those trained while oriented toward the anode showed no evidence of conditioned response formation.

  17. Crisis, Stimulus Package and Migration in China

    NARCIS (Netherlands)

    Csanádi, Maria; Nie, Zihan; Li, Shi

    2015-01-01

    This paper analyzes the short-term and long-term effects that the global economic crisis and the investment priorities of the Chinese Government's stimulus package had on Chinese migrant flows between 2008 and 2014. Combining micro-level household survey data and macro-level statistics, the

  18. Contextual dependencies in a stimulus equivalence paradigm

    NARCIS (Netherlands)

    Dibbets, P.; Maes, J.H.R.; Vossen, J.M.H.

    2002-01-01

    Two experiments with human subjects assessed contextual dependencies in a stimulus equivalence paradigm. Subjects learned to form two sets of stimuli in a matching-to-sample training procedure. Each set was presented against one of two different background colours, the contextual cues. At test, the

  19. Appraising timing response of paleoenvironmental proxies to the Bond cycle in the western Mediterranean over the last 20 kyr

    Science.gov (United States)

    Rodrigo-Gámiz, Marta; Martínez-Ruiz, Francisca; Rodríguez-Tovar, Francisco J.; Pardo-Igúzquiza, Eulogio; Ortega-Huertas, Miguel

    2017-07-01

    The timing of climate responses to the Bond cycle is investigated in the western Mediterranean. Periodicities had been previously reported in a marine sediment record from this region spanning the last 20 kyr, and registered by diverse paleoenvironmental proxies, in particular those associated with terrigenous input, redox conditions, productivity, sea surface temperature (SST) and salinity. Further cross-spectral analyses on these time series reveal leads-lags in the 1400 year climate cycle. Considering as reference a terrigenous input proxy (the K/Al ratio), all the paleoenvironmental proxies displayed time shifts varying from ca. 700 year to ca. 350 year. SST and salinity variations show a first leaded response with the inflow of cold and less salty Atlantic waters. Followed by a time lead of 525 year, progresively arid conditions with an increase of eolian dust transport to the area, given by the Zr/Al signal, are observed. The intensification of dust transport could have triggered a latest biological response, lead by 350 year, with an increase of productivity, as suggested by the Ba/Al ratio. Lastly changes in the Mediterranean thermohaline circulation, indicated by a selected redox proxy (the U/Th ratio), are observed. These results support that the oceanic response triggered the atmospheric response to the Bond cycle in the western Mediterranean. Changes in the North Atlantic Oscillation mode and in the Inter-Tropical Convergence Zone migrations with variations in the monsoon activity or Saharan winds system, are considered as main forcing mechanisms, with a complex relationship of the involved phenomena.

  20. Munchausen syndrome by proxy: ongoing clinical challenges.

    Science.gov (United States)

    Squires, Janet E; Squires, Robert H

    2010-09-01

    In 1977, Roy Meadow, a pediatric nephrologist, first described a condition he subsequently coined Munchausen syndrome by proxy. The classic form involves a parent or other caregiver who inflicts injury or induces illness in a child, deceive the treating physician with fictitious or exaggerated information, and perpetrate the trick for months or years. A related form of pathology is more insidious and more common but also damaging. It involves parents who fabricate or exaggerate symptoms of illness in children, causing overly aggressive medical evaluations and interventions. The common thread is that the treating physician plays a role in inflicting the abuse upon the child. Failure to recognize the problem is common because the condition is often not included in the differential diagnosis of challenging or confusing clinical problems. We believe that a heightened "self-awareness" of the physician's role in Munchausen syndrome by proxy will prevent or reduce the morbidity and mortality associated with this diagnosis. In addition, we believe contemporary developments within the modern health care system likely facilitate this condition.

  1. The Effect of Stimulus Size on the Reliable Stimulus Range of Perimetry.

    Science.gov (United States)

    Gardiner, Stuart K; Demirel, Shaban; Goren, Deborah; Mansberger, Steven L; Swanson, William H

    2015-03-01

    Automated perimetry uses a 3.5 log unit (35dB) range of stimulus contrasts to assess function within the visual field. Using 'Size III' stimuli (0.43°), presenting stimuli within the highest 15dB of available contrast may not increase the response probability at locations damaged by glaucoma, due to retinal ganglion cell response saturation. This experiment examines the effect of instead using 'Size V' (1.72°) stimuli. Luminance increment thresholds for circular spot stimuli of each stimulus size were measured in 35 participants (mean deviation -20.9 to -3.4 dB, ages 52-87) using the method of constant stimuli, at four locations per participant. Frequency-of-seeing curves were fit at each size and location, with three free parameters: mean, standard deviation, and asymptotic maximum response probability. These were used to estimate the contrasts to which each participant would respond on 25% of presentations (c25). Using segmented orthogonal regression, the maximum observed response probabilities for size III stimuli began to decline at c25 = 25.2 dB (95% confidence interval 23.3-29.0 dB from bootstrap resampling). This decline started at similar contrast for the size V stimulus: c25 = 25.0dB (22.0-26.8 dB). Among locations at which the sensitivity was above these split-points for both stimulus sizes, c25 averaged 5.6 dB higher for size V than size III stimuli. The lower limit of the reliable stimulus range did not differ significantly between stimulus sizes. However, more locations remained within the reliable stimulus range when using the size V stimulus. Size V stimuli enable reliable clinical testing later into the glaucomatous disease process.

  2. Development and Applications of Thallium isotopes: a new proxy tracking the extent of manganese oxide burial

    Science.gov (United States)

    Owens, J. D.; Nielsen, S.; Ostrander, C.; Peterson, L. C.; Anbar, A. D.

    2015-12-01

    Thallium (Tl) isotopes are a new and potential powerful paleoredox proxy with the possibility to track bottom water oxygen conditions based on the burial flux of manganese oxides. Thallium has a residence time of ~20 thousand years, which is long enough to render modern oxic seawater conservative with respect to concentration and isotopes. The isotopic signature of Tl in the global ocean is driven mainly by two outputs (1) adsorption onto manganese oxides and (2) low temperature oceanic crust alteration. Importantly, the isotopic inputs of Tl are all nearly the same value; thus, the isotopic composition and flux of the outputs almost exclusively set the seawater signature. For relatively short term redox events it is reasonable to assume that the dominant isotope fractionation process is associated with manganese oxide precipitation because low temperature alteration is controlled by long-term average ocean crust production rates. We present a broad range of modern samples that span several open ocean profiles combined with water column and sediment profiles from the permanently anoxic basins of the Black Sea and Cariaco Basins. The open ocean shows no variation in depth profiles that encompass most of the major water masses in the Atlantic and Southern Oceans. The anoxic basins, however, reveal Tl isotope signatures closer to their inputs, which is likely due to basinal restriction. The authigenic fraction of organic-rich sediments from the Black Sea and Cariaco Basin capture the Tl isotope value of the overlying water column, which shows that Tl isotopes could be applied as a faithful deep time redox proxy. For the first time, we will present new data showing that Tl isotopes is tracking bottom water ocean oxygenation. We are applying this isotope system to ancient samples, testing the spatial and temporal variability of ocean oxygenation coinciding with major biogeochemical events.

  3. Redox signaling in acute pancreatitis

    Science.gov (United States)

    Pérez, Salvador; Pereda, Javier; Sabater, Luis; Sastre, Juan

    2015-01-01

    Acute pancreatitis is an inflammatory process of the pancreatic gland that eventually may lead to a severe systemic inflammatory response. A key event in pancreatic damage is the intracellular activation of NF-κB and zymogens, involving also calcium, cathepsins, pH disorders, autophagy, and cell death, particularly necrosis. This review focuses on the new role of redox signaling in acute pancreatitis. Oxidative stress and redox status are involved in the onset of acute pancreatitis and also in the development of the systemic inflammatory response, being glutathione depletion, xanthine oxidase activation, and thiol oxidation in proteins critical features of the disease in the pancreas. On the other hand, the release of extracellular hemoglobin into the circulation from the ascitic fluid in severe necrotizing pancreatitis enhances lipid peroxidation in plasma and the inflammatory infiltrate into the lung and up-regulates the HIF–VEGF pathway, contributing to the systemic inflammatory response. Therefore, redox signaling and oxidative stress contribute to the local and systemic inflammatory response during acute pancreatitis. PMID:25778551

  4. Understanding smell--the olfactory stimulus problem.

    Science.gov (United States)

    Auffarth, Benjamin

    2013-09-01

    The main problem with sensory processing is the difficulty in relating sensory input to physiological responses and perception. This is especially problematic at higher levels of processing, where complex cues elicit highly specific responses. In olfaction, this relationship is particularly obfuscated by the difficulty of characterizing stimulus statistics and perception. The core questions in olfaction are hence the so-called stimulus problem, which refers to the understanding of the stimulus, and the structure-activity and structure-odor relationships, which refer to the molecular basis of smell. It is widely accepted that the recognition of odorants by receptors is governed by the detection of physico-chemical properties and that the physical space is highly complex. Not surprisingly, ideas differ about how odor stimuli should be classified and about the very nature of information that the brain extracts from odors. Even though there are many measures for smell, there is none that accurately describes all aspects of it. Here, we summarize recent developments in the understanding of olfaction. We argue that an approach to olfactory function where information processing is emphasized could contribute to a high degree to our understanding of smell as a perceptual phenomenon emerging from neural computations. Further, we argue that combined analysis of the stimulus, biology, physiology, and behavior and perception can provide new insights into olfactory function. We hope that the reader can use this review as a competent guide and overview of research activities in olfactory physiology, psychophysics, computation, and psychology. We propose avenues for research, particularly in the systematic characterization of receptive fields and of perception. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Teori Stres: Stimulus, Respons, dan Transaksional

    OpenAIRE

    Nasib Tua Lumban Gaol

    2016-01-01

    Understanding the fundamental concept of stress is necessary due to it leads to comprehending deeply regarding what stress is. Principally, there models of stress confirm what stress is and how stress occurs on human. First, the stimulus model of stress is the treating environments that stimulate individual to perceive stress. Second, the response model of stress is a bodily reaction to the source of stress. Third, the transactional model of stress is the evaluation process to the sources of ...

  6. Workflows for intelligent monitoring using proxy services.

    Science.gov (United States)

    Rüping, Stefan; Wegener, Dennis; Sfakianakis, Stelios; Sengstag, Thierry

    2009-01-01

    Grid technologies have proven to be very successful in the area of eScience, and in particular in healthcare applications. But while the applicability of workflow enacting tools for biomedical research has long since been proven, the practical adoption into regular clinical research has some additional challenges in grid context. In this paper, we investigate the case of data monitoring, and how to seamlessly implement the step between a one-time proof-of-concept workflow and high-performance on-line monitoring of data streams, as exemplified by the case of long-running clinical trials. We will present an approach based on proxy services that allows executing single-run workflows repeatedly with little overhead.

  7. Salmon: Robust Proxy Distribution for Censorship Circumvention

    Directory of Open Access Journals (Sweden)

    Douglas Frederick

    2016-10-01

    Full Text Available Many governments block their citizens’ access to much of the Internet. Simple workarounds are unreliable; censors quickly discover and patch them. Previously proposed robust approaches either have non-trivial obstacles to deployment, or rely on low-performance covert channels that cannot support typical Internet usage such as streaming video. We present Salmon, an incrementally deployable system designed to resist a censor with the resources of the “Great Firewall” of China. Salmon relies on a network of volunteers in uncensored countries to run proxy servers. Although any member of the public can become a user, Salmon protects the bulk of its servers from being discovered and blocked by the censor via an algorithm for quickly identifying malicious users. The algorithm entails identifying some users as especially trustworthy or suspicious, based on their actions. We impede Sybil attacks by requiring either an unobtrusive check of a social network account, or a referral from a trustworthy user.

  8. Stimulus and transducer effects on threshold.

    Science.gov (United States)

    Flamme, Gregory A; Geda, Kyle; McGregor, Kara D; Wyllys, Krista; Deiters, Kristy K; Murphy, William J; Stephenson, Mark R

    2015-02-01

    This study examined differences in thresholds obtained under Sennheiser HDA200 circumaural earphones using pure tone, equivalent rectangular noise bands, and 1/3 octave noise bands relative to thresholds obtained using Telephonics TDH-39P supra-aural earphones. Thresholds were obtained via each transducer and stimulus condition six times within a 10-day period. Forty-nine adults were selected from a prior study to represent low, moderate, and high threshold reliability. The results suggested that (1) only small adjustments were needed to reach equivalent TDH-39P thresholds, (2) pure-tone thresholds obtained with HDA200 circumaural earphones had reliability equal to or better than those obtained using TDH-39P earphones, (3) the reliability of noise-band thresholds improved with broader stimulus bandwidth and was either equal to or better than pure-tone thresholds, and (4) frequency-specificity declined with stimulus bandwidths greater than one equivalent rectangular band, which could complicate early detection of hearing changes that occur within a narrow frequency range. These data suggest that circumaural earphones such as the HDA200 headphones provide better reliability for audiometric testing as compared to the TDH-39P earphones. These data support the use of noise bands, preferably ERB noises, as stimuli for audiometric monitoring.

  9. Performance breakdown in optimal stimulus decoding.

    Science.gov (United States)

    Lubomir Kostal; Lansky, Petr; Pilarski, Stevan

    2015-06-01

    One of the primary goals of neuroscience is to understand how neurons encode and process information about their environment. The problem is often approached indirectly by examining the degree to which the neuronal response reflects the stimulus feature of interest. In this context, the methods of signal estimation and detection theory provide the theoretical limits on the decoding accuracy with which the stimulus can be identified. The Cramér-Rao lower bound on the decoding precision is widely used, since it can be evaluated easily once the mathematical model of the stimulus-response relationship is determined. However, little is known about the behavior of different decoding schemes with respect to the bound if the neuronal population size is limited. We show that under broad conditions the optimal decoding displays a threshold-like shift in performance in dependence on the population size. The onset of the threshold determines a critical range where a small increment in size, signal-to-noise ratio or observation time yields a dramatic gain in the decoding precision. We demonstrate the existence of such threshold regions in early auditory and olfactory information coding. We discuss the origin of the threshold effect and its impact on the design of effective coding approaches in terms of relevant population size.

  10. Impact of stimulus uncanniness on speeded response

    Directory of Open Access Journals (Sweden)

    Kohske eTakahashi

    2015-05-01

    Full Text Available In the uncanny valley phenomenon, the causes of the feeling of uncanniness as well as the impact of the uncanniness on behavioral performances still remain open. The present study investigated the behavioral effects of stimulus uncanniness, particularly with respect to speeded response. Pictures of fish were used as visual stimuli. Participants engaged in direction discrimination, spatial cueing, and dot-probe tasks. The results showed that pictures rated as strongly uncanny delayed speeded response in the discrimination of the direction of the fish. In the cueing experiment, where a fish served as a task-irrelevant and unpredictable cue for a peripheral target, we again observed that the detection of a target was slowed when the cue was an uncanny fish. Conversely, the dot-probe task suggested that uncanny fish, unlike threatening stimulus, did not capture visual spatial attention. These results suggested that stimulus uncanniness resulted in the delayed response, and importantly this modulation was not mediated by the feelings of threat.

  11. Optimal stimulus shapes for neuronal excitation.

    Directory of Open Access Journals (Sweden)

    Daniel B Forger

    2011-07-01

    Full Text Available An important problem in neuronal computation is to discern how features of stimuli control the timing of action potentials. One aspect of this problem is to determine how an action potential, or spike, can be elicited with the least energy cost, e.g., a minimal amount of applied current. Here we show in the Hodgkin & Huxley model of the action potential and in experiments on squid giant axons that: 1 spike generation in a neuron can be highly discriminatory for stimulus shape and 2 the optimal stimulus shape is dependent upon inputs to the neuron. We show how polarity and time course of post-synaptic currents determine which of these optimal stimulus shapes best excites the neuron. These results are obtained mathematically using the calculus of variations and experimentally using a stochastic search methodology. Our findings reveal a surprising complexity of computation at the single cell level that may be relevant for understanding optimization of signaling in neurons and neuronal networks.

  12. Development of six PROMIS pediatrics proxy-report item banks

    Directory of Open Access Journals (Sweden)

    Irwin Debra E

    2012-02-01

    Full Text Available Abstract Background Pediatric self-report should be considered the standard for measuring patient reported outcomes (PRO among children. However, circumstances exist when the child is too young, cognitively impaired, or too ill to complete a PRO instrument and a proxy-report is needed. This paper describes the development process including the proxy cognitive interviews and large-field-test survey methods and sample characteristics employed to produce item parameters for the Patient Reported Outcomes Measurement Information System (PROMIS pediatric proxy-report item banks. Methods The PROMIS pediatric self-report items were converted into proxy-report items before undergoing cognitive interviews. These items covered six domains (physical function, emotional distress, social peer relationships, fatigue, pain interference, and asthma impact. Caregivers (n = 25 of children ages of 5 and 17 years provided qualitative feedback on proxy-report items to assess any major issues with these items. From May 2008 to March 2009, the large-scale survey enrolled children ages 8-17 years to complete the self-report version and caregivers to complete the proxy-report version of the survey (n = 1548 dyads. Caregivers of children ages 5 to 7 years completed the proxy report survey (n = 432. In addition, caregivers completed other proxy instruments, PedsQL™ 4.0 Generic Core Scales Parent Proxy-Report version, PedsQL™ Asthma Module Parent Proxy-Report version, and KIDSCREEN Parent-Proxy-52. Results Item content was well understood by proxies and did not require item revisions but some proxies clearly noted that determining an answer on behalf of their child was difficult for some items. Dyads and caregivers of children ages 5-17 years old were enrolled in the large-scale testing. The majority were female (85%, married (70%, Caucasian (64% and had at least a high school education (94%. Approximately 50% had children with a chronic health condition, primarily

  13. A new estimate of detrital redox-sensitive metal concentrations and variability in fluxes to marine sediments

    Science.gov (United States)

    Cole, Devon B.; Zhang, Shuang; Planavsky, Noah J.

    2017-10-01

    The enrichment and depletion of redox sensitive trace metals in marine sediments have been used extensively as paleoredox proxies. The trace metals in shale are comprised of both detrital (transported or particulate) and authigenic (precipitated, redox-driven) constituents, potentially complicating the use of this suite of proxies. Untangling the influence of these components is vital for the interpretation of enrichments, depletions, and isotopic signals of iron (Fe), chromium (Cr), uranium (U), and vanadium (V) observed in the rock record. Traditionally, a single crustal average is used as a cutoff for detrital input, and concentrations above or below this value are interpreted as redox derived authigenic enrichment or depletion, while authigenic isotopic signals are frequently corrected for an assumed detrital contribution. Building from an extensive study of soils across the continental United States - which upon transport will become marine sediments - and their elemental concentrations, we find large deviations from accepted crustal averages in redox-sensitive metals (Fe, Cr, U, V) compared to typical detrital tracers (Al, Ti, Sc, Th) and provide new estimates for detrital contributions to the ocean. The variability in these elemental ratios is present over large areas, comparable to the catchment-size of major rivers around the globe. This heterogeneity in detrital flux highlights the need for a reevaluation of how the detrital contribution is assessed in trace metal studies, and the use of confidence intervals rather than single average values, especially in local studies or in the case of small authigenic enrichments.

  14. Proxy-produced ethnographic work: what are the problems, issues, and dilemmas arising from proxy ethnography?

    DEFF Research Database (Denmark)

    Martinussen, Marie Louise; Højbjerg, Karin; Tamborg, Andreas Lindenskov

    2018-01-01

    and positions arising from such a setup between the teacher/researcher and the proxy ethnographer/student are found to have implications for the ethnographies produced. This article’s main focus is to show how these relations and positions have not distorted the ethnographic work and the ethnographies but......This article addresses the implications of research-student cooperation in the production of empirical material. For the student to replace the experienced researcher and work under the researcher’s supervision, we call such work proxy-produced ethnographic work. The specific relations...... the research process. These ethnographic distortions will be generated and described within a framework drawn primarily on the work of sociologist Pierre Bourdieu....

  15. Predicting Attraction to the Novel Stimulus Person: Affect and Concern.

    Science.gov (United States)

    Kelley, Kathryn

    1982-01-01

    Predicted interpersonal attraction to the novel stimulus by assessing the affective properties of stimulus descriptions. One group responded to characterizations on scales of concern. In another group, positive feelings and high concern about the stimulus led to greatest attraction. Results illustrate the benefits of prediction of the liking…

  16. Thallium Isotopes Tracking Mn-Oxide Burial - A Proxy for Deoxygenation During Oceanic Anoxic Event 2

    Science.gov (United States)

    Ostrander, C.; Owens, J. D.; Nielsen, S.

    2015-12-01

    Thallium (Tl) is proving to be a useful paleoredox proxy given that the Tl isotope composition of seawater is highly dependent on the magnitude of manganese (Mn) oxide burial in the ocean. In turn, Mn oxides require oxygen at the sediment-water interface to precipitate, linking the Tl isotope cycle to ocean oxygenation. Currently, the marine residence time of Tl is ~20kyrs and the Tl isotope composition of seawater is invariant, which suggests Tl isotopes could be a global tracer of marine Mn-oxide burial. Importantly, recent research suggests sediments deposited under a euxinic water column faithfully record the Tl isotope value of the overlying oxic water column (e.g. Black Sea and Cariaco Basin). Therefore, analysis of organic-rich black shales may prove useful in evaluating the seawater Tl isotope composition of past oceans and, hence, large-scale burial of Mn-oxides and the extent of bottom water ocean oxygenation. A logical test for this proxy is during the well-studied Cenomanian-Turonian boundary event termed Oceanic Anoxic Event 2 (OAE-2) at ~94 Ma. It is known that the global extent of anoxia and euxinia increased during this event, however, to what extent global bottom water deoxygenation occured is unconstrained. If deep water deoxygenation occurred, it would be hypothesized that Mn-oxide precipitation would decrease, resulting in a positive Tl isotope excursion during OAE-2. We have analyzed the Tl isotope composition of organic-rich black shales from Site 1258 of the Ocean Drilling Program (ODP) spanning the period before, during, and after OAE-2. Based on Fe redox proxies, the entire section is euxinic and thus no Mn-oxides are present (i.e. no local redox changes). Before the event, Tl isotope compositions are similar or slightly heavier than modern seawater values. Just prior to the onset of OAE-2, a positive shift occurs and is maintained until recovery, slightly before the termination of the event. The shift to heavier values and subsequent

  17. Redox-independent chromium isotope fractionation induced by ligand-promoted dissolution.

    Science.gov (United States)

    Saad, Emily M; Wang, Xiangli; Planavsky, Noah J; Reinhard, Christopher T; Tang, Yuanzhi

    2017-11-17

    The chromium (Cr) isotope system has emerged as a potential proxy for tracing the Earth's atmospheric evolution based on a redox-dependent framework for Cr mobilization and isotope fractionation. Although studies have demonstrated that redox-independent pathways can also mobilize Cr, no quantitative constraints exist on the associated isotope fractionations. Here we survey the effects of common environmental ligands on the dissolution of Cr(III)-(oxy)hydroxide solids and associated Cr isotope fractionation. For a variety of organic acids and siderophores, δ(53)Cr values of dissolved Cr(III) are -0.27 to 1.23‰, within the range of previously observed Cr isotope signatures in rock records linked to Cr redox cycling. Thus, ligand-promoted dissolution of Cr-containing solids, a redox-independent process, must be taken into account when using sedimentary Cr isotope signatures to diagnose atmospheric oxygen levels. This work provides a step towards establishing a more robust framework for using Cr isotopes to track the evolution of the Earth's atmosphere.

  18. Engineering redox balance through cofactor systems.

    Science.gov (United States)

    Chen, Xiulai; Li, Shubo; Liu, Liming

    2014-06-01

    Redox balance plays an important role in the production of enzymes, pharmaceuticals, and chemicals. To meet the demands of industrial production, it is desirable that microbes maintain a maximal carbon flux towards target metabolites with no fluctuations in redox. This requires functional cofactor systems that support dynamic homeostasis between different redox states or functional stability in a given redox state. Redox balance can be achieved by improving the self-balance of a cofactor system, regulating the substrate balance of a cofactor system, and engineering the synthetic balance of a cofactor system. This review summarizes how cofactor systems can be manipulated to improve redox balance in microbes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Attacks on One Designated Verifier Proxy Signature Scheme

    Directory of Open Access Journals (Sweden)

    Baoyuan Kang

    2012-01-01

    Full Text Available In a designated verifier proxy signature scheme, there are three participants, namely, the original signer, the proxy signer, and the designated verifier. The original signer delegates his or her signing right to the proxy signer, then the proxy signer can generate valid signature on behalf of the original signer. But only the designated verifier can verify the proxy signature. Several designated verifier proxy signature schemes have been proposed. However, most of them were proven secure in the random oracle model, which has received a lot of criticism since the security proofs in the random oracle model are not sound with respect to the standard model. Recently, by employing Water's hashing technique, Yu et al. proposed a new construction of designated verifier proxy signature. They claimed that the new construction is the first designated verifier proxy signature, whose security does not rely on the random oracles. But, in this paper, we will show some attacks on Yu et al.'s scheme. So, their scheme is not secure.

  20. Factitious Disorder by Proxy in Educational Settings: A Review

    Science.gov (United States)

    Frye, Ellen M.; Feldman, Marc D.

    2012-01-01

    Factitious disorder by proxy (FDP), historically known as Munchausen syndrome by proxy, is a diagnosis applied to parents and other caregivers who intentionally feign, exaggerate, and/or induce illness or injury in a child to get attention from health professionals and others. A review of the recent literature and our experience as consultants…

  1. Applications of redox polymers in biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Boguslavsky, L. (Moltech Corporation, Stony Brook, NY (United States)); Hale, P.D. (Moltech Corporation, Stony Brook, NY (United States)); Geng Lin (Moltech Corporation, Stony Brook, NY (United States)); Skotheim, T.A. (Moltech Corporation, Stony Brook, NY (United States)); Lee Hongsui (Dept. of Applied Science, Brookhaven National Lab., Upton, NY (United States))

    1993-03-01

    Polymers containing covalently attached redox molecules can be highly effective electron transfer mediators for flavin adenine dinucleotide redox centers of many oxidases. Highly flexible siloxane and ethylene oxide polymers containing covalently attached ferrocene molecules are shown to be capable of mediating electron transfer between enzymes and an electrode. The construction and response of bienzyme cholesterol biosensor, acetylcholine and glucose biosensor are described and discussed. Our data showed that the flexibility, hydrophilicity of the polymer, the density of redox centers in the polymer matrices and the self-exchange reaction rate of the redox molecules control the efficiency of the electron transfer mediation. (orig.)

  2. Zinc and the modulation of redox homeostasis

    Science.gov (United States)

    Oteiza, Patricia I.

    2012-01-01

    Zinc, a redox inactive metal, has been long viewed as a component of the antioxidant network, and growing evidence points to its involvement in redox-regulated signaling. These actions are exerted through several mechanisms based on the unique chemical and functional properties of zinc. Overall, zinc contributes to maintain the cell redox balance through different mechanisms including: i) the regulation of oxidant production and metal-induced oxidative damage; ii) the dynamic association of zinc with sulfur in protein cysteine clusters, from which the metal can be released by nitric oxide, peroxides, oxidized glutathione and other thiol oxidant species; iii) zinc-mediated induction of the zinc-binding protein metallothionein, which releases the metal under oxidative conditions and act per se scavenging oxidants; iv) the involvement of zinc in the regulation of glutathione metabolism and of the overall protein thiol redox status; and v) a direct or indirect regulation of redox signaling. Findings of oxidative stress, altered redox signaling, and associated cell/tissue disfunction in cell and animal models of zinc deficiency, stress the relevant role of zinc in the preservation of cell redox homeostasis. However, while the participation of zinc in antioxidant protection, redox sensing, and redox-regulated signaling is accepted, the involved molecules, targets and mechanisms are still partially known and the subject of active research. PMID:22960578

  3. Regulatory redox state in tree seeds

    Directory of Open Access Journals (Sweden)

    Ewelina Ratajczak

    2017-12-01

    Full Text Available Peroxiredoxins (Prx are important regulators of the redox status of tree seeds during maturation and long-term storage. Thioredoxins (Trx are redox transmitters and thereby regulate Prx activity. Current research is focused on the association of Trx with Prx in tree seeds differing in the tolerance to desiccation. The results will allow for better understanding the regulation of the redox status in orthodox, recalcitrant, and intermediate seeds. The findings will also elucidate the role of the redox status during the loss of viability of sensitive seeds during drying and long-term storage.

  4. Perbandingan proxy pada linux dan windows untuk mempercepat browsing website

    Directory of Open Access Journals (Sweden)

    Dafwen Toresa

    2017-05-01

    Full Text Available AbstrakPada saat ini sangat banyak organisasi, baik pendidikan, pemerintahan,  maupun perusahaan swasta berusaha membatasi akses para pengguna ke internet dengan alasan bandwidth yang dimiliki mulai terasa lambat ketika para penggunanya mulai banyak yang melakukan browsing ke internet. Mempercepat akses browsing menjadi perhatian utama dengan memanfaatkan teknologi Proxy server. Penggunaan proxy server perlu mempertimbangkan sistem operasi pada server dan tool yang digunakan belum diketahui performansi terbaiknya pada sistem operasi apa.  Untuk itu dirasa perlu untuk menganalisis performan Proxy server pada sistem operasi berbeda yaitu Sistem Operasi Linux dengan tools Squid  dan Sistem Operasi Windows dengan tool Winroute. Kajian ini dilakukan untuk mengetahui perbandingan kecepatan browsing dari komputer pengguna (client. Browser yang digunakan di komputer pengguna adalah Mozilla Firefox. Penelitian ini menggunakan 2 komputer klien dengan pengujian masing-masingnya 5 kali pengujian pengaksesan/browsing web yang dituju melalui proxy server. Dari hasil pengujian yang dilakukan, diperoleh kesimpulan bahwa penerapan proxy server di sistem operasi linux dengan tools squid lebih cepat browsing dari klien menggunakan web browser yang sama dan komputer klien yang berbeda dari pada proxy server sistem operasi windows dengan tools winroute.  Kata kunci: Proxy, Bandwidth, Browsing, Squid, Winroute AbstractAt this time very many organizations, both education, government, and private companies try to limit the access of users to the internet on the grounds that the bandwidth owned began to feel slow when the users began to do a lot of browsing to the internet. Speed up browsing access is a major concern by utilizing Proxy server technology. The use of proxy servers need to consider the operating system on the server and the tool used is not yet known the best performance on what operating system. For that it is necessary to analyze Performance Proxy

  5. Acute hyperkalemia and failure of pacemaker stimulus.

    Science.gov (United States)

    N'Guetta, Roland; Mansencal, Nicolas; Digne, Franck; Dubourg, Olivier

    2011-07-01

    Acute hyperkalemia may induce well-known serious cardiac arrhythmia. However, ventricular aberration including concealed conduction may also occur. We report the case of a 35-year-old woman who had a previous history of late-operated ventricular septal defect communication and DDD pacemaker was admitted for dyspnea. During hospitalization, an acute hyperkalemia induced sinoatrial block despite correct pacemaker programming. Sodium bicarbonate allowed to restore sinus rhythm. Our report highlights that acute hyperkalemia may increase thresholds of pacemaker stimulus and physicians should be aware that complete block of conduction may occur despite correct pacemaker programming. Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.

  6. Proxy SDN Controller for Wireless Networks

    Directory of Open Access Journals (Sweden)

    Won-Suk Kim

    2016-01-01

    Full Text Available Management of wireless networks as well as wired networks by using software-defined networking (SDN has been highlighted continually. However, control features of a wireless network differ from those of a wired network in several aspects. In this study, we identify the various inefficient points when controlling and managing wireless networks by using SDN and propose SDN-based control architecture called Proxcon to resolve these problems. Proxcon introduces the concept of a proxy SDN controller (PSC for the wireless network control, and the PSC entrusted with the role of a main controller performs control operations and provides the latest network state for a network administrator. To address the control inefficiency, Proxcon supports offloaded SDN operations for controlling wireless networks by utilizing the PSC, such as local control by each PSC, hybrid control utilizing the PSC and the main controller, and locally cooperative control utilizing the PSCs. The proposed architecture and the newly supported control operations can enhance scalability and response time when the logically centralized control plane responds to the various wireless network events. Through actual experiments, we verified that the proposed architecture could address the various control issues such as scalability, response time, and control overhead.

  7. Lithium in Brachiopods - proxy for seawater evolution?

    Science.gov (United States)

    Gaspers, Natalie; Magna, Tomas; Tomasovych, Adam; Henkel, Daniela

    2017-04-01

    Marine biogenic carbonates have the potential to serve as a proxy for evolution of seawater chemistry. In order to compile a record of the past and recent δ7Li in the oceans, foraminifera shells, scleractinian corals and belemnites have been used. However, only a foraminifera-based record appears to more accurately reflect the Li isotope composition of ocean water. At present, this record is available for the Cenozoic with implications for major events during this period of time, including K/T event [1]. A record for the entire Phanerozoic has not yet been obtained. In order to extend this record to the more distant past, Li elemental/isotope systematics of brachiopods were investigated because these marine animals were already present in Early Cambrian oceans and because they are less sensitive to diagenesis-induced modifications due to their shell mineralogy (low-Mg calcite). The preliminary data indicates a species-, temperature- and salinity-independent behavior of Li isotopes in brachiopod shells. Also, no vital effects have been observed for different shell parts. The consistent offset of -4‰ relative to modern seawater is in accordance with experimental data [2]. Further data are now being collected for Cenozoic specimens to more rigorously test brachiopods as possible archives of past seawater in comparison to the existing foraminiferal records. [1] Misra & Froelich (2012) Science 335, 818-823 [2] Marriott et al. (2004) Chem Geol 212, 5-15

  8. Deciphering dynamical proxy responses from lake sediments

    Science.gov (United States)

    Ramisch, Arne; Tjallingii, Rik; Hartmann, Kai; Brauer, Achim; Diekmann, Bernhard; Haberzettl, Torsten; Kasper, Thomas; Ahlborn, Marieke

    2017-04-01

    Lakes form a reliable archive of paleoenvironmental change in the terrestrial realm. Non-destructive XRF scans provide high-resolution records of element concentrations that are commonly related to past environmental change. However, XRF records of lake sediments enclose paleoenvironmental information that originates from multiple lake external and internal forcing. The variety of environmental forcing factors can complicate a direct identification of single mechanisms like climatic change from XRF or other proxy records. Here we present XRF records from several Asian lake archives, which indicate asynchronous variations of similar geochemical records since the late glacial/early Holocene. All XRF time series are characterized by damped harmonic oscillations of relative element concentrations through time. The asynchronous variations can be expressed by the frequency and the rate of damping of theses oscillations that differ between the lakes. We argue that the oscillatory behavior is a result of a feedback between the physical removal and dissolution of mineral phases in catchment soils and their subsequent enrichment and deposition within the lake. We present a numerical model, which accurately simulates major Holocene variations in the element concentration of lake records and discuss implications for the reconstruction of environmental signals from lake sediments.

  9. Multisensory temporal integration: task and stimulus dependencies.

    Science.gov (United States)

    Stevenson, Ryan A; Wallace, Mark T

    2013-06-01

    The ability of human sensory systems to integrate information across the different modalities provides a wide range of behavioral and perceptual benefits. This integration process is dependent upon the temporal relationship of the different sensory signals, with stimuli occurring close together in time typically resulting in the largest behavior changes. The range of temporal intervals over which such benefits are seen is typically referred to as the temporal binding window (TBW). Given the importance of temporal factors in multisensory integration under both normal and atypical circumstances such as autism and dyslexia, the TBW has been measured with a variety of experimental protocols that differ according to criterion, task, and stimulus type, making comparisons across experiments difficult. In the current study, we attempt to elucidate the role that these various factors play in the measurement of this important construct. The results show a strong effect of stimulus type, with the TBW assessed with speech stimuli being both larger and more symmetrical than that seen using simple and complex non-speech stimuli. These effects are robust across task and statistical criteria and are highly consistent within individuals, suggesting substantial overlap in the neural and cognitive operations that govern multisensory temporal processes.

  10. Hospital Clowning as Play Stimulus in Healthcare

    Directory of Open Access Journals (Sweden)

    Laura Anes

    2014-10-01

    Full Text Available A serious illness, a chronic medical condition or a hospital bed should not deny any child her/his basic right to play, a right essential for children’s development and general wellbeing. In fact, it is in these frightening and anxious moments that play and the stimulus that it provides can help the most. This article will focus on the impacts and benefits of professional hospital clowning for the wellbeing and recovery process of ill and hospitalized children. Our experience has shown that through interactive play and humor, “clowndoctors” can create an enabling and supportive environment that facilitates children’s adaptation to the hospital setting and improves their acceptance of medical procedures and staff. While moving from bedside to bedside, RED NOSES clowndoctors encourage children’s active participation and support their natural instinct to play, fully including them in the interaction, if the children wish to do so. Therefore, clowndoctor performances offer ill children much needed stimulus, self-confidence and courage, elements fundamental to reducing their vulnerability. In this piece, a special emphasis will be put on the various approaches used by RED NOSES clowndoctors to bond and reach out to children suffering from different medical conditions.

  11. Characterization of redox conditions in pollution plumes

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Bjerg, Poul Løgstrup; Banwart, Steven A.

    2000-01-01

    Evalution of redox conditions in groundwater pollution plumes is often a prerequisite for understanding the behviour of the pollutants in the plume and for selecting remediation approaches. Measuring of redox conditions in pollution plumes is, however, a fairly recent issue and yet relative few...

  12. Characterization of redox proteins using electrochemical methods

    NARCIS (Netherlands)

    Verhagen, M.

    1995-01-01

    The use of electrochemical techniques in combination with proteins started approximately a decade ago and has since then developed into a powerfull technique for the study of small redox proteins. In addition to the determination of redox potentials, electrochemistry can be used to obtain

  13. Secure Mobile Agent from Leakage-Resilient Proxy Signatures

    Directory of Open Access Journals (Sweden)

    Fei Tang

    2015-01-01

    Full Text Available A mobile agent can sign a message in a remote server on behalf of a customer without exposing its secret key; it can be used not only to search for special products or services, but also to make a contract with a remote server. Hence a mobile agent system can be used for electronic commerce as an important key technology. In order to realize such a system, Lee et al. showed that a secure mobile agent can be constructed using proxy signatures. Intuitively, a proxy signature permits an entity (delegator to delegate its signing right to another entity (proxy to sign some specified messages on behalf of the delegator. However, the proxy signatures are often used in scenarios where the signing is done in an insecure environment, for example, the remote server of a mobile agent system. In such setting, an adversary could launch side-channel attacks to exploit some leakage information about the proxy key or even other secret states. The proxy signatures which are secure in the traditional security models obviously cannot provide such security. Based on this consideration, in this paper, we design a leakage-resilient proxy signature scheme for the secure mobile agent systems.

  14. Proxies and consent discussions for dementia research.

    Science.gov (United States)

    Sugarman, Jeremy; Roter, Debra; Cain, Carole; Wallace, Roberta; Schmechel, Don; Welsh-Bohmer, Kathleen A

    2007-04-01

    To better understand the nature of informed consent encounters for research involving patients with dementia that requires proxy consent. Audiotaping of informed-consent encounters for a study of genetic markers for sporadic Alzheimer's disease. Outpatients at an Alzheimer's disease research center. Patients with dementia and their companions. Audiotapes were analyzed to characterize communication style and coverage of the standard elements of informed consent and, using the Roter Interaction Analysis System, to capture the dynamics of three-way interaction between the patient, their companion, and the physician investigator. Of 26 informed consent encounters, all involved a patient, a companion, and a physician. Patients had a mean Mini-Mental State Examination (MMSE) score of 21.8. For patients, 49% of their interactions involved agreement and approval (positive statements), 16% psychosocial information, 7% biomedical information, 7% asking questions, and 7% expressing emotion. Companion interactions involved 37% positive statements and 19% biomedical information. Physician interactions involved emotional expressiveness (30%) and positive statements (19%). Discussion length was positively related to MMSE score (Spearman rho=0.45; Pinformed consent was fairly comprehensive and had no relationship to patients' MMSE scores. These data should inform policies regarding the ethically appropriate ways of conducting research with cognitively impaired adults. For example, patients in this study were more silent than their companions and the physician, but when patients spoke, they primarily agreed with what was said. Although this might first seem to signal assent, such an interpretation should be made with caution for persons with dementia. In addition, previous work on informed consent has focused on its cognitive aspects, but these data reveal that the emotional and social dimensions warrant attention.

  15. Application and Network-Cognizant Proxies - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Antonio Ortega; Daniel C. Lee

    2003-03-24

    OAK B264 Application and Network-Cognizant Proxies - Final Report. Current networks show increasing heterogeneity both in terms of their bandwidths/delays and the applications they are required to support. This is a trend that is likely to intensify in the future, as real-time services, such as video, become more widely available and networking access over wireless links becomes more widespread. For this reason they propose that application-specific proxies, intermediate network nodes that broker the interactions between server and client, will become an increasingly important network element. These proxies will allow adaptation to changes in network characteristics without requiring a direct intervention of either server or client. Moreover, it will be possible to locate these proxies strategically at those points where a mismatch occurs between subdomains (for example, a proxy could be placed so as to act as a bridge between a reliable network domain and an unreliable one). This design philosophy favors scalability in the sense that the basic network infrastructure can remain unchanged while new functionality can be added to proxies, as required by the applications. While proxies can perform numerous generic functions, such as caching or security, they concentrate here on media-specific, and in particular video-specific, tasks. The goal of this project was to demonstrate that application- and network-specific knowledge at a proxy can improve overall performance especially under changing network conditions. They summarize below the work performed to address these issues. Particular effort was spent in studying caching techniques and on video classification to enable DiffServ delivery. other work included analysis of traffic characteristics, optimized media scheduling, coding techniques based on multiple description coding, and use of proxies to reduce computation costs. This work covered much of what was originally proposed but with a necessarily reduced scope.

  16. Optimizing TCP Performance over UMTS with Split TCP Proxy

    DEFF Research Database (Denmark)

    Hu, Liang; Dittmann, Lars

    2009-01-01

    Abstract: The TCP performance over UMTS network is challenged by the large delay bandwidth product. Large delay bandwidth product is mainly caused by the latency from the link layer ARQ retransmissions and diversity technique at physical layer which are used to cope with radio transmission errors...... scenario (e.g.64 kbps). Besides, the split TCP proxy brings more performance gain for downloading large files than downloading small ones. To the end, for the configuration of the split proxy, an aggressive initial TCP congestion window size (e.g. 10 MSS) at proxy is particularly useful for radio links...

  17. Cryptanalytic Performance Appraisal of Improved CCH2 Proxy Multisignature Scheme

    Directory of Open Access Journals (Sweden)

    Raman Kumar

    2014-01-01

    Full Text Available Many of the signature schemes are proposed in which the t out of n threshold schemes are deployed, but they still lack the property of security. In this paper, we have discussed implementation of improved CCH1 and improved CCH2 proxy multisignature scheme based on elliptic curve cryptosystem. We have represented time complexity, space complexity, and computational overhead of improved CCH1 and CCH2 proxy multisignature schemes. We have presented cryptanalysis of improved CCH2 proxy multisignature scheme and showed that improved CCH2 scheme suffered from various attacks, that is, forgery attack and framing attack.

  18. Web proxy cache replacement strategies simulation, implementation, and performance evaluation

    CERN Document Server

    ElAarag, Hala; Cobb, Jake

    2013-01-01

    This work presents a study of cache replacement strategies designed for static web content. Proxy servers can improve performance by caching static web content such as cascading style sheets, java script source files, and large files such as images. This topic is particularly important in wireless ad hoc networks, in which mobile devices act as proxy servers for a group of other mobile devices. Opening chapters present an introduction to web requests and the characteristics of web objects, web proxy servers and Squid, and artificial neural networks. This is followed by a comprehensive review o

  19. Redox activity of naphthalene secondary organic aerosol

    Science.gov (United States)

    McWhinney, R. D.; Zhou, S.; Abbatt, J. P. D.

    2013-04-01

    Chamber secondary organic aerosol (SOA) from low-NOx photooxidation of naphthalene by hydroxyl radical was examined with respect to its redox cycling behaviour using the dithiothreitol (DTT) assay. Naphthalene SOA was highly redox active, consuming DTT at an average rate of 118 ± 14 pmol per minute per μg of SOA material. Measured particle-phase masses of the major previously identified redox active products, 1,2- and 1,4-naphthoquinone, accounted for only 21 ± 3% of the observed redox cycling activity. The redox-active 5-hydroxy-1,4-naphthoquinone was identified as a new minor product of naphthalene oxidation, and including this species in redox activity predictions increased the predicted DTT reactivity to 30 ± 5% of observations. Similar attempts to predict redox behaviour of oxidised two-stroke engine exhaust particles by measuring 1,2-naphthoquinone, 1,4-naphthoquinone and 9,10-phenanthrenequinone predicted DTT decay rates only 4.9 ± 2.5% of those observed. Together, these results suggest that there are substantial unidentified redox-active SOA constituents beyond the small quinones that may be important toxic components of these particles. A gas-to-SOA particle partitioning coefficient was calculated to be (7.0 ± 2.5) × 10-4 m3 μg-1 for 1,4-naphthoquinone at 25 °C. This value suggests that under typical warm conditions, 1,4-naphthoquinone is unlikely to contribute strongly to redox behaviour of ambient particles, although further work is needed to determine the potential impact under conditions such as low temperatures where partitioning to the particle is more favourable. As well, higher order oxidation products that likely account for a substantial fraction of the redox cycling capability of the naphthalene SOA are likely to partition much more strongly to the particle phase.

  20. Engineered Proteins: Redox Properties and Their Applications

    Science.gov (United States)

    Prabhulkar, Shradha; Tian, Hui; Wang, Xiaotang; Zhu, Jun-Jie

    2012-01-01

    Abstract Oxidoreductases and metalloproteins, representing more than one third of all known proteins, serve as significant catalysts for numerous biological processes that involve electron transfers such as photosynthesis, respiration, metabolism, and molecular signaling. The functional properties of the oxidoreductases/metalloproteins are determined by the nature of their redox centers. Protein engineering is a powerful approach that is used to incorporate biological and abiological redox cofactors as well as novel enzymes and redox proteins with predictable structures and desirable functions for important biological and chemical applications. The methods of protein engineering, mainly rational design, directed evolution, protein surface modifications, and domain shuffling, have allowed the creation and study of a number of redox proteins. This review presents a selection of engineered redox proteins achieved through these methods, resulting in a manipulation in redox potentials, an increase in electron-transfer efficiency, and an expansion of native proteins by de novo design. Such engineered/modified redox proteins with desired properties have led to a broad spectrum of practical applications, ranging from biosensors, biofuel cells, to pharmaceuticals and hybrid catalysis. Glucose biosensors are one of the most successful products in enzyme electrochemistry, with reconstituted glucose oxidase achieving effective electrical communication with the sensor electrode; direct electron-transfer-type biofuel cells are developed to avoid thermodynamic loss and mediator leakage; and fusion proteins of P450s and redox partners make the biocatalytic generation of drug metabolites possible. In summary, this review includes the properties and applications of the engineered redox proteins as well as their significance and great potential in the exploration of bioelectrochemical sensing devices. Antioxid. Redox Signal. 17, 1796–1822. PMID:22435347

  1. Lorazepam substitutes for the alcohol stimulus in social drinkers.

    Science.gov (United States)

    Jackson, Anne; Stephens, David N; Duka, Theodora

    2003-03-01

    The alcohol discriminative stimulus has been extensively studied in animals and demonstrated to be pharmacologically complex. In contrast, however, the alcohol stimulus has been less frequently studied in humans. The aim of the experiments reported here was to characterise pharmacologically an alcohol discriminative stimulus in social drinkers. Volunteers were first trained to discriminate a dose of 0.2 g/kg alcohol from placebo, using an established method. We then investigated the generalisation response and subjective effects following a range of doses of the gamma-amino-butyric acid (GABA)(A) benzodiazepine-receptor agonist lorazepam (0, 0.5, 1 and 2 mg, PO). Low doses of lorazepam (0.5 and 1 mg) did not cross-generalise with the alcohol stimulus and produced only minimal subjective effects. However, a dose of 2 mg lorazepam substituted (60.8%) for the stimulus ( Palcohol discriminative stimulus.

  2. Munchausen syndrome by proxy presenting as hearing loss.

    Science.gov (United States)

    Ashraf, N; Thevasagayam, M S

    2014-06-01

    To review the diagnosis of Munchausen syndrome by proxy, a factitious disorder, in which symptoms are induced or feigned, usually in a child, by the caregiver. The involved caregiver seeks to gain attention or sympathy and often has a psychological need to maintain the sick role. We highlight the diagnostic difficulties and factors that may help with diagnosis in an otolaryngology setting. We present the case of Munchausen syndrome by proxy presenting with hearing loss in a five-year old boy, who was diagnosed eight years after his initial presentation. A literature review of Munchausen syndrome by proxy cases presenting with ENT symptoms is provided. Munchausen syndrome by proxy is a diagnosis that otolaryngologists should be aware of, particularly where recurrent or persistent illnesses in children, especially those involving otological symptoms, are refractory to the usual treatments.

  3. Munchausen Syndrome by Proxy: Unusual Manifestations and Disturbing Sequelae.

    Science.gov (United States)

    Porter, Gerald E.; And Others

    1994-01-01

    This study documents previously unreported findings in cases of Munchausen Syndrome by Proxy (in which a mother fabricates an illness in her child). In the reported case, esophageal perforation, retrograde intussusception, tooth loss, and bradycardia were found. (Author/DB)

  4. Varieties of Capitalism and Fiscal Stimulus, 2008–2010

    Directory of Open Access Journals (Sweden)

    Toloudis Nicholas

    2015-10-01

    Full Text Available This paper tests the Varieties of Capitalism (VoC framework to explain variation in fiscal stimulus measures across OECD countries in response to the 2008-2010 economic crisis. Following Soskice (2007, I argue that coordinated market economies are less flexible with fiscal policy than liberal market economies. Multivariate analysis across 23 OECD countries demonstrates that VoC is more powerful than three competing theories: fiscal institutions, which hypothesizes more stimulus in countries with less restrictive budgetary rules; debt credibility, which hypothesizes more stimulus in less indebted countries; and political partisanship, which hypothesizes more stimulus in countries governed by the left.

  5. The effects of stimulus symmetry on hierarchical processing in infancy.

    Science.gov (United States)

    Guy, Maggie W; Reynolds, Greg D; Mosteller, Sara M; Dixon, Kate C

    2017-04-01

    The current study investigated the effects of stimulus symmetry on the processing of global and local stimulus properties by 6-month-old short- and long-looking infants through the use of event-related potentials (ERPs). Previous research has shown that individual differences in infant visual attention are related to hierarchical stimulus processing, such that short lookers show a global processing bias, while long lookers demonstrate a local processing bias (Guy, Reynolds, & Zhang, 2013). Additional research has shown that in comparison with asymmetry, symmetry is associated with more efficient stimulus processing and more accurate memory for stimulus configuration (Attneave, 1955; Perkins, 1932). In the current study, we utilized symmetric and asymmetric hierarchical stimuli and predicted that the presence of asymmetry would direct infant attention to the local features of stimuli, leading short lookers to regress to a local processing strategy. Results of the ERP analysis showed that infants familiarized with a symmetric stimulus showed evidence of global processing, while infants familiarized with an asymmetric stimulus did not demonstrate evidence of processing at the global or local level. These findings indicate that short- and long-looking infants, who might otherwise fail to process global stimulus properties due to limited visual scanning, may succeed at global processing when exposed to symmetric stimuli. Furthermore, stimulus symmetry may recruit selective attention toward global properties of visual stimuli, facilitating higher-level cognitive processing in infancy. © 2017 Wiley Periodicals, Inc.

  6. Applicability of a cognitive questionnaire in the elderly and proxy

    Directory of Open Access Journals (Sweden)

    Renata Areza Fegyveres

    Full Text Available Abstract The Informant Questionnaire on Cognitive Decline in the Elderly with the Proxy (IQCODE was developed as a screening tool for cognition alterations. Objectives: 1 To verify the applicability of IQCODE in the elderly with limited schooling, 2 To verify the reliability of the responses supplied by the aged and their proxies. Methods: Individuals of a Community Group were evaluated using the Mini-Mental State Examination (MMSE, IQCODE and Geriatric Depression Scale (GDS. The IQCODE was applied to informants and proxies. Results: We analyzed 44 individuals, aged between 58-82 years (M=66.8, SD=5.97 with mean elderly-schooling level of 3.75, SD=2.82 and 44 proxies aged 44.5 (SD=13.3, with mean schooling level of 8.25 (SD=4.3. The mean GDS was 8.22, SD=4.90 and 13 participants presented a score suggestive of depressive symptoms. The mean elderly IQCODE score was 3.26, SD=0.69 and 3.21, SD=0.65, for proxy responses. There was no statistical difference between these means. On the MMSE, the mean score was 24.20, SD=4.14 and 18 participants presented scores below the cut-off. The IQCODE answers by the elderly in this latter group were more congruent with MMSE than the answers of proxies. Conclusions: The applicability of the IQCODE in a population with little schooling was verified in that the proxy-report was similar to the elderly report. We can affirm that the elderly answers were more accurate than the proxies, as they were closer to MMSE score. The inclusion of a greater number of participants from community-dwelling settings is necessary to confirm the results obtained in this study.

  7. Proxy-rated quality of life in Alzheimer's disease

    DEFF Research Database (Denmark)

    Vogel, Asmus; Bhattacharya, Suvosree; Waldorff, Frans Boch

    2012-01-01

    The study investigated the change in proxy rated quality of life (QoL) of a large cohort of home living patients with Alzheimer's disease (AD) over a period of 36 months.......The study investigated the change in proxy rated quality of life (QoL) of a large cohort of home living patients with Alzheimer's disease (AD) over a period of 36 months....

  8. Organelle redox autonomy during environmental stress.

    Science.gov (United States)

    Bratt, Avishay; Rosenwasser, Shilo; Meyer, Andreas; Fluhr, Robert

    2016-09-01

    Oxidative stress is generated in plants because of inequalities in the rate of reactive oxygen species (ROS) generation and scavenging. The subcellular redox state under various stress conditions was assessed using the redox reporter roGFP2 targeted to chloroplastic, mitochondrial, peroxisomal and cytosolic compartments. In parallel, the vitality of the plant was measured by ion leakage. Our results revealed that during certain physiological stress conditions the changes in roGFP2 oxidation are comparable to application of high concentrations of exogenous H2 O2 . Under each stress, particular organelles were affected. Conditions of extended dark stress, or application of elicitor, impacted chiefly on the status of peroxisomal redox state. In contrast, conditions of drought or high light altered the status of mitochondrial or chloroplast redox state, respectively. Amalgamation of the results from diverse environmental stresses shows cases of organelle autonomy as well as multi-organelle oxidative change. Importantly, organelle-specific oxidation under several stresses proceeded cell death as measured by ion leakage, suggesting early roGFP oxidation as predictive of cell death. The measurement of redox state in multiple compartments enables one to look at redox state connectivity between organelles in relation to oxidative stress as well as assign a redox fingerprint to various types of stress conditions. © 2016 John Wiley & Sons Ltd.

  9. Comment on "Apatite: A new redox proxy for silicic magmas?" [Geochimica et Cosmochimica Acta 132 (2014) 101-119

    Science.gov (United States)

    Marks, Michael A. W.; Scharrer, Manuel; Ladenburger, Sara; Markl, Gregor

    2016-06-01

    Recently Miles et al. (2014) proposed that a negative correlation between oxygen fugacity (expressed as logfO2 and the Mn content of apatite from a range of intermediate to silicic igneous rocks could be used as an oxybarometer (Eq. (1)).

  10. [The P300 based brain-computer interface: effect of stimulus position in a stimulus train].

    Science.gov (United States)

    Ganin, I P; Shishkin, S L; Kochetova, A G; Kaplan, A Ia

    2012-01-01

    The P300 brain-computer interface (BCI) is currently the most efficient BCI. This interface is based on detection of the P300 wave of the brain potentials evoked when a symbol related to the intended input is highlighted. To increase operation speed of the P300 BCI, reduction of the number of stimuli repetitions is needed. This reduction leads to increase of the relative contribution to the input symbol detection from the reaction to the first target stimulus. It is known that the event-related potentials (ERP) to the first stimulus presentations can be different from the ERP to stimuli presented latter. In particular, the amplitude of responses to the first stimulus presentations is often increased, which is beneficial for their recognition by the BCI. However, this effect was not studied within the BCI framework. The current study examined the ERP obtained from healthy participants (n = 14) in the standard P300 BCI paradigm using 10 trials, as well as in the modified P300 BCI with stimuli presented on moving objects in triple-trial (n = 6) and single-trial (n = 6) stimulation modes. Increased ERP amplitude was observed in response to the first target stimuli in both conditions, as well as in the single-trial mode comparing to triple-trial. We discuss the prospects of using the specific features of the ERP to first stimuli and the single-trial ERP for optimizing the high-speed modes in the P300 BCIs.

  11. Classical Conditioning Components of the Orienting Reflex to Words Using Innocuous and Noxious Unconditioned Stimuli Under Different Conditioned Stimulus-Unconditioned Stimulus Intervals

    Science.gov (United States)

    Maltzman, Irving; And Others

    1977-01-01

    Concerns the examination of conditioned stimulus--unconditioned stimulus (CS--UCS) intervals of different lengths. Demonstrates the feasibility of using a forewarned reaction time procedure with an innocuous imperative stimulus for the investigation of classical conditioning. (Editor/RK)

  12. Redox activity of naphthalene secondary organic aerosol

    OpenAIRE

    R. D. McWhinney; S. Zhou; J. P. D. Abbatt

    2013-01-01

    Chamber secondary organic aerosol (SOA) from low-NOx photooxidation of naphthalene by hydroxyl radical was examined with respect to its redox cycling behaviour using the dithiothreitol (DTT) assay. Naphthalene SOA was highly redox active, consuming DTT at an average rate of 118 ± 14 pmol per minute per μg of SOA material. Measured particle-phase masses of the major previously identified redox active products, 1,2- and 1,4-naphthoquinone, accounted for only 21 ± 3% of the obse...

  13. Towards A Modern Calibration Of The 238U/235U Paleoredox Proxy: Apparent Uranium Isotope Fractionation Factor During U(VI)-U(IV) Reduction In The Black Sea

    Science.gov (United States)

    Rolison, J. M.; Stirling, C. H.; Middag, R.; Rijkenberg, M. J. A.; De Baar, H. J. W.

    2015-12-01

    The isotopic compositions of redox-sensitive metals, including uranium (U), in marine sediments have recently emerged as powerful diagnostic tracers of the redox state of the ancient ocean-atmosphere system. Interpretation of sedimentary isotopic information requires a thorough understating of the environmental controls on isotopic fractionation in modern anoxic environments before being applied to the paleo-record. In this study, the relationship between ocean anoxia and the isotopic fractionation of U was investigated in the water column and sediments of the Black Sea. The Black Sea is the world's largest anoxic basin and significant removal of U from the water column and high U accumulation rates in modern underlying sediments have been documented. Removal of U from the water column occurs during the redox transition of soluble U(VI) to relatively insoluble U(IV). The primary results of this study are two-fold. First, significant 238U/235U fractionation was observed in the water column of the Black Sea, suggesting the reduction of U induces 238U/235U fractionation with the preferential removal of 238U from the aqueous phase. Second, the 238U/235U of underlying sediments is related to the water column through the isotope fractionation factor of the reduction reaction but is influenced by mass transport processes. These results provide important constraints on the use of 238U/235U as a proxy of the redox state of ancient oceans.

  14. Changes in microbial communities along redox gradients in polygonized Arctic wet tundra soils

    Energy Technology Data Exchange (ETDEWEB)

    Lipson, David A.; Raab, Theodore K.; Parker , Melanie; Kelley , Scott T.; Brislawn, Colin J.; Jansson, Janet K.

    2015-07-21

    This study investigated how microbial community structure and diversity varied with depth and topography in ice wedge polygons of wet tundra of the Arctic Coastal Plain in northern Alaska, and what soil variables explain these patterns. We observed strong changes in community structure and diversity with depth, and more subtle changes between areas of high and low topography, with the largest differences apparent near the soil surface. These patterns are most strongly correlated with redox gradients (measured using the ratio of reduced Fe to total Fe in acid extracts as a proxy): conditions grew more reducing with depth and were most oxidized in shallow regions of polygon rims. Organic matter and pH also changed with depth and topography, but were less effective predictors of the microbial community structure and relative abundance of specific taxa. Of all other measured variables, lactic acid concentration was the best, in combination with redox, for describing the microbial community. We conclude that redox conditions are the dominant force in shaping microbial communities in this landscape. Oxygen and other electron acceptors allowed for the greatest diversity of microbes: at depth the community was reduced to a simpler core of anaerobes, dominated by fermenters (Bacteroidetes and Firmicutes).

  15. Changes in microbial communities along redox gradients in polygonized Arctic wet tundra soils.

    Science.gov (United States)

    Lipson, David A; Raab, Theodore K; Parker, Melanie; Kelley, Scott T; Brislawn, Colin J; Jansson, Janet

    2015-08-01

    This study investigated how microbial community structure and diversity varied with depth and topography in ice wedge polygons of wet tundra of the Arctic Coastal Plain in northern Alaska and what soil variables explain these patterns. We observed strong changes in community structure and diversity with depth, and more subtle changes between areas of high and low topography, with the largest differences apparent near the soil surface. These patterns are most strongly correlated with redox gradients (measured using the ratio of reduced Fe to total Fe in acid extracts as a proxy): conditions grew more reducing with depth and were most oxidized in shallow regions of polygon rims. Organic matter and pH also changed with depth and topography but were less effective predictors of the microbial community structure and relative abundance of specific taxa. Of all other measured variables, lactic acid concentration was the best, in combination with redox, for describing the microbial community. We conclude that redox conditions are the dominant force in shaping microbial communities in this landscape. Oxygen and other electron acceptors allowed for the greatest diversity of microbes: at depth the community was reduced to a simpler core of anaerobes, dominated by fermenters (Bacteroidetes and Firmicutes). © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  16. Changes in microbial communities along redox gradients in polygonized Arctic wet tundra soils

    Energy Technology Data Exchange (ETDEWEB)

    Lipson, David A.; Raab, Theodore K.; Parker , Melanie; Kelley , Scott T.; Brislawn, Colin J.; Jansson, Janet K.

    2015-08-01

    Summary This study investigated how microbial community structure and diversity varied with depth and topography in ice wedge polygons of wet tundra of the Arctic Coastal Plain in northern Alaska and what soil variables explain these patterns. We observed strong changes in community structure and diversity with depth, and more subtle changes between areas of high and low topography, with the largest differences apparent near the soil surface. These patterns are most strongly correlated with redox gradients (measured using the ratio of reduced Fe to total Fe in acid extracts as a proxy): conditions grew more reducing with depth and were most oxidized in shallow regions of polygon rims. Organic matter and pH also changed with depth and topography but were less effective predictors of the microbial community structure and relative abundance of specific taxa. Of all other measured variables, lactic acid concentration was the best, in combination with redox, for describing the microbial community. We conclude that redox conditions are the dominant force in shaping microbial communities in this landscape. Oxygen and other electron acceptors allowed for the greatest diversity of microbes: at depth the community was reduced to a simpler core of anaerobes,

  17. Emotion stimulus processing in narcolepsy with cataplexy.

    Science.gov (United States)

    Susta, Marek; Nemcova, Veronika; Bizik, Gustav; Sonka, Karel

    2017-02-01

    Reported brain abnormalities in anatomy and function in patients with narcolepsy with cataplexy led to a project based on qualitative electroencephalography examination and analysis in an attempt to find a narcolepsy with cataplexy-specific brain-derived pattern, or a sequence of brain locations involved in processing humorous stimuli. Laughter is the trigger of cataplexy in these patients, and the difference between patients and healthy controls during the laughter should therefore be notable. Twenty-six adult patients (14 male, 12 female) suffering from narcolepsy with cataplexy and 10 healthy controls (five male, five female) were examined. The experiment was performed using a 256-channel electroencephalogram and then processed using specialized software built according to the scientific research team's specifications. The software utilizes electroencephalographic data recorded during elevated emotional states in participants to calculate the sequence of brain areas involved in emotion processing using non-linear and linear algorithms. Results show significant differences in activation (pre-laughter) patterns between the patients with narcolepsy and healthy controls, as well as significant similarities within the patients and the controls. Specifically, gyrus orbitalis, rectus and occipitalis inferior are active in healthy controls, while gyrus paracentralis, cingularis and cuneus are activated solely in the patients in response to humorous audio stimulus. There are qualitative electroencephalographic-based patterns clearly discriminating between patients with narcolepsy and healthy controls during laughter processing. © 2016 European Sleep Research Society.

  18. Transformation of stimulus correlations by the retina.

    Directory of Open Access Journals (Sweden)

    Kristina D Simmons

    Full Text Available Redundancies and correlations in the responses of sensory neurons may seem to waste neural resources, but they can also carry cues about structured stimuli and may help the brain to correct for response errors. To investigate the effect of stimulus structure on redundancy in retina, we measured simultaneous responses from populations of retinal ganglion cells presented with natural and artificial stimuli that varied greatly in correlation structure; these stimuli and recordings are publicly available online. Responding to spatio-temporally structured stimuli such as natural movies, pairs of ganglion cells were modestly more correlated than in response to white noise checkerboards, but they were much less correlated than predicted by a non-adapting functional model of retinal response. Meanwhile, responding to stimuli with purely spatial correlations, pairs of ganglion cells showed increased correlations consistent with a static, non-adapting receptive field and nonlinearity. We found that in response to spatio-temporally correlated stimuli, ganglion cells had faster temporal kernels and tended to have stronger surrounds. These properties of individual cells, along with gain changes that opposed changes in effective contrast at the ganglion cell input, largely explained the pattern of pairwise correlations across stimuli where receptive field measurements were possible.

  19. High energy density redox flow device

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, Yet-Ming; Carter, Craig W.; Ho, Bryan Y.; Duduta, Mihai; Limthongkul, Pimpa

    2017-10-10

    Redox flow devices are described in which at least one of the positive electrode or negative electrode-active materials is a semi-solid or is a condensed ion-storing electroactive material, and in which at least one of the electrode-active materials is transported to and from an assembly at which the electrochemical reaction occurs, producing electrical energy. The electronic conductivity of the semi-solid is increased by the addition of conductive particles to suspensions and/or via the surface modification of the solid in semi-solids (e.g., by coating the solid with a more electron conductive coating material to increase the power of the device). High energy density and high power redox flow devices are disclosed. The redox flow devices described herein can also include one or more inventive design features. In addition, inventive chemistries for use in redox flow devices are also described.

  20. Polyarene mediators for mediated redox flow battery

    Energy Technology Data Exchange (ETDEWEB)

    Delnick, Frank M.; Ingersoll, David; Liang, Chengdu

    2018-01-02

    The fundamental charge storage mechanisms in a number of currently studied high energy redox couples are based on intercalation, conversion, or displacement reactions. With exception to certain metal-air chemistries, most often the active redox materials are stored physically in the electrochemical cell stack thereby lowering the practical gravimetric and volumetric energy density as a tradeoff to achieve reasonable power density. In a general embodiment, a mediated redox flow battery includes a series of secondary organic molecules that form highly reduced anionic radicals as reaction mediator pairs for the reduction and oxidation of primary high capacity redox species ex situ from the electrochemical cell stack. Arenes are reduced to stable anionic radicals that in turn reduce a primary anode to the charged state. The primary anode is then discharged using a second lower potential (more positive) arene. Compatible separators and solvents are also disclosed herein.

  1. A redox-flow electrochromic window.

    Science.gov (United States)

    Jennings, James R; Lim, Wei Yang; Zakeeruddin, Shaik M; Grätzel, Michael; Wang, Qing

    2015-02-04

    A low-cost electrochromic (EC) window based on a redox-flow system that does not require expensive transparent conductive oxide (TCO) substrates is introduced and demonstrated for the first time. An aqueous I3–/I– redox electrolyte is used in place of a TCO to oxidize/reduce a molecular layer of an EC triphenylamine derivative that is anchored to a mesoporous TiO2 scaffold on the inner faces of a double-paned window. The redox electrolyte is electrochemically oxidized/reduced in an external two-compartment cell and circulated through the window cavity using an inexpensive peristaltic pump, resulting in coloration or decoloration of the window due to reaction of the redox solution with the triphenylamine derivative. The absorption characteristics, coloration/decoloration times, and cycling stability of the prototype EC window are evaluated, and prospects for further development are discussed.

  2. Redox Modulations, Antioxidants, and Neuropsychiatric Disorders

    Science.gov (United States)

    Fraunberger, Erik A.; Laliberté, Victoria L. M.; Duong, Angela; Andreazza, Ana C.

    2016-01-01

    Although antioxidants, redox modulations, and neuropsychiatric disorders have been widely studied for many years, the field would benefit from an integrative and corroborative review. Our primary objective is to delineate the biological significance of compounds that modulate our redox status (i.e., reactive species and antioxidants) as well as outline their current role in brain health and the impact of redox modulations on the severity of illnesses. Therefore, this review will not enter into the debate regarding the perceived medical legitimacy of antioxidants but rather seek to clarify their abilities and limitations. With this in mind, antioxidants may be interpreted as natural products with significant pharmacological actions in the body. A renewed understanding of these often overlooked compounds will allow us to critically appraise the current literature and provide an informed, novel perspective on an important healthcare issue. In this review, we will introduce the complex topics of redox modulations and their role in the development of select neuropsychiatric disorders. PMID:26640614

  3. P3a from a passive visual stimulus task.

    Science.gov (United States)

    Jeon, Y W; Polich, J

    2001-12-01

    Visual event-related brain potentials (ERPs) were elicited using a 3-stimulus oddball paradigm to assess the P3a with passive stimulus processing. Young adults (n=12) were presented with a series of visual stimuli consisting of a solid circle standard stimulus (P=0.76) that was difficult to discriminate from a larger target circle (P=0.12), with a large square distractor stimulus (P=0.12) presented randomly in the series. Subjects were instructed in the passive condition to simply look at the stimuli and in the active condition to press a mouse key only to the target stimulus. ERPs were recorded from 15 scalp electrodes, with the amplitude and latency of the P300 from the distractor and target stimuli assessed. The P3a from the distractor stimulus was similar in amplitude, scalp topography, and peak latency across the passive and active task conditions. The P3b from the target stimulus demonstrated much smaller amplitude, highly altered scalp topography, and longer latency for the passive compared to active task conditions. The P3a can be obtained with visual stimuli in the 3-stimulus paradigm under passive viewing conditions. Theoretical implications and clinical applications are discussed.

  4. A Computer Tutorial on the Principles of Stimulus Generalization.

    Science.gov (United States)

    Graham, Robert B.

    1998-01-01

    Describes a computer tutorial that teaches the fundamentals of stimulus generalization in operant learning. Concepts covered include reinforcement, discrimination learning, stimulus continua, generalization, generalization gradients, and peak shift. The tutorial also reviews applications in human and animal situations. The content is appropriate…

  5. Redox-Dependent Conformational Switching of Diphenylacetylenes

    Directory of Open Access Journals (Sweden)

    Ian M. Jones

    2014-07-01

    Full Text Available Herein we describe the design and synthesis of a redox-dependent single-molecule switch. Appending a ferrocene unit to a diphenylacetylene scaffold gives a redox-sensitive handle, which undergoes reversible one-electron oxidation, as demonstrated by cyclic voltammetry analysis. 1H-NMR spectroscopy of the partially oxidized switch and control compounds suggests that oxidation to the ferrocenium cation induces a change in hydrogen bonding interactions that results in a conformational switch.

  6. Stimulus conflict predicts conflict adaptation in a numerical flanker task.

    Science.gov (United States)

    Notebaert, Wim; Verguts, Tom

    2006-12-01

    Conflict monitoring theory states that response conflict triggers conflict adaptation, resulting in reduced congruency effects after response-incongruent trials (Botvinick, Braver, Barch, Carter, & Cohen, 2001). Verbruggen, Notebaert, Liefooghe, and Vandierendonck (2006) observed conflict adaptation after stimulus-incongruent trials without any response conflict. In this study, we further explorethe hypothesis that stimulus conflict is an important trigger for conflict adaptation. We propose a measure for stimulus conflict that adequately explains the data of Verbruggen et al. and new data from a numerical flanker task. We conclude that stimulus conflict and response conflict have dissociable effects on behavior. Whereas response conflict is a good predictor of response times, stimulus conflict is a better predictor of the adaptation effect.

  7. Nuclear thiol redox systems in plants.

    Science.gov (United States)

    Delorme-Hinoux, Valérie; Bangash, Sajid A K; Meyer, Andreas J; Reichheld, Jean-Philippe

    2016-02-01

    Thiol-disulfide redox regulation is essential for many cellular functions in plants. It has major roles in defense mechanisms, maintains the redox status of the cell and plays structural, with regulatory roles for many proteins. Although thiol-based redox regulation has been extensively studied in subcellular organelles such as chloroplasts, it has been much less studied in the nucleus. Thiol-disulfide redox regulation is dependent on the conserved redox proteins, glutathione/glutaredoxin (GRX) and thioredoxin (TRX) systems. We first focus on the functions of glutathione in the nucleus and discuss recent data concerning accumulation of glutathione in the nucleus. We also provide evidence that glutathione reduction is potentially active in the nucleus. Recent data suggests that the nucleus is enriched in specific GRX and TRX isoforms. We discuss the biochemical and molecular characteristics of these isoforms and focus on genetic evidences for their potential nuclear functions. Finally, we make an overview of the different thiol-based redox regulated proteins in the nucleus. These proteins are involved in various pathways including transcriptional regulation, metabolism and signaling. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  8. Membranes for Redox Flow Battery Applications

    Directory of Open Access Journals (Sweden)

    Maria Skyllas-Kazacos

    2012-06-01

    Full Text Available The need for large scale energy storage has become a priority to integrate renewable energy sources into the electricity grid. Redox flow batteries are considered the best option to store electricity from medium to large scale applications. However, the current high cost of redox flow batteries impedes the wide spread adoption of this technology. The membrane is a critical component of redox flow batteries as it determines the performance as well as the economic viability of the batteries. The membrane acts as a separator to prevent cross-mixing of the positive and negative electrolytes, while still allowing the transport of ions to complete the circuit during the passage of current. An ideal membrane should have high ionic conductivity, low water intake and excellent chemical and thermal stability as well as good ionic exchange capacity. Developing a low cost, chemically stable membrane for redox flow cell batteries has been a major focus for many groups around the world in recent years. This paper reviews the research work on membranes for redox flow batteries, in particular for the all-vanadium redox flow battery which has received the most attention.

  9. Membranes for Redox Flow Battery Applications

    Science.gov (United States)

    Prifti, Helen; Parasuraman, Aishwarya; Winardi, Suminto; Lim, Tuti Mariana; Skyllas-Kazacos, Maria

    2012-01-01

    The need for large scale energy storage has become a priority to integrate renewable energy sources into the electricity grid. Redox flow batteries are considered the best option to store electricity from medium to large scale applications. However, the current high cost of redox flow batteries impedes the wide spread adoption of this technology. The membrane is a critical component of redox flow batteries as it determines the performance as well as the economic viability of the batteries. The membrane acts as a separator to prevent cross-mixing of the positive and negative electrolytes, while still allowing the transport of ions to complete the circuit during the passage of current. An ideal membrane should have high ionic conductivity, low water intake and excellent chemical and thermal stability as well as good ionic exchange capacity. Developing a low cost, chemically stable membrane for redox flow cell batteries has been a major focus for many groups around the world in recent years. This paper reviews the research work on membranes for redox flow batteries, in particular for the all-vanadium redox flow battery which has received the most attention. PMID:24958177

  10. Developing a Metal Proxy for the Rise of Early Terrestrial Life

    Science.gov (United States)

    Rochelle, S. P.; Anbar, A. D.; Hartnett, H. E.; Romaniello, S. J.; Poret-Peterson, A. T.

    2015-12-01

    Previous work has shown that the presence of biological soil crusts (BSCs) may affect the concentrations of uranium and other transition metals by influencing metal dissolution, solubility, and transport.(1) These effects may provide a proxy for the presence of microbial mat communities in paleosols, possibly constraining the timing of the rise of early terrestrial ecosystems. Thus, in an effort to uncover possible biosignatures, this study examines metal abundances in modern desert BSCs as a possible analogue for early terrestrial life.We present results from a preliminary study comparing crusted and uncrusted soils from a low-desert site near Casa Grande, Arizona. Seventeen 5-cm soil cores were collected and the bulk elemental composition of the top 1 cm of crusted (9 samples) and non-crusted (8 samples) soils were analyzed by quadrupole ICP-MS with a typical measurement precision between 2-5%. Metal concentrations were normalized to aluminum (Al) to minimize dilution effects due to variations in carbonate and quartz content.Although the mean concentrations of nearly all elements were similar in crusted and uncrusted sites, the variability in the normalized concentrations of some of the elements, such as uranium, were different between crusted and uncrusted sites. The average U/Al ratio at the crusted site was 25 ± 1 μg U/ g Al and the average U/Al ratio at the uncrusted site was 27 ± 4 µg U/ g Al. Bartlett's and Levene's tests were used to confirm that the U/Al ratio was significantly more variable in the uncrusted sites as compared to the crusted sites. Iron (Fe), vanadium (V) and cesium (Cs) showed a similar pattern which was significant under Bartlett's but not Levene's test.As U, Fe, and V solubility and transport are redox-sensitive, we hypothesize that their aqueous mobility could have been impacted by diurnal redox swings in the photosynthetic crusts, possibly resulting in the homogenization of local cm-scale variations in background soil

  11. Proxy comparisons for Paleogene sea water temperature reconstructions

    Science.gov (United States)

    de Bar, Marijke; de Nooijer, Lennart; Schouten, Stefan; Ziegler, Martin; Sluijs, Appy; Reichart, Gert-Jan

    2017-04-01

    Several studies have reconstructed Paleogene seawater temperatures, using single- or multi-proxy approaches (e.g. Hollis et al., 2012 and references therein), particularly comparing TEX86 with foraminiferal δ18O and Mg/Ca. Whereas trends often agree relatively well, absolute temperatures can differ significantly between proxies, possibly because they are often applied to (extreme) climate events/transitions (e.g. Sluijs et al., 2011), where certain assumptions underlying the temperature proxies may not hold true. A more general long-term multi-proxy temperature reconstruction, is therefore necessary to validate the different proxies and underlying presumed boundary conditions. Here we apply a multi-proxy approach using foraminiferal calcite and organic proxies to generate a low-resolution, long term (80 Myr) paleotemperature record for the Bass River core (New Jersey, North Atlantic). Oxygen (δ18O), clumped isotopes (Δ47) and Mg/Ca of benthic foraminifera, as well as the organic proxies MBT'-CBT, TEX86H, U37K' index and the LDI were determined on the same sediments. The youngest samples of Miocene age are characterized by a high BIT index (>0.8) and fractional abundance of the C32 1,15-diol (>0.6; de Bar et al., 2016) and the absence of foraminifera, all suggesting high continental input and shallow depths. The older sediment layers (˜30 to 90 Ma) display BIT values and C32 1,15-diol fractional abundances global transition from the Cretaceous to Eocene greenhouse world into the icehouse climate. The TEX86H sea surface temperature (SST) record shows a gradual cooling over time of ˜35 to 20 ˚ C, whereas the δ18O-derived bottom water temperatures (BWTs) decrease from ˜20 to 10 ˚ C, and the Mg/Ca and Δ47-derived BWTs decrease from ˜25 to 15 ˚ C. The absolute temperature difference between the δ18O and Δ47, might be explained by local variations in seawater δ18O composition. Similarly, the difference in Mg/Ca- and δ18O-derived BWTs is likely caused by

  12. Time-and-ID-Based Proxy Reencryption Scheme

    Directory of Open Access Journals (Sweden)

    Kambombo Mtonga

    2014-01-01

    Full Text Available Time- and ID-based proxy reencryption scheme is proposed in this paper in which a type-based proxy reencryption enables the delegator to implement fine-grained policies with one key pair without any additional trust on the proxy. However, in some applications, the time within which the data was sampled or collected is very critical. In such applications, for example, healthcare and criminal investigations, the delegatee may be interested in only some of the messages with some types sampled within some time bound instead of the entire subset. Hence, in order to carter for such situations, in this paper, we propose a time-and-identity-based proxy reencryption scheme that takes into account the time within which the data was collected as a factor to consider when categorizing data in addition to its type. Our scheme is based on Boneh and Boyen identity-based scheme (BB-IBE and Matsuo’s proxy reencryption scheme for identity-based encryption (IBE to IBE. We prove that our scheme is semantically secure in the standard model.

  13. Benthic Redox Conditions and Oceanographic Variability in the Upper Central Peruvian Margin since the Nineteenth Century Depicted from Benthic Foraminifera

    Science.gov (United States)

    Cardich, J.; Sifeddine, A.; Salvatecci, R.; Briceño, F. J., Sr.; Almeida, C.; Romero, D.; Gutierrez, D.

    2014-12-01

    the period of coastal cooling and increasing fluxes of productivity proxies. Our findings suggest that besides export productivity, the upper margin benthic redox states are modulated by vertical mixing and/or subsurface ventilation.

  14. Changes in sedimentary redox associated with mussel (Mytilus edulis L. farms on the west-coast of Scotland.

    Directory of Open Access Journals (Sweden)

    Thomas A Wilding

    Full Text Available Aquaculture is growing rapidly in response to an increasing demand for protein and the over-exploitation of wild fisheries. Mussel (family Mytilidae production has doubled over the last decade and currently stands at 1.5 million tones production per annum. Mussels produce organic biodeposits which are dispersed around the production site and, potentially, impact the receiving environment in a number of inter-linked ways. The reported benthic impacts that occur, primarily through the accumulation of these biodeposits and associated organic enrichment, vary widely between studies. The objectives of this research were to determine the nature of the relationship between sediment redox (a proxy for oxygenation and farm-proximity and covariables whilst accounting for, and quantifying, differences in redox between sites. Sediment cores (N = 159 were taken remotely around a random sample of mussel farms, redox was measured at 10 mm sediment depth and linked to farm-distance and sediment organic/shell content and particle size, using an additive, mixed, weighted regression model. Redox varied considerably between sites and there was a highly significant reduction (50 mV in redox adjacent to the mussel lines. Redox increased non-linearly with distance, rising rapidly at >7 m from the farm edge. The modest reduction in sediment oxygenation in close proximity to mussel farms reported here suggests that farms located over sediments characterised by pre-existing oxygen stress are likely to exacerbate benthic species impoverishment associated with reducing sedimentary conditions whilst those located over highly oxygenated sediments are likely to increase benthic productivity.

  15. A new way to proxy levels of infrastructure development

    Directory of Open Access Journals (Sweden)

    Steve Pickering

    2017-01-01

    Full Text Available Researchers in many fields have needed to develop a measure of infrastructure, and many proxies have been used toward this end, such as night light data and the Digital Chart of the World. Yet there are issues in using these methods. This paper presents a new way of proxying infrastructure: analysing the file sizes of map images on the Bing, Google, OpenStreetMap and Sina websites. The paper also demonstrates four ways in which this can be achieved. This approach is by no means perfect and does not solve all of the difficulties presented by other methods. Nevertheless, it does provide a simple and functional alternative proxy for level of infrastructure development.

  16. Munchausen Syndrome By Proxy Admitting with Bloody Urine and Stool

    Directory of Open Access Journals (Sweden)

    Tugba Koca

    2014-02-01

    Full Text Available Munchausen syndrome by Proxy is a severe form of child abuse. Disease symptoms and signs are fabricated or imitated by parents or caregivers The child is usually presented to doctors, persistently. A delay in diagnosis may cause severe negative impact on spiritual, physical, mental and social development of the cases and even death. Symptoms usually disappear in the absence of the perpetrators. The diagnosis is extremely difficult. A 21-month-old boy who had applied to many centers due to bleeding from various parts of the body for last six months, and whose symptoms could not be explained with any physical reason after tests were conducted. Finally he was admitted to our center with bloody urine and stools, and diagnosed Munchausen syndrome by proxy. In cases with recurrent hospital admission in whom no apparent disease is diagnosed, Munchausen syndrome by Proxy should be among the differential diagnosis.

  17. Research on implementation of proxy Arp in IP DSLAM

    Science.gov (United States)

    Cheng, Chuanqing; Wang, Li; Huang, Qiugen

    2005-02-01

    While the ethernet is applied more and more in public network environment and xdsl service become the most common access mode ,IP kenel DSLAM undertakes some functions such as service distribution and convergence ,security management and customer management.Facing the contradiction of the need of port isolation and the shortage of ip address,VLAN aggregation technology is applied in DSLAM.How to implement the communicatio between the two vlan but share the same ip subnet,proxy arp does this. This paper introduces how to implement proxy arp in the DSLAM. TCP/IP communication detail procedure betweent two host ,the relation of VLAN and network segment are discussed. The proxy arp model and its implementation in IP DSLAM is also expatiated in this paper and a conformance tesing is given.

  18. Resurgence: Response competition, stimulus control, and reinforcer control.

    Science.gov (United States)

    Podlesnik, Christopher A; Kelley, Michael E

    2014-09-01

    Resurgence is the relapse of a previously reinforced and then extinguished target response when extinguishing a more recently reinforced alternative response. We designed the present study to assess the contribution of stimulus-control and reinforcer-control processes in determining resurgence. In a modified resurgence procedure, we removed the alternative discriminative stimulus signaling alternative reinforcement when extinguishing the alternative response. This produced more abrupt resurgence of target responding than in a typical resurgence procedure maintaining the alternative discriminative stimulus when extinguishing the alternative response. The overall amount of resurgence did not differ. Importantly, a "renewal" control added and removed the alternative stimulus during extinction, identically as in the modified resurgence procedure. However, alternative responding was never reinforced, which produced no relapse of target responding. Therefore, the more abrupt resurgence with the modified procedure than with the typical procedure suggests removing the alternative stimulus reduced the competition between alternative and target responding. These findings revealed the importance of adding and removing alternative reinforcement in producing resurgence (reinforcer control) but little influence of simply adding and removing the alternative stimulus (stimulus control). These data suggest that clinicians should consider the long-term availability of the alternative response option when developing differential-reinforcement interventions. © Society for the Experimental Analysis of Behavior.

  19. Redox interplay between mitochondria and peroxisomes

    Directory of Open Access Journals (Sweden)

    Celien eLismont

    2015-05-01

    Full Text Available Reduction-oxidation or ‘redox’ reactions are an integral part of a broad range of cellular processes such as gene expression, energy metabolism, protein import and folding, and autophagy. As many of these processes are intimately linked with cell fate decisions, transient or chronic changes in cellular redox equilibrium are likely to contribute to the initiation and progression of a plethora of human diseases. Since a long time, it is known that mitochondria are major players in redox regulation and signaling. More recently, it has become clear that also peroxisomes have the capacity to impact redox-linked physiological processes. To serve this function, peroxisomes cooperate with other organelles, including mitochondria. This review provides a comprehensive picture of what is currently known about the redox interplay between mitochondria and peroxisomes in mammals. We first outline the pro- and antioxidant systems of both organelles and how they may function as redox signaling nodes. Next, we critically review and discuss emerging evidence that peroxisomes and mitochondria share an intricate redox-sensitive relationship and cooperate in cell fate decisions. Key issues include possible physiological roles, messengers, and mechanisms. We also provide examples of how data mining of publicly-available datasets from ‘omics’ technologies can be a powerful means to gain additional insights into potential redox signaling pathways between peroxisomes and mitochondria. Finally, we highlight the need for more studies that seek to clarify the mechanisms of how mitochondria may act as dynamic receivers, integrators, and transmitters of peroxisome-derived mediators of oxidative stress. The outcome of such studies may open up exciting new avenues for the community of researchers working on cellular responses to organelle-derived oxidative stress, a research field in which the role of peroxisomes is currently highly underestimated and an issue of

  20. Probing redox states in the ancient and modern crust and possible biosphere-lithosphere interactions

    Science.gov (United States)

    Trail, D.

    2015-12-01

    The oxidation states of modern-day terrestrial environments are broadly constrained, though we are at the earliest stages of directly quantifying redox states during the first 700 million years. Redox states are constrainable through a combination of high temperature laboratory experiments, analyses of detrital Hadean zircon, and younger well-studied zircons and their host rocks. The redox state of the solid earth and the biosphere are believed to be interwoven: how might we exploit this to probe for the existence of possible biosphere-lithosphere interactions on the early Earth? Some insight comes from the investigation of "modern-day" zircon-bearing rocks and the new application of techniques that allow us to directly probe element valence as a proxy for magma redox state (XANES). Other insights are possible through the study of young ~400 Ma (S)edimentary- and (I)gneous-type granitoids from Lachlan Fold Belt (LFB), where the magma chemical properties in the former may be influenced by the assimilation of sedimentary material containing organic matter. We observe that zircons from LFB S-type granitoids formed under more reducing conditions when compared to LFB zircon formed in I-type granitoids. This observation, while reflecting 9 granitoids and 289 analyses of zircons where over 400 different plutons have been identified, is consistent with the incorporation of (reduced) organic matter in the former and highlights one possible manner in which life may influence the composition of igneous minerals. The chemical properties of rocks or igneous minerals such as zircon may extend the search for ancient biological activity to the earliest period of known igneous activity, which dates back to ~4.4 billion years ago. If organic matter was incorporated into Hadean sediments that were then buried and melted, then these biological remnants could imprint a chemical signature within the subsequent melt and the resulting crystal assemblage, including zircon.

  1. "Chameleon" Macromolecules: Synthesis, Structures and Applications of Stimulus Responsive Polymers

    NARCIS (Netherlands)

    Sui, Xiaofeng

    2012-01-01

    This thesis describes the preparation and characterization of addressable responsive polymer structures and their versatile applications. Stimuli responsive polymer chains including temperature responsive poly(N-isopropylacrylamide), PNIPAM, pH responsive poly(methacrylic acid), PMAA and redox

  2. Sound localization: effects of reverberation time, speaker array, stimulus frequency, and stimulus rise/decay.

    Science.gov (United States)

    Giguère, C; Abel, S M

    1993-08-01

    This research assessed the ability of human listeners to localize one-third octave noise bands in the horizontal plane. The effects of reverberation time (absorbent versus reverberant room), stimulus center frequency (500, 1000, 2000, and 4000 Hz), stimulus rise/decay time (5 vs 200 ms) and speaker array (frontal versus lateral) were investigated for four subjects using a forced-choice speaker-identification paradigm. Sound localization scores were consistently lower in the reverberant room than in the absorbent room. They also revealed strong frequency and azimuthal effects. The benefit of a shorter rise/decay time was small and limited to low frequencies. The identification of a speaker position depended strongly upon the array in which it was embedded, primarily because localization in the lateral array led to frequency-dependent front/back confusions and response bias. The results also illustrated the importance of choosing a coordinate system based on the auditory cone-of-confusion to analyze localization data for speaker arrays spanning the aural axis.

  3. Health anxiety by proxy in women with severe health anxiety

    DEFF Research Database (Denmark)

    Thorgaard, Mette Viller; Frostholm, Lisbeth; Walker, Lynn

    2017-01-01

    Health anxiety (HA) refers to excessive worries and anxiety about harbouring serious illness based on misinterpretation of bodily sensations or changes as signs of serious illness. Severe HA is associated with disability and high health care costs. However, the impact of parental HA on excessive...... concern with their children's health (health anxiety by proxy) is scantly investigated. The aim of this study is to investigate HA by proxy in mothers with severe HA. Fifty mothers with severe HA and two control groups were included, i.e. mothers with rheumatoid arthritis (N = 49) and healthy mothers (N...

  4. Gamma oscillatory amplitude encodes stimulus intensity in primary somatosensory cortex

    Directory of Open Access Journals (Sweden)

    Holly Elizabeth Rossiter

    2013-07-01

    Full Text Available Gamma oscillations have previously been linked to pain perception and it has been hypothesised that they may have a potential role in encoding pain intensity. Stimulus response experiments have reported an increase in activity in the primary somatosensory cortex (SI with increasing stimulus intensity, but the specific role of oscillatory dynamics in this change in activation remains unclear. In this study, Magnetoencephalography (MEG was used to investigate the changes in cortical oscillations during 4 different intensities of a train of electrical stimuli to the right index finger, ranging from low sensation to strong pain. In those participants showing changes in evoked oscillatory gamma in SI during stimulation, the strength of the gamma power was found to increase with increasing stimulus intensity at both pain and sub-pain thresholds. These results suggest that evoked gamma oscillations in SI are not specific to pain but may have a role in encoding somatosensory stimulus intensity.

  5. The rapid emergence of stimulus specific perceptual learning

    Directory of Open Access Journals (Sweden)

    Zahra eHussain

    2012-07-01

    Full Text Available Is stimulus specific perceptual learning the result of extended practice or does it emerge early in the time course of learning? We examined this issue by manipulating the amount of practice given on a face identification task on Day 1, and altering the familiarity of stimuli on Day 2. We found that a small number of trials was sufficient to produce stimulus specific perceptual learning of faces: on Day 2, response accuracy decreased by the same amount for novel stimuli regardless of whether observers practiced 105 or 840 trials on Day 1. Current models of learning assume early procedural improvements followed by late stimulus specific gains. Our results show that stimulus specific and procedural improvements are distributed throughout the time course of learning

  6. Promoting response variability and stimulus generalization in martial arts training

    National Research Council Canada - National Science Library

    Harding, Jay W; Wacker, David P; Berg, Wendy K; Rick, Gary; Lee, John F

    2004-01-01

    The effects of reinforcement and extinction on response variability and stimulus generalization in the punching and kicking techniques of 2 martial arts students were evaluated across drill and sparring conditions...

  7. Input Deficit and Stimulus Enrichment: A Replication-with-Expansion

    Science.gov (United States)

    Friedrich, Douglas; And Others

    1973-01-01

    Two studies were conducted based on a methodological criticism of J. Gordon and H. Haywood's (1969) research on stimulus enrichment procedures with cultural-familial and brain-damaged retarded persons. (Author)

  8. Educational Implications of Stimulus Overselectivity in Autistic Children.

    Science.gov (United States)

    Dunlap, Glen; And Others

    1981-01-01

    Research is reviewed on stimulus overselectivity in autistic children, and educational implications are discussed in terms of language acquisition, social behavior, observational learning, generalization, and prompting and prompt fading. Approaches to circumvent the problem of overselectivity are also described. (CL)

  9. Auditory Stimulus Equivalence and Non-Arbitrary Relations

    National Research Council Canada - National Science Library

    Stewart, Ian; Lavelle, Niamh

    2013-01-01

    This study extended previous research on stimulus equivalence with all auditory stimuli by using a methodology more similar to conventional match-to-sample training and testing for three 3-member equivalence relations...

  10. The Stimulus Movement Effect: Allocation of Attention or Artifact?

    Science.gov (United States)

    Washburn, David A.

    1993-01-01

    In previous reports, including one by the author, learning has been shown to benefit by having discriminanda move rather than remain stationary. This stimulus movement effect might be attributed to several theoretical mechanisms, including attention, topological memory, and exposure duration. The series of experiments reported in this article was designed to Contrast these potential explanatory factors. Ten rhesus monkeys (Macaca mulatta) were tested on a variety of computerized tasks in which the stimuli remained stationary, flashed, or moved at systematically varied speeds. Performance was significantly best when the sample stimulus moved quickly and was poorest when the stimulus remained stationary. Further analysis of these data and other previously published data revealed that the distribution of the stimulus movement effect across trials supported an attention allocation interpretation.

  11. Learned helplessness as conditioned inattention to the target stimulus.

    Science.gov (United States)

    Barber, J G; Winefield, A H

    1986-09-01

    Learned helplessness theory explains the impaired performance that follows exposure to uncontrollable outcomes by assuming learned expectation of response-outcome independence that is transferred between tasks. Recent evidence has shown that introducing a second neutral stimulus, contingent on the offset of the uncontrollable stimulus, removes the subsequent interference. This finding has been claimed to support the view that the interference is a result of conditioned inattention rather than of the expectation of response-outcome independence. These conflicting explanations were examined in a series of four experiments that varied induction procedures (passive exposure or inescapability) and stimulus quality (aversive or nonaversive). All four experiments found the predicted interference, but only one, in which passive exposure was combined with an aversive stimulus, obtained results supporting the conditioned inattention hypothesis. We conclude that learned helplessness probably involves more than a single mechanism and that the passive exposure procedure may not be appropriate for demonstrating genuine helplessness deficits.

  12. Redox storage systems for solar applications

    Science.gov (United States)

    Hagedorn, N. H.; Thaller, L. H.

    1981-01-01

    It is noted that the worldwide development of solar photovoltaic and wind turbine systems to meet a range of terrestrial electrical energy requirements has underscored the need for inexpensive and reliable electrical energy storage. The NASA Redox Energy Storage System, based on soluble aqueous iron and chromium chloride redox couples, has exhibited many system-related features which for the most part are unique to this storage system. The technology advances required in the two elements (electrodes and membranes), which are the key to its technological feasibility, have been attained and system development has begun. The design, construction, and testing of a 1-kW system integrated with a solar photovoltaic array is underway to provide early demonstration of the attractive system-related features of the NASA Redox Storage System. Also demonstrated will be its versatility and compatibility with a terrestrial solar photovoltaic electric power system.

  13. Potentiometric Measurements of Semiconductor Nanocrystal Redox Potentials.

    Science.gov (United States)

    Carroll, Gerard M; Brozek, Carl K; Hartstein, Kimberly H; Tsui, Emily Y; Gamelin, Daniel R

    2016-04-06

    A potentiometric method for measuring redox potentials of colloidal semiconductor nanocrystals (NCs) is described. Fermi levels of colloidal ZnO NCs are measured in situ during photodoping, allowing correlation of NC redox potentials and reduction levels. Excellent agreement is found between electrochemical and optical redox-indicator methods. Potentiometry is also reported for colloidal CdSe NCs, which show more negative conduction-band-edge potentials than in ZnO. This difference is highlighted by spontaneous electron transfer from reduced CdSe NCs to ZnO NCs in solution, with potentiometry providing a measure of the inter-NC electron-transfer driving force. Future applications of NC potentiometry are briefly discussed.

  14. Slices: A shape-proxy based on planar sections

    KAUST Repository

    McCrae, James

    2011-12-01

    Minimalist object representations or shape-proxies that spark and inspire human perception of shape remain an incompletely understood, yet powerful aspect of visual communication. We explore the use of planar sections, i.e., the contours of intersection of planes with a 3D object, for creating shape abstractions, motivated by their popularity in art and engineering. We first perform a user study to show that humans do define consistent and similar planar section proxies for common objects. Interestingly, we observe a strong correlation between user-defined planes and geometric features of objects. Further we show that the problem of finding the minimum set of planes that capture a set of 3D geometric shape features is both NP-hard and not always the proxy a user would pick. Guided by the principles inferred from our user study, we present an algorithm that progressively selects planes to maximize feature coverage, which in turn influence the selection of subsequent planes. The algorithmic framework easily incorporates various shape features, while their relative importance values are computed and validated from the user study data. We use our algorithm to compute planar slices for various objects, validate their utility towards object abstraction using a second user study, and conclude showing the potential applications of the extracted planar slice shape proxies.

  15. Proxy indicators as measure of local economic dispositions in South ...

    African Journals Online (AJOL)

    Even though South Africa is in a more fortunate position with regard to the availability of such data, it also has data gaps, notably with regard to informal economic activities in the rural areas of the country. This exploratory article engages the use of proxy indicators to provide cues as to the state of a local economy.

  16. Proxy indicators as measure of local economic dispositions in South ...

    African Journals Online (AJOL)

    The growth of spare-part sales mirrors the behaviour of the national economy more accurately than used and new vehicles. BER: Retail Survey. (2005-2010). Used vehicles. 0.53. Spare Parts. 0.80. Banking-related proxy indicators. 13. House bonds. 0.43. Although some similarities exist between the national economy and ...

  17. Munchausen Syndrome by Proxy: A Study of Psychopathology.

    Science.gov (United States)

    Bools, Christopher; And Others

    1994-01-01

    This study evaluated 100 mothers with Munchausen Syndrome by Proxy (the fabrication of illness by a mother in her child). Approximately half of the mothers had either smothered or poisoned their child as part of their fabrications. Lifetime psychiatric histories were reported for 47 of the mothers. The most notable psychopathology was personality…

  18. Munchausen Syndrome by Proxy: Mother Fabricates Infant's Hearing Impairment.

    Science.gov (United States)

    Kahn, Gerri; Goldman, Ellen

    1991-01-01

    Case study reports a case of Munchausen Syndrome by Proxy, a form of child abuse in which the mother presents a child for treatment for a condition she herself has invented or created. This case study describes the ways in which a mother obtained a diagnosis of sensorineural hearing loss as well as amplification for her normally hearing infant.…

  19. Munchausen syndrome by adult proxy: a review of the literature.

    Science.gov (United States)

    Burton, M Caroline; Warren, Mark B; Lapid, Maria I; Bostwick, J Michael

    2015-01-01

    Munchausen syndrome by proxy (MSBP), more formally known as factitious disorder imposed on another, is a form of abuse in which a caregiver deliberately produces or feigns illness in a person under his or her care so that the proxy will receive medical care that gratifies the caregiver. Although well documented in the pediatric literature, few cases of MSBP with adult proxies (MSB-AP) have been reported. This study reviews existing literature on MSB-AP to provide a framework for clinicians to recognize this disorder. We searched Ovid MEDLINE, Ovid EMBASE, PubMed, Web of Knowledge, and PsychINFO, supplemented by bibliographic examination. We identified 13 cases of MSB-AP. Perpetrators were caregivers, most (62%) were women, and many worked in healthcare. The age range of the victims was 21 to 82 years. Most were unaware of the abuse, although in 2 cases the victim may have colluded with the perpetrator. Disease fabrication most often resulted from poisoning. MSB-AP should be included in the differential diagnosis of patients presenting with a complex constellation of symptoms without a unifying etiology and an overly involved caregiver with suspected psychological gain. Early identification is necessary so that healthcare providers do not unknowingly perpetuate harm through treatments that satisfy the perpetrator's psychological needs at the proxy's expense. © 2014 Society of Hospital Medicine.

  20. Identifying and Responding to Munchausen Syndrome by Proxy.

    Science.gov (United States)

    Pearl, Peggy T.

    1995-01-01

    Defines Munchausen Syndrome by Proxy in children up to eight years, in which the mother falsifies illness in her child by simulating or producing illness, bringing about frequent hospitalizations, painful tests, potentially harmful treatment, and in extreme cases, death. Describes symptoms and suggested professional actions. (DR)

  1. Munchausen by Proxy Victims in Adulthood: A First Look.

    Science.gov (United States)

    Libow, Judith A.

    1995-01-01

    Childhood experiences and long-term psychological outcomes were investigated with 10 adults, ages 33 through 71, who were self-identified victims of illness fabrication by a parent (Munchausen by Proxy). During childhood they felt unloved and unsafe and had emotional and physical problems. As adults, problems included insecurity, reality-testing…

  2. Munchausen Syndrome by Proxy (MSBP): An Intergenerational Perspective.

    Science.gov (United States)

    Rappaport, Sol R.; Hochstadt, Neil J.

    1993-01-01

    Presents new information about Munchausen Syndrome by Proxy (MSBP), factitious disorder in which caretaker may induce or exaggerate medical illness in his or her child that may lead to illness and even death. Provides psychosocial history of caregiver using intergenerational model. Presents case of MSBP involving three siblings and information…

  3. Shareholder Activism through Proxy Proposals : The European Perspective

    NARCIS (Netherlands)

    Cziraki, P.; Renneboog, L.D.R.; Szilagyi, P.G.

    2009-01-01

    This paper is the first to investigate the corporate governance role of shareholderinitiated proxy proposals in European firms. While proposals in the US are nonbinding even if they pass the shareholder vote, they are legally binding in the UK and most of Continental Europe. Nonetheless, submissions

  4. A comparison of Solar proxy-magnetometry diagnostics

    NARCIS (Netherlands)

    Leenaarts, J.|info:eu-repo/dai/nl/304837946; Rutten, R.J.|info:eu-repo/dai/nl/074143662; Carlsson, M.; Uitenbroek, H.

    2006-01-01

    Aims. We test various proxy-magnetometry diagnostics, i.e., brightness signatures of small-scale magnetic elements, for studying magnetic field structures in the solar photosphere. Methods. Images are numerically synthesized from a 3D solar magneto-convection simulation for, respectively, the G band

  5. Munchausen by Proxy (MBP) Maltreatment: An International Educational Challenge.

    Science.gov (United States)

    Lasher, Louisa J.

    2003-01-01

    This article is an introduction to a special section on Munchausen Syndrome by Proxy (MSBP) as a form of child maltreatment. In MSBP the perpetrator has deliberately induced, fabricated, or exaggerated a physical and/or psychological-behavioral-mental health problem in another. The article stresses the importance of obtaining an MSBP finding of…

  6. The Impact of Stimulus Presentation and Size on Preference.

    Science.gov (United States)

    Moore, James W; Radley, Keith C; Dart, Evan H; Whipple, Heather M; Ness, Emily J; Murphy, Ashley N; Furlow, Chris; Wimberly, Joy K; Smith, Ashley

    2017-06-01

    The impact of stimulus size and presentation on choice during a preference assessment was investigated using a modified multiple-stimulus without replacement (MSWO) technique. Stimuli were either presented with a uniform magnitude, as determined by mass, or in a manner consistent with caregiver report of reinforcer consumption. While both assessment procedures identified the same top three preferred items in three out of five cases, greater variability in the preference rank of less preferred items was observed between assessments.

  7. Gamma oscillatory amplitude encodes stimulus intensity in primary somatosensory cortex

    OpenAIRE

    Holly Elizabeth Rossiter; Worthen, Sian F.; Caroline eWitton; Hall, Stephen D.; Furlong, Paul L

    2013-01-01

    Gamma oscillations have previously been linked to pain perception and it has been hypothesised that they may have a potential role in encoding pain intensity. Stimulus response experiments have reported an increase in activity in the primary somatosensory cortex (SI) with increasing stimulus intensity, but the specific role of oscillatory dynamics in this change in activation remains unclear. In this study, Magnetoencephalography (MEG) was used to investigate the changes in cortical oscillati...

  8. Psilocybin-induced stimulus control in the rat

    OpenAIRE

    Winter, J. C.; Rice, K. C.; Amorosi, D. J.; Rabin, R. A.

    2007-01-01

    Although psilocybin has been trained in the rat as a discriminative stimulus, little is known of the pharmacological receptors essential for stimulus control. In the present investigation rats were trained with psilocybin and tests were then conducted employing a series of other hallucinogens and presumed antagonists. An intermediate degree of antagonism of psilocybin was observed following treatment with the 5-HT2A receptor antagonist, M100907. In contrast, no significant antagonism was obse...

  9. SINOMA - a better tool for proxy based reconstructions?

    Science.gov (United States)

    Buras, Allan; Thees, Barnim; Czymzik, Markus; Dräger, Nadine; Kienel, Ulrike; Neugebauer, Ina; Ott, Florian; Scharnweber, Tobias; Simard, Sonia; Slowinski, Michal; Slowinski, Sandra; Tecklenburg, Christina; Zawiska, Izabela; Wilmking, Martin

    2014-05-01

    Our knowledge on past environmental conditions largely relies on reconstructions that are based on linear regressions between proxy variables (e.g. tree-rings, lake sediments, ice cores) covering a comparably long period (centuries to millennia) and environmental parameters (e.g. climate data) of which only rather short measurement series exist (mostly decades). In general, the corresponding measurements are prone to errors. For instance, air temperature records that are to be prolonged by reconstruction from tree-rings are normally not measured in situ, i.e. where the trees used for reconstructions are growing. In contrast, the variation of tree-ring properties which are used as proxies does not only depend on temperature variations but also on other environmental variables and biological effects. However, if regressions are based on noisy data, knowledge on the noise intensity of both predictor and predictand is needed and model parameter estimates (slope and intercept) will be erroneous if information on the noise is not included in their estimation (Kutzbach et al., 2011). Here, we investigate the performance of the new Sequential Iterative Noise Matching Algorithm (SINOMA; Thees et al., 2009; and Thees et al., submitted) on a variety of typical proxy-data of differing temporal resolution (i.e. hourly (dendrometers, piezometers), seasonally (tree-rings), and annually (tree rings and varved lake sediments)). For each of the investigated proxies a number of pseudo-proxy datasets is generated. I.e. to each proxy variable two different noises are added, resulting in two noisy variables that originate from a common signal (the proxy) and of which the respective error noises and the true model parameters (slope and intercept) between both are known. SINOMA is applied to each of these pseudo-proxy datasets and its performance is evaluated against traditional regression techniques. The herewith submitted contribution thus focuses on the applicability of SINOMA rather

  10. P3a, perceptual distinctiveness, and stimulus modality.

    Science.gov (United States)

    Comerchero, M D; Polich, J

    1998-07-01

    A three-stimulus oddball paradigm (target, standard, nontarget) was employed in which subjects responded to an infrequent target, when its discrimination from the frequent standard was difficult. In separate auditory and visual modality conditions, the stimulus characteristics of an infrequent nontarget were manipulated such that its perceptual distinctiveness from the target was varied systematically. For both the low and high distinctiveness conditions, target stimulus P300 amplitude was larger than the nontarget only at the parietal electrode. In contrast, nontarget P3a amplitude was larger and earlier than the target P300 over the frontal/central electrode sites. The distinctiveness manipulation between the target and nontarget produced larger P3a component profiles for the auditory compared to visual stimuli. The results support previous findings that target/standard stimulus context determines P3a generation for both auditory and visual stimulus modalities and suggest that the distinctiveness of the eliciting stimulus contributes to P3a amplitude. Theoretical implications are discussed. Copyright 1998 Elsevier Science B.V.

  11. Effects of orientation and differential reinforcement on transitive stimulus control.

    Science.gov (United States)

    Amd, Micah; de Almeida, João H; de Rose, Júlio C; Silveira, Carolina C; Pompermaier, Henrique M

    2017-11-01

    The emergence of transitive relations between stimuli that had never appeared together is a key process underlying concept formation. An unresolved theoretical issue with respect to transitive relations has been to determine whether differential reinforcement of stimulus-stimulus (S-S) relations though matching-to-sample, or contiguous S-S correlations/pairings, is more critical for producing transitivity. The current study inquired whether simple environmental S-S pairings, versus differential reinforcement of S-S relations, versus environmental S-S pairings with an orientation requirement, produced the greatest instances of transitivity. 12 groups of participants were parsed into one of four procedures (matching-to-sample, stimulus-paring, stimulus-pairing-w/response, stimulus-pairing-w/orientation) along one of three training structures (linear, many-to-one, one-to-many). All participants underwent a fixed number of training trials for establishing three, three-member stimulus sets (A1B1C1, A2B2C2, A3B3C3), followed by a single sorting test for AC transitivity. Our results demonstrate orienting towards environmental S-S pairings yield the greatest degree of transitivity. The effectivity of pairing procedures for establishing transitive relations, particularly when compared to matching-to-sample, can inform the development of educational interventions for individuals for whom the latter procedure (involving differential reinforcement) is ineffective. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Effect of long-term fertilization on humic redox mediators in multiple microbial redox reactions.

    Science.gov (United States)

    Guo, Peng; Zhang, Chunfang; Wang, Yi; Yu, Xinwei; Zhang, Zhichao; Zhang, Dongdong

    2018-03-01

    This study investigated the effects of different long-term fertilizations on humic substances (HSs), humic acids (HAs) and humins, functioning as redox mediators for various microbial redox biotransformations, including 2,2',4,4',5,5'- hexachlorobiphenyl (PCB 153 ) dechlorination, dissimilatory iron reduction, and nitrate reduction, and their electron-mediating natures. The redox activity of HSs for various microbial redox metabolisms was substantially enhanced by long-term application of organic fertilizer (pig manure). As a redox mediator, only humin extracted from soils with organic fertilizer amendment (OF-HM) maintained microbial PCB 153 dechlorination activity (1.03 μM PCB 153 removal), and corresponding HA (OF-HA) most effectively enhanced iron reduction and nitrate reduction by Shewanella putrefaciens. Electrochemical analysis confirmed the enhancement of their electron transfer capacity and redox properties. Fourier transform infrared analysis showed that C=C and C=O bonds, and carboxylic or phenolic groups in HSs might be the redox functional groups affected by fertilization. This research enhances our understanding of the influence of anthropogenic fertility on the biogeochemical cycling of elements and in situ remediation ability in agroecosystems through microorganisms' metabolisms. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. On the use of human mobility proxies for modeling epidemics.

    Directory of Open Access Journals (Sweden)

    Michele Tizzoni

    2014-07-01

    Full Text Available Human mobility is a key component of large-scale spatial-transmission models of infectious diseases. Correctly modeling and quantifying human mobility is critical for improving epidemic control, but may be hindered by data incompleteness or unavailability. Here we explore the opportunity of using proxies for individual mobility to describe commuting flows and predict the diffusion of an influenza-like-illness epidemic. We consider three European countries and the corresponding commuting networks at different resolution scales, obtained from (i official census surveys, (ii proxy mobility data extracted from mobile phone call records, and (iii the radiation model calibrated with census data. Metapopulation models defined on these countries and integrating the different mobility layers are compared in terms of epidemic observables. We show that commuting networks from mobile phone data capture the empirical commuting patterns well, accounting for more than 87% of the total fluxes. The distributions of commuting fluxes per link from mobile phones and census sources are similar and highly correlated, however a systematic overestimation of commuting traffic in the mobile phone data is observed. This leads to epidemics that spread faster than on census commuting networks, once the mobile phone commuting network is considered in the epidemic model, however preserving to a high degree the order of infection of newly affected locations. Proxies' calibration affects the arrival times' agreement across different models, and the observed topological and traffic discrepancies among mobility sources alter the resulting epidemic invasion patterns. Results also suggest that proxies perform differently in approximating commuting patterns for disease spread at different resolution scales, with the radiation model showing higher accuracy than mobile phone data when the seed is central in the network, the opposite being observed for peripheral locations. Proxies

  14. On the use of human mobility proxies for modeling epidemics.

    Science.gov (United States)

    Tizzoni, Michele; Bajardi, Paolo; Decuyper, Adeline; Kon Kam King, Guillaume; Schneider, Christian M; Blondel, Vincent; Smoreda, Zbigniew; González, Marta C; Colizza, Vittoria

    2014-07-01

    Human mobility is a key component of large-scale spatial-transmission models of infectious diseases. Correctly modeling and quantifying human mobility is critical for improving epidemic control, but may be hindered by data incompleteness or unavailability. Here we explore the opportunity of using proxies for individual mobility to describe commuting flows and predict the diffusion of an influenza-like-illness epidemic. We consider three European countries and the corresponding commuting networks at different resolution scales, obtained from (i) official census surveys, (ii) proxy mobility data extracted from mobile phone call records, and (iii) the radiation model calibrated with census data. Metapopulation models defined on these countries and integrating the different mobility layers are compared in terms of epidemic observables. We show that commuting networks from mobile phone data capture the empirical commuting patterns well, accounting for more than 87% of the total fluxes. The distributions of commuting fluxes per link from mobile phones and census sources are similar and highly correlated, however a systematic overestimation of commuting traffic in the mobile phone data is observed. This leads to epidemics that spread faster than on census commuting networks, once the mobile phone commuting network is considered in the epidemic model, however preserving to a high degree the order of infection of newly affected locations. Proxies' calibration affects the arrival times' agreement across different models, and the observed topological and traffic discrepancies among mobility sources alter the resulting epidemic invasion patterns. Results also suggest that proxies perform differently in approximating commuting patterns for disease spread at different resolution scales, with the radiation model showing higher accuracy than mobile phone data when the seed is central in the network, the opposite being observed for peripheral locations. Proxies should therefore be

  15. Disentangling sequential effects of stimulus- and response-related conflict and stimulus-response repetition using brain potentials.

    Science.gov (United States)

    Wendt, Mike; Heldmann, Marcus; Münte, Thomas F; Kluwe, Rainer H

    2007-07-01

    Conflict monitoring theory holds that detection of conflicts in information processing by the anterior cingulate cortex (ACC) results in processing adaptation that minimizes subsequent conflict. Applying an Eriksen f lanker task with four stimuli mapped onto two responses, we investigated whether such modulation occurs only after response-related or also after stimulus-related conflict, focusing on the N2 component of the event-related potential. Contrasting with previous findings, both stimulus- and response-related conflict elicited enhancement of the N2, suggesting that the ACC is sensitive to conflict at both the stimulus and the response level. However, neither type of conflict resulted in reduced conflict effects on the following trial when stimulus-response (S-R) sequence effects were controlled by excluding identical S-R repetition trials. Identical S-R repetitions were associated with facilitated processing, thus demonstrating that inclusion of these trials in the analysis may mimic results predicted by the conflict adaptation hypothesis.

  16. Training methods for horses: habituation to a frightening stimulus.

    Science.gov (United States)

    Christensen, J W; Rundgren, M; Olsson, K

    2006-09-01

    Responses of horses in frightening situations are important for both equine and human safety. Considerable scientific interest has been shown in development of reactivity tests, but little effort has been dedicated to the development of appropriate training methods for reducing fearfulness. To investigate which of 3 different training methods (habituation, desensitisation and counter-conditioning) was most effective in teaching horses to react calmly in a potentially frightening situation. 1) Horses are able to generalise about the test stimulus such that, once familiar with the test stimulus in one situation, it appears less frightening and elicits a reduced response even when the stimulus intensity is increased or the stimulus is presented differently; and 2) alternative methods such as desensitisation and counter-conditioning would be more efficient than a classic habituation approach. Twenty-seven naive 2-year-old Danish Warmblood stallions were trained according to 3 different methods, based on classical learning theory: 1) horses (n = 9) were exposed to the full stimulus (a moving, white nylon bag, 1.2 x 0.75 m) in 5 daily training sessions until they met a predefined habituation criterion (habituation); 2) horses (n = 9) were introduced gradually to the stimulus and habituated to each step before the full stimulus was applied (desensitisation); 3) horses (n = 9) were trained to associate the stimulus with a positive reward before being exposed to the full stimulus (counter-conditioning). Each horse received 5 training sessions of 3 min per day. Heart rate and behavioural responses were recorded. Horses trained with the desensitisation method showed fewer flight responses in total and needed fewer training sessions to learn to react calmly to test stimuli. Variations in heart rate persisted even when behavioural responses had ceased. In addition, all horses on the desensitisation method eventually habituated to the test stimulus whereas some horses on the

  17. Biogeochemical Barriers: Redox Behavior of Metals and Metalloids

    Science.gov (United States)

    Redox conditions and pH are arguably the most important geochemical parameters that control contaminant transport and fate in groundwater systems. Oxidation-reduction (redox) reactions mediate the chemical behavior of both inorganic and organic chemical constituents by affecting...

  18. Characterization of redox conditions in groundwater contaminant plumes

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Bjerg, Poul Løgstrup; Banwarth, Steven A.

    2000-01-01

    Evaluation of redox conditions in groundwater pollution plumes is often a prerequisite for understanding the behaviour of the pollutants in the plume and for selecting remediation approaches. Measuring of redox conditions in pollution plumes is, however, a fairly recent issue and yet relative few...... dubious, if not erroneous. Several other approaches have been used in addressing redox conditions in pollution plumes: redox-sensitive compounds in groundwater samples, hydrogen concentrations in groundwater, concentrations of volatile fatty acids in groundwater, sediment characteristics and microbial...

  19. Discriminative stimulus properties of mitragynine (kratom) in rats.

    Science.gov (United States)

    Harun, Norsyifa; Hassan, Zurina; Navaratnam, Visweswaran; Mansor, Sharif M; Shoaib, Mohammed

    2015-07-01

    Mitragynine (MG) is the primary active alkaloid extracted from the leaves of Mitragyna speciosa or kratom and exhibits pharmacological activities mediated by opioid receptors. The plant has been traditionally used for its opium and psychostimulant-like effects to increase work efficiency or as a substitute in the self-treatment of opiate addiction. The present study was performed to investigate the discriminative stimulus effects of MG in rats. The pharmacological mechanism of MG action and its derivative, 7-hydroxymitragynine (7-HMG) with a specific focus on opioid receptor involvement was examined in rats trained to discriminate morphine from vehicle. In order to study the dual actions of MG, the effect of cocaine substitution to the MG discriminative stimulus was also performed in MG-trained rats. Male Sprague Dawley rats were trained to discriminate MG from vehicle in a two-lever drug discrimination procedure under a tandem variable-interval (VI 60') fixed-ratio (FR 10) schedule of food reinforcement. Rats acquired the MG discrimination (15.0 mg/kg, i.p.) which was similar to the acquisition of morphine discrimination (5.0 mg/kg, i.p.) in another group of rats. MG substituted fully to the morphine discriminative stimulus in a dose-dependent manner, suggesting pharmacological similarities between the two drugs. The administration of 7-HMG derivative in 3.0 mg/kg (i.p.) dose engendered full generalisation to the morphine discriminative stimulus. In addition, the MG stimulus also partially generalised to cocaine (10.0 mg/kg, i.p.) stimulus. The present study demonstrates that the discriminative stimulus effect of MG possesses both opioid- and psychostimulant-like subjective effects.

  20. Redox fluctuations in the Early Ordovician oceans

    DEFF Research Database (Denmark)

    D'Arcy, Joan Mary; Gilleaudeau, Geoffrey Jon; Peralta, Silvio

    2017-01-01

    Chromium (Cr) stable isotopes are a useful tracer of changes in redox conditions because changes in its oxidation state are accompanied by an isotopic fractionation. Recent co-precipitation experiments have shown that Cr(VI) is incorporated into the calcite lattice, suggesting that carbonates are...

  1. Methods for using redox liposome biosensors

    Science.gov (United States)

    Cheng, Quan; Stevens, Raymond C.

    2002-01-01

    The present invention provides methods and compositions for detecting the presence of biologically-important analytes by using redox liposome biosensors. In particular, the present invention provides liposome/sol-gel electrodes suitable for the detection of a wide variety of organic molecules, including but not limited to bacterial toxins.

  2. Le reazioni redox: un pasticcio concettuale?

    Directory of Open Access Journals (Sweden)

    Elena Ghibaudi

    2015-10-01

    Full Text Available Le reazioni di ossidoriduzione costituiscono un argomento centrale di qualsiasi corso di base di chimica, sia a livello scolastico che universitario. Il loro apprendimento comporta il superamento di svariati ostacoli concettuali, la cui difficoltà può risultare amplificata da prassi didattiche inadeguate. Gli errori più ricorrenti nel presentare l’argomento sono di due tipi: i fare implicitamente riferimento a modelli esplicativi distinti (es. il numero di ossidazione e il trasferimento elettronico, senza esplicitarli e senza evidenziarne la differente natura e il campo di validità; ii confondere il livello della spiegazione formale con quello della realtà fisica. I fenomeni redox sono normalmente interpretati sulla base di tre distinti modelli empirici, che fanno riferimento al trasferimento di atomi di ossigeno, di atomi di idrogeno, di elettroni; e di un quarto modello, formale, fondato sul cambiamento del numero di ossidazione. La confusione tra questi modelli può generare considerevoli problemi di apprendimento. Il presente lavoro riporta un’analisi critica delle implicazioni concettuali della didattica dei processi redox. L’analisi è articolata in tre sezioni: i disamina della evoluzione storica del concetto di ossidoriduzione; ii analisi dei modelli redox e del loro campo di validità; iii discussione di alcuni aspetti epistemologici inerenti i processi redox che sono rilevanti per la didattica della chimica.

  3. Quinonoid functionality redox properties Diiminic functionality Lewis ...

    African Journals Online (AJOL)

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    base due to the presence of the two diiminic nitrogen atoms (Scheme 1). Calderazzo et al. [2], showed that PDON reacts with Lewis acids such as TiCl4 to give N,N-coordinated derivatives, and with a low-valent organometallic compound giving a redox reaction (Scheme 2). It has to be noted that when PDON coordinates ...

  4. Immobilization of redox mediators on functionalized carbon ...

    Indian Academy of Sciences (India)

    Chemical functionalization of single-walled carbon nanotubes with redox mediators, namely, toluidine blue and thionin have been carried out and the performance of graphite electrode modified with functionalized carbon nanotubes is described. Mechanical immobilization of functionalized single-walled nanotube (SWNT) ...

  5. Redox characteristics of the eukaryotic cytosol

    DEFF Research Database (Denmark)

    López-Mirabal, H Reynaldo; Winther, Jakob R

    2007-01-01

    organism, Saccharomyces cerevisiae, where the combination of genetic and biochemical approaches has brought us furthest in understanding the mechanisms underlying cellular redox regulation. It has been shown in yeast that, in addition to the enzyme glutathione reductase, other mechanisms may exist...

  6. Metathetical Redox Reaction of (Diacetoxyiodoarenes and Iodoarenes

    Directory of Open Access Journals (Sweden)

    Antoine Jobin-Des Lauriers

    2015-12-01

    Full Text Available The oxidation of iodoarenes is central to the field of hypervalent iodine chemistry. It was found that the metathetical redox reaction between (diacetoxyiodoarenes and iodoarenes is possible in the presence of a catalytic amount of Lewis acid. This discovery opens a new strategy to access (diacetoxyiodoarenes. A computational study is provided to rationalize the results observed.

  7. Investigating improvements on redox flow batteries

    CSIR Research Space (South Africa)

    Swartbooi, AM

    2006-09-01

    Full Text Available storage devices coupled to most of their applications. Lead-acid batteries have long been used as the most economical option to store electricity in many small scale applications, but lately more interest have been shown in redox flow batteries. The low...

  8. Redox regulation in cancer stem cells

    Science.gov (United States)

    Reactive oxygen species (ROS) and ROS-dependent (redox regulation) signaling pathways and transcriptional activities are thought to be critical in stem cell self-renewal and differentiation during growth and organogenesis. Aberrant ROS burst and dysregulation of those ROS-dependent cellular processe...

  9. Redox cycling of potential antitumor aziridinylquinones

    NARCIS (Netherlands)

    Lusthof, Klaas J.; de Mol, Nicolaas J.; Richter, Wilma; Janssen, Lambert H.M.; Butler, John; Hoey, Brigid M.; Verboom, Willem; Reinhoudt, David

    1992-01-01

    The formation of reactive oxygen intermediates (ROI) during redox cycling of newly synthetized potential antitumor 2,5-bis (1-aziridinyl)-1,4-benzoquinone (BABQ) derivatives has been studied by assaying the production of ROI (superoxide, hydroxyl radical, and hydrogen peroxide) by xanthine oxidase

  10. Bimetallic redox synergy in oxidative palladium catalysis.

    Science.gov (United States)

    Powers, David C; Ritter, Tobias

    2012-06-19

    Polynuclear transition metal complexes, which are embedded in the active sites of many metalloenzymes, are responsible for effecting a diverse array of oxidation reactions in nature. The range of chemical transformations remains unparalleled in the laboratory. With few noteworthy exceptions, chemists have primarily focused on mononuclear transition metal complexes in developing homogeneous catalysis. Our group is interested in the development of carbon-heteroatom bond-forming reactions, with a particular focus on identifying reactions that can be applied to the synthesis of complex molecules. In this context, we have hypothesized that bimetallic redox chemistry, in which two metals participate synergistically, may lower the activation barriers to redox transformations relevant to catalysis. In this Account, we discuss redox chemistry of binuclear Pd complexes and examine the role of binuclear intermediates in Pd-catalyzed oxidation reactions. Stoichiometric organometallic studies of the oxidation of binuclear Pd(II) complexes to binuclear Pd(III) complexes and subsequent C-X reductive elimination from the resulting binuclear Pd(III) complexes have confirmed the viability of C-X bond-forming reactions mediated by binuclear Pd(III) complexes. Metal-metal bond formation, which proceeds concurrently with oxidation of binuclear Pd(II) complexes, can lower the activation barrier for oxidation. We also discuss experimental and theoretical work that suggests that C-X reductive elimination is also facilitated by redox cooperation of both metals during reductive elimination. The effect of ligand modification on the structure and reactivity of binuclear Pd(III) complexes will be presented in light of the impact that ligand structure can exert on the structure and reactivity of binuclear Pd(III) complexes. Historically, oxidation reactions similar to those discussed here have been proposed to proceed via mononuclear Pd(IV) intermediates, and the hypothesis of mononuclear Pd

  11. TWO IDEAS OF THE REDOX REACTION: MISCONCEPTIONS AND ...

    African Journals Online (AJOL)

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    participants were not sure about this and chose the reactions ii or iii or both (that are acid-base reactions!), and delivered reasons such as: "MgO and Mg(OH)2 contain oxygen, what is absolutely necessary for redox reactions; to any redox reaction O is necessary – so choice (i) cannot be a redox reaction". These students ...

  12. Are bioassays useful tools to assess redox processes and biodegradation?

    DEFF Research Database (Denmark)

    Albrechtsen, Hans-Jørgen; Pedersen, Philip Grinder; Ludvigsen, L.

    2002-01-01

    sensitive hydrochemical or geochemical parameters, levels of hydrogen, and redox potential. However, all these approaches have to be evaluated against TEAP-bioassays as the most direct measure. We assessed successfully ongoing microbial-mediated redox processes by TEAP-bioassays in degradation studies...... of aromatic and chlorinated aliphatic compounds in landfill leachate plumes, and of pesticides in aquifers with various redox conditions....

  13. Redox Control of Inflammation in Macrophages

    Science.gov (United States)

    Dehne, Nathalie; Grossmann, Nina; Jung, Michaela; Namgaladze, Dmitry; Schmid, Tobias; von Knethen, Andreas; Weigert, Andreas

    2013-01-01

    Abstract Macrophages are present throughout the human body, constitute important immune effector cells, and have variable roles in a great number of pathological, but also physiological, settings. It is apparent that macrophages need to adjust their activation profile toward a steadily changing environment that requires altering their phenotype, a process known as macrophage polarization. Formation of reactive oxygen species (ROS), derived from NADPH-oxidases, mitochondria, or NO-producing enzymes, are not necessarily toxic, but rather compose a network signaling system, known as redox regulation. Formation of redox signals in classically versus alternatively activated macrophages, their action and interaction at the level of key targets, and the resulting physiology still are insufficiently understood. We review the identity, source, and biological activities of ROS produced during macrophage activation, and discuss how they shape the key transcriptional responses evoked by hypoxia-inducible transcription factors, nuclear-erythroid 2-p45-related factor 2 (Nrf2), and peroxisome proliferator-activated receptor-γ. We summarize the mechanisms how redox signals add to the process of macrophage polarization and reprogramming, how this is controlled by the interaction of macrophages with their environment, and addresses the outcome of the polarization process in health and disease. Future studies need to tackle the option whether we can use the knowledge of redox biology in macrophages to shape their mediator profile in pathophysiology, to accelerate healing in injured tissue, to fight the invading pathogens, or to eliminate settings of altered self in tumors. Antioxid. Redox Signal. 19, 595–637. PMID:23311665

  14. The redox stress hypothesis of aging.

    Science.gov (United States)

    Sohal, Rajindar S; Orr, William C

    2012-02-01

    The main objective of this review is to examine the role of endogenous reactive oxygen/nitrogen species (ROS) in the aging process. Until relatively recently, ROS were considered to be potentially toxic by-products of aerobic metabolism, which, if not eliminated, may inflict structural damage on various macromolecules. Accrual of such damage over time was postulated to be responsible for the physiological deterioration in the postreproductive phase of life and eventually the death of the organism. This "structural damage-based oxidative stress" hypothesis has received support from the age-associated increases in the rate of ROS production and the steady-state amounts of oxidized macromolecules; however, there are increasing indications that structural damage alone is insufficient to satisfactorily explain the age-associated functional losses. The level of oxidative damage accrued during aging often does not match the magnitude of functional losses. Although experimental augmentation of antioxidant defenses tends to enhance resistance to induced oxidative stress, such manipulations are generally ineffective in the extension of life span of long-lived strains of animals. More recently, in a major conceptual shift, ROS have been found to be physiologically vital for signal transduction, gene regulation, and redox regulation, among others, implying that their complete elimination would be harmful. An alternative notion, advocated here, termed the "redox stress hypothesis," proposes that aging-associated functional losses are primarily caused by a progressive pro-oxidizing shift in the redox state of the cells, which leads to the overoxidation of redox-sensitive protein thiols and the consequent disruption of the redox-regulated signaling mechanisms. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Stimulus and response chunking in the Hebb Digits task.

    Science.gov (United States)

    O'Shea, Geoffrey; Clegg, Benjamin A

    2006-05-01

    Using the Hebb Digits task, an incidental sequential learning paradigm, the effects of chunking of both the presentation and response phases of performance were examined. In the first experiment, consistent stimulus chunking increased learning, and performance was at an equivalent level to this when consistent chunking of both stimuli and responses was present. Consistent chunking of the responses alone did not significantly improve learning over a baseline condition where neither stimuli nor responses were chunked. The disruption of response organization in a second experiment, through a random response condition, failed to impact learning in non-chunked and stimulus chunked conditions. A third experiment found that response chunking did benefit learning in a condition where stimuli were presented in random chunks. A final experiment suggested extended processing of the digits could not account for performance gains in the stimulus chunking condition. Overall, the results suggest that the enhanced effects of chunking on learning were stimulus-driven rather than response-driven, except under conditions that constrained a consistent pattern of stimulus organization.

  16. Mobile Multicast in Hierarchical Proxy Mobile IPV6

    Science.gov (United States)

    Hafizah Mohd Aman, Azana; Hashim, Aisha Hassan A.; Mustafa, Amin; Abdullah, Khaizuran

    2013-12-01

    Mobile Internet Protocol Version 6 (MIPv6) environments have been developing very rapidly. Many challenges arise with the fast progress of MIPv6 technologies and its environment. Therefore the importance of improving the existing architecture and operations increases. One of the many challenges which need to be addressed is the need for performance improvement to support mobile multicast. Numerous approaches have been proposed to improve mobile multicast performance. This includes Context Transfer Protocol (CXTP), Hierarchical Mobile IPv6 (HMIPv6), Fast Mobile IPv6 (FMIPv6) and Proxy Mobile IPv6 (PMIPv6). This document describes multicast context transfer in hierarchical proxy mobile IPv6 (H-PMIPv6) to provide better multicasting performance in PMIPv6 domain.

  17. How different proxies record precipitation variability over southeastern South America

    Energy Technology Data Exchange (ETDEWEB)

    Chiessi, Cristiano M; Mulitza, Stefan; Paetzold, Juergen; Wefer, Gerold, E-mail: chiessi@uni-bremen.d [MARUM-Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, 28359 Bremen (Germany)

    2010-03-15

    Detrending natural and anthropogenic components of climate variability is arguably an issue of utmost importance to society. To accomplish this issue, one must rely on a comprehensive understanding of the natural variability of the climate system on a regional level. Here we explore how different proxies (e.g., stalagmite oxygen isotopic composition, pollen percentages, bulk sediment elemental ratios) record Holocene precipitation variability over southeastern South America. We found a general good agreement between the different records both on orbital and centennial time-scales. Dry mid Holocene, and wet late Holocene, Younger Dryas and a period between {approx}9.4 and 8.12 cal kyr BP seem to be pervasive features. Moreover, we show that proxy-specific sensitivity can greatly improve past precipitation reconstructions.

  18. A comparison of proxy performance in coral biodiversity monitoring

    Science.gov (United States)

    Richards, Zoe T.

    2013-03-01

    The productivity and health of coral reef habitat is diminishing worldwide; however, the effect that habitat declines have on coral reef biodiversity is not known. Logistical and financial constraints mean that surveys of hard coral communities rarely collect data at the species level; hence it is important to know if there are proxy metrics that can reliably predict biodiversity. Here, the performances of six proxy metrics are compared using regression analyses on survey data from a location in the northern Great Barrier Reef. Results suggest generic richness is a strong explanatory variable for spatial patterns in species richness (explaining 82 % of the variation when measured on a belt transect). The most commonly used metric of reef health, percentage live coral cover, is not positively or linearly related to hard coral species richness. This result raises doubt as to whether management actions based on such reefscape information will be effective for the conservation of coral biodiversity.

  19. False allegations of abuse and Munchausen syndrome by proxy.

    Science.gov (United States)

    Meadow, R

    1993-01-01

    Fourteen children from seven families are reported for whom false allegations of abuse were made by the mother. Twelve children were alleged to have incurred sexual abuse, one both sexual and physical abuse, and one physical abuse alone. Thirteen of the children had incurred, or were currently victims of, factitious illness abuse invented by the mother. The one child with no history of factitious illness abuse had a sibling who had incurred definite factitious illness abuse. The false allegations of abuse did not occur in the context of parental separation, divorce, or custody disputes concerning the children. They occurred in the context of Munchausen syndrome by proxy abuse. The age of the children, 3 to 9 years, was older than the usual age for Munchausen syndrome by proxy abuse. The mother was the source of the false allegations and was the person who encouraged or taught six of the children to substantiate allegations of sexual abuse. PMID:8503664

  20. Munchausen syndrome and Munchausen syndrome by proxy in dermatology.

    Science.gov (United States)

    Boyd, Alan S; Ritchie, Coleman; Likhari, Sunaina

    2014-08-01

    Patients with Munchausen syndrome purposefully injure themselves, often with the injection of foreign materials, to gain hospital admission and the attention associated with having a difficult-to-identify condition. Munchausen syndrome by proxy occurs when a child's caregiver, typically the mother, injures the child for the same reasons. Cases of Munchausen syndrome and Munchausen syndrome by proxy with primary cutaneous involvement appear to be rarely described in the literature suggesting either that diagnosis is not made readily or that it is, in fact, an uncommon disorder. At the center of both conditions is significant psychological pathology and treatment is difficult as many patients with Munchausen syndrome when confronted with these diagnostic possibilities simply leave the hospital. Little is known about the long-term outcome or prognosis of these patients. Copyright © 2014 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

  1. A case report of Factitious Disorder (Munchausen Syndrome by proxy

    Directory of Open Access Journals (Sweden)

    Mehdi Shirzadifar

    2014-09-01

    Full Text Available Background: In Factitious Disorder by proxy, one person (perpetrator induces the disease in another person, thereby seeking emotional needs during the treatment process Diagnosis of this disorder is very difficult and there is not much consensus over it among experts. Lack of timely diagnosis of this disorder may lead to serious harms in patients. Case presentation: We will introduce a 19 year-old boy with mental retardation and history of multiple admissions to psychiatric, internal, urology and surgery wards. He has a 12 year-old sister and a 4 year-old brother, both with history of multiple admissions to pediatrics and internal wards. The father of family was 48 years old with chronic mental disorder, drug dependency and history of multiple admissions to medical, psychiatry and neurology wards. The mother of this family was diagnosed with munchausen syndrome by proxy.

  2. Munchausen syndrome by proxy: an alarming face of child abuse.

    Science.gov (United States)

    Gehlawat, Pratibha; Gehlawat, Virender Kumar; Singh, Priti; Gupta, Rajiv

    2015-01-01

    Munchausen syndrome by proxy (MSBP) is emerging as a serious form of child abuse. It is an intentional production of illness in another, usually children by mothers, to assume sick role by proxy. It is poorly understood and a controversial diagnosis. Treatment is very difficult. We present a case of 9-year-old boy brought to Pt. B. D. Sharma, PGIMS, Rohtak, a tertiary care hospital in northern India by his father and paternal uncle with complaints of hematemesis since July 2012. He underwent many invasive procedures until the diagnosis of MSBP was finally considered. The examination of the blood sample confirmed the diagnosis. The child was placed under custody of his mother. The case was reported to social services, which incorporated whole family in the management.

  3. Unraveling the redox evolution of the Yangtze Block across the Precambrian/Cambrian transition

    Science.gov (United States)

    Diamond, C. W.; Zhang, F.; Chen, Y.; Lyons, T. W.

    2016-12-01

    Rocks preserved on the South China Craton have played a critical role in refining our understanding of the co-evolution of life and Earth's surface environments in the Late Neoproterozoic and earliest Paleozoic. From the earliest metazoan embryos to the many examples of exceptional preservation throughout the Cambrian Explosion, South China has preserved an outstanding record of animal evolution across this critical transition. Similarly, rocks preserved in South China hold key insights into the changing ocean chemistry that accompanied this extraordinary time. Recent work form Sahoo and others (2016, Geobiology) used redox sensitive metal enrichments in the Ediacaran Doushantuo Formation to demonstrate that the redox state of the Latest Neoproterozoic oceans was highly dynamic, rather than stably oxygenated or anoxic as had both been suggested previously. In an attempt to follow on from this and other studies, we have examined samples from a drill core taken in eastern Guizhou capturing deep-water facies of the Liuchapo and Jiumenchong formations, which contain the Precambrian/Cambrian boundary. In addition to containing the boundary, the sampled interval contains an enigmatic, widespread horizon that is strongly enriched in Ni and Mo. We have taken a multi-proxy approach in our investigation of this layer, the possible implications it has for the strata above and below (i.e., how its presence affects their utility as archives of paleo-redox conditions), and what those strata can tell us about local and global redox conditions during this pivotal time in Earth's history. Our Fe speciation data indicate that conditions were sulfidic at this location throughout the majority of the sampled interval. While redox sensitive metal concentrations are dramatically enriched in the Ni/Mo interval, their concentrations return to modest enrichments above it and continue to decrease upward. This trend suggests that while the conditions that favored extreme enrichment during the

  4. Proxy-SU(3) symmetry in heavy deformed nuclei

    Science.gov (United States)

    Bonatsos, Dennis; Assimakis, I. E.; Minkov, N.; Martinou, Andriana; Cakirli, R. B.; Casten, R. F.; Blaum, K.

    2017-06-01

    Background: Microscopic calculations of heavy nuclei face considerable difficulties due to the sizes of the matrices that need to be solved. Various approximation schemes have been invoked, for example by truncating the spaces, imposing seniority limits, or appealing to various symmetry schemes such as pseudo-SU(3). This paper proposes a new symmetry scheme also based on SU(3). This proxy-SU(3) can be applied to well-deformed nuclei, is simple to use, and can yield analytic predictions. Purpose: To present the new scheme and its microscopic motivation, and to test it using a Nilsson model calculation with the original shell model orbits and with the new proxy set. Method: We invoke an approximate, analytic, treatment of the Nilsson model, that allows the above vetting and yet is also transparent in understanding the approximations involved in the new proxy-SU(3). Results: It is found that the new scheme yields a Nilsson diagram for well-deformed nuclei that is very close to the original Nilsson diagram. The specific levels of approximation in the new scheme are also shown, for each major shell. Conclusions: The new proxy-SU(3) scheme is a good approximation to the full set of orbits in a major shell. Being able to replace a complex shell model calculation with a symmetry-based description now opens up the possibility to predict many properties of nuclei analytically and often in a parameter-free way. The new scheme works best for heavier nuclei, precisely where full microscopic calculations are most challenged. Some cases in which the new scheme can be used, often analytically, to make specific predictions, are shown in a subsequent paper.

  5. Law Enforcement Proxies Matter for the Law and Finance Nexus

    OpenAIRE

    Valentin Toci; Iraj Hashi

    2013-01-01

    The paper employs various measures of law enforcement to provide new evidence on the importance of legal institutions for different dimensions of financial development in transition economies. It offers a critical assessment of law enforcement measures employed in recent studies by showing that some proxies for law enforcement in the credit market may not be appropriate. Hence, care should be taken in how the quality of institutions is measured and the context which it represents. An original...

  6. Fingerprinting Reverse Proxies Using Timing Analysis of TCP Flows

    Science.gov (United States)

    2013-09-01

    Address Translation NPS Naval Postgraduate School OTT One-way Transit Time PET Privacy Enhancing Technology PHP Hypertext Preprocessor P2P ] Peer-to...of timing information that can translate into usable intelligence for detecting the use of reverse proxies by a network domain. 1.1 Problem Statement...websites (i.e., Sky News Arabia, Kemalist Gazete, Detroit News), and entertainment industry sites (i.e., HBO GO, LeoVegas Online Casino , FreeRide Games

  7. Widespread ability of fungi to drive quinone redox cycling for biodegradation.

    Science.gov (United States)

    Krueger, Martin C; Bergmann, Michael; Schlosser, Dietmar

    2016-06-01

    Wood-rotting fungi possess remarkably diverse extracellular oxidation mechanisms, including enzymes, such as laccase and peroxidases, and Fenton chemistry. The ability to biologically drive Fenton chemistry by the redox cycling of quinones has previously been reported to be present in both ecologically diverging main groups of wood-rotting basidiomycetes. Therefore, we investigated whether it is even more widespread among fungal organisms. Screening of a diverse selection of a total of 18 ascomycetes and basidiomycetes for reduction of the model compound 2,6-dimethoxy benzoquinone revealed that all investigated strains were capable of reducing it to its corresponding hydroquinone. In a second step, depolymerization of the synthetic polymer polystyrene sulfonate was used as a proxy for quinone-dependent Fenton-based biodegradation capabilities. A diverse subset of the strains, including environmentally ubiquitous molds, white-rot fungi, as well as peatland and aquatic isolates, caused substantial depolymerization indicative for the effective employment of quinone redox cycling as biodegradation tool. Our results may also open up new paths to utilize diverse fungi for the bioremediation of recalcitrant organic pollutants. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  8. Marine proxy evidence linking decadal North Pacific and Atlantic climate

    Energy Technology Data Exchange (ETDEWEB)

    Hetzinger, S. [University of Toronto Mississauga, CPS-Department, Mississauga, ON (Canada); Leibniz Institute of Marine Sciences, IFM-GEOMAR, Kiel (Germany); Halfar, J. [University of Toronto Mississauga, CPS-Department, Mississauga, ON (Canada); Mecking, J.V.; Keenlyside, N.S. [Leibniz Institute of Marine Sciences, IFM-GEOMAR, Kiel (Germany); University of Bergen, Geophysical Institute and Bjerknes Centre for Climate Research, Bergen (Norway); Kronz, A. [University of Goettingen, Geowissenschaftliches Zentrum, Goettingen (Germany); Steneck, R.S. [University of Maine, Darling Marine Center, Walpole, ME (United States); Adey, W.H. [Smithsonian Institution, Department of Botany, Washington, DC (United States); Lebednik, P.A. [ARCADIS U.S. Inc., Walnut Creek, CA (United States)

    2012-09-15

    Decadal- to multidecadal variability in the extra-tropical North Pacific is evident in 20th century instrumental records and has significant impacts on Northern Hemisphere climate and marine ecosystems. Several studies have discussed a potential linkage between North Pacific and Atlantic climate on various time scales. On decadal time scales no relationship could be confirmed, potentially due to sparse instrumental observations before 1950. Proxy data are limited and no multi-centennial high-resolution marine geochemical proxy records are available from the subarctic North Pacific. Here we present an annually-resolved record (1818-1967) of Mg/Ca variations from a North Pacific/Bering Sea coralline alga that extends our knowledge in this region beyond available data. It shows for the first time a statistically significant link between decadal fluctuations in sea-level pressure in the North Pacific and North Atlantic. The record is a lagged proxy for decadal-scale variations of the Aleutian Low. It is significantly related to regional sea surface temperature and the North Atlantic Oscillation (NAO) index in late boreal winter on these time scales. Our data show that on decadal time scales a weaker Aleutian Low precedes a negative NAO by several years. This atmospheric link can explain the coherence of decadal North Pacific and Atlantic Multidecadal Variability, as suggested by earlier studies using climate models and limited instrumental data. (orig.)

  9. MUNCHAUSEN SYNDROME BY PROXY IN PEDIATRIC DENTISTRY: MYTH OR REALITY?

    Directory of Open Access Journals (Sweden)

    Veronica PINTILICIUC-ŞERBAN

    2017-06-01

    Full Text Available Background and aims: Munchausen syndrome by proxy is a condition traditionally comprising physical and mental abuse and medical neglect as a form of psychogenic maltreatment of the child, secondary to fabrication of a pediatric illness by the parent or guardian. The aim of our paper is to assess whether such condition occurs in current pediatric dental practice and to evidence certain situations in which the pediatric dentist should suspect this form of child abuse. Problem statement: Munchausen syndrome by proxy in pediatric dentistry may lead to serious chronic disabilities of the abused or neglected child, being one of the causes of treatment failure. Discussion: Prompt detection of such condition should be regarded as one of the duties of the practitioner who should be trained to report the suspected cases to the governmental child protective agencies. This should be regarded as a form of child abuse and neglect, and the responsible caregiver could be held liable when such wrongful actions cause harm or endanger child’s welfare. Conclusion: Munchausen syndrome by proxy should be regarded as a reality in current pediatric dental practice and dental teams should be trained to properly recognize, assess and manage such complex situations.

  10. Short-term indicators. Intensities as a proxy for savings

    Energy Technology Data Exchange (ETDEWEB)

    Boonekamp, P.G.M.; Gerdes, J. [ECN Policy Studies, Petten (Netherlands); Faberi, S. [Institute of Studies for the Integration of Systems ISIS, Rome (Italy)

    2013-12-15

    The ODYSSEE database on energy efficiency indicators (www.odyssee-indicators.org) has been set up to enable the monitoring and evaluation of realised energy efficiency improvements and related energy savings. The database covers the 27 EU countries as well as Norway and Croatia and data are available from 1990 on. This work contributes to the growing need for quantitative monitoring and evaluation of the impacts of energy policies and measures, both at the EU and national level, e.g. due to the Energy Services Directive and the proposed Energy Efficiency Directive. Because the underlying data become available only after some time, the savings figures are not always timely available. This is especially true for the ODEX efficiency indices per sector that rely on a number of indicators. Therefore, there is a need for so-called short-term indicators that become available shortly after the year has passed for which data are needed. The short term indicators do not replace the savings indicators but function as a proxy for the savings in the most recent year. This proxy value is faster available, but will be less accurate than the saving indicators themselves. The short term indicators have to be checked regularly with the ODEX indicators in order to see whether they can function still as a proxy.

  11. A unified proxy for ENSO and PDO variability since 1650

    Directory of Open Access Journals (Sweden)

    S. McGregor

    2010-01-01

    Full Text Available In this manuscript we have attempted to consolidate the common signal in previously defined proxy reconstructions of the El Niño-Southern Oscillation into one individual proxy titled the Unified ENSO Proxy (UEP. While correlating well with the majority of input reconstructions, the UEP provides better representation of observed indices of ENSO, discrete ENSO events and documented historical chronologies of ENSO than any of these input ENSO reconstructions. Further to this, the UEP also provides a means to reconstruct the PDO/IPO multi-decadal variability of the Pacific Ocean as the low-pass filtered UEP displays multi-decadal variability that is consistent with the 20th century variability of the PDO and IPO. The UEP is then used to describe changes in ENSO variability which have occurred since 1650 focusing on changes in ENSOs variance, multi-year ENSO events, PDO-like multi-decadal variability and the effects of volcanic and solar forcing on ENSO. We find that multi-year El Niño events similar to the 1990–1995 event have occurred several times over the last 3 1/2 centuries. Consistent with earlier studies we find that volcanic forcing can induce a statistically significant change in the mean state of ENSO in the year of the eruption and a doubling of the probability of an El Niño (La Niña event occurring in the year of (three years after the eruption.

  12. Evaluating Ground-based Proxies for Solar Irradiance Variation

    Science.gov (United States)

    Oegerle, William (Technical Monitor); Jordan, Stuart

    2003-01-01

    In order to determine what ground-based proxies are best for evaluating solar irradiance variation before the advent of space observations, it is necessary to test these proxies against space observations. We have tested sunspot number, total sunspot area, and sunspot umbral area against the Nimbus-7 measurements of total solar irradiance variation cover the eleven year period 1980-1990. The umbral area yields the best correlation and the total sunspot area yields the poorest. Reasons for expecting the umbral area to yield the best correlation are given, the statistical procedure followed to obtain the results is described, and the value of determining the best proxy is discussed. The latter is based upon the availability of an excellent database from the Greenwich Observatory obtained over the period 1876-1976, which can be used to estimate the total solar irradiance variation before sensitive space observations were available. The ground-based observations used were obtained at the Coimbra Solar Observatory. The analysis was done at Goddard using these data and data from the Nimbus-7 satellite.

  13. Shell architecture: a novel proxy for paleotemperature reconstructions?

    Science.gov (United States)

    Milano, Stefania; Nehrke, Gernot; Wanamaker, Alan D., Jr.; Witbaard, Rob; Schöne, Bernd R.

    2017-04-01

    Mollusk shells are unique high-resolution paleoenvironmental archives. Their geochemical properties, such as oxygen isotope composition (δ18Oshell) and element-to-calcium ratios, are routinely used to estimate past environmental conditions. However, the existing proxies have certain drawbacks that can affect paleoreconstruction robustness. For instance, the estimation of water temperature of brackish and near-shore environments can be biased by the interdependency of δ18Oshell from multiple environmental variables (water temperature and δ18Owater). Likely, the environmental signature can be masked by physiological processes responsible for the incorporation of trace elements into the shell. The present study evaluated the use of shell structural properties as alternative environmental proxies. The sensitivity of shell architecture at µm and nm-scale to the environment was tested. In particular, the relationship between water temperature and microstructure formation was investigated. To enable the detection of potential structural changes, the shells of the marine bivalves Cerastoderma edule and Arctica islandica were analyzed with Scanning Electron Microscopy (SEM), nanoindentation and Confocal Raman Microscopy (CRM). These techniques allow a quantitative approach to the microstructural analysis. Our results show that water temperature induces a clear response in shell microstructure. A significant alteration in the morphometric characteristics and crystallographic orientation of the structural units was observed. Our pilot study suggests that shell architecture records environmental information and it has potential to be used as novel temperature proxy in near-shore and open ocean habitats.

  14. Heinrich event 4 characterized by terrestrial proxies in southwestern Europe

    Directory of Open Access Journals (Sweden)

    J. M. López-García

    2013-05-01

    Full Text Available Heinrich event 4 (H4 is well documented in the North Atlantic Ocean as a cooling event that occurred between 39 and 40 Ka. Deep-sea cores around the Iberian Peninsula coastline have been analysed to characterize the H4 event, but there are no data on the terrestrial response to this event. Here we present for the first time an analysis of terrestrial proxies for characterizing the H4 event, using the small-vertebrate assemblage (comprising small mammals, squamates and amphibians from Terrassa Riera dels Canyars, an archaeo-palaeontological deposit located on the seaboard of the northeastern Iberian Peninsula. This assemblage shows that the H4 event is characterized in northeastern Iberia by harsher and drier terrestrial conditions than today. Our results were compared with other proxies such as pollen, charcoal, phytolith, avifauna and large-mammal data available for this site, as well as with the general H4 event fluctuations and with other sites where H4 and the previous and subsequent Heinrich events (H5 and H3 have been detected in the Mediterranean and Atlantic regions of the Iberian Peninsula. We conclude that the terrestrial proxies follow the same patterns as the climatic and environmental conditions detected by the deep-sea cores at the Iberian margins.

  15. Error characterization for asynchronous computations: Proxy equation approach

    Science.gov (United States)

    Sallai, Gabriella; Mittal, Ankita; Girimaji, Sharath

    2017-11-01

    Numerical techniques for asynchronous fluid flow simulations are currently under development to enable efficient utilization of massively parallel computers. These numerical approaches attempt to accurately solve time evolution of transport equations using spatial information at different time levels. The truncation error of asynchronous methods can be divided into two parts: delay dependent (EA) or asynchronous error and delay independent (ES) or synchronous error. The focus of this study is a specific asynchronous error mitigation technique called proxy-equation approach. The aim of this study is to examine these errors as a function of the characteristic wavelength of the solution. Mitigation of asynchronous effects requires that the asynchronous error be smaller than synchronous truncation error. For a simple convection-diffusion equation, proxy-equation error analysis identifies critical initial wave-number, λc. At smaller wave numbers, synchronous error are larger than asynchronous errors. We examine various approaches to increase the value of λc in order to improve the range of applicability of proxy-equation approach.

  16. Implicit sequence learning is represented by stimulus-response rules.

    Science.gov (United States)

    Schwarb, Hillary; Schumacher, Eric H

    2010-09-01

    For nearly two decades, researchers have investigated spatial sequence learning in an attempt to identify what specifically is learned during sequential tasks (e.g., stimulus order, response order, etc.). Despite extensive research, controversy remains concerning the information-processing locus of this learning effect. There are three main theories concerning the nature of spatial sequence learning, corresponding to the perceptual, motor, or response selection (i.e., central mechanisms underlying the association between stimulus and response pairs) processes required for successful task performance. The present data investigate this controversy and support the theory that stimulus-response (S-R) rules are critical for sequence learning. The results from two experiments demonstrate that sequence learning is disrupted only when the S-R rules for the task are altered. When the S-R rules remain constant or involve only a minor transformation, significant sequence learning occurs. These data implicate spatial response selection as a likely mechanism mediating spatial sequential learning.

  17. Cognitive versus stimulus-response theories of learning.

    Science.gov (United States)

    Holland, Peter C

    2008-08-01

    In his 1948 address to the Division of Theoretical-Experimental Psychology of the American Psychological Association, Kenneth W. Spence discussed six distinctions between cognitive and stimulus-response (S-R) theories of learning. In this article, I first review these six distinctions and then focus on two of them in the context of my own research. This research concerns the specification of stimulus-stimulus associations in associative learning and the characterization of the neural systems underlying those associations. In the course of describing Spence's views and my research, I hope to communicate some of the richness of Spence's S-R psychology and its currency within modern scientific analyses of behavior.

  18. Stimulus-dependent effects on tactile spatial acuity

    Directory of Open Access Journals (Sweden)

    Tommerdahl M

    2005-10-01

    Full Text Available Abstract Background Previous studies have shown that spatio-tactile acuity is influenced by the clarity of the cortical response in primary somatosensory cortex (SI. Stimulus characteristics such as frequency, amplitude, and location of tactile stimuli presented to the skin have been shown to have a significant effect on the response in SI. The present study observes the effect of changing stimulus parameters of 25 Hz sinusoidal vertical skin displacement stimulation ("flutter" on a human subject's ability to discriminate between two adjacent or near-adjacent skin sites. Based on results obtained from recent neurophysiological studies of the SI response to different conditions of vibrotactile stimulation, we predicted that the addition of 200 Hz vibration to the same site that a two-point flutter stimulus was delivered on the skin would improve a subject's spatio-tactile acuity over that measured with flutter alone. Additionally, similar neurophysiological studies predict that the presence of either a 25 Hz flutter or 200 Hz vibration stimulus on the unattended hand (on the opposite side of the body from the site of two-point limen testing – the condition of bilateral stimulation – which has been shown to evoke less SI cortical activity than the contralateral-only stimulus condition would decrease a subject's ability to discriminate between two points on the skin. Results A Bekesy tracking method was employed to track a subject's ability to discriminate between two-point stimuli delivered to the skin. The distance between the two points of stimulation was varied on a trial-by-trial basis, and several different stimulus conditions were examined: (1 The "control" condition, in which 25 Hz flutter stimuli were delivered simultaneously to the two points on the skin of the attended hand, (2 the "complex" condition, in which a combination of 25 Hz flutter and 200 Hz vibration stimuli were delivered to the two points on the attended hand, and (3 a

  19. Saccadic modulation of stimulus processing in primary visual cortex

    Science.gov (United States)

    McFarland, James M.; Bondy, Adrian G.; Saunders, Richard C.; Cumming, Bruce G.; Butts, Daniel A.

    2015-01-01

    Saccadic eye movements play a central role in primate vision. Yet, relatively little is known about their effects on the neural processing of visual inputs. Here we examine this question in primary visual cortex (V1) using receptive-field-based models, combined with an experimental design that leaves the retinal stimulus unaffected by saccades. This approach allows us to analyse V1 stimulus processing during saccades with unprecedented detail, revealing robust perisaccadic modulation. In particular, saccades produce biphasic firing rate changes that are composed of divisive gain suppression followed by an additive rate increase. Microsaccades produce similar, though smaller, modulations. We furthermore demonstrate that this modulation is likely inherited from the LGN, and is driven largely by extra-retinal signals. These results establish a foundation for integrating saccades into existing models of visual cortical stimulus processing, and highlight the importance of studying visual neuron function in the context of eye movements. PMID:26370359

  20. Efficient Conditional Proxy Re-encryption with Chosen-Ciphertext Security

    NARCIS (Netherlands)

    Weng, Jiang; Yang, Yanjiang; Tang, Qiang; Deng, Robert H.; Bao, Feng

    Recently, a variant of proxy re-encryption, named conditional proxy re-encryption (C-PRE), has been introduced. Compared with traditional proxy re-encryption, C-PRE enables the delegator to implement fine-grained delegation of decryption rights, and thus is more useful in many applications. In this

  1. 17 CFR 240.14a-16 - Internet availability of proxy materials.

    Science.gov (United States)

    2010-04-01

    ... holder to access and review the proxy materials before voting; (3) The Internet Web site address where... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Internet availability of proxy... Under the Securities Exchange Act of 1934 Regulation 14a: Solicitation of Proxies § 240.14a-16 Internet...

  2. Remote Patron Validation: Posting a Proxy Server at the Digital Doorway.

    Science.gov (United States)

    Webster, Peter

    2002-01-01

    Discussion of remote access to library services focuses on proxy servers as a method for remote access, based on experiences at Saint Mary's University (Halifax). Topics include Internet protocol user validation; browser-directed proxies; server software proxies; vendor alternatives for validating remote users; and Internet security issues. (LRW)

  3. A novel salinity proxy based on Na incorporation into foraminiferal calcite

    NARCIS (Netherlands)

    Wit, J.C.; de Nooijer, L.J.; Wolthers, M.; Reichart, G.J.

    2013-01-01

    Salinity and temperature determine seawater density, and differences in both thereby control global thermohaline circulation. Whereas numerous proxies have been calibrated and applied to reconstruct temperature, a direct and independent proxy for salinity is still missing. Ideally, a new proxy for

  4. A Type-and-Identity-based Proxy Re-Encryption Scheme and its Application in Healthcare

    NARCIS (Netherlands)

    Ibraimi, L.; Tang, Qiang; Hartel, Pieter H.; Jonker, Willem

    2008-01-01

    Proxy re-encryption is a cryptographic primitive developed to delegate the decryption right from one party (the delegator) to another (the delegatee). In a proxy re-encryption scheme, the delegator assigns a key to a proxy to re-encrypt all messages encrypted with his public key such that the

  5. StimDuino: an Arduino-based electrophysiological stimulus isolator.

    Science.gov (United States)

    Sheinin, Anton; Lavi, Ayal; Michaelevski, Izhak

    2015-03-30

    Electrical stimulus isolator is a widely used device in electrophysiology. The timing of the stimulus application is usually automated and controlled by the external device or acquisition software; however, the intensity of the stimulus is adjusted manually. Inaccuracy, lack of reproducibility and no automation of the experimental protocol are disadvantages of the manual adjustment. To overcome these shortcomings, we developed StimDuino, an inexpensive Arduino-controlled stimulus isolator allowing highly accurate, reproducible automated setting of the stimulation current. The intensity of the stimulation current delivered by StimDuino is controlled by Arduino, an open-source microcontroller development platform. The automatic stimulation patterns are software-controlled and the parameters are set from Matlab-coded simple, intuitive and user-friendly graphical user interface. The software also allows remote control of the device over the network. Electrical current measurements showed that StimDuino produces the requested current output with high accuracy. In both hippocampal slice and in vivo recordings, the fEPSP measurements obtained with StimDuino and the commercial stimulus isolators showed high correlation. Commercial stimulus isolators are manually managed, while StimDuino generates automatic stimulation patterns with increasing current intensity. The pattern is utilized for the input-output relationship analysis, necessary for assessment of excitability. In contrast to StimuDuino, not all commercial devices are capable for remote control of the parameters and stimulation process. StimDuino-generated automation of the input-output relationship assessment eliminates need for the current intensity manually adjusting, improves stimulation reproducibility, accuracy and allows on-site and remote control of the stimulation parameters. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Mesoporous tungsten oxynitride as electrocatalyst for promoting redox reactions of vanadium redox couple and performance of vanadium redox flow battery

    Science.gov (United States)

    Lee, Wonmi; Jo, Changshin; Youk, Sol; Shin, Hun Yong; Lee, Jinwoo; Chung, Yongjin; Kwon, Yongchai

    2018-01-01

    For enhancing the performance of vanadium redox flow battery (VRFB), a sluggish reaction rate issue of V2+/V3+ redox couple evaluated as the rate determining reaction should be addressed. For doing that, mesoporous tungsten oxide (m-WO3) and oxyniride (m-WON) structures are proposed as the novel catalysts, while m-WON is gained by NH3 heat treatment of m-WO3. Their specific surface area, crystal structure, surface morphology and component analysis are measured using BET, XRD, TEM and XPS, while their catalytic activity for V2+/V3+ redox reaction is electrochemically examined. As a result, the m-WON shows higher peak current, smaller peak potential difference, higher electron transfer rate constant and lower charge transfer resistance than other catalysts, like the m-WO3, WO3 nanoparticle and mesoporous carbon, proving that it is superior catalyst. Regarding the charge-discharge curve tests, the VRFB single cell employing the m-WON demonstrates high voltage and energy efficiencies, high specific capacity and low capacity loss rate. The excellent results of m-WON are due to the reasons like (i) reduced energy band gap, (ii) reaction familiar surface functional groups and (ii) greater electronegativity.

  7. Cooperative redox activation for carbon dioxide conversion.

    Science.gov (United States)

    Lian, Zhong; Nielsen, Dennis U; Lindhardt, Anders T; Daasbjerg, Kim; Skrydstrup, Troels

    2016-12-16

    A longstanding challenge in production chemistry is the development of catalytic methods for the transformation of carbon dioxide into useful chemicals. Silane and borane promoted reductions can be fined-tuned to provide a number of C1-building blocks under mild conditions, but these approaches are limited because of the production of stoichiometric waste compounds. Here we report on the conversion of CO2 with diaryldisilanes, which through cooperative redox activation generate carbon monoxide and a diaryldisiloxane that actively participate in a palladium-catalysed carbonylative Hiyama-Denmark coupling for the synthesis of an array of pharmaceutically relevant diarylketones. Thus the disilane reagent not only serves as the oxygen abstracting agent from CO2, but the silicon-containing 'waste', produced through oxygen insertion into the Si-Si bond, participates as a reagent for the transmetalation step in the carbonylative coupling. Hence this concept of cooperative redox activation opens up for new avenues in the conversion of CO2.

  8. Cooperative redox activation for carbon dioxide conversion

    Science.gov (United States)

    Lian, Zhong; Nielsen, Dennis U.; Lindhardt, Anders T.; Daasbjerg, Kim; Skrydstrup, Troels

    2016-12-01

    A longstanding challenge in production chemistry is the development of catalytic methods for the transformation of carbon dioxide into useful chemicals. Silane and borane promoted reductions can be fined-tuned to provide a number of C1-building blocks under mild conditions, but these approaches are limited because of the production of stoichiometric waste compounds. Here we report on the conversion of CO2 with diaryldisilanes, which through cooperative redox activation generate carbon monoxide and a diaryldisiloxane that actively participate in a palladium-catalysed carbonylative Hiyama-Denmark coupling for the synthesis of an array of pharmaceutically relevant diarylketones. Thus the disilane reagent not only serves as the oxygen abstracting agent from CO2, but the silicon-containing `waste', produced through oxygen insertion into the Si-Si bond, participates as a reagent for the transmetalation step in the carbonylative coupling. Hence this concept of cooperative redox activation opens up for new avenues in the conversion of CO2.

  9. Anion permselective membrane. [For redox fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, S.S.; Hodgdon, R.B.

    1978-01-01

    Experimental anion permeselective membranes were improved and characterized for use as separators in a chemical redox, power storage cell being developed at the NASA Lewis Research Center. The goal of minimal Fe/sup +3/ ion transfer was achieved for each candidate membrane system. Minimal membrane resistivity was demonstrated by reduction of film thickness using synthetic backing materials but usefulness of thin membranes was limited by the scarcity of compatible fabrics. The most durable and useful backing fabrics were modacrylics. One membrane, a copolymer of 4 vinylpyridine and vinyl benzylchloride was outstanding in overall electrochemical and physical properties. Long term (1000 hrs) membrane chemical and thermal durability in redox environment was shown by three candidate polymers and two membranes. The remainder had good durability at ambient temperature. Manufacturing capability was demonstrated for large scale production of membrane sheets 5.5 ft/sup 2/ in area for two candidate systems.

  10. Cross-modal stimulus conflict: the behavioral effects of stimulus input timing in a visual-auditory Stroop task.

    Science.gov (United States)

    Donohue, Sarah E; Appelbaum, Lawrence G; Park, Christina J; Roberts, Kenneth C; Woldorff, Marty G

    2013-01-01

    Cross-modal processing depends strongly on the compatibility between different sensory inputs, the relative timing of their arrival to brain processing components, and on how attention is allocated. In this behavioral study, we employed a cross-modal audio-visual Stroop task in which we manipulated the within-trial stimulus-onset-asynchronies (SOAs) of the stimulus-component inputs, the grouping of the SOAs (blocked vs. random), the attended modality (auditory or visual), and the congruency of the Stroop color-word stimuli (congruent, incongruent, neutral) to assess how these factors interact within a multisensory context. One main result was that visual distractors produced larger incongruency effects on auditory targets than vice versa. Moreover, as revealed by both overall shorter response times (RTs) and relative shifts in the psychometric incongruency-effect functions, visual-information processing was faster and produced stronger and longer-lasting incongruency effects than did auditory. When attending to either modality, stimulus incongruency from the other modality interacted with SOA, yielding larger effects when the irrelevant distractor occurred prior to the attended target, but no interaction with SOA grouping. Finally, relative to neutral-stimuli, and across the wide range of the SOAs employed, congruency led to substantially more behavioral facilitation than did incongruency to interference, in contrast to findings that within-modality stimulus-compatibility effects tend to be more evenly split between facilitation and interference. In sum, the present findings reveal several key characteristics of how we process the stimulus compatibility of cross-modal sensory inputs, reflecting stimulus processing patterns that are critical for successfully navigating our complex multisensory world.

  11. Cross-modal stimulus conflict: the behavioral effects of stimulus input timing in a visual-auditory Stroop task.

    Directory of Open Access Journals (Sweden)

    Sarah E Donohue

    Full Text Available Cross-modal processing depends strongly on the compatibility between different sensory inputs, the relative timing of their arrival to brain processing components, and on how attention is allocated. In this behavioral study, we employed a cross-modal audio-visual Stroop task in which we manipulated the within-trial stimulus-onset-asynchronies (SOAs of the stimulus-component inputs, the grouping of the SOAs (blocked vs. random, the attended modality (auditory or visual, and the congruency of the Stroop color-word stimuli (congruent, incongruent, neutral to assess how these factors interact within a multisensory context. One main result was that visual distractors produced larger incongruency effects on auditory targets than vice versa. Moreover, as revealed by both overall shorter response times (RTs and relative shifts in the psychometric incongruency-effect functions, visual-information processing was faster and produced stronger and longer-lasting incongruency effects than did auditory. When attending to either modality, stimulus incongruency from the other modality interacted with SOA, yielding larger effects when the irrelevant distractor occurred prior to the attended target, but no interaction with SOA grouping. Finally, relative to neutral-stimuli, and across the wide range of the SOAs employed, congruency led to substantially more behavioral facilitation than did incongruency to interference, in contrast to findings that within-modality stimulus-compatibility effects tend to be more evenly split between facilitation and interference. In sum, the present findings reveal several key characteristics of how we process the stimulus compatibility of cross-modal sensory inputs, reflecting stimulus processing patterns that are critical for successfully navigating our complex multisensory world.

  12. Proterozoic ocean redox and biogeochemical stasis.

    Science.gov (United States)

    Reinhard, Christopher T; Planavsky, Noah J; Robbins, Leslie J; Partin, Camille A; Gill, Benjamin C; Lalonde, Stefan V; Bekker, Andrey; Konhauser, Kurt O; Lyons, Timothy W

    2013-04-02

    The partial pressure of oxygen in Earth's atmosphere has increased dramatically through time, and this increase is thought to have occurred in two rapid steps at both ends of the Proterozoic Eon (∼2.5-0.543 Ga). However, the trajectory and mechanisms of Earth's oxygenation are still poorly constrained, and little is known regarding attendant changes in ocean ventilation and seafloor redox. We have a particularly poor understanding of ocean chemistry during the mid-Proterozoic (∼1.8-0.8 Ga). Given the coupling between redox-sensitive trace element cycles and planktonic productivity, various models for mid-Proterozoic ocean chemistry imply different effects on the biogeochemical cycling of major and trace nutrients, with potential ecological constraints on emerging eukaryotic life. Here, we exploit the differing redox behavior of molybdenum and chromium to provide constraints on seafloor redox evolution by coupling a large database of sedimentary metal enrichments to a mass balance model that includes spatially variant metal burial rates. We find that the metal enrichment record implies a Proterozoic deep ocean characterized by pervasive anoxia relative to the Phanerozoic (at least ∼30-40% of modern seafloor area) but a relatively small extent of euxinic (anoxic and sulfidic) seafloor (less than ∼1-10% of modern seafloor area). Our model suggests that the oceanic Mo reservoir is extremely sensitive to perturbations in the extent of sulfidic seafloor and that the record of Mo and chromium enrichments through time is consistent with the possibility of a Mo-N colimited marine biosphere during many periods of Earth's history.

  13. Redox Flow Batteries, Hydrogen and Distributed Storage

    OpenAIRE

    Dennison, C. R.; Vrubel, Heron; Amstutz, Véronique; Peljo, Pekka Eero; Toghill, Kathryn E.; GIRAULT Hubert

    2015-01-01

    Social, economic, and political pressures are causing a shift in the global energy mix, with a preference toward renewable energy sources. In order to realize widespread implementation of these resources, large-scale storage of renewable energy is needed. Among the proposed energy storage technologies, redox flow batteries offer many unique advantages. The primary limitation of these systems, however, is their limited energy density which necessitates very large installations. In order to enh...

  14. Redox signalling and cardioprotection: translatability and mechanism.

    Science.gov (United States)

    Pagliaro, P; Penna, C

    2015-04-01

    The morbidity and mortality from coronary artery disease (CAD) remain significant worldwide. The treatment for acute myocardial infarction has improved over the past decades, including early reperfusion of culprit coronary arteries. Although it is mandatory to reperfuse the ischaemic territory as soon as possible, paradoxically this leads to additional myocardial injury, namely ischaemia/reperfusion (I/R) injury, in which redox stress plays a pivotal role and for which no effective therapy is currently available. In this review, we report evidence that the redox environment plays a pivotal role not only in I/R injury but also in cardioprotection. In fact, cardioprotective strategies, such as pre- and post-conditioning, result in a robust reduction in infarct size in animals and the role of redox signalling is of paramount importance in these conditioning strategies. Nitrosative signalling and cysteine redox modifications, such as S-nitrosation/S-nitrosylation, are also emerging as very important mechanisms in conditioning cardioprotection. The reasons for the switch from protective oxidative/nitrosative signalling to deleterious oxidative/nitrosative/nitrative stress are not fully understood. The complex regulation of this switch is, at least in part, responsible for the diminished or lack of cardioprotection induced by conditioning protocols observed in ageing animals and with co-morbidities as well as in humans. Therefore, it is important to understand at a mechanistic level the reasons for these differences before proposing a safe and useful transition of ischaemic or pharmacological conditioning. Indeed, more mechanistic novel therapeutic strategies are required to protect the heart from I/R injury and to improve clinical outcomes in patients with CAD. © 2014 The British Pharmacological Society.

  15. Unidirectional redox-stimulated movement around a C-C single bond.

    Science.gov (United States)

    Tepper, Christina; Haberhauer, Gebhard

    2011-07-11

    A remarkable challenge for the design of molecular machines is the realization of a synchronized and unidirectional movement caused by an external stimulus. Such a movement can be achieved by a unidirectionally controlled change of the conformation or the configuration. Biphenol derivatives are one possibility to realize a redox-driven unidirectional molecular switch. For this reason, a 4,4'-biphenol derivative was fixed to a chiral cyclopeptidic scaffold and stimulated by chemical oxidants and reduction agents. The conformation of the switch was determined by DFT calculations by using B3LYP and the 6-31G* basis set. The switching process was observed by UV and circular dichroism (CD) spectroscopic measurements. Several oxidation agents and various conditions were tested, among which (diacetoxy)iodobenzene (DAIB) in methanol proved to be the best. In this way it was possible to synthesize a redox-stimulated molecular switch with a movement that is part of a rotation around a biaryl binding axis. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Redox equilibria of iron oxides in aqueous-based magnetite dispersions: effect of pH and redox potential.

    Science.gov (United States)

    Pang, Suh Cem; Chin, Suk Fun; Anderson, Marc A

    2007-07-01

    The effect of pH and redox potential on the redox equilibria of iron oxides in aqueous-based magnetite dispersions was investigated. The ionic activities of each dissolved iron species in equilibrium with magnetite nanoparticles were determined and contoured within the Eh-pH framework of a composite stability diagram. Both standard redox potentials and equilibrium constants for all major iron oxide redox equilibria in magnetite dispersions were found to differ from values reported for noncolloidal systems. The "triple point" position of redox equilibrium among Fe(II) ions, magnetite, and hematite shifted to a higher standard redox potential and an equilibrium constant which was several orders of magnitude higher. The predominant area of magnetite stability was enlarged to cover a wider range of both pH and redox potentials as compared to that of a noncolloidal magnetite system.

  17. Reactive oxygen species and redox compartmentalization

    Directory of Open Access Journals (Sweden)

    Nina eKaludercic

    2014-08-01

    Full Text Available Reactive oxygen species (ROS formation and signaling are of major importance and regulate a number of processes in physiological conditions. A disruption in redox status regulation, however, has been associated with numerous pathological conditions. In recent years it has become increasingly clear that oxidative and reductive modifications are confined in a spatiotemporal manner. This makes ROS signaling similar to that of Ca2+ or other second messengers. Some subcellular compartments are more oxidizing (such as lysosomes or peroxisomes whereas others are more reducing (mitochondria, nuclei. Moreover, although more reducing, mitochondria are especially susceptible to oxidation, most likely due to the high number of exposed thiols present in that compartment. Recent advances in the development of redox probes allow specific measurement of defined ROS in different cellular compartments in intact living cells or organisms. The availability of these tools now allows simultaneous spatiotemporal measurements and correlation between ROS generation and organelle and/or cellular function. The study of ROS compartmentalization and microdomains will help elucidate their role in physiology and disease. Here we will examine redox probes currently available and how ROS generation may vary between subcellular compartments. Furthermore, we will discuss ROS compartmentalization in physiological and pathological conditions focusing our attention on mitochondria, since their vulnerability to oxidative stress is likely at the basis of several diseases.

  18. Statins: Pleiotropic Regulators of Cardiovascular Redox State

    Science.gov (United States)

    Channon, Keith M.

    2014-01-01

    Abstract Lipid-lowering treatment with statins is one of the most effective therapeutic strategies in cardiovascular medicine because they reduce cardiovascular risk in both primary and secondary prevention. Despite the well-established links between low-density lipoprotein and cardiovascular risk, the clinical benefit from statin treatment is not fully explained by their lipid-lowering potential. A number of pleiotropic effects of statins have been described over the past decade, and their ability to suppress global oxidative stress is probably one of the most important mechanisms by which they exert their beneficial effects on the cardiovascular system. In this Forum, there are review articles discussing the molecular mechanisms by which statins modify redox signaling in the vasculature and the heart. They exert direct effects on the vascular wall and the myocardium or indirect by targeting the interactions between the cardiovascular system and adipose tissue or circulating cell types. The review articles in this Forum follow a translational approach and link the molecular mechanisms by which statins modify cardiovascular redox signaling with their clinical benefit in the prevention and treatment of cardiovascular diseases. Antioxid. Redox Signal. 20, 1195–1197. PMID:24409984

  19. Redox control of plant growth and development.

    Science.gov (United States)

    Kocsy, Gábor; Tari, Irma; Vanková, Radomíra; Zechmann, Bernd; Gulyás, Zsolt; Poór, Péter; Galiba, Gábor

    2013-10-01

    Redox changes determined by genetic and environmental factors display well-organized interactions in the control of plant growth and development. Diurnal and seasonal changes in the environmental conditions are important for the normal course of these physiological processes and, similarly to their mild irregular alterations, for stress adaptation. However, fast or large-scale environmental changes may lead to damage or death of sensitive plants. The spatial and temporal redox changes influence growth and development due to the reprogramming of metabolism. In this process reactive oxygen and nitrogen species and antioxidants are involved as components of signalling networks. The control of growth, development and flowering by reactive oxygen and nitrogen species and antioxidants in interaction with hormones at organ, tissue, cellular and subcellular level will be discussed in the present review. Unsolved problems of the field, among others the need for identification of new components and interactions in the redox regulatory network at various organization levels using systems biology approaches will be also indicated. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  20. Redox Regulation in Amyotrophic Lateral Sclerosis

    Directory of Open Access Journals (Sweden)

    Sonam Parakh

    2013-01-01

    Full Text Available Amyotrophic lateral sclerosis (ALS is a neurodegenerative disease that results from the death of upper and lower motor neurons. Due to a lack of effective treatment, it is imperative to understand the underlying mechanisms and processes involved in disease progression. Regulations in cellular reduction/oxidation (redox processes are being increasingly implicated in disease. Here we discuss the possible involvement of redox dysregulation in the pathophysiology of ALS, either as a cause of cellular abnormalities or a consequence. We focus on its possible role in oxidative stress, protein misfolding, glutamate excitotoxicity, lipid peroxidation and cholesterol esterification, mitochondrial dysfunction, impaired axonal transport and neurofilament aggregation, autophagic stress, and endoplasmic reticulum (ER stress. We also speculate that an ER chaperone protein disulphide isomerase (PDI could play a key role in this dysregulation. PDI is essential for normal protein folding by oxidation and reduction of disulphide bonds, and hence any disruption to this process may have consequences for motor neurons. Addressing the mechanism underlying redox regulation and dysregulation may therefore help to unravel the molecular mechanism involved in ALS.

  1. A redox-mediated Kemp eliminase

    Science.gov (United States)

    Li, Aitao; Wang, Binju; Ilie, Adriana; Dubey, Kshatresh D.; Bange, Gert; Korendovych, Ivan V.; Shaik, Sason; Reetz, Manfred T.

    2017-03-01

    The acid/base-catalysed Kemp elimination of 5-nitro-benzisoxazole forming 2-cyano-4-nitrophenol has long served as a design platform of enzymes with non-natural reactions, providing new mechanistic insights in protein science. Here we describe an alternative concept based on redox catalysis by P450-BM3, leading to the same Kemp product via a fundamentally different mechanism. QM/MM computations show that it involves coordination of the substrate's N-atom to haem-Fe(II) with electron transfer and concomitant N-O heterolysis liberating an intermediate having a nitrogen radical moiety Fe(III)-N. and a phenoxyl anion. Product formation occurs by bond rotation and H-transfer. Two rationally chosen point mutations cause a notable increase in activity. The results shed light on the prevailing mechanistic uncertainties in human P450-catalysed metabolism of the immunomodulatory drug leflunomide, which likewise undergoes redox-mediated Kemp elimination by P450-BM3. Other isoxazole-based pharmaceuticals are probably also metabolized by a redox mechanism. Our work provides a basis for designing future artificial enzymes.

  2. Measurement of Redox Potential in Nanoecotoxicological Investigations

    Directory of Open Access Journals (Sweden)

    Ratna Tantra

    2012-01-01

    Full Text Available Redox potential has been identified by the Organisation for Economic Co-operation and Development (OECD as one of the parameters that should be investigated for the testing of manufactured nanomaterials. There is still some ambiguity concerning this parameter, i.e., as to what and how to measure, particularly when in a nanoecotoxicological context. In this study the redox potentials of six nanomaterials (either zinc oxide (ZnO or cerium oxide (CeO2 dispersions were measured using an oxidation-reduction potential (ORP electrode probe. The particles under testing differed in terms of their particle size and dispersion stability in deionised water and in various ecotox media. The ORP values of the various dispersions and how they fluctuate relative to each other are discussed. Results show that the ORP values are mainly governed by the type of liquid media employed, with little contributions from the nanoparticles. Seawater was shown to have reduced the ORP value, which was attributed to an increase in the concentration of reducing agents such as sulphites or the reduction of dissolved oxygen concentration. The lack of redox potential value contribution from the particles themselves is thought to be due to insufficient interaction of the particles at the Pt electrode of the ORP probe.

  3. Membrane development for vanadium redox flow batteries.

    Science.gov (United States)

    Schwenzer, Birgit; Zhang, Jianlu; Kim, Soowhan; Li, Liyu; Liu, Jun; Yang, Zhenguo

    2011-10-17

    Large-scale energy storage has become the main bottleneck for increasing the percentage of renewable energy in our electricity grids. Redox flow batteries are considered to be among the best options for electricity storage in the megawatt range and large demonstration systems have already been installed. Although the full technological potential of these systems has not been reached yet, currently the main problem hindering more widespread commercialization is the high cost of redox flow batteries. Nafion, as the preferred membrane material, is responsible for about 11% of the overall cost of a 1 MW/8 MWh system. Therefore, in recent years two main membrane related research threads have emerged: 1) chemical and physical modification of Nafion membranes to optimize their properties with regard to vanadium redox flow battery (VRFB) application; and 2) replacement of the Nafion membranes with different, less expensive materials. This review summarizes the underlying basic scientific issues associated with membrane use in VRFBs and presents an overview of membrane-related research approaches aimed at improving the efficiency of VRFBs and making the technology cost-competitive. Promising research strategies and materials are identified and suggestions are provided on how materials issues could be overcome.

  4. Redox Regulation in Amyotrophic Lateral Sclerosis

    Science.gov (United States)

    Parakh, Sonam; Spencer, Damian M.; Halloran, Mark A.; Soo, Kai Y.; Atkin, Julie D.

    2013-01-01

    Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that results from the death of upper and lower motor neurons. Due to a lack of effective treatment, it is imperative to understand the underlying mechanisms and processes involved in disease progression. Regulations in cellular reduction/oxidation (redox) processes are being increasingly implicated in disease. Here we discuss the possible involvement of redox dysregulation in the pathophysiology of ALS, either as a cause of cellular abnormalities or a consequence. We focus on its possible role in oxidative stress, protein misfolding, glutamate excitotoxicity, lipid peroxidation and cholesterol esterification, mitochondrial dysfunction, impaired axonal transport and neurofilament aggregation, autophagic stress, and endoplasmic reticulum (ER) stress. We also speculate that an ER chaperone protein disulphide isomerase (PDI) could play a key role in this dysregulation. PDI is essential for normal protein folding by oxidation and reduction of disulphide bonds, and hence any disruption to this process may have consequences for motor neurons. Addressing the mechanism underlying redox regulation and dysregulation may therefore help to unravel the molecular mechanism involved in ALS. PMID:23533690

  5. Tuning of redox regulatory mechanisms, reactive oxygen species and redox homeostasis under salinity stress

    Directory of Open Access Journals (Sweden)

    Hossain eSazzad

    2016-05-01

    Full Text Available Soil salinity is a crucial environmental constraint which limits biomass production at many sites on a global scale. Saline growth conditions cause osmotic and ionic imbalances, oxidative stress and perturb metabolism, e.g. the photosynthetic electron flow. The plant ability to tolerate salinity is determined by multiple biochemical and physiological mechanisms protecting cell functions, in particular by regulating proper water relations and maintaining ion homeostasis. Redox homeostasis is a fundamental cell property. Its regulation includes control of reactive oxygen species (ROS generation, sensing deviation from and readjustment of the cellular redox state. All these redox related functions have been recognized as decisive factors in salinity acclimation and adaptation. This review focuses on the core response of plants to overcome the challenges of salinity stress through regulation of ROS generation and detoxification systems and to maintain redox homeostasis. Emphasis is given to the role of NADH oxidase (RBOH, alternative oxidase (AOX, the plastid terminal oxidase (PTOX and the malate valve with the malate dehydrogenase isoforms under salt stress. Overwhelming evidence assigns an essential auxiliary function of ROS and redox homeostasis to salinity acclimation of plants.

  6. Crossing redox boundaries--aquifer redox history and effects on iron mineralogy and arsenic availability.

    Science.gov (United States)

    Banning, Andre; Rüde, Thomas R; Dölling, Bettina

    2013-11-15

    Cretaceous shallow marine sediments from northwestern Germany exhibit a distinct colour and geochemical boundary in a depth of several decametres, witnessing a terrestrial oxidative paleo redox process which resulted in cement loss and oxidation of Fe(II) phases. Sediment samples were obtained from boreholes drilled in near-coastal and further basinward paleo environments, including both reduced and oxidized redox facies, to characterize As and Fe occurrence in unaltered layers and redistributional consequences of the redox event. Geochemical and mineralogical composition and As fractionation were assessed. Arsenic resides in pyrite in the reduced section with a bulk rock maximum concentration of 39 μg g(-1), calculated Aspyrite is ~0.2 wt.%. Siderite concretions in the fine sands do not function as As sinks, neither does glauconite whose general As/Fe leaching behaviour was characterized. In the zone of redox transition, reduced and oxidized phases coexist and elevated As concentrations (up to 73 μg g(-1)) with high proportions of reactive As were detected. Arsenic behaviour changes from relatively homogeneous Fe sulphide-control in the unaltered sediments to very heterogeneous Fe hydroxide-control above the paleo redox boundary. The studied characteristics determine recent As availability in the subsurface and must be considered during groundwater extraction from this highly important aquifer. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Stimulus-dependent maximum entropy models of neural population codes.

    Directory of Open Access Journals (Sweden)

    Einat Granot-Atedgi

    Full Text Available Neural populations encode information about their stimulus in a collective fashion, by joint activity patterns of spiking and silence. A full account of this mapping from stimulus to neural activity is given by the conditional probability distribution over neural codewords given the sensory input. For large populations, direct sampling of these distributions is impossible, and so we must rely on constructing appropriate models. We show here that in a population of 100 retinal ganglion cells in the salamander retina responding to temporal white-noise stimuli, dependencies between cells play an important encoding role. We introduce the stimulus-dependent maximum entropy (SDME model-a minimal extension of the canonical linear-nonlinear model of a single neuron, to a pairwise-coupled neural population. We find that the SDME model gives a more accurate account of single cell responses and in particular significantly outperforms uncoupled models in reproducing the distributions of population codewords emitted in response to a stimulus. We show how the SDME model, in conjunction with static maximum entropy models of population vocabulary, can be used to estimate information-theoretic quantities like average surprise and information transmission in a neural population.

  8. Are fish less responsive to a flow stimulus when swimming?

    Science.gov (United States)

    Feitl, Karla E; Ngo, Victoria; McHenry, Matthew J

    2010-09-15

    Fish use the lateral line system to sense the water flow created by a predator's strike. Despite its potential importance to the survival of a diversity of species, it is unclear whether this ability becomes compromised when a fish swims. Therefore, the present study compared the behavioral responsiveness of swimming and motionless zebrafish (Danio rerio) larvae when exposed to the flow of a suction-feeding predator. This flow was generated with an impulse chamber, which is a device that we developed to generate a repeatable stimulus with a computer-controlled servo motor. Using high-speed video recordings, we found that about three-quarters (0.76, N=121) of motionless larvae responded to the stimulus with an escape response. These larvae were 66% more likely to respond to flow directed perpendicular than flow running parallel to the body. Swimming larvae exhibited a 0.40 response probability and were therefore nearly half as likely to respond to flow as motionless larvae. However, the latency between stimulus and response was unaffected by swimming or the direction of flow. Therefore, swimming creates changes in the hydrodynamics or neurophysiology of a larval fish that diminish the probability, but not the speed, of their response to a flow stimulus. These findings demonstrate a sensory benefit to the intermittent swimming behavior observed among a broad diversity of fishes.

  9. Stimulus Characteristics Affect Humor Processing in Individuals with Asperger Syndrome

    Science.gov (United States)

    Samson, Andrea C.; Hegenloh, Michael

    2010-01-01

    The present paper aims to investigate whether individuals with Asperger syndrome (AS) show global humor processing deficits or whether humor comprehension and appreciation depends on stimulus characteristics. Non-verbal visual puns, semantic and Theory of Mind cartoons were rated on comprehension, funniness and the punchlines were explained. AS…

  10. Molecular Mechanisms of Olfactory Responses to Stimulus Mixtures

    Science.gov (United States)

    1991-02-26

    transduction process which transmits stimulus-encoded information across the plasma membrane. A variety of biochemical and electrophysiologcl...preparations were then resolved in SDS-polyacrylamide gels, transferred to Westran mambranes and probed with each of the three antibodies described in

  11. The Effects of Signaling Stimulus Presentation during Noncontingent Reinforcement

    Science.gov (United States)

    Gouboth, Djimir; Wilder, David A.; Booher, John

    2007-01-01

    The effects of signaling the return of items or attention during treatment with noncontingent reinforcement were examined. First, functional analyses showed that the problem behavior exhibited by 2 teenagers with developmental disabilities was sensitive to social positive reinforcement. Next, delivery of the stimulus that maintained problem…

  12. Combining Stimulus Fading, Reinforcement, and Extinction To Treat Food Refusal.

    Science.gov (United States)

    Freeman, Kurt A.; Piazza, Cathleen C.

    1998-01-01

    The food refusal of a 6-year-old girl with autism and destructive behavior was treated using stimulus fading, reinforcement, and escape extinction. Intake increased, and compliance with prompting procedures remained relatively stable despite the increased consumption requirement. (Author/CR)

  13. Salivary conditioning with antennal gustatory unconditioned stimulus in an insect.

    Science.gov (United States)

    Watanabe, Hidehiro; Sato, Chihiro; Kuramochi, Tomokazu; Nishino, Hiroshi; Mizunami, Makoto

    2008-07-01

    Classical conditioning of olfactory conditioning stimulus (CS) with gustatory unconditioned stimulus (US) in insects has been used as a pertinent model for elucidation of neural mechanisms underlying learning and memory. However, a conditioning system in which stable intracellular recordings from brain neurons are feasibly obtained while monitoring the conditioning effect has remained to be established. Recently, we found classical conditioning of salivation in cockroaches Periplaneta americana, in which an odor was associated with sucrose solution applied to the mouth, and this conditioning could be monitored by activities of salivary neurons. Application of gustatory US to the mouth, however, leads to feeding movement accompanying a movement of the brain that prevents stable recordings from brain neurons. Here we investigated whether a gustatory stimulus presented to an antenna could serve as an effective US for producing salivary conditioning. Presentation of sucrose or sodium chloride solution to an antenna induced salivation and also increased activities of salivary neurons. A single pairing trial of an odor with antennal presentation of sucrose or sodium chloride solution produced conditioning of salivation or of activities of salivary neurons. Five pairing trials led to a conditioning effect that lasted for one day. Water or tactile stimulus presented to an antenna was not effective for producing conditioning. The results demonstrate that gustatory US presented to an antenna is as effective as that presented to the mouth for producing salivary conditioning. This conditioning system provides a useful model for studying the neural basis of learning at the level of singly identifiable neurons.

  14. Promoting Response Variability and Stimulus Generalization in Martial Arts Training

    Science.gov (United States)

    Harding, Jay W.; Wacker, David P.; Berg, Wendy K.; Rick, Gary; Lee, John F.

    2004-01-01

    The effects of reinforcement and extinction on response variability and stimulus generalization in the punching and kicking techniques of 2 martial arts students were evaluated across drill and sparring conditions. During both conditions, the students were asked to demonstrate different techniques in response to an instructor's punching attack.…

  15. Compound Stimulus Extinction Reduces Spontaneous Recovery in Humans

    Science.gov (United States)

    Coelho, Cesar A. O.; Dunsmoor, Joseph E.; Phelps, Elizabeth A.

    2015-01-01

    Fear-related behaviors are prone to relapse following extinction. We tested in humans a compound extinction design ("deepened extinction") shown in animal studies to reduce post-extinction fear recovery. Adult subjects underwent fear conditioning to a visual and an auditory conditioned stimulus (CSA and CSB, respectively) separately…

  16. A Dynamic Stimulus-Driven Model of Signal Detection

    Science.gov (United States)

    Turner, Brandon M.; Van Zandt, Trisha; Brown, Scott

    2011-01-01

    Signal detection theory forms the core of many current models of cognition, including memory, choice, and categorization. However, the classic signal detection model presumes the a priori existence of fixed stimulus representations--usually Gaussian distributions--even when the observer has no experience with the task. Furthermore, the classic…

  17. Multidimensional Vector Model of Stimulus-Response Compatibility

    Science.gov (United States)

    Yamaguchi, Motonori; Proctor, Robert W.

    2012-01-01

    The present study proposes and examines the multidimensional vector (MDV) model framework as a modeling schema for choice response times. MDV extends the Thurstonian model, as well as signal detection theory, to classification tasks by taking into account the influence of response properties on stimulus discrimination. It is capable of accounting…

  18. Psilocybin-induced stimulus control in the rat.

    Science.gov (United States)

    Winter, J C; Rice, K C; Amorosi, D J; Rabin, R A

    2007-10-01

    Although psilocybin has been trained in the rat as a discriminative stimulus, little is known of the pharmacological receptors essential for stimulus control. In the present investigation rats were trained with psilocybin and tests were then conducted employing a series of other hallucinogens and presumed antagonists. An intermediate degree of antagonism of psilocybin was observed following treatment with the 5-HT(2A) receptor antagonist, M100907. In contrast, no significant antagonism was observed following treatment with the 5-HT(1A/7) receptor antagonist, WAY-100635, or the DA D(2) antagonist, remoxipride. Psilocybin generalized fully to DOM, LSD, psilocin, and, in the presence of WAY-100635, DMT while partial generalization was seen to 2C-T-7 and mescaline. LSD and MDMA partially generalized to psilocybin and these effects were completely blocked by M-100907; no generalization of PCP to psilocybin was seen. The present data suggest that psilocybin induces a compound stimulus in which activity at the 5-HT(2A) receptor plays a prominent but incomplete role. In addition, psilocybin differs from closely related hallucinogens such as 5-MeO-DMT in that agonism at 5-HT(1A) receptors appears to play no role in psilocybin-induced stimulus control.

  19. Fechnerian metrics in unidimensional and multidimensional stimulus spaces.

    Science.gov (United States)

    Dzhafarov, E N; Colonius, H

    1999-06-01

    A new theory is proposed for subjective (Fechnerian) distances among stimuli in a continuous stimulus space of arbitrary dimensionality. Each stimulus in such a space is associated with a psychometric function that determines probabilities with which it is discriminated from other stimuli, and a certain measure of its discriminability from its infinitesimally close neighboring stimuli is computed from the shape of this psychometric function in the vicinity of its minimum. This measure of discriminability can be integrated along any path connecting any two points in the stimulus space, yielding the psychometric length of this path. The Fechnerian distance between two stimuli is defined as the infimum of the psychometric lengths of all paths connecting the two stimuli. For a broad class of models defining the dichotomy of response bias versus discriminability, the Fechnerian distances are invariant under response bias changes. In the case in which physically multidimensional stimuli are discriminated along some unidimensional subjective attribute, a systematic construction of the Fechnerian metric leads to a resolution of the long-standing controversy related to the numbers of just-noticeable differences between isosensitivity curves. It is argued that for unidimensional stimulus continua, the proposed theory is close to the intended meaning of Fechner's original theory.

  20. Characterisation of the Redox Sensitive NMDA Receptor

    KAUST Repository

    Alzahrani, Ohood

    2016-05-01

    Glucose entry into the brain and its subsequent metabolism to L-lactate, regulated by astrocytes, plays a major role in synaptic plasticity and memory formation. A recent study has shown that L-lactate produced by the brain upon stimulation of glycolysis, and glycogen-derived L-lactate from astrocytes and its transport into neurons, is crucial for memory formation. A recent study revealed the molecular mechanisms that underlie the role of L-lactate in neuronal plasticity and long-term memory formation. L-lactate was shown to induce a cascade of molecular events via modulation of redox-sensitive N-Methyl-D-aspartate (NMDA) receptor activity that was mimicked by nicotinamide adenine dinucleotide hydride (NADH) co-enzyme. This indicated that changes in cellular redox state, following L-lactate transport inside the cells and its subsequent metabolism, production of NADH, and favouring a reduced state are the key effects of L-lactate. Therefore, we are investigating the role of L-lactate in modulating NMDA receptor function via redox modulatory sites. Accordingly, crucial redox-sensitive cysteine residues, Cys320 and Cys87, of the NR2A NMDA receptor subunit are mutated using site-directed mutation, transfected, and expressed in HEK293 cells. This cellular system will then be used to characterise and monitor its activity upon Llactate stimulation, compared to the wild type. This will be achieved by calcium imaging, using fluorescent microscopy. Our data shows that L-lactate potentiated NMDA receptor activity and increased intracellular calcium influx in NR1/NR2A wild type compared to the control condition (WT NR1/NR2A perfused with (1μM) glutamate and (1μM) glycine agonist only), showing faster response initiation and slower decay rate of the calcium signal to the baseline. Additionally, stimulating with L-lactate associated with greater numbers of cells having high fluorescent intensity (peak amplitude) compared to the control. Furthermore, L-lactate rescued the

  1. Redox Enzymes of Red Beetroot Vacuoles (Beta vulgaris L.

    Directory of Open Access Journals (Sweden)

    E.V. Pradedova

    2014-12-01

    Full Text Available Years of research have shown that some of the redox elements (enzymes, coenzymes, and co-substrate are isolated from each other kinetic and spatial manner (compartmentalization in the eukaryotic cells. The redox elements forming the "highly" and "widely" specialized redox system are found in all cell structures: mitochondria, plastids, peroxisomes, apoplast, nucleus etc. In recent years the active involvement of the central vacuole in the maintenance of the plant cell redox homeostasis is discussed, actually the information about the vacuolar redox system is very small. The high-priority redox processes and "redox-specialization" of the vacuolar compartment are not known. We have begun a study of red beet-root vacuole redox systems (Beta vulgaris L. and have identified redox enzymes such as: phenol peroxidase (EC 1.11.1.7, superoxide dismutase (EC 1.15.1.1 and glutathione reductase (EC 1.8.1.7. This paper presents some of the characteristics of these enzymes and considers the probable ways of their functioning in vacuolar redox chains.

  2. Redox Regulation of Inflammatory Processes Is Enzymatically Controlled

    Directory of Open Access Journals (Sweden)

    Inken Lorenzen

    2017-01-01

    Full Text Available Redox regulation depends on the enzymatically controlled production and decay of redox active molecules. NADPH oxidases, superoxide dismutases, nitric oxide synthases, and others produce the redox active molecules superoxide, hydrogen peroxide, nitric oxide, and hydrogen sulfide. These react with target proteins inducing spatiotemporal modifications of cysteine residues within different signaling cascades. Thioredoxin family proteins are key regulators of the redox state of proteins. They regulate the formation and removal of oxidative modifications by specific thiol reduction and oxidation. All of these redox enzymes affect inflammatory processes and the innate and adaptive immune response. Interestingly, this regulation involves different mechanisms in different biological compartments and specialized cell types. The localization and activity of distinct proteins including, for instance, the transcription factor NFκB and the immune mediator HMGB1 are redox-regulated. The transmembrane protein ADAM17 releases proinflammatory mediators, such as TNFα, and is itself regulated by a thiol switch. Moreover, extracellular redox enzymes were shown to modulate the activity and migration behavior of various types of immune cells by acting as cytokines and/or chemokines. Within this review article, we will address the concept of redox signaling and the functions of both redox enzymes and redox active molecules in innate and adaptive immune responses.

  3. Discriminative stimulus effects of nalbuphine in rhesus monkeys.

    Science.gov (United States)

    Gerak, L R; France, C P

    1996-02-01

    Three rhesus monkeys discriminated between 0.178 mg/kg of nalbuphine and saline while responding under a fixed-ratio 5 schedule of stimulus-shock termination. Nalbuphine produced dose-related increases in drug-lever responding with > or = 90% of responses occurring on the drug lever at doses larger than 0.1 mg/kg. The duration of action of the discriminative stimulus effects of nalbuphine was less than 5.25 hr. Rank order potency of compounds that substituted for the nalbuphine discriminative stimulus (i.e., > or = 90% responding on the nalbuphine lever) in all three subjects was fentanyl > butorphanol > methadone > morphine. Compounds that did not substitute completely in all monkeys included the kappa agonists ethylketocyclazocine, enadoline, spiradoline and U-50,488 and the nonopioids cocaine, d-amphetamine, clonidine, ketamine and phencyclidine. Naltrexone antagonized the discriminative stimulus effects of nalbuphine, shifting the nalbuphine dose-effect curve in a manner that was consistent with mu receptor mediation. Results from the current study demonstrate that, in rhesus monkeys, the discriminative stimulus effects of nalbuphine are mediated by mu opioid receptors. Although there is evidence suggesting that nalbuphine has kappa agonist effects (e.g., subjective effects in humans), results from several studies, including the current study, strongly suggest that in rhesus monkeys nalbuphine does not exert agonist actions at kappa receptors. Moreover, these data indicate that differences in behavioral effects between nalbuphine and prototypic mu opioids (e.g., morphine) probably result from differences in activity (e.g., efficacy) at mu receptors rather than any kappa agonist actions of nalbuphine.

  4. Discriminative stimulus effects of pregnanolone in rhesus monkeys.

    Science.gov (United States)

    Gerak, Lisa R; France, Charles P

    2014-01-01

    Neuroactive steroids and benzodiazepines can positively modulate GABA by acting at distinct binding sites on synaptic GABA(A) receptors. Although these receptors are thought to mediate the behavioral effects of both benzodiazepines and neuroactive steroids, other receptors (e.g., extrasynaptic GABA(A), N-methyl-D-aspartate (NMDA), σ₁, or 5-HT₃ receptors) might contribute to the effects of neuroactive steroids, accounting for differences among positive modulators. The current study established the neuroactive steroid pregnanolone as a discriminative stimulus to determine whether actions in addition to positive modulation of synaptic GABA(A) receptors might contribute to its discriminative stimulus effects. Four rhesus monkeys discriminated 5.6 mg/kg pregnanolone while responding under a fixed-ratio 10 schedule of stimulus-shock termination. Positive modulators acting at benzodiazepine, barbiturate, or neuroactive steroid sites produced ≥80 % pregnanolone-lever responding, whereas drugs acting primarily at receptors other than synaptic GABA(A) receptors, such as extrasynaptic GABA(A), NMDA, σ₁, and 5-HT₃ receptors, produced vehicle-lever responding. Flumazenil antagonized the benzodiazepines midazolam and flunitrazepam, with Schild analyses yielding slopes that did not deviate from unity and pA₂ values of 7.39 and 7.32, respectively. Flumazenil did not alter the discriminative stimulus effects of pregnanolone. While these results do not exclude the possibility that pregnanolone acts at receptors other than synaptic GABA(A) receptors, they indicate a primary and possibly exclusive role of synaptic GABA(A) receptors in its discriminative stimulus effects. Reported differences in the effects of benzodiazepines and neuroactive steroids are not due to differences in their actions at synaptic GABA(A) receptors.

  5. How to combine sparse proxy data and coupled climate models

    Science.gov (United States)

    Paul, André; Schäfer-Neth, Christian

    2005-04-01

    We address the problem of reconstructing a global field from proxy data with sparse spatial sampling such as the MARGO (multi-proxy approach for the reconstruction of the glacial ocean surface) SST (sea-surface temperature) and δ18O c (oxygen-18/oxygen-16 isotope ratio preserved in fossil carbonate shells of planktic foraminifera) data. To this end, we propose to `assimilate' these data into coupled climate models by adjusting some of their parameters and optimizing the fit. In particular, we suggest to combine a forward model and an objective function that quantifies the misfit to the data. Because of their computational efficiency, earth system models of intermediate complexity are particularly well-suited for this purpose. We used one such model (the University of Victoria Earth System Climate Model) and carried out a series of sensitivity experiments by varying a single model parameter through changing the atmospheric CO2 concentration. The unanalyzed World Ocean Atlas SST and the observed sea-ice concentration served as present-day targets. The sparse data coverage as implied by the locations of 756 ocean sediment cores from the MARGO SST database was indeed sufficient to determine the best fit. As anticipated, it turned out to be the 365 ppm experiment. We also found that the 200 ppm experiment came surprisingly close to what is commonly expected for the Last Glacial Maximum ocean circulation. Our strategy has a number of advantages over more traditional mapping methods, e.g., there is no need to force the results of different proxies into a single map, because they can be compared to the model output one at a time, properly taking into account the different seasons of plankton growth or varying depth habitats. It can be extended to more model parameters and even be automated.

  6. Patient-rated versus proxy-rated cognitive and functional measures in older adults

    Science.gov (United States)

    Howland, Molly; Allan, Kevin C; Carlton, Caitlin E; Tatsuoka, Curtis; Smyth, Kathleen A; Sajatovic, Martha

    2017-01-01

    Objectives Patients with cognitive impairment may have difficulty reporting their functional and cognitive abilities, which are important clinical outcomes. Health care proxies may be able to corroborate patient self-reports. Several studies reported discrepancy between patient and proxy ratings, though the literature is sparse on changes over time of these ratings. Our goals in this 12-month study were to compare patient and proxy reports on functioning, cognition, and everyday executive function, and to further elucidate correlates of patient–proxy discrepancy. Methods This was a prospective cohort study of individuals older than 70 years who ranged from having no cognitive impairment to having moderate dementia who had a proxy available to complete instruments at baseline (N=76). Measurements included Alzheimer’s Disease Cooperative Study–Activities of Daily Living Inventory (ADCS-ADLI), Neuro-QOL Executive Function, PROMIS Applied Cognition (PROMIS-Cog), Mini-Mental State Examination (MMSE), and Geriatric Depression Scale. Results Patient- and proxy-rated ADCS-ADLI were correlated at baseline and at 1-year follow-up. Patient and proxy ratings were discrepant on Neuro-QOL Executive Function and PROMIS-Cog. Greater patient–proxy discrepancy on PROMIS-Cog was associated with younger age and less depression, and greater patient–proxy discrepancy on Neuro-QOL Executive Function was associated with less depression and worse cognitive impairment. Patient–proxy discrepancy increased over time for everyday executive function. Changes in proxy-rated but not patient-rated ADCS-ADLI correlated with MMSE changes. Conclusion Patients and proxies generally agree in reporting on activities of daily living. Patient and proxy reports differ in their respective evaluation of cognitive functioning and everyday executive function. Ratings from both sources may be preferred for these two domains, though studies using gold standard measures are necessary. It is important

  7. Tycho 2: A Proxy Application for Kinetic Transport Sweeps

    Energy Technology Data Exchange (ETDEWEB)

    Garrett, Charles Kristopher [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Computer, Computational, and Statistical Sciences Division; Warsa, James S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Computer, Computational, and Statistical Sciences Division

    2016-09-14

    Tycho 2 is a proxy application that implements discrete ordinates (SN) kinetic transport sweeps on unstructured, 3D, tetrahedral meshes. It has been designed to be small and require minimal dependencies to make collaboration and experimentation as easy as possible. Tycho 2 has been released as open source software. The software is currently in a beta release with plans for a stable release (version 1.0) before the end of the year. The code is parallelized via MPI across spatial cells and OpenMP across angles. Currently, several parallelization algorithms are implemented.

  8. Nursing interventions in Münchausen syndrome by proxy.

    Science.gov (United States)

    Volz, A G

    1995-09-01

    1. Münchausen syndrome by proxy is a rare but serious and potentially lethal form of child abuse in which a primary care giver induces or reports factitious symptoms in a child. 2. The child suffers from the caregiver's actions and health care providers unknowingly become accomplices when they provide unnecessary testing and therapies. 3. The child's physical and psychological welfare can be protected through the efforts of the forensic nurse specialist coordinating a multidisciplinary health care team's work to detect the syndrome and intervene early on.

  9. Compliance with treatment in asthma and Munchausen syndrome by proxy.

    Science.gov (United States)

    Godding, V; Kruth, M

    1991-01-01

    Among 1648 asthmatic patients, 17 families (1%) were identified as having Munchausen syndrome by proxy. Ten families did not treat their children's, attacks or refused medical care, and seven exaggerated the severity of symptoms to obtain invasive investigations and treatment. All the families had disturbed psychosocial backgrounds. The abuse consisted mainly of neglect, in that necessary treatment was not given. In some cases a more direct form of abuse was observed, when useless and sometimes harmful investigations and treatment were given. We conclude that medical control of the compliance of both parents and children is necessary in the management of childhood asthma. PMID:1929492

  10. Investigating genetic loci that encode plant-derived paleoclimate proxies

    Science.gov (United States)

    Bender, A. L. D.; Suess, M.; Chitwood, D. H.; Bradley, A. S.

    2016-12-01

    Long chain (>C25) n-alkanes in sediments predominantly derive from terrestrial plant waxes. Hydrogen isotope ratios (δD) of leaf wax hydrocarbons correlate with δDH2O of precipitation and are commonly used as paleoclimate proxies. However, biological variability in the isotopic fractionations between water and plant materials also affects the n-alkane δD values. Correct interpretation of this paleoclimate proxy requires that we resolve genetic and environmental effects. Genetic variability underlying differences in leaf wax structure and isotopic composition can be quantitatively determined through the use of model organisms. Interfertile Solanum sect. Lycopersicon (tomato) species provide an ideal model species complex for this approach. We used a set of 76 precisely defined near-isogenic lines (introgression lines [ILs]) in which small genomic regions from the wild tomato relative Solanum pennellii have been introduced into the genome of the domestic tomato, S. lycopersicum. By characterizing quantitative traits of these ILs (leaf wax structure and isotopic composition), we can resolve the degree to which each trait is regulated by genetic versus environmental factors. We present data from two growth experiments conducted with all 76 ILs. In this study, we quantify leaf wax traits, including δD values, δ13C values, and structural metrics including the methylation index (a variable that describes the ratio of iso­- and anteiso- to n-alkanes). Among ILs, δD values vary by up to 35‰ and 60‰ for C31 and C33 n-alkanes, respectively. Many ILs have methylation indices that are discernably different from the parent domesticated tomato (p < 0.001), which suggests that methylation is a highly polygenic trait. This pattern is similar to the genetics that control leaf shape, another trait commonly used as a paleoclimate proxy. Based on our preliminary analysis, we propose candidate genes that control aspects of plant physiology that affect these quantitative

  11. Exploring the redox balance inside gram-negative bacteria with redox-sensitive GFP.

    Science.gov (United States)

    van der Heijden, Joris; Vogt, Stefanie L; Reynolds, Lisa A; Peña-Díaz, Jorge; Tupin, Audrey; Aussel, Laurent; Finlay, B Brett

    2016-02-01

    Aerobic bacteria are continuously fighting potential oxidative stress due to endogenous and exogenous reactive oxygen species (ROS). To achieve this goal, bacteria possess a wide array of defenses and stress responses including detoxifying enzymes like catalases and peroxidases; however until now, the dynamics of the intra-bacterial redox balance remained poorly understood. Herein, we used redox-sensitive GFP (roGFP2) inside a variety of gram-negative bacteria to study real-time redox dynamics immediately after a challenge with hydrogen peroxide. Using this biosensor, we determined the individual contributions of catalases and peroxidases and found that each enzyme contributes more to rapid detoxification or to prolonged catalytic activity. We also found that the total catalytic power is affected by environmental conditions. Additionally, using a Salmonella strain that is devoid of detoxifying enzymes, we examined endogenous ROS production. By measuring endogenous ROS production, we assessed the role of oxidative stress in toxicity of heavy metals and antibiotics. We found that exposure to nickel induced significant oxidative stress whereas cobalt (which was previously implicated to induce oxidative stress) did not induce ROS formation. Since a turbulent debate evolves around oxidative stress as a general killing mechanism by antibiotics (aminoglycosides, fluoroquinolones and β-lactams), we measured oxidative stress in bacteria that were challenged with these antibiotics. Our results revealed that antibiotics do not induce ROS formation in bacteria thereby disputing a role for oxidative stress as a general killing mechanism. Together, our results expose how the intra-bacterial redox balance in individual microorganisms is affected by environmental conditions and encounters with stress-inducing compounds. These findings demonstrate the significant potential of roGFP2 as a redox biosensor in gram-negative bacteria to investigate redox dynamics under a variety of

  12. Comfort with proxy consent to research involving decisionally impaired older adults: do type of proxy and risk-benefit profile matter?

    Science.gov (United States)

    Dubois, Marie-France; Bravo, Gina; Graham, Janice; Wildeman, Sheila; Cohen, Carole; Painter, Karen; Bellemare, Suzanne

    2011-11-01

    Dementia research often requires the participation of people with dementia. Obtaining informed consent is problematic when potential participants lack the capacity to provide it. We investigated comfort with proxy consent to research involving older adults deemed incapable of this decision, and examined if comfort varies with the type of proxy and the study's risk-benefit profile. We surveyed random samples of five relevant groups (older adults, informal caregivers, physicians, researchers in aging, and Research Ethics Board members) from four Canadian provinces. Respondents were presented with scenarios involving four types of proxies (non-assigned, designated in a healthcare advance directive with or without instructions specific to research participation, and court-appointed). Given a series of risk-benefit profiles, respondents indicated whether they were comfortable with proxy consent to research for each scenario. Two percent of the respondents felt proxy consent should never be allowed. In all groups, comfort depended far more on the risk-benefit profile associated with the research scenario than with type of proxy. For research involving little or no risk and potential personal benefits, over 90% of the respondents felt comfortable with substitute consent by a designated or court-appointed proxy while 80% were at ease with a non-assigned proxy. For studies involving serious risks with potentially greater personal benefits, older adults and informal caregivers were less comfortable with proxy consent. A large majority of Canadians are comfortable with proxy consent for low-risk research. Further work is needed to establish what kinds of research are considered to be low risk.

  13. Context-dependent redox properties of natural phenolic materials.

    Science.gov (United States)

    Kim, Eunkyoung; Liu, Yi; Leverage, W Taylor; Yin, Jun-Jie; White, Ian M; Bentley, William E; Payne, Gregory F

    2014-05-12

    Macromolecular phenolics are among the most abundant organic molecules in nature, yet their biological activities are largely unresolved because of their structural complexity and because of an inability to probe their functionality experimentally. We developed thin film and electrochemical methodologies to probe the redox properties of melanin, lignin, and humic acid, three of the most abundant phenolic materials. We observed that all three phenolic matrixes possess redox activity and can be repeatedly switched between oxidized and reduced states. Furthermore, we observed that melanin possesses pro-oxidant activities exemplified by the uncatalyzed generation of reactive oxygen species (ROS) upon exposure to air; however, this pro-oxidant activity is observed only for melanin films that are poised in their reduced state. Conversely, melanin's antioxidant radical-scavenging activities are insensitive to its redox state. These results demonstrate that natural phenolic matrixes are not inert but rather serve as open-source redox media with significant potential for impacting redox signaling and redox biology.

  14. Thermodynamic Proxies to Compensate for Biases in Drug Discovery Methods.

    Science.gov (United States)

    Ekins, Sean; Litterman, Nadia K; Lipinski, Christopher A; Bunin, Barry A

    2016-01-01

    We propose a framework with simple proxies to dissect the relative energy contributions responsible for standard drug discovery binding activity. We explore a rule of thumb using hydrogen-bond donors, hydrogen-bond acceptors and rotatable bonds as relative proxies for the thermodynamic terms. We apply this methodology to several datasets (e.g., multiple small molecules profiled against kinases, Mycobacterium tuberculosis (Mtb) high throughput screening (HTS) and structure based drug design (SBDD) derived compounds, and FDA approved drugs). We found that Mtb active compounds developed through SBDD methods had statistically significantly larger PEnthalpy values than HTS derived compounds, suggesting these compounds had relatively more hydrogen bond donor and hydrogen bond acceptors compared to rotatable bonds. In recent FDA approved medicines we found that compounds identified via target-based approaches had a more balanced enthalpic relationship between these descriptors compared to compounds identified via phenotypic screens As it is common to experimentally optimize directly for total binding energy, these computational methods provide alternative calculations and approaches useful for compound optimization alongside other common metrics in available software and databases.

  15. Simulation of Wake Vortex Radiometric Detection via Jet Exhaust Proxy

    Science.gov (United States)

    Daniels, Taumi S.

    2015-01-01

    This paper describes an analysis of the potential of an airborne hyperspectral imaging IR instrument to infer wake vortices via turbine jet exhaust as a proxy. The goal was to determine the requirements for an imaging spectrometer or radiometer to effectively detect the exhaust plume, and by inference, the location of the wake vortices. The effort examines the gas spectroscopy of the various major constituents of turbine jet exhaust and their contributions to the modeled detectable radiance. Initially, a theoretical analysis of wake vortex proxy detection by thermal radiation was realized in a series of simulations. The first stage used the SLAB plume model to simulate turbine jet exhaust plume characteristics, including exhaust gas transport dynamics and concentrations. The second stage used these plume characteristics as input to the Line By Line Radiative Transfer Model (LBLRTM) to simulate responses from both an imaging IR hyperspectral spectrometer or radiometer. These numerical simulations generated thermal imagery that was compared with previously reported wake vortex temperature data. This research is a continuation of an effort to specify the requirements for an imaging IR spectrometer or radiometer to make wake vortex measurements. Results of the two-stage simulation will be reported, including instrument specifications for wake vortex thermal detection. These results will be compared with previously reported results for IR imaging spectrometer performance.

  16. Solar spectral irradiance datasets: analysis and comparison with proxies

    Science.gov (United States)

    Kretzschmar, M.; Schoell, M.; Dudok de Wit, T.

    2013-12-01

    Solar spectral irradiance (SSI) measurements have been acquired in space since the late 1960's. These data are of extreme importance to assess the variability of the Sun in the last decades as well as to understand how its magnetic activity affects its radiative output, and therefore to constrain the solar variability further in time. However, these data sometimes disagree between themselves or with our expectations deduced from well known observed proxies, and it is hard to disentangle instrumental effects from possible solar behavior. In the context of the european project SOLID (First European comprehensive SOlar Irradiance Data Exploitation) project, which aims at building an SSI composite with time dependent error-bars over the space age, we will show our first results towards the construction of a carefully assessed homogeneous solar spectral irradiance datasets, focussing on the ultraviolet wavelength range, for which more data are available. We will first present the data used, together with methods for gap-filling and outlier removal. Then we will show some results obtained by comparing a single dataset at different times of the mission, as well as results obtained from the comparison of simultaneous datasets and proxies. Finally, we will discuss how these analyses can help us to estimate errors on the solar variability at a particular wavelength.

  17. Attribute-based proxy re-encryption with keyword search.

    Directory of Open Access Journals (Sweden)

    Yanfeng Shi

    Full Text Available Keyword search on encrypted data allows one to issue the search token and conduct search operations on encrypted data while still preserving keyword privacy. In the present paper, we consider the keyword search problem further and introduce a novel notion called attribute-based proxy re-encryption with keyword search (ABRKS, which introduces a promising feature: In addition to supporting keyword search on encrypted data, it enables data owners to delegate the keyword search capability to some other data users complying with the specific access control policy. To be specific, ABRKS allows (i the data owner to outsource his encrypted data to the cloud and then ask the cloud to conduct keyword search on outsourced encrypted data with the given search token, and (ii the data owner to delegate other data users keyword search capability in the fine-grained access control manner through allowing the cloud to re-encrypted stored encrypted data with a re-encrypted data (embedding with some form of access control policy. We formalize the syntax and security definitions for ABRKS, and propose two concrete constructions for ABRKS: key-policy ABRKS and ciphertext-policy ABRKS. In the nutshell, our constructions can be treated as the integration of technologies in the fields of attribute-based cryptography and proxy re-encryption cryptography.

  18. Sepiapterin Reductase Mediates Chemical Redox Cycling in Lung Epithelial Cells*

    Science.gov (United States)

    Yang, Shaojun; Jan, Yi-Hua; Gray, Joshua P.; Mishin, Vladimir; Heck, Diane E.; Laskin, Debra L.; Laskin, Jeffrey D.

    2013-01-01

    In the lung, chemical redox cycling generates highly toxic reactive oxygen species that can cause alveolar inflammation and damage to the epithelium, as well as fibrosis. In this study, we identified a cytosolic NADPH-dependent redox cycling activity in mouse lung epithelial cells as sepiapterin reductase (SPR), an enzyme important for the biosynthesis of tetrahydrobiopterin. Human SPR was cloned and characterized. In addition to reducing sepiapterin, SPR mediated chemical redox cycling of bipyridinium herbicides and various quinones; this activity was greatest for 1,2-naphthoquinone followed by 9,10-phenanthrenequinone, 1,4-naphthoquinone, menadione, and 2,3-dimethyl-1,4-naphthoquinone. Whereas redox cycling chemicals inhibited sepiapterin reduction, sepiapterin had no effect on redox cycling. Additionally, inhibitors such as dicoumarol, N-acetylserotonin, and indomethacin blocked sepiapterin reduction, with no effect on redox cycling. Non-redox cycling quinones, including benzoquinone and phenylquinone, were competitive inhibitors of sepiapterin reduction but noncompetitive redox cycling inhibitors. Site-directed mutagenesis of the SPR C-terminal substrate-binding site (D257H) completely inhibited sepiapterin reduction but had minimal effects on redox cycling. These data indicate that SPR-mediated reduction of sepiapterin and redox cycling occur by distinct mechanisms. The identification of SPR as a key enzyme mediating chemical redox cycling suggests that it may be important in generating cytotoxic reactive oxygen species in the lung. This activity, together with inhibition of sepiapterin reduction by redox-active chemicals and consequent deficiencies in tetrahydrobiopterin, may contribute to tissue injury. PMID:23640889

  19. Redox homeostasis: The Golden Mean of healthy living

    Directory of Open Access Journals (Sweden)

    Fulvio Ursini

    2016-08-01

    Full Text Available The notion that electrophiles serve as messengers in cell signaling is now widely accepted. Nonetheless, major issues restrain acceptance of redox homeostasis and redox signaling as components of maintenance of a normal physiological steady state. The first is that redox signaling requires sudden switching on of oxidant production and bypassing of antioxidant mechanisms rather than a continuous process that, like other signaling mechanisms, can be smoothly turned up or down. The second is the misperception that reactions in redox signaling involve “reactive oxygen species” rather than reaction of specific electrophiles with specific protein thiolates. The third is that hormesis provides protection against oxidants by increasing cellular defense or repair mechanisms rather than by specifically addressing the offset of redox homeostasis. Instead, we propose that both oxidant and antioxidant signaling are main features of redox homeostasis. As the redox shift is rapidly reversed by feedback reactions, homeostasis is maintained by continuous signaling for production and elimination of electrophiles and nucleophiles. Redox homeostasis, which is the maintenance of nucleophilic tone, accounts for a healthy physiological steady state. Electrophiles and nucleophiles are not intrinsically harmful or protective, and redox homeostasis is an essential feature of both the response to challenges and subsequent feedback. While the balance between oxidants and nucleophiles is preserved in redox homeostasis, oxidative stress provokes the establishment of a new radically altered redox steady state. The popular belief that scavenging free radicals by antioxidants has a beneficial effect is wishful thinking. We propose, instead, that continuous feedback preserves nucleophilic tone and that this is supported by redox active nutritional phytochemicals. These nonessential compounds, by activating Nrf2, mimic the effect of endogenously produced electrophiles

  20. Redox-mediated quorum sensing in plants.

    Directory of Open Access Journals (Sweden)

    Alexandra W Fuller

    Full Text Available The rhizosphere, the narrow zone of soil around plant roots, is a complex network of interactions between plants, bacteria, and a variety of other organisms. The absolute dependence on host-derived signals, or xenognosins, to regulate critical developmental checkpoints for host commitment in the obligate parasitic plants provides a window into the rhizosphere's chemical dynamics. These sessile intruders use H2O2 in a process known as semagenesis to chemically modify the mature root surfaces of proximal host plants and generate p-benzoquinones (BQs. The resulting redox-active signaling network regulates the spatial and temporal commitments necessary for host attachment. Recent evidence from non-parasites, including Arabidopsis thaliana, establishes that reactive oxygen species (ROS production regulates similar redox circuits related to root recognition, broadening xenognosins' role beyond the parasites. Here we compare responses to the xenognosin dimethoxybenzoquinone (DMBQ between the parasitic plant Striga asiatica and the non-parasitic A. thaliana. Exposure to DMBQ simulates the proximity of a mature root surface, stimulating an increase in cytoplasmic Ca2+ concentration in both plants, but leads to remarkably different phenotypic responses in the parasite and non-parasite. In S. asiatica, DMBQ induces development of the host attachment organ, the haustorium, and decreases ROS production at the root tip, while in A. thaliana, ROS production increases and further growth of the root tip is arrested. Obstruction of Ca2+ channels and the addition of antioxidants both lead to a decrease in the DMBQ response in both parasitic and non-parasitic plants. These results are consistent with Ca2+ regulating the activity of NADPH oxidases, which in turn sustain the autocatalytic production of ROS via an external quinone/hydroquinone redox cycle. Mechanistically, this chemistry is similar to black and white photography with the emerging dynamic reaction

  1. Factors Controlling Redox Speciation of Plutonium and Neptunium in Extraction Separation Processes

    Energy Technology Data Exchange (ETDEWEB)

    Paulenova, Alena [Principal Investigator; Vandegrift, III, George F. [Collaborator

    2013-09-24

    The objective of the project was to examine the factors controlling redox speciation of plutonium and neptunium in UREX+ extraction in terms of redox potentials, redox mechanism, kinetics and thermodynamics. Researchers employed redox-speciation extractions schemes in parallel to the spectroscopic experiments. The resulting distribution of redox species w studied uring spectroscopic, electrochemical, and spectro-electrochemical methods. This work reulted in collection of data on redox stability and distribution of redox couples in the nitric acid/nitrate electrolyte and the development of redox buffers to stabilize the desired oxidation state of separated radionuclides. The effects of temperature and concentrations on the redox behavior of neptunium were evaluated.

  2. Biogeochemical redox processes and their impact on contaminant dynamics

    Science.gov (United States)

    Borch, Thomas; Kretzschmar, Ruben; Kappler, Andreas; Van Cappellen, Philippe; Ginder-Vogel, Matthew; Campbell, Kate M.

    2010-01-01

    Life and element cycling on Earth is directly related to electron transfer (or redox) reactions. An understanding of biogeochemical redox processes is crucial for predicting and protecting environmental health and can provide new opportunities for engineered remediation strategies. Energy can be released and stored by means of redox reactions via the oxidation of labile organic carbon or inorganic compounds (electron donors) by microorganisms coupled to the reduction of electron acceptors including humic substances, iron-bearing minerals, transition metals, metalloids, and actinides. Environmental redox processes play key roles in the formation and dissolution of mineral phases. Redox cycling of naturally occurring trace elements and their host minerals often controls the release or sequestration of inorganic contaminants. Redox processes control the chemical speciation, bioavailability, toxicity, and mobility of many major and trace elements including Fe, Mn, C, P, N, S, Cr, Cu, Co, As, Sb, Se, Hg, Tc, and U. Redox-active humic substances and mineral surfaces can catalyze the redox transformation and degradation of organic contaminants. In this review article, we highlight recent advances in our understanding of biogeochemical redox processes and their impact on contaminant fate and transport, including future research needs.

  3. Redox buffer capacity of the cell: theoretical and experimental approach.

    Science.gov (United States)

    Martinovich, Grigory G; Martinovich, Irina V; Cherenkevich, Sergey N; Sauer, Heinrich

    2010-11-01

    Reactive oxygen species (ROS) are involved in a variety of biological phenomena, such as mutation, carcinogenesis, inflammation, aging, development, and signal transduction. Intracellular generation of ROS might lead to the activation of redox signaling or oxidative stress. Nonetheless, it is difficult to estimate whether ROS-induced intracellular events are beneficial or deleterious to the cell. The quantitative basis of changes in the intracellular redox state of cells is not well-defined, thus leading to the dilemma that redox changes induced by oxidants in distinct cell types cannot be predicted. To overcome this limitation this study undertakes to analyze on a theoretical as well as on an experimental basis the intracellular redox state changes occurring inside cells upon addition of oxidants or reductants. 2,7-Dichlorodihydrofluorescein (H(2)DCF) was used to characterize the redox buffer capacity in erythrocytes. It was shown that the redox buffer capacity of erythrocytes in the relation to peroxynitrite (ONOO(-)) is 2.1 times lower than the redox buffer capacity of erythrocytes in the relation to hydrogen peroxide (H(2)O(2)). The feasibility of redox buffer capacity assessment as an innovative tool for investigation and description of redox signaling events in cells is discussed.

  4. Dimensional behavior of Ni-YSZ composites during redox cycling

    DEFF Research Database (Denmark)

    Pihlatie, Mikko; Kaiser, Andreas; Larsen, Peter Halvor

    2009-01-01

    The dimensional behavior of Ni-yttria-stabilized zirconia (YSZ) cermets during redox cycling was tested in dilatometry within the temperature range 600-1000 degrees C. The effect Of humidity oil redox stability was investigated at intermediate and low temperatures. We show that both the sintering...... of nickel depending on temperature of the initial reduction and the operating conditions, and the temperature of reoxidation are very important for the size of the dimensional change. Cumulative redox strain (CRS) is shown to be correlated with temperature. Measured maximum CRS after three redox cycles...

  5. Redox shuttles for lithium ion batteries

    Science.gov (United States)

    Weng, Wei; Zhang, Zhengcheng; Amine, Khalil

    2014-11-04

    Compounds may have general Formula IVA or IVB. ##STR00001## where, R.sup.8, R.sup.9, R.sup.10, and R.sup.11 are each independently selected from H, F, Cl, Br, CN, NO.sub.2, alkyl, haloalkyl, and alkoxy groups; X and Y are each independently O, S, N, or P; and Z' is a linkage between X and Y. Such compounds may be used as redox shuttles in electrolytes for use in electrochemical cells, batteries and electronic devices.

  6. Proterozoic ocean redox and biogeochemical stasis

    OpenAIRE

    Reinhard, Christopher T.; Planavsky, Noah J.; Robbins, Leslie J.; Partin, Camille A.; Gill, Benjamin C.; Lalonde, Stefan V.; Bekker, Andrey; Konhauser, Kurt O.; Lyons, Timothy W.

    2013-01-01

    The partial pressure of oxygen in Earth’s atmosphere has increased dramatically through time, and this increase is thought to have occurred in two rapid steps at both ends of the Proterozoic Eon (∼2.5–0.543 Ga). However, the trajectory and mechanisms of Earth’s oxygenation are still poorly constrained, and little is known regarding attendant changes in ocean ventilation and seafloor redox. We have a particularly poor understanding of ocean chemistry during the mid-Proterozoic (∼1.8–0.8 Ga). G...

  7. Fe-V redox flow batteries

    Science.gov (United States)

    Li, Liyu; Kim, Soowhan; Yang, Zhenguo; Wang, Wei; Zhang, Jianlu; Chen, Baowei; Nie, Zimin; Xia, Guanguang

    2014-07-08

    A redox flow battery having a supporting solution that includes Cl.sup.- anions is characterized by an anolyte having V.sup.2+ and V.sup.3+ in the supporting solution, a catholyte having Fe.sup.2+ and Fe.sup.3+ in the supporting solution, and a membrane separating the anolyte and the catholyte. The anolyte and catholyte can have V cations and Fe cations, respectively, or the anolyte and catholyte can each contain both V and Fe cations in a mixture. Furthermore, the supporting solution can contain a mixture of SO.sub.4.sup.2- and Cl.sup.- anions.

  8. Aqueous electrolytes for redox flow battery systems

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Tianbiao; Li, Bin; Wei, Xiaoliang; Nie, Zimin; Wang, Wei; Liu, Jun; Sprenkle, Vincent L.

    2017-10-17

    An aqueous redox flow battery system includes an aqueous catholyte and an aqueous anolyte. The aqueous catholyte may comprise (i) an optionally substituted thiourea or a nitroxyl radical compound and (ii) a catholyte aqueous supporting solution. The aqueous anolyte may comprise (i) metal cations or a viologen compound and (ii) an anolyte aqueous supporting solution. The catholyte aqueous supporting solution and the anolyte aqueous supporting solution independently may comprise (i) a proton source, (ii) a halide source, or (iii) a proton source and a halide source.

  9. Transition-Metal-Catalyzed Redox-Neutral and Redox-Green C-H Bond Functionalization.

    Science.gov (United States)

    Wang, Hongli; Huang, Hanmin

    2016-08-01

    Transition-metal-catalyzed C-H bond functionalization has become one of the most promising strategies to prepare complex molecules from simple precursors. However, the utilization of environmentally unfriendly oxidants in the oxidative C-H bond functionalization reactions reduces their potential applications in organic synthesis. This account describes our recent efforts in the development of a redox-neutral C-H bond functionalization strategy for direct addition of inert C-H bonds to unsaturated double bonds and a redox-green C-H bond functionalization strategy for realization of oxidative C-H functionalization with O2 as the sole oxidant, aiming to circumvent the problems posed by utilizing environmentally unfriendly oxidants. In principle, these redox-neutral and redox-green strategies pave the way for establishing new environmentally benign transition-metal-catalyzed C-H bond functionalization strategies. © 2016 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Stimulus processing and associative learning in Wistar and WKHA rats.

    Science.gov (United States)

    Chess, Amy C; Keene, Christopher S; Wyzik, Elizabeth C; Bucci, David J

    2005-06-01

    This study assessed basic learning and attention abilities in Wistar-Kyoto hyperactive (WKHA) rats using appetitive conditioning preparations. Two measures of conditioned responding to a visual stimulus, orienting behavior (rearing on the hind legs), and food cup behavior (placing the head inside the recessed food cup) were measured. In Experiment 1, simple conditioning, but not extinction, was impaired in WKHA rats compared with Wistar rats. In Experiment 2, nonreinforced presentations of the visual cue preceded the conditioning sessions. WKHA rats displayed less orienting behavior than Wistar rats but comparable levels of food cup behavior. These data suggest that WKHA rats exhibit specific abnormalities in attentional processing as well as in learning stimulus-reward relationships. (c) 2005 APA, all rights reserved.

  11. Levels of processing and Eye Movements: A Stimulus driven approach

    DEFF Research Database (Denmark)

    Mulvey, Fiona Bríd

    2014-01-01

    movements from the effect of the changing nature of the stimulus is difficult. Characterising and confirming the parameters of levels of processing in eye movements requires measures with the explicit intention of systematically varying task demands while also taking account of individual differences....... This series of studies attempts to provide explanatory information for previous findings that saccade amplitude and fixation duration are indicative of levels of processing and to isolate top down influences on eye movements with a stimulus driven approach. This approach involves developing measures suitable...... to investigate individual differences in levels of processing within the normal population using existing constructs and tests of cognitive style. Study 4 investigates these stimuli and the eye movements of a clinical group with known interruption to the dorsal stream of processing, and subsequent isolated...

  12. Effects of stimulus duration on gustatory evoked potentials

    DEFF Research Database (Denmark)

    Rotvel, Camilla Arndal; Møller, Stine; Kivisaar, Kätlin

    . 19 normal-tasting subjects (10 females, mean age ± sd: 27 ± 3) were stimulated with aqueous 0.5g/L sucralose in between continuous periods of non-chlorinated tap water to avoid somatosensory onsets. The sucralose stimulus duration was either short (~0.6s) or long (~4s) and presented in random...... sucralose stimulation kept the GEP significant for longer and produced a larger peak occurring at ~1.6sec (t-test) while maintaining the characteristic negative temporal deflection as opposed to the short stimulation which produced frontal activity. Instances of brain response to varying NaCl stimulus...... sucralose stimulation duration resulted in larger GEP peak amplitude above the gustatory cortex and may indicate higher intensity perception (Kelling and Halpern, 1988)....

  13. Stimulus determinants of the phenomenon of change blindness

    Directory of Open Access Journals (Sweden)

    Gusev, Alexey N.

    2014-03-01

    Full Text Available This article describes techniques and procedures that are used to research the changeblindness phenomenon. The role of stimulus parameters in completing a visual task (detecting changes was investigated. The following parameters of visual stimuli varied in a chronometric experiment: the number of objects, their location in the stimulus space, and the shape of the objects (including a new object that attracts attention as well as various changes of single objects, such as appearance/disappearance, location shifts, changes of color and shape. The results of this study indicate that change blindness can have a different intensity (the time of detecting changes in flickering images depending on the number of objects, their location in the stimulus space (structured or randomized, and the type of change (the most complicated one was a change of color: 1.The number of objects has considerable influence on the intensity of change blindness and is the most powerful parameter. 2.The shape of the objects within the image is not crucial for change-detection time. 3..The spatial organization of the objects is important for the successful detection of changes. The changes are detected quicker in images with regular rather than random organization. 4.A distraction (in this case, a word that was substituted for an object doesn’t have any considerable influence on change detection. 5.Change-detection time increases as the interstimulus interval increases from 200 to 400 ms. 6.The detection of shifts and of appearance/disappearance is quicker than the detection of color change. These results let us create stimulus patterns for change-blindness experiments that differ in complexity, and thus we could examine a wide range of hypotheses about the function of the psychological mechanisms of spatial attention that are used to explain this phenomenon.

  14. Benzodiazepine-like discriminative stimulus effects of toluene vapor

    Science.gov (United States)

    Shelton, Keith L.; Nicholson, Katherine L.

    2013-01-01

    In vitro studies show that the abused inhalant toluene affects a number of ligand-gated ion channels. The two most consistently implicated of these are γ-aminobutyric acid type A (GABAA) receptors which are positively modulated by toluene and N-methyl-D-aspartate (NMDA) receptors which are negatively modulated by toluene. Behavioral studies also suggest an interaction of toluene with GABAA and/or NMDA receptors but it is unclear if these receptors underlie the abuse-related intoxicating effects of toluene. Seventeen B6SJLF1/J mice were trained using a two-choice operant drug discrimination procedure to discriminate 10 min of exposure to 2000 ppm toluene vapor from 10 min of exposure to air. The discrimination was acquired in a mean of 65 training sessions. The stimulus effects of 2000 ppm toluene vapor were exposure concentration-dependent but rapidly diminished following the cessation of vapor exposure. The stimulus effects of toluene generalized to the chlorinated hydrocarbon vapor perchloroethylene but not 1,1,2-trichloroethane nor the volatile anesthetic isoflurane. The competitive NMDA antagonist CGS-17955, the uncompetitive antagonist dizocilpine and the glycine-site antagonist L701,324 all failed to substitute for toluene. The classical nonselective benzodiazepines midazolam and chlordiazepoxide produced toluene-like stimulus effects but the alpha 1 subunit preferring positive GABAA modulator zaleplon failed to substitute for toluene. The barbiturates pentobarbital and methohexital and the GABAA-positive modulator neurosteroid allopregnanolone did not substitute for toluene. These data suggest that the stimulus effects of toluene may be at least partially mediated by benzodiazepine-like positive allosteric modulation of GABAA receptors containing alpha 2, 3 or 5 subunits. PMID:24436974

  15. Visual Distractors Disrupt Audiovisual Integration Regardless of Stimulus Complexity

    OpenAIRE

    Gibney, Kyla D.; Aligbe, Enimielen; Eggleston, Brady A.; Nunes, Sarah R.; Kerkhoff, Willa G.; Dean, Cassandra L.; Kwakye, Leslie D.

    2017-01-01

    The intricate relationship between multisensory integration and attention has been extensively researched in the multisensory field; however, the necessity of attention for the binding of multisensory stimuli remains contested. In the current study, we investigated whether diverting attention from well-known multisensory tasks would disrupt integration and whether the complexity of the stimulus and task modulated this interaction. A secondary objective of this study was to investigate individ...

  16. Visual hemispatial inattention: stimulus parameters and exploratory strategies.

    OpenAIRE

    Weintraub, S; Mesulam, M.M.

    1988-01-01

    Patients with unilateral hemispheric lesions were given visual target cancellation tasks. As expected, marked contralateral and less severe ipsilateral visual inattention were observed in patients with right-sided cerebral lesions whereas those with left-sided lesions showed only mild contralateral neglect. Stimulus material (shapes vs letters) and array (random vs structured) interacted in a complex manner to influence target detection only in patients with right-sided lesions. Furthermore, ...

  17. Speech Prosody Across Stimulus Types for Individuals with Parkinson's Disease.

    Science.gov (United States)

    K-Y Ma, Joan; Schneider, Christine B; Hoffmann, Rüdiger; Storch, Alexander

    2015-01-01

    Up to 89% of the individuals with Parkinson's disease (PD) experience speech problem over the course of the disease. Speech prosody and intelligibility are two of the most affected areas in hypokinetic dysarthria. However, assessment of these areas could potentially be problematic as speech prosody and intelligibility could be affected by the type of speech materials employed. To comparatively explore the effects of different types of speech stimulus on speech prosody and intelligibility in PD speakers. Speech prosody and intelligibility of two groups of individuals with varying degree of dysarthria resulting from PD was compared to that of a group of control speakers using sentence reading, passage reading and monologue. Acoustic analysis including measures on fundamental frequency (F0), intensity and speech rate was used to form a prosodic profile for each individual. Speech intelligibility was measured for the speakers with dysarthria using direct magnitude estimation. Difference in F0 variability between the speakers with dysarthria and control speakers was only observed in sentence reading task. Difference in the average intensity level was observed for speakers with mild dysarthria to that of the control speakers. Additionally, there were stimulus effect on both intelligibility and prosodic profile. The prosodic profile of PD speakers was different from that of the control speakers in the more structured task, and lower intelligibility was found in less structured task. This highlighted the value of both structured and natural stimulus to evaluate speech production in PD speakers.

  18. Neurogenic vestibular evoked potentials using a tone pip auditory stimulus.

    Science.gov (United States)

    Papathanasiou, E S; Zamba-Papanicolaou, E; Pantziaris, M; Kleopas, K; Kyriakides, T; Papacostas, S; Pattichis, C; Iliopoulos, I; Piperidou, C

    2004-01-01

    To obtain neurogenic vestibular evoked potentials (NVESTEPs) with surface scalp recording using a tone pip auditory stimulus. Fourteen neurologically normal volunteers (Age range 26-45 years, 10 females and 4 males), and two patients with sensorineural hearing loss and possible multiple sclerosis respectively, were examined. Two channel recordings were obtained, the first channel being P3 referred to Fpz, and the second channel being P4 referred to Fpz. A 1 kHz tone pip stimulus with two cycles was delivered via headphones monoaurally with contralateral masking noise. A consistent negative wave with a mean absolute latency of 4.72 msec was obtained, which we have named N5. 25% of the ears tested had better responses at the ipsilateral parietal electrode. In the patient with bilateral sensorineural hearing loss, NVESTEPs was present, suggesting that the NVESTEP is not a cochlear response. In the patient with possible multiple sclerosis, an abnormal NVESTEP response and a normal BAEP response were found. Use of a tone-pip rather than a click auditory stimulus allows a lower click intensity to be used in the production of NVESTEP responses, leads to a shorter testing time, and is therefore more comfortable for the patient. This study adds to our impression that the NVESTEP may be a physiological response that can be used to assess the vestibular system and is different from the BAEP response. Further testing in patients with symptoms of dizziness and with disorders specific for the vestibular nerve is required.

  19. Accommodative Stimulus-Response Curve with Emoji Symbols

    Directory of Open Access Journals (Sweden)

    Robert Montés-Micó

    2017-01-01

    Full Text Available Purpose. To evaluate the static measurement of the accommodative stimulus-response curve with emoji symbols. Methods. The accommodative stimulus-response curve was measured in 18 subjects using a Hartmann-Shack sensor to obtain the objective accommodative response from the Zernike defocus term. Measurements were acquired at different accommodative demands, from 0 to 3 D with a step of 0.5 D. Detailed and nondetailed emoji targets were used with two different sizes, corresponding to the two most common visual angles used in smartphones. Results. A regression analysis was performed to fit the mean results obtained for each target. The determination coefficient was R2≥0.988 for all targets. For the detailed targets, the slopes for the averaged stimulus-response curve were 0.65 and 0.66 for the bigger and smaller sizes, respectively. For the nondetailed targets, the slopes were 0.60 and 0.58 for the bigger and smaller sizes, respectively. p values for these slopes were statistically significant for the two types of targets (p<0.01. Conclusions. Our results reveal that the replacement of a word or several words by detailed or nondetailed emoji symbols seems not to provoke a different accommodative response in normal subjects and under standard viewing conditions in the use of smartphones.

  20. Accommodative Stimulus-Response Curve with Emoji Symbols

    Science.gov (United States)

    Montés-Micó, Robert; Bernal-Molina, Paula; Ferrer-Blasco, Teresa

    2017-01-01

    Purpose To evaluate the static measurement of the accommodative stimulus-response curve with emoji symbols. Methods The accommodative stimulus-response curve was measured in 18 subjects using a Hartmann-Shack sensor to obtain the objective accommodative response from the Zernike defocus term. Measurements were acquired at different accommodative demands, from 0 to 3 D with a step of 0.5 D. Detailed and nondetailed emoji targets were used with two different sizes, corresponding to the two most common visual angles used in smartphones. Results A regression analysis was performed to fit the mean results obtained for each target. The determination coefficient was R2 ≥ 0.988 for all targets. For the detailed targets, the slopes for the averaged stimulus-response curve were 0.65 and 0.66 for the bigger and smaller sizes, respectively. For the nondetailed targets, the slopes were 0.60 and 0.58 for the bigger and smaller sizes, respectively. p values for these slopes were statistically significant for the two types of targets (p emoji symbols seems not to provoke a different accommodative response in normal subjects and under standard viewing conditions in the use of smartphones. PMID:29082040

  1. Discriminative stimulus and antinociceptive effects of dihydroetorphine in rhesus monkeys.

    Science.gov (United States)

    Gerak, Lisa R; Gauthier, Cheryl R A; France, Charles R A P

    2003-04-01

    Although dihydroetorphine has micro opioid agonist activity there is evidence to suggest that it is not identical to that of morphine. This study compared dihydroetorphine to other opioids under behavioral conditions that are sensitive to micro opioid agonism. The acute effects of dihydroetorphine, etorphine and morphine were evaluated using two procedures. In one procedure, monkeys received 3.2 mg/kg per day of morphine and discriminated naltrexone from saline while responding under a fixed-ratio 5 schedule of stimulus shock termination. In addition, a warm-water, tail-withdrawal procedure was used in untreated monkeys. When acutely deprived of morphine, monkeys responded on the naltrexone lever, and this effect was reversed by dihydroetorphine, etorphine and morphine. Each agonist produced the maximum (20-s latency) antinociceptive effect in 50 degrees C water. Naltrexone antagonized the discriminative stimulus and antinociceptive effects of dihydroetorphine and etorphine, although Schild analyses yielded large variability in slopes and pA(2) values. Naltrexone reversed established effects of dihydroetorphine and morphine in both procedures and pretreatment with dihydroetorphine (2, 6 or 24 h) did not alter the discriminative stimulus effects of morphine. Taken together, these data support the notion that dihydroetorphine is a micro agonist with a short duration of action; however, variability in antagonism of dihydroetorphine and morphine might be a manifestation of differences that have been reported for these drugs at the cellular level.

  2. Stimulus characteristics affect assessment of pupil defects in amblyopia.

    Science.gov (United States)

    Law, Cristina Llerena; Siu, Matt; Modica, Patricia; Backus, Benjamin

    2015-05-01

    Amblyopes do not reliably show relative afferent pupillary defects with full-field stimulation, but amblyopia has cortical involvement; hence, stimuli that engage cortex may be able to reveal pupil defects in amblyopes. Pupillary responses were acquired with a binocular infrared pupillometer (RAPDx, Konan Medical USA, Irvine, CA) from 15 amblyopic subjects (anisometropic and small-angle strabismic) and 10 age-matched control subjects. Stimuli were a full-field white flash (330 cd/m) or a small (4 degrees) annulus at one of three contrast levels (0.3, 0.6, and 1.8) on a dim background (6.2 cd/m). Stimulus duration was 100 milliseconds, and the interstimulus duration was 2000 milliseconds. In all four stimulus conditions, the difference in percent contraction amplitude for right versus left eye stimulation was more variable across amblyopes than across control subjects. Amblyopic eyes did not show a specific deficit for the full-field flash. However, the mid-contrast (0.6) annulus stimulus revealed a deficit in the amblyopic eye, whereas the size of the deficit did not correlate with the type or depth of the amblyopia. Targets of appropriate pattern, brightness, and contrast that select for cortical contributions to the pupil response may be useful for eliciting pupil defects in amblyopic patients. Pupil analysis in this population could prove useful for diagnostic or prognostic value, for example, to determine which amblyopes will respond best to treatment.

  3. Evidence for response membership in stimulus classes by pigeons.

    Science.gov (United States)

    Urcuioli, Peter J; Jones, B Max; Lionello-DeNolf, Karen M

    2013-03-01

    Response membership in pigeons' stimulus-class formation was evaluated using associative symmetry and class expansion tests. In Experiment 1, pigeons learned hue-hue (AA) and form-form (BB) successive matching plus a modified hue-form (AB) task in which reinforcement was contingent upon a left versus right side-key response after the positive AB sequences. On subsequent BA (symmetry) probe trials, pigeons responded more often to the comparisons on the reverse of the positive than negative AB sequences and, more importantly, preferentially pecked the side key consistent with symmetry after the reversed positive sequences. In Experiment 2, the original three baseline tasks were supplemented by dot-white (CC) successive matching in which reinforcement was contingent upon a left versus right side-key response after the positive CC sequences. Class expansion was then tested by presenting nonreinforced CA and CB successive matching probes. Comparison response rates were mostly nondifferential on CA probes but were uniformly higher on CB probes that consisted of the C samples and B comparisons from the same, hypothesized class. Together, these results provide evidence that responses can become members of stimulus classes, as predicted by Urcuioli's (2008) theory of pigeons' stimulus-class formation and Sidman's (2000) theory of equivalence. © Society for the Experimental Analysis of Behavior.

  4. The Effect of Stimulus Timing on Unplanned Gait Termination.

    Science.gov (United States)

    Ohm, Kelly; Hahn, Michael E

    2016-08-01

    Gait termination can be challenging for balance-impaired populations, including lower limb amputees. As powered prosthetic ankle devices come to market, it is important to better understand gait termination timing in an unplanned situation. Timing patterns were examined in unplanned gait termination to determine a threshold for being able to terminate gait in 1 step. Time to terminate gait (TTG) was also examined, using both final heel strike and center of mass (COM) acceleration metrics. Fourteen able-bodied subjects walked over ground and terminated gait in response to a randomly-timed auditory stimulus. A lumbar-mounted accelerometer and footswitches were used to assess timing of gait termination. Subjects were able to terminate gait in 1 step if the stimulus occurred at or before 19.8% of gait cycle. Later stimulus resulted in a 2-step stop pattern. The TTG using COM acceleration was greater than when using heel strike data. Motion of the COM was not fully arrested until 162 ± 38% of gait cycle. The stabilization phase between heel strike and COM motion arrest was greater for 1-step stops (1.41 ± 0.42 s) than 2-step stops (0.96 ± 0.33 s). These findings indicate gait termination timing should be calculated using COM motion, including the stabilization phase post heel strike.

  5. High Stimulus-Related Information in Barrel Cortex Inhibitory Interneurons.

    Directory of Open Access Journals (Sweden)

    Vicente Reyes-Puerta

    2015-06-01

    Full Text Available The manner in which populations of inhibitory (INH and excitatory (EXC neocortical neurons collectively encode stimulus-related information is a fundamental, yet still unresolved question. Here we address this question by simultaneously recording with large-scale multi-electrode arrays (of up to 128 channels the activity of cell ensembles (of up to 74 neurons distributed along all layers of 3-4 neighboring cortical columns in the anesthetized adult rat somatosensory barrel cortex in vivo. Using two different whisker stimulus modalities (location and frequency we show that individual INH neurons--classified as such according to their distinct extracellular spike waveforms--discriminate better between restricted sets of stimuli (≤6 stimulus classes than EXC neurons in granular and infra-granular layers. We also demonstrate that ensembles of INH cells jointly provide as much information about such stimuli as comparable ensembles containing the ~20% most informative EXC neurons, however presenting less information redundancy - a result which was consistent when applying both theoretical information measurements and linear discriminant analysis classifiers. These results suggest that a consortium of INH neurons dominates the information conveyed to the neocortical network, thereby efficiently processing incoming sensory activity. This conclusion extends our view on the role of the inhibitory system to orchestrate cortical activity.

  6. Iron content of soils as a precipitation proxy

    Science.gov (United States)

    Dzombak, R.; Sheldon, N. D.

    2016-12-01

    Given that different iron phases form under different precipitation and drainage regimes, soil iron content could be used as a proxy for both volume and seasonality of precipitation. Constraining these factors is important for predicting future precipitation trends, especially for a warmer climate that will likely see more frequent extreme weather events. Specifically, using paleoprecipitation data from periods of higher temperatures and atmospheric CO2 concentrations helps inform models of future `greenhouse' climate. Forty-five modern samples from across the continental United States were analyzed, with MAP ranging from 200 to 1200 mm yr-1 and MAT ranging from 5 to 22°C. Soil types included Alfisols (N=15), Inceptisols (N=8), Mollisols (N=15), and Aridisols (N=7), and ranged from seasonally wet to well-drained. Analytical techniques included combustion-elemental analysis and organic carbon isotope analysis, a sequential iron extraction modified with a sodium hypochlorite step for the extraction of organic matter-bound iron, and the extraction of iron sulfides. The sequential extractions yield five different `pools' of iron found in sediment: crystalline iron oxides (e.g., goethite, hematite), magnetite, carbonate-bound, organic matter-bound, and labile/easily reducible iron minerals (e.g., ferrihydrite). Analysis by ICP-OES yielded a strong relationship between magnetite-bound iron and MAP, and fair relationships between the other iron pools and MAP. Individual soil orders tended to show stronger relationships to the iron pools than all soils analyzed together, potentially indicating the need for separate proxy relationships for each soil order. Pyrite concentrations were well below 1% by weight for these soils, suggesting that none of these soils has a long enough wet season to encourage its formation and that the presence vs. absence of pyrite in paleosols may be a useful proxy for soil moisture state. In contrast to some earlier work, no significant

  7. Carbohydrates and phenols as quantitative molecular vegetation proxies in peats

    Science.gov (United States)

    Kaiser, K.; Benner, R. H.

    2012-12-01

    Vegetation in peatlands is intricately linked to local environmental conditions and climate. Here we use chemical analyses of carbohydrates and phenols to reconstruct paleovegetation in peat cores collected from 56.8°N (SIB04), 58.4°N (SIB06), 63.8°N (G137) and 66.5°N (E113) in the Western Siberian Lowland. Lignin phenols (vanillyl and syringyl phenols) were sensitive biomarkers for vascular plant contributions and provided additional information on the relative contributions of angiosperm and gymnosperm plants. Specific neutral sugar compositions allowed identification of sphagnum mosses, sedges (Cyperaceae) and lichens. Hydroxyphenols released by CuO oxidation were useful tracers of sphagnum moss contributions. The three independent molecular proxies were calibrated with a diverse group of peat-forming plants to yield quantitative estimates (%C) of vascular plant, sphagnum moss and lichen contributions in peat core samples. Correlation analysis indicated the three molecular proxies produced fairly similar results for paleovegetation compositions, generally within the error interval of each approach (≤26%). The lignin-based method generally lead to higher estimates of vascular plant vegetation. Several significant deviations were also observed due to different reactivities of carbohydrate and phenolic polymers during peat decomposition. Rapid vegetation changes on timescales of 50-200 years were observed in the southern cores SIB04 and SIB06 over the last 2000 years. Vanillyl and syringyl phenol ratios indicated these vegetation changes were largely due to varying inputs of angiosperm and gymnosperm plants. The northern permafrost cores G137 and E113 showed a more stable development. Lichens briefly replaced sphagnum mosses and vascular plants in both of these cores. Shifts in vegetation did not correlate well with Northern hemisphere climate variability over the last 2000 years. This suggested that direct climate forcing of peatland dynamics was overridden

  8. Analysis of Forgery Attack on One-Time Proxy Signature and the Improvement

    Science.gov (United States)

    Wang, Tian-Yin; Wei, Zong-Li

    2016-02-01

    In a recent paper, Yang et al. (Quant. Inf. Process. 13(9), 2007-2016, 2014) analyzed the security of one-time proxy signature scheme Wang and Wei (Quant. Inf. Process. 11(2), 455-463, 2012) and pointed out that it cannot satisfy the security requirements of unforgeability and undeniability because an eavesdropper Eve can forge a valid proxy signature on a message chosen by herself. However, we find that the so-called proxy message-signature pair forged by Eve is issued by the proxy signer in fact, and anybody can obtain it as a requester, which means that the forgery attack is not considered as a successful attack. Therefore, the conclusion that this scheme cannot satisfy the security requirements of proxy signature against forging and denying is not appropriate in this sense. Finally, we study the reason for the misunderstanding and clarify the security requirements for proxy signatures.

  9. Redox Reaction Mechanisms with Non-triiodide Mediators in Dye-Sensitized Solar Cells by Redox Potential Calculations.

    Science.gov (United States)

    Jono, Ryota; Sumita, Masato; Tateyama, Yoshitaka; Yamashita, Koichi

    2012-12-06

    We investigate reaction mechanisms of the redox mediators in dye-sensitized solar cells through systematic calculations of redox potentials of possible cobalt complexes and iodides in acetonitrile solution by use of the thermodynamic cycle method with continuum solvent model. The calculated redox potentials were in good agreement with the experimental values, although the experimentalists used different reference electrodes. The maximum open circuit voltage (VOC) of the mediators calculated in this work indicate that the I2(•-)/2I(-) and I2/I2(•-) as well as the net I2/2I(-) redox reactions can dominate at both photoanode and counter-electrode.

  10. Mineral evolution of redox-sensitive elements

    Science.gov (United States)

    Hazen, R. M.; Sverjensky, D. A.; Grew, E. S.; Downs, R. T.; Golden, J.; Hystad, G.

    2012-12-01

    Temporal trends in Earth's near-surface mineralogy correlate with major events in geochemical, tectonic, and biological evolution. Recent compilations of age and locality information for the minerals of redox-sensitive elements Mo, Hg, W, Ni, Co, and U reveal statistically significant trends related to key events in the history of the geosphere and biosphere. Mineralization for all of these elements correlates with five intervals of supercontinent assembly, from ~2.7 Ga (Kenorland) to 300 Ma (Pangaea; see Fig. 1). Details of mineral diversity and distribution correlate with changes in near-surface geochemistry, as well as such biological innovations as oxygenic photosynthesis and the rise of the terrestrial biosphere. In addition, systematic increases in average and maximum trace concentrations of Re in molybdenite since 3.0 Ga point to enhanced oxidative weathering by subsurface fluids (Fig. 2). These trace element results, coupled with the delayed appearance of minerals of other redox sensitive elements, suggest that significant terrestrial subsurface oxidation may have postdated the Great Oxidation Event (~2.4 to 2.2 Ga) by hundreds of millions of years.he distribution of molybdenite (MoS2) through Earth history is episodic, with maxima corresponding to times of supercontinent assembly. he rhenium content of molybdenite displays a statistically significant increase over 3 billion years of Earth history. This trend reflects the increased mobility of Re in more oxidized subsurface aqueous environments.

  11. Redox characterization of functioning skeletal muscle

    Directory of Open Access Journals (Sweden)

    Li eZuo

    2015-11-01

    Full Text Available Skeletal muscle physiology is influenced by the presence of chemically reactive molecules such as reactive oxygen species (ROS. These molecules regulate multiple redox-sensitive signaling pathways that play a critical role in cellular processes including gene expression and protein modification. While ROS have gained much attention for their harmful effects in muscle fatigue and dysfunction, research has also shown ROS to facilitate muscle adaptation after stressors such as physical exercise. This manuscript aims to provide a comprehensive review of the current understanding of redox signaling in skeletal muscle. ROS-induced oxidative stress and its role in the aging process are discussed. Mitochondria have been shown to generate large amounts of ROS during muscular contractions, and thus are susceptible to oxidative stress. ROS can modify proteins located in the mitochondrial membrane leading to cell death and osmotic swelling. ROS also contribute to the necrosis and inflammation of muscle fibers that is associated with muscular diseases including Duchenne muscular dystrophy (DMD. It is imperative that future research continues to investigate the exact role of ROS in normal skeletal muscle function as well as muscular dysfunction and disease.

  12. Salt stress affects the redox status of Arabidopsis root meristems

    Directory of Open Access Journals (Sweden)

    Keni eJiang

    2016-02-01

    Full Text Available We report the redox status (profiles for specific populations of cells that comprise the Arabidopsis root tip. For recently germinated, 3-5-day-old seedlings we show that the region of the root tip with the most reduced redox status includes the root cap initials, the quiescent center and the most distal portion of the proximal meristem, and coincides with (overlays the region of the auxin maximum. As one moves basally, further into the proximal meristem, and depending on the growth conditions, the redox status becomes more oxidized, with a 5-10 mV difference in redox potential between the two borders delimiting the proximal meristem. At the point on the root axis at which cells of the proximal meristem cease division and enter the transition zone, the redox potential levels off and remains more or less unchanged throughout the transition zone. As cells leave the transition zone and enter the zone of elongation the redox potentials become more oxidized. Treating roots with salt (50, 100 and 150 mM NaCl results in marked changes in root meristem structure and development, and is preceded by changes in the redox profile, which flattens, and initially becomes more oxidized, with pronounced changes in the redox potentials of the root cap, the root cap initials and the quiescent center. Roots exposed to relatively mild levels of salt (< 100 mM are able to re-establish a normal, pre-salt treatment redox profile 3-6 days after exposure to salt. Coincident with the salt-associated changes in redox profiles are changes in the distribution of auxin transporters (AUX1, PIN1/2, which become more diffuse in their localization. We conclude that salt stress affects root meristem maintenance, in part, through changes in redox and auxin transport.

  13. MANFAAT STIMULUS VERTEBRA CERVIKALIS KE 5-6 DAN STIMULUS OTOT RECTUS ABDOMINIS TERHADAP PERUBAHAN TFU IBU POST PARTUM PER VAGINAM

    Directory of Open Access Journals (Sweden)

    Suryanti Suryanti

    2017-02-01

    Full Text Available Latar Belakang : Involusi uterus merupakan proses normal pada masa nifas dan dimulai segera setelah plasenta lahir akibat kontraksi otot-otot polos uterus. Stimulus adalah perangsang organism tubuh atau reseptor lain untuk menjadi aktif. Pemberian stimulus Vertebra Cervikal dapat merangsang hipofisis anterior dan posterior untuk mengeluarkan hormon oksitosin. Hormon oksitosin akan memicu kontraksi otot polos pada uterus. Tujuan : Penelitian ini bertujuan untuk manfaat stimulus vertebra cervikalis ke 5-6 dan stimulus otot rectus abdominis terhadap perubahan tfu ibu post partum pervaginam. Metode: Populasi dan sampel dalam penelitian ini adalah ibu postpartum pervaginam di Ruang Nifas RSUD Dr. Soeselo Slawi. penelitian ini menggunakan t-test of relate. Hasil : Dalam uji hipotesis didapatkan t hitung ? t table (10.863 ? 1.980, maka dapat disimpulkan Ho ditolak dan Ha diterima. Kesimpulan : Artinya terdapat manfaat stimulus vertebra cervikalis ke 5-6 dan stimulus otot rectus abdominis terhadap perubahan tinggi fundus uteri ibu postpartum pervaginam.

  14. Law Enforcement Proxies Matter for the Law and Finance Nexus

    Directory of Open Access Journals (Sweden)

    Valentin Toci

    2013-07-01

    Full Text Available The paper employs various measures of law enforcement to provide new evidence on the importance of legal institutions for different dimensions of financial development in transition economies. It offers a critical assessment of law enforcement measures employed in recent studies by showing that some proxies for law enforcement in the credit market may not be appropriate. Hence, care should be taken in how the quality of institutions is measured and the context which it represents. An original approach to measuring law enforcement in the credit market is developed by embodying the legal theory of dispute resolution and assessing this approach by collecting primary data for Kosovo. The findings suggest that Kosovo compares well with countries in the region and other transition economies in terms of the enforcement of creditor rights.

  15. Munchausen Syndrome by proxy: Definition, context, and psychological factors involved

    Directory of Open Access Journals (Sweden)

    Thomas Gomes Gonçalves

    2014-07-01

    Full Text Available The Munchausen syndrome by proxy refers to a pathology characterized by physical and emotional abuse in which the simulation or production of symptoms is directed towards a child, which involves taking him or her to health treatments and unnecessary surgeries. The difficulties in the diagnosis of this form of abuse and the emotional aspects involved highlight the destructive effects in the infancy subjectivity due to the lack of loving capacity protecting and prioritizing the child demands. Psychoanalysis offers a differentiated view, comprehending that the mother attempts to elaborate her own psychic conflicts by the repetition of traumatic experience. There is a necessity of comprehension of the instinct destructivity presented in the maternal unconscious dynamics revealed in the modality of caring which is reflected in violence.

  16. Obesity as a Presentation of Munchausen Syndrome by Proxy.

    Science.gov (United States)

    Nogueira-de-Almeida, Carlos Alberto; de Almeida, Carla Cristina J N; Pereira, Natália Inocêncio; de Souza Filho, Nilton Antonio; de Oliveira, Valmir Aparecido

    2017-04-17

    To describe a case of an obese child whose weight gain was related to the Munchausen Syndrome by proxy (MSP). This is a case report including information regarding the child's clinical history and the mother's behavior. The common features of the syndrome are confronted with the description of the case, seeking to demonstrate the similarities. The description ratifies the diagnosis based on the signs and symptoms presented by the child (<5 years old, frequent contacts with health system, symptoms witnessed only by the mother, confusing findings, not helped by treatments, emotionally distant father) and the attitude of the mother (concerned, interested in procedures, comfortable in the medical setting, higher medical knowledge, hostile when thwarted). The case presented points to a new etiology, the MSP, to be considered within the set of factors currently known to cause and maintain obesity in childhood.

  17. Interactive images: Cuboid proxies for smart image manipulation

    KAUST Repository

    Zheng, Youyi

    2012-07-01

    Images are static and lack important depth information about the underlying 3D scenes. We introduce interactive images in the context of man-made environments wherein objects are simple and regular, share various non-local relations (e.g., coplanarity, parallelism, etc.), and are often repeated. Our interactive framework creates partial scene reconstructions based on cuboid-proxies with minimal user interaction. It subsequently allows a range of intuitive image edits mimicking real-world behavior, which are otherwise difficult to achieve. Effectively, the user simply provides high-level semantic hints, while our system ensures plausible operations by conforming to the extracted non-local relations. We demonstrate our system on a range of real-world images and validate the plausibility of the results using a user study. © 2012 ACM 0730-0301/2012/08-ART99.

  18. Reliability of proxy reports of parental smoking by elementary schoolchildren.

    Science.gov (United States)

    Barnett, T; O'Loughlin, J; Paradis, G; Renaud, L

    1997-08-01

    To investigate the reliability of reports of parental smoking by elementary schoolchildren aged 9-13 years, and to identify the correlates of disagreement between student proxy and parent self-reports. As part of the evaluation of a school-based heart health promotion program, data on parental smoking status were collected from 1240 student-mother pairs and 898 student-father pairs. Agreement for parental smoking status was 93.1% among student-mother pairs and 86.4% among student-father pairs. Among student-mother pairs, reports by students aged 9 years were more likely to disagree with mothers' self-reports than those of older children (odds ratio (OR) = 3.1). Among student-father pairs, the only significant correlate of disagreement was living in a single-parent family headed by the mother (OR = 2.6). Children 10-years or older can provide reliable reports of the smoking status of cohabiting parents.

  19. STRONTIUM DISTRIBUTION IN UPPER DEVONIAN CONODONT ELEMENTS: A PALAEOBIOLOGICAL PROXY

    Directory of Open Access Journals (Sweden)

    ANDREY V. ZHURAVLEV

    2017-04-01

    Full Text Available Conodonts are an extinct group of marine animals possessing debated affinities. The conodont elements are composed of calcium phosphate [apatite (CaF] and collagen-like proteins. Distribution of Sr in the bioapatite of albid, lamellar and paralamellar tissues of some Upper Devonian conodont element crowns from NW Russia was studied by microprobe. The calcium phosphate of the lamellar and paralamellar tissues demonstrates periodical oscillation of Sr contents across the lamellae (0.4-0.5 wt% in the outer part of lamella, and 0.2 wt% in the inner part. The albid tissue contains Sr of less than 0.4 wt%. It is suggested that oscillations of Sr concentrations reflect the periodic growth of the lamellae, and the average Ca/Sr ratio can be a proxy of the growth rate.

  20. One thousand years of fires: Integrating proxy and model data

    Directory of Open Access Journals (Sweden)

    Natalie Marie Kehrwald

    2016-04-01

    Full Text Available The current fires raging across Indonesia are emitting more carbon than the annual fossil fuel emissions of Germany or Japan, and the fires are still consuming vast tracts of rainforest and peatlands. The National Interagency Fire Center (www.nifc.gov notes that 2015 is one worst fire years on record in the U.S., where more than 9 million acres burned -- equivalent to the combined size of Massachusetts and New Jersey. The U.S. and Indonesian fires have already displaced tens of thousands of people, and their impacts on ecosystems are still unclear. In the case of Indonesia, the burning peat is destroying much of the existing soil, with unknown implications for the type of vegetation regrowth. Such large fires result from a combination of fire management practices, increasing anthropogenic land use, and a changing climate. The expected increase in fire activity in the upcoming decades has led to a surge in research trying to understand their causes, the factors that may have influenced similar times of fire activity in the past, and the implications of such fire activity in the future. Multiple types of complementary data provide information on the impacts of current fires and the extent of past fires. The wide array of data encompasses different spatial and temporal resolutions (Figure 1 and includes fire proxy information such as charcoal and tree ring fire scars, observational records, satellite products, modern emissions data, fire models within global land cover and vegetation models, and sociodemographic data for modeling past human land use and ignition frequency. Any single data type is more powerful when combined with another source of information. Merging model and proxy data enables analyses of how fire activity modifies vegetation distribution, air and water quality, and proximity to cities; these analyses in turn support land management decisions relating to conservation and development.

  1. Assessing paleo-biodiversity using low proxy influx.

    Directory of Open Access Journals (Sweden)

    Olivier Blarquez

    Full Text Available We developed an algorithm to improve richness assessment based on paleoecological series, considering sample features such as their temporal resolutions or their volumes. Our new method can be applied to both high- and low-count size proxies, i.e. pollen and plant macroremain records, respectively. While pollen generally abounds in sediments, plant macroremains are generally rare, thus leading to difficulties to compute paleo-biodiversity indices. Our approach uses resampled macroremain influxes that enable the computation of the rarefaction index for the low influx records. The raw counts are resampled to a constant resolution and sample volume by interpolating initial sample ages at a constant time interval using the age∼depth model. Then, the contribution of initial counts and volume to each interpolated sample is determined by calculating a proportion matrix that is in turn used to obtain regularly spaced time series of pollen and macroremain influx. We applied this algorithm to sedimentary data from a subalpine lake situated in the European Alps. The reconstructed total floristic richness at the study site increased gradually when both pollen and macroremain records indicated a decrease in relative abundances of shrubs and an increase in trees from 11,000 to 7,000 cal BP. This points to an ecosystem change that favored trees against shrubs, whereas herb abundance remained stable. Since 6,000 cal BP, local richness decreased based on plant macroremains, while pollen-based richness was stable. The reconstructed richness and evenness are interrelated confirming the difficulty to distinguish these two aspects for the studies in paleo-biodiversity. The present study shows that low-influx bio-proxy records (here macroremains can be used to reconstruct stand diversity and address ecological issues. These developments on macroremain and pollen records may contribute to bridge the gap between paleoecology and biodiversity studies.

  2. Assessing paleo-biodiversity using low proxy influx.

    Science.gov (United States)

    Blarquez, Olivier; Finsinger, Walter; Carcaillet, Christopher

    2013-01-01

    We developed an algorithm to improve richness assessment based on paleoecological series, considering sample features such as their temporal resolutions or their volumes. Our new method can be applied to both high- and low-count size proxies, i.e. pollen and plant macroremain records, respectively. While pollen generally abounds in sediments, plant macroremains are generally rare, thus leading to difficulties to compute paleo-biodiversity indices. Our approach uses resampled macroremain influxes that enable the computation of the rarefaction index for the low influx records. The raw counts are resampled to a constant resolution and sample volume by interpolating initial sample ages at a constant time interval using the age∼depth model. Then, the contribution of initial counts and volume to each interpolated sample is determined by calculating a proportion matrix that is in turn used to obtain regularly spaced time series of pollen and macroremain influx. We applied this algorithm to sedimentary data from a subalpine lake situated in the European Alps. The reconstructed total floristic richness at the study site increased gradually when both pollen and macroremain records indicated a decrease in relative abundances of shrubs and an increase in trees from 11,000 to 7,000 cal BP. This points to an ecosystem change that favored trees against shrubs, whereas herb abundance remained stable. Since 6,000 cal BP, local richness decreased based on plant macroremains, while pollen-based richness was stable. The reconstructed richness and evenness are interrelated confirming the difficulty to distinguish these two aspects for the studies in paleo-biodiversity. The present study shows that low-influx bio-proxy records (here macroremains) can be used to reconstruct stand diversity and address ecological issues. These developments on macroremain and pollen records may contribute to bridge the gap between paleoecology and biodiversity studies.

  3. Intensity modulated neutron radiotherapy optimization by photon proxy.

    Science.gov (United States)

    Snyder, Michael; Hammoud, Ahmad; Bossenberger, Todd; Spink, Robyn; Burmeister, Jay

    2012-08-01

    Introducing intensity modulation into neutron radiotherapy (IMNRT) planning has the potential to mitigate some normal tissue complications seen in past neutron trials. While the hardware to deliver IMNRT plans has been in use for several years, until recently the IMNRT planning process has been cumbersome and of lower fidelity than conventional photon plans. Our in-house planning system used to calculate neutron therapy plans allows beam weight optimization of forward planned segments, but does not provide inverse optimization capabilities. Commercial treatment planning systems provide inverse optimization capabilities, but currently cannot model our neutron beam. We have developed a methodology and software suite to make use of the robust optimization in our commercial planning system while still using our in-house planning system to calculate final neutron dose distributions. Optimized multileaf collimator (MLC) leaf positions for segments designed in the commercial system using a 4 MV photon proxy beam are translated into static neutron ports that can be represented within our in-house treatment planning system. The true neutron dose distribution is calculated in the in-house system and then exported back through the MATLAB software into the commercial treatment planning system for evaluation. The planning process produces optimized IMNRT plans that reduce dose to normal tissue structures as compared to 3D conformal plans using static MLC apertures. The process involves standard planning techniques using a commercially available treatment planning system, and is not significantly more complex than conventional IMRT planning. Using a photon proxy in a commercial optimization algorithm produces IMNRT plans that are more conformal than those previously designed at our center and take much less time to create. The planning process presented here allows for the optimization of IMNRT plans by a commercial treatment planning optimization algorithm, potentially allowing

  4. Proxy-assisted multicasting of video streams over mobile wireless networks

    Science.gov (United States)

    Nguyen, Maggie; Pezeshkmehr, Layla; Moh, Melody

    2005-03-01

    This work addresses the challenge of providing seamless multimedia services to mobile users by proposing a proxy-assisted multicast architecture for delivery of video streams. We propose a hybrid system of streaming proxies, interconnected by an application-layer multicast tree, where each proxy acts as a cluster head to stream out content to its stationary and mobile users. The architecture is based on our previously proposed Enhanced-NICE protocol, which uses an application-layer multicast tree to deliver layered video streams to multiple heterogeneous receivers. We targeted the study on placements of streaming proxies to enable efficient delivery of live and on-demand video, supporting both stationary and mobile users. The simulation results are evaluated and compared with two other baseline scenarios: one with a centralized proxy system serving the entire population and one with mini-proxies each to serve its local users. The simulations are implemented using the J-SIM simulator. The results show that even though proxies in the hybrid scenario experienced a slightly longer delay, they had the lowest drop rate of video content. This finding illustrates the significance of task sharing in multiple proxies. The resulted load balancing among proxies has provided a better video quality delivered to a larger audience.

  5. Analisis Perbandingan Respons Time Squid Proxy Pada Windows Server dan Linux Server

    OpenAIRE

    Sirait, Parulian

    2016-01-01

    In the development of information technology, information is obtained quickly through technology computer network known as the Internet. The use bandwidth for Internet access can be maximized by using a proxy server. One of the proxy server is squid. The use squid as the proxy server need to consider the operating system on the server and have not known its best performance on any operating system yet. For that it is necessary to analyze the performance of squid proxy server on a different op...

  6. Investigating the impacts of deep ocean euxinia on continental shelf environments during the Great Ordovician Biodiversification Event: did changes in global oceanic redox have any effect?

    Science.gov (United States)

    Marenco, P. J.; Marenco, K. N.; Phillips, D. E.; Garcia, E.; Toure, N.; Fullem, A.

    2013-12-01

    The Great Ordovician Biodiversification Event was one of the most important radiations in the history of animal life. In particular, the GOBE was characterized by pronounced increases in diversity within the Paleozoic and Modern Evolutionary Faunas (e.g., Droser and Finnegan, 2003). Rather than being attributable to a singular cause, a number of tectonic, ecologic, and climate-related factors are thought to have contributed to this biodiversification event (e.g., Servais et al., 2009). For example, continental shelf area during the GOBE was more extensive than at any other time during the Phanerozoic, and the availability of these warm, shallow-water, well-oxygenated environments likely influenced the radiation (e.g., Servais et al., 2009). Despite this evidence for favorable conditions, recent geochemical studies suggest that the early Paleozoic, including the Ordovician, was a time of episodic deep ocean euxinia (e.g., Gill et al., 2011, Thompson and Kah, 2012). It remains unclear how the hypothesized deep ocean euxinia may have affected the GOBE. For example, it is possible that episodic incursions of euxinic deep water onto the continental shelves may have acted to slow down the GOBE or even dampen its magnitude. On the other hand, such incursions may have accelerated the radiation by adding additional selection pressures to communities that were already adapting to new predation and substrate conditions. Alternatively, the GOBE may have proceeded without any incursions of euxinic deep water onto the continental shelves. One way to address this issue is to investigate short-term, localized redox changes in shallow marine settings. Here we present results from our ongoing investigation of redox changes in shallow-water environments from the Lower and Middle Ordovician of Utah. Specifically, we use abundances of total organic carbon (TOC) and total sulfur (TS) as localized redox proxies. We use the isotopic composition of carbonate associated sulfate (δ34SCAS

  7. Stimulus-Seeking, Extraversion, and Neuroticism in Regular, Occasional, and Non-Exercisers.

    Science.gov (United States)

    Burgess, Sharon S.; Pargman, David

    To test the hypothesis that stimulus-seeking and extraversion underlie "exercise addiction" and sport involvement, the relationships among stimulus-seeking, extraversion, and exercise frequency were examined in ninety males matched on age and educational level. The Stimulus Variation Seeking Scale, Sensation-Seeking Scale (SSS) and…

  8. Distortions of temporal integration and perceived order caused by the interplay between stimulus contrast and duration

    NARCIS (Netherlands)

    Akyürek, Elkan G.; de Jong, Ritske

    2017-01-01

    Stimulus contrast and duration effects on visual temporal integration and order judgment were examined in a unified paradigm. Stimulus onset asynchrony was governed by the duration of the first stimulus in Experiment 1, and by the interstimulus interval in Experiment 2. In Experiment 1, integration

  9. Additive Effects of Stimulus Quality and Word Frequency on Eye Movements during Chinese Reading

    Science.gov (United States)

    Liu, Pingping; Li, Xingshan; Han, Buxin

    2015-01-01

    Eye movements of Chinese readers were recorded for sentences in which high- and low-frequency target words were presented normally or with reduced stimulus quality in two experiments. We found stimulus quality and word frequency produced strong additive effects on fixation durations for target words. The results demonstrate that stimulus quality…

  10. "JCE" Classroom Activity #111: Redox Reactions in Three Representations

    Science.gov (United States)

    Nieves, Edgardo L. Ortiz; Barreto, Reizelie; Medina, Zuleika

    2012-01-01

    This activity introduces students to the concept of reduction-oxidation (redox) reactions. To help students obtain a thorough understanding of redox reactions, the concept is explored at three levels: macroscopic, submicroscopic, and symbolic. In this activity, students perform hands-on investigations of the three levels as they work at different…

  11. Redox zones of a landfill leachate pollution plume (Vejen, Denmark)

    DEFF Research Database (Denmark)

    Lyngkilde, John; Christensen, Thomas Højlund

    1992-01-01

    , ferrogenic, nitrate-reducing and aerobic environments overa distance of 370 m. This redox zone sequence is consistent with thermodynamical principles and is closely matched by the leachate plume determined by the chloride plume distribution. The redox zone sequence is believed to be key in controlling...... the fate of reactive pollutants leached from the landfill....

  12. Biogeochemical Barriers: Redox Behavior of Metals and Metalloids

    Science.gov (United States)

    Wilkin, R. T.

    2008-12-01

    Redox conditions and pH are arguably the most important geochemical parameters that control contaminant transport and fate in groundwater systems. Oxidation-reduction (redox) reactions mediate the chemical behavior of both inorganic and organic chemical constituents by affecting solubility, reactivity, and bioavailability. In recent years, innovative technologies have emerged to meet groundwater cleanup goals that take advantage of the redox behavior of contaminant species. Remedial technologies that strategically manipulate subsurface redox conditions may emphasize reductive processes, as in subsurface permeable reactive barriers, or, oxidative processes, as in permanganate injection. The speciation and mobility of inorganic contaminants can be directly impacted by redox conditions (e.g., As, Se) or can be indirectly tied to redox conditions in cases where complexation or metal precipitation (e.g., Pb, Cd, Ni) occurs with some other redox-sensitive element (e.g., S). Monitoring oxidation-reduction processes in groundwater systems is frequently challenging and should be viewed as an integrated assessment of hydrogeochemical processes, microbiological diversity, and aquifer characteristics. The presentation will discuss approaches for linking field data and geochemical models. A case study site with over two decades of groundwater monitoring data will also be used to explore the contrasting redox behaviors of metals (Pb, Cd) and selected oxyanion species (As, Se). This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.

  13. Investigation of activity and selectivity of redox catalysts in oxidative ...

    African Journals Online (AJOL)

    In this study, oxidative coupling of methane on Redox catalysts in fluidized bed reactor was investigated. For this purpose, the catalyst Mn-Na2WO4/SiO2 was selected as a Redox catalyst. In order to investigate this catalyst, transient state experiments were designed and performed. Then, the different reaction conditions on ...

  14. Exercise redox biochemistry: Conceptual, methodological and technical recommendations

    Directory of Open Access Journals (Sweden)

    James N. Cobley

    2017-08-01

    Full Text Available Exercise redox biochemistry is of considerable interest owing to its translational value in health and disease. However, unaddressed conceptual, methodological and technical issues complicate attempts to unravel how exercise alters redox homeostasis in health and disease. Conceptual issues relate to misunderstandings that arise when the chemical heterogeneity of redox biology is disregarded: which often complicates attempts to use redox-active compounds and assess redox signalling. Further, that oxidised macromolecule adduct levels reflect formation and repair is seldom considered. Methodological and technical issues relate to the use of out-dated assays and/or inappropriate sample preparation techniques that confound biochemical redox analysis. After considering each of the aforementioned issues, we outline how each issue can be resolved and provide a unifying set of recommendations. We specifically recommend that investigators: consider chemical heterogeneity, use redox-active compounds judiciously, abandon flawed assays, carefully prepare samples and assay buffers, consider repair/metabolism, use multiple biomarkers to assess oxidative damage and redox signalling.

  15. Two Ideas of the Redox Reaction: Misconceptions and their ...

    African Journals Online (AJOL)

    For redox reactions students are doing this too: “one Cu2+ ion takes two electrons and is reduced to copper” – instead of “to one Cu atom”! Another difficulty seems to be the historical redox definition with the “oxygen transfer”: this idea is so attractive that students argue mostly with oxygen participation instead of the transfer ...

  16. Redox properties of extracellular polymeric substances (EPS) from electroactive bacteria.

    Science.gov (United States)

    Li, Shan-Wei; Sheng, Guo-Ping; Cheng, Yuan-Yuan; Yu, Han-Qing

    2016-12-19

    Although the capacity for electroactive bacteria to convert environmental metallic minerals and organic pollutants is well known, the role of the redox properties of microbial extracellular polymeric substances (EPS) in this process is poorly understood. In this work, the redox properties of EPS from two widely present electroactive bacterial strains (Shewanella oneidensis and Pseudomonas putida) were explored. Electrochemical analysis demonstrates that the EPS extracted from the two strains exhibited redox properties. Spectroelectrochemical and protein electrophoresis analyses indicate that the extracted EPS from S. oneidensis and P. putida contained heme-binding proteins, which were identified as the possible redox components in the EPS. The results of heme-mediated behavior of EPS may provide an insight into the important roles of EPS in electroactive bacteria to maximize their redox capability for biogeochemical cycling, environmental bioremediation and wastewater treatment.

  17. Development of redox stable, multifunctional substrates for anode supported SOFCS

    DEFF Research Database (Denmark)

    Sudireddy, Bhaskar Reddy; Foghmoes, Søren Preben Vagn; Ramos, Tania

    2017-01-01

    Redox stable solid oxide fuel cells are beneficial in many aspects such as tolerance against system failures e.g fuel cut off and emergency shut down, but also allow for higher fuel utilization, which increases efficiency. State-ofthe-art Ni-cermet based anodes suffer from microstructural changes...... with a multifunctional anode support, the development of a two layer fuel electrode based on a redox stable strontium titanate layer for the electrochemically active layer and a redox stable Ni-YSZ support was pursued. Half-cells with well adhearing strontium titante anode layers on stateof-the-art Ni-YSZ cermet...... supports have been achieved. Redox tolerance of the half-cell depends could be increased by optimizing the redox stability of the cermet support....

  18. Measuring intracellular redox conditions using GFP-based sensors

    DEFF Research Database (Denmark)

    Björnberg, Olof; Ostergaard, Henrik; Winther, Jakob R

    2006-01-01

    Recent years have seen the development of methods for analyzing the redox conditions in specific compartments in living cells. These methods are based on genetically encoded sensors comprising variants of Green Fluorescent Protein in which vicinal cysteine residues have been introduced at solvent......-exposed positions. Several mutant forms have been identified in which formation of a disulfide bond between these cysteine residues results in changes of their fluorescence properties. The redox sensors have been characterized biochemically and found to behave differently, both spectroscopically and in terms...... of redox properties. As genetically encoded sensors they can be expressed in living cells and used for analysis of intracellular redox conditions; however, which parameters are measured depends on how the sensors interact with various cellular redox components. Results of both biochemical and cell...

  19. Energy storage device including a redox-enhanced electrolyte

    Science.gov (United States)

    Stucky, Galen; Evanko, Brian; Parker, Nicholas; Vonlanthen, David; Auston, David; Boettcher, Shannon; Chun, Sang-Eun; Ji, Xiulei; Wang, Bao; Wang, Xingfeng; Chandrabose, Raghu Subash

    2017-08-08

    An electrical double layer capacitor (EDLC) energy storage device is provided that includes at least two electrodes and a redox-enhanced electrolyte including two redox couples such that there is a different one of the redox couples for each of the electrodes. When charged, the charge is stored in Faradaic reactions with the at least two redox couples in the electrolyte and in a double-layer capacitance of a porous carbon material that comprises at least one of the electrodes, and a self-discharge of the energy storage device is mitigated by at least one of electrostatic attraction, adsorption, physisorption, and chemisorption of a redox couple onto the porous carbon material.

  20. Molecular analysis of Ku redox regulation

    Directory of Open Access Journals (Sweden)

    Shatilla Andrea

    2009-08-01

    Full Text Available Abstract Background DNA double-strand breaks (DSBs can occur in response to ionizing radiation (IR, radiomimetic agents and from endogenous DNA-damaging reactive oxygen metabolites. Unrepaired or improperly repaired DSBs are potentially the most lethal form of DNA damage and can result in chromosomal translocations and contribute to the development of cancer. The principal mechanism for the repair of DSBs in humans is non-homologous end-joining (NHEJ. Ku is a key member of the NHEJ pathway and plays an important role in the recognition step when it binds to free DNA termini. Ku then stimulates the assembly and activation of other NHEJ components. DNA binding of Ku is regulated by redox conditions and evidence from our laboratory has demonstrated that Ku undergoes structural changes when oxidized that results in a reduction in DNA binding activity. The C-terminal domain and cysteine 493 of Ku80 were investigated for their contribution to redox regulation of Ku. Results We effectively removed the C-terminal domain of Ku80 generating a truncation mutant and co-expressed this variant with wild type Ku70 in an insect cell system to create a Ku70/80ΔC heterodimer. We also generated two single amino acid variants of Cys493, replacing this amino acid with either an alanine (C493A or a serine (C493S, and over-expressed the variant proteins in SF9 insect cells in complex with wild type Ku70. Neither the truncation nor the amino acid substitutions alters protein expression or stability as determined by SDS-PAGE and Western blot analysis. We show that the C493 mutations do not alter the ability of Ku to bind duplex DNA in vitro under reduced conditions while truncation of the Ku80 C-terminus slightly reduced DNA binding affinity. Diamide oxidation of cysteines was shown to inhibit DNA binding similarly for both the wild-type and all variant proteins. Interestingly, differential DNA binding activity following re-reduction was observed for the Ku70/80

  1. Do proxies reflect patients' health concerns about urinary incontinence and gait problems?

    Science.gov (United States)

    Higashi, Takahiro; Hays, Ron D; Brown, Julie A; Kamberg, Caren J; Pham, Chau; Reuben, David B; Shekelle, Paul G; Solomon, David H; Young, Roy T; Roth, Carol P; Chang, John T; MacLean, Catherine H; Wenger, Neil S

    2005-01-01

    Background While falls and urinary incontinence are prevalent among older patients, who sometimes rely on proxies to provide their health information, the validity of proxy reports of concern about falls and urinary incontinence remains unknown. Methods Telephone interviews with 43 consecutive patients with falls or fear of falling and/or bothersome urinary incontinence and their proxies chosen by patients as most knowledgeable about their health. The questionnaire included items derived from the Medical Outcomes Study Short Form 12 (SF-12), a scale assessing concerns about urinary incontinence (UI), and a measure of fear of falling, the Falls Efficacy Scale (FES). Scores were estimated using items asking the proxy perspective (6 items from the SF-12, 10 items from a UI scale, and all 10 FES items). Proxy and patient scores were compared using intraclass correlation coefficients (ICC, one-way model). Variables associated with absolute agreement between patients and proxies were explored. Results Patients had a mean age of 81 years (range 75–93) and 67% were female while proxies had a mean age of 70 (range 42–87) and 49% were female. ICCs were 0.63 for the SF-12, 0.52 for the UI scale, and 0.29 for the FES. Proxies tended to understate patients' general health and incontinence concern, but overstate patients' concern about falling. Proxies who lived with patients and those who more often see patients more closely reflected patient FES scores compared to those who lived apart or those who saw patients less often. Internal consistency reliability of proxy responses was 0.62 for the SF-12, 0.86 for the I-QOL, and 0.93 for the FES. In addition, construct validity of the proxy FES scale was supported by greater proxy-perceived fear of falling for patients who received medical care after a fall during the past 12 months (p < .05). Conclusion Caution should be exercised when using proxies as a source of information about older patients' health perceptions. Questions

  2. Do proxies reflect patients' health concerns about urinary incontinence and gait problems?

    Directory of Open Access Journals (Sweden)

    Solomon David H

    2005-11-01

    Full Text Available Abstract Background While falls and urinary incontinence are prevalent among older patients, who sometimes rely on proxies to provide their health information, the validity of proxy reports of concern about falls and urinary incontinence remains unknown. Methods Telephone interviews with 43 consecutive patients with falls or fear of falling and/or bothersome urinary incontinence and their proxies chosen by patients as most knowledgeable about their health. The questionnaire included items derived from the Medical Outcomes Study Short Form 12 (SF-12, a scale assessing concerns about urinary incontinence (UI, and a measure of fear of falling, the Falls Efficacy Scale (FES. Scores were estimated using items asking the proxy perspective (6 items from the SF-12, 10 items from a UI scale, and all 10 FES items. Proxy and patient scores were compared using intraclass correlation coefficients (ICC, one-way model. Variables associated with absolute agreement between patients and proxies were explored. Results Patients had a mean age of 81 years (range 75–93 and 67% were female while proxies had a mean age of 70 (range 42–87 and 49% were female. ICCs were 0.63 for the SF-12, 0.52 for the UI scale, and 0.29 for the FES. Proxies tended to understate patients' general health and incontinence concern, but overstate patients' concern about falling. Proxies who lived with patients and those who more often see patients more closely reflected patient FES scores compared to those who lived apart or those who saw patients less often. Internal consistency reliability of proxy responses was 0.62 for the SF-12, 0.86 for the I-QOL, and 0.93 for the FES. In addition, construct validity of the proxy FES scale was supported by greater proxy-perceived fear of falling for patients who received medical care after a fall during the past 12 months (p Conclusion Caution should be exercised when using proxies as a source of information about older patients' health perceptions

  3. Redox biology response in germinating Phaseolus vulgaris seeds exposed to copper: Evidence for differential redox buffering in seedlings and cotyledon.

    Directory of Open Access Journals (Sweden)

    Inès Karmous

    Full Text Available In agriculture, heavy metal contamination of soil interferes with processes associated with plant growth, development and productivity. Here, we describe oxidative and redox changes, and deleterious injury within cotyledons and seedlings caused by exposure of germinating (Phaseolus vulgaris L. var. soisson nain hâtif seeds to copper (Cu. Cu induced a marked delay in seedling growth, and was associated with biochemical disturbances in terms of intracellular oxidative status, redox regulation and energy metabolism. In response to these alterations, modulation of activities of antioxidant proteins (thioredoxin and glutathione reductase, peroxiredoxin occurred, thus preventing oxidative damage. In addition, oxidative modification of proteins was detected in both cotyledons and seedlings by one- and two-dimensional electrophoresis. These modified proteins may play roles in redox buffering. The changes in activities of redox proteins underline their fundamental roles in controlling redox homeostasis. However, observed differential redox responses in cotyledon and seedling tissues showed a major capacity of the seedlings' redox systems to protect the reduced status of protein thiols, thus suggesting quantitatively greater antioxidant protection of proteins in seedlings compared to cotyledon. To our knowledge, this is the first comprehensive redox biology investigation of the effect of Cu on seed germination.

  4. The decay of Redox-stress Response Capacity is a substantive characteristic of aging: Revising the redox theory of aging.

    Science.gov (United States)

    Meng, Jiao; Lv, Zhenyu; Qiao, Xinhua; Li, Xiaopeng; Li, Yazi; Zhang, Yuying; Chen, Chang

    2017-04-01

    Aging is tightly associated with redox events. The free radical theory of aging indicates that redox imbalance may be an important factor in the aging process. Most studies about redox and aging focused on the static status of oxidative stress levels, there has been little research investigating differential responses to redox challenge during aging. In this study, we used Caenorhabditis elegans and human fibroblasts as models to compare differential responses to oxidative stress challenge in young and old individuals. In response to paraquat stress, young individuals generated more ROS and activated signaling pathways including p-ERK, p-AKT and p-AMPKα/β. After the initial response, young individuals then promoted NRF2 translocation and induced additional antioxidant enzymes and higher expression of phase II enzymes, including SOD, CAT, GPX, HO-1, GSTP-1and others, to maintain redox homeostasis. Moreover, young individuals also demonstrated a better ability to degrade damaged proteins by up-regulating the expression of chaperones and improving proteasome activity. Based on these data, we propose a new concept "Redox-stress Response Capacity (RRC)", which suggests cells or organisms are capable of generating dynamic redox responses to activate cellular signaling and maintain cellular homeostasis. The decay of RRC is the substantive characteristic of aging, which gives a new understand of the redox theory of aging. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  5. Redox biology response in germinating Phaseolus vulgaris seeds exposed to copper: Evidence for differential redox buffering in seedlings and cotyledon.

    Science.gov (United States)

    Karmous, Inès; Trevisan, Rafael; El Ferjani, Ezzeddine; Chaoui, Abdelilah; Sheehan, David

    2017-01-01

    In agriculture, heavy metal contamination of soil interferes with processes associated with plant growth, development and productivity. Here, we describe oxidative and redox changes, and deleterious injury within cotyledons and seedlings caused by exposure of germinating (Phaseolus vulgaris L. var. soisson nain hâtif) seeds to copper (Cu). Cu induced a marked delay in seedling growth, and was associated with biochemical disturbances in terms of intracellular oxidative status, redox regulation and energy metabolism. In response to these alterations, modulation of activities of antioxidant proteins (thioredoxin and glutathione reductase, peroxiredoxin) occurred, thus preventing oxidative damage. In addition, oxidative modification of proteins was detected in both cotyledons and seedlings by one- and two-dimensional electrophoresis. These modified proteins may play roles in redox buffering. The changes in activities of redox proteins underline their fundamental roles in controlling redox homeostasis. However, observed differential redox responses in cotyledon and seedling tissues showed a major capacity of the seedlings' redox systems to protect the reduced status of protein thiols, thus suggesting quantitatively greater antioxidant protection of proteins in seedlings compared to cotyledon. To our knowledge, this is the first comprehensive redox biology investigation of the effect of Cu on seed germination.

  6. Identification of redox-sensitive cysteines in the arabidopsis proteome using OxiTRAQ, a quantitative redox proteomics method

    KAUST Repository

    Liu, Pei

    2014-01-28

    Cellular redox status plays a key role in mediating various physiological and developmental processes often through modulating activities of redox-sensitive proteins. Various stresses trigger over-production of reactive oxygen/nitrogen species which lead to oxidative modifications of redox-sensitive proteins. Identification and characterization of redox-sensitive proteins are important steps toward understanding molecular mechanisms of stress responses. Here, we report a high-throughput quantitative proteomic approach termed OxiTRAQ for identifying proteins whose thiols undergo reversible oxidative modifications in Arabidopsis cells subjected to oxidative stress. In this approach, a biotinylated thiol-reactive reagent is used for differential labeling of reduced and oxidized thiols. The biotin-tagged peptides are affinity purified, labeled with iTRAQ reagents, and analyzed using a paralleled HCD-CID fragmentation mode in an LTQ-Orbitrap. With this approach, we identified 195 cysteine-containing peptides from 179 proteins whose thiols underwent oxidative modifications in Arabidopsis cells following the treatment with hydrogen peroxide. A majority of those redox-sensitive proteins, including several transcription factors, were not identified by previous redox proteomics studies. This approach allows identification of the specific redox-regulated cysteine residues, and offers an effective tool for elucidation of redox proteomes. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Effects of stimulus-driven synchronization on sensory perception

    Directory of Open Access Journals (Sweden)

    Holden Jameson K

    2007-12-01

    Full Text Available Abstract Background A subject's ability to differentiate the loci of two points on the skin depends on the stimulus-evoked pericolumnar lateral inhibitory interactions which increase the spatial contrast between regions of SI cortex that are activated by stimulus-evoked afferent drive. Nevertheless, there is very little known about the impact that neuronal interactions – such as those evoked by mechanical skin stimuli that project to and coordinate synchronized activity in adjacent and/or near-adjacent cortical columns – could have on sensory information processing. Methods The temporal order judgment (TOJ and temporal discriminative threshold (TDT of 20 healthy adult subjects were assessed both in the absence and presence of concurrent conditions of tactile stimulation. These measures were obtained across a number of paired sites – two unilateral and one bilateral – and several conditions of adapting stimuli were delivered both prior to and concurrently with the TOJ and TDT tasks. The pairs of conditioning stimuli were synchronized and periodic, synchronized and non-periodic, or asynchronous and non-periodic. Results In the absence of any additional stimuli, TOJ and TDT results obtained from the study were comparable across a number of pairs of stimulus sites – unilateral as well as bilateral. In the presence of a 25 Hz conditioning sinusoidal stimulus which was delivered both before, concurrently and after the TOJ task, there was a significant change in the TOJ measured when the two stimuli were located unilaterally on digits 2 and 3. However, in the presence of the same 25 Hz conditioning stimulus, the TOJ obtained when the two stimuli were delivered bilaterally was not impacted. TDT measures were not impacted to the same degree by the concurrent stimuli that were delivered to the unilateral or bilateral stimulus sites. This led to the speculation that the impact that the conditioning stimuli – which were sinusoidal, periodic and

  8. Subcellular Redox Targeting: Bridging in Vitro and in Vivo Chemical Biology.

    Science.gov (United States)

    Long, Marcus J C; Poganik, Jesse R; Ghosh, Souradyuti; Aye, Yimon

    2017-03-17

    Networks of redox sensor proteins within discrete microdomains regulate the flow of redox signaling. Yet, the inherent reactivity of redox signals complicates the study of specific redox events and pathways by traditional methods. Herein, we review designer chemistries capable of measuring flux and/or mimicking subcellular redox signaling at the cellular and organismal level. Such efforts have begun to decipher the logic underlying organelle-, site-, and target-specific redox signaling in vitro and in vivo. These data highlight chemical biology as a perfect gateway to interrogate how nature choreographs subcellular redox chemistry to drive precision redox biology.

  9. Exercise and Glycemic Control: Focus on Redox Homeostasis and Redox-Sensitive Protein Signaling

    Science.gov (United States)

    Parker, Lewan; Shaw, Christopher S.; Stepto, Nigel K.; Levinger, Itamar

    2017-01-01

    Physical inactivity, excess energy consumption, and obesity are associated with elevated systemic oxidative stress and the sustained activation of redox-sensitive stress-activated protein kinase (SAPK) and mitogen-activated protein kinase signaling pathways. Sustained SAPK activation leads to aberrant insulin signaling, impaired glycemic control, and the development and progression of cardiometabolic disease. Paradoxically, acute exercise transiently increases oxidative stress and SAPK signaling, yet postexercise glycemic control and skeletal muscle function are enhanced. Furthermore, regular exercise leads to the upregulation of antioxidant defense, which likely assists in the mitigation of chronic oxidative stress-associated disease. In this review, we explore the complex spatiotemporal interplay between exercise, oxidative stress, and glycemic control, and highlight exercise-induced reactive oxygen species and redox-sensitive protein signaling as important regulators of glucose homeostasis. PMID:28529499

  10. Hybrid anodes for redox flow batteries

    Science.gov (United States)

    Wang, Wei; Xiao, Jie; Wei, Xiaoliang; Liu, Jun; Sprenkle, Vincent L.

    2015-12-15

    RFBs having solid hybrid electrodes can address at least the problems of active material consumption, electrode passivation, and metal electrode dendrite growth that can be characteristic of traditional batteries, especially those operating at high current densities. The RFBs each have a first half cell containing a first redox couple dissolved in a solution or contained in a suspension. The solution or suspension can flow from a reservoir to the first half cell. A second half cell contains the solid hybrid electrode, which has a first electrode connected to a second electrode, thereby resulting in an equipotential between the first and second electrodes. The first and second half cells are separated by a separator or membrane.

  11. High energy density redox flow device

    Energy Technology Data Exchange (ETDEWEB)

    Carter, W. Craig; Chiang, Yet-Ming; Duduta, Mihai; Limthongkul, Pimpa

    2017-04-04

    Redox flow devices are described including a positive electrode current collector, a negative electrode current collector, and an ion-permeable membrane separating said positive and negative current collectors, positioned and arranged to define a positive electroactive zone and a negative electroactive zone; wherein at least one of said positive and negative electroactive zone comprises a flowable semi-solid composition comprising ion storage compound particles capable of taking up or releasing said ions during operation of the cell, and wherein the ion storage compound particles have a polydisperse size distribution in which the finest particles present in at least 5 vol % of the total volume, is at least a factor of 5 smaller than the largest particles present in at least 5 vol % of the total volume.

  12. Iron-sulfide redox flow batteries

    Science.gov (United States)

    Xia, Guan-Guang; Yang, Zhenguo; Li, Liyu; Kim, Soowhan; Liu, Jun; Graff, Gordon L

    2013-12-17

    Iron-sulfide redox flow battery (RFB) systems can be advantageous for energy storage, particularly when the electrolytes have pH values greater than 6. Such systems can exhibit excellent energy conversion efficiency and stability and can utilize low-cost materials that are relatively safer and more environmentally friendly. One example of an iron-sulfide RFB is characterized by a positive electrolyte that comprises Fe(III) and/or Fe(II) in a positive electrolyte supporting solution, a negative electrolyte that comprises S.sup.2- and/or S in a negative electrolyte supporting solution, and a membrane, or a separator, that separates the positive electrolyte and electrode from the negative electrolyte and electrode.

  13. Voice attractiveness: influence of stimulus duration and type.

    Science.gov (United States)

    Ferdenzi, C; Patel, S; Mehu-Blantar, I; Khidasheli, M; Sander, D; Delplanque, S

    2013-06-01

    Voice attractiveness is a relatively new area of research. Some aspects of the methodology used in this domain deserve particular attention. Especially, the duration of voice samples is often neglected as a factor and happens to be manipulated without the perceptual consequences of these manipulations being known. Moreover, the type of voice stimulus varies from a single vowel to complex sentences. The aim of this experiment was to investigate the extent to which stimulus duration (nonmanipulated vs. normalized) and type (vowel vs. word) influence perceived voice attractiveness. Twenty-seven male and female raters made attractiveness judgments of 30 male and female voice samples. Voice samples included a single vowel /a/, a three-vowel series /i a o/, and the French word "bonjour" (i.e., "hello"). These samples were presented in three conditions: nonmanipulated, shortened, and lengthened duration. Duration manipulation was performed using the pitch synchronous overlap and add (PSOLA) algorithm implemented in Praat. Results for the effect of stimulus type showed that word length samples were more attractive to the opposite sex than vowels. Results for the effect of duration showed that the nonmanipulated sound sample duration was not predictive of perceived attractiveness. Duration manipulation, on the other hand, altered perceived attractiveness for the lengthening condition. In particular, there was a linear decrease in attractiveness as a function of modification percentage (especially for the word, as compared with the vowels). Recommendations for voice sample normalization with the PSOLA algorithm are thus to prefer shortening over lengthening and, if not possible, to limit the extent of duration manipulation-for example, by normalizing to the mean sample duration.

  14. Lung extracellular matrix and redox regulation.

    Science.gov (United States)

    Watson, Walter H; Ritzenthaler, Jeffrey D; Roman, Jesse

    2016-08-01

    Pulmonary fibrosis affects millions worldwide and, even though there has been a significant investment in understanding the processes involved in wound healing and maladaptive repair, a complete understanding of the mechanisms responsible for lung fibrogenesis eludes us, and interventions capable of reversing or halting disease progression are not available. Pulmonary fibrosis is characterized by the excessive expression and uncontrolled deposition of extracellular matrix (ECM) proteins resulting in erosion of the tissue structure. Initially considered an 'end-stage' process elicited after injury, these events are now considered pathogenic and are believed to contribute to the course of the disease. By interacting with integrins capable of signal transduction and by influencing tissue mechanics, ECM proteins modulate processes ranging from cell adhesion and migration to differentiation and growth factor expression. In doing so, ECM proteins help orchestrate complex developmental processes and maintain tissue homeostasis. However, poorly controlled deposition of ECM proteins promotes inflammation, fibroproliferation, and aberrant differentiation of cells, and has been implicated in the pathogenesis of pulmonary fibrosis, atherosclerosis and cancer. Considering their vital functions, ECM proteins are the target of investigation, and oxidation-reduction (redox) reactions have emerged as important regulators of the ECM. Oxidative stress invariably accompanies lung disease and promotes ECM expression directly or through the overproduction of pro-fibrotic growth factors, while affecting integrin binding and activation. In vitro and in vivo investigations point to redox reactions as targets for intervention in pulmonary fibrosis and related disorders, but studies in humans have been disappointing probably due to the narrow impact of the interventions tested, and our poor understanding of the factors that regulate these complex reactions. This review is not meant to

  15. Chemistry and Redox Biology of Mycothiol.

    Science.gov (United States)

    Reyes, Aníbal M; Pedre, Brandán; De Armas, María Inés; Tossounian, Maria-Armineh; Radi, Rafael; Messens, Joris; Trujillo, Madia

    2018-02-20

    Mycothiol (MSH, AcCys-GlcN-Ins) is the main low-molecular weight (LMW) thiol of most Actinomycetes, including the human pathogen Mycobacterium tuberculosis that affects millions of people worldwide. Strains with decreased MSH content show increased susceptibilities to hydroperoxides and electrophilic compounds. In M. tuberculosis, MSH modulates the response to several antituberculosis drugs. Enzymatic routes involving MSH could provide clues for specific drug design. Recent Advances: Physicochemical data argue against a rapid, nonenzymatic reaction of MSH with oxidants, disulfides, or electrophiles. Moreover, exposure of the bacteria to high concentrations of two-electron oxidants resulted in protein mycothiolation. The recently described glutaredoxin-like protein mycoredoxin-1 (Mrx-1) provides a route for catalytic reduction of mycothiolated proteins, protecting critical cysteines from irreversible oxidation. The description of MSH/Mrx-1-dependent activities of peroxidases helped to explain the higher susceptibility to oxidants observed in Actinomycetes lacking MSH. Moreover, the first mycothiol-S-transferase, member of the DinB superfamily of proteins, was described. In Corynebacterium, both the MSH/Mrx-1 and the thioredoxin pathways reduce methionine sulfoxide reductase A. A novel tool for in vivo imaging of the MSH/mycothiol disulfide (MSSM) status allows following changes in the mycothiol redox state during macrophage infection and its relationship with antibiotic sensitivity. Redundancy of MSH with other LMW thiols is starting to be unraveled and could help to rationalize the differences in the reported importance of MSH synthesis observed in vitro versus in animal infection models. Future work should be directed to establish the structural bases of the specificity of MSH-dependent enzymes, thus facilitating drug developments. Antioxid. Redox Signal. 28, 487-504.

  16. The poverty of the stimulus: Quine and Wittgenstein

    Directory of Open Access Journals (Sweden)

    O’Sullivan Michael

    2014-01-01

    Full Text Available Quine and Wittgenstein were dominant figures in philosophy in the middle of the twentieth century. Many readers, like Quine himself, have felt that there are deep similarities between the two thinkers, though those similarities are difficult to articulate. I argue that they share the project of understanding the meaning of utterances by reference to the environment of the speaker, though they understand that environment in radically different ways. In particular, Quine has a much thinner conception of the environment than does Wittgenstein. For Quine, the stimulus is impoverished in a way that it is not for Wittgenstein. I also argue that they share a certain deflationary approach to ontology.

  17. Validity of electrical stimulus magnitude matching in chronic pain

    DEFF Research Database (Denmark)

    Persson, Ann L; Westermark, Sofia; Merrick, Daniel

    2009-01-01

    OBJECTIVE: To examine the validity of the PainMatcher in chronic pain. DESIGN: Comparison of parallel pain estimates from visual analogue scales with electrical stimulus magnitude matching. PATIENTS: Thirty-one patients with chronic musculoskeletal pain. METHODS: Twice a day ongoing pain was rated...... range of the instrument, the PainMatcher readings utilized only a small part of the instrument range and, importantly, had little or no relation to the visual analogue scale estimates. The validity of the PainMatcher procedure is doubtful....

  18. Brief-stimulus presentations on multiform tandem schedules

    OpenAIRE

    Reed, Phil

    1994-01-01

    Three experiments examined the influence of a brief stimulus (a light) on the behavior of food-deprived rats whose lever pressing on tandem schedules comprising components of different schedule types resulted in food presentation. In Experiment 1, either a tandem variable-ratio variable-interval or a tandem variable-interval variable-ratio schedule was used. The variable-interval requirement in the tandem variable-ratio variable-interval schedule was yoked to the time taken to complete the va...

  19. Intention-based and stimulus-based mechanisms in action selection.

    Science.gov (United States)

    Waszak, Florian; Wascher, Edmund; Keller, Peter; Koch, Iring; Aschersleben, Gisa; Rosenbaum, David A; Prinz, Wolfgang

    2005-04-01

    Human actions can be classified as being either more stimulus-based or more intention-based. According to the ideomotor framework of action control, intention-based actions primarily refer to anticipated action effects (in other words response-stimulus [R-S] bindings), whereas stimulus-based actions are commonly assumed to be more strongly determined by stimulus-response [S-R] bindings. We explored differences in the functional signatures of both modes of action control in a temporal bisection task. Participants either performed a choice response by pressing one out of two keys in response to a preceding stimulus (stimulus-based action), or pressed one out of two keys to produce the next stimulus (intention-based action). In line with the ideomotor framework, we found intention-based actions to be shifted in time towards their anticipated effects (the next stimulus), whereas stimulus-based actions were shifted towards their preceding stimulus. Event-related potentials (ERPs) in the EEG revealed marked differences in action preparation for the two tasks. The data as a whole provide converging evidence for functional differences in the selection of motor actions as a function of their triggering conditions, and support the notion of two different modes of action selection, one being exogenous or mainly stimulus-driven, the other being endogenous or mainly intention-driven.

  20. Fractal gait patterns are retained after entrainment to a fractal stimulus.

    Science.gov (United States)

    Rhea, Christopher K; Kiefer, Adam W; Wittstein, Matthew W; Leonard, Kelsey B; MacPherson, Ryan P; Wright, W Geoffrey; Haran, F Jay

    2014-01-01

    Previous work has shown that fractal patterns in gait can be altered by entraining to a fractal stimulus. However, little is understood about how long those patterns are retained or which factors may influence stronger entrainment or retention. In experiment one, participants walked on a treadmill for 45 continuous minutes, which was separated into three phases. The first 15 minutes (pre-synchronization phase) consisted of walking without a fractal stimulus, the second 15 minutes consisted of walking while entraining to a fractal visual stimulus (synchronization phase), and the last 15 minutes (post-synchronization phase) consisted of walking without the stimulus to determine if the patterns adopted from the stimulus were retained. Fractal gait patterns were strengthened during the synchronization phase and were retained in the post-synchronization phase. In experiment two, similar methods were used to compare a continuous fractal stimulus to a discrete fractal stimulus to determine which stimulus type led to more persistent fractal gait patterns in the synchronization and post-synchronization (i.e., retention) phases. Both stimulus types led to equally persistent patterns in the synchronization phase, but only the discrete fractal stimulus led to retention of the patterns. The results add to the growing body of literature showing that fractal gait patterns can be manipulated in a predictable manner. Further, our results add to the literature by showing that the newly adopted gait patterns are retained for up to 15 minutes after entrainment and showed that a discrete visual stimulus is a better method to influence retention.

  1. 75 FR 9073 - Amendments to Rules Requiring Internet Availability of Proxy Materials

    Science.gov (United States)

    2010-02-26

    ... an Internet Web site; it is not intended to serve as a stand-alone basis for making a voting decision... Exchange Commission 17 CFR Parts 230 and 240 Amendments to Rules Requiring Internet Availability of Proxy... Rules Requiring Internet Availability of Proxy Materials AGENCY: Securities and Exchange Commission...

  2. Improving age-depth models using sedimentary proxies for accumulation rates in fluvio-lacustrine deposits

    NARCIS (Netherlands)

    Minderhoud, P.S.J.; Cohen, K.M.|info:eu-repo/dai/nl/185633374; Toonen, W.H.J.|info:eu-repo/dai/nl/317725505; Erkens, G.|info:eu-repo/dai/nl/323349382; Hoek, W.Z.|info:eu-repo/dai/nl/163819394

    2017-01-01

    Lacustrine fills, including those of oxbow lakes in river floodplains, often hold valuable sedimentary and biological proxy records of palaeo-environmental change. Precise dating of accumulated sediments at levels throughout these records is crucial for interpretation and correlation of (proxy) data

  3. 47 CFR 51.513 - Proxies for forward-looking economic cost.

    Science.gov (United States)

    2010-10-01

    ... SERVICES (CONTINUED) INTERCONNECTION Pricing of Elements § 51.513 Proxies for forward-looking economic cost... a cost study that complies with the forward-looking economic cost based pricing methodology... rates that apply in separate geographic areas in a state. (c) Proxies for specific elements—(1) Local...

  4. Diagnostic, Explanatory, and Detection Models of Munchausen by Proxy: Extrapolations from Malingering and Deception

    Science.gov (United States)

    Rogers, Richard

    2004-01-01

    Objective: The overriding objective is a critical examination of Munchausen syndrome by proxy (MSBP) and its closely-related alternative, factitious disorder by proxy (FDBP). Beyond issues of diagnostic validity, assessment methods and potential detection strategies are explored. Methods: A painstaking analysis was conducted of the MSBP and FDBP…

  5. Anxiety and worry when coping with cancer treatment: agreement between patient and proxy responses.

    Science.gov (United States)

    Hermont, Ana Paula; Scarpelli, Ana Carolina; Paiva, Saul M; Auad, Sheyla M; Pordeus, Isabela A

    2015-06-01

    Assess agreement between proxy respondents (caregivers) and children/adolescents related to the impact of cancer on children's/adolescents' health-related quality of life, with respect to anxiety and worry issues. A cross-sectional study was conducted among 83 Brazilian children/adolescents, of both genders, diagnosed with cancer, aged 5-18 years and their proxy respondents. Anxiety and worry were assessed through items of the instrument Pediatric Quality of Life Inventory™ Cancer Module Scale. Participants were recruited from the pediatric hematology/oncology centers at two public hospitals. All individuals were receiving medical care. Descriptive statistics were performed as well as a weighted kappa coefficient, Spearman's correlation coefficient, Wilcoxon signed-rank test and Bland-Altman plots. The magnitude of the difference between the mean scores obtained from children/adolescents and that of their proxy respondents was evaluated through effect size. The proxy respondents underestimated the feelings of worry among children (8-12 years) (p anxiety (p children/adolescents to report increasing feelings of worry as they got older. In the 'treatment anxiety' subscale, there was a tendency for proxy respondents to present higher mean scores, revealing that proxy respondents believed the children's/adolescents' treatment anxiety decreased as they aged. Discrepancies between the reports of children/adolescents and their proxy respondents were observed. Children's/adolescents' reports should not be ignored nor replaced by proxy reports; both reports should be analyzed together.

  6. Evidence for local and global redox conditions at an Early Ordovician (Tremadocian) mass extinction

    Science.gov (United States)

    Edwards, Cole T.; Fike, David A.; Saltzman, Matthew R.; Lu, Wanyi; Lu, Zunli

    2018-01-01

    Profound changes in environmental conditions, particularly atmospheric oxygen levels, are thought to be important drivers of several major biotic events (e.g. mass extinctions and diversifications). The early Paleozoic represents a key interval in the oxygenation of the ocean-atmosphere system and evolution of the biosphere. Global proxies (e.g. carbon (δ13C) and sulfur (δ34S) isotopes) are used to diagnose potential changes in oxygenation and infer causes of environmental change and biotic turnover. The Cambrian-Ordovician contains several trilobite extinctions (some are apparently local, but others are globally correlative) that are attributed to anoxia based on coeval positive δ13C and δ34S excursions. These extinction and excursion events have yet to be coupled with more recently developed proxies thought to be more reflective of local redox conditions in the water column (e.g. I/Ca) to confirm whether these extinctions were associated with oxygen crises over a regional or global scale. Here we examine an Early Ordovician (Tremadocian Stage) extinction event previously interpreted to reflect a continuation of recurrent early Paleozoic anoxic events that expanded into nearshore environments. δ13C, δ34S, and I/Ca trends were measured from three sections in the Great Basin region to test whether I/Ca trends support the notion that anoxia was locally present in the water column along the Laurentian margin. Evidence for anoxia is based on coincident, but not always synchronous, positive δ13C and δ34S excursions (mainly from carbonate-associated sulfate and less so from pyrite data), a 30% extinction of standing generic diversity, and near-zero I/Ca values. Although evidence for local water column anoxia from the I/Ca proxy broadly agrees with intervals of global anoxia inferred from δ13C and δ34S trends, a more complex picture is evident where spatially and temporally variable local trends are superimposed on time-averaged global trends. Stratigraphic

  7. Patient-rated versus proxy-rated cognitive and functional measures in older adults

    Directory of Open Access Journals (Sweden)

    Howland M

    2017-03-01

    Full Text Available Molly Howland,1 Kevin C Allan,1 Caitlin E Carlton,1 Curtis Tatsuoka,2–4 Kathleen A Smyth,3 Martha Sajatovic1,2,4,5 1Case Western Reserve University School of Medicine, 2Neurological and Behavioral Outcomes Center, University Hospitals Case Medical Center, 3Department of Epidemiology and Biostatistics, 4Department of Neurology, 5Department of Psychiatry, Case Western Reserve University School of Medicine, Cleveland, OH, USA Objectives: Patients with cognitive impairment may have difficulty reporting their functional and cognitive abilities, which are important clinical outcomes. Health care proxies may be able to corroborate patient self-reports. Several studies reported discrepancy between patient and proxy ratings, though the literature is sparse on changes over time of these ratings. Our goals in this 12-month study were to compare patient and proxy reports on functioning, cognition, and everyday executive function, and to further elucidate correlates of patient–proxy discrepancy. Methods: This was a prospective cohort study of individuals older than 70 years who ranged from having no cognitive impairment to having moderate dementia who had a proxy available to complete instruments at baseline (N=76. Measurements included Alzheimer’s Disease Cooperative Study–Activities of Daily Living Inventory (ADCS-ADLI, Neuro-QOL Executive Function, PROMIS Applied Cognition (PROMIS-Cog, Mini-Mental State Examination (MMSE, and Geriatric Depression Scale. Results: Patient- and proxy-rated ADCS-ADLI were correlated at baseline and at 1-year follow-up. Patient and proxy ratings were discrepant on Neuro-QOL Executive Function and PROMIS-Cog. Greater patient–proxy discrepancy on PROMIS-Cog was associated with younger age and less depression, and greater patient–proxy discrepancy on Neuro-QOL Executive Function was associated with less depression and worse cognitive impairment. Patient–proxy discrepancy increased over time for everyday executive

  8. Pseudo-proxy evaluation of climate field reconstruction methods of North Atlantic climate based on an annually resolved marine proxy network

    Science.gov (United States)

    Pyrina, Maria; Wagner, Sebastian; Zorita, Eduardo

    2017-10-01

    Two statistical methods are tested to reconstruct the interannual variations in past sea surface temperatures (SSTs) of the North Atlantic (NA) Ocean over the past millennium based on annually resolved and absolutely dated marine proxy records of the bivalve mollusk Arctica islandica. The methods are tested in a pseudo-proxy experiment (PPE) setup using state-of-the-art climate models (CMIP5 Earth system models) and reanalysis data from the COBE2 SST data set. The methods were applied in the virtual reality provided by global climate simulations and reanalysis data to reconstruct the past NA SSTs using pseudo-proxy records that mimic the statistical characteristics and network of Arctica islandica. The multivariate linear regression methods evaluated here are principal component regression and canonical correlation analysis. Differences in the skill of the climate field reconstruction (CFR) are assessed according to different calibration periods and different proxy locations within the NA basin. The choice of the climate model used as a surrogate reality in the PPE has a more profound effect on the CFR skill than the calibration period and the statistical reconstruction method. The differences between the two methods are clearer for the MPI-ESM model due to its higher spatial resolution in the NA basin. The pseudo-proxy results of the CCSM4 model are closer to the pseudo-proxy results based on the reanalysis data set COBE2. Conducting PPEs using noise-contaminated pseudo-proxies instead of noise-free pseudo-proxies is important for the evaluation of the methods, as more spatial differences in the reconstruction skill are revealed. Both methods are appropriate for the reconstruction of the temporal evolution of the NA SSTs, even though they lead to a great loss of variance away from the proxy sites. Under reasonable assumptions about the characteristics of the non-climate noise in the proxy records, our results show that the marine network of Arctica islandica can

  9. Pseudo-proxy evaluation of climate field reconstruction methods of North Atlantic climate based on an annually resolved marine proxy network

    Directory of Open Access Journals (Sweden)

    M. Pyrina

    2017-10-01

    Full Text Available Two statistical methods are tested to reconstruct the interannual variations in past sea surface temperatures (SSTs of the North Atlantic (NA Ocean over the past millennium based on annually resolved and absolutely dated marine proxy records of the bivalve mollusk Arctica islandica. The methods are tested in a pseudo-proxy experiment (PPE setup using state-of-the-art climate models (CMIP5 Earth system models and reanalysis data from the COBE2 SST data set. The methods were applied in the virtual reality provided by global climate simulations and reanalysis data to reconstruct the past NA SSTs using pseudo-proxy records that mimic the statistical characteristics and network of Arctica islandica. The multivariate linear regression methods evaluated here are principal component regression and canonical correlation analysis. Differences in the skill of the climate field reconstruction (CFR are assessed according to different calibration periods and different proxy locations within the NA basin. The choice of the climate model used as a surrogate reality in the PPE has a more profound effect on the CFR skill than the calibration period and the statistical reconstruction method. The differences between the two methods are clearer for the MPI-ESM model due to its higher spatial resolution in the NA basin. The pseudo-proxy results of the CCSM4 model are closer to the pseudo-proxy results based on the reanalysis data set COBE2. Conducting PPEs using noise-contaminated pseudo-proxies instead of noise-free pseudo-proxies is important for the evaluation of the methods, as more spatial differences in the reconstruction skill are revealed. Both methods are appropriate for the reconstruction of the temporal evolution of the NA SSTs, even though they lead to a great loss of variance away from the proxy sites. Under reasonable assumptions about the characteristics of the non-climate noise in the proxy records, our results show that the marine network of Arctica

  10. Health-related quality of life after stroke: reliability of proxy responses

    DEFF Research Database (Denmark)

    Muus, Ingrid; Petzold, Max; Ringsberg, Karin C

    2009-01-01

    A Danish version of the Stroke-Specific Quality of Life Scale (SSQOL-DK) has been developed for self-reporting; it contains 12 physical and psychosocial domains. The purpose of this study was (a) to assess the reliability of the proxy version of the SSQOL-DK and (b) to evaluate the influence...... of frequency of proxy contact on agreement. In all, 143 patients completed the SSQOL-DK 1 to 5 years post-stroke. A patient chosen proxy completed a proxy version of the same questionnaire. The proxy version showed satisfactory internal consistency (Cronbach's alpha = .85-.95). Agreement was generally high...... of the SSQOL-DK appears to be reliable for use with stroke patients up to a few years following a stroke....

  11. Bicarbonate Induced Redox Proteome Changes in Arabidopsis Suspension Cells

    Science.gov (United States)

    Yin, Zepeng; Balmant, Kelly; Geng, Sisi; Zhu, Ning; Zhang, Tong; Dufresne, Craig; Dai, Shaojun; Chen, Sixue

    2017-01-01

    Climate change as a result of increasing atmospheric CO2 affects plant growth and productivity. CO2 is not only a carbon donor for photosynthesis but also an environmental signal that can perturb cellular redox homeostasis and lead to modifications of redox-sensitive proteins. Although redox regulation of protein functions has emerged as an important mechanism in several biological processes, protein redox modifications and how they function in plant CO2 response remain unclear. Here a new iodoTMTRAQ proteomics technology was employed to analyze changes in protein redox modifications in Arabidopsis thaliana suspension cells in response to bicarbonate (mimic of elevated CO2) in a time-course study. A total of 47 potential redox-regulated proteins were identified with functions in carbohydrate and energy metabolism, transport, ROS scavenging, cell structure modulation and protein turnover. This inventory of previously unknown redox responsive proteins in Arabidopsis bicarbonate responses lays a foundation for future research toward understanding the molecular mechanisms underlying plant CO2 responses. PMID:28184230

  12. Redox-regulated transcription in plants: Emerging concepts

    Directory of Open Access Journals (Sweden)

    Jehad Shaikhali

    2017-09-01

    Full Text Available In plants, different stimuli, both internal and external, activate production of reactive oxygen species (ROS. Photosynthesis is considered as high rate redox-metabolic process with rapid transients including light/photon capture, electron fluxes, and redox potentials that can generate ROS; thus, regulatory systems are required to minimize ROS production. Despite their potential for causing harmful oxidations, it is now accepted that redox homeostasis mechanisms that maintain the intracellular reducing environment make it possible to use ROS as powerful signaling molecules within and between cells. Redox and ROS information from the chloroplasts is a fine-tuning mechanism both inside the chloroplast and as retrograde signal to the cytosol and nucleus to control processes such as gene expression/transcription and translation. Wide repertoires of downstream target genes expression (activation/repression is regulated by transcription factors. In many cases, transcription factors function through various mechanisms that affect their subcellular localization and or activity. Some post-translational modifications (PTMs known to regulate the functional state of transcription factors are phosphorylation, acetylation, and SUMOylation, ubiquitylation and disulfide formation. Recently, oxPTMs, targeted in redox proteomics, can provide the bases to study redox regulation of low abundant nuclear proteins. This review summarizes the recent advances on how cellular redox status can regulate transcription factor activity, the implications of this regulation for plant growth and development, and by which plants respond to environmental/abiotic stresses.

  13. Colloidal Supercapattery: Redox Ions in Electrode and Electrolyte.

    Science.gov (United States)

    Chen, Kunfeng; Xue, Dongfeng

    2017-09-11

    Redox chemistry is the cornerstone of various electrochemical energy conversion and storage systems, associated with ion diffusion process. To actualize both high energy and power density in energy storage devices, both multiple electron transfer reaction and fast ion diffusion occurred in one electrode material are prerequisite. The existence forms of redox ions can lead to different electrochemical thermodynamic and kinetic properties. Here, we introduce novel colloid system, which includes multiple varying ion forms, multi-interaction and abundant redox active sites. Unlike redox cations in solution and crystal materials, colloid system has specific reactivity-structure relationship. In the colloidal ionic electrode, the occurrence of multiple-electron redox reactions and fast ion diffusion leaded to ultrahigh specific capacitance and fast charge rate. The colloidal ionic supercapattery coupled with redox electrolyte provides a new potential technique for the comprehensive use of redox ions including cations and anions in electrode and electrolyte and a guiding design for the development of next-generation high performance energy storage devices. © 2017 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Chronoamperometry-Based Redox Cycling for Application to Immunoassays.

    Science.gov (United States)

    Lee, Ga-Yeon; Park, Jun-Hee; Chang, Young Wook; Cho, Sungbo; Kang, Min-Jung; Pyun, Jae-Chul

    2018-01-26

    In this work, the chronoamperometry-based redox cycling of 3,3',5,5'-tetramethylbenzidine (TMB) was performed by using interdigitated electrode (IDE). The signal was obtained from two sequential chronoamperometric profiles: (1) with the generator at the oxidative potential of TMB and the collector at the reductive potential of TMB, and (2) with the generator at the reductive potential of TMB and the collector at the oxidative potential of TMB. The chronoamperometry-based redox cycling (dual mode) showed a sensitivity of 1.49 μA/OD, and the redox cycling efficiency was estimated to be 94% (n = 10). The sensitivities of conventional redox cycling with the same interdigitated electrode and chronoamperometry using a single working electrode (single mode) were estimated to be 0.67 μA/OD and 0.18 μA/OD, respectively. These results showed that the chronoamperometry-based redox cycling (dual mode) could be more effectively used to quantify the oxidized TMB than other amperometric methods. The chronoamperometry-based redox cycling (dual mode) was applied to immunoassays using a commercial ELISA kit for medical diagnosis of the human hepatitis B virus surface antigen (hHBsAg). Finally, the chronoamperometry-based redox cycling (dual mode) provided more than a 10-fold higher sensitivity than conventional chronoamperometry using a single working electrode (single mode) when applied to a commercial ELISA kit for medical diagnosis of hHBsAg.

  15. Flavor Identification and Intensity: Effects of Stimulus Context

    Science.gov (United States)

    Hallowell, Emily S.; Parikh, Roshan; Veldhuizen, Maria G.

    2016-01-01

    Two experiments presented oral mixtures containing different proportions of the gustatory flavorant sucrose and an olfactory flavorant, either citral (Experiment 1) or lemon (Experiment 2). In 4 different sessions of each experiment, subjects identified each mixture as “mostly sugar” or “mostly citrus/lemon” or rated the perceived intensities of the sweet and citrus components. Different sessions also presented the mixtures in different contexts, with mixtures containing relatively high concentrations of sucrose or citral/lemon presented more often (skew sucrose or skew citral/lemon). As expected, in both experiments, varying stimulus context affected both identification and perceived intensity: Skewing to sucrose versus citral/lemon decreased the probability of identifying the stimuli as “mostly sugar” and reduced the ratings of sweet intensity relative to citrus intensity. Across both contextual conditions of both experiments, flavor identification associated closely with the ratio of the perceived sweet and citrus intensities. The results accord with a model, extrapolated from signal-detection theory, in which sensory events are represented as multisensory–multidimensional distributions in perceptual space. Changing stimulus context can shift the locations of the distributions relative to response criteria, Decision rules guide judgments based on both sensory events and criteria, these rules not necessarily being identical in tasks of identification and intensity rating. PMID:26830499

  16. The Grand Canyon midair collision. A stimulus for change.

    Science.gov (United States)

    Murphy, G K

    1990-06-01

    Commercial aviation in the United States developed rapidly from a nucleus of pilots who returned from World War I, barnstormed and flew primitive airmail routes, and were hired by the new commerical airlines of the 1930s. The death of U.S. Senator Bronson Cutting in a 1935 crash was an important stimulus to improved governmental regulation of civil aviation. The air traffic control system, primitive until and throughout World War II, was soon proven to be inadequate for postwar demands. The midair collision of two large airliners over the Grand Canyon in June 1956 that killed the 128 persons on board was itself a strong stimulus for serious efforts, particularly in improving air traffic control systems. This and many other difficult problems in aviation safety have been addressed in the subsequent 33 years, some with success, although it has not always been immediate, and with major accidents still occurring. Commercial air travel is safe and widely accepted, however, and there is promise for additional important advances here.

  17. Fetal brain activity and hemodynamic response to a vibroacoustic stimulus.

    Science.gov (United States)

    Fulford, Jonathan; Vadeyar, Shantala H; Dodampahala, Sanani H; Ong, Stephen; Moore, Rachel J; Baker, Philip N; James, David K; Gowland, Penny

    2004-06-01

    Previous studies have demonstrated the practicality of using functional magnetic resonance imaging (fMRI) techniques to assess fetal brain activity. The purpose of this study was to compare the fetal hemodynamic response to that of the adult. Seventeen pregnant subjects, all of whom were at more than 36 weeks gestation were scanned while the fetus was exposed to a vibroacoustic stimulus. Thirteen adult subjects were scanned with an equivalent acoustic stimulus. Of the fetal subjects, two could not be analyzed due to technical problems, eight did not show significant activation, and seven showed significant activation. In all cases, activation was localized within the temporal region. Measures of fetal hemodynamic responses revealed an average time to peak (ttp) of 7.36 +/- 0.94 sec and an average percentage change of 2.67 +/- 0.93%. In contrast, activation was detected in 5 of 13 adults with an average ttp of 6.54 +/- 0.54 sec and an average percentage change of 1.02 +/- 0.40%. The measurement of changes in the fetal hemodynamic response may be important in assessing compromised pregnancies. Copyright 2004 Wiley-Liss, Inc.

  18. Adduction of untested derived stimulus relations depends on environmental complexity.

    Science.gov (United States)

    Rippy, Sterling M; Doughty, Adam H

    2017-10-01

    The present research assessed adduction involving derived stimulus relations as a function of environmental complexity. In Group CA, four college students were trained with arbitrary-matching-to-sample discriminations that could have established four, 3-member stimulus classes. In Group EA, four other students were trained with discriminations that could have established four, 5-member classes. Neither group received derived-relations testing; instead, adduction was assessed immediately after the baseline discriminations were learned. The adduction assessment required participants to derive the untested CA (Group CA) or EA (Group EA) equivalence relations and combine them with their already learned math skills. All participants in Group CA showed above 90% accuracy during the adduction assessment, whereas only one of four Group EA participants responded in that manner. These results extend adduction to untested equivalence relations and clarify the environmental conditions under which such adduction is less likely to occur (i.e., with larger relational networks). Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Stimulus Novelty Energizes Actions in the Absence of Explicit Reward.

    Directory of Open Access Journals (Sweden)

    Raphael Koster

    Full Text Available Novelty seeking has been tied to impulsive choice and biased value based choice. It has been postulated that novel stimuli should trigger more vigorous approach and exploration. However, it is unclear whether stimulus novelty can enhance simple motor actions in the absence of explicit reward, a necessary condition for energizing approach and exploration in an entirely unfamiliar situation. In this study human subjects were cued to omit or perform actions in form of button presses by novel or familiar images. We found that subjects' motor actions were faster when cued by a novel compared to a familiar image. This facilitation by novelty was strongest when the delay between cue and action was short, consistent with a link between novelty and impulsive choices. The facilitation of reaction times by novelty was correlated across subjects with trait novelty seeking as measured in the Tridimensional Personality Questionnaire. However, this li between high novelty-seeking and action facilitation was driven by trials with a long delay between cue and action. This prolonged time window of energization following novelty could hint at a mechanistic underpinning of enhanced vigour for approach and exploration frequently postulated for novelty seeking humans. In conclusion, we show that stimulus novelty enhances the speed of a cued motor action. We suggest this is likely to reflect an adaptation to changing environments but may also provide a source of maladaptive choice and impulsive behaviour.

  20. Inhibition of eye blinking reveals subjective perceptions of stimulus salience.

    Science.gov (United States)

    Shultz, Sarah; Klin, Ami; Jones, Warren

    2011-12-27

    Spontaneous eye blinking serves a critical physiological function, but it also interrupts incoming visual information. This tradeoff suggests that the inhibition of eye blinks might constitute an adaptive reaction to minimize the loss of visual information, particularly information that a viewer perceives to be important. To test this hypothesis, we examined whether the timing of blink inhibition, during natural viewing, is modulated between as well as within tasks, and also whether the timing of blink inhibition varies as a function of viewer engagement and stimulus event type. While viewing video scenes, we measured the timing of blinks and blink inhibition, as well as visual scanning, in a group of typical two-year-olds, and in a group of two-year-olds known for attenuated reactivity to affective stimuli: toddlers with Autism Spectrum Disorders (ASD). Although both groups dynamically adjusted the timing of their blink inhibition at levels greater than expected by chance, they inhibited their blinking and shifted visual fixation differentially with respect to salient onscreen events. Moreover, typical toddlers inhibited their blinking earlier than toddlers with ASD, indicating active anticipation of the unfolding of those events. These findings indicate that measures of blink inhibition can serve as temporally precise markers of perceived stimulus salience and are useful quantifiers of atypical processing of social affective signals in toddlers with ASD.

  1. Stimulus-Specific Transcriptional Regulation Within the p53 Network

    Science.gov (United States)

    Donner, Aaron Joseph; Hoover, Jennifer Michelle; Szostek, Stephanie Aspen; Espinosa, Joaquín Maximiliano

    2010-01-01

    The p53 transcriptional network is composed of hundreds of effector genes involved in varied stress-response pathways, including cell cycle arrest and apoptosis. It is not clear how distinct p53 target genes are differentially activated to trigger stress-specific biological responses. We analyzed the p53 transcriptional program upon activation by two DNA-damaging agents, UVC and doxorubicin, versus the non-genotoxic molecule Nutlin-3. In colorectal cancer cells, UVC triggers apoptosis, doxorubicin induces transient cell cycle arrest followed by apoptosis, and Nutlin-3 leads to cell cycle arrest with no significant apoptosis. Quantitative gene expression analysis allowed us to group p53 target genes into three main classes according to their activation profiles in each scenario. The CDK-inhibitor p21 was classified as a Class I gene, being significantly activated under cell cycle arrest conditions (i.e., doxorubicin and Nutlin-3) but not during UVC-induced apoptosis. Chromatin immunoprecipitation analysis of the p21 locus indicates that the level of p53-dependent transcription is determined by the effects of stimulus-specific transcriptional coregulators acting downstream of p53 binding and histone acetylation. In particular, our analysis indicates that the subunits of the CDK-module of the human Mediator complex function as stimulus-specific positive coregulators of p21 transcription. PMID:17957141

  2. Effects of ayahuasca on binocular rivalry with dichoptic stimulus alternation.

    Science.gov (United States)

    Frecska, E; White, K D; Luna, L E

    2004-04-01

    During binocular rivalry, two incompatible images are presented to each eye and these monocular stimuli compete for perceptual dominance, with one pattern temporarily suppressed from awareness. One variant of stimulus presentation in binocular rivalry experiments is dichoptic stimulus alternation (DSA), when stimuli are applied to the eyes in rapid reversals. There is preliminary report that in contrast with healthy controls, schizophrenic patients can maintain binocular rivalry even at very high DSA rates. The study was undertaken to investigate whether binocular rivalry survives high rates of DSA induced by the South American hallucinogenic beverage ayahuasca. Ten individuals who were participating in ayahuasca ceremonials were requested to volunteer for binocular rivalry tests (DSA=0, 3.75, 7.5, 15 and 30 Hz) without and after drinking the brew. Ingestion of ayahuasca increased mean dominance periods both in standard binocular rivalry conditions (no DSA) and tests with DSA. At higher DSA rates (15 and 30 Hz) the total length of dominance periods was longer on the brew. It is discussed that ayahuasca-induced survival of binocular rivalry at high DSA rates may be related to slow visual processing and increased mean dominance periods may result from hallucinogen-induced alteration of gamma oscillations in the visual pathways.

  3. Flavor Identification and Intensity: Effects of Stimulus Context.

    Science.gov (United States)

    Hallowell, Emily S; Parikh, Roshan; Veldhuizen, Maria G; Marks, Lawrence E

    2016-03-01

    Two experiments presented oral mixtures containing different proportions of the gustatory flavorant sucrose and an olfactory flavorant, either citral (Experiment 1) or lemon (Experiment 2). In 4 different sessions of each experiment, subjects identified each mixture as "mostly sugar" or "mostly citrus/lemon" or rated the perceived intensities of the sweet and citrus components. Different sessions also presented the mixtures in different contexts, with mixtures containing relatively high concentrations of sucrose or citral/lemon presented more often (skew sucrose or skew citral/lemon). As expected, in both experiments, varying stimulus context affected both identification and perceived intensity: Skewing to sucrose versus citral/lemon decreased the probability of identifying the stimuli as "mostly sugar" and reduced the ratings of sweet intensity relative to citrus intensity. Across both contextual conditions of both experiments, flavor identification associated closely with the ratio of the perceived sweet and citrus intensities. The results accord with a model, extrapolated from signal-detection theory, in which sensory events are represented as multisensory-multidimensional distributions in perceptual space. Changing stimulus context can shift the locations of the distributions relative to response criteria, Decision rules guide judgments based on both sensory events and criteria, these rules not necessarily being identical in tasks of identification and intensity rating. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Parietal cortex mediates perceptual Gestalt grouping independent of stimulus size.

    Science.gov (United States)

    Grassi, Pablo R; Zaretskaya, Natalia; Bartels, Andreas

    2016-06-01

    The integration of local moving elements into a unified gestalt percept has previously been linked to the posterior parietal cortex. There are two possible interpretations for the lack of involvement of other occipital regions. The first is that parietal cortex is indeed uniquely functionally specialized to perform grouping. Another possibility is that other visual regions can perform grouping as well, but that the large spatial separation of the local elements used previously exceeded their neurons' receptive field (RF) sizes, preventing their involvement. In this study we distinguished between these two alternatives. We measured whole-brain activity using fMRI in response to a bistable motion illusion that induced mutually exclusive percepts of either an illusory global Gestalt or of local elements. The stimulus was presented in two sizes, a large version known to activate IPS only, and a version sufficiently small to fit into the RFs of mid-level dorsal regions such as V5/MT. We found that none of the separately localized motion regions apart from parietal cortex showed a preference for global Gestalt perception, even for the smaller version of the stimulus. This outcome suggests that grouping-by-motion is mediated by a specialized size-invariant mechanism with parietal cortex as its anatomical substrate. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Discriminative stimulus properties of lysergic acid diethylamide in the monkey.

    Science.gov (United States)

    Nielsen, E B

    1985-07-01

    Four monkeys (Cercopithecus aethiops) were trained to discriminate 0.06 mg/kg of lysergic acid diethylamide (LSD) from saline in a two-key task in which correct responding was reinforced with food under a fixed ratio 32 schedule. The ED50 of LSD was 0.011 mg/kg. The nonhallucinogenic ergot, lisuride, and the hallucinogen, 5-methoxy-N,N-dimethyltryptamine, substituted completely for LSD (ED50 values were 0.0098 and 0.45 mg/kg, respectively). Mescaline (1-40 mg/kg), d-amphetamine (0.1-0.625 mg/kg) and apomorphine (0.1-0.5 mg/kg) did not substitute for LSD. In antagonism testing with ketanserin (1-10 mg/kg) or pirenperone (0.025 and 0.05 mg/kg), only the highest dose of pirenperone attenuated the LSD stimulus effect (to 55%). A 0.1-mg/kg dose of pirenperone produced nonresponding in three of four animals. The LSD cue was unaffected by clozapine (1 and 2 mg/kg), haloperidol (0.1 mg/kg) and pizotifen (0.6-1.8 mg/kg). The fact that lisuride does not readily cause hallucinations in humans, but yet substituted for LSD in primates, indicates that the LSD cue may not reflect the hallucinogenic properties of LSD. It is suggested that the LSD stimulus effect may depend on receptors (e.g., serotonergic) that, at the moment, are only poorly characterized.

  6. Toward Biofunctional Microneedles for Stimulus Responsive Drug Delivery.

    Science.gov (United States)

    Cahill, Ellen M; O'Cearbhaill, Eoin D

    2015-07-15

    Microneedles have recently been adopted for use as a painless and safe method of transdermal therapeutic delivery through physically permeating the stratum corneum. While microneedles create pathways to introduce drugs, they can also act as conduits for biosignal sensing. Here, we explore the development of microneedles as both biosensing and drug delivery platforms. Microneedle sensors are being developed for continuous monitoring of biopotentials and bioanalytes through the use of conductive and electrochemically reactive biomaterials. The range of therapeutics being delivered through microneedle devices has diversified, while novel bioabsorbable microneedles are undergoing first-in-human clinical studies. We foresee that future microneedle platform development will focus on the incorporation of biofunctional materials, designed to deliver therapeutics in a stimulus responsive fashion. Biofunctional microneedle patches will require improved methods of attaching to and conforming to epithelial tissues in dynamic environments for longer periods of time and thus present an assortment of new design challenges. Through the evolution of biomaterial development and microneedle design, biofunctional microneedles are proposed as a next generation of stimulus responsive drug delivery systems.

  7. Visual stimulus presentation using fiber optics in the MRI scanner.

    Science.gov (United States)

    Huang, Ruey-Song; Sereno, Martin I

    2008-03-30

    Imaging the neural basis of visuomotor actions using fMRI is a topic of increasing interest in the field of cognitive neuroscience. One challenge is to present realistic three-dimensional (3-D) stimuli in the subject's peripersonal space inside the MRI scanner. The stimulus generating apparatus must be compatible with strong magnetic fields and must not interfere with image acquisition. Virtual 3-D stimuli can be generated with a stereo image pair projected onto screens or via binocular goggles. Here, we describe designs and implementations for automatically presenting physical 3-D stimuli (point-light targets) in peripersonal and near-face space using fiber optics in the MRI scanner. The feasibility of fiber-optic based displays was demonstrated in two experiments. The first presented a point-light array along a slanted surface near the body, and the second presented multiple point-light targets around the face. Stimuli were presented using phase-encoded paradigms in both experiments. The results suggest that fiber-optic based displays can be a complementary approach for visual stimulus presentation in the MRI scanner.

  8. Does bimodal stimulus presentation increase ERP components usable in BCIs?

    Science.gov (United States)

    Thurlings, Marieke E.; Brouwer, Anne-Marie; Van Erp, Jan B. F.; Blankertz, Benjamin; Werkhoven, Peter J.

    2012-08-01

    Event-related potential (ERP)-based brain-computer interfaces (BCIs) employ differences in brain responses to attended and ignored stimuli. Typically, visual stimuli are used. Tactile stimuli have recently been suggested as a gaze-independent alternative. Bimodal stimuli could evoke additional brain activity due to multisensory integration which may be of use in BCIs. We investigated the effect of visual-tactile stimulus presentation on the chain of ERP components, BCI performance (classification accuracies and bitrates) and participants’ task performance (counting of targets). Ten participants were instructed to navigate a visual display by attending (spatially) to targets in sequences of either visual, tactile or visual-tactile stimuli. We observe that attending to visual-tactile (compared to either visual or tactile) stimuli results in an enhanced early ERP component (N1). This bimodal N1 may enhance BCI performance, as suggested by a nonsignificant positive trend in offline classification accuracies. A late ERP component (P300) is reduced when attending to visual-tactile compared to visual stimuli, which is consistent with the nonsignificant negative trend of participants’ task performance. We discuss these findings in the light of affected spatial attention at high-level compared to low-level stimulus processing. Furthermore, we evaluate bimodal BCIs from a practical perspective and for future applications.

  9. Millennial reconstructions: what can we learn from limited proxy data?

    Science.gov (United States)

    Annan, J. D.; Hargreaves, J. C.

    2011-12-01

    Reconstructions of the past millennium can help us to understand recent and future climate change, by placing the recent anthropogenically-forced changes in the context of natural variability. Proxy data prior to the instrumental era are, however, extremely limited, which raises the question of how well we can truly hope to understand the past. Until recently, temperature reconstructions over the past millennium have primarily used statistical regression-based methods, however approaches using data assimilation methodology (in which observational data are blended with dynamical climate models) have shown great potential and are being increasingly adopted. However, rigorous validation of these methods has been somewhat limited. Here we will present the results of some investigations into the performance, and the potential, of data assimilation approaches to estimate the climate state. We use a massive ensemble of the LOVECLIM model to generate precise results which (through being formally optimal) may be considered an upper bound on the performance of more realistic approaches. We show that the limited precision and volume of data places a severe constraint on our ability to reliably reconstruct past climate variability, especially prior to the middle of the last millennium.

  10. Identification of climatic state with limited proxy data

    Directory of Open Access Journals (Sweden)

    J. D. Annan

    2012-07-01

    Full Text Available We investigate the identifiability of the climate by limited proxy data. We test a data assimilation approach through perfect model pseudoproxy experiments, using a simple likelihood-based weighting based on the particle filtering process. Our experimental set-up enables us to create a massive 10 000-member ensemble at modest computational cost, thus enabling us to generate statistically robust results. We find that the method works well when data are sparse and imprecise, but in this case the reconstruction has a rather low accuracy as indicated by residual RMS errors. Conversely, when data are relatively plentiful and accurate, the estimate tracks the target closely, at least when considering the hemispheric mean. However, in this case, our prior ensemble size of 10 000 appears to be inadequate to correctly represent the true posterior, and the regional performance is poor. Using correlations to assess performance gives a more encouraging picture, with significant correlations ranging from about 0.3 when data are sparse to values over 0.7 when data are plentiful, but the residual RMS errors are substantial in all cases. Our results imply that caution is required in interpreting climate reconstructions, especially when considering the regional scale, as skill on this basis is markedly lower than on the large scale of hemispheric mean temperature.

  11. Medieval horse stable; the results of multi proxy interdisciplinary research.

    Science.gov (United States)

    Dejmal, Miroslav; Lisá, Lenka; Fišáková Nývltová, Miriam; Bajer, Aleš; Petr, Libor; Kočár, Petr; Kočárová, Romana; Nejman, Ladislav; Rybníček, Michal; Sůvová, Zdenka; Culp, Randy; Vavrčík, Hanuš

    2014-01-01

    A multi proxy approach was applied in the reconstruction of the architecture of Medieval horse stable architecture, the maintenance practices associated with that structure as well as horse alimentation at the beginning of 13th century in Central Europe. Finally, an interpretation of the local vegetation structure along Morava River, Czech Republic is presented. The investigated stable experienced two construction phases. The infill was well preserved and its composition reflects maintenance practices. The uppermost part of the infill was composed of fresh stabling, which accumulated within a few months at the end of summer. Horses from different backgrounds were kept in the stable and this is reflected in the results of isotope analyses. Horses were fed meadow grasses as well as woody vegetation, millet, oat, and less commonly hemp, wheat and rye. Three possible explanations of stable usage are suggested. The stable was probably used on a temporary basis for horses of workers employed at the castle, courier horses and horses used in battle.

  12. Music Therapy by Proxy: Using Humanised Images in Song

    Directory of Open Access Journals (Sweden)

    Carol Chambers

    2013-07-01

    Full Text Available Developing awareness, exploration and expression of emotionally sensitive issues can be difficult for some clients in music therapy. They may find it hard to express emotion through improvised music and may turn instead to the perceived security of the repetition of known songs.This paper presents the results from a completed research PhD, a qualitative case study based on naturalistic clinical practice, which examined the song choices of one woman in a medium-secure forensic unit over the three-year course of her music therapy. A descriptive narrative account was subjected to analysis according to a modified form of therapeutic narrative analysis (Aldridge and Aldridge 2002, resulting in the abstraction of a series of generative metaphoric images, framed within a chronological series of events. Crucially, these images were found to be humanised figures, yet they were also emotionally decentred or depersonalised. When approached from the philosophical and methodological perspective of behaviourism, which views these as conditioned responses associating music with life experiences as part of a process of developing self-identity, such images can be seen to provide an unspoken voice for the client’s feelings to be expressed in a manner that is personally revealing, socially acceptable, culturally accessible and therapeutically constructive.I assert that using these third-person characters as a form of proxy facilitates mutual reference and experimentation, and places music firmly at the heart of a socially constructed process of music therapy.

  13. A Rare Reason of Hyperinsulinism: Munchausen Syndrome by Proxy.

    Science.gov (United States)

    Akın, Onur; Yeşilkaya, Ediz; Sari, Erkan; Akar, Çağdaş; Başbozkurt, Gökalp; Macit, Enis; Aydin, Ibrahim; Taşlipinar, Abdullah; Gül, Hüsamettin

    2016-01-01

    Hyperinsulinism, one of the most important causes of hypoglycaemia, can be congenital or acquired. Rarely, drug toxicity can be a reason for hyperinsulinism. In the context of Munchausen syndrome by proxy (MSP), toxicity usually occurs in children due to drug administration by a parent or caregiver. A 7-year-old girl was referred to our department due to a hyperglycaemic period and hypoglycaemic episodes. On admission, gliclazide was initiated due to her hyperglycaemia, which we attributed to maturity onset diabetes of the young. However, during follow-up, hypoglycaemic levels were detected. Despite cessation of gliclazide, hypoglycaemic seizures occurred. Even with the medications administered, hypoglycaemia could not be prevented. During follow-up, the mother's affect, characterized by anxiety and interest in her daughter's medical care, appeared discordant with the situation. Due to our suspicion of MSP, we discovered toxic levels of gliclazide in the blood and urine samples which had been sent to the toxicology laboratory to search for hypoglycaemic agents. The patient was isolated, and all medications were stopped. After isolation, her hypoglycaemia disappeared, and she became hyperglycaemic (250 mg/dl). Physicians should consider the possibility of MSP in hyperinsulinaemic patients with discordant laboratory results and clinical symptoms, even if the child's parents display great concern. © 2016 S. Karger AG, Basel.

  14. Munchausen syndrome by proxy mimicking as Gaucher disease.

    Science.gov (United States)

    Al-Owain, Mohammed; Al-Zaidan, Hamad; Al-Hashem, Amal; Kattan, Hoda; Al-Dowaish, Abdullah

    2010-08-01

    Although rare, Munchausen syndrome by proxy (MBP) is a potentially life-threatening form of child abuse. Here, we report a 19-month-old female infant who presented with hepatosplenomegaly, anemia, thrombocytopenia, and recurrent septicemia. She was initially thought to have myelodysplastic syndrome. Further hematological and immunological investigations revealed no cause. beta-Glucosylceramidase enzyme activity on dried blood spot was suggestive of Gaucher disease. However, the enzyme level on cultured skin fibroblast was not consistent with Gaucher disease. The first hint about MBP was the recurrent sepsis with numerous gram negative rods. Furthermore, the mother's behavior and health history raised our suspicion about MBP. The child showed significant improvement after she was separated from the mother for a week. Finally, the mother confessed that she was spitting in local herbs and injecting it into the central line. This is, to our knowledge, the first report of MBP resembling in its presentation Gaucher disease. This case should alert the general and specialized pediatricians about MBP, as it may mimic metabolic diseases like Gaucher disease.

  15. Severe hypernatremia in a hospitalized child: munchausen by proxy.

    Science.gov (United States)

    Su, Erik; Shoykhet, Michael; Bell, Michael J

    2010-10-01

    An 8-week-old infant presented to a referring institution with profuse diarrhea and infectious enteritis for 1 week. He was initially treated for suspected Salmonella spp. sepsis and meningitis, because the organism was found in the stool, but the child's illness progressed, manifested by paroxysmal profuse diarrhea and increased urine output. After several weeks, he suffered a sagittal venous thrombosis and intracranial hemorrhage. Subsequently the child was transferred to a tertiary center for intestinal evaluation. The patient's diarrhea and excessive diuresis resolved, and his sodium normalized soon after transfer. Four days later, however, after his mother arrived, he immediately developed severe hypernatremia (serum sodium concentration [Na(+)] = 214 mEq/L), with resumption of diarrhea and excessive diuresis. A gastric aspirate during the crisis demonstrated an extremely high sodium content, [Na(+)] = 1416 mEq/L, consistent with salt intoxication. Surveillance of the mother revealed that she manipulated the indwelling nasogastric tube; confronted, she admitted to salt administration. This case describes one of the ways that Munchausen syndrome by proxy can manifest with profound neurologic sequelae, and highlights the need for close observation and swift intervention when sufficient cause is present. Copyright © 2010 Elsevier Inc. All rights reserved.

  16. Cognitive-Behavioral Therapy for Body Dysmorphic Disorder by Proxy.

    Science.gov (United States)

    Greenberg, Jennifer L; Mothi, Suraj Sarvode; Wilhelm, Sabine

    2016-07-01

    Body dysmorphic disorder (BDD) is a distressing or impairing preoccupation with a perceived defect in physical appearance. BDD by proxy (BDDBP) is a significant but understudied variant of BDD in which the primary preoccupation involves perceived imperfections of another person. Like BDD, individuals with BDDBP engage in time-consuming rituals to "fix" the other person's appearance or alleviate distress. Avoidance is common and the impact of BDDBP on social functioning is profound. Cognitive-behavioral therapy (CBT) is the best-studied and most promising psychological treatment for BDD, but no studies have examined its generalizability to the BDDBP variant. We tested feasibility, acceptability, and treatment outcome of CBT modified for BDDBP in a sample of 6 adults with primary BDDBP. Treatment was delivered in weekly individual sessions over 12-20weeks. Mean symptom severity (BDDBP-YBOCS) dropped from the moderately severe range at pretreatment to the subclinical range at posttreatment, t(6)=10.7, p<.001, d=3.3. One hundred percent of treatment completers were responders (≥30% reduction in BDDBP-YBOCS). Insight also improved. Treatment gains were maintained at 3-month follow-up. To our knowledge, this represents the first treatment study for BDDBP. Copyright © 2016. Published by Elsevier Ltd.

  17. A brief intervention for preparing ICU families to be proxies: A phase I study.

    Science.gov (United States)

    Turnbull, Alison E; Chessare, Caroline M; Coffin, Rachel K; Needham, Dale M

    2017-01-01

    Family members of critically ill patients report high levels of conflict with clinicians, have poor understanding of prognosis, struggle to make decisions, and experience substantial symptoms of anxiety, depression, and post-traumatic stress regardless of patient survival status. Efficient interventions are needed to prepare these families to act as patient proxies. To assess a brief "patient activation" intervention designed to set expectations and prepare families of adult intensive care unit (ICU) patients to communicate effectively with the clinical team. Phase I study of acceptability and immediate side effects. 122 healthcare proxies of 111 consecutive patients with a stay of ≥24 hours in the Johns Hopkins Hospital Medical ICU (MICU), in Baltimore, Maryland. Reading aloud to proxies from a booklet (Flesch-Kincard reading grade level 3.8) designed with multidisciplinary input including from former MICU proxies. Enrolled proxies had a median age of 51 years old with 83 (68%) female, and 55 (45%) African-American. MICU mortality was 18%, and 37 patients (33%) died in hospital or were discharged to hospice. Among proxies 98% (95% CI: 94% - 100%) agreed or strongly agreed that the intervention was appropriate, 98% (95% CI: 92% - 99%) agreed or strongly agreed that it is important for families to know the information in the booklet, and 54 (44%, 95% CI 35%- 54%) agreed or strongly agreed that parts of the booklet are upsetting. Upset vs. non-upset proxies were not statistically or substantially different in terms of age, sex, education level, race, relation to the patient, or perceived decision-making authority. This patient activation intervention was acceptable and important to nearly all proxies. Frequently, the intervention was simultaneously rated as both acceptable/important and upsetting. Proxies who rated the intervention as upsetting were not identifiable based on readily available proxy or patient characteristics.

  18. A Multi-Component Proxy for OH Variability Measured from Space: Evaluation and Evolution

    Science.gov (United States)

    Murray, L. T.; Fiore, A. M.; Valin, L. C.

    2014-12-01

    Observed changes in the decay rate of methyl chloroform (MCF; CH3CCl3) have been the traditional top-down constraint for variability in tropospheric abundances of the hydroxyl radical (OH), and thereby the oxidative capacity of the atmosphere. However, as atmospheric MCF concentrations approach detection limits following its ban under the Montréal Protocol, it is necessary to identify new proxies for global OH and its variability. We present here a novel proxy for tropospheric OH using convolved observations of total and tropospheric columns of ozone, water vapor, NO2, and CO, available from the Aura and Aqua satellites in the NASA Earth Observing System constellation. Derived from photochemical steady-state assumptions, the satellite proxy generates spatiotemporally coherent monthly percent anomalies in column OH for Oct. 2004 through Sept. 2012. We demonstrate that the temporal evolution of the globally integrated signal is statistically consistent with changes inferred by the MCF decay rate during this period. The magnitude of interannual variability in the satellite OH proxy is smaller than that from MCF, more consistent with global chemical transport models (CTMs). We evaluate the proxy by comparing to 9-year hind-cast simulations of the GEOS-Chem global CTM driven by MERRA reanalysis meteorology at 2° x 2.5° horizontal resolution, and find that the satellite proxy correlates with the airmass-weighted tropospheric monthly mean OH anomalies (R = 0.6; n = 96 months). The satellite proxy and model simulations indicate regional-scale coherent OH anomalies for many regions and seasons; where discrepancies occur, we highlight possible causes. We present a source attribution of the spatial and temporal patterns in the satellite OH proxy, informed by the individual components of the satellite proxy, a series of zero-emission sensitivity simulations with GEOS-Chem, and independent proxies for major modes of climate variability.

  19. A brief intervention for preparing ICU families to be proxies: A phase I study.

    Directory of Open Access Journals (Sweden)

    Alison E Turnbull

    Full Text Available Family members of critically ill patients report high levels of conflict with clinicians, have poor understanding of prognosis, struggle to make decisions, and experience substantial symptoms of anxiety, depression, and post-traumatic stress regardless of patient survival status. Efficient interventions are needed to prepare these families to act as patient proxies.To assess a brief "patient activation" intervention designed to set expectations and prepare families of adult intensive care unit (ICU patients to communicate effectively with the clinical team.Phase I study of acceptability and immediate side effects.122 healthcare proxies of 111 consecutive patients with a stay of ≥24 hours in the Johns Hopkins Hospital Medical ICU (MICU, in Baltimore, Maryland.Reading aloud to proxies from a booklet (Flesch-Kincard reading grade level 3.8 designed with multidisciplinary input including from former MICU proxies.Enrolled proxies had a median age of 51 years old with 83 (68% female, and 55 (45% African-American. MICU mortality was 18%, and 37 patients (33% died in hospital or were discharged to hospice. Among proxies 98% (95% CI: 94% - 100% agreed or strongly agreed that the intervention was appropriate, 98% (95% CI: 92% - 99% agreed or strongly agreed that it is important for families to know the information in the booklet, and 54 (44%, 95% CI 35%- 54% agreed or strongly agreed that parts of the booklet are upsetting. Upset vs. non-upset proxies were not statistically or substantially different in terms of age, sex, education level, race, relation to the patient, or perceived decision-making authority.This patient activation intervention was acceptable and important to nearly all proxies. Frequently, the intervention was simultaneously rated as both acceptable/important and upsetting. Proxies who rated the intervention as upsetting were not identifiable based on readily available proxy or patient characteristics.

  20. An Excel Workbook for Identifying Redox Processes in Ground Water

    Science.gov (United States)

    Jurgens, Bryant C.; McMahon, Peter B.; Chapelle, Francis H.; Eberts, Sandra M.

    2009-01-01

    The reduction/oxidation (redox) condition of ground water affects the concentration, transport, and fate of many anthropogenic and natural contaminants. The redox state of a ground-water sample is defined by the dominant type of reduction/oxidation reaction, or redox process, occurring in the sample, as inferred from water-quality data. However, because of the difficulty in defining and applying a systematic redox framework to samples from diverse hydrogeologic settings, many regional water-quality investigations do not attempt to determine the predominant redox process in ground water. Recently, McMahon and Chapelle (2008) devised a redox framework that was applied to a large number of samples from 15 principal aquifer systems in the United States to examine the effect of redox processes on water quality. This framework was expanded by Chapelle and others (in press) to use measured sulfide data to differentiate between iron(III)- and sulfate-reducing conditions. These investigations showed that a systematic approach to characterize redox conditions in ground water could be applied to datasets from diverse hydrogeologic settings using water-quality data routinely collected in regional water-quality investigations. This report describes the Microsoft Excel workbook, RedoxAssignment_McMahon&Chapelle.xls, that assigns the predominant redox process to samples using the framework created by McMahon and Chapelle (2008) and expanded by Chapelle and others (in press). Assignment of redox conditions is based on concentrations of dissolved oxygen (O2), nitrate (NO3-), manganese (Mn2+), iron (Fe2+), sulfate (SO42-), and sulfide (sum of dihydrogen sulfide [aqueous H2S], hydrogen sulfide [HS-], and sulfide [S2-]). The logical arguments for assigning the predominant redox process to each sample are performed by a program written in Microsoft Visual Basic for Applications (VBA). The program is called from buttons on the main worksheet. The number of samples that can be analyzed

  1. The Redox Flow System for solar photovoltaic energy storage

    Science.gov (United States)

    Odonnell, P.; Gahn, R. F.; Pfeiffer, W.

    1976-01-01

    The interfacing of a Solar Photovoltaic System and a Redox Flow System for storage was workable. The Redox Flow System, which utilizes the oxidation-reduction capability of two redox couples, in this case iron and titanium, for its storage capacity, gave a relatively constant output regardless of solar activity so that a load could be run continually day and night utilizing the sun's energy. One portion of the system was connected to a bank of solar cells to electrochemically charge the solutions, while a separate part of the system was used to electrochemically discharge the stored energy.

  2. Redox chemistry of americium in nitric acid media

    Energy Technology Data Exchange (ETDEWEB)

    Picart, S.; Jobelin, I.; Armengol, G.; Adnet, JM

    2004-07-01

    The redox properties of the actinides are very important parameters for speciation studies and spent nuclear fuel reprocessing based on liquid-liquid extraction of actinides at different oxidation states (as in the Purex or Sesame process). They are also very useful for developing analytical tools including coulometry and redox titration. This study addressed the americium(IV)/americium(III) and americium(VI)/americium(V) redox couples, focusing on exhaustive acquisition of the thermodynamic and kinetic parameters of americium oxidation at an electrode in a complexing nitric acid medium. (authors)

  3. Disentangling interfacial redox processes of proteins by SERR spectroscopy.

    Science.gov (United States)

    Murgida, Daniel H; Hildebrandt, Peter

    2008-05-01

    Surface-enhanced resonance-Raman spectroelectrochemistry represents a powerful approach for studying the structure and reaction dynamics of redox proteins immobilized on biocompatible electrodes in fundamental and applied sciences. Using this approach it has been recently shown that electric fields of biologically relevant magnitude are able to influence crucial parameters for the functioning of a variety of soluble and membrane bound heme proteins. Electric field effects discussed in this tutorial review include modulation of redox potentials, reorganization energies, protein dynamics and redox-linked structural changes.

  4. Glutathione redox potential in the mitochondrial intermembrane space is linked to the cytosol and impacts the Mia40 redox state

    Science.gov (United States)

    Kojer, Kerstin; Bien, Melanie; Gangel, Heike; Morgan, Bruce; Dick, Tobias P; Riemer, Jan

    2012-01-01

    Glutathione is an important mediator and regulator of cellular redox processes. Detailed knowledge of local glutathione redox potential (EGSH) dynamics is critical to understand the network of redox processes and their influence on cellular function. Using dynamic oxidant recovery assays together with EGSH-specific fluorescent reporters, we investigate the glutathione pools of the cytosol, mitochondrial matrix and intermembrane space (IMS). We demonstrate that the glutathione pools of IMS and cytosol are dynamically interconnected via porins. In contrast, no appreciable communication was observed between the glutathione pools of the IMS and matrix. By modulating redox pathways in the cytosol and IMS, we find that the cytosolic glutathione reductase system is the major determinant of EGSH in the IMS, thus explaining a steady-state EGSH in the IMS which is similar to the cytosol. Moreover, we show that the local EGSH contributes to the partially reduced redox state of the IMS oxidoreductase Mia40 in vivo. Taken together, we provide a comprehensive mechanistic picture of the IMS redox milieu and define the redox influences on Mia40 in living cells. PMID:22705944

  5. High-resolution multi-proxy reconstruction of Lake Ighiel (Western Carpathians, Romania): processes and controlling factors of lacustrine dynamics during the mid and late Holocene

    Science.gov (United States)

    Haliuc, Aritina; Veres, Daniel; Hubay, Katalin; Begy, Robert; Brauer, Achim; Hutchinson, Simon; Braun, Mihaly

    2016-04-01

    Concerns about current and prospective environmental change have increased the interest in past climate variability and its impact on the bio-hydro-atmosphere and human society. Acting as high-resolution terrestrial archives, lacustrine sediments are the result of the complex interaction between internal and external forcing and an important tool in efforts to resolve questions related to the palaeoclimatic and palaeoenvironmental conditions of the recent past. Here we discuss a new, high-resolution sedimentary record from the Romanian Carpathians (central-eastern Europe). Lake Ighiel (46° 10'50"N, 23° 22'00"E) is a small lake located in a mid-altitude mountain belt (Trascau Mountains) at an altitude of 924 m ( lake maximum depth 9 m; catchment area 487 ha). We employ detailed 210Pb and 14C dating coupled with high-resolution X-ray fluorescence scanning (μ-XRF) measurements, long-core sedimentary logging, environmental magnetic proxies (susceptibility, natural and induced remanences) in an attempt to trace the 6000 years evolution of lake-catchment system. More specifically, we discuss: i) the temporal evolution of the main sedimentation phases of the lake based on sedimentological, geochemical and magnetic proxies; ii) the amplitude and interplay of processes (natural and/or anthropogenic) controlling the depositional environment through time; iii) assess the contribution of each controlling factors and reconstruct the evolution of lacustrine system and palaeoclimate forcing using multivariate statistics. The sedimentary record can be divided into six phases based on alternating high and low detrital fluxes, oscillating lacustrine productivity and redox conditions. A series of detrital events (5200; 4800; 5400; 5250; 4500; 4050; 3800; 3500; 3250; 3050; 2650; 2350; 2250; 1400; 1100; 500; 100 cal yr BP) were identified by microfacies analyses and X-ray fluorescence scanning (μ-XRF) analysis. These events are reflected in most of the parameters and appear

  6. Relative contribution of expectancy and immediate arousal to the facilitatory effect of an auditory accessory stimulus

    Directory of Open Access Journals (Sweden)

    F. Del-Fava

    2004-08-01

    Full Text Available An auditory stimulus speeds up a digital response to a subsequent visual stimulus. This facilitatory effect has been related to the expectancy and the immediate arousal that would be caused by the accessory stimulus. The present study examined the relative contribution of these two influences. In a first and a third experiment a simple reaction time task was used. In a second and fourth experiment a go/no-go reaction time task was used. In each of these experiments, the accessory stimulus preceded the target stimulus by 200 ms for one group of male and female volunteers (G Fix. For another group of similar volunteers (G Var the accessory stimulus preceded the target stimulus by 200 ms in 25% of the trials, by 1000 ms in 25% of the trials and was not followed by the target stimulus in 50% of the trials (Experiments 1a and 1b or preceded the target stimulus by 200 ms in 6% of the trials and by 1000 ms in 94% of the trials (Experiments 2a and 2b. There was a facilitatory effect of the accessory stimulus for G Fix in the four experiments. There was also a facilitatory effect of the accessory stimulus at the 200-ms stimulus onset asynchrony for G Var in Experiments 1a and 1b but not in Experiments 2a and 2b. The facilitatory effects observed were larger in the go/no-go task than in the simple task. Taken together, these results suggest that expectancy is much more important than immediate arousal for the improvement of performance caused by an accessory stimulus.

  7. Bioelectrochemical probing of intracellular redox processes in living yeast cells—application of redox polymer wiring in a microfluidic environment

    DEFF Research Database (Denmark)

    Heiskanen, Arto; Coman, Vasile; Kostesha, Natalie

    2013-01-01

    utilizing a new double mediator system to map redox metabolism and screen for genetic modifications in Saccharomyces cerevisiae cells. The function of this new double mediator system based on menadione and osmium redox polymer (PVI-Os) is demonstrated. “Wiring” of S. cerevisiae cells using PVI-Os shows...... that microfluidic bioelectrochemical assays employing the menadione–PVI-Os double mediator system provides an effective means to conduct automated microbial assays. FigureMicrofluidic platform for bioelectrochemical assays using osmium redox polymer “wired” living yeast cells...

  8. Geochemical Proxies for Enhanced Process Control of Underground Coal Gasification

    Science.gov (United States)

    Kronimus, A.; Koenen, M.; David, P.; Veld, H.; van Dijk, A.; van Bergen, F.

    2009-04-01

    Underground coal gasification (UCG) represents a strategy targeting at syngas production for fuel or power generation from in-situ coal seams. It is a promising technique for exploiting coal deposits as an energy source at locations not allowing conventional mining under economic conditions. Although the underlying concept has already been suggested in 1868 and has been later on implemented in a number of field trials and even at a commercial scale, UCG is still facing technological barriers, impeding its widespread application. Field UCG operations rely on injection wells enabling the ignition of the target seam and the supply with oxidants (air, O2) inducing combustion (oxidative conditions). The combustion process delivers the enthalpy required for endothermic hydrogen production under reduction prone conditions in some distance to the injection point. The produced hydrogen - usually accompanied by organic and inorganic carbon species, e.g. CH4, CO, and CO2 - can then be retrieved through a production well. In contrast to gasification of mined coal in furnaces, it is difficult to measure the combustion temperature directly during UCG operations. It is already known that geochemical parameters such as the relative production gas composition as well as its stable isotope signature are related to the combustion temperature and, consequently, can be used as temperature proxies. However, so far the general applicability of such relations has not been proven. In order to get corresponding insights with respect to coals of significantly different rank and origin, four powdered coal samples covering maturities ranging from Ro= 0.43% (lignite) to Ro= 3.39% (anthracite) have been gasified in laboratory experiments. The combustion temperature has been varied between 350 and 900 ˚ C, respectively. During gasification, the generated gas has been captured in a cryo-trap, dried and the carbon containing gas components have been catalytically oxidized to CO2. Thereafter, the

  9. A Lattice-Based Identity-Based Proxy Blind Signature Scheme in the Standard Model

    Directory of Open Access Journals (Sweden)

    Lili Zhang

    2014-01-01

    Full Text Available A proxy blind signature scheme is a special form of blind signature which allowed a designated person called proxy signer to sign on behalf of original signers without knowing the content of the message. It combines the advantages of proxy signature and blind signature. Up to date, most proxy blind signature schemes rely on hard number theory problems, discrete logarithm, and bilinear pairings. Unfortunately, the above underlying number theory problems will be solvable in the postquantum era. Lattice-based cryptography is enjoying great interest these days, due to implementation simplicity and provable security reductions. Moreover, lattice-based cryptography is believed to be hard even for quantum computers. In this paper, we present a new identity-based proxy blind signature scheme from lattices without random oracles. The new scheme is proven to be strongly unforgeable under the standard hardness assumption of the short integer solution problem (SIS and the inhomogeneous small integer solution problem (ISIS. Furthermore, the secret key size and the signature length of our scheme are invariant and much shorter than those of the previous lattice-based proxy blind signature schemes. To the best of our knowledge, our construction is the first short lattice-based identity-based proxy blind signature scheme in the standard model.

  10. A Proxy Outcome Approach for Causal Effect in Observational Studies: A Simulation Study

    Directory of Open Access Journals (Sweden)

    Wenbin Liang

    2014-01-01

    Full Text Available Background. Known and unknown/unmeasured risk factors are the main sources of confounding effects in observational studies and can lead to false observations of elevated protective or hazardous effects. In this study, we investigate an alternative approach of analysis that is operated on field-specific knowledge rather than pure statistical assumptions. Method. The proposed approach introduces a proxy outcome into the estimation system. A proxy outcome possesses the following characteristics: (i the exposure of interest is not a cause for the proxy outcome; (ii causes of the proxy outcome and the study outcome are subsets of a collection of correlated variables. Based on these two conditions, the confounding-effect-driven association between the exposure and proxy outcome can then be measured and used as a proxy estimate for the effects of unknown/unmeasured confounders on the outcome of interest. Performance of this approach is tested by a simulation study, whereby 500 different scenarios are generated, with the causal factors of a proxy outcome and a study outcome being partly overlapped under low-to-moderate correlations. Results. The simulation results demonstrate that the conventional approach only led to a correct conclusion in 21% of the 500 scenarios, as compared to 72.2% for the alternative approach. Conclusion. The proposed method can be applied in observational studies in social science and health research that evaluates the health impact of behaviour and mental health problems.

  11. Redox shuttles for overcharge protection of lithium batteries

    Science.gov (United States)

    Amine, Khalil; Chen, Zonghai; Wang, Qingzheng

    2010-12-14

    The present invention is generally related to electrolytes containing novel redox shuttles for overcharge protection of lithium-ion batteries. The redox shuttles are capable of thousands hours of overcharge tolerance and have a redox potential at about 3-5.5 V vs. Li and particularly about 4.4-4.8 V vs. Li. Accordingly, in one aspect the invention provides electrolytes comprising an alkali metal salt; a polar aprotic solvent; and a redox shuttle additive that is an aromatic compound having at least one aromatic ring with four or more electronegative substituents, two or more oxygen atoms bonded to the aromatic ring, and no hydrogen atoms bonded to the aromatic ring; and wherein the electrolyte solution is substantially non-aqueous. Further there are provided electrochemical devices employing the electrolyte and methods of making the electrolyte.

  12. Redox Stable Anodes for Solid Oxide Fuel Cells

    Directory of Open Access Journals (Sweden)

    Guoliang eXiao

    2014-06-01

    Full Text Available Solid oxide fuel cells (SOFCs can convert chemical energy from the fuel directly to electrical energy with high efficiency and fuel flexibility. Ni-based cermets have been the most widely adopted anode for SOFCs. However, the conventional Ni-based anode has low tolerance to sulfur-contamination, is vulnerable to deactivation by carbon build-up (coking from direct oxidation of hydrocarbon fuels, and suffers volume instability upon redox cycling. Among these limitations, the redox instability of the anode is particularly important and has been intensively studied since the SOFC anode may experience redox cycling during fuel cell operations even with the ideal pure hydrogen as the fuel. This review aims to highlight recent progresses on improving redox stability of the conventional Ni-based anode through microstructure optimization and exploration of alternative ceramic-based anode materials.

  13. Redox metabolism abnormalities in autistic children associated with mitochondrial disease

    National Research Council Canada - National Science Library

    Frye, R E; Delatorre, R; Taylor, H; Slattery, J; Melnyk, S; Chowdhury, N; James, S J

    2013-01-01

    ...), including mitochondrial disease (MD) and abnormal redox metabolism. Despite the close connection between mitochondrial dysfunction and oxidative stress, the relation between MD and oxidative stress in children with ASD has not been studied...

  14. Redox therapy in neonatal sepsis: reasons, targets, strategy, and agents.

    Science.gov (United States)

    Bajčetić, Milica; Spasić, Snežana; Spasojević, Ivan

    2014-09-01

    Neonatal sepsis is one of the most fulminating conditions in neonatal intensive care units. Antipathogen and supportive care are administered routinely, but do not deliver satisfactory results. In addition, the efforts to treat neonatal sepsis with anti-inflammatory agents have generally shown to be futile. The accumulating data imply that intracellular redox changes intertwined into neonatal sepsis redox cycle represent the main cause of dysfunction of mitochondria and cells in neonatal sepsis. Our aim here is to support the new philosophy in neonatal sepsis treatment, which involves the integration of mechanisms that are responsible for cellular dysfunction and organ failure, the recognition of the most important targets, and the selection of safe agents that can stop the neonatal sepsis redox cycle by hitting the hot spots. Redox-active agents that could be beneficial for neonatal sepsis treatment according to these criteria include lactoferrin, interleukin 10, zinc and selenium supplements, ibuprofen, edaravone, and pentoxifylline.

  15. The Redox Potential of Hot Springs in Taiwan

    Directory of Open Access Journals (Sweden)

    Wen-Fu Chen Menghau Sung

    2009-01-01

    Full Text Available Scientists began acquiring the basic of geology, occurrence, water temperature and chemistry of hot springs in Tai wan over a century ago. However, data regarding redox potential and important redox couples still remains limited. This study explores the redox status of hot springs in Taiwan by measuring Eh in the field and by determining the concentrations of commonly found redox couples, i.e., O2/H2O, NO3 -/NH4 +, and HS-/SO4 -2. Water samples were collected at hot spring discharge pools or the heads of water wells using a pump. A total of 11 hot springs located at 9 different locations across Taiwan were surveyed.

  16. Redox Stratification of an Ancient Lake in Gale Crater, Mars

    Science.gov (United States)

    Hurowitz, J. A.; Grotzinger, J. P.; Fischer, W. W.; McLennan, S. M.; Milliken, R. E.; Stein, N.; Vasavada, A. R.; Blake, D. F.; DeHouck, E.; Eigenbrode, J. L.; Fairen, A. G.; Frydenvang, J.; Gellert, R.; Grant, J. A.; Gupta, S.; Herkenhoff, K. E.; Ming, D. W.; Rampe, E. B.; Schmidt, M. E.; Siebach, K. L.; Stack-Morgan, K.; Sumner, D. Y.; Wiens, R. C.

    2017-10-01

    The geochemistry, mineralogy, and sedimentology of mudstones studied by MSL-Curiosity indicate redox stratification of the lake within Gale crater and place new constraints on the habitability of the ancient Martian surface.

  17. Simulated airplane headache: a proxy towards identification of underlying mechanisms.

    Science.gov (United States)

    Bui, Sebastian Bao Dinh; Petersen, Torben; Poulsen, Jeppe Nørgaard; Gazerani, Parisa

    2017-12-01

    Airplane Headache (AH) occurs during flights and often appears as an intense, short lasting headache during take-off or landing. Reports are limited on pathological mechanisms underlying the occurrence of this headache. Proper diagnosis and treatments would benefit from identification of potential pathways involved in AH pathogenesis. This study aimed at providing a simulated airplane headache condition as a proxy towards identification of its underlying mechanisms. Fourteen participants including 7 volunteers suffering from AH and 7 healthy matched controls were recruited after meeting the diagnostic and safety criteria based on an approved study protocol. Simulation of AH was achieved by entering a pressure chamber with similar characteristics of an airplane flight. Selected potential biomarkers including salivary prostaglandin E2 (PGE2), cortisol, facial thermo-images, blood pressure, pulse, and saturation pulse oxygen (SPO) were defined and values were collected before, during and after flight simulation in the pressure chamber. Salivary samples were analyzed with ELISA techniques, while data analysis and statistical tests were handled with SPSS version 22.0. All participants in the AH-group experienced a headache attack similar to AH experience during flight. The non-AH-group did not experience any headaches. Our data showed that the values for PGE2, cortisol and SPO were significantly different in the AH-group in comparison with the non-AH-group during the flight simulation in the pressure chamber. The pressure chamber proved useful not only to provoke AH-like attack but also to study potential biomarkers for AH in this study. PGE2, and cortisol levels together with SPO presented dysregulation during the simulated AH-attack in affected individuals compared with healthy controls. Based on these findings we propose to use pressure chamber as a model to induce AH, and thus assess new potential biomarkers for AH in future studies.

  18. Fe-phyllosilicate redox cycling organisms from a redox transition zone in Hanford 300 Area sediments

    Directory of Open Access Journals (Sweden)

    Jason eBenzine

    2013-12-01

    Full Text Available Microorganisms capable of reducing or oxidizing structural iron (Fe in Fe-bearing phyllosilicate minerals were enriched and isolated from a subsurface redox transition zone at the Hanford 300 Area site in eastern Washington, USA. Both conventional and in situ i-chip enrichment strategies were employed. One Fe(III-reducing Geobacter (G. bremensis strain R1, Deltaproteobacteria and six Fe(II phyllosilicate-oxidizing isolates from the Alphaproteobacteria (Bradyrhizobium japonicum strains 22, is5, and in8p8, Betaproteobacteria (Cupriavidus necator strain A5-1, Dechloromonas agitata strain is5, and Actinobacteria (Nocardioides sp. strain in31 were recovered. The G. bremensis isolate grew by oxidizing acetate with the oxidized form of NAu-2 smectite as the electron acceptor. The Fe(II-oxidizers grew by oxidation of chemically reduced smectite as the energy source with nitrate as the electron acceptor. The Bradyrhizobium isolates could also carry out aerobic oxidation of biotite. This is the first report of the recovery of a Fe(II-oxidizing Nocardioides, and to date only one other Fe(II-oxidizing Bradyrhizobium is known. The 16S rRNA gene sequences of the isolates were similar to ones found in clone libraries from Hanford 300 sediments and groundwater, suggesting that such organisms may be present and active in situ. Whole genome sequencing of the isolates is underway, the results of which will enable comparative genomic analysis of mechanisms of extracellular phyllosilicate Fe redox metabolism, and facilitate development of techniques to detect the presence and expression of genes associated with microbial phyllosilicate Fe redox cycling in sediments.

  19. Redox State of the Neoarchean Earth Environment

    Science.gov (United States)

    Zerkle, Aubrey L.; Claire, Mark W.; Domagal-Goldman, Shawn; Farquhar, James; Poulton, Simon W.

    2011-01-01

    A Titan-like organic haze has been hypothesized for Earth's atmosphere prior to widespread surface oxygenation approx.2.45 billion years ago (Ga). We present a high-resolution record of quadruple sulfur isotopes, carbon isotopes, and Fe speciation from the approx.2.65-2.5 Ga Ghaap Group, South Africa, which suggest a linkage between organic haze and the biogeochemical cycling of carbon, sulfur, oxygen, and iron on the Archean Earth. These sediments provide evidence for oxygen production in microbial mats and localized oxygenation of surface waters. However, this oxygen production occurred under a reduced atmosphere which existed in multiple distinct redox states that correlate to changes in carbon and sulfur isotopes. The data are corroborated by photochemical model results that suggest bi-stable transitions between organic haze and haze-free atmospheric conditions in the Archean. These geochemical correlations also extend to other datasets, indicating that variations in the character of anomalous sulfur fractionation could provide insight into the role of carbon-bearing species in the reducing Archean atmosphere.

  20. Redox chemistry in the phosphorus biogeochemical cycle.

    Science.gov (United States)

    Pasek, Matthew A; Sampson, Jacqueline M; Atlas, Zachary

    2014-10-28

    The element phosphorus (P) controls growth in many ecosystems as the limiting nutrient, where it is broadly considered to reside as pentavalent P in phosphate minerals and organic esters. Exceptions to pentavalent P include phosphine--PH3--a trace atmospheric gas, and phosphite and hypophosphite, P anions that have been detected recently in lightning strikes, eutrophic lakes, geothermal springs, and termite hindguts. Reduced oxidation state P compounds include the phosphonates, characterized by C-P bonds, which bear up to 25% of total organic dissolved phosphorus. Reduced P compounds have been considered to be rare; however, the microbial ability to use reduced P compounds as sole P sources is ubiquitous. Here we show that between 10% and 20% of dissolved P bears a redox state of less than +5 in water samples from central Florida, on average, with some samples bearing almost as much reduced P as phosphate. If the quantity of reduced P observed in the water samples from Florida studied here is broadly characteristic of similar environments on the global scale, it accounts well for the concentration of atmospheric phosphine and provides a rationale for the ubiquity of phosphite utilization genes in nature. Phosphine is generated at a quantity consistent with thermodynamic equilibrium established by the disproportionation reaction of reduced P species. Comprising 10-20% of the total dissolved P inventory in Florida environments, reduced P compounds could hence be a critical part of the phosphorus biogeochemical cycle, and in turn may impact global carbon cycling and methanogenesis.

  1. Redox Flow Batteries, Hydrogen and Distributed Storage.

    Science.gov (United States)

    Dennison, C R; Vrubel, Heron; Amstutz, Véronique; Peljo, Pekka; Toghill, Kathryn E; Girault, Hubert H

    2015-01-01

    Social, economic, and political pressures are causing a shift in the global energy mix, with a preference toward renewable energy sources. In order to realize widespread implementation of these resources, large-scale storage of renewable energy is needed. Among the proposed energy storage technologies, redox flow batteries offer many unique advantages. The primary limitation of these systems, however, is their limited energy density which necessitates very large installations. In order to enhance the energy storage capacity of these systems, we have developed a unique dual-circuit architecture which enables two levels of energy storage; first in the conventional electrolyte, and then through the formation of hydrogen. Moreover, we have begun a pilot-scale demonstration project to investigate the scalability and technical readiness of this approach. This combination of conventional energy storage and hydrogen production is well aligned with the current trajectory of modern energy and mobility infrastructure. The combination of these two means of energy storage enables the possibility of an energy economy dominated by renewable resources.

  2. Wine consumption and intestinal redox homeostasis

    Science.gov (United States)

    Biasi, Fiorella; Deiana, Monica; Guina, Tina; Gamba, Paola; Leonarduzzi, Gabriella; Poli, Giuseppe

    2014-01-01

    Regular consumption of moderate doses of wine is an integral part of the Mediterranean diet, which has long been considered to provide remarkable health benefits. Wine׳s beneficial effect has been attributed principally to its non-alcoholic portion, which has antioxidant properties, and contains a wide variety of phenolics, generally called polyphenols. Wine phenolics may prevent or delay the progression of intestinal diseases characterized by oxidative stress and inflammation, especially because they reach higher concentrations in the gut than in other tissues. They act as both free radical scavengers and modulators of specific inflammation-related genes involved in cellular redox signaling. In addition, the importance of wine polyphenols has recently been stressed for their ability to act as prebiotics and antimicrobial agents. Wine components have been proposed as an alternative natural approach to prevent or treat inflammatory bowel diseases. The difficulty remains to distinguish whether these positive properties are due only to polyphenols in wine or also to the alcohol intake, since many studies have reported ethanol to possess various beneficial effects. Our knowledge of the use of wine components in managing human intestinal inflammatory diseases is still quite limited, and further clinical studies may afford more solid evidence of their beneficial effects. PMID:25009781

  3. Near coast sedimentary stratigraphy as a proxy for climatic instability

    Science.gov (United States)

    McLivenny, J.

    2009-04-01

    Several studies have indicated a link between climatic deterioration and dune stability (Wilson 2002, Issar 2003, Dawson et al 2004). The frequency and magnitude of storms have been cited as a key variable in the stability of large dune systems. For the stratigraphy of dune systems to act as a regional climatic proxy there must be a good regional relationship between known climatic events and regionally correlated stratigraphic changes. Dunnet Bay in Caithness, Northern Scotland was chosen as a study site to look at the relationship between dune stability and climatic change during the late Holocene in Northern Scotland. Dunnet Bay was chosen for its physical attributes which make it an excellent natural sediment trap. Tucked in between headlands which act as barriers to long-shore transport the predominant movement of sediment there is straight onshore, with only minor amounts being lost to the sea. The immediate back-dune stratigraphy, colloquially known as "links", provided evidence of peat formation and dune stability. Stratigraphy was mapped using traditional field techniques and ground penetrating radar. The cores consisted mostly of massive layers of sand interleaved with peat. Sand layers were dated with optically stimulated luminescence (OSL) and interpreted as reflecting high wind energy regimes transporting sand inland. Peat layers were C14 dated and taken as representing climatic stability. Stratigraphy was mapped using hand auguring, percussion coring, and open sections. Ground penetrating radar was also used to look at the continuity of key layers. OSL dating in two open sections showed dates obtained from the first section (1790 AD ±70, 53 BC ± 100, 300 BC ± 100, 400 BC ± 100) mapped to the top of the second section (1800 AD ± 100, 1500 BC ± 200, 2900 BC ± 300) which was consistent with stratigraphy increasing sediment thickness towards the centre of the bay. The results were consistent with acquired C14 dates from selected peat layers. Taken

  4. Accelerated redox reaction between chromate and phenolic pollutants during freezing

    Energy Technology Data Exchange (ETDEWEB)

    Ju, Jinjung; Kim, Jaesung [Department of Environmental Sciences and Biotechnology, Hallym University, Chuncheon, Gangwon-do 24252 (Korea, Republic of); Vetráková, Ľubica [Department of Chemistry and Research Centre for Toxic Compounds in the Environment (RECETOX), Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno (Czech Republic); Seo, Jiwon [School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919 (Korea, Republic of); Heger, Dominik [Department of Chemistry and Research Centre for Toxic Compounds in the Environment (RECETOX), Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno (Czech Republic); Lee, Changha [School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919 (Korea, Republic of); Yoon, Ho-Il [Korea Polar Research Institute (KOPRI), Incheon 21990 (Korea, Republic of); Kim, Kitae, E-mail: ktkim@kopri.re.kr [Korea Polar Research Institute (KOPRI), Incheon 21990 (Korea, Republic of); Kim, Jungwon, E-mail: jwk@hallym.ac.kr [Department of Environmental Sciences and Biotechnology, Hallym University, Chuncheon, Gangwon-do 24252 (Korea, Republic of)

    2017-05-05

    Highlights: • Redox conversion of 4-CP/Cr(VI) was significantly accelerated during freezing. • Accelerated redox conversion in ice is ascribed to the freeze concentration effect. • 4-CP, Cr(VI), and protons are concentrated in the liquid brine by freezing. • Redox conversions of various phenolic pollutants/Cr(VI) were significant in ice. • Freezing-accelerated redox conversion was observed in real polluted water. - Abstract: The redox reaction between 4-chlorophenol (4-CP) and chromate (Cr(VI)) (i.e., the simultaneous oxidation of 4-CP by Cr(VI) and reduction of Cr(VI) by 4-CP) in ice (i.e., at −20 °C) was compared with the corresponding reaction in water (i.e., at 25 °C). The redox conversion of 4-CP/Cr(VI), which was negligible in water, was significantly accelerated in ice. This accelerated redox conversion of 4-CP/Cr(VI) in ice is ascribed to the freeze concentration effect occurring during freezing, which excludes solutes (i.e., 4-CP and Cr(VI)) and protons from the ice crystals and subsequently concentrates them in the liquid brine. The concentrations of Cr(VI) and protons in the liquid brine were confirmed by measuring the optical image and the UV–vis absorption spectra of cresol red (CR) as a pH indicator of frozen solution. The redox conversion of 4-CP/Cr(VI) was observed in water when the concentrations of 4-CP/protons or Cr(VI)/protons increased by 100/1000-fold. These results corroborate the freeze concentration effect as the reason for the accelerated redox conversion of 4-CP/Cr(VI) in ice. The redox conversion of various phenolic pollutants/Cr(VI) and 4-CP/Cr(VI) in real wastewater was successfully achieved in ice, which verifies the environmental relevance and importance of freezing-accelerated redox conversion of phenolic pollutants/Cr(VI) in cold regions.

  5. Recognition memory for pictorial stimuli: biasing effects of stimulus emotionality.

    Science.gov (United States)

    Fernández-Rey, José; Redondo, Jaime

    2007-08-01

    The possibility that stimulus emotionality might influence recognition bias in a long-term memory task was studied with respect to both the valence and arousal dimensions of emotion. For this purpose, we used 108 International Affective Picture System pictures that were representative of all regions of this two-dimensional space. Signal detection theory analysis was applied using A'and B'' D as discrimination and bias measures, respectively. In general, the results showed that greater discrimination was accompanied by a response bias that was more conservative for pleasant and for unarousing pictures than for unpleasant and for arousing ones. These results provide new evidence in connection with the emotion-induced recognition bias in long-term memory performance.

  6. Using Resin-Based 3D Printing to Build Geometrically Accurate Proxies of Porous Sedimentary Rocks.

    Science.gov (United States)

    Ishutov, Sergey; Hasiuk, Franciszek J; Jobe, Dawn; Agar, Susan

    2017-09-28

    Three-dimensional (3D) printing is capable of transforming intricate digital models into tangible objects, allowing geoscientists to replicate the geometry of 3D pore networks of sedimentary rocks. We provide a refined method for building scalable pore-network models ("proxies") using stereolithography 3D printing that can be used in repeated flow experiments (e.g., core flooding, permeametry, porosimetry). Typically, this workflow involves two steps, model design and 3D printing. In this study, we explore how the addition of post-processing and validation can reduce uncertainty in the 3D-printed proxy accuracy (difference of proxy geometry from the digital model). Post-processing is a multi-step cleaning of porous proxies involving pressurized ethanol flushing and oven drying. Proxies are validated by: (1) helium porosimetry and (2) digital measurements of porosity from thin-section images of 3D-printed proxies. 3D printer resolution was determined by measuring the smallest open channel in 3D-printed "gap test" wafers. This resolution (400 µm) was insufficient to build porosity of Fontainebleau sandstone (∼13%) from computed tomography data at the sample's natural scale, so proxies were printed at 15-, 23-, and 30-fold magnifications to validate the workflow. Helium porosities of the 3D-printed proxies differed from digital calculations by up to 7% points. Results improved after pressurized flushing with ethanol (e.g., porosity difference reduced to ∼1% point), though uncertainties remain regarding the nature of sub-micron "artifact" pores imparted by the 3D printing process. This study shows the benefits of including post-processing and validation in any workflow to produce porous rock proxies. © 2017, National Ground Water Association.

  7. Preparation of redox polymer cathodes for thin film rechargeable batteries

    Energy Technology Data Exchange (ETDEWEB)

    Skotheim, T.A.; Lee, H.S.; Okamoto, Yoshiyuki.

    1994-11-08

    The present invention relates to the manufacture of thin film solid state electrochemical devices using composite cathodes comprising a redox polymer capable of undergoing oxidation and reduction, a polymer solid electrolyte and conducting carbon. The polymeric cathode material is formed as a composite of radiation crosslinked polymer electrolytes and radiation crosslinked redox polymers based on polysiloxane backbones with attached organosulfur side groups capable of forming sulfur-sulfur bonds during electrochemical oxidation.

  8. Alternative Evaluation for the REDOX (202-S) Plutonium Loadout Hood

    Energy Technology Data Exchange (ETDEWEB)

    N. R. Kerr

    1999-09-20

    Located in the 200 Areas is the inactive 202-S Reduction Oxidation (REDOX) Facility, which is managed by the Bechtel Hanford, Inc. Surveillance/Maintenance and Transition project. This facility is contaminated from nuclear material processes related to nuclear material separation from Hanford Site facility operations. This alternative evaluation report describes the alternatives and selection criteria based on the necessary protective requirements to maintain the REDOX Plutonium Loadout Hood in a safe and stable condition awaiting a final waste response action.

  9. Redox processes and water quality of selected principal aquifer systems

    Science.gov (United States)

    McMahon, P.B.; Chapelle, F.H.

    2008-01-01

    Reduction/oxidation (redox) conditions in 15 principal aquifer (PA) systems of the United States, and their impact on several water quality issues, were assessed from a large data base collected by the National Water-Quality Assessment Program of the USGS. The logic of these assessments was based on the observed ecological succession of electron acceptors such as dissolved oxygen, nitrate, and sulfate and threshold concentrations of these substrates needed to support active microbial metabolism. Similarly, the utilization of solid-phase electron acceptors such as Mn(IV) and Fe(III) is indicated by the production of dissolved manganese and iron. An internally consistent set of threshold concentration criteria was developed and applied to a large data set of 1692 water samples from the PAs to assess ambient redox conditions. The indicated redox conditions then were related to the occurrence of selected natural (arsenic) and anthropogenic (nitrate and volatile organic compounds) contaminants in ground water. For the natural and anthropogenic contaminants assessed in this study, considering redox conditions as defined by this framework of redox indicator species and threshold concentrations explained many water quality trends observed at a regional scale. An important finding of this study was that samples indicating mixed redox processes provide information on redox heterogeneity that is useful for assessing common water quality issues. Given the interpretive power of the redox framework and given that it is relatively inexpensive and easy to measure the chemical parameters included in the framework, those parameters should be included in routine water quality monitoring programs whenever possible.

  10. Complexation Key to a pH Locked Redox Reaction

    Science.gov (United States)

    Rizvi, Masood Ahmad; Dangat, Yuvraj; Shams, Tahir; Khan, Khaliquz Zaman

    2016-01-01

    An unfavorable pH can block a feasible electron transfer for a pH dependent redox reaction. In this experiment, a series of potentiometric titrations demonstrate the sequential loss in feasibility of iron(II) dichromate redox reaction over a pH range of 0-4. The pH at which this reaction failed to occur was termed as a pH locked reaction. The…

  11. Redox-active polypyrrole: toward polymer-based batteries

    Energy Technology Data Exchange (ETDEWEB)

    Song, H.K. [Division of Engineering, Brown University, Providence, RI 02912 (United States); Palmore, G.T.R. [Division of Engineering, Brown University, Providence, RI 02912 (United States); Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, RI 02912 (United States)

    2006-07-04

    An energy-storage device consisting of polypyrrole (pPy) doped with indigo carmine (IC) and 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) has been fabricated. These redox-active conducting polymers form the basis of a battery that depends on the faradaic reactions of the redox-active dopants, and performs better than conventional batteries and ultracapacitors at high power density. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  12. Development of a zinc-cerium redox flow battery

    OpenAIRE

    Leung, P.K.

    2011-01-01

    Redox flow batteries (RFBs) can be used to store energy on the large and medium scale(kW – MW), particularly in applications such as load levelling of electrical powersupplies, power quality control application and facilitating renewable energy deployment.In this thesis, the development of a divided and undivided zinc-cerium redox flow batteryfrom its fundamental chemistry in aqueous methanesulfonic acid has been described. Thiscomprehensive investigation has focused on the selection of elect...

  13. The perception of regularity in an isochronous stimulus in zebra finches (Taeniopygia guttata) and humans.

    Science.gov (United States)

    van der Aa, Jeroen; Honing, Henkjan; ten Cate, Carel

    2015-06-01

    Perceiving temporal regularity in an auditory stimulus is considered one of the basic features of musicality. Here we examine whether zebra finches can detect regularity in an isochronous stimulus. Using a go/no go paradigm we show that zebra finches are able to distinguish between an isochronous and an irregular stimulus. However, when the tempo of the isochronous stimulus is changed, it is no longer treated as similar to the training stimulus. Training with three isochronous and three irregular stimuli did not result in improvement of the generalization. In contrast, humans, exposed to the same stimuli, readily generalized across tempo changes. Our results suggest that zebra finches distinguish the different stimuli by learning specific local temporal features of each individual stimulus rather than attending to the global structure of the stimuli, i.e., to the temporal regularity. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Influence of source vegetation and redox conditions on lignin-based decomposition proxies in graminoid-dominated ombrotrophic peat (Penido Vello, NW Spain)

    NARCIS (Netherlands)

    Schellekens, J.; Buurman, P.; Kuyper, T.W.; Abbott, G.D.; Pontevedra-Pombal, X.; Martinez-Cortizas, A.

    2015-01-01

    Most knowledge about the degradation of lignocellulose in natural environments is based on woody tissue and aerobic systems; however, in peatlands the contribution of graminoids to organic matter (OM) is often significant and anaerobic conditions prevail. In order to reconstruct past environmental

  15. Reply to comment by Marks et al. (2016) on "Apatite: A new redox proxy for silicic magmas?" [Geochimica et Cosmochimica Acta 132 (2014) 101-119

    Science.gov (United States)

    Miles, Andrew; Graham, Colin; Hawkesworth, Chris; Gillespie, Martin; Hinton, Richard; Bromiley, Geoffrey; Emmac

    2016-06-01

    Marks et al. (2016) investigate the applicability of the Mn-in-apatite oxybarometer proposed by Miles et al. (2014) across a range of magma compositions using published data on well-characterised samples. The authors show that for magma compositions outside of the calc-alkaline and intermediate to silicic range used in the preliminary calibration, fO2 values calculated from Mn-in-apatite vary significantly from independently constrained estimates. These data are used to reiterate our warnings that other controls that are additional to oxygen fugacity are likely to affect Mn partitioning into apatite in some rock types, and particularly so in magmas that lie outside of the range of compositions and conditions used in the calibration. Marks et al. (2016) highlight that temperature may have an especially important effect on Mn partitioning in apatite in some rock types.

  16. An ethical analysis of proxy and waiver of consent in critical care research

    DEFF Research Database (Denmark)

    Berg, Ronan M G; Møller, Kirsten; Rossel, Peter J. Hancke

    2013-01-01

    a substituted judgement by a close relative or friend, based on knowledge of patient's values, preferences, and view of life. For the consent to be genuine, the proxy must be informed of and understand three fundamental aspects of research practice: (1) that participation is voluntary and the consent can......It is a central principle in medical ethics that vulnerable patients are entitled to a degree of protection that reflects their vulnerability. In critical care research, this protection is often established by means of so-called proxy consent. Proxy consent for research participation constitutes...

  17. Redox Disproportionation of Glucose as a Major Biosynthetic Energy Source

    Science.gov (United States)

    Weber, Arthur L.

    1996-01-01

    Previous studies have concluded that very little if any energy is required for the microbial biosynthesis of amino acids and lipids from glucose -- processes that yield almost as much ATP (adenosine triphosphate) as they consume. However, these studies did not establish the strength nor the nature of the energy source driving these biological transformations. To identify and estimate the strength of the energy source behind these processes, we calculated the free energy change due to the redox disproportionation of substrate carbon of (a) 26 redox-balanced fermentation reactions, and (b) the biosynthesis of amino acids, lipids, and nucleotides of E. coli from glucose. A plot of the negative free energy of these reactions per mmole of carbon as a function of the number of disproportionative electron transfers per mmol of carbon showed that the energy yields of these fermentations and biosyntheses were directly proportional to the degree of redox disproportionation of carbon. Since this linear relationship showed that redox disproportionation was the dominant energy source of these reactions, we were able to establish that amino acid and lipid biosynthesis obtained most of their energy from redox disproportionation (greater than 94%). In contrast nucleotide biosynthesis was not driven by redox disproportionation of carbon, and consequently depended completely on ATP for energy. This crucial and previously unrecognized role of sugars as an energy source of biosynthesis suggests that sugars were involved at the earliest stage in the origin of anabolic metabolism.

  18. Polyoxovanadate-Alkoxide Clusters as a Redox Reservoir for Iron.

    Science.gov (United States)

    Li, Feng; Carpenter, Stephanie H; Higgins, Robert F; Hitt, Mark G; Brennessel, William W; Ferrier, Maryline G; Cary, Samantha K; Lezama-Pacheco, Juan S; Wright, Joshua T; Stein, Benjamin W; Shores, Matthew P; Neidig, Michael L; Kozimor, Stosh A; Matson, Ellen M

    2017-06-19

    Inspired by the multielectron redox chemistry achieved using conventional organic-based redox-active ligands, we have characterized a series of iron-functionalized polyoxovanadate-alkoxide clusters in which the metal oxide scaffold functions as a three-dimensional, electron-deficient metalloligand. Four heterometallic clusters were prepared through sequential reduction, demonstrating that the metal oxide scaffold is capable of storing up to four electrons. These reduced products were characterized by cyclic voltammetry, IR, electronic absorption, and (1)H NMR spectroscopies. Moreover, Mössbauer and X-ray absorption spectroscopies suggest that the redox events involve primarily the vanadium ions, while the iron atoms remained in the 3+ oxidation state throughout the redox series. In this sense, the vanadium portion of the cluster mimics a conventional organic-based redox-active ligand bound to an iron(III) ion. Magnetic coupling within the hexanuclear cluster was characterized using SQUID magnetometry. Overall, the results suggest extensive electronic delocalization between the metal centers of the cluster core. These results demonstrate the ability of electronically flexible, reducible metal oxide supports to function as redox-active reservoirs for transition-metal centers.

  19. Redox Impact on Starch Biosynthetic Enzymes in Arabidopsis thaliana

    DEFF Research Database (Denmark)

    Skryhan, Katsiaryna

    Summary The thesis provides new insight into the influence of the plant cell redox state on the transient starch metabolism in Arabidopsis thaliana with a focus on starch biosynthetic enzymes. Two main hypotheses forms the basis of this thesis: 1) photosynthesis and starch metabolism are coordina......Summary The thesis provides new insight into the influence of the plant cell redox state on the transient starch metabolism in Arabidopsis thaliana with a focus on starch biosynthetic enzymes. Two main hypotheses forms the basis of this thesis: 1) photosynthesis and starch metabolism...... are coordinated by the redox state of the cell via post-translational modification of the starch metabolic enzymes containing redox active cysteine residues and these cysteine residues became cross-linked upon oxidation providing a conformational change leading to activity loss; 2) cysteine residues...... of chloroplast enzymes can play a role not only in enzyme activity and redox sensitivity but also in protein folding and stability upon oxidation. Several redox sensitive enzymes identified in this study can serve as potential targets to control the carbon flux to and from starch during the day and night...

  20. Molecular engineering of organic electroactive materials for redox flow batteries.

    Science.gov (United States)

    Ding, Yu; Zhang, Changkun; Zhang, Leyuan; Zhou, Yangen; Yu, Guihua

    2017-10-18

    With high scalability and independent control over energy and power, redox flow batteries (RFBs) stand out as an important large-scale energy storage system. However, the widespread application of conventional RFBs is limited by the uncompetitive performance, as well as the high cost and environmental concerns associated with the use of metal-based redox species. In consideration of advantageous features such as potentially low cost, vast molecular diversity, and highly tailorable properties, organic and organometallic molecules emerge as promising alternative electroactive species for building sustainable RFBs. This review presents a systematic molecular engineering scheme for designing these novel redox species. We provide detailed synthetic strategies for modifying the organic and organometallic redox species in terms of solubility, redox potential, and molecular size. Recent advances are then introduced covering the reaction mechanisms, specific functionalization methods, and electrochemical performances of redox species classified by their molecular structures. Finally, we conclude with an analysis of the current challenges and perspectives on future directions in this emerging research field.

  1. Neural correlates of the formation and retention of cocaine-induced stimulus-reward associations

    OpenAIRE

    Nelissen, Koen; Jarraya, Bechir; Arsenault, John; Rosen, Bruce; Wald, Lawrence,; Mandeville, Joseph; Marota, John; Vanduffel, Wim

    2012-01-01

    Background: Cocaine can elicit drug-seeking behavior for drug-predicting stimuli, even after a single stimulus-cocaine pairing. While orbitofrontal cortex is thought to be important during encoding and maintenance of stimulus-reward value, we still lack a comprehensive model of the neural circuitry underlying this cognitive process. Methods: We studied the conditioned effects of cocaine using monkey fMRI and classical conditioning by pairing a visual shape (conditioning stimulus, CS+) wit...

  2. Lifespan development of stimulus-response conflict cost: similarities and differences between maturation and senescence

    OpenAIRE

    Li, S.; Hämmerer, D.; Müller, V.; Hommel, B.; Lindenberger, U.

    2008-01-01

    Age gradient of the mechanism of stimulus-response conflict cost was investigated in a population-based representative sample of 291 individuals, covering the age range from 6 to 89 years. Stimulus-response conflict cost, indicated by the amount of additional processing time required when there is a conflict between stimulus and response options, follows a U-shaped function across the lifespan. Lifespan age gradient of conflict cost parallels closely those of processing fluctuation and fluid ...

  3. A carbon-free lithium-ion solid dispersion redox couple with low viscosity for redox flow batteries

    Science.gov (United States)

    Qi, Zhaoxiang; Koenig, Gary M.

    2016-08-01

    A new type of non-aqueous redox couple without carbon additives for flow batteries is proposed and the target anolyte chemistry is demonstrated. The so-called ;Solid Dispersion Redox Couple; incorporates solid electroactive materials dispersed in organic lithium-ion battery electrolyte as its flowing suspension. In this work, a unique and systematic characterization approach has been used to study the flow battery redox couple in half cell demonstrations relative to a lithium electrode. An electrolyte laden with Li4Ti5O12 (LTO) has been characterized in multiple specially designed lithium half cell configurations. The flow battery redox couple described in this report has relatively low viscosity, especially in comparison to other flow batteries with solid active materials. The lack of carbon additive allows characterization of the electrochemical properties of the electroactive material in flow without the complication of conductive additives and unambiguous observation of the electrorheological coupling in these dispersed particle systems.

  4. Redox potential: An indicator of site productivity in forest management

    Science.gov (United States)

    Sajedi, Toktam; Prescott, Cindy; Lavkulich, Les

    2010-05-01

    Redox potential (Eh) is an integrated soil measurement that reflects several environmental conditions in the soil associated with aeration, moisture and carbon (organic matter) dynamics. Its measurement can be related to water table fluctuations, precipitation and landscape gradients, organic matter decomposition rates, nutrient dynamics, biological diversity and plant species distribution. Redox is an excellent indicator of soil biological processes, as it is largely a reflection of microbial activities which to a large extent govern carbon dynamics and nutrient cycling. Redox thus serves as an ecological indicator of site productivity at the ecosystem scale and may be used for management purposes as its magnitude can be altered by activities such as harvesting and drainage. A threshold value of 300 mv has been documented as the critical value below which anaerobic conditions in the soil develop. However, redox measurements and its impacts on ecosystem processes such as nutrient cycling and productivity, especially in forest ecosystems, have not received the attention that this "master" variable deserves, On northern Vancouver Island, Canada, regenerating stands of western redcedar-western hemlock (CH) sites exhibit symptoms of nutrient deficiencies and slow growth, but this phenomenon does not occur on adjacent western hemlock- amabalis fir (HA) sites. We tested the hypothesis that differences in nutrient supply and distribution of plant species was caused by differences in moisture regime and redox potential. Redox potential, pH, soil aeration depth (steel rods), organic matter thickness, bulk density, soil carbon store, plant species distribution and richness were measured at five old-growth and five 10-year-old cutover blocks. Results of investigations confirmed that CH forests were wetter, had redox values lower than the critical 300mv and a shallower aerated zone, compared with adjacent regenerating HA sites. Fifty percent of the CH plots had redox values

  5. Order of stimulus presentation modulates interference in Stroop matching tasks: a reaction time study

    OpenAIRE

    Caldas, Ariane Leão; David, Isabel de Paula Antunes; Portes, Paula Martins; Portugal, Anna Carolina de Almeida; Machado-Pinheiro, Walter

    2015-01-01

    In the classic Stroop effect, the time spent to name the color of an incongruent stimulus (GREEN in blue) is longer than the time necessary to name the color of a congruent stimulus (BLUE in blue). In the “Stroop matching task”, volunteers are instructed to compare attributes of two stimuli, in which one of them is necessarily a Stroop stimulus. Our aim was to investigate whether the order of stimulus presentation can explain some contradictory results and reveal the imposition of high-order ...

  6. The Impacts of Facial Tones and Stimulus Durations on Perceived Oldness and Attractiveness

    Directory of Open Access Journals (Sweden)

    Ji Yeon Lee

    2011-05-01

    Full Text Available Two experiments were conducted to investigate the impacts of facial tone and stimulus duration on perceived oldness and judgement of attraction. The stimulus were facial images of Asians. Facial tone (bright, middle, dark and stimulus duration (50ms, 200ms, 800ms were manipulated. In Experiment 1 perceived oldness was measured, and in Experiment 2 attractiveness was evaluated. The results showed that face was perceived older and less attractive with increase facial tone facial regardless of stimulus duration. This suggest that perceived oldness and judgement of attraction are closely related and affected primarily by facial tone.

  7. Redox-Flow Batteries: From Metals to Organic Redox-Active Materials.

    Science.gov (United States)

    Winsberg, Jan; Hagemann, Tino; Janoschka, Tobias; Hager, Martin D; Schubert, Ulrich S

    2017-01-16

    Research on redox-flow batteries (RFBs) is currently experiencing a significant upturn, stimulated by the growing need to store increasing quantities of sustainably generated electrical energy. RFBs are promising candidates for the creation of smart grids, particularly when combined with photovoltaics and wind farms. To achieve the goal of "green", safe, and cost-efficient energy storage, research has shifted from metal-based materials to organic active materials in recent years. This Review presents an overview of various flow-battery systems. Relevant studies concerning their history are discussed as well as their development over the last few years from the classical inorganic, to organic/inorganic, to RFBs with organic redox-active cathode and anode materials. Available technologies are analyzed in terms of their technical, economic, and environmental aspects; the advantages and limitations of these systems are also discussed. Further technological challenges and prospective research possibilities are highlighted. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  8. A Membrane-Free Redox Flow Battery with Two Immiscible Redox Electrolytes.

    Science.gov (United States)

    Navalpotro, Paula; Palma, Jesus; Anderson, Marc; Marcilla, Rebeca

    2017-10-02

    Flexible and scalable energy storage solutions are necessary for mitigating fluctuations of renewable energy sources. The main advantage of redox flow batteries is their ability to decouple power and energy. However, they present some limitations including poor performance, short-lifetimes, and expensive ion-selective membranes as well as high price, toxicity, and scarcity of vanadium compounds. We report a membrane-free battery that relies on the immiscibility of redox electrolytes and where vanadium is replaced by organic molecules. We show that the biphasic system formed by one acidic solution and one ionic liquid, both containing quinoyl species, behaves as a reversible battery without any membrane. This proof-of-concept of a membrane-free battery has an open circuit voltage of 1.4 V with a high theoretical energy density of 22.5 Wh L -1 , and is able to deliver 90 % of its theoretical capacity while showing excellent long-term performance (coulombic efficiency of 100 % and energy efficiency of 70 %). © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  9. Enhanced Collaboration for Space Situational Awareness via Proxy Agents

    Science.gov (United States)

    Picciano, P.; Schurr, N.

    2012-09-01

    The call for dynamic partnerships demanded in the US. Space Policy confronts two formidable challenges. The first is evident in the lack of the adoption of technical innovations that could substantially enhance collaboration. The second category, and perhaps a greater impediment, involves organizational and social constraints that minimize information sharing. Compounding the technical challenges, the organizational barriers to collaboration present a different problem set. There is a culture in the space domain that predisposes most stakeholders to guard their information. Most owner/operators are reluctant to share asset data, whether experiencing an anomaly or just providing status updates. This is unfortunate, because the owner/operators generally have the most accurate and timely data pertaining to their satellite. Comprehensive Space Situational Awareness (SSA) requires the marshaling of disparate mission critical elements. The mission threads reliant on SSA are complex and often require analysis from a diverse team of experts with sophisticated systems and tools that may be dispersed across multiple entities including military, commercial, and public interests. Two significant trends are likely to further perpetuate this state of affairs: 1) the space environment continues to be more congested, contested, and competitive, and 2) further pressures to increase SSA Sharing with a greater number of stakeholders throughout the world. The challenge of delivering the right information to the right people, while protecting national security and privacy interests, is in need of an innovative solution. Our approach, entitled Space Collaboration via an Agent Network (SCAN), enables proxy software agents to represent stakeholders (as individuals and organizations) to enhance collaboration among various agency producers and consumers of space information The SCAN agent network will facilitate collaboration by identifying opportunities to collaborate, as well as optimize

  10. Breast Cancer: A Molecular and Redox Snapshot.

    Science.gov (United States)

    Raman, Deepika; Foo, Chuan Han Jonathan; Clement, Marie-Veronique; Pervaiz, Shazib

    2016-08-20

    Breast cancer is a unique disease characterized by heterogeneous cell populations causing roadblocks in therapeutic medicine, owing to its complex etiology and primeval understanding of the biology behind its genesis, progression, and sustenance. Globocan statistics indicate over 1.7 million new breast cancer diagnoses in 2012, accounting for 25% of all cancer morbidities. Despite these dismal statistics, the introduction of molecular gene signature platforms, progressive therapeutic approaches in diagnosis, and management of breast cancer has led to more effective treatment strategies and control measures concurrent with an equally reassuring decline in the mortality rate. However, an enormous body of research in this area is requisite as high mortality associated with metastatic and/or drug refractory tumors continues to present a therapeutic challenge. Despite advances in systemic chemotherapy, the median survival of patients harboring metastatic breast cancers continues to be below 2 years. Hence, a massive effort to scrutinize and evaluate chemotherapeutics on the basis of the molecular classification of these cancers is undertaken with the objective to devise more attractive and feasible approaches to treat breast cancers and improve patients' quality of life. This review aims to summarize the current understanding of the biology of breast cancer as well as challenges faced in combating breast cancer, with special emphasis on the current battery of treatment strategies. We will also try and gain perspective from recent encounters on novel findings responsible for the progression and metastatic transformation of breast cancer cells in an endeavor to develop more targeted treatment options. Antioxid. Redox Signal. 25, 337-370.

  11. Hygroscopic growth and cloud droplet activation of xanthan gum as a proxy for marine hydrogels

    National Research Council Canada - National Science Library

    Dawson, K. W; Petters, M. D; Meskhidze, N; Petters, S. Suda; Kreidenweis, S. M

    2016-01-01

    .... Here we use xanthan gum (XG)—a bacterial biopolymer—as a proxy for marine hydrogels. Measurements were performed for pure XG particles and mixtures of XG with sodium chloride, calcium nitrate, and calcium carbonate...

  12. Middleware Proxy: A Request-Driven Messaging Broker For High Volume Data Distribution

    CERN Document Server

    Sliwinski, W; Dworak, A

    2014-01-01

    Nowadays, all major infrastructures and data centres (commercial and scientific) make an extensive use of the publish-subscribe messaging paradigm, which helps to decouple the message sender (publisher) from the message receiver (consumer). This paradigm is also heavily used in the CERN Accelerator Control system, in Proxy broker - critical part of the Controls Middleware (CMW) project. Proxy provides the aforementioned publish-subscribe facility and also supports execution of synchronous read and write operations. Moreover, it enables service scalability and dramatically reduces the network resources and overhead (CPU and memory) on publisher machine, required to serve all subscriptions. Proxy was developed in modern C++, using state of the art programming techniques (e.g. Boost) and following recommended software patterns for achieving low-latency and high concurrency. The outstanding performance of the Proxy infrastructure was confirmed during the last 3 years by delivering the high volume of LHC equipment...

  13. Youth proxy efficacy for fruit and vegetable availability varies by gender and socio-economic status.

    Science.gov (United States)

    Geller, Karly S; Dzewaltowski, David A

    2010-06-01

    The current study examined proxy efficacy, which was defined as youth's confidence to influence their parents to provide fruits and vegetables. The overall objective was to examine change in middle-school youth's proxy efficacy over time, and to determine if changes were moderated by gender and socio-economic status. Longitudinal cohort nested within schools. Eight middle schools located in urban, suburban and rural areas of a mid-western US state. Seven hundred and twelve youth followed across their 6th, 7th and 8th grade years. The sample was 51.8 % female, 30.5 % low socio-economic status and 89.5 % Caucasian, non-Hispanic. Males and lower socio-economic status youth were significantly lower in proxy efficacy at each assessment year compared with females and high socio-economic youth, respectively. Proxy efficacy to influence parents to provide fruits and vegetables may be an important construct to target in future interventions.

  14. Multiple water isotope proxy reconstruction of extremely low last glacial temperatures in Eastern Beringia (Western Arctic)

    NARCIS (Netherlands)

    Porter, Trevor J.; Froese, Duane G.; Feakins, Sarah J.; Bindeman, Ilya N.; Mahony, Matthew E.; Pautler, Brent G.; Reichart, Gert-Jan; Sanborn, Paul T.; Simpson, Myrna J.; Weijers, Johan W H

    2016-01-01

    Precipitation isotopes are commonly used for paleothermometry in high latitude regions. Here we present multiple water isotope proxies from the same sedimentary context - perennially frozen loess deposits in the Klondike Goldfields in central Yukon, Canada, representing parts of Marine Isotope

  15. A Quantum Proxy Weak Blind Signature Scheme Based on Controlled Quantum Teleportation

    Science.gov (United States)

    Cao, Hai-Jing; Yu, Yao-Feng; Song, Qin; Gao, Lan-Xiang

    2015-04-01

    Proxy blind signature is applied to the electronic paying system, electronic voting system, mobile agent system, security of internet, etc. A quantum proxy weak blind signature scheme is proposed in this paper. It is based on controlled quantum teleportation. Five-qubit entangled state functions as quantum channel. The scheme uses the physical characteristics of quantum mechanics to implement message blinding, so it could guarantee not only the unconditional security of the scheme but also the anonymity of the messages owner.

  16. Human rights of children with intellectual disabilities: comparing self-ratings and proxy ratings.

    Science.gov (United States)

    Huus, K; Granlund, M; Bornman, J; Lygnegård, F

    2015-11-01

    A child rights-based approach to research articulates well with Article 12 of the United Nations Convention on the Rights of the Child (CRC) and highlights the importance and value of including children's own views about aspects that concern them. The aim of this study is to compare children with intellectual disability's own ratings (as self-raters) to those of their primary caregivers (as proxy raters) regarding human rights of children. The study also aims to establish whether there is an inter-rater agreement between the self-raters and proxy raters concerning Maslow's hierarchy of needs. This study is nested in a larger study examining the human rights of children with intellectual disability in South Africa. In total, 162 children with intellectual disability from 11 schools across three provinces and their primary caregivers participated by answering parts of a Children's Rights Questionnaire (CRQ) developed by the researchers based on the United Nation's CRC. We compared the answers for six questions in the questionnaire that were addressed to self-raters (children) and proxy raters (primary caregivers) in the same way. Questions regarding basic needs, such as access to clean water or whether the child had food to eat at home, were answered similarly by self-raters and proxy raters. Larger differences were found when self-raters and proxy raters were asked about whether the child had things or friends to play with at home. Socio-economic variables seemed to affect whether self-raters and proxy raters answered similarly. The results underscore the importance of promoting children's rights to express themselves by considering the opinions of both the children as self-raters and their primary caregivers as proxy raters - not only the latter. The results indicate that it is especially important to include children's own voices when more complex needs are surveyed. Agreement between self- and proxy ratings could be affected by socio-economic circumstances.

  17. Design and implementation of Ad-Hoc collaborative proxying scheme for reducing network energy waste

    OpenAIRE

    Rafiullah Khan; Sarmad Ullah Khan

    2017-01-01

    Network devices are equipped with low power states but they are rarely activated due to their inability of maintaining network connectivity. Recently, Network Connectivity Proxy (NCP) concept has been proposed in literature as an effective mechanism to exploit full potential of low power features on network devices by impersonating their virtual presence. However, the NCP concept faces several open issues and challenges especially related to proxying of TCP connections and majority of daily u...

  18. Similarity, agreement, and assumed similarity in proxy end-of-life decision making.

    Science.gov (United States)

    McDade-Montez, Elizabeth; Watson, David; Beer, Andrew

    2013-12-01

    Medical decisions near the end of life are often made by proxies who can be inaccurate in their judgments of patient preferences. Given that accuracy in surrogate decision making is an important goal in end-of-life decision making, and in light of that previously seen levels of accuracy reflect substantial disagreement, error, or both, this study examined both relationship and individual factors that potentially affect surrogate accuracy. Specifically, this study examined similarity, agreement, and assumed similarity-a process whereby raters use their own traits and preferences to rate another person-in spousal ratings of end-of-life treatment. This study expands on previous research by examining the potential influence of relationship factors and assumed similarity on end-of-life decision making among a sample of newlyweds. Newly married couples (n = 197) completed self and spouse measures of hypothetical end-of-life preferences and scales assessing marital satisfaction, personality, and attitudes. Results indicate a moderate level of similarity on husband and wife self-rated end-of-life treatment preferences (rs = .18-.29) and a moderate level of agreement between self and proxy ratings (rs = .17-.41). The largest correlations were seen between self ratings and proxy ratings (e.g., husband self ratings and husband proxy ratings of wife preferences, rs = .46-.69), reflecting strong assumed similarity in proxy ratings. For wives, similarity with husbands on a few attitudinal variables (i.e., spirituality, moral strictness, and conservatism) influenced proxy accuracy. Recognizing the potential impact of personal preferences on proxy ratings, as well as the potential influence of relationship factors, may help improve proxy accuracy and end-of-life care for patients and families.

  19. Contribution in Adaptating Web Interfaces to any Device on the Fly: The HCI Proxy

    Science.gov (United States)

    Lardon, Jérémy; Fayolle, Jacques; Gravier, Christophe; Ates, Mikaël

    2008-11-01

    Lot of work has been done on the adaptation of UIs. In the particular field of Web UI adaptation, many research projects aim at displaying web content designed for PCs on poorer supports. In this paper, we present previous work in the domain and then our proxy architecture, HCI proxy, to test solutions for the problem of adapting Web UIs for mobile phones, PDA and smartphones but also for TVs through browser-embedding STBs, and this on the fly.

  20. A Quantum Proxy Blind Signature Scheme Based on Genuine Five-Qubit Entangled State

    Science.gov (United States)

    Zeng, Chuan; Zhang, Jian-Zhong; Xie, Shu-Cui

    2017-06-01

    In this paper, a quantum proxy blind signature scheme based on controlled quantum teleportation is proposed. This scheme uses a genuine five-qubit entangled state as quantum channel and adopts the classical Vernam algorithm to blind message. We use the physical characteristics of quantum mechanics to implement delegation, signature and verification. Security analysis shows that our scheme is valid and satisfy the properties of a proxy blind signature, such as blindness, verifiability, unforgeability, undeniability.